Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1995-1999
  • 1990-1994  (737)
  • 1990  (737)
  • Chemical Engineering  (674)
  • Magnetic resonance imaging
  • Nuclear reactions
  • Theoretical, Physical and Computational Chemistry
Source
Material
Years
  • 1995-1999
  • 1990-1994  (737)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Association of anterior ectopic anus and partial absence of levator musculature in a woman with impaired defecation (1990)
    Springer
    Diseases of the colon & rectum 33 (1990), S. 974-976 
    Details
    ISSN: 1530-0358
    Keywords: Constipation ; Defecography ; Magnetic resonance imaging ; Anterior ectopic anus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 25-year-old nulliparous woman with adult onset constipation and slight anterior displacement of the anus underwent pelvic magnetic resonance imaging and was diagnosed with congenital hemiabsence of the levator ani sling. Impaired defecation was confirmed by anorectal function studies and defecography demonstrated an anterior rectocele, perineal descent at the upper limit of normal, and partial obstruction of defecation, which appeared related to the levator sling abnormality. To our knowledge, this combination of findings has not been previously described as a cause of adult onset constipation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02139109
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Volume determinations of the encephalic ventricles with CT and MRI (1990)
    Springer
    Surgical and radiologic anatomy 12 (1990), S. 59-64 
    Details
    ISSN: 1279-8517
    Keywords: Cerebral ventricular volume ; Cerebrospinal fluid volume ; Volume of encephalic ventricles ; Computerized tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Le volume des ventricules cérébraux a été mesuré à partir d'explorations en résonance magnétique. Il existe de nombreuses conditions pathologiques qui peuvent provoquer un élargissement ventriculaire, telles que la maladie d'Alzheimer et l'hydrocéphalie. La mesure précise de la taille des ventricules peut être d'importance pour le diagnostic de ces affections. Elle fournit également d'excellents critères de surveillance des patients porteurs de telles maladies. Notre objectif a été poursuivi au cours d'études séparées en 3 parties. Ce travail rapporte les résultats obtenus durant la première phase de cette étude. Celle-ci démontre qu'il est possible de mesurer les espaces liquidiens en IRM sur 3 fantômes ventriculaires (cavités petites, moyennes et larges). Les résultats ont été comparés avec ceux obtenus en examen tomodensitométrique des mêmes préparations. Des calculs volumétriques ont été obtenus à l'aide d'un analyseur numérique Calcomp 9 000 programmé pour corriger les facteurs d'agrandissement et les épaisseurs de coupe. L'étude des résultats des mesures de volume des cavités ventriculaires obtenus sur ces fantômes démontre que ceux-ci sont plus précis en coupes IRM qu'en coupes tomodensitométriques. La différence moyenne entre ces volumes obtenus en imagerie et les volumes réels calculés par mesure d'espaces liquidiens était de 15,8 % pour les coupes scanographiques et 8,3 % pour l'IRM.
    Notes: Summary The volume of the encephalic ventricles was determined from magnetic resonance imaging (MRI) scans. Since there are many conditions in which the encephalic ventricles become enlarged such as Alzheimer's disease and hydrocephalus, accurate measurement of the ventricles provides a valuable and safe means of aiding the diagnosis of such conditions and also provides important follow-up information in affected patients. The objective was pursued in a three phase study. This paper presents the data obtained from the first phase. This first phase demonstrated the possibility of measuring fluid filled spaces by MRI in three phantom preparations (small, medium, and large “ventricles”). The results were compared with those obtained from computerized tomography (CT) scans of the same preparations. These volumetric calculations were done with the aid of a Calcomp 9,000 digital analyzer programmed to compensate for the scale factor and slice thickness of the images. The phantom study showed that the results obtained from the MRI scans were better than those obtained from the CT scans in measuring the volume of water-filled cavities (ventricles) in gelatin phantoms. The average percent difference between volumes obtained by an imaging procedure compared to the actual volume as determined by water displacement was 15.8% for CT scanning and a more impressive 8.3% for MRI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02094127
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging of musculoaponeurotic fibromatosis (1990)
    Springer
    Skeletal radiology 19 (1990), S. 509-514 
    Details
    ISSN: 1432-2161
    Keywords: Musculoaponeurotic fibromatosis ; Magnetic resonance imaging ; Gadolinium-DTPA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Musculoaponeurotic fibromatosis can be mistaken for soft-tissue sarcoma both clinically and on X-ray computed tomography. Magnetic resonance imaging (MRI) in three patients with this condition enabled the correct diagnosis to be made prospectively in two. The appearance on MRI of a heterogeneous mass with well-defined, predominantly peripheral areas of very low signal intensity due to dense fibrous tissue and areas of medium to high signal intensity corresponding to a more cellular stroma should raise the the suspicion of musculoaponeurotic fibromatosis. Cellular areas within the tumour showed moderate enhancement after gadolinium diethylene triamine pentaacetic acid administration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202700
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    3D visualization of tomographic volume data using the generalized voxel model (1990)
    Springer
    The visual computer 6 (1990), S. 28-36 
    Details
    ISSN: 1432-2315
    Keywords: Computer tomography ; Magnetic resonance imaging ; Ray-casting algorithm ; Voxel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Multi-slice images obtained from computer tomography and magnetic resonance imaging represent a 3D image volume. For its visualization we use a raycasting algorithm working on a gray-scale voxel data model. This model is extended by additional attributes such as membership to an organ or a second imaging modality (“generalized voxel model”). It is shown that the combination of different surface-rendering algorithms together with cutting and transparent display allow a realistic visualization of the human anatomy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01902627
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Rebound of ICP after brain compression (1990)
    Springer
    Acta neurochirurgica 104 (1990), S. 126-135 
    Details
    ISSN: 0942-0940
    Keywords: Magnetic resonance imaging ; intracranial mass lesion ; intracranial pressure rebound ; brain oedema
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The rebound of intracranial pressure (ICP) occurring after decompression of an intracranial mass lesion was studied in an epidural balloon compression model. Intracranial morphology and brain tissue water content were assessed with magnetic resonance imaging (MRI). Fast and slow components of the transverse relaxation time (T2) were used as indicators of brain oedema development. During balloon compression a progressive prolongation of both the fast and the slow T2 components took place. Following deflation of the balloon both components increased rapidly, particularly the slow-T2. The MR scans displayed progressive occlusion of the aqueduct, and obliteration of the ambient and pontine cisterns. The changes in morphology and in water content after decompression had largely the same time course as the development of the rebound of ICP. In contrast, no changes in morphology and tissue water content occurred after hydrostatic brain compression achieved by subarachnoid fluid infusion. The findings suggest that the intracranial pressure rebound is caused by cerebral oedema accumulated during and particularly in the recirculation phase after an ischaemic injury of adequate intensity and adequate duration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01842830
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Evaluation of encephalic ventricular volume from the magnetic resonance imaging scans of thirty-eight human subjects (1990)
    Springer
    Surgical and radiologic anatomy 12 (1990), S. 287-290 
    Details
    ISSN: 1279-8517
    Keywords: Cerebral ventricular volume ; Cerebrospinal fluid volume ; Volume of encephalic ventricles ; Computerized tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé La détermination exacte du volume des ventricules cérébraux est importante en clinique comme par exemple dans la démence présénile d'Alzheimer, la schizophrénie et l'hypertension intracrânienne bénigne. Des études antérieures ont étudié la fiabilité de la résonance magnétique nucléaire en pratique clinique pour évaluer le volume des ventricules cérébraux. Toutefois une évaluation correcte dans les conditions pathologiques implique une bonne connaissance des données morphométriques du sujet normal. Pour établir ces données sur « le sujet normal », nous avons étudié les coupes obtenues en IRM chez 38 sujets apparemment indemnes de toute pathologie; nous avons calculé le volume ventriculaire dans chaque cas en utilisant des méthodes mises au point auparavant dans notre laboratoire. Les résultats ont été ensuite comparés avec ceux obtenus par d'autres études utilisant soit des moules ventriculaires, soit des coupes tomographiques computérisées. Le volume ventriculaire total moyen chez 38 sujets est de 17,4 cm3, mais il est chez les sujets masculins de 16,3 cm3 et chez les sujets de sexe féminin de 18 cm3. Une corrélation faible mais significative a été trouvée entre l'âge du sujet et le volume ventriculaire, étant entendu que la taille du ventricule augmente avec l'âge.
    Notes: Summary Accurate volume determination of the encephalic ventricles is of importance in several clinical conditions, including Alzheimer's presenile dementia, schizophrenia, and benign intracranial hypertension. Previous studies have investigated the accuracy with which magnetic resonance imaging (MRI) can be used in clinical practice to evaluate the encephalic ventricles. However, adequate evaluation of pathological conditions depends on a sufficient amount of morphometric data from normal subjects. To begin establishing this data base for “normal” subjects, we evaluated the MRI scans of 38 subjects found to have no apparent pathology and calculated the ventricular volume in each case by using methods previously developed in our laboratory. The results were then compared with published volumes determined from studies that used either ventricular casts or computerized tomographic scans. The average total ventricular volume for all 38 subjects was 17.4 cm3, while that for males was 16.3 cm3 and that for females was 18.0 cm3. A small but significant correlation was found between age of subject and ventricular volume, with ventricular size increasing with age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01623707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    A correlative study of MR images and cryo-sections of the neonatal hip (1990)
    Springer
    Surgical and radiologic anatomy 12 (1990), S. 43-51 
    Details
    ISSN: 1279-8517
    Keywords: Cryosections ; Magnetic resonance imaging ; Neonatal hip anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé L'anatomie complexe de la hanche du nouveau-né est souvent difficile à illustrer. Récemment, l'IRM a été utilisée pour étudier la hanche normale et pathologique du nouveau-né. Nous avons corrélé des explorations IRM de la hanche d'un enfant mort-né avec des cryosections faites dans divers plans. La technique de coloration de Mallory-Cason a été utilisée pour montrer le détail des structures anatomiques de la hanche normale. Dans ce travail l'IRM s'est avérée un excellent moyen d'exploration de l'anatomie de la hanche.
    Notes: Summary The complex anatomy of the neonatal hip is often difficult to image. Recently, magnetic resonance imaging (MRI) has been used to evaluate the normal and abnormal neonatal hip. We correlated the MRI scans of the hip of a newborn cadaver with multiplanar cryo-sections stained according to Mallory-Cason, to detail the anatomic structures of the normal hip joint space. In our experience, MRI was shown to provide excellent depiction of hip anatomy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02094125
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Double thoracic drainage of a left inferior vena cava (1990)
    Springer
    Surgical and radiologic anatomy 12 (1990), S. 225-227 
    Details
    ISSN: 1279-8517
    Keywords: Venae cavae, abnormalities ; Azygos vein ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les auteurs rapportent un cas de veine cave inférieure gauche avec un drainage hémiazygos puis azygos préférentiel associé à un drainage accessoire par la veine intercostale supérieure gauche. Cette malformation congénitale exceptionnelle entrant dans le cadre d'un syndrome polysplénique a été étudiée par cavographie, tomodensitométrie et imagerie par résonance magnétique.
    Notes: Summary The authors report a case of left IVC with a preferential hemiazygos-azygos drainage associated with an accessory left superior intercostal vein drainage. This exceptional congenital malformation which finds its place in polysplenia was studied by cavography, CT and MR imaging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01624528
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Comparative study between ultrasound, computed tomography, intra-arterial digital subtraction angiography, and magnetic resonance imaging in the differentiation of tumors of the liver (1990)
    Springer
    Abdominal imaging 15 (1990), S. 102-106 
    Details
    ISSN: 1432-0509
    Keywords: Liver tumors ; Ultrasound ; Magnetic resonance imaging ; Angiography ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Forty-one patients with liver tumor have been evaluated with ultrasound (US), computed tomography (CT), intra-arterial digital subtraction angiography (IA-DSA), and magnetic resonance imaging (MRI) in order to establish the accuracy of each technique. In group A (24 patients), in which all four imaging modalities were performed, our results show that MRI detected all hemangiomas (25/25) compared to 22/25, 21/25, and 20/25 with US, CT, and IA-DSA, respectively. No difference between the various methods was seen in the case of hepatoma. Finally, in the patients with metastases, all four techniques had the same sensitivity (100%) but the specificity of MRI was also 100%, compared to 33% for IA-DSA and 66% for US and CT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01888749
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Imaging of congenital esophageal cysts in adults (1990)
    Springer
    Abdominal imaging 15 (1990), S. 279-281 
    Details
    ISSN: 1432-0509
    Keywords: Congenital esophageal cysts, adults ; Computed tomography ; Ultrasound, endoscopic ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The radiologic imaging of esophageal cysts (EC) in adults is described. These rare cysts, often detected incidentally on routine chest radiographs, seldom produce symptoms, but they may cause precordial sensations, arrhythmias, and dysphagia. They may also bleed and become malignant. As surgical excision is the treatment of choice, the preoperative diagnosis must be exact. For this, magnetic resonance imaging (MRI) or endoscopic ultrasound seem to be the imaging methods of choice even if a plausible diagnosis can be advanced on computed tomography (CT). Chest x-ray or esophagus roentgenogram have little differential diagnostic value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01888796
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    Mosaic pattern of encapsulated hepatocellular carcinoma: Correlation of magnetic resonance imaging and pathology (1990)
    Springer
    Abdominal imaging 15 (1990), S. 238-240 
    Details
    ISSN: 1432-0509
    Keywords: Liver, neoplasms ; Hepatocellular carcinoma ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Internal architecture of an encapsulated hepatocellular carcinoma (HCC) was studied with magnetic resonance imaging and histologic correlation. The capsule of HCC showed low intensity relative to liver on both T1- and T2-weighted images. The T1-weighted images were superior to the T2-weighted images in delineating the capsule of HCC. The tumor showed a mosaic pattern, which was a configuration composed of multiple compartments of different intensities, reflecting viable tumor nodules and a necrotic portion. Viable tumor nodules, composed of trabeculae of polygonal cells resembling the normal liver cell with well-formed sinusoids, showed low intensity relative to liver on T1-weighted images and high intensity on T2-weighted images. The necrotic portion, composed of coagulation of amorphous, thick eosinophilic material without hemorrhage or inflammatory reaction, showed low intensity relative to liver on both T1- and T2-weighted images. The T2-weighted images were superior to the T1-weighted images in demonstrating the mosaic pattern of HCC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01888784
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Gadolinium-DTPA enhanced MR imaging in tuberous sclerosis (1990)
    Springer
    Neuroradiology 31 (1990), S. 492-497 
    Details
    ISSN: 1432-1920
    Keywords: Tuberous sclerosis ; Magnetic resonance imaging ; Computed tomography ; Gadolinium-DTPA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ten patients with clinical tuberous sclerosis were examined with CT and MR imaging, before and after IV contrast in order to determine the role of Gd-DTPA. Gd-DTPA enhancement occured in eleven subependymal nodules which did not enhance on CT after IV contrast. As illustrated by previous CT and pathologic observations and related to the histologic similarity of the subependymal nodules and giant-cell astrocytomas, these hyperintense nodules could represent active lesions with the potential to evolve. Four giant-cell astrocytomas were detected both with CT and Gd-DTPA-enhanced MRI; tumor conspicuity and size assessment were improved by postcontrast MRI in two cases. No cortical tuber or heterotopic cluster enhanced; T2-weighted sequences therefore remain necessary for their detection. If pre and post-Gd-DTPA T1-and T2-weighted imaging is negative, CT is clearly the most sensitive modality in the detection of the small calcified subependymal nodules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00340129
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    MR imaging of wallerian degeneration in the human brain stem after ictus (1990)
    Springer
    Neuroradiology 32 (1990), S. 191-195 
    Details
    ISSN: 1432-1920
    Keywords: Cerebral infarction ; Cerebral hemorrhage ; Brain stem ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Magnetic resonance (MR) imaging of wallerian degeneration in the brain stem was studied in 30 hemiplegic patients within 12 months of ictus. As early as 25 days after the ictus, decreased signal intensities on proton-density (PD)-weighted images were observed in the brain stem ipsilaterally. This hypointensity gradually approached an isointense stage during 70–80 days after the ictus, abnormal intensities were not detected in any pulse sequence. We termed this phenomenon “Fogging effect of wallerian degeneration”. In later stages, at least 81 days after the ictus, increased signal intensities on T2-weighted images, with or without decreased signal intensities on T1-weighted images, were observed in the brain stem, ipsilaterally. Finally, at least six months after the ictus, mild shrinkage of the ipsilateral brain stem was newly detected on the T1-weighted images. MR imaging has proven to be a sensitive diagnostic modality for evaluating wallerian degeneration in the brain stem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00589109
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    A follow-up study by CT and MRI in 3 cases of Japanese encephalitis (1990)
    Springer
    Neuroradiology 32 (1990), S. 215-219 
    Details
    ISSN: 1432-1920
    Keywords: Japanese encephalitis ; Sequelae ; X-ray computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A follow-up study by CT and MRI in 3 cases of Japanese encephalitis (JE) was performed. Neurologically dementia, forced laughing, tetraplegia and parkinsonism were observed as sequelae. In the CT and MR scans about 3 years after the onset of JE, low-density areas (LDAs) or abnormal signal intensities had remained in the thalamus and basal ganglia. The abnormalities were also found in the brain stem. When the main lesions shown by CT and MRI were compared with those of the acute stage, T2-weighted MRI clearly revealed multiple small areas with high signal intensities, although those in the acute stage had shown diffuse abnormal signals. These findings may be useful in helping to identify JE a long time after the onset.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00589115
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Focal pachygyria with unusual vascular anomaly (1990)
    Springer
    Neuroradiology 32 (1990), S. 237-240 
    Details
    ISSN: 1432-1920
    Keywords: Pachygyria ; Vascular anomaly ; Perfusion failure ; Magnetic resonance imaging ; Neuropathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A case of focal pachygyria with an unusual vascular anomaly is reported. Preoperative magnetic resonance imaging demonstrated few and broad gyri, and an abnormally thickened cortex of the right frontal lobe. In addition, T2-weighted imaging showed a high intensity lesion beneath the thickened cortex. In the pachygyric cortex, the peripheral portions of the arteries were tortuous and irregularly dilated, and prominent deep medullary veins were found draining into the subependymal veins. Histological examination revealed a decreased number of neurons with no tendency towards lamination, and degenerative changes with gliosis in the white matter. These findings suggest that the etiology of this anomaly may be gradual perfusion failure restricted to the territory of the anomalous vessels through the period of neuronal migration to the post-migratory, perinatal stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00589120
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    MRI of radiation induced spinal cord glioma (1990)
    Springer
    Neuroradiology 32 (1990), S. 331-333 
    Details
    ISSN: 1432-1920
    Keywords: Radiation induced glioma ; Magnetic resonance imaging ; Spinal cord ; Hodgkin's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Radiation induced neoplasms of the spinal cord are rare lesions. This report details the MR evaluation of a patient with radiation induced astrocytoma of the cervical cord. The diagnosis of second primary neoplasm should be considered in patients with prior radiation therapy when MRI demonstrates an intramedullary lesion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00593057
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    The clinical applications of echo planar imaging in Neuroradiology (1990)
    Springer
    Neuroradiology 32 (1990), S. 367-370 
    Details
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Echo planar ; Brain ; Spine ; High spped ; Fast imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ultra high speed echo-planar imaging gives an imaging time typically of the order of a few minutes, facilitating throughput, improving patient tolerance and allowing real time dynamic studies. A complete two dimensional image may be aquired in a single shot lasting between 64 and 128 ms. In echo planar imaging the whole of k-space is sampled as a continuous trajectory. By a rapidly switched Gy frequency encoding gradient, a train of gradient echoes is formed, each corresponding to a line in the k plane. Variable degrees at T2- or T1-weighting can be produced by methods outlined. High quality 128×128 transverse axial inversion recovery images of 5–10 mm thickness are obtained in 128 ms plus the inversion time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588470
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Cine MR in the evaluation of normal and abnormal CSF flow: intracranial and intraspinal studies (1990)
    Springer
    Neuroradiology 32 (1990), S. 371-391 
    Details
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Cerebrospinal fluid flow ; Hydrocephalus ; Spinal cord cyst ; Cine-MR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Evaluation of intracranial and intraspinal CSF flow was accomplished by the use of cardiac gated gradient echo magnetic resonance (MR) technique. Normal patterns of pulsatile flow within the ventricles, cisterns and cervical subarachnoid space were established by this technique and these observations were compared to prior description of CSF flow. With systole there is downward (caudal) flow of CSF in the aqueduct of Sylvius, the foramen of Magendie, the basal cisterns and the dorsal and ventral subarachnoid spaces while during diastole, upward (cranial) flow of CSF in these same structures is seen. The relationships between the cardiac cycle and the CSF pulsations are demonstrated on both magnitude reconstruction and phase reconstruction MR images. Calculations of actual fluid velocity within CSF containing spaces can be obtained from the phase reconstruction images and holds promise for a more accurate analysis of CSF flow. In conditions which result in alterations of flow, cine MR dramatically shows either obstruction or excessively turbulent flow within the CSF pathways. The site of obstructed flow whether in the third ventricle, aqueduct, fourth ventricle, or subarachnoid space can be appreciated by changes in or absence of the normal hypointense signal. Cystic cord lesions such as congenital syringohydromyelia and posttraumatic spinal cord cysts may show pulsatile flow of CSF, a fact which can relate to progressive enlargement of these cysts. The distinction between myelomalacia and cyst formation in the cord is facilitated by the technique. Although the use of cine MR for the analysis of CSF flow is in its infancy, our experience indicates that this technique is useful in a wide range of pathological conditions including, but not limited to, conditions resulting in hydrocephalus or cystic cord lesions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588471
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Visualization of isolated trigeminal nerve invasion by lymphoma using Gadolinium-enhanced magnetic resonance imaging (1990)
    Springer
    Neuroradiology 32 (1990), S. 531-532 
    Details
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Trigeminal neuropathy ; Lymphoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 50-year-old man with active histiocytic lymphoma for 12 years developed an isolated right trigeminal neuropathy. Initial evaluation with head computed tomography, X-rays of the skull base, bone scan, and cerebrospinal fluid analysis including cytology were normal. Gadolinium-enhanced magnetic resonance imaging (MRI) showed enlargement of the proximal third of the right trigeminal nerve. Gadolinium-enhanced MRI can be useful for the early demonstration of cranial nerve invasion by lymphoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426474
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Neuroradiological examination of thoracic radiculo-myelopathy due to ossification of the ligamentum flavum (1990)
    Springer
    Neuroradiology 32 (1990), S. 38-42 
    Details
    ISSN: 1432-1920
    Keywords: Spinal cord compression ; Computed tomography ; Magnetic resonance imaging ; Ossification of ligamentum flavum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sixteen cases of thoracic radiculomyelopathy due to ossification of the ligamentum flavum (OLF) were analyzed. The patients ranged in age from 39 to 78 years (average 57 years). There were 13 men and 3 women. A significant predilection of OLF for the lower thoracic spine (T9/10, T10/11, T11/12) was noticed. Plain X-ray of the thoracic spine and multidirectional tomography could give important information about the site of ossification. Computed tomography with the intrathecal injection of the water-soluble contrast material clearly demonstrated the ossification and the degree of compression of the spinal cord. The disadvantages of using computed tomography for diagnosing OLF included the necessity for the scan level to be previously decided by other methods because computed tomography of the entire spine was impractical. Magnetic resonance imaging was performed in 14 patients and gave important information about OLF and the compression of the spinal cord. The combination of MRI and computed tomography seems the most useful for the precise diagnosis of OLF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00593939
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Sodium-23 magnetic resonance brain imaging (1990)
    Springer
    Neuroradiology 32 (1990), S. 416-420 
    Details
    ISSN: 1432-1920
    Keywords: Brain ; Sodium ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This is a review of recent work in23Na MR imaging. The main emphasis of recent papers has been pulse sequences that, with appropriate postprocessing, give images of the fast, slow, and intermediate components of T2 decay. The assignment of compartmental designation to the T2 component remains a problem except for homogeneous structures easily identifiable anatomically (ventricles, superior sagittal sinus, globe of the eye). Compartmental distribution of sodium is described. The predominance of the interstitial and plasma compartment, the invisibility of part of the intracellular sodium, and the difficulty in imaging the very fast T2 component of visible intracellular sodium make the usual Na spin-echo image essentially an image of the interstitial and plasma space. Use of super paramagnetic iron oxide coupled to dextran as a contrast medium may help to identify the plasma compartment. Because the usual Na MR images are essentially interstitial and plasma images, our own interest is in observing functional changes in these compartments. Another proposed application is the detection of the very fast T2 component in brain tumors to aid in defining tumor grade and extent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588475
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    Multiple slice FLASH imaging: An improved pulse sequence for contrast enhanced MR brain studies (1990)
    Springer
    Neuroradiology 32 (1990), S. 474-480 
    Details
    ISSN: 1432-1920
    Keywords: FLASH ; Spin-echo technique ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A multisclice gradient echo sequence (FLASH) was compared with a conventional spin-echo (SE) technique with regard to its value for contrast enhanced brain studies. In 50 patients with contrast enhancing intracranial lesions, MR studies (0.5 Tesla MR tomograph) were performed with SE images (SE 400/30; four images/3.4 min) and FLASH scans (FLASH 315/14, 90°; 15 images/1.4 min) before and after Gd-DTPA. Based on visual and quantitative assessment diagnostic results of postcontrast SE- and FLASH images were equivalent with respect to contrast enhancement, lesion/brain-contrast, lesion/edema-contrast, and lesion delineation. Although image quality generally was excellent on postcontrast FLASH images, susceptibility artifacts were more severe on FLASH scans than on SE images. However, with the exception of postoperative patients with artifacts due to metal remains, diagnostic information was not decreased by artifacts on postcontrast FLASH images. In conclusion, because of the clearly higher efficiency of the multisclice FLASH technique, this pulse sequence offers the opportunity to speed up contrast enhanced brain imaging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426458
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Mandibular nerve: MR versus CT about 10 proved unusual tumors (1990)
    Springer
    Neuroradiology 32 (1990), S. 492-496 
    Details
    ISSN: 1432-1920
    Keywords: Nerves, trigeminal ; Parapharyngeal space ; Masticator space ; Magnetic resonance imaging ; Cavernous sinus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 10 patients with symptoms of mandibular neuralgia formed the basis of this study. They were studied by both enhanced CT and MRI. MRI, better than CT, easily permits distinction between intrinsic and extrinsic lesions and detects involvement of the cavernous sinus and meninges. Morever, because of its multiplanar imaging capability, and ability to portray exquisite anatomic details and characteristic tissue signal intensity, MRI is helpful in the evaluation of tumor involvement for biopsy and preoperative planning for these deep tumours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426462
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Intraventricular choroid plexus “arachnoid” cyst (1990)
    Springer
    Neuroradiology 32 (1990), S. 523-525 
    Details
    ISSN: 1432-1920
    Keywords: Arachnoid cyst ; Lateral ventricle ; choroid plexus ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A young women presented with chronic headaches associated with a cyst of the right lateral ventricle. The diagnosis of intraventricular so-called “arachnoid” cyst was supported by CT scan, MRI and stereotactic puncture. MRI was of great value for demonstrating that the cyst was located within the lateral ventricule, that it was delinated by a thin wall adherent to the choroid plexus and that the cyst content was CSF-like.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426471
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Gd-DTPA enhanced MR imaging in intracranial tuberculosis (1990)
    Springer
    Neuroradiology 32 (1990), S. 19-25 
    Details
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Tuberculosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-six patients with intracranial tuberculosis (Tb) (10 with acute meningitis, 5 with chronic meningitis, 5 with meningitic sequelae and 6 with localized tuberculoma(s) were examined with MR before and after Gd-DTPA enhancement (0.1 mmol/kg), using 2.0T superconducting unit, and the images were retrospectively analyzed and compared with CT scans. Without Gd-DTPA enhancement, the MR images were generally insensitive to detection of active meningeal inflammation and granulomas. The signal intensity of granulomas was usually isointense to gray matter on both T1- and T2-weighted images, whether they were associated with diffuse meningitis or presented as localized tuberculoma(s). A few granulomas showed focal hypointensity on T2-weighted images. Calcifications seen on CT of the meningitic sequelae group usually appeared markedly hypointense on all spin-echo sequences. On Gd-DTPA enhanced T1-weighted images, abnormal meningeal enhancement indicating active inflammation was conspicuous, and the granulomas often appeared as conglomerated ring-enhancing nodules, which seems to be characteristic of granulomas. Thin rim enhancement around the suprasellar calcifications were observed in two out of 5 patients with meningitic sequelae. Compared with CT, MR detected a few more ischemic infarcts, hemorrhagic infarcts, meningeal enhancement and granulomas in the acute meningitis group, but missed small calcifications in the basal cisterns well shown on CT in the sequelae group. Otherwise, MR generally matched CT scans. MR imaging appears to be superior to CT in evaluation of active intracranial Tb only if Gd-DTPA is used, while CT is better than MR in evaluating meningitic sequelae with calcification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00593936
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    Magnetic resonance evaluation of severe neurological disorders in eclampsia (1990)
    Springer
    Neuroradiology 32 (1990), S. 47-49 
    Details
    ISSN: 1432-1920
    Keywords: Eclampsia ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A patient with eclampsia and severe but reversible neurological disorders is presented. Initial magnetic resonance imaging (MRI) revealed multiple hyperintense areas throughout the brain and brainstem that were consistent with ischemia and/or edema. Despite these diffuse lesions extending to the brainstem, the patient made a progressive neurological recovery and a follow-up MRI on day 21 demonstrated complete resolution of the hyperintense foci. MRI abnormalities were found to correlate more closely with clinical and electrophysiological data than CT findings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00593941
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    The “dense artery sign” — major cerebral artery thromboembolism demonstrated by computed tomography (1990)
    Springer
    Neuroradiology 32 (1990), S. 98-103 
    Details
    ISSN: 1432-1920
    Keywords: Cerebral infarction ; Thrombembolism ; Computed tomography ; Density quantification ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 4 years review of high resolution thin slice (3–5 mm) computed tomography performed within 24 h after cerebral infarction revealed increased density in a major cerebral artery segment in 28 patients. Arteries affected were the vertebral and basilar artery in 6 and 8 patients, the sphenoid course of the middle cerebral artery in 13 cases and the extracranial internal carotid artery in 1 patient. In 35.7% of cases the so called “dense artery sign” provided earliest evidence of the ensuing infarction documented by CT controls in most patients. Angiography carried out in 8 patients, density caculations in the course of the affected vessel and resolution of the increased density on subsequent CT examinations suggest thrombembolism as the most likely etiology. In the clinical setting of acute stroke increased artery density encompassing the entire vessel diameter may serve as an early indicator of major cerebral artery occlusion and prompt angiographic investigation of a lesion potentially amenable to lysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588557
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    Joubert syndrome: a clinico-radiological study (1990)
    Springer
    Neuroradiology 31 (1990), S. 502-506 
    Details
    ISSN: 1432-1920
    Keywords: Joubert syndrome ; Developmental abnormalities ; Brain ; CT ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A characteristic malformation of the cerebellum, including dysgenesis of the vermis and enlargement of the fourth ventricle was observed on computed tomography (CT) in 16 children on review of our consecutive material. Seven of these children underwent magnetic resonance imaging (MRI) which showed hypoplasia of the brainstem in addition to cerebellar vermian dysgenesis. One child had, in addition, dysgenesis of the corpus callosum. All these children were developmentally delayed, and many had neonatal breathing abnormalities, congenital retinal dystrophy and supranuclear ocular motor abnormalities. Joubert's syndrome should be suspected in children in whom dysgenesis of the cerebellar vermis and hypoplasia of the brainstem is shown on CT or MRI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00340131
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    Comparing the cost of spinal MR with conventional myelography and radiculography (1990)
    Springer
    Neuroradiology 32 (1990), S. 124-136 
    Details
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Spinal ; Comparison with myelography, radiculography ; Costs ; Effectiveness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary All spinal magnetic resonance imaging examinations carried out during a three month period were analysed retrospectively in order to determine the clinical reasons for the scan requests. Technical details of the examinations they received and the clinical profiles formed a data set which revealed 10 separate “Clinical groups” for management purposes. Hardware, salary and expendables were costed as though the imaging unit had been sited within a National Health Service radiology department. A spread sheet was designed capable of calculating costs per patient for a variety of types of working week and of different staffing structures, sensitive to the mixture of clinical groups referred for examination. The spreadsheet also accomodated straight line depreciation for hardware value and interest rates for borrowed capital. A second, prospectively observed, sample of spinal MR examinations was used to improve the accuracy of the timing of the length of patient examinations. Costs were compared with those for patients submitted for myelography and radiculography at the adjacent hospital during the same period. The comparison indicated that spinal MR was less costly than myelography and radiculography. The most important element of the extra cost of myelography related to the need to admit patients to hospital for at least one night for this examination because of the likelihood of headache and other common (though usually minor) complications following lumbar puncture and/or the injection of contrast medium. From the limited information that it was possible to obtain in the period of follow up, it appeared that MR had either been superior or equivalent to myelography or radiculography in all the clinical groups of patients where both could be tested. There were a number of groups in which no myelograms had been requested, presumably because clinical suspicions had pointed toward conditions like tumours, developmental abnormalities and demyelinating diseases in which neurologists and neurosurgeons have already made up their minds about the superiority of MR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588562
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    Negative scintigraphy with positive magnetic resonance imaging in bone metastases (1990)
    Springer
    Skeletal radiology 19 (1990), S. 113-116 
    Details
    ISSN: 1432-2161
    Keywords: Magnetic resonance imaging ; Metastases ; Scintigraphy ; Radionuclide ; Bone scan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report three patients with known primary tumor in whom radionuclide skeletal imaging for metastatic disease was normal with or without clinical symptomatology referable to this area. Magnetic resonance imaging (MRI) of the spine demonstrated focal areas of abnormal signal intensity in the vertebral bodies of these patients. In all three patients, biopsy confirmed metastatic disease. All the patients received radiation or chemotherapy depending upon the etiology. These preliminary data suggest that MR imaging may be useful in evaluating patients with known primary tumor in whom clinical suspicion persists despite a negative radionuclide bone scan.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197616
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging in acute and chronic rotator cuff tears (1990)
    Springer
    Skeletal radiology 19 (1990), S. 109-111 
    Details
    ISSN: 1432-2161
    Keywords: Magnetic resonance imaging ; Acute and chronic rotator cuff tears
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance imaging has been assessed in patients with acute rotator cuff tears and normal radiographs (9 cases) and those with chronic tears and changes of cuff arthropathy (9 cases). All images were obtained using a low field strength system (FONAR 0.3 T). Particular attention was placed on the appearances of the tendon and the cuff muscles themselves. Six complete acute tears were clearly identified, but MRI failed to demonstrate two partial tears. Muscle bulk was preserved in all patients in this group. In contrast, all patients with cuff arthropathy had complete tears of the supraspinatus tendon with marked tendon retraction and associated muscle atrophy: these changes precluded primary surgical repair. MRI should be used to assess muscle atrophy preoperatively in those patients with acute tears. When plain radiographs demonstrate cuff arthropathy, the MRI appearances are predictable and primary repair is unlikely to be successful. Further imaging is therefore not indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197615
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging in the evaluation of sequelae after tibial plateau fractures (1990)
    Springer
    Skeletal radiology 19 (1990), S. 127-129 
    Details
    ISSN: 1432-2161
    Keywords: Tibial fractures ; Tibial plateau ; Articular depression ; Fibro-cartilage ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Nine knees with persistent radiographic depression of the articular surface after tibial plateau fractures treated by traction and early knee motion were examined using magnetic resonance imaging (MRI). The MRI examinations demonstrated that the radiographic bone defects were filled up with different tissues, which we interpreted as cartilage, fibrous tissue and synovial plica. The type of tissue in the bone defect did not seem to affect the functional capabilities of the knee. However, a demonstrable thin cover of tissue, with the signal-intensity of cartilage, over the defect, seemed to be associated with an excellent functional result.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197620
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    Musculoskeletal haemangiomas: comparison of MRI with CT (1990)
    Springer
    Skeletal radiology 19 (1990), S. 251-258 
    Details
    ISSN: 1432-2161
    Keywords: Musculoskeletal haemangiomas ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI and CT findings were reviewed from 11 patients with musculoskeletal haemangiomas. With MRI, morphological characteristics and extent of haemangiomas were optimally demonstrated on T2-weighted spin echo scans. High-resolution contrast-enhanced CT provided equivalent information regarding lesional characteristics and extent for small, localized haemangiomas. In CT evaluation of the extent of large haemangiomas, the radiation dose, transaxial scan plane, amount of intravenous contrast medium required and the necessity for correct timing of post-contrast scans became limiting factors. For such lesions, particularly those extending into the trunk, MRI supplemented by a plain radiograph is the optimum method of evaluation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191666
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    MRI demonstration of hypertrophic articular cartilage repair in osteoarthritis (1990)
    Springer
    Skeletal radiology 19 (1990), S. 335-339 
    Details
    ISSN: 1432-2161
    Keywords: Magnetic resonance imaging ; Knee ; Osteoarthritis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Transection of the anterior cruciate ligament in the dog produces changes in the unstable joint typical of osteoarthritis, although full-thickness cartilage ulceration is rare. Information concerning the late fate of the cartilage after transection is meager. In the present study magnetic resonance imaging (MRI) was used to evaluate cartilage abnormalities 3 years after transection. Plain radiographs of the osteoarthritic and contralateral knees were obtained serially. MRI was performed 3 years after anterior cruciate ligament transection, at which time all three animals exhibited knee instability. Radiographs of the osteoarthritic knees showed osteophytes and subchondral sclerosis with progression between 2 and 3 years. On MRI, articular cartilage margins in the knee were indistinct, and the cartilage was thicker than that in the contralateral knee (maximum difference= 2.7 mm). This increase in thickness is consistent with biochemical data from dogs killed up to 64 weeks after creation of knee instability, which showed marked increases in cartilage bulk and in proteoglycan synthesis and concentration. The findings emphasize that increased matrix synthesis after anterior cruciate ligament transection leads to functional cartilage repair sustained even in the presence of persistent alteration of joint mechanics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193086
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    Panhypopituitarism without diabetes insipidus: Magnetic resonance imaging of pituitary stalk transection (1990)
    Springer
    European journal of pediatrics 149 (1990), S. 235-236 
    Details
    ISSN: 1432-1076
    Keywords: Panhypopituitarism ; Magnetic resonance imaging ; Empty sella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 13 year 2 month old girl was referred with panhypopituitarism without diabetes insipidus. Magnetic resonance imaging demonstrated transection of the pituitary stalk, a hypoplastic pituitary gland, and the presence of an ectopic neurohypophysis located at the proximal stump of the transected stalk.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02106279
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    Criss-cross heart evaluated by colour Doppler echocardiography and magnetic resonance imaging (1990)
    Springer
    European journal of pediatrics 149 (1990), S. 523-525 
    Details
    ISSN: 1432-1076
    Keywords: Criss-cross heart ; Two-dimensional echodardiography ; Colour Doppler echocardiography ; Magnetic resonance imaging ; Congenital heart disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two-dimensional colour Doppler echocardiography was performed on a 1-month-old male infant with criss-cross heart, double outlet right ventricle, ventricular septum defect and pulmonary stenosis. Complex structural abnormalities were suspected after two-dimensional echocardiography (2-D echo) and confirmed by colour Doppler and magnetic resonance imaging (MRI). We stress that the blood streams in the ventricular inflow tracts revealed by colour Doppler and the spatial relationships of the cardiac segments disclosed by MRI are essential to make an accurate non-invasive diagnosis of this complex malformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01957683
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    Giant aneurysm causing frontal lobe syndrome (1990)
    Springer
    Journal of neurology 237 (1990), S. 47-50 
    Details
    ISSN: 1432-1459
    Keywords: Giant aneurysm ; Frontal lobe syndrome ; Cranial computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 67-year-old patient with a completely thrombosed giant aneurysm of the anterior communicating artery is described. The only neurological findings were a disturbance of stance and gait and slight bilateral grasp reflexes. He had had the features of a frontal lobe psychotic syndrome for more than 12 years. Computed tomography demonstrated a primarily hyperdense calcified suprasellar space-occupying lesion. Magnetic resonance imaging proved valuable in establishing the correct diagnosis, which was confirmed post mortem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00319669
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Sarcoidosis of the cauda equina: a report of three cases (1990)
    Springer
    Journal of neurology 237 (1990), S. 424-426 
    Details
    ISSN: 1432-1459
    Keywords: Sarcoidosis ; Cauda equina ; Laminectomy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Three cases of sarcoidosis of the cauda equina are presented. In two there was no previous history suggestive of sarcoidosis and the presentation was one of a painful flaccid paralysis; in these the diagnosis was made after myelography and laminectomy with subsequent histology. The third patient had a previous diagnosis of lupus pernio and magnetic resonance imaging (MRI) was used to aid diagnosis. Only two previous cases have been reported of sarcoidosis presenting in the cauda equina with no other systemic manifestations. This is the first report of the use of MRI in sarcoidosis of the lower meninges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314734
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    The development of infratentorial atrophy in patients with idiopathic cerebellar ataxia of late onset: a CT study (1990)
    Springer
    Journal of neurology 237 (1990), S. 420-423 
    Details
    ISSN: 1432-1459
    Keywords: Infratentorial atrophy ; Idiopathic cerebellar ataxia ; Olivopontocerebellar atrophy ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development of infratentorial atrophy in six patients suffering from idiopathic cerebellar ataxia of late onset was studied by a retrospective evaluation of consecutive computed tomography (CT) scans. Four patients had evidence of olivopontocerebellar atrophy (OPCA) both on clinical testing and magnetic resonance imaging (MRI). In these four patients, atrophy of the cerebellum and brain stem became visible at the same time and progressed in a roughly parallel manner, whereas in the remaining two the brain stem was left intact. In all patients with OPCA, definite brain-stem atrophy was visible earlier than the appearance of non-cerebellar clinical symptoms. The present data suggest that CT investigations at regular intervals may be of prognostic value in cerebellar ataxias.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314733
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    The hemimedullary syndrome: case report and review of the literature (1990)
    Springer
    Journal of neurology 237 (1990), S. 208-212 
    Details
    ISSN: 1432-1459
    Keywords: Hemimedullary syndrome ; Intracranial vertebral artery occlusion ; Magnetic resonance imaging ; Literature review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Hemi-infarction of the medulla causes the clinical constellation of symptoms and signs of both the lateral and medial medullary syndromes and nearly always results from occlusion of an intracranial vertebral artery. In the case reported here, with a clinical diagnosis of hemimedullary syndrome, the expected infarction was imaged by magnetic resonance. A review of the literature confirms that the hemimedullary syndrome, in which both medial and lateral syndromes occur simultaneously, is extremely rare, since it yielded only two previous cases with adequate anatomical confirmation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314596
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Cure of a man with solitary abscess of the brain-stem (1990)
    Springer
    Journal of neurology 237 (1990), S. 265-266 
    Details
    ISSN: 1432-1459
    Keywords: Brain-stem abscess ; Antibiotics ; Stereotactic aspiration ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 25-year-old man with lung abscess and signs of an abscess in the rostral brain-stem was cured by large doses of antibiotics and stereotactic aspiration of the abscess.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314632
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Central pontine myelinolysis associated with low potassium levels in alcoholism (1990)
    Springer
    Journal of neurology 237 (1990), S. 275-276 
    Details
    ISSN: 1432-1459
    Keywords: Central pontine myelinolysis ; Serum electrolytes ; Magnetic resonance imaging ; Vitamin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two patients with chronic alcohol abuse and central pontine myelinolysis are described. One developed a Korsakoff syndrome 2 days before admission to our hospital and the other showed signs of a incipient delirium without Korsakoff syndrome. Diagnosis of incipient central pontine myelinolysis was based on acute brain-stem dysfunction, serum electrolyte disturbances, malnutrition with vitamin B1 (thiamine), B6 (pyridoxine) and B12 (cyanocobalamine) deficiency in combination with typical neuroradiological findings. Hypokalaemia but no disturbance in serum sodium levels was found in both patients. After correction of hypokalaemia and vitamin deficiency the patients showed complete recovery of neurological and neuropsychological function. The findings are interpreted as suggesting that disturbances in serum potassium levels as well as rapid correction of hyponatraemia may be associated with pontine swelling and dysfunction which, if undetected, leads to central pontine myelinolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314635
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Acute- and insidious-onset myelopathy of undetermined aetiology: contribution of paraclinical tests to the diagnosis of multiple sclerosis (1990)
    Springer
    Journal of neurology 237 (1990), S. 171-176 
    Details
    ISSN: 1432-1459
    Keywords: Multiple sclerosis ; Myelopathy ; Magnetic resonance imaging ; Evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Brain magnetic resonance imaging (MRI), multimodality evoked potentials (EPs) and cerebrospinal fluid examination were performed in 42 patients with myelopathy of undetermined aetiology in order to detect abnormalities usually related to multiple sclerosis (MS). Patients were divided into three groups: insidious-onset myelopathy with only motor signs (group A; 11 patients), with both motor and sensory signs (group B; 18 patients) and acute-onset myelopathy (group C; 13 patients). Multiple brain MRI lesions were found in 18 patients (2 of group A, 13 of group B and 3 of group C). Another 7 patients had a single white-matter lesion. Visual EPs were abnormal in 21 and brain-stem auditory EPs in 12 patients. Paraclinical tests supported the diagnosis of MS in 25 patients (60%) by showing subclinical brain abnormalities. Oligoclonal bands were found in 16 of these 25 patients. The findings strongly suggest a diagnosis of MS in the patients of group B.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314590
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    Miller-Fisher syndrome and pontine abnormalities on MRI: a case report (1990)
    Springer
    Journal of neurology 237 (1990), S. 489-490 
    Details
    ISSN: 1432-1459
    Keywords: Miller-Fisher syndrome ; Pontine lesions ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors report a patient with Miller-Fisher syndrome in whom MRI of the brain stem showed increased signal density on T2 sequence anterior to the fourth ventricle, on the right and the left. The authors discuss the relation between these MRI abnormalities and some clinical features of the syndrome. The authors believe that the cardinal features of Miller-Fisher syndrome are due to peripheral nervous system dysfunction, but that this does not preclude a possible central nervous system involvement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314769
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    A case of chronic GM1 gangliosidosis presenting as dystonia: clinical and biochemical studies (1990)
    Springer
    Journal of neurology 237 (1990), S. 491-493 
    Details
    ISSN: 1432-1459
    Keywords: Chronic GM1 gangliosidosis ; Dystonia ; GM1 ganglioside metabolism ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Clinical and biochemical studies are reported on a 32-year-old man with GM1 gangliosidosis who presented with a slowly progressive dystonia that began when he was aged 7 years and eventually became almost totally incapacitating at the age of 35. There was only mild intellectual deterioration, but myoclonus, seizures and macular cherry-red spots were never observed. Proton-density and T2-weighted MRI scans showed symmetrical hyperintense lesions of both putamina. No increase of GM1 ganglioside was found in plasma or cerebrospinal fluid, and the metabolism of GM1 ganglioside in cultured skin fibroblasts from the patient was also almost normal, although the residual activity of GM1 ganglioside β-galactosidase activity was only 10% of normal. These findings suggest that impaired GM1 ganglioside metabolism is not present systemically as it is in the infantile and juvenile types of the disorder, but is mainly confined to the central nervous system in chronic GM1 gangliosidosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314770
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Motor dysfunction in HIV-infected patients without clinically detectable central-nervous deficit (1990)
    Springer
    Journal of neurology 237 (1990), S. 362-368 
    Details
    ISSN: 1432-1459
    Keywords: HIV infection ; Slowness of movement ; Basal ganglia disease ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Motor tests were performed in 50 HIV-infected patients in all stages according to the current CDC classification, but without any clinically evident central nervous system deficit, and the results compared with an age-matched control group. Patients were excluded from the study if there was alcohol or drug abuse, fever and/or opportunistic cerebral infection. The parameters tested were postural tremor of the outstretched hands, most rapid voluntary alternating index finger movements (MRAM) and rise time of most rapid index finger extensions (MRC). Whereas tremor peak frequencies did not differ significantly in the patients and controls, MRAM and rise times of MRCs showed significant slowing in the patient group. Morphologically, the motor test performance of the HIV-infected patients was similar to that of patients with manifest basal ganglia disease (Parkinson's, Huntington's and Wilson's diseases). MRI scans of all patients were normal. It is concluded that in HIV-infected patients there is a very early subclinical central nervous system affection, especially of the basal ganglia, which is detectable with appropriate, quantitative motor function tests. These functional abnormalities precede the structural alterations in the MRI scans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315660
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Magnetic resonance evaluation of spinal dysraphism in children (1990)
    Springer
    Child's nervous system 6 (1990), S. 161-165 
    Details
    ISSN: 1433-0350
    Keywords: Magnetic resonance imaging ; Spinal dysraphism ; Spinal cord abnormalities ; Pediatric spinal cord
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance (MR) imaging of the spine was performed as the initial imaging technique in 20 children when spinal dysraphism was suspected clinically and plain radiographs showed spina bifida. The correlation with surgical findings indicated that MR provided accurate information preoperatively in all the cases. Some unusual observations in cases with spina bifida cystica and occulta are discussed. It is concluded that plain radiograph and MR complete the preoperative radiologic evaluation of cases with spinal dysraphism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308494
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Transient focal leukoencephalopathy following intraventricular methotrexate and cytarabine (1990)
    Springer
    Child's nervous system 6 (1990), S. 231-235 
    Details
    ISSN: 1433-0350
    Keywords: Methotrexate leukoencephalopathy ; Ommaya reservoir ; Computed tomography ; Magnetic resonance imaging ; Meningeal leukemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 14-year-old boy, suffering from acute lymphoblastic leukemia with meningeal involvement, was treated with intraventricular methotrexate and cytosine arabinoside, administered via an Ommaya reservoir (OR). Three months later, right occipital headache, vomiting, and lethargy appeared. Cerebrospinal fluid specimens showed increased proteins and a right frontal slow-wave focus was evident on the EEG recording. The computed tomography scan revealed white matter hypodensity within the right frontal and rolandic regions. After injection of medium contrast, an abscesslike hyperdensity appeared, surrounding both a well-placed cannula tip and the right frontal horn of the lateral ventricle. Brain swelling and shift signs were also evident. Nine cases of focal methotrexate leukoencephalopathy have been previously reported, and in six of these there was a misplaced OR cannula tip. The focal meihotrexate leukoencephalopathy seems to be related to the neurotoxicity of the drugs administered, and may also exist with a well-placed OR cannula tip. Immediate removal of the catheter may be associated with a benign evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01850981
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    Tethered cord syndrome versus low-placed conus medullaris in an over-distended spinal cord following initial repair for myelodysplasia (1990)
    Springer
    Child's nervous system 6 (1990), S. 264-269 
    Details
    ISSN: 1433-0350
    Keywords: Tethered cord syndrome ; Low-placed conus medullaris ; Myeloschisis ; Lipomeningocele ; Magnetic resonance imaging ; Over-distended spinal cord
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present findings obtained from a total of 100 patients who had previously undergone surgery for spina bifida and whose progress had been monitored by magnetic resonance imaging (MRI) in our meningomyelocele clinic. Fourteen of these patients (14.0%) developed delayed symptom(s) of progressive spinal neurologic dysfunction. In those with myeloschisis, increase of motor deficit was the most common clinical manifestation during infancy and early childhood (mean age: 6.8 years), whereas pain on back flexion was seen in patients who were over 15 years of age (mean age: 17.3 years). MRI carried out in myeloschisis patients invariably demonstrated that the conus medullaris was in an abnormally low position, suggesting over-distension of the spinal cord. This was irrespective of whether symptom(s) developed or not and did not correlate with the initial surgical procedure (reconstructive or otherwise) used. Patients with symptom(s) were revealed by MRI to have an extremely low conus set at the spinal level of S-1 or below; neurological examination showed that the motor deficit occurred at high levels in the spine. Results from lipomeningocele patients were more erratic in terms of conus position and delayed development of neurological defects. The authors conclude: (1) that elongation of the spinal cord as an MRI finding seen postoperatively in cases of myeloschisis (radiological finding of a low-placed concus medullaris) does not necessarily imply functional disorder (tethered cord syndrome) and (2) that the pathophysiology of the late onset of progressive neurological deterioration in the spine occurring in patients who have previously undergone lipomeningocele repair may be associated with an invasive or expansile mass effect and should not always be regarded as involving tethered cord syndrome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307662
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    Magnetic resonance appearance of fibromatosis (1990)
    Springer
    Skeletal radiology 19 (1990), S. 495-499 
    Details
    ISSN: 1432-2161
    Keywords: Fibromatosis ; Desmoid tumor ; Soft-tissue tumors ; Skeletal neoplasms ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We reviewed retrospectively the magnetic resonance (MR) images of 14 soft-tissue lesions of fibromatosis (desmoid tumors) encountered in 11 patients. The lesions were typically inhomogeneous in texture and round to oval in configuration. Margins were well-defined in 78% of the lesions at presentation and were infiltrating in all recurrences. On T1-weighted spin echo MR images, the predominant signal intensity was either isointense or minimally hyperintense when compared with skeletal muscle. On T2-weighted MR images the predominant signal intensity was typically intermediate between skeletal muscle and subcutaneous fat or isointense to fat. Linear and curvilinear areas of decreased signal intensity were distributed throughout the lesions on both pulse sequences in 86% of cases. This pattern strongly suggested fibromatosis. Speculation concerning possible etiologies of this appearance are discussed, and the relevant literature on previously reported cases is reviewed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202698
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Surgical treatment of intracranial dermoid and epidermoid cysts in children (1990)
    Springer
    Child's nervous system 6 (1990), S. 66-70 
    Details
    ISSN: 1433-0350
    Keywords: Epidermoid cysts ; Dermoid cysts ; Computed tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Between 1956 and 1987 operations were performed on 36 patients below the age of 20 years for epidermoid and dermoid cysts of the central nervous system. Seventeen tumors were intracranial intradural lesions (47%): 12 were located in the supratentorial region (71%) and 5 were located in the infratentorial region (29%). Ten of these tumors (59%) were seated along the midline structures. The clinical presentation was consistent with the location of the tumors. The neuroradiological diagnosis was mostly made with the aid of pneumoencephalography, computed tomography (CT), nonionic contrast medium CT cisternography, and magnetic resonance imaging. Complete removal of the tumor contents was performed in all cases but one, although the completeness of removal of the tumor capsule could not be exactly estimated in some patients. At late follow-up only two tumor recurrences were observed. Radical removal of the tumor capsule of these congenital tumors, even when it is connected to vital neurovascular structures, seems advisable in patients who become symptomatic within the first two decades of life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307923
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    A case of “accessory falx cerebri” (1990)
    Springer
    Child's nervous system 6 (1990), S. 275-276 
    Details
    ISSN: 1433-0350
    Keywords: Dura mater ; Anatomical variation ; Magnetic resonance imaging ; Cavernous hemangioma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report on a 12-year-old boy who underwent a right frontotemporoparietal craniotomy for complete extirpation of three cavernous hemangiomas of the temporal lobe. On this occasion, an accessory dural septum was observed that spanned, in the direction of the corona, the temporo-occipital base upward to the lower pariental area. It produced a deep notch in the cortex, was supplied by a small leptomeningeal artery, and probably contained a small venous sinus. Embryological considerations and clinical relevance are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307664
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    The use of magnetic resonance imaging for the diagnosis of fetal intracranial anomalies (1990)
    Springer
    Child's nervous system 6 (1990), S. 212-215 
    Details
    ISSN: 1433-0350
    Keywords: Sonography ; Fetal ventriculomegaly ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract While fetal cranial sonography has been used for the sensitive detection of ventriculomegaly, ancillary imaging techniques may be needed for precise delineation of structural abnormalities. This report outlines the radiologic and clinical results using maternal magnetic resonance imaging (MRI) in ten patients with suspected fetal intracranial anomalies. Imaging was accomplished at 17–39 weeks gestational age, using spin-echo, a multislice technique with intramuscular morphine sulfate for sedation. In four cases, MRI significantly clarified the sonographic diagnosis, while in two cases the scan agreed with the sonographic findings. In one patient, MRI failed to image a lumbar meningomyelocele associated with the Chiari II malformation. In two patients with the Chiari II malformation, both sonography and MRI failed to delineate the anatomic pathology completely. Optimal imaging resolution was achieved in the third trimester. Four patients died in the perinatal period. All the surviving patients required shunting to treat intracranial hypertension; only two patients were meeting cognitive milestones. We conclude that due to the high incidence of multiple anomalies in the fetus with ventriculomegaly, precision in neuroradiological diagnosis is essential. MRI can be a useful adjunct to cranial sonography for the specific delineation of abnormalities of the fetal central nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01850975
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    Pathophysiology and postnatal outcome of fetal hydrocephalus (1990)
    Springer
    Child's nervous system 6 (1990), S. 338-345 
    Details
    ISSN: 1433-0350
    Keywords: Fetal hydrocephalus ; Intracranial pressure ; Magnetic resonance imaging ; Postnatal outcome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract At the National Kagawa Children's or Kobe University Hospital, 24 cases of fetal hydrocephalus were managed between 1982 and 1988. There were 8 simple, 11 dysgenetic, and 5 secondary cases of hydrocephalus, and the fetal age at diagnosis ranged between 24 and 40 weeks of gestation (average 33.4 weeks). All were diagnosed using ultrasonography, with either magnetic resonance imaging or whole-body computed tomography, additionally performed in 10 patients to determine their usefulness in evaluating the morphology. Four patients underwent transabdominal or transvaginal cephalocentesis in the prenatal period and intracranial pressure was measured during the drainage of cerebrospinal fluid in two of these. Postnatal outcome was analyzed for each type of hydrocephalus. The results suggested that in such cases the fetal brain is subjected to extremely high intracranial pressures resulting from a mixture of hydrocephalic pressure and intermittent uterine constriction. Immediately after birth, the biparietal diameter was found to be increased by an average of 7.7 mm and the hydrocephalic state was transformed into the neonatal type characterized by macrocephaly and a relatively low intracranial pressure. Overall mortality was 25% and 16 of the 24 infants underwent the postnatal shunt procedure, largely at the neonatal stage. The follow-up period varied from 4 months to 6 years (average, 25.8 months for nonfatal cases) and the mean intelligence or developmental quotient was 45.2. There were no significant differences in postnatal outcome between the three major types of fetal hydrocephalus. Findings revealed that the length of the gestation period after the diagnosis of hydrocephalus has a significant effect on outcome (P〈0.01). Based on these results, it is suggested that fetal hydrocephalus may be extremely hypertensive and that impairment of neuronal functional development accompanying its prenatal progression can be irreversible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298281
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Progressive inflammatory lesions of the brain parenchyma in localized scleroderma of the head (1990)
    Springer
    Journal of neurology 237 (1990), S. 379-381 
    Details
    ISSN: 1432-1459
    Keywords: Localized scleroderma ; Magnetic resonance imaging ; Central nervous system inflammation ; Intrathecal IgG production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A patient with localized scleroderma of the head, uveitis, and Raynaud's phenomenon presented with generalized seizures, spastic hemiparesis, and local IgG production in the cerebrospinal fluid. Magnetic resonance imaging revealed progressive cortical and subcortical brain parenchymal lesions mainly adjacent to the cutaneous and bony lesions and probably of inflammatory origin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315664
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging in motor neuron disease (1990)
    Springer
    Journal of neurology 237 (1990), S. 471-474 
    Details
    ISSN: 1432-1459
    Keywords: Amyotrophic lateral sclerosis ; Progressive muscular atrophy ; Bulbar palsy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Magnetic resonance imaging (MRI) of the brain was evaluated in 20 patients with motor neuron disease (MND) and in a control group of 11 healthy people. Bilateral increased signal areas of various sizes in the centrum semiovale, corona radiata, internal capsule, pedunculi of midbrain, pons, medulla and even in the frontal lobe, topographically related with the corticospinal tract, were found in 8 out of 20 patients. Three out of 4 patients with progressive bulbar paralisis and 5 out of 11 cases of amyotrophic lateral sclerosis had abnormal MRI. Such MRI abnormalities have neither been found in patients with progressive muscular atrophy nor in controls, suggesting that they may be the hallmark of pyramidal tract degeneration in motor neuron disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314764
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    A prospective evaluation of OC125 and magnetic resonance imaging in patients with ovarian carcinoma (1990)
    Springer
    European journal of nuclear medicine 16 (1990), S. 311-316 
    Details
    ISSN: 1619-7089
    Keywords: Magnetic resonance imaging ; Immunoscintigraphy ; Ovarian carcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Eighteen patients with suspected primary or recurrent ovarian carcinoma have been investigated in each case by the assay of serum levels of the antigen CA125, immunoscintigraphy using131I-OC125 antibody and magnetic resonance imaging using a 0.15 Tesla-system. The final diagnosis was confirmed by laparotomy or laparoscopy. Serum levels of CA125 ranged between 5 and 780 units/ml (normal range 〈 35). Antibody images and MRI were truly positive in 11 patients, 2 of whom were subsequently found to have bowel tumours. MRI showed greater detail of smaller lesions whilst immunoscintigraphy was more suited to the detection of distant metastases. In 7 patients the antibody images were positive whilst the serum marker levels were normal. This pilot study provides a preliminary comparison of the more recent techniques currently being evaluated for the detection of ovarian carcinoma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00842786
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    Infarct sizing by scintigraphic techniques and nuclear magnetic resonance imaging (1990)
    Springer
    European journal of nuclear medicine 17 (1990), S. 83-90 
    Details
    ISSN: 1619-7089
    Keywords: Myocardial infarct size ; Myocardial scintigraphy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Assessment of myocardial infarct size is the cornerstone in the evaluation of interventions designed to salvage myocardium, such as thrombolytic therapy and urgent coronary angioplasty. Enzymatic methods have probably the highest accuracy but can only be used in the very early phase of infarction. The electrocardiogram allows a reasonable estimate of infarct size, but its confidence limits are wide, and in inferior wall infarction the estimates are unreliable. In recent years, radionuclide techniques have been successfully used to identify, localize and determine infarct size in the course of acute myocardial infarction. These scintigraphic measurements have provided important diagnostic, therapeutic and prognostic information based on the extent of myocardial damage. Nuclear magnetic resonance imaging, particularly with contrast enhancement, is one of the methods that have the greatest potential in accurately delineating myocardial infarct size. Nuclear medicine procedures, on the other hand, employ more biologically oriented tracers and offer promise in view of their ability to monitor biochemical alterations as an effect of therapy in the course of myocardial infarction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00819409
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Non-invasive histochemistry of plant materials by magnetic resonance microscopy (1990)
    Springer
    Protoplasma 159 (1990), S. 70-73 
    Details
    ISSN: 1615-6102
    Keywords: Histochemistry ; Nuclear magnetic resonance ; Non-invasive techniques ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have combined nuclear magnetic resonance (NMR) imaging on the microscopic scale with chemical shift selection to demonstrate the application of magnetic resonance imaging (MRI) to plant histochemistry. As an example of the method we have obtained separate images of the distribution of reserve oil and anethole in dried fennel mericarps. The technique can be employed to separately image the distribution of aromatics, carbohydrates, oils, water and possibly fatty acids in suitable plant materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01326636
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Effect of strength training on the relationship between magnetic resonance relaxation time and muscle fibre composition (1990)
    Springer
    European journal of applied physiology 61 (1990), S. 33-36 
    Details
    ISSN: 1439-6327
    Keywords: Magnetic resonance imaging ; Relaxation time ; Muscle fibre composition ; Strength training
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of muscle hypertrophy on the relationship between magnetic resonance (MR) relaxation time and muscle fibre composition was investigated. Relaxation time and muscle fibre composition were measured in five subjects before and after a 20-week period of strength training. Muscle fibre composition in all subjects exhibited a significant shift to a predominance of fast-twitch (FT) fibres as a result of 20-week strength training (% area FT fibres: mean values from 49.8%, SD 17.9% to 57%, SD 5.6%; P〈0.05). Longitudinal relaxation time (T1) and transverse relaxation time (T2) were prolonged significantly after strength training (T1 mean values from 334.9 ms, SD 13.6 to 359.0 ms, SD 9.0, P〈0.001; T2 from 27.5 ms, SD 0.9 to 30.8 ms, SD 2.3, P〈0.05). A constant relationship was observed in changes caused by strength training in muscle fibre composition (% area FT) and relaxation time, with a high correlation obtained between both parameters. These results indicate that MR relaxation time can be used for non-invasive estimation of muscle fibre composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00236690
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    Intersession replicability of dipole parameters from three components of the auditory evoked magnetic field (1990)
    Springer
    Brain topography 3 (1990), S. 311-319 
    Details
    ISSN: 1573-6792
    Keywords: Magnetoencephalography ; Auditory evoked fields ; Current dipoles ; Magnetic resonance imaging ; Source localization ; Replicability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The replicability of dipole localizations between sessions in an unselected group of subjects was studied. Auditory evoked magnetic fields (AEMFs) in response to contralaterally and ipsilaterally presented 1 kHz tone bursts were recorded from the right hemisphere of 12 subjects with normal hearing in two replicate sessions several days apart. Three long-latency components of the AEMF were studied, occurring at latencies near 50 msec (P1m), near 100 msec (N1m) and near 165 msec (P2m). A spherical model of the head was used to fit equivalent-current dipoles to the data. Statistical analysis of dipole parameters revealed virtually no differences between the two testing sessions. The variability between sessions had a mean absolute difference of 3 to 10 mm for the spatial parameters. Comparison of dipole parameters between components showed that there was a replicable, but nonsignificant, trend for a difference in the location of the N1m from contralateral vs. ipsilateral stimulation, and a statistically significant confirmation that the P2m is located anterior to the N1m for contralateral stimulation. Magnetic resonance images from each subject were used to locate the dipoles near the primary auditory cortex in the Sylvian fissure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01135440
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Polymer blend containing a thermotropic polyester with long flexible spacer in the main chain (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 22-29 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer blends of nylon 66 and thermotropic polyester with long flexible spacers in the main chains were prepared by melt mixing. The samples were made as single filaments by passing the polymer blend through a small and round die of a capillary rheometer. Mechanical properties of blends showed that the modulus and strength of nylon 66 could be improved without reduction of extensibility. The morphology of fractured surfaces was observed by a scanning electron microscope (SEM). It showed that the microfibrillar structure of a thermotropic polyester was formed by extensional flow while the spherical and ellipsoidal particles in the nylon 66 (matrix polymer) were produced by shear flow. The polyester particles were occasionally covered with adhering matrix polymer because of good adhesion between these two polymers. They were highly elongated by tensile stress without loss of elongational characteristics of blends. This fact was explained by very good adhesion between the two phases.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300105
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Gelation in thermosets formed by chain addition polymerization (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 83-89 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The physical behavior of the diglycidyl ether of bisphenol A, cured with different concentrations of 2-ethyl-4-methylimidazole, was examined with dynamic mechanical and dielectric analyses, differential scanning calorimetry, and solvent extraction studies, ‘The network formation process was shown to depend strongly on the imidazole concentration’. At high imidazole concentrations, the gel point was characterized by a decrease in sol fraction, the crossover of the dynamic moduli and a rapid increase in viscosity. At low imidazole concentrations, the viscosity remained low until the sol fraction approached zero. For this system, the gel point, which occurred prior to the dynamic moduli crossover, was characterized by comparing the thermal properties of the network with the viscosity and dielectric behavior of the resin system during cure.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    Calculated stresses in dual coated optical fibers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 108-117 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We examine several practically important problems, related to the mechanical behavior of dual coated optical fibers: low temperature microbending, evaluation of spring constant due to coating layers, strength of the end portions of fibers clamped in terminal fixtures, and prediction of stresses caused by the misalignment of the openings in the frame and in the terminal fixture. The developed formulas are simple, easy-to-use, and clearly indicate the role of the major factors affecting the mechanical behavior of the fibers. The obtained results can be of help in physical design of dual coated fibers and optical interconnections.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    Energy absorption characteristics of polymeric foams used as cushioning materials (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 129-133 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The “Efficiency of Energy Absorption” (or “Efficiency”) and “Ideality” parameters were evaluated for several plastic foams and were found to be very useful in choosing an appropriate cushion for the protection of a specific product. The maxima in these parameters were found to be in the same range of stresses, when derived from dynamic measurements or from predicted stress-strain curves based on previously proposed “Reference” and “Modified Boltzman Superposition” Models. For the rate independent foams the maxima in these parameters do not change with strain rate and can therefore be derived from slow, constant rate (“static”) experiments. For rate dependent foams however, the maxima from “static” measurements were found to be in a lower range of stresses than those derived from dynamic ones. As a result, slow rate compressive measurements do not predict well the behavior of the foams during impact and the use of the “Reference” and “Modified Boltzman Superposition” Models is required for good predictions. It was found that the suffer PS and PE foams attain maximum Efficiency and Ideality at higher stresses than the more flexible PUR foams.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300210
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Transition mechanism from elastic deformation to plastic flow in poly(methyl methacrylate) (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 96-107 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Sudden changes of compressive strain-rate on glassy poly(methyl methacrylate) lead to the conclusion that the post-yield state under a constant stress is a state of steady flow in the polymer. Non-linearity between the stress divided by temperature and the logarithm of strain rate for this steady plastic flow can successfully be analyzed using the Eyring equation with structural factors variable depending on stress and temperature. This analysis gives a unique functional relationship between the activation entropy and the activation enthalpy, which agrees fairly well with that for the melt derived from the WLF equation. This agreement provides a direct evidence verifying structural change of the glass into liquid-like structure and enables us to recognize the conformational arrangement as an essential structural parameter controlling molecular mobility. Another experimental relation between the Eyring factors - the activation volume and the activation enthalpy - permits us to estimate the magnitude of an elementary volume for the molecular movement in the melt as a function of temperature. Moreover, the experimental finding of the steady flow in the glassy polymer motivated us to propose a transition mechanism from elastic deformation to plastic flow in which the internal viscosity or the activation volume is introduced as a single parameter representing the transient state of the structure.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300206
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Experimental modeling of solvent-casting thin polymer films (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 118-123 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An apparatus was designed and assembled to study the solvent removal from solution-cast thin polymer films. The computer interfacing of a thermogravimetric analyzer, spectrophotometer, electronic flowmeters, and control valves for the apparatus enabled the preprogramming of the carrier gas velocity, carrier gas solvent content, and temperature profiles to simulate the environment experienced in large parallel flow industrial driers. The apparatus has also been designed and operated to enable the visual observation of the drying film with an optical microscope. Initial experimental studies conducted with the apparatus involved the effect of temperature on solvent removal. The results indicate that high dryer gas temperatures can apparently cause skinning of the film surface resulting in slower solvent removal rates. The skin formation can be suppressed by higher solvent concentration in the carrier gas. The visual observations revealed the formation of standing waves in the film surface during drying at high gas velocities (〉2OO cm/min). The wave formation at least partially overcomes the effect of skinning by increasing the surface area of the film, and may be the manifestation of flow instabilities involving circulation within the film.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300208
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Ultrasonic processing of thermoplastic foam (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 147-152 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Ultrasonically induced bubble formation for the production of thermoplastic foam was investigated experimentally and theoretically as a basic study. A general purpose polystyrene and blends of low density polyethylene and polyethylene wax were saturated with nitrogen gas under various pressures and the ultrasonic excitation was applied to the polymer system upon release of gas pressure. The ultrasonic nucleation of bubbles in the polymer matrix was modeled by utilizing the classical nucleation theory. The negative pressure generated by the ultrasonic excitation was considered as the environmental pressure at the moment of nucleation. The experimental results showed that the heterogeneous nucleation must be used for ultrasonic foaming of the viscous fluid and the homogeneous nucleation for the low viscosity fluid. The theoretical analysis also indicated that the ultrasonic nucleation can be applied to the production of thermoplastic foam if the ultrasonic excitation generates large enough negative pressure.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300304
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Rheology-morphology relationships in nylon 6/liquid-crystalline polymer blends (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 7-12 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Extrusion measurements have been carried out on blends of nylon 6 and a liquid-crystalline copolyesteramide (LCP). The flow curves at low temperature show a behavior similar to that of pure LCP with a rapid rise of the viscosity at low shear rates. At high shear rates the viscosity is lower than that for each of the two components. This minimum has been attributed to the lack of interactions between the two phases and to the formation of fibrils of the LCP phase. The SEM analysis shows, indeed, that fibrils of the LCP phase are produced in the convergent flow at the inlet of the capillary at high shear rates. These fibrils are lost during the flow in the long capillary.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300103
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    Rheological properties of a liquid crystalline copolyester (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 124-128 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Rheological studies of an experimental liquid crystalline (LC) copolyester were carried out using a capillary rheometer and a cone and plate rheometer. Rheological characteristics of the polymer in the nematic state were observed. The nematic melt was found to be pseudoplastic and the degree of pseudoplasticity varied with shear rate. Melt viscosity was found to decrease with shear rate. Negative die swelling was observed at the exit of the capillary rheometer at temperatures marginally above the solid-nematic transition temperature of the polymer and was also found to be a function of shear rate. The dynamic mechanical properties of the polymer were studied as a function of temperature. The activation energies of flow and of dynamic mechanical deformation were calculated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300209
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Enhancing adhesion by ion beam-induced atomic mixing at the interface between copper film and polyimide substrate (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 137-141 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Ion beam mixing was used to improve the adhesion between deposited Cu film (400 Å) and polyimide (PI) substrate. Ar+ ion with the energy levels between 180 and 200 keV, and the dose between 1014 to 4 × 1016 ions/cm2 were used. The surface analyses were carried out by Rutherford Backscattering Spectroscopy (SEM). RBS analysis, using 2 MeV He+ ions, showed mixing of Cu and FI and the mixing depended on the Ar+ energy and dose. The X-ray study showed a very broad halo for deposited Cu film but the (111) peak appeared after the Ar+ implantation and the peak increased with Ar+ ion dose. Optical micrographs showed that Cu film formed circular bubbles after many thermal cycles when adhesion was poor and fracture cracks when adhesion was good.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300302
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    Measures of mixing in laminar flow (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 153-161 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The general domain in which this work resides is that of mixing in creeping flows. Mixing, in this context, refers to the stretch of an interfacial line, or area in a strain field. The advancement of mixing technology is applied to the design of continuous mixers used in polymer processing. The geometric designs included single screw extruders, static motionless mixers, and co- and counter-rotating twin screw extruders. The co-rotating twin screw extruder was chosen to be studied in detail since it enjoys wide applications and, for which, little understanding of the contribution to mixing in the different screw geometries is known. In order to evaluate the rate of mixing for the non-uniform strain history flows, the method for measuring mixing had to be reexamined and broadened. An automated method has been developed which incorporates a digital camera and a computer to analyze the cross-sections of interest. Two measures of mixing - the correlation function and the distribution function - are developed to describe mixing in these regimes. These measures are applied successfully to the mixer geometries revealing subtle differences as to the nature of mixing in each.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300305
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Rotary injection reaction injection molding (RI-RIM). Part II: Interfacial segregation of release systems (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 175-186 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper describes the shear imposed interfacial segregation of release systems for the facilitated attenuation of polyurethane (PU) adhesion to metal coun-terfaces using a RI-RIM system. It is shown that the migration rate of the dispersed release additives due to a shear imposed stress in the resin fluid is much greater than that arising from Fickian diffusion, thereby removing a vital constraint from conventional practice. The novel rotary injection RIM system is presented to simulate the on-line injection and shear induced interfacial segregation in model PU/abherent systems. A wide range of recipes comprising single (liquids or solids) and multicomponent (liquid-liquid and solid-liquid) release materials were injected into the polymerizing resin mixture to provide cohesively weak and friable “particle” boundary layer assemblies at the PU/metal interface. An instrumented Blister Test was employed to evaluate the quality of the molded interfaces in terms of adhesion and the concentration distribution of the injected species in the final cured moldings was determined through high pressure liquid chromatography (HPLC). A comparison of the results on the shear modified and the compounded interfaces confirm an accentuated lateral migration of the additives to the interface resulting in an appreciable diminution in the adhesion of the system. Finally, transport models are suggested to account for the observed augmented transport.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300307
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300401
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Mechanical properties and behavior of open cell foams used as cushioning materialsFirst part appeared in Polymer Engineering & science, Jan. 1990, 30, 129. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 197-201 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is the purpose of the present publication to show that most of the phenomenological viscoelastic theories developed for bulk polymers can be readily adapted to plastic foams in order to evaluate their mechanical properties. In addition it will be demonstrated how the mechanical properties of open cell plastic foams can be predicted from a few simple compression and relaxation experiments.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300402
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    The plane-strain essential work of fracture as a measure of the fracture toughness of ductile polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 211-218 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We have extended the essential work of fracture technique to allow for the determination of the plane-strain essential work of fracture. The new technique is to measure the specific work of fracture as a function of ligament length in deeply double edge notched samples. This type of data is then experimentally corrected to remove the plastic work of fracture and leave only the essential work of fracture as a function of ligament length. By extrapolating the essential work of fracture to zero-ligament length, we claim to be measuring the plane-strain essential work of fracture. This new technique was applied to two rubber toughened nylons and to a series of polyethylenes. The plane-strain essential work of fracture was found to be independent of thickness. Where comparison can be made to J-integral testing, the plane-strain essential work of fracture was similar to the critical J-integral, JIc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300404
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Liquid crystal polymer-carbon fiber composites. Molecular orientation (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 228-234 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The objective of this work has been to study composite systems in which carbon fibers are dispersed in a liquid crystal polymer matrix. The fundamental point of interest here has been the interfacial response that fiber surfaces can potentially induce in self-ordering polymers. The matrix material used was a thermotropic liquid crystal polyester synthesized in our laboratory from the monomers p-acetoxybenzoic acid, diacetoxyhydroquinone, and pimelic acid. The aromatic-aliphatic polymer was characterized by NMR as a chemically disordered polymer of the three structural units which exhibits a nematic phase at temperatures above 150°C. Breadline proton NMR above the solid to liquid crystal transition was used to measure the rate of magnetic alignment of molecules in the matrix and polarized optical microscopy was used to analyze interfacial zones in composite samples. Fiber surfaces were found to influence the orientation and orientational dynamics of a liquid crystal polymer matrix. This was revealed by enhanced rates of magnetic orientation in the polymer melt when carbon fibers are dispersed in the medium. Fiber surfaces were also found to stabilize nematic ordering of the polymer as the melt was heated towards complete isotropization. The phenomena discovered here may originate in the development of zones around fibers with a common molecular orientation anchored by the carbon surface.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    Impact fracture toughness tests on polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 241-248 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of impact tests are described in which the plane strain fracture toughness, Kc1, of five different polymers is measured using a three point bend specimen at striker speeds up to 5m/s. At low speeds Kc1 is determined using the maximum load and a static analysis, but at speeds greater than 1 m/s the dynamic effects render the load signal unusable. For the higher speeds the fracture is timed using contact and crack propagation gages and the analysis is performed using the striker displacement at fracture. A dynamic analysis is used to convert this measurement to the true specimen displacement and Kc1 is determined from this. The apparent downward trends in the Kc1 results obtained, especially at speeds above 3m/s, are discussed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300408
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300501
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    Temperature measurements of polymer melts in the heating barrel during injection molding. Part 3: Effects of screw geometry (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 385-393 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We have developed a new method to measure the true temperature of the polymer melt and its three-dimensional distribution of a shot stored in the reservoir during injection. By means of this method, it is demonstrated that the temperature distribution of the polymer melt stored in the reservoir is strongly dependent on the setup molding conditions, the polymer investigated, and the geometry of the screw used. Further, it is noted qualitatively that there are two major effects of screw geometry on the temperature distribution of polymer melts. One, which governs strongly the temperature in the high temperature zone, is shear heat generated within the polymer itself in the metering zone of the screw during the transporting process. The second is the ability to preheat and plasticate the polymer in the compression zone, which is indispensable for uniform plastication.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300702
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    The breaking strength of perfect polymer fibersThis paper was presented at the American Chemical Society Meeting in Dallas Texas, April 1989, in the Polymer Science Award Symposium Honoring W. R. Krigbaum. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 437-443 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The breaking strength, strain at break, and work to rupture of perfect fibers prepared with polymers of finite molecular weight are calculated by treating the perfect fiber as a stressed crystal undergoing a crystal-melt phase transition. In this view, a tensile load destabilizes the crystal and depresses its melting point. When the load is sufficient to lower the melting temperature to the ambient condition the fiber melts - i.e., fails. The theoretical equations (extremely simple) are applied to several common polymer fibers. The maximum tensile strength of polyethylene, for example, is calculated to be 7 to 9 GPa, in good agreement with current experimental results.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300802
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Relationship between electron sensitivity and chemical structures of polymers as electron beam resist. VII: Electron sensitivity of vinyl polymers containing pendant 1,3-dioxolan groups (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 449-452 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Vinyl polymers containing pendant acetal groups were synthesized using (2,2-dimethyl-l,3-dioxolan-4-yl)methyl acrylate (DMA) and (2,2-dimethyl-l,3-dioxo-lan-4-yl)methyl methacrylate (DMM), and were evaluated as negative electron beam (EB) resists. It was found that the EB sensitivity of polymers containing acetal groups in the side chain was higher than that of polymers containing acetal groups in the main chain. A high sensitivity of 3.6 × 10-8 C/cm2 was observed. Copolymers of DMA or DMM with styrene were also synthesized in order to improve the durability for dry etching process. It was found that the copolymers had an excellent dry etching durability and were adaptable to EB lithography.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300804
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Thermal behavior of transparent poly(etheretherketone)(PEEK) film (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 453-458 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The thermal behavior of poly(etheretherketone)(PEEK) film heated in an open differential scanning calorimetry (DSC) pan at 20°C/min is distorted by relaxation of the strained film. PEEK film in a closed pan or quenched PEEK in open or closed pans shows a glass-transition temperature (Tg) around 144°C, cold crystallization (∼22 J/g) at 177°C, melt-temperature (Tm) peaking at 335-340°C, with an enthalpy of fusion of 32-34 J/g, and recrystallization on cooling at 285°C, with a crystallization exotherm of about 40 J/g. The enthalpy of fusion decreases with increasing heating rate from 2-100°C/min and approaches the enthalpy of cold crystallization. With increasing heating rate, further crystallization of PEEK during the DSC scan is suppressed. With increasing cooling rate, PEEK melt crystallizes at larger supercoolings to a lesser extent. Crystallization on cooling the melt was more complete than cold crystallization and annealing on heating.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300805
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Electrical and dielectric properties of segregated carbon black-polyethylene systems (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 459-468 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The electrical and dielectric properties of compression-molded segregated polyethylene-carbon black mixtures are described in the frequency range between 10 and 8000 kHz as a function of frequency, temperature, and carbon black loading. The segregated systems investigated exhibit insulator-conductor transitions in the range 0.25-0.65% (volume/volume) carbon black. The dielectric constant and the dissipation factor of the conductive samples are relatively very high in the frequency range studied. The dielectric constant increased sharply with the carbon black concentration, and then increased moderately beyond the insulator-conductor transition. The dissipation factor-concentration curves for different carbon blacks show maximum values in the vicinity of the critical concentration values. The dielectric properties of these systems are discussed in terms of interfacial Maxwell-Wagner polarization effects.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300806
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    Heat capacity of polypropylene composite at high pressure and temperature (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 476-479 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The heat capacities of isotactic polypropylene and its composite with glass fiber have been measured at high pressure, up to 7 MPa, in the melt state by high pressure differential scanning calorimetry (HPDSC). The values also have been calculated from the data of specific volume (V) measured by dilatometry and thermal conductivity (κ) and thermal diffusivity (α) measured by a compensating hot wire method. The values of the heat capacity measured from HPDSC are consistent with those from the calculation method. The heat capacities of molten polypropylene and its composite increase linearly with temperature at a constant pressure and decrease with pressure at a constant temperature. It was found that the heat capacity of polypropylene is insensitive to molecular weight. The heat capacities of molten polypropylene composites are found to be predicted by an additive rule from the weight fractions of heat capacities of polypropylene and glass fiber.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300808
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Measurement and correlation of mutual diffusion coefficients for styrene-butadiene rubber (SBR)-ethylbenzene systems (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 480-484 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The mutual diffusion coefficients for styrene-butadiene rubber (SBR)-ethylbenzene systems were measured using a sorption apparatus with a quartz spring at 100 and 130°C for mass fractions of ethylbenzene ranging from 0 to 0.17. The mutual diffusion coefficients were correlated with good agreement by the free-volume theory.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300809
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300901
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Studies on the effect of electrode type and substrate temperature on plasma polymerization of two model compounds: Acrylonitrile and hexamethyldisiloxane (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 485-489 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymers were prepared from saturated (HMDS) and unsaturated (AN) monomers in a radio frequency discharge (plasma). The effect of selected parameters such as electrode type (such as Cu, Zn, Ni, Al), reactor type, and substrate temperature (other parameters constant) on chemical structure and the rate of polymer deposition was examined by Fourier transform infrared (FTIR) spectroscopy. Differences in the nature of electrodes and reactor types were found to yield similar plasma products with similar rates of deposition for two monomers. In the tubular reactor used, deposition rates were observed to decrease with increasing substrate temperatures showing different dependencies on temperature for the monomers tested.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300810
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Dielectric and magnetic properties of random and segregated ferrite polystyrene composites (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 469-475 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dielectric and magnetic properties of polystyrene composites containing barium or nickel-zinc ferrites were studied as function of the ferrite concentration and field frequency. The composites were prepared by methods yielding a random distribution of the ferrite particles or segregated structures. Barium ferrite-poly-styrene composites exhibited a typical insulator behavior, and only above 60% ferrite were high values of the dielectric properties noted at the lower frequencies, decreasing gradually with frequency to the low values typical of the higher frequencies. The mode of barium ferrite particle distribution did not affect the dielectric properties. The nickel-zinc ferrite systems demonstrated a conductor type behavior. An apparent insulator-conductor transition was observed, having lower values for segregated than for random distributions. The magnetic permability of barium ferrite-polystyrene composites above 10% ferrite increases with the ferrite concentration, whereas the magnetic dissipation factor steeply increases with concentration above 40% ferrite.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300807
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    Morphology and properties control on rubber-epoxy alloy systems (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 493-510 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Morphology and properties of polymer alloys can be controlled by thermody-namlcally reversible (structure freeze-in) or irreversible (structure lock-in) processes by simultaneously manipulating miscibility, mechanisms of phase separation, glass transition temperature (structural relaxation), and cure kinetics of polymer systems. Using phase diagrams consisting of binodal and spinodal curves, the morphology of epoxy/CTBN (carboxyl-terminated butadiene acryloni-trile copolymer) systems can be controlled by the mechanism of nucleation and growth or by spinodal decomposition via simultaneously manipulating the kinetic processes of phase separation and curing reactions. We have found that the particle size of the rubber reinforcement in epoxies is affected by the mechanisms of phase separation. Phase separation by nucleation and growth gives larger rubber particles than the corresponding phase separation by spinodal decomposition. This contrast in the morphology development is the consequence of controlling phase separation through chemorheological behavior. Medication of the phase separation kinetics in epoxy/CTBN systems was extremely effective at altering both morphology and properties of these alloys. This technique offers a means to shift the glass transition temperature of the rubber-rich phase drastically without reducing the glass transition temperature of the epoxy-rich phase significantly. Such control over morphology is the key to ultimately controlling material properties. This morphology manipulation allows us to tailor the mechanical properties of alloy systems.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300902
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Morphology of plastic/rubber blends (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 511-518 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of polypropylene (PP) and ethylene-propylene rubber (EPR) and blends of polystyrene (PS) and styrene-butadiene rubber (SBR) were prepared in a laboratory-scale internal mixer at various blend compositions and rotor rates. Blend morphology was studied by means of electron microscopy. For each blend pair under the given processing conditions, the phase inversion process occurred progressively with respect to the variation in blend composition; it is within this composition range of phase inversion that dual-phase continuity was observed. In addition, Characteristic torque values of blends were found to deviate negatively from a linear additivity rule; the composition range of maximum deviation from linear additivity corresponded approximately to the composition range where dual-phase continuity was observed. Sperling's predictive scheme was found to yield acceptable (although not completely satisfactory) estimates for compositions of dual-phase continuity in the present systems. It was also observed that partial cross-linking of SBR during the mechanical blending process, as suggested by the appearance of a cure peak in the torque curve and supported by infrared spectroscopic evidence, resulted in morphological features drastically different from those of the uncured blends.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300903
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Characterization and processing of blends of polyethylene terephthalate with several liquid crystalline polymers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 519-526 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of an engineering thermoplastic, poly(ethylene terephthalate) (PET), and two liquid crystalline polymers (LCPs) viz., copolyesters of PET and parahydrox-ybenzoic acid (PHB) in 40/60 mole percent (LCP60) and in 20/80 mole percent (LCP80) were prepared. A blend of LCP60 and LCP80 in 50/50 weight percent (LCP60-80) was blended with PET. Both flat films and rods were extruded and their properties examined. The morphology of the films investigated using Scanning Electron Microscopy (SEM) revealed that the LCP phase remained as dispersed droplets in the PET matrix. In spite of the lack of fibrillation in these films, the mechanical properties were enhanced to some extent with a maximum at 10 weight percent of the LCP phase. However, in the case of the rods thin fibrils of the LCP phase of the order of 1 μm in diameter were observed provided the composition of the LCP was 20 weight percent or greater. This success In achieving fibrillation is through to be due to the extensional flow fields present at the entrance of the capillary die and the fact that a short L/D ratio die was used. Differential Scanning Calorimetry (DSC) thermograms of the extruded films indicated that the LCP phase may act as a nucleating agent for the crystallization of PET. Rheology of the blends revealed that the complex viscosity of the blends is not much different from that of pure PET. This is attributed to the partial miscibility of the two components. Based on the DSC results and residence times in the extruder, it is concluded that no significant transesterification reactions appear to have: taken place in the blends. The rheology is studied further with respect to the cooling behavior of the pure components and factors important to the fibrillation of the LCP phase and the formation of in-situ reinforced composites are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300904
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Corrections (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 618-618 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301009
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    Thermomechanical properties of 1C molding compoundsPresented at the Annual Meeting of American Institute of Chemical Engineers in San Francisco, California on November 6, 1989. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 609-617 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Eight commercial semiconductor grade epoxy compounds that are used to encapsulate 1C (integrated circuit) devices have been evaluated for their ability to minimize the development of thermal stresses which can cause failure during device temperature cycling. Thermal expansion, dynamic modulus and adhesion studies are used to describe the mechanical interaction between the plastic package and the silicon device it surrounds. A “figure of merit” is defined for the development of stress on the 1C device as it is cooled after the packaging process. The stress is shown to be proportional to the product of three terms: (αp-αs) Ep (Tanch-T) where αp and αs are the expansion coefficients for the plastic and silicon, respectively, Ep is the modulus of the epoxy and Tanch is the temperature at which the epoxy becomes anchored to the silicon device during transfer molding. In addition, the importance of good adhesion between the epoxy encapsulant and the silicon device to prevent package cracking has been demonstrated by finite element analysis and a novel adhesion test.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301008
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Grafting of a liquid crystal polymer on carbon fibers (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 603-608 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Covalent grafting of mesogenic chains on carbon fiber surfaces was attempted as part of a study on composite materials containing liquid crystal polymer matrices. Grafting in these composite systems is viewed not only as a mechanism to achieve interfacial bonding but also as an approach to modify the interphase physical structure. The synthetic approach to grafting involved the in-situ polymerization of monomers in the presence of functionalized fibers in order to grow chains covalently attached to the fibers. The chemical mechanism may be viewed as the “transesterification of car boxy lated fibers” with acetylated monomers. The monomers used were pimelic acid, p-acetoxybenzoic acid and diacetoxy hydroquinone which are known to yield upon condensation a chemically aperiodic nematic polymer. Evidence for grafting was obtained from X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis on fibers retrieved from composite samples. Interestingly, SEM micrographs of fractured composite specimens containing the mesogen-grafted fibers reveal excellent wetting and interfacial bonding of a liquid crystalline matrix on the carbon surfaces. Based on theoretical considerations for end-adsorbed macromolecules and the nematogenic nature of the grafted chains we infer that dense layers of adsorbed polymer may form at the interfaces studied. From a materials point of view the in situ growth of liquid crystal polymer chains on fibers may offer mechanisms to control composite properties through both bonding and molecular orientation in interfacial regions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301007
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Chain structure, phase morphology, and toughness relationships in polymers and blendsPresented at the Asilomar Conference on Polymeric Materials, Monterey, California, January 30-February 2, 1990, and 32nd Microsymposium on Macromolecules “Polymer Blends,” Prague, Czechoslovakia, July 17-20, 1989. (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 753-761 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We present chain structure, phase morphology, and toughness relationships in thermoplastic polymers and polymer/rubber blends. In neat polymers, molecular aspects of craze/yield behavior are controlled by two chain parameters: entanglement density νe and characteristic ratio C∞. The crazing stress is proportional to νe1/2, and the yield stress is proportional to C∞. The dispersed rubber toughens a polymer/rubber blend mainly by promoting energy dissipation of the matrix. The toughening efficiency correlates with the rubber phase morphology and the chain structure of the matrix.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301302
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    Isothermal volume relaxation in aged polycarbonate measured by positron annihilation lifetime spectroscopy (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 762-768 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The positron annihilation lifetime spectroscopy (PALS) technique is used to measure volume relaxation in physically aged glassy polycarbonate. The relaxation times and activation energy calculated for the isothermal relaxations in the aged polycarbonate are greater than those parameters calculated for unaged polycarbonate. The activation energy of 8.2 kcal/mol in the aged polycarbonate is used to identify the phenyl group motion or the cooperative carbonate-phenyl interaction as the molecular features responsible for the thermally induced open volume relaxations. It is postulated that the open volume relaxation kinetics as measured by PALS can be used as a nondestructive indication of property differences between aged and unaged polycarbonate.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301303
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    Crystallization of isotactic (D,L) poly(propylene oxide) in the presence of fine-particle silica. I: Radial growth rates of spherulites (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 769-775 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of added silica on the spherulite radial growth rates of isotactic poly(propylene oxide) (i-PPrO) has been investigated by optical photomicroscopy. Two different i-PPrO samples were used of different molecular weights and isotacticity, 87 and 100% as determined by 13C NMR. The addition of fine particle silica, an effective nucleating agent, depresses the spherulite growth rates throughout the entire temperature range, but the effect is more dramatic for the i-PPrO of lower isotacticity. For a given sample, the retardation increases as the quantity of filler increases. The growth rate-temperature behavior is analyzed in terms of the classical Hoffman-Lauritzen equation, modified to take into account the polymer-filler interaction.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301304
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Structural heterogeneity in epoxies (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 835-840 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects of different cure procedures on the structure and properties of epoxy samples made from diglycidyl ether of bisphenol A (DGEBA) and mixtures of two linear aliphatic diamines were studied. The elastic modulus, fracture toughness, impact resistance, and glass transition temperature were determined for various cure schemes. The morphologies of the cured resins were characterized with small angle X-ray scattering. The results show that samples with the same average morphology (molecular network structure) have similar elastic moduli and glass transition temperatures. If some heterogeneity is introduced in the molecular network structure without changing the average structure, however, the experiments indicate that the toughness can be increased without significantly sacrificing other properties.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301406
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    Effect of dispersion of particles on viscoelasticity of CaCo3-filled polypropylene melts (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 841-847 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Viscoelastic properties of polypropylene melts filled with small (0.15 μm) and large (4.0 μm) CaCO3 particles have been measured. The effects of particle size, loading, and rheological history on the dispersion of particles have been investigated. The dispersion of particles was found to decisively influence the viscoelastic properties of these filled polymers. The systems filled with large particles exhibit a relatively stable viscoelastic behavior. The small particle-filled polymers with low loading are stable similarly to the large particle-filled system. For the system filled with 30 wt% small particles, there appears a “second plateau” in the storage modulus G′ curve in low frequency region and the height of the second plateau depends strongly on the rheological history. The results are interpreted in terms of the formation of an internal structure of particles. It was found that the internal structure of particles is broken up by a steady shear flow and the dispersion of particles is changed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760301407
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...