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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3534-3540 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated the effects of surface roughness and grain boundary diffusion (GBD) at elevated temperatures on the Auger-electron-spectroscopy sputter depth profiles of Co–Ag bilayers and the GBD process of Ag atoms in Co. The Ag layer in the Ag/Co bilayer is transformed from a uniform layer to discrete islands by heat treatment. Enhanced mobility during sputtering at elevated temperatures makes Ag atoms migrate continually from islands to cover neighboring exposed Co, which reduces the size of Ag islands. On the other hand, the surface morphological modification of Co/Ag bilayer does not occur by heat treatment, and the depth profile at 340 °C resembles that from a uniformly intermixed film, which shows a drastic difference from that of Ag/Co. This is explained with a very thin and stable accumulation of Ag on the Co layer by GBD. A model of structural changes in Co/Ag subjected to ion sputtering at elevated temperatures is proposed on the basis of the results. The activation energy and pre-exponential factor for GBD of Ag in Co are found to be 0.46±0.06 eV and ∼1×10−8 cm2/s, respectively. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 135-138 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Cu (400 Å)/polyimide was mixed with 80 keV Ar+ and N2+ from 1.0×1015 to 2.0×1016 ions/cm2. The same processes were repeated for the Cu (400 Å)/Al (50 Å)/polyimide system which has Al as a buffer layer. The quantitative adhesion strength was measured by a standard scratch test. X-ray photoelectron spectroscopy was employed to investigate the change in the chemical bonds of the ion beam mixed polyimide substrate and the intermediate effects for the adhesion enhancement in Cu/Al/polyimide. Two distinct tendencies are observed in the adhesion strength: Cu/Al/polyimide is more adhesive than Cu/polyimide after ion beam mixing, and N2+ ions are more effective in the adhesion enhancement than Ar+. The formation of an interlayer compound of CuAl2O4 accounts for the former, while the latter is understood by the fact that N2+ ions produce more pyridinelike moiety, amide group and tertiary amine moiety which are known as adhesion promoters. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-4909
    Keywords: Key wordsAquifex pyrophilus ; Molecular cloning ; Glutamate racemase ; Overexpression ; Thermostability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A gene encoding glutamate racemase has been cloned from Aquifex pyrophilus, a hyperthermophilic bacterium, and expressed in Escherichia coli. The A. pyrophilus glutamate racemase is composed of 254 amino acids and shows high homology with glutamate racemase from Escherichia coli, Bacillus subtilis, or Lactobacillus brevis. This racemase converts l- or d-glutamate to d- or l-glutamate, respectively, but not other amino acids such as alanine, aspartate, and glutamine. The cloned gene was expressed and the protein was purified to homogeneity. The A. pyrophilus racemase is present as a dimer but it oligomerizes as the concentration of salt is increased. The K m and kcat values of the overexpressed A. pyrophilus glutamate racemase for the racemization of l-glutamate to the d-form and the conversion of d-glutamate to the l-form were measured as 1.8 ± 0.4 mM and 0.79 ± 0.06 s−1 or 0.50 ± 0.07 mM and 0.25 ± 0.01 s−1, respectively. Complete inactivation of the racemase activity by treatment with cysteine-modifying reagents suggests that cysteine residues may be important for activity. The protein shows strong thermostability in the presence of phosphate ion, and it retains more than 50% of its activity after incubation at 85°C for 90 min.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 258-263 (Dec. 1997), p. 1455-1460 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 139 (1997), S. 44-51 
    ISSN: 0942-0940
    Keywords: Basilar artery ; dissecting aneurysm ; surgical management ; subarachnoid hemorrhage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Dissecting aneurysm of the basilar artery is a rare but increasingly recognized entity, with a frequently fatal or morbid outcome. Unlike the well established proximal occlusion and trapping approaches to vertebral artery dissections, surgical intervention for basilar lesions has been limited to wrapping techniques for arterial wall reinforcement. We report a case of midbasilar dissecting aneurysm successfully treated by clipping the proximal basilar artery below the level of the anterior inferior cerebellar arteries, allowing retrograde flow via the posterior communicating arteries to provide continued basilar perfusion. With the growing recognition of basilar dissection and pseudoaneurysm formation there is a need for improved therapeutic options. We suggest that definitive treatment can be achieved using the principle of proximal occlusion and flow reversal, and review the pertinent literature on basilar artery dissection.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0942-0940
    Keywords: Aneurysm ; subarachnoid hemorrhage ; coma ; outcome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We report management and outcome data on 118 patients that presented to our emergency room over a 4 year interval (1990–1994) in poor neurological condition after subarachnoid hemorrhage. All patients were treated following a strict protocol. After initial evaluation, patients underwent a head computerized tomography (CT) scan to try to understand the mechanism of coma. If CT did not show destruction of vital brain areas, a ventriculostomy was inserted and ICP measured. If ICP was less than 20 mm Hg, or if standard treatment of increased ICP was able to lower the ICP to a value less than 20 mmHg, patients were evaluated with cerebral angiogram to determine the location of the raptured aneurysm. The lesion was then treated by craniotomy for aneurysm clipping or endovascular obliteration. Postoperative monitoring for vasospasm with clinical exam and transcranial doppler studies was performed routinely. If vasospasm developed, this was managed aggressively with hypertensive, hypervolemic and hemodilutional therapy and, at times, endovascular treatment with angioplasty or papaverine. Outcome was measured at 1 year or more after treatment. Among patients who met criteria for aneurysm treatment, 47% had excellent or good neurologic outcome. There was a 30% mortality rate in these patients. In patients with high ICP, poor brainstem function or destruction of vital brain areas on CT, comfort measures only were offered and almost all died. It is concluded that an approach of early aneurysm obliteration and aggressive medical and endovascular management of vasospasm is warranted in patients in poor neurological conditions after subarachnoid hemorrhage.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé. 150 patients coréens operes pour un remplacement total de hanche non-cimentée ont été triés au hasard en 3 groupes de traitement de prophylaxie de la thrombose. Le groupe A(50): groupe de contrôle. Le groupe B a reçu 1.2 g d’aspirine par jour en 3 doses à compter de 2 jours avant l’opération jusqu’à 14 jours après celle-ci. Le groupe C(50) a reçu des petites molécules de dextrane 500 ml par injection intraveineuse de 50 ml/heure pendant l’intervention et durant les 2 jours suivants. Une phlébographie de contrôle a été rèalisé avant l’intervention et 7 – 10 jours après celle-ci. Le taux de thrombose veineuse profonde (TVP) était de 20% dans le groupe du contrôle, 12% dans le groupe «aspirine» (p 〈0.1 contre contrôle) et 6% dans le groupe de «dextrane» (p 〈0.05 contre contrôle). Parmi les patients développant une TVP, le ratio proximal/distal était cliniquement augmenté dans le groupe du contrôle comparé avec les groupes traités (4 : 1 dans le groupe du contrôle contre 1.5 : 1 dans les groupes traités). L’aspirine et la dextrane ont bien été tolerées. L’obésité (p 〈0.05) et l’administration à long-terme de stéroïde étaient des facteurs de risque pour la TVP avec une signification statistique dans le groupe du contrôle. Les phlébographies per-operatoires faites chez 10 patients ont montré que la flexion (moyenne 40.4°) plus l’adduction (moyenne 11.5°) plus la rotation interne (moyenne 81.5°) se sont traduites par une grave torsion de la veine fémorale accompagné d’une stagnation circulatoire. Les petites molécules de dextrane réduisent significativement le taux de trombose veineuse chez les patients coréens qui ont subi une intervention chirurgicale de remplacement de la hanche et l’aspirine, quoique moins efficace, réduit aussi le taux de TVP. Pour limiter la stagnation de la circulation du sang dans la veine fémorale pendant l’intervention chirurgicale, la rotation interne de la hanche doit être minimisée.
    Notes: Summary. 150 Korean patients undergoing primary uncemented total hip replacement were randomized into 3 treatment groups for deep vein thrombosis (DVT) prophylaxis. Group A(50) were controls; Group B(50) received aspirin 1.2 g daily in 3 divided doses from 2 days before, to 14 days after surgery; Group C(50), received low molecular weight dextran 500 ml, infused intravenously at 50 ml/hour during surgery, and on each of the following 2 days. Contrast venograms were performed prior to surgery and 7 – 10 days after. The incidence of DVT was 20% in the control group, 12% in the aspirin group (p 〈0.1 vs control), and 6% in the dextran group (p 〈0.05 vs control). In patients developing DVT, the ratio of proximal to distal thrombi was increased in the control group as compared to treated groups (4 : 1 in the control group vs 1.5 : 1 in the treated groups). Both aspirin and dextran were well tolerated. Obesity (p 〈0.05) and long-term administration of steroids (p 〈0.05) were risk factors for deep vein thrombosis which reached statistical significance in the control group. Intraoperative venograms performed on 10 patients, showed that hip flexion (mean 40.4°) plus adduction (mean 11.5°) plus internal rotation (mean 81.5°), resulted in severe twisting or kinking of the femoral vein with stagnation of blood flow. Low molecular weight dextran significantly reduce the incidence of deep venous thrombosis and aspirin, though less effective, had a similar effect. Internal rotation of the hip joint should be minimized during operation in order to limit stagnation of blood flow in the femoral vein.
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  • 9
    ISSN: 1617-4623
    Keywords: Key wordsSchizosaccharomyces pombe ; SNF2/SWI2 protein family ; ATPase/helicase domains ; DNA-binding domain ; Chromodomain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The SNF2/SWI2 ATPase/helicase family comprises proteins from a variety of species, which serve a number of functions, such as transcriptional regulation, maintenance of chromosome stability during mitosis, and various types of DNA repair. Several proteins with unknown functions are also included in this family. The number of genes that belong to this family is rapidly expanding, which makes it easier to analyze the common biological functions of the family members. This study was designed to clone the SNF2/SWI2 helicase-related genes from the fission yeast Schizosaccharomyces pombe in the hope that this would help to elucidate the common functions of the proteins in this family. The hrp1 + (helicase-related gene from S. p ombe) gene was initially cloned by PCR amplification using degenerate primers based on conserved SNF2 motifs within the ERCC6 gene, which encodes a protein involved in DNA excision repair. The hrp1 + ORF codes for an 1373-amino acid polypeptide with a molecular mass of 159 kDa. Like other SNF2/SWI2 family proteins, the deduced amino acid sequence of Hrp1 contains DNA-dependent ATPase/7 helicase domains, as well as a chromodomain and a DNA-binding domain. This configuration is similar to that of mCHD1 (mouse chromo-ATPase/helicase-DNA-binding protein 1), suggesting that Hrp1 is a S. pombe homolog of mCHD1, which is thought to function in altering the chromatin structure to facilitate gene expression. Northern blot analysis showed that the hrp1 + gene produces a 4.6-kb transcript, which reaches its maximal level just before the cells enter the exponential growth phase, and then decreases gradually. DNA-damaging agents, such as MMS, MNNG and UV, decrease the rate of transcription of hrp1 +. Deletion of the hrp1 + gene resulted in accelerated cell growth. On the other hand, overexpression of Hrp1 caused a reduction in growth rate. These results indicate that hrp1 + may act as a negative regulator of cellular growth.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1617-4623
    Keywords: Schizosaccharomyces pombe ; DNA-damage inducibility ; Damage-responsive element ; Upstream activating sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheSchizosaccharomyces pombe rhp51 + gene encodes a recombinational repair protein that shares significant sequence identities with the bacterial RecA and theSaccharomyces cerevisiae RAD51 protein. Levels ofrhp51 + mRNA increase following several types of DNA damage or inhibition of DNA synthesis. Anrhp51::ura4 fusion gene was used to identify the cis-acting promoter elements involved in regulatingrhp51 + expression in response to DNA damage. Two elements, designated DRE1 and DRE2 (fordamage-responsiveelement), match a decamer consensus URS (upstream repressing sequence) found in the promoters of many other DNA repair and metabolism genes fromS. cerevisiae. However, our results show that DRE1 and DRE2 each function as a UAS (upstream activating sequence) rather than a URS and are also required for DNA-damage inducibility of the gene. A 20-bp fragment located downstream of both DRE1 and DRE2 is responsible for URS function. The DRE1 and DRE2 elements cross-competed for binding to two proteins of 45 and 59 kDa. DNase I footprint analysis suggests that DRE1 and DRE2 bind to the same DNA-binding proteins. These results suggest that the DRE-binding proteins may play an important role in the DNA-damage inducibility ofrhp51 + expression.
    Type of Medium: Electronic Resource
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