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  • 1
    ISSN: 1432-0509
    Keywords: Key words: Histiocytoma—Liver neoplasms—Liver neoplasms, CT—Liver neoplasms, diagnosis—Liver neoplasms, MR.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: The purpose of the present study was to describe the various imaging features of primary malignant fibrous histiocytoma (MFH) of the liver, a rare tumor of mesenchymal origin. Methods: Sonography (n= 5), computed tomography (CT; n= 5), magnetic resonance (MR) imaging (n= 2), and hepatic arteriography (n= 3) in five patients who underwent partial hepatectomy for tumor resection were retrospectively reviewed and correlated with pathologic findings. Results: All tumors were clearly demarcated from surrounding hepatic parenchyma in sectional imaging with (n= 2) or without (n= 3) a fibrous capsule, which was pathologically verified. Internal architecture of abundant fibrosis, myxoid degeneration, and/or hemorrhagic necrosis reflected the sonographic, CT and MR imaging findings. Marginal tumor staining without definite tumor vasculature was the main feature of hepatic arteriography. There was no intratumoral calcification. All three tumors involving the right lobe of the liver invaded the right hemidiaphragm. Conclusion: Although there were no unique findings of primary hepatic MFH, a combined interpretation of various imaging modalities may elucidate the malignant nature of the tumor.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Abdominal imaging 23 (1998), S. 185-187 
    ISSN: 1432-0509
    Keywords: Key words: Pancreas, cyst—Pancreas—Computed tomography—Ultrasonography.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Two cases of rare lymphoepithelial cyst (LEC) of the pancreas are presented. Although the histogenesis of this lesion is not known, it can be histologically differentiated from other pancreatic and retropancreatic cysts. The importance of its recognition is in the distinction from cystic neoplasm of the pancreas.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0509
    Keywords: Key words: Stomach, MR—Stomach, neoplasm—Stomach, staging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: To evaluate the usefulness of dynamic and delayed magnetic resonance (MR) imaging in the T-staging of stomach cancer and to compare the enhancement pattern of the cancerous lesion and the normal wall. Methods: We performed MR imaging in 46 patients with stomach cancer (including four early gastric cancers and 42 advanced gastric cancers). Axial, sagittal, or coronal two-dimensional fast low-angle shot) MR images for the water-distended stomach were obtained with dynamic protocol, including precontrast images and images obtained 30, 60, 90, and 240–300 s after intravenous injection of the 0.1 mM Gd-DTPA/kg solution. We evaluated the thickness, interruption (or not) of the low signal intensity bands, and enhancement pattern of the cancerous wall and normal gastric wall. We prospectively evaluated the depth of cancer invasion, perigastric infiltration (extraserosal invasion), perigastric organ invasion, and regional lymph nodes and determined tumor staging on MR images. These MR evaluations including MR-determined staging were correlated with the surgicopathologic findings. Results: Stomach cancer was shown as having a thickened wall with a rapid enhancing pattern after intravenous Gd-DTPA administration. The mucosa (and/or submucosa) affected by stomach cancer showed an early enhancement pattern (30–90 s after Gd-DTPA administration) in 43 of 46 patients (93%). The normal gastric mucosa demonstrated a delayed peak enhancement pattern (〉90 s after Gd-DTPA administration) in 29 of 46 patients (63%) and variable enhancement pattern in 17 of 46 patients (37%). An interrupted low signal intensity band or highly enhanced tumorous lesion penetrating through the gastric wall was seen in 17 of 19 pT3 patients (90%). Consistency between MR-determined staging and surgicopathologic staging occurred in three of four pT1 tumors (75%), 10 of 13 pT2 tumors (77%), 17 of 19 pT3 tumors (90%), and eight of 10 pT4 tumors (80%); overall accuracy was 83%. Overall accuracy of regional lymph node involvement, as determined by enhanced MR, was 52%; 24 of 46 node groups were positive. Conclusions: Dynamic and delayed MR imaging can be useful for predicting depth of cancer invasion, perigastric infiltration (extraserosal invasion), and perigastric organ invasion by gastric cancer.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Abdominal imaging 24 (1999), S. 250-257 
    ISSN: 1432-0509
    Keywords: Key words: Liver—Neoplasms—US—CT—MR.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: To verify characteristic features of hepatic dysplastic nodules at different imaging modalities. Methods: Twenty-eight patients with 37 dysplastic nodules of the liver (0.8–3.0 cm) underwent sonography (28 patients), computed tomography (CT; 24 patients), magnetic resonance (MR; 11 patients), and angiography (12 patients). Each nodule was analyzed for echogenicity, attenuation, signal intensity, and vascularity. Results: Echogenicity of nodules was high in 16 (43%), homogeneous in two (6%), and low in 19 (51%) of 37 nodules. Attenuation of nodules was high in one (7%), homogeneous in four (26%), and low in 10 (67%) of 15 nodules on the arterial-phase CT images; homogeneous in five (33%) and low in 10 (67%) of 15 nodules on the portal-phase CT images; and high in four (17%), homogeneous in six (26%), and low in 13 (57%) of 23 nodules on the delayed-phase CT images. Signal intensity of nodules was high in 15 (94%) and homogeneous in one (6%) of 16 nodules on T1-weighted MR images and was homogeneous in seven (44%) and low in nine (56%) of 16 nodules on T2-weighted MR images. Vascularity of nodules was avascular in 14 (88%) and slightly vascular in two (12%) of 16 nodules. Conclusions: Hepatic dysplastic nodules show diverse imaging characteristics with different imaging techniques; however, common imaging findings of hepatic dysplastic nodules are low echo, low attenuation, and high, low, or homogeneous intensity on T1- and T2-weighted MR, and avascularity.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    International journal of cosmetic science 27 (2005), S. 0 
    ISSN: 1468-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Nanoemulsions have recently become increasingly important as potential vehicles for the controlled delivery of cosmetics and for the optimized dispersion of active ingredients in particular skin layers. The preparation of conventional nanoemulsions requires mainly high-pressure homogenization, which is unproductive and requires high energy due to its lower efficiency, limiting their practical applications. In order to solve these problems novel nanoemulsions were studied using a model system of pseudo-ternary water/emulsifier/paraffin oil. Nanoemulsions were prepared by stirring a mixture of the tocopherol-containing block co-polymer emulsifier PPG-20 Tocophereth-50, paraffin oil, and distilled water at the Θ-point using weight fractions of the dispersed phase (φ) of 0.31 to 0.82 and an emulsifier content of 1.0 to 9 wt.%. The emulsifying property of PPG-20 Tocophereth-50 in nanoemulsions was compared with that of the conventional emulsifiers Tocophereth-43, a mixture of polysorbate 60 and sesquioleate (3/1), and phospholipids. Also the emulsifying property of PPG-20 Tocophereth-50 in the more hydrophilic oils caprylic/capric triglyceride and octyldodecanol was compared with that in paraffin oil. The stability and morphology of the resulting nanoemulsions were studied by visual inspection, optical microscopy, particle size analysis, and cryo-scanning electron microscopy. In the nanoemulsion systems containing caprylic/capric triglyceride and octyldodecanol, respectively, as an oil phase PPG-20 Tocophereth-50 showed emulsification properties similar to those in paraffin oil. The conventional emulsifiers Tocophereth-43, a mixture of polysorbate 60 and sesquioleate (3/1), and phospholipids did not give nanoemulsions with high-speed stirring. The block co-polymer nonionic emulsifier PPG-20 Tocophereth-50 was found to produce stable nanoemulsions of mean droplet diameters ranging from 204 to 499 nm. The emulsification method of high-speed stirring at the Θ-point using PPG-20 Tocophereth-50 was found to be very effective for the preparation of stable nanoemulsions useful for applications in skincare cosmetics, cosmeceuticals, and drugs.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Inorganica Chimica Acta 224 (1994), S. 163-169 
    ISSN: 0020-1693
    Keywords: Crystal structures ; Polychalcogenide complexes ; Tellurium complexes
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4139-4147 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dielectric response functions in the valence bands and in the conduction band of heavily doped zincblende semiconductors have been evaluated using the self-consistent field method and incorporating the finite lifetime of particles in the relaxation time approximation. Scattering rates of injected electrons are calculated with the Born approximation in the dielectric response function formalism at finite temperature. The finite particle lifetime introduces significant modifications to the spectral density function {Im[−1/ε(q,ω)]} at small q, where collective excitations (i.e., coupled phonon-plasmon modes) are heavily damped due to collisions. However, these modifications are small at large q. At the same time, the scattering rates of injected electrons are strongly affected by the temperature dependence of these effects, which are particularly significant for p-type semiconductors.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 2282-2287 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper, the commonly used but idealistic formulation of quantized optical-phonon modes for a heterostructure system with only two heterojunctions (i.e., single quantum-well structures) is extended to the more realistic case of multiheterointerface structures. By applying the macroscopic dielectric continuum approach, dispersion relations and interaction Hamiltonians for interface-phonon modes are derived for a double-barrier structure and scattering rates based on these results are used to determine the range of practical validity of the idealistic model using interaction Hamiltonians appropriate for single quantum wells with infinite barrier widths. It is found that when the dimensions of the structures are larger than approximately 30 A(ring), this simplified description can be applied to multiheterointerface structures in general with reasonable accuracy.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3905-3907 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The anharmonic decay of longitudinal-optical (LO) phonons in zinc-blende semiconductors has been studied. Based on an approach in which the anharmonic crystal potential is estimated using the theory of elasticity, the lifetime of LO phonons via emission of two acoustic phonons is calculated as a function of lattice temperature and phonon wave vector. Application of this model to bulk GaAs shows an excellent agreement with available experimental data. Since the parameters employed in the model can be obtained experimentally, the approach provides a useful tool to investigate LO-phonon lifetimes in semiconductors.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2338-2342 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Based on a simplified analysis of perfectly conducting metals, it has been suggested qualitatively that establishing metal-semiconductor interfaces at the heterojunctions of polar semiconductor quantum wells introduces a set of boundary conditions that dramatically reduces or eliminates unwanted carrier energy loss caused by interactions with interface longitudinal-optical (LO) phonon modes. In this article, it is theoretically demonstrated that comparable reductions in LO phonon scattering strengths may be achieved for metal-semiconductor structures with metal having realistic conductivities and Thomas–Fermi screening lengths.
    Type of Medium: Electronic Resource
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