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  • 1
    Electronic Resource
    Electronic Resource
    Purification, characterization, and primary structure of a chitinase from Pseudomonas sp. YHS-A2 (2000)
    Springer
    Applied microbiology and biotechnology 54 (2000), S. 397-405 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A chitinase gene (chiA) from Pseudomonas sp. YHS-A2 was cloned into Escherichia coli using pUC19. The nucleotide sequence determination revealed a single open reading frame of chiA comprised of 1902 nucleotide base pairs and 633 deduced amino acids with a molecular weight of 67,452 Da. Amino acid sequence alignment showed that ChiA contains two putative chitin-binding domains and a single catalytic domain. Two proline-threonine repeat regions, which are linkers between catalytic and substrate-binding domains in some cellulases and xylanases, were also found. From E. coli, ChiA was purified 12.8-fold relative to the periplasmic fraction. The Michaelis constant and maximum initial velocity for p-nitrophenyl-N,N′-diacetylchitobiose were 1.06 mM and 44.4 μmol/h per mg protein, respectively. The purified ChiA binds not only to colloidal chitin but also to other substrates (avicel, chitosan, and xylan), but the binding affinity of avicel, chitosan, and xylan is around 10 times lower than that of colloidal chitin. The reaction of ChiA with colloidal chitin and chitooligosaccharides (trimer-hexamer) produced an end product of N,N′-diacetylchitobiose, indicating that ChiA is a chitobiosidase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530000408
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  • 2
    Electronic Resource
    Electronic Resource
    Radiation enhanced diffusion of Ti in Al2O3 (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 5058-5064 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Titanium bulk and dislocation diffusion coefficients at 1000 °C have been determined for Ti in single crystal α-Al2O3(0001) for three types of samples: (i) Ti evaporated onto Al2O3, (ii) 48Ti+at 100 eV deposited onto Al2O3, and (iii) 48Ti+ at 100 eV deposited onto radiation damaged Al2O3 (damage inflected by implantation of 46Ti+ at 7 keV). Diffusion penetration profiles were obtained by using secondary ion mass spectrometry depth profiling techniques. For the deposited and implanted Ti+ samples, the bulk diffusion coefficients (D) are 5.4×10−21 and 5.6×10−17 m2 s−1, respectively, and dislocation diffusion coefficients are 3.6×10−17 and 1.4×10−12 m2 s−1, respectively. Comparing the D's for Ti in the undamaged and damaged Al2O3, the D's for the latter samples are higher by a factor of 104–105, reflecting the radiation enhanced diffusion due to the defect structure inflected by the implanted 7 keV 46Ti+. Comparing the D's for Ti deposited onto Al2O3 (both the evaporated and 100 eV 48Ti+ samples) with those for Cr deposited onto Al2O3, the Ti D's are larger by a factor of 10, reflecting the influence of the valence state of the cation. These results show that cationic diffusion coefficients in Al2O3 can be controlled by varying the level of defects in the crystal. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1286222
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  • 3
    Electronic Resource
    Electronic Resource
    Expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in human crescentic glomerulonephritis (2002)
    Oxford, UK : Blackwell Science Ltd
    Histopathology 41 (2002), S. 0 
    Details
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in human crescentic glomerulonephritisAims:  In glomerulonephritis, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) may play important roles in the formation of crescents. These studies are designed to evaluate the expression patterns of ICAM-1 and VCAM-1 in human crescentic glomerulonephritis and to determine the cellular origin of adhesion molecules in the crescentic lesions.Methods and results:  We examined the expression of ICAM-1 and VCAM-1 proteins in renal biopsies with cellular (n=7), fibrocellular (n=9) or fibrous (n=4) crescentic glomerulonephritis, and six controls by immunohistochemistry. mRNA expression of ICAM-1 and VCAM-1 was further evaluated by RNA in-situ hybridization. Cytokeratin or CD68 immunohistochemistry was performed on the same sections, where in-situ hybridization had been carried out. In cellular crescents, ICAM-1 and VCAM-1 proteins were over-expressed to a similar extent. Of the three types of crescents, the extent of ICAM-1 immunopositivity was the greatest in the cellular crescents and decreased towards the fibrous crescents (P 〈 0.05). Yet the extent of VCAM-1 immunoreactivity was not different between the types. Fibrous crescents still contained some epithelial cells and showed only VCAM-1 expression. In the glomeruli with cellular or fibrocellular crescents, the extent of ICAM-1 immunopositivity in the glomerular tufts was significantly larger than that of VCAM-1 (P 〈 0.05). In an in-situ hybridization study, the mRNA expression patterns of ICAM-1 and VCAM-1 paralleled their protein expressions. A double-labelling study showed that the signal for ICAM-1 and VCAM-1 mRNAs was mainly present in cytokeratin-positive and CD68-negative cells in the crescentic lesions.Conclusions:  These results suggest that glomerular parietal epithelial cells in cellular crescents up-regulate both ICAM-1 and VCAM-1, and that some epithelial cells retained in fibrous crescents persistently over-express VCAM-1, but not ICAM-1. They also suggest that ICAM-1 is involved in early leucocyte recruitment into glomeruli in crescentic glomerulonephritis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2559.2002.01446.x
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  • 4
    Electronic Resource
    Electronic Resource
    Alteration of E-cadherin-mediated adhesion protein is common, but microsatellite instability is uncommon in young age gastric cancers (2003)
    Oxford, UK : Blackwell Science Ltd
    Histopathology 42 (2003), S. 0 
    Details
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aims:  Gastric adenocarcinoma in young patients has been considered to differ in many ways from gastric carcinoma in older patients. This study was designed to determine the clinicopathological features and molecular mechanisms.Methods and results:  Based on 4123 patients of gastric cancer in Seoul National University Hospital, 135 patients (3.3%) were chosen by the age of 30 years or younger. Expression of E-cadherin, β-catenin, p53 and Epstein–Barr virus (EBV) was analysed using the tissue array method in formalin-fixed paraffin-embedded specimens and microsatellite instability (MSI) was determined. As a control, 320 cases of older patients were compared. Gastric adenocarcinoma of young patients revealed significant female predominance, type IV gross type, proximal location, diffuse type and frequent lymph node metastasis. In-situ hybridization for EBV showed higher positivity in young patients (9/78, 11.5%) than in older ones, but not statistically significant. In EBV+ cases, p53 over-expression was significantly higher in young patients than older patients (P 〈 0.05). Alteration of E-cadherin or β-catenin was significantly higher in younger patients than in older patients (P 〈 0.05). Overall survival was significantly poorer in younger patients than older ones. The frequency of MSI was rare (1.3%, P 〈 0.05) in young patients compared with older patients (9.3%).Conclusions:  These data indicate that gastric adenocarcinoma of young patients has a poor prognosis, possesses aggressive histopathological features, exhibits reduced expression of E-cadherin and β-catenin, and demonstrates lower MSI than tumours in older patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2559.2003.01546.x
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  • 5
    Electronic Resource
    Electronic Resource
    Estimating the model parameters of deep-level transient spectroscopy data using a combined wavelet/singular value decomposition Prony method (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 1800-1805 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article, a combined wavelet/singular value decomposition-Prony method to estimate the time constants associated with deep-level transient spectroscopy data is presented. A filtering scheme based on wavelet denoising is used to provide a preprocessing technique that allows the singular value decomposition-Prony method to be applied to transient capacitance data to accurately estimate the associated time constants. Results for both simulated multiple exponential model data with additive white-Gaussian noise and real transient spectroscopy data are presented to illustrate the applicability of the presented technique. Furthermore, the concept of detecting multiple time constants is investigated and a statistical analysis is performed to address the constraints associated with the presented technique to achieve effective detection and estimation. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1340028
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  • 6
    Electronic Resource
    Electronic Resource
    Simultaneous existence and atomic arrangement of CuPt-type and CuAu-I type ordered structures near ZnTe/ZnSe heterointerfaces (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5657-5660 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Selected area electron diffraction pattern and high-resolution transmission electron microscopy measurements on a ZnTe/ZnSe heterointerface grown on a GaAs(001) substrate showed two structures of the CuPtB-type ordering structures, one for each direction of the doublet periodicity on the {111} lattice planes along the [110] axis, and superstructure spots related to CuAu-I-type ordering. Auger electron spectroscopy measurements showed that the Se atoms were interdiffused into the ZnTe thin film and that the diffused Se atoms formed a ZnSexTe1−x layer, which might be related to the coexistence of the two types of ordered structures. The coexisting behavior of the two ordered structures are discussed. The present results can help improve the understanding of the formation mechanism and the coexisting behaviors of the two ordered structure near the ZnTe/ZnSe heterointerface. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1459744
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  • 7
    Electronic Resource
    Electronic Resource
    Microstructural and optical properties of InAs/GaAs quantum dots embedded in modulation-doped AlxGa1−xAs/GaAs heterostructures (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5195-5199 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructural and the optical properties of InAs/GaAs quantum-dot (QD) arrays inserted into undoped GaAs barriers embedded in an AlxGa1−xAs/GaAs were investigated by using transmission electron microscopy (TEM) and photoluminescence (PL) measurements. The TEM images and the selected-area electron diffraction patterns showed that vertically stacked InAs QD self-assembled arrays were embedded in the GaAs barriers. The temperature-dependent PL spectra showed that the peak corresponding to the interband transitions from the ground electronic subband to the ground heavy-hole band of the InAs QDs shifted to lower energy with increasing temperature. The PL intensity of the InAs dots was significantly enhanced by the modulation-doped AlxGa1−xAs/GaAs heterostructure, and the thermal activation energy of the InAs dots was decreased by the addition of the modulation-doped AlxGa1−xAs/GaAs heterostructure. The present results can help to improve the understanding of the microstructural and the optical properties in InAs QD arrays inserted into GaAs barriers embedded in a modulation-doped AlxGa1−xAs/GaAs heterostructure. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1459752
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  • 8
    Electronic Resource
    Electronic Resource
    Existence and atomic arrangement of the CuPt-type ordered structure near the ZnTe/GaAs heterointerface due to residual impurities (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 4027-4031 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transmission electron microscopy (TEM) and selected area electron diffraction pattern (SADP) measurements were carried out to investigate the ordered structures near ZnTe/GaAs heterointerfaces, and Auger electron spectroscopy (AES) and secondary ion mass spectroscopy (SIMS) measurements were performed to determine the compositions of the ZnTe/GaAs interfacial layer. The SADP showed two sets of {〈fraction SHAPE="CASE"〉12 〈fraction SHAPE="CASE"〉12 〈fraction SHAPE="CASE"〉12} extra spots with symmetrical intensity, and the corresponding high-resolution TEM image showed doublet periodicity in contrast of the {111} lattice planes. The results of the SADP and the high-resolution TEM measurements showed that a CuPt-type ordered (Cd, Zn)Te structure was observed near the ZnTe/GaAs heterointerface, and the AES and SIMS results showed that the ordered structure was formed due to the diffusion of Cd atoms into the ZnTe layer. Two variants, one for each direction of the doublet periodicity on the {111} lattice, were observed in the ordering, and each variant had its own domain structure with a similar probability. The formation of the CuPt-type ordered structure near the ZnTe/GaAs heterointerface originated from both the existence of the Cd residual impurities during the initial growth stage of the ZnTe epilayer and the strain relaxation of the ZnTe epilayer. These results can help to improve the understanding of the microstructural properties of the ZnTe/GaAs heterointerface. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1405820
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  • 9
    Electronic Resource
    Electronic Resource
    Coexistence behavior of the CuPtB-type and the CuAu–I-type ordered structures in highly strained CdxZn1−xTe/GaAs heterostructures (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1637-1639 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ordered structures in highly strained CdxZn1−xTe/GaAs heterostructures epitaxial layers grown on (001)GaAs substrates were investigated by using selected area electron diffraction pattern (SADP) and cross-sectional high-resolution transmission electron microscopy (HRTEM) measurements. The SADP results showed two sets of (1/2 1/2 1/2) superstructure reflections with symmetrical intensities along the [110] axis, and the corresponding HRTEM images indicated a doublet periodicity in the contrast of the {111} lattice planes. Two structures, one corresponding to the CuPtB-type ordering for each direction of the doublet periodicity on the {111} lattice planes along the [110] axis and the other corresponding to superstructure spots related to the CuAu–I type ordering were observed in the SADP. The doublet periodicity of 200 lattice fringes, associated with the CuAu–I-type ordered structure was also observed in the HRTEM image, and many antiphase boundaries were observed in ordered regions. The formation of the two ordered structures in the CdxZn1−xTe epilayers might originate from the minimization of the relaxation energy due to the high strain effect resulting from the large lattice mismatch between the CdxZn1−xTe epilayer and the GaAs substrate. These results provide important information on the microstructural properties for improving the efficiencies of CdxZn1−xTe-based optoelectronic devices operating in the blue-green spectral region. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1398617
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  • 10
    Electronic Resource
    Electronic Resource
    Transient breakdown behavior in electron-irradiated and proton-irradiated silicon p–n junctions (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 888-890 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We studied the turn-off transient behavior of electron- and proton-irradiated silicon p–n junction diodes. Electron-irradiated n+–p diodes showed transient current peaks at lower reverse voltages. When the forward current was increased, the height and the number of the peaks increased, and at each peak the diode voltage showed a sharp decrease. We explain that the increased ionization coefficients by the electron irradiation caused the current peak to appear during the turn-off transients. p+–n diodes irradiated under the same condition did not show the large peak. This suggests that only the defects in the p-type silicon are responsible for the current peaks. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125619
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