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  • 1
    Electronic Resource
    Electronic Resource
    Protein dynamics at low temperatures (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 3045-3050 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The low temperature conformational dynamics of the heme type protein mesoporphyrin-IX-substituted horseradish peroxidase is investigated by spectral diffusion waiting time/aging experiments. Spectral diffusion broadening is governed by a power law in time. There is a small but significant aging effect. It is assumed that the conformational dynamics of the protein which leads to the spectral broadening of the burnt-in holes is governed by a diffusion type equation. In this case the shape of the spectral diffusion kernel is Gaussian. This model is contrasted with spectral diffusion phenomena as described by the TLS-model (TLS, two level system). © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480879
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  • 2
    Electronic Resource
    Electronic Resource
    Glasses and proteins: Similarities and differences in their spectral diffusion dynamics (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 8718-8721 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We compare the spectral diffusion dynamics of resorufin doped glycerol/H2O- and glycerol/D2O-glass with the respective dynamics of a chromoprotein in the same glass at 4.2 K. Spectral diffusion broadening of photochemical holes is measured over almost four orders of magnitude in time. In all samples there are strong aging phenomena. Resorufin in deuterated water/glycerol is reasonably well-described by the two level system (TLS) model. In the protonated glass, the TLS model does not seem to describe the experiments reasonably well. In the protein sample it totally fails. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1367382
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of isotopic substitution on the conformational dynamics of frozen proteins (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 9638-9644 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The spectral diffusion dynamics was measured over 3 orders of magnitude in time of a myoglobin-type protein with the heme group substituted by Zn-pheophorbid a. After burning a photochemical hole at 4.2 K, the width of the spectral diffusion kernel is well described by a power law in waiting time with an exponent of 0.24. Spectral diffusion broadening is subject to "aging," viz., to the equilibration time at 4.2 K before hole burning. It decays with a power law in aging time. Deuteration of the solvent has a significant effect on the dynamics of the protein. Spectral diffusion broadening is smaller in the deuterated sample, however, the respective power law is not changed. The aging dynamics, on the other hand, does not seem to be influenced significantly by deuteration. The conclusion is that deuteration influences the fluctuations but not the relaxation. In addition to spectral diffusion, we also measured the recovery dynamics of the hole. It is slowed down tremendously by deuteration, confirming that the photoreaction is based on a light-induced proton transfer. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1369137
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  • 4
    Electronic Resource
    Electronic Resource
    3D numerical simulation of melt flow in the presence of a rotating magnetic field (2000)
    Bradford : Emerald
    International journal of numerical methods for heat & fluid flow 10 (2000), S. 366-384 
    Details
    ISSN: 0961-5539
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Being extensively used in metallurgy, rotating magnetic fields are also becoming increasingly interesting for application in crystal growth, where they are intended to act by stabilizing the melt flow. For this purpose, it is important to understand the basic interactions of the magnetically induced flow and other flow components like time-dependent buoyant convection. So a three-dimensional finite volume method was developed in order to numerically study the effect of a rotating magnetic field on convection in a cylindrical melt volume. The equations of mass, momentum, and heat transport are solved together with the potential equations describing the electromagnetic field. The numerical computation of the Lorenz force distribution is validated by comparison with an analytical solution. The effects of magnetic field parameters on the temperature distributions and the flow patterns in the considered configurations are analysed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/09615530010327369
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  • 5
    Electronic Resource
    Electronic Resource
    Early stages of mechanical crystallization of amorphous FeZrBCu soft magnetic material (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 2464-2468 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nanocrystalline Fe-base soft magnetic materials with high saturation magnetization have been obtained by crystallization of FeZrBCu amorphous precursors. In contrast to the conventional thermal crystallization, mechanical crystallization provides an alternative route for the generation of nanocrystalline materials using a high energy ball mill. Special emphasis is put here on the early stages of the transformation. X-ray diffraction, Mössbauer spectroscopy, and magnetization measurements are used to characterize the material. We find a continuous increase of the saturation magnetization accompanied by an increase of the crystalline fraction. The coercivity shows a different behavior with a large increase after very short milling within the amorphous state and a decrease for long milling duration. The influence of the deformation process on the magnetic anisotropy and the coercivity is discussed in terms of stresses and shear band formation. The results are compared with the phase formation and magnetic properties of thermally crystallized FeZrBCu samples and mechanical crystallization studies of other materials. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372203
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  • 6
    Electronic Resource
    Electronic Resource
    The SCHIZOID gene regulates differentiation and cell division in Arabidopsis thaliana shoots (2000)
    Springer
    Planta 211 (2000), S. 34-42 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Arabidopsis (shz-2 mutant) – Differentiation – Meristem – Mutant Arabidopsis– Shoot apex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract.  Cell division and cell differentiation are key processes in shoot development. The Arabidopsis thaliana (L.) Heynh. SCHIZOID (SHZ) gene appears to influence cell differentiation and cell division in the shoot. The shz-2 mutant is notable in that distinct phenotypes develop, depending on the environment in which the plants are grown. When shz-2 mutants are grown in petri dishes, callus develops from the petiole and hypocotyl. In contrast, when the mutants are grown on soil, shoots appear externally stunted with malformed leaves. However, detailed examination of soil-grown mutants shows that the two phenotypes are related. Soil-grown mutants form adventitious meristems, produce a large amount of vascular tissues and have aberrant cell divisions in the meristem. Cells with abnormal cell-division patterns were found in the apical and vascular meristems, suggesting SHZ influences cell division. Development of callus in petri dishes, development of adventitious meristems and aberrations in leaves on soil suggest that SHZ influences cell differentiation. The distinct, but related phenotypes on soil and in petri dishes suggests that SHZ normally functions to regulate differentiation and/or cell division in a manner that is responsive to environmental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250000255
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  • 7
    Electronic Resource
    Electronic Resource
    Langzeitverlauf nach Gallengangverletzung durch laparoskopische Cholecystektomie und Rekonstruktion durch ein Jejunuminterponat (2000)
    Springer
    Der Chirurg 71 (2000), S. 1500-1503 
    Details
    ISSN: 1433-0385
    Keywords: Keywords: Bile duct injury – Laparoscopic cholecystectomy – Jejunal conduit. ; Schlüsselwörter: Gallengangverletzung – laparoskopische Cholecystektomie – Jejunuminterponat.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Im Krankheitsverlauf von Patienten mit schweren Gallengangverletzungen im Rahmen einer laparoskopischen Cholecystektomie werden oft sekundäre Komplikationen beobachtet. Berichtet wird über eine Patientin mit langem Krankheitsverlauf nach intraoperativer Gallengangverletzung und anschließender Rekonstruktion durch End-zu-End-Anastomose über einer T-Drainage. Mehr als 5 Jahre nach wiederholten endoskopischen Gallenwegdilatationen und mehrfachen Einlagen von Stents wurde zuletzt ein selbstexpandierender Metallgitterstent eingesetzt. Die Symptomatik mit rezidivierenden Cholestasen und Cholangitiden wurde nicht beherrscht. Bei der erneuten Operation wurde jetzt der stenttragende D. choledochus reseziert, die Gallenwegrekonstruktion erfolgte durch ein isoperistaltisches Jejunuminterponat. Mehr als 24 Monate später ist die Patientin beschwerdefrei und arbeitet wieder.
    Notes: Abstract. The follow-up of patients with severe bile duct lesions after laparoscopic cholecystectomy often shows secondary complications. We report on a female patient suffering from long-lasting complications after bile duct injury and early reconstruction by end-to-end anastomosis via a T-tube drainage. More than 5 years later and after multiple dilatation and stenting of the bile duct stenosis the patient was treated with an expanding metal stent. The severe cholangitis persisted. So the patient was operated on: bile duct and connected stent were resected. The reconstruction was performed with an isoperistaltic jejunal conduit. More than 24 months later the patient is healthy and at work again.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001040051251
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  • 8
    Electronic Resource
    Electronic Resource
    Measurement of GEp/GMp via polarization transfer at Q2 = 0.4 GeV /c2 (2001)
    Springer
    The European physical journal 12 (2001), S. 125-127 
    Details
    ISSN: 1434-601X
    Keywords: PACS. 25.30.Bf Elastic electron scattering – 13.40.Gp Electromagnetic form factors – 14.20.Dh Protons and neutrons – 24.70.+s Polarization phenomena in reactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The polarization transfer from longitudinally polarized electrons to protons in the elastic scattering p( e, e' p) has been measured around Q2 = 0.4 (GeV/c)2 with the three-spectrometer facility at the Mainz microtron MAMI. From this polarization transfer the ratio G Ep/(G Mp/μp) has been determined. The ratio is found to be slightly less than unity in agreement with recent results from other laboratories and from the Rosenbluth separation of cross-sections measured with unpolarized electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500170046
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  • 9
    Electronic Resource
    Electronic Resource
    Keratinase of Doratomyces microsporus (2000)
    Springer
    Applied microbiology and biotechnology 53 (2000), S. 196-200 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The fungus Doratomyces microsporus produced an extracellular keratinase during submerged aerobic cultivation in a medium containing a protein inducer for enzyme synthesis. The keratinase was purified to homogeneity using hydrophobic interaction chromatography followed by gel chromatography. The molecular weight was estimated to be 33 kDa (from SDS-PAGE analysis) or 30 kDa (by gel chromatography), suggesting a monomeric structure. The isoelectric point of the enzyme was determined to be around 9. The optimal pH and temperature for keratinolytic activity were pH 8–9 and 50 °C, respectively. The serine protease inhibitor PMSF totally inhibited the keratinase. The enzyme was not glycosylated. It was capable of hydrolysing different keratinous materials as well as some non-keratinous proteins. Hydrolysis of some synthetic substrates, specific for known proteinases, suggested that the keratinase of D. microsporus is close to proteinase K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050008
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