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Omuralide and Vibralactone: Differences in the Proteasome‐ β‐Lactone‐γ‐Lactam Binding Scaffold Alter Target Preferences 下载免费PDF全文
Dr. Nerea Gallastegui Marion Rusch Dr. Christian Hedberg Prof. Dr. Stephan A. Sieber Prof. Dr. Michael Groll 《Angewandte Chemie (International ed. in English)》2014,53(2):571-574
Despite their structural similarity, the natural products omuralide and vibralactone have different biological targets. While omuralide blocks the chymotryptic activity of the proteasome with an IC50 value of 47 nM, vibralactone does not have any effect at this protease up to a concentration of 1 mM . Activity‐based protein profiling in HeLa cells revealed that the major targets of vibralactone are APT1 and APT2. 相似文献
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Rigid, glassy polymers show a diversity of tensile behavior-ranging from apparently brittle to ductile. To delineate some of the factors that control the toughness or impact resistance of these polymers, the yielding behavior of poly (methyl methacrylate) (PMMA) was studied. Results of other workers have shown that the cold flow exhibited by many glassy polymers can be explained qualitatively by a free-volume model. The treatment assumes that molecular flow is permitted when the free volume increase, resulting from the dilatational component of the applied stress, is sufficient to bring the total free volume to that characteristic of the polymer liquid. The present study refines this approach by introducing an “effective temperature,” defined as that hypothetical temperature at which the glass would have an equilibrium free volume equal to the total free volume of the nonequilibrium glass at temperature T. Equations are derived which more satisfactorily describe the temperature and strain-rate dependences of the tensile yield strain of PMMA glass from -10° to 90°C at rates between 0.015 and 120%/sec. 相似文献
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Frontispiece: A Visible Light Photocatalytic Cross‐Dehydrogenative Coupling/Dehydrogenation/6π‐Cyclization/Oxidation Cascade: Synthesis of 12‐Nitroindoloisoquinolines from 2‐Aryltetrahydroisoquinolines 下载免费PDF全文
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Oscillatory structure in the scattered ion yield for He+ scattering from In has been observed to depend upon the chemical environmental of the In. Fourier analysis of the oscillatory structure indicates two major components whose relative amplitudes vary significantly with chemical environment. 相似文献
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The free-volume model for interpreting the initial yielding behavior of glassy polymers is extended to include kinetic energy influences. Molecular mobility is assumed to be determined by the product of the probabilities of attaining sufficient local free volume to allow molecular rearrangement, and kinetic energy to overcome restraining forces. Yielding then is initiated at the point where the free-volume increase resulting from the dilational component of the applied stress is sufficient to bring the local molecular mobility to that characteristic of the unstressed polymer at Tg. Expressions are derived for the temperature and strain-rate dependences of the initial yield strain (defined as the proportional limit on the tensile stress-strain curve) and compared with experimental data for poly(methyl methacrylate). The extended model is found to afford no substantial improvement over a simple free-volume model, indicating that relaxational processes in the glassy state-at least in the range Tg to (Tg - 100°C)-are governed principally by freevolume changes. 相似文献
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Seeding of high temperature air flows is problematic because common seeding materials can ignite and may pose a threat for
human health in case of inhalation. Sodium chloride is proposed as a seeding material to avoid these problems. The generation
of crystals using an ultrasonic atomizer is described and the measured particle size distribution is presented. The described
method has the additional advantage that the particle size can easily be adjusted. This allows the operator to comply with
the experimental requirements in terms of resolvable frequencies. The described method has been successfully applied to LDA
measurements in a 500°C air flow. 相似文献