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排序方式: 共有264条查询结果,搜索用时 15 毫秒
91.
Steinberg MZ Elber R McLafferty FW Gerber RB Breuker K 《Chembiochem : a European journal of chemical biology》2008,9(15):2417-2423
Electrospray ionization transfers thermally labile biomolecules, such as proteins, from solution into the gas phase, where they can be studied by mass spectrometry. Covalent bonds are generally preserved during and after the phase transition, but it is less clear to what extent noncovalent interactions are affected by the new gaseous environment. Here, we present atomic-level computational data on the structural rearrangement of native cytochrome c immediately after solvent removal. The first structural changes after desolvation occur surprisingly early, on a timescale of picoseconds. For the time segment of up to 4.2 ns investigated here, we observed no significant breaking of native noncovalent bonds; instead, we found formation of new noncovalent bonds. This generally involves charged residues on the protein surface, resulting in transiently stabilized intermediate structures with a global fold that is essentially the same as that in solution. Comparison with data from native electron capture dissociation experiments corroborates both its mechanistic postulations and our computational predictions, and suggests that global structural changes take place on a millisecond timescale not covered by our simulations. 相似文献
92.
Vaults are ubiquitous, self-assembled protein nanocapsules with dimension in the sub-100 nm range that are conserved across diverse phyla from worms to humans. Their normal presence in humans at a copy number of over 10,000/cell makes them attractive as potential drug delivery vehicles. Toward this goal, bifunctional amine-reactive reagents are shown to be useful for the reversible cross-linking of recombinant vaults such that they may be closed and opened in a controllable manner. 相似文献
93.
Scott D. Kelman Roy D. Raharjo Christopher W. Bielawski Benny D. Freeman 《Polymer》2008,49(13-14):3029-3041
Crosslinking poly[1-(trimethylsilyl)-1-propyne] (PTMSP) films with 3,3′-diazidodiphenylsulfone, a bis(azide) crosslinker, rendered the films insoluble in common solvents for PTMSP such as toluene. At all temperatures, mixed gas CH4 and n-C4H10 permeabilities of crosslinked PTMSP were less than those of uncrosslinked PTMSP, which correlates with lower free volume in the crosslinked material. The presence of fumed silica (FS) nanoparticles in both uncrosslinked PTMSP and crosslinked PTMSP increased mixed gas CH4 and n-C4H10 permeabilities, consistent with the disruption of polymer chain packing by such nanoparticles. Mixed gas CH4 permeabilities of all films were significantly less than their corresponding pure gas CH4 permeabilities. For example, at 35 °C, the mixed gas CH4 permeabilities were approximately 60–80% less than their pure gas values. The greatest decrease was observed for uncrosslinked PTMSP, while nanocomposite PTMSP films showed the least decrease. The mixed gas n-C4H10/CH4 selectivities of crosslinked PTMSP and nanocomposite PTMSP films were less than those of uncrosslinked PTMSP at all temperatures. For example, at 35 °C, the mixed gas n-C4H10/CH4 selectivities of uncrosslinked PTMSP, crosslinked PTMSP containing 10 wt% crosslinker, and uncrosslinked PTMSP containing 30 wt% FS were 33, 27, and 17, respectively, when the feed gas contained 2 mol% n-C4H10 and the total upstream mixture fugacity was 11 atm. For all films, as temperature decreased, mixed gas n-C4H10 permeabilities increased, and mixed gas CH4 permeabilities decreased. Consequently, the mixed gas n-C4H10/CH4 selectivities increased substantially as temperature decreased and the mixed gas selectivity of uncrosslinked PTMSP increased from 33 to 170 as temperature decreased from 35 °C to ?20 °C when the feed gas contained 2 mol% n-C4H10 and the total upstream mixture fugacity was 11 atm. 相似文献
94.
Benny Bøhm 《Fire Technology》1978,14(3):239-246
Every building should be executed and arranged in such a way or by the use of such materials that, taking into consideration its purpose and location, it will give reasonable fire safety for persons staying in the building, including proper facilities for saving the occupants and for fire extinguishment to be carried out, and also to give reasonable safety against spread of fire to adjoining buildings and activities on adjoining sites. — Danish Building Code, Chapter 6.1.1
Note: The material properties of the compartments are defined in References 3 and 4. A black furnace refers to a furnace in which the incident flux is equal toT
gas
4. 相似文献
95.
Benny Y Manzanera S Prieto PM Ribak EN Artal P 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(6):1538-1544
The human eye is affected by large chromatic aberration. This may limit vision and makes it difficult to see fine retinal details in ophthalmoscopy. We designed and built a two-triplet system for correcting the average longitudinal chromatic aberration of the eye while keeping a reasonably wide field of view. Measurements in real eyes were conducted to examine the level and optical quality of the correction. We also performed some tests to evaluate the effect of the corrector on visual performance. 相似文献
96.
Energetic materials - explosives, thermites, populsive powders - are used in a variety of military and civilian applications. Their mechanical and electrostatic sensitivity is high in many cases, which can lead to accidents during handling and transport. These considerations limit the practical use of some energetic materials despite their good performance. For industrial applications, safety is one of the main criteria for selecting energetic materials. The sensitivity has been regarded as an intrinsic property of a substance for a long time. However, in recent years, several approaches to lower the sensitivity of a given substance, using nanotechnology and materials engineering, have been described. This feature article gives an overview over ways to prepare energetic (nano-)materials with a lower sensitivity. 相似文献
97.
We consider pseudorandom generators in which each output bit depends on a constant number of input bits. Such generators have appealingly simple structure: They can be described by a sparse input–output dependency graph \(G\) and a small predicate \(P\) that is applied at each output. Following the works of Cryan and Miltersen (MFCS’01) and by Mossel et al (STOC’03), we ask: which graphs and predicates yield “small-bias” generators (that fool linear distinguishers)? We identify an explicit class of degenerate predicates and prove the following. For most graphs, all non-degenerate predicates yield small-bias generators, \(f:\{0,1\}^n \rightarrow \{0,1\}^m\), with output length \(m = n^{1 + \epsilon }\) for some constant \(\epsilon > 0\). Conversely, we show that for most graphs, degenerate predicates are not secure against linear distinguishers, even when the output length is linear \(m=n+\Omega (n)\). Taken together, these results expose a dichotomy: Every predicate is either very hard or very easy, in the sense that it either yields a small-bias generator for almost all graphs or fails to do so for almost all graphs. As a secondary contribution, we attempt to support the view that small-bias is a good measure of pseudorandomness for local functions with large stretch. We do so by demonstrating that resilience to linear distinguishers implies resilience to a larger class of attacks. 相似文献
98.
Steven Wang Woo Jin Lee Chao'en Li Benny Kuan Nick Burke Jim Patel 《American Institute of Chemical Engineers》2019,65(3):1035-1046
This study of methane pyrolysis was designed to look at carbon deposition on the internal reactor and wafer surface during CH4 pyrolysis. The rate of carbon deposition on the internal reactor surfaces could be reduced with: lower methane/oxygen ratios, shorter residence times, and lower temperatures. The type of carbon formed appeared to have a significant effect on the pyrolysis process. Pyrolytic carbon with a lower order structure produces a higher selectivity for carbon formation compared to carbon with a higher order structure. Form a process perspective, there are two obvious means of addressing this: deposited carbon could be regularly removed; and/or pyrolysis conditions are selected that produce carbon with a higher order structure. From the results, it is very clear that any development of a commercial process for natural gas pyrolysis in ceramic reactor systems would have to carefully address the selection of reactor material. © 2018 American Institute of Chemical Engineers AIChE J, 65: 1035–1046, 2019 相似文献
99.
Benny HartonoPeter Heidebrecht Kai Sundmacher 《International Journal of Hydrogen Energy》2011,36(12):7240-7250
We investigate the utilization of anode exhaust gas from high temperature fuel cells as gasification or reforming agent in Solid Oxide Fuel Cell (SOFC) and Molten Carbonate Fuel Cell (MCFC) power plants. The minimal anodic recirculation ratio is determined by two approaches: based on stoichiometric considerations and using detailed modeling of all process units. In the latter case, the risk of carbon formation and system heat integration are considered. The results indicate that the stoichiometric approach can be used as a shortcut method only for the SOFC systems due to good agreements with the detailed calculations. Furthermore, the mass integration concept is a feasible option for a wide variety of fuels in SOFC plants thanks to their relatively high operating temperatures. In MCFC systems, significantly higher recycle ratios are required to suppress carbon deposition which makes this concept unattractive. 相似文献
100.
Benny Joseph K G Gopchandran P K Manoj Peter Koshy V K Vaidyan 《Bulletin of Materials Science》1999,22(5):921-926
Zinc oxide thin films were prepared on glass substrates from an aqueous solution of zinc acetate by spray pyrolysis. These
films were characterized using X-ray diffraction, scanning electron microscopy and optical transmission. The films were highly
transparent to the visible radiation and electrically conductive. Films deposited at optimum conditions exhibited a resistivity
of 3·15×10−3 Ωm along with a transmittance of 98% at 550 nm. 相似文献