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991.
Tischler JZ Eres G Larson BC Rouleau CM Zschack P Lowndes DH 《Physical review letters》2006,96(22):226104
We use time-resolved surface x-ray diffraction measurements with microsecond range resolution to study the growth kinetics of pulsed laser deposited . Time-dependent surface coverages corresponding to single laser shots were determined directly from crystal truncation rod intensity transients. Analysis of surface coverage evolution shows that extremely fast nonequilibrium interlayer transport, which occurs concurrently with the arrival of the laser plume, dominates the deposition process. A much smaller fraction of material, which is governed by the dwell time between successive laser shots, is transferred by slow, thermally driven interlayer transport processes. 相似文献
992.
Claude A. Pruneau 《Acta Physica Hungarica A》2006,25(2-4):401-408
We present measurements of dynamical net charge fluctuations in Au+Au collisions at $\sqrt {s_{NN} } = 20$ , 62, 130 and 200 GeV using the measure ν +?,dyn. We observe the dynamical fluctuations are finite at all energies, and do not exhibit dependence on beam energy. We find net charge fluctuations violate the trivial 1/N scaling expected for nuclear collisions consisting of independent nucleon-nucleon interactions. We also find dynamical fluctuations exhibit sizable dependence of the pseudo-rapidity and azimuthal ranges of integration. We compare measured data with transport models and a toy model invoking radial flow, and show the bulk of the measured correlations can be accounted for by resonance production and radial collective flow. 相似文献
993.
Andreas Christoforow Julian Wilke Aylin Binici Axel Pahl Claude Ostermann Sonja Sievers Herbert Waldmann 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14857-14865
Natural products (NPs) inspire the design and synthesis of novel biologically relevant chemical matter, for instance through biology‐oriented synthesis (BIOS). However, BIOS is limited by the partial coverage of NP‐like chemical space by the guiding NPs. The design and synthesis of “pseudo NPs” overcomes these limitations by combining NP‐inspired strategies with fragment‐based compound design through de novo combination of NP‐derived fragments to unprecedented compound classes not accessible through biosynthesis. We describe the development and biological evaluation of pyrano‐furo‐pyridone (PFP) pseudo NPs, which combine pyridone‐ and dihydropyran NP fragments in three isomeric arrangements. Cheminformatic analysis indicates that the PFPs reside in an area of NP‐like chemical space not covered by existing NPs but rather by drugs and related compounds. Phenotypic profiling in a target‐agnostic “cell painting” assay revealed that PFPs induce formation of reactive oxygen species and are structurally novel inhibitors of mitochondrial complex I. 相似文献
994.
Yong Hu Maximilian Grsche Sahana Sheshachala Claude Oelschlaeger Norbert Willenbacher Kersten S. Rabe Christof M. Niemeyer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(48):17429-17432
Although DNA nanotechnology has developed into a highly innovative and lively field of research at the interface between chemistry, materials science, and biotechnology, there is still a great need for methodological approaches for bridging the size regime of DNA nanostructures with that of micrometer‐ and millimeter‐sized units for practical applications. We report on novel hierarchically structured composite materials from silica nanoparticles and DNA polymers that can be obtained by self‐assembly through the clamped hybridization chain reaction. The nanocomposite materials can be assembled into thin layers within microfluidically generated water‐in‐oil droplets to produce mechanically stabilized hollow spheres with uniform size distributions at high throughput rates. The fact that cells can be encapsulated in these microcontainers suggests that our concept not only contributes to the further development of supramolecular bottom‐up manufacturing, but can also be exploited for applications in the life sciences. 相似文献
995.
Acidic cyclization of either the diethylallylamines 29b or 30 , followed by a 1.5 mol‐% Pd‐catalyzed carbomethoxylation of quaternized 31b , leads to the methyl ester 36a . This latter could also be obtained in optically pure form by carbomethoxylation of the corresponding (+)‐acetate. Final reduction‐cyclization may be conducted as earlier described, towards the desired odoriferous rac‐Ambrox® 38a , or its pure (?)‐enantiomer. Generation of a π‐allyl Pd complex from an allylic ammonium salt, followed by carboalkoxylation is novel. In only five chemical steps starting from farnesene 2 , the present work constitutes the most concise total synthesis of rac‐Ambrox® 38a to date. 相似文献
996.
Wire Rope Isolators (WRI) are well known and used for the protection of sensitive equipment against non-contact underwater explosions (UNDEX) on board Naval Ships, amongst others, which are extremely destructive and can comple`tely impair the ship’s combat capability.
Traditional WRI exhibit a number of definite advantages, such as large deflection capability, modularity and insensitivity to aggressive environment when proper materials are used. However, their inherent nonlinearity does not always provide the best solution in terms of shock attenuation. (Stiffening tension characteristics)
Fortunately, there are ways to overcome this problem, namely increasing their damping and/ or changing their aspect ratio. It is the purpose of this presentation to show how to overcome this problem and through analysis, by use of validated models of the shock testing machines. The existing technology will be briefly presented and HDWRI (high damping wire rope isolators) vs. conventional WRI responses will be compared on the US Navy shock testing machines of MIL-S-901D.
The US Navy standard MIL-S-901 defines a physical shock testing machine to impact the target before its approval. Different testing machines are used (LWSM, MWSM, FSP, and new DSSM) depending on the weight and size of the target, and on the deck frequency simulated.
The Socitec Group has developed a full model of the various shock testing machines using its in-house developed SYMOS software package. Currently, the Group is in the process of completing a model for the DSSM. 相似文献
Traditional WRI exhibit a number of definite advantages, such as large deflection capability, modularity and insensitivity to aggressive environment when proper materials are used. However, their inherent nonlinearity does not always provide the best solution in terms of shock attenuation. (Stiffening tension characteristics)
Fortunately, there are ways to overcome this problem, namely increasing their damping and/ or changing their aspect ratio. It is the purpose of this presentation to show how to overcome this problem and through analysis, by use of validated models of the shock testing machines. The existing technology will be briefly presented and HDWRI (high damping wire rope isolators) vs. conventional WRI responses will be compared on the US Navy shock testing machines of MIL-S-901D.
The US Navy standard MIL-S-901 defines a physical shock testing machine to impact the target before its approval. Different testing machines are used (LWSM, MWSM, FSP, and new DSSM) depending on the weight and size of the target, and on the deck frequency simulated.
The Socitec Group has developed a full model of the various shock testing machines using its in-house developed SYMOS software package. Currently, the Group is in the process of completing a model for the DSSM. 相似文献
997.
998.
利用超简谐振动近似的有效二阶微扰法(VPT2)和变异微扰法(VCI-P)两种静态方法,以及在300和600K下的密度泛函分子动态轨线振动分析方法进行量子力学的振动计算. 比较了这四种方法对于基频跃迁频率和对应的中红外光谱在相同的B3LYP/6-31+G(d,p)基组描述电子结构前提下所得到的计算结果. 总结了对于半刚性和柔性分子的主要结果,并且对这些计算方法的优缺点进行了比较. 相似文献
999.
Didjour Albert Kambir Jean Brice Boti Ahmont Claude Landry Kablan Daouda Ballo Mathieu Paoli Virginie Brunini Flix Tomi 《Molecules (Basel, Switzerland)》2021,26(20)
The chemical variability and the in vitro anti-inflammatory activity of the leaf essential oil from Ivorian Isolona dewevrei were investigated for the first time. Forty-seven oil samples were analyzed using a combination of CC, GC(RI), GC-MS and 13C-NMR, thus leading to the identification of 113 constituents (90.8–98.9%). As the main components varied drastically from sample to sample, the 47 oil compositions were submitted to hierarchical cluster and principal components analyses. Three distinct groups, each divided into two subgroups, were evidenced. Subgroup I−A was dominated by (Z)-β-ocimene, β-eudesmol, germacrene D and (E)-β-ocimene, while (10βH)-1β,8β-oxido-cadina-4-ene, santalenone, trans-α-bergamotene and trans-β-bergamotene were the main compounds of Subgroup I−B. The prevalent constituents of Subgroup II−A were germacrene B, (E)-β-caryophyllene, (5αH,10βMe)-6,12-oxido-elema-1,3,6,11(12)-tetraene and γ-elemene. Subgroup II−B displayed germacrene B, germacrene D and (Z)-β-ocimene as the majority compounds. Germacrene D was the most abundant constituent of Group III, followed in Subgroup III−A by (E)-β-caryophyllene, (10βH)-1β,8β-oxido-cadina-4-ene, germacrene D-8-one, and then in Subgroup III−B by (Z)-β-ocimene and (E)-β-ocimene. The observed qualitative and quantitative chemical variability was probably due to combined factors, mostly phenology and season, then harvest site to a lesser extent. The lipoxygenase inhibition by a leaf oil sample was also evaluated. The oil IC50 (0.020 ± 0.005 mg/mL) was slightly higher than the non-competitive lipoxygenase inhibitor NDGA IC50 (0.013 ± 0.003 mg/mL), suggesting a significant in vitro anti-inflammatory potential. 相似文献
1000.