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971.
J. Arvieux J. Ball J. Bystricky J. M. Fontaine G. Gaillard J. P. Goudour R. Hess R. Kunne F. Lehar A. de Lesquen D. Lopiano M. de Mali F. Perrot-Kunne D. Rapin L. van Rossum J. L. Sans H. M. Spinka 《Zeitschrift fur Physik C Particles and Fields》1997,76(3):465-468
We analyze the possibility of testing local Lorentz invariance from the observation of tau decays. Future prospects of probing distances below the electroweak characteristic scale are discussed. 相似文献
972.
M. P. Sulbaek Andersen M. D. Hurley J. C. Ball W. F. Schneider T. J. Wallington O. J. Nielsen 《国际化学动力学杂志》2003,35(4):159-165
The synthesis, IR spectrum, and first‐principles characterization of CF3CH(ONO)CF3 as well as its use as an OH radical source in kinetic and mechanistic studies are reported. CF3CH(ONO)CF3 exists in two conformers corresponding to rotation about the RCO? NO bond. The more prevalent trans conformer accounts for the prominent IR absorption features at frequencies (cm?1) of 1766 (N?O stretch), 1302, 1210, and 1119 (C? F stretches), and 761 (O? N? O bend); the cis conformer contributes a number of distinct weaker features. CF3CH(ONO)CF3 was readily photolyzed using fluorescent blacklamps to generate CF3C(O)CF3 and, by implication, OH radicals in 100% yield. CF3CH(ONO)CF3 photolysis is a convenient source of OH radicals in the studies of the yields of CO, CO2, HCHO, and HC(O)OH products which can be difficult to measure using more conventional OH radical sources (e.g., CH3ONO photolysis). CF3CH(ONO)CF3 photolysis was used to measure k(OH + C2H4)/k(OH + C3H6) = 0.29 ± 0.01 and to establish upper limits of 16 and 6% for the molar yields of CO and HC(O)OH from the reaction of OH radicals with benzene in 700 Torr of air at 296 K. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 159–165, 2003 相似文献
973.
N Prasad S C Bushong J I Thornby R N Bryan C F Hazlewood J E Harrell 《Magnetic resonance imaging》1984,2(1):37-39
Three groups of six male Balb/c mice, subjected to 30 MHz continuous wave NMR exposure in a static magnetic field of 7.05 K Gauss for one hour, were each compared to another group of ten unexposed mice with respect to chromatid and chromosomal aberrations. The exposed groups were sacrificed at two hours, 24 hours and 48 hours following NMR exposure respectively. Control mice were sacrificed 24 hours after sham-exposure. All groups had approximately 0.02 apparent aberrations per cell. These apparent aberrations were in the form of metacentric chromosomes, possibly resulting from a union of chromosomes at their centromeres or possibly simply chromosomes in association. The results are consistent with earlier in vitro findings that NMR exposure causes no adverse cytogenetic effects. 相似文献
974.
Chang BH Gujral TS Karp ES BuKhalid R Grantcharova VP MacBeath G 《Chemistry & biology》2011,18(9):1143-1152
PDZ domains are independently folded modules that typically mediate protein-protein interactions by binding to the C termini of their target proteins. However, in a few instances, PDZ domains have been reported to dimerize with other PDZ domains. To investigate this noncanonical-binding mode further, we used protein microarrays comprising virtually every mouse PDZ domain to systematically query all possible PDZ-PDZ pairs. We then used fluorescence polarization to retest and quantify interactions and coaffinity purification to test biophysically validated interactions in the context of their full-length proteins. Overall, we discovered 37 PDZ-PDZ interactions involving 46 PDZ domains (~30% of all PDZ domains tested), revealing that dimerization is a more frequently used binding mode than was previously appreciated. This suggests that many PDZ domains evolved to form multiprotein complexes by simultaneously interacting with more than one ligand. 相似文献
975.
Thompson MG White MR Linford BD King KA Robinson MM Parnis JM 《Journal of mass spectrometry : JMS》2011,46(10):1071-1078
The products of the Ar?+ charge exchange ionization of acetaldehyde have been isolated and compared with related photoionization results and computational work. Acetaldehyde has been used to assess the effect of varied ion density in the ionization region of the electron bombardment matrix isolation apparatus. The amount of acetaldehyde destruction has been measured for constant gas‐sample composition and constant ionization current for two anode geometries: a pin anode and a plate anode. For the same ionization current, a pin‐shaped anode demonstrates higher precursor molecule destruction efficiency (85%) than the plate‐shaped anode (30%), resulting in substantial effect on the yield and quantity of isolated products. When the plate anode is used, the observed infrared products correspond to matrix‐isolated carbon monoxide (CO), methane (CH4), ketene (CH2CO), ethynyloxy radical (HCCO), formyl radical (HCO?), acetyl radical (CH3CO?), vinyl alcohol (H2C = CH‐OH), and cationic proton‐bound dimer, Ar2H+. When the pin anode is used, the same products are observed with different relative proportions and new absorption features corresponding to dicarbon monoxide (CCO) and methyl radical (CH3?) are observed. The surprising observation of infrared absorptions corresponding to vinyl alcohol along with low yield of products anticipated through the analysis of photoelectron–photoionization coincidence measurements suggests that the initially formed fragmentation products are able to further react within the matrix‐isolation environment to influence observed product yields. Related experiments, using the isotopomer CD3CHO, suggest that the observed products are formed via radical–radical reactions that occur under the high pressure conditions of the matrix isolation environment. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
976.
Bae WJ Davis AR Jung J Jo WH Carter KR Coughlin EB 《Chemical communications (Cambridge, England)》2011,47(38):10710-10712
A simple self-catalyzed hydroamination method for creating hybrid TiO(2)-polyaniline core-shell nanoparticles (NP) has been shown. Hybrid NPs with a range of possible sizes are afforded in high yield under mild reaction conditions and simultaneously show improved charge transport and electrochromic behavior compared to either polyaniline alone or physically blended with TiO(2). 相似文献
977.
Carlson B Aquino AJ Hope-Weeks LJ Whittlesey B McNerney B Hase WL Krempner C 《Chemical communications (Cambridge, England)》2011,47(39):11089-11091
The first zwitterionic alkaline earth metal silanides featuring two naked silyl anions were synthesized and a combined structural and computational study on these zwitterions revealed a correlation between the energy of the HOMO and the degree of negative charge of the naked silyl anions. 相似文献
978.
Smith BA Daschbach MM Gammon ST Xiao S Chapman SE Hudson C Suckow M Piwnica-Worms D Gokel GW Leevy WM 《Chemical communications (Cambridge, England)》2011,47(28):7977-7979
Synthetic ion channel hydraphiles, which are known to infiltrate membranes and disrupt ion homeostasis, were tested as direct injection toxins in live mice as potential schlerotic agents. The study uses a near-IR dye to image and evaluate the success of the approach. 相似文献
979.
Meltzer RH Krogmeier JR Kwok LW Allen R Crane B Griffis JW Knaian L Kojanian N Malkin G Nahas MK Papkov V Shaikh S Vyavahare K Zhong Q Zhou Y Larson JW Gilmanshin R 《Lab on a chip》2011,11(5):863-873
Rapid, specific, and sensitive detection of airborne bacteria, viruses, and toxins is critical for biodefense, yet the diverse nature of the threats poses a challenge for integrated surveillance, as each class of pathogens typically requires different detection strategies. Here, we present a laboratory-on-a-chip microfluidic device (LOC-DLA) that integrates two unique assays for the detection of airborne pathogens: direct linear analysis (DLA) with unsurpassed specificity for bacterial threats and Digital DNA for toxins and viruses. The LOC-DLA device also prepares samples for analysis, incorporating upstream functions for concentrating and fractionating DNA. Both DLA and Digital DNA assays are single molecule detection technologies, therefore the assay sensitivities depend on the throughput of individual molecules. The microfluidic device and its accompanying operation protocols have been heavily optimized to maximize throughput and minimize the loss of analyzable DNA. We present here the design and operation of the LOC-DLA device, demonstrate multiplex detection of rare bacterial targets in the presence of 100-fold excess complex bacterial mixture, and demonstrate detection of picogram quantities of botulinum toxoid. 相似文献
980.
This communication describes the first observation and study of C-H activation at a Pd(IV) center. This transformation was achieved by designing model complexes in which the rate of reductive elimination is slowed relative to that of the desired C-H activation process. Remarkably, the C-H activation reaction can proceed under mild conditions and with complementary site selectivity to analogous transformations at Pd(II). These results provide a platform for incorporating this new reaction as a step in catalytic processes. 相似文献