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排序方式: 共有347条查询结果,搜索用时 15 毫秒
291.
Dr. Xiaojing Wang Skye Shepherd Dr. Nantao Li Dr. Congnyu Che Dr. Tingjie Song Yanyu Xiong Isabella Rose Palm Dr. Bin Zhao Dr. Manish Kohli Prof. Utkan Demirci Prof. Yi Lu Prof. Brian T. Cunningham 《Angewandte Chemie (International ed. in English)》2023,62(16):e202217932
Exosomal microRNAs (miRNAs) have considerable potential as pivotal biomarkers to monitor cancer development, dis-ease progression, treatment effects and prognosis. Here, we report an efficient target recycling amplification process (TRAP) for the digital detection of miRNAs using photonic resonator absorption microscopy. We achieve multiplex digital detection with sub-attomolar sensitivity in 20 minutes, robust selectivity for single nucleotide variants, and a broad dynamic range from 1 aM to 1 pM. Compared with traditional qRT-PCR, TRAP showed similar accuracy in profiling exosomal miRNAs derived from cancer cells, but also exhibited at least 31-fold and 61-fold enhancement in the limits of miRNA-375 and miRNA-21 detection, respectively. The TRAP approach is ideal for exosomal or circulating miRNA biomarker quantification, where the miRNAs are present in low concentrations or sample volume, with potentials for frequent, low-cost, and minimally invasive point-of-care testing. 相似文献
292.
Dillon KB Goeta AE Howard JA Monks PK Shepherd HJ Thompson AL 《Dalton transactions (Cambridge, England : 2003)》2008,(9):1144-1149
Direct alkylation of cyclic triphosphenium ions by triflates to give di-ium dications is only possible for small organic substituents on the attacking reagent. The dicationic products are not intrinsically unstable, however, and in many instances they may be synthesised by an alternative route, pioneered by Schmidpeter and co-workers. These species may be readily identified in solution by (31)P NMR spectroscopy. The crystal and molecular structures of five such derivatives have been ascertained for the first time by single crystal X-ray diffraction at 120 K. The results confirm that normal single P-P bond lengths are present in the dications, in contrast with the monocationic parent cyclic triphosphenium ions, where structural determinations have shown that the P-P bond lengths are intermediate between single and double bonds. 相似文献
293.
A. Mancic J. Robiche P. Antici P. Audebert C. Blancard P. Combis F. Dorchies G. Faussurier S. Fourmaux M. Harmand R. Kodama L. Lancia S. Mazevet M. Nakatsutsumi O. Peyrusse V. Recoules P. Renaudin R. Shepherd J. Fuchs 《High Energy Density Physics》2010,6(1):21-28
A study of isochoric heating of Al foil by laser-accelerated proton beam is presented, coupling self-consistent hydrodynamic simulations (including proton stopping) with experimental measurements. The proton source that induces the heating has been characterized experimentally and the induced heating has been inferred through critical density expansion velocity measurement. The low-energy part of the proton spectrum that plays the dominant part in the heating process has been studied in detail. The experimental results are compared with the results of 1-dimensional hydrodynamic simulations that use as input the measured proton source and good agreement between the two is found using the SESAME EOS. 相似文献
294.
Film blowing is a highly complex industrial process used to manufacture thin sheets of polymer. Models that describe this process are highly nonlinear and numerical instabilities often occur when solving the highly nonlinear differential equations. This paper investigates the structure of typical solutions that arise when the polymer is assumed to be described by a power-law fluid operating under nonisothermal conditions. We consider both a shear-thinning and shear-thickening polymer and use a balance of orders argument to identify the structure of a region of rapid expansion in the radial profile of the film. A mixture of heuristic and singular perturbation techniques is applied to obtain a closed form approximate expression for the radial profile of the film which displays the interior layer phenomenon. We demonstrate how approximate solutions to the highly nonlinear two-point boundary value problem describing this process may be constructed using this expression as an initial estimate in an iterative scheme. Numerical solutions for the radial temperature, velocity and thickness profiles of the film are subsequently obtained by iteration. 相似文献
295.
M. Shepherd E. R. Weaver P. G. Ledig Aktiebolaget Carba K. Melanby H. L. Harden P. Borinski H. Murschhauser R. Staufer R. Krais H. Markert H. Mogilnickij H. Heinicke K. Heimberger L. C. Mc Nair H. C. Gull St. Hediger E. Lieber R. Rosen K. M. Watson N. H. Ceaglske 《Analytical and bioanalytical chemistry》1933,94(1-2):34-42
296.
297.
S. Coronel R. Mével S.P.M. Bane J.E. Shepherd 《Proceedings of the Combustion Institute》2013,34(1):895-902
Ignition energies for short duration (<50 ns) spark discharges were measured for undiluted and nitrogen-diluted H2-N2O mixtures of equivalence ratios ? = 0.15 and 0.2, dilution of 0% and 20% N2, and initial pressures of 15–25 kPa. The ignition events were analyzed using statistical tools and the probability of ignition versus spark energy density (spark energy divided by the spark length) was obtained. The simple cylindrical ignition kernel model was compared against the results from the present study. Initial pressure has a significant effect on the width of the probability distribution, ranging from a broad (P = 15 kPa) to a narrow (P = 25 kPa) probability distribution indicating that the statistical variation of median spark energy density increases as initial pressure of the mixture decreases. A change in the equivalence ratio from 0.15 to 0.2 had a small effect on the median spark energy density. The addition of 20% N2 dilution caused a significant increase in the median spark energy density when compared to no dilution. The extrapolation of the present results to atmospheric pressure, stoichiometric H2-N2O indicates that the electrostatic discharge ignition hazards are comparable to or greater than H2-O2 mixtures. 相似文献
298.
Shepherd RF Conrad JC Rhodes SK Link DR Marquez M Weitz DA Lewis JA 《Langmuir : the ACS journal of surfaces and colloids》2006,22(21):8618-8622
The microfluidic assembly of colloid-filled hydrogel granules of varying shape and composition is described. First, drops are formed by shearing a concentrated colloidal microsphere-acrylamide suspension in a continuous oil phase using a sheath-flow device. Both homogeneous and Janus (hemispherically distinct) spheres and disks are produced by confining the assembled drops in microchannels of varying geometry. Next, photopolymerization is carried out shortly after drop breakup to preserve their morphology. Representative wet and dried granules are characterized using fluorescence and scanning electron microscopy, respectively. Our approach offers a facile route for assembling colloid-filled hydrogel granules with controlled shape and composition. 相似文献
299.
The classic problem for a logistically evolving single species population being harvested involves three parameters: rate constant, carrying capacity and harvesting rate, which are taken to be positive constants. However, in real world situations, these parameters may vary with time. This paper considers the situation where these vary on a time scale much longer than that intrinsic to the population evolution itself. Application of a multiple time scale approach gives approximate explicit closed form expressions for the changing population, that compare favorably with those generated from numerical solutions. 相似文献
300.
Elastic low-energy electron diffraction intensity data have been measured as a function of energy for two directions of incidence for the (100) surface of rhodium. The dynamical perturbation programs of Van Hove and Tong have been used for analysing these new experimental data, and it is concluded that the normal face-centered cubic registry is maintained to the surface layer. A preliminary comparison between measured and calculated I(E) curves indicates the topmost interlayer spacing to be 1.96 ± 0.10 Å, and therefore possibly slightly expanded from the bulk interlayer spacing of 1.90 Å. 相似文献