排序方式: 共有47条查询结果,搜索用时 15 毫秒
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The technique of ferromagnetic resonance at 23 GHz has been used to determine the first three anisotropy constants of pure Ni down to 4.2K. A temperature and orientation dependent linewidth has also been observed. 相似文献
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Adamson P Auty DJ Ayres DS Backhouse C Barr G Barrett WL Bishai M Blake A Bock GJ Boehnlein DJ Bogert D Bower C Budd S Cavanaugh S Cherdack D Childress S Choudhary BC Coelho JA Cobb JH Coleman SJ Corwin L Cravens JP Cronin-Hennessy D Danko IZ de Jong JK Devenish NE Diwan MV Dorman M Escobar CO Evans JJ Falk E Feldman GJ Frohne MV Gallagher HR Gomes RA Goodman MC Gouffon P Gran R Grant N Grzelak K Habig A Harris D Harris PG Hartnell J Hatcher R Himmel A Holin A Huang X Hylen J Ilic J Irwin GM 《Physical review letters》2010,105(15):151601
We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be a consequence of Lorentz and CPT violation as described by the standard-model extension framework. It also would be the first detection of a perturbative effect to conventional neutrino mass oscillations. We found no evidence for this sidereal signature, and the upper limits placed on the magnitudes of the Lorentz and CPT violating coefficients describing the theory are an improvement by factors of 20-510 over the current best limits found by using the MINOS near detector. 相似文献
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T Footz S Wunsam S Kulak H J Crabtree D M Glerum C J Backhouse 《Electrophoresis》2001,22(18):3868-3875
Sample preparation has long been recognized as a significant barrier to the implementation of macroscopic protocols on microfabricated devices. Macroscopically, such tasks as removing salts, primers and other contaminants are performed by methods involving precipitation, specialized membranes and centrifuges, none of which are readily performed in microfluidic structures. Although some microfluidic systems have been developed for performing sample purification, their complexity may hinder the degree to which they can be implemented. We present a method of microchip-based sample purification that can be performed with even the simplest microfluidic designs. The technique is demonstrated by removing primers from a sample of amplified DNA, leaving only the product DNA. This provides a new sample preparation capability for microfluidic systems. 相似文献
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Oliver J. Backhouse Dr. Joseph C. R. Thacker Prof. Paul L. A. Popelier 《Chemphyschem》2019,20(4):555-564
The energy profiles of hydrogen-bonded heterocyclic aromatics have been decomposed into atomistic energy contributions using the Interacting Quantum Atoms (IQA) method. The resulting energy contributions have been sequenced by the Relative Energy Gradient (REG) approach to determine their influence upon the shape of these energy profiles. The results show inadequacies in Jorgensen's secondary interaction hypothesis (SIH). A novel method of finding a condensed analogy for the interaction between the molecules is presented. The findings of this work further doubt the validity of the SIH, and reinforce previous warnings against its misguided use. 相似文献
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As microfluidic chips come to integrate the higher levels of functionality required for the implementation of advanced bioanalytical protocols, a crucial factor is that of cost. Although glass chips provide advantages in multilayer integrations, their cost is far higher than that of polymer chips. However, a simple and effective rejuvenation protocol for glass microchips may enable higher levels of integration and functionality on glass microchips. Here we present a method to rejuvenate glass microchips that had been used for capillary electrophoresis to the extent that their performance was degraded. This degradation was due to one of the two mechanisms: (i) a deterioration of the polymer coating on the inner surface of the microchannel or (ii) an aging of the glass substrate. Using the method presented here, we have rejuvenated more than 50 such "aged" microchips. The performance of these microchips was fully restored after the rejuvenation and lasted for hundreds of DNA separation runs. Our experiments indicate that the loss of resolution in microchip separations was not associated with glass aging, but was due to the degradation of the polymer coating on the inner surface of microchannels. This suggests that it is possible to extend the microchip lifetime "forever" using the rejuvenation protocol and that the exploration of higher levels of integration and functionality on glass microchips (or of hybrid structures involving materials capable of withstanding the reagents and elevated temperatures used) is feasible. 相似文献
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An integrated CMOS high voltage supply for lab-on-a-chip systems 总被引:1,自引:0,他引:1
Behnam M Kaigala GV Khorasani M Marshall P Backhouse CJ Elliott DG 《Lab on a chip》2008,8(9):1524-1529
Electrophoresis is a mainstay of lab-on-a-chip (LOC) implementations of molecular biology procedures and is the basis of many medical diagnostics. High voltage (HV) power supplies are necessary in electrophoresis instruments and are a significant part of the overall system cost. This cost of instrumentation is a significant impediment to making LOC technologies more widely available. We believe one approach to overcoming this problem is to use microelectronic technology (complementary metal-oxide semiconductor, CMOS) to generate and control the HV. We present a CMOS-based chip (3 mm x 2.9 mm) that generates high voltages (hundreds of volts), switches HV outputs, and is powered by a 5 V input supply (total power of 28 mW) while being controlled using a standard computer serial interface. Microchip electrophoresis with laser induced fluorescence (LIF) detection is implemented using this HV CMOS chip. With the other advancements made in the LOC community (e.g. micro-fluidic and optical devices), these CMOS chips may ultimately enable 'true' LOC solutions where essentially all the microfluidics, photonics and electronics are on a single chip. 相似文献
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We demonstrate the fabrication and characterization of a novel, inexpensive microchip capable of laser induced fluorescence (LIF) detection using integrated waveguides with built-in optical filters. Integrated wavelength-selective optical waveguides are fabricated by doping poly(dimethysiloxane) (PDMS) with dye molecules. Liquid-core waveguides are created within dye-doped PDMS microfluidic chips by filling channels with high refractive index liquids. Dye molecules are allowed to diffuse into the liquid core from the surrounding dye-doped PDMS. The amount of diffusion is controlled by choosing either polar (low diffusion) or apolar (high diffusion) liquid waveguide cores. The doping dye is chosen to absorb excitation light and to transmit fluorescence emitted by the sample under test. After 24 h, apolar waveguides demonstrate propagation losses of 120 dB cm(-1) (532 nm) and 4.4 dB cm(-1) (633 nm) while polar waveguides experience losses of 8.2 dB cm(-1) (532 nm) and 1.1 dB cm(-1) (633 nm) where 532 and 633 nm light represent the excitation and fluorescence wavelengths, respectively. We demonstrate the separation and detection of end-labelled DNA fragments using polar waveguides for excitation light delivery and apolar waveguides for fluorescence collection. We demonstrate that the dye-doped waveguides can provide performance comparable to a commercial dielectric filter; however, for the present choice of dye, their ultimate performance is limited by autofluorescence from the dye. Through the detection of a BK virus polymerase chain reaction (PCR) product, we demonstrate that the dye-doped PDMS system is an order of magnitude more sensitive than a similar undoped system (SNR: 138 vs. 9) without the use of any external optical filters at the detector. 相似文献
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