The separation of the homoduplex and heteroduplex PCR products was explored by using the chip-based temperature gradient electrophoresis. A two-dimensional electrophoresis chip incorporated with the temperature gradient feature was designed to increase the throughput and further enhance the separation efficiency.
Abstract Recent experiments have demonstrated that a high separatrix density and a large ratio of separatrix density to pedestal top density are two crucial conditions for achieving high confinement operation with small edge localized modes (ELMs). In order to identify the underlying physics of this phenomenon, a series of equilibria with different separatrix and pedestal top densities are constructed, and their peeling–ballooning (P–B) instabilities are analyzed through simulation. It is found that there is a threshold value of pedestal top density which comes from competition between ion inertia and diamagnetic effect, and ELM energy loss can be minimized at the threshold value for a fixed separatrix density. When the pedestal top density is smaller than the threshold value, the ion inertial effect induced by the density profile has a significant influence on the growth of ELMs, resulting in an increased linear growth rate and more ELM energy loss by trigging low -n modes ( n being the toroidal mode number) in the nonlinear phase. When the pedestal top density is larger than the threshold value, the diamagnetic effect is the main factor determining the mode spectrum, which moves to the high -n region with a larger growth rate and the nonlinear ELM energy loss increases. However, for a fixed pedestal top density, a larger separatrix density leads to a wider mode spectrum with a smaller growth rate; thus ELM energy loss is reduced. The results of this research provide a new mechanism, namely that the P–B mode is possibly transferred to a resistive ballooning mode, to interpret the experimental findings during high pedestal density operation.
Abstract The effects of resonant magnetic perturbation (RMP) fields on peeling–ballooning (P–B) modes are studied with the experimental equilibria of EAST based on the four-field model in BOUT++ code. As the two basic types of plasma responses, the magnetic and the transport response to RMP are considered in our simulation to reveal the roles of the plasma response during edge localized mode mitigation. On the one hand, the results show that RMP can reduce the linear growth rates of the P–B modes and the pedestal energy loss in the nonlinear process by directly coupling with the P–B modes. The magnetic response can weaken the impacts of RMPs on the P–B modes by partially screening the applied RMP fields more precisely the resonant components. On the other hand, RMP can further reduce the linear growth rates of the P–B modes and the pedestal energy loss by changing the equilibrium pressure profiles through the transport response. More detailed analysis suggests that, compared with other resonant components of RMPs, the components whose corresponding rational surfaces are located at the top of the pedestal can lead to stronger reductions in the linear growth rates of the P–B modes, and can reduce pedestal energy loss more significantly by enhancing multi-mode coupling in the nonlinear process. Finally, the multi-mode coupling increases with the strength of the resonant components, so one can change the RMP poloidal spectrum by adjusting the phase difference Δϕ between the upper and low RMP coils from 0 to 360∘ , and hence obtain the optimal coil phase difference that leads to the strongest reductions in the linear growth rates of the P–B modes and the pedestal energy loss through maximizing the strength of resonant components, especially the resonant components whose corresponding rational surfaces are located at the top of the pedestal.
Stimulus-frequency otoacoustic emissions (SFOAEs) can be useful tools for assessing cochlear function noninvasively. However, there is a lack of reports describing their utility in predicting hearing capabilities. Data for model training were collected from 245 and 839 ears with normal hearing and sensorineural hearing loss, respectively. Based on SFOAEs, this study developed an objective assessment system consisting of three mutually independent modules, with the routine test module and the fast test module used for threshold prediction and the hearing screening module for identifying hearing loss. Results evaluated via cross-validation show that the routine test module and the fast test module predict hearing thresholds with similar performance from 0.5 to 8 kHz, with mean absolute errors of 7.06–11.61 dB for the routine module and of 7.40–12.60 dB for the fast module. However, the fast module involves less test time than is needed in the routine module. The hearing screening module identifies hearing status with a large area under the receiver operating characteristic curve (0.912–0.985), high accuracy (88.4–95.9%), and low false negative rate (2.9–7.0%) at 0.5–8 kHz. The three modules are further validated on unknown data, and the results are similar to those obtained through cross-validation, indicating these modules can be well generalized to new data. Both the routine module and fast module are potential tools for predicting hearing thresholds. However, their prediction performance in ears with hearing loss requires further improvement to facilitate their clinical utility. The hearing screening module shows promise as a clinical tool for identifying hearing loss.
Abstract Recently, the analysis of single-nucleotide polymorphisms (SNPs) has attracted much attention. Although many techniques have been reported, new methods with high resolving power, low-cost, and fast speed are still required to meet the great demand of analyzing and detecting large amount of SNPs in the human genome. Capillary electrophoresis (CE) in the microchip format is a powerful separation technique, and has been applied to many fields in recent years, including SNPs detection. In this work, we present a fast SNPs detection scheme based on chip-based temperature gradient capillary electrophoresis. The cross-channel CE chip is made of poly- (dimethylsiloxane) (PDMS). A temporal temperature gradient with a precision of 0.1°C per step was applied on the chip during the separation process. The Cy5-labeled PCR products which contain one and two SNP sites were separated and detected. The homoduplexes and heteroduplexes were successfully base-line resolved and the total time of a single run was only 8 min. The separation was also confirmed by DHPLC. This work indicates that chip-based temperature gradient capillary electrophoresis is a fast and convenient screening approach for recognizing the presence of SNPs prior to further characterization. This method can be used for detecting both known and unknown mutations.
A multiplex asymmetric PCR (MAPCR)-based microarray method was developed for the detection of 10 known extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC beta-lactamase genes in gram-negative bacteria and for the typing of six important point mutations (amino acid positions 35, 43, 130, 179, 238, and 240) in the bla(SHV) gene. The MAPCR is based on a two-round reaction to promote the accumulation of the single-stranded amplicons amenable for microarray hybridization by employing multiple universal unrelated sequence-tagged primers and elevating the annealing temperature at the second round of amplification. A strategy to improve the discrimination efficiency of the microarray was constituted by introducing an artificial mismatch into some of the allele-specific oligonucleotide probes. The microarray assay correctly identified the resistance genes in both the reference strains and some 111 clinical isolates, and these results were also confirmed for some isolates by direct DNA sequence analysis. The resistance genotypes determined by the microarray correlated closely with phenotypic MIC susceptibility testing. This fast MAPCR-based microarray method should prove useful for undertaking important epidemiological studies concerning ESBLs and plasmid-mediated AmpC enzymes and could also prove invaluable as a preliminary screen to supplement phenotypic testing for clinical diagnostics.
Aiming at the complicated surface structure of coal,atomic force microscopy(AFM) is used to observe surface characteristic of coal in mesoscopic scale.A preliminary observation on the surface of coal is done by AFM.The two-dimension and three-dimension graphics are obtained.The analysis of the roughness,hierarchic and power on coal surface is concluded according to AFM observation.The result indicates that amplitude parameters are characteristic parameters that are token surface roughness and it is useful to analyse the surface fractal character by using power spectrum.It is obvious that it may be as a new method for coal surface in mesoscopic scale that AFM is used in studying of coal surface.
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