An integrated genetic analysis microfluidic platform with valves and a PCR chip reusability method to avoid contamination

Clinical diagnostics and genomic research often require performing numerous genetic tests. While microfluidic devices provide a low-cost alternative to such demands, integrated microfluidic devices are fabricated using expensive technology not always affordable for single use. However, carryover cross-contamination (CXC) concerns (i.e. either false positive or false negative PCR data) in PCR chips prevent reuse, defying much of the advantages of miniaturized systems developed using expensive MEMS processing. In this work, we present an integrated and reusable PCR–CE glass microfluidic chip capable of multi-chamber PCR and sequential CE, with emphasis on a unique chip reusability approach to avoid CXC. For reliable PCR, the surface of the chamber is re-configured from its virgin hydrophilic (CA < 20°) to hydrophobic (CA > 110°) by silanization. To then extend this silanization method as a chip reusability technique, the silanization coating is ‘stripped and re-silanized’ (SRS) to create a fresh coating prior to each successive PCR run. Experimental confirmation of the effectiveness of SRS method in avoiding the CXC is demonstrated using plasmid DNA and HIV-1 infected DNA samples. We also present passive plug microvalves incorporated in the chip to enable fluid/vapor retention during the PCR and controlled fluid flow from the PCR chamber to the CE section for further analysis.     

Preferential grain growth and improved fatigue endurance in Sr substituted PZT thin films on Pt(1 1 1)/TiOx/SiO2/Si substrates

Pb(Zr_0.5Ti_0.5)O₃ and (Pb_0.9Sr_0.1)(Zr_0.5Ti_0.5)O₃ thin films were grown on Pt/TiO_x/SiO₂/Si substrates by chemical solution deposition. 10% Sr substituted PZT film showed high degree of (0 0 1) type preferential grain growth. Surface morphology revealed a clear correlation between preferred grain orientation and grain size. Room temperature dielectric constant was 1200 and 700 for the PZT and PSZT films, respectively. Dielectric loss reduced with Sr substitution. PZT film showed severe fatigue, and hence the polarization reduced to 20% of the initial value (24 μC/cm²) after 10⁸ cycles where as PSZT showed less fatigue, 75% of the initial polarization (12 μC/cm²) was retained after 10⁸ switching cycles.     

Carbon nanohorn‐graphene nanoplate hybrid: An excellent electrode material for supercapacitor application

This study describes the capacitor behavior of carbon nanohorn (CNH)/graphene nanoplate (GNP) hybrid (CNGN). The well‐CNH‐decorated GNP‐plate electrode materials show high capacitance value (≈677 F/g) and can be extensively used in new generation for energy storage. In the hybrid (CNGN), two nanofillers jointly affect the capacitance behavior and increase the capacitance value of the CNGN hybrid. Homogeneous coating of CNH over the GNP plate plays an effective role to enhance the capacitance behavior of the composite. Field emission scanning electron microscopy and high‐resolution transmission electron microscopy analysis of the composite confirmed the CNH coating on the GNP plate. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42118.     

Thermal Decomposition Of Carbonyl Sulfide At Temperatures Encountered In The Front End Of Modified Claus Plants

Understanding the kinetics of the formation and consumption of COS and CS₂ in the front end of the modified Claus process will be a significant step towards reducing the environmental impact of these plants. Specifically, homogeneous intrinsic rate expressions are needed for engineering design and simulation, which will lead to new, optimized ways of operating these plants. Hence, a high-temperature kinetic study of the COS decomposition reaction was carried out. Experiments were performed with inlet COS compositions in the range of 0.20-2.33 mol%, with pressures at 101-150 kPa and temperatures at 800-1100°C; these conditions cover the conditions typically encountered in the front end of the modified Claus process. The experimental results showed that COS conversion is dependent on the inlet concentration of COS, which contrasts with previously reported higher temperature studies. Finally, the COS decomposition kinetics were modeled as the sum of two reactions, which provided a satisfactory representation of experimental data.     

Coupling of conductivity to the relaxation process in polymer electrolytes

Conductivity relaxation using modulus formalism has been used to explore the coupling of ionic conductivity to dielectric relaxation in polymer electrolyte based on polyethylene oxide complexed with various content of LiAsF₆. The temperature dependence of conductivity followed the VTF behavior suggesting close correlation between conductivity and the segmental relaxation process in polymer electrolytes. The coupling of conductivity to the segmental process has been discussed in terms of coupling index. For all compositions studied, the coupling index was within the range of 1–11 in the temperature range of investigation, which was in agreement with the coupled systems.     

An Adaptive Non Reference Anchor Array Framework for Audio Retrieval in Teleconferencing Environment

In this paper, an adaptive framework for audio retrieval in live teleconferencing environments with multiple participants is proposed. The framework uses a non reference anchor array (NRA) to capture the interfering speech sources, in addition to the primary array that captures the speech source of interest (SOI). A linearly constrained-minimum variance (LC-MV) beamformer is used herein such that the signal coming from the look direction is preserved while interferences coming from the non look direction are nulled. Additionally, the reverberant component of the speech acquired by this framework is removed by a novel method that uses the linear prediction (LP) residual cepstrum. This method does not require the computation of the acoustic impulse response (AIR) of the teleconferencing room and hence is computationally efficient. The NRA framework is therefore able to remove correlated noise coming from the direction of the SOI and also dereverberating the noise free signal. The performance of the proposed framework is evaluated by conducting experiments on clean speech acquisition from distant microphone arrays. Experiments on distant speech recognition are also conducted using the TIMIT and MONC databases. Experimental results obtained from the proposed framework indicate a reasonable improvement over correlation, subspace and standard minimum variance beamforming methods. The application of the framework in audio retrieval in a live teleconferencing environment with multiple participants is also discussed.     

Some estimators of finite population variance using information on two auxiliary variables

Some estimators using information on two auxiliary variables for finite population variance are proposed, their bias and mean square error (MSE) are found, and their properties are analysed. As an illustration, an empirical study is also included.     

On estimation of population mean using known coefficient of variation

For the estimation of population mean, a generalized class of estimators using known coefficient of variation C_y of the study variable y is proposed, its bias and mean square error (MSE) are found and its comparative study with the usual mean per unit estimator has been done. As an illustration, an empirical study is also included.     

Geometrically non-linear formulation for two dimensional curved beam elements

This paper presents a geometrically non-linear formulation using a total lagrangian approach for the two dimensional curved beam elements. The beam element is derived using linear, paralinear and cubic-linear plane stress elements. The basic element geometry is constructed using the coordinates of the nodes on the element center line (η = 0) and the nodal point normals. The element displacement field is described using two translations of the node on the center line and a rotation about the axes normal to the plane containing the center line of the element. The existing beam element formulations are restricted to small nodal rotations between two successive load increments. The element formulation presented here removes such a restriction. This is accomplished by retaining non-linear nodal rotation terms in the definition of the displacement field and the consistent derivation of the element properties. The formulation presented here is very general and yet can be made specific by selecting appropriate non-linear functions representing the effects of nodal rotations. The element properties are derived and presented in detail. Numerical examples are also presented to demonstrate the behavior and the accuracy of the two dimensional beam elements for geometrically non-linear applications. In all cases comparisons made with theory and/or other published data show that the beam elements product accurate results and permit large load increments with good convergence characteristics.