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-Polymerase Chain Reaction (PCR) technology has been widely used in molecular biology, forensic analysis, evolutionary and medical diagnostic. PCR requirement for point of care application is shorten reaction time and reduces PCR reagent. If the PCR chip can be done by droplet basis, then the analysis system which minimal amount of fluid will be possible. In this report, we describe the simulation and experimental study of a parallel-plate electrowetting on dielectric (EWOD) based PCR device. The EWOD device is applied to control PCR reagent and sample for a polymerase chain reaction (PCR) system. The EWOD-based PCR system consists of 3.4 mm wide, 15.1 mm long serpentine-shape microheater integrated underneath to maintain temperature at each stage and 370 μm deep microchannel. DNA was driven by moving droplet through each square electrode (dimension 1x1 mm 2 ) that maintains temperature at denaturation, annealing, and extension region. The fluid dynamics of the device have been modeled by Coventorware , a commercially available MEMS simulation software, to show temperature distribution on each electrode. In experiment, this work studied contact angle reduction of different droplet because this result can be studied possibility of transporting of PCR reagent for a droplet based PCR.

Recently, we have demonstrated that DNA hybridization using acoustic streaming induced by two piezoelectric transducers provides higher DNA hybridization efficiency than the conventional method. In this work, we refine acoustic streaming system for DNA hybridization by inserting an additional piezoelectric transducer and redesigning the locations of the transducers. The Comsol® Multiphysics was used to design and simulate the velocity field generated by the piezoelectric agitation. The simulated velocity vector followed a spiral vortex flow field with an average direction outward from the center of the transducers. These vortices caused the lower signal intensity in the middle of the microarray for the two-piezoelectric disk design. On the contrary, the problem almost disappeared in the three-piezoelectric-disk system. The optimum condition for controlling the piezoelectric was obtained from the dye experiments with different activation settings for the transducers. The best setting was to activate the side disks and middle disk alternatively with 1 second activating time and 3 second non-activating time for both sets of transducers. DNA hybridization using microarrays for the malaria parasite Plasmodium falciparum from the optimized process yielded a three-fold enhancement of the signal compared to the conventional method. Moreover, a greater number of spots passed quality control in the optimized device, which could greatly improve biological interpretation of DNA hybridization data.

Higher OH concentration is identified in tetragonal barium titanate (BaTiO) nanorods synthesized by a hydrothermal method with a 10 vol % ethylene glycol solvent (Inada, M.; et al. Ceram. Int. 2015, 41, 5581-5587). This is apparently inconsistent with the known fact that higher OH concentration in the conventional hydrothermal synthesis makes pseudocubic BaTiO nanocrystals more stable than the tetragonal one. To understand where and how the introduced OH anions are located and behave in the nanocrystals, we applied ab initio analysis to several possible microscopic geometries of OH locations, confirming the relative stability of the tetragonal distortion over the pseudocubic one because of the preference of trans-type configurations of OH anions. We also performed Fourier transform infrared and X-ray diffraction analysis, all being consistent with the microscopic picture established by the ab initio geometrical optimizations.

The ability for low reagent consumption and minimum waste production in a miniaturised system has generated great interest in the green chemistry field. Herein, a microfluidic system for calcium assays using the arsenazo III method has been developed. The reaction between arsenazo III and calcium to form a blue-purple coloured complex is measured by an embedded miniature fibre optic spectrometer through absorbance increments at 650 nm. A linear range was obtained from 0.2 to 3 mg dL -1 with a detection limit of 0.138 mg dL -1 (S/N=3). The method exhibited good reproducibility based on low and high calcium tests with control serums, the within-run coefficient of variation (CVs) (4.10% and 3.91%), and the run-to-run CV (4.6%) were obtained. The carry-over effect of the method was also 1.98%, which is acceptable for the current system. When compared to a conventional spectrophotometric method, this portable, microfluidic method correlated highly when evaluating serum samples (r 2 =0.985; n=15). This similarity suggests that our proposed system could be used for determining the amount of calcium in serum samples.

Volatile fatty acids of acetic, butyric, lactic, and propionic acids play an important role in the methane fermentation process. Particularly significant amount of propionic acid presence in the process will influence the methane fermentation efficiency. Herein, zigzag‐aligned silver nanorods were designed as surface‐enhanced Raman scattering (SERS)‐active substrates to establish the classification of volatile fatty acids against the traditional poor sensitive and time‐consuming titration and gas chromatography methods. SERS and chemometric method of principal component analysis is used for the detection and classification of volatile fatty acids. Density functional theory calculations were performed to understand the Raman vibrations and compare with experimental observations and to aid in the assignments of spectral lines. For the first time, the authors have used SERS technique to classify the acids. The findings suggest that this method is of great potential in the field of methane fermentation from industrial waste.

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