Concentration protile of etchant measured by microelectrode technique in the process of chemical micromachining

A carbon-disk microelectrode was used to investigate the surface concentration profile of etchant Br-2, which was electrogenerated on the Pt working electrode. The steady state reducing currents of Br-2 at different distances away from the Pt electode was measured. The concentration profile was estimated from the current-distance variation curves as a function of different sampling times. Experimentally determined concentration profiles are in good agreement with those estimated from the microetching results. The microelectrode technique has offered a good method to choose suitable etching solution for chemical micromachining

High-Transmittance Subwavelength Metal Grating with Relief Structure Composed of Multiple Steps

A new kind of subwavelength metal grating with relief structure is designed and analyzed, in which the shape of the grating lines is no longer a single rectangle, but a relief structure with multiple steps. GsolverV52 was used to determine the optimal values of the grating period, groove depth, and the number of steps. The optical performance of the novel structure is evaluated and compared in terms of the transmission efficiency and extinction ratio over the visible and near-infrared wavelength spectrum. It is shown that, in the near-infrared band, the maximum transmittance can be increased about 15% compared to the traditional metal grating under the same parameters. With the unique characteristics, the metal grating is expected to find applications in liquid crystal display fields, polarization imaging, optical communication, and so on

Three-dimensional electrochemical microfabrication of n-GaAs using L-cystine as a scavenger

The confined etchant layer technique (CELT) was used to fabricate complex three-dimensional (3D) microstructures on gallium arsenide (n-GaAs). The design of an appropriate chemical etching system is needed in order to realize successful microfabrication. In this study, Br-2 was electro-generated at the mold surface and used as an efficient etchant for n-GaAs. The use Of L-Cystine as a scavenger to replace the toxic scavenger H3AsO3 was explored. The resolution of the fabricated microstructure depended strongly on the composition of the electrolyte, and especially on the concentration ratio between L-cystine and KBr. A well-defined and polished Pt micro-cylindrical electrode with a diameter of similar to 50 mu m was employed as one kind of mold for CELT. By inspecting the deviation of the sizes of the etching spots from the real diameter of the microelectrode, the thickness of confined etchant layer (CEL) can be estimated and thus the composition of electrolyte can be optimized for better etching precision. By choosing an appropriate concentration ratio between L-cystine and KBr, complex microstructures were fabricated successfully on n-GaAs. The etched patterns on n-GaAs were approximately negative copies of the mold, and the precision of duplication could easily reach the submicrometer scale, which was better than that achieved with H3AsO3. The experimental results indicated that L-Cystine is a good scavenger for microfabrication on n-GaAs by CELT. This technique avoids severe pollution of the environment, which will help to extend its future application in industry. (c) 2006 Published by Elsevier Ltd

An enhanced equivalent circuit model of vanadium redox flow battery energy storage systems considering thermal effects

Thermal issue is one of the major concerns for safe, reliable, and efficient operation of the vanadium redox flow battery (VRB) energy storage systems. During the design of the operational strategy for a grid-connected VRB system, a suitable mathematical model is needed to predict the dynamic behaviors under various operating conditions. However, conventional VRB models usually neglect the impact of temperature variations on system performance. This work develops an enhanced VRB model with the consideration of the coupling effects between the electrochemical and the thermal behaviors. The proposed model consists of two equivalent circuits. First, the electrochemical behaviors of the VRB are modeled by a second-order RC network taking account of the effects of concentration variation of the vanadium ions and the electrochemical activation. Second, a third-order Cauer network is used to model the heat transfer process in the VRB system, and the dynamic thermal behaviors of stacks, pipes and heat exchangers are characterized. Well-designed experiments and particle swarm optimization algorithm are use to identify the parametric values of the developed model. The proposed modeling method was validated experimentally using a 5kW/3kWh VRB platform, and the results show that the model is capable of accurately predicting the VRB performance under variable temperature conditions. The developed coupled electro-thermal model is then used for simulating and analyzing the performance of a VRB system operated in conjunction with a wind power plant under real-world conditions

LncRNA–protein interaction prediction with reweighted feature selection

Abstract LncRNA–protein interactions are ubiquitous in organisms and play a crucial role in a variety of biological processes and complex diseases. Many computational methods have been reported for lncRNA–protein interaction prediction. However, the experimental techniques to detect lncRNA–protein interactions are laborious and time-consuming. Therefore, to address this challenge, this paper proposes a reweighting boosting feature selection (RBFS) method model to select key features. Specially, a reweighted apporach can adjust the contribution of each observational samples to learning model fitting; let higher weights are given more influence samples than those with lower weights. Feature selection with boosting can efficiently rank to iterate over important features to obtain the optimal feature subset. Besides, in the experiments, the RBFS method is applied to the prediction of lncRNA–protein interactions. The experimental results demonstrate that our method achieves higher accuracy and less redundancy with fewer features

Validation and Functional Analysis of Reference and Tissue-Specific Genes in Adipose Tissue of Freshwater Drum, <i>Aplodinotus grunniens</i>, under Starvation and Hypothermia Stress

Adipose tissue is critical to the growth, development, and physiological health of animals. Reference genes play an essential role in normalizing the expression of mRNAs. Tissue-specific genes are preferred for their function and expression in specific tissues or cell types. Identification of these genes contributes to understanding the tissue–gene relationship and the etiology and discovery of new tissue-specific targets. Therefore, reference genes and tissue-specific genes in the adipose tissue of Aplodinotus grunniens were identified to explore their function under exogenous starvation (1 d, 2 w, 6 w) and hypothermic stress (18 °C and 10 °C for 2 d and 8 d) in this study. Results suggest that 60SRP was the most stable reference gene in adipose tissue. Meanwhile, eight genes were validated as tissue-specific candidates from the high-throughput sequencing database, while seven of them (ADM2, β2GP1, CAMK1G, CIDE3, FAM213A, HSL, KRT222, and NCEH1) were confirmed in adipose tissue. Additionally, these seven tissue-specific genes were active in response to starvation and hypothermic stress in a time- or temperature-dependent manner. These results demonstrate that adipose-specific genes can be identified using stable internal reference genes, thereby identifying specific important functions under starvation and hypothermic stress, which provides tissue-specific targets for adipose regulation in A. grunniens

Gut microbiota in reintroduction of giant panda

Abstract Reintroduction is a key approach in the conservation of endangered species. In recent decades, many reintroduction projects have been conducted for conservation purposes, but the rate of success has been low. Given the important role of gut microbiota in health and diseases, we questioned whether gut microbiota would play a crucial role in giant panda's wild‐training process. The wild procedure is when captive‐born babies live with their mothers in a wilderness enclosure and learn wilderness survival skills from their mothers. During the wild‐training process, the baby pandas undergo wilderness survival tests and regular physical examinations. Based on their performance through these tests, the top subjects (age 2–3 years old) are released into the wild while the others are translocated to captivity. After release, we tracked one released panda (Zhangxiang) and collected its fecal samples for 5 months (January 16, 2013 to March 29 2014). Here, we analyzed the Illumina HiSeq sequencing data (V4 region of 16S rRNA gene) from captive pandas (n = 24), wild‐training baby pandas (n = 8) of which 6 were released and 2 were unreleased, wild‐training mother pandas (n = 8), one released panda (Zhangxiang), and wild giant pandas (n = 18). Our results showed that the gut microbiota of wild‐training pandas is significantly different from that of wild pandas but similar to that of captive ones. The gut microbiota of the released panda Zhangxiang gradually changed to become similar to those of wild pandas after release. In addition, we identified several bacteria that were enriched in the released baby pandas before release, compared with the unreleased baby pandas. These bacteria include several known gut‐health related beneficial taxa such as Roseburia, Coprococcus, Sutterella, Dorea, and Ruminococcus. Therefore, our results suggest that certain members of the gut microbiota may be important in panda reintroduction

Metagenomic Study Suggests That the Gut Microbiota of the Giant Panda (Ailuropoda melanoleuca) May Not Be Specialized for Fiber Fermentation

Bamboo-eating giant panda (Ailuropoda melanoleuca) is an enigmatic species, which possesses a carnivore-like short and simple gastrointestinal tract (GIT). Despite the remarkable studies on giant panda, its diet adaptability status continues to be a matter of debate. To resolve this puzzle, we investigated the functional potential of the giant panda gut microbiome using shotgun metagenomic sequencing of fecal samples. We also compared our data with similar data from other animal species representing herbivores, carnivores, and omnivores from current and earlier studies. We found that the giant panda hosts a bear-like gut microbiota distinct from those of herbivores indicated by the metabolic potential of the microbiome in the gut of giant pandas and other mammals. Furthermore, the relative abundance of genes involved in cellulose- and hemicellulose-digestion, and enrichment of enzymes associated with pathways of amino acid degradation and biosynthetic reactions in giant pandas echoed a carnivore-like microbiome. Most significantly, the enzyme assay of the giant panda's feces indicated the lowest cellulase and xylanase activity among major herbivores, shown by an in-vitro experimental assay of enzyme activity for cellulose and hemicellulose-degradation. All of our results consistently indicate that the giant panda is not specialized to digest cellulose and hemicellulose from its bamboo diet, making the giant panda a good mammalian model to study the unusual link between the gut microbiome and diet. The increased food intake of the giant pandas might be a strategy to compensate for the gut microbiome functions, highlighting a strong need of conservation of the native bamboo forest both in high- and low-altitude ranges to meet the great demand of bamboo diet of giant pandas