Biochemical characterisation of an aminopeptidase with highest preference for lysine from Japanese flounder skeletal muscle

An aminopeptidase was purified from Japanese flounder skeletal muscle to homogeneity by ammonium sulphate fractionation and three chromatographies. The enzyme was approximately 100 kDa with isoelectric point of 5.7 as estimated by two-dimensional polyacrylamide gel electrophoresis. Its optimum temperature and pH were 45 °C and 7.5, respectively. According to peptide mass fingerprinting study, the enzyme revealed high identity to a puromycin-sensitive aminopeptidase. It had a broad specificity toward aminopeptidase substrates and preferred to hydrolyse Lys-MCA with k_cat/K_m of 8.1 × 10⁶ M^?1 s^?1, and the activation energy (E_a) of 72.5 kJ M^?1. Metal-chelating agents effectively inhibited the enzyme activity, and Zn²⁺, Mn²⁺ and Co²⁺ significantly restored the apoenzymatic activity dialysed by EDTA, whilst inhibitors to other proteinases did not show much effect. Furthermore, bestatin strongly inhibited its activity. These results indicate that the purified enzyme is a metalloaminopeptidase which would possibly contribute to free amino acids increase in fish muscle.     

Gradient microstructure of TC21 alloy induced by hydrogen during hydrogenation

Through melt hydrogenation, a gradient microstructure (α″ + α′)/(α + β_H) has been observed in TC21 alloy. The addition of hydrogen induces martensite transformation and increases the volume fraction of β. It is found that the absorption process of hydrogen atoms can be divided into melting and cooling stages. During cooling, the continuous absorption of hydrogen and the corresponding decrease of freezing point of melt extend solidification time of melt and lead to hydrogen enrichment in the upper of the specimen, which induces the formation of the gradient structure. The hydrogenated TC21 alloy shows higher thermoplasticity compared with the unhydrogenated TC21 alloy. The flow stress of the upper part of the hydrogenated alloy is lower than that of the center part. A gradual variation has been observed in the microhardness along the gradient direction due to variation in the microstructure. The microhardness of the upper surface drops about 45% with 14.6 at.%H.     

Dynamic foreground detection based on improved Codebook model

Foreground detection method based on improved Codebook algorithm is discussed in this paper: first of all, transform RGB colour space into YCbCr colour space to make chromaticity convergent, and cope with illumination changing. Second, search for the CodeWords matching with the pixel values of the YCbCr to update the algorithm, so as to ensure the foreground detection effect. Then apply random abandon value method to delete the CodeWords that have not been accessed for a long time, reduce memory consumption and improve processing speed. Finally, conduct experiments on the infrared imagery and the colour image, respectively, to make foreground detection. The results demonstrate that the model and algorithm presented in this paper can make better foreground detection and reduce memory consumption. Meanwhile, compare this method with other algorithms to prove its advantages.     

Highly efficient electrocatalytic hydrogen production via MoSx/3D-graphene as hybrid electrode

Molybdenum sulfide (MoS_x) has recently emerged as a promising catalyst for the hydrogen evolution reaction (HER) in water splitting that may replace the noble metal, such as platinum, as a cost-effective and high catalytic materials. It has been reported that two-dimensional structured MoS_x exhibit significant amount of exposed S-edge, which can be an active electrocatalytic catalyst for hydrogen production. However, the current reports mainly focusing on the planar electrode, where the catalyst utilization and the number of active sites are limited due to the lower exposed specific surface area (SSA) of supporting electrodes. In this work, we utilize the freeze-drying method to produce a porous three-dimensional (3D) structure assembled by graphene flakes. The as-prepared 3D graphene scaffold shows high surface area, high porosity while low density, which makes it as an ideal conductive electrode for supporting of MoS_x catalysts. Moreover, it was found out that the crystallinity of MoS_x, controlled by thermolysis temperature of thiosalts precursor ((NH₄)₂MoS₄), shows significantly influence the performance of HER. The optimized annealing temperature for the designed hybrid electrodes (MoS_x/3D-graphene) was found to create a lot of active sites, which facilitate the electrocatalytic performance for water splitting (overpotential of 163 mV @10 mA/cm² and a Tafel slope of 41 mV/dec). The study provides a potential material, which could pave the way for future applications of hydrogen energy.     

High‐Precision Temperature‐Controllable Metal‐Coated Polymeric Molds for Programmable,Hierarchical Patterning

Nanofabrication is an indispensable process in nanoscience and nanotechnology. Unconventional lithographic techniques are often used for fabrication as alternatives to photolithography because they are faster, more cost‐effective, and simpler to use. However, these techniques are limited in scalability and utility because of the collapse of preprinted structures during step‐and‐repeat processes. This study proposes a new class of temperature‐controllable polymeric molds that are coated with a metal such that any site‐specific patterning can be accomplished in a programmable manner using selective contact‐dewetting lithography. The lithography allows sub‐100 nm patterning, step‐and‐repeat processing, and hierarchical structure fabrication. The programmable feature of the lithography can be utilized for the structural coloring and shaping of objects. Large‐area programmable patterning, semiconductor device manufacturing, and the fabrication of iridescent security devices would benefit from the unique features of the proposed strategy.     

Improved electrochemical performance of a cyclic ultracapacitor using slurry electrodes under various flow conditions

A cyclic ultracapacitor is a promising energy storage device that can be used for grid energy storage. The cyclic ultracapacitor combines the advantages of both ultracapacitors and flow batteries, enabling rapid charging and large‐scale energy use. To improve the electrochemical performance under the flow condition, it is necessary to find a more electrical active material and design a flow cell that minimizes the resistance. In this study, we investigate the effects of changing the ratio of the active material in a slurry electrode under various operating conditions. Slurry electrodes were prepared with different ratios of active material and conductive additive but with a fixed electrolyte amount. Voltage–time curves of both a single and a stack‐flow cell in the constant‐current mode were obtained to analyze the relationship between the active materials ratio and the cell performance. Having more adsorption sites according to the active material amount is more important than increasing the electric conductivity by the conductive additive amount with regard to cell performance capabilities in a low resistance condition such as a non‐flow mode. However, higher electrical conductivity on a slurry electrode is more beneficial to improve the electrochemical performance in the stack‐flow mode, which has harsh resistance levels. Copyright © 2017 John Wiley & Sons, Ltd.     

In vitro culture of Boletus badius as a source of indole compounds and zinc released in artificial digestive juices

Food Science and Biotechnology - The objective of this study was to obtain the in vitro cultures of Boletus badius under controlled conditions and investigate the release of indole compounds and...     

A survey on decision making for task migration in mobile cloud environments

The key idea of MCC is using powerful back-end computing nodes to enhance capabilities of small mobile devices and provide better user experiences. An effective and widely used approach to realize this is task migrations. Decision making is an important aspect of migrations which affects the feasibility and effectiveness of task migrations. There have been a number of research efforts to MCC which help make decisions for task migrations. In this paper, we present a comprehensive survey on decision making for task migrations in MCC, including decision factors and algorithms. We observe that there are still some challenges such as comprehensive context awareness, unified migration standards, large-scale experiments, more involvement of latest achievements from artificial intelligence, and flexible decision-making mechanisms. The paper highlights these issues and challenges to attract more efforts to work on MCC.