Simultaneous fractionation of multiple classes of polyphenols from honeybush tea using solid-phase extraction

The structural diversity of polyphenols and the inherent limitations of current extraction techniques pose a challenge to extract polyphenols using a simple and green method. Hence, in this study, a method was developed to simultaneously fractionate multiple classes of polyphenols by only varying ethanol-water solutions. Honeybush tea, which is rich in polyphenols, was selected as a model for this study. Solvent extraction followed by solid-phase extraction (SPE) was developed to obtain a polyphenol-rich fraction from six honeybush samples. Based on a gradient elution programme (10%, 30%, 50%, 70% and 90% (v/v) ethanol-water solution) of SPE, the Strata X cartridge showed a better recovery of most targeted polyphenols under 0.9 mL of the drying volume and 1 mL min⁻¹ of the dispensing speed. The elution programme for fractionating most polyphenols was as follows: single elution with 50% ethanol, followed by twice elution with 70% ethanol. The antioxidant capacity was used to analyse the differences among the polyphenol-rich fractions from six honeybush samples. Principal component analysis (PCA) revealed that unfermented C. genistoides (GG) has the greatest antioxidant capacity among the honeybush species studied. Additionally, mangiferin, isomangiferin and vicenin-2 were the main contributors to the antioxidant capacity in six honeybush fractions according to the correlation study.     

Bacteria-Responsive Self-Assembly of Antimicrobial Peptide Nanonets for Trap-and-Kill of Antibiotic-Resistant Strains

Bacterial trapping using nanonets is a ubiquitous immune defense mechanism against infectious microbes. These nanonets can entrap microbial cells, effectively arresting their dissemination and rendering them more vulnerable to locally secreted microbicides. Inspired by this evolutionarily conserved anti-infective strategy, a series of 15 to 16 residue-long synthetic β-hairpin peptides is herein constructed with the ability to self-assemble into nanonets in response to the presence of bacteria, enabling spatiotemporal control over microbial killing. Using amyloid-specific K114 assay and confocal microscopy, the membrane components lipoteichoic acid and lipopolysaccharide are shown to play a major role in determining the amyloid-nucleating capacity as triggered by Gram-positive and Gram-negative bacteria respectively. These nanonets displayed both trapping and killing functionalities, hence offering a direct improvement from the trap-only biomimetics in literature. By substituting a single turn residue of the non-amyloidogenic BTT1 peptide, the nanonet-forming BTT1-3A analog is produced with comparable antimicrobial potency. With the same sequence manipulation approach, BTT2-4A analog modified from BTT2 peptide showed improved antimicrobial potency against colistin-resistant clinical isolates. The peptide nanonets also demonstrated robust stability against proteolytic degradation, and promising in vivo efficacy and biosafety profile. Overall, these bacteria-responsive peptide nanonets are promising clinical anti-infective alternatives for circumventing antibiotic resistance.     

考虑风光互补的输储联合规划方法研究

针对可再生能源电站和输电网的联合规划问题,提出了一种考虑风光互补特性、储能系统的运行特性和输电线路规划的输电网大规模接纳风能和光能的联合规划方法,其规划目标是在大规模风光并网的前提下,使年弃风成本、年弃光成本、储能投资成本和输电线路扩建成本的总成本最小;建立提升风光接纳能力的储能配置与输电线路联合规划模型,提出风光互补程度、电源损失率和风光储混合电力系统贡献率3个指标来进行评价,并进行算例分析。仿真结果表明,所提输储联合规划方法可以有效地限制对原有网架的扩建,合适风光配比可以进一步节约电网投资和运行成本,并提高系统的稳定性和有效性。     

An efficient secure proxy verifiably encrypted signature scheme

Verifiably encrypted signature is an important cryptographic primitive, it can convince a verifier that a given ciphertext is an encryption of signature on a given message. It is often used as a building block to construct an optimistic fair exchange. In this paper, we propose a new concept: a proxy verifiably encrypted signature scheme, by combining proxy signature with a verifiably encrypted signature. And we formalize security model of proxy verifiably encrypted signature. After a detail construction is given, we show that the proposed scheme is provably secure in the random oracle model. The security of the scheme is related to the computational Diffie–Hellman problem.     

混合监测技术在并行与分布式性能监测中的应用

主要介绍了混合监测技术在并行与分布式系统性能分析评价中的应用。分析比较了常用的几种监测技术,给出了各自的优缺点,介绍了混合监测中的事件的定义,自动装备的过程。事件的采集和分析这向个关键步骤,提出装备的层交化。最后提出了混合监测中会遇到一些问题并给出了相应的解决方法。     

开机过程中的水电站厂房振动分析

本文根据水电站厂房及机组结构开机过程原型观测资料,对水工结构振动情况进行分析,并详细探讨了机组起动过程中的轴向力、扭矩、不平衡力等几种主要荷载的变化情况,给出它们的幅值的近似估算，在此基础上,提出一种计算开机过程中厂房结构动力响应的方法，并将通过该方法结合有限元模型计算出的数值结果与实测数据进行比较,证明该方法是可行的。     

MS-3监测系统对Java多线程程序的监测

多线程是Java语言的重要特点之一，但是Java语言的线程调度是由操作系统来完成的，开发人员无法获知各线程的具体执行情况，而常规的软件调试工具对线程的分析会对目标程序有较大的干扰。该文利用基干事件的混合监测系统MS-3，对Java多线程程序的各线程行为进行了精确的分析。     

Evaluation of copy-move forgery detection: datasets and evaluation metrics

Creating copy-move forgery became even easier using a wide range of software and platforms. Many algorithms have been proposed to solve the problem, but each one of those algorithms has its own drawbacks. Researchers face many challenges in developing copy-move detection algorithms, and in this paper, we focus on two challenges. The first is the benchmark dataset, and the second involves evaluation metrics. In this paper, we investigate the available copy-move datasets and their advantages and disadvantages. In addition, we discuss the different metrics that have been used by researchers to evaluate the copy-move forgery detection (CMFD) algorithms. On that basis, we suggest the standard specifications of the appropriate copy-move dataset and the metrics that should be used to evaluate the detection algorithms. The findings of this paper will help researchers evaluate their algorithms effectively and fairly essential for developing reliable algorithms.     

Motion analytics of zebrafish using fine motor kinematics and multi-view trajectory

Zebrafish is a useful animal model for studying human diseases such as muscle disorders. However, manual monitoring of fish motion is time-consuming and prone to subjective variations. In this paper, an automatic fish motion analytics framework is proposed. The proposed framework could be exploited to help validate zebrafish models of transgenic zebrafish that express human genes carrying mutations which lead to muscle disorders, thus affecting their ability to swim normally. To differentiate between wild-type (normal) and transgenic zebrafish, the proposed framework consists of two approaches to exploit discriminative spatial–temporal kinematic features which are extracted to represent zebrafish movements. First, the proposed approach studies precise quantitative measurements of motor movement abnormalities using a camera with the capability to record videos with high frames rates (up to 1,000 frames per second). This differs from previous works, which only tracked each fish as a single point over time. Second, the proposed approach studies multi-view spatial–temporal swimming trajectories. This differs from previous works which typically only considered single-view analysis of fish swimming trajectories. The proposed motion features are then incorporated into a supervised classification approach to identify abnormal fish movements. Experimental results have shown that the proposed approach is capable of differentiating between wild-type and transgenic zebrafish, thus helping to validate the zebrafish models.     

Comparative characterization and cytotoxicity study of TAT-peptide as potential vectors for siRNA and Dicer-substrate siRNA

Recently, a newly discovered Dicer-substrate siRNA (DsiRNA) demonstrates higher potency in gene silencing than siRNA but both suffer from rapid degradation, poor cellular uptake and chemical instability. Therefore, Tat-peptide was exploited to protect and facilitate their delivery into cells. In this study, Tat-peptide was complexed with siRNA or DsiRNA through simple complexation. The physicochemical properties (particle size, surface charge and morphology) of the complexes formed were then characterized. The ability of Tat-peptide to carry and protect siRNA or DsiRNA was determined by UV-Vis spectrophotometry and serum protection assay, respectively. Cytotoxicity effect of these complexes was assessed in V79 cell line. siRNA-Tat complexes had particle size ranged from 186?±?17.8 to 375?±?8.3?nm with surface charge ranged from ?9.3?±?1.0 to +13.5?±?1.0?mV, depending on the Tat-to-siRNA concentration ratio. As for DsiRNA-Tat complexes, the particle size was smaller than the ones complexed with siRNA, ranging from 176?±?8.6 to 458?±?14.7?nm. Their surface charge was in the range of +27.1?±?3.6 to +38.1?±?0.9?mV. Both oligonucleotide (ON) species bound strongly to Tat-peptide, forming stable complexes with loading efficiency of more than 86%. These complexes were relatively non cytotoxic as the cell viability of ～90% was achieved. In conclusion, Tat-peptide has a great potential as siRNA and DsiRNA vector due to the formation of stable complexes with desirable physical characteristics, low toxicity and able to carry high amount of siRNA or DsiRNA.