FPDock: Protein–protein docking using flower pollination algorithm

Proteins play their vital role in biological systems through interaction and complex formation with other biological molecules. Indeed, abnormalities in the interaction patterns affect the proteins’ structure and have detrimental effects on living organisms. Research in structure prediction gains its gravity as the functions of proteins depend on their structures. Protein–protein docking is one of the computational methods devised to understand the interaction between proteins. Metaheuristic algorithms are promising to use owing to the hardness of the structure prediction problem. In this paper, a variant of the Flower Pollination Algorithm (FPA) is applied to get an accurate protein–protein complex structure. The algorithm begins execution from a randomly generated initial population, which gets flourished in different isolated islands, trying to find their local optimum. The abiotic and biotic pollination applied in different generations brings diversity and intensity to the solutions. Each round of pollination applies an energy-based scoring function whose value influences the choice to accept a new solution. Analysis of final predictions based on CAPRI quality criteria shows that the proposed method has a success rate of 58% in top10 ranks, which in comparison with other methods like SwarmDock, pyDock, ZDOCK is better. Source code of the work is available at: https://github.com/Sharon1989Sunny/_FPDock_.     

表面活性剂辅助合成CdWO4纳米棒和纳米线

以Na₂WO₄•2H₂O和CdCl₂ 为主要原料, 分别在十六烷基三甲基溴化铵(CTAB)和十二烷基苯磺酸钠(SDBS)表面活性剂中, 在180 ℃反应16 h, 水热制备了CdWO₄纳米棒和纳米线. 利用X射线粉末衍射(XRD)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)等手段对产物进行了表征, 并对其在室温下的发光特性进行了测定. 实验结果表明: 产物均为具有单斜结构的单相CdWO₄. 其中CdWO₄纳米棒具有单晶属性, 平均粒径约为63 nm, 长度近1 µm; 而CdWO₄纳米线具有多晶特性, 平均粒径约为12 nm, 长度达十几微米. 当激发波长为253 nm时均有460 nm强的发射峰, 其中CdWO₄单晶纳米棒的发光强度大于CdWO₄多晶纳米线. 分别对CdWO₄纳米棒和纳米线形成的可能机理进行了初步分析.     

Colorimetric detection of hepatitis B virus (HBV) DNA based on DNA-templated copper nanoclusters

DNA detection plays an important role in early diagnosis of genetic disease. The conventional detection methods of DNA are based on expensive equipment, which do not meet the demands of developing countries. Thus, we developed a colorimetric method, which could be observed with naked eye and used copper nanoclusters for cost-effective. Moreover, the target of this method is the DNA in Hepatitis B virus that is one of the most popular chronic viral infections in developing countries over the past years. Our method was sensitive and the limit of detection was 12 × 10⁹ molecules. Three-base-pair mismatches target DNA was detected easily. These results revealed the favorable sensitivity and selectivity of this approach. Most importantly, our method may have potential applications in correct diagnosis of genetic disease and monitoring of gene therapy in the poverty-stricken areas.     

Modified Capillary Electrophoresis for Highly Sensitive and Selective Detection of Hg2+ in Natural Water

A novel capillary with high sensitivity and selectivity for mercury ion detection based on modified nanosize silica has been designed and synthesized. The obtained modified capillary was applied to separate and determine mercury ion by capillary electrophoresis with a laser‐induced fluorescence detector. The optimal experimental conditions were determined by evaluating various controlling factors: running buffer hexamine‐HCl 15 mmol L^?1, pH=5.2, separation voltage 30 kV and temperature 25 °C. The modified capillary exhibited excellent sensitivity and selectivity for Hg2+ over other coexisting metal ions (K⁺, Ag⁺, Ca2⁺, Mg²⁺, Ba²⁺, Ni²⁺, Cd²⁺, Pb²⁺ and Zn²⁺ increased to 10000 times of Hg²⁺, Cu²⁺ increased to 5000 times) in aqueous solution, and was successfully applied to the determination of Hg²⁺ in natural water samples and displayed satisfactory results.     

任意支承梁的差分离散系统及其刚度矩阵的振荡性

应用二阶中心差分公式,建立了任意支承的Euler梁的差分离散系统,导出了与之等效的弹簧-质点-刚杆模型．利用振荡矩阵理论,证明了上述系统的刚度矩阵的符号振荡性,完整的导出了正系统的充分必要条件．     

邻二氮菲荧光法测定氯碱厂阳极泥中痕量钌

研究了在乙酸-乙酸钠缓冲溶液中,在盐酸羟胺还原剂存在下,于水浴中加热近沸,保温5 min,钌与邻二氮菲形成1∶3络合物。它的荧光激发波长峰为448 nm,发射波长峰为586 nm。钌与荧光强度线性范围为0～10μg·(25 mL)-1。样品中的钌通过蒸馏分离,方法应用于氯碱厂阳极泥中钌的含量分析,具有满意的分析结果。     

Theoretical Studies of Optical Properties of Silver Nanoparticles

Optical properties of silver nanoparticles such as extinction, absorption and scattering efficiencies are studied based on Green＇s function theory. The numerical simulation results show that optical properties of silver nanoparticles are mainly dependent on their sizes and geometries; the localized plasmon resonance peak is red shifted when the dielectric constant of the particle＇s surrounding medium increases or when a substrate is presented. The influences of wave polarizations, the incident angles of light, the composite silver and multiply-layers on the plasmon resonance are also reported. The numerical simulation of optical spectra is a very useful tool for nanoparticle growth and characterization.     

Periodic solution of a neutral delay model of single-species population growth on time scales

By using a fixed point theorem of strict-set-contraction, we present some sufficient conditions for the existence of at least one positive ω-periodic solution to a neutral delay model of single-species population growth on time scales. The significance of the present paper is that we address an open problem introduced by Kuang [Kuang Y. Delay differential equations with applications in population dynamics. New York: Academic Press; 1993] on time scales.     

不同泵浦光下Nd:GdVO4晶体输出特性

为研究808 nm和879 nm两种泵浦光对Nd:GdVO4晶体激光输出特性的影响,并比较两种不同波长泵浦所得连续输出光的效率高低,分析了Nd:GdVO4晶体的能级结构和两种泵浦光作用下的激光输出特性,发现在879 nm也有较强的吸收峰.用808 nm和879 nm两种不同波长泵浦Nd:GdVO4晶体的过程是不同的,808 nm泵浦是一种间接方式能量转移的过程,在此过程中有明显的热负载产生.而879 nm泵浦是将粒子直接激励到激光辐射上能级,降低无辐射弛豫过程产生的热量.从理论上可知,879 nm的泵浦量子效率要高于808 nm的泵浦量子效率,对减少晶体的热产生有很强的优势.实验中采用激光二极管端面泵浦Nd:GdVO4晶体直腔方案,研究了两种不同泵浦光泵浦Nd:GdVO4晶体以获得1 063 nm的连续光,得到了两种光抽运时的斜效率,发现在同样实验条件下,879 nm泵浦的输出光斜效率在小功率泵浦时略高于808 nm|而在大功率泵浦的情况下明显高于808 nm,最高达到38%.同时,在808 nm抽运时,实验上获得了1 341 nm波长的激光,为光通讯的应用提供了一种光源.     

Synthesis of ion-imprinted mesoporous silica gel sorbent for selective adsorption of copper ions in aqueous media

A new Cu(II) ion-imprinted sorbent was synthesized by a surface imprinting technique and characterized by FT-IR and SEM. Compared to the non-imprinted sorbent, the Cu(II) ion-imprinted sorbent had a higher adsorption capacity and selectivity for Cu(II). The static adsorption capacity of the Cu(II) ion-imprinted sorbent and non-imprinted sorbent for Cu(II) were 84.5 and 46.5 μmol?g^?1, respectively. The best selectivity coefficient over Zn(II) or Cd(II) ion was over 12. The relative selectivity coefficients of the sorbent for Cu(II) in the presence of Zn(II) and Cd(II) were 13 and 35, respectively. Furthermore, the new sorbent possessed a fast kinetics for Cu(II) sorption from aqueous solution with saturation time of <30 min, and could be used repeatedly. The standard deviation for 11 replicate determinations of 0.5 mg?L^?1 Cu(II) was 0.8%. This new Cu(II) ion-imprinted sorbent can be used as an effective solid-phase extraction material for the selective preconcentration and separation of Cu(II).