Suspended Emulsion Copolymerization of Acrylonitrile with Methyl Acrylate: Effects of Reaction Parameters on the Polymerization

Acrylonitrile/methyl acrylate copolymers were synthesized by suspended emulsion polymerization with water as dispersed phase and monomers as continuous phase, potassium peroxydisulphate (KPS) as initiator, Span-80 as emulsifier, and poly(vinyl alcohol) (PVA) as suspending agent. Effects of reaction parameters such as water/monomer mass ratio, concentration of initiator, polymerization temperature and agitation rate on polymerization conversion and the particle size distribution of acrylonitrile/methyl acrylate copolymers were studied. It was found that polymerization conversion increased with an increase of water/monomer mass ratio, concentration of initiator and polymerization temperature, while the agitation rate had no significant effect on the polymerization conversion. Particle size distribution became narrower with an increase of water/monomer mass ratio and agitation rate. Under the same initiator concentration and polymerization temperature, particle size distribution became wider along with polymerization time. The differential scanning calorimetry (DSC) results indicated that the peak temperature of the copolymers decreased with increasing MA content.     

Removal of Rhodamine B,a Cationic Dye From Aqueous Solution Using Poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) Nanotubes

Poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanotubes were evaluated as an efficient adsorbent for the removal of Rhodamine B (RhB), a cationic dye from aqueous solution. The as-synthesized adsorbent (PZS nanotubes) were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and N₂ adsorption/desorption isotherms. The factors influencing the adsorption efficiency and capacity had been systematically studied. Results showed that the adsorption was highly dependent on temperature, initial RhB concentration and adsorbent dose. Effects of initial solution pH indicate that the adsorption can proceed in both basic and acidic environment. The equilibrium absorption capacity at 25°C can reach up to 35.58 mg/g within 60 min implying the adsorption procedure was highly rapid. The kinetic data was better described by the pseudo-second-order model with the correlation coefficient (R² = 0.9981), and the adsorption process followed Weber's intraparticle model, indicating the adsorption process could be divided into two stages. Results also showed that the adsorption equilibrium obeyed the Langmuir isotherm, and the value of equilibrium parameter R_L suggested that the PZS nanotubes were an efficient adsorbent for the removal of RhB from aqueous solution.     

笔法与结构对楷书文字美学品质影响的量化研究

笔法与结构对文字观感的影响是中国书法文化的重要研究命题,也与数字书法领域审美评价技术相关联。但以往对该命题主要为定性讨论。本文结合计算机样条曲线及审美量表等技术,设计了一种实验方法对其进行量化研究。首先,选取78个高频字的6种有代表性的楷书体文字作为样品,自编软件并招募测试人员对其标注结构特征点,并用参数曲线建模输出“去除笔法”后的样品图,再进一步经严格定义的“统一结构”操作进行处理,共获得3组样品图,每组468幅。然后,编制审美量表,招募测试者以随机分配的方式对3组样品评测美感和风格。最后,对评测数据进行统计分析。结果显示,对于楷书文字的风格而言,笔法的影响远高于结构;对于文字的美感而言,笔法的作用也大于结构,但影响有限。该结果局限于实验选定的几种经典的楷书文字,且其定义的“去除笔法”和“统一结构”并不能完全涵盖以往经验理论中的相关概念范围。研究表明,自然学科的方法可用于研究书法学中的命题。     

基于机器学习的软件测试经验库的构建

当前软件测试用例的设计在很大程度上依赖于测试人员的个人经验和理论水平,给测试结果引入了很大的不确定性,无法有效的保证软件测试的质量。能够在有效的时间内覆盖尽可能多的测试项,是决定测试是否成功的标志,而测试进度与测试质量是软件测试过程中的一对互斥因素。为平衡这个问题,文章提出了基于机器学习的软件测试经验库的构建,并在工程中进行了实践应用。测试策略经验库的建立能够有效的提高软件测试的效率,保证测试策略的质量。     

基于K-Means++和Elman神经网络的低压台区线损计算方法

为了解决低压台区线损计算在理论上因线路复杂、用户众多以及数据获取困难等带来计算难度与精度不足的问题,提出了一种结合改进K-Means⁺⁺算法与Elman神经网络的创新计算方法。深入分析了低压台区线损的决定因素,并依据相关性分析构建了线损的关键特征指标集。采纳主成分分析方法实施数据降维,简化数据结构。通过改进的K-Means⁺⁺算法对数据集进行有效聚类,优化模型训练过程。同时,整合粒子群优化算法进一步提升Elman神经网络的性能。通过对实际数据进行仿真验证,结果证实所提出的方法在训练效率和计算精度方面表现优异。     

Exploration of Habitat-Related Chemical Markers for Stephania tetrandra Applying Multiple Chromatographic and Chemometric Analysis

Geo-authentic herbs refer to medicinal materials produced in a specific region with superior quality. Stephania tetrandra S. Moore (S. tetrandra) is cultivated in many provinces of China, including Anhui, Zhejiang, Fujian, Jiangxi, Hunan, Guangxi, Guangdong, Hainan, and Taiwan, among which Jiangxi is the geo-authentic origin. To explore habitat-related chemical markers of herbal medicine, an integrated chromatographic technique including gas chromatography-mass spectrometry (GC-MS), ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) and ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) combined with chemometric analysis was established. The established methods manifested that they were clearly divided into two groups according to non-authentic origins and geo-authentic origins, suggesting that the metabolites were closely related to their producing areas. A total of 70 volatile compounds and 50 non-volatile compounds were identified in S. tetrandra. Meanwhile, tetrandrine, fangchinoline, isocorydine, magnocurarine, magnoflorine, boldine, and higenamine as chemical markers were accurately quantified and suggested importance in grouping non-authentic origins and geo-authentic origins samples. The discriminatory analysis also indicated well prediction performance with an accuracy of 80%. The results showed that the multiple chromatographic and chemometric analysis technique could be used as an effective approach for discovering the chemical markers of herbal medicine to fulfill the evaluation of overall chemical consistency among samples from different producing areas.     

以DNA为模板的银纳米簇荧光检测及逻辑门的构建

以DNA为模板,合成了具有荧光性质的银纳米簇(DNA-Ag NCs),利用荧光光谱、紫外光谱和红外光谱等手段对其进行了表征.基于DNA-Ag NCs与离子相互作用时产生的荧光变化可实现对离子浓度的检测.实验结果表明,在最佳实验条件下,Ni²⁺及Hg²⁺的浓度与DNA-Ag NCs荧光强度呈线性关系;并验证了该荧光探针用于检测自来水样品中汞离子和镍离子的实用性.由于以DNA为模板的DNA-Ag NCs能够响应多种刺激,如Ni²⁺,S^2-,Hg²⁺和p H等,利用相应的荧光强度可构建多输入的DNA-Ag NCs逻辑门及其组合逻辑门.当荧光输出强度(I_output)>初始荧光强度(I_origin)时,设定输出为1,采用各种刺激及其组合作为输入,构建了YES,INH和组合的NOR与INH逻辑门.而只有当I_output≥I_origin时定义为输出为1,可建立NOT,NOR,组合的IMP加上NOR...     

Polydopamine(PDA)-activated cobalt sulfide nanospheres responsive to tumor microenvironment(TME)for chemotherapeutic-enhanced photothermal therapy

Most recently,cobalt sulfide(CoS) nanospheres(NSs) have been demonstrated as an ideal high-efficient photothermal agent for tumor elimination.Howeve r,the surface of CoS NSs is lack of functio nal chemical groups or active radicals to incorporate therapeutic agents,which tremendously hinders their versatile utilization in medical field.Here,surface activation of CoS NSs was realized through the growth of polydopamine(PDA) in situ via alkaline-triggered polymerization.Upon the formation of CoS@PDA NSs,thiol-polyethylene glycol(SH-PEG) and chemotherapeutic agent of doxorubicin(DOX) were loaded onto the particle surface by means of π-π electrostatic interaction and Michael addition reactions.Assynthesized CoS@PDA/PEG/DOX(CoPPD) NSs exhibited an admirable photothermal property and high loading capacity of DOX(44.6%).Furthermore,drug release can be accelerated under a more acidic pH condition mimicking tumor microenvironment(TME),ascribed to the protonation of amino group in DOX molecules.Finally,a strong chemotherapeutic-enhanced photothermal therapeutic effect was demonstrated toward solid tumor under near-infrared(NIR) light irradiation without causing significant systemic toxicity.In this regard,this paradigm may offer valuable guidance for the design of multifunctional CoS-based nanoagents for medical treatment.     

基于SESAM的3 μm波段被动调Q光纤激光器

基于半导体可饱和吸收镜,实现了3 m波段被动调Q光纤激光器平均功率瓦级输出。激光器最大平均功率为1.0 W,对应的最大脉冲能量及最大峰值功率分别为6.9 J和21.7 W。激光器斜效率为17.8%,最高重复频率为146.3 kHz,最小脉宽为315.0 ns。     

The application of perovskite materials in solar water splitting

Solar water splitting is a promising strategy for sustainable production of renewable hydrogen, and solving the crisis of energy and environment in the world. However, large-scale application of this method is hampered by the efficiency and the expense of the solar water splitting systems. Searching for non-toxic, low-cost, efficient and stable photocatalysts is an important way for solar water splitting. Due to the simplicity of structure and the flexibility of composition, perovskite based photocatalysts have recently attracted widespread attention for application in solar water splitting. In this review, the recent developments of perovskite based photocatalysts for water splitting are summarized. An introduction including the structures and properties of perovskite materials, and the fundamentals of solar water splitting is first provided. Then, it specifically focuses on the strategies for designing and modulating perovskite materials to improve their photocatalytic performance for solar water splitting. The current challenges and perspectives of perovskite materials in solar water splitting are also reviewed. The aim of this review is to summarize recent findings and developments of perovskite based photocatalysts and provide some useful guidance for the future research on the design and development of highly efficient perovskite based photocatalysts and the relevant systems for water splitting.