Physical and Chemical Characterizations of Rubber Latex Cup Bottom Oil

Rubber latex is an important economic resource. However, the residues from its harvesting are thrown away, even though they contain lipids that can be recycled. This recovery of the residues from the bottom of the cup requires first and foremost their characterization. The aim of this study is therefore to determine the main physical and chemical characteristics of rubber latex cup bottom oil. Oil’s physical parameters determination shows that it has a density of 951 kg∙m−3, a kinematic viscosity of 48.57 cSt and a water content of 0.0845%. Chemical parameters, meanwhile, indicate that this cup bottom residue has a fat content of 95.96%, an acid number of 2.805 mg KOH/g and an iodine number of 92.42 g I2/100g. Therefore, rubber latex cup bottom oil can be used in the formulation of biofuels, biolubricants, paints, varnishes, alkyd resins, polishing oils, soaps, and insecticides.

基于LaTeX渲染的微积分在线测试小程序设计与实现

为解决传统微积分在线考试系统中数学公式显示不清、存储空间占用大的问题,文章提出了一种基于LaTeX渲染的微信小程序解决方案。相较于传统的图片存储方式,LaTeX渲染可以显著提高公式显示质量,并减少存储空间。该系统可用于微积分课程的过程性考核,实现个性化学习跟踪,提高教学效率。

Formulation of Motor Oil from Blends of Rubber Latex Cup Bottom Oil (RLBO) and Used Frying Oil (UFO)

Most motor oils are made from mineral oils derived from petroleum, the reserves of which are limited and exhaustible. The aim of this study is to produce and characterize motor oil formulations based on mixtures of rubber latex cup bottom oil (RLCBO) and used frying oil (UFO). The results show that these formulations have a density between 0.91 and 0.92. These densities evolve linearly with the proportion of cup bottom oil and temperature. Similarly, the kinematic viscosity of the blends follows an exponential relationship with temperature. By plotting the logarithm of these kinematic viscosities against the inverse of the temperature, we were able to determine the activation energy of the various blends and deduce that the formulations behave Newtonian.

STUDIES ON POLYSILOXANE-POLYSTYRENE COMPOSITE LATEXES

Polysiloxane-polystyrene composite latexes were prepared by two-stage emulsionpolymerization. Polymerization of styrene in swollen polysiloxane latex particles were studied.Formation of simple polystyrene particle in the 2nd-stage polymerization depends on the particlesize of the lst-stage latex and the polymerization temperature. Polystyrene domains in thevulcanizates reinforce the silicone rubbers effectively.

Antimicrobial Activity of Fruit Latexes from Ten Laticiferous Plants

In the present investigation antibacterial activity of latexes from ten Indian plant species Spondias dulcis (Amra), Diospyros melanoxylon (Tendu), Terminalia bellirica (Wahera), Ficus glomerata (Gular), Phyllanthus emblica (Awla), Thevetia nerifolia (Kaner), Carica papaya (Papita), Calotropis procera (Ak), Ficus benghalensis (Bargad), Atrocarpus heterophyllus (Kathal) collected from Go-rakhpur, North India were determined in various in vitro systems. MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) values were determined in growth inhibitory bioassays by using different increasing concentrations of various latex extracts. Latex samples were diluted by using serial micro dilution method up to 10-10 method with Luria broth culture medium. These values were obtained significantly 2 - 3 times lower than that of broad spectrum antibiotic drugs. Besides this, inhibition zone diameters were measured in agar disc diffusion assay. A known volume i.e. 0.1 - 20 μg/μl of each latex were coated on separate sterile filter paper discs (Whatman No. 1) measuring 6 mm in size. Latex fractions registered significantly higher growth inhibition than that of broad spectrum antimicrobial drugs. Present study indicates the potential use of shows that both latex and its components and latex as are valuable source of medicinal products/active principles that can be used for treatment of life threatening infectious diseases. Because of higher inhibitory and cidal potential obtained in latexes than the synthetic drugs these that could lead to become efficient phytomedicines mainly to have and develop as complete drug formulations against to control infectious microbes.

HIGH SOLIDS-CONTENT NANOSIZE POLYMER LATEXES MADE BY A MODIFIED EMULSION COPOLYMERIZATION

Polymer nanoparticles were prepared in the methyl methacrylate (MMA)/buty lmethacrylate (BA) emulsion copolymerization process by a modified microemulsion copolymerization method. 2-Hydroxyethyl methacrylate(HEMA), acrylate (AA) and methyl acrylate (MAA) were used as reactive cosurfactants. With this process high polymer: surfactant weight ratios (40:1 or greater),relatively concentrated (~30wt. %) latexes and small (~60nm) particle diameters were obtained.Properties of the latexes were characterized by TEM, DSC, dynamic light scattering, and IR spectroscopy.

Synthesis of Monodisperse Latexes to Create Immunodiagnostic Drugs

The aim of this work was the synthesis of monodisperse latexes based on methyl methacrylate.To achieve this goal,methyl methacrylate was polymerized in an emulsifier-free static heterogeneous monomer-water system in the presence of hydroquinone and potassium persulfate.The size of the latex particles was determined by electron microscopy.Monodisperse latexes with a diameter of about 100 nm were synthesized as a result.

Toxic Effects of Ficus benghalensis Latex Based Combinatorial Formulations on Various Enzymatic Parameters in Indian White Termite Odontotermes obesus

In the present investigation, various bioassays were conducted to evaluate the alteration in levels of various enzymes i.e. alkaline phosphatase, acid phosphatase, glutamate oxaloacetate transaminase, glutamate pyruvate transaminase and acetylcholinesterase. For this purpose worker termites were treated with sub-lethal doses of 40% and 80% of 24 hrs LD50 of latex-based combinatorial formulations and observations were taken at 4 hours intervals up to 24 hours. Ficus benghalensis crude latex and its combinatorial mixtures, like C-MLT-A, CU-MLT-A, AQ-MLT, P-MLT and EA-MLT significantly altered the level of enzymes in Odontotermes obesus and this effect found time and dose-dependent. Reduction or increase in enzymes was calculated by using the corresponding control. The maximum decrease in acid phosphatase level was observed at 16 h when termites were treated with 80% of LD50 of B-MLT-B and P-MLT i.e. 82.84% at 16 h of treatment. A similar dose caused a very slight decrease in glutamate pyruvate transaminase at 4 h of treatment but with the increase in time. Further decrease was noted in other successive treatments that were significant at p > 0.05. Similarly, 40% and 80% of LD50 of the C-MLT-B mixture caused significant (p > 0.05) decrease in alkaline phosphatase and acid phosphatase level at 16 h treatment i.e. 93.42%, 89.46% and 95.89%, 88.17% respectively. The level of acetylcholinesterase was also found to be decreased when termites were treated with 40% and 80% of LD50 of C-MLT-B mixture i.e. 92.72% and 97.27% respectively. All the above alterations noted in levels of various enzymes confirm the action of latex ingredients on worker termites that were anti-feedant or deterrent types. These ingredients can be used to control not only termites but also other phytophagous insects.

基于LaTeX的高等数学题库建设与试卷生成

题库管理与出试卷是高校老师工作中的重要组成部分.传统的管理与操作方法费时费力,同时在试题重复率、格式化与标准化等方面相对难以控制.针对中文理工科组卷,利用Te X系统实现题库管理与组卷,能大大减轻老师工作量.在分析高校题库与试卷管理现状及高校理工科试卷特点等基础上,利用LaTeX排版系统和Exam文档类制作与生成题库,利用LaTeX实现自动编号、一键生成试卷和参考答案,以及数学公式、图表等格式化处理,从而形成一整套题库管理与出卷系统.

Defensive Role of Plant Latex on Insect Pests’ Suppression: A Critical Review

Over 350 million years have passed since the documentation of the first interaction between plants and insects. Numerous plant defense qualities and associated counter-adaptive features have developed as a result of these interactions between insects and plants. These characteristics might be either morphological or biological in nature. One of the most significant and useful biochemical characteristics in plants is latex. Latex has a sticky property due to presence of secondary metabolites in it, which aids in entangling or sealing the mouthparts of small insects. These metabolites also chemically interact with the insects interfering with crucial bodily processes. Plant latex has amazing properties that help protect plants from insects and inhibit them in general. It may be possible to control insect pests in a natural, secure, and long-lasting manner by correctly identifying plant latex with strong insecticidal properties and developing formulations of plant latex.

Effect of Ficus benghalensis Latex Based Combinatorial Formulations on Various Bio-Molecules in Indian White Termite Odontotermes obesus

In present investigation, various bioassays were conducted to evaluate the alteration in levels of certain biomolecules, such as glycogen, protein, amino acid, DNA, RNA and lipids. For this purpose, worker termites were treated with sub-lethal dose 40% and 80% of 24 hrs LD50 values and observations were taken at 4 hrs interval up to 24 hrs. Crude latex and its combinatorial mixtures, like S-MLT-A, B-MLT-A, C-MLT-A, CU-MLT-A, AQ-MLT significantly altered level of bio-molecules in Odontotermes obesus. This effect was found time and dose dependent. Reduction or increase in biomolecules was calculated by using corresponding control. Maximum decrease in glycogen level was observed at 16 h when termites were treated with 80% of LD50 of Ficus benghalensis aqueous extract i.e. 56.88% at 16 h of treatment. A similar dose caused very slight decrease in lipid contents at 4 h of treatment but it was found further significantly (p > 0.05) decreased in other successive treatments. 40% and 80% of LD50 of C-MLT-B mixture caused significant (p > 0.05) decrease in DNA and RNA level at 16 h treatment. The level of DNA and RNA level was recorded 83.90%, 90.18% and 85.42% and 74.05% respectively. Similarly, total proteins were also found to be decreased with 40% and 80% of LD50 of C-MLT-B mixture i.e. 71.47% and 66.45% respectively. All these alterations found in levels of various bio-molecules confirm the action of latex ingredients on worker termites that was antifeedant or deterrent types. These ingredients can be used to control not only termites but also other phytophagous insects in a sustainable and eco-friendly way.

Comprehensive treatment of latex wastewater and resource utilization of concentrated liquid

Latex wastewater is a kind of refractory organic wastewater containing high concentrations of organics and ammonia nitrogen.In this work,the combined process of forward osmosis(FO)and reverse osmosis(RO)was designed to treat the latex wastewater in the whole process,achieving the water recovery rate of 99%and basically no waste discharge after the catalytic oxidation process.The turbidity of the latex wastewater was decreased to below 1 NTU by microfiltration pretreatment,and then using MgCl_2 worked as the draw solution for FO process to treat the latex wastewater.Different operation conditions including adding acid or scale inhibitor as the pretreatment methods were conducted to improve the treatment performance of the combined process.After the treatment of the whole process,the concentration of COD was less than 20 mg·L^(-1),the concentration of NH_3-N was less than 10 mg·L^(-1),and the concentration of TP was less than 0.5 mg·L^(-1)for the treated latex wastewater.The water quality met standards of industrial water reuse after the complete analysis of the treated latex wastewater,meanwhile,useful substances of L-Quebrachitol(L-Q)were successfully extracted from the concentrated solution.Therefore,the combined process of FO and RO could realize the efficient treatment and reuse of latex wastewater,which provided with some important guidance on the industrial application.

Mechanical Characterization of Rubber Latex-Based Carpets (Hevea bresiliensis): Influence of Rubber Latex Content and Fiber Fabrics (Cotton and Mosquito Nets) on Wear Resistance of Rubber Latex-Based Carpets

This work focuses on the development of carpets from sand, fabrics of cotton fiber and mosquito nets and rubber latex. Following a study on the choice of the best formulations, the quantity of rubber latex used for shaping varies between 14% and 18% (latex/sand + latex ratio) for the carpet with the fabric of mosquito nets and between 16% and 18% for the one made with the fabric of cotton fiber. Thus, with a mixture of sand, fiber fabrics (cotton and mosquito nets) and rubber latex, carpets were developed. In addition, the wear test carried out on these samples indicates that it is possible to produce carpets with the new material made of rubber sand and latex: SABLATEX At room temperature. Following the characterization test, it resorts to only 16% latex with cotton fiber fabric, allowing to have carpets with good mechanical characteristics.

胶乳增强免疫比浊法NSE诊断试剂盒性能验证及临床应用

目的对胶乳增强免疫比浊神经元特异性烯醇化酶(neuron-specific enolase,NSE)试剂盒进行性能验证。方法按照CNAS-GL037:2019《临床化学定量检验程序性能验证指南》、WS/T492-2016《临床检测定量测定项目精密度与正确度性能验证》并结合试验工作,重新设计了检验方法,在贝克曼库尔特AU5800全自动生化分析对北京九强金斯尔NSE胶乳增强免疫比浊法试剂盒的正确度、精密度、线性范围、可报告范围和生物参考区间等性能进行验证和评估,并与对应罗氏电化学发光法试剂盒进行方法学比对。测试结果与厂家所给出的产品分析性能以及美国国家卫生委员会临床检测中心(National Center for Clinical Laboratories,NCCL)的相关指标进行了对比。结果5个水平的正确度偏倚分别为1.74%、-1.42%、-0.88%、-3.09%和-0.90%;2个水平的批内及批间精密度的变异系数(coefficient of variation,CV)分别为1.85%和0.88%(判断标准CV<7.5%),4.99%和3.34%(判断标准CV<10%);线性范围(3.5~148.1ng/mL)验证回归系数a值为0.9894,R2=0.9978;最大稀释倍数为8倍,临床可报告上限为1165.2ng/mL;厂家提供的生物参考区间为0~16.3ng/L,符合率R为100%,各性能均通过验证。此外,与罗氏电化学发光试剂盒进行方法学比对,其相关性分析结果为:两种方法的相关性(R2=0.989)、一致性(CCC=0.984)均较好,在临床判定效果上同Roche的电化学发光试剂盒相比,免疫增强比浊方法阳性符合率为95.74%,阴性符合率为96.23%,两者测定值接近,相关系数达0.9894。结论基于全自动生化分析平台测定的NSE胶乳增强免疫比浊试剂盒,各性能均可以较好地满足临床使用要求,且与电化学发光法检测结果一致性较好,有望进一步推进NSE国产体外诊断试剂盒的临床应用。

改性干粉型聚合物水泥砂浆试验研究

本文研究两种不同的可再分散乳胶粉(醋酸乙烯-乙烯共聚物和醋酸乙烯/叔碳酸乙烯酯共聚物)对干粉型聚合物水泥砂浆力学性能、粘结强度、吸水率、干燥收缩的性能影响。结果表明,可再分散乳胶粉的掺量、类型对聚合物水泥砂浆的性能影响较大,力学性能较普通水泥砂浆有明显的提升和改善。可再分散乳胶粉的加入虽然降低了砂浆的抗压强度,但显著提高了抗折强度和折压比,改善了砂浆的柔韧性和抗裂能力;砂浆的干燥收缩、粘结强度和吸水率等性能均有较为明显的改善。

动态光散射测量仪粒度标准物质的研制

【目的】解决国内尚缺动态光散射测量法专用粒度标准物质的问题。【方法】采用微乳液聚合法合成标称粒径为40、80 nm的态光散射粒度标准物质,标准物质编号分别是QBW12001和GBW12011b;采用动态光散射多家定值法测定2种粒度标准物质的散射光强调和平均粒径,定值结果溯源至动态光散射法(ISO 22412:2017)。【结果】合成的2种粒度标准物质均匀且稳定,散射光强调和平均粒径分别为(40.0±0.5)、(80±2)nm。【结论】不同厂家生产的激光粒度仪测的散射光强度调和平均粒径一致性最好;散射光强度平均粒径一致性较好;体积平均粒径一致性较差;颗粒数目平均粒径一致性最差。

搅拌工艺对高掺量丁苯乳液改性硫铝酸盐水泥性能的影响

研究了搅拌速度与搅拌时间对高掺量丁苯乳液改性硫铝酸盐水泥砂浆的匀质性、含气量、流变性能、早期强度等宏观性能的影响,采用TGA、BET等微观手段研究了硬化砂浆的水化程度和孔隙特征。结果表明:延长搅拌时间、提高搅拌速率均可改善砂浆的匀质性和力学强度。但以176 r/min搅拌时,延长搅拌时间会提高新拌砂浆含气量,增大硬化砂浆“凝胶孔”含量,抑制水泥前1 h的水化。以108 r/min搅拌时,延长搅拌时间则促进水泥前1 h的水化。延长搅拌时间和提升搅拌速率阻碍砂浆絮凝,破坏水泥颗粒桥接,显著降低结构构筑速率。延长搅拌时间,砂浆屈服应力和塑性黏度降低。优化搅拌工艺,有助于为充填层修补砂浆的搅拌规范制定提供重要参数。

良性前列腺增生患者临床参数间的相关性分析及方法学评价

目的探讨良性前列腺增生患者的前列腺体积、患者年龄、血清总前列腺特异性抗原(TPSA)、血清游离前列腺特异性抗原(FPSA)、前列腺特异性抗原密度(PSAD)的相互关系,同时通过患者年龄预测前列腺体积(PV)大小的准确性。研究胶乳免疫比浊法检测血清TPSA、FPSA水平与电化学发光法比较的可行性和实用性。方法收集172例患者的临床资料进行统计学分析,总结患者年龄、前列腺体积、TPSA、FPSA及PSAD的相关性,并使用受试者特征ROC曲线分析血清TPSA、FPSA预测前列腺体积的准确性。用两种方法同时检测血清TPSA和FPSA,比较其相关性、偏差和阴阳性符合率。结果患者TPSA,FPSA,PV随年龄增高而增大(r=0.318、0.325、0.511,P均<0.01),TPSA和FPSA也随PV增大而增高(r=0.279、0.368,P均<0.01)。与TPSA相比,FPSA与患者年龄、PV的相关性更强。TPSA水平<4ng/mL时,对于前列腺体积30~49mL、50~79mL和>80mL 3组,TPSA预测的AUC为0.621、0.708、0.913,最佳临界值分0.7、1.98、2.37ng/mL;FPSA预测的AUC为0.682、0.711、0.832,最佳临界值为0.37、0.56、0.81ng/mL。电化学发光法与胶乳免疫比浊法检测TPSA、FPSA相关性良好(r=0.986、0.975,P均<0.01);两种方法检测TPSA结果和FPSA结果的一致性良好;二者的阳性符合率、阴性符合率和总符合率分别为98.63%和90.54%、93.94%和96.94%、96.51%和94.18%,Kappa值为0.930、0.850(P均<0.01)。其精密度,线性范围和参考区间验证均符合标准。结论患者年龄、前列腺体积、TPSA水平、FPSA水平之间有显著的相关关系。血清TPSA和FPSA作为临床上独立预测PV的简便可行的因子具有较高准确性,其中FPSA预测的准确性更高。胶乳免疫比浊法与电化学发光法比较一致性较好,胶乳免疫比浊法可以作为检测TPSA和FPSA水平的推荐方法。

防灭火喷涂材料黏附及封堵性能试验研究

为改善煤矿井下巷道喷涂防灭火材料黏附性差,易开裂、易脱落及封堵效果差等问题,研制了一种以粉煤灰为骨料,普通硅酸盐水泥、硫铝酸盐水泥和石膏为基料,可再分散乳胶粉(VAE)为外加剂的防灭火喷涂材料。通过单轴抗压强度实验、煤岩多相多场真三轴动态渗流实验以及扫描电镜实验等,研究了VAE对喷涂材料的黏附性能、胶结性能、力学性能、封堵性能的影响。结果表明,加入VAE可以促进水化产物中丝状黏结桥的形成,实现黏结桥与水化产物的铆接、桥连,构成一个致密的网络结构。这不仅可以提升喷涂材料的抗开裂能力,同时增强了材料与煤结合后的黏附性能、胶结性能以及封堵性能。加入1%VAE的喷涂材料能够充分包裹住煤体,在煤体表面形成致密的涂层,有效隔绝空气与煤体接触,从而预防煤自燃,研发的材料对防治巷道顶部煤自燃具有一定作用。

预制构件用水泥基修补砂浆的制备及应用研究

为修补预制构件施工过程中缺角、裂缝等缺陷,以硅酸盐水泥、硫铝酸盐水泥和半水石膏作为胶凝体系,掺加适量减水剂、乳胶粉和其他助剂,制备一种凝结时间短、早期强度高的水泥基修补砂浆,并对其性能进行研究。结果表明,掺加减水剂可以提高修补砂浆的抗压强度和流动度,掺加乳胶粉会延长砂浆的凝结时间,降低抗压强度,同时砂浆流动度则随乳胶粉掺量的增加先增大后减小。减水剂掺量以0.20%为宜,乳胶粉掺量以5.0%为宜,此时修补砂浆的初、终凝时间分别为15.8、22.4 min,7、28 d抗压强度分别为32.2、55.1 MPa,流动度为212 mm。