Electrons Transfer Between Mercaptoacetic Acid and ZnO Nanocrystal Thin Film

ZnO nanoorystals thin film were prepared by means of the self-assembly mothed. The complex films of mercaptoacetic acid(MPA) and ZnO nanocrystals(ZNCs) were prepared by means of the self-assembly technique. The interaction between the MPA and ZnO within the MPA and ZnO nanocrystal thin film decreases the photoluminescence intensity of the ZnO. The interaction was manifested by the X-ray photoelectron spectra. The intensity change of the photoluminescence of the ZnO is discussed on the basis of taking into account the process of electron transfer on the interface between the ZnO and MPA. The electron transfer of ZnO depends on the distance between the ZnO and MPA.

Flavonoids and Amino Acids Analysis of the Fruits of Cornus mas L. Introduced in Uzbekistan

Cornelian cherry is used in the food and pharmaceutical industry as an ornament, in traditional medicine, and in the manufacture of household items. It is widely used in medicine for the prevention and treatment of many diseases. Therefore, it is important to research the chemical composition of these species. In the article, based on our research, the analysis of the quantitative calculation of flavonoids and amino acids of the fruits of the “Elegant” and “Svetlyachok” cherry varieties was carried out. It was found that the amount of amino acids in the fruits of Cornus mas L., introduced in Uzbekistan, is higher in the variety “Svetlyachok” 2.643235 mg/g. In “Elegant” variety it was 1.794235 mg/g. The amount of 4 different flavonoids in the fruit was also determined. It has been established that the Elegant variety has a high concentration of lutein and rutin, and the svetlyachok has a high concentration of apigenin and quercetin.

Determination of Surface pKa of Pure Mercaptoacetic Acid and 2-Mercaptobenzothiazole Mixed Monolayers by Impedance Titration

Interfacial proton transfer reactions of pure mercaptoacetic acid (MA) and 2-mercaptobenzothiazole (Mbz) mixed self-assembled monolayers (SAMs) have been studied using a.c. impedance titration method. The charge-transfer resistance (Rct,) is measured with the monolayer composition and the ionic strength of pH solution. The surface pKa can be obtained by the plots of Rct and pH, the reasons of shifts of surface pKa are also explained.

Synthesis and DNA Cleavage Studies of 2,6-Dimethoxyhydroquinone-3-Mercaptoacetic Acid Conjugates

In an effort to investigate the use of short peptide chains as carriers of new anti-tumor agents, we synthesized four tripeptide-cytotoxic agent conjugates: DMQ-MA-Lys(DMQ-MA)-Phe -Arg-Ome, DMQ-MA-Lys(DMQ-MA)-Ile-Arg-Ome, DMQ-MA-Lys(DMQ-MA)-Val-Arg-Ome, DMQ-MA-Lys(DMQ-MA)-Lys(Cbz)-Arg-Ome. The cytotoxic agent conjugated to the N-terminal and the xi -amino group of Lysine of the tripeptide is 2,6-dimethoxyhydroquinone-3-mercaptoacetic acid (DMQ-MA). The tripeptides were synthesized by coupling protected amino acid residues according to Pfp/DCC methods (Pfp: pentafluorophenol, DCC:N,N'-dicyclohexyl-carbodiimide) in solution. Agarose gel electrophoresis showed that these compounds can cleave supercoiled DNA into open-circular form in drug concentration as low as 4-50 mu M without H2O2 and UV irradiation. Further studies on their cytotoxicity for these conjugates are ongoing.

Synthesis, and Investigation of the Reactive Oxygen Species of a Novel Cyclicpeptide-2,6-dimethoxyhydroquinone-3- mercaptoacetic Acid Conjugate

In this paper, we report the synthesis of a potential anti-cancer agent: Cyclo[Val-Lys(DMQ-MA)-Gaba]. The cytotoxic agent conjugated to the N-terminal and the xi -amino group of lysine of the tripeptide is 2,6-dimethoxyhydroquinone-3-mercaptoacetic acid (DMQ-MA). By employing the rhodamine B degradation method and ESR spectra, we testify the reactive oxygen species - hydroxyl radicals produced by the drug.

Investigation of the Reaction Mechanism of Itaconic Acid/Maleic Acid Copolymer System and Cotton Cellulose

The reaction mechanism of IA/MA copolymer system andcotton cellulose is conjectured and verified, the two keysteps, such as the formation of cyclic anhydride interme-diates and the building of ester crosslinklng, and the ef-fect of sodium hypophosphite are especially emphasized,by FT - IR spectroscopy and acid- base titration anal-yses. The experiments reveal that carboxylic acids main.ly change to cyclic anhydride in the pre - drying step andSodium Hypophosphite (SHP) has effect on it, but mostester - crosslinkages are built in the curing step and SHPhas effects on both anhydride formation and ester -crosslinking formation.

The Effect of Methacrylic Acid and Maleic Acid on the Isothermal Kinetics of Acrylic Acid Crosslinking Co-polymerization under Conventional and Microwave heating

The kinetics of free-radical crosslinking co-polymerization(FRCCP)of acrylic acid(AA)with both methacrylic acid(MA)(PAMA hydrogel)and maleic acid(MAL)(PAMAL hydrogel)was investigated under the conditions of isothermal conventional heating(CH)and under the conditions of microwave heating(MWH)with controlled cooling.The kinetics curves of FRCCP of PAMA and PAMAL hydrogels under the conditions of CH are described with the kinetics model of second order chemical reaction,whereas the kinetics curves under the conditions of CH are described with the kinetics model of Polany-Winger.It is proved that MWH leads to the changes in the rate of FRCCP and to the changes in the values of the kinetic parameters activation energy(Ea)and pre-exponential factor(lnA).It was found the existence of relationship between the values of the kinetic parameters calculated for MWH and CH for PAMA and PAMAL hydrogel synthesis process,which is well-known as compensation effect.The effect of MWH on the kinetics of FRCCP for PAMA and PAMAL hydrogel formation were explained by applying the model of activation by selective energy transfer(SET).The changes in kinetics model,rate of FRCCP and kinetics parameters,caused with the MWH can found wide application in designing novel technologies for obtaining polymers and for synthesis of polymers with novel physico-chemical properties.The suggested mechanism of activation for polymerisation under the conditions of MWH also enables development of novel reaction systems and technologies for polymers productions.

Evaluation of Disk Potentiation Test (DPT) and Double Disk Synergy Test (DDST) for The Detection of Metallo-β-Lactamases (MBLs) in Clinical Isolates of Bangladesh

Objective: Increasing the emergence of Metallo-β-lactamase (MBL) producing gram-negative bacteria and their dexterous horizontal transmission demands rapid and accurate detection. This study was conducted to determine a suitable method to promptly detect MBL-producing gram-negative bacteria. Methods: A total of 103 gram-negative bacteria were identified from various clinical samples at a tertiary care hospital in Dhaka city. MBL producers were detected by two phenotypic methods, the Disk Potentiation Test (DPT) and the Double Disk Synergy Test (DDST) based on β-lactam chelator combinations where EDTA/SMA has been used as an inhibitor and Imipenem, Ceftazidime as substrates. Results: 103 isolates which were identified as Escherichia coli spp, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Proteus spp, Providencia spp were found to be multidrug-resistant in antibiogram test. Isolates showed complete resistance (100%) to Imipenem, Meropenem, and Amoxiclav. The highest carbapenem-resistant etiological agents were Acinetobacter spp 40 (38.8%) followed by Pseudomonas spp 27 (26.2%), Klebsiella spp 26 (25.2%), Escherichia coli 8 (7.8%), Proteus spp 1 (1%) and Providencia spp 1 (1%). DPT method detected significantly (p = 0.000009) a higher number of MBL-producers (Imipenem with 0.5 M EDTA n = 61, 59.2% & Ceftazidime with 0.5 M EDTA n = 56, 54.4%) compared to the DDST method (Imipenem -0.5 M EDTA n = 43, 41.7%, Imipenem – SMA n = 38, 36.9% & Ceftazidime -0.5 M EDTA n = 15, 14.6%). Conclusion: Pieces of evidence suggest that DPT is a more sensitive method than DDST and could be recommended for identifying MBL-producing bacteria in Bangladeshi hospitals for the proper management of patients, to reduce time constraints and treatment costs.

高分子重金属絮凝剂MAPEI的制备及性能研究

通过酰胺化反应将重金属络合剂巯基乙酸(TGA)接入高分子絮凝剂聚乙烯亚胺(PEI)的分子链中,合成了新型高分子重金属絮凝剂巯基乙酰聚乙烯亚胺(MAPEI),以达到用同一种絮凝剂既能除重金属又能除浊的目的.实验结果表明:①该絮凝剂对Cu2+有很好的捕集功能,Cu2+的最高去除率可达95%以上;②pH值对MAPEI除Cu2+、去浊的效果有一定的影响但影响不大,pH值低时除浊效果较好,pH值较高时除Cu2+效果较好;③当Cu2+和致浊物质共存时,会互相促进彼此的去除;④废水中Ca2+的存在会促进Cu2+的去除,Fe3+的存在会抑制Cu2+的去除.

多元羧酸与木材酯化反应的固体核磁共振谱CPMAS^(13)CNMR的表征

本研究要用以多元羧酸为酯化剂 ,以无机盐为催化剂的交联体系。这一体系是新型的、水溶的、无毒害、无污染的非甲醛系试剂并联体系。本文采用固体核磁共振谱CP MAS1 3 CNMR ,测定木材主要组分酯化反应的CP MAS1 3 CNMR波谱 ,归属主要谱线 ,分析了多元羧酸与木材交联反应过程中主要组分的化学结构变化。结果表明 :酯化反应后 ,羧基碳的比率增加 ;芳香族碳和羟基碳的比率减少 ;烷基碳的变化随着羧基碳的变化而改变。

MA-AA-AM三元共聚物的阻垢性能

以马来酸酐(MA)、丙烯酸(AA)和丙烯酰胺(AM)为原料,在水相中聚合制备三元共聚物PMAA,从因素效应方面综合研究其阻垢性能。实验表明,PMAA对温度有较宽的适应范围,在中酸性和弱碱性条件下能较好地发挥阻垢性能,在高浓缩倍数下亦有良好的阻垢效果。在水样pH=7,温度为80℃,阻垢剂PMAA质量浓度为6mg/L时,恒温10 h,对碳酸钙阻垢率为97.38%,对磷酸钙阻垢率为85.69%;PMAA质量浓度为12 mg/L,对碳酸钙阻垢率可达100%,对磷酸钙阻垢率亦能达96.5%以上。

MA-AA-MAS三元共聚物的制备及其阻垢性能研究

以水为溶剂,过硫酸钾为引发剂,马来酸酐(MA)、丙烯酸(AA)和甲代烯丙基磺酸钠(MAS)为单体合成了三元共聚物.探讨了该共聚物转化率、平均分子质量、阻垢分散效果与单体配比、引发剂用量、反应温度、反应时间之间的关系.结果表明,当单体MA,AA,MAS物质的量比为3.0∶1.0∶0.6,引发剂质量分数为单体总量的14%,反应温度应控制在90℃,反应时间为4 h时,所制得的共聚物性能最佳,单体转化率为90.1%,对CaCO3和Ca3(PO4)2的阻垢率分别达到98.2%和92.1%.

MA/HPA/IPPA膦酰基羧酸三元共聚物阻垢分散性能的研究

考察了合成的马来酸酐(MA)/丙烯酸羟丙酯(HPA)/异丙烯膦酸(IPPA)新型膦酰基羧酸共聚物对碳酸钙、硫酸钙和磷酸钙垢的阻垢性能,探讨了MA/HPA/IPPA膦酰基羧酸共聚物稳定锌离子和分散氧化铁能力。结果表明,MA/HPA/IPPA膦酰基羧酸三元共聚物不仅具有优异的抑制钙盐沉积的性能,而且具有良好的稳定金属锌离子和分散氧化铁颗粒能力,是一种综合性能较好的多功能水质稳定剂。

VAc/MA/AA三元无皂乳液共聚的研究

以过硫酸钾(KPS)为引发剂,对VAc/MA/AA三元无皂乳液共聚进行了研究。探讨了引发剂用量、功能单体用量(AA)对乳液稳定性、胶乳粒子粒径、粒径分布及胶乳粘度、粘接强度等性质的影响。结果表明: 引发剂用量小于单体总质量的0．7％时,随着KPS用量的增加,胶乳粒子粒径减小,粒径分布变窄;引发剂用量大于单体总质量的0．7％时,随着KPS用量的增加,胶乳粒径及分布都增大,KPS用量为单体总质量的6％时,单分散性好;共聚乳液的粒径随AA用量的增加而增加,粒径分布则随AA用量的增加而减小,乳液粘度随AA用量增大而降低,而粘接强度随AA用量增大而增加,耐水性下降。

PESA和MA/AA分别萃取污泥中汞的比较研究

以汞污泥为材料,分别用聚环氧琥珀酸(PESA)和丙烯酸-马来酸酐共聚物(MA/AA)作为萃取剂,研究了PESA和MA/AA在不同pH、萃取剂浓度、搅拌时间和土液比下对汞(Hg)的萃取效果。实验结果表明,PESA对污泥中Hg的萃取效果优于MA/AA。在萃取体系pH分别为6和9,土液比分别为1∶250和1∶300,萃取剂浓度均为30 mg/mL、搅拌时间均为60 min时,PESA和MA/AA对泥土中汞的萃取率分别为63%和28%。用PESA萃取后的污泥达到《危险废物鉴别标准·浸出毒性鉴别》堆放标准。PESA中不含有氮、磷等元素,不会引起水体的富营养化及环境污染,是一种环境友好型水溶性聚合物。

AMPS／AA／MA三元共聚物的合成及降粘性能

合成了ＡＭＰＳ／ＡＡ／ＭＡ三元共聚物，研究了合成反应中ＭＡ用量对淡水泥浆、含盐和含钙泥浆及强碱性泥浆性能的影响。研究结果表明，ＭＡ用量为６０％（摩尔）的ＡＭＰＳ／ＡＡ／ＭＡ三元共聚物的抗钙性能明显优于ＡＭＰＳ／ＡＡ二元共聚物；ＭＡ用量为３０％（摩尔）的三元共聚物的抗温抗盐性能与ＡＭＰＳ／ＡＡ二元共聚物相当。

AM/AA/MA三元共聚物降失水剂PL-1的室内研究

以氧化还原体系为引发剂,在40±2℃和氮气保护的条件下用丙烯酰胺、丙烯酸、马来酸酐三种单体进行水溶液共聚,合成了 PL-1水泥浆降失水剂。考察了 PL-1对水泥浆失水量、流变性、稠化时间等性能的影响。结果表明,PL-1的合成条件简便,具有良好的耐温和抗剪切性,对水泥浆有很强的降滤失作用及良好的分散作用。

IR.MAS NMR法研究富硅超稳镨氢Y沸石

制备了NH_4Y、USY、PrHY、USPrHY、F8Y及FSPrHY催化剂,测定其组成和物性.于红外光谱装置上比较了上述催化剂羟基峰的异同,通过对吡啶的吸脱附测定了诸催化剂的酸强度.B 酸强度顺序为:FSPrHY>FSY>USPrHY>USY>PrHY>NH_4Y.^(29)Sit MAS NMR 谱表明,在USPrHY 及FSPrHY 的Si(0Al)%甚多于PrHY 和NH_4Y 中的Si(0Al)%.IR、^(29)Sj MAS NMR 及活性测试等结果说明:沸石中0NNN 铝位的存在,是达到强酸性的必要条件.高价稀土阳离子形成(?)及Pr(OH)^(2+)抵消了方钠石笼中AlO_4^-上的电荷,增强了剩余铝位上羟基酸强度;且从骨架羟基上吸引电子,因而使质子酸性更强,从而提高了裂解、岐化、脱烷基活性.

基于马斯定律优化VRLA电池快充参数

分析阀控式铅酸(VRLA)电池充电时遵循的马斯定律,提出在充电过程中加入负脉冲放电去极化,减少过电势,既能提高电池初始充电可接受电流,又能提高充电可接受率的脉冲快速充电方法。制作用于12 V/20 Ah以下VRLA电池的脉冲快速充电电路,通过多次充电实验,确定具体的充电阶段和优化的充电参数。VRLA电池脉冲快速充电电路通过第一阶段较大电流恒流充电,在较短的时间内尽量充入较多的电量,第二阶段优化充电参数的脉冲循环快速充电,可减小电池的浓差极化,充电效率大为提高,从而达到快速、无损充电的目的。

PLA/SBS/S-MA共聚物共混体系的结晶行为

以苯乙烯–丙烯酸甲酯无规共聚物(S-MA)为增容剂,采用熔融共混法制备了聚苯乙烯–聚丁二烯–聚苯乙烯三嵌段共聚物(SBS)填充改性聚乳酸(PLA)共混体系。使用扫描电镜(SEM)、差示扫描量热仪(DSC)、偏光显微镜(POM)研究了增容剂对PLA/SBS共混体系中分散相形貌、基体结晶行为、球晶的成核与生长等的影响。SEM结果表明,在PLA/SBS中加入S-MA后,有效地减小了分散相尺寸,显著地提高了PLA和SBS的界面相容性;DSC和POM结果显示,SBS对PLA的结晶具有异相成核作用和增塑效应,在不同降温速率过程中,共混物中PLA的结晶度均达到了纯PLA的5倍以上;加入S-MA后,其提高了共混物的相容性,共混物中PLA的结晶度有一定程度下降,但是仍显著高于纯PLA。上述研究结果证明了S-MA能对PLA/SBS共混体系进行有效的增容,在实现了对PLA基体进行增韧的同时,提高了结晶度。