Adsorption of Silver Nitrate by Cotton Fabrics Containing Polyethylene Sulfide

The adsorption of silver nitrate from aqueous solution by polyethylene sulfide-containing cotton fabrics was investigated. The adsorption could be described by a Freundlich-type isotherm with n= 1. δH^os was calculated from adsorption isotherms and from the equilibrium constant of complex formation and similar results of-5.6 and -5.4 kcal/mole were obtained, respectively. At low silver nitrate concentrations most of the silver nitrate present in solution could be adsorbed. It was found that adsorption by polyethylene sulfide in the fabric was much higher than that of homo-polyethylene sulfide.     

巯基改性棉纤维化学镀银导电布的研究

应用正交试验法研究巯基改性棉纤维表面化学镀银的特性,测定各因素对表面方阻和增重率的影响,得出制备化学镀银棉织物的最佳工艺：巯基硅烷浓度1%、改性时间120 min、改性液浴比1:60、硝酸银用量3.5 g、葡萄糖用量45 g、化学镀温度50 ℃、化学镀时间60 min.SEM和XRD分析表明巯基改性棉织物镀层均匀致密,具有良好的电磁屏蔽性.采用透明胶带法测试证实,该镀层结合牢固.     

Investigation on the Enhancement of Antimicrobial Activity of Neem Leaf Extract Treated Cotton Fabric Using Air and Oxygen DC Plasma

The enhancement of hydrophilicity of DC air and oxygen plasma treated cotton fabric and its effect on the antimicrobial efficacy when treated with neem leaf extract is reported in this paper. The axial and radial ion density distribution between the electrodes was studied using Langmuir probe to place the fabric between the electrodes for effective plasma treatment. The effect of system parameters viz., process gas pressure, DC power density and plasma exposure time on the hydrophilicity and hence the antimicrobial efficacy after the neem leaf extract treatment was analysed and optimised. The functional group present in the cellulose units of the cotton fabric before and after plasma treatment was identified and estimated using standard tests and analysed using ATR–FTIR spectra. The surface morphology of untreated and plasma treated cotton fabric was analyzed with the help of SEM micrograph. The mean pore diameter of the fabric matrix was calculated and air permeability was measured before and after plasma treatment to account for the improved capillarity due to plasma treatment. The formation of functional groups with increased polarity and improved capillary action of the plasma treated fabric enhances its hydrophilicity which in turn improves the sorption of neem leaf extract and hence the antimicrobial activity.     

基于三维纳米银修饰电极的硝酸根微型传感芯片研究

研制一种基于金叉指微电极阵列(IDA)的电流型硝酸根离子(NO-3)微传感电极芯片.基于微机电系统(Micro-Electro-Mechanical Systems,MEMS)工艺制备金IDA微电极,通过电化学沉积技术在IDA微电极表面修饰三维枝状结构纳米银敏感膜,利用敏感膜对硝酸根离子良好的电催化还原性能,采用脉冲方波伏安(SWV)电化学测量方法,实现对硝酸根离子在25～1000μmol/L浓度范围内的快速检测,灵敏度达9.5 nA/(μmol/L),线性度为99.98%,检测下限为10μmol/L.考察水体中常见的NO-2,F-,3PO 4-,SO 42-,2CO3-,NH+4,Na+和K+等离子对该传感芯片的干扰性能,传感芯片表现出较好的抗干扰性能.制备的三维枝状结构纳米银修饰IDA微电极可实现水环境(pH 5.0～9.0)中NO-3的电化学检测,对应用于自然水环境中硝酸根离子的现场检测具有积极意义.     

四硫富瓦烯衍生物修饰的银溶胶

四硫富瓦烯衍生物修饰的银溶胶;银溶胶;纳米粒子;四硫富瓦烯;氧化还原;表面修饰     

Antimicrobial Activity and Physical Characterization of Silver Nanoparticles Green Synthesized Using Nitrate Reductase from Fusarium oxysporum

Nanostructures from natural sources have received major attention due to wide array of biological activities and less toxicity for humans, animals, and the environment. In the present study, silver nanoparticles were successfully synthesized using a fungal nitrate reductase, and their biological activity was assessed against human pathogenic fungi and bacteria. The enzyme was isolated from Fusarium oxysporum IRAN 31C after culturing on malt extract-glucose-yeast extract-peptone (MGYP) medium. The enzyme was purified by a combination of ultrafiltration and ion exchange chromatography on DEAE Sephadex and its molecular weight was estimated by gel filtration on Sephacryl S-300. The purified enzyme had a maximum yield of 50.84 % with a final purification of 70 folds. With a molecular weight of 214 KDa, it is composed of three subunits of 125, 60, and 25 KDa. The purified enzyme was successfully used for synthesis of silver nanoparticles in a way dependent upon NADPH using gelatin as a capping agent. The synthesized silver nanoparticles were characterized by X-ray diffraction, dynamic light scattering spectroscopy, and transmission and scanning electron microscopy. These stable nonaggregating nanoparticles were spherical in shape with an average size of 50 nm and a zeta potential of ?34.3. Evaluation of the antimicrobial effects of synthesized nanoparticles by disk diffusion method showed strong growth inhibitory activity against all tested human pathogenic fungi and bacteria as evident from inhibition zones that ranged from 14 to 25 mm. Successful green synthesis of biologically active silver nanoparticles by a nitrate reductase from F. oxysporum in the present work not only reduces laborious downstream steps such as purification of nanoparticle from interfering cellular components, but also provides a constant source of safe biologically-active nanomaterials with potential application in agriculture and medicine.     

Model of the Negative DC Corona Plasma: Comparison to the Positive DC Corona Plasma

A numerical model of the negative DC corona plasma along a thin wire in dry air is presented. The electron number density and electric field are determined from solution of the one-dimensional coupled continuity equations of charge carriers and Maxwell's equation. The electron kinetic energy distribution is determined from the spatially homogeneous Boltzmann equation. A parametric study is conducted to examine the effects of linear current density (0.1–100 A per cm of wire length), wire radius (10–1000 m), and air temperature (293–800 K) on the distribution of electrons and the Townsend second ionization coefficient. The results are compared to those previously determined for the positive corona discharge. In the negative corona, energetic electrons are present beyond the ionization boundary and the number of electrons is an order of magnitude greater than in the positive corona. The number of electrons increases with increasing gas temperature. The electron energy distribution does not depend on discharge polarity.     

银掺杂改性蒙脱土修饰电极上对苯二酚的电化学行为与测定

利用十八烷基三甲基溴化铵(STAB)和银氨溶液制备了银掺杂改性蒙脱土,并用X射线衍射法、扫描电镜法和交流阻抗法对其进行表征.用循环伏安法(CV)研究了对苯二酚在银掺杂改性蒙脱土修饰电极上的电化学行为,测定了部分动力学参数.结果表明,对苯二酚在电极上的阳极过程受吸附-扩散混合控制,阴极过程受扩散控制,转移的电子数n和质子...     

Improvement on Hydrophilic and Hydrophobic Properties of Glass Surface Treated by Nonthermal Plasma Induced by Silent Corona Discharge

A fundamental study was conducted to investigate the improvement of the hydrophilic and hydrophobic properties of the glass surface using the atmospheric-pressure nonthermal plasma. The plasma was induced between the two parallel electrodes with a dielectric barrier using an AC 60Hz high voltage power supply. The objective is to demonstrate the possibility of the elimination of the windshield wiper from automobiles. Two approaches were undertaken for modifying the glass surface: one is hydrophilic approach using plasma alone and the other is hydrophobic approach using the combination of hydrophobic chemical and nonthermal plasma. The plasma application provided excellent hydrophilic properties (less than 4° of contact angle). However, the durability did not last for more than one day. The combination of hydrophobic Tri Alkoxy Silane (TAS) chemical coating and nonthermal plasma showed an excellent hydrophobic property and extended durability, more than five times more durable compared with TAS alone.     

Preparation of Antimicrobial Ultrafine Cellulose Acetate Fibers with Silver Nanoparticles

Summary: A feasible method for the preparation of antimicrobial ultrafine fibers with silver nanoparticles was developed by direct electrospinning of a cellulose acetate (CA) solution with small amounts of silver nitrate followed by photoreduction. Silver nanoparticles in ultrafine CA fibers were stabilized by interactions with carbonyl oxygen atoms in CA. Ultrafine CA fibers with silver nanoparticles showed very strong antimicrobial activity.

TEM image of an ultrafine CA fiber electrospun from 10 wt.‐% CA solution with 0.5 wt.‐% AgNO₃.     

利用废胶片制取硝酸银

医院用过的X光片每年都要处理一些,印刷厂照相制版用过的胶片有好多被丢弃进垃圾堆里。只要收集到上百克废胶片,对其进行回收所制得的硝酸银就够普通中学实验室用很长的时间。     

Kinetic Parameters of Silver Electrodeposition from Nitrate Melts

The system Ag/KNO₃–NaNO₃–AgNO₃is studied in an open bath in air by various experimental methods. The limiting diffusion currents of the silver electrodeposition are determined by a galvanodynamic method at various linear current sweep rates. The diffusion coefficient of Ag⁺ions in equimolar KNO₃–NaNO₃melt is determined by a potentiodynamic method at linear potential sweep. The exchange currents on a silver support are determined by the method of two current pulses.     

不同结构二元羧酸改性棉纤维铁配合物的制备和光催化性能

分别使用3种不同结构的二元羧酸[酒石酸(TA)、 苹果酸(MA)和丁二酸(SA)]对棉纤维改性引入羧基并与Fe ³⁺离子反应制备羧酸改性棉纤维铁配合物, 考察了二元羧酸结构和浓度对改性棉纤维的羧基含量(Q_COOH)及其铁配合物的铁配合量(Q_Fe)的影响. 研究了3种羧酸改性棉纤维铁配合物作为有机染料氧化降解反应和Cr(Ⅵ)还原反应光催化剂的性能. 结果表明, 改性棉纤维的Q_COOH值随羧酸浓度的增加而增加. 不含羟基的SA比2种羟基羧酸TA和MA能给棉纤维引入更多羧基, 而2种羟基羧酸改性棉纤维铁配合物则具有更高的Q_Fe值. 3种羧酸改性棉纤维铁配合物对染料氧化降解反应和Cr(Ⅵ)还原反应都表现出显著的光催化作用, 且随其Q_Fe和辐射光强度的提高而增强. TA改性棉纤维铁配合物比其它2种配合物具有更高的光催化活性. 3种配合物不但能将Cr(Ⅵ)还原为Cr(Ⅲ)离子, 而且还能将其部分吸附去除, MA改性棉纤维铁配合物具有较高的铬离子去除效率.     

Capsules with Silver Nanoparticle Enrichment Subdomains and Their Antimicrobial Properties

The fabrication of polyelectrolyte multilayer capsules with controllable submicron‐sized subdomains and the in situ synthesis of silver nanoparticles are reported. Because poly(acrylic acid) (PAA) is released from the shell of the capsules in the dissolution process of sacrificial cores, the remaining poly(4‐vinylpyridine) (PVP) forms subdomains of spheres with controllable sizes, which can be tuned by the number of PVP/PAA bilayers. This creates capsules with special surface morphology and enables the in situ synthesis of Ag nanoparticles within the PVP subdomains on the shell of capsules. In addition, the in‐situ formed Ag nanoparticles can be mostly released from PVP subdomains of capsules in pH 2.0 solution, whereas they are stable in neutral solution. These specially designed capsules containing Ag nanoparticles can be used as antimicrobial materials and potentially benefit remote drug release by laser activation.     

改性硝酸铵自敏化结构特征

对经复合表面活性剂处理的改性硝酸铵及普通硝酸铵晶体进行电镜扫描,孔径孔容分布,粒径分布,比表面积测定,抗吸湿结块性,差示量热分析以及爆炸性能的实验研究,结果表明,与普通硝酸铵相比,改性硝酸铵的晶形歧化,比表面积大,富含气孔,大部分的有效孔径座落在介孔范围,有较好的粒度级配,晶变热降低,且晶变点后移,具备自敏化结构特征,并且有良好的抗吸湿结块性,用它代替普通硝酸铵所制得的粉状工业炸药具有良好的物理性能和爆炸性能。     

菊苣酸在高效液相色谱测定过程中与流动相中银离子配位的探讨

菊苣酸是紫锥菊属植物中的一种水溶性酚酸类化合物.本研究对紫锥菊提取物中菊苣酸检测的条件是:流动相为V(乙腈)∶ V(去离子水)=38∶ 62(含0.8%冰醋酸和8 mmol/L AgNO3);色谱柱为Restek Pinnacle 11 C18柱(250 mm×4.6 mm, 5 μm);流速为0.5 mL/min;进样量为10 μL;检测波长为326 nm.实验发现,在流动相中添加AgNO3后可以明显改善菊苣酸测定效果,提高分离度,并有效除去其它杂质成分的干扰, r大于0.99;检出限为8～40 mg/L,此方法的相对标准偏差小于3.0%;平均回收率为98.5%,方法符合测试要求.AgNO3改善分离效果的原因可能为菊苣酸和Ag 之间存在一定的配位作用,改变了菊苣酸的性质,扩大了与杂质成分的结构差异,从而使测定更准确,同时用红外和紫外光谱辅助解释了可能的配位机理和配位点.     

银纳米粒子修饰银电极法测定酪氨酸

通过NaBH₄还原AgNO₃得到胶体银纳米粒子,制作了以该纳米粒子修饰的银电极。研究了银纳米粒子修饰银电极在电催化中的应用,并对相关机理进行了探讨。该修饰电极对醋酸具有电催化活性,但酪氨酸却对该催化信号有明显的抑制作用,因此建立了用胶体银纳米粒子修饰银电极在NaAc-HAc缓冲溶液中检测酪氨酸的方法,并讨论了最佳工作条件。结果表明：在pH = 5.5时,峰电流与酪氨酸的浓度在1.0×10_-8～1.0×10_-3mol L_-1 范围内呈良好的线性关系,检出限为4.2×10_-9 mol L_-1,线性回归方程为Ip (μA) = 7.64 pC – 15.69 ( R = 99.73% )。用该方法检测氨基酸注射液中酪氨酸的含量,加标回收率在95.2%~107.8%之间。     

吸光光度法测定硝酸银中微量铜

硝酸银制成后测定杂质含量是鉴定纯度的一个重要环节。杂质铜的含量多少直接影响到硝酸银的纯度。本文研究了 0 .1～ 0 .3ｍｏｌ·Ｌ- 1ＫＯＨ介质中 ,用ＫＩＯ4 作为显色剂 ,采用巯基棉分离 ,吸光光度法测定了硝酸银中微量铜 ,结果满意。1　试验部分1.1　主要仪器与试剂756ＭＣ紫外可见分光光度计 (上海第三分析仪器厂 )Ｃｕ2 +标准溶液 :称取ＣｕＳＯ4 ·Ｈ2 Ｏ 1.96 4 4 ｇ于烧杯中 ,加水溶解后 ,再加几滴硫酸 ,移入 50 0ｍｌ容量瓶 ,稀至刻度 ,配成 1ｍｇ·ｍｌ- 1储备液。逐级稀释成10 μｇ·ｍｌ- 1工作液。ＫＩＯ4 溶液 :称取ＫＩＯ4…     

Determination of Nitrate and Nitrite Ions in Human Plasma by Ion Exchange-High Performance Liquid Chromatography

Abstract

Acetonitrile precipitation of plasma samples followed by injection of supernatant onto a reverse phase precolumn coupled to an anion exchange column allowed ultraviolet detection (214 nm) of eluting nitrate and nitrite ions. Sensitivity in plasma is about 0.01 mM for both ions and linearity is excellent from 0.02 to 1.0 mM. Nitrite accuracy assessed by diazotization coupling was good. Reproducibility studies demonstrated withinrun coefficients of variation of < 4%. Interferences were few. Random endogenous serum nitrate concentrations (0.03–0.12 mM) were determined. Serum nitrite and nitrate concentrations were measured in a patient following an overdosage of isobutyl nitrite. The method is applicable for nitrite/nitrate studies in plasma at these concentrations.