比重瓶法测颜/填料真密度脱气方法的改进

目前我国颜料、填料真密度值测定普遍执行 GB1713-1989比重瓶法标准。在工业生产检测时,常以蒸馏水或煤油为液体介质,与之相应的除气法有煮沸法和真空法。为了达到良好的脱气效果, 前者需将比重瓶置于50 g·L-1氯化钠溶液中煮沸 2 h,耗时较长,如果比重瓶内温度低于100℃时,会     

乳化体系对薰衣草香料液体纳米胶囊形成能力的影响

本文以壳聚糖为壁材、以薰衣草香料为芯材,考察了乳化体系对薰衣草香料液体纳米胶囊形成能力的影响.本文所选用的乳化剂包括:Tween-20、Tween-40、Tween-60、Tween-80、Tween-85、CO-40及Span-80.首先,分别以Tween-20、Tween-40、Tween-60、Tween-80、Tween-85及CO-40为乳化剂制备薰衣草香料液体纳米胶囊并绘制相关伪三元相图,考察了乳化剂结构对液体纳米胶囊形成能力的影响.随后将Tween-60与Span-80复配,考察乳化体系的亲水亲油平衡值(HLB值)对液体纳米胶囊形成能力的影响.另外还考察了三种助乳化剂:乙醇、1,2-丙二醇及正丁醇以及乳化剂与助乳化剂质量比(Km值)对液体纳米胶囊形成能力的影响.最后,借助动态光散射技术(DLS)、电导率等表征手段,研究了乳化体系与芯材的质量比(S:O)对所制备的薰衣草香料纳米胶囊的粒径及其粒径分布、透光率以及结构类型的影响.结果表明,以CO-40与Span-80复配作为乳化剂, 1,2-丙二醇为助乳化剂, Km值为3, S:O值大于7:3时,可以制得可无限稀释的粒径约为10 nm、低分散且透明的薰衣草香料液体纳米胶囊.     

反相乳液聚合法制备丙烯酰胺-丙烯酸铵共聚物

以煤油为连续相,水为分散相,Span-80/Tween-80为复配乳化剂,过硫酸铵为引发剂,丙烯酰胺、丙烯酸和氨水为原料,采用反相乳液聚合法合成了丙烯酰胺-丙烯酸铵共聚物絮凝剂.考察了乳化剂种类及用量、引发剂浓度、单体浓度、EDTA用量、聚合温度等对共聚物特性黏数的影响.确定了最佳实验条件,利用FTIR对样品进行了表征.     

正负极同电场静电纺丝电场性质及其机理

利用高压直流正负极同电场静电纺丝方法, 制备了聚(3-羟基丁酸-co-4-羟基丁酸酯)共聚物的超细纤维, 实验发现, 正负极同时工作, 形成的宏观纤维形貌与单极相比截然不同, 纤维形态呈现出“蜘蛛网”的变化趋势. 用电磁学理论建立了数学模型. 电压控制在8.0 kV, 溶液质量分数为20％, 电导率控制在0.002—46.7 μS/cm时, 正负极同电场工作时纺丝速率比单极高十几倍; 纤维拉伸取向好于单极纺丝, 该方法为静电纺丝产业化提供了新的思路.     

酚类化合物非水毛细管电泳中静电相互作用分离机理

在非水毛细管电泳(non-aqueous capillary electrophoresis, NACE)中, 添加剂与分析物间的静电相互作用是影响分离的重要因素. 以四烷基溴化铵类化合物为添加剂, 考察了其结构、浓度以及运行介质中水对基于静电相互作用的分离的影响, 并对多种酚类化合物NACE的分离机理进行了探索. 研究发现烷基链越短的添加剂分离能力越强, 且存在获得最大分离度的最佳添加剂浓度. 运行介质中水的存在导致分离效果变差. 此外, 静电相互作用与酚的分子结构相关, 认为能够根据酚的分子结构对分离结果进行预测. 对2种萘酚位置异构体以及5种对位取代苯酚进行了NACE分离, 结果良好. 针对静电相互作用分离的机理研究有助于推广到其他化合物NACE分离分析方法研究上.     

静电纺丝技术制备无机纳米纤维材料的应用

高压静电纺丝技术是一种简单通用的制备聚合物及无机纳米纤维材料的方法. 本文综述了利用高压静电纺丝技术制备的无机纳米纤维材料在能源、 纳电子器件、 催化以及传感器等领域的研究进展, 并对其发展前景进行了展望.     

二-(2-乙基己基)磷酸萃取锰(Ⅱ)的研究

在25±1℃下用分配法研究了HDEHP-煤油从硫酸盐介质中萃取Mn(Ⅱ)以及HDEHP-TOPO-煤油协同萃取Mn(Ⅱ)的机理;考察了介质pH、金属浓度、萃取剂浓度、温度和中性膦氧试剂对萃取的影响。     

用低功率微波热雾化器与十字交叉气动雾化器作为ICP-AES进样装置的比较

在 ICP- AES中 ,最常用来引入液体样品的方法是雾化法 .因此 ,雾化器雾化效率的高低直接影响到 ICP- AES的分析性能 [1,2 ] .目前 ,在 ICP- AES中最常用的雾化器是气动雾化器 (PN) .它的优点是简单、稳定性好 ;缺点是产生的雾滴的直径范围很宽 (一般为 1～ 50 μm) ,进样效率低 ,一般仅为 1 %～3% [3] .热雾化器是近年发展起来的一种雾化效率较高的雾化法 ,已被越来越多地用于 ICP- AES[4～ 7] .热雾化法的雾化原理与同轴气动雾化法类似 ,不同之处在于 :对于热雾化法来说 ,(1 )雾化所需的气体来自于液体样品本身而不是外加的惰性…     

离子液体对胶束电动色谱胶束微结构以及分离效果的影响

考察了离子液体对胶束电动色谱胶柬微结构以及分离效果的影响.研究结果表明,离子液体使胶束的表面电荷密度变小、粒径变大及其内核极性增大.以泼尼松、氢化可的松和泼尼松龙为分析对象,氢化可的松与泼尼松龙在十二烷基硫酸钠(SDS)胶束体系中不能实现分离.而在SDS-离子液体混合介质(20 mmol/L SDS-10 mmol/L...     

离子液体-超声波辅助萃取火焰原子吸收法测定油画棒中的可迁移微量Cd2+

以离子液体为萃取介质,超声波辅助萃取油画棒中的可迁移微量Cd2,以硝酸溶液反萃取后用火焰原子吸收法测定镉.考察了主要影响因素对萃取效果的影响.结果表明,以1-丁基-3-甲基咪唑六氟磷酸盐离子液体为萃取介质,溶液pH值为9.0、金属螯合剂用量为2.00 mL、离子液体的用量为2.00 mL、反萃剂为4.00 mL1.00...     

高压芒刺静电场对小鼠LFA-1和ICAM-1表达的影响

采用不同电压高压芒刺静电场对小鼠进行全身辐射,荧光免疫流式细胞术检测蛋白表达量的变化.通过时程/量效研究不同电压高压芒刺静电场对细胞表面分子LFA-1和ICAM-1的影响.剂量效应结果表明,LFA-1和ICAM-1在10～20 kV之间处理组的表达量明显高于对照组（P＜0.01）;在30 kV以上电压表达量明显降低（P＜0.05）;时间进程研究结果表明,处理后2 h开始实验组表达量与对照组相比差异显著,一直持续到24 h.不同电压高压芒刺静电场可引起ICAM-1和LFA-1不同的生物效应,二者的相互作用在免疫调节反应中发挥重要功能.     

高强度聚乙烯醇水凝胶微球的制备

以三氯甲烷/丙酮为凝固液, 用高压静电技术制备了高强度、物理交联的聚乙烯醇(PVA)水凝胶微球. 研究了凝固液组成、PVA溶液浓度、温度和湿度、电场强度、进样速度及微球冷冻次数等对PVA微球的形貌、粒径和强度的影响. 结果表明, 采用常压水蒸气控制PVA溶液温度与湿度的高压静电技术, 可克服高浓度PVA溶液在强电场下出现微丝现象, 形成的水凝胶微球具有强度高、粒径在一定范围内可控的特点.     

Control of aqueous droplets using magnetic and electrostatic forces

Basic control operations were successfully performed on an aqueous droplet using both magnetic and electrostatic forces. In our droplet-based microfluidics, magnetic beads were incorporated in an aqueous droplet as a force mediator. This report describes droplet anchoring and separation of the beads from the droplet using a combination of magnetic and electrostatic forces. When an aqueous droplet is placed in an oil-filled reservoir, the droplet sinks to the bottom, under which an electrode had been placed. The droplet was adsorbed (or anchored) to the bottom surface on the electrode when a DC voltage was applied to the electrode. The magnetic beads were removed with magnetic force after the droplet had been anchored. Surfactant addition into droplet solution was very effective for the elimination of electric charge, which resulted in the stable adsorption of a droplet to hydrophobic substrate under an applied voltage of DC 0.5-3 kV. In a sequential process, small volume of aqueous liquid was successfully transferred using both magnetic and electrostatic forces.     

双模高压电源在填充型电渗泵流量控制中的应用

研制了两台填充型电渗泵,利用双模对接高压电源可以产生0～60kV超高压,通过提高操作电压,增加了泵系统产生的流量,给出了电渗泵在高电压范围内电压与流量的关系曲线。实验结果表明,电压与流量在高压范围内仍呈线性关系,线性相关系数达到0.9996。同时,通过条件优化,克服了焦耳热,使电渗泵在高电压范围内稳定运行。     

Electrostatically generated fibers of ethyl-cyanoethyl cellulose

Electrospinning was used to fabricate ethyl-cyanoethyl cellulose [(E-CE)C] fibers from tetrahydrofuran (THF) solutions. It was found that the solution jet is split or atomized during the flight to the grounded collector. Microcavities were detected on the surface of the fibers and these were attributed to the volatilization of the solvent (THF). The thinnest fibers generated had a diameter of about 250 nm. The crystallinity of the fibers varied with the voltage of the electrostatic field and it reached a maximum when the voltage of the electrostatic field was 50 kV.     

Very high-pressure capillary liquid chromatography assisted by voltage

Capillary liquid chromatography at moderately high pressures and capillary electrochromatography (CEC) have been combined to drive the mobile phase through capillary columns packed with small diameter particles. In a column packed with 1.5 microm nonporous particles, linear velocities near 3mm/s were observed when combining inlet pressures of 690 bar (10,000 psi) and an applied voltage of 25 kV. Optimum linear velocity for the column was achieved using a pressure-voltage combination of 350 bar (5000 psi) and 5 kV. Separation efficiencies at near optimum linear velocity agreed with those predicted by the van Deemter equation for liquid chromatography. Retention factors were observed to decrease under pressure-voltage combination as the voltage was increased; such a behavior has been attributed to Joule heating effects.     

加压毛细管电色谱在建立中药黄柏指纹图谱中的方法学研究

以加压毛细管电色谱（pCEC）为技术平台,对其在建立中药黄柏指纹图谱中的方法学进行了研究．通过对提取溶剂、流动相中有机相种类、盐溶液等条件的优化,发现1％盐酸的甲醇溶液为提取溶液,20mmol／LNH4C1溶液．乙腈为流动相梯度洗脱,紫外检测波长为230nm时对其分离效果最好．并通过在色谱柱上施加不同的电压,详细地阐明了pCEC的双重分离机制对分离选择性的影响,发现黄柏中的主要成分药根碱、巴马汀和小檗碱在pCEC模式中随电压的不同,有不同的出峰顺序．当电压为0—4kV时出峰顺序为药根碱、巴马汀和小檗碱,当电压为8—14kV时出峰顺序为药根碱、小檗碱和巴马汀．对此原因进行了详细讨论,同时与微径液相色谱模式进行了比较,说明pCEC可以为复杂样品的分离提供更多更好的分离途径．     

Fast separations of chiral β-blockers on a cellulose tris(3,5-dimethylphenylcarbamate)-coated zirconia monolithic column by capillary electrochromatography

Cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) is an excellent chiral selector for enantioseparation of a wide variety of chiral compounds. The monolithic chiral columns are becoming popular in liquid chromatography and capillary electrochromatography. In this work, we present the fast separation of chiral β-blockers on a CDMPC-modified zirconia monolithic column by capillary electrochromatography (CEC). The porous zirconia monolithic capillary column was prepared by using the sol-gel technology and then zirconia surface modified with CDMPC. The enantioseparations were performed in reversed-phase (RP) eluents of a phosphate solution (pH 4.4) modified with acetonitrile or alcohol. The enantioseparations of a set of eight chiral β-blockers were achieved in less than one minute. Influences of the applied voltage, column temperature, concentration of acetonitrile and the type of alcohol as the organic modifier in the mobile phase, and sample injection time on enantioseparation were investigated. CEC separations at the applied voltage of 10 kV and 15 °C in the ACN-modified mobile phase provided the best resolutions for the analytes studied. Run-to-run and day-to-day repeatabilities of the column in the RP-CEC separation were less than 1 and 2%, respectively.     

A high resolving power multiple reflection matrix-assisted laser desorption/ionization time-of-flight mass spectrometer

Two electrostatic mirrors, mounted symmetrically on the same optical axis facing each other, are used to increase the time-of-flight of molecular ions produced in matrix-assisted laser desorption/ionization (MALDI). The mirrors, which are used in the non-compensating mode, are located between a MALDI ion source and a stop detector. The source is operated at 10.5 kV acceleration voltage using the delayed extraction technique. The high voltage for the mirror arrangement is switched on after the desorption event when the molecular ions have drifted into the region between the mirrors. The ions are trapped by successive reflections of the opposite electrostatic fields in the mirrors until the electric fields are switched off. The number of reflections depends on the speed of the ions when they enter the mirror trap and the ontime of the mirrors. When the electric fields are removed during the motion of the ions towards the stop detector, the ions penetrate the grids of the mirror and reach that detector. The extension of the flight path due to the number of reflections is used to increase the resolving power in time-of-flight spectra. Values of 55,000 for substance-P (MW 1346.7) and 31,000 for bovine insulin (MW 5734) were obtained for single laser shot spectra.     

静电纺丝法制备复合纳米材料

经由溶胶-凝胶法过程,应用静电纺丝机原理,以聚乙烯醇(PVA)和无机盐(LiMn2O4)为前驱物,制备出了含有LiMn2O4无机组分的复合纳米纤维,为复合无机纳米纤维的制备方式供给了一条新的思路。实验中系统地研究了PVA的浓度对其所形成的纤维描摹特征的影响。PVA水溶液用于纺丝的最好质量分数约为8.0%。在实验过程中,随着PVA质量分数的渐渐增加,其所形成纤维的直径也随之渐渐增大,而溶液的黏度也在逐步增大,这就使得溶剂挥发变得越来越难,小液珠的表面难以构成理想的"泰勒锥",电压过小,样品溶液无法纺丝,在针头处成水滴状落在针头下方。电压过大则会在纤维丝上呈现念珠形态,阻碍样品电纺时的形貌。实验表明,在施加18kV的高电压,默认机器的其它设定条件下,依托不同质量分数的PVA溶液可制备出三种不同的纤维。