等摩尔量法测定Fe(Ⅲ)配合物稳定常数的物理化学实验方法探索

等摩尔量递变法可以通过作图快速求算金属配合物的配位数n与配位稳定常数K,相对于常规的实验测定与复杂的后续求算方法,既保证了准确性,又简化了计算。实验方案中设计了吸光度校正,并进行体系pH控制确保定量配位,进一步减小实验测定和求算偏差,提高了实验结果的可靠性。

中药炮制包含的化学实验方法研究

中药炮制是中药材在应用前或制成各种剂型前必要的加工处理过程,中药炮制与化学实验方法有一定的相关性,本文对中药炮制中包含的化学实验方法加以汇总,并做分析和阐释,可为中药炮制工艺和质量标准提供科学依据。

有效提高学习兴趣的化学实验方法探寻

事实说明，实验教学更有利于学生各方面能力的培养。根据实验内容可以选择适当的实验方法，实验方法改变学习兴趣，使学习效果显著。列举几种化学实验方法，分别说明它们的使用情况及特点。

改革分析化学实验教学方法 培养学生创新能力

根据农科高等院校的特点,对分析化学实验中的实验项目的选择、实验内容的扩充、实验方法的改进、实验成绩的评定等诸多方面进行针对性改革,总结出一种经验型的实验教学方法,对培养学生的创新能力具有促进作用。

改革化学实验方法 培养创新能力

江泽民总书记指出:“创新是一个民族进步的灵魂,是国家兴旺发达的不竭动力。”因此,学校培养的学生应具有创新精神和创新能力。怎样在化学实验教学中创新、培养学生的创新能力、实现从重视教学结果到既重视教学结果更重视教学过程的转变以建立新的教学理念呢?

无机化学实验教学的探索与实践

文章讨论了通过无机化学实验教学方法的探索来提高无机化学实验的教学质量。在教学过程中引入多媒体实验教学课件,建立无机化学实验教学网络平台。提高学生的实验技能,使实验教学质量不断提高。

物理化学实验教学改革初探

文章针对物理化学实验课的教学特点,并结合物理化学实验课的教学情况,就该课程的教学改革进行了探讨。论文在不断改进教学方法;根据学科体系精心组织教学内容,合理进行实验的安排和准备工作;加强教学管理和教学方法的研究等方面,结合现状和实例进行论述。

一种测定氨含量的新方法

本文采用微型化学实验方法 ,选择硼酸混合指示剂作为吸收氨气的溶液 ,当溶液变为碱性时 ,指示剂马上由红紫色变为亮绿色。然后以标准盐酸滴定收集完全的氨。实验证明 ,用该法测定氨的含量 ,既可以节约药品又使反应时间缩短了一半 ,同时蒸氨装置简单易于操作。用混合指示剂指示反应 ,其优点是 :变色范围窄(p H5.2～ 5.6)且灵敏 ;反应现象直观 ,能增强学生的感性认识。

奇妙的化学溶洞

用特制的实验装置让晶体盐在5％的磷酸三钠溶液中从上往下生长，几分钟就能观察到反应生成的难溶物，有的似倒挂的钟乳石，有的似顶天立地的石柱，宛如自然界奇妙的溶洞景观。该实验装置设计巧妙，实验现象奇妙，有利于激发中小学生学习化学的兴趣。

以培养学生创新意识为导向的无机化学实验教学

大学生创新意识、创新能力的培养是高校教学改革的重要内容。在实验内容方面，可以通过改进经典实验内容，开设前沿实验项目，加强学科交叉融合，激活学生创新意识；教学方法上可以通过设问、启发、引导的教学方法，培养学生的发散性思维、创新意识和创新能力。

ADSORPTION OF METHYLENE BLUE FROM AQUEOUS SOLUTION ON ATTAPULGITE

Batch adsorption experiments were carried out for the removal of methylene blue (MB) from aqueous solution using attapulgite as adsorbent. The effects of various parameters such as temperature, contact time, the pH value, and attapulgite dosage on the adsorption performance were investigated. The standard curve and regression equation were established by spectrophotometry. The adsorption experimental results showed that the adsorption equilibrium data were well in accord with Langmuir adsorptive model. The optimal result was acquired under the experimental condition of attapulgite dosage 0.18g, MB concentration 50.0mg/L, pH 10, and adsorption time 20min at room temperature.

Synthesis and characterization of an environmentally friendly PHBV/PEG copolymer network as a phase change material

Novel environmentally friendly poly（hydroxybutyrate-co-hydroxyvalerate） and poly（ethylene glycol） （PHBV/PEG） copolymer networks were synthesized through free-radical solution polymerization with PHBV diacrylate （PHBVDA） and polyethylene glycol diacrylate （PEGDA） as macromers. The molecular structure of PHBV/PEG copolymer network was characterized by Fourier transform infrared （FT-IR） and 1H nuclear magnetic resonance （1H NMR）. The morphology of the PHBV/PEG co- polymer network was characterized by polarization optical microscopy. Thermal energy storage properties, thermal reliability and thermal stability were investigated by differential scanning calorimetry （DSC） and thermogravimetric analysis. The results indicated that the PHBV/PEG copolymer network hindered the growth of PEG crystalline segments or PHBV segments. PHBV/PEG copolymer network had a higher latent heat enthalpy, which didn＇t reduce with the components of PHBV in- creased. Moreover, PHBV/PEG copolymer network still had good thermal stability even at 300 ~C. These results suggested that such environmentally friendly copolymer network would have wide applications in phase change energy storage materials.

Synthesis of aminoalkylsilanes with oligo(ethylene oxide) unit as multifunctional electrolyte additives for lithium-ion batteries

Aminoalkylsilanes with oligo(ethylene oxide) units were designed and synthesized as multifunctional electrolyte additives for lithium-ion batteries. The chemical structures were fully characterized by nuclear magnetic resonance (NMR) spectroscopy and their thermal properties, viscosities, electrochemical windows, and ionic conductivities were systematically measured. With adding one of these compounds (1 vol. %, DSC3N1) in the baseline electrolyte 1.0 M LiPF 6 in EC: DEC (1:1, in volume), Li/LiCoO 2 half cell tests showed an improved cyclability after 100 cycles and improved rate capability at 5C rate condition. Electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopic (EDS) analysis confirmed the acid scavenging function and film forming capability of DSC3N1. These results demonstrated that the multifunctional organosilicon compounds have considerable potential as additives for use in lithium-ion batteries.

A further understanding of the cation exchange mechanism for the extraction of Sr^(2+) and Cs^+ by ionic liquid

The cation exchange mechanism was further investigated during the extraction of Sr 2+ and Cs+ using the extractant dicyclo- hexano-18-crown-6 (DCH18C6) in an ionic liquid (IL)1-ethyl-3-methyimidazolium bis[(trifluoromethyl)sulfonyl]imide (C2 mimNTf2 ). The concentrations of both the cation C2 mim + and the anion NTf2 in aqueous phase were detected. The con-centration of NTf2 in the aqueous phase decreased as Sr2+ or Cs+ exchanged into the IL phase. Addition of C2 mim + or NTf2 as well as the variation of the solubility of C2 mimNTf2 influenced the extraction efficiency of Sr2+ or Cs+ .

Electrooxidation of hydroquinone on simply prepared Au-Pt bimetallic nanoparticles

A facile method was used to prepare gold-platinum （Au-Pt） catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts were investigated such as initial ap- plied potential, scan rate and deposition time. Initial applied potential plays a more important role in the preparation of bime- tallic nanoparticles （AuPtNPs） since the kinetics of electrodeposition is in competition with the rate of hydrogen evolution. The AuPtNPs electrodeposited on pencil graphite （PG） were used to study the electrooxidation of hydroquinone. Various parame- ters such as pH, scan rate, concentration of hydroquinone and temperature were studied in the electrooxidation process. Ap- parent activation energy （Ea） for the electrooxidation of hydroquinone, calculated from the Arrhenius plot, shows that AuPtNPs catalysts （electrodeposited on the PG） offer less activation energy （ca. 9.500 kJ mo1-1） than the bare PG （ca. 10.345 kJ mol-1）. The AuPtNPs/PG shows better catalytic performance than the PG electrode due to the greater surface area it provides, thus re- sulting in more active sites available for adsorption of hydroquinone molecules on the surface of the catalyst.

Approach to lattice-related/content-specific spectral ranges of near-infrared diffuse reflectance spectroscopy of cefazolin sodium and the construction of a quantitative model for the determination of cefazolin sodium content in different crystal forms

Cefazolin sodium can form both α- and β-form crystals. It also can form dehydrated crystalline and amorphous products through different production processes. Because different polymorphic medicines usually have different physical and chemical properties, it is critical to emphasize the crystallization control of polymorphic medicines. Near-infrared （NIR） analysis, which incorporates a combination of NIR spectroscopic techniques and multivariate chemometric methods, is considered a powerful tool for the determination of the crystallinity of polymorphic drugs. The selection of optimal spectral ranges that correlate with the lattice specificity and content specificity is crucial to obtaining a specific NIR model. In the present work, near-infrared （NIR） spectra of cefazolin sodium with different crystal forms created through different processes were studied. The results suggest that wavelengths within the range of 9102.7-8597.5 cm-1 is related to the specificity of the cefazolin sodium crystal lattice and that the range of 6001.6-5496.4 cm i is associated with the quantitative content of cefazolin sodium. The two ab- sorptions are caused by the second overtone of the C-H stretching band （3nC-H） and the first overtone of C-H stretching band （2uC-H）, respectively. Using these results, we established a suitable method of constructing a universal quantitative model by using mixed samples in different crystal forms as a calibration set, selecting a content-specific range （6001.6-5496.4 cm-l）, and adding lattice-related spectral ranges where appropriate. This may provide a framework for the construction of prediction models for polymorphic medicines.

Photoelectrochemical performance of a sub-micron structured film with poly(3-methylthiophene) (P3MT)-modified CdTe/ZnO shell-core sub-micron tube arrays

A sub-micron structured film with a poly(3-methylthiophene) (P3MT)-modified CdTe/ZnO shell-core sub-micron tube array has been prepared by a series of electrodeposition processes, and a semiconductor-sensitized solar cell based on this structure was also fabricated. Vertically oriented ZnO sub-micron tubes were obtained on an indium tin oxide (ITO) substrate, and then CdTe nanocrystals and a thin P3MT layer were electrodeposited sequentially onto the walls of the ZnO sub-micron tubes. A suitable thickness of CdTe and P3MT could improve the photovoltaic properties of the solar cell, which was attributed to the enhancement in the light absorption and the decrease in the recombination of photogenerated carriers. In addition, a p–n heterojunction formed between the interface of CdTe and P3MT played an important part in the efficient separation and fast transport of photogenerated carriers in the sub-micron structure. A power conversion efficiency of 1.20% was obtained with this type of solar cell.

Properties of a water layer on hydrophilic and hydrophobic self-assembled monolayer surfaces: A molecular dynamics study

The microscopic behaviors of a water layer on different monolayers （SAMs） are studied by molecular dynamics hydrophilic and hydrophobic surfaces of well ordered self-assembled simulations. The SAMs consist of 18-carbon alkyl chains bound to a silicon（111） substrate, and the characteristic of its surface is tuned from hydrophobic to hydrophilic by using different terminal functional groups （-CH3, -COOH）. In the simulation, the properties of water membranes adjacent to the surfaces of SAMs were reported by comparing pure water in mobility, structure, and orientational ordering of water molecules. The results sug- gest that the mobility of water molecules adjacent to hydrophilic surface becomes weaker and the molecules have a better or- dering. The distribution of hydrogen bonds indicates that the number of water-water hydrogen bonds per water molecule tends to be lower. However, the mobility of water molecules and distribution of hydrogen bonds of a water membrane in hydropho- bic system are nearly the same as those in pure water system. In addition, hydrogen bonds are mainly formed between the hy- droxyl of the COOH group and water molecules in a hydrophilic system, which is helpful in understanding the structure of in- terfacial water.

Mercuric ions induced aggregation of gold nanoparticles as investigated by localized surface plasmon resonance light scattering and dynamic light scattering techniques

With the development of nanosciences, both localized surface plasmon resonance light scattering （LSPR-LS） and dynamic light scattering （DLS） techniques have been widely used for quantitative purposes with high sensitivity. In this contribution, we make a comparison of the two light scattering techniques by employing gold nanoparticles （AuNPs） aggregation induced by mercuric ions. It was found that citrate-stabilized AuNPs got aggregated in aqueous medium in the presence of mercuric ions through a chelation process, resulting in greatly enhanced LSPR-LS signals and increased hydrodynamic diameter. The enhanced LSPR-LS intensity （A/） is proportional to the concentration of mercuric ions in the range of 0.4-2.5 laM following the linear regression equation of A/= -84.7＋516.4c, with the correlation coefficient of 0.983 （n = 6） and the limit of determi- nation （3o-） about 0.10 gM. On the other hand, the increased hydrodynamic diameter can be identified by the DLS signals only with a concentration of Hg2＋ in the range of 1.0-2.5 gM, and a linear relationship between the average hydrodynamic diame- ters of the resulted aggregates and the concentration of Hg2＋ can be expressed as d = -6.16 ＋ 45.9c with the correlation coeffi- cient of 0.994. In such case, LSPR-LS signals were further applied to the selective determination of mercuric ions in lake water samples with high sensitivity and simple operation.

The synthesis, deprotection and properties of poly(γ-benzyl-L-glutamate)

Diethylamine, di-n-hexylamine, dicyclohexylamine and triethylamine have been used as initiators for the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride （BLG NCA） to synthesize poly（γ-benzyl-L-glutamate） （PBLG）. The relationship between the molecular weight of PBLG and the molar ratio of monomer and initiator was studied. With dicy- clohexylamine as initiator, the influence of monomer concentration, and reaction temperature and time on the polymerization of BLG NCA was examined. Three reagents were used for the deprotection of benzyl groups in PBLG, including hydrobromic acid/acetic acid （33 wt.%）, NaOH aqueous solution and trimethylsilyl iodide （TMSI）. Through examining the molecular weight of PLGA obtained using different deprotection methods, it was revealed that TMSI could minimize chain cleavage in the process of deprotection and retain the degree of polymerization. The biocompatibilities of PBLG obtained using different initiators were evaluated by a live/dead assay against L929 fibroblast cells. The in vitro cytotoxicities of PLGA obtained using different deprotecting agents were evaluated by a methyl thiazolyl tetrazolium assay. The results revealed that both PBLG and PLGA exhibited good biocompatibilities.