一种保温外墙涂料的研制

以硅丙乳液、纯丙乳液为基料,云母粉、海泡石、滑石粉、高岭土、膨润土为辅助填料,空心玻璃微珠为隔热骨料,钛白粉、轻钙为颜填料,丙二醇为粘结剂,加人适当的分散剂、消泡剂、成膜助剂等助剂,研制了一种保温外墙涂料,其常规性能符合外墙涂料的相关标准要求,具有明显的保温隔热效果。     

小分队视导:促进教师专业发展的新型教研方式

针对当前区域教研存在的问题,阐述了"小分队视导"这一新型教研方式的工作特点和以问题为核心、以课例为载体、以名师为示范、以反思为宗旨、以"教学新时空"为平台、以反馈为手段,来促进化学教师专业发展的实践与思考.     

火焰原子吸收光谱法测定高锑烟尘中的银、铅、镉

建立了火焰原子吸收光谱法测定高锑烟尘中的银、铅、镉的分析方法。试样经王水、高氯酸溶解后,利用四价锑的溴化物沸点较低的性质,将锑挥发除去,以消除基体锑对测定的干扰,在盐酸-高氯酸-硫脲介质中实现了银、铅、镉的连续测定。方法检出限:Ag为0.003 7μg/mL,Pb为0.019 8μg/mL,Cd为0.001 6μg/mL。相对标准偏差(RSD,n=11):Ag为0.92%~1.04%,Pb为1.29%~2.21%,Cd为1.99%~2.22%。加标回收率:Ag为99.30%~101.8%,Pb为98.60%~102.5%,Cd为98.40%~104.0%。方法准确、可靠、简便、快速,完全适用于高锑烟尘中银、铅、镉的测定。     

植物还原法制备负载型金纳米催化剂催化乙醇选择氧化反应

采用侧柏叶提取液还原氯金酸制备负载型金纳米催化剂,通过乙醇选择氧化反应,筛选出催化性能较好的TiO2载体。以TiO2载体为载体,考察了Au负载量、焙烧温度、催化剂用量、碳酸氢钠添加量及催化剂反应条件(时间、温度、压力)等因素对乙醇选择氧化反应的影响。结果表明,1.5%Au/TiO2催化剂(Au负载量为1.5%,质量分率,下同)催化乙醇选择氧化反应性能最佳,产物为乙醛、乙酸乙酯和缩醛,0.5%碳酸氢钠添加剂可抑制缩醛的生成,并可显著提高乙醇转化率和乙酸乙酯选择性。通过优化催化反应条件(1.5%Au/TiO2催化剂焙烧温度为400℃、用量为0.4 g、反应温度为100℃、氧气压力为3 MPa、反应时间为3 h时),乙醇转化率为47.9%,乙酸乙酯选择性为89.1%。     

翻白草中鞣质的微波提取工艺研究

采用微波辅助提取方法,以提取剂浓度、pH值、液固比、微波提取时间、温度等为考察因素,并以提取物中总鞣质的提取率为评价指标,使用磷钼钨酸-干酪素分光光度法为定量测定方法,在单因素实验的基础上,通过正交实验优化翻白草中鞣质的提取工艺.实验结果表明,最佳提取条件为:使用70%甲醇作为提取剂、液固比40∶1、提取液pH为8.0、提取温度为40℃、提取时间为10 min.还对翻白草不同部位(根、茎、叶)的鞣质含量进行分析,发现根部中鞣质的含量最大,其次为茎和叶.此外,采用高效液相色谱法对翻白草中鞣质的种类进行定性分析.     

成都市东郊土壤中重金属元素垂直分布研究

采用王水消解样品,利用原子吸收分光光度法,对重金属元素(Cu、Pb、Zn、Cd)在成都市东郊土壤中的垂直分布进行了研究。该法对Cu的回收率为98%~104%,精密度为2.75%;Pb的回收率为95~97%,精密度为3.11%;Zn的回收率为99%~101%,精密度为2.31%;Cd的回收率为97%~102%,精密度为3.32%,测定方法简单、准确。     

NaOH改性稻壳对亚甲基蓝的吸附性能研究

采用NaOH改性稻壳为吸附剂,探究稻壳在不同条件下对亚甲基蓝的吸附性能.同时利用比表面积测定、扫描电镜、红外光谱等表征手段对改性前后的吸附剂进行物化特性、样品形貌等分析.结果 表明,采用4 wt.％NaOH改性稻壳,亚甲基蓝溶液的初始浓度为80 mg·L-1、pH为6.0、温度为25℃、震荡时间为12 h、吸附剂用量为...     

微波辅助-顶空液相微萃取在线联用-高效液相色谱法测定环境水样中的敌敌畏

基于微波辅助-顶空液相微萃取联用(MAE-HS-LPME)这一样品前处理方法,采用高效液相色谱法(HPLC)对水样中的敌敌畏残留量进行了测定。对影响萃取的因素如萃取剂、微波辐射功率、萃取时间、离子强度和样品基质的pH值等进行了考察。萃取条件为: 选用二甲苯作萃取剂,萃取时间为15 min,微波辐射功率300 W,NaCl含量为5%,pH为2.5。在最佳条件下,敌敌畏的检出限(信噪比为3时)为0.96 μg/L,定量限(信噪比为10时)为3.20 μg/L,萃取富集倍数为54,实际水样的加标回收率为87.4%～103%。与传统的前处理方法相比,本方法具有简便、快速、高效、节省溶剂、选择性好、应用范围广的特点。     

辉光放电电解等离子体引发合成聚丙烯酸钠/腐植酸复合高吸水性树脂

以丙烯酸和腐植酸为原料,N,N-亚甲基双丙烯酰胺为交联剂,在水溶液中采用辉光放电电解等离子体引发聚合反应制备聚丙烯酸钠/腐植酸复合高吸水性树脂。 考察了放电电压、交联剂、丙烯酸中和度、后聚合温度、腐植酸钠和丙烯酸的含量对树脂吸水率的影响,讨论了树脂在0.9%氯化钠溶液中的溶胀速率和不同pH值溶液中的溶胀行为。 用红外光谱和热重分析分别对产物进行了结构表征和稳定性测试,结果表明,最佳的合成条件为：放电电压470 V、交联剂质量分数为0.6%、腐植酸钠质量分数为4%、丙烯酸质量分数为10%、中和度60%、后聚合温度70 ℃。 所得复合树脂对蒸馏水的吸水率为1152 g/g,对0.9%NaCl溶液的吸水率为89 g/g,800 ℃后复合树脂残留率为44.3%。     

国家对调味品等食品保质期的规定

1、酒类：瓶装普通熟啤酒保质期为2个月,特制啤酒4个月;瓶装葡萄果露酒为半年。2、饮料类：果汁汽水、果味汽水、可乐汽水,玻璃瓶装保质期为3个月,罐装6个月;果汁玻璃瓶装为6个月。3、罐头类：鱼肉禽类罐装、玻璃瓶装保质期2年;果蔬菜类罐装、玻璃瓶装保质期为15个月;     

芳香胺氰乙基化催化反应的研究进展

从催化剂的应用角度,总结了酸、路易斯酸、固体酸性氧化物、强酸性阳离子交换树脂、无机碱、有机碱以及由酸/路易斯酸、路易斯酸/路易斯酸、路易斯酸/路易斯碱等催化体系在催化芳香胺的氰乙基化反应中的应用进展,阐述了芳香胺的氰乙基化反应的酸催化和碱催化机理,并对芳香胺的氰乙基化反应的今后发展方向进行了展望。     

钨酸催化氧化环己烯合成己二酸

以钨酸/有机酸性添加剂为催化体系, 在无有机溶剂、相转移剂的情况下, 催化30%过氧化氢氧化环己烯合成己二酸. 当钨酸∶有机酸性添加剂∶环己烯∶过氧化氢＝1∶1∶40∶176(摩尔比, 钨酸用量为2.5 mmol)时, 使用有机酸性添加剂考察钨酸的催化性能, 结果表明以钨酸/间苯二酚催化氧化环己烯的催化效果最优, 反应8 h时己二酸分离产率达90.9%、纯度为～100%; 而不使用有机酸性添加剂时, 己二酸分离产率只有72.1%, 产品纯度为96.2%. 当使用磺酸水杨酸、草酸、水杨酸为有机酸性添加剂时, 随反应时间的增加, 己二酸分离产率均升高, 但反应6 h以后, 己二酸分离产率随时间的变化不明显. 当磺酸水杨酸用量为2.5 mmol时, 己二酸分离产率和纯度均较高. 钨酸-磺酸水杨酸催化体系重复使用五次后, 己二酸分离产率仍可达到80.5%.     

The dimethyldioxirane-mediated oxidation of phenylethyne

The product pattern found for the dimethyldioxirane-mediated oxidation of phenylethyne strongly depends on the reaction conditions. Dimethyldioxirane generated in situ from caroate (HSO(5)(-)) and acetone in acetonitrile-water furnishes phenylacetic acid as the main product. With solutions of dimethyldioxirane in acetone, mandelic acid and phenylacetic acid are mainly formed. The relative abundances of the two acids depend on the residual water present in the dimethyldioxirane-acetone solution. Application of thoroughly dried solutions of the reagent effects increased formation of mandelic acid. When phenylethyne is oxidized by dimethyldioxirane transferred into tetrachloromethane, to minimize traces of water even further, oligomeric mandelic acid is obtained. The results are rationalized by the initial formation of phenyloxirene, which is known to equilibrate with phenylformylcarbene and benzoylcarbene. Subsequent Wolff rearrangement produces intermediate phenylketene, which can be trapped by water as phenylacetic acid or suffer from further oxidation to the alpha-lactone of mandelic acid. The alpha-lactone can either react with water to yield mandelic acid or, under anhydrous conditions, to yield oligomeric mandelic acid. In addition to mandelic acid and phenylacetic acid phenylglyoxylic acid, benzoic acid and benzaldehyde are observed as reaction products. The formation of phenylglyoxylic acid by transfer of two oxygen atoms to the unrearranged carbon skeleton of phenylethyne followed by oxygen insertion into the aldehydic C-H bond of the intermediately formed phenylglyoxal is discussed. In a second pathway this acid is formed by partial oxidation of mandelic acid. Benzaldehyde and benzoic acid are explained as products of the oxidative degradation of the alpha-lactone by dimethyldioxirane. Under in situ conditions benzoic acid is also formed by caroate initiated oxidative decarboxylation of phenylglyoxylic acid and/or intermediate phenylglyoxal.     

Sequential Thin-Layer Chromatography of 2,4-D and Related Compounds

Abstract

Separations and identification of carboxylic herbicidal substances such as 2,4-dichlorophenoxyacetic acid, trichloroacetic acid, 2,4,5-trichlorophenoxyacetic acid and plant growth regulators such as benzoic acid, cinnamic acid, indole-3-acetic acid, β-naphthaleneacetic acid, β-naphthoxyacetic acid, phenoxyacetic acid have been made by sequential thin-layer chromatography on calcium sulphate layer with acetone, benzene, carbon tetrachloride, chloroform, ethyl acetate, dioxan, propanol as solvents and bromophenol blue as detector.     

Synthesis of nanostructured polyaniline via chemical oxidative polymerization: Investigation of morphology and conductivity of the prepared polymers

In this study, nanostructure polyaniline was prepared from aniline monomer via chemical oxidative polymerization in the presence of ammonium persulfate as an oxidizing agent. Interfacial, emulsion, rapid mixing and ultrasonic techniques are used for polymer synthesis. In the interfacial method, chloroform, n-hexane, hexanole and toluene were used as organic solvents and sulfuric acid, methane sulfonic acid and acetic acid were employed as electrolyte solutions. In the emulsion polymerization, dodecyl benzene sulfonic acid and aqueous solution of hydrochloric acid were used as emulsion agent and electrolyte solution respectively. In rapid mixing reaction and ultrasonic method, hydrochloric acid and salicylic acid were used as dopants. The structure, conductivity, morphology and particle size distribution of prepared polymers were investigated after purification and drying by FTIR spectroscopy, scanning electron microscopy and electrical conductivity measurements.     

Efficient homogeneous catalysis of heteropoly acid and its characterization through etherifications of alcohol

A Keggin-type heteropoly acid revealed high catalytic activity for the etherification such as diethylene glycol with ethanol and cyclization of diethylene glycol in the homogeneous liquid. The catalytic activities of the heteropoly acid were much higher than those of conventional acid catalysts such as sulfuric acid, p-toluene sulfonic acid and phosphorous acid at the same catalyst concentrations or the same proton concentrations. On the basis of comparative measurement of electrical conductivity, acidity, and softness of anion for the solutions of acid catalysts, the efficient acid catalysis by heteropoly acid was suggested to due to be the specific properties of the heteropoly anion, which can be characterized by very weak basicity and great softness, together with the large size of the polyhedral structure.     

Vacancy ion-exclusion chromatography of haloacetic acids on a weakly acidic cation-exchange resin

A new and simple approach is described for the determination of the haloacetic acids (such as mono-, di- and trichloroacetic acids) usually found in drinking water as chlorination by-products after disinfection processes and acetic acid. The new approach, termed vacancy ion-exclusion chromatography, is based on an ion-exclusion mechanism but using the sample solution as the mobile phase, pure water as the injected sample, and a weakly acidic cation-exchange resin column (TSKgel OApak-A) as the stationary phase. The addition of sulfuric acid to the mobile phase results in highly sensitive conductivity detection with sharp and well-shaped peaks, leading to excellent and efficient separations. The elution order was sulfuric acid, dichloroacetic acid, monochloroacetic acid, trichloroacetic acid, and acetic acid. The separation of these acids depends on their pKa values. Acids with lower pKa values were eluted earlier than those with higher pKa, except for trichloroacetic acid due to a hydrophobic-adsorption effect occurring as a side-effect of vacancy ion-exclusion chromatography. The detection limits of these acids in the present study with conductivity detection were 3.4 microM for monochloroacetic acid, 0.86 microM for dichloroacetic acid and 0.15 microM for trichloroacetic acid.     

Photostability of Ferulic Acid and Its Antioxidant Activity Against Linoleic Acid Peroxidation

Ferulic acid (4‐hydroxy‐3‐methoxycinnamic acid), a phenyl‐propenoid derivative of cinnamic acid, can undergo photolysis upon UV irradiation. The photodegradation kinetics of ferulic acid were thus investigated in different systems. The micellar solutions did not protect the acid from photodegradation. On the contrary, they catalyzed its degradation at a variable extent depending on the surfactant structure. The photodegradation of ferulic acid in microemulsions was slower than in micelles and near to that in water. TiO₂, habitually employed as a physical sunscreen, showed photocatalytic action toward ferulic acid degradation especially at higher initial concentration of ferulic acid. The action of ferulic acid on the peroxidation of linoleic acid in micelles and microemulsions also was evaluated. When the ferulic acid is absent the peroxidation is continuous while when it is present an induction time of 40 minutes or higher was observed. Accordingly, it is likely that linoleic acid acts as photosensitizer for ferulic acid, and that in turn ferulic acid acts as an antioxidant for linoleic acid, reducing the rate of peroxidation.     

Gold- and gold-palladium/poly(1-vinylpyrrolidin-2-one) nanoclusters as quasi-homogeneous catalyst for aerobic oxidation of glycerol

Glycerol was oxidized catalytically under aerobic conditions in the presence of monometallic nanoclusters of gold on poly(1-vinylpyrrolidin-2-one) (PVP) to give hydroxymalonic acid (tartronic acid) as the major product, together with 2,3-dihydroxypropanoic acid (glyceric acid) and hydroxyacetic acid (glycolic acid) as minor products. In contrast, oxalic acid was selectively obtained when bimetallic Au-Pd:PVP nanoclusters were used as the catalyst.     

Hydroaromatic equilibration during biosynthesis of shikimic acid

The expense and limited availability of shikimic acid isolated from plants has impeded utilization of this hydroaromatic as a synthetic starting material. Although recombinant Escherichia coli catalysts have been constructed that synthesize shikimic acid from glucose, the yield, titer, and purity of shikimic acid are reduced by the sizable concentrations of quinic acid and 3-dehydroshikimic acid that are formed as byproducts. The 28.0 g/L of shikimic acid synthesized in 14% yield by E. coli SP1.1/pKD12.138 in 48 h as a 1.6:1.0:0.65 (mol/mol/mol) shikimate/quinate/dehydroshikimate mixture is typical of synthesized product mixtures. Quinic acid formation results from the reduction of 3-dehydroquinic acid catalyzed by aroE-encoded shikimate dehydrogenase. Is quinic acid derived from reduction of 3-dehydroquinic acid prior to synthesis of shikimic acid? Alternatively, does quinic acid result from a microbe-catalyzed equilibration involving transport of initially synthesized shikimic acid back into the cytoplasm and operation of the common pathway of aromatic amino acid biosynthesis in the reverse of its normal biosynthetic direction? E. coli SP1.1/pSC5.214A, a construct incapable of de novo synthesis of shikimic acid, catalyzed the conversion of shikimic acid added to its culture medium into a 1.1:1.0:0.70 molar ratio of shikimate/quinate/dehydroshikimate within 36 h. Further mechanistic insights were afforded by elaborating the relationship between transport of shikimic acid and formation of quinic acid. These experiments indicate that formation of quinic acid during biosynthesis of shikimic acid results from a microbe-catalyzed equilibration of initially synthesized shikimic acid. By apparently repressing shikimate transport, the aforementioned E. coli SP1.1/pKD12.138 synthesized 52 g/L of shikimic acid in 18% yield from glucose as a 14:1.0:3.0 shikimate/quinate/dehydroshikimate mixture.