ZnAc2·2H2O在空气中的热分解动力学研究

用TG/DTA,DSC和XRD技术研究了固态物质ZnAc2.2H2O在空气中的热分解过程.结果表明,ZnAc2.2H2O在空气中发生两步分解,其失重率与理论计算失重率相符.XRD结果表明,ZnAc2.2H2O分解的最终产物为ZnO.用Friedman法和Flynn-Wall-Ozawa(FWO)法求得分解过程的活化能E,并通过多元线性回归方法给出了可能的机理函数.ZnAc2.2H2O在空气中两步分解的活化能分别为119.82和66.82kJ/mol.     

Thermal Studies on Ammonium Uranates

Ammonium uranates are important intermediates in the preparation of nuclear fuel UO₂. These can generally be prepared through two different routes: heterogeneous (conventional) and homogeneous methods of precipitation. In the conventional method, ammonium hydroxide, gaseous ammonia and ammonium carbonate are the precipitating agents. In the homogeneous method, urea hydrolysis is used to generate in situ ammonia needed for precipitation. For the present studies, ammonium hydroxide is used for the conventional and urea for the homogeneous methods of precipitation. The uranates, thusprepared, are characterized by thermogravimetry (TG), differential thermogravimetry (DTG)and differential thermal analysis (DTA). Thermally the numbers of decomposition steps are identical for both uranates but the temperatures of the decomposition and mass losses vary. The intermediate and final oxides are identified by X-ray diffractometry (XRD). This revised version was published online in July 2006 with corrections to the Cover Date.     

Application of chemometrically processed chemical and thermoanalytical data for quality control of soybean oils

The quality assessment of commercial soybean oils was evaluated on the basis of chemical and thermal analyses. The most substantial chemical parameters, viz. the density, refractive index and saponification, iodine and acid numbers were estimated. The thermal parameters were determined on the grounds of the TG and DTG curves. There are temperatures for the onset, end and successive mass losses. To find the relation between the chemical and thermal parameters, regression and principal component analyses were applied. The results of principal component analysis indicate that the TG and DTG techniques are at least in equal degree useful in defining the quality of soybean oils, as compared with the chemical analyses.     

消旋卡多曲在空气中的热分解动力学

用热分析(TG/DTA/DSC)技术研究了消旋卡多曲(C₂₁H₂₁NO₄S)在空气中的热分解过程. 热分析结果表明, 消旋卡多曲在空气中一步分解, 其熔点为77.4 ℃. 用Friedman法, Flynn-Wall-Ozawa (FWO)法和ASTM E698法求取了分解过程的活化能E, 并通过多元线性回归法给出了可能的机理函数.     

A Thermal Analysis Study of Hydroxy Benzoic Acid Derivatives Using Rising Temperature Thermogravimetry

Hydroxy benzoic acids were subjected to rising temperature thermogravimetric analysis. After optimizing the procedural variables, the kinetics of decomposition was determined and methyl paraben was taken as the calibration compound to characterize the evaporation patterns for the ortho and meta derivatives. The E _act values for ortho, meta and para derivatives were 64.8, 78.2, and 119.1 kJ mol^–1, respectively. The Antoine and Langmuir equations were utilized to determine the coefficient of evaporation k, which was 124525±0.8, units being in the SI system. The vapor pressure plots were generated for the ortho and meta derivatives; ΔH _vap for these two compounds were obtained as 66.7 and 80.4 kJ mol^–1, respectively. This revised version was published online in August 2006 with corrections to the Cover Date.     

The Thermal Decomposition of Magnesium(II) Complexes with Acetic and Halogenacetic Acids

Thermogravimetry (TG), differential thermal analysis (DTA) and other analytical methods have been applied to the investigation of the thermal behaviour and structure of the compounds Mg(Ac)₂ × 2H₂ O(I), Mg(ClAc)₂ ×2H₂ O(II) and Mg(Cl₂ Ac)₂ ×H₂ O(III) (Ac =CH₃ COO⁻ , ClAc =ClCH2COO⁻ , Cl ₂ Ac =Cl₂ CHCOO⁻ ). The solid phased intermediate and resultant products of thermolysis had been identified. The possible scheme of destruction of the complexes is suggested. The halogenacetato magnesium complexes (II–III) are thermally more stable than the acetatomagnesium complex I. The final products of the decomposition of compounds were MgO. Infrared (IR) data suggest to a unidentate coordination of carboxylate ions to magnesium ions in complexes I–III. This revised version was published online in August 2006 with corrections to the Cover Date.     

拟多维高效液相色谱及其应用于苯甲酸衍生物的分离

利用一种新的高效液相色谱洗脱技术，采用ＰＨ缓冲液／有机溶剂二元洗模式，对苯甲酸衍生物系列与苯衍生物系列混合物在反相柱上进行分离，得到好的分离效果。     

新型交联壳聚糖树脂的制备及其对苯甲酸的吸附行为研究

以壳聚糖为原料,甲醛为预交联剂,环氧氯丙烷为交联剂,通过反相悬浮交联法制备出新型壳聚糖树脂,并用红外光谱和扫描电镜对其结构进行表征.测定了不同温度下新制备树脂自水中吸附苯甲酸的等温线,计算了吸附过程的热力学参数.并用Freundlich方程对实验数据进行拟合,发现该方程适用于所研究的吸附体系.体系的热力学与吸附机理密切相关,当苯甲酸浓度较低时,吸附为放热过程,体系熵减少,降温有利于吸附;当苯甲酸浓度较高时,吸附为吸热过程,体系熵增加,升温有利于吸附.     

Synthesis and Thermal Study of the Barium Complexes with 8-hydroxyquinolinate Derivatives

In this present work, barium ion was reacted with different ligands which are 5,7-dibromo 5,7-dichloro, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinoline, in acetone/ammonium hydroxide medium under constant stirring and the obtained compounds were as follows: (I) Ba[(C₉ H₄ ONBr₂ )₂ ]⋅1.5H₂ O; (II) Ba[(C₉ H₄ ONCl₂ )(OH)]⋅1H₂ O; (III) Ba[(C₉ H₅ ONI)₂ ]⋅1H₂ O and (IV) Ba[(C₉ H₄ ONICl)₂ ]⋅5H₂ O, respectively. The compounds were characterized by elemental analysis, infrared absorption spectrum (IR), inductively coupled plasma spectrometry (ICP), simultaneous thermogravimetry-differential thermal analysis (TG-DTA) and differential scanning calorimeter (DSC). The final residue of the thermal decomposition was characterized as orthorhombic BaBr₂from (I); the intermediate residue, as a mixture of orthorhombic BaCO₃ and BaCl₂ and cubic BaO and the final residue, as a mixture of cubic and tetragonal BaO and orthorhombic BaCl₂ (II); the intermediate residue, as orthorhombic BaCO₃ and as a final residue, a mixture of cubic and tetragonal BaO from (III); and the intermediate residue, as a mixture of orthorhombic BaCO₃ and BaCl₂ and as a final residue, a mixture of cubic and tetragonal BaO and orthorhombic BaCl₂ from (IV). This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Decomposition of Hydrated Lanthanide Picrates by TG/DTG and DSC Analyses

Hydrated lanthanide picrates with a composition of: Ln(pic)₃⋅xH₂O (Ln=La–Lu, Y) were synthesized and characterized. Thermal decomposition of the picrates by TG/DTG and DSC techniques are reported. This revised version was published online in July 2006 with corrections to the Cover Date.     

应用量化参数和CoMFA法研究苯甲酸类化合物的结构和其pKa值的相关性

人工神经网;应用量化参数和CoMFA法研究苯甲酸类化合物的结构和其pKa值的相关性     

Preparation and Thermal Decomposition of Polyacrylamide and its Derivatives by Plasma-initiated Polymerization

Polyacrylamide (PAM), poly(N,N-dimethylacrylamide) (PDMA) and poly(N,N-diethylacryl-amide) (PDEA) were synthesized by plasma-initiated polymerization. Both wet and dry polymers were prepared. The states of the water absorbed in the wet and dry samples were studied directly by means of TG, and the stabilities of the dry polymers in the process of thermal treatment were investigated by FT-IR. The activation energy of release of the bonded water was calculated by the Kissinger method. The water absorbed in the polymers was found to be in two states, i.e. weakly-bonded water and bonded water, and the absorbed water content varied with the monomer concentration, the plasma duration time and the type of polymer.This revised version was published online in November 2005 with corrections to the Cover Date.     

Thermal Decomposition of Strontium and Barium Malonates

The thermal decomposition of strontium and barium malonates has been studied isothermally and non-isothermally employing simultaneous TG-DTG-DTA, DSC, XRD and IR spectroscopic techniques. DSC of these malonates has been recorded both in oxygen and nitrogen atmospheres. The decomposition is a single step process and the end product formed is carbonate. The energy of activation and frequency factor values for the decomposition of strontium malonate are 547 kJ mol⁻¹ and 10⁴¹ s⁻¹ respectively. The activation energy and frequency factor values for isothermal dehydration of barium malonate sester-hydrate are 57–111 kJ mol⁻¹ and 10⁷–10¹² s⁻¹ respectively and the corresponding values for decomposition from DSC are 499.5 kJ mol⁻¹ and 10⁴⁴ s⁻¹ respectively. The higher thermal stability of strontium malonate as compared to that of barium salt is ascribed to its being anhydrous so that decomposition proceeds without restructuring. Their thermal stabilities have also been compared with that of respective oxalate salts. This revised version was published online in July 2006 with corrections to the Cover Date.     

蒽与苯甲酸及其衍生物之间的作用机理研究

用紫外差光谱、红外光谱法和荧光猝灭法研究了典型多环芳烃蒽与苯甲酸及其羟基取代衍生物邻羟基苯甲酸和对羟基苯甲酸之间的作用机理。实验结果表明,在此芳香羧酸与蒽之间存在定向的、特异性的作用,其作用方式受到反应物结构和环境酸度的影响。对苯甲酸和邻羟基苯甲酸而言,当pH<pKa时,二者之间以蒽离域大π电子与羧基质子之间的π-H氢键作用为主,pH>pKa时,π-π电子给体受体作用逐渐成为主要结合方式。邻位羟基的存在使得苯甲酸与蒽的作用强度明显降低。对羟基苯甲酸特殊的D-π-A型分子结构使得它在溶液中形成平面多分子聚集体,这种多分子聚集体的生成使得对羟基苯甲酸与蒽的结合方式不随酸度变化,在pH2.0~10.0的范围内均以π-π电子给体受体作用相结合,且结合强度大于苯甲酸和邻羟基苯甲酸。     

鲍鱼多糖Hal-A的热分析研究

采用热重、热重-红外谱联用及差示扫描量热法，对鲍鱼多糖进行热分析研究 ，结果表明鲍鱼多糖在空气和氮气氛中，230 ～ 340 ℃之间发生剧烈的分解反应 。氮气氛中，是吸热的分解过程；而空气氛中，是放热氧化反应，并且在453 ℃左 右，有另一个急剧的氧化裂解过程。与淀粉、肝素、甲壳素和半乳糖的热分析比较 ，含有硫酸酯的鲍鱼多糖和肝素热稳定性较低，含氨基的甲壳素最高，这反映出不 同基团对多糖热稳定性的影响。     

Thermal analysis of crude oils and comparison with SIMDIST and TBP distillation data

Four commercial Saudi Arabian crude oils were characterized by thermogravimetry (TG) and differential thermal analysis (DTA). These crude oils, Arab Berri (AB), Arab Light (AL), Arab Medium (AM) and Arab Heavy (AH), were also subjected to the traditionally employed true boiling point (TBP) distillation and simulated distillation (SIMDIST). The TG/DTA data show that the hydrocarbons present in these crude oils fall into four groups: the volatiles, the low molecular weight, the medium molecular weight and the high molecular weight compounds. These four types of hydrocarbons were observed to display certain trends, such that the volatile and low molecular weight hydrocarbons increased, while the medium and high molecular weight hydrocarbons decreased with the lightness of the crude. The volatile contents of AB, AL, AM and AH crude oils up to 280°C were 50.1, 42.2, 42.3 and 38.5 mass percent, respectively. This confirms that AB is the lightest of these crude oils with maximum volatile content. The mass percentage loss from the TG results is in good agreement with the percentage distilled from TBP (ASTM D 2892) and SIMDIST. During evaporation, the TG mass loss follows a similar trend to those of the TBP and SIMDIST results and thus behaves like distillation. During the oxidative degradation, the TG curve shows a higher mass loss as compared to the distillation data. The higher deviation of the TG mass loss and percentage distilled at the higher-temperature end of the curve may be attributed to the higher content of asphaltenes and carbonaceous material present in AH as compared to the AB crude oil. At around 200°C, the TG mass loss curve intersects the TBP and SIMDIST curves and shows a derivation from distillation behaviour. This intersection temperature of the TG and distillation curves is observed to decrease with the heaviness of the crude and can be an indication of the onset of thermal degradation of hydrocarbons present in the crude oil. On the whole, the TG data closely resemble the distillation results.     

Thermal Decomposition of Mg(II) Complexes with Ronicol

The thermal decomposition of the complexes Mg(Clac)₂ (ron)₂ ×3H₂ O(I), Mg(Cl₂ ac)₂ (ron)₂ ×3H₂ O(II) and Mg(Cl₃ ac)₂ (ron)₂ ×3H₂ O(III), where Clac =ClCH₂ COO^- , Cl ₂ ac =Cl₂ CHCOO^- , Cl ₃ ac =Cl₃ CCOO^- and ron =3-pyridylcarbinol (ronicol) had been investigated in air atmosphere in temperature range 20–1000°C by means of TG and DTA. The composition of the complexes and the solid state intermediate and resultant products of thermolysis had been identified by means of elemental analysis and complexometric titration. The possible scheme of destruction of the complexes is suggested. The final product of the thermal decomposition was MgO. The thermal stability of the complexes can be ordered in the sequence: I<III<II. IR data suggest that ronicol was coordinated to Mg(II) through the nitrogen atom of its heterocyclic ring. This revised version was published online in July 2006 with corrections to the Cover Date.     

Use of Methods of Thermal Analysis in Studying Ceramic Materials on the Basis of Al2O3, ZrO2, Si3N4, SiC and Inorganic Binder

By thermoanalytical methods TG, DTG, DTA there have been investigated the processes occurring during the formation of ceramic materials on the basis of Al₂O₃, ZrO₂, Si₃N₄, SiC,and inorganic binder. IR spectroscopy has been an additional research method. It's been determined that with the use of H₃PO₄ as the binder for ceramic materials, the mechanisms of thermal decomposition are connected with the following processes: 1. removal of weakly tied and crystallized water in the temperature range of120–230°C, the removal being characterized by the endothermic effect, 2. interaction of the initial powder components of the ceramic materials with orthophosphoric acid conditioned by a strong exothermic effect on the DTA curve in the range of 230–530°C, 3. overlapping of endo- and exo-effects, testifying to a complex mechanism of thermal transformations, 4.oxidizing of the non-reacted silicon at the temperature of 720(760)°C, an increase of mass is observed on the TG curve as a result of the formation of SiO₂ – crystoballite. This revised version was published online in July 2006 with corrections to the Cover Date.     

NMR Studies on the Subacute Biochemical Effects of Aristolochic Acid on Rat Serum

The subacute effect of aristolochic acid （AA） on rat serum was studied by NMR method. The biochemical effects induced by AA were characterized by an increase in the amounts of creatinine, trimethylamine N-oxide, acetoacetate, acetate and 3-D-hydroxybutyrate and lactate in serum from ^1H NMR spectra. Principal component analysis was used for further comparing the similarities of ^1H NMR spectral profiles of serum from rats treated with AA and model toxins.     

热分析技术在药物研究中的应用

本文简要介绍了热分析技术在药学领域中的重要性及其应用。由于热分析技术具有试样微量化、快速简便、不用分离试样、不用溶剂、适用范围广、曲线易于解析等优点,在药学研究和药品质量检验等方面,热分析技术将发挥更重要的作用。