-15℃下Na+， K+， Mg2+//Cl-， NO3-， SO42——H2O体系相平衡研究

新疆卤水硝酸盐矿主要含有Na⁺、K⁺、Mg²⁺、Cl^-、NO₃^-、SO₄^2-六种离子，属于高元复杂体系，其合理利用和开发需要不同温度下的相平衡研究作为理论支撑。采用等温溶解平衡法，对Na⁺， K⁺， Mg²⁺//Cl^-， NO₃^-， SO₄^2--H₂O体系在-15℃、NaCl·2H₂O饱和条件下的相平衡进行了研究，并构建了相图。相图中有六个零变量点和八个两盐结晶区，只存在一种复盐KCl·MgCl₂·6H₂O。八个两盐结晶区，分别对应于NaCl·2H₂O+Na₂SO₄·10H₂O、NaCl·2H₂O+NaNO₃、NaCl·2H₂O+KCl、NaCl·2H₂O+KNO₃、NaCl·2H₂O+MgSO₄·7H₂O、NaCl·2H₂O+MgCl₂·8H₂O、NaCl·2H₂O+Mg(NO₃)₂·6H₂O和NaCl·2H₂O+KCl·MgCl₂·6H₂O，其中NaCl·2H₂O+Na₂SO₄·10H₂O共晶区最大，在低温时，硫酸钠的溶解度最小，降温过程中较易结晶析出。与该体系在25℃下的相图相比，复盐种类减少5种，零变量点减少19个，相关系得以极大简化。     

双季戊四醇在3种混合溶剂中的固-液相平衡

采用动态平衡法，在293.15～332.80 K、常压下，测定了双季戊四醇(DPE)在水+(甲醇、乙醇、异丙醇)三种混合溶剂中的溶解度数据。结果表明：DPE在不同质量分数的水+(甲醇、乙醇、异丙醇)混合溶剂中的溶解度随体系温度升高而增大；同一温度下，其在所选取溶剂体系中的溶解度随着甲醇、乙醇或异丙醇质量分数的增大而先增大后减小。λh方程、两参数方程与Apelblat方程均能够对所测定的溶解度数据进行较好的关联；通过修正的van’t Hoff方程计算得到DPE在所选取溶剂体系中Δ_sol H ⁰、Δ_sol S ⁰和Δ_sol G ⁰均大于零，表明DPE在所选取溶剂体系中的溶解过程为吸热、熵增的非自发过程。     

新型着色材料——速溶色浆粉的测试与应用

介绍了通过初级颜料的润湿、研磨与分散、稳定处理技术,使助剂和树脂均匀地包裹在颜料表面,并通过特殊工艺制得水性和油性色浆粉,并赋予了很好的速溶性和分散性。     

Measurement of solubility and diffusion coefficients of ethylene in solid and molten low-density polyethylene with different melt indices

The diffusion behavior of ethylene in polyethylene is of great importance for the polymerization and degassing of polyethylene (PE) industry. Based on the gravimetric sorption and desorption measurement approach, an intelligent gravimetric analyzer is applied to obtain the solubility and diffusion coefficients of ethylene in solid low-density PE (LDPE) with different melt indices at 30°C to 70°C, 0 to 4 atm and in molten LDPE at 160°C to 230°C, 0 to 4 atm, respectively. Results indicate that both the solubility and diffusion coefficients of ethylene in solid LDPE are smaller than those in molten LDPE, while the dissolution enthalpy and diffusion activation energy of ethylene in solid LDPE are higher. In addition, one- and two-dimensional diffusion models are built and the effects of particle size, polymer properties, and operation conditions are systematically investigated on the diffusion behaviors of ethylene in solid and molten LDPE.     

Formulation of solid self-nanoemulsifying drug delivery systems using N-methyl pyrrolidone as cosolvent

Atorvastatin calcium (ATRC) is a poor water soluble drug used for treatment of hypercholesterolemia. This research is aimed to improve solubility and dissolution rate of ATRC by formulating into solid self-nanoemulsifying drug delivery system (S-SNEDDS) using N-methyl pyrrolidone (NMP) as cosolvent. Solubility of ATRC was determined in various vehicles. Ternary phase diagrams were constructed to identify stable nanoemulsion region. SNEDDS formulations were evaluated for robustness to dilution, thermodynamic stability study, % transmittance, self-emulsification time, globule size and transmission electron microscopy. The optimized liquid SNEDDS showed robust to all dilutions exhibiting no signs of phase separation or precipitation for 24?h. Liquid SNEDDS was transformed into S-SNEDDS using different adsorbents. Differential scanning calorimetry and scanning electron microscopy studies unravel the transformation of native crystalline state to amorphous state/solubilized state. In vitro dissolution study of S-SNEDDS was found to be significantly higher in comparison to that from plain drug, irrespective of pH (p?ex vivo permeation studies showed a 4.45-fold improvement in apparent permeability coefficient (P_app) from S-SNEDDS compared to plain drug. In conclusion, S-SNEDDS prepared using NMP as cosolvent provides an effective approach for improved oral delivery of ATRC.     

Determination and correlation of temperature and pH value dependent solubility of dl-methionine

In order to provide basic data for the crystallization of dl -methionine and understand the thermodynamic properties of dissolution, the solubility of dl -methionine in water was measured by gravimetric method from 294.05 to 347.05 K and the solubility at different pH values under temperature 302.95 to 342.05 K was determined by elemental analysis in this work. The experimental data show that the solubility of dl -methionine increases with increasing temperature as well as more acidic or basic pH values. The van't Hoff equation, modified Apelblat equation, λh equation, Wilson model, NRTL model, and UNIQUAC model were used to correlate the solubility data versus temperature. The melting temperature, enthalpy of fusion, enthalpy and entropy of dissolution were estimated from solubility data and it shows that the expression of solubility by enthalpy and entropy of dissolution gives more reasonable estimation and Wilson model gives a better correlation for these thermodynamic properties.     

Equilibria,kinetics and mechanism for the degradation of the cytotoxic compound L-NG-nitroarginine

L-N^G-nitroarginine (LNNA), an analog of L-arginine, is a competitive inhibitor of nitric oxide synthase which causes the selective reduction of blood flow to tumor cells. Despite the potential of LNNA to function as an adjuvant in cancer therapies, its poor solubility and stability have hindered the development of an injectable formulation of LNNA that is suitable for human administration. This work, for the first time, details a systematic study on the determination of equilibrium K_a constants and the rate law of LNNA degradation. The four K_a values of LNNA were determined to be 1.03, 1.10?×?10^?2, 2.51?×?10^?10, and 1.33?×?10^?13 M. From the kinetic and equilibrium studies, we have shown that the deprotonated form of LNNA is the main form of LNNA that undergoes degradation in aqueous media at room temperature. The rate law of LNNA degradation was found to be first order with respect to OH^? concentration and first order with respect to LNNA^? concentration. The rate constant at 25?°C and 1?atm was determined to be 0.04453 M^?1min^?1. A base catalyzed mechanism of LNNA degradation was proposed based on the kinetic study. The mechanism was found to be very useful in explaining the discrepancies and changes of the rate law at different pH values. It is thus recommended that LNNA should be formulated as a concentrated solution in acidic conditions for maximum chemical stability during storage and be diluted with a basic solution to near physiological pH just before administration.     

Design and Synthesis of Novel Chromophore with Multi-Carboxyl Groups

In order to explore the application of organic conjugated small molecules in bioimaging, a novel functional chromophore with A-π-D-π-A structure (Cr-3) was synthesized through Knoevenagel condensation reaction, consisting of carbazole unit as electron donor and cyanoacetic acid as electron acceptor groups. To improve the water solubility of this conjugated molecule, three carboxyl groups were introduced to chromophore Cr-3. Compared to the traditional D-π-A chromophores, chromophore Cr-3 showed the great improvement in water with the solubility of 2000 ppm. Also, the thermal stability of chromophore Cr-3 was also studied. The thermal decomposition temperature (Td) of Cr-3 was approximately 180°C, which was attributed to the dehydration of the carboxyl groups. Though the second harmonic generation (SHG) effect was not very high, it is large enough for the detection of SHG signal in water solution (0.28 pm/V).     

The quasi ternary system TiB2-CrB2-WB2 between 1900 and 2300°C

The quasi-ternary TiB₂-CrB₂-WB₂ system has been studied up to 2300 °C by means of hot-pressing, SPS and pressureless dilatometry. Liquid phase is generated by two binary eutectics at the TiB₂-WB₂ edge at 2230 ± 30 °C (e₁) and at the CrB₂-WB₂ edge at 1965 °C (e₂). A large homogeneity range of a (Ti,W,Cr)B₂ solid solution has been noticed. A new ternary γ-phase emerges from a critical tie line between (W,Cr,Ti)₂B₄ and α-(Ti,W,Cr)B₂ solid solution at 1950 °C, spreads slightly into both the WB₂ and CrB₂ direction and decomposes by the peritectic reaction P: γ ⇆ α-(Ti,Cr,W)B₂ + (W,Cr,Ti)₂B₄ + Liquid at 2170 ± 30 °C. γ reacts with the CrB₂-WB₂-rich liquid according to the transition equilibrium T: δ-(Ti,Cr,W)B₂ + (W,Cr,Ti)₂B₄ ⇆ γ + Liquid at 2050 °C. The γ-phase is characterized by broad 00 l x-ray reflections which implies a layerwise accumulation and differentiation of Cr and W atoms in the basal plane of the AlB₂-type structure.     

Extruded meat alternatives made from Maillard-reacted beef bone hydrolysate and plant proteins: part I – Effect of moisture content

This study investigated the effects of moisture content (MC) on the physicochemical properties of extruded meat alternatives made from Maillard-reacted beef bone hydrolysate and plant proteins. Samples were extruded at 170 °C (maximum barrel temperature), at 3.6 kg h⁻¹ (liquid feed rate) and at 1.8, 2.2, 2.6 and 3.0 kg h⁻¹ (dry feed rates) to obtain MC of 60%MC, 56%MC, 52%MC and 49%MC, respectively. Meat alternatives at 52%MC showed the greatest degree of texturisation. However, meat alternatives at 49%MC were the closest in terms of both textural and microstructural properties to reference sample, boiled chicken breast. Results from protein solubility suggested that a large amount of aggregated proteins were associated with hydrogen bonds, while disulphide bonds were the main contributor in the formation of fibrous structure in meat alternatives. Results showed that the change in MC as process parameter played an important role in the formation of fibrous structure in extruded meat alternatives.