查找使用阿拉丁产品的科研文献

Determination and analysis of solubility of brassinolide in different solvent systems at different temperatures (T = 278.15–323.15 K)

Zilong Cui,Zhiruo Zhao,Liang Yao,Yonghong Hu

Brassinolide is a new environmental protection plant growth regulator. With the aim of knocking down selfcost and scale up agriculture market-place emulation, come what will manufacture method is adopted, the final step crystallization is significant for getting exclusive substances. The purpose of this study is to provide some authentic and general energetics data for the actual industrial production of brassinolide. In the research, the solid–liquid equilibrium of brassinolide in twelve pure solvents (tetrahydrofuran, dimethyl sulfoxide, ethanol, acetone, methanol, trichloromethane, acetonitrile, 1-butanol, isopropanol, xylenes, n-hexane and n-heptane) and three binary solvent mixtures (trichloromethane + tetrahydrofuran, acetonitrile + tetrahydrofuran and n-hexane + tetrahydrofuran) were tested by the circumstance of atmosphere pressure at range temperatures between 278.15 K and 323.15 K. Four models like the Buchowski–Ksiazaczak λh model, the modified Apelblat model, the Jouyban-Acree-van't-Hoff model and the Redich-Kister (CNIBS/R-K) model were employed to describe the change trend of solubility. On the groundwork of a series of data analysis, tetrahydrofuran is a better organic solvent and n-hexane can be applied as an effective anti-solvent when separating out brassinolides. These solubility data are very important for optimizing the extraction process and recrystallization of brassinolide.

Solubility determination and dissolution thermodynamic properties of dodecanedioic acid in binary-mixed solvents from T = (288.15–328.15) K

Shuo Cheng,Yu Bao,Yue Cui,Jingtao Wang

In this paper, the solubility and dissolution thermodynamic properties of dodecanedioic acid (DDDA) in four binary-mixed solvents (ethyl acetate + ethanol, ethyl acetate + acetic acid, and ethyl acetate + acetone) were investigated. The gravimetric method was employed to determine the mole fraction solubility of DDDA in different solvent ratios from 288.15 K to 328.15 K under the atmosphere. In the binary solvents of ethyl acetate + ethanol and ethyl acetate + acetic acid, when the composition was varied the solubility change was not monotonous, and the phenomenon of co-solvency occured. Furthermore, four models were employed to fit the solubility data, among which the modified Apelblat equation and CNIBS/R-K model had better fitting results. Finally, the dissolution thermodynamic properties of DDDA were analyzed based on the modified Van’t Hoff equation.

Solid–Liquid Phase Equilibria of the Ternary System (KBO2 + K2SO4 + H2O) at 288.15, 308.15 K, and 0.1 MPa

Fei Yuan,Hua Li,Long Li,Yafei Guo,Shiqiang Wang,Tianlong Deng

Considering the significance of fundamental phase equilibrium data in resource exploitation from salt lake brines, the solid–liquid phase equilibria of the ternary system (KBO2 + K2SO4 + H2O) at 288.15, 308.15 K, and 0.1 MPa were investigated using the isothermal dissolution method. Along this line, the solubilities and physicochemical properties of densities were experimentally determined. Based on the experimental data, phase diagrams and the related physicochemical property diagrams against composition were plotted. It was found that there are one invariant point, two univariate solubility curves, and two crystalline regions corresponding to potassium metaborate hydrate (KBO2·1.33H2O) and arcanite (K2SO4) in the ternary phase diagrams at 288.15 and 308.15 K. In addition, they belong to the hydrate type I and neither double salt nor solid solution was formed. The distributive behaviors of density against the concentration of KBO2 in the equilibrium solution at two temperatures were similar. Moreover, the theoretical values of density were calculated, which were found to be consistent with the experimental values, further demonstrating the accuracy and reliability of this work.

Intrinsic high-k–low-loss dielectric polyimides containing ortho-position aromatic nitrile moieties: reconsideration on Clausius–Mossotti equation

Tianwen Zhu,Qiaoxi Yu,Weiwen Zheng,Runxin Bei,Wenhui Wang,Minming Wu,Siwei Liu,Zhenguo Chi,Yi Zhang,Jiarui Xu

The precision regulation of the dielectric polarization and dielectric loss of polymer materials, developing intrinsic high-performance polymers with high dielectric constant, low dielectric loss and excellent temperature resistance is very challenging. In this work, a facile molecular design strategy was developed by directly introducing two ortho-position aromatic nitrile groups into the rigid polyimide backbone. Compared with similar polyimides without nitrile groups (0CN-PIs), the polarizability and dielectric constant of the designed polyimide (2CN-PIs) can be greatly increased. Meanwhile, the polarization motions of the nitrile groups can be limited at room temperature, which is beneficial to lowering the dielectric loss. Among the designed polyimides, 2CN-BTDA shows a high k value of 4.80, low dielectric loss of 1.57 × 10−3 at 1 kHz (25 °C), and breakdown strength of 219.4 kV mm−1 with high maximum discharge energy density of 1.023 J cm−3. Moreover, its Tg value is as high as 325 °C, much higher than that of most traditional dielectric polymers. The essence of designing high-k–low-loss intrinsic polymers was revealed by reconsidering the Clausius–Mossotti equation, where the total polarizability should be maximized while the chain stacking should be as tight as possible; that is, a rigid polymer backbone, small sized polar groups (like nitrile groups), and a spatial position in favor of orientation polarization are preferred. The results are helpful to promote the research progress of dielectric polarization and of great significance to the development of high-performance high-k–low-loss dielectric materials for potential applications in modern electronic information and microelectronic industry.

Solubility Measurement and Model Correlating of 6-Propyl-2-Thiouracil in Four Binary Solvents at 278.15–323.15 K

Wenju Liu,Yanmin Shen,Fankun Zeng,Shuanghui Lu,Jun Li,Jinjin Yang,Kewen Zhang

The solubility of 6-propyl-2-thiouracil was determined in DMF + water, DMF + methanol, DMF + ethanol, and DMF + 1-propanol mixture solvents by a gravimetric method in the temperature range from 278.15 to 323.15 K under atmospheric pressure. The results indicated that the solubility of 6-propyl-2-thiouracil in the (DMF + methanol) mixture is greater than that in (DMF + ethanol), (DMF + 1-propanol), and (DMF + water) at the same DMF composition and temperature, and that the solubility increased with increase in the mass fraction of DMF in mixture solvents. The modified Apelblat model, λh model, Van′t Hoff model, and Jouyban Acree-Apelblat model were employed to correlate well with the solubility of 6-propyl-2-thiouracil in four binary solvents using values of ARD% and RD, and the four models were considered to be the reliable methods for the solubility prediction of 6-propyl-2-thiouracil.

High performance low-k and wave-transparent cyanate ester resins modified with a novel bismaleimide hollow polymer microsphere

Wenxing Jiang,Xianhong Zhang,Dong Chen,Yuhong Ma,Wantai Yang

High-performance cyanate ester (CE) resins with excellent dielectric properties are highly desired in the fields of information and communication technology . Herein, we present an efficient strategy for the preparation of low- k and wave-transparent CE resins modified with a novel kind of bismaleimide (BMI) hollow polymer microspheres (BMI-HPPs). Benefiting from both the superior properties of BMI and the unique hollow structure, BMI-HPPs can serve as an effective modifier to reduce dielectric constant (ε) of the CE resins and simultaneously improve their toughness. There are plenty of pendant vinyl groups and unreacted maleimide groups on the surface of BMI-HPPs, which could effectively copolymerize with CE monomer , leading to a lower curing temperature and better interfacial compatibility. The BMI-HPPs/CE resin with 7.5 wt% BMI-HPPs exhibited minimum values of ε and dielectric loss (tanδ) (2.46, 0.006) at 16 GHz, much lower than those of the pristine CE resin (2.92, 0.018), and the corresponding wave transmission was 93.8%–97.1% in the frequency range of 15–18 GHz. Moreover, the modified CE resin showed a maximum impact strength of 18.8 kJ/m 2 at 5 wt% loading of BMI-HPPs, which is 64% higher than that of the pristine CE resin. Because of low- k dielectric properties, superior wave-transparent performance and highly enhanced toughness , the BMI-HPPs/CE resins have great potential in the fields of microelectronics and aerospace.

A green approach for enhancing the hydrophobicity of UiO-66(Zr) catalysts for biodiesel production at 298 K

Ahmed S. Abou-Elyazed,Yinyong Sun,Ahmed M. El-Nahas,Ahmed M. Yousif

Recently, the incorporation of hydrophobicity on the surface of UiO-66(Zr) has received much attention due to the deactivation of hydrophilic active sites of UiO-66(Zr) upon water adsorption. In this work, we report UiO-66(Zr) catalysts with an assortment of surface hydrophobicities fabricated by the solvent-free method to elucidate the impact of the environment framing Lewis acid sites on their catalytic activity in the production of fatty acid methyl ester (biodiesel) via the esterification of fatty acids at room temperature with high selectivity (100%) and good recyclability. A detailed structural analysis of the materials by N2 sorption, FT-IR, SEM, XRD, water contact angle measurement, dynamic liquid scattering (DLS), NMR and TGA revealed the fabrication of stearic acid-grafted UiO-66(Zr) catalysts (10SA/UiO-66) with fine particle size and a highly hydrophobic network. 10SA/UiO-66(Zr) with enhanced hydrophobicity exhibited superior catalytic performance in the esterification of a fatty acid with a long alkyl chain compared with conventional solid acid catalysts and even liquid acid catalysts. Detailed kinetic studies corroborated that the adsorption of lipophilic acids at the Lewis acid sites besides the enhancement of wettability between the reactants was facilitated by the hydrophobic environment, thus significantly motivating the esterification reaction at room temperature. Furthermore, 10SA/UiO-66(Zr) showed good catalytic activity in the esterification of oleic acid in the presence of water (∼10% in the light of acid weight).

Na3AMg7(PO4)6 (A = K, Rb and Cs): Structures, properties and theoretical studies of alkali metal magnesium orthophosphates

Jiahao Jiao,Wenqi Jin,Min Zhang,Zhihua Yang,Shilie Pan

Phase Equilibria and Phase Diagrams of the Li+, Na+//Cl–, CO32––H2O System at 323.15 and 348.15 K

Kuo Zhou,Xingfan Wang,Junfang Yang,Fenli Jin,Huan Zhou

The solubility equilibrium of Li+, Na+//Cl–, CO32– −H2O quaternary systems at 323.15 K and 348.15 K was studied via the isothermal solubility equilibrium method, and the complete phase diagrams were obtained including the properties of liquid density and pH. Solid species of LiCl·H2O, Li2CO3, NaCl, and Na2CO3·H2O are found in the quaternary system at 323.15 K and 348.15 K, and one double salt of Li2CO3·Na2CO3 is found at 348.15 K. The liquid phase of two invariant points and five univariant curves at 323.15 and three invariant points and seven univariant curves at 348.15 K in the quaternary system is determined. Li2CO3 covers the largest solid phase region and is hardly influenced by temperature; Li2CO3–NaCl is a stable salt pair, and its cosaturated solubility is the least at the diagonal line of Li2CO3–NaCl.

Permeability of N, P, K-fertilizer nutrient and water vapor through PLA, PLA/PS, and PLA/HA membranes

Xiaonan Deng,Sihong Ye,Kun Liu,Changfeng Li,Fangzhi Liu,Xiaoming Yan

To collect permeability data and establish its database of fertilizer nutrients and water vapor through different polymer membranes for the development of polymer-coated fertilizer, the permeabilities of N-, P-, and K-nutrient from saturated aqueous of urea, NaH2PO4 and KCl solution and the permeability of water vapor through the membranes of poly lactic acid (PLA), its blends with polystyrene (PS), and its composites with humic acid (HA) particles were determined experimentally at the temperatures of 288, 298, and 308 K, respectively. The effects of the addition of PS and HA particles, temperature, and coating thickness on the permeability of fertilizer nutrient and water vapor were investigated. It was found that the addition of PS and HA increased the permeability for both the fertilizer nutrients and water vapor. The increase in temperature raised the permeability of N-, P-, and K-nutrient while decrease the permeability of water vapor in the range studied.

Cage-like P4S3 molecule as promising anode with high capacity and cycling stability for Li+/Na+/K+ storage

Denghu Wei,Jie Yin,Zhicheng Ju,Suyuan Zeng,Haibo Li,Wei Zhao,Yanyan Wei,Huaiyong Li

Phosphorus sulfide cage molecule based on P 4 S 3 was investigated for the first time as anode material for the storage of alkali metal ions (Li + , Na + , K + ). Such P 4 S 3 sample was obtained in a large scale by a simple heating reaction of low-cost rep P and S. X-ray diffraction refinement analysis indicates that P 4 S 3 sample possesses a defect rich molecule crystal structure with S/P atom ratio of 0.74. The P 4 S 3 anode delivered a high reversible capacity of 1266 mAh g −1 for lithium-ion batteries at 0.1 A g −1 and good cycling performance. Experimental results demonstrated that the P 4 S 3 anode undergoes a reversible Li-storage reaction of P 4 S 3  + 11 Li +  + 11 e − ↔ 0.5 Li 4 P 2 S 6  + 3 Li 3 P during cycling. It also exhibited a high capacity of 1002 and 378 mAh g −1 at 0.1 A g −1 for Na + and K + storage, respectively. These properties suggest the promising application of P 4 S 3 anode in high energy batteries.

Solubility Measurement and Correlation of Doxycycline Hyclate in 10 Pure Solvents and Mixtures Solvents at 278.15–323.15 K

Yanmin Shen,Wenju Liu,Chen Sun,Paifeng Shi

The solid–liquid phase equilibrium solubility of doxycycline hyclate (DH) in 10 pure organic solvents and cosolvent mixtures DMF (1) + ethanol (2), DMSO (1) + ethanol (2) and acetone (1) + ethanol (2) at a temperature range from 278.15 to 323.15 K was measured and discussed. The results indicated that the experimental mole fraction (x) of DH in 10 neat solvents followed this order: acrylic acid > acetic acid > 1-butanol > 1-pentanol > tetrahydrofuran > isobutyl alcohol > isopropyl alcohol> propanoic acid > acetone > acetonitrile, and temperature affected obviously the solubility especially in acetic acid. Moreover, the experimental mole fraction (x) of DH increased with mass concentration rising of DMF or DMSO in DMF (1) + ethanol (2) or DMSO (1) + ethanol (2), and decreased gradually with mass concentration rising of acetone in acetone (1) + ethanol (2). The experimental solubility in all solvents was correlated better by the modified Apelblat model according to lower values of RAD and RMSD.