可降解聚碳酸亚丙酯马来酸酯载药微球的制备

采用阴离子配位聚合方法,合成了二氧化碳(CO2),环氧丙烷(PO)与马来酸酐(MA)的三元共聚物,聚碳酸亚丙酯马来酸酯(PPCMA)。采用复相乳液(W/O/W)溶剂挥发法制备了包裹水溶性模型药物葡萄糖(glucose)的可降解微球,并研究了壁材与囊心的比例、稳定剂明胶浓度、搅拌速率等因素对微球性能的影响。当v(PPCMA)∶v(glucose)=1∶2,gelatin质量分数为0.2%,第1次乳化搅拌速率为400r/min,第2次乳化搅拌速率为500r/min时,得到粒径较小、载药量和包封率分别为26.1%和76.1%的载药微球。

非那雄胺/聚碳酸亚丙酯马来酸酯缓释微球的制备与性能

以新型聚合物聚碳酸亚丙酯马来酸酯(PPCM)为载体,采用Oil/Water单乳液溶剂挥发法制备药物非那雄胺(finasteride)的缓释微球,并研究聚合物PPCM与药物finasteride的质量比对微球特性的影响。研究结果表明:所得PPCM微球外观圆整,平均粒径约为2μm。随着非那雄胺比例的增加,微球的载药量提高,而药物的包封率则明显降低。在m(PPCM):m(finasteride)为5:1的条件下,获得较高的载药量和包封率,分别为14.78%和66.17%。在pH 7.4的磷酸盐缓冲溶液中,载药微球的体外释放时间达42 d,药物累积释放量为(92.59±2.62)%。微球的释药特性符合Higuchi方程Qt=3.11+15.07 t1/2。PPCM适用于长效缓释药物传递系统。

PC/PP/MPP合金体系的力学性能与相态结构

本文介绍以马来酸酐接枝ＰＰ（ＭＰＰ）为相容剂，通过熔融共混的方法制备ＰＣ／ＰＰ合金体系，并研究了配方、力学性能和相态结构之间的关系。由力学性能测试和扫描电镜观察的结果表明，在ＰＣ含量（质量分数，下同）小于５５％时，不含ＭＰＰ样品的冲击强度高于含质量分数（下同）为１０％ＭＰＰ样品的冲击强度；大于５５％时，含１０％ＭＰＰ样品的冲击强度高于同等ＰＣ含量的不含ＭＰＰ样品的冲击强度，其峰值出现在ＰＣ含量为８０％～９０％处。体系拉伸和弯曲强度随ＰＣ含量的变化规律相似，在ＰＣ含量小于５５％时，不含ＭＰＰ样品的拉伸和弯曲强度曲线均出现正峰，而含１０％ＭＰＰ样品出现负峰；当ＰＣ含量大于５５％时，二强度随ＰＣ含量的增加几乎线性地增加，并且含与不含ＭＰＰ样品的变化曲线接近重合。由上述力学性能的变化情况可知，ＭＰＰ对合金的相态结构和力学性能有显著的影响。

三维支架材料与脂肪干细胞的生物相容性

背景:构建组织工程化气管需要适合的三维支架。目的:观察脂肪干细胞与聚乳酸-乙醇酸共聚物及聚三亚甲基碳酸酯共聚物支架的生物相容性。方法:采用组织块法原代分离培养SD大鼠脂肪干细胞,行流式细胞术及多向分化能力鉴定。将脂肪干细胞分别种植于聚乳酸-乙醇酸共聚物和聚乳酸-乙醇酸-三亚甲基碳酸酯共聚物支架中,扫描电镜观察细胞与支架的生物相容性。结果与结论:脂肪干细胞种植于两种支架材料后生长速度快,扫描电镜观察可见脂肪干细胞呈球型,并伸展形成伪足,贴附于支架材料,细胞间相互连接成团。说明聚乳酸-乙醇酸共聚物与聚三亚甲基碳酸酯共聚物支架均具有良好的生物相容性,无细胞毒性,其多孔的三维立体状结构适合脂肪干细胞黏附生长。

Vapor-Liquid Equilibrium Data of Carbon Dioxide＋Methyl Propionate and Carbon Dioxide＋Propyl Propionate Systems

High-pressure vapor-liquid equilibrium data for the binary systems of methyl propionate＋carbon dioxide and propyl propionate＋carbon dioxide were measured at pressure from 1.00 MPa to 12.00 MPa and temperature in the range from 313 K to 373 K. Experimental results were correlated with the Peng-Robinson equation of state with the two-parameter van der Waals mixing rule. At the same time, the Henry＇s coefficient, partial molar enthalpy change and partial molar entropy change of CO2 during dissolution at different temperature were also calculated.

Separation of aluminosilicates and diaspore from diasporic-bauxite by selective flocculation

The flocculation tests of four pure minerals(diaspore,kaolinite,illite,pyrophyllite)and bauxite ore were investigated by the sedimentation.The dispersion behavior of the four pure minerals shows a very good consistency with the variation of zeta potential.The concentrate with the mass ratio of Al2O3 to SiO2(m(Al2O3)/m(SiO2))8.90 and the recovery of Al2O3 86.98%is obtained from bauxite ore(m(Al2O3)/m(SiO2)=5.68)in pH range of 9.5-10.0 by using sodium carbonate(5 kg/t)and sodium polyacrylate(7 g/t)as dispersant and flocculant respectively.Sodium carbonate acts as both pH modifier and favorable dispersant for aluminosilicates.The high performance of sodium polyacrylate on flocculation for diaspore is contributed to the carboxyl of sodium polyacrylate that interacts with active Al sites on diaspore by chemical absorption,and the hydrogen bond effects between hydroxyl group of macromolecule and surface Al—OH on diaspore to accelerate the sedimentation of diaspore.

Preparation of poly （methyl methacrylate）／nanometer calcium carbonate composite by in-situ emulsion polymerization

Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.

Enantioselective synthesis of quaternary α-aminophosphonates by organocatalytic Friedel–Crafts reactions of indoles with cyclicα-ketiminophosphonates

An efficient asymmetric Friedel-Crafts reaction has been developed for the synthesis of optically active quaternaryα‐aminophosphonates with up to98%ee.The synthesis involves the reaction of cyclicα‐ketiminophosphonates with indoles using an H8‐BINOL‐derived chiral phosphoric acid(CPA)catalyst that bears electron‐withdrawing3,5‐ditrifluoromethylphenyl substituents on its3‐and3′‐positions.This Friedel-Crafts reaction of cyclicα‐ketiminophosphonates was also successful with pyrrole.

Simultaneous Synthesis of Dimethyl Carbonate and Poly（ethylene terephthalate） Using Alkali Metals as Catalysts

Dimethyl carbonate （DMC） and poly（ethylene terephthalate） was simultaneously synthesized by the transesterification of ethylene carbonate （EC） with dimethyl terephthalate （DMT） in this paper. This reaction is an excellent green chemical process without poisonous substance. Various alkali metals were used as the catalysts. The results showed alkali metals had catalytic activity in a certain extent. The effect of reaction condition was also studied. When the reaction was carded out under the following conditions： the reaction temperature 250℃, molar ratio of EC to DMT 3 ： 1, reaction time 3h, and catalyst amount 0.004 （molar ratio to DMT）, the yield of DMC was 68.9%.

Polycarbonate/Polypropylene/Fibrillar Silicate Ternary Nanocomposites via Two-step Blending Process: Degradation and Morphology

The method of two-step melt blending was used to prepare polycarbonate/polypropylene/attapulgite ternary nanocomposite, and the various techniques including gel permeation chromatography, rheometer, transmis- sion electron microscope, dynamic mechanical analysis were used to examine the degradation of polycarbonate (PC) and the nanocomposite morphology. The results showed that the molecular weight degradation of PC triggered by attapulgite (AT) during the direct blending process was inhibited effectively by using two-step melt blending, in which AT was blended with polypropylene (PP) prior to compound with PC. The morphology of encapsulation was formed in the PC matrix, where PP encapsulates AT fibrillar single crystals to form a core-shell inclusion. Dynamic mechanical analysis (DMA) measurements showed that the PC/PP/AT ternary nanocomposites were more effective than conventional PC/PP blends in reinforcement, meanwhile the addition of AT in the ternary nanocomposites shifted the glass transition temperature of the PP phase to a higher value.

Heterogeneous synthesis of dimethylhexane-1,6-dicarbamate from 1,6-hexanediamine and methyl carbonate in methanol over a CeO_2 catalyst

The efficient synthesis of dimethylhexane-1,6-dicarbamate(HDC)from 1,6-hexanediamine(HDA)and methyl carbonate over a series of heterogeneous catalysts(e.g.,Mg O,Fe2O3,Mo2O3,and Ce O2)was investigated.The reaction pathway was confirmed as an alcoholysis reaction through a series of designed experiments.Under optimized conditions,100%HDA conversion with 83.1%HDCtotaland 16.9%polyurea was obtained using a onestep with high temperature procedure with Ce O2as the catalyst.A new two-step with variable temperature technology was developed based on the reaction pathway to reduce the polyurea yield.Using the proposed method,the HDCtotalyield reached 95.2%,whereas the polyurea yield decreased to 4.8%.The Ce O2catalyst showed high stability and did not exhibit any observable decrease in the HDC yield or any structural changes after four recycling periods.

Efficient synthesis of 1,6-hexamethylene diurethane through coupling transesterification and methoxycarbonylation with methyl phenyl carbonate as intermediate

A reaction coupling system of transesterification and methoxycarbonylation with methyl phenyl carbonate （MPC） as intermediate was established to efficiently prepare 1,6-hexamethylene diurethane （HDU） from 1,6- bexametbylene diamine （HDA）. The feasibility of the system was explored using the thermodynamics analysis, the reaction mechanism and the experiment results. The optimal reaction was carried out to get higher HDU yield. The thermodynamic analysis showed that the metboxycarbonylation of HDA with MPC, the Gibbs free energy of which was negative, was a spontaneous process. Furthermore, the equilibrium constant of the methoxycarbonylation of HDA with MPC was much greater than that of the transesterification of dimethyl carbonate （DMC） with phenol, so the reaction coupling could be realized under mild conditions. The reaction mechanism analysis indicated that phenoxy anion was the key spedes for reaction coupling. Higher MPC concentration was detected when sodium phenoxide was used as transesterification reactant with DMC, since the phenoxy anion of sodium phenoxide could be dissociated more easily. Sodium pbenoxide was more suitable to prepare HHDU through reaction coupling. A yield of HDU as high as 98.3% could be reached under the optimal conditions of mPhONa/mDMC = 0.027 and nDMC/nHDa = 8/1 at 90 ℃ in 2 h.

Synthesis of dimethyl adipate from cyclopentanone and dimethyl carbonate over solid base catalysts

A facile route for the synthesis of dimethyl adipate （DAP） from cyclopentanone and dimethyl carbonate （DMC） in the pres- ence of solid base catalysts has been developed. It was found that the intermediate carbomethoxycyclopentanone （CMCP） was produced from cyclopentanone with DMC in the first step, and then CMCP was further converted to DAP by reacting with a methoxide group. The role of the basic catalysts can be mainly ascribed to the activation of cyclopentanone via the abstraction of a proton in the a-position by base sites, and solid bases with moderate strength, such as MgO, favor the formation of DAP.

Ordered mesoporous Ba CO_3/C-catalyzed synthesis of glycerol carbonate from glycerol and dimethyl carbonate

Ordered mesoporous BaCO3/C composites were synthesized by a multi-component co-assembly method combined with a carbonization process using phenolic resol as carbon source, barium nitrate as barium precursor, and triblock copolymer Pluronic F127 as template. The synthesized materials were characterized by X-ray diffraction, transmission electron microscopy, N2 physical adsorption, thermogravimetric analysis, and temperature-programmed desorption of CO〉 When BaCO3 contents were increased from 9.1 wt% to 44.7 wt%, pore size increased from 3.1 to 4.3 nm and the BET （Brunauer-Emmett-Teller） surface area initially increased to a maximum value of 390 m2 g^-1 （at a BaCO3 content of 18.5 wt%） before subsequently decreasing. BaCO3 was well dispersed in the amorphous carbon framework, and no phase separation was observed. The mesoporous BaCO3/C composites exhibited high catalytic activities toward the transesterification of glycerol and dimethyl carbonate into glycerol carbonate. A glycerol conversion of 97.8% and a glycerol carbonate selectivity of 98.5% were obtained under the optimized reaction conditions.

Generating strongly basic sites on magnetic nano-stirring bars:Multifunctional integrated catalysts for transesterification reaction

Mass transfer and catalyst recovery are two crucial issues in solid base catalysis,while the cumbersome operation steps and the associated time and energy penalties are still inevitable for conventional catalysts.Achieving the technical upgrades through catalyst design is desirable but challenging because of the difficulty in satisfying diverse demands of different steps.In this work,a magnetically responsive solid base catalyst with the rod-like nanostructure was developed.The rod-like solid base catalysts are composed of Fe_(3)O_(4) cores,silica shells and calcium oxide active sites.The functions of magnetic recovery and stirring were integrated into the catalyst,which applies in both the general catalytic processes and microchannel reactors given their nanoscales.When applied to the synthesis of dimethyl carbonate by onestep transesterification of methanol and ethylene carbonate,an apparent enhancement on turnover frequency value(33.1 h^(−1))was observed for nano-stirring compared with that tested without stirring(12.1 h^(−1))within 30 min.The present catalysts may open up new avenues in the development of advanced solid base catalysts.

Early dolomitisation of the Lower-Middle Ordovician cyclic carbonates in northern Tarim Basin, NW China

High-frequency metre-scale cycles are present within the Lower-Middle Ordovician carbonate successions in northern Tarim Basin, NW China. These metre-scale cycles were variably dolomitised from top to bottom. Three types of replacive dolomites were recognised, including dololaminite(very finely to finely crystalline, planar-s to nonplanar-a dolomite;type-1), patterned dolomite(finely crystalline, planar-s dolomite; type-2), and mottled dolomite(finely to medium crystalline,nonplanar-a(s) dolomite; type-3). Petrographic evidence indicate these dolomites were primarily deposited in supratidal to restricted subtidal environments, and formed in near-surface to shallow burial realms. Geochemically, all types of dolomites have similar δ13C and 87Sr/86 Sr ratios comparable to calcite precipitated in equilibrium with the Early-Middle Ordovician seawater. These geochemical attributes indicate that these dolomites were genetically associated and likely formed from connate seawater-derived brines. Of these, type-1 dolomite has δ18O values(.4.97‰ to.4.04‰ VPDB) slightly higher than those of normal seawater dolomite of the Early-Middle Ordovician age. Considering the absence of associated evaporites within type-1 dolomite, its parental fluids were likely represented by slightly evaporated(i.e., mesosaline to penesaline) seawater with salinity below that of gypsum precipitation. More depleted δ18O values(.7.74‰ to.5.20‰ VPDB) of type-2 dolomite and its stratigraphic position below type-1 dolomite indicate the generation of this dolomite from mesosaline to penesaline brines at higher temperatures in near-surface to shallow burial domains. Type-3 dolomite yields the most depleted δ18O values(–9.30‰to –7.28‰ VPDB), pointing to that it was most likely formed from coeval seawater-derived brines at highest temperatures in a shallow burial setting. There is a downward decreasing trend in δ18O values from type-1 through type-2 to type-3 dolomites, and in abundance of dolomites, indicating that the dolomitising fluids probably migrated downward from above and persisted into shallow burial conditions.