Achieving highly crystalline rate and crystallinity in Poly(l-lactide) via in-situ melting reaction with diisocyanate and benzohydrazine to form nucleating agents

The drawback of the application for poly(_l-lactide) (PLLA) is the low crystalline rate and crystallinity obtaining via normal processing methods. Modifying crystallization of PLLA has been found to be an efficient way to improve its mechanical and heat resistance properties. In this wok, 4, 4′-diphenylmethane diisocyanate (M) and benzohydrazine (P) were employed into PLLA melt to in-situ form nucleating agents. The in-situ melting reaction was confirmed by a nuclear magnetic resonance spectroscopy. The crystallization behavior and crystalline morphology were investigated by a differential scanning calorimetry, a polarized optical microscopy and a field emission scanning electron microscope. The crystalline rate of PLLA was abruptly enhanced by adding (M+P) and melting reaction with PLLA. The crystallization half-time of PLLA dramatically decreased from 42.0 to 1.1 min at 130 °C by the in-situ formation of nucleating agents. The crystallinity of PLLA increased from 10.3 to 42.1 by adding 0.25% (M+P) and melting reaction for 8 min. Furthermore, the size of PLLA crystals was dramatically reduced because of the nucleating effect. Accompanied with improvement on crystallinity, the Vicat softening temperature of PLLA shifted from 57.4 °C to 93.7 °C by the in-situ reaction with 6.00% (M+P), and indicating heat resistance enhancement.     

Simultaneous determination of atropine,scopolamine, and anisodamine from Hyoscyamus niger L. in rat plasma by high‐performance liquid chromatography with tandem mass spectrometry and its application to a pharmacokinetics study

In order to investigate the pharmacokinetics of tropane alkaloids in Hyoscyamus niger L., a sensitive and specific high‐performance liquid chromatography with tandem mass spectrometry method for the simultaneous determination of atropine, scopolamine, and anisodamine in rat plasma is developed and fully validated, using homatropine as an internal standard. The separation of the four compounds was carried out on a BDS Hypersil? C₁₈ column using a mobile phase consisting of acetonitrile and water (containing 10 mmol ammonium acetate). Calibration curves were linear from 0.2 to 40 ng/mL for atropine, scopolamine, and from 0.08 to 20 ng/mL for anisodamine. The precision of three analytes was <5.89% and the accuracy was between ?1.04 to 2.94%. This method is successfully applied to rat pharmacokinetics analysis of the three tropane alkaloids after oral administration of H. niger extract. The maximum concentration of these three tropane alkaloids was reached within 15 min, and the maximum concentrations were 31.36 ± 7.35 ng/mL for atropine, 49.94 ± 2.67 ng/mL for scopolamine, and 2.83 ± 1.49 ng/mL for anisodamine. The pharmacokinetic parameters revealed areas under the curve of 22.76 ± 5.80, 16.80 ± 3.08, and 4.31 ± 1.21 ng/h mL and mean residence times of 2.08 ± 0.55, 1.19 ± 0.45, and 3.28 ± 0.78 h for atropine, scopolamine, and anisodamine, respectively.     

润湿剂促进燃煤细颗粒声波团聚脱除的实验研究

在声波团聚室中研究了润湿剂液滴与细颗粒碰撞团聚脱除特性,提出了一种利用润湿剂促进细颗粒在声波场中捕集的新方法。结果表明,不同润湿剂溶液对细颗粒在声波场中的团聚脱除效果存在较大差异,采用JFC和FS-310润湿剂溶液时,细颗粒分级脱除效率与采用水时的分级脱除效率相近。而SDS和Silanol w22溶液,则可有效提高细颗粒在各粒径段的分级脱除效率。细颗粒在声波场中的脱除效率与润湿剂润湿性能具有很好的相关性,随润湿剂对细颗粒相对接触角增大而降低,在声压级为150 dB时,相对接触角由83°降低到0°,细颗粒脱除效率提高了18%,在无声场作用下,脱除效率仅提高了5%。细颗粒脱除效率随声压级的增大而提高,在低声压级条件下,添加润湿剂可有效提高细颗粒脱除效率,声压级在130 dB时,添加SDS溶液液滴后细颗粒脱除效率比声场单独作用时的脱除效率提高了25%。表明添加润湿剂可有效提高细颗粒在声波场中的团聚脱除效率,实现在低声压级条件下,获得高的细颗粒脱除效率。     

以四甲基铵硅酸盐为柱化剂合成层柱状MCM-36分子筛

以层状MCM-22P为前驱体,四甲基铵硅酸盐为柱化剂,采用动态水热法考察了MCM-36分子筛的合成条件,并通过XRD、N2物理吸附、TEM、27Al-MAS NMR以及NH3-TPD等手段对合成分子筛进行了表征。结果表明,与传统的采用正硅酸乙酯为柱化剂的柱化过程相比,以四甲基铵硅酸盐为柱化剂时,已溶胀的前驱体不经干燥处理即可直接在含水体系进行柱化插层合成得到层间距均一的层柱状MCM-36分子筛,适宜的合成条件为:先在80℃的高pH值(约13.5)环境下对前驱体溶胀24 h,然后在100℃下柱化插层24 h。表征结果表明,MCM-36分子筛具有层内微孔和层间介孔的复合孔道结构以及较大的比表面积(特别是外比表面积);与HMCM-22相比,HMCM-36的表面酸性虽明显降低,但其层间介孔结构的形成使大量B酸中心暴露于大分子易于接近的层间介孔孔壁,可为涉及较大分子的催化反应提供更多可接近的活性位中心。     

DNA gel particles: An overview

A general understanding of interactions between DNA and oppositely charged compounds forms the basis for developing novel DNA-based materials, including gel particles. The association strength, which is altered by varying the chemical structure of the cationic cosolute, determines the spatial homogeneity of the gelation process, creating DNA reservoir devices and DNA matrix devices that can be designed to release either single- (ssDNA) or double-stranded (dsDNA) DNA. This review covers recent developments on the topic of DNA gel particles formed in water–water emulsion-type interfaces. The degree of DNA entrapment, particle morphology, swelling/dissolution behavior and DNA release responses are discussed as functions of the nature of the cationic agent used. On the basis of designing DNA gel particles for therapeutic purposes, recent studies on the determination of the surface hydrophobicity and the hemolytic and the cytotoxic assessments of the obtained DNA gel particles have been also reported.     

Development of BINOL-Si complexes with large stokes shifts and their application as chemodosimeters for nerve agent

Three fluorescent BINOL-Si complexes (FS1, FS2 and FS3) were rationally designed and synthesized to detect diethyl chlorophosphate (DCP), a mimic of lethal nerve agents. These three fluorescent probes showed green, yellow and orange fluorescence, respectively. Moreover, the series of fluorescent probes has the characteristics of fast response time (≤ 4 s), low detection limit (0.0097 μmol/L), high sensitivity and naked eye detection. More important, a fiber optic sensor capable of detecting DCP vapor in real time was also prepared for the first time, the lowest detection limits (down to 4.4 ppb) were all lower than that of the IDLH (immediately dangerous to life or health) concentration of Sarin (7.0 ppb).     

聚吡咯及其纳米复合材料在光热治疗领域的应用

光热治疗是近年来兴起的一种治疗方法,具有靶向性强、适应性广的特点。在光热治疗中,通过光热剂对光的吸收将光能转化为热能,从而实现治疗作用,因而光热剂的光热转化性能直接决定了光热治疗的效果。光热剂的种类丰富,涵盖由无机到有机等组成和性能各异的多种材料。其中,聚吡咯具备良好的生物相容性、优异的光稳定性以及光热转化性能,在光热治疗领域受到广泛关注,是一种拥有巨大应用潜力的光热剂,然而其在光热治疗领域的发展趋势及前景却鲜有报道。本文综述了聚吡咯及其纳米复合材料的制备方法,详述了聚吡咯及其纳米复合材料在光热治疗领域中的应用情况,包括聚吡咯基纳米材料的自身性能和实际光热治疗的效果,指出以聚吡咯为基体或修饰材料来制备具有CT、磁共振、光声显影及光热治疗性能的聚吡咯基复合材料已成为发展趋势。在此基础上,本文还总结了聚吡咯基纳米复合材料在制备和应用中存在的问题,并分析了其在发展过程中遇到的挑战以及在生物医学应用中的前景。     

Thermal stability and dynamic mechanical thermal analysis of epoxy thermosets possessing N,N′-disubstituted pyromellitimide units

Abstract

In this work, three epoxy resins including diglycidyl ethers of N,N′-bis(2-hydroxyethyl)pyromellitimide (DIDGE), bisphenol-A (BADGE), and polyethylene glycol (PEDGE) were isothermally cured by an amine curing agent possessing N,N′-disubstituted pyromellitimide units (denoted by DIDAM). DIDGE resin was synthesized from the reaction of N,N′-bis(2-hydroxyethyl)pyromellitimide with an excess of epichlorohydrin. Also, DIDAM curing agent was prepared from the reaction of pyromellitic dianhydride with an excess of ethylene diamine. Completion of the isothermal curing processes was approved by both Fourier transform-infrared spectroscopy and non-isothermal differential scanning calorimetry (DSC). The DSC traces showed only the phase transitions related to the thermal degradation of the resulting thermosets. According to the thermogravimetric analyses, the DIDGE/DIDAM thermoset showed higher thermal stability at temperatures above 425?°C than the other two thermosets. While BADGE/DIDAM and PEDGE/DIDAM thermosets showed about 70% weight loss in the thermal range of 400–850?°C, DIDGE/DIDAM thermoset was encountered with only about 40% weight loss. The glass transition temperatures (T_g ) of the resulting thermosets were determined using tan δ vs temperature plots obtained from dynamic mechanical thermal analysis. The T_g values of BADGE/DIDAM, DIDGE/DIDAM, and PEDGE/DIDAM thermosets were found to be 211?°C, 189?°C, and 81?°C, respectively.     

Effects of a novel ultrasound contrast agent with long persistence on right ventricular pressure: Comparison with SonoVue

This work investigated the effect of infusion of a self-made ultrasound contrast agent with long persistence (named ZHIFUXIAN) on rat right ventricular pressure and made a preliminary evaluation on the relative safety of the novel microbubbles. Normal saline, SonoVue and ZHIFUXIAN were injected through caudal vein at the total volume of 0.5 ml for each injection. The right ventricular systolic pressure (RVSP) and end-diastolic pressure (RVEDP) were monitored and the changes of the pressure were compared with baseline readings. RVSP increased when saline, SonoVue or ZHIFUXIAN were injected, the greatest change being after SonoVue (about 2 mm Hg), but there was no statistical significance compared with baseline (P > 0.05). There was no significant difference in RVSP between saline, SonoVue and ZHIFUXIAN at any time point. Also, there was no significant difference in RVEDP between groups at each time point and between different time points in each group. The results indicate that the self-made microbubbles effect on right ventricular hemodynamics is equivalent to that of normal saline at the same volume needed for effective enhanced imaging, demonstrating that it does not produce changes in right ventricular blood pressure under the study conditions. Pathological examination also showed it had no obvious influence on lung, liver and kidney.     

Superhydrophilic porous TiO2 film prepared by phase separation through two stabilizers

A novel method was developed to produce a TiO₂ film with circular pores on its surface. The pores aroused from the precursor solution using both acetylacetone (AcAc) and diethanolamine (DEA) as stabilizers. The appearance of interconnected or isolated pores for the films was discussed in relation to the phase separation in the sol-gel process with the presence of Acac and DEA. Macropore size, together with connectivity of pores and gel skeleton, can be controlled by selecting an appropriate composition for preparation at DEA amount or regulating a time scale of the sol-gel transition. Finally, wetting behavior of the resulting films was characterized by using contact angle measurements. The TiO₂ films with interconnected or relatively isolated pores exhibit superhydrophilic characteristic, although it is not exposed to ultraviolet irradiation. Deducing from the Wenzel-Cassie regimes’ transition criterion, the existence of Cassie impregnating wetting regime rather than Wenzel one upon these porosity-driven superhydrophilic surfaces can be obtained.