Intercalation of lecithins for preparation of layered nanohybrid materials and adsorption of limonene

The intercalation of biosurfactants (lysolecithin and lecithin) in layered clay mineral supports was investigated to assess the suitability of the resulting nanohybrid materials as flavor and fragrance delivery system. The protonated biosurfactant molecules (pH = 2.3) were intercalated into the Na-montmorillonite, whereas the deprotonated biosurfactants (pH ~ 12) were intercalated into Mg–Al layered double hydroxides. The amount of lysolecithin and lecithin bound to the layered adsorbents was estimated by measuring adsorption isotherms. The basal spacing obtained from X-ray diffraction measurements suggested that the molecules are arranged in parallel with the layers of montmorillonite, whereas in the case of layered double hydroxides, the adsorbed molecules are in a vertical position between the layers. The interaction of layered adsorbents and biosurfactants was further evidenced by infrared spectroscopy. The intercalated montmorillonite and LDH particles were then probed for their ability to intercalate limonene molecules. Only the lysolecithins modified samples adsorbed limonene. The theoretical sizes of molecules and their possible arrangement between the layers were modeled by HyperChem 7.0 molecular calculations to correlate the ability to bind the lecithins in the confined space of the layered materials.     

LED用双组分有机硅封装材料的制备与性能研究

以不含苯基的甲基乙烯基硅油(PMVS)和支链型低含氢硅油(PMHS)为主要原料,添加了甲基乙烯基硅树脂(MQ)、稀释剂及硅烷偶联剂(KH-570)等,在铂金水催化剂作用下合成了双组分有机硅封装材料。研究结果表明:由最佳工艺制备的LED封装材料具有较好的热稳定性,并且其在可见光区700 nm处的透光率超过95%;当n(Si—H)∶n(Si—Vi)=1.25∶1、w(MQ)=15%(相对于封装材料质量而言)时,该LED封装材料的综合性能相对最佳。     

Efficient biocatalyst by encapsulating lipase into nanoporous gold

Lipases are one of the most important biocatalysts for biotechnological applications. Immobilization is an efficient method to increase the stability and reusability of lipases. In this study, nanoporous gold (NPG), a new kind of nanoporous material with tunable porosity and excellent biocompatibility, was employed as an effective support for lipase immobilization. The pore size of NPG and adsorption time played key roles in the construction of lipase-NPG biocomposites. The morphology and composition of NPG before and after lipase loading are verified using a scanning electron microscope, equipped with an energy-dispersive X-ray spectrometer. The resulting lipase-NPG biocomposites exhibited excellent catalytic activity and remarkable reusability. The catalytic activity of the lipase-NPG biocomposite with a pore size of 35 nm had no decrease after ten recycles. Besides, the lipase-NPG biocomposite exhibited high catalytic activity in a broader pH range and higher temperature than that of free lipase. In addition, the leaching of lipase from NPG could be prevented by matching the protein’s diameter and pore size. Thus, the encapsulation of enzymes within NPG is quite useful for establishing new functions and will have wide applications for different chemical processes.     

Synthesis of osmium borides by mechanochemical method

Transition metal osmium borides were synthesized by mechanochemical method using high‐energy ball‐milling with Os (Osmium) and B (Boron) powders as raw materials. The formation process, reaction mechanism, and thermal stability of the mechochemically synthesized osmium borides were studied. Almost pure Os₂B₃ phase was obtained when the Os‐to‐B molar ratio was 1:2; while ReB₂‐type hexagonal OsB₂ with a small amount of RuB₂‐type orthorhombic OsB₂ was obtained when the Os‐to‐B molar ratio was 1:3. Stoichiometry OsB₂ was obtained from boron rich starting mixture powders due to the B loss during the high‐energy ball‐milling process. It was also found that WC and osmium oxide were present as contaminants after ball milling for 40 hours. Heat treatment results revealed that the as‐synthesized Os₂B₃ powders are thermally stable in flowing Ar up to 800°C, but a transformation from hexagonal to orthorhombic structure partially occurred for the OsB₂ powders as low as 600°C.     

聚氨酯增韧环氧灌封材料的制备与表征

以异氰酸酯封端的聚氨酯预聚体（PU）与环氧树脂（EP）发生反应,制备了聚氨酯接枝改性环氧灌封材料。FTIR表明异氰酸酯封端的聚氨酯预聚体与环氧树脂中的仲羟基完全反应,同时考察了活性稀释剂用量对树脂黏度的影响及固化过程中温度的变化。聚氨酯预聚体的加入,使材料的冲击强度和弯曲强度都有所升高,当聚氨酯质量分数为5％时,材料的弯曲强度提高了30%,而冲击强度提高了近200%,玻璃化转变温度没有降低,SEM分析了其增韧机理。     

Oxidative ammonolysis of peat by a mechanochemical method (Short communication)

The effects of the duration of a mechanochemical synthesis and the amounts of hydrogen peroxide and ammonia on the concentrations of nitrogen, humic acids, and fulvic acids in the oxidative ammonolysis products of peat were studied. The functional-type composition of nitrogen compounds was studied. Agrochemical tests of the resulting preparations as nitrogen-containing fertilizers were performed.     

溶胶-凝胶法制备碳化硅研究进展

碳化硅陶瓷材料因其优良的物理、化学性质而备受关注,作为先进材料可广泛用于石油化工、机械工业、宇航和汽车工业.相比较传统的制备方法,溶胶-凝胶法具有合成温度低、纯度高和均匀性好等优点.在简述溶胶-凝胶法基本原理的基础上,较系统地评述了溶胶-凝胶法制备碳化硅纳米微粉、碳化硅一维纳米材料、碳化硅纳米复合陶瓷和多孔碳化硅陶瓷材料及其他碳化硅材料的研究现状,提出了今后溶胶-凝胶法制备碳化硅材料的主要研究方向.     

机械力化学法制备超细钛酸镁粉体

以碱式碳酸镁、二氧化钛为原料,采用机械力化学法合成超细钛酸镁粉体.采用X射线衍射仪、扫描电镜、激光粒度分析仪、差热分析仪等对材料在制备过程中的晶粒形貌、固态相变和热稳定性进行了分析.结果表明:随着球磨过程的进行,物料很快细化,球磨30 h后,粉体粒径在2～5 μm.高能球磨破坏了粉体的晶体结构,随着球磨时间的增加,混合物粉体的比表面积增加,球磨时间达到30 h时,粉体呈现无定形状态,粉体经热处理结晶生成钛酸镁,结晶温度大大降低,由1 000℃降到700℃.     

Optical properties of ZnS nanoparticles produced by mechanochemical method

Nanosized zinc sulfide (ZnS) has been synthesized by the mechanochemical route using zinc acetate and sodium sulfide as source materials in a high energy planetary ball mill (HEPBM) with 300 rpm for 2 h. The mechanochemically synthesized powders have been analyzed by X-ray diffraction (XRD) for phase analysis, Field Emission Scanning Electron Microscope (FESEM) for the morphological characterization, UV–vis–NIR spectrophotometer for determining band gap energy and Fluorescence spectroscopy for determining the emission wavelength. The crystallite size of the synthesized ZnS nanoparticles calculated by the Debye–Scherer's formula is in the range 7–9 nm. FESEM morphology shows the fibrous structure of ZnS samples. The value of optical band gap has been found to be in the range 5.2–5.3 eV. Room temperature photoluminescence (PL) spectrum of the samples exhibits a blue light emission using UV excitation wavelength of 280 nm.     

A novel method of preparation of silicon-on-diamond materials

A new method of preparation of silicon-on-diamond materials is discussed in detail. Pre-characterization of the samples surfaces has been carried out, in order to calculate the optimal pressure for surface contact before the bonding process. The method is based on pulsed laser irradiation, in the 20 ps–7 ns range, at a wavelength of 355 nm, for which diamond is transparent and silicon highly absorbing. Under these conditions the material melts locally, within 100 nm at the interface, giving rise to amorphous silicon and silicon carbide. The mechanical strength of the bonding has been assessed by adhesion tests. Preliminary result on resistance to thermal annealing at 400 C in air is also reported. Uniformity of the silicon–diamond interface has been verified by scanning electron microscopy. Raman and infrared spectroscopy allowed to detect and estimate quantitatively the amorphous Si and SiC phases at the interface. A finite element simulation has been carried out, taking into account the processes occurring during the laser pulse and the subsequent cooling of the materials. As a result, energy densities per pulse required to melt locally diamond and silicon have been obtained as functions of the pulse width, giving a rationale to the formation of the SiC bond in terms of diamond–silicon inter diffusion. The experimental results of bondings performed at various energy density and pulse widths are in agreement with the model. The experimental results and the theoretical predictions are compared and discussed.     

Hydrogen evolution performance of magnesium alanate prepared by a mechanochemical metathesis reaction method

Solvent-free magnesium alanates were prepared by a mechanochemical metathesis reaction method (ball milling method) with a variation of milling time. For the purpose of comparison, magnesium alanate was also prepared by metathesis reaction method in the presence of diethyl ether. The formation of magnesium alanate (Mg(AlH₄)₂) and magnesium alanate-diethyl ether (Mg(AlH₄)₂·Et₂O) adduct was confirmed by XRD measurements. In both magnesium alanates, hydrogen evolution occurred in the first step decomposition. The starting temperature for hydrogen evolution of the solvent-free magnesium alanates decreased with increasing milling time, whereas the amount of hydrogen evolution of the solvent-free magnesium alanates increased with increasing milling time. The maximum amount of hydrogen evolution of the Mg(AlH₄)₂·Et₂O adduct was slightly larger than that of the solvent-free Mg(AlH₄)₂, but the starting temperature for hydrogen evolution of the Mg(AlH₄)₂·Et₂O adduct was much higher than that of the solvent-free Mg(AlH₄)₂. The addition of a small amount of titanium to the solvent-free Mg(AlH₄)₂ greatly reduced the hydrogen evolution temperature of titanium-doped Mg(AlH₄)₂. However, the maximum amount of hydrogen evolution of the titanium-doped Mg(AlH₄)₂ was smaller than that of the solvent-free Mg(AlH₄)₂.     

Efficient preparation of carbon fibers using plasma assisted stabilization

Carbon fibers (CFs) were prepared by the plasma-assisted stabilization (PAS) of polyacronitrile (PAN) fibers. PAS was found to be an efficient treatment for stabilizing the precursor fibers in terms of the time, cost and mechanical properties compared to conventional thermal stabilization (CTS). The efficient stabilization of PAN by a radio-frequency capacitive plasma discharge was confirmed using FT-IR and DSC. The tensile strength and modulus of CFs from PAS were superior to those of CFs from CTS. These results suggest that PAS is an efficient treatment for the manufacture of CFs, which can save time and energy.     

机械化学法降解氯代有机污染物的研究进展

机械化学法作为一种非焚烧处理技术,具有反应条件温和、操作简单、高效清洁和适用范围广等特点,近年来受到广泛关注,尤其是在对氯代有机污染物的削减中表现出显著的优势。本文综述了机械化学法在降解氯代有机污染物领域的研究进展,介绍了机械化学法的发展及其特性,归纳总结了常用于球磨体系中的单一添加剂和组合添加剂的种类,探究了球磨装置及运行参数对氯代有机污染物降解的影响;重点阐述了添加剂的作用方式和几种典型的氯代有机污染物的机械化学降解路径,其中包括六氯苯、多氯联苯、五氯酚、滴滴涕、得克隆和多氯萘。最后,针对当前机械化学法降解氯代有机污染物的研究现状,简述了有待解决的问题并展望了未来的发展方向,以期推进机械化学法降解理论的深入研究和技术的广泛应用。     

Enhancing ACE-inhibition of food protein hydrolysates by selective adsorption using porous carbon materials

Bioactive peptides from food proteins such as natural ACE (angiotensin-converting enzyme)-inhibitors have attracted particular attention for their potential to prevent hypertension. ACE-inhibiting peptides were enriched from food protein hydrolysates prepared from α-lactalbumin and lysozyme by selective adsorption on microporous activated carbons. For the eluate, it was shown by liquid chromatography that the strongest inhibitor isoleucyl-tryptophan was enriched by a factor of 11.2 compared to the initial α-lactalbumin hydrolysate. Natural inhibitors derived from lysozyme hydrolysates (e.g., alanyl-tryptophan) were successfully enriched as well. Identification of the enriched peptide fraction by mass spectroscopy revealed the hydrophobic character of the enriched peptides. The molecular weight distribution of the enriched peptide fraction can be controlled by the pore size distribution of the chosen adsorbent, which was proven by size exclusion chromatography of enriched peptide fractions derived from three different model carbons differing in their pore size. The selective enrichment of natural ACE-inhibitors from the α-lactalbumin hydrolysate lead to a 6 times stronger in vitro ACE-inhibition demonstrating the high potential as ingredients for hypotensive functional foods with reduced side effects.     

Preparation of liposomes modified with lipopeptides using a supercritical carbon dioxide reverse-phase evaporation method

Although liposomes are considered to be one of the most promising carriers for drug delivery systems (DDS), they have drawbacks such as insufficient drug-entrapment efficiency and long-term stability. The objectives of this study are to improve the trapping efficiency by addition of lipopeptides (LPs), and using a supercritical CO(2) reverse-phase evaporation (SCRPE) process, along with incorporation of PEG-modified phospholipids to improve long-term stability. In this study, bovine serum albumin (BSA) was used as a model drug substance for entrapment by liposomes. Improvements in the entrapment efficiency and stability of liposomes were achieved by modification with LPs and use of a SCRPE preparation process. The BSA-entrapment efficiency of liposomes modified with cationic LPs with arginine residues, as a result of their ionic interactions, was six times that of liposomes prepared by the Bangham method. Use of a SCRPE method along with LP modification further enhanced entrapment and enabled spontaneous formation of unilamellar liposomes with long-term stability. Liposomes consisting of DPPC/Chol/C(16)-Arg2/DSPE-PEG2000 (60/30/5/5), with up to 70% entrapment efficiency for BSA and a stability level of 90% for over 40 h, were obtained. DSC and SAXS analyses indicated that certain amounts of LP in the DPPC induced phase-transitional and structural changes in the lamellar membrane, and these changes improved the DDS carrier properties.The SCRPE method provides organic-solvent-free liposomes, and the LPs for the liposome modification are derivatives of amino acids and fatty acids, which are sustainable and biocompatible materials. This study therefore suggests that there are opportunities for the development of novel DDS carriers with excellent performance and which address environmental concerns.     

ATRP法制备环境响应型智能膜材料的研究进展

聚（N-异丙基丙烯酰胺）（PNIPAM）作为一种常见的智能材料,同时具有温度响应特性和乙醇浓度响应特性。本文以PNIPAM聚合物为主线,着重介绍了利用原子转移自由基聚合（ATRP）法制备温度响应型、温度及pH值双重响应型、乙醇浓度响应型智能膜材料的研究成果。其中,温度响应型智能膜主要介绍PNIPAM均聚物接枝膜;温度及pH值双重响应型智能膜主要介绍PNIPAM与pH值响应型聚合物的嵌段接枝膜;乙醇浓度响应型智能膜主要介绍PNIPAM无规共聚物接枝膜。另外,还介绍了其它响应型智能膜,包括手性分子及离子响应型接枝膜的研究成果。基于ATRP法在文中所述的优点以及在膜改性研究方面的广泛应用,相信该方法在制备环境响应型智能膜材料以及推动智能膜实际工业应用方面将扮演重要角色。     

Simple method for preparation of thermally expandable microspheres of PMMA encapsulating NaHCO3 via thermally induced phase separation

Thermally expandable microspheres (TEMs) employing poly(methyl methacrylate) (PMMA) as shell and sodium bicarbonate (NaHCO₃) as core were prepared by a simple method of thermally induced phase separation (TIPS). The addition of NaHCO₃ improved the foaming properties of TEMs. The effects of preparation parameters on the morphology, amount of encapsulated NaHCO₃, and foaming properties of TEMs were studied; the parameters investigated included the quench rate, the molecular weight (M_w) and amount of PMMA, and the amount of NaHCO₃. The results show that when 0.5 g of PMMA 50k, 3 g of NaHCO₃, and 50 g of ethanol were used, with quenching temperature at 0 °C, the TEMs were fully spherical and the maximum expansion volume of TEMs was about 3.8 times the original volume. The expansion volume of TEMs increased with increasing amount of encapsulated NaHCO₃, and the foaming onset temperature and temperature of complete bursting of TEMs were related to the M_w of PMMA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46179.     

Efficient and selective extraction of magnolol from Magnolia officinalis by mechanochemical extraction technique

Mechanochemical extraction technique was explored for efficient and selective extraction of magnolol from Magnolia officinalis. This process was carried out using a high intensive activator, AGO-2. The yield of magnolol via mechanochemical method was maximized under the following conditions: milling with Na₂CO₃ (2.0 wt%) for 7 min; extraction by water at 40 °C and liquid/solid ratio of 25:1 mL/g for 20 min; precipitation at pH 3.5. The results from scanning electron micrographs, infra-red spectrum and nuclear magnetic resonance indicate that mechanochemical action could result in the disruption of cell walls and the transformation of magnolol into a water-soluble salt form with the addition of sodium carbonate. Compared with superfine grinding extraction and heat-reflux extraction, mechanochemical extraction method reduced both extraction time and temperature, and also achieved a higher magnolol yield and content in the crude extracts.     

超临界流体技术制备超微材料应用

汇总了近年来国内外文献中关于超临界流体技术制备超微材料的应用,主要应用在高分子与生物材料、无机和有机材料、药物化合物、炸药等领域,提供了所制备超微材料的名称、应用的制备方法、主要实验结果和出处;介绍了超临界流体技术在制备合成微粒和颗粒包覆过程的应用,并对此应用技术目前存在的问题和发展前景进行了总结和展望。     

离子膜电解法制重铬酸钠阳极材料性能比较

为从源头解决铬盐生产中环境污染的问题,亟需探索清洁高效的重铬酸钠生产技术。将具备高效、清洁特点的离子膜电解技术引入到重铬酸钠合成中,利用离子膜电解法制取重铬酸钠可以减轻铬盐生产中的污染问题,是一种清洁、高效的生产技术。针对离子膜电解工艺中关键设备阳极板材进行了实验研究,考察了其槽电压、电流效率、直流电耗的变化。并且通过其性能和经济效益的综合比较,发现氧化铱钛板的各方面参数均符合电解生产工艺要求,而且造价较低廉,是性价比较高的阳极板备选材料。