Acrylic‐Based Polyurethane/Silica Hybrids Prepared by Acid‐Catalyzed Sol–Gel Process: Structure and Mechanical Properties

Summary: Silica sols were first prepared based on different ratios of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) by an acid‐catalyzed sol–gel process, and then incorporated into acrylic‐based polyurethanes. The structures and morphologies of silicone‐oxo clusters were studied by ²⁹Si NMR, SAXS, and scanning electron microscopy (SEM), whereas the mechanical properties of polyurethane/silica hybrids were characterized by DMA and tensile tests. The silicone‐oxo clusters in both silica sol and polyurethane hybrids became denser and larger at a higher molar ratio of TEOS/MTES and higher silica content, and the silica‐oxo clusters of polyurethane/silica hybrids even became more compact and larger than those of silica sols, increasing the elastic modulus and tensile strength of polyurethane/silica hybrids.

Typical structure of silica sol prepared from the hydrolysis and condensation of TEOS and MTES with acid as the catalyst.     

Hydrogen Production by Steam Reforming of Ethanol over Nickel Catalysts Supported on Sol Gel Made Alumina: Influence of Calcination Temperature on Supports

Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/Al_S.G.) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/Al_S.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/Al_S.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size.     

天然高分子白及溶胶的制备及质量控制

目的制备高分子白及溶胶,制定质量控制方法。方法用水提醇沉法提取,0.1%活性炭脱色,所得多糖干燥、粉碎、加纯化水制备成溶胶;从性状、鉴别、含量测定方面控制质量。结果所制得白及溶胶为浅棕色半流动状,质地均匀,细腻,具有粘性,鉴别呈正反应,溶胶中含白及多糖为4.0%(±5),含量测定多糖在1.88~33.75μg.m L-1范围内线性关系良好,y=0.034X-0.0069(r=0.9998),回收率为98.6%,RSD=1.12%(n=9)。结论该方法制备的白及溶胶均匀、细腻,质量可控。     

Tuning of Sol–Gel Transition in the Mixed Polymer Micelle Solutions of Copolymer Mixtures Consisting of Enantiomeric Diblock and Triblock Copolymers of Polylactide and Poly(ethylene glycol)

Poly(ethylene glycol) (PEG) is partially furanylated with different feed ratios of furfuryl isocyanate and used as the macro initiator of ring‐opening polymerization of l ‐ and d ‐lactides to synthesize copolymer mixtures of furan‐terminated AB diblock and ABA triblock copolymers (poly(oxyethylene)–poly(l ‐lactide)/poly(l ‐lactide)–poly(oxyethylene)–poly(l ‐lactide) and poly(oxyethylene–poly(d ‐lactide)/poly(d ‐lactide)–poly(oxyethylene)–poly‐(d ‐lactide)) having different diblock/triblock ratios. The mixed micelle solutions of these enantiomeric copolymer mixtures undergo sol‐to‐gel or gel‐to‐sol transition depending on the diblock/triblock ratio of the copolymer mixtures. The rheological properties of the mixed micelle solutions could also be controlled by changing the diblock/triblock ratios or the initial furanylation ratio of PEG.

     

Photo‐Cured Epoxy Networks Functionalized With Fe3O4 Generated by Non‐hydrolytic Sol–Gel Process

Magnetite nanoparticles were prepared by a non‐hydrolytic sol–gel (NHSG) process in the presence of benzyl alcohol. The obtained magnetite suspensions were mixed with an aliphatic epoxy resin and the formulations were photo‐polymerized to achieve composite materials with magnetic properties. The prepared magnetite nanoparticles and epoxy composites were fully characterized in terms of their magnetic properties.     

Feasibility of a closed‐system cell processor (ACP215) for automated preparation of washed platelet concentrates

Background and Objectives This study was aimed at evaluating the feasibility of the ACP215 closed‐system cell processor for preparing washed platelet concentrates. Material and Methods Platelet washing was performed with either the ACP215 system or the manual technique with M‐sol. Plasma protein removal and platelet recovery were estimated, and the washed platelet concentrates were stored for 5 days. Samples were collected after washing and on days 1, 3 and 5 of storage to determine the effects of the washing methods on the in vitro platelet qualities (platelet count, platelet volume, pH, glucose and lactate concentrations, hypotonic shock response, aggregation response and CD62P expression level). Results Platelet recovery was 86·9 ± 2·1% and 85·9 ± 1·9% (P = 0·305), and plasma protein removal was 95·8 ± 0·9% and 96·9 ± 0·7% (P = 0·016) after washing with the ACP215 system and manual technique, respectively. No statistically significant differences in the in vitro platelet qualities were observed between the washing methods. Conclusion The ACP215 system is a feasible alternative to manual, labour‐intensive, techniques for preparing washed platelet concentrates.     

Experimental and Molecular Dynamics Simulation Study on Sol–Gel Conversion Process of Aluminum Carboxylate System

Due to the lack of relevant in situ characterization techniques, the investigation of aluminum sol–gel progress is lacking. In this study, combined with molecular dynamics simulation and conventional experimental methods, the microstructures, rheological properties, and gelation process of the carboxylic aluminum sol system were studied. The experimental results showed that, with the increase in solid content, the microstructure of the colloid developed from a loose and porous framework to a homogeneous and compact structure. The viscosity of aluminum sol decreased significantly with the increase in temperature, and a temperature above 318 k was more conducive to improving the fluidity. The simulation results show that the increase in free volume and the connectivity of pores in colloidal framework structure were the key factors to improve fluidity. In addition, free water molecules had a higher migration rate, which could assist the rotation and rearrangement of macromolecular chains and also played an essential role in improving fluidity. The Molecular dynamics simulation (MD) results were consistent with experimental results and broaden the scope of experimental research, providing necessary theoretical guidance for enhancing the spinning properties of aluminum sol.     

6～7岁儿童第一恒磨牙窝沟封闭防龋效果观察

目的:了解窝沟封闭剂预防龋齿的临床效果。方法:将4 6 7例儿童的第一恒磨牙分为两组,一侧第一恒磨牙进行光固化窝沟封闭,为实验组;另侧同名牙不做封闭,为对照组。进行1～3年的随访观察。结果:封闭了93 4颗牙,3年复查后的封闭剂保留率76. 0 5 % ,龋齿降低率92. 6 5 %。结论:窝沟封闭能有效地预防窝沟龋的发生,是目前预防窝沟龋的较好方法之一     

Study on the Influence of Nanosilica Sol on the Hydration Process of Different Kinds of Cement and Mortar Properties

Compared with nanosilica collected in a gaseous state, nanosilica sol has great economic value and application significance for improving the performance of concrete and mortar. In this study, the influence of nanosilica sol on the hydration process of different kinds of cement is studied by means of hydration heat analysis, X-ray diffraction analysis (XRD) and other methods, and the properties of mortar such as setting time, mechanical properties and porosity are also studied to characterize the influence of nanosilica sol on the macroscopic properties of mortar. The experimental results show that nanosilica sol can accelerate the hydration rate of two kinds of cement and promote the hydration reaction degree of cement, and this promotion effect increases with the increase in nanosilica sol content. At the same time, nanosilica sol can significantly shorten the setting time of the two kinds of cement, and it is more obvious with the increase in content. Excessive content of nanosilica sol will adversely affect the permeability resistance of mortar. It may be caused by the weak interval formed by nanosilica particle clusters in the mortar matrix, which can be supported by the mortar pore structure distribution test. At the same time, the influence of nanosilica sol on the hydration of the two kinds of cement is different, and the compressive strength of HBSAC cement mortar increases first and then decreases after adding nanosilica sol; However, the compressive strength of P·O 42.5 cement mortar increases gradually after adding nanometer silica sol. This shows that nanosilica sol does not effectively promote the hydration of β-C2S in high belite sulfoaluminate cement (HBSAC) mortar. Based on the above experimental results, it can be concluded that when the content of nanosilica sol is about 1%, it has the best promotion effect on the hydration of the two kinds of cement and the performance of mortar.