HPMC凝胶模板诱导羟基磷灰石的合成

以羟丙基甲基纤维素（hydroxypmpylmethyl cellulose,HPMC）水凝胶作为模板合成了羟基磷灰石．利用X射线粉末衍射（XRD）、扫描电子显微镜（SEM）和傅里叶变换红外光谱（FTIR）等检测手段对所得的产物进行了形貌与结构表征．结果表明：HPMC水凝胶模板可以诱导羟基磷灰石的形成;模板分子上的多羟基与磷灰石晶体有一定的相互作用,模板的疏水微区和凝胶网络结构为磷灰石的形成提供了微环境,也决定着磷灰石晶体的微观形貌．     

丹皮酚亲水凝胶骨架片的制备及体外释放

以羟丙甲基纤维素(HPMC)为主要载体制备了丹皮酚(PN)的缓释骨架片。在载体中添加不同的释放调节剂,比较了对药物释放的影响;考察了不同黏度的HPMC及其用量对释放的影响;通过对体外释放数据进行零级方程、Higuchi和Peppas方程拟合,探讨了药物的释放机制。结果表明,以微晶纤维素为释放调节剂所制备的骨架片呈现良好的缓释特征,2 h释放31%,6 h释放66%,12 h释放99%。药物释放数据可以用Peppas方程(Q=Ktn)进行很好拟合,并且有0.45n0.89(n=0.6685),提示药物的释放机制为非Fichian扩散,即药物是通过凝胶层扩散和骨架溶蚀控制的释放。     

高强度物理-化学混杂双网络水凝胶的制备及性质

以聚乙烯醇（polyvinyl alcohol, PVA）和丙烯酰胺（acrylamide, AM）为原料, 采用“一锅煮”及紫外辐照结合冷冻 解冻两步聚合法制备聚乙烯醇/聚丙烯酰胺(PVA/PAM)混杂双网络水凝胶, 并对水凝胶的力学性能、 溶胀性能、 失水性能以及自愈合性进行测试和分析. 结果表明, PVA/PAM混杂双网络水凝胶具有较高的力学强度, 其拉伸强度为428 kPa, 失水速率和单网络水凝胶相比较慢, 具有一定的自愈合性.     

Reaction of CH radical with O<Subscript>2</Subscript> by time-resolved FTIR spectroscopy

The Methylidyne radical, CH, plays a crucial role in several complex environments such as planetary atmos- pheres and interstellar clouds, and is one of the most im- portant and active intermediate in hydrocarbon flames[1]. The CH involving reactions, including chemiionization, oxidation of hydrocarbons, the soot formation[2—5], and especially the formation of prompt NO[6], are of funda- mental interest in combustion chemistry, owing to the high reactivity and the large enthalpy of formatio…     

羧甲基壳聚糖接枝聚丙烯酸水凝胶的制备及体内外评价

以丙烯酸(AA)和羧甲基壳聚糖(CMC)为单体,通过热引发自由基接枝共聚反应,制备了一种新型pH敏感的羧甲基壳聚糖接枝聚丙烯酸(CMC-g-PAA)水凝胶。FT-IR结果表明成功实现了聚合反应,溶胀性实验表明CMC-g-PAA水凝胶具有明显的pH敏感性。以胰岛素(INS)为模型药物,将其负载到CMC-g-PAA水凝胶中,得到了载药量为216.5mg/g的载药凝胶。体外释放曲线表明:在pH值为1.2的条件下,2h后INS的累计释放量为(16.3±2.6)%;在pH值为7.4的环境中,2h后INS的累计释放量达到(57.2±3.5)%。说明载药凝胶可以在肠道环境中靶向释放INS,避免INS被胃酸和胃蛋白酶破坏。动物实验结果表明,负载INS水凝胶具有良好的降血糖效果。CMC-g-PAA水凝胶与Caco-2细胞共同培养,细胞存活率接近100%,表明水凝胶对Caco-2细胞没有细胞毒性。CMC-g-PAA水凝胶在蛋白或多肽类药物定位递送方面具有优良的应用前景。     

Mineral-phase evolution and sintering behavior of MO-SiO2-Al2O3-B2O3 (M=Ca,Ba) glass-ceramics by low-temperature liquid-phase sintering

In this work, network former SiO₂ and network intermediate Al₂O₃ were introduced into typical low-melting binary compositions CaO·B₂O₃, CaO·2B₂O₃, and BaO·B₂O₃ via an aqueous solid-state suspension milling route. Accordingly, multiple-phase aluminosilicate glass-ceramics were directly obtained via liquid-phase sintering at temperatures below 950℃. On the basis of liquid-phase sintering theory, mineral-phase evolutions and glass-phase formations were systematically investigated in a wide MO-SiO₂-Al₂O₃-B₂O₃ (M=Ca, Ba) composition range. The results indicate that major mineral phases of the aluminosilicate glass-ceramics are Al₂₀B₄O₃₆, CaAl₂Si₂O₈, and BaAl₂Si₂O₈ and that the glass-ceramic materials are characterized by dense microstructures and excellent dielectric properties.     

Synthesis and Structure of Polypyrrole Derivatives／V2O5 Nanocomposites

Poly ( N, N, N-trimethyl ( 2-pyrrol-l-yl ) ethyl ammonium iodide )/V2O5 ( PTPAI/V2O5) nanocomposites were synthesized by sol-gel method. This method involved formation of vanadium pentoxide xerogel in the prcscnce of polypyrrole derivatives solution. X-ray diffraction(XRD) indicated that the polypyrrole derivative particles encapsulated in the fibrous V2O5 network and the layered distance significantly increased from 1. 077 39 to 1. 354 56 nm. The interaction between polypyrrole and V2O5 in the ‘nanocomposites‘ was characterized by IR spectroscopy. The Scanning Electron Microscope(SEM) micrographs reveal the structural contrasts between the hybrid materials and the pristine vanadium oxide xerogel.     

亲水/疏水半互穿网水凝胶对丙酮/水溶液的响应

考察了亲水／疏水半互穿网凝胶在不同体积分数的丙酮／水溶液中的溶胀或消溶胀情况。随着聚丙烯酸（PAAc）网络内疏水改性聚电解质高分子鲢N－正十二烷基聚（4－乙烯吡啶）溴化盐（QPVPD）含量的增加,半互穿网水凝胶内部的物理缠绕和疏水相互作用增强,致使含QPVPD较多的样胶在丙酮体积分数为50％附近溶胀率较大。随着丙酮体积分数继续增大,所有样品胶迅速收缩。该凝胶的溶胀是动力学平衡过程,在丙酮／水溶液中,其溶胀率需1周才达到最大值。随着网络的QPVPD含量的增加,凝胶的消溶胀速率和程度降低。     

Reinforcing effect of graphene on the mechanical properties of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/TiC ceramics

Multilayer graphene (MLG)-reinforced Al₂O₃/TiC ceramics were fabricated through hot pressing sintering, and the reinforcing effect of MLG on the microstructure and mechanical properties of the composites was investigated by experiment and simulation. The simulation of dynamic crack initiation and propagation was investigated based on the cohesive zone method. The results show that the composite added with 0.2wt% MLG has excellent flexural strength and high fracture toughness. The major reinforcing mechanisms are the synergistic effect by strong and weak bonding interfaces, MLG pull-out, and grain refinement resulting from the addition of MLG. In addition, the aggravating of crack deflection, branching, blunting, and bridging have indispensable contribution to the improvement of the as-designed materials.     

Preparation and radar-absorbing properties of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/TiO<Subscript>2</Subscript>/Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/Yb<Subscript>2</Subscript>O<Subscript>3</Subscript> composite powder

Al₂O₃/TiO₂/Fe₂O₃/Yb₂O₃ composite powder was synthesized via the sol-gel method. The structure, morphology, and radar-absorption properties of the composite powder were characterized by transmission electron microscopy, X-ray diffraction analysis and RF impedance analysis. The results show that two types of particles exist in the composite powder. One is irregular flakes (100-200 nm) and the other is spherical Al₂O₃ particles (smaller than 80 nm). Electromagnetic wave attenuation is mostly achieved by dielectric loss. The maximum value of the dissipation factor reaches 0.76 (at 15.68 GHz) in the frequency range of 2-18 GHz. The electromagnetic absorption of waves covers 2-18 GHz with the matching thicknesses of 1.5-4.5 mm. The absorption peak shifts to the lower-frequency area with increasing matching thickness. The effective absorption band covers the frequency range of 2.16-9.76 GHz, and the maximum absorption peak reaches -20.18 dB with a matching thickness of 3.5 mm at a frequency of 3.52 GHz.     

石墨烯基聚苯胺水凝胶的电化学性能研究

通过两步溶液自组装方法,制备了具有三维多孔网络结构的石墨烯基聚苯胺复合水凝胶(PR-x),并通过SEM、XRD、FT-IR、Raman、XPS等表征手段对样品的微观形貌和结构组成进行了表征分析.结果表明,聚苯胺均匀地负载于三维多孔石墨烯网络骨架,且能够显著抑制石墨烯的团聚现象.研究了石墨烯基聚苯胺复合水凝胶电极的电化学性能.当聚苯胺质量分数为75％,电流密度为1 A·g-1时,比电容为762.8 F·g-1;当扫描速率从5 mV·s-1增加到50 mV·s-1时,倍率保留率高达77％,经过3000次恒电流充放电后比电容保留率仍高达89.27％.该石墨烯基聚苯胺复合水凝胶电极作为超级电容器表现出优异的放电容量、倍率性能和循环稳定性,具有一定的潜在应用价值.     

Electro-deoxidation of V<Subscript>2</Subscript>O<Subscript>3</Subscript> in molten CaCl<Subscript>2</Subscript>-NaCl-CaO

The electro-deoxidation of V₂O₃ precursors was studied. Experiments were carried out with a two-terminal electrochemical cell, which was comprised of a molten electrolyte of CaCl₂ and NaCl with additions of CaO, a cathode of compact V₂O₃, and a graphite anode under the potential of 3.0 V at 1173 K. The phase constitution and composition as well as the morphology of the samples were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). 3 g of V₂O₃ could be converted to vanadium metal powder within the processing time of 8 h. The kinetic pathway was investigated by analyzing the product phase in samples prepared at different reduction stages. CaO added in the reduction path of V₂O₃ formed the intermediate product CaV₂O₄.     

Work toughening effect in Zr_（41）Ti_（14）Cu_（12.5）Ni_（10）Be_（22.5） bulk metallic glass

Work hardening is a well-known phenomenon occurring in crystalline metals during deformation,which has been widely used to increase the strength of metals although their ductility is usually reduced simultaneously. Here we report that the plastic strain of Zr41Ti14Cu12.5Ni10Be22.5 (at.%) bulk metallic glasses has been increased from 0.3% for the as-cast sample to 2.5%-8.0% for samples that have experienced pre-deformation under constrained conditions. The pre-deformed glassy alloys possess more free volume and abundant introduced shear bands,which are believed to promote the activation of shear bands in post-deformation and result in an increase in plasticity. The orientation of the pre-introduced shear bands relative to the loading direction will affect the deformation behavior of pre-deformed samples. The present results show that pre-deformation of this glassy alloy will result in work toughening. This work toughening effect can be removed by isothermal annealing at a sub-Tg (glass transition) temperature,which causes annihilation of free volume and healing of shear bands.     

Synthesis and characterization of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@SiO<Subscript>2</Subscript> magnetic composite nanoparticles by a one-pot process

Fe₃O₄@SiO₂ core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe₃O₄@SiO₂ core–shell structures from prepared Fe₃O₄ nanoparticles. The properties of the Fe₃O₄ and Fe₃O₄@SiO₂ composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe₃O₄ particles were approximately 12 nm in size, and the thickness of the SiO₂ coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe₃O₄@SiO₂ powder (34.85 A·m2·kg–1) was markedly lower than that of the Fe₃O₄ powder (79.55 A·m2·kg–1), which demonstrates that Fe₃O₄ was successfully wrapped by SiO₂. The Fe₃O₄@SiO₂ composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.     

蛋白质水凝胶中可冻结水的同步热分析结果及其讨论

蛋白质水凝胶中水状态的研究有利于深入了解蛋白质水凝胶的结构、性能与功能.本文选用鸡蛋蛋清作为蛋白质水凝胶样品,利用同步热分析仪,在10K/min的升温过程中,分别研究密封坩埚内蛋清和蒸馏水的热流Φ、相对质量m/m0随温度T的变化情况.经过研究分析得到了如下结果：1）蛋清和蒸馏水在-50℃～50℃温度范围内的升温过程中都出现了熔化现象,而且实验结果具有很好的重复性,蛋清发生的变化为可逆变化,并且与热历史无关.2）蛋清和蒸馏水的熔化峰的峰形在高温区表现了很好的相似性,在低温区（-15～0℃）明显不同,表明蛋清和蒸馏水在熔化初始时,各自所对应的熔化行为并不相同,但是在峰值温度以上温区内,二者的熔化行为是相同的.3）凝胶网状结构影响蛋清中可冻结水晶粒尺寸的分布,该分布不同于蒸馏水中晶粒分布,使得蛋清的熔化峰出现的温度低于蒸馏水的熔化峰温,并且熔化初始时的行为与蒸馏水不同.4）利用DSC方法通过熔化峰的吸热量计算蛋白质水凝胶中可冻结水含量的方法存在系统误差,但偶然误差小.     

Shear-thinning behavior of the CaO-SiO2-CaF2-Si3N4 system mold flux and its practical application

Satisfying the mold-flux performance requirements for high-speed continuous casting necessitates the development of a new non-Newtonian-fluid mold flux with shear-thinning behavior, i.e., a mold flux whose viscosity is relatively high under lower shear rates and relatively low under higher shear rates. In this work, a mold flux that exhibits shear-thinning behavior was developed by adding different amounts of Si₃N₄ to the CaO-SiO₂-CaF₂ mold flux. The shear-thinning behavior was investigated using a rotational viscometer. In addition, the microstructure of the newly prepared slags was studied by high-temperature Raman spectroscopy and X-ray photoelectron spectroscopy. The results showed that the mechanism of shear-thinning was attributable to a temporary viscosity loss caused by the one-way shear stress, whereas the corresponding magnitude of shear-thinning was closely related to the degree of polymerization (DP). Finally, the non-Newtonian fluid mold flux was used for laboratory casting tests, which revealed that the mold flux could reduce slag entrapment and positively affect the continuous casting optimization.     

Synthesis, Characterization and Calorimetry of Ni（C4H8N2O3）2Cl2

A coordination complex was synthesized from NiCl2 and dipeptide glycylglycine（GG）. It was characterized by element analysis, NMR and TG methods, and then was determined to be Ni（C4HsN2O3）2Cl2. Using an isoperibolic reaction calorimeter, the standard molar enthalpy of formation of Ni（GG）2Cl2（solid） has been determined to be -（1 674.66±2.02） kJ · mol^-1 at 298.15 K.     

Analysis of the factors affecting the magnetic characteristics of nano-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> particles

We prepared Fe3O4 nanoparticles using chemical coprecipitation and studied the factors affecting the magnetic characteristics of nano-Fe3O4 particles.We identified four factors and three levels of an orthogonal experiment and investigated these four factors that affect the magnetic characteristics of the Fe3O4 particles.We obtained important information from this investigation.The Fe3+ to Fe2+ molar ratio,the iron precursor salt,the amount of surfactant and the amount of alkali were found to be important.We also studied the influence of the order of alkali and surfactant addition,the aging time and the stirring speed on the magnetic characteristics of the nano-Fe3O4 particles.The Fe3O4 preparation process was also analyzed.     

One-pot synthesis of PVP-coated Ni<Subscript>0.6</Subscript>Fe<Subscript>2.4</Subscript>O<Subscript>4</Subscript> nanocrystals

Novel poly(N-vinyl-2-pyrrolidone) (PVP)-coated nickel ferrite nanocrystals were prepared by simultaneously pyrolyzing nickel(II) acetylacetonate (Ni(acac)₂) and iron(III) acetylacetonate (Fe(acac)₃) in N-vinyl-2-pyrrolidone (NVP). The PVP coating was formed in situ through polymerization of NVP. The crystalline structure of the resultant nickel ferrite was analyzed by high-resolution transmission electron microscopy, electron diffraction patterns, and powder X-ray diffraction. In addition, the valence state of Ni and the metal contents of Ni and Fe in different valence states were analyzed by X-ray photoelectron spectroscopy (XPS), atomic absorption and the phenanthroline method. The surface coating layer of PVP and its binding states were characterized by Fourier transform infrared spectroscopy in combination with XPS. Colloidal stability experiments revealed that the nanocrystals could be dispersed well in both phosphate-buffered saline and Dulbecco’s Modified Eagle Medium.     

HPMC对水泥稳定全深式冷再生材料的性能影响研究

针对水泥稳定全深式冷再生混合料的泌水、施工操作时间短、黏结力不足等诸多问题,通过在水泥胶砂试件中添加羟丙基甲基纤维素醚(HPMC),研究HPMC对水泥胶砂试件抗折及抗压强度的影响;进而探讨在再生混合料中掺入HPMC的可行性,重点研究了不同掺量的HPMC对水泥稳定全深式冷再生材料的性能影响。研究发现:HPMC由于引气作用会降低水泥水化后水泥胶砂试件的抗折及抗压强度;水泥在HPMC溶于水后的分散液中进行水化,与水泥先水化再掺入HPMC相比,水泥胶砂试件抗折及抗压强度有所增大。掺入HPMC,对水泥稳定全深式冷再生材料的无侧限抗压强度有削弱作用;再生混合料具有一定黏聚性能不易离析,且在常温及高温下保水性能较好,基本无泌水现象。