CaF2对硅酸三钙的制备及其生物活性的影响

采用固相反应制备不同CaF掺量的生物活性硅酸三钙(3CaO·SiO22,C3S),并研究CaF2对C3S的制备及生物活性的影响.化学滴定、TGA/DTA、XRD、SEM和FTIR的分析结果表明,在煅烧过程中,CaF2有效的促进CaCO3的分解,并能形成低共熔化合物,促进C3S的形成;存急冷过程中,CaF2抑制CS晶型转变和分解,CaF2有效提高固相反应制备C§的纯度;模拟体液(SBD浸泡实验结果表明掺与小掺CaF2的C3s表面分别在1 d和3 d内诱导形成诱导磷厌石,这表明掺CaF2可以提高C3S的生物活性.     

Effects on the Thermal Properties and Bioactivity of Substitution of CaO by M2O3 (M=La, Y, Al) in Wollastonite Glass

The effects on the thermal properties and bioactivity of the substitution of CaO by La₂O₃, Y₂O₃ and Al₂O₃ in a glass of composition CaO·SiO₂ were studied and compared. The trivalent metal oxides were all effective in raising the glass transformation and softening temperatures when they replaced CaO in the glass of composition CaO·SiO₂. The experimental results suggest that Al₂O₃ plays the role of a glass-former, while La₂O₃ and Y₂O₃ behave as glass-modifiers. The tendency to devitrify appears to be the lower, the farther the glass composition is from those of the crystalline phases, owing to the need for diffusion over longer distances, the greater the composition difference. The substitution with the trivalent metal oxides is detrimental to the bioactivity, which is preserved only in the event of very small degrees of substitution. The most negative role appears to be played by Al₂O₃. This revised version was published online in July 2006 with corrections to the Cover Date.     

Crystallization in the SiO2-Al2O3 System from Amorphous Powders

The crystallization of amorphous chemically homogeneous powders in the SiO₂.Al₂O₃ system has been studied by differential scanning calorimetry and X-ray diffraction. Up to 1300°C only one exotherm has been observed. Only mullite crystallizes for compositions ≤69 mol% Al₂O₃ and spinel for those ≤80%. The crystallizations into mullite and spinel are sharp and exothermic, with an enthalpy of 250–300 J/g. The chemical composition of the crystallized mullite regularly increases from 68 to 76 mol% Al₂O₃ with increasing bulk composition from 60 to 75 mol% Al₂O₃.     

一种新的硅基晶体BaH2SiO4的结构和性能（英文）

本文报道了采用水热法生长BaH2SiO4单晶的实验结果,它属三斜晶系,空间群为P1,晶包参数为:a=7.079,b=7.362,c=7.5824A,α=89.64°,β=88.785°,γ=88.23°.原子力显微镜(AFM)和P-E铁电回线测量显示该材料具有铁电性,沿(010)方向极化强度和娇顽力分别为0.882μC·cm-2 and 1.12kV·cm-1,研究显示铁电性来源于材料中的氢键.     

SiO2-PEG凝胶体系的热物理化学特征

用程序升温热重法分析了SiO2及SiO2-PEG干凝胶的热物理化学行为,结果表明：采用不同的环境气氛对SiO2-PEG干凝胶进行热处理,聚乙二醇（PEG）表现出不同的热稳定性,并由此影响干凝胶的织构性质;通过对氮气气氛中得到的DTG曲线进行处理,得到不同温度段的表现活化能,说明SiO2干凝胶脱羟反应表现出动力学控制,而SiO2-PEG干凝胶随着温度的升高则表现出动力学控制逐步向表面羟基的扩散控制转变．     

Optical and Structural Properties of Zn2SiO4:Mn2+ from SLS Waste Bottle Obtained by a Solid State Method

In this studies, 2 wt.% Mn-doped Zn₂SiO₄ were synthesized from SLS waste glass, ZnO and MnO using conventional solid-state method. Structural and optical properties were examined as functions of sintering temperature. Density and linear shrinkage of samples increased with increasing in sintering temperature. X-Ray Diffraction pattern revealed that sintering temperature play an important role in enhancing crystallization of Zn₂SiO₄. It was found that the phase formation changed from amorphous to ȕ- Zn₂SiO₄ and then to α-Zn₂SiO₄ with the unsintered to sinter at 600 °C and 700 °C respectively. The morphology under FESEM characterization shows that the samples become more uniform with rectangular shape like as the sintering temperature increased. From UV-Vis spectroscopy, the results obtained showed that the intensive absorption occurred in the UV region, in the range of 250-γλ0 nm. Prominent green emission colours of α-Zn₂SiO₄ were observed centred at 527 nm while the yellow emission centred at η8η nm resulted from ȕ-Zn₂SiO at an excitation of 260 nm. However, red emission centred at 600 nm was observed for glass samples. These emissions come from the Mn-dopant and correspond to the ⁴T₁ – ⁶A₁ transition.     

Tb掺杂SiO2-B2O3-NaF玻璃的制备及发光性质

使用正硅酸乙酯、硼酸和氟化钠为前驱体,0.10 mol•L-1TbCl3溶液为掺杂剂,通过溶胶-凝胶方法制备了Tb3＋掺杂的SiO2-B2O3-NaF玻璃,研究了Tb3＋在SiO2-B2O3-NaF体系中的发光性质,结果显示发光体能产生强的绿色发光(544 nm),归属于Tb3＋的5D4—7F5电子跃迁.Tb3＋含量不同时,除发光强度不同外,其发射光谱基本相同,并且在低掺杂Tb3＋样品和低退火温度样品中检测到了来自5D3跃迁产生的峰,其跃迁随Tb3＋掺杂浓度的增加和退火温度的升高而发生猝灭,这种现象归因于5D3－5D47F6—7F0和/或5D3—7F07F6—5D4跃迁中发生了交叉弛豫现象.Tb3＋在SiO2-B2O3-NaF玻璃中的激发光谱由一个宽峰和一系列窄峰组成,宽峰最大波长位于230 nm,对应于Tb3＋的4f 8—4f 75d 1跃迁,一系列窄峰位于300～380 nm处,归属于4f 8跃迁,所有发光材料的XRD和TEM测试显示材料是非晶态的.     

The Effect of Volume Reorganization of Amorphous Poly(ethylene Terephthaiate) on Thermal Properties

When poly(ethylene terephthalate) was quenched from above T_g and then heated, it exhibited a step increase in thickness in the glass transition region at every rate tested. When the polymer was cooled more slowly than it was heated, a higher T_g and a slightly larger step increase in thickness were observed as the cooling rate was reduced. These experimental results appear to be adequately interpreted on the basis of the normal structural changes that occur in a glass as its thermal history is varied. Two observations, however, were not easily included in this view. First, the polymer, on cooling from above T_g, exhibited an abnormally high expansion coefficient over much of the range of temperature in which it exists as a fluid. Second, the polymer exhibited a step increase in thickness when it was heated at the same rate at which it had previously been cooled.     

Effect of MMT,SiO2, CaCO3, and PTFE nanoparticles on the morphology and crystallization of poly(vinylidene fluoride)

The crystallization and melting behaviors of poly (vinylidene fluoride) (PVDF) with small amount of nanoparticles (1 wt %), such as montmorillonite (MMT), SiO₂, CaCO₃, or polytetrafluoroethylene (PTFE), directly prepared by melt‐mixing method were investigated by scanning electron microscopy (SEM), polarizing optical microscopy, Fourier transform infrared spectroscopy, wide angle X‐ray diffraction (WAXD), and differential scanning calorimetry (DSC). The nanoparticle structure and the interactions between PVDF molecule and nanoparticle surface predominated the crystallization behavior and morphology of the PVDF. Small amount addition of these four types of nanoparticles would not affect the original crystalline phase obtained in the neat PVDF sample (α phase), but accelerated the crystallization rate because of the nucleation effect. In these four blend systems, MMT or PTFE nanoparticles could be well applied for PVDF nanocomposite preparation because of stronger interactions between particle surface and PVDF molecules. The nucleation enhancement and the growth rate of the spherulites were decreased in the order SiO₂ > CaCO₃ > PTFE > MMT. The melting and recrystallization of PVDF was found in MMT addition sample, because of the special ways of ordering of the PVDF chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

EDTA滴定法测定萤石中氟化钙含量的方法改进

建立了EDTA滴定法测定矿石中氟化钙的方法。引入了钙乙酸为溶解试样的溶剂,溶解样品中的碳酸钙,同时,通过同离子效应减少氟化钙的溶解度。实验中探究了钙离子的浓度与氟化钙溶解度的关系,通过对比实验确定选择了含钙乙酸的最佳浓度(10g/L)。同时,对实验中的其他条件也进行了相应的探究与优化,确定最佳实验条件为:最小称样量为0.5g,洗涤沉淀用水量为50mL左右,第二次过滤时的洗涤次数为8～10次,滴定时加入氢氧化钾的量为20mL。方法的精密度(0.10%)和准确度(0.08%)皆能满足实验要求。     

Thermal behaviors of amorphous calcium carbonates prepared in aqueous and ethanol media

Two different samples of amorphous calcium carbonate (ACC) hydrates were prepared respectively by mixing aqueous solutions of CaCl₂ and Na₂CO₃-NaOH and by allowing the diffusion of (NH₄)₂CO₃ sublimate into ethanol solution of CaCl₂. Thermal behaviors of the synthetic ACCs were investigated comparatively by means of thermoanalytical techniques complimented by powder X-ray diffraction, FTIR spectrometry and microscopic observations. The anhydrous ACCs produced by the thermal dehydration of the respective samples were crystallized to calcite in different ways. The sample prepared in aqueous medium was crystallized at around 600 K in a single step. Crystallization in two separated steps at around 600 and 825 K was observed for the sample prepared in ethanol medium. Characteristics of the crystallization processes were discussed from thermodynamic and kinetic points of view.     

费托合成中Co/ZrO2/SiO2催化剂的失活行为

 采用等体积分步浸渍法制备了费托合成用Co/ZrO2/SiO2催化剂,并用XRD,TPR和N2-吸附等手段对催化剂进行了表征. 考察了催化剂在费托反应过程中的结构变化和失活行为. 结果表明,反应过程中硅酸钴物种的生成是催化剂失活的主要原因,且硅酸钴的生成与产物水的分压有关; 晶粒长大也可能是催化剂失活的原因之一.     

土家族药物天葵化石汤提取液抑制草酸钙结石形成的化学模拟

采用扫描电子显微镜(SEM)和X射线衍射法(XRD)研究了土家族药物天葵化石汤(Tiankui)的提取液对尿石晶体草酸钙(CaOxa)成核、生长的抑制作用及其对二水草酸钙(COD)的稳定作用. 当Tiankui浓度小于30 mg/mL时, 主要生成一水草酸钙(COM), 但可使COM晶体棱角圆钝. 随着Tiankui浓度增加至45和75 mg/mL, 可分别诱导95%和100%的COD晶体生成. Tiankui还可以稳定COD在水溶液中的存在, 没有Tiankui存在时, COD在48 h内全部转化为COM晶体, 而在12 mg/mL Tiankui存在下, COD仅有20%转化. 从Tiankui提取液的活性组分、与草酸钙不同晶相间的吸附差异、化学配位等角度讨论了其抑制CaOxa生长和诱导稳定COD的化学基础.     

Li2O-CaO-Gd2O3-SiO2:Eu,Bi体系的结构和发光性能之间的关系

用X射线粉末衍射法研究了Li₂O-CaO-Gd₂O₃-SiO₂:Eu,Bi发光体系的物相组成随Gd₂O₃含量的变化,探讨了不同硅酸盐物种和结构对Eu³⁺和Bi³⁺发光特性的影响。结果表明,无Gd₂O₃组分时发光体是β-CaSiO₄多晶体,当Gd₂O₃/SiO₂比超过2.5%时,Ca₂Gd₈(SiO₄)₆O₂和LiGd₉(SiO₄)₆O₂物相逐渐增加,当其成为主要物相时,EU³⁺发光呈数倍增强,这2种含钆物相的结构既利于EU³⁺的红光发射又利于敏化剂向激活剂传输能量,所形成的固熔体是优良的发光基质材料。     

Eu3+掺杂SiO2-Al2O3-B2O3玻璃制备及光谱性能研究

高温溶制了Eu^3＋掺杂SiO2-Al2O3-B2O3-MxOy（M=Li^＋,Na^＋,K^＋,Mg^2＋,Ca^2＋,Sr^2＋,RE^3＋）硼硅酸盐玻璃,测试了玻璃样品的发射光谱、激发光谱和透射光谱,研究了不同碱金属离子、碱土金属离子对该系统荧光性能的影响。利用发射光谱计算了Ω2,Ω4以及^5D0到^7F2,^7F4的自发辐射几率和振子强度f（^5D0→^7F2）,f（^5D0→^7F4）。结果表明,材料的发射能级为^5D0→^7F1（590nm）,^5D0→^7F2（617nm）,^5D0→^7F4（698nm）,而且材料的结构对称性越差,跃迁戒律打破地越彻底,荧光发射越强。     

Effects of Thermal Treatment on the Structure and Properties of SiO2-TiO2 Gel Films on Silicon Substrates

Solution derived thin films of molar composition 90SiO₂-10TiO₂ deposited on c-Si substrates, for use as planar waveguides are characterized in terms of thickness and refractive index, by ellipsometry, as a function of isothermal heat treatments. The structural evolution of the films with thermal treatment is followed by infrared spectroscopy. The estimated average Si–O–Si intertetrahedral bond angle increases from 137°, at room temperature, to 144°, after heating at 900°C. The films should be annealed at T > 800°C, in order to release the residual stresses.     

Chemical component exchange and transport phenomena accompanying phase transformations in minerals and materials

Chemical component exchange and transport phenomena accompanying the multistage phase transformations of several silicate and aluminosilicate-phosphate glasses and borates as model systems are considered. It is demonstrated that the component transport limitations modify the role of chemical affinity influence and determine the sequence of new compound formation.The work was supported by grant P040703406 from the National Committee of Scientific Research of Poland.     

Correlation between the Dynamics of Nanoconfined Water and the Local Chemical Environment in Calcium Silicate Hydrate Nanominerals

Calcium silicate hydrates are members of a large family of minerals with layered structures containing pendant CaOH and SiOH groups that interact with confined water molecules. To rationalize the impact of the local chemical environment on the dynamics of water, SiOH- and CaOH-rich model nanocrystals were synthesized by using the continuous supercritical hydrothermal method and then systematically studied by a combination of spectroscopic techniques. In our comprehensive analysis, the ultrafast relaxation dynamics of hanging hydroxy groups can be univocally assigned to CaOH or SiOH environments, and the local chemical environment largely affects the H-bond network of the solvation water. Interestingly, the ordered “ice-like” solvation water found in the SiOH-rich environments is converted to a disordered “liquid-like” distribution in the CaOH-rich environment. This refined picture of the dynamics of confined water and hydroxy groups in calcium silicate hydrates can also be applied to other water-containing materials, with a significant impact in many fields of materials science.     

溶胶-凝胶法制备掺Sm3+的SiO2玻璃的结构及发光性能

利用溶胶-凝胶技术制备了掺不同量Sm3+和不同退火温度下的SiO2凝胶和玻璃,通过三维荧光光谱、激发光谱、发射光谱的测试,确定了Sm3+在SiO2凝胶玻璃中的最佳激发波长为360 nm,最强发射波长为610 nm,激发光谱的峰位置在360、393、464 nm处,发射光谱的峰位置在578、591、595、610、732nm处,分别归属于4G5/2-6H5/2、4G5/2-6H7/2、4G5/2-6H11/2跃迁,并证明当掺杂量达到1.15%时,Sm3+的发光最强,当Sm3+的掺杂量超过1.15%时,发生浓度猝灭效应.     

Tuning Chemical and Physical Properties of Phosphorus Corroles for Advanced Applications

Although the affinity of metallocorroles to axial ligands is quite low, this is not the case when the chelated element is phosphorus. This work is hence focused on the mechanism of ligand exchange of six-coordinate phosphorus corroles as a tool for affecting their chemical and physical properties. These fundamental investigations allowed for the development of facile methodologies for the synthesis of a large series of complexes and the establishment of several new structure/activity profiles that may be used to understand and predict spectroscopic features and for tailor-made modification of photophysical and electrochemical properties. This is exemplified by the facile access to complexes with terminal groups that are of large potential for practical applications based on click chemistry, optical imaging, and surface science.