溶胶处理对硅灰石表面性质的影响

本工作用锡和锌两种溶胶对硅灰石进行表面处理。用酸碱测定、X-射线光电子能谱(XPS)、傅里叶变换红外光谱(FT-IR)、粒度分析、比表面测定和扫描电子显微分析(SEM)等方法研究了溶胶处理对硅灰石表面化学性质和物理性质的影响情况。结果表明经过溶胶处理,锡或锌是以氧化物的形式包覆在硅灰石的表面,使得硅灰石的表面组成、形貌和酸碱性都发生了变化。     

纳米复合钛白的研制

以硅灰石为核心,采用化学沉淀法在其表面均匀包覆一层纳米TiO₂,形成了硅灰石复合钛白。包覆过程中硅灰石的预处理是关键一步。经XRD,IR,SEM,TEM和XPS对复合钛白进行表征,结果表明,包覆完全的硅灰石复合钛白性能与钛白粉相当。     

PDP用BaMgAl10O17：Eu蓝粉的表面包覆研究

采用硅酸钠水解法对BaMgAl10O17∶Eu^2＋（BAM）蓝粉进行了表面包覆,通过XRD,TEM和AES等分析手段对包膜荧光粉物相、微观形貌及表面元素进行分析。研究结果表明,BAM蓝粉表面包覆了一层厚薄均匀、表面光滑且致密度高的硅氧化合物无机膜,膜厚约为16-20 nm。BAM蓝粉经包覆处理后,抗热劣化性能得以显著提高,在600℃煅烧1 h后,包膜BAM蓝粉的发光亮度和色坐标分别为91%和0.0609,明显优于未包膜蓝粉的75%和0.0633。     

PDP用BaMgAl10O17∶Eu蓝粉的表面包覆研究

采用硅酸钠水解法对BaMgAl10O17∶Eu2+(BAM)蓝粉进行了表面包覆, 通过XRD, TEM和AES等分析手段对包膜荧光粉物相、微观形貌及表面元素进行分析.研究结果表明, BAM蓝粉表面包覆了一层厚薄均匀、表面光滑且致密度高的硅氧化合物无机膜, 膜厚约为16～20 nm.BAM蓝粉经包覆处理后, 抗热劣化性能得以显著提高, 在600 ℃煅烧1 h后, 包膜BAM蓝粉的发光亮度和色坐标分别为91%和0.0609, 明显优于未包膜蓝粉的75%和0.0633.     

核壳结构磁性镁铝复合氧化物亚微米粒子的制备与表征

首先采用溶剂热法制备粒径均匀分散性良好的Fe3O4亚微米粒子,在对其包覆上一层碳膜进行表面修饰后,采用共沉淀法将硝酸根插层LDHs包覆到磁性粒子的表面,然后500℃焙烧2 h得到磁性镁铝复合氧化物亚微米粒子。这种磁性镁铝复合氧化物亚微米粒子具有以镁铝复合氧化物为壳层,Fe3O4为核的核壳结构,其中壳层厚度为20 nm左右,对其进行二次包覆后壳层厚度可达到50 nm左右,并可以方便的通过重复包覆焙烧过程进行调节,从而实现磁性镁铝复合氧化物亚微米粒子的控制制备。同时,磁性镁铝复合氧化物亚微米粒子具有较强的磁性,其比饱和磁化强度为23.3 emu·g-1,对其进行二次包覆并焙烧后为20.1 emu·g-1。     

Y_2O_3∶Eu荧光粉表面包覆In_2O_3的研究

采用高温固相法合成了FED用Y2O3∶Eu红色荧光粉,为提高其导电性,采用表面成膜包覆法对其进行了In2O3包膜研究。通过XRD,Zeta电位,SEM及低压光谱分析等检测手段分析了包膜前后Y2O3∶Eu的晶体结构、电位、形貌与发光性能,探索了包膜工艺。结果表明:在Y2O3∶Eu表面包覆3%的In2O3能有效改善荧光粉的发光亮度,这种改善的可能原因是包覆In2O3改善了Y2O3∶Eu晶粒表面的导电性。     

Y2O3:Eu荧光粉表面包覆In2O3的研究

采用高温固相法合成了FED用Y2O3：Eu红色荧光粉，为提高其导电性，采用表面成膜包覆法对其进行了In2O3包膜研究。通过XRD，Zeta电位，SEM及低压光谱分析等检测手段分析了包膜前后Y2O3：Eu的晶体结构、电位、形貌与发光性能，探索了包膜工艺。结果表明：在Y2O3：Eu表面包覆3％的In2O3能有效改善荧光粉的发光亮度，这种改善的可能原因是包覆In2O3改善了Y2O3：Eu晶粒表面的导电性。     

原位包覆纳米碳提升钴锰氧化物材料储锌性能

钴锰氧化物（CMO）具有安全无毒、价格便宜、活性位点多等优点,是极具潜力的锌离子电池正极材料.目前,充放电过程中电极材料溶解造成的结构坍塌成为限制其发展的瓶颈问题.本工作提出了一种原位碳包覆的方法来缓解CMO的溶解问题,在提高材料容量的基础上成功地延长了其循环寿命.通过简单的一步水热方法,成功制备了纳米碳（nC）包覆的钴锰氧化物（CMO@C）材料,X射线衍射（XRD）、X射线光电子能谱（XPS）、拉曼光谱（Raman）等表征证明,nC包覆层的引入并没有改变CMO材料的基本组分结构.而且,相较于CMO,CMO@C的电荷转移阻力更小,离子扩散更快,表现出更优异的电化学性能.在0.5 A·g^-1的电流密度下,CMO@C显示出271.9 mAh·g^-1的比容量,且经过1000圈循环后,材料的比容量没有发生衰减,性能大大优于CMO对比样品（103.7 mAh·g^-1;130圈失效）.由此可见,纳米碳包覆层可同时提升CMO的储锌容量和循环寿命.本工作为双金属氧化物正极材料的优化改性提供了新的策略.     

Mg2Ni0.75Cu0.25-Mg1.76体系的合成及氢化过程的初步研究

Leilly^[1]、Rudmen^[2]和本研究组^[3]分别对Mg₂Ni-xMg,Mg₂Cu-xMg体系进行了研究,巳发现Mg₂Ni或Mg₂Cu的存在对镁的氢化,释氢过程有催化作用,并描述了二元合金Mg₂Ni,Mg₂Cu对Mg的吸、放氢过程的催化氢化、脱氢模型。但有关三元合金对纯镁的吸、放氢催化性能研究,至今未见报道。我们合成了在基质镁粒表面包覆Mg₂Ni_0.75Cu_0.25的新型材料,并研究此三元合金表面对所包覆的Mg核与H₂之间反应的影响。     

水稳定的镁掺杂ZnO量子点:一锅法合成及细胞成像应用

一锅法合成了镁掺杂的ZnO量子点,利用APTES对其进行表面包覆,并采用XRD、TEM、UV-Vis、PL和FTIR等对材料进行了表征。结果表明镁掺杂能明显增强荧光发光强度,在合适的掺杂浓度(30%)下其量子产率由11%增加到33%。通过APTES的表面包覆使镁掺杂的ZnO量子点具有良好的水溶性和荧光稳定性,可用于MCF-7细胞成像研究。     

The Role of the Relative Dye/Photocatalyst Concentration in TiO2 Assisted Photodegradation Process

Despite photocatalytic degradation is studied generally focusing the catalyst, its interaction with the contaminant molecule plays a fundamental role in the efficiency of that process. Then, we proposed a comparative study about the photodegradation of two well‐known dyes, with different acidity/basicity – Methylene Blue (MB) and Rhodamine B (RhB), catalyzed by TiO₂ nanoparticles, varying both dye and photocatalyst concentrations. The results showed that the amphoteric character of MB molecules, even in a range of concentration of 5.0–10.0 mg L^?1, did not imply in pH variation in solution. Therefore, it did not affect the colloidal behavior of TiO₂ nanoparticles, independent of the relative dye/catalyst concentration. The acid–base character of RhB influenced the resultant pH of the solution, implicating in different colloidal behavior of the nanoparticles and consequently, in different degradation conditions according to dye concentration. As the isoelectric point of TiO₂ is between the pH range of the RhB solutions used in this study, from 1.0 to 7.5 mg L^?1, the resultant pH was the key factor for degradation conditions, from a well dispersed to an agglomerated suspension.     

An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water

Inorganic calcium carbonate precipitation from natural seawater and saline water at various pH values was carried out experimentally. The results show the clear positive relationships between boron concentration and δ11B of inorganic calcium carbonate with the pH of natural seawater and saline water. However, the variations of boron isotopic fractionation between inorganic calcite and seawater/saline water with pH are inconsistent with the hypothesis that B(OH)4- is the dominant spe-cies incorporated into the biogenic calcite structure. The isotopic fractionation factors α between synthetic calcium carbonate precipitate and parent solutions increase systematically as pH increases, from 0.9884 at pH 7.60 to 1.0072 at pH 8.60 for seawater and from 0.9826 at pH 7.60 to 1.0178 at pH 8.75 for saline water. An unusual boron isotopic fractionation factor of larger than 1 in synthetic calcium carbonate precipitated from seawater/saline water at higher pH is observed, which implies that a substantial amount of the isotopically heavier B(OH)3 species must be incorporated preferentially into synthetic inorganic carbonate. The results propose that the incorporation of B(OH)3 is attributed to the formation of Mg(OH)2 at higher pH of calcifying microenvironment during the synthetic calcium carbonate precipitation. The preliminary experiment of Mg(OH)2 precipitated from artificial seawater shows that heavier 11B is enriched in Mg(OH)2 precipitation, which suggests that isotopically heavier B(OH)3 species incorporated preferentially into Mg(OH)2 precipitation. This result cannot be applied to explain the boron isotopic fractionation of marine bio-carbonate because of the possibility that the unusual environment in this study appears in formation of marine bio-carbonate is infinitesimal. We, however, must pay more attention to this phenomenon observed in this study, which accidentally appears in especially natural environment.     

Decay of H<Subscript>2</Subscript>O<Subscript>2</Subscript> under the action of the colloidal catalyst based on iron(III) oxides in a neutral medium

The catalytic activity of the colloidal catalyst based on iron(III) hydroxide was studied in the decomposition of H₂O₂ in a neutral medium (pH 6.7). A colloidal micellar solution of iron(III) hydroxide after preparation was kept at 19–20 °С for 2 or 20 h without additives or with C₂H₅OH additives. The decomposition of H₂O₂ under the action of the colloidal catalyst (20 h) proceeds via the first-order reaction with the decay rate constant k_d = 1.26?10^–4 s^–1, whereas the decay rate of the first-order reaction is k_d = 0.77?10^–4 s^–1 for the colloidal catalyst (2 h) prepared in the presence of C₂H₅OH.     

Bioactivity Performance of Pure Mg after Plasma Electrolytic Oxidation in Silicate-Based Solutions

The biodegradable metals, including magnesium (Mg), are a convenient alternative to permanent metals but fast uncontrolled corrosion limited wide clinical application. Formation of a barrier coating on Mg alloys could be a successful strategy for the production of a stable external layer that prevents fast corrosion. Our research was aimed to develop an Mg stable oxide coating using plasma electrolytic oxidation (PEO) in silicate-based solutions. 99.9% pure Mg alloy was anodized in electrolytes contained mixtures of sodium silicate and sodium fluoride, calcium hydroxide and sodium hydroxide. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), contact angle (CA), Photoluminescence analysis and immersion tests were performed to assess structural and long-term corrosion properties of the new coating. Biocompatibility and antibacterial potential of the new coating were evaluated using U2OS cell culture and the gram-positive Staphylococcus aureus (S. aureus, strain B 918). PEO provided the formation of a porous oxide layer with relatively high roughness. It was shown that Ca(OH)₂ was a crucial compound for oxidation and surface modification of Mg implants, treated with the PEO method. The addition of Ca²⁺ ions resulted in more intense oxidation of the Mg surface and growth of the oxide layer with a higher active surface area. Cell culture experiments demonstrated appropriate cell adhesion to all investigated coatings with a significantly better proliferation rate for the samples treated in Ca(OH)₂-containing electrolyte. In contrast, NaOH-based electrolyte provided more relevant antibacterial effects but did not support cell proliferation. In conclusion, it should be noted that PEO of Mg alloy in silicate baths containing Ca(OH)₂ provided the formation of stable biocompatible oxide coatings that could be used in the development of commercial degradable implants.     

Study of the colloidal stability of an amphoteric latex

We have studied the colloidal stability of an amphoteric latex (–COOH and NH ₂ surface groups) with a low-angle light scattering technique (nephelometry). Measurements were carried out at different pH values and electrolyte concentrations (NaCl or CaCl ₂). The results show a behaviour in agreement with DLVO theory when the pH of the medium is below the isoelectric point (i.e.p.) of the latex: at low ionic strengths the latex is stable, but it becomes completely unstable and coagulates when electrolyte concentration goes over a particular value (the critical coagulation concentration). However, when pH is raised above the isoelectric point, the latex is completely stable even at high electrolyte concentrations, showing a behaviour clearly opposite to the theory. This could be explained by means of an additional short-range repulsive "hydration force" due to the structure of water molecules that accompany hydrated cations around the hydrophilic latex surface. The morphology and electrical properties of the latex surface have been studied by different methods: dynamic light scattering, electrophoretic mobility, potentiometric and conductometric titrations.     

Comparison of the Structural Information on Sol-Gel Systems Provided by Pyrene Labeled Fluorescent Probes

The influence of the acid catalyst concentration on the structural evolution of a sol-gel system was studied by doping TEOS based starting solutions with two fluorescent probes: a polystyrene chain (M _n =1700) and a much shorter alkane chain (M=172), both of them labeled at both ends with 1-pyrenyl. For this purpose, each probe was incorporated in two TEOS∶H₂O∶C₂H₅OH mixtures (molar ratios 1∶4∶1), one at pH 1.2 and the other at pH 2.5 (respectively below and above the isoelectric point of silica). Very low concentrations of the probes were used (≤10⁻⁶ M), so the pyrene dimmers and excimers were formed only intramolecularly. The ratios of excimer to monomer fluorescence intensities at excitation wavelength of 360 nm (where mainly the ground state pyrene dimmers are excited) were studied as a function of time. Different evolutions of these ratios were observed, which allowed us to predict that the silica structure developsvia the formation of primary particles, even at pH values below the isoelectric point of silica, where it is not possible to directly detect their formation.     

Mg(BO2)2在MgCl2水溶液中的相平衡与化学平衡

借助拉曼光谱和X射线衍射(XRD)检测手段,对Mg(BO_2)_2在MgCl_2水溶液中水解的固液相平衡与物种化学平衡规律进行了研究。结果表明,MgCl_2对Mg(BO_2)_2的溶解转化、多硼氧配阴离子的物种分布有很大影响:(1)随着MgCl_2浓度从0达到饱和,Mg(BO_2)_2的表观饱和浓度从0.79%增加到1.96%,pH值从9.96降到6.27;(2)Mg(BO_2)_2在纯水中水解形成固相Mg_2B_6O_(11)·15H_2O和Mg(OH)_2,在MgCl_2溶液中形成固相Mg_2B_6O_(11)·15H_2O和Mg_3Cl_2(OH)_4·4H_2O;(3)Mg(BO_2)_2在纯水中水解,硼的物种主要为B_4O_5(OH)_4~(2-)和B_3O_3(OH)_4~-,分别占液相总硼含量的49.81%和19.54%。在MgCl_2饱和溶液中,主要为B_3O_3(OH)_4~-和B_5O_6OH)_4~-,分别占液相总硼含量的44.57%和40.00%。     

Formation and transformation of Mg(OH)2 in anodic coating using FTIR mapping

FTIR microscopic mapping was used to investigate the surface distribution of Mg(OH)₂ on anodic coatings. The results indicated Mg(OH)₂ was formed accompanying with micro-arc sparking and the amount of Mg(OH)₂ was related to the intensity of sparking, which depends on the applied voltage. The distribution and amount of Mg(OH)₂ varied with immersion time in 3.5 wt.% NaCl solution. The transformation process of anodic coatings was researched by FTIR microscopic mapping and smart map. The Cl^? could be absorbed on the surface of anodic coatings where Mg(OH)₂ is present and promote Mg(OH)₂ to transform into the soluble magnesium salt MgCl₂.     

刷状结构的阳离子性接枝微粒QPDMAEMA/SiO2对牛血清白蛋白的吸附特性

以微米级硅胶微粒为基质, 通过接枝聚合和大分子反应, 制备了具有刷状结构的阳离子性接枝微粒, 深入研究了其对牛血清白蛋白(BSA)的强吸附能力、吸附机理和吸附热力学. 首先使含叔胺基团的单体甲基丙烯酸二甲基氨基乙酯(DMAEMA)在硅胶微粒表面发生接枝聚合, 制得接枝微粒PDMAEMA/SiO₂, 然后以氯乙胺为试剂, 使接枝大分子PDMAEMA链中的叔胺基团发生季铵化反应, 获得了具有刷状结构的阳离子聚电解质的功能接枝微粒QPDMAEMA/SiO₂. 测定了微粒QPDMAEMA/SiO₂的zeta 电位, 实施了对BSA的等温吸附实验, 考察了介质pH值、离子强度及温度对吸附作用的影响, 研究了吸附热力学. 研究结果表明, 功能接枝微粒QPDMAEMA/SiO₂ 比接枝微粒PDMAEMA/SiO₂ 具有更高的zeta 电位, 在静电相互作用驱动下, 微粒QPDMAEMA/SiO₂对BSA具有很强的吸附能力. 吸附容量随介质pH值的增大呈现先增大后减小的变化趋势,当pH值等于BSA的等电点(pI=4.7)时, 具有最高的吸附容量(高达112 mg·g^-1). 以等电点为界, 离子强度对吸附容量会产生完全相反的影响作用: 当介质pH值小于BSA的等电点时, 电解质浓度增大, 吸附容量增高; 当介质pH值等于BSA的等电点时, 吸附容量几乎不随电解质的浓度发生变化. 吸附过程熵值减小而且放出热量,是一个焓驱动的吸附过程.     

Studies on zero point of charge and intrinsic ionization constant of Zn−Mg−Al hydrotalcite-like compounds

The zero point of charge (ZPC) and the intrinsic ionization constant ( % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavTnhis1MBaeXatLxBI9gBae % bbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY-Hhbbf9v8qqaqFr % 0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8 % frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaadaaakeaacqWG % lbWsdaqhaaWcbaGaeeyyaegabaGaeeyAaKMaeeOBa4MaeeiDaqhaaa % aa!304C! K_a^int K_{\rm a}^{{\rm int}} ) of Zn-Mg-Al hydrotalcite-like compounds (HTlc) with the general formula [(Zn,Mg) _{1- x} Al _x (OH) ₂] ^{x +} [(OH,Cl) _x] ^{x -} were determined by potentiometric titration (PT). The variation of the ZPC and % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavTnhis1MBaeXatLxBI9gBae % bbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY-Hhbbf9v8qqaqFr % 0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8 % frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaadaaakeaacqWG % lbWsdaqhaaWcbaGaeeyyaegabaGaeeyAaKMaeeOBa4MaeeiDaqhaaa % aa!304C! K_a^int K_{\rm a}^{{\rm int}} with xwas investigated. For the colloidal particles possessing permanent charges, the ZPC determined by the PT method is the zero point of net charge (ZPNC). The ZPNC ( pH _ZPNC) values were 9.63 {[Zn _0.27Mg _0.36Al _0.37 (OH) ₂]Cl _0.13 (OH) _0.24 }, 9.68 {[Zn _0.13Mg _0.58Al _0.29 (OH) ₂]Cl _0.12 (OH) _0.17 }, 9.67 {[Zn _0.17Mg _0.54Al _0.29 (OH) ₂]Cl _0.16 (OH) _0.12 },10.16 {[Zn _0.08Mg _0.67Al _0.25 (OH) ₂]Cl _0.17 (OH) _0.08}, 10.33 {[Zn _0.16Mg _0.60Al _0.24 (OH) ₂] Cl _0.16 (OH) _0.08} and 10.60 {[Zn _0.19Mg _0.60Al _0.21 (OH) ₂] Cl _0.15 (OH) _0.06}; the intrinsic ionization constants % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavTnhis1MBaeXatLxBI9gBae % bbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY-Hhbbf9v8qqaqFr % 0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8 % frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaadaaakeaacqqG % WbaCcqWGlbWsdaqhaaWcbaGaeeyyaeMaeeOmaidabaGaeeyAaKMaee % OBa4MaeeiDaqhaaaaa!329E! pK_a2^int {\rm p}K_{{\rm a2}}^{{\rm int}} of the same HTlc samples were 10.31, 10.44, 10.44, 11.02, 11.19 and 11.54. With decreasing x, ZPNC and % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfKttLearuavTnhis1MBaeXatLxBI9gBae % bbnrfifHhDYfgasaacH8srps0lbbf9q8WrFfeuY-Hhbbf9v8qqaqFr % 0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qqQ8 % frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaadaaakeaacqWG % lbWsdaqhaaWcbaGaeeyyaeMaeeOmaidabaGaeeyAaKMaeeOBa4Maee % iDaqhaaaaa!3137! K_a2^int K_{{\rm a2}}^{{\rm int}} of HTlc increased, and the acidity of the HTlc samples decreased.