凝胶体系中生物矿物生长的研究进展

近年来,生物矿化的模拟和仿生材料的研究十分引人注目.凝胶体系是模拟生物矿化的有效介质.本文综述了凝胶中羟基磷灰石、透钙磷石、磷酸钙等磷酸盐,文石、方解石、球霰石等碳酸钙,碳酸钡和草酸钙等生物矿物生长的研究进展,讨论了生长参数如凝胶种类、凝胶化学性质、吸附到凝胶表面的物质种类、介质pH、生长时间等对这些矿物晶体生长的影响,最后指出了该领域所面临的问题和将来的发展方向.     

PASP调控球形碳酸钙沉积过程研究

本文以聚天冬氨酸(PASP)为有机质模板,采用碳化法研究了水溶液中碳酸钙的沉积过程,利用FT-IR、XRD、SEM及粒度分析等方法对碳酸钙沉积样品晶型和晶貌进行了表征,并结合生物矿化的基本原理分析了晶体形成和成长变化过程.结果表明,有机质PASP能够调控碳酸钙沉积由方解石型转变为球霰石型,晶体形貌由菱形转变为球形,同时晶体平均粒径减小64.3;,且粒径分布收窄.主要原因是PASP模板中相邻两-COO-间距离与Ca2+的12配位体空间构型中的两个氧原子间距离相匹配,碳酸钙颗粒经过介晶形成了表面为小颗粒附着的球形晶体,PASP吸附在颗粒表面能够抑制晶体生长.     

LB膜模板诱导晶体取向生长

LB膜作为模板可诱导晶体取向成核和外延生长,生成的晶体材料具有独特的微观结构和优异的物理化学性能.这种方法对于生物矿化现象的研究以及新颖材料合成策略的设计等方面具有重要的启示意义.本文从LB膜诱导晶体取向生长的机理及利用等方面综述了该领域研究的最新进展.     

双尺寸胶体晶体的制备及其结构表征

采用垂直沉积法制备了双尺寸胶体晶体结构,并实现多种双尺寸SiO2胶体晶体结构的自组装.通过场发射扫描电子显微镜(FE-SEM)对胶体晶体的结构及排列方式进行测试分析.对双尺寸胶体晶体的生长过程进行探讨,研究大小胶体球的粒径比及体积比对结构的影响规律.研究结果表明大小球粒径比过小时,双尺寸胶体晶体排列结构有序性差.增大大胶体球的粒径时,合成相同双尺寸胶体晶体结构所对应的大小胶体球体积比增大.     

两株嗜冷碳酸钙矿化菌对大理石表面修复效果研究

细菌诱导的矿化沉积是一种有效修复和保护石质文物的方法.为探究生物矿化法应用于寒冷地区石质文物表面的修复效果,本文在黄龙高寒钙华沉积区分离到2株具高产碳酸酐酶(CA)活性的嗜冷型细菌菌株,并在大理石试件表面进行诱导矿化沉积.采用pH计、SEM、XRD等仪器,通过对矿化沉积过程中pH值、试件表面矿化沉积变化量、试件表面矿化沉积物的晶型晶貌、试件表面吸水性与透气性、耐酸度等的测定来表征嗜冷型碳酸酐酶产生菌在大理石试件表面矿化沉积的修复效果.结果表明,无论是存活菌还是灭活菌都在大理石试件表面生成了致密的碳酸钙矿化层,均为方解石晶型,形貌受菌体调控,活菌生成的矿化层更为均一和致密,长期作用比短期作用效果更明显,具有矿化层的试件在吸水性、透气性和耐酸度上都体现出更具防腐蚀的能力.其结果可为石质文物的修复提供一定的理论依据.     

胶体晶体自组装常用方法的研究进展

胶体自组装是制造大面积胶体晶体的高效方法,对制备各种功能胶体晶体材料具有十分重要的意义,在微纳制造、新材料、能源、医学等领域有巨大的应用潜力.对胶体自组装过程中涉及的各种作用力进行了详细分析,归纳了胶体晶体自组装的基本方法.面向制造大面积胶体晶体,阐述了几类代表性的新型胶体晶体自组装方法,包括温度辅助、模板辅助、表面活性剂辅助、旋涂法与界面转移相结合等,分析了不同方法的影响因素、优缺点和未来的改良方向,并介绍了在完整单层膜基础上制造三维胶体晶体的工艺方法.为提高胶体晶体制造质量和效率、拓宽胶体自组装技术的应用提供必要参考.     

水垢晶体的形成及变化规律研究

加热含有0.001 mol/L的CaCl2和NaHCO3的水样,在保持蒸发与补水速度相同的条件下,利用扫描电子显微镜(SEM)研究碳钢挂片表面沉积水垢颗粒的生长过程,聚集形态和晶体结构的变化.结果表明:挂片表面首先析出无规则聚集的球状和片状颗粒;15 min后微小的球状或片状颗粒出现定向排列的趋势,形成表面十分粗糙的针棒状堆积体,其轴向生长速度达1.0～1.5 μm/min;随着蒸发时间的延长,在加热2 h时,针棒状堆积体由根部开始晶化,逐步形成棱角分明的六棱柱状晶体.晶体表面也会吸附新生球形颗粒不断的沉积,同时在挂片的表面还会形成许多直径约为2 μm,厚度约0.1 μm的六边形片状球霰石颗粒,片层颗粒无规则的相互支撑和聚集,部分颗粒以直立方式生长.6 h后已形成的六棱柱状晶体颗粒的顶部形态开始发生变异,形成顶端带有数十根针状分枝的孪生晶体.而部分球霰石颗粒的聚集体在加热3 h后逐步向斜六面体方解石转变.     

具有大尺寸(001)晶面的有机DAST晶体生长与THz波产生

具有大尺寸(001)晶面的有机晶体DAST(4-(4-二甲基氨基苯乙烯基)甲基吡啶对甲苯磺酸盐)的生长对构建高强度宽带THz辐射源具有重要意义,但也极具挑战性.本论文采用斜板法结合缓慢冷却技术,研究了生长液浓度对晶体长宽比的影响.通过对生长条件的精确控制,生长出了具有大面积(001)晶面的DAST晶体.经检测,晶体具有良好的表面质量.晶体在无需表面抛光的条件下,实现了单周期太赫兹脉冲输出,光-太赫兹转换效率达到0.66;.     

DNA模板调控纳米无机材料生长

以DNA为模板诱导纳米无机晶体的生长是近年来一个新的研究方向.DNA模板具有完善和严密的分子识别功能,使其组装过程具有高度的选择性.通过人为控制DNA的形状、长度和序列,可以制备出不同结构的纳米功能材料.本文讨论了DNA模板诱导硫化镉、四氧化三铁、硫酸钡、氯化镁和二氧化硅等纳米无机晶体的生长.     

以NH4Cl为矿化剂水热合成ZnO自组装微纳米结构

采用NH4Cl为矿化剂,以金属锌片为锌源,水热合成出多种不同形貌的ZnO微纳米结构.其中ZnO纳米棒及铅笔都沿[001]方向生长,结晶性很好.在水热条件下, ZnO纳米棒通常倾向于自组装成花状的结构.本文从鲍林电负性的角度揭示了形成这些微纳米结构的化学反应机理,分析了Cl 和NH+4在这些微纳米结构形成过程中所起的作用.研究结果表明:温度和填充度对ZnO纳米结构的结晶性和形貌也有重要的影响.当温度从150 ℃升至180 ℃时,ZnO纳米晶的结晶性明显更好.当填充度从60;增加到80;时,除了形成ZnO纳米棒花状自组装结构以外,在金属锌片表面还趋于生成大量的ZnO微球.     

掺杂方式对纳米二氧化钛性能的影响研究

对近年来掺杂改性纳米二氧化钛的研究进行了综述,并且详细论述了金属离子掺杂、非金属离子掺杂以及双元素掺杂这三类掺杂方式对纳米二氧化钛的结构相变,光催化性能等方面的影响。     

A Comprehensive Optical Second Harmonic Generation Study of the Non-Centrosymmetric Character of Biological Structures

The application of optical second harmonic generation (SHG) to the study of non-centro-symmetry in 71 α-amino acids, 22 dipeptides. 6 tripeptides. 16 proteins, and 5 viruses is reported. All α-amino acids except α-glycine, all peptidcs containing at least one enantiomeric α-amino acid residue, and all proteins and viruses are found to be non-centrosymmetric. Of the 22 racemic α-amino acids investigated, 19 form centrosymmetric crystalline racemates. DL-alanine and DL-norleucine form non-centrosymmetric racemates whereas m-glutamic acid does not form racemic crystals except when hydrated. These results lead us to suggest that non-centrosymmetry and its consequences (i.e., allowable piezoelectricity and possible pyroelectricity) is an essential and universal property of all biological systems. Furthermore, the concept of polarization homeostasis (i.e., biomolecules in vivo have a macroscopic equilibrium polarization in which the polarization ≠ 0) is proposed as a basic biological phenomenon and shown to be consistent with the dominance of one enantiomeric configuration of α-amino acids in nature, natural selection and mutationally induced molecular diseases.     

Effect of chlorine ion on the crystalline and photocatalytic activity of BiOCl for the degradation of Rhodamine B

Two kinds of layer‐structured BiOCl photocatalysts (BiOCl‐01 and BiOCl‐02) were synthesized using NaBiO₃ and HCl as the raw materials, and KCl as the Cl⁻ conditioning agent. These photocatalysts were characterized by X‐ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and ultraviolet visible diffuse reflectance spectra (DRS) measurements. The effects of chlorine ion in the reaction solutions on the crystalline of BiOCl and photodegradation of Rhodamine B (RhB) under 365 nm and 530 nm monocharomatic light irradiation were investigated. The XRD spectra confirmed the formation and purity of BiOCl photocatalysts, revealed that Cl⁻ ion existed in the preparation solution restrained the growth of BiOCl and influenced the surface configuration. The TEM and HRTEM analysis gave the similar results with XRD. The band gaps of BiOCl‐01 and BiOCl‐02 were estimated about 3.19 and 3.29 eV, respectively. The photocatalytic degradation results of RhB under 365 nm showed that the photocatalytic activity of BiOCl‐02 was better than that of BiOCl‐01, and the main active species were h⁺ and . Meanwhile, the photosensitized results of RhB under 530 nm indicated that the photosensitized activity of BiOCl‐01 and BiOCl‐02 was similar, and the main active species was .     

离子注入技术在山东蓝宝石优化处理中的应用

本文报道了用离子(Be~(2+)和Ti~(4+))注入技术优化处理山东蓝宝石的工作.对处理前后样品一系列测试和实验的结果表明:(1)样品经过离子注入处理后,表面光泽明显增强,表面光洁度保持良好;(2)山东蓝宝石注入Be~(2+)后,颜色较处理前更深,说明Be~(2+)虽然不是致色离子,但可对蓝宝石颜色产生明显的影响;(3)注入Ti~(4+)后,山东蓝宝石的颜色变浅变艳了.进一步证明了山东蓝宝石的颜色深是由于Fe~(2+)浓度高,同时Ti~(4+)浓度相对太低所致,对今后山东蓝宝石乃至其它宝石的优化处理提供了新的思路和方法.     

Formation and crystal structure of 1-methyl-2-phenylindolizine-3-acetonitrile

1-Methyl-2-phenylindolizine-3-acetonitrile was unexpectedly obtained in the reaction of 1-methyl-2-phenylindolizine-3-thioaldehyde with cyanide ions. Its structure was determined by IR, ¹H NMR, MS, elemental analyses, and X-ray crystallography. Colorless regular prism shaped crystals of C₁₇H₁₄N₂ crystallize in the space group C2/c with cell dimensions a = 12.956(3) Å, b =10.516(2) Å, c = 20.429(4) Å, and = 90°, = 104.98(3)°, = 90°, V =2688.7(9) ų, D _calc =1.217 Mg/m³, and Z = 8.     

离子轰击对准直碳纳米管生长的影响

利用负偏压增强热丝化学气相沉积系统,在辉光放电的情况下制备出准直碳纳米管,并用扫描电子显微镜研究了不同负偏压对准直碳纳米管生长的影响.结果表明随着负偏压的增大,准直碳纳米管的平均直径减小,平均长度增大.由于辉光放电的产生,在衬底表面附近形成阴极鞘层,以及在阴极鞘层内形成大量的离子和在衬底表面附近形成很强的电场导致了离子对衬底表面的强烈轰击.最后,分析和讨论了离子的轰击对准直碳纳米管生长的影响.     

Crystal structures and physical chemical properties of nedocromil zinc heptahydrate and nedocromil magnesium pentahydrate

The crystal structure of one of the hydrated forms of nedocromil zinc, the heptahydrate, and that of one of the hydrated forms of nedocromil magnesium, the pentahydrate, have been determined. Crystal data: zinc salt,a=11.769(3),b=7.000(2),c=14.022(4); Å; =105.35(2)°; monoclinic, space groupP2₁,Z=2;magnesium salt,a=7.460(1),b=10.233(2),c=13.934(2) Å, =86.54(1)°, =79.74(1)°, =77.25(1)°; triclinic, space groupP,Z=2. The major differences between the crystal structures are the environment and bonding of the cations. The zinc cation is linked directly to the carbonyl oxygen of the pyridone ring and to five water molecules in an octahedral coordination. The magnesium cation is linked directly to two different carboxyl oxygens, one in asyn orientation and the other in ananti orientation in different asymmetric units and to four water molecules in an octahedral coordination. Thermal analytical methods show that the zinc salt hydrate undergoes thermal dehydration at lower temperatures than the magnesium salt hydrate. This behavior may be related to the presence of continuous water channels in the zinc salt hydrate and to their absence in the magnesium salt hydrate. For each salt hydrate 1 mole of water is lost at a higher temperature than the other waters.     

Short-wavelength upconversion luminescence of Yb/Tm co-doped glass ceramic containing SrF2 nanocrystals

The preparation process and upconversion luminescence properties of the Yb³⁺ and Tm³⁺ co-doped glass ceramic containing SrF₂ nanocrystals were investigated. In the glass ceramic, the SrF₂ nanocrystals were embedded uniformly in the glass matrix. The Yb³⁺ and Tm³⁺ ions could be enriched into the precipitated SrF₂ nanocrystalline phase, which provide much lower phonon energy than the glass matrix. The glass ceramic exhibited much stronger upconversion luminescence from ultraviolet to visible than the precursor glass. The upconversion luminescence mechanisms were mainly attributed to Yb³⁺-Yb³⁺ cooperative upconversion, Yb³⁺-Tm³⁺ energy transfer and Tm³⁺-Tm³⁺ cross relaxation.     

二次退火制备Ⅲ-Ⅴ族半导体量子点

利用离子注入法在一块Si(001)衬底上注入了In+和As+,注入能量分别为210keV,150keV,注入剂量6.2×1016cm-2,8.6×1016cm-2,另一块Si(001)衬底上注入Ga+和Sb+,注入能量分别为140keV,220keV,注入剂量分别为8.2×1016cm-2,6.2×1016cm-2,然后对样品分别经过一次退火和二次退火处理制备出了Si基量子点材料。用透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)观察了退火后量子点截面像,用PL探测量子点的光致发光谱,发现经二次退火生长的量子点微晶格结构和Si衬底损伤的修复均明显优于一次退火。     

Eu3+扩散钨酸铅晶体(PbWO4)光学性能研究

利用离子扩散法对下降法生长PbWO4晶体进行Eu3+扩散,通过透射光谱、荧光光谱、光产额和衰减时间的测试,研究了Eu3+扩散对PbWO4晶体的光学性能的影响.结果表明:Eu3+扩散PbWO4晶体可明显改善在350 nm波段的透过率,荧光光谱主峰为430 nm,且发光强度得到增强,在1000 ns的积分时间门宽内光产额为46 pe/MeV,衰减时间为6.5 ns.