Mineralization of oriented nano hydroxyapatite in photopolymerized polyacrylamide gel matrix

Polyacrylamide hydrogel is a biomaterial and nondegradable water based polymer which is used as tissue filler. Mineralization of hydroxyapatite (HAp) in a UV polymerized acrylamide gel matrix was investigated by varying the concentration of precursors and pH in the range 8, 9 and 10. During polymerization, diammonium hydrogen phosphate ions were impregnated in the gel matrix and subsequently, immersed in the calcium nitrate solution. Thin laminated macroporous structures, embedded with nanospheres and ribbons of HAp were mineralized. The HAp was found to be oriented along c‐axis, which could lead to the preferential binding of the acidic proteins on it's surface. In addition, there was an enlargement of pore sizes with an increase in pH. The laminated structures showed resorbable nature whereas, flake like structures obtained at higher concentrations were found to be bioactive. This composite could be an alternative to the use of silicone gel, to avoid long term risk of fibrosis and migration when implanted. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

FTIR,powder XRD,TEM and dielectric studies of pure and zinc doped nano‐hydroxyapatite

Hydroxyapatite, Ca₁₀(PO₄)₆(OH)₂ or HAP, is an important bio‐material, which is having application in bone implants and dentistry. In the present study, zinc doped nano‐hydroxyapatite (Zn‐HAP) was synthesized via chemical precipitation route using surfactant mediated approach. The doping of zinc was confirmed by EDAX. The powder X‐ray diffraction (XRD) pattern revealed the typical hydroxyapatite pattern with broadening and extra peaks were observed for higher concentration. The average crystallite size was calculated by applying the Scherrer's formula to powder XRD pattern and was found in the range of 16 to 33 nm. The morphology of synthesized nano‐particles was also confirmed using TEM. FTIR spectroscopy was used to confirm the presence of various bonds. The dielectric study was carried out at room temperature within the frequency range from 10² Hz to 10⁷ Hz and the variations of dielectric constant with frequency of applied field as well as with the concentration of zinc were studied. It was found that as the concentration of zinc increased the dielectric constant increased. The variations of dielectric loss and a.c. conductivity with frequency of applied field were studied. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

液相沉淀法制备硅酸镥粉体的研究

将氯化镥溶液滴加至硅酸钠溶液中制备出的沉淀,经过滤、陈化及烘干后对其进行XRD成分及SEM显微形貌的分析,结果表明粉体除少量杂质外,其主要成分都是由硅酸镥构成,而经烘干研磨后的粉体颗粒呈球形,将采用液相沉淀法与固体混合焙烧法所制备出的两种粉体进行了对比发现,采用前者可以不经高温煅烧就可以得到较纯硅酸镥,而后者在较高温度下煅烧后仍有大量原料残余,而且从颗粒尺寸、粉体形状以及烧结性能上来液相法制备出的粉体看都优于固相法.     

A novel thermolysis method of colloidal protein precursors to prepare hydroxyapatite nanocrystals

A novel thermolysis method of colloidal protein precursors is introduced to prepare hydroxyapatite (HAP) nanocrystals. The colloidal protein precursors are sonochemically synthesized from saturated Ca(OH)₂ aqueous solution, Ca(H₂PO₄)₂ aqueous solution and bovine serum albumin (BSA) molecules. The colloidal protein precursors are amorphous and composed of 15‐90 nm near spherical calcium phosphate nanoparticles and BSA molecules. The particle size analysis shows the volume particle size distribution is from 9.0 nm to 222.6 nm and the volume‐averaged particle size is 45.8 nm. During the calcination procedure BSA molecules are burningly removed and the HAP nanocrystals can be obtained at 500 °C. The effects of BSA concentration on the properties of samples are discussed. Results show that BSA combustion can promote the transformation of crystalline HAP from amorphous material. Moreover, the increase of BSA concentration reduces the crystalline sizes of HAP crystals and the crystallinity of product. With BSA concentration of 5 g/L, the obtained HAP nanocrystals are mainly 25∼100 nm similar spherical nanoparticles besides some 40∼70 nm×75∼150 nm short rod‐like crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

LiAlO2衬底上ZnO薄膜的溶胶-凝胶法制备和表征

采用溶胶凝胶法在LiAlO2(302)衬底上制备了ZnO薄膜.用X射线衍射(XRD)和扫描电镜(SEM)对样品的结构和形貌进行了表征.XRD结果表明,随着热处理温度的升高(350℃、450℃、550℃、600℃、800℃),所得到的薄膜分别为单相ZnAl2O4(350℃),ZnAl2O4和ZnO的混合相(450℃)以及单相的ZnO(550℃、600℃、800℃),并且ZnO薄膜c轴择优取向的生长趋势随温度升高相应明显.SEM图像显示,随着热处理温度的升高,ZnO薄膜的粒径相应变大.     

Phase and morphology evolution of vaterite crystals in water/ethanol binary solvent

Keeping stability is important for metastable vaterite to be applied. In this work, crystal evolution of vaterite in water/ethanol binary solvent (WEBS) was investigated. Phase identification was confirmed by XRD measurement. It is found that the stability of vaterite is sensitive to the concentration of surplus CO₃^2‐ and the ethanol mole fraction in WEBS. The vaterite phase would transform to either aragonite or calcite decided by the surplus CO₃^2‐ ions or Ca²⁺ ions, respectively. SEM observation shows that the polymorph evolution also induced the morphology change. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Template‐directed growth and characterization of flowerlike porous carbonated hydroxyapatite spheres

Flowerlike porous carbonated hydroxyapatite (CHAp) spheres were synthesized by the template‐directed homogeneous precipitation method. The carbonate content of synthetic CHAp determined by carbon elemental analysis was about 1.50 wt/wt. FT‐IR and XRD were employed to analyze the chemical composition of porous CHAp and SEM was used to observe crystal morphology. We studied the effect of the concentration [Ca] and [P] on ingredient and structure, the effect of urea on hierarchical structure, and the effect of the template on morphology. The results suggested that the lower concentration of [Ca] and [P] was advantageous to purity and monodispersity, that the resultant would be prone to a fancy assembly of big flakes into disks at the lower concentration of urea, and that the aperture could be regulated from micrometer size to nanometer size via altering the concentration of the template. This porous material with the hierarchical structure exhibits especial surface characteristics and has a high surface area, showing potential applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Microstructural characterization of CPPD and hydroxyapatite crystal depositions on human menisci

Meniscus is a fibrocartilaginous tissue composed mainly of water and a dense elaborate collagen network with a predominantly circumferential alignment. Crystal formation and accumulation on meniscal tissue is frequently observed especially in elderly. In this study, we used X‐ray diffraction (XRD), FTIR and FT‐Raman for the structural identification of the depositions and Optical microscopy, Scanning Electron microscopy (SEM/EDX) and Atomic Force microscopy (AFM), in order to investigate the structural relationship between the crystal deposits and the collagen fibers of human meniscal tissues. We are reporting on the formation of intercalary “colonies” of Calcium Pyrophosphate Dihydrate (CPPD) crystals with two distinct morphologies corresponding to the monoclinic and the triclinic phase, as well as the formation of micro‐aggregations composed of nano‐crystalline HAP aggregations which are developed along the longitudinal axis of collagen fibers without extensively disturbing the collagens arrangement.     

Characterization of pure and doped potassium hydrogen tartrate single crystals grown in silica gel

Growth of pure‐, sodium‐ and lithium‐ doped potassium hydrogen tartrate single crystals by gel technique is reported. Growth conditions conducive for the growth of single crystals are worked out. The crystals are characterized by using powder XRD, SEM, FTIR, AES, EDAX, CH analysis and thermoanalytical techniques. The stoichiometric composition for the grown crystals are established as KHC₄H₄O₆.H₂O, (K)_0.98(Na)_0.02.H₂O and (K)_0.94(Li)_0.06HC₄H₄O₆.H₂O. Doping of sodium and lithium in the pure potassium hydrogen tartrate single crystals is found to influence the size, perfection, morphology, crystal structure and the thermal stability of crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and characterizations of nano sized MgO and its nano composite with poly(vinyl alcohol)

Magnesium oxide (MgO) nano particle was synthesized by ultrasound assisted one pot method and thus synthesized nano MgO was mixed with poly(vinyl alcohol) (PVA) to prepare the polymer nano composite. The influence of the nano sized MgO on the structural modification of PVA was evaluated. The particle size and morphology of MgO was confirmed by High Resolution Transmission Electron Microscopy (HRTEM). The properties of PVA/MgO nano composite materials were characterized by Fourier Transform Infrared analysis (FTIR), Thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) like analytical tools.     

Investigation of structural,electronic and optical properties of pure and Ag‐doped TiO2 nanofibers fabricated by electrospinning

Pure and 1, 2, and 3 wt% Ag doped TiO₂ nanofibers were prepared by electrospinning method at different applied voltages and heights at a constant flow rate of 2 mL/h. Characterization of the prepared samples was performed by x‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microcopy (AFM),four point probe method (FPPM), the differential scanning calorimetry/the thermal gravimetric analysis (DSC/TGA), ultraviolet/visible spectrometry (UV/VIS), and energy dispersive X‐ray spectrometer (EDX). It was found that the thermally untreated pure TiO₂ nanofibers and thermally treated (at 500 °C) samples have the crystalline phase of anatase (A), and mixed anatase and rutile (A+R) phases, respectively. It was also observed that the content of the silver does not affect the crystal structure, but plays strengthening role in the rutile structure. SEM micrographs showed that all fabricated nanofiber samples have uniform morphologies, and AFM measurements indicated that the nanofibers were formed in three‐dimensional coils. The band gap values of the nanofiber samples obtained from UV/VIS measurements revealed that band gap values of the nanofiber samples decrease while the diameter of the nanofiber increases.     

SiCN薄膜在Si衬底上的沉积

本文采用微波等离子体化学气相沉积(MPCVD)系统,在单晶Si衬底上制备出了SiCN薄膜.所采用的源气体为高纯CH4和N2,而Si源来自于Si衬底、SiH4和Si棒.用场发射扫描电镜(SEM)、X射线光电子能谱(XPS)和X射线衍射谱(XRD)对样品进行了表征与分析.结果表明,外加Si源、高的衬底温度、高流量N2有助于提高样品的成膜质量.所得到SiCN样品是新型的六方结构三元化合物.     

Aspergillums Niger assisted crystal growth of calcium tartrate: an alternative method to grow crystals

A novel method of growing calcium tartrate single crystals was developed in which the crystals were hanging freely in solution assisted by fine filaments of fungi (Aspergillums niger). Spores of A. niger were inoculated and allowed to grow in the supernatant solution of calcium chloride and tartaric acid (1:1) on the silica hydro‐gel impregnated with orthophosphoric acid. Transparent, prismatic, calcium tartrate crystals were grown hanging in the filamentous network of the fungi after 10 days in the supernatant solution. This network of the mycelium facilitated and mimicked the gel. The grown crystals were identified as calcium tartrate trihydrate and characterized by powder XRD, FTIR and TGA. This technique provides an alternate and a novel technique to grow crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Spectroscopy of Charge Transfer Complexes of Aniline Blue

Charge transfer (CT) complexes of aniline blue (AB) were prepared with standard organic acceptors such as TCNQ, TCNE, DDQ, and chloranil and studied with UV-VIS-NIR spectra showing σ→π* and π→π* transitions along with free-carrier absorption due to scattering of light particles which has been found involving phonon–photon, electron–photon, and electron–electron scattering. Infrared spectra contain half power beta density due to hopping conduction and an asymmetric band corresponding to A(k) = A₀k exp(?bk) as absorption associated with diffraction of IR light from the crystalline particles.     

Preparation and characterization of electrodeposited indium selenide thin films

Indium Selenide (InSe) thin films were deposited from a mixture of Indium chloride and selenium dioxide in aqueous solution by electrodeposition technique on Indium Tin oxide coated glass substrates. The effects of the parameters during deposition such as current density, deposition potential versus saturated calomel electrode, pH value and concentration of source material were studied. X‐ray diffraction studies were carried out on the films to analyze the microstructure using an x‐ray diffractometer and were examined by RAMAN spectroscopy. The Raman peak position did not change much with chemical concentrations. Raman scattering due to the (LO) phonon was observed at 211 cm^–1. Optical absorption studies were performed with a double beam ultra violet‐visible –NIR spectrophotometer in the wavelength 300–1100 nm. The surface morphology of the layer was examined using a scanning electron micrograph. The composition of the films was studied using an Energy Dispersive Analysis by X‐Rays (EDAX).     

Spherulitic crystallization of β‐In2Te3 by physical vapour deposition

Different morphologies of indium telluride (In₂Te₃) including novel spherulites were crystallized using the physical vapour deposition (PVD) method, by varying the difference in the growth and source zone temperature (ΔT) of a dual zone horizontal furnace assembled indigenously. Whiskers and kinked needles of In₂Te₃were grown at ΔT = 250 K and 300 K respectively, maintaining the growth zone at 500 °C. At high supersaturation (Δ T = 400 K), spherulitic crystals were obtained. The stoichiometric composition of these crystals has been confirmed using energy dispersive analysis by x‐rays (EDAX). The structure of β‐In₂Te₃ spherulitic crystals is identified as zinc blende with lattice parameter a = 6.159 Å, from x‐ray diffraction (XRD) studies. The scanning electron microscope (SEM) images revealed the radial structure of the grown spherulites. The growth mechanism for the spherulitic crystallization of β‐In₂Te₃ crystals has been discussed based on the theoretical models. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Characterisation and mesomorphic behaviour of liquid crystals with dispersed PdCl2 nanoparticles

The synthesis and characterisation are carried on liquid crystalline (LC) p-dodecyloxy benzoic acid (12OBA) with 1 and 2 wt% for PdCl₂ nanoparticles dispersion. Further, characterizations are carried out by different spectroscopic techniques like X-ray diffraction spectrometric studies, scanning electron microscopy, Fourier transform infrared and differential scanning calorimetry (DSC). Textural determinations of the synthesised compounds are recorded by using polarising optical microscope (POM) attached with a hot stage and camera. The results show that the dispersion of PdCl₂ nanoparticles in 12OBA exhibits Nematic phases as same as the pure 12OBA with reduced clearing temperature as expected. Further, the nematic thermal ranges are quenched and the smectic C thermal range has been increased while performing both DSC and POM with the dispersion of 1 wt% PdCl₂ nanoparticles. Size dependence on bonding nature with LC compounds is established.     

Synthesis from zinc oxalate,growth mechanism and optical properties of ZnO nano/micro structures

We report the synthesis of various morphological micro to nano structured zinc oxide crystals via simple precipitation technique. The growth mechanisms of the zinc oxide nanostructures such as snowflake, rose, platelets, porous pyramid and rectangular shapes were studied in detail under various growth conditions. The precursor powders were prepared using several zinc counter ions such as chloride, nitrate and sulphate along with oxalic acid as a precipitating agent. The precursors were decomposed by heating in air resulting in the formation of different shapes of zinc oxide crystals. Variations in ZnO nanostructural shapes were possibly due to the counter ion effect. Sulphate counter ion led to unusual rose‐shape morphology. Strong ultrasonic treatment on ZnO rose shows that it was formed by irregular arrangement of micro to nano size hexagonal zinc oxide platelets. The X‐ray diffraction studies confirmed the wurzite structure of all zinc oxide samples synthesized using different zinc counter ions. Functional groups of the zinc oxalate precursor and zinc oxide were identified using micro Raman studies. The blue light emission spectra of the various morphologies were recorded using luminescence spectrometer. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth of YCOB single crystals by flux technique and their characterization

Nonlinear optical single crystals of YCOB with good optical quality were grown by the flux technique for the first time. Polycrystalline YCOB samples were synthesized by solid state reaction method. The thermal analysis of the sample was performed with lithium carbonate flux in different weight proportions and the growth temperature was optimised. Single crystals of YCOB with dimensions 3 × 3 × 5 mm³ were obtained by the method of ‘slow‐cooling’. The grown crystals were characterized by XRD, UV‐VIS‐NIR, EDAX, FTIR and etching studies. The powder XRD pattern revealed the formation of YCOB compound. The lattice parameters were identified through single crystal XRD studies. The UV‐VIS‐NIR results showed that the crystal has a sharp cutoff at 220 nm and is nearly 55% transparent over a wide wavelength range enabling applications in the UV region. The EDAX measurement revealed the ‘flux‐free’ crystal formation. The presence of the functional groups belonging to the YCOB crystals was identified by the FTIR results. ‘Hillock‐like’ patterns are observed in the etching studies. The primary emphasis in this study is laid to describe ‘flux technique’ as an alternative method to grow YCOB crystals. The results are presented and discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Evaluation and investigation on the effect of ionic liquid onto PMMA-PVC gel polymer blend electrolytes

1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl imide), BmImTFSI based poly(methyl methacrylate)-poly (vinyl chloride), PMMA-PVC gel polymer electrolytes were prepared by solution casting technique. These ionic liquid-based gel polymer electrolytes exhibit Arrhenius type temperature dependence of ionic conductivity. The highest ionic conductivity of (8.08 ± 0.01) × 10^− 4 Scm⁻¹ was achieved at 80 °C upon addition of 60 wt.% of BmImTFSI. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies revealed the amorphous nature and morphology of these polymer electrolytes, respectively. The lower coherence length of the peak inferred the higher amorphous degree in these polymer matrices. Decreases in T_g and T_m indicate the flexibility of polymer backbone. The amorphous behavior of these ionic liquid-based gel polymer electrolytes are also enhanced as shown in differential scanning calorimetry (DSC) analysis. On the contrary, thermogravimetric analysis (TGA) divulges that the thermal stability of polymer electrolytes has been improved upon impregnation of BmImTFSI.