Structure and properties of bone-like-nanohydroxyapatite/gelatin/polyvinyl alcohol composites

Bone-like nanohydroxyapatite powders (b-nanoHA) were synthesized in simulated body fluid (SBF). The b-nanoHA, gelatin (Gel) and Polyvinyl Alcohol (PVA) were used to prepare bone-like composites (b-nanoHA/ Gel/PVA) at room temperature. Characterizations of b-nanoHA powders and b-nanoHA/Gel/PVA composites were investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), High-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Bending strength and compressive strength of the composite were tested. It was found that microstructure of the b-nanoHA powders was whisker shape and its crystalline degree was low similar to natural bone, bending strength and compressive strength of the b-nanoHA/Gel/PVA composite depended on the mixing ratio of HA, Gel and PVA, and also PVA could induce the network formation in the b-nanoHA/Gel/ PVA composite.

Silicon-phthalocyanine bonding with SiO_2 matrix and its strong optical limiting effects

Silicon-phthalocyanine (SiPc) is chemically bonded to 3-aminopropltriethoxysilane (NH2(CH2)3Si(OC2H5)3, KH550) by the nucleophilic substituted reaction between the active chlorine of silicon dichlorine phthalocyanine (SiPcCI2) and amino-group of KH550. The reacted product is hybridized with 3-glycidoxypropltrimethoxysilane (CH2OCHCH2O(CH2)3Si(OCH3)3, KH560) with sol-gel processing to form sol-gel inorganic material with good physical-chemical and optical properties. Due to tethering SiPc to the network, the aggregation of SiPc is effectively prevented in sol-gel derived matrix, and the doping concentration of SiPc in the form of monomer in the matrix is greatly enhanced. The cross-linkage of SiPcCI2 and KH550 is estimated and confirmed with FT-IR spectra. The optical limiting effects (OLE) of the gel with different content of SiPc are investigated with a frequency double Q-switched Nd3+:YAG laser of 8 nsec. pulse.

PROTON NUCLEAR MAGNETIC RESONANCE AND ELECTRON PARAMAGNETIC RESONANCE INVESTIGATION OF α-α CROSS-LINKED Fe-Co HYBRID HEMOGLOBINS

The following asymmetric α1 99 Lys-α2 99 Lys cross-linked Fe(Ⅱ)-Co(Ⅱ) hybrid hemoglobins (Hbs) were first prepared from derivatives of hemoglobin C (β6 Glu-Lys) and human normal HbA: [α(Co)β(Fe)]A[α(Co)β(Co)]cXL, [α(Fe)β(Co)]A[α(Co)β(Co)]cXL, etc.Their 500 MHz 1H NMR and EPR spectra were measured in order to study the change in their tertiary and quaternary structure under atmosphere of deozy, oxy and carbon monoxide (with or without IHP). From the change of T and R marks in 1H NMR hydrogen bonding region, it is proved that oxygen molecules are first bonded to α(Fe) subunits rather than to β(Fe). The experimental phenomena provided further evidence that intermediate states of ligation are present in addition to T and R state during process of binding of oxygen to Hb. IHP facilitates transformation of T state to R state. The same conclusion can also be drawn from the results of EPR spectra at 77 K.

Fabrication and mechanical properties of single-wall carbon nanotubes and hyperbranched diazonium salt multilayers

Acidized single-wall carbon nanotubes(SWNTs)were fabricated into multilayers with a hyperbranched azobenzene-containing polymeric diazonium salt(PDAS)using the layer-by-layer adsorption technique.The fabrication process,multilayer thickness variation,multilayer surface morphology and the interaction between SWNTs and PDAS were monitored byUV-Vis absorption spectroscopy,optical ellipsometry,Atomic Force Microscopy,Scanning Electron Microscopy and Raman spectroscopy.Moreover,the nanomechanical properties of the multilayer films were measured by nanoindentation.All results show that SWNTs and PDAS can be fabricated intomultilayers based on the cooperation of electrostatic absorption and chemical cross-linkage between SWNTs and PDAS.Further,this cooperation endows the SWNT/PDAS multilayer films with outstanding nanomechanical properties.The hardness and modulus are about 2.0GPa and 10.0GPa,respectively.Finally,the SWNT/PDAS multilayer film can be peeled off to be a free-standing film.