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ABSTRACT: Nogo-66 and NgR are important receptors inhibiting neuronal regeneration and therefore are targets for treating CNS injury. Antagonists of this receptor including blocking antibodies are potential therapeutic agents for CNS axonal injuries such as spinal cord and brain trauma. A new antibody (IgG) releasing system has been developed by covalently attaching IgG to the biodegradable hyaluronic acid (HA) hydrogel via the hydrolytically unstable hydrazone linkage, aiming to deliver the antibody of CNS regeneration inhibitors to the injured brain. In this paper we describe the synthesis, physico-chemical characteristics and test results of biological activity of antibody released from hyluronic acid hydrogel. To form the conjugates the antibody is attached to the polymer backbone using a condensation reaction between aldehyde group of the antibody and hydrazide group of the HA hydrogel. Furthermore, pH sensitive linkage-hydrozone has been formed between hydrogel and antibody. The amount of conjugated antibodies can reach 135 microg antibody/mg hydrogel in the dry state. At low pH, the antibodies released quite fast. However, the antibodies released much slower in neutral and alkaline environment. The bioactivity of antibody released from hydrogel was retained as demonstrated by indirect immunofluorescence technique.
Journal of Controlled Release 02/2005; 102(1):13-22. · 5.73 Impact Factor
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ABSTRACT: Al13-pillared anatase TiO2 is used as a cathode of a lithium battery for the first time. First, a layered titanium dioxide with cationic surfactant ions of cetyltrimethylammonium (CTA+) in the interlayers is synthesized by self-assembly. Then, pillared TiO2 is obtained by exchange of polyoxo cations of aluminium, [Al13O4(OH)24(H2O)12]7+, with CTA+ and subsequent calcination at 300 °C for 1 h in the air. Powder x-ray diffraction (XRD), transmission electron microscopy (TEM) and surface area (BET) methods are used to characterize the layered and pillared forms of titanium dioxide. A lithium battery with the Al13-pillared TiO2 as the cathode and Li metal foil as the anode is studied within the 1–2.2 V voltage range. The specific capacity of the closed button cell (size 2025) that is delivered on the initial discharge reached 191.4 mA h g−1 at the rate of 25 mA g−1. The cell shows good cycling performance over 50 cycles.
Nanotechnology 09/2004; 15(11):1535. · 3.98 Impact Factor
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ABSTRACT: Percolation structures are formed during the amorphous-to-crystalline phase transition induced by ion beam irradiation in Ni-Mo alloy films. It is found that the percolating networks emerged at the critical point of the transition and they were well fitted for the percolation scales. The direct observations, in this study, provide the evidences of the percolation behaviours upon such a phase transition in thin solid films.
Journal of Physics C Solid State Physics 11/2000; 21(3):L51.
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ABSTRACT: An icosahedral phase has been observed for the first time in the equilibrium immiscible Fe-Cu system. The new metastable phase was formed by directed xenon ion mixing of Fe/Cu multilayers at room temperature and without any amorphous-to-quasi-crystalline phase transition. The atomic concentration of this phase was determined by in situ energy-dispersive spectroscopy (EDS) to be around Fe60Cu40.
Journal of Physics F Metal Physics 11/2000; 18(5):L69.
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ABSTRACT: The structure and crystallographic orientation of mineral phase in the oblique prismatic layer of Mytilus edulis shell were studied by SEM, XRD and TEM with selected area electron diffraction (SAED). A crystallographic orientation regulation, i.e. the adjacent 1–5 calcite prisms with the same three-dimensional orientation in the oblique prismatic layer, was found for the first time. It is observed that the calcite prisms in the oblique prismatic layer were grown with their (104) parallel to the shell surface.
Journal of Materials Science 01/2000; 35(13):3337-3340. · 2.02 Impact Factor
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Journal of Materials Science Letters 09/1999; 18(19):1547-1549.
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ABSTRACT: The influence of surface energies on line resolution in screen
printing was studied in this paper. Ink wettability on surfaces is
decreased by decreasing the surface energies of substrates-the reduction
in wettability improves the line resolution. For such high
surface-energy substrates as ceramics, the effective means to improve
the line resolution is to use high thixotropic inks. On the other hand,
for low surface energy polymer substrates, the line resolution can be
heightened by increasing the surface energies of inks. If the critical
surface tension of a substrate is lower than the surface energy of inks,
good line resolution can be achieved even though low viscosity inks were
used. The use of low viscosity inks has quite a lot of advantages
IEEE Transactions on Components Packaging and Manufacturing Technology Part B 06/1996;
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ABSTRACT: The deformation, fracture and toughening mechanisms of nacre from a kind of fresh-water bivalve mollusc (Cristaria plicata) were studied by SEM, TEM and microindentation tests. Experimental results revealed a strong anisotropy of the damage behaviour reflecting the microstructural character of nacre. The fractured surface parallel to the cross-sectional surface of nacre was much more tortuous than that parallel to the platelet surface. The crack line on the cross-sectional surface was step-like, while that on the platelet surface was polygonal. Sliding of aragonite layer combined with the plastic deformation of organic matrix is the main plastic deformation mechanism of nacre. Three main toughening mechanisms have been found acting in concert: crack deflection, fibre pull-out and organic matrix bridging.
Journal of Materials Science 04/1995; 30(9):2299-2304. · 2.02 Impact Factor
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ABSTRACT: A three-layer structure, including a columnar layer (CL), a buffer layer, and unaffected intact enamel, was successively formed from the outer to the inner part of artificial enamel lesions (AEL) by topical applications of a high-concentration acidic sodium fluoride solution (10,000 ppm, pH 5.6) in vitro. The AEL was produced in bovine enamel that was decalcified for 5 days in a lactic acid gel system. The morphological observations by using scanning electron microscopy showed that the CL was made of columnar deposits of small globules about 0.5 microns in diameter. It was observed for the first time that small globules filled the demineralized interprismatic regions in the buffer layer. The unaffected intact enamel was protected from further demineralization under the acidic condition. Structure and composition of the CL were investigated by using X-ray diffraction and X-ray photoelectron spectroscopy. In the CL the atomic ratio was Ca:P = 12.6 and Ca:F = 0.75, and the small globules were mainly a mixture of polycrystalline calcium fluoride and hydroxyapatite. For comparison, the sound enamel and the AEL attained by applications of 0 and 100 ppm acidic sodium fluoride solutions (pH 5.6) were also investigated. The formation mechanism of the three-layer structure and the related cariostatic effects are discussed.
Caries Research 02/1995; 29(2):122-9. · 2.33 Impact Factor
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Journal of Materials Science Letters 12/1994; 14(7):490-492.
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Journal of Materials Science Letters 12/1993; 13(14):1042-1044.
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ABSTRACT: Transmission electron microscope studies of the cellular nucleation sites of a biomineralized calcium carbonate(aragonite) in the lamellar nacreous layer of the bivalvia Cristaria plicata (Leach) shell showed that the low density calcium particles were confined within some large vesicles of the bivalve mantle cells on which the crystalline aragonite phases were deposited. These vesicles served as the nucleation sites for the growth of the crystals. The crystalline phases at the first few lamellae were mostly imperfect while the whole nacreous layer acquitted itself into a highly oriented biomineralized aragonite. The structure of the vesicles is addressed in detail.
Biochemical and Biophysical Research Communications 05/1991; 176(2):654-9. · 2.48 Impact Factor
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ABSTRACT: Experimental observations of fractal growth at dendrite tips during crystalline-to-amorphous phase transition in an ion-irradiated
Mo65Ni35 thin film are reported. It was found that the observed anisotropic fractal patterns were of a DLA type but not exactly self-similar.
The possible mechanism of this exception to the ordinary parabolic tip growth of the dendrites is discussed.
Il Nuovo Cimento D 08/1988; 10(9):1117-1123.
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ABSTRACT: An experimental study of the growth of fractal patterns during ion beam‐solid interaction in the Ni‐Zr alloy system is reported. The observed fractal patterns in the alloy films feature both isotropic and anisotropic characters depending on their growth surroundings. The fractal dimension of the isotropic fractal patterns is determined to be 1.4±0.1. The possible growth mechanism of the observed patterns is discussed.
Journal of Applied Physics 05/1988; · 2.17 Impact Factor
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ABSTRACT: Strong evidence that amorphization was achieved by ion-beam mixing in a Fe-Cu system that has a large positive heat of formation (+19kJ/mole) is reported. The composition of the films, Fe70Cu30, was chosen according to those of the localized amorphous phase determined by energy dispersive spectroscopy. The phase identification by transmission electron microscopy, as well as the results from Rutherford backscattering, indicated that the formation of an amorphous phase and the mixing efficiency by ion-beam mixing depended greatly on the alloy composition. Raman spectra were obtained from the metal-metal thin amorphous films in this study and the related results are discussed.
Applied Physics A 01/1987; 44(3):269-272. · 1.63 Impact Factor
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ABSTRACT: Nogo-66 and NgR are important receptors inhibiting neuronal regeneration and therefore are targets for treating CNS injury. Antagonists of this receptor including blocking antibodies are potential therapeutic agents for CNS axonal injuries such as spinal cord and brain trauma. A new antibody (IgG) releasing system has been developed by covalently attaching IgG to the biodegradable hyaluronic acid (HA) hydrogel via the hydrolytically unstable hydrazone linkage, aiming to deliver the antibody of CNS regeneration inhibitors to the injured brain. In this paper we describe the synthesis, physico-chemical characteristics and test results of biological activity of antibody released from hyluronic acid hydrogel. To form the conjugates the antibody is attached to the polymer backbone using a condensation reaction between aldehyde group of the antibody and hydrazide group of the HA hydrogel. Furthermore, pH sensitive linkage-hydrozone has been formed between hydrogel and antibody. The amount of conjugated antibodies can reach 135 μg antibody/mg hydrogel in the dry state. At low pH, the antibodies released quite fast. However, the antibodies released much slower in neutral and alkaline environment. The bioactivity of antibody released from hydrogel was retained as demonstrated by indirect immunofluorescence technique.
Journal of Controlled Release.
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ABSTRACT: Microstructures of the early external callus after diaphyseal fractures of human long bone were investigated by using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. It was found that the main structural framework of the human early callus consists of disordered, mineralized collagen fibrils with a small fraction of regions of ordered collagen fibrils. X-ray diffraction analyses show that hydroxyapatite containing some carbonate impurity has been the dominant crystalline phase in the human early callus. In addition, a small amount of brushite phase was detected. Selected area diffraction analyses indicated that hydroxyapatite microcrystals were embedded in microfibrils with a diameter of 4.5 nm and well-banded fibrils, whereas brushite particles of 15-20 nm in an irregular shape were located in the noncollagenous organic matter around the nonmineralized, ordered collagen fibrils. The spatial distribution of the brushite particles in the human early callus was for the first time determined. The brushite particles probably serve as the reservoir of calcium and phosphate ions for subsequent mineralized periods rather than the precursor of hydroxyapatite.
Journal of Structural Biology 114(2):115-22. · 3.41 Impact Factor
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ABSTRACT: Brain tissue engineering in the postinjury brain represents a promising option for cellular replacement and rescue, providing a cell scaffold for either transplanted or resident cells. In this article, a hyaluronic acid (HA)-poly-D-lysine (PDL) copolymer hydrogel with an open porous structure and viscoelastic properties similar to neural tissue has been developed for brain tissue engineering. The chemicophysical properties of the hydrogel with HA:PDL ratios of 10:1, 5:1, and 4:1 were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectrometry. Neural cells cultured in the hydrogel were studied by phase-contrast microscope and SEM. The incorporation of PDL peptides into the HA-PDL hydrogel allowed for the modulation of neuronal cell adhesion and neural network formation. Macrophages and multinucleated foreign body giant cells found at the site of implantation of the hydrogel in the rat brain within the first weeks postimplantation decreased in numbers after 6 weeks, consistent with the host response to inert implants in numerous tissues. Of importance was the infiltration of the hydrogel by glial fibrillary acidic protein-positive cells-reactive astrocytes-by immunohistochemistry and the contiguity between the hydrogel and the surrounding tissue demonstrated by SEM. These findings indicated the compatibility of this hydrogel with brain tissue. Collectively, the results demonstrate the promise of an HA-PDL hydrogel as a scaffold material for the repair of defects in the brain.
Tissue Engineering 11(3-4):513-25. · 4.02 Impact Factor
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ABSTRACT: The SnO2 nanoparticles coated on SiO2 microspheres were prepared with the hydrous tin chloride, NH3·H2O and the slurry of amorphous silica microspheres in an aqueous medium. X-ray powder diffraction (XRD), Fourier transformed infrared (FTIR) spectra, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), and UV–vis spectrophotometer were used to characterize the SiO2–SnO2 core–shell structured particles. The XRD of the SnO2 nanoparticles coated on SiO2 microspheres yields diffraction peaks corresponding to the cassiterite SnO2 phase. The FE-SEM and TEM images show that the SnO2 nanoparticles (diameter 3.9 nm) coated SiO2 surface as thin layers or nanoclusters, depending on the reactant concentration. UV–vis spectrum shows an absorption edge at around 315 nm, which is markedly blue-shifted compared to that of bulk SnO2 (350 nm).
Materials Chemistry and Physics. 107:248-253.
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ABSTRACT: The effect of ionic concentration and pH on matrix-regulated crystallization may be important in biomineralization processes and biomimetic synthesis of materials. This effect in the system of calcium phosphate solution under stearic acid monolayers was investigated. In experiments, the solution conditions ranged in concentration of Ca ion of 0.1–20mM and in pH of 5.3–7.0. It was found that at the initial stage of the controlled crystallization, the (0001)-oriented hydroxyapatite (HAp) precipitations under the acidic monolayers always occur. At solution conditions near the solubility isotherms of octacalcium phosphate (OCP) and dicalcium phosphate dihydrate (DCPD) in the solubility phase diagram, precipitations of OCP and DCPD phases can form together with HAp precipitation, respectively. Orientations of DCPD or OCP phase precipitations were irregular.
Journal of Crystal Growth 169(3):557-562. · 1.73 Impact Factor
