Controlled Crystallization of Tooth-Like Hydroxyapatite under Gelatin Monolayer

2007 ◽  
Vol 330-332 ◽  
pp. 663-666
Author(s):  
Kun Tian ◽  
Dong Hua Guan ◽  
Ping Wu ◽  
Chun Peng Huang ◽  
Lin Niu ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Molar Ratio ◽  
Dentinal Tubule ◽  
X Ray Diffraction ◽  
X Ray ◽  
Whole Process ◽  
Crosslinking Process ◽  
Recognition Theory ◽  
Parallel Direction

Based on the molecular recognition theory, an organic molecules model was designed to induce the hydroxyapatite crystallization, to build a tooth-like calcium phosphate/hydroxyapatite under a controllable way in vitro. The cross-linking of collagen on the dentin surface and gelatin was optimized by varying the molar ratio of N,N-(3-dimethylaminopropyl)- N'-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) at a constant EDC concentration. CaCl2 and Na3PO4-12H2O solutions were added after the crosslinking process. The whole process requires repeating the crosslinking and mineralization process for five times. The obtained composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) as well as energy dispersive X-ray photoelectron spectroscopy (XPS). The results showed that the dentinal tubule were blocked by neonatal hydroxyapatite layer which has a continuous structure of columns crystal with size of 10-40nm. Furthermore, there was column crystal with parallel direction inside, similar to the crystal array in the top of enamel rod. This study showed that the specific organic molecule model can be used as a potential effective crystal growth modifier.

Biomimetic Synthesis of Tooth-Like Hydroxyapatite under Organic Polymer Monolayer

2009 ◽  
Vol 610-613 ◽  
pp. 1054-1058
Author(s):  
Kun Tian ◽  
Hui Min Shuai ◽  
Xiao Min Yang
Keyword(s):  
Biomimetic Synthesis ◽  
Organic Polymer ◽  
Molar Ratio ◽  
Dentinal Tubule ◽  
Ftir Analysis ◽  
X Ray ◽  
Dentin Surface ◽  
Crosslinking Process ◽  
Protein Monolayer

Based on the basic theory of molecular recognition , we design a organic molecules model to induce the crystallization of hydroxyapatite to synthesized tooth-like calcium phosphate/hydroxyapatite under a controllable way in vitro. The cross-linking of collagen on the dentin surface and extraneous collagen was optimized by varying the molar ratio of N,N-(3-dimethylaminopropyl)- N'-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) at a constant EDC concentration. CaCl2 and Na3PO4-12H2O solutions were added after the crosslinking process. X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis of organic protein monolayer for samples. The obtained composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) as well as energy dispersive X-ray (EDX). XPS and FTIR analysis showed the surface organic compositions in experimental group is higher than that of normal dentin and decalcified dentin surface. The results showed that the dentinal tubule were blocked by neonatal hydroxyapatite layer which has a continuous structure of columns crystal with size of 10-40nm. Furthermore, there were column crystal with parallel direction inside, similar to the crystal array in the top of enamel rod. This study showed that the specific organic molecule model can be used as a potential effective crystal growth modifier.

scholarly journals Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 346
Author(s):  
Sonam Goyal ◽  
Maizatul Shima Shaharun ◽  
Ganaga Suriya Jayabal ◽  
Chong Fai Kait ◽  
Bawadi Abdullah ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalyst Support ◽  
Oxidation Potential ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Optimum Parameters ◽  
Reduction Of Co2 ◽  
Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

Silk Protein Assisted Ex Vivo Remineralization of Enamel-Like Microstructure

2011 ◽  
Vol 66-68 ◽  
pp. 1682-1687
Author(s):  
Kun Tian ◽  
Min Peng ◽  
Ping Wu ◽  
Chu Hang Liao ◽  
Fa Yin Huang
Keyword(s):  
Ex Vivo ◽  
Three Dimensional ◽  
Silk Protein ◽  
Molar Ratio ◽  
Dentinal Tubule ◽  
Dental Tissue ◽  
Parallel Direction ◽  
Protein Monolayer ◽  
Dental Tissue Engineering

Based on the basic theory of molecular recognition, we designed an organic molecules model that spontaneously form three-dimensional fibrillar scaffolds to induce the crystallization of hydroxyapatite to synthesized enamel-like calcium phosphate/hydroxyapatite under a controllable way in vitro. Cross-linking of collagen on the dentin surface and silk fibroin with N,N-(3-dimethylaminopropyl)-N'-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) was optimized by varying the NHS/EDC molar ratio at constant EDC concentration. CaCl2 and Na3PO4-12H2O solution was added with Ca: P odd as 1.67:1 after conjugated. The results showed that the dentinal tubule were blocked by neonatal hydroxyapatite layer which has a continuous structure of columns crystal with size of 10-40nm. Furthermore, there were column crystal with parallel direction inside, similar to the crystal array in the top of enamel rod. The results suggest that silk protein monolayer may be useful in the modulation of mineral behavior during in situ dental tissue engineering.

Synthesis, Characterization and Photocatalytic Activity of Nb-Doped TiO2 Nanoparticles

2012 ◽  
Vol 455-456 ◽  
pp. 110-114 ◽  
Author(s):  
Xuan Dong Li ◽  
Xi Jiang Han ◽  
Wen Ying Wang ◽  
Xiao Hong Liu ◽  
Yan Wang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Doped Tio2 ◽  
X Ray ◽  
Vis Spectroscopy

Nb-doped TiO2 powders with different concentrations of Nb have been synthesized by a sol-gel method and characterized by a series of technologies including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. The photocatalytic activity of Nb-doped TiO2 is evaluated by degradation efficiency of methyl orange in aqueous solution. The results indicate that the photocatalytic activity of Nb-doped TiO2 synthesized with a Nb/Ti molar ratio of 5% is higher than that of TiO2 under the visible light.

Stoichiometric Controlling of Spark Plasma Sintered Boron-Carbon Ceramics

2009 ◽  
Vol 66 ◽  
pp. 25-28 ◽  
Author(s):  
Song Zhang ◽  
Chuan Bin Wang ◽  
Qiang Shen ◽  
Lian Meng Zhang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Measurement Data ◽  
Atomic Ratio ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Carbon Ceramic ◽  
Boron Carbon

A group of boron-carbon ceramic material was in-situ synthesized and densified simultaneously via Spark Plasma Sintering (SPS) technique from carbon and boron element powders with different molar ratio. The phase structures of samples with different B/C molar ratio were characterized by X-ray Diffraction (XRD). The B/C atomic ratio of the sintered materials was calculated from X-ray photoelectron spectroscopy (XPS) measurement data. Meanwhile, the chemical analysis (CA) method had also been taken to verify the B/C atomic ratio. Finally, the experience equation had been obtained to control the B/C atomic ratio of sintered samples.

scholarly journals CO2 Methanation of Biogas over 20 wt% Ni-Mg-Al Catalyst: on the Effect of N2, CH4, and O2 on CO2 Conversion Rate

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1201
Author(s):  
Danbee Han ◽  
Yunji Kim ◽  
Hyunseung Byun ◽  
Wonjun Cho ◽  
Youngsoon Baek
Keyword(s):  
Reaction Temperature ◽  
Photoelectron Spectroscopy ◽  
Conversion Rate ◽  
Space Velocity ◽  
Molar Ratio ◽  
Co2 Conversion ◽  
X Ray Diffraction ◽  
Co2 Methanation ◽  
X Ray ◽  
Ch4 Production

Biogas contains more than 40% CO2 that can be removed to produce high quality CH4. Recently, CH4 production from CO2 methanation has been reported in several studies. In this study, CO2 methanation of biogas was performed over a 20 wt% Ni-Mg-Al catalyst, and the effects of CO2 conversion rate and CH4 selectivity were investigated as a function of CH4, O2, H2O, and N2 compositions of the biogas. At a gas hourly space velocity (GHSV) of 30,000 h−1, the CO2 conversion rate was ~79.3% with a CH4 selectivity of 95%. In addition, the effects of the reaction temperature (200–450 °C), GHSV (21,000–50,000 h−1), and H2/CO2 molar ratio (3–5) on the CO2 conversion rate and CH4 selectivity over the 20 wt% Ni-Mg-Al catalyst were evaluated. The characteristics of the catalyst were analyzed using Brunauer–Emmett–Teller surface area analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The catalyst was stable for approximately 200 h at a GHSV of 30,000 h−1 and a reaction temperature of 350 °C. CO2 conversion and CH4 selectivity were maintained at 75% and 93%, respectively, and the catalyst was therefore concluded to exhibit stable activity.

scholarly journals Hydrothermal synthesis of monocopper sulfide for hydrogen peroxide-assisted photodegradation of paraquat

2020 ◽  
Vol 26 (1) ◽  
Author(s):  
Rattabal Khunphonoi ◽  
Kitirote Wantala ◽  
Nurak Grisdanurak
Keyword(s):  
Photoelectron Spectroscopy ◽  
Reaction Rate ◽  
Ageing Time ◽  
Reaction Rate Constant ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Energy Band Gap ◽  
X Ray ◽  
Synthesis Parameters ◽  
Transmission Electron

Copper sulfide was prepared by a hydrothermal method at 130°C. The copper to sulfur molar ratio (6-10) and ageing time (24-72 h) were their synthesis parameters. The obtained materials were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscope (TEM), UV-DR spectroscopy and X-ray photoelectron spectroscopy (XPS). In order to obtain monocopper sulfide, CuS, named as covellite, the molar recipe ratio of sulfur to copper should be less than 8 in any hydrothermal ageing time. The morphology showed spherical-like structure with energy band gap of 1.88-2.04 eV. CuS was tested for its photocatalytic degradation of paraquat under visible light irradiation. It exhibited excellent activities in the presence of H<sub>2</sub>O<sub>2</sub>. The kinetic of paraquat degradation was also investigated using Langmuir-Hinshelwood-Hougen-Watson (LHHW) model. The reaction rate constant was three times higher than TiO<sub>2</sub> under the same studied conditions.

Preparation, Characterization of Phosphorus Doped Titania Photocatalysts with High Photocatalystic Properties

2010 ◽  
Vol 113-116 ◽  
pp. 2154-2157 ◽  
Author(s):  
Si Yao Guo ◽  
Jin Bing Sun ◽  
Feng Lu Wang ◽  
Lin Yang ◽  
Feng Zhang ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Titania Nanoparticles ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
One Step ◽  
Titania Photocatalyst ◽  
Calcination Method ◽  
Doped Titania

Phosphor-doped titania nanoparticles were synthesized by a one step method, which were prepared by conventional calcination method. These samples have much higher photocatalytic activity for methylene blue degradation. The resulting materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), etc. Moreover, we use high P/TiO2 molar ratio to get the most suitable proportion for the synthesis of P-doped titania photocatalyst.

scholarly journals Evaluation of usage-induced degradation of different endodontic file systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shekhar Bhatia ◽  
Venkatesh Nagendrababu ◽  
Ove A. Peters ◽  
Amr Fawzy ◽  
Umer Daood
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Defects ◽  
File System ◽  
File Systems ◽  
Passive Layer ◽  
Binding Energies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After

AbstractTo evaluate structural profiles and mechanical behaviour of WaveOne Gold (WOG), Twisted File Adaptive (TFA) and XP-endo shaper (XPS) instruments after root canal preparation. Standardized in vitro shaping was performed in presence of 5.25% sodium hypochlorite. File morphology was analyzed using scanning electron microscopy; X-ray diffraction analysis was performed before and after use along with Raman spectroscopy. Nanoindentation was carried out to characterize surface topography. Ni2+ release was measured at 1, 3, 5 and 7 days. X-ray photoelectron spectroscopy (XPS) analysis was done before and after use. After allocating scan line shifts like in WOG, mechanical deformation was shown using first order polynomials. XPS file system showed minimal grooves on surface. SEM of WOG instrument showed scraping surface defects. Hardness varied from 8.11 ± 0.99 GPa in TFA system to 6.7 ± 1.27 GPa and 4.06 ± 4.1 GPa in XPS and WOG. Ni2+ concentration from WOG was 171.2 μg/L. Raman peak at 540–545 cm−1 is attributed to Cr2O3. High resolution of Ti 2p spectrum show distinctive peaks with binding energies dominating in WOG, XPS and TFA file system. XRD exhibited NiTi phases with diffraction peaks. WOG files showed more surface deterioration and less passive layer formation as compared to TFA and XPS systems.

scholarly journals Synthesis of h-BN by the Combustion of B/KNO3/Octogen Mixture under Nitrogen Atmosphere

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Song-qi Hu ◽  
Yin Wang ◽  
Lin-lin Liu
Keyword(s):  
High Purity ◽  
Photoelectron Spectroscopy ◽  
Hexagonal Boron Nitride ◽  
Nitrogen Atmosphere ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistance To Oxidation ◽  
Scanning Electron ◽  
Main Impurity

Hexagonal boron nitride (h-BN) powders were fabricated by the combustion synthesis with B/KNO3/HMX (octogen) mixtures as reactants. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were adopted to investigate the phase composition and the chemical composition of the products, respectively. The morphology and resistance to oxidation were studied by scanning electron microscopy (SEM) and thermogravimetry (TGA), respectively. The characterization results showed that the h-BN which was produced through this method has high purity and exhibits excellent resistance to oxidation. The purity of h-BN is improved with the increasing content of HMX in reactants with boron carbide (B4C) and boron oxide (B2O3) as main impurity, but conversely, the yields are obviously decreased. Taking the comprehensive consideration of the purity and the yields together, the optimal molar ratio of B/KNO3/HMX is 10 : 1 : 4. In addition, the experimental results indicated that the crystalline grain size grows with the increasing content of HMX. The method explored in this study does not need expensive processing facilities and equipment, which is a preferable approach for the laboratory to prepare h-BN of high purity.

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