The Experts below are selected from a list of 876 Experts worldwide ranked by ideXlab platform
Petra Mácová - One of the best experts on this subject based on the ideXlab platform.
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polyamorphism and frustrated Crystallization in the acid base reaction of magnesium potassium phosphate cements
CrystEngComm, 2018Co-Authors: Alberto Viani, Petra MácováAbstract:Magnesium potassium phosphate cements are a class of acid–base cements for bioengineering and civil engineering applications. The kinetics of their chemical reaction was investigated in situ with isothermal conduction calorimetry and powder X-ray diffraction, quantifying amorphous and Crystalline products. The first reaction step, dissolution of MgO, with an apparent activation energy of 71 kJ mol−1, dictates the time evolution of two amorphous intermediate precursors and the Crystalline product. The early Crystallization of the latter has been described with an Avrami equation with an apparent activation energy of 81 kJ mol−1, pointing to a mechanism of deceleratory nucleation and growth in one direction, compatible with the Acicular Crystal habit observed with electron microscopy. The observed polyamorph transformation is controlled by a complex interplay between kinetic and thermodynamic factors, in which the changes in the chemical environment (increase in pH) driven by the MgO dissolution, play a crucial role. It is proposed that the onset of the amorphous–amorphous transformation hinders Crystallization by decreasing ion mobility, raising the energy barriers to structural reorganization. The rate of MgO dissolution depends on the reactivity of the powder and the parameters of the mix (such as the amount of liquid) and influences the reaction pathways, impacting on material performance.
Kazumi Kato - One of the best experts on this subject based on the ideXlab platform.
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high protein adsorption characteristics of Acicular Crystal assembled tio2 films and their photoelectric effect
Thin Solid Films, 2011Co-Authors: Yoshitake Masuda, Kazumi Kato, Tatsuki Ohji, Masako Ajimi, Makoto Bekki, Shuji SonezakiAbstract:Abstract Unique structures of TiO2 films were prepared on F-doped SnO2 transparent conductive films in aqueous solutions. They were then covered with dye-labeled proteins. Firstly, influence of film thickness on photoluminescence intensity (PL) and photocurrent (PC) was investigated. PL and PC were improved with the decrease of film thickness. Especially, PC was drastically improved to more than 30 times with the decrease of film thickness. Secondly, a novel technique of solution aging method was applied to form TiO2 structures. PC was successfully improved with this technique. They were candidate materials for bio-semiconductor hybrid devices such as protein sensors.
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optical properties and dye adsorption characteristics of Acicular Crystal assembled tio2 thin films
Journal of Crystal Growth, 2009Co-Authors: Yoshitake Masuda, Kazumi KatoAbstract:Abstract Fluorine doped tin oxide (FTO) substrates were modified with Acicular Crystal assembled TiO2 thin films. The thin films increased transparency and decreased reflectance of the substrates. The films had high transparency over 80% in the range from 400 to 850 nm. They were about 8% higher than those of bare FTO substrates. The films had low reflectance of about 11% in the range from 350 to 850 nm. They were about 3% lower than those of bare FTO areas. Nano-sized surface relief structures of the films functioned as antireflection coatings. Additionally, dye adsorption properties of the substrates were improved by formation of the thin films. It was 70 times higher than that of bare FTO substrates and reached 12 times of TiO2 particulate films prepared by TiO2 nanoparticles (P25, Degussa). High transparency and high dye adsorption properties were important factors for sensors and dye-sensitized solar cells. The Acicular Crystal assembled TiO2 thin films are thus candidate materials for these applications.
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Acicular Crystal-assembled TiO2 thin films and their deposition mechanism
Journal of Crystal Growth, 2009Co-Authors: Yoshitake Masuda, Kazumi KatoAbstract:Abstract Acicular Crystal-assembled TiO 2 thin films were prepared on fluorine-doped tin oxide (FTO) substrates in aqueous solutions. They consisted of anatase Crystals grown along the c -axis, which caused high c -axis orientation in X-ray diffraction patterns and electron diffraction patterns. Morphologies of TiO 2 Crystals were controlled by growth conditions to fabricate several types of TiO 2 thin films. Furthermore, deposition mechanism of Acicular Crystals was investigated by comparison of Crystal morphologies deposited for different immersion periods using solution aging method.
Yoshitake Masuda - One of the best experts on this subject based on the ideXlab platform.
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high protein adsorption characteristics of Acicular Crystal assembled tio2 films and their photoelectric effect
Thin Solid Films, 2011Co-Authors: Yoshitake Masuda, Kazumi Kato, Tatsuki Ohji, Masako Ajimi, Makoto Bekki, Shuji SonezakiAbstract:Abstract Unique structures of TiO2 films were prepared on F-doped SnO2 transparent conductive films in aqueous solutions. They were then covered with dye-labeled proteins. Firstly, influence of film thickness on photoluminescence intensity (PL) and photocurrent (PC) was investigated. PL and PC were improved with the decrease of film thickness. Especially, PC was drastically improved to more than 30 times with the decrease of film thickness. Secondly, a novel technique of solution aging method was applied to form TiO2 structures. PC was successfully improved with this technique. They were candidate materials for bio-semiconductor hybrid devices such as protein sensors.
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optical properties and dye adsorption characteristics of Acicular Crystal assembled tio2 thin films
Journal of Crystal Growth, 2009Co-Authors: Yoshitake Masuda, Kazumi KatoAbstract:Abstract Fluorine doped tin oxide (FTO) substrates were modified with Acicular Crystal assembled TiO2 thin films. The thin films increased transparency and decreased reflectance of the substrates. The films had high transparency over 80% in the range from 400 to 850 nm. They were about 8% higher than those of bare FTO substrates. The films had low reflectance of about 11% in the range from 350 to 850 nm. They were about 3% lower than those of bare FTO areas. Nano-sized surface relief structures of the films functioned as antireflection coatings. Additionally, dye adsorption properties of the substrates were improved by formation of the thin films. It was 70 times higher than that of bare FTO substrates and reached 12 times of TiO2 particulate films prepared by TiO2 nanoparticles (P25, Degussa). High transparency and high dye adsorption properties were important factors for sensors and dye-sensitized solar cells. The Acicular Crystal assembled TiO2 thin films are thus candidate materials for these applications.
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Acicular Crystal-assembled TiO2 thin films and their deposition mechanism
Journal of Crystal Growth, 2009Co-Authors: Yoshitake Masuda, Kazumi KatoAbstract:Abstract Acicular Crystal-assembled TiO 2 thin films were prepared on fluorine-doped tin oxide (FTO) substrates in aqueous solutions. They consisted of anatase Crystals grown along the c -axis, which caused high c -axis orientation in X-ray diffraction patterns and electron diffraction patterns. Morphologies of TiO 2 Crystals were controlled by growth conditions to fabricate several types of TiO 2 thin films. Furthermore, deposition mechanism of Acicular Crystals was investigated by comparison of Crystal morphologies deposited for different immersion periods using solution aging method.
Alberto Viani - One of the best experts on this subject based on the ideXlab platform.
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polyamorphism and frustrated Crystallization in the acid base reaction of magnesium potassium phosphate cements
CrystEngComm, 2018Co-Authors: Alberto Viani, Petra MácováAbstract:Magnesium potassium phosphate cements are a class of acid–base cements for bioengineering and civil engineering applications. The kinetics of their chemical reaction was investigated in situ with isothermal conduction calorimetry and powder X-ray diffraction, quantifying amorphous and Crystalline products. The first reaction step, dissolution of MgO, with an apparent activation energy of 71 kJ mol−1, dictates the time evolution of two amorphous intermediate precursors and the Crystalline product. The early Crystallization of the latter has been described with an Avrami equation with an apparent activation energy of 81 kJ mol−1, pointing to a mechanism of deceleratory nucleation and growth in one direction, compatible with the Acicular Crystal habit observed with electron microscopy. The observed polyamorph transformation is controlled by a complex interplay between kinetic and thermodynamic factors, in which the changes in the chemical environment (increase in pH) driven by the MgO dissolution, play a crucial role. It is proposed that the onset of the amorphous–amorphous transformation hinders Crystallization by decreasing ion mobility, raising the energy barriers to structural reorganization. The rate of MgO dissolution depends on the reactivity of the powder and the parameters of the mix (such as the amount of liquid) and influences the reaction pathways, impacting on material performance.
Jing Cai - One of the best experts on this subject based on the ideXlab platform.
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hydrate based co2 carbon dioxide capture from igcc integrated gasification combined cycle synthesis gas using bubble method with a set of visual equipment
Energy, 2012Co-Authors: Zhaoyang Chen, Jing CaiAbstract:Abstract The hydrate-based carbon dioxide (CO2) capture from the integrated gasification combined cycle (IGCC) synthesis gas using the bubble method is investigated with a set of visual equipment in this work. The gas bubble is created with a bubble plate on the bottom of the equipment. By the visual equipment, the hydrate formation and the hydrate shape are visually captured. With the move of the gas bubble from the bottom to the top of the reactor, gas hydrate forms firstly from the gas–liquid boundary around the bubble, then the hydrate gradually grows up and piles up in the bottom side of the bubble to form a hydrate particle. The gas hydrate shape is affected by the gas flow rate. The hydrate is Acicular Crystal at the low gas flow rate while the hydrate is fine sand-like Crystal at the high gas flow rate. The bubble size and the gas flow rate have an obvious impact on the hydrate-based CO2 separation process. The experimental results show the gas bubble of 50 μm and the gas flow rate of 6.75 mL/min/L are ideal for CO2 capture from IGCC synthesis gas under the condition of 3.0 MPa and 274.15 K.
