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Yi Tang - One of the best experts on this subject based on the ideXlab platform.
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controllable and sda free synthesis of sub micrometer sized zeolite zsm 5 part 2 influence of sodium ions and ageing of the Reaction Mixture on the chemical composition crystallinity and particulate properties of the products
Microporous and Mesoporous Materials, 2012Co-Authors: Nan Ren, Josip Bronic, Boris Subotic, Yanmei Song, Yi TangAbstract:Abstract In this work, the influences of excess amount of sodium ions and the way/duration of ageing of the Reaction Mixture (hydrogel) on structural, particulate, morphological and chemical properties of the crystalline end products obtained by hydrothermal treatment (heating at 483 K for 2 h) of the TPA-free Reaction Mixture: 1.0Al 2 O 3 /100SiO 2 / x Na 2 O/4000H 2 O/ y Na 2 SO 4 (0.4 ⩽ ( x + y ) ⩽ 100) seeded by silicalite-1 nanocrystals (260 nm, 4 wt.% of silica in gel Mixture), was investigated by different characterization methods such as, powder X-ray diffraction (XRD), scanning-electron microscopy (SEM), particle size distribution (PSD) measuring by laser light scattering (LLS) and X-ray fluorescence (XRF). The obtained results showed that addition of sodium sulfate in low-alkaline Reaction Mixture enhances the aggregation of the particles of colloidal silica and formation of gel by the action of sulfate oxy-anions while in high-alkaline Reaction Mixtures the condensation process takes place on the surface of the crystalline end products. Excess amount of sodium ions do not increase the crystallization rate thus showing that the rate-determining factor is concentration of “free” low-molecular weight silicate species, determined by the alkalinity of system. On the other hand, addition of sodium sulfate considerably reduces the formation of crystal aggregates, by combined chemical and electrical interactions. Ageing of the Reaction Mixture (hydrogel) mainly influences the particle size distribution of the crystalline end products, which is explained by the change in the relative rates of crystal growth and crystal aggregation with the time of ageing. However, hydrogel ageing does not affect the size and number of crystals in the crystalline end product, showing that the growth precursor particles form during hydrothermal treatment of the Reaction Mixture and not during its room-temperature ageing.
Boris Subotic - One of the best experts on this subject based on the ideXlab platform.
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controllable and sda free synthesis of sub micrometer sized zeolite zsm 5 part 2 influence of sodium ions and ageing of the Reaction Mixture on the chemical composition crystallinity and particulate properties of the products
Microporous and Mesoporous Materials, 2012Co-Authors: Nan Ren, Josip Bronic, Boris Subotic, Yanmei Song, Yi TangAbstract:Abstract In this work, the influences of excess amount of sodium ions and the way/duration of ageing of the Reaction Mixture (hydrogel) on structural, particulate, morphological and chemical properties of the crystalline end products obtained by hydrothermal treatment (heating at 483 K for 2 h) of the TPA-free Reaction Mixture: 1.0Al 2 O 3 /100SiO 2 / x Na 2 O/4000H 2 O/ y Na 2 SO 4 (0.4 ⩽ ( x + y ) ⩽ 100) seeded by silicalite-1 nanocrystals (260 nm, 4 wt.% of silica in gel Mixture), was investigated by different characterization methods such as, powder X-ray diffraction (XRD), scanning-electron microscopy (SEM), particle size distribution (PSD) measuring by laser light scattering (LLS) and X-ray fluorescence (XRF). The obtained results showed that addition of sodium sulfate in low-alkaline Reaction Mixture enhances the aggregation of the particles of colloidal silica and formation of gel by the action of sulfate oxy-anions while in high-alkaline Reaction Mixtures the condensation process takes place on the surface of the crystalline end products. Excess amount of sodium ions do not increase the crystallization rate thus showing that the rate-determining factor is concentration of “free” low-molecular weight silicate species, determined by the alkalinity of system. On the other hand, addition of sodium sulfate considerably reduces the formation of crystal aggregates, by combined chemical and electrical interactions. Ageing of the Reaction Mixture (hydrogel) mainly influences the particle size distribution of the crystalline end products, which is explained by the change in the relative rates of crystal growth and crystal aggregation with the time of ageing. However, hydrogel ageing does not affect the size and number of crystals in the crystalline end product, showing that the growth precursor particles form during hydrothermal treatment of the Reaction Mixture and not during its room-temperature ageing.
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chemically controlled particulate properties of zeolites towards the face less particles of zeolite a 2 influence of aluminosilicate batch concentration and alkalinity of the Reaction Mixture hydrogel on the size and shape of zeolite a crystals
Microporous and Mesoporous Materials, 2011Co-Authors: Sanja Bosnar, Josip Bronic, đurđica Brlek, Boris SuboticAbstract:Abstract Influence of the simultaneous change of batch alkalinity ( A = [Na 2 O/H 2 O] b ) and total batch silica concentration ( tsc = [SiO 2 /H 2 O] b ) of the Reaction Mixture, at two characteristic batch molar ratios, y ≡ [SiO 2 /Al 2 O 3 ] b (1.3 and 2.0), on the duration of crystallization, Reaction yield and the particulate properties (size and shape) of the crystalline end product (zeolite A) was investigated. Sharp decrease of the duration of crystallization process with simultaneous increase of A and tsc is caused by simultaneous increase of the number of nuclei formed in gel matrix, rate of their release from the gel matrix and their growth with the increase of the alkalinity of the Reaction Mixture. Although the Reaction yield, Y R , is proportional to the total batch silica concentration, tsc , the ratio Y R / tsc slightly decreases with increasing alkalinity as a consequence of the increasing solubility of zeolite A with the increase of the alkalinity. Specific number of crystals (number of crystals per unit mass of the crystalline end products), N s increases with simultaneous increase of A and tsc as a consequence of the increase of the number of nuclei formed in the gel matrix with increase of alkalinity of the Reaction Mixture. On the other hand, a complex dependence of the crystal size distribution on A , tsc and y , is a consequence of influence of the mentioned chemical factors not only on the number of nuclei, but also on their distribution in the gel matrix. Four different morphological forms of zeolite A, namely, (i) regular cubic crystals with “sharp” edges and apexes, (ii) cubic crystals with truncated edges, (iii) cubic crystals with “rounded” edges and apexes and (iv) pseudo-spherical, face-less particles are obtained during hydrothermal treatment of investigated hydrogels. Influence of the chemical factors on the formation of particular morphological forms of zeolite A are discussed and the possible mechanisms of their formation are considered.
Josip Bronic - One of the best experts on this subject based on the ideXlab platform.
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controllable and sda free synthesis of sub micrometer sized zeolite zsm 5 part 2 influence of sodium ions and ageing of the Reaction Mixture on the chemical composition crystallinity and particulate properties of the products
Microporous and Mesoporous Materials, 2012Co-Authors: Nan Ren, Josip Bronic, Boris Subotic, Yanmei Song, Yi TangAbstract:Abstract In this work, the influences of excess amount of sodium ions and the way/duration of ageing of the Reaction Mixture (hydrogel) on structural, particulate, morphological and chemical properties of the crystalline end products obtained by hydrothermal treatment (heating at 483 K for 2 h) of the TPA-free Reaction Mixture: 1.0Al 2 O 3 /100SiO 2 / x Na 2 O/4000H 2 O/ y Na 2 SO 4 (0.4 ⩽ ( x + y ) ⩽ 100) seeded by silicalite-1 nanocrystals (260 nm, 4 wt.% of silica in gel Mixture), was investigated by different characterization methods such as, powder X-ray diffraction (XRD), scanning-electron microscopy (SEM), particle size distribution (PSD) measuring by laser light scattering (LLS) and X-ray fluorescence (XRF). The obtained results showed that addition of sodium sulfate in low-alkaline Reaction Mixture enhances the aggregation of the particles of colloidal silica and formation of gel by the action of sulfate oxy-anions while in high-alkaline Reaction Mixtures the condensation process takes place on the surface of the crystalline end products. Excess amount of sodium ions do not increase the crystallization rate thus showing that the rate-determining factor is concentration of “free” low-molecular weight silicate species, determined by the alkalinity of system. On the other hand, addition of sodium sulfate considerably reduces the formation of crystal aggregates, by combined chemical and electrical interactions. Ageing of the Reaction Mixture (hydrogel) mainly influences the particle size distribution of the crystalline end products, which is explained by the change in the relative rates of crystal growth and crystal aggregation with the time of ageing. However, hydrogel ageing does not affect the size and number of crystals in the crystalline end product, showing that the growth precursor particles form during hydrothermal treatment of the Reaction Mixture and not during its room-temperature ageing.
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chemically controlled particulate properties of zeolites towards the face less particles of zeolite a 2 influence of aluminosilicate batch concentration and alkalinity of the Reaction Mixture hydrogel on the size and shape of zeolite a crystals
Microporous and Mesoporous Materials, 2011Co-Authors: Sanja Bosnar, Josip Bronic, đurđica Brlek, Boris SuboticAbstract:Abstract Influence of the simultaneous change of batch alkalinity ( A = [Na 2 O/H 2 O] b ) and total batch silica concentration ( tsc = [SiO 2 /H 2 O] b ) of the Reaction Mixture, at two characteristic batch molar ratios, y ≡ [SiO 2 /Al 2 O 3 ] b (1.3 and 2.0), on the duration of crystallization, Reaction yield and the particulate properties (size and shape) of the crystalline end product (zeolite A) was investigated. Sharp decrease of the duration of crystallization process with simultaneous increase of A and tsc is caused by simultaneous increase of the number of nuclei formed in gel matrix, rate of their release from the gel matrix and their growth with the increase of the alkalinity of the Reaction Mixture. Although the Reaction yield, Y R , is proportional to the total batch silica concentration, tsc , the ratio Y R / tsc slightly decreases with increasing alkalinity as a consequence of the increasing solubility of zeolite A with the increase of the alkalinity. Specific number of crystals (number of crystals per unit mass of the crystalline end products), N s increases with simultaneous increase of A and tsc as a consequence of the increase of the number of nuclei formed in the gel matrix with increase of alkalinity of the Reaction Mixture. On the other hand, a complex dependence of the crystal size distribution on A , tsc and y , is a consequence of influence of the mentioned chemical factors not only on the number of nuclei, but also on their distribution in the gel matrix. Four different morphological forms of zeolite A, namely, (i) regular cubic crystals with “sharp” edges and apexes, (ii) cubic crystals with truncated edges, (iii) cubic crystals with “rounded” edges and apexes and (iv) pseudo-spherical, face-less particles are obtained during hydrothermal treatment of investigated hydrogels. Influence of the chemical factors on the formation of particular morphological forms of zeolite A are discussed and the possible mechanisms of their formation are considered.
Hideo Iwahashi - One of the best experts on this subject based on the ideXlab platform.
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Formation of 7-carboxyheptyl radical induced by singlet oxygen in the Reaction Mixture of oleic acid, riboflavin and ferrous ion under the UVA irradiation.
Journal of Clinical Biochemistry and Nutrition, 2011Co-Authors: Hiroko Mori, Hideo IwahashiAbstract:Identification of the radicals was performed for the standard Reaction Mixtures, which contained 4.3 mM oleic acid, 25 µM riboflavin, 1 mM FeSO4(NH4)2SO4, 10 mM cholic acid, 40 mM phosphate buffer (pH 7.4) and 0.1 M α-(4-pyridyl-1-oxide)-N-tert-butylnitrone under the UVA irradiation (365 nm), using an electron spin resonance, an high performance liquid chromatography-electron spin resonance and an high performance liquid chromatography-electron spin resonance-mass spectrometry. The electron spin resonance and high performance liquid chromatography-electron spin resonance measurements of the standard Reaction Mixtures showed prominent signals (αN = 1.58 mT and αHβ = 0.26 mT) and peaks 1 and 3 (retention times, 37.0 min and 49.0 min). Since the peak 3 was not observed for the standard Reaction Mixture without oleic acid, the radical of the peak 3 seems to be derived from oleic acid. Singlet oxygens seem to participate in the formation of the oleic acid-derived radicals because the peak height of the peak 3 observed in the standard Reaction Mixture of D2O increased to 308 ± 72% of the control. The high performance liquid chromatography-electron spin resonance-mass spectrometry analysis showed that 7-carboxyheptyl radical forms in the standard Reaction Mixture.
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Identification of Radicals Formed in the Reaction Mixture of Bovine Kidney Microsomes with NADPH
Journal of Biochemistry, 2009Co-Authors: Kazumasa Kumamoto, Tomihiro Hirai, Shiroh Kishioka, Hideo IwahashiAbstract:In order to explore the mechanism of myoglobinuric renal toxicity, detection and identification of free radicals was performed for the Reaction Mixtures of bovine kidney microsomes. EPR measurements showed prominent signals for the control Reaction Mixture containing 2.0 mg protein/ml bovine kidney microsomes, 5 mM NADPH, 0.1 M 4-POBN and 29 mM phosphate buffer (pH 7.4). Addition of myoglobin (Mb) to the control Reaction Mixture resulted in increase of EPR peak height. The result indicates that Mb enhances the radical formation. An HPLC-EPR measurement showed three peaks with retention times of 29.4 min (P(1)), 32.4 min (P(2)) and 46.6 min (P(3)). HPLC-EPR-MS analyses of P(1) and P(2) gave ions at m/z 282. The results show that 4-POBN/hydroxypentyl radical adducts form in the Reaction Mixture. An HPLC-EPR-MS analysis of P(3) gave ions at m/z 266, indicating that 4-POBN/pentyl radical adduct forms in the Reaction Mixture.
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Superoxide dismutase enhanced the formation of hydroxyl radicals in a Reaction Mixture containing xanthone under UVA irradiation.
Bioscience Biotechnology and Biochemistry, 2007Co-Authors: Hiroko Mori, Hideo IwahashiAbstract:To clarify the effect of superoxide dismutase (SOD) on the formation of hydroxyl radical in a standard Reaction Mixture containing 15 microM of xanthone, 0.1 M of 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and 45 mM of phosphate buffer (pH 7.4) under UVA irradiation, electron paramagnetic resonance (EPR) measurements were performed. SOD enhanced the formation of hydroxyl radicals. The formation of hydroxyl radicals was inhibited on the addition of catalase. The rate of hydroxyl radical formation also slowed down under a reduced oxygen concentration, whereas it was stimulated by disodium ethylenediaminetetraacetate (EDTA) and diethyleneaminepentaacetic acid (DETAPAC). Above findings suggest that O(2), H(2)O(2), and iron ions participate in the Reaction. SOD possibly enhances the formation of the hydroxyl radical in Reaction Mixtures of photosensitizers that can produce O(2)(-.).
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Identification of Radicals Formed in the Reaction Mixtures of Rat Liver Microsomes with ADP, Fe3+ and NADPH Using HPLC–EPR and HPLC–EPR–MS
Journal of Biochemistry, 2007Co-Authors: Katsuyuki Minakata, Etsuo Okuno, Masayuki Nakamura, Hideo IwahashiAbstract:The Reaction of rat liver microsomes with Fe(3+), ADP and NADPH was examined using EPR, HPLC-EPR and HPLC-EPR-MS combined use of spin trapping technique. A prominent EPR spectrum (alpha(N) = 1.58 mT and alpha(H)beta = 0.26 mT) was observed in the complete Reaction Mixture. The EPR spectrum was hardly observed for the complete Reaction Mixture without rat liver microsomes. The radicals appear to be derived from microsomal components. The EPR spectrum was also hardly observed in the absence of Fe(3+). Addition of some iron chelators such as EDTA, citrate and ADP resulted in the dramatic change in the EPR intensity. Iron ions seem to be essential for this Reaction. For the complete Reaction Mixture with boiled microsomes, a weak EPR spectrum was observed, suggesting that enzymes participate in the Reaction. Five peaks were separated on the HPLC-EPR elution profile of the complete Reaction Mixture of rat liver microsomes with ADP, Fe(3+) and NADPH. The retention times of the peaks 1 to 5 were 19.4, 22.5, 27.3, 29.8 and 31.4 min, respectively. To identify the radical adducts, HPLC-EPR-MS analyses were performed for the three prominent peaks. The HPLC-EPR-MS analyses showed that a new radical adduct, 4-POBN/1-hydroxypentyl radical, in addition to 4-POBN/ethyl radical adducts, forms in a Reaction Mixture of rat liver microsomes with ADP, Fe(3+) and NADPH.
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Identification of a radical formed in the Reaction Mixture of rat brain homogenate with a ferrous ion/ascorbic acid system using HPLC-EPR and HPLC-EPR-MS.
Free Radical Research, 2007Co-Authors: Kazumasa Kumamoto, Tomihiro Hirai, Shiroh Kishioka, Hideo IwahashiAbstract:Identification of a free radical is performed for the Reaction Mixture of rat brain homogenate with a ferrous ion/ascorbic acid system using EPR, high performance liquid chromatography-electron paramagnetic resonance spectrometry (HPLC-EPR) and high performance liquid chromatography-electron paramagnetic resonance-mass spectrometry (HPLC-EPR-MS). EPR measurements of the Reaction Mixtures showed prominent signals with hyperfine coupling constants (alpha(N) = 1.58 mT and alpha(H)beta = 0.26 mT). No EPR spectrum was detectable without rat brain homogenate, suggesting that the radical is derived from rat brain homogenate. An HPLC-EPR analysis of the Reaction Mixture showed a peak with retention time of 33.7 min. An HPLC-EPR-MS analysis of the peak gave two ions at m/z 224 and 137, suggesting that alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN)/ethyl radical adduct forms in the Reaction Mixture.
Nan Ren - One of the best experts on this subject based on the ideXlab platform.
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controllable and sda free synthesis of sub micrometer sized zeolite zsm 5 part 2 influence of sodium ions and ageing of the Reaction Mixture on the chemical composition crystallinity and particulate properties of the products
Microporous and Mesoporous Materials, 2012Co-Authors: Nan Ren, Josip Bronic, Boris Subotic, Yanmei Song, Yi TangAbstract:Abstract In this work, the influences of excess amount of sodium ions and the way/duration of ageing of the Reaction Mixture (hydrogel) on structural, particulate, morphological and chemical properties of the crystalline end products obtained by hydrothermal treatment (heating at 483 K for 2 h) of the TPA-free Reaction Mixture: 1.0Al 2 O 3 /100SiO 2 / x Na 2 O/4000H 2 O/ y Na 2 SO 4 (0.4 ⩽ ( x + y ) ⩽ 100) seeded by silicalite-1 nanocrystals (260 nm, 4 wt.% of silica in gel Mixture), was investigated by different characterization methods such as, powder X-ray diffraction (XRD), scanning-electron microscopy (SEM), particle size distribution (PSD) measuring by laser light scattering (LLS) and X-ray fluorescence (XRF). The obtained results showed that addition of sodium sulfate in low-alkaline Reaction Mixture enhances the aggregation of the particles of colloidal silica and formation of gel by the action of sulfate oxy-anions while in high-alkaline Reaction Mixtures the condensation process takes place on the surface of the crystalline end products. Excess amount of sodium ions do not increase the crystallization rate thus showing that the rate-determining factor is concentration of “free” low-molecular weight silicate species, determined by the alkalinity of system. On the other hand, addition of sodium sulfate considerably reduces the formation of crystal aggregates, by combined chemical and electrical interactions. Ageing of the Reaction Mixture (hydrogel) mainly influences the particle size distribution of the crystalline end products, which is explained by the change in the relative rates of crystal growth and crystal aggregation with the time of ageing. However, hydrogel ageing does not affect the size and number of crystals in the crystalline end product, showing that the growth precursor particles form during hydrothermal treatment of the Reaction Mixture and not during its room-temperature ageing.
