Phase Transformation of TiO2 in the Preparation of Pearlescent Pigment

2007 ◽  
Vol 544-545 ◽  
pp. 99-102
Author(s):  
Tae Gun Kim ◽  
Hae Joeng Kim ◽  
Jeong Ja Kim ◽  
Sung Woong Kim ◽  
Seong Soo Park ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transformation ◽  
Thin Layer ◽  
Crystallite Size ◽  
Pronounced Effect ◽  
Initial Stage ◽  
Hydrolysis Of ◽  
Pearlescent Pigment

The TiO2/mica pearlescent pigments were prepared by the hydrolysis of TiOCl2 on the natural mica (muscovite) followed by a calcinations process. The phase transformation of anatase to rutile during calcination and their proportion in the TiO2 thin layer have been analyzed by XRD measurements. The pH controlling during the initial stage of hydrolysis of TiOCl2 showed a pronounced effect on the phase transformation of TiO2 on the substrate. This result may be due to the fact that the pH controlling during the hydrolysis affects the crystal structure and size of TiO2. The decrease in crystallinity and crystallite size of TiO2 resulted in lowering the temperature of phase transformation from anatase to rutile.

scholarly journals The Effect of Crystallization and Phase Transformation on the Mechanical and Electrochemical Corrosion Properties of Ni-P Coatings

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 447
Author(s):  
Martin Buchtík ◽  
Leoš Doskočil ◽  
Roman Brescher ◽  
Pavel Doležal ◽  
Jiří Másilko ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Crystallite Size ◽  
Electrochemical Corrosion ◽  
Az91 Magnesium Alloy ◽  
Scanning Calorimetry ◽  
Corrosion Properties ◽  
High Phosphorus ◽  
P Content ◽  
Az91 Magnesium ◽  
Increasing Temperature

This paper deals with the study of the crystallization and phase transformation of Ni-P coatings deposited on AZ91 magnesium alloy. Prepared samples were characterized in terms of surface morphology and elemental composition by means of scanning electron microscopy with energy-dispersive spectroscopy analysis. The results of X-ray diffraction analysis and differential scanning calorimetry suggested that increasing the phosphorus content caused Ni-P coatings to develop an amorphous character. The crystallization of Ni was observed at 150, 250, and 300 °C for low-, medium- and high-phosphorus coatings, respectively. The Ni crystallite size increased with increasing temperature and decreasing P content. Conversely, the presence of the Ni3P phase was observed at a maximum peak of 320 °C for the high-phosphorus coating, whereas the crystallization of the Ni3P phase shifted to higher temperatures with decreasing P content. The Ni3P crystallite size increased with increasing temperature and increasing P content. An increase in microhardness due to the arrangement of Ni atoms and Ni3P precipitation was observed. The deposition of as-deposited Ni-P coatings led to an improvement in the corrosion resistance of AZ91. However, the heat treatment of coatings resulted in a deterioration in corrosion properties due to the formation of microcracks.

scholarly journals Crystal structure of thermostable alkylsulfatase SdsAP from Pseudomonas sp. S9

2017 ◽  
Vol 37 (3) ◽  
Author(s):  
Lifang Sun ◽  
Pu Chen ◽  
Yintao Su ◽  
Zhixiong Cai ◽  
Lingwei Ruan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Sodium Dodecyl ◽  
Titration Calorimetry ◽  
Pseudomonas Sp ◽  
Sterol Carrier Protein ◽  
Dimerization Domain ◽  
Alkyl Chains ◽  
Hydrolysis Of

A novel alkylsulfatase from bacterium Pseudomonas sp. S9 (SdsAP) was identified as a thermostable alkylsulfatases (type III), which could hydrolyze the primary alkyl sulfate such as sodium dodecyl sulfate (SDS). Thus, it has a potential application of SDS biodegradation. The crystal structure of SdsAP has been solved to a resolution of 1.76 Å and reveals that SdsAP contains the characteristic metallo-β-lactamase-like fold domain, dimerization domain, and C-terminal sterol carrier protein type 2 (SCP-2)-like fold domain. Kinetic characterization of SdsAP to SDS by isothermal titration calorimetry (ITC) and enzymatic activity assays of constructed mutants demonstrate that Y246 and G263 are important residues for its preference for the hydrolysis of ‘primary alkyl’ chains, confirming that SdsAP is a primary alkylsulfatase.

scholarly journals Effect of calcination temperature and calcination time on the kaolinite/tio2 composite for photocatalytic reduction of CO2

2012 ◽  
Vol 58 (4) ◽  
pp. 10-22 ◽  
Author(s):  
Martin Reli ◽  
Kamila Kočí ◽  
Vlastimil Matějka ◽  
Pavel Kovář ◽  
Lucie Obalová
Keyword(s):  
Crystallite Size ◽  
Physical Adsorption ◽  
Photocatalytic Reduction ◽  
Thermal Hydrolysis ◽  
Calcination Time ◽  
Different Temperatures ◽  
Higher Temperature ◽  
Titanyl Sulphate ◽  
Reduction Of Co2 ◽  
Hydrolysis Of

Abstract The kaolinite/TiO2 composite (60 wt% of TiO2) was prepared by thermal hydrolysis of a raw kaolin suspension in titanyl sulphate and calcined at different temperatures (600, 650 and 700°C) and for different times (1, 2 and 3 h). The obtained samples were characterized by XRPD, N2 physical adsorption and SEM, and tested for photocatalytic reduction of CO2. The different calcination conditions did not influence TiO2 phase composition, only slightly changed the specific surface area, and significantly affected crystallite size of kaolinite/TiO2 composite. A higher temperature and longer duration of calcination lead to higher crystallinity of the powder. The photocatalytic results showed that the crystallite size determined the efficiency of kaolinite/TiO2 photocatalysts.

The crystal structure of human mitochondrial 3-ketoacyl-CoA thiolase (T1): insight into the reaction mechanism of its thiolase and thioesterase activities

2014 ◽  
Vol 70 (12) ◽  
pp. 3212-3225 ◽  
Author(s):  
Tiila-Riikka Kiema ◽  
Rajesh K. Harijan ◽  
Malgorzata Strozyk ◽  
Toshiyuki Fukao ◽  
Stefan E. H. Alexson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Reaction Mechanism ◽  
Active Site ◽  
Quaternary Structure ◽  
Fatty Acyl ◽  
Physiological Importance ◽  
Loop Domain ◽  
Solution Studies ◽  
Hydrolysis Of ◽  
Insight Into

Crystal structures of human mitochondrial 3-ketoacyl-CoA thiolase (hT1) in the apo form and in complex with CoA have been determined at 2.0 Å resolution. The structures confirm the tetrameric quaternary structure of this degradative thiolase. The active site is surprisingly similar to the active site of theZoogloea ramigerabiosynthetic tetrameric thiolase (PDB entries 1dm3 and 1m1o) and different from the active site of the peroxisomal dimeric degradative thiolase (PDB entries 1afw and 2iik). A cavity analysis suggests a mode of binding for the fatty-acyl tail in a tunnel lined by the Nβ2–Nα2 loop of the adjacent subunit and the Lα1 helix of the loop domain. Soaking of the apo hT1 crystals with octanoyl-CoA resulted in a crystal structure in complex with CoA owing to the intrinsic acyl-CoA thioesterase activity of hT1. Solution studies confirm that hT1 has low acyl-CoA thioesterase activity for fatty acyl-CoA substrates. The fastest rate is observed for the hydrolysis of butyryl-CoA. It is also shown that T1 has significant biosynthetic thiolase activity, which is predicted to be of physiological importance.

scholarly journals ISOLATION AND ANALYSIS OF STEROIDAL SAPONINS FROM POLYGONATUM ODORATUM (MILL.) DRUCE

2021 ◽  
Vol 55 ◽  
pp. 135-140
Author(s):  
Cristina MOGOSAN ◽  
Ilioara ONIGA ◽  
Mircea TAMAS
Keyword(s):  
Thin Layer ◽  
Acid Hydrolysis ◽  
Thin Layer Chromatography ◽  
Biological Properties ◽  
Steroidal Saponins ◽  
Physico Chemical ◽  
Layer Chromatography ◽  
Hydrolysis Of

We isolated the steroidal saponins from the rhizomes of Polygonatum odoratum (Mill.) Druce with an efficiency of 4.50% which represents 7 fractions identified by thin-layer chromatography (TLC), of which 3 were furostanics and 4 spirostanics. After the acid hydrolysis of the saponins, one aglycone (sapogenine) was identified by TLC. Further, we have determined the physico-chemical and the biological properties of the isolated saponins.

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