Facile, Alternative Synthesis of Spherical-Like Ca(H2PO4)2•H2O Nanoparticle by Aqueous-Methanol Media

2013 ◽  
Vol 717 ◽  
pp. 49-53 ◽  
Author(s):  
Samart Kongteweelert ◽  
Chesta Ruttanapun ◽  
Montree Thongkam ◽  
Pachernchaipat Chaiyasith ◽  
Somsak Woramongkonchai ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Calcium Carbonate ◽  
Ambient Temperature ◽  
Calcium Phosphates ◽  
Aqueous Methanol ◽  
Simple Method ◽  
Alternative Synthesis ◽  
Prepared Sample ◽  
Decomposition Step ◽  
Potential Applications

Spherical-like calcium dihydrogenphosphate monohydrate (Ca (H2PO4)2H2O) nanostructure was successfully prepared by the mixing of calcium carbonate and phosphoric in aqueous-methanol media at ambient temperature for 30 min. Three thermal decomposition step and higher stability at over 800 °C of the prepared sample are different from the earlier works. Spherical-like Ca (H2PO4)2H2O nanostructure with diameter < 100 nm confirmed by SEM may be important for potential applications. This method of synthesis by aqueous-methanol media is a fast and simple method and it is expected to be applicable for the synthesis of other nanocrystalline calcium phosphates.

scholarly journals Optimising the DPPH Assay for Cell-Free Marine Microorganism Supernatants

Marine Drugs ◽  
2021 ◽  
Vol 19 (5) ◽  
pp. 256
Author(s):  
Yehui Gang ◽  
Tae-Yang Eom ◽  
Svini Dileepa Marasinghe ◽  
Youngdeuk Lee ◽  
Eunyoung Jo ◽  
...  
Keyword(s):  
Water Content ◽  
Antioxidant Activities ◽  
Fermented Foods ◽  
Solution Stability ◽  
Marine Microorganism ◽  
Marine Microorganisms ◽  
Dpph Assay ◽  
Aqueous Methanol ◽  
Potential Applications ◽  
Pseudoalteromonas Rubra

Antioxidants prevent ageing and are usually quantified and screened using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. However, this assay cannot be used for salt-containing samples, such as the cell-free supernatants of marine microorganisms that are aggregated under these conditions. Herein, the DPPH solvent (methanol or ethanol) and its water content were optimized to enable the analysis of salt-containing samples, aggregation was observed for alcohol contents of >70%. The water content of methanol influenced the activities of standard antioxidants but did not significantly affect that of the samples. Based on solution stability considerations, 70% aqueous methanol was chosen as the optimal DPPH solvent. The developed method was successfully applied to the cell-free supernatants of marine bacteria (Pseudoalteromonas rubra and Pseudoalteromonas xiamenensis), revealing their high antioxidant activities. Furthermore, it was concluded that this method would be useful for the screening of marine microorganism–derived antioxidants, which also has numerous potential applications, such as salt-fermented foods.

Effects of Ca2+ Concentration on Calcium Carbonate Crystallization in Lignin Solution System

2011 ◽  
Vol 695 ◽  
pp. 521-524 ◽  
Author(s):  
Wen Kun Zhu ◽  
Xue Gang Luo ◽  
Xiao Yan Lin ◽  
Pan He
Keyword(s):  
Thermal Decomposition ◽  
Calcium Carbonate ◽  
Solution System ◽  
Uniform Size ◽  
Ft Ir

The calcium carbonate crystallization was controlled by Ca2+concentrations, under the system of lignin solution with concentration of 10 g / L. Its morphology, structure and thermal decomposition were characterized by FT-IR, SEM, XRD and TG. Results showed that in lignin solution system, concentration of Ca2+had significant effects on the crystallized morphology, orientation and crystallinity of calcium carbonate. Calcium carbonate crystal under low Ca2+concentration had more uniform size while under high Ca2+concentration which tended to form various sizes with more complete crystallization. The calcium carbonate crystals were all calcite calcium carbonate, which formed under different Ca2+concentrations.

The thermal decomposition of RDX at temperatures below the melting point. V. The evolution of occluded volatile matter prior to the decomposition, and the influence of past history of the sample on the rate of decomposition

1972 ◽  
Vol 25 (11) ◽  
pp. 2337 ◽  
Author(s):  
JJ Batten
Keyword(s):  
Thermal Decomposition ◽  
Reaction Time ◽  
Melting Point ◽  
Ambient Temperature ◽  
Ultraviolet Light ◽  
Past History ◽  
Volatile Matter ◽  
Post Irradiation ◽  
Mechanism Of Decomposition ◽  
History Of

It is fist demonstrated that the occluded solvents and gases which are often present in RDX are expelled prior to zero reaction time of thermal decomposition. Thus they do not seriously interfere with the use of pressure increase as a measure of the extent of thermal decomposition. The rate of thermal decomposition of sublimed RDX at 195�C is then compared with the rate after the following treatments, (i) preliminary grinding of the crystals, (ii) preparation of the crystals by different techniques, (iii) mixing RDX with various solid additives, (iv) interruption of the reaction by cooling, and (v) pre-irradiation with ultraviolet light. The results indicated that treatments (i), (ii), and (iv) had little effect on the rate, whereas (iii) and (v) could markedly influence the rate. Their effects are discussed in terms of the mechanism of decomposition. The results also indicated that there was a post-irradiation reaction of RDX at ambient temperature.

Calcium Carbonate and Cellulose/Calcium Carbonate Composites: Synthesis, Characterization, and Biomedical Applications

2016 ◽  
Vol 875 ◽  
pp. 24-44
Author(s):  
Ming Guo Ma ◽  
Shan Liu ◽  
Lian Hua Fu
Keyword(s):  
Calcium Carbonate ◽  
Biomedical Applications ◽  
Value Added ◽  
Functional Materials ◽  
Industrial Applications ◽  
Precipitation Method ◽  
Synthesis Methods ◽  
Water Pretreatment ◽  
Potential Applications ◽  
Co Precipitation

CaCO3 has six polymorphs such as vaterite, aragonite, calcite, amorphous, crystalline monohydrate, and hexahydrate CaCO3. CaCO3 is a typical biomineral that is abundant in both organisms and nature and has important industrial applications. Cellulose could be used as feedstocks for producing biofuels, bio-based chemicals, and high value-added bio-based materials. In the past, more attentions have been paid to the synthesis and applications of CaCO3 and cellulose/CaCO3 nanocomposites due to its relating properties such as mechanical strength, biocompatibility, and biodegradation, and bioactivity, and potential applications including biomedical, antibacterial, and water pretreatment fields as functional materials. A variety of synthesis methods such as the hydrothermal/solvothermal method, biomimetic mineralization method, microwave-assisted method, (co-) precipitation method, and sonochemistry method, were employed to the preparation of CaCO3 and cellulose/CaCO3 nanocomposites. In this chapter, the recent development of CaCO3 and cellulose/CaCO3 nanocomposites has been reviewed. The synthesis, characterization, and biomedical applications of CaCO3 and cellulose/CaCO3 nanocomposites are summarized. The future developments of CaCO3 and cellulose/CaCO3 nanocomposites are also suggested.

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