The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Santanu Paria - One of the best experts on this subject based on the ideXlab platform.
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self assembly of colloidal sulfur particles influenced by sodium Oxalate Salt on glass surface from evaporating drops
Soft Matter, 2012Co-Authors: Naveen Noah Jason, Rajib Ghosh Chaudhuri, Santanu PariaAbstract:Evaporation of sessile droplets containing colloidal particles induces outward flow within the drop, which produces the well-known “coffee-ring” effect or a dense ring-like deposition along the perimeter. In this work, the formation of a self-assembled structure during drying of microlitre drops on the glass surface, containing colloidal sulfur particles (synthesized in situ by the reaction of oxalic acid and sodium thiosulphate), is investigated experimentally with help of optical microscopy. Our results show that the particles are self-assembled into a tree-like structure after the evaporation of liquid drops taken from the reaction mixture. The sulfur particles alone cannot form similar self-assembly structures in pure water, but the sodium Oxalate Salt present in the reaction mixture helps to form the tree-like structure. The structure formation is also influenced by evaporative flux inside the liquid drop, and capillary and van der Waals attractive forces between the particles. The different parameters such as particle size, particle and Salt concentration, acid to thiosulphate ratio, drop volume and addition of surfactants strongly influences the structure formation.
Naveen Noah Jason - One of the best experts on this subject based on the ideXlab platform.
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Self-assembly of colloidal sulfur particles on flat surfaces from evaporating sessile drops
2020Co-Authors: Naveen Noah JasonAbstract:The advancement of modern science and technology needs day by day smaller microprocessors, chips, sensors, machines, and devices, as a results, the existing methods of fabrication are slowly becoming obsolete. The fabrication of devices at small scale by the help of self-assembly is an inexpensive and promising technique. This work explores the formation of nano-microstructures using colloidal sulfur particles and the manipulation of their morphology using different acid Salts, surfactants and substrates. Evaporation of sessile droplets containing colloidal particles induces outward flow within the drop, which producews the well-known “coffee-ring” effect or a dense ring-like deposition along the perimeter. In this work, the formation of self-assembled structure during drying of microliter drops on the glass surface containing colloidal sulfur particles (synthesized in situ by the reaction of oxalic acid and sodium thiosulphate) is investigated experimentally with helpof optical microscopy. Our results show that the particles are self-assembled into a tree-like structure after the evaporation of liquid drops from the reaction mixture.he sulfur particles alone cannot form similar self-assembly structurein pure water, but the sodium Oxalate Salt present in the reaction mixture helps to form the tree-like structure. The structure formation is also influenced by evaporation flux inside the liquid drop, capillary, van der Waals attractive forces between the particles. The different parameters such as particle size, particle and Salt concentrations, acid to thiosulphate ratio, drop volume, addition of surfactants strongly influences the structure formation. By varying the acids that are used for the reaction, the resultant Salts are varied too and this brings about changes in the sulfur structure morphology. By using HCI the sulfur structure turns into a labyrinthine grid like structure with almost 90 0 branches growing from the main stems, which are also at 90 0 to each other. With h2so4 similar leaf like patterns as before were obtained, but they were somewhat more angular and rougher. Also by changing the substrate in which the self-assembly takes place, by coating glass slides with surfactants, or by using a polyester substrate the structure morphology can be influenced to a large extent.
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self assembly of colloidal sulfur particles influenced by sodium Oxalate Salt on glass surface from evaporating drops
Soft Matter, 2012Co-Authors: Naveen Noah Jason, Rajib Ghosh Chaudhuri, Santanu PariaAbstract:Evaporation of sessile droplets containing colloidal particles induces outward flow within the drop, which produces the well-known “coffee-ring” effect or a dense ring-like deposition along the perimeter. In this work, the formation of a self-assembled structure during drying of microlitre drops on the glass surface, containing colloidal sulfur particles (synthesized in situ by the reaction of oxalic acid and sodium thiosulphate), is investigated experimentally with help of optical microscopy. Our results show that the particles are self-assembled into a tree-like structure after the evaporation of liquid drops taken from the reaction mixture. The sulfur particles alone cannot form similar self-assembly structures in pure water, but the sodium Oxalate Salt present in the reaction mixture helps to form the tree-like structure. The structure formation is also influenced by evaporative flux inside the liquid drop, and capillary and van der Waals attractive forces between the particles. The different parameters such as particle size, particle and Salt concentration, acid to thiosulphate ratio, drop volume and addition of surfactants strongly influences the structure formation.
Justin Nenwa - One of the best experts on this subject based on the ideXlab platform.
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Anionic Nanochanneled Silver-Deficient Oxalatochromate(III) Complex with Hydroxonium as Counter Ion: Synthesis, Characterization and Crystal Structure
2017Co-Authors: Clémence T. Eboga, Yves A Mbiangue, Gouet Bebga, Emmanuel N. Nfor, Patrick L. Djonwouo, Michel M. Bélombé, Justin NenwaAbstract:Reaction of Ba0.50[Ag2Cr(C2O4)3]·5H2O with Ag2SO4 in an aqueous solution of sulfuric acid (pH ≈ 3) yielded the silver(I)/chromium(III) Oxalate Salt H0.50[Ag2.50Cr(C2O4)3]·5H2O (1). Compound 1 can be best described as an anionic silver-deficient oxalatochromate(III) complex [Ag2.50Cr(C2O4)3]0.5- with nanochannels containing hydrogen-bonded water molecules and protons. Thermal analyses show significant weight losses corresponding to the elimination of water molecules of crystallization followed by the decomposition of the network.
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synthesis characterization and x ray structure of a ba ii ag i cr iii Oxalate Salt with water filled nanochannels
American Journal of Analytical Chemistry, 2016Co-Authors: Clemence Eboga Tanke, Bridget N Ndosiri, Yves A Mbiangue, Gouet Bebga, Justin NenwaAbstract:A novel mixed barium(II)/silver(I)/chromium(III) Oxalate Salt, Ba0.5Ag2[Cr(C2O4)3]·5H2O (1), with open architecture has been synthesized in water and characterized by elemental analysis, vibrational and electronic spectra, and single crystal X-ray structure determination. Compound 1 crystallizes in a monoclinic space group C2/c, with unit cell parameters a = 18.179(3), b = 14.743(2), c = 12.278(2)A, β = 113.821(3), V = 3010.34(90) A3, Z = 8. The structure is characterized by a network of anionic [Cr(C2O4)3]3- units connected through the O atoms of the Oxalates to Ba2+ and Ag+ sites, forming a three-dimensional coordination polymer with one-dimensional isolated nanochannels parallel to the c axis, and encapsulating hydrogen-bonded guest water molecules. The bulk structure is consolidated by O–H···O bridgings within the nanochannels and by coulombic interactions.
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Synthesis, Characterization and X-Ray Structure of a Ba(II)/Ag(I)/Cr(III)-Oxalate Salt with Water-Filled Nanochannels
American Journal of Analytical Chemistry, 2016Co-Authors: Clemence Eboga Tanke, Bridget N Ndosiri, Yves A Mbiangue, Gouet Bebga, Justin NenwaAbstract:A novel mixed barium(II)/silver(I)/chromium(III) Oxalate Salt, Ba0.5Ag2[Cr(C2O4)3]·5H2O (1), with open architecture has been synthesized in water and characterized by elemental analysis, vibrational and electronic spectra, and single crystal X-ray structure determination. Compound 1 crystallizes in a monoclinic space group C2/c, with unit cell parameters a = 18.179(3), b = 14.743(2), c = 12.278(2)A, β = 113.821(3), V = 3010.34(90) A3, Z = 8. The structure is characterized by a network of anionic [Cr(C2O4)3]3- units connected through the O atoms of the Oxalates to Ba2+ and Ag+ sites, forming a three-dimensional coordination polymer with one-dimensional isolated nanochannels parallel to the c axis, and encapsulating hydrogen-bonded guest water molecules. The bulk structure is consolidated by O–H···O bridgings within the nanochannels and by coulombic interactions.
Dario Braga - One of the best experts on this subject based on the ideXlab platform.
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crystal forms of the hydrogen Oxalate Salt of o desmethylvenlafaxine
Journal of Pharmacy and Pharmacology, 2015Co-Authors: Elena Dichiarante, Marco Curzi, Stefano Luca Giaffreda, Fabrizia Grepioni, Lucia Maini, Dario BragaAbstract:Objectives To prepare new crystalline forms of the antidepressant o-desmethylvenlafaxine Salt as potential new commercial forms and evaluate their physicochemical properties, in particular the dissolution rate. Methods A new hydrogen Oxalate Salt of o-desmethylvenlafaxine hydrogen Oxalate (ODV-OX) was synthesized, and a polymorph screening was performed using different solvents and crystallization conditions. Crystalline forms were characterized by a combination of solid-state techniques: X-ray powder diffraction, differential scanning calorimetry, thermogravimetric analysis, FT-IR spectroscopy and single crystal X-ray diffraction. The stability of all crystalline phases was tested under International Conference on Harmonisation (ICH) conditions (40°C and 75% Relative Humidity (RH)) for 1 week. Dissolution tests were performed on the hydrogen Oxalate Salt ODV-OX Form 1 and compared with dissolution test on the commercial form of the succinate Salt of o-desmethylvenlafaxine. Key findings Five crystalline forms of ODV-OX were isolated, namely three hydrated forms (Form 1, Form 2, Form 3) and two anhydrous forms (Form 4 and Form 5). Conclusions Comparative solubility tests on ODV-OX Form 1 and o-desmethylvenlafaxine succinate evidenced a significant increase in solubility for the hydrogen Oxalate Salt (142 g/l) with respect to the succinate Salt (70 g/l).
Changsik Ju - One of the best experts on this subject based on the ideXlab platform.
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Preparation of indium oxide from waste indium tin oxide targets by oxalic acid
Korean Journal of Chemical Engineering, 2017Co-Authors: Changsik JuAbstract:Indium oxide manufacturing process from waste indium tin oxide (ITO) targets by oxalic acid was experimentally studied. The process was composed of precipitation of intermediate (indium-Oxalate Salt), re-crystallization and its thermal decomposition. The waste ITO targets were generated from vacuum sputtering process. The effects of operating parameters, such as solid dosage, oxalic acid concentration, reaction temperature and time, on the precipitation and re-crystallization of indium-Oxalate Salt were examined. Thermal decomposition to indium oxide was also investigated. The optimum reaction conditions to indium-Oxalate Salt were oxalic acid concentration 1.5 M, solid dosage 50 g/L, reaction temperature 80 °C and reaction time 8 hours. The purity of indium-Oxalate Salt prepared by precipitation and re-crystallization was 99.99% (4 N), and the Salts were thermally decomposed to indium oxide at over 600 oC. The purity of the final product, indium oxide, was dependent on that of the intermediate, indium Oxalate Salt.
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Preparation of indium tin oxide powder from low-grade metallic indium and tin
Korean Journal of Chemical Engineering, 2016Co-Authors: Changsik JuAbstract:Preparation of indium-tin oxide(ITO) powder by oxalic acid from metallic indium and tin was investigated. The intermediate(indium-tin Oxalate Salt) was formerly prepared at various conditions, and thermal decomposition was followed to obtain ITO powder for ITO target. Optimum conditions for preparation of the intermediate were oxalic acid concentration 2.0 M, pH 8.0, reaction temperature 80 °C and reaction time 6 hours. The purity of the intermediate could be increased by recrystallization up to 99.99% (4 N). The phase transition temperature of the intermediate to ITO powder was analyzed by TGA. The purity, crystal structure and particle shape of ITO powder were examined by ICP-OES, XRD and TEM, respectively. ITO powder obtained was spherical, whose size was 20–50 nm.
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preparation of high purity indium Oxalate Salt from indium scrap by organic acids
Korean Journal of Chemical Engineering, 2013Co-Authors: Changsik JuAbstract:Effect of organic acid on the preparation of indium-Oxalate Salt from indium scraps generated from ITO glass manufacturing process was studied. Effects of parameters, such as type and concentration of organic acids, pH of reactant, temperature, reaction time on indium-Oxalate Salt preparation were examined. The impurity removal efficiency was similar for both oxalic acid and citric acid, but citric acid did not make organic acid Salt with indium. The optimum conditions were 1.5 M oxalic acid, pH 7, , and 6 hours. On the other hand, the recoveries increased with pH, but the purity decreased. The indium-Oxalate Salt purity prepared by two cycles was 99.995% (4N5). The indium-Oxalate Salt could be converted to indium oxide and indium metal by substitution reaction and calcination.
