Sharif Digital Repository

Ultra-small and highly dispersive (< 10 nm) iron oxide hydroxide is characterized by some methods. The compound is an efficient and stable catalyst for alcohol oxidation, organic sulfide oxidation, and epoxidation of alkenes in the presence of H2O2. The electrochemical oxygen-evolution reaction of the iron oxide hydroxide is also tested under acidic, neutral, and alkaline conditions. In the presence of the iron oxide hydroxide, excellent conversions (75–100%) and selectivities of substrates (92–97%), depending on the nature of the sulfide, were obtained. Benzylalcohols having electron-donating and-withdrawing substituents in the aromatic ring were oxidized to produce the corresponding... 

A mixture of Ni(II) and Fe(II) supported on Dowex 50W catalyses Baeyer- Villiger oxidation of ketones using molecular oxygen and benzaldehyde  

Monomer grafting, a unique technique for polysaccharide modification, is always performed under inert (e.g., N2) atmosphere. This work is the first report related to evaluating the possibility and efficiency of the grafting of acrylonitrile (AN) onto starch in presence of oxygen. Thus, corn starch (in both granular and gelatinized states) as well as soluble starch were grafted by AN using a ceric-carbohydrate redox initiating system. Graft copolymerizations were performed under nitrogen, air, and oxygen atmospheres at similar conditions. Grafting occurrence was verified using chemical and spectral proofs. The polymerization mechanism and kinetics were investigated by recording the... 

Acrylonitrile (AN) was grafted onto various natural and modified polysaccharides (i.e., gum arabic, gum tragacanth, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) by using ceric-carbohydrate redox initiating system. After overcoming practical problems, mainly from the high viscosity of the aqueous solutions of the different substrates, the graft copolymerization reactions were run either in air or in N2 atmosphere under similar conditions. Grafting was confirmed using chemical and spectral (FTIR) proofs. The reactions were kinetically investigated using semi-empirical expressions and time-temperature profiles. An anomalous... 

Oxy-fuel firing is more energy efficient and environmental friendly than conventional air-fuel firing and its application to reheating furnaces has hegun since 1990s. A computational method was presented to predict the steady heat transfer to the billets and temperature distribution in a continuous pusher type reheating furnace in which combustion air was enhanced by oxygen. Radiation heat flux calculated from the radiation heat exchange within the furnace was modeled using the FVM considering the effects of furnace walls and billets. Energy consumption per ton of steel, production rate and thermal efficiency of furnace, and trend of NOx emission in various levels of oxygen enrichment were... 

Montmorillonite K10-supported manganese(II) chloride was found to be an efficient and convenient catalyst for the oxidative cleavage of oximes, phenylhydrazones and semicarbazones to the corresponding carbonyl compounds with molecular oxygen. © 2006 Bentham Science Publishers Ltd  

Oxidation of aromatic alcohols to corresponding aldehydes and ketones have been carried out using molecular oxygen and FeCl3 supported on kieselguhr as catalyst in good yields. © 2005 Bentham Science Publishers Ltd  

A 1:1 molar ratio of the cobalt and manganese salts of p-amino benzoic acid supported on silica gel is an effective catalyst for the oxidation of various organic compounds in reasonable yields using molecular oxygen. The catalyst can be reused several times  

Gd(Ba2-xPrx)Cu3O7+δ single phase polycrystalline samples with 0.0 < − x < − 1.0 were investigated for their structural and electronic properties. Due to the solubility limit, the 123 structure forms in the 0.0 < − x < −0.50 range; for x > −0.6, a decomposition of the perovskite-type phases occurs. For x=0.2, there is an orthorhombic-tetragonal phase transition, concurrent with a metal-insulator transition, which is evident in the normal state resistivity. For xc=0.35, the superconductor-insulator transition occurs. An unusual hump has been observed on the resistivity vs temperature curve of the samples for particular values of Pr doping. Based on the Rietveld refinement of the x-ray... 

Acrylonitrile (AN) was grafted onto various natural and modified polysaccharides (i.e., gum arabic, gum tragacanth, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) by using ceric-carbohydrate redox initiating system. After overcoming practical problems, mainly from the high viscosity of the aqueous solutions of the different substrates, the graft copolymerization reactions were run either in air or in N2 atmosphere under similar conditions. Grafting was confirmed using chemical and spectral (FTIR) proofs. The reactions were kinetically investigated using semi-empirical expressions and time-temperature profiles. An anomalous... 

Monomer grafting, a unique technique for polysaccharide modification, is always performed under inert (e.g., N2) atmosphere. This work is the first report related to evaluating the possibility and efficiency of the grafting of acrylonitrile (AN) onto starch in presence of oxygen. Thus, corn starch (in both granular and gelatinized states) as well as soluble starch were grafted by AN using a ceric-carbohydrate redox initiating system. Graft copolymerizations were performed under nitrogen, air, and oxygen atmospheres at similar conditions. Grafting occurrence was verified using chemical and spectral proofs. The polymerization mechanism and kinetics were investigated by recording the... 

The title complex [Mn(tptz)(CH3COO)(OH2) 2]NO3 was synthesized through the reaction of tptz (2,4,6-tris(2-pyridyl)-1,3,5-triazine), nitric acid and manganese(II) acetate. The molecular structure was characterized by X-ray diffraction, elemental analysis, electrochemistry, EPR, IR, fluorescence and UV-Vis spectroscopy and its oxygen evolving activity has been studied. X-ray structure analysis shows that each Mn(II) ion is seven coordinated by a bidentate acetate, three nitrogen atoms of tptz and two oxygen atoms from two water ligands, which are coordinated in axial positions. The complex acts as an oxygen evolving complex with oxone (2KHSO5·KHSO4·K 2SO4) as primary oxidant in aqueous... 

A dense membrane of La0.6Sr0.4Co0.8Fe0.2O3- δ (LSCF) perovskite was prepared by a new chelating agent, ethylene diamine N,N,N′,N′-tetra N-acetyl diamine (EDTNAD). As a potent ligand, EDTNAD provided a facile one-step method to form complexes of the four metal ions, simultaneously. The oxygen permeation flux through the pure perovskite LSCF dense membrane was measured over temperature range of 1073-1223 K, thickness of 0.7-1.0 mm and oxygen partial pressure of 0.1-1.0 bar. Oxidative coupling of methane (OCM) reaction using LSCF disk in the atmospheric membrane reactor and over the temperature range of 1073-1173 K showed a C2 selectivity of 100% and C2 yield of 5.01% at 1153 K. Furthermore,... 

Three dense membranes of types SrCo0.8Fe0.2O 3-δ (SCF(82)), La0.6Sr0.4Co 0.8Fe0.2O3-δ (LSCF(6482)) and La 0.8Sr0.2Co0.6Fe0.4O 3-δ (LSCF(8264)) perovskites were prepared by complexation applying a chelating agent, ethylene diamine N,N,N′,N′-tetra-N- acetyl-diamine (EDTNAD). The oxygen permeation flux through the perovskite membranes was measured as a function of temperature within 1,073-1,223 K as well as the oxygen partial pressure of 0.1-1.0 bar. The oxygen permeation fluxes for the membranes, SCF(82), LSCF(6482), LSCF(8264) with the thickness of 0.85 mm were observed as 9.2×10-7 (mol/cm2 s), 1.7×10-7 (mol/cm2 s), and 1.0×10-7 (mol/cm2 s) in these cases at 1,153 K. The results indicated the... 

For the first time, the effect of calcination process on characteristics and catalytic performances of Pd supported on different MOFs (MIL-101(Cr), NH2-MIL-101(Cr), and HKUST-1) was evaluated. Besides, the various orders of calcination process and reduction one on Pd/MOF and Pd/calcinated-MOF were studied, and their performances in CO oxidation reaction were presented to find the effect of H2 and O2. Results showed that the effect of calcination and reduction processes on the catalytic activities and characteristics strongly depends on the nature of MOF. Among MIL-based catalysts, the catalyst with no calcination treatment showed the best activity. Among MNH2-based catalysts, high activity... 

The coronavirus disease (COVID-19) pandemic, which has spread around the world, caused the death of many affected patients, partly because of the lack of oxygen arising from impaired respiration or blood circulation. Thus, maintaining an appropriate level of oxygen in the patients' blood by devising alternatives to ventilator systems is a top priority goal for clinicians. The present review highlights the ever-increasing application of nanobubbles (NBs), miniature gaseous vesicles, for the oxygenation of hypoxic patients. Oxygen-containing NBs can exert a range of beneficial physiologic and pharmacologic effects that include tissue oxygenation, as well as tissue repair mechanisms,... 

For the first time, the effect of calcination process on characteristics and catalytic performances of Pd supported on different MOFs (MIL-101(Cr), NH2-MIL-101(Cr), and HKUST-1) was evaluated. Besides, the various orders of calcination process and reduction one on Pd/MOF and Pd/calcinated-MOF were studied, and their performances in CO oxidation reaction were presented to find the effect of H2 and O2. Results showed that the effect of calcination and reduction processes on the catalytic activities and characteristics strongly depends on the nature of MOF. Among MIL-based catalysts, the catalyst with no calcination treatment showed the best activity. Among MNH2-based catalysts, high activity... 

The coronavirus disease (COVID-19) pandemic, which has spread around the world, caused the death of many affected patients, partly because of the lack of oxygen arising from impaired respiration or blood circulation. Thus, maintaining an appropriate level of oxygen in the patients' blood by devising alternatives to ventilator systems is a top priority goal for clinicians. The present review highlights the ever-increasing application of nanobubbles (NBs), miniature gaseous vesicles, for the oxygenation of hypoxic patients. Oxygen-containing NBs can exert a range of beneficial physiologic and pharmacologic effects that include tissue oxygenation, as well as tissue repair mechanisms,... 

A reduction in catalyst activity with time-on-stream and formation of side products are the major problems associated with catalytic propane dehydrogenation. Coke formation on the catalyst surface is the most important cause for catalyst deactivation. Experiments have indicated that the presence of very small amounts of oxygenated additives such as water can reduce the amount of coke accumulated on the catalyst surface and enhance catalyst activity. Addition of water beyond an optimum level, however, would result in a loss of activity due to sintering of catalyst. Propane dehydrogenation over a Pt-Sn/γ-Al2O3 catalyst in the temperature range of 575 to 620 °C was investigated in the presence... 

A tanks-in-series model was applied for mathematical modeling of the unsteady state performance of 70 and 100 liters airlift bioreactor for the production of lactic acid by fermentation. A set of first-order differential equations for the material balances of micro-organism, substrate, product, and dissolved oxygen around hypothetically well mixed stages was solved simultaneously utilizing computer program in MATLAB. The kinetic model utilized considered the effect of two substrates (glucose and dissolved oxygen) on the growth rate. The effect of air velocity on the lactic acid production was investigated. Results of this model have been validated with experimental data