Solvent-Free Green Synthesis of Azines and Their Conversion to 2,5-Disubstituted-1,3,4-thiadiazoles

A solvent-free, clean, and efficient method has been developed for the synthesis of 2,5-disubstituted-1,3,4-thiadiazoles via azines. This approach exploits the synthetic potential of clean reactions and offers many advantages such as excellent product yields, easy isolation of products, and ecofriendly benign reaction conditions. The newly synthesized compounds were analyzed by infrared, ¹H NMR, ¹³C NMR, and elemental analysis.     

High Temperature Corrosion Resistance of Coatings Deposited by Hvof for Application in Steam Turbines

The geothermal steam turbines are exposed to mechanisms of corrosion/erosion that weakens its components and reduces their useful life. Due to this problem work has been done in application and characterization of coating in solid state by means of the technique of high-velocity Oxygen Fuel (HVOF), evaluating the corrosion rate (V_corr) at high temperature of MCrAlY and Diamalloy 4006 coatings deposited on stainless steel SS304. Test was performance in an Autoclave at 170 ⁰C using a modified geothermal fluid as electrolyte. Open circuit potential was monitoring during 24 hours until the system reached the equilibrium. After that, Polarization and Impedance Spectroscopy techniques were used to evaluate the specimens. For microstructure characterization; X–ray Diffraction (XRD), electron sweep microscope (SEM) and Optical microscope were applied. Results show that both coatings (Diamalloy 4006 and MCrAlY), have low current density compare with the substrate, which is an indicative of a lower corrosion rate due to the passive behavior of the species deposited on the Surface of the coating.     

类椭球氧化锌纳米结构的制备与表征

"用普通氧化锌晶须作为原材料, 采用高压釜腐蚀法和高温(600 ℃)裂解结合的方法合成纳米棒构成的氧化锌类椭球结构．XRD、SEM和TEM结果表明这种类椭球结构是单晶的,纳米棒取向一致,自组装生长而成．"     

Determination of total phosphorus and nitrogen in turbid waters by oxidation with alkaline potassium peroxodisulfate and low pressure microwave digestion, autoclave heating or the use of closed vessels in a hot water bath: comparison with Kjeldahl digestion

The evaluation of the use of alkaline peroxodisulfate digestion with low pressure microwave, autoclave or hot water bath heating for the determination of total phosphorus and nitrogen in turbid lake and river waters is described. The efficiency of these digestion procedures were compared to a Kjeldahl digestion procedure with sulphuric acid-potassium sulfate and copper sulfate. The final solution before digestion was 0.045 M in potassium peroxodisulfate and 0.04 M in sodium hydroxide. Procedures were evaluated by the analysis of suspensions of two reference materials, National Institute of Environmental Science, Japan, no. 3 Chlorella and no. 2 pond sediment and natural turbid waters. Best recoveries of phosphorus and nitrogen by microwave heating were obtained when solutions were digested at 95 °C for 40 min. Quantitative recoveries of phosphorus from Chlorella suspensions up to 1000 mg/l were obtained by all three heating procedures, but incomplete recoveries of nitrogen occurred above 20 mg N/l in the digested sample. Good recoveries of phosphorus and nitrogen from suspended sediment suspensions were obtained only from solutions containing <150 mg/l of suspended sediments. Recoveries of phosphorus from phosphorus compounds containing COP and CP bonds added to distilled water were quantitative (94-113%) except for polyphosphates (microwave, 34±8; autoclave, 114±6; water bath, 96±4) and aluminium phosphate (8-23%). Recoveries of nitrogen compounds containing CN bonds added to distilled water were quantitative (94-96%). The analysis of a range of natural turbid water samples by alkaline peroxodisulfate and microwave, autoclave and water bath heating gave similar total phosphorus and nitrogen results. All procedures using alkaline peroxodisulfate underestimate phosphorus concentrations at high suspended sediment concentrations (>150 mg/l) and are only suitable for the analysis of very turbid samples when the turbidity is due to organic matter (algal cells, plant detritus). Underestimation of nitrogen occurs when samples contain more than 20 mg N/l.     

Dissolution of sintered thorium dioxide in phosphoric acid using autoclave and microwave methods with detection by gamma spectrometry

A quantitative and fast method of dissolution of refractory thoria (ThO₂) was developed for the determination of thorium (Th) in a given sample. The dissolution of sintered ThO₂ powder, microspheres and pellets using 88% phosphoric acid was investigated. The conditions of quantitative dissolution of ThO₂ microspheres were optimized by conventional heating in autoclave and also by microwave heating. 100 mg of sintered ThO₂ microspheres were dissolved in 8 g of phosphoric acid in an autoclave, and heating at 170 °C for 3 h, in comparison to 5 g of phosphoric acid by microwave heating (375 W) at 220 °C for 1 h. Dissolution studies on the powder form of sintered ThO₂ were also performed. 1 g of sintered ThO₂ powder could be dissolved in 6.5 g of phosphoric acid in autoclave heating at 170 °C for 1 h. Strong complexing of (PO₄)³⁻ with Th⁴⁺ may be the influencing factor for quantitative dissolution of ThO₂.     

Use of HPHT Autoclave to Determine Corrosion Inhibition Effect of Poly（methyl methacrylate-co-N-vinyl-2-pyrrolidone） on Carbon Steels in 3.5% NaCl Solution Saturated with CO2

The influence of poly(methylmethacrylate-co-N-vinyl-2-pyrrolidone), P(MMA-co-VP), on corrosion of carbon steels(J55, N80, P110 SS and C110 steels) in 3.5 wt% NaCl solution saturated with CO2 was evaluated using static high pressure and high temperature(HPHT) autoclave. The surface was further evaluated by X-ray diffraction(XRD), scanning electron microscopy(SEM) and contact angle measurements. Quantum chemical calculations have been used to evaluate the structural, electronic and reactivity parameters of the inhibitor on the steels surface. SEM, XRD and contact angle measurement studies reveal that the surface of metals are quite unaffected after use of inhibitor in 3.5% NaCl solution saturated with CO2.     

Hydrothermal synthesis of large maghemite nanoparticles: influence of the pH on the particle size

Maghemite nanoparticles with sizes in the range 10–110 nm and good monodispersity have been synthesized by co precipitation at room temperature from Fe²⁺ and Fe³⁺ ions by a (N(CH₃)₄OH) solution, followed by an hydrothermal treatment at 200 °C and an oxidation step with Fe(NO₃)₃. The influence of the incubation time (at 200 °C) and of the pH of the autoclaved solution on the particles size has been studied. It was found that the pH value allows to tune the size of the maghemite particles. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

玉米秸秆常压催化液化及产物分析

以玉米秸秆粉末为原料,浓磷酸为反应催化剂,选取多种有机溶剂为液化剂,170 ℃的条件下,在高压反应釜中制备秸秆生物质油。考察了三乙酸甘油酯复配碳酸乙烯酯、甘油复配碳酸乙烯酯以及聚乙二醇复配碳酸乙烯酯(均为6∶1ω/ω)三种不同的混合液化剂对液化得率和生物质油产品性能的影响。采用气质联用仪(GC-MS)分析秸秆生物质油的化学组成;傅里叶红外光谱仪(FTIR)分析原料和液化残渣的主要官能团。实验结果表明聚乙二醇与碳酸乙烯酯混合溶剂液化时,秸秆生物质油得率为97.84%,三乙酸甘油酯与碳酸乙烯酯混合液化时得率为80.20%,甘油与碳酸乙烯酯混合液化时得率为36.97%。FTIR分析结果表明,以聚乙二醇与碳酸乙烯酯混合溶剂为液化剂,秸秆中纤维素、半纤维素和木素的特征官能团几乎全部消失,液化效果最好。GC-MS分析结果表明,生物质油的成分复杂,主要包括有机酸和酮类、醇和醚类、芳香类、糖类和酯类等化合物。     

Influence of molar mass distribution and long-chain branching on strain hardening of low density polyethylene

Low-density polyethylenes (LDPE) were synthesized in a laboratory-scale autoclave under high pressure. These samples were found to possess a high molar mass tail, resulting in a distinctly bimodal molar mass distribution and a lower concentration of long-chain branching than typical of commercial LDPEs. Rheological experiments in elongation showed that these samples exhibit a very pronounced strain hardening, which could be favorable for distinct processing operations. Although the samples have a rather high molar mass ( g/mol), their zero shear-rate viscosities η ₀ and their shear thinning behavior are still in a range, where thermoplastic processing is possible. A qualitative understanding of the experimental results is tried by the model of the Cayley tree.

Synthesis,characterization and significant antimicrobial properties of CZTS nanoparticles against pathogenic strains

Antibacterial properties have wide application in water disinfection, textile industry, medicine, and food packaging. The present work focuses on the efficacy of Cu₂ZnSnS₄ (CZTS) nanoparticles as a possible promising antibacterial agent along those directions. CZTS nanomaterials were synthesized following the solvo-thermal method using Teflon-lined stainless-steel autoclave. Nanoparticles were characterized using XRD, Raman spectroscopy, UV–visible spectroscopy, and SEM techniques. SEM shows that the size of synthesized nanoparticle was 50-100 ?nm. Antibacterial activity of CZTS nanoparticles was performed against ten pathogenic bacterial strains, which include 5 Gram-positive strains (viz. Staphylococcus epidermidis, Bacillus megaterium, Mycobacterium smegmatis, Lactobacillus and Staphylococcus aureus) and 5 Gram-negative strains (viz. Serratia marcescense, Salmonella typhi, Escherichia coli, Proteus vulgaris and Pseudomonas aeruginosa), using the well diffusion method. CZTS nanoparticles shows significant antibacterial activity against both the Gram-positive and Gram-negative bacterial strains. Notable increase in the antibacterial activity of CZTS nanoparticles has been observed with the increase in the concentration of nanoparticles in terms of zone of inhibition (ZOI), which helps us to study the cell toxicity. Minimum inhibitory concentration (MIC) has been observed with the lowest concentration of nanoparticles that show visible growth of bacteria, which certainly may contribute significantly toward possible medicinal applications of CZTS nanoparticles.