Recovery of Nitric Acid To Obtain a Gypsum Binder

The possibility of processing nitric acid leaching solutions to obtain recovered nitric acid and gypsum with good binding properties was studied in order to develop a new technology for processing of the sphene concentrate.     

Methods for Concentration of Hydrogen Peroxide To Obtain It in Anhydrous Form

Methods for concentrating hydrogen peroxide and obtaining this compound in anhydrous form, based on removal or binding of water from the surface of solution in an open vessel or in a closed volume and also on binding of water directly in a H₂O₂ solution, are described.     

Modification of Natural Shungites To Obtain a Mixed Nanocarbon Material (MNS)

An original technology for processing of a natural material, shungite-3 from the Zazhogino deposit (Karelia), was developed in order to obtain a new product, mixed nanocarbon material (MNS).__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 6, 2005, pp. 887–890.Original Russian Text Copyright © 2005 by Charykov, Alekseev, Arapov, Alekhin, Gerasimov, Nekrasov, Polekhovskii, Semenov.     

Self‐Reporting Inhibitors: A Single Crystallization Process To Obtain Two Optically Pure Enantiomers

Collection of two optically pure enantiomers in a single crystallization process can significantly increase the chiral separation efficiency but this is difficult to realize. Now a self‐reporting strategy is presented for visualizing the crystallization process by a dyed self‐assembled inhibitor made from the copolymers with tri(ethylene glycol)‐grafting polymethylsiloxane as the main chain and poly(N⁶‐methacryloyl‐l ‐lysine) as side chains. When applied with seeds together for the fractional crystallization of conglomerates, the inhibitors can label the formation of the secondary crystals and guide the complete separation process of two enantiomers with colorless crystals as the first product and red crystals as the second. This method leads to high optical purity of d /l ‐Asn?H₂O (99.9 % ee for d ‐crystals and 99.5 % for l ‐crystals) in a single crystallization process. It requires a small amount of additives and shows excellent recyclability.     

A Bulk Resin Bead Procedure To Obtain Uranium And Plutonium From Radioactive Solutions For Mass Spectrometric Analysis

Abstract

A method is described for extracting representative uranium and plutonium samples from highly radioactive solutions for isotopic mass spectrometric analysis. Anion resin beads in the nitrate form are used to effect separation from fission products and other actinides. Conditions required to achieve separation are proper adjustment of the uranium and nitric acid concentrations. Once uranium and plutonium are adsorbed, each bead serves as a sample for mass spectrometric analysis, with plutonium and uranium being run sequentially from the same bead. Quantitative determination of the two elements is effected through the technique of isotopic dilution.     

Technologies for Processing of Crude Glycerol from Biodiesel Production: Synthesis of Solketal and Its Hydrolysis to Obtain Pure Glycerol

Information on the volume of production of biodiesel and crude glycerol from it is analyzed. The possibility of using crude glycerol as a feedstock for preparing solketal is demonstrated. The specific features of the solketal synthesis from crude glycerol and of separation of the reaction products are described. A catalytic process is suggested for selective decomposition of solketal to glycerol to obtain purified glycerol of any required concentration up to 99.8 wt %. A flowsheet is suggested for processing of crude glycerol to obtain solketal and subsequently converting it to obtain pure glycerol.     

Applying the Retro‐Enantio Approach To Obtain a Peptide Capable of Overcoming the Blood–Brain Barrier

The blood–brain barrier (BBB) is a formidable physical and enzymatic barrier that tightly controls the passage of molecules from the blood to the brain. In fact, less than 2 % of all potential neurotherapeutics are able to cross it. Here, by applying the retro‐enantio approach to a peptide that targets the transferrin receptor, a full protease‐resistant peptide with the capacity to act as a BBB shuttle was obtained and thus enabled the transport of a variety of cargos into the central nervous system.     

Sulfur-Free Vulcanization of Modified Butadiene-Acrylonitrile Rubber SKN-40PVKh-30, Aimed To Obtain Elastomeric Materials Resistant to Aggressive Media

A study was made of the thermal, peroxide, and radiation vulcanization of modified butadiene-acrylonitrile rubber SKN-40PVKh-30 in the presence of a polyhalomethyl compound, 1,4-bis[(4-trichloromethylphenyl)dichloromethyl]benzene, with epoxy and phenol-formaldehyde resins and 4,4′-dithiobis-N-phenylmaleimide (a sensitizer) additionally included in the formulation with the aim to improve the technical properties of the vulcanizates and elastomeric materials. The parameters of the three-dimensional network of the vulcanizates were studied by sol-gel analysis; the total number of active chains of the network (1/M_c), number of cross-linked molecules \((1/M_{n_\tau } )\), and gel fraction content were determined for the thermal, peroxide, radiation, and thermoradiation vulcanizates.     

氯化镁/聚乙二醇复配增塑剂热塑加工聚乙烯醇

采用氯化镁和聚乙二醇对聚乙烯醇(PVA)进行增塑改性, 并利用熔融加工方法制备了PVA薄膜.采用傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、差示扫描量热分析(DSC)和热重分析(TGA)方法研究了由氯化镁和聚乙二醇组成的复配增塑剂与PVA的相互作用及复配增塑剂对PVA结晶性能、热性能和力学性能的影响.结果表明, 由氯化镁和聚乙二醇组成的复配增塑剂能有效地破坏PVA自身的氢键, 降低PVA的结晶度和熔融温度, 提高PVA的热稳定性并扩展PVA的热塑加工温度窗口.由复配增塑剂通过热塑加工方法制得的PVA薄膜具有较好的力学性能, 拉伸强度为31 MPa, 断裂伸长率为466%.     

Optimization of the Pyrolysis of Naphtha Fractions of the West Siberian Gas Condensate to Obtain Lower Olefins and Divinyl

Russian Journal of Applied Chemistry - Naphtha fractions of the West Siberian gas condensate were evaluated as feedstock for thermal pyrolysis performed in the temperature interval...     

Selective Etching of Silicon from Ti3SiC2 (MAX) To Obtain 2D Titanium Carbide (MXene)

Until now, MXenes could only be produced from MAX phases containing aluminum, such as Ti₃AlC₂. Here, we report on the synthesis of Ti₃C₂ (MXene) through selective etching of silicon from titanium silicon carbide—the most common MAX phase. Liters of colloidal solutions of delaminated Ti₃SiC₂‐derived MXene (0.5–1.3 mg mL^?1) were produced and processed into flexible and electrically conductive films, which show higher oxidation resistance than MXene synthesized from Ti₃AlC₂. This new synthesis method greatly widens the range of precursors for MXene synthesis.     

Multiobjective Optimization of Industrial Petroleum Processing Units Using Genetic Algorithms

For many years most of refining processes were optimized using single objective approach, but practically such complex processes must be optimized with several objectives. Multiobjective optimization allows taking all of desired objectives directly and provide search of optimal solution with respect to all of them. Genetic algorithms proved themselves as a powerful and robust tool for multi-objective optimization. In this article, the review for a last decade of multi-objective optimization cases is provided. Most popular genetic algorithms and techniques are mentioned. From a practical point it is shown which objectives are usually chosen for optimization, what constraint and limitations might impose multi-objective optimization problem formulation. Different types of petroleum refining processes are considered such as catalytic and thermal.     

Optimization of an Extraction Process to Obtain a Food-Grade Sulforaphane-Rich Extract from Broccoli (Brassica oleracea var. italica)

Sulforaphane (SFN) is a powerful health-promoting compound found in broccoli in the form of its inactive precursor, glucoraphanin (GFN). SFN formation occurs through the enzymatic hydrolysis of glucoraphanin by myrosinase under specific chemical conditions. Its incorporation in food formulations has been hindered by the thermal instability of SFN and low concentration in Brassicaceae. Then, extracting SFN from broccoli at a temperature below 40 °C appears as an option to recover and stabilize SFN, aiming at delivering it as a nutraceutical. We studied an eco-friendly extraction process to obtain an SFN-rich extract from broccoli. The effect of the broccoli mass/solvent ratio, ethanol concentration in the extractant solution, and extraction time on the recovery of SFN, GFN, phenolic compounds, and antioxidant activity were studied through a Box–Behnken design. The regression models explained more than 70% of the variability in the responses, adequately representing the system. The experimental factors differently affected the bioactive compound recovery and antioxidant activity of the extracts. The extraction conditions that allowed the highest recovery of bioactive compounds and antioxidant activity were identified and experimentally validated. The results may provide the basis for the design of a process to produce a sulforaphane-rich food supplement or nutraceutical by using a GRAS extractant.     

Preparation and Characterization of Novel Ti-doped M-site Deficient Olivine LiFePO4

Phospho-olivine LiFePO4 as a promising cathode material for lithium ion batteries has aroused considerable interest due to its low cost, benign for environment, high temperature capability and relatively high energy density1,2. The main drawback of LiFePO…     

微米橄榄石型LiFePO4的水热合成优化

为深入研究大颗粒磷酸铁锂(LiFePO₄)锂离子电池正极材料的性能衰退机理并据此改善其体积能量密度和功率密度, 进而切实推进该材料在电动汽车、混合动力汽车和电站储能等领域的高效广泛应用, 本文通过优化水热合成条件制备了粒径为2 μm的均匀微米LiFePO₄颗粒粉末. 在未经任何改性(包覆或掺杂)的情况下,该材料表现出本征大颗粒LiFePO₄典型的充放电和循环性能, 可作为后续研究的代表样品进一步考察大颗粒材料相对纳米材料性能衰退的机制和根本原因, 最终通过有的放矢地改性手段获得高密度、高能量和高功率的LiFePO₄ 正极材料. 实验结果表明, 增加反应物浓度、水热温度和保温时间以及降低溶液pH 值均有利于LiFePO₄颗粒的长大. 通过比较不同粒径的LiFePO₄的电化学性能确证了其随颗粒尺寸的增大而衰退. 当颗粒大小由0.7 μm增加到16.5 μm时, LiFePO₄在0.1C倍率下的放电比容量由152 mAh·g^-1下降至80 mAh·g^-1.同时, 1C倍率下的循环测试结果表明, 颗粒尺寸越大, LiFePO₄的容量衰减愈严重.     

橄榄石LiFePO4复合正极材料的合成及其电化学性能研究

采用固相反应法在惰性气氛中合成了橄榄石型LiFePO₄/C复合正极材料,考察了焙烧温度对目标材料性能的影响.采用XRD、SEM、TG-DSC、激光粒度分布以及电化学测试等手段对该材料进行了结构表征和性能测试.结果表明,完美的结晶、较小的粒径以及与导电剂的良好接触是产物具有优良电化学性能的保证.于750℃下制得产物的结构完整,表面形貌较好,粒经分布均匀,具有良好的电化学性能.在室温及0.05 C充放电倍率下,该材料的首次放电容量为142.5 mA.h/g,循环50次后,未见明显衰减.     

Chemical Functionalisation of Vinyl Polymers to Obtain Heparin-Like Materials

Vinyl polymers such as poly(ethylene-co-vinyl alcohol) (EVAL) and polyallylamine (PALA) both commercially available were chemically modified by introduction of carboxylic and sulfonate groups to obtain polymeric materials with improved haemocompatibility. The introduction of carboxyl groups was carried out by reaction of EVAL's hydroxy groups with acrylonitrile followed by basic hydrolysis of  CN groups. Amino groups of PALA were transformed into sulfonate groups by reaction with pyridine-SO₃ complex. Influence of reagents molar ratio, temperature and reaction time on the carboxylation degree was evaluated. In particular, yields of 86% (EVAL-CN 0.52) and 30% (EVALCOOH 0.16) were obtained for the cyanoethylation and the hydrolysis reaction of the  CN groups, respectively, whereas a sulfonation of 24% of the PALA amino groups was found. The functionalised polymers were characterized by physicochemical measurements. Preliminary biological tests proved the importance of strong acidic groups on the anticoagulant properties of the polymeric materials.     

电感耦合等离子体原子发射光谱法测定镁及镁合金中硅含量

用硝酸及少量氢氟酸可将试样完全溶解,所得溶液可用于电感耦合等离子体原子发射光谱法(ICP-AES)或钼蓝分光光度法测定镁和镁合金中的硅含量,对ICP-AES测定硅的分析条件作了试验.为避免各共存元素的干扰,方法中选择波长为Si Ⅰ 251.611 nm及Si Ⅰ 212.412 nm的谱线作为分析谱线.在制作工作曲线时加入与待测样品等量的镁以补偿基体组分引起的基体效应,在选用上述两谱线作为分析线时,硅的质量浓度在40.0 mg·L-1以内时与谱线的发射强度均呈线性关系,所得检出限(3S/N)依次为6.2和15μg·L-1.应用此方法分析了3种镁合金标准样品,所得结果与标准值相符.     

The Role of Processing Solvent on Morphology Optimization for Slot-Die Printed Organic Photovoltaics

Chinese Journal of Polymer Science - The morphology manipulation of the active layers is important for improving the performance of organic photovoltaics (OPVs). The choice of processing solvent...