Sr4AlNbO8: A new crystal structure type determined from powder X-ray data

Sr₄AlNbO₈ was synthesized at 1500 °C in air. The crystal structure was initially determined from powder X-ray diffraction data, and later refined with combined X-ray and neutron diffraction data (P2₁/c; a=7.17592(2) Å, b=5.80261(2) Å, c=19.7408(1) Å; β=97.5470(1)°, V=814.869(3) Å³, Z=4, R_p/R_wp=10.04%/13.18% for X-ray data, 4.40%/5.67% for neutron data, and 7.71%/10.74% in total with χ² of 3.76, 23 °C). The crystal structure is a new structure type and may be described as a three-dimensional polyhedral network resulting from the corner-sharing of NbO₆ and Sr1O₆ octahedra and AlO₄ tetrahedra. Also, the other strontium atoms (Sr2, Sr3, and Sr4) occupy the larger cavities surrounded by oxygen atoms to form nine, eight, and 11 coordination, respectively. Considering that Sr, Al, and Nb atoms are crystallographically distinct in terms of interatomic distances and polyhedral coordination, Sr₄AlNbO₈ can be regarded as a stoichiometric compound.     

Chiolite-like Ca5Te3O14: An X-ray and neutron diffraction study

The crystal structure of Ca₅Te₃O₁₄ at room temperature was studied by the Rietveld method using combined X-ray and neutron powder diffraction data. The compound crystallizes in the space group Cmca with the lattice parameters a=10.4268(2) Å, b=10.3908(2) Å and c=10.4702(2) Å. The structure of Ca₅Te₃O₁₄ is chiolite-like and consists of a framework of corner-linked TeO₆ octahedral layers in which a linear TeO₂ group of every fourth octahedron is substituted by a Ca atom. This type of structure was previously observed in BaSr₄U₃O₁₄. The relationship between the chiolite-like structure and the fluorite structure is discussed.     

毛细管电泳检测奶粉中添加的大豆分离蛋白

采用毛细管电泳方法对乳蛋白和大豆分离蛋白进行检测。选择聚丙烯酰胺涂层毛细管,在紫外检测波长214 nm、分离电压25 kV条件下测出五种乳蛋白在不同线性范围内的线性相关系数均大于0.998,各乳蛋白的迁移时间和峰面积的相对标准偏差(RSD)分别小于0.34%和4.50%,奶粉样品加标回收率范围为88.07%~102%;通过对比大豆7S和11S组分、大豆分离蛋白及乳蛋白的电泳图谱,定性确定出大豆分离蛋白8个特征峰,各特征峰的迁移时间和峰面积的RSD分别小于0.36%和4.87%,方法重现性较好。建立了奶粉中添加大豆分离蛋白的半定量检测方法。     

Bioanalytical Application of the Ordered Mesoporous Carbon Modified Electrodes

An ordered mesoporous carbon modified electrode (OMCE) was prepared by film forming method. The electrochemical behavior of the OMCE was evaluated in connection with the electrochemistry of some electroactive biospecies, such as ascorbic acid (AA), acetaminophenol (AP), cysteine (CySH), dopamine (DA), epinephrine (EP), uric acid (UA), β‐nicotinamide adenine dinucleotide (reduced disodium salt hydrate, NADH), and hydrogen peroxide (H₂O₂) with cyclic voltammetry. Compared with the conventional carbon nanotubes (CNT) and graphite powder (GP) modified electrodes, the OMCE provided the best electrochemical reactivities in all cases associated with decreased over potential, better‐defined peak shape, and higher sensitivity. In addition, the OMC, CNT, and GP modified electrodes were employed as sensitive sensors for H₂O₂ and NADH quantification and as stable platforms for the fabrication of glucose and ethanol biosensors on which the enzymes were immobilized.     

Preparation,spectroscopic, thermal and powder X‐ray diffraction characterization,and antimicrobial activities of mixed bis(O,O′‐diisopropyldithiophosphato‐S,S′)antimony(III) derivatives with some oxygen and sulfur donor ligands

Newly synthesized mixed bis(O,O′‐diisopropyldithiophosphato‐S,S′)antimony(III) derivatives have been characterized using physicochemical, spectral, thermal and powder X‐ray diffraction studies, and their antimicrobial activities were investigated. These derivatives have nanometric crystallite size (11.39–14.67 nm) with unit cell volume (4968.47 and 5079.79 ų) and lower symmetry (monoclinic) crystal system. After thermal decomposition in inert atmosphere, these derivatives give antimony sulfide as a final decomposition product which has many potential applications, and they exhibit enhanced antimicrobial activities (greater zone of inhibition) as compared to the free ligands and standard drugs (chloroamphenicol and terbinafine were used as standard antibacterial and antifungal drugs, respectively) due to the nanometric size of the complexes.     

Oxidative dual C–H sulfenylation: A strategy for the synthesis of bis(imidazo[1,2-a]pyridin-3-yl)sulfanes under metal-free conditions using sulfur powder

An efficient approach to sulfur-bridged imidazopyridines has been developed under metal-free conditions using inexpensive sulfur powder as the sulfur source. Most appealingly, the reaction can proceed smoothly without addition of any additives, ultimately decreasing the production of chemical waste. The inexpensive and green method should provide a useful strategy for constructing a library of novel and biological interesting heteroaromatic sulfides.     

Flow properties and inter-particle forces in fuel powders

This work studied the mechanical properties of a series of industrial fuel powders: bituminite, lignite, and petroleum coke. Sieved cuts of these powders were assessed and the flow properties of each sample were used to calculate tensile strengths as functions of consolidation stress. In addition, BET surface areas and dispersive surface energies were estimated from surface energy analysis. To analyze the bulk flow properties of these fuel powders in terms of micro-contact mechanics, the fundamentals of fuel powder adhesion and consolidation were reconsidered based on the “stiff particles with soft contacts” model proposed by Tomas. In the present work, a multi-contact concept was introduced to account for the irregular shapes of actual particles. This modified model was based on elastic–plastic contact deformation theory and was employed to describe the contact between rough particles and to estimate the associated inter-particle forces. The results were used in conjunction with the Rumpf approach to relate the isostatic tensile strength to the degree of consolidation. Applying average values for the powder compressibility parameters allowed the model to be used for predictive purposes, and an acceptable level of agreement was found between predicted and measured tensile strengths.     

Extraction of humic acid from biological matrix – dry cow dung powder

Abstract

The increased local and global concern, for alarming environmental pollution, offers incentives to explore new green and clean materials and methods for safeguarding the environment. The generation of benign alternate routes for any step in chemical processes, is the need for today and tomorrow. In the present work, humic acid (HA) has been extracted from a green source, “dry cow dung powder”, using simple, cost effective, and eco-friendly methods. HA has been extracted, isolated, and characterized by employing different spectroscopic methods. The process investigated herein imparts a boost to “Green Chemistry”, a promising solution to many global environmental problems.     

Synthesis and characterization of thiosalicylic acid stabilized gold nanoparticles

We report the synthesis of photoluminescent Au nanoparticles of varying sizes stabilized with a carboxylate group terminated aromatic thiol, thiosalicylic acid. The formation of Au nanoparticles and its stabilization with the thiol has been characterized by different spectroscopic and thermal methods. The water solubility, along with the low degree of aggregation and photoluminescence, enhances their suitability for biological applications. The photoluminescence may be due to charge transfer of the Au core with the stabilizing ligand.