Rapid reductive degradation of dye contaminated water by using a core-shell nano zerovalent iron (nZVI)

We report on the synthesis of zero valent iron nano particles (nZVI) via chemical reduction method. The large peak visible in the XRD pattern reveals the presence of an amorphous phase of iron. SEM and TEM images signify the dendritic morphology and core-shell-like structure of manufactured nZVI particles respectively. Methylene blue dye (MB) was used as model contaminant to assess the reductive degradation proficiency of nZVI. With complete elimination of MB, the fresh synthesized nZVI exhibited the best performance (97%), while the regenerated nZVI had an 85.1% MB removal efficiency after five regenerations. The equilibrium data of adsorption were fitted to eight different kinetic and isothermal models. The effects of critical operating factors such as pH, varied amounts of nZVI and dye concentration, adsorption temperature, and adsorption time were also studied. A presumptive reaction mechanism and function of core-shell construction in contaminant sequestration has also been investigated.     

Synthesis and Single Crystal X-ray Studies of 3-(3,5-Bis(trifluoromethyl)phenyl) Quinoline and 3-(4-Fluoro-3-methylphenyl) Quinoline

The title compounds 3-(3,5-bis(trifluoromethyl)phenyl)quinoline(1) and 3-(4-fluoro-3-methylphenyl)quinoline(2) were synthesized through Suzuki-Miyaura Cross coupling reaction of 3-bromoquinoloine with aryl boronic acids.The title compounds were characterized by single-crystal X-ray diffraction,1H NMR,13C NMR,EI-MS,elemental analysis and IR.The crystals of 3-(3,5-bis(trifluoromethyl)phenyl)quinoline(C17H9F6N,Mr = 341.25) belongs to the monoclinic system,space group P21n,a = 12.3072(13),b = 4.9378(6),c = 24.493(2) ,V = 1473.1(3) 3,Z = 4,Dc = 1.539 Mg m-3,λ = 0.71073 ,μ = 0.144 mm-1,F(000) = 688,the final R = 0.0715 and wR = 0.1873 for 1875 observed reflections with I 2σ(I) and the crystal of 3-(4-fluoro-3-methylphenyl)quinoline(C16H12FN,Mr = 237.27) belongs to the orthorhombic system,space group Pca21,a = 23.794(2),b = 3.9094(3),c = 25.669(2) ,V = 2387.7(4) 3,Z = 8,Dc = 1.320 Mg m-3,λ = 0.71073 ,μ = 0.088 mm-1,F(000) = 992,the final R = 0.0534 and wR = 0.1188 for 2270 observed reflections with I 2σ(I).     

Nitrile Metabolizing Enzymes in Biocatalysis and Biotransformation

Nitrile metabolizing enzymes, i.e., aldoxime dehydratase, hydroxynitrile lyase, nitrilase, nitrile hydratase, and amidase, are the key catalysts in carbon nitrogen triple bond anabolism and catabolism. Over the past several years, these enzymes have drawn considerable attention as prominent biocatalysts in academia and industries because of their wide applications. Research on various aspects of these biocatalysts, i.e., sources, screening, function, purification, molecular cloning, structure, and mechanisms, has been conducted, and bioprocesses at various scales have been designed for the synthesis of myriads of useful compounds. This review is focused on the potential of nitrile metabolizing enzymes in the production of commercially important fine chemicals such as nitriles, carboxylic acids, and amides. A number of opportunities and challenges of nitrile metabolizing enzymes in bioprocess development for the production of bulk and fine chemicals are discussed.     

Angular distributions of light projectile fragments in deep inelastic Pb + Em interactions at 160 A GeV

The nuclear emulsion was exposed at CERN by the lead projectile at 160 A GeV. The angles between any pair of fragments with Z = 2-4 have been measured in the emulsion plane for the events which did not contain heavy fragments. The constant characterizing the normal angle (J) distribution of the fragment momentum projection onto the emulsion plane with respect to initial projectile momentum p₀ is found to be C_J = (0.37 - 0.02) mrad. Corresponding value C₀ = (121 - 6) MeV/c of nucleon momentum distribution in the lead nucleus coincides with that expected from Fermi momentum distribution for this nucleus. The peak in the pair-angle distribution of double-charged fragments, ⁸Be M 2!, is presented for the region of small angles (<0.1 mrad). The fraction of !-particles coming from the decay of the ground state ⁸Be is found to be (13 - 2)% of their whole number.     

Encapsulating Au‐Fe3O4 Nanodots into AIE‐active Supramolecular Assemblies: Ambient Visible‐light Harvesting “Dip‐Strip” Photocatalyst for C−C/C−N Bond Formation Reactions

The present study demonstrates the development of a supramolecular porous ensemble consisting of hetero‐oligophenylene derivative 6 and Au‐Fe₃O₄ nanodots. Supramolecular assemblies of AIE‐active hetero‐oligophenylene derivative 6 served as reactors for the generation of Au‐Fe₃O₄ nanodots. The as prepared supramolecular ensemble functioned as an efficient recyclable photocatalytic system for C(sp²)?H bond activation of anilines for the construction of quinoline carboxylates. Interestingly, the “dip catalyst” prepared by depositing PTh‐co‐PANI‐6: Au‐Fe₃O₄ nanodots on a filter paper served as a recyclable strip (up to 10 cycles) for C?C/C?N bond formation reaction.     

Regulation of metal ion recognition by allosteric effects in thiacalix[4]crown based receptors

Three new ditopic receptors 3a-c based on thiacalix[4]arene of 1,3 alternate conformation possessing two different complexation sites have been designed and synthesized for both soft and hard metal ions. The imino nitrogens bind soft metal ion (Ag⁺/Pb²⁺/Cu²⁺) and the crown moiety binds K⁺ ion. The preliminary investigations show that 3a-c behave as ditopic receptors for Ag⁺/K⁺, Pb²⁺/K⁺, and Cu²⁺/K⁺ ions, respectively. In all the three receptors it was observed that the formation of 3a·Ag⁺/3b·Pb²⁺/3c·Cu²⁺ complex triggers the decomplexation of K⁺ ion from crown moiety and acts as a gateway, which regulates the binding of alkali metal to crown moiety. Thus, allosteric binding between metal ions ‘switch off’ the recognition ability of crown ether ring.     

Stereoselective synthesis and Lewis acid mediated functionalization of novel 3-methylthio-β-lactams

A proficient etiquette for the stereoselective synthesis of novel 3-methylthio-β-lactams and their Lewis acid mediated functionalization is described. Treatment of 2-methylthioethanoic acid and appropriate imines in the Staudinger reaction leads to the stereocontrolled synthesis of novel trans-3-methylthio-β-lactams in excellent yields. cis-3-Chloro-3-methylthio-β-lactams, obtained from stereoselective chlorination of trans-3-methylthio-β-lactams using N-chlorosuccinimide (NCS) and AIBN, were subjected to Lewis acid (TiCl₄ or SnCl₄) mediated functionalization using various active aromatic, heterocyclic and aliphatic compounds (nucleophiles). This reaction provides an easy access to novel, stereoselective cis-3-monosubstituted-3-methylthio-β-lactams, which further undergo smooth desulfurization with Raney-nickel to afford C-3 cis- and trans-monosubstituted-β-lactams. The cis or trans configuration of the hydrogen/chloro/nucleophile substituent at C-3 was assigned with respect to C4–H.     

Voltammetric Sensing of Mercury and Copper Cations at Poly(EDTA‐like) Film Modified Electrode

Complexing polymer‐coated electrodes have been synthesized by oxidative electropolymerization of ethylenediamine tetra‐N‐(3‐pyrrole‐1‐yl)propylacetamide (monomer L ). The presence of four polymerizable pyrrole fragments on the same EDTA skeleton was thought to confer enhanced rigidity and controlled dimensionality to the resulting complexing materials, which were used for the electrochemical detection of Hg(II), Cu(II), Pb(II) and Cd(II) ions by means of the chemical preconcentration‐anodic stripping technique. The polyamide electrode material showed particularly a significant selectivity towards mercury ions, even in the presence of a large excess of other metal cations. Moreover, the use of imprinted polymer‐coated electrodes prepared by electropolymerization of L in the presence of metal cations turned out to significantly improve the detection limits, down to 5×10^?10 mol L^?1 for Hg(II) and Cu(II) species.     

Complexing Polymer Films in The Preparation of Modified Electrodes for Detection of Metal Ions

Summary: The complexing properties of poly (3-(pyrrol-1-yl)propylmalonic acid) (poly1) and poly(N,N′-ethylenebis[N-[(3-(pyrrole-1-yl)propyl) carbamoyl) methyl]-glycine (poly2) coated electrodes (C|poly1 and C|poly2) towards Cu(II), Pb(II), Hg(II) and Cd(II) cations using the open circuit chemical preconcentration-anodic stripping technique were studied. Sorption process of metal cations onto complexing surfaces was readily investigated through the combination of a chemical pre-concentration-anodic stripping technique with a Langmuir isotherm model. The modified electrodes were used for the voltammetric determination of Cu(II), Pb(II), Hg(II) and Cd(II) ions, giving low detection limits for Cu(II) (5 × 10⁻⁹ mol L⁻¹) and Pb(II) (5 × 10⁻¹⁰ mol L⁻¹). The ability of the modified electrodes to analyze Cu(II) ions in natural sample has been demonstrated by the analysis of a tap water sample. The results of the preconcentration process under competitive conditions clearly shows that the selectivity of complexing molecular electrode materials can be subtly tuned upon playing on the accumulation time, polymer thickness and/or memory effect of the binding polymers, opening up new avenues towards evolutive and efficient smart sensing materials.     

一种模拟气液两相流的格子波尔兹曼改进模型

基于格子波尔兹曼自由能模型,提出了一种模拟黏性流场中大密度比气液两相流的改进模型. 为了提高模型的精度,在原始模型的基础上计入了邻近点间粒子数密度的传递速率控制,考虑了碰撞项的差分松弛;为了避免两相间大密度比造成的数值不稳定问题,分别采用六点和九点差分格式求解?和?2. 同时,与传统格子波尔兹曼方法不同,实现了由单步碰撞操作到两步操作的转化. 通过对无重力场中气泡的模拟及与已有模型的计算结果的对比分析,表明该模型具有更高的数值精度. 成功模拟了重力作用下,单个上浮气泡的形变和尾涡形成过程,以及水平和竖直方向上两个气泡的相互作用过程,并验证了其质量守恒和体积不可压缩性.