A novel heterogeneous nanocatalyst: 2‐Methoxy‐1‐phenylethanone functionalized MCM‐41 supported Cu(II) complex for C‐S coupling of aryl halides with thiourea

An environmentally friendly copper‐based catalyst supported on 2‐Methoxy‐1‐phenylethanone functionalized MCM‐41 was prepared and characterized by FT‐IR, FE‐SEM, TEM, XRD, EDX, BET and ICP techniques. The catalyst was applied for the C?S cross‐coupling reaction of aryl halides with thiourea. Corresponding products were produced in good yields in aerobic conditions. The catalyst could be recovered and recycled for several times.     

Design and optimization of high-performance microring-based uni-traveling carrier photodiode for WDM optical systems

This paper presents the design principles of a novel optimized microring-based uni-traveling carrier photodiode (MR-UTC-PD), for wavelength division multiplexing (WDM) optical systems. The fundamental parameters for output characteristics such as quantum efficiency and 3-dB bandwidth of MR-UTC-PD are discussed. We analyze the effects of basic parameters as effective ring radius, definite coupling condition and the suitable cross section on the MR-UTC-PD main characteristics for high performance of the device. It is shown that the maximum quantum efficiency and most efficient performance of the device can be obtained at critical coupling condition. We show that the maximum 3-dB bandwidth and an efficient approach for high bandwidth-efficiency product can be achieved at overcoupling condition. In this regard, some design curves are presented for the optimized MR-UTC-PD.     

Enantioselective Diethylzinc Addition to Aromatic Aldehydes Catalyzed by Novel Ti(IV) Complex of Three-Dentate Chiral Sulfonamide Ligands

The synthesis of several novel three-dentate sulfonamide alcohol ligands is described, starting from camphorsulfonyl chloride. The influence of temperature and ligand structure on the asymmetric addition of dietylzinc to aromatic aldehydes has been studied. Enantioselectivities up to 76% have been obtained.     

Adsorption of Cu(II) and Zn(II) ions from aqueous solutions onto fine powder of Typha latifolia L. root: kinetics and isotherm studies

Fine powder of Typha latifolia L. root was used for adsorption of copper and zinc ions from buffered and nonbuffered aqueous solutions. The adsorption reached equilibrium in 60 min. During this time, more than 90 % of the adsorption process was completed. The effect of initial pH, initial concentration of metal ion, and contact time was investigated in a batch system at room temperature. The optimum adsorption performance was observed at pH 5.00 and 4.25 for nonbuffered solutions of Cu(II) and Zn(II), respectively, while for buffered solutions it occurred at pH 6.00. The total metal uptake decreased on application of ammonium acetate buffer, from 37.35 to 17.00 mg g^?1 and 28.80 to 9.90 mg g^?1 for Cu(II) and Zn(II) solutions, respectively, with 100 mg L^?1 initial concentration. The pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models were used to describe the adsorption kinetics. The experimental data followed the pseudo-second-order kinetic model. The biosorption equilibrium was well described by Langmuir and Freundlich isotherm models.     

Preparation of ethylene/α-olefins copolymers using (2-RInd)2ZrCl2/MCM-41 (R:Ph,H) catalyst,microstructural study

(2-RInd)₂ZrCl₂ (R:Ph,H) catalyst was supported on MCM-41 and ethylene copolymerization behavior as well as microstructure of copolymers were studied. A steady rate–time profile behavior was observed for homo and copolymerization of ethylene using supported catalysts. It was noticed that increasing the comonomer content can result in lower physical properties. The obtained results indicated that (2-PhInd)₂ZrCl₂/MCM-41 had higher ability of comonomer incorporation than the non-substituted supported catalysts. The CCC, CCE, and ECC (C: comonomer, E: ethylene) triad sequence distribution in backbone of copolymers were negligible, that means no evidence could be detected for comonomer blocks. The polymer characterization revealed that utilizing 1-octene instead of 1-hexene as the comonomer leads to more heterogeneous distribution of chemical composition. The heterogeneity of the chemical composition distribution and the physical properties were influenced by the type of comonomer and catalyst. (2-PhInd)₂ZrCl₂/MCM-41 produced copolymers containing narrower distribution of lamellae (0.3–1 nm) than the copolymer produce using Ind₂ZrCl₂/MCM-41 (0.3–1.6 nm).     

Per Aqueous Liquid Chromatography (PALC) as a Simple Method for Native Separation of Protein A

Staphylococcal protein A (protein A) is an important protein frequently used in research studies within the fields of biomedicine and biotechnology. Due to some limitations in available protein purification methods which can hold the native structure of the protein A without changing the folding or adding histidine to structure of this protein, its separation in the native form is difficult. In this study, a new cost-effective and powerful technique was introduced for separation of the full-length and truncated forms of recombinant protein A, without any alteration in their 3D structures. Per aqueous liquid chromatography with bare silica gel stationary phase and water:acetonitrile as the mobile phase was proved to be an attractive choice among the range of separation methods. Similar to hydrophilic liquid chromatography, this method employs high percentage of water in mobile phase. The effects of mobile phase composition, pH, and salt concentration on the retention behavior of protein A on bare silica gel stationary phases were investigated. In this method, applying high amounts of aqueous solvent accompanied by a minimum percentage of organic solvent could successfully separate protein A with preservation of folding, and any affinity-tagged group such as histidine has not occurred on its structure. Purity of the fractions obtained by the proposed method was confirmed using SDS-PAGE, western blotting, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. According to the results of ELISA, separated proteins retained their ability of binding to antibody.     

Classification of some large sets and designs

In this paper, we briefly introduce an algorithm, based on the standard basis of trades, which has proven successful in the complete classification of certain combinatorial objects.     

Ultra-trace determination of arsenic species in environmental waters,food and biological samples using a modified aluminum oxide nanoparticle sorbent and AAS detection after multivariate optimization

We describe a simple and efficient method for solid phase extraction and speciation of trace quantities of arsenic. It is based on the use of functionalized aluminum oxide nanoparticles and does not require any oxidation or reduction steps. The experimental parameters affecting extraction and quantitation were optimized using fractional factorial design methods. Adsorbed arsenic was eluted from the sorbent with 1 M hydrochloric acid and determined by graphite furnace atomic absorption spectrometry. Preconcentration factors up to 750 were achieved depending on the sample volume. Studies on potential interferences by various anions and cations showed the method to be highly selective. Under optimum conditions, the calibration plots are linear in the 5.0 to 280 ng L⁻¹ and 8.0 to 260 ng L⁻¹ concentration ranges for As(III) and total arsenic, respectively. The detection limits (calculated for S/N ratios of 3) are 1.81 and 1.97 ng L⁻¹ for As(III) and total arsenic, respectively. The method was successfully applied to the determination and speciation of arsenic in (spiked) environmental, food and biological samples and gave good recoveries. The method was validated using a certified geological reference material.

Novel functionalized Al₂O₃ nanoparticles were synthesized and used for speciation and determination of arsenic in different samples. The experimental variables were optimized using fractional factorial design that can save time and operational costs.

     

Solid-phase extraction of Pb2+ ion from environmental samples onto L-AC-Ag-NP by flame atomic absorption spectrometry (FAAS)

The development of a solid-phase extraction (SPE) procedure for the pre-concentration of trace amounts of Pb²⁺ ion on 2-furan-2-yl-1-furan-2-ylmethyl-1H-benzoimidazole loaded on activated carbon modified with silver nanoparticles (L-AC-Ag-NP) was presented. The metal ion retained on the sorbent was quantitatively determined via complexation with the ligand. The complexed metal ion was efficiently eluted using 10 mL of 4 mol L^?1 sulphuric acid in 10 w/v% acetone. The influences of the analytical parameters, including pH, amounts of the ligand and the solid phase, eluent conditions and sample volume, on the recoveries of the metal ion were optimised. Using the optimised parameters, the linear response of the SPE method for Pb²⁺ ion were in the ranges of 0.2–160 µg L^?1, and the detection limit for Pb²⁺ ion was 0.034 µg L^?1. The proposed method exhibits a pre-concentration factor (PF) of 80 and an enhancement factor of 30 for Pb²⁺ ion. The presented results demonstrate the successful application of the proposed method for the determination of Pb²⁺ ion in some real samples with high recoveries (>93%) and reasonable relative standard deviation (RSD < 2%).