Synthesis,characterization, electrochemical behaviour and X-ray crystal structures of nickel(II) complexes with a N2O4 donor set macrocyclic Schiff base ligand

Two nickel(II) complexes of [1 + 1] macrocyclic Schiff base ligand (L) have been prepared by cyclocondensation reactions between 1,3-diamino-2-propanol and 2-[3-(2-formylphenoxy)-2-hydroxypropoxy] benzaldehyde, using NiX₂ (X = Br, and I) salts as template agents, and characterized by elemental analyses, IR, molar conductivity and electronic spectra in both solid and solution states. The single-crystal X-ray diffractions of the complexes are also reported that contain nickel(II) ion in a distorted octahedral geometry coordination of N₂O₃X (X = Br, I and NO₃). In all complexes the ligand behaves as a pentadentate ligand. Cyclic voltammetric studies of nickel(II) complexes indicate a quasi-reversible redox wave in the negative potential range.     

Antibacterial and antifungal LDPE films for active packaging

Active antimicrobial packaging is a promising form of active packaging that can kill or inhibit microorganism growth in order to maintain product quality and safety. One of the most common approaches is based on the release of volatile antimicrobial agents from the packaging material such as essential oils. Due to their highly volatile nature, the challenge is to preserve the essential oils during the high‐temperature melt processing of the polymer, while maintaining high antimicrobial activity for a desired shelf life. This study suggests a new approach in order to achieve this goal. Antimicrobial active films are developed based on low‐density polyethylene (LDPE), organo‐modified montmorillonite clays (MMT) and carvacrol (used as an essential oil model). In order to minimize carvacrol loss throughout the polymer compounding, a pre‐compounding step is developed in which clay/carvacrol hybrids are produced. The hybrids exhibit a significant increase in the d‐spacing of clay and enhanced thermal stability. The resulting LDPE/(clay/carvacrol) films exhibit superior and prolonged antibacterial activity against Escherichia coli and Listeria innocua, while polymer compounded with pure carvacrol loses the antibacterial properties within days. The films also present an excellent antifungal activity against Alternaria alternata, used as a model plant pathogenic fungus. Furthermore, infrared spectroscopy analysis of the LDPE/(clay/carvacrol) system displayed significantly higher carvacrol content in the film as well as a slower out‐diffusion of the carvacrol molecules in comparison to LDPE/carvacrol films. Thus, these new films have a high potential for antimicrobial food packaging applications due to their long‐lasting and broad‐spectrum antimicrobial efficacy. Copyright © 2014 John Wiley & Sons, Ltd.     

The X<Superscript>−</Superscript>···benzohydrazide complexes: the interplay between anion-π and H-bond interactions

The compounds containing the benzohydrazide (BH) nucleus have a variety of biological activities because of various noncovalent intermolecular interactions. The interplay between anion-π and H-bond interactions, which can affect the activity of compounds, has been investigated in ten substituted BH exposed to the chloride ion using the quantum mechanical calculations. The total interaction energy is separated into the anion-π (ΔE _Aπ) and H-bond (ΔE _HB) contributions where both interactions are presented in the complexes. The electron-withdrawing substituents (EWSs) increase |ΔE _Aπ| and decrease |ΔE _HB|, while reversed changes are observed with the electron-donating substituents (EDSs). In addition, the total binding energy (ΔE) becomes more/less negative in the presence of EWSs/EDSs. The synergetic effects of mentioned interactions and substituent effects have also been investigated using the atoms in molecules (AIM), natural bond orbital (NBO) and molecular electrostatic potential (MEP) analyses. A good correlation is found between the energy data and the Hammett constants, the minimum of electrostatic potential (V _min) and the results of population analyses.     

Adsorption of Metanil Yellow Azoic Dye from Aqueous Solution onto Mg‐Fe‐NO3 Layered Double Hydroxide

We report the preparation and characterization of a layered double hydroxide (LDH) adsorbent for azoic dye, metanil yellow (yellow GX; YGX) removal. The nanoparticles of Mg‐Fe‐LDH‐NO₃ adsorbent were prepared with Mg/Fe molar ratio of 3:1 by a hydrothermal process and coprecipitation method at pH 9.5 and were characterized by X‐ray powder diffraction (XRPD), thermal gravimetric analysis (TGA), elemental analysis, and Fourier transform infrared spectroscopy (FT‐IR). The size and morphology of nanoparticles were examined by scanning electron microscopy (SEM). The XRD patterns indicate that the intercalation of YGX between the LDH layers has not occurred and surface adsorption has happened. In the adsorption experiments, the Gibbs free energy ΔG⁰ values, the enthalpy ΔH⁰, and entropy ΔS⁰ was determined. The isotherms showed that the adsorption of YGX by Mg‐Fe‐LDH‐NO₃ was both consistent with Langmuir and Freundlich equations.     

Thermal Decomposition Kinetics of Ethane Halides and Derivatives（C_2H_（6-n）X_n（n = 1～3）;X = F,Cl,Br）：DFT Study and NBO Analysis

A theoretical study of the thermal decomposition kinetics of ethane halides(C2H6-nXn(n = 1～3);X = F,Cl,Br) has been carried out at the B3LYP/6-31++G** and B3PW91/631++G** levels of theory.Among these methods and comparison of activation parameters with available experimental values,the B3PW91/6-31++G** method is in good agreement with the experimental data.The analysis of bond order and natural bond orbital(NBO) charges,bond indexes,and synchronicity parameters suggest the elimination of HX in reactions 1～9(HF:compounds 1～3,HCl:compounds 4～6,and HBr:compounds 7～9) occur through a concerted and slightly asynchronous four-membered cyclic transition state type of mechanism.     

Synthesis of Iridium Oxide Nanotubes by Electrodeposition into Polycarbonate Template: Fabrication of Chromium(III) and Arsenic(III) Electrochemical Sensor

For the first time iridium oxide (IrO₂) nanotubes are synthesized by electrodeposition in a polycarbonate (PC) template. Potential cycling (90 cycles) between 0.0 and 0.9 V is used for the preparation of IrO_x nanotubes onto the PC template with a pore diameter of 100 nm. Field‐emission scanning electron microscopy (FESEM) images show, that IrO₂ nanotubes with uniform diameters of 110±10 nm and an estimated length of 1–3 µm are formed. The electrochemical properties and the electrocatalytic activity of a glassy carbon‐IrO_x nanotube modified electrode toward Cr³⁺ and As³⁺ oxidation are investigated. Finally, the modified electrode is used for micromolar detection of the proposed analytes using differential pulse voltammetry.     

Hollow fiber liquid phase microextraction as a preconcentration and clean-up step after pressurized hot water extraction for the determination of non-steroidal anti-inflammatory drugs in sewage sludge

A method for the quantitative determination of non-steroidal anti-inflammatory drugs (NSAIDs) in sewage sludge was developed and validated. The target compounds were extracted using pressurized hot water extraction (PHWE) and then purified and preconcentrated by three-phase hollow fiber liquid phase microextraction (HF-LPME) followed by LC–ESI-MS analysis. The PHWE was optimized with regard to the pH of solvent as well as other operational parameters. The optimum conditions were 0.01 M NaOH as the extraction solvent, temperature of 120 °C, pressure of 100 bar, static time 5 min, 5 cycles, flush volume 90% and purge time 60 s. Spike recoveries for sludge samples spiked at 200 ng g⁻¹ were in the range of 101–109% but for the native drugs in non-spiked sludge samples, recoveries were 38.9%, 59.8%, 90.3% and 47.8% for ketoprofen, naproxen, diclofenac and ibuprofen, respectively. Donor phase pH, ionic strength and extraction time were optimized for HF-LPME after PHWE. The optimum conditions were 2 h extraction at pH 1.5 without salt addition. Enrichment factors in the range of 947–1213 times were achieved (extraction recoveries were 23.6–30.3%) for HF-LPME after PHWE. The matrix effect on the ionization of drugs in LC–ESI-MS was also investigated. The results show that there is a smaller matrix effect (−8.9% to +14.6%) in comparison with other published values obtained using solid phase extraction (SPE) for clean-up after pressurized liquid extraction (PLE). Method detection limits (MDLs) and method quantification limits (MQLs) for different drugs were in the range of 0.4–3.7 ng g⁻¹ and 1.5–12.2 ng g⁻¹ in dried sludge samples, respectively. The characteristics of the proposed method were compared with those of other published works. The considerably lower ion suppression/enhancement and minimum use of organic solvents (a few microliters of di-n-hexyl ether) in the sample preparation step are two highlighted advantages of the proposed method in comparison with previously published works. The method was applied to determine NSAIDs in sewage sludge from Källby wastewater treatment plant (Lund, Sweden) in April, June, August and October 2010. The highest concentration level was recorded for ibuprofen in the April sewage sludge sample (588 ng g⁻¹) and all of the selected NSAIDs were detected in all the samples analyzed.     

微分包含的单调轨道

该文研究微分包含单调轨道的存在性.基于一个新的逼近方法,作者证明了无限维空间中的一个存在性,其特殊情形包含了已有的若于生存定理.     

Extraction of antidepressant drugs in biological samples using alkanol‐based nano structured supramolecular solvent microextraction followed by gas chromatography with mass spectrometric analysis

In the present study, a supramolecular solvent was formed from reverse micelle aggregates of octanol. The proposed supramolecular solvent was used for rapid extraction of some antidepressants drugs including amitriptyline, imipramine, desipramine, maprotiline, sertraline, and doxepin from biological samples. Alkanol‐based supramolecular solvents have a unique array of physicochemical properties, making them a very attractive alternative to replace organic solvents in analytical extractions. The parameters affecting the extraction of target analytes (i.e., the volume of tetrahydrofuran and octanol as the major components comprising the supramolecular solvent, chain length of alkanols, sample solution pH, salt addition, and ultrasonic time) were investigated and optimized by factor by factor optimization method. Under the optimum conditions, preconcentration factors of 470, 490, 460, 385, 370, and 430 were obtained for amitriptyline, doxepin, imipramine, desipramine, maprotiline, and sertraline, respectively. The linear ranges and coefficients of determination (R²) were obtained in the range of 0.01–100 μg/L and 0.9974–0.9991, respectively. Also the limits of detection (S/N = 3) of 0.003–0.03 μg/L, and precisions (n = 5) of 4.9–8.9% were calculated. Finally, the method was successfully applied for the extraction of antidepressant drugs in biological samples, and relative recoveries in the range of 91–102% were obtained.     

A Novel Bacterial Route to Synthesize Cu Nanoparticles and Their Antibacterial Activity

Journal of Cluster Science - This report focuses on a facile and one-pot way to synthesize stable Cu nanoparticles (NPs) through a bacterial approach using an inexpensive and non-toxic copper salt...