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...     

Enhanced Heterotrophic Denitrification: Effect of Dairy Industry Sludge Acclimatization and Operating Conditions

Heterotrophic denitrification of drinking water was enhanced by selection of an anoxic sludge taken from a dairy industry among the sludges taken from various industries, and the effect of carbon sources was examined. Acclimatization to high nitrate concentration was then carried out in a five-stage process. Considering removals of both nitrate and nitrite, the sludge taken from anoxic unit of Tehran Pegah dairy industry was shown to be the superior microbial culture, with ethanol as carbon source as compared to acetate. To enhance the rate of denitrification, acclimatization to nitrate (at 100, 200, 400, 800, and 1,600 mg N-NO₃/L) was carried out in sequencing batch reactors over a 3-month period under anoxic condition, and comparisons were made between the performances of acclimated and non-acclimated sludges at each stage. It was found that acclimatization up to the fourth stage enhanced the specific denitrification rate to a high value of 29.6 mg N-NO₃/h/g mixed liquor suspended solids (MLSS), with no significant nitrite accumulation. Additionally, the effect of initial pH (6, 6.5, 7, and 7.5) and carbon-to-nitrogen (C/N) ratio (1, 1.5, 2, and 3) on the performance of this final acclimated sludge was assessed, where initial pH of 7 and C/N ratio of 1.5 resulted in the best performances considering both nitrate and nitrite removal.     

Isometries between completely regular vector-valued function spaces

Periodica Mathematica Hungarica - In this paper, first we study surjective isometries (not necessarily linear) between completely regular subspaces A and B of $$C_0(X,E)$$ and $$C_0(Y,F)$$ where X...     

Terpolymerization of Triisopropylsilyl Acrylate,Methyl Methacrylate,and Butyl Acrylate: Reactivity Ratio Estimation

Ternary monomer reactivity ratios of triisopropylsilyl acrylate (SiA), methyl methacrylate (MMA), and n‐butyl acrylate (BA), as common monomers in self‐polishing coatings (SPCs) binders are obtained using experimental data collected from free radical bulk polymerization at 70 °C. Different terpolymerizations at low and medium‐high conversions are performed at optimized feed compositions. Estimations are made using the error‐in‐variables model (EVM) framework, applying the recast form of the Alfrey–Goldfinger (AG) model and a direct numerical integration (DNI) approach to the collected data. Estimations from individual low and medium‐high conversion data are compared to those found with the combined data (full conversion range data). The highest certainty in point estimates are obtained with analysis of the full conversion range data. Furthermore, the reactivity ratios determined from the combined data fall between those found with analysis of individual low and medium‐high conversion data, another corroboration of reliable data collection. Reactivity ratios determined from analysis of the combined data (r_SiA/MMA = 0.4185, r_MMA/SiA = 1.3754, r_SiA/BA = 0.8739, r_BA/SiA = 0.5736, r_BA/MMA = 0.3692, r_MMA/BA = 1.7919) are used in the recast AG model to predict cumulative terpolymer composition as a function of conversion. The experimental data and model prediction show satisfactory agreement.     

Preparation and characterization of polyurethane based self-cleaning and antibacterial coating containing silver ion exchanged montmorillonite/TiO<Subscript>2</Subscript> nanocomposite

In order to reach an antibacterial, photocatalytic, and hydrophilic coating, commercial grade polyurethane (CPU) resin was modified with silver ion exchanged montmorillonite/TiO₂ nanocomposite in various montmorillonite to TiO₂ nanoparticle ratios. To characterize the prepared nanocomposites and coatings, X-ray diffraction patterns, FTIR and UV–Vis spectroscopy and SEM images were used. The modified commercial grade polyurethane coatings containing nanocomposites show better properties, including hydrophilicity, degradation of organic pollutants, antibacterial activity and water resistivity, compared to unmodified commercial grade polyurethane coatings. The water droplet contact angle of unmodified CPU coating was 70°, however it decreased to lower than 10° in modified CPU coatings after 24 h LED lamp irradiation. Decolorization efficiency of malachite green dye solution by the use of modified CPU coatings achieved up to 70% after 5 h LED lamp illumination, compared to less than 5% for unmodified CPU coatings. Modified CPU coatings also showed significant water resistivity and antibacterial properties.     

Investigation of chiral recognition by molecular micelles with molecular dynamics simulations

Molecular dynamics simulations were used to characterize the binding of the chiral drugs chlorthalidone and lorazepam to the molecular micelle poly-(sodium undecyl-(L)-leucine-valine). The project’s goal was to characterize the nature of chiral recognition in capillary electrophoresis separations that use molecular micelles as the chiral selector. The shapes and charge distributions of the chiral molecules investigated, their orientations within the molecular micelle chiral binding pockets, and the formation of stereoselective intermolecular hydrogen bonds with the molecular micelle were all found to play key roles in determining where and how lorazepam and chlorthalidone enantiomers interacted with the molecular micelle.     

Phytochemical fabrication,characterization, and antioxidant application of copper and cobalt oxides nanoparticles using <Emphasis Type="Italic">Sesbania sesban</Emphasis> plant

In this work, an ecofriendly and economic strategy for synthesize of CuO and Co₃O₄ were developed using extracted Sesbania sesban solution (ESS) as a reducing and stabilizing agent, and bioreactor. These novel nano metal oxides (NMOs) were characterized by high-resolution-transmission electron microscopy (TEM), EDAX thermo gravimetric analysis and X-ray diffraction (XRD). Morphology and size of them were investigated by TEM and the average sizes of for spherical CuO and Co₃O₄ nanoparticles are 20–40 and 15–30 nm, respectively. The XRD and EDAX confirmed the high purity for NMOs. The thermal behaviors of the NMOs exhibited good crystallographic stability within the investigated temperature range. The antioxidant and antibacterial activities of NMOs were investigated and compared to manganese(III) meso-tetraphenylporphyrin complex/Ag nanocomposite (Ag/P nanocomposite) synthesizing by ESS. The results obtained from this work showed that copper(II) oxide, cobalt oxide nanoparticles, and Ag/P nanocomposite have DPPH scavenging activity. On the other hand, NMOs have no antibacterial activity against Gram-negative bacterial strains. Cobalt oxide nanoparticles have antibacterial activity against Staphylococcus aureus, while Ag/P nanocomposite showed the antibacterial activities against both Gram-negative and Gram-positive bacterial strains.     

Theoretical kinetic study of two competing paths in the H2O2 + O(P) → HO2 + OH reaction

Ab initio-TST calculations were carried out to study the kinetics of the title reaction. The H atom and the OH abstraction paths leading to the same products HO₂ and OH have been considered. The ZPE and BSSE corrected classical barrier heights were predicted to be 7.4 and 17.3 kcal/mol, respectively. Calculated thermal rate constants over the temperature range 300–5000 K showed that the H-abstraction path was the most likely to occur for temperatures below 2500 K which confirms the result found in a previous study [Y. Tarchouna, M. Bahri, N. Jaïdane, Z. Ben Lakdar, J. Mol. Struct. (Theochem), 189 (2003) 664]. The contribution of OH abstraction path to the reaction was predicted to be important for high temperatures.     

Chelate structures of 5-(H/Br)-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazones (H2L): Synthesis and structural characterizations of [Ni(L)(PPh3)] and [Ru(HL)2(PPh3)2]

The reactions of 5-R-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazone {R: H (L¹); Br (L²)} with [M^II(PPh₃)nCl₂] (M = Ni, n = 2 and M = Ru, n = 3) in a 1:1 molar ratio have given stable solid complexes corresponding to the general formula [Ni(L)(PPh₃)] and [Ru(HL)₂(PPh₃)₂]. While the 1:1 nickel complexes are formed from an ONS donor set of the thiosemicarbazone and the P atom of triphenylphosphine in a square planar structure, the 1:2 ruthenium complexes consist of a couple from each of N, S and P donor atoms in a distorted octahedral geometry. These mixed-ligand complexes have been characterized by elemental analysis, IR, UV–Vis, APCI-MS, ¹H and ³¹P NMR spectroscopies. The structures of [Ni(L²)(PPh₃)] (II) and [Ru(L¹H)₂(PPh₃)₂] (III) were determined by single crystal X-ray diffraction.