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https://www.readbyqxmd.com/read/28922641/structural-luminescence-thermodynamic-and-theoretical-studies-on-mononuclear-complexes-of-eu-iii-with-pyridine-monocarboxylate-n-oxides-in-aqueous-solution
#1
Rama Mohana Rao Dumpala, Neetika Rawat, Anil Boda, Sk Musharaf Ali, B S Tomar
The mononuclear complexes formed by Eu(III) with three isomeric pyridine monocarboxylate-N-oxides namely picolinic acid-N-oxide (PANO), nicotinic acid-N-oxide (NANO) and isonicotinic acid-N-oxide (IANO) in aqueous solutions were studied by potentiometry, luminescence spectroscopy and isothermal titration calorimetry (ITC) to determine the speciation, coordination, luminescence properties and thermodynamic parameters of the complexes formed during the course of the reaction. More stable six membered chelate complexes with stoichiometry (MLi, i=1-4) are formed by Eu(III) with PANO while non chelating ML and ML2 complexes are formed by NANO and IANO...
September 9, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28911271/chitosan-modification-persimmon-tannin-bioadsorbent-for-highly-efficiency-removal-of-pb-ii-from-aqueous-environment-the-adsorption-equilibrium-kinetics-and-thermodynamics
#2
Xiaojuan Li, Zhongmin Wang, Haijun Liang, Jingliang Ning, Guiyin Li, Zhide Zhou
Lead (Pb) pollution has triggered a great threat to ecological system as well as public health due to its highly toxic and mutagenic properties. In this study, chitosan surface modified persimmon tannin (PT-CS) biomass composite as an environmental friendly bioadsorbent for highly efficient removal of Pb(II) from aqueous solutions was investigated. FT-IR, XRD, SEM, BET, XPS and Zeta potential were used to elucidate the adsorption mechanism. Combining of oxidation reaction, electrostatic interaction and chelation reaction, PT-CS exhibited fine adsorption performance to Pb(II)...
September 15, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28898583/electronic-structures-of-small-ruo2-n-n-1-to-4-nanoclusters-and-their-anions-and-the-hydrolysis-reactions-with-water
#3
Zongtang Fang, Michael A Outlaw, David A Dixon
Group 8 (RuO2)n (n= 1 to 4) nanoclusters, their anions and the hydrolysis reactions of the neutral clusters have been studied with the density functional theory (DFT) as well as coupled cluster CCSD(T) theory. The ground state is predicted to be a singlet and a doublet for the neutral RuO2 clusters and anionic clusters, respectively. The CCSD(T) method is required to predict the correct ground state. The calculated singlet-triplet gaps ( < 15 kcal/mol) and fluoride affinities ( < 95 kcal/mol) are smaller than those of the Group 4 (MO2)n and Group 6 (MO3)n metal oxide clusters...
September 12, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28876255/naa-zeolite-derived-from-blast-furnace-slag-its-application-for-ammonium-removal
#4
Hongwei Guo, Lizhen Tang, Bingji Yan, Kang Wan, Peng Li
In this paper, high value added NaA zeolite material was prepared from blast furnace (BF) slag by hydrothermal method and its adsorption behavior on the removal of ammonium ion was investigated. It was found out that the synthetic NaA cubic zeolite with smaller crystal size obtained at nSiO2/nAl2O3 = 2 and nH2O/nNaOH = 20 showed better adsorption performance. The kinetics of the adsorption of ammonium ion by synthesized NaA zeolite was fitted by the pseudo-second-order kinetic model. The intra-particle diffusion modeling reveals that two mixed rate-controlling mechanisms were involved in the adsorption process...
September 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28827426/phase-transformation-induced-lubrication-of-earthquake-sliding
#5
Harry W Green
Frictional failure is not possible at depth in Earth, hence earthquakes deeper than 30-50 km cannot initiate by overcoming dry friction. Moreover, the frequency distribution of earthquakes with depth is bimodal, suggesting another change of mechanism at about 350 km. Here I suggest that the change at 30-50 km is from overcoming dry friction to reduction of effective stress by dehydration embrittlement and that the change at 350 km is due to desiccation of slabs and initiation by phase-transformation-induced faulting...
September 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28808598/synthesis-characterization-and-adsorptive-properties-of-fe3o4-go-nanocomposites-for-antimony-removal
#6
Xiuzhen Yang, Tengzhi Zhou, Bozhi Ren, Zhou Shi, Andrew Hursthouse
A magnetic Fe3O4/GO composite with potential for rapid solid-liquid separation through a magnetic field was synthesized using GO (graphene oxide) and Fe3O4 (ferriferous oxide). Characterization of Fe3O4/GO used scanning electron microscope (SEM), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR), and Vibrating Sample Magnetometer (VSM). A number of factors such as pH and coexisting ions on adsorbent dose were tested in a series of batch experiments. The results showed that GO and Fe3O4 are strongly integrated...
2017: Journal of Analytical Methods in Chemistry
https://www.readbyqxmd.com/read/28805386/solvation-effect-on-complexation-of-alkali-metal-cations-by-a-calix-4-arene-ketone-derivative
#7
Josip Požar, Ivana Nikšić-Franjić, Marija Cvetnić, Katarina Leko, Nikola Cindro, Katarina Pičuljan, Ivana Borilović, Leo Frkanec, Vladislav Tomišić
The medium effect on the complexation of alkali metal cations with a calix[4]arene ketone derivative (L) was systematically examined in methanol, ethanol, N-methylformamide, N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile. In all solvents the binding of Na(+) cation by L was rather efficient, whereas the complexation of other alkali metal cations was observed only in methanol and acetonitrile. Complexation reactions were enthalpically controlled, while ligand dissolution was endothermic in all cases...
August 31, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28799041/synergistic-interface-behavior-of-strontium-adsorption-using-mixed-microorganisms
#8
Wenyuan Hu, Faqin Dong, Guangmin Yang, Xin Peng, Xiaojun Huang, Mingxue Liu, Jing Zhang
The proper handling of low-level radioactive waste is crucial to promote the sustainable development of nuclear power. Research into the mechanism for interactions between bacterium and radionuclides is the starting point for achieving successful remediation of radionuclides with microorganisms. Using Sr(II) as a simulation radionuclide and the mixed microorganisms of Saccharomyces cerevisiae and Bacillus subtilis as the biological adsorbent, this study investigates behavior at the interface between Sr(II) and the microorganisms as well as the mechanisms governing that behavior...
August 10, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28769001/selected-physicochemical-and-biological-properties-of-ethyl-ascorbic-acid-compared-to-ascorbic-acid
#9
Iwona Golonka, Monika Oleksy, Adam Junka, Agnieszka Matera-Witkiewicz, Marzenna Bartoszewicz, Witold Musiał
The aim of the work was the evaluation of selected biological and physicochemical, applicative properties of ethylated ascorbic acid (AAE) compared to ascorbic acid (AA). Thermogravimetry (TG), differential thermogravimetry (DTG), and differential thermal analysis (DTA) were conducted, followed by the evaluation of AAE decomposition by the UV-Vis spectroscopic method including the influence of temperature and pH. Scavenging, antimicrobial activity and cytotoxicity against L929 fibroblasts were also performed...
2017: Biological & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/28726415/enhanced-diffusion-of-passive-tracers-in-active-enzyme-solutions
#10
Xi Zhao, Krishna K Dey, Selva Jeganathan, Peter J Butler, Ubaldo M Córdova-Figueroa, Ayusman Sen
Colloidal suspensions containing microscopic swimmers have been the focus of recent studies aimed at understanding the principles of energy transfer in fluidic media at low Reynolds number conditions. Going down in scale, active enzymes have been shown to be force-generating, nonequilibrium systems, thus offering opportunity to examine energy transfer at the ultralow Reynolds number regime. By monitoring the change of diffusion of inert tracers dispersed in active enzyme solutions, we demonstrate that the nature of energy transfer in these systems is similar to that reported for larger microscopic active systems, despite the large differences in scale, modes of energy transduction, and propulsion...
July 26, 2017: Nano Letters
https://www.readbyqxmd.com/read/28720966/biochemical-characterization-and-thermal-inactivation-of-polyphenol-oxidase-from-elephant-foot-yam-amorphophallus-paeoniifolius
#11
Anuradha Singh, Neeraj Wadhwa
Polyphenol oxidase from Amorphophallus corm was purified (5.54 fold) by acetone precipitation and ion exchange chromatography. Electrophoretic-blot analysis revealed that the molecular weight of enzyme is 40 kDa. Enzyme preferred catechol as substrate and showed optimum activity at pH 6 and 35 °C with Km of 17.56 mM and Vmax 0.023 U/ml/min. Thermal inactivation kinetics study showed that 5.68% inactivation was achieved at 75 °C within 40 min. The half-life time of PPO is between 126.00 and 32.54 min...
June 2017: Journal of Food Science and Technology
https://www.readbyqxmd.com/read/28715681/adsorption-of-nh4-n-on-chinese-loess-non-equilibrium-and-equilibrium-investigations
#12
Haijian Xie, Shaoyi Wang, Zhanhong Qiu, Jianqun Jiang
NH4(+)-N is a crucial pollutant in landfill leachate and can be in high concentrations for a long period of time due to anaerobic condition of landfills. The adsorption properties of NH4(+)-N on the Chinese loess were investigated using Batch test. The influences of ammonium concentration, temperature, reaction time, slurry concentration, and pH on the adsorption process are evaluated. Adsorption kinetics and isotherm behaviors were studied by applying different models to the test data to determine the adsorption parameters...
July 14, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28710960/bioremediation-potential-of-arsenic-by-non-enzymatically-biofabricated-silver-nanoparticles-adhered-to-the-mesoporous-carbonized-fungal-cell-surface-of-aspergillus-foetidus-mtcc8876
#13
Triparna Mukherjee, Shatarupa Chakraborty, Aksar Ali Biswas, Tapan Kumar Das
Our study aiming for the diminution of arsenic concentration in arsenic contaminated aqua environment by using novel adsorbents based on bio-fabricated silver nanoparticles on a fungal cell surface. Bioreduction of silver ion was done in a non-enzymatic manner in presence of the biomass of fungus Aspergillus foetidus MTCC8876. Aspergillus spp. cells were harvested following the bioreduction and made into carbon by carbonization that led to pore formation (pore width of 2.35 nm) on the cell surface. The average size of silver nanoparticles in the sample of SACF (silver nanoparticles adhered to mesoporous carbonized fungal cell) was 35 nm...
July 12, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28708608/magnetic-schiff-s-base-sorbent-based-on-shrimp-peels-wastes-for-consummate-sorption-of-chromate
#14
Khalid Z Elwakeel, Ahmed M Elgarahy, Samya H Mohammad
Magnetic Schiff's base chitosan composite has been prepared starting from shrimp peels as a raw material. Chitosan extraction involved three main stages as preconditioning, demineralization deproteinization and deacetylation. Chitosan modification process took place through the reaction between chitosan and polymeric Schiff's base of thiourea/glutaraldehyde in the presence of magnetite. The synthetic hybrid composite was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy-energy dispersive X-ray analyses and tested as sorbent for Cr(VI) recovery from aqueous solution...
July 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28692096/a-quantum-rovibrational-state-selected-study-of-the-proton-transfer-reaction-h2-x-2-%C3%AE-v-1-3-n-0-3-ne-%C3%A2-neh-h-using-the-pulsed-field-ionization-photoion-method-observation-of-the-rotational-effect-near-the-reaction-threshold
#15
Bo Xiong, Yih-Chung Chang, Cheuk-Yiu Ng
Using the sequential electric field pulsing scheme for vacuum ultraviolet (VUV) laser pulsed field ionization-photoion (PFI-PI) detection, we have successfully prepared H2(+)(X(2)Σ: v(+) = 1-3; N(+) = 0-5) ions in the form of an ion beam in single quantum-rovibrational-states with high purity, high intensity, and narrow laboratory kinetic energy spread (ΔElab ≈ 0.05 eV). This VUV-PFI-PI ion source, when coupled with the double-quadrupole double-octupole ion-molecule reaction apparatus, has made possible a systematic examination of the vibrational- as well as rotational-state effects on the proton transfer reaction of H2(+)(X(2)Σ: v(+); N(+)) + Ne...
July 10, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28691770/influence-of-the-water-phase-state-on-the-thermodynamics-of-aqueous-phase-reforming-for-hydrogen-production
#16
Séverine Le Gac, Renée M Ripken, Jan Meuldijk, Johannes G E Gardeniers
Hydrogen is a promising renewable energy source that can be produced from biomass using Aqueous Phase Reforming (APR). Here, using data obtained from AspenPlus and the literature, we evaluated the phase state, temperature-dependent enthalpy, and Gibbs free energy for the APR of small biomass model substrates. Phase equilibrium studies reveal that, under typical APR reaction conditions, the reaction mixture is in the liquid phase. Therefore, we show for the first time that the water-gas-shift (WGS), which is the second main reaction of APR, must be modeled in the liquid phase, resulting in an endothermic instead of an exothermic enthalpy of reaction...
July 10, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28686937/effective-removal-of-phosphate-from-aqueous-solution-using-humic-acid-coated-magnetite-nanoparticles
#17
Mamun Rashid, Nathaniel T Price, Miguel Ángel Gracia Pinilla, Kevin E O'Shea
Effective removal of excess phosphate from water is critical to counteract eutrophication and restore water quality. In this study, low cost, environmentally friendly humic acid coated magnetite nanoparticles (HA-MNP) were synthesized and applied for the remediation of phosphate from aqueous media. The HA-MNPs, characterized by FTIR, TEM and HAADF-STEM showed the extensive coating of humic acid on the magnetite surface. The magnetic nanoparticles with diameters of 7-12 nm could be easily separated from the reaction mixture by using a simple hand held magnet...
June 30, 2017: Water Research
https://www.readbyqxmd.com/read/28684353/removal-of-cd-ii-and-cr-vi-ions-by-highly-cross-linked-thiocarbohydrazide-chitosan-gel
#18
Ronghua Li, Wen Liang, Manlin Li, Shuncheng Jiang, Hui Huang, Zengqiang Zhang, Jim J Wang, Mukesh Kumar Awasthi
A highly cross-linked Thiocarbohydrazide-modified chitosan (TCCS) gel was synthesized by using formaldehyde as linkage, and was used in removal of Cd(II) and Cr(VI) from aqueous solution. The results showed that TCCS could be used in a wider pH range and had higher adsorption abilities than raw chitosan for Cd(II) and Cr(VI) ions. The maximum adsorption capacities of the synthetic TCCS for two ions reached 81.26 and 144.68mg/g at 298K, respectively. The endothermic adsorption exhibited pseudo-second-order kinetic behavior and the adsorption isotherm could be well described by Langmuir model...
November 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28672109/effect-of-barley-%C3%AE-glucan-on-the-gluten-polymerization-process-in-dough-during-heat-treatment
#19
Ze-Hua Huang, Yang Zhao, Ke-Xue Zhu, Xiao-Na Guo, Wei Peng, Hui-Ming Zhou
Barley (Hordeum vulgare L.) β-glucan (BBG) is of interest as a result of its health benefits, but BBG presents significant disruptions on the gluten network, with a negative impact on food texture. To clarify the interaction between BBG and gluten in dough, the dynamic rheological, thermochemical process of gluten and microstructure of dough with BBG during heating were detected. The results showed that BBG delayed the gluten thermopolymerization reaction during heating and affected polymerization of specific molecular weight protein subunits...
July 26, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28638992/a-qm-mm-study-on-the-enzymatic-inactivation-of-cefotaxime
#20
Ignacio Lizana, Eduardo J Delgado
The reaction between the antibiotic cefotaxime and the CTX-M-14 class A serine hydrolase is addressed from a theoretical point of view, by means of hybrid quantum mechanics/molecular mechanical (QM/MM) calculations, adopting a new approach that postulates that the residue Ser70 itself should play the role of the acid-base species required for the cefotaxime acylation. The proposed mechanism differs from earlier proposals existing in literature for other class A β-lactamases. The results confirm the hypothesis, and show that the reaction should occur via a concerted mechanism in which the acylation of the lactam carbonyl carbon, protonation of the N7 lactam atom, and opening of the β-lactam ring occurs simultaneously...
July 2017: Journal of Molecular Modeling
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