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Pin-Wen Huang, Cong-Zhi Wang, Qun-Yan Wu, Jian-Hui Lan, Gang Song, Zhi-Fang Chai, Wei-Qun Shi
Separation of trivalent actinides (An(iii)) and lanthanides (Ln(iii)) in spent nuclear fuel reprocessing is extremely challenging mainly owing to their similar chemical properties. Two amine-type reagents, tetrakis(2-pyridyl-methyl)-1,2-ethylenediamine (TPEN) and its hydrophobic derivative N,N,N',N'-tetrakis((4-butoxypyridin-2-yl)methyl)-ethylenediamine (TBPEN), have been identified to possess a selectivity for Am(iii) over Eu(iii). In this work, the structures, bonding nature, and thermodynamic behaviors of the Am(iii) and Eu(iii) complexes with these two ligands have been systematically studied via scalar relativistic density functional theory (DFT) calculations...
December 13, 2017: Physical Chemistry Chemical Physics: PCCP
Leticia Belén Escudero, Patricia Nora Smichowski, Guilherme Luiz Dotto
In the present work, Iridaea cordata (IC), a red marine macroalgae, was used as an efficient biosorbent for the removal of crystal violet (CV) and methylene blue (MB) dyes from aqueous solutions. The effects of pH (5, 7, and 9) and IC concentration (1, 3, and 5 g L-1) on the biosorption were studied through a 32 full factorial design. Under the optimal conditions (pH: 7, biosorbent concentration: 1 g L-1), biosorption kinetic studies were developed and the obtained experimental data were evaluated by pseudo-first order and pseudo-second order models...
December 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Kartick Lal Bhowmik, Animesh Debnath, Ranendu Kumar Nath, Biswajit Saha
This study reports adsorptive removal of Cr(VI) by magnetic manganese ferrite and manganese oxide nano-particles (MnF-MO-NPs) composite from aqueous media. The X-ray diffraction pattern of MnF-MO-NPs revealed a polycrystalline nature with nanoscale crystallite size. The prepared adsorbent with high Brunauer-Emmett-Teller specific surface area of 100.62 m2/g and saturation magnetization of 30.12 emu/g exhibited maximum Cr(VI) removal at solution pH 2.0 and was easily separated from water under an external magnetic field...
December 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Kazuhiro Fuchizaki, Hironori Nishimura, Takaki Hase, Hiroyuki Saitoh
The similarity in the shape of the melting curve of GeI<sub>4</sub> to that of SnI<sub>4</sub> suggests that a liquid-liquid transition as observed in liquid SnI<sub>4</sub> is also expected to occur in liquid GeI<sub>4</sub>. Because the slope of the melting curve of GeI<sub>4</sub> abruptly changes at around 3 GPa, in situ synchrotron diffraction measurements were conducted to examine closely the structural changes upon compression at around 3 GPa...
December 13, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Juergen Weizenecker
Calculating the dynamic properties of magnetization of single-domain particles is of great importance for the tomographic imaging modality known as magnetic particle imaging (MPI). Although the assumption of instantaneous thermodynamic equilibrium (Langevin function) after application of time-dependent magnetic fields is sufficient for understanding the fundamental behavior, it is essential to consider the finite response times of magnetic particles for optimizing or analyzing various aspects, e.g., interpreting spectra, optimizing MPI sequences, developing new contrasts, and evaluating simplified models...
December 13, 2017: Physics in Medicine and Biology
Valentin Radtke, Andreas Ermantraut, Daniel Himmel, Thorsten Koslowski, Ivo Leito, Ingo Krossing
We describe a procedure for the thermodynamically rigorous, experimental determination of the Gibbs Energy of Transfer of single ions between solvents. The method is based on potential difference measurements between two electrochemical half cells with different solvents connected by an ideal Ionic Liquid Salt Bridge (ILSB). We discuss the specific requirements for the IL with regard to the procedure, ensuring that the Liquid Junction Potentials (LJP) at both ends of the ILSB cancel largely. The remaining parts of the LJPs can be determined by separate emf measurements...
December 13, 2017: Angewandte Chemie
Yongliang Yong, Xiangying Su, Qingxiao Zhou, Yanmin Kuang, Xiaohong Li
Motivated by the recent realization of cluster-assembled nanomaterials as gas sensors, first-principles calculations are carried out to explore the stability and electronic properties of Zn12O12 cluster-assembled nanowires and the adsorption behaviors of environmental gases on the Zn12O12-based nanowires, including CO, NO, NO2, SO2, NH3, CH4, CO2, O2 and H2. Our results indicate that the ultrathin Zn12O12 cluster-assembled nanowires are particularly thermodynamic stable at room temperature. The CO, NO, NO2, SO2, and NH3 molecules are all chemisorbed on the Zn12O12-based nanowires with reasonable adsorption energies, but CH4, CO2, O2 and H2 molecules are only physically adsorbed on the nanowire...
December 13, 2017: Scientific Reports
Pervinder Kaur, Amanpreet Makkar, Paawan Kaur, Shilpa
This study shows the effect of soil type and temperature on the adsorption and desorption behaviour of pendimethalin using a batch equilibration technique. Adsorption kinetics followed pseudo-second-order-model (R2 > 0.99). The shape of adsorption curve for studied soils was S-type at 30 and 40°C and L-type at 50°C. The isotherms were nonlinear and were well described by Freundlich equation. Adsorption capacity ranged from 1.4 to 2.2 μg1 - 1/n g-1 mL1/n and the order of adsorption was: clay loam > sandy loam > loamy sand indicating strong affinity of pendimethalin towards organic matter and clay content...
December 12, 2017: Bulletin of Environmental Contamination and Toxicology
Ghorban Asgari, Alireza Dayari
The data current in this article are associated to the efficacy of acid treated eggshell as eggshell membrane (ESM) as an adsorbent for eliminating cyanide ion from synthetic and industrial wastewaters. This article describes the effects of selected factors such as pH (3-11), contact time (5-60 min), cyanide ion concentrations (50-150 mg/L), ESM dose (0.25-2 g/L), and solution temperature (20-50) on the removal cyanide ion from aqueous solution. The maximum cyanide ion removal obtained at a solution pH of 9-11...
February 2018: Data in Brief
Julie A Spencer, Michael Barclay, Miranda J Gallagher, Robert Winkler, Ilyas Unlu, Yung-Chien Wu, Harald Plank, Lisa McElwee-White, D Howard Fairbrother
The ability of electrons and atomic hydrogen (AH) to remove residual chlorine from PtCl2 deposits created from cis-Pt(CO)2Cl2 by focused electron beam induced deposition (FEBID) is evaluated. Auger electron spectroscopy (AES) and energy-dispersive X-ray spectroscopy (EDS) measurements as well as thermodynamics calculations support the idea that electrons can remove chlorine from PtCl2 structures via an electron-stimulated desorption (ESD) process. It was found that the effectiveness of electrons to purify deposits greater than a few nanometers in height is compromised by the limited escape depth of the chloride ions generated in the purification step...
2017: Beilstein Journal of Nanotechnology
Tathagata Mukherjee, Soumik Biswas, Andreas Ehnbom, Subrata K Ghosh, Ibrahim El-Zoghbi, Nattamai Bhuvanesh, Hassan S Bazzi, John A Gladysz
The title molecules are sought in connection with various synthetic applications. The aliphatic fluorous alcohols Rfn CH2OH (Rfn = CF3(CF2) n-1; n = 11, 13, 15) are converted to the triflates Rfn CH2OTf (Tf2O, pyridine; 22-61%) and then to Rfn CH2I (NaI, acetone; 58-69%). Subsequent reactions with NaOCl/HCl give iodine(III) dichlorides Rfn CH2ICl2 (n = 11, 13; 33-81%), which slowly evolve Cl2. The ethereal fluorous alcohols CF3CF2CF2O(CF(CF3)CF2O) x CF(CF3)CH2OH (x = 2-5) are similarly converted to triflates and then to iodides, but efforts to generate the corresponding dichlorides fail...
2017: Beilstein Journal of Organic Chemistry
Mandar T Naik, Mooseok Kang, Chun-Chen Ho, Pei-Hsin Liao, Yung-Lin Hsieh, Nandita M Naik, Szu-Huan Wang, Iksoo Chang, Hsiu-Ming Shih, Tai-Huang Huang
The negatively charged amino acid-dependent sumoylation motif (NDSM) carries an additional stretch of acidic residues downstream of the consensus Ψ-K-x-E/D sumoylation motif. We have previously shown that acetylation of the SUMO E2 conjugase enzyme, Ubc9, at K65 downregulates its binding to the NDSM and renders a selective decrease in sumoylation of substrates with the NDSM motif. Here, we provide detailed structural, thermodynamic, and kinetics results of the interactions between Ubc9 and its K65 acetylated variant (Ac-Ubc9K65) with three NDSMs derived from Elk1, CBP, and Calpain2 to rationalize the mechanism beneath this reduced binding...
December 12, 2017: Scientific Reports
Yan B Vogel, Long Zhang, Nadim Darwish, Vinicius R Gonçales, Anton Le Brun, J Justin Gooding, Angela Molina, Gordon G Wallace, Michelle L Coote, Joaquin Gonzalez, Simone Ciampi
Predicting or manipulating charge-transfer at semiconductor interfaces, from molecular electronics to energy conversion, relies on knowledge generated from a kinetic analysis of the electrode process, as provided by cyclic voltammetry. Scientists and engineers encountering non-ideal shapes and positions in voltammograms are inclined to reject these as flaws. Here we show that non-idealities of redox probes confined at silicon electrodes, namely full width at half maximum <90.6 mV and anti-thermodynamic inverted peak positions, can be reproduced and are not flawed data...
December 12, 2017: Nature Communications
Vinod Kumar Singh, Vipin Kumar, Annangarachari Krishnamachari
Autonomous replication sequences (ARS) are essential for the replication of Saccharomyces cerevisiae genome. The content and context of ARS sites are distinct from other segments of the genome and these factors influence the conformation and thermodynamic profile of DNA that favor binding of the origin recognition complex proteins. Identification of ARS sites in the genome is a challenging task because of their organizational complexity and degeneracy present across the intergenic regions. We considered a few properties of DNA segments and divided them into multiple subsets (views) for computational prediction of ARS sequences...
December 9, 2017: Bio Systems
Arturo Tozzi, James F Peters, Clifford Chafin, Domenico De Falco, John S Torday
Contrary to claims that physics is timeless while biology is time-dependent, we take the opposite standpoint: physical systems' dynamics are constrained by the arrow of time, while living assemblies are time-independent. Indeed, the concepts of "constraints" and "displacements" shed new light on the role of continuous time flow in life evolution, allowing us to sketch a physical gauge theory for biological systems in long timescales. In the very short timescales of biological systems' individual lives, time looks like "frozen" and "fixed", so that the second law of thermodynamics is momentarily wrecked...
December 9, 2017: Progress in Biophysics and Molecular Biology
Amirhossein Taghavi, Paul van der Schoot, Joshua T Berryman
Using atomistic simulations, we show the formation of stable triplet structure when particular GC-rich DNA duplexes are extended in solution over a timescale of hundreds of nanoseconds, in the presence of organic salt. We present planar-stacked triplet disproportionated DNA (Σ DNA) as a possible solution phase of the double helix under tension, subject to sequence and the presence of stabilising co-factors. Considering the partitioning of the duplexes into triplets of base pairs as the first step of operation of recombinase enzymes like RecA, we emphasise the structure-function relationship in Σ DNA...
January 2017: Quarterly Reviews of Biophysics
Marina A Ortega-Rojas, José Domingo Rivera-Ramírez, C Gabriela Ávila-Ortiz, Eusebio Juaristi, Fernando González-Muñoz, Edmundo Castillo, Jaime Escalante
The use of the solvent engineering has been applied for controlling the resolution of lipase-catalyzed synthesis of β-aminoacids via Michael addition reactions. The strategy consisted of the thermodynamic control of products at equilibrium using the lipase CalB as a catalyst. The enzymatic chemo- and enantioselective synthesis of (R)-(-)-N-benzyl-3-(benzylamino)butanamide is reported, showing the influence of the solvent on the chemoselectivity of the aza-Michael addition and the subsequent kinetic resolution of the Michael adduct; both processes are catalyzed by CalB and both are influenced by the nature of the solvent medium...
December 9, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
A Hosseinian, E Vessally, M Babazadeh, L Edjlali, M Es'haghi
The stable local minima due to the addition of the Li atom to the double-ring and the quasiplanar configurations of the B24 molecule have been searched on the doublet potential energy surface to reveal the structural and electronic features of the Li@B24 system. We report two and seven stable local minima without imaginary vibrational frequency for the Li@B24(double-ring) and the Li@B24(quasiplanar) systems, respectively. The criteria of the adsorption energy, the vertical ionization (VI) energy, the deformation energy, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy gap, the atomic charges, the spin density distribution, the electron transfer (ET), atoms in molecules (AIM) analysis and the nonlinear optical (NLO) properties have been investigated for all the reported molecules of the Li@B24 system in the present paper...
December 7, 2017: Journal of Molecular Graphics & Modelling
J Seelig
Knowledge of protein stability is of utmost importance in various fields of biotechnology. Protein stability can be assessed in solution by increasing the concentration of denaturant and recording the structural changes with spectroscopic or thermodynamic methods. The standard interpretation of the experimental data is to assume a 2-state equilibrium between completely folded and completely unfolded protein molecules. Here we propose a cooperative model based on the statistical-mechanical Zimm-Bragg theory...
December 5, 2017: Biophysical Chemistry
Shun Wan, Pengfei Qiu, Xiangyang Huang, Qingfeng Song, Shengqiang Bai, Xun Shi, Lidong Chen
Recently, the electronegative elements (e.g. S, Se, Cl, and Br) filled skutterudites have attracted great attentions in thermoelectric community. Via doping some electron donors at the Sb sites, these electronegative elements can be filled into the voids of CoSb3 forming thermodynamically stable compounds, which greatly extend the scope of filled skutterudites. In this study, we show that doping appropriate elements at the Co sites can also stabilize the electronegative elements in the voids of CoSb3. A series of SyPdxCo4-xSb12 compounds were successfully fabricated by a traditional solid state reaction method combined with a spark plasma sintering technique...
December 12, 2017: ACS Applied Materials & Interfaces
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