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https://www.readbyqxmd.com/read/28088121/synthesis-of-ctab-intercalated-graphene-and-its-application-for-the-adsorption-of-ar265-and-ao7-dyes-from-water
#1
Mohammed Yusuf, Moonis Ali Khan, Marta Otero, E C Abdullah, Masaaki Hosomi, Akihiko Terada, Shohei Riya
Environmental applications of graphene (GN) are limited by the occurrence of aggregation. Herein, graphene oxide (GO) was synthesized, reduced to GN by ascorbic acid, and intercalated with cetyltrimethylammonium bromide (CTAB). GN-CTAB was characterized by Boehm's titration, N2 adsorption/desorption, Fourier transform infrared spectroscopy, Raman spectroscopy, Fluorescence spectrophotometry, X-ray diffraction and Scanning electron microscopy. Then, GN-CTAB was used for the adsorptive removal of acid red 265 (AR265) and acid orange 7 (AO7) dyes from water both under batch and column operation...
January 5, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28081593/percutaneous-cryoablation-for-hepatocellular-carcinoma
#2
Kyoung Doo Song
Local ablation therapy is considered as a conventional treatment option for patients with early stage hepatocellular carcinoma (HCC). Although radiofrequency (RF) ablation is widely used for HCC, the use of cryoablation has been increasing as newer and safer cryoablation systems have developed. The thermodynamic mechanism of freezing and thawing used in cryoablation is the Joule-Thomson effect. Cryoablation destroys tissue via direct tissue destruction and vascular-related injury. A few recent comparative studies have shown that percutaneous cryoablation for HCCs is comparable to percutaneous RF ablation in terms of long term therapeutic outcomes and complications...
December 2016: Clinical and Molecular Hepatology
https://www.readbyqxmd.com/read/28080051/prediction-of-bond-dissociation-energies-heat-of-formation-for-diatomic-transition-metal-compounds-ccsd-t-works
#3
Zongtang Fang, Monica Vasiliu, Kirk A Peterson, David A Dixon
It was recently reported (J. Chem. Theory Comput. 2015, 11, 2036-2052) that the coupled cluster singles and doubles with perturbative triples method, CCSD(T), should not be used as a benchmark tool for the prediction of dissociation energies (heats of formation) for the 1st row transition metal diatomics based on a comparison with the experimental thermodynamic values for a set of 20 diatomics. In the present work the bond dissociation energies as well as the heats of formation for those diatomics have been calculated by the Feller-Peterson-Dixon approach at the CCSD(T)/complete basis set (CBS) level of theory including scalar relativistic corrections and correlation of the outer shell of core electrons in addition to the valence electrons...
January 12, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28080028/a-grand-avenue-to-au-nanocluster-electrochemiluminescence
#4
Mahdi Hesari, Zhifeng Ding
In most cases of semiconductor quantum dot nanocrystals, the inherent optical and electrochemical properties of these interesting nanomaterials do not translate into expected efficient electrochemiluminescence or electrogenerated chemiluminescence (ECL) because of the surface-state induction effect. Thus, their low ECL efficiencies, while very interesting to explore, limit their applications. As their electrochemistry is not well-defined, insight into their ECL mechanistic details is also limited. Alternatively, gold nanoclusters possess monodispersed sizes with atomic precision, low and well defined HOMO-LUMO energy gaps, and stable optical and electrochemical properties that make them suitable for potential ECL applications...
January 12, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28079906/4d-and-5d-bimetal-doped-tubular-silicon-clusters-si12m2-with-m-nb-ta-mo-and-w-a-bimetallic-configuration-model
#5
Hung Tan Pham, Devashis Majumdar, Jerzy Leszczynski, Minh Tho Nguyen
Geometries and electronic properties related to the ground state stabilities of several Si12M2 clusters (M: second-row (Nb and Mo) and third-row (Ta and W) transition metals, and their mixed bimetallic clusters M2: NbMo and TaW) were explored using density functional theory (DFT) computations. The computed results show that two different structural motifs emerge as the global energy minima of such clusters. They are basically singlet tubular structures in either a C2v prism ((1)A1) or a C6v antiprism ((1)A1) form...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28079371/a-binding-pose-flip-explained-via-enthalpic-and-entropic-contributions
#6
Michael Schauperl, Paul Czodrowski, Julian E Fuchs, Roland G Huber, Birgit J Waldner, Maren Podewitz, Christian Kramer, Klaus R Liedl
The anomalous binding modes of five highly similar fragments of TIE2 inhibitors, showing three distinct binding poses are investigated. We report a quantitative rationalization for the changes in binding pose based on molecular dynamics simulations. We investigated five fragments in complex with the transforming growth factor β receptor type 1 kinase domain. Analyses of these simulations using Grid Inhomogeneous Solvation Theory (GIST), pKA calculations, and a tool to investigate enthalpic differences upon binding unraveled the various thermodynamic contributions to the different binding modes...
January 12, 2017: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/28079211/electrolyte-controlled-discharge-product-distribution-of-na-o2-batteries-a-combined-computational-and-experimental-study
#7
Beizhou Wang, Ning Zhao, Youwei Wang, Wenqing Zhang, Wencong Lu, Xiangxin Guo, Jianjun Liu
Tuning the composition of discharge products is an important strategy to reduce charge potential, suppress side reactions, and improve the reversibility of metal-oxygen batteries. In the present study, first-principles calculations and experimental confirmation were performed to unravel the influence of O2 pressure, particle size, and electrolyte on the composition of charge products in Na-O2 batteries. The electrolytes with medium and high donor numbers (>12.5) are favorable for the formation of sole NaO2, while those with low donor numbers (<12...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28078904/malonyl-coa-pathway-a-promising-route-for-3-hydroxypropionate-biosynthesis
#8
Changshui Liu, Yamei Ding, Mo Xian, Min Liu, Huizhou Liu, Qingjun Ma, Guang Zhao
3-Hydroxypropionate (3HP) is an attractive platform chemical, serving as a precursor to a variety of commodity chemicals like acrylate and acrylamide, as well as a monomer of a biodegradable plastic. To establish a sustainable way to produce these commercially important chemicals and materials, fermentative production of 3HP is widely investigated in recent years. It is reported that 3HP can be produced from several intermediates, such as glycerol, malonyl-CoA, and β-alanine. Among all these biosynthetic routes, the malonyl-CoA pathway has some distinct advantages, including a broad feedstock spectrum, thermodynamic feasibility, and redox neutrality...
January 12, 2017: Critical Reviews in Biotechnology
https://www.readbyqxmd.com/read/28077763/a-simplified-mathematical-model-of-directional-dna-site-specific-recombination-by-serine-integrases
#9
Alexandra Pokhilko, Jia Zhao, W Marshall Stark, Sean D Colloms, Oliver Ebenhöh
Serine integrases catalyse site-specific recombination to integrate and excise bacteriophage genomes into and out of their host's genome. These enzymes exhibit remarkable directionality; in the presence of the integrase alone, recombination between attP and attB DNA sites is efficient and irreversible, giving attL and attR products which do not recombine further. However, in the presence of the bacteriophage-encoded recombination directionality factor (RDF), integrase efficiently promotes recombination between attL and attR to re-form attP and attB The DNA substrates and products of both reactions are approximately isoenergetic, and no cofactors (such as adenosine triphosphate) are required for recombination...
January 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28076957/collapse-precedes-folding-in-denaturant-dependent-assembly-of-ubiquitin
#10
Govardhan Reddy, Dave Thirumalai
The folding of small protein Ubiquitin (Ub), which plays an indispensable role in targeting proteins for degradation and DNA damage response is complex. A number of experiments on Ub folding have reached differing conclusions regarding the relation between collapse and folding, and whether intermediates are populated. In order to resolve these vexing issues, we elucidate the denaturant-dependent thermodynamics and kinetics of Ub folding at low and neutral pH as a function of Guanidinium chloride and Urea using coarse-grained molecular simulations...
January 11, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28076816/mutation-g1629e-increases-von-willebrand-factor-cleavage-via-a-cooperative-destabilization-mechanism
#11
Camilo Aponte-Santamaría, Svenja Lippok, Judith J Mittag, Tobias Obser, Reinhard Schneppenheim, Carsten Baldauf, Frauke Gräter, Ulrich Budde, Joachim O Rädler
The large multimeric glycoprotein von Willebrand Factor (VWF) plays a pivotal adhesive role during primary hemostasis. VWF is cleaved by the protease ADAMTS13 as a down-regulatory mechanism to prevent excessive VWF-mediated platelet aggregation. For each VWF monomer, the ADAMTS13 cleavage site is located deeply buried inside the VWF A2 domain. External forces in vivo or denaturants in vitro trigger the unfolding of this domain, thereby leaving the cleavage site solvent-exposed and ready for cleavage. Mutations in the VWF A2 domain, facilitating the cleavage process, cause a distinct form of von Willebrand disease (VWD), VWD type 2A...
January 10, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28075590/nanometer-sized-water-bridge-and-pull-off-force-in-afm-at-different-relative-humidities-reproducibility-measurement-and-model-based-on-surface-tension-change
#12
Miroslav Bartošík, Lukáš Kormoš, Lukáš Flajšman, Radek Kalousek, Jindřich Mach, Zuzana Lišková, David Nezval, Vojtěch Švarc, Tomáš Šamořil, Tomáš Šikola
This article deals with the analysis of the relationship between the pull-off force measured by atomic force microscopy and the dimensions of water bridge condensed between a hydrophilic silicon oxide tip and a silicon oxide surface under ambient conditions. Our experiments have shown that the pull-off force increases linearly with the radius of the tip and nonmonotonically with the relative humidity (RH). The latter dependence generally consists of an initial constant part changing to a convex-concave-like increase of the pull-off force and finally followed by a concave-like decrease of this force...
January 11, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28075555/familial-mutations-may-switch-conformational-preferences-in-%C3%AE-synuclein-fibrils
#13
Liang Xu, Buyong Ma, Ruth Nussinov, Damien Thompson
The pathogenesis of Parkinson's disease is closely associated with the aggregation of the α-synuclein protein. Several familial mutants have been identified and shown to affect the aggregation kinetics of α-synuclein through distinct molecular mechanisms. Quantitative evaluation of the relative stabilities of the wild type and mutant fibrils is crucial for understanding the aggregation process and identifying the key component steps. In this work, we examined two topologically different α-synuclein fibril structures that are either determined by solid-state NMR method or modelled based on solid-state NMR data, and characterized their conformational properties and thermodynamic stabilities using molecular dynamics simulations...
January 11, 2017: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/28075332/-i-ab-initio-i-calculations-of-the-elastic-and-thermodynamic-properties-of-gold-under-pressure
#14
Nikolai A Smirnov
The paper presents first-principles FP-LMTO calculations on the relative stability of $fcc$, $bcc$, $hcp$ and $dhcp$ gold under pressure. They were done in Local Density Approximation (LDA), as well as in Generalized Gradient Approximation (GGA) with and without spin-orbit interaction. Phonon spectra for the considered gold structures were obtained from LDA calculations within linear response theory and the contribution of lattice vibrations to the free energy of the system was determined in quasiharmonic approximation...
January 11, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28074947/predicting-the-solubility-of-mixtures-of-sugars-and-their-replacers-using-the-flory-huggins-theory
#15
R G M van der Sman
In this paper we investigate whether the Flory-Huggins theory can describe the thermodynamics of solutions of simple carbohydrates, like sugars and polyols. In particular, we focus on the description of the solubility of the carbohydrates in water. This is investigated for both binary and ternary mixtures, having two types of these carbohydrates. This research question arises especially in the case of bakery products, where one seeks to replace sucrose with other simple carbohydrates - which are often polyols...
January 11, 2017: Food & Function
https://www.readbyqxmd.com/read/28074743/synthesis-of-nanoporous-carbon-for-fast-uptake-of-cr-vi-and-ni-ii-from-aqueous-solution
#16
Imed Ghiloufi
Nanoporous carbon (NPC), based on organic xerogel compounds, was prepared at 650 ºC pyrolysis temperature by sol-gel method from pyrogallol and formaldehyde (PF-650) mixtures in water using picric acid as catalyst. The performance of NPC was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and nitrogen porosimetry. The metal uptake characteristics were explored using effective parameters including pH, contact time, initial metal ion concentration, and temperature...
January 10, 2017: Water Environment Research: a Research Publication of the Water Environment Federation
https://www.readbyqxmd.com/read/28074209/cu-i-and-ag-i-complex-formation-with-the-hydrophilic-phosphine-1-3-5-triaza-7-phosphadamantane-in-different-ionic-media-how-to-estimate-the-effect-of-a-complexing-medium
#17
Francesco Endrizzi, Plinio Di Bernardo, Pier Luigi Zanonato, Francesco Tisato, Marina Porchia, Abdirisak Ahmed Isse, Andrea Melchior, Marilena Tolazzi
The complexes of Cu(i) and Ag(i) with 1,3,5-triaza-7-phosphadamantane (PTA) are currently studied for their potential clinical use as anticancer agents, given the cytotoxicity they exhibited in vitro towards a panel of several human tumor cell lines. These metallodrugs are prepared in the form of [M(PTA)4](+) (M = Cu(+), Ag(+)) compounds and dissolved in physiological solution for their administration. However, the nature of the species involved in the cytotoxic activity of the compounds is often unknown. In the present work, the thermodynamics of formation of the complexes of Cu(i) and Ag(i) with PTA in aqueous solution is investigated by means of potentiometric, spectrophotometric and microcalorimetric methods...
January 11, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28074206/synthesis-reactivity-and-characterization-of-pt-ii-complexes-with-n-n-chelating-ligands-structure-and-dimethylsulfoxide-reactivity-relationship
#18
Konstantinos Ypsilantis, Theodoros Tsolis, Andreas Kourtellaris, Manolis J Manos, John C Plakatouras, Achilleas Garoufis
Platinum(ii) complexes of the formula PtLCl2 [L = 2-(2'-pyridyl)quinoxaline, (pqx) (1), 2,(2'-pyridyl)benzo[g]quinoxaline, (pbqx) (3) and 2,(2'-pyridyl)quinoline, (pqn) (5)] were synthesized and characterized by spectroscopic and X-ray diffraction methods. Also, monodentate coordination of the ligands pqx and pbqx formed the complexes trans-Pt(DMSO)pqxCl2 (2) and trans-Pt(DMSO)pbqxCl2 (4) as it is indicated from X-ray crystal structure and NMR studies. The reaction of the complexes (1), (3) and (5) with DMSO-d6 revealed a ligand-release solvolysis, which was studied by means of NMR techniques...
January 11, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28072536/role-of-ionic-strength-and-ph-in-modulating-thermodynamic-profiles-associated-with-co-escape-from-rice-nonsymbiotic-hemoglobin-1
#19
David Butcher, Sophie Bernad, Valerie Derrien, Pierre Sebban, Jaroslava Miksovska
Type 1 nonsymbiotic hemoglobins are found in a wide variety of land plants and exhibit very high affinities for exogenous gaseous ligands. These proteins are presumed to have a role in protecting plant cells from oxidative stress under etiolated/hypoxic conditions through NO dioxygenase activity. In this study we have employed photoacoustic calorimetry, time-resolved absorption spectroscopy, and classical molecular dynamics simulations in order to elucidate thermodynamics, kinetics, and ligand migration pathways upon CO photodissociation from WT and a H73L mutant of type 1 nonsymbiotic hemoglobin from Oryza sativa (rice)...
January 10, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28072535/a-mechanistic-study-of-the-validity-of-using-hydroxyl-radical-probes-to-characterize-electrochemical-advanced-oxidation-processes
#20
Yin Jing, Brian P Chaplin
The detection of hydroxyl radicals (OH•) is typically accomplished by using reactive probe molecules, but prior studies have not thoroughly investigated the suitability of these probes for use in electrochemical advanced oxidation processes (EAOPs), due to the neglect of alternative reaction mechanisms. In this study, we investigated the suitability of four OH• probes (coumarin, p-chlorobenzoic acid, terephthalic acid, and p-benzoquinone) for use in EAOPs. Experimental results indicated that both coumarin and p-chlorobenzoic acid are oxidized via direct electron transfer reactions, while p-benzoquinone and terephthalic acid are not...
January 10, 2017: Environmental Science & Technology
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