keyword
MENU ▼
Read by QxMD icon Read
search

Thermodynamics

keyword
https://www.readbyqxmd.com/read/28718643/correction-to-chemical-dynamic-thermodynamic-resolution-and-s-r-interconversion-of-unprotected-unnatural-tailor-made-%C3%AE-amino-acids
#1
Shuni Wang, Shengbin Zhou, Jiang Wang, Yong Nian, Aki Kawashima, Hiroki Moriwaki, José L Aceña, Vadim A Soloshonok, Hong Liu
No abstract text is available yet for this article.
July 18, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28718635/undervalued-n3-coordination-revealed-in-the-cisplatin-complex-with-2-deoxyadenosine-5-monophosphate-by-a-combined-irmpd-and-theoretical-study
#2
Barbara Chiavarino, Maria Elisa Crestoni, Simonetta Fornarini, Debora Scuderi, Jean-Yves Salpin
The complex obtained by the reaction of cisplatin and 2'-deoxyadenosine-5'-monophosphate (5'-dAMP) in water has been isolated and detected by electrospray ionization mass spectrometry. The so-formed cis-[PtCl(NH3)2(5'-dAMP)](+) complex has been studied in detail by infrared multiple photon dissociation (IRMPD) spectroscopy in two spectral ranges, namely, 700-1900 and 2800-3800 cm(-1), backed by quantum-chemical calculations at the B3LYP/LACV3P/6-311G** level of theory. In agreement with the computational results, the vibrational spectroscopic characterization of cis-[PtCl(NH3)2(5'-dAMP)](+) shows that the sampled ionic population comprises two major isomers, differentiated in the X-H stretching region by their distinct fragmentation patterns...
July 18, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28718470/co2-activation-and-dissociation-on-the-low-miller-index-surfaces-of-pure-and-ni-coated-iron-metal-a-dft-study
#3
Caroline R Kwawu, Richard Tia, Evans Adei, Nelson Y Dzade, C Richard A Catlow, Nora H de Leeuw
We have used spin polarized density functional theory calculations to perform extensive mechanistic studies of CO2 dissociation into CO and O on the clean Fe(100), (110) and (111) surfaces and on the same surfaces coated by a monolayer of nickel. CO2 chemisorbs on all three bare facets and binds more strongly to the stepped (111) surface than on the open flat (100) and close-packed (110) surfaces, with adsorption energies of -88.7 kJ mol(-1), -70.8 kJ mol(-1) and -116.8 kJ mol(-1) on the (100), (110) and (111) facets, respectively...
July 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28718281/long-distance-modulation-of-disorder-to-order-in-protein-allostery
#4
Jingheng Wang, Gregory S Custer, Dorothy Beckett, Silvina Matysiak
Elucidation of the molecular details of allosteric communication between distant sites in a protein is key to understanding and manipulating many biological regulatory processes. Although protein disorder is acknowledged to play an important thermodynamic role in allostery, the molecular mechanisms by which this disorder is harnessed for long distance communication are known for a limited number of systems. Transcription repression by the E. coli biotin repressor, BirA, is allosterically activated by binding of the small molecule effector biotinoyl-5'-AMP...
July 18, 2017: Biochemistry
https://www.readbyqxmd.com/read/28717973/design-and-development-of-repaglinide-microemulsion-gel-for-transdermal-delivery
#5
Ujwala A Shinde, Sheela H Modani, Kavita H Singh
Microemulsion formulation of repaglinide, a BCS class II hypoglycemic agent with limited oral bioavailability, was developed considering its solubility in various oils, surfactants, and cosurfactants. The pseudo-ternary phase diagrams for microemulsion regions were constructed by water titration method at K m 1:1 and characterized for optical birefringence, percentage transmittance, pH, refractive index, globule size, zeta potential, viscosity, drug content, and thermodynamic stability. To enhance the drug permeation and residence time, the optimized microemulsions having mean globule size of 36...
July 17, 2017: AAPS PharmSciTech
https://www.readbyqxmd.com/read/28717802/a-computational-study-on-the-mechanism-of-ynamide-mediated-amide-bond-formation-from-carboxylic-acids-and-amines
#6
Song-Lin Zhang, Hai-Xing Wan, Zhu-Qin Deng
This paper reports a computational study elucidating the reaction mechanism for ynamide-mediated amide bond formation from carboxylic acids and amines. The mechanisms have been studied in detail for ynamide hydrocarboxylation and the subsequent aminolysis of the resulting adduct by an amine. Ynamide hydrocarboxylation is kinetically favorable and thermodynamically irreversible, resulting in the formation of a key low-lying intermediate CP1 featuring geminal vinylic acyloxy and sulfonamide groups. The aminolysis of CP1 by the amine is proposed to be catalyzed by the carboxylic acid itself that imparts favourable bifunctional effects...
July 18, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28717162/ultra-low-threshold-polariton-lasing-at-room-temperature-in-a-gan-membrane-microcavity-with-a-zero-dimensional-trap
#7
R Jayaprakash, F G Kalaitzakis, G Christmann, K Tsagaraki, M Hocevar, B Gayral, E Monroy, N T Pelekanos
Polariton lasers are coherent light sources based on the condensation of exciton-polaritons in semiconductor microcavities, which occurs either in the kinetic or thermodynamic (Bose-Einstein) regime. Besides their fundamental interest, polariton lasers have the potential of extremely low operating thresholds. Here, we demonstrate ultra-low threshold polariton lasing at room temperature, using an all-dielectric, GaN membrane-based microcavity, with a spontaneously-formed zero-dimensional trap. The microcavity is fabricated using an innovative method, which involves photo-electrochemical etching of an InGaN sacrificial layer and allows for the incorporation of optimally-grown GaN active quantum wells inside a cavity with atomically-smooth surfaces...
July 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28716947/thermodynamic-constraint-on-the-depth-of-the-global-tropospheric-circulation
#8
David W J Thompson, Sandrine Bony, Ying Li
The troposphere is the region of the atmosphere characterized by low static stability, vigorous diabatic mixing, and widespread condensational heating in clouds. Previous research has argued that in the tropics, the upper bound on tropospheric mixing and clouds is constrained by the rapid decrease with height of the saturation water vapor pressure and hence radiative cooling by water vapor in clear-sky regions. Here the authors contend that the same basic physics play a key role in constraining the vertical structure of tropospheric mixing, tropopause temperature, and cloud-top temperature throughout the globe...
July 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28716925/symmetry-related-proton-transfer-pathways-in-respiratory-complex-i
#9
Andrea Di Luca, Ana P Gamiz-Hernandez, Ville R I Kaila
Complex I functions as the initial electron acceptor in aerobic respiratory chains of most organisms. This gigantic redox-driven enzyme employs the energy from quinone reduction to pump protons across its complete approximately 200-Å membrane domain, thermodynamically driving synthesis of ATP. Despite recently resolved structures from several species, the molecular mechanism by which complex I catalyzes this long-range proton-coupled electron transfer process, however, still remains unclear. We perform here large-scale classical and quantum molecular simulations to study the function of the proton pump in complex I from Thermus thermophilus The simulations suggest that proton channels are established at symmetry-related locations in four subunits of the membrane domain...
July 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28715635/redox-potentials-from-ab-initio-molecular-dynamics-and-explicit-entropy-calculations-application-to-transition-metals-in-aqueous-solution
#10
Miguel A Caro, Olga Lopez-Acevedo, Tomi Laurila
We present a complete methodology to consistently estimate redox potentials strictly from first principles, without any experimental input. The methodology is based on (i) ab initio molecular dynamics (MD) simulations, (ii) all-atom explicit solvation, (iii) the two-phase thermodynamic (2PT) model and (iv) the use of electrostatic potentials as references for the absolute electrochemical scale. We apply the approach presented to compute reduction potentials of the following redox couples: Cr(+2/+3), V(+2/+3), Ru(NH3)6(+2/+3), Sn(+2/+4), Cu(+1/+2), FcMeOH(0/+1) and Fe(+2/+3) (in aqueous solution) and Fc(0/+1) (in acetonitrile)...
July 17, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28715438/a-sequence-level-model-of-an-intact-locus-predicts-the-location-and-function-of-nonadditive-enhancers
#11
Kenneth A Barr, John Reinitz
Metazoan gene expression is controlled through the action of long stretches of noncoding DNA that contain enhancers-shorter sequences responsible for controlling a single aspect of a gene's expression pattern. Models built on thermodynamics have shown how enhancers interpret protein concentration in order to determine specific levels of gene expression, but the emergent regulatory logic of a complete regulatory locus shows qualitative and quantitative differences from isolated enhancers. Such differences may arise from steric competition limiting the quantity of DNA that can simultaneously influence the transcription machinery...
2017: PloS One
https://www.readbyqxmd.com/read/28715212/kinetics-of-electrophilic-alkylations-of-barbiturate-and-thiobarbiturate-anions
#12
Alexander Schade, Ivan Tchernook, Mirko Bauer, Alexander Oehlke, Martin Breugst, Joachim Friedrich, Stefan Spange
Second-order rate constants (k2) of the reactions of various barbiturate anions such as the parent barbiturate, 1,3-dimethylbarbiturate, 2-thiobarbiturate, and 1,3-diethyl-2-thiobarbiturate with diarylcarbenium ions and Michael acceptors have been determined in dimethylsulfoxide solution at 20 °C. The reactivity parameters N and sN of the barbiturate anions were derived from the linear plots of log k2 versus the electrophilicity parameters E of these reference electrophiles, according to the linear-free-energy relationship log k2 (20 °C) = sN (E+N)...
July 17, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28715184/theoretical-investigation-of-c-h-vibrational-spectroscopy-i-modeling-of-methyl-and-methylene-groups-of-ethanol-with-different-conformers
#13
Lin Wang, Tatsuya Ishiyama, Akihiro Morita
A flexible and polarizable molecular model of ethanol is developed to extend our investigation of thermodynamic, structural and vibrational properties of liquid and interface. Molecular dynamics (MD) simulation with the present model confirmed that this model well reproduces a number of properties of liquid ethanol, including density, heat of vaporization, surface tension, molecular dipole moment, and trans/gauche ratio. In particular, the present model can describe vibrational IR, Raman and sum frequency generation (SFG) spectra of ethanol and partially deuterated analogues with reliable accuracy...
July 17, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28715019/thermodynamic-integration-network-study-of-electron-transfer-from-proteins-to-aggregates
#14
Sehee Na, Anna Bauß, Michael Langenmaier, Thorsten Koslowski
We describe electron transfer through the NrfHA nitrite reductase heterodimer using a thermodynamic integration scheme based upon molecular dynamics simulations. From the simulation data, we estimate two of the characteristic energies of electron transfer, the thermodynamic driving forces, ΔG, and the reorganization energies, λ. Using a thermodynamic network analysis, the statistical accuracy of the ΔG values can be enhanced significantly. Although the reaction free energies and activation barriers are hardly affected by protein aggregation, the complete reaction mechanism only emerges from the simulations of the dimer rather than focussing on the individual protein chains: it involves an equienergetic transprotein element of electron storage and conductivity...
July 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28714983/tunable-room-temperature-magnetic-skyrmions-in-ir-fe-co-pt-multilayers
#15
Anjan Soumyanarayanan, M Raju, A L Gonzalez Oyarce, Anthony K C Tan, Mi-Young Im, A P Petrović, Pin Ho, K H Khoo, M Tran, C K Gan, F Ernult, C Panagopoulos
Magnetic skyrmions are nanoscale topological spin structures offering great promise for next-generation information storage technologies. The recent discovery of sub-100-nm room-temperature (RT) skyrmions in several multilayer films has triggered vigorous efforts to modulate their physical properties for their use in devices. Here we present a tunable RT skyrmion platform based on multilayer stacks of Ir/Fe/Co/Pt, which we study using X-ray microscopy, magnetic force microscopy and Hall transport techniques...
July 17, 2017: Nature Materials
https://www.readbyqxmd.com/read/28714684/the-surface-of-protein-%C3%AE-6-85-can-act-as-a-template-for-recurring-peg-structure
#16
Shu-Han Chao, Jan Schaefer, Martin Gruebele
PEGylated proteins play an increasingly important role in pharmaceutical drug delivery. We recently showed that short PEG chains can affect protein structure, even when they are not making extensive contact with the protein surface. In contrast, PEG is generally assumed to form a relatively unstructured coil, whose compactness depends on solvent conditions. Here we test whether a host protein could allow PEG to form recurrent structural motifs while the PEG chain is in contact with the protein surface. We link a PEG oligomer (n=45) to one of two nearly opposite locations on the small alpha-helical protein 6-85 to investigate this question...
July 17, 2017: Biochemistry
https://www.readbyqxmd.com/read/28714668/self-registered-self-assembly-of-block-copolymers
#17
Lei Wan, Ricardo Ruiz, He Gao, Thomas R Albrecht
Directed self-assembly (DSA) of block copolymer (BCP) thin films, especially with density multiplication, is one of the most promising options for further improving resolution and throughput in nanolithography. However, controlling defect density has been one of the major hurdles for many DSA applications. Both thermodynamically and kinetically, defect-free patterns favor the use of low density multiplication factors and thinner films, which undermine the promise of enhanced resolution and the formation of robust masks for pattern transfer...
July 17, 2017: ACS Nano
https://www.readbyqxmd.com/read/28714536/the-evaluation-of-acute-toxicity-antimicrobial-activity-of-1-phenyl-5-p-tolyl-1h-1-2-3-triazole-and-binding-to-human-serum-albumin
#18
Hong-Ye Duan, Jian-Ling Li, Lu-Yong Wu, Huo-Ming Shu, Yu-Xue Chen, Guo-Hua Ding, Run-Cong Dong, Hong-Zong Si, Xia Zhong, Wen-Ying He
1-Phenyl-5-p-tolyl-1H-1, 2, 3-triazole (PPTA) was a synthesized compound. The result of acute toxicities to mice of PPTA by intragastric administration indicated that PPTA did not produce any significant acute toxic effect on Kunming strain mice. It exhibited the various potent inhibitory activities against two kinds of bananas pathogenic bacteria, black sigatoka and freckle, when compared with that of control drugs and the inhibitory rates were up to 64.14% and 43.46%, respectively, with the same concentration of 7...
July 17, 2017: Journal of Biochemical and Molecular Toxicology
https://www.readbyqxmd.com/read/28714505/the-antiproliferative-activity-of-di-2-pyridylketone-dithiocarbamate-is-partly-attributed-to-catalase-inhibition-detailing-the-interaction-by-spectroscopic-methods
#19
Cuiping Li, Youxun Liu, Yun Fu, Tengfei Huang, Lixia Kang, Changzheng Li
The bioactivity of drugs is attributed to their interaction with biological molecules, embodied in either their direct or indirect influence on enzyme activity and conformation. Di-2-pyridylketone hydrazine dithiocarbamate (DpdtC) exhibits significant antitumor activity in our preliminary study. We speculated that its activity may partly stem from enzyme inhibition due to strong metal chelating ability. To this end, we assessed its effect on catalase from erythrocytes and found evidence of inhibition, which was further confirmed by ROS determination in vivo...
July 17, 2017: Molecular BioSystems
https://www.readbyqxmd.com/read/28711712/ex-vivo-and-in-vivo-evaluation-of-microemulsion-based-transdermal-delivery-of-e-coli-specific-t4-bacteriophage-a-rationale-approach-to-treat-bacterial-infection
#20
Vaibhav Rastogi, Pragya Yadav, Anurag Verma, Jayanta K Pandit
This study is focused on the development and evaluation of transdermal delivery of E. coli-specific T4 bacteriophages both ex-vivo and in-vivo using microemulsion as delivery carrier in eradicating the infection caused by E. coli. Microemulsions were prepared by mixing selected oil, surfactants and aqueous phase containing bacteriophages. The formulations were subjected to physicochemical characterization, ex-vivo and in-vivo permeation, stability studies, histological and immunofluorescence examination. The colloidal system exhibits a uniform size distribution, of finite size (150-320nm)...
July 12, 2017: European Journal of Pharmaceutical Sciences
keyword
keyword
92038
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"