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https://www.readbyqxmd.com/read/29227957/synergistic-cytotoxicity-and-mechanism-of-caffeine-and-lysozyme-on-hepatoma-cell-line-hepg2
#1
Hongchao Yang, Jingjuan Li, Lin Cui, Yanqing Ren, Liying Niu, Xinguo Wang, Yun Huang, Lijian Cui
The influences of caffeine, lysozyme and the joint application of them on the hepatoma cell line HepG2 proliferation inhibition and cell apoptosis were observed by 3-(4, 5-dimethyl-2-thiazyl)-2, 5-diphenyl-2H-tetrazolium bromide assay and Hoechst 33342, which showed the proliferation inhibition rate of the joint application on HepG2 cells was 47.21%, significantly higher than caffeine or lysozyme, and the joint application promoted the apoptosis of HepG2 cells obviously. Van't Hoff classical thermodynamics formula, the Föster theory of non-radiation energy transfer and fluorescence phase diagram were used to manifest that the process of lysozyme binding to caffeine followed a two-state model, which was spontaneous at low temperature driven by enthalpy change, and the predominant intermolecular force was hydrogen bonding or Van der Waals force to stabilize caffeine-lysozyme complex with the distance 5...
December 6, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29227560/enhancing-van-der-waals-interactions-of-non-polar-adsorbates-with-functionalized-uio-66-the-unique-effect-of-para-hydroxyl-groups
#2
Trenton Tovar, Ivan Iordanov, Dorina Sava Gallis, Jared Bernard DeCoste
For small, nonpolar adsorbates, physisorption is dominated by weak Van der Waals interactions limiting the adsorption capacity. A common strategy to enhance the adsorption properties of isoreticular metal-organic framework (MOFs), such as UiO-66, is to add functional groups to the organic linker. Low and high pressure O2 isotherms were measured on UiO-66 MOFs functionalized with electron donating and withdrawing groups. It was found that the electron donating effects of -NH2, -OH, and -OCF3 groups enhance the uptake of O2...
December 11, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29226924/analysis-of-the-conformational-properties-of-amine-ligands-at-the-gold-water-interface-with-qm-mm-and-qm-mm-simulations
#3
Dongyue Liang, Jiewei Hong, Dong Fang, Joseph W Bennett, Sara E Mason, Robert J Hamers, Qiang Cui
We describe a strategy of integrating quantum mechanical (QM), hybrid quantum mechanical/molecular mechanical (QM/MM) and MM simulations to analyze the physical properties of a solid/water interface. This protocol involves using a correlated ab initio (CCSD(T)) method to first calibrate Density Functional Theory (DFT) as the QM approach, which is then used in QM/MM simulations to compute relevant free energy quantities at the solid/water interface using a mean-field approximation of Yang et al. that decouples QM and MM thermal fluctuations; gas-phase QM/MM and periodic DFT calculations are used to determine the proper QM size in the QM/MM simulations...
December 11, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29226394/3d-mesoporous-van-der-waals-heterostructures-for-trifunctional-energy-electrocatalysis
#4
Cheng Tang, Ling Zhong, Bingsen Zhang, Hao-Fan Wang, Qiang Zhang
The emergence of van der Waals (vdW) heterostructures of 2D materials has opened new avenues for fundamental scientific research and technological applications. However, the current concepts and strategies of material engineering lack feasibilities to comprehensively regulate the as-obtained extrinsic physicochemical characters together with intrinsic properties and activities for optimal performances. A 3D mesoporous vdW heterostructure of graphene and nitrogen-doped MoS2 via a two-step sequential chemical vapor deposition method is constructed...
December 11, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29226291/attractive-non-dlvo-forces-induced-by-adsorption-of-monovalent-organic-ions
#5
Alexander M Smith, Plinio Maroni, Michal Borkovec
Direct force measurements between negatively charged colloidal particles were carried out using an atomic force microscope (AFM) in aqueous solutions containing monovalent organic cations, namely tetraphenylarsonium (Ph4As+), 1-hexyl-3-methylimidazolium (HMIM+), and 1-octyl-3-methylimidazolium (OMIM+). These ions adsorb to the particle surface, and induce a charge reversal. The forces become attractive at the charge neutralization point, but they are stronger than van der Waals forces. This additional and unexpected attraction decays exponentially with a decay length of a few nanometers, and is strikingly similar to the one previously observed in the presence of multivalent ions...
December 11, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29221413/heterogeneous-nucleation-on-rough-surfaces-generalized-gibbs-approach
#6
Alexander S Abyzov, Jürn W P Schmelzer, Leonid N Davydov
Heterogeneous nucleation (condensation) of liquid droplets from vapor (gas) on a defective solid surface is considered. The vapor is described by the van der Waals equation of state. The dependence of nucleating droplet parameters on droplet size is accounted for within the generalized Gibbs approach. As a surface defect, a conic void is taken. This choice allows us to simplify the analysis and at the same time to follow the main aspects of the influence of the surface roughness on the nucleation process. Similar to condensation on ideal planar surfaces, the contact angle and catalytic factor for heterogeneous nucleation on a rough surface depend on the degree of vapor overcooling...
December 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29221408/exploring-a-multi-scale-method-for-molecular-simulation-in-continuum-solvent-model-explicit-simulation-of-continuum-solvent-as-an-incompressible-fluid
#7
Li Xiao, Ray Luo
We explored a multi-scale algorithm for the Poisson-Boltzmann continuum solvent model for more robust simulations of biomolecules. In this method, the continuum solvent/solute interface is explicitly simulated with a numerical fluid dynamics procedure, which is tightly coupled to the solute molecular dynamics simulation. There are multiple benefits to adopt such a strategy as presented below. At this stage of the development, only nonelectrostatic interactions, i.e., van der Waals and hydrophobic interactions, are included in the algorithm to assess the quality of the solvent-solute interface generated by the new method...
December 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29221389/nuclear-spin-parity-dependent-spectroscopy-and-predissociation-dynamics-in-voh-2-%C3%A2-0-overtone-excited-ne-h2o-clusters-theory-and-experiment
#8
Michael P Ziemkiewicz, Christian Pluetzer, Jérôme Loreau, Ad van der Avoird, David J Nesbitt
Vibrationally state selective overtone spectroscopy and state- and nuclear spin-dependent predissociation dynamics of weakly bound ortho- and para-Ne-H2O complexes (D0(ortho) = 34.66 cm-1 and D0(para) = 31.67 cm-1) are reported, based on near-infrared excitation of van der Waals cluster bands correlating with vOH = 2 ← 0 overtone transitions (|02-〉 and |02+〉) out of the ortho (101) and para (000) internal rotor states of the H2O moiety. Quantum theoretical calculations for nuclear motion on a high level potential energy surface [CCSD(T)/VnZf12 (n = 3, 4)], corrected for basis set superposition error and extrapolated to the complete basis set (CBS) limit, are employed to successfully predict and assign Π-Σ, Σ-Σ, and Σ-Π infrared bands in the spectra, where Σ or Π represent approximate projections of the body-fixed H2O angular momentum along the Ne-H2O internuclear axis...
December 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29219374/band-structure-and-contact-resistance-of-carbon-nanotubes-deformed-by-a-metal-contact
#9
Roohollah Hafizi, Jerry Tersoff, Vasili Perebeinos
Capillary and van der Waals forces cause nanotubes to deform or even collapse under metal contacts. Using ab initio band structure calculations, we find that these deformations reduce the band gap by as much as 30%, while fully collapsed nanotubes become metallic. Moreover, degeneracy lifting due to the broken axial symmetry, and wave functions mismatch between the fully collapsed and the round portions of a CNT, lead to a 3 times higher contact resistance. The latter we demonstrate by contact resistance calculations within the tight-binding approach...
November 17, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29219304/van-der-waals-layered-materials-opportunities-and-challenges
#10
Dinh Loc Duong, Seok Joon Yun, Young Hee Lee
Since graphene became available by a scotch tape, a vast class of two-dimensional (2D) van der Waals (vdW) layered materials has been researched intensively. What is more intriguing is that the well-known physics and chemistry of three-dimensional bulk materials are often irrelevant, revealing exotic phenomena in 2D vdW materials. By further constructing heterostructures of these materials in the planar and vertical directions, which can be easily achieved via simple exfoliation techniques, numerous quantum mechanical devices have been demonstrated for fundamental research and technological applications...
December 8, 2017: ACS Nano
https://www.readbyqxmd.com/read/29217181/enhancement-of-intrinsic-fluorescence-of-human-carbonic-anhydrase-ii-upon-topiramate-binding-some-evidence-for-drug-induced-molecular-contraction-of-the-protein
#11
Sirous Ghobadi, Mohammad Reza Ashrafi-Kooshk, Hamid Mahdiuni, Reza Khodarahmi
In this report, the effect of topiramate (TPM), an anticonvulsant sulfamate drug, on the structure of human carbonic anhydrase II (hCA II) was investigated by spectroscopic techniques. The intrinsic fluorescence experiments indicated that TPM binding causes enhancement of enzyme fluorescence via decreasing the internal quenching and energy transfer efficiency, the result supported by molecular dynamics simulation. Thermodynamic analysis of the binding process suggested that hydrogen bonding and van der Waals interactions are the major forces in the interaction of TPM with hCA II...
December 4, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29216575/tuning-the-schottky-rectification-in-graphene-hexagonal-boron-nitride-molybdenum-disulfide-heterostructure
#12
Biao Liu, Yu-Qing Zhao, Zhuo-Liang Yu, Lin-Zhi Wang, Meng-Qiu Cai
It was still a great challenge to design high performance of rectification characteristic for the rectifier diode. Lately, a new approach was proposed experimentally to tune the Schottky barrier height (SBH) by inserting an ultrathin insulated tunneling layer to form metal-insulator-semiconductor (MIS) heterostructures. However, the electronic properties touching off the high performance of these heterostructures and the possibility of designing more efficient applications for the rectifier diode were not presently clear...
December 4, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29215171/graphene-inks-as-versatile-templates-for-printing-tiled-metal-oxide-crystalline-films
#13
Muchun Liu, Po-Yen Chen, Robert H Hurt
There is great interest in exploiting van der Waals gaps in layered materials as confinement reaction vessels to template the synthesis of new nanosheet structures. The gallery spaces in multilayer graphene oxide, for example, can intercalate hydrated metal ions that assemble into metal oxide films during thermal oxidation of the sacrificial graphene template. This approach offers limited control of structure, however, and does not typically lead to 2D atomic-scale growth of anisotropic platelet crystals, but rather arrays of simple particles directionally sintered into porous sheets...
December 7, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29212044/multi-spectroscopic-and-molecular-docking-studies-on-the-interaction-of-darunavir-a-hiv-protease-inhibitor-with-calf-thymus-dna
#14
Jie-Hua Shi, Kai-Li Zhou, Yan-Yue Lou, Dong-Qi Pan
Molecular interaction of darunavir (DRV), a HIV protease inhibitor with calf thymus deoxyribonucleic acid (ct-DNA) was studied in physiological buffer (pH7.4) by multi-spectroscopic approaches hand in hand with viscosity measurements and molecular docking technique. The UV absorption and fluorescence results together revealed the formation of a DRV-ct-DNA complex having binding affinities of the order of 103M-1, which was more in keeping with the groove binding. The results that DRV bound to ct-DNA via groove binding mode was further evidenced by KI quenching studies, viscosity measurements, competitive binding investigations with EB and Rhodamine B and CD spectral analysis...
November 29, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29211469/machine-learning-of-dynamic-electron-correlation-energies-from-topological-atoms
#15
James L McDonagh, Arnaldo F Silva, Mark A Vincent, Paul L A Popelier
We present an innovative method for predicting the dynamic electron correlation energy of an atom or a bond in a molecule utilizing topological atoms. Our approach uses the machine learning method Kriging (Gaussian Process Regression with a non-zero mean function) to predict these dynamic electron correlation energy contributions. The true energy values are calculated by partitioning the MP2 two-particle density-matrix via the Interacting Quantum Atoms (IQA) procedure. To our knowledge, this is the first time such energies have been predicted by a machine learning technique...
December 6, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/29211077/self-cleaning-by-harnessing-wrinkles-in-two-dimensional-layered-crystals
#16
Jia-Sheng Sun, Jin-Wu Jiang, Harold S Park, Sulin Zhang
Two-dimensional (2D) layered crystals are prone to bending and folding owing to their ultra-low bending stiffness. Folds are traditionally viewed as defects that degrade the material performance. Here, we demonstrate that folds and cohesive forces in 2D layered crystals like graphene and MoS2 can be exploited to collect and clean up interlayer impurities, wherein multiple separated impurities agglomerate into a single, large cluster. We combine classical molecular dynamics simulations and an analytical model to elucidate the competing roles of membrane bending and impurity-membrane cohesive energies in the self-cleaning process...
December 6, 2017: Nanoscale
https://www.readbyqxmd.com/read/29210400/h-bn-graphene-van-der-waals-vertical-heterostructure-a-fully-spin-polarized-photocurrent-generator
#17
Xixi Tao, Lei Zhang, Xiaohong Zheng, Hua Hao, Xianlong Wang, Lingling Song, Zhi Zeng, Hong Guo
By constructing transport junctions using graphene-based van der Waals (vdW) heterostructures in which a zigzag-edged graphene nanoribbon (ZGNR) is sandwiched between two hexagonal boron-nitride sheets, we computationally demonstrate a new scheme for generating perfect spin-polarized quantum transport in ZGNRs by light irradiation. The mechanism lies in the lift of spin degeneracy of ZGNR induced by the stagger potential it receives from the BN sheets and the subsequent possibility of single spin excitation of electrons from the valence band to the conduction band by properly tuning the photon energy...
December 6, 2017: Nanoscale
https://www.readbyqxmd.com/read/29210157/electronic-properties-of-h-bcn-blue-phosphorene-van-der-waals-heterostructures
#18
Thanayut Kaewmaraya, Pornjuk Srepusharawoot, Tanveer Hussian, Vittaya Amornkitbamrung
Van der Waals heterostructures (vdWHs), a new class of materials made of a vertically selective assembly of various 2D monolayers held together by vdW forces, have attracted a great deal of attention due to their premise to design novel electronic and optoelectronic properties which is not achievable by individual 2D crystals. Using the density functional theory (DFT), we have revealed that vdWH composed of monolayers of h-BN and the latest blue phosphorus (blue phosphorene, BlueP) forms straddling type-I band offset where the band edges exclusively belong to BlueP...
December 5, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29210128/one-pot-synthesis-and-characterization-cdte-zn2-quantum-dots-and-its-molecular-interaction-with-calf-thymus-dna
#19
Cheng-Zhang Yang, Lin-Yi Li, Xiao-Han Wang, Si-Qian Yu, Yan-Jun Hu
Tremendous research efforts have been dedicated to fabricating high-quality Zn-doped CdTe quantum dots (QDs) for any potential biomedical applications. In particular, the correlation of issues regarding how QDs interact with DNA is of greatest importance. Herein, a pH-responsive study of the interactions between CdTe:Zn2+ quantum dots with 4 different sizes and calf thymus DNA (ctDNA) was conducted using multispectroscopic techniques and electrochemical investigation. Fluorescence studies revealed that this interaction process is predominantly a static process and groove binding was the main binding mode for CdTe:Zn2+ QDs to ctDNA...
December 6, 2017: Journal of Molecular Recognition: JMR
https://www.readbyqxmd.com/read/29207349/chemically-functionalized-graphene-for-lubricant-applications-microscopic-and-spectroscopic-studies-of-contact-interfaces-to-probe-the-role-of-graphene-for-enhanced-tribo-performance
#20
Ajay Chouhan, Harshal P Mungse, Om P Sharma, Raj K Singh, Om P Khatri
Shear-induced transfer of graphene on the contact interfaces was studied by microscopic and spectroscopic analyses of steel balls lubricated with chemically functionalized graphene-based mineral lube base oil (SN-150). The 3,5-di-tert-butyl-4-hydroxybenzaldehyde (DtBHBA) grafted-graphene (Gr-DtBHBA) was prepared by two-steps approach using graphene oxide as a precursor. Chemical and structural features of Gr-DtBHBA are probed by FTIR, XPS, Raman, TGA, and HRTEM analyses. The van der Waals interaction between the tertiary-butyl group in the Gr-DtBHBA and hydrocarbon chains of mineral lube base oil facilitates the dispersion of Gr-DtBHBA in the SN-150 lube base oil, which is very important for the optimized performance of Gr-DtBHBA as a lubricant additive...
December 2, 2017: Journal of Colloid and Interface Science
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