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https://www.readbyqxmd.com/read/29045784/metal-dependence-of-xylose-isomerase-from-piromyces-sp-e2-explored-by-activity-profiling-and-protein-crystallography
#1
Misun Lee, Henriette J Rozeboom, Paul de Waal, Rene de Jong, Hanna M Dudek, Dick B Janssen
Xylose isomerase from Piromyces sp. E2 (PirXI) can be used for equipping Saccharomyces cerevisiae with the capacity to ferment xylose to ethanol. The biochemical properties and structure of the enzyme have not been described even though its metal content, catalytic parameters and expression level are critical for rapid xylose utilization. We have isolated the enzyme after high-level expression in E. coli, analyzed the metal-dependence of its catalytic properties and solved twelve crystal structures in the presence of different metals, substrates, and substrate analogs...
October 18, 2017: Biochemistry
https://www.readbyqxmd.com/read/29045642/patient-and-tumor-characteristics-and-their-influence-on-early-therapy-persistence-with-letrozole-in-postmenopausal-patients-with-early-breast-cancer
#2
N Nabieva, S Kellner, T Fehm, L Häberle, J de Waal, M Rezai, B Baier, G Baake, H-C Kolberg, M Guggenberger, M Warm, N Harbeck, R Wuerstlein, J-U Deuker, P Dall, B Richter, G Wachsmann, C Brucker, J W Siebers, N Fersis, T Kuhn, C Wolf, H-W Vollert, G-P Breitbach, W Janni, R Landthaler, A Kohls, D Rezek, T Noesselt, G Fischer, S Henschen, T Praetz, V Heyl, T Kühn, T Krauss, C Thomssen, A Hohn, H Tesch, C Mundhenke, A Hein, C Rauh, C M Bayer, A Jacob, K Schmidt, E Belleville, S Y Brucker, S Kümmel, M W Beckmann, D Wallwiener, P Hadji, P A Fasching
Background: Patients' compliance and persistence with endocrine treatment has a significant effect on the prognosis in early breast cancer (EBC). The purpose of this analysis was to identify possible reasons for non-persistence, defined as premature cessation of therapy, on the basis of patient and tumor characteristics in individuals receiving adjuvant treatment with letrozole. Patients and methods: The EvAluate-TM Study is a prospective, multicenter, noninterventional study in which treatment with the aromatase inhibitor letrozole was evaluated in postmenopausal women with hormone receptor-positive EBC in the early therapy phase...
October 10, 2017: Annals of Oncology: Official Journal of the European Society for Medical Oncology
https://www.readbyqxmd.com/read/29045121/wafer-scale-synthesis-of-semiconducting-sno-monolayers-from-interfacial-oxide-layers-of-metallic-liquid-tin
#3
Torben Daeneke, Paul Atkin, Rebecca Orrell-Trigg, Ali Zavabeti, Taimur Ahmed, Sumeet Walia, Maning Liu, Yasuhiro Tachibana, Maria Javaid, Andrew D Greentree, Salvy P Russo, Richard B Kaner, Kourosh Kalantar-Zadeh
Atomically thin semiconductors are one of the fastest growing categories in materials science due to their promise to enable high-performance electronic and optical devices. Furthermore, a host of intriguing phenomena have been reported to occur when a semiconductor is confined within two dimensions. However, the synthesis of large area atomically thin materials remains as a significant technological challenge. Here we report a method that allows harvesting monolayer of semiconducting stannous oxide nanosheets (SnO) from the interfacial oxide layer of liquid tin...
October 18, 2017: ACS Nano
https://www.readbyqxmd.com/read/29044833/lateral-graphene-contacted-vertically-stacked-ws2-mos2-hybrid-photodetectors-with-large-gain
#4
Haijie Tan, Wenshuo Xu, Yuewen Sheng, Chit Siong Lau, Ye Fan, Qu Chen, Martin Tweedie, Xiaochen Wang, Yingqiu Zhou, Jamie H Warner
A demonstration is presented of how significant improvements in all-2D photodetectors can be achieved by exploiting the type-II band alignment of vertically stacked WS2 /MoS2 semiconducting heterobilayers and finite density of states of graphene electrodes. The photoresponsivity of WS2 /MoS2 heterobilayer devices is increased by more than an order of magnitude compared to homobilayer devices and two orders of magnitude compared to monolayer devices of WS2 and MoS2 , reaching 10(3) A W(-1) under an illumination power density of 1...
October 17, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29043810/structure-and-thermodynamics-of-metal-clusters-on-atomically-smooth-substrates
#5
Marco Eckhoff, Dmitri Schebarchov, David J Wales
We analyse the structure of model Ni$_{N}$ and Cu$_{N}$ clusters ($N=55$, $147$) supported on a variety of atomically smooth van der Waals surfaces. The global minima are mapped in the space of two parameters: (i) the laterally averaged surface stickiness, $\gamma$, which controls the macroscopic wetting angle; and (ii) the surface microstructure, which produces more subtle but important templating via epitaxial stresses. We find that adjusting the substrate lattice (even at constant $gamma$) can favour different crystal plane orientations in the cluster, stabilise hexagonal close-packed order, or induce various defects, such as stacking faults, twin boundaries, and fivefold disclinations...
October 18, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29042545/gate-controlled-reversible-rectifying-behaviour-in-tunnel-contacted-atomically-thin-mos2-transistor
#6
Xiao-Xi Li, Zhi-Qiang Fan, Pei-Zhi Liu, Mao-Lin Chen, Xin Liu, Chuan-Kun Jia, Dong-Ming Sun, Xiang-Wei Jiang, Zheng Han, Vincent Bouchiat, Jun-Jie Guo, Jian-Hao Chen, Zhi-Dong Zhang
Atomically thin two-dimensional semiconducting materials integrated into van der Waals heterostructures have enabled architectures that hold great promise for next generation nanoelectronics. However, challenges still remain to enable their applications as compliant materials for integration in logic devices. Here, we devise a reverted stacking technique to intercalate a wrinkle-free boron nitride tunnel layer between MoS2 channel and source drain electrodes. Vertical tunnelling of electrons therefore makes it possible to suppress the Schottky barriers and Fermi level pinning, leading to homogeneous gate-control of the channel chemical potential across the bandgap edges...
October 17, 2017: Nature Communications
https://www.readbyqxmd.com/read/29042509/properties-of-real-metallic-surfaces-effects-of-density-functional-semilocality-and-van-der-waals-nonlocality
#7
Abhirup Patra, Jefferson E Bates, Jianwei Sun, John P Perdew
We have computed the surface energies, work functions, and interlayer surface relaxations of clean (111), (100), and (110) surfaces of Al, Cu, Ru, Rh, Pd, Ag, Pt, and Au. We interpret the surface energy from liquid metal measurements as the mean of the solid-state surface energies over these three lowest-index crystal faces. We compare experimental (and random phase approximation) reference values to those of a family of nonempirical semilocal density functionals, from the basic local density approximation (LDA) to our most advanced general purpose meta-generalized gradient approximation, strongly constrained and appropriately normed (SCAN)...
October 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29039736/a-novel-central-nervous-system-penetrating-protease-inhibitor-overcomes-human-immunodeficiency-virus-1-resistance-with-unprecedented-am-to-pm-potency
#8
Manabu Aoki, Hironori Hayashi, Kalapala Venkateswara Rao, Debananda Das, Nobuyo Higashi-Kuwata, Haydar Bulut, Hiromi Aoki-Ogata, Yuki Takamatsu, Ravikiran S Yedidi, David A Davis, Shin-Ichiro Hattori, Noriko Nishida, Kazuya Hasegawa, Nobutoki Takamune, Prasanth R Nyalapatla, Heather L Osswald, Hirofumi Jono, Hideyuki Saito, Robert Yarchoan, Shogo Misumi, Arun K Ghosh, Hiroaki Mitsuya
Antiretroviral therapy for HIV-1 infection/AIDS has significantly extended the life expectancy of HIV-1-infected individuals and reduced HIV-1 transmission at very high rates. However, certain individuals who initially achieve viral suppression to undetectable levels may eventually suffer treatment failure mainly due to adverse effects and the emergence of drug-resistant HIV-1 variants. Here, we report GRL-142, a novel HIV-1 protease inhibitor containing an unprecedented 6-5-5-ring-fused crown-like tetrahydropyranofuran, which has extremely potent activity against all HIV-1 strains examined with IC50 values of attomolar-to-picomolar concentrations, virtually no effects on cellular growth, extremely high genetic barrier against the emergence of drug-resistant variants, and favorable intracellular and central nervous system penetration...
October 17, 2017: ELife
https://www.readbyqxmd.com/read/29034911/collision-cross-sections-and-ion-structures-development-of-a-general-calculation-method-via-high-quality-ion-mobility-measurements-and-theoretical-modeling
#9
Jong Wha Lee, Kimberly L Davidson, Matthew F Bush, Hugh I Kim
Ion mobility mass spectrometry (IM-MS) has become an important tool for the structural investigation of ions in the gas phase. Accurate theoretical evaluation of ion collision cross sections (CCSs) is essential for the effective application of IM-MS in structural studies. However, current theoretical tools have limitations in accurately describing a broad range of ions from small molecules to macromolecules. Significant difficulties in developing theoretical tools for CCS calculations are associated with obtaining high-quality experimental data and molecular models...
October 16, 2017: Analyst
https://www.readbyqxmd.com/read/29031273/post-transition-state-dynamics-and-product-energy-partitioning-following-thermal-excitation-of-the-f%C3%A2-hch2cn-transition-state-disagreement-with-experiment
#10
Subha Pratihar, Xinyou Ma, Jing Xie, Rebecca Scott, Eric Gao, Branko Ruscic, Adelia J A Aquino, Donald W Setser, William L Hase
Born-Oppenheimer direct dynamics simulations were performed to study atomistic details of the F + CH3CN → HF + CH2CN H-atom abstraction reaction. The simulation trajectories were calculated with a combined M06-2X/MP2 algorithm utilizing the 6-311++G** basis set. The experiments were performed at 300 K, and assuming the accuracy of transition state theory (TST), the trajectories were initiated at the F⋯HCH2CN abstraction TS with a 300 K Boltzmann distribution of energy and directed towards products. Recrossing of the TS was negligible, confirming the accuracy of TST...
October 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29031074/synthesis-antiproliferative-anti-tubulin-activity-and-docking-study-of-new-1-2-4-triazoles-as-potential-combretastatin-analogues
#11
Muhamad Mustafa, Dalia Abdelhamid, ElShimaa M N Abdelhafez, Mahmoud A A Ibrahim, Amira M Gamal-Eldeen, Omar M Aly
Combretastatin A4 (CA4) is a natural product characterized by a powerful inhibition of tubulin polymerization and a potential anticancer activity. However, therapeutic application of CA4 is substantially hindered due to geometric isomerization. In the current study, new cis-restricted Combretastatin A4 analogues containing 1,2,4-triazle in place of the olefinic bond were designed and synthesized. The synthesized compounds were evaluated for their in vitro antiproliferative activity in human hepatocellular carcinoma HepG2 and leukemia HL-60 cell lines using MTT assay...
September 28, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/29028604/new-zinc-ii-n4-tetradentate-schiff-base-complex-a-potential-cytotoxic-metallodrug-and-simple-precursor-for-the-preparation-of-zno-nanoparticles
#12
Somaye Shahraki, Ali Heydari
A novel Schiff base Zn(II) complex using a tetradentate Schiff base ligand was synthesized and characterized. The results of cytotoxicity assay revealed that the prepared complex induced cytotoxicity in a breast cancer cell line. Thus, the binding of the Zn(II) complex to human serum albumin (HSA) was investigated using spectroscopic and molecular docking methods. The fluorescence data showed that the Zn(II) complex quenched protein fluorescence by a static quenching mechanism. The binding constant (Kb), number of binding sites (n), and thermodynamic parameters were calculated and showed that the Zn(II) complex binds to HSA through hydrogen bond and Vander Waals interactions with one binding site...
October 8, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29028318/a-combination-of-c%C3%AE-h-hydrogen-bonds-and-van-der-waals-packing-modulates-the-stability-of-gxxxg-mediated-dimers-in-membranes
#13
Samantha M Anderson, Benjamin Keymar Mueller, Evan Lange, Alessandro Senes
The GxxxG motif is frequently found at the dimerization interface of a transmembrane structural motif called GASright, which is characterized by a short inter-helical distance and a right-handed crossing angle between the helices. In GASright dimers - such as glycophorin A (GpA), BNIP3, and members of the ErbB family - the backbones of the helices are in contact, and they invariably display networks of 4 to 8 weak hydrogen bonds between Cα-H carbon donors and carbonyl acceptors on opposing helices (Cα-H∙∙∙O=C hydrogen bonds)...
October 13, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29027716/cytotoxicity-of-group-5-transition-metal-ditellurides-mte2-m-v-nb-ta
#14
Martin Pumera
Much research effort has been put in to study layered compounds with transition metal dichalcogenides (TMDs) being one of the most studied compounds. Due to their extraordinary properties such as excellent electrochemical properties, tuneable band gaps and low shear resistance due to weak van der Waals interactions between layers, TMDs have been found to have a wide application such as electrocatalyst for hydrogen evolution reactions, supercapacitors, biosensors, field-effect transistors (FETs), photovoltaic and lubricant additives...
October 13, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29026258/comparison-of-high-pressure-behavior-of-physicochemical-properties-of-the-di-and-triacylglycerols-established-by-ultrasonic-methods
#15
A Balcerzak
Two samples of triacylglycerols i.e., olive oil and triolein, and one sample of diacylglycerol were investigated. In the course of compression, the density of the samples was determined by measurements of the change of piston position in a pressure chamber and volume correction due to chamber expansion under pressure. The speed of sound was evaluated from the time of flight of an ultrasonic impulse between emitting and receiving transducers placed in the high pressure chamber. The adiabatic compressibility, the intermolecular free length, the molar volume, the van der Waals' constant b and the surface tension were evaluated from the density, the speed of sound and the average molecular mass...
2017: Journal of the American Oil Chemists' Society
https://www.readbyqxmd.com/read/29024087/chemical-intercalation-of-topological-insulator-grid-nanostructures-for-high-performance-transparent-electrodes
#16
Yunfan Guo, Jinyuan Zhou, Yujing Liu, Xu Zhou, Fengrui Yao, Congwei Tan, Jinxiong Wu, Li Lin, Kaihui Liu, Zhongfan Liu, Hailin Peng
2D layered nanomaterials with strong covalent bonding within layers and weak van der Waals' interactions between layers have attracted tremendous interest in recent years. Layered Bi2 Se3 is a representative topological insulator material in this family, which holds promise for exploration of the fundamental physics and practical applications such as transparent electrode. Here, a simultaneous enhancement of optical transmittancy and electrical conductivity in Bi2 Se3 grid electrodes by copper-atom intercalation is presented...
October 10, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29022020/weak-c-hf-c-hydrogen-bonds-make-a-big-difference-in-graphane-fluorographane-and-fluorographene-fluorographane-bilayers
#17
Minglei Sun, Jyh-Pin Chou, Yiming Zhao, Jin Yu, Wencheng Tang
Using density functional theory computations with van der Waals (vdW) corrections, we reveal that C-HF-C hydrogen bonding exists in graphane/fluorographene and fluorographane/fluorographane bilayers. The significant C-HF-C hydrogen bonding is strong enough to combine two separate monolayers to form the bilayer. Interestingly, both the graphane/fluorographene and fluorographane/fluorographane bilayers are metallic in the most stable stacking configuration. Applying a perpendicular electric field can effectively open a bandgap for both bilayers, and we found that the field-induced gap opening for both graphane/fluorographene and fluorographane/fluorographane bilayers can be enhanced by biaxial tensile strain...
October 12, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29020769/cofacially-arrayed-polyfluorenes-spontaneous-formation-of-%C3%AF-stacked-assemblies-in-the-gas-phase
#18
Maxim V Ivanov, Neil James Reilly, Brandon Uhler, Damian Kokkin, Rajendra Rathore, Scott Allen Reid
Understanding geometrical and size dependencies of through-space charge delocalization in multichromophoric systems is critical to model electron transfer and transport in materials and biomolecules. In this work, we examine the size evolution of hole delocalization in van der Waals clusters of fluorene (i.e., (F)n), where a range of geometries are possible, reflecting both -stacking and C-H/ interactions. Using mass-selected two-color resonant two-photon ionization spectroscopy (2CR2PI), we measure electronic spectra and vertical ionization potentials (IPs) in the gas-phase...
October 11, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29019911/the-effects-of-alkyl-chain-combinations-on-the-structural-and-mechanical-properties-of-biomimetic-ion-pair-amphiphile-bilayers
#19
Cheng-Hao Chen, Ching-An Tian, Chi-Cheng Chiu
Ion pair amphiphile (IPA), a lipid-like complex composed of a pair of cationic and anionic surfactants, has great potentials in various pharmaceutical applications. In this work, we utilized molecular dynamics (MD) simulation to systematically examine the structural and mechanical properties of the biomimetic bilayers consist of alkyltrimethyl-ammonium-alkylsulfate (CmTMA⁺-CnS(-)) IPAs with various alkyl chain combinations. Our simulations show an intrinsic one-atom offset for the CmTMA⁺ and CnS(-) alignment, leading to the asymmetric index definition of ΔC = m - (n + 1)...
October 11, 2017: Bioengineering
https://www.readbyqxmd.com/read/29019462/stability-and-electronic-properties-of-hybrid-sno-bilayers-sno-graphene-and-sno-bn
#20
Qing Guo, Gaoxue Wang, Ashok Kumar, Ravi Pandey
Van der Waals structures based on two dimensional materials have been considered as promising materials for novel nanoscale electronic devices. Two dimensional SnO films which display intrinsic p-type semiconducting properties were fabricated recently. In this paper, we consider the vertically stacked heterostructures consisting of SnO monolayer with graphene or BN monolayer to investigate their stability, electronic and transport properties using density functional theory. The calculated results find that properties of the constituent monolayers are retained in these SnO-based heterostructures, and a p-type Schottky barrier is formed in the SnO/graphene heterostructure...
October 11, 2017: Nanotechnology
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