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Stefano Mangani, Cecilia Pozzi, Flavio Di Pisa, Filomena De Luca, Manuela Benvenuti, Jean-Denis Docquier
β-lactamases (BLs) are important antibiotic resistance determinants that significantly compromise the efficacy of valuable β-lactam antibacterial drugs. For that reason, combinations with β-lactamase inhibitor were developed. Avibactam is the first non-β-lactam BL inhibitor introduced in clinical practice. Ceftazidime-avibactam represents one of the few last-resort antibiotics available for the treatment of infections caused by near pandrug-resistant bacteria. TRU-1 is a chromosomally-encoded AmpC-type BL of Aeromonas enteropelogenes, related to the FOX-type BLs and constitutes a good model for class C BLs...
May 22, 2018: ChemMedChem
Haoxuan Sun, Kaimo Deng, Yayun Zhu, Min Liao, Jie Xiong, Yanrong Li, Liang Li
Lead halide perovskite solar cells (PSCs) with the high power conversion efficiency (PCE) typically use mesoporous metal oxide nanoparticles as the scaffold and electron-transport layers. However, the traditional mesoporous layer suffers from low electron conductivity and severe carrier recombination. Here, antimony-doped tin oxide nanorod arrays are proposed as novel transparent conductive mesoporous layers in PSCs. Such a mesoporous layer improves the electron transport as well as light utilization. To resolve the common problem of uneven growth of perovskite on rough surface, the dynamic two-step spin coating strategy is proposed to prepare highly smooth, dense, and crystallized perovskite films with micrometer-scale grains, largely reducing the carrier recombination ratio...
May 22, 2018: Advanced Materials
Seline Glorieux, Liselot Steen, Jos De Brabanter, Imogen Foubert, Ilse Fraeye
The aim of this research was to simultaneously study the effect of meat type (chicken breast and leg meat), animal fatty acid composition (selected pork backfats having a low and high degree of saturation, respectively), and isothermal temperature (50, 60, 70, and 80 °C) on the viscoelastic properties of meat batters during and after application of different time-temperature profiles. Gelation of meat proteins contributed most to the viscoelastic properties of meat batters during heating, whereas crystallization of the lipids especially contributed to the viscoelastic properties during the cooling phase...
May 22, 2018: Journal of Food Science
Luis A Serrano, Maximiliano J Fornerod, Ye Yang, Simon Gaisford, Francesco Stellacci, Stefan Guldin
Herein, we report on the phase behaviour of a binary liquid mixture composed of methanol (MeOH) and the thermotropic liquid crystal 4-cyano-4'-pentylbiphenyl (5CB). The corresponding phase diagram combines features of a conventional liquid-liquid mixture with characteristics that are particular to the nematic liquid crystal. We observe four arrangements as a function of composition and temperature, namely monophasic isotropic, monophasic nematic, biphasic isotropic-isotropic and biphasic isotropic-nematic, with an upper critical solution temperature of 24...
May 22, 2018: Soft Matter
Dominik Naglav, Briac Tobey, Kevin Dzialkowski, Dieter Bläser, Christoph Wölper, Georg Jansen, Stephan Schulz
Spontaneous ion separation of the scorpionate beryllium complex, TpBeI 1 (Tp = 1-trispyrazolylborate), occurs upon treatment with THF, yielding [TpBe(thf)]I 2, which was characterized by heteronuclear NMR spectroscopy (1H, 9Be, 13C) and structurally characterized by single crystal X-ray diffraction. 2 represents a rare example of a structurally characterized monocationic beryllium complex, and to the best of our knowledge, the synthesis of 2 by a solvent-induced ion separation has previously only been observed in the reactions of beryllium dihalides with strong Lewis bases...
May 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Alexandra Hicken, Andrew J P White, Mark R Crimmin
The preparation and structural characterisation of three new heterobimetallic hydride complexes containing 3-centre,2-electron W-H-Cu bonds is reported. These complexes have been characterised by single crystal X-ray crystallography and multinuclear NMR spectroscopy. The bonding in these complexes has been analysed by DFT calculations.
May 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Xiao Wan, Yuan Yao, Lei Fang, Junjun Liu
Butyrylcholinesterase (BChE) has been actively involved in drug discoveries from many fields for decades. In the crystal structure of the BChE-tacrine complex, there is an unanticipated formyl-proline molecule resolved very close to tacrine, raising an essential question on how reliable it is to apply the binding pose in a crystal structure to analyze related experimental observations, in which no formyl-proline is actually involved. In this study, by performing a series of 100 ns molecular dynamics simulations, we demonstrate that it is safe to employ the structural information from this crystal structure to analyze related experimental observations...
May 22, 2018: Physical Chemistry Chemical Physics: PCCP
Chang Woo Lee, Sun-Ha Park, Sung Gu Lee, Hyun Ho Park, Hak Jun Kim, HaJeung Park, Hyun Park, Jun Hyuck Lee
Dihydrodipicolinate reductase (DHDPR) is a key enzyme in the diaminopimelate- and lysine-synthesis pathways that reduces DHDP to tetrahydrodipicolinate. Although DHDPR uses both NADPH and NADH as a cofactor, the structural basis for cofactor specificity and preference remains unclear. Here, we report that Paenisporosarcina sp. TG-14 PaDHDPR has a strong preference for NADPH over NADH, as determined by isothermal titration calorimetry and enzymatic activity assays. We determined the crystal structures of PaDHDPR alone, with its competitive inhibitor (dipicolinate), and the ternary complex of the enzyme with dipicolinate and NADPH, with results showing that only the ternary complex had a fully closed conformation and suggesting that binding of both substrate and nucleotide cofactor is required for enzymatic activity...
May 21, 2018: Scientific Reports
Christoph Rameshan, Hao Li, Kresimir Anic, Matteo Roiaz, Verena Pramhaas, Raffael Rameshan, Raoul Blume, Michael Hävecker, Jan Knudsen, Axel Knop-Gericke, Gunther Rupprechter
Due to the need of sustainable energy sources, methane dry reforming (MDR) is a useful reaction for the conversion of the greenhouse gases CH<sub>4</sub> and CO<sub>2</sub> to synthesis gas (CO + H<sub>2</sub>). Syngas is the basis for a wide range of commodity chemicals and can be utilized for fuel production via Fischer-Tropsch (FT) synthesis. The current study focuses on spectroscopic investigations of the surface and reaction properties of a ZrO<sub>2</sub>/Pt inverse model catalyst, i...
May 22, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Vivek Kumar, Manfred Reehuis, Andreas Hoser, Peter Adler, Claudia Felser
We have investigated the crystal and magnetic structure of Mn<sub>2</sub>PtPd alloy using powder X-ray and neutron diffraction experiments. This compound is believed to belong to the Heusler family having crystal symmetry I4/mmm (TiAl<sub>3</sub>-type). However, in this work we found that the Pd and Pt atoms are disordered and thus Mn<sub>2</sub>PtPd crystallizes in the L1<sub>0</sub> structure having P4/mmm symmetry (CuAu-I type) like MnPt and MnPd binary alloys...
May 22, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Huifang Ma, Peng Chen, Bo Li, Jia Li, Ruoqi Ai, Zhengwei Zhang, Guangzhuang Sun, Kangkang Yao, Zhaoyang Lin, Bei Zhao, Ruixia Wu, Xuwan Tang, Xidong Duan, Xiangfeng Duan
The recent discovery of topological semimetals has stimulated extensive research interest due to their unique electronic properties and novel transport properties related to a chiral anomaly. However, the studies to date are largely limited to bulk crystals and exfoliated flakes. Here, we report the controllable synthesis of ultrathin two-dimensional (2D) platinum telluride (PtTe2 ) nanosheets with tunable thickness and investigate the thickness-dependent electronic properties. We show that PtTe2 nanosheets can be readily grown, using a chemical vapor deposition approach, with a hexagonal or triangular geometry and a lateral dimension of up to 80 μm, and the thickness of the nanosheets can be systematically tailored from over 20 to 1...
May 22, 2018: Nano Letters
Yatao Zhang, Yijia Shen, Jingwei Hou, Yiming Zhang, Winny Fam, Jindun Liu, Thomas D Bennett, Vicki Chen
Block copolymer materials have been considered as promising candidates to fabricate gas separation membranes. This microphase separation affects the polymer chain packing density and molecular separation efficiency. Here we demonstrate a method to template microphase separation within a thin composite Pebax membrane, through the controllable self-assembly of one-dimensional halloysite nanotubes (HNTs) within the thin film via solution casting technique. Crystallisation of the polyamide component is induced at the HNT surface, guiding subsequent crystal growth around the tubular structure...
May 22, 2018: ACS Applied Materials & Interfaces
A James O'Malley, Sandra L Wong
No abstract text is available yet for this article.
May 21, 2018: Annals of Surgical Oncology
Xiao-Qin Wei, Qian Pi, Fu-Xing Shen, Dong Shao, Hai-Yan Wei, Xin-Yi Wang
By reaction of K4[MoIII(CN)7]·2H2O, Mn(ClO4)2·6H2O and bidentate chelating ligands, three new cyano-bridged compounds, namely Mn2(3-pypz)(H2O)(CH3CN)[Mo(CN)7] (1), Mn2(1-pypz)(H2O)(CH3CN)[Mo(CN)7] (2) and Mn2(pyim)(H2O)(CH3CN)[Mo(CN)7] (3) (3-pypz = 2-(1H-pyrazol-3-yl)pyridine, 1-pypz = 2-(1H-pyrazol-1-yl)pyridine, pyim = 2-(1H-imidazol-2-yl)pyridine), have been synthesized and characterized structurally and magnetically. Single crystal X-ray analyses revealed that although the chelating ligands are different, compounds 1 to 3 are isomorphous and crystallize in the same monoclinic space group C2/m...
May 22, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Shaodong Hu, Annie Gagnoud, Yves Fautrelle, Rene Moreau, Xi Li
Aluminum alloy in situ functionally graded materials (FGMs) have been successfully fabricated using directional solidification under an axial static magnetic field. Al-Zn, Al-Ni and Al-Cu alloys with a hypereutectic composition were selected to produce FGMs. Experimental results show that the graded composition of the primary phases (i.e., Zn, Al3 Ni and Al2 Cu) is obvious along the longitudinal section of the sample. The graded composition of the primary phases could be controlled by the value of the magnetic field, growth rate and temperature gradient...
May 21, 2018: Scientific Reports
Min-Zhuo Cheng, Jing Zhang, Dequan Bao, Xiwei Huang
In this communication, we assembled ordered polystyrene (PS) microsphere array as a template with the drop-coating method, and the oxygen plasma was used to etch the template to adjust the spacing between the PS microspheres. Nano-triangular gold array and silver Nano-pyramid array were obtained by ion beam sputtering to deposit precious metal gold and silver. We observed the surface morphology of Au and Au/Ag composite films by scanning electron microscope and characterized the films by X-ray diffraction and Ultraviolet/visible light spectrophotometer...
May 21, 2018: Electrophoresis
Maziar Heidari, Robinson Cortes-Huerto, Kurt Kremer, Raffaello Potestio
To understand the properties of a complex system it is often illuminating to perform a comparison with a simpler, even idealised one. A prototypical application of this approach is the calculation of free energies and chemical potentials in liquids, which can be decomposed in the sum of ideal and excess contributions. In the same spirit, in computer simulations it is possible to extract useful information on a given system making use of setups where two models, an accurate one and a simpler one, are concurrently employed and directly coupled...
May 23, 2018: European Physical Journal. E, Soft Matter
Zhirui Niu, Shaokang Zhang, Lin Zhu
Mn-Zn ferrite (Mn1 - x Zn x Fe2 O4 , x = 0.2, 0.4, 0.6, and 0.8) nanomaterials were prepared by bioleaching and hydrothermal synthesis from waste Zn-Mn batteries. The materials were characterized by XRD, SEM, BET, VSM, CEC, and isoelectric point. It turned out when x = 0.4, synthesized Mn-Zn ferrite had best performance which was nanoferrite crystal structure with a specific surface area that reached 37.77 m2 /g, the saturation magnetization was 62.85 emu/g, and isoelectric point and the CEC value were 7...
May 21, 2018: Environmental Science and Pollution Research International
Aiguo Zhao, Feng Han
In higher plants, the tetrapyrrole biosynthesis pathway starts from the reaction catalyzed by the rate-limiting enzyme, glutamyl-tRNAGlu reductase (GTR). In Arabidopsis thaliana, GTR is controlled by post-transcriptional regulators such as GTR binding protein (GBP), which stimulates AtGTR activity. The NADPH-binding domain of AtGTR undergoes a substantial movement upon GBP binding. Here, we report the crystal structure of AtGTR-NADPH-GBP ternary complex. NADPH binding causes slight structural changes compared with the AtGTR-GBP binary complex, and possibly take a part of the space needed by the substrate glutamyl-tRNAGlu ...
May 21, 2018: Photosynthesis Research
Jin Woo Choi, Hee Chul Woo, Xiaoguang Huang, Wan-Gil Jung, Bong-Joong Kim, Sie-Wook Jeon, Sang-Youp Yim, Jae-Suk Lee, Chang-Lyoul Lee
The photoluminescence quantum yield (PLQY) and charge carrier mobility of organic-inorganic perovskite QDs were enhanced by the optimization of crystallinity and surface passivation as well as solid-state ligand exchange. The crystallinity of perovskite QDs was determined by the Effective solvent field (Esol) of various solvents for precipitation. The solvent with high Esol could more quickly countervail the localized field generated by the polar solvent, and it causes fast crystallization of the dissolved precursor, which results in poor crystallinity...
May 22, 2018: Nanoscale
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