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Huilin Wang, Liubin Feng, Geoffrey I Webb, Lukasz Kurgan, Jiangning Song, Donghai Lin
No abstract text is available yet for this article.
June 22, 2017: Briefings in Bioinformatics
Nicholas Ade
This study evaluates the role of defects on the performances of synthetic diamond sensors on exposure to mammography X-rays. Through systematic investigations, the main cause of instability of response of examined sensors necessitating pre-irradiation was isolated and ascribed to the presence of ambient light which has the effect of emptying shallow trapping levels. The changes in response between measurements in light and dark conditions varied from 2.8 ± 1.2% to 63.0 ± 0.3%. Sensitivities between 0.4 and 6...
June 17, 2017: Applied Radiation and Isotopes
Jess Estrada, Vincent Lavallo
Discovered by Hawthorne in 1965, dicarbollide ions are an intriguing class of nido-carboranes that mimic the behavior of the cyclopentadienyl anion. Here we show that it is possible to directly link the dicarbollide ion to an N-Heterocyclic Carbene (NHC), to form an isolable N-dicarbollide NHC dianion. This molecule can be accessed via the sequential double deprotonation of a mono-nido-carboranyl imidazolium zwitterion. As revealed by a single crystal x-ray diffraction study, the first deprotonation leads to a monoanionic dicarbollide ion that adopts a bis(dicarbollide) structure in the solid-state...
June 26, 2017: Angewandte Chemie
Wei Hao, Justyna Aleksandra Wojdyla, Rong Zhao, Ruiyun Han, Rajat Das, Ivan Zlatev, Muthiah Manoharan, Meitian Wang, Sheng Cui
Middle East respiratory syndrome coronavirus (MERS-CoV) remains a threat to public health worldwide; however, effective vaccine or drug against CoVs remains unavailable. CoV helicase is one of the three evolutionary most conserved proteins in nidoviruses, thus making it an important target for drug development. We report here the first structure of full-length coronavirus helicase, MERS-CoV nsp13. MERS-CoV helicase has multiple domains, including an N-terminal Cys/His rich domain (CH) with three zinc atoms, a beta-barrel domain and a C-terminal SF1 helicase core with two RecA-like subdomains...
June 26, 2017: PLoS Pathogens
Roger P Dotsey, Elizabeth A S Moser, George J Eckert, Richard L Gregory
OBJECTIVE: To examine the effects of cola-flavored beverages and caffeine on growth and metabolism of Streptococcus mutans biofilm. This study was designed to determine if carbonated beverages or caffeine can increase S. mutans growth and biofilm formation and metabolic activity in vitro, potentially leading to increased S. mutans-associated cariogenicity in children that consume them. STUDY DESIGN: Six different cola-flavored products, plus pure caffeine, and pure high fructose corn syrup (HFCS), at different concentrations similar to those in the beverages were tested...
2017: Journal of Clinical Pediatric Dentistry
Yong Du, Jingyao Gao, Tingting Chen, Chao Zhang, Jian Ji, Zhi-Kang Xu
Poly(oligoethylene glycol methacrylate) (POEGMA) and zwitterionic polymer brushes have been widely used for constructing biocompatible or antifouling surfaces, and their oxidative stability is very important to the practical application. Herein, POEGMA, poly(sulfobetaine methacrylate) (PSBMA), poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC), and poly(carboxybetaine methacrylate) (PCBMA) were grafted on quartz crystal microbalance (QCM) chips via surface initiated atom transfer radical polymerization (SI-ATRP)...
June 26, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Shiva Moaven, Jingze Yu, Jason Yasin, Daniel K Unruh, Anthony F Cozzolino
Antimony(III) alkoxide cages were designed as building blocks for predictable supramolecular self-assembly. Supramolecular synthons featuring two Sb···O secondary bonding interactions (SBIs), each SBI stronger than 30 kJ/mol, were used to drive the formation of the supramolecular architectures. Judicious choice of pendant groups provided predictable control over the formation of self-assembled 3D columnar helices, which crystallized with hollow morphologies, or a self-assembled 2D bilayer. The Sb-O stretching frequency provides a spectroscopic signature of Sb···O SBI formation...
June 26, 2017: Inorganic Chemistry
Subhajit Bhunia, Sabuj Kanti Das, Rajkumar Jana, Sebastian C Peter, Santanu Bhattacharya, Matthew Addicoat, Asim Bhaumik, Anirban Pradhan
A [2+2] Schiff base type condensation between 5, 10, 15, 20-tetrakis(4-aminophenyl)porphyrin (TAP) and 1,3,6,8-tetrakis (4-formylphenyl) pyrene (TFFPy) under solvothermal condition yields a crystalline, quasi-two dimensional covalent organic framework (SB-PORPy-COF). The porphyrin and pyrene units are alternatively occupied in the vertex of 3D triclinic crystal having permanent micro-porosity with moderately high surface area (~869 m2g-1) and promising chemical stability. The AA stacking of the monolayers give a pyrene bridged conducting channel...
June 26, 2017: ACS Applied Materials & Interfaces
Dan Zhao, Fa-Xue Ma, Yun-Chang Fan, Lei Zhang, Rui-Juan Zhang, Pei-Gao Duan
Two new lead rare-earth polyborates, PbTbB7O13 and PbEuB7O13, have been successfully synthesized via a high temperature molten salt method. Single crystal X-ray diffraction analysis reveals that they are isostructural and feature a 2D layer structure that contains alternating layers of [B7O13]∞ and [Tb]∞. The [B7O13]∞ layer is constructed of BO3 and BO4 groups with the fundamental building block of B7O17 (3Δ4□: <Δ2□>Δ<Δ2□>). Solid solutions of PbTb1-xEuxB7O13 (x = 0-1) were prepared via a solid state reaction and the photoluminescence properties were studied...
June 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Olga V Yakubovich, Larisa V Shvanskaya, Olga V Dimitrova, Olga S Volkova, Alexander N Vasiliev
The manganese end member of triplite-triploidite series of compounds, Mn2(PO4)OH, is synthesized by a hydrothermal method. Its crystal structure is refined in the space group P21/c with a = 12.411(1) Å, b = 13.323(1) Å, c = 10.014(1) Å, β = 108.16(1), V = 1573.3 Å(3), Z = 8, and R = 0.0375. Evidenced in measurements of magnetization M and specific heat Cp, Mn2(PO4)OH reaches a long range antiferromagnetic order at TN = 4.6 K. As opposed to both triplite Mn2(PO4)F and triploidite-type Co2(PO4)F, the title compound is magnetically frustrated being characterized by the ratio of Curie-Weiss temperature Θ to Néel temperature TN of about 20...
June 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Hui Wu, Yuji Higaki, Shiki Nojima, Atsushi Takahara
The orientation and crystallization of regioregular poly(3-dodecylthiophene) (P3DDT) in different diameter nanopores were investigated. P3DDT nanowires were prepared by a melt-wetting nonporous alumina template with P3DDT melts. The microstructure of the nanowires was analyzed by micro-Fourier transform infrared spectroscopy, grazing incidence wide angle X-ray diffraction, and differential scanning calorimetry. Although Form I modification prevails in all the nanowires, Form I crystals decrease and Form II crystals increase as the pore diameter decreases...
June 26, 2017: Soft Matter
Van Son Nguyen, Laureen Logger, Silvia Spinelli, Pierre Legrand, Thi Thanh Huyen Pham, Thi Trang Nhung Trinh, Yassine Cherrak, Abdelrahim Zoued, Aline Desmyter, Eric Durand, Alain Roussel, Christine Kellenberger, Eric Cascales, Christian Cambillau
The type VI secretion system (T6SS) is a multiprotein machine widespread in Gram-negative bacteria that delivers toxins into both eukaryotic and prokaryotic cells. The mechanism of action of the T6SS is comparable to that of contractile myophages. The T6SS builds a tail-like structure made of an inner tube wrapped by a sheath, assembled under an extended conformation. Contraction of the sheath propels the inner tube towards the target cell. The T6SS tail is assembled on a platform-the baseplate-which is functionally similar to bacteriophage baseplates...
June 26, 2017: Nature Microbiology
Xiao-Xiao Zhang, Ting Cao, Zhengguang Lu, Yu-Chuan Lin, Fan Zhang, Ying Wang, Zhiqiang Li, James C Hone, Joshua A Robinson, Dmitry Smirnov, Steven G Louie, Tony F Heinz
Monolayer transition metal dichalcogenide crystals, as direct-gap materials with strong light-matter interactions, have attracted much recent attention. Because of their spin-polarized valence bands and a predicted spin splitting at the conduction band edges, the lowest-lying excitons in WX2 (X = S, Se) are expected to be spin-forbidden and optically dark. To date, however, there has been no direct experimental probe of these dark excitons. Here, we show how an in-plane magnetic field can brighten the dark excitons in monolayer WSe2 and permit their properties to be observed experimentally...
June 26, 2017: Nature Nanotechnology
You Zhou, Giovanni Scuri, Dominik S Wild, Alexander A High, Alan Dibos, Luis A Jauregui, Chi Shu, Kristiaan De Greve, Kateryna Pistunova, Andrew Y Joe, Takashi Taniguchi, Kenji Watanabe, Philip Kim, Mikhail D Lukin, Hongkun Park
Transition metal dichalcogenide (TMD) monolayers with a direct bandgap feature tightly bound excitons, strong spin-orbit coupling and spin-valley degrees of freedom. Depending on the spin configuration of the electron-hole pairs, intra-valley excitons of TMD monolayers can be either optically bright or dark. Dark excitons involve nominally spin-forbidden optical transitions with a zero in-plane transition dipole moment, making their detection with conventional far-field optical techniques challenging. Here, we introduce a method for probing the optical properties of two-dimensional materials via near-field coupling to surface plasmon polaritons (SPPs)...
June 26, 2017: Nature Nanotechnology
Kazuki Miyata, John Tracey, Keisuke Miyazawa, Ville Anton Haapasilta, Peter Spijker, Yuta Kawagoe, Adam S Foster, Katsuo Tsukamoto, Takeshi Fukuma
The microscopic understanding of the crystal growth and dissolution processes have been greatly advanced by the direct imaging of nanoscale step flows by atomic force microscopy (AFM), optical interferometry and x-ray microscopy. However, one of the most fundamental events that govern their kinetics, namely, atomistic events at the step edges have not been well understood. In this study, we have developed high-speed frequency modulation AFM (FM-AFM) and enabled true atomic-resolution imaging in liquid at ~1 s/frame, which is ~50 times faster than the conventional FM-AFM...
June 26, 2017: Nano Letters
Yun Huang, Akisato Takata, Yoshinobu Tsujii, Kohji Ohno
We here introduce a technique for the direct formation of semisoft colloidal crystals of hybrid particles in non-volatile ionic liquid solvents. The hybrid particles are comprised of a silica core and a densely grafted polymer brush shell, which were synthesized by surface-initiated living radical polymerization. A phase transition of the suspensions from a disordered fluid to a crystallized system was observed within a narrow concentration range. Confocal laser scanning microscopy observation and UV-VIS spectrometry confirmed the highly ordered structure of the hybrid particles in ionic liquids...
June 26, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Zhenhua Cong, Bowen Lin, Weiqing Li, Jian Niu, Feng Yan
Liquid crystals formed by the self-assembly of small molecules are very promising smart materials because of their unique properties, such as self-assembled multivalency, biocompatibility, and fast response to external stimuli. Here we report an iridescent liquid crystal system composed of water layers sandwiched by two bilayer membranes that consist of a self-assembled nonionic surfactant hexadecylglyceryl maleate (HGM) and a tiny amount of ionic surfactants. It is found the iridescent color of the liquid crystal system changes greatly with a trace of change of the ionic surfactants' concentration...
June 26, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Huabin Kong, Chade Lv, Chunshuang Yan, Gang Chen
To achieve high-efficiency lithium ion batteries (LIBs), an effective active electrode material is vital. For the first time, mesoporous single crystals cobalt-doped Fe2O3 (MSCs Co-Fe2O3) is synthesized using formamide as a pore forming agent, through a solvothermal process followed by calcination. Compared with mesoporous single crystals Fe2O3 (MSCs Fe2O3) and cobalt-doped Fe2O3 (Co-Fe2O3), MSCs Co-Fe2O3 exhibits a significantly improved electrochemical performance with high reversible capacity, excellent rate capability, and cycling life as anode materials for LIBs...
June 26, 2017: Inorganic Chemistry
Aaron J Wolfe, Yi-Ching Hsueh, Adam R Blanden, Mohammad M Mohammad, Bach Pham, Avinash Kumar Thakur, Stewart N Loh, Min Chen, Liviu Movileanu
Understanding how membrane proteins interact with detergents is of fundamental and practical significance in structural and chemical biology as well as in nanobiotechnology. Current methods for inspecting protein-detergent complex (PDC) interfaces require high concentrations of protein and are of low throughput. Here, we describe a scalable, spectroscopic approach that uses nanomolar protein concentrations in native solutions. This approach, which is based on steady-state fluorescence polarization (FP) spectroscopy, kinetically resolves the dissociation of detergents from membrane proteins and protein unfolding...
June 26, 2017: Analytical Chemistry
Alexander Kasznel, Yitao Zhang, Yang Hai, David M Chenoweth
Previously, we have demonstrated that replacement of the strictly conserved glycine in collagen with aza-glycine provides a general solution for stabilizing triple helical collagen peptides.1-2 The additional hydrogen bond and conformational constraints provided by aza-glycine increases the thermal stability and rate of folding in collagen peptides composed of Pro-Hyp-Gly triplet repeats, allowing for truncation to the smallest self-assembling peptide systems observed to date. Here we show that aza-glycine substitution enhances the stability of an arginine-containing collagen peptide and provide a structural basis for this stabilization with an atomic resolution crystal structure...
June 26, 2017: Journal of the American Chemical Society
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