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https://www.readbyqxmd.com/read/28532123/origin-of-dislocation-luminescence-centers-and-their-reorganization-in-p-type-silicon-crystal-subjected-to-plastic-deformation-and-high-temperature-annealing
#1
Bohdan Pavlyk, Markiyan Kushlyk, Dmytro Slobodzyan
Changes of the defect structure of silicon p-type crystal surface layer under the influence of plastic deformation and high temperature annealing in oxygen atmosphere were investigated by deep-level capacitance-modulation spectroscopy (DLCMS) and IR spectroscopy of molecules and atom vibrational levels. Special role of dislocations in the surface layer of silicon during the formation of its energy spectrum and rebuilding the defective structure was established. It is shown that the concentration of linear defects (N ≥ 10(4) cm(-2)) enriches surface layer with electrically active complexes (dislocation-oxygen, dislocation-vacancy, and dislocation-interstitial atoms of silicon) which are an effective radiative recombination centers...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28532113/nanofibers-of-human-tropoelastin-inspired-peptides-structural-characterization-and-biological-properties
#2
Valeria Secchi, Stefano Franchi, Marco Fioramonti, Giovanni Polzonetti, Giovanna Iucci, Brigida Bochicchio, Chiara Battocchio
Regenerative medicine is taking great advantage from the use of biomaterials in the treatments of a wide range of diseases and injuries. Among other biomaterials, self-assembling peptides are appealing systems due to their ability to spontaneously form nanostructured hydrogels that can be directly injected into lesions. Indeed, self-assembling peptide scaffolds are expected to behave as biomimetic matrices able to surround cells, to promote specific interactions, and to control and modify cell behavior by mimicking the native environment as well...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532073/fabrication-of-vinyl-organosilicon-poly-n-n-4-5-dihydroxy-1-2-phenylene-bis-methylene-bisacrylamide-core-shell-antibacterial-agent
#3
Zhijia Zhang, Xiaole Zhao, Yingchun Su, Defeng Xing, Xiaojun Han
We demonstrate that antibacterial agent N, N'-[(4, 5-dihydroxy-1, 2-phenylene)bis(methylene)]bisacrylamide (OHABA) can be assembled on the surface of vinyl organosilicon nanospheres (VOSNs) by atom transfer radical polymerization (ATRP). Chemically cross-linked vinyl organosilicon cores were facilely fabricated by sol-gel method as support, which densely grafted poly-OHABA (POHABA) as shells. Antibacterial assessment test results revealed that POHABA-based core@shell structure displayed high antibacterial performance, long-term stability, and kept broad-spectrum antibacterial effect of against Gram-negative and Gram-positive bacteria...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532052/poly-%C3%AE%C2%B5-caprolactone-modification-via-surface-initiated-atom-transfer-radical-polymerization-with-bio-inspired-phosphorylcholine
#4
Liu He, Lei Huang, Songbai Zhang, Yuanwei Chen, Xianglin Luo
Bio-inspired phosphorylcholine modification on material surface has shown great promise in constructing biocompatible materials. In this study, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) was grown on poly(ε-caprolactone) (PCL) surface in order to suppress protein adsorption and cells adhesion and to improve blood compatibility. The initiator for surface initiated atom transfer radical polymerization (SI-ATRP) was covalently tethered on PCL surface and then PMPC brushes with diverse graft amounts were grafted to PCL film...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532025/new-tetrahedral-zinc-halide-schiff-base-complexes-synthesis-crystal-structure-theoretical-3d-hirshfeld-surface-analyses-antimicrobial-and-thermal-studies
#5
L Taghizadeh, M Montazerozohori, A Masoudiasl, S Joohari, J M White
A new bidentate Schiff base ligand named as N,N'-bis((E)-3-phenylallylidene)butane-1,4-diamine (L) and three its zinc halide complexes were synthesized and characterized by FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectroscopy. The crystal structure of zinc bromide and iodide complexes were characterized using single crystal X-ray diffraction. The two structures are isomorphous, crystallizing in the monoclinic crystal system with space group C2/c with closely similar unit cell dimensions. In these complexes, the Zn(II) ion is in the center of a distorted tetrahedral environment completed by two iminic nitrogen atoms of Schiff base ligand and two halide anions...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28531275/molecular-envelope-and-atomic-model-of-an-anti-terminated-glyqs-t-box-regulator-in-complex-with-trnagly
#6
Bhaskar Chetnani, Alfonso Mondragón
A T-box regulator or riboswitch actively monitors the levels of charged/uncharged tRNA and participates in amino acid homeostasis by regulating genes involved in their utilization or biosynthesis. It has an aptamer domain for cognate tRNA recognition and an expression platform to sense the charge state and modulate gene expression. These two conserved domains are connected by a variable linker that harbors additional secondary structural elements, such as Stem III. The structural basis for specific tRNA binding is known, but the structural basis for charge sensing and the role of other elements remains elusive...
May 22, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28530750/first-principles-study-of-the-structural-stability-and-electrochemical-properties-of-na2msio4-m-mn-fe-co-and-ni-polymorphs
#7
F Bianchini, H Fjellvåg, P Vajeeston
Sodium orthosilicates Na2MSiO4 (M = Mn, Fe, Co and Ni) have attracted much attention due to the possibility of exchanging two electrons per formula unit. They are also found to exhibit great structural stability due to a diamond-like arrangement of tetrahedral groups. In this work, we have systematically studied the possible polymorphism of these compounds by means of density functional theory, optimising the structure of a number of systems with different group symmetries. The ground state is found to be Pc-symmetric for all the considered M = Mn, Fe, Co, Ni, and several similar structures exhibiting different symmetries coexist within a 0...
May 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28530728/ultrafast-coulomb-explosion-of-a-diiodomethane-molecule-induced-by-an-x-ray-free-electron-laser-pulse
#8
Tsukasa Takanashi, Kosuke Nakamura, Edwin Kukk, Koji Motomura, Hironobu Fukuzawa, Kiyonobu Nagaya, Shin-Ichi Wada, Yoshiaki Kumagai, Denys Iablonskyi, Yuta Ito, Yuta Sakakibara, Daehyun You, Toshiyuki Nishiyama, Kazuki Asa, Yuhiro Sato, Takayuki Umemoto, Kango Kariyazono, Kohei Ochiai, Manabu Kanno, Kaoru Yamazaki, Kuno Kooser, Christophe Nicolas, Catalin Miron, Theodor Asavei, Liviu Neagu, Markus Schöffler, Gregor Kastirke, Xiao-Jing Liu, Artem Rudenko, Shigeki Owada, Tetsuo Katayama, Tadashi Togashi, Kensuke Tono, Makina Yabashi, Hirohiko Kono, Kiyoshi Ueda
Coulomb explosion of diiodomethane CH2I2 molecules irradiated by ultrashort and intense X-ray pulses from SACLA, the Japanese X-ray free electron laser facility, was investigated by multi-ion coincidence measurements and self-consistent charge density-functional-based tight-binding (SCC-DFTB) simulations. The diiodomethane molecule, containing two heavy-atom X-ray absorbing sites, exhibits a rather different charge generation and nuclear motion dynamics compared to iodomethane CH3I with only a single heavy atom, as studied earlier...
May 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28530710/engineering-protein-stability-with-atomic-precision-in-a-monomeric-miniprotein
#9
Emily G Baker, Christopher Williams, Kieran L Hudson, Gail J Bartlett, Jack W Heal, Kathryn L Porter Goff, Richard B Sessions, Matthew P Crump, Derek N Woolfson
Miniproteins simplify the protein-folding problem, allowing the dissection of forces that stabilize protein structures. Here we describe PPα-Tyr, a designed peptide comprising an α-helix buttressed by a polyproline II helix. PPα-Tyr is water soluble and monomeric, and it unfolds cooperatively with a midpoint unfolding temperature (TM) of 39 °C. NMR structures of PPα-Tyr reveal proline residues docked between tyrosine side chains, as designed. The stability of PPα is sensitive to modifications in the aromatic residues: replacing tyrosine with phenylalanine, i...
May 22, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28530709/recognition-of-egf-like-domains-by-the-notch-modifying-o-fucosyltransferase-pofut1
#10
Zhijie Li, Kristina Han, John E Pak, Malathy Satkunarajah, Dongxia Zhou, James M Rini
Protein O-fucosyltransferase 1 (POFUT1) fucosylates the epidermal growth factor (EGF)-like domains found in cell-surface and secreted glycoproteins including Notch and its ligands. Although Notch fucosylation is critical for development, and POFUT1 deficiency leads to human disease, how this enzyme binds and catalyzes the fucosylation of its diverse EGF-like domain substrates has not been determined. Reported here is the X-ray crystal structure of mouse POFUT1 in complex with several EGF-like domains, including EGF12 and EGF26 of Notch...
May 22, 2017: Nature Chemical Biology
https://www.readbyqxmd.com/read/28530653/structure-of-a-pre-catalytic-spliceosome
#11
Clemens Plaschka, Pei-Chun Lin, Kiyoshi Nagai
Intron removal requires assembly of the spliceosome on pre-mRNA and extensive remodelling to form the spliceosome's catalytic centre. Here we report the cryo-electron microscopy structure of the yeast pre-catalytic B complex spliceosome at near-atomic resolution. The mobile U2 snRNP associates with U4/U6.U5 tri-snRNP through U2/U6 helix II and an interface between U4/U6 di-snRNP and the U2 snRNP SF3b-containing domain, which also transiently contacts the helicase Brr2. The U2 snRNP 3' region is flexibly attached to the SF3b-containing domain and protrudes over the concave surface of tri-snRNP, where the U1 snRNP may reside before its release from the pre-mRNA 5'-splice site...
May 22, 2017: Nature
https://www.readbyqxmd.com/read/28530404/role-of-crystallization-in-the-morphology-of-polymer-non-fullerene-acceptor-bulk-heterojunctions
#12
Kathryn A O'Hara, David P Ostrowski, Unsal Koldemir, Christopher J Takacs, Sean E Shaheen, Alan Sellinger, Michael L Chabinyc
Many high efficiency organic photovoltaics use fullerene-based acceptors despite their high production cost, weak optical absorption in the visible range, and limited synthetic variability of electronic and optical properties. To circumvent this deficiency, non-fullerene small-molecule acceptors have been developed that have good synthetic flexibility, allowing for precise tuning of optoelectronic properties, leading to enhanced absorption of the solar spectrum and increased open-circuit voltages (VOC). We examined the detailed morphology of bulk heterojunctions of poly(3-hexylthiophene) and the small-molecule acceptor HPI-BT to reveal structural changes that lead to improvements in the fill factor of solar cells upon thermal annealing...
May 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28530290/controlling-the-electronic-and-geometric-structures-of-2d-insertions-to-realize-high-performance-metal-insertion-mos2-sandwich-interfaces
#13
Jie Su, Liping Feng, Wei Zeng, Zhengtang Liu
Metal/insertion-MoS2 sandwich interfaces are designed to reduce the Schottky barriers at metal-MoS2 interfaces. The effects of geometric and electronic structures of two-dimensional (2D) insertion materials on the contact properties of metal/insertion-MoS2 interfaces are comparatively studied by first-principles calculations. Regardless of the geometric and electronic structures of 2D insertion materials, Fermi level pinning effects and charge scattering at the metal/insertion-MoS2 interface are weakened due to weak interactions between the insertion and MoS2 layers, no gap states and negligible structural deformations for MoS2 layers...
May 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28530277/advanced-microscopy-and-spectroscopy-reveal-the-adsorption-and-clustering-of-cu-ii-onto-tempo-oxidized-cellulose-nanofibers
#14
Chuantao Zhu, Alexander Soldatov, Aji P Mathew
TEMPO (2,2,6,6-tetramethylpiperidine-1-oxylradical)-mediated oxidation nanofibers (TOCNF), as a biocompatible and bioactive material, have opened up a new application of nanocellulose for the removal of water contaminants. This development demands extremely sensitive and accurate methods to understand the surface interactions between water pollutants and TOCNF. In this report, we investigated the adsorption of metal ions on TOCNF surfaces using experimental techniques atthe nano and molecular scales with Cu(ii) as the target pollutant in both aqueous and dry forms...
May 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28530269/a-critical-comparison-of-coarse-grained-structure-based-approaches-and-atomic-models-of-protein-folding
#15
Jie Hu, Tao Chen, Moye Wang, Hue Sun Chan, Zhuqing Zhang
Structure-based coarse-grained Gō-like models have been used extensively in deciphering protein folding mechanisms because of their simplicity and tractability. Meanwhile, explicit-solvent molecular dynamics (MD) simulations with physics-based all-atom force fields have been applied successfully to simulate folding/unfolding transitions for several small, fast-folding proteins. To explore the degree to which coarse-grained Gō-like models and their extensions to incorporate nonnative interactions are capable of producing folding processes similar to those in all-atom MD simulations, here we systematically compare the computed unfolded states, transition states, and transition paths obtained using coarse-grained models and all-atom explicit-solvent MD simulations...
May 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28530249/large-scale-quantum-emitter-arrays-in-atomically-thin-semiconductors
#16
Carmen Palacios-Berraquero, Dhiren M Kara, Alejandro R-P Montblanch, Matteo Barbone, Pawel Latawiec, Duhee Yoon, Anna K Ott, Marko Loncar, Andrea C Ferrari, Mete Atatüre
Quantum light emitters have been observed in atomically thin layers of transition metal dichalcogenides. However, they are found at random locations within the host material and usually in low densities, hindering experiments aiming to investigate this new class of emitters. Here, we create deterministic arrays of hundreds of quantum emitters in tungsten diselenide and tungsten disulphide monolayers, emitting across a range of wavelengths in the visible spectrum (610-680 nm and 740-820 nm), with a greater spectral stability than their randomly occurring counterparts...
May 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28529964/ultrafast-electron-microscopy-integrated-with-a-direct-electron-detection-camera
#17
Young Min Lee, Young Jae Kim, Ye-Jin Kim, Oh-Hoon Kwon
In the past decade, we have witnessed the rapid growth of the field of ultrafast electron microscopy (UEM), which provides intuitive means to watch atomic and molecular motions of matter. Yet, because of the limited current of the pulsed electron beam resulting from space-charge effects, observations have been mainly made to periodic motions of the crystalline structure of hundreds of nanometers or higher by stroboscopic imaging at high repetition rates. Here, we develop an advanced UEM with robust capabilities for circumventing the present limitations by integrating a direct electron detection camera for the first time which allows for imaging at low repetition rates...
July 2017: Structural Dynamics (Melville, N.Y.)
https://www.readbyqxmd.com/read/28529842/an-environmental-transfer-hub-for-multimodal-atom-probe-tomography
#18
Daniel E Perea, Stephan S A Gerstl, Jackson Chin, Blake Hirschi, James E Evans
Environmental control during transfer between instruments is required for samples sensitive to air or thermal exposure to prevent morphological or chemical changes prior to analysis. Atom probe tomography is a rapidly expanding technique for three-dimensional structural and chemical analysis, but commercial instruments remain limited to loading specimens under ambient conditions. In this study, we describe a multifunctional environmental transfer hub allowing controlled cryogenic or room-temperature transfer of specimens under atmospheric or vacuum pressure conditions between an atom probe and other instruments or reaction chambers...
2017: Advanced Structural and Chemical Imaging
https://www.readbyqxmd.com/read/28529801/crystal-structure-of-n-hy-droxy-quinoline-2-carboxamide-monohydrate
#19
Inna S Safyanova, Kateryna A Ohui, Iryna V Omelchenko, Svitlana V Shyshkina
The title compound, C10H8N2O2·H2O, consists of an N-hy-droxy-quinoline-2-carboxamide mol-ecule in the keto tautomeric form and a water mol-ecule connected through an O-H⋯O hydrogen bond. The N-hy-droxy-quinoline-2-carboxamide mol-ecule has a nearly planar structure [maximum deviation = 0.062 (1) Å] and only the hy-droxy H atom deviates significantly from the mol-ecule plane. In the crystal, π-π stacking between the aromatic rings [inter-centroid distance = 3.887 (1) Å] and inter-molecular O-H⋯O hydrogen bonds organize the crystal components into columns extending along the b-axis direction...
May 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28529800/crystal-structure-and-dft-study-of-8-hy-droxy-1-2-3-5-6-7-hexa-hydro-pyrido-3-2-1-ij-quinoline-9-carbaldehyde
#20
Md Serajul Haque Faizi, Necmi Dege, Maria L Malysheva
In the title compound, C13H15NO2, the fused non-aromatic rings of the julolidine moiety adopt envelope conformations. The hy-droxy group forms an intra-molecular hydrogen bond to the aldehyde O atom, generating an S(6) ring motif. Weak inter-molecular C-H⋯O hydrogen bonds help to stabilize the crystal structure. Density functional theory (DFT) optimized structures at the B3LYP/6-311 G(d,p) level are compared with the experimentally determined mol-ecular structure in the solid state.
May 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
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