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https://www.readbyqxmd.com/read/28432776/exploring-non-obvious-hydrophobic-binding-pockets-on-protein-surfaces-increasing-affinities-in-peptide-protein-interactions
#1
Lars Baltzer, Aleksandra Balliu
A 42-residue polypeptide conjugated to a small organic molecule capable of targeting the phosphorylated side chain of Ser-15 was shown to bind glycogen phosphorylase a (GPa) with a KD of 280 nM. The replacement of hydrophobic amino acids by Ala reduced affinities, whereas the incorporation of L-2-aminooctanoic acid (Aoc) increased affinities. Replacing Nle-5, Ile-9 and Leu-12 by Aoc reduced the KD from 280 nM to 27 nM. Downsizing the 42-mer to an 11-mer gave rise to an order of magnitude lower affinity for GPa but the 11-mer where Nle-5, Ile-9 and Leu-12 were replaced by Aoc showed a KD of 550 nM, comparable to that of the parent 42-mer...
April 22, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28432558/resolved-parental-infertility-and-children-s-educational-achievement
#2
Amelia R Branigan, Jonas Helgertz
Although difficulty conceiving a child has long been a major medical and social preoccupation, it has not been considered as a predictor of long-term outcomes in children ultimately conceived. This is consistent with a broader gap in knowledge regarding the consequences of parental health for educational performance in offspring. Here we address that omission, asking how resolved parental infertility relates to children's academic achievement. In a sample of all Swedish births between 1988 and 1995, we find that involuntary childlessness prior to either a first or a second birth is associated with lower academic achievement (both test scores and GPA) in children at age 16, even if the period of infertility was prior to a sibling's birth rather than the child's own...
April 21, 2017: Demography
https://www.readbyqxmd.com/read/28430478/premelting-hcp-to-bcc-transition-in-beryllium
#3
Y Lu, T Sun, Ping Zhang, P Zhang, D-B Zhang, R M Wentzcovitch
Beryllium (Be) is an important material with wide applications ranging from aerospace components to x-ray equipment. Yet a precise understanding of its phase diagram remains elusive. We have investigated the phase stability of Be using a recently developed hybrid free energy computation method that accounts for anharmonic effects by invoking phonon quasiparticles. We find that the hcp → bcc transition occurs near the melting curve at 0<P<11  GPa with a positive Clapeyron slope of 41±4  K/GPa, which is more consistent with recent experimental measurements...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28430195/a-stable-compound-of-helium-and-sodium-at-high-pressure
#4
Xiao Dong, Artem R Oganov, Alexander F Goncharov, Elissaios Stavrou, Sergey Lobanov, Gabriele Saleh, Guang-Rui Qian, Qiang Zhu, Carlo Gatti, Volker L Deringer, Richard Dronskowski, Xiang-Feng Zhou, Vitali B Prakapenka, Zuzana Konôpková, Ivan A Popov, Alexander I Boldyrev, Hui-Tian Wang
Helium is generally understood to be chemically inert and this is due to its extremely stable closed-shell electronic configuration, zero electron affinity and an unsurpassed ionization potential. It is not known to form thermodynamically stable compounds, except a few inclusion compounds. Here, using the ab initio evolutionary algorithm USPEX and subsequent high-pressure synthesis in a diamond anvil cell, we report the discovery of a thermodynamically stable compound of helium and sodium, Na2He, which has a fluorite-type structure and is stable at pressures >113 GPa...
May 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28429408/mo2-b4-o9-connecting-borate-and-metal-cluster-chemistry
#5
Martin K Schmitt, Oliver Janka, Rainer Pöttgen, Christopher Benndorf, Marcos de Oliveira, Hellmut Eckert, Florian Pielnhofer, Amadeus-Samuel Tragl, Richard Weihrich, Bastian Joachim, Dirk Johrendt, Hubert Huppertz
We report on the first thoroughly characterized molybdenum borate, which was synthesized in a high-pressure/high-temperature experiment at 12.3 GPa/1300 °C using a Walker-type multianvil apparatus. Mo2 B4 O9 incorporates tetrahedral molybdenum clusters into an anionic borate crystal structure-a structural motif that has never been observed before in the wide field of borate crystal chemistry. The six bonding molecular orbitals of the [Mo4 ] tetrahedron are completely filled with 12 electrons, which are fully delocalized over the four molybdenum atoms...
April 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28426190/robust-polymer-electrolyte-membranes-with-high-ambient-temperature-lithium-ion-conductivity-via-polymerization-induced-microphase-separation
#6
Sujay A Chopade, Jesus G Au, Ziang Li, Peter W Schmidt, Marc A Hillmyer, Timothy P Lodge
Mechanically robust polymer electrolyte membranes (PEMs) exhibiting high ionic conductivity at ambient temperature are a prerequisite for next-generation electrochemical devices. We utilized a polymerization-induced microphase separation (PIMS) strategy to prepare nanostructured materials comprising continuous conducting nanochannels intertwined with a mechanically and thermally robust cross-linked polymeric framework. Addition of succinonitrile (SN) rendered the poly(ethylene oxide)/lithium (Li) salt conducting domains completely amorphous, resulting in outstanding conductivities (∼0...
April 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28425715/five-fold-ordering-in-high-pressure-perovskites-rmn3o6-r-gd-tm-and-y
#7
Lei Zhang, Yoshitaka Matsushita, Kazunari Yamaura, Alexei A Belik
Cation and anion ordering plays an important role in the properties of materials, in particular, in the properties of perovskite materials. Here we report on unusual 5-fold cation/charge ordering in high-pressure-synthesized (at 6 GPa and ∼1670 K) RMn3O6 perovskites with R = Gd-Tm and Y. R(3+), Mn(2+), and Mn(3+) cations are ordered at the A site in two separate chains consisting of R(3+) and alternating Mn(2+) (in tetrahedral coordination) and Mn(3+) (in square-planar coordination), while Mn(3+) and mixed-valent Mn(3+)/Mn(4+) are ordered at the B site in layers...
April 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28425698/-dispersion-assembly-approach-to-synthesize-three-dimensional-graphene-polymer-composite-aerogel-as-a-powerful-organic-cathode-for-rechargeable-li-and-na-batteries
#8
Yu Zhang, Yanshan Huang, Guanhui Yang, Fanxing Bu, Ke Li, Imran Shakir, Yuxi Xu
Polymer cathode materials are promising alternatives to inorganic counterparts for both lithium ion batteries (LIBs) and sodium ion batteries (SIBs) due to their high theoretical capacity, adjustable molecular structure and strong adaptability to different counter-ions in batteries, etc. However, they suffer from poor practical capacity and low rate capability because of their intrinsically poor conductivity. Herein, we report the synthesis of self-assembled graphene/poly(anthraquinonyl sufide) (PAQS) composite aerogel (GPA) with efficient integration of three-dimensional (3D) graphene framework with electroactive PAQS particles via a novel dispersion-assembly strategy, which can be used as a free-standing flexible cathode upon mechanical pressing...
April 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28422488/pressure-driven-isostructural-phase-transition-in-innbo4-in-situ-experimental-and-theoretical-investigations
#9
Alka B Garg, Daniel Errandonea, Catalin Popescu, Domingo Martinez-García, Julio Pellicer-Porres, Placida Rodríguez-Hernández, Alfonso Muñoz, Pablo Botella, Vanesa P Cuenca-Gotor, Juan Angel Sans
The high-pressure behavior of technologically important visible-light photocatalytic semiconductor InNbO4, adopting a monoclinic wolframite-type structure at ambient conditions, was investigated using synchrotron-based X-ray diffraction, Raman spectroscopic measurements, and first-principles calculations. The experimental results indicate the occurrence of a pressure-induced isostructural phase transition in the studied compound beyond 10.8 GPa. The large volume collapse associated with the phase transition and the coexistence of two phases observed over a wide range of pressure shows the nature of transition to be first-order...
April 19, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28420847/the-successful-treatment-of-myeloperoxidase-antineutrophil-cytoplasmic-antibody-positive-hypertrophic-pachymeningitis-in-patients-with-the-limited-form-of-granulomatosis-with-polyangiitis-using-methotrexate-two-case-reports
#10
Shinjiro Kaieda, Naomi Yoshida, Midori Minezaki, Shuri Ushijima, Daisuke Wakasugi, Shiroh Miura, Yusuke Uchiyama, Hiroaki Ida, Tomoaki Hoshino
Recent findings have indicated a close relationship between myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-positive hypertrophic pachymeningitis and the limited form of granulomatosis with polyangiitis (GPA). In Japan, MPO-ANCA-positive hypertrophic pachymeningitis predominantly occurs in elderly individuals. We herein describe the cases of two patients with MPO-ANCA-positive hypertrophic pachymeningitis associated with the limited form of GPA who were successfully treated with a combination of corticosteroids and methotrexate...
2017: Internal Medicine
https://www.readbyqxmd.com/read/28418017/accessing-forbidden-glass-regimes-through-high-pressure-sub-tg-annealing
#11
Mouritz N Svenson, John C Mauro, Sylwester J Rzoska, Michal Bockowski, Morten M Smedskjaer
Density and hardness of glasses are known to increase upon both compression at the glass transition temperature (Tg) and ambient pressure sub-Tg annealing. However, a serial combination of the two methods does not result in higher density and hardness, since the effect of compression is countered by subsequent annealing and vice versa. In this study, we circumvent this by introducing a novel treatment protocol that enables the preparation of high-density, high-hardness bulk aluminosilicate glasses. This is done by first compressing a sodium-magnesium aluminosilicate glass at 1 GPa at Tg, followed by sub-Tg annealing in-situ at 1 GPa...
April 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28417957/attractive-force-driven-superhardening-of-graphene-membranes-as-a-pin-point-breaking-of-continuum-mechanics
#12
Makoto Ashino, Roland Wiesendanger
Bending at the nanometre scale can substantially modify the mechanical, chemical and electronic properties of graphene membranes. The subsequent response of chemical bonds leads to deviations from plate idealisation in continuum mechanics. However, those phenomena have thus far been investigated exclusively by measuring the electronic properties of graphene deformed by compressing and stretching with local-probe techniques. Here, we report that the interatomic-attractive forces applied on the convexly-curved graphene by the probe tip give rise to a pin-point breaking of the plate idealisation in the continuum mechanics, facilitating atomically-localised enhancements in its chemical reactivity and mechanical strength...
April 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28416793/seismic-anisotropy-of-the-d%C3%A2-layer-induced-by-001-deformation-of-post-perovskite
#13
Xiang Wu, Jung-Fu Lin, Pamela Kaercher, Zhu Mao, Jin Liu, Hans-Rudolf Wenk, Vitali B Prakapenka
Crystallographic preferred orientation (CPO) of post-perovskite (Mg,Fe)SiO3 (pPv) has been believed to be one potential source of the seismic anisotropic layer at the bottom of the lower mantle (D″ layer). However, the natural CPO of pPv remains ambiguous in the D″ layer. Here we have carried out the deformation experiments of pPv-(Mg0.75,Fe0.25)SiO3 using synchrotron radial X-ray diffraction in a membrane-driven laser-heated diamond anvil cell from 135 GPa and 2,500 K to 154 GPa and 3,000 K. Our results show that the intrinsic texture of pPv-(Mg0...
April 18, 2017: Nature Communications
https://www.readbyqxmd.com/read/28410253/factors-associated-with-visual-field-progression-in-cirrus-optical-coherence-tomography-guided-progression-analysis-a-topographic-approach
#14
Joong Won Shin, Kyung Rim Sung, Jiyun Lee, Junki Kwon
PURPOSE: To identify factors associated with visual field (VF) progression in optical coherence tomography (OCT)-guided progression analysis (GPA) using a topographic approach. METHODS: Topographic components of OCT-GPA maps (Cirrus HD-OCT; Carl Zeiss Meditec) were classified according to location (temporal, superotemporal, superonasal, nasal, inferornasal, and inferotemporal), size (small, medium, and large), shape (wedge and irregular types), and pattern of retinal nerve fiber layer (RNFL) progression (widening, deepening, and new development)...
April 13, 2017: Journal of Glaucoma
https://www.readbyqxmd.com/read/28407712/relationship-between-young-s-modulus-and-film-architecture-in-cellulose-nanofibril-based-multilayered-thin-films
#15
Firas Azzam, Laurent Chaunier, Céline Moreau, Denis Lourdin, Patricia Bertoncini, Bernard Cathala
Young's moduli of cellulose nanofibril (CNF)-poly(allylamine hydrochloride) (PAH) multilayered thin films were measured using strain-induced elastic buckling instability for mechanical measurements (SIEBIMM) and the quantitative nanomechanical mapping technique (PF-QNM). To establish the relationship between structure and mechanical properties, three types of films with various architectures were built using the layer-by-layer method by changing the ionic strength of the dipping solution. Both methods demonstrate that the architecture of a film has a strong impact on its mechanical properties even though the film has similar cellulose content, emphasizing the role of the architecture...
April 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28405005/carbon-bearing-silicate-melt-at-deep-mantle-conditions
#16
Dipta B Ghosh, Suraj K Bajgain, Mainak Mookherjee, Bijaya B Karki
Knowledge about the incorporation and role of carbon in silicate magmas is crucial for our understanding of the deep mantle processes. CO2 bearing silicate melting and its relevance in the upper mantle regime have been extensively explored. Here we report first-principles molecular dynamics simulations of MgSiO3 melt containing carbon in three distinct oxidation states - CO2, CO, and C at conditions relevant for the whole mantle. Our results show that at low pressures up to 15 GPa, the carbon dioxide speciation is dominated by molecular form and carbonate ions...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28402319/pressure-induced-structural-and-spin-transitions-of-fe3s4
#17
Shengxuan Huang, Duan Kang, Xiang Wu, Jingjing Niu, Shan Qin
Greigite (Fe3S4), isostructural with Fe3O4 has recently attracted great scientific interests from material science to geology due to its complicated structure and electronic and magnetic configurations. Here, an investigation into the structural, magnetic and electronic properties of Fe3S4 under high pressure has been conducted by first-principle calculations based on density functional theory. The results show that a first-order phase transition of Fe3S4 would occur from the inverse spinel (SP) structure to the Cr3S4-type (CS) structure at 3...
April 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28401904/intercalant-independent-transition-temperature-in-superconducting-black-phosphorus
#18
R Zhang, J Waters, A K Geim, I V Grigorieva
Research on black phosphorus has been experiencing a renaissance over the last years, after the demonstration that few-layer crystals exhibit high carrier mobility and a thickness-dependent bandgap. Black phosphorus is also known to be a superconductor under high pressure exceeding 10 GPa. The superconductivity is due to a structural transformation into another allotrope and accompanied by a semiconductor-metal transition. No superconductivity could be achieved for black phosphorus in its normal orthorhombic form, despite several reported attempts...
April 12, 2017: Nature Communications
https://www.readbyqxmd.com/read/28400579/water-carbon-dioxide-solid-phase-equilibria-at-pressures-above-4-gpa
#19
E H Abramson, O Bollengier, J M Brown
A solid phase in the mixed water-carbon dioxide system, previously identified as carbonic acid, was observed in the high-pressure diamond-anvil cell. The pressure-temperature paths of both its melting and peritectic curves were measured, beginning at 4.4 GPa and 165 °C (where it exists in a quadruple equilibrium, together with an aqueous fluid and the ices H2O(VII) and CO2(I)) and proceeding to higher pressures and temperatures. Single-crystal X-ray diffraction revealed a triclinic crystal with unit cell parameters (at 6...
April 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28398041/pressure-induced-stable-beryllium-peroxide
#20
Shoutao Zhang, Fei Li, Haiyang Xu, Guochun Yang
Beryllium oxides, at ambient pressure, have been extensively studied due to their unique chemical bonds and applications. However, the long-desirable target beryllium peroxide (BeO2) has not been reported, thus far. Currently, the application of pressure has become a powerful tool in finding unusual stoichiometric compounds with exotic properties. Here, swarm structural searches in combination with first-principles calculations disclosed that the reaction of BeO and oxygen, at pressures above 89.6 GPa, yields BeO2...
April 11, 2017: Inorganic Chemistry
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