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https://www.readbyqxmd.com/read/28102071/temperature-induced-misfolding-in-prion-protein-evidences-of-multiple-partially-disordered-states-stabilized-by-non-native-hydrogen-bonds
#1
Neharika G Chamachi, Suman Chakrabarty
The structural basis of misfolding pathways of a cellular Prion (PrP(C)) into the toxic scrapie form (PrP(SC)) and identification of possible intermediates (e.g. PrP(*)) still eludes us. In this work, we have used a cumulative ~65µs of Replica Exchange Molecular Dynamics simulation data to construct the conformational free energy landscapes and capture the structural and thermodynamic characteristics associated with various stages of the thermal denaturation process in human Prion protein. The temperature dependent free energy surfaces consist of multiple metastable states stabilized by non-native contacts and hydrogen bonds, thus rendering the protein prone towards misfolding...
January 19, 2017: Biochemistry
https://www.readbyqxmd.com/read/28099240/inter-relationship-of-soft-contact-lens-diameter-base-curve-radius-and-fit
#2
Graeme Young, Lee Hall, Anna Sulley, Kathrine Osborn-Lorenz, James S Wolffsohn
PURPOSE: To evaluate the inter-relationship of soft contact lens base curve radius (BC), diameter, and lens fit using a mathematical model. METHODS: A spreadsheet mathematical model was used to evaluate theoretical fitting characteristics for various combinations of soft lens BC and diameter. The designs were evaluated using ocular topography data collected from 163 UK subjects. The model evaluated lens tightness (edge strain) and on-eye diameter (horizontal corneal overlap) and assumed that acceptable values fell within the range 0 to 6% and 0...
January 18, 2017: Optometry and Vision Science: Official Publication of the American Academy of Optometry
https://www.readbyqxmd.com/read/28098324/ionic-screening-and-dissociation-are-crucial-for-understanding-chemical-self-propulsion-in-polar-solvents
#3
Aidan T Brown, Wilson C K Poon, Christian Holm, Joost de Graaf
Polar solvents like water support the bulk dissociation of themselves and their solutes into ions, and the re-association of these ions into neutral molecules in a dynamic equilibrium, e.g., H2O2 ⇌ H(+) + HO2(-). Using continuum theory, we study the influence of these association-dissociation reactions on the self-propulsion of colloids driven by surface chemical reactions (chemical swimmers). We find that association-dissociation reactions should have a strong influence on swimmers' behaviour, and therefore should be included in future modelling...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28098313/the-glass-transition-and-interfacial-dynamics-of-single-strand-fibers-of-polymers
#4
Hyun Woo Cho, Bong June Sung
We investigate the glass transition and interfacial dynamics of single strand fibers of flexible polymers by employing molecular dynamics (MD) simulations along with a coarse grained model. While the polymer fiber has drawn significant attention due to its applicability in tissue engineering and stretchable electronics, its dynamic properties, especially the glass transition temperature (Tg), are yet to be understood at the molecular level. For example, there has been a controversy on the effect of the polymer fiber radius (R) on Tg: Tg decreased with a decrease in R for some polymer fibers, whereas Tg of other polymer fibers was not sensitive to R...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28098282/b40-cluster-stability-reactivity-and-its-planar-structural-precursor
#5
Yang Yang, Zhuhua Zhang, Evgeni S Penev, Boris I Yakobson
We report a comprehensive first-principles study of the structural and chemical properties of the recently discovered B40 cage. It is found to be highly reactive and can exothermically dimerize, regardless of the orientation, by overcoming a small energy barrier ≃0.06 eV. The energy gap of the system varies widely with the aggregation of the increasing number of B40 cages, from 3.14 eV in a single B40, to 1.54 eV in the dimer, to 1.25 eV in the trimer. We also explore a recipe for protecting the B40 cage by sheathing it within a carbon shell and identify carbon nanotubes with a radius of ∼6 Å as optimal hosts for an isolated cage...
January 18, 2017: Nanoscale
https://www.readbyqxmd.com/read/28097869/a-solvent-free-processable-and-photo-patternable-hybrid-gate-dielectric-for-flexible-top-gate-organic-field-effect-transistors
#6
Jun Seon Kwon, Han-Wool Park, Do Hwan Kim, Young-Je Kwark
We report a novel solvent-free and direct photo-patternable poly[(mercaptopropyl)methyl-siloxane] (PMMS) hybrid dielectric for flexible top-gate organic field-effect transistors (OFETs), utilizing a photo-activated thiol-ene reaction under UV irradiation of 254 nm to induce cross-linking, even in air and at low temperature. In particular, a solvent-free PMMS-f dielectric film, for which an optimal cross-linking density is shown by a well-organized molar ratio between thiol and vinyl in the thiol-ene reaction, exhibited a high dielectric constant (5...
January 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28097537/optimization-of-a-new-aerodynamic-cylindrical-faims-device-for-small-molecule-analysis
#7
Randy W Purves, Satendra Prasad, Michael Belford, Albert Vandenberg, Jean-Jacques Dunyach
The implementation of an aerodynamic mechanism to improve ion sampling between nanoelectrospray (n-ESI) and FAIMS was recently reported for proteomic analyses. This investigation explores the new FAIMS interface for small molecule analysis at high liquid flow rates and includes an examination of key differences in ionization between heated-ESI (HESI) and n-ESI. The sheath gas, critical for desolvation with HESI, affects FAIMS operation as higher FAIMS gas flow rates are required to achieve sufficient desolvation...
January 17, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28095691/micrometer-scale-ion-current-rectification-at-polyelectrolyte-brush-modified-micropipettes
#8
Xiulan He, Kailin Zhang, Ting Li, Yanan Jiang, Ping Yu, Lanqun Mao
Here we for the first time report that ion current rectification (ICR) could be observed at micrometer scale in symmetric electrolyte solution with polyimidazolium brush (PimB)-modified micropipettes, which is defined as micron ion current rectification (MICR). To qualitatively understand MICR, a three-layer model including charged layer, double layer and bulk layer is proposed, which could also be extended to understand the ICR at nanoscale. Based on this model, we propose when the charge in charged layer is comparable with that in the bulk layer, the ICR would occur no matter whether the electric double layer is overlapped...
January 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28095112/autogenous-bone-particle-titanium-fibre-composites-for-bone-regeneration-in-a-rabbit-radius-critical-size-defect-model
#9
Huanxin Xie, Ye Ji, Qi Tian, Xintao Wang, Nan Zhang, Yicai Zhang, Jun Xu, Nanxiang Wang, Jinglong Yan
PURPOSE: To explore the effects of autogenous bone particle/titanium fibre composites on repairing segmental bone defects in rabbits. MATERIALS AND METHODS: A model of bilateral radial bone defect was established in 36 New Zealand white rabbits which were randomly divided into 3 groups according to filling materials used for bilaterally defect treatment: in group C, 9 animal bone defect areas were prepared into simple bilateral radius bone defect (empty sham) as the control group; 27 rabbits were used in groups ABP and ABP-Ti...
January 17, 2017: Connective Tissue Research
https://www.readbyqxmd.com/read/28093906/floating-and-sinking-of-a-pair-of-spheres-at-a-liquid-fluid-interface
#10
Himantha Cooray, Pietro Cicuta, Dominic Vella
Spheres floating at liquid--fluid interfaces cause interfacial deformations such that their weight is balanced by the resultant forces of surface tension and hydrostatic pressure, whilst also satisfying a contact angle condition. Determining the meniscus shape around several floating spheres is a complicated problem because the vertical locations of the spheres and the horizontal projections of the three--phase contact lines are not known a priori. Here, a new computational algorithm is developed to simultaneously satisfy the nonlinear Laplace--Young equation for the meniscus shape, the vertical force balance, and the geometric properties of the spheres...
January 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28089796/correlationbetweenobesity-and-severity-of-distal-radius-fractures
#11
Carlos Acosta-Olivo, Juan C Gonzalez-Saldivar, Gregorio Villarreal-Villarreal, Alejandro Torres-Botello, Eduardo Gomez-Garcia, Yadira Tamez-Mata, Victor Peña-Martinez
INTRODUCTION: The incidence of obesity has increased significantly worldwide. Our hypothesis was that patients with obesity have a more severe distal radius fracture andwe realized a study to evaluate this correlation between obesity and severity of distal radius fractures caused by low-energy injuries. MATERIALS AND METHODS: A total of 114 patients with distal radius fracture were examined in a cross-sectional, observational study. Fractures were classified according to the international AO-Müller/Orthopedic Trauma Association (AO/OTA) classification in order to determine the severity...
January 9, 2017: Orthopaedics & Traumatology, Surgery & Research: OTSR
https://www.readbyqxmd.com/read/28089163/fragment-specific-fixation-versus-volar%C3%A2-locking-plates-in-primarily-nonreducible-or-secondarily-redisplaced%C3%A2-distal-radius-fractures-a%C3%A2-randomized-controlled-study
#12
Marcus Landgren, Antonio Abramo, Mats Geijer, Philippe Kopylov, Magnus Tägil
PURPOSE: To compare the patient-reported, clinical, and radiographic outcome of 2 methods of internal fixation in distal radius fractures. METHODS: Fifty patients, mean age 56 years (range, 21-69 years) with primarily nonreducible or secondarily redisplaced distal radius fractures were randomized to open reduction internal fixation using volar locking plates (n = 25) or fragment-specific fixation (n = 25). The patients were assessed on grip strength, range of motion, patient-reported outcome (Quick Disabilities of the Arm, Shoulder, and Hand), pain (visual analog scale), health-related quality of life (Short Form-12 [SF-12]), and radiographic evaluation...
January 11, 2017: Journal of Hand Surgery
https://www.readbyqxmd.com/read/28088847/vapor-and-gas-bubble-growth-dynamics-around-laser-irradiated-water-immersed-plasmonic-nanoparticles
#13
Yuliang Wang, Mikhail E Zaytsev, Hai Le The, Jan Cornelis Titus Eijkel, Harold J W Zandvliet, Xuehua Zhang, Detlef Lohse
Microbubbles produced by exposing water-immersed metallic nanoparticles to resonant light play an important role in novel and efficient plasmonic-enhanced processes for catalytic conversion, solar energy harvesting, biomedical imaging technique or cancer therapy. How do these bubbles form and what is their gas composition? In this article, the growth dynamics of nucleating bubbles around laser irradiated water-immersed Au plasmonic nanoparticles are studied to determine the exact origin of the occurrence and growth of these bubbles...
January 16, 2017: ACS Nano
https://www.readbyqxmd.com/read/28088646/bone-microarchitecture-in-adolescent-boys-with-autism-spectrum-disorder
#14
Ann M Neumeyer, Natalia Cano Sokoloff, Erin McDonnell, Eric A Macklin, Christopher J McDougle, Madhusmita Misra
BACKGROUND: Boys with autism spectrum disorder (ASD) have lower areal bone mineral density (aBMD) than typically developing controls (TDC). Studies of volumetric BMD (vBMD) and bone microarchitecture provide information about fracture risk beyond that provided by aBMD but are currently lacking in ASD. OBJECTIVES: To assess ultradistal radius and distal tibia vBMD, bone microarchitecture and strength estimates in adolescent boys with ASD compared to TDC. DESIGN/METHODS: Cross-sectional study of 34 boys (16 ASD, 18 TDC) that assessed (i) aBMD at the whole body (WB), WB less head (WBLH), hip and spine using dual X-ray absorptiometry (DXA), (ii) vBMD and bone microarchitecture at the ultradistal radius and distal tibia using high-resolution peripheral quantitative CT (HRpQCT), and (iii) bone strength estimates (stiffness and failure load) using micro-finite element analysis (FEA)...
January 11, 2017: Bone
https://www.readbyqxmd.com/read/28088481/saxs-structural-studies-of-dps-from-deinococcus-radiodurans-highlights-the-conformation-of-the-mobile-n-terminal-extensions
#15
Sandra P Santos, Maxime G Cuypers, Adam Round, Stephanie Finet, Theyencheri Narayanan, Edward P Mitchell, Célia V Romão
The radiation resistant bacterium Deinococcus radiodurans contains two DNA binding proteins from starved cells (Dps): Dps1 (DR2263) and Dps2 (DRB0092). These are suggested to play a role in DNA interaction, manganese and iron storage. The proteins assemble as a conserved dodecameric structure with structurally uncharacterized N-terminal extensions. In the case of DrDps1 these extensions have been proposed to be involved in DNA interactions, while in DrDps2 their function has yet to be established. The reported data reveals the relative position of the N-terminal extensions to the dodecameric sphere in solution for both Dps...
January 11, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28087990/the-modification-of-onsager-reaction-field-and-its-application-on-spectral-parameters
#16
Xinyu Wang, Rina Dao, Jia Yao, De Peng, Haoran Li
Solvent polarity is an important solvent property. The Onsager's theory of reaction field was the most classic model to describe the solvent effects and was widely used in relating dielectric constant and other solvent polarity parameters. In this study, a modified semi-empirical reaction field was presented to relate electron transition energies or hyperfine coupling constants with the dielectric constants of solvents. In previous works, this relationship was well established by traditional Onsager reaction field for non-hydrogen bonding systems but failed for hydrogen bonding systems...
January 14, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28087638/intrinsic-properties-of-limb-bud-cells-can-be-differentially-reset
#17
Patricia Saiz-Lopez, Kavitha Chinnaiya, Matthew Towers, Maria A Ros
An intrinsic timing mechanism specifies the positional values of the zeugopod (i.e. radius/ulna) and then autopod (i.e. wrist/digits) segments during limb development. Here we have addressed if this timing mechanism ensures that patterning events occur only once by grafting GFP-expressing autopod progenitor cells to the earlier host signaling environment of zeugopod progenitor cells. We show that early and late autopod progenitors fated for the wrist and phalanges, respectively, both contribute to the entire host autopod indicating that the autopod positional value is irreversibly determined as revealed by Hoxa13 expression...
January 13, 2017: Development
https://www.readbyqxmd.com/read/28081239/statistical-modeling-applied-to-deformation-relaxation-processes-in-a-composite-biopolymer-network-induced-by-magnetic-field
#18
Javier Tarrío-Saavedra, Cécilia Galindo González, Salvador Naya, Jorge López-Beceiro, Alain Ponton
This study investigated a methodology based on image processing and statistics to characterize and model the deformation upon controlled and uniform magnetic field and the relaxation under zero field of droplets observed in aqueous solutions of sodium alginate incorporating magnetic maghemite nanoparticles stabilized by adsorption of citrate ions. The changes of droplet geometry were statistically analyzed using a new approach based on the data obtained from optical microscopy, image processing, nonlinear regression, evolutionary optimization, analysis of variance and resampling...
2017: PloS One
https://www.readbyqxmd.com/read/28081097/laser-beam-self-focusing-in-turbulent-dissipative-media
#19
B Hafizi, J R Peñano, J P Palastro, R P Fischer, G DiComo
A high-power laser beam propagating through a dielectric in the presence of fluctuations is subject to diffraction, dissipation, and optical Kerr nonlinearity. A method of moments was applied to a stochastic, nonlinear enveloped wave equation to analyze the evolution of the long-term spot radius. For propagation in atmospheric turbulence described by a Kolmogorov-von Kármán spectral density, the analysis was benchmarked against field experiments in the low-power limit and compared with simulation results in the high-power regime...
January 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28078409/determination-of-molecular-size-parameters-and-quantification-of-polyacrylic-acid-by-high-performance-size-exclusion-chromatography-with-triple-detection
#20
Jean-François Cotte, Afifa Bouadam, Agathe Sordoillet, Isabelle Jaudinaud, Véronique Chambon, Philippe Talaga
Synthetic polyelectrolytes are a broad class of vaccine adjuvants. Among them, polyacrylic acid (PAA), a polyanionic polymer, is currently evaluated by Sanofi Pasteur. As chain length is considered to be a critical quality attribute for adjuvant properties of PAA, measurement of precise and accurate molecular size parameters is important for these polymers. In the field of synthetic polymer chemistry, methods for determination of molecular size parameters are well defined. Specifically, high performance size-exclusion chromatography (HPSEC) with multi-detection system is a method of choice...
January 11, 2017: Analytical and Bioanalytical Chemistry
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