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Yifan Bu, Yinglu Cui, Ying Peng, Meirong Hu, Yu'e Tian, Yong Tao, Bian Wu
Xylanases, which cleave the β-1,4-glycosidic bond between xylose residues to release xylooligosaccharides (XOS), are widely used as food additives, animal feeds, and pulp bleaching agents. However, the thermally unstable nature of xylanases would hamper their industrial application. In this study, we used in silico design in a glycoside hydrolase family (GH) 11 xylanase to stabilize the enzyme. A combination of the best mutations increased the apparent melting temperature by 14 °C and significantly enhanced thermostability and thermoactivation...
April 2018: Applied Microbiology and Biotechnology
Peter Westh, Kim Borch, Trine Sørensen, Radina Tokin, Jeppe Kari, Silke Badino, Mafalda A Cavaleiro, Nanna Røjel, Stefan Christensen, Cynthia S Vesterager, Corinna Schiano-di-Cola
We have measured activity and substrate affinity of the thermostable cellobiohydrolase, Cel7A, from Rasamsonia emersonii over a broad range of temperatures. For the wild type enzyme, which does not have a Carbohydrate Binding Module (CBM), higher temperature only led to moderately increased activity against cellulose, and we ascribed this to a pronounced, temperature induced desorption of enzyme from the substrate surface. We also tested a "high affinity" variant of R. emersonii Cel7A with a linker and CBM from a related enzyme...
April 2018: Biotechnology and Bioengineering
Lei Zhou, Ya Zhang, Rongrong Ying, Guoqing Wang, Tao Long, Jianhua Li, Yusuo Lin
The widespread occurrence of organophosphorus pesticides (OPPs) in the environment poses risks to both ecologic system as well as human health. This study investigated the oxidation kinetics of chlorpyrifos (CP), one of the typical OPPs, by thermoactivated persulfate (PS) oxidation process, and evaluated the influence of key kinetic factors, such as PS concentrations, pH, temperature, bicarbonate, and chloride ions. The reaction pathways and mechanisms were also proposed based on products identification by LC-MS techniques...
April 2017: Environmental Science and Pollution Research International
Boyuan Zhang, M Tuan Trinh, Brandon Fowler, Melissa Ball, Qizhi Xu, Fay Ng, Michael L Steigerwald, X-Y Zhu, Colin Nuckolls, Yu Zhong
Organic photodetectors (OPDs) are attractive for their high optical absorption coefficient, broad wavelength tunability, and compatibility with lightweight and flexible devices. Here we describe a new molecular design that enables high performance organic photodetectors. We use a rigid, conjugated macrocycle as the electron acceptor in devices to obtain high photocurrent and low dark current. We make a direct comparison between the devices made with the macrocyclic acceptor and an acyclic control molecule; we find that the superior performance of the macrocycle originates from its rigid, conjugated, and cyclic structure...
December 21, 2016: Journal of the American Chemical Society
S N Letuta, S N Pashkevich, A T Ishemgulov, Yu D Lantukh, E K Alidzhanov, S S Sokabaeva, V V Bryukhanov
The features of delayed fluorescence (DF) and phosphorescence in erythrosine stained healthy and cancer-diseased mammary gland tissues of BYRB-line mice were investigated in vitro. Thermoactivated delayed fluorescence (TDF), triplet-triplet annihilation (TTA) and originated from singlet-triplet annihilation (STA) delayed fluorescence are investigated as competing channels of radiative relaxation of the triplet states of erythrosine. The dominant role of diffusive-mobile molecular oxygen in deactivation of triplet-excited long-live states of the dye molecules in cells is determined...
October 2016: Journal of Photochemistry and Photobiology. B, Biology
Byung Hoon Jo, Tae Yoon Park, Hyun June Park, Young Joo Yeon, Young Je Yoo, Hyung Joon Cha
Exploiting carbonic anhydrase (CA), an enzyme that rapidly catalyzes carbon dioxide hydration, is an attractive biomimetic route for carbon sequestration due to its environmental compatibility and potential economic viability. However, the industrial applications of CA are strongly hampered by the unstable nature of enzymes. In this work, we introduced in silico designed, de novo disulfide bond in a bacterial α-type CA to enhance thermostability. Three variants were selected and expressed in Escherichia coli with an additional disulfide bridge...
2016: Scientific Reports
E V Safonova, Yu P Mitrofanov, R A Konchakov, A Yu Vinogradov, N P Kobelev, V A Khonik
The only intrinsic point defects of simple crystalline metals known from solid state physics are vacancies and interstitials. It is widely believed that while vacancies play a major role in crystal properties and their concentration reaches relatively big values near the melting temperature T m, interstitials essentially do not occur in thermodynamic equilibrium and their influence on properties is minor. Here, taking aluminum single crystals as an example, we present compelling experimental evidence for rapid thermoactivated growth of interstitial concentration upon approaching T m...
June 2, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Fausto Silva Bramante, Francisco Machado da Fonseca Junior, Célia Regina Maio Pinzan-Vercelino, Júlio de Araújo Gurgel, Rudys Rodolfo de Jesus Tavarez, Etevaldo Matos Maia Filho, Mateus Rodrigues Tonetto, Alvaro Henrique Borges, Matheus Coelho Bandéca
OBJECTIVE: This study evaluated in vitro the mechanical changes of 0.018" (0.45 mm) and 0.016 × 0.022" (0.40 × 0.55 mm) thermoactivated nickel-titanium archwires subjected to heat treatment on their distal ends. MATERIALS AND METHODS: Ten archwires in diameters 0.018" and 0.016 × 0.022" by different manufacturers Ormco, Morelli, Orthometric and Unitek were tested. Each tested archwire had an experimental side, submitted to heat treatment, and an annealing-free control...
February 1, 2015: Journal of Contemporary Dental Practice
Lingyi Meng, Dong Wang, Qikai Li, Yuanping Yi, Jean-Luc Brédas, Zhigang Shuai
We describe a new dynamic Monte Carlo model to simulate the operation of a polymer-blend solar cell; this model provides major improvements with respect to the one we developed earlier [J. Phys. Chem. B 114, 36 (2010)] by incorporating the Poisson equation and a charge thermoactivation mechanism. The advantage of the present approach is its capacity to deal with a nonuniform electrostatic potential that dynamically depends on the charge distribution. In this way, the unbalance in electron and hole mobilities and the space-charge induced potential distribution can be treated explicitly...
March 28, 2011: Journal of Chemical Physics
Patrick Ginet, Kevin Montagne, Sho Akiyama, Ali Rajabpour, Akiyoshi Taniguchi, Teruo Fujii, Yasuyuki Sakai, Beomjoon Kim, Dominique Fourmy, Sebastian Volz
Metal electrodes with micron scale width enable the heating of less than a dozen cells in a confluent layer at predictable temperatures up to 85 °C with an accuracy of ±2 °C. Those performances were obtained by a preliminary robust temperature calibration based on biotin-rhodamine fluorescence and by controlling the temperature map on the substrate through thermal modeling. The temperature accuracy was proved by inducing the expression of heat shock proteins (HSP) in a few NIH-3T3 cells through a confined and precise temperature rise...
April 21, 2011: Lab on a Chip
D Alloyeau, G Prévot, Y Le Bouar, T Oikawa, C Langlois, A Loiseau, C Ricolleau
Ostwald ripening has been broadly studied because it plays a determinant role in the evolution of cluster size during both chemical and physical synthesis of nanoparticles. This thermoactivated process causes large particles to grow, drawing material from the smaller particles, which shrink. However, this phenomenon becomes more complex when considering the coarsening of metallic alloy clusters. The present experimental and theoretical investigations show that the relative composition of CoPt nanoparticles can be strongly modified during high temperature annealing and displays a size-dependent behavior...
December 17, 2010: Physical Review Letters
Martin F Melhus, Igor S Aranson, Dmitri Volfson, Lev S Tsimring
The effect of noise on the solid-to-liquid transition of a dense granular assembly under planar shear is studied numerically using soft-particle molecular dynamics simulations in two dimensions. We focus on small systems in a thin planar Couette cell, examining the bistable region while increasing shear, with varying amounts of random noise, and determine statistics of the shear required for fluidization. In the absence of noise, the threshold value of the shear stress depends on the preparation of the system and has a broad distribution...
October 2009: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
Cátia Cardoso Abdo Quintão, Julio Pedra e Cal-Neto, Luciane M Menezes, Carlos Nelson Elias
AIM: This in vitro study measured the force-deflection behavior of selected initial alignment archwires by conducting three-point bending tests under controlled conditions. The study tested four wire designs: multistranded stainless steel, conventional stainless steel, superelastic nickel-titanium, and thermoactivated nickel-titanium archwires. METHOD: The wires (n = 15) were ligated into stainless steel brackets with steel ligatures. A testing machine recorded deactivations at 2...
2009: World Journal of Orthodontics
Jie-Peng Zhang, Xiao-Ming Chen
The porous metal azolate framework [Cu(etz)]infinity (MAF-2, Hetz = 3,5-diethyl-1,2,4-triazole) processes an NbO type cuprous triazolate scaffold and a CsCl type hydrophobic channel system, in which the large cavities are interconnected by small apertures with pendant ethyl groups. Since the ethyl-blocked apertures behave as thermoactivated IRIS stops for the guest molecules, the gas sorption behavior of MAF-2 can be controlled by temperature, in which N2 adsorption was observed at 195 K rather than 77 K. Single-crystal X-ray structural analysis revealed that the [Cu(etz)]infinity host framework is not altered upon N2 inclusion, confirming the occurrence of the so-called " kinetically controlled flexibility"...
May 7, 2008: Journal of the American Chemical Society
Philippe de Diesbach, Thierry Medts, Sarah Carpentier, Ludovic D'Auria, Patrick Van Der Smissen, Anna Platek, Marcel Mettlen, Adrian Caplanusi, Marie-France van den Hove, Donatienne Tyteca, Pierre J Courtoy
Most Src family members are diacylated and constitutively associate with membrane "lipid rafts" that coordinate signalling. Whether the monoacylated Src, frequently hyperactive in carcinomas, also localizes at "rafts" remains controversial. Using polarized MDCK cells expressing the thermosensitive v-Src/tsLA31 variant, we here addressed how Src tyrosine-kinase activation may impact on its (i) membrane recruitment, in particular to "lipid rafts"; (ii) subcellular localization; and (iii) signalling. The kinetics of Src-kinase thermoactivation correlated with its recruitment from the cytosol to sedimentable membranes where Src largely resisted solubilisation by non-ionic detergents at 4 degrees C and floated into sucrose density gradients like caveolin-1 and flotillin-2, i...
April 15, 2008: Experimental Cell Research
Anna Platek, Vassil S Vassilev, Philippe de Diesbach, Donatienne Tyteca, Marcel Mettlen, Pierre J Courtoy
Cancer cells depend on chemotaxis for invasion and frequently overexpress and/or activate Src. We previously reported that v-Src accelerates motility by promoting phosphoinositide 3-kinase (PI3-K) signalling but abrogates chemotaxis. We here addressed the mechanism of the loss of chemotactic response to platelet-derived growth factor (PDGF) gradients in fibroblasts harbouring a thermosensitive v-Src kinase. At non-permissive temperature, PDGF receptor (PDGFR) signalling, assessed by phosphoY(751)-specific antibodies (a docking site for PI3-K), was not detected without PDGF and showed a concentration-dependent PDGF response...
April 1, 2007: Experimental Cell Research
P Kulis, I Tale, G Rudlof
An application of the glow rate technique (GRT) for analysis of the parameters of thermostimulated decay of colour centres is presented using the data on the decay of radiation defects in LiBaF3:Fe crystals created by X rays at 300 K. The GRT offers a procedure for evaluation of the mean activation energy as a function of temperature in the case of arbitrary thermostimulated relaxation kinetics represented by the trap distribution function. The experimental procedure involves at least two subsequent measurements of thermostimulated decay kinetics at different heating rates...
2002: Radiation Protection Dosimetry
Garcia-Palacios, Svedlindh
The nonlinear dynamical response of classical spins governed by the stochastic Landau-Lifshitz equation is found to be large and very sensitive to the damping in the medium-to-weak damping regime. This result is interpreted in terms of a cooperation, induced by the driving field, between the precession of the spin and its thermoactivation over the potential barrier. The large damping dependence (absent in the linear response) can be used to determine the evasive damping coefficient in superparamagnets, so clarifying the nature of the spin-environment interaction in these systems...
October 23, 2000: Physical Review Letters
V M Hyrin, I I Boĭko, V F Rudychenko
Sorption properties were studied of natural and activated specimens of saponite with respect to poliomyelitis virus, Coxsackie B 1 and B 6 viruses as well as to Enterobacteriaceae group bacteria. With the purpose of comparing the processes of sorption of microorganisms, other minerals were also used, such as bentonite, alunite, glauconite, ceolite. The natural saponite adsorptive properties were found out to undergo changes during the process of thermoactivation. Mechanisms are discussed of a decontaminating effect of thermoactivated saponite in water...
January 1999: Likars'ka Sprava
Y Mizuno, P Carninci, Y Okazaki, M Tateno, J Kawai, H Amanuma, M Muramatsu, Y Hayashizaki
We have developed a method for high-efficiency window separation of cDNA display by increasing the specificity of priming in reverse transcription. In the conventional method, two-base anchored oligo(dT) primers (5'dT16VN3', where N is any base and V is G, A or C) are used to make windows for the display of transcripts. However, reverse transcriptase often extends misprimed oligonucleotides. To avoid mispriming from dT16VN primers, we have developed two new technologies. One is higher temperature priming with reverse transcriptase thermoactivated by the disaccharide trehalose...
March 1, 1999: Nucleic Acids Research
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