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Structural Biology
Ocular Cubosome Drug Delivery System for Timolol Maleate: Preparation, Characterization, Cytotoxicity, Ex Vivo, and In Vivo Evaluation
Apr 21, 2017   AAPS PharmSciTech
Huang J, Peng T, Li Y, Zhan Z, Zeng Y, Huang Y, Pan X, Wu CY, Wu C
Ocular Cubosome Drug Delivery System for Timolol Maleate: Preparation, Characterization, Cytotoxicity, Ex Vivo, and In Vivo Evaluation
Apr 21, 2017
AAPS PharmSciTech
Glaucoma is an ocular disease featuring increased intraocular pressure (IOP) and its primary treatment strategy is to lower IOP by medication. Current ocular drug delivery in treating glaucoma is confronting a variety of challenges, such as low corneal permeability and bioavailability due to the unique anatomical structure of the human eye. To tackle these challenges, a cubosome drug delivery system for glaucoma treatment was constructed for timolol maleate (TM) in this study. The TM cubosomes (liquid crystalline nanoparticles) were prepared using glycerol monooleate and poloxamer 407 via high-pressure homogenization. These constructed nanoparticles appeared spherical using transmission electron microscopy and had an average particle size of 142 nm, zeta potential of -6.27 mV, and over 85% encapsulation efficiency. Moreover, using polarized light microscopy and small-angle X-ray scattering (SAXS), it was shown that the TM cubosomes have cubic liquid crystalline D-type (Pn3m) structure, which provides good physicochemical stability and high encapsulation efficiency. Ex vivo corneal permeability experiments showed that the total amount of TM cubosomes penetrated was higher than the commercially available eye drops. In addition, in vivo studies revealed that TM cubosomes reduced the IOP in rabbits from 27.8∼39.7 to 21.4∼32.6 mmHg after 1-week administration and had a longer retention time and better lower-IOP effect than the commercial TM eye drops. Furthermore, neither cytotoxicity nor histological impairment in the rabbit corneas was observed. This study suggests that cubosomes are capable of increasing the corneal permeability and bioavailability of TM and have great potential for ocular disease treatment.
Piecing Together the Allosteric Patterns of Chaperonin GroEL
Apr 21, 2017   The Journal Of Physical Chemistry. B
Chen J, Zhang Q, Ren W, Li W
Piecing Together the Allosteric Patterns of Chaperonin GroEL
Apr 21, 2017
The Journal Of Physical Chemistry. B
Despite considerable effort, elucidating allostery of large macromolecular assemblies at a molecular level in solution remains technically challenging due to its structural complexity. Here we have employed an approach combining amide backbone hydrogen/deuterium exchange coupled with mass spectrometry, fluorescence spectroscopy and molecular simulations to characterize allosteric patterns of chaperonin GroEL, a ~800 kDa tetradecamer from E. coli. Using available crystal structures of GroEL, we quantitatively map out GroEL allosteric changes in solution by resolving exchange behaviors of 133 overlapping proteolytic peptides with more than 95% sequence coverage. This comprehensive analysis gives a refined resolution down to 5 residues to pilot the GroEL allosteric determinants, of which the localized dynamics is monitored by tryptophan-mutated GroEL. Furthermore, the GroEL conformational transition is evaluated by molecular dynamics simulations with an atomic-interaction-based coarse-grained model. Collectively, we provide a practical methodology to analyze GroEL allostery in solution.
Role of the Ion Channel Extracellular Collar in AMPA Receptor Gating
Apr 22, 2017   Scientific Reports
Yelshanskaya MV, Mesbahi-Vasey S, Kurnikova MG, Sobolevsky AI
Role of the Ion Channel Extracellular Collar in AMPA Receptor Gating
Apr 22, 2017
Scientific Reports
AMPA subtype ionotropic glutamate receptors mediate fast excitatory neurotransmission and are implicated in numerous neurological diseases. Ionic currents through AMPA receptor channels can be allosterically regulated via different sites on the receptor protein. We used site-directed mutagenesis and patch-clamp recordings to probe the ion channel extracellular collar, the binding region for noncompetitive allosteric inhibitors. We found position and substitution-dependent effects for introduced mutations at this region on AMPA receptor gating. The results of mutagenesis suggested that the transmembrane domains M1, M3 and M4, which contribute to the ion channel extracellular collar, undergo significant relative displacement during gating. We used molecular dynamics simulations to predict an AMPA receptor open state structure and rationalize the results of mutagenesis. We conclude that the ion channel extracellular collar plays a distinct role in gating and represents a hub for powerful allosteric modulation of AMPA receptor function that can be used for developing novel therapeutics.
Toward a direct and scalable identification of reduced models for categorical processes
Apr 22, 2017   Proceedings Of The National Academy Of Sciences Of The United States Of America
Gerber S, Horenko I
Toward a direct and scalable identification of reduced models for categorical processes
Apr 22, 2017
Proceedings Of The National Academy Of Sciences Of The United States Of America
The applicability of many computational approaches is dwelling on the identification of reduced models defined on a small set of collective variables (colvars). A methodology for scalable probability-preserving identification of reduced models and colvars directly from the data is derived-not relying on the availability of the full relation matrices at any stage of the resulting algorithm, allowing for a robust quantification of reduced model uncertainty and allowing us to impose a priori available physical information. We show two applications of the methodology: (i) to obtain a reduced dynamical model for a polypeptide dynamics in water and (ii) to identify diagnostic rules from a standard breast cancer dataset. For the first example, we show that the obtained reduced dynamical model can reproduce the full statistics of spatial molecular configurations-opening possibilities for a robust dimension and model reduction in molecular dynamics. For the breast cancer data, this methodology identifies a very simple diagnostics rule-free of any tuning parameters and exhibiting the same performance quality as the state of the art machine-learning applications with multiple tuning parameters reported for this problem.
The utility of electron microscopy in detecting asbestos fibers and particles in BALF in diffuse lung diseases
Apr 22, 2017   BMC Pulmonary Medicine
Kido T, Morimoto Y, Yatera K, Ishimoto H, Ogoshi T, Oda K, Yamasaki K, Kawanami T, Shimajiri S, Mukae H
The utility of electron microscopy in detecting asbestos fibers and particles in BALF in diffuse lung diseases
Apr 22, 2017
BMC Pulmonary Medicine
In patients with diffuse lung diseases, differentiating occupational lung diseases from other diseases is clinically important. However, the value of assessing asbestos and particles in bronchoalveolar lavage fluid (BALF) in diffuse lung diseases by electron microscopy (EM) remains unclear. We evaluated the utility of EM in detecting asbestos fibers and particles in patients with diffuse lung diseases. The BALF specimens of 107 patients with diffuse lung diseases were evaluated. First, detection of asbestos by EM and light microscopy (LM) were compared. Second, the detection of asbestos using surgically obtained lung tissues of 8 of 107 patients were compared with the results of EM and LM in BALF. Third, we compared the results of mineralogical components of particles in patients with (n = 48) and without (n = 59) a history of occupational exposure to inorganic dust. BALF asbestos were detected in 11 of 48 patients with a history of occupational exposure by EM; whereas asbestos as asbestos bodies (ABs) were detected in BALF in 4 of these 11 patients by LM. Eight of 107 patients in whom lung tissue samples were surgically obtained, EM detected BALF asbestos at a level of >1,000 fibers/ml in all three patients who had ABs in lung tissue samples by LM at a level of >1,000 fibers/g. The BALF asbestos concentration by EM and in lung tissue by LM were positively correlated. The particle fractions of iron and phosphorus were increased in patients with a history of occupational exposure and both correlated with a history of occupational exposure by a multiple regression analysis. EM using BALF seemed to be superior to LM using BALF and displayed a similar sensitivity to LM using surgically-obtained lung tissue samples in the detection of asbestos. Our results also suggest that detection of elements, such as iron and phosphorus in particles, is useful for evaluating occupational exposure. We conclude that the detection of asbestos and iron and phosphorus in particles in BALF by EM is very useful for the evaluation of occupational exposure.
Direct Growth of Al2O3 on Black Phosphorus by Plasma-Enhanced Atomic Layer Deposition
Apr 22, 2017   Nanoscale Research Letters
Wu BB, Zheng HM, Ding YQ, Liu WJ, Lu HL, Zhou P, Chen L, Sun QQ, Ding SJ, Zhang DW
Direct Growth of Al2O3 on Black Phosphorus by Plasma-Enhanced Atomic Layer Deposition
Apr 22, 2017
Nanoscale Research Letters
Growing high-quality and uniform dielectric on black phosphorus is challenging since it is easy to react with O2 or H2O in ambient. In this work, we have directly grown Al2O3 on BP using plasma-enhanced atomic layer deposition (PEALD). The surface roughness of BP with covered Al2O3 film can reduce significantly, which is due to the removal of oxidized bubble in BP surface by oxygen plasma. It was also found there is an interfacial layer of PO x in between amorphous Al2O3 film and crystallized BP, which is verified by both X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) measurements. By increasing temperature, the PO x can be converted into fully oxidized P2O5.
Cryo-EM Structure of the Open Human Ether-à-go-go-Related K+ Channel hERG
Apr 21, 2017   Cell
Wang W, MacKinnon R
Cryo-EM Structure of the Open Human Ether-à-go-go-Related K+ Channel hERG
Apr 21, 2017
Cell
The human ether-à-go-go-related potassium channel (hERG, Kv11.1) is a voltage-dependent channel known for its role in repolarizing the cardiac action potential. hERG alteration by mutation or pharmacological inhibition produces Long QT syndrome and the lethal cardiac arrhythmia torsade de pointes. We have determined the molecular structure of hERG to 3.8 Å using cryo-electron microscopy. In this structure, the voltage sensors adopt a depolarized conformation, and the pore is open. The central cavity has an atypically small central volume surrounded by four deep hydrophobic pockets, which may explain hERG's unusual sensitivity to many drugs. A subtle structural feature of the hERG selectivity filter might correlate with its fast inactivation rate, which is key to hERG's role in cardiac action potential repolarization. Copyright © 2017 Elsevier Inc. All rights reserved.
Structural and Functional Analysis of a β2-Adrenergic Receptor Complex with GRK5
Apr 21, 2017   Cell
Komolov KE, Du Y, Duc NM, Betz RM, Rodrigues JPGLM, Leib RD, Patra D, Skiniotis G, Adams CM, Dror RO, Chung KY, Kobilka BK, Benovic JL
Structural and Functional Analysis of a β2-Adrenergic Receptor Complex with GRK5
Apr 21, 2017
Cell
The phosphorylation of agonist-occupied G-protein-coupled receptors (GPCRs) by GPCR kinases (GRKs) functions to turn off G-protein signaling and turn on arrestin-mediated signaling. While a structural understanding of GPCR/G-protein and GPCR/arrestin complexes has emerged in recent years, the molecular architecture of a GPCR/GRK complex remains poorly defined. We used a comprehensive integrated approach of cross-linking, hydrogen-deuterium exchange mass spectrometry (MS), electron microscopy, mutagenesis, molecular dynamics simulations, and computational docking to analyze GRK5 interaction with the β2-adrenergic receptor (β2AR). These studies revealed a dynamic mechanism of complex formation that involves large conformational changes in the GRK5 RH/catalytic domain interface upon receptor binding. These changes facilitate contacts between intracellular loops 2 and 3 and the C terminus of the β2AR with the GRK5 RH bundle subdomain, membrane-binding surface, and kinase catalytic cleft, respectively. These studies significantly contribute to our understanding of the mechanism by which GRKs regulate the function of activated GPCRs. PAPERCLIP. Copyright © 2017 Elsevier Inc. All rights reserved.
Phase-Transfer Ligand Exchange of Lead Chalcogenide Quantum Dots for Direct Deposition of Thick, Highly Conductive Films
Apr 21, 2017   Journal Of The American Chemical Society
Lin Q, Yun HJ, Liu W, Song HJ, Makarov NS, Isaienko O, Nakotte T, Chen G, Luo H, Klimov VI, Pietryga JM
Phase-Transfer Ligand Exchange of Lead Chalcogenide Quantum Dots for Direct Deposition of Thick, Highly Conductive Films
Apr 21, 2017
Journal Of The American Chemical Society
The use of semiconductor nanocrystal quantum dots (QDs) in optoelectronic devices typically requires post-synthetic chemical surface treatments to enhance electronic coupling between QDs and allow for efficient charge transport in QD films. Despite their importance to solar cells, and infrared (IR) light-emitting diodes and photodetectors, advances in these chemical treatments for lead chalcogenide (PbE, E = S, Se, Te) QDs have lagged behind those of, for instance, II-VI semiconductor QDs. Here, we introduce a method for fast and effective ligand exchange for PbE QDs in solution, resulting in QDs completely passivated by a wide range of small anionic ligands. Due to electrostatic stabilization, these QDs are readily dispersible in polar solvents, in which they form highly concentrated solutions that remain stable for months. QDs of all three Pb chalcogenides retain their photoluminescence, allowing for a detailed study of the effect of the surface ionic double-layer on electronic passivation of QD surfaces, which we find can be explained using the hard/soft acid-base theory. Importantly, we prepare highly conductive films of PbS, PbSe and PbTe QDs by direct casting from solution without further chemical treatment, as determined by field-effect transistor measurements. This method allows for precise control over the surface chemistry, and therefore the transport properties of deposited films, and allows for the single-step deposition of films of unprecedented thickness via continuous processing techniques, as we demonstrate by preparing a dense, smooth 5.3 µm thick PbSe QD film via doctor blading. As such, it offers important advantages over laborious layer-by-layer methods for solar cells and photodetectors, while opening the door to new possibilities in ionizing radiation detectors.
IFT25, an intraflagellar transporter protein dispensable for ciliogenesis in somatic cells, is essential for sperm flagella formation
Apr 21, 2017   Biology Of Reproduction
Liu H, Li W, Zhang Y, Zhang Z, Shang X,   . . . . . .   , Gerton GL, Foster JA, Hess RA, Pazour GJ, Zhang Z
IFT25, an intraflagellar transporter protein dispensable for ciliogenesis in somatic cells, is essential for sperm flagella formation
Apr 21, 2017
Biology Of Reproduction
Intraflagellar transport (IFT) is a conserved mechanism essential for the assembly and maintenance of most eukaryotic cilia and flagella. However, IFT25, a component of the IFT complex is not required for the formation of cilia in somatic tissues. In mice, the gene is highly expressed in the testis, and its expression is up-regulated during the final phase when sperm flagella are formed. To investigate the role of IFT25 in sperm flagella formation, the gene was specifically disrupted in male germ cells. All homozygous knockout mice survived to adulthood and did not show any gross abnormalities. However, all homozygous knockout males were completely infertile. Sperm numbers were reduced and these sperm were completely immotile. Multiple morphological abnormalities were observed in sperm, including round heads, short and bent tails, with some tails showing branched flagella and others with frequent abnormal thicknesses, as well as swollen tips of the tail. Transmission electron microscopy revealed that flagellar accessory structures, including the fibrous sheath and outer dense fibers, were disorganized, and most sperm had also lost the "9+2" microtubule structure. In the testis, IFT25 forms a complex with other IFT proteins. In Ift25 knockout testes, IFT27, an IFT25 binding partner, was missing, and IFT20 and IFT81 levels were also reduced. Our findings suggest that IFT25, although not necessary for the formation of cilia in somatic cells, is indispensable for sperm flagellum formation and male fertility in mice. © 2017 Society for the Study of Reproduction. Published by Oxford University Press. All rights reserved.
Activation of a c-Jun N-terminal kinase-mediated autophagy pathway attenuates the anticancer activity of gemcitabine in human bladder cancer cells
Apr 21, 2017   Anti-cancer Drugs
Huang XL, Zhang H, Yang XY, Dong XY, Xie XY, Yin HB, Gou X, Lin Y, He WY
Activation of a c-Jun N-terminal kinase-mediated autophagy pathway attenuates the anticancer activity of gemcitabine in human bladder cancer cells
Apr 21, 2017
Anti-cancer Drugs
The role of autophagy in the anticancer activity of gemcitabine (GEM) in bladder cancer is unclear. The aim of this study is to determine whether GEM activates autophagy, the role of autophagy in the anticancer activity of GEM, and the underlying mechanism by which GEM induces autophagy. Human bladder cancer cell lines T24 and BIU87 were treated with GEM in vitro. Cell viability was measured using the Cell Counting Kit-8 assay. Apoptosis was detected by annexin V assay and western blot. Autophagy was measured by western blot and transmission electron microscopy. c-Jun N-terminal kinase (JNK) activation was detected by western blot. Chemical inhibitors were used for intervention of JNK and autophagy. GEM killed bladder cancer cells, which was associated with apoptosis induction. Autophagy was effectively activated by GEM. Suppressing autophagy in GEM-treated cells significantly decreased cell viability, which was associated with increased apoptosis. GEM-induced JNK activation and suppressed B-cell lymphoma 2 expression. The JNK inhibitor SP600125 inhibited GEM-induced autophagy activation and increased GEM's cytotoxicity. GEM kills bladder cancer cells through apoptosis. Meanwhile, JNK-mediated autophagy was activated, which protects the cells against apoptosis. Therefore, inhibition of autophagy could be exploited to enhance the anticancer efficacy of GEM for treating bladder cancer.
Topologically Allowed Nonsixfold Vortices in a Sixfold Multiferroic Material: Observation and Classification
Apr 21, 2017   Physical Review Letters
Cheng S, Li J, Han MG, Deng S, Tan G, Zhang X, Zhu J, Zhu Y
Topologically Allowed Nonsixfold Vortices in a Sixfold Multiferroic Material: Observation and Classification
Apr 21, 2017
Physical Review Letters
We report structural transformation of sixfold vortex domains into two-, four-, and eightfold vortices via a different type of topological defect in hexagonal manganites. Combining high-resolution electron microscopy and Landau-theory-based numerical simulations, we investigate the remarkable atomic arrangement and the intertwined relationship between the vortex structures and the topological defects. The roles of their displacement field, formation temperature, and nucleation sites are revealed. All conceivable vortices in the system are topologically classified using homotopy group theory, and their origins are identified.
A Thorium Chalcogenolate Series Generated by Atom Insertion into Thorium-Carbon Bonds
Apr 21, 2017   Journal Of The American Chemical Society
Settineri NS, Garner ME, Arnold J
A Thorium Chalcogenolate Series Generated by Atom Insertion into Thorium-Carbon Bonds
Apr 21, 2017
Journal Of The American Chemical Society
A new thorium monoalkyl complex, Th(CH2SiMe3)(L3) (L = MeC(NiPr)2) (2), undergoes insertion of chalcogen atoms resulting in a series of thorium chalcogenolate complexes, Th(ECH2SiMe3)(L3) (E = S, SS, Se, Te; 5-8). Complex 6 represents the first alkyl disulfide thorium species and illustrates the ability of 2 to undergo controllable, stoichiometric atom insertion. All complexes have been characterized by 1H and 13C NMR spectroscopy, FTIR, EA, and melting point, and in the case of 1, 2, and 4-8, X-ray crystallography. Insertion was achieved by balancing the thermodynamic driving force of chalcogenolate formation versus the BDE of the pnictogen-chalcogen bond in the transfer reagent. Utilizing Me3NO as an oxygen atom transfer reagent led to C-H activation and SiMe4 extrusion rather than oxygen atom insertion, resulting in the alkoxide complex Th(OCH2NMe2)(L3) (4).
Research on micro-damage behavior of wool fabrics drying in domestic dryer
Apr 21, 2017   Microscopy Research And Technique
Wei Y, Wang X, Su Z, Ding X
Research on micro-damage behavior of wool fabrics drying in domestic dryer
Apr 21, 2017
Microscopy Research And Technique
To evaluate the performance degradation of fabric drying in domestic air-vented dryer, the appearance, mechanical, and microscopic properties of the wool fabric after different drying cycles were studied. Pilling and dimensional stability tests were performed according to established international standards. Microscopic studies were carried out by Scanning Electron Microscopy (SEM) and X-ray (XRD). The results show that pilling is the dominant damage mechanism and gradually increased during lower number of drying cycles (0-10 cycles). The results of dimensional stability showed that the highest dimensional shrinkage of knit wool fabric was first five drying cycles, and then increased at a relatively slow rate with the increase in drying cycles. And fabric shrinkage takes place mainly in the warp direction. The SEM images of wool fiber showed that the scales on the fiber surface were intact in the first 15 drying cycles but start to flake after 20 drying cycles. In the drying process, fabrics can suffer several fractures such as cut fracture, split fracture, partial fracture and distortion and even scale flaking and interior structural distortion of fiber. The damages occur quite randomly, but complexity and severity of damages increased with increase in drying cycles. XRD analysis showed that drying had little effect on fiber crystallinity, indicating that drying only leads to changes in the physical properties of wool fabrics instead of changes in the chemical composition of the fiber. And found SEM analysis is not only an effective method to characterize the change in the surface morphology of the fibers resulting from the drying treatments, but also explain the cause of fabric performance degradation such as pilling and strength reduction during drying. © 2017 Wiley Periodicals, Inc.
Facile synthesis of reduced graphene oxide/Fe3O4 nanocomposite film
Apr 21, 2017   Journal Of Applied Biomaterials & Functional Materials
Ma C, Yang K, Wang L, Wang X
Facile synthesis of reduced graphene oxide/Fe3O4 nanocomposite film
Apr 21, 2017
Journal Of Applied Biomaterials & Functional Materials
This study aims at proposing a facile method to prepare rGO/Fe3O4 composite film with adjusted magnetic properties and electronic conductivity. Colloidal solution of graphene oxide (GO)/Fe3O4 nanoparticles (F-NPs) with a size in the range of 20-80 nm were prepared by a solution-blending method and heated step-by-step from room temperature to 60°C, 120°C and 160°C for 12 hours, respectively, to obtain a reduced graphene oxide (rGO)/F-NP composite film. The structure, morphology, components, magnetic properties and electrical conductivity of the composite films were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, superconducting quantum interference devices and 4-probe instrument. The results indicated that the F-NPs were uniformly distributed on the graphene film, and the composite exhibited good ferromagnetic properties and conductivity, which could be adjusted easily via different loadings of F-NPs. A high content of F-NPs (200 mg) led to a strong saturation magnetization of 63.6 emu·g-1, with a coercivity of about 104.9 oersted (Oe). Whereas a high conductivity of 6.5 S·m-1was obtained at low amounts of F-NPs (40 mg). Notably, rGO/Fe3O4 composite film fabricated by this simple method is widely used in various fields including magnetoelectronics, electrochemical energy conversion and storage, and magnetic nanodevices and others. A graphene-based film deposited by Fe3O4 nanoparticles with controllable loadings has been fabricated by a step-by-step heating treatment of GO/Fe3O4 colloidal solution.
Atomistic non-adiabatic dynamics of the LH2 complex with a GPU-accelerated ab initio exciton model
Apr 21, 2017   Physical Chemistry Chemical Physics : PCCP
Sisto A, Stross C, van der Kamp MW, O'Connor M, McIntosh-Smith S, Johnson GT, Hohenstein EG, Manby FR, Glowacki DR, Martinez TJ
Atomistic non-adiabatic dynamics of the LH2 complex with a GPU-accelerated ab initio exciton model
Apr 21, 2017
Physical Chemistry Chemical Physics : PCCP
We recently outlined an efficient multi-tiered parallel ab initio excitonic framework that utilizes time dependent density functional theory (TDDFT) to calculate ground and excited state energies and gradients of large supramolecular complexes in atomistic detail - enabling us to undertake non-adiabatic simulations which explicitly account for the coupled anharmonic vibrational motion of all the constituent atoms in a supramolecular system. Here we apply that framework to the 27 coupled bacterio-chlorophyll-a chromophores which make up the LH2 complex, using it to compute an on-the-fly nonadiabatic surface-hopping (SH) trajectory of electronically excited LH2. Part one of this article is focussed on calibrating our ab initio exciton Hamiltonian using two key parameters: a shift δ, which corrects for the error in TDDFT vertical excitation energies; and an effective dielectric constant ε, which describes the average screening of the transition-dipole coupling between chromophores. Using snapshots obtained from equilibrium molecular dynamics simulations (MD) of LH2, we tune the values of both δ and ε through fitting to the thermally broadened experimental absorption spectrum, giving a linear absorption spectrum that agrees reasonably well with experiment. In part two of this article, we construct a time-resolved picture of the coupled vibrational and excitation energy transfer (EET) dynamics in the sub-picosecond regime following photo-excitation. Assuming Franck-Condon excitation of a narrow eigenstate band centred at 800 nm, we use surface hopping to follow a single nonadiabatic dynamics trajectory within the full eigenstate manifold. Consistent with experimental data, this trajectory gives timescales for B800→B850 population transfer (τB800→B850) between 650-1050 fs, and B800 population decay (τ800→) between 10-50 fs. The dynamical picture that emerges is one of rapidly fluctuating LH2 eigenstates that are delocalized over multiple chromophores and undergo frequent crossing on a femtosecond timescale as a result of the atomic vibrations of the constituent chromophores. The eigenstate fluctuations arise from disorder that is driven by vibrational dynamics with multiple characteristic timescales. The scalability of our ab initio excitonic computational framework across massively parallel architectures opens up the possibility of addressing a wide range of questions, including how specific dynamical motions impact both the pathways and efficiency of electronic energy-transfer within large supramolecular systems.
One-step fabrication of monolithic electrodes comprising Co9S8 particles supported on cobalt foam for efficient and durable oxygen evolution reaction
Apr 21, 2017   Chemistry (Weinheim An Der Bergstrasse, Germany)
Xiong D, Zhang Q, Thalluri SM, Xu J, Li W, Fu X, Liu L
One-step fabrication of monolithic electrodes comprising Co9S8 particles supported on cobalt foam for efficient and durable oxygen evolution reaction
Apr 21, 2017
Chemistry (Weinheim An Der Bergstrasse, Germany)
We report a very easy and cost-effective approach to the fabrication of monolithic Co9S8 water oxidation electrodes (Co@Co9S8), which is fabricated by one-step hydrothermal treatment of commercially available cobalt foam in the presence of thiourea. The morphology, crystal structure, microstructure, and composition of as-fabricated Co@Co9S8 electrodes are examined using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS), and their electrochemical properties are investigated by cyclic voltammetry (CV), chronopotentiometry (CP), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). When used to catalyze the oxygen evolution reaction (OER) in alkaline solution, the Co@Co9S8 electrode with an optimal Co9S8 loading exhibits outstanding catalytic activity, requiring a low overpotential of 350 mV to deliver an anodic current density of 10 mA cm-2 and showing fast kinetics for OER with a small Tafel slope (55 mV dec-1) and charge transfer resistance (0.44 cm-2), which outperforms many sulfide-based OER catalysts and some state-of-the-art noble metal catalysts recently reported in the literature. Importantly, the electrodes show excellent long-term stability, capable of operating at both a low current density and a high current density relevant to industrial water electrolysis up to 100 hours. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Single-step One-pot Synthesis of TiO2 Nanosheets Doped with Sulfur on Reduced Graphene Oxide with Enhanced Photocatalytic Activity
Apr 21, 2017   Scientific Reports
Wang W, Wang Z, Liu J, Luo Z, Suib SL, He P, Ding G, Zhang Z, Sun L
Single-step One-pot Synthesis of TiO2 Nanosheets Doped with Sulfur on Reduced Graphene Oxide with Enhanced Photocatalytic Activity
Apr 21, 2017
Scientific Reports
A hybrid photocatalyst based on anatase TiO2 was designed by doping TiO2 with sulfur and incorporating reduced graphene oxide (TiO2-S/rGO hybrid), with an aim to narrow the band gap to potentially make use of visible light and decrease the recombination of excitons, respectively. This TiO2-S/rGO hybrid was successfully synthesized using a one-pot hydrothermal method via single-step reaction. The structure and morphology of the TiO2-S/rGO hybrid catalyst was carefully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Its photocatalytic reactivity was evaluated by the degradation of methyl blue. The results showed that both the doping of sulfur and the introduction of rGO worked as designed, and the TiO2-S/rGO hybrid exhibited high photocatalytic activity under simulated sunlight. Considering both the facile and scalable reaction to synthesize TiO2-S/rGO hybrid, and its excellent photocatalytic performance, such TiO2-S/rGO hybrids are expect to find practical applications in environmental and energy sectors.
Noumeavirus replication relies on a transient remote control of the host nucleus
Apr 21, 2017   Nature Communications
Fabre E, Jeudy S, Santini S, Legendre M, Trauchessec M, Couté Y, Claverie JM, Abergel C
Noumeavirus replication relies on a transient remote control of the host nucleus
Apr 21, 2017
Nature Communications
Acanthamoeba are infected by a remarkable diversity of large dsDNA viruses, the infectious cycles of which have been characterized using genomics, transcriptomics and electron microscopy. Given their gene content and the persistence of the host nucleus throughout their infectious cycle, the Marseilleviridae were initially assumed to fully replicate in the cytoplasm. Unexpectedly, we find that their virions do not incorporate the virus-encoded transcription machinery, making their replication nucleus-dependent. However, instead of delivering their DNA to the nucleus, the Marseilleviridae initiate their replication by transiently recruiting the nuclear transcription machinery to their cytoplasmic viral factory. The nucleus recovers its integrity after becoming leaky at an early stage. This work highlights the importance of virion proteomic analyses to complement genome sequencing in the elucidation of the replication scheme and evolution of large dsDNA viruses.
Enhanced photocathodic protection performance of Ag/graphene/TiO2 composite for 304SS under visible light
Apr 21, 2017   Nanotechnology
Li H, Wang X, Wei Q, Liu X, Qian Z, Hou B
Enhanced photocathodic protection performance of Ag/graphene/TiO2 composite for 304SS under visible light
Apr 21, 2017
Nanotechnology
Ag and graphene co-sensitized TiO2 composites were successfully fabricated and used as photoanodes for photogenerated cathodic protection of 304 stainless steel (304SS) under visible light. Graphene films was firstly deposited onto the TiO2 nanotube (NT) films via cyclic voltammetric electrodeposition. Ag/graphene/TiO2 films were then fabricated via dipping and photoreduction method. The morphology, composition and optical response of the Ag/graphene/TiO2 NT composites were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, respectively. The photocathodic protection performance of the Ag/graphene/TiO2 composites were systematically studied through open-circuit potential and potentiodynamic polarization measurements in 3.5 wt% NaCl solution under visible light (λ > 400 nm). The composites exhibited enhanced photogenerated cathodic protection performance for 304SS under visible light irradiation compared to pure TiO2. Graphene and Ag have a synergistic effect on the enhancement of photocathodic protection performance of TiO2. The composites prepared with 30-cycle graphene film and 15 mM AgNO3 solution showed the optimal corrosion protection performance. © 2017 IOP Publishing Ltd.
Thermal Conductivity Enhancement of Coaxial Carbon@Boron Nitride Nanotube Arrays
Apr 21, 2017   ACS Applied Materials & Interfaces
Jing L, Samani MK, Liu B, Li H, Tay RY, Tsang SH, Cometto O, Nylander A, Liu J, Teo EHT, Tok AIY
Thermal Conductivity Enhancement of Coaxial Carbon@Boron Nitride Nanotube Arrays
Apr 21, 2017
ACS Applied Materials & Interfaces
We demonstrate the thermal conductivity enhancement of the vertically aligned carbon nanotube (CNT) arrays (from ~15.5 to 29.5 W/mK, ~90% increase) by encapsulating outer boron nitride nanotube (BNNT, 0.97 nm-thick with ~3-4 walls). The heat transfer enhancement mechanism of the coaxial C@BNNT was further revealed by molecular dynamics simulations. Owing to their highly coherent lattice structures, the outer BNNT serves as additional heat conducting path without impairing the thermal conductance of inner CNT. This work provides deep insights into tailoring the heat transfer of arbitrary CNT arrays and will enable their broader applications as thermal interface material.
Recovery from Talaromyces marneffei involving the kidney in a renal transplant recipient: A case report and literature review
Apr 21, 2017   Transplant Infectious Disease : An Official Journal Of The Transplantation Society
Peng J, Chen Z, Cai R, Huang X, Lin L, Liang W, Xiong Z, Chen J, Chen H, Yang Y, Liu S, Jiang Q
Recovery from Talaromyces marneffei involving the kidney in a renal transplant recipient: A case report and literature review
Apr 21, 2017
Transplant Infectious Disease : An Official Journal Of The Transplantation Society
Talaromyces marneffei is an emerging opportunistic infection among immunocompromised patients. We observe the first native case of disseminated T. marneffei involving the kidney in a renal transplant recipient in mainland China. We describe the comprehensive clinical course, and ultrasound imaging of renal transplant biopsy, pathologic images, and electron microscopy observation of the biopsy specimen, highlighting the relevance of biopsy findings and the blood culture. We also focus on the treatment and good outcome of the patient. Then we review the literature and show the additional 10 reported cases of T. marneffei in renal transplant recipients. In addition, we discuss the new methods of rapid diagnosis of T. marneffei. In brief, timely diagnosis and proper treatment of T. marneffei infection is important in renal transplant recipient. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
The Dynamics of the Reaction of FeO+ and H2 : A Model for Inorganic Oxidation
Apr 21, 2017   Angewandte Chemie (International Ed. In English)
Essafi S, Tew DP, Harvey JN
The Dynamics of the Reaction of FeO+ and H2 : A Model for Inorganic Oxidation
Apr 21, 2017
Angewandte Chemie (International Ed. In English)
Extensive density functional theory (DFT) calculations using the B3LYP functional were used to explore the sextet and quartet energy potential energy surfaces (PESs) of the title reaction, and as a basis to fit global analytical reactive PESs. Surface-hopping dynamics on these PESs reproduce the experimentally observed reactivity and confirm that hydrogen activation rather than spin-state change is rate-limiting at low reaction energy, where the main products are Fe+ and H2 O. A change in spin state is inefficient in the product region so that excited-state 4 Fe+ is the dominant product. At higher energies, spin-allowed hydrogen atom abstraction to form FeOH+ predominates. At intermediate energy, a previously unexpected rebound mechanism contributes significantly to the reactivity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Nanodiscs for INPHARMA NMR Characterization of GPCRs: Ligand Binding to the Human A2A Adenosine Receptor
Apr 21, 2017   Angewandte Chemie (International Ed. In English)
Fredriksson K, Lottmann P, Hinz S, Onila I, Shymanets A, Harteneck C, Müller CE, Griesinger C, Exner TE
Nanodiscs for INPHARMA NMR Characterization of GPCRs: Ligand Binding to the Human A2A Adenosine Receptor
Apr 21, 2017
Angewandte Chemie (International Ed. In English)
G-protein-coupled-receptors (GPCRs) are of fundamental importance for signal transduction through cell membranes. This makes them important drug targets, but structure-based drug design (SBDD) is still hampered by the limitations for structure determination of unmodified GPCRs. We show that the interligand NOEs for pharmacophore mapping (INPHARMA) method can provide valuable information on ligand poses inside the binding site of the unmodified human A2A adenosine receptor reconstituted in nanodiscs. By comparing experimental INPHARMA spectra with back-calculated spectra based on ligand poses obtained from molecular dynamics simulations, a complex structure for A2A R with the low-affinity ligand 3-pyrrolidin-1-ylquinoxalin-2-amine was determined based on the X-ray structure of ligand ZM-241,358 in complex with a modified A2A R. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Probing protein flexibility reveals a mechanism for selective promiscuity
Apr 22, 2017   ELife
Pabon NA, Camacho CJ
Probing protein flexibility reveals a mechanism for selective promiscuity
Apr 22, 2017
ELife
Many eukaryotic regulatory proteins adopt distinct bound and unbound conformations, and use this structural flexibility to bind specifically to multiple partners. However, we lack an understanding of how an interface can select some ligands, but not others. Here, we present a molecular dynamics approach to identify and quantitatively evaluate the interactions responsible for this selective promiscuity. We apply this approach to the anti-cancer target PD-1 and its ligands PD-L1 and PD-L2. We discover that while unbound PD-1 exhibits a hard-to-drug hydrophilic interface, conserved specific triggers encoded in the cognate ligands activate a promiscuous binding pathway that reveals a flexible hydrophobic binding cavity. Specificity is then established by additional contacts that stabilize the PD-1 cavity into distinct bound-like modes. Collectively, our studies provide insight into the structural basis and evolution of multiple binding partners, and also suggest a biophysical approach to exploit innate binding pathways to drug seemingly undruggable targets.

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