bluuebunny/crossref_metadata_2025 huggingface dataset:
Layer specific and general requirements for ERK/MAPK signaling in the developing neocortex
Authors: Xing Lei , Larsen Rylan S , Bjorklund George Reed , Li Xiaoyan , Wu Yaohong , Philpot Benjamin D , Snider William D , Newbern Jason M
Published: February 2016

Aberrant signaling through the Raf/MEK/ERK (ERK/MAPK) pathway causes pathology in a family of neurodevelopmental disorders known as 'RASopathies' and is implicated in autism pathogenesis. Here, we have determined the functions of ERK/MAPK signaling in developing neocortical excitatory neurons. Our data reveal a critical requirement for ERK/MAPK signaling in the morphological development and survival of large Ctip2+ neurons in layer 5. Loss of Map2k1/2 (Mek1/2) led to deficits in corticospinal tract formation and subsequent corticospinal neuron apoptosis. ERK/MAPK hyperactivation also led to reduced corticospinal axon elongation, but was associated with enhanced arborization. ERK/MAPK signaling was dispensable for axonal outgrowth of layer 2/3 callosal neurons. However, Map2k1/2 deletion led to reduced expression of Arc and enhanced intrinsic excitability in both layers 2/3 and 5, in addition to imbalanced synaptic excitation and inhibition. These data demonstrate selective requirements for ERK/MAPK signaling in layer 5 circuit development and general effects on cortical pyramidal neuron excitability.
Efficient red, green, blue and white organic light-emitting diodes with same exciplex host
Authors: Chang Chih-Hao , Wu Szu-Wei , Huang Chih-Wei , Hsieh Chung-Tsung , Lin Sung-En , Chen Nien-Po , Chang Hsin-Hua
Published: February 2016

Recently, exciplex had drawn attention because of its potential for efficient electroluminescence or for use as a host in organic light-emitting diodes (OLEDs). In this study, four kinds of hole transport material/electron transport material combinations were examined to verify the formation of exciplex and the corresponding energy bandgaps. We successfully demonstrated that the combination of tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and 3,5,3′,5′-tetra(m-pyrid-3-yl)phenyl[1,1′]biphenyl (BP4mPy) could form a stable exciplex emission with an adequate energy gap. Using exciplex as a host in red, green, and blue phosphorescent OLEDs with an identical trilayer architecture enabled effective energy transfer from exciplex to emitters, achieving corresponding efficiencies of 8.8, 14.1, and 15.8%. A maximum efficiency of 11.3% and stable emission was obtained in white OLEDs.
Optimal conditions for decorating outer surface of single-walled carbon nanotubes with RecA proteins
Authors: Oura Shusuke , Umemura Kazuo
Published: February 2016

In this study, we estimated the optimal reaction conditions for decorating the outer surface of single-walled carbon nanotubes (SWNTs) with RecA proteins by comparison with hybrids of RecA and single-stranded DNA (ssDNA). To react SWNTs with RecA proteins, we first prepared ssDNA–SWNT hybrids. The heights of the ssDNA–SWNT hybrids increased as the amount of RecA used in the reaction increased, as determined from atomic force microscopy images. We further confirmed the increasing adsorption of RecA proteins onto ssDNA on SWNT surfaces by agarose gel electrophoresis. These results suggest that the combination of RecA proteins and ssDNA–SWNT hybrids forms RecA–ssDNA–SWNT hybrids. We also successfully controlled the amount of RecA adsorbed on the ssDNA–SWNT hybrids. Our results thus indicate the optimized reaction conditions for decorating the outer surface of SWNTs with RecA proteins, which is the key to the development of novel biosensors and nanomaterial-based bioelectronics.
Imaging the midlatitude sporadic E plasma patches with a coordinated observation of spaceborne InSAR and GPS total electron content
Authors: Maeda Jun , Suzuki Takato , Furuya Masato , Heki Kosuke
Published: February 2016

Kilometer‐scale fine structures of midlatitude sporadic E (Es) plasma patches have been directly imaged for the first time by an interferogram derived from L band Advanced Land Observation Satellite/Phased Array‐type L band Synthetic Aperture Radar data obtained over southwestern Japan. The synthetic aperture radar interferogram captured the eastern part of a large‐scale frontal structure of daytime midlatitude Es which spans over 250 km in the east‐northeast to west‐southwest direction. Fine structures are characterized by frontal and disc‐shaped patches which are elongated in the same direction as the large‐scale frontal structure. Length and width of the disc‐shaped patches are 10–20 km and 5–10 km, respectively, and they are quasi‐periodically located with a typical separation of 10–15 km. The Kelvin‐Helmholtz instability with the vertical shear of zonal winds is considered to be the most likely candidate for the generation mechanism of the frontal patch and disc‐shaped patches aligned in the zonal direction.
Numerical simulation of multiple CME‐driven shocks in the month of 2011 September
Authors: Wu Chin‐Chun , Liou Kan , Vourlidas Angelos , Plunkett Simon , Dryer Murray , Wu S. T. , Socker Dennis , Wood Brian E. , Hutting Lynn , Howard Russell A.
Published: February 2016

A global, three‐dimensional (3‐D) numerical simulation model has been employed to study the Sun‐to‐Earth propagation of multiple (12) coronal mass ejections (CMEs) and their associated shocks in September 2011. The inputs to the simulation are based on actual solar observations, which include the CME speeds, source locations, and photospheric magnetic fields. The simulation result is fine tuned with in situ solar wind data observations at 1 AU by matching the arrival time of CME‐driven shocks. During this period three CME‐driven interplanetary (IP) shocks induced three sizable geomagnetic storms on 9, 17, and 26 September, with Dst values reaching −69, −70, and −101 nT, respectively. These storm events signify the commencement of geomagnetic activity in the solar cycle 24. The CME propagation speed near the Sun (e.g., < 30 RS) has been widely used to estimate the interplanetary CME (ICME)/Shock arrival time at 1 AU. Our simulation indicates that the background solar wind speed, as expected, is an important controlling parameter in the propagation of IP shocks and CMEs. Prediction of the ICME/shock arrival time at 1 AU can be more problematic for slow (e.g., < 500 km s−1) than fast CMEs (>1000 km s−1). This is because the effect of the background solar wind is more pronounced for slow CMEs. Here we demonstrate this difficulty with a slow (400 km s−1) CME event that arrived at the Earth in 3 days instead of the predicted 4.3 days. Our results also demonstrate that a long period (a month in this case) of simulation may be necessary to make meaningful solar source geomagnetic storm associations.
Upper mantle structure of central and West Antarctica from array analysis of Rayleigh wave phase velocities
Authors: Heeszel David S. , Wiens Douglas A. , Anandakrishnan Sridhar , Aster Richard C. , Dalziel Ian W. D. , Huerta Audrey D. , Nyblade Andrew A. , Wilson Terry J. , Winberry J. Paul
Published: February 2016

The seismic velocity structure of Antarctica is important, both as a constraint on the tectonic history of the continent and for understanding solid Earth interactions with the ice sheet. We use Rayleigh wave array analysis methods applied to teleseismic data from recent temporary broadband seismograph deployments to image the upper mantle structure of central and West Antarctica. Phase velocity maps are determined using a two–plane wave tomography method and are inverted for shear velocity using a Monte Carlo approach to estimate three‐dimensional velocity structure. Results illuminate the structural dichotomy between the East Antarctic Craton and West Antarctica, with West Antarctica showing thinner crust and slower upper mantle velocity. West Antarctica is characterized by a 70–100 km thick lithosphere, underlain by a low‐velocity zone to depths of at least 200 km. The slowest anomalies are beneath Ross Island and the Marie Byrd Land dome and are interpreted as upper mantle thermal anomalies possibly due to mantle plumes. The central Transantarctic Mountains are marked by an uppermost mantle slow‐velocity anomaly, suggesting that the topography is thermally supported. The presence of thin, higher‐velocity lithosphere to depths of about 70 km beneath the West Antarctic Rift System limits estimates of the regionally averaged heat flow to less than 90 mW/m2. The Ellsworth‐Whitmore block is underlain by mantle with velocities that are intermediate between those of the West Antarctic Rift System and the East Antarctic Craton. We interpret this province as Precambrian continental lithosphere that has been altered by Phanerozoic tectonic and magmatic activity.
Three‐dimensional seismic velocity structure in the Sichuan basin, China
Authors: Wang Maomao , Hubbard Judith , Plesch Andreas , Shaw John H. , Wang Lining
Published: February 2016

We present a new three‐dimensional velocity model of the crust in the eastern margin of the Tibetan Plateau. The model describes the velocity structure of the Sichuan basin and surrounding thrust belts. The model consists of 3‐D surfaces representing major geologic unit contacts and faults and is parameterized with Vp velocity‐depth functions calibrated using sonic logs. The model incorporates data from 1166 oil wells, industry isopach maps, geological maps, and a digital elevation model. The geological surfaces were modeled based on structure contour maps for various units from oil wells and seismic reflection profiles. These surfaces include base Quaternary, Mesozoic, Paleozoic, and Proterozoic horizons. The horizons locally exhibit major offsets that are compatible with the locations and displacements of important faults systems. This layered, upper crustal 3‐D model extends down to 10–15 km depth and illustrates lateral and vertical variations of velocity that reflect the complex evolution of tectonics and sedimentation in the basin. The model also incorporates 3‐D descriptions of Vs and density for sediments that are obtained from empirical relationships with Vp using direct measurements of these properties in borehole logs. To illustrate the impact of our basin model on earthquake hazards assessment, we use it to calculate ground motions and compare these with observations for the 2013 Lushan earthquake. The result demonstrates the effects of basin amplification in the western Sichuan basin. The Sichuan CVM model is intended to facilitate fault systems analysis, strong ground motion prediction, and earthquake hazards assessment for the densely populated Sichuan region.
Rapid identification of transience in streambed conductance by inversion of floodwave responses
Authors: Gianni Guillaume , Richon Julien , Perrochet Pierre , Vogel Alexandre , Brunner Philip
Published: February 2016

Streambed conductance controls the interaction between surface and groundwater. However, the streambed conductance is often subject to transience. Directly measuring hydraulic properties in a river yields only point values, is time‐consuming and therefore not suited to detect transience of physical properties. Here, we present a method to continuously monitor transience in streambed conductance. Input data are time series of stream stage and near stream hydraulic head. The method is based on the inversion of floodwave responses. The analytical model consists of three parameters: x, the distance between streambank and an observation well, α, the aquifer diffusivity, and a the retardation coefficient that is inversely proportional to the streambed conductance. Estimation of a is carried out over successive time steps in order to identify transience in streambed conductance. The method is tested using synthetic data and is applied to field data from the Rhône River and its alluvial aquifer (Switzerland). The synthetic method demonstrated the robustness of the proposed methodology. Application of the method to the field data allowed identifying transience in streambed properties, following flood events in the Rhône. This method requires transience in the surface water, and the river should not change its width significantly with a rising water level. If these conditions are fulfilled, this method allows for a rapid and effective identification of transience in streambed conductance.
Persistence and memory timescales in root‐zone soil moisture dynamics
Authors: Ghannam Khaled , Nakai Taro , Paschalis Athanasios , Oishi Christopher A. , Kotani Ayumi , Igarashi Yasunori , Kumagai Tomo'omi , Katul Gabriel G.
Published: February 2016

The memory timescale that characterizes root‐zone soil moisture remains the dominant measure in seasonal forecasts of land‐climate interactions. This memory is a quasi‐deterministic timescale associated with the losses (e.g., evapotranspiration) from the soil column and is often interpreted as persistence in soil moisture states. Persistence, however, represents a distribution of time periods where soil moisture resides above or below some prescribed threshold and is therefore inherently probabilistic. Using multiple soil moisture data sets collected at high resolution (subhourly) across different biomes and climates, this paper explores the differences, underlying dynamics, and relative importance of memory and persistence timescales in root‐zone soil moisture. A first‐order Markov process, commonly used to interpret soil moisture fluctuations derived from climate simulations, is also used as a reference model. Persistence durations of soil moisture below the plant water‐stress level (chosen as the threshold), and the temporal spectrum of upcrossings and downcrossings of this threshold, are compared to the memory timescale and spectrum of the full time series, respectively. The results indicate that despite the differences between meteorological drivers, the spectrum of threshold‐crossings is similar across sites, and follows a unique relation with that of the full soil moisture series. The distribution of persistence times exhibits an approximate stretched exponential type and reflects a likelihood of exceeding the memory at all sites. However, the rainfall counterpart of these distributions shows that persistence of dry atmospheric periods is less likely at sites with long soil moisture memory. The cluster exponent, a measure of the density of threshold‐crossings in a time frame, reveals that the clustering tendency in rainfall events (on‐off switches) does not translate directly to clustering in soil moisture. This is particularly the case in climates where rainfall and evapotranspiration are out of phase, resulting in less ordered (more independent) persistence in soil moisture than in rainfall.
Watershed memory at the Coweeta Hydrologic Laboratory: The effect of past precipitation and storage on hydrologic response
Authors: Nippgen Fabian , McGlynn Brian L. , Emanuel Ryan E. , Vose James M.
Published: February 2016

The rainfall‐runoff response of watersheds is affected by the legacy of past hydroclimatic conditions. We examined how variability in precipitation affected streamflow using 21 years of daily streamflow and precipitation data from five watersheds at the Coweeta Hydrologic Laboratory in southwestern North Carolina, USA. The gauged watersheds contained both coniferous and deciduous vegetation, dominant north and south aspects, and differing precipitation magnitudes. Lag‐correlations between precipitation and runoff ratios across a range of temporal resolutions indicated strong influence of past precipitation (i.e., watershed memory). At all time‐scales, runoff ratios strongly depended on the precipitation of previous time steps. At monthly time scales, the influence of past precipitation was detectable for up to 7 months. At seasonal time scales, the previous season had a greater effect on a season's runoff ratio than the same season's precipitation. At annual time scales, the previous year was equally important for a year's runoff ratio than the same year's precipitation. Estimated watershed storage through time and specifically the previous year's storage state was strongly correlated with the residuals of a regression between annual precipitation and annual runoff, partially explaining observed variability in annual runoff in watersheds with deep soils. This effect was less pronounced in the steepest watershed that also contained shallow soils. We suggest that the location of a watershed on a nonlinear watershed‐scale storage‐release curve can explain differences in runoff during growing and dormant season between watersheds with different annual evapotranspiration.
Magnetic Nanoparticle Facilitated Drug Delivery for Cancer Therapy with Targeted and Image‐Guided Approaches
Authors: Huang Jing , Li Yuancheng , Orza Anamaria , Lu Qiong , Guo Peng , Wang Liya , Yang Lily , Mao Hui
Published: February 2016

With rapid advances in nanomedicine, magnetic nanoparticles (MNPs) have emerged as a promising theranostic tool in biomedical applications, including diagnostic imaging, drug delivery and novel therapeutics. Significant preclinical and clinical research has explored their functionalization, targeted delivery, controllable drug release and image‐guided capabilities. To further develop MNPs for theranostic applications and clinical translation in the future, we attempt to provide an overview of the recent advances in the development and application of MNPs for drug delivery, specifically focusing on the topics concerning the importance of biomarker targeting for personalized therapy and the unique magnetic and contrast‐enhancing properties of theranostic MNPs that enable image‐guided delivery. The common strategies and considerations to produce theranostic MNPs and incorporate payload drugs into MNP carriers are described. The notable examples are presented to demonstrate the advantages of MNPs in specific targeting and delivering under image guidance. Furthermore, current understanding of delivery mechanisms and challenges to achieve efficient therapeutic efficacy or diagnostic capability using MNP‐based nanomedicine are discussed.
Nanoparticle‐Based Antivirulence Vaccine for the Management of Methicillin‐Resistant Staphylococcus aureus Skin Infection
Authors: Wang Fei , Fang Ronnie H. , Luk Brian T. , Hu Che‐Ming J. , Thamphiwatana Soracha , Dehaini Diana , Angsantikul Pavimol , Kroll Ashley V. , Pang Zhiqing , Gao Weiwei , Lu Weiyue , Zhang Liangfang
Published: February 2016

With the rising threat of antibiotic‐resistant bacteria, vaccination is becoming an increasingly important strategy to prevent and manage bacterial infections. Made from deactivated bacterial toxins, toxoid vaccines are widely used in the clinic as they help to combat the virulence mechanisms employed by different pathogens. Here, the efficacy of a biomimetic nanoparticle‐based antivirulence vaccine is examined in a mouse model of methicillin‐resistant Staphylococcus aureus (MRSA) skin infection. Vaccination with nanoparticle‐detained staphylococcal α‐hemolysin (Hla) effectively triggers the formation of germinal centers and induces high anti‐Hla titers. Compared to mice vaccinated with control samples, those vaccinated with the nanoparticle toxoid show superior protective immunity against MRSA skin infection. The vaccination not only inhibits lesion formation at the site of bacterial challenge but also reduces the invasiveness of MRSA, preventing dissemination into other organs. Overall, this biomimetic nanoparticle‐based toxin detainment strategy is a promising method for the design of potent antivirulence vaccines for managing bacterial infections.
Synthesis, Characterization, and Antibacterial Activity of New Poly(ether‐amide)/Silver Nanocomposites
Authors: Faghihi Khalil , Raeisi Ahmad , Honardoost Elham , Shabanian Meisam , Mirzakhanian Zeinab
Published: February 2016

In this work, a series of antibacterial poly(ether‐amide)/silver nanocomposites (PANCs) was prepared via in situ preparation of Ag nanoparticles within a new poly(ether‐amide) (PA) matrix. A new type of dicarboxylic acid (DA) containing ether and aliphatic moieties was successfully synthesized via a solvent‐free reaction. Then a new PA with high solubility in common organic solvents was synthesized from a direct reaction of 4,4‐diamino diphenylmethane and the DA. Silver nanoparticles were embedded within the PA chains through using a silver/ammonia complex [Ag(NH3)2]+. The formation of nano silver was confirmed by X‐ray diffraction, transmission electron microscopy, and UV–vis spectroscopy. The effect of Ag nanoparticles on thermal properties of the prepared nanocomposites was studied by the thermogravimetric analysis. The results showed that the thermal properties of the nanocomposites were improved as compared with the neat PA. The antibacterial capability of the PANCs was studied by the disk diffusion method against Escherichia coli, which suggested that the PANCs can be considered as good antibacterial agents.
Sandwiched Composite Fluorocarbon Film for Flexible Electret Generator
Authors: Wang Bo , Zhong Junwen , Zhong Qize , Wu Nan , Cheng Xiaofeng , Li Wenbo , Liu Kang , Huang Liang , Hu Bin , Zhou Jun
Published: February 2016

An electret material with high charge storage ability is the key factor for fabricating high performance electret generator for wearable electronics and self‐powered sensor systems. This work presents a new sandwiched composite fluorocarbon (SCF) film, which stores more residual charges compared to traditional electret materials such as dense fluorinated ethylene propylene or fibrous polytetrafluoroethylene films with the same thickness. Electret generator based on the SCF film shows a largest peak power density of ≈31.4 μW cm−2 with load resistance of 40 MΩ. Moreover, the application of the electret generator for a self‐powered human breathing sensor is also demonstrated. This work offers a new strategy to enhance the output of the electret generators.
Chemo‐, Diastereo‐, and Enantioselective Iridium‐Catalyzed Allylic Intramolecular Dearomatization Reaction of Naphthol Derivatives
Authors: Cheng Qiang , Wang Ye , You Shu‐Li
Published: February 2016

An iridium‐catalyzed intramolecular asymmetric allylic dearomatization reaction of naphthol derivatives is described. Challenges confronted in this reaction include chemoselectivity between carbon and oxygen atoms as nucleophilic centers, diastereoselectivity when contiguous chiral centers are generated, and enantioselective control for constructing an all‐carbon quaternary stereocenter. In the presence of an iridium catalyst generated from [{Ir(dbcot)Cl}2] (dbcot=dibenzocyclooctatetraene) and a new THQphos (tetrahydroquinolinedinaphthophosphoramidite) ligand, various spironaphthalenones were obtained with up to greater than 95:5 C/O selectivity, greater than 95:5 d.r., and 99 % ee, thus providing a general method for the dearomatization of naphthols.
Asymmetrische Hydrierung von Vinylthioethern: Zugang zu optisch aktiven 1,5‐Benzothiazepinderivaten
Authors: Li Wei , Schlepphorst Christoph , Daniliuc Constantin , Glorius Frank
Published: February 2016

Eine neuartige asymmetrische Hydrierung von Vinylthioethern unter Verwendung eines Ruthenium(II)‐NHC‐Komplexes ermöglicht die effiziente Herstellung optisch aktiver 1,5‐Benzothiazepine mit C‐S‐Bindungen am Stereozentrum. Exzellente Enantioselektivitäten (bis zu 95 % ee) und hohe Ausbeuten (bis zu 99 %) wurden für eine Vielzahl von Substraten mit nützlichen funktionellen Gruppen erhalten. Außerdem konnte diese Methode bei der Synthese des Antidepressivums R‐(−)‐Thiazesim angewendet werden.
Quercetin 2,4‐Dioxygenase Activates Dioxygen in a Side‐On O2–Ni Complex
Authors: Jeoung Jae‐Hun , Nianios Dimitrios , Fetzner Susanne , Dobbek Holger
Published: February 2016

Quercetin 2,4‐dioxygenase (quercetinase) from Streptomyces uses nickel as the active‐site cofactor to catalyze oxidative cleavage of the flavonol quercetin. How this unusual active‐site metal supports catalysis and O2 activation is under debate. We present crystal structures of Ni‐quercetinase in three different states, thus providing direct insight into how quercetin and O2 are activated at the Ni2+ ion. The Ni2+ ion is coordinated by three histidine residues and a glutamate residue (E76) in all three states. Upon binding, quercetin replaces one water ligand at Ni and is stabilized by a short hydrogen bond through E76, the carboxylate group of which rotates by 90°. This conformational change weakens the interaction between Ni and the remaining water ligand, thereby preparing a coordination site at Ni to bind O2. O2 binds side‐on to the Ni2+ ion and is perpendicular to the C2−C3 and C3−C4 bonds of quercetin, which are cleaved in the following reaction steps.
Atom‐Precise Organometallic Zinc Clusters
Authors: Banh Hung , Dilchert Katharina , Schulz Christine , Gemel Christian , Seidel Rüdiger W. , Gautier Régis , Kahlal Samia , Saillard Jean‐Yves , Fischer Roland A.
Published: February 2016

The bottom‐up synthesis of organometallic zinc clusters is described. The cation {[Zn10](Cp*)6Me}+ (1) is obtained by reacting [Zn2Cp*2] with [FeCp2][BAr4F] in the presence of ZnMe2. In the presence of suitable ligands, the high reactivity of 1 enables the controlled abstraction of single Zn units, providing access to the lower‐nuclearity clusters {[Zn9](Cp*)6} (2) and {[Zn8](Cp*)5(tBuNC)3}+ (3). According to DFT calculations, 1 and 2 can be described as closed‐shell species that are electron‐deficient in terms of the Wade–Mingos rules because the apical ZnCp* units that constitute the cluster cage do not have three, but only one, frontier orbitals available for cluster bonding. Zinc behaves flexibly in building the skeletal metal–metal bonds, sometimes providing one major frontier orbital (like Group 11 metals) and sometimes providing three frontier orbitals (like Group 13 elements).
Tribological behaviors of carbon series additions reinforced CF/PTFE composites at high speed
Authors: Ye Pengpeng , Wu Jian , Mu Liwen , He Dafang , Feng Xin , Lu Xiaohua
Published: February 2016

The tribological, mechanical, and thermal properties of carbon series additions reinforced CF/PTFE composites at high speed were investigated. In this work, carbon fiber (CF) filled polytetrafluoroethylene (PTFE) composites, which have excellent tribological properties under normal sliding speed (1.4 m/s), were filled with some carbon materials [graphene (GE), carbon nanotubes (CNTs) and graphite (Gr)] respectively to investigate the tribological properties of CF/PTFE composites at high sliding speed (2.1 and 2.5 m/s). The results reveal that the carbon series additions can improve the friction and anti‐wear performances of CF/PTFE, and GE is the most effective filler. The wear rate of 0.8 wt % GE/CF/PTFE was decreased by 50 − 55%, 55 − 60%, 40 − 45% at 1.4, 2.1, and 2.5 m/s compared with CF/PTFE. SEM study shows GE could be helpful to form smooth and continuous transfer film on the surface of counterparts. Meanwhile, GE can improve its tensile strength and elastic modulus obviously. Thin layer structure of GE could enhance the thermal conductivity, which can be helpful to dissipate heat of CF/PTFE composites wear surface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43236.
Acid catalyst influence on the polymerization time of polyfurfuryl alcohol and on the porosity of monolithic vitreous carbon
Authors: Origo Fábio Dondeo , Arisseto Júlia Cassiano , Seixas Fernanda Lini , Miyakawa Walter , Damião Alvaro José , Oishi Sílvia Sizuka , Botelho Edson Cocchieri
Published: February 2016

This study compares the influence of different acid catalysts on the polymerization rate of polyfurfuryl alcohol (PFA) precursor and especially on the respective porosity of Monolithic Vitreous Carbon (MVC) produced from that. Five acid catalysts commonly used were compared: p‐toluenesulfonic (PTLS), hydrochloric, sulfuric, nitric, and phosphoric. A fixed molar concentration of catalyst was diluted in PFA resin under room pressure and temperature. The time dependence of PFA resin polymerization was investigated by optical transmittance of PFA films, and the polymerization degree, characterized by ATR spectroscopy and thermogravimetry. MVC samples prepared with the same PFA resin and each catalyst were carbonized up to 1200 °C, under inert atmosphere. MVC porosity was studied by nitrogen adsorption/desorption, and by SEM and optical microscopy. Higher polymerization degree and higher residual mass were obtained with faster catalysts. No direct relation between the polymerization rate and the acid force was observed. PTLS promoted the fastest PFA polymerization process and the sulfuric acid, the slowest one. MVC samples were obtained by slow carbonization. MVC presented low specific surface SBET from 1.4 to 7.4 m2/g. Nitric acid catalyst contributed the most to micropores formation. Micrometric apparent porosity was smaller for the catalysts having longer polymerizations times, such as phosphoric and sulfuric acid. Phosphoric catalyst corresponded to the lowest porosity in MVC. As the polymerization time increased, the average size of the micrometric surface pores tended to augment. The MVC macroscopic porosity increased with the SBET increment. Acid catalysts choice exerted a fundamental role on the porosity of MVC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43272.
Comparison of the effects of linking diglycidyl ether‐terminated PDMS and BPA onto polyurethane with respect to the tensile and thermal properties
Authors: Chung Yong‐Chan , Chung Kyung Hoon , Lee Byung Hee , Chun Byoung Chul
Published: February 2016

Flexible poly(dimethylsiloxane) (PDMS) or rigid bisphenol A (BPA) with diglycidyl ether end groups was linked to polyurethane (PU), which was composed of 4,4′‐methylenebis(phenyl isocyanate) as a hard segment and poly(tetramethylene ether)glycol as a soft segment. A control PDMS (CPDMS) series was prepared with an additional deprotonation step by NaH. The spectroscopic, thermal, tensile, shape memory, and low‐temperature flexibility properties were compared with those of plain PU to investigate the effects of linking the flexible PDMS or the rigid BPA on PU. The soft segment melting peaks were not affected by the PDMS content for the PDMS series but disappeared as the BPA content increased in the BPA series. The soft segment crystallization of PU was completely disrupted as the linked BPA content increased in the differential scanning calorimetry results and disappeared in the dynamic mechanical analysis results. The glass transition temperature (Tg) of the BPA series increased with increasing BPA content, whereas that of the PDMS series remained the same. The tensile strength of the PDMS series sharply increased with increasing PDMS content. The shape retention of the BPA series at −25 °C sharply decreased as the BPA content increased. Finally, the BPA series linked with rigid aromatic BPA demonstrated excellent low‐temperature flexibilities compared with the PDMS series and plain PU. Compared with PUs linked with PDMS, PUs linked with rigid BPA demonstrated a significant change in the cross‐link density, thermal properties, shape retention, and low‐temperature flexibility. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43284.
Preparation of acrylate copolymer modified byTiO2nanoparticles with excellent photo‐oxidative stability for application in ancient ivory conservation
Authors: Zhang Wenqing , Zhang Yulong , Fang Shuying , Luo Xiyun , Jin Haiyang , Xu Zhizhen , Xia Wei
Published: February 2016

In this work, acrylate copolymer has been fabricated by graft copolymerization of acrylate monomer (EMA:EA is 70:30) with functional TiO2nanoparticles, which was surface‐modified by the silane coupling agent methacryloxy propyl trimethoxyl silane (KH570) to attach active ends. The structure and properties of the copolymer were characterized by FT‐IR, FE‐SEM, differential scanning calorimetry, thermogravimetric analysis, ultraviolet‐visible spectra, and discoloration. Characterization revealed that functional TiO2particles were grafted onto the chain of the acrylate copolymer and the acrylate copolymer showed excellent photo‐oxidative stability and transparency. The acrylate copolymer was applied to protect and consolidate ancient ivory by surface coating without destruction of chemical structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43291.
Toughening effect of CPE on ASA/SAN binary blends at different temperatures
Authors: Mao Zepeng , Zhang Jun
Published: February 2016

The effect of chlorinated polyethylene (CPE) on the impact toughness of acrylonitrile–styrene–acrylic (ASA) terpolymer/styrene–acrylonitrile copolymer (SAN) binary blends (25/75, w/w) was systematically investigated at three different temperatures (−30  °C, 0  °C, and 23  °C). With the addition of 60 phr CPE, the impact strength increased by 11 times at 23  °C and 10 times at 0  °C. However, the toughening effect was not obvious when the testing temperature was −30  °C. Since the glass‐transition temperature (Tg) of CPE was about −18.3  °C as measured with dynamic mechanical analysis tests, the polymeric chains of CPE have been “frozen out” at −30  °C. As a result, CPE evidently cannot improve the toughness of the blend system. The morphology of impact‐fractured surfaces observed by scanning electron microscopy also confirmed the effect of CPE on the impact toughness of ASA/SAN binary blends. The heat distortion temperature remained almost unchanged, indicating that the improvement in toughness did not sacrifice heat resistance. Furthermore, other mechanical properties were evaluated, and the possible interactions among components of the blends were also analyzed by Fourier transform infrared spectra. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43353.
Poly(lactic acid) biocomposites reinforced with ultrafine bamboo‐char: Morphology, mechanical, thermal, and water absorption properties
Authors: Qian Shaoping , Sheng Kuichuan , Yao Wenchao , Yu Hui
Published: February 2016

In this study, ultrafine bamboo‐char (BC) was introduced into poly(lactic acid) (PLA) matrix to improve mechanical and thermal properties of PLA based biodegradable composites. PLA/BC biocomposites were fabricated with different BC contents by weight. Uniform dispersion of BC in the PLA matrix and good interactionviaphysical and chemical interfacial interlocks were achieved. The maximum tensile strength and tensile modulus values of 14.03 MPa and 557.74 MPa were obtained when 30% BC was used. Impact strength of the biocomposite with 30% BC was increased by 160%, compared to that of pure PLA. DSC analysis illustrated that PLA/BC biocomposites had a better thermal property. Crystallization temperature decreased and maximal crystallinity of 30.30% was observed with 30% BC load. We did not notice significant thermal degradation differences between biocomposites with different BC loadings from TGA. Better water resistance was obtained with the addition of BC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43425.
Antimicrobial carbon materials incorporating copper nano‐crystallites and their PLA composites
Authors: Ilnicka Anna , Walczyk Mariusz , Lukaszewicz Jerzy P. , Janczak Katarzyna , Malinowski Rafal
Published: February 2016

In the first stage, carbon materials were manufactured from chitin and chitosan as the main precursor. Chitin and chitosan were impregnated with Cu2+ ions. Using heat treatment, the organic matter (biopolymers) was transformed into a porous carbon matrix, while copper ions were transformed into copper‐based nano‐crystallites containing copper atoms in a +1 and 0 oxidation state. Such synthesized carbons exhibited high contact antifungal activity, e.g., for sample, CH‐ACu0.1_Ox against R. nigricans the inhibition zone is 10.27 mm. In the second stage, composite polymer films were manufactured by mixing polylactide (PLA) and the obtained microbial carbon material (up to 3 wt % Cu‐carbon content). Despite the very low content of carbon material (3 wt %), the composite PLA films exhibited excellent microbial properties for selected bacteria and fungi, e.g., sample CuCM3%/PLA demonstrated high log10 reduction values of 2.17 and 2.66 for the strains of E. coli and S. aureus, respectively. The composite films, and their components, were examined by means of diversified physicochemical methods like low temperature adsorption of nitrogen, SEM, elemental analysis, XRD, cyclic voltammetry, antifungal, and antibacterial analysis. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43429.
Reinforcement learning behaviors in sponsored search
Authors: Chen Wei , Liu Tie‐Yan , Yang Xinxin
Published: February 2016

This paper is concerned with the modeling of advertiser behaviors in sponsored search. Modeling advertiser behaviors can help search engines better serve advertisers, improve auction mechanism, and forecast future revenue. Previous works on this topic either unrealistically assume advertisers to be able to perceive the states of the sponsored search system and the private information of other advertisers or ignore the differences in advertisers' abilities to optimize their bid strategies. To tackle the problems, we propose viewing sponsored search auctions as partially observable multi‐agent system with private information. Then, we employ a reinforcement learning behavior model to describe how each advertiser responds to this multi‐agent system. The proposed model no longer assumes advertisers to have perfect information access, but instead assumes them to optimize their strategies only based on the partially observed states in the auctions. Furthermore, the model does not specify how the optimization is conducted, but instead uses parameters learned from data to describe different advertisers' abilities in obtaining the optimal strategies. Our experiments on real sponsored search data demonstrate that the proposed model outperforms previous models in predicting the bids and rank positions of the advertisers in the near future. In addition to the accurate prediction of these short‐term behaviors, our study shows another nice property of the proposed model. That is, if all the advertisers behave according to the model, the multi‐agent system of sponsored search will converge to a locally envy‐free equilibrium, under certain conditions. This result establishes a connection between machine‐learned behavior models and game‐theoretic properties of the system. Copyright © 2016 John Wiley & Sons, Ltd.
Brandverhalten von Brettsperrholz
Authors: Klippel Michael , Frangi Andrea
Published: February 2016

Brettsperrholz (BSP) wird zunehmend im modernen Holzbau für Wände, Decken oder Dachelemente als hochwertiges, innovatives und wirtschaftliches Tragelement eingesetzt. Bei sorgfältiger Planung und Ausführung ist es möglich, einen sicheren Einsatz von BSP auch in Gebäuden mit erhöhten Brandschutzanforderungen und gemäß den Anforderungen von Tragwerksnormen (z. B. EN 1995‐1‐1 und EN 1995‐1‐2) [1, 2] zu gewährleisten. Weltweit wurden bereits zahlreiche Brandversuche mit BSP durchgeführt, um den Einfluss unterschiedlicher Querschnittsaufbauten sowie verschiedener Klebstoffe auf den Feuerwiderstand von Decken‐ und Wandelementen aus BSP zu untersuchen. Dieser Beitrag gibt einen Überblick über die umfangreichen experimentellen Untersuchungen, wichtige Erkenntnisse werden zusammengefasst und Empfehlungen für die Brandbemessung von BSP erläutert. Die Untersuchungen zeigen, dass eine ausreichende Datengrundlage existiert, um das Brandverhalten von BSP zuverlässig zu beschreiben.
Cooperation of Aspergillus nidulans enzymes increases plant polysaccharide saccharification
Authors: Tramontina Robson , Robl Diogo , Maitan‐Alfenas Gabriela Piccolo , de Vries Ronald P.
Published: February 2016

Efficient polysaccharide degradation depends on interaction between enzymes acting on the main chain and the side chains. Previous studies demonstrated cooperation between several enzymes, but not all enzyme combinations have been explored. A better understanding of enzyme cooperation would enable the design of better enzyme mixtures, optimally profiting from synergistic effects. In this study, we analyzed the cooperation of several enzymes involved in the degradation of xylan, glucan, xyloglucan and crude plant biomass from Aspergillus nidulans by single and combined incubations with their polymeric substrate. Positive effects were observed between most enzymes, although not always to the same extent. Moreover, the tailor made cocktails formulated in this study resulted in efficient release of glucose from plant biomass. This study also serves as an example for the complex cooperation that occurs between enzymes in plant biomass saccharification and how expression in easily‐accessible hosts, such as Pichia pastoris, can help in revealing these effects.
Expression of type 2 diacylglycerol acyltransferse gene DGTT1 from Chlamydomonas reinhardtii enhances lipid production in Scenedesmus obliquus
Authors: Chen Chun‐Yen , Kao Ai‐Ling , Tsai Zheng‐Chia , Chow Te‐Jin , Chang Hsin‐Yueh , Zhao Xin‐Qing , Chen Po‐Ting , Su Hsiang‐Yen , Chang Jo‐Shu
Published: February 2016

Microalgal strains of Scenedesmus obliquus have the great potential for the production of biofuels, CO2 fixation, and bioremediation. However, metabolic engineering of S. obliquus to improve their useful phenotypes are still not fully developed. In this study, S. obliquus strain CPC2 was genetically engineered to promote the autotrophic growth and lipid productivity. The overexpression plasmid containing the type 2 diacylglycerol acyltransferse (DGAT) gene DGTT1 from Chlamydomonas reinhardtii was constructed and transformed into S. obliquus CPC2, and the positive transformants were obtained. The expression of DGTT1 gene was confirmed by reverse transcription PCR analysis. Enhanced lipid content of the transformant S. obliquus CPC2‐G1 by nearly two‐fold was observed. The biomass concentration of the recombinant strains was also 29% higher than that of the wild‐type strain. Furthermore, the recombinant strain CPC2‐G1 was successfully grown in 40 L tubular type photobioreactor and open pond system in an outdoor environment. The lipid content, biomass concentration, and biomass productivity obtained from 40 L tubular PBR were 127.8% 20.0%, and 232.6% higher than those obtained from the wild‐type strain. The major aim of this work is to develop a tool to genetically engineer an isolated S. obliquus strain for the desired purpose. This is the first report that genetic engineering of S. obliquus has been successful employed to improve both the microalgal cell growth and the lipid production.
Yeast Cyclophilins Prevent Cold Denaturation of Proteins
Authors: Naicker Mahendran Chinnamara , Kim Yang‐Hee , Lee Kyunghee , Im Hana
Published: February 2016

Freezing environments are one of the major challenges faced by many organisms, including Saccharomyces cerevisiae. Exposure to low temperatures reduces protein folding rates and induces the cold denaturation of proteins, necessitating aid from chaperones. In a previous study, we identified 19 chaperone genes, the deletion of which makes the host more vulnerable to freeze‐and‐thaw treatments. Among those, peptidyl–prolyl cis–trans isomerases (PPIases) were the most frequently identified. At low temperatures, peptidyl–prolyl isomerization is a rate‐limiting step in protein folding, and folding intermediates, which are prone to protein aggregation, tend to accumulate. To characterize their mode of function, the identified PPIases were overexpressed in Escherichia coli. Not only did they increase the survival of E. coli during freeze‐and‐thaw treatment at –20 °C, but they also protected β‐galactosidase against freeze‐induced protein denaturation. Purified Cpr1p facilitated the refolding of a slow‐folding substrate protein in vitro. These results suggest that the identified PPIases enhance cold survival of cells by preventing cold‐induced protein denaturation and promoting protein folding.
Comparison of LC‐UV and LC–MS methods for simultaneous determination of teriflunomide, dimethyl fumarate and fampridine in human plasma: application to rat pharmacokinetic study
Authors: Suneetha A. , Raja Rajeswari K.
Published: February 2016

This study describes a comparison between LC‐UV and LC–MS method for the simultaneous analyses of a few disease‐modifying agents of multiple sclerosis. Quantitative determination of fampridine (FAM), teriflunomide (TFM) and dimethyl fumarate (DMF) was performed in human plasma with the recovery values in the range of 85–115%. A reversed‐phase high‐performance liquid chromatography (HPLC) with UV as well as MS detection is used. The method utilizes an XBridge C18 silica column and a gradient elution with mobile phase consisting of ammonium formate and acetonitrile at a flow rate of 0.5 mL min−1. The method adequately resolves FAM, TFM and DMF within a run time of 15 min. Owing to low molecular weights, the estimation of DMF and FAM is more versatile in UV than MS detection. With LC‐UV, the detection limits of FAM, TFM and DMF were 0.1, 0.05, 0.05 μg and the quantification limit for all the analytes was 1 μg. With LC–MS, the detection and quantification limits for all of the analytes were 1 and 5 ng, respectively. The two techniques were completely validated and shown to be reproducible and sensitive. They were applied to a pharmacokinetic study in rats by a single oral dose. Copyright © 2016 John Wiley & Sons, Ltd.
Evidence for cerebral edema, cerebral perfusion, and intracranial pressure elevations in acute mountain sickness
Authors: DiPasquale Dana M. , Muza Stephen R. , Gunn Andrea M. , Li Zhi , Zhang Quan , Harris N. Stuart , Strangman Gary E.
Published: February 2016

Introduction

We hypothesized that cerebral alterations in edema, perfusion, and/or intracranial pressure (ICP) are related to the development of acute mountain sickness (AMS).

Methods

To vary AMS, we manipulated ambient oxygen, barometric pressure, and exercise duration. Thirty‐six subjects were tested before, during and after 8 h exposures in (1) normobaric normoxia (NN; 300 m elevation equivalent); (2) normobaric hypoxia (NH; 4400 m equivalent); and (3) hypobaric hypoxia (HH; 4400 m equivalent). After a passive 15 min ascent, each subject participated in either 10 or 60 min of cycling exercise at 50% of heart rate reserve. We measured tissue absorption and scattering via radio‐frequency near‐infrared spectroscopy (NIRS), optic nerve sheath diameter (ONSD) via ultrasound, and AMS symptoms before, during, and after environmental exposures.

Results

We observed significant increases in NIRS tissue scattering of 0.35 ± 0.11 cm−1 (P = 0.001) in subjects with AMS (i.e., AMS+), consistent with mildly increased cerebral edema. We also noted a small, but significant increase in total hemoglobin concentrations with AMS+, 3.2 ± 0.8 μmolL−1 (P < 0.0005), consistent with increased cerebral perfusion. No effect of exercise duration was found, nor did we detect differences between NH and HH. ONSD assays documented a small but significant increase in ONSD (0.11 ± 0.02 mm; P < 0.0005) with AMS+, suggesting mildly elevated ICP, as well as further increased ONSD with longer exercise duration (P = 0.005).

Conclusion

In AMS+, we found evidence of cerebral edema, elevated cerebral perfusion, and elevated ICP. The observed changes were small but consistent with the reversible nature of AMS.
Palladium Supported on Nanodiamonds as an Efficient Catalyst for the Hydrogenating Deamination of Benzonitrile and Related Compounds
Authors: Gupta Neeraj , Ding Yuxiao , Feng Zhenbao , Su Dangsheng
Published: February 2016

Palladium nanoparticles were successfully prepared on a nanodiamond (ND) support and used for the hydrogenating deamination of benzonitrile, aromatic imines, and amines for the first time. The developed methodology was further used for the in situ conversion of aldehydes into hydrocarbons, including a biomass‐derived model compound. The activity of the catalyst was compared with palladium supported on activated carbon (AC) under identical conditions and the performance of Pd/ND was found to be superior to Pd/AC. The origin of the difference in the catalytic performance was considered. Finally, an attempt has been made to understand the mechanism through the identification of the side products by GCMS analysis.