bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of interface microscopic processes in organic bilayer structures and their effect on photovoltaic device performance
Authors: Liu Feilong , Crone Brian K. , Paul Ruden P. , Smith Darryl L.
Published: January 2013

We explore theoretically the effect of incorporating a thin tunnel barrier between the electron and hole transport layers of organic heterojunction photovoltaic devices. Macroscopic device characteristics (such as short-circuit current, open-circuit voltage, and power efficiency) are related to microscopic processes (such as exciton diffusion, dissociation, and recombination). We show that a tunnel barrier that alters the rates of different transfer processes at the interface between the electron and hole transport layers can significantly affect the efficiency of organic photovoltaic devices.
Growth, structural, and magnetic characterization of epitaxial Co2MnSi films deposited on MgO and Cr seed layers
Authors: Ortiz G. , García-García A. , Biziere N. , Boust F. , Bobo J. F. , Snoeck E.
Published: January 2013

We report detailed structural characterization and magneto-optical Kerr magnetometry measurements at room temperature in epitaxial Co2MnSi thin films grown on MgO(001) and Cr(001) buffered MgO single crystals prepared by sputtering. While Co2MnSi/Cr//MgO(001) films display the expected cubic anisotropy, the magnetization curves obtained for Co2MnSi//MgO(001) samples exhibit a superimposed in-plane uniaxial magnetic anisotropy. The evolution of magnetization with film thickness points to a relevant interfacial Co2MnSi-buffer layer (Cr or MgO) contribution which competes with magnetic properties of bulk Co2MnSi, resulting in a drastic change in the magnetism of the whole sample. The origin of this interfacial magnetic anisotropy is discussed and correlated with our structural studies.
The internal structure of suspensions in uniaxial elongation
Authors: Sinha-Ray S. , Fezzaa K. , Yarin A. L.
Published: January 2013

Self-thinning of a tiny thread of suspension of glass beads or rods is explored using high-speed X-ray phase-contrast imaging. The overall fluid mechanical pattern is provided by the thread-thinning rate, while the X-ray imaging of the evolution of the suspension internal structure sheds light onto the interplay between fluid mechanics and rheology. In particular, we measured in real time the motion and re-orientation of the individual glass rods in self-thinning liquid threads for the first time, and established the link between these micromechanical phenomena and macroscopic elongational suspension flow. The results with the rod-like particles raise questions on the validity of the common assumption of the affinity of the macroscopic flow kinematics and particle motion.
A plasmonically enhanced charge generation layer for tandem organic light emitting device
Authors: Yan Fei , Wei Sun Xiao
Published: January 2013

We studied silver nanoparticles (Ag NPs) as an n-type dopant in the charge generation connector of tandem organic light-emitting diodes. Due to the localized surface plasmonic resonance and quantum size effects, Ag NPs are more active and easy to lose electron comparing to bulk or film forms of Ag, and can work as excellent n-type dopant. For the tandem device with Ag NPs in the charge generation layer, the current efficiency is more than doubled and the driving voltage is less than twice compared to one single emission unit device.
Orbital structure of FeTiO3 ilmenite investigated with polarization-dependent X-ray absorption spectroscopy and band structure calculations
Authors: Chen S. W. , Huang M. J. , Lin P. A. , Jeng H. T. , Lee J. M. , Haw S. C. , Chen S. A. , Lin H. J. , Lu K. T. , Chen D. P. , Dou S. X. , Wang X. L. , Chen J. M.
Published: January 2013

We explored the orbital structure of FeTiO3 with polarization-dependent x-ray absorption spectra complemented with electronic structure calculations. The electronic structure, near the bottom of conduction band, is composed of O 2p and Ti 3d orbitals. Ti 3d/4p hybridization dominantly lies on the ab plane. The highly delocalized Ti 4p orbital might hybridize with O 2p orbital and even extend to the next-neighbor Fe atom whereby establishing a linear orbital combination of Ti-O-Fe. A clear picture of the orbital construction in FeTiO3 will help to elucidate the paths of pressure-induced charge transfer and other physical or magnetic characteristics.
A single crystal lead magnesium niobate-lead titanate multilayer-stacked cryogenic flextensional actuator
Authors: Xu Tian-Bing , Tolliver Laura , Jiang Xiaoning , Su Ji
Published: January 2013

A “33” mode single crystal lead magnesium niobate-lead titanate flextensional actuator with large displacement, high load capability, and broad bandwidth was designed, prototyped, and evaluated at temperatures ranging from room temperature to cryogenic temperatures. Measuring 27.4 × 10 × 13.6 mm (height) overall and weighing 9.2 g, the actuator generates a 96.5 μm displacement in the Z-direction at 170 Vrms. The level of displacement remained constant under compressive loads up to 5 kg force. The actuator maintains 66% of its room temperature displacement at −196 °C. The measured displacements matched well with those modeled using ANSYS finite element analysis.
Defects versus grain size effects on the ferromagnetism of ZrO2 nanocrystals clarified by positron annihilation
Authors: Wang D. D. , Qi N. , Jiang M. , Chen Z. Q.
Published: January 2013

Undoped ZrO2 nanocrystals were annealed in open air from 100 °C to 1300 °C. X-ray diffraction and transmission electron microscope were used to study the structure change and grain growth. Both the methods reveal that the ZrO2 grain size has very slight increase after annealing up to 900 °C. Positron annihilation measurements reveal a high concentration of vacancy defects which most probably exist in the grain boundary region. Thermal annealing above 500 °C causes recovery of these defects, and after annealing at 1200 °C, most of them are removed. Room temperature ferromagnetism is observed for the sample annealed at 100 °C and 500 °C. The magnetization becomes very weak after the nanocrystals are annealed at 700 °C, and it almost disappears at 1000 °C. It is clear that the intrinsic ferromagnetism in our ZrO2 nanocrystals is mostly related with the interfacial defects instead of grain size effects.
Enhanced contribution of surface state and modification of magnetoresistance in FexBi2−xSe3 topological insulator crystals
Authors: Lv L. , Zhang M. , Wei Z. T. , Yang L. Q. , Yang X. S. , Zhao Y.
Published: January 2013

Magnetic atomic-doped topological insulator crystals with the formula FexBi2−xSe3 were fabricated using the self-flux method and their electrical and magnetic transport properties were studied. All samples showed weakly metallic resistivity and the resistivity increased monotonously as the Fe concentration increased. Conductivity was modified by Fe at high- and low-temperature regions via different mechanisms, which could be explained by the freezing of bulk carriers around 30 K. For highly doped samples, simultaneous crossovers in the curves of temperature dependent of resistivity (ρ-T) and temperature dependent of magnetoresistance (MR-T) at low temperature were observed, indicating that the contribution of the surface state was significantly improved. No obvious enhanced surface effect was observed in samples doped with low concentration of Fe, but the MR was enhanced significantly in low-doped samples and suppressed by high Fe content. Magnetic-field-induced metal-insulator transitions were observed in the samples with the largest MR values. The change in MR was related to three mechanisms: phonon scattering effect, magnetic ordering, and spin disorder scattering.
Scientists alarmed by rapidly shrinking Arctic ice cap
Authors: Kramer David
Published: January 2013

With summertime disappearance of polar sea ice expected as early as this decade, various geoengineering schemes have been proposed for mitigation. But each carries baggage.
Dark-matter search gets started deep in Sanford Lab
Authors: Feder Toni
Published: January 2013

If more experiments, in particular the Long-Baseline Neutrino Experiment, go forward, what scientists had hoped to get in one go will instead be realized incrementally.
Bulk Metallic Glasses
Authors: Schroers Jan
Published: January 2013

Stronger than steels but able to be shaped and molded like plastics, bulk metallic glasses are the quintessential engineering materials.
Spatial Development of Producer Services in the Chinese Urban System
Authors: Yang Fiona F , Yeh Anthony G O
Published: January 2013

The Chinese economy has transformed from the development of industries in the early economic reform period of the 1980s to the development of service industries in the 2000s and, more recently, the emergence of producer service industries. Producer services have become increasingly important to the Chinese economy. Most studies on producer services in China mainly focus on individual cities. Spatial development of producer services at the regional and national levels is relatively less examined. In this paper we analyze the growth and location of producer services in the Chinese urban system. The study also shows that producer services are becoming spatially more concentrated across the urban system. As producer services that are important in generating economic development are more likely to be located in large metropolitan areas, they tend to reinforce the competitiveness of large cities. Moreover, the uneven spatial development of producer services suggests that small and medium cities need to conduct careful market studies and analyses on their ability to attract producer service industries before they initiate large central business district development projects and invest in massive construction of offices.
Noxious Neighbours? Interrogating the Impacts of Sex Premises in Residential Areas
Authors: Hubbard Phil , Boydell Spike , Crofts Penny , Prior Jason , Searle Glen
Published: January 2013

Premises associated with commercial sex—including brothels, striptease clubs, sex cinemas, and sex shops—have increasingly been accepted as legitimate land uses, albeit ones whose location needs to be controlled because of assumed ‘negative externalities’. However, the planning and licensing regulations excluding such premises from areas of residential land use are often predicated on assumptions of nuisance that have not been empirically substantiated. Accordingly, this paper reports on a survey of those living close to sex industry premises in New South Wales, Australia. The results suggest that although some residents have strong moral objections to sex premises, in general residents note few negative impacts on local amenity or quality of life, with distance from a premise being a poor predictor of residents' experiences of nuisance. These findings are considered in relation to the literatures on sexuality and space given regulation which ultimately appears to reproduce heteronormative moralities rather than respond to genuine environmental nuisances.
Identification of T6SS-dependent effector and immunity proteins by Tn-seq in
Vibrio cholerae
Authors: Dong Tao G. , Ho Brian T. , Yoder-Himes Deborah R. , Mekalanos John J.
Published: January 2013

Type VI protein secretion system (T6SS) is important for bacterial competition through contact-dependent killing of competitors. T6SS delivers effectors to neighboring cells and corresponding antagonistic proteins confer immunity against effectors that are delivered by sister cells. Although T6SS has been found in more than 100 gram-negative bacteria including many important human pathogens, few T6SS-dependent effector and immunity proteins have been experimentally determined. Here we report a high-throughput approach using transposon mutagenesis and deep sequencing (Tn-seq) to identify T6SS immunity proteins in
Vibrio cholerae
. Saturating transposon mutagenesis was performed in wild type and a T6SS null mutant. Genes encoding immunity proteins were predicted to be essential in the wild type but dispensable in the T6SS mutant. By comparing the relative abundance of each transposon mutant in the mutant library using deep sequencing, we identified three immunity proteins that render protection against killing by T6SS predatory cells. We also identified their three cognate T6SS-secreted effectors and show these are important for not only antibacterial and antieukaryotic activities but also assembly of T6SS apparatus. The lipase and muramidase T6SS effectors identified in this study underscore the diversity of T6SS-secreted substrates and the distinctly different mechanisms that target these for secretion by the dynamic T6SS organelle.
Application of Stock Density Indices as a Tool for Broad-Scale Population Assessment for Four Cyprinid Species in Central Italy
Authors: Pedicillo Giovanni , Lorenzoni Massimo , Carosi Antonella , Ghetti Lucia
Published: January 2013

Stock-density indices are standardized methods for analyzing length-frequency data that quantify the length structure of a fish population into length categories that are of interest to recreational anglers. We adapted North American relative stock density (RSD) and proportional stock density (PSD) indices to four Italian endemic or native cyprinid species by means of two methods. In accordance with the traditional approach, the benchmarks of length categories were established according to Gabelhouse's percentage classification and calculated on the basis of the largest individual in the data set for each species. In the second method, asymptotic length and size at maturity were used to define the length categories for index calculation. Both methods were tested on length-frequency data from fish collected from sampling sites in the Tiber River basin. The results showed that the traditional approach displayed better applicability, required less sampling effort, and provided a better insight into the length structure of the fish populations studied.

Received January 17, 2012; accepted November 4, 2012
Linear and Nonlinear Optical Properties of Novel Multi-branched Oligomers
Authors: Gong Li-jing , Wang Ying-hui , Kang Zhi-hui , Huang Tian-hao , Lu Ran , Zhang Han-zhuang
Published: January 2013

We investigate the fluorene-vinylene unit dependent photo-physical properties of multi-branched truxene based oligomers (Tr-OFVn, n=1–4) employing steady-state absorption and emission spectroscopy, transient absorption spectroscopy, two-photon fluorescence, and z-scan technique. The results show that the increasing of fluorene-vinylene unit leads to a red-shift in the spectra of absorption and fluorescence, and shortens the excited state lifetime. Meanwhile, two-photon fluorescence efficiency and two-photon absorption cross section of truxene based oligomers gradually enhance in company with the extension of π-conjugated length. In addition, the values of two-photon absorption cross section modeled on the sum-over-state approach agree well with the experimental ones. The results indicate multi-branched truxene based oligomers bearing oligo(fluorene-vinylene) arms are promising organic materials for two-photon applications.
Density Functional Theory Study on Interaction between Catechin and Thymine
Authors: Cai Wan-fei , Zheng Yan , Li Lai-cai , Tian An-min
Published: January 2013

The interacting patterns and mechanism of the catechin and thymine have been investigated with the density functional theory Becke's three-parameter nonlocal exchange functional and the Lee, Yang, and Parr nonlocal correlation functional (B3LYP) method by 6−31+G* basis set. Thirteen stable structures for the catechin-thymine complexes have been found which form two hydrogen bonds at least. The vibrational frequencies are also studied at the same level to analyze these complexes. The results indicated that catechin interacted with thymine by three different hydrogen bonds as N—H···O, C—H···O, O—H···O and the complexes are mainly stabilized by the hydrogen bonding interactions. Theories of atoms in molecules and natural bond orbital have been adopted to investigate the hydrogen bonds involved in all systems. The interaction energies of all complexes have been corrected for basis set superposition error, which are from −18.15 kJ/mol to −32.99 kJ/mol. The results showed that the hydrogen bonding contribute to the interaction energies dominantly. The corresponding bonds stretching motions in all complexes are red-shifted relative to that of the monomer, which is in agreement with experimental results.
Hydrogen-bonded Intramolecular Charge Transfer Excited State of Dimethylaminobenzophenone using Time Dependent Density Functional Theory
Authors: Chu Yu-ling , Yang Zhong , Pan Zhe-feng , Liu Jing , Han Yue-yi , Ding Yong , Song Peng
Published: January 2013

Density functional theory and time-dependent density-functional theory have been used to investigate the photophysical properties and relaxation dynamics of dimethylaminobenzophenone (DMABP) and its hydrogen-bonded DMABP-MeOH dimer. It is found that, in non-polar aprotic solvent, the transitions from S0 to S1 and S2 states of DMABP have both n→π* and π→π* characters, with the locally excited feature mainly located on the C=O group and the partial CT one characterized by electron transfer mainly from the dimethylaminophenyl group to the C=O group. But when the intermolecular hydrogen bond C=O···H—O is formed, the highly polar intramolecular charge transfer character switches over to the first excited state of DMABP-MeOH dimer and the energy difference between the two low-lying electronically excited states increases. To gain insight into the relaxation dynamics of DMABP and DMABP-MeOH dimer in the excited state, the potential energy curves for conformational relaxation are calculated. The formation of twisted intramolecular charge transfer state via diffusive twisting motion of the dimethylamino/dimethylaminophenyl groups is found to be the major relaxation process. In addition, the decay of the S1 state of DMABP-MeOH dimer to the ground state, through nonradiative intermolecular hydrogen bond stretching vibrations, is facilitated by the formation of the hydrogen bond between DMABP and alcohols.
Feature Designed Growth of 3D Flower-like SiO2 Growing on Polyethyleneimine Modified CaCO3 Microparticles
Authors: Zheng Xin-mei , Qi Yan-xing , Lu Gong-xuan
Published: January 2013

We report on the ability to create complex 3D flower-like SiO2 in vitro via CaCO3 microparicles supported by polyethyleneimine mediated biosilicification under experimentally altered chemical influences. The morphology, structure, composition of the product have been investigated with the X-ray photoelectron spectrum, scanning electron microscope, transmission electron microscope, and energy-dispersive spectroscopy. The overall morphologies could be controlled to shift from a characteristic network of flower-like silica sphere to a sheet-like structure by adjusting physical adsorption of different amount of polyethyleneimine onto the surface of the CaCO3 microparticles.
Interaction of Egg-Sphingomyelin with DOPC in Langmuir Monolayers
Authors: Hao Chang-chun , Sun Run-guang , Zhang Jing
Published: January 2013

Lipid rafts are a dynamic microdomain structure found in recent years, enriched in sphingolipids, cholesterol and particular proteins. The change of structure and function of lipid rafts could result in many diseases. In this work, the monolayer miscibility behavior of mixed systems of Egg-Sphingomyelin (ESM) 1 with 2-dioleoyl-sn-glycero-3-phosphocholine was investigated in terms of mean surface area per molecule and excess molecular area ΔAex at certain surface pressure, surface pressure and excess surface pressure Δπex at certain mean molecular area. The stability and compressibility of the mixed monolayers was assessed by the parameters of surface excess Gibbs free energy ΔGex, excess Helmholtz energy ΔHex and elasticity. Thermodynamic analysis indicates ΔAex and Δπex in the binary systems with positive deviations from the ideal behavior, suggesting repulsive interaction. The maximum of ΔGex and ΔHex was at the molar fraction of ESM of 0.6, demonstrating the mixed monolayer was more unstable. The repulsive interaction induced phase separation in the monolayer.
Melamine/Stearic Acid Composite Nanowires and Vesicles with an Intercalated Nanostructure Prepared through NCCM Method
Authors: Guo Juan , Chen Dao-yong
Published: January 2013

A solvent-non-solvent method invented in our laboratory for preparing non-covalently connected micelles (NCCM) was used to intercalate melamine (MA) molecules into stearic acid (SA) bilayers to form the composite nanoparticles with an intercalated nanostructure in which a melamine bilayer is sandwiched between two stearic acid bilayers, NCCM method helps to sufficiently mix the two components in nanospace and meanwhile inhibits the strong tendency of self-crystallization of MA, leading to the intercalation. Although the nanoparticles have a regular inner structure, the primary MA/SA nanoparticles have an irregular morphology. Regular nanoparticles were obtained through annealing the suspension of the primary nanoparticles. Through annealing at different temperatures, the MA/SA composite nanowires and vesicles with an intercalated structure were prepared respectively. It is proposed that the morphological change results from the change in the intercalated structure.
Synthesis and Optical Properties of ZnO Nanoparticles in Submicron PS Hollow Reactors
Authors: Huang Xue-feng , Ju Fei-fei , Wang Mo-zhen , Ge Xue-wu
Published: January 2013

ZnO nanoparticles were first encapsulated in submicron PS hollow microspheres through two-step swelling process of core-shell structured PMMA/PS (PMMA: polymethyl methaorylate) microspheres in acid-alkali solution, and the ZnO precursors, i.e. the ethanol solutions of (CH3COO)2Zn and LiOH. The transmission electron microscope, X-ray diffraction, and thermogravimetric analysis results show that the feeding order of ethanol solutions of (CH3COO)2Zn and LiOH in the second swelling step has great influence on the loading efficiency and the size of ZnO nanoparticles, but little on their crystal form. The photoluminescence and UV-Vis absorption behavior of ZnO/PS microspheres show that the PS shell can effectively avoid the fluorescence quenching effect.
New Li-ion Battery Evaluation Research Based on Thermal Property and Heat Generation Behavior of Battery
Authors: Lv Zhe , Guo Xun , Qiu Xin-ping
Published: January 2013

We do a new Li-ion battery evaluation research on the effects of cell resistance and polarization on the energy loss in batteries based on thermal property and heat generation behavior of battery. Series of 18650 cells with different capacities and electrode materials are evaluated by measuring input and output energy which change with charge-discharge time and current. Based on the results of these tests, we build a model of energy loss in cells' charge-discharge process, which include Joule heat and polarization heat impact factors. It was reported that Joule heat was caused by cell resistance, which included DC-resistance and reaction resistance, and reaction resistance could not be easily obtained through routine test method. Using this new method, we can get the total resistance R and the polarization parameter η. The relationship between R, η, and temperature is also investigated in order to build a general model for series of different Li-ion batteries, and the research can be used in the performance evaluation, state of charge prediction and the measuring of consistency of the batteries.
Effect of Surface Protonation on Device Performance and Dye Stability of Dye-sensitized TiO2 Solar Cell
Authors: Wu Kun-jie , Shen Kai , Yu Yang , Wang De-liang
Published: January 2013

A flat thin TiO2 film was employed as the photo-electrode of a dye sensitized solar cell (DSSC), on which only a geometrical mono-layer of dye was attached. The effect of surface protonation by HCl chemical treatment on the performance of DSSCs was studied. The results showed that the short-circuit current Jsc increased significantly upon the HCl treatment, while the open-circuit voltage Voc decreased slightly. Compared to the untreated DSSC, the Jsc and energy conversion efficiency was increased by 31% and 25%, respectively, for the 1 mol/L HCl treated cell. TiO2 surface protonation improved electronic coupling between the chemisorbed dye and the TiO2 surface, resulting in an enhanced electron injection. The decreased open-circuit voltage after TiO2 surface protonation was mainly due to the TiO2 conduction band edge downshift and was partially caused by increased electron recombination with the electrolyte. In situ Raman degradation study showed that the dye stability was improved after the TiO2 surface protonation. The increased dye stability was contributed by the increased electron injection and electron back reaction with the electrolyte under the open-circuit condition.
Optical Remote-sensing Monitoring and Forecasting of Atmospheric Pollution in Huaibei Area, China
Authors: Li Su-wen , Xie Pin-hua , Jiang En-hua , Zhang Yong , Dai Hai-feng
Published: January 2013

Huaibei is an energy city. Coal as the primary energy consumption brings a large number of regional pollution in Huaibei area. Differential optical absorption spectroscopy (DOAS) as optical remote sensing technology has been applied to monitor regional average concentrations and inventory of nitrogen dioxide, sulfur dioxide and ozone. DOAS system was set up and applied to monitor the main air pollutants in Huaibei area. Monitoring data were obtained from 7 to 28 August, 2011. Monitoring results show measurements in controlling pollution are effective, and emissions of pollutants are up to the national standard in Huaibei area. Prediction model was also created to track changing trend of pollutions. These will provide raw data support for effective evaluation of environmental quality in Huaibei area.
Bayesian analysis of gene essentiality based on sequencing of transposon insertion libraries
Authors: DeJesus Michael A. , Zhang Yanjia J. , Sassetti Christopher M. , Rubin Eric J. , Sacchettini James C. , Ioerger Thomas R.
Published: January 2013

Motivation: Next-generation sequencing affords an efficient analysis of transposon insertion libraries, which can be used to identify essential genes in bacteria. To analyse this high-resolution data, we present a formal Bayesian framework for estimating the posterior probability of essentiality for each gene, using the extreme-value distribution to characterize the statistical significance of the longest region lacking insertions within a gene. We describe a sampling procedure based on the Metropolis–Hastings algorithm to calculate posterior probabilities of essentiality while simultaneously integrating over unknown internal parameters.

Results: Using a sequence dataset from a transposon library for Mycobacterium tuberculosis, we show that this Bayesian approach predicts essential genes that correspond well with genes shown to be essential in previous studies. Furthermore, we show that by using the extreme-value distribution to characterize genomic regions lacking transposon insertions, this method is capable of identifying essential domains within genes. This approach can be used for analysing transposon libraries in other organisms and augmenting essentiality predictions with statistical confidence scores.

Availability: A python script implementing the method described is available for download from http://saclab.tamu.edu/essentiality/.

Contact:  michael.dejesus@tamu.edu or ioerger@cs.tamu.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Large size scatter of passively evolving lensed Galaxies at z ∼ 2 in CLASH
Authors: Fan Lulu , Chen Yang , Er Xinzhong , Li Jinrong , Lin Lin , Kong Xu
Published: January 2013

In a systematic search over 11 cluster fields from Cluster Lensing And Supernova survey with Hubble (CLASH), we identify 10 passively evolving massive galaxies at redshift z ∼ 2. We derive the stellar properties of these galaxies using Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3)/Advanced Camera for Surveys (ACS) multiband data, together with Spitzer IRAC observations. We also deduce the optical rest-frame effective radius of these high-redshift objects. The derived stellar masses and measured effective radii have been corrected by the lensing magnification factors, which are estimated by simply adopting the spherical NFW model for the foreground cluster lens. The observed near-IR images, obtained by HST WFC3 camera with high spatial resolution and lensed by the foreground clusters, enable us to study the structures of such systems. Nine out of ten galaxies have on average three times smaller effective radius than local early-type Galaxies (ETGs) of similar stellar masses, in agreement with previous works at redshift 1.5 < z < 2.5. Combined with literature data for z ∼ 2, we find that the mass-normalized effective radius scales with redshift as re/M0.56⋆∝(1 + z)− 1.13. We confirm that their size distribution shows a large scatter: from normal size to ∼5 times smaller compared to local ETGs with similar stellar masses. The 1σ scatter σlog re of the size distribution is 0.22 and 0.34 at z ∼ 1.6 and z ∼ 2.1, respectively. The observed large size scatter has to be carefully taken into account in galaxy evolution model predictions.
Activation of Triggering Receptor Expressed on Myeloid Cells-1 Protects Monocyte from Apoptosis through Regulation of Myeloid Cell Leukemia-1
Authors: Cai MeiTing , Chen QiXing , Chen Chi , Liu XiWang , Hou JinChao , Zeng CongLi , Shu Qiang , Fang XiangMing
Published: January 2013

Background:

Triggering receptor expressed on myeloid cells-1 (TREM-1) can amplify the proinflammatory response and may contribute to the pathogenesis of inflammatory disease such as sepsis. However, the role of TREM-1 in monocyte fate and the detailed molecular mechanisms evoked by TREM-1 are unknown.

Methods:

Adenoviruses overexpressing TREM-1 were constructed and transfected into a monocytic cell line. After activation of TREM-1 by agonist antibody with or without lipopolysaccharide, apoptosis was induced and assayed using flow cytometry. The signaling pathways downstream of TREM-1 were illustrated by inhibitory experiments. Proapoptotic/antiapoptotic protein levels were measured using immunoblot. In addition, the relationship between the expression levels of TREM-1 in monocytes and the magnitude of monocyte apoptosis were analyzed in septic patients.

Results:

Activation of TREM-1 protected monocytes from staurosporine-induced apoptosis. This characteristic was also obtained under lipopolysaccharide stimulation. The protection of TREM-1 against monocyte apoptosis was abrogated after inhibition of extracellular signal–regulated kinase or v-akt murine thymoma viral oncogene homologue signaling. Cross-linking of TREM-1 remarkably up-regulated myeloid cell leukemia-1 protein level, and inhibition of extracellular signal–regulated kinase or v-akt murine thymoma viral oncogene homologue resulted in the reduction of myeloid cell leukemia-1 expression. Inhibition of myeloid cell leukemia-1 abolished the antiapoptotic effect of TREM-1. Furthermore, in septic patients, TREM-1 levels were inversely correlated to the magnitude of apoptosis in monocyte.

Conclusions:

TREM-1 played an important role in apoptosis in monocytes. Activation of TREM-1 protected monocytic cells from apoptosis through activation of both extracellular signal–regulated kinase and v-akt murine thymoma viral oncogene homologue pathways and increased expression of myeloid cell leukemia-1 protein. These findings provide a novel additional mechanism for TREM-1–mediated hyperinflammatory response in monocytes.
Anesthetics Interfere with Axon Guidance in Developing Mouse Neocortical Neurons In Vitro via a γ-Aminobutyric Acid Type A Receptor Mechanism
Authors: Mintz C. David , Barrett Kendall M. S. , Smith Sarah C. , Benson Deanna L. , Harrison Neil L.
Published: January 2013

Background:

The finding that exposure to general anesthetics (GAs) in childhood may increase rates of learning disabilities has raised a concern that anesthetics may interfere with brain development. The generation of neuronal circuits, a complex process in which axons follow guidance cues to dendritic targets, is an unexplored potential target for this type of toxicity.

Methods:

GA exposures were conducted in developing neocortical neurons in culture and in early postnatal neocortical slices overlaid with fluorescently labeled neurons. Axon targeting, growth cone collapse, and axon branching were measured using quantitative fluorescence microscopy.

Results:

Isoflurane exposure causes errors in Semaphorin-3A–dependent axon targeting (n = 77 axons) and a disruption of the response of axonal growth cones to Semaphorin-3A (n = 2,358 growth cones). This effect occurs at clinically relevant anesthetic doses of numerous GAs with allosteric activity at γ-aminobutyric acid type A receptors, and it was reproduced with a selective agonist. Isoflurane also inhibits growth cone collapse induced by Netrin-1, but does not interfere branch induction by Netrin-1. Insensitivity to guidance cues caused by isoflurane is seen acutely in growth cones in dissociated culture, and errors in axon targeting in brain slice culture occur at the earliest point at which correct targeting is observed in controls.

Conclusions:

These results demonstrate a generalized inhibitory effect of GAs on repulsive growth cone guidance in the developing neocortex that may occur via a γ-aminobutyric acid type A receptor mechanism. The finding that GAs interfere with axon guidance, and thus potentially with circuit formation, represents a novel form of anesthesia neurotoxicity in brain development.
Mechanics of plant fruit hooks
Authors: Chen Qiang , Gorb Stanislav N. , Gorb Elena , Pugno Nicola
Published: January 2013

Hook-like surface structures, observed in some plant species, play an important role in the process of plant growth and seed dispersal. In this study, we developed an elastic model and further used it to investigate the mechanical behaviour of fruit hooks in four plant species, previously measured in an experimental study. Based on Euler–Bernoulli beam theory, the force–displacement relationship is derived, and its Young's modulus is obtained. The result agrees well with the experimental data. The model aids in understanding the mechanics of hooks, and could be used in the development of new bioinspired Velcro-like materials.
Walking, running, and resting under time, distance, and average speed constraints: optimality of walk–run–rest mixtures
Authors: Long Leroy L. , Srinivasan Manoj
Published: January 2013

On a treadmill, humans switch from walking to running beyond a characteristic transition speed. Here, we study human choice between walking and running in a more ecological (non-treadmill) setting. We asked subjects to travel a given distance overground in a given allowed time duration. During this task, the subjects carried, and could look at, a stopwatch that counted down to zero. As expected, if the total time available were large, humans walk the whole distance. If the time available were small, humans mostly run. For an intermediate total time, humans often use a mixture of walking at a slow speed and running at a higher speed. With analytical and computational optimization, we show that using a walk–run mixture at intermediate speeds and a walk–rest mixture at the lowest average speeds is predicted by metabolic energy minimization, even with costs for transients—a consequence of non-convex energy curves. Thus, sometimes, steady locomotion may not be energy optimal, and not preferred, even in the absence of fatigue. Assuming similar non-convex energy curves, we conjecture that similar walk–run mixtures may be energetically beneficial to children following a parent and animals on long leashes. Humans and other animals might also benefit energetically from alternating between moving forward and standing still on a slow and sufficiently long treadmill.
Plasticity facilitates sustainable growth in the commons
Authors: Cavaliere Matteo , Poyatos Juan F.
Published: January 2013

In the commons, communities whose growth depends on public good, individuals often rely on surprisingly simple strategies, or heuristics, to decide whether to contribute to the shared resource (at risk of exploitation by free-riders). Although this appears a limitation, we show here how four heuristics lead to sustainable growth when coupled to specific ecological constraints. The two simplest ones—contribute permanently or switch stochastically between contributing or not—are first shown to bring sustainability when the public good efficiently promotes growth. If efficiency declines and the commons is structured in small groups, the most effective strategy resides in contributing only when a majority of individuals are also contributors. In contrast, when group size becomes large, the most effective behaviour follows a minimal-effort rule: contribute only when it is strictly necessary. Both plastic strategies are observed in natural scenarios across scales that present them as relevant social motifs for the sustainable management of public goods.
Revisiting localized deformation in sand with complex systems
Authors: Tordesillas Antoinette , Walker David M. , Andò Edward , Viggiani Gioacchino
Published: January 2013

Complex systems techniques are used to analyse X-ray micro-CT measurements of grain kinematics in Hostun sand under triaxial compression. Network nodes with the
least
mean shortest path length to all other nodes, or highest relative closeness centrality, reside in the region where the persistent shear band ultimately develops. This trend, whereby a group of grains distinguishes themselves from the rest in the sample, remarkably manifests from the onset of loading. The shear band's boundaries and thickness, evident from the network communities' borders and essentially constant mean size, provide corroborating evidence of early detection of strain localization. Our findings raise the possibility that the formation and the location of the persistent shear band may be decided in the nascent stages of loading, well before peak shear stress. Grain-scale digital image correlation strain measurements and statistical tests confirm the results are robust. Moreover, the trends are unambiguously reproduced in a discrete element simulation of plane strain compression.
Coral-associated micro-organisms and their roles in promoting coral health and thwarting diseases
Authors: Krediet Cory J. , Ritchie Kim B. , Paul Valerie J. , Teplitski Max
Published: January 2013

Over the last decade, significant advances have been made in characterization of the coral microbiota. Shifts in its composition often correlate with the appearance of signs of diseases and/or bleaching, thus suggesting a link between microbes, coral health and stability of reef ecosystems. The understanding of interactions in coral-associated microbiota is informed by the on-going characterization of other microbiomes, which suggest that metabolic pathways and functional capabilities define the ‘core’ microbiota more accurately than the taxonomic diversity of its members. Consistent with this hypothesis, there does not appear to be a consensus on the specificity in the interactions of corals with microbial commensals, even though recent studies report potentially beneficial functions of the coral-associated bacteria. They cycle sulphur, fix nitrogen, produce antimicrobial compounds, inhibit cell-to-cell signalling and disrupt virulence in opportunistic pathogens. While their beneficial functions have been documented, it is not certain whether or how these microbes are selected by the hosts. Therefore, understanding the role of innate immunity, signal and nutrient exchange in the establishment of coral microbiota and in controlling its functions will probably reveal ancient, evolutionarily conserved mechanisms that dictate the outcomes of host–microbial interactions, and impact the resilience of the host.
Cutting through the complexity of cell collectives
Authors: Nadell Carey D. , Bucci Vanni , Drescher Knut , Levin Simon A. , Bassler Bonnie L. , Xavier João B.
Published: January 2013

Via strength in numbers, groups of cells can influence their environments in ways that individual cells cannot. Large-scale structural patterns and collective functions underpinning virulence, tumour growth and bacterial biofilm formation are emergent properties of coupled physical and biological processes within cell groups. Owing to the abundance of factors influencing cell group behaviour, deriving general principles about them is a daunting challenge. We argue that combining mechanistic theory with theoretical ecology and evolution provides a key strategy for clarifying how cell groups form, how they change in composition over time, and how they interact with their environments. Here, we review concepts that are critical for dissecting the complexity of cell collectives, including dimensionless parameter groups, individual-based modelling and evolutionary theory. We then use this hybrid modelling approach to provide an example analysis of the evolution of cooperative enzyme secretion in bacterial biofilms.
Behavioural changes and the adaptive diversification of pigeons and doves
Authors: Lapiedra Oriol , Sol Daniel , Carranza Salvador , Beaulieu Jeremy M.
Published: January 2013

What factors determine the extent of evolutionary diversification remains a major question in evolutionary biology. Behavioural changes have long been suggested to be a major driver of phenotypic diversification by exposing animals to new selective pressures. Nevertheless, the role of behaviour in evolution remains controversial because behavioural changes can also retard evolutionary change by hiding genetic variation from selection. In the present study, we apply recently implemented Ornstein–Uhlenbeck evolutionary models to show that behavioural changes led to associated evolutionary responses in functionally relevant morphological traits of pigeons and doves (Columbiformes). Specifically, changes from terrestrial to arboreal foraging behaviour reconstructed in a set of phylogenies brought associated shorter tarsi and longer tails, consistent with functional predictions. Interestingly, the transition to arboreality accelerated the rates of evolutionary divergence, leading to an increased morphological specialization that seems to have subsequently constrained reversals to terrestrial foraging. Altogether, our results support the view that behaviour may drive evolutionary diversification, but they also highlight that its evolutionary consequences largely depend on the limits imposed by the functional demands of the adaptive zone.
HISTONE DEACETYLASE19 Interacts with HSL1 and Participates in the Repression of Seed Maturation Genes inArabidopsisSeedlings
Authors: Zhou Yi , Tan Bin , Luo Ming , Li Yin , Liu Chen , Chen Chen , Yu Chun-Wei , Yang Songguang , Dong Shuai , Ruan Jiuxiao , Yuan Liangbin , Zhang Zhou , Zhao Linmao , Li Chenlong , Chen Huhui , Cui Yuhai , Wu Keqiang , Huang Shangzhi
Published: January 2013

The seed maturation genes are specifically and highly expressed during late embryogenesis. In this work, yeast two-hybrid, bimolecular fluorescence complementation, and coimmunoprecipitation assays revealed that HISTONE DEACETYLASE19 (HDA19) interacted with the HIGH-LEVEL EXPRESSION OF SUGAR-INDUCIBLE GENE2-LIKE1 (HSL1), and the zinc-finger CW [conserved Cys (C) and Trp (W) residues] domain of HSL1 was responsible for the interaction. Furthermore, we found that mutations in HDA19 resulted in the ectopic expression of seed maturation genes in seedlings, which was associated with increased levels of gene activation marks, such as Histone H3 acetylation (H3ac), Histone H4 acetylation (H4ac), and Histone H3 Lys 4 tri-methylation (H3K4me3), but decreased levels of the gene repression mark Histone H3 Lys 27 tri-methylation (H3K27me3) in the promoter and/or coding regions. In addition, elevated transcription of certain seed maturation genes was also found in the hsl1 mutant seedlings, which was also accompanied by the enrichment of gene activation marks but decreased levels of the gene repression mark. Chromatin immunoprecipitation assays showed that HDA19 could directly bind to the chromatin of the seed maturation genes. These results suggest that HDA19 and HSL1 may act together to repress seed maturation gene expression during germination. Further genetic analyses revealed that the homozygous hsl1 hda19 double mutants are embryonic lethal, suggesting that HDA19 and HSL1 may play a vital role during embryogenesis.
PECTIN METHYLESTERASE INHIBITOR6 Promotes Arabidopsis Mucilage Release by Limiting Methylesterification of Homogalacturonan in Seed Coat Epidermal Cells
Authors: Saez-Aguayo Susana , Ralet Marie-Christine , Berger Adeline , Botran Lucy , Ropartz David , Marion-Poll Annie , North Helen M.
Published: January 2013

Imbibed seeds of the Arabidopsis thaliana accession Djarly are affected in mucilage release from seed coat epidermal cells. The impaired locus was identified as a pectin methylesterase inhibitor gene, PECTIN METHYLESTERASE INHIBITOR6 (PMEI6), specifically expressed in seed coat epidermal cells at the time when mucilage polysaccharides are accumulated. This spatio-temporal regulation appears to be modulated by GLABRA2 and LEUNIG HOMOLOG/MUCILAGE MODIFIED1, as expression of PMEI6 is reduced in mutants of these transcription regulators. In pmei6, mucilage release was delayed and outer cell walls of epidermal cells did not fragment. Pectin methylesterases (PMEs) demethylate homogalacturonan (HG), and the majority of HG found in wild-type mucilage was in fact derived from outer cell wall fragments. This correlated with the absence of methylesterified HG labeling in pmei6, whereas transgenic plants expressing the PMEI6 coding sequence under the control of the 35S promoter had increased labeling of cell wall fragments. Activity tests on seeds from pmei6 and 35S:PMEI6 transgenic plants showed that PMEI6 inhibits endogenous PME activities, in agreement with reduced overall methylesterification of mucilage fractions and demucilaged seeds. Another regulator of PME activity in seed coat epidermal cells, the subtilisin-like Ser protease SBT1.7, acts on different PMEs, as a pmei6 sbt1.7 mutant showed an additive phenotype.
Methyl 2-bromo-3-(4-chlorobenzenesulfonamido)benzoate
Authors: Ghafoor Ahmad Z. , Chang Brian , King Christopher L. , Butcher Ray J. , Kulkarni Amol A.
Published: January 2013

In the crystal structure of the title compound, C14H11BrClNO4S, the molecules form inversion dimers withR22(8) motifs through pairs of N—H...O hydrogen bonds. The benzene rings are not coplanar and subtend a dihedral angle of 66.27 (8)°. The carbomethoxy group makes a dihedral angle of 75.1 (1)° with the ring to which it is attached.
Phenyl acridine-9-carboxylate
Authors: Wera Michał , Trzybiński Damian , Krzymiński Karol , Błażejowski Jerzy
Published: January 2013

The acridine ring system and the benzene ring in the title compound, C20H13NO2, are oriented at a dihedral angle of 6.4 (2)°. The carboxyl group is twisted at an angle of 83.6 (2)° relative to the acridine skeleton. The molecules in the crystal are arranged in stacks along thebaxis, with two of the acridine rings involved in multiple π–π interactions [centroid–centroid distances in the range 3.536 (2)–3.894 (2) Å]. Stacks arranged parallel are linkedviaC—H...π interactions, forming layers in theacplane that are in contact with adjacent, inversely oriented layersviaother C—H...π interactions, giving rise to double layers. The inversely oriented double layers interact dispersively. The acridine units are parallel within the parallel-oriented stacks, but inclined at an angle of 79.6 (2)° in the inversely oriented stacks.