bluuebunny/crossref_metadata_2025 huggingface dataset:
Inference of interactions in cyanobacterial–heterotrophic co-cultures via transcriptome sequencing
Authors: Beliaev Alexander S , Romine Margie F , Serres Margrethe , Bernstein Hans C , Linggi Bryan E , Markillie Lye M , Isern Nancy G , Chrisler William B , Kucek Leo A , Hill Eric A , Pinchuk Grigoriy E , Bryant Donald A , Steven Wiley H , Fredrickson Jim K , Konopka Allan
Published: April 2014

We used deep sequencing technology to identify transcriptional adaptation of the euryhaline unicellular cyanobacterium Synechococcus sp. PCC 7002 and the marine facultative aerobe Shewanella putrefaciens W3-18-1 to growth in a co-culture and infer the effect of carbon flux distributions on photoautotroph–heterotroph interactions. The overall transcriptome response of both organisms to co-cultivation was shaped by their respective physiologies and growth constraints. Carbon limitation resulted in the expansion of metabolic capacities, which was manifested through the transcriptional upregulation of transport and catabolic pathways. Although growth coupling occurred via lactate oxidation or secretion of photosynthetically fixed carbon, there was evidence of specific metabolic interactions between the two organisms. These hypothesized interactions were inferred from the excretion of specific amino acids (for example, alanine and methionine) by the cyanobacterium, which correlated with the downregulation of the corresponding biosynthetic machinery in Shewanella W3-18-1. In addition, the broad and consistent decrease of mRNA levels for many Fe-regulated Synechococcus 7002 genes during co-cultivation may indicate increased Fe availability as well as more facile and energy-efficient mechanisms for Fe acquisition by the cyanobacterium. Furthermore, evidence pointed at potentially novel interactions between oxygenic photoautotrophs and heterotrophs related to the oxidative stress response as transcriptional patterns suggested that Synechococcus 7002 rather than Shewanella W3-18-1 provided scavenging functions for reactive oxygen species under co-culture conditions. This study provides an initial insight into the complexity of photoautotrophic–heterotrophic interactions and brings new perspectives of their role in the robustness and stability of the association.
The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism
Authors: Frost Gary , Sleeth Michelle L. , Sahuri-Arisoylu Meliz , Lizarbe Blanca , Cerdan Sebastian , Brody Leigh , Anastasovska Jelena , Ghourab Samar , Hankir Mohammed , Zhang Shuai , Carling David , Swann Jonathan R. , Gibson Glenn , Viardot Alexander , Morrison Douglas , Louise Thomas E , Bell Jimmy D.
Published: April 2014

Increased intake of dietary carbohydrate that is fermented in the colon by the microbiota has been reported to decrease body weight, although the mechanism remains unclear. Here we use in vivo11C-acetate and PET-CT scanning to show that colonic acetate crosses the blood–brain barrier and is taken up by the brain. Intraperitoneal acetate results in appetite suppression and hypothalamic neuronal activation patterning. We also show that acetate administration is associated with activation of acetyl-CoA carboxylase and changes in the expression profiles of regulatory neuropeptides that favour appetite suppression. Furthermore, we demonstrate through 13C high-resolution magic-angle-spinning that 13C acetate from fermentation of 13C-labelled carbohydrate in the colon increases hypothalamic 13C acetate above baseline levels. Hypothalamic 13C acetate regionally increases the 13C labelling of the glutamate–glutamine and GABA neuroglial cycles, with hypothalamic 13C lactate reaching higher levels than the ‘remaining brain’. These observations suggest that acetate has a direct role in central appetite regulation.
Phase synchronization between collective rhythms of fully locked oscillator groups
Authors: Kawamura Yoji
Published: April 2014

A system of coupled oscillators can exhibit a rich variety of dynamical behaviors. When we investigate the dynamical properties of the system, we first analyze individual oscillators and the microscopic interactions between them. However, the structure of a coupled oscillator system is often hierarchical, so that the collective behaviors of the system cannot be fully clarified by simply analyzing each element of the system. For example, we found that two weakly interacting groups of coupled oscillators can exhibit anti-phase collective synchronization between the groups even though all microscopic interactions are in-phase coupling. This counter-intuitive phenomenon can occur even when the number of oscillators belonging to each group is only two, that is, when the total number of oscillators is only four. In this paper, we clarify the mechanism underlying this counter-intuitive phenomenon for two weakly interacting groups of two oscillators with global sinusoidal coupling.
Current-induced spin polarization on metal surfaces probed by spin-polarized positron beam
Authors: Zhang H. J. , Yamamoto S. , Fukaya Y. , Maekawa M. , Li H. , Kawasuso A. , Seki T. , Saitoh E. , Takanashi K.
Published: April 2014

Current-induced spin polarization (CISP) on the outermost surfaces of Au, Cu, Pt, Pd, Ta and W nanoscaled films were studied using a spin-polarized positron beam. The Au and Cu surfaces showed no significant CISP. In contrast, the Pt, Pd, Ta and W films exhibited large CISP (3~15% per input charge current of 105 A/cm2) and the CISP of Ta and W were opposite to those of Pt and Pd. The sign of the CISP obeys the same rule in spin Hall effect suggesting that the spin-orbit coupling is mainly responsible for the CISP. The magnitude of the CISP is explained by the Rashba-Edelstein mechanism rather than the diffusive spin Hall effect. This settles a controversy, that which of these two mechanisms dominates the large CISP on metal surfaces.
Quantum-chemical insights into mixed-valence systems: within and beyond the Robin–Day scheme
Authors: Parthey M. , Kaupp M.
Published: April 2014

The application of quantum-chemical methods to both organic and transition-metal mixed-valence systems is reviewed, with particular emphasis on how to describe correctly delocalisationvs.localisation near the borderline between Robin–Day classes II and III.
Sub-2 μm fully porous and partially porous (core–shell) stationary phases for reversed phase liquid chromatography
Authors: Borges Endler M. , Rostagno Mauricio A. , Meireles M. Angela A.
Published: April 2014

The need for increased throughput and superior performance has increased the demand for stationary phases with improved kinetic performance.
Iron-catalyzed alkylation of α-oxo ketene dithioacetals
Authors: Yang Qin , Wu Ping , Chen Jiping , Yu Zhengkun
Published: April 2014

Iron-catalyzed alkylation of α-oxo ketene dithioacetals by styrenes efficiently afforded highly functionalized tetrasubstituted olefins.
Stereoisomeric semiconducting radical cation salts of chiral bis(2-hydroxypropylthio)ethylenedithioTTF with tetrafluoroborate anions
Authors: Martin Lee , Wallis John D. , Guziak Milena A. , Oxspring Jack , Lopez Jordan R. , Nakatsuji Shin'ichi , Yamada Jun'ichi , Akutsu Hiroki
Published: April 2014

A new chiral TTF-based donor has produced enantiopure R,R and S,S radical cation salts with the tetrafluoroborate anion as well as the nearly isostructural meso/racemate mixture.
Mesocrystals as a class of multifunctional materials
Authors: Liu Yanqiong , Zhang Yu , Wang John
Published: April 2014

Mesocrystals that consist of crystallographically aligned individual building blocks and controlled level of porosity in between exhibit unique structures and multifunctional behavior.
A Ti3+:TiO2/TiF3 hybrid with enhanced visible-light photocatalytic reactivity
Authors: Meng Xiaodong , Huang Baibiao , Ma Xiangchao , Wang Zeyan , Zheng Zhaoke , Wang Junpeng , Qin Xiaoyan , Zhang Xiaoyang , Dai Ying
Published: April 2014

A Ti3+:TiO2/TiF3 hybrid contains a high concentration of Ti3+ species and exhibits enhanced absorption in the visible region.
Physicochemical properties of N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide for sodium metal battery applications
Authors: Yoon Hyungook , Zhu Haijin , Hervault Aziliz , Armand Michel , MacFarlane Douglas R. , Forsyth Maria
Published: April 2014

The physicochemical properties of a range of NaNTf2 (or NaTFSI) salt concentrations in N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (or C3mpyrFSI) ionic liquid were investigated by DSC, conductivity, cyclic voltammetry and diffusivity studies.
Direct measurements of the total rate constant of the reaction NCN + H and implications for the product branching ratio and the enthalpy of formation of NCN
Authors: Faßheber Nancy , Dammeier Johannes , Friedrichs Gernot
Published: April 2014

The high-temperature rate constant of the reaction NCN + H, a key reaction for modelling NOx formation in flames, has been directly measured for the first time.
The protective effect of the mesoporous host on the photo oxidation of fluorescent guests: a UV-Vis spectroscopy study
Authors: Miletto Ivana , Massa Annalisa , Ugazio Elena , Musso Giorgia , Caputo Giuseppe , Berlier Gloria
Published: April 2014

The inclusion of fluorescent molecules within the pores of an inorganic host system ensures an outstanding improvement of stability against photo oxidation under different experimental conditions.
Nanochemistry-derived Bi2WO6nanostructures: towards production of sustainable chemicals and fuels induced by visible light
Authors: Zhang Nan , Ciriminna Rosaria , Pagliaro Mario , Xu Yi-Jun
Published: April 2014

The advances of Bi2WO6nanostructures utilized in photocatalytic organic synthesis and fuel production under visible light are discussed and prospected.
Sulfidation of copper oxide nanoparticles and properties of resulting copper sulfide
Authors: Ma Rui , Stegemeier John , Levard Clément , Dale James G. , Noack Clinton W. , Yang Tiffany , Brown Gordon E. , Lowry Gregory V.
Published: April 2014

Sulfidation of 40 nm CuO nanoparticles in water yields poorly structured CuxSyand crystalline covellite (CuS) with increasing apparent solubility.
Non-equilibrium Dirac carrier dynamics in graphene investigated with time- and angle-resolved photoemission spectroscopy
Authors: Gierz Isabella , Link Stefan , Starke Ulrich , Cavalleri Andrea
Published: April 2014

We have used time- and angle-resolved photoemission spectroscopy (tr-ARPES) to assess the influence of many-body interactions on the Dirac carrier dynamics in graphene. From the energy-dependence of the measured scattering rates we directly determine the imaginary part of the self-energy, visualizing the existence of a relaxation bottleneck associated with electron–phonon coupling. A comparison with static line widths obtained by high-resolution ARPES indicates that the dynamics of photo-excited carriers in graphene are solely determined by the equilibrium self-energy. Furthermore, the subtle interplay of different many-body interactions in graphene may allow for carrier multiplication, where the absorption of a single photon generates more than one electron-hole pair via impact ionization. We find that, after photo-excitation, the number of carriers in the conduction band along the ΓK-direction keeps increasing for about 40 fs after the pump pulse is gone. A definite proof of carrier multiplication in graphene, however, requires a more systematic study, carefully taking into account the contribution of momentum relaxation on the measured rise time.
Non-negative matrix analysis for effective feature extraction in X-ray spectromicroscopy
Authors: Mak Rachel , Lerotic Mirna , Fleckenstein Holger , Vogt Stefan , Wild Stefan M. , Leyffer Sven , Sheynkin Yefim , Jacobsen Chris
Published: April 2014

X-Ray absorption spectromicroscopy provides rich information on the chemical organization of materials down to the nanoscale. However, interpretation of this information in studies of “natural” materials such as biological or environmental science specimens can be complicated by the complex mixtures of spectroscopically complicated materials present. We describe here the shortcomings that sometimes arise in previously-employed approaches such as cluster analysis, and we present a new approach based on non-negative matrix approximation (NNMA) analysis with both sparseness and cluster-similarity regularizations. In a preliminary study of the large-scale biochemical organization of human spermatozoa, NNMA analysis delivers results that nicely show the major features of spermatozoa with no physically erroneous negative weightings or thicknesses in the calculated image.
Anxiolytic and antidepressant like effects of natural food flavour (E)-methyl isoeugenol
Authors: Fajemiroye James Oluwagbamigbe , Galdino Pablinny Moreira , De Paula Joelma Abadia Marciano , Rocha Fagundes Fabio , Akanmu Moses A. , Vanderlinde Frederico Argollo , Zjawiony Jordan K. , Costa Elson Alves
Published: April 2014

We demonstrate anxiolytic and antidepressant like properties of (E)-methyl isoeugenol, and suggest the participation of serotonergic pathways.
Modulation of nitric oxide by flavonoids
Authors: Duarte J. , Francisco V. , Perez-Vizcaino F.
Published: April 2014

One of the main mechanisms by which dietary flavonoids are thought to influence cardiovascular disease isviaprotection of the bioactivity of the endothelium-derived nitric oxide (NO).
Synthesis of carboxylate functionalized A3B and A2B2 thiaporphyrins and their application in dye-sensitized solar cells
Authors: Mane Sandeep B. , Hung Chen-Hsiung
Published: April 2014

Thiaporphyrins were effectively applied in dye-sensitized solar cells. Among them, N3S-ECN with an ethynylphenyl linker and cyanoacrylic acid anchor, achieved the highest efficiency of 1.69%.
Using computational methods to explore improvements to Knölker's iron catalyst
Authors: Lu Xi , Zhang Yawei , Turner Nicholas , Zhang Mingtao , Li Tonglei
Published: April 2014

Some improvements were predicted for Knölker's catalyst via density functional method.
A stereoselective approach to indolizidine and pyrrolizidine alkaloids: total synthesis of (−)-lentiginosine, (−)-epi-lentiginosine and (−)-dihydroxypyrrolizidine
Authors: Kauloorkar Shruti Vandana , Jha Vishwajeet , Jogdand Ganesh , Kumar Pradeep
Published: April 2014

The total synthesis of (−)-lentiginosine, epi-1,2-lentiginosine and dihydroxypyrrolizidine is reported from an aldehyde as a starting material using organocatalysis and asymmetric dihydroxylation as key steps.
Asymmetric synthesis of tetrahydroquinolines through supramolecular organocatalysis
Authors: Ramachary Dhevalapally B. , Shruthi Kodambahalli S.
Published: April 2014

Functionalized chiral tetrahydroquinolines were synthesized through supramolecular organocatalysis using quinidine-NH-thiourea 3c/l-phenylalanine 4i followed by reductive amination from the simple substrates.
The mechanism of water–isopropanol exchange in cement pastes evidenced by NMR relaxometry
Authors: Kowalczyk Radoslaw M. , Gajewicz Agata M. , McDonald Peter J.
Published: April 2014

Distribution (by 1H NMR intensity) of water and isopropanol in as prepared (left bars) and exchanged (right bars) cement paste.
Synthesis of medicinally important quinazolines decorated with 1,4-disubstituted-1,2,3-triazoles using CuSO4·5H2O–Et3N catalytic system
Authors: Vashist Monika , Kushwaha Khushbu , Kaushik Reena , Jain Subhash C.
Published: April 2014

The direct use of Cu(ii) sulfate pentahydrate in the presence of triethylamine afforded 1,4-disubstituted-1,2,3-triazoles via 1,3-dipolar cycloaddition of terminal alkyne(s) to azide(s) at room temperature.
Synthesis of piperazine tethered 4-aminoquinoline-pyrimidine hybrids as potent antimalarial agents
Authors: Thakur Anuj , Khan Shabana I. , Rawat Diwan S.
Published: April 2014

Piperazine linked 4-aminoquinoline-pyrimidine hybrids were synthesized and evaluated for in vitro antimalarial activity against W2 and D6 strains of plasmodium falciparum.
Photothermal response of the plasmonic nanoconglomerates in films assembled by electroless plating
Authors: Lisunova Milana , Wei Xingfei , DeJarnette Drew , Forcherio Gregory T. , Berry Keith R. , Blake Phillip , Roper D. Keith
Published: April 2014

Conversion of light energy to heat by ordered gold nanostructures on a gold film has been investigated.
Electrical characterization of TiO2/CH3NH3PbI3heterojunction solar cells
Authors: Liu Wenqiang , Zhang Yang
Published: April 2014

Electrical properties of TiO2/CH3NH3PbI3heterojunction solar cells.
A transformative route to nanoporous manganese oxides of controlled oxidation states with identical textural properties
Authors: Lee Jae Hwa , Sa Young Jin , Kim Tae Kyung , Moon Hoi Ri , Joo Sang Hoon
Published: April 2014

Controlled thermal conversion of Mn-based metal–organic frameworks yielded a series of nanoporous manganese oxides with continuously tuned oxidation states.
Graphene fiber-based asymmetric micro-supercapacitors
Authors: Zheng Bingna , Huang Tieqi , Kou Liang , Zhao Xiaoli , Gopalsamy Karthikeyan , Gao Chao
Published: April 2014

Fiber-based asymmetric micro-supercapacitor (F-asym-mSC) is assembled by core–sheath graphene fiber decorated by MnO2as the positive electrode and graphene-carbon nanotubes hybrid fiber as the negative electrode. The F-asym-mSC shows the highest energy density (11.9 μWh cm−2) for fiber-based supercapacitors and paves the way to high energy density, wearable, and flexible electronic devices.
Preparation and characterization of novel water-based biodegradable polyurethane nanoparticles encapsulating superparamagnetic iron oxide and hydrophobic drugs
Authors: Chen Yan-Ping , Hsu Shan-hui
Published: April 2014

A green and novelin situmethod for the encapsulation of SPIO and hydrophobic drugs by PU NPs was developed, where drug release may be accelerated upon magnetic heating.
Hybrids based on lanthanide ions activated yttrium metal–organic frameworks: functional assembly, polymer film preparation and luminescence tuning
Authors: Duan Tian-Wei , Yan Bing
Published: April 2014

A series of novel lanthanide (Eu, Tb, Sm, Dy) doped yttrium 1,3,5-benzenetricarboxylate have been obtainedviasolvothermal method. With varied concentration of co-doped europium and terbium in yttrium 1,3,5-benzenetricarboxylate, the emitting colors of obtained materials changed under the same excitation wavelength.
Colloidal solutions of niobium trisulfide and niobium triselenide
Authors: Fedorov Vladimir E. , Artemkina Sofya B. , Grayfer Ekaterina D. , Naumov Nikolay G. , Mironov Yuri V. , Bulavchenko Alexander I. , Zaikovskii Vladimir I. , Antonova Irina V. , Komonov Alexander I. , Medvedev Maxim V.
Published: April 2014

Bulk NbS3and NbSe3were stably dispersed in a number of organic solvents to yield colloids containing thin well-crystallized nanoribbons of NbS3and NbSe3.
Structural insights into the substrate-binding mechanism for a novel chitosanase
Authors: Lyu Qianqian , Wang Song , Xu Wenhua , Han Baoqin , Liu Wanshun , Jones David N. M. , Liu Weizhi
Published: April 2014

Chitosanase is able to specifically cleave β-1,4-glycosidic bond linkages in chitosan to produce a chito-oligomer product, which has found a variety of applications in many areas, including functional food and cancer therapy. Although several structures for chitosanase have been determined, the substrate-binding mechanism for this enzyme has not been fully elucidated because of the lack of a high-resolution structure of the chitosanase–substrate complex. In the present study we show the crystal structure of a novel chitosanase OU01 from Microbacterium sp. in complex with its substrate hexa-glucosamine (GlcN)6, which belongs to the GH46 (glycoside hydrolyase 46) family in the Carbohydrate Active Enzymes database (http://www.cazy.org/). This structure allows precise determination of the substrate-binding mechanism for the first time. The chitosanase–(GlcN)6 complex structure demonstrates that, from the −2 to +1 position of the (GlcN)6 substrate, the pyranose rings form extensive interactions with the chitosanase-binding cleft. Several residues (Ser27, Tyr37, Arg45, Thr58, Asp60, His203 and Asp235) in the binding cleft are found to form important interactions required to bind the substrate. Site-directed mutagenesis of these residues showed that mutations of Y37F and H203A abolish catalytic activity. In contrast, the mutations T58A and D235A only lead to a moderate loss of catalytic activity, whereas the S27A mutation retains ~80% of the enzymatic activity. In combination with previous mutagenesis studies, these results suggest that the −2, −1 and +1 subsites play a dominant role in substrate binding and catalysis. DSF (differential scanning fluorimetry) assays confirmed that these mutations had no significant effect on protein stability. Taken together, we present the first mechanistic interpretation for the substrate (GlcN)6 binding to chitosanase, which is critical for the design of novel chitosanase used for biomass conversion.
Assessing Children’s Language Skills at a Distance: Does it Work?
Authors: Manzanares Brian , Kan Pui Fong
Published: April 2014

The purpose of this study was to explore the effects of using videoconferencing to assess children’s language skills. Participants were 6 typically developing monolingual English-speaking children, ages 3;0–5;11, from middle class families. Using a within-subjects design, the participants completed a story-retell task in both videoconferencing (VC) and face-to-face (F2F) conditions. During the task for each condition, children were presented with a story, along with a wordless book. In addition, 4 unfamiliar words were embedded within the story. Results showed that there were no significant differences in the microstructures of their narratives between F2F and VC conditions. Results also showed that children learned the target words in both conditions equally well. The findings in this study provide evidence that the VC and F2F conditions are comparable when administering the story-retell task to typically developing young children. Despite these preliminary findings, more research is needed to verify whether or not similar results would be found with young children with communication challenges.
Kinetic Magnetic Resonance Imaging of the Cervical Spine: A Review of the Literature
Authors: Lord Elizabeth L. , Alobaidan Raed , Takahashi Shinji , Cohen Jeremiah R. , Wang Christopher J. , Wang Benjamin J. , Wang Jeffrey C.
Published: April 2014

Study Design

Literature review.

Objective

The purpose of this study is to compile and review the body of literature related to kinetic magnetic resonance imaging (kMRI) of the cervical spine.

Methods

A review of literature related to kMRI was performed using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.

Results

We included 16 prospective and retrospective studies of symptomatic and asymptomatic patients who underwent kMRI of the cervical spine.

Conclusions

Data suggest that kMRI is able to provide meaningful information regarding changes in the cervical spine in both normal and pathologic segments. A prospective study comparing magnetic resonance imaging and kMRI is needed to confirm clinically utility of this technology.
Business Value through Controlled IT: Toward An Integrated Model of IT Governance Success and Its Impact
Authors: Buchwald Arne , Urbach Nils , Ahlemann Frederik
Published: April 2014

Owing to increasing regulatory pressure and the need for aligned information technology (IT) decisions at the interface of business and IT, IT governance (ITG) has become important in both academia and practice. However, knowledge of integrating the determinants and consequences of ITG success remains scarce. Although some studies investigate individual aspects of ITG success and its impact, none combine these factors into a comprehensive and integrated model that would lead to a more complete understanding of the ITG concept. To address this gap, our research aims at understanding what factors influence and result from successful ITG, and at determining how they can be translated into a model to explain ITG success and the impact thereof. Therefore, we conducted interviews with 28 IT decision makers in 19 multinational organizations headquartered in Europe. Our study synthesizes the fragmented previous research, provides new empirical insights gathered on the basis of a clear ITG conceptualization, and suggests three innovative constructs heretofore not related to ITG. Moreover, we elucidate in a holistic model the factors that make ITG successful, how ITG contributes to an IT organization's success, and how it eventually unfolds throughout the overall organization. The resulting model allows organizational decision makers to develop an effective ITG implementation and to explain the implications of successful ITG, thus providing a justification for the respective investments.
Sampling saddle points on a free energy surface
Authors: Samanta Amit , Chen Ming , Yu Tang-Qing , Tuckerman Mark , E Weinan
Published: April 2014

Many problems in biology, chemistry, and materials science require knowledge of saddle points on free energy surfaces. These saddle points act as transition states and are the bottlenecks for transitions of the system between different metastable states. For simple systems in which the free energy depends on a few variables, the free energy surface can be precomputed, and saddle points can then be found using existing techniques. For complex systems, where the free energy depends on many degrees of freedom, this is not feasible. In this paper, we develop an algorithm for finding the saddle points on a high-dimensional free energy surface “on-the-fly” without requiring a priori knowledge the free energy function itself. This is done by using the general strategy of the heterogeneous multi-scale method by applying a macro-scale solver, here the gentlest ascent dynamics algorithm, with the needed force and Hessian values computed on-the-fly using a micro-scale model such as molecular dynamics. The algorithm is capable of dealing with problems involving many coarse-grained variables. The utility of the algorithm is illustrated by studying the saddle points associated with (a) the isomerization transition of the alanine dipeptide using two coarse-grained variables, specifically the Ramachandran dihedral angles, and (b) the beta-hairpin structure of the alanine decamer using 20 coarse-grained variables, specifically the full set of Ramachandran angle pairs associated with each residue. For the alanine decamer, we obtain a detailed network showing the connectivity of the minima obtained and the saddle-point structures that connect them, which provides a way to visualize the gross features of the high-dimensional surface.
An experimental technique of split Hopkinson pressure bar using fiber micro-displacement interferometer system for any reflector
Authors: Fu H. , Tang X. R. , Li J. L. , Tan D. W.
Published: April 2014

A novel non-contact measurement technique had been developed for the mechanical properties of materials in Split Hopkinson Pressure Bars (SHPB). Instead of the traditional strain gages mounted on the surfaces of bars, two shutters were mounted on the end of bars to directly measure interfacial velocity using Fiber Micro-Displacement Interferometer System for Any Reflector. Using the new technique, the integrated stress-strain responses could be determined. The experimental technique was validated by SHPB test simulation. The technique had been used to investigate the dynamic response of a brittle explosive material. The results showed that the new experimental technique could be applied to the dynamic behavior in SHPB test.
Ultraviolet digital image correlation (UV-DIC) for high temperature applications
Authors: Berke Ryan B. , Lambros John
Published: April 2014

A method is presented for extending two-dimensional digital image correlation (DIC) to a higher range of temperatures by using ultraviolet (UV) lights and UV optics to minimize the light emitted by specimens at those temperatures. The method, which we refer to as UV-DIC, is compared against DIC using unfiltered white light and DIC using filtered blue light which in the past have been used for high temperature applications. It is shown that at low temperatures for which sample glowing is not an issue all three methods produce the same results. At higher temperatures in our experiments, the unfiltered white light method showed significant glowing between 500 and 600 °C and the blue light between 800 and 900 °C, while the UV-DIC remained minimally affected until the material began nearing its melting point (about 1260 °C). The three methods were then used to obtain the coefficient of thermal expansion as a function of temperature for the nickel superalloy Hastelloy-X. All three methods give similar coefficients at temperatures below which glowing becomes significant, with the values also being comparable to the manufacturers specifications. Similar results were also seen in uniaxial tension tests.
High resolution jet-cooled infrared absorption spectra of the formic acid dimer: A reinvestigation of the C–O stretch region
Authors: Goroya Kusse G. , Zhu Yu , Sun Ping , Duan Chuanxi
Published: April 2014

The vibration-rotation-tunneling absorption spectra of the formic acid dimer (HCOOH)2 have been measured in the C–O stretch region at 1215–1240 cm−1 using a rapid-scan tunable diode laser spectrometer in conjunction with a slit supersonic expansion. The ν5 fundamental band of the HCOOH monomer is identified and the perturbed band-center is 1220.83329(10) cm−1. Three vibrational bands centered at 1219.71, 1225.35, and 1233.95 cm−1 are assigned to the two combination bands and the ν22 fundamental band of (HCOOH)2 unambiguously. The transition frequencies of these three vibrational bands are fitted together using a standard Watson A-reduced Hamiltonian, yielding precise rotational and centrifugal distortion constants for each tunneling level in the ground and excited vibrational states. The fitting results of the vibrational band centered at 1225.35 cm−1 are in good agreement with a previous high resolution study [M. Ortlieb and M. Havenith, J. Phys. Chem. A. 111, 7355 (2007)]. The tunneling splittings in the vibrationally excited states are −0.00304(16), −0.01023(11), and −0.00318(12) cm−1, respectively, where the minus indicates that the upper tunneling component lies energetically below the lower tunneling component. A three-state deperturbation analysis using the Fermi coupling constants obtained from a previous vibrational analysis [F. Ito, Chem. Phys. Lett. 447, 202 (2007)] fails to get the normal order of the tunneling levels for all the three excited vibrational states simultaneously.
Lanthanide contraction effect on crystal structures, magnetic, and dielectric properties in ordered double perovskites LnPbCoSbO6 (Ln = La, Pr, Nd)
Authors: Han L. , Bai Y. J. , Meng F. Z. , Liu X. J. , Yao C. G. , Meng J. L. , Liang Q. S. , Wu X. J. , Meng J.
Published: April 2014

The crystal structures, magnetic, and dielectric properties for the ordered double perovskites LnPbCoSbO6 (Ln = La, Pr, Nd) have been investigated. The crystal structure has been solved by Rietveld refinements of X-ray diffraction data in the monoclinic space group P21/n (No. 14). The Co2+ and Sb5+ ions are almost fully ordered over the B-site, and the octahedral framework displays significant tilting distortion according to the Glazer's tilt system a–a–c+. As the result of lanthanide contraction from La3+ to Nd3+, the B-site sublattice distortions become stronger accompanying with the reduction of the tolerance factor and coordination number. The magnetization measurements show an antiferromagnetic ordering with large effective magnetic moments (μeff) suggesting that the orbital component is significant. The maximum values of isothermal magnetization increase with the decrease in radii of rare earth ions, which is attributed to the weakening of antiferromagnetic interaction via Co2+–O–Sb5+–O–Co2+ paths. The dielectric constants present frequency dependence and monotonically decrease with the ionic radii reduction from La3+ to Nd3+ due to the suppression of electron transfer. These results indicate that the magnetic and dielectric properties can be tuned by controlling the degree of lattice distortion, which is realized by introducing different Ln3+ ions at the A-site.
Formation of diatomic molecular radicals in reactive nitrogen-carbon plasma generated by electron cyclotron resonance discharge and pulsed laser ablation
Authors: Liang Peipei , Li Yanli , You Qinghu , Cai Hua , Yang Xu , Sun Jian , Xu Ning , Wu Jiada
Published: April 2014

The reactive nitrogen-carbon plasma generated by electron cyclotron resonance (ECR) microwave discharge of N2 gas and pulsed laser ablation of a graphite target was characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy with space resolution for a study of gas-phase reactions and molecular radical formation in the plasma. The plasma exhibits very high reactivity compared with the plasma generated solely by ECR discharge or by pulsed laser ablation and contains highly excited species originally present in the ambient gaseous environment and directly ablated from the target as well as formed as the products of gas-phase reactions occurring in the plasma. The space distribution and the time evolution of the plasma emission give an access to the gas-phase reactions for the formation of C2 and CN radicals, revealing that C2 radicals are formed mainly in the region near the target while CN radicals can be formed in a much larger region not only in the vicinity of the target, but especially in the region near a substrate far away from the target.
Poincaré recurrence statistics as an indicator of chaos synchronization
Authors: Boev Yaroslav I. , Vadivasova Tatiana E. , Anishchenko Vadim S.
Published: April 2014

The dynamics of the autonomous and non-autonomous Rössler system is studied using the Poincaré recurrence time statistics. It is shown that the probability distribution density of Poincaré recurrences represents a set of equidistant peaks with the distance that is equal to the oscillation period and the envelope obeys an exponential distribution. The dimension of the spatially uniform Rössler attractor is estimated using Poincaré recurrence times. The mean Poincaré recurrence time in the non-autonomous Rössler system is locked by the external frequency, and this enables us to detect the effect of phase-frequency synchronization.
Porous silicon formation during Au-catalyzed etching
Authors: Algasinger Michael , Bernt Maximilian , Koynov Svetoslav , Stutzmann Martin
Published: April 2014

The formation of “black” nano-textured Si during the Au-catalyzed wet-chemical etch process was investigated with respect to photovoltaic applications. Cross-sectional scanning electron microscopy (SEM) images recorded at different stages of the etch process exhibit an evolution of a two-layer structure, consisting of cone-like Si hillocks covered with a nano-porous Si (np-Si) layer. Optical measurements confirm the presence of a np-Si phase which appears after the first ∼10 s of the etch process and continuously increases with the etch time. Furthermore, the etch process was investigated on Si substrates with different doping levels (∼0.01–100 Ω cm). SEM images show a transition from the two-layer morphology to a structure consisting entirely of np-Si for higher doping levels (<0.1 Ω cm). The experimental results are discussed on the basis of the model of a local electrochemical etch process. A better understanding of the metal-catalyzed etch process facilitates the fabrication of “black” Si on various Si substrates, which is of significant interest for photovoltaic applications.
Theoretical analysis on low frequency magneto-mechano-electric coupling behavior in piezo-unimorph/magnet composite
Authors: Liu Guoxi , Ci Penghong , Dong Shuxiang
Published: April 2014

The low frequency magneto-mechano-electric (MME) coupling behavior in the piezo-unimorph/magnet composites has been investigated. A theoretical model on the low frequency MME coupling behaviors for the piezo-unimorph/magnet composite was proposed. The experimental results coincided with the corresponding theoretical prediction and proved the validity of the theoretical model. Based on the theoretical model, the dependencies of the magnetoelectric voltage coefficients on the geometrical parameters of the piezo-unimorph/magnet composite were numerically calculated. The results show that there are optimal geometrical parameters of the piezo-unimorph/magnet composite for achieving maximum ME voltage coefficients. This research gives a theoretical basis to understand the low frequency MME coupling behaviors in the piezo-unimorph/magnet composite and provides a theoretical approach for optimal design of MME devices based on this configuration.
Alterations in stem sugar content and metabolism in sorghum genotypes subjected to drought stress
Authors: Qazi Hilal A. , Srinivasa Rao Pinnamaneni , Kashikar Akanksha , Suprasanna Penna , Bhargava Sujata
Published: April 2014

Changes in stem sugar concentrations due to drought stress at the early reproductive stage were studied in seven sorghum (Sorghum bicolor (L.) Moench) genotypes that differ in their stem sugar storage ability. Total sap sugar concentration increased in most genotypes. ANOVA showed a significant contribution of genotype and treatment to the variation in sugar levels. Two genotypes showed little variation in total sugar levels at the fifth internode from the peduncle and five genotypes showed significant increases in total sugar levels under drought; these groups were used to compare sugar metabolism. Drought led to a decrease in catabolic sucrose synthase activity in both groups. Invertase activities increased significantly in two genotypes and correlated with the increase in reducing sugar concentrations under drought. Stem sugar hydrolysis probably had a role in osmotic adjustment under drought and correlated with retention of sap volume. However, the activities of sugar-metabolising enzymes did not correlate with their gene expression levels. After resuming irrigation, grain yields, stalk yields and juice volume at physiological maturity were lower in plants recovering from drought stress compared with the controls. In some genotypes, there were similar losses in grain yields and stem sugars due to drought, indicating photoassimilate source limitation; in other genotypes, grain yield losses were less than stem sugar losses in drought-exposed plants compared with the controls, suggesting mobilisation of sugars from the storage internodes to the developing panicle. Accumulation of stem sugars appears to be an adaptive strategy against drought stress in some sorghum genotypes.
Amending soil with sludge, manure, humic acid, orthophosphate and phytic acid: effects on aggregate stability
Authors: Mamedov A. I. , Bar-Yosef B. , Levkovich I. , Rosenberg R. , Silber A. , Fine P. , Levy G. J.
Published: April 2014

Recycling of organic wastes via their incorporation in cultivated lands is known to alter soil structural stability. Aggregate stability tests are commonly used to express quantitatively the susceptibility of soil structural stability to deformation. The objective of this study was to investigate the effects of biosolids addition, namely composted manure (MC) and activated sludge (AS), and spiking of the soils with orthophosphate (OP), phytic acid (PA) or humic acid (HA), on soil aggregate stability of semi-arid loamy sand, loam and clay soils before and after subjecting the soils to six rain storms (each 30 mm rain with a break of 3–4 days). Aggregate stability was determined from water-retention curves at high matric potential. The effects of the applied amendments on pre- and post-rain aggregate stability were inconsistent and soil-dependent. For the pre-rain state, all of the tested amendments improved aggregate stability relative to the control. For the post-rain condition, aggregate stability was lower in the MC, OP and PA treatments and higher in the AS and HA treatments than in the control. The coarse-textured loam and loamy sand soils were more affected by the soil amendments than the clay soil. For the pre-rain state, addition of organic matter significantly improved macro-porosity and hence the stability of apparent macro-aggregate (>250 μm). Our results indicate a possible advantage for separation of aggregates into macro- and micro-aggregates for more precise evaluation and understanding of the effects organic amendments might have on aggregate stability.
Cattle ranching intensification in Brazil can reduce global greenhouse gas emissions by sparing land from deforestation
Authors: Cohn Avery S. , Mosnier Aline , Havlík Petr , Valin Hugo , Herrero Mario , Schmid Erwin , O’Hare Michael , Obersteiner Michael
Published: April 2014

Significance

Could the intensification of pasture-based cattle ranching allow Brazil to protect its forests and reduce its greenhouse gas (GHG) emissions while increasing its agricultural production? Would these benefits be substantially undermined by increased deforestation and GHGs triggered abroad? We model two policies for increasing cattle ranching productivity in Brazil: a tax on conventional pasture and a subsidy for semi-intensive pasture. Either policy could considerably mitigate global GHGs by limiting future deforestation in Brazil. The GHG benefits would be roughly ten times greater than the emissions triggered by policies stemming from (
i
) increased cattle production abroad (under the tax) and (
ii
) increased beef consumption (under the subsidy). Agricultural intensification policies may help emerging economies to balance agricultural development and forest protection.
Controllability in protein interaction networks
Authors: Wuchty Stefan
Published: April 2014

Significance

In human and yeast protein interaction datasets we determined minimum dominating sets (MDSets), proteins that play a role in the control of the underlying interaction webs. Such proteins are defined as optimized subsets from where each remaining protein can be immediately reached. Notably, MDSet proteins were enriched with cancer-related and virus-targeted genes. Furthermore, MDSet proteins have a higher impact on network resilience than hub proteins. Indicating their relevance for the controllability of biological networks, we also found a strong involvement in bottleneck interactions, regulatory and phosphorylation events as well as genetic interactions.
Capping protein regulatory cycle driven by CARMIL and V-1 may promote actin network assembly at protruding edges
Authors: Fujiwara Ikuko , Remmert Kirsten , Piszczek Grzegorz , Hammer John A.
Published: April 2014

Significance

Assembly of actin filaments near the plasma membrane drives extension of the cell edge as it migrates. Cells recruit a protein machine called the Arp2/3 complex to the leading edge to initiate actin filament branches that grow and push on the membrane. Equally important, capping protein (CP) binds to and terminates polymerization of the fast-growing end of the filament. Like other aspects of actin assembly, CP is subject to regulation. Specifically, the protein V-1/myotrophin inactivates CP, while capping protein Arp2/3 myosin I linker (CARMIL) proteins moderately inhibit CP. We describe how CARMIL and V-1 cooperate in a cycle of reactions to regulate CP and promote assembly of the actin network by the Arp2/3 complex.
Thioredoxin-related protein of 14 kDa is an efficient L-cystine reductase and S-denitrosylase
Authors: Pader Irina , Sengupta Rajib , Cebula Marcus , Xu Jianqiang , Lundberg Jon O. , Holmgren Arne , Johansson Katarina , Arnér Elias S. J.
Published: April 2014

Significance

Several functions in cells require reductive processes, i.e., the enzymatic catalysis of a transfer of electrons to specific cellular substrates. One major reductive system in the cytosol of human cells depends upon thioredoxin 1 (Trx1), which in turn is kept reduced by thioredoxin reductase 1 (TrxR1) using NADPH. In the present study it is shown that another protein in addition to Trx1, called thioredoxin-related protein of 14 kDa (TRP14), is highly efficient together with TrxR1 in catalyzing reduction of L-cystine or nitric oxide-derivatized cysteine residues. It is also shown that TRP14, in contrast to Trx1, is resistant to inactivation by hydrogen peroxide. These findings reveal that several TrxR1-dependent functions in cells may not be propelled solely by Trx1, but instead relate to activities of TRP14.
Noise differentially impacts phoneme representations in the auditory and speech motor systems
Authors: Du Yi , Buchsbaum Bradley R. , Grady Cheryl L. , Alain Claude
Published: April 2014

Significance

Contentious debate remains regarding the role of the redundant motor activation during speech perception. In this functional MRI study, multivariate pattern analysis revealed stronger multivoxel phoneme discrimination in speech motor regions than auditory cortices when the speech phonemes were moderately degraded by noise. Our findings provide neuroimaging evidence for the sensorimotor integration account. Preserved phoneme discrimination in speech motor areas may compensate for loss of specificity in noise-impoverished speech representations, which aids speech perception under adverse listening conditions.
Electrostatics, hydration, and proton transfer dynamics in the membrane domain of respiratory complex I
Authors: Kaila Ville R. I. , Wikström Mårten , Hummer Gerhard
Published: April 2014

Significance

Using large-scale classical and quantum simulations, we elucidate key aspects of the molecular function of complex I, a protein central to biological energy conversion. Complex I serves as the primary electron entry point into the mitochondrial and bacterial respiratory chains and operates as a redox-coupled proton pump. Our simulations suggest that transient water chains establish highly efficient pathways for proton transfer. Our findings form a basis for understanding long-range energy conversion in complex I, and mechanistic similarities to other redox-driven proton-pumps, such as cytochrome
c
oxidase and bacteriorhodopsin.
Third-party punishment increases cooperation in children through (misaligned) expectations and conditional cooperation
Authors: Lergetporer Philipp , Angerer Silvia , Glätzle-Rützler Daniela , Sutter Matthias
Published: April 2014

Significance

Cooperation among humans depends upon the willingness of others to take costly action to enforce the social norm to cooperate. Such behavior is often coined third-party punishment. Here we show that third-party punishment is already effective as means to increase cooperation in children. Most importantly, we identify why this is the case. First, children expect (mistakenly) third parties to punish quite often and therefore they become more cooperative. Second, the presence of third parties lets children become (rightfully) more optimistic about the cooperation levels of the interaction partner in a simple prisoner’s dilemma game. As a reaction to more optimistic expectations, children cooperate more themselves. The experiment has been run with about 1,100 children aged 7 to 11 y.
CCR5/CD4/CXCR4 oligomerization prevents HIV-1 gp120IIIBbinding to the cell surface
Authors: Martínez-Muñoz Laura , Barroso Rubén , Dyrhaug Sunniva Y. , Navarro Gemma , Lucas Pilar , Soriano Silvia F. , Vega Beatriz , Costas Coloma , Muñoz-Fernández M. Ángeles , Santiago César , Frade José Miguel Rodríguez , Franco Rafael , Mellado Mario
Published: April 2014

Significance

HIV-1 enters host cells via CD4 and the coreceptors CXCR4 or CCR5. Most HIV-1 variants isolated from newly infected individuals use CCR5 (R5 strains) and infect Th1 cells, among other cell types. In ∼50% of patients, R5 strains shift to X4 strains (which use CXCR4) and infect mainly Th2 cells, leading to poor prognosis and rapid disease progression. In Th2 cells, CD4 and CXCR4 levels resemble those of Th1 cells, but they express little CCR5. We report that CCR5 expression in CD4+T cells reduced X4 strain cell entry and infection; the molecular mechanism involves CD4/CXCR4/CCR5 oligomer formation. CCR5 expression altered CD4/CXCR4 heterodimer conformation, blocking virus binding. Oligomeric complexes should thus be considered a target for reducing HIV-1 binding and infection.