bluuebunny/crossref_metadata_2025 huggingface dataset:
Erfahrungen des Pilotprojektes „Umweltmedizinisches Beratungsnetz“ des Vereins Ärztinnen und Ärzte für Umweltschutz (AefU)
Authors: Steiner Edith , Aufdereggen Bernhard , Bhend Hansjörg , Gilli Yvonne , Kälin Peter , Semadeni Cornelia
Published: December 2013

Seit 2008 betreiben die Ärztinnen und Ärzte für Umweltschutz eine kleine umweltmedizinische Beratungsstruktur mit einer zentralen Koordinations- und Beratungsstelle und einem Netzwerk von umweltmedizinisch interessierten Grundversorgern*, welche in ihren Praxen nach einem standardisierten Protokoll umweltmedizinische Abklärungen und Beratungen durchführen. Bei Bedarf werden Umweltfachpersonen beigezogen und Hausuntersuchungen durchgeführt. Eine Begleitstudie stellt fest, dass das in den Praxisalltag integrierte Modell praktikabel ist und einem Bedarf entspricht. Das Abklärungsangebot wird von den Patienten als hilfreich erlebt. Die interdisziplinäre Zusammenarbeit mit Umweltfachpersonen hat sich bewährt. Ziel der Abklärung ist es, gängige Krankheiten zu erkennen bzw. auszuschließen und zu analysieren, welche Rolle die vermutete Umweltbelastung bei den beklagten Beschwerden spielt, um individuell Lösungswege aufzeigen zu können. Auch bei gängigen medizinischen/psychiatrischen Erkrankungen können sich Umwelteinflüsse ungünstig auf den Krankheitsverlauf auswirken. Hauptinstrument der Abklärung ist eine ausführliche medizinische und psychosoziale Anamnese mit der Besonderheit einer zusätzlichen Umweltanamnese mit systematischem Umweltfragebogen und umweltmedizinischen Schlüsselfragen. Die enge Zusammenarbeit mit dem Hausarzt ist zentral. Abklärungsschritte können verschlankt werden und Beratungsvorschläge können in das ganzheitliche Behandlungskonzept des Hausarztes eingebettet werden. Der Hausarzt spielt auch eine wichtige Rolle in der Vermittlung von Prävention und Vorsorge vor schädlichen und potentiell schädlichen Umwelteinflüssen. Gerne stellen wir – soweit wir dies können – Hausärzten unsere praxisnahen umweltbezogenen Fachkenntnisse zur Verfügung. Es ist uns ein Anliegen, dass Umweltmedizin ein fester Bestandteil der Grundversorgung wird. Wir hoffen, dass die Erfahrungen unseres Projekts hierzu einen Beitrag leisten können.
Evaluation pädiatrischer Advanced Practice Nurses: Qualität und Nutzen für die Schweiz?
Authors: Waldboth Veronika , Schlüer Anna-Barbara , Müller-Staub Maria
Published: December 2013

Die Betreuung von chronisch kranken Kindern und Jugendlichen mit multiplen Einschränkungen ist komplexer geworden und stellt Gesundheitseinrichtungen und Fachpersonen vor Herausforderungen. Neue Versorgungsmodelle wie die Implementierung von Advanced Practice Nursing sind angemessen, um auch zukünftig qualitativ hochstehende Versorgung zu gewährleisten. Im Kinderspital Zürich sichern Advanced Practice Nurses (APNs) die komplexe Betreuung der betroffenen Familien. Ziel dieser Studie ist, die Tätigkeiten der APNs Kontinenz und Wundpflege aus interdisziplinärer Sicht auf ihre Qualität und ihren Nutzen zu untersuchen. Einem Mixed Method-Ansatz folgend wurden Handlungen und Nutzen der APNs anhand von zehn qualitativen Interviews und einer parallelen Fragebogenerhebung (N = 96) evaluiert. Die Resultate zeigen die Umsetzung zentraler APN-Kompetenzen und weisen eine hohe Qualität der Tätigkeiten aus. Der Nutzen umfasst positive Auswirkungen auf die betroffenen Kinder und Familien und das interdisziplinäre Fachpersonal. Eine professionelle Wundversorgung und das Erlangen von Kontinenz wurden als Effekte identifiziert.
Glutamine‐driven oxidative phosphorylation is a major ATP source in transformed mammalian cells in both normoxia and hypoxia
Authors: Fan Jing , Kamphorst Jurre J , Mathew Robin , Chung Michelle K , White Eileen , Shlomi Tomer , Rabinowitz Joshua D
Published: December 2013

Mammalian cells can generate ATP via glycolysis or mitochondrial respiration. Oncogene activation and hypoxia promote glycolysis and lactate secretion. The significance of these metabolic changes to ATP production remains however ill defined. Here, we integrate LC‐MS‐based isotope tracer studies with oxygen uptake measurements in a quantitative redox‐balanced metabolic flux model of mammalian cellular metabolism. We then apply this approach to assess the impact of Ras and Akt activation and hypoxia on energy metabolism. Both oncogene activation and hypoxia induce roughly a twofold increase in glycolytic flux. Ras activation and hypoxia also strongly decrease glucose oxidation. Oxidative phosphorylation, powered substantially by glutamine‐driven TCA turning, however, persists and accounts for the majority of ATP production. Consistent with this, in all cases, pharmacological inhibition of oxidative phosphorylation markedly reduces energy charge, and glutamine but not glucose removal markedly lowers oxygen uptake. Thus, glutamine‐driven oxidative phosphorylation is a major means of ATP production even in hypoxic cancer cells.
Evidence of the two surface states of (Bi0.53Sb0.47)2Te3 films grown by van der Waals epitaxy
Authors: He Liang , Kou Xufeng , Lang Murong , Choi Eun Sang , Jiang Ying , Nie Tianxiao , Jiang Wanjun , Fan Yabin , Wang Yong , Xiu Faxian , Wang Kang L.
Published: December 2013

The discovery of topological insulators (TIs) has led to numerous exciting opportunities for studying topological states of quantum physics and for exploring spintronic applications due to the new physics arising from their robust metallic surface states. Here, we report the high-quality topological insulator (BixSb1−x)2Te3 thin films using a single van der Waals GaSe buffer layer. As a result, ultra-low surface carrier density of 1.3 × 1012 cm−2 and a high Hall mobility of 3100 cm2/Vs have been achieved for (Bi0.53Sb0.47)2Te3. The high-quality films enable us to observe quantum oscillations associated with the top and bottom surface states and to manipulate the Dirac electrons and bulk holes' conduction properties. The observation of the two surface states may lead to a path towards the implementation of TIs in spintronics.
l-Cysteine/glycine composite film modified glassy carbon electrode as an enhanced sensing platform for catechol determination
Authors: He Jiahong , Xing Shaohua , Qiu Ri , Song Zhongrong , Zhang Shengtao
Published: December 2013

Voltammetric sensor based on a glassy carbon electrode modified with l-cysteine/glycine composite film for the quantitative detection of catechol.
Bi-aryl rotation in phenyl-dihydroimidazoquinoline catalysts for kinetic resolution of arylalkyl carbinols
Authors: Wang Zheng , Ye Jinjin , Wu Rui , Liu Yang-Zi , Fossey John S. , Cheng Jiagao , Deng Wei-Ping
Published: December 2013

Chiral nucleophilic catalysts, 6-aryl-phenyl-dihydroimidazoquinolines (PIQs), were designed, synthesised and applied to the kinetic resolution of arylalkyl carbinols with very high selectivity (S) factors (up to 530).
Assessing the surface modifications following the mechanochemical preparation of a Ag/Al2O3 selective catalytic reduction catalyst
Authors: Ralphs Kathryn , D'Agostino Carmine , Burch Robbie , Chansai Sarayute , Gladden Lynn F. , Hardacre Christopher , James Stuart L. , Mitchell Jonathan , Taylor Sarah F. R.
Published: December 2013

Surface modifications of Ag catalysts prepared using mechanochemistry and wet-impregnation.
cis-Urocanic acid as a potential nickel(ii) binding molecule in the human skin
Authors: Wezynfeld Nina Ewa , Goch Wojciech , Bal Wojciech , Frączyk Tomasz
Published: December 2013

cis-Urocanic acid, a component of human skin, is an efficient ligand for allergenic Ni2+ ions, forming high spin complexes.
Regioselective prenylation of bromocarbazoles by palladium(0)-catalysed cross coupling – synthesis of O-methylsiamenol, O-methylmicromeline and carquinostatin A
Authors: Thomas Claudia , Kataeva Olga , Schmidt Arndt W. , Knölker Hans-Joachim
Published: December 2013

We describe the regioselective prenylation of 3-bromo-carbazole by Pd(0)-catalysed cross coupling with a prenylstannane or a prenylboronate. The procedure is applied to the synthesis of bioactive carbazole alkaloids.
Development of MnO2/porous carbon microspheres with a partially graphitic structure for high performance supercapacitor electrodes
Authors: Liu Mingxian , Gan Lihua , Xiong Wei , Xu Zijie , Zhu Dazhang , Chen Longwu
Published: December 2013

MnO2/porous carbon microspheres with a partially graphitic structure were designed and synthesized for high performance supercapacitor electrode materials.
Defect formation by pristine indenter at the initial stage of nanoindentation
Authors: Chen I-Hsien , Hsiao Chun-I , Behera Rakesh K. , Hsu Wen-Dung
Published: December 2013

Nano-indentation is a sophisticated method to characterize mechanical properties of materials. This method samples a very small amount of material during each indentation. Therefore, this method is extremely useful to measure mechanical properties of nano-materials. The measurements using nanoindentation is very sensitive to the surface topology of the indenter and the indenting surfaces. The mechanisms involved in the entire process of nanoindentation require an atomic level understanding of the interplay between the indenter and the substrate. In this paper, we have used atomistic simulation methods with empirical potentials to investigate the effect of various types of pristine indenter on the defect nucleation and growth. Using molecular dynamics simulations, we have predicted the load-depth curve for conical, vickers, and sperical tip. The results are analyzed based on the coherency between the indenter tip and substrate surface for a fixed depth of 20 Å. The depth of defect nucleation and growth is observed to be dependent on the tip geometry. A tip with larger apex angle nucleates defects at a shallower depth. However, the type of defect generated is dependent on the crystalline orientation of the tip and substrate. For coherent systems, prismatic loops were generated, which released into the substrate along the close-packed directions with continued indentation. For incoherent systems, pyramidal shaped dislocation junctions formed in the FCC systems and disordered atomic clusters formed in the BCC systems. These defect nucleation and growth process provide the atomistic mechanisms responsible for the observed load-depth response during nanoindentation.
Quasi-steady carbon plasma source for neutral beam injector
Authors: Koguchi H. , Sakakita H. , Kiyama S. , Shimada T. , Sato Y. , Hirano Y.
Published: December 2013

Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.
Random vs realistic amorphous carbon models for high resolution microscopy and electron diffraction
Authors: Ricolleau C. , Le Bouar Y. , Amara H. , Landon-Cardinal O. , Alloyeau D.
Published: December 2013

Amorphous carbon and amorphous materials in general are of particular importance for high resolution electron microscopy, either for bulk materials, generally covered with an amorphous layer when prepared by ion milling techniques, or for nanoscale objects deposited on amorphous substrates. In order to quantify the information of the high resolution images at the atomic scale, a structural modeling of the sample is necessary prior to the calculation of the electron wave function propagation. It is thus essential to be able to reproduce the carbon structure as close as possible to the real one. The approach we propose here is to simulate a realistic carbon from an energetic model based on the tight-binding approximation in order to reproduce the important structural properties of amorphous carbon. At first, we compare this carbon with the carbon obtained by randomly generating the carbon atom positions. In both cases, we discuss the limit thickness of the phase object approximation. In a second step, we show the influence of both carbons models on (i) the contrast of Cu, Ag, and Au single atoms deposited on carbon and (ii) the determination of the long-range order parameter in CoPt bimetallic nanoalloys.
Adsorption calorimetry during metal vapor deposition on single crystal surfaces: Increased flux, reduced optical radiation, and real-time flux and reflectivity measurements
Authors: Sellers Jason R. V. , James Trevor E. , Hemmingson Stephanie L. , Farmer Jason A. , Campbell Charles T.
Published: December 2013

Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ∼18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates.
Non-ideal operating conditions of the ion source prototype for the ITER neutral beam injector due to thermal deformation of the support structure
Authors: Sartori E. , Pavei M. , Marcuzzi D. , Zaccaria P.
Published: December 2013

The beam formation and acceleration of the ITER neutral beam injector will be studied in the full-scale ion source, Source for Production of Ions of Deuterium Extracted from a RF plasma (SPIDER). It will be able to sustain 40 A deuterium ion beam during 1-h pulses. The operating conditions of its multi-aperture electrodes will diverge from ideality, as a consequence of inhomogeneous heating and thermally induced deformations in the support structure of the extraction and acceleration grids, which operate at different temperatures. Meeting the requirements on the aperture alignment and distance between the grids with such a large number of apertures (1280) and the huge support structures constitute a challenge. Examination of the structure thermal deformation in transient and steady conditions has been carried out, evaluating their effect on the beam performance: the paper describes the analyses and the solutions proposed to mitigate detrimental effects.
Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring
Authors: Kumar Pradeep , Ghodke A. D. , Karnewar A. K. , Holikatti A. C. , Yadav S. , Puntambekar T. A. , Singh G. , Singh P.
Published: December 2013

In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.
Solvent effects on the ultrafast nonradiative deactivation mechanisms of thymine in aqueous solution: Excited-state QM/MM molecular dynamics simulations
Authors: Nakayama Akira , Arai Gaku , Yamazaki Shohei , Taketsugu Tetsuya
Published: December 2013

On-the-fly excited-state quantum mechanics/molecular mechanics molecular dynamics (QM/MM-MD) simulations of thymine in aqueous solution are performed to investigate the role of solvent water molecules on the nonradiative deactivation process. The complete active space second-order perturbation theory (CASPT2) method is employed for a thymine molecule as the QM part in order to provide a reliable description of the excited-state potential energies. It is found that, in addition to the previously reported deactivation pathway involving the twisting of the C-C double bond in the pyrimidine ring, another efficient deactivation pathway leading to conical intersections that accompanies the out-of-plane displacement of the carbonyl group is observed in aqueous solution. Decay through this pathway is not observed in the gas phase simulations, and our analysis indicates that the hydrogen bonds with solvent water molecules play a key role in stabilizing the potential energies of thymine in this additional decay pathway.
An improved fragment-based quantum mechanical method for calculation of electrostatic solvation energy of proteins
Authors: Jia Xiangyu , Wang Xianwei , Liu Jinfeng , Zhang John Z. H. , Mei Ye , He Xiao
Published: December 2013

An efficient approach that combines the electrostatically embedded generalized molecular fractionation with conjugate caps (EE-GMFCC) method with conductor-like polarizable continuum model (CPCM), termed EE-GMFCC-CPCM, is developed for ab initio calculation of the electrostatic solvation energy of proteins. Compared with the previous MFCC-CPCM study [Y. Mei, C. G. Ji, and J. Z. H. Zhang, J. Chem. Phys. 125, 094906 (2006)], quantum mechanical (QM) calculation is applied to deal with short-range non-neighboring interactions replacing the classical treatment. Numerical studies are carried out for proteins up to 3837 atoms at the HF/6-31G* level. As compared to standard full system CPCM calculations, EE-GMFCC-CPCM shows clear improvement over the MFCC-CPCM method for both the total electrostatic solvation energy and its components (the polarized solute-solvent reaction field energy and wavefunction distortion energy of the solute). For large proteins with 1000–4000 atoms, where the standard full system ab initio CPCM calculations are not affordable, the EE-GMFCC-CPCM gives larger relative wavefunction distortion energies and weaker relative electrostatic solvation energies for proteins, as compared to the corresponding energies calculated by the Divide-and-Conquer Poisson-Boltzmann (D&C-PB) method. Notwithstanding, a high correlation between EE-GMFCC-CPCM and D&C-PB is observed. This study demonstrates that the linear-scaling EE-GMFCC-CPCM approach is an accurate and also efficient method for the calculation of electrostatic solvation energy of proteins.
Kinetics of germanium nanowire growth by the vapor-solid-solid mechanism with a Ni-based catalyst
Authors: Thombare Shruti V. , Marshall Ann F. , McIntyre Paul C.
Published: December 2013

The kinetics of vapor-solid-solid (VSS) Ge nanowire growth using a Ni-based catalyst were investigated to probe the rate-limiting step for this complex nanoscale crystal growth process. The effects of key parameters such as temperature and precursor partial pressure on the nanowire growth rate were studied in order to gain detailed insights into the growth kinetics. Two different regimes were observed for VSS growth of Ge nanowires as function of temperature. At higher temperatures (345 °C–375 °C), kinetics data suggest that mass transport of germane precursor to the catalyst surface is rate limiting. At lower temperatures (<345 °C), either surface reaction of the GeH4 precursor on the catalyst or incorporation of Ge into the nanowire across the wire/catalyst interface is rate limiting.
Spatio-temporal hierarchy in the dynamics of a minimalist protein model
Authors: Matsunaga Yasuhiro , Baba Akinori , Li Chun-Biu , Straub John E. , Toda Mikito , Komatsuzaki Tamiki , Berry R. Stephen
Published: December 2013

A method for time series analysis of molecular dynamics simulation of a protein is presented. In this approach, wavelet analysis and principal component analysis are combined to decompose the spatio-temporal protein dynamics into contributions from a hierarchy of different time and space scales. Unlike the conventional Fourier-based approaches, the time-localized wavelet basis captures the vibrational energy transfers among the collective motions of proteins. As an illustrative vehicle, we have applied our method to a coarse-grained minimalist protein model. During the folding and unfolding transitions of the protein, vibrational energy transfers between the fast and slow time scales were observed among the large-amplitude collective coordinates while the other small-amplitude motions are regarded as thermal noise. Analysis employing a Gaussian-based measure revealed that the time scales of the energy redistribution in the subspace spanned by such large-amplitude collective coordinates are slow compared to the other small-amplitude coordinates. Future prospects of the method are discussed in detail.
Resummed thermodynamic perturbation theory for bond cooperativity in associating fluids
Authors: Marshall Bennett D. , Chapman Walter G.
Published: December 2013

We develop a resummed thermodynamic perturbation theory for bond cooperativity in associating fluids by extension of Wertheim's multi-density formalism. We specifically consider the case of an associating hard sphere with two association sites and both pairwise and triplet contributions to the energy, such that the first bond in an associated cluster receives an energy −ɛ(1) and each subsequent bond in the cluster receives an energy −ɛ(2). To test the theory we perform new Monte Carlo simulations for potentials of this type. Theory and simulation are found to be in excellent agreement. We show that decreasing the energetic benefit of hydrogen bonding can actually result in a decrease in internal energy in the fluid. We also predict that when ɛ(1) = 0 and ɛ(2) is nonzero there is a transition temperature where the system transitions from a fluid of monomers to a mixture of monomers and very long chains.
Slow dynamics of a protein backbone in molecular dynamics simulation revealed by time-structure based independent component analysis
Authors: Naritomi Yusuke , Fuchigami Sotaro
Published: December 2013

We recently proposed the method of time-structure based independent component analysis (tICA) to examine the slow dynamics involved in conformational fluctuations of a protein as estimated by molecular dynamics (MD) simulation [Y. Naritomi and S. Fuchigami, J. Chem. Phys. 134, 065101 (2011)]. Our previous study focused on domain motions of the protein and examined its dynamics by using rigid-body domain analysis and tICA. However, the protein changes its conformation not only through domain motions but also by various types of motions involving its backbone and side chains. Some of these motions might occur on a slow time scale: we hypothesize that if so, we could effectively detect and characterize them using tICA. In the present study, we investigated slow dynamics of the protein backbone using MD simulation and tICA. The selected target protein was lysine-, arginine-, ornithine-binding protein (LAO), which comprises two domains and undergoes large domain motions. MD simulation of LAO in explicit water was performed for 1 μs, and the obtained trajectory of Cα atoms in the backbone was analyzed by tICA. This analysis successfully provided us with slow modes for LAO that represented either domain motions or local movements of the backbone. Further analysis elucidated the atomic details of the suggested local motions and confirmed that these motions truly occurred on the expected slow time scale.
Rational extension and Jacobi-type X
m solutions of a quantum nonlinear oscillator
Authors: Schulze-Halberg Axel , Roy Barnana
Published: December 2013

We construct a rational extension of a recently studied nonlinear quantum oscillator model. Our extended model is shown to retain exact solvability, admitting a discrete spectrum and corresponding closed-form solutions that are expressed through Jacobi-type Xm exceptional orthogonal polynomials.
Dual-frequency focused ultrasound using optoacoustic and piezoelectric transmitters for single-pulsed free-field cavitation in water
Authors: Baac Hyoung Won , Lee Taehwa , Ok Jong G. , Hall Timothy , Jay Guo L.
Published: December 2013

Pulsed ultrasonic cavitation is a promising modality for non-contact targeted therapy, enabling mechanical ablation of the tissue. We demonstrate a spatio-temporal superposition approach of two ultrasound pulses (high and low frequencies) producing a tight cavitation zone of 100 μm in water, which is an-order-of-magnitudes smaller than those obtained by the existing high-amplitude transducers. Particularly, laser-generated focused ultrasound (LGFU) was employed for the high-frequency operation (15 MHz). As demonstrated, LGFU plays a primary role to define the cavitation zone. The generation rate of cavitation bubbles could be dramatically increased up to 4.1% (cf. 0.06% without the superposition) with moderated threshold requirement.
Energy localization on the Al sublattice of Pt3Al with L12 order
Authors: Medvedev N. N. , Starostenkov M. D. , Manley M. E.
Published: December 2013

A three-dimensional molecular-dynamics model of Pt3Al with L12 order was developed and found to support the excitation of discrete breathers (DBs) and energy localization on the Al sublattice. For an initial lattice temperature of 0 K, large-amplitude DBs polarized along [100] are found to be very weakly damped, retaining most of their initial energy for more than 1000 cycles, while DBs polarized along [111] damped out over ∼15 cycles. Because the DBs and their dissipation channels are confined to the Al sublattice, long-lived nonequilibrium states with large energy differences between the Al and Pt sublattices occur. Since collisions during irradiation more efficiently generate lattice vibrations in light atoms than heavy atoms, such nonequilibrium states may occur and alter the relaxation processes occurring during radiation damage.
Investigation of low field dielectric properties of anisotropic porous Pb(Zr,Ti)O3 ceramics: Experiment and modeling
Authors: Olariu C. S. , Padurariu L. , Stanculescu R. , Baldisserri C. , Galassi C. , Mitoseriu L.
Published: December 2013

Anisotropic porous Pb(Zr,Ti)O3 ceramics with various porosity degrees have been studied in order to determine the role of the pore shape and orientation on the low-field dielectric properties. Ceramic samples with formula Pb(Zr0.52Ti0.48)0.976Nb0.024O3 with different porosity degrees (dense, 10%, 20%, 40% vol.) have been prepared by solid state reaction. Taking into consideration the shape and orientation of the pore inclusions, the dielectric properties of porous ceramics have been described by using adapted mixing rules models. Rigorous bounds, derived on the basis on Variational Principle, were used to frame dielectric properties of porous composites. The finite element method (FEM) was additionally used to simulate the dielectric response of the porous composites under various applied fields. Among the few effective medium approximation models adapted for anisotropic oriented inclusions, the best results were obtained in case of needle-like shape inclusions (which do not correspond to the real shape of microstructure inclusions). The general case of Wiener bounds limited well the dielectric properties of anisotropic porous composites in case of parallel orientation. Among the theoretical approaches, FEM technique allowed to simulate the distribution of potential and electric field inside composites and provided a very good agreement between the computed permittivity values and experimental ones.
Influence of explosive density on mechanical properties of high manganese steel explosion hardened
Authors: Hu Xiaoyan , Shen Zhaowu , Liu Yingbin , Liu Tiansheng , Wang Fengying
Published: December 2013

The explosion hardening tests of high manganese steel were carried out by using two kinds of explosives of the same composition but different density, respectively. The detonation velocities were tested and the relevant mechanical properties were studied. The results show that the stronger single impulse acting on the specimen, the more hardness of surface increases and the more impact toughness decreases. Compared with the explosive of 1.48 g/cm3 density, the hardness, elongation rate, and impact toughness of the sample for triple explosion with explosive of 1.38 g/cm3 density are larger at the same hardening depth. In addition, the tensile strength of the sample for triple explosion with density of 1.38 g/cm3 is higher from the surface to 15 mm below the surface hardened.
An approach to reduce the antiferromagnetic coupling of antiphase boundaries in half-metallic magnetite films
Authors: Li P. , Cui W. Y. , Bai H. L.
Published: December 2013

Highly conductive (∼105 μΩ cm) Mn doped epitaxial Fe3O4 films were fabricated by reactive sputtering. The larger size of magnetic domains compared to grain size with the increasing Mn content indicates that the partial antiferromagnetic coupling across the antiphase boundaries has been weakened, which was further demonstrated by the smaller exchange bias, faster saturated magnetization, and decreasing exchange interaction JAF. The decrease of antiferromagnetic strength originates from the larger Mn-O bond length than that of Fe-O bond. The first-principle calculation shows that the half-metallic feature (100% spin polarization) of Fe3O4 was unchanged with the incorporation of Mn atoms.
Grain size effect on site-disorder and magnetic properties of multiferroic GaFeO3 nanoparticles
Authors: Han T. C. , Chen T. Y. , Lee Y. C.
Published: December 2013

GaFeO3 (GFO) nanoparticles with different grain sizes (16–152 nm) have been synthesized by a modified Pechini method. The magnetic characterization indicates that with decreasing grain size, the ferrimagnetic transition temperature (TC) increases from 275 to 325 K. The magnetic hysteresis curves measured below TC exhibit two-phase-like magnetic behavior consisting of soft and hard magnetic phases. The results could be explained by the site-disorder of the cations in GFO. Furthermore, thermo-magnetic irreversibility and cusp in zero-field cooled magnetization are observed for all the GFO nanoparticles, which are attributed to the inherent magnetic anisotropy.
Towards rapid nanoscale measurement of strain in III-nitride heterostructures
Authors: Jones Eric , Cooper David , Rouviere Jean-Luc , Béché Armand , Azize Mohamed , Palacios Tomás , Gradečak Silvija
Published: December 2013

We report the structural and compositional nanoscale characterization of InAlN/GaN nanoribbon-structured high electron mobility transistors (HEMTs) through the use of geometric phase analysis (GPA) and nanobeam electron diffraction (NBED). The strain distribution in the HEMT layer is quantified and compared to the expected strain profile for the nominal structure predicted by finite element analysis (FEA). Using the experimental strain results, the actual structure is determined and used to modify the FEA model. The improved fit of the model demonstrates that GPA and NBED provide a powerful platform for routine and rapid characterization of strain in III-V semiconducting device systems leading to insights into device evolution during processing and future device optimization.
Current transport of the [001]-tilt low-angle grain boundary in high temperature superconductors
Authors: Yue Donghua , Zhang Xingyi , Zhou Jun , Zhou Youhe
Published: December 2013

Current transport in grain boundary is one of the crucial factors which can affect the macro-supercurrent characteristics of the high temperature superconductors. van der Laan et al. [Phys. Rev. Lett. 103, 027005 (2009)] presented the strain dependence of the critical current density with a power-law fitting function, which has been verified by many experimental measurements. Here, we present a theoretical analysis of current transport in the [001]-tilt low angle grain boundary according to the strain energy of dislocation. An analytical expression is obtained which has the similar form of the fitting function, and in which the physical characteristics of parameters are distinct, and their values are close to the reports in literature.
Investigation of electromigration in In2Se3 nanowire for phase change memory devices
Authors: Kang Daegun , Rim Taiuk , Baek Chang-Ki , Meyyappan M. , Lee Jeong-Soo
Published: December 2013

The decomposition of In2Se3 nanowire phase change memory devices during current-driving operation was investigated. The devices were subjected to thermal/electrical stress with current density and electric field during the reset operation at 0.24–0.38 MA/cm2 and 5.3–6.4 kV/cm, respectively. After multiple operation cycles, a change in morphology and composition of the In2Se3 nanowire was observed and led to the device failure. The transmission electron microscopy and energy dispersive analysis indicate that electromigration causes the catastrophic failure by void formation where In atoms migrate toward the cathode and Se atoms migrate toward the anode depending on their electronegativities.
Two-step direct reduction of iron ore pellets by utilization of biomass: Effects of preheating temperature, pellet size and composition
Authors: Luo Siyi , Zhou Yangmin , Yi Chuijie
Published: December 2013

This paper presents an innovative two-step direct reduction ironmaking technology by utilization of biomass. The process was as follows: green pellets were prepared by blending iron ore powder with biomass, dolomite and bentonite; the green pellets were firstly preheated under oxygen-free atmosphere and then reduced by syngas produced from catalytic gasification of biomass. Heat energy for pellet reduction was provided by biomass combustion. The feasibility of the innovative ironmaking technology was studied, and the effects of preheating temperature, pellet size and composition on the quality of direct reduction iron (DRI) were investigated. The results showed that the improvement of DRI quality can be achieved by increasing preheating temperature, decreasing pellet size and the addition of dolomite. Under optimum operation conditions (900 °C of preheating temperature, 8–10 mm of pellet size), 90.1% total iron and 94.9% metallization rate were achieved for DRI.
The brain is big science
Authors: Feder Toni
Published: December 2013

Animal and digital systems figure in international and interdisciplinary research on the brain.
Putting heads together for concussion research
Authors: Feder Toni
Published: December 2013

Advanced imaging and electrophysiological tools bolster neuropsychological and behavioral studies as scientists work to crack the mysteries of traumatic head injury.
Colloid single-layer centrifugation improves post-thaw donkey (Equus asinus) sperm quality and is related to ejaculate freezability
Authors: Ortiz I. , Dorado J. , Acha D. , Gálvez M. J. , Urbano M. , Hidalgo M.
Published: December 2013

The aim of this study was to determine whether colloid single-layer centrifugation (SLC) improves post-thaw donkey sperm quality and if this potential enhancement is related to ejaculate freezability. Semen from Andalusian donkeys was frozen following a standard protocol. SLC was performed on frozen–thawed semen and post-thaw sperm parameters were compared with uncentrifuged samples. Sperm quality was estimated by integrating in a single value sperm motility (assessed by computer-assisted sperm analysis), morphology and viability (evaluated under brightfield or fluorescence microscopy). Sperm freezability was calculated as the relationship between sperm quality obtained before freezing and after thawing. Ejaculates were classified into low, medium and high freezability groups using the 25th and 75th percentiles as thresholds. All sperm parameters were significantly (P < 0.01) higher in SLC-selected samples in comparison to uncentrifuged frozen–thawed semen and several kinematic parameters were even higher than those obtained in fresh semen. The increment of sperm parameters after SLC selection was correlated with ejaculate freezability, obtaining the highest values after SLC in semen samples with low freezability. We concluded that, based on the sperm-quality parameters evaluated, SLC can be a suitable procedure to improve post-thaw sperm quality of cryopreserved donkey semen, in particular for those ejaculates with low freezability.
Eating up the world’s food web and the human trophic level
Authors: Bonhommeau Sylvain , Dubroca Laurent , Le Pape Olivier , Barde Julien , Kaplan David M. , Chassot Emmanuel , Nieblas Anne-Elise
Published: December 2013

Significance

Here we combine ecological theory, demography, and socio-economics to calculate the human trophic level (HTL) and position humans in the context of the food web. Trophic levels are a measure of diet composition and are a basic metric in ecology, but have never been calculated for humans. In the global food web, we discover that humans are similar to anchovy or pigs and cannot be considered apex predators. In addition, we show that, although countries have diverse diets, there are just five major groups of countries with similar dietary trends. We find significant links between HTL and important World Bank development indicators, giving insights into the relationship between socio-economic, environmental, and health conditions and changing dietary patterns.
Optimal control of gene expression for fast proteome adaptation to environmental change
Authors: Pavlov Michael Y. , Ehrenberg Måns
Published: December 2013

Significance

For rapid growth in different environments, bacterial cells must perpetually adapt their enzyme levels to efficiently metabolize different sets of nutrients in different surroundings. When environmental shifts are frequent and swift, the bacteria must rapidly adjust the levels of all their different proteins—their proteome. We have theoretically identified the best gene-expression strategy for rapid proteome adjustment upon environmental change and found simple, general descriptions for the dynamic change of the proteome composition and the adaptation time following such optimal strategy. Our work predicts important aspects of bacterial physiology and connects it with the population genetics and evolution of bacterial populations. Our theory is relevant to understanding antibiotic resistance and the development of strategies for maximal biomass production.
Revisiting Darwin's conundrum reveals a twist on the relationship between phylogenetic distance and invasibility
Authors: Jones Emily I. , Nuismer Scott L. , Gomulkiewicz Richard
Published: December 2013

Significance

The application of phylogenetics is rapidly growing in many areas of biology. In invasion biology, phylogenetic information is now being used in an attempt to understand and predict species invasions. However, there is only a weak foundation for the prevalent predictions of how the phylogenetic distance between native and nonnative species should be related to the invasion success of the nonnative species. In this paper, a mechanistic model of species interactions and evolution is used to generate a unique set of predictions. These predictions deviate significantly from those assumed previously, suggesting that current explanations of phylogenetic distance–invasion relationships must be reevaluated. More generally, the results highlight the importance of considering the details of community processes when interpreting phylogenetic patterns.
Edentulism, beaks, and biomechanical innovations in the evolution of theropod dinosaurs
Authors: Lautenschlager Stephan , Witmer Lawrence M. , Altangerel Perle , Rayfield Emily J.
Published: December 2013

Significance

Edentulism and beaks (rhamphothecae) are distinguishing features among extant birds and are traditionally regarded as a response to weight-saving demands for the evolution of flight. However, keratin-covered beaks paralleled by edentulism appeared in non-avian theropod dinosaurs and as early as the Early Cretaceous. Here, high-resolution, digital biomechanical models of the skull of the Cretaceous therizinosaur
Erlikosaurus andrewsi
are used to investigate the functional significance of these morphological specialisations and adaptations occurring in non-avian, maniraptoriform dinosaurs. Results of finite-element analyses provide evidence that keratinous beaks play an important role in enhancing cranial stability by mitigation stress and strain during feeding and represent an evolutionary innovation developed early in derived theropod dinosaurs.
GluN3A expression restricts spine maturation via inhibition of GIT1/Rac1 signaling
Authors: Fiuza Maria , González-González Immaculada , Pérez-Otaño Isabel
Published: December 2013

Significance

More than 95% of excitatory synaptic contacts form on spines, highly motile dendritic protrusions that emerge, grow, or disappear in response to specific patterns of synaptic activity. This physical rearrangement is most prominent during critical periods of early postnatal life, when young brains are reshaped by experience to encode certain kinds of information. We reveal a mechanism whereby juvenile NMDA-type glutamate receptors containing GluN3A subunits regulate spine rearrangements by controlling the function of G protein-coupled receptor kinase-interacting protein (GIT1). GIT1 is a postsynaptic scaffold that couples stimuli promoting spine maturation to sustained cytoskeletal rearrangements. Binding to GluN3A limits the synaptic targeting of GIT1 and its ability to recruit actin regulators in an activity-dependent manner, providing a mechanism to limit the maturation of nonused synapses.
Molecular-scale hydrophobic interactions between hard-sphere reference solutes are attractive and endothermic
Authors: Chaudhari Mangesh I. , Holleran Sinead A. , Ashbaugh Henry S. , Pratt Lawrence R.
Published: December 2013

Significance

Hydrophobic interactions and other solvent-mediated noncovalent interactions are decisive for the stability and functionality of biomolecular structures over an extended range of conditions. A molecular theory should explain characteristic temperature dependences and help in modeling biomolecular structures and functions. So far, there has been just one theory of hydrophobic interactions, the Pratt–Chandler (PC) theory. The PC theory has not been definitively tested because of lack of quantitative correspondence between systems convenient for theory, simulation, and experiment. The present work adapts simulation results to atomic-scale hard-core models of the PC theory. Surprisingly, from the perspective of the PC theory, these results show that atomic-scale hydrophobic interactions between hard-sphere solutes are attractive and endothermic, thereby identifying a target for improved theories.
On the materials basis of modern society
Authors: Graedel T. E. , Harper E. M. , Nassar N. T. , Reck Barbara K.
Published: December 2013

Significance

Modern life is enabled by the use of materials in its technologies. Over time, these technologies have used a larger and more diverse array of materials. Elemental life cycle analyses yield an understanding of these materials, and a definite concern that arises is that of possible scarcity of some of the elements as their use increases. We studied substitution potential for 62 different metals in their major uses. For a dozen different metals, the potential substitutes for their major uses are either inadequate or appear not to exist at all. Further, for not 1 of the 62 metals are exemplary substitutes available for all major uses.
Oxytocin enhances brain function in children with autism
Authors: Gordon Ilanit , Vander Wyk Brent C. , Bennett Randi H. , Cordeaux Cara , Lucas Molly V. , Eilbott Jeffrey A. , Zagoory-Sharon Orna , Leckman James F. , Feldman Ruth , Pelphrey Kevin A.
Published: December 2013

Significance

This article presents our discovery that intranasal administration of oxytocin enhances activity in the brain for socially meaningful stimuli and attenuates its response to nonsocially meaningful stimuli in children with autism spectrum disorder (ASD) as measured via functional MRI. We also identified a relationship between changes in salivary oxytocin following administration and enhancements in brain function. These discoveries are particularly important given the urgent need for treatments that target the core social dysfunction in ASD. The functional neural attunement we demonstrated might facilitate social learning, thus potentially bringing about long-term change in neural systems and subsequent behavioral improvements. Our results illustrate the power of a translational neuroscience approach to facilitate the development of pharmacological interventions for neurodevelopmental disorders like ASD.
Akt activation enhances ribosomal RNA synthesis through casein kinase II and TIF-IA
Authors: Nguyen Le Xuan Truong , Mitchell Beverly S.
Published: December 2013

Significance

Ribosomal proteins are synthesized in the nucleolus under the control of a number of repetitive DNA elements and are required for cell proliferation. Cancer cells frequently contain mutations that activate the phosphoinositide 3-kinase/Akt signaling pathway. This study shows that activation of Akt enhances the transcription of ribosomal genes by stabilizing a protein, transcription initiation factor I (TIF-IA), which is essential for the transcription of ribosomal DNA. Activated Akt also increases ribosomal RNA synthesis by phosphorylating casein kinase 2, which in turn phosphorylates and enhances the activity of TIF-IA. These results demonstrate new mechanisms by which the activation of Akt can promote tumor cell proliferation and further support the targeting of activated Akt as a potential therapy for certain cancers.
Crystal structures of the carbamoylated and cyanated forms of HypE for [NiFe] hydrogenase maturation
Authors: Tominaga Taiga , Watanabe Satoshi , Matsumi Rie , Atomi Haruyuki , Imanaka Tadayuki , Miki Kunio
Published: December 2013

Significance

[NiFe] hydrogenases carry a [NiFe](CN)
2
CO center at the active site to catalyze the reversible oxidation of hydrogen in microorganisms. Hydrogenase pleiotropically acting protein (Hyp)E synthesizes the CN ligand for [NiFe] hydrogenases by catalyzing the dehydration of primary amide to nitrile. In the case of HypE, the primary amide is the carbamoylated C-terminal cysteine of HypE, and the nitrile is the cyanated cysteine. However, there has been no structural evidence to explain how HypE dehydrates primary amides into nitrile. We have determined the structures of these two intermediate steps of HypE, namely, carbamoylated and cyanated states. These structures reveal the detailed interactions around the carbamoylated and cyanated cysteine, providing structural basis for the biological conversion of primary amide to nitrile.