bluuebunny/crossref_metadata_2025 huggingface dataset:
Incompatible effects of p53 and HDAC inhibition on p21 expression and cell cycle progression
Authors: Sachweh M C C , Drummond C J , Higgins M , Campbell J , Laín S
Published: March 2013

Nutlin-3 selectively activates p53 by inhibiting the interaction of this tumor suppressor with its negative regulator murine double minute 2 (mdm2), while trichostatin A (TSA) is one of the most potent histone deacetylase (HDAC) inhibitors currently available. As both Nutlin-3 and TSA increase the levels of the cell cycle inhibitor p21(cip1/waf1) in cells, we investigated whether a combination of these compounds would further augment p21 levels. Contrary to expectations, we found that short-term exposure to Nutlin-3 and TSA in combination did not have an additive effect on p21 expression. Instead, we observed that activation of p53 prevented the ability of TSA to increase p21 levels. Furthermore, TSA inhibited Nutlin-3-induced expression of p53-dependent mRNAs including P21. This negative effect of TSA on Nutlin-3 was significantly less pronounced in the case of hdm2, another p53 downstream target. Aside from suggesting a model to explain these incompatible effects of Nutlin-3 and TSA, we discuss the implications of our findings in cancer therapy and cell reprogramming.
Nitrification rates in Arctic soils are associated with functionally distinct populations of ammonia-oxidizing archaea
Authors: Alves Ricardo J Eloy , Wanek Wolfgang , Zappe Anna , Richter Andreas , Svenning Mette M , Schleper Christa , Urich Tim
Published: March 2013

The functioning of Arctic soil ecosystems is crucially important for global climate, and basic knowledge regarding their biogeochemical processes is lacking. Nitrogen (N) is the major limiting nutrient in these environments, and its availability is strongly dependent on nitrification. However, microbial communities driving this process remain largely uncharacterized in Arctic soils, namely those catalyzing the rate-limiting step of ammonia (NH3) oxidation. Eleven Arctic soils were analyzed through a polyphasic approach, integrating determination of gross nitrification rates, qualitative and quantitative marker gene analyses of ammonia-oxidizing archaea (AOA) and bacteria (AOB) and enrichment of AOA in laboratory cultures. AOA were the only NH3 oxidizers detected in five out of 11 soils and outnumbered AOB in four of the remaining six soils. The AOA identified showed great phylogenetic diversity and a multifactorial association with the soil properties, reflecting an overall distribution associated with tundra type and with several physico-chemical parameters combined. Remarkably, the different gross nitrification rates between soils were associated with five distinct AOA clades, representing the great majority of known AOA diversity in soils, which suggests differences in their nitrifying potential. This was supported by selective enrichment of two of these clades in cultures with different NH3 oxidation rates. In addition, the enrichments provided the first direct evidence for NH3 oxidation by an AOA from an uncharacterized Thaumarchaeota–AOA lineage. Our results indicate that AOA are functionally heterogeneous and that the selection of distinct AOA populations by the environment can be a determinant for nitrification activity and N availability in soils.
The COUP-TFII variant lacking a DNA-binding domain inhibits the activation of the Cyp7a1 promoter through physical interaction with COUP-TFII
Authors: Yamazaki Tomoko , Suehiro Jun-ichi , Miyazaki Hideki , Minami Takashi , Kodama Tatsuhiki , Miyazono Kohei , Watabe Tetsuro
Published: March 2013

The COUP-TFII (chicken ovalbumin upstream promoter-transcription factor II) nuclear receptor, which is composed of a DNA-binding domain and a ligand-binding domain, exerts pleiotropic effects on development and cell differentiation by regulating the transcription of its target genes, including Cyp7a1 (cytochrome P450, family 7, subfamily a, polypeptide 1), which plays important roles in catabolism of cholesterol in the liver. Although multiple variants of COUP-TFII exist, their roles in the regulation of Cyp7a1 expression have not been elucidated. In the present study, we investigated the roles of COUP-TFII-V2 (variant 2), which lacks a DNA-binding domain, in the regulation of the transcriptional control of the Cyp7a1 gene by COUP-TFII in hepatocellular carcinoma cells. We found that COUP-TFII-V2 was significantly expressed in Huh7 cells, in which Cyp7a1 was not expressed. Furthermore, knockdown of COUP-TFII-V2 enhanced endogenous Cyp7a1 expression in Huh7 cells. Although COUP-TFII activates the Cyp7a1 promoter through direct binding to DNA, this activation was affected by COUP-TFII-V2, which physically interacted with COUP-TFII and inhibited its DNA-binding ability. Chromatin immunoprecipitation assays showed that COUP-TFII-V2 inhibited the binding of endogenous COUP-TFII to the intact Cyp7a1 promoter. The results of the present study suggest that COUP-TFII-V2 negatively regulates the function of COUP-TFII by inhibiting its binding to DNA to decrease Cyp7a1 expression.
Resistance exercise improves autonomic regulation at rest and haemodynamic response to exercise in non-alcoholic fatty liver disease
Authors: Jakovljevic Djordje G. , Hallsworth Kate , Zalewski Pawel , Thoma Christian , Klawe Jacek J. , Day Christopher P. , Newton Julia , Trenell Michael I.
Published: March 2013

Autonomic dysfunction has been reported in patients with NAFLD (non-alcoholic fatty liver disease) and is associated with clinical presentations. To date, there are no therapies to improve autonomic regulation in people with NAFLD. The present study defines the impact of a short-term exercise programme on cardiac autonomic and haemodynamic regulation in patients with NAFLD. A total of 17 patients with clinically defined NAFLD [age, 55±12 years; BMI (body mass index), 33±5 kg/m2; liver fat, 17±9%] were randomized to 8 weeks of resistance exercise or a control group to continue standard care. Resting and submaximal exercise (50% of peak oxygen consumption) autonomic and cardiac haemodynamic measures were assessed before and after the intervention. Resistance exercise resulted in a 14% reduction in HR (heart rate) and 7% lower SBP (systolic blood pressure) during submaximal exercise (16 beats/min, P=0.03 and 16 mmHg, P=0.22). Sympathovagal balance, expressed as LF/HF (low-frequency/high-frequency) ratio of the mean HR beat-to-beat (R–R) interval, was reduced by 37% (P=0.26). Similarly sympathovagal balance of DBP (diastolic blood pressure) and SBP variability decreased by 29% (P=0.33) and 19% (P=0.55), respectively in the exercise group only. BRS (baroreflex sensitivity) increased by 31% (P=0.08) following exercise. The mean R–R interval increased by 23% (159 ms, P=0.09). Parasympathetic regulation was decreased by 17% (P=0.05) and overall sympathovagal balance in BP regulation (LF/HF ratio) increased by 26% (P=0.02) following resistance exercise. Resting haemodynamic measures remained similar between groups. Resistance exercise therapy seems to improve autonomic and submaximal exercise haemodynamic regulation in NAFLD. Further studies are required to define its role in clinical management of the condition.
An Overview of Respiratory Treatments for Individuals With Amyotrophic Lateral Sclerosis
1
Authors: Cleary Stuart , Richman-Eisenstat Janice
Published: March 2013

Given the limited life expectancy of individuals diagnosed with amyotrophic lateral sclerosis (ALS) and the high likelihood that patients will suffer from a breathing difficulty and an encumbered airway, promoting the highest level in the ability to maintain an open and clear airway is of the utmost importance to patients and their families. In this article, authors describe the basic mechanisms of neuromuscular-induced respiratory failure and explain the underlying physiological rationale for four commonly used respiratory treatments in cases of advanced ALS. The article also includes research on the use of manual breath stacking to improve coughing and airway clearance while swallowing.
Efficient softest mode finding in transition states calculations
Authors: Leng Jing , Gao Weiguo , Shang Cheng , Liu Zhi-Pan
Published: March 2013

Transition states are fundamental to understanding the reaction dynamics qualitatively in chemical physics. To date various methods of first principle location of the transition states have been developed. In the absence of the knowledge of the final structure, the softest-mode following method climbs up to a transition state without calculating the Hessian matrix. One weakness of this kind of approaches is that the number of rotations to determine the softest mode is usually unpredictable. In this paper, we propose a locally optimal search direction finding algorithm, namely LOR, which is an extension of the traditional conjugate gradient method without additional calculations of the forces. We also show that the translation of forces improves the numerical stability. Experiments for the Baker test system show that the proposed algorithm is much faster than the original dimer conjugate gradient method.
Topology and dynamics of the A-pillar vortex
Authors: Levy Benjamin , Brancher Pierre
Published: March 2013

The topology and dynamics of the flow bypassing an automobile A-pillar modeled by a 30° dihedron are investigated experimentally. The various components of the A-pillar flow are identified by means of low and high frequency particle image velocimetry. For each component, the time evolution of the position, displacement, vorticity magnitude, circulation, and fluctuating kinetic energy are analyzed along the A-pillar. More precisely, the flow bypassing the A-pillar is composed of two vortex structures with different behaviors. The major structure grows in size, circulation magnitude, and total amount of fluctuating kinetic energy along the A-pillar, whereas the minor structure does not vary significantly. Finally, the displacement of the major structure is identified as a movement of precession and the influence of the A-pillar geometry is emphasized.
Hugoniot and sound velocity measurements of bismuth in the range of 11–70 GPa
Authors: Tan Ye , Yu Yuying , Dai Chengda , Jin Ke , Wang Qingsong , Hu Jianbo , Tan Hua
Published: March 2013

Plate impact experiments in backward-impact geometry were performed on bismuth (Bi) in the pressure range of 11–70 GPa. The bismuth sample used as flyer impacted a LiF window, and the impact velocity and particle velocity at interface were simultaneously measured by a distance interferometer system for any reflector. Hugoniot and sound velocity data were extracted from the observed particle velocity profiles. The obtained plot of shock velocity (D) versus particle velocity (u) showed a discontinuity at u ≈ 0.9 km/s, corresponding to a pressure of ∼27 GPa. Furthermore, plate impact experiments in forward-impact geometry were conducted to measure sound velocities of bismuth. The extracted sound velocity data from backward and forward-impact experiments showed a transition from longitudinal to bulk sound velocity (18 GPa–27 GPa), and the pressure of transition to bulk sound velocity is consistent with the pressure of D-u knee at u ≈ 0.9 km/s. This D-u discontinuity at u ≈ 0.9 km/s is attributed to shock induced melting, and the onset and completion of melting on bismuth Hugoniot are estimated around 18 GPa and 27 GPa, respectively.
Normal and inverse magnetocaloric effects in ferromagnetic Pr0.58Sr0.42MnO3
Authors: Maheswar Repaka D. V. , Aparnadevi M. , Kumar Pawan , Tripathi T. S. , Mahendiran R.
Published: March 2013

We report magnetization, magnetic entropy change (ΔSm), and its correlation with magnetoresistance (MR) in Pr0.58Sr0.42MnO3. It is shown that the magnetization upon field-cooling shows a steplike decrease at TS = 134 K much below the ferromagnetic transition (TC = 300 K). While the low temperature transition is first-order, the high temperature transition is second-order as suggested by the hysteresis behavior in magnetization. In a magnetic field range accessible with an electromagnet, the magnetic entropy decreases at TC (ΔSm = −2.33 J/kg K with a refrigeration capacity of 65.88 J/kg for a magnetic field change of ΔH = 2 T) whereas it increases at TS (ΔSm = +0.7 J/kg K) upon magnetization. The unusual inverse magnetocaloric effect found at TS within ferromagnetic state is ascribed to orthorhombic to monoclinic structural transition. We show that ΔSm versus T curves under different magnetic fields can be collapsed into a single master curve using a scaling method. Importantly, we find that negative MR increases linearly with −ΔSm in the paramagnetic state at all magnetic fields above TC and at higher magnetic fields below TC. Such a close correlation between the magnetoresistance and the magnetic entropy change can be exploited to design efficient magnetocaloric materials.
Elementary steps of the catalytic NOx reduction with NH3: Cluster studies on reactant adsorption at vanadium oxide substrate
Authors: Gruber M. , Hermann K.
Published: March 2013

Extended cluster models together with density-functional theory are used to evaluate geometric, energetic, and electronic properties of different adsorbate species that can occur at a vanadium oxide surface where the selective catalytic reduction (SCR) of NO in the presence of ammonia proceeds. Here, we focus on atomic hydrogen, nitrogen, and oxygen, as well as molecular NO and NHx, x = 1, 4, adsorption at a model V2O5(010) surface. Binding sites, oxygen and vanadium, at both the perfect and reduced surface are considered where reduction is modeled by (sub-) surface oxygen vacancies. The reactants are found to bind overall more strongly at oxygen vacancy sites of the reduced surface where they stabilize in positions formerly occupied by the oxygen (substitutional adsorption) compared with weaker binding at the perfect surface. In particular, ammonia, which interacts only weakly with vanadium at the perfect surface, binds quite strongly near surface oxygen vacancies. In contrast, surface binding of the NH4 adsorbate species differs only little between the perfect and the reduced surface which is explained by the dominantly electrostatic nature of the adsorbate interaction. The theoretical results are consistent with experimental findings and confirm the importance of surface reduction for the reactant adsorption forming elementary steps of the SCR process.
An optically transparent thin-layer electrochemical cell for the study of vibrational circular dichroism of chiral redox-active molecules
Authors: Domingos Sérgio R. , Luyten Henk , van Anrooij Fred , Sanders Hans J. , Bakker Bert H. , Buma Wybren J. , Hartl František , Woutersen Sander
Published: March 2013

An optically transparent thin-layer electrochemical (OTTLE) cell with a locally extended optical path has been developed in order to perform vibrational circular dichroism (VCD) spectroscopy on chiral molecules prepared in specific oxidation states by means of electrochemical reduction or oxidation. The new design of the electrochemical cell successfully addresses the technical challenges involved in achieving sufficient infrared absorption. The VCD-OTTLE cell proves to be a valuable tool for the investigation of chiral redox-active molecules.
Modeling the temperature dependent interfacial tension between organic solvents and water using dissipative particle dynamics
Authors: Mayoral E. , Goicochea A. Gama
Published: March 2013

The interfacial tension between organic solvents and water at different temperatures is predicted using coarse-grained, mesoscopic Dissipative Particle Dynamics (DPD) simulations. The temperature effect of the DPD repulsive interaction parameters, aij, for the different components is calculated from the dependence of the Flory-Huggins χ parameter on temperature, by means of the solubility parameters. Atomistic simulations were carried out for the calculation of the solubility parameters for different organic compounds at different temperatures in order to estimate χ and then the aij coefficients. We validate this parametrization through the study of the interfacial tension in a mixture of benzene and water, and cyclohexane and water, varying the temperature. The predictions of our simulations are found to be in good agreement with experimental data taken from the literature, and show that the use of the solubility parameter at different temperatures to obtain the repulsive DPD parameters is a good alternative to introduce the effect of temperature in these systems.
Electric linear dichroism transients of bent DNA fragments
Authors: Umazano Juan P. , Bertolotto Jorge A.
Published: March 2013

We study the effect of translational-rotational hydrodynamic coupling on the transient electric linear dichroism of DNA fragments in aqueous solution. As opposed to previous theoretical works, where analytic solutions valid in the limit of low electric field were reported, we present here a numerical approach which allows to obtain numerical results valid independently from the applied electric field strength. Numerical procedures here used are an extension to the transient-state of those developed in a previous work for the study of the problem in the steady-state. The molecular orientational processes induced by an electric field is characterized with statistical arguments solving the Fokker-Planck equation by means of the finite difference method to know the orientational distribution function of molecules.
Quantitative determination of mass-resolved ion densities in H2-Ar inductively coupled radio frequency plasmas
Authors: Sode M. , Schwarz-Selinger T. , Jacob W.
Published: March 2013

Inductively coupled H2-Ar plasmas are characterized by an energy-dispersive mass spectrometer (plasma monitor), a retarding field analyzer, optical emission spectroscopy, and a Langmuir probe. A procedure is presented that allows determining quantitatively the absolute ion densities of Ar+, H+, H2+, H3+, and ArH+ from the plasma monitor raw signals. The calibration procedure considers the energy and mass-dependent transmission of the plasma monitor. It is shown that an additional diagnostic like a Langmuir probe or a retarding field analyzer is necessary to derive absolute fluxes with the plasma monitor. The conversion from fluxes into densities is based on a sheath and density profile model. Measurements were conducted for a total gas pressure of 1.0 Pa. For pure H2 plasmas, the dominant ion is H3+. For mixed H2-Ar plasmas, the ArH+ molecular ion is the most dominant ion species in a wide parameter range. The electron density, ne, is around 3×1016 m−3 and the electron temperature, Te, decreases from 5 to 3 eV with increasing Ar content. The dissociation degree was measured by actinometry. It is around 1.7% nearly independent on Ar content. The gas temperature, estimated by the rotational distribution of the Q-branch lines of the H2 Fulcher-α diagonal band (v′=v″=2) is estimated to (540 ± 50) K.
Lateral Interaction of transverse magnetic domain walls
Authors: Nam Chunghee , Mascaro M. D. , Ross C. A.
Published: March 2013

Magnetic domain walls (DWs) that are spatially close are formed with 360° (360DW) or 540° (540DW) configurations in Co magnetic rings. The 360DW is formed in a continuous magnetic structure whereas the 540DW configuration comprises the 360DW and 180DW with a narrow nonmagnetic gap. Individual transverse DWs play a key role in forming 360DWs or 540DWs because their magnetic polarity and chirality reduce the magnetostatic energy depending on the DW configurations. The magnetostatic interaction between individual DWs results in the variation of the local stray field, which is consistent with micromagnetic simulations.
Static and dynamic properties of Fibonacci multilayers
Authors: Machado L. D. , Bezerra C. G. , Correa M. A. , Chesman C. , Pearson J. E. , Hoffmann A.
Published: March 2013

We theoretically investigate static and dynamic properties of quasiperiodic magnetic multilayers. We considered identical ferromagnetic layers separated by non-magnetic spacers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr, the minimum energy was determined and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. Regarding dynamic behavior, ferromagnetic resonance (FMR) curves were calculated using an approximation known from the literature. Our numerical results illustrate the effects of quasiperiodicity on the static and dynamic properties of these structures.
Mechanisms for room temperature direct wafer bonding
Authors: Plach T. , Hingerl K. , Tollabimazraehno S. , Hesser G. , Dragoi V. , Wimplinger M.
Published: March 2013

Reducing the temperature needed for high strength bonding which was and is driven by the need to reduce effects of coefficient of thermal expansion mismatch, reduce thermal budgets, and increase throughput has led to the development of plasma treatment procedures capable of bonding Si wafers below 300 °C with a bond strength equivalent to Si bulk. Despite being widely used, the physical and chemical mechanisms enabling low temperature wafer bonding have remained poorly understood. We developed an understanding of the beneficial surface modifications by plasma and a model based on short range low temperature diffusion through bonding experiments combined with results from spectroscopic ellipsometry, depth resolving Auger electron spectroscopy, and transmission electron microscopy measurements. We also present experimental results showing that even at room temperature reasonable bond strength can be achieved. We conclude that the gap closing mechanism is therefore a process which balances the lowering of the total energy by minimizing the sum of the free surface energy (maximizing the contact area between the surfaces) and strain energy in the oxide at the bond interface.
Closely spaced nanomagnets by dual e-beam exposure for low-energy nanomagnet logic
Authors: Shah Faisal A. , Csaba Gyorgy , Butler Katherine , Bernstein Gary H.
Published: March 2013

The effect of nanomagnet spacing on required clock field has been studied by micromagnetic simulation for supermalloy (Ni79Fe16Mo5) dots with dimensions 90 × 60 × 20 nm3 and 120 × 60 × 20 nm3. Reduction of the inter-magnet spacing for both dimensions has resulted in reduction of the required clock field in the simulation. A dual e-beam exposure technique has been developed to allow fabrication of ultra dense features using conventional poly(methylmethacrylate) e-beam resist. Nanomagnet logic (NML) datalines of supermalloy dots with ∼10 nm and ∼15 nm spacing have been fabricated using dual e-beam exposure with a 3σ overlay accuracy of ∼4 nm. Fabricated NML datalines have been characterized using magnetic force microscopy for various clock fields. Datalines of both spacing have shown proper NML functionality with a clock field as low as 60 mT.
On the kinetics of MoSe2 interfacial layer formation in chalcogen-based thin film solar cells with a molybdenum back contact
Authors: Shin Byungha , Bojarczuk Nestor A. , Guha Supratik
Published: March 2013

We have studied the temperature dependent kinetics of MoSe2 formation between molybdenum and Cu2ZnSnSe4 (CZTSe) films during annealing in the presence of Se. CZTSe is an emerging light-absorbing material for thin film solar cell applications, and thermal treatment of this layer constitutes a critical part of the device processing. The formation of MoSe2 in this system is modeled using a three step mechanism—diffusion of Se through CZTSe, diffusion of Se through MoSe2, and reaction between Se and Mo. Applying the results of the model to experimental results reveals that the MoSe2 formation is limited by the diffusion of Se through the CZTSe layer.
Fatty acid methyl ester production from waste cooking oil catalyzed by CuO-CeO2/NiO mixed oxides
Authors: Tajammul Hussain Syed , Ahmed Waqas , Saeed Maria , Danish Ali Syed , Asma Maliha
Published: March 2013

The diminution of edible oils and increasing cost of edible oils and biodiesel have gained the interest of many researchers for non-edible oils as biodiesel feed stock. The major hurdle in the commercialization of biodiesel is the high cost of feedstock. Due to fast mushrooming of fast food centers, waste cooking oil is one of the most economical feedstock available for the biodiesel production. The high free fatty acid contents and moisture in the waste cooking oil hinders the homogenous transesterification for the commercial purposes. Mixed oxides of Cu with Ni and Ce were synthesized by co-precipitation method and their efficacy for the production of biodiesel from the waste cooking oil was inspected. The acid catalyzed heterogeneous transesterification of waste cooking oil was performed in the sealed container. It was also interesting to mention that no pre-treatment was executed for the waste cooking oil conversion to biodiesel. It was investigated that mixed oxide catalyst CuO-CeO2 proved to be the potential candidate in pilot scale biodiesel production from waste cooking oil having about 92% conversion rate. Comprehensive chemical analysis of biodiesel including NMR, GC-MS, and FT-IR supports our result.
Direct observation of electro-optic modulation in a single split-ring resonator
Authors: Shchegolkov Dmitry Yu. , Reiten Matthew T. , O'Hara John F. , Azad Abul K.
Published: March 2013

We study experimentally and numerically the electro-optic (EO) effect in a single metamaterial cell incorporating a nonlinear crystal. A metal split-ring fabricated on a ZnTe substrate resonating at 3 GHz was excited with a tunable microwave source. A linearly polarized laser beam probed the EO effect. Enhanced EO modulation was observed in the split-gap at the resonant frequency proportional to Q-factor. The electric field surrounding the metamaterial element in the ZnTe was mapped by the EO effect and agrees well with simulation. We show that high-Q metamaterials incorporating an EO crystal in the split-gap could lead to improved EO devices.
Strong magnetoelectric coupling in hexaferrites at room temperature
Authors: Ebnabbasi Khabat , Mohebbi Marjan , Vittoria Carmine
Published: March 2013

In this paper, the magnetoelectric effect in single-crystalline Sr Z-type hexaferrite materials is reported. The measurements include material characterization and change in remanence magnetization (Mr) versus electric field. In a very low electric field equal to 3.75 V/cm, 14% change in Mr was observed. We deduced a magneto-electric coupling of 55.4 in CGS units or 2.32 × 10−6 sm−1 (SI units) which is the highest value measured to date.
Mechanism of Li intercalation into Si
Authors: Kaghazchi Payam
Published: March 2013

Using density functional theory calculations, we study intercalation of Li into Si via Si(100) and (111) surfaces. We find that in contact with Li atoms, the surfaces are covered with a high coverage of Li adatoms. Insertion of Li into Si only takes place from (100) surface via a pushing mechanism. In this mechanism, Li atoms that have already adsorbed on the (100) surface are repelled by nearly adsorbed Li atoms and pushed down to penetrate into the subsurface. This mechanism is not possible on Si(111) on which the adsorbed Li atoms block the penetration of Li atoms. Since Si is a promising candidate to replace the graphite in Li-ion batteries, the present work can help us to better understand the process of Li insertion and extraction in Si anode materials of future batteries.
Energy band alignment of atomic layer deposited HfO2 on epitaxial (110)Ge grown by molecular beam epitaxy
Authors: Hudait M. K. , Zhu Y. , Maurya D. , Priya S.
Published: March 2013

The band alignment properties of atomic layer HfO2 film deposited on epitaxial (110)Ge, grown by molecular beam epitaxy, was investigated using x-ray photoelectron spectroscopy. The cross-sectional transmission electron microscopy exhibited a sharp interface between the (110)Ge epilayer and the HfO2 film. The measured valence band offset value of HfO2 relative to (110)Ge was 2.28 ± 0.05 eV. The extracted conduction band offset value was 2.66 ± 0.1 eV using the bandgaps of HfO2 of 5.61 eV and Ge bandgap of 0.67 eV. These band offset parameters and the interface chemical properties of HfO2/(110)Ge system are of tremendous importance for the design of future high hole mobility and low-power Ge-based metal-oxide transistor devices.
Magnetotransport dependence on the field magnitude and direction in large area epitaxial graphene film on stretchable substrates
Authors: Bao Peite , Li Wenxian , Kong Yeoh Wai , Cui Xiangyuan , Ho Kim Jung , Kang Yong-Mook , Yang Wenrong , Xue Dou Shi , Ringer Simon P. , Zheng Rongkun
Published: March 2013

We report the magnetotransport properties of large area graphene on stretchable polyethylene terephthalate substrates. At 2 K, weak localization of electrons introduced negative magnetoresistance at low field; a transition to positive magnetoresistance followed as the external field increases. Our results suggest that weak localization contributes to Hall effect at low temperature. At room temperature, only classical Lorentz force contribution can be observed. Angular dependence of the external magnetic field on longitudinal and transverse resistivity is measured to test the interplay between weak localization and Lorentz force contribution. Quantitative simulations based on quantum interference theory produced excellent agreement with the experiments.
Quantum coherence-assisted propagation of surface plasmon polaritons
Authors: Jha Pankaj K. , Yin Xiaobo , Zhang Xiang
Published: March 2013

We theoretically demonstrate coherent control over propagation of surface plasmon polaritons (SPP), at both telecommunication and visible wavelengths, on a metallic surface adjacent to quantum coherence (phaseonium) medium composed of three-level quantum emitters (semiconductor quantum dots, atoms, rare-earth ions, etc.) embedded in a dielectric host. The coherent drive allows us to provide sufficient gain for lossless SPP propagation and also lowers the pumping requirements. In case of lossy propagation, an order of magnitude enhancement in propagation length can be achieved. Optical control over SPP propagation dynamics via an external coherent drive holds promise for quantum control in the field of nanophotonics.
Note: Near-field imaging of thermal radiation at low temperatures by passive millimeter-wave microscopy
Authors: Nozokido T. , Ishino M. , Kudo H. , Bae J.
Published: March 2013

Imaging of thermal radiation with a spatial resolution below the diffraction limit is demonstrated with a passive millimeter-wave microscope. This technique utilizes a sensitive radiometric receiver in combination with a scanning near-field microscope. Experiments were performed at 50 GHz (λ = 6 mm) with sample temperatures ranging from room temperature down to 160 K, and the performance was shown to be superior to that achieved with passive imaging systems in the infrared region. The images are affected by non-uniformities in the transmission of thermal radiation from the sample to the receiver via the near-field probe and the reflection of thermal radiation back to the receiver from the probe. The effects of these non-uniformities were successfully removed using a sample image acquired by active measurements using a vector network analyzer.
Band alignment of ZnTe/GaAs heterointerface investigated by synchrotron radiation photoemission spectroscopy
Authors: Guo Qixin , Takahashi Kazutoshi , Saito Katsuhiko , Akiyama Hajime , Tanaka Tooru , Nishio Mitsuhiro
Published: March 2013

ZnTe films have been grown on GaAs substrate by metalorganic vapor phase epitaxy. High-resolution synchrotron radiation photoemission spectroscopy measurements are used to determine the valence band offset of ZnTe/GaAs heterojunctions. Based on the binding energies of Zn 3d and Ga 3d core levels and valence band maximum values, the valence band offset has been determined to be 0.19 eV for ZnTe/GaAs heterojunction. The heterojunction shows type I band configuration with a conduction band offset of 0.65 eV. The accurate determination of the band alignment of ZnTe/GaAs heterojunction facilitates the design of optical and electronic devices based on ZnTe/GaAs structure.
A theoretical analysis of the role of defects in the adsorption of hydrogen sulfide on graphene
Authors: Castellanos Águila J. E. , Cocoletzi H. Hernández , Cocoletzi G. Hernández
Published: March 2013

Density functional theory studies are reported to analyze the interaction between hydrogen sulfide (H2S) and graphene. The electron-ion interactions have been modeled using ultrasoft pseudopotentials and the exchange-correlation energies have been approximated by the method of the generalized gradient approximation in the parameterization of Perdew-Burke-Ernzerhof. Three graphene structures, one intrinsic and two with defects (vacancy and sustitution), and four H2S concentrations have been studied. The optimal geometries, binding energies, density of states (DOS) and charge density were obtained. In order to study the adsorption process three high symmetry sites were considered, namely, top, bridge, and center. The preferential adsorption structure corresponds to the center site in a physical way. The DOS of graphene-H2S systems shows a metallic behavior which coincides with the behavior of the isolated graphene. The geometrical structure of the graphene and the hydrogen sulfide remains unchanged.
Amphicarpy in Trifolium argentinense: morphological characterisation, seed production, reproductive behaviour and life strategy
Authors: Conterato Ionara Fatima , Schifino-Wittmann Maria Teresa , Guerra Divanilde , Dall'Agnol Miguel
Published: March 2013

Trifolium argentinense Speg. is an amphicarpic species that occurs naturally in native pastures of Rio Grande do Sul, southern Brazil. Amphicarpy is a rare mode of reproduction in which aerial and subterranean seeds are produced by the same individual. In the present paper, we compare morphology, anther number, pollen viability, seed production and mode of reproduction of T. argentinense flowers, and comment on the life strategy of the species. Plants grown from aerial seeds and from the regrowth of storage roots of aerial plants had longer stolons and a larger plant diameter than did those grown from subterranean plants. Plants grown from seeds were also taller than plants grown from storage roots. More resources were allocated to subterranean reproduction in plants of subterranean origin than in those of aerial origin. Aerial flowers produced more seeds, presented more anthers and produced more pollen grains than did the subterranean ones. T. argentinense is a versatile species, self- and cross-pollinated, consistent with the values of high polymorphism information content. T. argentinense adopts the ‘pessimistic strategy’ (early allocation of energy to large subterranean propagules), common in amphicarpic species when growing in disturbed habitats, such as the native pastures of Rio Grande do Sul, where intense grazing and trampling, as well as long seasonal dry spells, may periodically destroy the aerial plants, thus assuring survival by germination of subterranean seeds and regrowth of storage roots.
Aggregation of Hydrogen Bonded Dimeric Tri-Organotin Amino Substituted Pyrimidine-2-Thiolates
Authors: Ioannidou Anastasia , Czapik Agnieszka , Gkizis Petros , Perviaz Muhamad , Tzimopoulos Dimitrios , Gdaniec Maria , Akrivos Pericles D.
Published: March 2013

The synthesis of six tri-organotin compounds with 4-amino and 4,6-diaminopyrimidine-2-thiolate is described. The compounds have the general formula R3Sn(thiolate) where R = Me, Bu, or Ph. The compounds are investigated by a variety of spectroscopic techniques both in solution and in the solid state. The environment around the tin centres proves to be tetrahedral with monodentate thiolate anions as is inferred from the infrared and NMR spectra. The coordination sphere is not affected even by the presence of DMSO as solvent. In the solid state, the crystal structure determination of the trimethyl and triphenyltin derivatives of the 4,6-diaminopyrimidine-2-thiolate ligand, reveal an association into centrosymmetric dimers through N–H⋯N hydrogen-bonding interactions leaving the organotin site practically unaffected. However, in addition to the classical hydrogen bonding, weaker N–H⋯RS and N–H⋯Rπ interactions are also present and play an important role in determining further aggregation of these dimers which gives rise to a three-dimensional polymeric structure in the case of the trimethyltin and a layer of dimers in the case of the triphenyltin derivative, respectively.
Sources of ultrafine particles and chemical species along a traffic corridor: comparison of the results from two receptor models
Authors: Friend Adrian J. , Ayoko Godwin A. , Jager Daniel , Wust Megan , Jayaratne E. Rohan , Jamriska Milan , Morawska Lidia
Published: March 2013

Environmental context Identifying the sources responsible for air pollution is crucial for reducing the effect of the pollutants on human health. The sources of the pollutants were found here by applying two mathematical models to data consisting of particle size distribution and chemical composition data. The identified sources could be used as the basis for controlling or reducing emissions of air pollution into the atmosphere. Abstract Particulate matter is common in our environment and has been linked to human health problems particularly in the ultrafine size range. In this investigation, the sources of particles measured at two sites in Brisbane, Australia, were identified by analysing particle number size distribution data, chemical species concentrations and meteorological data with two source apportionment models. The source apportionment results obtained by positive matrix factorisation (PMF) and principal component analysis–absolute principal component scores (PCA–APCS) were compared with information from the gaseous chemical composition analysis. Although PCA–APCS resolved more sources, the results of the PMF analysis appear to be more reliable. Six common sources were identified by both methods and these include: traffic 1, traffic 2, local traffic, biomass burning and two unassigned factors. Thus motor vehicle related activities had the greatest effect on the data with the average contribution from nearly all sources to the measured concentrations being higher during peak traffic hours and weekdays. Further analyses incorporated the meteorological measurements into the PMF results to determine the direction of the sources relative to the measurement sites, and this indicated that traffic on the nearby road and intersection was responsible for most of the factors. The described methodology that utilised a combination of three types of data related to particulate matter to determine the sources and combination of two receptor models could assist future development of particle emission control and reduction strategies.
Differential response of root proteome to drought stress in drought sensitive and tolerant sunflower inbred lines
Authors: Ghaffari Mehdi , Toorchi Mahmoud , Valizadeh Mostafa , Komatsu Setsuko
Published: March 2013

Productivity of sunflower (Helianthus annuus L.), the fourth most important oilseed crop, is strongly dependent on water availability. To search for genetic variation in the ability of roots to grow into drying soil, 16 sunflower lines were screened in 2 years field experiments by imposing drought stress at flowering stage. The results differentiated RGK 21 and BGK 329 as the most sensitive and tolerant lines respectively. The time course physiological assay of these lines at seedling stage revealed roots as the most affected organ 6 days after imposing drought stress. A proteomics approach was adapted for investigating of differential changes in roots proteome under contrasting moisture regimes. Protein spots with significant changes in protein abundance were identified by nano LC-MS/MS. The results indicated that under drought stress relative abundance of metabolism related proteins were decreased in both sensitive and tolerant lines. Abundance of energy and disease/defence related proteins were decreased in the sensitive but increased in the tolerant line. The results indicate that changes in energy usage, water transport and ROS scavenging are important mechanisms for maintaining root growth as the soil dries.
Within the boundary fence: an investigation into the perceptions of men’s experience of depression in rural and remote areas of Australia
Authors: Patterson-Kane Lisa , Quirk Frances
Published: March 2013

This is a study exploring perceptions of men’s experience of depression in rural and remote areas of Australia. The purpose of this investigation was to generate ‘new’ information that can inform models of diagnosis and primary care for the treatment of depression in men in rural and remote areas. Men and women were recruited from two North Queensland sites to participate in semistructured interviews in both an individual and focus group format and completing a series of questionnaires. A combination of grounded theory and content analysis was adopted to analyse the qualitative data, and develop theory around men’s experience of depression in rural and remote areas. The findings of this study suggest that men’s experience of depression within a rural context is defined by a process of ‘internal compound’ whereupon emotional distress can represent itself in avoidant and dulling behaviours along with self-reliant attempts to ‘fix’ the situation. From this study a language has been provided to give explanation to the experience of depression in men in rural and remote areas. The findings of this study have implications for, and provide opportunity for reform in, how we approach the recognition, diagnosis and treatment of depression for men in rural and remote areas.
Paternally inherited genetic markers reveal new insights into genetic structuring within Macropus fuliginosus and hybridisation with sympatric Macropus giganteus
Authors: Neaves Linda E. , Zenger Kyall R. , Prince Robert I. T. , Eldridge Mark D. B.
Published: March 2013

There are several aspects of biology in which the contribution of males and females is unequal. In these instances the examination of Y chromosome markers may be used to elucidate male-specific attributes. Here, male dispersal patterns and genetic structuring were examined using four Y-microsatellite loci in 186 male western grey kangaroos, Macropus fuliginosus, from throughout the species’ trans-continental distribution. In addition, 52 male grey kangaroos were examined to investigate hybridisation between M. fuliginosus and the eastern grey kangaroo, Macropus giganteus, in their region of sympatry in eastern Australia. Detected Y chromosome diversity was low, resulting from low effective male population size due to skewed sex ratios and a polygynous mating system. As expected, male dispersal was high across the range. However, the Lake Torrens–Flinders Ranges region appears to have significantly restricted male movement between eastern and central/western Australia. There was little evidence to suggest that other barriers (Nullarbor Plain and Swan River Valley) previously identified by nuclear and mitochondrial DNA marker studies restrict male movement. Hence, the admixture events previously identified may be associated with high male dispersal. Within the region of sympatry between M. fuliginosus and M. giganteus in eastern Australia, four M. giganteus individuals were found to possess M. fuliginosus Y-haplotypes. These results confirm the occurrence of hybridisation between male M. fuliginosus and female M. giganteus. Additionally, the introgression of M. fuliginosus Y-haplotypes into M. giganteus populations indicates that at least some male hybrids are fertile, despite evidence to the contrary from captive studies. This study has provided insights into the male contribution to population history, structure and hybridisation in M. fuliginosus, which were not predicted by comparisons between biparentally and maternally inherited markers. This highlights the importance of direct examination of the Y chromosome to provide novel insights into male-mediated processes, especially where the contribution of the sexes may differ.
Adult Work Commitment, Financial Stability, and Social Environment as Related to Trajectories of Marijuana Use Beginning in Adolescence
Authors: Brook Judith S. , Lee Jung Yeon , Finch Stephen J. , Seltzer Nathan , Brook David W.
Published: March 2013

Background

The objective of this study is to examine trajectories of marijuana use among African Americans and Puerto Ricans from adolescence to adulthood, with attention paid to work commitment, financial stability, drug use, and violence.

Methods

Participants ( N = 816) completed in-class questionnaires as students in the East Harlem area of New York City at the first wave and provided follow-up data at 4 additional points in time (mean ages = 14, 19, 24, 29, and 32 years). Among 816 participants, there were 60% females, 52% African American, and 48% Puerto Ricans.

Results

The chronic marijuana user trajectory group compared with the none or low, increasing, and/or moderate marijuana user trajectory group was associated with negative aspects of work commitment, financial stability, and the social environment. The chronic marijuana user group was similar to the increasing marijuana user group on work commitment and financial stability.

Conclusions

These results suggest that treating marijuana use in late adolescence may reduce difficulty in the assumption of adult roles. Because chronic marijuana users experienced the most adverse effects in each of the domains, they require more intense clinical intervention than moderate marijuana users.
An allometric relationship between mitotic spindle width, spindle length, and ploidy inCaenorhabditis elegansembryos
Authors: Hara Yuki , Kimura Akatsuki
Published: March 2013

The mitotic spindle is a diamond-shaped molecular apparatus crucial for chromosomal segregation. The regulation of spindle length is well studied, but little is known about spindle width. Previous studies suggested that the spindle can self-organize to maintain a constant aspect ratio between its length and width against physical perturbations. Here we determine the widths of metaphase spindles of various sizes observed during embryogenesis in Caenorhabditis elegans, including small spindles obtained by knocking down the tpxl-1 or spd-2 gene. The spindle width correlates well with the spindle length, but the aspect ratio between the spindle length and spindle width is not constant, indicating an allometric relationship between these parameters. We characterize how DNA quantity (ploidy) affects spindle shape by using haploid and polyploid embryos. We find that the length of the hypotenuse, which corresponds to the distance from the apex of the metaphase plate to the spindle pole, remains constant in each cell stage, regardless of ploidy. On the basis of the quantitative data, we deduce an allometric equation that describes the spindle width as a function of the length of the hypotenuse and ploidy. On the basis of this equation, we propose a force-balance model to determine the spindle width.
Mate and fuse: how yeast cells do it
Authors: Merlini Laura , Dudin Omaya , Martin Sophie G.
Published: March 2013

Many cells are able to orient themselves in a non-uniform environment by responding to localized cues. This leads to a polarized cellular response, where the cell can either grow or move towards the cue source. Fungal haploid cells secrete pheromones to signal mating, and respond by growing a mating projection towards a potential mate. Upon contact of the two partner cells, these fuse to form a diploid zygote. In this review, we present our current knowledge on the processes of mating signalling, pheromone-dependent polarized growth and cell fusion inSaccharomyces cerevisiaeandSchizosaccharomyces pombe, two highly divergent ascomycete yeast models. While the global architecture of the mating response is very similar between these two species, they differ significantly both in their mating physiologies and in the molecular connections between pheromone perception and downstream responses. The use of both yeast models helps enlighten both conserved solutions and species-specific adaptations to a general biological problem.