bluuebunny/crossref_metadata_2025 huggingface dataset:
Suicide in Bosnia and Herzegovina and the City of Sarajevo
Authors: Music Emina , Jacobsson Lars , Salander Renberg Ellinor
Published: November 2013

Background: Besides the war experience (1992–1995), Bosnia and Herzegovina (BiH) constitutes an interesting area for studies on suicidal behavior from an ethnic and religious perspective with its mixed ethnic population of Bosniaks, Serbs, and Croats. Aims: The study investigates suicide in BiH and the capital city of Sarajevo before (1985–1991) and after the war (1998–2006), with special reference to gender and ethnicity. Method: Official suicide data were gathered for the two periods with regard to gender, ethnicity, and suicide methods used. Results: No differences in suicide rates were found in BiH and Sarajevo before and after the war. The male-to-female suicide rate ratio in BiH was significantly higher after the war than before the war, with an opposite tendency seen in Sarajevo. Before and after the war, the highest and stable suicide rates were among Serbs in BiH. In Sarajevo the highest suicide rates were found among Croats after the war. Hanging was the most common suicide method used, both before and after the war, while firearms were more commonly used after the war. Poisoning was a rarely used method in both periods. Conclusion: The stable suicide rates in BiH over the pre- and postwar periods indicate no evident influence of the Bosnian war on the postwar level of suicide rates, except for women in Sarajevo. Beside this exception, the findings indicate a long-established underlying pattern in suicide rates that was not immediately changed, even by war. The study supports earlier findings that the accessibility of means influences the choice of suicide method used.
Androgen receptor-mediated apoptosis in bovine testicular induced pluripotent stem cells in response to phthalate esters
Authors: Wang S-W , Wang S S-W , Wu D-C , Lin Y-C , Ku C-C , Wu C-C , Chai C-Y , Lee J-N , Tsai E-M , Lin C-LS , Yang R-C , Ko Y-C , Yu H-S , Huo C , Chuu C-P , Murayama Y , Nakamura Y , Hashimoto S , Matsushima K , Jin C , Eckner R , Lin C-S , Saito S , Yokoyama K K
Published: November 2013

The androgen receptor (AR) has a critical role in promoting androgen-dependent and -independent apoptosis in testicular cells. However, the molecular mechanisms that underlie the ligand-independent apoptosis, including the activity of AR in testicular stem cells, are not completely understood. In the present study, we generated induced pluripotent stem cells (iPSCs) from bovine testicular cells by electroporation of octamer-binding transcription factor 4 (OCT4). The cells were supplemented with leukemia inhibitory factor and bone morphogenetic protein 4, which maintained and stabilized the expression of stemness genes and pluripotency. The iPSCs were used to assess the apoptosis activity following exposure to phthalate esters, including di (2-ethyhexyl) phthalates, di (n-butyl) phthalate, and butyl benzyl phthalate. Phthalate esters significantly reduced the expression of AR in iPSCs and induced a higher ratio of BAX/BCL-2, thereby favoring apoptosis. Phthalate esters also increased the expression of cyclin-dependent kinase inhibitor 1 (p21Cip1) in a p53-dependent manner and enhanced the transcriptional activity of p53. The forced expression of AR and knockdown of p21Cip1 led to the rescue of the phthalate-mediated apoptosis. Overall, this study suggests that testicular iPSCs are a useful system for screening the toxicity of environmental disruptors and examining their effect on the maintenance of stemness and pluripotency, as well as for identifying the iPSC signaling pathway(s) that are deregulated by these chemicals.
Deciphering unusual uncultured magnetotactic multicellular prokaryotes through genomics
Authors: Abreu Fernanda , Morillo Viviana , Nascimento Fabrícia F , Werneck Clarissa , Cantão Mauricio Egidio , Ciapina Luciane Prioli , de Almeida Luiz Gonzaga Paula , Lefèvre Christopher T , Bazylinski Dennis A , de Vasconcelos Ana Tereza Ribeiro , Lins Ulysses
Published: November 2013

Candidatus Magnetoglobus multicellularis (Ca. M. multicellularis) is a member of a group of uncultured magnetotactic prokaryotes that possesses a unique multicellular morphology. To better understand this organism’s physiology, we used a genomic approach through pyrosequencing. Genomic data analysis corroborates previous structural studies and reveals the proteins that are likely involved in multicellular morphogenesis of this microorganism. Interestingly, some detected protein sequences that might be involved in cell adhesion are homologues to phylogenetically unrelated filamentous multicellular bacteria proteins, suggesting their contribution in the early development of multicellular organization in Bacteria. Genes related to the behavior of Ca. M. multicellularis (chemo-, photo- and magnetotaxis) and its metabolic capabilities were analyzed. On the basis of the genomic–physiologic information, enrichment media were tested. One medium supported chemoorganoheterotrophic growth of Ca. M. multicellularis and allowed the microorganisms to maintain their multicellular morphology and cell cycle, confirming for the first time that the entire life cycle of the MMP occurs in a multicellular form. Because Ca. M. multicellularis has a unique multicellular life style, its cultivation is an important achievement for further studies regarding the multicellular evolution in prokaryotes.
Techniques for the Characterisation of Molecular Gels
Authors: Nebot Vicent J. , Smith David K.
Published: November 2013

Molecular gels represent a case of hierarchical self-assembly of low molecular weight compounds into well ordered fibrillar architectures through non-covalent interactions. The resulting nanomaterials have found applications in multiple fields. In order to facilitate these applications, detailed study of their self-assembly mechanisms and properties at different length scales is required. The hierarchical nature of these materials means that a wide and multidisciplinary set of techniques have been developed and applied for the fundamental study of molecular gels. Different techniques are optimal for characterising aspects of the gel on each length scale – molecular, nano, microscopic and macroscopic. The present chapter uses selected examples to describe the different techniques that have been applied so far for a complete characterization of these systems. In particular, we focus on spectroscopy for probing molecular assembly, microscopy & diffraction/scattering to probe the nanoscale structuring, and calorimetric & rheological studies to provide insight into macroscopic performance. This chapter also focuses on aspects of gel characterisation such as chirality, kinetics and solvent effects.
Molecular Gels Responsive to Physical and Chemical Stimuli
Authors: Xiong Ming , Wang Cheng , Zhang Guanxin , Zhang Deqing
Published: November 2013

In this chapter, we summarize the recent progresses in the field of stimuli-responsive gels based on low molecular weight gelators (LMWGs). The gel–solution transition can be triggered by physical stimuli (temperature, mechanical forces, ultrasound waves and UV-Vis light) or by chemical stimuli (acid–base reagents, anions and cations, neutral molecules and redox reagents). Furthermore, the potential applications of these stimuli-responsive molecular gels are discussed. In addition, challenging issues and perspectives of such stimuli-responsive gels are discussed.
Enzyme-Responsive Molecular Gels
Authors: Debnath Sisir , Ulijn Rein V.
Published: November 2013

This chapter details recent developments in the use of biocatalytic reactions to control and direct supramolecular gelation of peptide derivatives. The use of biocatalysis in this context provides a powerful approach for the development of ‘smart’ biomaterials in that it combines biological selectivity and catalytic amplification with the versatility of the bottom-up nanofabrication through dynamic self-assembly. The design rules of the self-assembly building blocks and biocatalytic switch components are discussed. Then, we will discuss a number of unique features of these systems, including the possibility of controlling mechanical properties, construction of variable structures from identical chemical components exploiting kinetically controlled systems and the defect correcting and component-selecting capabilities of the systems that operate under thermodynamic control. Applications of these biocatalytic gels are discussed in context of (intracellular) biosensing, controlled release and cell instructive materials that control and direct cell fate.
Optic and Electronic Applications of Molecular Gels
Authors: Puigmartí-Luis Josep , Amabilino David B.
Published: November 2013

Molecular gels present an ideal opportunity for the preparation of materials in which a fibre-like morphology is required because of their inherent characteristic of containing relatively well ordered supramolecular polymer chains. Molecular gels have been prepared from virtually all of the important classes of molecules that are used in optical and electronic applications, and they show that the gel route is advantageous over other states, such as crystals, because of the ease of processing and deposition on surfaces. In this respect, gels are also preferable to casting from homogeneous fluid solutions, because the role of the surface is less important. On the other hand, gels provide a unique opportunity for the preparation of hybrids and composites, and the few examples in this area suggest that new materials with unique properties could be achieved through this approach. Equally, the self-sorting or orthogonal self-assembly of molecular gels for materials preparation is likely to find application in the optics and electronics areas. Liquid-crystalline gels are shown to be interesting in their own right for display applications and the challenge of making molecule-derived aerogels for conducting and sensing applications is highlighted.
Molecular Gels as Templates for Nanostructured Materials
Authors: Kar Tanmoy , Das Prasanta Kumar
Published: November 2013

Over the past few decades generation of inorganic nanostructured materials has received increasing attention due to their potentials in diversified domains including bioseparation, imaging applications as well as in drug delivery. Inorganic materials, although diverse in composition, generally lack the structural variety characteristic of supramolecular and other organic structures. In this regard, various supramolecular self-assemblies formed by the small organic molecules have been employed as templates for the generation of novel inorganic nanostructures that are otherwise unattainable. This chapter depicts the transcription of low molecular weight gels into discrete, inorganic structures (silica, TiO2, CdS and many more). Moreover, the self-assembled fibrillar networks of supramolecular gels have also been used as a template for the development of inorganic–organic hybrid materials from the combination of gels with nanoparticles of different origins. The supramolecular gel matrix has been used to synthesize and immobilize nanoparticles by modulating the gel structure with appropriated functionality. The present chapter also highlights the significant research progress of gel-nanocomposites and emphasizes the recent advances in their synthesis, improved properties/features and applications in different fields.
A real-time cell-electronic sensing method for comparative analysis of toxicity of water contaminants
Authors: Du Haiying , Li Jinhua , Moe Birget , McGuigan Claire F. , Li Xing-Fang
Published: November 2013

Real time cell sensing of chemical toxicity.
Loss of TRPML1 promotes production of reactive oxygen species: is oxidative damage a factor in mucolipidosis type IV?
Authors: Coblentz Jessica , St. Croix Claudette , Kiselyov Kirill
Published: November 2013

TRPML1 (transient receptor potential mucolipin 1) is a lysosomal ion channel permeable to cations, including Fe2+. Mutations in MCOLN1, the gene coding for TRPML1, cause the LSD (lysosomal storage disease) MLIV (mucolipidosis type IV). The role of TRPML1 in the cell is disputed and the mechanisms of cell deterioration in MLIV are unclear. The demonstration of Fe2+ buildup in MLIV cells raised the possibility that TRPML1 dissipates lysosomal Fe2+ and prevents its accumulation. Since Fe2+ catalyses the production of ROS (reactive oxygen species), we set out to test whether or not the loss of TRPML1 promotes ROS production by Fe2+ trapped in lysosomes. Our data show that RPE1 (retinal pigmented epithelial 1) cells develop a punctate mitochondrial phenotype within 48 h of siRNA-induced TRPML1-KD (knockdown). This mitochondrial fragmentation was aggravated by Fe2+ exposure, but was reversed by incubation with the ROS chelator α-Toc (α-tocopherol). The exposure of TRPML1-KD cells to Fe2+ led to loss of ΔΨm (mitochondrial membrane potential), ROS buildup, lipid peroxidation and increased transcription of genes responsive to cytotoxic oxidative stress in TRPML1-KD cells. These data suggest that TRPML1 redistributes Fe2+ between the lysosomes and the cytoplasm. Fe2+ buildup caused by TRPML1 loss potentiates ROS production and leads to mitochondrial deterioration. Beyond suggesting a new model for MLIV pathogenesis, these data show that TRPML1's role in the cell extends outside lysosomes.
Valsartan slows the progression of diabetic nephropathy in db/db mice via a reduction in podocyte injury, and renal oxidative stress and inflammation
Authors: Zhou Guangyu , Cheung Alfred K. , Liu Xia , Huang Yufeng
Published: November 2013

Higher doses of AngII (angiotensin II) blockers are intended to optimize albuminuria reduction rather than for blood pressure control in chronic kidney disease. However, the long-term renoprotection of high-dose AngII blockers has yet to be defined. The present study sought to determine whether doses of ARB (AngII receptor blocker) that maximally reduce proteinuria could slow the progression of glomerulosclerosis in the uninephrectomized db/db mouse, a model of Type 2 diabetes. Untreated uninephrectomized db/db mice had normal blood pressure, but developed progressive albuminuria and mesangial matrix expansion between 18 and 22 weeks of age, which was associated with increased renal expression of TGFβ1 (transforming growth factor β1), PAI-1 (plasminogen-activator inhibitor-1), type IV collagen and FN (fibronectin). Treatment with valsartan in the drinking water of db/db mice from 18 to 22 weeks of age, at a dose that was determined previously to maximally reduce proteinuria, prevented the increases in albuminuria and the markers of renal fibrosis seen in untreated db/db mice. In addition, WT-1 (Wilms tumour protein-1)-immunopositive podocyte numbers were found to be lower in the untreated glomeruli of mice with diabetes. The expression of podocin and nephrin were continually decreased in mice with diabetes between 18 and 22 weeks of age. These changes are indicative of podocyte injury and the administration of valsartan ameliorated them substantially. Renal expression of TNFα (tumour necrosis factor α), MCP-1 (monocyte chemoattractant protein-1), Nox2 (NADPH oxidase 2), p22phox and p47phox and urine TBARS (thiobarbituric acid-reacting substance) levels, the markers of renal inflammation and oxidative stress, were increased during disease progression in mice with diabetes. Valsartan treatment was shown to reduce these markers. Thus high doses of valsartan not only reduce albuminuria maximally, but also halt the progression of the glomerulosclerosis resulting from Type 2 diabetes via a reduction in podocyte injury and renal oxidative stress and inflammation.
Determination of multilayer thicknesses of GaAs/AlAs
superlattice by grazing incidence X-ray reflectivity
Authors: Ren L.L. , Gao H.F. , Gao S.T. , Liu J.J. , Zhang W.
Published: November 2013

The grazing incidence X-ray reflectivity is used to determine the multilayer thickness of
GaAs/AlAs supperlattice. The measurement process includes the fitting model and the
measurement conditions (different powers of 45 kV × 40 mA, 40 kV × 40 mA and 35 kV × 40
mA, different step sizes of 0.005°, 0.008° and 0.010°,
and different times per step of 1 s, 2 s, 3 s). In order to obtain the valid measurement
process, the combined standard deviation is used as the normal of the fitting results
selection. As a result, the measurement condition of 0.008° step size and 2 s
time per step with the power 40 kV × 40 mA is selectable with the operation stability of
facilities and smaller error.
Shielding effectiveness measurements and uncertainty estimation
for textiles by a VNA-based free space transmission method
Authors: Patel S.M. , Patel K. , Negi P.S. , Ojha V.N.
Published: November 2013

A free-space transmission method has been used for reliable shielding effectiveness
measurement of the easily available textile materials. Textiles with three different yarn
densities were studied for their shielding effectiveness with the help of a vector network
analyzer and laboratory calibrated two X-band horn antennas. The expressions of
uncertainty estimation have been derived in accordance with the present free-space
measurement setup for the calculated SE values. The measurements have shown that an
electromagnetic energy can be maximum shielded up to 16.24 dB with measurement uncertainty
less than 0.21 dB in 8.2 to 12.4 GHz range by a 160.85 μm textile. Thus,
a thin textile with a high density can have higher shielding and this property mainly
depends on its intrinsic structure, frequency range and thickness. This study promises the
potential applications of such materials as a very cost effective shielding material at
microwave frequencies with some modifications.
A compact system for generating extreme pressures and temperatures: An application of laser-heated diamond anvil cell to inelastic X-ray scattering
Authors: Fukui Hiroshi , Sakai Takeshi , Sakamaki Tatsuya , Kamada Seiji , Takahashi Suguru , Ohtani Eiji , Baron Alfred Q. R.
Published: November 2013

A compact system for generating extreme pressures and temperatures was developed for versatile experiments based on laser-heated diamond anvil cell technique. This system has been used for inelastic X-ray scattering measurements for iron.
Favorable adsorption of capped amino acids on graphene substrate driven by desolvation effect
Authors: Dragneva N. , Floriano W. B. , Stauffer D. , Mawhinney R. C. , Fanchini G. , Rubel O.
Published: November 2013

The use of graphene-based nanomaterials is being explored in the context of various biomedical applications. Here, we performed a molecular dynamics simulation of individual amino acids on graphene utilizing an empirical force field potential (Amber03). The accuracy of our force field method was verified by modeling the adsorption of amino acids on graphene in vacuum. These results are in excellent agreement with those calculated using ab initio methods. Our study shows that graphene exhibits bioactive properties in spite of the fact that the interaction between graphene and amino acids in a water environment is significantly weaker as compared to that in vacuum. Furthermore, the adsorption characteristics of capped and uncapped amino acids are significantly different from each other due to the desolvation effect. Finally, we conclude that when assessing protein-surface interactions based on adsorption of single amino acids, the minimum requirement is to use capped amino acids as they mimic residues as part of a peptide chain.
Block correlated second order perturbation theory with a generalized valence bond reference function
Authors: Xu Enhua , Li Shuhua
Published: November 2013

The block correlated second-order perturbation theory with a generalized valence bond (GVB) reference (GVB-BCPT2) is proposed. In this approach, each geminal in the GVB reference is considered as a “multi-orbital” block (a subset of spin orbitals), and each occupied or virtual spin orbital is also taken as a single block. The zeroth-order Hamiltonian is set to be the summation of the individual Hamiltonians of all blocks (with explicit two-electron operators within each geminal) so that the GVB reference function and all excited configuration functions are its eigenfunctions. The GVB-BCPT2 energy can be directly obtained without iteration, just like the second order Møller–Plesset perturbation method (MP2), both of which are size consistent. We have applied this GVB-BCPT2 method to investigate the equilibrium distances and spectroscopic constants of 7 diatomic molecules, conformational energy differences of 8 small molecules, and bond-breaking potential energy profiles in 3 systems. GVB-BCPT2 is demonstrated to have noticeably better performance than MP2 for systems with significant multi-reference character, and provide reasonably accurate results for some systems with large active spaces, which are beyond the capability of all CASSCF-based methods.
Quantized Hamiltonian dynamics captures the low-temperature regime of charge transport in molecular crystals
Authors: Wang Linjun , Akimov Alexey V. , Chen Liping , Prezhdo Oleg V.
Published: November 2013

The quantized Hamiltonian dynamics (QHD) theory provides a hierarchy of approximations to quantum dynamics in the Heisenberg representation. We apply the first-order QHD to study charge transport in molecular crystals and find that the obtained equations of motion coincide with the Ehrenfest theory, which is the most widely used mixed quantum-classical approach. Quantum initial conditions required for the QHD variables make the dynamics surpass Ehrenfest. Most importantly, the first-order QHD already captures the low-temperature regime of charge transport, as observed experimentally. We expect that simple extensions to higher-order QHDs can efficiently represent other quantum effects, such as phonon zero-point energy and loss of coherence in the electronic subsystem caused by phonons.
Vortex line density in counterflowing He II with laminar and turbulent normal fluid velocity profiles
Authors: Baggaley A. W. , Laizet S.
Published: November 2013

Superfluid helium is an intimate mixture of a viscous normal fluid, with continuous vorticity, and an inviscid superfluid, where vorticity is constrained to thin, stable topological defects. One mechanism to generate turbulence in this system is through the application of a heat flux, so-called thermal counterflow. Of particular interest is how turbulence in the superfluid responds to both a laminar and turbulent normal fluid in the presence of walls. We model superfluid vortex lines as reconnecting space curves with fixed circulation, and consider both laminar (Poiseuille) and turbulent normal fluid flows in a channel configuration. Using high resolution numerical simulations we show that turbulence in the normal fluid sustains a notably higher vortex line density than a laminar flow with the same mean flow rate. We examine Vinen's relation, \documentclass[12pt]{minimal}\begin{document}$\sqrt{L}=\gamma v_{ns}$\end{document}L=γvns, between the steady state vortex line density L and the counterflow velocity vns. Our results support the hypothesis that transition to turbulence in the normal fluid is responsible for the TI to TII transition. We also consider the spectral properties of fluctuations of the superfluid vortices, which show a good agreement with previous experimental results.
Theory of polymer-dispersed cholesteric liquid crystals
Authors: Matsuyama Akihiko
Published: November 2013

A mean field theory is presented to describe cholesteric phases in mixtures of a polymer and a cholesteric liquid crystal. Taking into account an anisotropic coupling between a polymer and a liquid crystal, we examine the helical pitch, twist elastic constant, and phase separations. Analytical expressions of the helical pitch of a cholesteric phase and the twist elastic constant are derived as a function of the orientational order parameters of a polymer and a liquid crystal and two intermolecular interaction parameters. We also find isotropic-cholesteric, cholesteric-cholesteric phase separations, and polymer-induced cholesteric phase on the temperature-concentration plane. We demonstrate that an anisotropic coupling between a polymer and a liquid crystal can stabilize a cholesteric phase in the mixtures. Our theory can also apply to mixtures of a nematic liquid crystal and a chiral dopant. We discuss the helical twisting power, which depends on temperature, concentration, and orientational order parameters. It is shown that our theory can qualitatively explain experimental observations.
Capillary instability of a viscous liquid thread in a cylindrical tube
Authors: Wang Qiming
Published: November 2013

We study axisymmetric breakup and drop formation of a liquid thread confined in a cylindrical tube by using a long wave model. The limit with large viscosity contrast is investigated, consisting of a highly viscous core and a less viscous annulus. Satellite drop formation near pinching is found to be dependent on the location of the tube wall, while inertia is found to have little effect. It is also shown that main drops tend to form so called “plug with collar” structures when the tube wall is close to the thread interface so that rings of fluid are trapped inside the plugs. Finally, our numerical simulations show that a double cone structure occurs on the breakup and the cone angles are fixed, even though self-similar solutions may not exist.
Curvature effect on tearing modes in presence of neoclassical friction
Authors: Maget Patrick , Mellet Nicolas , Lütjens Hinrich , Meshcheriakov Dmytro , Garbet Xavier
Published: November 2013

Neoclassical physics (here associated to the poloidal variation of the magnetic field strength along field lines in a tokamak) is well known for driving self-generated plasma current and nonlinear magnetic islands associated to it in high performance, ITER relevant plasma discharges. It is demonstrated that the neoclassical friction between a magnetic perturbation and plasma flow already impacts magnetic islands in the linear regime, by inducing a weakening of curvature stabilization for tearing modes. This conclusion holds in particular for regimes where convection is influencing the pressure dynamics, as shown using a simple analytical model and confirmed in full Magneto-Hydro-Dynamics simulations.
The stability of a static liquid column pulled out of an infinite pool
Authors: Benilov E. S. , Cummins C. P.
Published: November 2013

We study the stability of a static liquid column rising from an infinite pool, with its top attached to a horizontal plate suspended at a certain height above the pool's surface. Two different models are employed for the column's contact line. Model 1 assumes that the contact angle always equals Young's equilibrium value. Model 2 assumes a functional dependence between the contact angle and the velocity of the contact line, and we argue that, if this dependence involves a hysteresis interval, linear perturbations cannot move the contact line. It is shown that, within the framework of Model 1, all liquid columns are unstable. In Model 2, both stable and unstable columns exist (the former have larger contact angles θ and/or larger heights H). For Model 2, the marginal stability curve on the (θ, H)-plane is computed. The mathematical results obtained imply that, if the plate to which a stable liquid column is attached is slowly lifted up, the column's contact line remains pinned while the contact angle is decreasing. Once it reaches the lower boundary of the hysteresis interval, the column breaks down.
An ab initio study on compressibility of Al-containing MAX-phase carbides
Authors: Bai Yuelei , He Xiaodong , Wang Rongguo , Zhu Chuncheng
Published: November 2013

The compressibility of Al-containing MAX carbides was investigated in details using first-principle calculations based on density functional theory. The bond stiffness and bond angle as a function of pressure were examined. The M-Al bond stiffness is about 1/3–1/2 of M-C bond stiffness. The M-C bond close to Al atoms has the highest bond stiffness in M3AlC2 and M4AlC3 phases, with the similar bond stiffness of the other two bonds in the latter. Generally, the bond stiffness of the strongest M-C bond increases with increasing VEC (Valence Electron Concentration), which also affects the bond stiffness of other bonds. Of most importance, the bulk moduli are 0.256 of the mean bond stiffness for three series. With increasing pressure, M-Al bond angle increases, but M-C bond angles decreases, which indicates that M-Al and M-C bonds shift towards basal plane and along c-axis, respectively. As a result, the compressibility becomes more difficult along c-axis than a-axis. Some abnormal phenomena in the compressibility of Al-containing Mn+1AlXn phases with VEC = 6 are attributed to the thermodynamical instability of these compounds.
Observation of rebirth of metallic paths during resistance switching of metal nanowire
Authors: Horiba K. , Fujiwara K. , Nagamura N. , Toyoda S. , Kumigashira H. , Oshima M. , Takagi H.
Published: November 2013

To clarify the mechanism of resistance-switching phenomena, we have investigated the change in the electronic structure of a Ni nanowire device during resistance-switching operations using scanning photoelectron microscopy techniques. We directly observed the disappearance of density of state (DOS) at the Fermi level (EF) in a high-resistance state and recovery of a finite DOS at EF in a low-resistance state. These results are direct evidence that the Ni nanowire is fully oxidized after switching to the high-resistance state and that Ni-metal conductive paths in the oxidized nanowire are recovered in the low-resistance state.
Atomic scattering spectroscopy for determination of the polarity of semipolar AlN grown on ZnO
Authors: Kobayashi Atsushi , Ueno Kohei , Ohta Jitsuo , Oshima Masaharu , Fujioka Hiroshi
Published: November 2013

Determination of the polarity of insulating semipolar AlN layers was achieved via atomic scattering spectroscopy. The back scattering of neutralized He atoms on AlN surfaces revealed the atomic alignment of the topmost layers of semipolar AlN and the ZnO substrate. Pole figures of the scattering intensity were used to readily determine the polarity of these wurtzite-type semipolar materials. In addition, we found that +R-plane AlN epitaxially grows on −R-plane ZnO, indicating that the polarity flips at the semipolar AlN/ZnO interface. This polarity flipping is possibly explained by the appearance of −c and m-faces on the −R ZnO surfaces, which was also revealed by atomic scattering spectroscopy.
From polarization-dependent to polarization-independent terahertz meta-foils
Authors: Wu Jianfeng , Moser Herbert O. , Xu Su , Banas Agnieszka , Banas Krzysztof , Chen Hongsheng , Breese Mark B. H.
Published: November 2013

THz meta-foils have been introduced as an electromagnetic metamaterial, and their properties depend only on the geometric structure and the metal. Upon showing that conventional parallel-string meta-foils exhibit a strong polarization dependence, we propose and manufacture crossed meta-foils and demonstrate experimentally and numerically that their transmission spectra are polarization-independent. In this way, polarization-independent, all-metal, self-supported, free-standing, left-handed metamaterials are achieved, which provide a versatile platform for developing practical applications of metamaterials.
Free electron gas primary thermometer: The bipolar junction transistor
Authors: Mimila-Arroyo J.
Published: November 2013

The temperature of a bipolar transistor is extracted probing its carrier energy distribution through its collector current, obtained under appropriate polarization conditions, following a rigorous mathematical method. The obtained temperature is independent of the transistor physical properties as current gain, structure (Homo-junction or hetero-junction), and geometrical parameters, resulting to be a primary thermometer. This proposition has been tested using off the shelf silicon transistors at thermal equilibrium with water at its triple point, the transistor temperature values obtained involve an uncertainty of a few milli-Kelvin. This proposition has been successfully tested in the temperature range of 77–450 K.
Relationship between Cu2ZnSnS4 quasi donor-acceptor pair density and solar cell efficiency
Authors: Gershon Talia , Shin Byungha , Gokmen Tayfun , Lu Siyuan , Bojarczuk Nestor , Guha Supratik
Published: November 2013

We examined the 4 K photoluminescence spectra of over a dozen Cu2ZnSnS4 films and eight devices. We show that samples deficient in zinc show on average a higher quasi donor-acceptor pair (QDAP) density. However, the QDAP density in samples with the same metal composition also varies widely. Devices prepared with similar metal compositions show different open-circuit voltages and fill factors. These metrics are correlated with the concentration of QDAPs in the absorbers. One additional device with insufficient zinc showed the empirically observed low-efficiency expected for this composition. This sample also showed the highest quasi donor-acceptor pair density of all the devices measured.
Direct observation of ultrafast surface transport of laser-driven fast electrons in a solid target
Authors: Singh Prashant Kumar , Cui Y. Q. , Chatterjee Gourab , Adak Amitava , Wang W. M. , Ahmed Saima , Lad Amit D. , Sheng Z. M. , Ravindra Kumar G.
Published: November 2013

We demonstrate rapid spread of surface ionization on a glass target excited by an intense, ultrashort laser pulse at an intensity of 3 × 1017 W cm−2. Time- and space-resolved reflectivity of the target surface indicates that the initial plasma region created by the pump pulse expands at c/7. The measured quasi-static megagauss magnetic field is found to expand in a manner very similar to that of surface ionization. Two-dimensional particle-in-cell simulations reproduce measurements of surface ionization and magnetic fields. Both the experiment and simulation convincingly demonstrate the role of self-induced electric and magnetic fields in confining fast electrons along the target-vacuum interface.
The influence of self-assembly behavior of nanoparticles on the dielectric polymer composites
Authors: Lu Xin , Li Weiping , Wang Tingting , Jiang Long , Luo Laihui , Hua Dayin , Zhu Yuejin
Published: November 2013

To clearify the influence of the distribution of the conductive nanoparticles on the dielectric properties of the corresponding polymer composites, the microstructure and dielectric character of the composites based on the oleic acid modified ferroferric oxide and polyvinylidene fluoride (PVDF) polymer have been studied experimentally. It is found that these composites exhibit a normal percolative phase transition over the filler content from insulator to conductor, consistent with the classical percolation theory. However, when the percentage of fillers is at a certain value which is below the percolation threshold, these nanoparticles can assemble into a special porous structure in the PVDF matrix, associated with the enhancement of dielectric constant at low frequency. In addition, the controllable dispersion of conducting nanoparticles in a polymer matrix can prevent premature agglomeration at low filling fractions and avoid the appearance of anomalously early percolation. Therefore, the self-assembly behavior of nanoparticles can be beneficial to preparation of the high dielectric constant and low loss composites for the application of electric energy storage.
Structure of a burrow of the northern hopping-mouse, Notomys aquilo, and its surface signs on Groote Eylandt
Authors: Ward Simon J.
Published: November 2013

Identification of surface signs of burrows is becoming central to monitoring programs for the northern hopping-mouse. A burrow system was excavated in a sandy woodland area of Groote Eylandt to confirm it was used by northern hopping-mice, describe its structure, and relate structure to surface signs. The burrow was T-shaped, ~2 m long and wide, and connected to four vertical shafts leading to pop-hole-entrances/exits. The depth of the burrow was constrained by a rocky layer ~0.5 m below the surface. It was occupied by five hopping-mice, three of which were caught. The burrow systems dug by northern hopping-mice are more complex and extensive than those of delicate mice, Pseudomys delicatulus, and the major surface signs (spoil heaps or mounds) left by northern hopping-mice are unmarked by entrances or tracks, whereas those of delicate mice are marked by an entrance and trackways (if occupied).
Quantum-chemical Ab Initio Calculations on the Donor–Acceptor Complex Pyridine–Borabenzene (C5H5N–BC5H5)
Authors: Mbarki Mohammed , Oettinghaus Marc , Raabe Gerhard
Published: November 2013

The adduct of borabenzene (C5H5B) and pyridine (C5H5N) was studied by means of quantum-chemical ab initio and time-dependent density functional theory calculations at different levels of theory. In the fully optimized structure (MP2/6-311++G**) of the free donor–acceptor complex (C2), the C–B–C angle amounts to 120.6°. The planes of the two aromatic rings enclose a torsion angle of ~40° with a barrier to rotation about the B–N bond of less than 3 kcal mol–1 (1 kcal mol–1 = 4.186 kJ mol–1). The highest computational level applied in this study (complete basis set limit, coupled cluster with single and double excitations (CCSD)) results in an energy associated with the reaction of borabenzene with pyridine of –52.2 kcal mol–1. Natural bond orbital analyses were performed to study the bond between the borabenzene and the pyridine unit of the adduct. The UV-vis spectrum of the adduct was calculated employing time-dependent density functional theory methods and the symmetry-adapted cluster-configuration interaction method. Our calculated electronic excitation spectrum of the pyridine adduct as well as its spectrum of the normal modes qualitatively reproduce the characteristic features of the IR and the UV-vis spectra described by experimentalists and thus allows assignment of the observed absorption bands, which in part agree with those by other authors.
Bird use of almond plantations: implications for conservation and production
Authors: Luck Gary W. , Triplett Shannon , Spooner Peter G.
Published: November 2013

Context Farmland crops may suffer damage from native animals, but also provide a critical resource during times of food scarcity. We know little about bird use of almond crops. Aims To examine factors influencing temporal and spatial variation in the use of almond crops in north-western Victoria by bird species, including the threatened regent parrot (Polytelis anthopeplus), and to record levels of crop damage. Methods We measured bird occurrence in 15 transects during the almond-growing season of 2009/10, and 32 transects during 2010/11. Crop-damage assessments were conducted in 2010/11. Spatio-temporal variation in bird occurrence was related to seasonal factors, landscape variables and bird-control activities. Key results Significantly more regent parrots and small parrots (e.g. Platycercus elegans and Psephotus haematonotus) were recorded in almond plantations in 2009/10 than in 2010/11. Rainfall and wheat production was much higher in 2010/11, and we hypothesise that the availability of alternative foods reduced parrot dependence on almonds. Regent parrot occurrence did not differ across months within a season, but more small parrots were recorded during almond nut maturity. Regent parrots appeared to prefer locations where almond crops abutted native vegetation, but only during 2009/10, a dry year with likely limited food availability. Small parrots occurred more often in crops close to riverine vegetation and distant from farm offices. Nut damage was generally low, with only 7 of 32 transects sustaining >4% total damage, but damage assessments were conducted during a season of high rainfall, with likely greater availability of alternative food. Percentage damage was significantly correlated with the number of regent and small parrots. Shooting activity did not deter birds from using almond crops. Conclusions Parrots appear to rely more on almond crops for food when environmental conditions limit other food resources. A key strategy for managing bird impacts on almonds while supporting species conservation is to provide decoy crops of preferred native plants. Implications Rapid loss of almond plantations may lead to population declines in the threatened regent parrot if the availability of alternative food is not simultaneously increased. The role of production land uses in supporting native birds needs to be recognised by conservation management agencies.
Nuclear interferon-inducible protein 16 promotes silencing of herpesviral and transfected DNA
Authors: Orzalli Megan H. , Conwell Sara E. , Berrios Christian , DeCaprio James A. , Knipe David M.
Published: November 2013

Significance

Cells have evolved mechanisms to silence foreign DNA to prevent the expression of foreign genes within them. In mammalian cells, this involves the assembly of heterochromatin on foreign DNAs such as viral or transfected DNA. Herpesviruses have evolved strategies to counteract these host mechanisms to express their own genes. Herein we demonstrate that the nuclear DNA sensor IFN-inducible protein 16 (IFI16) is involved in the host silencing response to foreign DNA. IFI16 promotes the assembly of heterochromatin on herpesviral DNA and inhibition of viral immediate–early gene expression and replication. This silencing effect is also observed on transfected plasmid DNAs. Therefore, our results indicate that IFI16 is broadly involved in the cellular response to foreign DNA.
A symmetric homotopy and hybrid polynomial system solving method for mixed trigonometric polynomial systems
Authors: Dong Bo , Yu Bo , Yu Yan
Published: November 2013

A mixed trigonometric polynomial system, which rather frequently occurs in applications, is a polynomial system where every monomial is a mixture of some variables and sine and cosine functions applied to the other variables. Polynomial systems transformed from the mixed trigonometric polynomial systems have a special structure. Based on this structure, a hybrid polynomial system solving method, which is more efficient than random product homotopy method and polyhedral homotopy method in solving this class of systems, has been presented. Furthermore, the transformed polynomial system has an inherent partially symmetric structure, which cannot be adequately exploited to reduce the computation by the existing methods for solving polynomial systems. In this paper, a symmetric homotopy is constructed and, combining homotopy methods, decomposition, and elimination techniques, an efficient symbolic-numerical method for solving this class of polynomial systems is presented. Preservation of the symmetric structure assures us that only part of the homotopy paths have to be traced, and more important, the computation work can be reduced due to the existence of the inconsistent subsystems, which need not to be solved at all. Exploiting the new hybrid method, some problems from the literature and a challenging practical problem, which cannot be solved by the existing methods, are resolved. Numerical results show that our method has an advantage over the polyhedral homotopy method, hybrid method and regeneration method, which are considered as the state-of-art numerical methods for solving highly deficient polynomial systems of high dimension.
The protein kinase Sch9 is a key regulator of sphingolipid metabolism inSaccharomyces cerevisiae
Authors: Swinnen Erwin , Wilms Tobias , Idkowiak-Baldys Jolanta , Smets Bart , De Snijder Pepijn , Accardo Sabina , Ghillebert Ruben , Thevissen Karin , Cammue Bruno , De Vos Dirk , Bielawski Jacek , Hannun Yusuf A. , Winderickx Joris
Published: November 2013

The Saccharomyces cerevisiae protein kinase Sch9 is an in vitro and in vivo effector of sphingolipid signaling. This study examines the link between Sch9 and sphingolipid metabolism in S. cerevisiae in vivo based on the observation that the sch9Δ mutant displays altered sensitivity to different inhibitors of sphingolipid metabolism, namely myriocin and aureobasidin A. Sphingolipid profiling indicates that sch9Δ cells have increased levels of long-chain bases and long-chain base-1 phosphates, decreased levels of several species of (phyto)ceramides, and altered ratios of complex sphingolipids. We show that the target of rapamycin complex 1–Sch9 signaling pathway functions to repress the expression of the ceramidase genes YDC1 and YPC1, thereby revealing, for the first time in yeast, a nutrient-dependent transcriptional mechanism involved in the regulation of sphingolipid metabolism. In addition, we establish that Sch9 affects the activity of the inositol phosphosphingolipid phospholipase C, Isc1, which is required for ceramide production by hydrolysis of complex sphingolipids. Given that sphingolipid metabolites play a crucial role in the regulation of stress tolerance and longevity of yeast cells, our data provide a model in which Sch9 regulates the latter phenotypes by acting not only as an effector but also as a regulator of sphingolipid metabolism.
A conserved flagella-associated protein inChlamydomonas, FAP234, is essential for axonemal localization of tubulin polyglutamylase TTLL9
Authors: Kubo Tomohiro , Yanagisawa Haru-aki , Liu Zhongmei , Shibuya Rie , Hirono Masafumi , Kamiya Ritsu
Published: November 2013

Tubulin undergoes various posttranslational modifications, including polyglutamylation, which is catalyzed by enzymes belonging to the tubulin tyrosine ligase–like protein (TTLL) family. A previously isolated Chlamydomonas reinhardtii mutant, tpg1, carries a mutation in a gene encoding a homologue of mammalian TTLL9 and displays lowered motility because of decreased polyglutamylation of axonemal tubulin. Here we identify a novel tpg1-like mutant, tpg2, which carries a mutation in the gene encoding FAP234, a flagella-associated protein of unknown function. Immunoprecipitation and sucrose density gradient centrifugation experiments show that FAP234 and TTLL9 form a complex. The mutant tpg1 retains FAP234 in the cell body and flagellar matrix but lacks it in the axoneme. In contrast, tpg2 lacks both TTLL9 and FAP234 in all fractions. In fla10, a temperature-sensitive mutant deficient in intraflagellar transport (IFT), both TTLL9 and FAP234 are lost from the flagellum at nonpermissive temperatures. These and other results suggest that FAP234 functions in stabilization and IFT-dependent transport of TTLL9. Both TTLL9 and FAP234 are conserved in most ciliated organisms. We propose that they constitute a polyglutamylation complex specialized for regulation of ciliary motility.
Cadherin-6B is proteolytically processed during epithelial-to-mesenchymal transitions of the cranial neural crest
Authors: Schiffmacher Andrew T. , Padmanabhan Rangarajan , Jhingory Sharon , Taneyhill Lisa A.
Published: November 2013

The epithelial-to-mesenchymal transition (EMT) is a highly coordinated process underlying both development and disease. Premigratory neural crest cells undergo EMT, migrate away from the neural tube, and differentiate into diverse cell types during vertebrate embryogenesis. Adherens junction disassembly within premigratory neural crest cells is one component of EMT and, in chick cranial neural crest cells, involves cadherin-6B (Cad6B) down-regulation. Whereas Cad6B transcription is repressed by Snail2, the rapid loss of Cad6B protein during EMT is suggestive of posttranslational mechanisms that promote Cad6B turnover. For the first time in vivo, we demonstrate Cad6B proteolysis during neural crest cell EMT, which generates a Cad6B N-terminal fragment (NTF) and two C-terminal fragments (CTF1/2). Coexpression of relevant proteases with Cad6B in vitro shows that a disintegrin and metalloproteinases (ADAMs) ADAM10 and ADAM19, together with γ-secretase, cleave Cad6B to produce the NTF and CTFs previously observed in vivo. Of importance, both ADAMs and γ-secretase are expressed in the appropriate spatiotemporal pattern in vivo to proteolytically process Cad6B. Overexpression or depletion of either ADAM within premigratory neural crest cells prematurely reduces or maintains Cad6B, respectively. Collectively these results suggest a dual mechanism for Cad6B proteolysis involving two ADAMs, along with γ-secretase, during cranial neural crest cell EMT.