bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamics of peptide dimer formation
Authors: Church Matthew S. , Ferry Christine E. , van Giessen Alan E.
Published: June 2012

The Replica Exchange Statistical Temperature Molecular Dynamics algorithm is used to study the equilibrium properties of a peptide monomer and dimer and the thermodynamics of peptide dimer formation. The simulation data are analyzed by the Statistical Temperature Weighted Histogram Analysis Method. Each 10-residue peptide is represented by a coarse-grained model with hydrophobic side chains and has an α-helix as its minimum energy configuration. It is shown that the configurational behavior of the dimer can be divided into four regions as the temperature increases: two folded peptides; one folded and one unfolded peptide; two unfolded peptides; and two spatially separated peptides. Two important phenomena are discussed: in the dimer, one peptide unfolds at a lower temperature than the isolated monomer and the other peptide unfolds at a higher temperature than the isolated monomer. In addition, in the temperature region where one peptide is folded and the other unfolded, the unfolded peptide adopts an extended structure that minimizes the overall surface area of the aggregate. It is suggested that combination of destabilization due to aggregation and the resulting extended configuration of the destabilized peptide could have implications for nucleating β-sheet structures and the ultimate formation of fibrils.
From strong van der Waals complexes to hydrogen bonding: From CO⋯H2O to CS⋯H2O and SiO⋯H2O complexes
Authors: Zhang Yan , Hollman David S. , Schaeffer Henry F.
Published: June 2012

Structures and interaction energies of complexes valence isoelectronic to the important CO⋯H2O complex, namely SiO⋯H2O and CS⋯H2O, have been studied for the first time using high-level ab initio methods. Although CO, SiO, and CS are valence isoelectronic, the structures of their complexes with water differ significantly, owing partially to their widely varied dipole moments. The predicted dissociation energies D0 are 1.8 (CO⋯H2O), 2.7 (CS⋯H2O), and 4.9 (SiO⋯H2O) kcal/mol. The implications of these results have been examined in light of the dipole moments of the separate moieties and current concepts of hydrogen bonding. It is hoped that the present results will spark additional interest in these complexes and in the general non-covalent paradigms they represent.
Theoretical study of the spectroscopically relevant parameters for the detection of HNPq and HPNq (q = 0, +1, −1) in the gas phase
Authors: Hochlaf Majdi , Linguerri Roberto , Dalal Shakeel S. , Francisco Joseph S.
Published: June 2012

High level ab initio electronic structure calculations at different levels of theory have been performed on HNP and HPN neutrals, anions, and cations. This includes standard coupled cluster CCSD(T) level with augmented correlation-consistent basis sets, internally contacted multi-reference configuration interaction, and the newly developed CCSD(T)-F12 methods in connection with the explicitly correlated basis sets. Core–valence correction and scalar relativistic effects were examined. We present optimized equilibrium geometries, harmonic vibrational frequencies, rotational constants, adiabatic ionization energies, electron affinities, vertical detachment energies, and relative energies. In addition, the three-dimensional potential energy surfaces of HNP−1,0,+1 and of HPN−1,0,+1 were generated at the (R)CCSD(T)-F12b/cc-pVTZ-F12 level. The anharmonic terms and fundamentals were derived using second order perturbation theory. For HNP, our best estimate for the adiabatic ionization energy is 7.31 eV, for the adiabatic electron affinity is 0.47 eV. The higher energy isomer, HPN, is 23.23 kcal/mol above HNP. HPN possesses a rather large adiabatic electron affinity of 1.62 eV. The intramolecular isomerization pathways were computed. Our calculations show that HNP− to HPN− reaction is subject to electron detachment.
Accurate theoretical study of PSq (q = 0,+1,−1) in the gas phase
Authors: Yaghlane Saida Ben , Francisco Joseph S. , Hochlaf Majdi
Published: June 2012

Highly correlated ab initio methods were used in order to generate the potential energy curves and spin-orbit couplings of electronic ground and excited states of PS and PS+. We also computed those of the bound parts of the electronic states of the PS− anion. We used standard coupled cluster CCSD(T) level with augmented correlation-consistent basis sets, internally contacted multi-reference configuration interaction, and the newly developed CCSD(T)-F12 methods in connection with the explicitly correlated basis sets. Core-valence correction and scalar relativistic effects were examined. Our data consist of a set of spectroscopic parameters (equilibrium geometries, harmonic vibrational frequencies, rotational constants, spin-orbit, and spin-spin constants), adiabatic ionization energies, and electron affinities. For the low laying electronic states, our calculations are consistent with previous works whereas the high excited states present rather different shapes. Based on these new computations, the earlier ultraviolet bands of PS and PS+ were reassigned. For PS− and in addition to the already known anionic three bound electronic states (i.e., X3Σ−, 1Δ, and 11Σ+), our calculations show that the 1Σ−, 3Σ+, and the 3Δ states are energetically below their quartet parent neutral state (a4Π). The depletion of the J = 3 component of PS−(3Δ) will mainly occur via weak interactions with the electron continuum wave.
Magnetic and electronic properties of α-graphyne nanoribbons
Authors: Yue Qu , Chang Shengli , Kang Jun , Tan Jichun , Qin Shiqiao , Li Jingbo
Published: June 2012

Based on the first-principles calculations, we investigate the magnetic and electronic properties of α-graphyne nanoribbons (NRs). We show that all the armchair α-graphyne NRs are nonmagnetic semiconductors with band gaps as a function of ribbon widths. The zigzag α-graphyne NRs are found to have magnetic semiconducting ground state with ferromagnetic ordering at each edge and opposite spin orientation between the two edges. Under the application of transverse electric field, we further predict the existence of half-metallicity in the zigzag NRs which strongly depends on the width of the ribbon.
Modal approach for tailoring the absorption in a photonic crystal membrane
Authors: Peretti Romain , Gomard Guillaume , Seassal Christian , Letartre Xavier , Drouard Emmanuel
Published: June 2012

In this paper, we propose a method for tailoring the absorption in a photonic crystal membrane. For that purpose, we first applied time domain coupled mode theory to such a subwavelength membrane and demonstrated that 100% resonant absorption can be reached even for a symmetric membrane, if degenerate modes are involved. Design rules were then derived from this model in order to tune the absorption. Subsequently, finite difference time domain simulations were used as a proof of concept and carried out on a low absorbing material (extinction coefficient = 10−2) with a high refractive index corresponding to the optical indices of amorphous silicon at around 720 nm. In doing so, 85% resonant absorption was obtained, which is significantly higher than the commonly reported 50% maximum value. Those results were finally analyzed and confronted to theory so as to extend our method to other materials, configurations and applications.
Hot electron extraction from CdTe quantum dots via beta carotene molecular energy levels
Authors: Pazhanivel T. , Nataraj D. , Devarajan V. P. , Senthil K. , Seol M. , Yong K.
Published: June 2012

We report our findings related to hot electron extraction from CdTe quantum dots, and we were able to do this by using beta carotene as an electron acceptor. Transient absorption spectra with two slow recovering negative bleaches at the absorption maximum of the molecule and quantum dot have indicated the slowing down of cooling process and the existence of hot carriers in this hybrid system.
High efficient external resonator Raman laser based on the monoclinic single crystal BaTeMo2O9
Authors: Gao Zeliang , Liu Shande , Zhang Shaojun , Zhang Weiguo , He Jingliang , Tao Xutang
Published: June 2012

In this paper spontaneous Raman spectra of monoclinic single crystals of BaTeMo2O9 (BTM) along the Z axis has been characterized, and a highly efficient stimulated Raman scattering laser operating at 1178 nm has been realized based on the BTM crystal. The Raman resonator possesses a threshold of 28 MW/cm2 at 1064 nm and a maximum output pulse energy of 19.2 mJ for the first-order Stokes with an optical-to-optical conversion efficiency of 48% and a slope efficiency of 61.2%. The largest optical-to-optical conversion efficiency can reach 50.4% at a pump energy of 28.8 mJ. Our experimental results demonstrate that BTM can be used as an excellent near and mid-infrared Raman laser material.
Preface to Special Topic: Selected Papers from the First International Workshop on “Diffusion of New Energy Technologies in China,” Shanghai, China, 2011
Authors: Ma Tieju
Published: June 2012

China’s fast growing economy is inducing various technology dynamics. Much attention and resources are being paid to new energy technologies in China. These eight selected papers are a collection of academic studies on modeling and policy analysis of the diffusion of new energy technologies in China. These studies were all presented during the First International Workshop on “Diffusion of New Energy Technologies in China,” held from 25–26 March 2011, in Shanghai, China.
A finite-temperature density functional study of electron self-trapping in 3He and 4He
Authors: Jin Dafei , Guo Wei
Published: June 2012

We introduce a compact finite-temperature density functional model to study electron self-trapping in both liquid and vapor 3He and 4He. This model can quantitatively reproduce the most essential thermodynamic properties of 3He and 4He along their liquid-vapor coexistence lines. The structures and energetics of self-trapped electron bubbles on the 1S ground state and 1P excited state are particularly investigated. Our results show that 1S and 1P bubbles exist in liquid at any temperature, whereas 1S bubbles exist in vapor only above 1.6 K in 3He and above 2.8 K in 4He, 1P bubbles exist in vapor only above 2.5 K in 3He and 4.0 K in 4He. An initially spherical 1P bubble is unstable against deformation towards a peanut shape. In liquid, a peanut-shaped 1P bubble is held from fission by surface tension until reaching the liquid-vapor critical point, whereas in vapor it always splits into two smaller bubbles. The existence of 1P bubbles in finite-temperature liquid helium and their fission instability in helium vapor reveal interesting physics in this system.
Anisotropic surface properties of micro/nanostructured a-C:H:F thin films with self-assembly applications
Authors: Freire V.-M. , Corbella C. , Bertran E. , Portal-Marco S. , Rubio-Roy M. , Andújar J.-L.
Published: June 2012

The singular properties of hydrogenated amorphous carbon (a-C:H) thin films deposited by pulsed DC plasma enhanced chemical vapor deposition (PECVD), such as hardness and wear resistance, make it suitable as protective coating with low surface energy for self-assembly applications. In this paper, we designed fluorine-containing a-C:H (a-C:H:F) nanostructured surfaces and we characterized them for self-assembly applications. Sub-micron patterns were generated on silicon through laser lithography while contact angle measurements, nanotribometer, atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to characterize the surface. a-C:H:F properties on lithographied surfaces such as hydrophobicity and friction were improved with the proper relative quantity of CH4 and CHF3 during deposition, resulting in ultrahydrophobic samples and low friction coefficients. Furthermore, these properties were enhanced along the direction of the lithography patterns (in-plane anisotropy). Finally, self-assembly properties were tested with silica nanoparticles, which were successfully assembled in linear arrays following the generated patterns. Among the main applications, these surfaces could be suitable as particle filter selector and cell colony substrate.
Weak ferromagnetism in La-doped BiFeO3 multiferroic thin films
Authors: Lazenka V. V. , Ravinski A. F. , Makoed I. I. , Vanacken J. , Zhang G. , Moshchalkov V. V.
Published: June 2012

Bi1−xLaxFeO3 thin films (x = 0.0, 0.3, 0.5) were grown on glass substrates by thermal physical vapor deposition. The monoclinically distorted crystal structure of the films was revealed by x-ray diffraction at room temperature. Field and temperature (up to 1000 K) dependences of magnetization were studied. Saturation of the room temperature magnetic hysteresis loop has been observed at magnetic field above 0.15 T, demonstrating the weak ferromagnetic nature of the thin films. Our magnetic force microscopy results show clearly the presence of magnetic domains in BFO thin films. These structural and magnetic properties suggest the absence of magnetic spiral spin structure in monoclinically distorted BFO-based thin films.
Direct evidence for stress-induced (001) anisotropy of rapid-annealed FePt thin films
Authors: Hsiao S. N. , Liu S. H. , Chen S. K. , Chin T. S. , Lee H. Y.
Published: June 2012

Roles of rapid thermal annealing (RTA) on the evolution of crystallographic anisotropy of single-layered FePt films have been characterized. We observed a huge biaxial tensile stress of 2.18 GPa induced with increasing heating rate from 0.5 to 40 K/s. The result is a transition of orientation from (111) to perfect (001) texture. The later then degrades at heating rates ≥80 K/s due to morphological variation. The advantages of RTA are to induce tensile stress by densification reaction within a very short time and to simultaneously impede thickness-dependent dynamic stress relaxation.
Effect of proton bombardment on InAs dots and wetting layer in laser structures
Authors: O’Driscoll I. , Blood P. , Smowton P. M. , Sobiesierski A. , Gwilliam R.
Published: June 2012

The effect of proton bombardment on carrier lifetime and photoluminescence of InAs quantum dots was measured. Optical absorption and transmission electron microscopy show the dots retain their integrity under bombardment. A decrease in ground state photoluminescence with increasing dose is not explained by the decrease in dot carrier lifetime alone, but also by bombardment-induced non-radiative recombination in the wetting layer, which reduces the dot electron population at fixed excitation. To exploit the relative radiation immunity of quantum dots, it is necessary to maximise the dot density and capture probability per dot to minimize the effect of wetting layer recombination.
Rotary transportation of magnetic nanoparticle chains on magnetic thin film array
Authors: Lee Chiun Peng , Tsai Hsin Yi , Lai Mei Feng
Published: June 2012

Rotary step like transportation of chains of magnetic nanoparticles along arrays of magnetic discs is demonstrated. The strong magnetic attraction between the magnetic discs and the chains prevents the particle chain from slipping and allows a more controllable and programmable chain transportation. Different types of rotary motions of the chains are observed, and the cell transportation via functionalized particle chains is also shown to demonstrate a potential application in bio transportation.
Core density gradient fluctuation measurement by differential interferometry in the helically symmetric experiment stellarator
Authors: Deng C. B. , Brower D. L.
Published: June 2012

The interferometer system on the Helically Symmetric eXperiment (HSX) stellarator uses an expanded beam and linear detector array to realize a multichord measurement. Unlike conventional interferometry which determines the plasma phase shift with respect to a reference, directly evaluating the phase between two adjacent chords can be employed to measure the change in plasma phase with impact parameter. This approach provides a measure of the equilibrium density gradient or the density gradient fluctuations and is referred to as differential interferometry. For central chords, measurements are spatially localized due to a geometrical weighting factor and can provide information on core density gradient fluctuations. The measurement requires finite coherence between fluctuations in the two spatially offset chords. This technique is applied on the HSX stellarator to measure both broadband turbulence and coherent modes. Spatial localization is exploited to isolate core turbulence changes associated with change in magnetic configuration or heating location.
Influence of ion source configuration and its operation parameters on the target sputtering and implantation process
Authors: Shalnov K. V. , Kukhta V. R. , Uemura K. , Ito Y.
Published: June 2012

In the work, investigation of the features and operation regimes of sputter enhanced ion-plasma source are presented. The source is based on the target sputtering with the dense plasma formed in the crossed electric and magnetic fields. It allows operation with noble or reactive gases at low pressure discharge regimes, and, the resulting ion beam is the mixture of ions from the working gas and sputtering target. Any conductive material, such as metals, alloys, or compounds, can be used as the sputtering target. Effectiveness of target sputtering process with the plasma was investigated dependently on the gun geometry, plasma parameters, and the target bias voltage. With the applied accelerating voltage from 0 to 20 kV, the source can be operated in regimes of thin film deposition, ion-beam mixing, and ion implantation. Multi-component ion beam implantation was applied to α-Fe, which leads to the surface hardness increasing from 2 GPa in the initial condition up to 3.5 GPa in case of combined N2-C implantation. Projected range of the implanted elements is up to 20 nm with the implantation energy 20 keV that was obtained with XPS depth profiling.
Spontaneous formation of double helical structure due to interfacial adhesion
Authors: Ji Xiang-Ying , Zhao Meng-Qiang , Wei Fei , Feng Xi-Qiao
Published: June 2012

Many quasi-one-dimensional micro/nanomaterials assume double or multi-stranded helical conformations, but the reasons are still unclear. On the basis of continuum mechanics analysis, we demonstrate that interfacial adhesion is a significant physical mechanism responsible for the formation of some double helices, especially at micro and nano scales and for soft materials. With the formation of a double helical structure by two nanowires, surface energy decreases while elastic strain energy increases. Their competition dictates the global morphology of adhered micro/nanowires or tubes. The theoretical model agrees well with relevant experiments.
Thickness dependent magnetic properties of (Ga,Mn)As ultrathin films
Authors: Proselkov O. , Sztenkiel D. , Stefanowicz W. , Aleszkiewicz M. , Sadowski J. , Dietl T. , Sawicki M.
Published: June 2012

We report on a monotonic reduction of Curie temperature in dilute ferromagnetic semiconductor (Ga,Mn)As upon a well controlled chemical-etching/oxidizing thinning from 15 nm down to complete removal of the ferromagnetic response. The effect already starts at the very beginning of the thinning process and is accompanied by the spin reorientation transition of the in-plane uniaxial anisotropy. We postulate that a negative gradient along the growth direction of self-compensating defects (Mn interstitial) and the presence of surface donor traps gives quantitative account on these effects within the p–d mean field Zener model with adequate modifications to take a nonuniform distribution of holes and Mn cations into account.
Photoluminescence of boron nitride nanosheets exfoliated by ball milling
Authors: Hua Li Lu , Chen Ying , Cheng Bing-Ming , Lin Meng-Yeh , Chou Sheng-Long , Peng Yu-Chain
Published: June 2012

The photoluminescence of boron nitride (BN) nanosheets exfoliated by ball milling method has been investigated. At room temperature, the nanosheets have strong deep ultraviolet (DUV) light emission at 224 nm and weak defect-related UV (∼300 nm) emission. The DUV peak profile slightly changes with the increase of milling time due to the increase of stacking faults caused by the shear force during milling. The decreased ∼300 nm emission after milling treatments has been attributed to the preferential orientation of the BN nanosheets on substrate and the strong polarization anisotropy of BN materials in luminescence.
Ultra-wideband coaxial hybrid coupler for load resilient ion cyclotron range of frequency heating at fusion plasmas
Authors: Kim H. J. , Bae Y. S. , Yang H. L. , Kwak J.-G. , Wang S. J. , Kim B. K. , Choi J. J.
Published: June 2012

We designed a high power and ultra-wideband two-section 3 dB coaxial hybrid coupler for load resilient ion cyclotron range of frequency heating by configuring asymmetric impedance matching using a three-dimensional simulation code, hfss. By adjusting the characteristic impedances of main and coupled lines of the hybrid coupler, we realized that the bandwidth of the proposed circuit is not only wider than that of a conventional three-section coupler, but also that the bandwidth is almost twice as wide compared to the conventional two-section hybrid coupler while maintaining the identical overall size.
Non-volatile ferroelectric gating of magnetotransport anisotropy in (Ga,Mn)(As,P)
Authors: Mikheev E. , Stolichnov I. , Huang Z. , Rushforth A. W. , Haigh J. A. , Campion R. P. , Edmonds K. W. , Gallagher B. L. , Setter N.
Published: June 2012

We demonstrate charge-mediated and non-volatile control of anisotropic magnetoresistance (AMR) in a dilute magnetic semiconductor (Ga,Mn)(As,P) with an integrated polymer ferroelectric gate. The persistent electric field associated with switchable polarization in the ferroelectric layer is shown to be capable of strongly modulating the AMR magnitude. Furthermore, ferroelectric gate switching has a profound impact on the nature of AMR, changing the symmetry of the effect and enhancing/suppressing the crystalline component of AMR. Thus, in addition to a rather weak modulation of the ferromagnetic Curie temperature (4-5 K) reported previously, the ferroelectric gate can induce a strong deterministic switching of the magnetotransport anisotropy.
Dielectric barrier discharge induced boundary layer suction
Authors: Im S. , Cappelli M. A.
Published: June 2012

Boundary layer downdraft suction and through-surface fluid removal is demonstrated with a streamwise oriented dielectric barrier discharges fabricated into a flat plate immersed in a 3.8 m/s freestream flow (Re = 72000). The velocity field is obtained by particle image velocimetry. Suction with through-surface fluid removal is found to thin the boundary layer and increases the velocity gradient in the vicinity of the wall by extracting slower fluid from the inner layer region. The effect of this suction on the boundary layer persists away from the center of the exposed electrode without inducing significant disturbances to the freestream flow.
ApoStream™, a new dielectrophoretic device for antibody independent isolation and recovery of viable cancer cells from blood
Authors: Gupta Vishal , Jafferji Insiya , Garza Miguel , Melnikova Vladislava O. , Hasegawa David K. , Pethig Ronald , Davis Darren W.
Published: June 2012

Isolation and enumeration of circulating tumor cells (CTCs) are used to monitor metastatic disease progression and guide cancer therapy. However, currently available technologies are limited to cells expressing specific cell surface markers, such as epithelial cell adhesion molecule (EpCAM) or have limited specificity because they are based on cell size alone. We developed a device, ApoStream™ that overcomes these limitations by exploiting differences in the biophysical characteristics between cancer cells and normal, healthy blood cells to capture CTCs using dielectrophoretic technology in a microfluidic flow chamber. Further, the system overcomes throughput limitations by operating in continuous mode for efficient isolation and enrichment of CTCs from blood. The performance of the device was optimized using a design of experiment approach for key operating parameters such as frequency, voltage and flow rates, and buffer formulations. Cell spiking studies were conducted using SKOV3 or MDA-MB-231 cell lines that have a high and low expression level of EpCAM, respectively, to demonstrate linearity and precision of recovery independent of EpCAM receptor levels. The average recovery of SKOV3 and MDA-MB-231 cancer cells spiked into approximately 12 × 106 peripheral blood mononuclear cells obtained from 7.5 ml normal human donor blood was 75.4% ± 3.1% (n = 12) and 71.2% ± 1.6% (n = 6), respectively. The intra-day and inter-day precision coefficients of variation of the device were both less than 3%. Linear regression analysis yielded a correlation coefficient (R2) of more than 0.99 for a spiking range of 4–2600 cells. The viability of MDA-MB-231 cancer cells captured with ApoStream was greater than 97.1% and there was no difference in cell growth up to 7 days in culture compared to controls. The ApoStream device demonstrated high precision and linearity of recovery of viable cancer cells independent of their EpCAM expression level. Isolation and enrichment of viable cancer cells from ApoStream enables molecular characterization of CTCs from a wide range of cancer types.
Superimposed coherent terahertz wave radiation from mono-energetically bunched multi-beam
Authors: Shin Young-Min
Published: June 2012

Intense coherent radiation is obtained from multiple electron beams monochromatically bunched over the wide higher-order-mode (HOM) spectral band in the THz regime. The overmoded waveguide corrugated by dielectric-implanted staggered gratings superimposes evanescent waves emitted from the low energy electron beams. The dispersion and transmission simulations of the three-beam slow wave structure show that the first two fundamental modes (TE10 and TE20) are considerably suppressed (∼−50 dB) below the multi-beam resonating mode (TE30) at the THz regime (0.8–1.24 THz). The theoretical calculations and particle-in-cell simulations show that with significantly higher interaction impedance and power growth rate radiation of the TE30 mode is ∼23 dBm and ∼50 dBm stronger than the TE10 and TE20 modes around 1 THz, respectively. This highly selective HOM multi-beam interaction has potential applications for power THz sources and high intensity accelerators.
Dynamic characteristics of gas-water interfacial plasma under water
Authors: Zheng S. J. , Zhang Y. C. , Ke B. , Ding F. , Tang Z. L. , Yang K. , Zhu X. D.
Published: June 2012

Gas-water interfacial plasmas under water were generated in a compact space in a tube with a sandglass-like structure, where two metal wires were employed as electrodes with an applied 35 kHz ac power source. The dynamic behaviors of voltage/current were investigated for the powered electrode with/without water cover to understand the effect of the gas-water interface. It is found that the discharge exhibits periodic pulsed currents after breakdown as the powered electrode is covered with water, whereas the electrical current reveals a damped oscillation with time with a frequency about 106 Hz as the powered electrode is in a vapor bubble. By increasing water conductivity, a discharge current waveform transition from pulse to oscillation presents in the water covering case. These suggest that the gas-water interface has a significant influence on the discharge property.
Femtosecond laser induced breakdown for combustion diagnostics
Authors: Kotzagianni M. , Couris S.
Published: June 2012

The focused beam of a 100 fs, 800 nm laser is used to induce a spark in some laminar premixed air-methane flames operating with variable fuel content (equivalence ratio). The analysis of the light escaping from the plasma revealed that the Balmer hydrogen lines, Hα and Hβ, and some molecular origin emissions were the most prominent spectral features, while the CN (Β2Σ+-Χ2Σ+) band intensity was found to depend linearly with methane content, suggesting that femtosecond laser induced breakdown spectroscopy can be a useful tool for the in-situ determination and local mapping of fuel content in hydrocarbon-air combustible mixtures.
Temperature dependent conductivity of polycrystalline Cu2ZnSnS4 thin films
Authors: Kosyak V. , Karmarkar M. A. , Scarpulla M. A.
Published: June 2012

The temperature-dependent conductivity of Cu2ZnSnS4 (CZTS) thin films prepared by sulfurization of different sputtered ZnS/Cu/Sn stacks and also of the same stack annealed for different times was investigated from 30-300 K. Fitting of the through-thickness conductivity requires a model including Mott variable-range hopping (M-VRH), nearest-neighbor hopping (NNH), and thermionic emission over grain boundary (GB) barriers. The GB barrier height varies sensitively from 50–150 (±5) meV with annealing and especially with [Cu]/([Zn] + [Sn]) ratio but is independent of [Zn]/[Sn] ratio. These results are critical for understanding the behavior of solar cells based on polycrystalline CZTS absorber layers.
Communication: Vibrational spectroscopy of atmospherically relevant acid cluster anions: Bisulfate versus nitrate core structures
Authors: Yacovitch Tara I. , Heine Nadja , Brieger Claudia , Wende Torsten , Hock Christian , Neumark Daniel M. , Asmis Knut R.
Published: June 2012

Infrared multiple photon dissociation spectra for the smallest atmospherically relevant anions of sulfuric and nitric acid allow us to characterize structures and distinguish between clusters with a bisulfate or a nitrate core. We find that bisulfate is the main charge carrier for HSO4−·H2SO4·HNO3 but not for NO3−·H2SO4·HNO3. For the mixed dimer anion, we find evidence for the presence of two isomers: HSO4−·HNO3 and NO3−·H2SO4. Density functional calculations accompany the experimental results and provide support for these observations.
Fabrication of paper-based microfluidic device using printed circuit technology
Authors: Zhang An-liang , Zha Yan
Published: June 2012

This paper describes the use of a printed circuit technology to generate hydrophilic channels in a filter paper. Patterns of channels were designed using Protel soft, and printed on a blank paper. Then, the patterns were transferred to a sheet copper using a thermal transfer printer. The sheet copper with patterns was dipped into ferric chloride solution to etch the whole patterns of the sheet copper. At last, the etched sheet copper was coated with a film of paraffin and then a filter paper. An electric iron was used to heat the other side of the sheet copper. The melting paraffin penetrated full thickness of the filter paper and formed a hydrophobic “wall”. Colorimetric assays for the presence of protein and glucose were demonstrated using the paper-based device. The work is helpful to researchers to fabricate paper-based microfluidic devices for monitoring health and detecting disease.
Identification of water-soluble organic carbon in non-urban aerosols using ultrahigh-resolution FT-ICR mass spectrometry: organic anions
Authors: Mazzoleni Lynn R. , Saranjampour Parichehr , Dalbec Megan M. , Samburova Vera , Hallar A. Gannet , Zielinska Barbara , Lowenthal Douglas H. , Kohl Steve
Published: June 2012

Environmental contextAerosol water-soluble organic carbon is a complex mixture of thousands of organic compounds which may have a significant influence on the climate-relevant properties of atmospheric aerosols. Using ultrahigh resolution mass spectrometry, more than 4000 individual molecular formulas were identified in non-urban aerosol water-soluble organic carbon. A significant fraction of the assigned molecular formulas were matched to assigned molecular formulas of laboratory generated secondary organic aerosols. AbstractWater-soluble organic carbon (WSOC) is a complex mixture of thousands of organic compounds which may have significant influence on the climate-relevant properties of atmospheric aerosols. An improved understanding of the molecular composition of WSOC is needed to evaluate the effect of aerosol composition upon aerosol physical properties. In this work, ultrahigh-resolution Fourier transform–ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterise aerosol WSOC collected during the summer of 2010 at the Storm Peak Laboratory (3210 m ASL) near Steamboat Springs, CO. Approximately 4000 molecular formulas were assigned in the mass range of 100–800 Da after negative-ion electrospray ionisation and more than 50 % of them contained nitrogen or sulfur. The double bond equivalents (DBEs) of the molecular formulas were inversely proportional to the O : C ratio, despite a relatively constant H : C ratio of ~1.5. Despite the range of DBE values, the elemental ratios and the high number of oxygen atoms per formula indicate that a majority of the compounds are aliphatic to olefinic in nature. These trends indicate significant non-oxidative accretion reaction pathways for the formation of high molecular weight WSOC components. In addition, a significant number of molecular formulas assigned in this work matched those previously identified as secondary organic aerosol components of monoterpene and sesquiterpene ozonolysis.
Assessment of biogenic secondary organic aerosol in the Himalayas
Authors: Stone Elizabeth A. , Nguyen Tony T. , Pradhan Bidya Banmali , Man Dangol Pradeep
Published: June 2012

Environmental contextSecondary organic aerosols derived from biogenic gases are ubiquitous in the atmosphere. We found that biogenic secondary organic aerosol in Nepal accounted for 6 to 23 % of organic carbon. Primary and secondary biogenic sources combined accounted for approximately half of the observed organic aerosol, suggesting that additional aerosol sources or precursors are significant in this region of the Himalayas. AbstractBiogenic contributions to secondary organic aerosol (SOA) in the South-East Asian regional haze were assessed by measurement of isoprene, monoterpene and sesquiterpene photooxidation products in fine particles (PM2.5) at a mid-latitude site in the Himalayas. Organic species were measured in solvent extracts of filter samples using gas chromatography–mass spectrometry (GCMS) and chemical derivatisation; this analysis was used to quantify molecular markers for primary aerosol sources – including motor vehicles, biomass burning and detritus – and SOA tracers. Authentic standards of most SOA products were not commercially available at the time of this study, so surrogate standards were used for semiquantitation. Using an empirical approach to uncertainty estimation based on homologous series of atmospherically relevant model compounds, analytical uncertainties ranged from 32 % for SOA tracers with structurally similar surrogates to more than 100 % for tracers with a poorly matched surrogate. Biogenic SOA contributions to PM2.5 organic carbon content in the 2005 monsoon and post-monsoon season ranged from 2–19 % for isoprene, 1–5 % for monoterpenes and 1–4 % for sesquiterpenes. High concentrations of isoprene derivatives in aerosol, particularly in the late summer months, point to biogenic SOA as a significant source of organic carbon in the Himalayan region.
There Are No Universal Rules for Induction
Authors: Norton John D.
Published: June 2012

In a material theory of induction, inductive inferences are warranted by facts that prevail locally. This approach, it is urged, is preferable to formal theories of induction in which the good inductive inferences are delineated as those conforming to universal schemas. An inductive inference problem concerning indeterministic, nonprobabilistic systems in physics is posed, and it is argued that Bayesians cannot responsibly analyze it, thereby demonstrating that the probability calculus is not the universal logic of induction.
What's Wrong with the New Biological Essentialism
Authors: Ereshefsky Marc
Published: June 2012

The received view in the philosophy of biology is that biological taxa (species and higher taxa) do not have essences. Recently, some philosophers (Boyd, Devitt, Griffiths, LaPorte, Okasha, and Wilson) have suggested new forms of biological essentialism. They argue that according to these new forms of essentialism, biological taxa do have essences. This article critically evaluates the new biological essentialism. This article's thesis is that the costs of adopting the new biological essentialism are many, yet the benefits are none, so there is no compelling reason to resurrect essentialism concerning biological taxa.
Computation, San Diego Style
Authors: Shagrir Oron
Published: June 2012

What does it mean to say that a physical system computes or, specifically, to say that the nervous system computes? One answer, endorsed here, is that computing is a sort of modeling. I trace this line of answer in the conceptual and philosophical work conducted over the last 3 decades by researchers associated with the University of California, San Diego (UCSD). The linkage between their work and the modeling notion is no coincidence: the modeling notion aims to account for the computational approach in neuroscience, and UCSD has been home to central studies in neurophilosophy, connectionism, and computational neuroscience.
I'd Love to Be a Naturalist—if Only I Knew What Naturalism Was
Authors: Sklar Lawrence
Published: June 2012

Naturalists tell us to rely on what science tells about the world and to eschew aprioristic philosophy. But foundational physics relies internally on modes of thinking that can only be called philosophical, and philosophical arguments rely upon what can only be called scientific inference. So what, then, could the naturalistic thesis really amount to?
Inflammasomes and viruses: cellular defence versus viral offence
Authors: Gram Anna M. , Frenkel Joost , Ressing Maaike E.
Published: June 2012

Pro-inflammatory cytokines are important mediators in immune responses against invading pathogens, including viruses. Precursors of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 are processed by caspase-1. Caspase-1 is activated through autocleavage, but how this is regulated remained elusive for a long time. In 2002, an intracellular multimeric complex was discovered that facilitated caspase-1 cleavage and was termed ‘inflammasome’. To date, different inflammasomes have been described, which recognize a variety of ligands and pathogens. In this review, we discuss the role of inflammasomes in sensing viral infection as well as the evasion strategies that viruses developed to circumvent inflammasome-dependent effects.
A single nucleotide mutation in NS2A of Japanese encephalitis-live vaccine virus (SA14-14-2) ablates NS1’ formation and contributes to attenuation
Authors: Ye Qing , Li Xiao-Feng , Zhao Hui , Li Shi-Hua , Deng Yong-Qiang , Cao Rui-Yuan , Song Ke-Yu , Wang Hong-Jiang , Hua Rong-Hong , Yu Yong-Xin , Zhou Xi , Qin E-De , Qin Cheng-Feng
Published: June 2012

Japanese encephalitis (JE) remains the leading cause of viral encephalitis in the Asia-Pacific region, and the live vaccine SA14-14-2 is currently recommended by WHO and widely used in Asian countries with a good safety and efficacy profile. In this study, we demonstrated that SA14-14-2 failed to produce NS1’, the larger NS1-related protein, compared with its parental strain SA14 in various cells. Sequence analysis and secondary structure prediction identified a single silent mutation G66A in the NS2A-coding region of SA14-14-2 destabilized the conserved pseudoknot structure, which was associated with a −1 ribosomal frame shift event. Using reverse genetic technology and animal study, we provided solid evidence that this single silent mutation G66A in the NS2A gene abolished the production of NS1’ in vitro and reduced neurovirulence and neuroinvasiveness in mice. These findings provide critical information in understanding the molecular mechanism of JE vaccine attenuation and is critical for JE vaccine quality control.
On the charge transfer between conventional cations: the structures of ternary oxides and chalcogenides of alkali metals
Authors: Vegas Angel
Published: June 2012

The structures of ternary oxides and chalcogenides of alkali metals are dissected in light of the extended Zintl–Klemm concept. This model, which has been successfully extended to other compounds different to the Zintl phases, assumes that crystal structures can be better understood if the cation substructures are contemplated as Zintl polyanions. This implies the occurrence of charge transfer between cations, even if they are of the same kind. In this article, the charge transfer between cations is even more illustrative because the two alkali atoms have different electronegativity, so that the less electropositive alkali metal and the O/S atom always form skeletons characteristic of the group 14 elements. Thus, partial structures of the zincblende-, wurtzite-, PbO- and SrAl2-type are found in the oxides/sulfides. In this work, such an interpretation of the structures remains at a topological level. The analysis also shows that this interpretation is complementary to the model developed by Andersson and Hyde which contemplates the structures as the intergrowth of structural slabs of more simple compounds.
Rhynchosporium commune: a persistent threat to barley cultivation
Authors: Avrova Anna , Knogge Wolfgang
Published: June 2012

Rhynchosporium commune is a haploid fungus causing scald or leaf blotch on barley, other Hordeum spp. and Bromus diandrus.

Taxonomy

Rhynchosporium commune is an anamorphic Ascomycete closely related to the teleomorph Helotiales genera Oculimacula and Pyrenopeziza.

Disease symptoms

Rhynchosporium commune causes scald‐like lesions on leaves, leaf sheaths and ears. Early symptoms are generally pale grey oval lesions. With time, the lesions acquire a dark brown margin with the centre of the lesion remaining pale green or pale brown. Lesions often merge to form large areas around which leaf yellowing is common. Infection frequently occurs in the leaf axil, which can lead to chlorosis and eventual death of the leaf.

Life cycle

Rhynchosporium commune is seed borne, but the importance of this phase of the disease is not fully understood. Debris from previous crops and volunteers, infected from the stubble from previous crops, are considered to be the most important sources of the disease. Autumn‐sown crops can become infected very soon after sowing. Secondary spread of disease occurs mainly through splash dispersal of conidia from infected leaves. Rainfall at the stem extension growth stage is the major environmental factor in epidemic development.

Detection and quantification

Rhynchosporium commune produces unique beak‐shaped, one‐septate spores both on leaves and in culture. The development of a specific polymerase chain reaction (PCR) and, more recently, quantitative PCR (qPCR) has allowed the identification of asymptomatic infection in seeds and during the growing season.

Disease control

The main measure for the control of R. commune is the use of fungicides with different modes of action, in combination with the use of resistant cultivars. However, this is constantly under review because of the ability of the pathogen to adapt to host plant resistance and to develop fungicide resistance.
On measures of association among genetic variables
Authors: Gianola Daniel , Manfredi Eduardo , Simianer Henner
Published: June 2012

Systems involving many variables are important in population and quantitative genetics, for example, in multi‐trait prediction of breeding values and in exploration of multi‐locus associations. We studied departures of the joint distribution of sets of genetic variables from independence. New measures of association based on notions of statistical distance between distributions are presented. These are more general than correlations, which are pairwise measures, and lack a clear interpretation beyond the bivariate normal distribution. Our measures are based on logarithmic (Kullback‐Leibler) and on relative ‘distances’ between distributions. Indexes of association are developed and illustrated for quantitative genetics settings in which the joint distribution of the variables is either multivariate normal or multivariate‐t, and we show how the indexes can be used to study linkage disequilibrium in a two‐locus system with multiple alleles and present applications to systems of correlated beta distributions. Two multivariate beta and multivariate beta‐binomial processes are examined, and new distributions are introduced: the GMS‐Sarmanov multivariate beta and its beta‐binomial counterpart.
Familial short stature and intrauterine growth retardation associated with a novel mutation in the IGF‐I receptor (IGF1R) gene
Authors: Labarta José I. , Barrio Eva , Audí Laura , Fernández‐Cancio Mónica , Andaluz Pilar , de Arriba Antonio , Puga Beatriz , Calvo María T. , Mayayo Esteban , Carrascosa Antonio , Ferrández‐Longás Angel
Published: June 2012

Context

IGF‐I is essential for normal human growth and mediates its effects through the IGF1R. IGF1R mutations have been associated with varying degrees of intrauterine and postnatal growth retardation.

Objective

To identify IGF1R gene mutations in a short‐statured family with intrauterine growth retardation and microcephaly.

Methods

Direct DNA sequencing was used to identify IGF1R mutations. Multiplex ligation‐dependent probe amplification analyses were performed for deletions and duplications of all IGF1R exons. Functional studies were conducted to assess mutation pathogenicity.

Results

A novel heterozygous IGF1R missense mutation in exon 7 (c.A1549T, p.Y487F) was identified in a short‐statured girl with severe prenatal growth retardation and microcephaly. The same mutation was also identified in her mother, who presented prenatal and postnatal growth failure, and her short‐statured maternal grandmother, both of whom exhibited microcephaly. The index case showed a partial response to rhGH. Functional studies performed in dermal fibroblasts from the index case and her mother showed normal IGF‐I binding; however, IGF‐I activation of intracellular signalling measured as AKT and extracellular signal–regulated kinase phosphorylation was markedly reduced, with patients' values being lower than those of her mother. IGF‐I stimulation of DNA synthesis was significantly reduced compared with controls.

Conclusion

Our results show a novel missense mutation in the IGF1R gene (c.A1549T, p.Y487F) associated with prenatal and postnatal growth failure and microcephaly in the context of familial short stature. The functional studies are in line with the inactivation of one copy of the IGF1R gene with variable expression within the same family.