bluuebunny/crossref_metadata_2025 huggingface dataset:
Millennial variability and long‐term changes of the diatom production in the eastern equatorial Pacific during the last glacial cycle
Authors: Romero Oscar E. , Leduc Guillaume , Vidal Laurence , Fischer Gerhard
Published: May 2011

The modern eastern equatorial Pacific (EEP) is a major natural source for atmospheric carbon dioxide and is thought to be connected to high‐latitude ocean dynamics by oceanic teleconnections on glacial‐interglacial timescales. A wealth of sedimentary records aiming at reconstructing last Quaternary changes in primary productivity and nutrient utilization have been devoted to understanding those linkages between the EEP and other distant oceanic areas. Most of these records are, however, clustered in the pelagic EEP cold tongue, with comparatively little attention devoted to coastal areas. Here we present downcore measurements of the composition and concentration of the diatom assemblage together with opal (biogenic silica) concentration at site MD02‐2529 recovered in the coastal Panama Basin. Piston core MD02‐2529, collected in an area affected by a multitude of processes, provides evidence for strong variations in diatom production at the millennial timescale during the last glacial cycle. The maxima in total diatom concentration occurred during the early marine isotopic stage (MIS) 4 as well as during the MIS 4/3 transition and MIS 3. Rapid changes in diatom concentrations during the MIS 3 mimics Bond cycles as independently recorded by the sea surface salinity estimation derived from planktonic foraminifera from the same core. Such patterns indicate a clear linkage between diatom production in the coastal EEP and rapid climate changes in the high‐latitude North Atlantic. In parallel, the long‐term succession of the diatom community from coastal diatoms, predominantly thriving during MIS 5 and 4, toward pelagic diatoms, dominant during MIS 3 and 2, points to a long‐term change in the surface hydrology. During Heinrich events, diatoms strongly reduced their production, probably because of enhanced stratification in the upper water column. After the last glacial maximum, diatom production and valve preservation strongly decreased in response to the advection of nutrient‐depleted (H2SiO4), warmer water masses. Our high‐resolution record highlights how regional climatic processes can modulate rapid changes in siliceous primary production as triggered by wind‐induced local upwelling, indicating that millennial climatic variability can overtake other prominent hydrological processes such as those related to silicic acid leakage.
Modeling the long‐term and transient evolution of biogeochemical and isotopic signatures in coal tar–contaminated aquifers
Authors: D'Affonseca Fernando Mazo , Prommer Henning , Finkel Michael , Blum Philipp , Grathwohl Peter
Published: May 2011

Reactive transport modeling is a critical element in assessing the potential of natural attenuation of groundwater pollutants. In the present study, we developed a comprehensive quantitative model that incorporates the key processes affecting the long‐term fate of complex organic compound mixtures released from coal tar–type dense nonaqueous phase liquid sources. The model framework addresses the simulation of the long‐term dynamics of source zone depletion, the fate of the released compounds during reactive transport in the groundwater, the evolution of the aquifer's biogeochemical response, in particular its redox conditions, and the redox‐dependent carbon isotope fractionation of selected organic compounds. The modeling framework was applied for the interpretation of observed biogeochemical and isotopic data from a well‐characterized coal tar–contaminated site in northern Germany. The simulations highlight the diversity of fates of the individual compounds, which result from their widely varying physicochemical characteristics, and also how complex interactions develop over the lifetime of the contamination. The highly transient release of contaminants from the coal tar as pool and as heterogeneously distributed blobs in the source zone triggers continuously changing biogeochemical conditions and isotope signatures. The modeling results illustrate how difficult and uncertain the assessment of contaminant fate can be if the collected data cover only a small time window relative to the transport time scale. This emphasizes the need for a holistic understanding of the governing processes that control the effectiveness of monitored natural attenuation before it is implemented as a passive remediation strategy at nonaqueous phase liquid–contaminated sites.
Measuring and modeling the flux of fecal bacteria across the sediment‐water interface in a turbulent stream
Authors: Grant Stanley B. , Litton‐Mueller Rachel M. , Ahn Jong H.
Published: May 2011

Sediments are a pervasive source of fecal indicator bacteria (FIB) in rivers, lakes, estuaries, and oceans and may constitute a long‐term reservoir of human disease. Previous attempts to quantify the flux of FIB across the sediment‐water interface (SWI) are limited to extreme flow events, for which the primary mechanism of bacterial release is disruption and/or erosion of the sediment substrate. Here we report measurements of FIB flux across the SWI in a turbulent stream that is not undergoing significant erosion. The stream is formed by the steady discharge of bacteria‐free disinfected and highly treated wastewater effluent to an earthen channel harboring high concentrations of FIB in the sediment from in situ growth. The flux j″ of FIB across the SWI, estimated from mass balance on FIB measurements in the water column, scales linearly with the concentration of bacteria in sediment pore fluids Cpore over a 3 decade change in both variables: The magnitude of the observed mass transfer velocity ( m s−1) is significantly larger than values predicted for either the diffusion of bacteria across a concentration boundary layer ( m s−1) or sweep and eject fluid motions at the SWI ( m s−1) but is similar to the flux of water between the stream and its hyporheic zone estimated from dye injection experiments. These results support the hypothesis that hyporheic exchange controls the trafficking of bacteria, and perhaps other types of particulate organic matter, across the SWI in turbulent streams.
West African Monsoon influence on the summer Euro‐Atlantic circulation
Authors: Gaetani Marco , Pohl Benjamin , Douville Hervé , Fontaine Bernard
Published: May 2011

The West African Monsoon (WAM) influence on the interannual variability of the summer atmospheric circulation over North Atlantic and Europe is investigated over the period 1971–2000. A set of sensitivity experiments performed through the Arpege‐Climat Atmospheric General Circulation Model is analyzed, using the so‐called “grid‐point nudging” technique, where the simulated atmospheric fields in the WAM region are relaxed towards the ERA40 reanalysis. Observations confirm that a sizable part of the Euro‐Atlantic circulation variability is related to the WAM, with anomalies of reinforced convection in the Sudan‐Sahel region associated with positive North Atlantic Oscillation (NAO) phases and subsidence over eastern Mediterranean. The nudged simulations highlights the role of the WAM in driving the mid‐latitude circulation. A strong monsoon is related to high‐pressure anomalies over the Azores and positive NAO phases.
Identification of a novel acetate-utilizing bacterium belonging to Synergistes group 4 in anaerobic digester sludge
Authors: Ito Tsukasa , Yoshiguchi Kazumi , Ariesyady Herto Dwi , Okabe Satoshi
Published: May 2011

Major acetate-utilizing bacterial and archaeal populations in methanogenic anaerobic digester sludge were identified and quantified by radioisotope- and stable-isotope-based functional analyses, microautoradiography-fluorescence in situ hybridization (MAR-FISH) and stable-isotope probing of 16S rRNA (RNA-SIP) that can directly link 16S rRNA phylogeny with in situ metabolic function. First, MAR-FISH with 14C-acetate indicated the significant utilization of acetate by only two major groups, unidentified bacterial cells and Methanosaeta-like filamentous archaeal cells, in the digester sludge. To identify the acetate-utilizing unidentified bacteria, RNA-SIP was conducted with 13C6-glucose and 13C3-propionate as sole carbon source, which were followed by phylogenetic analysis of 16S rRNA. We found that bacteria belonging to Synergistes group 4 were commonly detected in both 16S rRNA clone libraries derived from the sludge incubated with 13C-glucose and 13C-propionate. To confirm that this bacterial group can utilize acetate, specific FISH probe targeting for Synergistes group 4 was newly designed and applied to the sludge incubated with 14C-acetate for MAR-FISH. The MAR-FISH result showed that bacteria belonging to Synergistes group 4 significantly took up acetate and their active population size was comparable to that of Methanosaeta in this sludge. In addition, as bacteria belonging to Synergistes group 4 had high K  m for acetate and maximum utilization rate, they are more competitive for acetate over Methanosaeta at high acetate concentrations (2.5–10 mm). To our knowledge, it is the first time to report the acetate-utilizing activity of uncultured bacteria belonging to Synergistes group 4 and its competitive significance to acetoclastic methanogen, Methanosaeta.
The Influence of Body Composition, Fat Distribution, and Sustained Weight Loss on Left Ventricular Mass and Geometry in Obesity
Authors: Kardassis Dimitris , Bech‐Hanssen Odd , Schönander Marie , Sjöström Lars , Karason Kristjan
Published: May 2011

Alterations in left ventricular mass and geometry vary along with the degree of obesity, but mechanisms underlying such covariation are not clear. In a case–control study, we examined how body composition and fat distribution relate to left ventricular structure and examine how sustained weight loss affects left ventricular mass and geometry. At the 10‐year follow‐up of the Swedish obese subjects (SOS) study cohort, we identified 44 patients with sustained weight losses after bariatric surgery (surgery group) and 44 matched obese control patients who remained weight stable (obese group). We also recruited 44 matched normal weight subjects (lean group). Dual‐energy X‐ray absorptiometry, computed tomography, and echocardiography were performed to evaluate body composition, fat distribution, and left ventricular structure. BMI was 42.5 kg/m2, 31.5 kg/m2, and 24.4 kg/m2 for the obese, surgery, and lean groups, respectively. Corresponding values for left ventricular mass were 201.4 g, 157.7 g, and 133.9 g (P < 0.001). In multivariate analyses, left ventricular diastolic dimension was predicted by lean body mass (β = 0.03, P < 0.001); left ventricular wall thickness by visceral adipose tissue (β = 0.11, P < 0.001) and systolic blood pressure (β = 0.02, P = 0.019); left ventricular mass by lean body mass (β = 1.23, P < 0.001), total body fat (β = 1.15, P < 0.001) and systolic blood pressure (β = 2.72, P = 0.047); and relative wall thickness by visceral adipose tissue (β = 0.02, P < 0.001). Left ventricular adjustment to body size is dependent on body composition and fat distribution, regardless of blood pressure levels. Obesity is associated with concentric left ventricular remodeling and sustained 10‐year weight loss results in lower cavity size, wall thickness and mass.
Urinary C‐peptide Is Not an Accurate Bioindicator of Energy Balance in Humans
Authors: Bergouignan Audrey , Habold Caroline , Rudwill Floriane , Gauquelin‐Koch Guillemette , Normand Sylvie , Simon Chantal , Blanc Stéphane
Published: May 2011

The apprehension of the factors that affect long term regulation of energy balance is indispensable to understand the rise in obesity prevalence as well as to delineate levers to prevent it. Accurate measurements of energy balance are however challenging during free‐living conditions. Recent studies proposed urinary C‐peptide, a metabolic byproduct of insulin synthesis, as reliable noninvasive assessment of energy balance. These studies were in fact essentially based on correlations between urinary C‐peptide and energy intake and only focused on nonhuman primates. During a bed‐rest study conducted in 16 healthy women in a controlled environment, we tested the existence of a relationship between 24 h‐urinary C‐peptide and energy balance in humans. Daily energy intake and body mass, body composition (dual‐energy X‐ray absorptiometry (DXA)) and total energy expenditure (doubly labeled water (DLW) method) was measured and energy balance was calculated as the difference between energy intake and expenditure. Urinary C‐peptide was positively correlated with bed‐rest‐induced changes in fat mass (r2 = 0.285; P = 0.03) and energy balance assessed at the end of the bed‐rest (r2 = 0.302; P = 0.027). However, in this tightly controlled environment, urinary C‐peptide only accounted for 30% of variations in energy balance. No relationship was noted between urinary C‐peptide and body or fat mass both at baseline and at the end of the bed‐rest. These results indicate that urinary C‐peptide cannot be used as an accurate biomarker of energy balance in the general human population in free‐living conditions.
Age‐Related Decrease in Cold‐Activated Brown Adipose Tissue and Accumulation of Body Fat in Healthy Humans
Authors: Yoneshiro Takeshi , Aita Sayuri , Matsushita Mami , Okamatsu‐Ogura Yuko , Kameya Toshimitsu , Kawai Yuko , Miyagawa Masao , Tsujisaki Masayuki , Saito Masayuki
Published: May 2011

Brown adipose tissue (BAT) can be identified by 18F‐fluorodeoxyglucose (FDG)‐positron emission tomography (PET) combined with X‐ray computed tomography (CT) in adult humans. The objective of this study was to clarify the relationship between BAT and adiposity in healthy adult humans, particularly to test the idea that decreased BAT activity may be associated with body fat accumulation with age. One hundred and sixty‐two healthy volunteers aged 20–73 years (103 males and 59 females) underwent FDG‐PET/CT after 2‐h cold exposure at 19 °C with light clothing. Cold‐activated BAT was detected in 41% of the subjects (BAT‐positive). Compared with the BAT‐negative group, the BAT‐positive group was younger (P < 0.01) and showed a lower BMI (P < 0.01), body fat content (P < 0.01), and abdominal fat (P < 0.01). The incidence of cold‐activated BAT decreased with age (P < 0.01), being more than 50% in the twenties, but less than 10% in the fifties and sixties. The adiposity‐related parameters showed some sex differences, but increased with age in the BAT‐negative group (P < 0.01), while they remained unchanged from the twenties to forties in the BAT‐positive group, in both sexes. These results suggest that decreased BAT activity may be associated with accumulation of body fat with age.
Free-boundary toroidal Alfvén eigenmodes
Authors: Chen Eugene Y. , Berk H. L. , Breizman B. , Zheng L. J.
Published: May 2011

A numerical study is presented for the n = 1 free-boundary toroidal Alfvén eigenmodes (TAE) in tokamaks, which shows that there is considerable sensitivity of n = 1 modes to the position of the conducting wall. An additional branch of the TAE is shown to emerge from the upper continuum as the ratio of conducting wall radius to plasma radius increases. Such phenomena arise in plasma equilibria with both circular and shaped cross sections, where the shaped profile studied here is similar to that found in Alcator C-Mod.
Cauchy problem for a damped generalized IMBq equation
Authors: Chen Guowang , Rui Weifang , Chen Xiangying
Published: May 2011

In this paper, we prove that the Cauchy problem for the following damped generalized IMBq equation, \documentclass[12pt]{minimal}\begin{document}$u_{tt}-u_\textit{\scriptsize xx}-u_\textit{\scriptsize xxtt}+\nu _2 u_\textit{\scriptsize xxt}=f(u)_\textit{\scriptsize xx}, x\in \mathbb {R}, t>0,$\end{document}utt−uxx−uxxtt+ν2uxxt=f(u)xx,x∈R,t>0, admits a unique global generalized solution in \documentclass[12pt]{minimal}\begin{document}$C^3([0,\infty );W^{m,p}(\mathbb {R})\cap L^\infty (\mathbb {R})\cap L^2 (\mathbb {R})) (1\break \leq p \leq \infty,m\ge 0)$\end{document}C3([0,∞);Wm,p(R)∩L∞(R)∩L2(R))(1≤p≤∞,m≥0) and a unique global classical solution in \documentclass[12pt]{minimal}\begin{document}$C^3([0,\infty );W^{m,p}(\mathbb {R})\cap L^\infty (\mathbb {R}) \cap L^2(\mathbb {R}) ) (m>2+\frac{1}{p})$\end{document}C3([0,∞);Wm,p(R)∩L∞(R)∩L2(R))(m>2+1p). Moreover, the blow up of the solution for the Cauchy problem of damped generalized IMBq equation is studied. We also prove that the Cauchy problem of the above-mentioned equation has a unique global generalized solution in \documentclass[12pt]{minimal}\begin{document}$C^2([0,\infty );H^s(\mathbb {R}) )(s > \frac12)$\end{document}C2([0,∞);Hs(R))(s>12) and a unique global classical solution in \documentclass[12pt]{minimal}\begin{document}$C^2([0,\infty );H^s(\mathbb {R}))(s>\frac{5}{2})$\end{document}C2([0,∞);Hs(R))(s>52), and discuss the blow up of the solution.
Doping efficiency, optical and electrical properties of nitrogen-doped ZnO films
Authors: Liu W. W. , Yao B. , Zhang Z. Z. , Li Y. F. , Li B. H. , Shan C. X. , Zhang J. Y. , Shen D. Z. , Fan X. W.
Published: May 2011

Doping efficiency and optical and electrical properties of the N-doped ZnO films grown on c-sapphire were investigated. An anomalous Raman mode at 275 cm−1 was observed in the films grown at high Zn temperature, which implied that the films have a large number of defects induced by high N concentration. The intensity ratio of the donor-acceptor pair (DAP)/donor-bound exciton (DX) increases with increasing Zn temperature; this was attributed to the increase of N concentration. The films exhibit a conversion from n-type to p-type conductivity with increasing Zn temperature, and reproducible p-type conductivity was obtained at the Zn temperature of 255 °C. This study offers a simple and effective route to enhance the N solubility in ZnO films and confirms that the anomalous Raman mode at 275 cm−1 was related to substitution of N for O site (NO) and not related to substitution of N2 for O site (N2)O.
Molecular dynamic simulation for laser–cluster interaction
Authors: Holkundkar Amol R. , Mishra Gaurav , Gupta N. K.
Published: May 2011

A three dimensional relativistic molecular dynamic model for studying the laser interaction with atomic clusters is presented. The model is used to simulate the interaction dynamics of deuterium, argon, and xenon clusters when irradiated by the short and high intensity laser pulses. The interaction of 82 Å argon cluster by 100 fs, 806 nm laser pulse with the peak intensity of 8 × 1015 W/cm2 is studied and compared with the experimental results. The maximum ion energy in this case is found to be about 200 keV. Ion energies along and perpendicular to laser polarization direction is calculated and asymmetry along laser polarization direction is detected which is further explained on the basis of charge flipping model. The effect of cluster density on the energetics of the laser–cluster interaction is also being studied, which provides a qualitative understanding of the presence of optimum cluster size for maximum ion energies.
Cross-plane thermal diffusivity measurement of an operating vertical cavity surface emitting laser using thermoreflectance
Authors: Farzaneh M. , Harris Alphonse F. , Lebovitz Adam
Published: May 2011

Cross-plane thermal diffusivity of a GaAs/AlGaAs-based vertical cavity surface emitting laser (VCSEL) is measured under operating conditions and active heat sinking using a thermoreflectance technique. Perpendicular thermal diffusivity is determined from the measurements of phase difference between the heating source and the temperature as a function of temperature modulation frequency. The value of (1.22 ± 0.23) × 10-6 m2/s is obtained for thermal diffusivity, which is of the same order as previous values obtained on unbiased VCSEL structures. This is 10−14 times smaller than the corresponding bulk value. The reduction is attributed to the increase in phonon-boundary scattering in the multilayer structure of the VCSEL.
Inconsistencies of the complete sets of electromechanical constants of relaxor-ferroelectric single crystals
Authors: Yu. Topolov V. , Bowen C. R.
Published: May 2011

Complete sets of elastic, dielectric, and piezoelectric constants of relaxor-ferroelectric single crystals of (1 – x)Pb(A1/3Nb2/3)·O3 − xPbTiO3 (A = Mg or Zn) and Pb(In1/2Nb1/2)O3 − Pb(Mg1/3Nb2/3)·O3 − PbTiO3 are analyzed to demonstrate violations of the interrelations between particular groups of electromechanical constants and the resulting influence of the inconsistent properties on the thermodynamic stability and electromechanical coupling in single crystals. The possibilities of refinement and correction of inconsistent constants are discussed and presented for specific examples of relaxor-ferroelectric single crystals.
A modular designed ultra-high-vacuum spin-polarized scanning tunneling microscope with controllable magnetic fields for investigating epitaxial thin films
Authors: Wang Kangkang , Lin Wenzhi , Chinchore Abhijit V. , Liu Yinghao , Smith Arthur R.
Published: May 2011

A room-temperature ultra-high-vacuum scanning tunneling microscope for in situ scanning freshly grown epitaxial films has been developed. The core unit of the microscope, which consists of critical components including scanner and approach motors, is modular designed. This enables easy adaptation of the same microscope units to new growth systems with different sample-transfer geometries. Furthermore the core unit is designed to be fully compatible with cryogenic temperatures and high magnetic field operations. A double-stage spring suspension system with eddy current damping has been implemented to achieve ⩽5 pm z stability in a noisy environment and in the presence of an interconnected growth chamber. Both tips and samples can be quickly exchanged in situ; also a tunable external magnetic field can be introduced using a transferable permanent magnet shuttle. This allows spin-polarized tunneling with magnetically coated tips. The performance of this microscope is demonstrated by atomic-resolution imaging of surface reconstructions on wide band-gap GaN surfaces and spin-resolved experiments on antiferromagnetic Mn3N2(010) surfaces.
Charge transport in dielectrics via tunneling between traps
Authors: Nasyrov K. A. , Gritsenko V. A.
Published: May 2011

A theory for charge transport in dielectrics via tunneling between traps was developed. Unlike in the Frenkel model, in the present theory the traps are characterized with the thermal and optical ionization energies, and ionization proceeds by the multi-phonon mechanism. The theory predicts the tunneling between such traps to be a thermally stimulated process whose activation energy equals half to the difference between the optical and thermal ionization energies. The theory provides an adequate description to the experimental current-voltage characteristics of silicon-rich silicon nitride films. Such films have a high density of traps originating from the excess silicon present in the material, with charge transport proceeding as a charge carriers tunnel between closely spaced traps.
Spin-torque oscillator linewidth narrowing under current modulation
Authors: Pogoryelov Ye. , Muduli P. K. , Bonetti S. , Mancoff Fred , Åkerman Johan
Published: May 2011

We study the behavior of the linewidth of a nanocontact based spin torque oscillator (STO) under application of a radio frequency (100 MHz) modulating current. We achieve a significant (up to 85%) reduction in the STO linewidth when it is modulated across a region of high nonlinearity. The mechanism responsible for the linewidth reduction is the nonlinear frequency shift under the influence of current modulation, which reduces the nonlinear amplification of the linewidth. The reduction in the linewidth during modulation can be quantitatively calculated from the free-running behavior of the STO.
Memory effects and carrier transport mechanisms of write-once- read-many-times memory devices fabricated using poly(3-hexylthiophene) molecules embedded in a polymethylmethacrylate layer on a flexible substrate
Authors: Park Keun Kab , Jung Jae Hun , Kim Tae Whan
Published: May 2011

The memory effects and the carrier transport mechanisms of write-once-read-many-times (WORM) memory devices fabricated using poly(3-hexylthiophene) (P3HT) molecules embedded in a polymethylmethacrylate (PMMA) polymer layer on a flexible substrate were investigated. Current-voltage (I-V) curves at 300 K for Al/P3HT:PMMA/indium-tin-oxide WORM device showed a permanent memory behavior with an ON/OFF ratio of 104. The estimated retention time of the ON state of the WORM device was more than 10 years. The carrier transport mechanisms of the WORM memory devices are described using several models to fit the experimental I-V data.
Atom probe analysis of interfacial abruptness and clustering within a single InxGa1−xN quantum well device on semipolar (101¯1¯) GaN substrate
Authors: Prosa T. J. , Clifton P. H. , Zhong H. , Tyagi A. , Shivaraman R. , DenBaars S. P. , Nakamura S. , Speck J. S.
Published: May 2011

Pulsed laser atom probe tomography (APT) of InxGa1−xN single quantum well (SQW) grown on semipolar (101¯1¯) GaN orientation estimates the interior atomic composition within the SQW at 6.5±0.7 at. % In, 46.2±0.7 at. % Ga, and 47.3±0.7 at. % N. The atom probe analysis is performed in both “top-down” and “cross-section” orientations. Self-consistent Schrödinger–Poisson simulation employing structural and compositional parameters obtained from APT results estimates the polarization field within the SQW at 720 kV/cm. A statistical method for the evaluation of indium homogeneity within the SQW is also considered.
Charge carrier lifetime in boron carbide thin films
Authors: Bao Ruqiang , Yan Zijie , Chrisey Douglas B.
Published: May 2011

Charge carrier lifetime is a critical parameter to improve the conversion efficiency of radioisotope power sources and the sensitivity of neutron detectors based on boron carbide thin films. The effective charge carrier lifetime in B4C boron carbide films has been investigated by using transient photoconductivity decay. The carrier lifetime depends on the characterization conditions as well as the structure of the films. The measured lifetime could be up to ∼1 ms in B4C film, which is much longer than that in conventional semiconductors. The photoresistance change in B4C films and the photovoltaic response of B4C/n-Si(100) heterojunctions have also been studied.
Control of threshold voltage in low-voltage organic complementary inverter circuits with floating gate structures
Authors: Yokota Tomoyuki , Nakagawa Takashi , Sekitani Tsuyoshi , Noguchi Yoshiaki , Fukuda Kenjiro , Zschieschang Ute , Klauk Hagen , Takeuchi Ken , Takamiya Makoto , Sakurai Takayasu , Someya Takao
Published: May 2011

We have demonstrated threshold-voltage control of p- and n-channel organic transistors with a floating-gate structure and self-assembled monolayer-based gate dielectrics and applied this technique to tune the switching voltage of organic complementary inverters. The threshold voltages of the p- and n-channel transistors are changed independently and systematically across a wide range from +2.4 to –1 V and from –0.3 to +1.5 V, respectively, when the program voltages of –6 V and +6 V are applied to the p- and n-channel transistors, respectively. Furthermore, we fabricated tunable organic complementary inverters, and ring oscillators whose oscillations are controlled by varying floating-gate charges.
Energy transition characterization of 1.18 and 1.3 μm bands of bismuth fiber by spectroscopy of the transient oscillations
Authors: Gumenyuk Regina , Golant Konstantin , Okhotnikov Oleg G.
Published: May 2011

The experimental evidence of laser transition type in bismuth-doped silica fibers operating at different spectral bands is presented. Spectrally resolved transient (relaxation) oscillations studied for a Bi-doped fiber laser at room and liquid-nitrogen temperatures allow to identify the three- and four-level energy bands. 1.18 μm short-wavelength band is found to be a three-level system at room temperature with highly populated terminal energy level of laser transition. The depopulation of ground level by cooling the fiber down to liquid-nitrogen temperature changes the transition to four-level type. Four-level energy transition distinguished at 1.32 μm exhibits the net gain at room temperature.
Equilibrium states of homogeneous sheared compressible turbulence
Authors: Riahi M. , Lili T.
Published: May 2011

Equilibrium states of homogeneous compressible turbulence subjected to rapid shear is studied using rapid distortion theory (RDT). The purpose of this study is to determine the numerical solutions of unsteady linearized equations governing double correlations spectra evolution. In this work, RDT code developed by authors solves these equations for compressible homogeneous shear flows. Numerical integration of these equations is carried out using a second-order simple and accurate scheme. The two Mach numbers relevant to homogeneous shear flow are the turbulent Mach number Mt, given by the root mean square turbulent velocity fluctuations divided by the speed of sound, and the gradient Mach number Mg which is the mean shear rate times the transverse integral scale of the turbulence divided by the speed of sound. Validation of this code is performed by comparing RDT results with direct numerical simulation (DNS) of [A. Simone, G.N. Coleman, and C. Cambon, Fluid Mech. 330, 307 (1997)] and [S. Sarkar, J. Fluid Mech. 282, 163 (1995)] for various values of initial gradient Mach number Mg0. It was found that RDT is valid for small values of the non-dimensional times St (St < 3.5). It is important to note that RDT is also valid for large values of St (St > 10) in particular for large values of Mg0. This essential feature justifies the resort to RDT in order to determine equilibrium states in the compressible regime.
Counting individual DNA molecules by the stochastic attachment of diverse labels
Authors: Fu Glenn K. , Hu Jing , Wang Pei-Hua , Fodor Stephen P. A.
Published: May 2011

We implement a unique strategy for single molecule counting termed stochastic labeling, where random attachment of a diverse set of labels converts a population of identical DNA molecules into a population of distinct DNA molecules suitable for threshold detection. The conceptual framework for stochastic labeling is developed and experimentally demonstrated by determining the absolute and relative number of selected genes after stochastically labeling approximately 360,000 different fragments of the human genome. The approach does not require the physical separation of molecules and takes advantage of highly parallel methods such as microarray and sequencing technologies to simultaneously count absolute numbers of multiple targets. Stochastic labeling should be particularly useful for determining the absolute numbers of RNA or DNA molecules in single cells.
Breaking the regioselectivity rule for acrylate insertion in the Mizoroki–Heck reaction
Authors: Wucher Philipp , Caporaso Lucia , Roesle Philipp , Ragone Francesco , Cavallo Luigi , Mecking Stefan , Göttker-Schnetmann Inigo
Published: May 2011

In modern methods for the preparation of small molecules and polymers, the insertion of substrate carbon–carbon double bonds into metal–carbon bonds is a fundamental step of paramount importance. This issue is illustrated by Mizoroki–Heck coupling as the most prominent example in organic synthesis and also by catalytic insertion polymerization. For unsymmetric substrates H
2
C = CHX the regioselectivity of insertion is decisive for the nature of the product formed. Electron-deficient olefins insert selectively in a 2,1-fashion for electronic reasons. A means for controlling this regioselectivity is lacking to date. In a combined experimental and theoretical study, we now report that, by destabilizing the transition state of 2,1-insertion via steric interactions, the regioselectivity of methyl acrylate insertion into palladium–methyl and phenyl bonds can be inverted entirely to yield the opposite “regioirregular” products in stoichiometric reactions. Insights from these experiments will aid the rational design of complexes which enable a catalytic and regioirregular Mizoroki–Heck reaction of electron-deficient olefins.
KP solitons, total positivity, and cluster algebras
Authors: Kodama Yuji , Williams Lauren K.
Published: May 2011

Soliton solutions of the KP equation have been studied since 1970, when Kadomtsev and Petviashvili [Kadomtsev BB, Petviashvili VI (1970)
Sov Phys Dokl
15:539–541] proposed a two-dimensional nonlinear dispersive wave equation now known as the KP equation. It is well-known that the Wronskian approach to the KP equation provides a method to construct soliton solutions. The
regular
soliton solutions that one obtains in this way come from points of the totally nonnegative part of the Grassmannian. In this paper we explain how the theory of total positivity and cluster algebras provides a framework for understanding these soliton solutions to the KP equation. We then use this framework to give an explicit construction of certain soliton contour graphs and solve the inverse problem for soliton solutions coming from the totally positive part of the Grassmannian.
Origins of saccharide-dependent hydration at aluminate, silicate, and aluminosilicate surfaces
Authors: Smith Benjamin J. , Rawal Aditya , Funkhouser Gary P. , Roberts Lawrence R. , Gupta Vijay , Israelachvili Jacob N. , Chmelka Bradley F.
Published: May 2011

Sugar molecules adsorbed at hydrated inorganic oxide surfaces occur ubiquitously in nature and in technologically important materials and processes, including marine biomineralization, cement hydration, corrosion inhibition, bioadhesion, and bone resorption. Among these examples, surprisingly diverse hydration behaviors are observed for oxides in the presence of saccharides with closely related compositions and structures. Glucose, sucrose, and maltodextrin, for example, exhibit significant differences in their adsorption selectivities and alkaline reaction properties on hydrating aluminate, silicate, and aluminosilicate surfaces that are shown to be due to the molecular architectures of the saccharides. Solid-state
1
H,
13
C,
29
Si, and
27
Al nuclear magnetic resonance (NMR) spectroscopy measurements, including at very high magnetic fields (19 T), distinguish and quantify the different molecular species, their chemical transformations, and their site-specific adsorption on different aluminate and silicate moieties. Two-dimensional NMR results establish nonselective adsorption of glucose degradation products containing carboxylic acids on both hydrated silicates and aluminates. In contrast, sucrose adsorbs intact at hydrated silicate sites and selectively at anhydrous, but not hydrated, aluminate moieties. Quantitative surface force measurements establish that sucrose adsorbs strongly as multilayers on hydrated aluminosilicate surfaces. The molecular structures and physicochemical properties of the saccharides and their degradation species correlate well with their adsorption behaviors. The results explain the dramatically different effects that small amounts of different types of sugars have on the rates at which aluminate, silicate, and aluminosilicate species hydrate, with important implications for diverse materials and applications.
Temperature Dependence of Atmospheric NO3 Loss Frequency
Authors: Li Su-wen , Xie Pin-hua , Chen De-bao , Jiang En-hua , Wang Xu-de
Published: May 2011

A new indicator with temperature dependence of the NO3 loss frequency, was developed to study the contribution of NO3 to the oxidation of monoterpenes and NOx removal in the atmosphere. The new indicator arises from the temperature dependence of kinetic constant. The new indicator was applied to data of observation based on differential optical absorption spectroscopy system on the outskirts of Hefei, China. According to the findings, the contribution of monoterpenes to the loss of NO3 was 70%–80%.
TR-ESR Investigation on Reaction of Vitamin C with Excited Triplet of 9,10-phenanthrenequinone in Reversed Micelle Solutions
Authors: Xu Xin-sheng , Shi Lei , Liu Yi , Ji Xue-han , Cui Zhi-feng
Published: May 2011

Time-resolved electron spin resonance has been used to study quenching reactions between the antioxidant Vitamin C (VC) and the triplet excited states of 9,10-phenanthrenequinone (PAQ) in ethylene glycol-water (EG-H2O) homogeneous and inhomogeneous reversed micelle solutions. Reversed micelle solutions were used to be the models of physiological environment of biological cell and tissue. In PAQ/EG-H2O homogeneous solution, the excited triplet of PAQ (3PAQ*) abstracts hydrogen atom from solvent EG. In PAQ/VC/EG-H2O solution, 3PAQ* abstracts hydrogen atom not only from solvent EG but also from VC. The quenching rate constant of 3PAQ* by VC is close to the diffusion-controlled value of 1.41 × 108 L/(mol ·s). In hexadecyltrimethylammonium bromide (CTAB)/EG-H2O and aerosol OT (AOT)/EG-H2O reversed micelle solutions, 3PAQ* and VC react around the water-oil interface of the reversed micelle. Exit of 3PAQ* from the lipid phase slows down the quenching reaction. For Triton X-100 (TX-100)/EG-H2O reversed micelle solution, PAQ and VC coexist inside the hydrophilic polyethylene glycol core, and the quenching rate constant of 3PAQ* by VC is larger than those in AOT/EG-H2O and CTAB/EG-H2O reversed micelle solutions, even a little larger than that in EG-H2O homogeneous solution. The strong emissive chemically induced dynamic electron polarization of As.− resulted from the effective TM spin polarization transfer in hydrogen abstraction of 3PAQ* from VC.
Effects of Size and Microstructures on Infrared Spectra of Pyrolusites
Authors: Cai Ruo-yu , Wang Wen-lou , Jiang Heng , Shi Lei , He Bo , Wei Shi-qiang
Published: May 2011

Nanofibrous pyrolusite (β-MnO2) was synthesized. The particle shape changes from nanofibers to nanoparticles after grinding, and the phase structure does not change. The local environment around the central manganese ion has a slight change in nanoparticles related to nanofibers. Fourier transform infrared (FTIR) spectra showed that A2u mode frequency shifts from 514 cm−1 to 574 cm−1 to 617 cm−1 gradually while the particle shape and size change from long nanofibers to short fibers and to nanoparticles. The extra vibrational band that is unpredicted by factor group analysis originates from the contribution of A2u mode of the particles with different sizes and shapes in the studied sample. On the basis of Rietveld refinement analysis of XRD profiles and the FTIR spectra, we think that two kinds of MnO6 octahedral geometries, i.e., 4 long+2 short and 4 short+2 long, could exist in pyrolusites synthesized by different route. The maximum vibrational frequency in the FTIR spectra of pyrolusites is sensitive to these micro-structures. Assignment of four vibrational bands in the middle and far infrared region has been made.
Molecular Dynamics Study of RDX/AMMO Propellant
Authors: Li Miao-miao , Li Feng-sheng , Shen Rui-qi
Published: May 2011

Molecular dynamics simulations have been performed to investigate well-known energetic material cyclotrimethylene trinitramine (RDX) crystal, 3-azidomethyl-3-methyloxetane (AMMO) and RDX/AMMO propellant. The results show that the binding energies on different crystalline surface of RDX changes in the order of (010) > (100) > (001). The interactions between RDX and AMMO have been analyzed by means of pair correlation functions. The mechanical properties of RDX/AMMO propellant, i.e. elastic coefficients, modulus, Cauchy pressure, and Poisson's ratio, etc., have been obtained. It is found that mechanical properties are effectively improved by adding some amounts of AMMO polymers, and the overall effect of AMMO on three crystalline surfaces of RDX changes in the order of (100) > (010) > (001). The energetic properties of RDX/AMMO propellant have also been calculated and the results show that compared with the pure RDX crystal, the standard theoretical specific impulse of RDX/AMMO propellant decrease, but they are still superior to those of double base propellant.
Electron Attachment Studies for CHCl3 Using Ion Mobility Spectrometry
Authors: Han Hai-yan , Feng Hong-tao , Li Hu , Wang Hong-mei , Jiang Hai-he , Chu Yan-nan
Published: May 2011

The dissociative electron attachment process for CHCl3 at different electric field have been studied with nitrogen as drift and carrier gas using corona discharge ionization source ion mobility spectrometry (CD-IMS). The corresponding electron attachment rate constants varied from 1.26×10−8 cm3/(molecules s) to 8.24×10−9 cm3/(molecules s) as the electric field changed from 200 V/cm to 500 V/cm. At a fixed electric field in the drift region, the attachment rate constants are also detected at different sample concentration. The ion-molecule reaction rate constants for the further reaction between Cl− and CHCl3 are also detected, which indicates that the technique maybe becomes a new method to research the rate constants between ions and neural molecules. And the reaction rate constants between Cl− and CHCl3 are the first time detected using CD-IMS.
Modeling Study of Hydrogen/Oxygen andn-alkane/Oxygen Counterflow Diffusion Flames
Authors: Wang Xiao-wei , Cai Guo-biao , Yang Vigor
Published: May 2011

A comprehensive analysis of hydrogen/oxygen and hydrocarbon/oxygen counterflow diffusion flames has been conducted using corresponding detailed reaction mechanisms. The hydrocarbon fuels contain n-alkanes from CH4 to C16H34. The basic diffusion flame structures are demonstrated, analyzed, and compared. The effects of pressure, and strain rate on the flame behavior and energy-release rate for each fuel are examined systematically. The detailed chemical kinetic reaction mechanisms from Lawrence Livermore National Laboratory (LLNL) are employed, and the largest one of them contains 2115 species and 8157 reversible reactions. The results indicate for all of the fuels the flame thickness and heat release rate correlate well with the square root of the pressure multiplied by the strain rate. Under the condition of any strain rate and pressure, H2 has thicker flame than hydrocarbons, while the hydrocarbons have the similar temperature and main products distributions and almost have the same flame thickness and heat release rate. The result indicates that the fuels composed with these hydrocarbons will still have the same flame properties as any pure n-alkane fuel.
A Colorimetric Receptor Based on Schiff-Base Bearing Azo-Phenolic Hydroxy Group
Authors: Liu Ge , Shao Jie
Published: May 2011

A novel N-(2-hydroxy-5-chlorodibenzophenone)-N′-[2-hydroxy-5-azophenyl-benzaldehyde]-1,2-diaminobenzene receptor has been synthesized by simple steps with good yields. The anion recognition properties were studied by ultraviolet-visible spectroscopy. The results showed that the receptor had a higher affinity to F−, AcO−, and H2PO4−, but no evident binding with Cl−, Br−, and I−. Upon addition of the three former anions to the receptors in DMSO, the solution exhibited an obvious color change from colorless to yellow, which could be observed by the naked eye, thus the receptor could act as a fluoride ion sensor even in the presence of other halide ions. The UV-Vis data indicates that a 1:1 stoichiometric complex is formed through hydrogen bonding interactions between receptor and anions.
Water-promoted One-step Anodic Acetoxylation of Benzene to Phenyl Acetate with High Selectivity
Authors: Pei Juan , Qin Song , Li Gui-ying , Hu Chang-wei
Published: May 2011

One-step anodic acetoxylation of benzene to phenyl acetate was studied in acetic acid-water solution using a one-compartment electrochemical cell in galvanostatic mode. Compared to the anhydrous system, the addition of water improved the current efficiency for the electro-synthesis of phenyl acetate. The maximum efficiency reached 4.8% with the selectivity of 96% to phenyl acetate when the electrolysis was carried out under the optimal conditions. The investigation also indicated that the concentration of phenyl acetate increased linearly in 12 h and reached 1.07 g/L with the selectivity of 95%. Cyclic voltammetry experiments showed that the adsorption of benzene at Pt anode enhanced by the addition of water was critical to the formation of phenyl acetate. An activated benzene mechanism was proposed for the anodic acytoxylation, and the analysis of gas products demonstrated that Kolbe reaction was the main side reaction.
Dualities for self–small groups
Authors: Breaz Simion , Schultz Phill
Published: May 2011

We construct a family of dualities on some subcategories of the quasi-category

S

\mathcal {S}

of self-small groups of finite torsion-free rank which cover the class

S

\mathcal {S}

. These dualities extend several of those in the literature. As an application, we show that a group

A
∈

S

A\in \mathcal {S}

is determined up to quasi–isomorphism by the

Q

\mathbb {Q}

–algebras

{

Q

Hom
⁡
(
C
,
A
)
:

C
∈

S

}

\{\mathbb {Q}\operatorname {Hom}(C,A):\,C\in \mathcal {S}\}

and

{

Q

Hom
⁡
(
A
,
C
)
:

C
∈

S

}

\{\mathbb {Q}\operatorname {Hom}(A,C):\,C\in \mathcal {S}\}

. We also generalize Butler’s Theorem to self-small mixed groups of finite torsion-free rank.
A nuclear factor-κB signaling pathway via protein kinase C δ regulates replication of respiratory syncytial virus in polarized normal human nasal epithelial cells
Authors: Masaki Tomoyuki , Kojima Takashi , Okabayashi Tamaki , Ogasawara Noriko , Ohkuni Tsuyoshi , Obata Kazufumi , Takasawa Akira , Murata Masaki , Tanaka Satoshi , Hirakawa Satoshi , Fuchimoto Jun , Ninomiya Takafumi , Fujii Nobuhiro , Tsutsumi Hiroyuki , Himi Tetsuo , Sawada Norimasa
Published: May 2011

Respiratory syncytial virus (RSV) is the major cause of bronchitis, asthma, and severe lower respiratory tract disease in infants and young children. The airway epithelium, which has a well-developed barrier regulated by tight junctions, is the first line of defense during respiratory virus infection. In upper airway human nasal epithelial cells (HNECs), however, the primary site of RSV infection, the mechanisms of replication and budding of RSV, and the epithelial cell responses, including the tight junctional barrier, remain unknown. To investigate the detailed mechanisms of replication and budding of RSV in HNECs and the epithelial cell responses, we established an RSV-infected model using human telomerase reverse transcriptase–-transfected HNECs. We first found that the expression and barrier function of tight junction molecules claudin-4 and occludin were markedly induced together with production of proinflammatory cytokines interleukin 8 and tumor necrosis factor-α in HNECs after RSV infection, and the induction of tight junction molecules possibly contributed to budding of RSV. Furthermore, the replication and budding of RSV and the epithelial cell responses in HNECs were regulated via a protein kinase C δ/hypoxia-inducible factor-1α/nuclear factor-κB pathway. The control of this pathway in HNECs may be useful not only for prevention of replication and budding of RSV, but also in therapy for RSV-induced respiratory pathogenesis.