bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of stratosphere‐troposphere exchange during the Meiyu season
Authors: Luo Jiali , Tian Wenshou , Pu Zhaoxia , Zhang Peiqun , Shang Lin , Zhang Min , Hu Jun
Published: November 2012

Characteristics of stratosphere‐troposphere exchange (STE) during the Meiyu season in the Yangtze‐Huaihe valley, China, is investigated using the European Centre for Medium‐Range Weather Forecasts interim reanalysis data, National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data, Meiyu records from the National Climate Center of China, the data from a trajectory model, and a general circulation model (GCM). Results show increases in potential vorticity and decreases in specific humidity in the upper troposphere and lower stratosphere (UTLS) before Meiyu onset, suggesting a strong downward transport of air masses around the tropopause that can be attributed to frequent tropopause folds over the Meiyu area. The minimum tropopause height occurs 3 days before Meiyu onset and then rises until about 6 days afterward. The downward cross‐tropopause mass transport (CTMF) is evidenced before Meiyu onset, which is mainly caused by the sharp meridional gradients in the tropopause pressure over the Meiyu area. After Meiyu onset, the upward cross‐tropopause transport intensifies due to enhanced convections. The analysis also suggests the strongest upward transport in the UTLS occurs northeast of the Meiyu region, within the core of the upper tropospheric westerly jet. Results from a trajectory model indicate that the lower stratospheric air intrudes into the troposphere before Meiyu onset. The significant upward movements of the middle tropospheric air are notable after Meiyu onset. As convections are weak and the upper level westerly jet is located far to the Meiyu area in poor Meiyu years, the upward CTMF over the Meiyu region is weaker during the Meiyu season compared with that in rich Meiyu years.
Increased summer rainfall in northwest Australia linked to southern Indian Ocean climate variability
Authors: Feng Juan , Li Jianping , Xu Hanlie
Published: November 2012

Although annual rainfall over most of Australia has followed a continuously decreasing trend over the past 6 decades (i.e., 1948–2007), summer rainfall in northwest Australia (NWA) has followed a pronounced increasing trend, with a significant linear trend of 2.65 mm/yr. This study investigates the causes of increasing rainfall over NWA and focuses on influences originating in the middle to high latitudes, i.e., southern Indian Ocean climate variability. Our results indicate that variations in summer rainfall over NWA are related to the concurrent strength of the Mascarene high. In years with a strong Mascarene high in the lower troposphere, the cyclonic vorticity over NWA is enhanced, and more moisture is transported into NWA. Simultaneously, an anomalous vertical closed circulation forms, with an ascending branch over NWA and subsidence over the region occupied by the Mascarene high. As for the upper troposphere, the Mascarene high is related to a teleconnection wave train from the southern Indian Ocean to NWA, which in turn influences the circulation over NWA. This setting is favorable for enhanced rainfall over NWA. Analysis of the cause of variations in the Mascarene high indicates that underlying external forcing of the high by, for example, sea surface temperature (SST) has intensified, possibly due to the influence of the southern annular mode (SAM) during the preceding spring. This mechanism was further examined using numerical experiments. We believe that the strengthening of the Mascarene high, which is caused by the enhanced SST gradient within the southern Indian Ocean associated with the preceding (upward) SAM, has had a significant influence on the increase in summer rainfall over NWA.
The design and proof of concept for a CD8+ T cell‐based vaccine inducing cross‐subtype protection against influenza A virus
Authors: Tan Amabel C L , Deliyannis Georgia , Bharadwaj Mandvi , Brown Lorena E , Zeng Weiguang , Jackson David C
Published: November 2012

In this study, we examined the reactivity of human peripheral blood mononuclear cells to a panel of influenza A virus (IAV) CD8+ T‐cell epitopes that are recognised by the major human leukocyte antigen (HLA) groups represented in the human population. We examined the level of recognition in a sample of the human population and the potential coverage that could be achieved if these were incorporated into a T‐cell epitope‐based vaccine. We then designed a candidate influenza vaccine that incorporated three of the examined HLA‐A2‐restricted influenza epitopes into Pam2Cys‐based lipopeptides. These lipopeptides do not require the addition of an adjuvant and can be delivered directly to the respiratory mucosa enabling the generation of local memory cell populations that are crucial for clearance of influenza. Intranasal administration of a mixture of three lipopeptides to HLA‐A2 transgenic HHD mice elicited multiple CD8+ T‐cell specificities in the spleen and lung that closely mimicked the response generated following natural infection with influenza. These CD8+ T cells were associated with viral reduction following H3N1 influenza virus challenge for as long as 3 months after lipopeptide administration. In addition, lipopeptides containing IAV‐targeting epitopes conferred substantial benefit against death following infection with a virulent H1N1 strain. Because CD8+ T cell epitopes are often derived from highly conserved regions of influenza viruses, such vaccines need not be reformulated annually and unlike current antibody‐inducing vaccines could provide cross‐protective immunity against newly emerging pandemic viruses.
Mesenchymal stromal cells and regulatory T cells: the Yin and Yang of peripheral tolerance?
Authors: Burr Stephen P , Dazzi Francesco , Garden Oliver A
Published: November 2012

In recent years, mesenchymal stromal cells (MSCs) and regulatory T cells (Tregs) have both garnered significant interest from immunologists worldwide, not least because of the potential application of both cell types in the treatment of many chronic inflammatory and autoimmune diseases. Although both MSCs and Tregs can be considered immunosuppressive in their own right, the induction of Tregs by activated MSCs is now a well‐publicised phenomenon; however, only recently have the mechanisms involved in this induction started to become clear. Indeed, it is becoming increasingly apparent that there exists a complex interplay between the two lineages leading to this potent inhibition of the host immune response. Cell contact, soluble mediators—including prostaglandin E2 and transforming growth factor β—and indirect induction via manipulation of other antigen‐presenting cells all appear to have vital roles in the interactions between MSCs and Tregs. Much still remains to be discovered before we have a full understanding of this important aspect of the immune response, but there have already been a multitude of clinical trials suggesting that MSC/Treg therapies could offer significant benefits in the treatment of both autoimmune disease and graft versus host disease. Although these therapies are still in their infancy, the synergy between MSCs and Tregs will undoubtedly yield future breakthroughs in the treatment of many debilitating conditions and usher in a new wave of targeted, cell‐based therapeutics.
Cry1Aa binding to the cadherin receptor does not require conserved amino acid sequences in the domain II loops
Authors: Fujii Yuki , Tanaka Shiho , Otsuki Manami , Hoshino Yasushi , Morimoto Chinatsu , Kotani Takuya , Harashima Yuko , Endo Haruka , Yoshizawa Yasutaka , Sato Ryoichi
Published: November 2012

Characterizing the binding mechanism of Bt (Bacillus thuringiensis) Cry toxin to the cadherin receptor is indispensable to understanding the specific insecticidal activity of this toxin. To this end, we constructed 30 loop mutants by randomly inserting four serial amino acids covering all four receptor binding loops (loops α8, 1, 2 and 3) and analysed their binding affinities for Bombyx mori cadherin receptors via Biacore. High binding affinities were confirmed for all 30 mutants containing loop sequences that differed from those of wild-type. Insecticidal activities were confirmed in at least one mutant from loops 1, 2 and 3, suggesting that there is no critical amino acid sequence for the binding of the four loops to BtR175. When two mutations at different loops were integrated into one molecule, no reduction in binding affinity was observed compared with wild-type sequences. Based on these results, we discussed the binding mechanism of Cry toxin to cadherin protein.
Single-Subject Experimental Design for Evidence-Based Practice
Authors: Byiers Breanne J. , Reichle Joe , Symons Frank J.
Published: November 2012

Purpose

Single-subject experimental designs (SSEDs) represent an important tool in the development and implementation of evidence-based practice in communication sciences and disorders. The purpose of this article is to review the strategies and tactics of SSEDs and their application in speech-language pathology research.

Method

The authors discuss the requirements of each design, followed by advantages and disadvantages. The logic and methods for evaluating effects in SSED are reviewed as well as contemporary issues regarding data analysis with SSED data sets. Examples of challenges in executing SSEDs are included. Specific exemplars of how SSEDs have been used in speech-language pathology research are provided throughout.

Conclusion

SSED studies provide a flexible alternative to traditional group designs in the development and identification of evidence-based practice in the field of communication sciences and disorders.
A Historical Review of the Information Technology and Business Process Captive Centre Sector
Authors: Oshri Ilan , van Uhm Bob
Published: November 2012

A captive centre is a business unit that is owned and provides services to the parent firm from an offshore location. In this paper we seek to apply a historical perspective in order to understand what factors shaped its development path. In particular we are interested to document and explain changes that took place in the captive sector vis-a-vis extant country attractiveness frameworks. To achieve this objective, we examine changes that multinationals introduced in their offshore captive investments concerning the type of the captive they set up, the functions they offshored through a captive centre and to which location. Information was collected from secondary sources on offshore captive investments made by Fortune 250 global firms between 1985 and 2010. On the basis of the analysis the paper considers the importance of disrupting factors to the extant country selection literature.
Streamwise forced oscillations of circular and square cylinders
Authors: Tudball-Smith Daniel , Leontini Justin S. , Sheridan John , Jacono David Lo
Published: November 2012

The modification of a cylinder wake by streamwise oscillation of the cylinder at the vortex shedding frequency of the unperturbed cylinder is reported. Recent numerical simulations [J. S. Leontini, D. Lo Jacono, and M. C. Thompson, “A numerical study of an inline oscillating cylinder in a free stream,” J. Fluid Mech. 688, 551–568 (2011)10.1017/jfm.2011.403] showed that this forcing results in the primary frequency decreasing proportionally to the square of the forcing amplitude, before locking to a subharmonic at higher amplitudes. The experimental results presented here show that this behavior continues at higher Reynolds numbers, although the flow is three-dimensional. In addition, it is shown that this behavior persists when the body is a square cross section, and when the frequency of forcing is detuned from the unperturbed cylinder shedding frequency. The similarity of the results across Reynolds number, geometry, and frequency suggests that the physical mechanism is applicable to periodic forcing of the classic von Kármán vortex street, regardless of the details of the body which forms the street.
Molecular dynamics study of dynamical contact between a nanoscale tip and substrate for atomic force microscopy experiments
Authors: Kim Hojin , Venturini Gabriela , Strachan Alejandro
Published: November 2012

We propose a molecular dynamics approach to model the dynamical interaction of a nanoscale tip with a substrate under conditions relevant to dynamic atomic force microscopy (AFM). We apply this approach to a half-sphere platinum tip contacting a flat surface of the same metal and study how the input dynamical variables (loading rate during contact and nominal separation between the tip and the substrate) affect the observed interaction between the tip and the substrate. We predict the energy dissipated per cycle and study the use of force-displacement curves to extract local stiffness. We find that, when using nanoscale probes, accurate values can only be obtained for a narrow range of indentations, large enough for continuum elasticity to apply and small enough to avoid plastic deformation. Simulations using the proposed approach are expected to be useful to explore operating conditions of AFM and interpret their results.
The analytical basis for the resonances and anti-resonances of loop antennas and meta-material ring resonators
Authors: McKinley A. F. , White T. P. , Maksymov I. S. , Catchpole K. R.
Published: November 2012

Interest in the electromagnetic properties of loop structures has surged with the recent appearance of split-ring resonator meta-materials (SRRs) and nano-antennas. Understanding the resonances, anti-resonances, and harmonics of these loops is key to understanding their response to a wide range of excitation wavelengths. We present the classical analytical solution for the input impedance of a loop structure with circumference on the order of the wavelength, and we show how to identify these resonances from the function. We transform the classical solution into a new RLC formulation and show that each natural mode of the loop can be represented as a series resonant circuit, such that the full response function can be resolved by placing all of these circuits in parallel. We show how this formulation applies to SRRs.
Quantification of transition dipole strengths using 1D and 2D spectroscopy for the identification of molecular structures via exciton delocalization: Application to α-helices
Authors: Grechko Maksim , Zanni Martin T.
Published: November 2012

Vibrational and electronic transition dipole strengths are often good probes of molecular structures, especially in excitonically coupled systems of chromophores. One cannot determine transition dipole strengths using linear spectroscopy unless the concentration is known, which in many cases it is not. In this paper, we report a simple method for measuring transition dipole moments from linear absorption and 2D IR spectra that does not require knowledge of concentrations. Our method is tested on several model compounds and applied to the amide I′ band of a polypeptide in its random coil and α-helical conformation as modulated by the solution temperature. It is often difficult to confidently assign polypeptide and protein secondary structures to random coil or α-helix by linear spectroscopy alone, because they absorb in the same frequency range. We find that the transition dipole strength of the random coil state is 0.12 ± 0.013 D2, which is similar to a single peptide unit, indicating that the vibrational mode of random coil is localized on a single peptide unit. In an α-helix, the lower bound of transition dipole strength is 0.26 ± 0.03 D2. When taking into account the angle of the amide I′ transition dipole vector with respect to the helix axis, our measurements indicate that the amide I′ vibrational mode is delocalized across a minimum of 3.5 residues in an α-helix. Thus, one can confidently assign secondary structure based on exciton delocalization through its effect on the transition dipole strength. Our method will be especially useful for kinetically evolving systems, systems with overlapping molecular conformations, and other situations in which concentrations are difficult to determine.
Weak commutation relations of unbounded operators: Nonlinear extensions
Authors: Bagarello Fabio , Inoue Atsushi , Trapani Camillo
Published: November 2012

We continue our analysis of the consequences of the commutation relation \documentclass[12pt]{minimal}\begin{document}$[S, T]\break = {\bb 1}$\end{document}[S,T]=1, where S and T are two closable unbounded operators. The weak sense of this commutator is given in terms of the inner product of the Hilbert space \documentclass[12pt]{minimal}\begin{document}${\mathcal {H}},$\end{document}H, where the operators act. We also consider what we call, adopting a physical terminology, a nonlinear extension of the above commutation relations.
Optical modeling of laser ablated microstructures
Authors: Gower M. C. , Davies E. , Holmes A. S.
Published: November 2012

From only an a priori knowledge of the optical parameters of a laser beam, the delivery system together with a substrate's material properties, a ray-tracing model capable of predicting the 3-D topology of micro/nanostructures machined by pulsed laser ablation has been developed. The model includes secondary illumination effects produced by the microstructure created by successive pulses (wall reflections, refraction, wave guiding, shadowing, etc.) as well as the complete optical properties of the beam delivery system. We have used material ablation by pulsed excimer lasers and associated beam delivery systems to demonstrate some of the capabilities of the model. Good agreement is obtained between computations and experimental results in terms of the predicted ablation depth per pulse and the wall taper angle of channels and holes. The model can predict ablated profiles of holes and indicate the most efficient drilling strategy in terms of material removal rates. The model also shows diffraction effects are not required to explain the tapering vertical walls observed when ablating microstructures. Finally, the model has been used to demonstrate aberrations in an optical imaging system limiting the creation of submicron features in an ablated microstructure. Provided photons are absorbed linearly in a substrate according to Beer's law with negligible thermal diffusion effects, the model is equally applicable to using other types of pulsed laser sources and systems with imaged or focused beams.
A comparison of the solvation thermodynamics of amino acid analogues in water, 1-octanol and 1-n-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids by molecular simulation
Authors: Paluch Andrew S. , Vitter Cameron A. , Shah Jindal K. , Maginn Edward J.
Published: November 2012

A computational approach is developed to quantitatively study the solvation thermodynamics of amino acid analogues in ionic liquids via molecular simulation. The solvation thermodynamics of amino acid analogues in ionic liquids is important for an understanding of protein-ionic liquid interactions, shedding insight into the structure and solubility of proteins, and the activity of enzymes in ionic liquids. This information is additionally key to developing novel extraction processes. As a result of the challenge of quantitatively describing the solvation behavior of ionic liquids, a key outcome of the present study is the development of a “hydrophobicity” scale to quantitatively describe the amino acid analogues. The scale allows one to separate the results of both the hydrophobic and hydrophillic analogues, simplifying an understanding of the observed trends. Equipped with the proposed hydrophobicity scale, one needs only perform conventional solvation free energy calculations of the amino acid analogues in the ionic liquids of interest. The necessary simulation tools are available in most open-source simulation software, facilitating the adoption of this approach by the simulation community at large. We have studied the case of varying the cation alkyl-chain length of a 1-n-alkyl-3-methylimidazolium cation paired with the bis(trifluoromethylsulfonyl)imide anion. The findings suggest that a judicious selection of both the cation and anion could potentially lead to a solvent for which the amino acid analogues have an affinity far greater than that for both water and a non-polar reference solvent.
Comparative analysis of energy security in the Nordic countries: The role of renewable energy resources in diversification
Authors: Aslani Alireza , Antila Erkki , Wong Kau-Fui V.
Published: November 2012

Security of energy supply has been one of the important debates among citizens and governments of the Nordic countries after the first energy crisis. In response, diversification was defined as the heart strategy to reach a certain level of energy supply. This article discusses about the level of energy security in the Nordic countries with comparison to other developed countries and their neighbors. Then, the support schemes and policies to achieve the energy security and diversification are reviewed based on the system thinking approach with especial focus on the renewable energy resources. This approach provides a unique and powerful tool to explain the complexity and the relationships among the elements of the support schemes in the energy security analysis.
Antenna-enhanced infrared near-field nanospectroscopy of a polymer
Authors: Mattis Hoffmann Jón , Hauer Benedikt , Taubner Thomas
Published: November 2012

Scattering-type scanning near-field optical microscopy (s-SNOM) allows for optical nanoscale imaging and provides information about topographical and chemical material properties with subwavelength resolution. In this letter, we demonstrate that the sensitivity of s-SNOM can be improved by means of infrared resonant antennas. This technique is comparable to the application of resonant nanostructures in far-field surface-enhanced infrared spectroscopy. We find that the near-field amplitude spectra of the polymer poly(ethyl methacrylate) obtained on resonant structures are increased in absolute value as well as in contrast over those obtained on non-resonant, highly reflective materials such as gold.
Obtaining material identification with cosmic ray radiography
Authors: Morris C. L. , Borozdin Konstantin , Bacon Jeffrey , Chen Elliott , Lukić Zarija , Milner Edward , Miyadera Haruo , Perry John , Schwellenbach Dave , Aberle Derek , Dreesen Wendi , Green J. Andrew , McDuff George G. , Nagamine Kanetada , Sossong Michael , Spore Candace , Toleman Nathan
Published: November 2012

The passage of muons through matter is dominated by the Coulomb interaction with electrons and nuclei in the matter. The muon interaction with the electrons leads to continuous energy loss and stopping of the muons. The muon interaction with nuclei leads to angular diffusion. Using both stopped muons and angle diffusion interactions allows us to determine density and identify materials. Here we demonstrate material identification using data taken at Los Alamos with a particle tracker built from a set of sealed drift tubes with commercial electronics and software, the Mini Muon Tracker (MMT).
Thermal boundary layer analysis corresponding to droplet train impingement
Authors: Trujillo Mario F. , Lewis Steven R.
Published: November 2012

Simulations of droplet train impingement on a pre-wetted solid surface heated from below are used to study the thermal boundary layer behavior over a parameter space which includes variations in Reynolds, Peclet, and Weber numbers, as well as variations in inter-droplet spacing and initial liquid film thickness. Computationally, a modified version of the Volume-of-Fluid method is developed and employed in this study. The solver is validated against closed form solutions and additional experimental data from the literature. In combination with the simulations, an analytical representation is also developed and compared to the computations yielding favorable agreement. Results show that the boundary layer thickness is mostly affected by changes in inter-droplet spacing, Reynolds, and Peclet number, and influenced minimally by variations in Weber number and initial film thickness. In fact, it is explicitly demonstrated in the analysis that the impact velocity has the greatest effect in local heat transfer. An analytical expression for the Nusselt number radial profile is also developed. It shows that the Nusselt number scales as ∼ Re1/2, and its radial dependence is \documentclass[12pt]{minimal}\begin{document}$\sim \sqrt{r}$\end{document}∼r, which is the same as the circular jet impingement case. The notable difference in the present Nusselt number relationship is the role of inter-droplet spacing, which plays a significant role in the current configuration.
Hard ferromagnetism in melt-spun Hf2Co11B alloys
Authors: McGuire Michael A. , Rios Orlando , Ghimire Nirmal J. , Koehler Michael
Published: November 2012

Hard ferromagnetic behavior is reported for crystalline Hf2Co11B produced by melt-spinning. For the highest-performing material, remanent magnetization, intrinsic coercive field, and maximum energy product at room temperature are 6.2 kG, 4.5 kOe, and 6.7 MGOe, respectively. This is the highest reported energy product for this class of alloys, and is about half that of optimized Nd2Fe14B ribbons. The Curie temperature of both crystalline and amorphous Hf2Co11B is near 770 K. The results suggest further optimization of magnetic properties should be attainable, and indicate Hf2Co11B to be a promising material for rare-earth-free permanent magnets.
High-performance solution-processed plasmonic Ni nanochain-Al2O3 selective solar thermal absorbers
Authors: Wang Xiaoxin , Li Haofeng , Yu Xiaobai , Shi Xiaoling , Liu Jifeng
Published: November 2012

Selective solar thermal absorber coating is an important component of concentrated solar power systems. It maximizes the absorption of solar spectrum and minimizes thermal radiation losses in the mid-infrared regime. In this letter, we demonstrate a solution-processed plasmonic Ni nanochain-Al2O3 selective solar thermal absorber with a high solar absorptance >90% and a low thermal emittance loss <10%. Unlike conventional graded-index cermet coatings, the spectral selectivity is tailored by the lengths of Ni nanochains, elimating the requirement of costly vacuum deposition for stringent thickness control. These results open a path to utilize plasmonics for low-cost, high-performance solar thermal systems.
Conductance of single-atom magnetic junctions: A first-principles study
Authors: Xie Yi-qun , Li Qiang , Huang Lei , Ye Xiang , Ke San-Huang
Published: November 2012

We present a first-principles investigation to show that the contact conductance of a half conductance quantum (G0/2) found previously does not generally hold for single-atom magnetic junctions composed of a tip and an adatom adsorbed on a surface. The contact conductance of the Ni-Co/Co(111) junction is approximately G0/2, while for the Co-Co/Co(111), Ni-Ni/Ni(111), and Ni-Ni/Ni(001) junctions the contact conductances are 0.80G0, 1.55G0, and 1.77G0, respectively. The deviation from G0/2 is mainly caused by the variation of the spin-down conductance largely determined by the minority d orbitals, as the spin-up one changes little for different junctions.
Nonlinear dependence of set time on pulse voltage caused by thermal accelerated breakdown in the Ti/HfO2/Pt resistive switching devices
Authors: Cao M. G. , Chen Y. S. , Sun J. R. , Shang D. S. , Liu L. F. , Kang J. F. , Shen B. G.
Published: November 2012

Dynamic processes of resistance switching have been systemically investigated for the Ti/HfO2/Pt bipolar devices. Different transient characteristics were observed in the set and reset processes. The set process consisted of a waiting step and a following abrupt transition, whereas the reset process demonstrated a gradual resistance change. Nonlinear dependence of set time on pulse voltage was observed and explained by the thermally accelerated dielectric breakdown of local switching regions. The accumulation and dissipation effects observed for different pulse treatments strongly supported the proposed model, which suggests a possible approach to overcome the voltage-time dilemma.
High-mobility p-channel metal-oxide-semiconductor field-effect transistors on Ge-on-insulator structures formed by lateral liquid-phase epitaxy
Authors: Suzuki Yuichiro , Ogiwara Shimpei , Hosoi Takuji , Shimura Takayoshi , Watanabe Heiji
Published: November 2012

High-mobility p-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) were fabricated on germanium-on-insulator (GOI) structures formed by lateral liquid-phase epitaxy (LLPE) from the Si seed areas. It was found that appropriate rapid annealing conditions for LLPE effectively suppress intermixing at the Si seed regions and produce tensile strained single-crystalline Ge layers surrounded by SiO2 microcrucibles. We examined the electrical properties of the thin Ge layers using GOI MOSFETs with back-gate control in the p-type accumulation mode. Excellent transistor performance, such as a low off-leakage current of 1 × 10−7 μA/μm, a high on/off current ratio of 106, and high low-field hole mobility of 480 cm2/Vs, which is 2.8 times higher than that of the reference silicon-on-insulator device, was demonstrated, indicating that the LLPE method provides high-quality local GOI structures and that it is a feasible way to fabricate the next-generation Ge-based devices.
Piezoelectric nanogenerator based on zinc oxide nanorods grown on textile cotton fabric
Authors: Khan Azam , Ali Abbasi Mazhar , Hussain Mushtaque , Hussain Ibupoto Zafar , Wissting Jonas , Nur Omer , Willander Magnus
Published: November 2012

This investigation explores piezoelectricity generation from ZnO nanorods, which were grown on silver coated textile cotton fabrics using the low temperature aqueous chemical growth method. The morphology and crystal structure studies were carried out by x-ray diffraction, scanning electron microscopic and high resolution transmission electron microscopic techniques, respectively. ZnO nanorods were highly dense, well aligned, uniform in spatial distribution and exhibited good crystal quality. The generation of piezoelectricity from fabricated ZnO nanorods grown on textile cotton fabrics was measured using contact mode atomic force microscopy. The average output voltage generated from ZnO nanorods was measured to be around 9.5 mV. This investigation is an important achievement regarding the piezoelectricity generation on textile cotton fabric substrate. The fabrication of this device provides an alternative approach for a flexible substrate to develop devices for energy harvesting and optoelectronic technology on textiles.
Detecting signals buried in noise via nanowire transistors using stochastic resonance
Authors: Nishiguchi Katsuhiko , Fujiwara Akira
Published: November 2012

We demonstrate stochastic resonance (SR), which takes advantage of noise to detect a weak signal, using a field-effect transistor (FET). An FET's structure composed of a nanowire channel enables current characteristics to show strong nonlinearity, which overcomes thermal limitation, and dynamic bistability, both of which boost an effect of SR and silhouette noise from noise. Moreover, the dynamic bistability enables SR effect to be enhanced by adding common noise to multiple FETs. The FET providing such unique characteristics opens the way to use SR for practical applications.
A molecular dynamics study of the equation of state and the structure of supercooled aqueous solutions of methanol
Authors: Corradini Dario , Su Zhiqiang , Stanley H. Eugene , Gallo Paola
Published: November 2012

We perform molecular dynamics computer simulations in order to study the equation of state and the structure of supercooled aqueous solutions of methanol at methanol mole fractions xm = 0.05 and xm = 0.10. We model the solvent using the TIP4P/2005 potential and the methanol using the OPLS-AA force field. We find that for xm = 0.05 the behavior of the equation of state, studied in the P − T and P − ρ planes, is consistent with the presence of a liquid-liquid phase transition, reminiscent of that previously found for xm = 0. We estimate the position of the liquid-liquid critical point to be at T = 193 K, P = 96 MPa, and ρ = 1.003 g/cm3. When the methanol mole fraction is doubled to xm = 0.10 no liquid-liquid transition is observed, indicating its possible disappearance at this concentration. We also study the water–water and water–methanol structure in the two solutions. We find that down to low temperature methanol can be incorporated into the water structure for both xm = 0.05 and xm = 0.10.
Interference of surface plasmon polaritons excited at hole pairs in thin gold films
Authors: Häfele V. , de León-Pérez F. , Hohenau A. , Martín-Moreno L. , Plank H. , Krenn J. R. , Leitner A.
Published: November 2012

The excitation of surface plasmon polaritons by focusing a laser beam onto a hole pair in a thin gold film is studied both experimentally and theoretically. By means of leakage radiation microscopy we quantitatively measure the light-plasmon coupling efficiency as a function of the hole distance. We find a modulation of the coupling efficiency as a function of hole distance that strongly depends on the polarization direction of the incident light, in agreement with theoretical simulations.
Experimental investigations of the TE11 mode radiation from a relativistic magnetron with diffraction output
Authors: Li Wei , Liu Yong-gui , Zhang Jun , Yang Han-wu , Qian Bao-liang
Published: November 2012

Directly radiating microwaves at TE11 mode, a relativistic magnetron with diffraction output (MDO) is experimentally investigated. Two important factors, transition section and working condition, significantly affecting the microwave powers, efficiencies, and pulse durations are analyzed. The experimental results on our designed MDO show that the optimized transition section with the parameters, 46 mm in height and 70 mm in length, is beneficial for producing high power TE11 mode microwaves. Under the low applied voltage condition (less than 650 kV), the power conversion efficiency will be higher than that obtained from the high applied voltage condition. ∼24 ns of the microwave duration is a typical value under the voltage duration of 56 ns. Pulse shortens will happen if the applied voltage is higher than 650 kV. When the applied voltage reaches 880 kV, the microwave duration is only just ∼12 ns. Impendence mismatch between the accelerator and the diode is the chief reason causing the pulse shortens.
Electronic and optical properties of vacancy-doped WS2 monolayers
Authors: Wei Jian-wei , Ma Zeng-wei , Zeng Hui , Wang Zhi-yong , Wei Qiang , Peng Ping
Published: November 2012

Monolayers of tungsten disulfide doped with atomic vacancies have been investigated for the first time by density functional theory calculations. The results reveal that the atomic vacancy defects affect the electronic and optical properties of the tungsten disulfide monolayers. The strongly ionic character of the W-S bonds and the non-bonding electrons of the vacancy defects result in spin polarization near the defects. Moreover, the spin polarization of single W atomic vacancies has a larger range than for one or two S atomic vacancies. In particular, increased intensity of absorption and red shift of optical absorption are universally observed in the presence of these atomic defects, which are shown to be a fundamental factor in determining the spin transport and optical absorption of tungsten disulfide monolayers.
Effect of long-term cultivation on soil organic carbon fractions and metal distribution in humic and fulvic acid in black soil, Northeast China
Authors: Sun C. Y. , Liu J. S. , Wang Y. , Zheng N. , Wu X. Q. , Liu Q.
Published: November 2012

Cultivation affects soil organic matter and its fractions. Fulvic acid (FA) and humic acid (HA) make up an important part of soil organic matter, and their binding capacity influences heavy metal behaviour in soil. This research studied changes in soil organic components and the distribution of copper (Cu), lead (Pb), and zinc (Zn) in HA and FA affected by long-term cultivation in black soils. Uncultivated sites and their adjacent cultivated sites (18, 50, and >200 years) were selected. Alkaline sodium hydroxide/pyrophosphate extraction of humic substances and precipitation of HA by acidification were used to separate the HA and FA fractions. Concentrations of Cu, Pb, and Zn in HA and FA were determined. The content of soil organic carbon (C) had decreased by 30% after 200 years of cultivation. Cultivation led to a moderate decrease (38%) in HA and a minor decrease (7%) in FA. The CHA/CFA ratio, which is a humification parameter, decreased from 2.05 in the uncultivated soil to 1.38 in the soil cultivated for 200 years, indicating a lower degree of humification of organic matter in cultivated soils. Of the Na4P2O7 + NaOH-extracted Pb and Zn, 47–60% and 63–76%, respectively, was associated with FA, showing that FA has a high affinity for Pb and Zn. Of the Na4P2O7 + NaOH-extracted Cu, 55% was in the HA fraction. The share of Cu and Zn in the HA fraction decreased with cultivation time, but cultivation did not bring about a systematic change in Pb distribution in humic substances. The results show that cultivation can decrease the humified C content and metals bound to the HA fraction, and suggest that cultivation may potentially increase the mobility of heavy metals.
Spatial heterogeneity of soil physico-chemical properties in contrasting wetland soils in two agro-ecological zones of Lesotho
Authors: Nkheloane T. , Olaleye A. O. , Mating R.
Published: November 2012

Wetlands are complex ecosystems, often exhibiting considerable spatial variability, making the understanding of soil spatial relationships within them difficult. A study was conducted to evaluate spatial variability of soil physico-chemical properties in two contrasting wetlands in two agro-ecological zones (AEZs) of Lesotho. Soil samples were collected along two transects in mini-pits dug at different depths at 50-m intervals. The collected samples were analysed for particle size, pH, soil organic carbon (SOC), SOC pool, available phosphorus (Av-P), cation exchange capacity (CEC), and base cations. Results showed that within-site variability was very low for sand particles and pH (coefficient of variation <15% for both properties). Soil physical properties generally showed less spatial heterogeneity than chemical properties, which differed widely within and between the study sites. There was generally low correlation between soil properties, and SOC accounted for most of the variation observed at both sites, especially T’sakholo with partial R2 = 94%; at Thaba-Putsoa, partial R2 = 44%. Geostatistical analysis showed that all of the nugget to sill ratios (NSR) showed strong spatial dependence (i.e. NSR of 54–94%) except SOC (T’sakholo stream-bank) with no spatial dependence, with the nugget accounting for 23.43%. We therefore conclude that further wetland studies in Lesotho should attempt to quantify not only the soil properties or processes under investigation but also their spatial variability, because this spatial variability can provide insight into underlying ecosystem processes and may itself indicate wetland condition. In addition, results of stepwise multiple regression showed that SOC and texture could be used across these sites for the sustainable management of these wetlands.
Host epithelial geometry regulates breast cancer cell invasiveness
Authors: Boghaert Eline , Gleghorn Jason P. , Lee KangAe , Gjorevski Nikolce , Radisky Derek C. , Nelson Celeste M.
Published: November 2012

Breast tumor development is regulated in part by cues from the local microenvironment, including interactions with neighboring nontumor cells as well as the ECM. Studies using homogeneous populations of breast cancer cell lines cultured in 3D ECM have shown that increased ECM stiffness stimulates tumor cell invasion. However, at early stages of breast cancer development, malignant cells are surrounded by normal epithelial cells, which have been shown to exert a tumor-suppressive effect on cocultured cancer cells. Here we explored how the biophysical characteristics of the host microenvironment affect the proliferative and invasive tumor phenotype of the earliest stages of tumor development, by using a 3D microfabrication-based approach to engineer ducts composed of normal mammary epithelial cells that contained a single tumor cell. We found that the phenotype of the tumor cell was dictated by its position in the duct: proliferation and invasion were enhanced at the ends and blocked when the tumor cell was located elsewhere within the tissue. Regions of invasion correlated with high endogenous mechanical stress, as shown by finite element modeling and bead displacement experiments, and modulating the contractility of the host epithelium controlled the subsequent invasion of tumor cells. Combining microcomputed tomographic analysis with finite element modeling suggested that predicted regions of high mechanical stress correspond to regions of tumor formation in vivo. This work suggests that the mechanical tone of nontumorigenic host epithelium directs the phenotype of tumor cells and provides additional insight into the instructive role of the mechanical tumor microenvironment.
Anti-inflammatory lipoxin A
4
is an endogenous allosteric enhancer of CB
1
cannabinoid receptor
Authors: Pamplona Fabricio A. , Ferreira Juliano , Menezes de Lima Octávio , Duarte Filipe Silveira , Bento Allisson Freire , Forner Stefânia , Villarinho Jardel G. , Bellocchio Luigi , Wotjak Carsten T. , Lerner Raissa , Monory Krisztina , Lutz Beat , Canetti Claudio , Matias Isabelle , Calixto João Batista , Marsicano Giovanni , Guimarães Marilia Z. P. , Takahashi Reinaldo N.
Published: November 2012

Allosteric modulation of G-protein–coupled receptors represents a key goal of current pharmacology. In particular, endogenous allosteric modulators might represent important targets of interventions aimed at maximizing therapeutic efficacy and reducing side effects of drugs. Here we show that the anti-inflammatory lipid lipoxin A
4
is an endogenous allosteric enhancer of the CB
1
cannabinoid receptor. Lipoxin A
4
was detected in brain tissues, did not compete for the orthosteric binding site of the CB
1
receptor (vs.
3
H-SR141716A), and did not alter endocannabinoid metabolism (as opposed to URB597 and MAFP), but it enhanced affinity of anandamide at the CB1 receptor, thereby potentiating the effects of this endocannabinoid both in vitro and in vivo. In addition, lipoxin A
4
displayed a CB
1
receptor-dependent protective effect against β-amyloid (1–40)-induced spatial memory impairment in mice. The discovery of lipoxins as a class of endogenous allosteric modulators of CB
1
receptors may foster the therapeutic exploitation of the endocannabinoid system, in particular for the treatment of neurodegenerative disorders.
Isotopic evidence for an early shift to C4resources by Pliocene hominins in Chad
Authors: Lee-Thorp Julia , Likius Andossa , Mackaye Hassane T. , Vignaud Patrick , Sponheimer Matt , Brunet Michel
Published: November 2012

Foods derived from C4plants were important in the dietary ecology of early Pleistocene hominins in southern and eastern Africa, but the origins and geographic variability of this relationship remain unknown. Carbon isotope data show thatAustralopithecus bahrelghazaliindividuals from Koro Toro in Chad are significantly enriched in13C, indicating a dependence on C4resources. As these sites are over 3 million years in age, the results extend the pattern of C4dependence seen inParanthropus boiseiin East Africa by more than 1.5 million years. The Koro Toro hominin fossils were found in argillaceous sandstone levels along with abundant grazing and aquatic faunal elements that, in combination, indicate the presence of open to wooded grasslands and stream channels associated with a greatly enlarged Lake Chad. In such an environment, the most abundant C4plant resources available toA. bahrelghazaliwere grasses and sedges, neither of which is usually considered as standard great ape fare. The results suggest an early and fundamental shift in hominin dietary ecology that facilitated the exploitation of new habitats.
Implantable microenvironments to attract hematopoietic stem/cancer cells
Authors: Lee Jungwoo , Li Matthew , Milwid Jack , Dunham Joshua , Vinegoni Claudio , Gorbatov Rostic , Iwamoto Yoshiko , Wang Fangjing , Shen Keyue , Hatfield Kimberley , Enger Marianne , Shafiee Sahba , McCormack Emmet , Ebert Benjamin L. , Weissleder Ralph , Yarmush Martin L. , Parekkadan Biju
Published: November 2012

The environments that harbor hematopoietic stem and progenitor cells are critical to explore for a better understanding of hematopoiesis during health and disease. These compartments often are inaccessible for controlled and rapid experimentation, thus limiting studies to the evaluation of conventional cell culture and transgenic animal models. Here we describe the manufacture and image-guided monitoring of an engineered microenvironment with user-defined properties that recruits hematopoietic progenitors into the implant. Using intravital imaging and fluorescence molecular tomography, we show in real time that the cell homing and retention process is efficient and durable for short- and long-term engraftment studies. Our results indicate that bone marrow stromal cells, precoated on the implant, accelerate the formation of new sinusoidal blood vessels with vascular integrity at the microcapillary level that enhances the recruitment hematopoietic progenitor cells to the site. This implantable construct can serve as a tool enabling the study of hematopoiesis.
FoxO is a critical regulator of stem cell maintenance in immortal
Hydra
Authors: Boehm Anna-Marei , Khalturin Konstantin , Anton-Erxleben Friederike , Hemmrich Georg , Klostermeier Ulrich C. , Lopez-Quintero Javier A. , Oberg Hans-Heinrich , Puchert Malte , Rosenstiel Philip , Wittlieb Jörg , Bosch Thomas C. G.
Published: November 2012

Hydra
’s unlimited life span has long attracted attention from natural scientists. The reason for that phenomenon is the indefinite self-renewal capacity of its stem cells. The underlying molecular mechanisms have yet to be explored. Here, by comparing the transcriptomes of
Hydra
’s stem cells followed by functional analysis using transgenic polyps, we identified the transcription factor forkhead box O (FoxO) as one of the critical drivers of this continuous self-renewal.
foxO
overexpression increased interstitial stem cell and progenitor cell proliferation and activated stem cell genes in terminally differentiated somatic cells.
foxO
down-regulation led to an increase in the number of terminally differentiated cells, resulting in a drastically reduced population growth rate. In addition, it caused down-regulation of stem cell genes and antimicrobial peptide (AMP) expression. These findings contribute to a molecular understanding of
Hydra
’s immortality, indicate an evolutionarily conserved role of FoxO in controlling longevity from
Hydra
to humans, and have implications for understanding cellular aging.