bluuebunny/crossref_metadata_2025 huggingface dataset:
Endophytic Fungi from Dragon's Blood Specimens: Isolation, Identification, Phylogenetic Diversity and Bioactivity
Authors: Cui Jin‐long , Guo Shun‐xing , Dong Hailing , Xiao Peigen
Published: February 2011

Endophytic fungi from Dragon's blood specimens of different locations of China were characterized taxonomically and investigated concerning their antimicrobial and antitumor activity against six pathogenic microbes and five tumor cells. A total of 49 endophytic fungi were obtained from Dragon's blood materials of Dracaena spp., 18 taxa were represented by 43 (87.8%) isolates and only six (12.2%) isolates were unknown. Twenty (40.8%) of the isolates displayed antimicrobial activity against at least one pathogenic microorganism. Three isolates YNDC07, BJDC06 and BJDC09 displayed significant antimicrobial activities against Staphylococcus aureus, Cryptococcus neoformans and Aspergillus fumigates, respectively. The results of antitumor activity by the MTT assay revealed that 26.5%, 69.4%, 48.9%, 6.1% and 42.9% of isolate fermentation broths displayed growth inhibition on HepG2 cells, SKVO3 cells, MCF7 cells, HL‐60 cells and 293‐T cells, respectively. HNDC09 and HNDC10 showed very strong antitumor activity against MCF7 and 293‐T, respectively. The results showed that endophytic fungi in Dragon's blood samples were valuable in screening antitumor and antimicrobial bioactivity agents. Copyright © 2011 John Wiley & Sons, Ltd.
Protective Effects of Methoxyflavone Derivatives from Black Galingale against Glutamate Induced Neurotoxicity in Primary Cultured Rat Cortical Cells
Authors: Moon Hyung‐In , Cho Sang‐Buem , Lee Jai‐Heon , Lee Young‐Choon , Lee Jun‐Hyeong , Lee Chi‐Ho , Kim Soo‐Ki
Published: February 2011

To examine the neuroprotective effects of black galingale, its protection was tested against glutamate‐induced neurotoxicity in primary cortical cultured neurons. It was found that an aqueous extract of this medicinal plant exhibited significant protection against glutamate‐induced toxicity in primary cultured rat cortical cells. In order to clarify the neuroprotective mechanism(s) of this observed effect, isolation was performed to seek and identify active fractions and components. By such fractionation, bioactive methoxyflavone derivatives were isolated from the methanol extracts from the air‐dried rhizomes of black galingale. 5‐Hydroxy‐3,7,3′,4′‐tetramethoxyflavone exhibited significant neuroprotective activities against glutamate‐induced toxicity, exhibiting cell viability of about 60–70%, at concentrations ranging from 0.1 μm to 10 μm. Therefore, the neuroprotective effect of black galingale might be due to the inhibition of glutamate‐induced toxicity by the methoxyflavone derivatives it contains. Copyright © 2011 John Wiley & Sons, Ltd.
A computational study on the ring stretching modes of halogen‐substituted pyridine involved in H‐bonding
Authors: Cao Li Juan , Li An Yong , Xu Li , Zhang Ying
Published: February 2011

Density functional method B3LYP plus the AUG‐cc‐pVDZ and AUG‐cc‐pVTZ basis sets is used to investigate ring normal modes of halogen‐substituted pyridines involved in the N···HX H‐bonds with HX (X = F, Cl). The results demonstrated that the formation of hydrogen bond leads to an increase in the frequencies of the ring breathing modev1, the N‐para‐C stretching modev6aand the meta‐CC stretching modev8a, whereas there is no change in the triangle modev12for free pyridine and a smaller blue shift for substituted pyridines. There is a strong coupling between the CY stretching vibration and the triangle mode (ortho‐ and para‐substituted) or the breathing mode (meta‐substituted) in substituted pyridines, which leads to the frequency decrease in the triangle or breathing modes. The natural bond orbital analysis suggests that electrostatic interaction and charge transfer caused by the intermolecular and intramolecular hyperconjugations are the origin of the frequency blue shift in the ring stretching modes. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
Generating SysML views from an OPM model: Design and evaluation
Authors: Grobshtein Yariv , Dori Dov
Published: February 2011

Conceptual modeling is key to Model‐Based Systems Engineering (MBSE) approaches. OPM (Object‐Process Methodology) and SysML (OMG Systems Modeling Language) are two state‐of‐the‐art conceptual modeling languages. While both languages aim at the same purpose of providing a means for general‐purpose systems engineering, these languages take different approaches in realizing this goal. As each of the languages has its relative strengths and weaknesses, ways to create synergies between them are considered in this work. We propose combining advantages of each language through automatic generation of several SysML views from an OPM model. To this end, we developed a new algorithm and software application for implementing the OPM‐to‐SysML views generation, and evaluated the results through an experiment conducted for this purpose. The formally constructed experiment described in this paper, which has been designed to test the quality of the auto‐generated diagrams and their impact on system comprehension, indicates that the addition of some auto‐generated SysML views to an OPM system model has increased system comprehension level. Our approach can benefit various stakeholders by promoting better system understanding, standardization, and improved interoperability. © 2011 Wiley Periodicals, Inc. Syst Eng 14:
A new systems engineering approach for a Socio‐Critical System: A case study of claims‐payment failures of Japan's insurance industry
Authors: Yasui Toshiyuki
Published: February 2011

Since the 1950s there have been numerous contributions proposing solutions to failures of social systems. However, we have hardly found a holistic and interdisciplinary approach to a failed social system beyond “stove‐piped” academic disciplines. This paper identifies a new holistic and interdisciplinary systems engineering methodology of systems engineering for a social system through a case study of Japan's insurance industry. The new methodology is a “soft” systems‐approach to accommodate goals of stakeholders in a failed social system. First, the three elements of a social system are identified. Second, the multiple viewpoint model transforms these three elements of the human activity view to a new set of elements of the Holon view. Third, a social system of the Holon view is redefined as a Socio‐Critical System (SCS). Finally, the Vee Model is applied for fixing a problem in the SCS. From 2005 to 2008, massive claims‐payment failures cases were found in Japan's private insurance companies. They became big social scandals. The insurance claims‐payment system is a typical SCS. The Financial Services Agency (FSA), Japan's financial services supervision authority, identified, with the “unintended” systems approach, dysfunctions of the insurance claims‐payment system. This FSA action, even though the authority was not aware of the effectiveness of the methodology, proved to be positive in applying the Vee Model for solving failures in those claims‐payment systems. © 2011 Wiley Periodicals, Inc.
Lipid‐sensing nuclear receptors in the pathophysiology and treatment of the metabolic syndrome
Authors: Vacca Michele , Degirolamo Chiara , Mariani‐Costantini Renato , Palasciano Giuseppe , Moschetta Antonio
Published: February 2011

Metabolic syndrome (MS) is a cluster of different diseases, namely central obesity, hypertension, hyperglycemia, and dyslipidemia, together with a pro‐thrombotic and pro‐inflammatory state. These metabolic abnormalities are often associated with an increased risk for cardiovascular disease (CVD) and cancer. Dietary and lifestyle modifications are currently believed more effective than pharmacological therapies in the management of MS patients. Nevertheless, the relatively low grade of compliance of patients to these recommendations, as well as the failure of current therapies, highlights the need for the discovery of new pharmacological and nutraceutic approaches. A deeper knowledge of the patho‐physiological events that initiate and support the MS is mandatory. Lipid‐sensing nuclear receptors (NRs) are the master transcriptional regulators of lipid and carbohydrate metabolism and inflammatory responses, thus standing as suitable targets. This review focuses on the physiological relevance of the NRs (peroxisome proliferator‐activated receptors, liver X receptors, and farnesoid X receptor) in the control of whole‐body homeostasis, with a special emphasis on lipid and glucose metabolism, and on the relationships between metabolic unbalances, systemic inflammation, and the onset of CVD. Future perspectives and possible clinical applications are also presented. WIREs Syst Biol Med 2011 3 562–587 DOI: 10.1002/wsbm.137

This article is categorized under:

Biological Mechanisms > Cell Signaling
The Leverage of Demographic Dynamics on Carbon Dioxide Emissions: Does Age Structure Matter?
Authors: Zagheni Emilio
Published: February 2011

This article provides a methodological contribution to the study of the effect of changes in population age structure on carbon dioxide (CO2) emissions. First, I propose a generalization of the IPAT equation to a multisector economy with an age-structured population and discuss the insights that can be obtained in the context of stable population theory. Second, I suggest a statistical model of household consumption as a function of household size and age structure to quantitatively evaluate the extent of economies of scale in consumption of energy-intensive goods, and to estimate age-specific profiles of consumption of energy-intensive goods and of CO2 emissions. Third, I offer an illustration of the methodologies using data for the United States. The analysis shows that per-capita CO2 emissions increase with age until the individual is in his or her 60s, and then emissions tend to decrease. Holding everything else constant, the expected change in U.S. population age distribution during the next four decades is likely to have a small, but noticeable, positive impact on CO2 emissions.
Development of repetitive behavior in a mouse model: Roles of indirect and striosomal basal ganglia pathways
Authors: Tanimura Yoko , King Michael A. , Williams Dustin K. , Lewis Mark H.
Published: February 2011

Restricted repetitive behaviors (stereotypy, compulsions, rituals) are diagnostic for autism spectrum disorder and common in related neurodevelopmental disorders. Despite their prevalence in clinical populations, underlying mechanisms associated with the development of these behaviors remain poorly understood. We examined the role of the indirect basal ganglia pathway in the development of stereotypy using deer mice. We measured neuronal metabolic activity in the subthalamic nucleus (STN) and other relevant brain regions using cytochrome oxidase (CO) histochemistry at three developmental time‐points. Although no differences were observed in STN across development, significant differences were found when mice were grouped by developmental trajectory. At 6 weeks post‐weaning, significantly lower CO activity in STN was found in those trajectory groups that developed high levels of repetitive behavior versus the trajectory group that did not, suggesting the development of stereotypy is associated with decreased indirect basal ganglia pathway activity. In addition, we tested the hypothesis that preferential activation of striatal striosomes relative to surrounding matrix would be associated with the development of stereotypy. No differences in the relative activation of these striatal compartments were observed across development or among trajectory groups. Our results point to dynamic changes in the indirect pathway associated with the development of repetitive behavior and extends our prior work linking reduced indirect pathway activation to stereotypy in adult deer mice.
Effect of feeding tuna oil or soyabean oil as supplements to sows in late pregnancy on piglet tissue composition and viability
Authors: Rooke J. A. , Bland I. M. , Edwards S. A.
Published: February 2011

To investigate whether long-chain n-3 polyunsaturated fatty acids could cross the porcine placenta in late pregnancy and alter neonatal piglet tissue composition, multiparous sows (seven per diet) were fed on diets containing a supplement (30 g/kg) of either soyabean oil or tuna oil for the last 21 d of pregnancy and the first 7 d of lactation. The proportions of all fatty acids, except 18:1n-7, differed between diets: in particular, the tuna-oil-containing diet supplied more 22:6n-3 and less 18:2n-6 fatty acids than the soyabean-oil-containing diet. The proportions of n-3 fatty acids, particularly 22:6n-3 (g/100 g total fatty acids) in sow plasma, colostrum and milk were increased and the proportion of 18:2n-6 was decreased by feeding tuna oil. Piglet tissue n-3 fatty acid proportions (particularly 22:6n-3), obtained shortly after birth, were increased in piglets born to tuna-oil-fed sows compared with progeny of soyabean-oil-fed sows. The increase in the proportion of n-3 fatty acids (g/100 g total fatty acids) in piglet tissues as a result of tuna-oil feeding, compared with soyabean-oil-feeding, was in the order plasma>liver>erythrocytes>spleen>brain>retina. Piglets born to tuna-oil-fed sows had a lower viability score at birth than the progeny of soyabean-oil-fed sows. The proportions of long-chain n-3 fatty acid in tissues of new-born piglets were increased by feeding tuna oil to the sow in late pregnancy; however no improvements in piglet viability were observed.
Lagrangian blocking in highly viscous shear flows past a sphere
Authors: CAMASSA ROBERTO , McLAUGHLIN RICHARD M. , ZHAO LONGHUA
Published: February 2011

An analytical and computational study of Lagrangian trajectories for linear shear flow past a sphere or spheroid at low Reynolds numbers is presented. Using the exact solutions available for the fluid flow in this geometry, we discover and analyse blocking phenomena, local bifurcation structures and their influence on dynamical effects arising in the fluid particle paths. In particular, building on the work by Chwang & Wu, who established an intriguing blocking phenomenon in two-dimensional flows, whereby a cylinder placed in a linear shear prevents an unbounded region of upstream fluid from passing the body, we show that a similar blocking exists in three-dimensional flows. For the special case when the sphere is centred on the zero-velocity plane of the background shear, the separatrix streamline surfaces which bound the blocked region are computable in closed form by quadrature. This allows estimation of the cross-sectional area of the blocked flow showing how the area transitions from finite to infinite values, depending on the cross-section location relative to the body. When the sphere is off-centre, the quadrature appears to be unavailable due to the broken up-down mirror symmetry. In this case, computations provide evidence for the persistence of the blocking region. Furthermore, we document a complex bifurcation structure in the particle trajectories as the sphere centre is moved from the zero-velocity plane of the background flow. We compute analytically the emergence of different fixed points in the flow and characterize the global streamline topology associated with these fixed points, which includes the emergence of a three-dimensional bounded eddy. Similar results for the case of spheroids are considered in Appendix B. Additionally, the broken symmetry offered by a tilted spheroid geometry induces new three-dimensional effects on streamline deflection, which can be viewed as effective positive or negative suction in the horizontal direction orthogonal to the background flow, depending on the tilt orientation. We conclude this study with results on the case of a sphere embedded at a generic position in a rotating background flow, with its own prescribed rotation including fixed and freely rotating. Exact closed-form solutions for fluid particle trajectories are derived.
Poiseuille and thermal transpiration flows of a highly rarefied gas: over-concentration in the velocity distribution function
Authors: TAKATA SHIGERU , FUNAGANE HITOSHI
Published: February 2011

Poiseuille and thermal transpiration flows of a highly rarefied gas are investigated on the basis of the linearized Boltzmann equation, with a special interest in the over-concentration of molecules on velocities parallel to the walls. An iterative approximation procedure with an explicit error estimate is presented, by which the structure of the over-concentration is clarified. A numerical computation on the basis of the procedure is performed for a hard-sphere molecular gas to construct a database that promptly gives the induced net mass flow for an arbitrary value of large Knudsen numbers. An asymptotic formula of the net mass flow is also presented for molecular models belonging to Grad's hard potential. Finally, the resemblance of the profiles between the heat flow of the Poiseuille flow and the flow velocity of the thermal transpiration is pointed out. The reason is also given.
Spatial Translation and ‘Present-ness’ in Site-Specific Dance Performance
Authors: Hunter Victoria
Published: February 2011

In this article Victoria Hunter considers notions of spatial translation, ‘present-ness’, and ‘embodied reflexivity’ within site-specific dance performance. Through a discussion of the author's site-specific dance installation entitled Project 3, she explores choreographic processes that aimed to facilitate, transform, and heighten the lived experience of site by the performer and the audience through phenomenologically informed movement inquiry. Forming part of the author's practice-led PhD investigation into the relationship between the site and the creative process, the performance was the third in a trilogy of site-specific works exploring the potential for site-specific dance performance to ‘reveal’ the site through movement, challenging both performers and audience members to engage with new ways of experiencing the site-world. Victoria Hunter is a practitioner-researcher and lecturer in dance at the University of Leeds. Her research is practice-led and is concerned with the nature of dance-making processes within site-specific choreography. She completed her PhD in site-specific dance performance in December 2009.
On Double Edge Theatre
Authors: Klein Stacy
Published: February 2011

Founded in Boston by Stacy Klein in 1982, initially as a women's theatre, Double Edge moved to Ashfield in Massachusetts in 1997 to the rural complex now known as the Farm Center. The Farm comprises rehearsal rooms, living quarters, technical workshops, an ante-room to welcome and dine spectators, a magnificent loft-like performance space, and acres of land with trees and a pond. The whole is set against a soft New England landscape, and the Farm's grounds are the almost idyllic environment for the summer promenade spectacles that, like its more formal productions indoors, provide a focus for locals, sustaining their sense of community and even the myth of community nurtured historically in these parts. In this conversation of 13 and 14 November 2009 (which was extended in August 2010 after The Firebird, the summer spectacle of that year), Stacy Klein discusses how local people support Double Edge and otherwise form a long-term relationship with the company, now visited by spectators as well as practitioners from further afield – Klein's Polish teachers and mentors among them. Double Edge is a devising company, working with improvisation and free association to form strong visual imagery through pronounced physical movement, which also involves circus skills. This, together with a frequently startling use of objects, is the basis of their magical realism (notably in the unPOSSESSED of 2004, after Don Quixote), a style developed by the company in its rural retreat, and subsequently combined with the tonalities of grotesque surrealism. The Republic of Dreams, for instance, inspired by the life and work of Bruno Schulz, enters the world of vivid dreams, powerful memories, and nostalgic echoes, the whole evoking an evanescent past into which its agile, versatile performers – some singing, some dancing – tune in, like ghosts absent and present in one and the same instance. The two productions noted here are part of what Klein calls a ‘Cycle’ – a grouping of works that have evolved over a number of years as separate pieces, some beginning life as a summer show before they grow and link with the other pieces of a given Cycle, which is almost always a trilogy. Gradual, consistent development is key to the company's work, as is its belief in a distinct company ethos, which its trainees are invited to share. Maria Shevtsova, who enjoyed the Farm's hospitality when she talked with Stacy Klein, holds the Chair in Drama and Theatre Arts at Goldsmiths, University of London, and is the co-editor of New Theatre Quarterly.
Strength in Depth in Romania
Authors: Herbert Ian
Published: February 2011

Report on the twentieth Romanian National Theatre Festival, held in Bucharest from 30 October to 7 November 2010.
Meridional shifts in the marine ITCZ and the tropical hydrologic cycle over the last three glacial cycles
Authors: Schmidt Matthew W. , Spero Howard J.
Published: February 2011

Paleoproxy studies show a strong correlation between tropical climate and high‐latitude temperature variability recorded in the Greenland ice cores over the last glacial cycle. In particular, abrupt cooling events in the Greenland Ice Sheet Project II δ18O ice record appear synchronous with a southward migration of the Intertropical Convergence Zone (ITCZ) in the Atlantic, a weakening of the Indian and East Asian monsoon systems, and a strengthening of the South American monsoon system. Because this high‐to‐low‐latitude climate teleconnection significantly alters the tropical hydrologic cycle around the globe, it plays a critical role in regulating global climate on glacial‐interglacial time scales. We compare δ18Oseawater reconstructions (a salinity proxy generated from previously published Mg/Ca and oxygen isotope data on Globigerinoides ruber (white var.)) obtained from western Caribbean core ODP 999A and western equatorial Pacific core 806B across the last three glacial cycles to show that systematic variations in surface salinity at these sites suggest the tropical Hadley cell hydrologic system undergoes systematic reorganizations that differ dramatically between warm interglacial and cold glacial periods. Furthermore, cross‐spectral and phase angle analyses of the ice‐volume‐corrected Caribbean and western Pacific δ18OSW records reveal a 100 kyr frequency in both records that is almost 180° out of phase and a 23 kyr frequency that is nearly in phase. This results in the development of a very large δ18OSW gradient between the Caribbean and the western equatorial Pacific on glacial‐interglacial time scales that is best explained by a southward shift in both the Atlantic and Pacific ITCZ during North Atlantic cold phases.
Middle Eocene paleomagnetic data from the eastern Sakarya Zone and the central Pontides: Implications for the tectonic evolution of north central Anatolia
Authors: Çinku Mualla Cengiz , Hisarlı Z. Mümtaz , Heller Friedrich , Orbay Naci , Ustaömer Timur
Published: February 2011

A paleomagnetic investigation has been carried out on Middle Eocene volcanic rocks at 23 sites in the eastern Sakarya Zone and the central Pontides of north central Anatolia in order to better understand the regional tectonic evolution of the main zones of northeastern Anatolia in the Middle Eocene. The results constrain the tectonic evolution of the area when evaluated in conjunction with earlier published paleomagnetic directions from 92 localities. Small counterclockwise rotations in the range of R ± ΔR = −1.3 ± 1.4° to R ± ΔR = −17.2 ± 16.8°, with respect to Eurasia, are observed in the central Pontides on the northern side of the North Anatolian Fault (NAF). Clockwise rotations ranging between R ± ΔR = 8.5 ± 15.1° and R ± ΔR = 29.7 ± 12.0° are observed between the NAF and the Sungurlu Fault (SF), in the eastern Sakarya zone. Counterclockwise rotations of R ± ΔR = −18.9 ± 12.4° to R ± ΔR = −42.2 ± 6.9° are observed to the south of the SF. Our findings, combined with previous data, support the indentation model of Kaymakcı et al. (2000, 2003a, 2003b), which postulates the collision and northeast directed indentation of the Kırşehir Block into the Sakarya Zone. This model, which was developed to explain the evolution of the Çankırı Basin, can also explain the variable magnitudes of paleomagnetically determined rotations, thrust directions, and the curvature of the North Anatolian ophiolite belt.
On the interaction between bathymetry and climate in the system dynamics and preferred levels of the Great Salt Lake
Authors: Mohammed Ibrahim Nourein , Tarboton David G.
Published: February 2011

The Great Salt Lake is a terminal lake whose level is determined by the balance between inflows and outflows. We examine the causes for multimodality in the distributions of lake level and hence volume and area that have previously been examined from a system dynamics perspective. We focus on the role of bathymetry in the dynamics of this system and show that some of the modes that are observed and that represent preferred system states are attributable to features of the bathymetry described using the topographic area‐volume relationship. Being a terminal lake, the only “outflow” is evaporation, which depends directly on lake area, which adjusts (with stochastic fluctuations) to balance inflows. Where the topographic side slopes are relatively flat and the lake goes through a large change in area for a given increase in level, the outflux evaporation will go through a corresponding large change, tending to stabilize the lake at that point. Conversely, where topographic side slopes are relatively steep, the stabilizing effect is diminished. This effect was quantified using the derivative of the lake area–lake volume function determined from U.S. Geological Survey topographic and bathymetric surveys. We show how some of the observed modes that represent preferred lake volume states are attributable to peaks in this area‐volume derivative, while a complete description of the observed distribution of lake volume requires combining the bathymetry represented by the area‐volume derivative with a multimodal lake area distribution that may be connected to multimodality in the aggregate hydrological forcing.
Functional model of water balance variability at the catchment scale: 1. Evidence of hydrologic similarity and space‐time symmetry
Authors: Sivapalan Murugesu , Yaeger Mary A. , Harman Ciaran J. , Xu Xiangyu , Troch Peter A.
Published: February 2011

This paper presents analysis of annual water balance variability, (1) regional (between‐catchment) variability and (2) between‐year (interannual) variability and the symmetry between the two. This involved analysis of the annual water balance in terms of a two‐stage partitioning, first, of annual precipitation into quick flow and soil wetting and, subsequently, of the resulting soil wetting into slow flow and vaporization. The nature of this water balance partitioning is explored by completing the above analysis in 377 Model Parameter Estimation Experiment (MOPEX) catchments located across the continental United States. We fitted analytical functional relationships to the partitioning at each stage, producing expressions for the three components of quick flow, slow flow, and vaporization. They indicate that the heterogeneity of water balance partitioning among the MOPEX catchments is underlain by a universal relationship that is transferable regionally. Key nondimensional similarity parameters are identified that serve to connect this invariant regional relationship to site‐specific response characteristics. These nondimensional formulations are extended to derive analytical expressions for several common metrics of annual water balance. The ability of the functional theory to predict regional patterns of mean annual water balance and interannual variability in individual catchments is assessed. Our analyses show a close symmetry between spatial (regional) variability of mean annual water balances and general trends of temporal (interannual) variability. The suggested functional theory can thus be the basis for data‐based assessments of hydrologic similarity and used to assist with predictions of the effects of long‐term climate variability and change, through providing a theoretical framework for “space for time” substitutions.
The dissociative adsorption of hydrogen on Pt(111): Actuation and acceleration by atomic defects
Authors: Poelsema Bene , Lenz Klaus , Comsa George
Published: February 2011

The dissociation of hydrogen at atomic surface defects is the strongly dominant, if not the decisive, step in the chain of events eventually leading to chemisorbed H-atoms on Pt(111). This holds for perpendicular kinetic energies of the gas phase molecules from 8 to 60 meV, i.e., covering the range relevant to hydrogenation reactions. This insight has been gained in the present study in which we reversibly varied the defect density on one and the same crystal in a controlled way. Information has been derived from measuring the adsorption kinetics as a function of coverage. Two distinct adsorption channels are distinguished. The first, indirect one, prevails at lower H-coverage and involves capture into a non-accommodated molecular precursor state followed by dissociation at step sites as described in our recent paper. The second one, dominant at higher coverage and non-negligible defect densities, obeys second order Langmuir kinetics. Here the dissociative adsorption takes place directly at step sites with a cross section of 0.24 unit cells (initial sticking probability 24% of the step density). These results are consistent with thermally programmed desorption data: the direct channel is responsible for the emergence of the low temperature peak in thermal desorption spectroscopy, usually denoted with β1, while the indirect channel is represented by the β2 state. The dependence on the perpendicular component of the hydrogen kinetic energy is distinctly different for the two channels: the indirect one shows power law behavior with an exponent 1.9 ± 0.1, while the direct one shows no perpendicular energy dependence at all.
Improved low concentration gas detection system based on intracavity fiber laser
Authors: Zhang Hongxia , Liu Kun , Jia Dagong , Xu Tianhua , Liu Tiegen , Peng Gangding , Jing Wencai , Zhang Yimo
Published: February 2011

The improvement of a low concentration gas detection system based on the intracavity fiber laser is proposed in this paper. The sensitivity of the system is deduced based on Lambert–Beer law. The optimized system was established with the gas cell made elaborately. In order to apply the wavelength sweeping technique, the fiber Bragg grating reflector was substituted by the wavelength independent Faraday rotation reflector. The sensitivity of the system for acetylene detection is reduced to less than 100 ppm by using the average of three absorption spectra. The acetylene detection coefficients of variation with different concentrations are measured. The gas measurement system is validated to detect low concentration gas effectively.
A diagnostic system for electrical faults in a high current discharge plasma setup
Authors: Nigam S. , Aneesh K. , Navathe C. P. , Gupta P. D.
Published: February 2011

A diagnostic system to detect electrical faults inside a coaxial high current discharge device is presented here. This technique utilizes two biconical antennas picking up electromagnetic radiation from the discharge device, a voltage divider sensing input voltage, and a Rogowski coil measuring the main discharge current. A computer program then analyses frequency components in these signals and provides information as to whether the discharge event was normal or any breakdown fault occurred inside the coaxial device. The diagnostic system is developed for a 450 kV and 50 kA capillary discharge plasma setup. For the setup various possible faults are analyzed by electrical simulation, followed by experimental results. In the case of normal discharge through the capillary load the dominant frequency is ∼4 MHz. Under faulty conditions, the peak in magnitude versus frequency plot of the antenna signal changes according to the fault position which involves different paths causing variation in the equivalent circuit elements.
Rapid consolidation of powdered materials by induction hot pressing
Authors: LaLonde Aaron D. , Ikeda Teruyuki , Snyder G. Jeffrey
Published: February 2011

A rapid hot press system in which the heat is supplied by RF induction to rapidly consolidate thermoelectric materials is described. Use of RF induction heating enables rapid heating and consolidation of powdered materials over a wide temperature range. Such rapid consolidation in nanomaterials is typically performed by spark plasma sintering (SPS) which can be much more expensive. Details of the system design, instrumentation, and performance using a thermoelectric material as an example are reported. The Seebeck coefficient, electrical resistivity, and thermal diffusivity of thermoelectric PbTe material pressed at an optimized temperature and time in this system are shown to agree with material consolidated under typical consolidation parameters.
Note: Human heartbeat measurement on the basis of current generated by electrostatic induction
Authors: Kurita Koichi
Published: February 2011

In this study, we developed an effective nonattached, noncontact technique for measurement of the human heartbeat. This method detects the human heartbeat by measuring the current generated by variations in the capacitance between a given electrode and the human body. An electrode is placed a few centimeters from the subject's chest, and the electrostatic induction current (on the order of picoamperes) flowing through the electrode is then detected. We propose an occurrence model for the electrostatic induction current generated by variations in the electrostatic capacitance generated because of the human heartbeat, with respect to a given measurement electrode. Furthermore, we compared waveforms of the human heartbeat simultaneously obtained by using conventional electrocardiography (ECG) and our proposed electrostatic induction method. The waveform obtained using the proposed method had the same cycle as that obtained using conventional ECG. This confirms that we can detect the human heartbeat under nonattached, noncontact conditions.
A novel facility for ageing materials with narrow-band ultraviolet radiation exposure
Authors: Kärhä Petri , Heikkilä Anu , Ruokolainen Kimmo , Kaunismaa Merja
Published: February 2011

A facility for exploring wavelength dependencies in ultraviolet (UV) radiation induced degradation in materials has been designed and constructed. The device is essentially a spectrograph separating light from a lamp to spectrally resolved UV radiation. It is based on a 1 kW xenon lamp and a flat-field concave holographic grating 10 cm in diameter. Radiation at the wavelength range 250–500 nm is dispersed onto the sample plane of 1.5 cm in height and 21 cm in width. The optical performance of the device has been characterized by radiometric measurements. Using the facility, test samples prepared of regular newspaper have been irradiated from 1 to 8 h. Color changes on the different locations of the aged samples have been quantified by color measurements. Yellowness indices computed from the color measurements demonstrate the capability of the facility in revealing wavelength dependencies of the material property changes in reasonable time frames.
On the origin of time-temperature superposition in disordered solids
Authors: Sakellis I.
Published: February 2011

In this paper by employing various experimental facts for different classes of materials, two critical conditions are derived, which lead to the empirically used scaling relations describing the ac response of disordered nonmetals. In parallel the origin of time-temperature superposition is explored while the scenario of time-pressure (or /temperature) superposition is introduced. Moreover, a unified equation for the entire frequency range of ac conductivity is proposed. The results are physically visualized within the frame of percolation theory, attempting to establish a link to the dominant approaches of Hunt [Philos. Mag. B 81, 875 (2001)] and Dyre [J. Appl. Phys. 64, 2456 (1988)].
Scaling analysis of submicrometer nickel-oxide-based resistive switching memory devices
Authors: Ielmini D. , Spiga S. , Nardi F. , Cagli C. , Lamperti A. , Cianci E. , Fanciulli M.
Published: February 2011

Resistive switching memory (RRAM) based on the redox-induced conductivity change in some metal oxides attracts considerable interest as a new technology for next-generation nonvolatile electronic storage. Although resistance-switching phenomena in several transition metal oxides have been known from decades, the details of the switching mechanisms and the nature of the different resistive states are still largely debated. For nonvolatile memory applications, the scaling potential of RRAMs is the most relevant issue, and understanding the scaling capability of RRAM devices requires a sound interpretation of resistance-switching operation and reliability aspects. This work addresses the scaling dependence of RRAM switching parameters. The dependence on the electrode area and on the size of the conductive filament (CF) responsible for low-resistance memory state is investigated. The RRAM conduction modes depending on CF size are discussed based on temperature dependent resistance analysis. Reset characteristics in different resistance states are explained by a Joule heating model for CF oxidation.
The Twente turbulent Taylor–Couette (T3C) facility: Strongly turbulent (multiphase) flow between two independently rotating cylinders
Authors: van Gils Dennis P. M. , Bruggert Gert-Wim , Lathrop Daniel P. , Sun Chao , Lohse Detlef
Published: February 2011

A new turbulent Taylor–Couette system consisting of two independently rotating cylinders has been constructed. The gap between the cylinders has a height of 0.927 m, an inner radius of 0.200 m, and a variable outer radius (from 0.279 to 0.220 m). The maximum angular rotation rates of the inner and outer cylinder are 20 and 10 Hz, respectively, resulting in Reynolds numbers up to 3.4 × 106 with water as working fluid. With this Taylor–Couette system, the parameter space (Rei, Reo, η) extends to (2.0 × 106, ±1.4 × 106, 0.716−0.909). The system is equipped with bubble injectors, temperature control, skin-friction drag sensors, and several local sensors for studying turbulent single-phase and two-phase flows. Inner cylinder load cells detect skin-friction drag via torque measurements. The clear acrylic outer cylinder allows the dynamics of the liquid flow and the dispersed phase (bubbles, particles, fibers, etc.) inside the gap to be investigated with specialized local sensors and nonintrusive optical imaging techniques. The system allows study of both Taylor–Couette flow in a high-Reynolds-number regime, and the mechanisms behind skin-friction drag alterations due to bubble injection, polymer injection, and surface hydrophobicity and roughness.
Spatial hole burning in high-power edge-emitting lasers: A simple analytical model and the effect on laser performance
Authors: Ryvkin B. S. , Avrutin E. A.
Published: February 2011

A simple analytical model for the longitudinal distributions of photon and carrier densities in edge-emitting semiconductor lasers significantly above threshold is presented. It is shown that under the conditions considered, the shape of these distributions does not depend on pumping current. Good agreement with previous numerical and seminumerical investigations is obtained. It is shown that any direct effect of longitudinal spatial hole burning on the output power is seen only at very low output mirror reflectances and even then is weak, implying that the main effects of longitudinal nonuniformity are indirect ones, through carrier leakage.
Stimulated emission in the red, green, and blue in a nanostructured glass ceramics
Authors: Lahoz F. , Capuj N. , Haro-González P. , Martín I. R. , Pérez-Rodríguez C. , Cáceres J. M.
Published: February 2011

Red, green, and blue stimulated emissions have been achieved in Ho3+ doped oxyfluoride glass ceramic at room temperature. The material shows three emission bands at the red (650 nm), green (545 nm), and blue (488 nm) regions under infrared excitation at 750 nm. These emission bands are caused by a photon avalanche upconversion process previously reported. A pump and probe experimental setup has been designed to show stimulated emissions at the three bands. The pump power threshold for positive gain in the 490 nm band has been estimated around 2.7 kW/cm2. Higher thresholds are expected for the other bands.
Self-organization of two-dimensional SiGe nanodot arrays using selective etching of pure-edge dislocation network
Authors: Nakamura Yoshiaki , Takahashi Masahiko , Fujiwara Tatsuki , Kikkawa Jun , Sakai Akira , Nakatsuka Osamu , Zaima Shigeaki
Published: February 2011

A self-organization technique of two-dimensional SiGe nanodot arrays was developed using selective etching of SiGe/Si substrates that have a pure-edge dislocation network at the interface. The pure-edge dislocation network was selectively etched by a water solution of CrO3 and HF. This produced SiGe nanodot arrays with nanometer-scale periodicities. The periodicities and the compositions of the SiGe nanodot arrays correspond with that of the interfacial pure-edge dislocation network and that at the interface, respectively, in the SiGe/Si substrates prior to etching. We found that the etchant temperature strongly affects the etching rate and selectivity. We demonstrated self-organized formation of an array with a periodicity of 17 nm of dome-shaped Si0.82Ge0.18 nanodots with an aspect ratio of 0.12.
Detailed analysis of polyad-breaking spectroscopic Hamiltonians for multiple minima with above barrier motion: Isomerization in HO2
Authors: Barnes George L. , Kellman Michael E.
Published: February 2011

We present a two-dimensional model for isomerization in the hydroperoxyl radical (HO2). We then show that spectroscopic fitting Hamiltonians are capable of reproducing large scale vibrational structure above isomerization barriers. Two resonances, the 2:1 and 3:1, are necessary to describe the pertinent physical features of the system and, hence, a polyad-breaking Hamiltonian is required. We further illustrate, through the use of approximate wave functions, that inclusion of additional coupling terms yields physically unrealistic results despite an improved agreement with the exact energy levels. Instead, the use of a single diagonal term, rather than “extra” couplings, yields good fits with realistic results. Insight into the dynamical nature of isomerization is also gained through classical trajectories. Contrary to physical intuition the bend mode is not the initial “reaction mode,” but rather isomerization requires excitation in both the stretch and bend modes. The dynamics reveals a Farey tree formed between the 2:1 and 3:1 resonances with the prominent 5:2 (2:1 + 3:1) feature effectively dividing the tree into portions. The 3:1 portion is associated with isomerization, while the 2:1 portion leads to “localization” and perhaps dissociation at higher energies than those considered in this work. Simple single resonance models analyzed on polyad phase spheres are able to account in a qualitative way for the spectral, periodic orbit, and wave function patterns that we observe.
Effects of radially dependent parameters on proton transport in polymer electrolyte membrane nanopores
Authors: Ladipo Kehinde O. , Berg Peter , Kimmerle Sven-Joachim , Novruzi Arian
Published: February 2011

A three-dimensional continuum model is explored to investigate the effects of radially dependent system parameters, such as relative permittivity and viscosity, on the transport of proton and water in nanoscale cylindrical pores of a fully hydrated polymer electrolyte membrane (PEM). The model employs Poisson, Nernst–Planck, and Stokes equations. Based on evidence from the literature for the presence of a stagnant water layer near the pore surface, we assume that a no-slip surface is located inside the pore, a few Angstroms from the pore wall. To solve the system numerically, the steady-state solution for the transport of protons and water is considered to be a perturbation around the equilibrium solution. Our results indicate that a radial variation of relative permittivity has the greatest influence on pore conductivity, reducing it by about 50% when compared to that of constant permittivity. On the other hand, viscosity plays the dominant role when the effective water drag within such pores is considered. We conclude that a continuum approach, including constant viscosity, is applicable in nanoscale models provided that the location of the no-slip surface is properly specified and the radial variation of the relative permittivity is taken into consideration.
Exchange-spring behavior in nanopowders of CoFe2O4–CoFe2
Authors: Soares J. M. , Cabral F. A. O. , de Araújo J. H. , Machado F. L. A.
Published: February 2011

The nature of the magnetic interactions among core-shell nanoparticles of CoFe2O4–CoFe2 having an average particle size of 32 nm were investigated by δm plots. It was found that the interactions are mainly demagnetizing in nature for nanoparticles with core diameters larger than 26 nm. For smaller values of core diameters, the exchange-spring phenomenon takes place due to the exchange-coupling at the core-shell interface. The critical thickness of the shell was estimated to be 7.8 nm. The overall results are in excellent agreement with current theoretical models.
Heterogeneous immunoassays in microfluidic format using fluorescence detection with integrated amorphous silicon photodiodes
Authors: Pereira A. T. , Novo P. , Prazeres D. M. F. , Chu V. , Conde J. P.
Published: February 2011

Miniaturization of immunoassays through microfluidic technology has the potential to decrease the time and the quantity of reactants required for analysis, together with the potential of achieving multiplexing and portability. A lab-on-chip system incorporating a thin-film amorphous silicon (a-Si:H) photodiode microfabricated on a glass substrate with a thin-film amorphous silicon-carbon alloy directly deposited above the photodiode and acting as a fluorescence filter is integrated with a polydimethylsiloxane-based microfluidic network for the direct detection of antibody-antigen molecular recognition reactions using fluorescence. The model immunoassay used consists of primary antibody adsorption to the microchannel walls followed by its recognition by a secondary antibody labeled with a fluorescent quantum-dot tag. The conditions for the flow-through analysis in the microfluidic format were defined and the total assay time was 30 min. Specific molecular recognition was quantitatively detected. The measurements made with the a-Si:H photodiode are consistent with that obtained with a fluorescence microscope and both show a linear dependence on the antibody concentration in the nanomolar-micromolar range.
Visualization and interpretation of attosecond electron dynamics in laser-driven hydrogen molecular ion using Bohmian trajectories
Authors: Takemoto Norio , Becker Andreas
Published: February 2011

We analyze the attosecond electron dynamics in hydrogen molecular ion driven by an external intense laser field using the Bohmian trajectories. To this end, we employ a one-dimensional model of the molecular ion in which the motion of the protons is frozen. The Bohmian trajectories clearly visualize the electron transfer between the two protons in the field and, in particular, confirm the recently predicted attosecond transient localization of the electron at one of the protons and the related multiple bunches of the ionization current within a half cycle of the laser field. Further analysis based on the quantum trajectories shows that the electron dynamics in the molecular ion can be understood via the phase difference accumulated between the Coulomb wells at the two protons.