bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural and spectroscopic study of NaSbR(PO4)3 (R = Cr, Fe, In) phases
Authors: Aatiq Abderrahim , Tigha My Rachid
Published: November 2013

Crystallographic structures of the three NaSbR(PO4)3 (R = Cr, Fe, In) phases were determined at room temperature from X-ray powder diffraction (XRD) data using the Rietveld analysis. The three compounds belong to the Nasicon structural family. The presence of the (303) reflection in all XRD spectra of NaSbR(PO4)3 shows clearly that all compounds crystallise in rhombohedral system with R3 space group. Na atoms are practically ordered within the two positions, 3a and 3b, of M1 sites. Structure refinements show also a partially-ordered distribution of Sb5+ and R3+ ions within the Nasicon framework. A Raman and Infrared spectroscopic study was used to obtain further structural information about the nature of bonding in NaSbR(PO4)3 (R = Cr, Fe, In) phases.
Nullifying the extinction effect in XRD characterization of fibre textures
Authors: Tomov I. , Vassilev S.
Published: November 2013

To gain accuracy and, hence, physical reality of the data acquired by XRD measurements of fibre textures, a technique is elaborated to achieve experimental values, which are free of extinction effects. Its elaboration is based on combining basic definitions of the extinction theory and texture analysis. This technique is applicable to characterization of metal coatings that appear infinitely thick for X-rays. A nickel sample representing <100> + <221> texture components is used as a model. Resultant derived series of data on pole-density distribution of the {200} diffraction pole figure shows that the data corresponding to the main <100> texture component are strongly affected by extinction. On the contrary, due to definitions that require reduction of the intensity distribution to multiples of random density, the extinction-free values of the volume fraction of texture components do not differ substantially from those calculated by standard methods. Evidently, any of the standard methods for volume fraction measurements provides reasonable data if secondary extinction is even disregarded.
Metal hydride formation in palladium and palladium rich intermetallic compounds studied by in situ neutron diffraction
Authors: Kohlmann H. , Kurtzemann N. , Hansen T. C.
Published: November 2013

In order to investigate the hydrogenation of intermetallic compounds, a gas pressure cell for in situ neutron powder diffraction based on a sapphire crystal tube was constructed. By proper orientation of the single crystal Bragg peaks of the container material can be avoided, resulting in a very low diffraction background. Using a laser heating and gas pressure controller, the hydrogenation (deuteration) of palladium and palladium rich intermetallics was studied in real time up to 8 MPa gas pressure and 700 K. Crystal structure parameters of palladium deuterides could be obtained under various deuterium gas pressures, corresponding to compositional ranges of 0.04≤x≤0.11 for the α-phase and 0.52≤x≤0.72 for the β-phase at 446 K. In situ neutron powder diffraction of the deuteration of a thallium lead palladium intermetallic Tl1-xPbxPd3 shows two superstructures of the cubic closest packing (ccp) to transform independently into a AuCu3 type structure. This proves a direct reaction to the deuterium filled AuCu3 type structure instead of a reaction cascade involving different ccp superstructures and thus gives new insights into the reaction pathways of palladium rich intermetallic compounds.
Growth kinetics of Cu2ZnSnS4 thin films and powders
Authors: Müller M. , Azanza Ricardo C. L. , Di Maggio R. , Scardi P.
Published: November 2013

The growth kinetics of Cu2ZnSnS4 thin films and powders was studied using in-situ synchrotron data. Isothermal and isochronal measurements were performed at the MCX beamline of the Elettra synchrotron (Trieste, Italy). Diffraction line profile analysis was used to follow the changes in the domain size distribution during isothermal measurements, and the change in the mean volume of the domains was studied using the Johnson-Mehl-Avrami equation. The growth was found to be diffusion controlled from small dimensions while the nucleation rate is temperature dependent. An activation energy of 210 kJ/mol could be estimated. In case of the isochronal data, the evolution of inverse of the integral breadth of the diffraction peaks in dependence on temperature was studied using the Ozawa and Šatava equations. The activation energy determined for the growth process is between 112(2) and 145(5) kJ/mol.
Diffraction line broadening from nanocrystals under large hydrostatic pressures
Authors: Burgess Michael , Leonardi Alberto , Leoni Matteo , Scardi Paolo
Published: November 2013

Atomistic copper nanocrystals were investigated via Molecular Dynamics (MD) under hydrostatic pressure to probe the relationship between applied load and structure deformation. The corresponding X-ray powder diffraction patterns were generated from the atomic coordinates. The analysis followed both the traditional Williamson-Hall approach based on pseudo-Voigt fitting and an alternative, more accurate method able to derive the integral breadths without applying a fitting. The Williamson-Hall results show discrepancies not fully associated with an issue of fitting.
Ferroic phase transition in LaEr(MoO4)3
Authors: Hernández-Suárez A. , Guzmán-Afonso C. , López-Solano J. , González-Silgo C. , Torres M. E. , Sabalisck N. , Matesanz E. , Rodríguez-Carvajal J.
Published: November 2013

The ferroic phase transition in LaEr(MoO4)3 has been analyzed for the first time. It has been confirmed that this compound undergoes a phase transition from a tetragonal system (paraelectric-paraelastic phase), with space group P-421m [β-Gd2(MoO4)3 averaged phase] to an orthorhombic system (ferroelectric-ferroelastic phase), with space group Pba2 [β'-Gd2(MoO4)3 phase] in a reversible process. This phenomenon, together with the observed demixing at high temperature has been studied using different techniques. LaEr(MoO4)3 samples have been obtained by the conventional solid-state synthesis. The thermal dependence of the crystal structure was studied by powder X-ray and neutron diffraction, following a new refining procedure in which the symmetry modes of atomic displacements from the paraelectric-paraelastic structure were analyzed. Dielectric spectroscopy measurements have confirmed the structural results, showing a very smooth phase transition. Finally, calculations within the framework of Density Functional Theory show a behavior of the lattice parameters similar to that observed in our experiments.
X-ray powder diffraction and magnetic study of nominal Zn1-xNdxCr2Se4 – compounds (x = 0.05, 01)
Authors: Jendrzejewska Izabela , Zajdel Paweł , Maciążek Ewa , Sozańska Maria , Goryczka Tomasz
Published: November 2013

Polycrystalline compounds in the Zn1-xNdxCr2Se4 system were prepared by solid state reaction using selenides (ZnSe, Cr2Se3) and pure elements (Nd, Se) as starting materials. The structural properties were determined by X-ray diffraction and the chemical composition confirmed by SEM-EDX. The observed symmetry is cubic, space group Fd3m, while the lattice parameter varies from 10.4955(7)Å to 10.4976(7)Å, and is larger than for the pure matrix. The solubility limit for the current synthesis route lies below x = 0.1. The magnetic moments, effective and saturation, increase with increasing amount of Nd ions. The Neel temperature TN and ΘCW drop, respectively, to 17.4K and 81K for x = 0.1, independently indicating that neodymium is incorporated into the spinel lattice and promotes antiferromagnetic coupling between the Cr3+ ions.
Incidence and prevalence ofToxoplasma gondiiinfection in women in France, 1980–2020: model-based estimation
Authors: NOGAREDA F. , LE STRAT Y. , VILLENA I. , DE VALK H. , GOULET V.
Published: November 2013

Toxoplasmosis is a worldwide zoonosis due toToxoplasma gondii, a ubiquitous protozoan parasite of warm-blooded animals including humans. In pregnant women, primary infection can cause congenital toxoplasmosis resulting in severe malformations in the newborn. Since 1978, public health authorities in France have implemented a congenital toxoplasmosis prevention programme, including monthly serological screening of all seronegative pregnant women, and treatment in case of seroconversion. However, this programme does not produce systematic surveillance data on incidence and prevalence. Our objective was to estimate the incidence and prevalence ofT. gondiiinfection, and the incidence of seroconversion during pregnancy in women in France. We used a catalytic model to estimate incidence and prevalence ofToxoplasmainfection between 1980 and 2020 in women of childbearing age. We used age- and time-specific seroprevalence data obtained from the National Perinatal Surveys (NPS) conducted in 1995, 2003 and 2010. We assumed that incidence depends both on age and calendar time, and can be expressed as the product of two unknown functions. We also estimated incidence of seroconversion during pregnancy in 2010 from the NPS and the National Surveillance of Congenital Toxoplasmosis (ToxoSurv). We combined data of 42208 women aged 15–45 years with serology available from the three NPS. For women aged 30 years the modelled incidence decreased from 7·5/1000 susceptible women in 1980 to 3·5/1000 in 2000. In 2010 the incidence was 2·4/1000. The predicted incidence and prevalence for 2020 was 1·6/1000 and 27%, respectively. The incidence of seroconversion during pregnancy in 2010 was estimated at 2·1/1000 susceptible pregnant women (95% CI 1·3–3·1) from the NPS and 1·9 (95% CI 1·8–2·1) from ToxoSurv. Incidence and prevalence ofToxoplasmainfection has decreased markedly during the last 30 years. This decrease may be explained by a lower exposure to the parasite by changes in food habits and by improved hygiene practices in meat production. Modelled estimations were consistent with estimates observed in other studies conducted previously in France. The catalytic modelling provides reliable estimates of incidence and prevalence ofToxoplasmainfection over time. This approach might be useful for evaluating preventive programme for toxoplasmosis.
Healthcare workers and measles-mumps-rubella (MMR) status: how worried should we be about further outbreaks?
Authors: BASU S. , GIRI P. , ADISESH A. , McNAUGHT R.
Published: November 2013

Recently, a number of outbreaks of measles and mumps have occurred within the UK and Europe. Healthcare workers (HCWs) are at risk of contracting and transmitting disease to patients and staff. To examine this risk at the point of entry to healthcare, we assessed the serological results of new HCWs presenting for pre-placement clearance without evidence of measles-mumps-rubella (MMR) immunity between 1 April 2010 and 31 March 2012. Overall rates of serological positivity to MMR across all age groups were 88·2%, 68·8% and 93·9%, respectively. With regard to measles and mumps, there were statistically significant decreases in the percentage of HCWs born after 1980 that had positive serology (P < 0·05). No such differences were seen between healthcare groups. Most seronegative HCWs accepted MMR vaccination. Despite our entry-level findings, the ongoing risk of a MMR outbreak within this cohort of HCWs appears low.
Regimes of Memory: the Case of the Netherlands
Authors: Emmer Pieter
Published: November 2013

The Netherlands is not known for its opposing regimes of memory. There are two exceptions to this rule: the history of the German Occupation during the Second World War and the Dutch participation in the Atlantic slave trade and slavery. The relatively low numbers of survivors of the Holocaust in the Netherlands, as well as the volume and the profitability of the Dutch slave trade and slavery, and the importance of slave resistance in abolishing slavery in the Dutch Caribbean have produced conflicting views, especially between professional historians and the descendants of slaves living in the Netherlands.
The Memory of Fascism and of the Anti-Fascist Resistance among Italian Youth
Authors: Cavalli Alessandro
Published: November 2013

This paper discusses the reasons why Italian young people today are not in a position to develop a memory of their own regarding the fascist regime of the recent past. Neither families, nor schools and media, could transmit experiences and provide learning opportunities that enables young men and women to construct an adequate image of that period of their historical heritage. Fascism has become the object of a process of collective removal.
The Effect of Magnesium Ions on Chromosome Structure as Observed by Helium Ion Microscopy
Authors: Dwiranti Astari , Hamano Tohru , Takata Hideaki , Nagano Shoko , Guo Hongxuan , Onishi Keiko , Wako Toshiyuki , Uchiyama Susumu , Fukui Kiichi
Published: November 2013

One of the few conclusions known about chromosome structure is that Mg2+is required for the organization of chromosomes. Scanning electron microscopy is a powerful tool for studying chromosome morphology, but being nonconductive, chromosomes require metal/carbon coating that may conceal information about the detailed surface structure of the sample. Helium ion microscopy (HIM), which has recently been developed, does not require sample coating due to its charge compensation system. Here we investigated the structure of isolated human chromosomes under different Mg2+concentrations by HIM. High-contrast and resolution images from uncoated samples obtained by HIM enabled investigation on the effects of Mg2+on chromosome structure. Chromatin fiber information was obtained more clearly with uncoated than coated chromosomes. Our results suggest that both overall features and detailed structure of chromatin are significantly affected by different Mg2+concentrations. Chromosomes were more condensed and a globular structure of chromatin with 30 nm diameter was visualized with 5 mM Mg2+treatment, while 0 mM Mg2+resulted in a less compact and more fibrous structure 11 nm in diameter. We conclude that HIM is a powerful tool for investigating chromosomes and other biological samples without requiring metal/carbon coating.
Millon Clinical Multiaxial Inventory III (MCMI-III) and Communication Styles in a Sample of University Students
Authors: Caparrós Beatriz Caparrós , Hoz Esperanza Villar
Published: November 2013

Despite the controversy generated by the conceptualization of personality disorders, it is well established that the inflexibility of coping styles and dysfunctional behaviors associated with them can lead to a considerable impairment in interpersonal relationships. Although communication is one of the most important processes in relating to others, few empirical studies have been undertaken on the influence of dysfunctional personality patterns on communication styles, which is the main objective of the present cross-sectional study. A total of 529 Spanish university students were assessed using the Millon Clinical Multiaxial Inventory III (MCMI-III), Millon, Davis, and Millon, 1997, and the Communicator Style Measure (Norton, 1978). Results show statistically significant relationships between different personality patterns and styles of communication and suggest that narcissistic, histrionic and compulsive patterns are related to positive communication styles in a non-clinical sample. The implications of this study are discussed.
Academic Performance and Social Competence of Adolescents: Predictions based on Effortful Control and Empathy
Authors: Zorza Juan P. , Marino Julián , de Lemus Soledad , Acosta Mesas Alberto
Published: November 2013

This study explored the predictive power of effortful control (EC) on empathy, academic performance, and social competence in adolescents. We obtained self-report measures of EC and dispositional empathy in 359 students (197 girls and 162 boys) aged between 12 and 14 years. Each student provided information about the prosocial behavior of the rest of his/her classmates and completed a sociogram. At the end of the school year, we calculated the mean grade of each student and the teacher responsible for each class completed a questionnaire on the academic skills of his/her students. The study confirmed the existence of a structural equation model (SEM) in which EC directly predicted academic performance and social competence. Additionally, empathic concern partially mediated the effect of EC on social competence. Finally, social competence significantly predicted academic performance. The article discusses the practical applications of the model proposed.
Semantic Conflict Processing in the Color-Word Stroop and the Emotional Stroop
Authors: Zurrón Montserrat , Ramos-Goicoa Marta , Díaz Fernando
Published: November 2013

With the aim of establishing the temporal locus of the semantic conflict in color-word Stroop and emotional Stroop phenomena, we analyzed the Event-Related Potentials (ERPs) elicited by nonwords, incongruent and congruent color words, colored words with positive and negative emotional valence, and colored words with neutral valence. The incongruent, positive, negative, and neutral stimuli produced interference in the behavioral response to the color of the stimuli. The P150/N170 amplitude was sensitive to the semantic equivalence of both dimensions of the congruent color words. The P3b amplitude was smaller in response to incongruent color words and to positive, negative, and neutral colored words than in response to the congruent color words and colored nonwords. There were no differences in the ERPs induced in response to colored words with positive, negative, and neutral valence. Therefore, the P3b amplitude was sensitive to interference from the semantic content of the incongruent, positive, negative, and neutral words in the color-response task, independently of the emotional content of the colored words. In addition, the P3b amplitude was smaller in response to colored words with positive, negative, and neutral valence than in response to the incongruent color words. Overall, these data indicate that the temporal locus of the semantic conflict generated by the incongruent color words (in the color-word Stroop task) and by colored words with positive, negative, and neutral valence (in the emotional Stroop task) appears to occur in the range 300–450 ms post-stimulus.
Electrophysiological Correlates of Perceptual Auditory Priming Without Explicit Recognition Memory
Authors: Harris Jill D. , Cutmore Tim R. H. , O’Gorman John , Finnigan Simon , Shum David H. K.
Published: November 2013

The aim of this study was to identify an event-related potential (ERP correlate) of perceptual auditory priming using a method that can dissociate it from explicit memory similar to Rugg et al. (1998) . EEG was recorded during performance of an auditory word recognition test, where 17 participants discriminated “old” from “new” aural words, encoded using either a “deep” or “shallow” levels-of-processing (LOP) study task. A right-lateralized P200 effect was modulated by words’ old/new status but not by accuracy of recognition or LOP manipulation. Because this effect was driven by simple repetition rather than factors known to influence episodic recognition memory, a “bottom-up” perceptual priming function was inferred which was substantiated by its early temporal appearance. A similar ERP amplitude modulation was evident across a broader topographical region during the subsequent N400 time interval. Conversely the late posterior component (LPC; 500–800 ms) for deeply-encoded, correctly-recognized words was of higher amplitude than LPCs for shallowly-encoded and new words, consistent with proposals that this ERP component indexes episodic memory. To our knowledge this is the first report of an ERP correlate of auditory perceptual priming dissociated from explicit episodic memory.
Isotopic signatures of N2O produced by ammonia-oxidizing archaea from soils
Authors: Jung Man-Young , Well Reinhard , Min Deullae , Giesemann Anette , Park Soo-Je , Kim Jong-Geol , Kim So-Jeong , Rhee Sung-Keun
Published: November 2013

N2O gas is involved in global warming and ozone depletion. The major sources of N2O are soil microbial processes. Anthropogenic inputs into the nitrogen cycle have exacerbated these microbial processes, including nitrification. Ammonia-oxidizing archaea (AOA) are major members of the pool of soil ammonia-oxidizing microorganisms. This study investigated the isotopic signatures of N2O produced by soil AOA and associated N2O production processes. All five AOA strains (I.1a, I.1a-associated and I.1b clades of Thaumarchaeota) from soil produced N2O and their yields were comparable to those of ammonia-oxidizing bacteria (AOB). The levels of site preference (SP), δ15Nbulk and δ18O -N2O of soil AOA strains were 13–30%, −13 to −35% and 22–36%, respectively, and strains MY1–3 and other soil AOA strains had distinct isotopic signatures. A 15N-NH4+-labeling experiment indicated that N2O originated from two different production pathways (that is, ammonia oxidation and nitrifier denitrification), which suggests that the isotopic signatures of N2O from AOA may be attributable to the relative contributions of these two processes. The highest N2O production yield and lowest site preference of acidophilic strain CS may be related to enhanced nitrifier denitrification for detoxifying nitrite. Previously, it was not possible to detect N2O from soil AOA because of similarities between its isotopic signatures and those from AOB. Given the predominance of AOA over AOB in most soils, a significant proportion of the total N2O emissions from soil nitrification may be attributable to AOA.
Gadolinium-binding cyclic hexapeptoids: synthesis and relaxometric properties
Authors: De Cola Chiara , Fiorillo Gaetano , Meli Alessandra , Aime Silvio , Gianolio Eliana , Izzo Irene , De Riccardis Francesco
Published: November 2013

Cyclic hexapeptoids are able to efficiently bind Gd3+ions. Their thermodynamic stabilities have been assessed by1H-relaxometric investigations.
One-pot synthesis of highly fluorescent polycyclic benzimidazole derivatives
Authors: Manna Susanta Kumar , Mondal Suresh Kumar , Ahmed Atiur , Mandal Arabinda , Jana Atanu , Ikbal Mohammed , Samanta Shubhankar , Ray Jayanta K.
Published: November 2013

An efficient one pot synthesis of polycyclic benzimidazole derivatives has been developed (up to 90% yield).
Superior dye adsorption capacity of amorphous WO3 sub-micrometer rods fabricated by glancing angle deposition
Authors: Basnet Pradip , Zhao Yiping
Published: November 2013

Amorphous WO3 sub-micrometer rods fabricated by glancing angle deposition have superior cationic-dye adsorption capability, similar to that of activated carbon.
Four-and-a-half LIM domains proteins are novel regulators of the protein kinase D pathway in cardiac myocytes
Authors: Stathopoulou Konstantina , Cuello Friederike , Candasamy Alexandra J. , Kemp Elizabeth M. , Ehler Elisabeth , Haworth Robert S. , Avkiran Metin
Published: November 2013

PKD (protein kinase D) is a serine/threonine kinase implicated in multiple cardiac roles, including the phosphorylation of the class II HDAC5 (histone deacetylase isoform 5) and thereby de-repression of MEF2 (myocyte enhancer factor 2) transcription factor activity. In the present study we identify FHL1 (four-and-a-half LIM domains protein 1) and FHL2 as novel binding partners for PKD in cardiac myocytes. This was confirmed by pull-down assays using recombinant GST-fused proteins and heterologously or endogenously expressed PKD in adult rat ventricular myocytes or NRVMs (neonatal rat ventricular myocytes) respectively, and by co-immunoprecipitation of FHL1 and FHL2 with GFP–PKD1 fusion protein expressed in NRVMs. In vitro kinase assays showed that neither FHL1 nor FHL2 is a PKD1 substrate. Selective knockdown of FHL1 expression in NRVMs significantly inhibited PKD activation and HDAC5 phosphorylation in response to endothelin 1, but not to the α1-adrenoceptor agonist phenylephrine. In contrast, selective knockdown of FHL2 expression caused a significant reduction in PKD activation and HDAC5 phosphorylation in response to both stimuli. Interestingly, neither intervention affected MEF2 activation by endothelin 1 or phenylephrine. We conclude that FHL1 and FHL2 are novel cardiac PKD partners, which differentially facilitate PKD activation and HDAC5 phosphorylation by distinct neurohormonal stimuli, but are unlikely to regulate MEF2-driven transcriptional reprogramming.
Energy‐efficient replica detection for resource‐limited mobile devices in the internet of things
Authors: Cho Kwantae , Lee Byung‐Gil , Lee Kyungho , Lee Dong Hoon
Published: November 2013

The forthcoming Internet of Things – an intelligent collaboration of resource‐limited static/mobile devices that are embedded in the daily lives of users – poses new challenges to security and end‐user privacy. One of the most challenging problems is how to thwart replica attacks. Once a device is captured physically by an attacker or contaminated by malicious code, it can be reprogrammed and the secret information inside can be duplicated into a large number of replicas that maliciously occupy the network and collect users private information without authorisation. In this study, the authors focus on studying the detection of replicas in mobile applications; which can consist of resource‐limited static devices attached to mobile entities. Most existing solutions for detecting replicas have been designed for static devices, and cannot be immediately applied to mobile devices because of their unique properties, in particular, their node mobility. The authors present two efficient methods for detecting replicas in mobile devices. Through performance evaluations, they find that the proposed methods provide highly accurate replica detection with nearly zero detection errors. Furthermore, the distributed and cooperative strategy of the methods significantly reduces the energy required to detect replicas while providing faster replica detection than the existing solutions.
Consensus of a leader‐following multi‐agent system with negative weights and noises
Authors: Hu Ai‐Hua , Cao Jin‐De , Hu Man‐Feng , Guo Liu‐Xiao
Published: November 2013

This study is concerned with the issue of mean‐square consensus for a model of leader‐following multi‐agent system. The agents acting as followers update states based on the information received from the time varying neighbours and the virtual leader. Negative weights besides positive weights are introduced for the links existing among the agents. Moreover, all followers considered here are influenced by noises with different intensities emerging from the external environment or transmission channels. In order to guarantee consensus of the multi‐agent system under the noises, the corresponding sufficient conditions are derived. Theoretical proofs are given mainly by using the Lyapunov function approach and the stochastic analysis. Finally, some numerical examples are presented to demonstrate the effectiveness of the results.
Optimal control of single spin‐1/2 quantum systems
Authors: Fu Shizhou , Chen Michael Z.Q.
Published: November 2013

The purpose of this study is to explore the optimal control problems for a class of single spin‐1/2 quantum ensembles. The system in question evolves on a manifold in ℛ3 and is modelled as a bilinear control form whose states are represented as coherence vectors. An associated matrix Lie group system with state space SO (3) is introduced in order to facilitate solving the given problem. The controllability as well as the reachable set of the system is first analysed in detail. Then, the maximum principle is applied to the optimal control for system evolving on the Lie group of special orthogonal matrices of dimension 3, with cost that is quadratic in the control input. As an illustrative example, the authors apply their result to perform a reversible logic quantum operation NOT on single spin‐1/2 system. Explicit expressions for the optimal control are given which are linked to the initial state of the system.
New approach to second‐order sliding mode control design
Authors: Ding Shihong , Li Shihua , Zheng Wei Xing
Published: November 2013

The second‐order sliding mode control generates important properties for closed‐loop systems, such as robustness, disturbance rejection and finite‐time convergence. In this study, it is shown that the adding a power technique plus the nested saturation method will bring in a new second‐order sliding mode control scheme for non‐linear systems with relative degree two. Based on this, a second‐order sliding mode controller is constructed by imposing a natural assumption on the sliding mode dynamics, that is, the uncertainty of the sliding mode dynamics can be bounded by a known function instead of a constant. Under the proposed sliding mode controller, it is proved that the closed‐loop system is not only globally convergent, but also locally finite‐time stable, which implies the global finite‐time stability. Finally, the effectiveness of the proposed method is verified by a numerical example.
Experimentally validated partial least squares model for dynamic line rating
Authors: Morrow David John , Fu Jiao , Abdelkader Sobhy Mohamed
Published: November 2013

This study presents a model based on partial least squares (PLS) regression for dynamic line rating (DLR). The model has been verified using data from field measurements, lab tests and outdoor experiments. Outdoor experimentation has been conducted both to verify the model predicted DLR and also to provide training data not available from field measurements, mainly heavily loaded conditions. The proposed model, unlike the direct measurement based DLR techniques, enables prediction of line rating for periods ahead of time whenever a reliable weather forecast is available. The PLS approach yields a very simple statistical model that accurately captures the physical performance of the conductor within a given environment without requiring a predetermination of parameters as required by many physical modelling techniques. Accuracy of the PLS model has been tested by predicting the conductor temperature for measurement sets other than those used for training. Being a linear model, it is straightforward to estimate the conductor ampacity for a set of predicted weather parameters. The PLS estimated ampacity has proven its accuracy through an outdoor experiment on a piece of the line conductor in real weather conditions.
Correlation between structural, magnetic, and dielectric properties of manganese substituted cobalt ferrite
Authors: Ramana C. V. , Kolekar Y. D. , Kamala Bharathi K. , Sinha B. , Ghosh K.
Published: November 2013

Manganese (Mn) substituted cobalt ferrites (CoFe2−xMnxO4, referred to CFMO) were synthesized and their structural, magnetic, and dielectric properties were evaluated. X-ray diffraction measurements coupled with Rietveld refinement indicate that the CFMO materials crystallize in the inverse cubic spinel phase. Temperature (T = 300 K and 10 K) dependent magnetization (M(H)) measurements indicate the long range ferromagnetic ordering in CoFe2−xMnxO4 (x = 0.00–0.15) ferrites. The cubic anisotropy constant (K1(T)) and saturation magnetization (Ms(T)) were derived by using the “law of approach” to saturation that describes the field dependence of M(H) for magnetic fields much higher than the coercive field (Hc). Saturation magnetization (Ms), obtained from the model, decreases with increasing temperature. For CoFe2O4, Ms decreases from 3.63 μB per formula unit (f.u.) to 3.47 μB/f.u. with increasing temperature from 10 to 300 K. CFMO (0.00–0.15) exhibit the similar trend while the magnitude of Ms is dependent on Mn-concentration. Ms-T functional relationship obeys the Bloch's law. The lattice parameter and magnetic moment calculated for CFMO reveals that Mn ions occupying the Fe and Co position at the octahedral site in the inverse cubic spinel phase. The structure and magnetism in CFMO are further corroborated by bond length and bond angle calculations. The dielectric constant dispersion of CFMO in the frequency range of 20 Hz–1 MHz fits to the modified Debye's function with more than one ion contributing to the relaxation. The relaxation time and spread factor derived from modeling the experimental data are ∼10−4 s and ∼0.35(±0.05), respectively.
Metrics for measuring distances in configuration spaces
Authors: Sadeghi Ali , Ghasemi S. Alireza , Schaefer Bastian , Mohr Stephan , Lill Markus A. , Goedecker Stefan
Published: November 2013

In order to characterize molecular structures we introduce configurational fingerprint vectors which are counterparts of quantities used experimentally to identify structures. The Euclidean distance between the configurational fingerprint vectors satisfies the properties of a metric and can therefore safely be used to measure dissimilarities between configurations in the high dimensional configuration space. In particular we show that these metrics are a perfect and computationally cheap replacement for the root-mean-square distance (RMSD) when one has to decide whether two noise contaminated configurations are identical or not. We introduce a Monte Carlo approach to obtain the global minimum of the RMSD between configurations, which is obtained from a global minimization over all translations, rotations, and permutations of atomic indices.
Extreme density-driven delocalization error for a model solvated-electron system
Authors: Johnson Erin R. , Otero-de-la-Roza A. , Dale Stephen G.
Published: November 2013

Delocalization (or charge-transfer) error is one of the scarce but spectacular failures of density-functional theory. It is particularly apparent in extensively delocalized molecules, and manifests in the calculation of bandgaps, reaction barriers, and dissociation limits. Even though delocalization error is always present in the self-consistent electron density, the differences from reference densities are often quite subtle and the error tends to be driven by the exchange-correlation energy expression. In this article, we propose a model system (the Kevan model) where approximate density functionals predict dramatically different charge distributions because of delocalization error. The model system consists of an electron trapped in a water hexamer and is a finite representation of an experimentally observed class of solids: electrides. The Kevan model is of fundamental interest because it allows the estimation of charge transfer error without recourse to fractional charge calculations, but our results are also relevant in the context of the modeling of confined electrons in density-functional theory.
Graph representation of protein free energy landscape
Authors: Li Minghai , Duan Mojie , Fan Jue , Han Li , Huo Shuanghong
Published: November 2013

The thermodynamics and kinetics of protein folding and protein conformational changes are governed by the underlying free energy landscape. However, the multidimensional nature of the free energy landscape makes it difficult to describe. We propose to use a weighted-graph approach to depict the free energy landscape with the nodes on the graph representing the conformational states and the edge weights reflecting the free energy barriers between the states. Our graph is constructed from a molecular dynamics trajectory and does not involve projecting the multi-dimensional free energy landscape onto a low-dimensional space defined by a few order parameters. The calculation of free energy barriers was based on transition-path theory using the MSMBuilder2 package. We compare our graph with the widely used transition disconnectivity graph (TRDG) which is constructed from the same trajectory and show that our approach gives more accurate description of the free energy landscape than the TRDG approach even though the latter can be organized into a simple tree representation. The weighted-graph is a general approach and can be used on any complex system.
Transport mechanisms and effective Schottky barrier height of ZnO/a-Si:H and ZnO/μc-Si:H heterojunction solar cells
Authors: Corpus-Mendoza Asiel N. , De Souza M. M. , Hamelmann Frank
Published: November 2013

The impact of boron doping on the p-layer of thin film silicon solar cells is assessed by measuring the effective Schottky barrier height of ZnO/a-Si:H and ZnO/μc-Si:H heterojunctions. A deviation from ideal diode characteristics is revealed by an increase of ideality factor with doping concentration. Higher current densities and lower effective Schottky barriers are evaluated for higher doping levels, resulting in increasingly Ohmic behaviour. This is attributed to an enhancement of tunneling through a thinner depletion region, as supported by computer simulations. Extracted barriers are in the range of 0.7–1 eV for the heterojunctions with rectifying behaviour.
Analytical surface-potential-based drain current model for amorphous InGaZnO thin film transistors
Authors: Tsormpatzoglou A. , Hastas N. A. , Choi N. , Mahmoudabadi F. , Hatalis M. K. , Dimitriadis C. A.
Published: November 2013

A fully analytical surface-potential-based drain current model for amorphous InGaZnO (α-IGZO) thin film transistors (TFTs) has been developed based on a Gaussian distribution of subgap states, with the central energy fixed at the conduction band edge, which is approximated by two exponential distributions. This model includes both drift and diffusion components to describe the drain current in all regions of operation. Using an empirical mobility relationship that depends on both horizontal and vertical electric field, it is demonstrated that the model describes accurately the experimental transfer and output characteristics, making the model suitable for the design of circuits using α-IGZO TFTs.
High-field half-cycle terahertz radiation from relativistic laser interaction with thin solid targets
Authors: Ding W. J. , Sheng Z. M. , Koh W. S.
Published: November 2013

It is found that half-cycle terahertz (THz) pulses with the peak field over 100 MV/cm can be produced in ultrashort intense laser interactions with thin solid targets. These THz pulses are shown to emit from both the front and rear sides of the solid target and are attributed to the coherent transition radiation by laser-produced ultrashort fast electron bunches. After the primary THz pulses, subsequent secondary half-cycle pulses are generated while some refluxing electrons cross the vacuum-target interfaces. Since such strong THz radiation is well synchronized with the driving lasers, it is particularly suitable for applications in various pump-probe experiments.
Charge exchange and ionization cross sections of H+ + H collision in dense quantum plasmas
Authors: Zhang Ling-yu , Qi Xin , Zhao Xiao-ying , Meng Dong-yuan , Xiao Guo-qing , Duan Wen-shan , Yang Lei
Published: November 2013

The plasma screening effects of dense quantum plasmas on H+ + H charge exchange and ionization cross sections are calculated by the classical trajectory Monte Carlo method. For charge exchange cross sections, it is found that the screening effects reduce cross sections slightly in weak screening conditions. However, cross sections are reduced substantially in strong screening conditions. For ionization cross sections, with the increase of screening effects, cross sections for low energies increase more rapidly than those for high energies. When the screening effects are strong enough, it is found that ionization cross sections decrease with the increase of incident H+ energy. In addition, the cross sections have been compared with those in weakly coupled plasmas. It is found that in weak screening conditions, plasma screening effects in the two plasmas are approximately the same, while in strong screening conditions, screening effects of dense quantum plasmas are stronger than those of weakly coupled plasmas.
Reduction of open circuit voltage loss in a polymer photovoltaic cell via interfacial molecular design: Insertion of a molecular spacer
Authors: Bilby David , Amonoo Jojo , Sykes Matthew E. , Frieberg Bradley , Huang Bingyuan , Hungerford Julian , Shtein Max , Green Peter , Kim Jinsang
Published: November 2013

Loss to the open circuit voltage (Voc) in organic photovoltaic cells is a critical bottleneck to achieving high power conversion efficiency. We demonstrate that the insertion of multilayers of a poly(phenylene ethynylene) spacer into the planar heterojunction between poly(3-hexylthiophene) and phenyl-C61-butyric acid methyl ester incrementally escalates the Voc of a polymer solar cell from 0.43 V to 0.9 V. Through a combination of light intensity and temperature dependent measurements, we show that this control over the molecular structure local to the interface increases Voc by raising the polaron pair energy and by suppressing the dark-diode current.
Growth and characterization of hybrid insulating ferromagnet-topological insulator heterostructure devices
Authors: Kandala A. , Richardella A. , Rench D. W. , Zhang D. M. , Flanagan T. C. , Samarth N.
Published: November 2013

We report the integration of the insulating ferromagnet GdN with epitaxial films of the topological insulator Bi2Se3 and present detailed structural, magnetic, and transport characterization of the heterostructures. Fabrication of multi-channel Hall bars with bare and GdN-capped sections enable direct comparison of magnetotransport properties. We show that the presence of the magnetic overlayer results in suppression of weak anti-localization at the top surface.
Extremely robust and conformable capacitive pressure sensors based on flexible polyurethane foams and stretchable metallization
Authors: Vandeparre H. , Watson D. , Lacour S. P.
Published: November 2013

Microfabricated capacitive sensors prepared with elastomeric foam dielectric films and stretchable metallic electrodes display robustness to extreme conditions including stretching and tissue-like folding and autoclaving. The open cellular structure of the elastomeric foam leads to significant increase of the capacitance upon compression of the dielectric membrane. The sensor sensitivity can be adjusted locally with the foam density to detect normal pressure in the 1 kPa to 100 kPa range. Such pressure transducers will find applications in interfaces between the body and support surfaces such as mattresses, joysticks or prosthetic sockets, in artificial skins and wearable robotics.
First record of a bicephalic chondrichthyan found in Australian waters; the southern fiddler ray, Trygonorrhina dumerilii (Chondrichthyes: Rhinobatidae)
Authors: Guida Leonardo , Walker Terence I. , Reina Richard D.
Published: November 2013

We report the first documented case of bicephaly in a chondrichthyan, the southern fiddler ray, Trygonorrhina dumerilii, in Australian waters. Females in the latter stages of pregnancy, as confirmed by ultrasound, were captured by hand in Swan Bay, Victoria (38.252°S, 144.616°E) in February 2013 and transported to aquaria. Up to 10 females gave birth in aquaria in early April 2013 to 11 neonates, one of which was a still-born, bicephalic neonate. Magnetic resonance imagery of the bicephalic neonate displayed the presence of two parallel vertebral columns running the entire length of the animal, diverging into two well formed heads. Morphological measurements were also made, comparing the bicephalic neonate to normal neonates. The cause of bicephaly is unknown, although congenital and environmental stressors during development may cause this condition.
Influence of climate and environment on post-fire recovery of mountain big sagebrush
Authors: Nelson Zachary J. , Weisberg Peter J. , Kitchen Stanley G.
Published: November 2013

In arid and semi-arid landscapes around the world, wildfire plays a key role in maintaining species diversity. Dominant plant associations may depend upon particular fire regime characteristics for their persistence. Mountain shrub communities in high-elevation landscapes of the Intermountain West, USA, are strongly influenced by the post-fire recovery dynamics of the obligate-seeding shrub, mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana [Rydb.] Beetle). This species is a short-distance disperser with a short-lived seedbank, leading to highly variable post-fire recovery times (15–100 years). We investigated the relative importance of site productivity and seasonal climate in explaining the variance in recovery time for 36 fires, comprising a fire chrono-sequence (from 1971 to 2007) for the Great Basin and Colorado Plateau. A. t. vaseyana recovery was positively related to precipitation in the cool season immediately following fire, likely because deep soil-water recharge that persists throughout the growing season enhances first-year seedling survival. Percentage sand fraction positively correlated with recovery rate yet negatively correlated with live cover in unburnt stands. Our data support the hypothesis that post-fire recovery rate of A. t. vaseyana depends on the climatically controlled ephemerality of the regeneration niche, as is likely true for many arid-land shrub species.
ARP2/3-mediated junction-associated lamellipodia control VE-cadherin–based cell junction dynamics and maintain monolayer integrity
Authors: Taha Abdallah Abu , Taha Muna , Seebach Jochen , Schnittler Hans-J.
Published: November 2013

Maintenance and remodeling of endothelial cell junctions critically depend on the VE-cadherin/catenin complex and its interaction with the actin filament cytoskeleton. Here we demonstrate that local lack of vascular endothelial (VE)-cadherin at established cell junctions causes actin-driven and actin-related protein 2/3 complex (ARP2/3)–controlled lamellipodia to appear intermittently at those sites. Lamellipodia overlap the VE-cadherin–free adjacent plasma membranes and facilitate formation of new VE-cadherin adhesion sites, which quickly move into the junctions, driving VE-cadherin dynamics and remodeling. Inhibition of the ARP2/3 complex by expression of the N-WASP (V)CA domain or application of two ARP2/3 inhibitors, CK-548 and CK-666, blocks VE-cadherin dynamics and causes intercellular gaps. Furthermore, expression of carboxy-terminal–truncated VE-cadherin increases the number of ARP2/3-controlled lamellipodia, whereas overexpression of wild-type VE-cadherin largely blocks it and decreases cell motility. The data demonstrate a functional interrelationship between VE-cadherin–mediated cell adhesion and actin-driven, ARP2/3-controlled formation of new VE-cadherin adhesion sites via intermittently appearing lamellipodia at established cell junctions. This coordinated mechanism controls VE-cadherin dynamics and cell motility and maintains monolayer integrity, thus potentially being relevant in disease and angiogenesis.