bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of an SDS‐gel electrophoresis method on SU‐8 microchips for protein separation with LIF detection: Application to the analysis of whey proteins
Authors: del Mar Barrios‐Romero Maria , Crevillén Agustín G. , Diez‐Masa José Carlos
Published: May 2013

This work describes the development of an SDS‐gel electrophoresis method for the analysis of major whey proteins (α‐lactalbumin, β‐lactoglobulin, and BSA) carried out in SU‐8 microchips. The method uses a low‐viscosity solution of dextran as a sieving polymer. A commercial coating agent (EOTrol LN) was added to the separation buffer to control the EOF of the chips. The potential of this coating agent to prevent protein adsorption on the walls of the SU‐8 channels was also evaluated. Additionally, the fluorescence background of the SU‐8 material was studied to improve the sensitivity of the method. By selecting an excitation wavelength of 532 nm at which the background fluorescence remains low and by replacing the mercury arc lamp by a laser in the detection system, an LOD in the nanomolar range was achieved for proteins derivatized with the fluorogenic reagent Chromeo P540. Finally, the method was applied to the analysis of milk samples, demonstrating the potential of SU‐8 microchips for the analysis of proteins in complex food samples.
Development and validation of HPLC coupled with triple quadrupole MS for the simultaneous determination of six phenolic acids, six flavonoids, and a lignan in Polygonum capitatum
Authors: Zhang Kaixia , Zhang Jun , Wei Shenghua , Jing Wenguang , Wang Yuesheng , Liu An
Published: May 2013

Polygonum capitatum, a traditional Miao medicinal plant, has significant effects on the treatment of urinary system infections and pyelonephritis. However, no study about the comprehensive quality evaluation of P. capitatum has been reported. In this contribution, a rapid and validated method based on HPLC coupled with triple quadrupole MS was established for the simultaneous determination of six active flavonoids, six phenolic acids, and a lignan in extracts of P. capitatum. These compounds were separated within 10 min on a C18 analytical column with gradient elution. All analyses were performed on an Agilent XDB C18 column (2.1 × 100 mm, 3.5 μm) with a linear gradient elution of acetonitrile/water. The proposed method was applied to analyze 15 batches of samples with acceptable linearity (r2, 0.9923–0.9992), precisions (RSD, 1.0–3.0%), repeatability (RSD, 2.0–3.2%), stability (RSD, 2.2–3.2%), and recovery (RSD, 2.1–3.6%) of the 13 compounds. These results demonstrated that this presented method was effective and reliable for the comprehensive quality evaluation of P. capitatum. Moreover, our study can provide chemical evidence to reveal the material basis of its therapeutic effects.
A method for multidimensional wave propagation analysis via component‐wise partition of longitudinal and shear waves
Authors: Cho S. S. , Park K. C. , Huh H.
Published: May 2013

An explicit integration algorithm for computations of discontinuous wave propagation in two‐dimensional and three‐dimensional solids is presented, which is designed to trace extensional and shear waves in accordance with their respective propagation speeds. This has been possible by an orthogonal decomposition of the total displacement into extensional and shear components, leading to two decoupled equations: one for the extensional waves and the other for shear waves. The two decoupled wave equations are integrated with their CFL time step sizes and then reconciled to a common step size by employing a previously developed front‐shock oscillation algorithm that is proven to be effective in mitigating spurious oscillations. Numerical experiments have demonstrated that the proposed algorithm for two‐dimensional and three‐dimensional wave propagation problems traces the stress wave fronts with high‐fidelity compared with existing conventional algorithms. Copyright © 2013 John Wiley & Sons, Ltd.
Thermal properties and side chain crystallinity of styrene and n‐alkyl methacrylate terpolymers
Authors: Karažija Tomislav , Vidović Elvira , Jukić Ante
Published: May 2013

Differential scanning calorimetry method was used for the study of thermal properties of terpolymers of styrene (ST) or methyl methacrylate (MMA) with dodecyl methacrylate and octadecyl methacrylate. Particularly, the interdependencies of the crystallinity content and composition of terpolymers were examined. The increase of the MMA or ST content in terpolymers resulted in the increased glass transition temperatures and decrease of the ratio of crystalline relative to amorphous phase (from 10% for xMMA = 10 mol% to 5.7% for xMMA = 30 mol%, and from 8.5% for xST = 16 mol% to 4% for xST = 40 mol%). These kinds of copolymers are commonly used as flow improvers at low temperatures for lubricating mineral oils; therefore a direct correlation between flow behavior of polymer solutions in mineral oil (pour point) and side‐chain crystallinity of copolymers was examined. Thus, by increasing the proportion of crystalline phases, i.e. the long‐chain alkyl methacrylates in copolymer, the pour point of oil solutions lowers. Thus, the solution of terpolymer with crystalline phase content of 4 mol% displays the pour point of −9°C while in those with crystalline phase content higher than 7 mol% pour point lowers below −30°C. POLYM. ENG. SCI., 53:2299–2307, 2013. © 2013 Society of Plastics Engineers
Influence of magnetic field on the dissolution profile of cotrimoxazole inserted into poly(lactic acid‐co‐glycolic acid) and maghemite nanocomposites
Authors: Pereira E.D. , Souza F.G. , Santana C.I. , Soares D.Q. , Lemos A.S. , Menezes L.R.
Published: May 2013

The antibiotic cotrimoxazole was associated with poly(lactic acid‐co‐glycolic acid) (PLGA) and maghemite, aiming to reach a controlled drug release system. PLGA was synthesized through the polycondensation of lactic acid and glycolic acid in an equimolar ratio, and maghemite was synthesized through the coprecipitation method. The drug cotrimoxazole was inserted in the composite through three different procedures: solution, fusion, and in situ to check the best insertion method. Several techniques were used to characterize the materials. The copolymer was characterized by nuclear magnetic resonance and size‐exclusion chromatography. In addition, the maghemite, the composites containing the drug, and the polymer were characterized by Fourier transform infrared spectroscopy (FTIR) with attenuated total reflectance device, small‐angle X‐ray scattering, and magnetic force, this last according to the methodology developed by our group. The root mean square error was used to compare the FTIR spectra of the samples, proving that the fusion method was the best way to insert the drug and maghemite in the polymer. Therefore, composites containing the drug and the nanoparticles were prepared by the fusion method. These composites were used for dissolution profile studies, which were monitored with and without magnetic field, aiming to understand the influence of the magnetic field on the dissolution profile. The dissolution was monitored and quantified using the ultraviolet‐visible spectrophotometry, following the United States Pharmacopeia (USP) method for cotrimoxazole tablets. Results demonstrated that nanocomposites presented a good magnetic force, able to keep the magnetic composite trapped in a specific place or tissue. The presence of the nanoparticles in the composites changed the kinetics of the drug release, as they constitute physical barriers to the drug diffusion, contributing to a sustained drug release process. Furthermore, in the presence of a magnetic field, the magnetic nanoparticles were able to perform a magnetic constriction of the material, making the drug release faster than in the absence of the magnetic field, which may be useful to perform a fine tuning of the system, allowing the easier adjustment of the speed and amount of released drug, useful to improve medical treatments and even the welfare of the patients. POLYM. ENG. SCI., 53:2308–2317, 2013. © 2013 Society of Plastics Engineers
The 3,5‐dinitroanilide anion: a singlet anilide anion with evidence for a thermally accessible triplet state
Authors: Perrotta Raffaele R. , Falvey Daniel E.
Published: May 2013

Anilide anions derived from deprotonation of 4‐nitroaniline and 3,5‐dinitroaniline were examined by using DFT calculations, as well as ultraviolet and 1H NMR experiments. The calculations indicate that the free anions are ground state singlets. However, when coordinated to a Li counterion, the 3,5‐dinitroanilide anion is predicted to have a very narrow gap between the singlet and the triplet state. Spectroscopic data is consistent with this prediction. The UV–Vis spectrum of this anion shows a maximum absorbance at approximately 310 nm, which is in reasonable agreement with the spectrum for the singlet anion calculated by time‐dependent density functional theory. On the other hand, NMR peak broadening and a modest Evans shift are consistent with the thermal population of a small amount of triplet anion. Copyright © 2013 John Wiley & Sons, Ltd.
Analysis of mural paintings using in situ non‐invasive XRF, FTIR spectroscopy and optical microscopy
Authors: Vornicu Nicoleta , Bibire Cristina , Murariu Elena , Ivanov Daniela
Published: May 2013

An analytical protocol consisting of X‐ray fluorescence spectroscopy, optical microscopy and Fourier transform infrared spectroscopy was used to study the origin and the nature of the materials (pigments, binders and coating preparation) of the Fundenii Doamnei church mural paint from Bucharest. The main interest of the present study consisted in the original votive paint from narthex, painted in 1757 in a secco technique.

During analysis, an unexpected pigment in the votive paint could be detected by the combined analytical techniques: ultramarine blue. Along with this pigment, the presence of gypsum binder based on egg and flax seed oil could also be evidenced. These results demonstrated a secco execution technique of the votive paint and also the presence of a restoration treatment. Moreover, during the present study, the components of the preparation layer and the constitutive pigments from both 1699 and 1757 years mural paints have been analyzed. Hence, the following pigments could be identified: vermilion, azurite, cinnabar, lead white, ochre, natural umber and gold, by using the combination of the analytical techniques.

The novelty of our results consists in detecting the composition of the materials used in this church painting (fresco and a secco) during these 254 years since its first restoration.

The results of these investigations pointed to the suitability of the non‐destructive and semi‐destructive analytical techniques in the complex characterization of the paints realized in different techniques, at different periods. Copyright © 2013 John Wiley & Sons, Ltd.
Identification of distinct nisin leader peptide regions that determine interactions with the modification enzymes NisB and NisC
Authors: Khusainov Rustem , Moll Gert N. , Kuipers Oscar P.
Published: May 2013

Nisin is the most prominent and applied bacteriocin that serves as a model for class I lantibiotics. The nisin leader peptide importantly determines interactions between precursor nisin and its modification enzymes NisB and NisC that mature nisin posttranslationally. NisB dehydrates serines and threonines, while NisC catalyzes the subsequent coupling of the formed dehydroamino acids to form lanthionines. Currently, little is known about how the nisin leader interacts with NisB and even less is known about its interactions with NisC. To investigate the nisin leader peptide requirements for functional interaction with the modification enzymes NisB and NisC, we systematically replaced six regions, of 2–4 amino acids each, with all‐alanine regions. By performing NisB and NisC co‐purification studies with these mutant leader peptides, we demonstrate that the nisin leader regions STKD(‐22‐19), FNLD(‐18‐15) and PR(‐2‐1) importantly contribute to the interactions of precursor nisin with both NisB and NisC, whereas the nisin leader region LVSV(‐14‐11) additionally contributes to the interaction of precursor nisin with NisC.
The dynamics of polycomb group proteins in early embryonic nervous system in mouse and human
Authors: Qi Lu , Jing‐Li Cao , Hu Yi , Yang Ji‐Gao , Ji Yuan , Huang Jing , Zhang Yi , Sun Da‐Guang , Xia Hong‐Fei , Ma Xu
Published: May 2013

Polycomb group (PcG) proteins are transcription regulatory proteins that control the expression of a variety of genes and the antero‐posterior neural patterning from early embryogenesis. Although expression of PcG genes in the nervous system has been noticed, but the expression pattern of PcG proteins in early embryonic nervous system is still unclear. In this study, we analyzed the expression pattern of PRC1 complex members (BMI‐1 and RING1B) and PRC2 complex members (EED, SUZ12 and EZH2) in early embryonic nervous system in mouse and human by Western blot and Immunohistochemistry. The results of Western blot showed that EED protein was significantly up‐regulated with the increase of the day of pregnancy during the early embryogenesis in mouse. BMI‐1 protein level was significantly increased from the day 10 of pregnancy, when compared with the day 9 of pregnancy. But the SUZ12, EZH2 and RING1B protein level did not change significantly. From the results of Immunohistochemistry, we found that the four PcG proteins were all expressed in the fetal brain and fetal spinal cord in mouse. In human, the expression of EED, SUZ12, and EZH2 was not significantly different in cerebral cortex and sacral spinal cord, but BMI‐1 and RING1B expression was enhanced with the development of embryos in early pregnancy. Collectively, our findings showed that PRC1 and PRC2 were spatiotemporally expressed in brain and spinal cord of early embryos.
Neutral Displacement Intravenous Connectors: Evaluating New Technology
Authors: Logan Renee
Published: May 2013

Background: The University Hospital of Northern British Columbia (UHNBC) utilized an opaque positive displacement intravenous (IV) line connector in 2011 and for several years previously. With concerns generated in the United States surrounding positive displacement and the potential increased risk for infection, as well as the training requirements related to ensuring that a proper clamping sequence was followed, a neutral displacement IV connector was implemented in October 2011.

Methods: Catheter-related blood stream infections and catheter occlusions were monitored at UHNBC for 4 months before (June through September 2011) and 4 months after (November 2011 through February 2012) the implementation of the neutral displacement IV connector by the Parenteral Services nursing team. A staff survey was conducted that reviewed the satisfaction with the newly implemented IV connector.

Results: The results of tracking catheter occlusions with a neutral displacement IV connector showed an average of 4.04 occlusions that required tissue plasminogen activator per 1,000 catheter days, compared with 5.47 occlusions that required tissue plasminogen activator per 1,000 catheter days with the positive displacement IV connector. During the evaluation period there was a 26% decrease in catheter occlusions with the implementation of the neutral displacement IV connector. Blood stream infection rates remained at zero for the entire evaluation with both displacement types of IV connectors. Nursing staff members were satisfied with the newly implemented IV connector.

Conclusions: UHNBC will continue to utilize the neutral displacement IV connector hospital-wide, and continues to monitor both catheter occlusions and catheter-related blood stream infections. Following UHNBC, facilities in the rest of Northern Health have implemented the neutral displacement IV connector.
Respect-Worthiness and Dignity
Authors: HAY CAROL
Published: May 2013

I argue that failing to fulfill the Kantian obligation to protect one’s rational nature might actually vitiate future instances of this obligation. To avoid this conclusion, I argue that, contrary to the received view among Kant scholars, the feature in virtue of which someone has unconditional and incomparable value is not the same feature in virtue of which she is owed the respect that constrains how she may be treated. Even though someone who fails to attempt to protect her rational nature fails to respect herself, and even though this moral failing does make her lose a certain kind of value, her obligations to respect herself remain.
La causalité revisitée à la lumière de la mécanique quantique
Authors: Vervoort Louis
Published: May 2013

Le principe de causalité (ou de déterminisme) et la notion de cause sont étudiés ici à la lumière de la mécanique quantique. Une définition du concept de cause est d’abord proposée. La question : «tout événement a-t-il une cause?» est ensuite abordée. Selon l’interprétation orthodoxe de la mécanique quantique, la réponse à cette question est négative. Mais il est soutenu ici que bien des arguments scientifiquement valables s’opposent à ce point de vue, et que la question du déterminisme reste donc d’ordre philosophique en non pas scientifique, comme le prétendent certains physiciens. Puisque le thème abordé est interdisciplinaire, nous avons voulu utiliser un langage compréhensible pour des généralistes des deux communautés, philosophes et physiciens.
Selection and Tuning of a Fast and Simple Phase-Contrast Microscopy Image Segmentation Algorithm for Measuring Myoblast Growth Kinetics in an Automated Manner
Authors: Juneau Pierre-Marc , Garnier Alain , Duchesne Carl
Published: May 2013

Acquiring and processing phase-contrast microscopy images in wide-field long-term live-cell imaging and high-throughput screening applications is still a challenge as the methodology and algorithms used must be fast, simple to use and tune, and as minimally intrusive as possible. In this paper, we developed a simple and fast algorithm to compute the cell-covered surface (degree of confluence) in phase-contrast microscopy images. This segmentation algorithm is based on a range filter of a specified size, a minimum range threshold, and a minimum object size threshold. These parameters were adjusted in order to maximize the F-measure function on a calibration set of 200 hand-segmented images, and its performance was compared with other algorithms proposed in the literature. A set of one million images from 37 myoblast cell cultures under different conditions were processed to obtain their cell-covered surface against time. The data were used to fit exponential and logistic models, and the analysis showed a linear relationship between the kinetic parameters and passage number and highlighted the effect of culture medium quality on cell growth kinetics. This algorithm could be used for real-time monitoring of cell cultures and for high-throughput screening experiments upon adequate tuning.
The Practical Process of Gender Mainstreaming in the Political Science Curriculum
Authors: Atchison Amy L.
Published: May 2013

Although the presence of women in the political science profession has increased rapidly since the 1980s, women still constitute less than 30% of the political science faculty nationwide and are more likely to find themselves in lower-paying and/or nontenure track positions (APSA 2011, 39; Evans and Moulder 2011). In the discipline, the position of gender and politics as a legitimate course of study has improved markedly since the 1970s (Lovenduski 1998; Mackay 2004; Murphy 2010; Tolleson-Rinehart and Carroll 2006). As Childs and Krook (2006, 19) point out, “mainstream editors, publishers and conference conveners no longer feel able to ignore the work of feminist political scientists.” But they also present evidence that this improvement stops short of full incorporation into the discipline and note that there is still skepticism about the value of feminist scholarship. This skepticism is also present at the intersection of the profession and discipline: while there are no systematic data on the employment of gender and politics scholars, it is not rare for a gender and politics scholar to be told that her employment prospects would be better if she were to research something else (Childs and Krook 2006). Given the position of women in the profession and the status of gender and politics in the discipline, it is unsurprising that there is continued resistance to integrating gender into mainstream political science education (Baldez 2010; Lovenduski 2005; Murphy 2010).
On the Therapeutic Aspects of Indian Classical Music
Authors: Dona Lasanthi Manaranjanie Kalinga
Published: May 2013

The positive impact of Indian classical music on human health is the subject of a deeply rooted belief in the Indian subcontinent and is also held among those who invest their time and efforts to Indian classical music elsewhere in the world. This article attempts to provide an account for such a widely shared belief, and singles out four essential components that contribute to it: The melodic rāga domain, the rhythmic tāla domain, time theory, and the extramusical rasa system. The discussion is developed from a general introduction to India to the specific therapeutic aspects of North Indian classical music. The author brings together up-to-date research and her first-hand experiences as a scholar and performer of North Indian classical music.
Mädchen mit Störungen des Sozialverhaltens
Authors: Stadler Christina , Euler Felix , Schwenck Christina
Published: May 2013

Unser Wissen zu Ursachen, Verlauf und Behandlungsoptionen von Patienten mit Störungen des Sozialverhaltens beschränkt sich überwiegend auf Studien an männlichen Patienten. In neueren Untersuchungen werden vermehrt weibliche Patientinnen berücksichtigt und geschlechtsassoziierte Unterschiede überprüft. Die vorliegende Arbeit gibt eine Übersicht über aktuelle Erkenntnisse zum psychopathologischen Erscheinungsbild und den neuropsychologischen Auffälligkeiten bei Mädchen mit Störungen des Sozialverhaltens. Es wird zudem die Frage berücksichtigt, ob auf der Basis der referierten Untersuchungsbefunde auf das Vorliegen geschlechtsspezifischer psychosozialer und neurobiologischer Risikofaktoren zu schließen ist. Implikationen für zukünftige Trends in der Forschung und Möglichkeiten für differentielle Behandlungsoptionen für Mädchen und Jungen werden diskutiert.
Tierquälerei als Symptom von Callous-Unemotional Traits bei inhaftierten Jungen und Mädchen
Authors: Sevecke Kathrin , Franke Sebastian , Krischer Maya K.
Published: May 2013

Tierquälerei zählt bei Kindern und Jugendlichen als Verhaltensauffälligkeit im Sinne der Störung des Sozialverhaltens. Die vorliegende Studie untersucht den Zusammenhang von Tierquälerei und Callous-Unemotional Traits (CU-Traits) als Psychopathy-Kerndimensionen bei inhaftierten Jungen und Mädchen (n = 334). Angewendet wurde die Psychopathy Checkliste für Jugendliche (PCL:YV). Es fanden sich bei den Jungen höchst signifikante Korrelationen zwischen den CU-Traits sowie den Psychopathy-Verhaltensdimensionen und Tierquälerei. Bei den Mädchen waren die Korrelationen geringfügig kleiner, fanden sich allerdings nicht für Tierquälerei und dem Interpersonalen Psychopathy-Faktor. Die männlichen Tierquäler zeigten sowohl für die CU-Traits als auch für die Psychopathy-Verhaltensdimensionen signifikant höhere PCL:YV-Werte als diejenigen Straftäter ohne Tierquälerei. Auch die weiblichen Tierquäler erreichten in allen Psychopathy-Dimensionen höhere Werte als die Nicht-Tierquäler bis auf den Interpersonalen Faktor. Diese Befunde wurden diskutiert und möglichen geschlechtsspezifischen Profilen zugeordnet. Tierquälerei scheint als Symptom für die Unterscheidung des Antisocial bzw. des Psychopathic Types der Antisozialen Persönlichkeitsstörung des DSM-V von Bedeutung zu sein.
Förderung malerischer (bildnerischer) Aktivitäten von Kindergarten- und Vorschulkindern
Authors: Kiese-Himmel Christiane
Published: May 2013

Sich durch Bilder und Zeichnungen auszudrücken, ist ein Urbedürfnis des Kindes. In einer narrativen Übersichtsarbeit werden malerische (bildnerische) Aktivitäten im jungen Kindesalter thematisiert. Diese dienen primär der senso-motorischen Förderung und der des räumlichen Denkens als basale Voraussetzung zur Ausbildung weiterer, insbesondere symbolbasierter, kognitiver Funktionen. In der Frühförderung, Entwicklungsförderung junger Kinder, Heilpädagogik und im Bildungswesen sind sie deshalb ein probates Fördermittel, da sie positive Transfereffekte auf andere Bereiche ermöglichen. Weil Früh- und Entwicklungsförderung immer stärker in das bildungspolitische Interesse rücken, stellt sich auch die Frage ihrer Wirksamkeit. Malerisch (bildnerisch) gestaltende Fördermaßnahmen von Nicht-Schulkindern werden in Deutschland (im Gegensatz zu musikalischer Förderung) selten evaluiert, sodass vergleichsweise wenige Erkenntnisse zu ihrer Wirksamkeit vorliegen. Zukünftiger Forschungsbedarf ist damit markiert. Methodische Probleme der Evaluation resultieren aus vielen mit dem Trainingseffekt konfundierenden Variablen.
Polarization effects on the solvation dynamics of coumarin C153 in ionic liquids: Components and their cross-correlations
Authors: Schmollngruber Michael , Schröder Christian , Steinhauser Othmar
Published: May 2013

The solvation dynamics of coumarin C153 dissolved in three selected molecular ionic liquids – EMIM+\documentclass[12pt]{minimal}\begin{document}${\rm BF}_4^-$\end{document} BF 4−, EMIM+TfO−, and BMIM+\documentclass[12pt]{minimal}\begin{document}${\rm BF}_4^-$\end{document} BF 4− – was studied by molecular dynamics simulations including polarization forces. The solvation response function was decomposed with respect to permanent and induced charge distributions, cationic and anionic contributions, and translational and non-translational motions. The latter decomposition was accomplished by an appropriate multipole expansion. Furthermore, the difference in solvation energy was resolved radially. The dynamics in the sub-picosecond regime was elucidated as the mutual translational motion of the solute and the cage formed by the first solvation shell. For a qualitative interpretation, solvent molecules can be reduced to “quasi-atomic” ions carrying a net charge at their molecular center of mass. Towards a quantitative description, the dipole moment serves as a measure of charge anisotropy.
Association effects in the {methanol + inert solvent} system via Monte Carlo simulations. I. Structure
Authors: Gómez-Álvarez Paula , Romaní Luis , González-Salgado Diego
Published: May 2013

In this work, the clusters residing in the {methanol + inert solvent} binary system have been characterized using a specific methodology in the framework of Monte Carlo molecular simulations. The cluster classification scheme considered distinguishes into five types: linear chains, cyclic clusters or isolated rings, branched linear chains, branched cyclic clusters, and composite rings. The procedure allows one to compute the next rich structural information: the fraction of molecules in the monomer or associated state, the fraction of each type of aggregate with a given size (and of molecules belonging to them), and the most probable and average cluster size for each type; likewise, the degree of branching in branched linear chains and the size distribution of the inner ring in branched cyclic clusters can be quantified. Specifically, all these properties were obtained for the {Optimized Potential for Liquid Simulation methanol + Lennard-Jones spheres} system at 298.15 K and 1 bar throughout the composition range. The results have provided a complete structural picture of this mixture describing comprehensively the effect of dilution into the hydrogen-bonded network of the pure associated fluid.
Simple analysis method for determining internal quantum efficiency and relative recombination ratios in light emitting diodes
Authors: Yoo Yang-Seok , Roh Tae-Moo , Na Jong-Ho , Son Sung Jin , Cho Yong-Hoon
Published: May 2013

We propose a facile analysis method for determining internal quantum efficiency (IQE) and relative carrier recombination ratios in light emitting diodes (LEDs). Using this method, IQE and different contributions of radiative and nonradiative recombination processes at arbitrary excitation power can be unambiguously determined without any knowledge of A, B, and C coefficients of the rate equation. We applied our analysis method to two LED samples grown on different substrates with distinct material quality and found good agreement with experimental results such as ω-rocking curve obtained by high resolution x-ray diffraction and decay lifetime measured by time-resolved photoluminescence.
Growth of polyphenyls via ion–molecule reactions: An experimental and theoretical mechanistic study
Authors: Aysina Julia , Maranzana Andrea , Tonachini Glauco , Tosi Paolo , Ascenzi Daniela
Published: May 2013

The reactivity of biphenylium cations C12H9+ with benzene C6H6 is investigated in a joint experimental and theoretical approach. Experiments are performed by using a triple quadruple mass spectrometer equipped with an atmospheric pressure chemical ion source to generate C12H9+ via dissociative ionization of various isomers of the neutral precursor hydroxybiphenyl (C12H10O). C–C coupling reactions leading to hydrocarbon growth are observed. The most abundant ionic products are C18H15+, C18H13+, C17H12+, and C8H7+. The dependence of product ion yields on the kinetic energy of reagent ions, as well as further experiments performed using partial isotopic labelling of reagents, support the idea that the reaction proceeds via a long lived association product, presumably the covalently bound protonated terphenyl C18H15+. Its formation is found to be exothermic and barrierless and, therefore, might occur under the low pressure and temperature conditions typical of planetary atmospheres and the interstellar medium. Theoretical calculations have focussed on the channel leading to C8H7+ plus C10H8, identifying, as the most probable fragments, the phenylethen-1-ylium cation and naphthalene, thus suggesting that the pathway leading to them might be of particular interest for the synthesis of polycyclic aromatic hydrocarbons. Both experiments and theory agree in finding this channel exoergic but hampered by small barriers of 2.7 and 3.7 kcal mol−1 on the singlet potential energy surface.
Accurate complex scaling of three dimensional numerical potentials
Authors: Cerioni Alessandro , Genovese Luigi , Duchemin Ivan , Deutsch Thierry
Published: May 2013

The complex scaling method, which consists in continuing spatial coordinates into the complex plane, is a well-established method that allows to compute resonant eigenfunctions of the time-independent Schrödinger operator. Whenever it is desirable to apply the complex scaling to investigate resonances in physical systems defined on numerical discrete grids, the most direct approach relies on the application of a similarity transformation to the original, unscaled Hamiltonian. We show that such an approach can be conveniently implemented in the Daubechies wavelet basis set, featuring a very promising level of generality, high accuracy, and no need for artificial convergence parameters. Complex scaling of three dimensional numerical potentials can be efficiently and accurately performed. By carrying out an illustrative resonant state computation in the case of a one-dimensional model potential, we then show that our wavelet-based approach may disclose new exciting opportunities in the field of computational non-Hermitian quantum mechanics.
Large-scale Dirac–Fock–Breit method using density fitting and 2-spinor basis functions
Authors: Kelley Matthew S. , Shiozaki Toru
Published: May 2013

We present an efficient theory and algorithm for computing four-component relativistic Dirac–Fock wave functions using the Coulomb, Gaunt, and full Breit interactions. Our implementation is based on density fitting, and is routinely applicable to systems with 100 atoms and a few heavy elements. The small components are expanded using 2-spinor basis functions. We show that the factorization of 3-index half-transformed integrals before building Coulomb and exchange matrices is essential for efficient evaluation of the Fock matrix. With the Coulomb interaction, the computational cost for evaluating the Fock operator has been found to be only 70–90 times that in the non-relativistic density-fitted Hartree–Fock method. The prefactors have been 170 and 350–450 for the Gaunt and Breit interactions, respectively. The largest molecule to which we have applied the Dirac–Fock–Coulomb method is an Ac(III) motexafin complex (130 atoms, 556 electrons, 1289 basis functions), for which one self-consistent iteration takes around 1100 s using 1024 CPU cores. In addition, we have found that, while the standard fitting basis sets are accurate for Dirac–Fock–Coulomb calculations, their accuracy is very poor for Dirac–Fock–Gaunt and Breit calculations. We report a prototype of accurate fitting basis sets for these cases.
Boron- and phosphorus-doped polycrystalline silicon thin films prepared by silver-induced layer exchange
Authors: Antesberger T. , Wassner T. A. , Jaeger C. , Algasinger M. , Kashani M. , Scholz M. , Matich S. , Stutzmann M.
Published: May 2013

Intentional boron and phosphorus doping of polycrystalline silicon thin films on glass prepared by the silver-induced layer exchange is presented. A silver/(titanium) oxide/amorphous silicon stack is annealed at temperatures below the eutectic temperature of the Ag/Si system, leading to a complete layer exchange and simultaneous crystallization of the amorphous silicon. Intentional doping of the amorphous silicon prior to the exchange process results in boron- or phosphorus-doped polycrystalline silicon. Hall effect measurements show carrier concentrations between 2×1017 cm−3 and 3×1020 cm−3 for phosphorus and 4×1018 cm−3 to 3×1019 cm−3 for boron-doped layers, with carrier mobilities up to 90 cm2/V s.
Focused ion beam and field-emission microscopy of metallic filaments in memory devices based on thin films of an ambipolar organic compound consisting of oxadiazole, carbazole, and fluorene units
Authors: Pearson Christopher , Bowen Leon , Lee Myung-Won , Fisher Alison L. , Linton Katharine E. , Bryce Martin R. , Petty Michael C.
Published: May 2013

We report on the mechanism of operation of organic thin film resistive memory architectures based on an ambipolar compound consisting of oxadiazole, carbazole, and fluorene units. Cross-sections of the devices have been imaged by electron microscopy both before and after applying a voltage. The micrographs reveal the growth of filaments, with diameters of 50 nm–100 nm, on the metal cathode. We suggest that these are formed by the drift of aluminium ions from the anode and are responsible for the observed switching and negative differential resistance phenomena in the memory devices.
Measurements of volume, thermal expansion, and specific heat in Zr57Cu15.4Ni12.6Al10Nb5 and Zr58.5Cu15.6Ni12.8Al10.3Nb2.8 liquids and glasses
Authors: Bendert J. C. , Blodgett M. E. , Gangopadhyay A. K. , Kelton K. F.
Published: May 2013

The temperature dependence of the specific volume, thermal expansion coefficient, and specific heat in the equilibrium, supercooled liquids, and glasses of the bulk metallic glass-forming alloys Zr57Cu15.4Ni12.6Al10Nb5 and Zr58.5Cu15.6Ni12.8Al10.3Nb2.8 are determined using the containerless electrostatic levitation technique. Such measurements have not been possible thus far because of rapid crystallization from the supercooled metastable liquids. The results show a decrease in the thermal expansion coefficient with decreasing temperature before the onset of the glass transition. The difference in the rate of decrease between the two alloys indicates larger structural contributions to the thermal expansion for the stronger liquid at high temperatures.
Effects of Pt capping layer on perpendicular magnet anisotropy in pseudo-spin valves of Ta/CoFeB/MgO/CoFeB/Pt magnetic-tunneling junctions
Authors: Lee Du-Yeong , Shim Tae-Hun , Park Jea-Gun
Published: May 2013

We investigated how the Pt capping layer affected perpendicular magnet anisotropy in magnetic-tunnel-junctions fabricated with a Ta electrode, a lower CoFeB layer, an MgO barrier, an upper CoFeB layer, and a Pt capping electrode, which was estimated by using an anisotropy constant multiplied by the upper CoFeB layer thickness (Ku * t). The maximum Ku * t was found at an annealing temperature of 300 °C for an magnetic tunnel junction with an upper CoFeB layer thickness of 0.9 nm, indicating a highly textured MgO (100) barrier of 1.0 nm with none of the remaining Pt inter-diffused in the upper CoFeB layer.
Graphene-coated holey metal films: Tunable molecular sensing by surface plasmon resonance
Authors: Reckinger Nicolas , Vlad Alexandru , Melinte Sorin , Colomer Jean-François , Sarrazin Michaël
Published: May 2013

We report on the enhancement of surface plasmon resonances in a holey bidimensional grating of subwavelength size, drilled in a gold thin film coated by a graphene sheet. The enhancement originates from the coupling between charge carriers in graphene and gold surface plasmons. The main plasmon resonance peak is located around 1.5 μm. A lower constraint on the gold-induced doping concentration of graphene is specified and the interest of this architecture for molecular sensing is also highlighted.
Effect of Ag nanoparticles integrated within antireflection coatings for solar cells
Authors: Cortés-Juan F. , Chaverri Ramos C. , Connolly J. P. , David C. , García de Abajo F. J. , Hurtado J. , Mihailetchi V. D. , Ponce-Alcántara S. , Sánchez Guillermo
Published: May 2013

The influence of the relative position of Ag metallic nanoparticles (Ag MNPs) embedded in a 100 nm SiOx Antireflection Coating (ARC) for specular polished c-Si substrates is studied. It is demonstrated that this Plasmonic ARC (PARC) can achieve lower average reflectivities than the optimised SiOx ARC. This has been done for different sizes of Ag nanoparticles. An alternative for PECVD to encapsulate Ag MNPs with SiOx is presented, avoiding the risk of metallic contamination in the reactor chamber as well as its effect on the size and shape of the self-aggregated Ag MNP. It is demonstrated, however, that this PARC is not suitable for silicon solar cells as a substitute for traditional ARC because it presents a high loss related with Fano destructive interference.
Broadband anomalous reflection based on gradient low-Q meta-surface
Authors: Pu Mingbo , Chen Po , Wang Changtao , Wang Yanqin , Zhao Zeyu , Hu Chenggang , Huang Cheng , Luo Xiangang
Published: May 2013

Gradient–index metamaterial is crucial in the spatial manipulation of electromagnetic wave. Here we present an efficient approach to extend the bandwidth of phase modulation by utilizing the broadband characteristic of low-quality (Q) meta-surface in the reflection mode. The dispersion of the meta-surface is engineered to compensate the phase difference induced by frequency change. Meanwhile, a thin gradient index cover layer is added on the top of meta-surface to extend the phase modulation range to cover the entire [0, 360°]. As a proof of concept, anomalous nearly perfect reflection with relative bandwidth near 40% is demonstrated in the microwave regime.
Haptic Choice Blindness
Authors: Steenfeldt-Kristensen Catherine , Thornton Ian M.
Published: May 2013

Choice blindness is the failure to notice a mismatch between intention and outcome when making decisions. It is unknown whether choice blindness occurs when participants have extended interaction with real objects. Here, we examined the case when objects could be touched but not seen. Participants examined pairs of common, everyday objects inside a specially constructed box where a silent turntable was used to switch objects between initial choice and later justification. For similar pairs of objects, we found detection rates of around 22%, consistent with previous studies of choice blindness. For pairs consisting of more distinctive exemplars, the detection rate rose to 70%. Our results indicate that choice blindness does occur after haptic interaction with real objects, but is strongly modulated by similarity.
Nutritional management of the transition cow in the 21st century – a paradigm shift in thinking
Authors: Roche J. R. , Bell A. W. , Overton T. R. , Loor J. J.
Published: May 2013

The transition period is defined as the 6–8 weeks encompassing late pregnancy and early lactation, involving coordinated changes across multiple tissues and an enormous increase in nutrient requirements. Failure to transition successfully can result in reduced DM intake, milk production, delayed oestrus, failure to conceive and increased incidence of metabolic and infectious diseases, many of which are inter-related. Modern technologies have enabled the measurement of transcriptional changes in genes involved in multiple biochemical pathways across the transition period, enabling a better understanding of the implications of management and nutritional changes on cow health and productivity. Most recent research efforts have focussed on the association between pre-calving energy intake and postpartum health and productivity, with a general recognition that the positive relationship between pre-calving energy intake (and relevant circulating metabolites) and postpartum health and productivity is, for the most part, not causative (i.e. responses are very likely to reflect the same metabolic perturbation, but one is not necessarily the cause of the other). This effect is consistent in both grazing systems and in systems where cows are fed total mixed ration in confinement. These results require a paradigm shift in the extension message to farmers. Because of the focus on energy nutrition, there has been only limited recent research on the requirements of cows for protein, with recommendations based largely on predicted requirements rather than measured responses. That said, metabolisable protein is unlikely to be a limiting nutrient for late-gestation dairy cows grazing up to 50% of their diet as high-protein forages, but could potentially be limiting prepartum mammary development in animals on lower-protein diets, such as total mixed rations formulated for dry cows. The physiological role of fatty acids, in addition to the role of fat as an energy source, is an emerging and important research area, with increasing evidence, at least in vitro, that specific fatty acids regulate metabolic processes. Knowledge gaps and future research areas that should be prioritised are identified and discussed.
Dry matter and nitrogen partitioning and translocation in winter oilseed rape (Brassica napus L.) grown under rainfed Mediterranean conditions
Authors: Papantoniou A. N. , Tsialtas J. T. , Papakosta D. K.
Published: May 2013

For crops grown in Mediterranean environments, translocation of pre-anthesis assimilates to the fruit is of great importance, because hot and dry conditions during fruit ripening diminish net assimilation rate and nitrogen (N) uptake. This field study was conducted to assess the pattern of dry matter and N accumulation and the role of assimilate translocation in pod development of oilseed rape plants in a Mediterranean environment. Four cultivars of winter oilseed rape (Brassica napus L.), i.e. three hybrids (Royal, Exact, Excalibur) and an inbred line (Fortis), were grown for two growing seasons (2005–06 and 2006–07) in northern Greece. On average, 581, 1247, 1609, and 2749 growing degree-days (GDD) were required for six leaves, stem elongation, 50% anthesis in main stem, and physiological maturity in the first year, and 539, 1085, 1601, and 2728 GDD in the second year. The R2 of the modified Richards function indicated that aboveground biomass and N accumulation were described with high approximation efficacy. The across-cultivars genotype mean maximum predicted total aboveground dry matter and N content were 1368.8 and 21.4 g m–2 in 2006 and 1655.1 and 25.4 g m–2 in 2007. In 2007, dry matter and N translocation from vegetative tissues to pods were 464.4 and 21.0 g m–2, and significantly higher than the corresponding values recorded in 2006 (264.4 and 17.0 g m–2). These differences were due to greater amounts of dry matter and N accumulating at anthesis and the greater sink capacity of plants (pod number) in 2007. The fact that pod development occurred in a period when N accumulation by oilseed rape plants had stopped led to high values of contribution of pre-anthesis N accumulation to pod N content in both years (92.8% in 2006 and 96.6% in 2007). Results indicated that hot and dry weather post anthesis reduced dramatically the net assimilation rates; thus, translocation of pre-anthesis assimilates was crucial for pod development. The results demonstrate that variation in weather conditions between growing seasons is one of the main causes of seasonal variation in oilseed rape productivity under Mediterranean conditions.
Tryptophan-mediated charge-resonance stabilization in the
bis
-Fe(IV) redox state of MauG
Authors: Geng Jiafeng , Dornevil Kednerlin , Davidson Victor L. , Liu Aimin
Published: May 2013

The diheme enzyme MauG catalyzes posttranslational modifications of a methylamine dehydrogenase precursor protein to generate a tryptophan tryptophylquinone cofactor. The MauG-catalyzed reaction proceeds via a
bis
-Fe(IV) intermediate in which one heme is present as Fe(IV)=O and the other as Fe(IV) with axial histidine and tyrosine ligation. Herein, a unique near-infrared absorption feature exhibited specifically in
bis
-Fe(IV) MauG is described, and evidence is presented that it results from a charge-resonance-transition phenomenon. As the two hemes are physically separated by 14.5 Å, a hole-hopping mechanism is proposed in which a tryptophan residue located between the hemes is reversibly oxidized and reduced to increase the effective electronic coupling element and enhance the rate of reversible electron transfer between the hemes in
bis
-Fe(IV) MauG. Analysis of the MauG structure reveals that electron transfer via this mechanism is rapid enough to enable a charge-resonance stabilization of the
bis
-Fe(IV) state without direct contact between the hemes. The finding of the charge-resonance-transition phenomenon explains why the
bis
-Fe(IV) intermediate is stabilized in MauG and does not permanently oxidize its own aromatic residues.
Afghanistan: transitional justice in the midst of war
Authors: Atashi Elham
Published: May 2013

In Afghanistan, there has been much talk about, and international support for dealing with past injustices by developing transitional justice mechanisms. Reconciliation is being promoted as a nation-building strategy. This article argues that the implementation of transitional justice poses several challenges. First, a significant component of such a strategy is based on reconciliation taking place internally among competing armed groups and ethnic identities with the goal of transforming Afghan society. This assumes the cause of past conflicts to be internal and along ethnic divisions which limits the accountability for war crimes. It also considers violence and crimes of war as a thing of the past, ignoring the present situation. Furthermore, given the ongoing war between the US-led forces and the Taliban, insecurity and escalating levels of violence one has to question whether transitional justice can take place during a war. This article concludes that transitional justice is interconnected to perceptions of security and stability. The analysis of the present situation in Afghanistan poses critical questions as to whether memories of victims can be considered as the past in the midst of war.