bluuebunny/crossref_metadata_2025 huggingface dataset:
Phytosterol Content and Fatty Acid Pattern of Ten Different Nut Types
Authors: Kornsteiner-Krenn Margit , Wagner Karl-Heinz , Elmadfa Ibrahim
Published: October 2014

Ten different nut kinds (almonds, Brazil nuts, cashews, hazelnuts, macadamias, peanuts, pecans, pine nuts, pistachios, and walnuts) were evaluated for their total oil and phytosterol content as well as their fatty acid composition. The total oil content was the predominant component; mean values oscillated between 45.2 % (cashews) and 74.7 % (macadamias). Mean total phytosterol content ranged from 71.7 mg (Brazil nuts) to 271.9 mg (pistachios) per 100 g oil. ß-sitosterol was the major sterol (mean >71.7 mg/100 g oil) followed by minor contents of campesterol, ergosterol, and stigmasterol. Almonds, cashews, hazelnuts, macadamias, and pistachios were high in monounsaturated fatty acids (MUFA; > 55 %). MUFA- and polyunsaturated fatty acid (PUFA)-rich nuts were peanuts and pecans, whereas Brazil nuts, pine nuts, and walnuts had the highest PUFA content (> 50 %); the high unsaturated/saturated fatty acid ratio ranged from 4.5 to 11.8. However, the fatty acid pattern of every nut is unique.
Phyllanthus emblica L. Fruit Extract Induces Chromosomal Instability and Suppresses Necrosis in Human Colon Cancer Cells
Authors: Guo Xihan , Ni Juan , Liu Xuemin , Xue Jinglun , Wang Xu
Published: October 2014

Phyllanthus emblica L. (PE) is an edible fruit indigenous to Southeast Asia. It has been considered as a potent functional food due to its numerous pharmacological applications, such as anti-oxidant, antimicrobial, anti-diabetic and protection for multiple organs. The aim of this study was to evaluate the effects of a water extract of PE fruit on genomic damage and cell death in the human colon adenocarcinoma cell line COLO320 using the cytokinesis-block micronucleus cytome assay. Cells were exposed to RPMI-1640 medium containing 0, 20, 40, 80, or 160 μg/mL PE for 24, 48, 72, or 96 hours. The results showed that PE induced a significant decrease in necrosis (p < 0.001) and nuclear division index (NDI) (p < 0.001) in a dose- and time-dependent manner, and there was a highly significant correlation between the reduction of necrosis and NDI (r = 0.820, p < 0.001). Dose- and time-dependent increases (p < 0.001) in the frequency of chromosomal instability (CIN) were observed after PE exposure, and the frequency of CIN was negatively correlated with NDI (r = - 0.640, p < 0.001). PE also significantly increased apoptosis (p < 0.001), and there was a significant correlation of apoptosis with CIN (r = 0.566, p < 0.001). In conclusion, PE suppresses necrosis and delays mitotic progression, which results in massive CIN followed by apoptosis in COLO320 cells.
Riboflavin Supplementation to Patients with Multiple Sclerosis does not Improve Disability Status nor is Riboflavin Supplementation Correlated to Homocysteine
Authors: Naghashpour Mahshid , Majdinasab Nastaran , Shakerinejad Ghodratollah , Kouchak Maryam , Haghighizadeh Mohammad H. , Jarvandi Farzaneh , Hajinajaf Saideh
Published: October 2014

Background: Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system. Riboflavin is involved in myelin formation in nerve cells. Riboflavin is a precursor of flavin adenine D-nucleotide (FAD), which is a coenzyme of methylene tetrahydrofolate reductase (MTHFR), which is an important enzyme for remethylation of homocysteine. Riboflavin supplementation has been shown to affect the serum levels of homocysteine in healthy volunteers. The aim of the present study was to test the effect of riboflavin supplementation on the status and disability of patients with MS and whether this effect could be mediated by serum homocysteine levels. Materials and Methods: This was a randomized, double-blind, controlled trial in which 29 MS patients with a mean age of 33 were tested with riboflavin, and the placebo group, with a mean age of 31, received either riboflavin supplementation (10 mg) or the placebo daily for six months. Disability, measured by the Expanded Disability Status Scale (EDSS) scores, erythrocyte glutathione reductase activity coefficient (EGRAC), and serum homocysteine levels were measured before and after the study. Results: The mean ± SD of EDSS score was significantly decreased in both groups over the six months of the study (2.3 ± 0.7 vs. 1.6 ± 0.6 for the riboflavin group and 2.8 ± 1.1 vs. 2.3 ± 1.3 for the placebo groups. The comparison across both groups yielded a non-significant change (P = 0.001 and 0.02, respectively). No significant differences were observed between the two groups in terms of EGRAC, riboflavin deficiency levels by EGRAC category, and serum homocysteine levels before and after the study. Conclusion: Riboflavin supplementation (10 mg/day) to patients with MS does not improve disability status. It appears that this effect is not related to serum homocysteine levels.
Association Between Dietary Vitamin C and Risk of Cutaneous Melanoma in a Population of Northern Italy
Authors: Malavolti Marcella , Malagoli Carlotta , Fiorentini Chiara , Longo Caterina , Farnetani Francesca , Ricci Cinzia , Albertini Giuseppe , Lanzoni Anna , Reggiani Camilla , Virgili Annarosa , Pagliarello Calogero , Santini Marcello , Fanti Pier A. , Dika Emi , Sieri Sabina , Krogh Vittorio , Pellacani Giovanni , Vinceti Marco
Published: October 2014

Cutaneous melanoma incidence has been increasing during the last few years, and diet has been suggested as one of the lifestyle factors responsible for this increase. Since antioxidant nutrients such as ascorbic acid might prevent skin carcinogenesis, we investigated the risk of cutaneous melanoma related to vitamin C intake in a population-based case-control study in Northern Italy based on 380 melanoma patients and 719 matched controls, to whom we administered a semiquantitative food-frequency questionnaire. After adjusting for potential confounders, odds ratio of melanoma were 0.86 (95 % confidence interval 0.65 - 1.15) and 0.59 (95 % confidence interval 0.37 - 0.94) in the intermediate and highest categories of vitamin C dietary intake respectively, compared with the bottom one. The association between vitamin C and decreased risk persisted after adjustment for some potential confounders. In age- and gender-stratified analyses, this association was seen in young females (< 60 years old), and was found to be enhanced in subjects with phototypes II and III. These results suggest a possible protective activity of vitamin C intake against cutaneous melanoma in specific subgroups of this population of Northern Italy.
Differences in Vitamin E and C Profile Between Infant Formula and Human Milk and Relative Susceptibility to Lipid Oxidation
Authors: Elisia Ingrid , Kitts David D.
Published: October 2014

The vitamin E isoforms and vitamin (vit) C content of infant formulas were compared to human milk and related to relative susceptibilities to lipid peroxidation. We report that a highly distinct vitamin E and C profile exists between formula and human milk. Whileα-tocopherol (α-Toc) is the dominant vit E isoform in human milk, formula contains a substantial amount of α-Toc and δ-Toc that was greater than the level found in human milk (12- and 32-fold, respectively). Vitamin C was also two- fold higher in infant formula compared to human milk. Despite the higher vitamin E and C content, we also observed higher rates of lipid oxidation in the formula when compared to human milk. Storing human milk for one day at refrigeration temperatures did not produce hexanal in human milk, but this storage resulted in an increase in hexanal in formulas. We conclude that the higher concentrations of γ-Toc and δ-Toc in infant formulas did not provide similar protection from lipid oxidation as human milk. We also observed that vit C content was reduced during storage in both infant formula and human milk, which did not occur with the Toc isoforms.
Diagnostische Kompetenzen von Mathematiklehrern und ihr Vorhersagewert für die Lernentwicklung von Grundschulkindern
Authors: Karst Karina , Schoreit Edgar , Lipowsky Frank
Published: October 2014

Dieser Beitrag prüft, wie drei Ebenen diagnostischer Kompetenzen (klassenbezogene, schülerglobale und schülerspezifische DK) die Lernentwicklung von Grundschulkindern im Fach Mathematik beeinflussen. Dabei werden theoretisch wie psychometrisch die Ansätze von Karst (2012) und Schrader (1989) verfolgt. Die Stichprobe umfasst 680 Schüler, die am Ende der ersten (t1) und am Ender der zweiten (t2) Klasse in ihren arithmetischen Kompetenzen getestet wurden. Zudem schätzten 32 Lehrkräfte die Testleistung ihrer Schüler ein (t1). Mehrebenenanalysen zeigen, dass die klassenbezogene DK die Lernentwicklung positiv vorhersagt, während die DK, bei der die Lehrkraft einzelne Schüler in Lernbereichen einschätzt (schülerglobale DK und Rangkomponente), die Lernentwicklung negativ prädiziert. Die schülerspezifische DK zeigt keine empirische Relevanz. Dabei sind hohe Varianzüberlappungen zwischen den Kennwerten nach Schrader (1989) und dem jeweiligen Kennwert nach Karst (2012) festzustellen. Die teilweise erwartungswidrigen Befunde werfen die Frage auf, ob mit einer Zunahme diagnostischer Kompetenzen unbedingt eine Verbesserung der Unterrichtsqualität und damit der Lernentwicklung einhergehen muss.
Effekte der kontextuellen Einkleidung von Testaufgaben auf die Schülerleistungen im analytischen Problemlösen und in der Mathematik
Authors: Fleischer Jens , Wirth Joachim , Leutner Detlev
Published: October 2014

Ergebnisse aus PISA 2003 zeigen für Deutschland eine Diskrepanz zwischen der im internationalen Vergleich hohen Problemlösekompetenz und der durchschnittlichen Mathematikkompetenz. Nach der Potenzialnutzungshypothese kann dies teilweise auf eine mangelnde Nutzung vorhandener Fachkompetenzen während der Testbearbeitung zurückgeführt werden. Der vorliegende Beitrag geht dieser Hypothese im Rahmen von zwei experimentellen Studien nach. Hierbei wurden Effekte der kontextuellen Einkleidung von Mathematikaufgaben (Studie 1, n = 256) und Problemlöseaufgaben (Studie 2, n = 259) auf Schülerleistungen untersucht sowie Moderationseffekte durch das mathematische Selbstkonzept und die Mathematikangst überprüft. In beiden Studien zeigten sich negative Effekte der mathematischen Kontexteinkleidung, insbesondere bei Lernenden mit geringem mathematischem Selbstkonzept sowie bei Lernenden mit hoher Mathematikangst. Implikationen der Ergebnisse für die Erfassung sowie die Förderung domänenübergreifender und domänenspezifischer Problemlösekompetenzen werden diskutiert.
Komplexes Problemlösen im Fach Chemie: Ein domänenspezifischer Zugang
Authors: Scherer Ronny
Published: October 2014

In der vorliegenden Studie wird ein theoretisches Kompetenzmodell für das Fach Chemie vorgestellt, das domänenübergreifende und domänenspezifische Konzeptualisierungen komplexer Problemlösekompetenz verbindet. Hierbei werden vier Teilkompetenzen angenommen, die Verstehens-, Repräsentations-, Lösungs- und Reflexionsprozesse umfassen. In einer Untersuchung mit N = 981 Schülerinnen und Schülern der zehnten und zwölften Jahrgangsstufe wurde das Modell geprüft. Mit Methoden der Item-Response-Theorie konnte gezeigt werden, dass ein vierdimensionales Partial-Credit-Modell die Struktur der Problemlösekompetenz abbildet. Darüberhinaus wurde Messinvarianz über die beiden Jahrgangsstufen nachgewiesen. Kompetenzniveauunterschiede bestehen am Übergang in die gymnasiale Oberstufe für zwei der vier Teilkompetenzen zugunsten der Sekundarstufe II. Problemlösekompetenz korrelierte mit Reasoning, dem Fach- und Strategiewissen sowie der Chemienote. Somit werden verschiedene Facetten der Konstruktvalidität aufgezeigt sowie die Bedeutung einer domänenspezifischen Erfassung komplexer Problemlösekompetenz diskutiert.
Komplexes Problemlösen, schulfachliche Kompetenzen und ihre Relation zu Schulnoten
Authors: Kretzschmar André , Neubert Jonas C. , Greiff Samuel
Published: October 2014

Die Bedeutung des komplexen Problemlösens (KPL) hat sich im pädagogisch-psychologischen Kontext vielfach gezeigt und ist einer der Gründe dafür, dass KPL in Schulleistungsstudien (z. B. PISA) eine wichtige Rolle einnimmt. Bisherige Forschungsarbeiten zum Einfluss von KPL auf Schulleistungen haben jedoch schulfachliche Kompetenzen und deren Beziehung zu Schulnoten außer Acht gelassen. Diese Forschungslücke soll mit der vorliegenden Arbeit geschlossen werden, indem die Beziehung zwischen KPL und schulfachspezifischen Kompetenzen in Mathematik sowie Lesen untersucht wurde. An einer finnischen Stichprobe mit N = 1908 Schülerinnen und Schülern wurde mittels Strukturgleichungsmodellen der Zusammenhang zwischen KPL, schulfachlichen Kompetenzen sowie fachspezifischen Schulnoten überprüft. Die Ergebnisse zeigten, dass KPL über die schulfachlichen Kompetenzen hinaus inkrementell Varianz der Schulnoten in Mathematik und muttersprachlichem Unterricht aufklären konnte. Dies zeigte sich deutlicher für das mathematische als für das muttersprachliche Schulfach, insbesondere wenn für schlussfolgerndes Denken kontrolliert wurde. Implikationen für das Verständnis von KPL und dessen Bedeutung im pädagogisch-psychologischen Kontext werden diskutiert.
Zeitökonomische und reliable Diagnostik beruflicher Problemlösekompetenzen bei Auszubildenden zum Kfz-Mechatroniker
Authors: Abele Stephan , Walker Felix , Nickolaus Reinhold
Published: October 2014

Im vorliegenden Beitrag wird eine bislang ungelöste Herausforderung bei der Erfassung beruflicher Problemlösekompetenzen behandelt: Aufgrund langer Bearbeitungszeiten ökologisch valider beruflicher Problemlöse-Szenarien und begrenzter Testzeiten können zur Diagnostik nur wenige Szenarien vorgegeben werden. Das damit verbundene Reliabilitätsproblem wird am Beispiel von Kfz-Mechatronikern des 3. Ausbildungsjahrs (N = 275) bearbeitet, deren Problemlösekompetenz sich insbesondere bei der Kfz-Fehlerdiagnose zeigt. Vorgestellt wird ein diagnostischer Ansatz, bei dem Kfz-Fehlerdiagnose-Szenarien und Teilkompetenz(TK)-Items eingesetzt werden, die relativ schnell zu bearbeiten sind und leistungskritische Anforderungen der Kfz-Fehlerdiagnose abdecken. Die Ergebnisse zeigen, dass die TK-Items und die Fehlerdiagnose-Szenarien eindimensional modellierbar sind und der ergänzende Einsatz der TK-Items zeitökonomisch einen substantiellen Reliabilitätszuwachs bringt. Abschließend wird diskutiert, ob der Ansatz auf andere Domänen übertragbar ist und pädagogische Interventionen bereichern kann.
Pädagogisch-Psychologische Problemlöseforschung als Problem – Barrieren überwinden
Authors: Kröner Stephan
Published: October 2014

Problemlöseforschung hat nicht nur unterschiedliche Problemstellungen zum Gegenstand, sondern kann ihrerseits als Problemlösehandlung verstanden werden. Vor diesem Hintergrund werden zunächst Ziel und Gegenstand pädagogisch-psychologischer Problemlöseforschung skizziert, und es wird erörtert, welche Barrieren für deren Erreichung zu überwinden sind. In der Folge werden die Beiträge des aktuellen Themenschwerpunkts herangezogen, um den Ausgangszustand und die bislang in der Problemlöseforschung eingesetzten Methoden zu analysieren. Abschließend wird diskutiert, welche nächsten Schritte zur Überwindung verbleibender Barrieren beitragen könnten.
Problemlösen in der Pädagogischen Psychologie
Authors: Greiff Samuel , Kretzschmar André , Leutner Detlev
Published: October 2014

Problemlösen wird als eine zentrale Kompetenz angesehen, um in einer komplexer werdenden und sich schnell verändernden Welt erfolgreich zu sein. So ist es nicht verwunderlich, dass Problemlösen in jüngerer Zeit besonders in der pädagogisch-psychologischen Forschung an Bedeutung gewonnen hat. Dieser Entwicklung Rechnung tragend, gibt das vorliegende Editorial zum Themenschwerpunkt «Problemlösen in der Pädagogischen Psychologie» zunächst einen Überblick über die verschiedenen Konzeptionen des Problemlösens sowie aktuellen Forschungsfragen, bevor die einzelnen Beiträge dieses Themenschwerpunktes vorgestellt werden. Ziel ist dabei, einerseits die Breite der bisherigen Forschung sowie aktuelle Entwicklungen zum Problemlösen im pädagogisch-psychologischen Kontext integrierend darzustellen, andererseits aber auch das Potential für zukünftige Forschungsanliegen konkret herauszuarbeiten.
Ein WHO Konzept – Patient Blood Management
Authors: Theusinger Oliver M.
Published: October 2014

Bluttransfusionen gelten in der Regel als eine möglicherweise lebensrettende Massnahme. Die aktuelle Datenlage zeigt jedoch, dass Transfusionen und das mittlerweile mengenabhängig, mit einer deutlich erhöhten Morbidität und Mortalität assoziiert sind. Neben verschiedenen Erklärungsversuchen aus der Grundlagenforschung, legen seit neuestem Ergebnisse kontrollierter randomisierter Studien klar dar, dass von einem kausalen Zusammenhang auszugehen ist. Aufgrund dessen ist die Meinung und Idee der lebensrettenden Bluttransfusion kritischer zu sehen, da diese Intervention auf eine deutlich lebensbedrohende und krankheitsfördernde Wirkung hinweist. Zusätzlich dazu sind Transfusionen mit deutlich höheren Kosten verbunden als bisher angenommen. Somit sind bei Anämie und Blutungen neue Behandlungskonzepte im Sinne von «patient blood management» (PBM) dringend notwendig. PBM senkt die Transfusionsrate durch Anämiekorrektur mithilfe stimulierter Erythropoese, Minimierung des perioperativen Blutverlustes und Erhöhung der physiologischen Anämietoleranz. In einer Resolution der World Health Organisation (WHO) 2010 wird PBM als Behandlungsstandard gefordert. Durch Reduktion des überhöhten Blutverbrauchs können Morbidität und Mortalität deutlich reduziert werden. In der Uniklinik Balgrist in Zürich wurde dieses Konzept nun teilweise eingeführt und zeigt deutliche Erfolge.
Transkutane Applikationen bei Impfungen und Immuntherapien
Authors: Krämer Isabel , Zabel Franziska , Kündig Thomas M. , Johansen Pål
Published: October 2014

Obwohl Edward Jenner die Haut nutzte, um die ersten Impfungen zu applizieren, sind die immunologischen Eigenschaften der Haut erst in den letzten 20 Jahren so richtig verstanden worden. Die Haut eignet sich speziell für transkutane Impfungen und Immuntherapien, da sich in der Epidermis und der Dermis eine hohe Dichte kompetenter Immunzellen befindet. In der medizinischen Forschung gibt es verschiedene Ansätze für transkutane Verabreichungsformen. Man unterscheidet zwischen chemischen, biochemischen und physikalischen Methoden, um mit grösseren Molekülen in die Haut zu gelangen. Vor allem für Kinder würden sich die schmerzfreien Therapien eignen, aber auch für Erwachsene ist diese, in der Regel von Patienten selber applizierte, nicht-invasive Verabreichungsmethode eine attraktive Alternative zu den herkömmlichen Injektionsmethoden. Zukünftige Produkte befinden sich in Studien der Phase I-III und liefern vielversprechende Ergebnisse.
Klinische Bedeutung der Aktivierung der Rumpfmuskelketten während Rumpfübungen – eine systematische Literaturübersicht
Authors: Rogan Slavko , Riesen Jan , Taeymans Jan
Published: October 2014

Eine gut funktionierende Rumpfmuskulatur ist zur Bewältigung von täglichen Aktivitäten für den Menschen unverzichtbar. Für einen Athleten ist es ein wichtiger Faktor für sportlichen Erfolg. In der Literatur ist jedoch nicht genau beschrieben, inwiefern die Rumpfmuskulatur durch Übungen effektiver angesteuert werden kann. Das Ziel dieser systematischen Literaturstudie war es, die Aktivierungsrate, gemessen mittels Elektromyographie, der ventralen, lateralen und dorsalen Rumpfmuskelketten während der Ausführung von Rumpfmuskelübungen zu evaluieren. Es erfolgte eine systematische Literatursuche in Pedro, PubMed, Medpilot und Embase. Es wurden 16 Studien eingeschlossen. Alle untersuchten Übungsvarianten erreichten eine gute Aktivierungsrate der Rumpfmuskulatur. Die Ausgangsstellung beeinflusste tendenziell das Aktivierungsmass der Rumpfmuskulatur: Übungen aus einer vertikalen Ausgangsstellung («Deadlift» oder «Squats») aktivierten die Rumpfmuskulatur signifikant stärker als Übungen in einer horizontalen Ausgangsstellung.
Therapierefraktäre Pneumonie
Authors: Oestmann Andreas , Schäfer Stephan Christian , Geiser Thomas
Published: October 2014

Wir berichten über eine 72-jährige Patientin mit B-Symptomatik und einem persistierenden pulmonalen Infiltrat trotz antibiotischer Behandlung. In der transbronchialen Biopsie fand sich intraalveoläres Granulationsgewebe vereinbar mit einer organisierenden Pneumonie. Eine Steroid-Therapie führte zu einer prompten Besserung der B-Symptomatik sowie zu einer Regredienz des Infiltrates. Auch wenn aufgrund einer chronisch-lymphatischen Leukämie (CLL) sowie einer vier Monate früher behandelten Pneumonie eine mögliche Ursache für eine sekundär organisierende Pneumonie vorlag, handelte es sich am ehesten trotzdem um eine kryptogen organisierende Pneumonie (COP).
Inter-phylum HGT has shaped the metabolism of many mesophilic and anaerobic bacteria
Authors: Caro-Quintero Alejandro , Konstantinidis Konstantinos T
Published: October 2014

Genome sequencing has revealed that horizontal gene transfer (HGT) is a major evolutionary process in bacteria. Although it is generally assumed that closely related organisms engage in genetic exchange more frequently than distantly related ones, the frequency of HGT among distantly related organisms and the effect of ecological relatedness on the frequency has not been rigorously assessed. Here, we devised a novel bioinformatic pipeline, which minimized the effect of over-representation of specific taxa in the available databases and other limitations of homology-based approaches by analyzing genomes in standardized triplets, to quantify gene exchange between bacterial genomes representing different phyla. Our analysis revealed the existence of networks of genetic exchange between organisms with overlapping ecological niches, with mesophilic anaerobic organisms showing the highest frequency of exchange and engaging in HGT twice as frequently as their aerobic counterparts. Examination of individual cases suggested that inter-phylum HGT is more pronounced than previously thought, affecting up to ∼16% of the total genes and ∼35% of the metabolic genes in some genomes (conservative estimation). In contrast, ribosomal and other universal protein-coding genes were subjected to HGT at least 150 times less frequently than genes encoding the most promiscuous metabolic functions (for example, various dehydrogenases and ABC transport systems), suggesting that the species tree based on the former genes may be reliable. These results indicated that the metabolic diversity of microbial communities within most habitats has been largely assembled from preexisting genetic diversity through HGT and that HGT accounts for the functional redundancy among phyla.
DNAzyme-based biosensors and nanodevices
Authors: Gong Liang , Zhao Zilong , Lv Yi-Fan , Huan Shuang-Yan , Fu Ting , Zhang Xiao-Bing , Shen Guo-Li , Yu Ru-Qin
Published: October 2014

DNAzymes, screened throughin vitroselection, have shown great promise as molecular tools in the design of biosensors and nanodevices.
Hybrid CuO/SnO2 nanocomposites: Towards cost-effective and high performance binder free lithium ion batteries anode materials
Authors: Xing G. Z. , Wang Y. , Wong J. I. , Shi Y. M. , Huang Z. X. , Li S. , Yang H. Y.
Published: October 2014

Hybrid CuO/SnO2 nanocomposites are synthesized by a facile thermal annealing method on Cu foils. Compared to pristine CuO and SnO2 nanostructures, hybrid CuO/SnO2 nanocomposites exhibit the enhanced electrochemical performances as the anode material of lithium ion batteries (LIBs) with high specific capacity and excellent rate capability. The binder free CuO/SnO2 nanocomposites deliver a specific capacity of 718 mA h g−1 at a current density of 500 mA g−1 even after 200 cycles. The enhanced electrochemical performances are attributed to the synergistic effect between SnO2 nanoparticles and CuO nanoarchitectures. Such hybrid CuO/SnO2 nanocomposites could open up a new route for the development of next-generation high-performance and cost-effective binder free anode material of LIBs for mass production.
High temperature dielectric relaxation anomaly of Y3+ and Mn2+ doped barium strontium titanate ceramics
Authors: Yan Shiguang , Mao Chaoliang , Wang Genshui , Yao Chunhua , Cao Fei , Dong Xianlin
Published: October 2014

Relaxation like dielectric anomaly is observed in Y3+ and Mn2+ doped barium strontium titanate ceramics when the temperature is over 450 K. Apart from the conventional dielectric relaxation analysis method with Debye or modified Debye equations, which is hard to give exact temperature dependence of the relaxation process, dielectric response in the form of complex impedance, assisted with Cole-Cole impedance model corrected equivalent circuits, is adopted to solve this problem and chase the polarization mechanism in this paper. Through this method, an excellent description to temperature dependence of the dielectric relaxation anomaly and its dominated factors are achieved. Further analysis reveals that the exponential decay of the Cole distribution parameter n with temperature is confirmed to be induced by the microscopic lattice distortion due to ions doping and the interaction between the defects. At last, a clear sight to polarization mechanism containing both the intrinsic dipolar polarization and extrinsic distributed oxygen vacancies hopping response under different temperature is obtained.
Partial molar enthalpies and reaction enthalpies from equilibrium molecular dynamics simulation
Authors: Schnell Sondre K. , Skorpa Ragnhild , Bedeaux Dick , Kjelstrup Signe , Vlugt Thijs J. H. , Simon Jean-Marc
Published: October 2014

We present a new molecular simulation technique for determining partial molar enthalpies in mixtures of gases and liquids from single simulations, without relying on particle insertions, deletions, or identity changes. The method can also be applied to systems with chemical reactions. We demonstrate our method for binary mixtures of Weeks-Chandler-Anderson particles by comparing with conventional simulation techniques, as well as for a simple model that mimics a chemical reaction. The method considers small subsystems inside a large reservoir (i.e., the simulation box), and uses the construction of Hill to compute properties in the thermodynamic limit from small-scale fluctuations. Results obtained with the new method are in excellent agreement with those from previous methods. Especially for modeling chemical reactions, our method can be a valuable tool for determining reaction enthalpies directly from a single MD simulation.
Nature of the effective interaction between dendrimers
Authors: Mandal Taraknath , Dasgupta Chandan , Maiti Prabal K.
Published: October 2014

We have performed fully atomistic classical molecular dynamics simulations to calculate the effective interaction between two polyamidoamine dendrimers. Using the umbrella sampling technique, we have obtained the potential of mean force (PMF) between the dendrimers and investigated the effects of protonation level and dendrimer size on the PMF. Our results show that the interaction between the dendrimers can be tuned from purely repulsive to partly attractive by changing the protonation level. The PMF profiles are well-fitted by the sum of an exponential and a Gaussian function with the weight of the exponential function dominating over that of the Gaussian function. This observation is in disagreement with the results obtained in previous analytic [C. Likos, M. Schmidt, H. Löwen, M. Ballauff, D. Pötschke, and P. Lindner, Macromolecules 34, 2914 (2001)] and coarse-grained simulation [I. Götze, H. Harreis, and C. Likos, J. Chem. Phys. 120, 7761 (2004)] studies which predicted the effective interaction to be Gaussian.
A compact proton spectrometer for measurement of the absolute DD proton spectrum from which yield and ρR are determined in thin-shell inertial-confinement-fusion implosions
Authors: Rosenberg M. J. , Zylstra A. B. , Frenje J. A. , Rinderknecht H. G. , Gatu Johnson M. , Waugh C. J. , Séguin F. H. , Sio H. , Sinenian N. , Li C. K. , Petrasso R. D. , Glebov V. Yu. , Hohenberger M. , Stoeckl C. , Sangster T. C. , Yeamans C. B. , LePape S. , Mackinnon A. J. , Bionta R. M. , Talison B. , Casey D. T. , Landen O. L. , Moran M. J. , Zacharias R. A. , Kilkenny J. D. , Nikroo A.
Published: October 2014

A compact, step range filter proton spectrometer has been developed for the measurement of the absolute DD proton spectrum, from which yield and areal density (ρR) are inferred for deuterium-filled thin-shell inertial confinement fusion implosions. This spectrometer, which is based on tantalum step-range filters, is sensitive to protons in the energy range 1-9 MeV and can be used to measure proton spectra at mean energies of ∼1-3 MeV. It has been developed and implemented using a linear accelerator and applied to experiments at the OMEGA laser facility and the National Ignition Facility (NIF). Modeling of the proton slowing in the filters is necessary to construct the spectrum, and the yield and energy uncertainties are ±<10% in yield and ±120 keV, respectively. This spectrometer can be used for in situ calibration of DD-neutron yield diagnostics at the NIF.
Hierarchical mesoporous/microporous carbon with graphitized frameworks for high-performance lithium-ion batteries
Authors: Lv Yingying , Wu Zhangxiong , Fang Yin , Qian Xufang , Asiri Abdullah M. , Tu Bo , Zhao Dongyuan
Published: October 2014

A hierarchical meso-/micro-porous graphitized carbon with uniform mesopores and ordered micropores, graphitized frameworks, and extra-high surface area of ∼2200 m2/g, was successfully synthesized through a simple one-step chemical vapor deposition process. The commercial mesoporous zeolite Y was utilized as a meso-/ micro-porous template, and the small-molecule methane was employed as a carbon precursor. The as-prepared hierarchical meso-/micro-porous carbons have homogeneously distributed mesopores as a host for electrolyte, which facilitate Li+ ions transport to the large-area micropores, resulting a high reversible lithium ion storage of 1000 mA h/g and a high columbic efficiency of 65% at the first cycle.
How far do electrons delocalize?
Authors: Janesko Benjamin G. , Scalmani Giovanni , Frisch Michael J.
Published: October 2014

Electron delocalization is central to chemical bonding, but it is also a fundamentally nonclassical and nonintuitive quantum mechanical phenomenon. Tools to quantify and visualize electron delocalization help to understand, teach, and predict chemical reactivity. We develop a new approach to quantify and visualize electron delocalization in real space. Our electron delocalization range function \documentclass[12pt]{minimal}\begin{document}${\textrm {EDR}}({\vec{r}};u)$\end{document} EDR (r⃗;u) quantifies the degree to which electrons at point \documentclass[12pt]{minimal}\begin{document}${\vec{r}}$\end{document}r⃗ in a calculated wavefunction delocalize over length scale u. Its predictions are physically reasonable. For example, \documentclass[12pt]{minimal}\begin{document}${\textrm {EDR}}({\vec{r}};u=0.25\ {\textrm {bohr}})$\end{document} EDR (r⃗;u=0.25 bohr ) is close to one at points \documentclass[12pt]{minimal}\begin{document}${\vec{r}}$\end{document}r⃗ in the cores of first-row atoms, consistent with the localization of core electrons to ∼0.25 bohr. \documentclass[12pt]{minimal}\begin{document}${\textrm {EDR}}({\vec{r}};u=1\ {\textrm {bohr}})$\end{document} EDR (r⃗;u=1 bohr ) is close to one at points \documentclass[12pt]{minimal}\begin{document}${\vec{r}}$\end{document}r⃗ in typical covalent bonds, consistent with electrons delocalizing over the length of the bond. Our approach provides a rich representation of atomic shell structure; covalent and ionic bonding; the delocalization of excited states, defects, and solvated electrons; metallic and insulating systems; and bond stretching and strong correlation.
Equivalence of two independent calculations of the higher order guiding center Lagrangian
Authors: Parra F. I. , Calvo I. , Burby J. W. , Squire J. , Qin H.
Published: October 2014

The difference between the guiding center phase-space Lagrangians derived in J. W. Burby et al. [Phys. Plasmas 20, 072105 (2013)] and F. I. Parra and I. Calvo [Plasma Phys. Controlled Fusion 53, 045001 (2011)] is due to a different definition of the guiding center coordinates. In this brief communication, the difference between the guiding center coordinates is calculated explicitly.
Adiabatic electron response and solitary wave generation by trapped particle nonlinearity in a hydrogen plasma
Authors: Mandal Debraj , Sharma Devendra
Published: October 2014

The finite amplitude ion acoustic waves that trap electrons modify the structure of the evolving nonlinear soliton solutions. In the numerical simulations, self-consistently generated solitary waves are studied that emerge as a result of a current driven microinstability growing the ion acoustic mode in a collisionless Vlasov plasma. The growth saturates as a result of nonlinear effects governed by a combination of nonlinearities originating from the hydrodynamic model and kinetic particle trapping effects. The resulting solitary waves also coexist with a finite current and an electron plasma wave capable of perturbing the trapping potential. The results of multiscale simulation are analyzed and characterized following the kinetic prescription of undamped trapped particle mode in the form of phase space vortex solutions that are generalized form of Sagdeev's solitons and obey the solutions of a modified Korteweg-de Vries equation, accounting for a stronger nonlinearity originating from the electron trapping.
Ion temperature in plasmas with intrinsic Alfven waves
Authors: Wu C. S. , Yoon P. H. , Wang C. B.
Published: October 2014

This Brief Communication clarifies the physics of non-resonant heating of protons by low-frequency Alfvenic turbulence. On the basis of general definition for wave energy density in plasmas, it is shown that the wave magnetic field energy is equivalent to the kinetic energy density of the ions, whose motion is induced by the wave magnetic field, thus providing a self-consistent description of the non-resonant heating by Alfvenic turbulence. Although the study is motivated by the research on the solar corona, the present discussion is only concerned with the plasma physics of the heating process.
Tungsten polyoxometalate molecules as active nodes for dynamic carrier exchange in hybrid molecular/semiconductor capacitors
Authors: Balliou A. , Douvas A. M. , Normand P. , Tsikritzis D. , Kennou S. , Argitis P. , Glezos N.
Published: October 2014

In this work we study the utilization of molecular transition metal oxides known as polyoxometalates (POMs), in particular the Keggin structure anions of the formula PW12O403−, as active nodes for potential switching and/or fast writing memory applications. The active molecules are being integrated in hybrid Metal-Insulator/POM molecules-Semiconductor capacitors, which serve as prototypes allowing investigation of critical performance characteristics towards the design of more sophisticated devices. The charging ability as well as the electronic structure of the molecular layer is probed by means of electrical characterization, namely, capacitance-voltage and current-voltage measurements, as well as transient capacitance measurements, C (t), under step voltage polarization. It is argued that the transient current peaks observed are manifestations of dynamic carrier exchange between the gate electrode and specific molecular levels, while the transient C (t) curves under conditions of molecular charging can supply information for the rate of change of the charge that is being trapped and de-trapped within the molecular layer. Structural characterization via surface and cross sectional scanning electron microscopy as well as atomic force microscopy, spectroscopic ellipsometry, UV and Fourier-transform IR spectroscopies, UPS, and XPS contribute to the extraction of accurate electronic structure characteristics and open the path for the design of new devices with on-demand tuning of their interfacial properties via the controlled preparation of the POM layer.
Analyzing a steady-state phenomenon using an ensemble of sequential transient events: A proof of concept on photocurrent of bacteriorhodopsin upon continuous photoexcitation
Authors: Hung Chang-Wei , Ho Ching-Hwa , Chu Li-Kang
Published: October 2014

The proton pump activity of bacteriorhodopsin in aqueous solution upon excitation with modulated continuous light was monitored electrochemically and analyzed by superimposing a series of transient proton translocation events Hi+(t). An evolution function f(t)=he−lt+kh+k, including a decay and a stationary offset, was introduced to weight the contribution of the individual transient events evolving with time in the envelope of the steady-state event. The evolution of the total proton concentration can be treated as an ensemble of weighted sequential transient events, Htotal+(t)=∑i=0nHi+(t)⋅f(t), and the temporal profile of the photocurrent is derived by differentiating the proton concentration with respect to time, I(t)∝dHtotal+(t)dt. The temporal profiles of the bacteriorhodopsin photocurrent in pH range of 6.3–8.1 were analyzed using a well-defined kinetics model and restricted mathematical formulization, and fitted temporal behaviors agreed with the observations. This successful proof-of-concept study on analyzing a steady-state phenomenon using an ensemble of sequential transient events can be generalized to quantify other phenomena upon continuous stimulation, such as estimation of the light-driven ion pump activities of the photosynthetic proteins upon illumination.
An orthogonal return method for linearly polarized beam based on the Faraday effect and its application in interferometer
Authors: Chen Benyong , Zhang Enzheng , Yan Liping , Liu Yanna
Published: October 2014

Correct return of the measuring beam is essential for laser interferometers to carry out measurement. In the actual situation, because the measured object inevitably rotates or laterally moves, not only the measurement accuracy will decrease, or even the measurement will be impossibly performed. To solve this problem, a novel orthogonal return method for linearly polarized beam based on the Faraday effect is presented. The orthogonal return of incident linearly polarized beam is realized by using a Faraday rotator with the rotational angle of 45°. The optical configuration of the method is designed and analyzed in detail. To verify its practicability in polarization interferometry, a laser heterodyne interferometer based on this method was constructed and precision displacement measurement experiments were performed. These results show that the advantage of the method is that the correct return of the incident measuring beam is ensured when large lateral displacement or angular rotation of the measured object occurs and then the implementation of interferometric measurement can be ensured.
Low precessional damping observed for L1-ordered FePd epitaxial thin films with large perpendicular magnetic anisotropy
Authors: Iihama S. , Sakuma A. , Naganuma H. , Oogane M. , Miyazaki T. , Mizukami S. , Ando Y.
Published: October 2014

High-quality L10 ordered 20 nm-thick FePd epitaxial thin films with a large perpendicular magnetic anisotropy were fabricated using a SrTiO3 substrate. The uniaxial crystalline magnetic anisotropy constant Ku evaluated for the films annealed above 500 °C was 14 Merg/cm3. A very low effective damping constant, αeff = 0.007, was observed for FePd thin films annealed at 500 °C. This value is smaller than that of other Fe-based ordered alloys with a large perpendicular magnetic anisotropy.
Shock response of magnesium single crystals at normal and elevated temperatures
Authors: Kanel G. I. , Garkushin G. V. , Savinykh A. S. , Razorenov S. V. , de Resseguier T. , Proud W. G. , Tyutin M. R.
Published: October 2014

A series of magnesium single crystals, from 0.2 to 3 mm thick, were shock loaded in directions parallel and perpendicular to the c-axis of the hexagonal closed packed (hcp) structure and at 45° to the c-axis. Shock compression along the c-axis is associated with the largest Hugoniot elastic limit (HEL) for this material. Microscopic observation of recovered c-cut samples demonstrated intense twinning with a greater density of twins near the impact surface. The low-energy basal slip was activated by shock loading along the inclined direction and has the smallest HEL. In all cases, we observe the decay of the elastic precursor wave and growth of the HEL with increasing temperature. For the inclined shock compression after the HEL, two plastic waves were found where the stress level of the first plastic wave depends on the peak shock stress. Finally, the largest spall strength was along the transversal direction and the smallest in the off-axis direction. The fracture surface of the sample of transversal orientation contains numerous groves oriented along the base planes of the crystals.
Dynamics of semiflexible scale-free polymer networks
Authors: Galiceanu Mircea , Reis Adriane S. , Dolgushev Maxim
Published: October 2014

Scale-free networks are structures, whose nodes have degree distributions that follow a power law. Here we focus on the dynamics of semiflexible scale-free polymer networks. The semiflexibility is modeled in the framework of [M. Dolgushev and A. Blumen, J. Chem. Phys. 131, 044905 (2009)], which allows for tree-like networks with arbitrary architectures to include local constrains on bond orientations. From the wealth of dynamical quantities we choose the mechanical relaxation moduli (the loss modulus) and the static behavior is studied by looking at the radius of gyration. First we study the influence of the network size and of the stiffness parameter on the dynamical quantities, keeping constant γ, a parameter that measures the connectivity of the scale-free network. Then we vary the parameter γ and we keep constant the size of the structures. This fact allows us to study in detail the crossover behavior from a simple linear semiflexible chain to a star-like structure. We show that the semiflexibility of the scale-free networks clearly manifests itself by displaying macroscopically distinguishable behaviors.
Tuning of multiferroic orders correlated to oxygen stoichiometry in magnetite films
Authors: Dey K. , Ghosh A. , Modak P. , Indra A. , Majumdar S. , Giri S.
Published: October 2014

Magnetite films are grown on Si(100) substrate using pulsed laser deposition technique. The deposition is performed at three fixed oxygen pressures of 0.4 × 10−6, 4.0 × 10−6, and 10 × 10−6  Torr keeping other conditions fixed. Raman and x-ray photoemission spectroscopies confirm formation of single magnetite phase for the first two pressures and a mixed phase composed of magnetite and hematite for the highest pressure. A trivial change in oxygen stoichiometry of magnetite is found crucial for the multiferroic orders at room temperature and below the charge ordering temperature. Possible mechanisms of multiferroic orders driven by change in oxygen stoichiometry are discussed.
Terahertz source at 9.4 THz based on a dual-wavelength infrared laser and quasi-phase matching in organic crystals OH1
Authors: Majkić A. , Zgonik M. , Petelin A. , Jazbinšek M. , Ruiz B. , Medrano C. , Günter P.
Published: October 2014

We present a compact, room temperature, and narrowband terahertz source, based on difference-frequency generation in the organic nonlinear optical crystals OH1 (2-[3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene]malononitrile). The system employs a specific dual-wavelength infrared laser that emits coaxial, synchronous 10-ns pulses of similar energy and duration at wavelengths of 1064 nm and 1030 nm by using Nd:YAG and Yb:YAG crystals within the split laser cavity. The common part of the laser cavity comprises an acousto-optic Q-switch and an output coupler. The output is frequency-mixed in a stack of several OH1 crystals in a quasi-phase-matching configuration, which is determined on the basis of refractive index and absorption measurements in the 1–11 THz range. The system generates terahertz radiation in pulse trains with 1.0 μW average power and a near-Gaussian intensity profile.
Communication: Non-additivity of van der Waals interactions between nanostructures
Authors: Tao Jianmin , Perdew John P.
Published: October 2014

Due to size-dependent non-additivity, the van der Waals interaction (vdW) between nanostructures remains elusive. Here we first develop a model dynamic multipole polarizability for an inhomogeneous system that allows for a cavity. The model recovers the exact zero- and high-frequency limits and respects the paradigms of condensed matter physics (slowly varying density) and quantum chemistry (one- and two-electron densities). We find that the model can generate accurate vdW coefficients for both spherical and non-spherical clusters, with an overall mean absolute relative error of 4%, without any fitting. Based on this model, we study the non-additivity of vdW interactions. We find that there is strong non-additivity of vdW interactions between nanostructures, arising from electron delocalization, inequivalent contributions of atoms, and non-additive many-body interactions. Furthermore, we find that the non-additivity can have increasing size dependence as well as decreasing size dependence with cluster size.
Intermodulation electrostatic force microscopy for imaging surface photo-voltage
Authors: Borgani Riccardo , Forchheimer Daniel , Bergqvist Jonas , Thorén Per-Anders , Inganäs Olle , Haviland David B.
Published: October 2014

We demonstrate an alternative to Kelvin Probe Force Microscopy for imaging surface potential. The open-loop, single-pass technique applies a low-frequency AC voltage to the atomic force microscopy tip while driving the cantilever near its resonance frequency. Frequency mixing due to the nonlinear capacitance gives intermodulation products of the two drive frequencies near the cantilever resonance, where they are measured with high signal to noise ratio. Analysis of this intermodulation response allows for quantitative reconstruction of the contact potential difference. We derive the theory of the method, validate it with numerical simulation and a control experiment, and we demonstrate its utility for fast imaging of the surface photo-voltage on an organic photo-voltaic material.
Highly polarized light emission by isotropic quantum dots integrated with magnetically aligned segmented nanowires
Authors: Uran Can , Erdem Talha , Guzelturk Burak , Perkgöz Nihan Kosku , Jun Shinae , Jang Eunjoo , Demir Hilmi Volkan
Published: October 2014

In this work, we demonstrate a proof-of-concept system for generating highly polarized light from colloidal quantum dots (QDs) coupled with magnetically aligned segmented Au/Ni/Au nanowires (NWs). Optical characterizations reveal that the optimized QD-NW coupled structures emit highly polarized light with an s-to p-polarization (s/p) contrast as high as 15:1 corresponding to a degree of polarization of 0.88. These experimental results are supported by the finite-difference time-domain simulations, which demonstrate the interplay between the inter-NW distance and the degree of polarization.