bluuebunny/crossref_metadata_2025 huggingface dataset:
Micro Imagination: Imagination with an Alternative Framework in a Chemistry Class
Authors: Abdullah Nurdiana , Wahab Nur Bahiyah Abdul , Wai Taufik Lock Kim , Surif Johari
Published: October 2018

The curriculum for the 21st century must be futuristic, flexible and dynamic in order to produce learners with creative and critical thinking. One of the strategies to inculcate creative and critical thinking among students is to train and familiarize learners with the process of generating imagination in teaching and learning. The process of generating imagination corresponds to the characteristics of the subject itself which consists of abstract concepts and complexities. These concepts require students to use their imagination to illustrate concepts, where learners are usually difficult to achieve. Therefore, this study was carried out to identify alternative frameworks in the students’ imaginations of the concept of matter at submicroscopic level. A qualitative study with a descriptive study design is implemented to five secondary school students and ten students of institute of teacher education, aged from 18 to 25 years old. Guided imagery interviews and document analysis are used to collect data from selected students by purposive sampling. The data was analyzed using the grounded theory analysis strategy. The findings show that one of the alternative framework categories found in students’ imagination is micro imagination. The image of hydrogen gas is the ultimate framework of the micro imagination of the most generated structure by the students followed by hydrogen electrons, collision of hydrogen molecules and the formation of water molecules. In this regard, scientific imagination needs to be enhanced by students with emphasis on the concept of science with effective imagination so that students can master chemical concepts at the sub-microscopic level competently. From the conclusion, the implication of the study suggests that teachers should expose to the students the aspects of generative imagination during teaching and learning sessions so that the desired skills can be improved effectively.
Asymptotic expansions and effective boundary conditions: a short review for smooth and nonsmooth geometries with thin layers
Authors: Auvray Alexis , Vial Grégory
Published: October 2018

Problems involving materials with thin layers arise in various application fields. We present here the use of asymptotic expansions for linear elliptic problems to derive and justify so-called ap-proximate or effective boundary conditions. We first recall the known results of the literature, and then discuss the optimality of the error estimates in the smooth case. For non-smooth geometries, the results of [18, 57] are commented and adapted to a model problem, and two improvements of the approximate model are proposed to increase its numerical performance.
Improved sweeping preconditioners for domain decomposition algorithms applied to time-harmonic Helmholtz and Maxwell problems
Authors: Vion Alexandre , Geuzaine Christophe
Published: October 2018

Sweeping-type algorithms have recently gained a lot of interest for the solution of highfrequency time-harmonic wave problems, in particular when used in combination with perfectly matched layers. However, an inherent problem with sweeping approaches is the sequential nature of the process, which makes them inadequate for efficient implementation on parallel computers. We propose several improvements to the double-sweep preconditioner originally presented in [18], which uses sweeping as a matrix-free preconditioner for a Schwarz domain decomposition method. Similarly, the improved preconditioners are based on approximations of the inverse of the Schwarz iteration operator: the general methodology is to apply well-known algebraic techniques to the operator seen as a matrix, which in turn is processed to obtain equivalent matrix-free routines that we use as preconditioners. A notable feature of the new variants is the introduction of partial sweeps that can be performed concurrently in order to make a better usage of the resources. As these modifications still leave some unexploited computational power, we also propose to combine them with right-hand side pipelining to further improve parallelism and achieve significant speed-ups. Examples are presented on high-frequency Helmholtz and Maxwell problems, in two and three dimensions, to demonstrate the properties of our improvements on parallel computer architectures.
Complex intertwinings and quantification of discrete free motions
Authors: Miclo Laurent
Published: October 2018

The traditional quantification of free motions on Euclidean spaces into the Laplacian is revisited as a complex intertwining obtained through Doob transforms with respect to complex eigenvectors. This approach can be applied to free motions on finitely generated discrete Abelian groups: ℤm, with m ∈ ℕ, finite tori and their products. It leads to a proposition of Markov quantification. It is a first attempt to give a probability-oriented interpretation of exp(ξL), when L is a (finite) Markov generator and ξ is a complex number of modulus 1.
La discussion à visée philosophique : un dispositif pédagogique au service d’une éducation plurilingue et interculturelle
Authors: Cayet Anne-Sophie
Published: October 2018

L’appréhension de l’altérité linguistique et culturelle par l’institution scolaire tend souvent à renvoyer les individus à de supposées origines et à les y cantonner. La pédagogie interculturelle, bien qu’elle puisse engendrer des effets de reconnaissance non négligeables, se caractérise souvent, dans la pratique, par des démarches comparatistes relativement artificielles. La mise en oeuvre de Discussions à Visée Philosophique (DVP) auprès d’élèves allophones nouvellement arrivés en France cherche à éviter la tendance culturaliste qui fait de la langue-culture une ressource en elle-même. Elle favorise les échanges plurilingues et interculturels mais toujours au travers des subjectivités individuelles. L’organisation interactionnelle et collaborative de la DVP rend les élèves acteurs de leur apprentissage : ils deviennent les premières ressources de la réflexion philosophique. Ils la co-construisent avec l’aide de leurs camarades et de l’enseignant, à travers un discours qu’ils interrogent constamment. Un outil particulier vient également soutenir les échanges : le « dessin réflexif » (Molinié, 2010). Ce dispositif pédagogique pourrait alors participer à la formation d’une « éducation plurilingue et interculturelle », telle qu’elle est promue par le Conseil de l’Europe (Beacco et al., 2010).
Camera fabula. La caméra, outil et objet sémiotique complexe en interaction
Authors: Thiburce Julien
Published: October 2018

L’enquête sur le sens des pratiques et par les pratiques en interaction se déploie aujourd’hui majoritairement par la mobilisation de la caméra. Les enregistrements audio et vidéo d’un événement offrent au chercheur la possibilité d’observer et d’attester de pratiques langagières et culturelles à différents niveaux de granularité (des traits syntaxiques et sémantiques aux aspects gestuels et corporels).

Néanmoins, son utilisation et son usage ne sont pas sans poser question, tant sur le terrain même de l’enquête que lors de sa programmation et de son traitementa posteriori. De la même manière que Umberto Eco (1979) a porté un regard sur le rôle du lecteur dans l’interprétation d’un récit littéraire, notre proposition questionne la place de la caméra dans l’expérience et l’interprétation de la ville en interaction, au cours d’une balade urbaine proposée par les musées Gadagne (Ville de Lyon). À la croisée de l’ethnométhodologie et de la sémiotique, la caméra émerge à l’intersection entre un outil qui permet d’attester d’une interaction et un objet qui participe de son déroulement par une perception instrumentée.
Social media as political hatred mode in Malaysia’s 2018 General Election
Authors: Chinnasamy Sara , Abdul Manaf Norain
Published: October 2018

In the era of technological advancement, with smartphones and digital devices, almost everybody can have access to the Internet. We move at very fast pace along with the information that we carry and every each of it will rapidly processed. Especially on social media platforms, where false news or scandals that revolve around pundits or the higher up often create chaos and triggers public interest. Malaysia had its 14thGeneral Election (GE14) dated 9thMay, 2018. It was believed to be the most nerve-wracking, fiercest general election to ever happen where after 61 years, Barisan Nasional (BN) had to bow down to the voice of Malaysians where social media is part of the factor, utilised ultimately to influence the people and powerful enough to change people’s perception, thus, create political hatred. A textual analysis was conducted on 187 news on six online news stations’ social media platform during the 11 days of campaigning. In-depth interviews were also conducted to discover the political hatred issues on social media. The findings suggested issues like Goods and Service Tax (GST), candidates’ reputations and 1 Malaysia Development Berhad (1MDB) scandal are the main causes of political hatred expressed on social media platforms.
Non-linguistics Problems in Teaching of Indonesian Language
Authors: Effendi Rustam , Mu’in Fatchul
Published: October 2018

There are two kinds of problems in the teaching of a language, namely: linguistic and non-linguistic problems. These two problems must be handled in balance so that the teaching of language can reach the objective optimally. It is a fact that the non-linguistic problem is not yet seen as a problem in the teaching of a language. Every strategy of a language teaching is done entirely in order to handle the linguistic problems. The consequence of strategies which neglect non-linguistic problems is a less satisfactory result of the language teaching. There are some non-linguistic problems in the teaching of Bahasa Indonesia, some of them are elaborated in this paper, namely: (i) the interlanguage contact in Indonesia, (ii) the attitude of Indonesian people to Bahasa Indonesia, (iii) feeling that Bahasa Indonesia has been spoken well, (iv) legal sanction to those who look down upon Bahasa Indonesia is unavailable yet. (v) teaching materials, especially teaching materials of other than Bahasa Indonesia pay less attention to good and right language, and (vi) not many people can be followed as example in speaking Bahasa Indonesia.
Cultural Violence represented in Indonesia and American Literatures
Authors: Mu’in Fatchul , Effendi Rustam
Published: October 2018

This article is aimed at describing the lives of dominated people of both Indonesia and America. Among the dominated people in Indonesian community are Indonesian Chinese people, and those in American community are African American people. The discussion on some Indonesia novels of post tragedy of 1998 shows that personally Chinese faced a hard life; and socially they were dominated. Therefore, it can be concluded that: (1) the personal behaviour of Indonesian Chinese is represented through the hard life, (2) social behaviour of Indonesian Chinese is represented through the dominated social life, and (3) cultural behavior is represented through the religious life with many problems.This is say that the cultural behaviour of Indonesian Chinese in Indonesia novels is represented through cultural violence. The similar result of discussion on some American novels of post slavery shows that (1) the black man as the representation of Black people (African-Americans) was always in a dilemmatic condition leaving him without any options. Whatever he chose, will have negative consequences, (2) the struggle for ‘equality’ through ‘violence’ will result in a ‘tragic fate’, and (3) the novel reflected the black people who yearned for freedom from white domination and expected to have good education, good employment, and equality in political opportunity, law enforcement/law protection, and in other sociocultural life.
Investigation the effects of comparison between bilingual instruction and the use of L2
Authors: Mirzaei Fatemeh , Tony Lim Bin Abdullah Muhammad Ridhuan , B Abu Bakar Zulqarnain , Sattar Waseem
Published: October 2018

This paper is a comparison of the impact of using bilingual instruction and the use of L2 on learners’ learning improvement. The mixed mode is used to determine the use of mother language (L1) as a resource helped the students in learning. The respondents were selected from faculty of Management in UTM, Malaysia. They used rarely English language outside of the school and had average level of English language proficiency. In this paper, it also distinguished resource, difficulties and challenges which the students faced in using bilingual instruction. The questionnaire was used to determine students’ perceptions and data was analyzed by SPSS. In addition, the data was collected from interview which is transcribed and described. The results indicated that L1 in UTM can be used as a resource to teach specific subjects to students. According to the results, respondents had positive attitudes about using bilingual instruction in the class and it was effective on students’ leaning improvement. Based on findings, it is hoped that positive feedback in this research provide a reason why L1 should be used in teaching and look it as a resource for language learning in the future.
The Mediating Effects of Quality Learning on the Overall Learning Experience and Learning Outcomes of STEM Malaysian Students
Authors: Choy S. Chee , Yim Joanne Sau Ching , Tan Poh Leong
Published: October 2018

This study examines the mediating effects of quality learning on the overall learning experience, and learning outcomes for a sample of 1180 Malaysian STEM students. Data were collected using the Quality Assurance Perception Questionnaire for Students (QAPQ-S), a self-reported questionnaire designed to measure students’ perceptions of learning quality in higher education. The contribution of this study is the empirical examination of the main exogenous variables in greater depth using SEM-PLS. The research fills a gap in the literature through its analysis of the mediating role of quality learning. The results show that quality learning is a significant mediator of learning skills, teacher support and curriculum in the achievement of learning outcomes. Quality learning fully mediates learning skills and learning outcomes while partially mediating the other relationships. Limitation and implications for practice are also discussed.
Hygienemaßnahmen bei MRSA in (Reha-)Kliniken, Pflegeheimen und häuslicher Krankenpflege
Authors: Jatzwauk Lutz
Published: October 2018

Herausforderung Auch mit MRSA besiedelte oder infizierte Patienten haben Anspruch auf rehabilitative Leistungen und ausreichende pflegerische und
medizinische Betreuung. Gleichzeitig erwarten berechtigterweise von MRSA nicht betroffene Patienten, durch geeignete Maßnahmen vor einer Besiedlung mit dem Keim
geschützt zu werden. Wie kann das gelingen?
„Patientenkarriere“ von der Akutversorgung bis zur Nachsorge – wo knirscht es?
Authors: Agor Karin
Published: October 2018

Problempotenzial Eine Akutversorgung im Krankenhaus kann für ältere Menschen an sich schon eine Situation sein, die sie an die Grenzen ihrer Ressourcen
bringt. Ein großes Potenzial an Problemen ergibt sich jedoch auch auf dem weiteren Versorgungsweg.
Prävention für multimorbide ältere Menschen im ambulanten Bereich
Authors: Kasprick Lysann , Wilke Cornelia , Zimmer Katrin , Winkelmann Claudia
Published: October 2018

Konzept Was verstehen wir unter ambulanter Prävention für multimorbide ältere Menschen bis hin zum geriatrischen Patienten? Wie werden die präventiven
Patienten herausgefunden oder betrachten wir alle Patienten in der haus- und fachärztlichen Praxis präventiv? Wie gestaltet sich der Wechsel zwischen den
Sektoren ambulant und stationär? Wird der Wandel der Digitalisierung oder Medizin 4.0 auch für diesen Bereich zutreffend sein? Wie reagieren die Patienten und
ihre Angehörigen auf diese ergänzende Rehabilitationsform?
Transition-Metal-Catalyzed Cross-Coupling with Non-Diazo Carbene Precursors
Authors: Wang Jianbo , Wang Kang
Published: October 2018

Transition-metal-catalyzed cross-coupling reactions through metal carbene migratory insertion have emerged as powerful methodology for carbon–carbon bond constructions. Typically, diazo compounds (or in situ generated diazo compounds from N-tosylhydrazones) have been employed as the metal carbene precursors for this type of cross-coupling reactions. Recently, cross-coupling reactions employing non-diazo carbene precursors, such as conjugated ene-yne-ketones, allenyl ketones, alkynes, cyclopropenes, and Cr(0) Fischer carbenes, have been developed. This account will summarize our efforts in the development of transition-metal-catalyzed cross-coupling reactions with these non-diazo carbene precursors.

1 Introduction

2 Cross-Coupling with Ene-yne-ketones, Allenyl Ketones, and Alkynes

3 Cross-Coupling Involving Ring-Opening of Cyclopropenes

4 Palladium-Catalyzed Cross-Coupling with Chromium(0) Fischer Carbenes

5 Conclusion
Endoscope-Assisted Retrosigmoid Approach for Cerebellopontine Angle Epidermoid Tumor
Authors: Vaz-Guimaraes Francisco , Gardner Paul , Fernandez-Miranda Juan
Published: October 2018

Objectives Surgical resection is the only effective treatment modality for epidermoid tumors. Complete resection with preservation of neurological function must be pursued whenever possible, because it offers a cure for patients. However, the inability to identify hidden remnants, interdigitating around cranial nerves, especially in larger tumors, may be a contributing factor for incomplete resection. This operative video demonstrates the technical nuances in achieving complete resection of a cerebellopontine angle epidermoid tumor via an endoscope-assisted retrosigmoid approach.

Design and Setting Operative video of an endoscope-assisted retrosigmoid, approach for complete resection of a cerebellopontine angle epidermoid tumor. The patient was a 16-year-old female, who presented with 1-year history of worsening headaches and imbalance. Her neurological exam was normal, including normal cranial nerve function, and hearing. Radiological evaluation revealed an epidermoid tumor in the right cerebellopontine angle, extending to the interpeduncular cistern. Surgical resection was recommended. Given extension of the tumor across the midline, an endoscope-assisted procedure was planned to increase the odds of complete resection.

Results The video demonstrates the surgical technique applied for tumor resection. The patient's clinical symptoms resolved completely after surgery and she remained neurologically intact. Postoperative magnetic resonance imaging (MRI) confirmed complete tumor resection. There were no postoperative complications.

Conclusions The use of endoscopic techniques for resection of cerebellopontine angle epidermoid tumor is safe and effective and may increase the odds of complete resection, especially in larger tumors spreading across the midline, by enabling the surgeon clear visualization of deep-seated and contralateral relevant neurovascular structures, not readily accessible by the surgical microscope.

The link to the video can be found at: https://youtu.be/X6YP_7OeQQE.
Two Decades of Contemporary Surgery of Primary Cardiac Tumors
Authors: Jawad Khalil , Owais Tamer , Feder Stefan , Lehmann Sven , Misfeld Martin , Garbade Jens , Borger Michael
Published: October 2018

Objective The decision to operate cardiac tumors is an issue of balancing surgical outcome and survival with quality of life (QOL). We report our single-center experience in managing primary cardiac tumors between 1994 and 2014.

Methods and Results In this study, 269 patients were subjected to our standardized operative protocols, preoperative preparations, postoperative follow-up, and consents of participation. Demographic and preoperative/intraoperative/postoperative variables were collected with focus on long-term follow-up and survival. A total of 72,000 cardiac procedures were performed within 20 years at our institution. Two hundred sixty-nine patients were diagnosed with primary cardiac tumors (0.37%), with a male:female ratio of 1:1.68, mean age of 57.4 ± 19.5 years, and body mass index of 25.49 ± 6.5. The most presenting symptoms were dyspnea (n = 94), arrhythmias (n = 53), embolic event (n = 36), and chest pain (n = 29), and 33 patients were accidentally discovered. Isolated tumor excision and concomitant ablation were performed on 181 patients, while the rest needed additional procedures such as coronary artery bypass grafting (n = 27) or valve surgery (n = 61). Focus on pathology, tumor location was done reporting the commonest pathology such as myxoma (n = 177) and fibroelastoma (n = 56). The frequent site was the left atrium (n = 162). Our primary results showed incidence of bleeding in 9 patients (3.3%), arrhythmias in 76 patients (28.25%), and mortality in 49 patients (18.2%). Five patients (1.8%) showed recurrence and 220 patients (81.8%) showed complaint-free survival.

Conclusion Complete excision of primary cardiac tumors is the golden rule in management as it improves survival and decreases morbidity expected from the progressing tumors process. The progression of minimally invasive techniques improves QOL and should be performed whenever possible.
Evaluation of the Extent of Vessel Avulsion Injury: An Experimental Study Using a Rabbit Model
Authors: Uraloğlu Muhammet , Ural Alper , Saygın İsmail , Livaoğlu Murat , Karaçal Naci
Published: October 2018

Background Determining the extent of damage in vascular avulsion type injuries still represents a challenge for the microsurgeon. Excision of the damaged section is critical for the success of anastomosis. The purpose of this study was to determine which among vascular endothelial and adventitia damage findings is most effective in determining the extent of avulsion injury.

Methods Varying degrees of avulsion were applied to the aorta of 12 (n = 12) adult female New Zealand rabbits. Avulsion was first determined using adventitial findings and then with endothelial findings. The definitive extent of damage was determined histopathologically.

Results The mean area of the histopathological sections was 16.7 ± 6.9 mm. The extent of damage measured from the adventitia was 15.8 ± 7.9 mm (the difference in histopathological examinations was not significant, p = 0.590, paired t-test), while the extent of damage from the lumen was 13.3 ± 8.2 mm (the difference in histopathological examinations was significant p = 0.004, paired t-test).

Conclusion Excision based on adventitia findings is more effective in case of avulsion injury.
Diagnostik und Therapie der Internetabhängigkeit
Authors: te Wildt Bert
Published: October 2018

Mindestens 1% der Jugendlichen oder Erwachsenen erfüllt die Suchtkriterien der Internetabhängigkeit – mit steigender Tendenz. Risiken dafür haben Personen mit geringer Offline-Selbstwirksamkeit. Diesen kann mit kognitiv-behavioraler Therapie geholfen werden.
Quantitative monitoring of the internal field in the depletion layer of a GaAs-based solar cell with terahertz radiation
Authors: Miyagawa Keita , Nagai Masaya , Yamashita Genki , Ashida Masaaki , Kim Changsu , Akiyama Hidefumi , Kanemitsu Yoshihiko
Published: October 2018

We measured the time profiles of terahertz (THz) radiation emitted from a GaAs-based solar cell under weak excitation with ultrashort optical pulses. The time-domain THz waveform directly reflects the characteristic saturation and overshooting of the drift current under high fields in the thin depletion layer of the solar cell, from which we can evaluate the internal electric field quantitatively. We also measured the time profiles of THz radiation for simultaneous excitation with ultrashort pulses and continuous light and observed the reduction of the internal field in the depletion layer of the solar cell during operation. Since nonlinear responses of the drift current in the depletion layer can be observed, we conclude that THz measurements provide a key technology for characterizing the solar cell performance that can be expected under practical operating conditions.
Experimental comparison of spherically bent HAPG and Ge crystals
Authors: Hell N. , Lockard T. , Beiersdorfer P. , Magee E. W. , Brown G. V. , Shepherd R. , Arthanayaka T.
Published: October 2018

The Orion high-resolution X-ray (OHREX) imaging spherically bent crystal spectrometer, operated with both image plates and CCD cameras, provides time-averaged plasma diagnostics through high-resolution spectroscopy with good signal-to-noise at the Orion laser facility. In order to provide time-resolved spectra, the OHREX will be outfitted with a streak camera, and in this case, even higher signal to noise will be desired. Using the OHREX’s sister instrument, the EBIT High-resolution X-ray (EBHiX) spectrometer, at the LLNL electron beam ion trap EBIT-I, we therefore compare the efficiency of a high-quality Ge (111) crystal (2d = 6.532 Å) with that of a higher integrated reflectivity, but lower-resolution highly annealed pyrolytic graphite (HAPG) crystal (2d = 6.708 Å) in the energy range 2408–2452 eV. We find that the HAPG provides overall more signal across the entire image; however, because of the much better focusing properties of the Ge crystal, the latter provides more signal within the central 100 μm of the spatial profile in the cross-dispersion direction and is thus more suitable for the narrow entrance window of the Livermore-built streak camera.
Contributed Review: Instruments for measuring Seebeck coefficient of thin film thermoelectric materials: A mini-review
Authors: Wang Chen , Chen Fenggui , Sun Kuan , Chen Rui , Li Meng , Zhou Xiaoyuan , Sun Yuyang , Chen Dongyang , Wang Guoyu
Published: October 2018

Thin film thermoelectric materials (TF TEMs) based on organic semiconductors or organic/inorganic composites exhibit unique properties such as low-temperature processability, mechanical flexibility, great freedom of material design, etc. Thus they have attracted a growing research interest. Similar to inorganic bulk thermoelectric materials (IB TEMs), the Seebeck coefficient combined with electrical conductivity and thermal conductivity is a fundamental property to influence the performance of TF TEMs. However, due to the differences in material and sample geometries, the well-established characterization devices for IB TEMs are no longer applicable to TF TEMs. And until now, a universal standard of measuring the Seebeck coefficient of TF TEMs is still lacking. This mini-review presents the development of instruments designed for measuring the Seebeck coefficient of TF TEMs in the last decade. Primary measurement methods and typical apparatus designs will be reviewed, followed by an error analysis induced by instrumentation. Hopefully this mini-review will facilitate better designs for a more accurate characterization of the Seebeck coefficient of thin film thermoelectric materials.
Infrared imaging systems for wall protection in the W7-X stellarator (invited)
Authors: Jakubowski Marcin , Drewelow Peter , Fellinger Joris , Puig Sitjes Aleix , Wurden Glen , Ali Adnan , Biedermann Christoph , Cannas Barbara , Chauvin Didier , Gamradt Marc , Greve Henry , Gao Yu , Hathiramani Dag , König Ralf , Lorenz Axel , Moncada Victor , Niemann Holger , Ngo Tran Thanh , Pisano Fabio , Sunn Pedersen Thomas ,   W7-XTeam
Published: October 2018

Wendelstein 7-X aims at quasi-steady state operation with up to 10 MW of heating power for 30 min. Power exhaust will be handled predominantly via 10 actively water cooled CFC (carbon-fiber-reinforced carbon) based divertor units designed to withstand power loads of 10 MW/m2 locally in steady state. If local loads exceed this value, a risk of local delamination of the CFC and failure of entire divertor modules arises. Infrared endoscopes to monitor all main plasma facing components are being prepared, and near real time software tools are under development to identify areas of excessive temperature rise, to distinguish them from non-critical events, and to trigger alarms. Tests with different cameras were made in the recent campaign. Long pulse operation enforces additional diagnostic design constraints: for example, the optics need to be thermally decoupled from the endoscope housing. In the upcoming experimental campaign, a graphite scraper element, in front of the island divertor throat, will be tested as a possible means to protect the divertor pumping gap edges during the transient discharge evolution.
Soft X-ray backlighter source driven by a short-pulse laser for pump-probe characterization of warm dense matter
Authors: McGuffey C. , Dozières M. , Kim J. , Savin A. , Park J. , Emig J. , Brabetz C. , Carlson L. , Heeter R. F. , McLean H. S. , Moody J. , Schneider M. B. , Wei M. S. , Beg F. N.
Published: October 2018

Here we propose a pump-probe X-ray absorption spectroscopy temperature measurement technique appropriate for matter having temperature in the range of 10 to a few 100 eV and density up to solid density. Atomic modeling simulations indicate that for various low- to mid-Z materials in this range the energy and optical depth of bound-bound and bound-free absorption features are sensitive to temperature. We discuss sample thickness and tamp layer considerations. A series of experimental investigations was carried out using a range of laser parameters with pulse duration ≤5 ps and various pure and alloyed materials to identify backlighter sources suitable for the technique.
Multiple solutions, oscillons, and strange attractors in thermoviscoelastic Marangoni convection
Authors: Lappa Marcello , Ferialdi Hermes
Published: October 2018

Through numerical solution of the governing time-dependent and non-linear Navier-Stokes equations cast in the framework of the Oldroyd-B model, the supercritical states of thermal Marangoni-Bénard convection in a viscoelastic fluid are investigated for increasing values of the relaxation time while keeping fixed other parameters (the total viscosity of the fluid, the Prandtl number, and the intensity of the driving force, Ma = 300). A kaleidoscope of patterns is obtained revealing the coexistence of different branches of steady and oscillatory states in the space of parameters in the form of multiple solutions. In particular, two main families of well-defined attractors are identified, i.e., multicellular steady states and oscillatory solutions. While the former are similar for appearance and dynamics to those typically produced by thermogravitational hydrodynamic disturbances in layers of liquid metals, the latter display waveforms ranging from pervasive standing waves to different types of spatially localised oscillatory structures (oscillons). On the one hand, these localised phenomena contribute to increase the multiplicity of solutions and, on the other hand, they give rise to interesting events, including transition to chaos and phenomena of intermittency. In some intervals of the elasticity number, the interference among states corresponding to different branches produces strange attractors for which we estimate the correlation dimension by means of the algorithm originally proposed by Grassberger and Procaccia.
Sensitivity of modeled microscale gas breakdown voltage due to parametric variation
Authors: Dynako Samuel D. , Loveless Amanda M. , Garner Allen L.
Published: October 2018

Device miniaturization increases the importance of understanding and predicting gas breakdown and electrical discharge thresholds. At gap sizes on the order of ten microns at atmospheric pressure, field emission drives breakdown rather than Townsend avalanche. While numerical and analytical models can demonstrate this transition, a quantitative understanding of the relative importance of each parameter remains unclear. Starting from a universal model for gas breakdown across the field emission and Townsend avalanche regimes [A. M. Loveless and A. L. Garner, Phys. Plasmas 24, 113522 (2017)], this paper applies the concept of error propagation from ionizing radiation measurements to determine the relative impact of each factor on the predicted breakdown voltage. For limits of both large and small products of the dimensionless ionization coefficient, α¯, and gap distance, d¯, the electrode work function has the largest relative effect on the predicted breakdown voltages with a deviation of 50% in the work function resulting in an uncertainty in the calculated breakdown voltage of ∼84% for both α¯d¯≫1 and α¯d¯≪1. This quantifies the significance of nonuniformities in material surfaces and changes in the surface structure during multiple electric field applications and help predict the breakdown voltage for small gaps, motivating better electrode characterization both initially and during repeated operation.
Magnetic properties of mixed sodium-lithium iron fluorophosphate NaLiFePO4F cathode material
Authors: Seo Jae Yeon , Choi Hyunkyung , Kim Chul Sung
Published: October 2018

Mixed sodium-lithium iron fluorophosphates NaLiFePO4F was synthesized by solid-state route. The crystal and magnetic properties were investigated by X-ray diffraction (XRD) measurement, vibrating sample magnetometer (VSM), and Mössbauer spectroscopy. The crystal structure of NaLiFePO4F was determined to be orthorhombic with space group of Pnma. The cell parameters of NaLiFePO4F are as follows: a0 = 10.9661 Å, b0 = 6.3693 Å, c0 = 11.4342 Å, and V = 798.6377 Å3. The temperature-dependence of the zero-field-cooled (ZFC) and field-cooled (FC) curves was examined by VSM at 100 Oe from 4.2 to 295 K. We determined the Néel temperature (TN = 22 K) and spin reorientation temperature (TS = 13 K). The Mössbauer spectra of NaLiFePO4F were taken at various temperatures ranging from 4.2 to 295 K. At below TS, the electric quadrupole splitting (ΔEQ) decreased and magnetic hyperfine field (Hhf) increased with decrease temperature due to spin-orbit coupling.
Continuous repetition rate tuning from 960 MHz to 1.72 GHz of a sub-300 femtosecond mode-locked semiconductor disk laser
Authors: Chen Sverre T. , Woods J. R. C. , Polanik M. , Unger P. , Tropper A. C. , Apostolopoulos V.
Published: October 2018

Vertical External Cavity Surface Emitting semiconductor Lasers rely on Semiconductor Saturable Absorbing Mirrors for mode-locking, allowing laser cavities to be designed far from stability limits. We have harnessed this feature to study repetition rate tunability. The cavity element separations were determined by a coded cavity design protocol based on cavity round trip matrix calculations. We produced a sub-300-fs near transform-limited pulse train with a repetition rate of 0.96 MHz–1.72 GHz, at 1035 nm and an average power of 50 mW.
Design, development, and testing of an environmental P-T cell for infrared spectroscopy measurements
Authors: De Angelis S. , Ferrari M. , De Sanctis M. C. , Biondi D. , Boccaccini A. , Morbidini A. , Formisano M. , Ammannito E. , Di Iorio T.
Published: October 2018

Water absorption bands due to superficially adsorbed molecules often dominate the near-infrared spectra of particulate minerals and rocks, when measured in the laboratory in the reflectance mode. In order to remove this, the spectral effect is thus necessary to acquire spectra of samples in vacuum and at higher temperatures. With the aim to accomplish this task, we developed an environmental cell to perform infrared spectroscopic measurements at controlled pressure-temperature conditions. Currently the cell allows one to measure reflectance spectra in the temperature range from room values up to 300 °C (573 K), in the pressure range of 103–10−6 mbar. The acquisition of spectra continuously in two distinct phases, namely, during a preliminary pumping stage (at room T) and subsequently during a heating stage (in vacuum), permits to highlight and characterize separately the effect of pressure and temperature on infrared spectra.
Nano-composites for enhanced catastrophic failure temperature of organic light-emitting diodes
Authors: Yang Han-Nan , He Shou-Jie , Zhang Tao , Man Jia-Xiu , Jiang Nan , Wang Deng-Ke , Lu Zheng-Hong
Published: October 2018

Thermal stability is one of the key technical challenges in developing high brightness organic light-emitting diodes (OLEDs). In this study, thermal catastrophic failure, a process involving temperature-induced abrupt device breakdown, is found to have a high degree of correlation to the glass transition process of the organic molecules. It is also found that C60-organic nano-composites can be used effectively to increase the glass transition temperature of the organic small molecular thin-films leading to the improvement of the thermal stability of OLEDs. In addition, a universal mathematical formula with only one variable, concentration, is discovered to quantify well the glass transition temperatures of all C60 nano-composites. The thermal catastrophic failure temperature of OLEDs with C60 nano-composites as a hole transport layer is found to be proportional to the glass transition temperature of C60 nano-composites.
Narrowband thermal emission from Tamm plasmons of a modified distributed Bragg reflector
Authors: Wang Zhiyu , Clark J. Kenji , Ho Ya-Lun , Vilquin Bertrand , Daiguji Hirofumi , Delaunay Jean-Jacques
Published: October 2018

Tamm plasmons (TPs), which exist at the interface between a metallic film and a distributed Bragg reflector (DBR), can be thermally excited and then out-coupled as thermal radiation, providing a means to realize easy-to-fabricate and wavelength-selective infrared emitters. A modified TP structure consisting of a DBR having a thick layer adjacent to the metallic film is proposed and high-intensity and narrowband thermal emission of the structure is demonstrated. The modified TP structure sustains a higher order TP mode with a higher quality factor (Q-factor) emittance peak than a standard TP structure. The measurement of the emission at 150 °C of the proposed TP structure reveals an emittance peak with a maximum value of 0.94, a background of 0.01, and a Q-factor of 48 at a wavelength around 5 μm. Moreover, a wide range of emission wavelengths (from 4.4 μm to 5.7 μm) is experimentally realized by adjusting the last DBR-layer thickness, thus demonstrating a fine selection of the emission peak wavelength.
Controlling nanoscale air-gaps for critically coupled surface polaritons by means of non-invasive white-light interferometry
Authors: Pufahl Karsten , Passler Nikolai Christian , Grosse Nicolai B. , Wolf Martin , Woggon Ulrike , Paarmann Alexander
Published: October 2018

We report an experimental method to control large-area air-gaps in the nanometer range for evanescent coupling of light to surface waves such as surface plasmon polaritons or surface phonon polaritons. With the help of spectrally resolved white-light interferometry, we are able to stabilize and tune the gap with nanometer precision and high parallelism. Our technique is non-invasive and leaves the coupling area unobstructed, and the setup delivers reference-free real-time readout up to a distance of 150 μm between the coupling prism and the sample. Furthermore, we demonstrate the application to prism coupled surface polariton excitation. The active gap control is used to determine the dispersion of a critically coupled surface phonon polariton over a wide spectral range in the mid infrared region.
Manipulation of fast and slow light propagation by photonic-molecule optomechanics
Authors: Chen Hua-Jun
Published: October 2018

We demonstrate theoretically coherent optical propagation in a composite photonic-molecule-cavity optomechanical system consisting of two whispering-gallery microcavities in which one of the optical cavities is optomechanical with high cavity dissipation and the other is an auxiliary with a high quality factor. Optomechanically induced transparency and its related propagation properties such as fast and slow light effects are investigated based on the hybrid system for suitable parametric regimes. By controlling the coupling strength J between the two cavities, which is determined by their distance and the decay rate ratio δ of the two cavities, tunable and controllable fast-to-slow light propagation (or vice versa) can be achieved. Our study may provide a further insight of the composite photonic-molecule optomechanical systems and may open up promising on-chip applications in quantum information processing.
Improving maximum count rate of superconducting nanowire single-photon detector with small active area using series attenuator
Authors: Lv Chaolin , Zhang Weijun , You Lixing , Hu Peng , Wang Heqing , Li Hao , Zhang Chengjun , Huang Jia , Wang Yong , Yang Xiaoyan , Wang Zhen , Xie Xiaoming
Published: October 2018

Maximum count rate is a crucial parameter of superconducting nanowire single-photon detector (SNSPD) for quantum communication and laser communication. However, when increasing the incident photon flux, the SNSPD device with small active area is apt to latch due to the AC coupling of room temperature amplifier in the readout circuit, which limits SNSPD to reach a high count rate. We proposed a simple way by inserting an electrical attenuator in series with small-active area SNSPD to avoid the latching effect, thus improving maximum count rate effectively. The count rate with the system detection efficiency reduced by half increased by 6 times for SNSPD with an active area of Φ15 μm.
Enhanced magnon spin transport in NiFe2O4 thin films on a lattice-matched substrate
Authors: Shan J. , Singh A. V. , Liang L. , Cornelissen L. J. , Galazka Z. , Gupta A. , van Wees B. J. , Kuschel T.
Published: October 2018

We investigate magnon spin transport in epitaxial nickel ferrite (NiFe2O4, NFO) films grown on magnesium gallate spinel (MgGa2O4, MGO) substrates, which have a lattice mismatch with NFO as small as 0.78%, resulting in the reduction of antiphase boundary defects and thus in improved magnetic properties in the NFO films. In nonlocal transport experiments where platinum (Pt) strips function as magnon spin injectors and detectors, enhanced signals are observed for both electrically and thermally excited magnons, and the magnon relaxation length (λm) of NFO is found to be around 2.5 μm at room temperature. Moreover, at both room and low temperatures, we present distinct features from the nonlocal spin Seebeck signals which arise from magnon-polaron formation. Our results demonstrate excellent magnon transport properties (magnon spin conductivity, λm, and spin mixing conductance at the Pt/NFO interface) of NFO films grown on a lattice-matched substrate which are comparable with those of yttrium iron garnet.
Noise characterization of patch antenna THz photodetectors
Authors: Palaferri D. , Todorov Y. , Gacemi D. , Barbieri S. , Li L. H. , Davies A. G. , Linfield E. H. , Sirtori C.
Published: October 2018

Current noise fluctuations have been investigated in terahertz (THz) quantum well photodetectors embedded in antenna-coupled photonic architectures and compared with standard substrate-coupled mesa detectors. The noise measurements give a value of the photoconductive gain that is in excellent agreement with that extracted from previous responsivity calibrations. Moreover, our results confirm that the noise equivalent power (NEP) of the antenna-coupled devices is of the order of 0.2 pW/Hz0.5. This low NEP value and the wide band frequency response (∼GHz) of the detectors are ideal figures for the development of heterodyne receivers that are, at present, a valuable technological solution to overcome the current limitation of THz sensors.
The role of adsorbed water on TiO2 particles in the electrorheological effect
Authors: Qiu Zhaohui , Huang Jing , Shen Rong , Wang Ying , Wu Xiaoyi , Lu Kunquan , Xiong Xiaomin
Published: October 2018

TiO2 particles prepared by the hydrolysis of titanium butoxide adsorb water molecules with different adsorption energies. The electrorheological (ER) fluid composed of TiO2 particles behaves as the polar-molecule giant electrorheological (GER) fluid at 25°C even after thermal treatment at 75°C. After thermal treatment at 125°C and 175°C, the water molecules with low adsorption energy are removed and the ER fluid behaves as traditional ER fluid at 25°C. However, at 175°C, the ER fluid treated at 175°C behaves as a polar-molecule GER fluid when the external electric field is larger than 2 kV/mm. These results show that the water molecules with low adsorption energy act as polar molecules responsible for the GER effect and, with the help of thermal energy, water molecules with high adsorption energy can work as those with low adsorption energy, resulting in the GER effect.
Fine tuning the electro-mechanical response of dielectric elastomers
Authors: Zurlo Giuseppe , Destrade Michel , Lu Tongqing
Published: October 2018

We propose a protocol to model accurately the electromechanical behavior of dielectric elastomer membranes using experimental data of stress-stretch and voltage-stretch tests. We show how the relationship between electric displacement and the electric field can be established in a rational manner from these data. Our approach demonstrates that the ideal dielectric model, prescribing linearity in the purely electric constitutive equation, is quite accurate at low-to-moderate values of the electric field and that, in this range, the dielectric permittivity constant of the material can be deduced from stress-stretch and voltage-stretch data. Beyond the linearity range, more refined couplings are required, possibly including a non-additive decomposition of the electro-elastic energy. We also highlight that the presence of vertical asymptotes in voltage-stretch data, often observed in the experiments just prior to failure, should not be associated with strain stiffening effects but instead with the rapid development of electrical breakdown.
Preliminarily optimizing glass-forming compositions in metal-metal type ternary alloy systems with a large-sized solvent element
Authors: Wang S. H. , Li D. F. , Song K. K. , Sun H. G. , Wu S. , Yan D. L. , Xue Q. S. , Zhang Z. Q. , Song B. , Peng C. X. , Li X. L. , Wang L.
Published: October 2018

Glass-forming ability (GFA) is crucial for designing bulk metallic glasses. In this work, it was found that when the content of the solvent element with an atomic radius larger than 1.58 Å in one ternary alloy system is fixed, their entropy of mixing (ΔSmix) vs. the enthalpy of mixing (ΔHmix) curve display a slant arc shape. The compositions locating around the inflection point of each ΔHmix vs. ΔSmix curve usually show an optimal GFA. Its feasibility was verified in Zr-, La-, and Ca-based ternary systems. By considering both calculated inflection points and experimental results, the optimizing glass-forming compositions can be roughly estimated by a proposed formula under limited conditions. Our studies could provide a simple method for preliminarily selecting good glass-formers when the content of the solvent element in one ternary alloy system is fixed.