bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of Dynamic Errors in Laser Optoelectronic Dimension Gauges for Geometric Measurement of Details
Authors: Khasanov Zimfir , Yasoveev Vasikh , Khasanov Oleg , Vishnevskiy Alexandr
Published: February 2018

The article reviews the capabilities and particularities of the approach to the improvement of metrological characteristics of fiber-optic pressure sensors (FOPS) based on estimation estimation of dynamic errors in laser optoelectronic dimension gauges for geometric measurement of details. It is shown that the proposed criteria render new methods for conjugation of optoelectronic converters in the dimension gauge for geometric measurements in order to reduce the speed and volume requirements for the Random Access Memory (RAM) of the video controller which process the signal. It is found that the lower relative error, the higher the interrogetion speed of the CCD array. It is shown that thus, the maximum achievable dynamic accuracy characteristics of the optoelectronic gauge are determined by the following conditions: the parameter stability of the electronic circuits in the CCD array and the microprocessor calculator; linearity of characteristics; error dynamics and noise in all electronic circuits of the CCD array and microprocessor calculator.
Modeling of Acoustic Processes in Solids Based on Particle Interaction
Authors: Kuzovova Angela , Muksunov Timur
Published: February 2018

An algorithm for the numerical propagation of acoustic waves in solids has been developed. The algorithm is based on the particles interaction model of in a tetrahedral crystal lattice. Numerical integration of Newton's equations in the calculation of particle trajectories is applied. The possibility of numerical modeling of wave diffraction processes on heterogeneities is shown. The resonant phenomena are observed in simulation of acoustic oscillations for an ultrasonic waveguide by means of proposed algorithm.
Principles and Mechanisms of Brain Functioning
Authors: Shumilov Vladimir
Published: February 2018

Principles of brain functioning and a mechanism for their realization are formulated in the paper. An absolutely local mechanism provides independent of any external control formation of traces of events in the form of connections between neurons (accumulation of experience), storage of these traces (fading memory), interpretation of traces (response to the impact of the environment in accordance with accumulated experience). Traces of events influence formation of the pathways of signals from the receptors to the effectors and, consequently, the organism’s reaction. Retraining is provided by formation of new and therefore stronger links.
Solar Power Installation for the Territory of Siberia
Authors: Boyakhchyan Arman , Okhorzina Alyona , Kshalova Aygul
Published: February 2018

This article describes combined solar systems with liquid cooling are considered in this article. Solar power systems have long been popular in Europe, but in the Siberian climate these systems were considered to be inappropriate. The paper argues that such installations may be used even in Siberia, and in some regions it will be economically profitable. In this article describe an installation that was assembled to carry out field experiments.
Effet du plasmon de surface localisé sur les propriétés des sources organiques (OLED)
Authors: Khadir Samira , Chakaroun Mahmoud , Boudrioua Azzedine
Published: February 2018

L’utilisation de l’effet plasmonique de nanoparticules métalliques (NP) est l’une des voies les plus prometteuses pour améliorer les performances optiques et électriques des diodes électroluminescentes organiques (OLED). Le choix du métal, la taille et la position des NP sont liés aux propriétés physiques recherchées mais aussi aux approches et aux techniques permettant leur fabrication. Deux approches peuvent être utilisées : random metallic nanoparticules (RMN) et periodic metallic nanoparticules (PMN).
Métamatériaux pour la protection sismique
Authors: Guenneau Sébastien , Enoch Stefan , Colombi Andrea , Roux Philippe , Brule Stéphane
Published: February 2018

Les physiciens des ondes élaborent des modèles théoriques et numériques pour un contrôle accru de la lumière dans des matériaux structurés à l’échelle nanométrique et s’en inspirent pour contrôler les ondes mécaniques de Rayleigh dans des sols structurés à l’échelle métrique, avec des trous dans un sol ou des arbres en surface savamment agencés. Un transfert de paradigme s’opère entre les métamatériaux électromagnétiques pour la photonique et les métamatériaux sismiques pour le génie civil.
Lithium Treatment in Children and Adolescents
Authors: Duffy Anne , Grof Paul
Published: February 2018

Introduction There is a resurgence of interest in lithium treatment of bipolar disorders in part related to its unique anti-suicidal and neuroprotective effects.

Methods This is a narrative review of key studies pertaining to the effectiveness and tolerability of lithium treatment in pediatric populations.

Results Evidence supports that lithium is an effective and generally well-tolerated acute treatment for pediatric mania compared to placebo. Lithium may be less effective than risperidone for treating chronic mixed/manic symptoms in young children but comparable to anticonvulsants. However, in comparison, risperidone was associated with higher weight gain and prolactin levels. There is a lack of evidence inform maintenance treatment in children who benefit from lithium. Other indications that require further study include treatment of refractory or recurrent major depression in children at confirmed familial risk of bipolar disorder, as well as the treatment of acute suicidal ideation/behavior and refractory aggression.

Discussion There is inadequate data about the full variety of benefit and tolerability of lithium treatment in pediatric patients. However, given the potential for protection against suicide and neurotoxic effects of illness, further studies should be a priority.
Potential Therapeutic Benefits of Green and Fermented Rooibos (Aspalathus linearis) in Dermal Wound Healing
Authors: Pringle Nadine , Koekemoer Trevor , Holzer Andrea , Young Carly , Venables Luanne , van de Venter Maryna
Published: February 2018

The process of wound healing constitutes an ordered sequence of events that provides numerous opportunities for therapeutic intervention to improve wound repair. Rooibos, Aspalathus linearis, is a popular ingredient in skin care products, however, little scientific data exists exploring its therapeutic potential. In the present study, we evaluated the effects of fermented and aspalathin-enriched green rooibos in various in vitro models representative of dermal wound healing. Treatment of RAW 264.7 macrophages with fermented rooibos resulted in increased nitric oxide production as well as increased levels of cellular inducible nitric oxide synthase and cyclooxygenase-2, which are typical markers for classically activated macrophages. In contrast, the green extract was devoid of such activity. Using glycated gelatin as a model to mimic diabetic wounds, only the green extract showed potential to reduce cyclooxygenase-2 levels. Considering the role of reactive oxygen species in wound healing, the effects of rooibos on oxidative stress and cell death in human dermal fibroblasts was evaluated. Both fermented and green rooibos decreased cellular reactive oxygen species and attenuated apoptotic/necrotic cell death. Our findings highlight several properties that support the therapeutic potential of rooibos, and demonstrate that green and fermented rooibos present distinctly different properties with regards to their application in wound healing. The proinflammatory nature of fermented rooibos may have therapeutic value for wounds characterised with a delayed initial inflammatory phase, such as early diabetic wounds. The green extract is more suited to wounds burdened with excessive inflammation as it attenuated cyclooxygenase-2 levels and effectively protected fibroblasts against oxidative stress.
Neurogenic Thoracic Outlet Syndrome Caused by Vascular Compression of the Brachial Plexus: A Report of Two Cases
Authors: Hanna Amgad , Bodden Larry , Siebiger Gabriel
Published: February 2018

Thoracic outlet syndrome (TOS) is caused by compression of the brachial plexus and/or subclavian vessels as they pass through the cervicothoracobrachial region, exiting the chest. There are three main types of TOS: neurogenic TOS, arterial TOS, and venous TOS. Neurogenic TOS accounts for approximately 95% of all cases, and it is usually caused by physical trauma (posttraumatic etiology), chronic repetitive motion (functional etiology), or bone or muscle anomalies (congenital etiology). We present two cases in which neurogenic TOS was elicited by vascular compression of the inferior portion of the brachial plexus.
Cerebral Metastasis as First Systemic Event in a Patient with Prostate Adenocarcinoma
Authors: Reinas Rui , Costa Pedro , Baggen Santos Raul , Kitumba Djamel , Furtado Antónia , Espiridião Paulo , Baptista António , Silva Luís , Alves Óscar
Published: February 2018

Prostate adenocarcinoma (PAC) is the second most common malignant tumor in men, and it is usually diagnosed because of its symptoms and/or because of an increase in the value of the prostate-specific antigen (PSA) in asymptomatic patients. The lymph nodes and the bones are the most common sites in which metastases occur, while the brain is a rare site, with metastases occurring in < 2% of the cases, and usually only after the aforementioned sites have been affected. Considering the brain as the only site where a metastasis can occur, the incidence is of 0.15%. We present the case of a 63-year-old male diagnosed with PAC, with a Gleason score of 7 (3+4), who underwent radiotherapy and anti-hormonal therapy in 2012. After biochemical recurrence early in 2015 (PSA: 8 ng/mL), he was re-staged, and the bone and node metastases were excluded. The patient then resumed the hormone therapy with bicalutamide. He was admitted in August 2015 to the emergency department of our institution with headache and behavioral changes. The imaging study revealed a single right temporo-parieto-occipital lesion, which was then resected. The histological analysis confirmed it to be a PAC brain metastasis. The patient went through a cycle of brain radiotherapy, and evolved favorably after one year of follow-up.
Minimally Invasive versus Conventional LVAD-Implantation—An Analysis of the Literature
Authors: Wachter Kristina , Franke Ulrich , Rustenbach Christian , Baumbach Hardy
Published: February 2018

This review aims to provide an overview on recent data to evaluate minimally invasive (MVAD) and conventional (CVAD) left ventricular assist device (LVAD) implantation. A comprehensive literature search of PubMed, Cochrane Library, and ClinicalTrials.gov was conducted up to April 2017. A total of 183 studies were identified; 13 studies met inclusion criteria. The review revealed a trend toward a lower rate of transfusion, and shorter time for cardiopulmonary bypass, as well as a lower 30-day mortality rate for MVAD. This review indicates that there are possible benefits of minimally invasive LVAD implantation, even though the state of literature is poor.
Distal Femoral Physeal Fractures
Authors: Young Ernest , Stans Anthony
Published: February 2018

Physeal fractures of the distal femoral are rare injuries accounting for less than 2% of all physeal injuries, and tend to have a worse prognosis than similar injuries in other locations. This article reviews the evaluation (including imaging), classification, and treatment of these injuries, and discusses their most important complications and their management, including vascular injury and growth arrest.
Trends in Knee Articular Cartilage Treatments: An American Board of Orthopaedic Surgery Database Study
Authors: Westermann Robert , Shamrock Alan , Duchman Kyle , Wolf Brian , Amendola Annunziato , Hancock Kyle
Published: February 2018

This study aims to evaluate the trends in treatment of knee articular cartilage lesions over the past decade using data obtained from the American Board of Orthopaedic Surgery (ABOS) Part II database. The ABOS Part II database was queried from 2004 to 2013 for chondroplasty, microfracture, and osteochondral grafting procedures. All cases were analyzed for patient age and operating surgeon's fellowship training status. Univariate analysis including chi-square test for categorical variables and Student's t-test for continuous variables was performed to determine if any significant changes in practice patterns were present. Linear regression analyses were utilized to examine temporal trends in procedures performed and fellowship training status. From 2004 to 2013, 25,938 procedures addressing articular cartilage lesions from 3,586 surgeons were identified in the ABOS database. 46.8% of these orthopaedic surgeons had completed a 1-year sports medicine fellowship. Sixty-six percent of cartilage surgeries were performed by sports medicine-trained surgeons. The articular cartilage surgical volume decreased from 3,126 cases in 2004 to 1,690 cases in 2013. The most common procedure coded overall was chondroplasty (80.23%) followed by microfracture (21.37%) and osteochondral grafting (2.1%). The mean age of patients undergoing chondroplasty was 46.9 years; this was significantly higher than microfracture (mean age 40.5 years) or osteochondral grafting procedures (mean age 31.6 years), p < 0.0005. The age of all patients undergoing cartilage surgery significantly decreased between 2004 and 2013, p < 0.001. A dramatic decrease in reported chondroplasty volume was observed between 2011 and 2012. Concurrent osteotomies were used in <1% of procedures addressing cartilage injuries, while 65% of patients underwent concurrent meniscectomy. These described trends are most pronounced in surgeons with sports medicine fellowship training. In conclusion, knee articular cartilage surgical volume and patient age have both sharply declined since 2011, a trend driven by sports medicine-trained Part II examinees. This trend correlates with changes in billing and coding practices, as well as improved education from high-level studies.
Recruiting the Digital-Age Applicant: The Impact of Ophthalmology Residency Program Web Presence on Residency Recruitment
Authors: Goerlitz-Jessen Mark , Behunin Nicholas , Montijo Maria , Wilkinson Michael
Published: February 2018

Background The phenomenon of internet dependence has changed the way the rising generation seeks information. This mentality has caused medical students to turn to online resources as they seek information about potential residency training programs. Residency program web presence (PWP) is increasingly important, and may even impact recruitment efforts. Improvement of PWP could enhance programs' recruitment of ideal candidates.

Objectives The purpose of this study is to assess how ophthalmology residency PWP is impacting the residency recruitment process by understanding how it influences applicants' application and rank list choices as well as to identify the contributing factors.

Methods Applicants applying for ophthalmology residency training at Penn State University during the 2015–2016 and 2016–2017 application cycles were surveyed using Research Electronic Data Capture (REDCap). Surveys sought applicants' perspectives with respect to their experiences with PWP and how those experiences shaped their application and rank list decisions.

Results Of 860 applicants, 214 (24.9%) responded, accounting for 17.4% (214/1,228) of all ophthalmology residency applicants during the respective cycles; 72.4% of respondents expressed PWP does impact where they apply, how they form their rank list, or both; 93.4% said websites are an important resource during the application process; 47.2% conveyed interest in programs utilizing social media tools; and 76.5% of respondents felt websites gave sufficient information less than 50% of the time.

Conclusion Ophthalmology PWP does impact resident recruitment. By enhancing program websites and adding social media tools, programs can improve recruitment efforts.
Depressionen und Lebererkrankungen: Die Rolle von Mikrobiom und Inflammation
Authors: Kahl Kai G. , Krüger Tillmann , Eckermann Gabriel , Wedemeyer Heiner
Published: February 2018

Zwischen Depressionen und Lebererkrankungen besteht ein e nger Zusammenhang. Jeder dritte Leberzirrhosepatient und jeder dritte Hepatitispatient ist depressiv. Andererseits entwickelt jeder dritte Patient mit Depressionen im Verlauf seines Lebens eine Alkoholerkrankung, in deren Folge Lebererkrankungen auftreten können. Ein entscheidendes Bindeglied zwischen Lebererkrankungen und Depressionen sind Entzündungsprozesse. Das systemische inflammatorische Milieu ist bei vielen Lebererkrankungen verändert. Außerdem scheint das Mikrobiom und eine erhöhte intestinale Permeabilität des Darms eine große Bedeutung zu haben. Sowohl Depressionen als auch Lebererkrankungen, Alkoholkonsum, Stress und Altersprozesse verschieben das empfindliche Gleichgewicht der Darmmikrobiota und resultieren in einer erhöhten intestinalen Permeabilität. Bakterien und ihre Metabolite wie das Endotoxin Lipopolysaccharid können so in die Blutzirkulation gelangen und sowohl in der Leber als auch im Gehirn über eine Zytokinkaskade Entzündungen auslösen, die wiederum zu Leberveränderungen sowie zu Depressionen, Adipositas und metabolischem Syndrom führen. Daher sollten bei depressiven Erkrankungen Leberentzündungswerte wie auch Marker für die Lebersynthese und Leberentgiftungsfunktion regelmäßig kontrolliert werden. Umgekehrt sollte bei Patienten mit Lebererkrankungen verstärkt auf depressive Symptome geachtet werden, die eine differentielle Therapie unter Berücksichtigung des Stadiums der Lebererkrankung erfordern.
Radiofrequency ablation (RFA) vs. argon plasma coagulation (APC) for the management of gastric antral vascular ectasia (GAVE) in patients with and without cirrhosis: results from a retrospective analysis of a large cohort of patients treated at a single center
Authors: St Romain Paul , Boyd Amanda , Zheng Jiayin , Chow Shein-Chung , Burbridge Rebecca , Wild Daniel
Published: February 2018

Introduction and study aims Gastric antral vascular ectasia (GAVE) is a mucosal abnormality associated with multiple conditions, most notably cirrhosis and systemic sclerosis, that causes indolent gastrointestinal bleeding. It is primarily managed with endoscopic therapy. Traditionally, GAVE is endoscopically ablated using argon plasma coagulation (APC) but radiofrequency ablation (RFA) is emerging as an alternative modality. No prior comparison of the 2 modalities has been published.

We retrospectively compared the effects of GAVE ablation with either RFA, APC or both in the largest cohort of patients thus far presented. We also attempt to discern what effect concomitant cirrhosis has on response to treatment.

Patients and methods After receiving IRB approval, we reviewed our electronic health records to identify all patients who underwent endoscopic evaluation for GAVE between January, 2011 and October, 2016. We compared important variables between APC and RFA, as well as between cirrhosis and non-cirrhosis, using the Chi-square test and the Wilcoxon two-sample test as appropriate.

Results During our study period, 81 patients were endoscopically evaluated for GAVE. 24 patients were treated with APC alone, 28 with RFA alone and 25 patients received both treatment modalities.

APC-treated patients underwent a mean of 2.4 treatment sessions with a mean of 205 days between treatments. RFA-treated patients underwent a mean of 2.3 treatment sessions with a mean of 100 days between treatments.

Hemoglobin values remained stable or increased in all patients during our study period and there were no significant differences in Hgb trend between those treated with APC and those with RFA.

Conclusions RFA and APC were both effective in treating bleeding from GAVE. Though we found subtle differences, patients underwent a similar number of treatment sessions and had similar procedure times and a similar time between sessions no matter the treatment modality used.
Endoscopic necrosectomy of walled-off pancreatic necrosis by large-bore percutaneus metal stent: a new opportunity?
Authors: Tringali Andrea , Vadalà di Prampero Salvatore , Bove Vincenzo , Perri Vincenzo , La Greca Antonio , Pepe Gilda , Cozza Valerio , Costamagna Guido
Published: February 2018

Background and study aims Endoscopic drainage of walled-off pancreatic necrosis (WOPN) is feasible when contact with the gastric or duodenal wall is present; when WOPN cannot be accessed endoscopically, a percutaneous approach can be considered. Percutaneous use of esophageal self-expandable metal stents (SEMS) to establish access to a WOPN cavity was evaluated.
Aortenstenose mit niedrigem Gradienten: Wann ist die Stenose tatsächlich schwer und wer profitiert vom Klappenersatz?
Authors: Minners Jan , Jander Nikolaus
Published: February 2018

Die Aortenstenose mit niedrigem Druckgradienten bezeichnet eine Konstellation, bei der in der echokardiografischen Basisdiagnostik eine Aortenöffnungsfläche (AÖF) < 1,0 cm² und ein mittlerer Druckgradient ≤ 40 mmHg gefunden werden und der Schweregrad somit nicht sicher eingeordnet werden kann. Die neuen Leitlinien und echokardiografischen Empfehlungen stellen erstmals den Schlagvolumenindex (SVI) ins Zentrum der weiteren Differenzierung. Der SVI dient der Entdeckung einer – nicht immer auf den ersten Blick erkennbaren – Pumpfunktionsstörung, die einen relativ niedrigen Druckgradienten bei schwerer Aortenstenose erklären könnte. Die echokardiografische Bestimmung des SVI ist allerdings fehleranfällig und stützt sich auf Parameter, die auch schon für die Bestimmung der AÖF verwendet werden. Deshalb müssen diese Messungen sorgfältig überprüft und der Befund einer hochgradigen Aortenstenose bei erniedrigtem SVI durch Zusatzuntersuchungen bekräftigt werden. Bestätigt sich der Befund einer schweren Stenose, ist auch bei niedrigem Druckgradienten in symptomatischen Patienten – sowohl bei erhaltener als auch reduzierter Ejektionsfraktion – ein Klappenersatz indiziert. Bei Aortenstenose mit niedrigem Druckgradienten und normalem SVI liegt hingegen keine hochgradige Stenose vor und rechtfertigt eine weitere konservative Therapie.
Sekundäre Mitralinsuffizienz: Was kann man durch Intervention oder Operation erreichen?
Authors: Körber Maria , Rudolph Volker
Published: February 2018

Die sekundäre Mitralklappeninsuffizienz (MI) ist eine prognostisch bedeutsame Erkrankung, die häufig bei Patienten mit ischämischer und nicht ischämischer Herzinsuffizienz auftritt. Bisher konnte für die invasive Therapie der sekundären MI kein Überlebensvorteil in kontrollierten Studien nachgewiesen werden und der Grundstein der Therapie ist die leitliniengerechte Herzinsuffizienzbehandlung. Die Empfehlungen zur invasiven Therapie der aktuellen ESC-Guidelines basieren daher vorrangig auf Expertenmeinung sowie auch auf Daten aus Beobachtungsstudien und Registern. Randomisierte Studien fehlen noch. Aufgrund der mittlerweile ausgedehnten Erfahrung mit der interventionellen Therapie mittels MitraClip und deren niedrigem Risiko wurde diese Therapie im Vergleich zu den vorigen Leitlinien aufgewertet und wird aktuell bei Patienten mit nicht niedrigem Operationsrisiko und fehlender Option zur Revaskularisation als Therapieoption angesehen.
Water-separated ion pairs cause the slow dielectric mode of magnesium sulfate solutions
Authors: Mamatkulov Shavkat I. , Rinne Klaus F. , Buchner Richard , Netz Roland R. , Bonthuis Douwe Jan
Published: February 2018

We compare the dielectric spectra of aqueous MgSO4 and Na2SO4 solutions calculated from classical molecular dynamics simulations with experimental data, using an optimized thermodynamically consistent sulfate force field. Both the concentration-dependent shift of the static dielectric constant and the spectral shape match the experimental results very well for Na2SO4 solutions. For MgSO4 solutions, the simulations qualitatively reproduce the experimental observation of a slow mode, the origin of which we trace back to the ion-pair relaxation contribution via spectral decomposition. The radial distribution functions show that Mg2+ and SO42− ions form extensive water-separated—and thus strongly dipolar—ion pairs, the orientational relaxation of which provides a simple physical explanation for the prominent slow dielectric mode in MgSO4 solutions. Remarkably, the Mg2+–SO42− ion-pair relaxation extends all the way into the THz range, which we rationalize by the vibrational relaxation of tightly bound water-separated ion pairs. Thus, the relaxation of divalent ion pairs can give rise to widely separated orientational and vibrational spectroscopic features.
A high-throughput exploration of magnetic materials by using structure predicting methods
Authors: Arapan S. , Nieves P. , Cuesta-López S.
Published: February 2018

We study the capability of a structure predicting method based on genetic/evolutionary algorithm for a high-throughput exploration of magnetic materials. We use the USPEX and VASP codes to predict stable and generate low-energy meta-stable structures for a set of representative magnetic structures comprising intermetallic alloys, oxides, interstitial compounds, and systems containing rare-earths elements, and for both types of ferromagnetic and antiferromagnetic ordering. We have modified the interface between USPEX and VASP codes to improve the performance of structural optimization as well as to perform calculations in a high-throughput manner. We show that exploring the structure phase space with a structure predicting technique reveals large sets of low-energy metastable structures, which not only improve currently exiting databases, but also may provide understanding and solutions to stabilize and synthesize magnetic materials suitable for permanent magnet applications.
An open-chain imaginary-time path-integral sampling approach to the calculation of approximate symmetrized quantum time correlation functions
Authors: Cendagorta Joseph R. , Bačić Zlatko , Tuckerman Mark E.
Published: February 2018

We introduce a scheme for approximating quantum time correlation functions numerically within the Feynman path integral formulation. Starting with the symmetrized version of the correlation function expressed as a discretized path integral, we introduce a change of integration variables often used in the derivation of trajectory-based semiclassical methods. In particular, we transform to sum and difference variables between forward and backward complex-time propagation paths. Once the transformation is performed, the potential energy is expanded in powers of the difference variables, which allows us to perform the integrals over these variables analytically. The manner in which this procedure is carried out results in an open-chain path integral (in the remaining sum variables) with a modified potential that is evaluated using imaginary-time path-integral sampling rather than requiring the generation of a large ensemble of trajectories. Consequently, any number of path integral sampling schemes can be employed to compute the remaining path integral, including Monte Carlo, path-integral molecular dynamics, or enhanced path-integral molecular dynamics. We believe that this approach constitutes a different perspective in semiclassical-type approximations to quantum time correlation functions. Importantly, we argue that our approximation can be systematically improved within a cumulant expansion formalism. We test this approximation on a set of one-dimensional problems that are commonly used to benchmark approximate quantum dynamical schemes. We show that the method is at least as accurate as the popular ring-polymer molecular dynamics technique and linearized semiclassical initial value representation for correlation functions of linear operators in most of these examples and improves the accuracy of correlation functions of nonlinear operators.
Electron trapping in amorphous Al2O3
Authors: Sambuco Salomone L. , Campabadal F. , Faigón A.
Published: February 2018

The electron trapping in MOS capacitors with amorphous Al2O3 as an insulating layer was studied through pulsed capacitance-voltage technique. A positive shift of the voltage value corresponding to a constant capacitance (VC) was observed. The dependences of the voltage instability with the applied bias and the charging time were investigated. Two different contributions could be distinguished: a hysteresis phenomenon observed on each measurement cycle, and a permanent accumulated VC-shift to which each measurement cycle contributes. A physical model based on tunneling transitions between the substrate and defects within the oxide was implemented. From the fitting procedure within the energy range covered in our measurements (1.7–2.7 eV below the conduction band edge), the trap density was found to decrease exponentially with trap energy depth from 3.0 × 1020 cm−3 eV−1 to 9.6 × 1018 cm−3 eV−1, with a uniform spatial distribution within the first 2 nm from the semiconductor interface for the hysteresis traps.
Effect of time-varying flow-shear on the nonlinear stability of the boundary of magnetized toroidal plasmas
Authors: Oh Youngmin , Hwang Hyung Ju , Leconte Michael , Kim Minwoo , Yun Gunsu S.
Published: February 2018

We propose a phenomenological yet general model in a form of extended complex Ginzburg-Landau equation to understand edge-localized modes (ELMs), a class of quasi-periodic fluid instabilities in the boundary of toroidal magnetized high-temperature plasmas. The model reproduces key dynamical features of the ELMs (except the final explosive relaxation stage) observed in the high-confinement state plasmas on the Korea Superconducting Tokamak Advanced Research: quasi-steady states characterized by field-aligned filamentary eigenmodes, transitions between different quasi-steady eigenmodes, and rapid transition to non-modal filamentary structure prior to the relaxation. It is found that the inclusion of time-varying perpendicular sheared flow is crucial for reproducing all of the observed dynamical features.
Simultaneous AFM and fluorescence imaging: A method for aligning an AFM-tip with an excitation beam using a 2D galvanometer
Authors: Moores A. N. , Cadby A. J.
Published: February 2018

Correlative fluorescence and atomic force microscopy (AFM) imaging is a highly attractive technique for use in biological imaging, enabling force and mechanical measurements of particular structures whose locations are known due to the specificity of fluorescence imaging. The ability to perform these two measurements simultaneously (rather than consecutively with post-processing correlation) is highly valuable because it would allow the mechanical properties of a structure to be tracked over time as changes in the sample occur. We present an instrument which allows simultaneous AFM and fluorescence imaging by aligning an incident fluorescence excitation beam with an AFM-tip. Alignment was performed by calibrating a 2D galvanometer present in the excitation beam path and using it to reposition the incident beam. Two programs were developed (one manual and one automated) which correlate sample features between the AFM and fluorescence images, calculating the distance required to translate the incident beam towards the AFM-tip. Using this method, we were able to obtain beam-tip alignment (and therefore field-of-view alignment) from an offset of >15 μm to within one micron in two iterations of the program. With the program running alongside data acquisition for real-time feedback between AFM and optical images, this offset was maintained over a time period of several hours. Not only does this eliminate the need to image large areas with both techniques to ensure that fields-of-view overlap, but it also raises the possibility of using this instrument for tip-enhanced fluorescence applications, a technique in which super-resolution images have previously been achieved.
On the optical polarization properties of semipolar (202¯1) and (202¯1¯) InGaN/GaN quantum wells
Authors: Mounir Christian , Koslow Ingrid L. , Wernicke Tim , Kneissl Michael , Kuritzky Leah Y. , Adamski Nicholas L. , Oh Sang Ho , Pynn Christopher D. , DenBaars Steven P. , Nakamura Shuji , Speck James S. , Schwarz Ulrich T.
Published: February 2018

In the framework of k·p-theory, semipolar (202¯1) and (202¯1¯) InGaN/GaN quantum wells (QWs) have equivalent band structures and are expected to have identical optical polarization properties. However, (202¯1) QWs consistently exhibit a lower degree of linear polarization (DLP) than (202¯1¯) QWs. To understand this peculiarity, we investigate the optical properties of (202¯1) and (202¯1¯) InGaN/GaN single QW light-emitting diodes (LEDs) via resonant polarization-resolved photoluminescence microscopy. LEDs were grown on bulk substrates by metal organic vapor phase epitaxy with different indium concentrations resulting in emission wavelengths between 442 nm and 491 nm. We discuss the origin of their DLP via k·p band structure calculations. An analytical expression to estimate the DLP in the Boltzmann-regime is proposed. Measurements of the DLP at 10 K and 300 K are compared to m-plane LEDs and highlight several discrepancies with calculations. We observe a strong correlation between DLPs and spectral widths, which indicates that inhomogeneous broadening affects the optical polarization properties. Considering indium content fluctuations, QW thickness fluctuations, and the localization length of charge carriers, we argue that different broadenings apply to each subband and introduce a formalism using effective masses to account for inhomogeneous broadening in the calculation of the DLP. We conclude that the different DLP of (202¯1) and (202¯1¯) QWs might be related to different effective broadenings of their valence subbands induced by the rougher upper QW interface in (202¯1), by the larger sensitivity of holes to this upper interface due to the polarization field in (202¯1), and/or by the different degrees of localization of holes.
Electrical characterization of the temperature dependence in CdTe/CdS heterojunctions deposited in-situ by pulsed laser deposition
Authors: Avila-Avendano Jesus , Quevedo-Lopez Manuel , Young Chadwin
Published: February 2018

The I-V and C-V characteristics of CdTe/CdS heterojunctions deposited in-situ by Pulsed Laser Deposition (PLD) were evaluated. In-situ deposition enables the study of the CdTe/CdS interface by avoiding potential impurities at the surface and interface as a consequence of exposure to air. The I-V and C-V characteristics of the resulting junctions were obtained at different temperatures, ranging from room temperature to 150 °C, where the saturation current (from 10−8 to 10−4 A/cm2), ideality factor (between 1 and 2), series resistance (from 102 to 105 Ω), built-in potential (0.66–0.7 V), rectification factor (∼106), and carrier concentration (∼1016 cm−3) were obtained. The current–voltage temperature dependence study indicates that thermionic emission is the main transport mechanism at the CdTe/CdS interface. This study also demonstrated that the built-in potential (Vbi) calculated using a thermionic emission model is more accurate than that calculated using C-V extrapolation since C-V plots showed a Vbi shift as a function of frequency. Although CdTe/CdS is widely used for photovoltaic applications, the parameters evaluated in this work indicate that CdTe/CdS heterojunctions could be used as rectifying diodes and junction field effect transistors (JFETs). JFETs require a low PN diode saturation current, as demonstrated for the CdTe/CdS junction studied here.
Experimental study on the stability of laminar flow in a channel with streamwise and oblique riblets
Authors: Ho Huy Quang , Asai Masahito
Published: February 2018

The influence of riblets on the streamwise growth of Tollmien-Schlichting (T-S) waves was examined experimentally in a channel flow. Riblets having triangular ridges and trapezoidal valleys, with a height-to-width ratio of 0.5, were glued on the upper channel wall. The ridge spacing was 11% of the channel half-depth which gave a non-dimensional wavenumber of 57. In addition to the effects of streamwise riblets, the effects of oblique riblets whose direction was inclined to the streamwise direction were examined to see how the instability characteristics depended on the riblet alignment. The result showed that the critical Reynolds number for the linear instability Recr was reduced to about 4200 by the streamwise riblets, while the wavenumber of the T-S wave was little influenced by the presence of riblets. For the present small riblets, the parabolic velocity profile was modified only in the vicinity of the ribbed surface, with the virtual wall position located inside the riblets. Such a local and small change in the velocity profile enhanced the instability of the plane Poiseuille flow appreciably. When the riblets were inclined to the streamwise direction, Recr increased as the oblique angle of riblets ϕ was increased. For ϕ ≥ 45°, the riblets had no noticeable influence on the structure of the T-S wave and the growth rates were the same as those in the smooth-wall case.
Cyanographone and isocyanographone — Two asymmetrically functionalized graphene pseudohalides and their potential use in chemical sensing
Authors: Marsoner Steinkasserer Lukas Eugen , Pohl Vincent , Paulus Beate
Published: February 2018

Graphene pseudohalides are natural candidates for use in molecular sensing due to their greater chemical activity as compared to both graphene halides and pristine graphene. Though their study is still in its infancy, being hindered until recently by the unavailability of both selective and efficient procedures for their synthesis, they promise to considerably widen the application potential of chemically modified graphenes. Herein, we employ van der Waals density functional theory to study the structural and electronic properties of two selected graphene pseudohalides, namely, cyanographone and isocyanographone and investigate the potential use of the latter as a chemical sensor via electron transport calculations.
Topologically protected bound states in one-dimensional Floquet acoustic waveguide systems
Authors: Peng Yu-Gui , Geng Zhi-Guo , Zhu Xue-Feng
Published: February 2018

Topological manipulation of sound has recently been a hot spot in acoustics due to the fascinating property of defect immune transport. To the best of our knowledge, the studies on one-dimensional (1D) topological acoustic systems hitherto mainly focus on the case of the Su-Schrieffer-Heeger model. Here, we show that topologically protected bound states may also exist in 1D periodically modulated acoustic waveguide systems, viz., 1D Floquet topological insulators. The results show that tuning the coupling strength in a waveguide lattice could trigger topological phase transition, which gives rise to topologically protected interface states as we put together two waveguide lattices featured with different topological phases or winding numbers. However, for the combined lattice, input at the waveguides other than the interfacial ones will excite bulk states. We have further verified the robustness of interface bound states against the variation of coupling strengths between the two distinct waveguide lattices. This work extends the scope of topological acoustics and may promote potential applications for acoustic devices with topological functionalities.
Classification of conductance traces with recurrent neural networks
Authors: Lauritzen Kasper P. , Magyarkuti András , Balogh Zoltán , Halbritter András , Solomon Gemma C.
Published: February 2018

We present a new automated method for structural classification of the traces obtained in break junction experiments. Using recurrent neural networks trained on the traces of minimal cross-sectional area in molecular dynamics simulations, we successfully separate the traces into two classes: point contact or nanowire. This is done without any assumptions about the expected features of each class. The trained neural network is applied to experimental break junction conductance traces, and it separates the classes as well as the previously used experimental methods. The effect of using partial conductance traces is explored, and we show that the method performs equally well using full or partial traces (as long as the trace just prior to breaking is included). When only the initial part of the trace is included, the results are still better than random chance. Finally, we show that the neural network classification method can be used to classify experimental conductance traces without using simulated results for training, but instead training the network on a few representative experimental traces. This offers a tool to recognize some characteristic motifs of the traces, which can be hard to find by simple data selection algorithms.
Absolute cross section measurements for the scattering of low- and intermediate-energy electrons from PF3. II. Inelastic scattering of vibrational and electronic excitations
Authors: Hishiyama N. , Hoshino M. , Blanco F. , García G. , Tanaka H.
Published: February 2018

As a sequel paper to our study of the elastic scattering for electron collisions with phosphorus trifluoride, PF3 molecules, we report absolute inelastic differential and integral cross sections (DCS and ICS) of vibrational excitations for the compound fundamental vibrational modes v13 (v1 + v3), v24 (v2 + v4), and their sum in the impact energy range of 2.0–10 eV and over a scattering angle range of 20°–130°. The measured angular distributions of scattered electron intensities for the present inelastic scattering are normalized to the elastic peak intensity corresponding to the DCSs of He. These vibrational excitation measurements demonstrate the presence of resonances around 2 eV and also around 6–10 eV. In addition, a generalized oscillator strength analysis is applied to derive oscillator strength f0-values and (unscaled Born) ICSs from the corresponding DCSs measured for the low-lying optically allowed 8a1−1 → 7e (σ*) excitation band, which is assigned as the Jahn-Teller splitting and 8a1−1 → 4s Rydberg transition at impact energies of 100, 200, and 300 eV, over a scattering angle range of 1.0°–15°. The f0-values obtained in the present study are compared with the results of previous photoabsorption and pseudo-optical measurements. The unscaled Born ICSs are compared with the binary-encounter f-scaled Born ICSs estimated over a wide impact energy region from the excitation thresholds.
Structural effects in the interstitial solid solution system (La,Ce)(Fe,Si)13Cx-H: Correlation with hydrogenation kinetics
Authors: Hai X. , Porcher F. , Mayer C. , Miraglia S.
Published: February 2018

Steady state and in-situ neutron powder diffraction on selected compositions of the magneto-caloric (La,Ce)(Fe,Si)13CxHy compounds has been used to locate the sites accommodated by the interstitial species and to reveal the structural modifications (breathing) that occur upon metal substitution and/or interstitial insertion. The latter type of measurement in which the sequential filling of interstitial sites is followed allows one to extract some useful hydrogenation kinetics data. This structural investigation has allowed to precise the deformations undergone by the complex metallic alloys La(Fe,Si)13 when subjected to light interstitial insertion or rare earth substitution at the cation site of the NaZn13-structure type. We attempt to correlate hydrogenation kinetics variations (depression or enhancement of the hydrogen absorption rate) with a particular inhomogeneous cell variation (breathing) and bonding of the NaZn13 structure-type.
Finding the best density functional approximation to describe interaction energies and structures of ionic liquids in molecular dynamics studies
Authors: Perlt Eva , Ray Promit , Hansen Andreas , Malberg Friedrich , Grimme Stefan , Kirchner Barbara
Published: February 2018

Ionic liquids raise interesting but complicated questions for theoretical investigations due to the fact that a number of different inter-molecular interactions, e.g., hydrogen bonding, long-range Coulomb interactions, and dispersion interactions, need to be described properly. Here, we present a detailed study on the ionic liquids ethylammonium nitrate and 1-ethyl-3-methylimidazolium acetate, in which we compare different dispersion corrected density functional approximations to accurate local coupled cluster data in static calculations on ionic liquid clusters. The efficient new composite method B97-3c is tested and has been implemented in CP2K for future studies. Furthermore, tight-binding based approaches which may be used in large scale simulations are assessed. Subsequently, ab initio as well as classical molecular dynamics simulations are conducted and structural analyses are presented in order to shed light on the different short- and long-range structural patterns depending on the method and the system size considered in the simulation. Our results indicate the presence of strong hydrogen bonds in ionic liquids as well as the aggregation of alkyl side chains due to dispersion interactions.
The effect of shear flow and the density gradient on the Weibel instability growth rate in the dense plasma
Authors: Amininasab S. , Sadighi-Bonabi R. , Khodadadi Azadboni F.
Published: February 2018

Shear stress effect has been often neglected in calculation of the Weibel instability growth rate in laser-plasma interactions. In the present work, the role of the shear stress in the Weibel instability growth rate in the dense plasma with density gradient is explored. By increasing the density gradient, the shear stress threshold is increasing and the range of the propagation angles of growing modes is limited. Therefore, by increasing steps of the density gradient plasma near the relativistic electron beam-emitting region, the Weibel instability occurs at a higher stress flow. Calculations show that the minimum value of the stress rate threshold for linear polarization is greater than that of circular polarization. The Wiebel instability growth rate for linear polarization is 18.3 times circular polarization. One sees that for increasing stress and density gradient effects, there are smaller maximal growth rates for the range of the propagation angles of growing modes π2<θmin<π and 3π2<θmin<2π in circular polarized plasma and for kcωp<4 in linear polarized plasma. Therefore, the shear stress and density gradient tend to stabilize the Weibel instability for kcωp<4 in linear polarized plasma. Also, the shear stress and density gradient tend to stabilize the Weibel instability for the range of the propagation angles of growing modes π2<θmin<π and 3π2<θmin<2π in circular polarized plasma.
Microstructure evolution determined by the crystalline phases competition in self-assembled WO3-BiVO4 hetero nanostructures
Authors: Song Haili , Li Chao , Nguyen Van Chien , Dong Wenxia , Qi Ruijuan , Zhang Yuanyuan , Huang Rong , Chu Ying-Hao , Duan Chun-Gang
Published: February 2018

A series of self-assembled WO3–BiVO4 nanostructured thin films were grown on the (001) yttria-stabilized zirconia (YSZ) substrate at the substrate temperatures of 400 °C, 500 °C, 550 °C, 600 °C, 650 °C and 700 °C by a pulsed laser deposition method. The microstructures including crystalline phases, epitaxial relationships, surface morphologies and interface structures were investigated by a combination of x-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. The sample grown at 400 °C was amorphous due to the low driving forces for nucleation and diffusion. For the samples made at 500 °C, 550 °C and 600 °C, the monoclinic BiVO4 matrix epitaxially grew on YSZ, forming the matrix, where the WO3 nanopillars were embedded in with a specific orientation relationship among BiVO4, WO3 and YSZ. However, in thin films deposited at 650 °C and 700 °C, the WO3 grains randomly grew on the YSZ substrate, which dominated the microstructures of the resultant thin films. Quantitative analyses of the microstructures revealed that the lateral grain sizes of BiVO4 and WO3 increased and the volume fraction of BiVO4 in the thin films decreased with the increase of the deposition temperature. A three-regime growth mechanism of the WO3–BiVO4 composite thin film was proposed based on the growth dynamics determined by the competition between BiVO4 and WO3.