bluuebunny/crossref_metadata_2025 huggingface dataset:
Die Facharztprüfung Innere Medizin: Eine qualitative und quantitative Analyse von Gedächtnisprotokollen
Authors: Beckers Marc Aurelio , Braun Leah T. , Epstein Nurith , Fischer Martin R. , Schmidmaier Ralf
Published: September 2019

Einleitung Die Facharztprüfung berechtigt zur selbstständigen Berufsausübung und ist von besonderer Bedeutung für die Qualität der ärztlichen Versorgung. Sie soll die Inhalte der Weiterbildungsordnung abdecken. Über die tatsächlich abgefragten Inhalte der Prüfung ist wenig bekannt. In dieser Studie soll die Frage beantwortet werden, welche inhaltlichen und strukturellen Charakteristika Facharztprüfungen der Inneren Medizin in Deutschland haben.

Methoden 100 Gedächtnisprotokolle von bundesweiten Facharztprüfungen aus den Jahren 2013–2016 wurden hinsichtlich ihrer inhaltlichen Schwerpunkte sowie der Fragetypen quantitativ erfasst und deskriptiv ausgewertet. Die Ergebnisse wurden mit den Blueprints der Facharztprüfungen der Schweiz sowie der USA verglichen.

Ergebnisse In jeder Prüfung werden durchschnittlich 27 (SD = 10) Fragen gestellt; diese lassen sich in 3 Kategorien einordnen: (1) themenbezogene Einzelfragen, (2) fallbezogene Fragen, (3) auf diagnostische Verfahren ausgerichtete Fragen anhand von Medien. Die am häufigsten abgefragten internistischen Themenschwerpunkte sind Kardiologie, Gastroenterologie (jeweils 17 %) und Endokrinologie (11 %). Bei 50 % der Fragen musste Wissen reproduziert, bei den anderen 50 % Konzepte oder Prozeduren verstanden und angewendet werden. Beim Vergleich mit amerikanischen und schweizerischen Blueprints wurde eine ähnliche prozentuale Aufteilung der Fragen zu Themengebieten gefunden. In Bezug auf den amerikanischen Blueprint fällt auf, dass mehr Fragen aus anderen Facharztbereichen gestellt werden als in Deutschland. Beim schweizerischen Blueprint wird ein großes Spektrum an fächerübergreifenden Aspekten wie Ethik, Prävention und Wirtschaft abgefragt, die in der deutschen Facharztprüfung kein Prüfungsgegenstand sind.

Diskussion In der mündlichen Facharztprüfung Innere Medizin in Deutschland werden ebenso viele Themengebiete wie in ausländischen Facharztprüfungen abgeprüft. Allerdings ist die Varianz zwischen den einzelnen Prüfungen relativ groß. Eine Standardisierung der Prüfung wäre wichtig, um gleiche Prüfungsbedingungen für alle Kandidaten zu schaffen.
Plasma Secretagogin is Increased in Individuals with Glucose Dysregulation
Authors: Yang Chao , Qu Hua , Zhao Xiaolan , Hu Yingru , Xiong Jiayao , Jiang Xianshu , Chen Yanmei , Li Zhiyong
Published: September 2019

Objective Secretagogin, a Ca2+ binding protein, is one of the most abundant proteins in pancreatic β-cells and is critical for maintaining the structural integrity and signaling competence of β-cells. This study seeks to assess the concentrations of plasma secretagogin in participants with prediabetes (pre-DM) and newly diagnosed type 2 diabetes (T2DM) and to explore its relationship to parameters of glucose and lipid metabolism, first-phase insulin secretion, insulin resistance and pancreatic β-cell function.

Materials and Methods A total of 126 eligible subjects were divided into three groups: a normal glucose tolerance (NGT, n=45), a pre-DM (n=30), and a T2DM (n=51) group. An intravenous glucose tolerance test (IVGTT) was performed, and clinical and biochemical parameters were measured for all subjects.

Results Plasma secretagogin levels were significantly higher in both pre-DM and T2DM patients compared with NGT subjects and were highest in the T2DM group. Correlation analysis showed that plasma secretagogin levels were positively correlated with fasting plasma glucose, postchallenge plasma glucose (2hPG), HbA1c and body mass index (BMI) but were not correlated with waist-hip ratio, blood pressure, lipid profiles, fasting serum insulin, homeostasis model assessment for insulin resistance, homeostasis model assessment for β-cell function and first-phase insulin secretion indicators. Multiple logistic regression analysis revealed that 2hPG and BMI were independent predictors for elevation of plasma secretagogin concentrations.

Conclusions Increased circulating secretagogin might be a molecular predictor for early diagnosis of diabetes. Further studies are needed to confirm this finding and explore the role of secretagogin in obesity.
Clinical and Molecular Characteristics of GNAS Inactivation Disorders Observed in 18 Korean Patients
Authors: Han Sa Ra , Lee Young Ah , Shin Choong-Ho , Yang Sei-Won , Lim Byung Chan , Cho Tae-Joon , Ko Jung Min
Published: September 2019

Background The GNAS gene on chromosome 20q13.3 is a complex, imprinted locus regulated in a tissue-specific manner. GNAS inactivation disorders are a heterogeneous group of rare disorders caused by mutations and methylation defects. These are divided into pseudohypoparathyroidism (PHP) types 1A and 1B, pseudo-pseudohypoparathyroidism (PPHP), and progressive osseous heteroplasia (POH), depending on the presence or absence of hormone resistance, Albright’s hereditary osteodystrophy (AHO), and ectopic ossification.

Methods This study analyzed the clinical characteristics and molecular genetic backgrounds of 18 Korean patients from 16 families with a genetically confirmed GNAS defect. Auxological parameters, AHO phenotypes, types of hormonal resistance, family history, and molecular genetic disturbances were reviewed retrospectively.

Results Nine (90%) patients with PHP1A showed resistance to parathyroid hormone (PTH) and all patients showed elevated thyroid-stimulating hormone (TSH) levels at diagnosis. Eight (80%) patients were managed with levothyroxine supplementation. Three of six patients with PHP1B had elevated TSH levels, but none of whom needed levothyroxine medication. AHO features were absent in PHP1B. Patients with PPHP and POH did not show any hormone resistance, and both of them were born as small for gestational age. Among the 11 families with PHP1A, PPHP, and POH, eight different (three novel) mutations in the GNAS gene were identified. Among the six patients with PHP1B, two were sporadic cases and four showed isolated loss of methylation at GNAS A/B:TSS-DMR.

Conclusions Clinical and molecular characteristics of Korean patients with GNAS inactivation disorders were described in this study. Also, we reaffirmed heterogeneity of PHP, contributing to further accumulation and expansion of current knowledge of this complex disease.
Antinociceptive and Anti-Inflammatory Effects of Bixin, a Carotenoid Extracted from the Seeds of Bixa orellana
Authors: Pacheco Samanta Daliana Golin , Gasparin Alexia Thamara , Jesus Carlos Henrique Alves , Sotomaior Bruna Bittencourt , Ventura Ana Clara Sans Salomão Brunow , Redivo Daiany Darlly Belo , Cabrini Daniela de Almeida , Gaspari Dias Josiane de Fátima , Miguel Marilis Dallarmi , Miguel Obdulio Gomes , da Cunha Joice Maria
Published: September 2019

Bixin is the main natural apocarotenoid extracted from the seeds of Bixa orellana, widely used as a cosmetic and textile colorant. Despite the description of several pharmacological properties of B. orellana extracts, little has been studied regarding the pharmacological properties of bixin. Then we aimed to investigate the potential anti-inflammatory and antinociceptive effect of bixin in preclinical models of inflammation and acute pain. The anti-inflammatory activity of bixin (15 or 30 mg/kg, orally) was determined using carrageenan-induced paw edema and the myeloperoxidase (MPO) activity in male Wistar rats. The antinociceptive effect of bixin was assessed in the formalin and hot plate tests in rats (at same doses) and in the acetic acid-induced writhing test in Swiss albino male mice (at doses of 27 or 53 mg/kg). General locomotor activity was evaluated in the open field test. Only the higher dose of bixin significantly decreased the carrageenan-induced paw edema and the MPO activity and increased the latency time in the hot plate. Both doses of bixin significantly reduced the number of flinches in both phases of the formalin test and the number of acetic acid-induced writhings without changing the locomotor performance in the open field test. This study validates the use of bixin as an anti-inflammatory trough mechanism related to the reduction of neutrophil migration. Furthermore, this is the first report showing the antinociceptive property of bixin, which does not appear to be related to the sedative effect. Further studies are necessary to characterize the mechanisms involved in these effects.
Reduced Compensatory β-Cell Proliferation in Nfatc3-Deficient Mice Fed on High-Fat Diet
Authors: Hu Li , He Fengli , Luo Yan , Luo Hairong , Hai Luo , Li Yabin , Zhou Zhiguang , Liu Feng , Dai Yan-Shan
Published: September 2019

Background High-fat-diet induces pancreatic β-cell compensatory proliferation, and impairments in pancreatic β-cell proliferation and function can lead to defects in insulin secretion and diabetes. NFATc3 is important for HFD-induced adipose tissue inflammation. But it is unknown whether NFATc3 is required for β cell compensatory growth in mice fed with HFD.

Methods NFATc3 mRNA and protein expression levels were quantified by RT-qPCR and Western blotting, respectively, in pancreatic islets of WT mice fed on HFD for 12–20 weeks. Adenoviral-mediated overexpression of NFATc3 were conducted in Min6 cells and cultured primary mouse islets. NFATc3-/- mice and WT control mice were fed with HFD and metabolic and functional parameters were measured.

Results We observed that the NFATc3 expression level was reduced in the islets of high-fat-diet (HFD)-fed mice. Adenovirus-mediated overexpression of NFATc3 enhanced glucose-stimulated insulin secretion and β-cell gene expression in cultured primary mouse islets. Nfatc3-/- mice initially developed similar glucose tolerance at 2–4 weeks after HFD feeding than HFD-fed WT mice, but Nfatc3-/- mice developed improved glucose tolerance and insulin sensitivity after 8 weeks of HFD feeding compared to Nfatc3+/+fed with HFD. Furthermore, Nfatc3-/- mice on HFD exhibited decreased β-cell mass and reduced expression of genes important for β-cell proliferation and function compared to Nfatc3+/+mice on HFD.

Conclusions The findings suggested that NFATc3 plays a role in maintaining the pancreatic β-cell compensatory growth and gene expression in response to obesity.
Cyclopropanation Reactions of Semi-stabilized and Non-stabilized Diazo Compounds
Authors: Allouche Emmanuelle M. D. , Charette André B.
Published: September 2019

The cyclopropane ring is present in a large number of bio­active molecules as its incorporation often greatly alters their physiochemical properties. The synthesis of such motif is therefore of interest. Diazo compounds are versatile and powerful reagents that can be used in a broad range of reactions, including cyclopropanation processes. However, in case of unstable diazo reagents such as the donor-substituted­ variants, their inherent toxicity and instability have hampered their effective synthesis and utilization. Herein, we report the recent­ advances devoted to the safe and facile production of these potentially hazardous species and their subsequent application in cyclopropanation reactions, allowing the synthesis of more complex cyclopropylated motifs.

1 Introduction

2 Halomethylmetal-Mediated Cyclopropanations

3 Cyclopropanations through Metallic- or Free Carbenes

3.1 Transition-Metal-Catalyzed Decomposition of Diazo Compounds

3.2 Metal-Free Decomposition of Diazo Compounds

4 Michael Induced Ring Closure (MIRC) Reactions

4.1 Sulfur Ylides

4.2 1,3-Dipolar Cycloadditions

5 Conclusion
Recent Developments in the Synthesis of 1,2,5-Thiadiazoles and 2,1,3-Benzothiadiazoles
Authors: Rakitin Oleg A.
Published: September 2019

The fast-growing interest in 1,2,5-thiadiazoles and their fused analogues including 2,1,3-benzothiadiazoles in recent years as important compounds in materials science and biomedicine has led to great progress in the synthesis of these heterocyclic systems. In this short review, the development of known procedures together with novel reactions is covered. New starting materials, unknown and unexpected transformations for the construction of the thiadiazole ring are emphasized.

1 Introduction

2 Synthesis of Monocyclic 1,2,5-Thiadiazoles

2.1 From 1,2-Diamines, vic-Dioximes and Related Compounds

2.2 From Alkyl Aryl (Hetaryl) Ketoximes and Tetrasulfur Tetranitride

2.3 By Condensation Reactions

2.4 From Other Heterocycles

3 Synthesis of Fused 1,2,5-Thiadiazoles

3.1 From ortho-Phenylenediamines and Related Compounds

3.2 From ortho-Aminonitroso and ortho-Aminonitro Derivatives

3.3 By Condensation Reactions

3.4 By Chalcogen Exchange in 1,2,5-Oxa- and 1,2,5-Selenadiazoles

3.5 Miscellaneous Methods

4 Conclusions
Pharmacological Treatment for Symptomatic Adenomyosis: A Systematic Review
Authors: Benetti-Pinto Cristina Laguna , Mira Ticiana Aparecida Alves de , Yela Daniela Angerame , Teatin-Juliato Cassia Raquel , Brito Luiz Gustavo Oliveira
Published: September 2019

Objective To assess the efficacy of non-surgical treatment for adenomyosis.

Data Sources A search was performed by two authors in the Pubmed, Scopus, and Scielo databases and in the grey literature from inception to March 2018, with no language restriction.

Selection of Studies We have included prospective randomized studies for treating symptomatic women with adenomyosis (abnormal uterine bleeding and/or pelvic pain) diagnosed by ultrasound or magnetic resonance imaging.

Data Collection Studies were primarily selected by title and abstract. The articles that were eligible for inclusion were evaluated in their entirety, and their data was extracted for further processing and analysis.

Data Synthesis From 567 retrieved records only 5 remained for analysis. The intervention groups were: levonorgestrel intrauterine system (LNG-IUS)(n = 2), dienogest (n = 2), and letrozole (n = 1). Levonorgestrel intrauterine system was effective to control bleeding when compared to hysterectomy or combined oral contraceptives (COCs). One study assessed chronic pelvic pain and reported that LNG-IUS was superior to COC to reduce symptoms. Regarding dienogest, it was efficient to reduce pelvic pain when compared to placebo or goserelin, but less effective to control bleeding than gonadotropin-releasing hormone (GnRH) analog. Letrozole was as efficient as GnRH analog to relieve dysmenorrhea and dyspareunia, but not for chronic pelvic pain. Reduction of uterine volume was seen with aromatase inhibitors, GnRH analog, and LGN-IUD.

Conclusion Levonorgestrel intrauterine system and dienogest have significantly improved the control of bleeding and pelvic pain, respectively, in women with adenomyosis. However, there is insufficient data from the retrieved studies to endorse each medication for this disease. Further randomized control tests (RCTs) are needed to address pharmacological treatment of adenomyosis.
Functional and Degenerative Mitral Regurgitation: One Ring Fits All?
Authors: Sideris Konstantinos , Boehm Johannes , Voss Bernhard , Guenther Thomas , Lange Ruediger S. , Guenzinger Ralf
Published: September 2019

Background Three-dimensional saddle-shaped annuloplasty rings have been shown to create a larger surface of leaflet coaptation in mitral valve repair (MVR) for functional mitral regurgitation (FMR) and degenerative mitral regurgitation (DMR) which may increase repair durability. For the first time, this study reports mid-term results after MVR for DMR and FMR using a rigid three-dimensional ring (Profile 3D, Medtronic).

Methods Between June 2009 and June 2012, 369 patients with DMR (n = 326) or FMR (n = 43) underwent MVR (mean age 62.3 ± 12.6 years). A total of 205 patients (55.6%) underwent isolated MVR and 164 patients (44.4%) a combined procedure. Follow-up examinations were performed in 94.9% (mean 4.9 ± 0.9 years). Echocardiographic assessment was complete in 93.2% (mean 4.3 ± 1.2 years).

Results The 30-day mortality was 1.5% (5/326) for DMR (1.5% for isolated and 1.6% for combined procedures) and 9.3% (4/43) for FMR (0% for isolated and 10.5% for combined procedures). Survival at 6 years was 92.1 ± 1.9% for DMR (92.9 ± 2.6% for isolated and 90.7 ± 2.7% for combined procedures) and 66.4 ± 7.9% for FMR (80.0 ± 17.9% for isolated and 63.7 ± 8.9% for combined procedures). Cumulative risk for mitral valve-related reoperation at 6 years was 0% for FMR and 7.1 ± 1.5% for DMR. At echocardiographic follow-up, one patient presented with mitral regurgitation (MR) more than moderate. The only predictor of recurrent MR after MVR for DMR was residual mild MR at discharge.

Conclusion Repair of FMR with the three-dimensional Profile 3D annuloplasty ring shows excellent mid-term results with regard to recurrence of MR. In cases of DMR, the results are conforming to the current literature.
Resultados funcionais e radiológicos do tratamento cirúrgico da luxação acromioclavicular aguda com âncoras e fixação clavículo-escapular
Authors: Mendes Júnior Adriano Fernando , Mota Neto José da , Dias Darlan Malba , Simoni Leandro Furtado de , Loures Elmano de Araújo , Labronici Pedro José
Published: September 2019

Objetivo Avaliar os resultados clínicos, radiológicos, e funcionais do tratamento cirúrgico da luxação acromioclavicular aguda, utilizando a técnica de sindesmopexia coracoclavicular com duas âncoras metálicas, fixação temporária clavículo-escapular, e transferência do ligamento coracoacromial.

Métodos Estudo observacional longitudinal com trinta pacientes com diagnóstico de luxação acromioclavicular aguda submetidos à cirurgia, com seguimento mínimo de seis meses, avaliados clínica, radiograficamente, e pelos escores de University of California at Los Angeles (UCLA), Disabilities of the Arm, Shoulder and Hand (DASH) e Constant-Murley.

Resultados Os valores médios dos escores foram: UCLA = 32; DASH = 11,21; e Constant-Murley = 86,93, com resultados satisfatórios acima de 80%. Os resultados insatisfatórios foram relacionados à dor acromioclavicular, a testes de impacto subacromial positivos, e aos pacientes de faixa etária mais elevada (p < 0,05). Radiologicamente, valores maiores em razão da distância coracoclavicular do ombro operado, comparado com o ombro normal, foram relacionados a piores resultados, embora sem significância estatística. Não foi observada associação entre os resultados dos escores funcionais e as variáveis grau da lesão, transferência do ligamento coracoacromial, impressão clínica de perda de redução, e discinesia escapulo-torácica.

Conclusão A técnica utilizada propicia uma fixação eficiente, com alto índice de satisfação segundo os escores de UCLA, Constant-Murley e DASH. Observou-se baixo índice de complicações apesar da frequência elevada de subluxação acromioclavicular radiológica residual.
Oil pipelines and food sovereignty: threat to health equity for Indigenous communities
Authors: Jonasson Michael E. , Spiegel Samuel J. , Thomas Sarah , Yassi Annalee , Wittman Hannah , Takaro Tim , Afshari Reza , Markwick Michael , Spiegel Jerry M.
Published: September 2019

Energy projects may profoundly impact Indigenous peoples. We consider effects of Canada’s proposed Trans Mountain oil pipeline expansion on the health and food sovereignty of the Tsleil-Waututh Nation (TWN) through contamination and impeded access to uncontaminated traditional foods. Federal monitoring and TWN documentation show elevated shellfish biotoxin levels in TWN’s traditional territory near the terminus where crude oil is piped. Although TWN restoration work has re-opened some shellfish-harvesting sites, pipeline expansion stands to increase health risk directly through rising bioaccumulating chemical toxins as well as through increased hazardous biotoxins. Climate change from increased fossil fuel use, expected via pipeline expansion, also threatens to increase algae blooms through higher temperature and nutrient loading. As the environmental impact assessment process failed to effectively consider these local health concerns in addition to larger impacts of climate change, new assessment is needed attending to linked issues of equity, sustainability and Indigenous food sovereignty.
Some results on standing wave solutions for a class of quasilinear Schrödinger equations
Authors: Chen Jianhua , Huang Xianjiu , Cheng Bitao , Zhu Chuanxi
Published: September 2019

In this paper, we study the following quasilinear Schrödinger equations −Δu+V(x)u+κ2Δ(u2)u=f(u)+μ|u|2*−2u,  x∈RN, where N ≥ 3, κ > 0, μ ≥ 0, and V:RN→R satisfy suitable assumptions. First, by using a change of variable and some new skills, we obtain the ground states for this problem with subcritical growth via the Pohozaev manifold. Second, we establish the existence of ground state solutions with critical growth via L∞estimates, which use the method developed by Brezis and Nirenberg [Commun. Pure Appl. Math. 36, 437–477 (1983)] and Jeanjean [Proc. R. Soc. Edinburgh, Sect A. 129, 787–809 (1999)]. Moreover, we give the nonexistence of positive solutions for this problem, where the nonlinear term allow general asymptotically linear growth. Our results extend and supplement the results obtained by Severo et al. [J. Differ. Equations 263, 3550–3580 (2017)], Xu and Chen [J. Differ. Equations 265, 4417–4441 (2018)], and Lehrer and Maia [J. Funct. Anal. 266, 213–246 (2014)] and some other related literature.
Electronic structure and transport in amorphous metal oxide and amorphous metal oxynitride semiconductors
Authors: Srivastava Juhi , Nahas Suhas , Bhowmick Somnath , Gaur Anshu
Published: September 2019

Recently, amorphous oxide semiconductors have gained significant interest due to their low-temperature processability, high mobility, and high areal uniformity for display backplanes and other large area applications. A multication amorphous oxide, amorphous indium gallium zinc oxide (a-IGZO), has been extensively researched and is now being used in commercial applications. It has been proposed that, in a-IGZO semiconductors, overlapping In-5s orbitals form the conduction path and the carrier mobility is limited due to the presence of multiple cations, which creates a potential barrier for the electronic transport. A multianion approach toward amorphous semiconductors has been suggested to overcome this limitation, and has been shown to achieve Hall mobilities up to an order of magnitude higher compared to multication amorphous semiconductors. In the present work, we compare the electronic structure and electronic transport in a multication amorphous semiconductor, a-IGZO, and a multianion amorphous semiconductor, amorphous zinc oxynitride (a-ZnON) using computational methods. Our results show that, in a-IGZO, the carrier transport path is through the overlap of outer s-orbitals of mixed cations, whereas, in a-ZnON, the transport path is through the overlapping Zn-4s orbitals, which is the only type of metal cation present. We also show that for multicomponent ionic amorphous semiconductors, the electron transport can be explained in terms of the orbital overlap integral, which can be calculated simply from the structural information. The orbital overlap integral has a direct correlation with the carrier effective mass, which is calculated using computationally expensive first-principles density functional theory based methods.
A multi-frequency 3ω method for tracking moving phase boundaries
Authors: Hodges Wyatt , Dames Chris
Published: September 2019

A technique has been developed to track a moving phase front using the electrothermal 3ω method and demonstrated by tracking the location of the phase boundary between air and dielectric oil. A fine wire 3ω sensor (diameter 10 µm, length 30 mm) is suspended in oil and excited at four frequencies simultaneously to gain more thermal information than a single-frequency approach. Measurements of the phase boundary location are compared to camera images to verify their accuracy. For slow front velocities which approximate quasistatic operation, the location of the oil-air front determined from the 3ω approach is found to be accurate to within an average error of under 18 µm (root mean square) for front distances between 12 and 360 µm. Frequency cross talk and other considerations unique to multifrequency measurements are also discussed.
Morphology independent triplet formation in pentalene films: Singlet fission as the triplet formation mechanism
Authors: Wang Long , Wu Yishi , Liu Yanping , Wang Lanfen , Yao Jiannian , Fu Hongbing
Published: September 2019

Singlet fission (SF), a spin-allowed multiexciton generation process, experienced renewed interest in the last decade due to its potential to increase the efficiency of photovoltaic devices. The hurdles now lie in the limited range of SF-capable materials and demanding morphology requirement for an efficient fission process. Although primary fission to yield triplet pair (1TT) can occur independently of film morphology in intramolecular singlet fission (iSF) materials, the separation of the 1TT state has been shown to be highly dependent on the packing motif and morphologies. In this work, we have demonstrated that both iSF and triplet pair separation processes took place irrelevant of molecular order and/or film morphology in a series of pentalene compounds. With the >180% fission efficiency, the suitable triplet energy levels, and the long lifetime of the triplet excitons, these iSF systems can be integrated into practical photovoltaic application.
Analog switching characteristics in TiW/Al2O3/Ta2O5/Ta RRAM devices
Authors: Song Wendong , Wang Weijie , Lee Hock Koon , Li Minghua , Zhuo Victor Yi-Qian , Chen Zhixian , Chui King Jien , Liu Jen-Chieh , Wang I.-Ting , Zhu Yao , Singh Navab
Published: September 2019

In this letter, we report analog switching characteristics in an analog resistive random access memory device based on a TiW/Al2O3/Ta2O5/Ta stack. For this device, both oxides were grown by using an atomic layer deposition system and the oxygen vacancies were found to exist at the interface of these oxides by using angle-resolved X-ray Photoelectron Spectroscopy. The device exhibits analog switching behaviors. Multiple states were achieved by applying 128 consecutive identical pulses of <20 μs duration and stable for at least 104 s. These characteristics show that the TiW/Al2O3/Ta2O5/Ta device is a promising candidate for synaptic applications.
Direct methods for solving the Boltzmann equations: Comparisons with direct simulation Monte Carlo and possibilities
Authors: Aristov V. V. , Voronich I. V. , Zabelok S. A.
Published: September 2019

The possibilities of direct methods for solving the Boltzmann equation in comparison with direct simulation Monte Carlo are discussed. The general features of these different methods are considered, in particular, from the point of view of application of different variants of discretization in phase space. The advantages and disadvantages of both approaches are clarified. Comparative solutions of some simple problems are given. An important issue concerns anomalous heat transfer and validation of the effect by calculations based on these two methods. The solutions of the stationary one-dimensional heat transfer problem between two infinite plates with nonclassical nonequilibrium reflection from the surface are obtained; the anomalous heat transfer with a temperature gradient and a heat flux having the same sign is observed. One-dimensional and two-dimensional (in the square domain) problems with nonequilibrium “membranelike” boundary conditions are solved numerically; the anomalous heat transfer for all the considered cases is demonstrated.
Double hit reconstruction in large area multiplexed detectors
Authors: Radics B. , Janka G. , Cooke D. A. , Procureur S. , Crivelli P.
Published: September 2019

A novel approach is presented to unfold particle hit positions in tracking detectors with multiplexed readout representing an underdetermined system of linear equations. The method does not use any prior information about the hit positions, and the only assumption in the procedure is that single strip charge values on consecutive detector strips follow a smooth distribution. Ambiguities introduced by charge sharing from multiplexing are reduced by using a regularization technique. We have tested this method on a multiplexed 50 × 50 cm2 Micromegas detector with 1037 strips and only 61 readout channels, using cosmic rays, and we have found that single and double clusters of hits can be reconstructed with high efficiency. In addition, simulations show that the algorithm is capable of reconstructing isolated hits in events with larger multiplicity.
Measurement of the size of micrometric voids in dielectric media
Authors: Failache H. , Amy L. , Villalba S. , Lezama A.
Published: September 2019

We have developed a method to measure the characteristic interstice size of transparent porous dielectric media. The method is based upon the observation of the transient decay of alkali atoms contained in the medium pores and excited to a sufficiently long-lived state. We present a simple model describing the dependence of the decay transients on the distance L traveled by the atoms between interstice walls. Fitting of the observed transient data to the model predictions allows the determination of L. The method is tested with two well-characterized micrometric thin cells and used to measure the characteristic interstice size of several porous glass samples.
Highly focused femtosecond laser directed selective boron doping in single SiC nanowire device for n-p conversion
Authors: Huo Jinpeng , Zou Guisheng , Lin Luchan , Wang Kehong , Xing Songling , Zhao Guanlei , Liu Lei , Norman Zhou Y.
Published: September 2019

In this work, site-selective Boron (B) doping in SiC nanowires has been demonstrated by utilizing focused femtosecond (fs) laser irradiation. Raman spectra and electrical performance indicate that the localized element doping in pristine n-type SiC nanowires can convert the segment into p-type. The formation of crystalline defects and vacancies in nanowires under fs laser irradiation, along with the simultaneous dissociation of the dopant molecules, can accelerate the doping process. Single SiC nanowire p-n junction and field-effect transistors with a p-type segment have been fabricated based on the pristine n-type nanowire, showing a modified electrical response as a logic gate to programmed voltage signals. This laser controlled selective doping may provide an alternative for precise element doping in semiconductors at the nanoscale, which can be promising for nanoelectronic unit fabrication.
Efficient thermal conductivity modulation by manipulating interlayer interactions: A comparative study of bilayer graphene and graphite
Authors: Sun Zhehao , Yuan Kunpeng , Chang Zheng , Zhang Xiaoliang , Qin Guangzhao , Tang Dawei
Published: September 2019

The application of graphene in high-performance thermal management has received a lot of attention in recent years, which still needs further exploration and development. Here, based on first-principles calculations, the thermal transport is found to be efficiently modulated by enhancing interlayer interactions in bilayer graphene (BLG), showing a different trend compared to graphite. The results of our work suggest that, by enhancing the interlayer force, the “in-plane” anharmonic phonon transport of BLG while the “out-of-plane” harmonic phonon transport of graphite can be effectively tuned. By manipulating interlayer interactions, a controllable and directed parameter (6% out-of-plane compressing deformation of BLG can achieve more than 25% decrement of in-plane thermal conductivity; 10% out-of-plane compressing deformation of graphite can increase out-of-plane thermal conductivity by more than 5 times) for tuning the thermal conductivity can be achieved. The difference in the effect of the interlayer force on thermal conductivity for low-dimensional and bulk materials emphasizes the significance of the anharmonic phonon transport properties of low-dimensional materials with interlayer interaction and thereby provides an important insight for promoting the future application of bilayer graphene and graphite.
Some characteristics of elastic waves in a piezoelectric semiconductor plate
Authors: Tian Ru , Liu Jinxi , Pan Ernian , Wang Yuesheng , Soh Ai Kah
Published: September 2019

Devices based on piezoelectric semiconductors (PSCs) have recently received particular attention due to their wide bandgap where strain energy band engineering under both static and time-harmonic deformations is the key. In this paper, we investigate and characterize the elastic waves propagating in an anisotropic n-type PSC plate. To achieve our goals, we first introduce the new notations for the extended displacements, stresses, strains, and modulus to arrive at a mathematically elegant extended Stroh formalism. Then, the elastic wave problem is converted into a linear eigenvalue system from which the extended displacements and stresses are expressed in terms of the eigenvalues and eigenvectors. Finally, making use of the boundary conditions on the top and bottom surfaces of the plate, wave dispersion and attenuation are derived analytically. Numerical examples are presented to systematically study the effect of the surface boundary condition, steady-state carrier density, plate thickness, and biasing electric field on the wave speed and attenuation of both shear horizontal and Lamb waves in the transversely isotropic ZnO PSC plate. Some interesting characteristics of the elastic waves observed in this paper could be helpful as theoretical guidance when designing PSC-based devices.
Impact of defects on the electrical properties of p–n diodes formed by implanting Mg and H ions into N-polar GaN
Authors: Iguchi Hiroko , Narita Tetsuo , Kataoka Keita , Kanechika Masakazu , Uedono Akira
Published: September 2019

The relationship between the junction properties and point defects in p–n diodes, formed by implanting magnesium (Mg) and hydrogen (H) ions into a GaN layer, was investigated. Vertical diodes were fabricated by implanting Mg ions with and without H ions into nitrogen-polar n-type GaN substrates, followed by annealing at 1150 °C or 1230 °C without the use of protective layers. Samples annealed at 1150 °C showed Schottky-barrier-diode (SBD)-like properties with an insufficient build-in potential, indicating surface depletion due to poor activation of Mg acceptors. The Mg/H-ion-implanted diode annealed at 1230 °C exhibited an improved rectifying property with a build-in potential around 3 V, close to an ideal p–n junction of GaN, whereas the sample with only implanted Mg-ions exhibited mixed properties of a p–n junction and SBD due to imperfect activation. In addition, leakage currents in the forward bias below 3 V for the Mg/H-ion-implanted diodes can be explained by a recombination current based on the Shockley–Read–Hall model with an estimated recombination lifetime of 3 to 10 ps. To clarify the sources of the difference in the junction properties, positron annihilation spectroscopy was employed. The samples annealed at 1150 °C contained high-density vacancy clusters such as (VGaVN)3, whose concentrations were reduced by the higher temperature annealing. We found that introduced H atoms can enhance the activation of Mg acceptors and/or reduce the defect concentrations. The results indicate the combination of the H ion introduction and higher temperature annealing improves the junction properties.
Conduction mechanisms in ZnO nanowires based Schottky diode grown under an electric field
Authors: Valenzuela-López María Teresa , Herrera-Zaldívar Manuel
Published: September 2019

We present a cathodoluminescence (CL) and electrical study of aligned ZnO nanowires based Schottky diodes synthesized by applying an AC electric field between two Au microcontacts. Our results reveal that the applied electric field aligns the ZnO nanowires between the electrodes and inhibits the formation of ZnO oxygen vacancies (VO). Local CL measurements of ZnO nanowires grown at different zones of the device show that the applied electric field inhibited the formation of oxygen vacancies (VO). Furthermore, CL spectra display an energy shift of the ZnO band edge emission, generated by changes in the relative intensity of two CL bands centered at 3.23 and 3.27 eV that correspond to the donor-acceptor pair and free electrons-acceptor transitions, respectively. We propose the formation of zinc vacancies (VZn) in nanowires that act as acceptor centers in the generation of these two electronic transitions. I-V curves acquired at room temperature reveal the photoresponse of the ZnO nanowires based Schottky diode exposed under UV (365 nm) illumination, exhibiting photocurrent intensities several times higher than that observed under dark conditions for applied bias lower than 1 V. The electrical conduction mechanisms in aligned ZnO nanowires of the device were tunneling and thermionic-emission for applied bias lower than 400 and 700 mV under dark and UV (365 nm) illumination conditions, respectively. For higher bias values, the device showed a conduction mechanism type field-emission.
Directionally controlled open channel microfluidics
Authors: Kunti Golak , Dhar Jayabrata , Bhattacharya Anandaroop , Chakraborty Suman
Published: September 2019

Free-surface microscale flows have been attracting increasing attention from the research community in recent times, as attributable to their diverse fields of applications ranging from fluid mixing and particle manipulation to biochemical processing on a chip. Traditionally, electrically driven processes governing free surface microfluidics are mostly effective in manipulating fluids having characteristically low values of the electrical conductivity (lower than 0.085 S/m). Biological and biochemical processes, on the other hand, typically aim to manipulate fluids having higher electrical conductivities (>0.1 S/m). To circumvent the inherent limitation of traditional electrokinetic processes in manipulating highly conductive fluids in free surface flows, here we experimentally develop a novel on-chip methodology for the same by exploiting the interaction between an alternating electric current and an induced thermal field. We show that the consequent local gradients in physical properties as well as interfacial tension can be tuned to direct the flow toward a specific location on the interface. The present experimental design opens up a new realm of on-chip process control without necessitating the creation of a geometric confinement. We envisage that this will also open up research avenues on open-channel microfluidics, an area that has vastly remained unexplored.
Skyrmion motion induced by voltage-controlled in-plane strain gradients
Authors: Yanes R. , Garcia-Sanchez F. , Luis R. F. , Martinez E. , Raposo V. , Torres L. , Lopez-Diaz L.
Published: September 2019

Micromagnetic simulations are used to investigate the motion of magnetic skyrmions in an in-plane strain gradient. The skyrmion diameter and energy are found to depend on the strain, which leads to a force that moves the skyrmion toward regions with higher strain. An analytical expression for the skyrmion velocity as a function of the strain gradient is derived assuming a rigid profile for the skyrmion, and good agreement with simulations is obtained. Furthermore, electromechanical simulations of a hybrid ferromagnetic/piezoelectric device show that the in-plane strain gradients needed to move skyrmions can be achieved by applying moderate voltages in the piezoelectric substrate, which offers an original way to control skyrmion motion efficiently.
Atomistic investigation of the deformation mechanisms in nanocrystalline Cu with amorphous intergranular films
Authors: Neelav Afzal Hossain , Pal Snehanshu , Deng Chuang
Published: September 2019

Grain boundaries in nanocrystalline (NC) materials are important as they control the microstructural evolution and act as both sinks and sources for dislocation activities. In order to enhance the absorption of dislocations and restrict the crack nucleation and growth, the conventional grain boundaries can be substituted with amorphous intergranular films (AIFs). In the present atomistic study, we investigated the deformation mechanism of bicrystals and NC Cu specimens with AIF under dynamic and static loading conditions with a particular focus on the influence of grain sizes (3 nm–17 nm) and AIF thicknesses (0.5 nm–1.5 nm). We found that the presence of AIF homogenized the interfacial energy irrespective of the grain orientations and decreased its overall value, which posed a strong effect on the strength of the metallic system. In addition, we observed a shift of the deformation mechanism from that dominated by dislocations to interfacial activities due to the presence of AIF as the grain size or AIF thickness changed. Finally, results from high-temperature creep deformation showed that the NC Cu with AIF had excellent thermal stability despite its small grain size.
An aperture coupled microstrip antenna array for high power microwave application
Authors: Xu Liang , Yuan Cheng-Wei , Zhang Qiang , Zhao Xu-hao , Sun Yun-fei , Yu Long-zhou
Published: September 2019

A three-layer aperture coupled microstrip antenna array (ACMA) is designed and fabricated for wideband high-power microwave (HPM) application, which has not been reported in the field of HPM. In this paper, the proposed antenna array overcomes the disadvantage of low power capacity of traditional microstrip antenna arrays. Moreover, based on the H-shaped aperture coupled structure, it enhances the relative bandwidth up to more than 50%. Compared with traditional HPM antennas, it has advantages of being low-profile (less than 0.2λ), wideband, lightweight, and easy to manufacture. The proposed antenna array consists of 60 elements; each element has four aperture coupled patch antennas fed by a four-way microstrip line power divider. In order to realize the modular design, the antenna array is divided into 10 identical modules; benefiting from this design, machining and assembling become easier. Additionally, cold tests and high-power tests are carried out, and the experimental results show that the ACMA achieves a relative bandwidth of 51.2% for voltage standing-wave ratio < 2 from 1.52 to 2.57 GHz. Consistent with simulation results, the measured gain is more than 28.8 dB in the whole bandwidth and it reaches a maximum of 32.1 dB. Finally, the high-power tests show that the power capacity of the proposed ACMA is greater than 140 MW, which proves the feasibility of the design in wideband HPM application.
Scattering of GHz coherent acoustic phonons by silica nanoparticles in water probed with the time-domain Brillouin spectroscopy
Authors: Ponge Marie-Fraise , Liu Liwang , Aristégui Christophe , Audoin Bertrand
Published: September 2019

Coherent acoustic phonons detected by time-domain Brillouin spectroscopy (TDBS) in a liquid medium are strongly attenuated when silica nanoparticles sediment in the liquid. The decrease in the optical signal is due to the strong acoustic scattering by silica nanoparticles whose size matches the wavelength of phonons at the frequency of the Brillouin shift. The control of the acoustic wave-front with nanoparticles thus strongly reduces the undesired Brillouin response of the liquid medium. This is demonstrated with a thin transparent film in water, mimicking a biological sample in a nutritive serum. While strong Brillouin scattering in the particle-free liquid hampers the measurement in the film, we show that TDBS can however be performed in a film of a thickness less than the optical wavelength when scatterers sediment in the liquid.
Intrinsic Rashba coupling due to hydrogen bonding in DNA
Authors: Varela S. , Montañes B. , López F. , Berche B. , Guillot B. , Mujica V. , Medina E.
Published: September 2019

We present an analytical model for the role of hydrogen bonding on the spin-orbit coupling of a model DNA molecule. Here, we analyze in detail the electric fields due to the polarization of the hydrogen bond on the DNA base pairs and derive, within a tight binding analytical band folding approach, an intrinsic Rashba coupling which should dictate the order of the spin active effects in the chiral-induced spin selectivity effect. The coupling found is ten times larger than the intrinsic coupling estimated previously and points out to the predominant role of hydrogen bonding in addition to chirality in the case of biological molecules. We expect similar dominant effects in oligopeptides, where the chiral structure is supported by hydrogen-bonding and bears on orbital carrying transport electrons.
Target search on DNA by interacting molecules: First-passage approach
Authors: Shin Jaeoh , Kolomeisky Anatoly B.
Published: September 2019

Gene regulation is one of the most important fundamental biological processes in living cells. It involves multiple protein molecules that locate specific sites on DNA and assemble gene initiation or gene repression multimolecular complexes. While the protein search dynamics for DNA targets has been intensively investigated, the role of intermolecular interactions during the genetic activation or repression remains not well quantified. Here, we present a simple one-dimensional model of target search for two interacting molecules that can reversibly form a dimer molecular complex, which also participates in the search process. In addition, the proteins have finite residence times on specific target sites, and the gene is activated or repressed when both proteins are simultaneously present at the target. The model is analyzed using first-passage analytical calculations and Monte Carlo computer simulations. It is shown that the search dynamics exhibit a complex behavior depending on the strength of intermolecular interactions and on the target residence times. We also found that the search time shows a nonmonotonic behavior as a function of the dissociation rate for the molecular complex. Physical-chemical arguments to explain these observations are presented. Our theoretical approach highlights the importance of molecular interactions in the complex process of gene activation/repression by multiple transcription factor proteins.
Evaluation of a compulsory reflective group for medical students
Authors: Lack Liza , Yielder Jill , Goodyear-Smith Felicity
Published: September 2019

ABSTRACT INTRODUCTIONThe ability to reflect – reflection – taking time to stop, think and evaluate is an important professional skill to develop. AIMTo evaluate a compulsory reflective group activity to determine whether compulsory participation enabled students to constructively share emotional clinical experiences and develop ethical and professional behaviour. METHODSThis was a case study with mixed methodology. Participants were Years 5 and 6 medical students at the University of Auckland, New Zealand. Data collection included pre- and post-reflective group questionnaires with Year 5 and 6 students, questionnaires with general practice academic facilitators, and audiotapes of the reflection group discussions. RESULTSStudents shared emotional experiences that were organised into three themes: (i) witnessing unprofessional behaviour; (ii) meeting difficult clinical scenarios for the first time; and (iii) the hierarchy of medicine. They reported positive learning experiences relevant to their future practice and valued the opportunity to share their experiences safely. Facilitators thought the groups provided unique educational opportunities that students appreciated. Eighty-two percent of participants would like to repeat the activity during their medical school training. CONCLUSIONSelf-reflection is an essential condition for professionalism. Use of reflective groups can help students become ethical and professional doctors.