bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of polar amino acid incorporation on Fmoc-diphenylalanine-based tetrapeptides
Authors: Ariawan A. Daryl , Sun Biyun , Wojciechowski Jonathan P. , Lin Ian , Du Eric Y. , Goodchild Sophia C. , Cranfield Charles G. , Ittner Lars M. , Thordarson Pall , Martin Adam D.
Published: May 2020

The incorporation of polar amino acids into the Fmoc-FF motif yields tetrapeptide hydrogels whose biocompatibility in the gel state is inversely proportional to their biocompatibility in the solution state.
Design of lanthanide-based metal–organic frameworks with enhanced near-infrared emission
Authors: Nguyen Tu N. , Eliseeva Svetlana V. , Gładysiak Andrzej , Petoud Stéphane , Stylianou Kyriakos C.
Published: May 2020

A strategy based on the use of ligand steric hindrance and metal doping is reported for the design and synthesis of near-infrared (NIR) emitting lanthanide-based metal–organic frameworks (MOFs).
Modulating reactivity and stability of metallic lithiumviaatomic doping
Authors: Lu Ke , Xu Haiping , He Haiying , Gao Siyuan , Li Xun , Zheng Chong , Xu Tao , Cheng Yingwen
Published: May 2020

Doping Li with Ag or Al effectively modulate its inherent chemical activity and enables very stable Li metal batteries.
Carbon-supported Pt5P2nanoparticles used as a high-performance electrocatalyst for the methanol oxidation reaction
Authors: Li Mengmeng , Fang Yan , Zhang Genlei , Cui Peng , Yang Zhenzhen , He Jianbo
Published: May 2020

The Pt5P2/C catalyst achieves a factor of 11.0 and 9.1 enhancement in mass activity (MA) and specific activity (SA) for MOR relative to Pt/C, respectively, while a factor of 9.1 and 7.9 enhancement in MA and SA relative to PtRu/C-JM.
Direct conversion of metal organic frameworks into ultrafine phosphide nanocomposites in multicomponent plasma for wide pH hydrogen evolution
Authors: Guo Yanru , Zhang Chunmei , Wu Yong , Yu Hongen , Zhang Shaojun , Du Aijun , Ostrikov Kostya (Ken) , Zheng Jie , Li Xingguo
Published: May 2020

Multicomponent NH3 plasma enhances the carbon removal effect and activates red phosphorus to PH radicals, resulting in simultaneous MOF decomposition and phosphorization at low temperature.
Structural evolution, electrochemical kinetic properties, and stability of A-site doped perovskite Sr1−xYbxCoO3−δ
Authors: Yang Chunyang , Gan Yun , Lee Myongjin , Ren Chunlei , Brinkman Kyle S. , Green Robert D. , Xue Xingjian
Published: May 2020

Structural evolution occurs upon A-site partial substitution of Sr by Yb in SrCoO3−δ, leading to enhanced performance and stability.
Synergetic enhancement of thermoelectric performance in a Bi0.5Sb1.5Te3/SrTiO3 heterostructure
Authors: Wan Xueying , Liu Zhengmao , Sun Lin , Jiang Peng , Bao Xinhe
Published: May 2020

The thermoelectric output power of the Bi0.5Sb1.5Te3/SrTiO3 heterostructure can be greatly enhanced by the synergetic effect between film and substrate.
Activation of carbon tow electrodes for use in iron aqueous redox systems for electrochemical applications
Authors: Schröder Philipp , Aguiló-Aguayo Noemí , Auer Andrea , Grießer Christoph , Kunze-Liebhäuser Julia , Ma Yibo , Hummel Michael , Obendorf Dagmar , Bechtold Thomas
Published: May 2020

Activation of technical carbon tow opens access to new electrode material and electrode design for all iron redox flow cells.
Influence of thermally induced structural transformations on the magnetic and luminescence properties of tartrate-based chiral lanthanide organic-frameworks
Authors: Huizi-Rayo Uxua , Zabala-Lekuona Andoni , Terenzi Alessio , Cruz Carlos M. , Cuerva Juan M. , Rodríguez-Diéguez Antonio , García Jose Angel , Seco José M. , San Sebastian Eider , Cepeda Javier
Published: May 2020

Chiral 3D microporous lanthanide and tartrate-based MOFs with thermally induced modulation of magnetic/luminescence properties and chiroptical activity.
Achieving high energy density and discharge efficiency in multi-layered PVDF–PMMA nanocomposites composed of 0D BaTiO3 and 1D NaNbO3@SiO2
Authors: Sun Qinzhao , Wang Jiping , Zhang Lixue , Mao Pu , Liu Shujuan , He Liqiang , Kang Fang , Xue Rong
Published: May 2020

The choice of dielectric fillers and structure design play an important role in improving the energy storage properties of polymer-based nanocomposites.
An electroforming-free mechanism for Cu2O solid-electrolyte-based conductive-bridge random access memory (CBRAM)
Authors: Kwon Ki-Hyun , Kim Dong-Won , Kim Hea-Jee , Jin Soo-Min , Woo Dae-Seong , Park Sang-Hong , Park Jea-Gun
Published: May 2020

In a CuxO solid-electrolyte-based CBRAM cell using an Ag top electrode, electroforming-free and electro-reset processes could be achieved at a specificex situannealing temperature of the solid electrolyte.
miR-219a-5p enhances the radiosensitivity of non-small cell lung cancer cells through targeting CD164
Authors: Wei Tao , Cheng Shan , Fu Xiao Na , Feng Lian Jie
Published: May 2020

Lung cancer is one of the leading causes of cancer-associated mortality. Non-small cell lung carcinoma (NSCLC) accounts for 70–85% of the total cases of lung cancer. Radioresistance frequently develops in NSCLC in the middle and later stages of radiotherapy. We investigated the role of miR-219a-5p in radioresistance of NSCLC. miR-219a-5p expression in serum and lung tissue of lung cancer patients was lower than that in control. Compared with radiosensitive (RS) NSCLC patients, miR-219a-5p expression was decreased in serum and lung tissue in radioresistant patients. miR-219a-5p expression level was negatively associated with radioresistance in NSCLC cell lines. Up-regulation of miR-219a-5p increased radiosensitivity in radioresistant NSCLC cells in vitro and in vivo. Down-regulation of miR-219a-5p decreased radiosensitivity in radiosensitive A549 and H358 cells. miR-219a-5p could directly bind in the 3′UTR of CD164 and negatively regulated CD164 expression. CD164 expression was higher in radioresistant NSCLC tissues than RS tissues. Up-regulation of CD164 significantly inhibited miR-219a-5p-induced regulation of RS in radioresistant A549 and H358 cells. Down-regulation of CD164 significantly inhibited the effect of anti-miR-219a-5p on radiosensitive A549 and H358 cells. miR-219a-5p or down-regulation of CD164 could increase apoptosis and γ-H2A histone family member X (γ-H2AX) expression in radioresistant cells in vitro and in vivo. Up-regulation of CD164 could inhibit the effect of miR-219a-5p on apoptosis and γ-H2AX expression. Our results indicated that miR-219a-5p could inhibit CD164, promote DNA damage and apoptosis and enhance irradiation-induced cytotoxicity. The data highlight miR-219a-5p/CD164 pathway in the regulation of radiosensitivity in NSCLC and provide novel targets for potential intervention.
Fine-scale visualizing the hierarchical structure of mouse biliary tree with fluorescence microscopy method
Authors: Chen Yuwei , Bai Lin , Zhou Yongjie , Zhang Xiaoyun , Zhang Jie , Shi Yujun
Published: May 2020

The liver is a vital organ and the hepatic lobule serves as the most basic structural and functional unit which is mainly assembled with parenchymal cells including hepatocytes and biliary epithelial cells. The continuous tubular arrangement of biliary cells which constitutes the biliary tracts is critical for liver function, however, the biliary tracts are often disrupted in many liver diseases such as cirrhosis and some congenital disorders. Visualization of the biliary tracts in fine-scale and three-dimension will help to understanding the structure basis of these liver diseases. In the present study, we established several biliary tract injury mouse models by diet feeding, surgery or genetic modification. The cytoplasm and nuclei of the parenchymal cells were marked by active uptake of fluorescent dyes Rhodamine B (red) and Hoechst (blue), respectively. After the removal of liver en bloc, the biliary tracts were retrogradely perfused with green fluorescent dye, fluorescein isothiocyanate (FITC). The liver was then observed under confocal microscopy. The fine-scale and three-dimensional (3D) structure of the whole biliary tree, particularly the network of the end-terminal bile canaliculi and neighboring hepatocytes were clearly visualized. The biliary tracts displayed clear distinct characteristics in normal liver and diseased liver models. Taken together, we have developed a simple and repeatable imaging method to visualize the fine-scale and hierarchical architecture of the biliary tracts spreading in the mouse liver.
Horizonterweiterung zwischen Arktis, Tropen und Antarktis
Authors: Staak Ludwig , Ottomann Christian
Published: May 2020

Forschungsschiffe operieren häufig in sehr abgelegenen Gegenden. Da bei Erkrankungen Hilfe gar nicht oder nur schwer erreichbar ist, ergibt sich hier ein Betätigungsfeld für Ärzte, die sich auf diese spezielle Situation einlassen mögen. Im Folgenden werden das Forschungsschif F/S „Maria S. Merian“ mit seinen Aufgaben, deren Bordhospital und Bordarzt vorgestellt.
Heute ist heute
Authors: Gritsch Simone
Published: May 2020

Ich schreibe diesen Beitrag Ende März 2020 und vermute, dass sich unser Leben erneut auf links gedreht hat, wenn Sie das Heft in den Händen halten.
Ein Evidenz-Update – Handparaffinbad
Authors: Veit Katrin , Zumhasch Rainer
Published: May 2020

Schon lange sind die positiven Effekte eines Paraffinbads bekannt, beispielsweise für Patienten mit Arthrose. Rainer Zumhasch und Katrin Veit haben die aktuelle Studienlage zur Effektivität des Paraffinbads bei verschiedenen Erkrankungen gescannt und die Ergebnisse zusammengestellt.
In Vitro and In Vivo Metabolic Activation of Obacunone, A Bioactive and Potentially Hepatotoxic Constituent of Dictamni Cortex
Authors: Lang Xiuzhuang , Zhang Xiangmei , Wang Daoquan , Zhou Weiqing
Published: May 2020

Obacunone is one of the major bioactive constituents from Dictamni cortex, a traditional Chinese medicine widely used in China. Oral administration of obacunone or Dictamni cortex extract has been shown to cause liver injury in rats. Given that obacunone contains a furan ring, which is a structural alert, metabolic activation might be responsible for obacunone-induced liver injury. In this study, bioactivation pathways of obacunone in rat and human liver microsomes were investigated. Obacunone was first metabolized into cis-butene-1,4-dial, and then cis-butene-1,4-dial was captured by glutathione, N-acetyl-cysteine, and N-acetyl-lysine in the microsomal incubation system. A total of 13 adducts derived from the reaction of cis-butene-1,4-dial with glutathione and/or N-acetyl-lysine were detected and structurally identified by liquid chromatography coupled to high-resolution tandem mass spectrometry. The major metabolite (M7) was identified to be the cyclic mono-glutathione conjugate of cis-butene-1,4-dial, which was detected in bile and urine of obacunone-treated rats. M9 and M10, obacunone-derived glutathione-cis-butene-1,4-dial-NAL conjugates, were detected in the microsomal incubations of obacunone fortified with glutathione and N-acetyl-lysine as trapping agents. M3 and M4, pyrroline-2-one derivatives, were also detected in microsomal incubations. Further phenotyping studies indicated that ketoconazole showed a strong inhibitory effect on the production of cis-butene-1,4-dial in a concentration-dependent manner. CYP3A4 was demonstrated to be the primary enzyme responsible for the bioactivation of obacunone by using individual recombinant human CYP450 enzymes. The current study provides an overview of CYP450-dominated bioactivation of obacunone and contributes to the understanding of the role of bioactivation in obacunone-induced liver injury.
Sektorenübergreifende Versorgung in der Pädiatrischen
Onkologie: Qualitätssicherung durch neue Vergütungsmodelle
für nicht-vollstationäre Leistungen
Authors: Reinke Evelyn , Jürgens Heribert , Haier Jörg , Froehlich Birgit , Kontny Udo , Rossig Claudia
Published: May 2020

Hintergrund Die pädiatrisch-onkologische Versorgungsstruktur
nimmt in Deutschland eine Sonderrolle ein. An Krebs erkrankte Kinder und
Jugendliche werden bundesweit einheitlich in Therapiestudien und Registern
sektorenübergreifend an Zentren behandelt, die eine
interdisziplinäre und multiprofessionelle Versorgung sicherstellen
können. Für die Abrechnung der nicht-vollstationären
Leistungen verwenden die Zentren heterogene Abrechnungsmodalitäten, die
den erforderlichen Versorgungsaufwand monetär überwiegend nicht
decken.

Methode Es wurde deutschlandweit eine Umfrage aller Zentren der
Gesellschaft für Pädiatrische Hämatologie und Onkologie
(GPOH) durchgeführt. In der Umfrage wurde standardisiert abgefragt,
über welche Versorgungsarten der nicht-vollstationäre Bereich in
der Kinderonkologie finanziert wird und ob eine Kostendeckung erreicht werden
kann.

Ergebnisse Von 58 kinderonkologischen Zentren beteiligten sich insgesamt
18 (33%) an der Umfrage, darunter 8 (44%)
Universitätsklinika. Die Inanspruchnahme verfügbarer
Abrechnungsarten erwies sich als sehr heterogen. Im Mittel werden
3,33±1,49 Abrechnungsarten pro Zentrum angewandt. 17 der 18
teilnehmenden Zentren gaben an, mit den Erlösen die Kosten für
die nicht-vollstationäre Versorgung nicht decken zu können.

Diskussion und Schlussfolgerung Kinderonkologische Zentren in Deutschland
können eine kostendeckende Versorgung im nicht-vollstationären
Setting nicht erreichen. Für die nicht-vollstationäre Versorgung
an Krebs erkrankter Kinder und Jugendlicher wird eine bundeseinheitliche und
leistungsgerechte Versorgungsform dringend benötigt. Drei verschiedene
Modelle, die einen adäquaten Handlungsrahmen bieten, wurden erarbeitet
und vorgestellt.
Successful Endoscopic Ultrasound Guided Drainage of Large Lesser Sac Abscess Cavity Postgastric Ulcer Sealed-Off Perforation: Novel Approach
Authors: Bhatt Keyur , Mangukiya Dhaval , Desai Pankaj , Parekh Krishna
Published: May 2020

Endoscopic ultrasonography (EUS) guided drainage is a beneficial and safe therapeutic tool that is used for the treatment of pancreatic mass and pseudocysts. Currently, the application of EUS-guided drainage is increasing for the treatment of different complications such as intraperitoneal abscess drainage following perforated peptic ulcer (PPU) or pararectal abscess. The intraperitoneal abscess with PPU is traditionally treated with surgical treatment. Herein, we report a lesser invasive drainage technique in the form of EUS-guided drainage for the treatment of intraperitoneal abscess.
PREVALENCE OF OBESITY AMONG HIGH SCHOOL CHILDREN IN DAKSHINA KANNADA AND UDUPI DISTRICTS
Authors: M. Keerthan Kumar , K. Prashanth , Baby Kavya Elizabeth , Rao Kavya Rashmi , B. Kumarkrishna , Hegde Krishnamurthy , Kumar Mrinal , Shetty Manish , N. Navya , P. Kavya C. , G. Sandeep Kumar , R. Rahul
Published: May 2020

Objective: The aim of this project is to find out the prevalence of overweight and obesity in the high school children in selected schools of Mangalore and Manipal and also to study the association of obesity with different factors like Age, Sex, Physical activity etc.

Methods: Cross sectional Study which included 500 participants from 10 selected schools in Udupi and D.K districts. 50 students were rd included from each school on the basis of 1 in 5 choosing every 3rd student. In schools with lesser attendance all were included. Following which they were explained the details about the study. Then their height and weight were recorded using standard measurements and the data was collected using the questionnaire.

Results: The overall prevalence of obesity and overweight was found to be 2.6% and 3.0% respectively. Prevalence was found to be higher in males, those studying in private schools, staying in nuclear family, consuming fried foods-aerated drinks regularly and in those who do not exercise regularly.

Conclusions: Childhood obesity is a major public health problem globally because of changes in lifestyle.
MANAGEMENT OF ACUTE CORNEAL HYDROPS SECONDARY TO KERATOCONUS BY DESCEMETOPEXY USING INTRACAMERAL PERFLUOROPROPANE (C3F8 ) – A CASE REPORT
Authors: Pai Vijay , Shetty Jayaram , Amin Hrishikesh , Bhat S. , Lakshmi Divya
Published: May 2020

Keratoconus is a clinical term used to describe bilateral non-inflammatory corneal ectasia in its axial part due to which cornea assumes a conical shape1. The onset of keratoconus is generally at the age of puberty, and progresses over a period of 10-20 years2,3. The treatment of Keratoconus is rarely an emergency, with the exception of corneal hydrops resulting from rupture of the Descemet's membrane. This may be the common mode of presentation in patients with associated developmental delay, probably related to habitual ocular massage4,5.
INTRA-ARTICULAR SYNOVIAL HEMANGIOMA OF KNEE OVERLYING POSTERIOR CRUCIATE LIGAMENT - A CASE REPORT
Authors: S. Dileep K. , Kanakaraddi Sandeep V. , S. Vidyasagar J.V. , S. Radha , Aroor Akshatha Rao
Published: May 2020

Hemangioma of synovium is a rare benign tumor that can arise from any surface lined by synovium. Intra-articular synovial hemangioma is most common in the knee joint. The diagnosis is difficult as the signs and symptoms are nonspecific. We hereby report a hitherto unreported case of synovial hemangioma of knee overlying posterior cruciate ligament, its MRI findings and discuss the appropriate management
A COMBINATION OF PIGMENTED VILLONODULAR SYNOVITIS AND SYNOVIAL CHONDROMATOSIS PRESENTING AS A LARGE LOOSE BODY IN KNEE
Authors: Shetty Siddharth , Shetty Vikram , Shetty B. J.P. , Bhat Shubha P.
Published: May 2020

Intra-articular calcific lesions of knee usually manifest as loose bodies with symptoms of recurring episodes of locking and restriction of movement. These loose bodies are a consequence of trauma or degeneration of structures in the joint and occasionally may be of inflammatory or neoplastic condition of the synovium.

Here we present our case as a rare form of presentation where in our patient had a large loose body in the knee with chronic pain and swelling and restriction of the movements of knee. Arthrotomy, loose body excision and total synovectomy of the knee confirmed coexistence of a dual lesion of synovial chondromatosis of the Hoffa's fat pad with diffuse pigmented villonodular synovitis of the knee joint. The patient made an uneventful recovery and full range of knee movement was restored by end 3 months. These benign conditions have inherent risk of recurrence, and in our case, till the last follow up at 14 months after surgery, he has remained asymptomatic with no clinico radiological evidence of any recurrence.
A Chestnut–A Difficult Challenge for an Endoscopist
Authors: Zykutė Dalia , Zykus Romanas
Published: May 2020

True foreign bodies are a frequent problem in mentally disabled adults and since ingestion is usually intentional, retrieval can be difficult due to unusual, previously in practice not encountered objects. This case illustrates the laborious effort of removing an esophageal foreign body (FB), a chestnut, in a mentally disabled adult.
COMPARATIVE EVALUATION OF DIABETOGENIC AND MUTAGENIC POTENTIAL OF ARTIFICIAL SWEETENERS - ASPARTAME, ACESULFAME-K AND SUCRALOSE
Authors: S. Shastry C. , K. Yatheesh C. , J. Aswathanarayana B.
Published: May 2020

Objectives: Artificial sweeteners provide the sweetness of sugar without calories. Since from discovery, safety of artificial sweeteners has been controversial as they directly or indirectly link to induce carcinogenic and genotoxic risks. Hence the present study was undertaken to compare the diabetogenic and mutagenic potential of most widely using artificial sweeteners; aspartame, acesulfame-K, and sucralose.

Methods: Diabetic potential is assessed by ascending repeated dose study in which acceptable daily intake (ADI) dose of artificial sweeteners after converting human dose to animal dose using a standard reference table and administered up to 13 weeks with 3 different phases in an ascending manner on experimental rats. Mutagenic potential was accessed by Ames test with and without metabolic activation using Salmonella typhimurium strains TA 97 and TA1535.

Results: At ADI doses between 0-3 weeks, no significant changes but after 13 weeks significant increase was observed in the levels of fasting blood glucose, glycated haemoglobin, total cholesterol, triglyceride, LDL and VLDL in all artificial sweetener groups. Sucralose showed comparatively less increase which was supported by histology reports. In Ames mutagenic assay aspartame, acesulfame-K and sucralose gave negative results.

Conclusion: Aspartame, acesulfame-K and sucralose were found to exhibit diabetogenic effect at higher dose levels but they were safer to use at ADI doses and non mutagenic compounds. Comparatively sucralose is safer than aspartame and acesulfame-K. Hence these artificial sweeteners should be used with caution and over usage is not appreciated.
Single-Balloon Enteroscopy—Guided ERCP in Surgically Altered Anatomy Is Safe and Highly Effective: Results from a Prospective Study
Authors: Pal Partha , Kulkarni Sujay Ashok , Chaudhari Hrushikesh , Ramchandani Mohan , Reddy P. Manohar , Shrimal Pankaj Kumar , Reddy D. Nageshwar , Tandan Manu
Published: May 2020

Objectives Single-balloon enteroscopy (SBE)—assisted endoscopic retrograde cholangiopancreatography (ERCP) has been shown to be cost effective and less technically demanding than other modes of device-assisted enteroscopy. We aimed to evaluate the safety and efficacy of SBE-ERCP in surgically altered anatomy.

Methods This was a prospective cohort study in a high-volume tertiary care gastroenterology center. Patients with surgically altered anatomy requiring pancreaticobiliary interventions, who failed ERCP with a colonoscope/duodenoscope, underwent SBE-ERCP. Diagnostic and therapeutic success, procedure time, and adverse events were evaluated prospectively with short-term follow-up.

Results Twenty-eight patients with surgically altered anatomy (19 males, aged 15–66 years) underwent total 40 SBE-ERCP (23 Roux-en-Y, 17 Billroth II anatomy) procedures. The ERCP diagnosis were hepaticojejunostomy (HJ) stricture (N = 10), HJ stricture and stone (N = 7), common bile duct (CBD) stricture (N = 6), CBD stone (N = 1), pancreaticojejunostomy (PJ) stricture (N = 1), and pancreatic duct (PD) stricture (N = 1). Diagnostic success was achieved in 91.3% (21/23) patients with Roux-en-Y anatomy and 100% (17/17) with Billroth II anatomy. Therapeutic success was achieved in 86.95% (20/23) and 94.1% (16/17) patients with Roux-en-Y and Billroth II anatomy, respectively. In patients with intact papilla (N = 8), diagnostic and therapeutic success were achieved in 100% (8/8) and 75% (6/8) cases, respectively. The mean procedure time for Roux-en-Y and Billroth II anatomy were 64.95 minutes (range 30–110 min) and 38.31 minutes (range 25–60 min), respectively. Immediate complications occurred in 7.5% (3/40) procedures (2 requiring laparotomy, 1 treated endoscopically) in the form of perforation. Among delayed complications, 5 patients had cholangitis and 1 had recurrent cholestasis, which were successfully treated with stent exchange. No other complications occurred over median follow-up of 110 days (30–390 d).

Conclusion SBE-ERCP in surgically altered anatomy requiring pancreatic–biliary intervention appears safe and highly effective with current long ERCP accessories. Further improvement in SBE-ERCP technique and accessories has the potential to make it a promising avenue in surgically altered anatomy.
Finite amplitude torsional oscillations of shape-morphing plates immersed in viscous fluids
Authors: Ahsan Syed N. , Aureli Matteo
Published: May 2020

In this paper, we study torsional oscillations of a cross section of a thin plate submerged in a quiescent, Newtonian, incompressible, and viscous fluid. The plate is subjected to a prescribed shape-morphing deformation in phase with the rigid oscillation. The problem is completely described by three nondimensional parameters indicating oscillation frequency and amplitude and intensity of the shape-morphing deformation. We conduct a parametric study to investigate the possibility of controlling hydrodynamic moments and power dissipation through an active time-varying shape-morphing strategy. The problem is studied in both the linear and nonlinear flow regimes, by employing the boundary element method and direct numerical simulations via computational fluid dynamics methods, respectively. Investigation of flow physics demonstrates that, similarly to what is observed for the case of flexural oscillations, the shape-morphing strategy is effective in modulating vortex shedding in torsional oscillations. The results show that hydrodynamic power dissipation can be minimized and hydrodynamic moments can be controlled through an optimal imposed shape-morphing deformation. Findings from this study are directly applicable to torsional oscillation-based underwater energy harvesting or sensing and actuation systems, where control of hydrodynamic moments and reduction of hydrodynamic power losses are necessary for optimal device operation.
Electrical and photo-electrical properties of spin-coated nanocrystalline PbS thin films evaluated using thermoelectric effect
Authors: Vankhade Dhaval , Chaudhuri Tapas K.
Published: May 2020

Nanocrystalline (NC) PbS films have the potential to be used as tunable photodetectors and solar cells, but their electrical properties are not yet understood. The electrical and photo-electrical properties of NC PbS thin films deposited by spin-coating have been investigated. The films are p-type and photoconducting. Electrical conductivity (σ), thermoelectric power (αth), hole concentration (p), and mobility (μ) of the films in dark and under illumination were measured in the temperature range of 77–300 K. These parameters behaved differently in the low temperature region (LTR) of 77–150 K and the high temperature region (HTR) of 250–300 K. In LTR, dark p was constant (∼1014 cm−3) while thermally activated in HTR. In LTR, dark μ varied as T1.5 due to impurity scattering, while in HTR, μ varied as T−(4.2–9.2) due to lattice scattering. Under light, p was ∼1018 cm−3 in LTR while thermal quenching occurred in HTR suggesting the existence of electron traps below the conduction band, which act as sensitization centers. The quenching energy was 130–90 meV, which varied with film thickness. The μ of illuminated PbS films decreased with temperature as T−n due to lattice scattering. The NC PbS films showed high photoconductivity in LTR with a light to dark conductivity ratio of 103. Photoconductivity is explained on the basis of trapping of minority carriers by sensitization centers.
Economical Laue x-ray diffraction using photographic film and orientation of single crystals
Authors: Christian A. B. , Neumeier J. J. , Cone R. L.
Published: May 2020

Many Laue x-ray diffraction systems using the Polaroid XR-7 Land Diffraction Cassette camera became inactive after production of the required high sensitivity Polaroid T-57 instant film ceased. This Tutorial reports on a low-cost solution using the readily available replacement film with push processing to increase the effective film speed. The use of this film in the polaroid camera is described along with film development and digitization. The orientation of single crystals with the obtained data and free software is explained. A simple method to prepare single crystals with surfaces perpendicular to a desired crystallographic orientation is described. The content of this Tutorial may prove beneficial for educational and research laboratories.
Pressure-induced first order phase transition in bulk GeSe
Authors: Kagdada Hardik L. , Jha Prafulla K. , Śpiewak Piotr , Kurzydłowski Krzysztof J. , Singh Dheeraj K.
Published: May 2020

The phase transition mechanism in germanium selenide (GeSe) from the rhombohedral to face-centered cubic (FCC) phase is extensively analysed using density functional theory (DFT). The energy profile of GeSe reveals that the rhombohedral structure lies at the minimum energy, and the enthalpy differences predict its transition to the FCC phase at 7.3 GPa. Furthermore, we confirm the phase transition by calculating the phonon dispersion curves at various pressures. The rhombohedral phase of GeSe is dynamically stable at 0 GPa, whereas the FCC phase shows stability at 7.3 GPa. The rhombohedral to FCC phase transition is scrutinized by the degeneracy and splitting of the phonon modes along with the components of Born effective charge and dielectric constant. Investigation of the lattice transport properties of GeSe in both phases shows that FCC possesses high thermal conductivity (8.06 W/m K) as compared to the rhombohedral phase (4.88 W/m K) due to the three phonon emission process for scattering channels. The electronic band structure of the FCC GeSe under pressure shows its topological nature, and similar behavior was observed in the rhombohedral phase at 7.3 GPa. The rhombohedral phase of GeSe manifests better thermoelectric performance at 0 GPa with the thermoelectric figure of merit of 0.82 at 300 k much higher than its FCC phase at 7.3 GPa, suggesting its application in thermoelectric energy conversion.
Double perovskite Ba2BiTaO6 as a promising p-type transparent conductive oxide: A first-principles defect study
Authors: Yin Yuan , Wu Yelong , Chen Guangde , Yin Wan-Jian
Published: May 2020

The realization of p-type transparent conductive oxides (TCOs) is a long-standing difficulty because of their generally large hole effective mass and low doping limit ascribed to the strong electronegativity of oxygen. By introducing a Bi atom with a lone-pair s orbital on the B site, double perovskite Ba2BiTaO6 could exhibit a dispersive upper valence band and a small hole effective mass due to the strong sp antibonding coupling. In contrast to n-type TCOs, i.e., ZnO and In2O3, first-principles studies on the intrinsic defects of Ba2BiTaO6 show that it is able to exhibit a good p-type property or stay intrinsic instead of being n-type by tuning the chemical potentials and its dominated defects (VBa, VBi, BaBi, and BiTa) are shallow acceptors, indicating that Ba2BiTaO6 is able to be a promising p-type TCO. This work shows that perovskites could be a class of potential p-type TCOs by introducing strong sp coupling with lone-pair-s-orbital elements.
Essential chaotic dynamics of chatter in turning processes
Authors: Beri B. , Stepan G.
Published: May 2020

Large-amplitude oscillations of turning operations are investigated, which can be modelled by a one degree-of-freedom damped oscillator subjected to the regenerative effect that introduces a relevant time delay in the system. In the case of large oscillations, when the cutting tool loses contact with the surface of the workpiece, the time delay is switched off, leading to a non-smooth delay differential equation. To explore the geometric structure of the global dynamics of the system, the mathematical model is approximated by means of the essential part of the spectrum in the region where the stationary cutting process may lose its stability. The trajectories embedded in the infinite-dimensional phase space are interpreted in a three-dimensional subspace and then analyzed by means of a discrete Lorenz-map. The bifurcation diagrams of the non-smooth system include chaotic windows, which are presented by numerical and semi-analytical tools and compared to the existing results in the literature.
Use of hydrodynamic theory to estimate electrical current redistribution in metals
Authors: Yu E. P. , Awe T. J. , Cochrane K. R. , Yates K. C. , Hutchinson T. M. , Peterson K. J. , Bauer B. S.
Published: May 2020

Using the analogy between hydrodynamic and electrical current flow, we study how electrical current density j redistributes and amplifies due to two commonly encountered inhomogeneities in metals. First, we consider flow around a spherical resistive inclusion and find significant j amplification, independent of inclusion size. Hence, even μm-scale inclusions can affect performance in applications by creating localized regions of enhanced Joule heating. Next, we investigate j redistribution due to surface roughness, idealized as a sinusoidal perturbation with amplitude A and wavelength λ. Theory predicts that j amplification is determined by the ratio A/λ, so that even “smooth” surface finishes (i.e., small A) can generate significant amplification, if λ is correspondingly small. We compare theory with magnetohydrodynamic simulation to illustrate both the utility and limitations of the steady-state theory.
Compressible flow in a Noble–Abel stiffened gas fluid
Authors: Radulescu M. I.
Published: May 2020

While the compressible flow theory has relied on the perfect gas model as its workhorse for the past century, compressible dynamics in dense gases, solids, and liquids have relied on many complex equations of state, yielding limited insight into the hydrodynamic aspect of the problems solved. Recently, Le Métayer and Saurel studied a simple yet promising equation of state owing to its ability to model both the thermal and compressibility aspects of the medium. It is a hybrid of the Noble–Abel equation of state and the stiffened gas model, labeled the Noble–Able Stiffened Gas (NASG) equation of state. In the present work, we derive the closed form analytical framework for modeling compressible flow in a medium approximated by the NASG equations of state. We derive the expressions for the isentrope, sound speed, isentropic exponent, Riemann variables in the characteristic description, and jump conditions for shocks, deflagrations, and detonations. We also illustrate the usefulness by addressing the Riemann problem. The closed form solutions generalize in a transparent way the well-established models for a perfect gas, highlighting the role of the medium’s compressibility.
Realizing isotropic negative thermal expansion covering room temperature by breaking the superstructure of ZrV2O7
Authors: Wei Wei , Gao Qilong , Guo Juan , Chao Mingju , He Lunhua , Chen Jun , Liang Erjun
Published: May 2020

ZrV2O7 is a well-known isotropic negative thermal expansion (NTE) material. However, the NTE property of ZrV2O7 can only be observed in high temperatures above 375 K. In this paper, we report a facile method to break the superstructure of ZrV2O7 for realizing the NTE property of ZrV2O7 to room temperature by partial substitution of Mo for V atoms. The detailed structure information and the phase transition process are revealed by high-resolution synchrotron x-ray diffraction, neutron powder diffraction, and high pressure Raman spectral analyses. It is found that the incorporation of Mo prompts the V-O2-V/Mo angles to expand from 160° to 180°, which enables the NTE property at room temperature. Different from most open framework structures where NTE is dominated by low energy phonons, here several high energy phonon modes are found to have negative Grüneisen parameters and contribute to the negative thermal expansion.
Artificial carbon cilium using induced charge electro-osmosis
Authors: Sugioka Hideyuki , Ishikawa Masato
Published: May 2020

Artificial cilia are promising as a next generation microfluidic device. In this study, we experimentally report that fibrous carbon wires produced by the self-organization process show cilium motions due to induced charge electro-osmosis (ICEO) under AC electric fields in water. In particular, we experimentally demonstrate that the carbon ICEO cilium with a branching wire structure shows asymmetric beating motion. We believe that our findings will contribute to the research of artificial cilia having asymmetrical motions, which would provide net propulsion in a low Reynolds number regime.
Impact of metal silicide nanocrystals on the resistance ratio in resistive switching of epitaxial Fe3O4 films on Si substrates
Authors: Ishibe Takafumi , Uematsu Yuto , Naruse Nobuyasu , Mera Yutaka , Nakamura Yoshiaki
Published: May 2020

Fe3O4 films on Si substrates have been intensively studied for the realization of resistance random access memory composed of only ubiquitous elements. The biggest issue for the application of Fe3O4 film/Si in small-scaled devices is the low Off/On resistance ratio. For the enhancement of the Off/On resistance ratio, we propose epitaxial Fe3O4 films including hemispherical small metal α-FeSi2 nanocrystals on Si substrates, where an electric field is concentrated at the interface between Fe3O4/α-FeSi2. The concentrated electric field largely promotes the movement of oxygen ions, contributing to resistive switching. As a result, the Fe3O4 films including hemispherical small α-FeSi2 nanocrystals exhibit the largest Off/On resistance ratio (∼200) in Fe3O4-based nanomaterials. Finite element method simulations proved that the introduction of metal nanocrystals into films caused the enhancement of electric field intensity near the interface between nanocrystals and films. This significant enhancement method will open an avenue for realizing high-performance ubiquitous-element resistive switching materials in the next-generation information society.
Influence of casting substrate on bulk morphology and vanadium ion transport in ionomer nanocomposites
Authors: Domhoff Allison , Davis Eric M.
Published: May 2020

Perfluorosulfonic acid (PFSA) ionomer nanocomposites are a promising solution to address the poor ion selectivity of current membranes utilized in vanadium redox flow batteries. Herein, we investigate the impact of a casting substrate on the nanostructure and vanadium ion transport in bulk ionomer and ionomer nanocomposite membranes (i.e., films with thicknesses of ∼100 μm). Specifically, solution-cast ionomer nanocomposite membranes, containing either unfunctionalized (hydroxyl groups), amine-functionalized, or sulfonic acid-functionalized silica nanoparticles (SiNPs), were fabricated by casting on either a polished quartz or polytetrafluoroethylene (PTFE) substrates. Surprisingly, the choice of the casting substrate was seen to affect the bulk morphology of the PFSA ionomers, resulting in substrate-specific vanadium ion transport, where suppressed ion transport was observed for membranes cast on the polished quartz, when compared to their PTFE-cast counterparts. Additionally, the chemical composition of the substrate-adjacent surface was a function of both the substrate and the surface functionality of the SiNPs. Moreover, it was observed that both the chemical composition of the membrane surface and the substrate-induced changes to the bulk ionomer morphology governed vanadyl ion transport through the PFSA ionomers. Results from this work have direct implications for the design of next-generation ionomer nanocomposites, as the casting substrate used to fabricate these materials, and the orientation of these membranes inside the operating flow battery, can significantly influence transport of vanadium ions.
Automatic triangular and triangular-prism mesh generation for overland and subsurface water flow simulations
Authors: Sun Lu , Zhao Guoqun , Yeh Gour-Tsyh
Published: May 2020

In this paper, an automatic mesh generator is developed to simulate density-dependent water flow and transport problems in watershed systems. The two-dimensional (2D) triangular mesh is generated by global Delaunay triangulation, and the three-dimensional (3D) triangular-prism mesh is generated by vertical stretch. The implementation procedures of mesh generation are adjusted according to the interaction options of one-dimensional (1D) river, 2D overland, and 3D subsurface flows. An improved boundary point generation algorithm is proposed to maintain appropriate correspondence of points and edges according to the discrete patterns of river reaches and dead ends. Overlapped nodes are generated on zero-width river reaches and zero-width junctions without storage to construct the numerical models for 2D overland simulations. An additional triangular mesh generation method is proposed to create additional triangles for filling the empty water zones of finite-width river reaches, junctions with storage, finite-width ponds, lakes, and dead ends. The boundary loops bounding each water area are identified correctly, and the additional grids are created compatibly, aiming at the finite-depth and zero-depth patterns of storage zones. The computation equations of relevant parameters used for 3D stretch from triangles to triangular-prisms are built, and the 1D/2D/3D correspondence on river reaches, junctions, ponds, lakes, dead ends, and control structures is established. Finally, practical examples for discretizing real-world water areas are provided to demonstrate the robustness and effectiveness of our developed mesh generator by using the skewness as the mesh quality metric.
First-principles study of helium behavior in nickel with noble gas incorporation
Authors: Liao Liang-Xiang , Zhang Xun , Ren Cui-Lan , Zhang Zheng-De , Huang He-Fei , Ma Guo-Hong , Huai Ping
Published: May 2020

The behavior of helium in nickel with noble gas atom (helium, neon, argon, krypton, and xenon) incorporations is systematically studied by using the first-principles method. The formation energies of noble gas atoms in nickel increase with atomic size increase from helium to xenon. All noble gas atoms considered in this work energetically prefer to stay at the substitutional sites when compared to the interstitial ones. The variations in formation energies among noble gas atoms can be mainly attributed to the steric effects caused by their incorporation. The chemical binding between nickel and noble gas atoms are further identified by their projected density of states. The substitutional noble gas shows a trapping effect on interstitial helium, and their binding energies also exhibit an approximately linear relation with their size. In addition, the effect of noble gas incorporation on helium clustering in nickel is studied. It shows that noble gas atoms attract small helium clusters and further repel the relatively larger ones. The results help to understand the influence of noble gas atoms on the fundamental helium behavior such as helium stability, trapping, and clustering in nickel and are also technologically important for further study on helium bubble nucleation under similar irradiation conditions.
A Paul trap with sectored ring electrodes for experiments with two-dimensional ion crystals
Authors: Ivory M. K. , Kato A. , Hasanzadeh A. , Blinov B. B.
Published: May 2020

We have developed a trapped ion system for producing two-dimensional (2D) ion crystals for applications in scalable quantum computing, quantum simulations, and 2D crystal phase transition and defect studies. The trap is a modification of a Paul trap with its ring electrode flattened and split into eight identical sectors and its two endcap electrodes shaped as truncated hollow cones for laser and imaging optics access. All ten trap electrodes can be independently DC-biased to create various aspect ratio trap geometries. We trap and Doppler cool 2D crystals of up to 30 Ba+ ions and demonstrate the tunability of the trapping potential both in the plane of the crystal and in the transverse direction.
High mobility conducting channel at semi-insulating GaAs–metal oxide interfaces
Authors: Kopnov G. , Gerber A.
Published: May 2020

The absence of an efficient technology of GaAs passivation limits the use of III–V semiconductors in modern electronics. The effect reported here can possibly lead to a solution to this long standing problem. We found that an electrically conducting interfacial channel is formed when insulating metal oxide dielectrics are deposited on untreated semi-insulating GaAs wafers by reactive RF sputtering in argon/oxygen plasma. The conducting channel is n-type with a surface charge density of 107–1010 cm−2 and Hall mobility as high as 6000 cm2/V s, depending on the RF plasma excitation power and the oxygen content during deposition. The conducting channel is formed by depositing any of the tested metal oxide dielectrics: MgO, SiO2, Al2O3, and HfO2.
GaAs growth rates of 528 μm/h using dynamic-hydride vapor phase epitaxy with a nitrogen carrier gas
Authors: McClure Elisabeth L. , Schulte Kevin L. , Simon John , Metaferia Wondwosen , Ptak Aaron J.
Published: May 2020

We demonstrate record GaAs growth rates approaching 530 μm/h using nitrogen carrier gas and 400 μm/h using hydrogen carrier gas in a dynamic-hydride vapor phase epitaxy reactor. We measured root mean square surface roughness below 1 nm using a 1 μm × 1 μm atomic force microscopy scan for GaAs growth rates up to 483 μm/h using a nitrogen carrier gas and 400 μm/h using a hydrogen carrier gas. We performed computational fluid dynamics modeling to study the effect of the carrier gas choice on the thermal profile within the reactor and how that influences the degree of AsH3 decomposition. The modeling suggests that the lower thermal conductivity of the nitrogen carrier gas minimizes the amount of AsH3 that thermally decomposes before reaching the wafer surface and the heavier atomic mass decreases the likelihood that AsH3 will reach the heated reactor walls, leading to a growth rate enhancement relative to the hydrogen carrier case in a hydride-enhanced growth regime.
Shear-induced viscosity stratified flow past a pair of heated side-by-side square cylinders in a confined domain
Authors: Sanyal Aniruddha , Dhiman Amit
Published: May 2020

In this article, investigations have been carried out to decipher the effect of thermal buoyancy in a viscosity stratified flow field for a shear-thinning fluid flowing past a pair of heated side-by-side square cylinders, which is an extension part of our recent study [Sanyal, A. and Dhiman, A., “Wake interactions in a fluid flow past a pair of side-by-side square cylinders in presence of mixed convection,” Phys. Fluids 29, 103602 (2017)]. It is found that the leading-edge flow-separations from the square cylinders influence the near-wake structures and vortex shedding patterns in the presence of shear-thinning effects, which is otherwise missing for Newtonian fluid flow at Reynolds number Re = 40 and Richardson number Ri = 1. The distribution of wall-viscosity η along the inner surfaces of the side-by-side square cylinders, at different values of transverse spacings s/d and flow-behavior indices n, hints at large dependency on the inflections in the velocity profile within the gap-flow region. Under thermal buoyancy-driven mild shear-thinning flow conditions (n = 0.6 and 0.8), the gap-flow characteristics have been classified into “pressure-driven” and “momentum-driven” flow regimes, which provides a good explanation for the aberrations noted in the distribution pattern of η. The root-mean-square fluctuations of the velocity-magnitude and vortex shedding phenomenon are found to reciprocate a consistent flow physics associated with a shear-thinning flow at near and far-field downstream. The single body deflected type flow is primarily seen under predominant shear-thinning flow conditions (n = 0.4), compared to chaotic or quasi-periodic flow under mild shear-thinning conditions. Besides, the evolution of non-linear dynamics-based flow regimes (classified with respect to s/d using power spectrum density analysis) at different values of n and s/d is thoroughly summarized. The time-variant fluctuations of lift and drag force parameters are also found to be unified through cause and effects.
A diamond guard ring microdosimeter for ion beam therapy
Authors: Zahradnik I. A. , Barberet P. , Tromson D. , De Marzi L. , Pomorski M. T.
Published: May 2020

A single crystal chemical vapor deposition diamond-based microdosimeter prototype featuring an array of micro-sensitive volumes (μSVs) and surrounded by a so-called guard ring (GR) electrode has been fabricated using various microfabrication techniques available at Diamond Sensors Laboratory of CEA, Saclay. The GR microdosimeter was irradiated by a raster scanning method with 2 MeV proton microbeams. The charge transport properties of the GR sensor were determined with sub-micron spatial resolution by measuring the charge collection efficiency (CCE), the μSV geometry, and the pulse-height spectra. The response of the microdosimeter showed a well-defined and homogeneously active μSV. Appropriate biasing of the μSV structures led toward a full CCE for protons with lineal energies of ∼46 keV/μm. This shows the GR microdosimeter’s great potential for applications in microdosimetry in clinical beam conditions.