bluuebunny/crossref_metadata_2025 huggingface dataset:
Frakturen des distalen Radius
Authors: Konrads Christian , Gonser Christoph , Bahrs Christian
Published: July 2020

Zusammmenfassung

Die distale Radiusfraktur ist die häufigste Fraktur des Menschen. Das optimale Management dieser Verletzung erfordert umfassende Kenntnisse und Fähigkeiten hinsichtlich geschlossener und offener Repositionsmanöver, Gipstechnik und verschiedener Osteosynthesetechniken. Typische, aber auch seltene Begleitverletzungen müssen erkannt und in das Behandlungsregime einbezogen werden.
Second-Look Ultrasound Using Shear-Wave Elastography in MRI-Suspected Locoregional Recurrence of Breast Carcinoma
Authors: Divjak Eugen , Ivanac Gordana , Radović Niko , Biondić Špoljar Iva , Sović Slavica , Bahnik Valentina , Brkljačić Boris
Published: July 2020

Purpose To investigate if second-look US using shear-wave elastography (SWE) can help to differentiate between benign and malignant changes in the postoperative breast after surgical treatment of breast carcinoma.

Materials and Methods SWE and related sonographic features were reviewed in 90 female patients with a history of surgical treatment of breast carcinoma and a suspicious lesion detected on a follow-up MRI scan. A single experienced radiologist performed all second-look US exams with SWE measurements placing a circular region of interest measuring 2 mm in diameter over the stiffest part of the lesion. Tissue samples for histopathological analysis were obtained during the same US examination via core-needle biopsy.

Results Out of 90 lesions, 39 were proven malignant on histopathological analysis. 50 % of malignant lesions had Elmax values ranging from 128 to 199 kPa, and 50 % of benign lesions had Elmax values ranging from 65 to 169 kPa. The cut-off value of 171.2 kPa for Elmax shows a sensitivity of 59 % and specificity of 78.4 % for carcinoma recurrence, area under the curve 0.706 (CI95 % 0.6–0.81), P = 0.001. In univariate logistic models, restricted diffusion and stiffness on SWE, Elmax > 171.2 kPa, were shown as significant recurrence predictors. In the multivariate model, restricted diffusion remains significant independent recurrence predictor. With a recurrence prevalence of 43 %, the test sensitivity is 95 % (CI95 % 81–99 %) and the specificity is 75 % (CI95 % 60–85 %).

Conclusion Stiffer lesions should be considered suspicious on second-look US in the postoperative breast and SWE can be a helpful tool in identifying malignant lesions, especially if this is related to restricted diffusion on MRI exam. Lesion stiffness, however, should not be considered as an independent predictor of lesion malignancy in the postoperative breast, because of benign changes that can appear stiff on SWE, as well as carcinoma recurrences that may appear soft.
95 Jahre Universitäts-Hautklinik Jena – eine persönliche Betrachtung
Authors: Elsner P.
Published: July 2020

Die 95-jährige Geschichte der Universitäts-Hautklinik Jena ist nicht nur eine Geschichte dermatologischer Leistungen in Krankenversorgung, Forschung und Lehre. Sie ist auch eine Geschichte der Menschen, die diese Leistungen unter 3 politischen Systemen in Deutschland erbrachten und die Klinik gestalteten. Im historischen Rückblick wird deutlich, dass maßgebliche Repräsentanten der Klinik während des Nationalsozialismus in dessen Unrechtsregime verstrickt waren. Dies sollte Mahnung für nachgeborene Generationen sein, über ihre unmittelbare Verantwortung für die akademische Dermatologie hinaus wachsam zu bleiben gegenüber Einschränkungen von ärztlicher Freiheit und Grundrechten, aktuell durch die zunehmende Dominanz der Ökonomie in der Medizin.
Anti-Inflammatory Activity of the Compositae Family and Its Therapeutic Potential
Authors: Lopes Deise Cristina Drummond Xavier Paes , de Oliveira Temistocles Barroso , Viçosa Alessandra Lifsitch , Valverde Simone Sacramento , Ricci Júnior Eduardo
Published: July 2020

Compositae is the largest family of flowering plants, with more than 1600 genera and 22 000 species. It has many economic uses in foods, cosmetics, and pharmaceutics. The literature reports its numerous medicinal benefits and recognized anti-inflammatory activity. Thus, this study evaluated the technological trends of anti-inflammatory activity of Compositae, based on the survey of scientific databases, articles, and patents, as well as the website of the Brazilian National Health Regulatory Agency (ANVISA), which is responsible for registering and controlling of healthcare and cosmetic products in the Brazil. The survey was conducted between 2008 and 2018, in the databases Science Direct, Lilacs, PubMed, and Web of Science (main collection), as well as the SciELO Citation Index. The patent survey was carried out on the basis of the Derwent Innovations Index, an important source for worldwide patent consultation, which covers 20 y of registered patents. Despite the numerous studies involving species of the Compositae family in different models of anti-inflammatory activity, there are few records of patents or products on the market from these species for that purpose. Some species have a traditional use and are present even in the Phytotherapic Summary of the Brazilian Pharmacopeia. This review confirms the therapeutic potential of Compositae for the development of anti-inflammatory drugs and reinforces the need to develop competencies and reduce technological bottlenecks to promote research and innovation in biodiversity products.
Konzeption und Umsetzung eines Qualitätsmanagements für den ambulanten Rehabilitationssport bei Osteoporose in Bayern
Authors: Faul Martin , Kemmler Wolfgang
Published: July 2020

Rehabilitationssport und Funktionstraining sind das vorherrschende Setting für Bewegungsangebote zur Osteoporosetherapie und Frakturprävention. Ein zentrales Problem beider Formate ist das Fehlen eines Qualitätsmanagement-Konzepts (QM-Konzepts), in dem neben der Strukturqualität auch zentrale Aspekte der Prozess- und/oder Ergebnisqualität adressiert werden. Ziele des vorliegenden Projekts, das in Kooperation mit dem BVS Bayern e. V. durchgeführt wurde, waren daher (a) die detaillierte Umsetzung eines validierten Trainingsprotokolls in „Osteoporose“-Rehasportgruppen, (b) die Entwicklung eines QM-Konzepts, das insbesondere auf die Prozess- und Ergebnisqualität abhebt, und (c) die Weiterentwicklung/Anpassung/Optimierung des Konzepts.

Nach Evaluierung im Rahmen bestehender Rehabilitationssportgruppen in Bayern zeigte sich eine hohe Übertragbarkeit des wissenschaftlich evaluierten Trainingsprotokolls in die Trainingspraxis anerkannter Rehabilitationssportgruppen. Aus dem parallel validierten QM-Konzept wurde ein Qualitätssiegel ‚Sport pro Reha in Bayern‘ entwickelt, das an anerkannte Osteoporose-Rehabilitationssportgruppen, die am QM-Konzept des BVS Bayern teilnehmen, verliehen werden kann.
Expertentreffen COPD: Technologische Innovationen in der Pneumologie – Facetten aus Diagnostik und Therapie
Authors: Randerath W. , Dreher M. , Gompelmann D. , Held M. , Koczulla R. , Köhnlein T. , Rohde G. , Wälscher J. , Watz H. , Steinkamp G.
Published: July 2020

Ein wesentlicher Anteil der aktuellen technologischen Entwicklungen in der Pneumologie liegt in den verschiedenen Bereichen der Informationstechnologie. Das Spektrum reicht dabei von Smartphone-Apps, die im täglichen Leben oder der Praxis von Patienten oder Ärzten angewandt werden sollen, bis hin zum Einsatz der künstlichen Intelligenz in der Früherkennung. Die Diagnose-Genauigkeit von Apps zur Symptomanalyse ist dabei zurzeit noch sehr limitiert. Forschungsprojekte beschäftigen sich mit der Integration von Symptomen und Funktionsparametern in der Früherkennung, aber auch mit der Mobilitätserfassung als prognostischem Marker bei der COPD. Eine große Herausforderung stellt das Lungenkrebs-Screening mittels Computertomografie dar. Hier kann künstliche Intelligenz helfen, riesige Datenmengen zu bewältigen. Die Qualität hängt jedoch vom suffizienten Training der Systeme ab. Technologische Entwicklungen prägen alle Felder der Pneumologie. Sie erlauben in der diagnostischen und interventionellen Endoskopie die verbesserte Biopsietechnik und mikrostrukturelle Bildgebung. Methoden der Lungenfunktionsdiagnostik ermöglichen die differenzierte Analyse von atemmechanischen Störungen und können in die Beatmungstechnologie überführt werden. Die Translation von Grundlagenerkenntnissen zum Mikrobiom kann perspektivisch helfen, COPD-Exazerbationen besser zu verstehen und zielgerichteter zu behandeln.
Chemical Characterization of Lavandula dentata Essential Oil Cultivated in Chile and Its Antibiofilm Effect against Candida albicans
Authors: Müller-Sepúlveda Andrea , Chevecich Camila Cid , Jara José A. , Belmar Carolina , Sandoval Pablo , Meyer Rocío Santander , Quijada Raúl , Moura Sidnei , López-Muñoz Rodrigo , Díaz-Dosque Mario , Molina-Berríos Alfredo
Published: July 2020

Candida albicans is the most common human fungal pathogen, and with the increase in resistance rates worldwide, it is necessary to search for new pharmacological alternatives. Lavandula dentata L. essential oil is recognized as having antimicrobial properties. However, its effect against fungal biofilms has been poorly described. C. albicans-related infections involve the development of biofilms, which are highly resistant to conventional antifungals. In this work, we evaluated the antibiofilm effect of L. dentata L. essential oil against C. albicans. First, we characterized the essential oil by gas chromatography-mass spectrometry. The antifungal effect on C. albicans reference strains was evaluated by a disk diffusion assay and the minimal inhibitory concentration was obtained through a microdilution assay. The effect of the essential oil on the adhesion ability of C. albicans was determined through a crystal violet
assay, and morphogenesis inhibition was assessed by light microscopy. The effect of the essential oil on the microarchitecture of biofilms was evaluated through scanning electron microscopy. Finally, the antibiofilm effect was evaluated through an adapted biofilm scratch assay and XTT viability assay. The main constituent of the essential oil was the monoterpenoid eucalyptol (60%). The essential oil presented minimal inhibitory concentrations of 156 and 130 µg/mL against two strains assayed. This minimal inhibitory concentration inhibited adhesion, morphogenesis, biofilm formation, altered microarchitecture, and decreased the viability of established biofilms formed on abiotic surfaces for both strains assayed. This study demonstrates that the essential oil from L. dentata could be a promising treatment against C. albicans biofilms.
Estimation of [177Lu]PSMA-617 tumor uptake based on voxel-wise 3D Monte Carlo tumor dosimetry in patients with metastasized castration resistant prostate cancer
Authors: Götz Theresa Ida , Lang Elmar Wolfgang , Prante Olaf , Cordes Michael , Kuwert Torsten , Ritt Philipp , Ludwig Bernd , Schmidkonz Christian
Published: July 2020

Objective Patients with advanced prostate cancer are suitable candidates for [177Lu]PSMA-617 therapy. Integrated SPECT/CT systems have the potential to improve the accuracy of patient-specific tumor dosimetry. We present a novel patient-specific Monte Carlo based voxel-wise dosimetry approach to determine organ and total tumor doses (TTD).

Methods 13 patients with histologically confirmed metastasized castration-resistant prostate cancer were treated with a total of 18 cycles of [177Lu]PSMA-617 therapy. In each patient, dosimetry was performed after the first cycle of [177Lu]PSMA-617 therapy. Regions of interest were defined manually on the SPECT/CT images for the kidneys, spleen and all 295 PSMA-positive tumor lesions in the field of view. The absorbed dose to normal organs and to all tumor lesions were calculated by a three dimensional dosimetry method based on Monte Carlo Simulations.

Results The average dose values yielded the following results: 2.59 ± 0.63 Gy (1.67–3.92 Gy) for the kidneys, 0.79 ± 0.46 Gy (0.31–1.90 Gy) for the spleen and 11.00 ± 11.97 Gy (1.28–49.10 Gy) for all tracer-positive tumor lesions. A trend towards higher TTD was observed in patients with Gleason Scores > 8 compared to Gleason Scores ≤ 8 and in lymph node metastases compared to bone metastases. A significant correlation was determined between the serum-PSA level before RLT and the TTD (r = –0.57, p < 0.05), as well as between the TTD with the percentage change of serum-PSA levels before and after therapy was observed (r = –0.57, p < 0.05). Patients with higher total tumor volumes of PSMA-positive lesions demonstrated significantly lower kidney average dose values (r = –0.58, p < 0.05).

Conclusion The presented novel Monte Carlo based voxel-wise dosimetry calculates a patient specific whole-body dose distribution, thus taking into account individual anatomies and tissue compositions showing promising results for the estimation of radiation doses of normal organs and PSMA-positive tumor lesions.
N-Methylated 1,8-Diaminonaphthalenes as Bifunctional Nucleo­philes in Reactions with α,ω-Dihalogenoalkanes: A Facile Route to Heterocyclic and Double Proton Sponges
Authors: Ozeryanskii Valery A. , Kolupaeva Ekaterina V. , Pozharskii Alexander F.
Published: July 2020

The reaction of 1-dimethylamino-8-(methylamino)naphthalene with 1,3-dibromopropane chemoselectively leads to the product of N,N′-heterocyclization, while in the case of 1,4-dibromobutane and 1,2-bis(bromomethyl)benzene the process results in heterocyclization onto the same nitrogen atom with the formation of previously unknown 1-dimethylamino-8-pyrrolidino- and 1-dimethylamino-8-isoindolino-naphthalenes. The same reactions conducted without adding any auxiliary base lead to the formation of N,N′-linked double proton sponges as a new type of polynitrogen organic receptor. Proceeding as a sequence of quaternization–demethylation–cyclization steps, this heterocyclization process can also be used to construct six-membered rings (piperidino, morpholino), albeit in lower yields. The ability of 1,2-dibromoethane to brominate N-alkylated 1,8-diaminonaphthalenes is also described. It is shown for the first time that a commercially available 1,8-bis(dimethylamino)naphthalene (DMAN) can be used as a starting material in a heterocyclization reaction, which via a one-pot approach and in a short time can be converted into 1,5-dimethylnaphtho[1,8-bc]-1,5-diazacyclooctane or 1-dimethylamino-8-(pyrrolidin-1-yl)naphthalene.
Association of Anesthesia Type with Postoperative Outcome and Complications in Patients Undergoing Revision Total Knee Arthroplasty
Authors: Wei Chapman , Muthiah Arun , Gu Alex , Quan Theodore , Nguyen Kenneth T. , Fassihi Safa C. , Chen Aaron Z. , Amdur Richard L. , Nunley Ryan M. , Liu Jiabin , Sculco Peter K. , Berger Jeffrey S.
Published: July 2020

Revision total knee arthroplasty (TKA) is an increasingly common procedure and is effective in treating knee osteoarthritis, but it has higher complication rates than primary TKA. Anesthetic choice poses perioperative risk that has been extensively studied in primary TKA, showing favorable results for regional anesthesia compared with general anesthesia. The impact of anesthetic choice in revision TKAs is not well studied. A retrospective cohort study was conducted using the American College of Surgeons National Surgical Quality Improvement Program database. Patients who underwent revision TKAs between 2014 and 2017 were divided into three anesthesia cohorts: (1) general anesthesia, (2) regional anesthesia, and (3) combined general-regional anesthesia. Univariate and multivariate analyses were used to analyze patient characteristics and 30-day postoperative outcomes. Bonferroni correction was applied for post hoc analysis. In total, 8,820 patients were identified. Of whom, 3,192 patients underwent general anesthesia, 3,474 patients underwent regional anesthesia, and 2,154 patients underwent combined anesthesia. After multivariate analyses, regional anesthesia was associated with decreased odds for any complication (p = 0.008), perioperative blood transfusion (p < 0.001), and extended length of stay (p < 0.001) compared with general anesthesia. In addition, regional anesthesia was associated with decreased odds for perioperative blood transfusion (p < 0.001) and extended length of stay (p = 0.006) compared with combined anesthesia. However, following multivariate analysis, regional anesthesia was not associated with decreased odds of wound, pulmonary, renal, urinary tract, thromboembolic, and cardiac complications, and was not associated with return to operating room, extended length of stay, minor and major complications, and mortality. Retrospective analysis of a large surgical database suggests that patients receiving general anesthesia have increased likelihood for developing adverse postoperative outcomes relative to patients receiving regional anesthesia. Prospective and controlled trials should be conducted to verify these findings.
The Effect of Patellar Positioning on Femoral Component Rotation when Performing Flexion Gap Balancing Using a Tensioning Device for Total Knee Arthroplasty
Authors: Ernstbrunner Lukas , Andronic Octavian , Grubhofer Florian , Jundt-Ecker Michèle , Fucentese Sandro F.
Published: July 2020

There is an increasing interest in new devices such as tensiometers for flexion gap balancing during total knee arthroplasty (TKA). The purpose of this study was to determine the influence of patella positioning during flexion gap balancing on femoral component rotation. We prospectively evaluated 32 consecutive knees in 31 patients who underwent primary TKA for degenerative osteoarthritis and where soft tissue balancing was performed using the same tensiometer. Preoperative measurements included valgus/varus deformation, mechanical axis, epicondylar axis, and tibial slope. Intraoperatively, measurement of femoral component rotation in 90 degrees of knee flexion was conducted in three different positions of the patella: (1) patella reduced, (2) patella dislocated but not everted, and (3) patella dislocated and everted. The femoral component had significantly higher rotation when the patella was reduced compared with a dislocated patella (4.9 ± 2.1 degrees vs. 4.2 ± 2.2 degrees; p = 0.006) and compared with a dislocated and everted patella (4.9 ± 2.1 degrees vs. 4.1 ± 2.3 degrees; p = 0.006). Varus knees (n = 22) demonstrated significantly increased femoral component rotation if the patella was reduced (5.3 ± 2.2 degrees) compared with dislocated patella without eversion (4.7 ± 2.3 degrees; p = 0.037) and with eversion (4.4 ± 2.5 degrees; p = 0.019). As such, the measurement of the mediolateral flexion gap stability with a laterally dislocated patella leads to a statistically significant overestimation of the lateral ligament stability and an underestimation of the external rotation positioning of the femoral component of approximately 1 degree, which is aggravated in varus knees. This is a Level II, prospective consecutive series study.
The COVID-19 Pandemic: A View from New York City
Authors: Masiello Domenick J.
Published: July 2020

This article provides a view of homeopathic clinical practice in the New York City area in the first few months of 2020 as the coronavirus disease 2019 (COVID-19) pandemic began to evolve in the United States. Key symptoms used to generate a short list of potentially curative remedies are given, and the pandemic syndrome is viewed as appearing in stages or as having various clinical manifestations each with its own main remedy. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is briefly described, as are the preliminary presenting signs and symptoms of COVID-19 infection. Several clinical examples are given, some with positive laboratory confirmation.
Through thick and thin: Russia, China and the future of Eurasian International Society
Authors: Paikin Zachary
Published: July 2020

Recent years have seen Moscow and Beijing driven closer together as their respective relations with Washington have deteriorated. While a normative convergence between Russia and China appears to be underway, there remains a legacy of historical mistrust in addition to potential irritants that could plague their bilateral relationship. Nonetheless, if Western sanctions against Russia and pressure on China continue unabated, they may have little option but to continue their rapprochement. Against this backdrop, this article will explore whether the two countries currently display a ‘thin’ or ‘thick’ bilateral relationship, making use of an English School theoretical framework. It will do so by exploring established English School concepts such as pluralism and solidarism and discussing notable literature within the School on contestation in order to derive conclusions regarding the potential future shape of international order in Eurasia.
Russia between east and west, and the future of Eurasian order
Authors: Korosteleva Elena , Paikin Zachary
Published: July 2020

This article introduces the special issue by going beyond the traditional debates about geopolitics and great power rivalry. Instead, it examines the emergent and highly complex world of Central Eurasia, in its transformative effort to reorder itself in response to both global and local change. In particular, the paper (and the volume) focuses on two interrelated themes: one of a changing Russia, that is anxiously trying to adapt to the uncertain dynamics within and beyond the wider Eurasian space; and the other—of an emerging complexity of new order-making regional (integration) initiatives that are poised to reshape the future of international and global order. The overarching intention of this paper and the volume is to advance the need to focus on ‘the local’, to gain a more holistic understanding of the present-day challenges and the kind of global response needed to stay attuned to the increasingly complex world.
How to hijack a discourse? Reflections on the concepts of post-truth and fake news
Authors: Krasni Jan
Published: July 2020

The aim of this paper is threefold: to perform a (meta)discursive archaeology of the concepts post-truth and fake news, to critically reflect on the change in the application of these concepts between the various domains of discourse such as public intellectual field or academic research and mainstream media, and finally to show how the concept of post-truth is now used against the very intellectual milieu it originates from. Whereas the first objective deals with the historical reconceptualization process, the second shows—drawing on the case of social networks—how the concept of fake news infects topics of public relevance, while the third demonstrates how ubiquitous the critique of the left and postmodern intellectual tradition is. This paper combines Foucault’s and Agamben’s approaches to reconstruct the changes and evolution of the concept and the knowledge that defines it. It considers various sources in which this discourse exists regardless of their ideological background—from intellectual discussions on its formation and critiques of the phenomenon it stands for, to journalistic materials which constitute the body of post-truth and fake news discourse today.
Improved activity and stability of Ag–Rh network-like nanoalloy as support-free electrocatalyst for oxygen reduction in alkaline fuel cells
Authors: Bhuvanendran Narayanamoorthy , Balaji Subramanian , Zhang Weiqi , Xu Qian , Pasupathi Sivakumar , Su Huaneng
Published: July 2020

In this study, a simple and environmentally amicable synthesis procedure for support-free silver–rhodium (Ag–Rh) bimetallic network-like nanoalloy was used to catalyze an oxygen reduction reaction in an alkaline medium. The support-free network-like morphology of Ag–Rh nanoalloy exhibits a higher electrochemical surface area (ECSA) of 65.6 m2/g than carbon (VC) supported Ag–Rh (23.8 m2/g). In comparison to the reported benchmark Ag-based electrocatalysts, it presents an improved mass and specific activity of 971.1 mA/mg and 1.45 mA/cm2, respectively. Based on the durability test, the support-free Ag–Rh catalyst retains ∼70% of its initial ECSA after 7000 potential cycles, and Ag–Rh/VC possesses only 20% after 5000 potential cycles due to the surface oxidation of carbon support. Hence, the superior electrocatalytic performance attributed to the support-free morphology and alloy formation with Rh was clearly demonstrated, which could potentially be the choice of the cathodic electrocatalyst for alkaline fuel cells.
Structural, transport, optical, and electronic properties of Sr2CoNbO6 thin films
Authors: Kumar Ajay , Shukla Rishabh , Pandey Akhilesh , Dalal Sandeep , Miryala M. , Ueno K. , Murakami M. , Dhaka R. S.
Published: July 2020

We study the effect of substrate induced strain on the structural, transport, optical, and electronic properties of Sr2CoNbO6 double perovskite thin films. The reciprocal space mapping, ϕ-scan, and high-resolution θ–2θ scans of x-ray diffraction patterns suggest the epitaxial nature and high-quality of the films deposited on various single crystal ceramic substrates. A systematic enhancement in the dc electronic conductivity is observed with an increase in the compressive strain while there is a sharp reduction in the case of tensile strain, which is further supported by a change in the activation energy and the density of states near the Fermi level. The optical bandgap extracted from two distinct absorption bands, observed in the visible–near infrared spectroscopy, shows a non-monotonic behavior in the case of compressive strain while there is significant enhancement with tensile strain. Unlike the bulk Sr2CoNbO6 (Co3+ and Nb5+), we observe different valence states of Co, namely, 2+, 3+, and 4+, and tetravalent Nb (4d1) in the x-ray photoemission spectroscopy measurements. Moreover, a reduction in the average oxygen valency with the compressive strain due to enhancement in the covalent character of Co/Nb–O bond is evident. Interestingly, we observe sharp Raman active modes in these thin films, which indicates a significant enhancement in structural ordering as compared to the bulk.
Defect properties of solar cells with layers of GaP based dilute nitrides grown by molecular beam epitaxy
Authors: Baranov Artem I. , Gudovskikh Alexander S. , Egorov Anton Yu. , Kudryashov Dmitry A. , Le Gall Sylvain , Kleider Jean-Paul
Published: July 2020

Dilute nitrides lattice-matched to GaP were studied to explore the possibilities to improve their properties by additional indium or arsenic content in the GaPN alloy for further utilization in solar cells. Admittance spectroscopy shows that intrinsic layers of GaPNAs and InP/GaPN grown by molecular-beam epitaxy have unintentional background silicon donor doping. Deep-level transient spectroscopy allowed us to reveal several defect levels. In GaPNAs, two defect levels were detected at Ec − 0.58 eV and Ev + 0.44 eV, with respective concentrations of 4 × 1015 cm−3 and 2 × 1015 cm−3. After thermal annealing, these could be reduced by a factor of two and by more than one order of magnitude, respectively, leading to an increase of external quantum efficiency and open-circuit voltage of solar cells. The InP/GaPN layer exhibits a defect level at Ec − 0.44 eV (with a concentration of 2 × 1014 cm−3), which is of similar nature as the one at Ec − 0.58 eV in GaPNAs. Furthermore, unlike in GaPNAs, defect levels close to midgap were also detected in the InP/GaPN layer. These non-radiative recombination centers lead to poorer photoelectric properties of solar cells based on InP/GaPN as compared to those based on GaPNAs. Therefore, the introduction of arsenic in the compound and post-growth thermal annealing allowed us to reduce the defect concentrations in dilute nitrides and improve photoelectrical properties for photovoltaic applications.
Antisite disorder driven magnetodielectric and magnetocaloric effect in double perovskite La2−xSrxCoMnO6 (x = 0.0, 0.5, 1.0)
Authors: Mandal P. R. , Khan Anasua , Nath T. K.
Published: July 2020

We report magnetic, dielectric, magnetodielectric, and magnetocaloric responses of La2CoMnO6 (LCMO) and Sr doped La2−xSrxCoMnO6 (x = 0.5 and 1.0) induced by antisite disorder. The antisite disorder is enhanced with Sr-doping at La-sites. Co ions have mixed valence states on Sr-doping, with Co3+ and Co2+. Mn is present in mixed valence of Mn4+ and Mn3+ states with Sr doping. The dielectric constant of Sr doped LCMO was found to increase, whereas the magnetodielectric coupling was found suppressed due to the increase of antisite disorder. The magnetic field-dependent magnetodielectric effect clearly shows M2 behavior for all the samples in the field range of 0 to ±6 T in their respective ferroic phases. All the samples show spin glass like ordering in the ground state. We also report the magnetic entropy change in magnetoelectric material La2−xSrxCoMnO6 (x = 0, 1.0) samples. The change in magnetic entropy ΔSm originates mainly from the combined effect of the ferromagnetic/antiferromagnetic interaction and the magnetodielectric effect in La2−xSrxCoMnO6 (x = 0, 1.0). The observed value of the magnetocaloric effect (1.2 J/kg K) for x = 1.0 is likely to originate from the antisite disordered phases near Curie temperature.
Recombination-enhanced dislocation climb in InAs quantum dot lasers on silicon
Authors: Mukherjee Kunal , Selvidge Jennifer , Jung Daehwan , Norman Justin , Taylor Aidan A. , Salmon Mike , Liu Alan Y. , Bowers John E. , Herrick Robert W.
Published: July 2020

We analyze the structure of dislocations in electrically aged InAs quantum dot (QD) lasers on silicon to understand gradual device degradation. We find that misfit dislocations lengthen due to carrier injection, experiencing a combination of recombination-enhanced climb and glide processes constrained by the epitaxial structure. An examination of the dislocation geometry reveals that the climb process involves the addition of atoms to the extra half plane of the dislocation. Spontaneous emission from the QDs is also dimmer after aging. Additionally, the signature of misfit dislocations in the unaged laser, discernible as sharp dark lines in spatially resolved cathodoluminescence, is replaced by finer, more inhomogeneous contrast upon aging. We speculate that this change arises from vacancy clouds expelled from the dislocation during climb. With this insight, we evaluate the driving forces for dislocation climb that could be at play and discuss the origins of slow degradation in QD lasers.
Discharge characteristics and increased electron current during azimuthally nonuniform propellant supply in an anode layer Hall thruster
Authors: Bak J. , Van Loo B. , Kawashima R. , Komurasaki K.
Published: July 2020

Discharge current components, such as electron, ion beam, and lost-to-wall currents, are obtained as functions of azimuthal propellant inhomogeneity in a Hall thruster. Discharge characteristics are discussed based on discharge current oscillation and radial–azimuthal discharge photography. A highly oscillative operation regime is found to be accompanied by radially enlarged expansion of discharge under limited electron currents. Further increases in neutral inhomogeneity lead to quiescent discharge combined with enhanced electron currents and an azimuthally separated ionization region. An axial one-dimensional classical view of electron flow is found to explain the observed electron current evolution only until moderate propellant inhomogeneity occurs. Through discharge image analysis, it is shown that plasma inhomogeneity increases linearly with respect to the input neutral particle inhomogeneity. The evolution of the inhomogeneity does not capture a stepwise increase in the electron current during discharge mode changes; however, the monotonic increase featured in each discharge regime shows that the azimuthal gradient of plasma properties can contribute to increased electron current. Lastly, the weakened magnetic barrier to electron flow resulting from axial–azimuthal variation in plasma structures is presented as another possible cause of increased electron current in nonuniform propellant operations.
Spacetime groups
Authors: Anderson Ian , Torre Charles
Published: July 2020

A spacetime group is a connected 4-dimensional Lie group G endowed with a left invariant Lorentz metric h such that the connected component of the isometry group of h is G itself. The Newman–Penrose formalism is used to give an algebraic classification of spacetime groups, that is, we determine a complete list of inequivalent spacetime Lie algebras, which are pairs (g,η), with g being a 4-dimensional Lie algebra and η being a Lorentzian inner product on g. A full analysis of the equivalence problem for spacetime Lie algebras is given, which leads to a completely algorithmic solution to the problem of determining when two spacetime Lie algebras are isomorphic. The utility of our classification is demonstrated by a number of applications. The results of a detailed study of the Einstein field equations for various matter fields on spacetime groups are given, which resolve a number of open cases in the literature. The possible Petrov types of spacetime groups that, generically, are algebraically special are completely characterized. Several examples of conformally Einstein spacetime groups are exhibited. Finally, we describe some novel features of a software package created to support the computations and applications of this paper.
Radiation and chemical reactive impact on tangent hyperbolic fluid flow having double stratification
Authors: Khan Mumtaz , Rasheed Amer , Salahuddin Taimoor
Published: July 2020

In real life, chemically reactive mixtures occur in many situations such as in chemically engineered products, combustion, and many more. The aim of this study is to analyze the flow, heat, and mass transfer analysis of chemically reactive mixed convective flow of hyperbolic tangent fluid having thermal radiation and viscous dissipation in a doubly stratified medium. Appropriate transformations are capitalized to transform the set of partial differential equations into the set of ordinary differential equations (ODEs). A highly efficient BVPh2.0 solver, which is based on the homotopy analysis method, is employed to solve the set of ODEs. The convergence of BVPh2.0 is demonstrated by average- and total-squared residual errors. Finally, the obtained results for velocity, temperature, concentration, skin friction coefficient, and local Nusselt and Sherwood numbers are analyzed by means of graphs and tables. A decrease in the skin friction coefficient Cf corresponding to an increase in the values of the power law index n is noticed. However, an opposite behavior is noticed in the case of the chemical reaction parameter γ. By increasing the Prandtl number Pr, the local Nusselt number shows an increasing behavior while the Sherwood number shows a decreasing behavior. On the other hand, both the local Nusselt and Sherwood numbers show an increasing behavior in the case of the radiation parameter.
Fabrication of non-magnetic multi-pin coaxial vacuum feedthrough system for cryogenic applications
Authors: Sikdar A. K. , Nandi J. , Das P. , Ray A.
Published: July 2020

We have developed and tested a compact non-magnetic feedthrough made of epoxy resin and capable of maintaining vacuum leak tightness over a wide temperature range (300 K–4 K). It is equipped with 15 electrical pins and three 50 Ω coaxial lines. The feedthrough has been designed to apply a high voltage (up to 5 kV) and transmit radio-frequency signals for operating a Penning trap over a wide temperature range (300 K–4 K). The characteristic impedances of the coaxial lines have been measured at 300 K and 77 K and found to remain ∼50 Ω over the frequency range of our interest (10 MHz–80 MHz). The details of its fabrication and performance over a wide temperature range have been discussed.
Effects of disorder on magnetotransport oscillations in a two-dimensional electron gas terminated by superconductors
Authors: Takagaki Y.
Published: July 2020

The coupling of superconductivity in a two-dimensional electron gas (2DEG) generates a number of magnetotransport oscillations. For instance, an Aharonov–Bohm-type oscillation at intermediate magnetic fields and an Altshuler–Aronov–Spivak-like oscillation around zero magnetic field appear under the circumstance of the coexistence of Andreev and normal reflections from the interface between the normal-conductor and the superconductor. The presence and the characteristics of such magnetotransport oscillations are investigated in this work by carrying out fully quantum-mechanical simulations. The significant role of the quantum interference is thereby demonstrated. It is also shown how the oscillations are affected by the presence of a potential disorder and finite excitation biases. Shubnikow–de Haas oscillations of the 2DEG are not always suppressed by the disorder under the influence of superconductivity, making their distinction from the Aharonov–Bohm-type oscillation possibly ambiguous.
Computational fluid dynamics analysis of char conversion in Sandia’s pressurized entrained flow reactor
Authors: Bösenhofer Markus , Hecht Ethan , Shaddix Christopher R. , König Bernhard , Rieger Johannes , Harasek Michael
Published: July 2020

Design and analysis of practical reactors utilizing solid feedstocks rely on reaction rate parameters that are typically generated in lab-scale reactors. Evaluation of the reaction rate information often relies on assumptions of uniform temperature, velocity, and species distributions in the reactor, in lieu of detailed measurements that provide local information. This assumption might be a source of substantial error, since reactor designs can impose significant inhomogeneities, leading to data misinterpretation. Spatially resolved reactor simulations help understand the key processes within the reactor and support the identification of severe variations of temperature, velocity, and species distributions. In this work, Sandia’s pressurized entrained flow reactor is modeled to identify inhomogeneities in the reaction zone. Tracer particles are tracked through the reactor to estimate the residence times and burnout ratio of introduced coal char particles in gasifying environments. The results reveal a complex mixing environment for the cool gas and particles entering the reactor along the centerline and the main high-speed hot gas reactor flow. Furthermore, the computational fluid dynamics (CFD) results show that flow asymmetries are introduced through the use of a horizontal gas pre-heating section that connects to the vertical reactor tube. Computed particle temperatures and residence times in the reactor differ substantially from the idealized plug flow conditions typically evoked in interpreting experimental measurements. Furthermore, experimental measurements and CFD analysis of heat flow through porous refractory insulation suggest that for the investigated conditions (1350 °C, <20 atm), the thermal conductivity of the insulation does not increase substantially with increasing pressure.
Multi-pass relativistic traveling-wave tube with simultaneous operation on symmetric and asymmetric modes
Authors: Abubakirov E. B. , Konyushkov A. P. , Leontyev A. N. , Rozental R. M. , Tarakanov V. P.
Published: July 2020

The advantages of using symmetrical and asymmetric eigenmodes of a slow-wave system (SWS) in a relativistic traveling-wave tube (TWT) with multi-pass amplification are discussed. The nonlinear theory of such a TWT amplifier is developed. The parameters of the SWS of the Ka-band TWT amplifier based on a combination of the lower symmetric E01 mode and the asymmetric hybrid HE11 mode are calculated. The calculated efficiency of the amplifier reaches 28% with a gain of about 40 dB. The results of the calculations are confirmed by 3D particle-in-cell (PIC) simulation, in which an output power of 200 MW and a total gain of about 40 dB are obtained when the amplifier is driven by a 500 keV/2 kA hollow electron beam with a total pulse duration of 25 ns. Amplification of short millimeter-wave pulses is also demonstrated in PIC simulations, in which an output peak power of about 180 MW with a pulse duration of the order of 1 ns is obtained.
Multiple coupled charge layers in electron beam induced charging phenomenon
Authors: Li C. , Li H. M. , Ding Z. J.
Published: July 2020

We report a discovery of the multiple coupled charge layer phenomenon in an insulating solid, SiO2, when irradiated by an electron beam with the aid of a Monte Carlo method. In tracing the transporting electrons, their encountered elastic, inelastic, and phonon scatterings, in conjunction with the influence of the electric field, are incorporated to model their transport more accurately. In handling charging, we consider the trapping of holes and energy-exhausted electrons on their drift paths, with the use of the electric-field-dependent drift velocity and trapping cross section. The emission of secondary electrons is modified by considering their trapping on the emission paths. Besides, the trapped charges may become detrapped under the electric field, which is also taken into account. Totally, six (three coupled) alternating charge layers are formed, with each layer having a thickness of about 0.1 μm, being parallel to the sample surface and existing merely along the beam incidence axis. The first layer is positive and is formed by secondary electron emission, while the sixth layer is negative and is formed by the extensive trapping of primary electrons. The middle four layers are formed by charge drift, in which electrons and holes move to opposite directions. However, the layer number remains unchanged with the increasing primary energy, since the charging involved in the simulation is negative, in which the primary electrons of different energies would be decelerated to a similar landing energy of 2–3 keV.
Super-Planckian radiative heat transfer between macroscale metallic surfaces due to near-field and thin-film effects
Authors: Sabbaghi Payam , Long Linshuang , Ying Xiaoyan , Lambert Lee , Taylor Sydney , Messner Christian , Wang Liping
Published: July 2020

In this study, we demonstrate that the radiative heat transfer between metallic planar surfaces exceeds the blackbody limit by employing the near-field and thin-film effects over macroscale surfaces. Nanosized polystyrene particles were used to create a nanometer gap between aluminum thin films of different thicknesses from 80 nm to 13 nm coated on 5 × 5 mm2 silicon chips, while the vacuum gap spacing is fitted from the near-field measurement with bare silicon samples. The near-field radiative heat flux between 13-nm-thick Al thin films at 215 nm gap distance is measured to be 6.4 times over the blackbody limit and 420 times to the far-field radiative heat transfer between metallic surfaces under a temperature difference of 65 K with the receiver at room temperature. The experimental results are validated by theoretical calculation based on fluctuational electrodynamics, and the heat enhancement is explained by non-resonant electromagnetic coupling within the subwavelength vacuum gap and resonant coupling inside the nanometric Al thin film with s polarized waves. This work will facilitate the applications of near-field radiation in thermal power conversion, radiative refrigeration, and noncontact heat control where metallic materials are involved.
Scalable production of solid-immersion lenses for quantum emitters in silicon carbide
Authors: Sardi F. , Kornher T. , Widmann M. , Kolesov R. , Schiller F. , Reindl T. , Hagel M. , Wrachtrup J.
Published: July 2020

4H–silicon carbide (SiC) shows the capability of hosting a large number of promising emitters for quantum technology. However, due to its high refractive index, the collection of photoluminescence emission is compromised for further applications. Here, we demonstrate a scalable approach of manufacturing solid-immersion lenses (SILs) on 4H–SiC. The procedure results in SILs with high effective NA. The fluorescence collection efficiency of single quantum emitters under the SILs shows 3.4 times enhancement confirmed by confocal microscopy of individual V2.
Organ-on-a-chip engineering: Toward bridging the gap between lab and industry
Authors: Ramadan Qasem , Zourob Mohammed
Published: July 2020

Organ-on-a-chip (OOC) is a very ambitious emerging technology with a high potential to revolutionize many medical and industrial sectors, particularly in preclinical-to-clinical translation in the pharmaceutical arena. In vivo, the function of the organ(s) is orchestrated by a complex cellular structure and physiochemical factors within the extracellular matrix and secreted by various types of cells. The trend in in vitro modeling is to simplify the complex anatomy of the human organ(s) to the minimal essential cellular structure “micro-anatomy” instead of recapitulating the full cellular milieu that enables studying the absorption, metabolism, as well as the mechanistic investigation of drug compounds in a “systemic manner.” However, in order to reflect the human physiology in vitro and hence to be able to bridge the gap between the in vivo and in vitro data, simplification should not compromise the physiological relevance. Engineering principles have long been applied to solve medical challenges, and at this stage of organ-on-a-chip technology development, the work of biomedical engineers, focusing on device engineering, is more important than ever to accelerate the technology transfer from the academic lab bench to specialized product development institutions and to the increasingly demanding market. In this paper, instead of presenting a narrative review of the literature, we systemically present a synthesis of the best available organ-on-a-chip technology from what is found, what has been achieved, and what yet needs to be done. We emphasized mainly on the requirements of a “good in vitro model that meets the industrial need” in terms of the structure (micro-anatomy), functions (micro-physiology), and characteristics of the device that hosts the biological model. Finally, we discuss the biological model–device integration supported by an example and the major challenges that delay the OOC technology transfer to the industry and recommended possible options to realize a functional organ-on-a-chip system.
Study of ferroelectric characteristics of Hf0.5Zr0.5O2 thin films grown on sputtered or atomic-layer-deposited TiN bottom electrodes
Authors: Kim Beom Yong , Kim Baek Su , Hyun Seung Dam , Kim Ho Hyun , Lee Yong Bin , Park Hyun Woo , Park Min Hyuk , Hwang Cheol Seong
Published: July 2020

Ferroelectric Hf0.5Zr0.5O2 (HZO) films were grown by the atomic layer deposition (ALD) technique on an ALD or physical-vapor-deposited (PVD, sputtering) TiN bottom electrode (BE). The PVD TiN film showed small grains with flat surface morphology, mainly consisting of the (111) crystallographic plane. In contrast, the ALD TiN film exhibited a larger diameter and faceted grain shapes, with the (200) crystallographic surface planes. The 10-nm-thick HZO film on the ALD TiN BE showed a lower internal field, enhanced endurance (>1 × 1010 cycle at 2.5 MV/cm), and decreased leakage current than identical HZO films on the PVD TiN BE. Lower interfacial oxidation of the ALD TiN BE as a result of the smaller grain boundary area of the ALD TiN induced a lower defect density in the HZO film. The higher work function of the ALD TiN film also contributed to the lowering of the leakage current.