bluuebunny/crossref_metadata_2025 huggingface dataset:
Transkutane osseointegrierte Prothesensysteme (TOPS) zur Versorgung
Oberschenkelamputierter
Authors: Ranker Alexander , Örgel Marcus , Beck James Peter , Krettek Christian , Aschoff Horst Heinrich
Published: September 2020

Ziel Der Studie Durchgeführt wurde eine retrospektive Analyse der
klinischen Ergebnisse und Komplikationsraten aller oberschenkelamputierten
Patienten eines Zentrums, die mit dem neuesten Implantatdesign der sogenannten
Endo-Exo-Femur-Prothese (EEFP, dritte Generation) versorgt wurden. Ziel ist es,
spezifische Informationen zu Langzeitkomplikationen dieser
Amputationsversorgungsform zu gewinnen.

Methodik Im Januar 2019 wurden Daten aller Oberschenkelamputierten, die
von 2010 bis 2016 an einer Akutklinik aus Schleswig-Holstein mit TOPS versorgt
wurden, retrospektiv analysiert. Dies geschah unter besonderer
Berücksichtigung der postoperativen Komplikationen. Hierfür
wurden alle Untersuchungsbefunde der klinischen Routine-Nachsorge-Untersuchungen
herangezogen. Die Komplikationen wurden unterteilt in Stomaprobleme,
orthopädie-technische Probleme, Frakturen und Explantationen. Alle EEFPs
besaßen das gleiche Implantatdesign (dritte Generation). Dieses
Implantat findet derzeit als einziges TOPS in Deutschland klinische Anwendung.
Eine deskriptive Statistik des Patientenkollektivs, sowie
Verhältnisangaben über aufgetretene Komplikationen wurden
berechnet.

Ergebnisse Insgesamt wurden in diesem Zeitraum 68 Implantationen
durchgeführt. Durchschnittliche Beobachtungszeit war 6,32 Jahre
(±2,16 Jahre). Das mittlere Alter der Patienten betrug 51,84
Jahre±12,12 Jahre. Ursache der Amputation waren überwiegend
Traumata (82,35%). Stoma-assoziierte Probleme zeigten mit 7% die
höchste Inzidenz innerhalb aller beobachteten, patientenassoziierten
Komplikationen und stellten die größten Herausforderungen
während des Rehabilitationsprozesses dar. Betrachtet man nur die
chirurgischen Komplikationen, so hatten 81% überhaupt keine
Komplikationen. Insgesamt wiesen 15% orthopädie-technische
Probleme auf, 6% eine peri-prothetische Fraktur, 7% Probleme am
Stoma und 3% mussten aufgrund einer Infektion explantiert werden.

Schlussfolgerung Die erhobene Datenanalyse zeigt, dass TOPS (hier die
EEFP der dritten Generation) eine erfolgreiche alternative Behandlungsmethode
zur Schaftprothesenversorgung für Patienten mit
Oberschenkelknochenverlust darstellen können. Die Indikation sollte erst
nach dem Versagen einer Schaftversorgung erfolgen und Kontraindikationen
müssen umfassend ausgeschlossen werden. Die größten
Herausforderungen im Rehabilitationsprozess stellen die Vermeidung von
Stomakomplikationen, Infektionen und orthopädie-technischen Problemen
dar. Die Rehabilitation von Amputierten, die mit TOPS behandelt werden,
erfordert daher ein interdisziplinäres, spezialisiertes
Rehabilitations-Team und eine lebenslange rehabilitative Versorgung.
Recent Developments on Denitrogenative Functionalization of Benzotriazoles
Authors: Yan Guobing , Tiwari Vinod K. , Yu Jie , Singh Anoop S. , Yu Jian
Published: September 2020

Benzotriazoles are employed as useful synthons in organic synthesis, and due to their unique structural motif, they are able to undergo denitrogenation during the construction of new bonds. Various methods for the functionalization of benzotriazoles as precursors of ­ortho-amino arenediazoniums have recently been developed that involve transition-metal-catalyzed coupling reactions, mainly via cyclization, borylation, alkenylation, alkylation, carbonylation and the formation of carbon–heteroatom bonds. In this short review, we primarily focus on the recent applications of benzotriazoles in organic chemistry that proceed via a denitrogenative process, and the mechanisms are also discussed.

1 Introduction

2 Common Synthetic Routes Allowing Easy Access to Benzotriazole Derivatives

3 Formation of C–C Bonds

3.1 Cyclization Reactions

3.2 Arylation, Alkenylation, Alkylation and Carbonylation Reactions

4 Carbon–Heteroatom Bond Formation

5 Miscellaneous Denitrogenative Functionalization

6 Conclusions and Future Perspectives
Patellofemoral Arthroplasty Improves Patellofemoral Alignment in Patients with Patellofemoral Osteoarthritis with Trochlear Dysplasia
Authors: Yang Guangmin , Wang Jue , Dai Yike , Lin Wei , Niu Jinghui , Wang Fei
Published: September 2020

The impact of trochlear dysplasia on patellofemoral arthroplasty (PFA) has rarely been reported in the literature. The purpose of this study was to explore the effectiveness of PFA in patients with patellofemoral osteoarthritis (PFOA) associated with trochlear dysplasia. From January 2014 to March 2018, 35 patients with PFOA and trochlear dysplasia (29 females and 6 males), underwent PFA, were included in the present retrospective study. Radiological measurements including the patellar tilt (PT), congruence angle (CA), Blackburne–Peel ratio (BPR), tibial tuberosity–trochlear groove (TT–TG) distance, and lateral trochlear inclination (LTI) were assessed pre- and postoperatively to evaluate the changes in patellofemoral alignment. The patient-reported functional outcome was assessed using the Oxford Knee Score. The mean follow-up time was 24 months (range, 18–42 months). The intraclass correlation coefficients were excellent for all measurements. The patellofemoral alignment and knee function were significantly improved postoperatively. The PT decreased from 23.3 ± 6.3 degrees preoperatively to 6.4 ± 2.3 degrees postoperatively (p < 0.001). The CA decreased from 32.3 ± 8.6 degrees preoperatively to 10.2 ± 3.6 degrees postoperatively (p < 0.001). The lateral trochlear inclination increased from 8.3 ± 4.1 degrees preoperatively to 16.0 ± 1.2 degrees postoperatively (p < 0.001). The TT–TG distance decreased from 18.2 ± 3.8 mm preoperatively to 11.5 ± 3.3 mm postoperatively (p < 0.001). The BPR did not significantly change postoperatively (p = 0.390). The average Oxford Knee Score improved from 19.5 preoperatively to 29.2 at 6 months postoperatively (p < 0.001), 37.9 at 1 year postoperatively (p < 0.001), and 39.1 at final follow-up (p < 0.001). No patient developed patellofemoral malalignment or prosthesis loosening during short-term follow-up. PFA achieved favorable therapeutic results in patients with PFOA associated with trochlear dysplasia.
Innovation in Community Psychiatry for the Delivery of Mental Health Services: The Sawangi Model
Authors: Behere Prakash B. , Nagdive Amit B. , Behere Aniruddh P. , Yadav Richa , Fernandes Rouchelle
Published: September 2020

Objectives Can undergraduate medical students (UGs) adopt a village model to identify mentally ill persons in an adopted village successfully?

Materials and Methods UGs during their first year adopt a village, and each student adopts seven families in the villages. During the visit, they look after immunization, tobacco and alcohol abuse, nutrition, hygiene, and sanitation. They help in identifying the health needs (including mental health) of the adopted family. The Indian Psychiatric Survey Schedule containing 15 questions covering most of the psychiatric illnesses were used by UGs to identify mental illness in the community. Persons identified as suffering from mental illness were referred to a consultant psychiatrist for confirmation of diagnosis and further management.

Statistical Analysis  Calculated by percentage of expected mentally ill persons based on prevalence of mental illness in the rural community and is compared with actual number of patients with mental illness identified by the UGs. True-positive, false-positive, and true predictive values were derived.

Results In Umri village, UGs were able to identify 269 persons as true positives and 25 as false positives, whereas in Kurzadi village, UGs were able to identify 221 persons as true positives and 35 as false positives. It suggests UGs were able to identify mental illnesses with a good positive predictive value. In Umri village, out of 294 mentally ill patients, it gave a true positive value of 91.49% and a false positive value of 8.5%, whereas in Kurzadi village, out of the 256 mentally ill patients, it gave a true positive value of 86.3% and a false positive value of 13.67%.

Conclusion The ratio of psychiatrists in India is approximately 0.30 per 100,000 population due to which psychiatrists alone cannot cover the mental health problems of India. Therefore, we need a different model to cover mental illness in India, which is discussed in this article.
FEM Analysis Applied to OT Bridge Abutment with Seeger Retention System
Authors: Cervino Gabriele , Cicciù Marco , Fedi Simone , Milone Dario , Fiorillo Luca
Published: September 2020

Objective The purpose of this investigation is to highlight the technical components of a new kind of screw-retained dental implant prosthesis. The hypothesis is whether the OT Bridge (Rhein 83 S.R.L.; Bologna, Italy) system could be applied without secondary screw in the “all-on-four” retention system, thanks to the presence of an internal seeger.

Materials and Methods By using engineering device such as finite element method (FEM) and von Mises investigation, it has been studied how the fixed prosthodontics for full-arch retention can be influenced by the presence of the screw for stabilizing it.

Results In a dental implant, one model with four different configurations of the full-arch prosthesis retainer and the seeger has been investigated and then examined in contrast with or without the passant screw for locking the system. The experiments of this virtual study highlighted different features and mechanical behaviors of prosthodontic attachments.

Conclusion The first two configurations, respectively those in which there are four and three connection screws, are safe and predictable. Therefore, the presence of the seeger significantly improves the stability and the retention of the whole prosthesis.
Associação Brasileira de Nutrologia recomenda o sistema Nutri-Score como modelo de avaliação do perfil nutricional de alimentos industrializados
Authors: Nogueira-de-Almeida Carlos Alberto , Ribas-Filho Durval
Published: September 2020

Sociedades organizadas, governo e indústria têm buscado formas de garantir ao consumidor informações nutricionais confiáveis e de fácil interpretação. Um dos aspectos que se tem discutido refere-se à possibilidade de oferecer um número maior de dados, em relação a aspectos críticos à saúde, que possam decodificar, sem substituir, aqueles já presentes na lista de ingredientes e na tabela de informação nutricional, de forma a permitir rápida interpretação. Nesse sentido, a Associação Brasileira de Nutrologia está buscando colaborar com essa iniciativa propondo a utilização do modelo Nutri-Score, em forma adaptada, como um método de informação do perfil nutricional. O presente documento revisa esse modelo, demonstra sua validação científica e sugere adaptações a fim de torná-lo mais informativo.
Mycobacterium Immunogenum Flexor Tenosynovitis: A Case Report
Authors: Aryee Jomar N. A. , Akinleye Sheriff D. , Freilich Aaron M. , Deal D. Nicole
Published: September 2020

Background Nontuberculous mycobacterial (NTM) flexor tenosynovitis represents a rare but potentially devastating manifestation of upper extremity infection. We present a novel case of NTM flexor tenosynovitis in which Mycobacter iumimmunogenum was found to be the causative agent.

Case Description The patient presented with pain and insidiously progressive swelling and required multiple operative interventions and a complex antimicrobial regimen based on susceptibility profiles. Specifically, our patient was managed with three debridements and empiric antimicrobial agents based on inherent macrolide sensitivity, with later conversion to a complex antimicrobial regimen tailored to sensitivity.

Literature Review The diagnosis and management of NTM tenosynovitis arechallenging because of low suspicion, nonspecific presentation, and cumbersome laboratory identification techniques. M. immunogenum was only characterized in the past two decades, and, to our knowledge, this is the first reported case of the pathogen causing a musculoskeletal infection.

Clinical Relevance We present this case primarily because of the novelty of the organism and to demonstrate the recalcitrant nature of the infection. Due to the extensive resistant patterns of M. immunogenum, management requires complex antimicrobial preparations and almost certainly needs multispecialty collaboration between orthopaedic surgery and infectious diseases.
Anatomical Study and Clinical Application of Ulnar Artery Proximal Perforator Flaps
Authors: Cherubino Mario , Bolletta Alberto , Baroni Tommaso , Di Taranto Giuseppe , Losco Luigi , Rubino Corrado , Valdatta Luigi
Published: September 2020

Background The purpose of this study is to document the vascular anatomy of the free ulnar artery proximal perforator flap and to highlight the possibility of harvesting it based on the perforators originating from the posterior ulnar recurrent artery (PURA), to spare both the main axis of vascular supply to the hand. In addition, we present a case series of five patients treated for soft tissue defects of the hand with free ulnar artery proximal perforator flaps.

Methods Ten specimens of anterior forearm were dissected in this study to register number and characteristics of ulnar perforators. The dissection was focused on the perforators originating from the larger branch of the ulnar artery, the PURA, at the proximal third of anteromedial forearm. The anatomical dissections were evaluated in relationship with clinical dissections performed during flap harvesting in five patients.

Results In three of the specimens dissected, the proximal perforator originated from the PURA, and in the other seven specimens, it originated directly from the ulnar artery. Five cases of reconstruction of the hand were performed with success using the free ulnar artery proximal perforator flap, and in two cases, the perforator from the PURA was found and it was possible to raise the flap based on this branch of the ulnar artery.

Conclusion The free ulnar artery proximal perforator flap can be harvested in two different manners for the same skin island of the forearm. When possible, harvesting it form the PURA allows lengthening of the pedicle. In our experience, this flap presents many advantages such as thinness and hairlessness; it allows preservation of the ulnar neurovascular bundle with an acceptable donor site morbidity. Level of evidence: IV.
Microvillus Inclusion Disease: A Rare Mutation of STX3 in Exon 9 Causing Fatal Congenital Diarrheal Disease
Authors: Pournami Femitha , MK Alok Kumar , Panackal Anila V. , Nandakumar Anand , Prabhakar Jyothi , Jain Naveen
Published: September 2020

Inherited diarrheal disorders cause serious morbidity resulting in dependence on intensive care and parenteral nutrition. Microvillus inclusion disease (MVID) has been classically described and results from mutations in the gene coding myosin Vb, which is responsible for enterocyte polarization. Newer reports of mutations resulting in truncated syntaxin 3 (STX3) and Munc18-2 (STXBP2) proteins have been elucidated as causative. To date, five cases of STX3 abnormalities resulting in MVID have been described. We report an infant who presented with congenital diarrhea and was determined to have a rare mutation of STX3. This new finding would be beneficial in future functional genotype–phenotype correlation studies.
Prescribing, care and resistance: antibiotic use in urban South Africa
Authors: Manderson Lenore
Published: September 2020

In South Africa, patients’ and providers’ expectations of transactions in health services converge in consultations for acute respiratory tract infections with the prescription of antibiotics. To explore this, a qualitative study was undertaken at community health centres and private general practice surgeries in four areas of metropolitan South Africa, selected purposively to allow for wide variability in terms of socioeconomic status and ethnicities/race of patient populations. With permission, clinic waiting rooms and patient/provider consultations were observed, and 65 in-depth interviews were undertaken with patients or parents or guardians presenting with children. These interviews were complemented by interviews with health providers (26) and key informants (12). All interviews were recorded, transcribed and imported into NVivo 12 for management. Data were open coded, with individual interviews and observational data compared and contrasted to highlight understandings and practices of care, antibiotic precription and use. In this article, I illustrate how the social context of patient and provider interactions in primary care settings influenced treatment. Community health centres and clinics were (and are) stretched for resources, and there were long wait times before patients can be seen; consultations were brief, with relatively little verbal exchange on the management of coughs and colds. Providers’ decisions of treatment were informed by clinical assessment, concern about the risks of bacterial infection, and perceptions of patient ability to seek further care and advice—a mix of clinical and social considerations. While patients did not always request antibiotics and were willing to discuss how to manage acute conditions without them, doctors in private practice still often provided a prescription, sometimes post-dated to discourage use but with the option for medication if needed. In the public sector, the provision of a prescription also reflected clinicans’ appreciation of economic constraint and vulnerability. As described, patients understood principles of the appropriate use and storage of antibiotics, in contrast to other medications, and they were largely open to discussions with their providers about whether or not to use an antibiotic. However, their own and their prescribing providers had varied understandings of the mechanisms of resistance to antibiotics and so the need for antibiotic stewardship.
Discovering transition phenomena from data of stochastic dynamical systems with Lévy noise
Authors: Lu Yubin , Duan Jinqiao
Published: September 2020

It is a challenging issue to analyze complex dynamics from observed and simulated data. An advantage of extracting dynamic behaviors from data is that this approach enables the investigation of nonlinear phenomena whose mathematical models are unavailable. The purpose of this present work is to extract information about transition phenomena (e.g., mean exit time and escape probability) from data of stochastic differential equations with non-Gaussian Lévy noise. As a tool in describing dynamical systems, the Koopman semigroup transforms a nonlinear system into a linear system, but at the cost of elevating a finite dimensional problem into an infinite dimensional one. In spite of this, using the relation between the stochastic Koopman semigroup and the infinitesimal generator of a stochastic differential equation, we learn the mean exit time and escape probability from data. Specifically, we first obtain a finite dimensional approximation of the infinitesimal generator by an extended dynamic mode decomposition algorithm. Then, we identify the drift coefficient, diffusion coefficient, and anomalous diffusion coefficient for the stochastic differential equation. Finally, we compute the mean exit time and escape probability by finite difference discretization of the associated nonlocal partial differential equations. This approach is applicable in extracting transition information from data of stochastic differential equations with either (Gaussian) Brownian motion or (non-Gaussian) Lévy motion. We present one- and two-dimensional examples to demonstrate the effectiveness of our approach.
Electrical and plasma characterization of a hybrid plasma source combined with inductively coupled and capacitively coupled plasmas for O atom generation
Authors: Kim Kwan-Yong , Kim Kyung-Hyun , Moon Jun-Hyeon , Chung Chin-Wook
Published: September 2020

We developed a hybrid plasma source combined with an inductively coupled plasma (ICP) antenna and a capacitively coupled plasma (CCP) electrode. The ICP antenna and the CCP electrode are connected to a single RF power generator in parallel and a variable capacitor Cv is connected to the ICP antenna in series. The currents flowing through each source and the CCP electrode voltage are measured for analysis of the electrical characteristics, and the ion densities are measured while adjusting the capacitance of the Cv. Interestingly, when a series LC resonance occurs between the inductance of the ICP antenna and the capacitance of the Cv, different trends are observed depending on the discharge mode. In capacitive mode (E-mode), the ion density is minimized and is controlled by the CCP current. On the other hand, in inductive mode (H-mode), the ion density is maximized and is affected by the ICP current. The change of the ion density can be explained by the balance between the total power absorption and power dissipation. It is also in good qualitative agreement with the calculated plasma density from the power balance equation. By adjusting the Cv, linear control of the ion density can be achieved. To evaluate the proposed source in terms of O atom generation, the number density ratio of O atom nO to Ar nAr is obtained by using the optical emission spectroscopy actinometry method. These results show that nO/nAr is controlled. Our source can be applied to plasma processing, in which ion density and O atom generation controls are important factors.
Intrinsic recurrence quantification analysis of nonlinear and nonstationary short-term time series
Authors: Shamsan Abdulrahman , Wu Xiaodan , Liu Pengyu , Cheng Changqing
Published: September 2020

Recurrence analysis is a powerful tool to appraise the nonlinear dynamics of complex systems and delineate the inherent laminar, divergent, or transient behaviors. Oftentimes, the effectiveness of recurrence quantification hinges upon the accurate reconstruction of the state space from a univariate time series with a uniform sampling rate. Few, if any, existing approaches quantify the recurrence properties from a short-term time series, particularly those sampled at a non-uniform rate, which are fairly ubiquitous in studies of rare or extreme events. This paper presents a novel intrinsic recurrence quantification analysis to portray the recurrence behaviors in complex dynamical systems with only short-term observations. As opposed to the traditional recurrence analysis, the proposed approach represents recurrence dynamics of a short-term time series in an intrinsic state space formed by proper rotations, attained from intrinsic time-scale decomposition (ITD) of the short time series. It is shown that intrinsic recurrence quantification analysis (iRQA), patterns harnessed from the corresponding recurrence plot, captures the underlying nonlinear and nonstationary dynamics of those short time series. In addition, as ITD does not require uniform sampling of the time series, iRQA is also applicable to unevenly spaced temporal data. Our findings are corroborated in two case studies: change detection in the Lorenz time series and early-stage identification of atrial fibrillation using short-term electrocardiogram signals.
Visibility graph analysis of synthetic earthquakes generated by the Olami–Feder–Christensen spring-block model
Authors: Perez-Oregon Jennifer , Lovallo Michele , Telesca Luciano
Published: September 2020

In this study, we investigate the relationship between topological and seismological parameters of earthquake sequences generated by the Olami–Feder–Christensen (OFC) [Olami et al., Phys. Rev. Lett. 68(8), 1244 (1992)] spring-block model and converted in undirected graphs by using the visibility graph method [Lacasa et al., Proc. Natl. Acad. Sci. U.S.A. 105(13), 4972–4975 (2008)]. In particular, we study the relationship between the Gutenberg–Richter b-value and the so-called K–M slope, which describes the relationship between magnitudes and connectivity degrees. This relationship was found to follow a rather universal law in observational earthquake sequences, and, thus, in the present work, we aim at verifying such universality also in earthquake sequences generated by the OFC spring-block model. We found that for ⟨b⟩ between approximately 1 and 2, which is nearly the range of variation for most of the real seismicity cases observed worldwide, the relationship between ⟨b⟩ and ⟨K–M slope⟩ does not depend on the lattice size L. Furthermore, the slope of the regression line between ⟨b⟩ and ⟨K–M slope⟩ in the range of ⟨b⟩ between 1 and 2 changes with the definition of magnitude and the length of the earthquake sequence.
Plasma characteristics and mode transition of atmospheric pressure gas–liquid discharge oxygen plasma
Authors: Yuan Hao , Feng Jing , Yang De-Zheng , Zhou Xiong-Feng , Liang Jian-Ping , Zhang Li , Zhao Zi-Lu , Wang Wen-Chun
Published: September 2020

In this paper, a capacitor assisted AC high-voltage was employed to generate a gas–liquid discharge in pure oxygen at atmospheric pressure. The discharge images, waveforms of voltage and discharge current, and optical emission spectra of plasma were diagnosed for the purpose of investigating the discharge modes. The gas temperature (Tg), excitation temperature of hydrogen (Texc), and electron density (ne) were calculated by the spectra of OH (A2Σ–X2Π), the intensity ratio of Hα and Hβ, and the Stark broadening of Hβ, respectively. The effects of applied voltage and capacitance value on the mode transition of discharge were also discussed. It is found that due to the presence of capacitor, not only is the unlimited growth of discharge current restrained, but the transition of discharge mode is also controllable. There are three discharge modes of gas–liquid discharge oxygen plasma (GLDOP), and with the increase of applied voltage or capacitance value, discharge modes are transited from the streamer mode, to the glow-like mode, and to the abnormal glow/arc mode. With the mode transition, the Tg and Texc of GLDOP increase and the ne decreases. In contrast, the change of Tg and ne is negligible when GLDOP maintains one kind of discharge mode.
Model reduction for the collective dynamics of globally coupled oscillators: From finite networks to the thermodynamic limit
Authors: Smith Lachlan D. , Gottwald Georg A.
Published: September 2020

Model reduction techniques have been widely used to study the collective behavior of globally coupled oscillators. However, most approaches assume that there are infinitely many oscillators. Here, we propose a new ansatz, based on the collective coordinate approach, that reproduces the collective dynamics of the Kuramoto model for finite networks to high accuracy, yields the same bifurcation structure in the thermodynamic limit of infinitely many oscillators as previous approaches, and additionally captures the dynamics of the order parameter in the thermodynamic limit, including critical slowing down that results from a cascade of saddle-node bifurcations.
Monte Carlo simulation of microwave air breakdown in parallel plates considering electron-surface interaction
Authors: Mao Zhangsong , Li Yun , Ye Ming , He Yongning
Published: September 2020

In this paper, a Monte Carlo simulation method was proposed to investigate the initial cascade process of low-pressure microwave air breakdown. Calculations were performed by tracing electrons only, with the assumption that space charge was negligible. Two main electron generation mechanisms, electron-impact ionization and surface secondary electron emission (SEE), were introduced to simulate the initial breakdown phase more realistically. Detailed investigations were performed in a parallel plate waveguide operating at 9.4 GHz with pressures ranging from 0.2 Torr to 100 Torr. The results confirm that microwave breakdown is controlled by impact ionization at high pressures. However, as the gas pressure decreases, secondary electron emissions prevail against electron-neutral collisions, which leads to the sensitivity of the breakdown field on SEE. The threshold breakdown electric field obtained by the Monte Carlo method has been compared with experimental results, showing good agreement in the case where an appropriate secondary electron emission model is given. The developed Monte Carlo method provides an inexpensive way to determine the breakdown field and can be further applied to other microwave components of interest.
Synergistic effect of Coriolis and centrifugal forces from poloidal flow on internal kink and fishbone modes in tokamak plasmas
Authors: Xie Weichao
Published: September 2020

The synergy of Coriolis force and centrifugal force is proposed to study the influence of poloidal plasma rotation on internal kink and fishbone modes. A new dispersion relation is established by making use of energy principle when Coriolis and centrifugal forces are taken into account in the momentum equation. The significant discovery is that the destabilizing (stabilizing) effect of poloidal flow on internal kink (fishbone) mode is greatly increased due to the synergy of Coriolis and centrifugal forces. Poloidal flow can neither effectively destabilize internal kink mode nor stabilize fishbone mode with any one of both centrifugal force and Coriolis force being excluded. It is most interesting that the internal kink mode, being stable with positive δWc (perturbed potential energy of bulk plasma), is unstable when poloidal rotation frequency exceeds a threshold. It is difficult for poloidal flow without shear to destabilize the internal kink mode with δWc > 0. The physical mechanism of poloidal flow destabilization of internal kink mode mainly comes from the modification of plasma inertial due to Coriolis and centrifugal forces.
Investor sentiment and trading behavior
Authors: Campisi Giovanni , Muzzioli Silvia
Published: September 2020

The aim of this paper is to model trading decisions of financial investors based on a sentiment index. For this purpose, we analyze a dynamical model, which includes the sentiment index in the agents’ trading behavior. We consider the setup of a discrete dynamical system, assuming that in financial markets, transactions take place between two groups of fundamentalists that differ in their perception of fundamental value. This assumption is motivated by a degree of uncertainty about the true fundamental value. The proportion of fundamentalists in the two groups is assumed to depend on the sentiment index. The sentiment index used is related to the risk asymmetry index, enabling us to consider both the variance and the asymmetry of the prediction error between the two groups of fundamentalists. We identify the equilibria of the model and conduct a numerical analysis in order to capture stylized facts documented empirically in the financial literature.
Membrane sandwich squeeze film pressure sensors
Authors: Dantan Aurélien
Published: September 2020

Squeeze film pressure sensors exploit the dynamical modification of the mechanical properties of oscillating elements due to the compression of a fluid in a small gap region and allow for direct and absolute pressure measurements. This Tutorial article discusses the working principles of membrane sandwich squeeze film pressure sensors—i.e., sensors comprised of a parallel arrangement of two large-area, ultrathin suspended films forming a few-micrometer gap, and immersed in a fluid—and focuses on their operation in the free molecular flow regime. The effects of gas pressure on the vibrations of the membrane resonators and their coupled dynamics are discussed in general terms before recent experimental implementations using high tensile stress silicon nitride membranes are presented.
Variations on a demonic theme: Szilard’s other engines
Authors: Ray Kyle J. , Crutchfield James P.
Published: September 2020

Szilard’s now-famous single-molecule engine was only the first of three constructions he introduced in 1929 to resolve several challenges arising from Maxwell’s demon paradox. Given that it has been thoroughly analyzed, we analyze Szilard’s remaining two demon models. We show that the second one, though a markedly different implementation employing a population of distinct molecular species and semipermeable membranes, is informationally and thermodynamically equivalent to an ideal gas of the single-molecule engines. One concludes that (i) it reduces to a chaotic dynamical system—called the Szilard Map, a composite of three piecewise linear maps and associated thermodynamic transformations that implement measurement, control, and erasure; (ii) its transitory functioning as an engine that converts disorganized heat energy to work is governed by the Kolmogorov–Sinai entropy rate; (iii) the demon’s minimum necessary “intelligence” for optimal functioning is given by the engine’s statistical complexity; and (iv) its functioning saturates thermodynamic bounds and so it is a minimal, optimal implementation. We show that Szilard’s third construction is rather different and addresses the fundamental issue raised by the first two: the link between entropy production and the measurement task required to implement either of his engines. The analysis gives insight into designing and implementing novel nanoscale information engines by investigating the relationships between the demon’s memory, the nature of the “working fluid,” and the thermodynamic costs of erasure and measurement.
Effect of dust grains size distribution on the Bohm sheath criterion in plasmas
Authors: Rebiai N. , Tahraoui A. , Kechidi Z.
Published: September 2020

Taking into account the dust grain size distribution, the Bohm criterion is revisited by means of a one-dimensional, stationary, and non-magnetized theoretical model. An argon plasma is considered where the electrons are characterized by the Boltzmann distribution; however, the other species are described by the fluid equations. The dust grain charge number is described by the orbit motion limited model and their size is modeled by a Gaussian law. The generalized Bohm criterion has been calculated by using the Sagdeev's pseudo-potential approach. The numerical results show that the Bohm velocity values are greater than those of the classical model where the dust grains are absent, and they exhibit a peak. Moreover, by taking into account the dust size distribution, the obtained Bohm velocity values are practically comparable to those found in the mono-size model for a mean radius of the dust grains. Furthermore, it is found that the presence of mono-energetic electrons increases the Bohm velocity values. The dust grain surface potential at equilibrium is also calculated and discussed.
Numerical simulation of streamer evolution in surface dielectric barrier discharge with electrode-array
Authors: Zhang Jiao , Wang Yanhui , Wang Dezhen , Economou Demetre J.
Published: September 2020

Atmospheric pressure surface dielectric barrier discharges (SDBDs) may be composed of streamers fast propagating along a dielectric surface in ambient air, producing reactive oxygen and nitrogen species, and inducing a force on the neutral gas, which can find applications, respectively, in plasma medicine and aerodynamics. In this work, a two-dimensional self-consistent fluid model was developed to study SDBDs with an electrode-array. Emphasis was placed on the interaction of counter-propagating streamers and discharge uniformity for different applied voltages and geometric configurations of the electrode-array. When two counter-propagating streamers collide, the streamers come to a stop within a certain (ultimate) distance between the streamer heads. Optimizing the applied voltages is a convenient way to improve uniformity, making the streamer heads reach a minimum distance between each other. Shortening the electrode spacing can simultaneously shorten the streamer length and the ultimate distance between streamers. Under certain discharge parameters (such as applied voltage), there exists an optimum electrode spacing maximizing uniformity.
E × B electron drift current across the aperture of an ion source surrounded by a cusped magnetic field profile
Authors: Fubiani G. , Jiang Y. , Boeuf J. P.
Published: September 2020

In negative ion sources, a cusped magnetic field is generated by magnets placed around each aperture of the extraction grid in order to limit the co-extracted electron current. In spite of this suppression magnetic field, the co-extracted electron current is large, on the same order as the negative ion current extracted from the plasma. In this paper, we study the mechanisms of electron extraction from the plasma through a cusped aperture in a simplified situation, in the absence of negative ions, with the help of a three-dimensional Particle-In-Cell Monte Carlo Collisions model. The calculation results show that the electron current extracted from the plasma is small for an infinite slit aperture with a suppressed (cusped) magnetic field and significantly increases in the case of finite slit or circular grid apertures. We find that the E×B electron drift plays an important role in the extraction of electrons through a finite slit grid aperture and that current driven micro instabilities are present in the aperture region. This work is relevant to negative ion sources and micro-ECR neutralizers designed for space propulsion.
Molecular dynamics investigation of material deformation behavior of PMMA in nanoimprint lithography
Authors: Odujole Jahlani I. , Desai Salil
Published: September 2020

Computational analysis of polymeric materials plays a key role in defining their tribological characteristics. This research investigates the deformation behavior of poly(methylmethacrylate) (PMMA) as a thermoplastic resist material for the thermal nanoimprint lithography (T-NIL) process. Molecular dynamics modeling was conducted on a PMMA substrate imprinted with a rigid spherical indenter. The effect of indenter size, force, and imprinting duration on the indentation depth, penetration depth, recovery depth, and recovery percentage of the polymer was evaluated. The results showed that the largest indenter, regardless of force, had the most significant impact on deformation behavior. The 40-Å indenter with a 1 μN of force caused the surface molecules to descend to the lowest point compared to the other indenters. An increase in the indenter size resulted in a higher penetration depth, recovery depth, and recovery percentage. Higher durations of imprint cycle (400 fs) resulted in plastic deformation of the PMMA material with minimal recovery (30 Å). The results of this research lay foundation for explaining the effect of several T-NIL process parameters on the virgin PMMA thermoplastic resist material.
Experimental and modeling study of 1/f noise in multilayer MoS2 and MoSe2 field-effect transistors
Authors: Kwon Jiseok , Delker Collin J. , Thomas Harris C. , Das Suprem R. , Janes David B.
Published: September 2020

In field-effect transistors (FETs) with two-dimensional (2D) transition metal dichalcogenide channels, the dependence of field-effect mobility on atomic layer thickness has been studied and interpreted in terms of interface scattering and interlayer coupling resistance (Rint). However, a model for 1/f noise, such as in MoS2 and in MoSe2 FETs, for various contact metals and layer number thicknesses has not been reported. In this work, we have experimentally studied current–voltage and 1/f noise on MoS2 and MoSe2 FETs with source and drain contacts of high and low work function metals to understand both the mobility and the noise behavior. We have developed a noise model incorporating layer number dependent Hooge parameters and Rint. The noise and mobility models utilize screening lengths for charge, mobility, and Hooge parameter to describe the variation of these quantities with a layer number. Using our single model topology with appropriate fitting parameters for each material and each contact metal, the model captures the experimentally observed layer thickness dependence of the Hooge parameter. Our noise analysis is fully comprehensive and, hence, could be applied to any 2D layered systems.
Study of dislocations in AlN single-crystal using bright-field synchrotron x-ray topography under a multiple-beam diffraction condition
Authors: Yao Yongzhao , Tsusaka Yoshiyuki , Ishikawa Yukari , Sugawara Yoshihiro , Fujita Yu , Matsui Junji , Okada Narihito , Tadatomo Kazuyuki
Published: September 2020

Dislocations in an AlN single crystal were studied via bright-field synchrotron x-ray topography under a multiple-beam diffraction (MBD) condition. Two-beam approximation conditions using nine different types of diffraction vectors (g) were applied, including five types near the MBD condition, and the Burgers vector (b) of dislocations was identified using the g·b invisibility criterion. Based on the assignment of the Burgers vectors, some of the propagation behaviors of the dislocation were observed, including dislocation reduction via a reaction between threading edge-type dislocations and the generation of a pair of dislocations that have opposite Burgers vectors.
Transient-doped organic electrochemical transistors working in current-enhancing mode as sensing devices for low concentration of oxygen dissolved in solution
Authors: Decataldo Francesco , Gualandi Isacco , Tessarolo Marta , Scavetta Erika , Fraboni Beatrice
Published: September 2020

Dissolved oxygen in cell culture media represents an interesting parameter worth monitoring, especially at very low concentrations. Indeed, cells grow faster and live longer in hypoxic conditions, and recent studies relate stronger tumor malignancy, recurrence, and progression with reduced oxygen levels. Standard techniques for dissolved oxygen evaluation rely either on optical investigations or on electrochemical methods. The former requires complex protocols and expensive instrumentations, while for the latter, the presence of a silver/silver chloride electrode hinders the device miniaturization and induces cytotoxic effects. In this work, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (Pedot:Pss)-based Organic Electrochemical Transistors (OECTs) are presented as dissolved oxygen sensors. The catalytic activity of the Pedot chains is exploited for the transduction since oxygen reduction reactions, occurring at the polymer/electrolyte interface, induce Pedot:Pss to switch from the less conductive neutral state (off) to the more conductive oxidized one (on). This transient-doping effect enhances OECT current output, which presents a high signal to noise ratio (i.e., >102–103). The transistor architecture allows for high output/input signal power amplification (i.e., >15 dB–22 dB) and excellent sensitivities [328 ± 11 mV/dec and −0.38 ± 0.02 mA/dec for transfer and Ids(t), respectively], together with a low detection limit (0.9 µM, which represents the 0.07% of oxygen partial pressure). Finally, the here reported OECT sensors are demonstrated to work also in a real-life complex biological environment. This work paves the way for reliable, real-time oxygen monitoring in in vitro cell cultures for various relevant applications, such as investigating the influence of hypoxia conditions on cell lines or tumors.
Tilted fluctuation electron microscopy
Authors: Kennedy Ellis , Reynolds Neal , Rangel DaCosta Luis , Hellman Frances , Ophus Colin , Scott M. C.
Published: September 2020

Fluctuation electron microscopy (FEM) is a scanning nanodiffraction-based method that offers a unique approach to characterizing nanometer-scale medium-range order (MRO) in disordered materials. In addition to determining the degree of MRO, careful analysis of scanning nanodiffraction data can also be used to determine strain in thin film amorphous samples. We applied FEM to characterize the strain and MRO of magnetron sputtered amorphous tantalum (a-Ta) thin films over a range of tilt angles from 0° to 45° in order to measure any deviations between the in-plane and out-of-plane strain and MRO. We validate our approach using electron diffraction simulations of FEM experiments for a-Ta. We measure anisotropic strain in the simulated a-Ta diffraction patterns and find that the experimental a-Ta is isotropically strained within the accuracy of our method. Our approach provides a workflow for acquiring tilted scanning nanodiffraction data, determining the relative strain and ordering as a function of in- and out-of-plane directions, and removing any artifacts induced in FEM data due to strain. We also describe some limitations of the tilted FEM method when applied to thin films with very low strains.
Effect of the RF bias on the plasma density in an argon inductively coupled plasma
Authors: Lee Ho-won , Kim Kyung-Hyun , Seo Jong In , Chung Chin-Wook
Published: September 2020

Changing the RF bias is widely used to control the ion energy in inductively coupled plasma (ICP). Here, the plasma densities were measured using the floating harmonic method at various ICP powers and RF bias power frequencies. It is observed that there is an RF bias power (PB,min) that minimizes the plasma density. With increasing ICP power, PB,min is increased. When the frequency is changed from 12.5 MHz to 2 MHz, PB,min is decreased. To understand this phenomenon, the relative variation of the plasma density (δn) with the RF bias power is considered based on a power balance equation. PB,min is determined by δn, and δn changes based on the self-bias voltage caused by the RF bias power. Because the self-bias voltages change depending on the ICP power and frequency of the RF bias power, PB,min is shifted by altering the ICP power and the RF bias power frequency. The results are in good agreement with the experimental results.
Theoretical analysis for flattening of a rising bubble in a Hele–Shaw cell
Authors: Xu Xianmin , Doi Masao , Zhou Jiajia , Di Yana
Published: September 2020

We calculate the shape and the velocity of a bubble rising in an infinitely large and closed Hele–Shaw cell using Park and Homsy’s boundary condition, which accounts for the change of the three dimensional structure in the perimeter zone. We first formulate the problem in the form of a variational problem and discuss the shape change assuming that the bubble takes an elliptic shape. We calculate the shape and the velocity of the bubble as a function of the bubble size, the gap distance, and the inclination angle of the cell. We show that the bubble is flattened as it rises. This result is in agreement with experiments for large Hele–Shaw cells.
Driving force dependence of inner-sphere electron transfer for the reduction of CO2 on a gold electrode
Authors: Zhang Benjamin A. , Costentin Cyrille , Nocera Daniel G.
Published: September 2020

The kinetics of the inner-sphere electron transfer reaction between a gold electrode and CO2 was measured as a function of the applied potential in an aqueous environment. Extraction of the electron transfer rate constant requires deconvolution of the current associated with CO2 reduction from the competing hydrogen evolution reaction and mass transport. Analysis of the inner-sphere electron transfer reaction reveals a driving force dependence of the rate constant that has similar characteristics to that of a Marcus–Hush–Levich outer-sphere electron transfer model. Consideration of simple assumptions for CO2 adsorption on the electrode surface allows for the evaluation of a CO2,ads/CO2•−ads standard potential of ∼−0.75 ± 0.05 V vs Standard Hydrogen Electrode (SHE) and a reorganization energy on the order of 0.75 ± 0.10 eV. This standard potential is considerably lower than that observed for CO2 reduction on planar metal electrodes (∼>–1.4 V vs SHE for >10 mA/cm2), thus indicating that CO2 reduction occurs at a significant overpotential and thus provides an imperative for the design of better CO2 reduction electrocatalysts.