bluuebunny/crossref_metadata_2025 huggingface dataset:
Scaling of a catalytic cracking fluidized bed downer reactor based on computational fluid dynamics simulations
Authors: Khongprom Parinya , Ratchasombat Supawadee , Wanchan Waritnan , Bumphenkiattikul Panut , Limtrakul Sunun
Published: January 2020

Circulating fluidized bed downer reactors (downer reactors) exhibit good heat and mass transfer, and the flow behavior approaches the ideal plug flow.
Optimized HSP90 mediated fluorescent probes for cancer-specific bioimaging
Authors: Zhu Shulei , Li Yalei , Huang Yushu , Zhang Minmin , Gu Xiaofan , He Yang , Liu Hongchun , Ma Mingliang , Lu Wei
Published: January 2020

NP-001is a promising imaging probe for detection and visualization of tumor lesions, offering low side effect and good biocompatibility.
Tunneling magnetoresistance and light modulation in Fe4N(La2/3Sr1/3MnO3)/C60/Fe4N single molecule magnetic tunnel junctions
Authors: Han Xuefei , Mi Wenbo , Wang Dunhui
Published: January 2020

Spin-dependent transport properties and light modulation of Fe4N/C60/Fe4N and LSMO/C60/Fe4N single molecule magnetic tunnel junctions.
Excitation energy dependent switchable emission in SrZnO2 nanophosphors: XAS and luminescence studies
Authors: Manju  , Jain Megha , Vashishtha Pargam , Kumar Sanjay , Rajput Parasmani , Gupta Govind , Vij Ankush , Thakur Anup
Published: January 2020

An unprecedented excitation energy dependent dual emission from SrZnO2 nanophosphors is observed, predicting its applicability for switchable light emitting devices.
Correction: Towards predicting the power conversion efficiencies of organic solar cells from donor and acceptor molecule structures
Authors: Zhou Yecheng , Long Guankui , Li Ailin , Gray-Weale Angus , Chen Yongsheng , Yan Tianying
Published: January 2020

Correction for ‘Towards predicting the power conversion efficiencies of organic solar cells from donor and acceptor molecule structures’ by Yecheng Zhou et al., J. Mater. Chem. C, 2018, 6, 3276–3287.
Detection of atherosclerosis-related hypochlorous acid produced in foam cells with a localized endoplasmic reticulum probe
Authors: Zhang Meng-meng , Ma Yin-Hua , Li Peng , Jia Yan , Han Ke-Li
Published: January 2020

We have synthesized a turn-on fluorescent probe, termed NB4OH, to detect cellular hypochlorite.
Entwicklung eines Trainingsleitfadens für Patienten mit entzündlicher Muskelerkrankung
Authors: Baschung Pfister Pierrette , Sterkele Iris , Keller Trevisan Caroline , de Bruin Eling D.
Published: January 2020

Hintergrund Inflammatorische Myopathien (IM) sind eine Gruppe seltener entzündlicher Muskelerkrankungen. Verminderte Kraft und Ausdauerfähigkeit stellen die Hauptsymptome dar. Diverse Studien konnten positive Effekte einer Trainingstherapie nachweisen, es existieren jedoch keine krankheitsspezifischen Trainingsrichtlinien.

Ziel Erstellung einer Übersicht der vorhandenen Trainingsstudien mit Fokus auf erwachsene Patienten mit IM, um daraus einen evidenzbasierten, krankheitsspezifischen Trainingsleitfaden abzuleiten.

Methode In einem ersten Schritt erfolgte eine systematische Literaturübersicht. Sie diente als Basis, um den Trainingsleitfaden zu entwickeln. Die langjährige klinische Erfahrung spezialisierter Physiotherapeuten sowie die Trainingsrichtlinien des American College of Sports Medicine fanden ebenfalls Berücksichtigung.

Ergebnisse In die systematische Übersicht wurden 24 Studien mit insgesamt 151 Patienten mit IM eingeschlossen. Alle Studien zeigten positive Effekte eines Kraft- und/oder Ausdauertrainings auf. Unerwünschte Ereignisse traten nicht ein. Der Trainingsleitfaden besteht aus einem Einführungsteil zu allgemeinen Trainingsprinzipien sowie zwei weiteren Teilen über Kraft- und Ausdauertraining für jede Krankheitsaktivität (früh-aktiv, aktiv, stabil).

Schlussfolgerungen Obwohl die Trainingsprotokolle im Bereich der Myositis unterschiedlich sind, weisen alle Studien konsistent darauf hin, dass das Training sicher und effektiv ist. Der Trainingsleitfaden ermöglicht Therapeuten einen raschen Überblick über evidenzbasierte Trainingsrichtlinien. Die Richtlinien sollten in weiteren Studien angewendet, überprüft und anschließend verfeinert werden.
Arbeitsanforderungen an Ausbilder in der praktischen Physiotherapieausbildung in Deutschland – Ergebnisse einer Interviewstudie und einer quantitativen Fragebogenerhebung
Authors: Harms Jan , Dilsner Katja
Published: January 2020

Hintergrund Die Qualität der Ausbildung korreliert maßgeblich mit der Qualifikation der Ausbilder. Die Ordnungspapiere, welche die Ausbildung regeln, beinhalten jedoch keine Qualifikationsanforderungen an die Ausbilder. Aufgaben und Anforderungen der Ausbilder, welche als Grundlage für die Formulierung von Qualifikationsanforderungen dienen können, sind bislang nicht erforscht.

Ziel Ermittlung von Anforderungen an Ausbilder, die sich aus der Ausbildertätigkeit ergeben.

Methode Leitfadengestützte Interviews mit sechs Ausbildern in Physiotherapie, Auswertung mittels inhaltlich strukturierender qualitativer Inhaltsanalyse 1. Rekonstruierte Anforderungen wurden durch einen standardisierten Fragebogen validiert (n = 102).

Ergebnisse Insgesamt wurden 36 Anforderungen identifiziert, welche die Arbeit der Ausbilder aus deren Perspektive abbilden. Nahezu alle Anforderungen weisen in der Fragebogenvalidierung Zustimmungsraten von mehr als 50 % auf. Die einzelnen Anforderungen wurden fünf übergeordneten Anforderungskategorien zugewiesen, welche den Prozess der praktischen Ausbildung chronologisch nachzeichnen.

Schlussfolgerungen Die Arbeit der Ausbilder ist komplex und vielschichtig. Vor allem in der unmittelbaren Durchführung der praktischen Ausbildung sehen sich die Ausbilder mit Anforderungen konfrontiert, deren Bewältigung insbesondere pädagogischer Kompetenzen bedürfen. Damit liegt erstmals eine empirische Beschreibung der Arbeit von Ausbildern vor, die als Diskussionsgrundlage für die Formulierung von Qualifikationsanforderungen und Konzipierung von Qualifizierungsangeboten dienen kann.
A Hammett Study of Clostridium acetobutylicum Alcohol Dehydrogenase (CaADH): An Enzyme with Remarkable Substrate Promiscuity and Utility for Organic Synthesis
Authors: Kudalkar Gaurav P. , Tiwari Virendra K. , Lee Joshua D. , Berkowitz David B.
Published: January 2020

Described is a physical organic study of the reduction of three sets of carbonyl compounds by the NADPH-dependent enzyme Clostridium acetobutylicum alcohol dehydrogenase (CaADH). Previous studies in our group have shown this enzyme to display broad substrate promiscuity, yet remarkable stereochemical fidelity, in the reduction of carbonyl compounds, including α-, β- and γ-keto esters (d-stereochemistry), as well as α,α-difluorinated-β-keto phosphonate esters (l-stereochemistry). To better mechanistically characterize this promising dehydrogenase enzyme, we report here the results of a Hammett linear free-energy relationship (LFER) study across three distinct classes of carbonyl substrates; namely aryl aldehydes, aryl β-keto esters and aryl trifluoromethyl ketones. Rates are measured by monitoring the decrease in NADPH fluorescence at 460 nm with time across a range of substrate concentrations for each member of each carbonyl compound class. The resulting v
0 versus [S] data are subjected to least-squares hyperbolic fitting to the Michaelis–Menton equation. Hammett plots of log(V
max) versus σX yield the following Hammett parameters: (i) for p-substituted aldehydes, ρ = 0.99 ± 0.10, ρ = 0.40 ± 0.09; two domains observed, (ii) for p-substituted β-keto esters ρ = 1.02 ± 0.31, and (iii) for p-substituted aryl trifluoromethyl ketones ρ = –0.97 ± 0.12. The positive sign of ρ indicated for the first two compound classes suggests that the hydride transfer from the nicotinamide cofactor is at least partially rate-limiting, whereas the negative sign of ρ for the aryl trifluoromethyl ketone class suggests that dehydration of the ketone hydrate may be rate-limiting for this compound class. Consistent with this notion, examination of the 13C NMR spectra for the set of p-substituted aryl trifluo­romethyl ketones in 2% aqueous DMSO reveals significant formation of the hydrate (gem-diol) for this compound family, with compounds bearing the more electron-withdrawing groups showing greater degrees of hydration. This work also presents the first examples of the CaADH-mediated reduction of aryl trifluoromethyl ketones, and chiral HPLC analysis indicates that the parent compound α,α,α-trifluoroacetophenone is enzymatically reduced in 99% ee and 95% yield, providing the (S)-stereoisomer, suggesting yet another compound class for which this enzyme displays high enantioselectivity.
speech understandability of repaired cleft palate patients pre and post caregiver training
Authors: jobe andrea L , d′mello Joan , Kumar Sanjay
Published: January 2020

Background: Treating speech and language problems in repaired cleft palate patients in india is still an uphill task due to lack of facilities. this study attempted to use parents as team members for the speech management of cleft palate patients in andhra pradesh, india. objectives: to investigate whether a positive change in speech understandability for individuals with cleft palate will result froma parent-administered intervention program.Materials and methods: Twenty-eight parents had enrolled for the speech camp held in september 2004. the parent-training program at the speech camp ensured that parents were given adequate awareness. out of the 28, 18 (64.28%) reported for one follow-up, referred to in this article as group i. ten (35.72%) out of the 28 came for two consecutive follow-ups, referred to in this article as group ii.Results: Pre and post training understandability scores obtained in the known context (reciting a familiar poem in the native language, counting 1 to 10) and unknown context (peer group names, family information, describing their journey from home to hospital) for group i and group ii were evaluated. results revealed that a higher percentage of cases showed significant improvement in understandability in the unknown context after treatment. unknown context can be considered a measure to assess speech understandability after training. further, it shows that parent training without practice at home may not show the desired results.Conclusion: This study reveals that parents can effect a positive change in the speech understandability of their children following training, provided the exercises are carried out regularly at home and the parents report for the follow-up assessments and guidance.
Microsurgical free tissue transfer as avaluable reconstructive procedure in foot reconstruction
Authors: el-shazly mohamed , makboul mohamed
Published: January 2020

Background: owing to the limited soft tissue donor sites in the foot area, the use of microsurgical tissue transfer is frequently becoming mandatory in this area, especially in cases of massive defects due to the common motor vehicle accidents in the territory of upper egypt. free flaps offer a great variety of available tissues to cover larger, multifocal or multistructural defects. they also improve the perfusion of the infected poorly perfused areas.Objectives: in this study, we tried to evaluate foot defects according to their size, shape and site and to determine the general and specific parameters of free tissue transfer to the foot area in concomitance with the patients needs.Materials and methods: eleven patients were included in this study. for each patient, complete history was taken, general and local examination, photographic documentation, laboratory investigations, imaging and other investigations were performed. free flap transfers were applied in all cases as follows: latissimus dorsi flap in five cases, rectus abdominis flap in three cases, scapular flap in one case, gracilis flap in one case and radial forearm flap in one case.Results: nine flaps survived. no infection or donor site complications were recorded. every patient had the optimum free flap as regards the defect size, site, depth, condition, shape, donor site availability and the recipient vessels′ condition.Conclusion: the study of the optimum free flap for foot reconstruction in relation to the defect present and patient conditions is crucial to have significant results.
Silicone Foley′s catheter: A useful splint in ear surgeries
Authors: Karanth Siddharth K. , Mokal Nitin J.
Published: January 2020

Maintenance of ear projection and post auricular sulcus in staged ear reconstruction in microtia is a trying problem. So also is the maintenance of the patency of the external auditory meatus following recanalization and meatoplasty. Numerous splints and dressing techniques have been described for the above situations. Some of the problems encountered include the availability of the materials, cost, expertise in fabrication and compliance.Aims: To devise a simple, reliable, inexpensive and readily available splint for the maintenance of post auricular sulcus and external auditory meatus opening. Settings and Design: A silicone catheter is made out of a soft and inert material that doesn′t cause tissue necrosis or any loss of skin graft. The basic design is that of a simple, self-retaining type of splint that doesn′t dislodge and can be prepared within minutes on the operating table.Materials and Methods: This splint has been used in four cases of microtia reconstruction and one case of congenital external auditory meatus stenosis between June 2006 and August 2007. A 14 or 16 Fr silicone Foley′s catheter was used. The proximal end of a catheter of required length was retained and the distal part was cut off. The catheter was looped into a circle around the base of the reconstructed ear and secured in position with a suture. A similar construct was used in cases of external auditory meatus reconstruction or recanalization. The funnel-shaped distal drainage end was sutured to the circular frame near the region of the tragus. This funnel was inserted into the external auditory canal.Results: The catheter was found to sit snugly in the newly created sulcus, thereby maintaining the sulcus and ear projection. It aided in maintaining the meatal opening of a satisfactory diameter in the case of external auditory canal recanalization. It was never found to slip or get dislodged in any of the cases. There was no skin graft loss or tissue necrosis due to the use of the splint.Conclusions: The silicone Foley′s catheter is found to be a simple, readily available, inexpensive and reliable self-retaining splint following ear elevation in microtia and external auditory meatus recanalization. The catheter is easily constructed and applied intraoperatively. The results following its usage have been uniformly good in all cases without causing any adverse events at the operated site or discomfort to the patient ensuring good compliance.
Intravenous injection of elemental mercury: A report of two cases
Authors: Gopalakrishna A. , Pavan Kumar T. V.
Published: January 2020

Two cases of intravenous injection of elemental mercury are described in this report. One patient succumbed and the other remains asymptomatic two years after the surgical removal of all the injected mercury. Management of intravenous injection of elemental mercury (intended to be an aphrodisiac in these two cases) is discussed here and the need for surgical removal of all accessible mercury has been emphasized
Measurement of Patellar Proximodistal Positioning with Limited Joint-Angle Sensitivity
Authors: Allberg Clara M. , Miles James
Published: January 2020

Objective Patellar luxation can be associated with abnormal proximodistal positioning of the patella. The current gold standard index (Insall–Salvati) for referencing this position is poorly suited to postoperative use, if the tibial tuberosity is moved surgically, but has the advantage of changing minimally with altered joint angles. The aim of this study was to identify an alternative index, which was simple to use, joint-angle insensitive and suitable for postoperative use.

Study Design Candidate indices based on the angle between stifle joint landmarks were screened across a wide range of joint angles for insensitivity to joint angle changes using vulpine and canine stifle radiographs. Intraobserver and interobserver agreements were assessed for a single candidate index using canine radiographs.

Results An angular index based on the caudal aspect of the femoral and tibial condyles and the apex of the patella was largely insensitive to joint angle variation. Intra- and interobserver agreements appeared suitable for clinical use, with low within-subject standard deviations (<1.3°) and coefficients of variations (<2.2%), and high intraclass correlation coefficients (>0.89).

Conclusion Patellar proximodistal position can be acceptably assessed at a variety of caudal joint angles using the described angular index. Further work is required to define reference intervals across a range of canine breeds.
Lower versus Standard INR Targets in Atrial Fibrillation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Authors: Pandey Arjun K. , Xu Ke , Zhang Li , Gupta Saurabh , Eikelboom John , Cook Olivia , McIntyre William F. , Lopes Renato D. , Crowther Mark , Belley-Côté Emilie P. , Whitlock Richard P.
Published: January 2020

Background Western guidelines recommend an international normalized ratio (INR) range of 2 to 3 when using warfarin for stroke prevention in atrial fibrillation (AF), but lower INR ranges are frequently used in East Asia. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) in AF patients comparing the effect of lower versus standard INR targets on thromboembolism, major bleeding, and mortality.

Methods We searched Western databases including Cochrane CENTRAL, Medline, and Embase as well as Chinese databases including SinoMed, CNKI, and Wanfang Data. We pooled risk ratios (RRs) using random-effects model. We grouped INR targets in two ways: (1) any study-specific lower versus standard targets and (2) INR ranges of approximately 1.5 to 2 versus 2 to 3.

Results Seventy-nine RCTs (n = 12,928) met eligibility criteria: 74 (n = 11,322) from East Asia and 5 (n = 1,606) from Western countries. Compared with standard targets, lower INR ranges were associated with higher rates of thromboembolism (76 RCTs, n = 12,577: 7.1% vs. 4.4%, RR 1.50, 95% confidence interval [CI] 1.29–1.74, I
2 = 0%), lower rates of major bleeding (61 RCTs, n = 10,815: 2.2% vs. 4.4%, RR 0.54, 95% CI 0.44–0.67, I
2 = 0%), and similar mortality (32 RCTs, n = 7,327: 4.8% vs. 5.2%, RR 1.00, 95% CI 0.85–1.19, I
2 = 0%). Results were similar when comparing target ranges of approximately 1.5 to 2 versus 2 to 3.

Conclusion Moderate quality evidence suggests lower INR targets reduce bleeding but increase thromboembolism in AF. The data are dominated by East-Asian studies, limiting generalizability to Western populations. Until higher quality data demonstrate otherwise, an INR range of 2 to 3 should remain standard for thromboembolic prophylaxis in AF.
Use, Perceived Usability, and Barriers to Implementation of a Patient Safety Dashboard Integrated within a Vendor EHR
Authors: Bersani Kerrin , Fuller Theresa E. , Garabedian Pamela , Espares Jenzel , Mlaver Eli , Businger Alexandra , Chang Frank , Boxer Robert B. , Schnock Kumiko O. , Rozenblum Ronen , Dykes Patricia C. , Dalal Anuj K. , Benneyan James C. , Lehmann Lisa S. , Gershanik Esteban F. , Bates David W. , Schnipper Jeffrey L.
Published: January 2020

Background Preventable adverse events continue to be a threat to hospitalized patients. Clinical decision support in the form of dashboards may improve compliance with evidence-based safety practices. However, limited research describes providers' experiences with dashboards integrated into vendor electronic health record (EHR) systems.

Objective This study was aimed to describe providers' use and perceived usability of the Patient Safety Dashboard and discuss barriers and facilitators to implementation.

Methods The Patient Safety Dashboard was implemented in a cluster-randomized stepped wedge trial on 12 units in neurology, oncology, and general medicine services over an 18-month period. Use of the Dashboard was tracked during the implementation period and analyzed in-depth for two 1-week periods to gather a detailed representation of use. Providers' perceptions of tool usability were measured using the Health Information Technology Usability Evaluation Scale (rated 1–5). Research assistants conducted field observations throughout the duration of the study to describe use and provide insight into tool adoption.

Results The Dashboard was used 70% of days the tool was available, with use varying by role, service, and time of day. On general medicine units, nurses logged in throughout the day, with many logins occurring during morning rounds, when not rounding with the care team. Prescribers logged in typically before and after morning rounds. On neurology units, physician assistants accounted for most logins, accessing the Dashboard during daily brief interdisciplinary rounding sessions. Use on oncology units was rare. Satisfaction with the tool was highest for perceived ease of use, with attendings giving the highest rating (4.23). The overall lowest rating was for quality of work life, with nurses rating the tool lowest (2.88).

Conclusion This mixed methods analysis provides insight into the use and usability of a dashboard tool integrated within a vendor EHR and can guide future improvements and more successful implementation of these types of tools.
Effects of copper doping of vanadium dioxide films on DC and terahertz conductivity
Authors: Wu Xuefei , Wu Zhiming , Mo Yajie , Ji Chunhui , Xu Xiangdong , Gou Jun , Wang Jun , Jiang Yadong
Published: January 2020

The transmission of terahertz (THz) waves in vanadium dioxide (VO2) films decreases with the decrease in resistivity caused by the insulator-to-metal transition. Doping of VO2 films with Cu leads to a narrowing of the hysteresis width and a decrease in the transition temperature. However, Cu doping affects both electrical properties and THz optical properties in such a way that for films with different doping ratios it is not possible to obtain similar resistivities and similar THz transmissions simultaneously. The investigations reported here reveal both the substitutional and interstitial roles of Cu doping, with the latter, in particular, leading to Cu separation. Further analysis shows that the conditions at grain boundaries mainly influence resistivity, while crystal quality significantly affects THz optical properties. Consequently, although the variations in resistivity and optical properties show similar trends, the ranges of variation are different. This can be attributed to the fact that, according to the Drude model, the relaxation time and static conductivity depend on the conditions at grain boundaries. The results are used to explore the possibility of balancing the electrical and THz optical performances of THz devices.
Air plasma sensor for the measurement of sound pressure using millimetric and micrometric discharges
Authors: Béquin Ph. , Nanda Tonlio A. , Durand S.
Published: January 2020

An acoustic pressure sensor is described that uses a small volume of ionized gas (microplasma) as a sensing element to estimate the sound-pressure fluctuations. This type of sensor uses electric discharge between a point and a plane to create the ionized gas useful for electroacoustic conversion. Depending on the polarity of the point (in this case negative), the applied voltage, and the distance between the electrodes (millimetric or micrometric), the electric discharge has specific operating modes and hysteretic behaviors that are described herein. The interaction of a sound wave with the volume of ionized gas causes a variation in the electric current of the microdischarge. The electroacoustic model and the expression of the sensitivity to the sound pressure, existing for the millimetric discharges (Trichel impulse regime), are briefly recalled. An empirical expression of the acoustic pressure sensitivity of millimetric and micrometric discharges is proposed. An experimental setup is developed using a waveguide. It enables the comparison of the value of the sound pressure deduced from plasma sensors to the one of a reference microphone (using a calibration method by comparison). The sensitivity to the sound pressure of these microplasma sensors is of the order of 0.4 nA/Pa.
Robust partial synchronization of delay-coupled networks
Authors: Su Libo , Wei Yanling , Michiels Wim , Steur Erik , Nijmeijer Henk
Published: January 2020

Networks of coupled systems may exhibit a form of incomplete synchronization called partial synchronization or cluster synchronization, which refers to the situation where only some, but not all, systems exhibit synchronous behavior. Moreover, due to perturbations or uncertainties in the network, exact partial synchronization in the sense that the states of the systems within each cluster become identical, cannot be achieved. Instead, an approximate synchronization may be observed, where the states of the systems within each cluster converge up to some bound, and this bound tends to zero if (the size of) the perturbations tends to zero. In order to derive sufficient conditions for this robustified notion of synchronization, which we refer to as practical partial synchronization, first, we separate the synchronization error dynamics from the network dynamics and interpret them in terms of a nonautonomous system of delay differential equations with a bounded additive perturbation. Second, by assessing the practical stability of this error system, conditions for practical partial synchronization are derived and formulated in terms of linear matrix inequalities. In addition, an explicit relation between the size of perturbation and the bound of the synchronization error is provided.
Controlling current flow in sintering: A facile method coupling flash with spark plasma sintering
Authors: Gorynski C. , Anselmi-Tamburini U. , Winterer M.
Published: January 2020

A facile method is described to couple flash sintering (FS) and spark plasma sintering (SPS). Flash spark plasma sintering (FSPS) combines advantages of both techniques: the use of pellet-shaped samples under mechanical load with the controlled passage of electric current through the sample. FSPS is realized by partially replacing graphite pressing tools (two punches and one matrix) used in standard SPS. An insulating boron nitride matrix substitutes the conducting graphite matrix to force the electric current through the sample. Additionally, external heating of the boron nitride matrix is implemented. Microstructures of standard and flash-SPS are compared using aluminum doped zinc oxide as an example. Scanning electron microscopy reveals that different microstructures are generated for SPS and FSPS. The new setups provide novel processing routes for different current sintering methods of materials under mechanical load and assist in identifying the role of the electric current or field in the microstructure.
Simulation studies of interface dynamics of secondary electron yield in perforated media
Authors: Li Yun , Ye Ming , Yang Jing , He Yongning , Cui Wanzhao , Wang Dan
Published: January 2020

The Secondary Electron Yield (SEY) is one of the key factors of multipactor, which remains a serious potential risk for high power vacuum applications. In this paper, the SEY and electron dynamics at different porous medium interfaces have been analyzed numerically for multipactor simulation and suppression. Due to the existence of an RF field, accumulated charge field, and external bias magnetic field, the previous electron trajectory tracking method in porous metal surfaces is not applicable. The real electromagnetic field distributions in porous medium, including metal and dielectric, are obtained theoretically and numerically for the calculation of electron motion. Based on the Monte Carlo simulation method, a novel numerical algorithm is proposed for the SEY calculation in porous medium. Simulation results show that SEYs of the porous dielectric perforated with cylindrical pores are correctly calculated and match well with experiments. It is demonstrated that the SEY at the porous interface is not only determined by electron motions but is also affected by the geometry structures of micro-pores. Different from the metal surface, the SEY at the porous dielectric interface increases when the width-to-depth ratio of micro-pores is greater than 1. The SEY reduces only since the depth of micro-pores is larger than lateral dimensions. As the depth gets much larger than the width, the “electron trapping” effect becomes remarkable and the SEY reduces considerably, which is promising for multipactor-free design in high power applications.
Guiding center dynamics as motion on a formal slow manifold in loop space
Authors: Burby J. W.
Published: January 2020

Since the late 1950s, the dynamics of a charged particle’s “guiding center” in a strong, inhomogeneous magnetic field have been understood in terms of near-identity coordinate transformations. The basic idea has been to approximately transform away the coupling between the fast gyration around magnetic fields lines and the remaining slow dynamics. This basic understanding now serves as a foundation for describing the kinetic theory of strongly magnetized plasmas. I present a new way to understand guiding center dynamics that does not involve complicated coordinate transformations. Starting from a dynamical system formulation of the motion of parameterized loops in a charged particle’s phase space, I identify a formal slow manifold in loop space. Dynamics on this formal slow manifold are equivalent to guiding center dynamics to all orders in perturbation theory. After demonstrating that loop space dynamics comprises an infinite-dimensional noncanonical Hamiltonian system, I recover the well-known Hamiltonian formulation of guiding center motion by restricting the (pre)symplectic structure on loop space to the finite-dimensional guiding center formal slow manifold.
On volt–ampere characteristic of symmetric CCP
Authors: Godyak Valery
Published: January 2020

The dynamic and static volt/ampere characteristics I(V) are fundamental parameters of rf discharges. The discharge volt/ampere characteristics or impedance and their scaling laws are important for verification of discharge models and in the design of rf matching-tuning networks that couple plasma with an RF power source. It is pointed out that experiments with symmetrical capacitively coupled plasmas performed in a wide range of driving frequencies, gas types and pressures, and discharge voltages demonstrate a linear static volt–ampere characteristic. Such a behavior contradicts the widely accepted rf sheath models found in textbooks. The disagreement was shown to be due to the violation of the rf sheath charge conservation and, possibly, the neglect of ionization caused by oscillating electrons in the rf sheath models.
Structure and thermal expansion of coordination shells in solid and liquid Invar alloys by molecular dynamics study
Authors: Fu Chengrui , Zhang Xingfan , Duan Yunrui , Xia Yujie , Li Tao , Dai Xinyue , Li Hui
Published: January 2020

Classical molecular dynamics simulations have been performed to study the atomic structures and thermal expansion of coordination shells in solid and liquid Invar alloys. Analysis of atomic structures reveals that there is an attraction between Fe-Ni nearest pairs, and that structural order still exists in the liquid Invar alloy. Fe—Ni bonds are found to have the smallest thermal expansion in the solid Invar alloy among three types of bonds, which plays an important role in the Invar effect. We also discover that the thermal expansion coefficient will gradually get close to the macroscopic level as the coordination shell number increases in Invar alloys. It is until the 5th coordination shell in the solid state and the 4th coordination shell in the liquid state that the thermal expansions of the coordination shells can reach the macroscale value. This study further promotes the understanding of the thermal expansions from the atomic scale.
Preplasma effects on laser ion generation from thin foil targets
Authors: Hadjisolomou P. , Tsygvintsev I. P. , Sasorov P. , Gasilov V. , Korn G. , Bulanov S. V.
Published: January 2020

Under typical experimental conditions related to the interaction of a short pulse laser with a nanometer foil target, the assumption of a target step-function number density profile ceases to be valid due to the existence of a nanosecond long amplified spontaneous emission pedestal prior to the arrival of the main pulse. As a consequence, the formation of a low density extended preplasma should be considered, making the achievement of high ion energy extremely challenging. In this work, a multiparametric study of various preplasma distributions is presented, obtained by combinations of the pedestal intensity, initial foil thickness, and main pulse intensity. Hydrodynamic simulations have been employed to find the target number density distribution prior to the arrival of the main laser pulse. The output of the hydrodynamic simulations is then combined with particle-in-cell simulations, providing a detailed understanding of the complete nanosecond-long laser-foil interaction. Once the laser pulse interacts with the preplasma, it deposits a fraction of its energy on the target, before it is either reflected from the critical density surface or transmitted through an underdense plasma channel. A fraction of hot electrons is ejected from the target, leaving the foil in a net positive potential, which in turn results in proton and heavy ion acceleration. The results of our multiparametric studies are important for forthcoming experiments on the ion acceleration with multipetawatt laser facilities.
A data-driven phase and isostable reduced modeling framework for oscillatory dynamical systems
Authors: Wilson Dan
Published: January 2020

Phase-amplitude reduction is of growing interest as a strategy for the reduction and analysis of oscillatory dynamical systems. Augmentation of the widely studied phase reduction with amplitude coordinates can be used to characterize transient behavior in directions transverse to a limit cycle to give a richer description of the dynamical behavior. Various definitions for amplitude coordinates have been suggested, but none are particularly well suited for implementation in experimental systems where output recordings are readily available but the underlying equations are typically unknown. In this work, a reduction framework is developed for inferring a phase-amplitude reduced model using only the observed model output from an arbitrarily high-dimensional system. This framework employs a proper orthogonal reduction strategy to identify important features of the transient decay of solutions to the limit cycle. These features are explicitly related to previously developed phase and isostable coordinates and used to define so-called data-driven phase and isostable coordinates that are valid in the entire basin of attraction of a limit cycle. The utility of this reduction strategy is illustrated in examples related to neural physiology and is used to implement an optimal control strategy that would otherwise be computationally intractable. The proposed data-driven phase and isostable coordinate system and associated reduced modeling framework represent a useful tool for the study of nonlinear dynamical systems in situations where the underlying dynamical equations are unknown and in particularly high-dimensional or complicated numerical systems for which standard phase-amplitude reduction techniques are not computationally feasible.
Electromagnetic field modulates aggregation propensity of amyloid peptides
Authors: Todorova N. , Bentvelzen A. , Yarovsky I.
Published: January 2020

Nonthermal effects of the electromagnetic (EM) field in the radio and microwave frequency ranges on basic biological matter are difficult to detect and thus remain poorly understood. In this work, all-atom nonequilibrium molecular dynamics simulations were performed to investigate the molecular mechanisms of an amyloidogenic peptide response to nonionizing radiation of varying field characteristics. The results showed that the EM field induced peptide conformations dependent on the field frequency and strength. At the high field strength (0.7 V/nmrms), the peptide explored a wider conformational space as the frequency increased from 1.0 to 5.0 GHz. At the intermediate strength fields (0.07–0.0385 V/nmrms), the frequencies of 1.0 and 2.5 GHz resulted in the peptide being trapped in specific conformations, with 1.0 GHz enabling both fibril-forming and fibril-inhibiting conformations, while 2.5 GHz led to formation of mostly fibril-forming conformations. In contrast, the 5.0 GHz frequency caused increased peptide dynamics and more extended conformations with fibril-enabling aromatic side-chain arrangement akin to the structures formed under ambient conditions. All the simulated frequencies at low strength fields (0.007–0.0007 V/nmrms) resulted in the formation of amyloid-prone hairpin conformations similar to those formed under the weak static electric field and ambient conditions. These results suggest that specific ranges of EM field parameters produce peptide conformations unfavorable for formation of amyloid fibrils, a phenomenon that can be exploited in treatment and prevention of amyloid diseases. Alternatively, EM field parameters can be selected to modulate the formation of well-ordered peptide assemblies as a rational design strategy for engineering biocompatible materials.
Defect engineering for high quality InP epitaxially grown on on-axis (001) Si
Authors: Shi Bei , Klamkin Jonathan
Published: January 2020

Heteroepitaxy of indium phosphide (InP) and its lattice-matched alloys on silicon (Si) show great promise for Si-based optoelectronic devices and photonic integrated circuits. Here, we report the monolithic growth of high crystalline quality InP on V-groove patterned (001) Si substrates by metalorganic chemical vapor deposition, demonstrating a low surface defect density of 4.5 × 107 cm−2, characterized by statistical electron channel contrast imaging. This advanced InP-on-Si virtual substrate is implemented by combining a compositionally graded indium gallium arsenide (InxGa1 − xAs) buffer and optimized In0.73Ga0.27As/InP strained-layer superlattices on gallium arsenide on a V-grooved Si template. These techniques gradually accommodate the lattice mismatch and effectively filter most of the generated dislocations. A comprehensive material characterization and the demonstration of room-temperature continuous-wave electrically pumped laser diodes on Si validate the suitability of using this InP-on-Si platform for monolithic integration of InP- and Si-based electronic and photonic devices.
Upper hybrid resonance heating experiments by X-mode microwaves on electron cyclotron resonance ion source
Authors: Kato Yushi , Nishiokada Takuya , Hamada Kouta , Onishi Koji , Takeda Tatsuto , Okumura Kazuki , Omori Takayuki , Kubo Wataru , Ishihara Masaki , Harisaki Shuhei
Published: January 2020

We have considered the accessibility condition of electromagnetic and electrostatic waves propagating in an electron cyclotron resonance (ECR) ion source (ECRIS) plasma and then investigated experimentally their correspondence relationships with production of multicharged ions. It has been clarified that there exists an efficient configuration of ECR zones for producing multicharged ion beams and has been suggested that a new resonance, i.e., upper hybrid resonance (UHR), must have occurred. We have been trying to perform advanced experiments with 4–6 GHz X-mode microwaves to the 2.45 GHz ECRIS plasma, and we have succeeded in enhancing the production of multicharged ions by launching X-mode microwaves of these bands. Furthermore, at the same time, we have observed sharp increases in electron energy distribution functions in the ECRIS plasma by means of probe methods. It has been concluded that the UHRs must have occurred when applying multiplex microwaves with their frequencies away from those frequencies for ECR in the ECRIS. In this paper, we will describe in brief the theoretical background and the results of these new experiments.
A memristive conservative chaotic circuit consisting of a memristor and a capacitor
Authors: Deng Yue , Li Yuxia
Published: January 2020

In this paper, a new memristor model is proposed and the corresponding emulator is presented to explore its electrical characteristics. A memristive chaotic circuit is designed based on this memristor and a capacitor, which has a conservative nature. The dynamic properties of the system, including high sensitivity to initial values and parameters, coexisting orbits, and transient phenomena, are obtained and investigated by Lyapunov exponents and phase volumes. The chaotic characteristics of the system are confirmed by circuit simulations and experimental devices, which illustrate the validity of the theoretical analyses. Furthermore, a random sequence generator is developed to explore the potential application of the circuit.
Active control of thermoacoustic instability using microsecond plasma discharge
Authors: Zhang Mingxuan , Li Jingxuan , Cheng Wenwang , Li Ting
Published: January 2020

The thermoacoustic instability produced in a simple heat-driven-acoustic-oscillation device (so-called Rijke tube) has been controlled by the periodic plasma discharge. A perforated plate is placed at the upstream of the tube as the heater. Due to the interaction between the heat and acoustic waves, thermoacoustic instabilities occur. The high-voltage microsecond pulsed plasma is generated within pin-to-pin electrodes that are used as an actuator since the pressure wave generated by the plasma is quite strong and able to attenuate the thermoacoustic sound wave in the Rijke tube. However, since the pressure waveform generated by the plasma discharge is different from the sinusoidal signal that is generated by a loudspeaker and widely used as a control actuator, it is necessary to derive the new model from the simplified Rijke tube. The time domain oscillation simulation is conducted, and the phase shift method is used to find appropriate control strategy. The discharge pressure waveform is subsequently fitted with an eighth-order Fourier series, and the overall Fourier signal is adjusted so that the first-order waveform in the discharge was similar to the analog sinusoidal control signal; the control is quite effective. It is known that when the sinusoidal control waveform of same frequency as thermoacoustic instability can meet control requirements, the non-sinusoidal signal can also control the thermoacoustic instability. Finally, according to the simulation results, the high-voltage microsecond plasma discharge is adjusted to the suitable amplitude and phase used for closed-loop control on the thermoacoustic oscillation, which significantly suppressed the instability.
Giant exchange bias effect in all-3d-metal Ni38.8Co2.9Mn37.9Ti20.4 thin film
Authors: Liu K. , Ma S. C. , Zhang Z. S. , Zhao X. W. , Yang B. , Wang D. H. , Ur Rehman S. , Zhong Z. C.
Published: January 2020

In this work, a giant exchange bias field of over 1 kOe, which is uncommon in film systems, is obtained in all-3d-metal Heusler-type Ni38.8Co2.9Mn37.9Ti20.4 thin films. The thermomagnetic curves show an unambiguous noncoincidence between zero-field-cooled and field-cooled protocols, indicating the presence of magnetically inhomogeneous phases in the film in the low temperature range. Magnetic measurements, including magnetic relaxation and magnetic memory effects, demonstrate that the exchange bias should be attributed to the exchange interaction between ferromagnetic clusters and the antiferromagnetic host in the Ni38.8Co2.9Mn37.9Ti20.4 thin film at low temperature. The local Mn-Co-Mn configuration provides the ferromagnetic contribution, which is formed in the antiferromagnetic Heusler main phase due to the small amount of Co-substitution for Ni. The achievement of the large exchange bias effect in the Ni38.8Co2.9Mn37.9Ti20.4 thin film is a significant addition to the existing multiple magneto-responsive effects in all-3d-metal Ni-Mn-based Heusler systems.
Analysis of NIF scaling using physics informed machine learning
Authors: Hsu Abigail , Cheng Baolian , Bradley Paul A.
Published: January 2020

Over 120 DT ice layer thermonuclear (TN) ignition experiments in inertial confinement fusion (ICF) were conducted on the National Ignition Facility (NIF) in the last eight years. None of the experiments achieved ignition. In fact, the measured neutron outputs from the experiments were well below what was expected. Although experiments to fine-tune the target designs are the focus of the national ICF program, insightful analysis of the existing data is a pressing need. In highly integrated ignition experiments, it is impossible to vary only one design parameter without perturbing all the other implosion variables. Thus, to determine the nonlinear relationships between the design parameters and performance from the data, a multivariate analysis based on physics models is necessary. To this end, we apply machine learning and deep learning methods to the existing NIF experimental data to uncover the patterns and physics scaling laws in TN ignition. In this study, we focus on the scaling laws between the implosion parameters and neutron yield using different supervised learning methods. Descriptions, comparisons, and contrasts between the methods are presented. Our results show that these models are able to infer a relationship between the observed stagnation conditions and neutron yields. This exploratory study will help build new capabilities to evaluate capsule designs and provide suggestions for new designs.
Development of enhanced multiwalled carbon nanotube (MWCNT) conductive polymeric nanocomposites by using acidified derivative of MWCNT as dispersant
Authors: Huang Haowei , Du Zhiqing , Huang Xiaofeng , Jiang Xiang , Zhang Xinya
Published: January 2020

The agglomeration of pristine multiwalled carbon nanotubes (MWCNTs) within a polymer matrix has largely limited the efficient conductive reinforcement of MWCNTs-based polymeric nanocomposites. In this paper, the pristine MWCNTs realized well-dispersed with the assistance of nitric acid acidified MWCNTs. The as-prepared hybrid MWCNTs were used to prepare hybrid MWCNTs buckypaper and hybrid MWCNTs/polyvinyl butyral (PVB) nanocomposites. The hybrid MWCNTs dispersion maintained good dispersing stability over 3 months. The fabrication of hybrid MWCNTs buckypaper shows that the intrinsic conductivity of the hybrid MWCNTs is 25.1 ± 0.2 S/cm, higher than the pristine ones of 23.3 ± 0.2 S/cm. The SEM images of hybrid MWCNTs/PVB nanocomposites show that hybrid MWCNTs are distributed homogenously in the PVB matrix. The conductive performance of nanocomposites is significantly enhanced with a low percolation of 0.44 ± 0.05 wt. % and a high critical exponent of 3.57.