bluuebunny/crossref_metadata_2025 huggingface dataset:
Amplitude of solar gravity modes generated by penetrative plumes
Authors: Pinçon C. , Appourchaux T. , Buldgen G.
Published: March 2021

Context. The observation of gravity modes is expected to give us unprecedented insights into the inner dynamics of the Sun. Nevertheless, there is currently no consensus on their detection. Within this framework, predicting their amplitudes is essential to guide future observational strategies and seismic studies.

Aims. While previous estimates considered convective turbulent eddies as the driving mechanism, our aim is to predict the amplitude of low-frequency asymptotic gravity modes generated by penetrative convection at the top of the radiative zone.

Methods. A generation model previously developed for progressive gravity waves was adapted to the case of resonant gravity modes. The stellar oscillation equations were analyzed considering the plume ram pressure at the top of the radiative zone as the forcing term. The plume velocity field was modeled in an analytical form.

Results. We obtain an analytical expression for the mode energy. It is found to depend critically on the time evolution of the plumes inside the generation region. Using a solar model, we then compute the apparent surface radial velocity of low-degree gravity modes as would be measured by the GOLF instrument, in the frequency range 10 µHz ≤ ν ≤  100 µHz. In the case of a Gaussian plume time evolution, gravity modes turn out to be undetectable because of too small surface amplitudes. This holds true despite a wide range of values considered for the parameters of the model. In the other limiting case of an exponential time evolution, plumes are expected to drive gravity modes in a much more efficient way because of a much higher temporal coupling between the plumes and the modes than in the Gaussian case. Using reasonable values for the plume parameters based on semi-analytical models, the apparent surface velocities in this case are one order of magnitude lower than the 22-year GOLF detection threshold and lower than the previous estimates considering turbulent pressure as the driving mechanism, with a maximum value of 0.05 cm s−1 for ℓ = 1 and ν ≈ 100 µHz. When accounting for uncertainties on the plume parameters, the apparent surface velocities in the most favorable plausible case become comparable to those predicted with turbulent pressure, and the GOLF observation time required for a detection at ν ≈ 100 µHz and ℓ = 1 is reduced to about 50 yr.

Conclusions. Penetrative convection can drive gravity modes in the most favorable plausible case as efficiently as turbulent pressure, with amplitudes slightly below the current detection threshold. When detected in the future, the measurement of their amplitudes is expected to provide information on the plume dynamics at the base of the convective zone. In order to make a proper interpretation, this potential nevertheless requires further theoretical improvements in our description of penetrative plumes.
Spiral structures in gravito-turbulent gaseous disks
Authors: Béthune William , Latter Henrik , Kley Wilhelm
Published: March 2021

Context.Gravitational instabilities can drive small-scale turbulence and large-scale spiral arms in massive gaseous disks under conditions of slow radiative cooling. These motions affect the observed disk morphology, its mass accretion rate and variability, and could control the process of planet formation via dust grain concentration, processing, and collisional fragmentation.

Aims.We study gravito-turbulence and its associated spiral structure in thin gaseous disks subject to a prescribed cooling law. We characterize the morphology, coherence, and propagation of the spirals and examine when the flow deviates from viscous disk models.

Methods.We used the finite-volume code PLUTOto integrate the equations of self-gravitating hydrodynamics in three-dimensional spherical geometry. The gas was cooled over longer-than-orbital timescales to trigger the gravitational instability and sustain turbulence. We ran models for various disk masses and cooling rates.

Results.In all cases considered, the turbulent gravitational stress transports angular momentum outward at a rate compatible with viscous disk theory. The dissipation of orbital energy happens via shocks in spiral density wakes, heating the disk back to a marginally stable thermal equilibrium. These wakes drive vertical motions and contribute to mix material from the disk with its corona. They are formed and destroyed intermittently, and they nearly corotate with the gas at every radius. As a consequence, large-scale spiral arms exhibit no long-term global coherence, and energy thermalization is an essentially local process.

Conclusions.In the absence of radial substructures or tidal forcing, and provided a local cooling law, gravito-turbulence reduces to a local phenomenon in thin gaseous disks.
Localized Ventilation Method for Providing Clean Air to Hospitalized Patients
Authors: Shu Lei , Bivolarova Mariya P. , Melikov Arsen K.
Published: March 2021

Three novel air terminal devices (ATDs) for localized ventilation were designed (ATD with perforated inner plate, ATD with honeycomb diffuser, and ATD with lobbed nozzle). The ability of the ATDs to provide clean air to the breathing zone of a person lying in a hospital bed was studied. Experiments were performed in a simulated full-scale hospital patient room. A thermal manikin was used to simulate a patient. The ATD was located above the head of manikin. Heated dummy simulated a doctor standing beside the bed. Tracer gas was used to simulate contaminated air exhaled by the doctor. The supply and the exhaust flow rates were controlled at 15.3 L/s and 14.8 L/s, respectively. The supply air temperature and room temperature were kept at 23 °C and 25.3 °C, respectively. Increase of the supply air speed resulted in a cleaner air supply to the breathing zone but also increased the risk of draught. The ATD with a lobbed jet nozzle was able to reduce contaminants by more than half in the breathing zone and to provide the lowest draught risk at the face. This ATD is a better solution to supply clean air in practice comparing to the other two ATDs.
In-Use Performance of Air-to-Water Heat Pumps: are the Standards robust?
Authors: O’Donovan Adam , O’Sullivan Paul
Published: March 2021

This paper presents an energy performance comparison of air to water heat pump manufacturer quoted values, calculated seasonal performance values from standards and actual in-use values for space heating mode only. Within this, the paper determines whether an in-use factor would be suitable to correct performance predictions where differences exist. The paper also presents an in-use Carnot efficiency. Over five weeks of high-resolution data during winter and shoulder season conditions were collected and analysed for three different systems. The average in-use Carnot efficiency was found to vary largely from system to system (0.19 to 0.42). All heat pumps were found to underperform on average with respect to their standardised energy performance certificate values. The difference between standardised values and in-use values was between 11% and 53% in relative terms. The gap in performance is thought to be due to oversized or under-utilised systems. Standardised methodologies appear unable to capture potential under-performance in these types of systems. An in-use factor appeared to be an inappropriate approach in reflecting this difference. Further investigations are required to incorporate these risks into standards.
Modular split-type heat pump with compact and silent façade-integrated outdoor unit
Authors: Monteleone William , Ochs Fabian , Drexel Christof , Rothbacher Mattias
Published: March 2021

For future buildings (nZEBs according to EPBD) efficient and cost-effective heating systems with a high share of renewable energy ar0e1 r1equired. Heat pumps (HP) are considered as one of the key technologies in the building sector. However, in particular in high-density housing areas, source exploitation is strongly limited. Accordingly, the market in Austria does not currently provide real alternatives to apartment gas or electric boilers. Split type HPs with low power can be made compact and cost effective and thus offer new possibilities. However, split type HPs represent a real alternative only if the acceptance for them can be improved by means of improved modularity, design, architectural attractive integration in the building envelope and reduced sound emissions. The goal of the Austrian FFG research project FitNeS is the development and optimization of modular split HPs with compact and silent façade-integrated outdoor units. The outstanding features of the concept are a modular design with a high degree of prefabrication and representing a visually and architectonically attractive, economic and sustainable solution for both new constructions and renovations. Different concepts of façade-integrated outdoor units will be developed and evaluated with regard to design, façade construction, accessibility (for maintenance), building physics, efficiency, etc. on the basis of the technical and non-technical boundary conditions.
Seasonal storage of residential exhaust air and sewage waste heat
Authors: Hirvonen Janne , Jokisalo Juha , Kosonen Risto
Published: March 2021

Most Finnish residential buildings have been built before ventilation heat recovery options became mandatory. Exhaust air heat pumps are an effective way to reduce emissions, but they cannot cover all heating demand. Ground-source heat pumps can be designed to meet all loads, but they require corresponding amounts of space both above and below ground. This simulation study combines residential ventilation and sewage waste heat with a ground-source heat pump system to improve system sustainability and cost-effectiveness. A hybrid waste heat and ground-source heat pump system was shown to have 20% lower life cycle costs compared to a pure ground-source heat pump system. It also maintained sustainable ground temperature levels over the long term, while reducing above-ground space requirements by 95%.
Optical nanocomposites containing low refractive index MgF2 nanoparticles
Authors: Goldenberg Leonid M. , Köhler Mathias , Dreyer Christian , Krahl Tohralf , Kemnitz Erhard
Published: March 2021

Nanoparticles composed of magnesium fluoride were successfully introduced into polymer matrices used for the fabrication of planar optical waveguides. Optical layers without visible scattering were successfully prepared. The transparent nanocomposites were formulated by direct mixing of modified MgF2 nanoparticles with fluorinated co-polymer matrix or acrylate monomer mixture with a help of additional solvent. An addition of MgF2 nanoparticles results in decrease of refractive index and thermo-optic coefficient of the polymer but increases substantially the optical propagation losses for planar waveguide at 1547 nm.
Experimental investigation and fuzzy logic approach for evaluation of magnesium recovery in the reparation of Al-Mg alloys using modified stir casting method
Authors: Behera Rajesh Kumar , Samal Birajendu Prasad , Panigrahi Sarat Chandra , Behera Sanjay Kumar
Published: March 2021

Al-Mg alloys are general used for automobile and aerospace applications due to their light weight and high strength. The objective of the present investigation is an attempt to get optimum magnesium recovery during the production process. This method involves a modified stir casting method where plungers are used to feed magnesium turnings into the aluminum melt for alloy preparation. A fuzzy logic technique is used as part of the investigation for determination of Mg recovery in the alloys produced using temperature, revolution per minute (RPM) and percentage of magnesium addition as the input parameters to the fuzzy model. The results of the fuzzy model were compared with the experimental results and were found to be in good agreement. During magnesium addition process at the specific furnace maintenance temperature (FMT) and RPM, the percentage of magnesium recovery in the alloy is higher and some losses were seen due to evaporation.
A mixed integer nonlinear multiperiod model for supply chain management of a company in the retail sector
Authors: Teixeira Ana , Costa e Silva Eliana , Lopes Cristina
Published: March 2021

The fluctuations in the business environment and seasonal variations characteristic of food supply chains contribute greatly to the increasing complexity of the entire Supply Chain planning. In the present paper, quantitative models are applied to support the decision-making purchasing management department of a retail company. Specifically, a multiperiod mathematical model was developed with the aim of optimizing decision-making of the purchasing managers. The developed model consists of a multiperiod Mixed Integer Nonlinear Programming model, with the objective to minimize the ratio between how much is costing the company to move the products along the Supply Chain and the products’ costs. It is discussed how to order the product, what is the most advantageous storage mode and whether it is preferable to order once or twice a week. Real instances, provided by a Portuguese retail company, regarding the demand for one year are tested for two scenarii, which are used currently by the company. The results show that the proposed model can reduce, on both scenarios, the ratio between operational costs and merchandise costs, for almost all products, and therefore it can be an important tool for supporting decision-making of the purchasing manager.
The integrated uncapacitated lot sizing and bin packing problem
Authors: Goulart Natã , Noronha Thiago F. , Ravetti Martin G. , de Souza Mauricio C.
Published: March 2021

In the integrated uncapacitated lot sizing and bin packing problem, we have to couple lot sizing decisions of replenishment from single product suppliers with bin packing decisions in the delivery of client orders. A client order is composed of quantities of each product, and the quantities of such an order must be delivered all together no later than a given period. The quantities of an order must all be packed in the same bin, and may be delivered in advance if it is advantageous in terms of costs. We assume a large enough set of homogeneous bins available at each period. The costs involved are setup and inventory holding costs and the cost to use a bin as well. All costs are variable in the planning horizon, and the objective is to minimize the total cost incurred. We propose mixed integer linear programming formulations and a combinatorial relaxation where it is no longer necessary to keep track of the specific bin where each order is packed. An aggregate delivering capacity is computed instead. We also propose heuristics using different strategies to couple the lot sizing and the bin packing subproblems. Computational experiments on instances with different configurations showed that the proposed methods are efficient ways to obtain small optimality gaps in reduced computational times.
Business Innovation in The Hotel Industry
Authors: But Tetiana , Mamotenko Daria , Zaytseva Valentyna , Pulina Tetiana , Bukoros Tetiana
Published: March 2021

Today, business innovation is a hot topic. Therefore, it was proposed to use a competence-based approach to assess staff as a business innovation in the hotel industry. The paper investigates the theoretical and methodological principles of hotel staff evaluation using a competency-based approach. Scientific approaches are critically estimated, and aspects applied to material incentives management for hotel staff are analyzed. The scientific and theoretical basis of managing the staff’s material stimulation in the hotel business on the basis of the competency approach is investigated and practical tools of its implementation in the hotel business activities are estimated. Methodical approaches to evaluating staff competencies as a component of material incentives management have been developed. The structure of remuneration and the system of bonuses based on staff competencies evaluation have been formed, which will help increase the efficiency of personnel management in the hotel industry.
Criteria Evaluation of the Results of the Implementation of the Business Process Automation System
Authors: Holikova Kateryna , Matsyura Svitlana , Radko Viktoriia , Rudenko Nina , Zhukova Daryna
Published: March 2021

Approaches and methods of qualitative and quantitative analysis of business processes are analyzed, their advantages and disadvantages at application in an estimation of business processes of the enterprises and the organizations of various spheres of activity are defined. A method for determining the economic efficiency of the implementation of an automated design system, as well as indicators and criteria for assessing the economic efficiency of the implementation of an information system in the reengineering of business processes. The main examples of quantitative indicators are considered, in particular: process indicators, product (service) indicators and consumer and stakeholder satisfaction indicators. In the course of the research, recommendations were developed for the creation of a generalized system of indicators for assessing the business processes of enterprises and organizations, regardless of their field of activity.
Electronic (Online) Voting in Ukraine: Realities and Prospects
Authors: Lomzhets Yuliia , Dmytruk Iryna , Dubinskyi Ihor
Published: March 2021

The article considers the process of introduction of electronic voting in the electoral systems of modern countries and the condition of implementation of electronic democracy instruments in Ukraine. The main normative legal acts that have been adopted in recent years and the international experience of using the online voting system are analyzed. Prospects for further introduction of electronic voting in Ukraine, the main problems and possible ways to solve them are highlighted.
The Intellectual Component of Labor Potential as a Factor of Sustainable Development of the Agricultural Sector
Authors: Vasyl’yeva Olena , Karpenko Andrii
Published: March 2021

In the article, the proposition is substantiated that the current development of the agricultural sector is possible on condition of harmonization of environmental, social and economic factors based on the principles of consistency, balance and social justice. The paper examines the impact of the intellectual component of labor potential on economic growth in the agricultural sector. The study of the main types of production functions for macroeconomic analysis is conducted. The advantages of using the Cobb-Douglas production function in determining the levers of agricultural production growth in the context of sustainable development are substantiated. The present-day priority of activities intellectualization in the agricultural sector is proved. It is proposed to particularly focus on the use of intellectual assets of human potential for agricultural production intensification. The accomplished modeling of the agricultural sector sustainable development gives grounds for an optimistic forecast as to increasing the resource potential of agricultural production due to a growth in the quantitative and qualitative indicators of labor potential.
Women and men in orthopaedics
Authors: Errani Costantino , Tsukamoto Shinji , Kido Akira , Yoneda Azusa , Bondi Alice , Zora Frida , Soucacos Fotini , Mavrogenis Andreas F.
Published: March 2021

Purpose: To compare and discuss the gender disparities in the Orthopaedic specialty.Methods: We reviewed the literature to find the rates of women applying for an orthopaedic residency, fellowship, and academic career program, to understand the causes of the disparities in women in orthopaedics, and how this relates to orthopaedic surgical practice.Results: The idea that men and women are different and have different working styles and skills and the belief that males are more dominant and more status-worthy than females leads to gender barriers and stereotypes that restrict women from entering male-dominated specialties. It is important to mention that equivalent barriers restrict men from pursuing female-dominated specialties such as Gynecology. Economic disparities and gender stereotypes that divide medical specialties into masculine and feminine, creating a gender gap in health care are major concerns. However, the number of women in the health sector is expected to increase due to the growing amount of female students that are expected to soon graduate. A leadership gender gap also exists; although women consist of 70% of the health care workforce they occupy only 25% of leadership positions.Conclusion: The existence of gender-based disparities in healthcare is multifactorial. The explanation behind the existence of a so-called gender gap lies in organizational and individual factors. Early development and family relations, the decision between work and life balance, personal choices and interests, as well as working conditions, absence of role models and mentorship and institutional policies make gender disparities even more evident.
Leitlinienbasierter Clinical Decision Support – Anforderungen an evidenzbasierte Entscheidungsunterstützungssysteme
Authors: Börm Philipp
Published: March 2021

Hintergrund Trotz nachgewiesener Nutzen werden Systeme zur klinischen Entscheidungsunterstützung nach wie vor nicht regelmäßig im klinischen Alltag eingesetzt.

Fragestellung Der Artikel soll den theoretischen Hintergrund und die Anforderungen an leitlinienbasiertem bzw. problembasiertem Clinical Decision Support aufzeigen.

Material und Methoden Darstellung der anwendbaren mathematischen Modelle, Terminologien und weiterer theoretischer Grundlagen sowie der Probleme der bisherigen Ansätze mit Lösungsvorschlägen.

Ergebnisse und Schlussfolgerung Der Einsatz leitlinienbasierter Clinical-Decision-Support-Systeme kann zur Verbesserung von Qualität, Effizienz, Sicherheit, Transparenz und Outcomes in der klinischen Medizin beitragen.
Wie häufig sind unkomplizierte Infektionen in der ambulanten Rheumaversorgung? Ergebnisse einer Befragung von Patienten mit rheumatischen Erkrankungen
Authors: Tschirschwitz Benjamin , Keyßer Gernot
Published: March 2021

Hintergrund Patienten mit entzündlich-rheumatischen Erkrankungen haben ein erhöhtes Infektionsrisiko. Nicht nur die Erkrankung selbst, sondern auch die antirheumatische Therapie spielt dabei eine wichtige Rolle. Ziel dieser Arbeit war die Untersuchung der Häufigkeit unkomplizierter Infektionen und die Suche nach einem möglichem Underreporting derartiger Ereignisse. Geklärt werden sollte die Sichtweise der Patienten in Bezug auf das Infektionsrisiko sowie die Frage, ob unterschiedliche Therapien im klinischen Alltag messbar zu unterschiedlichen Infektionsraten führen.

Material und Methoden Zwischen 2013 und 2014 erfolgte im Raum Halle-Leipzig eine anonymisierte Patientenbefragung von 590 ambulant betreuten Patienten mit einer mindestens 2 Jahre andauernden rheumatologischen Erkrankung.

Ergebnisse Die Rate beantworteter Fragebögen betrug 78%. Daten von 432 Patienten (68% weiblich; Durchschnittsalter 55±14 Jahre) wurden ausgewertet (48% rheumatoide Arthritis). 66% der Patienten berichteten durchschnittlich 2 unkomplizierte Infektionen pro Jahr. Am häufigsten traten Atemwegsinfektionen auf (40%). 82% der Infektionen wurden ärztlich behandelt, davon jede fünfte von einem Rheumatologen. Mindestens 12% aller Infektionen wurden nicht ärztlich erfasst. Eine Biologica-Therapie erhöhte weder die Häufigkeit noch den Schweregrad von unkomplizierten Infektionen signifikant, verglichen mit konventionellen DMARDs. Die Mehrheit der Patienten unter bDMARDs sahen in dieser Therapie keine Nachteile. 58% verneinten, durch die Einnahme von Biologica häufiger unter Infektionen zu leiden. Mehr als 60% der Patienten sahen keinen Zusammenhang zwischen den Infektionen und ihrer aktuellen Medikation. Lediglich 16% der Patienten hielten eine erhöhte Infektanfälligkeit für bedenklich.

Schlussfolgerung Unkomplizierte Infektionen sind bei ambulant betreuten Rheumatikern häufig, verursachen aber offenbar wenig Probleme. Infektionen spielen im Bewusstsein der Patienten im Vergleich zu anderen unerwünschten Nebenwirkungen nicht die wichtigste Rolle. Ein vermehrtes Auftreten von unkomplizierten Infektionen unter bDMARDs konnte nicht gezeigt werden.
Vom Kollegen zum Vorgesetzten
Authors: Holtschmidt Ilona
Published: March 2021

Ein beruflicher Rollenwechsel bringt auch immer Erwartungen an die Person und deren neue Rolle mit sich. Für den Rollenträger bedeutet das nicht selten, dass er starkem Druck ausgesetzt ist. Hier ist es wichtig, die Identität in der neuen Rolle zu finden, um diese professionell auszuüben.
Familie als gesundheitserhaltende Ressource bei Spätaussiedler/innen?! Eine qualitative Studie zu Gesundheitsvorstellungen im Alter
Authors: Michalik Tanja , Koppelin Frauke , Walter Ulla
Published: March 2021

Hintergrund Im Zuge des demografischen Wandels in Deutschland steigt auch die Zahl der zweitgrößten Migrantengruppe älter werdender Spätaussiedler/innen an. Das Gesundheits- und Inanspruchnahmeverhalten präventiver Maßnahmen von Spätaussiedlerin/innen unterscheidet sich von dem der deutschen Bevölkerung oder Menschen mit einem anderen Migrationshintergrund. Eine wesentliche Voraussetzung für die Gestaltung zielgruppenspezifischer Präventionsmaßnahmen ist das Wissen über die Gesundheitsvorstellungen der Spätaussiedler/innen.

Ziel der Studie Das Ziel dieser Studie war es, die Bedeutung der Familie sowie vorherrschende Rollenbilder der Spätaussiedler/innen für die Gesundheitsvorstellungen aufzuzeigen.

Methodik Leitfadengestützte Interviews wurden mit 13 Spätaussiedler/innen in Russisch durchgeführt und mit der Dokumentarischen Methode ausgewertet.

Ergebnisse Die Familie und die Fürsorge für (Enkel-)Kinder stellt sich als zentrales Element der Gesundheitserhaltung der Befragten dar. Es zeigt sich, dass die aus der Sowjetunion mit-gebrachten traditionellen Rollenbilder z. T. erhalten bleiben, z. T. erfahren sie eine Erweiterung durch beider Geschlechter getätigte Fürsorge für die (Enkel-)Kinder.

Schlussfolgerung Für die Gesundheitserhaltung der Spätaussiedler/innen hat der Einbezug der (Enkel-)Kinder eine gesundheitsfördernde Wirkung und kann die Inanspruchnahme präventiver Maßnahmen begünstigen.
ZFAND3 Overexpression in the Mouse Liver Improves Glucose Tolerance and Hepatic Insulin Resistance
Authors: Shimizu Kahori , Ogiya Yuya , Yoshinaga Kaede , Kimura Hajime , Michinaga Shotaro , Ono Moe , Taketomi Ayako , Terada Tomoyuki , Sakurai Fuminori , Mizuguchi Hiroyuki , Tomita Koji , Nishinaka Toru
Published: March 2021

Genome-wide association studies have identified more than 300 loci associated with type 2 diabetes mellitus; however, the mechanisms underlying their role in type 2 diabetes mellitus susceptibility remain largely unknown. Zinc finger AN1-type domain 3 (ZFAND3), known as testis-expressed sequence 27, is a type 2 diabetes mellitus-susceptibility gene. Limited information is available regarding the physiological role of ZFAND3 in vivo. This study aimed to investigate the association between ZFAND3 and type 2 diabetes mellitus. ZFAND3 was significantly upregulated in the liver of diabetic mice compared to wild-type mice. To overexpress ZFAND3, we generated a ZFAND3-expressing adenovirus (Ad) vector using an improved Ad vector exhibiting significantly lower hepatotoxicity (Ad-ZFAND3). Glucose tolerance was significantly improved in Ad-ZFAND3-treated mice compared to the control Ad-treated mice. ZFAND3 overexpression in the mouse liver also improved insulin resistance. Furthermore, gluconeogenic gene expression was significantly lower in primary mouse hepatocytes transduced with Ad-ZFAND3 than those transduced with the control Ad vector. The present results suggest that ZFAND3 improves glucose tolerance by improving insulin resistance and suppressing gluconeogenesis, serving as a potential novel therapeutic target for type 2 diabetes mellitus.
Update on Phytochemical and Biological Studies on Rocaglate Derivatives from Aglaia Species
Authors: Agarwal Garima , Chang Long-Sheng , Soejarto Djaja Doel , Kinghorn A. Douglas
Published: March 2021

With about 120 species, Aglaia is one of the largest genera of the plant family Meliaceae (the mahogany plants). It is native to the tropical rainforests of the Indo-Australian region, ranging from India and Sri Lanka eastward to Polynesia and Micronesia. Various Aglaia species have been investigated since the 1960s for their phytochemical constituents and biological properties, with the cyclopenta[b]benzofurans (rocaglates or flavaglines) being of particular interest. Phytochemists, medicinal chemists, and biologists have conducted extensive research in establishing these secondary metabolites as potential lead compounds with antineoplastic and antiviral effects, among others. The varied biological properties of rocaglates can be attributed to their unusual structures and their ability to act as inhibitors of the eukaryotic translation initiation factor 4A (eIF4A), affecting protein translation. The present review provides an update on the recently
reported phytochemical constituents of Aglaia species, focusing on rocaglate derivatives. Furthermore, laboratory work performed on investigating the biological activities of these chemical constituents is also covered.
Simple optical evaluation criteria reliably identify the post-endoscopic mucosal resection scar for benign large non-pedunculated colorectal polyps without tattoo placement
Authors: Shahidi Neal , Gupta Sunil , Whitfield Anthony , Vosko Sergei , McKay Owen , Cronin Oliver , Zahid Simmi , Burgess Nicholas G. , Bourke Michael J.
Published: March 2021

Background Recognition of the post-endoscopic mucosal resection (EMR) scar is critical for large (≥ 20 mm) non-pedunculated colorectal polyp (LNPCP) management. The utility of intraluminal tattooing to facilitate scar identification is unknown.

Methods We evaluated the ability of simple easy-to-use optical evaluation criteria to detect the post-EMR scar, with or without tattoo placement, in a prospective observational cohort of LNPCPs referred for endoscopic resection. The primary outcome was scar identification, further stratified by lesion size (20–39 mm, ≥ 40 mm) and histopathology (adenomatous, serrated).

Results 1023 LNPCPs underwent both successful EMR and first surveillance colonoscopy (median size 35 mm, IQR 30–50 mm); 124 (12.1 %) had an existing tattoo or a tattoo placed at the index EMR. The post-EMR scar was identified in 1020 patients (99.7 %). The presence of a tattoo did not affect scar identification (100.0 % vs. 99.7 %; P > 0.99). There was no difference for LNPCPs 20–39 mm, LNPCPs ≥ 40 mm, adenomatous LNPCPs, and serrated LNPCPs (all P > 0.99).

Conclusions The post-EMR scar can be reliably identified with simple easy-to-use optical evaluation criteria, without the need for universal tattoo placement.
Coronavirus diffusion is aided by the shape of its spikes
Authors: Bandari Anashe
Published: March 2021

The geometry and number of spikes on a coronavirus particle affect how much the particle jitters, helping it attach to and infect its target.
Primitive model electrolytes in the near and far field: Decay lengths from DFT and simulations
Authors: Cats P. , Evans R. , Härtel A. , van Roij R.
Published: March 2021

Inspired by recent experimental observations of anomalously large decay lengths in concentrated electrolytes, we revisit the Restricted Primitive Model (RPM) for an aqueous electrolyte. We investigate the asymptotic decay lengths of the one-body ionic density profiles for the RPM in contact with a planar electrode using classical Density Functional Theory (DFT) and compare these with the decay lengths of the corresponding two-body correlation functions in bulk systems, obtained in previous Integral Equation Theory (IET) studies. Extensive Molecular Dynamics (MD) simulations are employed to complement the DFT and IET predictions. Our DFT calculations incorporate electrostatic interactions between the ions using three different (existing) approaches: one is based on the simplest mean-field treatment of Coulomb interactions (MFC), while the other two employ the Mean Spherical Approximation (MSA). The MSAc invokes only the MSA bulk direct correlation function, whereas the MSAu also incorporates the MSA bulk internal energy. Although MSAu yields profiles that are in excellent agreement with MD simulations in the near field, in the far field, we observe that the decay lengths are consistent between IET, MSAc, and MD simulations, whereas those from MFC and MSAu deviate significantly. Using DFT, we calculated the solvation force, which relates directly to surface force experiments. We find that its decay length is neither qualitatively nor quantitatively close to the large decay lengths measured in experiments and conclude that the latter cannot be accounted for by the primitive model. The anomalously large decay lengths found in surface force measurements require an explanation that lies beyond primitive models.
Raman spectroscopic study of artificially twisted and non-twisted trilayer graphene
Authors: Kim Sanghyun , Lee Donghyeon , Wang Binbin , Yu Shang-Jie , Watanabe Kenji , Taniguchi Takashi , Fan Jonathan A. , Xue Jiamin , Lee Kayoung
Published: March 2021

Twisted van der Waals systems have been receiving recent attention due to their potential for moiré-induced band modulation and corresponding exotic correlated phases. Here, we present a Raman spectroscopic study of artificial trilayer graphene (3LG), represented by monolayer graphene (1LG) on top of Bernal-stacked bilayer graphene (2LG), as a function of the twist angle (θt) with respect to each other. The artificially twisted 3LG with θt >5° shows a distinctive 2D peak, which is literally composed of the typical 2D peak of 1LG and that of 2LG, without signatures of strong coupling between the 1LG and the 2LG. The overall trends of the relative Raman shift and the full width at half maxima of the 2D peak are also provided as a function of θt ranging from 0° to 30°. In particular, non-twisted 3LG shows 2D peak characteristics very similar to those of natural Bernal-stacked 3LG, revealing that the top 1LG and the bottom 2LG are translationally rearranged to be the most thermodynamically stable state. We also realized slightly twisted 3LG with a finite θt <1°, which presents the signature of coexisting Bernal-stacked (ABA) and rhombohedral (ABC) 3LG domains.
Numerical study of vertical water entry of cylinder under the influence of wind and current
Authors: Zhou Bo , Liu Hui , Wu Zhifei , Han Xiaoshuang , Sun Tiezhi , Zhang Guiyong
Published: March 2021

Water entry is a complex nonlinear behavior that involves the multiphase flow coupling, which exists extensively in various engineering fields. In the present work, the shear stress transport k − ω turbulence model is imported to close the governing equations. The air–water interface and the six degree-of-freedom motion of the cylinder are defined using the volume of fluid method and the overlapping of grid technology, respectively. A three-dimensional numerical model to simulate the vertical water entry of cylinder under various wind and current velocities is carried out. The results generated from the unsteady dynamic characteristics of the flow field are verified against the published experimental data. A numerical parametric study is subsequently conducted to study in detail the effect of wind and current velocity on translational, rotational, and multipoint pressure characteristics in the process of water entry. The study from the evolution mechanism of cavity and the flow field revealed that the expansion speed and the closure mode of cavity change with the velocity of wind and current, which in turn affects the dynamic motion of cylinder over time and the complex distribution of pressure and velocity field and multiscale vortex structure in the process of water entry.
Deformable ferrofluid-based millirobot with high motion accuracy and high output force
Authors: Chen Dixiao , Yang Ziping , Ji Yiming , Dai Yuguo , Feng Lin , Arai Fumihito
Published: March 2021

The magnetically actuated robot has valuable potential in biomedicine, bioengineering, and biophysics for its capability to precisely manipulate particles or biological tissues. However, the deformability of rigid robots with predetermined shapes is limited, which constricts their functions and causes inconvenience for robots' movement in constricted space. In this study, we proposed a feasible and efficient ferrofluid-based robot for the transportation of tiny particles and blocks. In addition, a method to generate a patterned magnetic field is also introduced to model a ferrofluid-based robot with an adaptive shape. Benefiting from the paramagnetism and fluidity of the ferrofluid-based robot, it also demonstrates outstanding motion accuracy and output force on a superhydrophobic surface. Because of its excellent motion characteristics, high motion accuracy, and high measured output force, the proposed ferrofluid-based robot has great advantages in the field of microoperation. The correlation coefficient between the motion trajectory of the ferrofluid-based robot and the motion trajectory of the micro-stages is 0.9967. The position error is less than 1.5% of the total stroke.
A phase-field model for spall fracture
Authors: Zhang Hao , Peng Hui , Pei Xiao-yang , Li Ping , Tang Tie-gang , Cai Ling-cang
Published: March 2021

As a kind of dynamic tensile failure, the spall fracture usually happened in ductile metals under shock wave loading. Also, its macroscopic softening behavior on the stress caused by the damage is complicated due to the micro-voids nucleation, growth, and coalescence, and finally forming macro-cracks in the material. In addition, the simulated results are often mesh-dependent. Recently, the phase-field model of fracture (PFM) gains popularities in modeling fracture and damage problems. One of its advantages is that the simulated results are mesh independent. The PF-CZM by Wu [J. Mech. Phys. Solids 103, 72–99 (2017)], which is a cohesive zone model regularized by the PFM, can account for different softening behaviors via characteristic functions and proves to be suitable for spall fracture modeling. In this paper, we used the PF-CZM to conduct spall fracture modeling in consideration of constitutive description of elastic-plastic-hydrodynamics (refer to the LS-DYNA theory manual). The free surface velocity profile for plate impact experiments, including the pullback signal, pullback slope, and the first velocity peak after pullback, were simulated and well matched the experimental results. Furthermore, the results show mesh independency. Different softening behaviors were assessed for their accuracy to model the spall fracture, and parameters in this model were discussed in detail. Besides, we directly extended this model to 3D simulation, showing potential engineering applications.
Improved algorithm for the direct dynamics variational multi-configurational Gaussian method
Authors: Christopoulou Georgia , Freibert Antonia , Worth Graham A.
Published: March 2021

The Direct Dynamics variational Multi-Configurational Gaussian (DD-vMCG) method provides a fully quantum mechanical solution to the time-dependent Schrödinger equation for the time evolution of nuclei with potential surfaces calculated on-the-fly using a quantum chemistry program. Initial studies have shown its potential for flexible and accurate simulations of non-adiabatic excited-state molecular dynamics. In this paper, we present developments to the DD-vMCG algorithm that improve both its accuracy and efficiency. First, a new, efficient parallel algorithm to control the DD-vMCG database of quantum chemistry points is presented along with improvements to the Shepard interpolation scheme. Second, the use of symmetry in describing the potential surfaces is introduced along with a new phase convention in the propagation diabatization. Benchmark calculations on the allene radical cation including all degrees of freedom then show that the new scheme is able to produce a consistent non-adiabatic coupling vector field. This new DD-vMCG version thus opens the route for effectively and accurately treating complex chemical systems using quantum dynamics simulations.
Long-range spin-wave propagation in transversely magnetized nano-scaled conduits
Authors: Heinz Björn , Wang Qi , Schneider Michael , Weiß Elisabeth , Lentfert Akira , Lägel Bert , Brächer Thomas , Dubs Carsten , Dobrovolskiy Oleksandr V. , Pirro Philipp , Chumak Andrii V.
Published: March 2021

Magnonics attracts increasing attention in the view of low-energy computation technologies based on spin waves. Recently, spin-wave propagation in longitudinally magnetized nano-scaled spin-wave conduits was demonstrated, proving the fundamental feasibility of magnonics at the sub-100 nm scale. Transversely magnetized nano-conduits, which are of great interest in this regard as they offer a large group velocity and a potentially chirality-based protected transport of energy, have not yet been investigated due to their complex internal magnetic field distribution. Here, we present a study of propagating spin waves in a transversely magnetized nanoscopic yttrium iron garnet conduit of 50 nm width. Space and time-resolved microfocused Brillouin-light-scattering spectroscopy is employed to measure the spin-wave group velocity and decay length. A long-range spin-wave propagation is observed with a decay length of up to (8.0 ± 1.5) μm and a large spin-wave lifetime of up to (44.7 ± 9.1) ns. The results are supported with micromagnetic simulations, revealing a broad single-mode frequency range and the absence of a mode localized to the edges. Furthermore, a frequency nonreciprocity for counter-propagating spin waves is observed in the simulations and the experiment, caused by the trapezoidal cross section of the structure. The revealed long-distance spin-wave propagation on the nano-scale is particularly interesting for an application in spin-wave devices, allowing for long-distance transport of information in magnonic circuits and low-energy device architectures.
Betatron-type laser-plasma x-ray sources generated in multi-electron gas targets
Authors: Grigoriadis A. , Andrianaki G. , Tatarakis M. , Benis E. P. , Papadogiannis N. A.
Published: March 2021

Betatron-type laser-plasma x-rays are recorded simultaneously with their corresponding relativistic electron spectra in a laser wakefield acceleration scheme. The role of the multi-electron gas target in the betatron-type x-ray efficient generation is experimentally examined. A proof of principle experimental study shows that by using a multi-electron gas target and appropriately adjusting the pumping laser intensity an increase in betatron-type x-rays efficiency could be achieved. This is attributed to sophisticated control of the type of the electron injection inside the plasma bubble related to the tunneling ionization process occurring after the laser pulse peak. This method depends primarily on the gas target charge state chosen for attaining the ionization injection scheme and could be extended to a wide range of relativistic laser intensities.
Spin-torque switching mechanisms of perpendicular magnetic tunnel junction nanopillars
Authors: Beik Mohammadi J. , Kent A. D.
Published: March 2021

Understanding the spin-transfer magnetization switching mechanisms of perpendicular magnetic tunnel junction nanopillars is critical to optimizing their performance in memory devices. Here, we use micromagnetics to study how the free layer's exchange constant affects its switching dynamics. Switching is shown to generally occur by (1) growth of the magnetization precession amplitude in the element center; (2) an instability in which the reversing region moves to the element edge, forming magnetic domain wall(s); and (3) the motion of the domain wall(s) across the element. For small exchange and large element diameters, step 1 leads to a droplet with a fully reversed core that experiences a drift instability (step 2). While in the opposite case (large exchange and small diameters), the central region of the element is not fully reversed before step 2 occurs. The origin of the micromagnetic structure is shown to be the free layer's non-uniform demagnetization field. More coherent, energy-efficient, and faster switching is associated with larger exchange, showing that increasing the exchange interaction strength leads to improvements in device performance.
Long wavelength InAs/InAsSb superlattice barrier infrared detectors with p-type absorber quantum efficiency enhancement
Authors: Ting David Z. , Soibel Alexander , Khoshakhlagh Arezou , Keo Sam A. , Fisher Anita M. , Rafol Sir B. , Höglund Linda , Hill Cory J. , Pepper Brian J. , Gunapala Sarath D.
Published: March 2021

We studied long and very long wavelength InAs/InAsSb superlattice barrier infrared detectors that contain p-type absorber layers in order to take advantage of the longer electron diffusion length for quantum efficiency (QE) enhancement. While they can achieve higher QE than devices that use only n-type absorbers, their dark current characteristics are affected by the presence of metallurgical and surface p–n junctions, and are best operated under lower biasing conditions where the tunneling dark currents are less pronounced. Rather than using a p-type absorber only, a barrier infrared detector structure with a combination of p- and n-type absorber sections can benefit from a shallower mesa etch that reduces fabrication demands and also decreases the p-type absorber exposed surface area. We compare four complementary barrier infrared detector structures that use an n-type absorber, a combination of p- and n-type absorbers, or a p-type absorber and briefly report results from a 13.3 μm cutoff focal plane array.