bluuebunny/crossref_metadata_2025 huggingface dataset:
Generalised predictive current‐mode control of passive front‐end boost‐type converters
Authors: Judewicz M. G. , González S. A. , Fischer J. R. , Martínez J. F. , Carrica D. O.
Published: January 2021

In this work, an average current‐mode control strategy based on a generalised predictive control formulation for passive front‐end three‐phase boost‐type converters is proposed. A novel design procedure for the generalised predictive control strategy is introduced which considers both the cost function and disturbance model as design parameters to set the controller's dynamic response and robustness against component variations. A maximum robustness criterion was used for achieving stability up to a 70% inductance reduction with maximum possible bandwidth. The proposed strategy was compared against both a PI and a predictive deadbeat average current‐mode control using both simulations and experimental results on a converter. The generalised predictive control presented less performance variations between different operating points than the PI controller. Also, the proposed strategy is more robust than the predictive deadbeat strategy, showing a better transient response with a 50% inductance reduction and remained stable for a 71% inductance reduction, while the predictive deadbeat could not. Finally, the proposed strategy achieved a 1.4% output voltage load transient response for a load power step, and a 2.8% output voltage line transient response for a input voltage step, outperforming existing state‐of‐the‐art strategies.
Optimal and automated decentralised converter control design in more electrical aircraft power electronics embedded grids
Authors: Dewar D. , Formentini A. , Li K. , Zanchetta P. , Wheeler P.
Published: January 2021

In modern power systems, the proliferation of power electronics converters, and distributed generation raises important issues concerning inter‐connected switching units in terms of performance, stability and robustness. Such phenomenon are more prominent in micro‐grids, such as modern local low voltage distribution systems, more electric aircraft power systems etc., where many power converters are connected to the same non‐stiff low power ac grid, and strongly interact with each other. Locally designed converter control systems on the same electrical bus exhibit interactive behaviour. If not taken properly into account, external disturbances to the system at given operating conditions may result in the degradation of performance, failure to meet operating conditions and, in some cases, instability. This paper presents a new approach to synthesise converter controllers in more electric aircraft ac distribution grids (which is, however, applicable to all power electronics embedded systems), keeping in consideration dynamic interactions among subsystems. An optimal control design approach based on H2 optimisation is therefore proposed. Phase‐locked loops have also been considered, and their tuning has been included in the general tuning procedure of the whole system. Simulation, and experimental results show good improvements in terms of dynamic performance, and interaction mitigation.
Adaptive backstepping complementary sliding mode control with parameter estimation and dead‐zone modification for PMLSM servo system
Authors: Jin Hongyan , Zhao Ximei , Wang Tianhe
Published: January 2021

An adaptive backstepping complementary sliding mode control (ABCSMC) with dead‐zone parameter modification applicable to the permanent magnet linear synchronous motor is proposed in order to achieve high‐performance servo control fields. On the theoretical foundation of backstepping control and sliding mode control, a strong robust controller, ABCSMC is designed to compensate the uncertainties such as parameter variations and external disturbances occurring in the system. Additionally, an adaptive saturation function is utilized in ABCSMC to avoid the difficulty of parameter selections, so that the optimal parameters can be tuned by the adaptive laws in real time. Moreover, in order to avoid the parameter‐drift phenomenon of the adaptive laws, dead‐zone parameter modification is hereby proposed by setting a performance threshold to solve the overtraining problem. Finally, the stability of the system is proved through Lyapunov theorem and Barbalat's lemma. To investigate the capabilities of the proposed scheme, an experimental platform based on digital signal processor is implemented. The comparison results demonstrate that the proposed controller is capable of achieving higher tracking performance and stronger robustness to uncertainties with respect to parameter variations and external disturbances.
Resonant topology design method for implantable wireless power transfer system
Authors: Lin Manhao , Qiu Dongyuan , Luo Chengxin , Zhang Bo , Xiao Wenxun
Published: January 2021

The variable load and coil distance of implantable wireless power transfer system lead to unsteady output voltage, and resonant topology for wireless power transfer system is likely to solve this issue. But existing topologies are unable to meet the demands of implantable wireless power transfer system in practice. This paper presented a method to design resonant topologies for implantable wireless power transfer system in detail and proposed a series of topologies. Wireless power transfer systems based on the proposed topologies can achieve load‐independent output voltage. The output voltage is not constrained by the parameter of coils and its load‐independent feature is irrelevant to the coupling coefficient. Besides, a simple output voltage estimation method can be implemented on the transmitting side to monitor output voltage accurately. The characteristics of proposed implantable wireless power transfer systems are compared and the most attractive resonant topology named LCC/PS topology is pointed out. The proposed implantable LCC/PS wireless power transfer system has high power transfer efficiency from 60% to 76.9% at a coil distance of 5 cm when the load varies from 500 to 2500 Ω. An experimental setup is built and its working frequency is 6.78 MHz. The experimental results with acceptable tolerance show the accuracy of theoretical analysis and the excellent performance of the resonant topologies.
Dual‐mode magnetically integrated photovoltaic microconverter with adaptive mode change and global maximum power point tracking
Authors: Mashinchi Maheri Hamed , Vinnikov Dmitri , Chub Andrii , Korkh Oleksandr , Rosin Argo , Babaei Ebrahim
Published: January 2021

This study proposes a high step‐up galvanically isolated dc‐dc converter based on the quasi‐Z‐source (qZS) network. The voltage gain of the converter can change in a wide range. This feature makes the converter suitable for applications with a wide input voltage range. The range of the dc gain is increased by the implementation of the combined energy transfer principle. A reconfigurable structure is used to combine the energy transfer by the isolation transformer and the coupled inductor of the impedance‐source network. The adaptive mode change activates the energy transfer via an additional winding in the qZS network at lower voltages, which results in considerable efficiency improvement. Consequently, the input voltage range of the converter is extended to the values useful in photovoltaic applications impacted by partial shading. The proposed approach is verified in a photovoltaic (PV) microconverter, where the energy harvest from a PV module is possible during shading by enabling the global maximum power point tracking (GMPPT). It is demonstrated that the dual‐mode operation of the converter helps to achieve a flat efficiency curve along with outstanding maximum power point tracking (MPPT) performance.
Lyapunov stability of smart inverters using linearized distflow approximation
Authors: Saha Shammya Shananda , Arnold Daniel , Scaglione Anna , Schweitzer Eran , Roberts Ciaran , Peisert Sean , Johnson Nathan G.
Published: January 2021

Fast‐acting smart inverters that utilize preset operating conditions to determine real and reactive power injection/consumption can create voltage instabilities (over‐voltage, voltage oscillations and more) in an electrical distribution network if set‐points are not properly configured. In this work, linear distribution power flow equations and droop‐based Volt–Var and Volt–Watt control curves are used to analytically derive a stability criterion using Lyapunov analysis that includes the network operating condition. The methodology is generally applicable for control curves that can be represented as Lipschitz functions. The derived Lipschitz constants account for smart inverter hardware limitations for reactive power generation. A local policy is derived from the stability criterion that allows inverters to adapt their control curves by monitoring only local voltage, thus avoiding centralized control or information sharing with other inverters. The criterion is independent of the internal time‐delays of smart inverters. Simulation results for inverters with and without the proposed stabilization technique demonstrate how smart inverters can mitigate voltage oscillations locally and mitigate real and reactive power flow disturbances at the substation under multiple scenarios. The study concludes with illustrations of how the control policy can dampen oscillations caused by solar intermittency and cyberattacks.
AC optimal power flow with thermal–wind–solar–tidal systems using the symbiotic organisms search algorithm
Authors: Duman Serhat , Li Jie , Wu Lei
Published: January 2021

Optimal power flow problem is one of the most important non‐linear problems for power system planning and the operation of existing modern power networks. Recently, the incremental usage of renewable energy sources in power systems has revealed the significance of power system planning. Thus, the aim is to model the AC optimal power flow problem using thermal–wind–solar–tidal energy systems. In this study, uncertainties of wind, solar, and tidal energy systems were simulated using Weibull, Lognormal, and Gumbel probability distribution functions. Furthermore, the study presents solutions to the AC optimal power flow problem by including test cases of stochastic wind, solar, and tidal energy systems involving minimisation of cost function, active power loss, voltage deviation, enhancement of voltage stability, and contingency conditions. The solutions were tested via IEEE 30‐bus and IEEE 118‐bus test systems incorporating renewable energy sources, using different locations according to the selected thermal generating units. The symbiotic organisms search algorithm, which is one of the recently introduced optimisation algorithms, was used to solve the proposed power system planning problem, and simulation results of this algorithm were compared to the results of other algorithms such as the imperialist competitive, harmony search, backtracking search optimisation, and gravitational search algorithms.
Optimal hybrid microgrid sizing framework for the mining industry with three case studies from Australia
Authors: Ellabban Omar , Alassi Abdulrahman
Published: January 2021

The mining industry is showing increasing interest in adding renewable energy sources (RES) to their mines energy mix as one of the principles of sustainable and profitable mining. This paper proposes a systematic and integrative optimal economic hybrid microgrid sizing framework for profitability analysis in off‐grid hybrid renewable‐energy‐based microgrids in the mining industry. The proposed framework is validated with three case studies in different mining locations in Australia based on real market data, investigating various mining site power configurations, and considering the key technical, environmental, and economic considerations. The results highlight the impact of integrating RES in greenfield or brownfield mines in terms of diesel/RES assets sizing and total cost of electricity generation for each scenario, in addition to evaluating the feasibility of grid‐extension to the mining site versus on‐site generation for a greenfield scenario. Sensitivity analysis is carried out to study the impact of varying different input parameters on the system size and cost. The contributions of this research thus provide practical insights on the profitability of hybrid microgrids in mining applications to the various stakeholders such as independent power producers (IPPs), mining facility owners and policy makers.
Electromagnetic and mechanical design of module dual stator brushless doubly‐fed generator for offshore wind turbine
Authors: Wang Hao , Yu Siyang , Jin Shi , Zhang Fengge
Published: January 2021

In order to meet the higher requirements (i.e. large scale, high reliability and direct drive) of generators used for offshore wind turbine, a novel direct drive module dual stator brushless doubly‐fed generator (DSBDFG) with cage‐barrier rotor having many outstanding merits is proposed in this paper. The fundamental structure, operation principle and power flow are presented. The electromagnetic design methods of the proposed generator including power distribution of inner and outer machines, the relationship of pole number, slot number and module number, and winding design are thoroughly investigated. In order to solve the problems in structure brought by module design and reduce the weight as much as possible, a mechanical construction applied for module DSBDFG is proposed. Finally, the correctness of the proposed electromagnetic design method and the stability of the proposed mechanical construction are verified based on finite element analysis respectively.
Understanding the evolution and dust formation of carbon stars in the Large Magellanic Cloud via the JWST
Authors: Marini E. , Dell’Agli F. , Groenewegen M. A. T. , García–Hernández D. A. , Mattsson L. , Kamath D. , Ventura P. , D’Antona F. , Tailo M.
Published: January 2021

Context. Carbon stars have been, and still are, extensively studied. Given their complex internal structure and their peculiar chemical composition, they are living laboratories in which we can test stellar structure and evolution theories of evolved stars. Furthermore, they are the most relevant dust manufacturers, thus playing a crucial role in the evolution of galaxies.

Aims. We aim to study the dust mineralogy of the circumstellar envelope of carbon stars in the Large Magellanic Cloud (LMC) to achieve a better understanding of the dust formation process in the outflow of these objects. We intend to investigate the expected distribution of carbon stars in the observational planes built with the filters of the Mid-Infrared Instrument (MIRI) mounted onboard the James Webb Space Telescope (JWST) to select the best planes allowing an exhaustive characterisation of the stars.

Methods. We compared the synthetic spectral energy distributions, obtained by modelling asymptotic giant branch stars and the dust formation process in the wind, with the spectra of carbon stars in the LMC, taken with the Infrared Spectrograph onboard the Spitzer Space Telescope. From the detailed comparison between synthetic modelling and observation we characterise the individual sources and derive the detailed mineralogy of the dust in the circumstellar envelope.

Results. The sample of stars considered here is composed of stars of diverse mass, formation epoch, degree of obscuration, and metallicity. We find that precipitation of MgS on SiC seeds is common to all non-metal-poor carbon stars. Solid carbon is the dominant dust component, with percentages above 80% in all cases; a percentage between 10% and 20% of carbon dust is under the form of graphite, the remaining being amorphous carbon. Regarding the observational planes based on the MIRI filters, the colour-magnitude ([F770W]–[F1800W], [F1800W]) plane allows the best understanding of the degree of obscuration of the stars, while the ([F1800W]–[F2550W], [F1800W]) diagram allows better discrimination among stars of different metallicities.
Dynamical friction in Bose-Einstein condensed self-interacting dark matter at finite temperatures, and the Fornax dwarf spheroidal
Authors: Hartman S. T. H. , Winther H. A. , Mota D. F.
Published: January 2021

Aims. The aim of the present work is to better understand the gravitational drag forces, also referred to as dynamical friction, acting on massive objects moving through a self-interacting Bose-Einstein condensate, also known as a superfluid, at finite temperatures. This is relevant for models of dark matter consisting of light scalar particles with weak self-interactions that require nonzero temperatures, or that have been heated inside galaxies.

Methods. We derived expressions for dynamical friction using linear perturbation theory, and compared these to numerical simulations in which nonlinear effects are included. After testing the linear result, it was applied to the Fornax dwarf spheroidal galaxy, and two of its gravitationally bound globular clusters. Dwarf spheroidals are well-suited for indirectly probing properties of dark matter, and so by estimating the rate at which these globular clusters are expected to sink into their host halo due to dynamical friction, we inferred limits on the superfluid dark matter parameter space.

Results. The dynamical friction in a finite-temperature superfluid is found to behave very similarly to the zero-temperature limit, even when the thermal contributions are large. However, when a critical velocity for the superfluid flow is included, the friction force can transition from the zero-temperature value to the value in a conventional thermal fluid. Increasing the mass of the perturbing object induces a similar transition to when lowering the critical velocity. When applied to two of Fornax’s globular clusters, we find that the parameter space preferred in the literature for a zero-temperature superfluid yields decay times that are in agreement with observations. However, the present work suggests that increasing the temperature, which is expected to change the preferred parameter space, may lead to very small decay times, and therefore pose a problem for finite-temperature superfluid models of dark matter.
How dust fragmentation may be beneficial to planetary growth by pebble accretion
Authors: Drążkowska J. , Stammler S. M. , Birnstiel T.
Published: January 2021

Context. Pebble accretion is an emerging paradigm for the fast growth of planetary cores. Pebble flux and pebble sizes are the key parameters used in the pebble accretion models.

Aims. We aim to derive the pebble sizes and fluxes from state-of-the-art dust coagulation models and to understand their dependence on disk parameters and the fragmentation threshold velocity, and the impact of those on planetary growth by pebble accretion.

Methods. We used a 1D dust evolution model including dust growth and fragmentation to calculate realistic pebble sizes and mass flux. We used this information to integrate the growth of planetary embryos placed at various locations in the protoplanetary disk.

Results. Pebble flux strongly depends on disk properties including size and turbulence level, as well as the dust aggregates’ fragmentation threshold. We find that dust fragmentation may be beneficial to planetary growth in multiple ways. First of all, it prevents the solids from growing to very large sizes, at which point the efficiency of pebble accretion drops. What is more, small pebbles are depleted at a lower rate, providing a long-lasting pebble flux. As the full coagulation models are computationally expensive, we provide a simple method of estimating pebble sizes and flux in any protoplanetary disk model without substructure and with any fragmentation threshold velocity.
Research on steering control performance of electric forklift with steer by wire
Authors: Feng Chuan
Published: January 2021

Forklift plays an important role in cargo handling in the warehouse; therefore, it is necessary to ensure the stability of the forklift when turning to guarantee the safety of transportation. In this study, the particle swarm optimization (PSO) algorithm was improved by a genetic algorithm (GA), and the parameters of the proportion, integration, and differentiation (PID) controller were calculated using the improved algorithm for forklift steering control. Then simulation experiments were carried out using MATLAB. The results showed that the convergence speed of the improved PSO algorithm was faster than that of GA, and its adaptive value after convergence stability was significantly lower than that of the PSO algorithm; whether it was low-speed or high-speed steering, the three algorithms responded to the steering signal quickly; the yaw velocity and sideslip angle of the forklift steering under the improved PSO algorithm were more suitable for stable steering, and the increase of the steering speed would increase the yaw velocity. The novelty of this paper is that the traditional PSO algorithm is improved by GA and the particle swarm jumps out of the locally optimal solution through the crossover and mutation operations.
Improvement of the traffic safety system
Authors: Shubenkova Ksenia , Boyko Aleksey , Yakupova Gulnara , Magdin Kirill
Published: January 2021

Increase of the road safety is the main goal in the sphere of transport management. Authors state that the decision-making process should be based on the analysis of statistical data on the violations, traffic reasons of accidents and problem areas. Official statistics of the State Traffic Safety Inspectorate is used as an initial information. As a method to determine factors influencing the traffic safety, the so-called Haddon matrix was used. Efficiency of the proposed recommendations is analyzed from the viewpoint of their role in the process of ensuring safety and sustainability of the city transport system.
Development of on-board Diagnostic Systems for Vehicles to Improve their Reliability
Authors: Kulakov Aleksandr , Muhametdinov Eduard , Tsybunov Eduard , Badriev Ayrat
Published: January 2021

The article is dedicated to various questions of control and diagnostics of automobile technical conditions by applying on-board diagnostic system. The structure of automated diagnostic system was analyzed. Various types of sensors, signals and required types of their transfigurations were enlisted . The relationship between the structural and diagnostic parameters of the car is given, where all systems and car units are divided into groups. The first group consists of systems, units and machine parts that provide traffic safety, the second group contains the remaining functional systems. A structural and investigation scheme for diagnosing automobile’s brake gear with an air pressure brake system was developed.
Ways of Solving of Safety Problems of Single-Track Vehicles
Authors: Gaevskiy Vitaly , Odinokova Irina
Published: January 2021

This article describes the ways of solving essential problems regarding the safety of single-track vehicles (STV). All test procedures and STV research works were developed and approved by the authors.
Improving the Supply System Gas Engine to Improve Energy Efficiency
Authors: Khakimov Ramil , Didmanidze Otari , Parlyuk Ekaterina
Published: January 2021

The paper presents the main advantages and disadvantages of standard fuels in comparison with alternative fuels of methane series used in internal combustion engines. Particular attention in the article is given to the study of the heat transfer parameters of the calculated volume in the fuel tank filled with liquefied methane with thermal insulation, as well as methane outflow in special round tubes to transport gas in the liquid phase to the atomizer of the gas injector. Variants of numerical modeling of phase transitions of the heterogeneous system inside the tank are presented, as the calculated volume and flow of a two-phase flow of liquefied methane in tubes in the horizontal plane, taking into account the operating parameters of the elements of the fuel supply system.
The Diagnosing of Vehicle Steering System by Video Recording Method
Authors: Smolenkov Fedor , Blyankinshtein Igor
Published: January 2021

The possibility of vehicle steering system diagnosis based on analysis and visualization data processing is considered. The video recording method for the diagnostic troubleshooting of steering system and front suspension group is proposed. The method provides for placement of the motor vehicle on the diagnostic station, with further webcamera installation for measuring the steering wheel rotation angle and clear contract marking on the steering joint under experiment, setting the webcamera to fix and record the beginning of the movement steering joint under experiment, the video registration of the steering test results and further video processing using dedicated software. The outcomes of the evaluation of the method is delivered.
The Irregularity Change of the Technical State`s Elements of the Vehicle: form Submission
Authors: Novikov Alexander , Grebennikov Sergey , Grebennikov Alexander
Published: January 2021

Analyzed the use of the term «irregularity changes of technical condition of element’s vehicle» to certain stages of the operational cycle. Specific examples and quantitative assessment of irregularity changes the structural parameters for the elements, working independently, and interacting in the units or systems of the vehicle.
Modern Educational Technology in Teaching of Transport Field
Authors: Konovalova Tatyana , Maluka Lyudmila , Kiriy Consuella , Zarovnaya Larisa
Published: January 2021

Technical universities that carry out educational activities in the field of transport training and specialization have accumulated rich experience of modern teaching technologies. The final result of specific competence developing can be achieved only on the basis of a number of intermediate results in the learning of several disciplines through the implementation of multi-disciplinary projects. Multi - disciplinary projects implementation allows to develop the graduate qualification work more efficiently and in a short term. Of great importance in preparation of graduates in the field of transport specialization are the connection of education, science and operation. Creation of a practice-oriented educational process ensures the efficiency and attraction of the education for the all involved participants.
Global Problems of Development of the Agglomeration Transport Systems
Authors: Bludyan Norair
Published: January 2021

The article describes the trends of development of the agglomeration transport systems and scientific and methodological problems of territorial-transport forecasting and planning. Native and international experience in the use of “large amounts of data” in the organization of passenger transport was considered. Promising areas of agglomeration transport systems were determined.
The Definition of the Parameters of Innovative Transport and Technological Equipment for the In-Road Pavement Recycling, Using the Method of The Analysis of Fourth Coordinate of The Process
Authors: Seliverstov Nikolai , Kustarev Gennadiy , Mandrovskiy Konstantin , Izmailova Dilyara , Glagoleva Svetlana
Published: January 2021

The features of the workflow of innovative transport and technological machines with non-waste technology, multi-purpose machines, recyclers and others similar are described in the article. The calculation methodology for determining the optimal parameters of machines and modes of operation, based on method of the analysis of fourth coordinate (duration) of the operating cycle, is presented. Dependences for determination of the power drive units of recycler are given. The procedure allows optimizing the parameters of the individual equipment units and of the entire recycler machine is described.
Pulsating minimum quantity lubrication assisted high speed turning on bio-medical Ti-6Al-4V ELI Alloy: An experimental investigation
Authors: Kumar Ramanuj , Sahoo Ashok Kumar
Published: January 2021

Machining of bio-medical Ti-6Al-4V ELI grade is categorized in difficult to cut metal alloys due to its lower thermal conductivity and highly reactive in nature at elevated temperature. However, to improve the machinability of this alloy, controlling the temperature during cutting action is a challenging task. On this context, current work introduced a novel cooling strategy named as pulsating minimum quantity lubrication technique to investigate the surface roughness, surface texture (surface topology, surface profile, amplitude distribution curve, Bearing area curve, and Power spectrum), tool-work temperature, and flank wear in high-speed CNC turning of Ti-6Al-4V ELI Alloy. Feed is the leading influencing term towards surface roughness, pulse time contributing the highest impact towards tool-work temperature while flank wear is largely influenced by cutting speed. Abrasion, notch wear, adhesion and diffusion mode of wear is found.
Catalytic Hydrogen Isotope Exchange Reactions in Late-Stage Functionalization
Authors: Shi Hang , Kang Qi-Kai
Published: January 2021

The introduction of deuterium and tritium into molecules is of great importance in drug discovery. Many attempts have been made to develop late-stage hydrogen isotope exchange (HIE) reactions to avoid multistep syntheses using commercially available labeled precursors. In this review, we summarize recent progress in catalytic HIE reactions, with our main focus on their applications in the late-stage labeling of bioactive complex molecules and pharmaceuticals1 Introduction

2 Non-Transition-Metal-Catalyzed Hydrogen Isotope Exchange

2.1 Organocatalysis

2.2 Photoredox Catalysis

3 Transition-Metal-Catalyzed Hydrogen Isotope Exchang

3.1 Palladium

3.2 Ruthenium

3.3 Iridium

3.4 Other Metals

4 Summary
Specific Point-of-Care Testing of Coagulation in Patients Treated with Dabigatran
Authors: Härtig Florian , Birschmann Ingvild , Peter Andreas , Ebner Matthias , Spencer Charlotte , Gramlich Michael , Richter Hardy , Kuhn Joachim , Lehmann Rainer , Blumenstock Gunnar , Zuern Christine S. , Ziemann Ulf , Poli Sven
Published: January 2021

Background and Purpose Accurate and rapid assessment of coagulation status is necessary to guide thrombolysis or reversal of anticoagulation in stroke patients, but commercially available point-of-care (POC) assays are not suited for coagulation testing in patients treated with direct oral anticoagulants (DOACs). We aimed to evaluate the direct thrombin monitoring (DTM) test card by Helena Laboratories (Texas, United States) for anti-IIa-specific POC coagulation testing, hypothesizing that its POC-ecarin clotting time (POC-ECT) accurately reflects dabigatran plasma concentrations.

Methods A prospective single-center diagnostic study (ClinicalTrials.gov-identifier: NCT02825394) was conducted enrolling patients receiving a first dose of dabigatran and patients already on dabigatran treatment. Blood samples were collected before drug intake and 0.5, 1, 2, 8, and 12 hours after intake. POC-ECT was performed using whole blood (WB), citrated blood (CB), and citrated plasma (CP). Dabigatran plasma concentrations were determined by mass spectrometry.

Results In total, 240 blood samples from 40 patients contained 0 to 275 ng/mL of dabigatran. POC-ECT with WB/CB/CP ranged from 20 to 186/184/316 seconds. Pearson's correlation coefficient showed a strong correlation between dabigatran concentrations and POC-ECT with WB/CB/CP (R2
 = 0.78/0.90/0.92). Dabigatran concentrations >30 and >50 ng/mL (thresholds for thrombolysis, surgery, and reversal therapy according to clinical guidelines) were detected by POC-ECT with WB/CB/CP (>36/35/45 and >43/45/59 seconds) with 95/97/97 and 96/98/97% sensitivity, and 81/87/94 and 74/60/91% specificity.

Conclusion This first study evaluating DOAC-specific POC coagulation testing revealed an excellent correlation of POC-ECT with actual dabigatran concentrations. Detecting clinically relevant dabigatran levels with high sensitivity/specificity, the DTM assay represents a suitable diagnostic tool in acute stroke, hemorrhage, and urgent surgery.
Endothelial Dysfunction, Atherosclerosis, and Increase of von Willebrand Factor and Factor VIII: A Randomized Controlled Trial in Swine
Authors: Atiq Ferdows , van de Wouw Jens , Sorop Oana , Heinonen Ilkka , de Maat Moniek P. M. , Merkus Daphne , Duncker Dirk J. , Leebeek Frank W. G.
Published: January 2021

It is well known that high von Willebrand factor (VWF) and factor VIII (FVIII) levels are associated with an increased risk of cardiovascular disease. It is still debated whether VWF and FVIII are biomarkers of endothelial dysfunction and atherosclerosis or whether they have a direct causative role. Therefore, we aimed to unravel the pathophysiological pathways of increased VWF and FVIII levels associated with cardiovascular risk factors. First, we performed a randomized controlled trial in 34 Göttingen miniswine. Diabetes mellitus (DM) was induced with streptozotocin and hypercholesterolemia (HC) via a high-fat diet in 18 swine (DM + HC), while 16 healthy swine served as controls. After 5 months of follow-up, FVIII activity (FVIII:C) was significantly higher in DM + HC swine (5.85 IU/mL [5.00–6.81]) compared with controls (4.57 [3.76–5.40], p = 0.010), whereas VWF antigen (VWF:Ag) was similar (respectively 0.34 IU/mL [0.28–0.39] vs. 0.34 [0.31–0.38], p = 0.644). DM + HC swine had no endothelial dysfunction or atherosclerosis during this short-term follow-up. Subsequently, we performed a long-term (15 months) longitudinal cohort study in 10 Landrace–Yorkshire swine, in five of which HC and in five combined DM + HC were induced. VWF:Ag was higher at 15 months compared with 9 months in HC (0.37 [0.32–0.42] vs. 0.27 [0.23–0.40], p = 0.042) and DM + HC (0.33 [0.32–0.37] vs. 0.25 [0.24–0.33], p = 0.042). Both long-term groups had endothelial dysfunction compared with controls and atherosclerosis after 15 months. In conclusion, short-term hyperglycemia and dyslipidemia increase FVIII, independent of VWF. Long-term DM and HC increase VWF via endothelial dysfunction and atherosclerosis. Therefore, VWF seems to be a biomarker for advanced cardiovascular disease.
Quantitative examination of early diabetes by light-emitting diodes light-induced pupillary light reflex
Authors: Yan Y. J. , Tsai Y. C. , Ko M. L. , Lee N. C. , Chiou J. C. , Ou-Yang M.
Published: January 2021

This study investigated the abnormal pupillary light reflex in patients with early diabetes mellitus (DM) without retinopathy by using a custom-made noninvasive portable pupilometer. The pupilometer recorded and analyzed the pupillary light reflex. Two light intensities, 0.2 cd and 1.2 cd, and four wavelengths of stimulus light—white (400 nm–800 nm), red (640 ± 5 nm), green (534 ± 5 nm), and blue (470 ± 5 nm)—were used to stimulate the pupil for 10 ms. The pupillary response was recorded for 15 s. A total of 40 healthy people and 40 people with DM without retinopathy participated in the experiment at the National Taiwan University Hospital. The mean and standard deviation of DM duration were 4.5 years and 3.9 years. Of the 16 indices, the duration that pupil restores from its minimum size to half of its resting size (DRP), maximum pupil restoration velocity (MRV), and average restoration velocity (ARV) exhibited the most significant differences between the healthy people and those with DM. Compared with healthy participants, DRP was 16.33% higher, and MRV and ARV were 17.45% and 4.58% lower, respectively, in those with DM. This might be attributable to the sympathetic nervous system (SNS) controlling the dilator muscle during the dark-adapted period and relaxing the pupil; the SNS had few degenerated nerve endings in people with DM. The three aforementioned indices might be used to evaluate the severity of autonomic neuropathy in early DM.
Transients generate memory and break hyperbolicity in stochastic enzymatic networks
Authors: Kumar Ashutosh , Adhikari R. , Dua Arti
Published: January 2021

The hyperbolic dependence of catalytic rate on substrate concentration is a classical result in enzyme kinetics, quantified by the celebrated Michaelis–Menten equation. The ubiquity of this relation in diverse chemical and biological contexts has recently been rationalized by a graph-theoretic analysis of deterministic reaction networks. Experiments, however, have revealed that “molecular noise”—intrinsic stochasticity at the molecular scale—leads to significant deviations from classical results and to unexpected effects like “molecular memory,” i.e., the breakdown of statistical independence between turnover events. Here, we show, through a new method of analysis, that memory and non-hyperbolicity have a common source in an initial, and observably long, transient peculiar to stochastic reaction networks of multiple enzymes. Networks of single enzymes do not admit such transients. The transient yields, asymptotically, to a steady-state in which memory vanishes and hyperbolicity is recovered. We propose new statistical measures, defined in terms of turnover times, to distinguish between the transient and steady-states and apply these to experimental data from a landmark experiment that first observed molecular memory in a single enzyme with multiple binding sites. Our study shows that catalysis at the molecular level with more than one enzyme always contains a non-classical regime and provides insight on how the classical limit is attained.
Evolutionary dynamics of cooperation with the celebrity effect in complex networks
Authors: Fu Yanyu , Zhang Yan , Guo Yu , Xie Yunya
Published: January 2021

How long-term cooperation is maintained in a society is an important and interesting question. The evolutionary game theory is often used as the basic framework to study this topic. The social status of game participants has an important influence on individual decision-making. Enlightened by this thought, we present a classification imitation model where the mechanisms of the celebrity effect and incomplete egoism are presented. The celebrity effect is reflected in each strategy update process to probe how individual decision-making is dynamically adjusted by comparing the social status of both parties in the game. The incomplete egoism refers to the irrational imitation of celebrities while self-interest is ignored. With this model, the group cooperation decision-making mechanism led by celebrities is revealed. Large-scale Monte Carlo simulations show that the incomplete egoism of individuals cannot stimulate cooperation but guarantee the stable existence of cooperation. Furthermore, the scale-free and community structure of the network enables cooperation to spread widely and maintains long-term survival. Our conclusion might provide practically new insight into the understanding and controlling of cooperation in the complex social systems.
Laser-plasma acceleration beyond wave breaking
Authors: Palastro J. P. , Malaca B. , Vieira J. , Ramsey D. , Simpson T. T. , Franke P. , Shaw J. L. , Froula D. H.
Published: January 2021

Laser wakefield accelerators rely on the extremely high electric fields of nonlinear plasma waves to trap and accelerate electrons to relativistic energies over short distances. When driven strongly enough, plasma waves break, trapping a large population of the background electrons that support their motion. Aside from limiting the maximum electric field, this trapping can lead to accelerated electron bunches with large energy spreads. Here, we introduce a novel regime of plasma wave excitation and wakefield acceleration that allows for arbitrarily high electric fields while avoiding the deleterious effects of unwanted trapping. The regime, enabled by spatiotemporal shaping of laser pulses, exploits the property that nonlinear plasma waves with superluminal phase velocities cannot trap charged particles and are therefore immune to wave breaking.
Ion Migration in Metal Halide Perovskites Solar Cells
Authors: Khan Rashid , Ighodalo Kester O. , Xiao Zhengguo
Published: January 2021

Metal halide perovskites (MHPs) have been in the spotlight of the solar cell community in recent years due to their rapid increase in power conversion efficiency. The certified power conversion efficiency of perovskite solar cells (PSCs) has reached a high value of 25.5%, closing to its Shockley–Queisser limit and approaching that of crystalline silicon solar cells. However, it has been acknowledged that ion migration, an intrinsic property of MHPs causing many undesirable changes in PSCs, such as large current-voltage hysteresis curves, poor stability, low conductivity, phase segregation, etc., leads to PSCs degradation. In this chapter, we review ion migration in PSCs. We will cover topics including ion migration species in MHPs, ion migration channels, the factors that influence ion migration, and the effect of ion migration on perovskite solar cells, as well as strategies to suppress ion migration.
Photophysics in organic solar cells
Authors: Zhong Yufei
Published: January 2021

Among many emerging materials for next-generation electronics, organic semiconductors started their photovoltaic journey over two decades ago. In spite of the high efficiency achieved to date (17%) in organic solar cells (OSCs; Lin et al., 2019), the puzzle of photophysical processes in devices is still not fully resolved. Due to the low dielectric constant (3–4 for polymers or small molecules) of organic semiconductors, the binding energy of excited states is too large to be conquered by thermal energy at room temperature. In other words, a tightly bounded electron-hole pair (exciton) instead of free charge carriers is generated after photoexcitation. Free carrier generation in organic semiconductors therefore requires an additional but indispensable process, namely, charge dissociation. Preceding chapters might have already illustrated in detail the photophysical processes, by means of material and device characterizations. This chapter herein describes these key processes in different manners, via ultrafast spectroscopic measurements. This chapter will focus on important photophysical processes directly visualized by transient absorption (TA) spectroscopy and other spectroscopic tools based on TA. Such real-time measurement offers a direct impression on how excited species such as excitons and polarons evolve with time. Furthermore, spectroscopic measurements based on the Stark effect reveal separation distance between electrons and holes, leading to the spatial information of free carriers at different time scales. These measurements are powerful tools showing an early stage of photogenerated species in femtosecond (fs) and picosecond (ps) time scales, bringing new insights on how to reduce energy loss in devices and hints on designing efficient material systems.
Approximation by simple partial fractions in unbounded domains
Authors: Borodin P. A. , Shklyaev K. S.
Published: January 2021

For unbounded simply connected domains

in the complex plane, bounded by several simple curves with regular asymptotic behaviour at infinity, we obtain necessary conditions and sufficient conditions for simple partial fractions (logarithmic derivatives of polynomials) with poles on the boundary of

to be dense in the space of holomorphic functions in

(with the topology of uniform convergence on compact subsets of

). In the case of a strip

bounded by two parallel lines, we give estimates for the convergence rate to zero in the interior of

of simple partial fractions with poles on the boundary of

and with one fixed pole.

Bibliography: 16 titles.
On a conjecture of Teissier: the case of log canonical thresholds
Authors: Elduque E. , Mustaţă M.
Published: January 2021

For a smooth germ of an algebraic variety

and a hypersurface

in

, with an isolated singularity at

, Teissier conjectured a lower bound for the Arnold exponent of

in terms of the Arnold exponent of a hyperplane section

and the invariant

of the hypersurface.

By building on an approach due to Loeser, we prove the conjecture in the case of log canonical thresholds.

Bibliography: 21 titles.
Astrocytic cAMP modulates memory via synaptic plasticity
Authors: Zhou Zhiwen , Okamoto Kazuki , Onodera Junya , Hiragi Toshimitsu , Andoh Megumi , Ikawa Masahito , Tanaka Kenji F. , Ikegaya Yuji , Koyama Ryuta
Published: January 2021

Significance

Astrocytes have been suggested as important modulators of memory. However, intracellular signaling that regulates astrocytic function in memory modulation remains to be clarified. Here, we generated a transgenic mouse line, Mlc1-bPAC, in which astrocytes increase their intracellular cAMP levels upon blue light stimulation. Using this method, we have uncovered that light-induced increase in astrocytic cAMP is sufficient to induce synaptic plasticity and modulate memory. Furthermore, we have shown that an increase in astrocytic cAMP activates the astrocyte–neuron lactate shuttle, which is essential for synaptic plasticity and memory modulation. These findings indicate the importance of astrocytic cAMP in synaptic plasticity and memory and provide a method for investigating astrocyte functions in vivo in the future.
Thermodynamics of interfaces extended to nanoscales by introducing integral and differential surface tensions
Authors: Dong W.
Published: January 2021

Significance

Our current knowledge about the thermodynamics for interfaces was essentially founded by Gibbs more than a century ago for macroscopic systems. The results presented in this work show that Gibbs thermodynamics for interfaces can be extended down to nanoscales if the new concepts of integral and differential surface tensions are introduced.
Effect of streaming velocity, magnetic field, and higher-order correction on the nature of ion acoustic solitons in the Venusian ionosphere
Authors: Fayad A A , Moslem W M , El-Labany S K
Published: January 2021

Propagation properties of weakly nonlinear ion acoustic waves are investigated in a plasma at the Venusian ionosphere. The plasma model consists of two positive cold ions (oxygen O
+ and hydrogen H
+), as well as isothermal electrons. The basic set of fluid equations is reduced to Zakharov-Kuznetsov (ZK) equation and linear inhomogeneous ZK-type equation (LIZKT) equation. The renormalization method is adopted to obtain solitary solutions of both equations. The effects of plasma parameters and higher-order correction on the nature of the solitary waves are investigated. It is found that the wave phase velocity is supersonic, which is in agreement with the observations. Furthermore, the higher-order correction enlarges the soliton amplitude, which is suitable for describing the solitary waves when the wave amplitude grows.
Plasmonic wideband and tunable absorber based on semi etalon nano structure in the visible region
Authors: Roostaei N , Mbarak H , Monfared S Almasi , Hamidi S M
Published: January 2021

In this study, a plasmonic meta-surface absorber by semi-etalon structure is introduced due to the importance of wideband absorbers in the visible region as solar absorber. For this purpose, soft nanolithography method was adopted to construct semi-etalon absorber based on poly-dimethyl-siloxane flexible membrane and gold grating structure onto its top and down side. In parallel, the structure was simulated by the aid of finite difference time domain method, and obtained good agreement between the measured and simulated results. The results indicated the etalon-based absorber achieved light absorption from 500 to 700 nm compared to one face gold grating which works in the wavelength range 500 to 600 nm with half of absorbed power. In addition, color production was evaluated via the proposed structure, and tunable colors were produced by changing the polarization and incidence angle. Thus, the proposed structure as a good wide-band absorber, and can be used for producing tunable colors under different polarization and incidence angles. The absorber can offer new insight in larger area solar absorber based on soft nano-lithography method because of the low cost and flexibility.