bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-loss single-mode hybrid-lattice hollow-core photonic-crystal fibre
Authors: Amrani Foued , Osório Jonas H. , Delahaye Frédéric , Giovanardi Fabio , Vincetti Luca , Debord Benoît , Gérôme Frédéric , Benabid Fetah
Published: January 2021

Remarkable recent demonstrations of ultra-low-loss inhibited-coupling (IC) hollow-core photonic-crystal fibres (HCPCFs) established them as serious candidates for next-generation long-haul fibre optics systems. A hindrance to this prospect and also to short-haul applications such as micromachining, where stable and high-quality beam delivery is needed, is the difficulty in designing and fabricating an IC-guiding fibre that combines ultra-low loss, truly robust single-modeness, and polarisation-maintaining operation. The design solutions proposed to date require a trade-off between low loss and truly single-modeness. Here, we propose a novel IC-HCPCF for achieving low-loss and effective single-mode operation. The fibre is endowed with a hybrid cladding composed of a Kagome-tubular lattice (HKT). This new concept of a microstructured cladding allows us to significantly reduce the confinement loss and, at the same time, preserve truly robust single-mode operation. Experimental results show an HKT-IC-HCPCF with a minimum loss of 1.6 dB/km at 1050 nm and a higher-order mode extinction ratio as high as 47.0 dB for a 10 m long fibre. The robustness of the fibre single-modeness is tested by moving the fibre and varying the coupling conditions. The design proposed herein opens a new route for the development of HCPCFs that combine robust ultra-low-loss transmission and single-mode beam delivery and provides new insight into IC guidance.
A modular microfluidic system based on a multilayered configuration to generate large-scale perfusable microvascular networks
Authors: Yue Tao , Zhao Da , Phan Duc T. T. , Wang Xiaolin , Park Joshua Jonghyun , Biviji Zayn , Hughes Christopher C. W. , Lee Abraham P.
Published: January 2021

The vascular network of the circulatory system plays a vital role in maintaining homeostasis in the human body. In this paper, a novel modular microfluidic system with a vertical two-layered configuration is developed to generate large-scale perfused microvascular networks in vitro. The two-layer polydimethylsiloxane (PDMS) configuration allows the tissue chambers and medium channels not only to be designed and fabricated independently but also to be aligned and bonded accordingly. This method can produce a modular microfluidic system that has high flexibility and scalability to design an integrated platform with multiple perfused vascularized tissues with high densities. The medium channel was designed with a rhombic shape and fabricated to be semiclosed to form a capillary burst valve in the vertical direction, serving as the interface between the medium channels and tissue chambers. Angiogenesis and anastomosis at the vertical interface were successfully achieved by using different combinations of tissue chambers and medium channels. Various large-scale microvascular networks were generated and quantified in terms of vessel length and density. Minimal leakage of the perfused 70-kDa FITC-dextran confirmed the lumenization of the microvascular networks and the formation of tight vertical interconnections between the microvascular networks and medium channels in different structural layers. This platform enables the culturing of interconnected, large-scale perfused vascularized tissue networks with high density and scalability for a wide range of multiorgan-on-a-chip applications, including basic biological studies and drug screening.
New insights into the biphasic “CO-free” Pauson–Khand cyclisation reaction through combinedin situspectroscopy and multiple linear regression modelling
Authors: Geitner Robert , Huang Tianbai , Kupfer Stephan , Gräfe Stefanie , Meirer Florian , Weckhuysen Bert M.
Published: January 2021

Multiple linear regression modelling is used to analysein situRaman spectra recorded during a “CO-free” Pauson–Khand type cyclisation which enables a knowledge-driven optimisation protocol.
Direct visible photoexcitation on palladium nanocatalysts by chemisorption with distinct size dependence
Authors: Xiao Qi , Sarina Sarina , Waclawik Eric R. , Zhu Huaiyong
Published: January 2021

Direct photoexcitation of metal nanoparticles (NPs) can induce selective chemical reactions that are difficult to achieve with thermal energy.
A combined experimental and theoretical rationalization of an unusual zinc(ii)-mediated conversion of 18-membered Schiff-base macrocycles to 18-membered imine–amine macrocycles with imidazolidine side rings: an investigation of their bio-relevant catalytic activities
Authors: Chakraborty Tonmoy , Mukherjee Somali , Parveen Rumana , Chandra Arpita , Samanta Debabrata , Das Debasis
Published: January 2021

Macrocyclic Zn(ii)-based Schiff base complexes exhibit significant phosphatase-like activity as well as high potential anticancer activity against breast cancer cells.
Two novel nickel cluster substituted polyoxometalates: syntheses, structures and their photocatalytic activities, magnetic behaviors, and proton conduction properties
Authors: Chen Yi , Guo Zheng-Wei , Chen Ya-Peng , Zhuang Zan-Yong , Wang Guo-Qiang , Li Xin-Xiong , Zheng Shou-Tian , Yang Guo-Yu
Published: January 2021

A Ni12-substituted POM and a Ni6-substituted POM have been synthesized and characterized. The compounds show a moderate catalytic activity in visible-light-driven CO2 reduction reactions, and can serve as potential proton conduction materials.
Recent progress in chemical approaches for the development of novel neuraminidase inhibitors
Authors: Mahal Ahmed , Duan Meitao , Zinad Dhafer S. , Mohapatra Ranjan K. , Obaidullah Ahmad J. , Wei Xiaoyi , Pradhan Manoj K. , Das Debadutta , Kandi Venkataramana , Zinad Hany S. , Zhu Quanhong
Published: January 2021

Influenza virus is the main cause of an infectious disease called influenza affecting the respiratory system including the throat, nose and lungs.
A self-supported electrode for supercapacitors based on nanocellulose/multi-walled carbon nanotubes/polypyrrole composite
Authors: Lv Peng , Meng Yeyun , Song Lingxia , Pang Hao , Liu Weiqu
Published: January 2021

A robust self-supported electrode was prepared by a facile combination of ultrasonic dispersion and consequent in situ polymerization.
Calcination-free production of calcium hydroxide at sub-boiling temperatures
Authors: Vallejo Castaño Sara , Callagon La Plante Erika , Shimoda Sho , Wang Bu , Neithalath Narayanan , Sant Gaurav , Pilon Laurent
Published: January 2021

A calcination-free route to produce calcium hydroxide from alkaline industrial wastes including leaching, concentration, and temperature-swing precipitation.
Directional effect on the fusion of ellipsoidal morphologies into nanorods and nanotubes
Authors: Li Yahui , Lu Qunzan , Chen Qiumeng , Wu Xuan , Shen Jianliang , Shen Liangliang
Published: January 2021

Herein, a directional fusion of ellipsoidal morphologies into nanorods and nanotubes was demonstrated through the study of polymerization-induced self-assembly behaviors of semi-fluorinated liquid-crystalline block copolymers.
2D layered metal-halide perovskite/oxide semiconductor-based broadband optoelectronic synaptic transistors with long-term visual memory
Authors: Park Youngjun , Kim Min-Kyu , Lee Jang-Sik
Published: January 2021

High-performance optoelectronic synaptic transistors are reported with a long-term memory by using organic–inorganic halide perovskites and oxide semiconductors.
BEAST begins: sample characteristics and survey performance of the B-star Exoplanet Abundance Study
Authors: Janson Markus , Squicciarini Vito , Delorme Philippe , Gratton Raffaele , Bonnefoy Mickaël , Reffert Sabine , Mamajek Eric E. , Eriksson Simon C. , Vigan Arthur , Langlois Maud , Engler Natalia , Chauvin Gaël , Desidera Silvano , Mayer Lucio , Marleau Gabriel-Dominique , Bohn Alexander J. , Samland Matthias , Meyer Michael , d’Orazi Valentina , Henning Thomas , Quanz Sascha , Kenworthy Matthew , Carson Joseph C.
Published: January 2021

While the occurrence rate of wide giant planets appears to increase with stellar mass at least up through the A-type regime, B-type stars have not been systematically studied in large-scale surveys so far. It therefore remains unclear up to what stellar mass this occurrence trend continues. The B-star Exoplanet Abundance Study (BEAST) is a direct imaging survey with the extreme adaptive optics instrument SPHERE, targeting 85 B-type stars in the young Scorpius-Centaurus (Sco-Cen) region with the aim to detect giant planets at wide separations and constrain their occurrence rate and physical properties. The statistical outcome of the survey will help determine if and where an upper stellar mass limit for planet formation occurs. In this work, we describe the selection and characterization of the BEAST target sample. Particular emphasis is placed on the age of each system, which is a central parameter in interpreting direct imaging observations. We implement a novel scheme for age dating based on kinematic sub-structures within Sco-Cen, which complements and expands upon previous age determinations in the literature. We also present initial results from the first epoch observations, including the detections of ten stellar companions, of which six were previously unknown. All planetary candidates in the survey will need follow up in second epoch observations, which are part of the allocated observational programme and will be executed in the near future.
Features of the organization of agroclusters in the structure of land management projects
Authors: Mukumov Abdugani , Xujakeldiev Komil , Xamidov Fayzullo , Narbaev Sharafatdin , Abdivaitov Khudoyberdi
Published: January 2021

The features of the organization of production units agroclusters, which are one of the components of land management projects which aimed at organizing the rational and efficient use of available land resources are described in this article. The term “cluster” is a French word that means “bundle”, “collection” in Uzbek. It can be taken as “the geographical proximity of enterprises and institutions cooperating with each other in a particular field”. The development of value-added production in the agricultural sector and the development of this market requires ensuring product quality standards, full use of scientific and scientific achievements in the processing process, development of existing research institutes and using the potential of geographical location. In our view, the solution of this problem can be found in the agricultural production system through the organization of cluster production, which is used by developed countries in America, Europe and Asia.
Influence of Adverse Ecological Factors on the Incidence of Malignant Neoplasms
Authors: Turdimambetov Izimbet , Madreymov Amet , Foldvary Lorant , Oteuliev Medetbay , Kurbanov Murat , Utarbaeva Kamila , Bekanov Kuatbay
Published: January 2021

An analysis of the leading sanitary-ecological factors of the environment affecting the incidence rates among the population of the Republic of Karakalpakstan in 2009-2018 found that between the indicators of the primary incidence of malignant neoplasms and water samples of open reservoirs that are not standard in chemical composition, strong direct correlations in the Northern (rxy = 0.89) zone, average direct correlations in the Western (rxy = 0.67) and Central (rxy = 0.57) zones were established. Similarly, strong connection was found in the Chimbay (rxy = 0.73) district, moderate correlation in Nukus (rxy = 0.44) and Ellikkala (rxy = 0.66) districts. The moderate correlation of the dynamics of malignant neoplasms with indicators of chemical pollution of tap water in the Chimbay (rxy = 0.33) district, well water in Kanlykul (rxy = 0.32) and atmospheric air in the city of Nukus (rxy = 0.41) was revealed and in the Republic of Karakalpakstan (rxy = 0.39). The solution to the problem lies in providing for the population of the selected districts with centralized drinking water that meets the state standard.
Experience in creating a soil-reclamation map of the Zarafshan river valley based on the system analysis of lithodynamic flow structures
Authors: Sabitova Naila , Ruzikulova Oykhumor , Aslanov Ilhomjon
Published: January 2021

Analysis of lithodynamic flows and soil-reclamation studies, based on the plastic relief map, allowed for a systematic analysis of the main components of the natural environment. The ways of migration of chemical elements in the soil are established. For the first time, causal relationships of spatial differentiation of the degree and chemical composition of saline soils in the Zarafshan river valley were revealed. The Zarafshan river basin has a clearly defined border, as we can judge from the map of plastic relief made up in 1: 100 000 scale. Here three cascade systems are well distinguished, which is very important for the formation of the reclamation state of the territory. In this area, that is, the subsystem, on the proluvial-alluvial deposits is the main volume of groundwater, which is closely related to the surface. This subsystem is part of the catchment area of the Zarafshan river basin, which is the main source of removal from the territory of a huge mass of dissolved and solid substances.
Deformation analysis based on GNSS measurements in Tashkent region
Authors: Fazilova Dilbarkhon Sh. , Sichugova Lola V.
Published: January 2021

This paper presents the results of the GNSS geodetic network deformation analysis in the Tashkent region, as an example of an urban area, where obtaining reliable information for assessing hazard risk is of great importance. A software package in Delphi language has been developed for the assessment of the datum differences between 2009 and 2011 by implementing the 3D Helmert transformation method. The result revealed that there is significant translation and rotation in the network, while the scale of the network remains almost constant during two years period. The area strain was estimated by the finite element method. Most of the Tashkent region can be considered to be in a high compression (negative dilatation) strain state with maximum value -230cl0-8. On the contrary, remarkable positive dilatation strain is concentrated on the coastline of the Charvak water reservoir, where large strain is about 351.l0-8.
Wheat harvesting by combine with GPS receiver and grain sensor
Authors: Astanakulov Komil , Shovazov Kodir , Borotov Atkham , Turdibekov Akram , Ibrokhimov Saidmukhammad
Published: January 2021

This research describes the result of study and analyze the working process of the harvester combine with GPS receiver and grain level sensor in wheat harvesting. GPS receiver and grain level sensor showed that the combine harvester was working with what level of velocity in the real time regime and how much grain was being uploaded into grain tank. According to results when the yield increased from 2.62 t/ha to 6.22 t/ha, because of decreasing the work-velocity of the combine harvester, the work efficiency of the combine harvester decreased from 1.96 ha/hour till 1.30 ha/hour, and grain loss rose from 2.03 per cent till 3.76 per cent. In the field where the weeds had covered 16.8 per cent, the work efficiency of the combine was 1.74 ha/hour, in another field where weeds level was 56.7 the work efficiency of the combine decreased almost 1.7 times, made up 1.07 ha/hour, the grain loss was observed that it increased from 2.1 per cent till 7.42 per cent. When the moisture of the cereal decreased it was defined that the combine work efficiency increased, however the rate of grain loss in the header rose too.
Shaft hoist rope wear condition as a diagnostic signal
Authors: Mańka Eugeniusz , Styp-Rekowski Michał , Matuszewski Maciej , Pimenov Danil Y.
Published: January 2021

In the paper there were discussed factors which determine wear process intensity of shaft hoist rope. The ropes as the element or the elements set are appearing in numerous, diverse machines and mechanisms, fulfilling the most different functions in them. Mining shaft hoists are a very representative example of the object being used for a vertical transport, of both the staff of the mine and winning. Results of experimental investigations of rope were presented. Findings obtained different methods were compared.
Selected aspects of diagnosing material removal machining processes state
Authors: Polasik Robert , Musiał Janusz , Jasik Jarosław , Kovtun Igor , Povareho Aleksandr
Published: January 2021

The article presents the results of works on the analysis of the possibility of using force measurements to determine the state of the machining process, both in relation to the phenomena occurring during machining and the workpiece itself compared to acoustic emission signal (AE). The research and analyzes were carried out for the commonly used material removal processes of objects; turning, milling, grinding and drilling. Various materials were processed - metal alloy Hardox 400 as well as fiber composite materials (GFRP - Glass Fiber Reinforced Polymer) and polymer construction material RenShape® BM5035 with various structures. As a result of the conducted analyzes, it was determined that the forces generated in the machine tool-holder-workpiece-tool layout can constitute a good diagnostic signal, on the basis of which it is possible to conclude about the state of the process.
Analysis of selected geometrical features of a structural element on the example of a dental implant
Authors: Imiłkowski Szymon , Kovalyshyn Stepan , Karolewska Karolina , Ligaj Bogdan , Wirwicki Mateusz
Published: January 2021

The aim of the article was to carry out FEM strength tests for four proposed by the authors geometry of the intraoral implant. Change of their geometrical features to find the most optimal distribution of reduced stresses. The article presents various geometries of the new dental implant. Strength tests were performed using the finite element method (FEM). The results of the tests were analyzed and their assessment was made for which of the solutions of the new geometry the stress distribution is the most optimal. Detailed results of the analyzes for a given model are shown and new solutions in the construction of the implant are proposed.
Analysis of selected performance parameters of a drive unit fueled by biocomponents
Authors: Markiewicz Marietta
Published: January 2021

The most desirable effect of motorization development is obtainment of high performance power units. Ecological requirements, however, and exhaustibility of the earth natural resources limit the possibilities of self-ignition engines. The study presents analyses of power and torque of a self-ignition engine fueled with mixtures of diesel and fatty acid methyl esters. The tests show that application of a biocomponent additive to diesel fuel slightly reduces the value of power and torque of the tested vehicle. Moreover, as proven by other tests, application of such mixtures causes an increase in the number of components in the exhaust gases and emission of sound generated by a power unit. The study shows only some of the tests performed to reflect significant performance parameters of transport means.
Identification of loads of the construction of a Hybrid Multimedia Mobile Stage
Authors: Liss Michał , Kałaczyński Tomasz , Dluhunovych Natalia , Dykha Aleksandr , Martinod Ronald M.
Published: January 2021

The construction of the mobile stage is a huge challenge for designers due to a very wide range of variable factors affecting it, such as wind or temperature, the value of which in this case depends on the geographical location. An inherent element of the influence of these factors are the accompanying various, both constant and variable loads. Detailed identification of these loads is extremely important both for the safety of use and the diagnostic possibilities of such a complex mechanical structure.
Neurodevelopmental Outcome in Very Low Birth Weight Infants Exposed to Donor Milk
Authors: Patra Kousiki , Greene Michelle M. , Tobin Grace , Casini Gina , Esquerra-Zwiers Anita L. , Meier Paula P. , Patel Aloka L.
Published: January 2021

Objective This study was aimed to evaluate the impact of donor milk (DM) received in the first 28 days of life (DOL) on neurodevelopmental (ND) outcome at 20-months corrected age (CA) in very low birth weight (VLBW) infants.

Study Design A total of 84 infants born in 2011 to 2012 who received only mother's own milk (MOM) and/or preterm formula (PF) was compared with 69 infants born in 2013 to 2014 who received MOM and/or DM. Daily enteral intake of MOM, DM, and PF was collected through 28 DOL. ND outcomes were assessed with the Bayley-III. Multiple regression analyses adjusted for the effect of social and neonatal risk factors alongside era of birth on ND outcome.

Results Infants exposed to DM were born to older mothers (p < 0.01) and had higher incidence of severe brain injury (p = 0.013). Although DM group infants received first feed at earlier DOL (p < 0.001), there were no differences in MOM intake at DOL 14 or 28 between the two groups. In regression analyses, DM group did not predict 20-month ND outcome.

Conclusion There were no differences in ND outcome between infants born before and after the introduction of DM. This may have been due to the similar percent of MOM at DOL 14 and 28 in the two eras.

Key Points
Enhancement of dynamical robustness in a mean-field coupled network through self-feedback delay
Authors: Sharma Amit , Rakshit Biswambhar
Published: January 2021

The network of self-sustained oscillators plays an important role in exploring complex phenomena in many areas of science and technology. The aging of an oscillator is referred to as turning non-oscillatory due to some local perturbations that might have adverse effects in macroscopic dynamical activities of a network. In this article, we propose an efficient technique to enhance the dynamical activities for a network of coupled oscillators experiencing aging transition. In particular, we present a control mechanism based on delayed negative self-feedback, which can effectively enhance dynamical robustness in a mean-field coupled network of active and inactive oscillators. Even for a small value of delay, robustness gets enhanced to a significant level. In our proposed scheme, the enhancing effect is more pronounced for strong coupling. To our surprise even if all the oscillators perturbed to equilibrium mode were delayed negative self-feedback is able to restore oscillatory activities in the network for strong coupling strength. We demonstrate that our proposed mechanism is independent of coupling topology. For a globally coupled network, we provide numerical and analytical treatment to verify our claim. To show that our scheme is independent of network topology, we also provide numerical results for the local mean-field coupled complex network. Also, for global coupling to establish the generality of our scheme, we validate our results for both Stuart–Landau limit cycle oscillators and chaotic Rössler oscillators.
Evolution of the self-injection process in long wavelength infrared laser driven LWFA
Authors: Kumar Prabhat , Yu Kwangmin , Zgadzaj Rafal , Downer Michael , Petrushina Irina , Samulyak Roman , Litvinenko Vladimir , Vafaei-Najafabadi Navid
Published: January 2021

Long wavelength infrared laser-driven plasma wakefield accelerators are investigated here in the self-modulated laser wakefield acceleration (SM-LWFA) and blowout regimes using 3D particle-in-cell simulations. The simulation results show that in the SM-LWFA regime, self-injection arises with wave breaking, whereas in the blowout regime, self-injection is not observed under the simulation conditions. The wave breaking process in the SM-LWFA regime occurs at a field strength that is significantly below the 1D wave-breaking threshold. This process intensifies at higher laser power and plasma density and is suppressed at low plasma densities (≤1×1017cm−3 here). The produced electrons show spatial modulations with a period matching that of the laser wavelength, which is a clear signature of direct laser acceleration.
Large-scale circulation and oscillation in turbulent Rayleigh–Bénard convection with a Prandtl number Pr = 12.3
Authors: Wei Ping
Published: January 2021

An experimental study of the three-dimensional spatial structure of low-frequency temperature oscillations in cylindrical Rayleigh–Bénard convection of a fluid with a Prandtl number Pr = 12.3, aspect ratio Γ ≡ D/L = 1.00 (D is the diameter, and L is the height) and Rayleigh-number 5 × 1010 < Ra < 3 × 1011 is reported. The flow structure was measured using 3 sets of 8 thermal probes, each distributed uniformly around the periphery at heights L/4, L/2, and 3L/4 from the bottom. At the top/bottom layer, the large-scale circulation (LSC) consisted of two well-identified cold/hot flows. These cold/hot flows traveled to mid-height, where only the fluctuation in the temperature reveals the existence of two cold/hot flows. The oscillatory frequency corresponding to the turnover frequency of the LSC was only found at the location where the cold/hot flows were present. There is a discrepancy between the Reynolds number based on the turnover frequency of the LSC in the present work and GL prediction. This discrepancy is consistent with the study by Brown, Funfschilling, and Ahlers (J. Stat. Mech. 2007, P10005-1–P10005-22), indicating that there is a new state in Ra > Ra* where the LSC is no longer a coherent single-roll structure. Ra* for Pr = 12.3 is 1 × 1010.
An embedded atom model for Ga–Pd systems: From intermetallic crystals to liquid alloys
Authors: Wonglakhon Tanakorn , Maisel Sven , Görling Andreas , Zahn Dirk
Published: January 2021

We present an embedded atom model (EAM) potential for modeling Ga–Pd interactions within intermetallic solids and liquid alloys. The molecular mechanics potential was parameterized on the basis of the structure and mechanical properties of GaPd2, whereas a series of other GaxPd1–x phases and liquid alloy systems allowed rigorous benchmarking. For the intermetallic solids, structures and elastic moduli were found in very reasonable agreement with experimental structures and results from DFT calculations. The liquid models were characterized from molecular dynamics simulations that also showed nice agreement with experimental and ab initio reference data. Moreover, the perspectives of the EAM model are illustrated by the elucidation of an alloy nanodroplet model whose characterization includes the kinetics of Pd dopant diffusion from the Ga droplet surface to the bulk liquid and vice versa.
Tuning spin–orbit coupling in (6,5) single-walled carbon nanotube doped with sp3 defects
Authors: Trerayapiwat Kasidet Jing , Lohmann Sven , Ma Xuedan , Sharifzadeh Sahar
Published: January 2021

Single-walled carbon nanotubes (SWCNTs) containing sp3 defects are a promising class of optoelectronic materials with bright photoluminescence and demonstrated single-photon emission. Using density functional theory simulations, complemented by measurements, we investigate the electronic structure of a series of quantum defects attached to (6,5) SWCNT with the goal of tuning the spin–orbit coupling by introduction of a heavy atom in the defect structure. We characterize the ground state electronic and spin properties of four synthesized and three potential defects on the tube and find that all of the synthesized defects considered introduce a localized midgap defect-centered state containing a single electron, ≈0.2–0.3 eV above the valence band. The spin density is located at the sp3 defect site with negligible spin–orbit coupling even with the presence of a Pd atom. Three additional functional groups were tested via computation to increase spin localization near the metal, thereby increasing spin–orbit coupling. We predict that only the chlorodiphosphanepalladium(II)– [Cl(PH3)2Pd(II)–] defect results in increased spin–orbit splitting of the defect state and the conduction band associated with the pristine-like SWCNT, a measure of the spin–orbit coupling of excited state transitions. This study suggests that for unpassivated sp3 defects in (6,5) SWCNT, forming a direct bond between a heavy atom and the sp3 carbon allows for tuning of spin–orbit coupling.
A high-efficiency cross-band Cerenkov microwave generator with a resonant reflector
Authors: Zhao Chenyu , Chi Hang , Ge Xingjun , Song Lili , He Juntao , Zhang Jun
Published: January 2021

High efficiency and short saturation time have great significance on the practical work of high power microwave devices. A dual-band Cerenkov microwave generator with high-efficiency based on electrical tuning is presented in this paper. Two-segment slow wave structures for the C-band and X-band separately are adopted, which are isolated by a drift cavity. The collimating hole is replaced by a resonant reflector, which can effectively shorten the saturation time. Moreover, in order to realize dual-band microwave output, the electrical tuning method is used in this paper. In particle-in-cell simulation, when the guiding magnetic field is 0.7 T, the output microwaves at the X-band can be obtained with an efficiency of 38% and saturation time for nearly 20 ns; when the guiding magnetic field is 1.5 T, the output microwaves at the C-band can be obtained with an efficiency of 32% and saturation time for nearly 20 ns. Thus, microwaves at the X-band and C-band can be generated separately by modulating the guiding magnetic field, which can be realized just by altering the current in the magnetic coil. It should be mentioned that such a modulating method is much more convenient than mechanical modulation.
First-principles study on non-radiative carrier captures of point defects associated with proton generation in silica
Authors: Yue Yunliang , Zhu Haoran , Liu Xiao , Song Yu , Zuo Xu
Published: January 2021

The non-radiative carrier captures of point defects associated with proton generation in both crystalline (α-quartz) and amorphous silica (a-SiO2) have been investigated by using first-principles calculations based on the density functional theory. Major point defects related to proton generation are considered, including the dimer and puckered configuration of oxygen vacancy, doubly hydrogenated oxygen vacancy, and hydroxyl E′ center. The carrier capture cross sections of the defects are calculated in terms of a one-dimensional static coupling method. The neutral dimer and doubly hydrogenated oxygen vacancies show a large hole capture cross section, and the positively charged puckered oxygen vacancy and the hydroxyl E′ center show a large electron capture cross section. These results further support that dissociation of molecular hydrogen at a positively charged dimer oxygen vacancy and that of a positively charged doubly hydrogenated oxygen vacancy are the main reactions in silica to generate protons that play a key role in ionization damage of silicon devices.
Magnetic textures in hemispherical thin film caps with in-plane exchange bias
Authors: Tomita Andreea , Reginka Meike , Huhnstock Rico , Merkel Maximilian , Holzinger Dennis , Ehresmann Arno
Published: January 2021

Hemispherical caps of in-plane exchange biased IrMn/CoFe layer systems have been fabricated on top of regularly arranged spherical silica particles by magnetron sputtering, creating magnetic Janus particles. In this thin film layer system cap, the magnetic shape anisotropy of the topographically non-flat hemispheres competes with the unidirectional anisotropy induced by the exchange bias. The magnetic properties of this non-trivial system have been investigated by longitudinal magneto-optical Kerr effect magnetometry, where a characterization method has been developed considering both the curved layer system and the signal contributions of flat parts of the sputtered thin film system. Both remagnetization curves, from Kerr magnetometry and the magnetic force microscopy images, reveal an onion state in the magnetic caps of the ensemble. Additional micromagnetic simulations show a stabilization of the onion state due to the introduced unidirectional anisotropy also in individual hollow hemispheres as compared to the vortex state exhibited by purely ferromagnetic caps.
Multi-shot damage on Mo/Si multilayer induced by nanosecond EUV radiation
Authors: Li Wenbin , Pan Liuyang , Wang Chunlin , Zhang Zhe , Xie Chun , Huang Qiushi , Wang Zhanshan
Published: January 2021

As a vital optical element working in the extreme ultraviolet (EUV) region, the damage mechanism on a Mo/Si multilayer has caught great attention. In this paper, using a nanosecond table-top EUV source, an S-on-1 EUV damage experiment was performed on a Mo/Si multilayer mirror with shot numbers S = 1, 2, 5, and 10. It was demonstrated that the multi-shot damage thresholds follow an inverse-power-law as a function of the pulse number. The incubation effect is explained based on the measured damage morphologies by an atomic force microscope. When the Mo/Si multilayer mirror was exposed to the EUV fluence above the single damage threshold, compaction of the layer structure and melting and resolidification processes are dominating the damage mechanism. It was also found that the crater depth and FWHM at high fluence are independent of the shot numbers, which is explained by the formation of the MoSi2 spacing layer.
Local embedding of coupled cluster theory into the random phase approximation using plane waves
Authors: Schäfer Tobias , Libisch Florian , Kresse Georg , Grüneis Andreas
Published: January 2021

We present an embedding approach to treat local electron correlation effects in periodic environments. In a single consistent framework, our plane wave based scheme embeds a local high-level correlation calculation [here, Coupled Cluster (CC) theory], employing localized orbitals, into a low-level correlation calculation [here, the direct Random Phase Approximation (RPA)]. This choice allows for an accurate and efficient treatment of long-range dispersion effects. Accelerated convergence with respect to the local fragment size can be observed if the low-level and high-level long-range dispersions are quantitatively similar, as is the case for CC in RPA. To demonstrate the capabilities of the introduced embedding approach, we calculate adsorption energies of molecules on a surface and in a chabazite crystal cage, as well as the formation energy of a lattice impurity in a solid at the level of highly accurate many-electron perturbation theories. The absorption energy of a methane molecule in a zeolite chabazite is converged with an error well below 20 meV at the CC level. As our largest periodic benchmark system, we apply our scheme to the adsorption of a water molecule on titania in a supercell containing more than 1000 electrons.
Nonintrusive manufactured solutions for ablation
Authors: Freno Brian A. , Carnes Brian R. , Matula Neil R.
Published: January 2021

The study of heat transfer and ablation plays an important role in many problems of scientific and engineering interest. As with the computational simulation of any physical phenomenon, the first step toward establishing credibility in ablation simulations involves code verification. Code verification is typically performed using exact and manufactured solutions. However, manufactured solutions generally require the invasive introduction of an artificial forcing term within the source code such that the code solves a modified problem for which the solution is known. In this paper, we present a nonintrusive method for manufacturing solutions for a non-decomposing ablation code, which does not require the addition of a source term.
Magnetization and thickness dependent microwave attenuation behaviour of Ferrite-PANI composites and embedded composite-fabrics prepared by in situ polymerization
Authors: Kumar Sumit , Verma Vivek , Walia Rajan
Published: January 2021

Ultrahigh efficient and effective electromagnetic-interference (EMI) shielding composites have been fabricated with the combination of Polyaniline and zinc-cobalt ferrites (Co1-xZnxFe2O4, 0.1 ≤ x ≤ 0.4). Ferrite nanoparticles synthesized via the sol-gel method were functionalized to polyaniline via in situ polymerization. Average crystallite sizes of the nanoparticles were estimated using Debye–Scherrer and Rietveld method and found to be in between 20-30 nm. FTIR spectra revealed the formation of interactions between the PANI molecules and the ferrite nanoparticles. Substitution of the nonmagnetic Zn ions considerably changes the magnetic properties of cobalt ferrites as observed from the M-H loops recorded by VSM at room temperature. The EMI-shielding performance of the fabricated composites was examined at various thicknesses with the polymer filler ratio of 1:1 in X-band frequency region using a vector network analyser. The EMI shielding performance of composites was found to be increasing with the thickness of composites where a thickness of 3.0 mm achieved an SE of ∼ 100 dB for the Co0.7Zn0.3Fe2O4-PANI composite. Composite absorbers were deposited on cotton fabrics for protective clothing by in situ incorporation during the synthesis of composites which displayed relatively high EMI shielding effectiveness (SE) (40-45 dB) at a thickness of only 0.30 mm for the fabrics. The PANI-Ferrite nanocomposites can be established as promising high capacity electromagnetic shielding materials because of the dipole polarization and the magnetic losses with low cost, lightweight, high durability and good flexibility.
Influence of varying particle sizes on microwave absorbing properties of U-type hexaferrites and development of broadband microwave absorber
Authors: Kumar Sandeep , Ghosh Narendra Nath , Chatterjee Ratnamala
Published: January 2021

The present study investigates the influence of particle size variation on the microwave (MW) absorbing properties of (Ba0.7Bi0.3)4Co2Fe34.8Zn1.2O60 U-type hexaferrites. The hexaferrite powders of varying particle sizes were prepared through heating at a constant optimized temperature for different holding time (4, 6, 8 and 10 h) using a novel “one-pot” chemical route. With an increase of the holding time (4 to 10 h), the average particle size is found to increase monotonically (∼65 to ∼170 nm). The hexaferrite sample prepared at a holding time of 8 h exhibits an excellent reflection loss (RL) of ‒44.2 dB (99.99% MW absorption) at 11.6 GHz frequency. In addition, a broadband MW absorber has been developed through an ingenious blending of equal amounts of all four hexaferrite powders. The mixed U-type hexaferrite displays an excellent bandwidth of ∼8.4 GHz for 90% or more MW absorption. The reflection losses (S11) are also measured experimentally through one port short-circuited transmission line method using vector network analyzer (VNA). The strong and broadband absorption results suggest that the prepared U-type samples can be utilized in the high-performance MW absorbing applications.
Hard magnetic properties of FeCoNiAlCuXTiX based high entropy alloys
Authors: Na Suok-Min , Lambert Paul K. , Jones Nicholas J.
Published: January 2021

High entropy alloys (HEA) contain multiple principal alloying elements, and possess unique properties due to the high configurational entropy and lattice strain in the system. Ferromagnetic FeCoNi-based HEAs exhibit dramatic changes in crystal structure and the type of magnetism expressed when adding non-magnetic elements such as Al, Cr, Ga, Ti, etc. Interestingly, Alnico permanent magnets also contain multiple principal alloying elements, such as Fe, Co, Ni, and Al, along with other minor additions. This well-studied system is similar in concept to high entropy alloys (HEAs). In this paper, we investigate the hard magnetic properties of FeCoNiAl-based HEAs with additions of Cu/Ti. The addition of Cu/Ti to an equimolar FeCoNiAl alloy is effective at enhancing coercivity, due to spinodal decomposition, but at the expense of saturation magnetization. By varying the ratio of Fe and Co, however, with respect to the other alloying elements, the saturation magnetization is increased, while generally retaining or improving the coercivity. In particular, the Fe2CoNiAlCu0.4Ti0.4 HEA shows promising hard magnetic properties as an isotropic cast magnet, with an HC of 1,078 Oe and (BH)max of 2.06 MGOe, slightly better than the performance of isotropic cast Alnico 2 magnets. The thermal stability is also sufficient for use at elevated temperatures over 200 °C. There was also an interesting increase in high temperature coercivity observed at temperatures from ∼650-800 °C, where these alloys often exhibited higher coercivity than that measured at RT.
Spin glass effects in the (Cr84Re16)99.6Mn0.4 alloy
Authors: Jacobs B. S. , Sheppard C. J. , de Camargo P. C. , Prinsloo A. R. E.
Published: January 2021

The possible existence of the spin glass (SG) state in the (Cr84Re16)99.6Mn0.4 alloy was investigated using magnetisation measurements. The temperature dependence of magnetisation, M(T), indicated a splitting of the M(T) data in the zero-field-cooled (ZFC) and field-cooled (FC) curves at the pinning temperature, Tp which is an indication of magnetic anisotropy in the system. The (Cr84Re16)99.6Mn0.4 alloy showed time dependence of isothermal remanent magnetisation (IRM) measurements, which is a signature associated with canonical SG. Measurement of field dependence of magnetisation did not show saturation at the lowest temperature or highest magnetic field because of the lack of long-range magnetic ordering which is also a SG signature. Preliminary measurements indicate the possible existence of magnetic frustration leading to the SG state in the (Cr84Re16)99.6Mn0.4 alloy.
On the path to novel magnetic cores: Electromagnetic simulations of amorphous magnetic microwires for inductive applications
Authors: Johnson C. , Zhang X. , Li D. , del Real R. P. , Pakdelian S. , Vázquez M. , Lewis L. H. , Lehman B.
Published: January 2021

The potential of water-quenched amorphous magnetic microwires in magnetic core applications is assessed by electromagnetic simulation. Simulations were performed based on microwires incorporated into two configurations: (1) a regular rod inductor and (2) an air-gapped toroidal inductor. Each model utilizes a cylindrical magnetic element of 100 microns in diameter, surrounded by a copper winding element that carries an alternating current at a frequency f =100 kHz. These models considered amorphous Fe(Co)SiB microwires specified by their experimentally determined B-H response as well as two benchmark core materials – soft ferrite (MnZn-oxide type) and Metglas (2605SA1). Simulation results indicate that the microwire material exhibits a higher degree of magnetization alignment along its length under the electromagnetic field created by the loop current, relative to the other two cores. The microwire configuration also exhibits improved core inductance by as much as 30% compared to those of the other two materials. These results demonstrate that amorphous magnetic microwires have intriguing potential in inductive applications.
Negative selection on human genes underlying inborn errors depends on disease outcome and both the mode and mechanism of inheritance
Authors: Rapaport Franck , Boisson Bertrand , Gregor Anne , Béziat Vivien , Boisson-Dupuis Stéphanie , Bustamante Jacinta , Jouanguy Emmanuelle , Puel Anne , Rosain Jérémie , Zhang Qian , Zhang Shen-Ying , Gleeson Joseph G. , Quintana-Murci Lluis , Casanova Jean-Laurent , Abel Laurent , Patin Etienne
Published: January 2021

Significance

While human genes underlying monogenic disorders are expected to undergo negative selection, the factors that impact the intensity of negative selection remain unknown. We find pervasive negative selection at genes underlying both autosomal dominant and the most severe autosomal recessive inborn errors. Among genes underlying dominant disorders, we show that loss of function entails stronger selection than gain of function, and haploinsufficiency than negative dominance. We develop a method that predicts whether an autosomal gene is more likely to underlie a recessive or a dominant disease. These results have evolutionary implications for studies of the drivers of negative selection, and practical implications in the search for genes underlying life-threatening, heritable conditions.
A dual-driven biomimetic microrobot based on optical and magnetic propulsion
Authors: Jiang Wei , Ye Guoyong , Chen Bangdao , Liu Hongzhong
Published: January 2021

The microrobot, which can address the fuel depletion and wire limitation, has exhibited great potential in the fields of lab-on-chip devices, sensing and monitoring devices, and some biomedical applications. In this paper, a dual-driven wireless microrobot, which can harvest and convert external optical and magnetic energy into the kinetic energy, is described. The dual-driven microrobot is fabricated by using a rapid 3D printing technology. Au and Ni nanoparticles are deposited on the surface of the microrobot, responsible for the optical and magnetic propulsion modes, respectively. The strong infrared light absorption of Au can induce a thermal convection and thus propel the movement of the microrobot. Similarly, the magnetic gradient ﬁeld exerted on the Ni nanoparticles is applied to enable the magnetic manipulation of the microrobot. The experimental results demonstrate that the applied magnetic field and laser beam can provide efﬁcient interventions on the ‘start/stop’ states, the speed and direction of the movement as well as the position of the microrobot in a remotely controlled manner. We can manipulate the microrobot with both fine microrange motion adjustment and wide range movement control that cannot be achieved by using a single propulsion mode. Dynamic switching of the light driven mode and the magnetic propulsion mode are also presented, which indicates that the microrobot can overcome the strong viscous force and display efﬁcient motions in fluids under each propulsion mode. Such dual-driven propulsion method offers a broad scope for designing smart micro-vehicles that can reconﬁgure their operation mode according to their mission and surrounding environments.
RF power transfer efficiency and plasma parameters of low pressure high power ICPs
Authors: Zielke D , Briefi S , Fantz U
Published: January 2021

Inductively coupled radio frequency (RF) ion sources operating at 1 MHz under the condition of a low gas pressure of 0.3 Pa are the basis of negative hydrogen/deuterium ionbased neutral beam injection systems of future fusion devices. The applied high RF powers of up to 75 kW impose considerable strain on the RF system and so the RF power transfer efficiency η becomes a crucial measure of the ion source’s reliability. η depends on external parameters such as geometry, RF frequency, power, gas pressure and hydrogen isotope. Hence, η along with the plasma parameters are investigated experimentally at the ITER prototype RF ion source. At only 45%–65% in hydrogen and an increase of around 5% in deuterium, η is found to be surprisingly low in this ion source. The power that is not coupled to the plasma is lost by Joule heating of the RF coil (∼26%) and due to eddy currents in the internal Faraday screen (∼74%). The matching transformer adds up to 8 kW of losses to the system. The low values of η and the high share of the losses in the Faraday screen and the transformer strongly suggest optimization opportunities. At high power densities well above 5 W cm−3, indications for neutral depletion as well as for the ponderomotive effect are found in the pressure and power trends of η and the plasma parameters. The comprehensive data set may serve for comparison with other RF ion sources and more standard inductively coupled plasma setups as well as for validating models to optimize RF coupling.