bluuebunny/crossref_metadata_2025 huggingface dataset:
Engineering the magnetocaloric properties of PrVO3 epitaxial oxide thin films by strain effects
Authors: Bouhani H. , Endichi A. , Kumar D. , Copie O. , Zaari H. , David A. , Fouchet A. , Prellier W. , Mounkachi O. , Balli M. , Benyoussef A. , El Kenz A. , Mangin S.
Published: August 2020

Combining multiple degrees of freedom in strongly correlated materials such as transition-metal oxides would lead to fascinating magnetic and magnetocaloric features. Herein, the strain effects are used to markedly tailor the magnetic and magnetocaloric properties of PrVO3 thin films. The selection of an appropriate thickness and substrate enables us to dramatically decrease the coercive magnetic field from 2.4 T previously observed in sintered PVO3 bulk to 0.05 T for compressive thin films making from the PrVO3 compound a nearly soft magnet. This is associated with a marked enhancement of the magnetic moment and the magnetocaloric effect that reaches unusual maximum values of roughly 4.86 μB and 56.8 J/kg K with the magnetic field change of 6 T applied in the sample plane in the cryogenic temperature range (3 K), respectively. This work strongly suggests that taking advantage of different degrees of freedom and the exploitation of multiple instabilities in a nanoscale regime is a promising strategy for unveiling unexpected phases accompanied by a large magnetocaloric effect in oxides.
Transport and fate of human expiratory droplets—A modeling approach
Authors: Wang Binbin , Wu Huijie , Wan Xiu-Feng
Published: August 2020

The transport and fate of human expiratory droplets play a key role in the transmission of respiratory infectious diseases. In this paper, we present a modeling approach to understand the fundamental dynamics of exhaled droplets in human respiratory activities. The model solves a series of governing equations of droplets and uses a continuous random walk model to simulate turbulent fluctuations in violent expiratory events. The validation of the model shows the improvement in the prediction of dispersion of median-sized droplets. We show that these droplets are sensitive to environmental conditions, including temperature, humidity, and ambient flows. Applying the model to a set of idealized conditions such as free-fall and continuous jets, we demonstrate significantly different impacts of environmental parameters on droplets with different sizes. Using a realistic droplet size distribution and cough duration, we quantify the transport and fate of droplets in the near field of source and the potential influences by ambient conditions. The model we developed from this study could be applied to study the mechanisms for airborne pathogens, e.g., influenza virus and new coronavirus.
Virus transmission from urinals
Authors: Wang Ji-Xiang , Li Yun-Yun , Liu Xiang-Dong , Cao Xiang
Published: August 2020

A virus-laden particle movement from urinal flushing is simulated. Similar to the toilet-induced flushing, results indicate that the trajectory of the particles triggered by the urinal flushing manifests an external spread type. Even more alarmingly, the particle can reach 0.84 m (man’s thigh) in 5.5 s when compared with the diffusion performance of the toilet-induced one (around 0.93 m in 35 s). A more violent climbing tendency is discovered in this Letter. Wearing masks should be made mandatory in public washrooms, and anti-diffusion improvements of facilities in public washrooms are urgently needed, especially in the current “SARS-CoV-2” crisis.
Remarkable magnetoelectric effect in single crystals of honeycomb magnet Mn4Nb2O9
Authors: Zheng S. H. , Zhou G. Z. , Li X. , Liu M. F. , Tang Y. S. , Xie Y. L. , Zeng M. , Lin L. , Yan Z. B. , Huang X. K. , Jiang X. P. , Liu J.-M.
Published: August 2020

Linear magnetoelectrics refer to those compounds in which ferroelectric (FE) polarization can be generated by applying the magnetic field. This scenario opens an additional avenue toward high-temperature magnetoelectric (ME) coupling that is achievable in a large class of relatively weak frustrated magnetic systems such as honeycomb antiferromagnets. It is, thus, urgent to unveil the physics underlying the linear ME coupling in these linear ME materials. We grow the single crystals of Mn4Nb2O9, a linear ME candidate with high magnetic ordering temperature, and carry out a set of structural, magnetic, and ME characterizations. An antiferromagnetic ordering with [001]-oriented moments at the Neel point TN = 109 K is identified together with magnetic field driven large electric polarization emerging at TN, due to the strong exchange striction dependent mechanism. The measured ME coupling tensor α fits well the magnetic symmetry −3′m′, consistent with the linear ME scenario. Furthermore, remarkable responses of FE polarization and magnetization to the magnetic field and electric field, respectively, are demonstrated.
Corrigendum to: Modelling suppression difficulty: current and future applications
Authors: Rodríguez y Silva Francisco , O'Connor Christopher D. , Thompson Matthew P. , Molina Martínez Juan Ramón , Calkin David E.
Published: August 2020

Improving decision processes and the informational basis upon which decisions are made in pursuit of safer and more effective fire response have become key priorities of the fire research community. One area of emphasis is bridging the gap between fire researchers and managers through development of application-focused, operationally relevant decision support tools. In this paper we focus on a family of such tools designed to characterise the difficulty of suppression operations by weighing suppression challenges against suppression opportunities. These tools integrate potential fire behaviour, vegetation cover types, topography, road and trail networks, existing fuel breaks and fireline production potential to map the operational effort necessary for fire suppression. We include case studies from two large fires in the USA and Spain to demonstrate model updates and improvements intended to better capture extreme fire behaviour and present results demonstrating successful fire containment where suppression difficulty index (SDI) values were low and containment only after a moderation of fire weather where SDI values were high. A basic aim of this work is reducing the uncertainty and increasing the efficiency of suppression operations through assessment of landscape conditions and incorporation of expert knowledge into planning.
Volcanic controls on seawater sulfate over the past 120 million years
Authors: Laakso Thomas A. , Waldeck Anna , Macdonald Francis A. , Johnston David
Published: August 2020

Significance

A geochemical model shows that discrete volcanic perturbations, coupled to long-term changes in sulfur biogeochemistry result in apparent stepwise changes in the isotopic composition of marine sulfur, similar to the patterns seen in the marine barite record of the Cenozoic and Late Mesozoic. The perturbations required to reproduce this isotope record in the model correlate with the timing and approximate size of large igneous provinces, particularly those intruding volatile-rich rock, suggesting that these events are responsible for much of the enigmatic structure in the sulfur isotope record of the last 120 My.
Cdc48 cofactor Shp1 regulates signal-induced SCF
Met30
disassembly
Authors: Lauinger Linda , Flick Karin , Yen James L. , Mathur Radhika , Kaiser Peter
Published: August 2020

Significance

Ubiquitylation affects many important cellular processes and has been linked to a number of human diseases. It has become a synonym for protein degradation, but ubiquitylation also has important nonproteolytic signaling functions. Understanding the molecular concepts that govern ubiquitin signaling is of great importance for development of diagnostics and therapeutics. The cadmium-induced inactivation of the SCF
Met30
ubiquitin ligase via the disassembly of the multisubunit ligase complex illustrates an example for nonproteolytic signaling pathways. Dissociation is triggered by autoubiquitylation of the F-box protein Met30, which is the recruiting signal for the highly conserved AAA-ATPase Cdc48/p97. Here we show that the UBX cofactor Shp1/p47 is important for this ubiquitin-dependent active remodeling of a multiprotein complex in response to a specific environmental signal.
Membrane-assisted radiant cooling for expanding thermal comfort zones globally without air conditioning
Authors: Teitelbaum Eric , Chen Kian Wee , Aviv Dorit , Bradford Kipp , Ruefenacht Lea , Sheppard Denon , Teitelbaum Megan , Meggers Forrest , Pantelic Jovan , Rysanek Adam
Published: August 2020

Significance

In this paper, we present results from a radiant cooling pavilion, demonstrating a method of cooling people without cooling the air. Instead, surfaces are chilled, and thermal radiation is used to keep people cool. A thermally transparent membrane is used to prevent unwanted air cooling and condensation, a required precursor to deploying radiant cooling panels without humidity control in tropical environments. The results from this thermal-comfort study demonstrate the ability to keep people comfortable with radiation in warm air, a paradigm-shifting approach to thermal comfort that may help curb global cooling-demand projections.
Yeast ATM and ATR kinases use different mechanisms to spread histone H2A phosphorylation around a DNA double-strand break
Authors: Li Kevin , Bronk Gabriel , Kondev Jane , Haber James E.
Published: August 2020

Significance

Creation of a chromosomal double-strand break (DSB) is rapidly accompanied by extensive phosphorylation of yeast histone H2A isoform (H2AX in mammals) by Mec1 (ATR) and Tel1 (ATM) protein kinases. This phosphorylation, termed γ-H2AX, spreads 50 kb on either of the DSB, but how this phosphorylation is propagated is poorly understood. We have monitored the kinetics and extent of spreading individually for Mec1 and Tel1 and find that the patterns of spreading are significantly different for the two kinases. By comparing these experimental data to mathematical models of spreading, either by one-dimensional (1D) or 3D diffusion, we report that Bayesian model selections suggest Tel1 acts by directed motion along a chromatin fiber, whereas Mec1 primarily uses a 3D mode of propagation.
DROOPY LEAF1 controls leaf architecture by orchestrating early brassinosteroid signaling
Authors: Zhao Meicheng , Tang Sha , Zhang Haoshan , He Miaomiao , Liu Jihong , Zhi Hui , Sui Yi , Liu Xiaotong , Jia Guanqing , Zhao Zhiying , Yan Jijun , Zhang Baocai , Zhou Yihua , Chu Jinfang , Wang Xingchun , Zhao Baohua , Tang Wenqiang , Li Jiayang , Wu Chuanyin , Liu Xigang , Diao Xianmin
Published: August 2020

Significance

C
4
cereals in subfamily Panicoideae typically produce large and long leaf blades for efficient capture of light and photosynthesis but the leaves droop downward, particularly at the adult stage, thus, adversely affecting canopy structure and grain yield. Identification of key regulators that control leaf droopiness is crucial to improve plant architecture in these crops. We showed that DPY1, a regulator of SiBRI1–SiBAK1 interaction, prevents BR signaling from overactivation in response to high doses of BRs to ensure that the long leaf blades grow upward in
Setaria
. Overexpressing DPY1 improves plant architecture with upright leaves. This study provides cellular and molecular insights into plant architecture control for cereal breeding.
Indoles from the commensal microbiota act via the AHR and IL-10 to tune the cellular composition of the colonic epithelium during aging
Authors: Powell Domonica N. , Swimm Alyson , Sonowal Robert , Bretin Alexis , Gewirtz Andrew T. , Jones Rheinallt M. , Kalman Daniel
Published: August 2020

Significance

Aging is associated with an increase in baseline inflammation, called inflammaging, that may contribute to frailty in geriatric populations. Inflammaging could result from a decrease in anti-inflammatory mediators, such as IL-10, or a decrease in the capacity of the intestinal barrier to exclude inflammatory antigens. We show that during aging, mice lose goblet cells, which secrete mucus to protect the epithelium. Small molecules related to indole, which are secreted by the intestinal microbiota, act via the aryl hydrocarbon receptor and IL-10 to restore depleted goblet cell numbers in aged animals. Indoles may have utility as therapeutics to protect against or reverse changes in epithelial homeostasis associated with aging and may limit age-associated systemic inflammation, perhaps via induction of IL-10.
Agonist-induced formation of unproductive receptor-G
12
complexes
Authors: Okashah Najeah , Wright Shane C. , Kawakami Kouki , Mathiasen Signe , Zhou Joris , Lu Sumin , Javitch Jonathan A. , Inoue Asuka , Bouvier Michel , Lambert Nevin A.
Published: August 2020

Significance

G protein-coupled receptors (GPCRs) are targeted by a large fraction of approved drugs and regulate many important cellular processes. Association of GPCRs with heterotrimeric G proteins in response to agonist activation is thought to invariably lead to G protein activation. We find instead that G
12
heterotrimers can associate with agonist-bound receptors in a manner that does not lead to activation. These unproductive agonist–receptor-G protein ternary complexes sequester G
12
heterotrimers and thus inhibit rather than support G
12
signaling. These findings reveal a mechanism whereby agonist activation of GPCRs can inhibit as well as promote G protein signaling.
Anacardic acid induces IL-33 and promotes remyelination in CNS
Authors: Ljunggren-Rose Åsa , Natarajan Chandramohan , Matta Pranathi , Pandey Akansha , Upender Isha , Sriram Subramaniam
Published: August 2020

Significance

Many neurological disorders stem from damage to myelin, the insulating material which wraps around nerves and provides optimal nerve conduction. We previously found that IL-33, a chemical made in response to injury, was able to induce new myelin formation. In exploring compounds which can induce IL-33, we found that anacardic acid, a compound found in the plant kingdom, was able to promote the formation of new myelin. In addition, treatment of mice with anacardic acid induced IL-33 in the nervous system and resulted in reduced injury in animal models of disease in which loss of myelin was experimentally induced. We believe that the actions of anacardic acid warrants further study for the treatment of demyelinating diseases.
Nuclear mechanosensing controls MSC osteogenic potential through HDAC epigenetic remodeling
Authors: Killaars Anouk R. , Walker Cierra J. , Anseth Kristi S.
Published: August 2020

Significance

The extracellular matrix is highly dynamic and presents mechanical signals to the residing cells to maintain tissue homeostasis. Recently, the nucleus has been implicated to be a direct mechanosensor, and dysregulation of nuclear mechanosensing might be involved in several diseases, including bone degeneration. To better understand mechanisms behind remodeling of the epigenetic landscape through nuclear mechanosensing, we utilize an innovative photostiffening hydrogel platform to manipulate nuclear mechanosensing in human mesenchymal stem cells. Our results reveal that disruption of nuclear mechanosensing up-regulates histone deacetylases and prevents epigenetic response as well as osteogenic fate determination. Interestingly, we see similar defective nuclear mechanosensing in bone from patients with osteoarthritis, indicating that this cellular mechanism is likely relevant to bone-related diseases.
Single-molecule diffusometry reveals no catalysis-induced diffusion enhancement of alkaline phosphatase as proposed by FCS experiments
Authors: Chen Zhijie , Shaw Alan , Wilson Hugh , Woringer Maxime , Darzacq Xavier , Marqusee Susan , Wang Quan , Bustamante Carlos
Published: August 2020

Significance

Recent experiments have suggested that the energy released by a chemical reaction can propel its enzyme catalyst (for example, alkaline phosphatase). However, this topic remains controversial, partially due to the indirect and ensemble nature of existing measurements. Here, we used recently developed single-molecule approaches to monitor directly the motions of individual proteins in aqueous solution and find that single alkaline phosphatase enzymes do not diffuse faster under catalysis. Instead, we demonstrate that interactions between the fluorescent dye and the enzyme’s substrate can produce the signature of apparent diffusion enhancement in fluorescence correlation spectroscopy, the standard ensemble assay currently used to study enzyme diffusion and indicate that single-molecule approaches provide a more robust means to investigate diffusion at the nanoscale.
Simple binding of protein kinase A prior to phosphorylation allows CFTR anion channels to be opened by nucleotides
Authors: Mihályi Csaba , Iordanov Iordan , Töröcsik Beáta , Csanády László
Published: August 2020

Significance

Ion channels are protein pores that pass ions across biological membranes. CFTR is an anion channel required for proper salt–water transport across epithelia, including the lung and the gut. CFTR overactivation due to bacterial toxins causes severe diarrhea (e.g., in cholera), and impaired activation due to mutations underlies cystic fibrosis, a lethal disease. CFTR is activated by a kinase (PKA) which phosphorylates the channel. Here we show that CFTR activation is not caused by phosphorylation, as believed, but by simple PKA binding which promotes reversible release of CFTR’s regulatory (R) domain from an inhibitory position. Subsequent R-domain phosphorylation renders activation irreversible. Reversible channel activation is likely mediated by several members of a large protein network that interacts with CFTR.
Structural basis for amino acid exchange by a human heteromeric amino acid transporter
Authors: Wu Di , Grund Tamara N. , Welsch Sonja , Mills Deryck J. , Michel Max , Safarian Schara , Michel Hartmut
Published: August 2020

Significance

Amino acids are involved in metabolism, protein biosynthesis, and signal transduction of humans. Heteromeric amino acid transporters maintain homeostasis of amino acid pools in various tissues and organs representing a unique group among members of the solute carrier superfamily. The neutral and basic amino acid transport complex (b
[0,+]
AT1-rBAT) is responsible for reabsorption of cystine and dibasic amino acids in kidney and intestine. Misguided trafficking, incomplete maturation, or defective transport activity result in hyperexcretion of cystine, causing cystinuria. While the function of this amino acid transport complex is known, details of its evolution, biogenesis, and mechanism of action have remained elusive. We determined the cryo-EM structure of this protein complex to gain a deeper understanding of its mode of action.
Integrity of a heterochromatic domain ensured by its boundary elements
Authors: Charlton Sebastian Jespersen , Jørgensen Maria Mønster , Thon Geneviève
Published: August 2020

Significance

The fission yeast silent mating-type region provides an excellent system to ask how chromatic domains with opposite effects on gene expression coexist side by side along chromosomes and to investigate roles played by DNA elements and architectural proteins in the phenomenon. By showing that the
IR-L
and
IR-R
chromatin boundaries favor heterochromatin formation in the domain that separates them, dependent on each other and on binding sites for the architectural factor TFIIIC, our work brings to light an important function of these elements and supports the notion that similar types of interactions between boundaries might in other organisms as well stimulate heterochromatin formation in intervening chromosomal loops to actively shape gene expression landscapes.
A supergene-linked estrogen receptor drives alternative phenotypes in a polymorphic songbird
Authors: Merritt Jennifer R. , Grogan Kathleen E. , Zinzow-Kramer Wendy M. , Sun Dan , Ortlund Eric A. , Yi Soojin V. , Maney Donna L.
Published: August 2020

Significance

The white-throated sparrow, a common North American songbird, is a valuable model in behavioral genetics because of a chromosomal rearrangement that segregates with a behavioral phenotype. Birds with the rearrangement are more aggressive than those without it. Here we show that genetic differentiation of a single gene inside the rearrangement changes how that gene is regulated, driving higher levels of expression in birds with the aggressive phenotype and altering behavior. By experimentally reducing the expression of this one gene, we were able to change the phenotype of the more aggressive birds to the less aggressive phenotype. These results contribute to a greater understanding of how social behaviors can be encoded in the genome and how they evolve.
HARC as an open-shell strategy to bypass oxidative addition in Ullmann–Goldberg couplings
Authors: Lavagnino Marissa N. , Liang Tao , MacMillan David W. C.
Published: August 2020

Significance

Copper-catalyzed carbon–nitrogen bond formation has the potential to provide efficient synthetic access to medicinally relevant organic molecules, but broad use of the coupling has been hampered by the requirement for an energetically challenging substrate activation step (oxidative addition into an aryl halide). Here we report a mechanistic alternative that circumvents oxidative addition by cooperatively employing photochemically generated silicon-centered radicals and copper to activate aryl halides via a one-electron pathway. This dramatically increases the range of accessible products, thereby allowing room-temperature synthesis of a diverse electronic and steric range of products traditionally considered inaccessible via copper catalysis due to the prohibitively high barrier for direct copper oxidative addition.
An enzymatic toolkit for selective proteolysis, detection, and visualization of mucin-domain glycoproteins
Authors: Shon D. Judy , Malaker Stacy A. , Pedram Kayvon , Yang Emily , Krishnan Venkatesh , Dorigo Oliver , Bertozzi Carolyn R.
Published: August 2020

Significance

Researchers and clinicians rely on robust staining methods to detect and visualize biomolecules of interest. Mucins are heavily glycosylated proteins expressed on cells throughout the human body that have historically proved challenging to stain with high specificity, hindering attempts to explore their roles in health and disease. Here, we address this limitation using catalytically inactivated mucin-cleaving bacterial proteases as staining reagents. The differing specificities of these enzymes are retained in their binding properties, enabling a new depth in the analysis of mucins on cells and patient tissues.
Rapid identification and characterization of infected cells in blood during chronic active Epstein-Barr virus infection
Authors: Fournier Benjamin , Boutboul David , Bruneau Julie , Miot Charline , Boulanger Cécile , Malphettes Marion , Pellier Isabelle , Dunogué Bertrand , Terrier Benjamin , Suarez Felipe , Blanche Stéphane , Castelle Martin , Winter Sarah , Delecluse Henri-Jacques , Molina Thierry , Picard Capucine , Ehl Stephan , Moshous Despina , Galicier Lionel , Barlogis Vincent , Fischer Alain , Neven Bénédicte , Latour Sylvain
Published: August 2020

Epstein-Barr virus (EBV) preferentially infects epithelial cells and B lymphocytes and sometimes T and NK lymphocytes. Persistence of EBV-infected cells results in severe lymphoproliferative disorders (LPDs). Diagnosis of EBV-driven T or NK cell LPD and chronic active EBV diseases (CAEBV) is difficult, often requiring biopsies. Herein, we report a flow-FISH cytometry assay that detects cells expressing EBV-encoded small RNAs (EBERs), allowing rapid identification of EBV-infected cells among PBMCs. EBV-infected B, T, and/or NK cells were detectable in various LPD conditions. Diagnosis of CAEBV in 22 patients of Caucasian and African origins was established. All exhibited circulating EBV-infected T and/or NK cells, highlighting that CAEBV is not restricted to native American and Asian populations. Proportions of EBV-infected cells correlated with blood EBV loads. We showed that EBV-infected T cells had an effector memory activated phenotype, whereas EBV-infected B cells expressed plasma cell differentiation markers. Thus, this method achieves accurate and unambiguous diagnoses of different forms of EBV-driven LPD and represents a powerful tool to study their pathophysiological mechanisms.
Cbls boost B cells
Authors: Linterman Michelle A.
Published: August 2020

T cell regulation of antibody-mediated immunity is critical for health. In this issue of JEM, Li et al. (https://doi.org/10.1084/jem.20191537) identify the Cbl family of E3 ubiquitin ligases as B cell–intrinsic gatekeepers of T cell–dependent humoral immunity.
Impacts of revised dose coefficients for the inhalation of NORM-containing dusts encountered in the Western Australian Mining Industry
Authors: Ralph Martin I , Tsurikov Nick , Cattani Marcus
Published: August 2020

The aim of this paper is to evaluate the impact of recent revisions to the dose coefficients published in ICRP-137 and ICRP-141 for members of the 232Th, 238U and 235U decay series on radiation doses received by Western Australian mine workers via the inhalation of insoluble dusts containing long-lived alpha particle emitting radionuclides.

Whilst some dose coefficients for individual members of the decay series have decreased, the nett effect is that the sum of all dose coefficients in all three decay series have increased as a result of the revisions. The increase is inversely related to Activity Median Aerodynamic Diameter.

Assuming the radionuclides in the inhaled dusts are in secular equilibrium, the dose conversion factors (the mean committed effective dose per unit intake of alpha activity) will increase by a factor between 1.9 and 2.9 times.

In 2019, 11 mining operations in Western Australia submitted an annual report of worker radiation exposures to the regulatory authority. The reports indicate that between 35% and 60% of the committed effective doses to workers arises from inhalation of insoluble radioactive dusts. Applying an AMAD of 5 μm and a 232Th decay series to 238+235U decay series ratio of 10:1, committed effective doses to the workforce are greater by a factor of between 0.74 and 1.26 times from those reported in 2018–19 as a result of the revised DCs published in ICRP-137 and ICRP-141.

Guidance on how to calculate doses from the inhalation of radioactive dusts is provided in the regulatory authority’s Guideline ‘NORM-5: Dose Assessment’, which will need revision to incorporate the revised dose coefficients. The Guideline has been widely distributed outside of Western Australia, and those jurisdictions which have adopted all, or sections of it, into their legal framework for radiation protection may need to consider the impact of the revision.
A low cost versatile differential preamplifier for electronic engineering
Authors: De Pinho Ferreira Nicolas , Gehin Claudine , Massot Bertrand
Published: August 2020

Acquisition of differential signals from low voltage and high impedance sources is difficult when using commonly available laboratory test equipment such as a standard oscilloscope or single ended acquisition system. This paper presents a versatile differential preamplifier for universal signal conditioning. The probe offers a wide input voltage range and can measure signals ranging from a few hundred micro-volts up to 100 V with 1 MHz bandwidth. It also contains a programmable output filter for bandwidth limitation and noise reduction, user-accessible controls for offset adjustment and input coupling mode selection. The probe can be powered through an USB port or by using an internal battery. Input impedance can be made virtually infinite by the JFET input stage, which makes this differential preamplifier usable with a variety of high-impedance sources commonly encountered in the sensors research field and in electronic engineering. Experimental validation shows that the proposed device has better performance levels and interoperability than commercially available instrumentation at a reduced cost, even while using off-the-shelf components.
Achieving sub-100 ps time-of-flight resolution in thick LSO positron emission tomography while reducing system cost: a Monte Carlo study
Authors: Walrand Stephan , Hesse Michel , Jamar François
Published: August 2020

Purpose. Evaluating the time-of-flight (TOF) resolution improvement that could be obtained using an easy crystal block modification which enables depth of interaction (DOI) assessment and simplifies the detector assembling process. Method. A fast optical Monte Carlo (MC) code was developed. The code was evaluated versus measurements of the energy resolution, number of detected scintillation photons and TOF resolution (TOFr) reported for different crystal photodetector setups. Then, MC simulations were performed for a modified crystal block section of 8 × 8 mm2 in which two partial saw cuts allow light sharing between four detector pixels with a strong dependence on the DOI. Results. Relative differences between MC simulations and reported measurements were always below 10% for any quantities. The simulations showed that the best TOFr was obtained by leaving the partial saw cuts empty. This feature results from the fact that for a slant angle lower than 56 degrees, the scintillation photons undergo a lossless total reflection at the L[Y]SO → air boundary, which is hardly achievable using a reflector material. According to the simulations, this approach allows a TOFr improvement from 163 ps to 90 ps full width at half-maximum using a 22 mm thick LSO 0.2%Ca:Ce crystal coupled to a FBK-NUV-HD silicon photomultiplier. Conclusion. Sub-100 ps TOFr using thick LSO crystal appears achievable using this simple crystal block modification. The method reduces by a factor of 4 the number of crystal pixels to be covered by a reflective material and afterwards joined together. As clinical positron emission tomography contains about 60 000 crystal pixels, this benefit would reduce the assembling cost.
Phase diagram and optimal control for n-tupling discrete time crystal
Authors: Kuroś Arkadiusz , Mukherjee Rick , Golletz Weronika , Sauvage Frederic , Giergiel Krzysztof , Mintert Florian , Sacha Krzysztof
Published: August 2020

A remarkable consequence of spontaneously breaking the time translational symmetry in a system, is the emergence of time crystals. In periodically driven systems, discrete time crystals (DTC) can be realized which have a periodicity that is n times the driving period. However, all of the experimental observations have been performed for period-doubling and period-tripling DTC. Novel physics can arise by simulating many-body physics in the time domain, which would require a genuine realisation of the n-tupling DTC. A system of ultra-cold bosonic atoms bouncing resonantly on an oscillating mirror is one of the models that can realise large period DTC. The preparation of DTC demands control in creating the initial distribution of the ultra-cold bosonic atoms along with the mirror frequency. In this work, we demonstrate that such DTC is robust against perturbations to the initial distribution of atoms. We show how Bayesian methods can be used to enhance control in the preparation of the initial state as well as to efficiently calculate the phase diagram for such a model. Moreover, we examine the stability of DTCs by analyzing quantum many-body fluctuations and show that they do not reveal signatures of heating.
Research of the influence of hydroabrasive surface cleaning on plasma cutting
Authors: Gabdrakhmanov Az T , Israphilov I H , Shafigullin L N , Gabdrakhmanova T F
Published: August 2020

On the example of plasma cutting of 1.0038 steel, the features of hydroabrasive (EPS) cleaning are shown. The basic requirements for the quality of the cut surface and a wide range of material properties due to the characteristics of the power tool are formulated. The formation of the heat-affected zone, its structure and properties, the formation of macro- and microgeometry of the cut depending on the working gas used are described. The influence of plasma cutting parameters on ensuring the necessary quality and properties of steel is considered.
Experimental installation to study the RF plasma flow at low pressures with experiment data synchronization
Authors: Shemakhin A Yu , Zheltukhin V S , Shemakhin E Yu , Terentev T N , Sofronitsky A O
Published: August 2020

A diagram and description of an experimental setup for studying the properties of a stream of RF plasma at low pressure are presented. The setup is equipped with diagnostic devices that record the temperature, volt-ampere characteristics, and pressure in the chamber.
High-intensity pulsed ion beam treatment of amorphous iron-based metal alloy
Authors: Nazipov R A , Batalov R I , Bayazitov R M , Novikov H A , Shustov V A , Dulov E N
Published: August 2020

The results of intense pulsed ion beam (IPIB) treatment of the soft magnetic amorphous alloy of a FINEMET-type are presented. Foil produced from the alloy was irradiated with short (about 100 ns) pulses of carbon ions and protons with energy of up to 300 keV and an energy density of up to 7 J/cm2. X-ray diffraction, Mössbauer spectroscopy and magnetic measurements were used to investigate structural and magnetic properties of irradiated foils. It is shown that the foil remains intact after the treatment, and the crystal structure still amorphous. Spontaneous magnetization vector is found to lie almost along perpendicular to the foil plane after irradiation, whereas for the initial amorphous foil it belongs to the plane. The magnetic properties of the foil undergo changes: the coercive force decreases, the saturation induction increases slightly, and the magnetization curve has shallower slope.
Particle drift at rotational oscillations of the lower boundary of a rectangular resonator
Authors: Gubaidullin D A , Osipov P P , Nasyrov R R
Published: August 2020

Acoustic streaming generated by standing wave in a rectangular resonator filled with viscous polytropic gas is simulated. Standing wave is excited by rotational vibrations of the lower boundary. The resonator is filled with small particles of water uniformly distributed over its region at the initial moment of time. In this paper the drift of the particles in resonator after a large number of periods studied numerically.
Effect of the speed of the flat substrate movement on the air plasma jet transversal spreading at its impinging the surface
Authors: Akishev Yu S , Balakirev A A , Medvedev M A , Petryakov A V , Trushkin N I
Published: August 2020

Low-temperature plasma jets are used to treat both the motionless and moving objects (targets or substrates). The gas-dynamic aspects of the plasma jet’s interaction with the target are important and have to be taken into account in selecting the most efficient plasma processing parameters. Clearly, the spreading of plasma jet over a fast-moving surface is significantly different from its spreading over a fixed target. This question is investigated by the example of the interaction of an air plasma jet with a surface of fast-rotating dielectric disk. It is shown the change in the shape of the jet striking perpendicularly the moving substrate happens due to the movement of a thin layer of the ambient air adjacent to the fast-moving surface. This effect can have a noticeable influence on the reactive particles transfer from the plasma jet onto the surface to be treated.
Modification of the WC-Co carbide surface with high-intensity pulsed ion beam
Authors: Prima A.I. , Egorova Yu.I. , Pushkarev A.I. , Matryenin S.V.
Published: August 2020

The paper presents the results of WC-Co surface modification with high-intensity pulsed ion beams at high energy density 7-8 J/cm2 per one pulse. One, five and ten pulses regimes of irradiation have been studied using scanning electron microscopy of both the surface morphology and cross-section, X-ray diffraction analysis and a nano-hardness tester. Beam irradiation with high energy density resulted in phase transformation from hexagonal α-WC to cubic ß-WC1-x. XRD analysis shows that the volume content of new formed cubic phase in the modified layer is ~ 97%.
Gas discharge between two liquid electrolyte electrodes
Authors: Tazmeev G K , Tazmeeva R N , Tazmeev B K
Published: August 2020

A gas discharge between two liquid electrolyte electrodes was studied experimentally in the current range of 0.5-3.5 A. As liquid electrolytes, aqueous solutions of sodium chloride, sodium carbonate, potassium hydroxide and copper sulfate, as well as tap water, were used. The effect of composition of electrolytes on characteristics of discharge was studied at different polarities of connection to the power source.
Deformation of porous cylindrical bodies under action on their compressing loads
Authors: Fedyaev V L , Faskhutdinov M Kh
Published: August 2020

The plastic deformation of cylindrical bodies on a rigid base under the action of a flat stamp is considered. It is assumed that the material of these bodies is porous, the loads are unsteady. Friction forces on the contact surfaces of the ends of the cylinder with the stamp and the base are considered small. After a series of simplifying assumptions, the corresponding mathematical problems are formulated. As a result of an analytical solution, they obtained relations for evaluating parameters characterizing the dynamics of compression of bodies, which at the same time make it possible to evaluate the loads acting on the base material, the degree of compaction of it, as well as the material of deformable bodies.
Synthesis of silicon nanowires in electric arc argon plasma
Authors: Timerkaev B A , Feltsinger V S , Shakirov B R
Published: August 2020

This paper presents a method of synthesis of silicon nanowires in microarc argon plasma. During the experiment, an adjustable direct current source with a ballast resistor was used. The cathode was a molybdenum rod, and the anode was silicon. The silicon was located in a small deepening in a graphite rod. During the experiment, synthesis of silicon nanowires was observed on the surface of molybdenum rod. The obtained silicon nanowires are straight and non-hollow inside, nanowires have a smooth surface and have a hexagonal cross-section. The resulting nanowires will be able to find further application in light emitting diodes, lithium-ion batteries, supercapacitors, photovoltaics.
Functional coating preparation based on zinc oxide using low temperature plasma
Authors: Nosov S A , Shinkarev A A , Gorelysheva V E , Savinkov A V
Published: August 2020

The work describes the synthesis of superhydrophobic coating based on zinc oxide with a UV-driven reversible switching between hydrophilic and hydrophobic properties. A coating of vertically oriented acicular crystals of zinc oxide with dimensions of 1-2 μm in length and 50-200 nm in width on a metal substrate was obtained. According to the phase composition and morphology, the crystals correspond to zinc oxide-zincite. The contact angle for the coating after its exposure in a box isolated from daylight for 14 days is 150 °, while for the control metal substrate, the contact angle is 40 °. It is shown that the use of low temperature Ar plasma of low pressure allows changing the surface topography of acicular nanocrystals due to etching of their vertices and edges.
Anomaly detection of power grid dispatching platform based on Isolation Forest and K-means fusion algorithm
Authors: Shouyu Liang , Zhang Kun , Fang Wenchong , Zhou Zhifeng , Hu Rong , Zhu Wen , Li Yingchen , Wang Yichang , Hou Jian
Published: August 2020

It is very important to detect abnormal Access IP of power grid dispatching platform accurately and rapidly to ensure the safety of power production. An Isolation Forest and K-means fusion algorithm is proposed, which not only solves the deficiency of Isolation Forest only being able to detect anomalies in binary classification, but also solves the defect of Isolation Forest threshold setting based on artificial experience or prior assumptions by designing a threshold setting strategy for Isolation Forest anomalies. The Access IP data of the southern power grid dispatching platform is taken as an example to evaluate the proposed algorithm and model. Through control experiments, the effectiveness and advancedness of the algorithm are illustrated in terms of AUC-ROC curve, accuracy, recall, and F1 score.
Optimization and Practice on the Course Content and Teaching Methods of Optoelectronic Testing Technology
Authors: Cui Shaobo , Qin Jiaqiong , Dai Jun
Published: August 2020

The research aimed at the characteristics and teaching requirements of the photoelectric detection technology course, optimized the teaching content and teaching methods of the photoelectric detection technology course, explored how to use scientific research results as the teaching content, and practiced how to put the new teaching method into the course and the teaching process. The practice has shown that the use of scientific research results in teaching is conducive to maintaining the rapid development of high and new technology and a dynamic atmosphere of the times; new teaching methods can improve students’ interest in learning and the quality of teachers’ teaching, and help to cultivate students’ innovative consciousness and ability.
Research on the temperature rise characteristics of power transformers based on fluid-solid-thermal coupling
Authors: Sun C C , Xiao C , Hou J , Yao X L , Ye J , Yu W J , Jiang L
Published: August 2020

The problems of overheating and insulation are the main influencing factors to the operation status of power transformers. Based on the physical model of a 50MVA/110kV oil-immersed self-cooling transformer, the electromagnetic, temperature and fluid field are introduced to establish a three-dimensional temperature rise model of the transformer in this thesis. The loss obtained from the electromagnetic field calculation model is taken as a heat source and input into the transformer temperature rise model. The results show that the hot spot temperature occurs in the core column and increases with the maximum load current when the single-phase ground fault occurs, and the hot spot temperature in the transformer exceeds the limit value. The temperature distribution trends of the core and high and low voltage windings under rated conditions and overload conditions are similar. In addition, the average temperature rise of the windings under overload conditions exceeds the limit value.
Intelligent quality detection system of the transmission tower
Authors: Tian Xiangsheng , Wang Hui , Zhou Kun , Cui Weihua
Published: August 2020

Aiming at the rapid development of the power transmission industry, with the huge number of iron towers and the large amount of tower material quality inspection work, however, the detection efficiency is low. This article analyzed five inspection items, inspection points, and their inspection data volume, which are required for tower material specification inspection, such as parts, galvanized layer, that must be performed in the tower material specification inspection, put forward the plan of tower material quality inspection system integrated by software management system and hardware detection instrument, and designed the system scheme, determined the typical testing equipment with real-time transmission function, and designed the architecture of tower material quality information management system. This system can realize the intelligentization of tower material testing, the digitization of the testing process, and the standardization of testing information management, greatly improving the efficiency and accuracy of tower material quality testing.
Research on Feeder Automation System for Urban Distribution Network
Authors: Huang Yibiao , Li Rong , Wu Linwei , Zhang Junqi , Xiao Zhiming
Published: August 2020

With the development of society, the demand for power supply reliability is also increasing, and the proportion of terminals with feeder automation function in the distribution network is increasing. It has become a research hotspot to find more optimized feeder automation strategy. This paper introduces three kinds of feeder automation schemes: centralized control type, local control type and distributed control type and expounds the fault isolation, non-fault section power supply self-healing strategy in detail. The comparison of several control schemes provides reference for choosing feeder automation scheme according to system architecture.
Research on Online Verification of Relay Protection Setting Value Based on Multi-source Information Fusion Technology and Bow-tie Model
Authors: Xu Yan , Chen Rui
Published: August 2020

In view of the complexity and flexibility of the current power grid, in order to make relay protection online verification more accurate and effective, a protection importance degree sequence assessment method based on the multi-source information fusion technology and bowtie model is proposed. Firstly, the cause of incorrect protection actions is analyzed by establishing a fault tree through multi-source information fusion technology, and the event tree analysis method is used to deduce the final development result of the event. Combined with the fault tree and the event tree, a bow-tie model is formed to visually and completely describe the whole process of the event. Then the economic loss of the event is analyzed as the basis for assessing the protection importance degree, and the online inspection of the protection setting value is completed from high to low according to the importance degree sequence. Finally, the IEEE 3-machine 9-bus system is used to verify the correctness and rationality of the method through simulation.
Research on Practice Teaching and Reform of RF Circuit Course
Authors: Cai Wanxiong
Published: August 2020

In the context of the era of high-correction transition to applied technology, as a highly applicable RF circuit course, students should continue to strengthen their practical ability. The traditional talent training model that emphasizes theory over practice is difficult to meet the actual needs of enterprises. Real cases and real training for job positions and practical work tasks are practical ways of reforming practical teaching. They are of great significance for improving students’ learning ability, combining theory and practice, and achieving seamless connection between talent training and corporate needs.
Test Analysis and Simulation Calculation of Temperature Field for Dry-Type Air-Core Reactor
Authors: Wu Jianling , Ou Zhonghua , Huo Feng
Published: August 2020

Based on test analysis and simulation calculation of temperature field for dry-type air-core reactor, the temperature rise rule of internal axial dimension and enveloping internal conductor were analyzed. The highest temperature rise point in the envelope is located about 1/4 of the packet seal. The temperature rise difference between the inner wires is small, and the temperature rise difference within the envelope is less than 1 °C. The radial distribution of temperature along the insulating impregnated glass fiber has a great gradient. The temperature in the middle of the airway is near room temperature, and the temperature rise is about 5K, and the internal temperature of the airway has a larger gradient. For airway width design, the influence of the change of the airway width of the temperature rise distribution should be considered.
A simulation study of argon discharge in PIG ion source with axial magnetic field
Authors: Li Jie , Ju Shaojia , Yue Aizhong , Zhang Xiaolei , Wang Hu , Lu Jie , Zhou Xiaohua
Published: August 2020

In this study, we used a two-dimensional fluid model to investigate the argon discharge in Penning ion gauge (PIG) ion source influenced by magnetic field and the structure of ion source. Under fixed anode voltage U and pressure P, the relationships between the axial magnetic field, the structure parameter K, which is the ratio of the distance of two cathodes and the diameter of the anode tube, and the electron density are obtained. For fixed magnetic field B=0.01 T and pressure P=0.5 Torr, the electron density along the central axis has the maximal value when K=0.8. With fixed K=0.8 and P=1 Torr, the maximal electron density was found when B=0.1 T. Our results imply that there are optimal values for magnetic field and K which induce the maximal plasma density.