bluuebunny/crossref_metadata_2025 huggingface dataset:
Difference of Eu3+ luminescent properties in YOCl and YOBr oxyhalide hosts
Authors: Kitagawa Yuuki , Ueda Jumpei , Arai Kazunari , Kageyama Hiroshi , Tanabe Setsuhisa
Published: May 2021

The photoluminescence spectra and luminescence lifetimes of Eu3+-doped oxyhalides, YOX:Eu3+ (X = Cl or Br), and their temperature dependence on different halide species of mixed-anion coordinations were investigated and analyzed. In terms of the ionic and covalent nature of bonding, Eu3+ ions form different coordination polyhedra in the isostructural YOCl and YOBr hosts: a ninefold [Eu3+O4Cl5] and an eightfold [Eu3+O4Br4] polyhedra. The Judd–Ofelt Ω2 parameter for YOCl:Eu3+ takes a very large value (=8.81 × 10−20 cm2) due to the ninefold polyhedron with C4v symmetry. On the other hand, despite the same C4v symmetry, YOBr:Eu3+ shows a very small Ω2 parameter (=2.72 × 10−20 cm2) because of its structural similarity to the square antiprism polyhedron with D4 symmetry. The Ω4 parameters for YOX:Eu3+ are much larger than those for other Eu3+-doped oxides, possibly related to the covalency of halide anions, Cl− and Br−, showing an intense luminescence band (5D0 → 7F4) at around 700 nm. The Eu3+ ions in these YOX hosts were excitable by charge transfer bands in 270–280 nm regions. The relaxation pathways from the charge transfer states to the initial states for luminescence are discussed, using the configuration coordinate diagrams with the spectroscopic characterization.
Quasi-maser operation using magnetic tunnel junctions
Authors: Yamada Yuma , Goto Minori , Yamane Takekazu , Degawa Naomichi , Suzuki Tsuyoshi , Shimura Atsushi , Aoki Susumu , Mizuno Tomohito , Urabe Junichiro , Hara Shinji , Miwa Shinji , Suzuki Yoshishige
Published: May 2021

Quasi-maser operations using magnetic tunnel junctions (MTJs) that amplified the transmission of radio frequency (RF) signals through themselves are demonstrated. We measured the transmittance of heat-driven MTJs using a vector network analyzer and observed that transmittance S21 >1 at sub-GHz frequencies. Furthermore, we installed two of these MTJs in a feedback-loop circuit and investigated the RF signal in the circuit. The results showed that the auto-oscillation mode of the RF signal appeared without phase synchronization of each MTJ because of the amplification effect. Our results will help develop a mechanism for producing coherent microwave signals using multiple MTJs.
Inertia-enhancement effect of divergent flow on the force characteristics of a Bernoulli gripper
Authors: Yu Xubo , Li Xin
Published: May 2021

Bernoulli grippers, which are widely employed in automated production lines, are pneumatic manipulators capable of noncontact adsorption that utilize the decelerating inertial effect of the radial air flow to generate negative pressure and a suction force. This paper proposes an innovative design for the Bernoulli grippers in which divergent flow is formed through a tiny-inclination cone structure between the gripper and the workpiece, and the inertia-enhancement effect of the divergent flow is exploited to greatly increase the negative pressure and suction force (hereafter, this is referred to as a divergent-flow gripper). First, a theoretical model of the divergent flow between the divergent-flow gripper and the workpiece was formulated. The theoretical formulas for calculating the pressure distribution and suction force were then derived. Suction force measurement experiments were then conducted, whose results indicated that the proposed divergent-flow gripper can increase the suction force by several factors compared with that of an unmodified gripper with a flat surface. The influence of the divergent flow on the inertial and viscous effects of the gripper was examined both theoretically and experimentally, and the main factors leading to the increase in suction force were analyzed. In addition, this paper discusses the influence of the inclination angle and diameter of the gripper. As a result, through changes in the geometric structure and velocity distribution, the proposed divergent-flow gripper has the advantages of a large suction force and simple structure, and these findings serve as important theoretical and experimental references for the design of the Bernoulli gripper.
Influence of atmospheric stability on wind-turbine wakes with a certain hub-height turbulence intensity
Authors: Du Bowen , Ge Mingwei , Zeng Chongji , Cui Guixiang , Liu Yongqian
Published: May 2021

Atmospheric stability can significantly influence the spreading of wind-turbine wakes. The previous studies often coupled atmospheric stability with the turbulence intensity and attributed the influence of atmospheric stability to the enhancement or suppression of turbulence due to the buoyancy effect. In this study, we decouple atmospheric stability with the ambient turbulence intensity, and the pure influence of atmospheric stability on the turbine wakes is investigated at a certain hub-height turbulence intensity via large-eddy simulation. We find that the spanwise turbulence transport plays a crucial role in wake recovery, and atmospheric stability influences this transport by redistributing the turbulence intensity between the three components and altering the spatial scales of the atmospheric motion. Under the convection condition, the spanwise turbulence intensity is greatly enhanced with enlarged flow scales. Hence, more Reynolds shear stress is generated under the shear effect between the ambient flow and the wake flow, which thus enhances spanwise turbulence transport, resulting in a faster recovery of turbine wakes. While for the stable condition, although the spanwise turbulence intensity is slightly enhanced, the flow scales are obviously reduced, resulting in a decrease in wake meandering, which leads to a decrease in turbulence transport in the wake region and a slower recovery of wind-turbine wakes.
CompoNet with SFEL: A convolutional neural network for identifying low-emissivity coating damage
Authors: Wu Xin , Xu Haojun , Wei Xiaolong , Li Yiwen , Pei Binbin , Li Caizhi , Hua Weizhuo , He Weifeng
Published: May 2021

The use of low-emissivity coatings as an infrared (IR) stealth method for weaponry is an important guarantee for the survival of weaponry in the battlefield. The damage on low-emissivity coatings leads to a significant drop in the IR stealth performance of weaponry. Therefore, this paper carries out a research on the intelligent damage identification of low-emissivity coatings based on convolutional neural networks (CNNs). A low-emissivity coating damage dataset with the characteristics of large changes in brightness, distortion of images, and large changes in the target scale is constructed. A composite network (CompoNet) based on feature fusion is designed to extract the detailed features of damage and identify damage types. Compared with VGG16, the damage identification accuracy of CompoNet is improved by 5.49% points. The idea of specific feature extraction layers (SFELs) is proposed. Three SFELs are designed to extract the color, texture, and contour features, which are important basis for judging damage types. The SFEL accelerates the convergence of the model and increases the identification accuracy of the model by 2.02% points. The generative adversarial network is used to generate low-emissivity coating damage images, which solves the problem that the number of damage images collected is small due to practical difficulties. The final damage identification accuracy of the CompoNet fused with SFELs (CompoNet with SFELs) constructed in this paper reaches 99.17%, which is much higher than other generic CNNs.
Influence of enhanced low dose rate sensitivity on single-event transient degradation in the LM158 bipolar operational amplifier
Authors: Xiang Chuanfeng , Yao Shuai , Lu Wu , Li Xiaolong , Yu Xin , Wang Xin , Liu Mohan , Sun Jing , Guo Qi
Published: May 2021

The synergistic effect of enhanced low dose rate sensitivity and single-event transients (SETs) in the bipolar dual operational amplifier LM158 is studied. The test results show a significant reduction in the SET amplitude and broadening in the SET waveform upon exposure to total ionizing dose radiation. These results are much more prominent for a low dose rate (LDR) irradiation of 0.01 rad(Si)/s than for a high dose rate irradiation of 10 rad(Si)/s. The greater gain degradation in the LM158 with LDR irradiation could be the direct cause of the reduction in the SET amplitude and broadening in the SET waveform, and this is corroborated through HSPICE simulations.
Maintenance energy requirement and efficiency of utilisation of metabolisable energy for milk production of
Authors: Kelly L. , Bougouin A. , Kebreab E.
Published: May 2021

Context Dairy consumption has the ability to provide nutrient dense food in low-income countries. However, cows in the tropics may not be able to reach their full potential due to poor nutrition. In tropical regions, milk is mostly produced by Bos taurus × Bos indicus crossbred cattle for which no nutrient requirement tables have been fully developed. Although many novel feeds and feed additives have been tested, nutrient requirements specifically targeting energy and protein for these livestock need to be estimated accurately for milk production to increase sustainably. Aims To determine the net energy for lactation (NEL) requirement for maintenance and efficiency of utilisation of metabolisable energy intake (MEI) for milk production (kL) of Bos taurus × Bos indicus crossbred dairy cows in the tropics. Methods A meta-analysis using 141 observations from 38 independent studies in tropical regions with crossbred dairy cows was conducted. The energy produced in milk corrected for zero energy balance (EL0) was regressed by MEI including other covariates. This meta-regression analysis was conducted by frequentist inference via optimisation in RStan. Key results The best-fit model contained only MEI as a covariate. This model predicted a net energy for lactation value at maintenance of 0.323 MJ/kg BW0.75.day (s.e. = 0.0004) with variations for each specific study. The efficiency with which MEI is used for milk production was estimated to be 0.554 (s.e. = 0.00008), which was common for all studies. Conclusion The key energy parameters estimated in this study should replace commonly used values derived from Bos taurus breeds when formulating diets for crossbred tropical cattle. Implications Nutritional requirement tables need to be estimated specifically for Bos taurus × Bos indicus crossbred dairy cows as their requirements differ from Western breeds. Using appropriate nutritional requirements of crossbred cattle would lead to better nutrition and increased production as determined by their genetic merit.
Selection for lower residual feed intake in mice is accompanied by increased body fatness and lower activity but not lower metabolic rate
Authors: Hebart M. L. , Herd R. M. , Oddy V. H. , Geiser F. , Pitchford W. S.
Published: May 2021

Context Mice bred to be genetically different in feed efficiency were used in this experiment designed to help improve our knowledge of the biological basis of variation in feed efficiency between individual animals. Aims This experiment used mice to explore the metabolic basis of genetic variation in feed efficiency in the growing animal. Methods Mice bred to differ in residual feed intake (RFI) recorded over a postweaning test were used. After 11 generations of divergent selection, mice in groups were tested for RFI from 6 to 8, 8 to 10, and 10 to 12 weeks of age, and measured for traits describing the ability to digest feed, body composition, protein turnover, basal and resting metabolic rate, and level of activity. Key results Compared with the low-RFI (high efficiency) line mice, high-RFI mice consumed 28% more feed per day over their RFI-test, were no heavier, were leaner (16% less total fat per unit of bodyweight), did not differ in the fractional synthesis rate of protein in skeletal muscle or in liver, and had similar basal metabolic rates at 33°C. On an energy basis, the selection lines did not differ in energy retained in body tissue gain, which represented only 1.8% of metabolisable energy intake. The remaining 98.2% was lost as heat. Of the processes measured contributing to the higher feed intake by the high-RFI mice, 47% of the extra feed consumed was lost in faeces and urine, activity was 84% higher and accounted for 24%, the cost of protein gain was 6% higher and accounted for 2%, and the energy cost of digesting and absorbing the extra feed consumed and basal heat production could have accounted for 11 and 15% each. Conclusions Selection for low RFI (high efficiency) in mice was accompanied by an increase in body fat, an improvement in the process of digestion, a lower rate of protein turnover and a much lower level of activity. Selection did not result in major change in basal metabolic rate. Implications This experiment with mice provided new information on the biological basis of genetic differences in feed efficiency. The experiment investigated the relative importance of major energy-consuming metabolic processes and was able to quantify the responses in protein turnover and level of activity, being responses in energy-consuming processes that have proven difficult to quantitatively demonstrate in large farm animals.
The Future of Retrosynthesis and Synthetic Planning: Algorithmic, Humanistic or the Interplay?
Authors: Williams Craig M. , Dallaston Madeleine A.
Published: May 2021

The practice of deploying and teaching retrosynthesis is on the cusp of considerable change, which in turn forces practitioners and educators to contemplate whether this impending change will advance or erode the efficiency and elegance of organic synthesis in the future. A short treatise is presented herein that covers the concept of retrosynthesis, along with exemplified methods and theories, and an attempt to comprehend the impact of artificial intelligence in an era when freely and commercially available retrosynthetic and forward synthesis planning programs are increasingly prevalent. Will the computer ever compete with human retrosynthetic design and the art of organic synthesis?
LED spectral quality and NaCl salinity interact to affect growth, photosynthesis and phytochemical production of
Authors: He Jie , Koh Dominic J. Q. , Qin Lin
Published: May 2021

The edible halophyte Mesembryanthemum crystallinum L. was grown at different NaCl salinities under different combined red and blue light-emitting diode (LED) light treatments. High salinity (500 mM NaCl) decreased biomass, leaf growth, and leaf water content. Interactions between LED ratio and salinity were detected for shoot biomass and leaf growth. All plants had Fv/Fm ratios close to 0.8 in dark-adapted leaves, suggesting that they were all healthy with similar maximal efficiency of PSII photochemistry. However, measured under the actinic light near or above the growth light, the electron transport rate (ETR) and photochemical quenching (qP) of M. crystallinum grown at 100 and 250 mM NaCl were higher than at 500 mM NaCl. Grown under red/blue LED ratios of 0.9, M. crystallinum had higher ETR and qP across all salinities indicating higher light energy utilisation. Crassulacean acid metabolism (CAM) was induced in M. crystallinum grown at 500 mM NaCl. CAM-induced leaves had much higher non-photochemical quenching (NPQ), suggesting that NPQ can be used to estimate CAM induction. M. crystallinum grown at 250 and 500 mM NaCl had higher total chlorophyll and carotenoids contents than at 100 mM NaCl. Proline, total soluble sugar, ascorbic acid, and total phenolic compounds were higher in plants at 250 and 500 mM NaCl compared with those at 100 mM NaCl. An interaction between LED ratio and salinity was detected for proline content. Findings of this study suggest that both salinity and light quality affect productivity, photosynthetic light use efficiency, and proline accumulation of M. crystallinum.
Rodenticide baiting black rats (
Authors: Ringler David , Guillerault Nicolas , Baumann Mickaël , Cagnato Martin , Russell James C.
Published: May 2021

Context Mangroves and intertidal habitats have been identified as particularly challenging environments for bait application within both tropical and temperate environments, because bait applied to areas that are tidally inundated could degrade rapidly or become inaccessible to rats. Aims To determine rat density, ranging behaviour and probability of detection using different monitoring devices; additionally, to determine the availability (persistence, durability and uptake) of rodenticide baits within tidally inundated mangrove habitats. Methods The population biology of black rats (Rattus rattus) was studied in two contrasting mangrove habitats on Europa Island, and spatially explicit mark–recapture studies were performed to estimate densities and activity of rats. A series of bait availability trials was conducted to determine the durability of rodenticide baits on the ground and uptake in the canopy (‘bait bolas’). Key results Black rats were found to be abundant in mangrove, and despite daily tidal inundation, still maintained ranging behaviour consistent with rats in adjacent terrestrial habitats. Larger rodenticide bait blocks remained within tidally inundated habitat throughout tidal cycles and were available and remained palatable to rats for at least three consecutive nights, although strong bait competition occurred with crabs. Bait bolas were available in mangrove canopy exclusively to rats and consumption commenced on the first night. Conclusions The results provide evidence that mangrove habitats are an important habitat for rats, but the biology of rats in these habitats does not meaningfully differ from adjacent terrestrial habitats. With the use of larger rodenticide blocks, tidal inundation does not affect bait availability, but crabs remain a major competitor for these baits. Alternatively, the present study revealed that bait bolas limit bait access to rats alone. Development as an aerial eradication technology should be also recommended. Implications These results provide a proof of concept that eradication of rats from tidally inundated habitats such as mangrove should be possible with only small modifications to current best practice.
Discovering unknown human and mouse transcription factor binding sites and their characteristics from ChIP-seq data
Authors: Yu Chun-Ping , Kuo Chen-Hao , Nelson Chase W. , Chen Chi-An , Soh Zhi Thong , Lin Jinn-Jy , Hsiao Ru-Xiu , Chang Chih-Yao , Li Wen-Hsiung
Published: May 2021

Significance

Transcription factor binding sites (TFBSs) are essential for gene regulation, but the majority of TFBSs remain unknown. To discover new TFBSs, we developed a computational pipeline to analyze human and mouse ChIP-seq (chromatin immunoprecipitation followed by sequencing) data. We found that the number of motif occurrences in ChIP-seq peaks is a highly effective quality-control criterion. Analyzing 1,089 human (101 mouse) TF experiments, we inferred 2,058 (163) motifs, including 487 previously unreported motifs, revealing predicted TFBS enrichment in promoters, particularly near transcription start sites. However, some TFs have TFBSs enriched in intergenic regions, including enhancers. We found frequent interactions between TFs, with a higher frequency of tethered binding than cobinding. This study provides many previously unreported TFBSs and describes their biological features.
Structure elucidation of the elusive Enzyme I monomer reveals the molecular mechanisms linking oligomerization and enzymatic activity
Authors: Nguyen Trang T. , Ghirlando Rodolfo , Roche Julien , Venditti Vincenzo
Published: May 2021

Significance

Enzyme I (EI) is a central player in bacterial metabolism that controls carbon uptake, virulence, and biofilm formation of bacterial cells. Conserved in gram-positive and gram-negative bacteria but absent in eukaryotes, EI is a promising target for antimicrobial design. EI’s monomer–dimer equilibrium plays a crucial role in regulating enzymatic activity, yet very little is known about the changes in structure, dynamics, and substrate-binding properties undergone upon dimerization. Using a combination of protein engineering and pressure perturbation, we isolated EI’s monomeric state and characterized its structure in solution by NMR spectroscopy. Our study provides an atomic-level description of the structural changes accompanying EI dimerization and opens perspectives for the design of allosteric inhibitors.
Colloidal transport and flocculation are the cause of the hyperenrichment of gold in nature
Authors: McLeish Duncan F. , Williams-Jones Anthony E. , Vasyukova Olga V. , Clark James R. , Board Warwick S.
Published: May 2021

Significance

Hydrothermal veins supply much of the Earth’s gold. Their propensity to contain “bonanza” occurrences of gold that have concentrations millions of times greater than the concentration of gold in Earth’s crust makes them important targets for exploration and resource development. The mechanisms by which such hyperenrichment occurs are enigmatic. The accepted wisdom is that this enrichment reflects the saturation and precipitation of gold from hydrothermal fluids. Laboratory experiments and measurements of active hydrothermal systems, however, have shown that the solubility of this noble metal is exceptionally low. Here, we demonstrate that this issue is resolved by the physical transport of gold in the solid state as nanoparticles and their flocculated aggregates, thereby explaining the paradox of bonanza gold ore formation.
Atomic-scale insights into quantum-order parameters in bismuth-doped iron garnet
Authors: Xu Kun , Zhang Luo , Godfrey Andy , Song Dongsheng , Si Wenlong , Zhao Yawen , Liu Yi , Rao Yiheng , Zhang Huaiwu , Zhou Heng-An , Jiang Wanjun , Wang Wenbin , Cheng Zhiying , Zhu Jing
Published: May 2021

Significance

Substituted iron garnets, with a complex and diverse range of substitutional lattice sites, are widely used in magneto-optical devices. Atomic-scale investigations of local variations due to such substituents can give insights into the specific effects of elemental substitution, thereby helping to improve the functionality of magneto-optical materials. Here, via advanced electron microscopy techniques and theoretical calculations, we reveal how variations in the microstructure of Bi-substituted lutetium iron garnet are coupled to modulations in the lattice, electron, and spin structure. Our comprehensive approach provides a template for further improvement of materials through compositional design and shows how cooperative measurement of correlation characteristics between multiple quantum order parameters at the atomic scale can be beneficial for a wide range of functional materials.
Evolution of mechanical cooperativity among myosin II motors
Authors: Wagoner Jason A. , Dill Ken A.
Published: May 2021

Significance

Myosin II is a molecular motor that generates force and motion in muscle cells. During muscle contraction, many myosin II motors bind to the same actin filament, like people pulling on a rope in a tug-of-war. We study how myosin II motors have evolved to coordinate their actions. We find that a key property of muscle performance is how far a filament slides backward when a motor at the end of its cycle releases. This backsliding is not a property of an individual motor; it depends on the entire multimotor system. We find evidence that myosin II has evolved to minimize this backsliding. These evolutionary trends also explain differences in speed and efficiency observed in muscle tissues across different species.
Genetically edited CD34
+
cells derived from human iPS cells in vivo but not in vitro engraft and differentiate into HIV-resistant cells
Authors: Morvan Maelig G. , Teque Fernando , Ye Lin , Moreno Mary E. , Wang Jiaming , VandenBerg Scott , Stoddart Cheryl A. , Kan Yuet Wai , Levy Jay A.
Published: May 2021

Significance

Our study demonstrates that CD34
+
cells generated from human induced pluripotent stem cells (iPSCs) genetically engineered to confer resistance to HIV have engraftment capabilities if they are derived in vivo but not in vitro. We used iPSCs from HIV-infected patients under antiretroviral therapy to form teratomas in immunodeficient mice and isolated CD34
+
cells from these teratomas. We showed not only that these CD34
+
cells could engraft in recipient mice but also that their cell progeny found in the mouse peripheral blood was resistant to HIV infection. These findings confirm the potential for evaluating in an animal model the clinical development of cure therapies using genetically modified autologous iPSCs from patients with HIV.
Cbl-b deficiency prevents functional but not phenotypic T cell anergy
Authors: Nguyen Trang T.T. , Wang Zhi-En , Shen Lin , Schroeder Andrew , Eckalbar Walter , Weiss Arthur
Published: May 2021

T cell anergy is an important peripheral tolerance mechanism. We studied how T cell anergy is established using an anergy model in which the Zap70 hypermorphic mutant W131A is coexpressed with the OTII TCR transgene (W131AOTII). Anergy was established in the periphery, not in the thymus. Contrary to enriched tolerance gene signatures and impaired TCR signaling in mature peripheral CD4 T cells, CD4SP thymocytes exhibited normal TCR signaling in W131AOTII mice. Importantly, the maintenance of T cell anergy in W131AOTII mice required antigen presentation via MHC-II. We investigated the functional importance of the inhibitory receptor PD-1 and the E3 ubiquitin ligases Cbl-b and Grail in this model. Deletion of each did not affect expression of phenotypic markers of anergic T cells or T reg numbers. However, deletion of Cbl-b, but not Grail or PD-1, in W131AOTII mice restored T cell responsiveness and signaling. Thus, Cbl-b plays an essential role in the establishment and/or maintenance of unresponsiveness in T cell anergy.
A review on nanostructured thin films on flexible substrates: links between strains and magnetic properties
Authors: Zighem F , Faurie D
Published: May 2021

This paper provides a topical review of work on systems based on magnetic nanostructured thin films on polymer substrates. This topic has indeed experienced a significant growth in the last ten years. Several studies show a strong potential of these systems for a number of applications requiring functionalities on non-planar surfaces. However, the deformations necessary for this type of applications are likely to modify their magnetic properties, and the relationships between strain fields, potential damages and functional properties must be well understood. This review focuses both on the development of techniques dedicated to this research, on the synthesis of the experimental results obtained over the last ten years and on the perspectives related to stretchable or flexible magnetoelectric systems. In particular, the article focuses on the links between magnetic behavior and the strain field developing during the whole history of these systems (elaboration, reversible and irreversible loading).
Bearing fault diagnosis based on optimized variational mode decomposition and 1D convolutional neural networks
Authors: Wang Qinghua , Yang Chenguang , Wan Hongqiang , Deng Donghua , Nandi Asoke K
Published: May 2021

Due to the fact that measured vibration signals from a bearing are complex and non-stationary in nature, and that impulse characteristics are always immersed in stochastic noise, it is usually difficult to diagnose fault symptoms manually. A novel hybrid fault diagnosis approach is developed for denoising signals and fault classification in this work, which combines successfully variational mode decomposition (VMD) and a one-dimensional convolutional neural network (1D CNN). VMD is utilized to remove stochastic noise in the raw signal and to enhance the corresponding characteristics. Since the modal number and penalty parameter are very important in VMD, a particle swarm mutation optimization as a novel optimization method and the weighted signal difference average as a new fitness function are proposed to optimize the parameters of VMD. The reconstructed signals of mode components decomposed by optimized VMD are used as the input of the 1D CNN to obtain fault diagnosis models. The performance of the proposed hybrid approach has been evaluated using sets of experimental data on rolling bearings. The experimental results demonstrate that the VMD can eliminate signal noise and strengthen status characteristics, and the proposed hybrid approach has a superior capability for fault diagnosis from vibration signals of bearings.
Multi-colour light emission from InGaN nanowires monolithically grown on Si substrate by MBE
Authors: Gridchin Vladislav O , Kotlyar Konstantin P , Reznik Rodion R , Dragunova Anna S , Kryzhanovskaya Natalia V , Lendyashova Vera V , Kirilenko Demid A , Soshnikov Ilya P , Shevchuk Dmitrii S , Cirlin George G
Published: May 2021

InGaN nanostructures are among the most promising candidates for visible solid-state lighting and renewable energy sources. To date, there is still a lack of information about the influence of the growth conditions on the physical properties of these nanostructures. Here, we extend the study of InGaN nanowires growth directly on Si substrates by plasma-assisted molecular beam epitaxy. The results of the study showed that under appropriate growth conditions a change in the growth temperature of just 10 °C leads to a significant change in the structural and optical properties of the nanowires. InGaN nanowires with the areas containing 4%–10% of In with increasing tendency towards the top are formed at the growth temperature of 665 °C, while at the growth temperatures range of 655 °C–660 °C the spontaneously core–shell NWs are typically presented. In the latter case, the In contents in the core and the shell are about an order of magnitude different (e.g. 35% and 4% for 655 °C, respectively). The photoluminescence study of the NWs demonstrates a shift in the spectra from blue to orange in accordance with an increase of In content. Based on these results, a novel approach to the monolithic growth of In
x
Ga1−x
N NWs with multi-colour light emission on Si substrates by setting a temperature gradient over the substrate surface is proposed.
Frictional characteristics of graphene layers with embedded nanopores
Authors: Tong Mingjie , Jiang Yan , Wang Liya , Wang Chengyuan , Tang Chun
Published: May 2021

Graphite possessing extraordinary frictional properties has been widely used as solid lubricants. Interesting frictional characteristics have been observed for pristine graphene layers, for defective graphene, the frictional signal shows richer behaviors such as those found in topological defective graphene and graphene step edges. Recently discovered nanoporous graphene represents a new category of defect in graphene and its impact on graphene frictional properties has not yet been explored. In this work, we perform molecular dynamics simulations on the frictional responses of nanoporous graphene layers when slid using a silicon tip. We show that the buried nanopore raises maximum friction signal amplitude while preserving the stick-slip character, the size of the nanopore plays a key role in determining the maximum frictional force. Negative friction is observed when the silicon tip scanned towards the center of the nanopore, this phenomenon originates from the asymmetrical variation of the in-plane strain and the out-of-plane deformation when indented by the silicon tip. Moreover, the layer dependent frictional character is examined for the buried graphene nanopores, showing that increasing graphene layers weakens the effect of nanopore on the frictional signal.
Supersymmetry with self-consistent Schrödinger–Poisson equations: finding partner potentials and breaking symmetry
Authors: Abouzaid Amine , Levi A F J
Published: May 2021

It is shown that isospectral Hamiltonians and partner potentials can be found for self-consistent solutions of the Schrödinger and Poisson equations in the presence of identical non-interacting electrons. Perturbation of these systems by an external electric field can be used to break symmetry and spectrally distinguish between states. For a given pair of partner potentials, symmetry may also be broken by a change of electron density or temperature.
Gravitational waves from type II axion-like curvaton model and its implication for NANOGrav result
Authors: Kawasaki Masahiro , Nakatsuka Hiromasa
Published: May 2021

The recent report of NANOGrav is gathering attention since its signal can be explained by a stochastic background of gravitational waves (GWs) with an abundance of ΩGW ∼ 10-9 at the reference frequency f ∼ 10-8.
The PBH formation scenario is one of the candidates for the NANOGrav signal, which can simultaneously explain the observed 30M☉ black holes in the binary merger events in LIGO-Virgo collaboration.
We focus on the type-II axion-like curvaton model of the PBH formation.
In the type II model, the complex field whose phase part is the axion rolls down from the origin of the potential.
It is found that type II model achieves the broad power spectrum of the density perturbations and can simultaneously explain the LIGO-Virgo events and the NANOGrav signal.
We also improve the treatment of the non-Gaussianity of perturbations in our model to accurately estimate the amplitude of the induced GWs.
Recent results from EDELWEISS Dark Matter searches
Authors: Gascon J.
Published: May 2021

The EDELWEISS collaboration is performing direct searches for light Dark Matter particles using cryogenic germanium detectors equipped with a charge and thermal signal readout. This versatile and highly performing technology opens new possibilities for searches for signals involving either electrons or nuclear recoils. This is attested to by results on Axion- Like Particles in the keV range, and by the attainment of the first sub-GeV spin-independent dark matter limit based on a germanium target. The search has been extended to Strongly Interacting Particles (SIMP) down to 45 MeV by exploiting the Migdal effect. New results on SIMPs with spin-dependent interactions will also be presented.
Dark Matter Search Results from DAMIC
Authors: Chavarria A.E.
Published: May 2021

We present the current status of DAMIC at SNOLAB: a search for low-mass dark matter (DM) particles with low-noise CCDs. A 40 g 7-CCD array started operation in February 2017 and DM search data was acquired throughout 2017–2019. We summarize recent results on the search for few-e
− ionization signals induced by electronic recoils from the scattering of DM particles with masses ˜MeVc
−2 or the absorption of hidden photons with masses 1–10 eV c
−2. We report on the status of the search for ionization signals greater than 15 e
− from recoiling silicon nuclei following the scattering of DM particles with masses ˜GeV c
−2.
Search for WIMP-129Xe inelastic scattering using particle identification in the XMASS experiment
Authors: Suzuki Takumi
Published: May 2021

The inelastic scattering of Weakly Interacting Massive Particles (WIMPs) and 129Xe nuclei was searched for in the XMASS experiment. When excited by the inelastic scattering, the nuclei emit 39.6 keV γ-ray. The exposure of the data was 327 kg × 800.0 days. To improve the sensitivity of the signal, the events were classified by their pulse shapes, which discriminates between γ-rays and β-rays. As no significant signal was found, the upper limits of the inelastic channel cross section at the 90% confidence level were set. For a 200 GeV/c
2 WIMP, the limit was 4.1 × 10−39 cm2. This is the most stringent limit of the SD WIMP-neutron interaction.
Search for charged excitations of dark matter by KamLAND-Zen experiment
Authors: Hosokawa Keishi
Published: May 2021

There are many scenarios in which dark matter is a part of a multiplet with an electrically charged state. If WIMP dark matter is accompanied by a charged state separated by a small mass difference, it can form stable bound states with nuclei. The region of observable energy deposition via this process of bound state formation is O(1˜10 MeV). KamLAND-Zen is a large scintillator detector designed for neutrino-less double-beta decay search. This detector is also useful to detect dark matter bound state formations with nuclei. The result from the KamLAND-Zen 400 dataset is reported.
Ten years of cosmic muons observation with Borexino
Authors: D’Angelo Davide , Agostini M. , Altenmüller K. , Appel S. , Atroshchenko V. , Bagdasarian Z. , Basilico D. , Bellini G. , Benziger J. , Bick D. , Bonfini G. , Bravo D. , Caccianiga B. , Calaprice F. , Caminata A. , Cappelli L. , Cavalcante P. , Cavanna F. , Chepurnov A. , Choi K. , D’Angelo D. , Davini S. , Derbin A. , Di Giacinto A. , Di Marcello V. , Ding X.F. , Di Ludovico A. , Di Noto L. , Drachnev I. , Fomenko K. , Formozov A. , Franco D. , Gabriele F. , Galbiati C. , Gschwender M. , Ghiano C. , Giammarchi M. , Goretti A. , Gromov M. , Guffanti D. , Hagner C. , Hungerford E. , Ianni Aldo , Ianni Andrea , Jany A. , Jeschke D. , Kumaran S. , Kobychev V. , Korga G. , Lachenmaier T. , Laubenstein M. , Litvinovich E. , Lombardi P. , Lomskaya I. , Ludhova L. , Lukyanchenko G. , Lukyanchenko L. , Machulin I. , Manuzio G. , Marcocci S. , Maricic J. , Martyn J. , Meroni E. , Meyer M. , Miramonti L. , Misiaszek M. , Muratova V. , Neumair B. , Nieslony M. , Oberauer L. , Orekhov V. , Ortica F. , Pallavicini M. , Papp L. , Penek O. , Pietrofaccia L. , Pilipenko N. , Pocar A. , Raikov G. , Ranalli M.T. , Ranucci G. , Razeto A. , Re A. , Redchuk M. , Romani A. , Rossi N. , Rottenanger S. , Schönert S. , Semenov D. , Skorokhvatov M. , Smirnov O. , Sotnikov A. , Suvorov Y. , Tartaglia R. , Testera G. , Thurn J. , Unzhakov E. , Vishneva A. , Vogelaar R.B. , von Feilitzsch F. , Wojcik M. , Wurm M. , Zaimidoroga O. , Zavatarelli S. , Zuber K. , Zuzel G.
Published: May 2021

The Borexino detector at Gran Sasso has now accumulated over ten years of continuous data which represent a magnificent opportunity to study the cosmic muon flux at a deep underground location. We present here a precision measurement of the flux and of the expected seasonal modulation. We present the correlation with the atmospheric temperature variations from global atmospheric models. We measure the correlation parameters and infer the kaon-to-pion ratio in the production of cosmic muons from high energy primaries. We also find evidence of a long term modulation that is not present in the atmospheric data and we investigate a possible positive correlation with the solar activity. Finally we observe a seasonal modulation of the production rate of cosmogenic neutrons that is in phase with the muon modulation but shows a surprisingly larger amplitude.
Prospects for THEIA: an advanced liquid scintillator neutrino experiment
Authors: Guffanti D
Published: May 2021

THEIA is a proposed large-scale neutrino experiment based on advanced liquid scintillator and readout by high-quantum efficiency and fast photosensors. In order to combine the advantages of water Cherenkov detectors (i.e. large mass, direction reconstruction and low cost) with the ones of liquid scintillator (high light yield, low threshold) THEIA will deploy a Water-based Liquid Scintillator, which is currently at the center of an active R&D program. This detector concept has the potential to pursue a broad physics program that is summarized in this contribution. As a long baseline experiment installed at Homestake, THEIA will be complementary to the forthcoming DUNE experiment for the determination of the neutrino mass hierarchy and of the CP phase. At the same time, the low energy threshold and efficient neutron tagging makes THEIA an excellent detector for solar and supernova neutrinos measurements as well as for the search of neutrinoless ββ-decay and of other rare phenomena.
Development of new trigger system for KamLAND2-Zen
Authors: Takeuchi Atsuto , Kawada Nanami
Published: May 2021

KamLAND2-Zen is the future plan for the existing KamLND-Zen experiment, which will search for neutrinoless double-beta decay. In this experiment, muon spallation products are expected to be the main background. Spallation backgrounds can be tagged by delayed coincidence with neutrons emitted in spallation. Therefore, it is important to detect neutrons with high efficiency. However, enhancement of light yield will increase after-pulses and fake triggers due to them resulting in DAQ deadtime and low detection efficiency of neutrons. To solve this problem, a new trigger scheme which uses simultaneous hit of neighboring PMTs was developed. According to a simulation performed with real PMT waveforms, this scheme is expected to improve neutron detection efficiency from 54% to 89%. Consequently 99% of 10C background events can be tagged.
Evaluation of position dependent performance of 3-inch PMTs for Multi-PMT development
Authors: Izumi N , Ishitsuka M , Kuze M , Nishimura Y , Quilain B
Published: May 2021

Hyper-Kamiokande detector is proposed as a next generation underground water Cherenkov detector in Japan, and is planned to be an order of magnitude bigger than its predecessor, Super-Kamiokande. In order to further improve the detector capabilities in both low and high energy sectors, the multi-PMT modules instrumented with multiple 3-inch PMTs are being developed, in addition to the improved high quantum efficiency 20-inch PMTs. We developed a moveable laser system that can illuminate different positions on the photocathode to measure the characterization of the 3-inch PMTs as a function of the position on the photocathode.
Status of JSNS2 - J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source
Authors: Rott Carsten
Published: May 2021

The JSNS2 experiment will search for neutrino oscillations with Δm2 ≃ 1 eV2 from

v
¯

μ

to

v
¯

e

, detected via the inverse beta decay (IBD) reaction

(

v
¯

e

+
p
→

e
+

+
n
)

and tagged via gammas from neutron capture on Gadolinium. A 3 GeV 1 MW proton beam incident on a mercury target at the Materials and Life Science Experimental Facility at J-PARC produces an intense neutrino flux from muon decay at rest

(

μ
+

→

e
+

+

v
¯

μ

+

v
e

)

. The first of two 50 tons liquid scintillator detectors is nearly completed and will be located at a distance of 24 m from the neutrino source. JSNS2 can directly test the LSND anomaly and is expected to start taking data in early 2020.
Study of the radon removal and detection for JUNO
Authors: Zhang Y.P , Guo C. , Liu J.C. , Zhang P. , Yang C.G.
Published: May 2021

The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose underground experiment with primary physics goal the neutrino mass hierarchy determination. For the sake of suppressing the radioactivity from the surrounding rocks and tagging the cosmic muons, the central detector is surrounded by a water Cherenkov detector. Therefore, the strict requirements are put forward for intrinsic radioactivity in water, i.e., the radon concentration should be less than 0.2 Bq/m3. In order to monitor the radon concentration in water, a high sensitivity detector has been developed. The degassing membrane device and the micro-bubble generator were installed in the JUNO prototype water system to study the radon removal in water.
Research on Task Analysis Framework for Unconventional Sudden Decision-making Problems
Authors: Pengfei Peng , Linru Zhou , Li Gong
Published: May 2021

In view of the structural uncertainty, suddenness and unpredictability of the current unconventional sudden decision-making problems, the analysis of the unconventional sudden emergency decision-making task analysis proposes a task analysis from task description to scenario construction and task analysis plan optimization process. In the task analysis, the joint extraction model is used to extract the task entities and the relationship between the task entities in the decision-making problem; the scenario construction is used to supplement the task description and constraint conditions; the cyclic neural network is used to simulate the thinking of the decision maker to complete the task analysis plan optimization. This analysis method adds hidden information such as the environment and constraints in the analysis to the analysis process, which is conducive to improving the suitability of the task analysis plan, and has application and promotion value in the research of task analysis framework for unconventional sudden decision problems.
Multi-exposure image fusion based on recursive filter
Authors: Li Ting , Xie Kai , Li Tong , Yan Yubing , Huang Ling
Published: May 2021

Multi-exposure image fusion technology is to fuse images of the same scene with different exposures into a high-quality image that contains more scene information. This paper proposes a multi-exposure image fusion method based on a recursive filter. The method first calculates three characteristic indicators of the multi-exposure image sequence: image contrast, entropy, and exposure information. And use three characteristic indicators to estimate the initial image fusion. In order to obtain a more accurate weight map for image fusion, a recursive filter is used to refine the weight map. Finally, the weighted sum method is used to construct the fused image. The experimental results show that the fusion results obtained by the algorithm in this paper have high image clarity, better subjective visual fusion effects and objective performance indicators, and maintain a high computational efficiency.
Detecting Fake News With Machine Learning
Authors: Huang Jeffrey
Published: May 2021

Fake news is increasingly prevalent in our modern digital age. It ranges from misleading writing and disguised opinion pieces to pieces of satire. With the advent of social media and the growth of the internet in the 21st century, the creation, access, and spread of false information are rapidly increasing in volume. Widespread fake news can foster many problems, including misinformed public opinions and dangerous levels of political division. Current methods of tackling fake news revolve around manual reviews, fact-checking organizations, and black-listing unreliable sources. However, many of these tactics are easily exploited or ineffective. This paper applied machine learning on a Kaggle dataset to predict whether an article of news was real or fake. We applied three different classifiers, all yielding promising results.
How NLOS Signals affect GNSS relative positioning
Authors: Ye Xiaozhou , Ma Pengcheng , Liu Wenxiang , Wang Feixue
Published: May 2021

Owing to the existence of non-line-of-sight (NLOS) signals in global navigation satellite system (GNSS) challenged environment, the accuracy of GNSS relative positioning is seriously damaged. This paper demonstrates the effects of NLOS measurement error on GNSS relative positioning for short-baseline in both theory and field test. The results show that the effects of NLOS signal in both pseudorange and carrier phase make the ambiguity unable to be successfully fixed. In addition, we have found that after removing the labelled NLOS observations, the positioning accuracy can be significantly improved. The more the available LOS satellites, the more the robustness against NLOS satellites of the ambiguity resolution. This implies that GNSS Multi-Frequency Multi-System technology might improve the performance of GNSS relative positioning because there would be sufficient LOS signals after the NLOS signals are removed.