bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantifying the environmental limits to fire spread in grassy ecosystems
Authors: Cardoso Anabelle W. , Archibald Sally , Bond William J. , Coetsee Corli , Forrest Matthew , Govender Navashni , Lehmann David , Makaga Loïc , Mpanza Nokukhanya , Ndong Josué Edzang , Koumba Pambo Aurélie Flore , Strydom Tercia , Tilman David , Wragg Peter D. , Staver A. Carla
Published: June 2022

Modeling fire spread as an infection process is intuitive: An ignition lights a patch of fuel, which infects its neighbor, and so on. Infection models produce nonlinear thresholds, whereby fire spreads only when fuel connectivity and infection probability are sufficiently high. These thresholds are fundamental both to managing fire and to theoretical models of fire spread, whereas applied fire models more often apply quasi-empirical approaches. Here, we resolve this tension by quantifying thresholds in fire spread locally, using field data from individual fires (
n
= 1,131) in grassy ecosystems across a precipitation gradient (496 to 1,442 mm mean annual precipitation) and evaluating how these scaled regionally (across 533 sites) and across time (1989 to 2012 and 2016 to 2018) using data from Kruger National Park in South Africa. An infection model captured observed patterns in individual fire spread better than competing models. The proportion of the landscape that burned was well described by measurements of grass biomass, fuel moisture, and vapor pressure deficit. Regionally, averaging across variability resulted in quasi-linear patterns. Altogether, results suggest that models aiming to capture fire responses to global change should incorporate nonlinear fire spread thresholds but that linear approximations may sufficiently capture medium-term trends under a stationary climate.
Glycan degradation promotes macroautophagy
Authors: Baudot Alice D. , Wang Victoria M.-Y. , Leach Josh D. , O’Prey Jim , Long Jaclyn S. , Paulus-Hock Viola , Lilla Sergio , Thomson David M. , Greenhorn John , Ghaffar Farah , Nixon Colin , Helfrich Miep H. , Strathdee Douglas , Pratt Judith , Marchesi Francesco , Zanivan Sara , Ryan Kevin M.
Published: June 2022

Macroautophagy promotes cellular homeostasis by delivering cytoplasmic constituents to lysosomes for degradation [Mizushima,Nat. Cell Biol.20, 521–527 (2018)]. However, while most studies have focused on the mechanisms of protein degradation during this process, we report here that macroautophagy also depends on glycan degradation via the glycosidase, α-l-fucosidase 1 (FUCA1), which removes fucose from glycans. We show that cells lacking FUCA1 accumulate lysosomal glycans, which is associated with impaired autophagic flux. Moreover, in a mouse model of fucosidosis—a disease characterized by inactivating mutations inFUCA1[Stepienet al.,Genes (Basel)11, E1383 (2020)]—glycan and autophagosome/autolysosome accumulation accompanies tissue destruction. Mechanistically, using lectin capture and mass spectrometry, we identified several lysosomal enzymes with altered fucosylation in FUCA1-null cells. Moreover, we show that the activity of some of these enzymes in the absence of FUCA1 can no longer be induced upon autophagy stimulation, causing retardation of autophagic flux, which involves impaired autophagosome–lysosome fusion. These findings therefore show that dysregulated glycan degradation leads to defective autophagy, which is likely a contributing factor in the etiology of fucosidosis.
Tas2R activation relaxes airway smooth muscle by release of Gα
t
targeting on AChR signaling
Authors: Zhou Yu-Wei , Sun Jie , Wang Ye , Chen Cai-Ping , Tao Tao , Ma Ming , Chen Xin , Zhang Xue-Na , Yang Li-Yuan , Zhang Zhong-Liang , Li Ye-Qiong , Jiang Zhi-Hui , Qiu Tian-Tian , Wang Han , Pan Yang , Zhang Jian , Chen Hua-Qun , Wang Pei , Zhu Min-Sheng
Published: June 2022

Both chronic obstructive pulmonary disease (COPD) and asthma are severe respiratory diseases. Bitter receptor–mediated bronchodilation is a potential therapy for asthma, but the mechanism underlying the agonistic relaxation of airway smooth muscle (ASM) is not well defined. By exploring the ASM relaxation mechanism of bitter substances, we observed that pretreatment with the bitter substances nearly abolished the methacholine (MCh)-induced increase in the ASM cell (ASMC) calcium concentration, thereby suppressing the calcium-induced contraction release. The ASM relaxation was significantly inhibited by simultaneous deletion of three Gα
t
proteins, suggesting an interaction between Tas2R and AChR signaling cascades in the relaxation process. Biochemically, the Gα
t
released by Tas2R activation complexes with AChR and blocks the Gα
q
cycling of AChR signal transduction. More importantly, a bitter substance, kudinoside A, not only attenuates airway constriction but also significantly inhibits pulmonary inflammation and tissue remodeling in COPD rats, indicating its modulation of additional Gα
q
-associated pathological processes. Thus, our results suggest that Tas2R activation may be an ideal strategy for halting multiple pathological processes of COPD.
Slow oscillations promote long-range effective communication: The key for memory consolidation in a broken-down network
Authors: Niknazar Hamid , Malerba Paola , Mednick Sara C.
Published: June 2022

A prominent and robust finding in cognitive neuroscience is the strengthening of memories during nonrapid eye movement (NREM) sleep, with slow oscillations (SOs;<1Hz) playing a critical role in systems-level consolidation. However, NREM generally shows a breakdown in connectivity and reduction of synaptic plasticity with increasing depth: a brain state seemingly unfavorable to memory consolidation. Here, we present an approach to address this apparent paradox that leverages an event-related causality measure to estimate directional information flow during NREM in epochs with and without SOs. Our results confirm that NREM is generally a state of dampened neural communication but reveals that SOs provide two windows of enhanced large-scale communication before and after the SO trough. These peaks in communication are significantly higher when SOs are coupled with sleep spindles compared with uncoupled SOs. To probe the functional relevance of these SO-selective peaks of information flow, we tested the temporal and topographic conditions that predict overnight episodic memory improvement. Our results show that global, long-range communication during SOs promotes sleep-dependent systems consolidation of episodic memories. A significant correlation between peaks of information flow and memory improvement lends predictive validity to our measurements of effective connectivity. In other words, we were able to predict memory improvement based on independent electrophysiological observations during sleep. This work introduces a noninvasive approach to understanding information processing during sleep and provides a mechanism for how systems-level brain communication can occur during an otherwise low connectivity sleep state. In short, SOs are a gating mechanism for large-scale neural communication, a necessary substrate for systems consolidation and long-term memory formation.
Tankyrases inhibit innate antiviral response by PARylating VISA/MAVS and priming it for RNF146-mediated ubiquitination and degradation
Authors: Xu Yan-Ran , Shi Meng-Ling , Zhang Yu , Kong Na , Wang Cong , Xiao Yi-Feng , Du Shi-Shen , Zhu Qi-Yun , Lei Cao-Qi
Published: June 2022

During viral infection, sensing of viral RNA by retinoic acid–inducible gene-I–like receptors (RLRs) initiates an antiviral innate immune response, which is mediated by the mitochondrial adaptor protein VISA (virus-induced signal adaptor; also known as mitochondrial antiviral signaling protein [MAVS]). VISA is regulated by various posttranslational modifications (PTMs), such as polyubiquitination, phosphorylation,
O
-linked β-d-
N
-acetylglucosaminylation (O-GlcNAcylation), and monomethylation. However, whether other forms of PTMs regulate VISA-mediated innate immune signaling remains elusive. Here, we report that Poly(ADP-ribosyl)ation (PARylation) is a PTM of VISA, which attenuates innate immune response to RNA viruses. Using a biochemical purification approach, we identified tankyrase 1 (TNKS1) as a VISA-associated protein. Viral infection led to the induction of TNKS1 and its homolog TNKS2, which translocated from cytosol to mitochondria and interacted with VISA. TNKS1 and TNKS2 catalyze the PARylation of VISA at Glu137 residue, thereby priming it for K48-linked polyubiquitination by the E3 ligase Ring figure protein 146 (RNF146) and subsequent degradation. Consistently, TNKS1, TNKS2, or RNF146 deficiency increased the RNA virus–triggered induction of downstream effector genes and impaired the replication of the virus. Moreover, TNKS1- or TNKS2-deficient mice produced higher levels of type I interferons (IFNs) and proinflammatory cytokines after virus infection and markedly reduced virus loads in the brains and lungs. Together, our findings uncover an essential role of PARylation of VISA in virus-triggered innate immune signaling, which represents a mechanism to avoid excessive harmful immune response.
Interaction between S4 and the phosphatase domain mediates electrochemical coupling in voltage-sensing phosphatase (VSP)
Authors: Mizutani Natsuki , Kawanabe Akira , Jinno Yuka , Narita Hirotaka , Yonezawa Tomoko , Nakagawa Atsushi , Okamura Yasushi
Published: June 2022

Voltage-sensing phosphatase (VSP) consists of a voltage sensor domain (VSD) and a cytoplasmic catalytic region (CCR), which is similar to phosphatase and tensin homolog (PTEN). How the VSD regulates the innate enzyme component of VSP remains unclear. Here, we took a combined approach that entailed the use of electrophysiology, fluorometry, and structural modeling to study the electrochemical coupling in
Ciona intestinalis
VSP. We found that two hydrophobic residues at the lowest part of S4 play an essential role in the later transition of VSD-CCR coupling. Voltage clamp fluorometry and disulfide bond locking indicated that S4 and its neighboring linker move as one helix (S4-linker helix) and approach the hydrophobic spine in the CCR, a structure located near the cell membrane and also conserved in PTEN. We propose that the hydrophobic spine operates as a hub for translating an electrical signal into a chemical one in VSP.
IFT80 negatively regulates osteoclast differentiation via association with Cbl-b to disrupt TRAF6 stabilization and activation
Authors: Deepak Vishwa , Yang Shu-ting , Li Ziqing , Li Xinhua , Ng Andrew , Xu Ding , Li Yi-Ping , Oursler Merry Jo , Yang Shuying
Published: June 2022

Excess bone loss due to increased osteoclastogenesis is a significant clinical problem. Intraflagellar transport (IFT) proteins have been reported to regulate cell growth and differentiation. The role of IFT80, an IFT complex B protein, in osteoclasts (OCs) is completely unknown. Here, we demonstrate that deletion of IFT80 in the myeloid lineage led to increased OC formation and activity accompanied by severe bone loss in mice. IFT80 regulated OC formation by associating with Casitas B-lineage lymphoma proto-oncogene-b (Cbl-b) to promote protein stabilization and proteasomal degradation of tumor necrosis factor (TNF) receptor–associated factor 6 (TRAF6). IFT80 knockdown resulted in increased ubiquitination of Cbl-b and higher TRAF6 levels, thereby hyperactivating the receptor activator of nuclear factor-κβ (NF-κβ) ligand (RANKL) signaling axis and increased OC formation. Ectopic overexpression of IFT80 rescued osteolysis in a calvarial model of bone loss. We have thus identified a negative function of IFT80 in OCs.
Schools under mandatory testing can mitigate the spread of SARS-CoV-2
Authors: Diederichs Marc , van Ewijk Reyn , Isphording Ingo E. , Pestel Nico
Published: June 2022

We use event study models based on staggered summer vacations in Germany to estimate the effect of school reopenings after the summer of 2021 on the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Estimations are based on daily counts of confirmed coronavirus infections across all 401 German counties. A central antipandemic measure in German schools included mandatory rapid testing multiple times per week. Our results are consistent with mandatory testing contributing to the containment of the viral spread. We find a short-term increase in infection rates right after summer breaks, indicating the uncovering of otherwise undetected (asymptomatic) cases through the testing. After a period of about 2 wk after school reopenings, the growth of case numbers is smaller in states that reopened schools compared with the control group of states still in summer break. The results show a similar pattern for older age groups as well, arguably as a result of detected clusters through the school testing. This means that under certain conditions, open schools can play a role in containing the spread of the virus. Our results suggest that closing schools as a means to reduce infections may have unintended consequences by giving up surveillance and should be considered only as a last resort.
Structural basis for the recognition of the bacterial tyrosine kinase Wzc by its cognate tyrosine phosphatase Wzb
Authors: Alphonse Sébastien , Djemil Imane , Piserchio Andrea , Ghose Ranajeet
Published: June 2022

Bacterial tyrosine kinases (BY-kinases) comprise a family of protein tyrosine kinases that are structurally distinct from their functional counterparts in eukaryotes and are highly conserved across the bacterial kingdom. BY-kinases act in concert with their counteracting phosphatases to regulate a variety of cellular processes, most notably the synthesis and export of polysaccharides involved in biofilm and capsule biogenesis. Biochemical data suggest that BY-kinase function involves the cyclic assembly and disassembly of oligomeric states coupled to the overall phosphorylation levels of a C-terminal tyrosine cluster. This process is driven by the opposing effects of intermolecular autophosphorylation, and dephosphorylation catalyzed by tyrosine phosphatases. In the absence of structural insight into the interactions between a BY-kinase and its phosphatase partner in atomic detail, the precise mechanism of this regulatory process has remained poorly defined. To address this gap in knowledge, we have determined the structure of the transiently assembled complex between the catalytic core of the
Escherichia coli
(K-12) BY-kinase Wzc and its counteracting low–molecular weight protein tyrosine phosphatase (LMW-PTP) Wzb using solution NMR techniques. Unambiguous distance restraints from paramagnetic relaxation effects were supplemented with ambiguous interaction restraints from static spectral perturbations and transient chemical shift changes inferred from relaxation dispersion measurements and used in a computational docking protocol for structure determination. This structure presents an atomic picture of the mode of interaction between an LMW-PTP and its BY-kinase substrate, and provides mechanistic insight into the phosphorylation-coupled assembly/disassembly process proposed to drive BY-kinase function.
Multi-
e
GO: An in silico lens to look into protein aggregation kinetics at atomic resolution
Authors: Scalone Emanuele , Broggini Luca , Visentin Cristina , Erba Davide , Bačić Toplek Fran , Peqini Kaliroi , Pellegrino Sara , Ricagno Stefano , Paissoni Cristina , Camilloni Carlo
Published: June 2022

Protein aggregation into amyloid fibrils is the archetype of aberrant biomolecular self-assembly processes, with more than 50 associated diseases that are mostly uncurable. Understanding aggregation mechanisms is thus of fundamental importance and goes in parallel with the structural characterization of the transient oligomers formed during the process. Oligomers have been proven elusive to high-resolution structural techniques, while the large sizes and long time scales, typical of aggregation processes, have limited the use of computational methods to date. To surmount these limitations, we here present multi-
e
GO, an atomistic, hybrid structure-based model which, leveraging the knowledge of monomers conformational dynamics and of fibril structures, efficiently captures the essential structural and kinetics aspects of protein aggregation. Multi-
e
GO molecular dynamics simulations can describe the aggregation kinetics of thousands of monomers. The concentration dependence of the simulated kinetics, as well as the structural features of the resulting fibrils, are in qualitative agreement with in vitro experiments carried out on an amyloidogenic peptide from Transthyretin, a protein responsible for one of the most common cardiac amyloidoses. Multi-
e
GO simulations allow the formation of primary nuclei in a sea of transient lower-order oligomers to be observed over time and at atomic resolution, following their growth and the subsequent secondary nucleation events, until the maturation of multiple fibrils is achieved. Multi-
e
GO, combined with the many experimental techniques deployed to study protein aggregation, can provide the structural basis needed to advance the design of molecules targeting amyloidogenic diseases.
The nature of proton-coupled electron transfer in a blue light using flavin domain
Authors: Zhou Zhongneng , Chen Zijing , Kang Xiu-Wen , Zhou Yalin , Wang Bingyao , Tang Siwei , Zou Shuhua , Zhang Yifei , Hu Qiaoyu , Bai Fang , Ding Bei , Zhong Dongping
Published: June 2022

Proton-coupled electron transfer (PCET) is key to the activation of the blue light using flavin (BLUF) domain photoreceptors. Here, to elucidate the photocycle of the central FMN-Gln-Tyr motif in the BLUF domain of OaPAC, we eliminated the intrinsic interfering W90 in the mutant design. We integrated the stretched exponential function into the target analysis to account for the dynamic heterogeneity arising from the active-site solvation relaxation and the flexible H-bonding network as shown in the molecular dynamics simulation results, facilitating a simplified expression of the kinetics model. We find that, in both the functional wild-type (WT) and the nonfunctional Q48E and Q48A, forward PCET happens in the range of 105 ps to 344 ps, with a kinetic isotope effect (KIE) measured to be ∼1.8 to 2.4, suggesting that the nature of the forward PCET is concerted. Remarkably, only WT proceeds with an ultrafast reverse PCET process (31 ps, KIE = 4.0), characterized by an inverted kinetics of the intermediate FMNH˙. Our results reveal that the reverse PCET is driven by proton transfer via an intervening imidic Gln.
Loss of adipose TET proteins enhances β-adrenergic responses and protects against obesity by epigenetic regulation of β3-AR expression
Authors: Byun Seongjun , Lee Chan Hyeong , Jeong Hyeongmin , Kim Hyejin , Kwon Hyug Moo , Park Sungho , Myung Kyungjae , An Jungeun , Ko Myunggon
Published: June 2022

β-adrenergic receptor (β-AR) signaling plays predominant roles in modulating energy expenditure by triggering lipolysis and thermogenesis in adipose tissue, thereby conferring obesity resistance. Obesity is associated with diminished β3-adrenergic receptor (β3-AR) expression and decreased β-adrenergic responses, but the molecular mechanism coupling nutrient overload to catecholamine resistance remains poorly defined. Ten-eleven translocation (TET) proteins are dioxygenases that alter the methylation status of DNA by oxidizing 5-methylcytosine to 5-hydroxymethylcytosine and further oxidized derivatives. Here, we show that TET proteins are pivotal epigenetic suppressors of β3-AR expression in adipocytes, thereby attenuating the responsiveness to β-adrenergic stimulation. Deletion of all three
Tet
genes in adipocytes led to increased β3-AR expression and thereby enhanced the downstream β-adrenergic responses, including lipolysis, thermogenic gene induction, oxidative metabolism, and fat browning in vitro and in vivo. In mouse adipose tissues,
Tet
expression was elevated after mice ate a high-fat diet. Mice with adipose-specific ablation of all TET proteins maintained higher levels of β3-AR in both white and brown adipose tissues and remained sensitive to β-AR stimuli under high-fat diet challenge, leading to augmented energy expenditure and decreased fat accumulation. Consequently, they exhibited improved cold tolerance and were substantially protected from diet-induced obesity, inflammation, and metabolic complications, including insulin resistance and hyperlipidemia. Mechanistically, TET proteins directly repressed
β3-AR
transcription, mainly in an enzymatic activity-independent manner, and involved the recruitment of histone deacetylases to increase deacetylation of its promoter. Thus, the TET–histone deacetylase–β3-AR axis could be targeted to treat obesity and related metabolic diseases.
Phylogenomic and functional characterization of an evolutionary conserved cytochrome P450-based insecticide detoxification mechanism in bees
Authors: Haas Julian , Hayward Angela , Buer Benjamin , Maiwald Frank , Nebelsiek Birgit , Glaubitz Johannes , Bass Chris , Nauen Ralf
Published: June 2022

The regulatory process for assessing the risks of pesticides to bees relies heavily on the use of the honeybee,Apis mellifera, as a model for other bee species. However, the validity of usingA. melliferaas a surrogate for otherApisand non-Apisbees in pesticide risk assessment has been questioned. Related to this line of research, recent work onA. melliferahas shown that specific P450 enzymes belonging to the CYP9Q subfamily act as critically important determinants of insecticide sensitivity in this species by efficiently detoxifying certain insecticide chemotypes. However, the extent to which the presence of functional orthologs of these enzymes is conserved across the diversity of bees is unclear. Here we used a phylogenomic approach to identify > 100 putative CYP9Q functional orthologs across 75 bee species encompassing all major bee families. Functional analysis of 26 P450s from 20 representative bee species revealed that P450-mediated detoxification of certain systemic insecticides, including the neonicotinoid thiacloprid and the butenolide flupyradifurone, is conserved across all major bee pollinator families. However, our analyses also reveal thatCYP9Q-related genes are not universal to all bee species, with some Megachilidae species lacking such genes. Thus, our results reveal an evolutionary conserved capacity to metabolize certain insecticides across all major bee families while identifying a small number of bee species where this function may have been lost. Furthermore, they illustrate the potential of a toxicogenomic approach to inform pesticide risk assessment for nonmanaged bee species by predicting the capability of bee pollinator species to break down synthetic insecticides.
The role of object distance and gender in Persian compliment responses
Authors: Sarkhosh Mehdi
Published: June 2022

This study investigated the effect of the distance of the object of the compliment from the complimentee on
compliment responses in Persian. A further aim of the study was to understand whether gender of the complimentee made a difference
to the response pattern. To this end, 2652 Persian compliment responses were elicited through Discourse Completion Tasks from 563
BA students majoring in twenty disciplines at a university in Iran. The findings revealed that the distance of the object of the
compliment did not influence the degree of acceptance or rejection of the compliment. It was also found that Iranian university
students’ compliment response behavior, mostly characterized by the rejection or evasion of compliments was shifting toward
accepting compliments. This observation is attributed to increasing chances of exposure to and interaction with foreign media such
as satellite TV, the Internet, foreign films, series, etc. among Persian university students.
Highly protective antimalarial antibodies via precision library generation and yeast display screening
Authors: Banach Bailey B. , Tripathi Prabhanshu , Da Silva Pereira Lais , Gorman Jason , Nguyen Thuy Duong , Dillon Marlon , Fahad Ahmed S. , Kiyuka Patience K. , Madan Bharat , Wolfe Jacy R. , Bonilla Brian , Flynn Barbara , Francica Joseph R. , Hurlburt Nicholas K. , Kisalu Neville K. , Liu Tracy , Ou Li , Rawi Reda , Schön Arne , Shen Chen-Hsiang , Teng I-Ting , Zhang Baoshan , Pancera Marie , Idris Azza H. , Seder Robert A. , Kwong Peter D. , DeKosky Brandon J.
Published: June 2022

The monoclonal antibody CIS43 targets the Plasmodium falciparum circumsporozoite protein (PfCSP) and prevents malaria infection in humans for up to 9 mo following a single intravenous administration. To enhance the potency and clinical utility of CIS43, we used iterative site-saturation mutagenesis and DNA shuffling to screen precise gene-variant yeast display libraries for improved PfCSP antigen recognition. We identified several mutations that improved recognition, predominately in framework regions, and combined these to produce a panel of antibody variants. The most improved antibody, CIS43_Var10, had three mutations and showed approximately sixfold enhanced protective potency in vivo compared to CIS43. Co-crystal and cryo-electron microscopy structures of CIS43_Var10 with the peptide epitope or with PfCSP, respectively, revealed functional roles for each of these mutations. The unbiased site-directed mutagenesis and screening pipeline described here represent a powerful approach to enhance protective potency and to enable broader clinical use of antimalarial antibodies.
A microfabricated semi-packed column coated with porous layer and ionic liquid for the separation of characteristic markers of non-alcoholic fatty liver disease
Authors: Shi Lujia , Wang Hairong , Wu Xinyu , Wang Dazuo , Zhang Qunming , Han Baoqing , Sun Jianhai , Wei Xueyong , Li Changqing
Published: June 2022

A serpentine-shaped semi-packed micro gas chromatography (GC) column with mesoporous inner surface and ionic liquid (IL) coating was developed for the separation of various typical volatile organic compounds in exhaled air. The mesoporous surface was prepared by coating silica nanoparticles on the inner surface of the micro GC column through static method and used as stationary phase support to improve the separation performance by its high surface area. The micro GC columns provide efficient separations for analytes including nonpolar (alkanes), weak polar (benzene series) and polar compounds (alcohols), as well as various typical markers of non-alcoholic fatty liver disease. The test results show that the resolution of most analytes is higher than 1.5, the elution peaks are symmetrical. Moreover, due to the chemical stability of IL, the micro GC had good repeatability, thermal stability and oxygen robustness. The maximum relative standard deviation of retention time was 0.44% in four weeks. During the programmed heating, a stable baseline was achieved and the baseline drift value was less than 4.8 mV when the operating temperature increased from 50 °C to 140 °C. The oxygen robustness was verified by a decrease of 7.2% in the peak capacity after exposure to dry air at 140 °C for 48 h. These characteristics showed the micro GC column is suitable for a portable breath analyzer.
Exploring symmetries in photoelectron holography with two-color linearly polarized fields
Authors: Rook T , Figueira de Morisson Faria C
Published: June 2022

We investigate photoelectron holography in bichromatic linearly polarized fields of commensurate frequencies rω and sω, with emphasis on the existing symmetries and for which values of the relative phase between the two driving waves they are kept or broken. Using group-theoretical methods, we show that, additionally to the well-known half-cycle symmetry, which is broken for r + s odd, there are reflection symmetries around the field zero crossings and maxima, which may or may not be kept, depending on how both waves are dephased. The three symmetries are always present for monochromatic fields, while for bichromatic fields this is not guaranteed, even if r + s is even and the half-cycle symmetry is retained. Breaking the half-cycle symmetry automatically breaks one of the other two, while, if the half-cycle symmetry is retained, the other two symmetries are either both kept or broken. We analyze how these features affect the ionization times and saddle-point equations for different bichromatic fields. We also provide general expressions for the relative phases ϕ which retain specific symmetries. As an application, we compute photoelectron momentum distributions for ω − 2ω fields with the Coulomb quantum orbit strong-field approximation and assess how holographic structures such as the fan, the spider and interference carpets behave, focusing on the reflection symmetries. The features encountered can be traced back to the field gradient and amplitude affecting ionization probabilities and quantum interference in different momentum regions.
Constraints on the detection of topological charge of optical vortices using self-reference interferometry
Authors: Wu Siyao , Chen Ling , Jing Ruiping , Zhang Baocheng
Published: June 2022

In this paper we investigate the self-reference interferometry of optical vortices using a Michelson interferometer. It is found that the detection of topological charge (TC) for optical vortices is constrained by some physical conditions. We present these conditions through theoretical analyses, numerical simulation and experimental results. The maximal detectable TCs are different for different parameters, which is helpful for the measurement of TC in practical applications. Within the range allowed by the constrained conditions, we also study the detection of TC using the interference pattern of a two-way optical vortex, by changing the inclined angle of one mirror of the Michelson interferometer.
Experimental study on the effect of argon shielding gas on the suppression of nitrogen arc anode ablation
Authors: Hu Ya-Hao , Meng Xian , Huang He-Ji , Shao Ke , Murphy Anthony B , Huang Kai , Sun Su-Rong , Wang Hai-Xing
Published: June 2022

The high heat flux density of the DC arc often leads to severe anode ablation, which is a key factor limiting the wider use of the DC plasma torches. In this study, a series of comparative experimental studies are conducted with the goal of suppressing nitrogen arc anode ablation by combining argon shielding flow and anode structure. It is found that for the planar electrode structure, the use of argon shielding gas can alleviate the ablation of the anode by nitrogen arc to some extent. If a boron nitride channel is installed on the anode surface to constrain the argon shielding flow, the electrode ablation can be significantly reduced. The experimental results show that there is no significant ablation on the anode surface after 1 h of operation of the nitrogen arc device with an arc current of 100 A. Further analysis reveals that, on the one hand, argon shielding gas can extend the range of motion of the nitrogen arc root along the anode surface and increase the speed of arc root motion, which has the effect of expanding the time-averaged arc anode attachment area. On the other hand, argon shielding gas can also increase the size of the nitrogen arc root and decrease the temperature of the arc root. The use of constraining channels can effectively control the range of motion of the arc root along the anode surface and strengthen the influence of argon shielding gas. The combination of these effects can substantially suppress the anode ablation of the DC arc device.
An all-sapphire fiber temperature sensor for high-temperature measurement
Authors: Cui Yang , Jiang Yi , Zhang Yutong , Feng Xinxing , Hu Jie , Jiang Lan
Published: June 2022

An all-sapphire high-temperature optical fiber sensor with an extrinsic Fabry–Perot interferometer (EFPI) structure is proposed and experimentally demonstrated. The EFPI structure of the sensor is composed of a sapphire ferrule with a sapphire fiber and a polished solid sapphire crystal rod. The first reflection occurs on the left end of the sapphire ferrule, and the second reflection occurs on the right end of the sapphire rod, forming double-beam interference. The interference signal is picked up by the sapphire fiber and transmitted to the white light interferometric demodulator by the multimode fiber. The picked-up signal is demodulated by the Fourier transform and interference algorithms. Experimental results show that the temperature response of the sensor is quadratic, and that the sensitivity changes linearly with a temperature range from room temperature to 1500 °C. The first-order thermal expansion coefficient and the second-order thermal expansion coefficient are 5.4575 × 10−6 °C−1 and 7.3755 × 10−9 °C−2, respectively. The thermal expansion coefficient is linearly related to temperature. Due to its all sapphire structures, this sensor solves the problem of thermal expansion coefficient mismatch, which was observed in a previous sensor made of sapphire and ceramic materials. In addition, it improves the high-temperature resistance, so it can be fully qualified for long-term high-temperature measurements above 1000 °C–1500 °C.
Gyrokinetic investigations of the electromagnetic geodesic acoustic mode
Authors: Xie Baoyi , Ye Lei , Chen Yang , Zhao Pengfei , Guo Wenfeng , Xiang Nong
Published: June 2022

The linear characteristics of the electromagnetic geodesic acoustic mode (GAM) are investigated numerically with the gyrokinetic code GEM. The results indicate that the electromagnetic effect has little influence on the frequency and damping rate of the GAM. The results also show that both

m
=

1

and

m
=

2

poloidal magnetic components of the GAM exist, and the

m
=
1

magnetic component has comparable sine and cosine components, while the

m
=
2

magnetic component is dominated by the sine component, where

m

is the poloidal mode number. In addition, the amplitudes of various magnetic components increase with respect to the ratio of plasma pressure to magnetic pressure

β

and safety factor

q

. Most importantly, the amplitude of the

m
=
1

magnetic component is comparable to, or even slightly larger than, that of the

m
=
2

magnetic component. It is also found that the trapped electron effect may be important for the magnetic components. Furthermore, the various magnetic components are compared with the previous analytical results and some discussions are given.
Characterization of OH species in kHz He/H2O atmospheric pressure dielectric barrier discharges
Authors: Lin Jyun-Yu , Huang Cheng-Liang , Chen Jui-Wen , Lin Kun-Mo , Ou Chia-Chun , Wu Yu-Hsiang
Published: June 2022

This work investigates experimentally and numerically the chemical kinetics of OH species generated in kHz helium atmospheric-pressure dielectric barrier discharges with different H2O concentrations. The OH densities of cases are determined from measurements of the ultraviolet absorption spectroscopy (UVAS) system with transition parameters evaluated by LIFBASE. The 1D plasma fluid model (PFM) with compiled chemistry covering chemical kinetics of helium, H2O, and interaction reactions of reactive species including the formation of charged cluster ions is employed to capture the discharge dynamics for analyzing mechanisms of OH species properly. The simulated current densities of cases with 0.8% and 2.0% H2O concentrations increase from 29 to 51 A m−2, agreeing with experimental measurements. The simulated OH density increases from 1.7 × 1019 m−3 to 2.4 × 1019 m−3 as the H2O concentration increases from 0.4% to 2.0%, agreeing with OH densities interpreted from the UVAS system for cases with various H2O concentrations. In general, the 1D PFM developed captures the discharge behavior and predicts the OH densities of cases with different H2O concentrations. The simulated results reveal that the electron and H2O+ are essential species for OH production through dissociative reactions (e + H2O → e + OH + H) and (H2O+ + H2O → H+(H2O) + OH) contributing to 61% and 23% of OH production, respectively. It is observed that the OH self-recombination reaction (OH + OH + He → H2O2 + He) contributes to 32% of OH consumption as the dominant reaction. Moreover, the stepwise recombination reactions (OH + H2O2 → H2O + HO2 and OH + HO2 → O2 + H2O) initiated by OH species contribute to the overall 27% of OH consumption as another dominant mechanism. The Penning ionization reactions involving water molecules are the dominant reactions for electron production in the present discharge with H2O up to 0.8%, then the electron-impact ionization becomes the dominant reaction for electron production in cases with higher H2O concentrations. As the essential species contributing to the OH consumption, H species is produced majorly from the dissociation reaction (e + H2O → e + OH + H). As one of the dominant OH production reactions, the dissociative attachment (e + H2O → H− + OH) is the dominant electron consumption reaction, resulting in the reactive H− species as the source of negative cluster ions. The high average reaction rates of dissociative attachment reactions consume most of the electrons after the breakdown, which leads to the variation of discharge current density. The saturation of OH species, which is observed experimentally and numerically, is attributed to the transition of electron chemical kinetics and the recombination reactions of OH species.
Shape memory performance of PETG 4D printed parts under compression in cold, warm, and hot programming
Authors: Soleyman E , Rahmatabadi D , Soltanmohammadi K , Aberoumand M , Ghasemi I , Abrinia K , Baniassadi M , Wang K , Baghani M
Published: June 2022

The main novelty of this paper is the use of poly-ethylene terephthalate glycol (PETG) as a new shape memory polymer with excellent shape memory effect (SME) and printability. In addition, for the first time, the effect of programming temperature on PETG 4D printed samples has been studied. The amorphous nature of the PETG necessitates that molecular entanglements function as net points, which makes the role of programming temperature critical. SME comprehensively was conducted under compression loading for three programming conditions as well as various pre-strains. Significant results were obtained that summarized the gross differences exhibiting that the hot, cold, and warm programmed samples had the highest shape fixity, shape recovery, and stress recovery, respectively. The recovery and fixity ratios fell and rose, respectively, as the programming temperature increased. This effect intensified in hot programmed samples as the applied strain (loading time) expanded. So, the recovery ratio dropped from 68% to 50% by raising the pre-strain from 20% to 80%. The maximum stress recovery was 16 MPa, suggesting the fantastic benefit of warm programming conditions in PETG 4D printed parts. The locking mechanism (recovery force storage) for cold and hot programming is quite different. The dominant mechanism in cold programming is increasing internal energy by potential energy level enhancement. Contrary to this, in hot programming, the entropy reduction applies to the majority of the molecular segments, playing this role. By cooling, the state of the material changes from rubbery to glassy, and with this phase change, the oriented conformation of the deformed polymer chains is maintained under deformation. The results of this research can be used for various applications that require high shape fixity, recovery, or stress recovery.
Practical design of an electromagnet for the compression characterization of magnetorheological elastomers
Authors: Erenchun Aitor , Prieto Borja , Artetxe Gurutz , Gil-Negrete Nere
Published: June 2022

In this article, the compression characterization of silicon-based magnetorheological elastomers is addressed, emphasizing the difficulties associated to the test set-up in order to obtain accurate results of the behaviour of the material. Measurement errors associated to friction and vibration coupling due to design flaws in the electromagnet are solved by providing guidelines on an adequate electromagnet layout. The designed electromagnet allows conducting compression dynamic tests up to 300 Hz in specimens of dimensions 40 × 40 × 8 mm3, reaching magnetic flux densities in the order of 1000 mT and showing the expected increase in the dynamic stiffness. Additionally, the electromagnet might be used in the manufacturing and curing of anisotropic magnetorheological compression specimens.
Estimation of biquadratic and bicubic Heisenberg effective couplings from multiorbital Hubbard models
Authors: Soni Rahul , Kaushal Nitin , Şen Cengiz , Reboredo Fernando A , Moreo Adriana , Dagotto Elbio
Published: June 2022

We studied a multi-orbital Hubbard model at half-filling for two and three orbitals per site on a two-site cluster via full exact diagonalization, in a wide range for the onsite repulsion U, from weak to strong coupling, and multiple ratios of the Hund coupling J
H to U. The hopping matrix elements among the orbitals were also varied extensively. At intermediate and large U, we mapped the results into a Heisenberg model. For two orbitals per site, the mapping is into a S = 1 Heisenberg model where by symmetry both nearest-neighbor (S

i
⋅ S

j
) and

(

S

i

⋅

S

j

)

2

are allowed, with respective couplings J
1 and J
2. For the case of three orbitals per site, the mapping is into a S = 3/2 Heisenberg model with (S

i
⋅ S

j
),

(

S

i

⋅

S

j

)

2

, and

(

S

i

⋅

S

j

)

3

terms, and respective couplings J
1, J
2, and J
3. The strength of these coupling constants in the Heisenberg models depend on the U, J
H, and hopping amplitudes of the underlying Hubbard model. Our study provides a first crude estimate to establish bounds on how large the ratios J
2/J
1 and J
3/J
1 can be. We show that those ratios appear rather limited and, as a qualitative guidance, we conclude that J
2/J
1 is less than 0.4 and J
3/J
1 is less than 0.2, establishing bounds on effective models for strongly correlated Hubbard systems. Moreover, the intermediate Hubbard U regime was found to be the most promising to enhance J
2/J
1 and J
3/J
1.
Casimir effect in kinetic theory
Authors: Guo Xingyu , Zhao Jiaxing , Zhuang Pengfei
Published: June 2022

We study Casimir effect in equilibrium and non-equilibrium photon gas in the frame of quantum kinetic theory for U(1) gauge field. We derive first the transport, constraint and gauge fixing equations for the photon number distribution from Maxwell’s equations, and then calculate the energy variation and Casimir force for a finite system by considering boundary condition on the surface of the system. The Casimir force in vacuum is suppressed by the thermal motion of photons in equilibrium state, when considering two adiabatic plates. In non-equilibrium state, the photon induced Casimir force oscillates and decays with time and finally disappears.
An estimator for the lensing potential from galaxy number counts
Authors: Nistane Viraj , Jalilvand Mona , Carron Julien , Durrer Ruth , Kunz Martin
Published: June 2022

We derive an estimator for the lensing potential from galaxy number counts which contains a linear and a quadratic term. We show that this estimator has a much larger signal-to-noise ratio than the corresponding estimator from intensity mapping. We show that this is due to the additional lensing term in the number count angular power spectrum which is present already at linear order. We estimate the signal-to-noise ratio for future photometric surveys. We find that particularly at high redshifts, z ≳ 1.5, the signal to noise ratio can become of order 30. We therefore claim that number counts in photometric surveys are an excellent means to measure tomographic lensing spectra.
Complementarity of experiments in probing the non-relativistic effective theory of dark matter-nucleon interactions
Authors: Brenner Anja , Herrera Gonzalo , Ibarra Alejandro , Kang Sunghyun , Scopel Stefano , Tomar Gaurav
Published: June 2022

The non-relativistic effective theory of dark matter-nucleon interactions depends on 28 coupling strengths for dark matter spin up to 1/2. Due to the vast parameter space of the effective theory, most experiments searching for dark matter interpret the results assuming that only one of the coupling strengths is non-zero. On the other hand, dark matter models generically lead in the non-relativistic limit to several interactions which interfere with one another, therefore the published limits cannot be straightforwardly applied to model predictions. We present a method to determine a rigorous upper limit on the dark matter-nucleon interaction strength including all possible interferences among operators. We illustrate the method to derive model independent upper limits on the interaction strengths from the null search results from XENON1T, PICO-60 and IceCube. For some interactions, the limits on the coupling strengths are relaxed by more than one order of magnitude. We also present a method that allows to combine the results from different experiments, thus exploiting the synergy between different targets in exploring the parameter space of dark matter-nucleon interactions.
Impacts of gravitational-wave standard siren observations from Einstein Telescope and Cosmic Explorer on weighing neutrinos in interacting dark energy models
Authors: Jin Shang-Jie , Zhu Rui-Qi , Wang Ling-Feng , Li Hai-Li , Zhang Jing-Fei , Zhang Xin
Published: June 2022

Multi-messenger gravitational wave (GW) observation for binary neutron star merger events could provide a rather useful tool to explore the evolution of the Universe. In particular, for the third-generation GW detectors, i.e. the Einstein Telescope (ET) and the Cosmic Explorer (CE), proposed to be built in Europe and the U.S., respectively, lots of GW standard sirens with known redshifts could be obtained, which would exert great impacts on the cosmological parameter estimation. The total neutrino mass could be measured by cosmological observations, but such a measurement is model-dependent and currently only gives an upper limit. In this work, we wish to investigate whether the GW standard sirens observed by ET and CE could help improve the constraint on the neutrino mass, in particular in the interacting dark energy (IDE) models. We find that the GW standard siren observations from ET and CE can only slightly improve the constraint on the neutrino mass in the IDE models, compared to the current limit. The improvements in the IDE models are weaker than those in the standard cosmological model. Although the limit on neutrino mass can only be slightly updated, the constraints on other cosmological parameters can be significantly improved by using the GW observations.
Effect of arbitrary matter-geometry coupling on thermodynamics in f(R) theories of gravity
Authors: Wang Jun , Qiang Ling-Xuan , Zhang Tian-Qiang , Wang Zhi-Song , Li Lu-Yu
Published: June 2022

In this paper, the thermodynamics of the Friedmann–Lemaître–Robertson–Walker universe have been explored in f(R) theories of gravity with arbitrary matter-geometry coupling. The equivalence between the modified Friedmann equations with any spatial curvature and the first law of thermodynamics is confirmed, where the assumption of the entropy plays a crucial role. Then laws of thermodynamics in our considering case are obtained. They can reduce to the ones given in Einstein’s general theory of relativity under certain conditions. Moreover, a particular model is investigated through the obtained generalized second law of thermodynamics with observational results of cosmographic parameters.