bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations and Validation of Plasma Density, Temperature, and Abundance From a Langmuir Probe Onboard the International Space Station
Authors: Debchoudhury Shantanab , Barjatya Aroh , Minow Joseph I. , Coffey Victoria N. , Chandler Michael O. 
Published: September 2021

AbstractThe Floating Potential Measurement Unit (FPMU) has been operational on board the International Space Station (ISS) since 2006. One of the instruments in the FPMU suite is a spherical wide‐sweeping Langmuir probe, referred to as the WLP, which is sampled at a temporal cadence of 1 s giving in‐situ measurements of the plasma density and electron temperature. In this study we present our refinements to the Langmuir probe analysis algorithm that address the uncertainties associated with photoelectron emission current from the metal probe. We also derive the fraction of ions as a secondary data product, which shows decrease in abundance in the post‐midnight sector during solar minimum. The derived plasma parameters are compared and validated with an independent in‐situ measurement technique, overlapping ground‐based incoherent scatter radar measurements, as well as International Reference Ionosphere model output. The reduced data set spans the entire solar cycle 24 and shows the F‐region ionosphere variance at ISS altitudes.
Ion Kappa Distribution Parameters in the Magnetosphere of the Earth at Geocentric Distances Smaller Than 20 RE During Quiet Geomagnetic Conditions
Authors: Kirpichev I. P. , Antonova E. E. , Stepanova M. , Eyelade A. V. , Espinoza C. M. , Ovchinnikov I. L. , Vorobjev V. G. , Yagodkina O. I. 
Published: September 2021

AbstractThe Earth's magnetosphere is mainly a collisionless plasma system with non‐Maxwellian particle distributions, which are often fitted by the kappa function. While the Maxwell distribution function is described by two parameters (density and temperature), the kappa distribution function has three parameters: density, core energy, and the kappa index that characterizes the slope at high energies. In this study, we fitted an ion flux measured by the five Time History of Events and Macroscale Interactions during Substorms satellites in the Earth's magnetosphere during quiet geomagnetic conditions by a single kappa distribution function. The data were constrained to the following regions: from seven Earth Radii (7 ) to the Earth's magnetopause at the dayside, and up to 20 for other magnetic local time sectors. The two‐dimensional spatial distribution of the fitted parameters and their radial dependencies were analyzed. Regions of high and low ‐parameter are selected and their formation is discussed.
Black Carbon Involved Photochemistry Enhances the Formation of Sulfate in the Ambient Atmosphere: Evidence From In Situ Individual Particle Investigation
Authors: Zhang Guohua , Fu Yuzhen , Peng Xiaocong , Sun Wei , Shi Zongbo , Song Wei , Hu Weiwei , Chen Duohong , Lian Xiufeng , Li Lei , Tang Mingjin , Wang Xinming , Bi Xinhui 
Published: September 2021

AbstractMixing state of black carbon (BC) with secondary species has been highlighted as a major uncertainty in assessing its radiative forcing. While recent laboratory simulation has demonstrated that BC could serve as a catalyst to enhance the formation of sulfate, its role in the formation and evolution of secondary aerosols in the real atmosphere remains poorly understood. In the present study, the mixing of BC with sulfate/nitrate in the atmosphere of Guangzhou (China) was directly investigated with a single particle aerosol mass spectrometer (SPAMS). The peak area ratios of sulfate to nitrate (SNRs) for the BC‐containing particles are constantly higher than those of the BC‐free particles (defined as particles with negligible BC signals). Furthermore, the seasonal SNR peak is observed in summer and autumn, and the diurnal peak is found in the afternoon, consistent with the trends of radiation‐related parameters (i.e., solar radiation and temperature), pointing to the BC‐induced photochemical production of sulfate. Such hypothesis is further supported by the multilinear regression and random forest analysis, showing that the variation of SNRs associated with the BC‐containing particles could be well explained (R2 = ∼0.7–0.8) by the radiation‐related parameters (>30% of the variance) and the relative BC content (∼20%) in individual particles, but with limited influence of precursors (SO2/NOx: <5%). Differently, the radiation‐related factors only explain <10% of the SNR variation for the BC‐free particles. These results provide ambient observational evidence pointing to a unique role of BC on the photochemical formation and evolution of sulfate, which merits further quantitative evaluations.
Scaling Laws for Mixed‐Heated Stagnant‐Lid Convection and Application to Europa
Authors: Deschamps Frédéric , Vilella Kenny 
Published: September 2021

AbstractBecause rocks and ices viscosities strongly depend on temperature, planetary mantles and ice shells are often thought to be animated by stagnant‐lid convection. Their dynamics is further impacted by the release of internal heat, either through radioactive isotopes decay or tidal dissipation. Here, we quantify the impact of internal heating on stagnant‐lid convection. We perform numerical simulations of convection combining strongly temperature‐dependent viscosity and mixed (basal and internal) heating in 3D‐Cartesian and spherical geometries, and use these simulations to build scaling laws relating surface heat flux, Φsurf, interior temperature, Tm, and stagnant lid thickness, dlid, to the Rayleigh number, heating rate, H, and top‐to‐bottom viscosity ratio, Δη. These relationships show that Tm increases with H but decreases with Δη, while Φsurf increases with H and Δη. Importantly, they also describe heterogeneously heated systems well, provided that the maximum dissipation occurs in hottest regions. For H larger than a value Hcrit, the bottom heat flux turns negative and the system cools down both at its top and bottom. Two additional interesting results are that (a) while the rigid lid stiffens (its mobility decreases) with increasing H, it also thins; and (b) Hcrit increases with increasing Δη. We then use our scaling laws to assess the impact of tidal heating on Europa's ice shell properties and evolution. Our calculations suggest a shell thickness in the range 20–80 km, depending on viscosity and dissipated power, and show that internal heating has a stronger influence than the presence of impurities in the sub‐surface ocean.
Calibrating Trilobatus sacculifer Na/Ca Ratios From Atlantic Core‐Tops as a Proxy for Sea Surface Salinity
Authors: Watkins Colton S. , Schmidt Matthew W. , Hertzberg Jennifer E. 
Published: September 2021

AbstractRecent studies found a positive correlation between seawater salinity and Na/Ca ratios in foraminiferal calcite, suggesting a potential new paleosalinity proxy (Bertlich et al., 2018, https://doi.org/10.5194/bg-15-5991-2018; Hauzer et al., 2021, https://doi.org/10.1029/2021pa004218; Mezger et al., 2016, https://doi.org/10.1002/2016pa003052; Wit et al., 2013). To test this new proxy in an open‐ocean setting, Na/Ca ratios from the surface‐dwelling planktic foraminifera Trilobatus sacculifer were measured from a suite of nine sediment core‐tops spanning from the North Atlantic subtropical gyre to the South Atlantic subtropical gyre across a salinity range of 1.6. Results show a positive correlation between habitat salinity (HS) and T. sacculifer Na/Ca (Na/Ca (mmol/mol) = 0.516 (HS (±0.17)) – 12.934; R2 = 0.81, p < 0.005). We also find no relationship between T. sacculifer Na/Ca and sample size or habitat temperature, indicating Na/Ca is predominantly controlled by salinity. Additionally, we generate the first downcore record of sea surface salinity (SSS) in the Florida Straits over the last deglaciation based on T. sacculifer Na/Ca variability. Results show agreement between our Na/Ca record and a previously published deglacial δ18Osw record that is also thought to reflect SSS variability from the same core (Schmidt & Lynch‐Stieglitz, 2011, https://doi.org/10.1029/2011PA002157). Both records indicate an abrupt increase in SSS during the Younger Dryas (11.7–12.9 kyr). Converting the Florida Straits T. sacculifer Na/Ca ratios to SSS using our new Atlantic core‐top calibration indicates a maximum salinity change of ∼2.2 across the last deglaciation, in agreement with modeling study estimates of salinity change across this period.
Peripheral inflammation is associated with micro-structural and functional connectivity changes in depression-related brain networks
Authors: Kitzbichler Manfred G. , Aruldass Athina R. , Barker Gareth J. , Wood Tobias C. , Dowell Nicholas G. , Hurley Samuel A. , McLean John , Correia Marta , Clarke Charlotte , Pointon Linda , Cavanagh Jonathan , Cowen Phil , Pariante Carmine , Cercignani Mara ,   Neuroimmunology of Mood Disorders and Alzheimer’s Disease (NIMA) Consortium, Bullmore Edward T. , Harrison Neil A. 
Published: September 2021

AbstractInflammation is associated with depressive symptoms and innate immune mechanisms are likely causal in some cases of major depression. Systemic inflammation also perturbs brain function and microstructure, though how these are related remains unclear. We recruited N = 46 healthy controls, and N = 83 depressed cases stratified by CRP (> 3 mg/L: N = 33; < 3 mg/L: N = 50). All completed clinical assessment, venous blood sampling for C-reactive protein (CRP) assay, and brain magnetic resonance imaging (MRI). Micro-structural MRI parameters including proton density (PD), a measure of tissue water content, were measured at 360 cortical and 16 subcortical regions. Resting-state fMRI time series were correlated to estimate functional connectivity between individual regions, as well as the sum of connectivity (weighted degree) of each region. Multiple tests for regional analysis were controlled by the false discovery rate (FDR = 5%). We found that CRP was significantly associated with PD in precuneus, posterior cingulate cortex (pC/pCC) and medial prefrontal cortex (mPFC); and with functional connectivity between pC/pCC, mPFC and hippocampus. Depression was associated with reduced weighted degree of pC/pCC, mPFC, and other nodes of the default mode network (DMN). Thus CRP-related increases in proton density—a plausible marker of extracellular oedema—and changes in functional connectivity were anatomically co-localised with DMN nodes that also demonstrated significantly reduced hubness in depression. We suggest that effects of peripheral inflammation on DMN node micro-structure and connectivity may mediate inflammatory effects on depression.
A dismantling study on imaginal retraining in overweight or obese women
Authors: Wirtz Janina , Ascone Leonie , Gehlenborg Josefine , Moritz Steffen , Kühn Simone 
Published: September 2021

AbstractImaginal retraining is a variant of approach bias modification and transfers the method into one’s own mind. As the technique contains multiple elements, this pilot study aimed to dismantle which of its components is most efficient in reducing craving for high-calorie food. A total of 113 women were randomly allocated to one out of six conditions containing a short intervention to mentally manipulate a picture displaying high-calorie foods. Four of the interventions involved different combinations of elements of the imaginal retraining technique, while the remaining two conditions comprised thought suppression or merely observing a picture. Participants rated their level of craving, as well as three pictures containing healthy and unhealthy foods regarding their pleasantness before and after the interventions took place. Within-group changes were assessed with paired t-tests (in case of non-normal data Wilcoxon paired t-tests) and between-group differences with one-way ANOVAs (non-parametric Kruskal–Wallis tests). A trend level reduction in craving was found in the imaginal retraining condition with and without a movement. A post hoc analysis of both conditions joint together showed a statistically significant reduction in craving. In addition, positive picture appraisal for unhealthy foods was significantly reduced in both imaginal retraining conditions (with and without movement) with medium to large effect sizes. This study demonstrated that imaginal retraining with an arm movement can reduce craving and picture appraisal for high-calorie foods significantly in a one-time application. It is a promising technique to reduce appraisal for unhealthy high-calorie foods. Future studies should repeat the experiment in situations of high craving and allow for a personalized selection of stimuli.
Alpha-Synuclein defects autophagy by impairing SNAP29-mediated autophagosome-lysosome fusion
Authors: Tang Qilin , Gao Pan , Arzberger Thomas , Höllerhage Matthias , Herms Jochen , Höglinger Günter , Koeglsperger Thomas 
Published: September 2021

AbstractDopaminergic (DA) cell death in Parkinson’s disease (PD) is associated with the gradual appearance of neuronal protein aggregates termed Lewy bodies (LBs) that are comprised of vesicular membrane structures and dysmorphic organelles in conjunction with the protein alpha-Synuclein (α-Syn). Although the exact mechanism of neuronal aggregate formation and death remains elusive, recent research suggests α-Syn-mediated alterations in the lysosomal degradation of aggregated proteins and organelles – a process termed autophagy. Here, we used a combination of molecular biology and immunochemistry to investigate the effect of α-Syn on autophagy turnover in cultured human DA neurons and in human post-mortem brain tissue. We found α-Syn overexpression to reduce autophagy turnover by compromising the fusion of autophagosomes with lysosomes, thus leading to a decrease in the formation of autolysosomes. In accord with a compensatory increase in the plasma membrane fusion of autophagosomes, α-Syn enhanced the number of extracellular vesicles (EV) and the abundance of autophagy-associated proteins in these EVs. Mechanistically, α-Syn decreased the abundance of the v-SNARE protein SNAP29, a member of the SNARE complex mediating autophagolysosome fusion. In line, SNAP29 knockdown mimicked the effect of α-Syn on autophagy whereas SNAP29 co-expression reversed the α-Syn-induced changes on autophagy turnover and EV release and ameliorated DA neuronal cell death. In accord with our results from cultured neurons, we found a stage-dependent reduction of SNAP29 in SNc DA neurons from human post-mortem brain tissue of Lewy body pathology (LBP) cases. In summary, our results thus demonstrate a previously unknown effect of α-Syn on intracellular autophagy-associated SNARE proteins and, as a consequence, a reduced autolysosome fusion. As such, our findings will therefore support the investigation of autophagy-associated pathological changes in PD
TKT maintains intestinal ATP production and inhibits apoptosis-induced colitis
Authors: Tian Na , Hu Lei , Lu Ying , Tong Lingfeng , Feng Ming , Liu Qi , Li Yakui , Zhu Yemin , Wu Lifang , Ji Yingning , Zhang Ping , Xu Tianle , Tong Xuemei 
Published: September 2021

AbstractInflammatory bowel disease (IBD) has a close association with transketolase (TKT) that links glycolysis and the pentose phosphate pathway (PPP). However, how TKT functions in the intestinal epithelium remains to be elucidated. To address this question, we specifically delete TKT in intestinal epithelial cells (IECs). IEC TKT-deficient mice are growth retarded and suffer from spontaneous colitis. TKT ablation brings about striking alterations of the intestine, including extensive mucosal erosion, aberrant tight junctions, impaired barrier function, and increased inflammatory cell infiltration. Mechanistically, TKT deficiency significantly accumulates PPP metabolites and decreases glycolytic metabolites, thereby reducing ATP production, which results in excessive apoptosis and defective intestinal barrier. Therefore, our data demonstrate that TKT serves as an essential guardian of intestinal integrity and barrier function as well as a potential therapeutic target for intestinal disorders.
The Arabidopsis MIK2 receptor elicits immunity by sensing a conserved signature from phytocytokines and microbes
Authors: Hou Shuguo , Liu Derui , Huang Shijia , Luo Dexian , Liu Zunyong , Xiang Qingyuan , Wang Ping , Mu Ruimin , Han Zhifu , Chen Sixue , Chai Jijie , Shan Libo , He Ping 
Published: September 2021

AbstractSessile plants encode a large number of small peptides and cell surface-resident receptor kinases, most of which have unknown functions. Here, we report that the Arabidopsis receptor kinase MALE DISCOVERER 1-INTERACTING RECEPTOR-LIKE KINASE 2 (MIK2) recognizes the conserved signature motif of SERINE-RICH ENDOGENOUS PEPTIDEs (SCOOPs) from Brassicaceae plants as well as proteins present in fungal Fusarium spp. and bacterial Comamonadaceae, and elicits various immune responses. SCOOP signature peptides trigger immune responses and altered root development in a MIK2-dependent manner with a sub-nanomolar sensitivity. SCOOP12 directly binds to the extracellular leucine-rich repeat domain of MIK2 in vivo and in vitro, indicating that MIK2 is the receptor of SCOOP peptides. Perception of SCOOP peptides induces the association of MIK2 and the coreceptors SOMATIC EMBRYOGENESIS RECEPTOR KINASE 3 (SERK3) and SERK4 and relays the signaling through the cytosolic receptor-like kinases BOTRYTIS-INDUCED KINASE 1 (BIK1) and AVRPPHB SUSCEPTIBLE1 (PBS1)-LIKE 1 (PBL1). Our study identifies a plant receptor that bears a dual role in sensing the conserved peptide motif from phytocytokines and microbial proteins via a convergent signaling relay to ensure a robust immune response.
Structural basis of RNA polymerase inhibition by viral and host factors
Authors: Pilotto Simona , Fouqueau Thomas , Lukoyanova Natalya , Sheppard Carol , Lucas-Staat Soizick , Díaz-Santín Luis Miguel , Matelska Dorota , Prangishvili David , Cheung Alan C. M. , Werner Finn 
Published: September 2021

AbstractRNA polymerase inhibition plays an important role in the regulation of transcription in response to environmental changes and in the virus-host relationship. Here we present the high-resolution structures of two such RNAP-inhibitor complexes that provide the structural bases underlying RNAP inhibition in archaea. The Acidianus two-tailed virus encodes the RIP factor that binds inside the DNA-binding channel of RNAP, inhibiting transcription by occlusion of binding sites for nucleic acid and the transcription initiation factor TFB. Infection with the Sulfolobus Turreted Icosahedral Virus induces the expression of the host factor TFS4, which binds in the RNAP funnel similarly to eukaryotic transcript cleavage factors. However, TFS4 allosterically induces a widening of the DNA-binding channel which disrupts trigger loop and bridge helix motifs. Importantly, the conformational changes induced by TFS4 are closely related to inactivated states of RNAP in other domains of life indicating a deep evolutionary conservation of allosteric RNAP inhibition.
Demonstration of valley anisotropy utilized to enhance the thermoelectric power factor
Authors: Li Airan , Hu Chaoliang , He Bin , Yao Mengyu , Fu Chenguang , Wang Yuechu , Zhao Xinbing , Felser Claudia , Zhu Tiejun 
Published: September 2021

AbstractValley anisotropy is a favorable electronic structure feature that could be utilized for good thermoelectric performance. Here, taking advantage of the single anisotropic Fermi pocket in p-type Mg3Sb2, a feasible strategy utilizing the valley anisotropy to enhance the thermoelectric power factor is demonstrated by synergistic studies on both single crystals and textured polycrystalline samples. Compared to the heavy-band direction, a higher carrier mobility by a factor of 3 is observed along the light-band direction, while the Seebeck coefficient remains similar. Together with lower lattice thermal conductivity, an increased room-temperature zT by a factor of 3.6 is found. Moreover, the first-principles calculations of 66 isostructural Zintl phase compounds are conducted and 9 of them are screened out displaying a pz-orbital-dominated valence band, similar to Mg3Sb2. In this work, we experimentally demonstrate that valley anisotropy is an effective strategy for the enhancement of thermoelectric performance in materials with anisotropic Fermi pockets.
Reactive wear protection through strong and deformable oxide nanocomposite surfaces
Authors: Liu Chang , Li Zhiming , Lu Wenjun , Bao Yan , Xia Wenzhen , Wu Xiaoxiang , Zhao Huan , Gault Baptiste , Liu Chenglong , Herbig Michael , Fischer Alfons , Dehm Gerhard , Wu Ge , Raabe Dierk 
Published: September 2021

AbstractWear-related energy and material loss cost over 2500 Billion Euro per year. Traditional wisdom suggests that high-strength materials reveal low wear rates, yet, their plastic deformation mechanisms also influence their wear performance. High strength and homogeneous deformation behavior, which allow accommodating plastic strain without cracking or localized brittle fracture, are crucial for developing wear-resistant metals. Here, we present an approach to achieve superior wear resistance via in-situ formation of a strong and deformable oxide nanocomposite surface during wear, by reaction of the metal surface with its oxidative environment, a principle that we refer to as ‘reactive wear protection’. We design a TiNbZr-Ag alloy that forms an amorphous-crystalline oxidic nanocomposite surface layer upon dry sliding. The strong (2.4 GPa yield strength) and deformable (homogeneous deformation to 20% strain) nanocomposite surface reduces the wear rate of the TiNbZr-Ag alloy by an order of magnitude. The reactive wear protection strategy offers a pathway for designing ultra-wear resistant alloys, where otherwise brittle oxides are turned to be strong and deformable for improving wear resistance.
Two-dimensional molybdenum carbide 2D-Mo2C as a superior catalyst for CO2 hydrogenation
Authors: Zhou Hui , Chen Zixuan , Kountoupi Evgenia , Tsoukalou Athanasia , Abdala Paula M. , Florian Pierre , Fedorov Alexey , Müller Christoph R. 
Published: September 2021

AbstractEarly transitional metal carbides are promising catalysts for hydrogenation of CO2. Here, a two-dimensional (2D) multilayered 2D-Mo2C material is prepared from Mo2CTx of the MXene family. Surface termination groups Tx (O, OH, and F) are reductively de-functionalized in Mo2CTx (500 °C, pure H2) avoiding the formation of a 3D carbide structure. CO2 hydrogenation studies show that the activity and product selectivity (CO, CH4, C2–C5 alkanes, methanol, and dimethyl ether) of Mo2CTx and 2D-Mo2C are controlled by the surface coverage of Tx groups that are tunable by the H2 pretreatment conditions. 2D-Mo2C contains no Tx groups and outperforms Mo2CTx, β-Mo2C, or the industrial Cu-ZnO-Al2O3 catalyst in CO2 hydrogenation (evaluated by CO weight time yield at 430 °C and 1 bar). We show that the lack of surface termination groups drives the selectivity and activity of Mo-terminated carbidic surfaces in CO2 hydrogenation.