bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructural Characteristics of DHA-Induced Pyroptosis
Authors: Herr Deron R. , Yam Ting Yu Amelia , Tan Wan Shun Daniel , Koh Sally Shuxian , Wong Wai Shiu Fred , Ong Wei-Yi , Chayaburakul Kanokporn
Published: January 2020

Microglial cells are resident macrophages of the central nervous system (CNS) that respond to bioactive lipids such as docosahexaenoic acid (DHA). Low micromolar concentrations of DHA typically promote anti-inflammatory functions of microglia, but higher concentrations result in a form of pro-inflammatory programmed cell death known as pyroptosis. This study used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to investigate the morphological characteristics of pyroptosis in BV-2 microglial cells following exposure to 200 µM DHA. Vehicle-treated cells are characterized by extended processes, spine-like projections or 0.4 to 5.2 µm in length, and numerous extracellular vesicles (EVs) tethered to the surface of the plasma membrane. In contrast to vehicle-treated cells, gross abnormalities are observed after treating cells with 200 µM DHA for 4 h. These include the appearance of numerous pits or pores of varying sizes across the cell surface, structural collapse and flattening of the cell shape. Moreover, EVs and spines were lost following DHA treatment, possibly due to release from the cell surface. The membrane pores appear after DHA treatment initially measured ~ 30 nm, consistent with the previously reported gasdermin D (GSDMD) pore complexes. Complete collapse of cytoplasmic organization and loss of nuclear envelope integrity were also observed in DHA-treated cells. These processes are morphologically distinct from the changes that occur during cisplatin-induced apoptosis, such as the appearance of apoptotic bodies and tightly packed organelles, and the maintenance of EVs and nuclear envelope integrity. Cumulatively, this study provides a systematic description of the ultrastructural characteristics of DHA-induced pyroptosis, including distinguishing features that differentiate this process from apoptosis.
Label-free quantitative identification of abnormally ubiquitinated proteins as useful biomarkers for human lung squamous cell carcinomas
Authors: Lu Miaolong , Chen Wei , Zhuang Wei , Zhan Xianquan
Published: January 2020

Background

Ubiquitination is an important molecular event in lung squamous cell carcinoma (LSCC), which currently is mainly studied in nonsmall cell lung carcinoma cell models but lacking of ubiquitination studies on LSCC tissues. Here, we presented the ubiquitinated protein profiles of LSCC tissues to explore ubiquitination-involved molecular network alterations and identify abnormally ubiquitinated proteins as useful biomarkers for predictive, preventive, and personalized medicine (PPPM) in LSCC.

Methods

Anti-ubiquitin antibody-based enrichment coupled with LC-MS/MS was used to identify differentially ubiquitinated proteins (DUPs) between LSCC and control tissues, followed by integrative omics analyses to identify abnormally ubiquitinated protein biomarkers for LSCC.

Results

Totally, 400 DUPs with 654 ubiquitination sites were identified,, and motifs A-X (1/2/3)-K* were prone to be ubiquitinated in LSCC tissues. Those DUPs were involved in multiple molecular network systems, including the ubiquitin–proteasome system (UPS), cell metabolism, cell adhesion, and signal transduction. Totally, 44 hub molecules were revealed by protein–protein interaction network analysis, followed by survival analysis in TCGA database (494 LSCC patients and 20,530 genes) to obtain 18 prognosis-related mRNAs, of which the highly expressed mRNAs VIM and IGF1R were correlated with poorer prognosis, while the highly expressed mRNA ABCC1 was correlated with better prognosis. VIM-encoded protein vimentin and ABCC1-encoded protein MRP1 were increased in LSCC, which were all associated with poor prognosis. Proteasome-inhibited experiments demonstrated that vimentin and MRP1 were degraded through UPS. Quantitative ubiquitinomics found ubiquitination level was decreased in vimentin and increased in MRP1 in LSCC. These findings showed that the increased vimentin in LSCC might be derived from its decreased ubiquitination level and that the increased MRP1 in LSCC might be derived from its protein synthesis > degradation. GSEA and co-expression gene analyses revealed that VIM and MRP1 were involved in multiple crucial biological processes and pathways. Further, TRIM2 and NEDD4L were predicted as E3 ligases to regulate ubiquitination of vimentin and MRP1, respectively.

Conclusion

These findings revealed ubiquitinomic variations and molecular network alterations in LSCC, which is in combination with multiomics analysis to identify ubiquitination-related biomarkers for in-depth insight into the molecular mechanism and therapeutic targets and for prediction, diagnosis, and prognostic assessment of LSCC.
Application of TiO2 and ZnO nanoparticles immobilized on clay in wastewater treatment: a review
Authors: Mustapha S. , Ndamitso M. M. , Abdulkareem A. S. , Tijani J. O. , Shuaib D. T. , Ajala A. O. , Mohammed A. K.
Published: January 2020

Increase in industrial and anthropogenic activities leads to a decline in water quality. This necessitates the need for the removal of contaminants from industrial and domestic wastewater. Clay minerals are naturally abundant and non-toxic materials that found to be useful for remediation of emerging contaminants from wastewater. This review paper presents an insight into clay, the simplest material (in solgel techniques) for the synthesis of TiO2and ZnO, mechanisms of their reactions, analytical techniques used for characterizations, and their nanocomposites for wastewater treatment. Nanomaterials, such as nanoclay, titanium, and zinc oxide, have offered the opportunities of sequestering variety of pollutants in wastewater. TiO2and ZnO anchored on clay have been found to be good promising sequesters and have been explored for wastewater remediation via nanotechnology. This water treatment method includes adsorption/absorption, photocatalysis, and microbial disinfection. These nanocomposites provide more active surface sites and reduce the agglomeration of the nanoparticles, but leaching has been their shortcomings. To overcome this, the filtration technique may become significant for the removal and avoidance of fouling of wastewater. This can be achieved through the fabrication of nano-based filters using the nanocomposites.
Progressive effects of single-nucleotide polymorphisms on 16 phenotypic traits based on longitudinal data
Authors: Li Donghe , Kang Hahn , Lee Sanghun , Won Sungho
Published: January 2020

Background

There are many research studies have estimated the heritability of phenotypic traits, but few have considered longitudinal changes in several phenotypic traits together.

Objective

To evaluate the progressive effect of single nucleotide polymorphisms (SNPs) on prominent health-related phenotypic traits by determining SNP-based heritability ($$h_{snp}^{2}$$hsnp2) using longitudinal data.

Methods

Sixteen phenotypic traits associated with major health indices were observed biennially for 6843 individuals with 10-year follow-up in a Korean community-based cohort. Average SNP heritability and longitudinal changes in the total period were estimated using a two-stage model. Average and periodic differences for each subject were considered responses to estimate SNP heritability. Furthermore, a genome-wide association study (GWAS) was performed for significant SNPs.

Results

Each SNP heritability for the phenotypic mean of all sixteen traits through 6 periods (baseline and five follow-ups) were significant. Gradually, the forced vital capacity in one second (FEV1) reflected the only significant SNP heritability among longitudinal changes at a false discovery rate (FDR)-adjusted 0.05 significance level ($$h_{snp}^{2} = 0.171$$hsnp2=0.171, FDR = 0.0012). On estimating chromosomal heritability, chromosome 2 displayed the highest heritability upon periodic changes in FEV1. SNPs including rs2272402 and rs7209788 displayed a genome-wide significant association with longitudinal changes in FEV1 (P = 1.22 × 10−8 for rs2272402 and P = 3.36 × 10−7 for rs7209788). De novo variants including rs4922117 (near LPL, P = 2.13 × 10−15) of log-transformed high-density lipoprotein (HDL) ratios and rs2335418 (near HMGCR, P = 3.2 $$\times$$× 10−9) of low-density lipoprotein were detected on GWAS.

Conclusion

Significant genetic effects on longitudinal changes in FEV1 among the middle-aged general population and chromosome 2 account for most of the genetic variance.
New triazepine carboxylate derivatives: correlation between corrosion inhibition property and chemical structure
Authors: Alaoui K. , El Kacimi Y. , Galai M. , Serrar H. , Touir R. , Kaya S. , Kaya C. , Ebn Touhami M.
Published: January 2020

In this investigation, attempts have been made to study the corrosion inhibition properties of three new triazepine carboxylate compounds for mild steel in 1.0 M hydrochloric acid medium. The evaluation was carried out using mass loss, electrochemical impedance spectroscopy and polarization curves measurement. Impedance diagrams and Bode plots for uninhibited and inhibited systems were analyzed using Zview program. The fitted data observed trails in nearly the same pattern as the experimental results. It is showed that triazepine carboxylate compounds are very good inhibitors for mild steel corrosion in 1.0 M hydrochloric acid medium which act as mixed-type inhibitors. So, the inhibition efficiency was increased with inhibitor concentration in the order Cl–Me–CN > Me–CN > Cl–Me–CO2Et which depended on their molecular structures. Electrochemical impedance spectroscopy showed that all compounds act by the formation of a protective film at the metal surface. Surface analyses via SEM and Optical 3D profilometry were used to investigate the morphology of the steels before and after immersion in 1.0 M HCl solution containing inhibitors. The correspondence between inhibition property and molecular structure of the triazepine carboxylate compounds was investigated, using density functional theory (DFT). Experimental and DFT study was further supported by molecular dynamic simulations study.
How electrostatic and non-electrostatic interactions play a role in water wettability of possible nanostructure surfaces
Authors: Novin Nima , Shameli Abolghasem , Balali Ebrahim , Zomorodbakhsh Shahab
Published: January 2020

The present paper investigated the effects of the electrostatic and non-electrostatic interactions on the water wettability of a surface. Based on this aim, examinations are performed on the molybdenum disulfide (MoS2) as possible nanostructure surface. The results obtained through calculating the water contact angle on the MoS2 surface indicate which this surface is a weak hydrophobic substrate. The present simulations illustrate that the electrostatic interactions have little impact on the wettability amount of the MoS2 substrate. However, the molybdenum disulfide is composed of two charged parts with significant values. In addition, it is observed that the relation between density, van der Waals and electrostatic interactions is different from each other. It have been observed that the van der Waals interactions have direct relationship with water density while there is not anything between the electrostatic interactions and water density peak. The Obtained results via simulation demonstrate that the effectiveness of electrostatic interactions on the wettability depends on the sigma in the Lennard–Jones equation. In the other words, the role of electrostatic and van der Waals interactions on the wettability are not indissociable from each other and this method is sufficient in nanostructure systems.

Graphic abstract
Rate-, state-, and pressure-dependent friction model based on the elastoplastic theory
Authors: Ozaki Shingo , Matsuura Takeru , Maegawa Satoru
Published: January 2020

Adhesion is one of essences with respect to rubber friction because the magnitude of the friction force is closely related to the magnitude of adhesion on a real contact area. However, the real contact area during sliding depends on the state and history of the contact surface. Therefore, the friction force occasionally exhibits rate-, state-, and pressure dependency. In this study, to rationally describe friction and simulate boundary value problems, a rate-, state-, and pressure-dependent friction model based on the elastoplastic theory was formulated. First, the evolution law for the friction coefficient was prescribed. Next, a nonlinear sliding surface (frictional criterion) was adopted, and several other evolution laws for internal state variables were prescribed. Subsequently, the typical response characteristics of the proposed friction model were demonstrated, and its validity was verified by comparing the obtained results with those of experiments conducted considering the contact surface between a rough rubber hemisphere and smooth acrylic plate.
Microstress cycle and contact fatigue of spiral bevel gears by rolling-sliding of asperity contact
Authors: Cao Wei , Ren Si , Pu Wei , Xiao Ke
Published: January 2020

The rolling contact fatigue (RCF) model is commonly used to predict the contact fatigue life when the sliding is insignificant in contact surfaces. However, many studies reveal that the sliding, compared to the rolling state, can lead to a considerable reduction of the fatigue life and an excessive increase of the pitting area, which result from the microscopic stress cycle growth caused by the sliding of the asperity contact. This suggests that fatigue life in the rolling-sliding condition can be overestimated based only on the RCF model. The rubbing surfaces of spiral bevel gears are subject to typical rolling-sliding motion. This paper aims to study the mechanism of the micro stress cycle along the meshing path and provide a reasonable method for predicting the fatigue life in spiral bevel gears. The microscopic stress cycle equation is derived with the consideration of gear meshing parameters. The combination of the RCF model and asperity stress cycle is developed to calculate the fatigue life in spiral bevel gears. We find that the contact fatigue life decreases significantly compared with that obtained from the RCF model. There is strong evidence that the microscopic stress cycle is remarkably increased by the rolling-sliding motion of the asperity contact, which is consistent with the experimental data in previous literature. In addition, the fatigue life under different assembling misalignments are investigated and the results demonstrate the important role of misalignments on fatigue life.
Hierarchical Porous RGO/PEDOT/PANI Hybrid for Planar/Linear Supercapacitor with Outstanding Flexibility and Stability
Authors: Liu Fuwei , Xie Luoyuan , Wang Li , Chen Wei , Wei Wei , Chen Xian , Luo Shaojuan , Dong Lei , Dai Qilin , Huang Yang , Wang Lei
Published: January 2020

Many hybrid electrodes for supercapacitors (SCs) are a reckless combination without proper structural design that keeps them from fulfilling their potential. Herein, we design a reduced graphene oxide/poly(3,4-ethylenedioxythiophene)/polyaniline (RGO/PEDOT/PANI) hybrid with hierarchical and porous structure for high-performance SCs, where components fully harness their advantages, forming an interconnected and conductive framework with substantial reactive sites.Thus, this hybrid achieves a high capacitance of 535 F g−1 along with good rate capability and cyclability. The planar SC based on this hybrid deliver an energy density of 26.89 Wh kg−1 at a power density of 800 W kg−1. The linear SC developed via modifying a cotton yarn with the hybrid exhibits good flexibility and structural stability, which operates normally after arbitrary deformations. This work provides a beneficial reference for developing SCs.
Graphitic Carbon Quantum Dots Modified Nickel Cobalt Sulfide as Cathode Materials for Alkaline Aqueous Batteries
Authors: Zhu Yirong , Li Jingying , Yun Xiaoru , Zhao Ganggang , Ge Peng , Zou Guoqiang , Liu Yong , Hou Hongshuai , Ji Xiaobo
Published: January 2020

Carbon quantum dots (CQDs) as a new class of emerging materials have gradually drawn researchers’ concern in recent years. In this work, the graphitic CQDs are prepared through a scalable approach, achieving a high yield with more than 50%. The obtained CQDs are further used as structure-directing and conductive agents to synthesize novel N,S-CQDs/NiCo2S4 composite cathode materials, manifesting the enhanced electrochemical properties resulted from the synergistic effect of highly conductive N,S-codoped CQDs offering fast electronic transport and unique micro-/nanostructured NiCo2S4 microspheres with Faradaic redox characteristic contributing large capacity. Moreover, the nitrogen-doped reduced graphene oxide (N-rGO)/Fe2O3 composite anode materials exhibit ultrahigh specific capacity as well as significantly improved rate property and cycle performance originating from the high-capacity prism-like Fe2O3 hexahedrons tightly wrapped by highly conductive N-rGO. A novel alkaline aqueous battery assembled by these materials displays a specific energy (50.2 Wh kg−1), ultrahigh specific power (9.7 kW kg−1) and excellent cycling performance with 91.5% of capacity retention at 3 A g−1 for 5000 cycles. The present research offers a valuable guidance for the exploitation of advanced energy storage devices by the rational design and selection of battery/capacitive composite materials.
The Role of Palliative Care in Reducing Symptoms and Improving Quality of Life for Patients with Idiopathic Pulmonary Fibrosis: A Review
Authors: Zou Richard H. , Kass Daniel J. , Gibson Kevin F. , Lindell Kathleen O.
Published: January 2020

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease with a median survival of 3–4 years from time of initial diagnosis, similar to the time course of many malignancies. A hallmark of IPF is its unpredictable disease course, ranging from long periods of clinical stability to acute exacerbations with rapid decompensation. As the disease progresses, patients with chronic cough and progressive exertional dyspnea become oxygen dependent. They may experience significant distress due to concurrent depression, anxiety, and fatigue, which often lead to increased symptom burden and decreased quality of life. Despite these complications, palliative care is an underutilized, and often underappreciated, resource before end-of-life care in this population. While there is growing recognition about early palliative care in IPF, current data suggest referral patterns vary widely based on institutional practices. In addition to focusing on symptom management, there is emphasis on supplemental oxygen use, pulmonary rehabilitation, quality of life, and end-of-life care. Importantly, increased use of support groups and national foundation forums have served as venues for further disease education, communication, and advanced care planning outside of the hospital settings. The purpose of this review article is to discuss the clinical features of IPF, the role of palliative care in chronic disease management, current data supporting benefits of palliative care in IPF, its role in symptom management, and practices to help patients and their caregivers achieve their best quality of life.
Effect of interfacial drag force model on code prediction for upward adiabatic two-phase bubbly flow in vertical channels
Authors: Hibiki Takashi , Ozaki Tetsuhiro
Published: January 2020

Accurate modeling of the interfacial drag force is one of the keys to predicting thermo-fluid parameters using one-dimensional nuclear thermal-hydraulic system analysis code architected through the two-fluid model. The interfacial drag force appears in the interfacial momentum transfer term and governs the velocity slip or the relative velocity between gas and liquid phases. The most straightforward method to model the interfacial drag force is to model the force through the drag law (drag law approach). A drag coefficient and interfacial area concentration should be given to close the interfacial drag force model. Among them, the modeling of the interfacial area concentration has been one of the weakest links in the interfacial drag force modeling due to the lack of reliable data covering a wide test condition including prototypic nuclear reactor conditions and lack of physically sound interfacial area model. To avoid a considerable uncertainty in the prediction of the interfacial area concentration, Andersen and Chu (1982) proposed the interfacial drag force model using the drift-flux parameters (Andersen approach). The Andersen approach is practical for the simulation of a slow transient flow and a steady flow. Major system analysis codes such as USNRC TRACE have adopted the Andersen approach in the interfacial drag force modeling. Some attempts to improve the code performance have been considered using the drag law approach with the interfacial area transport equation. The dynamic modeling of the interfacial area concentration has the potential to improve the prediction accuracy of the interfacial area concentration in a transient flow and developing flow. Due to the importance of the improved interfacial drag force modeling, the implementation and evaluation of the interfacial area transport equation in USNRC TRACE code has been performed by Talley et al. (2011, 2013). The study claimed that the introduction of the interfacial area transport equation into the TRACE code improved the code performance in an adiabatic bubbly flow analysis significantly. The present study assessed the code calculation made by Talley et al. (2011) and identified several issues in the code calculation results. The present study analytically demonstrated that the drag law approach became identical with the Andersen approach for the distorted particle regime (or a major bubble shape regime in bubbly flow) due to the balancing-out of the interfacial area concentration (or bubble size) in the numerator and denominator of the interfacial drag force formulation. The code calculation using TRAC code endorsed the analytical assessment of the insignificant or no merit of the interfacial area transport equation in the code performance of the adiabatic bubbly flow analysis. The present study also pointed out the inconsistency of the code calculation made by Talley et al. (2011).
Concentration of meropenem in patients with sepsis and acute kidney injury before and after initiation of continuous renal replacement therapy: a prospective observational trial
Authors: Nowak-Kózka Ilona , Polok Kamil J. , Górka Jacek , Fronczek Jakub , Gielicz Anna , Seczyńska Bożena , Czuczwar Mirosław , Kudliński Bartosz , Szczeklik Wojciech
Published: January 2020

Background

The effect of renal replacement therapy on drug concentrations in patients with sepsis has not been fully elucidated because the pharmacokinetic properties of many antimicrobials are influenced by both pathophysiological and treatment-related factors. The aim of this study was to determine meropenem concentrations in patients with sepsis before and after the initiation of continuous venovenous hemodialysis with regional citrate anticoagulation (RCA-CVVHD).

Methods

The study included 15 critically ill patients undergoing RCA-CVVHD due to sepsis-induced acute kidney injury. All participants received 2 g of meropenem every 8 h in a prolonged infusion lasting 3 h. Meropenem concentrations were measured in blood plasma using high-performance liquid chromatography coupled with tandem mass spectrometry. Blood samples were obtained at six-time points prior to and at six-time points after introducing RCA-CVVHD.

Results

The median APACHE IV and SOFA scores on admission were 118 points (interquartile range [IQR] 97–134 points) and 19.5 points (IQR 18–21 points), respectively. There were no significant differences in the plasma concentrations of meropenem measured directly before RCA-CVVHD and during the first 450 min of the procedure. The drug concentration reached its peak 2 h after initiating the infusion and then steadily declined.

Conclusions

The concentration of high-dose meropenem (2 g every 8 h) administered in a prolonged infusion was similar before and after the introduction of RCA-CVVHD in patients with sepsis who developed acute kidney injury.
Maximum Southwest Greenland Ice Sheet Recession in the Early Holocene
Authors: Lesnek A. J. , Briner J. P. , Young N. E. , Cuzzone J. K.
Published: January 2020

Establishing the timing of maximum Holocene warmth in the Arctic is critical for understanding global climate system response to external forcing. In Greenland, challenges in obtaining climate records that span the full Holocene have hampered efforts to robustly identify when the Holocene Thermal Maximum occurred. Reconstructing land‐based ice sheet history can fill this gap because these ice sheet regions respond sensitively to summer temperature. We synthesize new and published 10Be and 14C ages from southwest Greenland to map Greenland ice sheet margin positions from 12 to 7 ka and calculate retreat rates from 12 to 0 ka. We found that maximum Greenland ice sheet recession occurred between ~10.4 and 9.1 ka. Our reconstruction suggests that summer air temperatures in southwest Greenland were highest from ~10.4 to 9.1 ka, providing support for an early regional Holocene Thermal Maximum. These results can serve as benchmarks for comparison with ice sheet and climate model simulations.
Identifying Active Kelvin–Helmholtz Vortices on Saturn's Magnetopause Boundary
Authors: Burkholder B. L. , Delamere P. A. , Johnson J. R. , Ng C.‐S.
Published: January 2020

For
Cassini magnetopause encounters, we analyse plasma and magnetic fields. The boundary can be unstable to the Kelvin–Helmholtz instability (KHI), which can drive large‐scale flows identifiable in plasma measurements. Bulk flow reversed from the expected direction near the magnetopause can indicate vorticity associated with active KH, and events are found dominantly in the dawn–subsolar region. KHIs are also responsible for magnetic field fluctuations, and hybrid simulations indicate heating, and transport is significant in an actively growing vortex. Cassini observations are filtered for disturbed magnetic fields near the magnetopause, similar to the signatures from hybrid simulations, with significant fluctuation and current sheet crossings. We also find that these occur most frequently in the dawn–subsolar region. A turbulent heating rate density and mass diffusion coefficient are calculated for these disturbed events and compared with the hybrid simulation to test whether enhanced values for these quantities can identify active KH events.
An Assessment of PBL Heights and Low Cloud Profiles in CAM5 and CAM5‐CLUBB Over the Southeast Pacific Using Satellite Observations
Authors: Kubar Terence L. , Xie Feiqin , Ao Chi O. , Adhikari Loknath
Published: January 2020

Instantaneous satellite cloud top height (CTH) data from Moderate Resolution Imaging Spectroradiometer and Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation, as well as planetary boundary layer (PBL) heights corresponding to the minimum refractivity gradient (PBLHN) from GPS radio occultation over the Southeast Pacific, are jointly used for the first time to assess the ability of three versions of National Center for Atmospheric Research Community Atmosphere Model 5 (CAM5) to simulate low‐level cloud extent and boundary layer heights. Observed CTH and PBLHN match most closely in the stratocumulus and stratocumulus‐to‐cumulus transition region, but CTH becomes lower than PBLHN since not all trade cumulus clouds reach the inversion. Simulated CTH and PBLHN are too shallow, but clouds with a new subgrid low cloud parameterization, Cloud Layers Unified by Binormals (CAM5‐CLUBB), have a reduced bias, with the CTH‐PBLHN distribution from Hi‐Res CAM5‐CLUBB, the most similar to observations. For PBLHN > 2.7 km, the base CAM5 model shows a bimodal cloud structure and surface‐to‐500 hPa ascent not seen in observations and European Centre for Medium‐Range Weather Forecasts Re analysis Interim data.
Variability in Direct and Diffuse Solar Radiation Across China From 1958 to 2017
Authors: He Yanyi , Wang Kaicun
Published: January 2020

Long‐term variability of direct and diffuse solar radiation (Rdir and Rdif) is essential for climate change study. However, Rdir and Rdif observations suffer from low spatiotemporal coverage and inhomogeneity. This study improved hybrid models to calculate Rdir and Rdif from sunshine duration and meteorological data at ~2,000 stations from 1958 to 2017 over China and demonstrated their reliability. We identified that Rdir observations show a spurious steep downtrend before 1990 due to the sensitivity drift of the measuring instruments, implying an overestimation of global dimming. Long‐term trends and spatiotemporal details in Rdir and Rdif were also revealed. From 1958 to 1989, our results show that Rdir displays a significant downtrend (−3.52 W m−2 per decade), whereas Rdif shows a significant increasing trend (0.84 W m−2 per decade), especially over the North China Plain. From 1990 to 2017, Rdir decreases nonsignificantly by −0.47 W m−2 per decade but Rdif shows a slight decline of −0.28 W m−2 per decade.
Assessing Energy Budget of Laboratory Fault Slip Using Rotary Shear Experiments and Micro‐Computed Tomography
Authors: Zhao Qi , Glaser Steven D. , Tisato Nicola , Grasselli Giovanni
Published: January 2020

Quantitative assessment of the energy budget of earthquake events is one of the key aspects for understanding the physics of earthquakes. Investigation of laboratory fault slips under controlled conditions can provide insights on this important aspect of the natural and induced earthquakes. We conducted a rotary shear experiment under X‐ray micro‐computed tomography, which allowed in situ and operando measurement of macroscopic stresses and imaging of the newly formed fractures inside the sample. We estimate each component of the energy budget and found that friction energy loss (EF), fracture energy (EG), and radiated energy (ER) account for 70.16%, 15.68%, and 14.15% of the total energy budget, respectively. Quantitative analysis of the micro‐computed tomography images indicates that the energy consumed by creating slip‐induced off‐fault fractures (
) accounts for only 0.3% of the total energy, less than 2% of the total EG.
Pacific Modulation of the North Atlantic Storm Track Response to Sudden Stratospheric Warming Events
Authors: Afargan‐Gerstman Hilla , Domeisen Daniela I. V.
Published: January 2020

Sudden stratospheric warming (SSW) events have been suggested to be followed by a surface impact, though this response varies between events. Using reanalysis data, we identify two types of tropospheric responses to SSWs: Two thirds of the SSW events are dominated by a zonally symmetric tropospheric response with an equatorward shift of the jet in the Atlantic, consistent with the canonical SSW response in the form of a negative signature of the North Atlantic Oscillation. For the remaining third of SSW events, a zonally asymmetric response is found, associated with a poleward shift of the jet in the Atlantic. The Pacific is found to contribute to the sign of the North Atlantic response, as synoptic wave propagation from the Eastern Pacific links the Pacific and Atlantic storm tracks for both equatorward and poleward jet responses.
A New Substorm Onset Mechanism: Increasingly Parallel Pressure Anisotropic Ballooning
Authors: Oberhagemann L. R. , Mann I. R.
Published: January 2020

Recent observations demonstrating that auroral beads are observed prior to the majority of substorm onsets (Kalmoni et al., 2017, https://doi.org/10.1002/2016GL071826) have reinforced the potential importance of ballooning instabilities for near‐Earth magnetospheric substorm onset. Here we examine pressure anisotropic ballooning instabilities in stretched magnetotail geometries. Our results show that transition from an initially perpendicular anisotropy toward parallel anisotropy reduces the plasma β threshold for triggering a ballooning instability. Such increasingly parallel anisotropies can form as a direct consequence of tail stretching that occurs during the late substorm growth phase through the well‐known effects of drift shell splitting and the competition between betatron and Fermi processes in the tail. We propose such increasingly parallel ballooning triggers auroral substorm onset on field lines in the transition region between dipolar and tail‐like fields, consistent with observational constraints on the location of the onset arc with respect to the ion isotropy boundary in the magnetotail.
The Delayed Island Mass Effect: How Islands can Remotely Trigger Blooms in the Oligotrophic Ocean
Authors: Messié Monique , Petrenko Anne , Doglioli Andrea M. , Aldebert Clément , Martinez Elodie , Koenig Guillaume , Bonnet Sophie , Moutin Thierry
Published: January 2020

In oligotrophic gyres of the tropical ocean, islands can enhance phytoplankton biomass and create hotspots of productivity and biodiversity. This “island mass effect” (IME) is typically identified by increased chlorophyll concentrations next to an island. Here we use a simple plankton model in a Lagrangian framework to represent an unexplained open ocean bloom, demonstrating how islands could have triggered it remotely. This new type of IME, termed “delayed IME,” occurs when nitrate is limiting, N:P ratios are low, and excess phosphate and iron remain in water masses after an initial bloom associated with a “classical” IME. Nitrogen fixers then slowly utilize leftover phosphate and iron while water masses get advected away, resulting in a bloom decoupled in time (several weeks) and space (hundreds of kilometers) from island‐driven nutrient supply. This study suggests that the fertilizing effect of islands on phytoplankton may have been largely underestimated.
Martian Thermospheric Warming Associated With the Planet Encircling Dust Event of 2018
Authors: Jain S. K. , Bougher S. W. , Deighan J. , Schneider N. M. , González Galindo F. , Stewart A. I. F. , Sharrar R. , Kass D. , Murphy J. , Pawlowski D.
Published: January 2020

We report the first observations of Martian thermospheric warming associated with the Planet Encircling Dust Event (PEDE) of 2018. We used dayglow observations made by the Imaging Ultraviolet Spectrograph instrument aboard the MAVEN spacecraft to retrieve the upper atmosphere temperature structures. Our analysis shows that the two‐cell meridional circulation pattern may be operating before the PEDE‐2018, which resulted in the cooling of lower/middle latitudes and warming at higher latitudes. However, after the onset, the existing circulation pattern gets dampened, resulted in a weaker latitudinal temperature structure. We saw that mean temperatures rose by about 20 K for the same local time after the onset of the dust storm. Our 3‐D Mars General Ionosphere Thermosphere Model calculations were able to reproduce the temperatures during the predust and early dust storm but failed to fully capture the temperature trend during the growth phase of the PEDE of 2018.
South Asian Summer Monsoon Response to Aerosol‐Forced Sea Surface Temperatures
Authors: Li Xiaoqiong , Ting Mingfang , You Yujia , Lee Dong‐Eun , Westervelt Daniel M. , Ming Yi
Published: January 2020

Climate models suggest that anthropogenic aerosol‐induced drying dominates the historical rainfall changes over the heavily populated South Asian monsoon region. The regional response depends on both the aerosol fast radiative effect and the slow process through sea surface temperature (SST) cooling. Two atmospheric general circulation models, NCAR‐CAM5 and GFDL‐AM3, are used to investigate the monsoon response to prescribed aerosol‐forced SSTs. The total SST is separated into uniform cooling and a spatially varying component characterized by interhemispheric asymmetry. The monsoon rainfall is predominantly controlled by the nonuniform SSTs, in the local Indian Ocean, South, and East China Seas (IO‐CSs). The reduced meridional SST gradient in the IO‐CSs leads to weakened monsoon circulation, which drives a north‐south dipole rainfall change. The latitudinal location of the dipole shows model dependence due to differences in local SSTs and their meridional gradient, which determines the latitudinal location of the meridional overturning circulation responses.
Collisionless Magnetic Reconnection in an Asymmetric Oxygen Density Configuration
Authors: Kolstø Håkon Midthun , Hesse Michael , Norgren Cecilia , Tenfjord Paul , Spinnangr Susanne Flø , Kwagala Norah
Published: January 2020

Combined with the magnetic field, the distribution of charged particles in the inflow region is expected to control the rate of magnetic reconnection. This paper investigates how the reconnection process is altered by a cold, asymmetrically distributed, oxygen population, which is initially located away from the current layer in the inflow regions. A particle‐in‐cell simulation is used to gain further insight into the dynamics of the system. The time evolution of the reconnection process proceeds rapidly compared to the cyclotron period of O
. Therefore, the oxygen remains, to a good approximation, demagnetized. Thus, Alfvén scaling is not an adequate description of the reconnection rate. A scaling relation for the reconnection rate for an asymmetrically distributed, demagnetized species has been developed. Additionally, we find that an asymmetric density configuration leads to a distinct motion of the reconnection site and generates an asymmetry of the diffusion region and the Hall electric field.
Stability of Marine Organic Matter Respiration Stoichiometry
Authors: Tanioka T. , Matsumoto K.
Published: January 2020

The amount of oxygen consumed during organic matter remineralization critically depends on how much organic carbon is remineralized per unit dissolved oxygen respired (respiratory quotient, RQ) but the global distribution and the mechanisms that control RQ are not well understood. Here we estimate RQ in the surface ocean by using two independent methods, one using satellite‐derived macromolecular composition of phytoplankton and another using objectively gridded nutrient data. Both methods yield mean RQ of ~0.7 with small spatial variability consistent with previous estimates. This pattern is likely to be a result of phytoplankton protein content universally exceeding those of carbohydrates and lipids. At face value, the relative stability of RQ suggests that the remineralization stoichiometry will not affect the ongoing deoxygenation of the world ocean. However, the possibility remains that RQ may increase in the future (e.g., organic matter becoming more carbohydrate‐dominated) and thus ameliorate deoxygenation.
Sensitivity of Blocks and Cyclones in ERA5 to Spatial Resolution and Definition
Authors: Rohrer M. , Martius O. , Raible C. C. , Brönnimann S.
Published: January 2020

ERA5, the fifth‐generation reanalysis of the European Center for Medium‐Range Weather Forecasts, provides long time series of atmospheric fields at high spatial and temporal resolution. It allows detailed studies of atmospheric flow features such as blocks or cyclones. We investigate characteristics of blocks and cyclones in ERA5 using different algorithms, compare the results to ERA5's predecessor, ERA‐interim, and investigate how these characteristics depend on spatial resolution. Generally, ERA5 and ERA‐interim characterize blocks and cyclones similarly. For Lagrangian detection and tracking methods, blocks are more robust than cyclones to changes in resolution and reanalysis choice. Eulerian methods are robust to changes in resolution. Thus, ERA5 provides a state‐of‐the‐art reanalysis for the synoptic‐scale extratropical circulation. We find that Lagrangian cyclone characteristics are strongly dependent on spatial resolution and therefore recommend that model and reanalysis data should be mapped to a common resolution for verification.
Revisiting the Impact of Sea Salt on Climate Sensitivity
Authors: Paulot Fabien , Paynter David , Winton Michael , Ginoux Paul , Zhao Ming , Horowitz Larry W.
Published: January 2020

Recent laboratory and field studies point to an increase of sea salt aerosol (SSA) emissions with temperature, suggesting that SSA may lower climate sensitivity. We assess the impact of a strong (4.2% K
) and weak (0.7% K
) temperature response of SSA emissions on the climate sensitivity of the coupled climate model CM4. We find that the stronger temperature dependence improves the simulation of marine aerosol optical depth sensitivity to temperature and lowers CM4 Transient Climate Response (‐0.12 K) and Equilibrium Climate Sensitivity (‐0.5 K). At
doubling, the higher SSA emission sensitivity causes a negative radiative feedback (‐0.125 
), which can only be partly explained by changes in the radiative effect of SSA (‐0.08 
). Stronger radiative feedbacks are dominated by more negative low‐level cloud feedbacks in the Northern Hemisphere, which are partly offset by more positive feedbacks in the Southern Hemisphere associated with a weaker Atlantic Meridional Overturning Circulation.
Intraplate Volcanism and Regional Geodynamics in NE Asia Revealed by Anisotropic Rayleigh‐Wave Tomography
Authors: Fan Xingli , Chen Qi‐Fu , Legendre C. P. , Guo Zhen
Published: January 2020

Seismic structure related to the magmatic system beneath the potentially hazardous Changbaishan volcano recently becomes hotly debated. In addition, mantle flow dynamics throughout the back‐arc regions in NE Asia remain poorly constrained due to the lack of seismic data in the Korean Peninsula and surrounding ocean regions. In this study we construct a high‐resolution azimuthally anisotropic Rayleigh‐wave phase velocity model in NE Asia, by integrating seismic data from China, North Korea, South Korea, and Japan. The resulting isotropic velocity maps suggest possible existence of a crustal magma chamber beneath the Changbaishan volcano and that the widespread intraplate volcanism in NE Asia likely arises from the upwelling asthenosphere. The obtained anisotropic maps reveal trench‐normal return flow patterns in the back‐arc regions of NE Asia with local variations between East China and northeast China as controlled by the subduction geometry of the Pacific slab.
Direct Evidence of the Pitch Angle Scattering of Relativistic Electrons Induced by EMIC Waves
Authors: Zhu Hui , Chen Lunjin , Claudepierre Seth G. , Zheng Liheng
Published: January 2020

In this study, we analyze an electromagnetic ion cyclotron (EMIC) wave event of rising tone elements recorded by the Van Allen Probes. The pitch angle distributions of relativistic electrons exhibit a direct response to the two elements of EMIC waves: at the intermediate pitch angle, the fluxes are lower; and at the low pitch angle, the fluxes are higher than those when no EMIC was observed. In particular, the observed changes in the pitch angle distributions are most likely to be caused by nonlinear wave‐particle interaction. The calculation of the minimum resonant energy and a test‐particle simulation based on the observed EMIC waves support the role of the nonlinear wave‐particle interaction in the pitch angle scattering. This study provides direct evidence for the nonlinear pitch angle scattering of electrons by EMIC waves.
Does a Damaged‐Fault Zone Mitigate the Near‐Field Impact of Supershear Earthquakes?—Application to the 2018 7.5 Palu, Indonesia, Earthquake
Authors: Oral Elif , Weng Huihui , Ampuero Jean Paul
Published: January 2020

The impact of earthquakes can be severely aggravated by cascading secondary hazards. The 2018
7.5 Palu, Indonesia, earthquake led to devastating tsunamis and landslides, while triggered submarine landslides possibly contributed substantially to generate the tsunami. The rupture was supershear over most of its length, but its speed was unexpectedly slow for a supershear event, between the
wave velocity
and Eshelby's speed
, an unstable speed range in conventional theory. Here, we investigate whether dynamic rupture models including a low‐velocity fault zone can reproduce such a steady supershear rupture with a relatively low speed. We then examine numerically how this peculiar feature of the Palu earthquake could have affected the near‐field ground motion and thus the secondary hazards. Our findings suggest that the presence of a low‐velocity fault zone can explain the unexpected rupture speed and may have mitigated the near‐field ground motion and the induced landslides in Palu.
The Fate of Liquids Trapped During the Earth's Inner Core Growth
Authors: Lasbleis M. , Kervazo M. , Choblet G.
Published: January 2020

The growth history of the inner core is inherently linked to the thermal history of the Earth. The crystallization of the inner core may have been delayed by supercooling and gone through an initial phase of fast growth after the nucleation barrier has been passed, but so far no evidence or constraint has been proposed to time this possible event. With two‐phase flow dynamics, we explore the effect of different growth scenarios for the inner core to determine their effects on its liquid fraction structure. Seismic observations on the melt fraction inside the inner core at present limit the porosity to a maximum of 10% of liquid. Our model provides constraints for the delay in nucleation compared to the time where the first crystal may have started to nucleate, and we find that the supercooling cannot have exceeded 100 K.
The Life Cycle of Annual Waves in the Indian Ocean as Identified by Seamless Diagnosis of the Energy Flux
Authors: Li Zimeng , Aiki Hidenori
Published: January 2020

In previous studies, the role of large‐scale waves in tropical‐extratropical interactions has been little investigated in terms of wave energy transfer owing to the lack of appropriate diagnostic techniques. Using a new seamless scheme, the present study identifies a series of well‐defined horizontal circulation routes of wave energy in the Indian Ocean on an annual basis. One of these features represents a localized cyclonic circulation close to the western boundary in each hemisphere while the other manifests as a basin‐scale cyclonic circulation in the eastern Indian Ocean. For the second baroclinic mode, eastward energy fluxes associated with equatorial Kelvin waves appear when zonal velocity anomaly exhibits eastward and westward peaks (four times per year) in response to the monsoon‐wind cycle. Identification of these key pathways of wave energy circulation enables us to better understand how waves in the tropical and subtropical regions interconnect at the zonal boundaries of the Indian Ocean.
Efficient Image‐Based Simulation of Flow and Transport in Heterogeneous Porous Media: Application of Curvelet Transforms
Authors: Aljasmi Abdullah , Sahimi Muhammad
Published: January 2020

Flow, transport, reaction, adsorption, and deformation (FTRAD) are phenomena that occur in a wide variety of heterogeneous porous media and have been studied for decades. Models of heterogeneous porous formations involve approximations, simplifications, and even unjustified assumptions. With advances in instrumentation, obtaining highly resolved images of such media has become feasible, opening the way to direct image‐based simulation of the FTRAD. Such simulations require, however, intensive computations, limiting their utility. We propose a novel methodology whereby (i) the image is taken to the curvelet space, (ii) all the curvelet coefficients that are smaller than a threshold are set to 0, and (iii) the image is reconstructed. By carrying out image‐based simulations of diffusion and fluid flow in two distinct types of heterogeneous porous media, we demonstrate that simulations in the reconstructed images yield as accurate results as those in the original ones while speeding up the computation by 2 orders of magnitude or better. Thus, the methodology represents a significant step toward the ultimate goal of making direct image‐based simulation of the FTRAD in heterogeneous porous media a standard practice.