The mechanism of lightning that ignites a forest fire and the lightning that occurs above a forest fire are explained at the molecular level. It is based on two phenomena, namely, internal charge separation inside the...The mechanism of lightning that ignites a forest fire and the lightning that occurs above a forest fire are explained at the molecular level. It is based on two phenomena, namely, internal charge separation inside the atmospheric cloud particles and the existence of a layer of positively charged hydrogen atoms sticking out of the surface of the liquid layer of water on the surface of rimers. Strong turbulence-driven collisions of the ice particles and water droplets with the rimers give rise to breakups of the ice particles and water droplets into positively and negatively charged fragments leading to charge separation. Hot weather in a forest contributes to the updraft of hot and humid air, which follows the same physical/chemical processes of normal lightning proposed and explained recently[1]. Lightning would have a high probability of lighting up and burning the dry biological materials in the ground of the forest, leading to a forest (wild) fire. The burning of trees and other plants would release a lot of heat and moisture together with a lot of smoke particles (aerosols) becoming a strong updraft. The condition for creating lightning is again satisfied which would result in further lightning high above the forest wild fire.展开更多
Porous organic molecular materials(POMMs)are an emergent class of molecular-based materials characterized by the formation of extended porous frameworks,mainly held by non-covalent interactions.POMMs represent a varie...Porous organic molecular materials(POMMs)are an emergent class of molecular-based materials characterized by the formation of extended porous frameworks,mainly held by non-covalent interactions.POMMs represent a variety of chemical families,such as hydrogen-bonded organic frameworks,porous organic salts,porous organic cages,C-H···πmicroporous crystals,supramolecular organic frameworks,π-organic frameworks,halogen-bonded organic framework,and intrinsically porous molecular materials.In some porous materials such as zeolites and metal organic frameworks,the integration of multiscale has been adopted to build materials with multifunctionality and optimized properties.Therefore,considering the significant role of hierarchy in porous materials and the growing importance of POMMs in the realm of synthetic porous materials,we consider it appropriate to dedicate for the first time a critical review covering both topics.Herein,we will provide a summary of literature examples showcasing hierarchical POMMs,with a focus on their main synthetic approaches,applications,and the advantages brought forth by introducing hierarchy.展开更多
Cloud electrification is one of the oldest unresolved puzzles in the atmospheric sciences. Though many mechanisms for charge separation in clouds have been proposed, a quantitative understanding of their respective co...Cloud electrification is one of the oldest unresolved puzzles in the atmospheric sciences. Though many mechanisms for charge separation in clouds have been proposed, a quantitative understanding of their respective contribution in a given meteorological situation is lacking. Here we suggest and analyze a hitherto little discussed process. A qualitative picture at the molecular level of the charge separation mechanism of lightning in a thundercloud is proposed. It is based on two key physical/chemical natural phenomena, namely, internal charge separation of the atmospheric impurities/aerosols inside an atmospheric water cluster/droplet/ice particle and the existence of liquid water layers on rimers (graupels and hailstones) forming a layer of dipoles with H<sup>+</sup> pointing out from the air-water interface. Charge separation is achieved through strong collisions among ice particles and water droplets with the rimers in the turbulence of the thundercloud. This work would have significant contribution to cloud electrification and lightning formation.展开更多
Wild edible Termitomyces mushrooms are popular in Southwest China and umami is important flavor qualities of edible mushrooms.This study aimed to understand the umami taste of Termitomyces intermedius and Termitomyces...Wild edible Termitomyces mushrooms are popular in Southwest China and umami is important flavor qualities of edible mushrooms.This study aimed to understand the umami taste of Termitomyces intermedius and Termitomyces aff.bulborhizus.Ten umami peptides from aqueous extracts were separated using a Sephadex G-15 gel filtration chromatography.The intense umami fraction was evaluated by both sensory evaluation and electronic tongue.They were identified as KLNDAQAPK,DSTDEKFLR,VGKGAHLSGEH,MLKKKKLA,SLGFGGPPGY,TVATFSSSTKPDD,AMDDDEADLLLLAM,VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK.Seven peptides,except VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK were selectively synthesized to verify their taste characteristics.All these 10 peptides had umami or salt taste.The 10 peptides were conducted by molecular docking to study their interaction with identified peptides and the umami taste receptor T1R1/T1R3.All these 10 peptides perfectly docked the active residues in the T1R3 subunit.Our results provide theoretical basis for the umami taste and address the umami mechanism of two wild edible Termitomyces mushrooms.展开更多
Background: Improving Water, Sanitation and Hygiene in health care settings is a critical prerequisite for achieving national health goals and Sustainable Development Goals (SDGs). The World Health Organization (WHO) ...Background: Improving Water, Sanitation and Hygiene in health care settings is a critical prerequisite for achieving national health goals and Sustainable Development Goals (SDGs). The World Health Organization (WHO) has set a target for each United Nations member state to reach by 2030. Each member state is required to reach by 2022, 2025 and 2030 at least 60%, 80% and 100%, respectively of basic level of service of the five elements which are water, sanitation, hygiene, waste management and environmental cleaning. Methods: This study aimed to evaluate and document the current state of basic water, sanitation, and hygiene services in all lower-level health care facilities in the Dar es Salaam region of Tanzania as of July 2022. A cross-sectional study was conducted in 99 public dispensaries in the Dar es Salaam region’s five councils: Ubungo, Kigamboni, Kinondoni and Temeke Municipalities, and Ilala City. The interviewee form and observational checklists were both digitalized using the Kobo tool software. The respondents were health care facility in-charges or nurse in-charges. Data were downloaded, validated, and imported to Stata version 15 for analysis. Results: The basic WASH level per JMP is far below the target in 2022. Each member state by 2022 is required to reach at least 60% of the basic level of service of each element. We found a low coverage of basic WASH in the 99 dispensaries included in this study. The basic WASH coverage was met in only 10 (10.1%) of the dispensaries, while the remaining 89 (89.9%) dispensaries fall on limited WASH services. Conclusion: This study revealed lower coverage of basic WASH services in dispensaries. An urgent need is required to improve the status of WASH in all the dispensaries and facilitate the provision of quality health care services, patient safety and reduce health care associated infections.展开更多
Bovine tuberculosis (bTB) is an endemic zoonosis significantly affects animal health in Burkina Faso. The primary causative agent is Mycobacterium tuberculosis (M. tuberculosis) complex, mainly M. bovis. Cattle are co...Bovine tuberculosis (bTB) is an endemic zoonosis significantly affects animal health in Burkina Faso. The primary causative agent is Mycobacterium tuberculosis (M. tuberculosis) complex, mainly M. bovis. Cattle are considered as natural reservoir of M. bovis. However, in Burkina Faso, the circulation of these strains remains poorly understood and documented. This study aimed to identify and characterize Mycobacterium strains from suspected carcasses during routine meat inspection at Bobo-Dioulasso refrigerated slaughterhouse. A prospective cross-sectional study was conducted from January 2021 to December 2022 on cases of seizures linked to suspected bovine tuberculosis. Microbiological and molecular analyzes were used for mycobacterial strain isolation and characterization. Out of 50 samples, 24% tested positive by microscopy and 12% by culture. Molecular analysis identified 6 strains of Mycobacteria, exclusively Mycobacterium bovis specifically the subspecies bovis (Mycobacterium bovis subsp bovis). In conclusion, M. bovis subsp bovis is the primary agent responsible for bovine tuberculosis in Bobo-Dioulasso. Continuous monitoring of mycobacterial strains is therefore necessary for the effective control of this pathology in the local cattle population.展开更多
Endometriosis is a common chronic gynecological disease with endometrial cell implantation outside the uterus.Angiogenesis is a major pathophysiology in endometriosis.Our previous studies have demonstrated that the pr...Endometriosis is a common chronic gynecological disease with endometrial cell implantation outside the uterus.Angiogenesis is a major pathophysiology in endometriosis.Our previous studies have demonstrated that the prodrug of epigallocatechin gallate(ProEGCG)exhibits superior anti-endometriotic and anti-angiogenic effects compared to epigallocatechin gallate(EGCG).However,their direct binding targets and underlying mechanisms for the differential effects remain unknown.In this study,we demonstrated that oral ProEGCG can be effective in preventing and treating endometriosis.Additionally,1D and 2D Proteome Integral Solubility Alteration assay-based chemical proteomics identified metadherin(MTDH)and PX domain containing serine/threonine kinase-like(PXK)as novel binding targets of EGCG and ProEGCG,respectively.Computational simulation and BioLayer interferometry were used to confirm their binding affinity.Our results showed that MTDH-EGCG inhibited protein kinase B(Akt)-mediated angiogenesis,while PXK-ProEGCG inhibited epidermal growth factor(EGF)-mediated angiogenesis via the EGF/hypoxia-inducible factor(HIF-1a)/vascular endothelial growth factor(VEGF)pathway.In vitro and in vivo knockdown assays and microvascular network imaging further confirmed the involvement of these signaling pathways.Moreover,our study demonstrated that ProEGCG has superior therapeutic effects than EGCG by targeting distinct signal transduction pathways and may act as a novel antiangiogenic therapy for endometriosis.展开更多
Recently,nano-systems based on molecular communications via diffusion(MCvD)have been implemented in a variety of nanomedical applications,most notably in targeted drug delivery system(TDDS)scenarios.Furthermore,becaus...Recently,nano-systems based on molecular communications via diffusion(MCvD)have been implemented in a variety of nanomedical applications,most notably in targeted drug delivery system(TDDS)scenarios.Furthermore,because the MCvD is unreliable and there exists molecular noise and inter symbol interference(ISI),cooperative nano-relays can acquire the reliability for drug delivery to targeted diseased cells,especially if the separation distance between the nano transmitter and nano receiver is increased.In this work,we propose an approach for optimizing the performance of the nano system using cooperative molecular communications with a nano relay scheme,while accounting for blood flow effects in terms of drift velocity.The fractions of the molecular drug that should be allocated to the nano transmitter and nano relay positioning are computed using a collaborative optimization problem solved by theModified Central Force Optimization(MCFO)algorithm.Unlike the previous work,the probability of bit error is expressed in a closed-form expression.It is used as an objective function to determine the optimal velocity of the drug molecules and the detection threshold at the nano receiver.The simulation results show that the probability of bit error can be dramatically reduced by optimizing the drift velocity,detection threshold,location of the nano-relay in the proposed nano system,and molecular drug budget.展开更多
The solubility of H_(2)S was measured in solutions of N-butyl-N-methylmorpholine acetate([Bmmorp][Ac])containing 20%-40%(mass)water at experimental temperatures ranged from 298.15 to 328.15 K and pressures up to 320 k...The solubility of H_(2)S was measured in solutions of N-butyl-N-methylmorpholine acetate([Bmmorp][Ac])containing 20%-40%(mass)water at experimental temperatures ranged from 298.15 to 328.15 K and pressures up to 320 k Pa.The total solubility of H_(2)S increased with higher temperatures,lower pressures,and reduced water content.The reaction equilibrium thermodynamic model was used to correlate the solubility data.The results indicate that the chemical reaction equilibrium constant decrease with increasing water content and temperature,whereas Henry constant increase with increasing water content and temperature.Compared with other ionic liquids,H_(2)S exhibits a higher physical absorption enthalpy and a lower chemical absorption enthalpy in[Bmmorp][Ac]aqueous solution.This suggests that[Bmmorp][Ac]has a strong physical affinity for H_(2)S and low energy requirement for desorption.Quantum chemical methods were used to investigate the molecular mechanism of H_(2)S absorption in ionic liquids.The interaction energy analysis revealed that the binding of H_(2)S with the ionic liquid in a1:2 ratio is more stable.Detailed analyses by the methods of the interaction region indicator and the atoms in molecules were conducted to the interactions between H_(2)S and the ionic liquid.展开更多
A new species of the genus Brachytarsophrys,named Brachytarsophrys wenshanensis sp.nov.,has been identified in southeastern Yunnan,China.This new species can be readily distinguished from other known congeners by both...A new species of the genus Brachytarsophrys,named Brachytarsophrys wenshanensis sp.nov.,has been identified in southeastern Yunnan,China.This new species can be readily distinguished from other known congeners by both morphological criterion and molecular analysis of three mitochondrial gene segments:16S,COI,and Cytb.This classification is based on the following morphological characters:(1)medium body size(SVL 83.8–85.1 mm in two adult males);(2)enormous head,with head width nearly 1.2 times the length;(3)tongue pyriform,feebly notched;(4)non-meeting heels;(5)male lacking nuptial pad;(6)tibiotarsal articulation reaching angle of mouth when hindlimbs are extended forward alongside the body;(7)absence of outer metatarsal tubercle,inner metatarsal tubercle elliptic and approximately equal to first toe;(8)rudimentary toe webbing,webbing formula:Ⅰ(2–)–(2^(++))Ⅱ(2^(–))–(3^(++))Ⅲ(2^(½))–(4)Ⅳ(4^(+))–(2^(⅔))V;(9)lateral fringes narrow;(10)dermal ridge or glandular fold on dorsum absent;(11)pectoral glands distinct and irregular,femoral gland small.Our work increases the number of species within the genus Brachytarsophrys to 9.展开更多
Shear-thinning fluids have been widely used in microfluidic systems,but their internal flow mechanism is still unclear.Therefore,in this paper,molecular dynamics simulations are used to study the laminar flow of shear...Shear-thinning fluids have been widely used in microfluidic systems,but their internal flow mechanism is still unclear.Therefore,in this paper,molecular dynamics simulations are used to study the laminar flow of shear-thinning fluid in a microchannel.We validated the feasibility of our simulation method by evaluating the mean square displacement and Reynolds number of the solution layers.The results show that the change rule of the fluid system's velocity profile and interaction energy can reflect the shear-thinning characteristics of the fluids.The velocity profile resembles a top-hat shape,intensifying as the fluid's power law index decreases.The interaction energy between the wall and the fluid decreases gradually with increasing velocity,and a high concentration of non-Newtonian fluid reaches a plateau sooner.Moreover,the velocity profile of the fluid is related to the molecule number density distribution and their values are inversely proportional.By analyzing the radial distribution function,we found that the hydrogen bonds between solute and water molecules weaken with the increase in velocity.This observation offers an explanation for the shear-thinning phenomenon of the non-Newtonian flow from a micro perspective.展开更多
By replacing hexyl chains in poly(3-hexylthiophene)(P3HT)with 2-propoxyethyls,four poly(3-(2-propoxyethyl)thiophene)(P3POET)homopolymers with comparable polydispersity indexes(PDI)and regioregularities were prepared h...By replacing hexyl chains in poly(3-hexylthiophene)(P3HT)with 2-propoxyethyls,four poly(3-(2-propoxyethyl)thiophene)(P3POET)homopolymers with comparable polydispersity indexes(PDI)and regioregularities were prepared herein in addition with step increment of about 7 kDa on numberaverage molecular weight(M_(n))from around 11 to 32 kDa(accordingly denoted as P11k,P18k,P25k,and P32k).When doped in film by FeCl_(3)at the optimized conditions,the maximum power factor(PF_(max))increases greatly from 4.3μW·m^(-1)·K^(-2)for P11k to 8.8μW·m^(-1)·K^(-2)for P18k,and further to 9.7μW·m^(-1)·K^(-2)for P25k,followed by a slight decrease to 9.2μW·m^(-1)·K^(-2)for P32k.The close Seebeck coefficients(S)at PF_(max)are observed in these doped polymer films due to their consistent frontier orbital energy levels and Fermi levels.The main contribution to this PF_(max)evolution thus comes from the corresponding conductivities(σ).Theσvariation of the doped films can be rationally correlated with their microstructure evolution.展开更多
While the interaction between information and disease in static networks has been extensively investigated,many studies have ignored the characteristics of network evolution.In this study,we construct a new two-layer ...While the interaction between information and disease in static networks has been extensively investigated,many studies have ignored the characteristics of network evolution.In this study,we construct a new two-layer coupling model to explore the interactions between information and disease.The upper layer describes the diffusion of disease-related information,and the lower layer represents the disease transmission.We then use power-law distributions to examine the influence of asymmetric activity levels on dynamic propagation,revealing a mapping relationship characterizing the interconnected propagation of information and diseases among partial nodes within the network.Subsequently,we derive the disease outbreak threshold by using the microscopic Markov-chain approach(MMCA).Finally,we perform extensive Monte Carlo(MC)numerical simulations to verify the accuracy of our theoretical results.Our findings indicate that the activity levels of individuals in the disease transmission layer have a more significant influence on disease transmission compared with the individual activity levels in the information diffusion layer.Moreover,reducing the damping factor can delay disease outbreaks and suppress disease transmission,while improving individual quarantine measures can contribute positively to disease control.This study provides valuable insights into policymakers for developing outbreak prevention and control strategies.展开更多
In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as an...In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as ancillary results,estimates of the absolute changes in sea level at the same locations.To verify our processing approach to determining vertical motion,we first modeled vertical motion at the International GNSS Service(IGS)THTI station located in the capital island of Tahiti and compared our estimate with previous independent determinations,with a good agreement.We obtained the following estimates for the vertical land motions at the tide gauges:Tubuai island,Austral Archipelago-0.92±0.17 mm/yr,Vairao village,Tahiti Iti:-0.49±0.39 mm/yr,Rikitea,Gambier Archipelago-0.43±0.17 mm/yr.The absolute variations of the sea level are:Tubuai island,Austral Archipelago 5.25±0.60 mm/yr,Vairao village,Tahiti Iti:3.62±0.52 mm/yr,Rikitea,Gambier Archipelago 1.52±0.23 mm/yr.We discuss these absolute values in light of the values obtained from altimetric measurements and other means in French Polynesia.展开更多
Resistance to pentavalent antimonial drugs and the lack of vaccines make it urgent to find novel therapeutic options to treat Leishmaniasis, a tropical disease caused by the Leishmania protozoan parasite. The study re...Resistance to pentavalent antimonial drugs and the lack of vaccines make it urgent to find novel therapeutic options to treat Leishmaniasis, a tropical disease caused by the Leishmania protozoan parasite. The study reported here is to investigate if Streptomycin, an aminoglycoside, and Amphotericin B, the second-line treatment drug, exhibit antileishmanial activity through a similar mechanism. By using MOE (Molecular Operating Environment), we performed molecular docking studies on these drugs binding to a range of targets including ribosome targets in Leishmania and H. sapiens. Our study shows that the two drugs do not bind to the same pockets in Leishmania targets but to the same pockets in the human ribosome, with some differences in interactions. Moreover, our 2D maps indicated that Amphotericin B binds to the A-site in the human cytoplasmic ribosome, whereas streptomycin does not.展开更多
Objective: There is an ongoing debate about whether the management of gastroenteropancreatic(GEP)neuroendocrine carcinoma(NEC) should follow the guidelines of small-cell lung cancer(SCLC). We aim to identify the genet...Objective: There is an ongoing debate about whether the management of gastroenteropancreatic(GEP)neuroendocrine carcinoma(NEC) should follow the guidelines of small-cell lung cancer(SCLC). We aim to identify the genetic differences of GEPNEC and its counterpart.Methods: We recruited GEPNEC patients as the main cohort, with lung NEC and digestive adenocarcinomas as comparative cohorts. All patients undergone next-generation sequencing(NGS). Different gene alterations were compared and analyzed between GEPNEC and lung NEC(LNEC), GEPNEC and adenocarcinoma to yield the remarkable genes.Results: We recruited 257 patients, including 99 GEPNEC, 57 LNEC, and 101 digestive adenocarcinomas.Among the mutations, KRAS, RB1, TERT, IL7R, and CTNNB1 were found to have different gene alterations between GEPNEC and LNEC samples. Specific genes for each site were revealed: gastric NEC(TERT amplification),colorectal NEC(KRAS mutation), and bile tract NEC(ARID1A mutation). The gene disparities between small-cell NEC(SCNEC) and large-cell NEC(LCNEC) were KEAP1 and CDH1. Digestive adenocarcinoma was also compared with GEPNEC and suggested RB1, APC, and KRAS as significant genes. The TP53/RB1 mutation pattern was associated with first-line effectiveness. Putative targetable genes and biomarkers in GEPNEC were identified in22.2% of the patients, and they had longer progression-free survival(PFS) upon targetable treatment [12.5 months vs. 3.0 months, HR=0.40(0.21-0.75), P=0.006].Conclusions: This work demonstrated striking gene distinctions in GEPNEC compared with LNEC and adenocarcinoma and their clinical utility.展开更多
Determining the adsorption of shale gas on complex surfaces remains a challenge in molecular simulation studies.Difficulties essentially stem from the need to create a realistic shale structure model in terms of miner...Determining the adsorption of shale gas on complex surfaces remains a challenge in molecular simulation studies.Difficulties essentially stem from the need to create a realistic shale structure model in terms of mineral heterogeneityand multiplicity.Moreover,precise characterization of the competitive adsorption of hydrogen andmethane in shale generally requires the experimental determination of the related adsorptive capacity.In thisstudy,the adsorption of adsorbates,methane(CH_(4)),and hydrogen(H_(2))on heterogeneous shale surface modelsof Kaolinite,Orthoclase,Muscovite,Mica,C_(60),and Butane has been simulated in the frame of a moleculardynamic’s numerical technique.The results show that these behaviors are influenced by pressure and potentialenergy.On increasing the pressure from 500 to 2000 psi,the sorption effect for CH_(4)significantly increasesbut shows a decline at a certain stage(if compared to H_(2)).The research findings also indicate that raw shalehas a higher capacity to adsorb CH_(4)compared to hydrogen.However,in shale,this difference is negligible.展开更多
In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular...In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular dynamics simulation.In liquid Mg-rich Mg-Y alloys,the strong Mg-Y interaction is determined,which promotes the formation of fivefold symmetric local structure.For Mg-Zn alloys,the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure.Due to the coexistence of Y and Zn,the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy,and contributes to the clustering of Mg,Y,Zn launched from Zn.What is more,the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys.These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure,which provides a new insight into the formation mechanism of LPSO structure at atomic level.展开更多
At present,one of the methods used to determine the height of points on the Earth’s surface is Global Navigation Satellite System(GNSS)leveling.It is possible to determine the orthometric or normal height by this met...At present,one of the methods used to determine the height of points on the Earth’s surface is Global Navigation Satellite System(GNSS)leveling.It is possible to determine the orthometric or normal height by this method only if there is a geoid or quasi-geoid height model available.This paper proposes the methodology for local correction of the heights of high-order global geoid models such as EGM08,EIGEN-6C4,GECO,and XGM2019e_2159.This methodology was tested in different areas of the research field,covering various relief forms.The dependence of the change in corrected height accuracy on the input data was analyzed,and the correction was also conducted for model heights in three tidal systems:"tide free","mean tide",and"zero tide".The results show that the heights of EIGEN-6C4 model can be corrected with an accuracy of up to 1 cm for flat and foothill terrains with the dimensionality of 1°×1°,2°×2°,and 3°×3°.The EGM08 model presents an almost identical result.The EIGEN-6C4 model is best suited for mountainous relief and provides an accuracy of 1.5 cm on the 1°×1°area.The height correction accuracy of GECO and XGM2019e_2159 models is slightly poor,which has fuzziness in terms of numerical fluctuation.展开更多
Temperature effect on atomic deformation of nanotwinned Ni (nt-Ni) under localized nanoindentation is investigated in comparison with nanocrystalline Ni (nc-Ni) through molecular simulation.The nt-Ni exhibits enhanced...Temperature effect on atomic deformation of nanotwinned Ni (nt-Ni) under localized nanoindentation is investigated in comparison with nanocrystalline Ni (nc-Ni) through molecular simulation.The nt-Ni exhibits enhanced critical load and hardness compared to nc-Ni,where perfect,stair-rod and Shockley dislocations are activated at (111),(111) and (111) slip planes in nt-Ni compared to only SSockley dislocation nucleation at (111) and (111) slip planes of nc-Ni.The nt-Ni exhibits a less significant indentation size effect in comparison with nc-Ni due to the dislocation slips hindrance of the twin boundary.The atomic deformation associated with the indentation size effect is investigated during dislocation transmission.Different from the decreasing partial slips parallel to the indenter surface in nc-Ni with increasing temperature,the temperaturedependent atomic deformation of nt-Ni is closely related to the twin boundary:from the partial slips parallel to the twin boundary (~10 K),to increased confined layer slips and decreased twin migration(300 K–600 K),to decreased confined layer slips and increased dislocation interaction of dislocation pinning and dissociation (900 K–1200 K).Dislocation density and atomic structure types through quantitative analysis are implemented to further reveal the above-mentioned dislocation motion and atomic structure alteration.Our study is helpful for understanding the temperature-dependent plasticity of twin boundary in nanotwinned materials.展开更多
文摘The mechanism of lightning that ignites a forest fire and the lightning that occurs above a forest fire are explained at the molecular level. It is based on two phenomena, namely, internal charge separation inside the atmospheric cloud particles and the existence of a layer of positively charged hydrogen atoms sticking out of the surface of the liquid layer of water on the surface of rimers. Strong turbulence-driven collisions of the ice particles and water droplets with the rimers give rise to breakups of the ice particles and water droplets into positively and negatively charged fragments leading to charge separation. Hot weather in a forest contributes to the updraft of hot and humid air, which follows the same physical/chemical processes of normal lightning proposed and explained recently[1]. Lightning would have a high probability of lighting up and burning the dry biological materials in the ground of the forest, leading to a forest (wild) fire. The burning of trees and other plants would release a lot of heat and moisture together with a lot of smoke particles (aerosols) becoming a strong updraft. The condition for creating lightning is again satisfied which would result in further lightning high above the forest wild fire.
基金the MICINN (Spain)(Projects PID2019-104778GB-I00, PID2020-115100GB-I00Excellence Unit “Maria de Maeztu” CEX2019-000919-M)+5 种基金the Royal Society of Chemistryfunded by Generalitat Valenciana(PROMETEU/2021/054 and SEJI/2020/034)the “Ramón y Cajal” program (RYC2019-027940-I)the Royal Society (RGSR1221390)Royal Society of Chemistry (R21-5119312833) for the funding.
文摘Porous organic molecular materials(POMMs)are an emergent class of molecular-based materials characterized by the formation of extended porous frameworks,mainly held by non-covalent interactions.POMMs represent a variety of chemical families,such as hydrogen-bonded organic frameworks,porous organic salts,porous organic cages,C-H···πmicroporous crystals,supramolecular organic frameworks,π-organic frameworks,halogen-bonded organic framework,and intrinsically porous molecular materials.In some porous materials such as zeolites and metal organic frameworks,the integration of multiscale has been adopted to build materials with multifunctionality and optimized properties.Therefore,considering the significant role of hierarchy in porous materials and the growing importance of POMMs in the realm of synthetic porous materials,we consider it appropriate to dedicate for the first time a critical review covering both topics.Herein,we will provide a summary of literature examples showcasing hierarchical POMMs,with a focus on their main synthetic approaches,applications,and the advantages brought forth by introducing hierarchy.
文摘Cloud electrification is one of the oldest unresolved puzzles in the atmospheric sciences. Though many mechanisms for charge separation in clouds have been proposed, a quantitative understanding of their respective contribution in a given meteorological situation is lacking. Here we suggest and analyze a hitherto little discussed process. A qualitative picture at the molecular level of the charge separation mechanism of lightning in a thundercloud is proposed. It is based on two key physical/chemical natural phenomena, namely, internal charge separation of the atmospheric impurities/aerosols inside an atmospheric water cluster/droplet/ice particle and the existence of liquid water layers on rimers (graupels and hailstones) forming a layer of dipoles with H<sup>+</sup> pointing out from the air-water interface. Charge separation is achieved through strong collisions among ice particles and water droplets with the rimers in the turbulence of the thundercloud. This work would have significant contribution to cloud electrification and lightning formation.
基金supported by the Yunnan Key Project of Science and Technology(202202AE090001)Postdoctoral Directional Training Foundation of Yunnan Province(E23174K2)Postdoctoral Research Funding Projects of Yunnan Province,China(E2313442)。
文摘Wild edible Termitomyces mushrooms are popular in Southwest China and umami is important flavor qualities of edible mushrooms.This study aimed to understand the umami taste of Termitomyces intermedius and Termitomyces aff.bulborhizus.Ten umami peptides from aqueous extracts were separated using a Sephadex G-15 gel filtration chromatography.The intense umami fraction was evaluated by both sensory evaluation and electronic tongue.They were identified as KLNDAQAPK,DSTDEKFLR,VGKGAHLSGEH,MLKKKKLA,SLGFGGPPGY,TVATFSSSTKPDD,AMDDDEADLLLLAM,VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK.Seven peptides,except VEDEDEKPKEK,SPEEKKEEET and PEGADKPNK were selectively synthesized to verify their taste characteristics.All these 10 peptides had umami or salt taste.The 10 peptides were conducted by molecular docking to study their interaction with identified peptides and the umami taste receptor T1R1/T1R3.All these 10 peptides perfectly docked the active residues in the T1R3 subunit.Our results provide theoretical basis for the umami taste and address the umami mechanism of two wild edible Termitomyces mushrooms.
文摘Background: Improving Water, Sanitation and Hygiene in health care settings is a critical prerequisite for achieving national health goals and Sustainable Development Goals (SDGs). The World Health Organization (WHO) has set a target for each United Nations member state to reach by 2030. Each member state is required to reach by 2022, 2025 and 2030 at least 60%, 80% and 100%, respectively of basic level of service of the five elements which are water, sanitation, hygiene, waste management and environmental cleaning. Methods: This study aimed to evaluate and document the current state of basic water, sanitation, and hygiene services in all lower-level health care facilities in the Dar es Salaam region of Tanzania as of July 2022. A cross-sectional study was conducted in 99 public dispensaries in the Dar es Salaam region’s five councils: Ubungo, Kigamboni, Kinondoni and Temeke Municipalities, and Ilala City. The interviewee form and observational checklists were both digitalized using the Kobo tool software. The respondents were health care facility in-charges or nurse in-charges. Data were downloaded, validated, and imported to Stata version 15 for analysis. Results: The basic WASH level per JMP is far below the target in 2022. Each member state by 2022 is required to reach at least 60% of the basic level of service of each element. We found a low coverage of basic WASH in the 99 dispensaries included in this study. The basic WASH coverage was met in only 10 (10.1%) of the dispensaries, while the remaining 89 (89.9%) dispensaries fall on limited WASH services. Conclusion: This study revealed lower coverage of basic WASH services in dispensaries. An urgent need is required to improve the status of WASH in all the dispensaries and facilitate the provision of quality health care services, patient safety and reduce health care associated infections.
文摘Bovine tuberculosis (bTB) is an endemic zoonosis significantly affects animal health in Burkina Faso. The primary causative agent is Mycobacterium tuberculosis (M. tuberculosis) complex, mainly M. bovis. Cattle are considered as natural reservoir of M. bovis. However, in Burkina Faso, the circulation of these strains remains poorly understood and documented. This study aimed to identify and characterize Mycobacterium strains from suspected carcasses during routine meat inspection at Bobo-Dioulasso refrigerated slaughterhouse. A prospective cross-sectional study was conducted from January 2021 to December 2022 on cases of seizures linked to suspected bovine tuberculosis. Microbiological and molecular analyzes were used for mycobacterial strain isolation and characterization. Out of 50 samples, 24% tested positive by microscopy and 12% by culture. Molecular analysis identified 6 strains of Mycobacteria, exclusively Mycobacterium bovis specifically the subspecies bovis (Mycobacterium bovis subsp bovis). In conclusion, M. bovis subsp bovis is the primary agent responsible for bovine tuberculosis in Bobo-Dioulasso. Continuous monitoring of mycobacterial strains is therefore necessary for the effective control of this pathology in the local cattle population.
基金supported by the GRF RGC&CRF,Hong Kong(Grant Nos.:475012 and C5045-20 EF)HMRF,Hong Kong(Grant No.:03141386)+3 种基金ITF,Hong Kong(Grant No.:ITS/209/12)UGC Direct Grant 2011,2012,2021.032HKOG Trust Fund 2011,2014,2019the National Natural Science Foundation of China(Grant Nos.:81974225 and 82201823)。
文摘Endometriosis is a common chronic gynecological disease with endometrial cell implantation outside the uterus.Angiogenesis is a major pathophysiology in endometriosis.Our previous studies have demonstrated that the prodrug of epigallocatechin gallate(ProEGCG)exhibits superior anti-endometriotic and anti-angiogenic effects compared to epigallocatechin gallate(EGCG).However,their direct binding targets and underlying mechanisms for the differential effects remain unknown.In this study,we demonstrated that oral ProEGCG can be effective in preventing and treating endometriosis.Additionally,1D and 2D Proteome Integral Solubility Alteration assay-based chemical proteomics identified metadherin(MTDH)and PX domain containing serine/threonine kinase-like(PXK)as novel binding targets of EGCG and ProEGCG,respectively.Computational simulation and BioLayer interferometry were used to confirm their binding affinity.Our results showed that MTDH-EGCG inhibited protein kinase B(Akt)-mediated angiogenesis,while PXK-ProEGCG inhibited epidermal growth factor(EGF)-mediated angiogenesis via the EGF/hypoxia-inducible factor(HIF-1a)/vascular endothelial growth factor(VEGF)pathway.In vitro and in vivo knockdown assays and microvascular network imaging further confirmed the involvement of these signaling pathways.Moreover,our study demonstrated that ProEGCG has superior therapeutic effects than EGCG by targeting distinct signal transduction pathways and may act as a novel antiangiogenic therapy for endometriosis.
基金the Researchers Supporting Project Number(RSP2023R 102)King Saud University,Riyadh,Saudi Arabia.
文摘Recently,nano-systems based on molecular communications via diffusion(MCvD)have been implemented in a variety of nanomedical applications,most notably in targeted drug delivery system(TDDS)scenarios.Furthermore,because the MCvD is unreliable and there exists molecular noise and inter symbol interference(ISI),cooperative nano-relays can acquire the reliability for drug delivery to targeted diseased cells,especially if the separation distance between the nano transmitter and nano receiver is increased.In this work,we propose an approach for optimizing the performance of the nano system using cooperative molecular communications with a nano relay scheme,while accounting for blood flow effects in terms of drift velocity.The fractions of the molecular drug that should be allocated to the nano transmitter and nano relay positioning are computed using a collaborative optimization problem solved by theModified Central Force Optimization(MCFO)algorithm.Unlike the previous work,the probability of bit error is expressed in a closed-form expression.It is used as an objective function to determine the optimal velocity of the drug molecules and the detection threshold at the nano receiver.The simulation results show that the probability of bit error can be dramatically reduced by optimizing the drift velocity,detection threshold,location of the nano-relay in the proposed nano system,and molecular drug budget.
基金Financial support from the National Natural Science Foundation of China(21775081)Shandong Province Natural Science Foundation(ZR2020MB145)。
文摘The solubility of H_(2)S was measured in solutions of N-butyl-N-methylmorpholine acetate([Bmmorp][Ac])containing 20%-40%(mass)water at experimental temperatures ranged from 298.15 to 328.15 K and pressures up to 320 k Pa.The total solubility of H_(2)S increased with higher temperatures,lower pressures,and reduced water content.The reaction equilibrium thermodynamic model was used to correlate the solubility data.The results indicate that the chemical reaction equilibrium constant decrease with increasing water content and temperature,whereas Henry constant increase with increasing water content and temperature.Compared with other ionic liquids,H_(2)S exhibits a higher physical absorption enthalpy and a lower chemical absorption enthalpy in[Bmmorp][Ac]aqueous solution.This suggests that[Bmmorp][Ac]has a strong physical affinity for H_(2)S and low energy requirement for desorption.Quantum chemical methods were used to investigate the molecular mechanism of H_(2)S absorption in ionic liquids.The interaction energy analysis revealed that the binding of H_(2)S with the ionic liquid in a1:2 ratio is more stable.Detailed analyses by the methods of the interaction region indicator and the atoms in molecules were conducted to the interactions between H_(2)S and the ionic liquid.
基金supported by Fundamental Research Fund for Central Universities (SWUKR22014)National Natural Science Foundation of China (NSFC 32170478, 32370478)+2 种基金“Special Fund for Youth Team of Southwest University” (SWU-XJPY202302)Youth Top Talent Program of Chongqing (CQYC 20220510893) to Zhiyong YUANNational Natural Science Foundation of China (NSFC 31900323) to Jinmin CHEN。
文摘A new species of the genus Brachytarsophrys,named Brachytarsophrys wenshanensis sp.nov.,has been identified in southeastern Yunnan,China.This new species can be readily distinguished from other known congeners by both morphological criterion and molecular analysis of three mitochondrial gene segments:16S,COI,and Cytb.This classification is based on the following morphological characters:(1)medium body size(SVL 83.8–85.1 mm in two adult males);(2)enormous head,with head width nearly 1.2 times the length;(3)tongue pyriform,feebly notched;(4)non-meeting heels;(5)male lacking nuptial pad;(6)tibiotarsal articulation reaching angle of mouth when hindlimbs are extended forward alongside the body;(7)absence of outer metatarsal tubercle,inner metatarsal tubercle elliptic and approximately equal to first toe;(8)rudimentary toe webbing,webbing formula:Ⅰ(2–)–(2^(++))Ⅱ(2^(–))–(3^(++))Ⅲ(2^(½))–(4)Ⅳ(4^(+))–(2^(⅔))V;(9)lateral fringes narrow;(10)dermal ridge or glandular fold on dorsum absent;(11)pectoral glands distinct and irregular,femoral gland small.Our work increases the number of species within the genus Brachytarsophrys to 9.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.51775077 and 51909023)。
文摘Shear-thinning fluids have been widely used in microfluidic systems,but their internal flow mechanism is still unclear.Therefore,in this paper,molecular dynamics simulations are used to study the laminar flow of shear-thinning fluid in a microchannel.We validated the feasibility of our simulation method by evaluating the mean square displacement and Reynolds number of the solution layers.The results show that the change rule of the fluid system's velocity profile and interaction energy can reflect the shear-thinning characteristics of the fluids.The velocity profile resembles a top-hat shape,intensifying as the fluid's power law index decreases.The interaction energy between the wall and the fluid decreases gradually with increasing velocity,and a high concentration of non-Newtonian fluid reaches a plateau sooner.Moreover,the velocity profile of the fluid is related to the molecule number density distribution and their values are inversely proportional.By analyzing the radial distribution function,we found that the hydrogen bonds between solute and water molecules weaken with the increase in velocity.This observation offers an explanation for the shear-thinning phenomenon of the non-Newtonian flow from a micro perspective.
基金Funded by the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan Univesity of Technology。
文摘By replacing hexyl chains in poly(3-hexylthiophene)(P3HT)with 2-propoxyethyls,four poly(3-(2-propoxyethyl)thiophene)(P3POET)homopolymers with comparable polydispersity indexes(PDI)and regioregularities were prepared herein in addition with step increment of about 7 kDa on numberaverage molecular weight(M_(n))from around 11 to 32 kDa(accordingly denoted as P11k,P18k,P25k,and P32k).When doped in film by FeCl_(3)at the optimized conditions,the maximum power factor(PF_(max))increases greatly from 4.3μW·m^(-1)·K^(-2)for P11k to 8.8μW·m^(-1)·K^(-2)for P18k,and further to 9.7μW·m^(-1)·K^(-2)for P25k,followed by a slight decrease to 9.2μW·m^(-1)·K^(-2)for P32k.The close Seebeck coefficients(S)at PF_(max)are observed in these doped polymer films due to their consistent frontier orbital energy levels and Fermi levels.The main contribution to this PF_(max)evolution thus comes from the corresponding conductivities(σ).Theσvariation of the doped films can be rationally correlated with their microstructure evolution.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 72174121 and 71774111)the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learningthe Project for the Natural Science Foundation of Shanghai, China (Grant No. 21ZR1444100)
文摘While the interaction between information and disease in static networks has been extensively investigated,many studies have ignored the characteristics of network evolution.In this study,we construct a new two-layer coupling model to explore the interactions between information and disease.The upper layer describes the diffusion of disease-related information,and the lower layer represents the disease transmission.We then use power-law distributions to examine the influence of asymmetric activity levels on dynamic propagation,revealing a mapping relationship characterizing the interconnected propagation of information and diseases among partial nodes within the network.Subsequently,we derive the disease outbreak threshold by using the microscopic Markov-chain approach(MMCA).Finally,we perform extensive Monte Carlo(MC)numerical simulations to verify the accuracy of our theoretical results.Our findings indicate that the activity levels of individuals in the disease transmission layer have a more significant influence on disease transmission compared with the individual activity levels in the information diffusion layer.Moreover,reducing the damping factor can delay disease outbreaks and suppress disease transmission,while improving individual quarantine measures can contribute positively to disease control.This study provides valuable insights into policymakers for developing outbreak prevention and control strategies.
基金the University of French Polynesiafunding by several successive“Decision Aide a la Recherche”(DAR)grants to the Geodesy Observatory of Tahiti from the French Space Agency(CNES)+2 种基金fundings from the local government of French Polynesia(Observatoire Polynesien du Rechauffement Climatique)funding by“National Natural Science Foundation of China”(Grand No.41931075)funding by“the Fundamental Research Funds for the Central Universities"(Grand No.2042022kf1198)。
文摘In this study,we estimate the absolute vertical land motions at three tidal stations with collocated Global Navigation Satellite System(GNSS)receivers over French Polynesia during the period 2007-2020,and obtain,as ancillary results,estimates of the absolute changes in sea level at the same locations.To verify our processing approach to determining vertical motion,we first modeled vertical motion at the International GNSS Service(IGS)THTI station located in the capital island of Tahiti and compared our estimate with previous independent determinations,with a good agreement.We obtained the following estimates for the vertical land motions at the tide gauges:Tubuai island,Austral Archipelago-0.92±0.17 mm/yr,Vairao village,Tahiti Iti:-0.49±0.39 mm/yr,Rikitea,Gambier Archipelago-0.43±0.17 mm/yr.The absolute variations of the sea level are:Tubuai island,Austral Archipelago 5.25±0.60 mm/yr,Vairao village,Tahiti Iti:3.62±0.52 mm/yr,Rikitea,Gambier Archipelago 1.52±0.23 mm/yr.We discuss these absolute values in light of the values obtained from altimetric measurements and other means in French Polynesia.
文摘Resistance to pentavalent antimonial drugs and the lack of vaccines make it urgent to find novel therapeutic options to treat Leishmaniasis, a tropical disease caused by the Leishmania protozoan parasite. The study reported here is to investigate if Streptomycin, an aminoglycoside, and Amphotericin B, the second-line treatment drug, exhibit antileishmanial activity through a similar mechanism. By using MOE (Molecular Operating Environment), we performed molecular docking studies on these drugs binding to a range of targets including ribosome targets in Leishmania and H. sapiens. Our study shows that the two drugs do not bind to the same pockets in Leishmania targets but to the same pockets in the human ribosome, with some differences in interactions. Moreover, our 2D maps indicated that Amphotericin B binds to the A-site in the human cytoplasmic ribosome, whereas streptomycin does not.
基金supported by the Major Program of National Natural Science Foundation of China (No. 91959205)National Natural Science Foundation of China (No. 82141117)+3 种基金The Capital’s Funds for Health Improvement and Research (CFH) (No. 2022-2-1023)Beijing Xisike Clinical Oncology Research Foundation Ypierrefabre (No. 202101-0099)Beijing Municipal Administration of Hospitals Incubating Program (No. PX2020045)Science Foundation of Peking University Cancer Hospital (No. 2020-4)。
文摘Objective: There is an ongoing debate about whether the management of gastroenteropancreatic(GEP)neuroendocrine carcinoma(NEC) should follow the guidelines of small-cell lung cancer(SCLC). We aim to identify the genetic differences of GEPNEC and its counterpart.Methods: We recruited GEPNEC patients as the main cohort, with lung NEC and digestive adenocarcinomas as comparative cohorts. All patients undergone next-generation sequencing(NGS). Different gene alterations were compared and analyzed between GEPNEC and lung NEC(LNEC), GEPNEC and adenocarcinoma to yield the remarkable genes.Results: We recruited 257 patients, including 99 GEPNEC, 57 LNEC, and 101 digestive adenocarcinomas.Among the mutations, KRAS, RB1, TERT, IL7R, and CTNNB1 were found to have different gene alterations between GEPNEC and LNEC samples. Specific genes for each site were revealed: gastric NEC(TERT amplification),colorectal NEC(KRAS mutation), and bile tract NEC(ARID1A mutation). The gene disparities between small-cell NEC(SCNEC) and large-cell NEC(LCNEC) were KEAP1 and CDH1. Digestive adenocarcinoma was also compared with GEPNEC and suggested RB1, APC, and KRAS as significant genes. The TP53/RB1 mutation pattern was associated with first-line effectiveness. Putative targetable genes and biomarkers in GEPNEC were identified in22.2% of the patients, and they had longer progression-free survival(PFS) upon targetable treatment [12.5 months vs. 3.0 months, HR=0.40(0.21-0.75), P=0.006].Conclusions: This work demonstrated striking gene distinctions in GEPNEC compared with LNEC and adenocarcinoma and their clinical utility.
基金PETRONAS Research fund(PRF)under PETRONAS Teknologi Transfer(PTT)Pre-Commercialization—External:YUTP-PRG Cycle 2022(015PBC-020).
文摘Determining the adsorption of shale gas on complex surfaces remains a challenge in molecular simulation studies.Difficulties essentially stem from the need to create a realistic shale structure model in terms of mineral heterogeneityand multiplicity.Moreover,precise characterization of the competitive adsorption of hydrogen andmethane in shale generally requires the experimental determination of the related adsorptive capacity.In thisstudy,the adsorption of adsorbates,methane(CH_(4)),and hydrogen(H_(2))on heterogeneous shale surface modelsof Kaolinite,Orthoclase,Muscovite,Mica,C_(60),and Butane has been simulated in the frame of a moleculardynamic’s numerical technique.The results show that these behaviors are influenced by pressure and potentialenergy.On increasing the pressure from 500 to 2000 psi,the sorption effect for CH_(4)significantly increasesbut shows a decline at a certain stage(if compared to H_(2)).The research findings also indicate that raw shalehas a higher capacity to adsorb CH_(4)compared to hydrogen.However,in shale,this difference is negligible.
基金supported by National Natural Science Foundation of China,China(No.51901117,51801116)Youth Innovation and Technology Support Program of Shandong Provincial Colleges and Universities,China(No.2020KJA002)+2 种基金Youth Fund of Shandong Academy of Sciences,China(2020QN0021)Innovation Pilot Project for Fusion of Science,Education and Industry(International Cooperation)from Qilu University of Technology(Shandong Academy of Sciences),China(No.2020KJC-GH03)Several Policies on Promoting Collaborative Innovation and Industrialization of Achievements in Universities and Research Institutes,China(No.2019GXRC030)。
文摘In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular dynamics simulation.In liquid Mg-rich Mg-Y alloys,the strong Mg-Y interaction is determined,which promotes the formation of fivefold symmetric local structure.For Mg-Zn alloys,the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure.Due to the coexistence of Y and Zn,the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy,and contributes to the clustering of Mg,Y,Zn launched from Zn.What is more,the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys.These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure,which provides a new insight into the formation mechanism of LPSO structure at atomic level.
基金the International Center for Global Earth Models(ICGEM)for the height anomaly and gravity anomaly data and Bureau Gravimetrique International(BGI)for free-air gravity anomaly data from the World Gravity Map project(WGM2012)The authors are grateful to Głowny Urza˛d Geodezji i Kartografii of Poland for the height anomaly data of the quasi-geoid PL-geoid2021.
文摘At present,one of the methods used to determine the height of points on the Earth’s surface is Global Navigation Satellite System(GNSS)leveling.It is possible to determine the orthometric or normal height by this method only if there is a geoid or quasi-geoid height model available.This paper proposes the methodology for local correction of the heights of high-order global geoid models such as EGM08,EIGEN-6C4,GECO,and XGM2019e_2159.This methodology was tested in different areas of the research field,covering various relief forms.The dependence of the change in corrected height accuracy on the input data was analyzed,and the correction was also conducted for model heights in three tidal systems:"tide free","mean tide",and"zero tide".The results show that the heights of EIGEN-6C4 model can be corrected with an accuracy of up to 1 cm for flat and foothill terrains with the dimensionality of 1°×1°,2°×2°,and 3°×3°.The EGM08 model presents an almost identical result.The EIGEN-6C4 model is best suited for mountainous relief and provides an accuracy of 1.5 cm on the 1°×1°area.The height correction accuracy of GECO and XGM2019e_2159 models is slightly poor,which has fuzziness in terms of numerical fluctuation.
基金supported by the National Natural Science Foundation of China (Grant No.11572090)。
文摘Temperature effect on atomic deformation of nanotwinned Ni (nt-Ni) under localized nanoindentation is investigated in comparison with nanocrystalline Ni (nc-Ni) through molecular simulation.The nt-Ni exhibits enhanced critical load and hardness compared to nc-Ni,where perfect,stair-rod and Shockley dislocations are activated at (111),(111) and (111) slip planes in nt-Ni compared to only SSockley dislocation nucleation at (111) and (111) slip planes of nc-Ni.The nt-Ni exhibits a less significant indentation size effect in comparison with nc-Ni due to the dislocation slips hindrance of the twin boundary.The atomic deformation associated with the indentation size effect is investigated during dislocation transmission.Different from the decreasing partial slips parallel to the indenter surface in nc-Ni with increasing temperature,the temperaturedependent atomic deformation of nt-Ni is closely related to the twin boundary:from the partial slips parallel to the twin boundary (~10 K),to increased confined layer slips and decreased twin migration(300 K–600 K),to decreased confined layer slips and increased dislocation interaction of dislocation pinning and dissociation (900 K–1200 K).Dislocation density and atomic structure types through quantitative analysis are implemented to further reveal the above-mentioned dislocation motion and atomic structure alteration.Our study is helpful for understanding the temperature-dependent plasticity of twin boundary in nanotwinned materials.