The effects of Ni addition and aging treatment on the microstructure and properties of Cu?3Ti alloy were investigated. Themicrostructure and phase constituents were characterized by optical microscopy, scanning electr...The effects of Ni addition and aging treatment on the microstructure and properties of Cu?3Ti alloy were investigated. Themicrostructure and phase constituents were characterized by optical microscopy, scanning electron microscopy, X-ray diffractometerand high-resolution transmission electron microscopy, and the hardness and electrical conductivity were measured as well. Theresults show that NiTi phase forms with addition of Ni into as-cast Cu-3Ti alloy during solidification, and the as-cast microstructureevolves from dentrite to equiaxial structure. After aging treatment, coherent metastable β′-Cu4Ti precipitates from the Cu matrix.However, β′-Cu4Ti precipitation phase transforms into equilibrium, incoherent and lamellar Cu3Ti phase after overaging. Meanwhile,aging treatment results in appearance of annealing twins in the residual NiTi phase, and dislocation lines exist in the Cu matrix. Niaddition enhances the electrical conductivity, but decreases the hardness of Cu?3Ti alloy. In the range of experiments, the optimumaging treatment for Cu?3Ti?1Ni alloy is 300 °C for 2 h and 450 °C for 7 h. The hardness and electrical conductivity were HV 205and 18.2%IACS (international annealed copper standard), respectively.展开更多
The effects of Ni addition and aging treatments on the microstructure and properties of a Cu–3Ti alloy were investigated. The microstructure and precipitation phases were characterized by X-ray diffraction, scanning ...The effects of Ni addition and aging treatments on the microstructure and properties of a Cu–3Ti alloy were investigated. The microstructure and precipitation phases were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy; the hardness, electrical conductivity, and elastic modulus of the resulting alloys were also tested. The results show that Ni addition increases the electrical conductivity and elastic modulus, but decreases the hardness of the aged Cu–3Ti alloy. Within the range of the experimentally investigated parameters, the optimal two-stage aging treatment for the Cu–3Ti–1Ni and Cu–3Ti–5Ni alloy was 300℃ for 2 h and 450℃ for 7 h. The hardness, electrical conductivity, and elastic modulus of the Cu–3Ti–1Ni alloy were HV 205, 18.2% IACS, and 146 GPa, respectively, whereas the hardness, electrical conductivity, and elastic modulus of the Cu–3Ti–5Ni alloy were HV 187, 31.32% IACS, and 147 GPa, respectively. Microstructural analyses revealed that β′-Ni3 Ti and β′-Cu4 Ti precipitate from the Cu matrix during aging of the Cu–3Ti–5Ni alloy and that some residual Ni Ti phase remains. The increased electrical conductivity is ascribed to the formation of Ni Ti, β′-Ni3 Ti, and β′-Cu4 Ti phases.展开更多
To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24...To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24 V/16 A under resistive load on an electric contact material testing system. The arc energy and arc duration were investigated, the surface morphologies of eroded anode and cathode were characterized, the mass changes after arc-erosion tests were determined, and the material transfer behavior was discussed as well. The results show that contact force has a significant effect on the arc energy, arc duration and erosion morphology, but has no impact on the material transfer mode. However, electrode gap not only influences the arc energy, arc duration and surface morphology, but also changes the material transfer mode. At 1 mm, the material transfers from anode to cathode. Nevertheless, an opposite mode presents at 4 mm, which is from cathode to anode.展开更多
Background:Mitochondria have been shown to play vital roles during severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection and coronavirus disease 2019(COVID-19)development.Currently,it is unclear whether...Background:Mitochondria have been shown to play vital roles during severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection and coronavirus disease 2019(COVID-19)development.Currently,it is unclear whether mitochondrial DNA(mtDNA)variants,which define mtDNA haplogroups and determine oxidative phosphorylation performance and reactive oxygen species production,are associated with COVID-19 risk.Methods:A population-based case-control study was conducted to compare the distribution of mtDNA variations defining mtDNA haplogroups between healthy controls(n=615)and COVID-19 patients(n=536).COVID-19 patients were diagnosed based on molecular diagnostics of the viral genome by qPCR and chest X-ray or computed tomography scanning.The exclusion criteria for the healthy controls were any history of disease in the month preceding the study assessment.MtDNA variants defining mtDNA haplogroups were identified by PCR-RFLPs and HVS-I sequencing and determined based on mtDNA phylogenetic analysis using Mitomap Phylogeny.Student’s t-test was used for continuous variables,and Pearson’s chi-squared test or Fisher’s exact test was used for categorical variables.To assess the independent effect of each mtDNA variant defining mtDNA haplogroups,multivariate logistic regression analyses were performed to calculate the odds ratios(OR)and 95%confidence intervals(CI)with adjustments for possible confounding factors of age,sex,smoking and diseases(including cardiopulmonary diseases,diabetes,obesity and hypertension)as determined through clinical and radiographic examinations.Results:Multivariate logistic regression analyses revealed that the most common investigated mtDNA variations(>10%in the control population)at C5178 a(in NADH dehydrogenase subunit 2 gene,ND2)and A249 d(in the displacement loop region,D-loop)/T6392 C(in cytochrome c oxidase I gene,CO1)/G10310 A(in ND3)were associated with a reduced risk of severe COVID-19(OR=0.590,95%CI 0.428–0.814,P=0.001;and OR=0.654,95%CI 0.457–0.936,P=0.020,respectively),while A4833 G(ND2),A4715 G(ND2),T3394 C(ND1)and G5417 A(ND2)/C16257 a(D-loop)/C16261 T(D-loop)were related to an increased risk of severe COVID-19(OR=2.336,95%CI 1.179–4.608,P=0.015;OR=2.033,95%CI 1.242–3.322,P=0.005;OR=3.040,95%CI 1.522–6.061,P=0.002;and OR=2.890,95%CI 1.199–6.993,P=0.018,respectively).Conclusions:This is the first study to explore the association of mtDNA variants with individual’s risk of developing severe COVID-19.Based on the case–control study,we concluded that the common mtDNA variants at C5178 a and A249 d/T6392 C/G10310 A might contribute to an individual’s resistance to developing severe COVID-19,whereas A4833 G,A4715 G,T3394 C and G5417 A/C16257 a/C16261 T might increase an individual’s risk of developing severe COVID-19.展开更多
Cryptochromes （CRYs） are blue and UV light photoreceptors, known to play key roles in circadian rhythms and in the light-dependent magnetosensitivity of insects. Two novel cryptochrome genes were cloned from the bro...Cryptochromes （CRYs） are blue and UV light photoreceptors, known to play key roles in circadian rhythms and in the light-dependent magnetosensitivity of insects. Two novel cryptochrome genes were cloned from the brown planthopper, and were given the designations of Nlcryl and Nlcry2, with the accession numbers KM108578 and KM108579 in GenBank. The complementary DNA sequences ofNlcryl andNlcry2 are 1935 bp and 2463 bp in length, and they contain an open reading frame of 1629 bp and 1872 bp, encoding amino acids of 542 and 623, with a predicted molecular weight of 62.53 kDa and 70.60 kDa, respectively. Well-conserved motifs such as DNA-photolyase and FAD-binding-7 domains were observed in Nlcry1 and Nlcry2. Phylogenetic analysis demonstrated the proteins of Nlcry1 and Nlcry2 to be clustered into the insect＇s cryptochrome 1 and cryptochrome 2, respectively. Quantitative polymerase chain reaction showed that the daily oscillations of messenger RNA （mRNA） expression in the head of the brown planthopper were mild for Nlcryl, and modest for Nlcry2. Throughout all developmental stages, Nlcryl and Nlcry2 exhibited extreme fluctuations and distinctive expression profiles. Cryptochrome mRNA expression peaked immediately after adult emergence and then decreased subsequently. The tissue expression profiles of newly emerged brown planthopper adults showed higher expression levels of CRYs in the head than in the thorax or abdomen, as well as significantly higher levels of CRYs in the heads of the macropterous strain than in the heads of the brachypterous strain. Taken together, the results of our study suggest that the two cryptochrome genes characterized in the brown planthopper might be associated with developmental physiology and migration.展开更多
Continuous jumping behavior,a kind of endurance locomotion,plays important roles in insect ecological adaption and survival.However,the methods used for the efficient evaluation of insect jumping behavior remain large...Continuous jumping behavior,a kind of endurance locomotion,plays important roles in insect ecological adaption and survival.However,the methods used for the efficient evaluation of insect jumping behavior remain largely lacking.Here,we developed a locomotion detection system named JumpDetector with automatic trajectory tracking and data analysis to evaluate the jumping of insects.This automated system exhibits more accurate,efficient,and adjustable performance than manual methods.By using this automatic system,we characterized a gradually declining pattern of continuous jumping behavior in 4th‐instar nymphs of the migratory locust.We found that locusts in their gregarious phase outperformed locusts in their solitary phase in the endurance jumping locomotion.Therefore,the JumpDetector could be widely used in jumping behavior and endurance locomotion measurement.展开更多
Eplgenetlc gene control is maintained by chromatln-assoclated Polycomb group (PcG)and Trithorax group (TrxG)genes,which act antagonistically via the interplay between PcG and TrxG regulation to generate silenced or pe...Eplgenetlc gene control is maintained by chromatln-assoclated Polycomb group (PcG)and Trithorax group (TrxG)genes,which act antagonistically via the interplay between PcG and TrxG regulation to generate silenced or permissive transcriptional states. In this study,we searched for PcG/TrxG genes in 180 arthropod genomes,covering all the sequenced arthropod genomes at the time of conducting this study,to perform a global investigation of PcG/TrxG genes in a phylogenetic frame.Results of ancestral state reconstruction analysis revealed that the ancestor of arthropod species has an almost complete repertoire of PcG/TrxG genes,and most of these genes were seldom lost above order level. The domain diversity analysis indicated that the PcG/TrxG genes show variable extent of domain structure changes;some of these changes could be associated with lineage-specific events.The likelihood ratio tests for selection pressure detected a number of PcG/TrxG genes which underwent episodic positive selection on the branch leading to the insects with holometabolous development.These results suggest that,despite their high conservation across arthropod species,different members of PcG/TrxG genes showed considerable differences in domain structure and sequence divergence in arthropod evolution.Our cross species comparisons using large-scale genomic data provide insights into divergent evolutionary pattern on highly conserved genes in arthropods.展开更多
The slab low-temperature reheating grain-oriented silicon steel was prepared in the laboratory,and the high-temperature annealing interruption tests were carried out.The effects of aluminum(which meant acid-soluble al...The slab low-temperature reheating grain-oriented silicon steel was prepared in the laboratory,and the high-temperature annealing interruption tests were carried out.The effects of aluminum(which meant acid-soluble aluminum)on the grain size texture,precipitate,magnetic properties and their correlations were studied.The results showed that with the increase in aluminum element,the grain size decreased,while the intensity of{114}<481>and{111}<112>textures increased in the primary recrystallization structure.Meanwhile,the pinning force during the secondary recrystallization and the onset secondary recrystallization temperature were increased.The precipitates were concluded to have a more important role on determining the onset secondary recrystallization temperature than the primary grain size.The higher onset temperature resulted in sharper Goss texture and the better magnetic properties,but when the aluminum content came up to a certain extent,a fine-grain structure was developed.The most suitable aluminum content for present study was 0.025 wt.%,while the onset secondary recrystallization temperature and the primary texture were considered to be conducive to the sharpness of Goss texture.展开更多
The electromagnetic field and flow analysis model were developed to simulate the electromagnetic field and the flow pattern in a vertical curved continuous slab caster with the in-roll type strand electromagnetic stir...The electromagnetic field and flow analysis model were developed to simulate the electromagnetic field and the flow pattern in a vertical curved continuous slab caster with the in-roll type strand electromagnetic stirring. The transient electromagnetic field distribution and the induced electromagnetic force were numerically described. The effects of stirring current, stirring frequency, and different stirrer configurations on the electromagnetically driven flow field in the strand were investigated and the optimization of the stirring parameters was discussed by performing a relative comparison of numerical results. Results show that the in-roller type strand electromagnetic stirrer （S- EMS） pair generates the fluctuating magnetic fields, penetrating through the cast slab and periodically parallel shift- ing along the slab wide face w!th time evolution. The transient induced electromagnetic forces travels toward the magnetic flux shifting direction, Different stirring parameters （i. e. current and frequency） and stirrer configurations affect the stirring strength and the flow rbcirculation pattern in the strand, which are closely related to metallurgical performances of the stirrers. There is an optimum frequency to obtain the maximum stirring. The present model pro vides a relatively theoretical insight into the in-roll type strand electromagnetic stirring system for best operating.展开更多
A mathematical model was developed to get an insight into 3D electromagnetic–thermal phenomena in an induction heated steel slab with a large width/thickness ratio by solving a fully coupled Maxwell equations and ene...A mathematical model was developed to get an insight into 3D electromagnetic–thermal phenomena in an induction heated steel slab with a large width/thickness ratio by solving a fully coupled Maxwell equations and energy conservation equation.The spatial heat radiation between the slab surface and the refractory wall in an induction furnace was considered.The electromagnetic induction and temperature distribution features inside the slab with time evolution were described.The effects of electromagnetic induction parameters,thermal conductivity of the material and process parameters on the induction heating process were theoretically examined.Numerical results show that the spatial distribution of induction heat generation inside the slab is non-uniform.The high work frequency and the low heat conductivity of slab increase the non-uniformity of slab induction heating process.The radiative heat loss and heat transfer between the slab and the metal parts used for holding the slab have an important effect on the slab surface temperature.It is necessary to separately control the current input in the multi-layer coil windings along the height direction of furnace and adopt the multi-step heating strategies with time evolution to improve the homogenization of the slab temperature.展开更多
Insects comprise the largest animal group in the world. More than a million insect species have been identified, leaving possibly two to three times more to be discovered. Systematic understanding of the genetic conte...Insects comprise the largest animal group in the world. More than a million insect species have been identified, leaving possibly two to three times more to be discovered. Systematic understanding of the genetic content of an insect species began more than 15 years ago when the genome sequence of the fruit fly, Drosophila melanogaster was reported （Adams et al., 2000）. For the first time, scientists were able to glean unprecedented insights into the genetic blueprint of a model insect, presenting its 13 600 protein coding genes. Such fundamental information opened a floodgate for comparative and functional analysis of these genes and enabled systems approaches to comparative, evolutionary and population genomic studies. In recent years, next-generation and third-generation sequencing platforms brought genome sequencing to more than a hundred insect species, reach- ing far beyond the few well-studied model organisms. The international consortium for insect genomes is work- ing toward an ambitious goal to sequence 5000 species of insects.展开更多
In lightweight automotive vehicles,the application of self-piercing rivet(SPR)joints is becoming increasingly widespread.Considering the importance of automotive service performance,the fatigue performance of SPR join...In lightweight automotive vehicles,the application of self-piercing rivet(SPR)joints is becoming increasingly widespread.Considering the importance of automotive service performance,the fatigue performance of SPR joints has received considerable attention.Therefore,this study proposes a data-driven approach to predict the fatigue life and failure modes of SPR joints.The dataset comprises three specimen types:cross-tensile,cross-peel,and tensile-shear.To ensure data consistency,a finite element analysis was employed to convert the external loads of the different specimens.Feature selection was implemented using various machine-learning algorithms to determine the model input.The Gaussian process regression algorithm was used to predict fatigue life,and its performance was compared with different kernel functions commonly used in the field.The results revealed that the Matern kernel exhibited an exceptional predictive capability for fatigue life.Among the data points,95.9%fell within the 3-fold error band,and the remaining 4.1%exceeded the 3-fold error band owing to inherent dispersion in the fatigue data.To predict the failure location,various tree and artificial neural network(ANN)models were compared.The findings indicated that the ANN models slightly outperformed the tree models.The ANN model accurately predicts the failure of joints with varying dimensions and materials.However,minor deviations were observed for the joints with the same sheet.Overall,this data-driven approach provided a reliable predictive model for estimating the fatigue life and failure location of SPR joints.展开更多
基金Projects(51201132,51274163) supported by the National Natural Science Foundation of ChinaProject(13JS076) supported by Shaanxi Provincial Key Laboratory Research Program,ChinaProject(2011HBSZS009) supported by Shaanxi Provincial Project of Special Foundation of Key Disciplines,China
文摘The effects of Ni addition and aging treatment on the microstructure and properties of Cu?3Ti alloy were investigated. Themicrostructure and phase constituents were characterized by optical microscopy, scanning electron microscopy, X-ray diffractometerand high-resolution transmission electron microscopy, and the hardness and electrical conductivity were measured as well. Theresults show that NiTi phase forms with addition of Ni into as-cast Cu-3Ti alloy during solidification, and the as-cast microstructureevolves from dentrite to equiaxial structure. After aging treatment, coherent metastable β′-Cu4Ti precipitates from the Cu matrix.However, β′-Cu4Ti precipitation phase transforms into equilibrium, incoherent and lamellar Cu3Ti phase after overaging. Meanwhile,aging treatment results in appearance of annealing twins in the residual NiTi phase, and dislocation lines exist in the Cu matrix. Niaddition enhances the electrical conductivity, but decreases the hardness of Cu?3Ti alloy. In the range of experiments, the optimumaging treatment for Cu?3Ti?1Ni alloy is 300 °C for 2 h and 450 °C for 7 h. The hardness and electrical conductivity were HV 205and 18.2%IACS (international annealed copper standard), respectively.
基金financially supported by the National Natural Science Foundation of China (Nos. 51201132 and 51274163)the Research Program of Shaanxi Provincial Key Laboratory (No. 13JS076)+1 种基金the China Scholarship Council, the Pivot Innovation Team of Shaanxi Electrical Materials and Infiltration Technique (No. 2012KCT-25)the Shaanxi Provincial Project of Special Foundation of Key Disciplines (No. 2011HBSZS009)
文摘The effects of Ni addition and aging treatments on the microstructure and properties of a Cu–3Ti alloy were investigated. The microstructure and precipitation phases were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy; the hardness, electrical conductivity, and elastic modulus of the resulting alloys were also tested. The results show that Ni addition increases the electrical conductivity and elastic modulus, but decreases the hardness of the aged Cu–3Ti alloy. Within the range of the experimentally investigated parameters, the optimal two-stage aging treatment for the Cu–3Ti–1Ni and Cu–3Ti–5Ni alloy was 300℃ for 2 h and 450℃ for 7 h. The hardness, electrical conductivity, and elastic modulus of the Cu–3Ti–1Ni alloy were HV 205, 18.2% IACS, and 146 GPa, respectively, whereas the hardness, electrical conductivity, and elastic modulus of the Cu–3Ti–5Ni alloy were HV 187, 31.32% IACS, and 147 GPa, respectively. Microstructural analyses revealed that β′-Ni3 Ti and β′-Cu4 Ti precipitate from the Cu matrix during aging of the Cu–3Ti–5Ni alloy and that some residual Ni Ti phase remains. The increased electrical conductivity is ascribed to the formation of Ni Ti, β′-Ni3 Ti, and β′-Cu4 Ti phases.
基金Projects(51274163,51605146) supported by the National Natural Science Foundation of ChinaProject(U1502274) supported by Key Program of the National Natural Science Foundation of China+2 种基金Project(2018M632769) supported by the China Postdoctoral Science FoundationProject(2017SKY-WK010) supported by the Research Fund of Shaanxi Key Laboratory of Comprehensive Utilization of Tailings Resources,ChinaProject(18JK0722) supported by Special Research Program of Shaanxi Provincial Department of Education,China
文摘To disclose the effect of contact force and electrode gap on the material transfer behavior of Ag-based contact material, arc-erosion tests of the Ag-4wt.%TiB2 contact material were performed for 5000 operations at 24 V/16 A under resistive load on an electric contact material testing system. The arc energy and arc duration were investigated, the surface morphologies of eroded anode and cathode were characterized, the mass changes after arc-erosion tests were determined, and the material transfer behavior was discussed as well. The results show that contact force has a significant effect on the arc energy, arc duration and erosion morphology, but has no impact on the material transfer mode. However, electrode gap not only influences the arc energy, arc duration and surface morphology, but also changes the material transfer mode. At 1 mm, the material transfers from anode to cathode. Nevertheless, an opposite mode presents at 4 mm, which is from cathode to anode.
基金supported by grants from the Special Project of Contingency Research for COVID-19(2020XGFYZR11)the Cultivating Project for Young Scholar at Hubei University of Medicine(2018QDJZR01)awarded to Dr.Fuyun Jithe Special Project of Contingency Research for COVID-19 at Hubei University of Medicine(2020XGFYZR03)。
文摘Background:Mitochondria have been shown to play vital roles during severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection and coronavirus disease 2019(COVID-19)development.Currently,it is unclear whether mitochondrial DNA(mtDNA)variants,which define mtDNA haplogroups and determine oxidative phosphorylation performance and reactive oxygen species production,are associated with COVID-19 risk.Methods:A population-based case-control study was conducted to compare the distribution of mtDNA variations defining mtDNA haplogroups between healthy controls(n=615)and COVID-19 patients(n=536).COVID-19 patients were diagnosed based on molecular diagnostics of the viral genome by qPCR and chest X-ray or computed tomography scanning.The exclusion criteria for the healthy controls were any history of disease in the month preceding the study assessment.MtDNA variants defining mtDNA haplogroups were identified by PCR-RFLPs and HVS-I sequencing and determined based on mtDNA phylogenetic analysis using Mitomap Phylogeny.Student’s t-test was used for continuous variables,and Pearson’s chi-squared test or Fisher’s exact test was used for categorical variables.To assess the independent effect of each mtDNA variant defining mtDNA haplogroups,multivariate logistic regression analyses were performed to calculate the odds ratios(OR)and 95%confidence intervals(CI)with adjustments for possible confounding factors of age,sex,smoking and diseases(including cardiopulmonary diseases,diabetes,obesity and hypertension)as determined through clinical and radiographic examinations.Results:Multivariate logistic regression analyses revealed that the most common investigated mtDNA variations(>10%in the control population)at C5178 a(in NADH dehydrogenase subunit 2 gene,ND2)and A249 d(in the displacement loop region,D-loop)/T6392 C(in cytochrome c oxidase I gene,CO1)/G10310 A(in ND3)were associated with a reduced risk of severe COVID-19(OR=0.590,95%CI 0.428–0.814,P=0.001;and OR=0.654,95%CI 0.457–0.936,P=0.020,respectively),while A4833 G(ND2),A4715 G(ND2),T3394 C(ND1)and G5417 A(ND2)/C16257 a(D-loop)/C16261 T(D-loop)were related to an increased risk of severe COVID-19(OR=2.336,95%CI 1.179–4.608,P=0.015;OR=2.033,95%CI 1.242–3.322,P=0.005;OR=3.040,95%CI 1.522–6.061,P=0.002;and OR=2.890,95%CI 1.199–6.993,P=0.018,respectively).Conclusions:This is the first study to explore the association of mtDNA variants with individual’s risk of developing severe COVID-19.Based on the case–control study,we concluded that the common mtDNA variants at C5178 a and A249 d/T6392 C/G10310 A might contribute to an individual’s resistance to developing severe COVID-19,whereas A4833 G,A4715 G,T3394 C and G5417 A/C16257 a/C16261 T might increase an individual’s risk of developing severe COVID-19.
基金We thank the staff in the Beijing READ BIO Bioinformatic Technology Company for their assistance in the phylogenetic inference and bioinformatic analysis of brown planthopper CRY proteins. This research was supported by the Key Program of National Natural Science of China （51037006）, the National Basic Research Program of China ＂973＂ （2010CB126200） and the National Nature Science Foundations of China （31170362, 31272051, 31470454 and 31070755）.
文摘Cryptochromes （CRYs） are blue and UV light photoreceptors, known to play key roles in circadian rhythms and in the light-dependent magnetosensitivity of insects. Two novel cryptochrome genes were cloned from the brown planthopper, and were given the designations of Nlcryl and Nlcry2, with the accession numbers KM108578 and KM108579 in GenBank. The complementary DNA sequences ofNlcryl andNlcry2 are 1935 bp and 2463 bp in length, and they contain an open reading frame of 1629 bp and 1872 bp, encoding amino acids of 542 and 623, with a predicted molecular weight of 62.53 kDa and 70.60 kDa, respectively. Well-conserved motifs such as DNA-photolyase and FAD-binding-7 domains were observed in Nlcry1 and Nlcry2. Phylogenetic analysis demonstrated the proteins of Nlcry1 and Nlcry2 to be clustered into the insect＇s cryptochrome 1 and cryptochrome 2, respectively. Quantitative polymerase chain reaction showed that the daily oscillations of messenger RNA （mRNA） expression in the head of the brown planthopper were mild for Nlcryl, and modest for Nlcry2. Throughout all developmental stages, Nlcryl and Nlcry2 exhibited extreme fluctuations and distinctive expression profiles. Cryptochrome mRNA expression peaked immediately after adult emergence and then decreased subsequently. The tissue expression profiles of newly emerged brown planthopper adults showed higher expression levels of CRYs in the head than in the thorax or abdomen, as well as significantly higher levels of CRYs in the heads of the macropterous strain than in the heads of the brachypterous strain. Taken together, the results of our study suggest that the two cryptochrome genes characterized in the brown planthopper might be associated with developmental physiology and migration.
基金This work was supported by the National Natural Science Foundation of China(Grant No.31772531 and 31601875)the Strategic Priority Program of CAS(Grant No.XDB11010000).
文摘Continuous jumping behavior,a kind of endurance locomotion,plays important roles in insect ecological adaption and survival.However,the methods used for the efficient evaluation of insect jumping behavior remain largely lacking.Here,we developed a locomotion detection system named JumpDetector with automatic trajectory tracking and data analysis to evaluate the jumping of insects.This automated system exhibits more accurate,efficient,and adjustable performance than manual methods.By using this automatic system,we characterized a gradually declining pattern of continuous jumping behavior in 4th‐instar nymphs of the migratory locust.We found that locusts in their gregarious phase outperformed locusts in their solitary phase in the endurance jumping locomotion.Therefore,the JumpDetector could be widely used in jumping behavior and endurance locomotion measurement.
基金the National Natural Science Foundation of China (Nos.31672353 and 31472047)The State Key Laboratory of Integrated Management of Pest Insects and Rodents (Grant No.ChineseIPM1708).
文摘Eplgenetlc gene control is maintained by chromatln-assoclated Polycomb group (PcG)and Trithorax group (TrxG)genes,which act antagonistically via the interplay between PcG and TrxG regulation to generate silenced or permissive transcriptional states. In this study,we searched for PcG/TrxG genes in 180 arthropod genomes,covering all the sequenced arthropod genomes at the time of conducting this study,to perform a global investigation of PcG/TrxG genes in a phylogenetic frame.Results of ancestral state reconstruction analysis revealed that the ancestor of arthropod species has an almost complete repertoire of PcG/TrxG genes,and most of these genes were seldom lost above order level. The domain diversity analysis indicated that the PcG/TrxG genes show variable extent of domain structure changes;some of these changes could be associated with lineage-specific events.The likelihood ratio tests for selection pressure detected a number of PcG/TrxG genes which underwent episodic positive selection on the branch leading to the insects with holometabolous development.These results suggest that,despite their high conservation across arthropod species,different members of PcG/TrxG genes showed considerable differences in domain structure and sequence divergence in arthropod evolution.Our cross species comparisons using large-scale genomic data provide insights into divergent evolutionary pattern on highly conserved genes in arthropods.
文摘The slab low-temperature reheating grain-oriented silicon steel was prepared in the laboratory,and the high-temperature annealing interruption tests were carried out.The effects of aluminum(which meant acid-soluble aluminum)on the grain size texture,precipitate,magnetic properties and their correlations were studied.The results showed that with the increase in aluminum element,the grain size decreased,while the intensity of{114}<481>and{111}<112>textures increased in the primary recrystallization structure.Meanwhile,the pinning force during the secondary recrystallization and the onset secondary recrystallization temperature were increased.The precipitates were concluded to have a more important role on determining the onset secondary recrystallization temperature than the primary grain size.The higher onset temperature resulted in sharper Goss texture and the better magnetic properties,but when the aluminum content came up to a certain extent,a fine-grain structure was developed.The most suitable aluminum content for present study was 0.025 wt.%,while the onset secondary recrystallization temperature and the primary texture were considered to be conducive to the sharpness of Goss texture.
文摘The electromagnetic field and flow analysis model were developed to simulate the electromagnetic field and the flow pattern in a vertical curved continuous slab caster with the in-roll type strand electromagnetic stirring. The transient electromagnetic field distribution and the induced electromagnetic force were numerically described. The effects of stirring current, stirring frequency, and different stirrer configurations on the electromagnetically driven flow field in the strand were investigated and the optimization of the stirring parameters was discussed by performing a relative comparison of numerical results. Results show that the in-roller type strand electromagnetic stirrer （S- EMS） pair generates the fluctuating magnetic fields, penetrating through the cast slab and periodically parallel shift- ing along the slab wide face w!th time evolution. The transient induced electromagnetic forces travels toward the magnetic flux shifting direction, Different stirring parameters （i. e. current and frequency） and stirrer configurations affect the stirring strength and the flow rbcirculation pattern in the strand, which are closely related to metallurgical performances of the stirrers. There is an optimum frequency to obtain the maximum stirring. The present model pro vides a relatively theoretical insight into the in-roll type strand electromagnetic stirring system for best operating.
文摘A mathematical model was developed to get an insight into 3D electromagnetic–thermal phenomena in an induction heated steel slab with a large width/thickness ratio by solving a fully coupled Maxwell equations and energy conservation equation.The spatial heat radiation between the slab surface and the refractory wall in an induction furnace was considered.The electromagnetic induction and temperature distribution features inside the slab with time evolution were described.The effects of electromagnetic induction parameters,thermal conductivity of the material and process parameters on the induction heating process were theoretically examined.Numerical results show that the spatial distribution of induction heat generation inside the slab is non-uniform.The high work frequency and the low heat conductivity of slab increase the non-uniformity of slab induction heating process.The radiative heat loss and heat transfer between the slab and the metal parts used for holding the slab have an important effect on the slab surface temperature.It is necessary to separately control the current input in the multi-layer coil windings along the height direction of furnace and adopt the multi-step heating strategies with time evolution to improve the homogenization of the slab temperature.
文摘Insects comprise the largest animal group in the world. More than a million insect species have been identified, leaving possibly two to three times more to be discovered. Systematic understanding of the genetic content of an insect species began more than 15 years ago when the genome sequence of the fruit fly, Drosophila melanogaster was reported （Adams et al., 2000）. For the first time, scientists were able to glean unprecedented insights into the genetic blueprint of a model insect, presenting its 13 600 protein coding genes. Such fundamental information opened a floodgate for comparative and functional analysis of these genes and enabled systems approaches to comparative, evolutionary and population genomic studies. In recent years, next-generation and third-generation sequencing platforms brought genome sequencing to more than a hundred insect species, reach- ing far beyond the few well-studied model organisms. The international consortium for insect genomes is work- ing toward an ambitious goal to sequence 5000 species of insects.
基金supported by the National Natural Science Foundation of China(Grant No.52205377)the Key Basic Research Project of Suzhou(Grant Nos.SJC2022029,SJC2022031)the National Key Research and Development Program(Grant No.2022YFB4601804).
文摘In lightweight automotive vehicles,the application of self-piercing rivet(SPR)joints is becoming increasingly widespread.Considering the importance of automotive service performance,the fatigue performance of SPR joints has received considerable attention.Therefore,this study proposes a data-driven approach to predict the fatigue life and failure modes of SPR joints.The dataset comprises three specimen types:cross-tensile,cross-peel,and tensile-shear.To ensure data consistency,a finite element analysis was employed to convert the external loads of the different specimens.Feature selection was implemented using various machine-learning algorithms to determine the model input.The Gaussian process regression algorithm was used to predict fatigue life,and its performance was compared with different kernel functions commonly used in the field.The results revealed that the Matern kernel exhibited an exceptional predictive capability for fatigue life.Among the data points,95.9%fell within the 3-fold error band,and the remaining 4.1%exceeded the 3-fold error band owing to inherent dispersion in the fatigue data.To predict the failure location,various tree and artificial neural network(ANN)models were compared.The findings indicated that the ANN models slightly outperformed the tree models.The ANN model accurately predicts the failure of joints with varying dimensions and materials.However,minor deviations were observed for the joints with the same sheet.Overall,this data-driven approach provided a reliable predictive model for estimating the fatigue life and failure location of SPR joints.
