We propose a nonlinear ultrasonic technique by using the mixed-frequency signals excited Lamb waves to conduct micro-crack detection in thin plate structures.Simulation models of three-dimensional(3D)aluminum plates a...We propose a nonlinear ultrasonic technique by using the mixed-frequency signals excited Lamb waves to conduct micro-crack detection in thin plate structures.Simulation models of three-dimensional(3D)aluminum plates and composite laminates are established by ABAQUS software,where the aluminum plate contains buried crack and composite laminates comprises cohesive element whose thickness is zero to simulate delamination damage.The interactions between the S0 mode Lamb wave and the buried micro-cracks of various dimensions are simulated by using the finite element method.Fourier frequency spectrum analysis is applied to the received time domain signal and fundamental frequency amplitudes,and sum and difference frequencies are extracted and simulated.Simulation results indicate that nonlinear Lamb waves have different sensitivities to various crack sizes.There is a positive correlation among crack length,height,and sum and difference frequency amplitudes for an aluminum plate,with both amplitudes decreasing as crack thickness increased,i.e.,nonlinear effect weakens as the micro-crack becomes thicker.The amplitudes of sum and difference frequency are positively correlated with the length and width of the zero-thickness cohesive element in the composite laminates.Furthermore,amplitude ratio change is investigated and it can be used as an effective tool to detect inner defects in thin 3D plates.展开更多
Objective:Using neuromyelitis optica immunoglobulin G(NMO-IgG)to induced ex vivo mice spinal cord slice model.Methods:Vibratome-cut transverse spinal cord slices from 7-day-old C57BL/6Jmouse pups were cultured on tran...Objective:Using neuromyelitis optica immunoglobulin G(NMO-IgG)to induced ex vivo mice spinal cord slice model.Methods:Vibratome-cut transverse spinal cord slices from 7-day-old C57BL/6Jmouse pups were cultured on transwell porous supports for 7days,then randomly divided into the control group and NMO model group.Slices of the control group were further cultured with human serum complement,while slices from NMO model group were exposed to complement and NMO-IgG.After 24-hour incubation,slices of both groups were measured for aquaporin-4(AQP4),glial fibrillary acidic protein(GFAP),myelin basic protein(MBP)and neurofilament light chain(NFL)by immunofluorescence.Results:Slices exposed to NMO-IgG showed astrocyte swelling,and a significant loss of AQP4and GFAP staining.Ratios of the loss of AQP4and GFAP staining were 77.74%±6.75%and 75.62%±5.76%respectively in the model group,and NMO-like injury score was 3.11±0.60.But there were no obvious losses of AQP4and GFAP staining in the control group,and NMO-like lesion score was 0.00.There were significant differences between the two groups with regards to the above indexes(P<0.01).Ratios of the loss of MBP and NFL staining in the model group were 37.60%±4.88%and46.29%±4.98%respectively,while the corresponding figures in the control group were 9.10%±1.63%and 5.80%±0.81%,and the differences between the two groups were statistically significant(P<0.01).Conclusion:These results suggested that NMO-IgG-induced ex vivo spinal cord slice model possesses typical features of NMO,and this model might be useful for relevant fundamental studies.展开更多
AIM:To analyze the differences,agreements,and correlation among total corneal power parameters generated by different instruments after myopic keratorefractive surgery.METHODS:The prospective cross-sectional study inc...AIM:To analyze the differences,agreements,and correlation among total corneal power parameters generated by different instruments after myopic keratorefractive surgery.METHODS:The prospective cross-sectional study included patients who underwent myopic keratorefractive surgery and received measurements of corneal power 3mo after surgery.Automated keratometer was used for the measurement of simulated keratometry(Sim K),sweptsource optical coherence tomography(SS-OCT)based biometer for total keratometry(TK),anterior segment-OCT for real keratometry(RK),and Scheimpflug keratometer for the true net power(TNP),the total corneal refractive power(TCRP)and equivalent K-readings(EKR).The differences among these parameters were analyzed,and the agreements and correlation between Sim K and other total corneal power parameters were investigated.RESULTS:A total of 70 eyes of 70 patients after myopic keratorefractive surgery were included.The evaluated corneal power parameters were as follows:Sim K 38.32±1.93 D,TK 37.54±2.12 D,RK 36.64±2.09 D,TNP 36.56±1.97 D,TCRP 36.70±2.01 D,and EKR 37.55±2.00 D.Pairwise comparison showed that there were significant differences(P<0.001)among all parameters except for between TK and EKR,RK and TNP,RK and TCRP(P=1.000,1.000,1.000,respectively).The limits of agreement between Sim K and TK,RK,TNP,TCPR,and EKR were 1.08,1.08,1.43,1.48,and 1.73 D,respectively.All parameters showed good correlation with Sim K,and the correlation coefficients were 0.995,0.994,0.983,0.982,and 0.975.CONCLUSION:Among the corneal power parameters after myopic keratorefractive surgery,the value of Sim K is the largest,followed by TK and EKR,with TCRP,RK,and TNP being the smallest.The differences among the parameters may be attributable to the different calculation principles.Correct understanding and evaluation of corneal power parameters can provide a theoretical basis for taking advantage of the total corneal power to improve the accuracy of intraocular lens calculation after keratorefractive surgery.展开更多
An underwater acoustic metasurface with sub-wavelength thickness is designed for acoustic wavefront manipulation.In this paper, a pentamode lattice and a frequency-independent generalized acoustic Snell's law are ...An underwater acoustic metasurface with sub-wavelength thickness is designed for acoustic wavefront manipulation.In this paper, a pentamode lattice and a frequency-independent generalized acoustic Snell's law are introduced to overcome the limitations of narrow bandwidth and low transmittance. The bulk modulus and effective density of each unit cell can be tuned simultaneously, which are modulated to guarantee the achievement of refractive index profile and high transmission. Here, we actualize anomalous refraction, generation of non-diffracting Bessel beam, sub-wavelength flat focusing,and surface wave conversion by constructing inhomogeneous acoustic metasurface. This design approach has potential applications in medical ultrasound imaging and underwater acoustic communications.展开更多
We report pulsar timing observations carried out in L-band with NTSC’s 40-meter Haoping Radio Telescope(HRT),which was constructed in 2014.These observations were carried out using the pulsar machine we developed.Tim...We report pulsar timing observations carried out in L-band with NTSC’s 40-meter Haoping Radio Telescope(HRT),which was constructed in 2014.These observations were carried out using the pulsar machine we developed.Timing observations toward millisecond pulsar J0437–4715 obtain a timing residual(r.m.s.)of 397 ns in the time span of 284 days.Our observations successfully detected Crab pulsar’s glitch that happened on 2019 July 23.展开更多
In the present work,surface mechanical attrition treatment(SMAT)was proposed to achieve surface nanocrystallization on Ti-6Al-4V surface via high-energy planetary ball milling method using a planetary ball mill.The ch...In the present work,surface mechanical attrition treatment(SMAT)was proposed to achieve surface nanocrystallization on Ti-6Al-4V surface via high-energy planetary ball milling method using a planetary ball mill.The characteristics of microstructure were studied using different methods.Surface nanocrystallization is achieved on Ti-6Al-4V substrate.The process of refinement could be summarized into four steps.During the refinement process,the reticular continuous beta phase performs a significant role,it cracked,broke up and moved to each side along the grain boundaries.The movement of beta grains has the capabilities of effectively optimizing the grain orientation and accelerating the further refinement of alpha grains.Twinning also plays an important role during the refinement.The grain orientation between different types of grains seems to be larger than that of same type grains.The interface will be divided into smaller nanocrystalline grains once the dislocation density breaks the threshold.Then,the balance will be achieved again and owns a higher critical value which cannot be broken,then a stable grain size can be achieved ultimately.The results of microhardness,friction coefficient and wear mass loss tests of SMAT samples indicate that the mechanical behaviors of substrate are greatly enhanced after this novel SMAT treatment.展开更多
Bearings are one of the most important components in modern industry.Rolling contact fatigue(RCF)initiating from surface and subsurface is the major failure mode.In this paper,a typical high speed thrust angular conta...Bearings are one of the most important components in modern industry.Rolling contact fatigue(RCF)initiating from surface and subsurface is the major failure mode.In this paper,a typical high speed thrust angular contact ball bearing was selected,and the machined surface quality and near-surface microstructure of the race-way and rolling ball were systematically characterized by using of a probe surface profiler,white light interferometer,optical microscopy(OM),scanning electron microscopy(SEM),electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM)combined with focused ion beam(FIB).Two kinds of precursor,probably resulting in pitting or spalling during the following rolling contact,were detected.One is the defects on the surface of either the race-way or the rolling ball,such as heavy machining marks,scratches and slag-hole.The other is nano-crystalline layer due to machining,in the outermost layer around the surface of race-way.The results may well lay foundation for our further research on RCF with the real part of such typical rolling bearings.展开更多
One antibacterial activity fraction from an immunized dipteran insect, Bactrocera dorsalis, was isolated and purified by prepurification, ion-exchange chromatography, gel filtration chromatography and reverse-phase hi...One antibacterial activity fraction from an immunized dipteran insect, Bactrocera dorsalis, was isolated and purified by prepurification, ion-exchange chromatography, gel filtration chromatography and reverse-phase high performance liquid chromatography (HPLC). The final purified fraction was checked on the Smart system HPLC and was judged as a pure fraction. The results of physical and biological analysis revealed that this fraction is heat stable and showed strong activities against Gram-positive bacterial growth. It possesses antibicrobial peptide properties and is worth further investigation.展开更多
Background::Rectal cancer(RC)is a malignant tumor that seriously threatens human health.Long non-coding RNAs(lncRNAs)play a vital role in tumor regulation.Nevertheless,their exact expression features and functions rem...Background::Rectal cancer(RC)is a malignant tumor that seriously threatens human health.Long non-coding RNAs(lncRNAs)play a vital role in tumor regulation.Nevertheless,their exact expression features and functions remain obscure,and therefore was the aim of the current study.Methods::We utilized the Affymetrix human GeneChip to screen differentially expressed profiles of lncRNAs and mRNAs from the cancer tissues and matched paracancer tissues of 6 RC patients.Gene Ontology(GO)and pathway enrichment analyses identified crucial functions and pathways of the aberrantly expressed mRNAs.We used quantitative real-time polymerase chain reaction to verify the significant expression differences of 11 candidate lncRNAs between the cancer and paracancer tissues.LncRNA-mRNA coexpression networks were built by calculating the Pearson correlation value to identify significant correlation pairs.Online bioinformatics tools GEPIA2,ONCOMINE,and PROGgeneV2 were used to mine the expression and prognosis of three crucial mRNAs and six verified lncRNAs.Competing endogenous RNA networks were constructed by predicting microRNA response elements and calculating free energy.Results::We found 1658 differentially expressed lncRNAs(778 up-regulated and 880 down-regulated)and 1783 aberrantly expressed mRNAs(909 up-regulated and 874 down-regulated).GO and pathway enrichment analyses revealed the vital functions of the differentially expressed mRNAs,including cell proliferation,cell migration,angiogenesis,and cellular response to zinc ion.The canonical signaling pathways mainly included the interleukin-17,cell cycle,Wnt,and mineral absorption signaling pathways.Six lncRNAs including AC017002.2(P=0.039),cancer susceptibility 19(CASC19)(P=0.021),LINC00152(P=0.013),NONHSAT058834(P=0.007),NONHSAT007692(P=0.045),and ENST00000415991.1(P=0.045)showed significant differences in expression levels between the cancer tissue and paracancer tissue groups.AC017002.2,NONHSAT058834,NONHSAT007692,and ENST00000415991.1 have not yet been reported in RC.The crucial mRNAs myelocytomatosis viral oncogene(MYC),transforming growth factor beta induced(TGFBI),and solute carrier family 7 member 5(SLC7A5)were selected.AC017002.2 and LINC00152 were positively correlated with MYC,TGFBI,and cytochrome P450 family 2 sub-family B member 6(All r>0.900,P<0.050).NONHSAT058834 was positively associated with MYC(r=0.930,P<0.001),and CASC19 was positively correlated with SLC7A5(r=0.922,P<0.001).Conclusion::This study offers convincing evidence of differentially expressed lncRNAs and mRNAs as potential biomarkers in RC.展开更多
Background:With the closure of the Three Gorges Dam in 2003 the hydrology of Poyang Lake was altered dramatically leading to significant changes in the environment.In order to assess the impact on schistosomiasis this...Background:With the closure of the Three Gorges Dam in 2003 the hydrology of Poyang Lake was altered dramatically leading to significant changes in the environment.In order to assess the impact on schistosomiasis this study assessed the spatial and temporal patterns of the snail intermediate host,Oncomelania hupensis in the Poyang Lake tributaries.The results of the study have important implications for future snail control strategies leading to disease elimination.Methods:The marshland area surrounding Poyang Lake was divided randomly into 200×200 m vector grids using ArcGIS software,and the surveyed grids were randomly selected by the software.The snail survey was conducted in each selected grid using a survey frame of 50×50 m with one sideline of each grid serving as the starting line.No less than ten frames were used in each surveyed grid with Global Positioning System(GPS)recordings for each.All snails in each frame were collected to determine infection status by microscopy.Altitude data for all frames were extracted from a lake bottom topographic map in order to analyze the average altitude.All snail survey data were collected and statistically analyzed with SPSS 20.0 software in order to determine the difference of the percentage of frames with living snails and mean density of living snails in different regions of Poyang Lake.The altitude of the snail-infested marshlands and snail dens were subsequently identified.Results:A total of 1159 potential snail sampling grids were surveyed,of which 15231 frames(0.1 m2/frame)were investigated.1241 frames had live Oncomelania snails corresponding to 8.15%of the total number of frames.The mean density of living snails was 0.463/0.1 m2 with a maximum of 57 snails per frame.The percent of frames with snails in the southern sector(8.13%)of Poyang Lake did not differ statistically from the north(8.21%).However,the mean density of live snails in the northern sector(0.164/0.1 m2)of the lake was statistically higher(F=6.727;P=0.010)than the south(0.141/0.1 m2).In the south of the lake,the elevation of snail-inhabited marshland ranged between 11-16 m,and could be further subdivided into two snail-concentrated belts at 12-13 m of elevation and 15-16 m of elevation respectively.In the north of the lake,the elevation of snail-inhabited marshland ranged between 9-16 m with the elevation of 12-14 m being the snail-concentrated zone.Conclusions:The elevation of snail-infested marshlands in the Poyang Lake region ranged from 9 to 16 m.The snail distribution and habitat has moved north of the lake and to a lower altitude due to changes in the water level post dam closure.Based on the current geological features of the snail habitant focused mollusciciding should occur in snail dense northern regions with frequent bovine and human traffic.Targeting these identified'hotspots'of transmission will assist in elimination efforts.展开更多
Two types of cascading decomposition problems of Boolean control networks are investigated using a graph-theoretical method.A new graphic concept called nested perfect equal vertex partition(NPEVP)is proposed.Based on...Two types of cascading decomposition problems of Boolean control networks are investigated using a graph-theoretical method.A new graphic concept called nested perfect equal vertex partition(NPEVP)is proposed.Based on NPEVP,the necessary and sufficient graphic conditions for solvability of the cascading decomposition problems are obtained.Given the proposed graphic conditions,the logical coordinate transformations are constructively obtained to realize the corresponding cascading decomposition forms.Finally,two illustrative examples are provided to validate the results.展开更多
Background Oncomelania hupensis is the only intermediate host of Schistosoma japonicum and plays a decisive role in its transmission.The variation of water level greatly affects the reproduction and growth of snails.T...Background Oncomelania hupensis is the only intermediate host of Schistosoma japonicum and plays a decisive role in its transmission.The variation of water level greatly affects the reproduction and growth of snails.Therefore,in this paper,we analyze the variations of water level in the Poyang Lake region from 1993 to 2016 combined with satellite imagery to elucidate the evolution of the snail breeding environment.Methods By employing remote sensing data from 1993 to 2016(April–June and September–November),the vegetation area of Poyang Lake and the vegetation area at different elevations were extracted and calculated.Moreover,the average daily water level data from the four hydrological stations(Hukou station,Xingzi station,Tangyin station and Kangshan station)which represent the typical state of Poyang Lake were collected from 1993 to 2016.The variance of the monthly mean water level,inundation time and the average area were analyzed by variance to find a significance level ofα=0.05.Results According to hydrological data before and after 2003,the average water level after 2003 is significantly lower than that before 2003 in Poyang Lake.After 2003,the time of inundateing the snail breeding period was later in April to June than that before 2003,while the time of wate-falling stage in September to November moved forward after 2003 than before 2003.Of them,the lowest water level affecting the breeding and growing period of O.hupensis in the northern part of Poyang Lake decreased from 11 m to 9 m.After 2003,the expansion of meadow area in the north part of Poyang Lake was mainly concentrated in the elevation of 9–11 m,and the newly increased infested-meadow in the lake area was mainly concentrated in the north part of Poyang Lake.Conclusions By comparing the change of water level characteristics in different parts of the Poyang Lake area as well as changes in meadow area before and after 2003,it is found that the water level changes mainly affect the snail breeding area in the northern part of Poyang Lake.The results are helpful for improving scientific measures for snail control in Jiangxi Province.This approach could also be applicible to Dongting Lake area and other lake areas affected by water level changes and can bring significant guidance for snail control in lake areas.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61571222,61602235,and 11474160)the Six Talent Peaks Project of Jiangsu Province,China
文摘We propose a nonlinear ultrasonic technique by using the mixed-frequency signals excited Lamb waves to conduct micro-crack detection in thin plate structures.Simulation models of three-dimensional(3D)aluminum plates and composite laminates are established by ABAQUS software,where the aluminum plate contains buried crack and composite laminates comprises cohesive element whose thickness is zero to simulate delamination damage.The interactions between the S0 mode Lamb wave and the buried micro-cracks of various dimensions are simulated by using the finite element method.Fourier frequency spectrum analysis is applied to the received time domain signal and fundamental frequency amplitudes,and sum and difference frequencies are extracted and simulated.Simulation results indicate that nonlinear Lamb waves have different sensitivities to various crack sizes.There is a positive correlation among crack length,height,and sum and difference frequency amplitudes for an aluminum plate,with both amplitudes decreasing as crack thickness increased,i.e.,nonlinear effect weakens as the micro-crack becomes thicker.The amplitudes of sum and difference frequency are positively correlated with the length and width of the zero-thickness cohesive element in the composite laminates.Furthermore,amplitude ratio change is investigated and it can be used as an effective tool to detect inner defects in thin 3D plates.
基金supported by the National Natural Science Foundation of China (No.81460194 No.81260188)
文摘Objective:Using neuromyelitis optica immunoglobulin G(NMO-IgG)to induced ex vivo mice spinal cord slice model.Methods:Vibratome-cut transverse spinal cord slices from 7-day-old C57BL/6Jmouse pups were cultured on transwell porous supports for 7days,then randomly divided into the control group and NMO model group.Slices of the control group were further cultured with human serum complement,while slices from NMO model group were exposed to complement and NMO-IgG.After 24-hour incubation,slices of both groups were measured for aquaporin-4(AQP4),glial fibrillary acidic protein(GFAP),myelin basic protein(MBP)and neurofilament light chain(NFL)by immunofluorescence.Results:Slices exposed to NMO-IgG showed astrocyte swelling,and a significant loss of AQP4and GFAP staining.Ratios of the loss of AQP4and GFAP staining were 77.74%±6.75%and 75.62%±5.76%respectively in the model group,and NMO-like injury score was 3.11±0.60.But there were no obvious losses of AQP4and GFAP staining in the control group,and NMO-like lesion score was 0.00.There were significant differences between the two groups with regards to the above indexes(P<0.01).Ratios of the loss of MBP and NFL staining in the model group were 37.60%±4.88%and46.29%±4.98%respectively,while the corresponding figures in the control group were 9.10%±1.63%and 5.80%±0.81%,and the differences between the two groups were statistically significant(P<0.01).Conclusion:These results suggested that NMO-IgG-induced ex vivo spinal cord slice model possesses typical features of NMO,and this model might be useful for relevant fundamental studies.
基金Supported by the Hospital Founding of Beijing Tongren Hospital(No.2021-YJJ-PY-002)。
文摘AIM:To analyze the differences,agreements,and correlation among total corneal power parameters generated by different instruments after myopic keratorefractive surgery.METHODS:The prospective cross-sectional study included patients who underwent myopic keratorefractive surgery and received measurements of corneal power 3mo after surgery.Automated keratometer was used for the measurement of simulated keratometry(Sim K),sweptsource optical coherence tomography(SS-OCT)based biometer for total keratometry(TK),anterior segment-OCT for real keratometry(RK),and Scheimpflug keratometer for the true net power(TNP),the total corneal refractive power(TCRP)and equivalent K-readings(EKR).The differences among these parameters were analyzed,and the agreements and correlation between Sim K and other total corneal power parameters were investigated.RESULTS:A total of 70 eyes of 70 patients after myopic keratorefractive surgery were included.The evaluated corneal power parameters were as follows:Sim K 38.32±1.93 D,TK 37.54±2.12 D,RK 36.64±2.09 D,TNP 36.56±1.97 D,TCRP 36.70±2.01 D,and EKR 37.55±2.00 D.Pairwise comparison showed that there were significant differences(P<0.001)among all parameters except for between TK and EKR,RK and TNP,RK and TCRP(P=1.000,1.000,1.000,respectively).The limits of agreement between Sim K and TK,RK,TNP,TCPR,and EKR were 1.08,1.08,1.43,1.48,and 1.73 D,respectively.All parameters showed good correlation with Sim K,and the correlation coefficients were 0.995,0.994,0.983,0.982,and 0.975.CONCLUSION:Among the corneal power parameters after myopic keratorefractive surgery,the value of Sim K is the largest,followed by TK and EKR,with TCRP,RK,and TNP being the smallest.The differences among the parameters may be attributable to the different calculation principles.Correct understanding and evaluation of corneal power parameters can provide a theoretical basis for taking advantage of the total corneal power to improve the accuracy of intraocular lens calculation after keratorefractive surgery.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61571222 and 11474160)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20161009)the Six-Talent Peaks Project of Jiangsu Province,China
文摘An underwater acoustic metasurface with sub-wavelength thickness is designed for acoustic wavefront manipulation.In this paper, a pentamode lattice and a frequency-independent generalized acoustic Snell's law are introduced to overcome the limitations of narrow bandwidth and low transmittance. The bulk modulus and effective density of each unit cell can be tuned simultaneously, which are modulated to guarantee the achievement of refractive index profile and high transmission. Here, we actualize anomalous refraction, generation of non-diffracting Bessel beam, sub-wavelength flat focusing,and surface wave conversion by constructing inhomogeneous acoustic metasurface. This design approach has potential applications in medical ultrasound imaging and underwater acoustic communications.
基金supported by the Hundred Talents Program of the Chinese Academy of Sciences(Technological excellence,Y650YC1201)the National Natural Science Foundation of China(Grant Nos.U1931128,11973046,91736207,U1831130,11903038,11873050 and 11873049)+1 种基金The Natural Science Foundation of Shaanxi Province(Grant No.2019JM455)the program of Youth Innovation Promotion Association CAS(2017450).
文摘We report pulsar timing observations carried out in L-band with NTSC’s 40-meter Haoping Radio Telescope(HRT),which was constructed in 2014.These observations were carried out using the pulsar machine we developed.Timing observations toward millisecond pulsar J0437–4715 obtain a timing residual(r.m.s.)of 397 ns in the time span of 284 days.Our observations successfully detected Crab pulsar’s glitch that happened on 2019 July 23.
基金the support of National Natural Science Foundation of China (Nos. 22172020 and 61974020)supported by the projects of Sci & Tech planning of Zhuhai City (No. ZH22017001200032PWC)Sichuan Science and Technology Program (No. 2022YFS0527)。
基金financially supported by the National Natural Science Foundation of China(No.51475232)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD,Basic Research on Metal Surface Modification by Surface Mechanical Attrition Treatment)the Foundation of Graduate Innovation Center in NUAA and the Fundamental Research Funds for the Central Universities(No.Kfjj20150605)。
文摘In the present work,surface mechanical attrition treatment(SMAT)was proposed to achieve surface nanocrystallization on Ti-6Al-4V surface via high-energy planetary ball milling method using a planetary ball mill.The characteristics of microstructure were studied using different methods.Surface nanocrystallization is achieved on Ti-6Al-4V substrate.The process of refinement could be summarized into four steps.During the refinement process,the reticular continuous beta phase performs a significant role,it cracked,broke up and moved to each side along the grain boundaries.The movement of beta grains has the capabilities of effectively optimizing the grain orientation and accelerating the further refinement of alpha grains.Twinning also plays an important role during the refinement.The grain orientation between different types of grains seems to be larger than that of same type grains.The interface will be divided into smaller nanocrystalline grains once the dislocation density breaks the threshold.Then,the balance will be achieved again and owns a higher critical value which cannot be broken,then a stable grain size can be achieved ultimately.The results of microhardness,friction coefficient and wear mass loss tests of SMAT samples indicate that the mechanical behaviors of substrate are greatly enhanced after this novel SMAT treatment.
基金funded by the Strategic Priority Research Program of the Chinese Academy of Sciences,China through Projects No.XDC04030400。
文摘Bearings are one of the most important components in modern industry.Rolling contact fatigue(RCF)initiating from surface and subsurface is the major failure mode.In this paper,a typical high speed thrust angular contact ball bearing was selected,and the machined surface quality and near-surface microstructure of the race-way and rolling ball were systematically characterized by using of a probe surface profiler,white light interferometer,optical microscopy(OM),scanning electron microscopy(SEM),electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM)combined with focused ion beam(FIB).Two kinds of precursor,probably resulting in pitting or spalling during the following rolling contact,were detected.One is the defects on the surface of either the race-way or the rolling ball,such as heavy machining marks,scratches and slag-hole.The other is nano-crystalline layer due to machining,in the outermost layer around the surface of race-way.The results may well lay foundation for our further research on RCF with the real part of such typical rolling bearings.
基金Acknowledgments We thank Prof. X.-F. Pang, late Academician of Chinese Academy of Science, for his support in getting this project started. We also thank Prof. Yamakawa (National of Institute of Sericultural and Entomological Science, Japan) for analyzing the purity of the final purified fraction. We thank Dr H. Ma for his suggestions on this project and reading our manuscript. This work was supported partly by the Natural Science Foundation of Guangdong Province (032256), the National Basic Research Program of China under grant 2005CB121000 and the National Natural Science Foundation (30370716).
文摘One antibacterial activity fraction from an immunized dipteran insect, Bactrocera dorsalis, was isolated and purified by prepurification, ion-exchange chromatography, gel filtration chromatography and reverse-phase high performance liquid chromatography (HPLC). The final purified fraction was checked on the Smart system HPLC and was judged as a pure fraction. The results of physical and biological analysis revealed that this fraction is heat stable and showed strong activities against Gram-positive bacterial growth. It possesses antibicrobial peptide properties and is worth further investigation.
基金This work was supported by a grant from the Beijing Municipal Health Commission’s Key Clinical Specialty(Oncology)(Project No.2018ZLLCZDZK1).
文摘Background::Rectal cancer(RC)is a malignant tumor that seriously threatens human health.Long non-coding RNAs(lncRNAs)play a vital role in tumor regulation.Nevertheless,their exact expression features and functions remain obscure,and therefore was the aim of the current study.Methods::We utilized the Affymetrix human GeneChip to screen differentially expressed profiles of lncRNAs and mRNAs from the cancer tissues and matched paracancer tissues of 6 RC patients.Gene Ontology(GO)and pathway enrichment analyses identified crucial functions and pathways of the aberrantly expressed mRNAs.We used quantitative real-time polymerase chain reaction to verify the significant expression differences of 11 candidate lncRNAs between the cancer and paracancer tissues.LncRNA-mRNA coexpression networks were built by calculating the Pearson correlation value to identify significant correlation pairs.Online bioinformatics tools GEPIA2,ONCOMINE,and PROGgeneV2 were used to mine the expression and prognosis of three crucial mRNAs and six verified lncRNAs.Competing endogenous RNA networks were constructed by predicting microRNA response elements and calculating free energy.Results::We found 1658 differentially expressed lncRNAs(778 up-regulated and 880 down-regulated)and 1783 aberrantly expressed mRNAs(909 up-regulated and 874 down-regulated).GO and pathway enrichment analyses revealed the vital functions of the differentially expressed mRNAs,including cell proliferation,cell migration,angiogenesis,and cellular response to zinc ion.The canonical signaling pathways mainly included the interleukin-17,cell cycle,Wnt,and mineral absorption signaling pathways.Six lncRNAs including AC017002.2(P=0.039),cancer susceptibility 19(CASC19)(P=0.021),LINC00152(P=0.013),NONHSAT058834(P=0.007),NONHSAT007692(P=0.045),and ENST00000415991.1(P=0.045)showed significant differences in expression levels between the cancer tissue and paracancer tissue groups.AC017002.2,NONHSAT058834,NONHSAT007692,and ENST00000415991.1 have not yet been reported in RC.The crucial mRNAs myelocytomatosis viral oncogene(MYC),transforming growth factor beta induced(TGFBI),and solute carrier family 7 member 5(SLC7A5)were selected.AC017002.2 and LINC00152 were positively correlated with MYC,TGFBI,and cytochrome P450 family 2 sub-family B member 6(All r>0.900,P<0.050).NONHSAT058834 was positively associated with MYC(r=0.930,P<0.001),and CASC19 was positively correlated with SLC7A5(r=0.922,P<0.001).Conclusion::This study offers convincing evidence of differentially expressed lncRNAs and mRNAs as potential biomarkers in RC.
基金the National Natural Science Foundation of China(grant No.81660557,71764011)Jiangxi Province Focus on Research and Development Plan(grant No.20171BBG70105).
文摘Background:With the closure of the Three Gorges Dam in 2003 the hydrology of Poyang Lake was altered dramatically leading to significant changes in the environment.In order to assess the impact on schistosomiasis this study assessed the spatial and temporal patterns of the snail intermediate host,Oncomelania hupensis in the Poyang Lake tributaries.The results of the study have important implications for future snail control strategies leading to disease elimination.Methods:The marshland area surrounding Poyang Lake was divided randomly into 200×200 m vector grids using ArcGIS software,and the surveyed grids were randomly selected by the software.The snail survey was conducted in each selected grid using a survey frame of 50×50 m with one sideline of each grid serving as the starting line.No less than ten frames were used in each surveyed grid with Global Positioning System(GPS)recordings for each.All snails in each frame were collected to determine infection status by microscopy.Altitude data for all frames were extracted from a lake bottom topographic map in order to analyze the average altitude.All snail survey data were collected and statistically analyzed with SPSS 20.0 software in order to determine the difference of the percentage of frames with living snails and mean density of living snails in different regions of Poyang Lake.The altitude of the snail-infested marshlands and snail dens were subsequently identified.Results:A total of 1159 potential snail sampling grids were surveyed,of which 15231 frames(0.1 m2/frame)were investigated.1241 frames had live Oncomelania snails corresponding to 8.15%of the total number of frames.The mean density of living snails was 0.463/0.1 m2 with a maximum of 57 snails per frame.The percent of frames with snails in the southern sector(8.13%)of Poyang Lake did not differ statistically from the north(8.21%).However,the mean density of live snails in the northern sector(0.164/0.1 m2)of the lake was statistically higher(F=6.727;P=0.010)than the south(0.141/0.1 m2).In the south of the lake,the elevation of snail-inhabited marshland ranged between 11-16 m,and could be further subdivided into two snail-concentrated belts at 12-13 m of elevation and 15-16 m of elevation respectively.In the north of the lake,the elevation of snail-inhabited marshland ranged between 9-16 m with the elevation of 12-14 m being the snail-concentrated zone.Conclusions:The elevation of snail-infested marshlands in the Poyang Lake region ranged from 9 to 16 m.The snail distribution and habitat has moved north of the lake and to a lower altitude due to changes in the water level post dam closure.Based on the current geological features of the snail habitant focused mollusciciding should occur in snail dense northern regions with frequent bovine and human traffic.Targeting these identified'hotspots'of transmission will assist in elimination efforts.
基金Project supported by the National Natural Science Foundation of China(No.61673012)。
文摘Two types of cascading decomposition problems of Boolean control networks are investigated using a graph-theoretical method.A new graphic concept called nested perfect equal vertex partition(NPEVP)is proposed.Based on NPEVP,the necessary and sufficient graphic conditions for solvability of the cascading decomposition problems are obtained.Given the proposed graphic conditions,the logical coordinate transformations are constructively obtained to realize the corresponding cascading decomposition forms.Finally,two illustrative examples are provided to validate the results.
文摘Background Oncomelania hupensis is the only intermediate host of Schistosoma japonicum and plays a decisive role in its transmission.The variation of water level greatly affects the reproduction and growth of snails.Therefore,in this paper,we analyze the variations of water level in the Poyang Lake region from 1993 to 2016 combined with satellite imagery to elucidate the evolution of the snail breeding environment.Methods By employing remote sensing data from 1993 to 2016(April–June and September–November),the vegetation area of Poyang Lake and the vegetation area at different elevations were extracted and calculated.Moreover,the average daily water level data from the four hydrological stations(Hukou station,Xingzi station,Tangyin station and Kangshan station)which represent the typical state of Poyang Lake were collected from 1993 to 2016.The variance of the monthly mean water level,inundation time and the average area were analyzed by variance to find a significance level ofα=0.05.Results According to hydrological data before and after 2003,the average water level after 2003 is significantly lower than that before 2003 in Poyang Lake.After 2003,the time of inundateing the snail breeding period was later in April to June than that before 2003,while the time of wate-falling stage in September to November moved forward after 2003 than before 2003.Of them,the lowest water level affecting the breeding and growing period of O.hupensis in the northern part of Poyang Lake decreased from 11 m to 9 m.After 2003,the expansion of meadow area in the north part of Poyang Lake was mainly concentrated in the elevation of 9–11 m,and the newly increased infested-meadow in the lake area was mainly concentrated in the north part of Poyang Lake.Conclusions By comparing the change of water level characteristics in different parts of the Poyang Lake area as well as changes in meadow area before and after 2003,it is found that the water level changes mainly affect the snail breeding area in the northern part of Poyang Lake.The results are helpful for improving scientific measures for snail control in Jiangxi Province.This approach could also be applicible to Dongting Lake area and other lake areas affected by water level changes and can bring significant guidance for snail control in lake areas.