A comprehensive investigation was conducted to explore the degradation mechanism of leakage current in SiC junction barrier Schottky(JBS)diodes under heavy ion irradiation.We propose and verify that the generation of ...A comprehensive investigation was conducted to explore the degradation mechanism of leakage current in SiC junction barrier Schottky(JBS)diodes under heavy ion irradiation.We propose and verify that the generation of stacking faults(SFs)induced by the recombination of massive electron-hole pairs during irradiation is the cause of reverse leakage current degradation based on experiments results.The irradiation experiment was carried out based on Ta ions with high linear energy transfer(LET)of 90.5 MeV/(mg/cm^(2)).It is observed that the leakage current of the diode undergoes the permanent increase during irradiation when biased at 20%of the rated reverse voltage.Micro-PL spectroscopy and PL micro-imaging were utilized to detect the presence of SFs in the irradiated SiC JBS diodes.We combined the degraded performance of irradiated samples with SFs introduced by heavy ion irradiation.Finally,three-dimensional(3D)TCAD simulation was employed to evaluate the excessive electron-hole pairs(EHPs)concentration excited by heavy ion irradiation.It was observed that the excessive hole concentration under irradiation exceeded significantly the threshold hole concentration necessary for the expansion of SFs in the substrate.The proposed mechanism suggests that the process and material characteristics of the silicon carbide should be considered in order to reinforcing against the single event effect of SiC power devices.展开更多
The epidemiological effects of native and mutated YMDD motif in the HBV genome under the selective pressure of lamivudine were investigated. YMDD wild and mutation motif in HBV genome were detected by flow through rev...The epidemiological effects of native and mutated YMDD motif in the HBV genome under the selective pressure of lamivudine were investigated. YMDD wild and mutation motif in HBV genome were detected by flow through reverse dot blots （PT-RDB） with KaiPuTM DNA HybriMax Rapid Hybridization Machine based on the principle of ＂Flow-through hybridization＂ and by the traditional Reverse Dot Blot assay. Sera from 1 021 suspected lamivudine-resistant chronic HBV carriers after more than 8 months of lamivudine therapy and the corresponding archived sera were collected and assayed. We found 35.94% were single type infections with 8.03% YMDD, 7.93% YIDD and 19.98% YVDD. It was also found that 64.06% were mixed infections including 1.96% YMDD and YIDD, 51.62% YMDD and YVDD, 1.96% YIDD and YVDD, 8.52% YMDD, YIDD and YVDD. The levels of infections containing YVDD motif reached 82.08%. The pretreatment infectious status were： YMDD single infection was 36.93%; YIDD single infection was 6.07%; YVDD single infection was 17.04%; YMDD and YIDD mixed infection was 0.97%; YMDD and YVDD mixed infection was 33.99%; YIDD and YVDD mixed infection was 0.98%; YMDD, YIDD and YVDD mixed infection was 4.02%. Infections containing YVDD motif were only 56.03%. The 34.32% mutation rate of YMDD motif to YVDD was significantly higher than the 10.97% of YMDD to YIDD （U=10.98, P〈0.05）, as estimated by Mann-Whitney U-test for non-parametric data. HBV containing YVDD motif might have an evolutionary ascendancy and become the dominant type under the selective pressure of lamivudine.展开更多
The aim of this study is to explore the genomic molecular organization and genogroup of human nomvirus from infected infants in Guangzhou of China. Primers were designed according to the genomic sequence of norovims i...The aim of this study is to explore the genomic molecular organization and genogroup of human nomvirus from infected infants in Guangzhou of China. Primers were designed according to the genomic sequence of norovims in the GenBank, and the nomvirus genome was amplified by RT-PCR. The PCR- products were cloned into T vector and sequenced, and the genomic nucleotide sequences were analyzed with the programs CLUSTAL W/X, DNASTAR and RAT （Recombination Analysis Tool）. The NVgz01 strain genome is 7558 bp in length and encodes three open reading frames （GenBank accession No. is DQ369797）. The genomic sequences of NVgz01 were compared with those of nomvirus in GenBank, which revealed that the homology with genogroup Ⅱ ranges between 76%-90%, and genogroup Ⅰ between 43%-44%. The ORF1 region shared 94% and 88% identity with Mc37 and Famiington strains, respectively; the capsid region （ORF2） shared 65% and 94% identity with Mc37 and Farmington strains, respectively. Phylogenetic trees were reconstructed by the neighbor-joining method. Comparative complete sequence analysis of the NVgz01 with reported human norovirus genomic sequences revealed that this isolate belongs to genogroup Ⅱ . The ORF1 and ORF2 regions shared different identity with Mc37 and Fannington strains, suggesting NVgz01 could be a recombinant virus.展开更多
To analyze the genomic molecular structure and genotype of human astrovirus isolated from infant in Guangzhou of China, the primers were designed based on the genomic sequence of astrovirus from the C, enBank and the ...To analyze the genomic molecular structure and genotype of human astrovirus isolated from infant in Guangzhou of China, the primers were designed based on the genomic sequence of astrovirus from the C, enBank and the target sequence were amplified by RT-PCR. Then the PCR-products were cloned to T vector and sequenced. The genomic nucleotide sequences were analyzed by the programs CLUSTAL W and DNASTAR. It was found that the full genomic length of HASTVgz01 strain was 6721 bp and the ORFs were 6558 bp. The 5＇ and 3＇UTR were 82 and 81 nucleotides. The genome included 3 open reading frames （ORFs） ： ORFla, ORFlb and ORF2. The 5＇-terminal ORFla started at nueleotide 83 and extended to nucleotide 2845. ORFlb （nt 2785 to nt 4332） overlaped ORFla by 61 nueleotides. The 3＇-terminal ORF2 began at nucleotide 4325 and terminated at nucleotide 6640. ORF2 had 2316 nucleotides. Compared with other astrovirus sequences in GenBank, the homology of the amino acid sequence of ORF2 of HASTVgz01 strain with that of serotype 4 was 93%. Homology with other serotypes ranged from 61% to 70%. The complete nucleotide sequence of astrovirus HASTVgz01 strain isolated from Guangzhou in China was 6721 bp in length, GenBank accession NO. DQ344027. Comparing the ORF2 of astrovirus HASTVgz01 with the known sequences of types 1-8 the highest homology was serotype 4 （93%）. Comparative sequence analysis of the HASTVgz01 ORF2 with the reported human astrovirus sequences revealed that the isolated astrovirus belongs to genotype （serotype） 4.展开更多
A dynamic triaxial instrument was used to study the effects of different concentrations of sodium chloride and stress amplitudes on the dynamic properties of an expansive soil under cyclic loading.In particular,four p...A dynamic triaxial instrument was used to study the effects of different concentrations of sodium chloride and stress amplitudes on the dynamic properties of an expansive soil under cyclic loading.In particular,four parameters were considered in such a parametric investigation,namely,hysteresis curve morphology characteristic non-closure degreeεp,the ratio of the short and long axisα,the slope of the long axis k and the enclosed area S.The results show that with an increase in the sodium chloride concentration,the soil particle double electric layer becomes thinner,the distance between soil particles decreases,and the whole sample becomes denser.Theεp-N,α-N and S–N relation curves all show a decreasing trend.The ratio of plastic deformation to total deformation grows with increasing the dynamic stress amplitude,and the curves show an upwards trend.The k-N relationship curve displays an increasing trend with the concentration and a general downwards trend as the dynamic stress amplitude is made higher.This also indicates that sodium chloride solutions can improve the engineering properties of expansive soil to a certain extent.With an increase in the vibration times N,the shape of the hysteretic curve becomes narrower,and the whole soil exhibits a cyclic strain hardening.With the help of an exponential function,a model is introduced to predict the relationship between the concentration and the hysteretic curve.展开更多
Jet precession has previously been proposed to explain the apparently repeating features in the light curves of a few gamma-ray bursts(GRBs).In this paper,we further apply the precession model to a bright GRB 220408B ...Jet precession has previously been proposed to explain the apparently repeating features in the light curves of a few gamma-ray bursts(GRBs).In this paper,we further apply the precession model to a bright GRB 220408B by examining both its temporal and spectral consistency with the predictions of the model.As one of the recently confirmed GRBs observed by our GRID CubeSat mission,GRB 220408B is noteworthy as it exhibits three apparently similar emission episodes.Furthermore,the similarities are reinforced by their strong temporal correlations and similar features in terms of spectral evolution and spectral lags.Our analysis demonstrates that these features can be well explained by the modulated emission of a Fast-Rise-Exponential-Decay(FRED)shape light curve intrinsically produced by a precessing jet with a precession period of 18.4_(-0.2)~(+0.2)s,a nutation period of11.1_(-0.2)~(+0.2)s and viewed off-axis.This study provides a straightforward explanation for the complex yet similar multiepisode GRB light curves.展开更多
BACKGROUND Allergic bronchopulmonary aspergillosis(ABPA)is an immune-related pulmonary disease caused by sensitization of airway by Aspergillus fumigatus.The disease manifests as bronchial asthma and recurring pulmona...BACKGROUND Allergic bronchopulmonary aspergillosis(ABPA)is an immune-related pulmonary disease caused by sensitization of airway by Aspergillus fumigatus.The disease manifests as bronchial asthma and recurring pulmonary shadows,which may be associated with bronchiectasis.The diagnosis of ABPA mainly depends on serological,immunological,and imaging findings.Pathological examination is not necessary but may be required in atypical cases to exclude pulmonary tuberculosis,tumor,and other diseases through lung biopsy.CASE SUMMARY An 18-year-old man presented with recurrent wheezing,cough,and peripheral blood eosinophilia.Chest computed tomography showed pulmonary infiltration.There was a significant increase in eosinophils in bronchoalveolar lavage fluid.There was no history of residing in a parasite-endemic area or any evidence of parasitic infection.Pathologic examination of bronchoalveolar lavage fluid excluded fungal and mycobacterial infections.The patient was receiving medication for comorbid diseases,but there was no temporal correlation between medication use and clinical manifestations,which excluded drug-induced etiology.Histopathological examination of lung biopsy specimen showed no signs of eosinophilic granulomatosis with polyangiitis,IgG4-related diseases,or tumors.The diagnosis of ABPA was considered based on the history of asthma and the significant increase in serum Aspergillus fumigatus-specific immunoglobulin(Ig)E.Eosinophil-related diseases were excluded through pathological biopsy,which showed typical pathological manifestations of ABPA.CONCLUSION The possibility of ABPA should be considered in patients with poorly controlled asthma,especially those with eosinophilia,lung infiltration shadows,or bronchiectasis.Screening for serum IgE,Aspergillus fumigatus-specific IgE and IgG,and alveolar lavage can help avoid misdiagnosis.展开更多
Accumulating studies have proved that perinatal exposure to environmental dose causes long-term potentiation in anxiety/depression-related behaviors in rats. Hyperactivity of the hypothalamic-pituitary-adrenal （HPA）...Accumulating studies have proved that perinatal exposure to environmental dose causes long-term potentiation in anxiety/depression-related behaviors in rats. Hyperactivity of the hypothalamic-pituitary-adrenal （HPA） axis is one of the most consistent biological findings in anxiety- and depression-related disorders. The HPA axis is reported to be susceptible to developmental reprogramming. The present study focused on HPA reactivity in postnatal day （PND） 80 male rats exposed perinatally to environmental-dose BPA. When female breeders were orally administered 2 μg/（kg.day） BPA from gestation day 10 to lactation day 7, their offspring （PND 80 BPA-exposed rats） showed obvious anxiety/depression-like behaviors. Notably, significant increase in serum corticosterone and adrenocorticotropin, and corticotropin-releasing hormone mRNA were detected in BPA-exposed rats before or after the mild stressor. Additionally, the level of glucocorticoid receptor mRNA in the hippocampus, but not the hypothalamus, was decreased in BPA-exposed rats. The levels of hippocampal mineralocorticoid receptor mRNA, neuronal nitric oxide synthase and phosphorylated cAMP response element binding protein were increased in BPA-exposed rats. In addition, the testosterone level was in BPA-exposed rats. The results indicate that reprogramming-induced hyperactivity of the HPA axis is an important link between perinatal BPA exposure and persistent potentiation in anxiety and depression.展开更多
AIM To construct the recombinant of HDVcDNA and HBV-specific ribozyme gene byrecombinant PCR in order to use HDV as atransporting vector carrying HBV-specificribozyme into liver cells for inhibiting thereplication of ...AIM To construct the recombinant of HDVcDNA and HBV-specific ribozyme gene byrecombinant PCR in order to use HDV as atransporting vector carrying HBV-specificribozyme into liver cells for inhibiting thereplication of HBV.METHODS We separately cloned the ribozyme（RZ）gene and recombinant DVRZ（comprisingHDV cDNA and HBV-specific ribozyme gene）intothe downstream of T7 promoter of pTAdv-Tvector and studied the in vitro cleavage activityof their transcripts（rRZ,rDVRZ）on target RNA（rBVCF）from in vitro transcription of HBV Cgene fragment（BVCF）.RESULTS Both the simple（rRZ）and therecombinant ribozyme rDVRZ could efficientlycatalyze the cleavage of target RNA（rBVCF）under different temperatures（37℃,42℃ and55℃）and Mg<sup>2+</sup>concentrations（10 mmol/L,15 mmol/L and 20 mmol/L）and their catalyticactivity tended to increase as the temperaturewas rising.But the activity of rRZ was evidentlyhigher than that of rDVRZ.CONCLUSION The recombinant of HDV cDNAand ribozyme gene had the potential of beingfurther explored and used in gene therapy of HBVinfection.展开更多
Multiplex RT-PCR assays have been widely used tools for detection and differentiation of a panel of respiratory viral pathogens. In this study, we evaluated the Qiagen ResPlex lI V2.0 kit and explored factors influenc...Multiplex RT-PCR assays have been widely used tools for detection and differentiation of a panel of respiratory viral pathogens. In this study, we evaluated the Qiagen ResPlex lI V2.0 kit and explored factors influencing its sensitivity. Nasopharyngeal swab （NPS） specimens were prospectively collected from pediatric inpatients with lower respiratory tract infections at the time of admission in the Shenzhen Children＇s Hospital from May 2009 to April 2010. Total nucleic acids were extracted using the EZ1 system （Qiagen, Germany） and 17 respiratory viruses and genotypes including influenza A virus （FluA）, FluB, parainfluenza virus 1 （PIV1）, PIV2, PIV3, PIV4, respiratory syncytial virus （RSV）, human metapneumovirus （hMPV）, rhinoviruses （RhV）, enteroviruses （EnV）, human bocaviruses （hBoV）, adenoviruses （AdV）, four coronaviruses （229E, OC43, NL63 and HKU1）, and FluA 2009 pandemic H1NI（H1NI-p） were detected and identified by the ResPlex II kit. In parallel, 16 real-time TaqMan quantitative RT-PCR assays were used to quantitatively detect each virus except for RhV. Influenza and parainfluenza viral cultures were also performed. Among the total 438 NPS specimens collected during the study period, one or more viral pathogens were detected in 274 （62.6%） and 201（45.9%） specimens by monoplex TaqMan RT-PCR and multiplex ResPlex, respectively. When results from monoplex PCR or cell culture were used as the reference standard, the multiplex PCR possessed specificities of 92.9-100.0%. The sensitivity of multiplex PCR for PIV3, hMPV, PIV1 and BoV were 73.1%, 70%, 66.7% and 55.6%, respectively, while low sensitivities （11.1%-40.0%） were observed for FluA, EnV, OC43, RSV and H1N1. Among the seven viruses/genotypes detected with higher frequencies, multiplex PCR sensitivities were correlated significantly with viral loads determined by the TaqMan RT-PCR in FluA, H 1N 1-p and RSV （p=0.011-0.000） The Qiagen ResPlex II multiplex RT-PCR kit possesses excellent specificity for simultaneous detection of 17 viral pathogens in NPS specimens in pediatric inpatients at the time of admission. The sensitivity of multiplex RT-PCR was influenced by viral loads, specimen process methods, primer and probe design and amplification condition.展开更多
Identifying a superior soybean variety with high defoliator resistance is important to avoid yield loss. Cotton bollworm(Helicoverpa armigera Hübner) is one of the major defoliators of soybean(Glycine max [L.] Me...Identifying a superior soybean variety with high defoliator resistance is important to avoid yield loss. Cotton bollworm(Helicoverpa armigera Hübner) is one of the major defoliators of soybean(Glycine max [L.] Merr.) worldwide. In this study, we evaluated the effect of H. armigera larvae on ED059, a wild soybean(Glycine soja Sieb. et Zucc.), and three cultivated soybean varieties: Tianlong 2, PI 535807, and PI 533604, in choice and no-choice assays. The percentage of ED059 leaflets consumed by H. armigera was lower than that of the three cultivated soybeans. Larvae that fed on ED059 exhibited low weight gain and high mortality rate.Waldbauer nutritional indices suggested that ED059 reduced the growth, consumption, and frass production of H. armigera larvae. Larvae that fed on ED059 showed lower efficiency of conversion of ingested and of digested food than those that fed on Tianlong 2 and PI 533604.However, they showed statistically similar consumption index and approximate digestibility compared with those fed on the three cultivated soybeans. Quantitative real-time PCR analysis revealed that 24 h after insect attack, ED059 had higher transcript levels of Kunitz trypsin inhibitor 3, Cysteine proteinase inhibitor 2, and Nerolidol synthase 1 but a lower transcript level of Pathogenesis-related protein 1 than Tianlong 2. The gene expression results were consistent with the presence of higher levels of jasmonic acid(JA) and transcript levels of the JA biosynthesis enzyme allene oxide cyclase 3 in ED059 than in Tianlong 2. Our findings indicate that ED059 is a superior soybean line with strong insect resistance that may be mediated via the JA pathway.展开更多
Apiaceae is a major family from Apiales and includes many important vegetable and medicinal crops.Heat shock transcription factors(Hsf)play important roles in heat tolerance during plant development.Here,we conducted ...Apiaceae is a major family from Apiales and includes many important vegetable and medicinal crops.Heat shock transcription factors(Hsf)play important roles in heat tolerance during plant development.Here,we conducted systematic analyses of the Hsf gene family in three Apiaceae species,including 17 Apium graveolens(celery),32 Coriandrum sativum(coriander),and 14 Daucus carota(carrot).A total of 73 Hsf genes were identified in three representative species,including Arabidopsis thaliana,Vitis vinifera,and Lactuca sativa.Whole-genome duplication played important roles in the Hsf gene family’s expansion within Apiaceae.Interestingly,we found that coriander had more Hsf genes than celery and carrot due to greater expansion and fewer losses.Twenty-seven branches of the phylogenetic tree underwent considerable positive selection in these Apiaceae species.We also explored the expression patterns of Hsf genes in three plant organs.Collectively,this study will serve as a rich gene resource for exploring the molecular mechanisms of heat tolerance.Additionally,this is the first study to report on the Hsf gene family in Apiaceae;thus,our research will provide guidance for future comparative and functional genomic studies on the Hsf gene family and others in Apiaceae.展开更多
文摘A comprehensive investigation was conducted to explore the degradation mechanism of leakage current in SiC junction barrier Schottky(JBS)diodes under heavy ion irradiation.We propose and verify that the generation of stacking faults(SFs)induced by the recombination of massive electron-hole pairs during irradiation is the cause of reverse leakage current degradation based on experiments results.The irradiation experiment was carried out based on Ta ions with high linear energy transfer(LET)of 90.5 MeV/(mg/cm^(2)).It is observed that the leakage current of the diode undergoes the permanent increase during irradiation when biased at 20%of the rated reverse voltage.Micro-PL spectroscopy and PL micro-imaging were utilized to detect the presence of SFs in the irradiated SiC JBS diodes.We combined the degraded performance of irradiated samples with SFs introduced by heavy ion irradiation.Finally,three-dimensional(3D)TCAD simulation was employed to evaluate the excessive electron-hole pairs(EHPs)concentration excited by heavy ion irradiation.It was observed that the excessive hole concentration under irradiation exceeded significantly the threshold hole concentration necessary for the expansion of SFs in the substrate.The proposed mechanism suggests that the process and material characteristics of the silicon carbide should be considered in order to reinforcing against the single event effect of SiC power devices.
基金National High Technology Research and Development Pro-gram of China(863 Program)Grant No. 2002AA-215018 from the Ministry of Science and Technology
文摘The epidemiological effects of native and mutated YMDD motif in the HBV genome under the selective pressure of lamivudine were investigated. YMDD wild and mutation motif in HBV genome were detected by flow through reverse dot blots （PT-RDB） with KaiPuTM DNA HybriMax Rapid Hybridization Machine based on the principle of ＂Flow-through hybridization＂ and by the traditional Reverse Dot Blot assay. Sera from 1 021 suspected lamivudine-resistant chronic HBV carriers after more than 8 months of lamivudine therapy and the corresponding archived sera were collected and assayed. We found 35.94% were single type infections with 8.03% YMDD, 7.93% YIDD and 19.98% YVDD. It was also found that 64.06% were mixed infections including 1.96% YMDD and YIDD, 51.62% YMDD and YVDD, 1.96% YIDD and YVDD, 8.52% YMDD, YIDD and YVDD. The levels of infections containing YVDD motif reached 82.08%. The pretreatment infectious status were： YMDD single infection was 36.93%; YIDD single infection was 6.07%; YVDD single infection was 17.04%; YMDD and YIDD mixed infection was 0.97%; YMDD and YVDD mixed infection was 33.99%; YIDD and YVDD mixed infection was 0.98%; YMDD, YIDD and YVDD mixed infection was 4.02%. Infections containing YVDD motif were only 56.03%. The 34.32% mutation rate of YMDD motif to YVDD was significantly higher than the 10.97% of YMDD to YIDD （U=10.98, P〈0.05）, as estimated by Mann-Whitney U-test for non-parametric data. HBV containing YVDD motif might have an evolutionary ascendancy and become the dominant type under the selective pressure of lamivudine.
文摘The aim of this study is to explore the genomic molecular organization and genogroup of human nomvirus from infected infants in Guangzhou of China. Primers were designed according to the genomic sequence of norovims in the GenBank, and the nomvirus genome was amplified by RT-PCR. The PCR- products were cloned into T vector and sequenced, and the genomic nucleotide sequences were analyzed with the programs CLUSTAL W/X, DNASTAR and RAT （Recombination Analysis Tool）. The NVgz01 strain genome is 7558 bp in length and encodes three open reading frames （GenBank accession No. is DQ369797）. The genomic sequences of NVgz01 were compared with those of nomvirus in GenBank, which revealed that the homology with genogroup Ⅱ ranges between 76%-90%, and genogroup Ⅰ between 43%-44%. The ORF1 region shared 94% and 88% identity with Mc37 and Famiington strains, respectively; the capsid region （ORF2） shared 65% and 94% identity with Mc37 and Farmington strains, respectively. Phylogenetic trees were reconstructed by the neighbor-joining method. Comparative complete sequence analysis of the NVgz01 with reported human norovirus genomic sequences revealed that this isolate belongs to genogroup Ⅱ . The ORF1 and ORF2 regions shared different identity with Mc37 and Fannington strains, suggesting NVgz01 could be a recombinant virus.
文摘To analyze the genomic molecular structure and genotype of human astrovirus isolated from infant in Guangzhou of China, the primers were designed based on the genomic sequence of astrovirus from the C, enBank and the target sequence were amplified by RT-PCR. Then the PCR-products were cloned to T vector and sequenced. The genomic nucleotide sequences were analyzed by the programs CLUSTAL W and DNASTAR. It was found that the full genomic length of HASTVgz01 strain was 6721 bp and the ORFs were 6558 bp. The 5＇ and 3＇UTR were 82 and 81 nucleotides. The genome included 3 open reading frames （ORFs） ： ORFla, ORFlb and ORF2. The 5＇-terminal ORFla started at nueleotide 83 and extended to nucleotide 2845. ORFlb （nt 2785 to nt 4332） overlaped ORFla by 61 nueleotides. The 3＇-terminal ORF2 began at nucleotide 4325 and terminated at nucleotide 6640. ORF2 had 2316 nucleotides. Compared with other astrovirus sequences in GenBank, the homology of the amino acid sequence of ORF2 of HASTVgz01 strain with that of serotype 4 was 93%. Homology with other serotypes ranged from 61% to 70%. The complete nucleotide sequence of astrovirus HASTVgz01 strain isolated from Guangzhou in China was 6721 bp in length, GenBank accession NO. DQ344027. Comparing the ORF2 of astrovirus HASTVgz01 with the known sequences of types 1-8 the highest homology was serotype 4 （93%）. Comparative sequence analysis of the HASTVgz01 ORF2 with the reported human astrovirus sequences revealed that the isolated astrovirus belongs to genotype （serotype） 4.
文摘A dynamic triaxial instrument was used to study the effects of different concentrations of sodium chloride and stress amplitudes on the dynamic properties of an expansive soil under cyclic loading.In particular,four parameters were considered in such a parametric investigation,namely,hysteresis curve morphology characteristic non-closure degreeεp,the ratio of the short and long axisα,the slope of the long axis k and the enclosed area S.The results show that with an increase in the sodium chloride concentration,the soil particle double electric layer becomes thinner,the distance between soil particles decreases,and the whole sample becomes denser.Theεp-N,α-N and S–N relation curves all show a decreasing trend.The ratio of plastic deformation to total deformation grows with increasing the dynamic stress amplitude,and the curves show an upwards trend.The k-N relationship curve displays an increasing trend with the concentration and a general downwards trend as the dynamic stress amplitude is made higher.This also indicates that sodium chloride solutions can improve the engineering properties of expansive soil to a certain extent.With an increase in the vibration times N,the shape of the hysteretic curve becomes narrower,and the whole soil exhibits a cyclic strain hardening.With the help of an exponential function,a model is introduced to predict the relationship between the concentration and the hysteretic curve.
基金support by the National Key Research and Development Programs of China(2022YFF0711404,2022SKA0130102)the National SKA Program of China(2022SKA0130100)+4 种基金the National Natural Science Foundation of China(grant Nos.11833003,U2038105,U1831135,12121003)the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-B11the Fundamental Research Funds for the Central Universitiesthe Program for Innovative Talents and Entrepreneur in Jiangsusupported by the National Postdoctoral Program for Innovative Talents(grant No.BX20200164)。
文摘Jet precession has previously been proposed to explain the apparently repeating features in the light curves of a few gamma-ray bursts(GRBs).In this paper,we further apply the precession model to a bright GRB 220408B by examining both its temporal and spectral consistency with the predictions of the model.As one of the recently confirmed GRBs observed by our GRID CubeSat mission,GRB 220408B is noteworthy as it exhibits three apparently similar emission episodes.Furthermore,the similarities are reinforced by their strong temporal correlations and similar features in terms of spectral evolution and spectral lags.Our analysis demonstrates that these features can be well explained by the modulated emission of a Fast-Rise-Exponential-Decay(FRED)shape light curve intrinsically produced by a precessing jet with a precession period of 18.4_(-0.2)~(+0.2)s,a nutation period of11.1_(-0.2)~(+0.2)s and viewed off-axis.This study provides a straightforward explanation for the complex yet similar multiepisode GRB light curves.
基金Supported by the National Natural Science Foundation of China,No.81900641the Research Funding of Peking University,No.BMU2021MX020,No.BMU2022MX008.
文摘BACKGROUND Allergic bronchopulmonary aspergillosis(ABPA)is an immune-related pulmonary disease caused by sensitization of airway by Aspergillus fumigatus.The disease manifests as bronchial asthma and recurring pulmonary shadows,which may be associated with bronchiectasis.The diagnosis of ABPA mainly depends on serological,immunological,and imaging findings.Pathological examination is not necessary but may be required in atypical cases to exclude pulmonary tuberculosis,tumor,and other diseases through lung biopsy.CASE SUMMARY An 18-year-old man presented with recurrent wheezing,cough,and peripheral blood eosinophilia.Chest computed tomography showed pulmonary infiltration.There was a significant increase in eosinophils in bronchoalveolar lavage fluid.There was no history of residing in a parasite-endemic area or any evidence of parasitic infection.Pathologic examination of bronchoalveolar lavage fluid excluded fungal and mycobacterial infections.The patient was receiving medication for comorbid diseases,but there was no temporal correlation between medication use and clinical manifestations,which excluded drug-induced etiology.Histopathological examination of lung biopsy specimen showed no signs of eosinophilic granulomatosis with polyangiitis,IgG4-related diseases,or tumors.The diagnosis of ABPA was considered based on the history of asthma and the significant increase in serum Aspergillus fumigatus-specific immunoglobulin(Ig)E.Eosinophil-related diseases were excluded through pathological biopsy,which showed typical pathological manifestations of ABPA.CONCLUSION The possibility of ABPA should be considered in patients with poorly controlled asthma,especially those with eosinophilia,lung infiltration shadows,or bronchiectasis.Screening for serum IgE,Aspergillus fumigatus-specific IgE and IgG,and alveolar lavage can help avoid misdiagnosis.
基金supported by China Postdoctoral Science Foundation(2013M540456)Jiangsu Planned Projects for Postdoctoral Research Funds(1301065B)+3 种基金Grants for 973(2014CB943303)NSFC(810710273117144081000482)
文摘Accumulating studies have proved that perinatal exposure to environmental dose causes long-term potentiation in anxiety/depression-related behaviors in rats. Hyperactivity of the hypothalamic-pituitary-adrenal （HPA） axis is one of the most consistent biological findings in anxiety- and depression-related disorders. The HPA axis is reported to be susceptible to developmental reprogramming. The present study focused on HPA reactivity in postnatal day （PND） 80 male rats exposed perinatally to environmental-dose BPA. When female breeders were orally administered 2 μg/（kg.day） BPA from gestation day 10 to lactation day 7, their offspring （PND 80 BPA-exposed rats） showed obvious anxiety/depression-like behaviors. Notably, significant increase in serum corticosterone and adrenocorticotropin, and corticotropin-releasing hormone mRNA were detected in BPA-exposed rats before or after the mild stressor. Additionally, the level of glucocorticoid receptor mRNA in the hippocampus, but not the hypothalamus, was decreased in BPA-exposed rats. The levels of hippocampal mineralocorticoid receptor mRNA, neuronal nitric oxide synthase and phosphorylated cAMP response element binding protein were increased in BPA-exposed rats. In addition, the testosterone level was in BPA-exposed rats. The results indicate that reprogramming-induced hyperactivity of the HPA axis is an important link between perinatal BPA exposure and persistent potentiation in anxiety and depression.
基金Natural Science Foundation of Guangdong Province,No.940311.
文摘AIM To construct the recombinant of HDVcDNA and HBV-specific ribozyme gene byrecombinant PCR in order to use HDV as atransporting vector carrying HBV-specificribozyme into liver cells for inhibiting thereplication of HBV.METHODS We separately cloned the ribozyme（RZ）gene and recombinant DVRZ（comprisingHDV cDNA and HBV-specific ribozyme gene）intothe downstream of T7 promoter of pTAdv-Tvector and studied the in vitro cleavage activityof their transcripts（rRZ,rDVRZ）on target RNA（rBVCF）from in vitro transcription of HBV Cgene fragment（BVCF）.RESULTS Both the simple（rRZ）and therecombinant ribozyme rDVRZ could efficientlycatalyze the cleavage of target RNA（rBVCF）under different temperatures（37℃,42℃ and55℃）and Mg<sup>2+</sup>concentrations（10 mmol/L,15 mmol/L and 20 mmol/L）and their catalyticactivity tended to increase as the temperaturewas rising.But the activity of rRZ was evidentlyhigher than that of rDVRZ.CONCLUSION The recombinant of HDV cDNAand ribozyme gene had the potential of beingfurther explored and used in gene therapy of HBVinfection.
基金supported in part by Grant Name awarded to the State Key Lab of Respiratory Diseases,Guangzhou Medical College (2007DA780154F0910)
文摘Multiplex RT-PCR assays have been widely used tools for detection and differentiation of a panel of respiratory viral pathogens. In this study, we evaluated the Qiagen ResPlex lI V2.0 kit and explored factors influencing its sensitivity. Nasopharyngeal swab （NPS） specimens were prospectively collected from pediatric inpatients with lower respiratory tract infections at the time of admission in the Shenzhen Children＇s Hospital from May 2009 to April 2010. Total nucleic acids were extracted using the EZ1 system （Qiagen, Germany） and 17 respiratory viruses and genotypes including influenza A virus （FluA）, FluB, parainfluenza virus 1 （PIV1）, PIV2, PIV3, PIV4, respiratory syncytial virus （RSV）, human metapneumovirus （hMPV）, rhinoviruses （RhV）, enteroviruses （EnV）, human bocaviruses （hBoV）, adenoviruses （AdV）, four coronaviruses （229E, OC43, NL63 and HKU1）, and FluA 2009 pandemic H1NI（H1NI-p） were detected and identified by the ResPlex II kit. In parallel, 16 real-time TaqMan quantitative RT-PCR assays were used to quantitatively detect each virus except for RhV. Influenza and parainfluenza viral cultures were also performed. Among the total 438 NPS specimens collected during the study period, one or more viral pathogens were detected in 274 （62.6%） and 201（45.9%） specimens by monoplex TaqMan RT-PCR and multiplex ResPlex, respectively. When results from monoplex PCR or cell culture were used as the reference standard, the multiplex PCR possessed specificities of 92.9-100.0%. The sensitivity of multiplex PCR for PIV3, hMPV, PIV1 and BoV were 73.1%, 70%, 66.7% and 55.6%, respectively, while low sensitivities （11.1%-40.0%） were observed for FluA, EnV, OC43, RSV and H1N1. Among the seven viruses/genotypes detected with higher frequencies, multiplex PCR sensitivities were correlated significantly with viral loads determined by the TaqMan RT-PCR in FluA, H 1N 1-p and RSV （p=0.011-0.000） The Qiagen ResPlex II multiplex RT-PCR kit possesses excellent specificity for simultaneous detection of 17 viral pathogens in NPS specimens in pediatric inpatients at the time of admission. The sensitivity of multiplex RT-PCR was influenced by viral loads, specimen process methods, primer and probe design and amplification condition.
基金funded by the China Agriculture Research System (CAAS-04-PS08)the National Transgenic Project of China (2014ZX08004-005)the Agricultural Science and Technology Innovation Program of China
文摘Identifying a superior soybean variety with high defoliator resistance is important to avoid yield loss. Cotton bollworm(Helicoverpa armigera Hübner) is one of the major defoliators of soybean(Glycine max [L.] Merr.) worldwide. In this study, we evaluated the effect of H. armigera larvae on ED059, a wild soybean(Glycine soja Sieb. et Zucc.), and three cultivated soybean varieties: Tianlong 2, PI 535807, and PI 533604, in choice and no-choice assays. The percentage of ED059 leaflets consumed by H. armigera was lower than that of the three cultivated soybeans. Larvae that fed on ED059 exhibited low weight gain and high mortality rate.Waldbauer nutritional indices suggested that ED059 reduced the growth, consumption, and frass production of H. armigera larvae. Larvae that fed on ED059 showed lower efficiency of conversion of ingested and of digested food than those that fed on Tianlong 2 and PI 533604.However, they showed statistically similar consumption index and approximate digestibility compared with those fed on the three cultivated soybeans. Quantitative real-time PCR analysis revealed that 24 h after insect attack, ED059 had higher transcript levels of Kunitz trypsin inhibitor 3, Cysteine proteinase inhibitor 2, and Nerolidol synthase 1 but a lower transcript level of Pathogenesis-related protein 1 than Tianlong 2. The gene expression results were consistent with the presence of higher levels of jasmonic acid(JA) and transcript levels of the JA biosynthesis enzyme allene oxide cyclase 3 in ED059 than in Tianlong 2. Our findings indicate that ED059 is a superior soybean line with strong insect resistance that may be mediated via the JA pathway.
基金supported by the National Natural Science Foundation of China(Grant No.31801856)Hebei Province Higher Education Youth Talents Program(Grant No.BJ2018016)+1 种基金the China Postdoctoral Science Foundation(Grant No.2020M673188)the innovation and entrepreneurship training program for college students of North China University of Science and Technology(Grant No.X2019256).
文摘Apiaceae is a major family from Apiales and includes many important vegetable and medicinal crops.Heat shock transcription factors(Hsf)play important roles in heat tolerance during plant development.Here,we conducted systematic analyses of the Hsf gene family in three Apiaceae species,including 17 Apium graveolens(celery),32 Coriandrum sativum(coriander),and 14 Daucus carota(carrot).A total of 73 Hsf genes were identified in three representative species,including Arabidopsis thaliana,Vitis vinifera,and Lactuca sativa.Whole-genome duplication played important roles in the Hsf gene family’s expansion within Apiaceae.Interestingly,we found that coriander had more Hsf genes than celery and carrot due to greater expansion and fewer losses.Twenty-seven branches of the phylogenetic tree underwent considerable positive selection in these Apiaceae species.We also explored the expression patterns of Hsf genes in three plant organs.Collectively,this study will serve as a rich gene resource for exploring the molecular mechanisms of heat tolerance.Additionally,this is the first study to report on the Hsf gene family in Apiaceae;thus,our research will provide guidance for future comparative and functional genomic studies on the Hsf gene family and others in Apiaceae.
