AIM: To investigate preoperative differential diagnoses made between intrahepatic biliary cystadenoma and intrahepatic biliary cystadenocarcinoma. METHODS: A retrospective analysis of patient data was performed, which...AIM: To investigate preoperative differential diagnoses made between intrahepatic biliary cystadenoma and intrahepatic biliary cystadenocarcinoma. METHODS: A retrospective analysis of patient data was performed, which included 21 cases of intrahepatic biliary cystadenoma and 25 cases of intrahepatic biliary cystadenocarcinoma diagnosed between April 2003 and April 2013 at the General Hospital of PLA. Potential patients were excluded whose diagnoses were not confirmed pathologically. Basic information (including patient age and gender), clinical manifestation, duration of symptoms, serum assay results (including tumor markers and the results of liver function tests), radiological features and pathological results were collected. All patients were followed up. RESULTS: Preoperative levels of cancer antigen 125 (12.51 +/- 9.31 vs 23.20 +/- 21.86, P < 0.05) and carbohydrate antigen 19-9 (22.56 +/- 26.30 vs 72.55 +/- 115.99, P < 0.05) were higher in the cystadenocarcinoma subgroup than in the cystadenoma subgroup. There were no statistically significant differences in age or gender between the two groups, or in pre- or post-operative levels of alanine aminotransferase, aspartate aminotransferase, total bilirubin (TBIL), and direct bilirubin (DBIL) between the two groups. However, eight of the 21 patients with cystadenoma and six of the 25 patients with cystadenocarcinoma had elevated levels of TBIL and DBIL. There were three cases in the cystadenoma subgroup and six cases in the cystadenocarcinoma subgroup with postoperative complications. CONCLUSION: Preoperative differential diagnosis relies on the integration of information, including clinical symptoms, laboratory findings and imaging results. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.展开更多
Fast Radio Bursts (FRBs) are intense radio flashes from the sky that are characterized by mil- lisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discove...Fast Radio Bursts (FRBs) are intense radio flashes from the sky that are characterized by mil- lisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discovered. Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be ~ 660 pc cm-3, supporting their being from a cosmological origin. Their energy released in the radio band spans about two orders of magnitude, with a mean value of ~ 10-39 erg. More interestingly, although the study of FRBs is still in a very early phase, the published collection of FRBs enables us to derive a useful intensity distribution function. For the 16 non-repeating FRBs detected by the Parkes telescope and the Green Bank Telescope, the intensity distribution can be described as dN/dFobs = (4.1± 1.3) × 103 F-obs1.1±0.2 sky-1 d-l, where Fobs is the observed radio obs fluence in units of Jy ms. Here the power-law index is significantly flatter than the expected value of 2.5 for standard candles distributed homogeneously in a flat Euclidean space. Based on this intensity distribution function, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) is predicted to be able to detect about five FRBs for every 1000 h of observation time.展开更多
γ-MnO2 nanorod-assembled hierarchical micro-spheres with abundant oxygen defects are synthesized by a simple thermal treatment approach as oxygen reduction electrocatalysts for Al(aluminum)-air batteries. The rich ox...γ-MnO2 nanorod-assembled hierarchical micro-spheres with abundant oxygen defects are synthesized by a simple thermal treatment approach as oxygen reduction electrocatalysts for Al(aluminum)-air batteries. The rich oxygen vacancies on the surface of γ-MnO2 are verified by morphology, structure,electron paramagnetic resonance(EPR) and X-ray photoelectron spectroscopy(XPS) results. The oxygen reduction reaction(ORR) electrocatalytic activity of γ-MnO2 is significantly improved by the incoming oxygen vacancies. The γ-MnO2 nanorod-assembled hierarchical micro-spheres calcined under 300 °C in Ar atmosphere show the best ORR performance. The primary Al-air batteries using γ-MnO2 catalysts as the cathode, which demonstrates excellent peal power density of 318 m W cm^(-2) when applying theγ-MnO2 catalysts with optimal amount of oxygen vacancies.展开更多
The reconstruction control of modular self-reconfigurable spacecraft (MSRS) is addressed using an adaptive sliding mode control (ASMC) scheme based on time-delay estimation (TDE) technology. In contrast to the ground,...The reconstruction control of modular self-reconfigurable spacecraft (MSRS) is addressed using an adaptive sliding mode control (ASMC) scheme based on time-delay estimation (TDE) technology. In contrast to the ground, the base of the MSRS is floating when assembled in orbit, resulting in a strong dynamic coupling effect. A TED-based ASMC technique with exponential reaching law is designed to achieve high-precision coordinated control between the spacecraft base and the robotic arm. TDE technology is used by the controller to compensate for coupling terms and uncertainties, while ASMC can augment and improve TDE’s robustness. To suppress TDE errors and eliminate chattering, a new adaptive law is created to modify gain parameters online, ensuring quick dynamic response and high tracking accuracy. The Lyapunov approach shows that the tracking errors are uniformly ultimately bounded (UUB). Finally, the on-orbit assembly process of MSRS is simulated to validate the efficacy of the proposed control scheme. The simulation results show that the proposed control method can accurately complete the target module’s on-orbit assembly, with minimal perturbations to the spacecraft’s attitude. Meanwhile, it has a high level of robustness and can effectively eliminate chattering.展开更多
The curvature of the γ-ray spectrum in blazars may reflect the intrinsic distribution of emitting electrons, which will further give some information on the possible acceleration and cooling processes in the emitting...The curvature of the γ-ray spectrum in blazars may reflect the intrinsic distribution of emitting electrons, which will further give some information on the possible acceleration and cooling processes in the emitting region. The γ-ray spectra of Fermi blazars are normally fitted either by a single power-law(PL) or a log-normal(call Logarithmic Parabola, LP) form. The possible reason for this difference is not clear. We statistically explore this issue based on the different observational properties of 1419 Fermi blazars in the 3 LAC Clean Sample. We find that the γ-ray flux(100 Me V–100 Ge V) and variability index follow bimodal distributions for PL and LP blazars, where the γ-ray flux and variability index show a positive correlation. However, the distributions of γ-ray luminosity and redshift follow a unimodal distribution. Our results suggest that the bimodal distribution of γ-ray fluxes for LP and PL blazars may not be intrinsic and all blazars may have an intrinsically curved γ-ray spectrum, and the PL spectrum is just caused by the fitting effect due to less photons.展开更多
Using 64 ms count data of long gamma-ray bursts (T90 〉 2.6 s), we analyze the quantity named relative spectral lag (RSL), T31/FWHM(1). We investigated in detail all the correlations between the RSL and other pa...Using 64 ms count data of long gamma-ray bursts (T90 〉 2.6 s), we analyze the quantity named relative spectral lag (RSL), T31/FWHM(1). We investigated in detail all the correlations between the RSL and other parameters for a sample of nine long bursts, using the general cross-correlation technique that includes the lag between two different energy bands. We conclude that the distribution of RSLs is normal and has a mean value of 0.1; that the RSLs are weakly correlated with the FWHM, the asymmetry, peak flux (Fp), peak energy (Ep) and spectral indexes (α and β), while they are uncorrelated with τ31, the hardness- ratio (HR31) and the peak time (tm). Our important discovery is that redshift (z) and peak luminosity (Lp) are strongly correlated with the RSL, which can be measured easily and directly, making the RSL a good redshift and peak luminosity indicator.展开更多
As a result of an error by the authors,in the paper,one of the authors’names,“Xu-Juan Li”,was misspelled.The correct spelling of the name should be“Xiu-Juan Li”.
The coronavirus disease 2019(COVID-19)pandemic has greatly damaged human society,but the origins and early transmission patterns of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)pathogen remain unclea...The coronavirus disease 2019(COVID-19)pandemic has greatly damaged human society,but the origins and early transmission patterns of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)pathogen remain unclear.Here,we reconstructed the transmission networks of SARS-CoV-2 during the first three and six months since its first report based on ancestor-offspring relationships using BANAL-52-referenced mutations.We explored the position(i.e.,root,middle,or tip)of early detected samples in the evolutionary tree of SARS-CoV-2.In total,6799 transmission chains and 1766 transmission networks were reconstructed,with chain lengths ranging from 1-9 nodes.The root node samples of the 1766 transmission networks were from 58 countries or regions and showed no common ancestor,indicating the occurrence of many independent or parallel transmissions of SARS-CoV-2 when first detected(i.e.,all samples were located at the tip position of the evolutionary tree).No root node sample was found in any sample(n=31,all from the Chinese mainland)collected in the first 15 days from 24 December 2019.Results using six-month data or RaTG13-referenced mutation data were similar.The reconstruction method was verified using a simulation approach.Our results suggest that SARS-CoV-2 may have already been spreading independently worldwide before the outbreak of COVID-19 in Wuhan,China.Thus,a comprehensive global survey of human and animal samples is essential to explore the origins of SARS-CoV-2 and its natural reservoirs and hosts.展开更多
A 135 mW single-frequency distributed Bragg reflector fiber laser at 1.95μm was obtained based on a Tm:YAG ceramic-derived all-glass fiber.The fiber laser achieved an optical signal-to-noise ratio of~77 d B.Moreover,...A 135 mW single-frequency distributed Bragg reflector fiber laser at 1.95μm was obtained based on a Tm:YAG ceramic-derived all-glass fiber.The fiber laser achieved an optical signal-to-noise ratio of~77 d B.Moreover,the threshold and linewidth of the single-frequency laser were measured to be 15.4 mW and 4.5 kHz,respectively.In addition,the measured relative intensity noise was less than-140 d B·Hz^(-1)at frequencies of over 10 MHz.The results show that the as-drawn Tm:YAG ceramic-derived all-glass fiber is highly promising for~2μm single-frequency fiber laser applications.展开更多
Using the generic hydrodynamic model of gamma-ray burst (GRB) after- glows, we calculate the radio afterglow light curves of low luminosity, high luminosity, failed and standard GRBs in different observational bands...Using the generic hydrodynamic model of gamma-ray burst (GRB) after- glows, we calculate the radio afterglow light curves of low luminosity, high luminosity, failed and standard GRBs in different observational bands of FAST's energy window. The GRBs are assumed to be located at different distances from us. Our results rank the detectability of GRBs in descending order as high luminosity, standard, failed and low luminosity GRBs. We predict that almost all types of radio afterglows except those of low luminosity GRBs could be observed by a large radio telescope as long as the domains of time and frequency are appropriate. It is important to note that FAST can detect relatively weak radio afterglows at a higher frequency of 2.5 GHz for very high redshift up to z = 15 or even more. Radio afterglows of low luminosity GRBs can only be detected after the completion of the second phase of FAST. FAST is expected to significantly expand the sample of GRB radio afterglows in the near future.展开更多
Thanks to more and more gamma-ray bursts with measured redshift and extended emission detected by the recent space telescopes,it is urgent and possible to check whether those previous energy correlations still satisfy...Thanks to more and more gamma-ray bursts with measured redshift and extended emission detected by the recent space telescopes,it is urgent and possible to check whether those previous energy correlations still satisfy the particular sample involving only the bursts accompanied by tail radiations.Using 20 long and 22 short bursts with extended emission,we find that the popular γ-ray energy correlations of the intrinsic peak energy versus the isotropic energy(Amati relation) and the intrinsic peak energy versus the peak luminosity(Yonetoku relation) do exist in both short and long bursts.However,it is much better if these gamma-ray bursts with extended emissions are reclassified into two subgroups of E-Ⅰ and E-Ⅱ that make the above energy correlations more tight.As proposed by Zhang et al.,the energy correlations can be utilized to distinguish these kinds of gamma-ray bursts in the plane of bolometric fluence versus peak energy as well.Interestingly,the peculiar short GRB 170817 A belongs to the E-Ⅰ group in the fluence versus peak energy plane,but it is an outlier of both the Amati and Yonetoku relations even though the off-axis effect has been corrected.Furthermore,we compare the radiation features between the extended emissions and the prompt gamma-rays in order to search for their possible connections.Taking into account all these factors,we conclude that gamma-ray bursts with extended emission are still required to model with dichotomic groups,namely E-Ⅰ and E-Ⅱ classes,which hint that they might have different origins.展开更多
Objective:To study the correlation of ERCC1 and GSTP1 expression in esophageal cancer tissue with platinum-based chemotherapy sensitivity as well as apoptosis and proliferation gene expression.Methods: Patients with a...Objective:To study the correlation of ERCC1 and GSTP1 expression in esophageal cancer tissue with platinum-based chemotherapy sensitivity as well as apoptosis and proliferation gene expression.Methods: Patients with advanced esophageal cancer who accepted PF chemotherapy in our hospital between May 2013 and October 2015 were selected, esophageal cancer tissue was collected before the chemotherapy, the patients were divided into chemotherapy sensitivity group and chemotherapy resistance group according to the effect of chemotherapy, and the expression levels of ERCC1, GSTP1 as well as apoptosis and proliferation genes in esophageal cancer tissue were detected.Results:Protein content and positive protein expression rate of ERCC1 and GSTP1 in esophageal cancer tissue of chemotherapy sensitivity group were significantly lower than those of chemotherapy resistance group, MBP1, DEC1 and PTEN protein content were significantly higher than those of chemotherapy resistance group, and PLCE1, CyclinD1 and PAR2 protein content were significantly lower than those of chemotherapy resistance group;MBP1, DEC1 and PTEN protein content in esophageal cancer tissue with positive ERCC1 and GSTP1 expression were significantly lower than those in esophageal cancer tissue with negative ERCC1 and GSTP1 expression while PLCE1, CyclinD1 and PAR2 protein content were significantly higher than those in esophageal cancer tissue with negative ERCC1 and GSTP1 expression.Conclusion:The highly expressed ERCC1 and GSTP1 in esophageal cancer tissue can decreased the cancer cell sensitivity to platinum-based chemotherapeutics, inhibit cell apoptosis and promote cell proliferation during platinum-based chemotherapy.展开更多
Since the first isolation of graphene by Geim and Novoselov in 2004,this two-dimensional(2D)material has attracted significant attention from the scientific and engineering communities.^(1)Due to its structure with a ...Since the first isolation of graphene by Geim and Novoselov in 2004,this two-dimensional(2D)material has attracted significant attention from the scientific and engineering communities.^(1)Due to its structure with a single layer of covalently bonded sp^(2)-hybridized carbon atoms,graphene has superior mechanical,electrical,optical,and thermal properties.^(2-4)Although mechanical exfoliation remains an ideal method for obtaining highquality graphene,its scalability is severely limited;thus,it is impractical for industrial applications.In pursuit of a method suitable for large-scale production,research has been performed using chemical vapor deposition(CVD)methods for synthesizing graphene on metal substrates.展开更多
Common wheat(Triticum aestivum,BBAADD)is a major staple food crop worldwide.The diploid progenitors of the A and D subgenomes have been unequivocally identified;that of B,however,remains ambiguous and controversial bu...Common wheat(Triticum aestivum,BBAADD)is a major staple food crop worldwide.The diploid progenitors of the A and D subgenomes have been unequivocally identified;that of B,however,remains ambiguous and controversial but is suspected to be related to species of Aegilops,section Sitopsis.Here,we report the assembly of chromosome-level genome sequences of all five Sitopsis species,namely Aegilops bicornis,Ae.longissima,Ae.searsii,Ae.sharonensis,and Ae.speltoides,as well as the partial assembly of the Amblyopyrum muticum(synonym Aegilops mutica)genome for phylogenetic analysis.Our results reveal that the donor of the common wheat B subgenome is a distinct,and most probably extinct,diploid species that diverged from an ancestral progenitor of the B lineage to which the still extant Ae.speltoides and Am.muticum belong.In addition,we identified interspecific genetic introgressions throughout the evolution of the Triticum/Aegilops species complex.The five Sitopsis species have various assembled genome sizes(4.11-5.89 Gb)with high proportions of repetitive sequences(85.99%-89.81%);nonetheless,they retain high collinearity with other genomes or subgenomes of species in the Triticum/Aegilops complex.Differences in genome size were primarily due to independent post-speciation amplification of transposons.We also identified a set of Sitopsis genes pertinent to important agronomic traits that can be harnessed for wheat breeding.These newly assembled genome resources provide a new roadmap for evolutionary and genetic studies of the Triticum/Aegilops complex,as well as for wheat improvement.展开更多
Background:Epithelial to mesenchymal transition (EMT) is strongly linked with tumor invasion and metastasis, which performs a vital role in carcinogenesis and cancer progression. Emerging evidence suggests that microR...Background:Epithelial to mesenchymal transition (EMT) is strongly linked with tumor invasion and metastasis, which performs a vital role in carcinogenesis and cancer progression. Emerging evidence suggests that microRNAs (miRNAs) expression are closely associated to EMT by regulating targeted genes. MiR542 has been found to be involved in the EMT program and bound up with various cancers. However, the functions of miR542 and its underlying mechanism in glioblastoma multiforme (GBM) remain largely unknown. In the current study, we investigated the effect of astrocyte elevated gene-1 ( AEG-1) on U251 cells aggressiveness, proliferation, apoptosis, and cell cycle. Methods:The screening of targeted miRNAs was performed, as well as the functional roles and mechanisms of miR542 were explored.Results:MiR542 was selected as the target because of the most significantly differential expression and this high level of expression negatively correlated with cell migration and proliferation, which suggested that miR542 could be a novel tumor suppressor. Moreover, we confirmed that AEG-1 was a direct targeted gene of miR542 by luciferase activity assay, reverse transcription-polymerase chain reaction, and immunoblotting analysis. Furthermore, miR542 suppressed the expression of AEG-1, which upgraded the level of E-cadherin and degraded Vimentin expression contributing to retraining EMT. Conclusion:The in vitro findings demonstrated that miR542 inhibited the migration and proliferation of U251 cells and suppressed EMT through targeting AEG-1, indicating that miR542 may be a potential anti-cancer target for GBM.展开更多
Dual-phase high-entropy alloys containing facecentered cubic(fcc) and body-centered cubic(bcc) phases achieve a combination of high strength and high ductility,which attract extensive attention.Compared with singlepha...Dual-phase high-entropy alloys containing facecentered cubic(fcc) and body-centered cubic(bcc) phases achieve a combination of high strength and high ductility,which attract extensive attention.Compared with singlephase high-entropy alloys,the dual-phase structure generates more complex deformation mechanisms such as structural transformation and interactions between grain boundaries and dislocations during deformation.In order to understand the structural transformation of the dual-phase high-entropy alloy during deformation and its effect on mechanical properties,Al_(0.5)CoCrNiFe high-entropy alloy was prepared and its deformation mechanism was investigated by molecular dynamics simulations combined with experiments.The results show that phase transformation occurred during deformation,and dislocation slip was the main deformation mechanism.In addition,there was significant dislocation pile-up at the interface between fcc and bcc phases after tensile deformation.Temperatures and strain rates significantly affected the mechanical properties and deformation behavior of high-entropy alloys.At low temperature and high strain rate,the dislocation density of the alloy increases after stretching,resulting in the enhancement of tensile strength.展开更多
Into the 21st century, remanufacturing engineering has been accepted by more and more people in China. Remanufacturing is an industrial maintenance technology for worn or waste electro-mechanical products using advanc...Into the 21st century, remanufacturing engineering has been accepted by more and more people in China. Remanufacturing is an industrial maintenance technology for worn or waste electro-mechanical products using advanced technology, which means the high-level stage for the maintenance and surface engineering. In this paper, a new automotive high velocity arc spraying system was introduced. And three kinds of advanced amorphous and nanocrystalline metastable coatings were developed, including Fe, Ni and Al-based amorphous and nanocrystalline composite coatings. Their research development and applications were introduced. And the development trends of high velocity arc spraying system and advanced metastable surface protective coating materials on the remanu- facturing engineering were indicated.展开更多
In this work,the effect of Re alloying on the phase composition,crystal structure,and mechanical properties of NbMoTaWRe_(x) (x=0,0.27,0.57,0.92,1.33) refractory high-entropy alloys (RHEAs) were systematically investi...In this work,the effect of Re alloying on the phase composition,crystal structure,and mechanical properties of NbMoTaWRe_(x) (x=0,0.27,0.57,0.92,1.33) refractory high-entropy alloys (RHEAs) were systematically investigated by combining the calculation of phase diagram(CALPHAD),first-principle calculations and experiment.The theoretical predictions showed good consistency with the experimental results.As the increase in Re content,the theoretical results showed that all considered alloys have a single body-centered cubic (bcc) structure and the lattice constant and ductility were decreased,while the elastic moduli and hardness were improved.To avoid extreme brittleness,a strategic suggestion was given for the design of Re-containing RHEAs in the future.展开更多
To the Editor: A 19-year-old man was admitted to the hospital presenting with “skin and sclera yellow staining for 18 years, accompanied by growth retardation.” The patient developed scleral yellowing at 4 months of...To the Editor: A 19-year-old man was admitted to the hospital presenting with “skin and sclera yellow staining for 18 years, accompanied by growth retardation.” The patient developed scleral yellowing at 4 months of age, at which time he was diagnosed as having Wilson's disease (WD) and received symptomatic treatment for liver protection. At 9 years of age the patient developed a pale nail bed, clubbing of the fingers and toes, and accompanying growth retardation. A spontaneous fracture of the right upper limb and left pubic bone occurred at 16 years of age. At 17 years of age the patient developed neuropsychiatric symptoms consisting of fatigue, personality changes, mental retardation, numbness, epileptic seizures, and constipation. He required daily glycerin to assist with defecation. At 5 months prior to admission, obvious sternal malformations and anterior sternal processes were present. Family history revealed that his parents were close relatives (cousin-sister relationship) and the patient's cousin died as a result of WD at age of 12 years. The patient's younger brother was 3 years old and also had a history of WD.展开更多
Introduction Psoriasis characterized by red scaly skin lesions clinically is a chronic inflammatory skin disease,and there are 0.53%-11.43% of the adults around the world suffered[1].The pathophysiological changes o...Introduction Psoriasis characterized by red scaly skin lesions clinically is a chronic inflammatory skin disease,and there are 0.53%-11.43% of the adults around the world suffered[1].The pathophysiological changes of psoriasis are characterized by proliferation accelerated in epidermal basal keratinocytes and infiltration of inflammatory cells from epidermis and dermis.Many studies have shown that the occurrence and development of psoriasis is closely related to genes,cell signaling pathways and proliferation.The relationships between peroxisome proliferator-activated receptor-γ(PPARγ) and TGF-β/Smad signaling pathway and psoriasis has been mostly studied in recent years[2].展开更多
文摘AIM: To investigate preoperative differential diagnoses made between intrahepatic biliary cystadenoma and intrahepatic biliary cystadenocarcinoma. METHODS: A retrospective analysis of patient data was performed, which included 21 cases of intrahepatic biliary cystadenoma and 25 cases of intrahepatic biliary cystadenocarcinoma diagnosed between April 2003 and April 2013 at the General Hospital of PLA. Potential patients were excluded whose diagnoses were not confirmed pathologically. Basic information (including patient age and gender), clinical manifestation, duration of symptoms, serum assay results (including tumor markers and the results of liver function tests), radiological features and pathological results were collected. All patients were followed up. RESULTS: Preoperative levels of cancer antigen 125 (12.51 +/- 9.31 vs 23.20 +/- 21.86, P < 0.05) and carbohydrate antigen 19-9 (22.56 +/- 26.30 vs 72.55 +/- 115.99, P < 0.05) were higher in the cystadenocarcinoma subgroup than in the cystadenoma subgroup. There were no statistically significant differences in age or gender between the two groups, or in pre- or post-operative levels of alanine aminotransferase, aspartate aminotransferase, total bilirubin (TBIL), and direct bilirubin (DBIL) between the two groups. However, eight of the 21 patients with cystadenoma and six of the 25 patients with cystadenocarcinoma had elevated levels of TBIL and DBIL. There were three cases in the cystadenoma subgroup and six cases in the cystadenocarcinoma subgroup with postoperative complications. CONCLUSION: Preoperative differential diagnosis relies on the integration of information, including clinical symptoms, laboratory findings and imaging results. (C) 2014 Baishideng Publishing Group Inc. All rights reserved.
基金supported by the National Basic Research Program of China(973 program,Grant Nos.2014CB845800 and 2012CB821802)the National Natural Science Foundation of China(Grant Nos.11473012,U1431126 and 11263002)+1 种基金the Strategic Priority Research Program(Grant Nos.XDB09010302 and XDB23000000)the support from the CAS Interdisciplinary Innovation Team and the CAS Key International Collaboration Program
文摘Fast Radio Bursts (FRBs) are intense radio flashes from the sky that are characterized by mil- lisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discovered. Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be ~ 660 pc cm-3, supporting their being from a cosmological origin. Their energy released in the radio band spans about two orders of magnitude, with a mean value of ~ 10-39 erg. More interestingly, although the study of FRBs is still in a very early phase, the published collection of FRBs enables us to derive a useful intensity distribution function. For the 16 non-repeating FRBs detected by the Parkes telescope and the Green Bank Telescope, the intensity distribution can be described as dN/dFobs = (4.1± 1.3) × 103 F-obs1.1±0.2 sky-1 d-l, where Fobs is the observed radio obs fluence in units of Jy ms. Here the power-law index is significantly flatter than the expected value of 2.5 for standard candles distributed homogeneously in a flat Euclidean space. Based on this intensity distribution function, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) is predicted to be able to detect about five FRBs for every 1000 h of observation time.
基金supported by the National Natural Science Foundation of China (21975163, 51902204)。
文摘γ-MnO2 nanorod-assembled hierarchical micro-spheres with abundant oxygen defects are synthesized by a simple thermal treatment approach as oxygen reduction electrocatalysts for Al(aluminum)-air batteries. The rich oxygen vacancies on the surface of γ-MnO2 are verified by morphology, structure,electron paramagnetic resonance(EPR) and X-ray photoelectron spectroscopy(XPS) results. The oxygen reduction reaction(ORR) electrocatalytic activity of γ-MnO2 is significantly improved by the incoming oxygen vacancies. The γ-MnO2 nanorod-assembled hierarchical micro-spheres calcined under 300 °C in Ar atmosphere show the best ORR performance. The primary Al-air batteries using γ-MnO2 catalysts as the cathode, which demonstrates excellent peal power density of 318 m W cm^(-2) when applying theγ-MnO2 catalysts with optimal amount of oxygen vacancies.
基金This study was supported by the National Defense Science and Technology Innovation Zone of China(Grant No.00205501).
文摘The reconstruction control of modular self-reconfigurable spacecraft (MSRS) is addressed using an adaptive sliding mode control (ASMC) scheme based on time-delay estimation (TDE) technology. In contrast to the ground, the base of the MSRS is floating when assembled in orbit, resulting in a strong dynamic coupling effect. A TED-based ASMC technique with exponential reaching law is designed to achieve high-precision coordinated control between the spacecraft base and the robotic arm. TDE technology is used by the controller to compensate for coupling terms and uncertainties, while ASMC can augment and improve TDE’s robustness. To suppress TDE errors and eliminate chattering, a new adaptive law is created to modify gain parameters online, ensuring quick dynamic response and high tracking accuracy. The Lyapunov approach shows that the tracking errors are uniformly ultimately bounded (UUB). Finally, the on-orbit assembly process of MSRS is simulated to validate the efficacy of the proposed control scheme. The simulation results show that the proposed control method can accurately complete the target module’s on-orbit assembly, with minimal perturbations to the spacecraft’s attitude. Meanwhile, it has a high level of robustness and can effectively eliminate chattering.
基金supported by the National Natural Science Foundation of China(Grant Nos.11763005,11622324,11573009,11763002,U1431111 and U1431126)supported by the Research Foundation for Advanced Talents of Liupanshui Normal University(LPSSYKYJJ201506)+3 种基金the Open Fund of Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processingthe Physical Electronic Key Discipline of Guizhou Province(ZDXK201535)the Natural Science Foundation of the Department of Education of Guizhou Province(QJHKYZ[2015]455)the Research Foundation of Liupanshui Normal University(LPSSYDXS1514 and LPSSY201401)
文摘The curvature of the γ-ray spectrum in blazars may reflect the intrinsic distribution of emitting electrons, which will further give some information on the possible acceleration and cooling processes in the emitting region. The γ-ray spectra of Fermi blazars are normally fitted either by a single power-law(PL) or a log-normal(call Logarithmic Parabola, LP) form. The possible reason for this difference is not clear. We statistically explore this issue based on the different observational properties of 1419 Fermi blazars in the 3 LAC Clean Sample. We find that the γ-ray flux(100 Me V–100 Ge V) and variability index follow bimodal distributions for PL and LP blazars, where the γ-ray flux and variability index show a positive correlation. However, the distributions of γ-ray luminosity and redshift follow a unimodal distribution. Our results suggest that the bimodal distribution of γ-ray fluxes for LP and PL blazars may not be intrinsic and all blazars may have an intrinsically curved γ-ray spectrum, and the PL spectrum is just caused by the fitting effect due to less photons.
基金Supported by the National Natural Science Foundation of China.
文摘Using 64 ms count data of long gamma-ray bursts (T90 〉 2.6 s), we analyze the quantity named relative spectral lag (RSL), T31/FWHM(1). We investigated in detail all the correlations between the RSL and other parameters for a sample of nine long bursts, using the general cross-correlation technique that includes the lag between two different energy bands. We conclude that the distribution of RSLs is normal and has a mean value of 0.1; that the RSLs are weakly correlated with the FWHM, the asymmetry, peak flux (Fp), peak energy (Ep) and spectral indexes (α and β), while they are uncorrelated with τ31, the hardness- ratio (HR31) and the peak time (tm). Our important discovery is that redshift (z) and peak luminosity (Lp) are strongly correlated with the RSL, which can be measured easily and directly, making the RSL a good redshift and peak luminosity indicator.
文摘As a result of an error by the authors,in the paper,one of the authors’names,“Xu-Juan Li”,was misspelled.The correct spelling of the name should be“Xiu-Juan Li”.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(2021YFC0863400)Institute of Zoology,Chinese Academy of Sciences(E0517111,E122G611)。
文摘The coronavirus disease 2019(COVID-19)pandemic has greatly damaged human society,but the origins and early transmission patterns of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)pathogen remain unclear.Here,we reconstructed the transmission networks of SARS-CoV-2 during the first three and six months since its first report based on ancestor-offspring relationships using BANAL-52-referenced mutations.We explored the position(i.e.,root,middle,or tip)of early detected samples in the evolutionary tree of SARS-CoV-2.In total,6799 transmission chains and 1766 transmission networks were reconstructed,with chain lengths ranging from 1-9 nodes.The root node samples of the 1766 transmission networks were from 58 countries or regions and showed no common ancestor,indicating the occurrence of many independent or parallel transmissions of SARS-CoV-2 when first detected(i.e.,all samples were located at the tip position of the evolutionary tree).No root node sample was found in any sample(n=31,all from the Chinese mainland)collected in the first 15 days from 24 December 2019.Results using six-month data or RaTG13-referenced mutation data were similar.The reconstruction method was verified using a simulation approach.Our results suggest that SARS-CoV-2 may have already been spreading independently worldwide before the outbreak of COVID-19 in Wuhan,China.Thus,a comprehensive global survey of human and animal samples is essential to explore the origins of SARS-CoV-2 and its natural reservoirs and hosts.
基金Project supported by the Yunnan Fundamental Research Projects(Grant No.202201AU070065)Natural Science Foundation of China for Young Scholars(Grant No.52002131)+1 种基金Open Fund of the Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques(Grant No.2021-04)the Scientific Research Fund Project of Yunnan Provincial Department of Education(Grant No.2022J0591)
文摘A 135 mW single-frequency distributed Bragg reflector fiber laser at 1.95μm was obtained based on a Tm:YAG ceramic-derived all-glass fiber.The fiber laser achieved an optical signal-to-noise ratio of~77 d B.Moreover,the threshold and linewidth of the single-frequency laser were measured to be 15.4 mW and 4.5 kHz,respectively.In addition,the measured relative intensity noise was less than-140 d B·Hz^(-1)at frequencies of over 10 MHz.The results show that the as-drawn Tm:YAG ceramic-derived all-glass fiber is highly promising for~2μm single-frequency fiber laser applications.
基金Supported by the National Natural Science Foundation of China
文摘Using the generic hydrodynamic model of gamma-ray burst (GRB) after- glows, we calculate the radio afterglow light curves of low luminosity, high luminosity, failed and standard GRBs in different observational bands of FAST's energy window. The GRBs are assumed to be located at different distances from us. Our results rank the detectability of GRBs in descending order as high luminosity, standard, failed and low luminosity GRBs. We predict that almost all types of radio afterglows except those of low luminosity GRBs could be observed by a large radio telescope as long as the domains of time and frequency are appropriate. It is important to note that FAST can detect relatively weak radio afterglows at a higher frequency of 2.5 GHz for very high redshift up to z = 15 or even more. Radio afterglows of low luminosity GRBs can only be detected after the completion of the second phase of FAST. FAST is expected to significantly expand the sample of GRB radio afterglows in the near future.
基金supported by the Youth Innovations and Talents Project of Shandong Provincial Colleges and Universities(Grant No.201909118)the Natural Science Foundation(Grant Nos.ZR2018MA030,XKJJC201901 and OP201511)supported by a National Research Foundation of Korea Grant funded by the Korean government(NRF2018R1D1A3B070421880 and 2018R1A6A1A06024970)。
文摘Thanks to more and more gamma-ray bursts with measured redshift and extended emission detected by the recent space telescopes,it is urgent and possible to check whether those previous energy correlations still satisfy the particular sample involving only the bursts accompanied by tail radiations.Using 20 long and 22 short bursts with extended emission,we find that the popular γ-ray energy correlations of the intrinsic peak energy versus the isotropic energy(Amati relation) and the intrinsic peak energy versus the peak luminosity(Yonetoku relation) do exist in both short and long bursts.However,it is much better if these gamma-ray bursts with extended emissions are reclassified into two subgroups of E-Ⅰ and E-Ⅱ that make the above energy correlations more tight.As proposed by Zhang et al.,the energy correlations can be utilized to distinguish these kinds of gamma-ray bursts in the plane of bolometric fluence versus peak energy as well.Interestingly,the peculiar short GRB 170817 A belongs to the E-Ⅰ group in the fluence versus peak energy plane,but it is an outlier of both the Amati and Yonetoku relations even though the off-axis effect has been corrected.Furthermore,we compare the radiation features between the extended emissions and the prompt gamma-rays in order to search for their possible connections.Taking into account all these factors,we conclude that gamma-ray bursts with extended emission are still required to model with dichotomic groups,namely E-Ⅰ and E-Ⅱ classes,which hint that they might have different origins.
文摘Objective:To study the correlation of ERCC1 and GSTP1 expression in esophageal cancer tissue with platinum-based chemotherapy sensitivity as well as apoptosis and proliferation gene expression.Methods: Patients with advanced esophageal cancer who accepted PF chemotherapy in our hospital between May 2013 and October 2015 were selected, esophageal cancer tissue was collected before the chemotherapy, the patients were divided into chemotherapy sensitivity group and chemotherapy resistance group according to the effect of chemotherapy, and the expression levels of ERCC1, GSTP1 as well as apoptosis and proliferation genes in esophageal cancer tissue were detected.Results:Protein content and positive protein expression rate of ERCC1 and GSTP1 in esophageal cancer tissue of chemotherapy sensitivity group were significantly lower than those of chemotherapy resistance group, MBP1, DEC1 and PTEN protein content were significantly higher than those of chemotherapy resistance group, and PLCE1, CyclinD1 and PAR2 protein content were significantly lower than those of chemotherapy resistance group;MBP1, DEC1 and PTEN protein content in esophageal cancer tissue with positive ERCC1 and GSTP1 expression were significantly lower than those in esophageal cancer tissue with negative ERCC1 and GSTP1 expression while PLCE1, CyclinD1 and PAR2 protein content were significantly higher than those in esophageal cancer tissue with negative ERCC1 and GSTP1 expression.Conclusion:The highly expressed ERCC1 and GSTP1 in esophageal cancer tissue can decreased the cancer cell sensitivity to platinum-based chemotherapeutics, inhibit cell apoptosis and promote cell proliferation during platinum-based chemotherapy.
基金supported by the National Natural Science Foundation of China(52172035,52025023 and 92163206)Guangdong Major Project of Basic and Applied Basic Research(2021B0301030002)+4 种基金the National Key R&D Program of China(2021YFA1400502)the National Postdoctoral Program for Innovative Talents(BX20230022)Beijing Municipal Science and Technology Project(Z221100005822003)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB33000000)the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘Since the first isolation of graphene by Geim and Novoselov in 2004,this two-dimensional(2D)material has attracted significant attention from the scientific and engineering communities.^(1)Due to its structure with a single layer of covalently bonded sp^(2)-hybridized carbon atoms,graphene has superior mechanical,electrical,optical,and thermal properties.^(2-4)Although mechanical exfoliation remains an ideal method for obtaining highquality graphene,its scalability is severely limited;thus,it is impractical for industrial applications.In pursuit of a method suitable for large-scale production,research has been performed using chemical vapor deposition(CVD)methods for synthesizing graphene on metal substrates.
基金This study was supported by the Natural Science Foundation of China(31991211 to B.L.and 31970235 to L.F.L.)the Shanghai Pujiang Program(19PJ1401500 to L.F.L.),Israel Science Foundation(ISF)-China National Natural Science Foundation(NSFC)collaborative grants to B.L.(32061143001)and A.A.L.(3394/20)a China Postdoctoral Science Foundation grant(2021M690683).
文摘Common wheat(Triticum aestivum,BBAADD)is a major staple food crop worldwide.The diploid progenitors of the A and D subgenomes have been unequivocally identified;that of B,however,remains ambiguous and controversial but is suspected to be related to species of Aegilops,section Sitopsis.Here,we report the assembly of chromosome-level genome sequences of all five Sitopsis species,namely Aegilops bicornis,Ae.longissima,Ae.searsii,Ae.sharonensis,and Ae.speltoides,as well as the partial assembly of the Amblyopyrum muticum(synonym Aegilops mutica)genome for phylogenetic analysis.Our results reveal that the donor of the common wheat B subgenome is a distinct,and most probably extinct,diploid species that diverged from an ancestral progenitor of the B lineage to which the still extant Ae.speltoides and Am.muticum belong.In addition,we identified interspecific genetic introgressions throughout the evolution of the Triticum/Aegilops species complex.The five Sitopsis species have various assembled genome sizes(4.11-5.89 Gb)with high proportions of repetitive sequences(85.99%-89.81%);nonetheless,they retain high collinearity with other genomes or subgenomes of species in the Triticum/Aegilops complex.Differences in genome size were primarily due to independent post-speciation amplification of transposons.We also identified a set of Sitopsis genes pertinent to important agronomic traits that can be harnessed for wheat breeding.These newly assembled genome resources provide a new roadmap for evolutionary and genetic studies of the Triticum/Aegilops complex,as well as for wheat improvement.
基金the Medical Big Data Research Program of Chinese PLA General Hospital(No.2018MBD-20)the Clinical Research Support Program of Chinese PLA General Hospital(No.2016FCCXYY2010).
文摘Background:Epithelial to mesenchymal transition (EMT) is strongly linked with tumor invasion and metastasis, which performs a vital role in carcinogenesis and cancer progression. Emerging evidence suggests that microRNAs (miRNAs) expression are closely associated to EMT by regulating targeted genes. MiR542 has been found to be involved in the EMT program and bound up with various cancers. However, the functions of miR542 and its underlying mechanism in glioblastoma multiforme (GBM) remain largely unknown. In the current study, we investigated the effect of astrocyte elevated gene-1 ( AEG-1) on U251 cells aggressiveness, proliferation, apoptosis, and cell cycle. Methods:The screening of targeted miRNAs was performed, as well as the functional roles and mechanisms of miR542 were explored.Results:MiR542 was selected as the target because of the most significantly differential expression and this high level of expression negatively correlated with cell migration and proliferation, which suggested that miR542 could be a novel tumor suppressor. Moreover, we confirmed that AEG-1 was a direct targeted gene of miR542 by luciferase activity assay, reverse transcription-polymerase chain reaction, and immunoblotting analysis. Furthermore, miR542 suppressed the expression of AEG-1, which upgraded the level of E-cadherin and degraded Vimentin expression contributing to retraining EMT. Conclusion:The in vitro findings demonstrated that miR542 inhibited the migration and proliferation of U251 cells and suppressed EMT through targeting AEG-1, indicating that miR542 may be a potential anti-cancer target for GBM.
基金financially supported by the National Natural Science Foundation of China (Nos.92166105 and 52005053)the High-Tech Industry Science and TechnologyInnovation Leading Program of Hunan Province (No.2020GK2085)+1 种基金the Science and Technology Innovation Program of Hunan Province (No.2021RC3096)the Open Fund of Key Laboratory of New Processing Technology for Nonferrous Metal & Materials Ministry of Education (No.20KF-24)。
文摘Dual-phase high-entropy alloys containing facecentered cubic(fcc) and body-centered cubic(bcc) phases achieve a combination of high strength and high ductility,which attract extensive attention.Compared with singlephase high-entropy alloys,the dual-phase structure generates more complex deformation mechanisms such as structural transformation and interactions between grain boundaries and dislocations during deformation.In order to understand the structural transformation of the dual-phase high-entropy alloy during deformation and its effect on mechanical properties,Al_(0.5)CoCrNiFe high-entropy alloy was prepared and its deformation mechanism was investigated by molecular dynamics simulations combined with experiments.The results show that phase transformation occurred during deformation,and dislocation slip was the main deformation mechanism.In addition,there was significant dislocation pile-up at the interface between fcc and bcc phases after tensile deformation.Temperatures and strain rates significantly affected the mechanical properties and deformation behavior of high-entropy alloys.At low temperature and high strain rate,the dislocation density of the alloy increases after stretching,resulting in the enhancement of tensile strength.
文摘Into the 21st century, remanufacturing engineering has been accepted by more and more people in China. Remanufacturing is an industrial maintenance technology for worn or waste electro-mechanical products using advanced technology, which means the high-level stage for the maintenance and surface engineering. In this paper, a new automotive high velocity arc spraying system was introduced. And three kinds of advanced amorphous and nanocrystalline metastable coatings were developed, including Fe, Ni and Al-based amorphous and nanocrystalline composite coatings. Their research development and applications were introduced. And the development trends of high velocity arc spraying system and advanced metastable surface protective coating materials on the remanu- facturing engineering were indicated.
基金financially supported by the National Key R&D Program of China (No.2018YFC1902400)the National Natural Science Foundation of China (No.51975582)the Program of China Scholarship Council (No.202006420036)。
文摘In this work,the effect of Re alloying on the phase composition,crystal structure,and mechanical properties of NbMoTaWRe_(x) (x=0,0.27,0.57,0.92,1.33) refractory high-entropy alloys (RHEAs) were systematically investigated by combining the calculation of phase diagram(CALPHAD),first-principle calculations and experiment.The theoretical predictions showed good consistency with the experimental results.As the increase in Re content,the theoretical results showed that all considered alloys have a single body-centered cubic (bcc) structure and the lattice constant and ductility were decreased,while the elastic moduli and hardness were improved.To avoid extreme brittleness,a strategic suggestion was given for the design of Re-containing RHEAs in the future.
文摘To the Editor: A 19-year-old man was admitted to the hospital presenting with “skin and sclera yellow staining for 18 years, accompanied by growth retardation.” The patient developed scleral yellowing at 4 months of age, at which time he was diagnosed as having Wilson's disease (WD) and received symptomatic treatment for liver protection. At 9 years of age the patient developed a pale nail bed, clubbing of the fingers and toes, and accompanying growth retardation. A spontaneous fracture of the right upper limb and left pubic bone occurred at 16 years of age. At 17 years of age the patient developed neuropsychiatric symptoms consisting of fatigue, personality changes, mental retardation, numbness, epileptic seizures, and constipation. He required daily glycerin to assist with defecation. At 5 months prior to admission, obvious sternal malformations and anterior sternal processes were present. Family history revealed that his parents were close relatives (cousin-sister relationship) and the patient's cousin died as a result of WD at age of 12 years. The patient's younger brother was 3 years old and also had a history of WD.
基金National Natural Science Foundation of Jiangxi Provice of China (20122BAB205059)
文摘Introduction Psoriasis characterized by red scaly skin lesions clinically is a chronic inflammatory skin disease,and there are 0.53%-11.43% of the adults around the world suffered[1].The pathophysiological changes of psoriasis are characterized by proliferation accelerated in epidermal basal keratinocytes and infiltration of inflammatory cells from epidermis and dermis.Many studies have shown that the occurrence and development of psoriasis is closely related to genes,cell signaling pathways and proliferation.The relationships between peroxisome proliferator-activated receptor-γ(PPARγ) and TGF-β/Smad signaling pathway and psoriasis has been mostly studied in recent years[2].