We report the discovery of PSR J1909+0122 by the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)as part of the Commensal Radio Astronomy FAST Survey.PSR J1909+0122 has a spin period of 1.257 s and a disper...We report the discovery of PSR J1909+0122 by the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)as part of the Commensal Radio Astronomy FAST Survey.PSR J1909+0122 has a spin period of 1.257 s and a dispersion measure of 186.2 pc cm^(-3).The averaged pulse profile shows two distinct components.We performed a single-pulse study based on a one-hour observation at 1.25 GHz on 2021 August 23.We used a threshold of 5σ_(ep) to measure the nulling fraction(NF)as 63%±1.5%.The longitude-resolved fluctuation spectra and fast Fourier transform spectra of the binary sequences revealed the quasi-periodicity of nulling with a period of 30 rotation periods.We examined the reliability of the periodicity by comparing it to random noise injection.The NF,E,and modulation periodicity P_(M) of PSR J1909+0122 were compared with other periodic nulling pulsars,showing that the source of J1909+0122 has the second largest NF in the population.Long-term timing observations over six months were used to derive the phase-connected ephemeris of this pulsar.The measured P and P values disfavor dipolar geometry for polar gap models,and the prediction for a space-charge-limited flow model in the case of inverse Compton scattering is only just above the death line.In this work,PSR J1909+0122 has revealed possible correlations between nulling behavior and pulsar properties,which will help to shed light on the pulsar emission mechanism and its temporal evolution in future observations.展开更多
[Objectives] The aim was to investigate the effect of cryptotanshinone on apoptosis of human melanoma A375 cells and its related mechanism of mitochondrial pathway.[Methods]The cytotoxic effect of cryptotanshinone on ...[Objectives] The aim was to investigate the effect of cryptotanshinone on apoptosis of human melanoma A375 cells and its related mechanism of mitochondrial pathway.[Methods]The cytotoxic effect of cryptotanshinone on apoptosis of human melanoma A375 cells was detected by MTT colorimetry.The apoptosis of melanoma A375 cells was detected with Annexin V-FITC/PI and observed by fluorescence inverted microscope.The expression of apoptosis-related proteins was detected by Western blotting.[Results]The viability of the A375 cells decreased with the increase of drug concentration.The fluorescence intensity of the cells increased with the treatment time.The expression of pro-apoptotic protein caspase-3 gradually increased,while the expression of apoptosis-inhibiting proteins p-AKT and Bcl-2 gradually reduced.[Conclusions]Cryptotanshinone induces apoptosis of human melanoma A375 cells via AKT signaling pathway,thus exerting a good cytotoxic effect on A375 cells.展开更多
Cryptotanshinone is a natural active ingredient extracted from traditional Chinese medicine Radix Salviae Miltiorrhizae.It has a variety of pharmacological effects,in addition to preventing and treating ischemic disea...Cryptotanshinone is a natural active ingredient extracted from traditional Chinese medicine Radix Salviae Miltiorrhizae.It has a variety of pharmacological effects,in addition to preventing and treating ischemic diseases,coronary artery disease Alzheimer's disease and fighting tumors.The anti-tumor effects are exerted through inhibiting tumor cell proliferation,inducing tumor cell apoptosis,inhibiting tumor metastasis and invasion,inhibiting angiogenesis and regulating reactive oxygen species levels.The studies on the anti-tumor activity and action mechanism of cryptotanshinone in recent years are reviewed in this article.展开更多
Timing newly discovered pulsars requires gradually building up a timing model that connects observations taken days to months apart.This sometimes can be challenging when our initial knowledge of the pulsar’s positio...Timing newly discovered pulsars requires gradually building up a timing model that connects observations taken days to months apart.This sometimes can be challenging when our initial knowledge of the pulsar’s position is arcminutes off from its true position.Such a position error leads to significant arrival time shifts as a result of the Earth’s orbital motion.Traditional down-hill fitting timing algorithms become ineffective when our model predicts the wrong pulse rotations for our next observation.For some pulsars whose model prediction is not too far off,the correct rotation number could be found by trial-and-error methods.For the remaining challenging pulsars,a more generalized method is called for.This paper proposes a GPU-based algorithm that could exhaustively search a large area of trail positions for probable timing solutions.This could help find phase-connected timing solutions for new pulsars using brute force.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)Grant Nos.11988101,1172531312041303,12041304,12203045,12203070,12103013,T2241020the National SKA Program of China(Nos.2020SKA0120200,2022SKA0130100,2022SKA0130104)+5 种基金the Foundation of Science and Technology of Guizhou Province(No.(2021)023)the Foundation of Guizhou Provincial Education Department(Nos.KY(2021)303,KY(2020)003)support from the National Natural Science Foundation of China under grant U2031117the Youth Innovation Promotion Association CAS(id.2021055)CAS Project for Young Scientists in Basic Research(grant YSBR006)the Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CAS。
文摘We report the discovery of PSR J1909+0122 by the Five-hundred-meter Aperture Spherical Radio Telescope(FAST)as part of the Commensal Radio Astronomy FAST Survey.PSR J1909+0122 has a spin period of 1.257 s and a dispersion measure of 186.2 pc cm^(-3).The averaged pulse profile shows two distinct components.We performed a single-pulse study based on a one-hour observation at 1.25 GHz on 2021 August 23.We used a threshold of 5σ_(ep) to measure the nulling fraction(NF)as 63%±1.5%.The longitude-resolved fluctuation spectra and fast Fourier transform spectra of the binary sequences revealed the quasi-periodicity of nulling with a period of 30 rotation periods.We examined the reliability of the periodicity by comparing it to random noise injection.The NF,E,and modulation periodicity P_(M) of PSR J1909+0122 were compared with other periodic nulling pulsars,showing that the source of J1909+0122 has the second largest NF in the population.Long-term timing observations over six months were used to derive the phase-connected ephemeris of this pulsar.The measured P and P values disfavor dipolar geometry for polar gap models,and the prediction for a space-charge-limited flow model in the case of inverse Compton scattering is only just above the death line.In this work,PSR J1909+0122 has revealed possible correlations between nulling behavior and pulsar properties,which will help to shed light on the pulsar emission mechanism and its temporal evolution in future observations.
基金Supported by Multigrain Production and Processing Characteristic Discipline Construction ProjectPostdoctoral Scientific Research Foundation of Heilongjiang Province of China(LBH-Q13132)
文摘[Objectives] The aim was to investigate the effect of cryptotanshinone on apoptosis of human melanoma A375 cells and its related mechanism of mitochondrial pathway.[Methods]The cytotoxic effect of cryptotanshinone on apoptosis of human melanoma A375 cells was detected by MTT colorimetry.The apoptosis of melanoma A375 cells was detected with Annexin V-FITC/PI and observed by fluorescence inverted microscope.The expression of apoptosis-related proteins was detected by Western blotting.[Results]The viability of the A375 cells decreased with the increase of drug concentration.The fluorescence intensity of the cells increased with the treatment time.The expression of pro-apoptotic protein caspase-3 gradually increased,while the expression of apoptosis-inhibiting proteins p-AKT and Bcl-2 gradually reduced.[Conclusions]Cryptotanshinone induces apoptosis of human melanoma A375 cells via AKT signaling pathway,thus exerting a good cytotoxic effect on A375 cells.
基金Supported by Multigrain Production and Processing Characteristic Discipline Construction ProjectPostdoctoral Scientific Research Foundation of Heilongjiang Province of China(LBH-Q13132)
文摘Cryptotanshinone is a natural active ingredient extracted from traditional Chinese medicine Radix Salviae Miltiorrhizae.It has a variety of pharmacological effects,in addition to preventing and treating ischemic diseases,coronary artery disease Alzheimer's disease and fighting tumors.The anti-tumor effects are exerted through inhibiting tumor cell proliferation,inducing tumor cell apoptosis,inhibiting tumor metastasis and invasion,inhibiting angiogenesis and regulating reactive oxygen species levels.The studies on the anti-tumor activity and action mechanism of cryptotanshinone in recent years are reviewed in this article.
基金supported by the National Natural Science Foundation of China(12041303)the National SKA Program of China(2020SKA0120200)+2 种基金the CAS Project for Young Scientists in Basic Research YSBR-063the National Natural Science Foundation of China(NSFC grant Nos.12203070 and Nos.12203072)the CAS-MPG LEGACY project。
文摘Timing newly discovered pulsars requires gradually building up a timing model that connects observations taken days to months apart.This sometimes can be challenging when our initial knowledge of the pulsar’s position is arcminutes off from its true position.Such a position error leads to significant arrival time shifts as a result of the Earth’s orbital motion.Traditional down-hill fitting timing algorithms become ineffective when our model predicts the wrong pulse rotations for our next observation.For some pulsars whose model prediction is not too far off,the correct rotation number could be found by trial-and-error methods.For the remaining challenging pulsars,a more generalized method is called for.This paper proposes a GPU-based algorithm that could exhaustively search a large area of trail positions for probable timing solutions.This could help find phase-connected timing solutions for new pulsars using brute force.
