Biomass burning(BB)is a very important emission source that significantly adversely impacts regional air quality.BB produces a large number of primary organic aerosol(POA)and black carbon(BC).Besides,BB also provides ...Biomass burning(BB)is a very important emission source that significantly adversely impacts regional air quality.BB produces a large number of primary organic aerosol(POA)and black carbon(BC).Besides,BB also provides many precursors for secondary organic aerosol(SOA)generation.In this work,the ratio of levoglucosan(LG)to organic carbon(OC)and the fire hotspots map was used to identify the open biomass burning(OBB)events,which occurred in two representative episodes,October 13 to November 30,2020,and April1 to April 30,2021.The ratio of organic aerosol(OA)to reconstructed PM_(2.5)concentration(PM_(2.5)^(*))increased with the increase of LG/OC.When LG/OC ratio is higher than 0.03,the highest OA/PM_(2.5)^(*)ratio can reach 80%,which means the contribution of OBB to OA is crucial.According to the ratio of LG to K^(+),LG to mannosan(MN)and the regional characteristics of Longfengshan,it can be determined that the crop residuals are the main fuel.The occurrence of OBB coincides with farmers’preferred choices,i.e.,burning biomass in“bright weather”.The“bright weather”refers to the meteorological conditions with high temperature,low humidity,and without rain.Meteorological factors indirectly affect regional biomass combustion pollution by influencing farmers’active choices.展开更多
The Nucleic Acid Laboratory,a division of the Clinical Laboratory Department,is responsible for performing real-time PCR(qPCR)assays to rapidly detect infectious diseases,genetic disorders,and more[1].As the gold stan...The Nucleic Acid Laboratory,a division of the Clinical Laboratory Department,is responsible for performing real-time PCR(qPCR)assays to rapidly detect infectious diseases,genetic disorders,and more[1].As the gold standard,qPCR has played an indispensable role in diagnosing pandemic infections,such as the coronavirus disease 2019(COVID-19)[2].展开更多
To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal ...To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal detection scheme. In this paper, we first analyse BSR system for different amplitudes of 4-ary PAM signals. The steadystate of the bistable system will be statistically distinct, and the feasibility of the proposed detection scheme is confirmed. On this basis, we present a detailed study on steady-state transitions of the BSR system, and an explicit expression of the bistable system parameters is derived. By setting the bistable system parameters, bistable system, 4-ary PAM signal, and noise reach the resonance state, and the BSR-based detection scheme is implemented. Moreover, we derive an analytical expression to calculate the symbol error rate(SER) of 4-ary PAM signals with the BSR-based detection under additive white Gaussian noise(AWGN). Finally, the simulation results validate that BSR-based detection scheme can improve the detection performance while efficiently reducing the symbol error rate.展开更多
Black carbon(BC) has importance regarding aerosol composition, radiative balance, and human exposure. This study adopted a backward-trajectory approach to quantify the origins of BC from anthropogenic emissions(BCAn) ...Black carbon(BC) has importance regarding aerosol composition, radiative balance, and human exposure. This study adopted a backward-trajectory approach to quantify the origins of BC from anthropogenic emissions(BCAn) and open biomass burning(BCBB) transported to Xishuangbanna in 2017. Haze months, between haze and clean months, and clean months in Xishuangbanna were defined according to daily PM_(2.5)concentrations of >75, 35–75, and<35 μg/m^(3), respectively. Results showed that the transport efficiency density(TED) of BC transported to Xishuangbanna was controlled by the prevailing winds in different seasons.The yearly contributions to the effective emission intensity of BCAnand BCBBtransported to Xishuangbanna were 52% and 48%, respectively. However, when haze occurred in Xishuangbanna, the average BCAnand BCBBcontributions were 23% and 77%, respectively. This suggests that open biomass burning(BB) becomes the dominant source in haze months. Myanmar, India, and Laos were the dominant source regions of BC transported to Xishuangbanna during haze months, accounting for 59%, 18%, and 13% of the total, respectively. Furthermore, India was identified as the most important source regions of BCAntransported to Xishuangbanna in haze months, accounting for 14%. The two countries making the greatest contributions to BCBBtransported to Xishuangbanna were Myanmar and Laos in haze months, accounting for 55% and 13%, respectively. BC emissions from Xishuangbanna had minimal effects on the results of the present study. It is suggested that open BB in Myanmar and Laos, and anthropogenic emissions in India were responsible for poor air quality in Xishuangbanna.展开更多
Aerial access networks are considered by one of the promising solutions for 6G technology with Unmanned Aerial Vehicles(UAVs)acting as aerial relays to fill coverage gaps,enhance line-of-sight communication,and improv...Aerial access networks are considered by one of the promising solutions for 6G technology with Unmanned Aerial Vehicles(UAVs)acting as aerial relays to fill coverage gaps,enhance line-of-sight communication,and improve network performance and user experience.To improve spectrum utilization,this paper studies a UAV-assisted wireless communication network based on Cognitive Radio(CR)and Non-Orthogonal Multiple Access(NOMA)technologies.Considering the presence of potential malicious eavesdroppers in complex practical communication scenarios,multiple transmitting nodes cooperate through UAVs.To enhance physical layer security performance,an efficient low-complexity transmitter-relay selection scheme is proposed,which selects the optimal transmitting node based on link channel quality,referred to as the Suboptimal Node Transmission Strategy(SNTS).To further enhance system security performance,another scheme is proposed,which selects the optimal transmitting node by maximizing the transmission capacity of the far user,known as the Optimal Node Transmission Strategy(ONTS).Under the decode-and-forward relay strategy,the security performance of the network under both schemes is studied.Under the joint constraints imposed by the primary interference power and secondary maximum transmission power,the secrecy outage probability for users is derived and validated through simulations.The results indicate that under identical conditions,as the number of transmitting nodes increases,the probability of establishing a line-of-sight link in ground-air communications rises,leading to a decrease in the system’s secrecy outage probability.Furthermore,in terms of multi-user diversity gain,ONTS significantly outperforms SNTS.However,the computational overhead of ONTS is relatively high.Therefore,when meeting the actual communication needs of users,a trade-off between complexity and performance must be considered.展开更多
To investigate the impacts of relative humidity(RH) on secondary organic aerosol(SOA) concentrations and chemical reactions, the carbonaceous aerosol components [i.e., organic carbon(OC) and element carbon(EC)] were q...To investigate the impacts of relative humidity(RH) on secondary organic aerosol(SOA) concentrations and chemical reactions, the carbonaceous aerosol components [i.e., organic carbon(OC) and element carbon(EC)] were quantified in daily PM2.5 samples collected at a background site in East China during summer 2015. Based on the method of EC-tracer, the concentration of secondary organic carbon(SOC) demonstrated an obvious negative relationship with RH higher than 60%. Moreover, the ratio of SOC/EC also exhibited obvious decreasing trends with increasing RH, indicating negative effects for chemical production of SOA under high RH conditions. Due to high RH,photochemistry was weakened, gaseous oxidant concentrations was lowered(e.g., significantly decreased O3 levels),and the production rates of SOA were relatively low. On the other hand, because of more water uptake under higher RH conditions, the aerosol droplet acidity was reduced and enhancement of SOA formation by acidity was accordingly absent. In addition, high RH also plays an important role in changing viscosity of pre-existing aerosol coatings,which can affect reactive uptake yield of SOA. Overall, the results from this study imply that SOA production may be more associated with photochemical processes, while aqueous-phase chemistry is not very important for some SOA formation in a moist ambient environment. In the ambient atmosphere, oxidant concentrations, reaction rates,airborne species, etc., are highly variable. How do these factors affect SOA yields under given ambient environment warrants further detailed investigations.展开更多
Formation of secondary inorganic aerosol(SIA)was investigated during a six-month long heating season in Harbin,China.Enhanced sulfate formation was observed at high relative humidity(RH),with the same threshold RH(80%...Formation of secondary inorganic aerosol(SIA)was investigated during a six-month long heating season in Harbin,China.Enhanced sulfate formation was observed at high relative humidity(RH),with the same threshold RH(80%)for both colder and warmer measurement periods.Compared to wintertime results from Beijing,the threshold RH was considerably higher in Harbin,whereas the RH-dependent enhancement of sulfur oxidation ratio(SOR)was less significant.In addition,the high RH events were rarely encountered,and for other periods,the SOR were typically as low as~0.1.Therefore,the sulfate formation was considered inefficient in this study.After excluding the several cases with high RH,both SOR and the nitrogen oxidation ratio(NOR)exhibited increasing trends as the temperature increased,with the increase of NOR being sharper.The nitrate to sulfate ratio tended to increase with increasing temperature as well.Based on a semi-quantitative approach,this trend was attributed primarily to the temperature-dependent variations of precursors including SO_(2) and NO_(2).The influence of biomass burning emissions on SIA formation was also evident.With stronger impact of biomass burning,an enhancement in NOR was observed whereas SOR was largely unchanged.The different patterns were identified as the dominant driver of the larger nitrate to sulfate ratios measured at higher concentrations of fine particulate matter.展开更多
This study aimed to evaluate the effect of repeated ovarian stimulation(OS)on the ovarian follicular population and morphology in female mice and its influence on the embryo’s developmental ability,and the profile of t...This study aimed to evaluate the effect of repeated ovarian stimulation(OS)on the ovarian follicular population and morphology in female mice and its influence on the embryo’s developmental ability,and the profile of the ovarian surface epithelium(OSE).A total of 75 mice were enrolled in this experiment and randomly assigned into three groups:repeated ovarian stimulated group[n=25;receiving 5 IU pregnant mare serum gonadotrophin(PMSG)and human chorionic gonadotro-pin(hCG)at 6 day intervals for 5 cycles];single ovarian stimulated group(n=25;receiving 5 IU PMSG and hCG for 1 cycle),and control group(n=25;without additional treatment).The follicle number at various stages and the morphologies were recorded respectively in the three groups.The harvested oocytes or embryos,cleavage rate,good quality embryo rate,and blastocyst production rate were counted and calculated,and the proliferations of ovarian surface epithelium were evaluated respectively.In the three groups,the single ovarian stimulation treatment significantly increased the mean number of ovarian oocytes or embryos(39.25�10.77 one-cell embryos/female);on the other hand,repeated gonadotropin stimulation obtained the lowest mean number(5.15�2.81 eggs/female,P<0.01).Repeated ovarian stimulation also tended to decrease normal follicles of primary follicles(66.67%)and secondary follicles(72.86%),and got the lowest cleavage rate(67.47%),lowest good quality embryo rate(2.41%),and lowest blastocyst production rate(0).The OSE cells adjacent to the antral follicles and corpus luteum(CL)in the repeated ovarian stimulated group(81.8%)had a significantly higher proliferation rate than the other groups.The proliferation rate of the OSE in the single ovarian stimulated group(56.4%)was signifi-cantly higher than that in the control group(37.5%)(P<0.01).In conclusion,single ovarian stimulation may produce more oocytes/embryos.However,repeated gona-dotropin stimulation may have a negative effect on the ovarian follicular quality,the number of mature retrieved oocytes,and the embryo quality,even increasing the chance of ovarian cancer.展开更多
基金supported by the Natural Science Foundation of Heilongjiang Province(No.LH2020D011)the S&T Development Fund of CAMS(No.2020KJ003)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research(No.201913)。
文摘Biomass burning(BB)is a very important emission source that significantly adversely impacts regional air quality.BB produces a large number of primary organic aerosol(POA)and black carbon(BC).Besides,BB also provides many precursors for secondary organic aerosol(SOA)generation.In this work,the ratio of levoglucosan(LG)to organic carbon(OC)and the fire hotspots map was used to identify the open biomass burning(OBB)events,which occurred in two representative episodes,October 13 to November 30,2020,and April1 to April 30,2021.The ratio of organic aerosol(OA)to reconstructed PM_(2.5)concentration(PM_(2.5)^(*))increased with the increase of LG/OC.When LG/OC ratio is higher than 0.03,the highest OA/PM_(2.5)^(*)ratio can reach 80%,which means the contribution of OBB to OA is crucial.According to the ratio of LG to K^(+),LG to mannosan(MN)and the regional characteristics of Longfengshan,it can be determined that the crop residuals are the main fuel.The occurrence of OBB coincides with farmers’preferred choices,i.e.,burning biomass in“bright weather”.The“bright weather”refers to the meteorological conditions with high temperature,low humidity,and without rain.Meteorological factors indirectly affect regional biomass combustion pollution by influencing farmers’active choices.
基金supported by the Basic research and achievement transformation project of Jiulongpo District Science and Technology Bureau[No.2022-02-013-Y].
文摘The Nucleic Acid Laboratory,a division of the Clinical Laboratory Department,is responsible for performing real-time PCR(qPCR)assays to rapidly detect infectious diseases,genetic disorders,and more[1].As the gold standard,qPCR has played an indispensable role in diagnosing pandemic infections,such as the coronavirus disease 2019(COVID-19)[2].
基金supported by the National Natural Science Foundation of China (61631015, 61501354, 61501356, and 61573202)the Fundamental Research Funds of the Ministry of Education (7215433803)+5 种基金the Foundation of State Key Laboratory of Integrated Services Networks (ISN1101002)Higher School Subject Innovation Engineering Plan (B08038)Science and Technology Innovation Team Key Plan of Shaanxi Province (2016KCT-01)The Fundamental Research Funds of the Ministry of Education, China (Grant No. JB160101)The Key Laboratory Foundation of Ministry of Industry and Information Technology (KF20181912)China Postdoctoral Science Foundation (2018M631122)
文摘To boost the performance of 4-ary pulse amplitude modulated(PAM) at low signal-to-noise ratio(SNR), bistable stochastic resonance(BSR) system is introduced into digital communications system and get a reliable signal detection scheme. In this paper, we first analyse BSR system for different amplitudes of 4-ary PAM signals. The steadystate of the bistable system will be statistically distinct, and the feasibility of the proposed detection scheme is confirmed. On this basis, we present a detailed study on steady-state transitions of the BSR system, and an explicit expression of the bistable system parameters is derived. By setting the bistable system parameters, bistable system, 4-ary PAM signal, and noise reach the resonance state, and the BSR-based detection scheme is implemented. Moreover, we derive an analytical expression to calculate the symbol error rate(SER) of 4-ary PAM signals with the BSR-based detection under additive white Gaussian noise(AWGN). Finally, the simulation results validate that BSR-based detection scheme can improve the detection performance while efficiently reducing the symbol error rate.
基金supported by the National Natural Science Foundation of China (Nos. 41705109 and 41805098)State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex (No. SCAPC_(2)02001)+1 种基金State Key Laboratory of Severe Weather & Key Laboratory for Atmospheric Chemistry (No. 2018B04)Tsinghua National Laboratory for Information Science and Technology。
文摘Black carbon(BC) has importance regarding aerosol composition, radiative balance, and human exposure. This study adopted a backward-trajectory approach to quantify the origins of BC from anthropogenic emissions(BCAn) and open biomass burning(BCBB) transported to Xishuangbanna in 2017. Haze months, between haze and clean months, and clean months in Xishuangbanna were defined according to daily PM_(2.5)concentrations of >75, 35–75, and<35 μg/m^(3), respectively. Results showed that the transport efficiency density(TED) of BC transported to Xishuangbanna was controlled by the prevailing winds in different seasons.The yearly contributions to the effective emission intensity of BCAnand BCBBtransported to Xishuangbanna were 52% and 48%, respectively. However, when haze occurred in Xishuangbanna, the average BCAnand BCBBcontributions were 23% and 77%, respectively. This suggests that open biomass burning(BB) becomes the dominant source in haze months. Myanmar, India, and Laos were the dominant source regions of BC transported to Xishuangbanna during haze months, accounting for 59%, 18%, and 13% of the total, respectively. Furthermore, India was identified as the most important source regions of BCAntransported to Xishuangbanna in haze months, accounting for 14%. The two countries making the greatest contributions to BCBBtransported to Xishuangbanna were Myanmar and Laos in haze months, accounting for 55% and 13%, respectively. BC emissions from Xishuangbanna had minimal effects on the results of the present study. It is suggested that open BB in Myanmar and Laos, and anthropogenic emissions in India were responsible for poor air quality in Xishuangbanna.
基金supported by the National Natural Science Foundation of China(Nos.62461032 and 62001359)the Tianyou Youth Talent Lift Program of Lanzhou Jiaotong University,Chinathe Key Research and Development Project of Lanzhou Jiaotong University,China(No.ZDYF2304).
文摘Aerial access networks are considered by one of the promising solutions for 6G technology with Unmanned Aerial Vehicles(UAVs)acting as aerial relays to fill coverage gaps,enhance line-of-sight communication,and improve network performance and user experience.To improve spectrum utilization,this paper studies a UAV-assisted wireless communication network based on Cognitive Radio(CR)and Non-Orthogonal Multiple Access(NOMA)technologies.Considering the presence of potential malicious eavesdroppers in complex practical communication scenarios,multiple transmitting nodes cooperate through UAVs.To enhance physical layer security performance,an efficient low-complexity transmitter-relay selection scheme is proposed,which selects the optimal transmitting node based on link channel quality,referred to as the Suboptimal Node Transmission Strategy(SNTS).To further enhance system security performance,another scheme is proposed,which selects the optimal transmitting node by maximizing the transmission capacity of the far user,known as the Optimal Node Transmission Strategy(ONTS).Under the decode-and-forward relay strategy,the security performance of the network under both schemes is studied.Under the joint constraints imposed by the primary interference power and secondary maximum transmission power,the secrecy outage probability for users is derived and validated through simulations.The results indicate that under identical conditions,as the number of transmitting nodes increases,the probability of establishing a line-of-sight link in ground-air communications rises,leading to a decrease in the system’s secrecy outage probability.Furthermore,in terms of multi-user diversity gain,ONTS significantly outperforms SNTS.However,the computational overhead of ONTS is relatively high.Therefore,when meeting the actual communication needs of users,a trade-off between complexity and performance must be considered.
基金Supported by the National Key Research and Development Program of China(2016YFC0202300 and 2017YFC0212803)Beijing Natural Science Foundation(8192055)+1 种基金State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex(SCAPC201701)Basic Research and Operation Funds of Chinese Academy of Meteorological Sciences(2015Y001 and2017Z011)
文摘To investigate the impacts of relative humidity(RH) on secondary organic aerosol(SOA) concentrations and chemical reactions, the carbonaceous aerosol components [i.e., organic carbon(OC) and element carbon(EC)] were quantified in daily PM2.5 samples collected at a background site in East China during summer 2015. Based on the method of EC-tracer, the concentration of secondary organic carbon(SOC) demonstrated an obvious negative relationship with RH higher than 60%. Moreover, the ratio of SOC/EC also exhibited obvious decreasing trends with increasing RH, indicating negative effects for chemical production of SOA under high RH conditions. Due to high RH,photochemistry was weakened, gaseous oxidant concentrations was lowered(e.g., significantly decreased O3 levels),and the production rates of SOA were relatively low. On the other hand, because of more water uptake under higher RH conditions, the aerosol droplet acidity was reduced and enhancement of SOA formation by acidity was accordingly absent. In addition, high RH also plays an important role in changing viscosity of pre-existing aerosol coatings,which can affect reactive uptake yield of SOA. Overall, the results from this study imply that SOA production may be more associated with photochemical processes, while aqueous-phase chemistry is not very important for some SOA formation in a moist ambient environment. In the ambient atmosphere, oxidant concentrations, reaction rates,airborne species, etc., are highly variable. How do these factors affect SOA yields under given ambient environment warrants further detailed investigations.
基金This work was supported by the National Natural Science Foundation of China(No.41805097)the Natural Science Foundation of Heilongjiang Province(No.YQ2019D004)+3 种基金the State Key Laboratory of Urban Water Resource and Environment(No.ES202006)the State Key Joint Laboratory of Environment Simulation and Pollution Control(No.19K02ESPCT)the State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex(No.SCAPC202002)Heilongjiang Touyan Team.The authors would like to thank Laura E.King for proofreading the paper.
文摘Formation of secondary inorganic aerosol(SIA)was investigated during a six-month long heating season in Harbin,China.Enhanced sulfate formation was observed at high relative humidity(RH),with the same threshold RH(80%)for both colder and warmer measurement periods.Compared to wintertime results from Beijing,the threshold RH was considerably higher in Harbin,whereas the RH-dependent enhancement of sulfur oxidation ratio(SOR)was less significant.In addition,the high RH events were rarely encountered,and for other periods,the SOR were typically as low as~0.1.Therefore,the sulfate formation was considered inefficient in this study.After excluding the several cases with high RH,both SOR and the nitrogen oxidation ratio(NOR)exhibited increasing trends as the temperature increased,with the increase of NOR being sharper.The nitrate to sulfate ratio tended to increase with increasing temperature as well.Based on a semi-quantitative approach,this trend was attributed primarily to the temperature-dependent variations of precursors including SO_(2) and NO_(2).The influence of biomass burning emissions on SIA formation was also evident.With stronger impact of biomass burning,an enhancement in NOR was observed whereas SOR was largely unchanged.The different patterns were identified as the dominant driver of the larger nitrate to sulfate ratios measured at higher concentrations of fine particulate matter.
基金supported by the Special Funds for State Key Development Program for Basic Research of China(973 Program)(No.2007CB948104).
文摘This study aimed to evaluate the effect of repeated ovarian stimulation(OS)on the ovarian follicular population and morphology in female mice and its influence on the embryo’s developmental ability,and the profile of the ovarian surface epithelium(OSE).A total of 75 mice were enrolled in this experiment and randomly assigned into three groups:repeated ovarian stimulated group[n=25;receiving 5 IU pregnant mare serum gonadotrophin(PMSG)and human chorionic gonadotro-pin(hCG)at 6 day intervals for 5 cycles];single ovarian stimulated group(n=25;receiving 5 IU PMSG and hCG for 1 cycle),and control group(n=25;without additional treatment).The follicle number at various stages and the morphologies were recorded respectively in the three groups.The harvested oocytes or embryos,cleavage rate,good quality embryo rate,and blastocyst production rate were counted and calculated,and the proliferations of ovarian surface epithelium were evaluated respectively.In the three groups,the single ovarian stimulation treatment significantly increased the mean number of ovarian oocytes or embryos(39.25�10.77 one-cell embryos/female);on the other hand,repeated gonadotropin stimulation obtained the lowest mean number(5.15�2.81 eggs/female,P<0.01).Repeated ovarian stimulation also tended to decrease normal follicles of primary follicles(66.67%)and secondary follicles(72.86%),and got the lowest cleavage rate(67.47%),lowest good quality embryo rate(2.41%),and lowest blastocyst production rate(0).The OSE cells adjacent to the antral follicles and corpus luteum(CL)in the repeated ovarian stimulated group(81.8%)had a significantly higher proliferation rate than the other groups.The proliferation rate of the OSE in the single ovarian stimulated group(56.4%)was signifi-cantly higher than that in the control group(37.5%)(P<0.01).In conclusion,single ovarian stimulation may produce more oocytes/embryos.However,repeated gona-dotropin stimulation may have a negative effect on the ovarian follicular quality,the number of mature retrieved oocytes,and the embryo quality,even increasing the chance of ovarian cancer.
