Long-term monitoring of environmental warfare agengts is a challenge for chemical gas sensors.To address this issue,we developed a 433 MHz passive wireless surface acoustic wave(WSAW)gas sensor for dimethyl methylphos...Long-term monitoring of environmental warfare agengts is a challenge for chemical gas sensors.To address this issue,we developed a 433 MHz passive wireless surface acoustic wave(WSAW)gas sensor for dimethyl methylphosphonate(DMMP)detection.This WSAW gas sensor includes a YZ lithium niobate(LiNbO_(3))substrate with metallic interdigital transducers(IDTs)etched on it,and an antenna was placed near the IDT.A DMMP-sensitive viscoelastic polymer fluoroalcoholpolysiloxane(SXFA)film was prepared on a LiNbO_(3) substrate,and mode modeling coupling was used to optimize the design parameters.The sensor can function properly in an environments between−30℃ and 100℃ with humidity less than 60%RH.When the wireless transmission distance was within the range of 0-90 cm,the sensor noise increased with distance,and the stability was less than 32°/h.While optimizing the film thickness of SXFA,a relationship was observed between sensor sensitivity and film thickness.When the film thickness of SXFA reached 450 nm,the optimal value was reached.At a distance of 20 cm between the transmitting and receiving antennas,DMMP was detected at different concentrations with the developed WSAW gas sensor.The lower detection limit of DMMP was 0.48 mg/m^(3),the sensitivity of the sensor was 4.63°/(mg/m^(3)),and repeatable performance of the sensor was confirmed.展开更多
Due to the coupling effects between stresses in different directions,the mechanical behavior of an ad-vanced composite material under multiaxial loading is extremely complex.In this study,the influence of through-thic...Due to the coupling effects between stresses in different directions,the mechanical behavior of an ad-vanced composite material under multiaxial loading is extremely complex.In this study,the influence of through-thickness compressive stress on the interlaminar shear performance of a carbon fiber-reinforced composite was experimentally investigated.Hollow cylindrical unidirectional laminate specimens were fabricated to conduct combined compression-shear tests,and the fracture morphologies of the specimens were characterized to reveal their failure behavior.The results indicate that a moderate compression load significantly enhanced the shear properties of the laminate by inhibiting crack propagation and improv-ing the friction effect.The shear strength and modulus of a laminate specimen subjected to combined stresses improved up to a maximum of 76%and 231%,respectively,over those of an equivalent specimen subjected to pure shear.However,as the applied through-thickness load approached the compressive strength of the laminate,the specimen shear capacity began to decline owing to the transition of frac-ture mechanisms.Indeed,the specimens exhibited mixed failure modes corresponding to the different stress states,which were induced by the combined effects of through-thickness compressive and shear stresses.As the applied through-thickness compressive stress increased,the dominant failure mode of the laminate specimen changed from fiber-matrix debonding to fiber shearing and then to fiber break-age,resulting in various shear performances.展开更多
A single particle aerosol mass spectrometer was deployed to measure the changes of single particle species and sizes during March 2015 in Weizhou Island of the Beibu Gulf, Guangxi province, South China. In this campai...A single particle aerosol mass spectrometer was deployed to measure the changes of single particle species and sizes during March 2015 in Weizhou Island of the Beibu Gulf, Guangxi province, South China. In this campaign, a total of 3,100,597 particles were sized, and 25.8%particles with both positive and negative mass spectrum were collected and 24.8%characterized in combination with the ART-2 a neural network algorithm. The distribution of sized particles was mainly in from 520 to 600 nm, and the diameters ranging from 340 to1000 nm accounted for above 90%. Eight types of particles were classified： Elemental Carbon containing（EC）, Organic Carbon containing（OC）, EC and OC combined containing particles,Na containing particles, K containing particles（K）, Levoglucosan containing particles,mineral containing particles, and Heavy Metal containing particles（HM）. EC, OC and K were the major containing particles, which accounted for 84.3% in the eight types particles. The relative ratio and size distribution of the three types were EC（48.1%, 620 nm）, OC（12.7%,440 nm）, and K（23.5%, 600 nm）, respectively. The three types of particles were a bit increasing ratios compared with those in clean periods during haze pollution periods.Combined with the back-trajectory results from the Hysplit-4 model and local pollution sources revealed that the ambient air quality on the Weizhou Island may be influenced by biomass burning in the Indochina Peninsula（biomass burning in the Indochina Peninsula）from the transportation on higher level atmospheric layer and by mainland of south China located northeast of Weizhou Island on the ground.展开更多
A Chinese Compilation of Physical Activities was compiled to estimate the energy costs of physical activities(PAs)using data on adults aged 18–64.Data were obtained from published articles and laboratory measurements...A Chinese Compilation of Physical Activities was compiled to estimate the energy costs of physical activities(PAs)using data on adults aged 18–64.Data were obtained from published articles and laboratory measurements.Databases,including PubMed,Embase,Scopus,Ebsco,Web of Science,Chinese National Knowledge Infrastructure,Wan Fang Data,National Science and Technology Report Service,Public Health Scientific Data were searched to collect data from inception to January 2022,on energy expenditure associated with PA in the healthy Chinese population.Two reviewers independently screened the literature and extracted,classified,and summarized data.Data were measured for 36 PAs using indirect calorimetry.Detailed descriptions of specific activities and metabolic equivalent values were provided by summarizing 241 physical activities in 13 categories.The first edition of the Chinese Compilation of PAs in Healthy Adults Aged 18–64(CCPA)was created.It provides valuable resources for people who regularly engage in physical exercise,researchers,educators,fitness professionals,and health or commercial sectors to quickly obtain various PA MET intensities.In the future,the energy expenditure of various PAs of different ages within the Chinese population can be measured based on the CCPA.展开更多
基金supported by the National Natural Science Foundation of China[grant number 42205121]the Natural Science Foundation of Guangxi Province[grant number 2018JJA150164]the Guangxi Engineering Technology Research Center of Source Analysis and Forecasting of Air Pollution.
文摘Long-term monitoring of environmental warfare agengts is a challenge for chemical gas sensors.To address this issue,we developed a 433 MHz passive wireless surface acoustic wave(WSAW)gas sensor for dimethyl methylphosphonate(DMMP)detection.This WSAW gas sensor includes a YZ lithium niobate(LiNbO_(3))substrate with metallic interdigital transducers(IDTs)etched on it,and an antenna was placed near the IDT.A DMMP-sensitive viscoelastic polymer fluoroalcoholpolysiloxane(SXFA)film was prepared on a LiNbO_(3) substrate,and mode modeling coupling was used to optimize the design parameters.The sensor can function properly in an environments between−30℃ and 100℃ with humidity less than 60%RH.When the wireless transmission distance was within the range of 0-90 cm,the sensor noise increased with distance,and the stability was less than 32°/h.While optimizing the film thickness of SXFA,a relationship was observed between sensor sensitivity and film thickness.When the film thickness of SXFA reached 450 nm,the optimal value was reached.At a distance of 20 cm between the transmitting and receiving antennas,DMMP was detected at different concentrations with the developed WSAW gas sensor.The lower detection limit of DMMP was 0.48 mg/m^(3),the sensitivity of the sensor was 4.63°/(mg/m^(3)),and repeatable performance of the sensor was confirmed.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFF0500100)the National Natural Science Foundation of China(Grant No.12272358)the Fund support of Science and Technology on Transient Impact Laboratory.
文摘Due to the coupling effects between stresses in different directions,the mechanical behavior of an ad-vanced composite material under multiaxial loading is extremely complex.In this study,the influence of through-thickness compressive stress on the interlaminar shear performance of a carbon fiber-reinforced composite was experimentally investigated.Hollow cylindrical unidirectional laminate specimens were fabricated to conduct combined compression-shear tests,and the fracture morphologies of the specimens were characterized to reveal their failure behavior.The results indicate that a moderate compression load significantly enhanced the shear properties of the laminate by inhibiting crack propagation and improv-ing the friction effect.The shear strength and modulus of a laminate specimen subjected to combined stresses improved up to a maximum of 76%and 231%,respectively,over those of an equivalent specimen subjected to pure shear.However,as the applied through-thickness load approached the compressive strength of the laminate,the specimen shear capacity began to decline owing to the transition of frac-ture mechanisms.Indeed,the specimens exhibited mixed failure modes corresponding to the different stress states,which were induced by the combined effects of through-thickness compressive and shear stresses.As the applied through-thickness compressive stress increased,the dominant failure mode of the laminate specimen changed from fiber-matrix debonding to fiber shearing and then to fiber break-age,resulting in various shear performances.
基金supported by the Innovation Funds for Scientific Research Academy of Guangxi Environmental Protection(No.HKYCX-2015-5)Guangxi key research and development plan for Department of Guangxi Science(No.GUIKEAB16380292)+1 种基金the China Ministry of Environmental Protection's Special Funds for Scientific Research on Public Welfare(No.201309016)the support from the operation and maintenance teams of the environment observation stations in Beihai
文摘A single particle aerosol mass spectrometer was deployed to measure the changes of single particle species and sizes during March 2015 in Weizhou Island of the Beibu Gulf, Guangxi province, South China. In this campaign, a total of 3,100,597 particles were sized, and 25.8%particles with both positive and negative mass spectrum were collected and 24.8%characterized in combination with the ART-2 a neural network algorithm. The distribution of sized particles was mainly in from 520 to 600 nm, and the diameters ranging from 340 to1000 nm accounted for above 90%. Eight types of particles were classified： Elemental Carbon containing（EC）, Organic Carbon containing（OC）, EC and OC combined containing particles,Na containing particles, K containing particles（K）, Levoglucosan containing particles,mineral containing particles, and Heavy Metal containing particles（HM）. EC, OC and K were the major containing particles, which accounted for 84.3% in the eight types particles. The relative ratio and size distribution of the three types were EC（48.1%, 620 nm）, OC（12.7%,440 nm）, and K（23.5%, 600 nm）, respectively. The three types of particles were a bit increasing ratios compared with those in clean periods during haze pollution periods.Combined with the back-trajectory results from the Hysplit-4 model and local pollution sources revealed that the ambient air quality on the Weizhou Island may be influenced by biomass burning in the Indochina Peninsula（biomass burning in the Indochina Peninsula）from the transportation on higher level atmospheric layer and by mainland of south China located northeast of Weizhou Island on the ground.
基金Funding was provided by the National Key R&D Program of China(2018YFC2000600).
文摘A Chinese Compilation of Physical Activities was compiled to estimate the energy costs of physical activities(PAs)using data on adults aged 18–64.Data were obtained from published articles and laboratory measurements.Databases,including PubMed,Embase,Scopus,Ebsco,Web of Science,Chinese National Knowledge Infrastructure,Wan Fang Data,National Science and Technology Report Service,Public Health Scientific Data were searched to collect data from inception to January 2022,on energy expenditure associated with PA in the healthy Chinese population.Two reviewers independently screened the literature and extracted,classified,and summarized data.Data were measured for 36 PAs using indirect calorimetry.Detailed descriptions of specific activities and metabolic equivalent values were provided by summarizing 241 physical activities in 13 categories.The first edition of the Chinese Compilation of PAs in Healthy Adults Aged 18–64(CCPA)was created.It provides valuable resources for people who regularly engage in physical exercise,researchers,educators,fitness professionals,and health or commercial sectors to quickly obtain various PA MET intensities.In the future,the energy expenditure of various PAs of different ages within the Chinese population can be measured based on the CCPA.
