The investigation of beta-delayed proton decay mode has become a powerful probe to study the proton-rich nuclei and their nuc/eax structure. To study exotic nuclei with extremely low purity produced by the Radioactive...The investigation of beta-delayed proton decay mode has become a powerful probe to study the proton-rich nuclei and their nuc/eax structure. To study exotic nuclei with extremely low purity produced by the Radioactive Ion Beam Line in Lanzhou, we perform an experiment of beta-delayed proton emission of 36,37^Ca under a high-intensity continuous-beam mode. Ions are implanted into a double-sided silicon strip detector, where the subsequent decays are correlated to the preceding implantations in time sequence. The energy spectra of delayed protons from 36,37^Caβ decay, half-lives and decay branching ratios axe measured. The experimental results confirm the previous literature data and some improved results are obtained as well, demonstrating the feasibility of our detection approach and the reliability of our data analysis procedure. This allows for the development of more powerful detection arrays and further research on nuclei closer to proton-drip line on the basis of present work.展开更多
Nitrogen(N) loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practice...Nitrogen(N) loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil(Ferralic Cambisol) after 19 years of mineral(synthetic) and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined: control(CK), chemical nitrogen and potash fertilizer(NK), chemical nitrogen and phosphorus fertilizer(NP), chemical nitrogen, phosphorus and potash fertilizer(NPK) and the NPK with manure(NPKM, 70% N from manure). Based on the soil total N storage change in 0–100 cm depth, ammonia(NH_3) volatilization, nitrous oxide(N_2O) emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments(NK, NP and NPK) showed increased nitrate(NO_3~–) concentration with increasing soil depth, indicating higher leaching potential. However, total NH_3 volatilization loss was much higher in the NPKM(19.7%) than other mineral fertilizer treatments(≤4.2%). The N_2O emissions were generally low(0.2–0.9%, the highest from the NPKM). Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH_3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporationis an essential strategy in N fertilization management in upland red soil cropping system.展开更多
Currently, daylighting ducts system is widely used as a daylighting device. Generally, daylighting duct system efficiently takes light from outside during the day, and conveys daylight to required location through lig...Currently, daylighting ducts system is widely used as a daylighting device. Generally, daylighting duct system efficiently takes light from outside during the day, and conveys daylight to required location through light duct manufactured by high reflectance mirror. Daylighting duct system can convey daylight to underground space that has no windows opening to external space. Daylighting system is composed of light collection part, light guide part and light emission part. Efficiency of daylighting system is depending on type of each part used in the system. However, it is very difficult to estimate exact light flow in the system considering type of the parts. Authors performed measurement experiments to make clear the light flow with real-size model and miniature model of daylighting duct system. We discussed effect of type of the parts on efficiency of daylighting duct system.展开更多
In order to evaluate the secondary aerosol formation potential at a suburban site of Beijing,in situ perturbation experiments in a potential aerosol mass(PAM) reactor were carried out in the winter of 2014.The varia...In order to evaluate the secondary aerosol formation potential at a suburban site of Beijing,in situ perturbation experiments in a potential aerosol mass(PAM) reactor were carried out in the winter of 2014.The variations of secondary aerosol formation as a function of time,OH exposure,and the concentrations of gas phase pollutants and particles were reported in this study.Two periods with distinct secondary aerosol formation potentials,marked as Period Ⅰ and Period Ⅱ,were identified during the observation.In Period Ⅰ,the secondary aerosol formation potential was high,and correlated well to the air pollutants,i.e.,SO2,NO2,and CO.The maximal secondary aerosol formation was observed with an aging time equivalent to about 3 days of atmospheric oxidation.In period Ⅱ,the secondary aerosol formation potential was low,with no obvious correlation with the air pollutants.Meanwhile,the aerosol mass decreased,instead of showing a peak,with increasing aging time.Backward trajectory analysis during the two periods confirmed that the air mass in Period Ⅰwas mainly from local sources,while it was attributed mostly to long distance transport in Period Ⅱ.The air lost its reactivity during the long transport and the particles became highly aged,resulting in a low secondary aerosol formation potential.Our experimental results indicated that the in situ measurement of the secondary aerosol formation potential could provide important information for evaluating the contributions of local emission and long distance transport to the aerosol pollution.展开更多
基金Supported by the National Basic Research Program of China under Grant No 2013CB834404the National Natural Science Foundation of China under Grant Nos 11375268,11475263,U1432246 and U1432127
文摘The investigation of beta-delayed proton decay mode has become a powerful probe to study the proton-rich nuclei and their nuc/eax structure. To study exotic nuclei with extremely low purity produced by the Radioactive Ion Beam Line in Lanzhou, we perform an experiment of beta-delayed proton emission of 36,37^Ca under a high-intensity continuous-beam mode. Ions are implanted into a double-sided silicon strip detector, where the subsequent decays are correlated to the preceding implantations in time sequence. The energy spectra of delayed protons from 36,37^Caβ decay, half-lives and decay branching ratios axe measured. The experimental results confirm the previous literature data and some improved results are obtained as well, demonstrating the feasibility of our detection approach and the reliability of our data analysis procedure. This allows for the development of more powerful detection arrays and further research on nuclei closer to proton-drip line on the basis of present work.
基金supported by the National Key Research and Development Program of China(2016YFD0200301)the open fund of Key Laboratory of Non-point Source Pollution Control,Ministry of Agriculture,China(20130104)the Key Technologies R&D Program of China during the 12th Five-year Plan period(2012BAD14B04)
文摘Nitrogen(N) loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil(Ferralic Cambisol) after 19 years of mineral(synthetic) and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined: control(CK), chemical nitrogen and potash fertilizer(NK), chemical nitrogen and phosphorus fertilizer(NP), chemical nitrogen, phosphorus and potash fertilizer(NPK) and the NPK with manure(NPKM, 70% N from manure). Based on the soil total N storage change in 0–100 cm depth, ammonia(NH_3) volatilization, nitrous oxide(N_2O) emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments(NK, NP and NPK) showed increased nitrate(NO_3~–) concentration with increasing soil depth, indicating higher leaching potential. However, total NH_3 volatilization loss was much higher in the NPKM(19.7%) than other mineral fertilizer treatments(≤4.2%). The N_2O emissions were generally low(0.2–0.9%, the highest from the NPKM). Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH_3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporationis an essential strategy in N fertilization management in upland red soil cropping system.
文摘Currently, daylighting ducts system is widely used as a daylighting device. Generally, daylighting duct system efficiently takes light from outside during the day, and conveys daylight to required location through light duct manufactured by high reflectance mirror. Daylighting duct system can convey daylight to underground space that has no windows opening to external space. Daylighting system is composed of light collection part, light guide part and light emission part. Efficiency of daylighting system is depending on type of each part used in the system. However, it is very difficult to estimate exact light flow in the system considering type of the parts. Authors performed measurement experiments to make clear the light flow with real-size model and miniature model of daylighting duct system. We discussed effect of type of the parts on efficiency of daylighting duct system.
基金supported by the Key Research Program of Chinese Academy of Sciences (No. KJZD-EW-TZ-G06-01-15)the National Natural Science Foundation of China (No. 21407158)the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (No. XDB05010300)
文摘In order to evaluate the secondary aerosol formation potential at a suburban site of Beijing,in situ perturbation experiments in a potential aerosol mass(PAM) reactor were carried out in the winter of 2014.The variations of secondary aerosol formation as a function of time,OH exposure,and the concentrations of gas phase pollutants and particles were reported in this study.Two periods with distinct secondary aerosol formation potentials,marked as Period Ⅰ and Period Ⅱ,were identified during the observation.In Period Ⅰ,the secondary aerosol formation potential was high,and correlated well to the air pollutants,i.e.,SO2,NO2,and CO.The maximal secondary aerosol formation was observed with an aging time equivalent to about 3 days of atmospheric oxidation.In period Ⅱ,the secondary aerosol formation potential was low,with no obvious correlation with the air pollutants.Meanwhile,the aerosol mass decreased,instead of showing a peak,with increasing aging time.Backward trajectory analysis during the two periods confirmed that the air mass in Period Ⅰwas mainly from local sources,while it was attributed mostly to long distance transport in Period Ⅱ.The air lost its reactivity during the long transport and the particles became highly aged,resulting in a low secondary aerosol formation potential.Our experimental results indicated that the in situ measurement of the secondary aerosol formation potential could provide important information for evaluating the contributions of local emission and long distance transport to the aerosol pollution.