The electron energy distribution function （EEDF）, predicted by the Boltzmann equation solver BOLSIG＋ based on the two-term approximation, is introduced into the fluid model for simulating the high-power microwave ...The electron energy distribution function （EEDF）, predicted by the Boltzmann equation solver BOLSIG＋ based on the two-term approximation, is introduced into the fluid model for simulating the high-power microwave （HPM） breakdown in argon, nitrogen, and air, and its validity is examined by comparing with the results of particle-in-cell Monte Carlo collision （PIC/MCC） simulations as well as the experimental data. Numerical results show that, the breakdown time of the fluid model with the Maxwellian EEDF matches that of the PIC/MCC simulations in nitrogen; however, in argon under high pressures, the results from the Maxwellian EEDF were poor. This is due to an overestimation of the energy tail of the Maxwellian EEDF in argon breakdown. The prediction of the fluid model with the BOLSIG＋ EEDF, however, agrees very well with the PIC/MCC prediction in nitrogen and argon over a wide range of pressures. The accuracy of the fluid model with the BOLSIG＋ EEDF is also verified by the experimental results of the air breakdown.展开更多
Does the endosperm pose a mechanical resistance on embryonic axis (radicle) growth for lettuce seed (achene) germination? To aid answering this question, the cell wall degrading enzyme, carboxymethylcellulase (CMCase)...Does the endosperm pose a mechanical resistance on embryonic axis (radicle) growth for lettuce seed (achene) germination? To aid answering this question, the cell wall degrading enzyme, carboxymethylcellulase (CMCase) was extracted and assayed from lettuce seeds imbibed for 0 to 12 h, prior to germination. Measuring the loss of viscosity of carboxymethylcellulose, CMCase activity was high in dry seeds, low after 6 h of imbibition, high after 9 and 10 h, and then reduced again after 12 h. Fractions from Sephadex columns showed CMCase activity in three peaks labeled E1, E2, E3. The greatest change in CMCase activity during imbibition was with E3 (molecular weight of about 40,000 Daltons) and some reduction in E2 (molecular weight about 280,000). The RNA synthesis inhibitor, 6-methyl purine, eliminated CMCase activity when present from 4.5 to 7 h of imbibition and the protein synthesis inhibitor, cycloheximide, eliminated CMCase activity when present between 5.5 and 9 h. Imbibition in darkness lowered CMCase activity while 15 min of light at 3.5 h restored it and 30 min of far-red light at 3 h eliminated it. Increasing the imbibition temperature to 35°C under light reduced activity while under darkness, activity was eliminated under 24°C and 35°C. CMCase activity was localized in the endosperm surrounding the embryonic axis (micropylar end) of 9 h imbibed seeds. These observations showed that CMCase was active in degrading the cell wall in the endosperm surrounding the radicle, weakening it, prior to radicle protrusion so that the radicle remains undamaged.展开更多
By combining the microwave propagation theory and the gas breakdown theory, the microwave propagation with the gas breakdown is analyzed theoretically. Particle-in-cell/Monte Carlo collision （PIC/MCC） simulations ar...By combining the microwave propagation theory and the gas breakdown theory, the microwave propagation with the gas breakdown is analyzed theoretically. Particle-in-cell/Monte Carlo collision （PIC/MCC） simulations are carried out to verify the theoretical results. Based on this theoretical method, the breakdown phenomenon of the pulse microwave is analyzed. The results show that the product values of the initial electron density and the propagation length are the criterion to distinguish the pulse peak decline breakdown and the pulse width reduction breakdown. Furthermore, the energy transmission is also studied, which shows that the total output energy is approximately independent of the input electric field if the electric field is not extremely large.展开更多
This work reports that the intensity ratio of spectral lines having similar self-absorption characteristics during laser induced breakdown spectroscopy(LIBS) analysis can become nearly constant over a wide range of ir...This work reports that the intensity ratio of spectral lines having similar self-absorption characteristics during laser induced breakdown spectroscopy(LIBS) analysis can become nearly constant over a wide range of irradiation conditions if the intensities are integrated over a sufficiently long time. It is shown that the plasma temperature and intensity ratio of these spectral lines have temporal similarity. The spectral lines with similar self-absorption properties may be selected to improve the accuracy and consistency of LIBS analysis results under an environment with fluctuating measurement conditions.展开更多
为开发利用蕉柑落果资源,提高蕉柑落果中辛弗林的提取率,并尽量保护蕉柑组织形态完整,对质构保护液质量浓度以及真空气流细胞破壁技术的4个影响因素进行考察;并采用Box-Behnken试验设计及响应面分析对真空气流细胞破壁技术的工艺条件进...为开发利用蕉柑落果资源,提高蕉柑落果中辛弗林的提取率,并尽量保护蕉柑组织形态完整,对质构保护液质量浓度以及真空气流细胞破壁技术的4个影响因素进行考察;并采用Box-Behnken试验设计及响应面分析对真空气流细胞破壁技术的工艺条件进行优化。结果表明,质构保护最佳处理工艺为:首先在质量浓度0.3 g/100 m L的海藻酸钠溶液中浸泡20 min,接着在质量浓度0.15 g/100 m L的氯化钙溶液中浸泡60 min;真空气流细胞破壁前处理最佳工艺为:泄压温度100℃、压力差116 k Pa、停滞时间21 min、泄压3次。此时辛弗林提取率为69.42%,破果率为33.21%;相比直接进行亚临界水提取对照组,破果率下降了12.07%,辛弗林提取率增加了26.94%。展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2013CB328904)the Fundamental Research Funds for the Central Universities,Chinathe Open Research Fund of Key Laboratory of Cognitive Radio and Information Processing of Ministry of Education of China
文摘The electron energy distribution function （EEDF）, predicted by the Boltzmann equation solver BOLSIG＋ based on the two-term approximation, is introduced into the fluid model for simulating the high-power microwave （HPM） breakdown in argon, nitrogen, and air, and its validity is examined by comparing with the results of particle-in-cell Monte Carlo collision （PIC/MCC） simulations as well as the experimental data. Numerical results show that, the breakdown time of the fluid model with the Maxwellian EEDF matches that of the PIC/MCC simulations in nitrogen; however, in argon under high pressures, the results from the Maxwellian EEDF were poor. This is due to an overestimation of the energy tail of the Maxwellian EEDF in argon breakdown. The prediction of the fluid model with the BOLSIG＋ EEDF, however, agrees very well with the PIC/MCC prediction in nitrogen and argon over a wide range of pressures. The accuracy of the fluid model with the BOLSIG＋ EEDF is also verified by the experimental results of the air breakdown.
文摘Does the endosperm pose a mechanical resistance on embryonic axis (radicle) growth for lettuce seed (achene) germination? To aid answering this question, the cell wall degrading enzyme, carboxymethylcellulase (CMCase) was extracted and assayed from lettuce seeds imbibed for 0 to 12 h, prior to germination. Measuring the loss of viscosity of carboxymethylcellulose, CMCase activity was high in dry seeds, low after 6 h of imbibition, high after 9 and 10 h, and then reduced again after 12 h. Fractions from Sephadex columns showed CMCase activity in three peaks labeled E1, E2, E3. The greatest change in CMCase activity during imbibition was with E3 (molecular weight of about 40,000 Daltons) and some reduction in E2 (molecular weight about 280,000). The RNA synthesis inhibitor, 6-methyl purine, eliminated CMCase activity when present from 4.5 to 7 h of imbibition and the protein synthesis inhibitor, cycloheximide, eliminated CMCase activity when present between 5.5 and 9 h. Imbibition in darkness lowered CMCase activity while 15 min of light at 3.5 h restored it and 30 min of far-red light at 3 h eliminated it. Increasing the imbibition temperature to 35°C under light reduced activity while under darkness, activity was eliminated under 24°C and 35°C. CMCase activity was localized in the endosperm surrounding the embryonic axis (micropylar end) of 9 h imbibed seeds. These observations showed that CMCase was active in degrading the cell wall in the endosperm surrounding the radicle, weakening it, prior to radicle protrusion so that the radicle remains undamaged.
基金supported by the National Natural Science Foundation of China(Grant No.11175040)
文摘By combining the microwave propagation theory and the gas breakdown theory, the microwave propagation with the gas breakdown is analyzed theoretically. Particle-in-cell/Monte Carlo collision （PIC/MCC） simulations are carried out to verify the theoretical results. Based on this theoretical method, the breakdown phenomenon of the pulse microwave is analyzed. The results show that the product values of the initial electron density and the propagation length are the criterion to distinguish the pulse peak decline breakdown and the pulse width reduction breakdown. Furthermore, the energy transmission is also studied, which shows that the total output energy is approximately independent of the input electric field if the electric field is not extremely large.
基金supported by the R&D Center for Valuable Recycling (Global-Top R&BD Program) of the Ministry of Environment (Project No. 2016002250003)
文摘This work reports that the intensity ratio of spectral lines having similar self-absorption characteristics during laser induced breakdown spectroscopy(LIBS) analysis can become nearly constant over a wide range of irradiation conditions if the intensities are integrated over a sufficiently long time. It is shown that the plasma temperature and intensity ratio of these spectral lines have temporal similarity. The spectral lines with similar self-absorption properties may be selected to improve the accuracy and consistency of LIBS analysis results under an environment with fluctuating measurement conditions.
文摘为开发利用蕉柑落果资源,提高蕉柑落果中辛弗林的提取率,并尽量保护蕉柑组织形态完整,对质构保护液质量浓度以及真空气流细胞破壁技术的4个影响因素进行考察;并采用Box-Behnken试验设计及响应面分析对真空气流细胞破壁技术的工艺条件进行优化。结果表明,质构保护最佳处理工艺为:首先在质量浓度0.3 g/100 m L的海藻酸钠溶液中浸泡20 min,接着在质量浓度0.15 g/100 m L的氯化钙溶液中浸泡60 min;真空气流细胞破壁前处理最佳工艺为:泄压温度100℃、压力差116 k Pa、停滞时间21 min、泄压3次。此时辛弗林提取率为69.42%,破果率为33.21%;相比直接进行亚临界水提取对照组,破果率下降了12.07%,辛弗林提取率增加了26.94%。
