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1.
LanPing Wang LanLan Nie DaWei Liu Mounir Laroussi XinPei Lu 《Plasma Processes and Polymers》2023,20(10):e2300038
This work investigates the temporal dynamics of O atoms in nonequilibrium atmospheric pressure plasma (NAPP) generated by kHz nanosecond pulsed discharge. Two-photon laser-induced fluorescence (TALIF) method is used to measure the time resolution of O atom density from the first discharge pulse in two gas mixtures, He + 0.4%O2 and He + 0.4%air. The discharge frequencies of 1 and 10 kHz are considered in the experiment. The results show that the O atom density does not accumulate with increasing number of pulses in both gas environments at 1 kHz. However, at 10 kHz, a cumulative effect of O atom density with the number of pulses is observed in both gas mixtures. After 10 and 300 discharge pulses in He + 0.4%O2 and He + 0.4%air, respectively, the O atom density saturates at the same moment after each discharge cycle. It was found that even after a long operating period of discharge, the decay of O atom density during each discharge cycle is not negligible. The O atom density in He + 0.4%O2 varies in the range of 2.85 × 1021 m−3–4.29 × 1021 m−3 while the O atom density in He + 0.4%air varies in the range of 2.60 × 1021 m−3–3.19 × 1021 m−3. This indicates that the choice of diagnostic time points is important for the O atom density measurements when using TALIF to diagnose kHz pulsed NAPP. In addition, 0D plasma chemical kinetics models are developed for the two gas mixtures to investigate O atoms' production and consumption processes. The causes of the cumulative effect of O atom density at 10 kHz, the saturation effect, and the formation of the periodic variation trend are also investigated. The simulation results show that the consumption rate of O atoms and the O atom density are directly correlated. As the number of pulses increases, the O atom consumption rate increases, which gradually counteracts the number of O atoms generated during the pulse discharge. This leads to delay and saturation of the cumulative effect of O atoms. 相似文献
2.
GUO LanLan FENG ZaoDong LI XinQing LIU LianYou WANG LiXia 《科学通报(英文版)》2007,52(7):959-966
A 5.3 m lake core was drilled in Baahar Nuur Lake in the Ordos Plateau, and measurements of meangrain size, organic δ 13C (δ 13Corg), organic carbon content (TOC), C/N, carbonate content, carbonate δ 13C(δ 13Ccar) and δ 18O (δ 18Ocar) were conducted for retrieving the Holocene chronosequence of climaticchanges based on 15 AMS 14C dates. The record documented four major stages of climate change inthe Ordos Plateau: (IV) a cold and dry condition before ～7.65 14C ka BP; (III) a warm and humid stagebetween ～7.65 and ～5.40 ka BP; (II) a generally drier and cooler climate since ～5.40 ka BP with twohumid events occurring from ～4.70 to ～4.60 ka BP and from ～4.20 to ～3.70 ka BP, and (I) a dry climatecharacterized by complete desiccation of the lake after 3.70 ka BP. Stage III can be further divided intothree sub-stages: (IIIa) a warm and humid episode from ～7.65 to ～6.70 ka BP, (IIIb) a warm and relativelydry episode from ～6.70 to ～6.20 ka BP, and (IIIc) the magthermal and maghumid episode of the Holo-cene from ～6.20 to ～5.40 ka BP. 相似文献
3.
光伏太阳能电池生产过程中的污染问题 总被引：12，自引：0，他引：12
日益壮大的光伏产业正在为人类发展作出积极的贡献.采用光伏发电来代替传统的发电技术,将会减少89%的空气污染.然而,在这个倡导绿色环境的时代,光伏器件生产引起的环境、健康和安全（EHS）问题也日益引起社会各界的广泛关注.认清光伏产品在生产过程中污染的真相对维持光伏产业的可持续发展有着相当重要的意义.本文综述了常见太阳能电池的EHS问题,并提出了可以减少污染的有效途径;采用生命周期评估（LCA）方法进一步比较了各种太阳能电池生产过程中污染物的排放量数据. 相似文献
4.
To understand the origin and its climatic implications of the Huguang Maar sediments, we conducted laser grain size analysis and rock mangtic measurement for the recent deposits from the Huguang Maar and for the volcanic rocks of the caldera for comparison. The grain size distributions are dominated by clayey silts for both the bulk sediments and magnetic separates. Acquisition of isothermal remanent magnetization (IRM) and thermal demagnetization of IRM suggest (titano) magnetite as the dominating magnetic mineral in the sediments; high coercivity minerals are not detected. Therefore, the ratio of the susceptibility of anhysteretic remanent magnetization (k ARM) to the weak field magnetic susceptibility (k), k ARM/k can be used to estimate the grain size of magnetite. The sediments and volcanic rocks yield values of 13.7 and 11.8 for the k ARM/k, respectively, corresponding to grain size values of ～0.03 µm and ～0.05 µm. The magnetic granulometry of lake sediments is distinctive from one of the Chinese loess, in which published data suggest a value of 6.0 for k ARM/k, and grain size of ～0.1 µm, but is akin to the nearby volcanic rocks. Although a Loess Plateau source of the lake sediments cannot be fully ruled out, the catchment is most probably the main source. We explain the slightly finer magnetite grain size in sediments than in the volcanic rocks as being disintegrated of particles during erosion and transportation. We conclude that there is no evidence for aeolian input of the Loess Plateau dusts into the Huguang Maar, and the relationship between magnetic parameters of the lake sediments and winter monsoon intensity is probably more complicated than previously thought. 相似文献
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In this paper, a three-level coupled rotating electrodes air plasma at atmospheric pressure is developed for evaluation of nitrogen fixation. Factors influencing the NOx production rate and energy cost, including airflow rate, the input H2O concentration, blade numbers at each rotating electrode and rotating speed, are examined. Air flow rates prove to have no effect on the rotational temperature of N2 337.1 nm and the emission intensities of N2+ and N2, but specific energy input (SEI) and species’ residence time can be shorter with higher air flow rates, resulting in lower NOx concentration and energy cost. The addition of H2O also has a positive effect on both NOx concentration and energy cost. Optical emission spectrum (OES) shows that air?+?H2O plasma has stronger 336 nm (NH) and 309 nm (OH) emission lines than air plasma, suggests NH and OH are the key species in NOx enhancement. The most energy efficient conditions are found at airflow rate of 15 l min?1, 12% H2O concentration, with 4 blades on each rotating speed. Under these conditions, the lowest energy cost is observed to be 165 GJ/tN.
相似文献7.
运用点偶极、单极跃迁电荷和跃迁密度等经典库仑作用的方法,考察了叶绿素a分子间面心距和错位结构等因素对激子耦合的影响．结果表明,当分子间距大于分子尺寸时,上述三种方法得到的结果基本一致;但当分子间距小于分子尺寸时,点偶极方法将明显高估激子耦合,跃迁密度的方法更适合计算分子间的激子耦合．此外,还使用上述方法计算了光系统Ⅰ（PSI）反应中心叶绿素a分子间激子耦合．结果表明,用跃迁密度计算PSI晶体结构（1jb0．pdb）e700的激子耦合为75.3cm^-1,而QM．MM优化的结构P700（ecAl．ecBl）的激子耦合为23．8cm^-1,这与考虑Dexter交换项的全对角化方法的结果（20cm^-1）一致,进而说明PSI反应中心并不是传统的P700强激子耦合对,而是ecAl-ecB2和ecBl-ecA2对强耦合二聚体构成的二聚体对． 相似文献
8.
Using cDNA microarray hybridization from a human testicular cDNA library, one gene exhibiting ten-fold difference at expression level between adult and embryo human testes was cloned and named NYD-SP9, which was believed to be involved in spermatogenesis. Southern blot hybridization results showed that NYD-SP9 expressed highly in testis but low in ovary. Protein motif analysis of this cDNA sequence revealed a cluster of phosphorylation sites, indicating its potential involvement in signal pathways during spermatogenesis. Furthermore, one transmembrane helix was predicted in N-terminal region, indicating that putative NYD-SP6 may be served as a transmembrane protein. The proximity of these potential phosphorylation sites to each other indicates that there may be interaction among these sites to regulate spermatogenesis. These findings suggested that protein kinase NYD-SP9 might play a role in male germ cell differentiation. 相似文献
9.
One of the main barriers stopping plasma activated water (PAW) in many practical applications is its high energy cost. On the other hand, a careful review of published literature finds that all the studies reported on the PAW only focus on the reactive species generated in liquid, and there is no measurement of the possible reactive species in the gas phase during the generation of PAW, which might contain high concentration reactive species especially for the cases when gas bubbling is used during the generation of PAW. In this paper, an electrodeless plasma device is reported, where distilled water, tap water, and saline water are used as working liquid while O2, N2, and air are flowing through the liquid. Not only the reactive species presented in the liquid phase, the reactive species contained in the gas phase were analyzed for the first time in the field of PAW nitrogen fixation. It was found that the total number of moles of reactive species in gas phase is actually several times higher than that in liquid phase. Only when considering the reactive nitrogen species (RNS) in the liquid phase, the lowest energy cost is about 18.97 MJ/mol when air is flowing though the tap water. On the other hand, when both the RNS in liquid phase and in gas phase are included, the lowest energy cost achieved is 5.53 MJ/mol when air is flowing through distilled water, which is only one-seventh of the lowest energy cost reported on PAW. This study helps us shed light on plasma nitrogen fixation by using PAW, which has been greatly underestimated due to the overlooking of gas phase products of PAW in the past. 相似文献
10.
Di Tian Yang Lv LanLan Nie Xu Li Jialin Liu XinPei Lu 《Plasma Processes and Polymers》2023,20(9):e2200216
Low-temperature plasma is a new transdermal drug delivery method that is different from the traditional physical and chemical methods. In this study, three touchable plasma jet devices are selected, such as direct current (DC) air plasma jet, DC helium plasma jet, and pulsed helium plasma jet. The patent blue V 1159.43 Da has been chosen for percutaneous penetration studies. The results show that 1 min DC air and helium plasma treatment significantly enhanced transdermal drug delivery by 9 and 26 times, respectively. The enhancement of pulsed plasma jet is the weakest. The skin histological analysis and reactive oxygen species (ROS) measurement shows that nonuniform distribution of ROS in DC helium and DC air plasma may cause perforation on the whole epidermis and allow more drug permeation. 相似文献