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1.
Although electrochemical capacitors (ECs), also known as supercapacitors or ultracapacitors, charge and discharge faster than batteries, they are still limited by low energy densities and slow rate capabilities. We used a standard LightScribe DVD optical drive to do the direct laser reduction of graphite oxide films to graphene. The produced films are mechanically robust, show high electrical conductivity (1738 siemens per meter) and specific surface area (1520 square meters per gram), and can thus be used directly as EC electrodes without the need for binders or current collectors, as is the case for conventional ECs. Devices made with these electrodes exhibit ultrahigh energy density values in different electrolytes while maintaining the high power density and excellent cycle stability of ECs. Moreover, these ECs maintain excellent electrochemical attributes under high mechanical stress and thus hold promise for high-power, flexible electronics.  相似文献   

2.
In 1979 two areas of upwelling were observed off Somalia, one near 10 degrees N and one near 5 degrees N. The areas of upwelling were characterized by sea surface temperatures between 17 degrees and 22 degrees C, high concentrations of surface nutrients (5 to 20 micromoles of nitrate per liter) and surface chlorophyll a (0.4 to 5.0 milligrams per cubic meter), primary productivity averaging 1.7 grams of carbon per square meter per day, and a phytoplankton assemblage dominated numerically by the diatom Nitzschia delicatissima.  相似文献   

3.
L Bennett 《Science (New York, N.Y.)》1967,155(769):1554-1556
Interferometric microscope observations of flowing blood indicate that the absolute number of red cells maintaining sliding contact with a wall is of the order 10(4) per square centi meter at low flow rates. Contacting cell oscillation and orientation results are given. The near wall local hematocrit is found to be relatively low.  相似文献   

4.
以杂交棉鲁棉研25号为试验材料,采用裂区设计,于2008年在山东临清、嘉祥和金乡三地大田条件下研究了种植密度与留叶枝对产量及其构成因素等的互作效应。结果表明:密度和整枝对杂交棉产量、产量构成以及熟相有显著的互作效应。去叶枝情况下,低密度(3.00株/m2)和高密度(7.50株/m2)处理的产量低,中高密度(4.50-6.00株/m2)的产量较高;留叶枝条件下,低密度(3.00株/m2)产量最高,中高密度(4.50-6.00株/m2)的产量居中,而高密度(7.50株/m2)处理的产量还是最低;整枝条件下4.50株/m2密度处理的籽棉和皮棉产量比3.00株/m2分别增产4.93%和5.51%,而留叶枝条件下3.00株/m2的籽棉产量比4.50株/m2高4.03%。低密度(3.00株/m2)下留叶枝的铃数多于去叶枝的铃数,但随密度增加(4.50株/m2及以上),留叶枝的铃数显著少于去叶枝的铃数;留叶枝和增加密度都会降低铃重。密度与整枝对棉柴比没有显著的互作效应,但都可显著影响生物产量。密度与整枝对棉花早熟性也有互作效应,去叶枝的早熟性好于留叶枝的处理,随密度增加,早熟性降低。  相似文献   

5.
The impact of boreal forest fire on climate warming   总被引:1,自引:0,他引:1  
We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 +/- 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (-2.3 +/- 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming.  相似文献   

6.
在无虫网(温)室用扦插法繁殖马铃薯脱毒原原种,成活率99.2%,种植密度400株/m2,经50天左右,可产微型薯近600粒/m2,平均百粒重148.8g,其中1~3g的微薯占50%以上。日产薯当量约为10粒/m2·d,繁殖系数可达1:300以上。  相似文献   

7.
Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp(2)-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.  相似文献   

8.
Ship observations and ocean models indicate that heat export from the mixed layer of the western Pacific warm pool is small (<20 watts per square meter). This value was used to deduce the effect of clouds on the net solar radiation at the sea surface. The inferred magnitude of this shortwave cloud forcing was large ( approximately - 100 watts per square meter) and exceeded its observed value at the top of the atmosphere by a factor of about 1.5. This result implies that clouds (at least over the warm pool) reduce net solar radiation at the sea surface not only by reflecting a significant amount back to space, but also by trapping a large amount in the cloudy atmosphere, an inference that is at variance with most model results. The excess cloud absorption, if confirmed, has many climatic implications, including a significant reduction in the required tropics to extrattropics heat transport in the oceans.  相似文献   

9.
对新优63等9个籼型杂交稻组合的产量性状分析和1991~1994年江西省及南方区试资料比较,结果表明:新优63的单位面积有效穗与生产上一些应用组合无显著差异,单位面积实粒数显著少于部分应用组合,其增产的主要原因是千粒重极显著地高于其他供试组合。进而对新优63的有效穗、每穗总粒数、每穗实粒数、结实率、千粒重等5个经济性状与产量间进行相关和通径分析,进一步表明:该组合千粒重大是其特殊的增产原因。本文指出:通过重粒型组合的选育可能是突破目前三系籼型杂交晚稻组合产量徘徊的一条有效途径  相似文献   

10.
山东生态条件下纯作春棉的适宜密度研究   总被引:3,自引:1,他引:2  
以常规抗虫棉鲁棉研28号为材料,在山东广饶、夏津和冠县三地大田条件下纯作种植,研究了不同密度(3.00~9.00株/m2)下的棉花产量及产量构成。结果表明,种植密度对纯作抗虫棉产量、产量构成以及熟相均有显著的影响,对经济产量的调控效应三个试验点大致相同,都随密度的增加呈现先升后降的趋势。即低密度(3.00株/m2)和高密度(9.00株/m2)处理的产量低,中高密度(4.50~7.50株/m2)的产量较高。三个点平均,6.00株/m2密度处理的籽棉和皮棉产量与4.50株/m2处理相当,但比3.00株/m2分别增产10.1%和12.0%,比9.00株/m2处理分别增产22.3%和22.8%。提高密度能提高单位面积的生物产量和单位面积铃数,但可显著降低棉柴比、铃重和早熟性。密度偏高和偏低都不能获得较高的经济产量和协调的产量结构,山东春棉纯作条件下适宜种植密度为4.50~6.00株/m2。  相似文献   

11.
Cusick RD  Kim Y  Logan BE 《Science (New York, N.Y.)》2012,335(6075):1474-1477
Reverse electrodialysis allows for the capture of energy from salinity gradients between salt and fresh waters, but potential applications are currently limited to coastal areas and the need for a large number of membrane pairs. Using salt solutions that could be continuously regenerated with waste heat (≥40°C) and conventional technologies would allow much wider applications of salinity-gradient power production. We used reverse electrodialysis ion-exchange membrane stacks in microbial reverse-electrodialysis cells to efficiently capture salinity-gradient energy from ammonium bicarbonate salt solutions. The maximum power density using acetate reached 5.6 watts per square meter of cathode surface area, which was five times that produced without the dialysis stack, and 3.0 ± 0.05 watts per square meter with domestic wastewater. Maximum energy recovery with acetate reached 30 ± 0.5%.  相似文献   

12.
Measurement of the effect of Amazon smoke on inhibition of cloud formation   总被引:3,自引:0,他引:3  
Urban air pollution and smoke from fires have been modeled to reduce cloud formation by absorbing sunlight, thereby cooling the surface and heating the atmosphere. Satellite data over the Amazon region during the biomass burning season showed that scattered cumulus cloud cover was reduced from 38%in clean conditions to 0%for heavy smoke (optical depth of 1.3). This response to the smoke radiative effect reverses the regional smoke instantaneous forcing of climate from -28 watts per square meter in cloud-free conditions to +8 watts per square meter once the reduction of cloud cover is accounted for.  相似文献   

13.
Measurements of radon-222 in seawater suggest the following. The radium-226 content of surface water in both the Atlantic and Pacific oceans is uniformly close to about 4 x 10(-14) gram per liter. The deep Pacific has a concentration of radium-226 that is four times higher and the deep Atlantic a concentration twice as high as that of the surface. These distribution profiles can be explained by the same particle-settling rate for radium-226 from surface to depth for the two oceans and by a threefold longer residence time of water in the deep Pacific than in the deep Atlantic. The vertical distribution of the deficiency of radon-222 in the surface water of the northwest Pacific Ocean suggests a coefficient of vertical eddy diffusion as high as 120 square centimeters per second and a gas-exchange rate for carbon dioxide in surface water between 14 and 60 moles per square meter per year. Vertical profiles of the excess of radon-222 in near-bottom water of the South Atlantic give coefficients of vertical eddy diffusion ranging from 1.5 to more than 50 square centimeters per second.  相似文献   

14.
Presently available data on the electrical conductivity of the uppermost lunar surface layers are in accord with the presence of dry, powdered rocks in which the dielectric loss tangent is frequency-independent over several decades of frequency. These powders have typical direct-current conductivity values of about 10(-13) to 10(-16) mhos per meter and dielectric constants of about 3.0, depending on the packing. Thus the surface layers of the moon are likely to have an extremely low electrical conductivity. At high frequencies normal dielectric losses lead to much higher apparent conductivities that are frequency-dependent.  相似文献   

15.
为了研究窄冠速生刺槐在惠水山区的培育技术,进行了插根育苗密度试验和幼林施肥试验。试验结果表明:窄冠速生刺槐最适宜的育苗密度是17株/m2(20 cm×30 cm),其次是22株/m2(15 cm×30 cm),最差50株/m2(10 cm×20 cm);幼林生长第1年最优的施肥组合方式为尿素25 g/株、氯化钾40 g/株。  相似文献   

16.
Etch-decoration reveals that the rate of removal of carbon atoms exposed at monolayer steps on graphite surfaces is very different from the rate of removal, under identical conditions, at multilayer steps. At 1113 degrees K and a pressure of 1.33 newtons per square meter of oxygen, the rate of oxidation (along the layer planes) is less by a factor of nearly 100 than that at multilayer steps.  相似文献   

17.
试验共设5个密度处理,设计播量区间240~660万粒/hm2,变幅105万粒/hm2。结果表明,以庄浪县为代表的旱寒区冬小麦膜侧沟播栽培靠主茎成穗,分蘖成穗率较低。在生产上,合理的群体密度基本苗360万株/hm2,即播量450万粒/hm2左右。  相似文献   

18.
The total heat gained by the North Atlantic Ocean over the past 50 years is equivalent to a basinwide increase in the flux of heat across the ocean surface of 0.4 +/- 0.05 watts per square meter. We show, however, that this basin has not warmed uniformly: Although the tropics and subtropics have warmed, the subpolar ocean has cooled. These regional differences require local surface heat flux changes (+/-4 watts per square meter) much larger than the basinwide average. Model investigations show that these regional differences can be explained by large-scale, decadal variability in wind and buoyancy forcing as measured by the North Atlantic Oscillation index. Whether the overall heat gain is due to anthropogenic warming is difficult to confirm because strong natural variability in this ocean basin is potentially masking such input at the present time.  相似文献   

19.
Preliminary results from solar radiation measurements from the earth radiation budget experiment on the Nimbus 7 satellite yield a mean value of 1376.0 watts per square meter for the "solar constant" from 16 November 1978 to 15 May 1979. The observed variability (root-mean-square deviation) is +/- 0.73 watt per square meter (+/- 0.05 percent) for the period.  相似文献   

20.
Droplets of nonvolatile fuels such as soy oil and glucose-water solutions can be flash evaporated by catalytic partial oxidation to produce hydrogen in high yields with a total time in the reactor of less than 50 milliseconds. Pyrolysis, coupled with catalytic oxidation of the fuels and their fragments upon impact with a hot rhodium-cerium catalyst surface, avoids the formation of deactivating carbon layers on the catalyst. The catalytic reactions of these products generate approximately 1 megawatt of heat per square meter, which maintains the catalyst surface above 800 degrees C at high drop impact rates. At these temperatures, heavy fuels can be catalytically transformed directly into hydrogen, carbon monoxide, and other small molecules in very short contact times without the formation of carbon.  相似文献   

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