High-efficiency organic solar concentrators for photovoltaics

The cost of photovoltaic power can be reduced with organic solar concentrators. These are planar waveguides with a thin-film organic coating on the face and inorganic solar cells attached to the edges. Light is absorbed by the coating and reemitted into waveguide modes for collection by the solar cells. We report single- and tandem-waveguide organic solar concentrators with quantum efficiencies exceeding 50% and projected power conversion efficiencies as high as 6.8%. The exploitation of near-field energy transfer, solid-state solvation, and phosphorescence enables 10-fold increases in the power obtained from photovoltaic cells, without the need for solar tracking.     

Hydrogen-evolving solar cells

Sunlight is directly converted to chemical energy in hydrogen-evolving photoelectrochemical cells with semiconductor electrodes. Their Gibbs free energy efficiency of solar-to-hydrogen conversion, 13.3 percent, exceeds the solar-to-fuel conversion efficiency of green plants and approaches the solar-to-electrical conversion efficiency of the best p-n junction cells. In hydrogen-evolving photoelectrodes, electron-hole pairs photogenerated in the semiconductor are separated at electrical microcontacts between the semiconductor and group VIII metal catalyst islands. Conversion is efficient when the island diameters are small relative to the wave-lengths of sunlight exciting the semiconductor; when the island spacings are smaller than the diffusion length of electrons at the semiconductor surface; when the height of the potential energy barriers that separate the photogenerated electrons from holes at the semiconductor surface is raised by hydrogen alloying of the islands; when radiationless recombination of electron-hole pairs at the semiconductor-solution interface between the islands is suppressed by controlling the semiconductor surface chemistry; and when the semiconductor has an appropriate band gap (1.0 to 1.8 electron volts) for efficient solar conversion.     

Hybrid nanorod-polymer solar cells

We demonstrate that semiconductor nanorods can be used to fabricate readily processed and efficient hybrid solar cells together with polymers. By controlling nanorod length, we can change the distance on which electrons are transported directly through the thin film device. Tuning the band gap by altering the nanorod radius enabled us to optimize the overlap between the absorption spectrum of the cell and the solar emission spectrum. A photovoltaic device consisting of 7-nanometer by 60-nanometer CdSe nanorods and the conjugated polymer poly-3(hexylthiophene) was assembled from solution with an external quantum efficiency of over 54% and a monochromatic power conversion efficiency of 6.9% under 0.1 milliwatt per square centimeter illumination at 515 nanometers. Under Air Mass (A.M.) 1.5 Global solar conditions, we obtained a power conversion efficiency of 1.7%.     

High-efficiency ligation and recombination of DNA fragments by vertebrate cells

DNA-mediated gene transfer (transfection) is used to introduce specific genes into vertebrate cells. Events soon after transfection were quantitatively analyzed by determining the infectivity of the DNA from an avian retrovirus and of mixtures of subgenomic fragments of this DNA. The limiting step of transfection with two DNA molecules is the uptake by a single cell of both DNA's in a biologically active state. Transfected cells mediate ligation and recombination of physically unlinked DNA's at nearly 100 percent efficiency.     

Limits on sensitivity of large silicon bolometers for solar neutrino detection

Estimates are given for ultimate limits on background in proposed direct-counting measurements of neutrino scattering from large silicon crystals. Methods of background reduction are discussed. In the best case, the limiting backgrounds due to activities from cosmic-ray spallation of silicon would be less than the expected true event rate for reactor neutrino measurements of coherent neutral-current scattering from silicon nuclei. Considerable reduction of the estimated high-energy backgrounds would be required for a good signal-to-noise ratio in solar neutrino detection.     

Air-stable all-inorganic nanocrystal solar cells processed from solution

We introduce an ultrathin donor-acceptor solar cell composed entirely of inorganic nanocrystals spin-cast from solution. These devices are stable in air, and post-fabrication processing allows for power conversion efficiencies approaching 3% in initial tests. This demonstration elucidates a class of photovoltaic devices with potential for stable, low-cost power generation.     

胡萝卜高产栽培技术

胡萝卜是伞形科胡萝卜属,两年生双子叶植物。胡萝卜中含有蔗糖、葡萄糖、淀粉以及多量的胡萝卜素,是营养丰富的半耐寒性蔬菜。胡萝卜叶是饲养家畜家禽的优质饲草(料)。胡萝卜适应性强,病虫害少,便于贮藏、运输、供应期长。     

水芹高产高效浅水栽培技术

针对低洼水田和中低产田改造，总结出浅水种植水芹，高产高效栽培技术。     

现代高效农业规划机制探讨

农业规划具有前瞻性、指导性、可操作性等特点,以本项目组承担的具有江苏区域特色的江苏悦达·家乐福(建湖)现代农业示范区规划和苏州金庭大成现代农业园建设规划2个实例为实践蓝本,因地制宜,在综合考虑区域社会经济现状、农业特色、资源禀赋等情况的基础上,分析现代高效农业规划的目的意义,概括编制现代农业规划的基本路线,提出切合实际、高标准、高层次的农业功能定位,从而总结推动现代高效农业规划的措施和建议,为规划决策者和管理部门提供参考。     

大功率高效无干扰充电器研制

从理论上提出了电感限流充电方式,并求解了各种电流模式的微分方程,由此设计了一种B超专用UPS充电器,该机在实际中使用取得了理想的结果。     

Efficient tandem polymer solar cells fabricated by all-solution processing

Tandem solar cells, in which two solar cells with different absorption characteristics are linked to use a wider range of the solar spectrum, were fabricated with each layer processed from solution with the use of bulk heterojunction materials comprising semiconducting polymers and fullerene derivatives. A transparent titanium oxide (TiO(x)) layer separates and connects the front cell and the back cell. The TiO(x) layer serves as an electron transport and collecting layer for the first cell and as a stable foundation that enables the fabrication of the second cell to complete the tandem cell architecture. We use an inverted structure with the low band-gap polymer-fullerene composite as the charge-separating layer in the front cell and the high band-gap polymer composite as that in the back cell. Power-conversion efficiencies of more than 6% were achieved at illuminations of 200 milliwatts per square centimeter.     

大蒜覆膜高效栽培技术

随着农业结构的调整,大蒜近年来种植面积越来越大,2006年我们在平安镇各村进行试验示范,结果表明:666.7m2产量2000-2500kg,产值4000-5000元,在同等条件下,覆膜栽培666.7m2平均增产450kg,同时还可提前10-15天上市,1种子选择选用具有高产优质、适应性强的新疆“紫皮大蒜”,挑蒜瓣     

鄂西南地区山药高效优质栽培技术

鄂西南地区山药的高效优质栽培 ,必须抓好品种选择、健身栽培、病虫害防治、适时采收 4个环节。     

基于马氏距离的太阳能电池可靠性筛选方法研究

通过测量太阳能电池的内部低频噪声,可以快速、无损地实现太阳能电池的可靠性筛选分类。提出基于马氏距离的筛选方法分析噪声数据,进而得到全频段的噪声筛选判据。实验结果表明,本文方法和基于个别频率点的噪声分类方法相比,马氏距离筛选方法更加全面地反映了太阳能电池的整体低频噪声水平,不仅可以剔除1/f噪声大的太阳能电池,还可以剔除G-R(genera-tion-recombination)噪声和爆裂噪声大的太阳能电池,因此能将一批太阳能电池进行更为准确、精细的可靠性分类。     

浅水池塘高产养殖技术研究

水深1.2～1.3 m的浅水鱼池,在无机械增氧与人工加注新水的条件下,运用施肥、投饵、生石灰浆全池泼洒改善水质、轮捕等综合技术,获得单产7 038 kg/hm2,净产5 404.5 kg/hm2,盈利16 447.5元/hm2,投入产出比为1∶1 .9.     

设施农业与中国高效农业建设

针对现阶段我国农业发展面临的人口增加、人均占有资源数量减少、资源利用率低下、农业环境恶化、农民收入下降等问题,认为设施农业是实现我国农业高产高效的重要途径。设施农业在我国迅速兴起及其所展示出的巨大成效,证实设施农业必将成为人多地少的我国农业高效发展的重要选择,也可望成为世界农业发展的主要趋势。