One basic problem is the unconcentrated energy content of sunlight.
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Ypadú or ypadu is an unrefined, unconcentrated powder made from coca leaves and the ash of various other plants. Like coca teas consumed in Peru to adapt to sickness induced by high elevation, it has a long ethnobotanical history and cultural associations.
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In Canada, tomato juice is unconcentrated and pasteurized, made from fine tomato pulp from ripe and whole tomatoes. The stems and skins must be removed without adding water to the final juice product. It may also contain a sweetening agent, citric acid and salt.
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This adaptation causes foragers to harvest resources with low concentrations of sucrose that include water, pollen, and unconcentrated nectar. A study comparing A. m. scutellata and A. m. ligustica published by Fewell and Bertram in 2002 suggests that the differential evolution of this suite of behaviors is due to the different environmental pressures experienced by African and European subspecies.
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The Shockley-Queisser limit for the efficiency of a single-junction solar cell. It is essentially impossible for a single-junction solar cell, under unconcentrated sunlight, to have more than ~34% efficiency. A multi-junction cell, however, can exceed that limit. The theoretical performance of a solar cell was first studied in depth in the 1960s, and is today known as the Shockley–Queisser limit.
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A representative example is copper indium gallium selenide (CuInxGa(1–x)Se2, Eg = 1.7–1.0 eV for x = 0–1), which is used in copper indium gallium selenide solar cells. Optical absorption spectrum of β-CuGaO2 powder (top left inset) obtained from diffuse reflection measurements. The right inset shows the Shockley-Queisser limit for the efficiency of a single-junction solar cell under unconcentrated sunlight.
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The Shockley-Queisser limit for the efficiency of a single-junction solar cell under unconcentrated sunlight. This calculated curve uses actual solar spectrum data, and therefore the curve is wiggly from IR absorption bands in the atmosphere. This efficiency limit of about 34% can be exceeded by multijunction solar cells. Excitonic solar cells generates free charge by bound and intermediate exciton states unlike inorganic and crystalline solar cells.
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Carrier multiplication facilitates multiple electron-hole pair generation for each photon absorbed. Efficiency limits for photovoltaic cells can be theoretically higher considering thermodynamic effects. For a solar cell powered by the Sun's unconcentrated black-body radiation, the theoretical maximum efficiency is 43% whereas for a solar cell powered by the Sun's full concentrated radiation, the efficiency limit is up to 85%. These high values of efficiencies are possible only when the solar cells use radiative recombination and carrier multiplication.
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Examination of cells in body fluids was historically performed using a hemocytometer, a chamber designed for counting cells microscopically. This technique was limited by poor discrimination between cell types (cells could only be classified as mononuclear or polymorphonuclear) and the low number of cells present in unconcentrated body fluids. Moreover, this technique did not produce a permanent record of the specimen. In a 1966 paper, Watson P. described the first cytocentrifuge, calling it "an apparatus for concentrating cells in suspension onto a microscope slide".
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Extra jam is subject to somewhat stricter rules that set higher standards for the minimum fruit content (45% instead of 35% as a general rule, but lower for some fruits such as redcurrants and blackcurrants), as well specifying as the use of unconcentrated fruit pulp, and forbidding the mixture of certain fruits and vegetables with others. Extra jelly similarly specifies that the quantity of fruit juice or aqueous extracts used to make 1,000 grams of finished product must not be less than that laid down for the manufacture of extra jam.
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Mass wasting in coastal Alaska Colluvium (also colluvial material or colluvial soil) is a general name for loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rainwash, sheetwash, slow continuous downslope creep, or a variable combination of these processes. Colluvium is typically composed of a heterogeneous range of rock types and sediments ranging from silt to rock fragments of various sizes. This term is also used to specifically refer to sediment deposited at the base of a hillslope by unconcentrated surface runoff or sheet erosion.
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The limit is one of the most fundamental to solar energy production with photovoltaic cells, and is considered to be one of the most important contributions in the field. The limit is that the maximum solar conversion efficiency is around 33.7% for a single p-n junction photovoltaic cell, assuming typical sunlight conditions (unconcentrated, AM 1.5 solar spectrum), and subject to other caveats and assumptions discussed below. This maximum occurs at a band gap of 1.34 eV. That is, of all the power contained in sunlight (about 1000 W/m2) falling on an ideal solar cell, only 33.7% of that could ever be turned into electricity (337 W/m2).
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