617 research outputs found

    A physical model for downward burning

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    Elementary physical model for flammable materials combustion emphasizing downward burnin

    Intermittent immersion vessel apparatus and process for plant propagation

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    A plant micropropagation apparatus and process is provided in which a support platform for vessels containing a liquid growth media are periodically pivoted which brings about an intermittent immersion of the plant tissue/growth substrate in the growth media. The motion of the support platform may optionally be used to engage a piston operated dispenser for supplying aseptic media to the sealed vessel. The intermittent immersion also provides for an improved method of separating viable embryos from culture materials using a separation matrix in conjunction with the intermittent wave motion of the plant media when suspended in a liquid culture

    Approaching Mechanization of Plant Micropropagation

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    Investigations of materials and methods for growing plant tissue in a continual-flow, liquid nutrient medium as an alternative to semisolid agar medium have been made. Enhanced growth of plant tissue on microporouspolypropylene membranes floating on a liquid nutrient has been demonstrated. Moreover, in vitro plantlets on the microporous membrane are free from entanglement with the support matrix and readily available to mechanizedhandling. Trained growth of plantlets through polypropylene netting shows potential for mechanization by mass handling (separation, singulation, and transfer) of plant tissue cultures

    Mass Handling of Watermelon Microcuttings

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    Modifications were made in the configurations of the unitizing, nonselective wire cutters used by Alper et al.(1992) for mass cuttings of Stage II Citrullus lanatus cv. Charlee (watermelon) plant tissue cultures to further enhance productivity. Mounting the cutter in an inverted position over the receiving vessel eliminated time required for filling. This cut-and-dump technique became 4.8 times more productive for the total transfer process than the conventional scalpel and forceps technique when both time and yield of cut segments with visible buds were considered. A concept for growing fewer, larger tissue clusters per vessel in mini-trays with orienting cells and cutting with correspondingly sized orientedcell wire cutters yielded as much tissue fresh weight as conventional agar vessels and afforded the potential to reduce time required for the removal job function with the cut-and-dump technique

    A New Synthetic Amphidiploid in Cucumis from a C. sativus x C. hystrix F1 Interspecific Hybrid

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    CT. A synthetic amphidiploid was developed through organogenesis in tissue culturefrom an interspecific F1hybrid betweenCucumis sativus L. andC. hystrix Chakr. The resultsfrom flow cytometry indicated that, on average, 7.3% of the regenerants with unique morphology were chromosome-doubled F1hybrids. The 2C DNA content of the original F1hybrid was1.17 pg, and the 4C DNA content was 2.35 pg. Frequency of chromosome doubling between thetwo genotypes used in this study varied considerably

    Unitized, Nonselective Cutting of In Vitro Watermelon

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    Unitized, nonselective mass cutting of Stage II Citrullus lanatus cv. Charlee (watermelon) plant tissue cultures has been achieved with various configurations and sizes of wire cutter devices. Time studies revealed that the wire cutters increased the productivity of the cutting function over conventional scalpel and forceps by a factor of 14, Total transfer productivity, including the manual functions of removing tissue from an initial culture vessel and filling (sorting and placing cut tissue segments) new vessels, was increased by a factor of 1,8, The square grid-type cutting devices yielded from 48 to 59% as many viable bud clusters per culture vessel as hand cutting and from 65 to 95% as much tissue fresh weight. An oriented-cell configuration of wire cutter actually increased tissue fresh weight about 20% over hand cutting. The simplicity of construction and quality of material of the wire cutter render it readily autoclavable and highly flexible to function both as an aid to small operations and as an element in more sophisticated mechanical devices for larger operations

    Support for graphicacy: a review of textbooks available to accounting students

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    This Teaching Note reports on the support available in textbooks for graphicacy that will help students understand the complexities of graphical displays. Graphical displays play a significant role in financial reporting, and studies have found evidence of measurement distortion and selection bias. To understand the complexities of graphical displays, students need a sound understanding of graphicacy and support from the textbooks available to them to develop that understanding. The Teaching Note reports on a survey that examined the textbooks available to students attending two Scottish universities. The support of critical graphicacy skills was examined in conjunction with textbook characteristics. The survey, which was not restricted to textbooks designated as required reading, examined the textbooks for content on data measurement and graphical displays. The findings highlight a lack of support for graphicacy in the textbooks selected. The study concludes that accounting educators need to scrutinize more closely the selection of textbooks and calls for more extensive research into textbooks as a pedagogic tool

    Mononuclear phagocytes have the potential for sustained hydroxyl radical production. Use of spin-trapping techniques to investigate mononuclear phagocyte free radical production

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    Monocytes lack lactoferrin and have much less myeloperoxidase than neutrophils. They also acquire a potential catalyst for .OH production (tartrate-resistant acid phosphatase) as they differentiate into macrophages. Consequently, the nature of free radicals produced by these cells was examined using the previously developed spin-trapping system. When stimulated with either PMA or OZ neither monocytes nor monocyte-derived macrophages (MDM) exhibited spin trap evidence of .OH formation. Pretreatment with IFN-gamma failed to induce MDM .OH production. When provided with an exogenous Fe+3 catalyst, both stimulated monocytes and MDM, but not PMN, exhibited sustained .OH production, presumably due to the absence of lactoferrin in mononuclear phagocytes. Sustained production of .OH could contribute to the microbicidal activity of mononuclear phagocytes as well as inflammatory tissue damage under in vivo conditions where catalytic Fe+3 may be present
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