964 research outputs found

    Organizational Paradoxes and Metamorphosis in Collective Action

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    This paper addresses the subject of organizational paradoxes through the lens of complexity theory. The first part of the study focuses on the formalization of the key elements in order to better understand the concept of organizational tension through the presentation of related constructs, i.e., dilemmas, dialectics and paradoxes. The second part of the paper introduces the key to interpreting complexity theory, highlighting how the characteristic of emergence in complex systems makes it possible to identify two different levels: that of organizational elements and that of organizational forms, both of which are impacted by tension. That reflection leads the authors to postulate that metamorphosis is the process by which organizations, constantly crossed by tension, regenerate the organizational forms’ level on the basis of evolving tensions between organizational elements

    Growth, ion content and photosynthetic responses of two Elytrigia Desv. species seedlings to salinity stress

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    Salinity is among the major abiotic stresses limiting crop production in the world. Elytrigia species, the wild relatives of wheat, are extensively used as genetic resources in wheat breeding to improve its salt tolerance. The objective of this study was to examine the responses to different NaCl treatments (0, 65, 100, 135 and 170 mM) of two Elytrigia species (Elytrigia intermedia (Host.) Nevski. and Elytrigia trichophora (Link.) Nevski.) in terms of their growth, ion content and photosynthetic productivity during the seedling stages. For E. intermedia, salt treatment led to decreases in root and shoot biomass, chlorophyll content, photosynthetic rate (A) and stomatal conductance (gs), and a concurrent increase in intercellular CO2 concentration (Ci). Larger reductions in the parameters occurred in E. trichophora. Our results indicated that the two species differ in their sensitivity to salinity, with E. intermedia being classified as the more salt tolerant, and E. trichophora as sensitive. The two species also differed noticeably in leaf tissue concentrations of Na+ and K+ at various NaCl treatments, although, they both showed a trend for Na+ content to increase and K+ accumulation to significantly decrease in the higher salinity treatments.Key words: Elytrigia, ion contents, photosynthesis, salinity

    Growth and physiological response of tall oat grass to salinity stress

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    In order to evaluate the responses of tall oat grass plants to increasing salinity, we measured plant growth, ion contents, photosynthetic gas exchange, lipid peroxidation, and proline accumulation in four salt concentrations. Two tall oatgrass genotypes, ZXY03P-367 and ZXY03P-443, were grown for 14 days in greenhouse conditions and after 14 days treated with four NaCl treatments (0, 65, 100, and 135 mM ) for 21 days. Most parameters for the two genotypes were significantly different when they were subjected to 100 and 135 mM NaCl. Salt treatment led to decreases in root and shoot biomass, photosynthetic rate (A) and stomatal conductance (gs), and K+ content, and a concurrent increase in Na+ content. Larger reductions in the parameters occurred in ZXY03P-443. A significant accumulation of lipid peroxidation and proline in leaves was found during the period of intensive leaf growth. These organic compounds likely played a role in leaf osmotic adjustment and in the protection of membrane stability at severe salinity levels. Our results indicated that the two tall oatgrass genotypes differ in their sensitivity to salinity, with ZXY03P-336 classified as relatively salt tolerant and ZXY03P-443 as  sensitive.Key words: Growth, physiological responses, salinity stress, tall oatgras

    Superelastic Hybrid CNT/Graphene Fibers for Wearable Energy Storage

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    The demands for wearable technologies continue to grow and novel approaches for powering these devices are being enabled by the advent of new electromaterials and novel fabrication strategies. Herein, a novel approach is reported to develop superelastic wet-spun hybrid carbon nanotube graphene fibers followed by electrodeposition of polyaniline to achieve a high-performance fiber-based supercapacitor. It is found that the specific capacitance of hybrid carbon nanotube (CNT)/graphene fiber is enhanced up to ≈39% using a graphene to CNT fiber ratio of 1:3. Fabrication of spring-like coiled fiber coated with an elastic polymer shows an extraordinary elasticity capable of 800% strain while affording a specific capacitance of ≈138 F g -1 . The elastic rubber coating enables extreme stretchability and enabling cycles with up to 500% strain for thousands of cycles with no significant change in its performance. Multiple supercapacitors can be easily assembled in series or parallel to meet specific energy and power needs

    A methodology for the assessment of experiential learning lean: The lean experience factory case study

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    Purpose \u2013 The purpose of this paper is to present a methodology to assess the experiential learning processes of learning lean in an innovative learning environment: the lean model factories. Design/methodology/approach \u2013 A literature review on learning and lean management literatures was carried out to design the methodology. Then, a case study methodology was used to test the framework. Findings \u2013 The methodology permitted to asses learning processes and course contents of educational dynamics carried out in model factories and to theoretically ground such learning processes. The test showed that learning lean management is supported through a complete coverage of the eight phases of the learning path. Research limitations/implications \u2013 The methodology contributes to the literatures of lean management and experiential learning, proposing a methodology of assessment. Part of the framework could also be applied to other disciplines. Practical implications \u2013 The methodology could be used for two purposes: to design training courses or to assess existing experiential learning courses. Originality/value \u2013 Due to its intrinsic complexity, learning literature presents few practical framework or tools. Among them, none have provided practical and theoretical-based advice on how to use experiential learning precepts to teach lean managemen

    Crystal structure of Li_2B_(12)H_(12): a possible intermediate species in the decomposition of LiBH_4

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    The crystal structure of solvent-free Li_2B_(12)H_(12) has been determined by powder X-ray diffraction and confirmed by a combination of neutron vibrational spectroscopy and first-principles calculations. This compound is a possible intermediate in the dehydrogenation of LiBH_4, and its structural characterization is crucial for understanding the decomposition and regeneration of LiBH_4. Our results reveal that the structure of Li_2B_(12)H_(12) differs from other known alkali-metal (K, Rb, and Cs) derivatives

    Using agronomic biofortification to boost zinc, selenium, and iodine concentrations of food crops grown on the loess plateau in China

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    Micronutrient malnutrition among humans is typically caused by micronutrient deficiency in soils and then staple food crops grown on these soils. In this study, field trials were conducted to investigate the biofortification of micronutrients in the edible parts of winter wheat, maize, soybean, potato, canola, and cabbage. Fertilizers of Se, Zn and I were applied to soil independently or together, while Se and Zn were sprayed as solution on winter wheat in another part of the trials. Selenium, when applied to the soil in the form of sodium selenate, whether alone or combined with Zn and⁄or I, was effective in increasing Se to around target levels in all of the tested crops. Selenium as sodium selenite was effective as a foliar application to winter wheat, increasing it from 25 to 312 ”g kg⁻Âč in wheat grain with 60 g Se ha⁻Âč . For Zn, soil-applied zinc sulphate was only found to be effective for increasing the Zn concentration in cabbage leaf and canola seed, with 35 and 61 mg kg ⁻Âč, respectively, while foliar zinc sulphate application was effective in biofortifying winter wheat, increasing grain Zn from 20 to 30 mg kg⁻Âč . While for I, soil-applied potassium iodate was only effective in increasing I concentration in cabbage leaf, and biofortification of the other crops was not possible. The enhancements of Se, Zn, and I concentration resulting from either the single or combined application of microelement fertilizers were similar. Therefore, agronomic biofortification of edible parts of various food crops with Zn, Se, and I can be an effective way to increase micronutrient concentrations, and the effectiveness depends on crop species, fertilizer forms and application methods.H. Mao, J. Wang, Z. Wang, Y. Zan, G. Lyons, C. Zo

    LiSc(BH_4)_4 as a Hydrogen Storage Material: Multinuclear High-Resolution Solid-State NMR and First-Principles Density Functional Theory Studies

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    A lithium salt of anionic scandium tetraborohydride complex, LiSc(BH_4)_4, was studied both experimentally and theoretically as a potential hydrogen storage medium. Ball milling mixtures of LiBH_4 and ScCl_3 produced LiCl and a unique crystalline hydride, which has been unequivocally identified via multinuclear solid-state nuclear magnetic resonance (NMR) to be LiSc(BH_4)_4. Under the present reaction conditions, there was no evidence for the formation of binary Sc(BH_4)_3. These observations are in agreement with our first-principles calculations of the relative stabilities of these phases. A tetragonal structure in space group I (#82) is predicted to be the lowest energy state for LiSc(BH_4)_4, which does not correspond to structures obtained to date on the crystalline ternary borohydride phases made by ball milling. Perhaps reaction conditions are resulting in formation of other polymorphs, which should be investigated in future studies via neutron scattering on deuterides. Hydrogen desorption while heating these Li−Sc−B−H materials up to 400 °C yielded only amorphous phases (besides the virtually unchanged LiCl) that were determined by NMR to be primarily ScB_2 and [B_(12)H_(12)]^(−2) anion containing (e.g., Li_2B_(12)H_(12)) along with residual LiBH_4. Reaction of a desorbed LiSc(BH_4)_4 + 4LiCl mixture (from 4LiBH_4/ScCl_3 sample) with hydrogen gas at 70 bar resulted only in an increase in the contents of Li_2B_(12)H_(12) and LiBH_4. Full reversibility to reform the LiSc(BH_4)_4 was not found. Overall, the Li−Sc−B−H system is not a favorable candidate for hydrogen storage applications

    Study of aluminoborane compound AlB_4H_(11) for hydrogen storage

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    Aluminoborane compounds AlB_4H_(11), AlB_5H_(12), and AlB_6H_(13) were reported by Himpsl and Bond in 1981, but they have eluded the attention of the worldwide hydrogen storage research community for more than a quarter of a century. These aluminoborane compounds have very attractive properties for hydrogen storage: high hydrogen capacity (i.e., 13.5, 12.9, and 12.4 wt % H, respectively) and attractive hydrogen desorption temperature (i.e., AlB_4H_(11) decomposes at ~125 °C). We have synthesized AlB_4H_(11) and studied its thermal desorption behavior using temperature-programmed desorption with mass spectrometry, gas volumetric (Sieverts) measurement, infrared (IR) spectroscopy, and solid state nuclear magnetic resonance (NMR). Rehydrogenation of hydrogen-desorbed products was performed and encouraging evidence of at least partial reversibility for hydrogenation at relatively mild conditions is observed. Our chemical analysis indicates that the formula for the compound is closer to AlB_4H_(12) than AlB_4H_(11)

    A first assessment of genetic variability in the longhorn beetle Rosalia alpina (Coleoptera: Cerambycidae) from the Italian Apennines

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    The Rosalia longicorn (Rosalia alpina) is a strictly protected saproxylic beetle, widely distributed in Central and Southern Europe and mainly associated with ancient beech forests. To improve knowledge about the conservation status of R. alpina in Italy, available molecular markers (microsatellites and mitochondrial cytochrome c oxidase I(COI)) were tested for the first time on Italian populations. The study was performed in four sampling sites distributed in two areas placed in Northern (“Foreste Casentinesi” National Park) and Central Apennines (“Abruzzo, Lazio and Molise” National Park) where populational data about Rosalia longicorn were collected in the framework of the European LIFE MIPP Project. The genetic relationship among Apennine and Central/South-eastern European populations was explored by a comparison with mitochondrial DNA (mtDNA) data from literature. Microsatellite markers were only partially informative when applied to R. alpina Italian individuals, although providing some preliminary indication on an extensive gene flow among populations from the Apennines and local ongoing processes of genetic erosion. Genetic data are consistent with previous ecological data suggesting that the maintenance of variability in this species could be related to both habitat continuity and preservation of large senescent or standing dead trees in forests. Finally, a peculiar origin of the Apennine populations of R. alpina from a putative “Glacial Refugium” in Italy was inferred through COI data. The high genetic distance scored among the analysed populations and those from Central and South-eastern Europe indicates that the R. alpina deme from Apennine Mountains might represent a relevant conservation unit in Europe. Further genetic analyses will allow assessing other possible conservation units of R. alpina and, thus, defining large-scale conservation strategies to protect this endangered longhorn beetle in Europe
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