2,483 research outputs found

    Heat and fluid flow in a scraped-surface heat exchanger containing a fluid with temperature-dependent viscosity

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    Scraped-surface heat exchangers (SSHEs) are extensively used in a wide variety of industrial settings where the continuous processing of fluids and fluid-like materials is involved. The steady non-isothermal flow of a Newtonian fluid with temperature-dependent viscosity in a narrow-gap SSHE when a constant temperature difference is imposed across the gap between the rotor and the stator is investigated. The mathematical model is formulated and the exact analytical solutions for the heat and fluid flow of a fluid with a general dependence of viscosity on temperature for a general blade shape are obtained. These solutions are then presented for the specific case of an exponential dependence of viscosity on temperature. Asymptotic methods are employed to investigate the behaviour of the solutions in several special limiting geometries and in the limits of weak and strong thermoviscosity. In particular, in the limit of strong thermoviscosity (i.e., strong heating or cooling and/or strong dependence of viscosity on temperature) the transverse and axial velocities become uniform in the bulk of the flow with boundary layers forming either just below the blade and just below the stationary upper wall or just above the blade and just above the moving lower wall. Results are presented for the most realistic case of a linear blade which illustrate the effect of varying the thermoviscosity of the fluid and the geometry of the SSHE on the flow

    Mapping Patent Classifications: Portfolio and Statistical Analysis, and the Comparison of Strengths and Weaknesses

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    The Cooperative Patent Classifications (CPC) jointly developed by the European and US Patent Offices provide a new basis for mapping and portfolio analysis. This update provides an occasion for rethinking the parameter choices. The new maps are significantly different from previous ones, although this may not always be obvious on visual inspection. Since these maps are statistical constructs based on index terms, their quality--as different from utility--can only be controlled discursively. We provide nested maps online and a routine for portfolio overlays and further statistical analysis. We add a new tool for "difference maps" which is illustrated by comparing the portfolios of patents granted to Novartis and MSD in 2016.Comment: Scientometrics 112(3) (2017) 1573-1591; http://link.springer.com/article/10.1007/s11192-017-2449-

    Hemorrhagic Shock Caused by Rupture of an Intra-Abdominal Leydig Cell Tumour: Case Report

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    The rupture of an intra-abdominal testicular neoplasm is a rare cause of acute abdomen and massive intra-abdominal haemorrhage. We report the case of a 70-year-old male presenting a massive intra-abdominal bleeding caused by a Leydig cell tumour in an undescended testis. The clinical details and pathology of this rare testicular tumour are discussed

    Influence of the initial chemical conditions on the rational design of silica particles

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    The influence of the water content in the initial composition on the size of silica particles produced using the Stöber process is well known. We have shown that there are three morphological regimes defined by compositional boundaries. At low water levels (below stoichiometric ratio of water:tetraethoxysilane), very high surface area and aggregated structures are formed; at high water content (>40 wt%) similar structures are also seen. Between these two boundary conditions, discrete particles are formed whose size are dictated by the water content. Within the compositional regime that enables the classical Stöber silica, the structural evolution shows a more rapid attainment of final particle size than the rate of formation of silica supporting the monomer addition hypothesis. The clearer understanding of the role of the initial composition on the output of this synthesis method will be of considerable use for the establishment of reliable reproducible silica production for future industrial adoption

    Transgenic Bt Cotton

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    Not AvailableCotton is one of the major fibre crops of global significance. It is cultivated in tropical and subtropical regions of more than eighty countries of world occupying nearly 33 m ha with an annual production of 19 to 20 million tones of bales. China, U.S.A., India, Pakistan, Uzbekistan, Australia, Brazil, Greece, Argentina and Egypt are major cotton producing countries. These countries contribute nearly 85% of the global cotton production. In India, cotton is being cultivated in 9.0 m ha and stands first in acreage. The crop is grown in varied agro-climatic situation across nine major states viz. Maharashtra, Gujarat, Madhya Pradesh, Punjab, Haryana, Rajasthan, Andhra Pradesh, Karnataka and Tamil Nadu. The crop is also grown on small area in Orissia, Assam, U.P and West Bengal. Nearly 60 million people are engaged in cotton production, marketing and processing. The textile industry which utilizes the cotton provides employment to about 16% of the total workforce. Cotton in its various forms also serves as raw material for more than 25 industries

    Direct valorization of cellulose and glucose to glycolic acid through green catalytic process

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    The current work reports the catalytic conversion of α-cellulose to glycolic acid using molecular oxygen as an oxidant. A series of copper and cobalt molybdophosphoric acid catalysts (Cu-H3PMo12O40 and Co-H3PMo12O40) were synthesized via impregnation and ion-exchange techniques. Then the synthesized catalysts are thoroughly tested for effective conversion of α-cellulose and glucose into glycolic acid and value-added chemicals. The physicochemical characterization of as prepared catalysts was carried out using X-ray diffraction (XRD) and a scanning electron microscope-energy dispersive spectrometer (SEM–EDS). Fourier-transform infrared spectroscopy (FT-IR), N2-Physisorption and the Hammett test, on the other hand, were used to determine the quantitative relationship between catalyst structure and catalyst activity. Under mild reaction conditions, glycolic acid was discovered to be the primary product with 99.8% selectivity and 99% yield over a Cu-impregnated H3PMo12O40 catalyst. It was also revealed that the catalytic activity was directly related to the catalyst surface area, degree of crystallization, and surface acidic strength. Moreover, synergic interactions of active metals with support materials, Bronsted and Lewis acid properties possessed by catalysts are major determinants of better catalytic activity. Graphic Abstract: (Figure presented.)
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