5,738 research outputs found

    Solid-liquid equilibria for nitrous oxide+ fluoromethane and triple point measurements for refrigerants

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    To evaluate the Solid-Liquid Equilibria (SLE) of alternative refrigerants systems, an experimental set-up was employed. The behaviour of the nitrous oxide + fluoromethane (N2O + R41) binary system was measured down to temperatures of 126.5 K. The triple point temperature of carbon dioxide, nitrous oxide and of seven of the most widely applied alternative refrigerants, namely fluoromethane (R41), difluoromethane (R32), trifluoromethane (R23), pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a) and 1,1-difluoroethane (R152a), were also measured. All triple point data measured revealed a generally good consistency with the literature. The results obtained for the mixtures were corrected by the Rossini method and interpreted by means of the Schröder equation. © 2012 Old City Publishing, Inc

    Axial eccentric SynRel and SPM Motors analytical models validation using 3D finite element

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    This paper deals with the uniform and non-uniform axial eccentricity analyses of the surface mounted permanent magnet and synchronous reluctance machines. The analyses are carried out using an analytical model for each considered machine. Being the axial eccentricity a 3D physical phenomenon, the standard sliding approach used in the analytical models has been validated through accurate 3D FE simulations. The results presented in this paper verify the effectiveness of the analytical approaches quantifying the results deviations respect to the computational expensive 3D FE simulations. The results also confirms that synchronous reluctance machines show higher radial forces compared to the surface permanent magnet machines for the same eccentricity level, main geometry and operating condition

    An experimental multiprocessor system for distributed parallel computations.

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    The availability of low-cost microprocessor chips with efficient instruction sets for specific numerical tasks (signal processors) has been exploited for building a versatile multiprocessor system, consisting of a host minicomputer augmented by a number of joint processors. The host provides a multiuser-multitasking environment and manages system resources and task scheduling. User applications can call upon one or more joint processors for parallel execution of adequately partitioned, computationally intensive numeric operations. Each joint processor has sufficient local memory for storing procedures and data and has access to regions in host memory for shared data. Kernel processes in the host and in the joint processors provide the necessary mechanism for initialization and synchronization of the distributed parallel execution of procedures

    Spontaneous self-assembly of an unsymmetric trinuclear triangular copper(II) pyrazolate complex, [Cu3(μ3-OH)(μ-pz) 3(MeCOO)2(Hpz)] (Hpz = pyrazole). Synthesis, experimental and theoretical characterization, reactivity, and catalytic activity

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    The almost quantitative formation of the triangular trinuclear copper derivative [Cu3(μ3-OH)(μ-pz)3(MeCOO) 2(Hpz)] (1) (Hpz = pyrazole), has been simply achieved by adding Hpz to an ethanol solution of Cu(MeCOO)2·H2O. An X-ray molecular structure determination shows that 1 is completely unsymmetric and that trinuclear units result assembled in an extended bidimensional network formed through acetate bridges and hydrogen bonds. EPR and magnetic measurements are consistent with the presence of a single unpaired electron. Theoretical density functional calculations carried out for S = 1/2 provide a thorough description of the electronic structure of 1, allowing a detailed assignment of its UV-vis absorption spectrum. Compound 1 reacts with MeONa, yielding [Cu 3(μ3-OH)(μ-pz)3(MeCOO)(MeO)(Hpz)] (2) and [Cu3(μ3-OH)(μ-pz)3(MeO) 2(Hpz)] (3) through the substitution of one and two acetate ions, respectively, with MeO- ion(sS). The spontaneous self-assembly of the triangular trinuclear Cu3 moiety seems to occur only with pyrazole as can be inferred by the results obtained in the reactions of copper(II) acetate with some substituted pyrazoles leading to the formation of mononuclear [Cu(MeCOO)2(L)2] (4-8) and dinuclear [Cu(MeCOO) 2(L)]2 (9-11) (L = substituted pyrazole) compounds. Also the presence of acetate ions seems to play a leading role in determining the formation of the trinuclear triangular arrangement, as indicated by the formation of a mononuclear derivative, [Cu(CF3COO) 2(Hpz)]2 (compound 12), in the reaction of copper(II) trifluoroacetate with pyrazole. Compounds 1-3, as well as some other mono- and dinuclear copper(II)-substituted pyrazole complexes, have been tested as catalyst precursors in cyclopropanation reaction, observing the formation of products in a syn:anti ratio opposite that normally reported

    Effects of irrigation treatments on the quality of table olives produced with the Greek-style process

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    The irrigation of olive orchards is commonly applied to produce table olives with optimal size. No data have been published on the microbiological quality of drupes from irrigated olive groves during fermentation. The trials T100 and T50 (receiving a water amount equivalent to 100 % and 50 % of the required, respectively) and the control T0 (rainfed trial) were monitored during two consecutive years. Results showed significant increase of equatorial diameter and flesh:pit ratio of irrigated drupes. The decrease of pH and the numbers of lactic acid bacteria (LAB) registered for the irrigated trials during the fermentation were more consistent than those displayed by control T0. Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus coryniformis and Pediococcus pentosaceous for LAB, and Candida boidinii, Candida diddensiae and Wickerhamomyces anomalus for yeasts were isolated at highest concentrations. The global sensory acceptance was better for irrigated trials rather than control T0. The statistical multivariate analysis showed that the effect of irrigation was independent from the seasonal variability and it clearly distinguished the T100 and T50 trials from rainfed control. The irrigation improve significantly the quality of table olives. Interestingly, all explorative multivariate analyses showed low dissimilarity between irrigated trials; thus the thesis T50 represents an effective approach to save water in olive orchards without compromising the quality of table olives

    Potential Impact of Microplastics and Additives on the Health Status of Loggerhead Turtles (Caretta caretta) Stranded Along the Central Adriatic Coast

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    AbstractLoggerhead sea turtle (C. caretta) is the official European bioindicator of marine litter in the Mediterranean Sea. In 2019, 8 sea turtles, out of 28 specimens loggerhead on the Adriatic coast of Molise, were subjected to necropsy. The intestinal contents were collected and the microplastics until 0.45 μm were extracted. Qualitative and quantitative assessments were performed by stereomicroscope observation and spectroscopic analyses (attenuated total reflection-Fourier transform infrared spectroscopy, ATR-FTIR and Raman microspectroscopy, RMS). Moreover, the analytical quantification of polyethylene terephthalate (PET), polycarbonate (PC), para phthalic acid (PTA) and bisphenol A (BPA) in fat and liver tissues was performed by LC-MS/MS. Microparticles ranging from 0.45 μm to 1 mm were found in all turtles, for a total of 623, while plastic litter greater than 1 mm were found only in 4 specimens (ranging from 0.03 to 0.11 g). Nineteen different polymers and 10 pigments, including polyester (100% of animals), high-density polyethylene (50%) and polypropylene (50%) were identified. BPA, PTA and PET were detected in fat and liver tissues of all animals, while PC was found only in 50%. A major prevalence was registered in the abdominal fat tissue, although only PC compounds were significantly higher in abdominal tissue (p < 0.05), except for free PTA with liver tissue being the most contaminated (p < 0.05). Microplastics and additives surely impact the health status of turtles that showed gastrointestinal impairment and an important level of contamination in tissues. Graphical abstrac
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