2,184 research outputs found

    The speed of sound and isentropic compressibility of liquid difluoromethane (HFC32) fromT=(248 to 343) K and pressures up to 65 MPa

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    This work reports experimental data on the speed of sound in liquid difluoromethane ŽHFC32, or R32. from T s Ž248 to 343. K and pressures up to 65 MPa. The results were obtained using a newly-built apparatus, calibrated with toluene over the whole experimental region, and show good agreement with two available data sets. The uncertainties are "0.01 K in the temperature, "0.025 MPa in the pressure up to 35 MPa, and "0.2 MPa above this value. The final uncertainty on the speed of sound is estimated to be "0.2 per cent. The data were fitted using a simple analytical equation and the results are discussed. The isentropic compressibility was calculated over the Ž p, T. surface where the reported speed of sound values and the corresponding literature densities overlap.info:eu-repo/semantics/publishedVersio

    The speed of sound, and derived thermodynamic properties of liquid trifluoromethane (HFC23) fromT=(258 to 303)K at pressures up to 65MPa

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    This work reports experimental data of the speed of sound in liquid trifluoromethane (HFC23, or R23) from T = (258 to 303) K at pressures up to 65 MPa, measured with a pulse-echo method adapted from Papadakis(1) and Guedes et al.(2) The results are fitted to a rational approximant and compared with literature data.(3) Derived thermodynamic properties such as the isentropic compressibility κs, the isothermal compressibility κT , the cubic expansion coefficient αp, and the specific heat capacity at constant pressure cp are calculated by combining the present experimental data with the density values published by other authors.(4–11) The estimated properties are compared, where possible, with literature data.info:eu-repo/semantics/publishedVersio

    Descrição botânica e técnicas da polinização controlada do gergelim (Sesamum indicum L).

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    Ultrasonic speed of sound and derived thermodynamic properties of liquid 1, 1, 1, 2, 3, 3, 3-heptafluoropropane (HFC227ea) from 248 K to 333 K and pressures up to 65 MPa

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    This work reports experimental data of the speed of sound in liquid 1,1,1,2,3,3,3-heptafluoropropane (HFC227ea) from 248 K to 333 K and pressures up to 65 MPa, measured with a pulse-echo method. The results are fitted with a rational approximant. Derived thermodynamic properties are calculated, combining our experimental data with density and isobaric heat capacity values published by other authors. The results were compared with the data available in the literature.info:eu-repo/semantics/publishedVersio

    Características físicas e nutricionais da matriz de encapsulamento na produção de sementes sintéticas de pimenta-longa (Piper hispidinervum C. DC.).

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    A pimenta-longa (Piper hispidinervum C. DC.) é um arbusto da família Piperaceae, nativa da região amazônica, que vem despertando o interesse das indústrias de cosméticos e bioinseticidas pelo alto teor de safrol, óleo essencial extraído das folhas e talos. O objetivo do trabalho foi avaliar a influência de características físicas e nutricionais da matriz de encapsulamento durante a produção de sementes sintéticas de pimenta-longa. Sementes germinadas de pimenta-longa foram utilizadas como material de encapsulamento. Em ambos os experimentos, a influência da constituição (água ou meio Murashige e Skoog) e consistência da cápsula (alginato de sódio 1% ou 2%) e do tempo de complexação (10, 20 e 30 min) em CaCl2, na abertura das cápsulas, foi avaliada. Depois de encapsulados, os materiais foram transferidos para frascos com meio de MS e mantidos em sala de crescimento, onde, quinzenalmente, foi avaliada a taxa de emergência e crescimento das plântulas encapsuladas. Verificou-se que o emprego de um endosperma artificial composto por 1% de alginato de sódio em meio de MS foi o tratamento que promoveu os melhores resultados para a emergência e posterior crescimento de plântulas oriundas de sementes sintéticas aos 30 dias da semeadura em meio MS sólido, independentemente do tempo de complexação utilizado

    Uterine artery Doppler in the management of early pregnancy loss: a prospective, longitudinal study

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    The pharmacological management of early pregnancy loss reduced substantially the need for dilation and curettage. However, prognostic markers of successful outcome were not established. Thus the major purpose of this study was to determine the sensitivity and specificity of the uterine artery pulsatility (PI) and resistance (RI) indices to detect early pregnancy loss patients requiring dilation and curettage after unsuccessful management

    Internal iliac and uterine arteries Doppler ultrasound in the assessment of normotensive and chronic hypertensive pregnant women

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    The objective of this work was to compare Doppler flows pulsatility index (PI) and resistance indexes (RI) of uterine and internal iliac arteries during pregnancy in low risk women and in those with stage-1 essential hypertension. From January 2010 and December 2012, a longitudinal and prospective study was carried out in 103 singleton uneventful pregnancies (72 low-risk pregnancies and 31 with stage 1 essential hypertension)at the 1(st), 2(nd) and 3(rd) trimesters. Multiple linear regression models, fitted using generalized least squares and whose errors were allowed to be correlated and/or have unequal variances, were employed; a model for the relative differences of both arteries impedance was utilized. In both groups, uterine artery PI and RI exhibited a gestational age related decreasing trend whereas internal iliac artery PI and RI increased. The model testing the hemodynamic adaptation in women with and without hypertension showed similar trend. Irrespective of blood pressure conditions, the internal iliac artery resistance pattern contrasts with the capacitance pattern of its immediate pelvic division, suggesting a pregnancy-related regulatory mechanism in the pelvic circulation
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