2,146 research outputs found

    Selecting Critical Properties of Terpenes and Terpenoids through Group-Contribution Methods and Equations of State

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    The knowledge of critical properties is fundamental in engineering process calculations for the estimation of thermodynamic properties and phase equilibria. A literature survey shows a large number of methods for predicting critical properties of different classes of compounds, but no previous study is available to evaluate their suitability for terpenes and terpenoids. In this work, the critical properties of terpenes and terpenoids were first estimated using the group-contribution methods of Joback, Constantinou and Gani, and Wilson and Jasperson. These were then used to calculate densities and vapor pressure through the equations of state Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) and then compared with the experimental values. On other hand, density and vapor pressure experimental data were used to estimate the critical properties directly by the same equations of state (EoSs), allowing a comparison between the two estimation procedures. For this purpose densities for 17 pure terpenes and terpenoids were here measured at atmospheric pressure in the temperature range (278.15 to 368.15) K. Using the first approach, the best combination is the Joback's method with the Peng-Robinson EoS, despite the high relative deviations found for vapor pressure calculations and difficulties to predict density at low temperatures. Following the second approach, the set of critical properties and acentric factors estimated are able to adequately correlate the experimental data. Both equatio ns show a similar capability to correlate the data with SRK EoS presenting a global %ARD of 3.16 and 0.62 for vapor pressure and density, respectively; while the PR EoS presented 3.61 and 0.66, for the same properties, both giving critical properties estimates also closer to those calculated by the Joback method, which is the recommended group-contribution method for this type of compounds.This work was developed in the scope of the projects POCI-01- 0145-FEDER-007679-CICECO-Aveiro Institute of Materials (ref. FCT UID/CTM/50011/2013), POCI-01-0145-FEDER- 006984−Associate Laboratory LSRE-LCM both funded by European Regional Development Fund (ERDF) through COMPETE2020, Programa Operacional Competitividade e Internacionalização (POCI), and by national funds through FCT (Fundação para a Ciência e a Tecnologia). This work is also a result of project “AIProcMat@N2020 (Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020)”, with the reference NORTE-01- 0145-FEDER-000006, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through ERDF. M.A.R.M. acknowledges FCT for her Ph.D. grant (SFRH/BD/87084/ 2012) and COST for the STSM Grant from COST action CM1206. P. J. Carvalho also acknowledges FCT for a contract under the Investigador FCT 2015, Contract No. IF/00758/ 2015. A.M.P. acknowledges Infochem-KBC for his Ph.D. grant. The software Multiflash from Infochem-KBC was applied in some of the calculationsinfo:eu-repo/semantics/publishedVersio

    Solubility of caffeic acid in CO2 + ethanol: experimental and predicted data using Cubic Plus Association Equation of State

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    This work evaluated the solubility of caffeic acid (CA) in mixtures of supercritical carbon dioxide (scCO2) and ethanol at different temperatures (313, 323 and 333 K), pressures (20, 30 and 40 MPa) and concentrations of ethanol (2.2, 5.4 and 10.2 mol%). The Soave-Redlich-Kwong and Cubic Plus Association (CPA) equations of state were used to correlate the binary mixture data and to predict the ternary system data. CA solubility in ethanol is approximately 106 times higher than its solubility in pure scCO2. By using 10.2 mol% ethanol in scCO2, CA solubility increased 30,000 times at 313 K and 20 MPa. Both models provided reasonable descriptions of the experimental data for the binary systems. However, CPA-EoS can better describe the strong interactions between acid molecules and ethanol, and can predict that the addition of small amounts of ethanol to scCO2 provides a large increase in CA solubility.publishe

    Thermodynamic characterization of deep eutectic solvents at high pressures

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    Despite the large spectrum of applications being reported for DESs over the last decade, their thermodynamic characterization is often neglected, hindering a better understanding of their nature, and the development of accurate and robust thermodynamic models to describe them, essential for the conceptual and design stages of new industrial processes. This work aims at decreasing such a gap in literature by reporting new experimental density and viscosity data in wide temperature and pressure ranges for the three archetypal DESs of cholinium chloride, as hydrogen bond acceptor, combined with either ethylene glycol, glycerol, or urea, as hydrogen bond donor. The experimental data measured in this work were then correlated using the Perturbed Chain - Statistical Associating Fluid Theory equation of state coupled with the Free Volume Theory to assess the performance of existing coarse-grained models when applied to the description of DESs. The modelling results obtained highlight the limitation of the existing models, since a correct prediction of DES density could not be achieved, reinforcing the need for viable alternative approaches for the development of coarse-grained models that are appropriate for the thermodynamic modelling of DESs.publishe

    Molecular characterization of Listeria monocytogenes from beef samples and cattle slaughterhouses located in the Federal District, Brazil

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    Este trabalho teve como objetivo realizar a detecção de cepas de Listeria monocytogenes de cortes cárneos bovinos bem como no ambiente de abatedouros frigoríficos localizados no Distrito Federal, promover a sorotipificação pela reação em cadeia da polimerase (PCR), realizar antibiograma e submeter às cepas à eletroforese de campo pulsado (Pulsed-field gel electrophoresis - PFGE). Foram analisados um total de 125 cortes cárneos bovinos, 45 amostras de swabs de carcaças e 43 amostras de swabs em que foram detectados 13 cepas de Listeria monocytogenes, sendo 11 em cortes cárneos bovinos e 2 swabs de ambiente em um abatedouro frigorifico. Não foram isoladas cepas de swabs de carcaça. Dentre as 13 cepas de Listeria monocytogenes foram encontradas seis cepas do sorotipo 4b, cinco do sorotipo 1/2c e duas cepas do sorotipo 1/2a. Dentre as 11 cepas de L. monocytogenes encontradas em cortes cárneos bovino, uma (9,1%) cepa apresentou resistência a eritromicina, outra (9,1%) cepa a gentamicina e outra a ciprofloxacina (9,1%) e todas as cepas (100%) apresentaram resistência ao Ác. Nalidíxico. Das duas (2) cepas oriundas de ralos de abatedouro frigorífico, todas (100%) apresentaram resistência ao Ác. Nalidíxico e a sulfonamidas. A análise por eletroforese de campo pulsante (PFGE) demonstrou 13 diferentes pulsotipos, em que foram agrupados em 3 diferentes grupos clonais, que coincidentemente se correlacionavam com os 3 diferentes sorotipos encontrados sugerindo uma ampla disseminação desses perfis no Distrito Federal.The aim of the study was the analysis of Listeria monocytogenes strains in beef samples as well as slaughterhouse environment, located in the Federal District, promote serotyping by polymerase chain reaction (PCR), perform antibiotic susceptibility and submit the strains to Pulsed-field gel electrophoresis (PFGE). A total of 125 beef samples were analyzed, 45 samples of carcasses swabs and 43 swab samples. It detected 13 strains of Listeria monocytogenes, 11 in beef samples. and 2 in slaughterhouse environment. No carcass swabs strains were isolated. Among the 13 strains of L. monocytogenes six strains of serotype 4b were found, five serotype 1/2c and two strains of serotype 1/2a. Among the 11 strains of L. monocytogenes found in beef, one (9.1%) strain showed resistance to erythromycin, one (9.1%) strain to gentamicin, one to ciprofloxacin (9.1%) and all strains (100%) were resistant to nalidixic acid. The two strains coming from the slaughterhouse drains, all (100%) were resistant to nalidixic acid and Sulfonamides. The analysis by pulsed field gel electrophoresis (PFGE) showed 13 different pulsotypes; they were grouped into three different clonal groups, coincidentally correlated with the three different serotypes found, what suggests a widespread dissemination of these profiles in the Federal District, Brazil

    Unraveling Island Economies through Organic Residue Analysis: The Case of Mocha Island (Southern Chile)

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    Biophysical conditions played a fundamental role in early human colonization of insular territories, particularly in food-producing societies dealing with limited resources and the challenges of maintaining a sustainable carrying capacity. Studies on past human colonization of small oceanic islands thus offer insights into economic plasticity, ecological impacts, and adaptation of early food-producing groups. On the coast of southern Chile, early evidence is dated to 950 cal BP of island colonization by coastal populations with mainland subsistence systems based on the exploitation of marine resources, along with gathering, managing, and cultivating plants and hunting terrestrial animals. Strikingly, the extent to which these mixed economies contributed to insular colonization efforts is largely unknown. Here we used organic residue analysis of ceramic artifacts to shed light on the subsistence of populations on Mocha Island in southern Chile. We extracted and analyzed lipids from 51 pottery sherds associated with the El Vergel cultural complex that flourished in southern Chile between 950 and 400 cal BP. Chemical and stable isotope analysis of the extracts identified a range of food products, including C3 and C4 plants and marine organisms. The results reveal the central role of mixed subsistence systems in fueling the colonization of Mocha Island

    All-sky Search for High-Energy Neutrinos from Gravitational Wave Event GW170104 with the ANTARES Neutrino Telescope

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    Advanced LIGO detected a significant gravitational wave signal (GW170104) originating from the coalescence of two black holes during the second observation run on January 4th^{\textrm{th}}, 2017. An all-sky high-energy neutrino follow-up search has been made using data from the ANTARES neutrino telescope, including both upgoing and downgoing events in two separate analyses. No neutrino candidates were found within ±500\pm500 s around the GW event time nor any time clustering of events over an extended time window of ±3\pm3 months. The non-detection is used to constrain isotropic-equivalent high-energy neutrino emission from GW170104 to less than 4×1054\sim4\times 10^{54} erg for a E2E^{-2} spectrum

    The ANTARES Collaboration: Contributions to ICRC 2017 Part I: Neutrino astronomy (diffuse fluxes and point sources)

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    Papers on neutrino astronomy (diffuse fluxes and point sources, prepared for the 35th International Cosmic Ray Conference (ICRC 2017, Busan, South Korea) by the ANTARES Collaboratio

    The ANTARES Collaboration: Contributions to ICRC 2017 Part II: The multi-messenger program

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    Papers on the ANTARES multi-messenger program, prepared for the 35th International Cosmic Ray Conference (ICRC 2017, Busan, South Korea) by the ANTARES Collaboratio

    The ANTARES Collaboration: Contributions to ICRC 2017 Part III: Searches for dark matter and exotics, neutrino oscillations and detector calibration

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    Papers on the searches for dark matter and exotics, neutrino oscillations and detector calibration, prepared for the 35th International Cosmic Ray Conference (ICRC 2017, Busan, South Korea) by the ANTARES Collaboratio

    A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

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    We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access area to figures, tables at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000
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