81 research outputs found
Solubilities of Amino Acids in the Presence of Chaotropic Anions
This work addresses the effect of chaotropic anions (thiocyanate and tosylate) on the solubility of glycine, L-leucine, L-phenylalanine, and L-aspartic acid in aqueous solutions at 298.2 K. The salts used were NaSCN, KSCN, NH4SCN, and NaC7H7SO3 (sodium tosylate), with salt concentrations ranging from 0 to 2 molal. The pH of the saturated solutions was registered, and solid-phase studies were also performed. All the thiocyanate salts and sodium tosylate induced a salting-in effect, except in the systems composed of glycine in aqueous sodium tosylate solutions at 0.5 and 1 molal. For L-leucine, L-phenylalanine, and L-aspartic acid the salting effect of anions followed the order tosylate− > SCN− > NO3- > Cl−, in good agreement with the behavior predicted by the Hofmeister series. Differently, the relative solubility of glycine in aqueous nitrate solutions was higher than in those containing thiocyanate, followed by the chloride and, closing the rank, the solutions containing the tosylate anion, suggesting that the solubility change in this case is achieved by a different mechanism.This work was developed within the scope of the project CIMO-Mountain Research
Center, UIDB/00690/2020 and LA/P/0007/2020 and CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 and LA/P/0006/2020, financed by national funds through the Portuguese Foundation
for Science and Technology (FCT)/MCTES. Mehriban Aliyeva thanks FCT and European Social Fund
(ESF) for her Ph.D. grant (SFRH/BD/139355/2018).info:eu-repo/semantics/publishedVersio
Solvent and temperature effects on the solubility of syringic, vanillic or veratric acids: Experimental, modeling and solid phase studies
The solubility of syringic acid, vanillic acid and veratric acid was measured in pure water and eleven organic solvents
(methanol, ethanol, 1-propanol, 2-propanol, 2-butanone, ethyl acetate, acetonitrile, dimethylformamide,
1,2-propanediol, 1,3-propanediol and 1,3-butanediol), at 298.2 K and 313.2 K. Besides the solubility data, the
melting temperatures and enthalpies of the solutes were determined by differential scanning calorimetry,
while powder and single X-ray diffractionwere used to resolve the solute solid structure, before and after the solubility
studies.
Formodeling purposes, theNRTL-SACmodel, also combinedwith the Reference Solvent Approach (RSA), and the
Abraham solvation model were applied to describe the solid-liquid equilibria of the binary systems. A set of solvents
was used to estimate the model parameters and afterwards, solubility predictions were carried out for binary
systems not included in the correlation step. Better results were obtained using the Abraham solvation
model with average relative deviations (ARD) of 15% for the correlation set and 26% for the predictions, which
are more satisfactory than the results found with the NRTL-SAC model (33% for the correlation and 59% for the
predictions) or the NRTL-SAC model combined with RSA (30% for the correlation and 59% for the predictions).We acknowledge the support of the 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
the European Regional Development Fund (ERDF); Associate Laboratory
LSRE-LCM - UID/EQU/50020/2019 - funded by national funds through
FCT/MCTES (PIDDAC); UID/CTM/50011/2019 (CICECO), financed by national
funds through the FCT/MCTES; and project AllNat - POCI-01-
0145-FEDER-030463 (PTDC/EQU-EPQ/30463/2017), financed by FEDER funds through COMPETE and Portugal2020 and national funds through
FCT - Fundação para a Ciência e a Tecnologia.
The authors also thank FCT for financial support to S. M. Vilas-Boas
grant (SFRH/BD/138149/2018) and V. Vieira grant (SFRH/BD/108487/
2015).info:eu-repo/semantics/publishedVersio
Solid-liquid phase equilibrium of trans-cinnamic acid, p-coumaric acid and ferulic acid in water and organic solvents: Experimental and modelling studies
The solubility of the trans isomers of cinnamic acid, p-coumaric acid and ferulic acid was measured in water and seven organic solvents (methanol, ethanol, 1-propanol, 2-propanol, 2-butanone, ethyl acetate and acetonitrile), at 298.2 K and 313.2 K, using the analytical shake-flask technique. The melting temperatures and enthalpies of the solutes were studied by differential scanning calorimetry, while solute solid structures were identified by powder and single X-ray diffraction. The NRTL-SAC model was applied to calculate the solubility of trans-cinnamic acid and trans-ferulic acid in pure solvents. For trans-p-coumaric acid, the NRTL-SAC was combined with the Reference Solvent Approach, as the solute melting properties could not be determined. The global average relative deviations (ARD) were 32% and 41%, in the correlation and prediction stages, respectively. The Abraham solvation model was also applied. The global ARD were 20% for correlation and 29% for predictions, which can be considered very satisfactory results for these semi-predictive models.This work was developed within the scope of the project
CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/
50011/2020, and CIMO-Mountain Research Center, UIDB/00690/
2020, both financed by national funds through the Portuguese
Foundation for Science and Technology/MCTES. We also acknowledge
the support of the projects “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 the European Regional Development Fund
(ERDF); and project AllNat - POCI-01-0145-FEDER-030463, funded
by the European Regional Development Fund (ERDF) through the
Competitiveness and Internationalization Operational Program
(COMPETE2020-POCI) and national funding from the Foundation
for Science and Technology (FCT, Portugal). S. M. Vilas-Boas thanks
the financial support provided by FCT PhD grant (SFRH/BD/138149/
2018).info:eu-repo/semantics/publishedVersio
Electrolyte effects on the Amino acid solubility in water: solubilities of Glycine, l-Leucine, l-Phenylalanine, and l-Aspartic acid in salt solutions of (Na+, K+, NH4+)/(Cl–, NO3–)
The solubilities of glycine, L-leucine, L-phenylalanine, and L-aspartic acid in aqueous solutions of the salts
composed by combining Na+, K+, and NH4 + cations and Cl− and NO3 − anions were measured up to 2.0 salt molality at 298.2 K by the analytical gravimetric method. Using these data along with a review of literature information, encompassing all amino acids for which solubility is available in the studied aqueous electrolyte solutions, allowed us to interpret the effect of the functional groups of amino acids on their solubility. The four amino acids studied here showed higher solubility in aqueous solutions of salts with the nitrate anion. Except for L-aspartic acid with a polar side chain, amino acids with apolar side chains presented the highest salting-in effect in aqueous salt solutions with NH4 +. The cations Na+ and K+
did not seem to establish relevant interactions with the amino acids and had little impact on their aqueous solubility.This work was developed within the scope of the project
CIMO-Mountain Research Center, UIDB/00690/2020 and
CICECO-Aveiro Institute of Materials, UIDB/50011/2020
and UIDP/50011/2020, financed by national funds through
the Portuguese Foundation for Science and Technology
(FCT)/MCTES. Mehriban Aliyeva thanks FCT and European
Social Fund (ESF) for her Ph.D. grant (SFRH/BD/139355/2018).info:eu-repo/semantics/publishedVersio
The brain decade in debate: II. Panic or anxiety? From animal models to a neurobiological basis
This article is a transcription of an electronic symposium sponsored by the Brazilian Society of Neuroscience and Behavior (SBNeC). Invited researchers from the European Union, North America and Brazil discussed two issues on anxiety, namely whether panic is a very intense anxiety or something else, and what aspects of clinical anxiety are reproduced by animal models. Concerning the first issue, most participants agreed that generalized anxiety and panic disorder are different on the basis of clinical manifestations, drug response and animal models. Also, underlying brain structures, neurotransmitter modulation and hormonal changes seem to involve important differences. It is also common knowledge that existing animal models generate different types of fear/anxiety. A challenge for future research is to establish a good correlation between animal models and nosological classification.Universidade Federal do Paraná Departamento de Farmacologia Laboratório de Fisiologia e Farmacologia do Sistema Nervoso CentralUniversity of Hawaii Department of NeurobiologyUniversity of Hawaii Department of PsychologyUniversidade de São Paulo Faculdade de Filosofia Ciências e Letras de Ribeirão Preto Departamento de PsicobiologiaUniversidade de São Paulo Faculdade de Medicina de Ribeirão Preto Departamento de FisiologiaUniversidade de São Paulo Faculdade de Medicina de Ribeirão Preto Departamento de NeuropsiquiatriaUniversidade Federal de Santa Catarina Departamento de FarmacologiaCentral Nervous System Research Department Sanofi SynthelaboAston University Institute of Pharmaceutical SciencesHoffmann-La Roche Ltd.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de PsicologiaUniversity of Leeds Department of Psychology Ethopharmacology LaboratoryUniversidade Federal do Espírito Santo Centro de Biomedicina Departamento de Ciências FisiológicasUNIFESP, EPM, Depto. de PsicologiaSciEL
Análise de desempenho de medidas estruturais e não estruturais de controle de inundações em uma bacia urbana
Short, medium or long-term hormonal treatments for induction of synchronized estrus and ovulation in Saanen goats during the nonbreeding season
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