Phase equilibria of phenolic compounds in aqueous, organic and supercritical solvents

Phenolic compounds are relevant chemicals in industrial and biological processes. Their production, either by synthesis or extraction from biological media, requires the knowledge of phase equilibrium data that is lacking considerably in the open literature. For this reason, we have been performing at our laboratory a series of experimental measurements of solubility in water (1,2] and organic solvents, focused on two important families of phenolics: hydroxybenzoic and phenylpropenoic acids. The analytical shake flask method was employed for generating the saturated solutions, followed by quantitative analysis by Uv-vis spectrophotometry and/or gravimetry [1,2]. Alternatively, a synthetic method using DSC is being implemented, as this is faster and requires smaller amounts of solid. For a better understanding of the solubilization process, the corresponding melting properties were determined by DSC, with the exception of those phenolics that decompose upon melting, such as Do-coumaric, gallic and caffeic acids. For these, the Marrero and Gani group-contribution procedure [3] was used to generate estimates of the melting properties [1]. Since the studied molecules are organic acids, dissociation constants were also determined by potentiometric titratpon. As these compounds represent a class of associating molecules containing different associating groups such as hydroxyl and carboxyl (in many cases with, multiple substitutions), a new methodology for modeling these multifunctional compounds with the cubic-plus-association (CM) equation of state was developed. In this, the three cubic term parameters (a0, ci and b) are obtained from correlations involving the critical temperature and pressure, and van der Waals volumes, while the association term parameters depend on the nature and positron of each associating group (1,2]. Results showed that this methodology for the pure component parameters can lead to a good description of the aqueous solubility of phenolics using a single, small and temperature independent binary interaction parameter in the physical contribution of CPA. Further results for organic and supercritical solvents using the same methodology will be presented during the meeting

Solubility of phenolic compounds in water, organic and supercritical solvents

Phenolic compounds represent a class of important chemicals with both biological and industrial importance. Their production, either by chemical synthesis or extraction from different biological media requires the adequate knowledge of phase equilibria. Particularly, the solubility in aqueous systems organic and supercritical solvents are fundamental for a better design of separation and purification processes

Measurements and modeling of the solubility of naturally-occurring phenolics

Phenolic compounds are well known for their biological activity and, due to their reactivity, are important starting materials for the synthesis of complex molecules. These compounds can be obtained either by chemical synthesis or by extraction from different biological media. Thus, solubility in aqueous systems, organic and supercritical solvents are fundamental for a better design of reaction, separation and purification processes involving these molecules. For phenolics not many phase equilibria data are available. Usually, when data are reported, only a limited range of thermodynamic conditions is presented, and for many of the more complex phenolics data are extremely scarce or unavailable. In our laboratory we have been implementing a systematic study on the solubility of different hydroxybenzoic, phenylpropenoic and more complex phenolics in water and several organic solvents. Solubilities were determined using the analytical shake-flask method for generating the saturated solutions, followed by compositional analysis by Uv-vis spectrophotometry, HPLC and/or gravimetry [1,2]. A synthetic method based on the use of differential scanning calorimetry (DSC) for determining solubilities has also been investigated. For better understanding the solubilization process, melting properties (Tfus and DfusH) were determined by DSC and aqueous acid dissociation constants by potentiometric titration [1, 2]. Modeling was performed with the Cubic-plus-Association (CPA) equation of state, where a predictive methodology for obtaining the pure component parameters solely from the chemical structure is proposed. In this, the cubic parameters are obtained from correlations involving Tc, Pc and the van der Waals volume, while the association term parameters depend on the nature and position of each associating group [1,2]. Results showed that a good description of the solubility of phenolics using a single, small and temperature independent binary interaction parameter can be obtained in different solvents

Automatic generation of test cases from requirements

Dissertação de mestrado integrado em Engenharia e Gestão de Sistemas de InformaçãoO facto de vivermos num mundo cada vez mais informatizado e em que os sistemas informáticos já fazem parte do quotidiano das pessoas e das organizações levou a que os sistemas informáticos se tornassem cada vez maiores e mais complexos. Para se construir um sistema que dê resposta ao pretendido e que tenha qualidade, existe um processo de desenvolvimento que deve ser seguido. Durante o processo de desenvolvimento de software existem várias etapas pelas quais se tem de passar, uma dessas etapas é a de testes. Sendo a etapa de testes uma das mais “caras” em termos de recursos e tempo no processo de desenvolvimento de software, a automatização de processos que compõem esta área tornou-se um dos principais desafios e interesses para as organizações. Assim, nasceu a necessidade de se construir uma ferramenta que a partir dos requisitos especificados para um projeto de software conseguir-se identificar quais os casos de teste de uma forma automática, garantindo, não só, uma maior rapidez mas também uma maior qualidade no processo de identificação de casos de teste. O que consequentemente faz com que seja desenvolvido um produto de melhor qualidade. Deste modo, o tema abordado neste documento baseia-se no desenvolvimento de uma solução para um problema numa organização real. O facto da solução abordada neste documento ser realizada para uma organização real, faz com que existam processos e abordagens utilizadas na organização com as quais se tem de trabalhar. Uma das abordagens utilizadas na organização e consequentemente utilizadas para a criação da solução descrita neste documento é o conceito de DSL (Domain-Specific Languages), que são linguagens criadas para um domínio especifico e as quais são utilizadas nesta solução para a especificação dos casos de teste. Este trabalho apresenta uma contribuição para a área de testes de software, com a aplicação de uma solução que permita a identificação de casos de teste de uma forma automática a partir de requisitos especificados para um determinado projeto.The fact that we live in a world increasingly computerized and the computer systems that are already part of everyday life of people and organizations that led to the computer systems become increasingly larger and more complex. To build a system that is responsive and has the desired quality, there is a developmental process that must be followed. During the process of software development there are various stages through which it must pass one of these steps is to test. As the stage of testing one of the most "expensive" in terms of resources and time in the software development process, the automation of processes that make up this area has become a major challenge for organizations and interests. So, the need to build a tool that was born from the specified requirements for a software project get to identify which test cases in an automated manner, ensuring not only greater speed but also a higher quality process identification of test cases. What therefore causes a better quality product is developed. This way, the issue addressed in this document is based on developing a solution to a problem in a real organization. The fact that the solution discussed in this document be performed to a real organization, means that there are processes and approaches used in the organization with whom they must work. One of the approaches used in the organization and consequently used to create the solution described in this paper is the concept of DSL (Domain-Specific Languages) are languages created for a specific domain and which are used in this solution for the specification of cases test. This work presents a contribution to the field of software testing, with the application of a solution that enables the identification of cases in an automatic way from test requirements specified for a particular project

Towards Personalized Neural Networks for Epileptic Seizure Prediction

Seizure prediction for untreatable epileptic patients, one of the major challenges of present neuroinformatics researchers, will allow a substantial improvement in their safety and quality of life. Neural networks, because of their plasticity and degrees of freedom, seem to be a good approach to consider the enormous variability of physiological systems. Several architectures and training algorithms are comparatively proposed in this work showing that it is possible to find an adequate network for one patient, but care must be taken to generalize to other patients. It is claimed that each patient will have his (her) own seizure prediction algorithms

Mesenchymal stem cell secretome improves tendon cell viability in vitro and tendon-bone healing in vivo when a tissue engineering strategy is used in a rat model of chronic massive rotator cuff tear

BACKGROUND: Massive rotator cuff tears (MRCTs) represent a major clinical concern, especially when degeneration and chronicity are involved, which highly compromise healing capacity. PURPOSE: To study the effect of the secretome of mesenchymal stem cells (MSCs) on tendon cells (TCs) followed by the combination of these activated TCs with an electrospun keratin-based scaffold to develop a tissue engineering strategy to improve tendon-bone interface (TBi) healing in a chronic MRCT rat model. STUDY DESIGN: Controlled laboratory study. METHODS: Human TCs (hTCs) cultured with the human MSCs (hMSCs) secretome (as conditioned media [CM]) were combined with keratin electrospun scaffolds and further implanted in a chronic MRCT rat model. Wistar-Han rats (N = 15) were randomly assigned to 1 of 3 groups: untreated lesion (MRCT group, n = 5), lesion treated with a scaffold only (scaffold-only group, n = 5), and lesion treated with a scaffold seeded with hTCs preconditioned with hMSCs-CM (STC_hMSC_CM group, n = 5). After sacrifice, 16 weeks after surgery, the rotator cuff TBi was harvested for histological analysis and biomechanical testing. RESULTS: The hMSCs secretome increased hTCs viability and density in vitro. In vivo, a significant improvement of the tendon maturing score was observed in the STC_hMSC_CM group (mean ± standard error of the mean, 15.6 ± 1.08) compared with the MRCT group (11.0 ± 1.38; P < .05). Biomechanical tests revealed a significant increase in the total elongation to rupture (STC_hMSC_CM, 11.99 ± 3.30 mm; scaffold-only, 9.89 ± 3.47 mm; MRCT, 5.86 ± 3.16 mm; P < .05) as well as a lower stiffness (STC_hMSC_CM, 6.25 ± 1.74 N/mm; scaffold-only, 6.72 ± 1.28 N/mm; MRCT, 11.54 ± 2.99 N/mm; P < .01). CONCLUSION: The results demonstrated that hMSCs-CM increased hTCs viability and density in vitro. Clear benefits also were observed when these primed cells were integrated into a tissue engineering strategy with an electrospun keratin scaffold, as evidenced by improved histological and biomechanical properties for the STC_hMSC_CM group compared with the MRCT group. CLINICAL RELEVANCE: This work supports further investigation into the use of MSC secretome for priming TCs toward a more differentiated phenotype, and it promotes the tissue engineering strategy as a promising modality to help improve treatment outcomes for chronic MRCTs.info:eu-repo/semantics/publishedVersio