Universidade Federal de Santa Catarina

About: Universidade Federal de Santa Catarina is a education organization based out in Florianópolis, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 28408 authors who have published 55433 publications receiving 714461 citations.

Arenediazonium Salts: New Probes of the Interfacial Compositions of Association Colloids. 6. Relationships between Interfacial Counterion and Water Concentrations and Surfactant Headgroup Size, Sphere-to-Rod Transitions, and Chemical Reactivity in Cationic Micelles†

Abstract: Product yields measured by high-performance liquid chromatography from chemical trapping of Cl-, Br-, and H2O by an aggregate-bound arenediazonium ion in cetyltrialkylammonium halide {(CTRA)X, R = Me, Et, n-Pr, and n-Bu; X = Cl, Br}, micelles are used to estimate, simultaneously, interfacial counterion, Xm, and water, H2Om, concentrations as a function of [(CTRA)X] and tetramethylammonium halide concentrations, [(TMA)X]. The results are interpreted by using a two-site pseudophase model. Values of Xm and H2Om are estimated by assuming that when the product yields from reaction of a long-tail aggregate-bound arenediazonium ion in micelles are the same as the product yields from reaction of its short chain analogue in an aqueous quaternary ammonium ion salt solution, then Xm = [Xw] and H2Om = [H2Ow] in those solutions. The results show that Xm and H2Om are functions of headgroup size, surfactant concentration, and aqueous counterion concentration and type. Plots of Xm against [(CTRA)X] at a series of salt co...

Aplicações sintéticas de lipases imobilizadas em polímeros

Abstract: The application of biocatalysis is a promising field related to new technologies for organic synthesis. The development of immobilization techniques is very important due to the multiple or repetitive use of a single batch of enzymes and the ability to stop the reaction rapidly, at any stage, by removing the enzymes. In most cases, after immobilization, enzymes and microorganisms maintain or even increase their activity and stability. This work presents an overview of the common methods for lipase immobilization in polymers and applications of these systems to obtain compounds of synthetic interest.

Caffeine improves spatial learning deficits in an animal model of attention deficit hyperactivity disorder (ADHD) – the spontaneously hypertensive rat (SHR)

Abstract: The spontaneously hypertensive rat (SHR) is generally considered to be a suitable genetic model for the study of attention deficit hyperactivity disorder (ADHD), since it displays hyperactivity, impulsivity, poorly sustained attention, and deficits in learning and memory processes. Converging evidence suggests a primary role of disturbance in the dopaminergic neurotransmission in ADHD patients and in SHR, and in addition, some studies have also demonstrated alterations in adenosinergic neurotransmission in SHR. In the present study, adult female Wistar (WIS) and SHR rats received caffeine (1-10 mg/kg i.p.) 30 min before training, immediately after training, or 30 min before a test session in the spatial version of the Morris water maze. The effect of caffeine administration on WIS and SHR blood pressure was also measured. SHR needed significantly more trials in the training session to acquire the spatial information, but they displayed a similar profile to that of WIS rats in the test session (48 h later), demonstrating a selective deficit in spatial learning. Pre-training administration of caffeine (1-10 mg/kg i.p.) improved this spatial learning deficit in SHR, but did not alter the WIS performance. In contrast, post-training administration of caffeine (3 mg/kg i.p.) did not alter the SHR test performance, but increased memory retention in WIS rats. No dose of caffeine tested altered the mean blood pressure of WIS or SHR. These results demonstrate a selective spatial learning deficit in SHR which can be attenuated by pre-training administration of caffeine. In addition, the present findings indicate that the spatial learning deficit in SHR is not directly related to hypertension.

Food processing for the improvement of plant proteins digestibility.

Abstract: Proteins are essential macronutrients for the human diet. They are the primary source of nitrogen and are fundamental for body structure and functions. The plant protein quality (PPQ) refers to the bioavailability, digestibility, and amino acid composition. The digestibility specifies the protein quantity absorbed by an organism relative to the consumed amount and depends on the protein structure, previous processing, and the presence of compounds limiting the digestion. The latter are so-called antinutritional factors (ANF), exemplified by phytates, tannins, trypsin inhibitors, and lectins. Animal proteins are known to have better digestibility than plant proteins due to the presence of ANF in plants. Thus, the inactivation of ANF throughout food processing may increase the PPQ. New food processing, aiming to increase the digestibility of plant proteins, and new sources of proteins are being studied for the animal protein substitution. Here, it is presented the impact of processing on the protein digestibility and reduction of ANF. Several techniques, such as cooking, autoclaving, germination, microwave, irradiation, spray- and freeze-drying, fermentation, and extrusion enhanced the PPQ. The emerging non-thermal technologies impact on protein functionalities but require studies on the protein digestibility. How to accurately determine and how to improve the protein digestibility of a plant source remains a scientific and technological challenge that may be addressed by novel or combining existing processing techniques, as well as by exploring protein-enriched by-products of the food industry.

Effect of the Ca/Si Molar Ratio on the Micro/nanomechanical Properties of Synthetic C-S-H Measured by Nanoindentation

Abstract: Calcium silicate hydrate (C-S-H), the main product in Portland cement hydration, influences the physical and mechanical properties of most cementitious materials. However, there are no structural models that currently relate chemical composition, nanostructure, and microstructure with the physicochemical and mechanical properties. In this work, the indentation technique was used to evaluate the micro/nanomechanical properties of synthetic C-S-H with different Ca/Si (CaO/SiO2) molar ratios. C-S-H was also characterized by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray fluorescence (XRF). Analysis of the results verified that the elastic modulus and hardness increased when the Ca/Si molar ratio of C-S-H decreased, achieving elastic modulus values of 27 and 20 GPa for Ca/Si ratios of 0.7 and 2.1, respectively, corroborating calculations based on the force field method of Manzano et al.(1) Our results also determined that micro- and nanoporosity significantly influence ...