Um sistema simples para preparação de microesferas de quitosana

This article describes the construction and optimization of an inexpensive apparatus for the production of uniform and porous chitosan microspheres. It also describes the control of the main operational parameters and strategies for the production of uniform chitosan microspheres

Adsorption of BTX (benzene, toluene, o-xylene, and p-xylene) from aqueous solutions by modified periodic mesoporous organosilica

AbstractThe capacity of a periodic mesoporous organosilica (PMO) to adsorb the aromatic compounds benzene, toluene, o-, and p-xylenes (BTX), which are usually present in produced waters, was investigated under both column and batch processes. The PMO was synthesized by condensation of 1,4 bis(triethoxisilyl)benzene (BTEB) under acidic conditions by using structure-directing agent (SDA) Pluronic P123 in the presence of KCl. Thermogravimetric analysis showed that the presence of the surfactant decreases the thermal stability of the PMO. The small-angle X-ray diffraction pattern, as well as the nitrogen adsorption/desorption isotherm measurements, revealed that the synthesized material has a crystalline structure, with hexagonally-ordered cylindrical mesopores. The adsorption kinetics study indicated an adsorption equilibrium time of 50min and also showed that the data best fitted the pseudo-first order kinetic model. The intraparticle diffusion model was also tested and pointed to the occurrence of such process in all cases. Both Langmuir and Temkin models best represented the adsorption isotherms of toluene; Langmuir and Redlich–Peterson models best represented the data obtained for the other compounds. Adsorption capacity decreases in the order benzene>o-xylene>p-xylene>toluene. Satisfactory results were observed in the application of the synthesized PMO for the removal of BTX from aqueous solution

Extraction techniques and clean-up procedures for the determination of pahs in sediments of the Ceará coast

Extraction and clean-up are essential points in polycyclic aromatic hydrocarbon (PAHs) analysis in a solid matrix. This work compares extraction techniques and clean-up procedures for PAH analysis. PAH levels, their toxicological significance and source were also evaluated in the waters of the Cocó and Ceará rivers. The efficiency of PAH recovery was higher for the soxhlet and ultrasonic techniques. PAH recovery varied from 69.3 to 99.3%. Total PAH concentration (ΣHPA) varied from 720.73 to 2234.76 µg kg-1 (Cocó river) and 96.4 to 1859.21 µg kg-1 (Ceará river). The main PAH sources are pyrolytic processes and the levels were classified as medium so that adverse effects are possible

Removal of phenol and conventional pollutants from aqueous effluent by chitosan and chitin

The present study deals with phenol adsorption on chitin and chitosan and removal of contaminants from wastewater of a petroleum refinery. The adsorption kinetic data were best fitted to first- and second-order models for chitosan and chitin, respectively. The results of adsorption isotherms showed Langmuir model more appropriately described than a Freundlich model for both adsorbents. The adsorption capacity was 1.96 and 1.26 mg/g for chitin and chitosan, respectively. Maximum removal of phenol was about 70-80% (flow rate: 1.5 mL/min, bed height: 18.5 cm, and 30 mg/L of phenol. Wastewater treatment with chitin in a fixed-bed system showed reductions of about 52 and 92% for COD and oil and greases, and for chitosan 65 and 67%, respectively. The results show improvement of the effluent quality after treatment with chitin and chitosan

Apolipoprotein E polymorphism influences orthotopic liver transplantation outcomes in patients with hepatitis C virus-induced liver cirrhosis

BACKGROUND: Hepatitis C virus (HCV) infection is responsible for a chronic liver inflammation, which may cause end-stage liver disease and hepatocellular carcinoma. Apolipoprotein E (protein: ApoE, gene: APOE), a key player in cholesterol metabolism, is mainly synthesized in the liver and APOE polymorphisms may influence HCV-induced liver damage. AIM: To determine whether APOE alleles affect outcomes in HCV-infected patients with liver cirrhosis following orthotopic liver transplantation (OLT). METHODS: This was a cohort study in which 179 patients, both genders and aged 34-70 years, were included before or after (up to 10 years follow-up) OLT. Liver injury severity was assessed using different criteria, including METAVIR and models for end-stage liver disease. APOE polymorphisms were analyzed by quantitative real-time polymerase chain reaction. RESULTS: The APOE3 allele was the most common (67.3%). In inflammation severity of biopsies from 89 OLT explants and 2 patients in pre-transplant, the degree of severe inflammation (A3F4, 0.0%) was significantly less frequent than in patients with minimal and moderate degree of inflammation (≤ A2F4, 16.2%) P = 0.048, in patients carrying the APOE4 allele when compared to non-APOE4. In addition, a significant difference was also found (≤ A2F4, 64.4% vs A3F4, 0.0%; P = 0.043) and (A1F4, 57.4% vs A3F4, 0.0%; P = 0.024) in APOE4 patients when compared to APOE3 carriers. The fibrosis degree of the liver graft in 8 of 91 patients and the lack of the E4 allele was associated with more moderate fibrosis (F2) (P = 0.006). CONCLUSION: Our results suggest that the E4 allele protects against progression of liver fibrosis and degree of inflammation in HCV-infected patients

USE OF COCONUT BAGASSE AS ALTERNATIVE ADSORBENT FOR SEPARATION OF COPPER (II) IONS FROM AQUEOUS SOLUTIONS: ISOTHERMS, KINETICS, AND THERMODYNAMIC STUDIES

The use of coconut bagasse as an adsorbent for the treatment of Cu(II) ions from aqueous solutions has been investigated. The adsorbent was characterized by infrared spectroscopy, including zeta potential and pH effects. To assess the possibility of removing Cu(II) from aqueous solutions by this sorbent the effects of contact time, initial metal ion concentration, and temperature were studied at pH 5.5. Kinetic studies showed that the amount adsorbed increased with initial Cu(II) concentration, and the equilibrium was established in 120 min. The kinetic data were analyzed using a pseudo second-order equation. Adsorption equilibrium data were investigated using the Langmiur, Freundlich, D–R, Temkin and Halsey isotherm models. The adsorption of Cu(II) on the coconut bagasse was endothermic (H◦ 86.2 kJ/mol), resulting in an increase in entropy (S◦ 339 J/mol/K) and a decrease in Gibbs free energy (G -16.34 to -22.44 kJ/mol) in the temperature range of 301-313 K. A reduction in adsorption capacity with an increase in heat of adsorption revealed an ion exchange mechanism for Cu(II) adsorption

Constituintes químicos de Capraria biflora (Scrophulariaceae) e atividade larvicida de seu óleo essencial

Analysis of essential oil from fresh leaves of Capraria biflora allowed identification of fourteen essential oil constituents among which thirteen are sesquiterpene compounds, and α-humulene (43.0%) the major constituent. The essential oil was tested for larvicidal activity against Aedes aegypti showing good activity, with LC50 73.39 µg/mL (2.27 g/mL). Chromatographic studies of extracts from roots and stems allowed the isolation of five compounds: naphthoquinone biflorin, sesquiterpene caprariolide B, the steroid β-sitosterol, the carbohydrate D-mannitol and iridoid myopochlorin first reported in the species C. biflora. The structures of compounds were characterized by spectroscopic data, IR, MS, NMR13C, NMR¹H, NOE, HSQC and HMBC

Estudos Artísticos

O número 18 da revista Gama apresenta 16 artigos respondendo ao desafio a editorial lançado por esta revista. Trata-se de apresentar a obra de artistas contemporâneos ou mais antigos numa perspetiva de um resgate patrimonial, uma revisitação valorizadora do seu testemunho artístico.info:eu-repo/semantics/publishedVersio