Preparation and characterization of polysulfone-polyurethane membranes for recovery of simulated wastewater from industrial textile processes.

Techniques using membranes for the treatment of wastewaters usually promote higher quality of treated water when compared to other processes. Among them, pervaporation has advantages in terms of selectivity in addition to low working pressure, which can prevent clogging problems. Polysulfone and polyurethane have complementary characteristics and are interesting in the context of membranes for industrial applications. In this sense, the aim of this work was to prepare and characterize polysulfone/polyurethane-based membranes and tested them with a simulated wastewater containing the reactive black dye and sodium chloride by pervaporation. In their manufacture, thermal treatment (at 60°C) and photo-radiation treatment (using ultraviolet light) were also applied. The characterizations were performed using different analytical tools. In general, it was possible to verify that all membranes have a dense layer. The thermal analysis allowed to define that the indicated working temperature is below 50°C. With respect to the simulated wastewater treatment, all membranes reached 100% selectivity. Concerning the saline solution, the mean selectivity was around 98.5%. Moreover, the permeate flow values were within the range presented by commercial membranes ranging from 1.6 to 2.4 kg m-2 h-1. Although for the photoirradiated membranes the photo-graft reaction has occurred, among all membranes, the blend without any treatment stood out from the others, presenting the highest permeate flow of the simulated wastewater. Finally, the results reveal that these membranes are capable of recovering wastewater from textile processes, in addition to having the potential to remove salts from water through the pervaporation process.Highlights Polysulfone/polyurethane-based membranes were not yet evaluated for wastewater recovery.Modifications in the membrane characteristics promoted variations in the permeate flow.Changes in physical-chemical properties of membrane as a result of a photoinitiation reaction.Removal efficiency achieved was 100% for reactive black dye and 98.5% for sodium chloride.A new way of performing pervaporation on the recovery of aqueous solutions.

On the phonon dissipation contribution to nanoscale friction by direct contact.

The friction phenomenon is a ubiquitous manifestation of nature. Models considering phononic, electronic, magnetic, and electrostatic interactions are invoked to explain the fundamental forces involved in the friction phenomenon. In order to establish the incidence of the phonon prompting at the nanoscale friction by direct contact, we study a diamond spherical dome sliding on carbon thin films containing different amount of deuterium and hydrogen. The friction coefficient decreases by substituting hydrogen by deuterium atoms. This result is consistent with an energy dissipation vibration local mechanism from a disordered distribution of bond terminators.

Preparação e caracterização inicial de complexo de inclusão entre nitrofurazona e 2-hidroxipropil-Beta-ciclodextrina / Preparation and initial characterization of inclusion complex between nitrofurazone and 2-hydroxypropyl-Beta-cyclodextrin

Nitrofurazona(NF), 5-nitro-2-furaldeído semicarbazona, é um antibiótico de amplo espectro, que apresenta diversos efeitos tóxicos e baixa solubilidade aquosa. A complexação da NF com ciclodextrinas é de grande interesse para o desenvolvimento de uma formulação para este antibiótico que seja mais segura e eficiente. Neste trabalho foi realizada a preparação e caracterização inicial do complexo de inclusão entre NF e hidroxipropil-Beta-ciclodextrina (HP-Beta-CD) através de experimentos para determinação da cinética de complexação, medidas de fotoestabilidade, medidas de constante de afinidade fármaco: ciclodextrina, ensaios de liberação in vitro, estequiometria de formação do complexo e morfologia do complexo por microscopia eletrônica de varredura. Os ensaios de cinética de complexação mostram que para o complexo atingir o equilíbrio são necessárias 17,3h. As isotermas de solubilidade determinadas para a NF em função da temperatura mostraram perfis do tipo A e B indicando que a temperatura é um fator importante na complexação da NF com ciclodextrina. Os experimentos de fotoestabilidade indicam que a inserção da molécula de NF na cavidade interna da ciclodextrina protege o fármaco da fotodecomposição. A cinética de liberação mostra que o perfil de liberação do fármaco é modificado pela presença da ciclodextrina no meio. A estequiometria de complexação entre NF e HP-Beta-CD determinada foi de 1:1 NF:HP-Beta-CD. Os resultados demicroscopia eletrônica de varredura indicam alterações na estrutura cristalina da NF em presença deciclodextrina. Este estudo está baseado na caracterização físico-química da complexação entre NF e HP-Beta-CD podendo ser uma nova potencial opção para utilização terapêutica do NF.

Nitrofurazone (NF), 5-nitro-2-furaldehyde semicarbazone, a broad-spectrum antibiotic, has reported toxic effects and low solubility in water. It would be of great interest to form inclusion complexes between NF and a cyclodextrin, to develop more effective and safer antibiotic formulations. This paper focuses on the preparation of inclusion complexes of NF with 2- hydroxypropyl- -cyclodextrin (HP- -CD) and their initial characterization by evaluating rates of complex formation, photostability, solubility isotherms, release rate profiles, stoichiometry of the complexes and their morphology, as revealed by scanning electron microscopy. The kinetic tests of complex formation revealed that 17,3 h is enough for stabilization of the NFcyclodextrin complex. The solubility isotherm studies showed that the isotherm changes from type A to type B, as a function of temperature. The photostability experiments showed that the insertion of the NF in the HP- -CD cavity protects the drug from photodecomposition. The release kinetic tests showed that the profile of NF release from the complex is altered by the presence of HP- -CD in the medium. A Job's plot indicated that the stoichiometry of the complex was 1:1 NF:HP- -CD. The scanning electron micrographs showed changes in the crystal structure of NF in the complex. This study focused on the physicochemical properties of drug-delivery formulations that could potentially be developed into a novel type of therapy with NF.

In vitro evaluation of quinidine sensitivity in Brazilian Plasmodium falciparum isolates: comparative analysis to quinine and chloroquine.

Falciparum malaria represents a serious and an increasing world public health problem due to the acquired parasite's resistance to the most available drugs. In some endemic areas, quinidine, a diastereoisomer of the antimalarial quinine, has been employed for replacing the latter. In order to evaluate the use of quinidine as an alternative to the increasing loss of quinine effectiveness in Brazilian P. falciparum strains, as has been observed in the Amazon area, we have assayed quinidine, quinine and chloroquine. The in vitro microtechnique was employed. All isolates showed to be highly resistant to chloroquine. Resistance to quinine was not noted although high MIC (minimal inhibitory concentration) values have been observed. These data corroborate the decreasing sensitivity to quinine in strains from Brazil. Quinidine showed IC50 from 0.053 to 4.577 micromol/L of blood while IC50 from 0.053 to 8.132 micromol/L of blood was estimated for quinine. Moreover, clearance of the parasitemia was observed in concentrations lower than that used for quinidine in antiarrhythmic therapy, confirming our previous data. The results were similar to African isolate.

Second intention healing after Mohs micrographic surgery.

BACKGROUND: Although second intention healing has been used for many years in Mohs micrographic surgery, it has lost popularity. This is due to the long process and functional alteration of important anatomical units if certain wound healing factors are not carefully taken into consideration. OBJECTIVE: To review indications, contraindications, complications, advantages, disadvantages, as well as basic concepts of the wound healing process, wound care and antibiotic prophylaxis in the management of open wounds after Mohs surgery. METHODS: A short but comprehensive review of studies published in the literature dealing with second intention healing as a reconstruction alternative option in certain situations. CONCLUSIONS: Second intention healing is a simple and cost-effective method for reconstruction after Mohs micrographic surgery in well-defined cases. It allows adequate tumoral control with good to excellent functional and cosmetic results.

In vitro evaluation of erythromycin in chloroquine resistant brazilian P. falciparum freshly isolates: modulating effect and antimalarial activity evidence.

Erythromycin, a reversal agent in multidrug-resistant cancer, was assayed in chloroquine resistance modulation. The in vitro microtechnique for drug susceptibility was employed using two freshly isolates of Plasmodium falciparum from North of Brazil. The antimalarial effect of the drug was confirmed, with an IC50 estimates near the usual antimicrobial therapy concentration, and a significant statistical modulating action was observed for one isolate.

Antimalarial effect in vitro and lack of modulating effect of desipramine and imipramine.

Based on previous studies in vitro of the modulating effect of desipramine on chloroquine-resistance of Plasmodium falciparum, the effect of desipramine and imipramine on freshly isolated resistant Brazilian strains of the parasite was investigated. Both drugs in therapeutic doses showed an unexpected antimalarial effect in vitro in duplicate tests (IC50 = 44.26 and 46.53 micrograms/L for desipramine, and 83.93 and 41.26 micrograms/L for imipramine), but no reversal of resistance when added to cultures together with chloroquine.