Effect of carboxylic acids as compatibilizer agent on mechanical properties of thermoplastic starch and polypropylene blends.

In this work, polypropylene/thermoplastic starch (PP/TPS) blends were prepared as an alternative material to use in disposable packaging, reducing the negative polymeric environmental impact. Unfortunately, this material displays morphological characteristics typical of immiscible polymer blends and a compatibilizer agent is needed. Three different carboxyl acids: myristic (C14), palmitic (C16) and stearic acids (C18) were used as natural compatibilizer agent (NCA).

Optimized butyl butyrate synthesis catalyzed by Thermomyces lanuginosus lipase.

Butyl butyrate is an ester present in pineapple flavor, which is very important for the food and beverages industries. In this work, the optimization of the reaction of butyl butyrate synthesis catalyzed by the immobilized lipase Lipozyme TL-IM was performed. n-Hexane was selected as the most appropriate solvent.

Improved production of butyl butyrate with lipase from Thermomyces lanuginosus immobilized on styrene-divinylbenzene beads.

Two immobilized preparations from Thermomyces lanuginosus lipase (TLL) were compared in the synthesis of butyl butyrate. The commercial Lipozyme TL-IM, and TLL immobilized on styrene-divinylbenzene beads (MCI-TLL) were tested in the esterification reaction using n-hexane as solvent. The variables temperature (30-60°C), substrate molar ratio (1:1 to 5:1), added water (0-1%), and biocatalyst content (3-40%) were evaluated in terms of initial reaction rate for each biocatalyst.

Ultrasound-assisted butyl acetate synthesis catalyzed by Novozym 435: enhanced activity and operational stability.

The influence of low-frequency ultrasound (40 kHz) in the esterification reaction between acetic acid and butanol for flavor ester synthesis catalyzed by the commercial immobilized lipase B from Candida antarctica (Novozym 435) was evaluated. A central composite design and the response surface methodology were used to analyze the effects of the reaction parameters (temperature, substrate molar ratio, enzyme content and added water) and their response (yields of conversion in 2.5 h of reaction).

Immobilization of lipase B from Candida antarctica on porous styrene-divinylbenzene beads improves butyl acetate synthesis.

A new biocatalyst of lipase B from Candida antarctica (MCI-CALB) immobilized on styrene-divinylbenzene beads (MCI GEL CHP20P) was compared with the commercial Novozym 435 (immobilized lipase) in terms of their performances as biocatalysts for the esterification of acetic acid and n-butanol. The effects of experimental conditions on reaction rates differed for each biocatalyst, showing different optimal values for water content, temperature, and substrate molar ratio. MCI-CALB could be used at higher acid concentrations, up to 0.

Physiopathology of obstructive sleep apnea-hypopnea syndrome.

The physiopathology of obstructive sleep apnea syndrome is multifactorial. Gender and obesity status, as well as genetic, anatomic, and hormonal factors, together with ventilatory drive, interact in a diverse manner in the physiopathology and clinical expression of the disease. Obesity is the main risk factor, since increases in body mass index, visceral fat, and neck circumference are strong predictors of the disease.

Infection with the Mycobacterium avium complex in patients without predisposing conditions: a case report and literature review.

Nontuberculous Mycobacteria (NTM), especially Mycobacterium avium-intracellulare complex (MAC), has been considered responsible for human disease, especially in HIV patients. Nevertheless, it has been diagnosed in immunocompetent elderly men, frequently with previous pulmonary disease: chronic obstructive lung disease (COPD), complications of tuberculosis, pulmonary fibrosis and bronchiectasis. We relate the case of a female patient, 51 years old, with continuously acid fast bacilli (AFB) smears and with three previous treatments, which were conducted at the multiresistant tuberculosis (MRTB) service.