Influence of the layered silicate type on the structure, morphology and properties of cellulose acetate nanocomposites

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This paper deals with the effect of different montmorillonite source clays, including pristine and organophilic montmorillonites, on the structure, morphology and properties of cellulose acetate (CA)/clay nanocomposites. In this study, the nanocomposites were prepared by melt extrusion in the presence of the environmentally friendly triethyl citrate plasticizer. The structure and morphology of the materials were analysed by X-ray diffraction and scattering (SAXS), X-ray microtomography and energy filtered transmission electron microscopy (EFTEM). SAXS and EFTEM results indicated that the nanocomposite morphologies were made up of tactoids together with exfoliated clay platelets in different proportions depending on the clay type. It can be concluded that well distributed clay tactoids and platelets can be achieved in CA nanocomposites prepared by melt extrusion and consequently property improvements can be found by using pristine or organophilic clays. In this case, the addition of a plasticizer, able to intercalate in the clay gallery, seems to be sufficient to promote the clay delamination mechanism under shearing inside the cellulose acetate matrix.202675686Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Warthin's tumour of the parotid gland: our experience

Benign tumours account for approximately 60-80% of parotid neoplasms and among these, Warthin's tumour is the second most common benign neoplasm accounting for approximately 15% of all parotid epithelial tumours. The medical records of 100 consecutive patients with Warthin's tumour of the parotid gland admitted for treatment at the Department of Head and Neck Surgery and Otorhinolaryngology, Hospital A. C. Camargo, Sao Paulo, Brazil, between 1983 and 2011 were retrospectively analyzed. The surgical procedures included 104 (96%) subtotal parotidectomies and 4 (3.7%) total parotidectomies. One hundred and eight parotidectomies were performed in 100 patients with Warthin's tumour. Postoperative complications occurred in 67 (62.3%) of surgical procedures, and facial nerve dysfunction was the most frequent complication, occurring in 51 of 108 surgeries (47.2%). The marginal mandibular branch of the facial nerve was affected in 46 of the 48 cases (95.8%) of facial nerve dysfunction. Frey's syndrome was diagnosed in the late postoperative period in 19 patients (17.6%). We conclude that either superficial or total parotidectomy with preservation of facial nerve are the treatment of choice for Warthin's tumour with no case of recurrence seen after long-term follow-up. Facial nerve dysfunction and Frey's syndrome were the main complications associated with this surgery. Thus, if on one hand total parotidectomy is an appropriate radical resection of parotid parenchyma reducing, in theory, the risk of recurrence, on the other hand superficial parotidectomy is also a radical and efficient method with lower morbidity in terms of facial nerve dysfunction and Frey's syndrome.33639339

Cationic latex formation by ionic modification

Stable cationic latices were prepared by charge inversion of anionic styrene-acrylic copolymer latices upon binding Al3+ and Fe3+ ions. This is achieved by stabilizing the latices with a high-HLB (hydrophile-lypophile balance) nonionic surfactant that imparts strong steric stability to the latex, even in the presence of high concentrations of multivalent counterions while these are bound to the latex anionic sites. The cationic latices thus prepared have good stability properties, and the same procedure should be applicable to essentially any latex-carrying anionic sites. Analytical ESI-TEM images show that particle-bound iron is concentrated at the particle borders, but it is also found in the particle bulk. (c) 2006 Elsevier Inc. All rights reserved.305225626

Schistosomal hepatopathy

Gross anatomical features and a complex set of vascular changes characterize schistosomal hepatopathy as a peculiar form of chronic liver disease, clinically known as "hepatosplenic schistosomiasis". It differs from hepatic cirrhosis, although clinical and pathological aspects may sometimes induce confusion between these two conditions. Intrahepatic portal vein obstruction and compensatory arterial hypertrophy render the hepatic parenchyma vulnerable to ischemic insult. This may lead to focal necrosis, which may give place to focal post-necrotic scars. These events are of paramount importance for the clinico-pathological evolution of schistosomal hepatopathy. Although portal fibrosis due to schistosomiasis sometimes reveals numerous myofibroblasts, it does not mean that such fibrosis belongs to a peculiar type. Damage to the muscular walls of the portal vein may be followed by dissociation of smooth muscle cells and their transition toward myofibroblasts, which appear only as transient cells in schistosomal portal fibrosis. Studies made with plastic vascular casts, especially those with the murine model of "pipestem" fibrosis have helped to reveal the mechanisms involved in systematized portal fibrosis formation. However, the factors involved in the pathogenesis of hepatosplenic disease remain poorly understood. A process of chronic hepatitis is a common accompaniment of portal fibrosis in schistosomiasis. Most of the times it is caused by concomitant viral infection. However, no especial interaction seems to exist between schistosomal hepatopathy and viral hepatitis