902 resultados para directed polymers in random environment
Resumo:
The use of polymeric materials has grown in recent years due to its high durability features, atoxicity, shaping versatility and environment resistance. However, while these features represent good advantages to several industry sectors, it results in one of the most serious environmental problems of contemporary society: the rising accumulation of these material, mainly due to the inadequate disposal of waste. Meanwhile, in order to minimize this problem, some mitigation techniques comes up (arises), among which the use of biodegradable polymers has been gaining attention. Because of their easily action of microorganisms, such material degrade more rapidly, becoming integrated to nature. Furthermore, due to the fact of biodegradation is a natural process, occurring through the action if micro-organisms in the environment itself, it is considered the “cleaner” alternative found so far to plastic components reincorporation in the nature. Among the micro-organisms capable of biodegradation process are the filamentous fungi. These micro-organisms have many advantages over the others, the major one being the capacity to produce a range of enzymes capable of degrading different materials. In this context, the present review made it possible to see the importance of this process as an agent of environmental preservation, suggest the use of blends to minimize the problems of cost and flexibility of biodegradable polymeric materials, as well as noting the lack of studies related to this subject nowadays
Resumo:
The pharmaceutical innovations, such as the use of polymers to control drug release, create possibilities for a better action of the drug in the body, which causes a a more effective therapeutic effect and a safer treatment for the patient. In this work, were prepared and characterized matrix tablets of hydroxypropylmethylcellulose (HPMC) containing nimesulide as model drug to evaluate the performance as a controlled release system. HPMC, a cellulose ester, is a hydrophilic polymer that undergoes swelling, i.e., absorbs water and forms a gel layer controlling drug release. The characterization of powders was performed by analysis of particle size and morphology, density, compressibility index determination, flow properties and determination of swelling profile. The tablets were evaluated according to their physical parameters of quality and to the in vitro release of nimesulide, as well as the analysis of the mechanisms of drug release by appropriate mathematical models. The set of results showed that the HPMC/Nimesulide mixture exhibited satisfactory physical characteristics (size, shape, density and flow). The release profile demonstrated an effective control upon drug release in enteric environment and presented more correlation with Korsmeyer-Peppas’ and Weibull’s mathematical models, indicating that the release of nimesulide occurs through the relaxation of the polymer chains
Resumo:
It is known that exposure to substances in the environment can contribute to various reproductive disorders, especially if such exposure occurs during critical periods of development such as the intra-uterine and postnatal. The female reproductive system may be the target of androgens, both as a result of exposure to environmental chemicals, or by pathological conditions (polycystic ovary syndrome or congenital adrenal hyperplasia).Usually, little attention is given off in relation to the study of androgenic effects in the female reproductive axis. This study aims to evaluate the effects of exposure to androgens on the development, structure and reproductive function in rats whose mothers were exposed to testosterone propionate from gestational day 12 (DG12) after weaning - postnatal day 21 (DPN21) . For this purpose, pregnancy rats were divided into four groups: a control group that received corn oil (vehicle) and three groups receiving testosterone propionate in doses of 0.05 mg / kg / day, 0.1 mg / kg / day and 0.2 mg / kg / day, all under the same experimental conditions. The possible effects of exposure were assessed using reproductive parameters, such as a measure of anogenital distance, count areolas / nipples, age at vaginal opening and first estrus (puberty indicative installation), weight and histological evaluation of the reproductive organs ( uterus and ovaries), weight of the kidneys, liver and pituitary hormone levels, regularity of the estrous cycle, sexual behavior and fertility. Such analysis is important in understanding the effects of androgen exposure on the female genital system, especially on the reproductive potential, and processes that may involve morphofunctional changes. In these experimental conditions, it is concluded that treatment with PT caused reduction in body weight and initial masculinization in females without cubs, however, commit further sexual development
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Pós-graduação em Engenharia Mecânica - FEG
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Parasitism constitutes one of the main problems that affect livestock. Commercial acaricides have been used to control tick, but these chemicals have been responsible for the development of drug resistance and residues in the environment. Changes in the concept of production determined the search for natural measures, which guarantees animal sanity along with safety of the produced food. This assay had as objective to evaluate the citronella oil and neem oil in the control of bovine ticks. By the technique of adult ticks immersion, 280 ticks were evaluated, distributed in equal number throughout four treatments: negative control group, positive control (ivermectin), neem oil and citronella oil. It was analyzed the mortality index, estimated reproduction, product efficiency, index of eggs production and the hatchability rate. The efficiency of the product was verified by the mortality index just for the positive control group (100%) and citronella oil (97.14%). Also, the citronella oil inhibited the eclosion of eggs in 100%. The other treatments did not presented the minimum eclosion inhibition level of 95%. Under the conditions of the present assay citronella oil was efficient against Rhipicephalus (Boophilus) microplus. This result was not observed in relation to the neem oil.
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Introduction: Cart horses are a re-emerging population employed to carry recyclable material in cities. Methods: Sixty-two horses were sampled in an endemic area of human leptospirosis. The microscopic agglutination test (MAT) and real-time polymerase chain reaction (qPCR) were performed. Results: A seropositivity of 75.8% with serovar Icterohaemorrhagiae in 80.8% of the horses was observed. Blood and urine were qPCR negative. MAT showed positive correlations with rainfall (p = 0.02) and flooding (p = 0.03). Conclusions: Although horses may be constantly exposed to Leptospira spp. in the environment mostly because of rainfall and flooding, no leptospiremia or leptospiruria were observed in this study.
Resumo:
The survival of infective larvae (L3) of Trichostrongylus colubriformis was evaluated on Brachiaria, Coast-cross and Aruana forage grasses. Feces of sheep parasitized exclusively by T. colubriformis were deposited in winter and spring on experimental plots whose grasses were cut at two heights: 5 cm and 30 cm. One, two, four, eight, 12 and 16 weeks after depositing the feces, fecal and forage samples were collected for the retrieval and quantification of L3. Retrieval of L3 from feces and forage was negligible in winter due to the dry weather, although a few larvae were retrieved in the last larval collections. However, L3 retrieval from fecal samples was greater in spring, especially two weeks after feces were deposited on 30 cm high grasses. At this time, the L3 retrieval rate from the three forage grasses differed significantly (P < 0.05), with Aruana grass showing the highest average L3 retrieval rate, followed by Coast-cross and Brachiaria. In conclusion, the winter drought proved very unfavorable for the presence of L3 in the environment, and the microclimate of Aruana pastureland was generally the most favorable for the retrieval of infective larvae.