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Search Results: 1 - 10 of 282313 matches for " Maria Elisa Scarpelli Ribeiro e Silva "
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Bioartificial polymeric materials based on collagen and poly(N-isopropylacrylamide)
Mano, Valdir;Ribeiro e Silva, Maria Elisa Scarpelli;
Materials Research , 2007, DOI: 10.1590/S1516-14392007000200012
Abstract: films of collagen (clg) and poly(n-isopropylacrylamide), pnipaam, were prepared by casting from water solutions. these bioartificial polymeric materials were studied to examine the influence of pnipaam content and glutaraldehyde vapor cross-linking on the thermal and biological stability of clg. mixtures, ranging from 20-80 wt% clg composition, were cross-linked through exposure to glutaraldehyde vapors. thermal and morphological properties of the films, cross-linked or not, were investigated by differential scanning calorimetry, thermogravimetry, and scanning electron microscopy, with the aim of evaluating miscibility, thermal stability, and interactions among the constituents. the experimental results indicated that the homopolymers are not thermodynamically compatible. however, there is good evidence that effective interactions, probably due to hydrogen bond formation, takes place between the constituents. these interactions are more evident on the samples that were not cross-linked. dsc studies revealed that pnipaam exerts a thermal stabilizing effect on uncross-linked clg, while the cross-linking with glutaraldehyde affects only the biological polymer, preventing the interactions with pnipaam. sem micrographs of the uncross-linked mixtures showed that the morphology, in all compositions studied, remains similar to the pure collagen. in the corresponding cross-linked samples, a more compact aggregation is observed although no appreciably changes can be seen.
Synthesis, Characterization, and Study of PLGA Copolymer in Vitro Degradation  [PDF]
Anamaria Teodora Coêlho Rios Silva, Barbara Camilla Oliveira Cardoso, Maria Elisa Scarpelli Ribeiro e Silva, Roberto Fernando Souza Freitas, Ricardo Geraldo Sousa
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2015, DOI: 10.4236/jbnb.2015.61002
Abstract: The poly(lactic-co-glycolic acid), known as PLGA, is one of the main bioreabsorbable polymers used in the field of medicine today. This copolymer is widely applied in sutures, devices geared toward the controlled release of medication, and the guided regeneration of bone tissue as it presents a short degradation time. This work aimed to synthesize the 82/18 PLGA (expressed by the mass ratio of D,L-lactide and glycolide, respectively), to characterize and study the in Vitro degradation in the form of rods in phosphate buffer solution (PBS). The copolymer was synthesized by opening the cyclic dimer rings of the monomers D,L-lactide and glycolide, in the presence of the tin octanoate initiator and of the lauryl alcohol co-initiator. The characterization of the copolymer and the follow-up of its in vitro degradation were studied using: Differential Scanning Calorimetry (DSC), Thermogravimetry (TG), Infrared Molecular Absorption Spectroscopy with Fourier Transform (FTIR), Rheometry, and Scanning Electron Microscopy (SEM). Through these characterization techniques, it was possible to obtain the glass transition temperature, thermal stability, chemical composition, morphology, and molar mass of both the synthesized and the degraded copolymer. The molar mass of the synthesized copolymer was, approximately, 106 g·mol-1. The degradation rate of PLGA significantly increased from the 19th to the 28th day in PBS. After 28 days in PBS, the glass transition temperature and the molar mass reduced from 45°C to 17°C and from 1.5 × 106 g·mol-1 to 7.5 × 10g·mol
Rheological and Thermal Behavior of High-Density Polyethylene (HDPE) at Different Temperatures  [PDF]
Cynthia D’Avila Carvalho Erbetta, Getúlio F. Manoel, Ana Paula Lelis Rodrigues Oliveira, Maria Elisa Scarpelli Ribeiro e Silva, Roberto Fernando Souza Freitas, Ricardo Geraldo Sousa
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.513094
Abstract: In the present work, rheological properties of HDPE samples were measured at temperatures of 150°C, 190°C and 230°C. It was shown, by oscillatory tests, at low frequencies, that, for temperatures of 150°C and 190°C, there was a predominance of the viscous behavior over the elastic one. At 230°C, there was a predominance of the elastic contribution, and there was an increase of the molar mass compared with the ones obtained from the tests at 150°C and 190°C. The results obtained from the temperature ramp oscillatory test showed that, up to around 248°C, the viscous behavior prevailed, the opposite being observed at higher temperatures. At 230°C the sample showed significantly lower values of strain when compared with the ones observed at 150°C and 190°C. Oxidative induction time (OIT), melting point and degree of crystallinity were determined by differential scanning calorimetry (DSC). The DSC results and the rheological measurements showed a completely different behavior for the HDPE samples at 230°C compared with the 150°C and the 190°C ones, suggesting that HDPE, at the temperature of 230°C, underwent thermo-oxidative degradation with the initial predominance of crosslinking.
Rheological Study of Polymers Used as Viscosity Index Improvers for Automotive Lubricant Oils  [PDF]
Ana Paula Pena Almeida, Ana Paula Lelis Rodrigues de Oliveira, Cynthia D’ávila Carvalho Erbetta, Ricardo Geraldo de Sousa, Roberto Fernando de Souza Freitas, Maria Elisa Scarpelli Ribeiro e Silva
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.512110

In this work, a rheological study of automotive lubricant oils, neutral light paraffinic (NLP) and neutral medium paraffinic (NMP), additivated with two commercial viscosity index improvers-VIIs, based on hydrogenated poly (isoprene-co-styrene), at different concentrations, was carried out. The study included the determination of the kinematic viscosity of the mixtures, the calculation of the viscosity indexes and their behavior when subjected to various rheometric experiments, including stress sweep, steady state flow, creep and recovery, and temperature ramp oscillatory tests. The obtained results showed the efficacy of the additives as viscosity index improvers, enabling a significant increase in the viscosity index of the pure oils at relatively low concentrations. The determination of the storage (G’) and of the loss (G”) moduli for the mixtures oil/VII additives showed a large predominance of the viscous effect over the elastic one. Except when under low shear stress, the mixtures showed a pseudoplastic behavior, with the flow curves being adjusted to fit the Ostwald-de-Waele model (Power Law), with negative flow behavior indexes.

Síntese e caracteriza??o do copolímero poli(3-hidroxibutirato-co-ε-caprolactona) a partir de poli (3-hidroxibutirato) e poli(ε-caprolactona)
Roa, Juan P. B.;Mano, Valdir;Faustino, Patrícia B.;Felix, Eduardo B.;Silva, Maria Elisa S. Ribeiro e;Souza Filho, José D.;
Polímeros , 2010, DOI: 10.1590/S0104-14282010005000038
Abstract: in the present work, the copolymer poly(3-hydroxybutyrate-co-ε-caprolactone), p(hb-co-cl), was prepared by transesterification reaction from phb and pcl. zirconium (iv) acetylacetonate was used as catalyst and the copolymers were obtained in a wide range of compositions of phb/pcl (20/80, 50/50, 80/20). these copolymers were characterized by gpc, ft-ir, 1h-nmr, 13c-nmr, tg, and dsc. the copolymers had weight average molecular weight less than 24.000 daltons. all the systems were thermally more stable than phb, showing lower crystallinity than the homopolymers. these materials are good candidates to be used as biomaterials, in drug release matrices, or even as phb/pcl blends compatibilizers.
Rela??o entre enfermeiros e médicos no Hospital das Clínicas da Universidade Federal de Goiás: a perspectiva do profissional de enfermagem
de Oliveira,Ana Maria; Moreira Lemes,André; Teixeira ávila,Bruna; Rocha Machado,Carolina; Ordones,Elisa; Souza Miranda,Fernanda; Loyola e Silva,Fernanda; Soares Goetz,Hermann; Ferreira de Miranda,José Oscar; Moreira Barbosa,Juliane; Ribeiro Le?o,Lahis;
Revista Latinoamericana de Bioética , 2010,
Abstract: the conflict in the relationship between doctors and nurses is a taboo subject in the health service and little discussed in the literature. it is known that the conflict between these classes, that are directly responsible for the care of the patient, is caused by the combination of diverse factors ranging from the establishment of the group of work until the salary. the research presented here aimed to verify if there is conflict in the relationship between doctors and nurses at the clinical hospital of the federal university of goiás (hc) and the factors that may promote or prevent it. an amount of 82 nurses were interviewed to study this population and the categories of variables that interfere in their relationship with other professionals. the result was a population with a prevalence of females (89%) with mean age of 40.5 years, average working time at the hc of 11 years and with weekly working hours average of 30. factor analysis identified three protective factors (division of tasks, teaching hospital and influences in the patient) and three other conflict generator factors (communication, recognition and working conditions), while the conflict underlies the processes related to work and personal relationship. the patient is the primary beneficiary when there is a good relation. bad communication, non-appropriate working conditions and unworthy remuneration are destabilizing factors for the inter-professional relationship.
Adenosina e neuroprote??o na epilepsia do lobo temporal: da ativa??o do receptor A1 ao bloqueio do receptor A2A
Rosim, Fernanda Elisa;Silva, Iara Ribeiro;Persike, Daniele Suzete;Vignoli, Thiago;Fernandes, Maria José da Silva;
Journal of Epilepsy and Clinical Neurophysiology , 2010, DOI: 10.1590/S1676-26492010000200005
Abstract: objective: to characterize the effect of the a2a receptor blockage by the sch58261 in the seizure modulation and neuroprotection of the brain areas vulnerable to injury by pilocarpine. the effect of sch58261 was also analyzed in combination with the activation of the a1 receptors by r-pia. methods: eight groups were studied: pilo, sch+pilo, r-pia+pilo, r-pia+sch+pilo, and respective controls. the number of animals in status epilepticus (se), the latency to the se onset and the mortality rate were evaluated. the fluoro jade b (fjb) method was performed 24 hours and seven days after se. results: the pretreatment with sch58261, r-pia and r-pia+sch58261 reduced the number of animals in se, increased the latency to the se and decreased the mortality rate, compared to pilocarpine treatment. the r-pia and r-pia+sch58261 groups exhibited a reduction in the number of fjb stained cells in ca3 and hilus, 24 hours and seven days after se, and in the piriform cortex only 24 hours after se, compared to pilo group. conclusion: the a2a antagonist demonstrated a potent anticonvulsant effect, while the a1 agonist had a crucial role in the seizure modulation and promoted significant neuroprotection.
Characterization and Lifetime Estimation of High Density Polyethylene Containing a Prodegradant Agent  [PDF]
Cynthia D. C. Erbetta, Raquel C. S. Azevedo, Karen S. Andrade, Maria Elisa S. R. e Silva, Roberto F. S. Freitas, Ricardo G. Sousa
Materials Sciences and Applications (MSA) , 2017, DOI: 10.4236/msa.2017.813072
Abstract: High density polyethylene (HDPE) samples, containing different concentrations of prodegradant additive d2w, were prepared. The properties of the samples were evaluated through differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), rheometry, and scanning electron microscopy (SEM). The work contributes to decreasing the products made of non-biodegradable polymeric materials derived from fossil sources which are have become a problem due to their increasingly inappropriate disposal and long degradation time in the environment. The obtained results indicated that there was no degradation of the samples due to processing. No significant changes in melting temperature, crystallinity, viscoelastic behavior, molecular weight and chemical composition were observed. Images from SEM analysis showed particles on HDPE surface, attributed to prodegradant additive d2w. Oxidation Onset Temperature (OOT) results showed that the additive d2w accelerated the degradation of HDPE. The activation energy (Ea) was determined by Ozawa-Wall-Flynn method. The obtained values were used for lifetime estimation of the samples. At 25°C, HDPE with d2w showed a lifetime 50% higher than that of HDPE without this additive. This fact is attributed to the presence of stabilizers in masterbatch d2w and the absence of oxygen in thermogravimetric analysis.
Flora bacteriana da cavidade oral, presas e veneno de Bothrops jararaca: possível fonte de infec??o no local da picada
Jorge, Miguel Tanús;Mendon?a, Jo?o Silva de;Ribeiro, Lindioneza Adriano;Silva, Maria Lucia Ribeiro da;Kusano, Elisa Junko Ura;Cordeiro, Carmen Lúcia dos Santos;
Revista do Instituto de Medicina Tropical de S?o Paulo , 1990, DOI: 10.1590/S0036-46651990000100002
Abstract: culture of fang, fang sheath and venom of fifteen healthy freshly captured bothrops jararaca were analised. the bacteria most frequently encountered were group d streptococci (12 snakes), enterobacter sp. (6), providencia rettgeri (6), providencia sp. (4), escherichia coli (4), morganella morganii (3) and clostridium sp. (5). the bacteria observed are similar to those found in the abscesses from bothrops bitten patients. since these snake mouth bacteria may be inoculated during the snake bite, bacterial multiplication and infection may occur under favorable conditions.
A pilot study of topiramate in children with Lennox-Gastaut syndrome
Arquivos de Neuro-Psiquiatria , 1999,
Abstract: We conducted an open, add-on study with topiramate (TPM) as adjunctive therapy in Lennox-Gastaut syndrome (LGS), to assess the long-term efficacy and safety and to evaluate quality of life (QL) measurements in the chronic use of TPM. We studied 19 patients (11 male; age ranging from 4 to 14 years) with uncontrolled seizures receiving 2-3 anti-epileptic drugs. Patients were followed up to 36 months of treatment. A questionnaire was used to query parents about QL. Seven patients completed the study at 36 months and seizure frequency was reduced > 75% in 4, and < 50% in 3 patients. Two children became seizure free for more than 24 months. Most side effects were CNS related, with the most frequent being somnolence and anorexia. These were generally transient. One patient dropped-out due to powder in the urine. None of the patients required hospitalization. At 36 months, patients' alertness (2/7), interaction with environment (5/7), ability to perform daily activities (5/7), and verbal performance (6/7) improved on TPM. We conclude that TPM may be useful as adjunctive therapy in the treatment of LGS. The efficacy of TPM was maintained in long-term treatment in more than 40% of patients, long term safety was confirmed and QL improved on TPM.
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