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- ItemAcesso aberto (Open Access)Avaliação do efeito da massa molar na quaternização da quitosana e nas propriedades dos filmes de quitosana quaternizada(Universidade Federal de São Paulo, 2023-07-31) Faria, Danielle Bitencourt [UNIFESP]; Moraes, Mariana Agostini de [UNIFESP]; Silva, Classius Ferreira da [UNIFESP]; http://lattes.cnpq.br/4514485329529047; http://lattes.cnpq.br/0644374691728856; https://lattes.cnpq.br/4567597606259744A quitosana é um polissacarídeo biocompatível, biodegradável e biofuncional. Entretanto, a maioria das quitosanas comerciais e desenvolvidas em laboratórios de pesquisa são solúveis apenas em pHs ácidos, o que motivou o desenvolvimento de modificações químicas, tais como a quaternização, que tornam a quitosana solúvel em todas as faixas de pH e expandem seu campo de aplicação. O processo de quaternização mais comum é o de N-alquilação, a partir do qual obtém-se o composto Cloreto de N-(2-hidroxi)-propril-3-trimetilamônio quitosana (HTCC), que é amplamente utilizado em aplicações biológicas e farmacêuticas. Sabe-se que as propriedades da quitosana são influenciadas diretamente pela massa molar e grau de desacetilação. No entanto, a literatura carece de estudos que analisem a influência da massa molar da quitosana no processo de quaternização e nas propriedades dos filmes obtidos a partir da quitosana quaternizada, sendo este o objetivo do presente estudo. Os resultados obtidos indicaram que o aumento da massa molar da quitosana resulta no aumento do grau de quaternização, possivelmente devido à maior disponibilidade para reação dos grupos amino presentes na molécula de quitosana. Além disso, os filmes de quitosana quaternizada foram preparados por casting e analisados quanto às suas propriedades físico-químicas e biológicas. Os filmes de quitosana quaternizada apresentaram comportamento elastomérico, com deformação na ruptura variando de 73 a 102%, valor 74% maior, em média, do que os filmes de quitosana. Além disso, os filmes de quitosana quaternizada apresentaram excelente atividade antimicrobiana, com halos de inibição de S. aureus e E. coli variando de 30 a 36 mm. Desta forma, é possível concluir que a massa molar é um fator preponderante que deve ser considerado na análise de reações de quaternização da quitosana e que os filmes de quitosana quaternizada são uma excelente opção para aplicações que exijam grande elasticidade e controle do crescimento microbiano, abrangendo desde a área de embalagens e recobrimentos até a área médico-farmacêutica.
- ItemAcesso aberto (Open Access)Comparação das medidas instrumentais não invasivas e parâmetros clínicos entre o envelhecimento intrínseco e o fotoenvelhecimento da pele dos antebraços(Universidade Federal de São Paulo (UNIFESP), 2017-04-28) Carvalho, Paula Roberta Silva de [UNIFESP]; Bagatin, Edileia [UNIFESP]; http://lattes.cnpq.br/6478900066830476; http://lattes.cnpq.br/5342802165966201; Universidade Federal de São Paulo (UNIFESP)Background: The intrinsic and extrinsic skin aging present biomechanical and morphological differences, which are reflected in the appearance of roughness, superficial and deep wrinkles, atrophy, reduced elasticity, hypo- and hyperpigmentation and actinic keratosis. The photodamage causes accentuation of all these features and increases the risk for development of premalignant lesions (actinic keratosis) and malignant (basal and squamous cell carcinomas). Objective: to evaluate and compare the characteristics of the flexor (with a predominance of intrinsic aging) and extensor (chronically exposed to sunlight area and other environmental factors, with a predominance of extrinsic aging or photoaging) skin surfaces of the forearms. Methods: The cross-sectional study of diagnostic interventions, including 23 females, aged over 60 years. The extensor and flexor faces of right and left forearms were compared in relation to clinical parameters and non-invasive instrumental measures, such as: skin surface (profilometry), viscoelastic properties, hydration (corneometry) as well as dermal thickness and echogenicity (ultrasound). Results: The water content in the corneal layer showed a significant difference as the flexor area showed an average value greater than the extensor face. The average of the measurements obtained by high-frequency ultrasound showed difference between the faces. The skin surface measurements showed significant differences when compared roughness and desquamation of the extensor and flexor faces on both forearms, but for the flexor face, the differences were smaller. Regarding the wrinkles depth, there was a significant difference of average between the evaluated faces only for the left forearm (p = 0.017), once the flexor face presented an average value greater than the extensor. There was no significant correlation between measurements of the aqueous content of the corneal layer and the viscoelastic properties of the skin, as well as among those obtained by ultrasound. In the prophylometry, only the scaling presented a negative correlation with the corneometry. The visco-elastic properties of the skin showed a positive correlation between the faces. The measurements obtained by the ultrasound and the visco-elastic properties of the skin showed a positive correlation in the flexor face. In the extensor face, there was a positive correlation between roughness, scaliness and wrinkle depth. In the flexor face, the depth of the wrinkles presented negative correlation with a dermal thickness. Dermal density showed negative correlation with other ultrasound measurements. These results were in agreement with established clinical parameters such as wrinkles, elastosis, decreased elasticity and water content, demonstrating the differences between photoaging and chronological aging. Conclusion: Significant differences in the biophysical characteristics of the extensor and flexor surfaces of the forearms were detected. The non-invasive instrumental measures were positively correlated with clinical findings. We concluded that they are useful tools for the evaluation of photoaging and chronological aging in clinical research, as efficacy and safety parameters.
- ItemAcesso aberto (Open Access)Efeitos imediatos de um esforço submáximo sobre a velocidade de onda de pulso em pacientes com Síndrome de Marfan(Universidade Federal de São Paulo (UNIFESP), 2010-05-26) Peres, Paulo Alberto Tayar [UNIFESP]; Carvalho, Antonio Carlos [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Purpose: Marfan syndrome is a dominant autosomal disease provoked by mutations of gene of fibrillin 1, chromosome 15, and may exhibit skeletal, ocular, cardiovascular and other manifestations. Pulse wave velocity (PWV) is used as a measure of arterial elasticity and rigidity and is related to the elastic properties of the vascular wall. As the practice of exercise is limited in this population, it was of our interest to analyze the acute effect of moderate to intensive exercise on patients with Marfan syndrome with either no dilatation of the aorta or a maximum of mild dilatation of this vessel. Methods: PWV and physiological variables were evaluated before and after the performance of sub-maximal exercise in 33 patients with Marfan syndrome and 18 controls. Results: PWV in the group with Marfan syndrome was 8.51±0.58 m/s at rest and 9.10±0.63 m/s at the end of the exercise (p=0.002); in the control group, PWV was 8.07±0.35 m/s at rest and 8.98±0.56 m/s at the end of exercise (p=0.004). The comparative analysis between groups regarding PWV at rest (p=0.519) and at the end of exercise (p=0.866) revealed no statistically significant differences. The final heart rate values in the control group were 10% higher than values in the group with Marfan syndrome (p = 0.01). Final systolic arterial pressure was higher in the control group (p=0.02). There was no difference in lactate between groups. Exercise time was greater in the control group (p=0.01). Conclusions: The behavior of aortic distensibility was similar in the patients with Marfan syndrome without or with mild dilatation of the aorta to that of the control group. The chronotropic and pressure responses were lower in patients than in control group.
- ItemAcesso aberto (Open Access)Viabilidade da medida da velocidade de propagação sonora em tecidos oculares in vivo e sua correlação com a elasticidade presumida(Universidade Federal de São Paulo (UNIFESP), 2016-07-08) Ribeiro, Joao Crispim Moraes Lima [UNIFESP]; Allemann, Norma [UNIFESP]; http://lattes.cnpq.br/0956596522261307; http://lattes.cnpq.br/5238824885154872; Universidade Federal de São Paulo (UNIFESP)Introduction: To date, it has never been demonstrated the propagation speed of sound in human corneas and lens in vivo. With the advent of Optical Coherence Tomography (OCT), it became possible to determine the dimensions of the ocular tissues without the interference of sound propagation speed and to use this information to define the real propagation speed of sound for each patient and individualized structure. Purpose: To determine the speed of sound in the cornea and lens from groups of patients that theoretically exhibits differences in tissue elasticity and to correlate the determined velocity in each group with the expected tissue elasticity of the cornea and lens. Methods: We studied 100 eyes from 50 patients: 50 young (less than 40 yearsold) with keratoconus and no cataract (Group 1) and 50 elderly (more than 50 years-old) with cataracts and no corneal changes (Group 2). All patients had their corneas and lenses thicknesses measured by ultrasonographic methods: UBM - Ultrasound Biomicroscopy, Vumax II®, and UP - Ultrasonic Pachymetry, Pachette 2 model DGH 550®, as well as by optic methods: OCT (RTVue®, Lenstar® and Visante®). Corneal central thickness was evaluated by UBM, USP, RTVue®, Visante®, and Lenstar®. Axial thickness of the lens was evaluated by UBM and Lenstar®. Based on standard ultrasonic speed used in UP (1640 m/s) and UBM (1548 m/s), we calculated the real sound propagation speed in each tissue. Results: Based on UP, the mean corneal speed of sound on Group 2 (1611 m/s) was faster than on Group 1 (1571 m/s) (P < 0.05). Based on UBM, the mean lens speed of sound on Group 2 (1662 m/s) was faster than on Group 1 (1602 m/s) (P < 0.0001). Discussion: It is known that sound propagates faster in materials with lower elasticity. We found that the speed of sound on keratoconic corneas (high elasticity) was slower and on cataract lens (lower elasticity) was faster than normal corneas and lens in vivo.