989 resultados para Handling characteristics.


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National Highway Traffic Safety Administration, Washington, D.C.

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Multifunctional bioactive materials with the ability to stimulate osteogenesis and angiogenesis of stem cells play an important role in the regeneration of bone defects. However, how to develop such biomaterials remains a significant challenge. In this study, we prepared mesoporous silica nanospheres (MSNs) with uniform sphere size (∼90 nm) and mesopores (∼2.7 nm), which could release silicon ions (Si) to stimulate the osteogenic differentiation of human bone marrow stromal cells (hBMSCs) via activating their ALP activity, bone-related gene and protein (OCN, RUNX2 and OPN) expression. Hypoxia-inducing therapeutic drug, dimethyloxaloylglycine (DMOG), was effectively loaded in the mesopores of MSNs (D-MSNs). The sustained release of DMOG from D-MSNs could stabilize HIF-1α and further stimulated the angiogenic differentiation of hBMSCs as indicated by the enhanced VEGF secretion and protein expression. Our study revealed that D-MSNs could combine the stimulatory effect on both osteogenic and angiogenic activity of hBMSCs. The potential mechanism of D-MSN-stimulated osteogenesis and angiogenesis was further elucidated by the supplementation of cell culture medium with pure Si ions and DMOG. Considering the easy handling characteristics of nanospheres, the prepared D-MSNs may be applied in the forms of injectable spheres for minimally invasive surgery, or MSNs/polymer composite scaffolds for bone defect repair. The concept of delivering both stimulatory ions and functional drugs may offer a new strategy to construct a multifunctional biomaterial system for bone tissue regeneration.

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Venous ulcer (VU) is a lower limbs injury resulting from inadequate return of venous blood in feet or legs. Although it is not a deadly disease, it causes chronic wounds, which seriously undermine patients´ quality of life (QOL) and sometimes leads to drastic family, social, economic and psychological changes. In this sense, there are several aspects that may influence the venous ulcers patients´ QOL. The study´s objective aimed on the association of socio-demographic and health, health care and clinical injury on UV patients‟ QOL. Analytical studies, which consider the complexity of factors involved in changes in UV patients‟ QOL has a cross-sectional and quantitative approach. The HUOL Ethics Committee approved this project (n.279/09). The collection of data lasted a period of 3 months in 2010 and it took place at the clinic of Angiology at Hospital Universitário Onofre Lopes (HUOL). The data sample consisted of 60 patients treated by UV angiologists in the HUOL Surgical Clinic. The results were analyzed with SPSS 15.0 by descriptive and inferential statistics. The study was based on UV patients that were predominantly female, average age of 61.4 years, that had low education level and low family income, with occupations requiring long periods of standing or sitting, but mostly retired, unemployed or laid off due to the disease and/or due to chronic diseases associated with the UV. The study took also into consideration patients that used inappropriate products, that were improperly treated by a professional caregiver, that lacked of adequate guidance and compression therapy, that performed no lifting of the lower limbs and regular exercise, that the time of injury were greater than or equal to six months, that were missing specific laboratory tests. The study‟s reference were on recurrent lesions, medium to large lesions area, bed of the lesion (injuries) with fibrin and/or necrosis, with amount of exudate with medium to large, odorless and no signs of infection, with tissue loss between 1st and 2nd degree, without collecting swab or biopsy and with pain. In general, QOL of researched individuals were considered low, the maximum score was 69 points, which the areas that were mostly influenced were the total scores of QOL functional capacity (0.021), emotional (0.000) and social functioning (0.080). Of the 60 individuals, 53.3% had scores between 40 and 69 points in SF-36, and they had the best scores in sociodemographic and health variables (ρ = 0.049). In respect to the assistance and injury characteristics, patients who scored between 40 and 69 points in SF-36 had better scores on these characteristics. By combining the socio-demographic variables, health, and handling characteristics of the injury, we observed a significant difference (ρ = 0.032) when linking them with the QOL total scores. When analyzing separately the domains of the SF-36 scores on the quality of life, we find that the areas that showed statistical significance were functional ability (ρ = 0.035), appearance (ρ = 0.019), emotional (ρ = 0.000), and mental health (ρ = 0.050). Among the socio-demographic characteristics studied, gender and marital status contributed more to the reduction of QOL and among the variables of assistance and the injury, orientation, reference and area of UV contributed the most. By analyzing these five variables all together in accordance with the overall score obtained in the quality of life, we found a significant correlation (ρ = 0.002); with 6.23 times more chances of patients have better QOL in the presence of these five positive factors. By conducting the Mann Whitney U test between all the five demographic variables, health, and clinical care, we found that this combination also proved to be significant (ρ = 0.006). Therefore, patients with these five variables positive tend to have a better QOL. Based on these results, we reject the null hypothesis (H0) and accept the alternative hypothesis (H1) proposed in this study because we noted that the QOL of patients with UV is associated with sociodemographic and health, health care and clinical aspects of the injury

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This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and influence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classifed according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-and-rinse systems require a specifc acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and defciencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplifed ones due to some chemical associations and interactions. The SEM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions.

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Pós-graduação em Medicina Veterinária - FCAV

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Objective: This study evaluated the 56-month clinical performance of Class I and II resin composite restorations. Filtek P60 was compared with Filtek Z250, which are both indicated for posterior restorations but differ in terms of handling characteristics. The null hypothesis tested was that there is no difference in the clinical performance of the two resin composites in posterior teeth. Material and Methods: Thirty-three patients were treated by the same operator, who prepared 48 Class I and 42 Class II cavities, which were restored with Single Bond/Filtek Z250 or Single Bond/Filtek P60 restorative systems. Restorations were evaluated by two independent examiners at baseline and after 56 months, using the modified USPHS criteria. Data were analyzed statistically using Chi-square and Fisher's Exact tests (alpha=0.05). Results: After 56 months, 25 patients (31 Class I and 36 Class II) were analyzed. A 3% failure rate occurred due to secondary caries and excessive loss of anatomic form for P60. For both restorative systems, there were no significant differences in secondary caries and postoperative sensitivity. However, significant changes were observed with respect to anatomic form, marginal discoloration, and marginal adaptation. Significant decreases in surface texture were observed exclusively for the Z250 restorations. Conclusions: Both restorative systems can be used for posterior restorations and can be expected to perform well in the oral environment.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Vehicle Engineering Research Division, Washington, D.C.

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National Highway Traffic Safety Administration, Vehicle Engineering Research Division, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Crash Avoidance Research Division, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Washington, D.C.