ESDA2006-95143 CRITICAL PENETRATION DEPTH FOR NANO/MICRO INDENTATION TEST TO DETERMINE ELASTIC-PLASTIC FILM PROPERTIES DEPOSITED ON HARD SUBSTRATES

ABSTRACT The critical indentation depth to obtain proper elasticplastic properties of thin film when the indentation tests are done on film/substrate system with sharp indenters is investigated. We focus on the characterization problem of soft film material, whose material properties are unknown, deposited on hard substrates. The critical depth is analyzed based on the finite element analysis (FEA) results. In order to extract the mechanical properties of the film from those of the film/substrate compound, we have to restrict the maximum penetration depth within a certain value. In this paper the relation between the load, P, and the depth, h, is analyzed in a power law relation, P = Ch m , where the exponent m is a function of h. From extensive FEA results, we found that this exponent m starts to depart from 2 faster with increasing indenter apex angle and increasing hardening exponent of the film material. This means that the critical indentation depth decreases with increasing indenter apex angle and increasing hardening exponent. Based on this analysis, we propose a simple formula to evaluate the critical penetration depth h 0 , as a function of apex angle, θ, of the indenter: h 0 /d = 0.243cotθ, where d is the film thickness

Subendocardial Viability Ratio Predictive Value for Cardiovascular Risk in Hypertensive Patients

Background: The subendocardial viability ratio (SEVR), also known as the Buckberg index, is a parameter of arterial stiffness with indirect prognostic value in assessing long-term cardiovascular risk. Materials and Methods: We conducted a prospective cohort study on 70 patients with uncomplicated hypertension admitted to a county medical reference hospital. We analyzed demographics, laboratory data, arterial stiffness parameters and cardiovascular risk scores (SCORE and Framingham risk scores) and aimed to identify paraclinical parameters associated with increased cardiovascular risk. Results: Of the arterial stiffness parameters, SEVR correlates statistically significantly with age, central and peripheral systolic blood pressure, as well as with heart rate. SEVR seems to have prognostic value among hypertensive patients by increasing the risk of major cardiovascular events assessed by SCORE and Framingham risk scores. SEVR correlates statistically significantly with serum fibrinogen (p = 0.02) and hemoglobin (p = 0.046). Between pulse wave velocity and lipid parameters (p = 0.021 for low-density lipoprotein cholesterol and p = 0.030 for triglycerides) a statistically significant relationship was found for the study group. The augmentation index of the aorta also correlated with serum LDL-cholesterol (p = 0.032) and the hemoglobin levels (p = 0.040) of hypertensive patients. Conclusions: Age, abdominal circumference and Framingham score are independent predictors for SEVR in our study group, further highlighting the need for early therapeutic measures to control risk factors in this category of patients