140 research outputs found
Delamination localisation and length estimation in composite laminate beam by VSHM and pattern recognition methods
No full textThe focus of this work is to investigate the delamination damage in laminate composite beams, to fix a Vibration-based structural health monitoring (VSHM) method for the laminate structures. The analysis is concentrated on the vibration characteristics of the samples and, in particular, the attention is addressed on the first several natural frequencies of a composite laminate beam with a delamination damage. The core of this work is an experimental investigation on the vibration response of a composite laminate beam and its changes caused by delaminations with different sizes and in different locations of the beam. The study is divided in 3 sections: delamination detection, delamination localization, and delamination estimate. The aim is to determine how the first six harmonics frequencies change due to the delamination, and the results show that they can be successfully used to investigate the presence, the location and the dimensions of the delamination in a composite beam. A Pattern Recognition analysis is used to locate the damage, while the detection and the evaluation are done using the changes in the harmonic frequencies. A finite element analysis is performed, and the variations of the natural frequencies due to delamination are in good agreement with the experimental results
Serum thyroglobulin measurement: clinical background and main methodological aspects with clinical impact
No full textIt is worldwide recognized that circulating thyroglobulin (Tg) measurement represents a fundamental tool in the follow-up of patients affected by differentiated thyroid cancer (DTC). In the last American and European Consensus Conferences, a surveillance guideline has been extended to the use of thyrotropin (TSH)-stimulated Tg levels for thyroidectomized patients without clinical evidence of residual tumor with Tg below 1 microg/l during TSH suppression. Therefore, sensitivity of the methods is critical to detect small amounts of Tg and/or to observe minimal changes in Tg concentration in the management of DTC patients. It has been proposed that only methods providing the greatest distinction between the lower limit of euthyroid reference range (approximately 3.0 microg/l) and the functional sensitivity limit (at least 1 microg/l) of the assay may offer a suitable clinical sensitivity for detecting small amounts of functioning thyroid tissue in TSH-suppressed state (1 g of normal thyroid tissue results in a serum Tg of approximately 1 microg/l when TSH is normal and about 0.5 microg/l when TSH is suppressed). In the last 30 years sensitivity of Tg measurements has been greatly improved, nowadays methods can achieve very good analytical and functional sensitivity to give reliable results also in the very low concentration range (between 0.1 and 1 microg/l). In addition, with the introduction of fully automated assays, results can be readily available to the clinician while patients are still in the ambulatory area. However, despite the large clinical use of Tg measurement, wide differences (by threefold) still remain between results produced in different laboratories due to poor standardization, heterogeneity of circulating Tg, interference from auto-antibodies, differences in the epitope recognition by antibodies used in the assay
Comparison between BNP values measured in capillary blood samples with a POCT method and those measured in plasma venous samples with an automated platform
No full textLetter to the Editor. Our data suggest that it is possible
to measure BNP in fresh finger-stick samples of capillary
whole blood with an acceptable reproducibility,
and within 10 – 20 min to obtain results close correlated
to those measured by the automated platform in plasma
blood samples collected from a vein. The measurement
of BNP in fresh finger-stick samples of capillary whole
blood with this POCT method is in particular indicated for
the management of HF patients at home and for the BNP
assay in neonates and children
An integrated approach based on acoustic emission and mechanical information to evaluate the delamination fracture toughness at mode I in composite laminate
No full texthis paper addresses a new method based on the combination of mechanical behavior and acoustic emission (AE) information of composite materials during mode I delamination. The method is based on a special purpose function, called sentry function, which is defined as the logarithm of the ratio between mechanical energy and acoustic energy (f=Ln(Es/Ea)). The sentry function is used to study the delamination process and to evaluate the delamination fracture toughness in mode I. The relationship between cumulative fracture toughness energy release rate (GI) and the integral of the sentry function during crack propagation showed a transition point with two sensitive regions below and above it. This behavior can be followed to obtain the critical strain energy release rate value (GIc). Results obtained by means of the sentry function are compared with results obtained by a methodology proposed by other author
Analytical performance of CA 19.9, CA 125, and CA 15.3 assays as observed through an external quality assessment program
No full text Immunoassays of the tumor markers CA 19.9, CA125 and CA 15.3 are generally acknowledged to be a useful tool in the management of cancer patients. As a consequence, many methods developed by different companies are now commercially available. However, discrepancies have been described in the results of marker determinations even when the same monoclonal antibody was used. An external quality assessment (EQA) was carried out; starting from 1989 about 110 laboratories participated; since December 1991 the program was linked with the interlaboratory program Oncocheck organized by the Service de Radiopharmacie et Radioanalyse, University of Lyon. At present more than 200 laboratories of many European countries are involved: cumulatively 47 quality control samples have been prepared and sent to the participants. This manuscript is a report on data collected for CA 19.9, CA 125, and CA 15.3. </jats:p
External quality assurance of the carcinoembryonic antigen (CEA) assay: main findings in six years' experience
No full textIn 1984 we initiated a national external quality assessment (EQA) program (supported by the Italian National Research Council, CNR) for the CEA assay; at present, about 200 Italian laboratories are participating in the program. The laboratories assayed the quality control (QC) samples according to their routine procedures and returned the results together with the name of the method/kit they used. The collected results were computer-processed and reports were sent back to the participants. A significant reduction of the CVt (mean between-laboratory agreement) of the CEA assay was observed throughout the EQA survey (from 35% in 1985 to 20-25% in the last cycles). In order to better clarify the differences in variability observed in the first QC cycles against the last ones, we used the ANOVA technique to evaluate the components of variability. The improvement in between-laboratory agreement was mainly due to the reduction of the between-kit component (from 30.5% to 15.2%), rather than to the smaller decrease observed for the within-kit variability (from 18.4% to 14.0%). The results reported for QC samples from different materials showed differences in the between-lab variability and substantial changes of the kit biases, thus suggesting a different specificity of the antibodies used in the various method/kits against different families of CEA molecules. Considerable uncertainty was also encountered in the clinical classification of low pathological samples, which seems mainly due to the variability in cut-off values used by the laboratories for the clinical assessment of the same analytical results. Our data indicate a progressive increase in the reliability of CEA determination during our study and confirm that EQA has improved the reliability of analysis carried out by the participating laboratories, thus stimulating the kit manufacturers to provide more reliable products
Valutazione delle caratteristiche analitiche di un nuovo metodo di dosaggio del BNP
No full textEvaluation of the analytical characteristics of a new method for determination of BNP.
Recent studies demonstrated that there are marked differences in analytical performances and results obtained with different methods for BNP assay. The aim of this study is to evaluate the analytic performance and results obtained with a novel BNP assay using the platform AIA 2000 Tosoh Bioscience. The novel method for BNP
tested in the present study, named ST AIA-PACK BNP, is a two-site immunoenzymometric assay. The BNP assay uses a combination of two monoclonal antibodies and a fluorescent detection. The limits of blank (LoB) and detection (LoD) for BNP assay were determined according to the CLSI EP17-A protocol. As a result, the calculated LoB and LoD values were 2.6 ng/L and 5.4 ng/L, respectively. The assay reproducibility was evaluated in accordance with the CLSI EP5-A2
protocol by repeatedly measuring 3 different EDTA plasma samples for consecutive 20 working days, containing on average 8.70 ng/L, 21.72 ng/L, and 38.72 ng/L of BNP, respectively; CV values between 19.4% and 5.0% were obtained. The between-runs imprecision profile was performed by repeatedly measuring in 20 different runs 9 EDTA blood sample, with concentration from 5 ng/L to 778 ng/L, collected from healthy subjects and patients with cardiac disease. The calculated limits of quantitation (LoQ) at 20% CV and 10% CV were 9 and 30 ng/L of BNP, respectively. The results obtained with the new BNP Tosoh method was compared with those found with the TRIAGE Beckman-Coulter. A very close linear regression was found when the BNP values were measured with Tosoh and Beckman-Coulter methods in 133 EDTA plasma samples of healthy subjects and cardiac patients. However the Tosoh method showed on average a significant negative bias (i.e., underestimation) of BNP values compared to Beckman-Coulter of -40.0%±8.8% (mean±SD, p<0.0001). A significant correlation was also found between the BNP and NT-proBNP values, respectively measured with AIA Tosoh and ECLIA Roche methods, although weaker than that obtained comparing the two BNP assays. These data suggest that the ST AIA-PACK BNP assay has reproducibility and analytic sensitivity similar to the common automated methods commercially available at present time. In particular, the AIA method measures the recommended cut-off (i.e., 100 ng/L) by international guidelines with an imprecision less than 5%. These data also suggest that clinicians should be carefull when comparing results from different laboratories, which use different BNP
assays
Valutazione esterna di qualità dei peptidi natriuretici BNP e NT-proBNP: risultati del programma Cardio-Ormocheck.
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