Utilità dello screening ecografico delle cardiopatie congenite nelle gravide a basso rischio

La valutazione dell’integrità del cuore fetale è data dallo studio delle 4 camere durante l’ecografia morfologica del secondo trimestre, mentre nelle gravide cosiddette a rischio per cardiopatie congenite viene consigliato l’ecocardio fetale, dove oltre alle 4 camere vengono analizzate le altre strutture cardiache ed anche la loro funzionalità. La frequenza delle cardiopatie congenite, però, è del: 25-30% nelle gravide a rischio e del 70-75% nelle gravide a basso rischio. Nella nostra divisione di ostetricia abbiamo effettuato un test di screening su 1.030 gravide tra la 20ª e 24ª settimana considerate a basso rischio. Il test prevede lo studio delle 4-camere, dell’asse lungo sn, dell’asse lungo dx e dell’arco aortico. Le stesse scansioni vengono poi valutate con il color-Doppler. Il test è risultato positivo in 7 casi

Correlazione tra anomalie flussimetriche ed outcome in feti con IUGR

Il ritardo di crescita intrauterino (IUGR, Intrauterine Growth Restriction) (peso fetale <10° percentile) è una condizione patologica che complica la gravidanza in circa il 15% dei casi (1). La flussimetria Doppler dei vasi fetali e il profilo biofisico fetale rappresentano a tutt’oggi la metodica più efficace nonché l’unica disponibile per la sorveglianza del feto con IUGR (5). Abbiamo monitorizzato 33 gravide con IUGR comparso dopo la 27ª settimana; le pazienti sono state divise in 3 gruppi a seconda della settimana di comparsa del ritardo. Tutte le pazienti sono state sottoposte ad intervalli regolari a: valutazione biometrica, flussimetria arteriosa e venosa, calcolo AFI, CTG. L’outcome neonatale peggiore si è avuto nel 3° gruppo. Scopo del nostro studio è stato quello di verificare la correlazione tra anomalie della flussimetria fetale e outcome neonatale in feti con IUGR (CA < 10° percentile). Da quanto emerso dai risultati si può comprendere come l’epoca di comparsa del ritardo di crescita sia di grande rilevanza per la prognosi neonatale (8)

Speckle pattern interferometry : vibration measurement based on a novel CMOS camera

A digital speckle pattern interferometer based on a novel custom complementary metaloxide- semiconductor (CMOS) array detector is described. The temporal evolution of the dynamic deformation of a test object is measured using inter-frame phase stepping. The flexibility of the CMOS detector is used to identify regions of interest with full-field time averaged measurements and then to interrogate those regions with time-resolved measurements sampled at up to 7 kHz. The maximum surface velocity that can be measured and the number of measurement points are limited by the frame rate and the data transfer rate of the detector. The custom sensor used in this work is a modulated light camera (MLC), whose pixel design is still based on the standard four transistor active pixel sensor (APS), but each pixel has four large independently shuttered capacitors that drastically boost the well capacity from that of the diode alone. Each capacitor represents a channel which has its own shutter switch and can either be operated independently or in tandem with others. The particular APS of this camera enables a novel approach in how the data are acquired and then processed. In this Thesis we demonstrate how, at a given frame rate and at a given number of measurement points, the data transfer rate of our system is increased if compared to the data transfer rate of a system using a standard approach. Moreover, under some assumptions, the gain in system bandwidth doesn’t entail any reduction in the maximum surface velocity that can be reliably measured with inter-frame phase stepping

Evaluation of fatigue properties of 3D-printed Polyamide-12 by means of energy approach during tensile tests

Abstract Rapid prototyping and Additive Manufacturing are experiencing a continuous and rapid growth in different industrial fields, ranging from automotive to biomedical applications. They allow the creation of a wide range of devices in a short time with several materials, such as polymers and metals. On the other hand, the manufacturing process considerably affects the performance of the obtained 3D-printed materials and different laboratory tests are required in order to assess the mechanical properties, especially the fatigue behavior, of these materials. The present work is the result of the collaboration between the Engineering Department of the University of Messina and the rapid-prototyping company Skorpion Engineering. The aim of this work is to apply, for the first time on 3D-printed materials, the Static Thermographic Method for the fatigue assessment of Polyamide-12

Deep Learning algorithm for the assessment of the first damage initiation monitoring the energy release of materials

Monitoring the energy release during fatigue tests of common engineering materials has been shown to give relevant information on fatigue properties, reducing the testing time and material consumption.During a static tensile test, it is possible to assess two distinct phases: In the first phase (Phase I), where all the crystals are elastically stressed, the temperature trend follows the linear thermoelastic law; while, in the second phase (Phase II), some crystals begin to deform, and the temperature assumes a non-linear trend. The macroscopic transition stress between Phase I and Phase II could be related to the “limit stress” that, if cyclically applied, would lead to material failure. Nowadays, it is impossible to distinguish the transition between Phase I and Phase II in an objective way. Indeed, it is up to the operator's experiences.This work aims to create a universal methodology that predicts the limit stress by assessing the change in temperature trend by adopting Neural Networks. A Deep Learning algorithm has been created and trained on experimental data coming from static tensile tests performed on several classes of materials (steels, plastics, composite materials). Once trained, the network can predict the transition temperature at which the first plastic deformation occurs within the material

Energetic approach for the fatigue assessment of PE100

Abstract In the recent years, polyethylene, especially with its highest standard PE100, has been adopted in several industrial fields due to its good mechanical resistance and lightness, combined with low cost. On the other hand, the different manufacturing and working conditions severally affects its mechanical performances, hence extremely time-consuming fatigue tests have to be carried out in order to assess them. The Static Thermographic Method (STM) has been applied to a large set of engineering materials in order to evaluate the limit stress at which the material's surface temperature trend deviates from the linearity during a static traction test. In the present work, the STM is applied on PE100 in order to investigate its fatigue properties. The limit stress is compared with the fatigue limit obtained by traditional fatigue tests showing good agreement. The STM is a rapid tests procedure able to derive the fatigue properties of the material in a very short amount of time and with a limited number of specimens

Energy release as a parameter for fatigue design of additive manufactured metals

Additive manufacturing (AM) is spreading in a wide range of industrial fields. The influence of the printing parameters on the mechanical performance is still an open issue among researchers, particularly when dealing with fatigue loads, which can lead to an unexpected failure. Classical fatigue tests require a large amount of time and materials to be consumed. Compared to the traditional fatigue assessment, the thermographic method (TM) is able to derive in a very rapid way the SN curve and fatigue limit of the material monitoring its energetic release during fatigue tests. In this work, for the first time, the energetic release during fatigue test has been evaluated in specimens made of AISI 316L, obtained by SLM technique. Compared to literature data, the specimens show premature failure, even at low stress levels, with brittle fracture surfaces. The internal microstructure seems to be strictly related to the energetic release of the material

Energy release as a parameter for fatigue design of additive manufactured metals

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a new approach to the analysis of fatigue parameters by thermal variations during tensile tests on steel

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evaluation of mechanical properties of polyethylene for pipes by energy approach during tensile and fatigue tests

Abstract Since its introduction in pipe applications more than 40 years ago, polyethylene (PE) has been taking a growing place in gas and water distribution due to its low cost, lightness and good corrosion resistance. Besides, long-term properties have been steadily rising due to the development of novel PE-based materials. The present highest standard is the PE100 class. Several laboratory tests are used to extract design data for long-term failure-type prediction based on stress and time to failure relationship. It remains difficult to assess the relation between creep and fatigue loadings on the one side. On the other side, the manufacturing process of the test specimens influences considerably the obtained performance for viscoelastic materials subjected to working conditions. In present paper, the mechanical properties of high-density polyethylene (HDPE), PE 100 class, for pipes were investigated using experimental techniques. Thermographic technique was used during the static tests in order to identify the maximum stress zone and also during the fatigue tests to study the temperature evolution of the specimen. The aim of this study is the application of the Thermographic Method for the fatigue assessment of PE100