Feasibility of Local Stress Relaxation by Laser Annealing and X‐ray Measurement

Most manufacturing processes generate residual stresses inside the materials and components. Stress relief heat treatments can be used to reduce the magnitude of the residual stresses: by uniformly heating a structure to a sufficiently high temperature, and then uniformly cooling it, residual stresses can be relaxed. This process generally requires the insertion of the entire component in a large furnace, for a fairly long period of time. In this paper, the possibility of using a high power laser source to locally relieve residual stresses is studied; this has the advantage of calibrating and confining the relief process just to the laser affected area. An experimental set‐up was tested on an aluminium specimen, and the preliminary results are reported in this paper.     

Strain Field Analysis in Electronic Components by ESPI: Bad Thermal Contact and Damage Evaluation

Designing electronic components and devices is a complex task that must include also considerations about thermo-mechanical behavior of the component itself. This aspect, in fact, can affect the reliability of the device as a consequence of the thermal stresses that are introduced in the component while it is working. Stress concentration can arise, in fact, due to different thermal expansion coefficients of the materials involved. Determining the thermo-mechanical response by numerically methods is not simple and not always possible so that experimental methods are preferable. In this paper, specifically, the electronic speckle pattern interferometry technique was adopted to measure full-field strain of the component during exercise. By using an optical technique it is possible to get information about the behavior of the component without being in contact with the component itself so that the dissipation coefficient is not altered. The system was able to detect gradients of deformation in the component itself connected to the different distribution of internal current in the component. Moreover, it was observed, that the presence of bad thermal contact between the package and the heat sink can be revealed because it results in a different thermos-mechanical behavior of the component. Finally, a critical defect was introduced in the component and it was observed the way the presence of damage affects the in-plane displacement of the component. Very huge differences were observed leading to the consideration that this kind of approach could be conveniently adopted also as a damage detection tool.     

Experimental Analysis of Thermo‐mechanical Behaviour of Electronic Components with Speckle Interferometry

Experimental investigations of thermo‐mechanical behaviour of electronic components may help to prevent catastrophic in‐service failures. Non‐contact optical techniques such as speckle and moiré interferometry are naturally suited for carrying out measurements on electronic equipment as they are non‐invasive techniques and provide high‐resolution full‐field information on displacements. In spite of its inherent ability to measure deformations at the nanometer level, there are few examples of application of speckle interferometry to true monitoring of thermo‐mechanical behaviour of electronic components in real time. For this reason, the paper presents a phase shifting electronic speckle pattern interferometry (PSESPI) experimental set‐up developed in order to monitor the time evolution of thermal deformations in electronic components for aerospace applications submitted to normal or anomalous working conditions. Cyclic loads are also analysed to assess fatigue behaviour. Experimental results obtained for whole electronic boards and single components mounted on board fully demonstrate the capability of PSESPI to detect even small differences in thermo‐mechanical response between normal and anomalous functioning.     

Residual stress measurement on Titanium Grade 5 and Inconel 625 thin dissimilar welded joints by contour method

Journal of Materials Science - Residual stress assessment is a key factor in engineering design owing to its impact on engineering properties of materials, structural components and welded joints....     

White cell-reduced red cells prepared by filtration: a critical evaluation of current filters and methods for counting residual white cells

Atrial natriuretic peptide (ANP) is reported to dilate a major coronary artery in both experimental animals and humans. Spasm of a major coronary artery is the cause of variant angina pectoris and can be induced by hyperventilation. The effect of the ANP infusion on anginal attack induced by hyperventilation was studied in patients with variant angina pectoris. The study was performed in the early morning on 3 consecutive days in 11 patients with variant angina pectoris in whom the attacks were reproducibly induced by hyperventilation. On days 1 and 3 (saline solution infusion), and day 2 (ANP infusion), hyperventilation was started 14 minutes after beginning infusion of ANP (0.1 microgram/kg/min) or saline solution for 6 minutes. The attacks were induced in all 11 patients by hyperventilation on days 1 and 3. However, the attacks were not induced in any patient on day 2 of the ANP infusion. The plasma ANP level increased from 33 +/- 7 pg/ml to the peak level of 2,973 +/- 479 pg/ml (p < 0.01) at the end of the ANP infusion, and the plasma level of cyclic guanosine monophosphate (cGMP) increased from 5 +/- 1 pmol/ml to the peak level of 58 +/- 6 pmol/ml (p < 0.01) 5 minutes after the ANP infusion. The plasma levels of ANP and cGMP did not change after hyperventilation on days 1 and 3. It is concluded that the ANP infusion suppresses the attacks induced by hyperventilation in patients with variant angina pectoris, and cGMP is related to the mechanisms of suppression of the attacks.     

Relationship of the time of storage and transfusion reactions to platelet concentrates from buffy coats

BACKGROUND: Transfusion reactions to platelet concentrates prepared from buffy coats (BC-PCs) were reviewed to determine the effect of some variables of BC-PC preparation and storage: time of BC storage before BC-PC preparation (1-2 days); time of BC-PC storage before transfusion (1-5 days); no white cell reduction versus laboratory and bedside BC-PC white cell reduction. STUDY DESIGN AND METHODS: A multiple linear logistic regression model was used by which the relative effect of one variable is expressed as the relative risk of transfusion reaction against a baseline level (1-day storage, no white cell reduction). RESULTS: During the 14 months of study, a total of 2707 BC-PC transfusions were given to 192 patients; 37 reactions (1.4%) were reported in 25 patients (13%). The transfusion reactions were febrile, nonhemolytic in 23 cases; allergic in 5; febrile and allergic in 2; and other in 7. The relative risk of transfusion reaction to BC-PCs prepared from BCs stored for 2 days was 1.98 times that to BC-PCs prepared from BCs stored for 1 day (p = 0.07). The relative risk of transfusion reaction of 5-day-old BC-PCs was 10.7 times that of 1-day-old BC-PCs (p = 0.001). The relative risk of transfusion reactions of BC-PCs white cell-reduced in the laboratory and at the bedside were 0.65 (p = 0.3) and 1.87 (p = 0.1) times, respectively, that of non-white cell-reduced BC-PCs. CONCLUSION: Time of storage seems to be an important variable associated with BC-PC transfusion reaction.     

Thyroid vascularization by color doppler ultrasonography in Graves' disease. Changes related to different phases and to the long-term outcome of the disease

To investigate possible correlations between thyroid vascularization and activity of Graves' disease, we measured blood flow (TBF) at the inferior thyroid artery and intraparenchymal vascularization (number of vessels per square centimeter) by color Doppler ultrasonography (CDU) on Graves' patients at different phases of the disease. We studied 88 patients cross sectionally: 22 untreated; 17 euthyroid after 6 months of methimazole; 49 euthyroid at drug withdrawal after 12 to 24 months of treatment. The patients of the latter group were followed up for 29.1 +/- 6.3 months after discontinuation of treatment. On the day of CDU examination, free triiodothyronine (FT3), free thyroxine (FT4), thyrotropin (TSH), antiperoxidase and anti-TSH receptor (TRAb) antibodies were measured. Vascularization indices were significantly higher in the Graves' patients than in controls. In the patients euthyroid under treatment, vascularization was not significantly lower than in the untreated group, but TBF and vessel number both appeared clearly reduced in the patients tested at drug withdrawal. The vascularization indices at drug withdrawal were significantly higher in the patients who relapsed than in those in stable remission: TBF (mL/min) 50.6 +/- 36.8 vs. 23.8 +/- 17.5, p = 0.001; vessel number/cm2 1.8 +/- 0.8 vs. 0.8 +/- 0.5, p = 0.002. A multivariate analysis, evaluating the predictive value of vascularization, hormonal and immunological parameters for relapse, demonstrated a significant predictive value for TRAb (RR 8.2; p = 0.001) and a weak predictive value for TBF (RR 1.1; p = 0.02). In conclusion, CDU examination confirms that thyroid hypervascularization in Graves' disease is not related to thyroid hormone circulating levels. The association of increased TBF and high levels of TRAb in the relapsing forms of disease suggests that thyroid hypervascularization is probably related to the activity of the underlying autoimmune processes.