Modification, Ablation and Hardening of Metallic Surfaces by a Cryogenic Nitrogen Jet

AbstractThis contribution gives the first results of an ongoing research aiming at developing a new surface treatment technique usinga supercritical nitrogen jet, named Jazolthop, for surface modification. As nitrogen is naturally recycled within air, this new process has a high potential for surface treatment without any chemical, physical or sewage effluents. This contribution shows that, pending on the operating condition, the technique can be used (i) under a stripping or ablation mode as well as, in a “less conventional” approach, (ii) for surface hardening.Illustration of the ablation mode is given for a Ti-6Al-4V alloy treated under static conditions using an intrusive jet. After 2min of treatment, a thickness of 200μm was removed from the surface by successive stripping out of micro-chips.Illustration of the hardening mode is given through the analysis of stainless steels treated under the cryogenic jet at a moving torch velocity of 5mm/min. The jet conditions were selected to be less intrusive and trigger the martensitic transformation without creating surface flaws of micro-cavities. In this case, the hardness of the steels was more than doubled after the passage of the cryogenic jet

Early Detection of Prostate Cancer: The Role of Scent

Prostate cancer (PCa) represents the cause of the second highest number of cancer-related deaths worldwide, and its clinical presentation can range from slow-growing to rapidly spreading metastatic disease. As the characteristics of most cases of PCa remains incompletely understood, it is crucial to identify new biomarkers that can aid in early detection. Despite the prostate-specific antigen serum (PSA) levels, prostate biopsy, and imaging representing the actual gold-standard for diagnosing PCa, analyzing volatile organic compounds (VOCs) has emerged as a promising new frontier. We and other authors have reported that highly trained dogs can recognize specific VOCs associated with PCa with high accuracy. However, using dogs in clinical practice has several limitations. To exploit the potential of VOCs, an electronic nose (eNose) that mimics the dog olfactory system and can potentially be used in clinical practice was designed. To explore the eNose as an alternative to dogs in diagnosing PCa, we conducted a systematic literature review and meta-analysis of available studies. PRISMA guidelines were used for the identification, screening, eligibility, and selection process. We included six studies that employed trained dogs and found that the pooled diagnostic sensitivity was 0.87 (95% CI 0.86–0.89; I2, 98.6%), the diagnostic specificity was 0.83 (95% CI 0.80–0.85; I2, 98.1%), and the area under the summary receiver operating characteristic curve (sROC) was 0.64 (standard error, 0.25). We also analyzed five studies that used an eNose to diagnose PCa and found that the pooled diagnostic sensitivity was 0.84 (95% CI, 0.80–0.88; I2, 57.1%), the diagnostic specificity was 0.88 (95% CI, 0.84–0.91; I2, 66%), and the area under the sROC was 0.93 (standard error, 0.03). These pooled results suggest that while highly trained dogs have the potentiality to diagnose PCa, the ability is primarily related to olfactory physiology and training methodology. The adoption of advanced analytical techniques, such as eNose, poses a significant challenge in the field of clinical practice due to their growing effectiveness. Nevertheless, the presence of limitations and the requirement for meticulous study design continue to present challenges when employing eNoses for the diagnosis of PCa

Analysis of Fingerprint Pores for Vitality Detection

Spoofing is an open-issue for fingerprint recognition systems. It consists in submitting an artificial fingerprint replica from a genuine user. Current sensors provide an image which is then processed as a “true” fingerprint. Recently, the so-called 3rd-level features, namely, pores, which are visible in high-definition fingerprint images, have been used for matching. In this paper, we propose to analyse pores location for characterizing the “liveness” of fingerprints. Experimental results on a large dataset of spoofed and live fingerprints show the benefits of the proposed approach

Surface oxidation and phase transformation of the stainless steel by hybrid laser-waterjet impact

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Analyse par diffraction des rayons X d'une couche de laiton obtenue par dépôt d'une couche de cuivre, d'une couche de zinc et diffusion

Les dépôts d'alliages binaires (laiton, bronze, ...) sont fréquemment obtenus par électrodéposition à partir de bains cyanurés. Cette technique permet de grandes vitesses de dépôt, mais les risques liés à l'utilisation de ces bains obligent les industriels à rechercher de nouvelles solutions. Une technique de substitution consiste à déposer une bicouche formée des deux métaux constituant l'alliage (dépôt séquentiel des deux métaux), puis à obtenir l'alliage par diffusion. Pour contrôler ce procédé, plusieurs points importants sont à vérifier après diffusion : les phases présentes dans la couche et leur quantité, ainsi que l'homogénéité de composition de ces phases. Cette étude présente les travaux réalisés pour analyser ces paramètres par diffraction des rayons X. L'analyse d'une couche de laiton obtenue par dépôt séquentiel de cuivre, de zinc et diffusion est présentée.Layers of binary alloys (brass, bronze, ...) are usually electroplated from cyanides baths. This technique allows high rates of deposition and works safely, but there are some risks in using cyanides. Therefore new ways of electro-deposition are investigated. One manufacturing process consists of successively depositing the two metals and of obtaining inter-metallic diffusion by heating the bilayer. Usually, it is essential to know the exact phases and their proportions, in order to control the deposition and diffusion processes. In this study, are presented X ray diffraction methods to control the layer. As an exarnple, analysis of a brass layer obtained by sequential plating plus diffusion process is given

Study of CuAlBe Shape Memory Alloy by X-Ray Diffraction

A complete study of Ms-30°C polycrystalline CuAlBe shape memory alloy is made by X Ray diffraction using a texture goniometer equipped with a curved position sensitive detector. Austenite and martensite unit cells parameters are measured. Measured indexes and orientation of the habit plane are compared to those expected by the lattice parameters. Austenite after extrusion shows a strong fiber texture, volumic fraction of austenite and martensite are rneasured according to the deformation. Internal deformations of three grains of a Ms-100°C CuAlBe sample are followed during their macroscopic deformation