Navegando por Assunto "Raman spectroscopy"

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    Finding reduced Raman spectroscopy fingerprint of skin samples for melanoma diagnosis through machine learning
    (Elsevier) Araújo, Daniella Castro; Veloso, Adriano Alonso; Oliveira Filho, Renato Santos de; Giraud, Marie-Noelle; Raniero, Leandro José; Ferreira, Lydia Masako; Bitar, Renata Andrade
    Early-stage detection of cutaneous melanoma can vastly increase the chances of cure. Excision biopsy followed by histological examination is considered the gold standard for diagnosing the disease, but requires long high- cost processing time, and may be biased, as it involves qualitative assessment by a professional. In this paper, we present a new machine learning approach using raw data for skin Raman spectra as input. The approach is highly efficient for classifying benign versus malignant skin lesions (AUC 0.98, 95% CI 0.97–0.99). Furthermore, we present a high-performance model (AUC 0.97, 95% CI 0.95–0.98) using a miniaturized spectral range (896–1039 cm− 1), thus demonstrating that only a single fragment of the biological fingerprint Raman region is needed for producing an accurate diagnosis. These findings could favor the future development of a cheaper and dedicated Raman spectrometer for fast and accurate cancer diagnosis.
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    Integrating Raman spectroscopy and RT-qPCR for enhanced diagnosis of thyroid lesions: a comparative study of biochemical and molecular markers
    (Elsevier) Medeiros Neto, Lázaro Pinto; Santos, Laurita dos; Carvalho, Luís Felipe C. S.; Santos, André Bandiera de Oliveira; Martin, Aírton Abrahão; Canevari, Renata de Azevedo
    Thyroid cancer is the most prevalent endocrine malignancy, with increasing incidence due to advancements in diagnostic techniques. Ultrasound (US) and fine needle aspiration (FNA) cytology, widely used in clinical practice, have detection accuracies ranging from 65 % to 95 %. However, these methods may yield inconclusive or difficult-to-interpret results, emphasizing the need for complementary diagnostic techniques. This study ex- plores the integration of Raman spectroscopy and gene expression analysis via RT-qPCR to improve the diagnosis of thyroid lesions, classified into groups: follicular thyroid carcinoma (FTC), papillary thyroid carcinoma (PTC) and goiter tissues. Healthy tissue samples were used as normalizing controls in both analysis. Raman spectros- copy analyzed 35 samples, while RT-qPCR assessed 33 samples. For comparison, the same 19 samples previously analyzed by both techniques were examined. Raman spectroscopy, a non-invasive technique, has shown effec- tiveness in distinguishing between benign and malignant thyroid tissues by identifying key biochemical com- ponents such as DNA, RNA, proteins, and lipids. The distinguishing of FTC from goiter using Raman spectroscopy achieved an accuracy rate of 82.3 %. Gene expression analysis via RT-qPCR focused on six genes: TG, TPO, PDGFB, SERPINA1, TFF3, and LGALS3. Specifically, SERPINA1 was overexpressed in PTC, TFF3 showed elevated levels in FTC, and LGALS3 was elevated in both PTC and FTC compared to goiter and normal tissues. These findings align with existing literature, suggesting that these genes could serve as valuable diagnostic molecular markers. The expression analysis of these genes within this subset of samples demonstrated concordance with the classification derived from PCA of Raman spectroscopy data. The integration of Raman spectroscopy and RT- qPCR offers a complementary approach to traditional histological analysis, providing enhanced sensitivity and specificity in diagnosing thyroid lesions.
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    Tribocorrosion studies on DLC films with silver nanoparticles for prosthesis applications
    (IOP Publishing) Radi, Polyana Alves; Vieira, Lúcia; Leite, Priscila Maria Sarmeiro Corrêa Marciano; Trava-Airoldi, Vladimir Jesus; Massi, Marcos; Reis, Danieli Aparecida Pereira
    Metals and their alloys are very important for orthopedic applications, and the basic requirements for a successful implant are chemical stability, mechanical behavior, and biocompatibility in body fluids and tissues. For prosthesis applications, the corrosion resistance of metals is one of the major prerequisites to avoid impairment of the material properties due to degradation. The combined action of corrosion and wear on the material is called tribocorrosion and DLC (Diamond-Like Carbon) films have been extensively studied to increase prosthesis biocompatibility and to protect from corrosion. Additionally, DLC coatings can prevent the prosthesis to release toxic elements due to plastic deformation and corrosion. This paper is about tribocorrosion studies on DLC and DLC-Ag (DLC containing silver nanoparticles) on Ti-6Al-4V substrates. These films were obtained by PECVD (Plasma Enhanced Chemical Vapor Deposition) using hexane as a precursor. The tribocorrosion behavior of uncoated and coated samples was investigated in the reciprocating mode in Ringer's lactate solution. From the polarization test results, the protective efficiency of the film was calculated. Silver nanoparticles improved the corrosion resistance of the films. The protective efficiency was 15 and 19% for DLC and DLC-Ag films, respectively.