Alexandre da Silva Rocha

Antibody Anti-p16INK4a in Cervical Cytology

Objective To evaluate sensitivity, specificity and positive and negative predictive values (PPV, NPV) of anti-p16 INK4a in cervical cytology. Study Design A case-control study was conducted in a reference center for cervical pathology. Cytology slides were collected in a standard way with Ayre spatula and Cytobrush. The slides were interpreted by 2 independent pathologists (P1, P2). The cases (n = 61) represented all cervical examinations that had resulted in a biopsy with the diagnosis of CIN 1, 2 or 3 or squamous cell carcinoma. Controls (n = 87) included all examinations with negative cytology (Papanicolaou) and negative colposcopy. Results The sensitivity for the histologic diagnosis of CIN 2, 3 (n = 23) was 100% and 95.7% (P1, P2), respectively. The NPV for CIN 2 or worse was 100% (P1) and 98.9% (P2). The sensitivity for the diagnosis of CIN 1 was 77.8% (PI) and 58.3 % (P2). The NPV for CIN 1 or worse was 90.6% (PI) and 82 % (P2). The κ index between the 2 pathologists was 0.74. Conclusions Our results suggest that the antibody anti-p16 INK4a could contribute as an adjuvant tool in the follow-up of cervical intraepithelial lesions when the cytology sample is collected in the standard way.

Analysis by design of experiments of distortion potentials in drawn and induction hardened wire

In this investigation a DoE (Design of Experiments) analysis of distortion for a typical manufacturing process of pre-straightened, cold drawn and induction hardened AISI 1045 cylindrical steel bars was carried out. A careful characterization of the material, including residual stress states and geometrical changes, was done for the different manufacturing steps. In order to identify effects and correlations on distortion behavior, the investigated variables included the drawing process itself with two different drawing angles, a stress relief treatment, which was applied to one part of the samples, and, finally, induction hardening with two different case depths. Main and statistically significant effects on the distortion of the induction hardened samples were found to be in this order, the drawing angle, the stress relief treatment and the induction hardening depth. It was also found that the distortion potentials are transmitted from the drawing process to further manufacturing steps and, consequently, from one production site to the next.

Comparação entre difração de raios X e "método do furo cego" para medição de tensões residuais em barras cilíndricas

The residual stresses in the surface and subsurface of mechanical components during the manufacturing process can affect the behavior and represent a significant potential for deviations in shape and size. These residual stresses also represent one of the main potentials for the distortion (which are bending and dimensional changes) in mechanical components during the manufacture. Therefore, the determination of the distribution and the control of these residual stresses in each stage of the manufacturing process is of great importance. In this work, analysis of the variation of the residual stresses were accomplished in cold-drawed bars of AISI 1045 steel due to the manufacturing process. The bars were analyzed by X-ray diffraction (XRD) and hole-drilling (H.D) to characterize the residual stresses. Starting from the values of strains obtained, the longitudinal residual stresses were calculated for each tested point. With this work, a detailed view of the development of stress in the surface to a depth of 1mm of bars after the process steps was obtained.

Investigation of the Influence Factors on Distortion in Induction-Hardened Steel Shafts Manufactured from Cold-Drawn Rod

In this study, the distortion of steel shafts was investigated before and after induction hardening. Several essential influencing factors in the manufacturing process chain regarding cold drawing, cutting method, notches on the shafts, and induction hardening were analyzed by design of experiment (DoE). Further necessary examinations of microstructures, hardness profile, segregation of chemical composition, and residual stress state were conducted for understanding the distortion behavior. The results of the statistical analysis of the DoE showed that the drawing process is the most important factor influencing distortion. The surface hardening depth of induction hardening is the second main factor. The relationship between inhomogeneities in the work pieces and the distortion was finally discussed.

Distortion Analysis in the Manufacturing of Cold-Drawn and Induction-Hardened Components

In this investigation, a design of experiments analysis of distortion for a typical manufacturing process involving pre-straightening, cold drawing, and induction hardening of AISI 1045 cylindrical steel bars was carried out. A careful characterization of the material, including residual stress states and geometrical changes, was done for the different manufacturing steps. In order to identify effects and correlations on distortion behavior, the investigated variables included the batch influence, the combined drawing process itself with two different drawing angles and two different polishing and straightening (P.S.) angles, a stress relief treatment which was applied to a part of the samples, and finally induction hardening with two different surface hardening depths. Main and statistically significant effects on the distortion of the induction-hardened samples were found to be in this order: first, the interaction between the drawing angle and batch, then the interaction between drawing angles, and finally drawing angle and induction hardened layer. It was also found that the distortion potentials are transmitted from the drawing process to further manufacturing steps and, consequently, from one production site to the next.

Simulação computacional de um processo de trefilação para produção de barras redondas de aço AISI 1045

In this work, the wire-drawing production step for the production of AISI 1045 steel bars was numerically simulated. Different parameters necessary for the simulation were estimated based on current combined industrial drawing processes. Ring compression tests were carried out and simulated aiming at the determination of the friction value to be used in the simulation. From the numerical simulation results, the capacity of the simulation for estimating the drawing forces by comparison with analytical and empirical equations was evaluated. Besides this, an effort was made to simulate the residual stresses after drawing. The simulated residual stress profiles were then compared to experimental residual stresses profiles, which were obtained in a Neutron Diffraction experimental analysis carried out on industrial samples. Based on this work, the possibility of using simulation to quantitatively calculate residual stresses after the cold drawing was discussed. The carried out analysis will be used to implement improvements in the drawing process.

Residual stress analysis of drive shafts after induction hardening

Typically, for automotive shafts, shape distortion manifests itself in most cases after the induction hardening by an effect known as bending. The distortion results in a boost of costs, especially due to machining parts in the hardened state to fabricate its final tolerances. In the present study, residual stress measurements were carried out on automotive drive shafts made of DIN 38B3 steel. The samples were selected in consequence of their different distortion properties by an industrial manufacturing line. One tested shaft was straightened, because of the considerable dimensional variation and the other one not. Firstly, the residual stress measurements were carried out by using a portable difractometer, in order to avoid cutting the shafts and evaluate the original state of the stresses, and afterwards a more detailed analysis was realized by a conventional stationary diffractometer. The obtained results presented an overview of the surface residual stress profiles after induction hardening and displayed the influence of the straightening process on the redistribution of residual stresses. They also indicated that the effects of the straightening in the residual stresses cannot be neglected.

Comparison between Neutron Diffraction measurements and numerical simulation of residual stresses of a Wire-Drawing process

In this work, a drawing processed was simulated to calculate forces and the resulting residual stresses in the material. The calculated residual stresses were compared with experimentally measured residual stresses by the Neutron Diffraction Method. The modeled process was the Wire Drawing. The necessary parameters to model the process were taken from an industrial currently used process. Rods of an AISI 1045 steel with nominal diameters of 21.46 mm were reduced to 20.25 mm by drawing with an drawing angle of 15°. Compression tests were used to determinate flow curves of the real material an used in the simulation models. The possibility to estimate drawing forces by numerical simulation was evaluated by comparing simulated results with values from empirical equations given by the literature. The results have shown a sufficient accuracy for the calculation of forces, but the comparison of residual stresses has shown differences to the experimentally determined ones that can be minimized by the consideration of high strain rates in the compression tests, anisotropy of the material and kinematic hardening.

Assessment of the Fournier® Cervical Specimen Self-Sampling Device Using the Papanicolaou Method

Introduction: Communities of socially excluded immigrant women, especially Muslim, Asian, Aboriginal and Maroon, are among the groups of women with low rates of cervical screening. Exclusion of the pelvic examination could result in a higher acceptance of the cervical screening among these communities and an increase in screening coverage. Aim: To assess the performance of the Fournier® cervical specimen self-sampling device for the cytological diagnosis of precursor or neoplastic lesions in the uterine cervix using the Papanicolaou method. Methods: A case-control study was conducted at the Cervical Pathology Outpatient Clinic. Liquid-based cytology slides were obtained by the Fournier device and stained using the Papanicolaou method. The slides were analyzed by two pathologists, blinded for the colposcopic and histological results and compared to Papanicolaou smears that were obtained using the traditional method of speculum examination. Results: There were 68 patients who were considered free from precursor or neoplastic cervical lesions. There were 35 cases of low-grade lesions, 13 cases of high-grade lesions and 3 cases of squamous-cell carcinoma. According to the first and second pathologists, the sensitivities of the device for identifying precursor or neoplastic cervical lesions were 50.0 and 60.0%, and the specificities of the method were 81.8 and 73.8%. According to the first and second pathologists, the positive predictive values of the diagnostic test were 0.67 and 0.63, and the negative predictive values were 0.68 and 0.71, respectively. Conclusion: Sensitivity and specificity of the Fournier device test was comparable to Papanicolaou smears tests obtained using the traditional method with speculum examination.

ESTUDO DO COMPORTAMENTO DO ALUMÍNIO (Al) COM ADIÇÃO DE 1% COBRE (Cu) OBTIDO PELA METALURGIA DO PÓ CONVENCIONAL

Powder metallurgy is a mechanical forming process with increasing applicability in the Brazilian industrial scenario. Application fields include, for example, manufacturing of automotive components, home appliances, cutting tools and electric tools. Sintering is the most important phase of the process, in which the already compacted powder is subjected to a temperature below its melting point, obtaining a material with excellent finish, dimensional accuracy and mechanical properties. The present work aims to assess the behavior of aluminum with the addition of 1% Copper, specifically evaluating density, hardness and metallography presented as a function of applied loads on each of the samples was between 100 MPa to 1,000 MPa. The metallography presented porosity inherent in the process, but there was a hardness increase from 40 to 50 HV. Keywords: Powder metallurgy, Aluminum Copper composition, hardness, density and metallography.