Artificial Neural Networks and Experimental Analysis of the Resistance Spot Welding Parameters Effect on the Welded Joint Quality of AISI 304.

The automobile industry relies primarily on spot welding operations, particularly resistance spot welding (RSW). The performance and durability of the resistance spot-welded joints are significantly impacted by the welding quality outputs, such as the shear force, nugget diameter, failure mode, and the hardness of the welded joints. In light of this, the present study sought to determine how the aforementioned welding quality outputs of 0.5 and 1 mm thick austenitic stainless steel AISI 304 were affected by RSW parameters, such as welding current, welding time, pressure, holding time, squeezing time, and pulse welding. In order to guarantee precise evaluation and experimental analysis, it is essential that they are supported by a numerical model using an intelligent model. The primary objective of this research is to develop and enhance an intelligent model employing artificial neural network (ANN) models. This model aims to provide deeper knowledge of how the RSW parameters affect the quality of optimum joint behavior. The proposed neural network (NN) models were executed using different ANN structures with various training and transfer functions based on the feedforward backpropagation approach to find the optimal model. The performance of the ANN models was evaluated in accordance with validation metrics, like the mean squared error (MSE) and correlation coefficient (R2). Assessing the experimental findings revealed the maximum shear force and nugget diameter emerged to be 8.6 kN and 5.4 mm for the case of 1-1 mm, 3.298 kN and 4.1 mm for the case of 0.5-0.5 mm, and 4.031 kN and 4.9 mm for the case of 0.5-1 mm. Based on the results of the Pareto charts generated by the Minitab program, the most important parameter for the 1-1 mm case was the welding current; for the 0.5-0.5 mm case, it was pulse welding; and for the 0.5-1 mm case, it was holding time. When looking at the hardness results, it is clear that the nugget zone is much higher than the heat-affected zone (HZ) and base metal (BM) in all three cases. The ANN models showed that the one-output shear force model gave the best prediction, relating to the highest R and the lowest MSE compared to the one-output nugget diameter model and two-output structure. However, the Levenberg-Marquardt backpropagation (Trainlm) training function with the log sigmoid transfer function recorded the best prediction results of both ANN structures.

Tomographic and Tension Analysis of Polypropylene Reinforced with Carbon Fiber Fabric by Injection Molding.

The use of thermoplastic materials has had significant growth in recent years. However, with great mechanical requirements, thermoplastics have limitations to their use. To improve these restrictions, these materials are reinforced to obtain better properties. Polypropylene is one of the most versatile polymers and is used in almost all modern industries. Thus, the aim of this study is to create composite materials that offer performance for various industrial fields using carbon fiber fabric reinforcement, which is an inexpensive material widely used by the aerospace, automotive, and marine industries. The samples are produced by the over-injection molding of polypropylene. The investigation is focused on the impact of two critical control parameters in the injection molding process: temperature and pressure. Twelve experiments have therefore been considered, taking into account the combination of three factors: the presence or absence of carbon fiber fabric reinforcement, three levels of temperature (200 °C, 220 °C, and 240 °C), and two injection pressures (5000 kPa and 10,000 kPa). To evaluate the influence of these factors, three analyses were carried out: first, on the samples' shrinkage using a portable metrology-grade 3D laser scanner; second, on the internal defects using computed tomography (CT); and third, on the mechanical properties with tensile tests. From the results obtained, it is observed that the mold shrinkage fell slightly when PP samples were reinforced with carbon fiber, with both materials (PP and carbon-fiber-reinforced PP) having linear behavior with temperature. It is also noticed that polypropylene behaves as a crystalline material when processed at higher temperatures and pressures. From tests on the mechanical properties, it is concluded that the mean yield strength of PP-CF for injection temperatures of 220 °C and 240 °C represents an increase of 43% compared to the non-reinforced material.

Myxoid Pseudotumor Changes Affecting the Distal Ureter Associated With Urothelial Carcinoma In Situ.

Myxoid pseudotumor is a pseudoneoplastic fibroblastic proliferation that has been described in the perinephric and renal sinus fat tissue. It is characterized by the presence of a myxoid matrix, intermingled with the adipocytes, and a hypocellular population of spindle-shaped and stellate cells. We report a myxoid pseudotumor involving the distal ureter, which broadens the spectrum of possible localizations of this lesion around the urinary tract. It occurred in an 80-year-old patient who underwent a nephroureterectomy indicated after an incidental radiological finding of a thickening of the distal left ureter wall which suggested a ureteral neoplasm. He had two voided urine and one ureteroscopic sample cytologies diagnosed as high-grade urothelial carcinoma, as well as a retrograde ureteroscopy ureteral biopsy which was diagnosed as urothelial carcinoma in situ. This emphasizes the problem of the possible misdiagnosis of myxoid pseudotumor as a ureteral infiltrative carcinoma due to the radiological findings being badly interpreted, compounded by the preoperative cytohistologic data on malignancy. A diffuse urothelial carcinoma in situ was seen in our specimen without infiltrative or papillary tumors. This would not support an obstructive pathogenetic mechanism as has been hypothesized for myxoid pseudotumor.

Tunable Magnetic Properties of Interconnected Permalloy Nanowire Networks.

In this study, we investigate the magnetic properties of interconnected permalloy nanowire networks using micromagnetic simulations. The effects of interconnectivity on the hysteresis curves, coercivity, and remanence of the nanowire networks are analyzed. Our results reveal intriguing characteristics of the hysteresis curves, including nonmonotonic behaviors of coercivity as a function of the position of horizontal nanowires relative to vertical nanowires. By introducing horizontal nanowires at specific positions, the coercivity of the nanowire networks can be enhanced without altering the material composition. The normalized remanence remains relatively constant regardless of the position of the horizontal wires, although it is lower in the interconnected nanowire arrays compared to nonconnected arrays. These findings provide valuable insights into the design and optimization of nanowire networks for applications requiring tailored magnetic properties.

Dynamic susceptibility of Fe3O4 nanotubes.

In this work we performed a detailed numerical analysis to investigate the dynamic susceptibility of 1000 nm long Fe3O4 nanotubes by varying the diameter, the tube wall thickness and the magnitude of the external magnetic field applied along the tube axis. We found two well-defined modes, one of low frequency associated with the caps of the nanotubes, and another of high frequency associated with the central area of the nanotubes, which can be controlled by varying the geometry of the tubes or the external magnetic field to which they are subjected. These results allow us to suggest the use of these nanotubes in applications that require controlling the resonant frequency in the GHz range.

Renal Angiomyolipoma: A Diagnostic and Therapeutic Challenge.

BACKGROUND: Angiomyolipomas (AML) represent less than 10% of renal tumours. They are most often detected incidentally during imaging tests, but there are several histological variants that pose difficulties in the radiological differential diagnosis. Their identification should allow the loss of renal parenchyma due to embolization or radical surgery to be prevented. METHODS: Retrospective study of patients undergoing kidney surgery with post-surgical pathological diagnosis of AML at the Álvaro Cunqueiro Hospital (2016-2021). Patients with a radiological diagnosis of AML who underwent surgery based on clinical criteria were excluded. RESULTS: 18 patients were registered, allowing for the assessment of 18 renal tumours. All of the cases were diagnosed incidentally. Preoperative radiological diagnosis was: 9 lesions suggestive of renal cell carcinoma (RCC) (50%), 7 cases suggestive of RCC vs. AML (38.9%) and 2 lesions suggestive of AML vs. retroperitoneal liposarcoma (11.1%). Histological variants of AML were found in 61.1% of cases (n = 11). The most widely used surgical technique was partial nephrectomy, in 66.67% of cases. CONCLUSIONS: The radiological differential diagnosis of AML, and particularly its variants, with malignant lesions have important limitations either due to the predominance or scarcity of any of the AML components. Some cases can also pose difficulties at the histological level. This fact highlights the importance of the specialization of uroradiologists and uropathologists and the performance of kidney-sparing therapeutic techniques.

Characterization of 5356 Aluminum Walls Produced by Wire Arc Additive Manufacturing (WAAM).

Wire arc additive manufacturing (WAAM) is renowned for its high deposition rate, enabling the production of large parts. However, the process has challenges such as porosity formation, residual stresses, and cracking when manufacturing aluminum parts. This study focuses on ana-lyzing the porosity of AA5356 walls manufactured using the WAAM process with the Fronius cold metal transfer system (Wels, Austria). The walls were machined to obtain specimens for tensile testing. The study used computed tomography and the tensile test to analyze the specimens' porosity and its potential relation to tensile strength. The process parameters analyzed were travel speed, cooling time, and path strategy. In conclusion, increasing travel speed and cooling time significantly affects pore diameter due to the lower heat input to the weld zone. Porosity can be reduced when diminishing heat accumulation. The results indicate that an increase in travel speed produces a slight decrease in porosity. Specifically, the total pore volume diminishes from 0.42 to 0.36 mm3 when increasing the travel speed from 700 to 950 mm/min. The ultimate tensile strength and maximum elongation of the 'back and forth' strategy are slightly higher than those of the 'go' strategy. After tensile testing, the ultimate tensile strength and yield strength did not show any relation to the porosity measured by computed tomography. The percentage of the pore total volume over the measured volume was lower than 0.12% for all the scanned specimens.

Static and Dynamic Magnetic Properties of Fe3O4 Nanotubes.

In this paper, our objective was to investigate the static and dynamic magnetic properties of Fe3O4 nanotubes that are 1000 nm long, by varying the external radius and the thickness of the tube wall. We performed a detailed numerical analysis by simulating hysteresis curves with an external magnetic field applied parallel to the axis of the tubes (along the z-axis). Our findings indicate that nanotubes with an external radius of 30 nm exhibit non-monotonic behavior in their coercivity due to a change in the magnetization reversal mechanism, which was not observed in nanotubes with external radii of 80 nm. Additionally, we explored the dynamic susceptibility of these nanotubes and found that the position and number of resonance peaks can be controlled by manipulating the nanotube geometry. Overall, our study provides valuable insights into the behavior of Fe3O4 nanotubes, which can aid in the design and improvement in pseudo-one-dimensional technological devices.

Renal Angiomyolipoma: A Diagnostic and Therapeutic Challenge

Background: Angiomyolipomas (AML) represent less than 10% of renal tumours. They are most often detected incidentally during imaging tests, but there are several histological variants that pose difficulties in the radiological differential diagnosis. Their identification should allow the loss of renal parenchyma due to embolization or radical surgery to be prevented. Methods: Retrospective study of patients undergoing kidney surgery with post-surgical pathological diagnosis of AML at the Álvaro Cunqueiro Hospital (2016–2021). Patients with a radiological diagnosis of AML who underwent surgery based on clinical criteria were excluded. Results: 18 patients were registered, allowing for the assessment of 18 renal tumours. All of the cases were diagnosed incidentally. Preoperative radiological diagnosis was: 9 lesions suggestive of renal cell carcinoma (RCC) (50%), 7 cases suggestive of RCC vs. AML (38.9%) and 2 lesions suggestive of AML vs. retroperitoneal liposarcoma (11.1%). Histological variants of AML were found in 61.1% of cases (n = 11). The most widely used surgical technique was partial nephrectomy, in 66.67% of cases. Conclusions: The radiological differential diagnosis of AML, and particularly its variants, with malignant lesions have important limitations either due to the predominance or scarcity of any of the AML components. Some cases can also pose difficulties at the histological level. This fact highlights the importance of the specialization of uroradiologists and uropathologists and the performance of kidney-sparing therapeutic techniques (AU)

SATB2 as a Marker of the Proximal Nephron: Expression in Nephrogenic Adenoma and Correlation With Other Renal Tubular Markers.

Nephrogenic adenoma (NA) is an infrequent reactive urothelial lesion. The expression of immunohistochemical renal tubular markers has been reported in NA, although a proximal or distal nephron phenotype has not been established. Special AT-rich sequence-binding protein 2 (SATB2) is a marker of a colorectal origin of adenocarcinomas, occasionally reported in renal samples. We have analyzed SATB2 expression in NA, with correlation with other tubular markers, as well as in the normal kidney. Fifty cases of NA were immunostained with PAX8, SATB2, proximal nephron markers [CD10, renal cell carcinoma (RCC) marker, alpha-methylacyl-CoA racemase (AMACR), and CD15], and distal markers (Ksp cadherin, cytokeratin 7, E-cadherin (E-cad), and cytokeratin 19). Ten normal kidney sections were stained with a double method combining SATB2 plus CD10, RCC marker, AMACR, Ksp cadherin, cytokeratin 7, or E-cad. All NA were immunoreactive for PAX8 and 57% for SATB2. Every case was positive for proximal and distal nephron markers: 100% for cytokeratins 7 and 19, 84.1% E-cad +, 81.6% AMACR +, 68.9% Ksp cadherin +, 63% CD15 +, 53.3% CD10 +, and 28.6 % RCC +. In the normal kidney, SATB2 was detected in the straight part of the proximal tubules and the thin descending loops of Henle. NA shows a multiphenotypic pattern with coexpression of both proximal and distal nephron markers, and constant expression of PAX8, cytokeratins 7 and 19. SATB2 is often positive in NA, which should be kept in mind to avoid a possible misdiagnosis of intestinal adenocarcinoma. SATB2 is a marker of the normal proximal nephron.

Intraductal Carcinoma of the Prostate without High-Grade Invasive Adenocarcinoma: Report of Two Cases and Review of the Literature.

OBJECTIVES: Intraductal carcinoma of the prostate (IDC-P) is usually associated with high grade, aggresive acinar adenocarcinomas. IDC-P is supposed to result from the spread of the adenocarcinoma along the prostatic ducts. IDC-P rarely occurs without invasive carcinoma or with a coexistent low grade adenocarcinoma. MATERIAL AND METHODS: We report two patients, 66 and 75 year-old, who presented IDC-P and low-grade acinar adenocarcinoma foci in their radical prostatectomy surgical specimens. RESULTS: Acinar adenocarcinomas were grade group 1, PTEN+, pT2. In the first case, the invasive adenocarcinoma was adjacent but nor intermingled with the IDC-P, and a discordance in the immunophenotype between them was outstanding (positivity for ERG in the acinar carcinoma being negative in the IDC-P). In the second case, the foci of adenocarcinoma were distant from the IDC-P. The first patient had not biochemical recurrence after a 34 month follow-up period. CONCLUSIONS: This kind of cases supports the existence of an infrequent subtype of IDC-P that could be considered as an in situ neoplasia.

Intraductal Carcinoma of the Prostate without High-Grade Invasive Adenocarcinoma: Report of Two Cases and Review of the Literature

Objectives: Intraductal carcinoma of the prostate (IDC-P) is usually associated with high grade, aggresive acinar adenocarcinomas. IDC-P is supposed to result from the spread of the adenocarcinoma along the prostatic ducts. IDC-P rarely occurs without invasive carcinoma or with a coexistent low grade adenocarcinoma. Material and Methods: We report two patients, 66 and 75 year-old, who presented IDC-P and low-grade acinar adenocarcinoma foci in their radical prostatectomy surgical specimens. Results: Acinar adenocarcinomas were grade group 1, PTEN+, pT2. In the first case, the invasive adenocarcinoma was adjacent but nor intermingled with the IDC-P, and a discordance in the immunophenotype between them was outstanding (positivity for ERG in the acinar carcinoma being negative in the IDC-P). In the second case, the foci of adenocarcinoma were distant from the IDC-P. The first patient had not biochemical recurrence after a 34 month follow-up period. Conclusions: This kind of cases supports the existence of an infrequent subtype of IDC-P that could be considered as an in situ neoplasia (AU)

Objetivos: El carcinoma intraductal de la próstata(CIDP) aparece generalmente asociado a adenocarcinomasacinares agresivos, de alto grado. En general se cree que elCIDP representa una forma de diseminación deladenocarcinoma a los ductos prostáticos. En ocasiones elCIDP aparece, sin embargo, sin tumor infiltrante o conadenocarcinomas de bajo grado.Material y Métodos: Presentamos dos pacientes de66 y 75 años, que en las piezas de prostatectomía radicalpresentaron CIDP y focos de adenocarcinoma acinar degrupo de grado bajo.Resultados: Los adenocarcinomas acinares eran degrupo de grado 1, PTEN+, pT2. En el primer caso, eladenocarcinoma se localizaba adyacente, pero noentremezclado, con el CIDP, y destacaba la discordanciaen el inmunofenotipo entre el adenocarcinoma, ERG+, y elCIDP, que era ERG-. En el segundo, los focos de adenocarcinoma se localizaban a distancia del CIDP. Elprimer paciente no ha presentado recidiva bioquímica tras34 meses de seguimiento.Conclusiones: Las características de los casos quepresentamos apoyan la existencia de un subtipoinfrecuente de CIDP que se podría considerar como unaneoplasia in situ. (AU)

Hollow Iron Oxide Nanospheres Obtained through a Combination of Atomic Layer Deposition and Electrospraying Technologies.

In the present study, we report on the successful synthesis of hollow iron oxide nanospheres. The hollow Fe3O4 nanospheres were synthesized following a four-step procedure: electrospraying spherical PVP particles, coating these particles with alumina (Al2O3) and hematite (Fe2O3) through atomic layer deposition and, finally, a thermal reduction process to degrade the polymer (PVP) and convert hematite (Fe2O3) into magnetite (Fe3O4). A structural analysis using X-ray diffraction (XRD) confirmed the effectiveness of the thermal reduction process. A morphological analysis confirmed that the four-step procedure allowed for the obtainment of hollow iron oxide nanospheres, even though the reduction process caused a contraction in the diameter of the particles of almost 300 nm, but did not affect the thickness of the walls of the hollow spheres that remained at approximately 15 nm. Magnetic properties of the hollow iron oxide nanospheres enable their use in applications where the agglomeration of magnetic nanostructures in liquid media is commonly not allowed, such as in drug encapsulation and delivery.

Surface Inspection and Description in Metrology and Tribology-Vol.1.

The primary goal of this Special Issue was to present recent trends in surface inspection and description, from both metrological and tribological points of view [...].

Experimental Study on the Manufacturing of Steel Inclined Walls by Directed Energy Deposition Based on Dimensional and 3D Surface Roughness Measurements.

Robotic-directed energy deposition has attracted the attention of the research community and industry as a process capable of producing large metallic parts. The selection of the manufacturing conditions is a critical step in improving the process efficiency and quality of the produced parts. The present work aims at analyzing the geometry and surface topography of walls built using several conditions and inclination angles, without additional supports except for the substrate. The walls were made of AWS A5.18. ER70S-6 steel using the Wire Arc Additive Manufacturing process. The study used both dimensional and 3D topography measurements to analyze the results. As findings, the travel speed played an important role in the size of the cross-section due to the heat input to the welding zone. Heat accumulation was a critical factor in the size and accuracy of the beads. Moreover, intermediate cooling provided structures with more uniform dimensions, smaller width, and higher layer growth. The inclination of the pieces influenced the width and uniformity of the beads, generating minor imperfections on the downside of the pieces because of gravity.

Effect of Surface Texture on the Structural Adhesive Joining Properties of Aluminum 7075 and TEPEX®.

In the process of continuous improvement of manufacturing processes, this study was developed within the framework of the Ecovoss project, based on the inclusion of lightweight and new materials parts in the automotive sector. The objective was based on the replacement of aluminum welding operations with the option of adhesive operations with other types of materials such as polyamides or, in this case, a TEPEX® composite material (Dynalite 202-c200/50% TYP 13). The aim of this work is to test the best texturing of substrate made in 7075 aluminum specimens manufactured by robotic polishing with an ABB 6640 robot. Another substrate is TEPEX composite. A structural adhesive film AF-163-2 from the 3M company (St Paul, MN, USA) is used, which must be applied according to the manufacturing procedure. The tests carried out are based on the topographic measurement of the surfaces to be joined with an Alicona focus variation microscope, and the uniaxial shear tests of adhesive samples have been analyzed. The texture of the surface failure has been analyzed, and the results confirm a significant correlation between the texture parameters of initial surfaces and maximum shear stress. The expected results should provide a better understanding of the surfaces aimed to optimize the adhesion of the studied materials.

Processing and Testing of Reinforced PA66 Based Composites.

The new requirements in different sectors, such as aerospace, automotive and construction, for lightweight materials have led to an increase in demand for composite materials suitable for use in high rate production processes, such as plastic injection. This makes it necessary to look for matrices and reinforcements that, in addition to being compatible with each other, are also compatible with the injection process. It is in this area of research where the work presented here arises. To meet the two requirements mentioned above, this study contemplates a battery of composite materials obtained by combining PA66 and fiberglass, in different proportions and configuration, both for the preparation of the matrix and for reinforcement. For the elaboration of the matrix, two options have been evaluated, PA66 and PA66 reinforced at 35% with short glass fibre. To obtain reinforcement, six different options have been evaluated; two conventional fiberglass fabrics (each with different density) and four hybrid fabrics obtained from the previous ones by adding PA66 in different configurations (two over-stitched fabrics and two other fabrics). The different composite materials obtained were validated by means of the corresponding adhesion, peeling and resistance tests.

Simple Discriminatory Methodology for Wear Analysis of Cutting Tools: Impact on Work Piece Surface Morphology in Case of Differently Milled Kinetics Steel H13.

Recently, there is growing interest in optimisation of finishing process thanks to the technologies to follow online the wear of cutting tools. In the present paper, one of the cheapest and simplest non-contact methodologies is described in detail and investigated with robustness evaluation. To simulate the finishing operation of a die, in this study, two cavities were designed in AISI H13 steel. Different inserts corresponding to PVD-(Ti,Al)N coated cemented carbide tool were tested. The described methodology is easy to be applied in manufacturing cutting machining with the opportunity to be implemented on machining processes to follow reasonably wear process of cutting tools.

Novel hollow titanium dioxide nanospheres with antimicrobial activity against resistant bacteria.

The search for and synthesis of new antimicrobial nanostructures is important to reduce microbial incidence that induces infectious diseases and to aid in the antibiotic resistance crisis, which are two of the most pressing issues in global public health. In this work, novel, hollow, calcined titanium dioxide nanospheres (CSTiO2) were successfully synthesized for the first time through the combination of electrospinning and atomic layer deposition techniques. Poly(vinylpyrrolidone) (PVP) electrosprayed spherical particles were double-coated with alumina and titanium dioxide, and after a calcination process, hollow nanospheres were obtained with a radius of approximately 345 nm and shell thickness of 17 nm. The structural characterization was performed using electron microscopy, and X-ray diffraction and small-angle X-ray diffraction evidenced an anatase titanium dioxide crystalline structure. Thermogravimetric analysis and Fourier-transform infrared spectroscopy studies demonstrated the absence of polymer residue after the calcination process. The antimicrobial properties of the developed CSTiO2 hollow nanospheres were evaluated against different bacteria, including resistant E. coli and S. aureus strains, and when compared to commercial TiO2 nanoparticles, CSTiO2 nanospheres exhibited superior performance. In addition, the positive effect of UV irradiation on the antimicrobial activity was demonstrated.

Magnetic properties of Fe3O4 antidot arrays synthesized by AFIR: atomic layer deposition, focused ion beam and thermal reduction.

Magnetic films of magnetite (Fe3O4) with controlled defects, so-called antidot arrays, were synthesized by a new technique called AFIR. AFIR consists of the deposition of a thin film by atomic layer deposition, the generation of square and hexagonal arrays of holes using focused ion beam milling, and the subsequent thermal reduction of the antidot arrays. Magnetic characterizations were carried out by magneto-optic Kerr effect measurements, showing the enhancement of the coercivity for the antidot arrays. AFIR opens a new route to manufacture ordered antidot arrays of magnetic oxides with variable lattice parameters.