Microhardness and Microstructure Analysis of the LPBF Additively Manufactured 18Ni300.

This research focuses on analysing the 18Ni300 maraging steel produced through laser powder bed fusion. Specifically, it aims to examine the phase components using X-ray diffraction, the microstructure through scanning electron microscopy, and the hardness of the different structures present in the manufactured material. The primary goal is to meticulously analyse the material and its microstructures. By doing so, a correlation between the hardness and each structure type, be it cellular or columnar, can be established. This will allow us to pinpoint any defects in the material before any surface chemical treatment is carried out and facilitate a thorough examination of its microstructure. A consistent pattern emerges across the samples through systematic measurement of microhardness distribution in various locations and detailed examination of the structure. The findings of the study reveal that the hardness of cellular and columnar structures exhibits a significant variation based on the location of the measurement about cell boundaries. The hardness value is notably higher in the combination of cellular and multiple layers, as the data indicate.

Measuring absorbed energy in the human auditory system using finite element models: A comparison with experimental results.

BACKGROUND: There are different ways to analyze energy absorbance (EA) in the human auditory system. In previous research, we developed a complete finite element model (FEM) of the human auditory system. OBJECTIVE: In this current work, the external auditory canal (EAC), middle ear, and inner ear (spiral cochlea, vestibule, and semi-circular canals) were modelled based on human temporal bone histological sections. METHODS: Multiple acoustic, structure, and fluid-coupled analyses were conducted using the FEM to perform harmonic analyses in the 0.1-10 kHz range. Once the FEM had been validated with published experimental data, its numerical results were used to calculate the EA or energy reflected (ER) by the tympanic membrane. This EA was also measured in clinical audiology tests which were used as a diagnostic parameter. RESULTS: A mathematical approach was developed to calculate the EA and ER, with numerical and experimental results showing adequate correlation up to 1 kHz. Another published FEM had adapted its boundary conditions to replicate experimental results. Here, we recalculated those numerical results by applying the natural boundary conditions of human hearing and found that the results almost totally agreed with our FEM. CONCLUSION: This boundary problem is frequent and problematic in experimental hearing test protocols: the more invasive they are, the more the results are affected. One of the main objectives of using FEMs is to explore how the experimental test conditions influence the results. Further work will still be required to uncover the relationship between middle ear structures and EA to clarify how to best use FEMs. Moreover, the FEM boundary conditions must be more representative in future work to ensure their adequate interpretation.

Tomography of Laser Powder Bed Fusion Maraging Steel.

The presence of defects in additive manufactured maraging steel is a widespread problem as its dependence on processing parameters significantly influences it. Using X-ray computed tomography, along with optical microscope data limited to 2D images, quantifies the internal porosity present on a compact tension sample typically employed in fatigue testing. The primary goal of this research is to analyse the pores obtained after the fabrication of a compact tension sample and their main definition parameters, such as sphericity, aspect ratio, surface, and volume, and obtain validation of which method is valid for each of the parameters analysed. The current study aims to enhance the understanding of defects in maraging steel samples through non-destructive 3D analysis. Conventional 2D analyses are limited to surface measurements, providing incomplete information. The proposed method will provide a comprehensive understanding of the defects inside the maraging steel sample, thereby improving the reliability of this material for further applications. This study will contribute to academic and industrial communities by providing a novel approach to analysing maraging steel samples and, ultimately, developing improved materials for various applications. The study's findings reveal that most pores are produced by gases that are trapped in the fabrication process, and keyhole pores only appear near the surface.

Influence of Porosity on Fatigue Behaviour of 18Ni300 Steel SLM CT Specimens at Various Angles.

In order to improve understanding of the fatigue behaviour in additive manufactured samples, this research delves into the challenging interplay between building parameters, particularly fabrication angles, and the presence of pores. The primary objective is to explore the characterisation of these pores and unravel their relationship with the fatigue properties of the material under investigation. Through a systematic analysis of porosity distribution in various fabrication orientations, supplemented by a detailed examination of the elemental dispersion around specific porous structures using energy-dispersive X-ray spectroscopy, a consistent behavioural pattern emerges across the samples. In assessing fatigue behaviour, an examination of the variables reveals that only area and aspect ratio significantly influence the behaviour of the samples. Such studies can contribute substantially to academic research in the field of material science and engineering.

A Literature Review of Incorporating Crack Tip Plasticity into Fatigue Crack Growth Models.

This paper presents an extensive literature review focusing on the utilisation of crack tip plasticity as a crucial parameter in determining and enhancing crack growth models. The review encompasses a comprehensive analysis of various methodologies, predominantly emphasising numerical simulations of crack growth models while also considering analytical approaches. Although experimental investigations are not the focus of this review, their relevance and interplay with numerical and analytical methods are acknowledged. The paper critically examines these methodologies, providing insights into their advantages and limitations. Ultimately, this review aims to offer a holistic understanding of the role of crack tip plasticity in the development of effective crack growth models, highlighting the synergies and gaps between theoretical, experimental, and simulation-based approaches.

Effect of high-pressure homogenization on different matrices of food supplements.

There is a growing demand for food supplements containing high amounts of vitamins, phenolic compounds and mineral content that provide health benefits. Those functional compounds have different solubility properties, and the maintenance of their compounds and the guarantee of their homogenic properties need the application of novel technologies. The quality of different drinkable functional foods after thermal processing (0.1 MPa) or high-pressure homogenization under two different conditions (80 MPa, 33 ℃ and 120 MPa, 43 ℃) was studied. Physicochemical characteristics and sensory qualities were evaluated throughout the six months of accelerated storage at 40 ℃ and 75% relative humidity (RH). Aroma and color were better maintained in high-pressure homogenization-treated samples than the thermally treated ones, which contributed significantly to extending their shelf life. The small particle size obtained after high-pressure homogenization treatments caused differences in turbidity and viscosity with respect to heat-treated samples. The use of high-pressure homogenization, more specifically, 120 MPa, provided active ingredient homogeneity to ensure uniform content in functional food supplements. Although the effect of high-pressure homogenization can be affected by the food matrix, high-pressure homogenization can be implemented as an alternative to conventional heat treatments in a commercial setting within the functional food supplement or pharmaceutical industry.

Good urodynamic practices in a non-specialized center: quality control analysis.

OBJECTIVES: To review the quality of urodynamic studies performed in one Center in order to assess adherence to the ICS Good Urodynamic Practice Guidelines. METHODS: Sixty-two consecutive urodynamic studies performed between March 2012 and May 2013 were retrospectively reviewed. We followed a list of common features to analyze all records. RESULTS: 10.17% of the studies showed a significant drop in Pabd not mentioned in the study report. We found straining in 15.25% of the traces that was recognized and informed in the reports. We did not find many equipment artifacts, only pump vibrations. Uroflowmetry performed previously to the test is very important to compare its results with the ones obtained at the pressure- flow study. 50.8% of the studies had a non-valuable uroflowmetry. CONCLUSIONS: The high rate of non-valuable uroflowmetries was in most of the cases due to an insufficient voiding volume. We think we meet very good standards although this is not a reference unit; nevertheless we still need to improve in many aspects.

Las buenas prácticas en urodinámica como un indicador de calidad en un Servicio no especializado / Good urodynamic practices in a non-specialized center: quality control analysis

OBJETIVO: Evaluación de estudios urodinámicos realizados en un Centro no especializado para valorar su calidad en relación con las Guías de Buenas Prácticas en Urodinámica de la Sociedad Internacional de Incontinencia. MÉTODOS: Se analizaron 62 estudios urodinámicos realizados entre marzo 2012 y mayo 2013 de forma retrospectiva. Se empleó para ello una serie de parámetros característicos comunes en todos los trazados. Se realizó una uroflujometría previa para su comparación posterior con la del estudio presión-flujo. RESULTADO: El 10,17% de los trazados mostró un descenso significativo de la Pabd no informado en el estudio. En el 15,25% se constató "presión al orinar", la cual fue reconocida e informada en las conclusiones. No hemos encontrado mayores artefactos, salvo vibraciones por la bomba. Como hallazgo más relevante, el 50,8% de los estudios presentaba una uroflujometría previa no vaporable. CONCLUSIONES: La elevada tasa de uroflujometrías no valorables fue en la mayoría de los casos por un volumen miccional insuficiente. Creemos que alcanzamos una elevada performance en la realización de nuestros estudios, a pesar de no tratarse de un centro especializado. El análisis retrospectivo nos permite detectar nuestros errores para poder tomar las medidas de corrección pertinentes

OBJECTIVES: To review the quality of urodynamic studies performed in one Center in order to assess adherence to the ICS Good Urodynamic Practice Guidelines. METHODS: Sixty-two consecutive urodynamic studies performed between March 2012 and May 2013 were retrospectively reviewed. We followed a list of common features to analyze all records. RESULTS: 10.17% of the studies showed a significant drop in Pabd not mentioned in the study report. We found straining in 15.25% of the traces that was recognized and informed in the reports. We did not find many equipment artifacts, only pump vibrations. Uroflowmetry performed previously to the test is very important to compare its results with the ones obtained at the pressure-flow study. 50.8% of the studies had a non-valuable uroflowmetry. CONCLUSIONS: The high rate of non-valuable uroflowmetries was in most of the cases due to an insufficient voiding volume. We think we meet very good standards although this is not a reference unit; nevertheless we still need to improve in many aspects

[Cutaneous metastases from transitional cell carcinoma of the bladder producing beta-HCG]. / Metástasis cutáneas de un carcinoma transicional vesical productor de beta-HCG.

In spite of the high incidence of transitional cell carcinoma, cutaneous metastases are infrequent, especially when they are the first sign of metastatic spread, with a low survival rate. Thirty five per cent of transitional cell carcinoma of the bladder have ectopic beta- human chorionic gonadotropin (beta-HCG) production. It has been related with high grade tumors, advanced stage, metastatic disease, radioresistent tumors and low survival rate because of its effect as a growth modulator with a probably antagonist action in the apoptotic cascade. We present a thirty six years old woman affected by a transitional cell carcinoma of the bladder producing beta-HCG that showed two cutaneous metastases as first sign of metastatic disease. The exceptional coincidence of these two circumstances announced a very aggressive tumor behaviour and bad prognostic, with a quickly multiple metastatic dissemination including a pericardic metastases.

Metástasis cutáneas de un carcinoma transicional vesical productor de β-HCG / Cutaneous metastases from transitional cell carcinoma of the bladder producing β-HCG

A pesar de la alta incidencia de carcinoma transicional vesical, la aparición de metástasis cutáneas es infrecuente, más aún como primera manifestación de diseminación metastásica, asociándose a una pobre supervivencia. La producción ectópica de beta-gonadotropina coriónica humana (β-HCG) ocurre en un 35% de los carcinomas transicionales vesicales y se ha correlacionado con tumores de alto grado, estadios avanzados, enfermedad metastásica, falta de respuesta a la radioterapia y pobre supervivencia, en virtud de su efecto regulador del crecimiento tumoral por un probable efecto antagonista sobre receptores de la cascada apoptótica. Presentamos el caso de una paciente de 36 años con carcinoma transicional de vejiga productor de β-HCG que presentó dos metástasis cutáneas como primer signo de enfermedad a distancia. Ambas circunstancias asociadas de forma excepcional identificaron un comportamiento muy agresivo del tumor y su mal pronóstico, desarrollando a corto plazo un estallido metastático a múltiples niveles incluyendo una metástasis pericárdica (AU)

In spite of the high incidence of transitional cell carcinoma, cutaneous metastases are infrequent, especially when they are the first sign of metastatic spread, with a low survival rate. Thirty five per cent of transitional cell carcinoma of the bladder have ectopic beta- human chorionic gonadotropin (β-HCG) production. It has been related with high grade tumors, advanced stage, metastatic disease, radio resistent tumors and low survival rate because of its effect as a growth modulator with a probably antagonist action in the apoptotic cascade.We present a thirty six years old woman affected by a transitional cell carcinoma of the bladder producing β-HCG that showed two cutaneous metastases as first sign of metastatic disease. The exceptional coincidence of these two circumstances announced a very aggressive tumor behaviour and bad prognostic, with a quickly multiple metastatic dissemination including a pericardic metastases (AU)