Development of a New Manufacturing Route by Direct Laser Metal Deposition With NiCrSiFeB Alloys to Replace Cobalt in Aeronautical Components

Nickel-based NiCrSiFeB alloy (Ni-Cr-Si-B self-fluxing family) are excellent candidates for replacing Cobalt-based alloys in aeronautical components such as sealing rings, valve seats, sliding bearing seats, etc. In this type of components, commonly manufactured by centrifugal casting and conventional processes, high temperature wear and stiffness under complex thermo-mechanical stresses cause lack of sealing and an increase in the wear rate. Metal additive manufacturing by direct laser metal deposition with powder (p-LMD) is presented as a potential manufacturing route for the complex processing of this type of alloys. This research work deals with the development of a new manufacturing route using p-LMD that ranges from the proper selection of the chemical composition for the starting powders, the development of the LMD process parameters to tackle the challenges associated to the wide solidification range and crack susceptibility of Ni-Cr-Si-B alloys, its monitoring and control, as well as the post-processing required to achieve the manufacture of aeronautical components. In this work, the porosity analysis, as-built microstructure, hardness at room temperature and at high temperature, and the strengthening mechanisms have been studied in cylinders manufactured with different chemical composition grades and LMD process parameter sets (slow, normal and fast deposition speed)

Assessment of vitamin D status and parathyroid hormone during a combined intervention for the treatment of childhood obesity

Background: Obesity is associated with vitamin D deficiency. The aim of this work is to analyze the changes in vitamin D status and PTH levels in a group of children with obesity receiving combined intervention program in order to get BMI status reduction. Methods: Longitudinal study in 119 children with obesity, aged 9.1–13.9 years, included in a 1-year combined dietarybehavioral-physical activity intervention. Anthropometric measurements (weight, height, BMI and fat mass index) were registered every 3 months and blood testing (calcium, phosphorous, 25(OH)D and PTH) were collected at the beginning and after 12 months of follow-up. A control group was recruited (300 healthy children, aged 8.1–13.9 years). The criteria of the US Endocrine Society were used for the definition of hypovitaminosis D. Results: Vitamin D deficiency was significantly higher in obesity group (31.1 vs. 14%). There was negative correlation between 25(OH)D and fat mass index (r = −0.361, p = 0.001). Patients with BMI reduction throughout combined intervention were 52 (43.7%). There was a significant increase in the prevalence of hypovitaminosis D in patients without BMI reduction at the end of follow-up, but in those patients with BMI reduction there was no changes of vitamin D status. Conclusions: Obesity increases the prevalence of suboptimal vitamin D status, and a BMI status reduction in children with obesity may be required to at least stabilize vitamin D status

Effects of the application of a prolonged combined intervention on body composition in adolescents with obesity

Background: The aim of this study is to describe the effects of a prolonged dietary-behavioral-physical activity intervention (24 months) on body composition in a group of adolescents with obesity. Methods: Longitudinal study in 196 individuals with obesity (86 boys and 110 girls) aged 10.1–14.9 years that completed a prolonged combined intervention (24 months). Values for weight, height, skinfold thickness, waist circumference, BMI, body fat, fat mass index (FMI) and fat-free mass index (FFMI) were registered or calculated. A good response to treatment was reported when a BMI z-score reduction of greater than or equal to 0.5 units of the initial value occurred after 24 month of follow up. Results: A good response after 24 months of follow-up reached 58.2% (n = 114). In boys with obesity and BMI status improvement, weight z-score, BMI z-score, body fat, and FMI significantly decreased (p < 0.05). In girls with obesity and BMI status improvement, weight z-score, BMI z-score, waist circumference, waist z-score, body fat and FMI significantly decreased (p < 0.05). In both sexes the height and FFMI increased significantly (p < 0.05). The multiple logistic regression analysis showed that girls and younger age were associated with BMI status improvement; concurrently, the place of residence (urban or rural) and degree of obesity were not associated with BMI status improvement. Conclusion: The application of long-term combined strategies in the treatment of childhood obesity seems to be effective. As BMI decreases, a reduction in fat mass is also detected, with evident sexual dimorphism, in the absence of changes in fat-free mass and, consequently, in longitudinal growing

Optimization of Thin Walls with Sharp Corners in SS316L and IN718 Alloys Manufactured with Laser Metal Deposition

In this work, the manufacture of thin walls with sharp corners has been optimized by adjusting the limits of a 3-axis cartesian kinematics through data recorded and analyzed off-line, such as axis speed, acceleration and the positioning of the X and Y axes. The study was carried out with two powder materials (SS316L and IN718) using the directed energy deposition process with laser. Thin walls were obtained with 1 mm thickness and only one bead per layer and straight/sharp corners at 90&deg;. After adjusting the in-position parameter G502 for positioning precision on the FAGOR 8070 CNC system, it has been possible to obtain walls with minimal accumulation of material in the corner, and with practically constant layer thickness and height, with a radii of internal curvature between 0.11 and 0.24 mm for two different precision configuration. The best results have been obtained by identifying the correct balance between the decrease in programmed speed and the precision in the positioning to reach the point defined as wall corner, with speed reductions of 29% for a programmed speed of 20 mm/s and 61% for a speed of 40 mm/s. The walls show minimal defects such as residual porosities, and the microstructure is adequate

Prevalencia de hipovitaminosis D y factores asociados en la edad infantojuvenil

Resumen: Objetivo: Analizar la prevalencia de hipovitaminosis D y factores asociados en escolares y adolescentes residentes en una región del norte peninsular. Diseño: Estudio descriptivo transversal (muestreo de conveniencia). Emplazamiento: Atención primaria. Participantes: Fueron incluidos 602 sujetos sanos de raza caucásica con edades comprendidas entre 3,1 y 15,4 años. Mediciones principales: Se ha calculado la prevalencia de hipovitaminosis D (variable dependiente) según los criterios de la US Endocrine Society: deficiencia (calcidiol < 20 ng/ml), insuficiencia (calcidiol: 20-29 ng/ml) y suficiencia (calcidiol ≥ 30 ng/ml). Se han registrado como variables independientes: sexo, edad, índice de masa corporal, lugar de residencia y estación del año, analizándose su asociación con la hipovitaminosis D mediante regresión logística múltiple. Resultados: La prevalencia de hipovitaminosis D era del 60,4% (insuficiencia: 44,6%; deficiencia: 15,8%). Las variables asociadas con la hipovitaminosis D eran el sexo femenino (OR: 1,6; IC 95%: 1,1-2,3), la edad puberal (OR: 1,8; IC 95%: 1,2-2,6), las estaciones de otoño (OR: 9,5; IC 95%: 4,8-18,7), invierno (OR: 8,8; IC 95%: 4,5-17,5) y primavera (OR: 13,2; IC 95%: 6,4-27,5), el entorno urbano (OR:1,6; IC 95%: 1,1-2,2) y la obesidad severa (OR: 4,4; IC 95%: 1,9-10,3). Conclusiones: En la población infantojuvenil existe una alta prevalencia de hipovitaminosis D, y los factores asociados son el sexo femenino, la edad puberal, el otoño, el invierno y la primavera, la obesidad severa y el entorno urbano. Habría que considerar la necesidad de administrar suplementos vitamínicos o ingerir mayores cantidades de sus fuentes dietéticas naturales y/o alimentos enriquecidos durante los meses de otoño, invierno y primavera. Abstract: Objective: To analyse the prevalence of hypovitaminosis D and associated factors in school children and adolescents living in a region of northern Spain. Design: Cross-sectional study (convenience sampling). Setting: Primary Health Care. Participants: A total of 602 Caucasian individuals (aged 3.1 to 15.4 years) were included in the study. Main measurements: Prevalence of hypovitaminosis D were calculated (dependent variable). Hypovitaminosis D is defined according to the US Endocrine Society criteria: deficiency (calcidiol < 20 ng/mL), insufficiency (calcidiol: 20-29 ng/mL), and sufficiency (calcidiol ≥ 30 ng/mL). Gender, age, body mass index, residence, and season of the year were recorded (independent variables), and their association with hypovitaminosis D was analysed by multiple regression. Results: The prevalence of hypovitaminosis D was 60.4% (insufficiency: 44.6%; deficiency: 15.8%). Multivariate analysis showed that factors associated to hypovitaminosis D were being female (OR: 1.6; 95% CI: 1.1-2.3), pubertal age (OR: 1.8; 95% CI: 1.2-2.6), autumn (OR: 9.5; 95% CI: 4.8-18.7), winter (OR: 8.8; 95% CI: 4.5-17.5) and spring time (OR: 13.2; 95% CI: 6.4-27.5), living in urban areas (OR:1.6; CI 95%: 1.1-2.2), and severe obesity (OR: 4.4; 95% CI: 1.9-10.3). Conclusions: There is a high prevalence of hypovitaminosis D in juvenile populations. being female, pubertal age, autumn, winter and spring seasons, severe obesity, and living in urban areas are factors associated to hypovitaminosis D. Consideration should be given to the administration of vitamin supplements and/or the increase in the ingestion of natural vitamin D dietary sources. Palabras clave: Adolescentes, Calcidiol, Escolares, Factores asociados, Hipovitaminosis D, Keywords: Adolescents, Calcidiol, School children, Associated factors, Hypovitaminosis

Assessment of vitamin D status and parathyroid hormone during a combined intervention for the treatment of childhood obesity

Background: Obesity is associated with vitamin D deficiency. The aim of this work is to analyze the changes in vitamin D status and PTH levels in a group of children with obesity receiving combined intervention program in order to get BMI status reduction. Methods: Longitudinal study in 119 children with obesity, aged 9.1–13.9 years, included in a 1-year combined dietarybehavioral-physical activity intervention. Anthropometric measurements (weight, height, BMI and fat mass index) were registered every 3 months and blood testing (calcium, phosphorous, 25(OH)D and PTH) were collected at the beginning and after 12 months of follow-up. A control group was recruited (300 healthy children, aged 8.1–13.9 years). The criteria of the US Endocrine Society were used for the definition of hypovitaminosis D. Results: Vitamin D deficiency was significantly higher in obesity group (31.1 vs. 14%). There was negative correlation between 25(OH)D and fat mass index (r = −0.361, p = 0.001). Patients with BMI reduction throughout combined intervention were 52 (43.7%). There was a significant increase in the prevalence of hypovitaminosis D in patients without BMI reduction at the end of follow-up, but in those patients with BMI reduction there was no changes of vitamin D status. Conclusions: Obesity increases the prevalence of suboptimal vitamin D status, and a BMI status reduction in children with obesity may be required to at least stabilize vitamin D status

Effects of the application of a prolonged combined intervention on body composition in adolescents with obesity

Background: The aim of this study is to describe the effects of a prolonged dietary-behavioral-physical activity intervention (24 months) on body composition in a group of adolescents with obesity. Methods: Longitudinal study in 196 individuals with obesity (86 boys and 110 girls) aged 10.1–14.9 years that completed a prolonged combined intervention (24 months). Values for weight, height, skinfold thickness, waist circumference, BMI, body fat, fat mass index (FMI) and fat-free mass index (FFMI) were registered or calculated. A good response to treatment was reported when a BMI z-score reduction of greater than or equal to 0.5 units of the initial value occurred after 24 month of follow up. Results: A good response after 24 months of follow-up reached 58.2% (n = 114). In boys with obesity and BMI status improvement, weight z-score, BMI z-score, body fat, and FMI significantly decreased (p < 0.05). In girls with obesity and BMI status improvement, weight z-score, BMI z-score, waist circumference, waist z-score, body fat and FMI significantly decreased (p < 0.05). In both sexes the height and FFMI increased significantly (p < 0.05). The multiple logistic regression analysis showed that girls and younger age were associated with BMI status improvement; concurrently, the place of residence (urban or rural) and degree of obesity were not associated with BMI status improvement. Conclusion: The application of long-term combined strategies in the treatment of childhood obesity seems to be effective. As BMI decreases, a reduction in fat mass is also detected, with evident sexual dimorphism, in the absence of changes in fat-free mass and, consequently, in longitudinal growing