Determination and Analysis of Residual Stresses Induced by High Speed Milling Using a Micro-indent Method

Abstract: The purpose of this work is to determine and analyze residual stress normal components and anisotropy degrees introduced by high-speed milling in specimens of AA 6082-T6 and AA 7075-T6 aluminum alloys. At each machined sample, the climb and conventional cutting zones were evaluated and compared. This paper includes a comprehensive study of thermal and mechanical effects associated with the residual stress introduction. For normal components determination, an optimized micro-indent method was used. Each measurement sequence from this approach was performed using a high accuracy measuring machine and classified according to thermal deviations measured. The residual displacements were determined with an absolute error down to ±300 nm. The normal components analysis allowed to infer the strong influence of the rolling process previous to high-speed milling and besides, the stress levels associated with thermal effects (higher in AA 7075-T6). Finally, the lower residual stress anisotropy degrees in both materials observed in the conventional cutting zone would indicate more homogenous local plastic stretching in this region for all planar directions.Research Journal of Applied Sciences, Engineering and TechnologyFil: Vottero, S. Departamento de Ingeniería Electromecánica-Departamento de Ingeniería Industrial, Facultad Regional Rafaela, Universidad Tecnológica Nacional, Acuña 49, 2300 Rafaela, Argentina.Fil: Mammana, C. A. Departamento de Ingeniería Electromecánica-Departamento de Ingeniería Industrial, Facultad Regional Rafaela, Universidad Tecnológica Nacional, Acuña 49, 2300 Rafaela, Argentina.Fil: Guidobono, A. P. M. División Metrología Dimensional, Centro Regional Rosario (INTI), Ocampo y Esmeralda, 2000 Rosario, Argentina.Peer Reviewe

Determination and Analysis of Residual Stresses Induced by High Speed Milling Using a Micro-indent Method

The purpose of this work is to determine and analyze residual stress normal components and anisotropy degrees introduced by high-speed milling in specimens of AA 6082-T6 and AA 7075-T6 aluminum alloys. At each machined sample, the climb and conventional cutting zones were evaluated and compared. This paper includes a comprehensive study of thermal and mechanical effects associated with the residual stress introduction. For normal components determination, an optimized micro-indent method was used. Each measurement sequence from this approach was performed using a high accuracy measuring machine and classified according to thermal deviations measured. The residual displacements were determined with an absolute error down to ±300 nm. The normal components analysis allowed to infer the strong influence of the rolling process previous to high-speed milling and besides, the stress levels associated with thermal effects (higher in AA 7075-T6). Finally, the lower residual stress anisotropy degrees in both materials observed in the conventional cutting zone would indicate more homogenous local plastic stretching in this region for all planar directions.Fil: Vottero, S.. Universidad Tecnológica Nacional. Facultad Regional Rafaela; ArgentinaFil: Diaz, Felipe Victor. Universidad Tecnológica Nacional. Facultad Regional Rafaela; ArgentinaFil: Mammana, Claudio Alejandro. Universidad Tecnológica Nacional. Facultad Regional Rafaela; ArgentinaFil: Guidobono, A.. Instituto Nacional de Tecnología Industrial; Argentin

A new variant in signal peptide of the human luteinizing hormone receptor (LHCGR) affects receptor biogenesis causing leydig cell hypoplasia

The human luteinizing hormone/chorionic gonadotropin receptor (LHCGR) plays a fundamental role in male and female reproduction. In males, loss-of-function mutations in LHCGR have been associated with distinct degrees of impairment in pre- and postnatal testosterone secretion resulting in a variable phenotypic spectrum, classified as Leydig cell hypoplasia (LCH) type 1 (complete LH resistance and disorder of sex differentiation) and type 2 (partial LH resistance with impaired masculinization and fertility).Here, we report the case of an adolescent who came to the pediatric endocrinologist at the age of 12 years old for micropenis and cryptorchidism. Testis biopsy showed profound Leydig cell hypoplasia and absent germinal line elements (Sertoli-only syndrome). The sequence analysis of the LHCGR gene showed the presence of a compound heterozygosity, being one variation, c.1847C>A p.S616Y, already described in association to Hypergonadotropic Hypogonadism (HH), and the other, c.29 C>T p.L10P, a new identified variant in the putative signal peptide of LHCGR. Functional and structural studies provide first evidence that LHCGR have a functional and cleavable signal peptide required for receptor biogenesis. Moreover, we demonstrate the pathogenic role of the novel p.L10P allelic variant, which has to be considered a loss-of-function mutation significantly contributing, in compound heterozygosity with p.S616Y, to the Leydig cell hypoplasia type 2 observed in our patient

Aplicación de la destilación molecular de camino corto a la separación de macromoléculas de aceites vegetales

Se han desarrollado ensayos experimentales a escala piloto para concentrar etil ésteres de ácidos grasos obtenidos por transesterificación de aceites vegetales comestibles. Los mismos se llevaron a cabo con el objetivo de concentrar los tipos poliinsaturados de C18, en particular el correspondiente al alfa-linolénico (ALA), dado su interés de comercialización a partir de dichos aceites, a diferencia de otros compuestos de interés como los ácidos eicosapentaenoico (EPA) y docosahexaenoico (DHA), presentes de manera natural en otros derivados de productos marinos. Tales ensayos constituyen una de las etapas principales de un desarrollo tecnológico que comprende el tratamiento integral del proceso de obtención de etil ésteres de ácidos grasos a partir aceites vegetales comestibles no tradicionales, en el contexto de un convenio específico establecido entre la Facultad Regional Villa María de la UTN y la empresa Porta Hnos S.A. Se evaluaron diferentes condiciones de operación, principalmente temperaturas y niveles de vacío, a efectos de optimizar la separación deseada utilizando un destilador molecular de camino corto facilitado por la empresa. La concentración del producto se llevó a cabo operando en múltiples etapas. La primera destilación parte del material transesterificado obtenido en una instancia previa, separándose los etil ésteres -EE- de un residuo constituido por otros suproductos de distintos tipos y características (no etil ésteres- NEE). Luego los EE fueron destilados sucesivamente hasta alcanzar un producto concentrado resultante de cortes intermedios entre livianos y pesados, los que se recuperaron luego como subproducto. Se empleó cromatografía en fase gaseosa para su cuantificación. Como resultados se menciona la determinación de las condiciones de operación que permiten llevar el proceso a escala productiva y la obtención de un producto acorde a requerimientos.Fil: Bragagnini Napolitado, Virginia M. Universidad Tecnológica Nacional. Facultad Regional Villa María. GISIQ; Argentina.Fil: Vottero, Tomás J. Universidad Tecnológica Nacional. Facultad Regional Villa María. GISIQ; Argentina.Fil: Magnani, Ezequiel. Universidad Tecnológica Nacional. Facultad Regional Villa María. GISIQ; Argentina.Fil: Toselli, Luis A. Universidad Tecnológica Nacional. Facultad Regional Villa María. GISIQ; Argentina.Peer Reviewe

Prevalence of pathogenetic MC4R mutations in Italian children with early onset obesity, tall stature and familial history of obesity.

BackgroundMelanocortin-4-receptor (MC4R) mutations represent the most frequent genetic cause of non-syndromic early onset obesity. Children carrying MC4R mutations seem to show a particular phenotype characterized by early onset, severe obesity and high stature. To verify whether MC4R mutations are associated with this particular phenotype in the Italian pediatric population, we decided to screen the MC4R gene in a group of obese children selected on the basis of their phenotype.MethodsTo perform this study, a multicentric approach was designed. Particularly, to be enrolled in the study subjects needed to meet the following criteria: Body mass index ≥ 3 deviation scores according to age and sex, familiar history of obesity (at least one parent obese), obesity onset before the 10 years old, height ≥ 2 deviation scores. The coding region of MC4R gene was screened in 240 obese children (mean age 8.3 ± 3.1, mean BMI 30.8 ± 5.4) and in 200 controls (mean age 8.1 ± 2.8; mean BMI 14.2 ± 2.5).ResultsThree mutations have been found in five obese children. The S127L (C380T), found in three unrelated children, had been described and functionally characterized previously. The Q307X (C919T) and the Y332H (T994C) mutations were found in two patients. Functional studies showed that only Q307X impaired protein function.ConclusionThe low prevalence of MC4R mutations (1.6%) in this group of obese children selected according to the obesity degree, the tall stature and the family history of obesity was similar to the prevalence observed in previous screenings performed in obese adults and in not phenotypically selected obese children

Relationship of CYP21A2 genotype and serum 17-hydroxyprogesterone and cortisol levels in a large cohort of Italian children with premature pubarche.

ObjectivePremature pubarche (PP) is the most frequent sign of nonclassic congenital adrenal hyperplasia (NCCAH) due to 21-hydroxylase deficiency in childhood. The aim of this study was to assess the relationship between the CYP21A2 genotype and baseline and ACTH-stimulated 17-hydroxyprogesterone (17-OHP) and cortisol serum levels in patients presenting with PP.Patients and methodsA total of 152 Italian children with PP were studied. Baseline and ACTH-stimulated 17-OHP and cortisol serum levels were measured and CYP21A2 gene was genotyped in all subjects.ResultsBaseline and ACTH-stimulated serum 17-OHP levels were significantly higher in NCCAH patients than in both heterozygotes and children with idiopathic PP (IPP). Of the patient population, four NCCAH patients (7.3%) exhibited baseline 17-OHP values &lt;2 ng/ml (6 nmol/l). An ACTH-stimulated 17-OHP cutoff level of 14 ng/ml (42 nmol/l) identified by the receiver-operating characteristics curves showed the best sensitivity (90.9%) and specificity (100%) in distinguishing NCCAH patients. This value, while correctly identifying all unaffected children, missed 9% of affected individuals. Cortisol response to ACTH stimulation was &lt;18.2 μg/dl (500 nmol/l) in 14 NCCAH patients (28%) and none of the heterozygotes or IPP children. Among the 55 NCCAH patients, 54.5% were homozygous for mild CYP21A2 mutations, 41.8% were compound heterozygotes for one mild and one severe CYP21A2 gene mutations, and 3.6% had two severe CYP21A2 gene mutations.ConclusionIn children with PP, baseline 17-OHP levels are not useful to rule out the diagnosis of NCCAH, which is accomplished by means of ACTH testing only. The different percentages of severe and mild CYP21A2 gene mutations found in PP children compared with adult NCCAH patients is an indirect evidence that the enzyme defect is under-diagnosed in childhood, and it might not lead to the development of hyperandrogenic symptoms in adulthood. Stress-dose glucocorticoids should be considered in patients with suboptimal cortisol response to ACTH stimulation.</jats:sec