Effect of Industrial Heat Treatment and Barrel Finishing on the Mechanical Performance of Ti6Al4V Processed by Selective Laser Melting

Additive manufacturing is now capable of delivering high-quality, complex-shaped metallic components. The titanium alloy Ti6Al4V is an example of a printable metal being broadly used for advanced structural applications. A sound characterization of static mechanical properties of additively manufactured material is crucial for its proper application, and here specifically for Ti6Al4V. This includes a complete understanding of the influence of postprocess treatment on the material behavior, which has not been reached yet. In the present paper, the postprocess effects of surface finish and heat treatment on the mechanical performance of Ti6Al4V after selective laser melting were investigated. Some samples were subjected to barrel finishing at two different intensities, while different sets of specimens underwent several thermal cycles. As a reference, a control group of specimens was included, which did not undergo any postprocessing. The treatments were selected to be effective and easy to perform, being suitable for real industrial applications. Tensile tests were performed on all the samples, to obtain yield stress, ultimate tensile strength and elongation at fracture. The area reduction of the barrel-finished samples, after being tested, was measured by using a 3D scanner, as a further indication of ductility. Experimental results are reported and discussed, highlighting the effect of postprocessing treatments on the mechanical response. We then propose the optimal postprocessing procedure to enhance ductility without compromising strength, for structures manufactured from Ti6Al4V with selective laser melting

Additive manufacturing for lightweighting satellite platform

Lightweight structures with an internal lattice infill and a closed shell have received a lot of attention in the last 20 years for satellites, due to their improved stiffness, buckling strength, multifunctional design, and energy absorption. The geometrical freedom typical of Additive Manufacturing allows lighter, stiffer, and more effective structures to be designed for aerospace applications. The Laser Powder Bed Fusion technology, in particular, enables the fabrication of metal parts with complex geometries, altering the way the mechanical components are designed and manufactured. This study proposed a method to re-design the original satellite structures consisting of walls and ribs with an enclosed lattice design. The proposed new structures must comply with restricted requirements in terms of mechanical properties, dimensional accuracy, and weight. The most challenging is the first frequency request which the original satellite design, based on traditional fabrication, does not satisfy. To overcome this problem a particular framework was developed for locally thickening the critical zones of the lattice. The use of the new design permitted complying with the dynamic behavior and to obtain a weight saving maintaining the mechanical properties. The Additive Manufacturing fabrication of this primary structure demonstrated the feasibility of this new technology to satisfy challenging requests in the aerospace field

Role of targeted agents in neuroendocrine tumors: Results from a meta-analysis

5noBACKGROUND: Several randomized phase III trials in neuroendocrine tumors (NETs) showed the clinical role of new targeted agents and their impact on tumor response and outcome of whose patients affected by advanced NET. In this study, we summarize the available clinical data related to clinical efficacy of targeted therapies in the treatment of advanced NETs. METHODS: A meta-analysis of randomized studies in accordance with the PRISMA guidelines was performed after searching the databases of PubMed, the Cochrane Library, and the ASCO University Meeting for relevant publications. RESULTS: One thousand 9 hundred and 8 cases were included in the meta-analysis; among these, 1012 were in the experimental arm and 896 were in the control arm. The pooled analysis of the use of target agents in NETs revealed significantly increased of progression free survival compared to control group (hazard ratio = 0.59, 95% CI:0.42-0.84; P = 0.003). Subgroup analysis of patients according to tumor site showed a difference in favor of pancreatic neuroendocrine tumors. Moreover, targeted therapies improved the overall survival (hazard ratio = 0.79, 95%CI: 0.63-0.98; P = 0.03), and response rate (hazard ratio = 3.33, 95% CI 2.02-5.49; P < 0.00001) in all types of NETs. CONCLUSION: Our analysis supports the routine use of targeted agents for treatment of neuroendocrine tumors with particular regards to the pancreatic neuroendocrine tumorspartially_openembargoed_20171001Roviello, Giandomenico; Zanotti, Laura; Venturini, Sergio; Bottini, Alberto; Generali, DanieleRoviello, Giandomenico; Zanotti, Laura; Venturini, Sergio; Bottini, Alberto; Generali, Daniel

interface roughness parameters and shear strength

The interlayer bond strength between binder and wearing course and several possible treatments of enhancing the contact surface roughness and the interlocking are investigated. For this purpose, conventional methods, such as shear tests, but also laser image acquisition of the binder upper surface have been used. The mechanical outcomes of a shear test device and the binder surface roughness parameters, have been compared looking for a relation between the shear performance and the surface characteristics. The comparison between the roughness average and the root mean square of the profile heights with the maximum shear stress shows the achievement of the same strength level for treatments with similar roughness parameters, as proved by the statistical analysis. Furthermore, the comparison between the roughness parameter kurtosis and the maximum height of the profile with the slope of the response curve before the peak and residual shear stress, demonstrates a better locking for more high peaks

Mortuary behavior of the hunter gatherers from Médano Petroquímica site (La Pampa, Argentina). Preliminary characterization from a taphonomic approach

En este trabajo se propone la utilización de herramientas provenientes de la tafonomía y la arqueotanatología para ampliar el conocimiento sobre las costumbres mortuorias y los procesos de formación de sitio a partir del análisis de restos óseos humanos. La muestra proviene del sitio Médano Petroquímica, un área de inhumación ubicada al sudoeste de la provincia de La Pampa, Argentina, que habría sido originada por sociedades cazadoras recolectoras de finales del Holoceno Tardío. Los resultados obtenidos del estudio de cuatro entierros, uno primario y tres secundarios (NMI=19), sugieren que las huellas de corte y la permanencia de relaciones articulares son consistentes con prácticas de manipulación del cuerpo en diferentes momentos después de la muerte. Por su parte, la actividad de insectos se registró en mayor frecuencia en el entierro primario. Los fechados, junto con la presencia de insectos, ocre y las características específicas de cada rasgo soportarían mayormente la sincronía en la inhumación de los rasgos del sitio.This paper proposes the use of analytical tools from taphonomy and archaeothanatology to expand knowledge about mortuary customs and site formation processes from the analysis of human bone remains. The sample comes from the Médano Petroquímica site, an inhumation area located south west of La Pampa province, Argentina, which would have been originated by hunter-gatherer societies from the Late Holocene. The results obtained from the study of four burials, one primary and three secondary (NMI=19), suggest that the cut-marks and the presence of articular relationships are consistent with practices of body manipulation at different times after death. Furthermore, a greater frequency of insects activity was recorded in the primary burial. The radiocarbon dates, along with the presence of insects, ocher, and the specific features of each burial, would largely support the synchrony in the inhumation of the features of the site.Fil: Bottini, Melina Cecilia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Arrieta, Mario Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Bernardi, Lila. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin

Population structure and dynamic of hunter-gatherers from the médano petroquímica site (La Pampa, Argentina): Inferences from life tables and other paleodemographic indicators

La paleodemografía constituye una línea de investigación muchas veces subestimada en los estudios bioarqueológicos debido a que generalmente los sitios prehistóricos carecen de registros escritos que proporcionen información precisa de las sociedades que los generaron. Dado el importante número de individuos inhumados en el sitio Médano Petroquímica (n=120) y el breve periodo de ocupación del mismo (entre 363 y 419 años AP), la utilización de herramientas como las tablas de vida y de distintos índices paleodemográficos nos permitirá aportar información relevante de la dinámica poblacional para el área de estudio durante el Holoceno Tardío. Las tasas de mortalidad infantil y de fecundidad femenina, junto a otros indicadores, sugieren que se trataría de una población con tendencia hacia el crecimiento. Además, el análisis e interpretación de los resultados obtenidos apoyaría el cuadro propuesto por algunos investigadores, en el cual las sociedades de la región habrían experimentado una disminución de la movilidad residencial, el aumento de la densidad poblacional y la aparición de áreas formales de entierro durante el periodo de contacto hispano-indígena inicial.Paleodemography is a line of research that is often underestimated in bioarchaeological studies because prehistoric sites generally lack written records that provide accurate information about the societies that generated them. Given the high number of individuals buried at the Médano Petroquímica site and the short period of occupation thereof, the use of life tables and different paleodemographic indices would allow us to provide relevant information about population dynamics for the study area during the late Holocene. Infant mortality, female fertility rates, and other indicators suggest it would be a population with a tendency towards growth. In addition, the results would support the model proposed by some researchers of decreasing residential mobility in the region, increasing population density, and the appearance of formal burial areas during the initial period of Spanishindigenous contact.Fil: Bernardi, Lila. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arrieta, Mario Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; ArgentinaFil: Bottini, Melina Cecilia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Taphonomy in human skeletal remains from southwest pampean region: the Médano Petroquímica site (Puelén, La Pampa, Argentina)

El análisis tafonómico permite conocer el origen y las posibles causas de la preservación diferencial en restos óseos. Este conocimiento resulta de suma utilidad para abordar análisis bioarqueológicos, ya que proporciona información clave sobre los procesos de formación del registro bioantropológico y de las condiciones ambientales del pasado. Este trabajo se centra en el estudio de los procesos y agentes post-depósitacionales de origen no antrópico que actuaron en el sitio Médano Petroquímica, un sitio con entierros prehispánicos (entre 419 ± 46 AP y 363 ± 45 AP) ubicado al sudoeste de la provincia de La Pampa, Argentina. Se realizaron análisis tafonómicos en restos óseos humanos correspondientes a 19 individuos recuperados de un entierro primario simple y tres entierros secundarios múltiples. Se contabilizaron 4179 especímenes correspondientes a 1829 elementos. Los resultados muestran que los entierros múltiples fueron afectados de manera similar por las distintas variables consideradas. Aunque la meteorización fue la variable registrada con mayor frecuencia, la acción de raíces habría sido la que mayormente afectó la integridad de los elementos. Esta experiencia pretende destacar la importancia del análisis tafonómico en los entierros humanos para obtener información acerca de la influencia del ambiente en el registro bioarqueológico.Taphonomic analysis allows knowing the origin and the possible causes of the differential preservation in bone remains. This knowledge is very useful for approaching bioarchaeological analyzes, as it provides key information on the processes of formation of the bioanthropological record and the environmental conditions of the past. This work focuses on the study of post-depositional processes and agents of non-anthropogenic origin that affected the Médano Petroquímica site, a pre-Hispanic hunter-gatherer cemetery (between 419 ± 46 BP and 363± 45 BP) located in the southwest of the province of La Pampa, Argentina. Taphonomic analyzes were performed on human skeletal remains corresponding to 19 individuals recovered from a single primary burial and three multiple secondary burials. 4179 specimens corresponding to 1829 elements were counted. The results show that multiple burials were similarly affected by the variables considered. Although weathering was the most frequently recorded variable, the action of roots would have had the greatest impact on the integrity of the elements. This experience aims to highlight the importance of taphonomic analysis in human burials to obtain information about the environmental influence on the bioarchaeological record.Fil: Bottini, Melina Cecilia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Arrieta, Mario Alberto. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Bernardi, Lila. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin