Strategies to Reduce Porosity in Al-Mg WAAM Parts and Their Impact on Mechanical Properties

Open AccessFeature PaperArticle Strategies to Reduce Porosity in Al-Mg WAAM Parts and Their Impact on Mechanical Properties by Maider Arana 1,2,* [OrcID] , Eneko Ukar 2, Iker Rodriguez 1, Amaia Iturrioz 1 [OrcID] and Pedro Alvarez 1 [OrcID] 1 LORTEK Technological Centre, Basque Research and Technology Alliance (BRTA), 20240 Ordizia, Spain 2 Mechanical Engineering Department, University of the Basque Country UPV/EHU, 48013 Bilbao, Spain * Author to whom correspondence should be addressed. Academic Editor: Eric Hug Metals 2021, 11(3), 524; https://doi.org/10.3390/met11030524 Received: 1 March 2021 / Revised: 16 March 2021 / Accepted: 18 March 2021 / Published: 23 March 2021 (This article belongs to the Special Issue Directed Energy Deposition of Metal Alloys) Download PDF Browse Figures Review Reports Citation Export Abstract With the advent of disruptive additive manufacturing (AM), there is an increasing interest and demand of high mechanical property aluminium parts built directly by these technologies. This has led to the need for continuous improvement of AM technologies and processes to obtain the best properties in aluminium samples and develop new alloys. This study has demonstrated that porosity can be reduced below 0.035% in area in Al-Mg samples manufactured by CMT-based WAAM with commercial filler metal wires by selecting the correct shielding gas, gas flow rate, and deposition strategy (hatching or circling). Three phase Ar+O2+N2O mixtures (Stargold®) are favourable when the hatching deposition strategy is applied leading to wall thickness around 6 mm. The application of circling strategy (torch movement with overlapped circles along the welding direction) enables the even build-up of layers with slightly thicker thickness (8 mm). In this case, Ar shielding gas can effectively reduce porosity if proper flow is provided through the torch. Reduced gas flows (lower than 30 Lmin) enhance porosity, especially in long tracks (longer than 90 mm) due to local heat accumulation. Surprisingly, rather high porosity levels (up to 2.86 area %) obtained in the worst conditions, had a reduced impact on the static tensile test mechanical properties, and yield stress over 110 MPa, tensile strength over 270 MPa, and elongation larger than 27% were achieved either for Ar circling, Ar hatching, or Stargold® hatching building conditions. In all cases anisotropy was lower than 11%, and this was reduced to 9% for the most appropriate shielding conditions. Current results show that due to the selected layer height and deposition parameters there was a complete re-melting of the previous layer and a thermal treatment on the prior bottom layer that refined the grain size removing the original dendritic and elongated structure. Under these conditions, the minimum reported anisotropy levels can be achieved.This research was supported by the Ministry of Science and innovation of the Spain Government through the program “Ayudas Destinadas a Centros Tecnológicos de Excelencia CERVERA Año 2019” from CDTI (Centro para el Desarrollo Tecnológico Industrial) in the frame of the CEFAM Project, grant CER-20191005

Divulgación de información sobre corrupción: empresas del IBEX 35: Corruption Reporting Disclosure: IBEX 35 Companies

Interest in the relationship between corruption and the private sector has increased in recent times. This paper aims to explore this issue with social effects from a double perspective: on one hand, knowing the reality of the disclosure of corruption in the IBEX 35 Spanish companies, and later try to analyze what are the underlying motivations for such practices and possible implications for internal management. To achieve this goal, initially conducted an exploratory analysis of information on corruption issued by the Ibex 35 companies in their sustainability reports and then –based on the Legitimacy Theory– conducted an in depth interview with a person responsible for CSR, in order to detect the motivations and implications in management. The conclusions reached are: firstly, the information on corruption provided by the companies can specify in three general aspects (anti-corruption policy, audit and control systems, and mechanisms of implementation). Secondly, we have identified three clusters in the companies, highlighting the company Telefonica because of it particular behaviour. Lastly, when analyzing the case of this company, we have seen how it intends to maintain a high level of legitimacy, for it attempts to comply with rules socially constructed, and used the disclosure to continue its status as a “legitimate business” and try to create value and confidence. However, the procedures relating to the management of corruption not seem to have reached the level of specificity that is currently required.El interés por la relación existente entre la corrupción y el sector privado se ha incrementado en los últimos tiempos. El presente trabajo pretende estudiar este asunto con efectos sociales desde una doble perspectiva; por una parte, conocer la realidad actual de la divulgación sobre corrupción en las empresas españolas del Ibex 35 para, posteriormente, tratar de analizar cuáles son las motivaciones subyacentes de tales prácticas y las posibles implicaciones en la gestión interna. Para alcanzar este objetivo, inicialmente realizamos un análisis exploratorio de la información relativa a la corrupción emitida por las empresas del Ibex 35 en sus memorias de sostenibilidad y, posteriormente, –basándonos en la Teoría de la Legitimidad– realizamos una entrevista en profundidad con un ejecutivo responsable de la RSC, con el objetivo de detectar las motivaciones y las implicaciones en la gestión. Las conclusiones alcanzadas son: en primer lugar, la información sobre corrupción aportada por las empresas se puede concretar en tres aspectos generales (política contra la corrupción, auditorías y sistemas de control, y los mecanismos de implementación). En segundo lugar, hemos identificado tres clusters en las empresas, destacando en este agrupamiento por su particular comportamiento, la compañía Telefónica. Por último, al analizar el caso de esta compañía, hemos observado cómo pretende mantener un nivel alto de legitimidad; para ello, intenta cumplir con las normas socialmente establecidas, y emplea la divulgación para continuar con su estatus de “empresa legítima”, e intenta generar valor y confianza. Sin embargo, los procedimientos en relación a la gestión de la corrupción parecen no haber alcanzado el nivel de concreción que en la actualidad se les exige

Sex differences in the aging pattern of renin–angiotensin system serum peptidases

Background: Serum peptidases, such as angiotensin-converting enzyme (ACE), angiotensin-converting enzyme-2 (ACE2), neutral endopeptidase (NEP), aminopeptidase N (APN), and aminopeptidase A (APA), are important elements of the renin-angiotensin system (RAS). Dysregulation of these enzymes has been associated with hypertension and cardiovascular risk. In the present study, serum activities of RAS peptidases were analyzed to evaluate the existence of sexual differences, with a possible different pattern in pre- and post-andropausal/post-menopausal participants. Methods: One hundred and eighteen healthy men and women between 41 and 70 years of age (58 women and 60 men) were recruited to participate in the study. Serum RAS-regulating enzymes were measured by spectrofluorimetry. Enzymatic activity was recorded as units of enzyme per milliliter of serum (U/mL). Results: Significantly lower serum APA activity was observed in men with respect to women; no sex differences were detected for ACE, ACE2, NEP, or APN. Significantly lower APA and ACE serum activity were observed in older men compared to older women. In contrast, younger (<55 years) men had significantly higher values of NEP serum activity than younger women. Significantly lower ACE serum activity was detected in older men compared to younger men. In women, significantly higher ACE2 serum activity was observed in older women compared to younger women. Conclusions: These results suggest a differential effect of aging on the activity of RAS enzymes in men and women, especially with respect to the breakpoint of andropausia/menopausia, on the critical serum enzymatic activities of the RAS, which could correlate with sexual differences in cardiovascular risk.This work was supported by a grant from the Basque Government (IT8-11/13), the University of the Basque Country UPV/EHU (UFI 11/44), and the Gangoiti-Barrera Foundation

Obesity Parameters, Physical Activity, And Physical Fitness are Correlated With Serum Dipeptidyl Peptidase IV Activity In A Healthy Population

Objective: To determine whether obesity, physical fitness, and physical activity parameters are associated with the enzymatic activity of serum dipeptidyl peptidase IV (sDPPIV) in a sample of healthy women and men. Design and methods: We have correlated parameters of obesity, physical fitness, and physical activity with sDPPIV activity in 374 healthy subjects (age: 60.7 +/- 6.9 years, body mass index: 26.1 +/- 4.1 kg/m(2)). Enzymatic activity was analyzed using spectrofluorimetry, body composition was assessed by impedanciometry, physical fitness data were obtained using the Senior Fitness Test, and physical activity data were collected by accelerometer. Pearson' s partial correlation analysis was applied to determine the relationship between DPPIV activity and the rest of parameters and significantly correlated variables were introduced into linear regression models to predict DPPIV. Results: Serum DPPIV activity was negatively associated with obesity parameters such as body mass (r = -0.112), body mass index (BMI) (r = -0.147), waist circumference (r = -0.164), waist-to-hip ratio (-0.104), and percentage of fat mass (r = -0.185). Serum DPPIV activity was positively associated with cardiovascular fitness (r = 0.138), total amount of physical activity (r = 0.153), and time spent doing light exercise (r = 0.184). Regression models revealed sex differences in enzyme activity with overall activity higher in women than in men (beta = 0.437, p < 0.001). Further, percent fat mass was an independent negative predictor of DPPIV activity (beta = -0.184, p = 0.001). Serum DPPIV activity was positively predicted based on the amount of time spent doing light physical activity (beta = 0.167, p = 0.001). Conclusion: Our results demonstrate that sDPPIV activity is positively associated with healthier parameters regarding fatness, fitness and physical activity.This work was supported by the Basque Government (GIC12/173: IT811-13) and the University of the Basque Country (UPV/EHU: PPG17/40)

Intramolecular trimerization, a novel strategy for making multispecific antibodies with controlled orientation of the antigen binding domains

Here, we describe a new strategy that allows the rapid and efficient engineering of mono and multispecific trivalent antibodies. By fusing single-domain antibodies from camelid heavy-chain-only immunoglobulins (VHHs) to the N-terminus of a human collagen XVIII trimerization domain (TIEXVIII) we produced monospecific trimerbodies that were efficiently secreted as soluble functional proteins by mammalian cells. The purified VHH-TIEXVIII trimerbodies were trimeric in solution and exhibited excellent antigen binding capacity. Furthermore, by connecting with two additional glycine-serine-based linkers three VHH-TIEXVIII modules on a single polypeptide chain, we present an approach for the rational design of multispecific tandem trimerbodies with defined stoichiometry and controlled orientation. Using this technology we report here the construction and characterization of a tandem VHH-based trimerbody capable of simultaneously binding to three different antigens: carcinoembryonic antigen (CEA), epidermal growth factor receptor (EGFR) and green fluorescence protein (GFP). Multispecific tandem VHH-based trimerbodies were well expressed in mammalian cells, had good biophysical properties and were capable of simultaneously binding their targeted antigens. Importantly, these antibodies were very effective in inhibiting the proliferation of human epidermoid carcinoma A431 cells. Multispecific VHH-based trimerbodies are therefore ideal candidates for future applications in various therapeutic areas.FJB was supported by a grant from the Ministerio de Economía y Competitividad (CTQ2014-56966-R). JB and BO were supported by a grant from the Ministerio de Economía y Competitividad (BIO2011-22568). AA-C and AB-T were supported by Programa Torres Quevedo from Ministerio de Economía y Competitividad, cofounded by the European Social Fund (PTQ09-01-01089 and PTQ11–04604, respectively). SLH is a recipient of the 2016 Novo Scholarship