Definition and Analysis of Uncertainty Contributors in the Dimensional Measurement of Bronze Sintered Samples

The paper concerns the definition and estimation of uncertainty elements. This topic is matched with Direct Metal Selective Laser Sintering used for manufacturing the samples. The UNI ENV ISO 14253-2: 2003 standard deals with uncertainty sources in dimensional measurement. This paper treats just those ones regarding measurement procedure, measurement equipment and workpiece. The aim of this paper is estimating combined standard uncertainty. Measurement repeatability, workpiece fixing and number of points for the definition of geometric elements arise from measurement procedure. Measurement equipment uncertainty is connected with Maximum Permissible Error. As far as workpiece uncertainty components, surface roughness, form error and temperature are checked

Helicobacter pylori and pregnancy-related disorders.

Helicobacter pylori (H. pylori) infection is investigated in gastric diseases even during pregnancy. In particular, this Gram-negative bacterium seems to be associated with hyperemesis gravidarum, a severe form of nausea and vomiting during pregnancy. During the last decade, the relationship among H. pylori and several extra-gastric diseases strongly emerged in literature. The correlation among H. pylori infection and pregnancy-related disorders was mainly focused on iron deficiency anemia, thrombocytopenia, fetal malformations, miscarriage, pre-eclampsia and fetal growth restriction. H. pylori infection may have a role in the pathogenesis of various pregnancy-related disorders through different mechanisms: depletion of micronutrients (iron and vitamin B(12)) in maternal anemia and fetal neural tube defects; local or systemic induction of pro-inflammatory cytokines release and oxidative stress in gastrointestinal disorders and pre-eclampsia; cross-reaction between specific anti-H. pylori antibodies and antigens localized in placental tissue and endothelial cells (pre-eclampsia, fetal growth restriction, miscarriage). Since H. pylori infection is most likely acquired before pregnancy, it is widely believed that hormonal and immunological changes occurring during pregnancy could activate latent H. pylori with a negative impact not only on maternal health (nutritional deficiency, organ injury, death), but also on the fetus (insufficient growth, malformation, death) and sometime consequences can be observed later in life. Another important issue addressed by investigators was to determine whether it is possible to transmit H. pylori infection from mother to child and whether maternal anti-H. pylori antibodies could prevent infant’s infection. Studies on novel diagnostic and therapeutic methods for H. pylori are no less important, since these are particularly sensitive topics in pregnancy conditions. It could be interesting to study the possible correlation between H. pylori infection and other pregnancy-related diseases of unknown etiology, such as gestational diabetes mellitus, obstetric cholestasis and spontaneous preterm delivery. Since H. pylori infection is treatable, the demonstration of its causative role in pregnancy-related disorders will have important social-economic implications

Dimensional Analysis in Selective Laser Melting

This paper aims to use dimensional analysis technique for evaluating the properties of laser sintered components manufactured with Selective Laser Melting (SLM) process from metallic powders. The complexity of SLM does not allow to define an exhaustive mathematical model which involves all governing parameters and, therefore, the dimensional analysis might be a powerful tool for the expression of output parameters as function of dimensionless numbers appropriately defined from the input parameters set. As an example of the developed procedure, the paper explains the construction of a response function for the expression of relative density

Porosity evolution in aluminum alloy 2024 bop and butt defocused welding by Yb-YAG disk laser

In many industrial applications, in order to obtain good results in laser welding processes, it may not be sufficient to use a focused beam on the upper surface, so a defocused beam is required instead. This study aims to investigate which advantages a defocused beam may offer in welding aluminum alloy 2024 using Yb:YAG disk laser. A characterization of laser beam geometry is preliminary necessary, in order to correlate bead features and effective specific energy provided. Porosity content decrease and enhanced penetration depth have been obtained with defocused beam; welding behavior has been related to magnesium loss via EDS analysis. Considering the shape of the cross sections of the bead in butt welding, the relation between key-hole instability and porosity formation has also been discussed. For the alloy in exam, the welding range to perform structurally sound and defect-free welds is found to be tight

Investigation on edge joints of Inconel 625 sheets processed with laser welding

Abstract Laser welding of Inconel 625 edge joint beads in square groove configuration was investigated. The use of different weld geometries in new aerospace solutions explains research on edge joints. A structured plan was carried out in order to characterize the process defining the influence of laser power and welding speed and to study possible interactions among the governing factors. As weld pool protection is crucial in order to obtain sound joints when processing superalloys, a special glove box for gas supply was designed to upgrade the welding head. Welded joints were characterized referring to bead profile, microstructure and X-rays. It was found that heat input plays an important role as it affects welding stability, porosity content and bead shape. Results suggest operating with low values of heat input to reduce porosity and guarantee stable bead conformation. Furthermore, a decrease in the grain size has been observed as a consequence of decreasing heat input

Helicobacter pylori’s Virulence and Infection Persistence Define Preeclampsia complicated by Fetal Growth Retardation.

AIM: To better understand the pathogenic role of Helicobacter pylori (H. pylori) in pre-eclampsia (PE), and whether it is associated or not with fetal growth retardation (FGR). METHODS: Maternal blood samples were collected from 62 consecutive pregnant women with a diagnosis of PE and/or FGR, and from 49 women with uneventful pregnancies (controls). Serum samples were evaluated by immunoblot assay for presence of specific antibodies against H. pylori antigens [virulence: cytotoxin-associated antigen A (CagA); ureases; heat shock protein B; flagellin A; persistence: vacuolating cytotoxin A (VacA)]. Maternal complete blood count and liver enzymes levels were assessed at delivery by an automated analyzer. RESULTS: A significantly higher percentage of H. pylori seropositive women were found among PE cases (85.7%) compared to controls (42.9%, P < 0.001). There were no differences between pregnancies complicated by FGR without maternal hypertension (46.2%) and controls. Importantly, persistent and virulent infections (VacA/CagA seropositive patients, intermediate leukocyte blood count and aspartate aminotransferase levels) were exclusively associated with pre-eclampsia complicated by FGR, while virulent but acute infections (CagA positive/VacA negative patients, highest leukocyte blood count and aspartate aminotransferase levels) specifically correlated with PE without FGR. CONCLUSION: Our data strongly indicate that persistent and virulent H. pylori infections cause or contribute to PE complicated by FGR, but not to PE without feto-placental compromise

Manufacturing and characterization of similar to foam steel components processed through selective laser melting

The growing interest from the industry for lightweight metal components has driven the development of processes that would allow creating lightweight high melting point metals as steels, able to guarantee mechanical characteristics superior to existing foam (typically aluminium), without penalizing one of the characteristics that cell structures have: lightness. Conventional manufacturing methods, such as casting, however, face difficulty in making complex periodic steel structures with designed shape and size and volume fraction. This study evaluates the manufacturability and performance of lightweight 17–4 PH steel components with spherical porosity fabricated via selective laser melting (SLM). Samples were designed and fabricated with the purpose to produce a structure similar to foam. Built samples were characterized in terms of dimensional accuracy, mechanical strength under compression and energy absorbed per unit mass. The designed structures have a designed relative density or volume fraction ranging between 31.1 and 32.8%

Role of the macrophage migration inhibitory factor in the pathophysiology of pre-eclampsia

Proinflammatory cytokines are produced in pregnancy in response to the invading pathogens and/or nonmicrobial causes such as damage-associated molecules and embryonic semi-allogenic antigens. While inflammation is essential for a successful pregnancy, an excessive inflammatory response is implicated in several pathologies including pre-eclampsia (PE). This review focuses on the proinflammatory cytokine macrophage migration inhibitory factor (MIF), a critical regulator of the innate immune response and a major player of processes allowing normal placental development. PE is a severe pregnancy-related syndrome characterized by exaggerated inflammatory response and generalized endothelial damage. In some cases, usually of early onset, it originates from a maldevelopment of the placenta, and is associated with intrauterine growth restriction (IUGR) (placental PE). In other cases, usually of late onset, pre-pregnancy maternal diseases represent risk factors for the development of the disease (maternal PE). Available data suggest that low MIF production in early pregnancy could contribute to the abnormal placentation. The resulting placental hypoxia in later pregnancy could produce high release of MIF in maternal serum typical of placental PE. More studies are needed to understand the role of MIF, if any, in maternal PE