Process Parameters Development of Selective Laser Melting of Lunar Regolith for On‐Site Manufacturing Applications

Selective Laser Melting (SLM) is a candidate for on‐site manufacturing as its characteristics of energy source and powder‐based fabrication process are suitable for use with in situ material. The feasibility of using lunar regolith simulant to create objects with SLM process is investigated in this study. The process parameters are optimized and multiple objects are fabricated. A qualitative chemical analysis is carried out with scanning electron microscopy using energy‐dispersive X‐ray emission. Lastly, properties such as particle size distribution, particle shape, and crystal structure of the lunar simulant powder as well as the crystallinity and hardness of the fabricated objects are investigated.     

Selenomethionine increases proliferation and reduces apoptosis in bovine mammary epithelial cells under oxidative stress

The decline in mammary epithelial cell number as lactation progresses may be due, in part, to oxidative stress. Selenium is an integral component of several antioxidant enzymes. The present study was conducted to examine the effect of oxidative stress and selenomethionine (SeMet) on morphology, viability, apoptosis, and proliferation of bovine mammary epithelial cells (BMEC) in primary culture. Cells were isolated from mammary glands of lactating dairy cows and grown for 3 d in a low-serum gel system containing lactogenic hormones and 0 or 100 μM H₂O₂ with 0, 10, 20, or 50 nM SeMet. Hydrogen peroxide stress increased intracellular H₂O₂ to 3 times control concentrations and induced a loss of cuboidal morphology, cell-cell contact, and viability of BMEC by 25%. Apoptotic cell number more than doubled during oxidative stress, but proliferating cell number was not affected. Supplementation with SeMet increased glutathione peroxidase activity 2-fold and restored intracellular H₂O₂ to control levels with a concomitant return of morphology and viability to normal. Apoptotic BMEC number was decreased 76% below control levels by SeMet and proliferating cell number was increased 4.2-fold. These findings suggest that SeMet modulated apoptosis and proliferation independently of a selenoprotein-mediated reduction of H₂O₂. In conclusion, SeMet supplementation protects BMEC from H₂O₂-induced apoptosis and increased proliferation and cell viability under conditions of oxidative stress.     

Determination of Ca,Cd, Cu,Fe, K,Mg, Mn,Mo, Na,Se, and Zn in Foodstuffs by Atomic Spectrometry After Sample Preparation Using a Low-Cost Closed-Vessel Conductively Heated Digestion System

Establishing fast, simple, low-cost, and efficient sample preparation procedures to determine elements in foodstuffs is a relevant aspect for nutritional and health purposes. For this reason, the recently proposed closed-vessel conductively heated digestion system (CHDS) was evaluated for the digestion of milk powder, chocolate powder, and soluble coffee samples aiming for Ca, Cu, Fe, K, Mg, Mn, Na, and Zn determinations by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) and Cd, Mo, and Se determinations by inductively coupled plasma mass spectrometry with tandem configuration (ICP-MS/MS). The accuracy was evaluated by analyzing two milk certified reference materials digested by the CHDS and a microwave oven for comparison. When using the CHDS, recoveries for the analytes varied from 91 to 104 %. For microwave digestions, recoveries within the 94–109 % intervals were obtained. The method was then applied to the samples. For comparative purposes, the analytes were also determined in the samples after microwave digestion, and the results between the two digestion systems showed no differences based on a paired t test at a 95 % confidence level. Similar analytical blanks were obtained because quartz digestion tubes were used in both digestion systems. The CHDS with quartz tubes is an interesting alternative for laboratories dedicated to large-scale routine analysis because volatile elements usually found in very low concentrations in food samples such as Cd and Se can also be determined.     

Quality Enhancement of Chilled Fish by Including Alga <Emphasis Type="Italic">Bifurcaria bifurcata</Emphasis> Extract in the Icing Medium

Bifurcaria bifurcata is a widely extended brown macroalga, whose antimicrobial and antioxidant properties have previously been described. In this study, ethanolic extracts of B. bifurcata were included in the icing medium employed for the chilled storage of megrim (Lepidorhombus whiffiagonis). For it, two different concentrations of this brown macroalga extract (0.67 and 2.50 g lyophilized alga L^?1 aqueous solution; B-1 and B-2 batches, respectively) were tested for a 14-day storage. The effect of the alga extract was compared with a counterpart batch stored in traditional ice prepared only from water (B-0 batch). Significant (p < 0.05) inhibitions of microbial activity (aerobes, psychrotrophs, lipolytic bacteria, proteolytic bacteria and Enterobacteriaceae) as well as of pH and trimethylamine formation were observed as a result of the incorporation of the alga extract in the icing medium, being this effect especially relevant in the B-2 batch. Concerning lipid damage development, a significantly (p < 0.05) lower formation of free fatty acids (lipid hydrolysis development) and of fluorescent compounds (tertiary lipid oxidation development) in samples corresponding to both alga-including batches could also be observed; this inhibitory effect was more intense in fish belonging to the B-2 batch. The icing medium proposed in this work constitutes a promising strategy in order to apply algae extracts to enhance fish quality retention during the different steps of storage and commercialization of marine species.     

Karhunen-Loeve decomposition in the presence of symmetry. I

The Karhunen-Loeve (KL) decomposition is widely used for data which very often exhibit some symmetry, afforded by a group action. For a finite group, we derive an algorithm using group representation theory to reduce the cost of determining the KL basis. We demonstrate the technique on a Lorenz-type ODE system. For a compact group such as tori or SO(3,R) the method also applies, and we extend results to these cases. As a short example, we consider the circle group S(1 ).     

Remote detection of a tonal anomaly in an area of hydrocarbon microseepage,Tucano basin,north-eastern Brazil

Mapping of a tonal anomaly in an area of hydrocarbon microseepage was possible using a Landsat-Thematic Mapper false-colour composite consisting of TM2/3, TM4/3 and of the difference TM2/3-TM4/3, displayed as red, green and blue, respectively. In this false-colour composite, green and yellow express variations in the vegetation cover, whereas hues of magenta are related to terrain conditions representing bleached materials, which occur close to the centre of a soil gas anomaly. Simultaneous occurrence of anomalous soil gas values with magnetic and radioactive minerals suggests that a reducing environment associated with the microseepage phenomenon created the bleached materials, identified as a tonal anomaly in the enhanced TM image.     

Biased TCR repertoire in infiltrating lesional T cells in human Bancroftian filariasis

To investigate the hypothesis that T cells recognizing specific Ags localize to the site of disease activity in human bancroftian filariasis, we have compared the repertoire of TCR Vbeta gene segments in lesions vs blood in individual patients by RT-PCR ELISA. Vbeta14 and Vbeta24 were overrepresented (5% greater in tissue compared with PBMCs and/or tissue/PBMC ratios in the highest 5% of all tissue/PBMC ratios for all Vbetas for all subjects) in 50% and 40% of study subjects, respectively. Overrepresentation of these two Vbetas did not occur in any control subject. In comparing three patient groups, the proportion of individuals meeting at least one criterion for Vbeta14 overrepresentation was shown to increase in tandem with our current concepts of disease progression (asymptomatic filariasis = 25%; clinical filariasis with active infection = 60%; clinical filariasis without active infection = 71%). In 6 of the 10 individuals with Vbeta14 overrepresentation, Vbeta14 represented >20% of the entire lesional Vbeta repertoire. All but one of the 20 study subjects had at least one Vbeta gene segment that was overrepresented in tissue compared with PBMCs. Only a small number of Vbetas, usually three or less, were overrepresented in any single filariasis patient. However, in the same tissue, no differences between patient groups were found when IFN-gamma, TNF-alpha, IL-4, IL-5, and IL-12 mRNA expression were examined. Taken together, these findings suggest that, in principle, in essentially all patients, whether with subclinical or with clinical filariasis, distinct and limited T cell populations are concentrated in affected tissue.     

Numerical Methods to Simulate and Visualize Detailed Crane Activities

Abstract:   Virtual construction allows engineers to simulate and visualize construction progress on computer before commencing the real project and is becoming an important technique to manage fast-track and complicated construction projects. One major consideration for virtual construction is the simulation of the operation of construction equipment for a construction project. This research specifically focuses on developing a mathematical model to support the simulation and visualization of cranes, the most critical equipment in terms of project controls. This model is composed of two submodels—a kinematics model and a dynamic model. The kinematics model is to present the crane components controlled by the operators. The dynamic model is to present the dynamic behavior in suspended system (including the cable and rigging object), which cannot be controlled directly by the operators. To verify the feasibility of these methods, a computer program that simulates and visualizes detailed crane activities was developed. This program supports the real-time visualization of crane activities with high degree of reality accuracy and also, enables the detailed simulation of long-term construction projects .     

A new approach to analyze the degradation and breakdown of thin SiO2 films under static and dynamic electrical stress

A test procedure, which provokes the oxide breakdown in two stages, is proposed to analyze the degradation and breakdown of thin SiO ₂ films. This procedure can partially overcome the problems associated with dynamic tests and allows a direct comparison of static and dynamic stresses. The analysis of the data obtained using the proposed method has allowed us to conclude that the oxide breakdown is strongly affected by the degradation induced at the beginning of the test. This result provides a high sensibility to the method, helping it to study the oxide degradation under tests closer to operation conditions keeping reasonable testing times     

Development of a magnetic sensor for detection and sizing of internal pipeline corrosion defects

Magnetic flux leakage (MFL) is the most used technique for pipeline inspection, being applied through the use of instrumented PIGs. The pipe wall is magnetized and when metal loss or other irregularities occur, a larger fraction of the magnetic flux “leaks” outwards from the wall and is detected by sensors. MFL presents some limitations since it requires magnetic saturation of the pipe wall. Therefore, it is difficult to inspect small diameter and thick wall pipelines. Internal corrosion sensor (ICS) has been developed as a solution for internal corrosion measurements of thick walls. The technique, also called “field disturbance”, is based in a direct magnetic response from a small area of the wall. It is not necessary to achieve the magnetic saturation of the pipe material, and thus ICS performance is not affected by the thickness of the pipe wall. In the present work, finite element calculations are performed and the best resultant configuration of the sensor is proposed. Experimental tests with a prototype were carried out and the results give a strong indication of the validity of the theoretical model proposed for sizing.