On the Interface Between LENS® Deposited Stainless Steel 304L Repair Geometry and Cast or Machined Components

Laser Engineered Net Shaping™ (LENS®) is being evaluated for use as a metal component repair/modification process. A component of the evaluation is to better understand the characteristics of the interface between LENS deposited material and the substrate on which it is deposited. A processing and metallurgical evaluation was made on LENS processed material fabricated for component qualification tests. A process parameter evaluation was used to determine optimum build parameters and these parameters were used in the fabrication of tensile test specimens to study the characteristics of the interface between LENS deposited material and several types of substrates. Analyses of the interface included mechanical properties, microstructure, and metallurgical integrity. Test samples were determined for a variety of geometric configurations associated with interfaces between LENS deposited material and both wrought base material or previously deposited LENS material. Thirteen different interface configurations were fabricated for evaluation representing a spectrum of deposition conditions from complete part build, to hybrid substrate-LENS builds, to repair builds for damaged or re-designed housings. Good mechanical properties and full density were observed for all configurations. When tested to failure, fracture occurred by ductile microvoid coalescence. The repair and hybrid interfaces showed the same metallurgical integrity as, and had properties similar to, monolithic LENS deposits.Mechanical Engineerin

Thermal Behavior in the Lens Process

Direct laser metal deposition processing is a promising manufacturing technology which could significantly impact the length oftime between initial concept and finished part. For adoption ofthis technology in the manufacturing environment, further understanding is required to ensure robust components with appropriate properties are routinelyfabricated. This requires a complete understanding ofthe thermal history.during part fabrication and control ofthis behavior. This paper will describe our research to understand the thermal behavior for the Laser Engineered Net Shaping (LENS) process!, where a component is fabricated by focusing a laser beam onto a substrate to create a molten pool in which powder particles are simultaneously injected to build each layer. The substrate is moved beneath the l~ser beam to deposit a thin cross section, thereby creating the desired geometry for each layer. After deposition of each layer, the powder delivery nozzle and focusing lens assembly is incremented in the positive Z-direction, thereby building a three dimensional component layer additively. It is important to control the thermal behavior to reproducibly fabricate parts. The ultimate intent is to monitor the thermal signatures and to incorporate sensors and feedback algorithms to control part fabrication. With appropriate control, the geometric properties (accuracy, surface finish, low warpage) as well as the materials' properties (e.g. strength, ductility) of a component can be dialed into the part through the fabrication parameters. Thermal monitoring techniques will be described, and their particular benefits highlighted. Preliminary details in correlating thermal behavior with processing results will be discussed.Mechanical Engineerin

Population genetic data for 17 Y STR markers from Benghazi (East Libya)

The seventeen Y-STR loci included in the AmpF‘STR1 YfilerTM PCR Amplification kit (DYS19, DYS389I,DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385a/b, DYS438, DYS439, DYS437, DYS448, DYS458,DYS456, DYS635, and Y-GATA-H4) were used to type a sample population of 238 males from eastern Libya (Benghazi region). Of 238 observed haplotypes, 214 were unique (90%) and 24 (10%) were found more than once. The 17 loci gave a discriminating power of 0.999. DYS458 showed the highest diversity as a single-locus marker (0.73). Allelic frequencies and gene diversities for each Y-STR locus were determined. The high haplotype diversity and discrimination capacity (0.996) demonstrate the utility of these loci for human identification in forensic applications. Comparative analysis with Y-STR datasets of relevant populations and submission of the haplotypes to the Y-STR Haplotype Reference Database (YHRD) was undertaken

TAS2R38 bitter taste genotype is associated with complementary feeding behavior in infants

Background: Genetically mediated sensitivity to bitter taste has been associated with food preferences and eating behavior in adults and children. The aim of this study was to assess the association between TAS2R38 bitter taste genotype and the first complementary food acceptance in infants. Parents of healthy, breastfed, term-born infants were instructed, at discharge from the nursery, to feed their baby with a first complementary meal of 150 mL at 4 to 6 months of age. They recorded the day when the child ate the whole meal in a questionnaire. Additional data included food composition, breastfeeding duration, feeding practices, and growth at 6 months. Infants' TAS2R38 genotypes were determined at birth, and infants were classified as "bitter-insensitive" (genotype AVI/AVI) and "bitter-sensitive" (genotypes AVI/PAV or PAV/PAV). Results: One hundred seventy-six infants and their mothers were enrolled; completed data were available for 131/176 (74.4%) infants (gestational age 39.3 \ub1 1.1 weeks, birth weight 3390 \ub1 430 g). Bitter-insensitive were 45/131 (34.3%), and bitter-sensitive were 86/131 (65.6%). Thirty-one percent of bitter-insensitive infants consumed the whole complementary meal at first attempt, versus 13% of bitter-sensitive ones (p = 0.006). This difference was significant independently of confounding variables such as sex, breastfeeding, or foods used in the meal. Growth at 6 months did not differ between the two groups. Conclusions: Differences in TAS2R38 bitter taste gene were associated with acceptance of the first complementary food in infants, suggesting a possible involvement in eating behavior at weaning

Experimental and numerical study of strength mismatch in cross-weld tensile testing

The mechanical properties of welded boiler tubes used in power plants can be significantly altered as a result of the fabrication history, such as pre-straining and heat treatment. The primary aim of the study was to determine the effect of fabrication history on local tensile properties across the welds. This was achieved by testing cross-weld specimens machined from welded thin-walled tubes (with unstrained or pre-strained base metal) before and after heat treatment. Digital image correlation, which is a full-field strain measurement technique, was implemented in order to obtain the local stress–strain curves and to extract the corresponding local tensile properties such as offset proof stress. Evidence of strain hardening due to the constraint and thermo-mechanical cycles during the welding process was found in the heat-affected zone and evidence of softening was observed in the pre-strained base metal. It was found that the heat treatment process removed the effect of pre-straining and welding on the proof stress and the strength along the specimen was nearly homogenized. However, mapping the local stress–strain curves in the as-welded cross-weld specimens with pre-strained base metal has revealed abnormal strain relaxation with increase in load in the weld-affected region. For a better understanding of this behaviour, a tensile test of a cross-weld specimen with a large strength mismatch between the weld metal and the base metal was simulated using the finite element method. It was found that the strength mismatch in the specimen causes the development of biaxial stresses in the heat-affected zone once local yielding begins, and the use of global axial stress to construct the local stress–strain curve results in an apparent ‘reduced-strain’ anomaly. Nevertheless, for the strength mismatch ratios studied, this anomalous behaviour did not seem to significantly affect the determination of the local proof stress in the specimens

Detecting expert’s eye using a multiple-kernel Relevance Vector Machine

Decoding mental states from the pattern of neural activity or overt behavior is an intensely pursued goal. Here we applied machine learning to detect expertise from the oculomotor behavior of novice and expert billiard players during free viewing of a filmed billiard match with no specific task, and in a dynamic trajectory prediction task involving ad-hoc, occluded billiard shots. We have adopted a ground framework for feature space fusion and a Bayesian sparse classifier, namely, a Relevance Vector Machine. By testing different combinations of simple oculomotor features (gaze shifts amplitude and direction, and fixation duration), we could classify on an individual basis which group - novice or expert - the observers belonged to with an accuracy of 82% and 87%, respectively for the match and the shots. These results provide evidence that, at least in the particular domain of billiard sport, a signature of expertise is hidden in very basic aspects of oculomotor behavior, and that expertise can be detected at the individual level both with ad-hoc testing conditions and under naturalistic conditions - and suitable data mining. Our procedure paves the way for the development of a test for the \u201cexpert\u2019s eye\u201d, and promotes the use of eye movements as an additional signal source in Brain-Computer-Interface (BCI) systems

Analysis of the antibiotic resistance profiles in methicillin-sensitive s. Aureus pathotypes isolated on a commercial rabbit farm in Italy

The breeding of meat rabbits is an important sector in the livestock industry in Italy. The focus of this study was to describe the antibiotic resistance profile distribution among the Methicillin-sensitive Staphylococcus aureus isolated in a rabbit farm. From 400 animals of different ages and three farm workers, 96 randomly selected strains isolated from various anatomical sites and lesions were analysed. According to spa typing and the resistance profiles towards veterinary and human antibiotics, 26 pathotypes were identified. The highest resistance was observed against Tetracyclines (92.3%) and Macrolides (80.8%), while almost all were susceptible to Penicillins, according to the limited use of β-lactams on the farm. In total, 92.3% of pathotypes were multidrug resistant (MDRs). Two MDR pathotypes belonging to the t2802 spa type were isolated from both farmers and rabbits. Age categories harboured significantly different pathotypes (p = 0.019), while no association was found between pathotypes and lesions (p = 0.128) or sampling sites (p = 0.491). The antibiotic resistance was observed to increase with the time spent in the farm environment (age category). The selective pressure exerted by antibiotic use acted by giving advantage to more resistant strains rather than by lowering susceptibility to various drug categories within strains

Hydrogen blending effect on fiscal and metrological instrumentation: A review

A green hydrogen (H2) economy requires a sustainable, efficient, safe, and widespread infrastructure for transporting and distributing H2 from production to consumption sites. Transporting a hydrogen/natural gas (H2NG) mixture, including pure H2, through the existing European natural gas (NG) infrastructure is considered a cost-effective solution, particularly in the transitional phase. Several reasons justify the H2NG blending option. The NG infrastructure can be efficiently repurposed to transport H2, by blending H2 with NG, to operate as H2 daily storage, matching production and demand and to enable large-scale seasonal H2 storage. Although many benefits exist, the potential of existing NG grids for transporting and distributing green H2 may face limitations due to technical, economic, or normative concerns. This paper focuses on the state of the art of the European NG transmission and distribution metrology normative framework and identifies the gaps to be filled in case of H2NG flowing into the existing grids. The paper was revised to provide a comprehensive analysis of the practical implications resulting from the H2NG blend option