Angular Spectrum Analysis Applied to Undercladding Flaws and Dipole Probes

An important class of subsurface cracks occur in nuclear power plant pressure vessels. These pressure vessels, normally made of carbon steel, are protected by a layer of weld material applied directly onto the surface, leaving a highly inhomogeneoue cladding with a rough surface and a very irregular interface. Subsurface cracks originate at the interface between the carbon steel walls of the pressure vessel and the protective cladding layer. The propagation is initially into the carbon steel and eventually into the cladding, and needs to be detected before reaching the surface (Fig. 1). The inhomogeneity of the cladding material and the irregular surfaces pose serious difficulties for ultrasonic detection. These difficulties are less critical for eddy current testing due to the fact that the layered structure of the cladding has more variation in its elastic properties than its electrical conductivity

Eddy-Current Detection Methods for Surface-Breaking Tight Cracks

The eddy-current (EC) NDE method has been in use for quite some time, and efforts have been made to make it a fully quantitative method. To evaluate impedance signals for a given EC inspection system, one has to characterize the system as a whole, including both probes and specimens. In particular, until probes are characterized, the electromagnetic fields cannot be calculated. Naturally, the amount of numerical computation becomes a serious issue during the course of development. It is necessary to choose probes carefully so as to maximize the flaw-characterization capability, while keeping numerical tasks within a reasonable size. Probes that are suitable for quantitative assessment are presumably different in nature from those with maximum detection capability. Among all kinds of existing probes, the simplest characterizable probe is the uniform-field-eddy-current (UFEC) probe. In fact, a series of studies, both theoretical and experimental, were devoted to demonstrating potential capabilities of UFEC probes [1–9]. The present theoretical work is another entry in this series. The numerical procedure developed in this work is limited to the case where cracks are tightly closed. The procedure is nevertheless capable, in principle, of dealing with an arbitrary range of frequencies

Inversion of Eddy Current Signals in a Nonuniform Probe Field

We present a simple analytical method for predicting the eddy current signal (ΔZ) produced by a surface flaw of known dimensions, when interrogated by a probe with spatially varying magnetic field. The model is easily parameterized, and we use it to construct inversion schemes which can extract overall flaw dimensions from multiposition, multifrequency measurements. Our method is a type of Born approximation, in which we assume that the probe’s magnetic field at the mouth of the flaw can be used as a boundary condition on the electromagnetic field solutions inside the flaw. To simplify the calculation we have chosen a “rectangular” 3-dimensional flaw geometry for our model. We describe experimental measurements made with a new broadband probe on a variety of flaws. This probe operates in a frequency range of 200 kHz to 20 MHz and was designed to make the multifrequency measurements necessary for inversion purposes. Since inversion requires knowledge of the probe’s magnetic field shape, we describe experimental methods which determine the interrogating field geometry for any eddy current probe

Frequency Dependence of Electric Current Perturbation Probe Response

The electric current perturbation (ECP) probe1–3 is similar to a conventional eddy current probe in that a coil, typically a cylindrical winding, is used to induce current in the test piece. The ECP probe differs in the use of a separate differential sensor coil, with axis parallel to the surface of the piece, and usually located just outside the induction coil winding. We have found that this sensor orientation tends to minimize probe-to-surface coupling and therefore minimizes liftoff noise

NUCB2/Nesfatin-1 Reduces Obesogenic Diet Induced Inflammation in Mice Subcutaneous White Adipose Tissue

Data Availability Statement: Data are available via the corresponding authors upon reasonable request that does not raise any ethical, privacy, or security concerns.Copyright: © 2022 by the authors. Background: Excess adipose tissue accumulation and obesity are characterised by chronic, low-grade, systemic inflammation. Nestfatin-1 is a neuropeptide derived from the precursor protein nucleobindin-2 (NUCB2), which was initially reported to exert anorexigenic effects. The present study aimed to investigate the effects of an obesogenic diet (OD; high-fat, high-sugar) in NUCB2 knockout (KO) mice and of nesfatin-1 treatment in LPS-stimulated 3T3-L1 preadipocytes. Methods: Subcutaneous white adipose tissue (Sc-WAT) samples from wild type (WT) and NUCB2 KO mice that were fed a normal diet (ND), or the OD for 12 weeks were used for RNA and protein extraction, as well as immunohistochemistry. 3T3-L1 cells were treated with 100 nM nesfatin-1 during differentiation and stimulated with 1 µg/mL LPS for measuring the expression and secretion of pro-inflammatory mediators by qPCR, western blotting, immunofluorescence, Bioplex, and ELISA. Results: Following the OD, the mRNA, protein and cellular expression of pro-inflammatory mediators (Tnfα, Il-6, Il-1β, Adgre1, Mcp1, TLR4, Hmbgb1 and NF-kB) significantly increased in the ScWAT of NUCB2 KO mice compared to ND controls. Adiponectin and Nrf2 expression significantly decreased in the ScWAT of OD-fed NUCB2 KO, without changes in the OD-fed WT mice. Furthermore, nesfatin-1 treatment in LPS-stimulated 3T3-L1 cells significantly reduced the expression and secretion of pro-inflammatory cytokines (Tnfα, Il-6, Il-1β, Mcp1) and hmgb1. Conclusion: An obesogenic diet can induce significant inflammation in the ScWAT of NUCB2 KO mice, involving the HMGB1, NRF2 and NF-kB pathways, while nesfatin-1 reduces the pro-inflammatory response in LPS-stimulated 3T3-L1 cells. These findings provide a novel insight into the metabolic regulation of inflammation in WAT.This research received no external funding

Elastic Characterization of Orthotropic Composite Materials from Ultrasonic Inspection through Non-Principal Planes

Transmission of bulk ultrasonic waves through materials immersed in water is a well appropriated method to measure the stiffness matrix of anisotropic composite materials. This matrix can be deduced from velocities measurements by simple [1,2,3] or double transmission [4,5] or from amplitudes of double reflected bulk waves [4]. All these methods are working very well for unidirectional composites when transverse isotropy is assumed and the stiffness matrix has only five independent elastic constants.</p

Disparities in the frequency of fruit and vegetable consumption by socio-demographic and lifestyle characteristics in Canada

<p>Abstract</p> <p>Background</p> <p>The health benefits of adequate fruit and vegetable (F&V) consumption are significant and widely documented. However, many individuals self-report low F&V consumption frequency per day. This paper examines the disparities in the frequency of F&V consumption by socio-demographic and lifestyle characteristics.</p> <p>Method</p> <p>This study uses a representative sample of 93,719 individuals from the Canadian Community Health Survey (2007). A quantile regression model is estimated in order to capture the differential effects of F&V determinants across the conditional distribution of F&V consumption.</p> <p>Results</p> <p>The conditional and unconditional analyses reveal the existence of a socioeconomic gradient in F&V consumption frequency, in which the low income-education groups consume F&V less frequently than the high income-education groups. We also find significant disparities in F&V consumption frequency by demographic and lifestyle characteristics. The frequency of F&V consumption is relatively lower among: males, those in middle age, singles, smokers, individuals with weak social interaction and households with no children. The quantile regression results show that the association between F&V consumption frequency, and socio-demographic and lifestyle factors varies significantly along the conditional F&V consumption distribution. In particular, individual educational attainment is positively and significantly associated with F&V consumption frequency across different parts of the F&V distribution, while the income level matters only over the lower half of the distribution. F&V consumption follows a U-shaped pattern across the age categories. Those aged 30-39, 40-49 and 50-59 years consume F&V less frequently than those aged 18-29 years. The smallest F&V consumption is among the middle aged adults (40-49).</p> <p>Conclusions</p> <p>Understanding the socio-demographic and lifestyle characteristics of individuals with low F&V consumption frequency could increase the effectiveness of policies aimed at promoting F&V consumption. The differential effects of individual characteristics along the F&V consumption distribution suggest the need for a multifaceted approach to address the variation in F&V consumption frequency.</p

Predictive Models and Reliability Improvement in Electromagnetic Nondestructive Evaluation

The role of theory in improving the reliability of electromagnetic NDE is generally the same as with other inspection methods.1-4 Computational models of the interaction of NDE probes with material flaws can be used to aid in the selection of a method, including details of the probe design, in the verification of the method, by providing data on flaw response, and in the development and analysis of an inspection plan in terms of probability of detection (POD) data. In this paper we will first give examples of how these three aspects of reliability improvement can be accomplished through the use of theoretical models. Then, in the second part of the paper, we will comment on the adequacy of existing models and offer some suggestions for further model development for reliability applications.</p

Glial Processes at the Drosophila Larval Neuromuscular Junction Match Synaptic Growth

Glia are integral participants in synaptic physiology, remodeling and maturation from blowflies to humans, yet how glial structure is coordinated with synaptic growth is unknown. To investigate the dynamics of glial development at the Drosophila larval neuromuscular junction (NMJ), we developed a live imaging system to establish the relationship between glia, neuronal boutons, and the muscle subsynaptic reticulum. Using this system we observed processes from two classes of peripheral glia present at the NMJ. Processes from the subperineurial glia formed a blood-nerve barrier around the axon proximal to the first bouton. Processes from the perineurial glial extended beyond the end of the blood-nerve barrier into the NMJ where they contacted synapses and extended across non-synaptic muscle. Growth of the glial processes was coordinated with NMJ growth and synaptic activity. Increasing synaptic size through elevated temperature or the highwire mutation increased the extent of glial processes at the NMJ and conversely blocking synaptic activity and size decreased the presence and size of glial processes. We found that elevated temperature was required during embryogenesis in order to increase glial expansion at the nmj. Therefore, in our live imaging system, glial processes at the NMJ are likely indirectly regulated by synaptic changes to ensure the coordinated growth of all components of the tripartite larval NMJ

Structural Differences between the Streptococcus agalactiae Housekeeping and Pilus-Specific Sortases: SrtA and SrtC1

The assembly of pili on the cell wall of Gram-positive bacteria requires transpeptidase enzymes called sortases. In Streptococcus agalactiae, the PI-1 pilus island of strain 2603V/R encodes two pilus-specific sortases (SrtC1 and SrtC2) and three pilins (GBS80, GBS52 and GBS104). Although either pilus-specific sortase is sufficient for the polymerization of the major pilin, GBS80, incorporation of the minor pilins GBS52 and GBS104 into the pilus structure requires SrtC1 and SrtC2, respectively. The S. agalactiae housekeeping sortase, SrtA, whose gene is present at a different location and does not catalyze pilus polymerization, was shown to be involved in cell wall anchoring of pilus polymers. To understand the structural basis of sortases involved in such diverse functions, we determined the crystal structures of S. agalactiae SrtC1 and SrtA. Both enzymes are made of an eight-stranded beta-barrel core with variations in their active site architecture. SrtA exhibits a catalytic triad arrangement similar to that in Streptococcus pyogenes SrtA but different from that in Staphylococcus aureus SrtA. In contrast, the SrtC1 enzyme contains an N-terminal helical domain and a ‘lid’ in its putative active site, which is similar to that seen in Streptococcus pneumoniae pilus-specific sortases, although with subtle differences in positioning and composition. To understand the effect of such differences on substrate recognition, we have also determined the crystal structure of a SrtC1 mutant, in which the conserved DP(W/F/Y) motif was replaced with the sorting signal motif of GBS80, IPNTG. By comparing the structures of WT wild type SrtA and SrtC1 and the ‘lid’ mutant of SrtC1, we propose that structural elements within the active site and the lid may be important for defining the role of specific sortase in pili biogenesis