Evaluation of four numerical wind flow models for wind resource mapping

A wide range of numerical wind flow models are available to simulate atmospheric flows. For wind resource mapping, the traditional approach has been to rely on linear Jackson–Hunt type wind flow models. Mesoscale numerical weather prediction (NWP) models coupled to linear wind flow models have been in use since the end of the 1990s. In the last few years, computational fluid dynamics (CFD) methods, in particular Reynolds‐averaged Navier–Stokes (RANS) models, have entered the mainstream, whereas more advanced CFD models such as large‐eddy simulations (LES) have been explored in research but remain computationally intensive. The present study aims to evaluate the ability of four numerical models to predict the variation in mean wind speed across sites with a wide range of terrain complexities, surface characteristics and wind climates. The four are (1) Jackson–Hunt type model, (2) CFD/RANS model, (3) coupled NWP and mass‐consistent model and (4) coupled NWP and LES model. The wind flow model predictions are compared against high‐quality observations from a total of 26 meteorological masts in four project areas. The coupled NWP model and NWP‐LES model produced the lowest root mean square error (RMSE) as measured between the predicted and observed mean wind speeds. The RMSE for the linear Jackson‐Hunt type model was 29% greater than the coupled NWP models and for the RANS model 58% greater than the coupled NWP models. The key advantage of the coupled NWP models appears to be their ability to simulate the unsteadiness of the flow as well as phenomena due to atmospheric stability and other thermal effects. Copyright © 2012 John Wiley & Sons, Ltd.     

Mechanical Characterization of Annealed ZrB2–SiC Composites

Composites consisting of 70 vol% ZrB₂ and 30 vol% α‐SiC particles were hot pressed to near full density and subsequently annealed at temperatures ranging from 1000°C to 2000°C. Strength, elastic modulus, and hardness were measured for as‐processed and annealed composites. Raman spectroscopy was employed to measure the thermal residual stresses within the silicon carbide (SiC) phase of the composites. Elastic modulus and hardness were unaffected by annealing conditions. Strength was not affected by annealing at 1400°C or above; however, strength increased for samples annealed below 1400°C. Annealing under uniaxial pressure was found to be more effective than annealing without applied pressure. The average strength of materials annealed at 1400°C or above was ~700 MPa, whereas that of materials annealed at 1000°C, under a 100 MPa applied pressure, averaged ~910 MPa. Raman stress measurements revealed that the distribution of stresses in the composites was altered for samples annealed below 1400°C resulting in increased strength.     

A Tetraene Aldehyde as the Major Sex Pheromone Component of the Promethea Moth (Callosamia promethea (Drury))

The promethea moth Callosamia promethea is one of three species of silkmoths from the genus Callosamia that occur in North America. Cross attraction of males to heterospecific calling females has been observed in the field, and hybrid progeny have been produced by pairing heterospecifics in captivity. These observations suggest that all three species share or have considerable overlap in the sex attractant pheromones produced by females, so that other prezygotic isolating mechanisms, such as diel differences in reproductive activity, limit hybridization in the field. Coupled gas chromatography-electroantennogram detection and gas chromatography- mass-spectrometry analyses of extracts of volatiles collected from female promethea moths supported the identification of (4E,6E,11Z,13Z)-hexadeca-4,6,11,13-tetraenal [(4E,6E,11Z,13Z)-16:Ald] as the compound in extracts that elicited the largest responses from antennae of males. The identification was confirmed by non-selective synthesis of several isomers as analytical standards, and stereoselective synthesis of (4E,6E,11Z,13Z)-16:Ald for testing in field trials. Male moths were strongly attracted to synthetic (4E,6E,11Z,13Z)-16:Ald, suggesting that this compound is the major and possibly the only component of the sex pheromone of these large saturniid moths. Based on the cross-attraction of heterospecifics, it is likely that this is also a major pheromone component of the other two North American Callosamia species as well.     

Hydroxytyrosol inhibits the proliferation of human colon adenocarcinoma cells through inhibition of ERK1/2 and cyclin D1

Extra virgin olive oil is rich in phenolic compounds which are believed to exert beneficial effects against many pathological processes, including the development of colon cancer. We show that one of the major polyphenolic constituents of extra virgin olive oil, hydroxytyrosol (HT), exerts strong antiproliferative effects against human colon adenocarcinoma cells via its ability to induce a cell cycle block in G2/M. These antiproliferative effects were preceded by a strong inhibition of extracellular signal‐regulated kinase (ERK)1/2 phosphorylation and a downstream reduction of cyclin D1 expression, rather than by inhibition of p38 activity and cyclooxygenase‐2 (COX‐2) expression. These findings are of particular relevance due to the high colonic concentration of HT compared to the other olive oil polyphenols and may help explain the inverse link between colon cancer and olive oil consumption.     

In vivo comparison of atherosclerotic plaque progression with vessel wall strain and blood flow velocity in apoE−/− mice with MR microscopy at 17.6 T

Object  At present, in vivo plaque characterization in mice by MRI is typically limited to the visualization of vascular lesions with no accompanying analysis of vessel wall function. The aim of this study was to analyze the influence of atherosclerotic plaque development on the morphological and mechanical characteristics of the aortic vessel wall in a pre-clinical murine model of atherosclerosis. Materials and methods  Groups of apolipoprotein E-deficient (apoE^−/−) and C57BL/6J control mice fed a high-fat diet were monitored over a 12-week time period by high-field MRI. Multi-Slice-Multi-Spin-Echo and Phase-Contrast MRI sequences were employed to track changes to aortic vessel wall area, blood flow velocity and distensibility. Results  After 6- and 12-weeks, significant changes in vessel wall area and circumferential strain were detected in the apoE^−/− mice relative to the control animals. Blood flow velocity and intravascular lumen remained unchanged in both groups, findings that are in agreement with the theory of positive remodeling of the ascending aorta during plaque progression. Conclusion  This study has demonstrated the application of high-field MRI for characterizing the temporal progression of morphological and mechanical changes to murine aortic vasculature associated with atherosclerotic lesion development.     

α‐Ketoheterocycles as Inhibitors of Leishmania mexicana Cysteine Protease CPB

Cysteine proteases of the papain superfamily are present in nearly all eukaryotes and also play pivotal roles in the biology of parasites. Inhibition of cysteine proteases is emerging as an important strategy to combat parasitic diseases such as sleeping sickness, Chagas disease, and leishmaniasis. Inspired by the in vivo antiparasitic activity of the vinylsulfone‐based cysteine protease inhibitors, a series of α‐ketoheterocycles were developed as reversible inhibitors of a recombinant L. mexicana cysteine protease, CPB2.8. Three isoxazoles and especially one oxadiazole compound are potent reversible inhibitors of CPB2.8; however, in vitro whole‐organism screening against a panel of protozoan parasites did not fully correlate with the observed inhibition of the cysteine protease.     

Injection molding with an additive manufactured tool

This study examines the viability of using additively manufactured injection molding tools for short run proof‐of‐concept plastic parts by assessing the quantity and quality of molded parts. Prototyping injection molded parts traditionally can be very expensive, but with improved additive manufacturing materials and techniques such costs could be reduced. To prove this, plastic tools were made by using PolyJet and Fused Deposition Modeling out of Digital ABS, FullCure 720, and ULTEM 1010 materials in this study. The test tools were then compared to the standard P20 metal tool by molding acetal, polycarbonate (PC), and polypropylene (PP) in each tool type. The molded parts were analyzed for processing effects on part shrink, physical, and mechanical properties. Testing concluded that parts molded with additively manufactured tools performed comparably to parts made on a P20 tool. However, the quantity of satisfactory parts molded in acetal and PC were consistent with the literature at 10–100 parts. Conversely, molding in PP suggested that processing with additive manufactured tools could exceed 250 parts. POLYM. ENG. SCI., 59:1911–1918, 2019. © 2019 Society of Plastics Engineers     

Characterization of microstructural strengthening in the heat-affected zone of a blast-resistant naval steel

The influence of simulated heat-affected zone thermal cycles on the microstructural evolution in a blast-resistant naval steel was investigated by dilatometry, microhardness testing, optical microscopy, electron backscatter diffraction and atom-probe tomography (APT) techniques. Coarsening of Cu precipitates were observed in the subcritical and intercritical heat-affected zones, with partial dissolution in the latter. A small number density of Cu precipitates and high Cu concentration in the matrix of the fine-grained heat-affected zone indicates the onset of Cu precipitate dissolution. Cu clustering in the coarse-grained heat-affected zone indicated the potential initiation of Cu reprecipitation during cooling. Segregation of Cu was also characterized by APT. The hardening and softening observed in the heat-affected zone regions was rationalized using available strengthening models.     

The influence of organizational tenure on safety climate strength: A first look

This study examined the relationship between the organizational tenure of employees at a given worksite and safety climate strength (i.e., the variability of employees’ perceptions of the policies, procedures, and practices regarding workplace safety). Results revealed that average worksite tenure was related to safety climate strength such that higher average tenure was associated with stronger safety climates. The moderating effect of tenure level on the relationship between tenure and climate strength was also examined. Results revealed a curvilinear relationship between mean worksite tenure and safety climate strength, such that at higher levels of worksite tenure, smaller increases in the group's average tenure improved climate strength to a greater extent than at lower levels of worksite tenure.