Multi-channel analysis of surface waves (MASW) using dispersion and iterative inversion techniques: implications for cavity detection and geotechnical site investigation

Bulletin of Engineering Geology and the Environment - Most of the surface wave-based geophysical methods require an accurate estimate of the shear wave velocity (Vs) for geotechnical site...     

Performance of sub‐cooled PEMFCs

Numerical simulations of a proton exchange membrane fuel cell were carried out for various temperatures ranging from well below the freezing temperature of water to a moderate ambient temperature, and also for various inlet temperatures, to investigate its performance. A three‐dimensional serpentine flow field was used to determine the cell behavior temperature conditions. The saturation of liquid water was considered for various ambient temperatures in order to obtain realistic estimates of cell performance, with special emphasis placed on sub‐cooled temperatures. Results show that both the ambient and the inlet temperature have strong influences on cell performance, although the inlet temperature has much more important influence than the ambient temperature. In addition, liquid water saturation is enhanced at higher inlet temperatures. Moreover, for sub‐cooled ambient temperatures the liquid saturation level is higher in the shoulder region near the inlet section than in the outlet section; this trend is reversed for higher ambient temperatures. There is a high probability that operation of the cell at sub‐cooled temperatures and higher inlet temperatures will result in the formation of ice throughout the system, which may further degrade the cell performance. The model was validated by comparison of predicted polarization curves with those found in the literature. Copyright © 2010 John Wiley & Sons, Ltd.     

Impact of Milk Derived β-Casomorphins on Physiological Functions and Trends in Research: A Review

β-Casomorphins are a group of opioid peptides released during gastrointestinal digestion or food processing from the β-casein of milk protein. Consequently, milk can be divided into A1 and A2 “like” groups depending upon the presence or absence of proline or histidine at the 67th position of β-casein. A1 “like” milk is postulated to be a source of BCM-7 as histidine allows the cleavage at this position, while A2 “like” milk has proline that resists the hydrolysis. On one hand, BCM-7 has been implicated as a risk factor for cardiovascular diseases, type I diabetes, and neurological disorders. On the other hand, various physiological effects of these peptides have also been documented, i.e., secretion of mucus, increased activity of superoxide dismutase and catalase, increased levels of prolactin, and analgesic role. In addition, many evidences correlate these peptides with various immunological functions, such as development of innate immunity, lymphocyte proliferation and cellular immunity, role in autoimmune diseases, histamine release, and allergy. In conclusion, the role of β-casomorphins in physiological functions remains controversial and more research with improved diagnostic techniques is needed to unravel the mechanism and study physiological functions of β-casomorphins. Thus, health-related aspects of β-casomorphins (positive, negative, and immunological impacts) have been comprehensively reviewed in this article.     

Simulation and test of a point focused electron beam emitter

We present the design analysis of a point focused electron beam emitter using numerical techniques. Simulation and modeling were performed followed by the calculation of emission parameters using programming codes EGUN and CST-PS. Beam emittance, average current density and perveance were calculated and are in agreement with the experimental values obtained at 10 kV acceleration potential. The emission parameters were evaluated up to 110 kV. This confirms possibilities of potential application of emitter for a linear accelerator.     

Temperature effect on the electrical properties of pyrolytic MnO2 thin films prepared from Mn(C2H3O2)2·4H2O

Spray deposited MnO₂ thin films onto glass substrate were subjected to a post-deposition heat treatment and the effects of temperature on electrical transport properties were studied in details. The heating and cooling cycles of the samples are reversible after successive heat-treatments in air and vacuum. The films were polycrystalline in structure and the oxygen chemisorption–desorption process was found to play an important role in controlling the electronic properties. Various grain-boundary and energy band parameters were calculated by taking conventional extrinsic semiconductor theory and grain boundary trapping models into account. The samples were non-degenerate n-type semiconductors. The transport properties are interpreted in terms of Seto's model which was proposed for polycrystalline semiconducting films. The inter-crystallite boundaries of the thin films play an important role in the transport properties.     

Fabrication of Nanoreaction Clusters with Dual‐Functionalized Protein Cage Nanobuilding Blocks

Fabrication of functional nanostructures is a prominent issue in nanotechnology, because they often exhibit unique properties that are different from the individual building blocks. Protein cage nanoparticles are attractive nanobuilding blocks for constructing nanostructures due to their well‐defined symmetric spherical structures, polyvalent nature, and functional plasticity. Here, a lumazine synthase protein cage nanoparticle is genetically modified to be used as a template to generate functional nanobuilding blocks and covalently display enzymes (β‐lactamase) and protein ligands (FKBP12/FRB) on its surface, making dual‐functional nanobuilding blocks. Nanoreaction clusters are subsequently created by ligand‐mediated alternate deposition of two complementary building blocks using layer‐by‐layer (LbL) assemblies. 3D nanoreaction clusters provide enhanced enzymatic activity compared with monolayered building block arrays. The approaches described here may provide new opportunities for fabricating functional nanostructures and nanoreaction clusters, leading to the development of new protein nanoparticle‐based nanostructured biosensor devices.     

The rolling texture of 18% Ni-350 maraging steel

Texture development in hot rolled sheet and hot forged tube of 18%Ni- 350 maraging steel has been studied after various degrees of cold deformation and flow turning, respectively. Hot rolled sheet exhibited considerable mechanical anisotropy. Weak texture development was observed following flow turning compared to cold deformation. Above 80% deformation, an increase in work hardening was accompanied by an increase in the orientation density of the texture component (001 )[110]. Deformation of 97% leads to the development of the texture component (111)[110], with the highest orientation density 10.3 times random and a constant orientation density of 9 times random along (φ1 at ϕ = 55° and φ2 = 45°. This texture was correlated with the appearance of shear bands in the microstructure.     

Stearic acid as interface modifier and lubricant agent of the system: Polypropylene/calcium carbonate nanoparticles

The toughness and the rheology of polypropylene (PP)‐calcium carbonate (CaCO₃) nanocompounds using stearic acid as an interface modifier were studied in this work. Compounding of the nanocomposites was carried out with a twin‐screw extruder. The benchmark samples (untreated) and stearic acid‐treated CaCO₃ nanoparticles were characterized by Fourier transform infrared (FTIR) spectroscopy. The nanocompounds were characterized by impact test, tensile test, scanning electron microscopy (SEM), rheological analysis, and differential scanning calorimetry (DSC). The elongation‐at‐break and impact resistance were increased in nanocompounds with interface modifier (stearic acid in hopper of the extruder). Nanocompounds with stearic acid showed the best dispersion state. Stearic acid helps to reduce complex viscosity acting as a lubricant, reducing frictional forces between nanoparticles of calcium carbonate (NCC) and PP chains. Nanocompounds with better dispersion state had crystallization temperatures very similar to the PP homopolymer. POLYM. ENG. SCI., 59:E279–E285, 2019. © 2019 Society of Plastics Engineers     

Landslide activity in Upper Palaeozoic shale sea cliffs: a case study along the western coast of the Algarve (Portugal)

A stretch of 48 km of sea cliffs up to 120 m high in the Algarve area of Portugal exposed heavily folded Palaeozoic shales. A study has been undertaken to assess the retreat of these sea cliffs. Nine sets of aerial photographs taken between 1947 and 1991 have been assessed, particularly to determine the retreat at the top of the cliffs. The time distribution of landslides shows some relationship with the average annual rainfall, and the space distribution provides a perspective of rates and patterns of cliff retreat in the different geographic locations. The landslides were predominantly planar, the larger ones having failure surfaces with a low dip consistent with long-term displacements at near residual strength. Examples are described. Back analysis indicates an average friction angle at the time of failure of between 23 and 25°, assuming negligible cohesion.