Acoustic effects at prehistoric landscapes: an archaeoacoustics analysis of rock art sites from Western Mediterranean

Many pre-state societies around the world give special importance to places where distinctive acoustic effects are generated. These places often receive special treatment including the production of rock paintings in them. In the Western Mediterranean, it seems that outstanding acoustic effects such as directional echoes, augmented audibility and long reverberation time are present in some rock art areas with Neolithic depictions made between the 7th and 4th millennia BC. These have been painted in different styles that have been given the name of Macroschematic, Levantine and Schematic rock art styles. On the basis of the results of our acoustic tests, we argue that there is a strong probability of acoustics having been used as a method by Neolithic artists to select the shelters in which to produce rock art. This paper presents the results of the ongoing ARTSOUNDSCAPES ERC Project on archaeoacoustics. This project seeks to explore the role of sound in the creation and use of rock art sites. he authors discuss the results of previous fieldwork in three countries (Spain, France and Italy) and the development of an innovative set of research methods that include 3D Ambisonic recordings, GIS soundshed analysis, and Transmission Loss measurements

Progressive Structural Defects in Canine Centronuclear Myopathy Indicate a Role for HACD1 in Maintaining Skeletal Muscle Membrane Systems

Mutations in HACD1/PTPLA cause recessive congenital myopathies in humans and dogs. Hydroxyacyl-coA dehydratases are required for elongation of very long chain fatty acids, and HACD1 has a role in early myogenesis, but the functions of this striated muscle-specific enzyme in more differentiated skeletal muscle remain unknown. Canine HACD1 deficiency is histopathologically classified as a centronuclear myopathy (CNM). We investigated the hypothesis that muscle from HACD1-deficient dogs has membrane abnormalities in common with CNMs with different genetic causes. We found progressive changes in tubuloreticular and sarcolemmal membranes and mislocalized triads and mitochondria in skeletal muscle from animals deficient in HACD1. Furthermore, comparable membranous abnormalities in cultured HACD1-deficient myotubes provide additional evidence that these defects are a primary consequence of altered HACD1 expression. Our novel findings, including T-tubule dilatation and disorganization, associated with defects in this additional CNM-associated gene provide a definitive pathophysiologic link with these disorders, confirm that dogs deficient in HACD1 are relevant models, and strengthen the evidence for a unifying pathogenesis in CNMs via defective membrane trafficking and excitation-contraction coupling in muscle. These results build on previous work by determining further functional roles of HACD1 in muscle and provide new insight into the pathology and pathogenetic mechanisms of HACD1 CNM. Consequently, alterations in membrane properties associated with HACD1 mutations should be investigated in humans with related phenotypes

Cellular shear adhesion force measurement and simultaneous imaging by atomic force microscope

This paper presents a sensitive and fast cellular shear adhesion force measurement method using an atomic force microscope (AFM). In the work, the AFM was used both as a tool for the imaging of cells on the nano-scale and as a force sensor for the measurement of the shear adhesion force between the cell and the substrate. After the cell imaging, the measurement of cellular shear adhesion forces was made based on the different positions of the cell on the nano-scale. Moreover, different pushing speeds of probe and various locations of cells were used in experiments to study their influences. In this study, the measurement of the cell adhesion in the upper portion of the cell is different from that in the lower portion. It may reveal that the cancer cells have the metastasis tendency after cultured for 16 to 20 hours, which is significant for preventing metastasis in the patients diagnosed with early cancer lesions. Furthermore, the cellular shear adhesion forces of two types of living cancer cells were obtained based on the measurements of AFM cantilever deflections in the torsional and vertical directions. The results demonstrate that the shear adhesion force of cancer cells is twice as much as the same type of cancer cells with TRAIL. The method can also provide a way for the measurement of the cellular shear adhesion force between the cell and the substrate, and for the simultaneous exploration of cells using the AFM imaging and manipulatio

HVOF-Deposited WCCoCr as Replacement for Hard Cr in Landing Gear Actuators

WCCoCr coatings deposited by HVOF can replace hard Cr on landing gear components. Powders with two different WC particle sizes (micro and nano-) and geometries have been employed to study the effects on the coating’s properties. Moreover, coatings produced employing two sets of parameters resulting in high and low flame temperatures have been evaluated. Minor differences in microstructure and morphology were observed for the two powders employing the same spraying parameters, but the nano-sized powder exhibited a higher spraying efficiency. However, more significant microstructural changes result when the low- and high-energy spray parameters are used. Moreover, results of various tests which include adhesion, wear, salt fog corrosion resistance, liquid immersion, and axial fatigue strength, indicate that the coatings produced with high-energy flame are similar in behavior. On the other hand, the nanostructured low-energy flame coating exhibited a significantly lower salt fog corrosion resistanc

A comparative study of precision finishing of rebuild engine valve faces using micro-grinding and ECH

This paper presents a comparative analysis of process performance of micro-grinding and electrochemical honing, with the aim to achieve higher precision and surface quality of rebuild surfaces of the engine valve face. The discarded engine valve face was rebuilt using plasma transferred arc cladding technique and its surface finish was evaluated in terms of average roughness and maximum roughness value. The improvement in profile error and total run-out were used to evaluate the optimum processing time of micro-grinding and ECH. The sets of experiments for micro-grinding and ECH were conducted. The results reveal that the ECH process is one of the ideal choice for finishing of recovered surfaces. The surface morphology of the processed part is significantly improved resulting in glazed and uniform texture. Results show that the ECH can produce the workpiece surface 75 % efficient than the micro-grinding. A significant improvement of 23.37 % in the average surface roughness value was found after ECH as compared with the micro-grinding

Ions modulate stress-induced nano-texture in supported fluid lipid bilayers.

Most plasma membranes comprise a large number of different molecules including lipids and proteins. In the standard fluid mosaic model, the membrane function is effected by proteins whereas lipids are largely passive and serve solely in the membrane cohesion. Here we show, using supported 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid bilayers in different saline solutions, that ions can locally induce ordering of the lipid molecules within the otherwise fluid bilayer when the latter is supported. This nanoordering exhibits a characteristic length scale of ∼20 nm, and manifests itself clearly when mechanical stress is applied to the membrane. Atomic force microscopy (AFM) measurements in aqueous solutions containing NaCl, KCl, CaCl2, and Tris buffer show that the magnitude of the effect is strongly ion-specific, with Ca2+ and Tris, respectively, promoting and reducing stress-induced nanotexturing of the membrane. The AFM results are complemented by fluorescence recovery after photobleaching experiments, which reveal an inverse correlation between the tendency for molecular nanoordering and the diffusion coefficient within the bilayer. Control AFM experiments on other lipids and at different temperatures support the hypothesis that the nanotexturing is induced by reversible, localized gel-like solidification of the membrane. These results suggest that supported fluid phospholipid bilayers are not homogenous at the nanoscale, but specific ions are able to locally alter molecular organization and mobility, and spatially modulate the membrane’s properties on a length scale of ∼20 nm. To illustrate this point, AFM was used to follow the adsorption of the membrane-penetrating antimicrobial peptide Temporin L in different solutions. The results confirm that the peptides do not absorb randomly, but follow the ion-induced spatial modulation of the membrane. Our results suggest that ionic effects have a significant impact for passively modulating the local properties of biological membranes, when in contact with a support such as the cytoskeleton

Effect of particle and carbide grain sizes on a HVOAF WC-Co-Cr coating for the future application on internal surfaces: microstructure and wear

The use of nanoscale WC grain or finer feedstock particles are possible methods of improving the performance of WC-Co-Cr coatings. Finer powders are being pursued for the development of coating internal surfaces, as less thermal energy is required to melt the finer powder compared to coarse powders, permitting spraying at smaller stand - off distances. Three WC-0Co-4Cr coatings, with two different powder particle sizes and two different carbide grain sizes, were sprayed using a high velocity oxy-air fuel (HVOAF) thermal spray system developed by Castolin Eutectic - Monitor Coatings Ltd., UK. Powder and coating microstructures were characterised using XRD and SEM. Fracture toughness and dry sliding wear performance at three loads were investigated using a ball–on-disc tribometer with a WC–Co counter body. It was found that the finer powder produced the coating with the highest microhardness, but its fracture toughness was reduced due to increased decarburisation compared to the other powders. The sprayed nanostructured powder had the lowest microhardness and fracture toughness of all materials tested. Unlubricated sliding wear testing at the lowest load showed the nanostructured coating performed best; however at the highest load this coating showed the highest specific wear rates with the other two powders performing to a similar, better standard