Stability of rigid blocks exposed to single-pulse excitation

This paper proposes a numerical procedure that can predict the minimum duration of a rectangular, half-cycle sine wave, linearly increasing and triangular single-pulse excitation required to overturn the rigid block resting on a moving base. Since the linearization assumption in the derivation of an analytical solution, which has already been used by Housner and other researchers, cannot be valid for a block with various slenderness ratios and dimensions, a derivation of numerical solutions which would be valid for all types of block is necessary. The proposed numerical procedure takes into account the possibility of sliding and uplifting of the block from the base. The numerical algorithm for the proposed numerical procedure in a commercial code C++ is given in the “Appendix.”     

Virtual approach to holonic control of the tyre-manufacturing system

Tyre manufacturers aiming to remain competitive in complex modern markets must promptly adjust to the changes within the production environment. With traditional tyre-manufacturing systems, a slow response during optimization of the manufacturing process and low-level adaptability to system disturbances is evident. The presented approach to virtual holonic control of the tyre-manufacturing system enables dynamic response in the event of new optimization demands, decrease of the impact of disturbances on system productivity and smaller future investments in the manufacturing equipment.     

Aerodynamic design and analysis of a small-scale vertical axis wind turbine

Small-scale vertical axis wind turbines are regarded today as an attractive source of green energy, still insufficiently implemented and tested. This paper presents a fast design methodology of such a VAWT, in terms of choosing its main parameters: airfoil, rotor diameter and solidity. For obtaining generated power of each considered geometrical model at different undisturbed wind velocities and rotor angular velocities two models were used — momentum and vortex-wake model, combined with experimentally measured airfoil data (airfoil lift and drag coefficients). Even though the former model is simpler, it is the most utilized model, known to provide good results in stationary working regimes. Both models still present fairly accurate and fast tools for computation and optimization, particularly useful in the phase of conceptual design. In this research, the use of the momentum model resulted in determination of the maximal power coefficient, optimal- and minimal freestream velocity for every considered VAWT model. From these output parameters, a selection of the optimal geometric model was done, and a more detailed transient analysis and flow representation around the selected solution was obtained by the vortex-wake model. The results obtained by the two used computational models coincide satisfactorily.     

Effects of drilling parameters and aspect ratios on delamination and surface roughness of lignocellulosic HFRP composite laminates

Hemp fibre‐reinforced polycaprolactone (HFRP) composite has inherent good mechanical properties and benefits which include remarkably high specific strength and modulus, low density, and renewability. No doubt, these properties have attracted wider applications of HFRP composite in engineering applications. This paper presents an investigation on the influence of drilling parameters and fibre aspect ratios, AR (0, 19, 26, 30, and 38) on delamination damage factor and surface roughness of HFRP composite laminates utilising high speed steel twist drills under dry machining condition. Taguchi's technique was used in the design of experiment. The results obtained show that increase in cutting speed reduces delamination factor and surface roughness of drilled holes, whereas increase in feed rate causes increase in both delamination factor and surface roughness. Feed rate and cutting speed had the greatest influence on delamination and surface roughness respectively when compared with aspect ratio, while an increase in fibre aspect ratios leads to a significant increase in both delamination factor and surface roughness. The optimum results occurred at cutting speed and feed rate (drilling parameters) of 20 mm/min and 0.10 mm/rev, respectively, when drilling sample of AR 19. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42879.     

Multivalent Interactions between an Aromatic Helical Foldamer and a DNA G‐Quadruplex in the Solid State

Quinoline‐based oligoamide foldamers have been identified as a potent class of ligands for G‐quadruplex DNA. Their helical structure is thought to target G‐quadruplex loops or grooves and not G‐tetrads. We report a co‐crystal structure of the antiparallel hairpin dimeric DNA G‐quadruplex (G₄T₄G₄)₂ with tetramer 1 —a helically folded oligo‐quinolinecarboxamide bearing cationic side chains—that is consistent with this hypothesis. Multivalent foldamer–DNA interactions that modify the packing of (G₄T₄G₄)₂ in the solid state are observed.     

Candida albicans homologue of GGP1/GAS1 gene is functional in Saccharomyces cerevisiae and contains the determinants for glycosylphosphatidylinositol attachment

The GGP1/GAS1/CWH52 gene of Saccharomyces cerevisiae encodes a major exocellular 115 kDa glycoprotein (gp115) anchored to the plasma membrane through a glycosylphosphatidylinositol (GPI). The function of gp115 is still unknown but the analysis of null mutants suggests a possible role in the control of morphogenesis. PHR1 gene isolated from Candida alibicans is homologous to the GGP1 gene. In this report we have analysed the ability of PHR1 to complement a ggp1Δ mutation in S. cerevisiae. The expression of PHR1 controlled by its natural promoter or by the GGP1 promoter has been studied. In both cases we have observed a complete complementation of the mutant phenotype. Moreover, immunological analysis has revealed that PHR1 in budding yeast gives rise to a 75–80 kDa protein anchored to the membrane through a GPI, indicating that the signal for GPI attachment present in the C. albicans gene product is functional in S. cerevisiae.     

Morphometry and Stiffness of Red Blood Cells—Signatures of Neurodegenerative Diseases and Aging

Human red blood cells (RBCs) are unique cells with the remarkable ability to deform, which is crucial for their oxygen transport function, and which can be significantly altered under pathophysiological conditions. Here we performed ultrastructural analysis of RBCs as a peripheral cell model, looking for specific signatures of the neurodegenerative pathologies (NDDs)—Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD), utilizing atomic force (AFM) and conventional optical (OM) microscopy. We found significant differences in the morphology and stiffness of RBCs isolated from patients with the selected NDDs and those from healthy individuals. Neurodegenerative pathologies’ RBCs are characterized by a reduced abundance of biconcave discoid shape, lower surface roughness and a higher Young’s modulus, compared to healthy cells. Although reduced, the biconcave is still the predominant shape in ALS and AD cells, while the morphology of PD is dominated by crenate cells. The features of RBCs underwent a marked aging-induced transformation, which followed different aging pathways for NDDs and normal healthy states. It was found that the diameter, height and volume of the different cell shape types have different values for NDDs and healthy cells. Common and specific morphological signatures of the NDDs were identified.     

Functional and chemical characterization of the aging process of an igniter

The igniter consisting of 34% Mg, 60% KNO₃, 3% KClO₄ and 3% organic binder was subjected to accelerated aging under the conditions of 85% relative humidity at 65°C, 75°C and 85°C, and at 75°C with 92% relative humidity. Chemical aging was followed through formation of Mg(OH)₂ and KNO₂. Functional characterization was accomplished in a device constructed to enable simultaneous determination of the heat of combustion and pressure-time recording of the combustion process of both fresh and aged samples. The maximum acceptable deterioration occured at different times depending upon the conditions. The acceleration factor for every 10°C at 85% relative humidity is on average 2.8, leading to a prediction of shelf life of not more than 4 years at 25°C. At the time when burning characteristics were significantly changed, the mixture suffered only slight chemical changes, with only about 1% Mg(OH)₂ and 0.5% KNO₂ being formed. Thus, no chemical changes should be tolerated in such formulations.