Multi-scale modelling of elastic moduli of trabecular bone

We model trabecular bone as a nanocomposite material with hierarchical structure and predict its elastic properties at different structural scales. The analysis involves a bottom-up multi-scale approach, starting with nanoscale (mineralized collagen fibril) and moving up the scales to sub-microscale (single lamella), microscale (single trabecula) and mesoscale (trabecular bone) levels. Continuum micromechanics methods, composite materials laminate theory and finite-element methods are used in the analysis. Good agreement is found between theoretical and experimental results.     

Preparation and characterization of poly(styrene‐co‐butadiene) and polybutadiene rubber/clay nanocomposites

Poly(styrene‐co‐butadiene) rubber (SBR) and polybutadiene rubber (BR)/clay nanocomposites have been prepared. The effects of the incorporation of inorganically and organically modified clays on the vulcanization reactions of SBR and BR were analysed by rheometry and differential scanning calorimetry. A reduction in scorch time (t_s1) and optimum time (t₉₅) was observed for both the rubbers when organoclay was added and this was attributed to the amine groups of the organic modifier. However, t_s1 and t₉₅ were further increased as the clay content was increased. A reduction in torque value was obtained for the organoclay nanocomposites, indicating a lower number of crosslinks formed. The organoclays favoured the vulcanization process although the vulcanizing effect was reduced with increasing clay content. The tensile strength and elongation of SBR were improved significantly with organoclay. The improvement of the tensile properties of BR with organoclay was less noticeable than inorganic‐modified clay. Nevertheless, these mechanical properties were enhanced with addition of clay. The mechanical properties of the nanocomposites were dependent on filler size and dispersion, and also compatibility between fillers and the rubber matrix. Copyright © 2004 Society of Chemical Industry     

Synthesis and Antimicrobial Evaluation of Some Novel Thiazole,Pyridone, Pyrazole,Chromene, Hydrazone Derivatives Bearing a Biologically Active Sulfonamide Moiety

This study aimed for the synthesis of new heterocyclic compounds incorporating sulfamoyl moiety suitable for use as antimicrobial agents via a versatile, readily accessible N-[4-(aminosulfonyl)phenyl]-2-cyanoacetamide (3). The 2-pyridone derivatives were obtained via reaction of cyanoacetamide with acetylacetone or arylidenes malononitrile. Cycloaddition reaction of cyanoacetamide with salicyaldehyde furnished chromene derivatives. Diazotization of 3 with the desired diazonium chloride gave the hydrazone derivatives 13a–e. Also, the reactivity of the hydrazone towards hydrazine hydrate to give Pyrazole derivatives was studied. In addition, treatment of 3 with elemental sulfur and phenyl isothiocyanate or malononitrile furnished thiazole and thiophene derivatives respectively. Reaction of 3 with phenyl isothiocyanate and KOH in DMF afforded the intermediate salt 17 which reacted in situ with 3-(2-bromoacetyl)-2H-chromen-2-one and methyl iodide afforded the thiazole and ketene N,S-acetal derivatives respectively. Finally, reaction of 3 with carbon disulfide and 1,3-dibromopropane afforded the N-[4-(aminosulfonyl) phenyl]-2-cyano-2-(1,3-dithian-2-ylidene)acetamide product 22. All newly synthesized compounds were elucidated by considering the data of both elemental and spectral analysis. The compounds were evaluated for both their in vitro antibacterial and antifungal activities and showed promising results.     

A study of carboxylic acids and nano-TiO2 effects on stress relaxation of cotton fabrics

This study presents an evaluation on stress relaxation of cotton fabrics before and after performing the finishing process. The process includes a series of treatments on fabric samples through the Pad-dry curing method. A group of organic acids along with a proportion of catalyst and co-catalyst mixture constituted the treatment agents. Stress relaxation behavior of untreated and treated samples was assessed along two different directions of weft and warp using stress relaxation tester. In addition, an Italian Mesdan tensile tester was applied to measure physical and mechanical properties such as elongation, strength, Poisson’s ratio, and shear modulus. In the mean time scanning electron microscopy was applied to consider surface of samples before and after treatments. The results prove that the stress relaxation of treated samples has shown reasonably acceptable values when compared with those obtained for untreated one. Furthermore, the curve fitting of Maxwell’s model over the experimental data also justified that an interlaced model is more appropriate for explaining the stress relaxation in cotton fabrics. Beside the result of stress relaxation, Poisson’s ratio, and shear modulus illustrated remarkable increments. On the other hand, a reverse trend was observed for tensile properties in both directions. Orthotropic feature evaluation of fabrics toward both the direction of warp and weft also infers different response of stress relaxation in each direction.     

Parallelizing quantum circuits

We present a novel automated technique for parallelizing quantum circuits via the forward and backward translation to measurement-based quantum computing patterns, and analyze the trade off in terms of depth and space complexity. As a result we distinguish a class of polynomial depth circuits that can be parallelized to logarithmic depth while adding only a polynomial number of auxiliary qubits. In particular, we provide for the first time a full characterization of patterns with flow of arbitrary depth, based on the notion of influencing walks and a simple rewriting system on the angles of the measurement. Our method provides new insight for constructing parallel circuits and as applications, we demonstrate several classes of circuits that can be parallelized to constant or logarithmic depth. Furthermore, we prove a logarithmic separation in terms of quantum depth between the quantum circuit model and the measurement-based model.     

Stability crossing surfaces for linear time-delay systems with three delays

In this article, the stability of linear systems with time-delays is studied. The cases where the characteristic equations of the system include three delays are investigated. Using the geometrical relations in a normalised polynomial plane, a graphical method is presented to visualise the stability domains in the space of the time-delays. In this space, the points at which the characteristic equation has a zero on the imaginary axis (the border between stability and instability regions) are identified. These points form several surfaces called the ‘stability crossing surfaces’. This work extends the results of the previous works on the ‘stability crossing curves’ defined in the two-dimensional space (plane) of delays to a higher dimension and provides new geometric interpretations for the stability crossing conditions.     

The OTIS hyper hexa-cell optoelectronic architecture

Optical transpose interconnection system (OTIS) is an optoelectronic architecture that promises to be a great choice for future-generation parallel systems. OTIS combines the advantages of electronic and optical links, where electronic links are used for short distances which require low material cost, and optical links are used for long distances which provide high speed network with low power consumption. Taking into account the advantageous characteristics of OTIS and based on the attractive properties of hyper hexa-cell (HHC) interconnection topology from low diameter and good minimum node degree, this paper introduces a new optoelectronic architecture referred to as OTIS hyper hexa-cell (OHHC). This paper also provides an evaluation and a comparison of the new topology with OTIS-mesh in terms of the following topological properties: size, diameter, maximum and minimum node degree, bisection width, total cost and optical cost. The results of this study proved the excellence of the proposed OHHC over OTIS-mesh in terms of diameter, minimum node degree, bisection width, and optical cost.     

Polyaniline grafted chitosan/GO-CNT/Fe3O4 nanocomposite as a superior electrode material for supercapacitor application

Developing appropriate stable electroactive electrode materials for supercapacitor application is the challenging issue, which attracts enormous attention in recent decades. In this regard, Fe₃O₄ nanoparticles are firstly synthesized on chitosan/graphene oxide-multiwall carbon nanotubes (CS/GM/Fe₃O₄). Then, polyaniline (PANI) is grafted on it via in situ chemical polymerization and named as CS/GM/Fe₃O₄/PANI. The as-prepared nanocomposites are characterized by Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. The capacitive properties of the electrodes are investigated in a three electrode configuration in 0.5 M Na₂SO₄ electrolyte by various electrochemical techniques. The specific capacitance of CS/GM/Fe₃O₄/PANI electrode is 1513.4 Fg⁻¹ at 4 Ag⁻¹ which is 1.9 times higher than that of CS/GM/Fe₃O₄ (800 Fg⁻¹). Meanwhile, the electrodes exhibit appropriate cycle life along with 99.8% and 93.95% specific capacitance at 100 Ag⁻¹ for chitosan/GO-CNT/Fe₃O₄ and polyaniline grafted chitosan/GO-CNT/Fe₃O₄, respectively.     

Photoluminescence study of SBA-15@ZnO/Au nanocomposite for potential use in Staphylococcus aureus detection

Journal of Porous Materials - Staphylococcus aureus is most common causes of hospital-acquired infections and food-associated disease. In the last years, sensing platform based on fluorescence-...