Tensile strength prediction of irregular fibres using diameter-dependent Weibull analysis

A modified Weibull model incorporating the within-fibre diameter variation is applied to examine the fibre diameter effect on the strength of single fibres. Australian Superfine Merino Wool (ASFW) and Inner Mongolia Cashmere (IMC) were used in the present work, since these animal fibres tend to have relatively large diameter variations. To determine single fibre strength, tensile measurements were carried out for fibres with diameters varying between 9 and 21?μm at a constant gauge length. It was found that an increase in the diameter disparity along the fibre reduces the strength of fibres. To validate this, the accuracy of predicting weak-link scaling was evaluated; the results showed that the application of modified Weibull distribution gives a better relationship with the empirical data than the standard Weibull model. The results suggest that the modified Weibull model is more accurate in predicting the size dependence and strength of single fibres with diameter variations.     

Numerical investigation of non‐Newtonian nanofluid mixed convection in a two‐opposite direction lid‐driven cavity with variable properties

The mixed convection fluid flow in a square cavity filled with AL₂O₃‐water non‐Newtonian nanofluid is numerically analyzed. The left and right vertical boundaries of the enclosure have been kept in the constant temperature. Remaining walls of the cavity have been considered to have adiabatic boundary condition. Two different cases have been considered. In the first case, left and right side walls have been moved vertically with constant speed V_b in opposite directions. In the second case, the directions of their motions have been reversed. The transport equations, written in terms of the primitive variables for the non‐Newtonian nanofluid, have been solved numerically using the finite volume method. The shear stresses were calculated using the Ostwald‐de Waele model for the shear‐thinning nanofluid. The model introduced by Patel et al was used to obtain the thermal conductivity of the nanofluid. The variation of the fluid flow with respect to the Richardson number and volume fraction of the nanoparticles was investigated through a parametric study. Even though increasing the volume fraction of nanoparticles leads to heat transfer enhancement, for the second case of this study, for Ri = 1, the average Nusselt number initially drops sharply by increasing the volume fraction of nanoparticles, then remains constant.     

Performance and emission characteristics of a diesel engine operating on different water in diesel emulsion fuels: optimization using response surface methodology (RSM)

The nitrogen oxide (NO_x) release of diesel engines can be reduced using water in diesel emulsion fuel without any engine modification. In the present paper, different formulations of water in diesel emulsion fuels were prepared by ultrasonic irradiation. The water droplet size in the emulsion, polydisperisty index, and the stability of prepared fuel was examined, experimentally. Afterwards, the performance characteristics and exhaust emission of a single cylinder air-cooled diesel engine were investigated using different water in diesel emulsion fuels. The effect of water content (in the range of 5%–10% by volume), surfactant content (in the range of 0.5%–2% by volume), and hydrophilic-lipophilic balance (HLB) (in the range of 5–8) was examined using Box-Behnken design (BBD) as a subset of response surface methodology (RSM). Considering multi-objective optimization, the best formulation for the emulsion fuel was found to be 5% water, 2% surfactant, and HLB of 6.8. A comparison was made between the best emulsion fuel and the neat diesel fuel for engine performance and emission characteristics. A considerable decrease in the nitrogen oxide emission (–18.24%) was observed for the best emulsion fuel compared to neat diesel fuel.     

Biochemical profiling of Pakistani sorghum and millet varieties with special reference to anthocyanins and condensed tannins

Cereals like sorghum and millet are splendid sources of phenolics, dependent on their genetic makeup, and possess varied levels of flavonoids, flavanols, flavanones, anthocyanins, and condensed tannins. In this study, chemical composition and anthocyanin and tannin content of seven sorghum and two millet varieties were evaluated. American Association of Cereal Chemists (AACC) respective methods were used for chemical composition. Anthocyanins were determined through HPLC/UV-Vis, while condensed tannins were determined spectrophotometrically. Four anthocyanins determined included apigeninidin, kuromanin, pelargonidin, and cyanidin. Among sorghum varieties, JS-263 had the highest apigeninidin (16 µg/g). Other anthocyanins were not found in appreciable quantities. None of the anthocyanins were detected in millet varieties. Condensed tannins were highest in sorghum variety PC-1 (179.76 mg/100g) and millet variety S. Bajra-2011 (172.75 mg/100g). Two varieties, one each from sorghum and millet, were selected for extraction of bran as a separate fraction. Brans were modified by size reduction and enzymatic treatment (xylanase and cellulase). Enzymatic treatment favorably affected the extraction of phenolic compounds like anthocyanins. Sorghum and millet flour- and bran-supplemented breads were also developed and evaluated for sensory acceptability.     

Substrate Integrated Waveguide Cavity Resonators for Complex Permittivity Characterization of Materials

A novel planar substrate integrated waveguide cavity resonator technique for measurement of complex permittivity is described, which has applications for dielectric measurement systems in the pharmaceutical industry. The high-Q resonant structure is a modernization of well-known measurement cells where the dielectric constant is deduced by cavity perturbation from the shift in resonant frequency and the change in the Q factor. The method uses extremely small amounts of a broad range of materials for accurate characterization. The ease of fabrication, low cost, and potential for integration with many other components on the same substrate allows it to be used in a disposable manner.     

Evaluation of colloidal silica suspension as efficient additive for improving physicochemical and in vitro biological properties of calcium sulfate-based nanocomposite bone cement

In the present study new calcium sulfate-based nanocomposite bone cement with improved physicochemical and biological properties was developed. The powder component of the cement consists of 60 wt% α-calcium sulfate hemihydrate and 40 wt% biomimetically synthesized apatite, while the liquid component consists of an aqueous colloidal silica suspension (20 wt%). In this study, the above mentioned powder phase was mixed with distilled water to prepare a calcium sulfate/nanoapatite composite without any additive. Structural properties, setting time, compressive strength, in vitro bioactivity and cellular properties of the cements were investigated by appropriate techniques. From X-ray diffractometer analysis, except gypsum and apatite, no further phases were found in both silica-containing and silica-free cements. The results showed that both setting time and compressive strength of the calcium sulfate/nanoapatite cement improved by using colloidal silica suspension as cement liquid. Meanwhile, the condensed phase produced from the polymerization process of colloidal silica filled the micropores of the microstructure and covered rodlike gypsum crystals and thus controlled cement disintegration in simulated body fluid. Additionally, formation of apatite layer was favored on the surfaces of the new cement while no apatite precipitation was observed for the cement prepared by distilled water. In this study, it was also revealed that the number of viable osteosarcoma cells cultured with extracts of both cements were comparable, while silica-containing cement increased alkaline phosphatase activity of the cells. These results suggest that the developed cement may be a suitable bone filling material after well passing of the corresponding in vivo tests.     

Physico-chemical and in vitro biological evaluation of strontium/calcium silicophosphate glass

Strontium is known to reduce bone resorption and stimulate bone formation. Incorporation of strontium into calcium phosphate bioceramics has been widely reported. In this work, calcium and calcium/strontium silicophosphate glasses were synthesized from the sol–gel process and their rheological, thermal, and in vitro biological properties were studied and compared to each other. The results showed that the gel viscosity and thus the rate of gel formation increased by using strontium in glass composition and by increasing aging temperature. In strontium-containing glass, the crystallization temperature increased and the type of the crystallized phase was different to that of strontium-free glass. Both glasses favored precipitation of calcium phosphate layer when they were soaked in simulated body fluid; however strontium seemed to retard the rate of precipitation slightly. The in vitro biodegradation rate of the strontium/calcium silicophosphate glass was higher than that of strontium-free one. The cell culture experiments carried out using rat calvaria osteoblasts showed that the incorporation of strontium into the glass composition stimulated proliferation of the cells and enhanced their alkaline phosphatase activity, depending on cell culture period.     

On the Relationship of Sample Size and Moments of Estimators in Simple Linear Regression

Methods are developed for determining minimum sample size in simple linear regression (when residuals are nonnormal) that permit use of the classical normality-based analyses. The methods are based on behavior of standardized third and fourth moments of regression estimators. The case of symmetric independent variable values with one observation at each is considered. All other regression assumptions are assumed to be true.     

Expression profile of T cell associated molecules in the interfacial tissue of aseptically loosened prosthetic joints

The involvement of T cells in the progression of inflammation in response to wear debris at the interface of aseptically loosened joints is currently undefined. This cell type has repeatedly been demonstrated to be a common component of the cellular membrane, the interface, which forms between the bone and implant of total joint replacements (TJRs) [1, 2]. Three further insights into the role of this cell type in the interface were investigated here. Immunostaining demonstrated CD4 expression in 80% of the 15 cases tested while CD8 expression was present in 60% of the cases. Polymerase chain reaction (PCR) detected IFN- mRNA expression in 75% of eight cases tested; in contrast IL-10 mRNA was only demonstrated in 50% of these same cases. Proteins extracted from another eight cases of revision tissue were analyzed using Western blotting for IL-17, fractalkine (Fkn) and CD40. IL-17 and Fkn were a consistent feature of all cases tested (8/8), while CD40 was undetectable in one case (7/8). These results show that T cells present in the interface are more commonly of the helper T cell phenotype, although cytotoxic T cells are also present. Helper T cells (Th) are responsible for the polarization of the immune response through their production of key mediators. The PCR results obtained in this study suggest that a Th1 response characterized by the production of IFN- predominates over the Th2, IL-10 mediated response. Furthermore the demonstration of the expression of IL-17, Fkn and CD40, all of which are Th1 associated molecules, supports this conclusion.