Effects of fibers and nanoparticles reinforcements on the mechanical and biological properties of hybrid composite polyetheretherketone/short carbon fiber/Nano‐SiO2

Polyetheretherketone (PEEK) composites reinforced with short carbon fibers (SCFs) (20 vol%) and nano‐SiO₂ (1, 1.5, and 2 wt%) particles were prepared by incorporating nanoparticles into PEEK/SCF composites using the internal mixer. In the development of biomaterial, both mechanical and biological characteristics must be considered. Thus, the effects of nanoparticles on the mechanical and biological properties of the PEEK/SCF composites were studied. To evaluate the mechanical properties of this biomaterial, nanoindentation method and tensile test were used. Results showed that by increasing the weight percentage of nano‐SiO₂, the elastic modulus, hardness, and tensile energies were increased. In vitro biological evaluations of the samples were done by performing cytotoxicity (3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐iphenyltetrazolium bromide assay) and cell adhesion assays. Cell–material interaction with the surface of the composite was examined by scanning electron microscopy (SEM). In all of the tests, osteoblast cells were used. Results of biological tests showed that the samples are biocompatible and they have no toxicity. Also, Adhered cells presented a normal morphology by SEM and many of the cells were observed to be undergoing cell division. POLYM. COMPOS., 34:1960–1968, 2013. © 2013 Society of Plastics Engineers     

The ITZ microstructure,thickness, porosity and its relation with compressive and flexural strength of cement mortar; influence of cement fineness and water/cement ratio

A new insight into the interfacial transition zone (ITZ) in cement mortar specimens (CMSs) that is influenced by cement fineness is reported. The importance of cement fineness in ITZ characterizations such as morphology and thickness is elucidated by backscattered electron images and by consequences to the compressive (F_c) and flexural strength (F_f), and porosity at various water/cement ratios. The findings indicate that by increasing the cement fineness the calcium silicate hydrate formation in the ITZ is favored and that this can refine the pore structures and create a denser and more homogeneous microstructure. By increasing cement fineness by about 25% of, the ITZ thickness of CMSs was reduced by about 30% and F_c was increased by 7%–52% and F_f by 19%–40%. These findings illustrate that the influence of ITZ features on the mechanical strength of CMSs is mostly related to the cement fineness and ITZ microstructure.     

Evaluation of pre-rigor injection of beef with proteases on cooked meat volatile profile after 1day and 21days post-mortem storage

This research was carried out to determine the effects of pre-rigor injection of beef semimembranosus muscle with nine proteases from plant and microbial sources, on the volatile profile of cooked beef after 1 day and 21 days post-mortem (PM) storage using Solid-phase microextraction gas chromatography mass spectrometry analysis. A total of 23 aldehydes, 5 ketones, 3 furans, 8 nitrogen and sulphur compounds, 4 alkanes, 7 alcohols and 6 terpenes were detected. Eleven volatile compounds characteristic of ginger flavour were detected in zingibain-treated meat. Benzaldehyde significantly increased (p<0.05) only in kiwifruit juice (KJ), fungal 31 protease and Asparagus protease (ASP) treated samples from 1day to 21days PM storage. A significant increase (p<0.05) in 3-methylbutanal was observed in KJ, bacterial and fungal protease treated samples at 21days PM storage. Treatments with bromelain, papain, ASP, actinidin, and KJ (except KJ 21days) proteases resulted in flavour profiles closer to that of the control beef sample.     

Analysis of pork adulteration in commercial meatballs targeting porcine-specific mitochondrial cytochrome b gene by TaqMan probe real-time polymerase chain reaction

A test for assessing pork adulteration in meatballs, using TaqMan probe real-time polymerase chain reaction, was developed. The assay combined porcine-specific primers and TaqMan probe for the detection of a 109 bp fragment of porcine cytochrome b gene. Specificity test with 10 ng DNA of eleven different species yielded a threshold cycle (Ct) of 15.5 ± 0.20 for the pork and negative results for the others. Analysis of beef meatballs with spiked pork showed the assay can determine 100-0.01% contaminated pork with 102% PCR efficiency, high linear regression (r(2) = 0.994) and ≤ 6% relative errors. Residuals analysis revealed a high precision in all determinations. Random analysis of commercial meatballs from pork, beef, chicken, mutton and goat, yielded a Ct between 15.89 ± 0.16 and 16.37 ± 0.22 from pork meatballs and negative results from the others, showing the suitability of the assay to determine pork in commercial meatballs with a high accuracy and precision.     

Nonlinear Propagation of Ion-Acoustic Shock waves in Dissipative Electron–Positron–Ion Plasmas with Superthermal Electrons and Relativistic Ions

A weakly nonlinear analysis is carried out to derive the appropriate Korteweg–de Vries–Burgers-like equation for small, but finite amplitude, ion-acoustic waves in a dissipative plasma consisting of relativistic ions, Maxwell–Boltzmann distributed positrons and superthermal electrons. Our results show that in a such plasma, ion-acoustic shock waves, the spatial patterns of which are significantly modified by the relativistic and dissipative effects, may exist. Interestingly, we found that because of ion kinematic viscosity, an initial solitonic profile develops into a shock wave. This later evolves towards a monotonic profile (dissipation–dominant case) as the electrons deviate from their thermodynamic equilibrium. As the relativistic character of the plasma becomes important, the shock wave amplitude decreases. Our investigation may be taken as a prerequisite for the understanding of the shock-waves observed in the ionosphere and the auroral acceleration regions. We recall that when a high energy cosmic ray interacts with the earth’s atmosphere, it may produce an electron–positron pair with enormous velocities. The data obtained during the Alpha Magnetic Spectrometer (AMS) flight permitting to probe the radiation belts in the Earth’s innermost magnetosphere provided an evidence of the presence of positrons.     

Cryptanalysis of mCrypton—A lightweight block cipher for security of RFID tags and sensors

mCrypton is a 64‐bit lightweight block cipher designed for use in low‐cost and resource‐constrained applications such as RFID tags and sensors in wireless sensor networks. In this paper, we investigate the strength of this cipher against related‐key impossible differential cryptanalysis. First, we construct two 6‐round related‐key impossible differentials for mCrypton‐96 and mCrypton‐128. Then, using these distinguishers, we present 9‐round related‐key impossible differential attacks on these two versions. The attack on mCrypton‐96 requires 2^59.9 chosen plaintexts, and has a time complexity of about 2^74.9 encryptions. The data and time complexities for the attack on mCrypton‐128 are 2^59.7 chosen plaintexts and 2^66.7 encryptions, respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

The production of biohydrogen by a novel strain Clostridium sp. YM1 in dark fermentation process

In view of increasing attempts for the production of renewable energy, the production of biohydrogen energy by a new mesophilic bacterium Clostridium sp. YM1 was performed for the first time in the dark fermentation. Experimental results showed that the fermentative hydrogen was successfully produced by Clostridium sp. YM1 with the highest cumulative hydrogen volume of 3821 ml/L with a hydrogen yield of 1.7 mol H₂/mol glucose consumed. Similar results revealed that optimum incubation temperature and pH value of culture medium were 37 °C and 6.5, respectively. The study of hydrogen production from glucose and xylose revealed that this strain was able to generate higher hydrogen from glucose compared to that from xylose. The profile of volatile fatty acids produced showed that hydrogen generation by Clostridium sp. YM1 was butyrate-type fermentation. Moreover, the findings of this study indicated that an increase in head space of fermentation culture positively enhanced hydrogen production.     

Experimental study of argon dilution effects on NO x emission in a non-premixed flame in comparison with nitrogen

The effects of nitrogen and argon dilution on NO _X emission of turbulent propane-air non-premixed flame in a furnace are experimentally investigated. Dilution is an effective process in reducing NO _X emission, since diluents cause an increase in the mass flow of the fuel, and consequently the temperature in the combustion chamber and NO _X emission decreases. We measured NO _X emission and temperature for a wide range of dilution and equivalence ratios. The results show that nitrogen dilution is more effective than argon dilution in reducing NO _X emission. In addition, both dilutions caused the yellow color of the non-premixed flame to turn blue, which indicates more complete combustion and better mixing of fuel and oxidant.     

Preparation and Characterization of PAn-HPC/Fe3O4 and PAn-HPC/Fe2O3 Nanocomposite Using Hydroxypropylcellulose as a Steric Stabilizer

Nanocomposite of polyaniline containing Fe₃O₄ and Fe₂O₃ was synthesized by a chemical method using hydroxypropylcellulose as a steric stabilizer. The characteristics of product such as, morphology, conductivity, and particle size were studied. The results indicate that, these properties were dependent on the surfactant, amount and type of metallic oxide. When the concentration of Fe₂O₃ and Fe₃O₄ increased from 1 to 5 g/L, in PAn/Fe₂O₃ and PAn/Fe₃O₄ composites the conductivity decreased from 1.2 × 10^?6 to 1.1 × 10^?8 and 2.8 × 10^?6 to 1.1 × 10^?8S/cm, respectively, while the particle size of nanocomposite increased from 96 to 110, and 97 to 115 nm, respectively.