Antioxidant and antibacterial effects of Lavandula and Mentha essential oils in minced beef inoculated with E. coli O157:H7 and S. aureus during storage at abuse refrigeration temperature

The essential oils (EOs) of Lavandula angustifolia L. and Mentha piperita L. were analyzed by gas chromatography mass spectrometry (GC/MS). The major constituents were linalool (22.35%), linalyl acetate (21.80%), trans-ocimene (6.16%) and 4-terpineol (5.19%) for L. angustifolia and menthol (33.28%), menthone (22.03%), and menthyl acetate (6.40%) for M. piperita. In vitro antibacterial activity of both EOs against Escherichia coli O157:H7 and Staphylococcus aureus CECT 4459 showed high inhibition against S. aureus. The lowest minimal inhibitory concentrations (MIC) were obtained with L. angustifolia (0.25μL/mL) against S. aureus; M. piperita exhibited a MIC of 0.50μL/mL against both microorganisms. Both EOs caused a significant decrease of bacterial growth in minced beef (p<0.05) stored at 9±1°C. Minced beef treated with EOs showed the lowest TBARS values (lipid oxidation). Moreover, the results showed that the addition of EOs significantly extended fresh meat odor even at abuse temperature.     

Fault diagnosis of rotary kiln using SVM and binary ACO

This paper proposes a novel hybrid algorithm for fault diagnosis of rotary kiln based on a binary ant colony (BACO) and support vector machine (SVM). The algorithm can find a subset selection which is attained through the elimination of the features that produce noise or are strictly correlated with other already selected features. The BACO algorithm can improve classification accuracy with an appropriate feature subset and optimal parameters of SVM. The proposed algorithm is easily implemented and because of use of a simple filter in that, its computational complexity is very low. The performance of the proposed algorithm is evaluated through two real Rotary Cement kiln datasets. The results show that our algorithm outperforms existing algorithms.     

Study of the miscibility of poly(ethyl methacrylate-co-4-vinylpyridine)/poly(styrene-co-cinnamic acid) blends

Summary The miscibility of a series of poly(ethyl methacrylate-co-4-vinylpyridine) with poly(styrene-co-cinnamic acid), is investigated by differential scanning calorimetry. The results show that each blend is miscible as ascertained by a single composition dependent glass transition temperature. The Tg's of the blends exhibit positive deviations from the weight average Tg's of the blend components. The thermograms data exploited according to the Kwei and Schneider approaches suggest the occurrence of strong specific intermolecular attractive interactions within the binary systems. The strength of these interactions, as estimated from the Kwei q-values, increases with the proton donor and proton acceptor contents in the copolymers. Received: 23 January 1999/Revised version: 29 April 1999/Accepted: 1 June 1999     

Computing Shear Flow and Sludge Blanket in Secondary Clarifiers

Recent developments in computing turbulent and buoyant flow in sedimentation tanks are introduced. The test case is a circular, center-feed secondary clarifier with inclined bottom and central sludge withdrawal. Axisymmetry is assumed, and the flow and settling processes are modeled in a radial section by using the k-ε turbulence model on a two-dimensional, nonorthogonal grid. The computation domain includes the sludge blanket where the viscosity is affected by the rheological behavior of the sludge. The aim of the present study is to evaluate the sensitivity of the flow and concentration fields to parameters that characterize (1) the rheological properties of highly concentrated regions; (2) the settling of sludge; and (3) the effect of stratification on the turbulent diffusion. The overall appearance of the fields proves to be similar, whereas the regions of high velocities and high gradients are strongly affected by using different parameters or approaches on rheology, settling, and diffusive transport, resulting in different sludge blanket heights.     

Numerical analysis of earth air heat exchangers at operating conditions in arid climates

This paper presents the modeling and simulation of an earth air heat exchanger (EAHE), employed as an air-conditioning device for buildings in the climate conditions of the south of Algeria. The earth tubes buried in the ground can offer considerable advantages in terms of energy savings. The appropriate depth of the buried tubes was calculated taking into account the physical properties of the soil in the region under study and using a specific program developed by the authors. A parametric analysis was carried out taking into account the length and the radius of the pipe and the velocity of the air in the pipe. The results of performance and overall energy savings are presented. The maximum daily cooling capacity of the EAHE studied was 1.755 kWh. Results showed that a simple EAHE system can provide 246.815 kWh in a period of one year.     

Green emitting β$\ubeta$-SiAlON:Eu2+ phosphors derived from chemically modified perhydropolysilazanes

We report the first synthesis of β-SiAlON:Eu²⁺ phosphors from single-source precursors, perhydropolysilazane (PHPS), chemically modified with Al(OCH(CH₃)₂)₃, and EuCl₂. The reactions occurring during the precursor synthesis and the subsequent thermal conversion of polymeric precursors into β-SiAlON:Eu²⁺ phosphors have been studied by a complementary set of analytical techniques, including infrared spectroscopy, gas chromatography–mass spectrometry, thermogravimetry–mass spectrometry, X-ray diffraction (XRD), photoluminescence spectroscopy, and scanning electron microscopy. It has been clearly established that Al(OCH(CH₃)₂)₃ immediately reacted with PHPS to afford N–Al bonds at room temperature, whereas N–Eu bond formation was suggested to proceed above 600°C accompanied by the elimination of HCl up to 1000°C in flowing N₂. The subsequent 1800°C-heat treatment for 1 h under an N₂ gas pressure at 980 kPa allowed converting the single-source precursors into fine-grained β-SiAlON:Eu²⁺ phosphors. XRD analysis revealed that the Al/Si of .09 was the critical atomic ratio in the precursor synthesis to afford single-phase β-SiAlON (z = .55). Moreover, Eu²⁺-doping was found to efficiently reduce the carbon impurity in the host β-SiAlON. The polymer-derived β-SiAlON:Eu²⁺ phosphors exhibited green emission under excitation at 460 nm and achieved the highest green emission intensity at the critical dopant Eu²⁺ concentration at 1.48 at%.     

Miniaturized six-ring elliptical monopole-based MIMO antenna for ultrawideband applications

This paper proposes a miniature two-element Multiple Input Multiple Output (MIMO) antenna dedicated to UWB applications. The proposed MIMO design has a very low profile of 30 × 20 × 1.6 mm³. The proposed antenna is carefully designed and optimized using HFSS simulation software. As a proof of concept, the proposed design is realized and experimentally tested for MIMO applications. The proposed structure, printed on an FR4 substrate, comprises two symmetrical elliptical conductive patches on the upper side and a modified ground plane on the lower one. Each radiating element includes six elliptical rings. The modified ground plane consists of a T-shaped strip and two semielliptical slots etched opposite the feed line. All the parameters of the design are carefully optimized to achieve an ultrawide bandwidth antenna spanning from (136.08%) 3.1 to 16.3 GHz. The results are discussed and analyzed in terms of bandwidth, gain, efficiency, radiation pattern, diversity gain, envelope correlation coefficient (ECC), total active reflection coefficient (TARC), and mean effective gain (MEG). All simulated results are found to be in good accordance with experiments. The design reveals attractive features for UWB applications. A good isolation (17 dB) between the two radiators is achieved despite the close proximity using the suggested ground plane geometry.     

Chitosan nanoparticles with controlled size and zeta potential

Optimization of chitosan nanoparticles (ChNs) production process employing a 2^(5–2) fractional factorial design was performed to analyze the influence of viscosity average molecular weight (40–120 kDa), the initial concentration of chitosan (2–5 g/L), the initial tripolyphosphate (TPP) concentration (0.8–1.2 g/L), the ratio chitosan/TPP (4/1–10/1) (V/V), and the stirring speed (300–700 rpm), on final nanoparticles size and zeta potential. The measured responses of average particle size and surface charge were determined on Zetasizer Nano ZS. ChNs were prepared using ionotropic cross-linking of chitosan and TPP and were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and differential scanning calorimetry (DSC). The experiments showed that the size of synthesized nanoparticles depended on initial concentration and molecular weight of chitosan, TPP concentration and stirring speed within the chosen levels. However, the zeta potential was significantly influenced by chitosan molecular weight, chitosan concentration and stirring speed. The FTIR analysis confirmed the interaction between negative charge of TPP with positive charge of chitosan through the appearance of new peaks at 1222 and 895 cm⁻¹ in produced ChNs. XRD and DSC analysis were used to evaluate the effect of crosslinking of chitosan on crystal structure of ChNs.     

Photoelectrochemical,optical and magnetic properties of magnetite nanoparticles

Magnetite magnetic nanoparticles are prepared using olive leaf extract as a green reducing and stabilizing agents. After reaction the product is heated up to get rid of the organic compounds and get pure magnetite nanoparticles. Differential scanning calorimetry is used to study the phase transformation as a function of heating temperature. Scanning electron microscope and high resolution transmission electron microscope show spherical and crystallized nanoparticles with a size of 5 nm. X-ray diffraction and Raman and x-ray photoelectron spectroscopy indicate the formation of Magnetite phase with high cristallinity and purity. The synthesized Magnetite nanoparticles are semiconductors with gap energy around 2 eV. Observed by transmission electron microscope graphite rods with stacked carbon disks are decorated with the prepared nanoparticles and show enhanced photocurrent. The vibrating sample magnetometer measurements indicate that the prepared Magnetite nanoparticles have superparamagnetic behavior. These results are very promising for clinical and water splitting applications.