Cooperative lattice coding and decoding in half-duplex channels

We propose novel lattice coding/decoding schemes for half-duplex outage-limited cooperative channels. These schemes are inspired by the cooperation protocols of Azarian et al. and enjoy an excellent performance-complexity tradeoff. More specifically, for the. relay channel, we first use our lattice coding framework to generalize Yang and Belfiore implementation of the non-orthogonal amplify and forward cooperation protocol. This generalization is shown to offer significant performance gains while keeping the decoding complexity manageable. We then devise a novel variant of the dynamic decode and forward protocol, along with a lattice-coded implementation, which enjoys a near-optimal diversity-multiplexing tradeoff with a low encoding/decoding complexity. Finally, for the cooperative multiple-access channel, we present a lattice-coded implementation of the non-orthogonal amplify and forward protocol and demonstrate its excellent performance-complexity tradeoff. Throughout the paper, we establish the performance gains of our proposed protocols via a comprehensive simulation study     

BIOSORPTION STUDIES ON NACL-MODIFIED CERATOPHYLLUM DEMERSUM: REMOVAL OF TOXIC CHROMIUM FROM AQUEOUS SOLUTION

The present research provides information on the Cr(VI) removal potential of NaCl-modified Ceratophyllum demersum, an aquatic plant biomass. The effects of various parameters including pH, biomass dosage, contact time, and initial concentration on Cr(VI) biosorption were investigated. The best conditions for Cr(VI) biosorption in the present study were: pH of 2, biosorbent dose of 8 g/L, and contact time of 60 min. Under these conditions, maximum adsorption capacity of modified C. demersum for Cr(VI) was 10.20 mg/g. The experimental biosorption data were modeled by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The biosorption process followed the Langmuir isotherm model with a high coefficient of determination (R² > 0.99). The biosorption process followed pseudo-second-order kinetics. Further, the biosorbent was characterized by Fourier transform-infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The results showed that biosorption of Cr(VI) on NaCl-modified C. demersum occurred through chemical sorption.     

Assessing the performance of an industrial SBCR for Fischer–Tropsch synthesis: Experimental and modeling

The main objective of this study is to predict the performance of an industrial‐scale (ID = 5.8 m) slurry bubble column reactor (SBCR) operating with iron‐based catalyst for Fischer–Tropsch (FT) synthesis, with emphasis on catalyst deactivation. To achieve this objective, a comprehensive reactor model, incorporating the hydrodynamic and mass‐transfer parameters (gas holdup, ε_G, Sauter‐mean diameter of gas bubbles, d₃₂, and volumetric liquid‐side mass‐transfer coefficients, k_La), and FT as well as water gas shift reaction kinetics, was developed. The hydrodynamic and mass‐transfer parameters for He/N₂ gaseous mixtures, as surrogates for H₂/CO, were obtained in an actual molten FT reactor wax produced from the same reactor. The data were measured in a pilot‐scale (0.29 m) SBCR under different pressures (4–31 bar), temperatures (380–500 K), superficial gas velocities (0.1–0.3 m/s), and iron‐based catalyst concentrations (0–45 wt %). The data were modeled and predictive correlations were incorporated into the reactor model. The reactor model was then used to study the effects of catalyst concentration and reactor length‐to‐diameter ratio (L/D) on the water partial pressure, which is mainly responsible for iron catalyst deactivation, the H₂ and CO conversions and the C₅₊ product yields. The modeling results of the industrial SBCR investigated in this study showed that (1) the water partial pressure should be maintained under 3 bars to minimize deactivation of the iron‐based catalyst used; (2) the catalyst concentration has much more impact on the gas holdup and reactor performance than the reactor height; and (3) the reactor should be operated in the kinetically controlled regime with an L/D of 4.48 and a catalyst concentration of 22 wt % to maximize C₅₊ products yield, while minimizing the iron catalyst deactivation. Under such conditions, the H₂ and CO conversions were 49.4% and 69.3%, respectively, and the C₅₊ products yield was 435.6 ton/day. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3838–3857, 2015     

Mechanical and gelling properties of comminuted sausages containing chicken MDM

The present investigation focuses on the physicochemical properties, rheological behaviors and texture of raw and cooked emulsions containing different mechanically deboned meat (MDM) from chicken. MDMs were produced from the neck, backs and thighs. The texture and mechanical profile analyses were performed using a small deformation dynamic oscillation in a shear and instrumental texture analyzer. The mechanical spectra of the raw and cooked MDM emulsion gels were classified as weak gels based on their frequency sweep and tan δ results. Both the G′ and G″ values increased with increasing frequency in the temperature of 4 and 10 °C. The MDM from thighs had the lowest water holding capacity (WHC) and emulsifying (EC) values, while the MDM from backs had significant values of 2.41 and 128.87, respectively. The cooked emulsion containing backs showed the highest hardness and cohesiveness values, while the emulsion containing necks and thighs had the lowest texture parameters.     

Compact reconfigurable triple‐mode triple‐band substrate integrated waveguide bandpass filter

In this study, a reconfigurable triple‐band triple‐mode substrate integrated waveguide filter is designed and fabricated in the C‐band spectrum. A novel and simplified design procedure based on analytical equations is proposed. The filter design also benefits from a reconfigurable structure, using metallic via holes as perturbation, allowing wide‐band selectivity of the C‐band spectrum (from 4.4 to 6.9 GHz). Moreover, the filter benefits from a magnetic coupling solution between the resonators, which only couples the first three modes and rejects the next resonating modes. Therefore, a large bandgap in the spectrum is achieved. The proposed structure is fabricated and measured, and a high similarity between the simulation and fabrication is observed. The measured results show that the first band can be tuned in the frequency range of 4.4 to 7, the second band can be tuned in the range 5.8 to 7.7 GHz, and the third band from 5.8 to 7.7 GHz. The insertion loss 1.5 to 2.5 dB, 2 to 3 dB, and 2.5 to 3.5 dB for the first, second, and third bands, respectively.     

Controlled synthesis and photocatalytic activities of barium hexaferrite nanoparticles and examine decolorization methyl orange on liver of rats

The controlled morphological of magnetic nanoparticles have gained great importance in a wide variety of applications due to their promising physico-chemical properties. Therefore, in this study, barium hexaferrite (BaFe₁₂O₁₉) nanoparticles were prepared with the simplest and most efficient chemical route, the two-step sol–gel method, in the presence of seven different and widely used surfactants. The aim of this research is to investigate the influence of the different surfactants on the morphology and particle size of the BaFe₁₂O₁₉ nanoparticles; therefore, different techniques were employed in order to elucidate the composition and structure of the BaFe₁₂O₁₉ nanoparticles such as XRD, SEM, FT-IR, and EDX. The magnetic properties were investigated by measuring the hysteresis loops. In order to investigate the role of BaFe₁₂O₁₉ nanoparticles as the photocatalysts, decolorization of methyl orange under ultraviolet light irradiation was also evaluated. In addition, the purity of decolorized water was examined by investigating its effect on the health condition of liver of rats.     

Analysis of biofilm growth in the presence of osmotic pressure and temperature effects

Transient mass transfer in a diffusion–reaction biofilm with a moving boundary was investigated analytically. The analysis incorporates both the diffusion processes into the biofilm as well as the reaction processes that lead to the expansion of the system. For first and second order reaction terms, the biofilm synthesis as a function of time was presented. The temporal development of the biomass was found to be in very good agreement with numerical results. The effects of osmotic pressure and temperature were also investigated and it was found that osmotic pressure plays a significant role in first order reactions but the temperature dependence is primarily found in the reaction kinetics and does not significantly influence osmotic pressure effects.     

Structural investigation and response surface optimisation for improvement of kefiran production yield from a low-cost culture medium

Kefiran, a water-soluble heteropolysaccharide with molecular weight of 1.35 × 10⁶ Da and a specific optical rotation of +64° (c 1.0, H₂O), was isolated from kefir grains grown in cheese whey and further purified through DEAE-Sepharose XK26. Response surface methodology was employed to optimise the culture conditions for kefiran production from kefir grains to be lactose concentration 67 g/l, yeast extract 13 g/l, pH 5.7 and temperature 24 °C. Intrinsic viscosity was 5.84 dl/g using the Huggins extrapolation and 5.53 dl/g using the Kramer extrapolation. Monosaccharide analysis revealed that kefiran is composed of glucose (Glc) and galactose (Gal) in a relative molar ratio of 1.0:1.1. Its structural features were elucidated by a combination of FT-IR, methylation and GC–MS analysis, periodate oxidation–Smith degradation, partial acid hydrolysis and NMR spectroscopy (¹H, ¹³C and HMBC). The data obtained indicated that kefiran possessed a backbone of (1 → 6)-linked Glc, (1 → 3)-linked Gal, (1 → 4)-linked Gal, (1 → 4)-linked Glc and (1 → 2,6)-linked Gal, with a branch attached to O-2 of Gal residues and terminated with Glc residues.     

A statistical approach to the optimization of cold‐adapted amylase production by Exiguobacterium sp. SH3

Cold‐adapted enzymes produced by psychrotrophic organisms are interesting from both molecular and biotechnological viewpoints. The enzymes show superior catalytic activity than their mesophilic and thermophilic counterparts at room temperature. Therefore, the enzymes seem interesting for applications where high catalytic activity at ambient temperature is required. In this study, the production of cold‐adapted amylase by Exiguobacterium sp. SH3 was optimized and modeled. In the first step, single factor experiments using shake flask cultures were conducted for primary optimization. These experiments resulted in the improvement of amylase production up to 180 U/mL. In the next step, the Plackett–Burman design was used to identify significant factors affecting the amylase production. Starch concentration, tryptone concentration, and temperature were selected as significant factors; while time, shaking, yeast extract, pH, MnCl₂, CaCl₂, MgCl₂, and KH₂PO₄ were not significant in this step. Finally, the response surface methodology based on central composite design (CCD) was used for further optimization and modeling of the significant factors. The optimization efforts resulted in the maximum amylase production of 730 U/mL, which was four times higher than that achieved by the single‐factor optimization experiments.