All ambient environment‐based perovskite film fabrication for photovoltaic applications

Low‐temperature solution process‐able perovskite solar cells are highly desirable for future photovoltaics. Chemical root was utilized to synthesize and optimize mixed halide‐based MAPbIBr₂ light absorber perovskites on electron transport layer of TiO₂ nanoparticles in ambient atmosphere. For the first time all synthesis work was performed in an ambient environment and observe material behavioral characteristics. To accurately control the film morphology, one‐step deposition technique was applied to investigate material's optoelectronic behavior. The role of the perovskite structure, physical, and optical properties in planner device architecture was studied through ultraviolet visible, X‐ray diffraction, X‐ray photoelectron spectroscopy, and scanning electron microscope characterization techniques to confirm a band gap of 1.76 eV with cubic crystalline structure having a particle size of 12.5–13.0 nm, which is highly suitable for perovskite solar cells.     

Numerical simulation of dispersion in urban street canyons with avenue-like tree plantings: Comparison between RANS and LES

Previous CFD studies on pollution dispersion problems have largely centred on employing Reynolds-averaged Navier–Stokes (RANS) turbulence closure schemes, which have often been reported to overpredict pollutant concentration levels in comparison to wind tunnel measurement data. In addition, the majority of experimental and numerical investigations have failed to account for the aerodynamic effects of trees, which can occupy a significant proportion of typical urban street canyons. In the present work, the prediction accuracy of pollutant dispersion within urban street canyons of width to height ratio, W/H = 1 lined with avenue-like tree plantings are examined using two steady-state RANS models (the standard k-ε and RSM), and Large Eddy Simulation (LES) to compare their performance against wind tunnel experiments available on the online database CODASC [1]. Two cases of tree crown porosities are investigated, one for a loosely (P_vol = 97.5%) and another for a densely (P_vol = 96%) packed tree crown, corresponding to pressure loss coefficients of λ = 80 m⁻¹ and λ = 200 m⁻¹, respectively. Results of the tree-lined cases are then compared to a tree-free street canyon in order to demonstrate the impact of trees on the flow field and pollutant dispersion, and it is observed that the presence of trees reduces the in-canyon circulation and air exchange, and increases the overall concentration levels. Between the two numerical methods employed, LES performs better than RANS, because it captures the unsteady and intermittent fluctuations of the flow field, and hence, successfully resolves the transient mixing process within the canyons.     

Numerical simulation of atmospheric pollutant dispersion in an urban street canyon: Comparison between RANS and LES

Prediction accuracy of pollutant dispersion within an urban street canyon of width to height ratio W/H=1 is examined using two steady-state Reynolds-averaged Navier–Stokes (RANS) turbulence closure models, the standard k–ε and Reynolds Stress Model (RSM), and Large Eddy Simulation (LES) coupled with the advection–diffusion method for species transport. The numerical results, which include the statistical properties of pollutant dispersion, e.g. mean concentration distributions, time-evolution and three-dimensional spreads of the pollutant, are then compared to wind-tunnel (WT) measurements. The accuracy and computational cost of both numerical approaches are evaluated. The time-evolution of the pollutant concentration (for LES only) and the mean (time-averaged) values are presented. It is observed that amongst the two RANS models, RSM performed better than standard k–ε except at the centerline of the canyon walls. However, LES, although computationally more expensive, did better than RANS in predicting the concentration distribution because it was able to capture the unsteady and intermittent fluctuations of the flow field, and hence resolve the transient mixing process within the street canyon.     

Some flavouring constituents of cassava and of processed cassava products

Flavouring constituents of cassava, gari and farine were analysed and compared. The characteristic compounds of gari were identified as pyrazines and lactic acid. Farine, which is either unfermented or fermented for a much shorter time than gari, was qualitatively similar but had fewer volatiles, present in small amounts. Pyrazines and lactic acid were absent from cassava, the flavouring constituents of which were fewer and qualitatively different from those of gari and farine. The characteristic flavour of gari and farine was largely due to the fermentation and roasting processes.     

Isolation and characterization of lecithin from squid (Todarodes pacificus) viscera deoiled by supercritical carbon dioxide extraction

Marine lecithin was isolated and characterized from squid (Todarodes pacificus) viscera residues deoiled by supercritical carbon dioxide (SC-CO(2)) extraction. SC-CO(2) extraction was carried out to extract the oil from squid viscera at different temperatures (35 to 45 °C) and pressures (15 to 25 MPa). The extraction yield was higher at highest temperature and pressure. The major phospholipids of squid viscera lecithin were quantified by high-performance liquid chromatography (HPLC). Phosphatidylcholine (PC; 80.5% ± 0.7%) and phosphatidylethanolamine (PE; 13.2% ± 0.2%) were the main phospholipids. Thin layer chromatography (TLC) was performed to purify the individual phospholipids. The fatty acid compositions of lecithin, PC and PE were analyzed by gas chromatography (GC). A significant amount of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were present in both phospholipids of PC and PE. Emulsions of lecithin in water were prepared through the use of a homogenizer. The oxidative stability of squid viscera lecithin was high in spite of its high concentration of long-chain polyunsaturated fatty acids. PRACTICAL APPLICATION: Squid viscera are discarded as a waste by fish processing industry. Since lecithin from squid viscera contains higher amounts of polyunsaturated fatty acids, it may have promising effect to use in food, pharmaceutical, and cosmetic industries.     

Antioxidant activities of some dried fruits consumed in Algeria

Dried fruits such as prune, apricots, raisins and figs are an important source of different antioxidants which can inhibit the harmful effects of the free radicals. They receive increasing attention for their potential role in prevention of human diseases. The aims of our study were the quantification of some antioxidants (carotenoïds, total phenolic compounds, anthocyanins, flavonoïds and proanthocyanidins) using colorimetric assays and the determination of antioxidant activities by three methods. Three aqueous solvents (distilled water, ethanol and methanol) were used for the extraction of some antioxidants. Apricots and figs had the highest concentration of carotenoïds (10.7 and 10.8 mg βCE/100 g, respectively). Raisins were the richest fruits in total phenolic concentration (1.18 g GAE/100 g) and proanthocyanidins (17.53 mg CE/100 g). Also, figs had the highest concentration of flavonoïds (105.6 mg QE/100 g) and anthocyanins (5.9 mg/100 g). Apricots and raisins possessed a good reducing power, while Agen prune showed significant antioxidant activity to the phosphomolybdate. There were significant correlations between total phenolic concentration and antiradical activity (r = 0.89; p < 0.001) of ethanolic extract and reducing power (r = 0.80; p < 0.01) of aqueous extract.     

Methods for PDO olive oils traceability: state of art and discussion about the possible contribution of strontium isotopic tool

Olive oil represents an important ingredient in the Mediterranean diet and is appreciated both for nutritional and sensory properties, often related to geographical origin and cultivar of olive fruits employed. Fraudsters trying to seek financial gain can adulterate the product causing economic repercussions and, sometimes sanitary risks. The “protected designation of origin” (PDO) label insures a relative protection of both consumers and honest producers, since it prescribes production techniques and specific geographical origin, but one of the main problems is to set down objective tools to control these specifications. We reviewed numerous studies using various analytical tools to discriminate PDO olive oils’ geographical origin depending on (1) volatiles compounds, (2) fatty acid and triacylglycerol composition, (3) trace elements, and/or (4) stable isotope ratios, but we highlighted that, despite their efficiency, none of them could provide an irrefutable identification. However, ⁸⁷Sr/⁸⁶Sr signature revealed to be an optimal geographical fingerprint in the same purpose for other food products like cereals, orange juice, coffee or alcoholic beverages. Such ⁸⁷Sr/⁸⁶Sr studies do not exist on olive oils, probably because of analytical issues, but we propose that developing complementary ⁸⁷Sr/⁸⁶Sr studies could be a promising tool to re-enforce the characterization of PDO olive oils.     

Differential modulation for asynchronous two‐way relay systems over frequency‐selective fading channels

We propose two schemes for asynchronous multi‐relay two‐way relay (MR‐TWR) systems in which neither the users nor the relays know the channel state information. In an MR‐TWR system, two users exchange their messages with the help of N_R relays. Most of the existing works on MR‐TWR systems based on differential modulation assume perfect symbol‐level synchronization between all communicating nodes. However, this assumption is not valid in many practical systems, which makes the design of differentially modulated schemes more challenging. Therefore, we design differential modulation schemes that can tolerate timing misalignment under frequency‐selective fading. We investigate the performance of the proposed schemes in terms of either probability of bit error or pairwise error probability. Through numerical examples, we show that the proposed schemes outperform existing competing solutions in the literature, especially for high signal‐to‐noise ratio values. Copyright © 2016 John Wiley & Sons, Ltd.