Liquid chromatographic–mass spectrometric analysis of glycerophospholipids in corn oil

The phospholipid composition of corn oil was determined by LC/ESI-MS. The content of phospholipids in the oils varied from 5.2% to 8.7%. The major components in the phospholipids fraction were phosphatidylcholine (57.5–68.1%), phosphatidylinositol (14.5–19.8%), and phosphatidylethanolamine (10.3–13.9%). Phosphatidic acid and phosphatidylglycerol accounted for less than 10% of total phospholipid content. Various molecular species within each class were detected. The phosphatidylcholine class was mainly composed of phosphatidylcholine-C18:2/C18:1 (40–45%) and phosphatidylcholine-18:1/C18:1 (40–51%). Phosphatidylinositol-C16:0/C18:2 (50–69%) was the most abundant phosphatidylinositol. The two phosphatidylethanolamines were phosphatidylethanolamine-C16:0/C18:2 (34–42%) and phosphatidylethanolamine-C18:2/C18:2 (31–36%). Phosphatidylglycerol species were mainly phosphatidylglycerol-C16:0/C18:2 (42–48%) and phosphatidylglycerol-C16:0/C18:1 (36.7–40.3%). Identification of PC molecular species suggests the possibility that corn oil can have therapeutics effects.     

Statistical distribution of the convergence time of evolutionaryalgorithms for long-path problems

The behavior of a (1+1)-ES process on Rudolph's binary long k paths is investigated extensively in the asymptotic framework with respect to string length l. First, the case of k=l^α is addressed. For α⩾1/2, we prove that the long k path is a long path for the (1+1)-ES in the sense that the process follows the entire path with no shortcuts, resulting in an exponential expected convergence time. For α<1/2, the expected convergence time is also exponential, but some shortcuts occur in the meantime that speed up the process. Next, in the case of constant k, the statistical distribution of convergence time is calculated, and the influence of population size is investigated for different (μ+λ)-ES. The histogram of the first hitting time of the solution shows an anomalous peak close to zero, which corresponds to an exceptional set of events that speed up the expected convergence time with a factor of l². A direct consequence of this exceptional set is that performing independent (1+1)-ES processes proves to be more advantageous than any population-based (μ+λ)-ES     

Composition of peel essential oils from four selected Tunisian Citrus species: Evidence for the genotypic influence

The peel essential oils from four selected Tunisian Citrus species: sweet orange (Citrus sinensis Osbeck), mandarin (Citrus reticulata Blanco); sour orange (Citrus aurantium L.) and pummelo (Citrus grandis Osbeck), cultivated under the same pedoclimatic and cultural conditions have been analysed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). The essential oils content ranged from 1.06% to 4.62% (w/w) in pummelo and mandarin, respectively. The qualitative and quantitative analysis led to the identification of 70 components in all oil samples. The analysed oils consist mainly in monoterpene hydrocarbons (97.59–99.3%), with limonene (92.52–97.3%) and β-pinene (1.37–1.82) being the major constituents. The remaining chemical classes were weakly represented (<1%). Both qualitative and quantitative differences between oil samples have been observed and numerous components have been proposed as marker compounds. Since the influence of different environmental factors has been eliminated, the observed chemical variability between the studied species and cultivars seems likely to results from the genetic variability.     

α-Tocopherol and fatty acids contents of some Tunisian table olives (Olea europea L.): Changes in their composition during ripening and processing

An experimental investigation was carried out on Tunisian olive-fruits of Meski, Sayali and Picholine cultivars. α-Tocopherol and fatty acids (FA) contents were analyzed, during both ripening and processing, according to the Spanish style. The relationship between oil, unsaponifiable and α-tocopherol contents was determined only during ripening. A genetic effect on FA composition was observed throughout the sampling periods. The highest oleic acid content was found in Sayali cultivar at green stage (78.5% of total FA). α-Tocopherol was positively correlated with unsaturated FA content (R = 0.71, p < 0.05), and oil amount (R = 0.984; R = 0.976; R = 0.952, p < 0.05 for Picholine, Sayali and Meski, respectively), but it was not correlated with unsaponifiable matter. In processed olive-fruits, the results showed primarily, that processing according to the Spanish style is not restricted to green olive-fruits but can be successfully used in cherry olives with guaranteed quality and nutritional value of processed product (Meski and Picholine) related to FA content. Secondly, both α-tocopherol and FA amounts decreased during processing for all cultivars. This decrease was cultivar dependent. It was more pronounced in the black fruit than in the green one for the same cultivar. During fermentation, pH variation showed the same profile in all cultivars. Final pH values at the end of fermentation depend on the concentration of free FA (acidity) in the brine.     

Insights into the use of landfill leachate to grow Chlorella sp. for lipid and fatty acids production

Clean Technologies and Environmental Policy - Microalgae provide a potential alternative for high-value products. Integrating microalgae into the landfill leachate valorization process gives the...     

Canopy bidirectional reflectance calculation based on Adding method and SAIL formalism: AddingS/AddingSD

The SAIL model (proposed by Verhoef) is largely used in the remote sensing community to calculate the canopy Bidirectional Reflectance Distribution Function. The simulation results appear acceptable compared to observations especially for not very dense planophile vegetation. However, for erectophile dense crops (e.g. corn) the simulations appear less accurate. This inadequacy is due to the assumption that the multiple scattered fluxes are isotropically distributed. The SAIL parameters are interpretable at the level of elementary layer components. Now, the Adding method (initially proposed by Van de Hulst) provides a good framework to model the radiative transfer inside a vegetation layer, but its parameter estimation lies on very simple geometric modeling of the canopy. In this paper, we first propose an adaptation of the Adding method using the SAIL model canopy representation in the turbid case: it is called AddingS model. Such an approach allows to overcome the isotropy assumption. Second, AddingS is extended to the Discrete case: defining the AddingSDmodel. It allows to take into account the multi hot spot effect. Moreover, the AddingS and AddingSD models allow to check the energy conservation in respectively turbid and discrete cases. Finally, in order to keep reasonable time performance, a fast computation method was developed.     

Efficient stop-and-wait type II hybrid ARQ scheme

An efficient stop-and-wait ARQ protocol proposed by Sastry (1975) is modified to include a parity retransmission type II hybrid ARQ scheme. Unlike the Sastry scheme in which simple repeats of a data packet are transmitted, with the type II hybrid ARQ scheme, the data packet to be transmitted is encoded with a rate 1/2 code, and repetitions alternate between the two sequences obtained at the output of the encoder. It is found that the throughput can be substantially increased.<>     

An Adaptive Hybrid ARQ Scheme

A hybrid ARQ in which the transmitter adaptively selects an FEC code according to the channel condition is presented and analyzed. The code is selected according to the past transmissions and acknowledgements by an algorithm which is a generalization of that in [1]. The throughput is obtained as a function of the frame error rate for a general system employing the adaptive hybrid ARQ with acknowledgements that arrive instantly on an error-free return channel. The throughput is obtained as a function of the signal-to-noise ratio for an example quad rate system employing convolutional codes with non-coherent frequency shift keying over the uncorrelated Rayleigh fading channel. This allows the best choice for the parameters of the algorithm to be made. In the case that the channel bit errors are independent, the generalization offers performance improvement of less than 10% over that in [1]. But when the channel errors are bursty, as in the case of Rayleigh fading with finite bit interleaving, the generalization offers throughput improvement as high as 24%. We go on to consider incorporating code combining with the adaptive scheme to form an adaptive memory hybrid ARQ. Simulation of a system using complementary punctured convolutional codes with 4 code rates shows that 2-level code combining can extend the adaptive scheme's useful throughput into the low SNR region by approximately 4 dB.     

Markov model aided decoding for image transmission usingsoft-decision-feedback

Soft-decision-feedback MAP decoders are developed for joint source/channel decoding (JSCD) which uses the residual redundancy in two-dimensional sources. The source redundancy is described by a second order Markov model which is made available to the receiver for row-by-row decoding, wherein the output for one row is used to aid the decoding of the next row. Performance can be improved by generalizing so as to increase the vertical depth of the decoder. This is called sheet decoding, and entails generalizing trellis decoding of one-dimensional data to trellis decoding of two-dimensional data (2-D). The proposed soft-decision-feedback sheet decoder is based on the Bahl algorithm, and it is compared to a hard-decision-feedback sheet decoder which is based on the Viterbi algorithm. The method is applied to 3-bit DPCM picture transmission over a binary symmetric channel, and it is found that the soft-decision-feedback decoder with vertical depth V performs approximately as well as the hard-decision-feedback decoder with vertical depth V+1. Because the computational requirement of the decoders depends exponentially on the vertical depth, the soft-decision-feedbark decoder offers significant reduction in complexity. For standard monochrome Lena, at a channel bit error rate of 0.05, the V=1 and V=2 soft-decision-feedback decoder JSCD gains in RSNR are 5.0 and 6.3 dB, respectively.     

Effect of hygrothermal ageing on the monotonic and cyclic loading of glass fiber reinforced polyamide

The properties of short glass fiber reinforced thermoplastic based on polyamide 6 in humid environment are studied. Conditioning was conducted at 90°C. The combined action of water and heat (90°C) affects progressively the mechanical properties. When the injection molded samples were subjected to moisture, decrease in tensile strength and elastic modulus was observed whatever in distilled water or in salt solution. However, there is an enhancement of elongation at break with increasing exposure to humidity. After immersion in water, the fatigue life time is drastically reduced. Scanning electron microscope (SEM) was used in order to examine the fractured samples feature. Results show that water diffuses into the polymer leading to a reduction of the interfacial stress transmissibility. The major contributor of the stiffness loss is the adhesion loss between the fibers and the polymer. POLYM. COMPOS., 35:501–508, 2014. © 2013 Society of Plastics Engineers