Crushing behaviour of composite hemispherical shells subjected to quasi-static axial compressive load

This paper examines the effects of composite constituents and geometry on the energy absorption capability of composite hemispherical shells. To examine the effects of matrix types on their energy absorption capability, glass fibre/epoxy and glass fibre/polyester hemispherical shells were fabricated. While glass fibre/epoxy and carbon fibre/epoxy hemispherical shells were fabricated to investigate the effect of fibre reinforcements. Effect of aspect ratio (R/t) was also examined and the results were presented. The results obtained showed that the energy absorption capability of the hemispherical shells significantly affected by the composite constituents as well as R/t ratio.     

Seasonal occurrence and toxicity of Microcystis spp. and Oscillatoria tenuis in the Lebna Dam, Tunisia

Physicochemical and biological water quality, including the total microcystin concentrations, was investigated for the first time from January to December 2005 in the Lebna Dam, Tunisia. Microcystin levels and characterization of the different microcystin variants present were measured by protein phosphatase (PP2A) inhibition assays and by LC/MS/MS, respectively. Nutrient values were high, with total inorganic nitrogen and phosphorus concentrations ranging from 0.05 to 8.4 mg L(-1) and from 0.03 to 1.37 mg L(-1), respectively. However, the chlorophyll-a concentrations were very low with a peak (5.32 microg L(-1)) on 20 September 2005 at 9 m depth water samples. Microscopic examination of the phytoplankton samples showed the dominance in the autumn of three morphospecies of the genus Microcystis and the species Oscillatoria tenuis. The total (particulate and dissolved) microcystin concentrations at the surface and at 9 m depth water samples ranged between 0.008 and 1.73, and 0.005 and 5.57 microg microcystin (MC)-LR equivalent L(-1), respectively, with a peak on 20 September. The presence of the microcystin synthetase genes (mcyA, -B, and -C) in the lysates of the three morphospecies of the genus Microcystis and the species O. tenuis indicated that these species were responsible for the microcystin production in this system. The analysis of the field cyanobacterial sample extract containing these species by LC/MS/MS revealed the presence of two microcystin variants: microcystin-LR (MC-LR) and microcystin-YR (MC-YR).     

Occurrence of Vibrio spp. in blue mussels (Mytilus edulis) from the German Wadden Sea

The present study aimed at determining the contamination of blue mussels grown in Germany with relevant bacterial organisms. Seasonal variations were examined. For that purpose, mussel samples were taken regularly between June 2004 and May 2005 in seven shellfish-growing areas of the German Wadden Sea. A total of 90 samples were analysed. The analysis included the compulsory microbiological parameters Escherichia coli and Salmonella spp., as well as the determination of the contamination with Vibrio spp. Although the analysed mussels complied with the legislation in force, potential human pathogens were detected in a wide range of samples. Vibrio spp. was detected in 74.4% of the samples analysed in this study. Among Vibrio isolates, Vibrio alginolyticus was the species most frequently detected (51.2%), followed by Vibrio parahaemolyticus (39.5%). Vibrio vulnificus was detected in 3.5% of the samples. V. parahaemolyticus and V. vulnificus were not found in samples collected at low water temperatures. The results indicate that blue mussels from shellfish-growing areas in the German Wadden Sea regularly contain pathogens relevant to public health. They also show that E. coli is not a reliable indicator for the contamination with Vibrio spp. To improve consumer protection, it therefore seems necessary to extend the analysis of mussels for direct human consumption by additional parameters.     

Phenolic Composition,Essential Oil,and Antioxidant Activity in the Aerial Part of Artemisia Herba-Alba from Several Provenances: A Comparative Study

This study characterized the phenolic, aroma compositions, and antioxidant capacities of four Artemisia herba alba accessions collected from north and center regions in Tunisia in order to select valuable origin with optimal bioactive compounds production. The total polyphenol and flavonoid contents varied between accessions with maxima contents observed in center regions. Kaempherol, apigenin, naringenin, p-coumaric, trans-cinnamic, and caffeic acids were the most abundant compounds with percentage varying depending on the considered accession. Significant changes on essential oil yields (0.4–1.2%) were found between accessions and three different oil chemotypes were distinguished: camphor, fenchol/α-thujone, and α-thujone/camphor. Cluster analysis of volatile and phenolic compositions grouped the accessions on different groups. Antioxidant activities of extracts were found to be higher than essential oils for the four provenances. The results suggested that the center regions have high potential for selecting varieties rich on essential oil, antioxidant phenolic acids, and flavonoids.     

Isolation of fermentative microbial isolates from sugar cane and beet molasses and evaluation for enhanced production of bioethanol

In an attempt to produce bioethanol as a renewable and natural energy resource and as a promising alternative/complement to conventional petrol (i.e., gasoline), 44 microbial isolates (12 yeast and 32 bacterial strains) were isolated from molasses samples obtained from some of the sugar factories in Egypt. Among the microbial isolates obtained, only two yeast isolates (HSC-22 and HSC-24) were selected from sugarcane molasses (SCM) for their high bioethanol fermentation capabilities, recording bioethanol production of ≈9.6 and 8.2 g/L with actual yield of 0.48 and 0.41 g ethanol/g SCM, respectively, within 48-h incubation period at 30°C. Phylogenetic identification of these isolates was performed based on the analysis of the nucleotide sequence of the 18S rDNA gene, which indicated that these isolates can be identified as Pichia veronae and Candida tropicalis, respectively, with similarity of 99%.     

Pea and Broad Bean Pods as a Natural Source of Dietary Fiber: The Impact on Texture and Sensory Properties of Cake

Attention has focused on bakery products such as cake which is one of the most common bakery products consumed by people in the world. Legume by‐products, pea pods (PPs) (Pisum sativum L.) and broad bean pods (BBPs) (Vicia faba L.) mediterranean (Tunisian), has been studied for its high dietary fiber content (PP: 43.87 g/100 g; BBP: 53.01 g/100 g). Protein content was also a considerable component for both by‐products. We investigated the effect of substituted of 5%, 10%, 15%, 20%, 25%, and 30% of PP and BBP flours on the sensory and technological properties in cake. Cakes hardness increased whereas L^* and a^* color values decreased. The overall acceptability rate showed that a maximum of 15% of PP and BBP flours can be added to prepare acceptable quality cakes.     

Assessment of solar and wind energy as motive for potential hydrogen production of Algeria country; development a methodology for uses hydrogen-based fuel cells

This study is based on method of storing the part of renewable energy in the hydrogen form for using in a fuel cell at the absence of solar radiation due to overcast day or in the night. In addition, the system advantage don't need a batteries compared with other systems. The present work is compared energy potential of the wind and solar with the results of hydrogen production and to address the various obstacles to study and evaluation. This work is assessment the renewable resources in various sites of Algeria, especially in Adrar area which is one regions of the high solar energy in the world, where the radiation rates exceed more than $2300kWh/m^2$ per year, the area is also characterized by high wind power. In fact, by these two energy sources (solar and wind) that it characterized by Adrar, it's interesting to combine electrical producing energy and hydrogen production. The studies indicate that there are the meteorological factors related to the nature of site (irradiation, temperature and wind speed) are linked to the generation of electricity by renewable energy. The results obtained showing that the hydrogen production related to the solar radiation values, where southern of Algeria has more hydrogen potential compared with the northern. The simulation results show that the energy supplied by a photovoltaic module type UDTS 50 can supply energy for ten electrolyzer cells which are connected in series with this module.     

Bewertung von Setzungsmessungen flachgegründeter Gebäude in weichen Böden

Evaluation of settlement measurements of buildings with shallow foundation on soft soils. Available settlement measurements of 10 buildings with shallow foundations on lacustrine clay in Southern Germany represent the basis of a statistical evaluation of the primary‐ as well as the creep‐settlement. Generally, the measurements show that the predicted settlements using the standard one‐dimensional consolidation tests are significantly larger than the actually occurred settlements. According to the evaluation a correction factor to the calculation of settlement in soft soils was derived. By means of back‐analysis of the measured settlements the coefficients of the consolidation and the secondary compression are determined so that the time‐settlement behavior could be also investigated.     

Synthesis and Characterization of Polyaniline,Poly(3-fluoroaniline), and Poly(aniline-co-3-fluoroaniline) Derivatives Obtained by Chemical Oxidative Polymerization Methods

The syntheses of thermally stable, conducting polyaniline, poly(3-fluoroaniline), and poly(aniline-co-3-fluoroaniline) derivatives by chemical oxidative polymerization methods are described. By varying the mol% of 3-fluoroaniline in the monomer feed, a series of new poly(aniline-co-3-fluoroaniline) derivatives with different chemical compositions were prepared by chemical oxidative copolymerization methods using ammonium persulfate as oxidant in the presence of hydrochloric acid as the dopant. The chemical oxidative copolymerization of aniline with 3-fluoroaniline affords poly(aniline-co-3-fluoroaniline) derivatives with increased solubility properties, greater thermal stability, improved morphological control, and enhanced electrical characteristics, which promotes the processibility of the different fluorine-functionalized polyaniline derivatives when compared with the parent polyaniline homopolymer.

Poly(3-fluoroaniline) and the different poly(aniline-co-3-fluoroaniline) derivatives show better solubility and thermal stability than the polyaniline homopolymer, due to the incorporation of the F atoms along the fluorine-functionalized polyaniline backbone. Furthermore, the poly(3-fluoroaniline) homopolymer is thermally more stable than the polyaniline homopolymer due to the presence of the C–F bonds of the 3-fluoroaniline units along the polymer backbone. The electrical conductivity of the different poly(3-fluoroaniline) derivatives is dependent on the 3-fluoroaniline content in the polymer derivative and the morphology of the specific copolymer. The poly(3-fluoroaniline) homopolymer exhibits the lowest electrical conductivity. In addition, the electrical conductivity of the different poly(aniline-co-3-fluoroaniline) derivatives decreases with increasing 3-fluoroaniline content in the copolymer. The different polymer derivatives were characterized by proton nuclear magnetic resonance (¹H NMR) spectrometry, fourier transform infrared (FTIR) spectroscopy, ultraviolet visible (UV–Vis) spectroscopy, thermogravimetric analyses, scanning electron microscopy, and electrical conductivity measurements.     

The structural,dielectric and magnetic study of cobalt based spinel ferrites and polypyrrole composites

The CoFe₂O₄ was prepared via co-precipitation route, and in situ polymerization was used to prepare the polypyrrole, for the fabrication of nanocomposite. Two-point probe techniques, X-ray diffraction (XRD), as well as vibrating sample magnetometer (VSM) were used to investigate the electrical, magnetic, and structural characteristics of all the synthesized samples. In nanocomposites with higher ferrite concentrations, XRD peaks became more intense, and their widths becomes narrowed. The ferrite content enhanced the dc resistivity as well activation energy of the materials. The hysteresis loop identified the ferromagnetic property. The super paramagnetic behavior has been observed in samples PF1 (with 25% ferrites) and PF2 (having 50% ferrite ratio). These two samples might be employed in hyperthermia, which is a cancer therapy approach.