Essential Oil and Phenolic Compounds of Artemisia herba-alba (Asso.): Composition,Antioxidant, Antiacetylcholinesterase,and Antibacterial Activities

Total phenols, flavonoids, flavonols, and flavanols of the methanolic extract of the aerial part of Artemisia herba-alba were determined. The extract was analyzed by liquid chromatography with photodiode array coupled with electrospray ionisation mass spectrometry and allowed to identify of 10 phenolic compounds. Apigenin-6-C-glycosyl flavonoids and caffeoylquinic acids were identified. Chlorogenic acid and 1,4 dicaffeoylquinic acid being the major constituents. The essential oil obtained by hydrodistillation was analyzed by gas chromatography–mass spectrometry. Twenty-three compounds, representing 97.8% of the total oil, were identified. The most abundant components were β-thujone (41.9%), α-thujone (18.4%), and camphor (13.2%). Methanolic extract and essential oil exhibited a considerable antioxidant activity as evaluated by 2,2-diphenyl-pycrilhydrazil hydrate scavenging activity, reducing power, β-carotene bleaching test, and chelating ability. The methanolic extract was found to be more efficient, while the essential oil exhibited the highest acetylcholinesterase inhibitory activity. Analysis of the antibacterial activity showed that A. herba-alba methanolic extract and essential oil are efficient against gram positive and gram negative bacteria.     

Electrochemical properties of doped lithium titanate compounds and their performance in lithium rechargeable batteries

Several substituted titanates of formula Li_4−xMg_xTi_5−xV_xO₁₂ (0 ≤ x ≤ 1) were synthesized (and investigated) as anode materials in rechargeable lithium batteries. Five samples labeled as S1–S5 were calcined (fired) at 900 °C for 10 h in air, and slowly cooled to room temperature in a tube furnace. The structural properties of the synthesized products have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transmission infrared (FTIR). XRD explained that the crystal structures of all samples were monoclinic while S1 and S3 were hexagonal. The morphology of the crystal of S1 was spherical while the other samples were prismatic in shape. SEM investigations explained that S4 had larger grain size diameter of 15–16 μm in comparison with the other samples. S4 sample had the highest conductivity 2.452 × 10⁻⁴ S cm⁻¹. At a voltage plateau located at about 1.55 V (vs. Li ⁺), S4 cell exhibited an initial specific discharge capacity of 198 mAh g⁻¹. The results of cyclic voltammetry for Li_4−xMg_xTi_5−xV_xO₁₂ showed that the electrochemical reaction was based on Ti⁴⁺/Ti³⁺ redox couple at potential range from 1.5 to 1.7 V. There is a pair of reversible redox peaks corresponding to the process of Li⁺ intercalation and de-intercalation in the Li–Ti–O oxides.     

Utilisation of solar photovoltaic pumping for aeration systems in aquaculture ponds

This research pertains to solar photovoltaic (PV) pumping for aeration of aquaculture ponds and evaluates it economically. A stand-alone photovoltaic aeration system based on recycling of water at 10 cm under the water surface, at the surface (0 cm) and above the surface (30 cm) on a perforated tray was evaluated. The effect of pump discharges (35, 50, 65 L/min) on standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE) was investigated. Results revealed that the daily averages of PV energy output, PV efficiency and load energy were 0.844 kWh/d, 9.87% and 0.615 kWh/d, respectively, at 65 L/min and 42.7°C PV temperature. Water flow upward at 30 cm over the perforated tray in the radial direction proved to be better since it gave an opportunity for the exchange of gaseous between the water and the atmosphere. The SOTR and SAE for the third position were 0.025 kgO₂/h and 0.1 kgO₂/kW h, respectively.     

Load bearing properties of three‐component polymer composites

Metal or solid polymer anchors are used as the load transfer components for foam and foam composites when they are used as the structural elements in design. The traditional method of fixation of these components is by fastening and adhesion. In this study, anchors were created in the form of inserts and were imbedded in the sandwich composite during the foaming process, resulting in the manufacture of three‐component composite. Flexure tests were conducted to study the effect of different geometries (rectangular, cylindrical, tapered/wedge shaped) and lengths of metal inserts on the strengths of sandwich composites. The stress strain response, mode of fracture of sandwich composite with metallic anchors was elucidated. The results showed that long tapered inserts imbedded in sandwich composite provide better load bearing and adhesion properties than other geometries. A model is presented that describes the relationship between stiffness reduction and progressive crack length of sandwich composite. Finite element analysis (FEA) of the interactions between the inserts and sandwich composites under different loads were carried out. FEA modeling and experimental results were in good agreement, thus validating the model. POLYM. COMPOS., 31:1731–1737, 2010. © 2010 Society of Plastics Engineers.     

Corrosion Inhibition by Some Cationic Surfactants in Oil Fields

Two cationic surfactants, namely, tetradecyl dimethyl benzyl ammonium chloride (TDBAC) and tributyl tetradecyl phosphonium chloride (TTPC) were supplied from the local market and characterized. The adsorption tendency of the two surfactants was estimated from the values of the depression of surface tension of the water at the critical micelle concentration. The studied surfactants were evaluated as antimicrobial agents against sulfate-reducing bacteria. These cationic surfactants showed good antimicrobial activities against the tested microorganisms. It was also found that these compounds are good corrosion inhibitors for carbon steel in 0.5?M HCl at doses of 25?C600?ppm.     

Mycotoxin production in wheat grains by different Aspergilli in relation to different relative humidities and storage periods

Four different Aspergilli (Aspergillus oryzae, A. parasiticus, A. terreus and A. versicolor) were grown on wheat grains underdifferent degrees of relative humidity 14, 50, 74, 80 and 90%. Samples of wheat grains were taken monthly for a period of six months and examined for mycotoxin production. A. oryzae was found to produce aflatoxins B1, B2, zearalenone, DON and T-2 toxins under elevated degrees of humidity and prolonged periods of storage. A. parasiticus produced aflatoxins B1, G1, NIV, DON and T-2 toxins in high concentrations during a period of not more than three months storage at 14% relative humidity; at an increased level of relative humidity of 74% ochratoxin A, zearalenone and sterigmatocystin were also produced at high levels. The isolate was drastic in toxin production. A. terrus produced toxins at 14% relative humidity (aflatoxin G2 and DON) at levels much higher than any other prevalent degrees of humidity. A. versicolor is highly sensitive to relative humidity and grain moisture content It produced aflatoxins B1, G1, NIV and DON at a relative humidity of 50% and another toxins (aflatoxin G2, ochratoxins A, B and zearalenone) at 74%. The microorganism can be considered a trichothecene producer under suitable relative humidity.     

Low Power Semi-systolic Architectures for Polynomial-Basis Multiplication over GF(2m) Using Progressive Multiplier Reduction

We present low area and low power semi-systolic array architectures for polynomial basis multiplication over GF(2^m) using Progressive Multiplier Reduction Technique (PMR). These architectures are explored using linear and nonlinear techniques applied to the polynomial multiplication algorithm. The nonlinear techniques allow the designer, to control the processor workload and reduce the inter-processor communications. The semi-systolic architectures obtained have simple structure with local communication. ASIC implementations of our designs and comparable published designs show that the proposed scalable semi-systolic structures have less area complexity (56.8–94.6 %) and power consumption (55.2–84.2 %) except for a scalable design published by the same authors. However, one of the proposed scalable designs outperforms this design in terms of throughput by 73.8 %. This makes the proposed designs suited to embedded applications that require low power consumption and moderate speed.