Levels of essential and non-essential metals in leaves of the tea plant (Camellia sinensis L.) and soil of Wushwush farms,Ethiopia

Five tea clones of the Camellia assamica variety grown in Wushwush tea plantation farms, Ethiopia, were analyzed for their contents of essential, non-essential and toxic metals (K, Ca, Mg, Fe, Mn, Cu, Zn, Na, Cd and Pb) by atomic absorption flame emission spectroscopy. Both the tea leaves and the soils of the study farms showed similar accumulation patterns in their contents of the studied macronutrients. Among the macronutrient metals, K was the most abundant element in the tea leaves (17.7–24.8 mg/g) and the soils (7.14–9.73 mg/g). Mn was the predominant micronutrient heavy metal in the tea leaf tissues ranging between 501 and 1281 mg/kg. Level of Fe (29.6–100 mg/kg) in the leaf tissue was found to be the second most abundant micronutrient next to Mn whereas concentrations of Cu and Co were relatively lower both in the soil and tea samples. The toxic heavy metals Pb and Cd in the leaf tissues were present at levels too low to be detected by the analytical technique used in this study. The soils were found to be acidic (pH 5.04–5.49) with high organic matter (5.48–6.02%). Fe was the most abundant metal followed by Mn, Na and Zn in the soils. Unlike the tea leaves, the soils were found to contain traces of the toxic metal, Cd (0.02–1.10 mg/kg). The levels of most of the metals determined in this study compared well with those reported for tea leaves from some other parts of the world.     

Probabilistic prediction of minimum fatigue life behaviour in α + β titanium alloys

The objective of this work was to develop and demonstrate a probabilistic life prediction method for the prediction of minimum fatigue lives that are typically used in the design of fracture critical rotating turbine engine components. A Monte Carlo analysis was used to predict the variability in fatigue lives based on the distribution of microstructural features that lead to early crack initiation as well as the variability in small fatigue crack growth rates. Two titanium alloys, both with bimodal microstructures, were tested and analysed in this study. The distribution of critical microstructural features was calibrated based on test results and understanding of microstructure neighbourhood effects. Testing was conducted on both alloys and included both smooth and notched specimens. The predictions are presented and compared with the data for smooth and notch geometries for the various loading conditions. A parametric study was performed to identify the importance of several model inputs and to identify areas for future improvement.     

Alcohol Determination in Distilled Alcoholic Beverages by Liquid Phase Fourier Transform Mid-Infrared and Near-Infrared Spectrophotometries

Fourier transform mid-infrared spectrophotometry (FT-MIR), 1180–950 cm^?1, and near-infrared spectrophotometry (NIR), 1720–1660 nm, have been used complementarily for the direct determination of ethanol and methanol in distilled alcoholic beverages. In mid-infrared ethanol and methanol identified separately, hence, it has been used to confirm the absence or presence of methanol. In the absence of methanol, both were used to determine the alcoholic strength independently; however, near-infrared was used without diluting the samples. Ethanol and methanol contents were evaluated using the calibration curves established by a plot of peak height or peak area versus concentration % (w/w). The linearity range for ethanol was up to 15 and 50 % (w/w) for mid- and near-infrared, respectively. The developed methods are simple, fast, precise, and accurate. Moreover, the results obtained were in excellent agreement with the results obtained from gas chromatographic measurements. No sample preparation was required at all, and in all samples, methanol was not detected.     

A compact configuration of semicircular metasurface loaded slot antenna for beam steering application

In this article, a compact beam steering antenna configuration is presented. The proposed structure comprises a semicircular radially gradient metasurface (SCRGM) and a slot antenna. This metasurface (MS) with the dimensions of 3.17λ₀² covers only half of the antenna aperture by placing it at a height of 0.16λ₀ from the slot antenna. The SCRGM is made up of four different semicircular regions, which introduce progressive phase delay to the impinging spherical electromagnetic waves from the slot antenna. The placement of the SCRGM tilts the main beam by 30° away from the normal direction. Furthermore, in‐plane movement (rotation and translation) of the SCRGM facilitates beam steering in the elevation plane (E‐plane) with the total scanning range of 60°. Moreover, in simulation, two SCRGMs are placed at both sides of antenna aperture to independently control the beam directions in both upper and lower hemispheres of the slot antenna. Due to the symmetry of the slot antenna, only one SCRGM is tested during the measurement process and the same outcome is expected for the other MS. Considerably small volume (0.50λ₀³) of the structure revealed compact antenna configuration. Moreover, independent control of the beam directions in both of the hemispheres makes proposed antenna a suitable candidate for various applications.     

Effect of Minor Additions of Boron on Microstructure and Mechanical Properties of As-Cast Near α Titanium Alloy

This work investigates the effect of boron addition on the microstructure and mechanical properties of a near alpha Ti alloy, Timetal 685 in as-cast plus heat-treated condition. While significant refinement of the prior β grain size is seen with small additions of boron, the thickness of α lath (in transformed β structure) increases with increasing boron. At room temperature (RT), tensile yield strength increases marginally, but the ductility drops significantly possibly because of the cracking of TiB phase. At elevated temperature, significant strengthening is observed in the boron containing alloys especially at higher plastic strains. Additionally, the creep resistance shows significant enhancement with boron addition.     

Simultaneous Determination of Alkaloids in Green Coffee Beans from Ethiopia: Chemometric Evaluation of Geographical Origin

The alkaloid compositions of 99 green coffee (Coffea arabica L.) bean samples comprising eight varieties (Harar, Jimma, Kaffa, Wollega, Sidama, Yirgachefe, Benishangul and Finoteselam) from the major production regions of Ethiopia were investigated. High performance liquid chromatography was applied for the simultaneous determination of four coffee alkaloids in the aqueous extracts of the beans. The limits of detection for the method were established as 13 mg kg^?1 for trigonelline, 7 mg kg^?1 for theobromine, 8.5 mg kg^?1 for caffeine and 4 mg kg^?1 for theophylline in the dry coffee beans. Theophylline was not detected in any of the samples. The determined concentrations (% w/w dry coffee beans) ranged from 0.98 to 1.32 % for trigonelline, 0.0048 to 0.0094 % for theobromine and 0.87 to 1.38 % for caffeine. The concentrations of the alkaloids varied significantly, depending on the geographical origin of the beans. Theobromine was not detected in coffee beans from the East (Harar coffees), and its absence in samples can be used to ascertain whether the coffee originates from this region. Coffee beans from the Northwest were characterized by higher concentrations of caffeine. Application of linear discriminant analysis provided 75 % correct classification of samples into the respective production regions, with a 74 % prediction success rate. The moderate classification efficiency obtained when using alkaloid data demonstrates the potential of using this class of compounds in discriminant models for determination of the geographical origin of green coffee beans from Ethiopia.     

Natural dye–surfactant interactions: thermodynamic and surface parameters

The interaction of two Indian natural dyes, namely madder (Rubia cordifolia) and mallow (Punica granatum), with cationic surfactant cetyl trimethyl ammonium bromide and anionic surfactant sodium lauryl sulphate, has been studied. Spectrophotometric data showed a strong interaction between the natural dyes and the surfactants. The critical micelle concentration of the surfactants, determined by measurement of specific conductance and surface tension, was found to decrease on the addition of natural dyes in an aqueous solution of surfactants. The thermodynamic and surface parameters for the interaction have been evaluated.     

Predictive machine learning-based integrated approach for DDoS detection and prevention

Multimedia Tools and Applications - Distributed Denial of Service attack has been a huge threat to the Internet and may carry extreme losses to systems, companies, and national security. The...     

Effects of Thermomechanical Processing and Heat Treatment on the Tensile and Creep Properties of Boron-Modified Near Alpha Titanium Alloy Ti-1100

Tensile properties of boron-modified near alpha titanium alloy were evaluated in ??-??- and ??-processed conditions after heat treatments at different solution treatment temperatures at both room temperature and 873 K (600 °C). Creep behavior was also investigated in these processing and heat-treatment conditions at 873 K (600 °C). While the yield strength (YS) and the ultimate tensile strength (UTS) did not show significant dependence on the processing history, a marginal improvement in elongation-to-failure values were observed in ??-??-processed condition as compared with ??-processed condition at both temperatures. Creep resistance of the alloy at 873 K (600 °C) was found to be significantly superior in ??-processed condition as compared with ??-??-processed condition.