Major antioxidant constituents from Satureja hortensis L. extracts obtained with different solvents

Analysis of different extracts of Satureja hortensis L. obtained with various solvents (by supercritical CO₂ and by traditional extraction techniques) is presented in this study to identify and to determine the major constituents responsible for the antioxidant activity. The total polyphenol and total flavonoid contents of the extracts were determined by spectrophotometric method and no correlation was found with the antioxidant activites. HPLC was also used to measure two diterpenes as carnosol and carnosic acid in the extracts. Neither carnosol nor carnosic acid were identified. Individual antioxidants as rosmarinic and caffeic acids were identified and quantified with TLC‐densitometry method. Rosmarinic acid was found in higher amount than caffeic acid. The content of rosmarinic acid was also determined with HPLC. A good correlation coefficient of 0.85 was found between the antioxidant activity and amount of rosmarinic acid, which leads to the conclusion that rosmarinic acid is among the main antioxidant compounds of S. hortensis L. plant.     

Enhanced ferroelectric properties of La-substituted BiFeO3 thin films on LaSrCoO3/Pt/TiO2/SiO2/Si (1 0 0) substrates prepared by the soft chemical method

Bi_0.85La_0.15FeO₃ (BLFO015) thin films were deposited by the polymeric precursor solution on La_0.5Sr_0.5CoO₃ substrates. For comparison, the films were also deposited on Pt bottom electrode. X-ray diffraction data confirmed the substitutions of La into the Bi site with the elimination of all secondary phases under a substitution ratio x = 15% at a temperature of 500 °C for 2 h. A substantial increase in the remnant polarization (P_r) with La_0.5Sr_0.5CoO₃ bottom electrode (P_r ≈ 34 μC/cm²) after a drive voltage of 9 V was observed when compared with the same film deposited on Pt substrate. The leakage current behavior at room temperature decreased from 10^?8 (Pt) to 10^?10 A/cm² on (La_0.5Sr_0.5CoO₃) electrode under a voltage of 5 V. The fatigue resistance of the Au/BLFO015/LSCO/Pt/TiO₂/SiO₂/Si (1 0 0) capacitors with a thickness of 280 nm exhibited no degradation after 1 × 10⁸ switching cycles at a frequency of 1 MHz.     

Supercritical Fluid Extraction of Eucalyptus globulus Bark-A Promising Approach for Triterpenoid Production

Eucalyptus bark contains significant amounts of triterpenoids with demonstrated bioactivity, namely triterpenic acids and their acetyl derivatives (ursolic, betulinic, oleanolic, betulonic, 3-acetylursolic, and 3-acetyloleanolic acids). In this work, the supercritical fluid extraction (SFE) of Eucalyptus globulus deciduous bark was carried out with pure and modified carbon dioxide to recover this fraction, and the results were compared with those obtained by Soxhlet extraction with dichloromethane. The effects of pressure (100-200 bar), co-solvent (ethanol) content (0, 5 and 8% wt), and multistep operation were studied in order to evaluate the applicability of SFE for their selective and efficient production. The individual extraction curves of the main families of compounds were measured, and the extracts analyzed by GC-MS. Results pointed out the influence of pressure and the important role played by the co-solvent. Ethanol can be used with advantage, since its effect is more important than increasing pressure by several tens of bar. At 160 bar and 40 °C, the introduction of 8% (wt) of ethanol greatly improves the yield of triterpenoids more than threefold.     

How much nitrogen is fixed by biological symbiosis in tropical dry forests? 1. Trees and shrubs

Despite the recognized importance of the process, estimates of the amount of nitrogen fixed by biological symbiosis in tropical dry forests are almost nonexistent. We estimated the nitrogen fixed annually by the leaves of trees and shrubs at sites regenerating for 16 and 38?years and in an old-growth dry forest using ¹⁵N abundance methodology. The total leaf biomass (1,824?C3,036?kg?ha^?1) and nitrogen contents (62?C90?kg?ha^?1) did not differ among the areas. In all of the areas, most of the leaf biomass belonged to legume plants, but the proportion of the N₂-fixing legumes decreased with increasing regeneration time. In the 16-year regenerating area, almost all of the N was in the leaves of the N-fixing Mimosa tenuiflora plants, but fixation was absent or very low as it was in the N-fixing species present in the 38-year regenerating area. In the old-growth Caatinga, all of the N-fixing species (M. tenuiflora, Piptadenia stipulacea and Anadenanthera colubrina) had large proportions (47?C62?%) of their N derived from atmospheric N₂, but the amount of fixed N (6?kg?ha^?1) was a small proportion of the total leaf N because these plant species were a small part of the vegetation. The total input of biologically fixed N to the old-growth forest was similar in magnitude to an estimate made for a humid tropical forest in Amazonia.     

How much nitrogen is fixed by biological symbiosis in tropical dry forests? 2. Herbs

Although biological nitrogen fixation (BNF) is considered the main input of N in mature and regenerating native tropical vegetation, it has seldom been quantified. Biomass and N accumulation and fixation were determined for spontaneously occurring herbaceous species in caatinga areas in four regeneration stages (2, 17, 39 and >50?years after abandonment from agricultural use). BNF was estimated using the ¹⁵N natural-abundance method. The 2-year regeneration area had the highest total herb (6,355?kg?ha^?1) and legume (262?kg?ha^?1) biomass production, N stocks (82?kg?ha^?1) and fixed N (5.0?kg?ha^?1). N₂-fixing legumes (nine species in the sampled area) contributed over 97?% of legume biomass in all areas. Macroptilium gracile added the largest amount of N (3.9?kg?ha^?1 in the 2-year regeneration area) because of its large biomass production (205?kg?ha^?1), although it was not the species with the highest proportion of fixed N (76?%). All of the N₂-fixing species obtained large proportions of their N from symbiosis, most of them more than 50?%.However, the amounts of fixed N per unit area were relatively low (0.22?C5.00?kg?ha^?1) because the biomass of N₂-fixing species was always less than 5?% of the total herb biomass.     

Microstructure of Reaction Zone Formed During Diffusion Bonding of TiAl with Ni/Al Multilayer

In this article, the characterization of the interfacial structure of diffusion bonding a TiAl alloy is presented. The joining surfaces were modified by Ni/Al reactive multilayer deposition as an alternative approach to conventional diffusion bonding. TiAl substrates were coated with alternated Ni and Al nanolayers. The nanolayers were deposited by dc magnetron sputtering with 14 nm of period (bilayer thickness). Joining experiments were performed at 900 °C for 30 and 60 min with a pressure of 5 MPa. Cross sections of the joints were prepared for characterization of their interfaces by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), high resolution TEM (HRTEM), energy dispersive x-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Several intermetallic compounds form at the interface, assuring the bonding of the TiAl. The interface can be divided into three distinct zones: zone 1 exhibits elongated nanograins, very small equiaxed grains are observed in zone 2, while zone 3 has larger equiaxed grains. EBSD analysis reveals that zone 1 corresponds to the intermetallic Al₂NiTi and AlNiTi, and zones 2 and 3 to NiAl.     

Effect of the injection parameters on diesel spray characteristics

The characteristics of the diesel spray have affected certain aspects of engine performance, such as the power, fuel consumption, and emissions. Therefore, this study was performed to investigate the effects of various injection parameters. In order to obtain the effect of injection parameters on diesel spray characteristics, the experiment is performed by using a high temperature and pressure chamber. The behaviors of the spray are visualized by using a high speed video camera, spray angle, penetration, and various other things.     

A corrosion study of nanocrystalline copper thin films

Thin nanocrystalline, compact films, based on the copper–nitrogen system, up to 2.5 μm thickness and 3.5% nitrogen, were deposited by magnetron sputtering at different partial pressure ratios of N₂ and Ar, without formation of Cu_xN compounds, the nitrogen concentration influencing grain size (down to 30 nm) and film homogeneity. Electrochemical corrosion properties were investigated using polarization curves and electrochemical impedance spectroscopy in 0.5 M NaCl aqueous solution, and compared with pure bulk copper; morphology was examined by scanning electron microscopy. Significant variations in corrosion currents between samples were attributed to grain size and structural defects on the grain boundaries.     

Targeted reconstruction with differential planar computed tomography

In computed tomography, targeted (or zoomed) reconstruction is usually used to achieve high-resolution reconstruction to a small region-of-interest (ROI). This paper reports a novel targeted reconstruction method based on the recently developed differential planar computed tomography technology. With the central-slice sinogram of scanning a planar object, the primary orientation of the object is first determined for the first projection. Then by identifying the dimensions of the ROI and its offsets to the centre-of-rotation (COR), the targeted reconstruction matrix is defined, which just covers the ROI and follows its initial orientation at the scan start time. By scanning and reconstructing a small planar ROI soldered on a large planar substrate, we demonstrate the advantages of the proposed method over traditional CT, including the smaller reconstruction size and less computation time, high-resolution reconstruction and good-orientated CT image for subsequent de-layering and visualization.     

Ni/Al Multilayers Produced by Accumulative Roll Bonding and Sputtering

Journal of Materials Engineering and Performance - Ni/Al multilayers are known to transform into NiAl in a highly exothermic and self-sustaining reaction. The fact that this reaction has a high...