Determination of phenolic compounds by MALDI–TOF and essential oil composition by GC–MS during three development stages of Origanum majorana L.

This study aimed to investigate the effect of the maturation process of sweet marjoram (Origanum majorana L.) on essential oil composition, the phenolic profile of ethanolic extract and their antioxidant capacities. The essential oil composition was studied at three stages of maturity by GC–MS. Thirty compounds were detected representing 100% of the total essential oil. p‐Menth‐1‐en‐4‐ol was the major compound (37.15–76.94%) followed by cyclohexanol‐3,3,5 trimethyl (5.41–15.99%) and α‐terpineol (0.94–11.34%). During the maturation process, an accumulation of oxygenated monoterpenes was observed. The phenolic composition was studied using matrix‐assisted laser desorption/ionization time of flight. The analysis showed the presence of short flavonoid monomers at all stages of maturation. The antioxidant capacity of ethanolic extracts and essential oils was evaluated using the DPPH assay, iron chelating power and reducing power assay. The highest phenolic content and antioxidant capacity were found at flowering stage. These findings on essential oil composition, phenolic profile and antioxidant capacity of O. majorana at three different stages of development provide more information on how these secondary metabolites are accumulated.     

A nonlocal multi-point singular fractional integro-differential problem of Lane–Emden type

In this paper, using Riemann–Liouville integral and Caputo derivative, we study a nonlinear singular integro-differential equation of Lane–Emden type with nonlocal multi-point integral conditions. We prove the existence and uniqueness of solutions by application of Banach contraction principle. Also, we prove an existence result using Schaefer fixed point theorem. Then, we present some examples to show the applicability of the main results.     

A view about the short histories of the mole and Avogadro’s number

The mole and Avogadro’s number are two important concepts of science that provide a link between the properties of individual atoms or molecules and the properties of bulk matter. It is clear that an early theorist of the idea of these two concepts was Avogadro. However, the research literature shows that there is a controversy about the subjects of when and by whom the mole concept was first introduced into science and when and by whom Avogadro’s number was first calculated. Based on this point, the following five matters are taken into consideration in this paper. First, in order to base the subject matter on a strong ground, the historical development of understanding the particulate nature of matter is presented. Second, in 1811, Amedeo Avogadro built the theoretical foundations of the mole concept and the number 6.022 × 10²³ mol^?1. Third, in 1865, Johann Josef Loschmidt first estimated the number of molecules in a cubic centimetre of a gas under normal conditions as 1.83 × 10¹⁸. Fourth, in 1881, August Horstmann first introduced the concept of gram-molecular weight in the sense of today’s mole concept into chemistry and, in 1900, Wilhelm Ostwald first used the term mole instead of the term ‘gram-molecular weight’. Lastly, in 1889, Károly Than first determined the gram-molecular volume of gases under normal conditions as 22,330 cm³. Accordingly, the first value for Avogadro’s number in science history should be 4.09 × 10²² molecules/gram-molecular weight, which is calculated by multiplying Loschmidt’s 1.83 × 10¹⁸ molecules/cm³ by Than’s 22,330 cm³/gram-molecular weight. Hence, Avogadro is the originator of the ideas of the mole and the number 6.022 × 10²³ mol^?1, Horstmann first introduced the mole concept into science/chemistry, and Loschmidt and Than are the scientists who first calculated Avogadro’s number. However, in the science research literature, it is widely expressed that the mole concept was first introduced into chemistry by Ostwald in 1900 and that Avogadro’s number was first calculated by Jean Baptiste Perrin in 1908. As a result, in this study, it is particularly emphasised that Horstmann first introduced the mole concept into science/chemistry and the first value of Avogadro’s number in the history of science was 4.09 × 10²² molecules/gram-molecular weight and Loschmidt and Than together first calculated this number.     

Inclusive production of the meson in hadronic decays of the Z boson

The inclusive production rate of the ρ^±(770) vector meson in hadronic Z decays is measured with the ALEPH detector at the LEP collider. A total of 3.2 million hadronic events are selected from data recorded between 1991 and 1995. Decays of ρ^±→π⁰+π^± are reconstructed for x_E>0.05 and x_p>0.05 where x_p=p_ρ/p_beam and x_E=E_ρ/E_beam. The average ρ^± multiplicity per hadronic event is evaluated to be N(ρ^±)=2.59±0.03±0.15±0.04 where the first error is statistical and the second systematic. The third error is from the uncertainty in the extrapolation to x_p=x_E=0. The rates and differential cross-section are compared with Monte Carlo model predictions and OPAL measurements. Residual Bose–Einstein correlations are found to be an important component in the analysis.     

Effects of heavy metals and oxalate on the zeta potential of magnetite

Zeta potential is a function of surface coverage by charged species at a given pH, and it is theoretically determined by the activity of the species in solution. The zeta potentials of particles occurring in soils, such as clay and iron oxide minerals, directly affect the efficiency of the electrokinetic soil remediation. In this study, zeta potential of natural magnetite was studied by conducting electrophoretic mobility measurements in single and binary solution systems. It was shown that adsorption of charged species of Co(2+), Ni(2+), Cu(2+), Zn(2+), Pb(2+), and Cd(2+) and precipitation of their hydroxides at the mineral surface are dominant processes in the charging of the surface in high alkaline suspensions. Taking Pb(2+) as an example, three different mechanisms were proposed for its effect on the surface charge: if pH<5, competitive adsorption with H(3)O(+); if 56, precipitation of heavy metal hydroxides prevails. Oxalate anion changed the associated surface charge by neutralizing surface positive charges by complexing with iron at the surface, and ultimately reversed the surface to a negative zeta potential. Therefore the adsorption ability of heavy metal ions ultimately changed in the presence of oxalate ion. The changes in the zeta potentials of the magnetite suspensions with solution pH before and after adsorption were utilized to estimate the adsorption ability of heavy metal ions. The mechanisms for heavy metals and oxalate adsorption on magnetite were discussed in the view of the experimental results and published data.     

Continuous pH monitoring during pretreatment of yellow poplar wood sawdust by pressure cooking in water

Yellow poplar wood sawdust consists of 41% cellulose and 19% hemicellulose. The goal of pressure cooking this material in water is to hydrate the more chemically resistive regions of cellulose in order to enhance enzymatic conversion to glucose. Pretreatment can generate organic acids through acid-catalyzed degradation of monosaccharides formed because of acids released from the biomass material or the inherent acidity of the water at temperatures above 160°C. The resulting acids will further promote the acid-catalyzed degradation of monomers that cause both a reduction in the yield and the formation of fermentation inhibitors such as hydroxymethyl furfural and furfural. A continuous pH-monitoring system was developed to help characterize the trends in pH during pretreatment and to assist in the development of a base (2.0 M KOH) addition profile to help keep the pH within a specified range in order to reduce any catalytic degradation and the formation of any monosac-charide degradation products during pretreatment. The results of this work are discussed.     

Determination of selenium in atmospheric particulate material of Ankara and its possible sources

The monthly variation of selenium concentration in atmospheric particulate material of Ankara was investigated. The selenium concentrations in possible pollution source materials like coal, fuel oil and their bottom and fly ashes were determined to obtain the percent transference of selenium into the atmosphere. Instrumental thermal neutron activation analysis and atomic absorption spectroscopy were applied for the analysis of selenium in the samples. Selenium enrichment factors with respect to the fuels, soil of Ankara and crustal material were also calculated. Atmospheric selenium concentration is found to increase during winter months and the main cause of this increase is the emission of selenium into the atmosphere due to fuel combustion.     

Nonequilibrium synthesis and assembly of hybrid inorganic-protein nanostructures using an engineered DNA binding protein

We show that a protein with no intrinsic inorganic synthesis activity can be endowed with the ability to control the formation of inorganic nanostructures under thermodynamically unfavorable (nonequilibrium) conditions, reproducing a key feature of biological hard-tissue growth and assembly. The nonequilibrium synthesis of Cu(2)O nanoparticles is accomplished using an engineered derivative of the DNA-binding protein TraI in a room-temperature precursor electrolyte. The functional TraI derivative (TraIi1753::CN225) is engineered to possess a cysteine-constrained 12-residue Cu(2)O binding sequence, designated CN225, that is inserted into a permissive site in TraI. When TraIi1753::CN225 is included in the precursor electrolyte, stable Cu(2)O nanoparticles form, even though the concentrations of [Cu(+)] and [OH(-)] are at 5% of the solubility product (K(sp,Cu2O)). Negative control experiments verify that Cu(2)O formation is controlled by inclusion of the CN225 binding sequence. Transmission electron microscopy and electron diffraction reveal a core-shell structure for the nonequilibrium nanoparticles: a 2 nm Cu(2)O core is surrounded by an adsorbed protein shell. Quantitative protein adsorption studies show that the unexpected stability of Cu(2)O is imparted by the nanomolar surface binding affinity of TraIi1753::CN225 for Cu(2)O (K(d) = 1.2 x 10(-)(8) M), which provides favorable interfacial energetics (-45 kJ/mol) for the core-shell configuration. The protein shell retains the DNA-binding traits of TraI, as evidenced by the spontaneous organization of nanoparticles onto circular double-stranded DNA.     

Influence of salt stress on essential oil yield and composition of lemon grass (Cymbopogon schoenanthus L. Spreng. ssp. Laniger (Hook) Maire et Weil)

Cymbopogon is an aromatic plant valued for its citrus scent aroma. In this article, the effect of saline irrigation water on yield and quality of Cymbopogon schoenanthus L. was evaluated. Compounds of essential oils were identified by gas chromatography-mass spectrometry and/or (13)C-NMR spectroscopy. Results showed that the growth of the aerial part was not affected at a concentration of 50 mmol NaCl. Under salt stress, the content of major chemical compounds was affected differently by the treatment level.