Can glandular hair density be a breeding marker for Origanum vulgare subsp. hirtum with high essential oil content?

Origanum vulgare subsp. hirtum (Link) Ietswaart is an essential oil rich plant traditionally used as oregano. Based on the interest of the essential oil producing sector, in 2000 we have started a breeding program of O. vulgare subsp. hirtum. Plant material for our breeding work consists of 6 progeny. Individual evaluation of the plant material was carried out in 2008-2009 with the primary aim of finding mother plants with appropriate morphological features, high essential oil content (> 7%) and with carvacrol as the main essential oil component. Among the survey of morphological characteristics special attention was given to glandular hair density in order to test the usability of it as a morphological marker for screening progeny for high essential oil content. The characteristics of the progeny can be described with high variability ensuring the possibility of a good selection base. Evaluating the morphology, essential oil content and constitution of the individuals, 20 plants were selected on the grounds of their high (7-8.6%) essential oil content, high ratio (70-93%) of carvacrol in the essential oil and typical morphological features of O. vulgare subsp. hirtum. From the results of glandular hair density it can be stated that the correlation between glandular hair density of the upper, middle and lower leaves either on vegetative or generative shoots and essential oil content was never strong enough (correlation coefficient < or = 0.5) to use it exclusively as a morphological marker for individual selection.     

Secondary alpha isotope effects on deuterium tunneling in triplet o-methylanthrones: extraordinary sensitivity to barrier width

The rates of deuterium transfer in the photoenolization of triplet 1,4-dimethyl-10H-anthracen-9-one (1) with varying degrees of deuterium label in their methyl groups (1-d3, 1-d2, and 1-d) have been investigated as a function of temperature between 5 and 77 K. Measurable rate constants in the case of 1-d3 and 1-d2 were used to construct Arrhenius plots which illustrate the expected curvature and leveling off of rate constant versus temperature. The difference in tunneling rate constants of 1-d3 and 1-d2 yields a tunneling isotope effect, TIE = 2.4, which is attributed to the secondary alpha isotopic substitution. Density functional theory (DFT, B3LYP/6-31G*) calculations were carried out to obtain structural and energetic information for the H(D) transfer along the triplet state zero-point energy levels. The temperature dependence of the rate constants for each isotopologue was simulated with a model that considers the frequency of the C-D stretching mode and the quantum mechanical permeability determined from calculated energy parameters. The model suggests that a difference in barrier width of only 0.015 A between 1-d3 and 1-d2 leads to the observed 2-fold difference between tunneling rates.     

Enantiomeric separation of racemic neolignans on chiralcel OD and determination of their absolute configuration with online circular dichroism

Effective enantiomeric separations of erythro- and threo-8.O.4'-neolignans with different aromatic substitution pattern (1a-i, 2a-i) are achieved on the commercially available chiral stationary phase cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD). It is shown that the chiral recognition of the stationary phase is significantly dependent on the substitution pattern of the racemic compounds. Online liquid chromatography (LC)-circular dichroism (CD) analysis allows for the establishment of a correlation between the absolute configuration of the separated erythro-8.O.4'-neolignans and their characteristic CD transitions, which could be used to determine or revise the configuration of previously isolated erythro-8.O.4'-neolignans. Although the absolute configurations of threo-isomers is not determined unambiguously from the LC-CD analysis, it is proven that both their elution order and chiroptical properties are significantly influenced by the substitution pattern of the aromatic rings.     

Normal Raman and surface enhanced Raman spectroscopic experiments with thin layer chromatography spots of essential amino acids using different laser excitation sources

A comparative study of the feasibility and efficiency of Raman spectroscopic detection of thin layer chromatography (TLC) spots of some weak Raman scatterers (essential amino acids, namely, glycine and L-forms of alanine, serine, valine, proline, hydroxyproline, and phenylalanine) was carried out using four different visible and near-infrared (NIR) laser radiations with wavelengths of 532, 633, 785, and 1064 nm. Three types of commercial TLC plates were tested and the possibility of inducing surface enhanced Raman scattering (SERS) by means of Ag-sol was also investigated. The spectra obtained from spotted analytes adsorbed on TLC plates were of very different quality strongly depending on the excitation wavelength, the wetness of the samples, and the compounds examined. The best results were obtained with the simple silica TLC plate, and it has been established that the longest wavelength (lowest energy) NIR excitation of a Nd:YAG laser is definitely more suitable for generating normal Raman scattering of analyte spots than any of the visible radiations. Concerning SERS with application of Ag-sol to the TLC spots, 1-3 orders of magnitude enhancement was observed with wet samples, the greatest with the 532 nm radiation and gradually smaller with the longer wavelength excitations. It is shown, however, that due to severe adsorption-induced spectral distortions and increased sensitivity to microscopic inhomogeneity of the sample, none of the SERS spectra obtained with the dispersive Raman microscope operating in the visible region were superior to the best NIR normal FT-Raman spectra, as far as sample identification is concerned.     

Influence of the Phase Morphology on the Viscoelastic Behaviour of Polymer Blends (PP-EPR)

Summary. Melts of polyethylene-propylene-rubber (EPR, blends of linear polyethylene, linear polypropylene, and PE-PP copolymer) show phase separation. The influence of the phase morphology on the viscoelastic behaviour is studied with the aid of the dynamical moduli. The measured moduli of the fraction of the linear homopolymer of an EPR agree with the moduli calculated from the molar mass distribution of this fraction. In contrast, the copolymer fraction shows a strong rubber-like behaviour (represented by a characteristic relaxation time spectrum). Mixtures of 80 wt% linear PP and of EPRs with low copolymer content are not rubber-like liquids. In addition, the moduli from them can be calculated from the moduli of the components with the aid of Palierne’s emulsion model. This clearly reveals that the linear PP forms the matrix in this case. Mixtures of 80 wt% linear PP and of EPRs with high copolymer content show rubber-like behaviour and Palierne’s emulsion model is not applicable on them. Obviously, the copolymer fraction forms a physical network.     

Consecutive Reactions Observed Using Floated Collision Cells

Sequential processes occurring in one field-free region of a sector-type mass spectrometer were observed by floating the collision cell. This way four overall processes were identified; (a) both processes occurring outside the cell, (b) both processes inside the cell, (c) the first process outside and the second inside, and (d) the first inside, the second outside the cell. Positions of these peaks are derived and several examples are shown (for CsI clusters, benzophenone and nitrobenzene). This is a unique technique for distinguishing sequential and one-step processes like the (sequential) loss of two monomers and loss of a dimer from a supramolecular cluster.     

Synthesis and fragmentation of new 2‐phosphabicyclo[2.2.2]octene 2‐oxides

The substitution pattern of the 2‐phosphabicyclo[2.2.2]octene framework and the skeleton itself were varied to obtain new cycloadducts usable in phosphorylations and to study their ability to undergo fragmentation. Thus, an N‐methyl and several P‐trialkylphenyl derivatives ( 7 and 9 , respectively) were synthesized, together with two diaza species ( 8 ) whose stereostructure was evaluated by single crystal X‐ray analysis. Mechanistic studies on the UV light‐mediated photolysis of the P‐aryl phosphabicyclooctenes ( 9 ) in the presence of methanol supports the suggestion of a novel addition–elimination reaction path. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:626–632, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10052     

Determination of LogP for Biologically Active Chalcones and Cyclic Chalcone Analogs by RPTLC

JPC – Journal of Planar Chromatography – Modern TLC - LogP values of 41 biologically active chalcones (Figure 1, 1) and their cyclic analogs, E-2-(X-benzylidene)-1-indanones (Figure 1,...     

Modification of D‐glucose‐based 18‐crown‐6 ethers by phosphorylation and phosphinylation

The primary hydroxy groups of head‐tail and head‐head bis(sugar)‐based crown ethers ( 1 and 3 , respectively) were acylated by (EtO)₂P(O)Cl and Ph₂P(O)Cl in a selective manner. Cation binding ability of the bis‐phosphorylated and phosphinylated macrocycles ( 2 and 4 ) was evaluated by the picrate extraction method. Introduction of the P‐moieties led to increase of the extraction ability without significant selectivity. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:267–270, 2000     

Influence of surface chemistry on the SAXS response of polymer-based activated carbons

Small-angle X-ray scattering (SAXS) measurements using contrast variation are reported for activated carbons prepared from poly(ethyleneterephthalate). The carbon surfaces are functionalized to different degrees by cold and hot nitric acid treatment. The latter treatment reduces the surface area by 75%, but the pore size distribution in the micropore range is hardly affected. Seven liquids, n-hexane, i-octane, i-propanol, cyclohexane, toluene, alpha-pinene, and nitrobenzene, in addition to water vapor, were used as contrast modifiers. Although the values of the specific surface area S(X) deduced from these measurements are relatively insensitive to the solvent, the detailed SAXS spectra reveal interactions occurring on different spatial scales that depend on the surface chemistry of the carbon and on the physicochemical properties of the solvent. In the most heavily oxidized sample, the amphiphilic molecule i-propanol stabilizes the surface structure, whereas nonpolar molecules make the rough surface smoother. In the untreated and the lightly functionalized carbons, water vapor at 50% relative humidity condenses only partially in the micropores at room temperature, whereas in the heavily treated sample condensation in the micropores is practically complete.