Liquid chromatography/mass spectrometry and liquid chromatography/nuclear magnetic resonance as complementary analytical techniques for unambiguous identification of polymethoxylated flavones in residues from molecular distillation of orange peel oils (Citrus sinensis)

Liquid chromatography/mass spectrometry and liquid chromatography/nuclear magnetic resonance techniques with ultraviolet/diode array detection were used as complementary analytical tools for the reliable identification of polymethoxylated flavones in residues from molecular distillation of cold-pressed peel oils of Citrus sinensis. After development of a liquid chromatographic separation procedure, the presence of several polymethoxy flavones such as sinensetin, nobiletin, tangeretin, quercetogetin, heptamethoxyflavone, and other derivatives was unambiguously confirmed. In addition, proceranone, an acetylated tetranortriterpenoid with limonoid structure, was identified for the first time in citrus.     

Rates of foliar penetration of chelated Fe(III): role of light, stomata, species, and leaf age

Rates of foliar penetration of Fe(III) chelates of imidodisuccinic acid (IDHA), ligninsulfonic acid (Natrel), and citric acid (ammonium ferric citrate) were studied at 20 degrees C using a leaf disk method. After drying of the donor droplets, the humidity over the donor residues was maintained at 100% because Fe(III) chelates deliquesce only when humidity is higher than 90%. The wetting agent Glucopon 215 CSUP was added at a concentration of 0.2 g L(-1) to all donor solutions. With fully expanded stomatous broad bean leaves, penetration of Fe-IDHA followed first-order kinetics and rate constants of penetration were higher in light (0.073 h(-1)) than in the dark (0.042 h(-1)). Permeability of broad been leaves to CaCl2 was about 8 times higher than to Fe-IDHA. Doubling the Fe-IDHA concentration in the donor from 2.5 to 5 mmol L(-1) decreased rate constants of Fe-IDHA penetration by a factor of 2.2. Adding the silicon surfactant Break Thru S240 at 10 g L(-1) to the donor induced infiltration of open stomata and about 80% of the applied Fe-IDHA penetrated during droplet drying, while with Glucopon 215 CSUP stomatal infiltration was not observed. With broad bean leaves, penetration of Natrel and ammonium ferric citrate also followed first-order kinetics and rate constants were also higher in light than in the dark. Adaxial astomatous surfaces of fully expanded pear, apple, and grapevine leaves were practically impermeable to Fe-IDHA while stomatous abaxial leaf surfaces were permeable, but rate constants of penetration decreased with time and differed greatly among species. Astomatous surfaces of young unfurling grapevine and peach leaves were permeable to Fe-IDHA, but permeability of stomatous surfaces was much higher. The effect of light on permeability of stomatous leaf surfaces is attributed to the presence of aqueous pores in cuticles over guard cells, and it is suggested that permeability of these pores increases as stomata open. Consequences of these results for foliar applications of Fe chelates are discussed.     

A 2D quantum walk simulation of two-particle dynamics

Multidimensional quantum walks can exhibit highly nontrivial topological structure, providing a powerful tool for simulating quantum information and transport systems. We present a flexible implementation of a two-dimensional (2D) optical quantum walk on a lattice, demonstrating a scalable quantum walk on a nontrivial graph structure. We realized a coherent quantum walk over 12 steps and 169 positions by using an optical fiber network. With our broad spectrum of quantum coins, we were able to simulate the creation of entanglement in bipartite systems with conditioned interactions. Introducing dynamic control allowed for the investigation of effects such as strong nonlinearities or two-particle scattering. Our results illustrate the potential of quantum walks as a route for simulating and understanding complex quantum systems.     

Effect of bandaging on second intention healing of wounds of the distal limb in horses

Objective   To evaluate the effect of a non-occlusive dressing incorporated in a 3-layer bandage on second intention healing of wounds of the distal portion of the limb.
Study Design   Untreated wounds in 33 adult horses used in four studies using the same wound-healing model conducted over 5 years.
Methods   Standardised, full-thickness wounds were made in the skin overlying the dorsomedial aspect of the mid-metacarpus; 17 horses were bandaged with a non-occlusive dressing covered by gauze-coated cotton wool that was compressed with adhesive tape; 16 horses were left unbandaged. Wounds were photographed weekly for 9 weeks and the images were analysed electronically.
Results   There were significant effects associated with bandage (P < 0.0001), week (P < 0.001), and bandage by week interaction (P < 0.0001). There was no difference in wound area at the first time-point after wound creation (P = 0.38). After week 1, there was a difference between bandaged and unbandaged wounds in wound area at each measurement until the end of the study. Bandaged wounds showed greater and more prolonged retraction. Unbandaged wounds retracted for 2 weeks before beginning to contract, whereas bandaged wounds continued to retract for 3 weeks. In bandaged wounds excess granulation tissue required regular trimming, but not in unbandaged wounds. There was no difference between groups in the total days to healing or the overall rate of healing.
Conclusions   These results should be treated with caution until validated with contemporaneous, controlled studies. Covering a wound with a non-occlusive dressing in a 3-layer bandage led to greater wound retraction, modulated the rate of wound contraction and promoted excessive granulation tissue. If excessive granulation tissue is excised regularly, bandaging has no effect on total time to healing.     

Mobilities of organic compounds in reconstituted cuticular wax of barley leaves: Determination of diffusion coefficients

Isolated cuticular wax, obtained from barley leaves, was mixed with ¹⁴Clabelled organic chemicals including aromatic pesticides and long-chain linear alkanes, alcohols and acids. These mixtures were reconstituted from the melt and labelled chemicals were desorbed from the wax by immersing the wax samples in aqueous phospholipid suspensions. Diffusion coefficients (D) of radiolabelled test compounds in the wax were derived from desorption kinetics. Diffusion coefficients ranged from 10^?17 to 10^?22 m² s^?1 and decreased rapidly with increasing molar volumes of solutes. However, size selectivity of D was much more pronounced with the linear, long-chain molecules than with the aromatic compounds. It is argued that the two different groups of chemicals (compounds occurring naturally in cuticular waxes vs pesticide molecules) were trapped in different fractions of wax during crystallization from the melt. The normal long-chain aliphatic compounds appear to be incorporated into the crystalline fraction of the wax, while the cyclic pesticide molecules are confined to the solid amorphous regions. Our data indicate that constituents of cuticular waxes are not immobile. In fact, relatively small linear aliphatic molecules have mobilities that do not differ too much from those of cyclic pesticides. However, the pronounced size selectivity of diffusivities of long-chain aliphatic compounds causes a rapid decrease in D with increasing chain length. The value of D of hexadecanoic acid was 3.81 × 10^?18 m² s^?1 while that of dotriacontane was only 4.07 × 10^?22 m² s^?1. Thus, increasing the carbon number by a factor of two resulted in a decrease in mobility by almost four orders of magnitude. Diffusivities of selected pesticide molecules in reconstituted wax were compared with permeances measured using intact barley leaves and were found to be in satisfactory agreement.     

Metabolism of amitrole in apple: II. Bound residues from mature fruits

Significant radioactivity detected in mature fruits, harvested from apple trees (Malus domestica Borkh., cv. ‘Golden Delicious’ and ‘Gloster’) that were soiltreated with [3,5-¹⁴C]amitrole, remained in the insoluble plant material after exhaustive extraction. These bound residues were solubilized with a mixture of pectinases and cellulases. Thus, separation and characterization of carbohydrates and xenobiotic moieties released during this procedure became possible. A part of the radiolabel was incorporated into natural products, indicating degradation of the applied amitrole and reassimilation of [¹⁴C] carbon dioxide.     

Metabolism of amitrole in apple: III. Model systems

Excised shoots from apple trees and cell suspension cultures were used as model systems to study the metabolism of [3,5-¹⁴C]amitrole in Malus domestica Borkh. Significant differences in the metabolism of the compound applied were observed with excised shoots, cultured cells and whole apple trees. The major metabolite in excised shoots was aminotriazolylalanine which occurred both in the free form and as conjugates. The major metabolite from whole plants. triazolylalanine, was detected in shoots in minor amounts only. In cell suspension cultures, the type of metabolism strongly depended on the concentration of amitrole when initially applied. At 10 ^?3 m or lower, mainly aminotriazolylalanine was formed. Depending on the concentration of the active ingredient, this metabolite predominantly occurred in free form or as glycosides. At concentrations above 5 × 10^?4 M a new metabolite, 3,5-dihydroxytriazole, was detected which was the only metabolite found at 5 × 10^?3M. Significant amounts of nonmetabolized amitrole remained in the medium.     

From knowing to controlling: a path from genomics to drugs using small molecule probes

The National Cancer Institute Initiative in Chemical Genetics is designed to encourage the development of small molecular probes. The probes are useful for activating or inactivating protein functions, thereby providing resources that help discern the functions of gene products in normal and disease cells, as well as in tissues. This initiative includes "ChemBank," a suite of informatics tools and databases aimed at promoting the development and use of chemical genetics by scientists worldwide. The information generated with such tools should provide a critical link from genomic discovery to drug development.