Search results for "composition"

Surface and bulk ordering in thin films of a symmetrical diblock copolymer

2013

Amphiphilic diblock copolymers have the ability to adapt their surface's molecular composition to the hydrophilicity of their environment. In the case of about equal volume fractions of the two polymer blocks, the bulk of these polymers is known to develop a laminar ordering. We report here our investigation of the relationship between bulk ordering and surface morphology/chemical composition in thin films of such an amphiphilic diblock copolymer. Upon annealing in vacuum, the expected lamella ordering in the bulk of the film is observed and we find the morphology of the film surface to be defined by the thickness of the as-deposited film: If the as-deposited thickness matches the height of…

Determination of albendazole and ivermectin residues in cattle and poultry-derived samples from India by micellar liquid chromatography

2021

We have developed a method, based on micellar liquid chromatography, to determine albendazole and ivermectin in dairy products and biological waste from bovine, as well as edible tissues from poultry. Anthelmitics were resolved in less than 10 min using a C18 column and a mobile phase of 0.15 mol/L sodium dodecyl sulfate – 6% 1-pentanol at buffered at pH 7 with a 0.01 M phosphate salt, running under isocratic mode at 1 mL/min. Detection was by absorbance at 292 nm. Method was successfully validated following official validation guidelines, in terms of: selectivity, sensitivity, calibration range (0.0125−0.5 mg/kg to 25−50 mg/kg), linearity (r2 > 9990), trueness (86.3–105.6%), precision (<12…

Cardenolides of Digitalis obscura: The effect of phosphate and manganese on growth and productivity of shoot-tip cultures

1997

Abstract Cardenolide composition of leaves from wild and micropropagated elite plants of Digitalis obscura (genotype T4) has been investigated and no qualitative differences were found among their major cardenolides (series A). All of the detected glycosides belong to the digitoxose-type cardenolides. Genins represented less than 2% of the overall content, while lanatoside A was the predominant cardenolide ( ca. 65%) in all samples. The cardenolide yield of micropropagated D. obscura plants depended on the age and development of the cultures, but productivity of long-term cultures (2 years) was quite similar to that of the parent plant. Changes in the concentrations of phosphate or manganes…

Analysis of the proteins involved in the structure and synthesis of the cell wall of Ustilago maydis

2008

Abstract A study of the proteins involved in the synthesis and structure of the cell wall of Ustilago maydis was made by in silico analysis of the fungal genome, with reference to supporting experimental evidence. The composition of the cell wall of U. maydis shows similarities with the structural composition of the walls of Ascomycetes, but also shows important differential features. Accordingly, the enzymes involved in the synthesis of the U. maydis wall polysaccharides chitin and β-1,6 glucans displayed some differential characteristics. The most salient difference in protein composition was the predicted absence of Pir proteins, an important class of proteins present in the Ascomycetes.…

Decomposition of organic matter with molten alkali: determination of arsenic and antimony in organic compounds

1982

Decomposition of organic matter with molten alkali has been examined as a method of opening out organic matrices for elemental detection and/or determination. The fusion product is readily soluble. Arsenic and antimony in organic compounds can be determined iodimetrically after mineralization by this fusion method.

Synthesis, optical, and thermal properties of glassy trityl group containing luminescent derivatives of 2-tert-butyl-6-methyl-4H-pyran-4-one

2012

In this work we present simple preparation of original trityl group containing glassy luminescent 6-styryl substituted derivatives of 2-(2-tert-butyl-4H-pyran-4-ylidene)malononitrile (DWK-1TB), 2-(2-tert-butyl-4H-pyran-4-ylidene)-2- ethyl-2-cyanoacetate (KWK-1TB), 2-(2-tert-butyl-4H-pyran-4-ylidene)-1H-indene-1,3(2H)-dione (ZWK-1TB) and 5-(2-tert-butyl-4H-pyran-4-ylidene)pyrimidine-2,4,6(1H,3H,5H)-trione (JWK-1TB). Their optical properties have been investigated. The absorption maxima of synthesized glasses is in region from 425 nm to 515 nm and emission maxima is from 470 nm to 625 nm in solution of dichloromethane. But absorption maxima of their solid films is from 425 nm to 500 nm and em…

1986

In order to graft methacrylonitrile onto preformed networks containing thermolabile azo groups, the monomer was used to swell the networks and then the temperature raised to the decomposition temperature for the azo groups. The unusually high grafting efficiencies yields (e) achieved are explained in terms of both the differences in the reactivities of the primary radicals formed and side reactions, which lead to additional grafting sites. As an aid to understand the dependence of monomer conversion on that of the initiator a kinetic model is discussed, which involves the consideration of the polymerization taking place both in the homogeneous phase and within the polymer pearls, which can …

Thermal and optical properties of 4H-pyran-4-ylidene fragment and bis-styryl and triphenyl groups containing derivatives

2014

Small D-π-A type organic molecules with incorporated 4H-pyan-4-ylidene (pyranylidene) fragment in their structures show potential in organic photonics - such as materials for organic light emitting diode application studies and organic solid state lasers. Additional incorporation of bulky triphenyl- groups in their structures gives them the ability to form thin amorphous solid films from volatile non-polar organic solvents. Unfortunately, there is still no clear relation between compound organic structures and their thermal and optical properties. In order to investigate the above mentioned regularities we have synthesized a series of tripheyl- group containing derivates of 2,6-bis-styryl-4…

Separation of aromatic aminophosphonic acid enantiomers by capillary electrophoresis with the application of cyclodextrins

2002

The detailed studies concerning capillary electrophoresis separation of aminophosphonic acid enantiomers with various commercially available cyclodextrins are presented. The obtained results show that the separation of these stereoisomers is dependent on pH of background electrolyte, concentration of cyclodextrin as well as on the type of applied chiral selector. The separation mechanism is based on the co-operative effect of hydrogen bond type interactions enhanced by hydrophobic forces and sterical constrains between aminophosphonate and cyclodextrin. With application of elaborated method, enantiomeric baseline or partial separation of 18 alpha-aminophosphonic acids was achieved. This sep…

Fatty acid composition of the seed lipids ofChamaerops humilisL. natural populations and its relation with the environment

2014

Seed lipids composition is a tool to discriminate among plant taxa and is related to phylogeny and biogeographic distribution. Aim of the present study was to evaluate the fatty acid (FA) composition of the seed lipids from nine natural Chamaerops humilis L. population and its relation with the climatic traits of the collection sites. The average seed lipids content was 54.8 g kg21 and the most represented FAs were oleic (478 g kg21 oil) and linoleic (230 g kg21 oil), with significant differences among the accessions. Most of the lipid traits significantly correlated with climatic traits. In particular, oleic acid negatively correlated with year potential evapotranspiration. These relations…