Search results for "Thin layer"

New reagent for the detection of sesquiterpene lactones by thin-layer chromatography.

1984

Deposition and production of highly reproducible hybrid Cu[(tBu)4Pc]-polystyrene thin layers via spin casting

2012

This study focuses on the determination of a protocol for the production of a hybrid material composed of a polymer and a macrocyclic complex, namely polystyrene and a tetra-tert-butyl-copper phthalocyanine (Cu[(tBu)4Pc]), in order to obtain a layer thickness of about 100 nm and a controlled porosity in a highly reproducible way. Several methods were implemented and their reproducibility was evaluated through elements of characterization such as optical microscopy, atomic force microscopy and scanning electron microscopy. POLYM. ENG. SCI. 2013. © 2012 Society of Plastics Engineers

Orientation of Polymer Functionalized Nanorods in Thin Films

2010

A directed self assembly of anisotropic nanostructures offers a possibility to provide unique functional materials, which are e.g., important in optoelectronic devices. We use the liquid crystalline behavior of polymer functionalized TiO2 and ZnO nanorods to apply methods well known for low molecular liquid crystals to achieve oriented thin films. Convective forces in the meniscus on a structured substrate obtain thin layers of oriented nanoparticles with a ordering parameter of S = 0.7. As another method we present the orientation of polystyrene covered ZnO nanorods under an applied electric field. The method offers a perpendicular alignment of the rods to the surface.

Use of two-dimensional thin-layer chromatography for the components study of poly(adenosine diphosphate ribose)

1990

Two-dimensional thin-layer chromatography on cellulose plates has been used for separating and quantifying the three adenosine derivatives: AMP, phosphoribosyl AMP (PRAMP), and (PR)2AMP obtained by venom phosphodiesterase digestion of poly(ADP-ribose). In vitro synthesized polymer, up to 300 derivatives in length were studied. Some parameters of the complexity of poly(ADP-ribose) could be deduced from our results: (i) The first branching point appears in fragments of approximately 21 derivatives in length. (ii) The branching points are located at regular distances of approximately 41 derivatives from each other.

Effects of VTE Treatment on Composition of Lithium Tantalate Single Crystals

2011

The vapour transport equilibration (VTE) is used to change the Li/Ta ratio in lithium tantalate single crystals of different crystallographic orientations (Z-cut and Y/128°-cut). Treatment by VTE is shown to provide thin layers in lithium tantalate plates composition of which is close to stoichiometric while the values of the coercive field are different, much smaller compared with congruent single crystals. There are several mechanisms of diffusion of the Li+ ions in LiTaO3 under conditions of VTE the contribution of each being dependent on the crystallographic orientation of the sample.

Protection of iron-based alloys likely to be exposed to corrosive atmospheres

1998

Summary This study examines the influence of temperature on oxidation kinetics of the alloys Z2CT 17 and Z4CN 18-09. A thin layer of aluminium oxide was laid down on these, using chemical, vapor deposition, in order to give improved protection.

The bleaching efficacy of carbamide peroxide gels containing potassium nitrate desensitizer

2020

Background To evaluate the bleaching efficacy of at-home carbamide peroxide (CP) gels in two concentrations, containing or not a desensitizing agent. Material and methods Forty incisors were divided into four groups (n=10), according to gel concentrations (10% or 22%), and presence or not of 3% potassium nitrate in the gel. A thin layer of gel was applied to the buccal surface of each tooth for 2h/day for 4 weeks. Bleaching efficacy was measured using a spectrophotometer, and ∆E*ab, ∆E00 and ∆WID were calculated. Measurements were performed at baseline, 7, 14, 21, 28, and 35 days following the first gel application. Data were analyzed by two-way RM-ANOVA and Tukey's test (α=0.05). Results R…

Optimising Lactic Acid Cheese Packaging Systems

2016

On the basis of a previous research, it seems that foil-wrapped tray solutions are not particularly chosen by lactic acid cheese consumers. With relation to this study, almost half of the respondent population would have expressed the desire of different packages. Parchment packages and poly(ethylene-co-vinyl acetate)/polyvinylidene chloride/poly(ethylene-co-vinyl acetate) laminates would be removed by 25.0 and 12.5% of customers, respectively. Polyamide/polyethylene double and single packaging would be removed from the market only by 5.0% of respondents. Data have shown that cheese and packaging quality are dependent on lactic acid cheese surface microflora. The type of this microflora is …

Degradation of an alkaloid pheromone from the pale-brown chafer, Phyllopertha diversa (Coleoptera: Scarabaeidae), by an insect olfactory cytochrome P…

1999

AbstractThe pale-brown chafer, Phyllopertha diversa, utilizes an unusual alkaloid, 1,3-dimethyl-2,4-(1H,3H)-quinazolinedione, as its sex pheromone. This compound is rapidly degraded in vitro by the antennal protein extracts from this scarab beetle. Demethylation at the N-1 position and hydroxylation of the aromatic ring have been identified as the major catabolic pathways. The enzyme responsible for the pheromone degradation is membrane-bound, requires NAD(P)H for activity and is sensitive to cytochrome P450 inhibitors, such as proadifen and metyrapone. The ability to metabolize this unusual pheromone was not detected in 12 species tested, indicating that the P450 system, specific to male P…

Development of high-performance thin layer chromatography method for identification of phenolic compounds and quantification of rosmarinic acid conte…

2020

ABSTRACT Aim: Representatives of Nepetoideae Burnett subfamily are promising species of the Lamiaceae Martinov family because of accumulating such valuable groups of secondary metabolites as terpenoids and polyphenols. A high-performance thin layer chromatography (HPTLC) fingerprint method for the qualitative determination of phenolic compounds and for the quantification of rosmarinic acid (RA) content in methanol extracts of five species of this subfamily was developed for the first time. Materials and Methods: Dried aerial parts of Dracocephalum moldavica L., Ocimum americanum L., Lophanthus anisatus (Nutt.) Benth., Monarda fistulosa L., and Satureja hortensis L. collected in flowering pe…