Viera Jančovičová - Academia.edu (original) (raw)

Papers by Viera Jančovičová

Fibres & Textiles in Eastern Europe

Every manufacturer wants to protect their textile products and their brand. A possible solution i... more Every manufacturer wants to protect their textile products and their brand. A possible solution is, for example, the insertion of fibres with special pigments visible under irradiation by UV light into the final product. The paper focused on the study of the structure and colourimetric properties of polypropylene (PP) and poly-(lactic) acid (PLA) fibres modified with photoluminescent dye and halloysite (HNT) modified with photoluminescent dye. The photoluminescent dye and HNT modified with photoluminescent dye affected the structure of PP and PLA fibres differently. Increasing the HNT content up to 0.15 % increased the orientation of the PP fibres. In the case of PLA fibres, the increased content of photoluminescent dye in PLA fibres increased their orientation in the observed concentration area. PLA-based knitted fabrics showed better light stability, where there was no visible degradation of the knitted fabric, only its darkening. Likewise, PLA-based knitted fabric showed luminesc...

Dyes and Pigments, Feb 1, 2021

Abstract Carminic acid is the main coloring component of cochineal (a red organic dye extracted f... more Abstract Carminic acid is the main coloring component of cochineal (a red organic dye extracted from female bodies of Dactylopius coccus). The utilization of the dye in specific painting techniques is determined by the addition of suitable binders, which influence the light and thermal stability of the color layer. In this work, the influence of some plant-based binders (maize starch, gum arabic) and some binders of animal origin (egg albumen, gelatin) on light and thermal stability of model systems with carminic acid was studied. As colorants, two available commercial colorants were used – the carminic acid and Carmine Naccarat, and two colorants prepared in the laboratory – the cochineal carmine and cochineal. The color layers were subjected to accelerated light and thermal aging. For characterization of the color layers and changes of their properties during accelerated aging the spectral methods (ATR-FTIR, VIS) and colorimetry were used. Comparison of the influence of the binders on light stability of the color layers showed the layers with albumen were the least stable, whereas the layers with gum arabic were the most stable. No significant color changes were detected during thermal aging.

Journal of Photochemistry and Photobiology A-chemistry, Sep 1, 2000

The photodecomposition of commercial lipophilic diaryliodonium hexafluoroantimonate SarCat ® SR-1... more The photodecomposition of commercial lipophilic diaryliodonium hexafluoroantimonate SarCat ® SR-1012 was investigated in acetonitrile (ACN) and ACN/H 2 O mixed solvents by means of UV/Vis spectroscopy, an EPR in situ spin trapping technique and GC/MS analysis. The application of the spin traps nitrosodurene (ND) and 5,5-dimethyl-1-pyrroline N-oxide gave evidence for the production of radical intermediates corresponding to the breaking of the carbon-iodine bond, in addition to carbon-oxygen bonds in SR-1012 aryl substitution. The photolytic products analyzed in aprotic acetonitrile were iodobenzene, acetanilide, biphenyl and C 12 H 25 CH(OH)CH 3 , while in ACN/H 2 O (1:1, vol.) solution iodobenzene, biphenyl, C 12 H 25 CH(OH)CH 2 OC 6 H 4 OH and hydroxylated biphenyls were identified. The influence of oxygen on the product distribution in both solvent systems was inconsequential. The proton concentrations photogenerated in the irradiated SR-1012 ACN/H 2 O solutions were quantified spectrophotometrically using bromophenol blue indicator.

Journal of Molecular Catalysis A-chemical, Mar 1, 2000

Ž. Ž. The decomposition of sodium anthracene-1-sulfonate AN1S by irradiation l) 300 nm was invest... more Ž. Ž. The decomposition of sodium anthracene-1-sulfonate AN1S by irradiation l) 300 nm was investigated in oxygensaturated aqueous solutions and TiO suspensions. The concentration decrease of AN1S during exposure follows the formal 2 first-order kinetics. The formation of phthalic and salicylic acids was monitored by high performance liquid chromatography Ž. HPLC in both photosystems. Additionally, the formation of alizarin during irradiation in the presence of TiO was 2 Ž. confirmed. The effect of experimental conditions initial AN1S concentration, pH value, TiO concentration on the formal 2 initial rate of AN1S photodegradation was studied in details. In situ EPR spin trapping experiments in TiO suspensions 2 Ž. confirmed the competitive reaction of photogenerated hydroxyl radicals between 5,5-dimethyl-1-pyrroline N-oxide DMPO spin trap and AN1S.

Journal of Cultural Heritage, Jul 1, 2014

Moist heat (100 • C in closed vessels) and pollutants (SO 2 or NO x , 100 • C) techniques of acce... more Moist heat (100 • C in closed vessels) and pollutants (SO 2 or NO x , 100 • C) techniques of accelerated ageing were applied in stability investigation of iron gall inks on parchment. The measured characteristics on parchment samples coated with inks (made of iron(II) sulfate and gallic acid or tannic acid in various ratios) reflected their chemical, optical and spectroscopic attributes. Decrease of surface pH values was measured for all samples, especially after ageing with SO 2. The results obtained, comparing the non-aged samples with those aged upon heat and pollutants, revealed the decrease of lightness L* and the increase of chromatic coordinate b* for all six ink layers. These differences in b* were dominantly reflected in values of total color difference (E * ab , CIE L*a*b*). The variations in UV/VIS reflectance spectra and E * ab evidenced the considerable damage of inks exposed to accelerated ageing, especially for inks prepared with excess of acid to iron. FTIR spectroscopic measurements of parchment showed that accelerated ageing procedures caused changes in structure and arrangement of collagen, and the formation of oxidation products in parchment during the accelerated ageing was stimulated by presence of inks. EPR spectra of parchment coated with inks showed the paramagnetic signals of various Fe(III) species ions in different coordination.

Dyes and Pigments, Sep 1, 2016

Abstract The spectroscopic study was performed on 9,10-anthraquinone derivatives (purpurin, aliza... more Abstract The spectroscopic study was performed on 9,10-anthraquinone derivatives (purpurin, alizarin, carminic acid, and 2-(hydroxymethyl)-9,10-anthraquinone) in dimethylsulfoxide in the presence of triethylamine to bring information on their protonation/deprotonation equilibria in aprotic solvent. An interesting deprotonation effect of 5,5-dimethyl-1-pyrroline N -oxide (a spin trapping agent used in the EPR experiments) was revealed. The quantum chemical calculations enabled the identification of the individual protonated/deprotonated tautomeric forms present in the experimental systems. The UV photoexcitation of hydroxyanthraquinones (HAQ) led to the generation of reactive radical species and singlet oxygen, detected by in situ EPR spectroscopy (spin trapping, nitroxide radical elimination, oxidation of sterically hindered amines). The changes in the electronic absorption spectra upon photoexcitation, linked with the ability of the studied HAQ to generate reactive oxygen species upon exposure, confirm a substantial effect of the substituent character and position on the overall photochemical behavior of the HAQ, significantly influenced by the actual experimental conditions (solvent, pH).

Restaurator-international Journal for The Preservation of Library and Archival Material, Jan 23, 2006

Arylmethane dyes represent one of the oldest man-made dyestuffs. Primarily, Fuchsin and Methyl Vi... more Arylmethane dyes represent one of the oldest man-made dyestuffs. Primarily, Fuchsin and Methyl Violet were manufactured at the end of the 19 th century. A milestone in the synthesis of arylmethane dyestuffs was the discovery by Michler in 1867 of the reaction of phosgene with dimethylaniline. Based on this reaction, Caro and Kern prepared Crystal Violet in 1883. Fischer described, in 1877, the process of preparing Malachite Green, which is still employed on an industrial scale today 1. Later, other types of arylmethane dyes were prepared. on the basis of hydroxyl triphenyl methane and xanthene compounds, and additionally acidic triphenylmethane dyes obtained by sulphonation of basic dyestuffs. Arylmethane dyestuffs have great commercial significance despite some of their drawbacks which include low light stability 2. In particularly, Crystal Violet, Malachite Green, Auramine and Rhodamine B are used extensively. Xanthene dyes represent the fundamental constituents of writing inks, further they are used for painting on wood and paper and in cosmetic preparations. Some types of arylmethane dyes are applied mainly in the printing and graphic industry and are also used for medical purposes. Other dyes are employed in the food industry and for the manufacture of pigments 2. Light stability of dyes is given by two parallel reactions: free radical generation and the interaction of generated radicals and reactive intermediales with the dye molecule. Reactive radicals are responsible for the actual degradation of dyestuffs, consequently their generation provides problems with archive documents, when arylmethane dyes are used for writing or design 3, 4. Irreversible photodegradation processes can be classified as photo-oxidations and photoreductions. The key factor influencing the type of degradation reaction is the chemical structure of the dye. On the other hand, there are many other aspects which can affect the course and rate of the decomposition reaction. They include the type of matrix carrying the dye, the type of solvent, the dye concen

Conductive polymer materials replace standard used metal materials to obtain lightweight material... more Conductive polymer materials replace standard used metal materials to obtain lightweight material, cheaper material, transparent material, ecological material and still electrically conductive materials. In this work was used conductive polymer polypyrolle prepared by oxidative polymerization in water solution of dodecylbenzylsulfonate acid with AgNO3. Polypyrolle can be used as a conductive additive to prevent of static electricity (electromagnetic shield) or as a component of photovoltaic cells. Homogenous layer of polypyrolle was deposited on different substrates using ink-jet printing technology and other coating technologies. Special test chart was used for printing. Paper substrates with varnishing and PET foil were used. Conductivity of printed substrates was measured to evaluate polymer layer quality.

Progress in Colloid & Polymer Science

The diffusion process of polymer dissolution in liquid solvents and the kinetics of the surface s... more The diffusion process of polymer dissolution in liquid solvents and the kinetics of the surface swollen layer formation have been studied. The following fundamental kinetic paraeters of the dissolution and swelling processes have been presented: the rate of dissolution u OC and its relevant thermodynamic and kinetic parameters (ΔH d ≠ and ΔH D,d ≠ ); the induction period of

Chemical Papers, 2007

Polymerization kinetics and gloss of different formulations of coatings at different UV curing co... more Polymerization kinetics and gloss of different formulations of coatings at different UV curing conditions were studied. The results showed that the photoinitiator type, its concentration, sample coating thickness, as well as the UV light intensity were the most significant factors affecting the polymerization course and the gloss of UV-cured films. The increasing concentration of the photoinitiator and the UV light intensity significantly decreased the gloss of the cured surface. The influence of the sample coating thickness on the kinetics and final gloss was also considerable.

(1) Teeth, represent in humans the most resilient tissues. However, exposure to concentrated acid... more (1) Teeth, represent in humans the most resilient tissues. However, exposure to concentrated acids might lead to their obliteration, thus making human identification difficult. Teeth often contain dental restorations from materials that are even more resilient to acid impact. This paper introduces novel method of 3D reconstruction of dental patterns as a crucial step for digital identification with dental records.; (2) With combination of modern methods of Micro-Computer Tomography, Cone Beam Computer Tomography, Attenuated Total Reflection in conjunction with Fourier-Transform Infrared Spectroscopy and Artificial Intelligence Convolutional Neural Network algorithms, the paper presents the way of 3D dental pattern reconstruction and human remains identification. Research studies morphology of teeth, bone, and dental materials (Amalgam, Composite, Glass-ionomer cement) under different periods of exposure to 75% sulfuric acid; (3) Results reveal significant volume loss in bone, enamel, dentine, and as well glass-ionomer cement. Results also reveal significant resistance of composite and amalgam dental materials to sulfuric acid impact, thus serving as strong parts in the dental pattern mosaic. Paper also introduces probably first successful artificial intelligence application in automated forensic CBCT segmentation.; (4) Interdisciplinary cooperation utilizing mentioned technologies can solve problem of human remains identification with 3D reconstruction of dental patterns and their 2D projections over existing ante-mortem records.

Developmental Medicine & Child Neurology, 2005

This study investigated the effect of functional electrical stimulation (FES), applied during wal... more This study investigated the effect of functional electrical stimulation (FES), applied during walking, on the gait of children with spastic cerebral palsy (CP). Eight children (five males, three females; mean age 13y 2mo, SD 2y 2m; range 8y 11mo to 17y 6mo) diagnosed with diplegic (n=6) or hemiplegic (n=2) spastic CP completed the study. All participants were ambulant. Core FES strategies based on common CP gait deviations were developed and tailored for each child. FES strategies for each child were evaluated in two separate test sessions. Effects of FES on gait were monitored with three-dimensional motion analysis. Within each test session each child&amp;amp;amp;amp;amp;#39;s gait was assessed when walking without FES (phase A) and with FES (phase B). An A-B-A-B test sequence was employed allowing the effects of the withdrawal and reinstatement of FES to be assessed. All children performed 10 consecutive walks in each phase. Replication of this sequence on a separate day allowed the repeatability of the intervention to be evaluated. Outcome measures, including summary variables of kinematic data, temporal-spatial variables, and mode of initial contact, were predefined for each child and targets for clinical significance were set for these outcome measures. Comparisons were performed between these targets and the actual outcomes. Consistent clinically significant improvements were recorded for three children: one child showed some improvement that was statistically significant but not clinically significant. Results for one child were mixed. There was no change in the remaining three children. Gait analysis proved to be a useful tool in both developing and determining the effectiveness of FES strategies.

This work is concerned with retardation of the degradation of historical documents written in iro... more This work is concerned with retardation of the degradation of historical documents written in iron-gall ink. The main objective was to examine the effect of MMMC (methoxy magnesium methyl carbonate) neutralization agent on the stability of the paper substrate during accelerated ageing. Changes were monitored in the mechanical, chemical and optical properties of the paper caused by accelerated ageing by dry hot air (at 105 o C) and wet hot air (at 80 o C and 50% RH). Whatman paper substrate was modified with gelatine combined with aluminium sulphate. The effect of the deacidification agent used, MMMC, and of the antioxidant BHT on the inked paper substrate was determined on the basis of the results of the individual measurements.

Journal of Photochemistry and Photobiology A: Chemistry, 2000

Journal of Molecular Catalysis A: Chemical, 2000

Journal of Cultural Heritage, 2014

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2000

The rheological behaviour of three black offset inks was tested using viscometer with the cone an... more The rheological behaviour of three black offset inks was tested using viscometer with the cone and plate geometry. The shear stress versus shear rate measurements confirmed that the investigated offset inks represent similar viscoelastic, pseudoplastic fluids, forming thixotropic structure. Mileage and ink transfer curves were measured onto the paper materials with different properties. The analysis of experimental results using Tollenaar-Ernst and modified Walker-Fetsko equations established the substantial role of the paper characteristics such as smoothness, brightness and penetration in the process of ink film formation on paper substrates during printing.