Varnish Layers Research Articles

Thermal deformations of a glass spherical satellite

The effect of the kind of the reflecting coating of a glass spherical satellite on thermal deformations caused by the solar irradiation is considered. Two types of coating deposited on one of the hemispheres are considered: aluminum with a protective layer of bakelite varnish and interference dielectric coating for two orientations of the satellite orbit. Structures of a multilayer dielectric coating and technologies of its deposition are described.

Fungi as deterioration agents of historic glass plate negatives of Brandys family collection

Microbiological deterioration was observed on a historic collection of retouched glass plate negatives. The collection came from a burnt manor house that belonged to the Brandys family before World War IInd. The photographs were taken at the end of 19th century. The collection consists of 35 glass plate negatives, 4 of which were examined for possible presence of microorganisms. The current state of the negatives indicated that the collection may have been flooded. Initially, the viability of the microorganisms on the plates was examined using luminescence adenosine phosphate assay. The fungi were isolated and identified with molecular biology methods as Trichoderma longibrachiatum, Hypocrea lixii, Aspergillus versicolor, Penicillium sp. As the historic negatives were covered with a protective varnish layer, the impact of the isolated fungi on test negative plates covered with dammar and sandarac varnishes, and on a gelatine image layer were examined. The most effective in degradation of gelatine emulsion was T. longibrachiatum. All of the investigated microorganisms quickly decomposed silver image in gelatine layer not covered with varnish in opposite to slower decomposition of silver image in gelatine layer covered with sandarac and dammar varnishes. UV-induced luminescence observation confirmed that the microorganisms quickly decomposed gelatin layer not covered with varnish. The cracking of varnish was the result of fungal activity within gelatin, however, some fungi also attacked the varnish itself.

The effects of surface roughness on varnish adhesion strength of wood materials

In this study, the effects of surface roughness of wood material on the adhesion strength of varnish layers have been tested. For this purpose, test samples of beech (Fagus orientalis L.), Scots pine (Pinus sylvestris L.), and cherry (Prunus cerasus) wood species were prepared and sanded with 80, 120, and 180 grit abrasives. The surface roughness values of specimens were determined using a stylus-type profilometer TIME TR 200 according to the ISO 4287 standards. Then, water-based, polyurethane, and acrylic varnish were applied to the surfaces of the samples in accordance with ASTM-D 3023. Layer adhesion strength was determined to the TS EN ISO 4624 standards. As a result, the highest adhesion strength value (2.52 N/mm2) was found in cherry, while the Scots pine had the lowest value (2.32 N/mm2). For the varnish types, polyurethane varnish types gave the highest value (3.15 N/mm2), while the lowest value was obtained from the water-based varnish. Looking at interactions between adhesion strength and surface roughness, the water-based varnish had the strongest correlation with adhesion strength (69%) and acrylic varnish also had a similar result (67%), while polyurethane varnish had the weakest result (33%) in this interaction.

A review of surface effects in Kapitza's experiments on heat transfer between solids and helium II (Review Article)

In a recent paper, it is shown that the thermal boundary Kapitza resistance between a solid and superfluid helium is explained by resonant scattering of phonons from surface roughness heights, as described in the Adamenko and Fuks (AF) model. We reexamine the original experiments of thermal transfer between a solid (platinum and copper) and superfluid helium conducted by Kapitza in 1940. In particular, we analyze his experimental results for the different surface treatments of the solid in light of the AF model. Time scales for diffuse scattering of phonons at the interface are estimated. Also the role of a layer of varnish on a copper surface is reinterpreted.

Prevention of Enamel Adjacent to Bracket Demineralization Following Carbon Dioxide Laser Radiation and Titanium Tetra Fluoride Solution Treatment: An In Vitro Study.

Introduction: The aim of this study was to assess the caries-preventive potential of carbon dioxide (CO2) laser application in conjunction with the use of titanium tetra fluoride solution on the enamel adjacent to bracket. Methods: Seventy-five freshly extracted bovine incisors were used. In order to attach the brackets, the area of examination was covered with adhesive tape to limit acid etching of the entire enamel surface. Metal orthodontic brackets for upper central were bonded to all the teeth following the manufacturer's instruction. Then all the teeth were painted with 2 layers of acid-resistant nail varnish on all surfaces except the boxes area cervical to the brackets. The teeth were then randomly divided into five groups (n = 15): control group (C); laser group (L); titanium group (T); laser-titanium group (LT) and titanium-laser group (TL). The laser-titanium group was first irradiated with CO2 laser (same as the L group) then TiF4 solution was applied on the enamel (same as the T group). Samples in the TL group were first treated with TiF4 solution (same as the T group) and then irradiated with CO2 laser on the surface (same as the L group). Then, the teeth were immersed in pH-cycling solutions. After that, the amount of calcium released into the two solutions (de- and re-mineralization) was measured with an atomic absorption spectroscopy. The data were analyzed by one-way Analysis of var-iance (ANOVA) and Tukey test. Results: Calcium loss in LT, TL and T groups were significantly lower than those in the L and C groups (P < 0.05). Conclusion: The application of Titanium tetra fluoride 4% solution on enamel can inhibit as much as 87% of subsequent caries like lesion progression.

A national survey of tracheal tube introducers and associated complications

Tracheal tube introducers (bougies) are frequently used by anaesthetists in the UK for the management of difficult tracheal intubation. The re-usable gum elastic bougie (GEB) is regarded as the gold standard. However, there are concerns about the risks of cross-infection, detachment of the tip or fracture of the outer varnish layer with re-usable GEBs. Despite evidence showing that the GEB has a higher success rate for tracheal placement 1 and that single-use tracheal tube introducers have potential to produce airway trauma, oesophageal perforation and pneumothorax 2, 3, there has been a move towards single-use airway devices. Concerns have been raised about the lack of evidence for clinical efficacy or safety 4. With approval from the Difficult Airway Society (DAS) Survey Committee, an email with a link to an online survey was sent to all UK DAS members in March 2013, asking about the type of introducers used and whether any complications had been associated with their use. Results of the 485 DAS members who replied (36% response rate) are summarised in Table 1. Our data shows that the GEB is associated with the lowest complication rate and its use is preferred by the majority of DAS members. However, at approximately £30 (€38, $43), it is more than twice as expensive as single-use devices 5, and fewer hospitals are seemingly prepared to permit the routine use of the GEB compared to 10 years ago 6. We propose that newer single-use tracheal tube introducers require urgent further evaluation 7 before they are considered suitable replacements for the re-usable gum elastic bougie.

Analytical imaging studies of the migration of degraded orpiment, realgar, and emerald green pigments in historic paintings and related conservation issues

Yellow orpiment (As2S3) and red–orange realgar (As4S4) photo-degrade and the nineteenth-century pigment emerald green (Cu(C2H3O2)2·3Cu(AsO2)2) degrades into arsenic oxides. Because of their solubility in water, arsenic oxides readily migrate and are found throughout the multi-layered paint system. The widespread arsenic migration has consequences for conservation, and this paper provides better insight into the extent of the problem. Five paint samples containing orpiment, realgar or emerald green pigments deriving from paintings by De Heem (17th C), Van Gogh (19th C), Rousseau (19th C), an unknown 17th C northern European artist and an Austrian painted cupboard (19th C) were investigated using SEM/EDX, imaging ATR-FTIR and arsenic (As) K–edge μ-XANES to obtain the spatial distribution and chemical speciation of arsenic in the paint system. In all of the samples investigated arsenic had migrated throughout the multi-layered paint structure of the art object, from support to varnish. Furthermore, As5+-species were found throughout the entire paint sample. We hypothesize that arsenic trioxide is first formed, dissolves in water, further oxidizes to arsenic pentaoxide, and then reacts with lead, calcium and other ions and is deposited in the paint system as insoluble arsenates. Since the degradation of arsenic pigments such as orpiment, realgar and emerald green occurs through a highly mobile intermediate stage, it not only affects the regions rich in arsenic pigments, but also the entire object, including substrate and top varnish layers. Because of this widespread potential for damage, preventing degradation of arsenic pigments should be prioritized and conservators should minimize exposure of objects containing arsenic pigments to strong light, large fluctuations in relative humidity and water-based cleaning agents.

Comparison of Bond Strength and Apical Seal Obtained in Root Canals Prepared with a New Rotary System Endo Eze System and Obturated with Two Different Techniques

The aim of the present study was to compare bond strength and apical seal obtained in root canals prepared with a new rotary system (Endo-Eze) and obturated with two different techniques (AH Plus sealer/ gutta-percha points and EndoREZ sealer/ EndoREZ points). Sixty freshly extracted mandibular first molars were used in this study. The distal root of each collected tooth was removed by tapered diamond stone mounted in high-speed handpiece. Mesio-buccal canals of teeth were cleaned and shaped by Endo-Eze system, then they were classified into two main groups of 30 each accordingto obturation materials used, Group (1): canals were obturated with lateral condensation using AH-Plus sealer and gutta-percha and Group (2): canals were obturated with lateral condensation using Endo-REZ sealer and Endo-REZ points. Within each group, samples were divided into 2 subgroups of 15 each according to assessment method, subgroup (A): 15 teeth were used for assessment of microleakage and subgroup (B): 15 teeth were used for assessment of push-out bond strength. Subgroup (C): 15 teeth were used for assessment of microleakage and subgroup (D): 15 teeth were used for assessment of push-out bond strength. Then subgroups A & C were further divided into 3 divisions according to storage time (immediately, one month and three months) after setting of the sealer. Assessment of microleakage was done by dye penetration test where 2 layers of nail varnish were applied to all the root surfaces except the apical 2 mm, thenthe apices of the teeth were immersed in 2 % methylene blue dye solution for 2 days. Examination for linear dye penetration was done using stereomicroscope. Assessment of bond strength was done by push-out test where compressive load was applied apicocoronally in order to push the filling material toward the larger diameter. The resultsregarding the microleakage showed that the immediate observation period in (AH Plus / gutta-percha) recorded the highest statistically significant leakage mean value while the lowest mean value was recorded in the 3 months observation period of Endo-Rez / Endo-Rez points. Regarding the push out bond strength, it was found that AH Plus /

A Comparative Analysis of the Microfabrics of Surface Horizons and Desert Varnish in Extremely Arid Soils of the Mojave (USA) and Trans-Altai Gobi (Mongolia) Deserts

The mineralogical composition of coarse fraction and characteristic features of the micro- and submicrofabrics and chemical composition of desert varnish on gravels of desert pavements and the underlying vesicular crust soil horizons were studied in the extremely arid soils of the Mojave (USA) and Trans-Altai Gobi (Mongolia) deserts. A set of common diagnostic features of elementary pedogenetic processes was identified in the automorphic desert soils developed on ancient (70–90 ka) piedmont plains composed of alluvial deposits with the high content of red-earth clay. The results of this study attest to the long and complicated history of the extremely arid soils with alternation of the humid and arid phases of pedogenesis reflected in a specific combination of textural (clay-illuvial) and carbonate pedofeatures and in the distribution patterns of iron, manganese, titanium, and barium in different layers of the desert varnish. The chemical composition of the latter did not depend on the mineralogical composition of the underlying substrates and was formed with active participation of soil microorganisms. This allowed us to conclude about the polygenetic (accretionary–microbiological) nature of desert varnish.

DYE EXTRACTION METHOD EVALUATION OF THE SEALING ABILITY OF THREE TYPES OF ENDODONTIC SEALERS

This study aimed to: evaluate the sealing ability of AH Plus sealer, IRoot SP sealer, and Epiphany-Resilon root canal filling system by Dye extraction method. Methods: 45 freshly extracted single rooted human teeth were instrumented with Revo-S; the sequence used was SC1, SC2, SU, AS30, AS35, and AS40 taper 0.06. The prepared specimens were then divided randomly into Negative controls (n = 9) and Positive controls (n = 9); the negative controls were completely covered with three layers of varnish, and the positive controls were enlarged, but not root filled. The remaining 27 teeth were then randomly divided into three groups of 9 teeth each according to the type of sealer used, as the following: Group 1 (AH Plus sealer), Group 2 (IRoot SP sealer), and Group 3 (Epiphany-Resilon root canal filling system). Apical leakage evaluation was done by dye extraction methods. Data were statistically analyzed. Results: The positive control showed total dye absorbance of 5000, while negative control samples had a low absorbance of 75. The mean absorbance values were 370, 315, and 400 for Group 1 (AH Plus), Group 2 (IRoot SP), and Group3 (Epiphany-Resilon root canal filling system) respectively. Conclusion: The three tested sealers had the similar capability in apical sealing.

A Comparative Evaluation of Sealing Ability of New MTA Based Sealers with Conventional Resin Based Sealer: An In-vitro Study.

Root canal obturation is the most important step in the root canal treatment that aims to obtain a complete hermetic seal and to prevent the re-growth of microorganisms in the root canal system. To accomplish this, many endodontic obturation materials and sealers are being used. To evaluate and compare the apical microleakage of a resin based sealer; Adseal with Mineral Trioxide Aggregate (MTA) based sealers; Pro root MTA and MTA Fillapex. Total 75 extracted human single rooted teeth were taken and decoronated at cemento-enamel junction. The access cavities and biomechanical preparation were performed using endodontic rotary system. The teeth were randomly divided into five groups with n=15; Group I - Gutta-percha and Adseal sealer; Group II - Gutta-percha and MTA Fillapex; Group III- Gutta-percha and Pro root MTA; Group IV- Gutta-percha without sealer (positive control group); Group V- Root canal remained empty (negative control). All the specimens were stored at 37(0)C with 100% humidity for one week. All root surfaces except the apical 2mm were covered with two layers of nail varnish and then immersed in an aqueous solution of 2% methylene blue dye for 72 hours. Roots were longitudinally split using a diamond disk. Linear apical dye penetration was measured under Stereomicroscope at 40X magnification. The data obtained was subjected to statistical analysis using paried t-test, ANOVA for interclass comparison, with SPSS statistical software (version 20.0). The intraobserver reliability was found to be insignificant in each of the triplicate study of all the three study samples. MTA Fillapex group showed maxmium apical microleakage followed by Pro root MTA and Adseal sealer. The results concluded that Adseal sealer showed minimal dye penetration followed by Pro root MTA and MTA Fillapex. Thus, concluding that Adseal sealer is better in apical sealing than Pro root MTA and MTA Fillapex.

Yağlı Isıl İşlem Görmüş Sarıçam Odunlarında Koruyucu Katmanın Yapışma ve Sertlik Özellikleri

Wood is a preferred important material due to having many advantages for many uses. However, wood is degraded by time under the effects of biotic and abiotic factors. Therefore, wood should be protected from fungi, insects and other climate factors. Among these, heat treatment methods increase the durability of wood properties. Especially, oil heat treatment improves the dimensional stability and color stability in a positive direction. Thus, wood can be used for garden furniture or siding. In this study, water based varnish and paint were applied on oil heat treated scots pine (Pinus sylvestris L.) wood. Effects of oil heat treatment on adhesion strength and hardness of varnish and paint films were determined. Results showed that hardness of varnish layers (38) on oil heat treated scots pine wood is higher than paint layers (25.6)

Potential of Soundproof Wallpaper Based on Indigenous Materials

Noise exposure can occur at any time and interfere with a person's psychological and biological condition. Alternative materials from banana midrib and soybean dregs can be used as sound absorbers based on their characteristics and abundance. This research aims to analyze the optimal composition for sound-absorbing composite materials from banana midrib and soybean dregs and the effect of adding a layer of varnish to its absorption capacity. The method includes the manufacture of the sample, the impedance tube, the box acoustic approach, and the CCD test. The drying process of banana midrib is divided into two types, namely those that are dried in the sun and oven with the banana midrib having gone through a 5% NaOH immersion process before drying. The application of varnish on the sample used the cold spray technique so the layer is not thick and provides durability and resistance to the sample. The impedance tube was carried out to analyze the value of the sound absorption coefficient of the sample at several frequencies which were then averaged. After being tested with the box acoustic approach, the sample has the ability to reduce sound when applied to the walls of the room with an average percentage decrease of 10.84%. Through the CCD test, it is known that the size and number of pores distribution affects the sound absorption capacity. Banana midrib and soybean dregs can be used as an alternative to sound absorbers with the average value meeting the ISO 11654 standard, which is 0.15.

Application of non-invasive optical monitoring methodologies to follow and record painting cleaning processes

The cleaning of painted artworks, i.e. the critical operation whereby materials are selectively removed from a painted surface by partial thinning or complete elimination of varnish, is one of the most debated conservation operations, being an irreversible process, which may result in chromatic and morphological variations in the painted surface. Due to ageing, the upper layer is subject to darkening and yellowing because of blanching and fading from ultraviolet exposure, dust deposition, and overpainted layers due, for instance, to restoration interventions. This degradation can either alter the original appearance of painting polychromy or cause mechanical failure of the finishes. To address these adverse conditions, a process of examination and analysis is critical to the definition and interpretation of the varnish layer. When investigating the ageing process of old paintings, it is of great importance to obtain insight into the painting technique as practiced in the past, and the first step in gaining this knowledge is, to a large extent, based on the study of the varnish film. An effective control of the process and objective evaluation of its outcome requires therefore instrumental/analytical support. The present study illustrates the successful application of non-invasive optical techniques—such as colorimetry, multispectral reflectography, laser scanning micro-profilometry, and optical coherence tomography—to the monitoring of an Italian fourteenth-century painting cleaning process. Results presented here confirm that optical techniques play a pivotal role in artwork diagnostics, especially with regard to conservation operations, while also indicating their validity when applied to the monitoring of the cleaning process.

Minimal invasive control of paintings cleaning by LIBS

In cultural heritage restoration and conservation, it has been proved that LIBS is an appropriate technique for pigments identification, analysis of multilayered paintings, and quantitative analysis of ancient materials. Generally, experiments involving the use of laser for paint cleaning and LIBS in order to identify the composition of the removed material are made. Here, we report LIBS studies on mastic and dammar varnishes removal using visible (532nm) and UV (266nm) laser pulses (5ns) with fluences in the range 0.6–4.4J/cm2. The studied varnish layers were on-purpose painted on glass supports or were part of several mock-up samples having dammar or mastic as final layer – gold foil, yellow ochre or cobalt blue egg tempera as painting layer – chalk or acrylic ground as link to an wooden support. LIBS was used to monitor the laser induced stepwise selective removal of the layers and to analyze their composition.

Blanching of paint and varnish layers in easel paintings: contribution to the understanding of the alteration

The blanching of easel paintings can affect the varnish layer and also the paint layer with a blurring effect. The understanding of the physicochemical and optical phenomena involved in the whitening process remains an important challenge for the painting conservation. A set of ca. 50 microsamples from French, Flemish, and Italian blanched oil paintings, from sixteenth to nineteenth century, have been collected for in deep investigations. In parallel, the reproduction of the alteration was achieved by preparing some paint layers according to historical treatises and altering them in a climatic chamber in a humid environment or directly by immersing in ultrapure water. The observation of raw samples with a field-emission gun scanning electron microscope revealed for the first time that the altered layers have an unexpected highly porous structure with a pore size ranging from ca. 40 nm to 2 μm. The formation mechanism of these pores should mostly be physical as the supplementary analyses (Fourier transform infrared spectroscopy, gas chromatography–mass spectrometry) do not reveal any noticeable molecular modification. Considering the tiny size of the pores, the alteration can be explained by the Rayleigh or Mie light scattering.

Analytical study of Saint Gregory Nazianzen Icon, Old Cairo, Egypt

The study aims to evaluate the state of icon through characterization of the icon layers (ground, paint and varnish layers) and to provide tools for assessment the impact of aging and environmental conditions in order to produce some solutions for conservation of the icon. Analytical techniques used in this study were attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscope-energy dispersive X ray spectroscopy (FESEM-EDX) and amino acid analyzer (AAA). The results obtained revealed that gypsum and lead white were used for ground layer. The identified pigments were lamp carbon black, brown ochre, Prussian blue, yellow ochre and gold leaf. Egg yolk was the binder used with most of pigments and animal glue was used with gold color. The varnish used was shellac resin. It was concluded that stable pigments gave permanent colors and environmental conditions had an influence on promotion of oxidation process. Auto-oxidation of binder and varnish materials occurred by the action of pigment components and light result in cracking of the paint film and fading of the varnish glaze.

Evaluation of Different Dentin Bonding Agents Accompanied with Composite Coronal Barrier

Introduction: The purpose of this study was to evaluate the sealing ability of dentin bonding agents in root canals obturated with gutta-percha and MTA. Methods: Forty-five single rooted human premolar teeth were decoronated so that remaining root portions were 12 mm in length. The samples were divided randomly into three experimental (n=13) and two control groups (n=3). All teeth were instrumented up to #40 K-file using step-back technique. The roots were obturated with gutta-percha/AH26 and MTA for 5 and 3 mm, respectively. Excite, Clearfil SE Bond, and iBond were applied for experimental groups and then 2mm was filled with composite Filtek Z250. The roots in the controls were merely instrumented and obturated. Two coats of nail varnish were applied on the surface of the teeth in the experimental and positive groups, except 2 mm around the apical foramen and coronal surfaces. In the negative control, the surfaces were completely covered by two layers of nail varnish. After thermocycling, the roots mounted in plastic caps of tubes containing BHI medium and inoculated coronally with Enterococcus faecalis. The data were statistically analyzed using Fisher's exact and Kaplan-Meier survival Analysis. Results: There were no statistically significant differences between three experimental groups regarding the leakage rate (P=0.738). Conclusion: Within the limitations of this study, it was observed that the adhesive systems in alliance with gutta-percha and MTA obturation could not entirely

Obturation Techniques Allow Microbial Leakage Unless Protected.

To evaluate the quality of the apical 5-mm seal produced by different filling techniques using a bacterial leakage model. Sixty-five extracted single-rooted human teeth were decoronated, prepared, and instrumented. Roots were randomly divided into three experimental groups (15 roots each) and control groups (10 roots each). The apical 5 mm was filled with cold lateral condensation (CLC) technique, continuous wave of condensation (CWC), or injectable thermoplasticized gutta-percha (Obtura II) using AH26 Plus as a sealer. Positive controls were filled with gutta-percha without sealer, whereas negative controls were filled with a CLC technique and covered completely with two layers of nail varnish, including the orifice. A dual-chamber leakage model using Enterococcus faecalis as a microbial marker was used for leakage evaluation. Bacterial penetration was monitored over a 60-day period, and leakage was recorded when turbidity was observed in the lower chamber. All positive controls exhibited turbidity in the lower chamber within 24 hours. All negative controls demonstrated no bacterial leakage for the entire 60-day observation period. The estimated mean day for leakage was 32 for CLC, 35 for CWC, and 30 days for Obtura II. Wilcoxon test showed no statistically significant difference (p = 0.98) in the survival time between the experimental groups. The three filling techniques produced similar resistance to bacterial leakage when used to fill the apical 5-mm segment of the canal while leaving the rest of the canal unfilled.

Evaluation of Pumice, Fissure Enameloplasty, Dentin Adhesive and Air Abrasion on Sealant Microleakage

Aim: To evaluate microleakage of pit and fissure sealant after using four different pit and fissure preparation techniques. o C, for 500 cycles with dwell time of 30 seconds then stored in 0.9% normal saline. All teeth were sealed apically and coated within 1.5 mm of the sealant margin with 2 layers of nail varnish. The teeth were immersed in a 1% solution of methylene blue for 24 hours to allow dye penetration. Three buccolingual cuts parallel to the long axis of the teeth were made yielding 4 sections and 6 surfaces per tooth for analysis. The surfaces were scored 0 to 3 for extent of microleakage using a binocular microscope at 25x magnification. Results: There was no significant difference in microleakage between the four groups although the air abrasion and acid etching exhibited the least microleakage followed by enameloplasty and acid etching then the self etching adhesive system, and the highest microleakage was pumice and acid etching. Conclusions: Neither air abrasion and enameloplasty followed by acid etching nor the self etching adhesive system produced significantly less microleakage than the traditional pumice prophylaxis with acid etching technique.