Purpose
This study aims to evaluate the efficiency of using some polymers at different concentrations in the consolidation of vegetable-tanned leather artifacts.
Design/methodology/approach
New ...vegetable-tanned leather samples were prepared. The consolidants used were polyacrylamide (PAM) and polymethyl methacrylate/hydroxyethyl methacrylate (MMA-HEMA). Accelerated heat aging was applied to the untreated and treated samples. Analytical techniques used were Fourier transform infrared spectroscopy (FTIR), digital microscope, scanning electron microscope (SEM), change of color and mechanical properties.
Findings
The characteristic FTIR bands showed the effect of accelerated heat aging on the molecular structure of the studied samples, but treated and aged treated samples used were better than aged untreated samples. Microscopic investigations (digital and SEM), and mechanical properties proved that 2% was the best concentration for polymers used. The change in the total color difference of the treated and aged treated samples was limited.
Originality/value
This study presents the important results obtained from PAM and poly(MMA-HEMA) used for the consolidation of vegetable-tanned leather artifacts. The best results of the studied polymers can be applied directly to protect historical vegetable-tanned leathers.
The aim of this work was to study the influence of microwave power variation during microwave-vacuum drying on both drying time and dried material quality. Red beetroot and carrot were chosen as the ...material. The quality of the dried material was described by its color change and β-carotene loss (for carrot) due to drying.
The first series of experiments consisted of drying under constant microwave power. Only the lowest microwave power gave an undamaged product. During the second series of experiments, the microwave power was changed in time intervals. However, the use of interval conditions either had a small influence on the process time or did not provide satisfactory quality of the dried samples. During the third series of experiments, initial drying was performed with higher microwave power and then the process was continued with the lowest applied power. This method shortened the process time and gave the best quality of material.
목재의 기상열화에 관한 최근의 연구 동향 김영숙; Yeong-suk Kim
목재공학,
09/2017, Volume:
45, Issue:
5
Journal Article
Peer reviewed
Open access
본 총설에서는 목재의 기상열화 특성(색상, 목재표면의 미세구조 및 화학적 변화)과 국제적으로 다양하게 이용되는 내후성시험방법에 관한 국제적 연구동향에 대하여 보고한다.
This was reviewed on the characteristics (changes of color, microscopic structures, and chemical ...degradations) that appears on wood surface, when wood is exposed to outdoors and weathering testing methods applicable for assessment of wood weatherability in outside environment through literature reviews.
This paper reported that green pigmented deciduous teeth caused by hyperbilirubinemia could undergo light yellowish discoloration after a long period of time, and the bilirubin even in such yellowish ...teeth could be demonstrated with the light absorption analysis. A one-year-old male with green pigmented lower deciduous central incisors was referred to Chiba Children's Hospital. At the first examination, a green and yellowish area was seen in the cervical 4/5part of the crown. Shortly after birth, extensive cephalohematoma as well as disseminated intravascular coagulation occurred followed by hyperbilirubinemia,20-59.6 mg/dl on the plasma bilirubin level. Based on oral findings and his history, clinical diagnosis of bilirubin-pigmented teeth caused by hyperbilirubinemia was made. Because of no visible symptoms other than the pigmentation, the teeth were clinically followed up without any treatment. Until 3 years and 5 months of age, the green pigmentation had gradually discolored to light brown and consequently to light yellow by the age of 5years. The light yellowish deciduous teeth which shed naturally were examined and the following results were obtained. 1) With the ground section of the teeth, the pigmented band probably caused by bilirubin deposit was seen in the dentine using light microscopy. 2) Fluorescence was observed in the pigmented band by means of irradiation of 546 nm wave length light. 3) With spectrophotometric analysis (after SHIBATA, T. et al.1996), chemically extracted samples from pigmented teeth showed maximum absorption spectra at 450 nm wave length light, and after diazo reaction of the sample, they shifted from 450 to 540 nm. The absorption spectrum of the pigmented tooth samples closely paralleled that of normal ones to which bilirubin standard was added, with the former more enhanced than the latter. Based on these findings, the presence of bilirubin was demonstrated even in light yellowish pigmented teeth. Pigmentation of teeth induced by hyperbilirubinemia was also found to pass over into various color stages, such as from green to light brown or light yellow.
•Red cabbage’s anthocyanins are very stable in 48% ethanol at pH = 6.31, during 20 weeks.•From 19 compounds, tartaric and citric acid influence the most stability and colour.•Mainly, overall ...colourimetric changes are due to: acids, calcium, magnesium, natrium.•Smaller overall colour difference produce: honey, glycine, xylitol, lactose, maltose.
Red cabbage waste is a valuable source of anthocyanins which may be used as natural food dye. Excepting the colouring agents, food/beverage contains compounds from the matrix or other additives/ingredients. Present study reveals the influences of nineteen food additives/ingredients on the stability, colour parameters and radical scavenging activity during 20 weeks of storage of red cabbage waste hydroethanolic extract (initial pH = 6.31) under aerobic atmosphere, in the dark, at 4 °C. At studied concentration (0.2%), most important changes were produced by tartaric and citric acids: decrease of monomeric anthocyanins content, lightness, radical scavenging activity, and increase of polymeric colour, browning and degradation indices, chroma and red colour parameter, absolute value of blue colour parameter and hue angle, inducing very important overall colourimetric differences. Similar influences, but much attenuated, proved ascorbic and benzoic acids. During storage, the untreated extracts revealed a very high stability, and also mostly of treated extracts (especially with sugars).
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