Study of Ink Jet Print Resistance Using Various Colour Difference Formulas

Three frequently used formulas and their power function modifications were used to calculate the colour differences after the exposure to light and to study the stability of ink jet prints by spectrophotometric measurements. The prints were exposed to the simulated daylight of different spectral composition at constant conditions of temperature and relative humidity. According to the results, the black prints were the least affected and the magenta prints exhibited the biggest colour differences. The most resistant have proven to be the prints on archival paper which contained no optical brightening agents. The presence of shortwave radiation between 320 and 300 nm additionally diminished the resistance of prints. The same conclusions were obtained regardless of the colour difference formula applied, with one exception. Generally, the CIEDE2000 formula performed the best, especially when comparing samples with a smaller colour difference

Analysis of Factors Influencing Photodegradation of Ink Jet Prints

Fotodegradacija odtisa, izdelanega s kapljičnim tiskalnikom, je večplasten proces. Pri tem sodelujejo številni dejavniki: črnilo kot kompleksna mešanica kolorantov in različnih spremljevalnih snovi, papir, ki poleg različnih vlaken vsebuje tudi druge komponente, kot so na primer optična belilna sredstva, ter zunanji dejavniki, kot so temperatura, vlaga ter seveda jakost in spektralna sestava sevanja svetlobnega vira. Zato je bil namen doktorske disertacije poglobljena analiza kompleksnega procesa degradacije odtisov, izdelanih s kapljičnim tiskalnikom. V raziskavo so bili vključeni izbrani vrsti papirjev ter tiskalnika, ki uporabljata črnila na osnovi barvil. V začetni fazi so bile izvedene meritve osnovnih, kemijskih in optičnih lastnosti papirja. S pomočjo TLC, GC/MS in FTIR sta bili izvedeni podrobna analiza črnil in identifikacija komponent, ki so vključene v proces degradacije v raztopini oz. na odtisu. V nadaljevanju je bil analiziran vpliv elektromagnetnega sevanja oz. svetlobe na obstojnost raztopin črnila v inertni atmosferi in v atmosferi kisika. Proučili smo vpliv svetlobe bližnjega in kratkovalovnega UV-sevanja na odtis ter na posamezne komponente odtisa. S pomočjo barvno metričnih parametrov smo spremljali dinamiko degradacije papirja, črnila in odtisov. Rezultati so pokazali, da na spremembe lastnosti papirja vpliva predvsem kratkovalovalovno UV-sevanje. Analiza črnil je pokazala, da vsebujejo več (2–4) ter precejšnje število spremljevalnih snovi. Fotodegradacija črnil v vodni raztopini je najhitreje potekla v prisotnosti svetlobe z večjim deležem UV-sevanja, prisotnost kisika pa je hitrost degradacije črnila v raztopini še povečala. Degradacija odtisov je v večini primerov potekla hitreje pod vplivom svetlobe z večjim deležem UV-sevanja. Izkazalo se je, da je vpliv spektralne sestave svetlobe odvisen od vrste črnila in papirja, predvsem od prisotnosti optičnih belilnih sredstev v papirju. Odtisi na papirju, ki vsebuje optična belilna sredstva, so manj obstojni. Uporabljene metode proučevanja so omogočile natančno analizo degradacije posameznih komponent odtisa. Kljub temu pa je pri tolmačenju treba upoštevati, da gre pri degradaciji odtisov za medsebojni vpliv številnih notranjih in tudi zunanjih dejavnikov. Zato se je uporaba barvne metrike izkazala kot učinkovita metoda, s katero lahko spremljamo in natančno opišemo proces fotodegradacije na podlagi spremembe optičnih lastnosti odtisov. Rezultati so omogočili primerjavo hitrosti degradacije posameznih sistemov pod različnimi pogoji ter opis nastalih sprememb na odtisih, papirjih in črnilu.The photodegradation of inkjet prints is a multi-layer process. It includes several factors, such as ink as a complex mixture of colorants and various accompanying substances, paper, which in addition to various fibres also contains other components (e.g. optical bleaching agents), and external factors (e.g. temperature, humidity, and the strength and spectral composition of the radiation from a light source). The aim of the doctoral dissertation was a systematic analysis of the complex process of degradation of prints made with an inkjet printer. Selected types of paper and printers with dye-based inks were included in the research. In the initial phase, the analysis of basic chemical and optical paper properties was performed. The TLC, GC/MS, FTIR methods enabled a systematic analysis of the printing ink and identification of components involved in the process of degradation in the solution and on the print. The influence of medium-wave UV radiation on the stability of printing ink solutions in an inert atmosphere and an atmosphere of oxygen was analysed. Moreover, the influence of light, medium-wave and short-wave UV radiation on inkjet prints, and individual components were studied. To monitor the dynamics of the degradation of paper, ink and prints, colorimetric parameters were used. The results showed that the changes in paper properties were mainly caused by short-wave UV radiation. The analysis of ink revealed that they contained 2–4 colourants and a considerable number of accompanying substances. The photodegradation of ink in an aqueous solution occurred most rapidly in the presence of light with higher short-wave UV radiation. Furthermore, the presence of oxygen increased the rate of ink degradation in the solution. In most cases, the degradation of prints was faster under the influence of light with higher short-wave UV radiation. As it turned out, the influence of the spectral composition of light depends on the type of ink as well as on paper, especially on the presence of optical brightening agents in it. Consequently, the prints on paper containing optical brightening agents had inferior fastness. The analytic methods used in this study enabled a thorough analysis of the degradation of individual components of prints. However, for the interpretation of the results, it was necessary to take into account that the degradation of prints represents an interaction of many internal as well as external factors. Therefore, the use of colourimetry proved to be an effective method to monitor the photodegradation process and accurately describe it with regard to the changes in the optical properties of prints. The results enabled a comparison of the rate of degradation of individual systems under different conditions, leading to the description of changes on prints, paper and ink

Impact of protective glass on photodegradation of ink-jet printed documents

Ink-jet printing has recently been increasingly used for professional and domestic purposes. However, the degradation of ink-jet prints under the influence of external factors, predominantly light, can cause unexpected problems and lead to the limited life span of a product. It is therefore essential to have in-depth knowledge about the materials, i.e. paper and ink, used for ink-jet printing and to consider their lightfastness to assure the resistance of a print as a whole. The aim of the present research was to study the lightfastness of ink-jet prints protected with glass. Using a printer with dye-based inks, samples of cyan, magenta, yellow and black were printed on different paper substrates. Prints and substrates alone were exposed to the radiation of xenon light for a limited time to simulate the action of average daylight. Some of the samples were exposed to radiation without protection, while others were covered with ordinary window glass or glass which ensured UV protection. Afterwards, the changes on samples were evaluated spectrophotometrically and colour differences were calculated using the CIEDE2000 equation. The results showed that glass effectively reduces the photodegradation of ink-jet prints. Protection with UV glass proved to be more effective than with ordinary glass. The substrate selection was also significant in achieving print lightfastness, as much smaller colour differences were observed on the prints made on photo paper than on those printed on plain office paper

Fastness of dye-based ink-jet printing inks in aqueous solution in the presence and absence of oxygen

Photodegradation of the ink-jet prints is a complex process in which many external and internal factors are involved. Nevertheless, the role of colorants and various accompanying substances in the ink is often overlooked. Our research work aimed to determine the fastness of water-based ink-jet inks in aqueous solutions. A printing ink often contains a complex mixture of colorants to achieve optimal optical properties of color and a suitable fastness of the print. Therefore, we investigated the composition and stability of cyan, magenta, yellow, and black inks under the influence of UVC light in the presence of oxygen as well as in an inert environment based on TLC chromatography and spectrophotometric analysis. The process of photodegradation was evaluated based on ink amount and half-life. According to the results, the majority of inks consist of at least two colorants that differ in color and polarity. The results have shown that the presence of oxygen negatively affects the stability of inkstherefore, the inert atmosphere prolongs the durability of ink in water solution

Energy and Nutritional Composition of School Lunches in Slovenia: The Results of a Chemical Analysis in the Framework of the National School Meals Survey

Background: Slovenia similar to some European countries has a long tradition of the organized system of school meals. The present survey aimed to compare school lunch composition in Slovene primary schools (n = 40) with the national dietary guidelines; Methods: The survey took place from January to September 2020. Sampling of a 5-day school lunch (n = 200) for adolescents aged 10 to 13 years, were performed in schools. Chemical analysis was provided by an accredited national laboratory. Results: The median energy value of school lunches was 2059 kJ (24% of the recommended daily energy intake). The school lunches contained 24.8 g of proteins, 52.9 g of carbohydrates and 16.7 g of dietary fats. Saturated fatty acids represent 4.7 g, polyunsaturated fatty acids 4.7 g, monounsaturated fatty acids 5.8 g, and industrial trans fats 0.2 g/100 g of a meal (1.2 g/meal). Dietary fibre represented 7.8 g, free sugars for 14.7 g and salt for 3.9 g; Conclusions: The survey showed lower values for energy, carbohydrates and total fats in school lunches as recommended, and exceeded values of salt, saturated and polyunsaturated fatty acids

Dietary Intakes of Slovenian Adults and Elderly: Design and Results of the National Dietary Study SI.Menu 2017/18

Incomparable and insufficiently detailed information on dietary intakes are common challenges associated with dietary assessment methods. Being a European Union country, Slovenia is expected to conduct national food consumption studies in line with harmonised EU Menu methodology. The present study aimed to describe the methodology and protocols in the Slovenian nationally representative dietary survey SI.Menu 2017/18, and to assess population dietary habits with respect to food consumption and energy and macronutrient intakes. While the study targeted various population groups, this report is focused on adults. A representative sample of participants was randomly selected from the Central Register of Population according to sex, age classes and place of residency, following a two-stage stratified sampling procedure. Information on food consumption was collected with two non-consecutive 24-h dietary recalls using a web-based Open Platform for Clinical Nutrition (OPEN) software. Data were complemented with a food propensity questionnaire to adjust for usual intake distribution. Altogether, 364 adults (18–64 years) and 416 elderlies (65–74 years) were included in the data analyses. Study results highlighted that observed dietary patterns notably differ from food-based dietary guidelines. Typical diets are unbalanced due to high amounts of consumed meat and meat products, foods high in sugar, fat and salt, and low intake of fruits and vegetables and milk and dairy products. Consequently, the energy proportion of carbohydrates, proteins, and to some extent, free sugars and total fats, as well as intake of dietary fibre and total water deviates from the reference values. Age and sex were significantly marked by differences in dietary intakes, with particularly unfavourable trends in adults and men. Study results call for adoption of prevention and public health intervention strategies to improve dietary patterns, taking into account population group differences. In addition, all developed protocols and tools will be useful for further data collection, supporting regular dietary monitoring systems and trend analyses

Efficient paper recycling

Used paper and paper products are important raw material for paper and board industry. Paper recycling increases the material lifespan and is a key strategy that contributes to savings of primary raw material, reduction of energy and chemicals consumption, reduction of the impact on fresh water and improvement of waste management strategies. The paper recycling rate is still highly inhomogeneous among the countries of Central Europe. Since recovered paper is not only recycled in the country where it has been produced and consumed, some essential features such as eco-design and eco-collection concepts must be developed at transnational level to increase the sustainability of the paper loop. The project EcoPaperLoop addresses these needs of the regions related to paper recycling by creating a clear picture on participating region’s status, by enhancing the awareness about recyclability issues as well as by improving and sharing the collective knowledge base on available technologies and practices. To put paper recycling, in terms of yield and quality, into optimum practice all across Europe, however, appropriate paper recycling strategies are of utmost importance. In present paper some findings about paper recyclability, paper recycling strategies and legislation issues will be presented

Vitamin D Intake in Slovenian Adolescents, Adults, and the Elderly Population

Vitamin D is involved in calcium and phosphorus metabolism, and is vital for numerous bodily functions. In the absence of sufficient UV-B light-induced skin biosynthesis, dietary intake becomes the most important source of vitamin D. In the absence of biosynthesis, the recommended dietary vitamin D intake is 10–20 µg/day. Major contributors to dietary vitamin D intake are the few foods naturally containing vitamin D (i.e., fish), enriched foods, and supplements. The present study aimed to estimate the vitamin D intake in Slovenia, to identify food groups that notably contribute to vitamin D intake, and to predict the effects of hypothetical mandatory milk fortification. This study was conducted using data collected by the national cross-sectional food consumption survey (SI.Menu) in adolescents (n = 468; 10–17 years), adults (n = 364; 18–64 years), and the elderly (n = 416; 65–74 years). Data collection was carried out between March 2017 and April 2018 using the EU Menu Methodology, which included two 24-h recalls, and a food propensity questionnaire. Very low vitamin D intakes were found; many did not even meet the threshold for very low vitamin D intake (2.5 µg/day). Mean daily vitamin D intake was 2.7, 2.9, and 2.5 µg in adolescents, adults, and the elderly, respectively. Daily energy intake was found to be a significant predictor of vitamin D intake in all population groups. In adolescents and adults, sex was also found to be a significant predictor, with higher vitamin D intake in males. The study results explained the previously reported high prevalence of vitamin D deficiency in Slovenia. An efficient policy approach is required to address the risk of vitamin D deficiency, particularly in vulnerable populations

Total and Free Sugars Consumption in a Slovenian Population Representative Sample

Excessive free sugars consumption is associated with poor health outcomes. Thus, the World Health Organization (WHO) recommends limiting free sugars intake to no more than 10% of total energy intake. To evaluate current intakes of dietary sugars and monitor the adherence to the guidelines, the objective of this study was to comprehensively assess total and free sugars consumption of different age groups within the Slovenian population. The Slovenian national food consumption survey SI.Menu 2017/18 was conducted on representative samples of adolescents (10–17 years), adults (18–64 years), and the elderly (65–74 years) using two non-consecutive 24-h dietary recalls. The analyses were carried out on a sample of 1248 study participants. Free sugars content in food was estimated based on previously established databases. The population weighted median free sugars intake accounted for 10.1% of total energy intake (TEI) among adolescents, 6.4% among adults, and 6.5% in the elderly population. Both total and free sugars consumption in the percentage of TEI were higher among women than men, in participants with lower education, and those with higher family net income. The main sources of free sugars in adolescents were beverages, cakes, muffins, pastry, and dairy products; for adults and the elderly, the key sources of free sugars were beverages, cakes, muffins, pastry, and sugars, honey, and related products. A total of 56% of adolescents, 84% of adults, and 81% of the elderly population adhered to the WHO free sugars guidelines. Additional measures will be required to further decrease free sugars consumption among the teenage population, in which dietary patterns are still of greatest concern

Laying hens can convert high doses of folic acid added to the feed into natural folates in eggs providing a novel source of food folate

There are few good sources of natural food folates apart from green leafy vegetables and these may have a limited potential to increase folate status because of substantial losses that can occur during cooking. Fortified foods can overcome this but are controversial because of safety concerns regarding chronic exposure to high-dose folic acid (FA; the synthetic form). The aim of the present study was to develop eggs with an enriched natural folate content and minimal unmetabolised FA. Forty-eight, 30-week-old laying hens were randomised to receive the basal feed (formulated to provide 1 mg folate/kg feed) to which had been added one of the following FA levels (0, 2, 4, 8, 16, 32 mg/kg feed). Total folate was measured in eggs collected throughout the 12-week study period and the FA content estimated at 12 weeks. Results showed that the maximal egg folate content was achieved by adding 16 mg FA/kg feed. At this optimal dose, the total folate content per egg was 75 microg (compared with 32 microg in a regular egg) of which FA represented at most 10%, a level which would probably be converted into natural folates by humans after ingestion. The results demonstrate that it is possible to use synthetic FA at high doses to produce novel animal foods enriched with natural folates in a cost-efficient process. Such foods may be particularly relevant to European populations without access to FA fortification and therefore dependent on natural food folate sources for the primary prevention of folate-related disease