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Review of methods for early forest fire detection
No full textSenzori za detekciju i praćenje požara u šumama igraju ključnu ulogu u suvremenim sustavima za rano otkrivanje i sprječavanje nastanka požara. Ovi sofisticirani uređaji osmišljeni su kako bi prepoznali različite znakove požara, poput prisutnosti dima, povišenja temperature, ili povećane koncentracije plinova, te pravovremeno upozorili nadležne službe ili korisnike, minimizirajući time rizik od ozbiljnih posljedica. Rad opisuje primjenu nekoliko vrsta senzora za detekciju požara, od kojih su najčešći termalni, optički, i ionizacijski senzori. Kombinacijom ovih tehnologija postiže se visoka razina pouzdanosti u detekciji požara u različitim okruženjima, uključujući domaćinstva, industrijske pogone i javne ustanove.
Važnost brze i točne detekcije požara ne može se prenaglasiti. Rani uvid u početnu fazu požara omogućuje bržu reakciju vatrogasaca i spašavanje života te imovine. Moderni senzori za praćenje požara često su povezani u mreže koje omogućuju centralizirano upravljanje i praćenje, što dodatno poboljšava efikasnost i brzinu reakcije. Implementacija senzora za praćenje požara može uključivati i integraciju s drugim sustavima za sigurnost, poput sustava za gašenje požara ili upravljanje ventilacijom. Ova integracija omogućuje automatizirane odgovore na požar, uključujući kontrolu prometa zraka radi sprječavanja širenja dima.
Uz napredak tehnologije, senzori za praćenje požara postaju sve sofisticiraniji, s mogućnostima kao što su analiza podataka u stvarnom vremenu, predikcija pojave požara i daljinsko upravljanje. Ovi napredni sustavi pomažu u smanjenju rizika od požara, što je ključno za zaštitu ljudi, imovine i okoliša. Senzori za praćenje požara su nezamjenjivi alati za održavanje sigurnosti u suvremenom svijetu, pružajući ranu detekciju i omogućujući brze reakcije koje spašavaju živote i imovinu.Fire detection and monitoring sensors in forests play a crucial role in modern systems for early fire detection and prevention. These sophisticated devices are designed to detect various signs of fires, such as the presence of smoke, rising temperatures, or increased gas concentrations, and to promptly alert the relevant authorities or users, thereby minimizing the risk of severe consequences. This thesis describes the application of several types of fire detection sensors, with the most common being thermal, optical, and ionization sensors.
The combination of these technologies ensures a high level of reliability in fire detection in various environments, including households, industrial facilities, and public institutions.
The importance of quick and accurate fire detection cannot be overstated. Early awareness of the initial phase of a fire allows for a faster response by firefighters, saving lives and property. Modern fire monitoring sensors are often connected in networks that enable centralized management and monitoring, further improving efficiency and response speed. The implementation of fire monitoring sensors can also include integration with other safety systems, such as fire suppression systems or ventilation control. This integration allows for automated responses to fires, including the activation of sprinkler systems or air traffic control to prevent the spread of smoke. With technological advancements, fire monitoring sensors are becoming increasingly sophisticated, with capabilities such as real-time data analysis, fire prediction, and remote control. These advanced systems help reduce fire risks, which is crucial for protecting people, property, and the environment. Fire monitoring sensors are indispensable tools for maintaining safety in the modern world, providing early detection and enabling rapid responses that save lives and property
The impact of detergents on the tissue decellularization efficacy
No full textSve veća potreba za nadomjestkom određenog tkiva ili organa, uz manjak donora, za sobom povlači novu sferu interesa kroz tkivno inženjerstvo i razvoj tkiva in vitro. Takav se poduhvat bazira na nacjepljivanju stanica na nosač izvanstanične matrice od biomaterijala izražene biokompaktibilnosti. Pri tome se stvara trodimenzionalno izgrađeno kompleksno tkivo, koje se potom transplantira. Kako bi se izvanstanična matrica izolirala, postala nosačem za stanice te zadržala svoju strukturu, potrebno je proći kroz proces decelularizacije. U tom je procesu tkivo podvrgnuto fizikalnim, kemijskim i enzimatskim postupcima. U ovome je radu provedena decelularizacija svinjske jetre putem kemijske metode, gdje su upotrebljavani detergenti: natrijev lauril sulfat (SDS), natrijev lauret sulfat (SLES), Triton-X 100 i Tween 20.
Nakon provedenih decelularizacija, postupak se nastavio kvantifikacijom bioloških komponenata kojima je utvrđena koncentracija prisutne deoksiribonukleinske kiseline (DNK), kolagena i glikozaminoglikana (GAG). Dodatno je analizirana struktura tkiva svjetlosnim mikroskopom i stereomikroskopom. Rezultati istraživanja pokazali su varijabilnu učinkovitost detergenata poput SDS-a, SLES-a, Triton-X 100 i Tween 20 u procesu decelularizacije svinjske jetre. Kvantifikacija sadržaja DNK, kolagena i glikozaminoglikana (GAG-a) u decelulariziranim uzorcima tkiva otkrila je različitu sposobnost detergenata u očuvanju ovih ključnih komponenata. Mikrografije tkiva dodatno su ilustrirale oštećenja i puknuća u strukturi izvanstanične matrice, s nekim detergentima koji su uzrokovali veća oštećenja od drugih.
Ovi rezultati naglašavaju potrebu za pažljivim odabirom detergenata i optimizacijom procesa decelularizacije kako bi se minimizirala oštećenja strukture tkiva i osigurala njihova biokompatibilnost za buduću primjenu.Increasing need for the replacement of a specific tissue or organ, with a smaller number of donors, entail a new sphere of interest through tissue engineering and tissue development in vitro. Such an undertaking is based on the grafting of a cell on an extracellular matrix carrier made of biomaterials with pronounced biocompatibility. In doing so, a three-dimensional complex tissue is created, which is then transplanted. In order for the extracellular matrix to be isolated, become a carrier for cells and retain its structure, it is necessary to go through the decellularization process. In this process, the tissue is subjected to physical, chemical and enzymatic procedures. In this work, decellularization of porcine liver was carried out by a chemical method using 1% solutions of detergents sodium lauryl sulfate (SDS), sodium laureth sulfate (SLES), Triton-X 100 and Tween 20. After the decellularization, the obtained samples were tested using quantification methods, in order to measure the presence of DNA, collagen and GAG for the detection of residual biological material. In addition to various methods of quantification, the tissue structure was analyzed using a light microscope and a stereomicroscope. The research results showed variable effectiveness of detergents such as SDS, SLES, Triton-X 100, and Tween 20 in the decellularization process of porcine liver. Quantification of DNA, collagen, and glycosaminoglycan (GAG) content in decellularized tissue samples revealed the different abilities of detergents in preserving these key components. Tissue micrographs further illustrated damages and ruptures in the extracellular matrix structure, with some detergents causing greater damage than others. These findings emphasize the need for careful selection of detergents and optimization of the decellularization process to minimize tissue structure damage and ensure their biocompatibility for future applications
Stability of cosmetic products under ultraviolet radiation
No full textOvaj završni rad bavi se istraživanjem stabilnosti kozmetičkih proizvoda pri izlaganju UV zračenju. Formulacija kozmetičkih proizvoda zahtjeva poznavanje čimbenika koji mogu imati utjecaj na stabilnost i ponašanje istih. UV (ultraljubičasto) zračenje jedan je od čimbenika koji je potrebno uzeti u obzir jer izaziva fotodegradaciju sastojaka u kozmetičkim proizvodima, što rezultira promjenom boje, mirisa, teksture, učinkovitosti i sigurnosti kozmetičkih proizvoda. Stabilnost, sigurnost i kvaliteta proizvoda imperativi su u kemijskoj industriji stoga je potrebno istražiti različite vrste UV zračenja te njihove učinke na različite skupine kozmetičkih proizvoda. SPF (Sun Protection Factor) mjera je zaštite koju određeni proizvod pruža od UV zračenja koje može izazvati opekline ili razvoj raka kože, a danas je razina svijesti o štetnosti sunčeva zračenja dobro poznata pa su takvi proizvodi sve zastupljeniji u raznim oblicima i formulacijama. Proizvodi sa SPF faktorom sadrže kombinaciju sastojaka poput UV filtera i antioksidansa koji povećavaju fotostabilnost i tako smanjuju rizik od iritacija ili alergijskih reakcija koje mogu nastati zbog fotodegradacije sastojaka. Kako bi se evaluirala fotostabilnost kozmetičkih proizvoda uslijed izlaganja UV zračenju koriste se razne tehnike kao što su HPLC (High-Performance Liquid Chromatography) i UV/VIS spektrofotometrija. Također, važan faktor za stabilnost osim formulacije je i odabir pakiranja te skladištenja proizvoda. Kontinuirano se razmatraju različite strategije kojima bi se mogla poboljšati stabilnost kozmetičkih proizvoda izloženih UV zračenju poštujući regulatorne zahtjeve i standarde.This thesis investigates the stability of cosmetic products when exposed to UV radiation.
The formulation of cosmetic products requires knowledge of factors that can affect their stability and behavior. UV (ultraviolet) radiation is one of the factors that must be considered because it causes photodegradation of ingredients in cosmetic products, resulting in changes in color, scent, texture, efficacy, and safety. Stability, safety, and quality of products are imperatives in the chemical industry; therefore, it is necessary to investigate different types of UV radiation and their effects on various groups of cosmetic products. SPF (Sun Protection Factor) is a measure of protection provided by a product against UV radiation that can cause burns or the development of skin cancer, and today the awareness of the harmful effects of sun radiation is well known, making such products increasingly prevalent in various forms and formulations. Products with an SPF factor contain a combination of ingredients such as UV filters and antioxidants that enhance photostability, thereby reducing the risk of irritation or allergic reactions that can result from the photodegradation of ingredients. Techniques such as HPLC (High-Performance Liquid Chromatography) and UV/VIS spectrophotometry are used to evaluate the photostability of cosmetic products due to UV exposure. Additionally, an important factor for stability, besides formulation, is the selection of packaging and storage of the products. Various strategies are continuously considered to improve the stability of cosmetic products exposed to UV radiation while adhering to regulatory requirements and standards
Recent advances in development of solid state electrolyte batteries for next generation electrical vehicles
No full textOvaj rad daje pregled najnovijih saznanja o baterijama s čvrstofaznim elektrolitom. Kako baterije s tekućim elektrolitom posjeduju probleme kratkog spoja i zapaljenja, razvoj se okrenuo sigurnijim baterijama s čvrstofaznim elektrolitima. U radu je opisan dosadašnji razvoj litijevih baterija koje su najzastupljenije i koje posjeduju najbolje performanse. Opisano je nekoliko vrsti litijevih baterija, te njihova najbitnija elektrokemijska svojstva i materijali od kojih su sačinjene. Navode se glavni problemi i rješenja za komercijalni razvoj tih baterija. Također se opisuju i alternativni materijali i tehnologije koje bi zamijenile litijeve baterije te njihov trenutni napredak. Na kraju su navedene poželjne karakteristike baterija za primjenu u električnim vozilima, te komercijalni proizvođači vozila i baterija na globalnoj razini.This paper provides an overview of the latest knowledge on batteries with solid-state electrolyte. As liquid electrolyte batteries have short-circuiting and ignition problems, development has turned to safer solid-state electrolyte batteries. The paper describes the current development of lithium batteries, which are the most common and have the best performance. Several types of lithium batteries are described, as well as their most important electrochemical properties and the materials they are made of. The main problems and solutions for the commercial development of these batteries are listed. Alternative materials and technologies that would replace lithium batteries and their current progress are also described. At the end, the desirable characteristics of batteries for use in electric vehicles, and commercial manufacturers of vehicles and batteries on a global scale, are listed
Electrochemical synthesis of 2-methoxy-4-(3-methyloxiran-2-yl)phenol
No full textCilj ovog rada bio je sintetizirati 2-metoksi-4-(3-metiloksiran-2-il)fenol elektrokemijskom epoksidacijom uz bromidni medijator. Eugenol, tj.
2-metoksi-4-(prop-2-en-1-il)fenol dobiven je parnom destilacijom iz suhih cvjetova klinčića. Pregrađivanje eugenola u izoeugenol, tj. 2-metoksi-4-(prop-1-en-1-il)fenol izvedeno je reakcijom s KOH i etilen-glikolom. Izoeugenol se koristio kao početni spoj za elektrokemijsku epoksidaciju uz bromidni medijator. Elektrokemijska reakcija izvedena je pri različitim uvjetima gdje se mijenjalo otapalo, masa, vrsta elektrodnog materijala, naboj i gustoća struje. Napravljeni su UV-Vis i 1H NMR spektri produkata elektrokemijskih reakcija. Pri 4 od 13 uvjeta vidljivi su mogući signali željenog produkta na 1H NMR spektrima, ali jedan uvjet ističe se kao najbolji.The aim of this work was the synthesis of 2-methoxy-4-(3-methyloxiran-2-yl)phenol by electrochemical epoxidation with bromide mediator. Eugenol, ie.
2-methoxy-4-(prop-2-en-1-yl)phenol was obtained from dried clove flowers by steam distillation. Rearrangement of eugenol into isoeugenol, ie.
2-methoxy-4-(prop-1-en-1-yl)phenol was performed by reaction with KOH and ethylene glycol. Isoeugenol was used as starting material for electrochemical epoxidation with bromide mediator. Electrochemical reaction was performed under different conditions in which solvent, masss, type of electrode material, charge and current density were varied. UV-Vis and
1H NMR spectra were obtained for products of electrochemical reactions. 1H NMR spectra indicate that in 4 out of 13 conditions there are possible signals for desired product, but one condition gives the best results
Electrochemical characterization of Prussian blue films on carbon electrodes
No full textBiosenzori su korišteni dugi niz godina za određivanje koncentracije biomolekula. Najčešća izvedba biosenzora sadrži enzim oksidazu. Oksidaza oksidira supstrat, pri čemu nastaje oksidirani oblik supstrata i vodikov peroksid, kao sporedni produkt. Mjerenjem koncentracije vodikovog peroksida moguće je dobiti informacije o koncentraciji biomolekule. Pri tome koristimo berlinsko modrilo, koje je medijator koji selektivno katalizira redukciju vodikovog peroksida pri potencijalima bliskim 0,0 V prema Ag/AgCl elektrodi i pri tome ga detektira.
U ovom radu, berlinsko modrilo naneseno je kemijskom depozicijom, koja je spontana reakcija FeCl3 i K3[Fe(CN)6], na konvencionalnu elektrodu od staklastog ugljika, komercijalnu sitotiskanu elektrodu i inkjet ispisanu grafensku elektrodu tijekom različitih vremena depozicije. Deponirani sloj berlinskog modrila elektrokemijski je karakteriziran cikličkom voltametrijom u KCl te u fosfatnim puferima, te je ispitana pH-ovisnost odziva. Nakon provedenih cikličkih voltametrija, na ispisanim elektrodama je provedena kronoamperometrijska detekcija otopina vodikovog peroksida različitih koncentracija kako bi se provjerila funkcionalnost potencijalnih biosenzora. Cilj rada bio je odrediti optimalne uvjete depozicije berlinskog modrila za korištenje u biosenzorima.Biosensors have been used for many years to determine the concentration of biomolecules. The most used configuration of biosensors is that involving the use of oxidase enzymes. Oxidase enzymes oxidize the substrate and produce an oxidized form of the substrate and hydrogen peroxide as a side product. The measurement of H2O2 concentration can provide information about the concentration of the target analyte. That is the reason why Prussian Blue is used, because it is a mediator that can selectively catalyze the reduction of hydrogen peroxide at an applied potential around 0,0 V vs Ag/AgCl and that way it can detect hydrogen peroxide. In this work, Prussian Blue was deposited chemically, by mixing FeCl3 and K3[Fe(CN)6] and drop casting the reaction mixture on a conventional glassy carbon electrode, commercial carbon-based screen-printed electrodes and in-house inkjet printed graphene electrodes with different times of deposition. Chemically deposited Prussian Blue layers were characterized electrochemically via cyclic voltammetry in KCl and phosphate buffers and the pH-response was evaluated. After recording cyclic voltamograms, chronoamperometric detection of hydrogen peroxide was conducted on printed electrodes to check the functionality of deposited layers. The goal of this work was to find optimal deposition conditions for biosensing applications
Photocatalytic decomposition of organic pollutants supported by a magnetic field
No full textFotokatalitički procesi u posljednjem desetljeću pronalaze sve veću primjenu u zaštiti okoliša. Nova istraživanja u ovom području sve su više usmjerena na ekološki prihvatljive metode razgradnje organskih onečišćivala u vodi, tlu te zraku te se posebno učinkovitom pokazala upravo heterogena fotokataliza s obzirom na svoje brojne prednosti. Cilj ovog rada bio je istražiti učinak magnetskog polja na potencijalno poboljšanje razgradnje organskih onečišćivala procesom fotokatalize. U uvodnom dijelu objašnjen je mehanizam fotokatalize te je opisan TiO₂ fotokatalizator koji je i dalje najčešće korišten fotokatalizator u praksi iako se koriste i različiti drugi. Navedeni su i najčešće korišteni fotokatalitički reaktori te potencijalni smještaj fotokatalizatora u njima o čemu će uvelike ovisiti i učinkovitost samog fotokatalitičkog procesa. Osim o položaju fotokatalizatora, na učinkovitost fotokatalize može se utjecati i različitim čimbenicima pa je tako istraživan i učinak temperature, početne koncentracije reaktanata, intenziteta i vrste zračenja, koncentracije kisika itd. na fotokatalizu. U radu je detaljno opisan učinak magnetskog polja na učinkovitost fotokatalize, odnosno na razgradnju organskih onečišćivala. Otkriveno je da magnetsko polje na fotokatalizu može utjecati na tri načina: induciranjem Lorentzove sile, regulacijom polarizacije spina elektrona te odvajanjem parova elektron – šupljina pomoću magnetootpora. U završnom dijelu rada ispitan je učinak magneta različite izvedbe i jačine na razgradnju različitih organskih onečišćivala te je zaključeno da magnetsko polje pozitivno djeluje na učinkovitost fotokatalitičke razgradnje jer se konstanta brzine reakcije povećala u prosjeku oko 50 %. Daljnjim razvojem fotokatalize i otkrivanjem novih fotokatalizatora moći će se utjecati na sve aktualnije probleme vezane uz stanje okoliša i energetske probleme čime će se poboljšati kvaliteta ljudskog života.Photocatalytic processes have found increasing applications in environmental protection over the past decade. New research in this field is increasingly focused on environmentally friendly methods for the degradation of organic pollutants in water, soil, and air. Heterogeneous photocatalysis has proven particularly effective, given its numerous advantages. The aim of this paper was to investigate the effect of a magnetic field on the potential improvement of organic pollutant degradation through the photocatalysis process. The introductory section explains the mechanism of photocatalysis and describes the TiO₂ photocatalyst, which remains the most commonly used in practice, although various others are also utilized. The most commonly used photocatalytic reactors and the potential placement of the photocatalyst within them are discussed, as these factors greatly influence the efficiency of the photocatalytic process. In addition to the position of the photocatalyst, various factors can affect the efficiency of photocatalysis, such as temperature, initial concentration of reactants, intensity and type of radiation, oxygen concentration, and more. The paper provides a detailed description of the effect of the magnetic field on the efficiency of photocatalysis, specifically on the degradation of organic pollutants. It was discovered that the magnetic field can influence photocatalysis in three ways: by inducing the Lorentz force, regulating electron spin polarization, and separating electron-hole pairs via magnetoresistance. In the concluding part of the paper, the effect of magnets of different designs and strengths on the degradation of various organic pollutants was examined, and it was concluded that the magnetic field positively affects the efficiency of photocatalytic degradation, as the reaction rate constant increased by approximately 50% on average. Further development of photocatalysis and the discovery of new photocatalysts could address increasingly pressing issues related to environmental and energy problems, thereby improving the quality of human life
Photothermal catalysis
No full textGlobalna potražnja za energijom brzo raste uslijed porasta svjetske populacije i intenzivne industrijske proizvodnje. Trenutno, tradicionalna fosilna goriva (nafta, prirodni plin i ugljen) i dalje predstavljaju glavni izvor energije u svijetu. Međutim, velika potrošnja fosilnih goriva može prouzročiti ozbiljne ekološke probleme i dovesti do značajnih emisija ugljika. Zbog toga, uloženo je mnogo truda u istraživanje i razvoj obnovljivih izvora energije, poput solarne energije. Fototermalna kataliza je moderna i interdisciplinarna djelatnost koja kombinira principe fotokatalize i termalne katalize kako bi se poboljšala učinkovitost kemijskih reakcija. U ovom radu istražuje se kako svjetlost i toplina zajedno djeluju na katalizatore s ciljem pokretanja i ubrzavanja kemijskih procesa. Naglasak je na razvoju novih katalizatora koji mogu istovremeno apsorbirati svjetlost i toplinsku energiju, čime se omogućava veća reaktivnost i selektivnost tijekom reakcija. Cilj ovog rada je analizirati mehanizme fototermalne katalize, usporediti različite katalitičke materijale i sustave koji se koriste u fototermalnim sustavima te identificirati njihove prednosti i izazove u primjeni. Također, analiziraju se primjene fototermalne katalize u industriji, poput proizvodnje goriva, pročišćavanja okoliša i sinteze kemikalija. Rezultati pokazuju da fototermalna kataliza značajno ubrzava kemijske reakcije u odnosu na tradicionalne termalne ili fotokatalitičke metode. Opisani su ključni katalitički materijali sa prihvatljivim fototermalnim značajkama, u koje se ubrajaju metalne nanočestice i poluvodički kompoziti. Također su identificirani čimbenici koji utječu na učinkovitost sustava, kao što su veličina čestica, specifična površina i optičke značajke katalizatora. U radu su također navedeni ključni pravci budućih istraživanja, uključujući razvoj novih katalitičkih materijala, poboljšanje stabilnosti katalizatora i integraciju fototermalnih sustava u postojeće industrijske procese. Ova istraživanja pridonose boljem razumijevanju fototermalne katalize i njezinoj primjeni u razvoju ekološki prihvatljivih i energetski učinkovitijih tehnologija.The global demand for energy is rapidly increasing due to the growth of the world's population and intensive industrial production. Currently, traditional fossil fuels (oil, natural gas, and coal) still represent the primary source of energy worldwide. However, the extensive consumption of fossil fuels can lead to serious environmental problems and significant carbon emissions. Consequently, considerable efforts have been made in researching and developing renewable energy sources, such as solar energy. Photothermal catalysis is a modern and interdisciplinary field that combines the principles of photocatalysis and thermal catalysis to enhance the efficiency of chemical reactions. This paper explores how light and heat interact with catalysts to initiate and accelerate chemical processes. The focus is on developing new catalysts capable of simultaneously absorbing light and thermal energy, thereby enabling greater reactivity and selectivity in reactions. The goal of this paper is to analyze the mechanisms of photothermal catalysis, evaluate the various materials and systems used, and identify their advantages and challenges in application. The applications of photothermal catalysis in industry, such as fuel production, environmental purification, and chemical synthesis, are also analyzed. The results show that photothermal catalysis significantly accelerates reactions compared to traditional thermal or photocatalytic methods. Key materials with high photothermal properties, including metal nanoparticles and semiconductor composites, have been identified. Factors influencing system efficiency, such as particle size, specific surface area, and optical properties of the catalysts, have also been identified. The paper also recognizes key areas for further research, including the development of new materials, improving catalyst stability, and integrating photothermal systems into existing industrial processes. These studies contribute to a better understanding of photothermal catalysis and its application in the development of more environmentally friendly and energy-efficient technologies
Determination of pseudoestrogenic compounds in real samples of thermochromic inks
No full textCilj ovog rada bio je odrediti maseni udio traženih analita, bisfenola A, benzofenona i
4,4'-(4-metilpentan-2,2-diil)difenola u uzorcima termokromnih boja te u uzorcima otisaka termokromne boje na papir kao i u uzorcima otisaka termokromne boje na papiru nakon izlaganja uvjetima anaerobne razgradnje u tlu. U ovom radu analizirani su uzorci četiri termokromne boje: Green curing flexo 25C UV, Red 75/80 irreversible, Magenta MB 60 i Blue-2 W50-0. Od navedenih uzoraka određeno je da samo boja Green curing flexo 25C UV sadrži traženi analit 4,4'-(4-metilpentan-2,2-diil)difenol u masenom udjelu od 0,1 % te također sadrži 0,7 % bisfenola A. U ostalim uzorcima nisu pronađeni traženi analiti. Potom je slijedila analiza uzorka Offset green to yellow otisnutog na više vrsta papira, bezdrvni premazani (BP), bezdrvni nepremazani (BN), te 33 % reciklirani (R33). Ovi uzorci bili su izloženi anaerobnoj razgradnji u tlu tako da je za svaku vrstu papira provedena analiza za sljedeći broj dana trajanja anaerobne razgradnje u tlu: 14, 32, 50 te 80 dana. Ovom analizom utvrđeno je da udio analita 4,4'-(4-metilpentan-2,2-diil)difenola raste u opisanim uvjetima anaerobne razgradnje u tlu.The aim of this work was to determine concentration of selected analytes which are bisphenol A, benzophenone and 4,4'-(4-methylpentane-2,2-diyl)diphenol in thermochromic printing inks and in their prints on papers which have also been exposed to anaerobic decomposition in soil. In this analysis four samples of thermochromic printing ink have been analyzed: Green curing flexo 25C UV, Red 75/80 irreversible, Magenta MB 60 and
Blue-2 W50-0. From the analysis of these samples it was found that only sample Green curing flexo 25C UV has selected analytes: 4,4'-(4-methylpentane-2,2-diyl)diphenol in mass fraction of 0,1 % and 0,7 % of bisphenol A. Other samples were found to be free from selected analytes. Then the analysis of thermochromic prints on paper using Offset green to yellow ink followed. The prints were made on various types of papers: wood-free coated (BP), wood-free uncoated (BN) and 33 % recycled (R33). Samples of these printed papers were subjected to anaerobic decomposition in soil, which was terminated at different time periods: 14, 32, 50 and 80 days. In these analyses, it was found that concentration of analyte 4,4'-(4-methylpentane-2,2-diyl)diphenol rises in described conditions of anaerobic decomposition in soil
Determination of gel-time of epoxy resins
No full textCilj ovog rada bio je odrediti vrijeme geliranja uzoraka sastavljenih od različitih epoksidnih smola i umreživala. Osim toga, zadatak je bio odrediti primjenjivost metoda za laboratorijske vježbe. Kao smole korištene su DGEBA i komercijalna (Presto) smola, a kao umreživala amini etilendiamin (EDA) i Jeffamine D400 te komercijalno (Presto) umreživalo. Metode korištene za određivanje vremena geliranja su diferencijalna pretražna kalorimetrija, test izvlačenja niti te praćenje promjene temperature uzorka s vremenom u izoliranom sustavu. Rezultati su pokazali da najbrže geliraju uzorci u kojima je kao umreživalo korišten EDA te da se rezultati općenito najbrže dobivaju praćenjem geliranja u izoliranom sustavu. Nijedna od metoda nije primjenjiva za laboratorijske vježbe.The purpose of this work was to determine the gelation time of samples composed of different epoxy resins and crosslinkers. Besides, the purpose was to determine applicability of the methods for laboratory exercises. DGEBA and commercial (Presto) resin were used as resins, while amines ethylenediamine (EDA) and Jeffamine D400, as well as commercial (Presto) crosslinker were used as crosslinkers. Methods used for determination of gel-time were differential scanning calorimetry, thread pull-out test and monitoring the temperature change of the sample with time in an isolated system. The results showed that the samples in which EDA was used as crosslinker gel the fastest, and that the results in general are obtained the fastest by monitoring the gelation in an isolated system. None of the methods are applicable for laboratory exercises