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The peel of the Okitsu variety of mandarin is created as a by-product of the fruit’s growth and processing. The primary goal of this research was to use a unique nonthermal extraction method (high-voltage electric discharge assisted) with green solvent (water) to valorise citrus peel as a valuable raw material. In October 2020, samples (citrus peel) were collected from the farm of Mr. Dalibor Ujević (Opuzen, Hrvatska). Samples were washed, freeze-dried, and sieved before extraction. The effects of extraction process parameters, such as treatment duration (5–15 min), frequency (40–100 Hz), and liquid to solid ratio (200–400 ml g–1) on the extraction yield and content of hesperidin and narirutin were studied. Spectrophotometric methods were used to assess the antiradical activity and total phenolic content of the extracts. Individual phenolic components were identified and quantified using HPLC method. The extraction process parameters were optimised with a commercial softer tool (Design Expert®) using experimental data gathered using the Box-Behnken experimental design. Experiments were conducted as shown in Tables 1 and 2. The extraction yield was ranked from 359.23 to 463.20, the total phenol values ranged from 96.23 to 275.46 mg GAE l–1, DPPH values ranged from 87.08 to 94.93 %. Total phenol content and antiradical activity decreased with increasing extraction time, as shown in Fig. 1. Six phenolic compounds were identified and quantified, predominated by hesperidin and narirutin (Table 3). The regression models for all tested HVED extraction responses were significant (p-value under 0.05) based on the acquired data, and the quality of the models produced was evaluated based on the coefficients of determination (R2) and Lack of Fit value. The obtained R2 values for all models developed were 0.911; 0.844, and 0.845 with a nonsignificant lack of fit, indicating an adequate relationship between input parameters (extraction conditions) and observed variable, in this case, extraction efficiency, hesperidin and narirutin content (Table 4). The obtained data was utilised to create three-dimensional (3D) response surface graphs, as shown in Figs. 2–4. The regression models within this study were predicted by Eqs. (1)–(3). With response surface methodology (RSM), optimal parameters of HVED extraction process were defined, as follows: extraction yield (285.93 ml g–1, 73.38 Hz and 14.84 min), hesperidin content (366.19 ml g–1, 97.56 Hz, and 5.1 min), and narirutin content (200 ml g–1, 70 Hz, and 15 min), as presented in Table 5, together with predicted and experimentally verified values. Konzumacija svježih citrusa, ali i njihova prerada generiraju nusproizvode, kao što su kora, sjemenke, pulpa, kao i otpadne vode. Cilj ovog istraživanja je valorizacija agroindustrijskih nusproizvoda (kore citrusa) kao vrijedne sirovine za ekstrakciju polifenola primjenom inovativne netermalne metode ekstrakcije sa zelenim otapalom (voda). U ekstraktima je kvantificirano i identificirano ukupno šest fenolnih spojeva. Pri tome je promatran utjecaj vremena (od 5 do 15 min), frekvencije (od 40 do 100 Hz) i omjera kapljevito/kruto (od 200 do 400 ml g–1) na efikasnost procesa ekstrakcije (iskorištenje) i udio dominantnih fenolnih spojeva (hesperidina i narirutina). Uz pomoć metode odzivnih površina definirani su optimalni parametri promatranog procesa ekstrakcije za svaki od istraživanih odziva, i to za iskorištenje (285,93 ml g–1, 73,38 Hz i 14,84 min), za hesperidin (366,19 ml g–1, 97,56 Hz i 5,1 min) te za narirutin (200 ml g–1, 70 Hz i 15 min). Ekstrakcija potpomognuta visokonaponskim električnim pražnjenjem (HVED ekstrakcija) pokazala se pogodnom za ekstrakciju fenolnih spojeva, pri čemu je izbjegnuta uporaba organskih otapala.

Metalurški otpad ima velik potencijal za uporabu kao adsorbens za uklanjanje teških metala iz otpadnih voda, ističući se kao mogući jeftini adsorbens. U ovom članku prikazano je adsorpcijsko ponašanje Zn(II) iona na dva kruta metalna otpadna materijala – otpadnoj kalupnoj mješavini (OKM) i otpadnoj anodnoj prašini (AP). Dobiveni rezultati pokazali su da se oba otpadna materijala mogu upotrebljavati kao potencijalni adsorbensi. Anodna prašina ima bolja adsorpcijska svojstva. Ravnotežni podatci za adsorpciju Zn(II) na otpadnim metalurškim materijalima ispitani su Freundlichovim i Langmuirovim izotermnim modelima. Utvrđeno je da je Langmuirov model prikladniji te da se adsorpcija odvija kao kemisorpcija. Metallurgical waste has great potential for use as an adsorbent for the removal of heavy metals from wastewater, standing out as possible low-cost adsorbents. This article presents the adsorption behaviour of Zn(II) ions on two solid metal waste materials – waste mould sand (WMS) and anode dust (AD). The obtained results showed that both waste materials could be used as potential adsorbents. Anode dust has better adsorption properties. The equilibrium data for the adsorption of Zn(II) on waste metallurgical materials were examined by Langmuir and Freundlich’s adsorption isotherm models. It was found that the Langmuir model is more appropriate, and that adsorption takes place as chemisorption.

With the use of fixed-dose drug combinations, the potential risk of non-adherence needs to be minimised, which is particularly important in patients with chronic diseases. The development of such dosage form is a complex process in which an important role is played by testing the physicochemical compatibility of the components intended for the manufacture of the desired product. Various analytical techniques, such as thermoanalytical (DSC, DTA), spectroscopic (FTIR, XRPD) and chromatographic (HPLC), in combination with certain degradation studies, such as forced degradation and isothermal degradation, are often used. In this review, on the example of the development of a fixed-dose combination of 5-aminosalicylate and folic acid, procedures suitable for testing the compatibility of drug components, as well as analytical techniques and various ways of interpretation of results are described. Uvođenjem fiksnih kombinacija lijekova potencijalni rizik od neadherencije nastoji se svesti na najmanju moguću mjeru, što je posebice važno kod pacijenata koji boluju od kroničnih bolesti. Razvoj takvog ljekovitog oblika složen je postupak u kojem važnu ulogu ima ispitivanje fizikalno-kemijske kompatibilnosti sastavnica predviđenih za izradu željenog proizvoda. U svrhu provedbe takvih studija često se primjenjuju različite analitičke tehnike, poput termoanalitičkih (DSC, DTA), spektroskopskih (FTIR, XRPD) te kromatografskih (HPLC) u kombinaciji s određenim studijama razgradnji, poput prisilne razgradnje i izotermalne razgradnje. U ovom radu, na primjeru razvoja fiksne kombinacije 5-aminosalicilata i folne kiseline, bit će opisani postupci prikladni za ispitivanje kompatibilnosti sastavnica lijeka kao i analitičke tehnike te razni načini interpretacije rezultata.

Životni i radni okoliš najčešće su zatvoreni prostori te je u njima potrebno osigurati zdravstvenu zaštitu ukućana i djelatnika. Neke djelatnosti traže posebnu zaštitu, pogotovo u vrijeme pandemije. Životni i radni okoliš mogu se održavati čistim i urednim na tri načina: čišćenjem, dezinfekcijom i sanitacijom. U ovom radu dan je pregled literature koja povezuje dezinfekcijska sredstva, njihovu uporabu i rezistentnost mikroorganizama na dezinfekcijska sredstva. Također, dan je prikaz kritičnih točki koje su se pojavile u različitim ispitnim laboratorijima u Republici Hrvatskoj, vezano za pandemiju COVID-19, a kao posljedica nedostatka naputaka u normama. Pretraživanje literature je provedeno temeljem ključne riječi dezinfekcija u bazama PubMed, Science Direct, Web of Science, Scopus i Google Scholar te na stranicama CDC-a i HZJZ-a zbog najnovijih preporuka vezano za COVID- 19 infekcije. Rezultati su pokazali da je Norma osnovni dokument ali bi za ovakve situacije trebao i specifičnu nadogradnju ovisno o tipu laboratorija i njegovoj djelatnosti kako pojedini laboratoriji ne bi donosili samostalne odluke. Temeljem identificiranih potreba i problema, državne institucije bi trebale dati detaljne upute ovisno o djelatnosti. Stoga, ovu situaciju i stečeno iskustvo treba iskoristiti i izraditi dokumente koji će biti primjenjivi u kriznim situacijama u budućnosti te na temelju kojih je moguće provesti i edukaciju osoblja o ponašanju u kriznim situacijama.

In the last fifty years, there has been a significant increase in plastic waste, which has become an increasing environmental problem due to uncontrolled dumping, with significant consequences on living ecosystems. Plastic is an important and ubiquitous material in the economy and everyday life, and nearly 26 million tonnes of plastic waste are generated annually in the countries of the European Union. About 30 % of this waste is recycled, a significant part is recovered for energy, and part is still disposed of in landfills. Recycling plastic waste preserves natural raw materials such as oil and natural gas, which are used to produce plastic materials, and reduces emissions into the environment and energy consumption. Under the Resource Efficient Europe Plan, plastic waste is recognised as an important raw material for the production of new products, and is one of the key raw materials in the transition to a circular economy. This paper presents general possibilities for recycling plastic waste. Based on the indicative examination results of the composition of separately collected plastic waste in Zagreb, an assessment of the possibility of its recycling is given. In the Republic of Croatia, plastic waste is a major problem since it is inadequately sorted, and therefore represents a significant financial burden for utility companies that manage it within public service of municipal waste collection. U zadnjih pedesetak godina zabilježen je značajan rast količina plastičnog otpada koji nekontroliranim odbacivanjem postaje sve veći problem za okoliš i sa značajnim posljedicama na živuće ekosustave. Plastika je važan i sveprisutan materijal u gospodarstvu i svakodnevnom životu i godišnje u zemljama Europske unije nastaje blizu 26 milijuna tona plastičnog otpada. Oko 30 % tog otpada se reciklira, znatan dio se energetski oporabljuje, a dio se još uvijek odlaže i na odlagališta otpada. Recikliranjem plastičnog otpada čuvaju se prirodne sirovine kao što su nafta i zemni plin koje se upotrebljavaju za proizvodnju plastičnih materijala te se smanjuju emisije u okoliš i potrošnja energije. Planom za resursno učinkovitu Europu, plastični otpad prepoznat je kao važna sirovina za proizvodnju novih proizvoda i jedna je od ključnih sirovina u prelasku na kružno gospodarstvo. U ovom je radu dan prikaz općih mogućnosti recikliranja tj. oporabe plastičnog otpada. Na temelju indikativnih rezultata ispitivanja sastava odvojeno prikupljenog plastičnog otpada u Zagrebu dana je procjena mogućnosti njegove reciklaže. U Republici Hrvatskoj plastični otpad velik je problem budući da se adekvatno ne sortira. Zbog toga je značajno financijsko opterećenje komunalnim društvima koja njime gospodare u sklopu javne usluge prikupljanja komunalnog otpada.

Shortly after introduction of commercial automatic chemical detectors, mostly based on ion mobility spectrometry technology, at the end of 20th century field devices using other chemical detection techniques (FTIR, Raman, GC-MS, surface acoustic wave, photoacoustic, electrochemical, biosensor and others) were developed. Among these techniques, portable GC-MS detectors provide very reliable qualitative and quantitative chemical analysis, but high cost of these devices, the complexity of operating with them and the complexity of sample preparation for analysis present a problem. Some chemical detection technologies cannot be used for the development of a reliable hand-held chemical detector, and not a single technique, for the time being, allows the development of a universal chemical detector. A potential solution is the development of a multi-sensor device that compensates negative sides of each of the sensors. This paper provides an overview of commercially available chemical detectors based on new generation detection technologies and an overview of scientific research focused on further development of detection with simpler, more reliable and preferably cheaper solutions is given. Ubrzo nakon uvođenja komercijalnih automatskih detektora bojnih otrova, većinom temeljenih na spektrometriji ionske pokretljivosti, krajem 20. stoljeća razvijaju se terenski uređaji koji primjenjuju i druge tehnike kemijske detekcije (FTIR, Raman, GC-MS, površinski akustični val, fotoakustične, elektrokemijske, biosenzorske i ostale). Od navedenih tehnika, prijenosni GC-MS detektori omogućuju vrlo pouzdanu kvalitativnu i kvantitativnu kemijsku analizu, no problem predstavljaju visoka cijena tih uređaja, zahtjevnost u rukovanju s njima te kompleksna priprema uzoraka. Neke tehnike kemijske detekcije nisu primjenjive za razvoj pouzdanog ručnog kemijskog detektora, a niti jedna tehnika, zasad, ne omogućuje razvoj univerzalnog kemijskog detektora. Potencijalno rješenje je razvoj višestrukog senzorskog uređaja koji bi kompenzirao negativne strane svakog od senzora. U ovom radu dan je pregled komercijalno dostupnih kemijskih detektora temeljenih na novim generacijama tehnika detekcije te pregled znanstvenih istraživanja usmjerenih na daljnji razvoj detekcije bojnih otrova s jednostavnijim, pouzdanijim i poželjno jeftinijim rješenjima.

Detection of chemical warfare agents and toxic industrial chemicals is very important for security forces. For a long time it has been based on colorimetric chemistry, and only the development of electronics has made the automation and miniaturisation of chemical detection possible. At the end of the 20th century, automatic chemical detectors, mostly based on ion mobility spectrometry technology (IMS), began to appear on the market. Nowadays, colorimetric detectors are increasingly being used again due to their excellent selectivity and low cost, and new chromogenic reagents are being developed. On the other hand, the development of IMS detectors is focused on the use of an asymmetric field since it allows smaller dimensions and greater sensitivity of the detector. In this paper, besides commercially available chemical detectors based on colorimetry and ion mobility spectroscopy techniques, an overview of scientific research focused on further development of these technologies with the goal of increasing selectivity and sensitivity is given. Detekcija bojnih otrova i toksičnih industrijskih kemikalija iznimno je važna za sigurnosne snage. Dugo se zasnivala na kolorimetrijskoj kemiji, a tek je razvoj elektronike omogućio automatizaciju i minijaturizaciju kemijske detekcije. Krajem 20. stoljeća na tržište su počeli dolaziti automatski kemijski detektori koji su se većinom temeljili na spektrometriji ionske pokretljivosti (IMS). Danas se kolorimetrijski detektori ponovno sve više upotrebljavaju zbog odlične selektivnosti i niske cijene te se razvijaju novi kromogeni reagensi. S druge strane razvoj IMS detektora fokusiran je na primjenu asimetričnog polja s obzirom na to da ono omogućava male dimenzije i veću osjetljivost detektora. U ovom radu, uz komercijalno dostupne kemijske detektore bazirane na tehnikama kolorimetrije i spektrometrije ionske pokretljivosti, dan je pregled znanstvenih istraživanja usmjerenih na daljnji razvoj tih tehnologija detekcije s ciljem povećanja selektivnosti i osjetljivosti.

Increased demand for drugs has promoted the pharmaceutical and chemical industries as the most dynamic industries of the 21st century. By using the Hofmann-Löffler-Freytag (HLF) reaction, the modification of pharmacologically active substances and biologically important compounds can be achieved in an environmentally friendly manner by highly efficient syntheses. This reaction enables the formation of new compounds according to the principles of green chemistry, without expensive metal catalysts. Numerous computational and experimental studies have shown exceptional flexibility and the possibility of optimising this method in order to increase the economy and reduce the amount of waste generated as by-products of synthetic processes. However, the mechanism of this reaction is yet to be elucidated sufficiently, and further experiments are necessary in order to determine the thermodynamic and kinetic parameters that control and guide the HLF reaction. It is necessary to determine the influence of substituents and solvents on 1,5-HAT or 1,6-HAT regioselectivity, and to recognise the mechanism responsible for switching between the radical and ionic mechanism of the reaction. This work is licensed under a Creative Commons Attribution 4.0 International License. Hofmann-Löffler-Freytagova reakcija otkrivena je krajem 19. stoljeća, a munjeviti razvoj događa se posljednjih 20 godina. Primjenjuje se za stvaranje C−N veze na nesupstituiranim C−H pozicijama te za uvođenje pirolidinskih i piperidinskih prstenova na ekološki prihvatljiv način, bez upotrebe skupih metalnih katalizatora i uz vrlo učinkovite sinteze. U ovom pregledu prikazat će se računalne i eksperimentalne studije koje pokazuju fleksibilnost i mogućnosti optimizacije navedene metode s ciljem povećanja ekonomičnosti i smanjenja količine otpadnih tvari, po principima zelene kemije. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.

Increasingly stringent regulatory requirements, greater wastewater generation, and limited space necessitate new wastewater treatment processes. Biofilm-based treatment technologies have proven to be efficient and applicable. The results of wastewater treatment using biofilm reactors with different types of carriers and the associated community of microorganisms support their use for wastewater treatment of different origins and degradation products present. Biofilm formation begins with the adsorption of molecules on the surface to form a film that can have several effects, such as altering surface properties and suppressing or enhancing the release of toxic metal ions from the surface. Subsequently, the microorganisms begin to coalesce into a microcolony and then into a three-dimensional biofilm structure. The biofilm cells detach from the structure and form a new biofilm. Biofilm reactors are divided into three categories, which are shown in Fig. 1. Common to them is the presence of supports with formed biofilm, low sludge production, easy handling, higher concentration of active biomass, protection of microorganisms from environmental changes and allowing the growth of slow-growing microorganisms, which are important for the degradation of complex compounds. In environmental biotechnology, the planning, designing, optimising, and evaluating processes in a biological wastewater treatment plant can be done with mathematical modelling of biofilm. Mathematical models of biofilm processes are used to predict the outcome of these processes and interpret the results of biofilm research. Most experience in modelling biofilm processes in wastewater treatment is based on the operation of suspended solids reactors. In biofilm modelling, the challenge is the effect of biofilm heterogeneity on the biofilm process and the existence of a steady state in biofilm reactors. Mathematical modelling in a biofilm reactor is not straightforward due to the complexity of the biological reactions involved in substrate transformation and the lack of accurate kinetic parameters for biofilm development. The parameters required for modelling can be obtained using equations such as those in Table 1. Although modelling of biofilm reactors is not uniform, there are instructions for the most accurate modelling, so the results obtained are useful and reduce the time for modelling as well as for design/improvement of the plant and thus saving resources. The number of models available is increasing, and the choice depends on their purpose and the expertise of the operator. This work is licensed under a Creative Commons Attribution 4.0 International License. Uporaba mikroorganizama u obliku biofilma sve je češći način biološke obrade jer reaktori s biofilmom na nosačima daju zadovoljavajuće rezultate obrade otpadnih voda različitog podrijetla te se intenzivno istražuju i unaprjeđuju. Dizajn uređaja za obradu otpadnih voda, unaprjeđenje postojećih reaktora i njihove učinkovitosti te rješavanje problematičnih točaka pri obradi otpadnih voda olakšano je matematičkim modeliranjem pomoću dostupnih modela, ovisno o njegovoj svrsi. Modeliranje u praksi zahtijeva promišljanje i prilagodbu modelu i njegovim pretpostavkama te postaje nezamjenjiv dio modernih istraživanja i izgradnje sustava za obradu otpadne vode. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.

Chemistry, as well as architecture, are synthetic disciplines; keeping in mind the function of a final product, they attempt to find construction solutions to obtain a desired shape. There is certainly a difference in the object of design, as architecture is aimed at the design of buildings, and chemistry at the design of molecules, the size of their objects (macroscopic vs. submicroscopic), their nature (classical-physical systems vs. quantum systems) and, most importantly, they differ in forces a designer has to cope with (gravitation vs. electromagnetic interactions). This paper presents examples of architectural projects inspired by chemical structures (Atomium), as well as the application of chemical principles in architecture and construction of geodesic domes, devised by American architect Richard Buckminster Fuller (1895–1983). This work is licensed under a Creative Commons Attribution 4.0 International License. Kemija je, kao i arhitektura, sintetička djelatnost: imajući u vidu funkciju budućeg proizvoda, one pronalaze konstrukcijska rješenja da bi postigle željenu formu. Razlika je, dakako, u njihovom objektu, jer arhitektura dizajnira građevine, a kemija molekule, njegovoj veličini (makroskopskoj – submikroskopskoj), fizičkoj naravi (klasični fizički sustav – kvantni sustav) i, najvažnije, u silama s kojima se dizajner (arhitekt, kemičar) hvata u koštac (gravitacija – elekromagnetske interakcije). U radu su dati primjeri inspiracije arhitekata kemijskim strukturama (Atomium) te primjene načela kemijske strukture u arhitekturi (geodetske kupole R. B. Fullera). Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.