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U ovom radu predloženo je i primijenjeno šest novih matematičkih modela temeljenih na poluempirijskom proračunu za karakterizaciju procesa sušenja u pećnici kompozita cementne žbuke ojačane celuloznim vlaknima (CMCRCF). Pokusi sušenja provedeni su pri četiri razine temperature sušenja u pećnici (70, 85, 105 i 120 °C) s četiri različita udjela celuloznih vlakana (0, 5, 10 i 20 %). Dobiveni rezultati uspoređeni su s onima dobivenim regresijskom analizom šest najčešće primjenjivanih matematičkih modela sušenja (Newton, Page, Page modified1, Page modified2, Handerson Pabis i Logarithmic) uz šest predloženih modela. Regresijska točnost procesa sušenja procijenjena je koeficijentom determinacije (R2), srednjom kvadratnom pogreškom (MSE), korijenom srednje kvadratne pogreške (RMSE) i srednjom apsolutnom pogreškom (MAE). Primijenjeni su i dodatni kriteriji da bi se osigurala veća valjanost odabranih modela. Dobivene vrijednosti pokazuju dobro slaganje predloženog modela MR9 s eksperimentalnim vrijednostima, što znači da predloženi model može jasno interpretirati eksperimentalne podatke o sušenju i predvidjeti suho stanje CMCRCF-a. In this paper, six novel mathematical models based on semi-empirical calculus are proposed and applied to characterise the oven-drying process of cement mortar composites reinforced with cellulosic fibres (CMCRCFs). The drying experiments were carried out on four levels of oven-drying temperatures (70, 85, 105, and 120 °C), with four different cellulosic fibres content (0, 5, 10, and 20 %). Obtained results were compared to those derived by regression analysis of six most typically used mathematical drying models (Newton, Page, Page modified1, Page modified2, Handerson Pabis, and Logarithmic) in addition to six proposed models. The regression accuracy of the drying process was evaluated by the coefficient of determination (R2), low mean square error (MSE), low root mean squared error (RMSE), and mean absolute error (MAE). Additional criteria were used to ensure more validity of the selected models. The obtained values indicate a highly accurate fit of the proposed model MR9, meaning that the proposed model can clearly interpret the experimental drying data and predict the dry state of CMCRCFs.

Prisutnost farmaceutika u vodama problematična je iz više aspekata, uglavnom zbog njihove specifične prirode djelovanja u sustavu u kojem se nalaze te pripadajućih fizikalno kemijskih karakteristika koje ih čine postojanim i otpornim na razgradnju. Osim toga, skloni su bioakumulaciji u vodenom okolišu te mogu imati toksičan učinak na žive organizme. Ta grupa onečišćivala redovito je detektirana u konvencionalnim sustavima za obradu otpadnih voda. Uklanjanje farmaceutika iz voda konvencionalnim primarnim i sekundarnim metodama (filtracija, taloženje, biološka obrada) nije zadovoljavajuće, pa se sve više razvijaju i primjenjuju napredni postupci, u koje spadaju membranske i oksidacijske tehnologije. Najveća prednost membranskih tehnologija je njihova visoka razina industrijske primjene uz zadovoljavanje najviših standarda za vode. Napredni oksidacijski postupci karakteristični su po mogućnosti razgradnje složenih onečišćivala do jednostavnijih te mineralizaciji organskih onečišćivala u otpadnim vodama uz malo ili gotovo nikakvo nastajanje sekundarnog otpada. U svrhu daljnjeg poboljšanja njihovih prednosti, ali i otklanjanja nedostataka, te se tehnologije sve češće međusobno nadopunjuju i kombiniraju, što rezultira povećanjem učinkovitosti uklanjanja farmaceutika iz voda i smanjenjem njihove toksičnosti. The presence of pharmaceuticals in the aquatic environment is problematic in many aspects, mainly due to their specific mode of action, and physical and chemical properties that make them highly resistant to degradation. This new group of contaminants is frequently detected in conventional wastewater treatment plants. Removal of pharmaceuticals from water by primary and secondary methods (filtration, sedimentation, biological treatment) is not satisfactory, therefore advanced methods involving membrane and advanced oxidation processes are increasingly being developed. The most significant advantage of membrane technologies is their wide industrial applicability while maintaining the highest water standards. Advanced oxidation processes can effectively decompose complex pollutants into simpler ones, and mineralize organic pollutants in wastewater without generating secondary waste. In order to improve their advantages, but also to eliminate disadvantages, these technologies are increasingly complemented and combined, resulting in higher efficiency in removing pharmaceuticals from water and reducing their toxicity.

Emulsions are traditionally prepared with the application of high shear forces generated by the use of static mixers, homogenisers, or ultrasound. The resulting emulsions are sensitive to change of process conditions. The application of high forces and temperatures can significantly affect the constituents of the emulsions and their final stability. Microfluidic technology seems to be a very efficient alternative to classic emulsification methods. The dimensions of microdevices in combination with continuous processes offer a great advantage over classic batch emulsification processes carried out on a larger scale. The small dimensions of the microdevices allow easy transport of equipment, better control and safety of the process, and intensified mass and energy transfer. The mixing time in microdevices is reduced to a few milliseconds because the molecules in the microchannels have a short diffusion path. In this paper, an overview of emulsification processes, the advantages of use of microfluidics in emulsification, and future perspectives of microemulsification are presented. Tradicionalno se emulzije pripremaju primjenom jakih smičnih sila koje nastaju upotrebom statičkih miješala, homogenizatora ili primjenom ultrazvuka. Tako proizvedene emulzije osjetljive su na promjenu procesnih uvjeta. Primjena jakih sila i povišenih temperatura može značajno utjecati na komponente emulzija i njihovu konačnu stabilnost. Primjena protočnih mikrosustava pokazala se učinkovitom alternativnom tehnologijom klasičnim metodama emulgiranja. Male dimenzije mikrouređaja u kombinaciji s kontinuiranom provedbom procesa omogućuje brojne prednosti u odnosu na klasične šaržne procese emulsifikacije koji se provode u većem mjerilu. Male dimenzije mikrouređaja omogućuju lakši transport opreme, bolju kontrolu i sigurnost procesa te intenzivniji prijenos tvari i topline. Vrijeme miješanja u mikrouređajima smanjeno je na nekoliko milisekundi zbog kratkog difuzijskog puta molekula u mikrokanalima. U ovom radu dan je pregled procesa emulgiranja, prednosti primjene protočnih mikrosustava u provedbi procesa emulgiranja te potencijalnih novih područja primjene te tehnologije.

The impact of molybdenum (Mo) and tungsten (W) on improving the catalytic characteristics of the chromium-based catalyst, Cr2O3, was explored in this study. The use of semi-empirical and density functional theory computational methods was deployed to understand the impact of the substitution of the chromium (Cr) with Mo and W on the catalyst, CrXO3 (where X = Cr, Mo, W) in the production of propylene from propane. Findings from the investigation confirmed that the surface modified with Mo showed better potential for improving the catalyst selectivity, retarding propylene dehydrogenation, cracking, and coking path than W, which offered a lower selectivity. The use of Mo was found to have better facilitated the propylene production due to its lower affinity for coke and cracking promoting adsorbates accounted for its sites, including easier desorption of propylene and higher barrier of deep dehydrogenation for preventing the production of undesired products, unlike the use of W. This study, therefore, recommends the use of Mo for the improvement of the catalyst that could result in better propylene yield, which could aid in meeting its rising market demand. S ciljem poboljšanja karakteristika katalizatora na bazi kroma, u ovom su se istraživanju kombinirano primijenile poluempirijske računalne metode i metode temeljene na teoriji funkcionala gustoće. Nastojao se dobiti uvid u katalitički potencijal izmjene kroma molibdenom i volframom u katalizatoru CrXO3 (gdje X označava krom, molibden i volfram) za dehidrogeniranje propana pri proizvodnji propilena. Rezultati su potvrdili da površina modificirana molibdenom pokazuje bolju selektivnosti u usporedbi s površinom modificiranom volframom, usporavajući dehidrogenaciju, pucanje i koksiranje propilena. Utvrđeno je da upotreba molibdena olakšava proizvodnju propilena zbog njegova nižeg afiniteta prema adsorbatima koji potiču pucanje i koksiranje, uključujući i lakšu desorpciju propilena te višu barijeru potpune dehidrogenacije što sprječava nastanak neželjenih produkata; to nije bio slučaj kod volframa. Ovo istraživanje stoga preporučuje upotrebu molibdena za poboljšanje svojstava katalizatora, što bi moglo rezultirati većim iskorištenjem u proizvodnji propilena te pomoći zadovoljavanju rastuće tržišne potražnje za propilenom.

Ash is a by-product of wood biomass combustion that must be removed daily from stoves or fireplaces. Therefore, operators or owners are exposed to the potential impact of ash. The goal of this study was to determine whether heavy metal present in wood pellet ash posed a health concern to stove operators/owners. The risk assessment procedure was carried out in several steps, including exposure evaluation, toxicity evaluation, and risk categorisation. The hazard coefficient (HQ) and non-carcinogenic hazard index (HI) were calculated for Cd, Cr, Cu, Ni, Pb, and Zn. HQ had the highest value for the ingestion pathway (3.62 ∙ 10–6), and the value for non-carcinogenic HI was 3.70 ∙ 10–6. The value HI < 1 suggests that there is no risk to operator health related to heavy metals in analysed wood pellets ash. The carcinogenic risk (CR) was calculated for Ni, Pb, Cr, and Cd, and the values were within the permitted limits. The risk assessment based on HI and CR indicators proved that there was no significant health concern regarding exposure to the analysed ashes. Pepeo je nusproizvod izgaranja drvne biomase koji se svakodnevno mora uklanjati iz peći ili kamina. Stoga su operateri ili vlasnici izloženi potencijalnom utjecaju pepela. Ovo istraživanje ima cilj procijeniti zdravstveni rizik izloženosti operatera/vlasnika pepelu drvenih peleta zbog sadržaja teških metala. Postupak procjene rizika proveden je u nekoliko koraka uključujući procjenu izloženosti, procjenu toksičnosti i kategorizaciju rizika. Izračunati su koeficijent opasnosti (HQ) i indeks nekarcinogene opasnosti (HI) za Cd, Cr, Cu, Ni, Pb i Zn. HQ je imao najveću vrijednost za izloženost putem gutanja (3.62 ∙ 10–6), a vrijednost za nekarcinogeni HI bila je 3.70 ∙ 10–6. Vrijednost HI < 1 ukazuje na to da sadržaj teških metala u analiziranom pepelu ne predstavlja rizik za zdravlje operatera. Karcinogeni rizik (CR) izračunat je za Ni, Pb, Cr i Cd, a vrijednosti su bile unutar dopuštenih granica. Rizik procijenjen primjenom HI i CR pokazatelja potvrdio je da ne postoji značajna opasnost za zdravlje osoba koje dolaze u kontakt s analiziranim pepelom.

The aim in this work was to investigate the change in microstructure, phase transformation temperatures, and thermal properties due to the quenching of the investigated Cu-Al-Mn and Cu-Al-Mn-Ti alloys in ribbon form. This paper presents the results of microstructure analysis and thermal properties of Cu-Al-Mn and Cu-Al-Mn-Ti shape memory alloys produced in ribbon form by melt spinning technique. The microstructural analysis was carried out before and after quenching. After casting of the investigated alloys, annealing at 900 °C for 30 min was performed, followed by water quenching. The microstructural analysis was carried out by optical and scanning electron microscopy equipped with an energy dispersive spectrometer and by X-ray diffractometer. Thermodynamic calculation of a ternary Cu-Al-Mn system in equilibrium condition was performed using Thermo-Calc 5 software. Phase transformation temperatures were determined by differential scanning calorimetry and electrical resistance measuring. The results of microstructural analysis show the presence of martensite microstructures before and after quenching in the Cu-Al-Mn alloy, while in the Cu-Al-Mn-Ti alloy martensite microstructure exists only after quenching. Phase transformation temperatures decreased after quenching and titanium addition. Cilj rada bio je istražiti promjene u mikrostrukturi, temperaturama transformacije i toplinskim svojstvima nastale uslijed kaljenja Cu-Al-Mn i Cu-Al-Mn-Ti legura u obliku trake. U radu su prikazani rezultati mikrostrukturne analize i toplinskih svojstava Cu-Al-Mn i Cu-Al-Mn-Ti legura s prisjetljivosti oblika proizvedenih u obliku trake postupkom melt spinning. Mikrostrukturna analiza je provedena prije i nakon kaljenja. Nakon lijevanja istraživane legure su žarene pri 900 °C u trajanju 30 minuta, nakon čega je slijedilo kaljenje u vodi. Mikrostrukturna analiza je provedena optičkim i pretražnim elektronskim mikroskopom opremljenim energetsko disperzijskim spektroskopom te rendgenom. Termodinamički proračun ternarnog Cu-Al-Mn sustava proveden je u ravnotežnim uvjetima pomoću Thermo-Calc 5 programskog paketa. Temperature fazne transformacije određene su diferencijalnom pretražnom kalorimetrijom i mjerenjem električnog otpora. Rezultati mikrostrukturne analize pokazuju prisutnost martenzitne mikrostrukture prije i nakon kaljenja Cu-Al-Mn legure, dok u Cu-Al-Mn-Ti leguri martenzitna mikrostruktura postoji samo nakon kaljenja. Temperature faznih transformacija smanjuju se nakon kaljenja i dodatka titana.

As part of a comprehensive evaluation of post-treatment techniques for the removal of chemical and microbiological pollutants from lagoon effluents, an aerated biofilter was designed. The main objective of this study was to evaluate the performance of pozzolan and Luffa cylindrica as low-cost packing materials for the advanced treatment of Stidia natural lagoon effluent. The aerated biofilter operates in down-flow with HLRs of 11.37 to 28.43 m3 m–2 d–1 and an air/liquid flow ratio of 3 : 1. The different experiments performed on the pilot showed that the percentages of sCOD removal vary with the HLRs and the wastewater concentration at the biofilter inlet. In this study, sCOD removal efficiencies above 78.9 % were achieved depending on HLR, and a maximum removal efficiency of TSS of 71.5 % was obtained for 28.43 m3 m–2 d–1. At low HLR (11.37 m3 m–2 d–1), the treated effluent had the following average concentrations: sCOD of 29.5 mg l–1, BOD5 of 21.7 mg l–1 and TSS of 26.4 mg l–1. These experimental results were used with an empirical model to determine the media constant n and treatability factor K. The faecal coliforms and Escherichia coli detected in the treated effluent were less than 105 CFU/100 ml, which meet the national guidelines for wastewater reuse in irrigation. U sklopu sveobuhvatne procjene tehnika naknadnog uklanjanja kemijskih i mikrobioloških onečišćenja iz efluenta laguna, projektiran je aerirani biofiltar. Glavni cilj ovog istraživanja bio je procijeniti učinak pucolana i biljke Luffa cylindrica kao jeftinih punila za naprednu obradu efluenta prirodne lagune Stidia. Aerirani biofiltar radi s brzinom hidrauličkog opterećenja (HLR) od 11,37 do 28,43 m3 m–2 d–1 i omjerom protoka zrak/tekućina od 3 : 1. Eksperimenti provedeni na pilotu pokazuju da smanjenje KPK (izražene s obzirom na otopljene tvari) varira ovisno o HLR-u i koncentraciji otpadne vode na ulazu u biofiltar. U ovom istraživanju postignute su učinkovitost smanjenja KPK iznad 78,9 % ovisno o HLR-u, a maksimalna učinkovitost uklanjanja ukupnih suspendiranih čestica (TSS) od 71,5 % dobivena je pri 28,43 m3 m–2 d–1. Pri niskom HLR-u (11,37 m3 m–2 d–1), KPK, BPK5 i TSS obrađene otpadne vode iznosili su 29,5 mg l–1, 21,7 mg l–1 odnosno 26,4 mg l–1. Ti eksperimentalni rezultati korišteni su u empirijskom modelu da bi se odredila konstanta medija n i faktor obrade K. CFU vrijednosti fekalnih koliforma i bakterije Escherichia coli u obrađenoj otpadnoj vodi bile su ispod 105 CFU/100 ml što zadovoljava nacionalne smjernice za upotrebu tih voda u navodnjavanju zemljišta.

The emergence of COVID-19 has caused worldwide concern due to its high infectivity and mortality. Research groups around the world have prioritised drug development against COVID-19. Repurposing of already approved drugs, including the antimalarial drug chloroquine, has attracted considerable attention. The aim of this article is to (i) provide an overview of the recent chemical methods used to synthesise chloroquine and hydroxychloroquine, and (ii) provide insight into the data collected in 2020 on their efficacy against COVID-19. Unfortunately, the promising early results have not been confirmed and a clear and unambiguous conclusion on their clinical efficacy has not yet been drawn.

The content of micro- and macroelements in dry wild and edible Morchella esculenta and Lactarius piperatus mushrooms collected in Bosnia and Herzegovina was determined using the ICP-OES (inductively coupled plasma optical emission spectrometry) technique. The contents of microelements in M. esculenta and L. piperatus expressed in mg kg–1 DW (dry weight) were as follows: Co 0.08 and 0.28, Cu 37.35 and 27.66, Fe 174.29 and 28.11, Mn 21.26 and 19.31, Se 0.46 and 0.52, Zn 122.84 and 45.06, Al 27.80 and 24.80, Cr 0.83 and 1.06, Ni 0.99 and 0.96, As 0.32 and 0.09, Cd 0.48 and 0.13, and Pb 0.61 and 0.12, respectively, while the contents of macroelements were: K 26989.48 and 36117.20, Na 70.85 and 28.60, Ca 643.48 and 271.93, Mg 684.16 and 840.64, S 2329.33 and 610.42, and P 10339.35 and 5107.63, respectively. In this study, the potential health risks of heavy metals were assessed, and target hazard quotient (THQ) for As, Cd, Pb, Cu, Zn, Ni, and Cr in the tested mushrooms was lower than the safe level. Edible wild mushrooms M. esculenta and L. piperatus, according to this study, could be used in human nutrition due to their favourable characteristics. Based on the accumulations of heavy metals in the tested mushrooms, it was shown that the collection surfaces are environmentally acceptable. Mushrooms collected from this area are generally safe to eat and pose no health risks to humans. Sadržaj mikro i makroelemenata u sušenim divljim jestivim gljivama Morchella esculenta i Lactarius piperatus prikupljenim u Bosni i Hercegovini određen je tehnikom ICP-OES (induktivno spregnuta plazma s optičkom emisijskom spektrometrijom). Sadržaj mikroelemenata kod M. esculenta i L. piperatus izražen u mg kg–1 suhe težine bio je sljedeći: Co 0,08 i 0,28, Cu 37,35 i 27,66, Fe 174,29 i 28,11, Mn 21,26 i 19,31, Se 0,46 i 0,52, Zn 122,84 i 45,06, Al 27,80 i 24,80, Cr 0,83 i 1,06, Ni 0,99 i 0,96, As 0,32 i 0,09, Cd 0,48 i 0,13, te Pb 0,61 i 0,12, dok je sadržaj makroelemenata bio: K 26989,48 i 36117,20, Na 70,85 i 28,60, Ca 643,48 i 271,93, Mg 684,16 i 840,64, S 2329,33 i 610,42, te P 10339,35 i 5107,63. U ovom radu procijenjeni su potencijalni zdravstveni rizici teških metala, a kvocijent ciljane opasnosti (THQ) za As, Cd, Pb, Cu, Zn, Ni i Cr u ispitivanim gljivama bio je niži od sigurnosne razine. Prema rezultatima istraživanja, divlje jestive gljive M. esculenta i L. piperatus, zbog svojih povoljnih karakteristika, mogle bi se upotrebljavati u ljudskoj prehrani. Podatci o akumuliranosti teških metala u ispitivanim gljivama pokazali su da su sabirne površine ekološki prihvatljive, a gljive sigurne za jelo.

Microbial bile salt hydrolases (BSHs) catalyse the hydrolysis of glycine and taurine-linked bile salts in the small intestine of humans. Achieving the effects of structural changes in BSH molecules on biocatalytic efficiency (kcat/Km) and activation energy (Ea) is necessary to determine biocatalytic performances of the enzymes. Amino acids responsible for biocatalytic activity or substrate specificity in BSH molecules were modified to determine the effects of structural changes on kcat/Km values and Ea values of the bioconversion reactions. Purified wild type positive control enzyme (pCON2) and mutant recombinant target enzymes (F18L and Y24L) reacted with six conjugated pure bile salt substrates at working temperature and pH conditions. The results of the hydrolysis conversion analysis conducted at various pH conditions were used to estimate kcat/Km, and the assays conducted at various temperature conditions were used to approximate Ea of the biocatalytic reactions. The quantified kcat/Km value was found remarkably highest with mutant recombinant enzymes (Y24L), while the efficiency value with wild type (pCON2) was determined as lowest, indicating that the structural modifications in BSH molecules showed higher values. The alterations with the mutant-type enzymes F18L and Y24L resulted in decreasing kcat/Km and increasing Ea estimations of the hydrolysis conversion reactions. Mikrobne hidrolaze žučnih soli (BSH) kataliziraju hidrolizu soli glicina i taurina u tankom crijevu ljudi. Aminokiseline odgovorne za biokatalitičku aktivnost ili specifičnost supstrata u BSH molekulama modificirane su da bi se odredio utjecaj strukturnih promjena BSH molekula na biokatalitičku učinkovitost (kcat/Km) i energiju aktivacije (Ea) reakcija biokonverzije. Pročišćen prirodni enzim pCON2, upotrijebljen kao kontrola, a mutantni enzimi (F18L i Y24L) reagirali su sa šest čistih supstrata konjugiranih žučnih soli pri radnim uvjetima pH i temperature. Eksperimenti provedeni pri različitim pH vrijednostima primijenjeni su u procjeni kcat/Km vrijednosti biokatalitičkih reakcija, dok su eksperimenti provedeni pri različitim temperaturama primijenjeni u aproksimaciji njihovih Ea vrijednosti. Iznos kcat/Km bio je najveći kod mutantnih enzima (Y24L), a najniži kod kontrole (pCON2), što ukazuje da su strukturne modifikacije u BSH molekulama povezane s većom učinkovitosti. Preinake kod mutantnih enzima F18L i Y24L rezultirale su smanjenjem vrijednosti kcat/Km te povećanjem procijenjene Ea vrijednosti reakcija hidrolize.