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Plan upravljanja istraživačkim podacima projekta Hrvatske zaklade za znanost BioH2
No full textPodatci koji će se prikupljati, obrađivati, stvarati i njima se ponovno koristiti prvenstveno se odnose na rezultate istraživanja koja će se provoditi u okviru projekta “Integrirani mikrosustav za enzimatsku proizvodnju biovodika (BioH2)”
Validation of a kinetic model for the biocatalytic synthesis of fluorinated cyanoalcohol in different reactor modes
No full textOptički čisti spojevi od velike su važnosti u farmaceutskoj indrustriji, uz sve veći interes za fluorirane spojeve. Za sintezu kiralnih gradivnih elemenata često se koriste enzimi halogenhidrin-dehalogenaze (HHDH), koje mogu primiti brojne anionske nukleofile, od cijanida, cijanata, tiocijanata do azida i nitrita. U njihovoj prisutnosti dolazi do reakcije otvaranja epoksidnog prstena, što dovodi do stvaranja β-substituiranog alkohola. Osnova ovog rada je biokatalitička reakcija, točnije HHDH-katalizirana reakcija otvaranja epoksidnog prstena rac-2-(4-fluorofenil)oksirana cijanidnim ionima. Uz željeni produkt (S)-3-(4-fluorofenil)-3-hidroksipropannitril, ovom reakcijom stvara se i neželjeni (R)-3-(4-fluorofenil)-3-hidroksipropannitril te rac-2-(4-fluorofenil)-1,2-etandiol. Prethodno je razvijen matematički model ove sinteze kombinacijom kinetičkih jednadžbi i reaktorskog modela. U svrhu validacije modela, provedena je serija eksperimenata u kotlastom reaktoru s različitim početnim koncentracijama epoksida, NaCN i HHDH. U eksperimentima inkubacije uočena je deaktivacija enzima ovisna o početnoj koncentraciji epoksida. Operacijska stabilnost matematički je opisana i uključena u model. Nadalje, porastom koncentracije epoksida, stabilnost enzima opada, dok cijanidni nukleofil nema značajan utjecaj na stabilnost enzima. Eksperimentalni podaci pokazuju zadovoljavajuće slaganje s ranije razvijenim matematičkim modelom. Također, matematičko modeliranje pokazalo je kako je sinteza u kotlastom reaktoru/kotlastom reaktoru s ponavljajućim dodatkom epoksida (repetitivnom šaržnom reaktoru) optimalan način proizvodnje danog spoja.Optically pure compounds are of great significance in the pharmaceutical industry, with the increasing interest in fluorinated compounds. One important enzyme group often employed in synthesizing various chiral building blocks are halohydrin dehalogenases (HHDHs) that can accept numerous anionic nucleophiles from cyanide, cyanate, thiocyanate to azide and nitrite. In their presence the ring-opening reaction of epoxide occurs, leading to β-substituted alcohol formation. The foundation of this work lies in a biocatalytic reaction, precisely HHDH-catalysed rac-2-(4-fluorophenyl)oxirane ring-opening reaction mediated by cyanide ions. Besides the desired (S)-3-(4-fluorophenyl)-3-hydroxypropanenitrile, this reaction yields an undesired (R)-3-(4-fluorophenyl)-3-hydroxypropanenitrile and rac-2-(4-fluorophenyl)-1,2-ethanediol. Mathematical model was earlier developed by coupling kinetic equations with reactor model. A series of different batch experiments varying in initial concentrations of epoxide, NaCN and HHDH were conducted with aim of model validation. Enzyme deactivation influenced by the initial epoxide concentration was observed within incubation experiments. Operational stability decay was mathematically described and included in the model. Furthermore, with the increase in the epoxide concentration, enzyme stability decreased, while the cyanide nucleophile did not have a significant effect on the stability of the enzyme. Experimental data has shown a satisfactory match with an earlier developed mathematical model. Moreover, mathematical modeling has shown that synthesis in batch/repetitive batch reactor is the optimal pathway for production of this compound
Modeliranje fotokatalitičke razgradnje farmaceutika u vodi višestranim pristupom
No full textPharmaceuticals, as one of the largest groups of contaminants of emerging concern (CECs), pose a threat to the environment and human health. Advanced Oxidation Processes (AOPs) have proven to be effective in the degradation of persistent, toxic, and non-biodegradable pollutants in water. Heterogeneous photocatalytic processes are multiparameter systems pertaining to AOPs based on in-situ generated radical, with overall effectiveness influenced by the different process parameters. Predicting the behaviour of photocatalytic AOPs by means of mathematical simulations is crucial not only for scale-up and process optimization, but also for controlling undesirable environmental effects such as the formation of by products with a higher toxicity than the parent compound. In this work, a multi-faceted approach was applied to develop a simulation model for the photocatalytic process for the degradation and mineralisation of pharmaceutical ibuprofen by UV-A/TiO2 P25. The mathematical – mechanistic model of heterogeneous photocatalysis includes a set of differential equations and takes into account the configuration of the photocatalytic reactor, the irradiation emission, the scattering of irradiation, the process parameters, the reaction kinetics and the degradation mechanism. The developed model was verified by experimental results obtained at different photocatalyst loadings. Coumarin and 1,4-benzoquinone were used as chemical probes to confirm the generation of hydroxyl and superoxide radicals and to fine-tune the chemical reactions in the model. To increase the robustness of the developed model, a variety of organic compounds whose structural features influence important mechanisms in photocatalytic treatment, such as adsorption on the TiO2 P25 surface and the prevalence of degradation by hydroxyl and superoxide radicals, were investigated using quantitative-structure activity/property relationship (QSA/PR) modelling. Adsorption was first investigated by a combined experimental/statistical approach using response surface method (RSM), which yielded a quadratic polynomial equation (QPE) describing adsorption for each organic compound studied. The coefficients of the QPE were related to structural features employing QSA/PR. The degradation of organic compounds by the UV-A/TiO2 P25 process in the presence of coumarin and 1,4-benzoquinone was studied, common radical scavengers for hydroxyl and superoxide radicals were investigated and coefficients were determined based on the kinetics obtained, that diversified the prevalence of oxidation or reduction mechanisms in the degradation of organic compounds. The determined coefficients were correlated with structural features of the investigated organic compounds by QSA/PR modelling. The simulation model developed by the proposed multi-faceted approach achieved good agreement between the predicted and experimental data. The QSA/PR modelling combined with RSM methodology accurately predicted the adsorption of organic compounds with complex molecular structure. The QSA/PR technique also successfully captured relevant structural features that determine degradation kinetics, so it can be used to increase the robustness of mathematical – mechanistic models which ensures their simulation capability for a wide range of organic structures.Farmaceutici, kao jedna od najvećih skupina onečišćivala koji izazivaju zabrinutost (eng. contaminants of emerging concern, CECs), predstavljaju prijetnju za okoliš i ljudsko zdravlje. Napredni oksidacijski procesi (eng. advanced oxidation processes, AOPs) su se pokazali učinkovitim u razgradnji postojanih, toksičnih i biološki nerazgradivih onečišćenja u vodi. Heterogeni fotokatalitički procesi kao dio AOP-a su višeparametarski sustavi, koji se temelje na in-situ generiranju radikala, pri čemu na ukupnu učinkovitost utječu različiti parametri procesa. Predviđanje ponašanja fotokatalitičkih AOP-a primjenom matematičkih simulacija važno je ne samo za uvećanje i optimizaciju procesa, nego i za kontrolu nepoželjnih učinaka na okoliš kao što su stvaranje toksičnijih nusprodukata u odnosu na primarni spoj. U ovom radu primijenjen je višestrani pristup za razvoj simulacijskog modela fotokatalitičke razgradnje i mineralizacije farmaceutika ibuprofena UV-A/TiO2 P25 procesom. Razvijeni matematičko – mehanistički model za heterogenu fotokatalizu sastoji se od seta diferencijalnih jednadžbi koje uključuju konfiguraciju fotokatalitičkog reaktora, emisiju zračenja, raspršenje zračenja, parametre procesa, kinetiku reakcije te mehanizam razgradnje. Razvijeni model verificiran je eksperimentalnim rezultatima dobivenih pri različitim koncentracijama fotokatalizatora. Kumarin i 1,4-benzokinon primijenjeni su u svrhu potvrde generiranja hidroksilnih i superoksidnih radikala te za fino podešavanja kemijskih reakcija na koje utječu u razvijenom modelu. Kako bi se povećala robusnost razvijenog modela istraženi su utjecaji strukturnih značajki različitih organskih spojeva na važne mehanizme fotokatalitičkog procesa, ponajprije na adsorpciju onečišćivala na površini TiO2 P25 te relativni doprinos razgradnji hidroksilnim i superoksidnim radikalima, primjenom kvantitativnog odnosa aktivnosti/svojstava strukture (eng. quantitative structure activity/property, QSA/PR) modeliranja. Adsorpcija je ispitana objedinjenim eksperimentalno/statističkim pristupom korištenjem metode odzivnih površina (eng. response surface methodology, RSM), a rezultat su kvadratne polinomne jednadžbe (eng. quadratic polynomial equation, QPE) koje opisuju adsorpciju za svaki pojedini ispitivani organski spoj. Koeficijenti iz QPE jednadžbi korelirani su sa strukturnim značajkama organskih spojeva primjenom QSA/PR modeliranja. Razgradnjom odabranih organskih spojeva UV-A/TiO2 P25 procesom u prisutnosti kumarina i 1,4-benzokinona, hvatača hidroksilnih i superoksidnih radikala, dobiveni su kinetički modeli te su određeni koeficijenti iz kojih je razvidan doprinos oksidacijskih i redukcijskih mehanizama prilikom razgradnje organskih spojeva. Dobiveni koeficijenti su zatim uspješno korelirani sa strukturnim značajkama ispitivanih organskih spojeva primjenom QSA/PR modeliranja. Simulacijski model, razvijen predloženim višestranim pristupom, ukazuje na dobro slaganje predviđenih i eksperimentalnih podataka. QSA/PR modeliranje kombinirano s RSM metodologijom točno predviđa adsorpciju organskih spojeva složenih molekulskih struktura. QSA/PR metodologija je uspješno ukazala na relevantne strukturne značajke koje određuju kinetiku razgradnje te se može primijeniti za uvećanje robusnosti matematičko – mehanističkog modela, što osigurava sposobnost simulacije modela za širok raspon organskih spojeva
Thermoplastic starch blends as as packaging material
No full textNeodgovarajuće zbrinjavanje plastike nakon korištenja dovodi do povećanja zabrinutosti uslijed rasta globalnih ekoloških problema poput povećanja emisije CO2, smanjenja naftnih izvora i onečišćenja okoliša što rezultira potrebom za istraživanjem i razvojem biorazgradljivih materijala kao alternative konvencionalnim materijalima za pakiranje. Konstantno iscrpljivanje prirodnih resursa uzrokovano materijalima na bazi nafte dovodi do pojave novih biopolimernih materijala primjenjivih kao materijal za pakiranje. Biorazgradljivi materijali razgrađuju se u okolišu pod utjecajem mikroorganizama, vode, kisika i sunčeve svjetlosti, kompostabilni su i proizvode se od obnovljivih izvora energije. Osim pozitivnog utjecaja na okoliš, biorazgradljivi materijali povoljni su za korištenje i s ekonomskog aspekta jer su jeftini, lako dostupni te smanjuju ovisnost tržišne cijene plastike o naftnoj industriji. U ovom radu analizirana su primjenska svojstva pripremljenih biorazgradljivih polimernih mješavina termoplastičnog škroba (TPS) i polilaktida (PLA) bez i s dodatkom limunske kiseline (LK). Cjelokupna identifikacija i karakterizacija biorazgradljivih TPS/PLA mješavina provedena je FTIR - ATR spektroskopijom, morfologija polimernih mješavina pratila se primjenom pretražne elektronske mikroskopije (SEM), toplinska svojstva tehnikama diferencijalne pretražne kalorimetrije (DSC) i termogravimetrijske analize (TGA), a ispitana su i propusnost vodene pare (PVP) te mehanička svojstva pripremljenih polimernih mješavina. Rezultati ukazuju na poboljšanje adhezije između faza TPS-a i PLA dodatkom limunske kiseline, bolju homogenost u strukturi i snažniju kompatibilnost polimernih mješavina što rezultira boljim toplinskim, mehaničkim i barijernim svojstvima analiziranih biorazgradljivih polimernih TPS/PLA mješavina.Improper disposal of plastics after use leads to increasing concerns due to the growth of global environmental problems such as increasing CO2 emissions, decreasing oil sources and environmental pollution resulting in the need for research and development of biodegradable materials as an alternative to conventional packaging materials. The constant depletion of natural resources caused by petroleum-based materials leads to the emergence of new biopolymer materials applicable as packaging materials. Biodegradable materials break down in the environment under the influence of microorganisms, water, oxygen and sunlight, are compostable and are produced from renewable energy sources. In addition to the positive impact on the environment, biodegradable materials are also favorable for use from an economic point of view because they are cheap, easily available and reduce the dependence of the market price of plastic on the oil industry. In this work, the application properties of the prepared biodegradable polymer mixtures of thermoplastic starch (TPS) and polylactide (PLA) without and with the addition of citric acid (LK) were analyzed. The overall identification and characterization of biodegradable TPS/PLA mixtures was carried out by FTIR - ATR spectroscopy, the morphology of polymer mixtures was monitored using scanning electron microscopy (SEM), thermal properties using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques, and permeability was also tested water vapor (PVP) and mechanical properties of prepared polymer mixtures. The results indicate an improvement in the adhesion between TPS and PLA phases with the addition of citric acid, better homogeneity in the structure and stronger compatibility of the polymer mixtures, which results in better thermal, mechanical and barrier properties of the analyzed biodegradable polymer TPS/PLA mixtures
Matematičko modeliranje i optimizacija biokatalitičke sinteze fluoriranih kiralnih građevnih blokova
No full textBiocatalysis is an emerging and important scientific filed for the asymmetric synthesis of pharmaceuticals and fine chemicals that has accomplished astonishing growth in industrial sector in recent years. For individual biocatalytic synthesis to reach its full potential, the process must be explored from the aspect of various scientific fields, including protein engineering, organic chemistry, reaction engineering, and more. The focus of this PhD thesis are halohydrin dehalogenases (HHDHs), promising and yet quite unexplored group of enzymes, and their potential for industrial-scale synthesis. Through extensive research of the existing literature, a serious lack of kinetic data in biotransformations with enzymes from HHDH group was determined. Therefore, one of the objectives of the thesis was to gain insight into kinetic characteristics of HHDH from Agrobacterium radiobacter AD1 (HheC) and develop a mathematical model in synthesis of important building blocks, since this approach may lead to the discovery of enzyme kinetic limitations and process bottlenecks, and, more importantly, enable the enhancement of process outcome through model-based simulations. The investigated reactions were kinetic resolutions for the synthesis of optically pure, fluorinated β-substituted alcohols and epoxides that represent valuable building blocks in pharmaceutical and fine chemicals industries. Ring-opening reactions of fluorinated styrene oxide derivatives, catalyzed by wild-type HheC and its variants W249P and ISM-4, were explored. Fluorinated derivatives of styrene oxide with substituents in para-position were found to be most convenient substrates for HheC based on the activity, enantioselectivity and hydrolytic stability, whereby 2-[4-(trifluoromethyl)phenyl]oxirane stood out as the best option. Enzyme variant W249P, with exchanged Trp and Pro amino acids on position 249, displayed higher substrate affinity in comparison to the wild type. Hence, it was selected for further kinetic investigation. The synthesis of (R)-2-azido-1-[4-(trifluoromethyl)phenyl]ethanol was described by double substrate Michaelis-Menten kinetics, with the presence of enzyme inhibitions with reacting substrate (R)-2-[4-(trifluoromethyl)phenyl]oxirane,
opposite enantiomer (S)-2-[4-(trifluoromethyl)phenyl]oxirane,
product (R)-2-azido-1-[4-(trifluoromethyl)phenyl]ethanol,
by-product rac-2-[4-(trifluoromethyl)phenyl]-1,2-ethanediol, and co-solvent DMSO.
Apart from numerous inhibitions and substantial hydrolysis effect, operational stability decay was found to contribute greatly to the synthesis outcome on higher concentration scale, since deactivation constant is directly correlated to the initial concentration of the substrate, 2-[4-(trifluoromethyl)phenyl]oxirane. The mathematical model was developed, and process simulations were employed in process optimization. Significant improvements in process metrics were achieved by modifying reactor set-up and selecting suitable initial conditions. The optimized biocatalytic system in repetitive batch reactor led to high reaction yield and optical purity (Y = 95%, ee > 99 %). However, process should be optimized further in order to increase reaction productivity that meets the target for industrial synthesis. The existence of various enzyme inhibitions and concentration-dependent enzyme deactivation, as well as low solubility and hydrolytic instability of the substrate, makes the system convenient for the switch from aqueous to alternative media. In the second part of the thesis, the focus was on the investigation of the influences of organic solvents (OSs) on HheC catalytic and structural performances. The stability of HheC in presence of dimethyl sulfoxide (DMSO), the most used co-solvent in HHDH-catalyzed biotransformations, was found to be preserved in cases when DMSO volume ratio does not exceed 30% (v/v). In higher DMSO content, HheC is not able to retain native structure and is completely and rapidly inactivated at 50% (v/v)
co-solvent. This was confirmed by the combination of experimental studies, including monitoring enzyme stability and protein size distributions during incubation with different DMSO content, together with molecular dynamic studies (MD). DMSO also proved to be a mixed-type inhibitor of HheC in the reactions of para-nitro-2-bromo-1-phenylethanol (PNSHH) dehalogenation and para-nitro styrene oxide (PNSO) ring-opening with bromide ions. The inhibitory behavior was detected by kinetic Lineweaver-Burk analysis and confirmed by MD. Likewise, DMSO was found to be inhibitor of W249P variant in
(R)-2-[4-(trifluoromethyl)phenyl]oxirane azidolysis during kinetic investigation. Wild-type HheC also displayed inadequate catalytic properties in presence of other tested
water-miscible co-solvents, specifically dimethylformamide, methanol, isopropanol, acetonitrile, and tetrahydrofuran. In case of hydrophobic solvents, a direct correlation between HheC activity and logP value was found in PNSHH ring-closure reaction. Knowledge of such a relationship makes biocatalysis with organic solvents more predictable, which may reduce the need to experiment with a variety of solvents in the future. However, this trend was not reported for PNSO ring-opening reaction. From hydrophobic OSs, tested alkanes (cyclohexane, n-hexane, n-heptane) were found to be compatible with HheC activity and stability during incubation, indicating the preservation of high enzyme structural integrity in these biphasic systems. Chloroform and toluene displayed inhibitory properties, especially in ring-opening reaction, which is more valuable from the synthetic point of view. In comparison to the wild type HheC, thermostable variant ISM-4 performed better in presence of OSs in terms of activity, stability, and enantioselectivity. In other words, the link between thermal stability and resistance to the action of OSs was established. These results revealed that ISM-4 has excellent potential for biotransformations in organic media, and as such should be explored for future implementations.Biokataliza je važno znanstveno područje u razvoju za asimetričnu sintezu lijekova i finih kemikalija koje je postiglo zapanjujući rast u industrijskom sektoru posljednjih godina. Kako bi pojedinačna biokatalitička sinteza dosegla svoj puni potencijal, proces se mora istražiti s aspekta različitih znanstvenih područja, uključujući proteinsko inženjerstvo, organsku kemiju, reakcijsko inženjerstvo itd. U fokusu ovog doktorskog rada su halogenhidrin-dehalogenaze (HHDH), obećavajuća ali još nedovoljno istražena skupina enzima, te njihov potencijal za industrijsku sintezu. Opsežnim istraživanjem postojeće literature utvrđen je ozbiljan nedostatak kinetičkih podataka u biotransformacijama s enzimima iz skupine HHDH. Stoga je jedan od ciljeva doktorskog rada bio dobiti uvid u kinetičke karakteristike HHDH iz Agrobacterium radiobacter AD1 (HheC) i razviti matematički model za sintezu važnih građevnih blokova, budući da ovaj pristup može dovesti do otkrića kinetičkih ograničenja enzima i uskih grla procesa te, što je još važnije, omogućiti poboljšanje ishoda procesa kroz simulacije temeljene na modelu. Istraživane reakcije bile su kinetičke rezolucije za sintezu optički čistih, fluoriranih β-supstituiranih alkohola i epoksida koji predstavljaju vrijedne gradivne elemente u farmaceutskoj industriji i industriji finih kemikalija. Istražene su reakcije otvaranja prstena fluoriranih derivata stiren-oksida, katalizirane divljim tipom HheC i njegovim mutantima W249P i ISM-4. Utvrđeno je da su fluorirani derivati stiren-oksida sa supstituentima u parapoložaju najprikladniji supstrati za HheC na temelju aktivnosti, enantioselektivnosti i hidrolitičke stabilnosti, pri čemu se 2-[4-(trifluormetil)fenil]oksiran istaknuo kao najbolja opcija. Enzim W249P, sa zamijenjenim Trp i Pro aminokiselinama na poziciji 249, pokazao je veći afinitet prema supstratu u usporedbi s divljim tipom, stoga je odabran za daljnje kinetičko istraživanje. Sinteza (R)-2-azido-1-[4-(trifluorometil)fenil]etanola opisana je dvosupstratnom Michaelis-Menteničinom kinetikom, uz prisutnost inhibicija enzima sa supstratom (R)-2-[4-(trifluormetil)fenil]oksiranom,
suprotnim enantiomerom (S)-2-[4-(trifluormetil)fenil]oksiranom,
produktom (R)-2-azido-1-[4-(trifluormetil)fenil]etanolom,
nusproduktom rac-2-[4-(trifluorometil)fenil]-1,2-etandiolom, i ko-otapalom DMSO.
Osim brojnih inhibicija i značajnog učinka hidrolize, utvrđeno je da pad operacijske stabilnosti enzima uvelike pridonosi ishodu sinteze pri višim koncentracijama, budući da je konstanta deaktivacije enzima izravno ovisna o početnoj koncentraciji supstrata, 2-[4-(trifluorometil)fenil]oksirana. Razvijen je matematički model, a pri optimizaciji procesa korištene su simulacije procesa. Značajna poboljšanja u ishodu sinteze postignuta su modificiranjem tipa reaktora i odabirom odgovarajućih početnih uvjeta. Optimizirani biokatalitički sustav u repetitivnom šaržnom reaktoru doveo je do visokog iskorištenja na produktu i optičke čistoće (Y = 95%, ee > 99 %). Međutim, proces treba dodatno optimizirati kako bi se povećala produktivnost reakcije koja ispunjava ciljeve za industrijsku sintezu. Postojanje različitih inhibicija i deaktivacije enzima ovisne o koncentraciji, kao i niska topljivost i hidrolitička nestabilnost supstrata, čine sustav pogodnim za prelazak s vodenog na alternativni medij. U drugom dijelu doktorskog rada fokus je bio na istraživanju utjecaja organskih otapala (engl. organic solvent – OS) na katalitička i strukturna svojstva HheC. Utvrđeno je da je stabilnost HheC u prisutnosti dimetil-sulfoksida (DMSO), najčešće korištenog ko-otapala u HHDH-biotransformacijama, očuvana u slučajevima kada volumni udio DMSO ne prelazi 30% (v/v). Pri većem udjelu DMSO, HheC nije u stanju zadržati prirodnu strukturu te se potpuno i brzo inaktivira pri 50% (v/v) ko-otapala. To je potvrđeno kombinacijom eksperimentalnih istraživanja, uključujući praćenje stabilnosti enzima i raspodjele veličine proteina tijekom inkubacije s različitim sadržajem DMSO, zajedno s molekulsko-dinamičkim studijama (engl. molecular dynamics – MD). Prema HheC, DMSO se također pokazao kao inhibitor miješanog tipa u reakcijama dehalogenacije para-nitro-2-bromo-1-feniletanola (PNSHH) i otvaranja prstena para-nitro stiren oksida (PNSO) s bromidnim ionima. Inhibicijsko ponašanje otkriveno je kinetičkom Lineweaver-Burk analizom i potvrđeno MD analizom. Isto tako, tijekom kinetičkih ispitivanja, otkriveno je da je DMSO inhibitor W249P mutanta tijekom azidolize (R)-2-[4-(trifluorometil)fenil]oksirana. Divlji tip HheC također je pokazao neadekvatna katalitička svojstva u prisutnosti drugih testiranih ko-otapala koja se miješaju s vodom, a posebice dimetilformamida, metanola, izopropanola, acetonitrila i tetrahidrofurana. U slučaju hidrofobnih otapala, izravna korelacija između aktivnosti HheC enzima i logP vrijednosti pronađena je u reakciji zatvaranja prstena PNSHH. Saznanje o takvoj ovisnosti čini biokatalizu s organskim otapalima predvidljivijom, što može smanjiti potrebu za eksperimentiranjem s različitim otapalima u budućnosti. Međutim, ovaj trend nije pronađen u reakciji otvaranja PNSO prstena. Od hidrofobnih OS, utvrđeno je da su alkani (cikloheksan, nheksan, n-heptan) kompatibilni s HheC aktivnošću i stabilnošću tijekom inkubacije, što ukazuje na očuvanje visokog strukturnog integriteta enzima u ovim dvofaznim sustavima. Kloroform i toluen pokazali su inhibicijska svojstva, posebno u reakciji otvaranja prstena koja je vrjednija sa sintetičkog gledišta. U usporedbi s divljim tipom HheC, termostabilni mutant ISM-4 demonstrirao je bolje rezultate u prisutnosti OS u smislu aktivnosti, stabilnosti i enantioselektivnosti. Drugim riječima, za slučaj ovog enzima utvrđena je poveznica između termičke stabilnosti i otpornosti na djelovanje otapala. Ova istraživanja otkrila su da ISM-4 mutant enzima ima izvrstan potencijal za biotransformacije u organskim medijima, te bi ga kao takvog trebalo istražiti za buduće primjene
Synthesis of mesoporous silica
No full textTijekom 20. i početkom 21. stoljeća došlo je do značajnog razvoja znanosti u području nanotehnologije i istraživanja nanostrukturiranih materijala, uključujući mezoporozne materijale i mezoporoznu siliku. Mezoporozni materijali posjeduju poroznu strukturu i veliku specifičnu površinu koja im omogućuje široku primjenu u raznim područjima znanosti i tehnologije. Klasificiraju se prema veličini i strukturi pora. Mezoporozne SiO2 čestice različitih struktura i morfologije, a time i različitih svojstava moguće je pripremiti promjenom uvjeta sinteze. Mezoporozni materijali predstavljaju važan materijal s velikim potencijalom za primjenu u različitim područjima znanosti i tehnologije, što ovo područje čini zanimljivim za daljnja istraživanja. Ključna primjena mezoporozne silike je imobilizacija enzima koja omogućava vezanje na stabilan nosač. Imobilizirani enzimi imaju široku primjenu u industrijskim i biotehnološkim procesima, a katalitička aktivnost ostaje im očuvana te omogućuje neprestanu i višekratnu upotrebu. Cilj ovog rada bio je sintetizirati i karakterizirati čestice mezoporozne silike s različitim veličinama pora, mijenjajući omjer komponenata koje sudjeluju u stvaranju mezoporozne strukture.During the 20th and early 21st century, there have been significant scientific development in the field of nanotechnology and the research on nanostructured materials, including mesoporous materials and mesoporous silica. Mesoporous materials have a porous structure and a high specific surface area that enables their wide application in various fields of science and technology. They are classified based on their pore size and structure. Mesoporous SiO2 particles of various structures, morphologies and thus properties, can be prepared by altering synthesis conditions. Mesoporous materials represent an important material with significant potential for application in various fields of science and technology, rendering this field interesting for further research. The important application of mesoporous silica is in enzyme immobilization where is used as carrier. Immobilized enzymes are widely used in industrial and biotechnological processes, because they retain their catalytic activity and can be used continuously and repeatedly. The aim of this study was to synthesize and characterize mesoporous silica particles with different pore sizes by adjusting the ratio of components involved in the formation of the mesoporous structure
Removal of the phenol from wastewaters
No full textFenol, jedan od najčešćih organskih onečišćivala vode, vrlo je otrovan čak i u niskim koncentracijama. Često se koristi u raznim industrijskim procesima kao što su proizvodnja ljepila, petrokemijska industrija, građevinarstvo i automobilska industrija te na taj način i dospijeva u otpadne vode koje se iz tih industrijskih postrojenja ispuštaju. Prije ispuštanja u okoliš, fenol je potrebno ukloniti iz otpadnih voda. Napredni oksidacijski procesi (AOP) nametnuli su se kao vrlo učinkovito rješenje uklanjanja fenola iz otpadnih voda. U ovim procesima, uz utrošak energije, nastaju reaktivni radikali koji reagiraju sa organskim spojem te u konačnici nastaju voda i ugljikov dioksid. Zadatak ovog rada je provesti obradu modelne vode onečišćene fenolom te odrediti kako procesni parametri utječu na učinkovitost uklanjanja fenola. Korištena je napredna oksidacijska tehnika uz UVC zračenje te vodikov peroksid (H2O2) i natrijev persulfat (Na2S2O8) kao oksidacijska sredstva. Izrađen je puni faktorski plan eksperimenta na tri razine. Procesni parametri čiji je utjecaj promatran su pH (od 4 do 10) i koncentracija oksidansa (od 10 do 200 mM). Rezultati ovog rada pokazali su da na razgradnju fenola metodom UV/H2O2 utječe pH vrijednost dok koncentracija oksidansa ne utječe. Na razgradnju fenola metodom UV/S2O8 utječe koncentracija okisidansa, a pH vrijednost nema utjecaja. Provedena je i izravna fotoliza fenola UVC zračenjem te su rezultati pokazali da niže pH vrijednosti pogoduju razgradnji fenola u ovim uvjetima.Phenol, one of the most common organic water pollutants, is highly toxic even in low concentrations. Phenol is often used in various industrial processes such as production of adhesives, petrochemical industry, construction and automotive industry. Result is that phenol ends up in the wastewater from these industries. Before releasing into the environment, phenol must be removed from wastewater. Advanced oxidation processes have emerged as a very effective solution for removing phenol from wastewater. In these processes, with the consumption of energy, reactive radicals are formed and they react with organic compound and produce water and carbon dioxide. The purpose of this work was to perform the treatment of water contamined with phenol and to investigate the influence of process parameters on the efficiency of the treatment. An advanced oxidation technique was used with UVC radiation and hydrogen peroxide or sodium persulfate as an oxidizing agent. For this purpose, a full factorial design of the experiment was created at three levels. The influence of process parameters, pH (from 4 to 10) and oxidant concentration (from 10 to 200 mM) was observed. The results of this work revealed that the pH is significant while the concentration of oxidant is not significant for UV/H2O2, while the concentration of oxidants is significant and the pH is not significant for UV/S2O8 technique. Direct photolysis of phenol by UVC radiation was also performed and the results revealed that lower pH favor the decomposition of phenol under these conditions
Thermal properties and kinetics of thermal decomposition of multiple recycled polypropylene
No full textU radu je provedeno istraživanje utjecaja višestrukog recikliranja na degradaciju polipropilena (PP) budući da se široko primjenjuje zbog svojih dobrih svojstava te posljedično nastaju velike količine otpada, a potom i mikroplastike (MP) u okolišu. Reciklat PP dobiven je od tvrtke Poliplast d.d., koji je potom mehanički recikliran u četiri ciklusa, ekstrudiranjem, pri temperaturi od 200 °C. Uzorci su karakterizirani nakon svakog ciklusa recikliranja, kako bi se utvrdio stupanj degradacije i promjena svojstva PP. Karakterizacija je provedena: difuznom refleksnom spektroskopijom (DRS), određivanjem brzine protjecanja taljevine (MFR) te termogravimetrijskom analizom (TGA) iz koje je određena kinetika toplinske razgradnje primjenom Flynn-Wall-Ozawa (FWO) modela. Analiza rezultata dobivenih DRS, MFR i TGA tehnikama pokazuje da prilikom recikliranja uzoraka na povišenim temperaturama dolazi do blage razgradnje polipropilena.This paper investigates the impact of multiple recycling on the degradation of polypropylene (PP), since it is widely used due to its good properties, and as a result, large amounts of waste and then microplastics (MP) are generated in the environment. Recycled PP was obtained from the company Poliplast d.d., which was then mechanically recycled in four cycles, by extrusion, at a temperature of 200 °C. The samples were characterized after each recycling cycle, in order to determine the degree of degradation and change in PP properties. Characterization was performed by: diffuse reflection spectroscopy (DRS), determination of melt flow rate (MFR) and thermogravimetric analysis (TGA), from which the kinetics of thermal decomposition were determined using the Flynn-Wall-Ozawa (FWO) model. The analysis of the results obtained by DRS, MFR and TGA techniques shows that when samples are recycled at elevated temperatures, a slight degradation of polypropylene occurs
Synthesis and biological activity of thienobenzo-triazoles
No full textCilj rada bio je sintetizirati nove tienobenzo-triazole te ispitati njihovu inhibicijsku potenciju prema kolinesterazama. Također je procijenjena selektivnost njihove inhibicije, a rezultati su interpretirani molekularnim modeliranjem. Uspješno je sintetizirano 15 novih spojeva koji se razlikuju po supstituentu pričvršćenom na triazolni prsten ili po aromatičnosti središnjeg prstena. Fotociklizacijskim putem sintetiziran je jedan spoj 1, dok je alternativni put dao širok spektar molekula dihidro-tienobenzo-triazola i aromatiziranih tienobenzo-triazola 2-15.
Većina novih molekula pokazala je bolju inhibicijsku potenciju prema butirilkolinesterazi
(BChE – eng. butyrylcholinesterase). Računalne studije ukazuju na povezivanje
tienobenzo-triazola s kolinesterazama preko vodikovih veza koje uključuju jedan od dušika triazola, smještenih između aromatskih ostataka liganda i aromatskih ostataka aktivnih mjesta kolinesteraza. Također su prisutne i alkilne interakcije. Molekularno pristajanje omogućuje uvid u strukturu dobivenih kompleksa i identifikaciju stabilizirajućih interakcija između enzima i potencijalnog inhibitora kolinesteraze. Novosintetizirani tienobenzo-triazoli pokazali su dobre karakteristike za budući dizajn inhibitora kolinesteraza i traženje terapeutika za liječenje neuroloških poremećaja.The aim of this study was to synthesize new thienobenzo-triazoles and to examine their inhibitory potency towards cholinesterases. The selectivity of their inhibition was also assessed, and the results were interpreted by molecular modeling. 15 new compounds have been successfully synthesized, differing in the substituent attached to the triazole ring or by the aromaticity of the central ring. A single compound 1 was synthesized by photocyclization route, while the alternative pathway gave a wide range of molecules of
dihydro-thienobenzo-triazole and aromatized thienobenzo-triazole 2-15. Most of the new molecules showed better inhibitory potency towards butyrylcholinesterase (BChE). Computational studies suggest that thienobenzo-triazole and cholinesterases are linked via hydrogen bonds involving one of the triazole nitrogen, located between aromatic ligand residues and aromatic residues of the active cholinesterase sited. Alkyl interactions are also present. Molecular docking gives insight into the structure of the obtained complexes and the identification of stabilizing interactions between enzymes and a potential cholinesterase inhibitor. The newly synthesized thienobenzo-triazoles showed good characteristics for the future design of cholinesterase inhibitors and the search for therapeutics for the treatment of neurological disorders
Removal of cyanide and thiocyanate from wastewater
No full textCijanidi i tiocijanati su anorganske tvari koje su dugo poznate i nalaze se u okolišu svakodnevno u manjim koncentracijama. Razvojem i sve većeg djelovanja industrije došlo je do znatnog porasta koncentracije tih tvari. Glavni izvor otpadnih voda koje ih sadrže su industrije prerade metala i kompleksnih spojeva. Cijanidi i tiocijanati su tvari koje su vrlo nestabilne i reaktivne te mogu reagirati s organskim tvarima i tvoriti vrlo toksične spojeve. Zbog tih karakteristika, toksičnost spojeva je dodatno izražena, što također negativno utječe na ljudski, životinjski i biljni svijet. Razvojem kemije, poznavanje ovih tvari je znatno napredovalo zajedno sa poznavanjem njihovih karakteristika, što omogućuje izume novih metoda za njihovo uklanjanje. Cilj ovog rada je istražiti i opisati neke od metoda koje se koriste u svrhu uklanjanja cijanida i tiocijanata iz otpadnih voda. Cilj je postići razumijevanje ovih metoda i njihovu primjenu kako te tvari ne bi dospjele u kontakt sa živim svijetom i prouzročilo nepovratne negativne posljedice.Cyanides and thiocyanates are anorganic substances, which are known for a long time and are daily spread in nature in smaller concentrations. With the development and rise in it's activity of industry, their concentrations have grown in all kinds of compounds of these substances. Main sources of wastewaters that contain them are industries of metal and compley compounds. Cyanides and thiocyanates are very unstable and reactive and can react with organic compounds to create very toxic compounds. Because of these characteristics, their toxycity is enhanced, which can have an negative affect on human, animal and plant life. With the development of chemistry, their understanding significantly advanced together with the understanding of their characteristics, which allowed the development of new methods for their removal. The goal of this thesis is to explore and describe some of the methods, which are to be used for the extraction of cyanides and thiocyanates from wastewaters. The goal is to develope better understanding and their uses, so the substances wouldn't come in contact with the living world and cause irreversible negative effects