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Coumarins and triazoles are two interesting groups of heterocyclic compounds, both exhibiting a wide range of biological activities. The joining of these two scaffolds into a hybrid compound with the improved activities has already been reported. [1] In this research, 11 new hybrid compounds were synthesized, utilizing a deep eutectic solvent as an environmentally sustainable method of organic synthesis. Compounds were obtained in good yields through a one-step reaction of coumarinyl hydrazides and various substituted isothiocyanates, without the use of catalysts. [2] Since many commercially available fungicides are based on triazole derivatives, antifungal activity of 1, 2, 4-triazolyl coumarins was evaluated in vitro on two pathogenic fungi, Fusarium oxysporum and Fusarium culmorum. The tested compounds moderately inhibited the mycelial growth of F. oxysporum (35.0-57.5%), but were mostly ineffective against F. culmorum. Compound 1b, as the most potent growth inhibitor, was further analyzed computationally. A molecular docking analysis was performed to evaluate the binding mode of compound 1b with sterol 14 α-demethylase, the target enzyme of triazole based fungicides

The substantial increase in pest’s resistance to commonly used pesticides as well as the concern of growing environmental pollution have been the biggest challenges agricultural industry had to face in recent years. Large efforts have been made to produce a variety of novel and environmentally sustainable compounds to be used as an alternative to commercially available pesticides. [1] A set of 36 newly synthesized triazole derivatives have been assayed as potential acetylcholinesterase inhibitors by utilizing the Ellman’s protocol. [2] The highest inhibition percentages were obtained with compounds 7h (68.32%), KM35 (49.77%), KM16 (48.04%), KM18 (47.82%), and KM19 (39.89%). In vivo study was performed on two species of nematodes ; Heterorhabditis bacteriophora and Steinernema feltiae. The nematodes were exposed to aforementioned compounds in the period of 72 h. The highest mortality rate of Heterorhabditis bacteriophora species was observed with the compound KM16 with the value of 75.0% after 48 h of incubation, while he highest mortality rate of Steinernema feltiae was observed with the compound KM18 with the value of 50.0% after 48 and 72 h of incubation. The inhibition percentages do not seem to correlate with the in vivo results, as the compound 7h had one of the lowest mortality rates within the tested group of compounds among the both nematode species.

U pozvanom predavanju obrađeni su mehanizmi nastajanja omega-3 nezasićenih masnih kiselina, njihov metabolizam u ljudskom tijelu kao i efekti koje imaju na ljudski organizam.

Prema organizaciji Alzheimer’s Disease International, oko 55 milijuna ljudi na svijetu boluje od Alzheimerove bolesti ili drugih oblika demencije u 2020. godini. Najčešći način liječenja spomenutih stanja je inhibicija acetilkolinesteraze (AChE) i amiloid beta enzima u ljudskom mozgu korištenjem komercijalnih farmaceutika kao što su donepezil i aducanumab [1]. Prethodna istraživanju upućuju da propolis ima značajna inhibicijska svojstva AChE prvenstveno zbog visokog sadržaja fenola koji čine čak 60% ukupnog udjela komponenti u propolisu [2]. Test inhibicije AChE proveden je provođenjem Ellmanove metode [3]. Uzorci propolisa osigurani su od strane obiteljskog poljoprivrednog gospodarstva Boris Buratović sa otoka Hvara. Uz ostale cvjetne vrste, lokalitet sa kojeg je prikupljen propolis obiluje ružmarinom (Salvia rosmarinus), lavandom (Lavandula angustifolia) i vrijesom (Calluna vulgaris), biljkama koje mogu značajno utjecati na sadržaj fenola u usporedbi s propolisom prikupljenim u kontinentalnim krajevima. Volumni postotci propolisa u reakcijskoj smjesi iznosili su 5%, 3, 5% i 2, 5%. Najviši postotak inhibicije od 67, 14% postignut je s volumnim postotkom propolisa od 5%.

In silico methods are used for a rational approach in screening, optimization, and the design of newly synthesized compounds as potential agents in plant protection. The tested compounds are quinazolinone-based Schiff bases synthesized by the means of the green chemistry procedures, such as microwave-assisted, ultrasound-assisted, and mechanochemical synthesis. The aim of the study is to evaluate the inhibitory activity of mentioned compounds on enzymes that have a crucial role in the growth and spreading of plant pathogenic fungi, such as Macrophomina phaseolina, Sclerotinia sclerotiorum, Fusarium oxysporum f. sp. Lycopersici and F. culmorum. In silico study was performed by the use of molecular docking on enzymes responsible for the fungal growth: demethylase ((CYP51), pdb ID: 5eah), chitinase (pdb ID: 4txe), transferase (Nmyristoyltransferase, pdb ID: 2p6g), as well as enzymes responsible for the degradation of the plant cell-wall: endoglucanase I (pdb ID: 4ovw), proteinase K (pdb ID: 2pwb), pectinase (endopolygalacturonase, pdb ID: 1czf). The binding affinity and interactions with the active sites of enzymes was determined the mode of action of the most active compounds against fungi.

Plant diseases and pests are responsible for many losses in agricultural production worldwide, proving that their control is crucial for crop farming today. The use of plant protection products has effectively limited these losses. However, some of the active ingredients of these products are toxic for humans and fauna or cause groundwater and soil pollution. Therefore, there is an urgent need to find new, environmentally and toxicologically acceptable active ingredients for plant protection. In this study, we have tested the antifungal activity of 19 quinazolinone based Schiff bases against Sclerotinia sclerotiorum (Lib.) de Bary, a necrotrophic fungal pathogen causing disease in a variety of plants. Most of the tested compounds showed very good fungal growth inhibition at 0.8 μmol/mL, with 8 compounds inhibiting mycelial growth by more than 80 %. QSAR techniques provide an insight into the relationship between structure and biological activity of compounds, presenting an alternative path for the design and development of new active ingredients for plant protection. To elucidate important structural and physicochemical characteristics of tested quinazolinone Schiff bases related to their increased antifungal activity, a QSAR analysis was performed.

Novel derivates of benzothiazoles and benzimidazoles have been evaluated on T-cell lymphoma (HuT78), as well as on normal Madin-Darby canine kidney cells (MDCK-1). Cytotoxic effects of 77 benzothiazoles and benzimidazoles against non-tumour MDCK-1 cells were ranked by activities, and 17 compounds were chosen for the test set. The best QSAR model expressed by multiple linear regression equation was generated by five molecular descriptors calculated by DRAGON program: SIC1, GATS4p, BEHv6, BELp1, and R7m. Williams plot of the applicability domain, detected one molecule as a border outlier and no molecule out of the warning leverage. After removing outlier, the new model has the model achieved better statistical performance of internal and external validation: R2train = 0.74 ; F = 30.76 ; ΔK = 0.08 ; CCCtr = 0.85 ; Q2loo = 0.68 ; CCCcv = 0.81 ; R2Yscr = 0.09 ; Q2Yscr = -0.13 ; R2ext = 0.83 ; CCCext = 0.85 ; Δr2m = 0.25. Molecules without atoms with higher atomic mass as substituents (Cl, F) and more equal neighbor atoms have higher activity. QSAR study for antiproliferative activity on T-cell lymphoma (HuT78) cell was performed on a total of 59 molecules (47 training, 12 test set). The best-obtained model includes three descriptors: MATS8v, Mor09p, Mor30m, and E2u. After exclusion of three outliers from data set, relived by Williams plot (Figure 1) resulted on the predictive model: R2train = 0.87 ; F = 66.48 ; ΔK = 0.12 ; CCCtr = 0.93 ; Q2loo = 0.83 ; CCCcv = 0.91 ; R2Yscr = 0.09 ; Q2Yscr = -0.15 ; R2ext = 0.87 ; CCCext = 0.85 ; Δr2m = 0.13. An increasing number of atomic van der Waals volumes, such as in sulphur atom in benzothiazoles, as molecules without atoms, have higher atomic mass as substituents (Cl, F) enhancing antiproliferative activity on MDCK-1 cells.

Phytopathogenic fungi are one of the leading causes of plant diseases that reduce crop quality and cause huge yield losses. The control of fungal plant diseases is important for reducing or preventing these losses. The excessive use of available fungicides over a long period of time has increased the fungal resistance and become a major ecological issue, giving the incentive to find new antifungal agents. Quinazolinone is a common heterocyclic nitrogen scaffold, widely present in natural products. Its derivatives exert a variety of biological activities, such as antitumor, antiviral, antibacterial and antifungal. The aim of this study was to examine a potential antifungal activity of several structurally different, recently synthesized new quinazolinone derivatives using a computational approach. A molecular docking analysis has been performed on two fungal chitinases, type A (PDB ID: 2XUC) and B (PDB ID: 2IUZ), involved in chitin decomposition, cell wall degradation and remodeling. Molecular docking has shown that all tested compounds bind near the enzyme active sites. The most promissing compounds were N2, N6- bis(2-methyl-4- oxoquinazolin-3(4H)-yl)pyridine-2, 6-dicarboxamide for chitinase A, and 3-(4- methoxyphenyl)-2- methyl-6-nitroquinazolin-4(3H)- one for chitinase B.

Coumarin and its derivatives are well-known phytochemicals that have shown great potential in acetylcholinesterase (AChE) inhibition [1]. Novel coumarin derivatives have been tested as acethylcholinesterase (AChE) inhibitors by utilizing the Ellman's method [2]. Inhibition data were expressed as a logarithm of inhibition percentages. Molecular structures were optimized by PM3 method using Hyperchem software. Molecular descriptors have been calculated by ADMEWORKS ModelBuilder software. QSAR analysis for inhibition of AChE was performed on the 34 compounds in the training set. Due to the small number of compounds, they were not split in training and test sets. The best QSAR model obtained is: log inh.% = - 1.09 – 0.11 MATS7m + 1.84 MCB + 0.17 DIPZ (1) where MATS7m is Moran autocorrelation of lag 7, weighted by atomic masses ; MCB is Balabans topological index, and DIPZ is dipole moment on Z axes. The model has achieved the following statistical performance of the internal validation: R2 = 0.78 ; F = 37.26 ; Δk = 0.23 ; CCCtr = 0.88 ; CCCcv = 0.84 ; Q2loo = 0.71 ; Q2γscr = -0.18. Williams plot for applicability domain of model (1) is shown in Figure 1. Molecular descriptors in model (1) revealed that effect of inhibition of molecules decreased with: lower number of atoms higher mass at spatial lag 7, increasing branching, and small difference in electronegativity between two bonded atoms at the Z axes.

Schiff base derivatives were synthesized by utilizing the green chemistry methods such as microwave-assisted, ultrasound-assisted and mechanochemical synthesis. [1] Acetylcholinesterase inhibitors are widely recognised as potential drugs for treating symptoms of the Alzheimer's disease. Inhibitory properties of AChE inhibitors have been used for the developmet of active compounds in plant protection treatments. Twenty-four Schiff base derivatives were tested as potential acetylcholinesterase inhibitors. In vitro experiment has been conducted on a 96-well microplate UV-Vis reader by utilizing the modified Elmann's method. [2] Absorbance readings were obtained by measuring at the wavelenght of 412 nm. Donepezil was used as a standard acetylcholinesterase inhibitor. The highest percentage of inhibition was obtained with the compound 10 (Fig. 1), 34.58%, while the lowest inhibition percentage was obtained with compound 26 (3.88%).

Sclerotinia sclerotiorum (Lib.) de Bary is a necrotrophic plant pathogen responsible for the reduction of the crop quality and yield. One of the most efficient ways to prevent and control diseases caused by S. sclerotiorum is the use of chemical fungicides. However, their use led to the accumulation of residual fungicides in the soil, water, and agricultural products, as well as the appearance of fungicide-resistant forms of this phytopathogen. Therefore, there is a need for new, environmentally friendly compounds that would prove effective against S. sclerotiorum. This study aimed to derive a Quantitative Structure- Activity Relationship (QSAR) for the antifungal activity of 18 quinazolinone derivatives. Antifungal test against S. sclerotiorum was carried out according to the method of Siber et al. Antifungal activities of tested compounds, expressed as % inhibition, were converted in the form of the logarithm values (log % inhibition). The optimized 3D strictures of quinazolinone derivatives were used for the descriptor calculation. Considering the limited number of compounds, splitting into test and training set was not performed. The multiple linear regression QSAR models were obtained with a genetic algorithm (GA) using QSARINS 2.2.4. (University of Insubria, Varese, Italy). The best QSAR model was generated with three DRAGON descriptors: Mv, Mor09e and R6e. The model satisfied the fitting and internal validation criteria, confirming its stability and robustness: R2 = 0.91 ; R2adj = 0.89 ; F = 45.17 ; ΔK = 0.12 ; CCCtr = 0.95 ; Q2loo = 0.85 ; R2-Q2loo = 0.06 ; CCCcv = 0.92 ; R2Yscr = 0.18 ; Q2Yscr = -0.43. Molecular descriptors in obtained QSAR model revealed that quinazolinones of higher molecular weight (Mv), higher contribution of 3D distribution of electronegativity at 8 Å (Mor09e), and enhanced interactions of electronegative atoms at a topological distance 6 (R6e), have lower antifungal effects.

The use of propolis in human nutrition dates back to ancient times primarily due to its antibacterial and antiviral properties. Chemical analysis of propolis samples revealed over 300 chemical compounds, the most important groups of which are flavonoids, terpenes and phenols. The chemical composition and properties of propolis significantly depend on the geographical and botanical origin, as well as on the type of bees that collect propolis. The research on Brazilian red and green propolis is constantly growing with the aim of discovering new pharmaceutical preparation that show great activity in antiviral processes. This paper presents an overview of available studies of application of propolis active components in the control and prevention of infectious viruses such as HIV, HSV and others.

Human dipeptidyl peptidase III (hDPP III) is a zinc‐hydrolase that cleaves dipeptides sequentially from the N‐ terminal of different bioactive peptides. Although the physiological role of hDPP III is not yet fully elucidated, its involvement in pathophysiological processes such as mammalian pain modulation and blood pressure regulation emphasizes the need to find new hDPP III inhibitors. Coumarins exhibit a variety of biological activities, and Schiff bases bearing coumarin moiety in conjunction with the imino group (-C=N-) form significant compounds in medicinal and pharmaceutical chemistry. To find new potential inhibitors of hDPP III, in this research we selected 6 coumarinyl Schiff bases to investigate their interactions with hDPP III, combining experimental and computational approaches. hDPP III activity was determined using the spectrophotometric assay, while molecular docking was performed by AutoDock Vina software to obtain information regarding the possible interactions of the strongest inhibitor and hDPP III binding site. The experimental results showed that all analyzed compounds have an inhibitory effect against hDPP III activity at the physiological concentration i.e., 100 μM. The strongest inhibition (87.9 %) has been obtained with compound 5. Docking predicts that 5 interacts with amino acid residues of hDPP III mostly in the region of inter-domain cleft by forming hydrogen bonds with Ile386, His568 and Arg572, π – interactions with Phe109, Pro387 and Ala388, and numerous van der Waals interactions. Most of these residues are found to be constituents of the hDPP III substrate binding subsites S1, S1’, S2, S2’ and S3’. The results of this study provide an insight into the coumarinyl Schiff bases inhibitory activity and interactions toward hDPP III.

Molecular docking study was performed to identify new lead inhibitor of SARS-CoV-2 spike glycoprotein (S protein) from the set of 62 peptide derivatives and evaluate their interactions with the receptor. Peptide-type compounds are previously proven peptide-type SARS- CoV 3CL protease inhibitors. However, highest binding affinity towards S protein has compound 21 (E = -127.2 kcal/mol), which showed the very low inhibitory activity against SARS- CoV 3CL protease. Compound 21 is in conformation that tightly fits along only the subunit S1, making the interactions with RBD and SD2 residues. Formation of a cluster of H- atom acceptor (O and N atoms), allows stronger binding to S1 subdomain. Antiviral drug Remdesivir demonstrated low binding affinity toward the S protein. Compounds that interact with receptor binding domain of SARS-CoV-2 spike glycoprotein may be potential therapeutic targets for drug design against COVID-19.

Prior to comercialization of plant protection products, active components must be evaluated regarding their impact on the enviroment, animal and human health. Toxicity research data must be obtained in a laboratory environment by animal testing for long-term and short-term health effects. The REACH (Registration, Evaluation, and Authorization of Chemicals) guidelines implemented by the European Parliament restrict the overusage of animals in testing, and suggest the application of computational softwares in preliminary toxicity predictions. The aim of this research is to estimate the toxicity of the 10 newly synthetized flourinated pyrazole derivatives as potential compounds in plant protection treatments, as they show great prominence as phosphodiesterase inhibitors, making them possibly applicable as future pesticides. The software used to predict the compound toxicity is the T.E.S.T. (Toxicity Estimation Software Tool) software. Toxicity parameters that were evaluated are: • the lethal doses for rats (oral rat LD50) ; • aquatic toxicity (doses for growth inhibition of Tetrahymena pyriformis and lethal doses that kills half of fathead minnow (Pimephales promelas) ; • mutagenicity of compound that induces revertant colony growth of Salmonella typhimurium ; • bioaccumulation factor (the ratio of the concentration of a chemical in the tissue of an aquatic organism (fish) to its concentration in water.

Honey is one of the most precious natural food substances that has been present in human diet dating back to the mesolithic age. By developing awareness of various health benefits along with the rapid development of apitherapy, honey has become the food of choice regarding the prevention of health problems and improving the immune functions of the human body. It is estimated that by year 2025, the market value of honey production and sales will amount to over $ 10 billion. Honey is currently the third most faked food in the world and it is estimated that 30-35% of total honey that is available on the market is adulterated in some way. The use of various syrups, especially those with a high fructose content along with the false declaration of honey are often used methods that lead to the collapse of the prices of natural honey, endangering the market along with the small producers and ultimately final consumers. Detection and prevention of adulterated honey on the market is the area of interest of many laboratories with accredited methods of honey analysis. Significant advances in artificial intelligence and instrumental detection and their implementation in chemical analysis have made it possible to improve the detection of adulterated honey. This paper provides an overview of modern and modified melisopalinological, instrumental and classical chemical methods of honey analysis for the purpose of detection of adulteration.

Acetylcholinesterase (AChE) is an enzyme responsible for the metabolism of acetylcholine (ACh), the neurotransmitter controlling motor activities in nematodes. Inhibition of AChE results in accumulation of ACh at neuromuscular junctions and leads to paralysis, which makes AChE a good target enzyme for the control of parasitic nematodes. AChE inhibitors used to control parasitic nematodes are mainly organophosphates and carbamates, however, due to their toxicity, they have been withdrawn or have restricted usage. Halogenated pyrazoline derivatives exhibit various biological activities, among them antibacterial, antifungal, and antimicrobial. A series of fluorinated pyrazolines was chosen for the investigation of possible AChE inhibition, using Ellman’s protocol modified for microplate reader. All tested compounds exhibited moderate to good inhibitory effect against AChE at 50 μM concentration, with compound 9 (Fig. 1) having the highest inhibition of 79.5 %. A molecular docking study was performed to gain insight into the binding interaction of compound 9 with AChE (PDB: 2c5g). Results show that compound 9 interacts with amino acid residues located in the peripheral active site of AChE, blocking the narrow passage to the catalytic site. The effect of fluorinated pyrazolines was also tested on two entomopathogenic nematodes, Heterorhabditis bacteriophora, and Steinernema feltiae. Entomopathogenic nematodes are beneficial nematodes used in insect pest management programs because of their resilience to pesticide exposure. Since these nematodes mostly have been unaffected by tested compounds, it indicates their potential use as plant protection agents.

Coumarins and their derivatives demonstrate a wide range of biological activities on different organisms. Recently, some of these compounds have been reported as antifungal agents against several pathogenic fungi and applied in agriculture as eco-friendly plant protection agents. QSAR techniques provide insight into relationships between the chemical structure and biological activity and present an alternative pathway for the design and development of new molecules with improved activity. Using this relationship, QSAR models are used to predict the activity of new or untested compounds. The aim of this study was to reveal the physicochemical and structural requirements of newly synthesized coumarinyl derivatives related to their antifungal activity. Series of coumarinyl derivatives has been tested for antifungal activity on two different fungi: Macrophomina phaseolina and Sclerotinia sclerotiorum at the concentration of 0.8 μmol/mL. Results of antifungal assay were evaluated by QSAR analysis in order to provide insight on the quantitative relationship between chemical structure and antifungal activity of these compounds. Most of the assayed compounds showed moderate to good inhibition of mycelial growth for the both examined fungi. The QSAR study has clarified the importance of the presence of pairs: N – C atoms at the topological distance 5, as well as frequency of the pairs of O – O atoms at the topological distance 4, and N – O at the topological distance 9. Also, the presence of 3D- MorSE descriptor weighted with atomic mass implies of importance of three-dimensional distribution of atomic mass. This research represents initial phase in plant protection product development as it helps design new compounds as potential active components of such products.

Human dipeptidyl peptidase III (hDPP III) is a zinc‐hydrolase that cleaves dipeptides from the N‐ terminal of different bioactive peptides. Quinazolinones belong to a diverse class of nitrogen-containing heterocyclic compounds, derivatives of which exhibit a wide range of biological activities. In this research, we selected 10 previously synthesized [1] structuraly different quinazolinone derivatives (QDs) to investigate their potential to inactivate hDPP III activity combining in vitro and in silico approach. The experimental results showed that all analyzed QDs (at the physiological concentration i.e., 100 μM) have inhibitory effect against hDPP III activity. The strongest inhibition (% inh. = 81.9) has been obtained with compound QD8. Molecular docking revealed that hDPP III interacts mostly by hydrogen bonds and hydrophobic interactions with QD8. Among important intermolecular interactions are those with amino acid residues F443, Q446, V447, H568 and R572 that are constituents of hDPP III substrate binding subsites S1, S1’, S2’, and S3’.

In this research main goal was to investigate influence of immobilized cell fermentation on aroma of distillates produced from two grape varieties commonly grown in Croatiian region Istria (Rose Muscat of Poreč and Muscat Blanc). Distillate samples were produced both by classical and immobilized yeast technology. Aroma profile was determined using GC/FID analysis. Results showed that immobilized cell technique gives distillates with higher ethanol and lower ester contents. The immobilized cell technique seems to be promising technique for production of quality marcs distillates.

Spike surface glycoprotein (S protein) is a component of coronavirus virion particle and it is responsible for viral recognition of Angiotensin Converting Enzyme 2 (ACE2). S protein binds with to human ACE2 and uses it as an entry receptor to invade target cells. S1 subunit is responsible for binding to the host cell receptor, while S2 subunit for the fusion of the viral and cellular membranes. SARS-CoV infection could be blocked by inhibitors that bind to the RBD and induced conformational changes in S glycoprotein and prevents binding to the ACE2. Peptide-type compounds were found to have promising activity against SARCoV. Consequently, these molecules attracted the attention of researchers to prepare and test their more derivatives. In order to screen the abilities for binding to the SARS-CoV-2 spike glycoprotein (S protein) of previously proven peptide-type SARS-CoV 3CL protease inhibitors, we performed the molecular docking study. The three dimensional structure of the SARS-CoV-2 spike glycoprotein in complex with N-acetyl-D- glucosamine as ligand (NAG) (pdb: 6VSB) was downloaded from the Protein Data Bank. Molecular docking was performed on 62 optimized structures of compounds (1-62) and antiviral drug Remdesivir. The highest binding affinity towards S protein has compound 21 (E = -127.2 kcal mol-1). Compound 21 is in conformation that forms a cluster of H-atom acceptor (O and N atoms), which allows stronger biding to S1 subdomain. Antiviral drug Remdesivir demonstrated low binding affinity to the S protein.

Med je jedna od najdragocjenijih prirodnih namirnica koja je u ljudskoj svakodnevici prisutna još od mezolitika. Razvijanjem svijesti o brojnim zdravstvenim benefitima te naglim razvojem apiterapije, med je postao namirnica izbora u prevenciji zdravstvenih problema i poboljšanju imunoloških funkcija ljudskog organizma. Procjenjuje se kako će do 2025. godine tržište proizvodnje i prodaje meda težiti nešto više od 10 milijardi USD. Med je trenutačno treća najpatvorenija prehrambena namirnica na svijetu te se procjenjuje kako je 30-35% ukupnog meda na tržištu na neki način krivotvoreno. Korištenje različitih sirupa, prije svega onih visokog sadržaja fruktoze te lažno deklariranje meda često su korištene metode patvorenja koje dovode do rušenja cijena prirodnog meda ugrožavajući tržište i male proizvođače te konačno i krajnje potrošače. Detekcija te prevencija patvorenog meda na tržištu područje je interesa brojnih laboratorija s akreditiranim metodama analize meda. Značajni napretci na području umjetne inteligencije te instrumentalne detekcije omogućuju poboljšanje detekcije patvorenog meda. Ovaj rad pruža pregled u moderne i modificirane melisopalinološke, instrumentalne i klasične kemijske metode analize meda u svrhu detekcije patvorenja.

U ovom radu ispitan je utjecaj dodatka TiO2 nanočestica u rasponu masenih udjela od 1 do 5% na strukturu i svojstva polimerne poliamidne PA 2200 matrice. Polimerni nanokompoziti pripravljeni su postupkom iz taline koristeći Brabender gnjetilicu te hidrauličku prešu Fontune. Karakterizacija uzoraka provedena je diferencijalnom pretražnom kalorimetrijom (DSC), termogravimetrijskom analizom (TGA), metodom istoosnog istezanja te je određena toplinska vodljivost THB metodom. DSC analiza pokazuje kako TiO2 nanopunila poboljšavaju kristalizaciju polimerne matrice, povisuju temperature kristalizacije polimerne matrice odnosno djeluju kao nukleacijski centri. TiO2 punila također pospješuju stvaranje stabilnijih i uređenijih kristalnih struktura. TGA analizom dokazano je da dodatak TiO2 nanopunila povećava temperaturu početka razgradnje PA matrice odnosno poboljšava toplinsko stabilnost PA matrice. Ispitivanjem mehaničkih svojstava uzoraka istoosnim istezanjem vidljivo je kako dodatkom nanopunila dolazi do smanjenja modula te neznatnih promjena čvrstoće i istezanja u točki popuštanja u odnosu na čistu polimernu matricu. Dodatak TiO2 nanočestica povećava vrijednosti toplinske vodljivosti nanokompozita u odnosu na čistu polimernu matricu.

U ovom radu ispitan je utjecaj dodatka TiO2 nanočestica u rasponu masenih udjela od 1 do 5% na strukturu i svojstva polimerne poliamidne PA 2200 matrice. Polimerni nanokompoziti pripravljeni su postupkom iz taline koristeći Brabender gnjetilicu te hidrauličku prešu Fontune. Karakterizacija uzoraka provedena je diferencijalnom pretražnom kalorimetrijom (DSC), termogravimetrijskom analizom (TGA), metodom istoosnog istezanja te je određena toplinska vodljivost THB metodom. DSC analiza pokazuje kako TiO2 nanopunila poboljšavaju kristalizaciju polimerne matrice, povisuju temperature kristalizacije polimerne matrice odnosno djeluju kao nukleacijski centri. TiO2 punila također pospješuju stvaranje stabilnijih i uređenijih kristalnih struktura. TGA analizom dokazano je da dodatak TiO2 nanopunila povećava temperaturu početka razgradnje PA matrice odnosno poboljšava toplinsko stabilnost PA matrice. Ispitivanjem mehaničkih svojstava uzoraka istoosnim istezanjem vidljivo je kako dodatkom nanopunila dolazi do smanjenja modula te neznatnih promjena čvrstoće i istezanja u točki popuštanja u odnosu na čistu polimernu matricu. Dodatak TiO2 nanočestica povećava vrijednosti toplinske vodljivosti nanokompozita u odnosu na čistu polimernu matricu. In this paper, the effect of the addition of TiO2 nanoparticles of a range of 1% wt. to 5% wt. on the structure and properties of PA 2200 polymer matrix was investigated. Polymer nanocomposites were prepared by melting the polymer and mixing the nanoparticles using the Brabender plasticoder and Fontune hydraulic press. The characterization of the samples was performed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tenisle test and thermal conductivity using THB method. DSC analysis shows that TiO2 nanofiller improve the polymer matrix crystallization and increase the crystallization temperature of the polymer matrix by acting as nucleation centres. Additionally, TiO2 nanofiller contribute to the formation of more stable crystal structures. TGA analysis showed that addition of TiO2 nanoparticles shifts the temperature at the beginning of degradation toward higher values, therefore increasing thermal stability of PA matrix. Mechanical properties determined by tensile stress test, imply that by the addition of the TiO2 nanofiller, the secant modulus is reduced. Additionally, slight changes in yield stress and yield strain relative to the pure polymer matrix were observed. The addition of TiO2 nanoparticles increases the thermal conductivity of a nanocomposite relative to a pure polymer matrix.

Znanstveno popularno predavanje o nanotehnologiji, njenim začecima, trenutnom stanju te budućim smjernicama razvitka tehnologije.

Polimerni nanokompoziti kao što su sustavi polimer/kvantne točke u začetcima njihovog istraživanja, prvenstveno su sintetizirani kako bi se pokušala poboljšati svojstva pojedinih komponenti sustava. Ovaj rad daje pregled istraživanja koja se bave sintezom i testiranjem svojstava pojedinih sustava polimer/kvantne točke različitih izvedbi kao što su sustavi polimerni koloidi/kvantne točke, naizmjenični slojevi polimer/kvantne točke, te sustavi s kvantnim točkama u masi polimerima i tankim polimernim filmovima. Različite izvedbe sustava posljedično zahtijevaju različite načine sinteze, koje utječu na različita svojstva i područja primjene sustava polimer/kvantne točke. Pregledom brojnih publikacija koje opisuju istraživanja sustava polimer/kvantne točke, pokazano je kako je kontroliranom sintezom kvantnih točaka, odabirom povoljnog polimera, te jednostavnom pripravom sustava polimer/kvantne točke moguće poboljšati svojstva kvantnih točaka u područjima njihove primjene. At the inception of their research, polymer nanocomposites such as polymer/quantum dots systems were primarily synthesized in order to improve the properties of certain system components. This paper provides an overview of the researches involved in the synthesis and testing of the properties of individual polymer/quantum dots systems of various performances such as polymeric colloids/quantum dots systems, alternating layers of polymer/quantum dots systems, and systems of quantum dots in bulk polymers and thin polymer films. Different system performances therefore require different synthesis modes, which affect the different properties and application areas of the polymer/quantum dots systems. By reviewing numerous publications describing the research of the polymer/quantum dots systems, it has been shown that by using the controllable quantum dot synthesis, selecting the favorable polymer, and using the fairly simple synthesis methods of polymer/quantum dots systems, quantum dot properties can be improved in the areas of their applications.