Monitoring concentration and magnetic field influence on asphaltene aggregation by NMR spectroscopy

Asfalteni predstavljaju najteže, najmanje reaktivne i najpolarnije frakcije sirove nafte. Sastoje se od aromatskih molekula supstituiranih alifatskim lancima, heteroatomima N, S i O te metala u tragovima, poput V, Ni i Fe. Ove kompleksne makromolekule sklone su stvaranju agregata, što uzrokuje poteškoće prilikom proizvodnje i transporta nafte. Agregacija asfaltena iz vakuumskog ostatka sirove nafte je u ovome radu proučavana spektroskopijom NMR korištenjem tehnika inverznog oporavka i DOSY NMR. OdreĎeno je koncentracijsko područje u kojem nastaju agregati u toluenu te je istražen utjecaj porfirina vanadija(IV), nikla(II) i željeza(III) na vrijednosti difuzijskih koeficijenata, relaksaciju i agregaciju asfaltena. Nakon dodatka porfirina nije zapažen utjecaj na difuzijske koeficijente i agregaciju, dok je izmjereno značajno smanjenje longitudinalnog vremena relaksacije jezgre 1H zbog paramagnetnog doprinosa metala. Na temelju izmjerenih difuzijskih koeficijenata izračunati su hidrodinamički radijusi i molekulske mase monomera i agregata asfaltena. Očekuje se da će dobiveni rezultati pridonijeti boljem razumijevanju procesa agregacije ovih spojeva.Aspahltenes represent the heaviest, least reactive and most polar fraction of crude oil. They consist of aromatic molecules substituted by aliphatic chains, heteroatoms N, S and O and trace amounts of metals, such as Ni, V and Fe. These complex macromolecules tend to form aggregates causing many problems in crude oil production and transportation. In this reserch, aggregation behavior of asphaltenes obtained from vaccum residue of crude oil distillation was investigated by applying inversion recovery and DOSY NMR techniques. The lowest aggregation concentration in toluene was determined and the influence of V(IV), Ni(II) and Fe(III) porphyrins on diffusion coefficient, relaxation and aggregation process was studied. The addition of metalloporphyrins significantly decreased longitudinal relaxation time due to the paramagnetic contribution, but no effect on diffusion coefficient was observed in used concentration range. Hydrodynamic radii and molecular weights of the studied compounds were calculated from their diffusion coefficients. It is expected that the presented results will contribute to better understanding the asphaltene aggregation process

Monitoring concentration and magnetic field influence on asphaltene aggregation by NMR spectroscopy

Asfalteni predstavljaju najteže, najmanje reaktivne i najpolarnije frakcije sirove nafte. Sastoje se od aromatskih molekula supstituiranih alifatskim lancima, heteroatomima N, S i O te metala u tragovima, poput V, Ni i Fe. Ove kompleksne makromolekule sklone su stvaranju agregata, što uzrokuje poteškoće prilikom proizvodnje i transporta nafte. Agregacija asfaltena iz vakuumskog ostatka sirove nafte je u ovome radu proučavana spektroskopijom NMR korištenjem tehnika inverznog oporavka i DOSY NMR. OdreĎeno je koncentracijsko područje u kojem nastaju agregati u toluenu te je istražen utjecaj porfirina vanadija(IV), nikla(II) i željeza(III) na vrijednosti difuzijskih koeficijenata, relaksaciju i agregaciju asfaltena. Nakon dodatka porfirina nije zapažen utjecaj na difuzijske koeficijente i agregaciju, dok je izmjereno značajno smanjenje longitudinalnog vremena relaksacije jezgre 1H zbog paramagnetnog doprinosa metala. Na temelju izmjerenih difuzijskih koeficijenata izračunati su hidrodinamički radijusi i molekulske mase monomera i agregata asfaltena. Očekuje se da će dobiveni rezultati pridonijeti boljem razumijevanju procesa agregacije ovih spojeva.Aspahltenes represent the heaviest, least reactive and most polar fraction of crude oil. They consist of aromatic molecules substituted by aliphatic chains, heteroatoms N, S and O and trace amounts of metals, such as Ni, V and Fe. These complex macromolecules tend to form aggregates causing many problems in crude oil production and transportation. In this reserch, aggregation behavior of asphaltenes obtained from vaccum residue of crude oil distillation was investigated by applying inversion recovery and DOSY NMR techniques. The lowest aggregation concentration in toluene was determined and the influence of V(IV), Ni(II) and Fe(III) porphyrins on diffusion coefficient, relaxation and aggregation process was studied. The addition of metalloporphyrins significantly decreased longitudinal relaxation time due to the paramagnetic contribution, but no effect on diffusion coefficient was observed in used concentration range. Hydrodynamic radii and molecular weights of the studied compounds were calculated from their diffusion coefficients. It is expected that the presented results will contribute to better understanding the asphaltene aggregation process

Preparation and reactions of nitriles

Nitrili su organski spojevi, široko rasprostranjeni u prirodi, sintetskim materijalima te lijekovima. Nitrili se mogu sintetizirati u laboratoriju te izolirati iz prirodnih materijala. U uvodu su navedena pravila imenovanja nitrila te osnovna fizikalna i kemijska svojstva. Nakon uvoda, u poglavlju Priprava nitrila opisane su neke laboratorijske i industrijske metode za sintezu odgovarajućih nitrila. Obrađene su sljedeće metode: cijanhidrinska reakcija, adicija cijano skupine na ,-nezasićene karbonilne spojeve, nukleofilna supstitucija halogenalkana cijanidom, Sandmeyerova reakcija, dehidratiranje amida i oksima, priprava nitrila iz zasićenih i nezasićenih ugljikovodika. Sljedeće poglavlje se odnosi na reaktivnost nitrila, obrađeni su mehanizmi reakcije hidrolize katalizirane kiselinom i bazom, redukcija nitrila katalitičkim hidrogeniranjem i kompleksnim metalnim hidridima, Grignardova reakcija te alkiliranje i aciliranje nitrila. U zadnjem poglavlju je opisana primjena nitrila u farmaciji i proizvodnji industrijski važnih materijala, te njihova zastupljenost u prirodnim spojevima

Morphometric and meristic characteristics of poor cod, Trisopterus minutus (L. 1758), from the eastern central Adriatic Sea

Background and Purpose: Poor cod, Trisopterus minutus (Linnaeus, 1758) is a gadoid fish, which inhabits the Mediterranean and eastern Atlantic. The aim of present work was to investigate the morphological properties of poor cod in the eastern central Adriatic Sea by analyzing classical morphometric and meristic characteristics, and thereby investigating: a) whether there are morphological differences between males and females; b) the existence of possible homogenous or heterogeneous stock morphology; and c) the changes in morphometric characteristics with increase in body length.Material and methods: Samples of 410 poor cod specimens (209 females, 201 males) were collected by bottom-trawl between 2014 and 2016 from five localities in the eastern central Adriatic Sea. In order to analyze biometry of the species; fifteen morphometric and eight meristic characteristics were measured.Results and Conclusions: Total length of all specimens ranged from 8.8 to 27.1 cm. Morphological differences between males and females was not marked. Biometric analysis of the morphometric and meristic characteristics indicated a homogenous morphology stock of Trisopterus minutus in the Adriatic Sea. Changes in some morphometric characteristics obtained in conjunction with an increase in body length showed that smaller specimens have a longer head, eye diameter, ventral fins and second anal fins than adult specimens. The negative correlation recorded for the maximum and minimum body depth indicated that the body elongated with poor cod growth. Comparison of the meristic characteristics that were published earlier show some differences between the poor cod populations inhabiting the Adriatic, Black Sea and eastern Atlantic.</p

Rapid Structure Determination of Bioactive 4''-tetrahydrofurfuryl Macrozone Reaction Mixture Components by LC/SPE/Cryo NMR and MS

LC-SPE/cryo NMR and MS methodologies have been developed and employed for a rapid structure determination of 4″-tetrahydrofurfuryl macrozone reaction mixture components. Macrozones, novel conjugates of azithromycin, and thiosemicarbazones have shown very good in vitro antibacterial activities against susceptible and some resistant bacterial strains and are promising agents for further development. The post-column multiple trapping of the chromatographically separated reaction mixture components on the SPE cartridges increased the sensitivity and together with cryogenically cooled NMR probe made it possible to identify and structurally characterize main 4″- tetrahydrofurfuryl macrozone reaction mixture compounds including those present at very low concentration level. This approach has several advantages over a classical off-line procedure, efficiency and low solvent consumption being the two most important ones. All identified components were process-related. It has been demonstrated that two different kinds of compounds with respect to structure were identified, i.e., macrolide- related and thiosemicarbazone-related ones. This methodology can serve as a platform for reliable and effective macrolides reaction components structure profiling, serving as both isolation and identification tools

Preparation, characterization and biologial activity of macrozones, new azithromycin derivatives

Značajan porast bakterijske rezistencije utječe na sve veću potrebu za istraživanjem i razvojem novih antibiotika. U sklopu ovog rada pripravljene su tri nove klase makrozona, konjugata makrolidnog antibiotika azitromicina i tiosemikarbazona. Tiosemikarbazoni su korišteni za kemijsku modifikaciju azitromicina na tri različita položaja. Cilj rada je priprava novih derivata makrolida sa širim spektrom biološke aktivnosti. Pripravljenim spojevima određena je biološka aktivnost in vitro na susceptibilne i rezistentne Gram-pozitivne i Gram-negativne bakterije te su istražene interakcije s biološkim receptorima. Za proučavanje interakcija primijenjena je spektroskopija NMR, cirkularni dikroizam, fluorescencijska spektroskopija i molekulsko modeliranje. Makrozoni su pokazali zadovoljavajuću biološku aktivnost, posebice na neke rezistentne bakterijske sojeve na koje azitromicin nije aktivan. Rezultati dobiveni spektroskopskim metodama i molekulskim modeliranjem ukazuju na odnos strukture i aktivnosti novih derivata azitromicina, što može poslužiti za dizajn i otkriće biaktivnijih derivata makrolida.Owing to a significant increase in bacterial resistance, a high need for discovery and development of new antibiotics has emerged. As part of this work, three novel classes of macrozones, conjugates of macrolide antibiotic azithromycin and thiosemicarbazones, were prepared. Thiosemicarbazones were used to chemically modify azithromycin at three different positions. The aim of this thesis was to prepare compounds with a wider range of biological activity including resistant bacterial strains. In vitro biological activity of the prepared compounds was determined against susceptible and resistant Gram-positive and Gram-negative bacteria, and interactions with biological receptors were investigated. Macrozones showed satisfactory biological activity, especially against some resistant bacterial strains to which azithromycin is inactive. NMR spectroscopy, circular dichroism, fluorescence spectroscopy, and molecular modeling were further used to study interactions of selected compounds with biological targets. The results obtained by spectroscopic methods and molecular modeling indicate a relationship between structure and activity of new azithromycin derivatives, which can be used for design and discovery of more active macrolide derivatives

Monitoring concentration and magnetic field influence on asphaltene aggregation by NMR spectroscopy

Asfalteni predstavljaju najteže, najmanje reaktivne i najpolarnije frakcije sirove nafte. Sastoje se od aromatskih molekula supstituiranih alifatskim lancima, heteroatomima N, S i O te metala u tragovima, poput V, Ni i Fe. Ove kompleksne makromolekule sklone su stvaranju agregata, što uzrokuje poteškoće prilikom proizvodnje i transporta nafte. Agregacija asfaltena iz vakuumskog ostatka sirove nafte je u ovome radu proučavana spektroskopijom NMR korištenjem tehnika inverznog oporavka i DOSY NMR. OdreĎeno je koncentracijsko područje u kojem nastaju agregati u toluenu te je istražen utjecaj porfirina vanadija(IV), nikla(II) i željeza(III) na vrijednosti difuzijskih koeficijenata, relaksaciju i agregaciju asfaltena. Nakon dodatka porfirina nije zapažen utjecaj na difuzijske koeficijente i agregaciju, dok je izmjereno značajno smanjenje longitudinalnog vremena relaksacije jezgre 1H zbog paramagnetnog doprinosa metala. Na temelju izmjerenih difuzijskih koeficijenata izračunati su hidrodinamički radijusi i molekulske mase monomera i agregata asfaltena. Očekuje se da će dobiveni rezultati pridonijeti boljem razumijevanju procesa agregacije ovih spojeva.Aspahltenes represent the heaviest, least reactive and most polar fraction of crude oil. They consist of aromatic molecules substituted by aliphatic chains, heteroatoms N, S and O and trace amounts of metals, such as Ni, V and Fe. These complex macromolecules tend to form aggregates causing many problems in crude oil production and transportation. In this reserch, aggregation behavior of asphaltenes obtained from vaccum residue of crude oil distillation was investigated by applying inversion recovery and DOSY NMR techniques. The lowest aggregation concentration in toluene was determined and the influence of V(IV), Ni(II) and Fe(III) porphyrins on diffusion coefficient, relaxation and aggregation process was studied. The addition of metalloporphyrins significantly decreased longitudinal relaxation time due to the paramagnetic contribution, but no effect on diffusion coefficient was observed in used concentration range. Hydrodynamic radii and molecular weights of the studied compounds were calculated from their diffusion coefficients. It is expected that the presented results will contribute to better understanding the asphaltene aggregation process

THE INSURANCE OF PROPERTY AND EMPLOYEES IN THE CASE OF TOMMY D.O.O.

Početak samog osiguranja seže daleko u prošlost, a do danas se razvila do najmanjih detalja prvobitno da bi zaštitila svoje korisnike pa i njene davaoce. Mnogobrojni trgovci, trgovine i trgovački lanci u svom poslovanju se susreću s raznim vrstama osiguranja. U današnje vrijeme trgovcima su rad i poslovanje olakšani velikim izborom pravog osiguranja za njihovo poslovanje. Osiguranje imovine i zaposlenika trgovcu nudi sigurnije poslovanje. Zaposleniku mirovinsko i zdravstveno osiguranje nudi sigurnost u sadašnjosti i budućnosti za sebe i za članove svoje obitelji. U ovom radu upoznajemo se s vrstama osiguranja potrebnih trgovačkom poduzeću za poslovanje u skladu sa zakonima Republike Hrvatske. Upoznati ćemo se s poslodavcem Tommy d.o.o. njegovom poviješću i sadašnjim stanjem poslovanja te osiguranjima koja mu pomažu poslovanje održati na visokom položaju.The origin of insurance itself dates far back into the past, and nowadays it has developed to the smallest details, mainly to protect its clients as well as its providers. Numerous vendors, markets and chain stores encounter various types of insurance in their business activities. Today, work and trade are facilitated with a wide range of perfect insurance for their conduct. Property and employee insurance offers a safer conduct of business to the trader, and retirement and health insurance offers stability in the present as well as in the future to the employee and their family. In this paper we will encounter types of insurance required for a commercial enterprise to conduct business in compliance with the laws of the Republic of Croatia. We will familiarise ourselves with the employer of Tommy d.o.o., its history and the current state of business as well as the insurances that help maintain its operations at a high position

Preparation, characterization and biologial activity of macrozones, new azithromycin derivatives

Značajan porast bakterijske rezistencije utječe na sve veću potrebu za istraživanjem i razvojem novih antibiotika. U sklopu ovog rada pripravljene su tri nove klase makrozona, konjugata makrolidnog antibiotika azitromicina i tiosemikarbazona. Tiosemikarbazoni su korišteni za kemijsku modifikaciju azitromicina na tri različita položaja. Cilj rada je priprava novih derivata makrolida sa širim spektrom biološke aktivnosti. Pripravljenim spojevima određena je biološka aktivnost in vitro na susceptibilne i rezistentne Gram-pozitivne i Gram-negativne bakterije te su istražene interakcije s biološkim receptorima. Za proučavanje interakcija primijenjena je spektroskopija NMR, cirkularni dikroizam, fluorescencijska spektroskopija i molekulsko modeliranje. Makrozoni su pokazali zadovoljavajuću biološku aktivnost, posebice na neke rezistentne bakterijske sojeve na koje azitromicin nije aktivan. Rezultati dobiveni spektroskopskim metodama i molekulskim modeliranjem ukazuju na odnos strukture i aktivnosti novih derivata azitromicina, što može poslužiti za dizajn i otkriće biaktivnijih derivata makrolida.Owing to a significant increase in bacterial resistance, a high need for discovery and development of new antibiotics has emerged. As part of this work, three novel classes of macrozones, conjugates of macrolide antibiotic azithromycin and thiosemicarbazones, were prepared. Thiosemicarbazones were used to chemically modify azithromycin at three different positions. The aim of this thesis was to prepare compounds with a wider range of biological activity including resistant bacterial strains. In vitro biological activity of the prepared compounds was determined against susceptible and resistant Gram-positive and Gram-negative bacteria, and interactions with biological receptors were investigated. Macrozones showed satisfactory biological activity, especially against some resistant bacterial strains to which azithromycin is inactive. NMR spectroscopy, circular dichroism, fluorescence spectroscopy, and molecular modeling were further used to study interactions of selected compounds with biological targets. The results obtained by spectroscopic methods and molecular modeling indicate a relationship between structure and activity of new azithromycin derivatives, which can be used for design and discovery of more active macrolide derivatives

Preparation, characterization and biologial activity of macrozones, new azithromycin derivatives

Značajan porast bakterijske rezistencije utječe na sve veću potrebu za istraživanjem i razvojem novih antibiotika. U sklopu ovog rada pripravljene su tri nove klase makrozona, konjugata makrolidnog antibiotika azitromicina i tiosemikarbazona. Tiosemikarbazoni su korišteni za kemijsku modifikaciju azitromicina na tri različita položaja. Cilj rada je priprava novih derivata makrolida sa širim spektrom biološke aktivnosti. Pripravljenim spojevima određena je biološka aktivnost in vitro na susceptibilne i rezistentne Gram-pozitivne i Gram-negativne bakterije te su istražene interakcije s biološkim receptorima. Za proučavanje interakcija primijenjena je spektroskopija NMR, cirkularni dikroizam, fluorescencijska spektroskopija i molekulsko modeliranje. Makrozoni su pokazali zadovoljavajuću biološku aktivnost, posebice na neke rezistentne bakterijske sojeve na koje azitromicin nije aktivan. Rezultati dobiveni spektroskopskim metodama i molekulskim modeliranjem ukazuju na odnos strukture i aktivnosti novih derivata azitromicina, što može poslužiti za dizajn i otkriće biaktivnijih derivata makrolida.Owing to a significant increase in bacterial resistance, a high need for discovery and development of new antibiotics has emerged. As part of this work, three novel classes of macrozones, conjugates of macrolide antibiotic azithromycin and thiosemicarbazones, were prepared. Thiosemicarbazones were used to chemically modify azithromycin at three different positions. The aim of this thesis was to prepare compounds with a wider range of biological activity including resistant bacterial strains. In vitro biological activity of the prepared compounds was determined against susceptible and resistant Gram-positive and Gram-negative bacteria, and interactions with biological receptors were investigated. Macrozones showed satisfactory biological activity, especially against some resistant bacterial strains to which azithromycin is inactive. NMR spectroscopy, circular dichroism, fluorescence spectroscopy, and molecular modeling were further used to study interactions of selected compounds with biological targets. The results obtained by spectroscopic methods and molecular modeling indicate a relationship between structure and activity of new azithromycin derivatives, which can be used for design and discovery of more active macrolide derivatives