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Application of gold and selenium nanoparticles for improving L-dopa therapy for Parkinson's disease in Wistar rat
No full textParkinsonova bolest druga je najčešća neurodegenerativna bolest koju karakterizira propadanje dopaminergičnih neurona u supstanciji nigri i, posljedično, manjak dopamina. Terapijski pristupi uglavnom su usmjereni na motoričke simptome i nažalost gube svoju učinkovitost kako neurodegeneracija i simptomi napreduju. Levodopa je trenutačni zlatni standard za liječenje Parkinsonove bolesti, no dugoročna primjena rezultira različitim nuspojavama. Liječenje neurodegenerativnih poremećaja još uvijek predstavlja veliki izazov zbog postojanja krvno-moždane barijere koja otežava efikasnu isporuku lijeka u mozak. Nanotehnologija nudi mogućnosti za poboljšanje terapijskih pristupa zbog sposobnosti nanomaterijala da budu nosači lijekova, da prolaze kroz krvno-moždanu barijeru, poboljšaju farmakološka svojstva i sigurnost lijekova te isporuče lijekove na ciljano mjesto. Nanočestice selena stabilizirane polivinilpirolidonom i nanočestice zlata stabilizirane peptidoglikanskim monomerom ispitane su kao nosači za isporuku levodope s ciljem postizanja neuroprotektivnog učinka. Određivana je njihova sposobnost smanjenja oksidativnog stresa uzrokovanog levodopom u in vivo modelu Parkinsonove bolesti. Štakori oba spola su podijeljeni u 7 skupina i tretirani testnim tvarima tijekom 28 dana. Raspodjela po skupinama bila je nasumična. Oksidativni stres istražen je mjerenjem reaktivnih kisikovih vrsta i koncentracije glutationa u mozgu, bubregu, jetri i serumu tretiranih i netretiranih štakora. Rezultati upućuju na neuroprotektivno djelovanje nanočestica selena. Nanočestice zlata ne pružaju zaParkinson’s disease is the second most common neurodegenerative disease characterized by deteriorating of dopaminergic neurons in the substance of nigra and, consequently, lack of dopamine. Present therapies are focused on reduction of motoric symptoms and sadly lose their efficiency as the neurodegeneration and symtpoms progress. Levodopa is currently a gold standard for curing Parkinson’s disease, but long-term application results in various side effects. Curing neurodegenerative disorders is still a major challenge because of existing blood-brain barrier that complicates efficient transmission of medication into the brain. Nanomaterials have a potential to upgrade therapeutic approaches because of their ability to pass through the blood-brain barrier, to improve pharmacological profile and safety of drugs and to transport drugs to the targeted area. Selenium nanoparticles stabilized by polyvinylpyrrolidone and gold nanoparticles stabilized by peptidoglycan monomer are examined as carriers for the levodopa transmission, with the goal of achieving the neuroprotective effect. Their ability to reduce oxidative stress caused by levodopa is evaluated in an in vivo model of Parkinson’s disease. Rats of both sexes were distributed in 7 groups and tested with test subtances for 28 days. The distribution of animals to the groups was random. Oxidative stress is examined by measuring reactive oxygen species and concentration of glutathione in brain, kidney, liver and serum of non-treated and treated rats. Results indicate a neuroprotective impact of selenium nanoparticles. Gold nanoparticles did not provide protective effect and it is possible that their application has a negative toxicological effects
Multilayered polymer nano-coatings of fatty acids on copper cross-linked by ionizing radiation
No full textSvakodnevni tehnološki napredak omogućava razvoj novih metoda sinteze i karakterizacije materijala, što potiče znanstvenike da istražuju i razvijaju nove i funkcionalnije prevlake koje mogu zadovoljiti specifične potrebe različitih industrija te pri tome biti ekološki prihvatljivi.
U ovom radu ispitana su zaštitna svojstva prevlaka nastalih samoorganizacijom molekula (SAM-ovi) četiri masne kiseline na površini bakra koje su potom umrežene ionizirajućim gama zračenjem. Prevlake neumreženih SAM-ova u korozijskim uvjetima nisu dugotrajno postojane te se relativno brzo uklone s površine. Primjenom gama zračenja inicira se polimerizacija masnih kiselina čime se postiže stabilnija, homogenija i dugotrajnija prevlaka. U ovome radu ispitana su zaštitna svojstva jednostavnih i slojevitih umreženih samoorganiziranih slojeva četiriju masnih kiselina (Crot, C6, C18 i C22) nanošenih metodom uranjanja. Zaštitna svojstva nastalih ispitana su elektrokemijskim metodama (metoda Tafelove ekstrapolacije i elektrokemijska impedancijska spektroskopija-EIS) u otopini koja simulira atmosferske uvjete, a prevlake su dodatno karakterizirane metodom kontaktnog kuta i termogravimetrijskom analizom. Dobiveni rezultati elektrokemijskih ispitivanja su pokazali da od jednostavnih prevlaka C22 prevlake pružaju najbolja zaštitna svojstva, C18 nešto slabija, a C6 najslabija zaštitna svojstva dok prevlake od Crot kiseline stvaraju zaštitu sličnu C22 prevlaci. Ispitivanja na slojevitim prevlakama pokazala su nešto slabija zaštitna svojstva, te od svih ispitivanih prevlaka C22 prevlaka je pokazala najbolja zaštitna svojstva. Vrijednosti kontaktnih kutova određene goniometrijom kod jednoslojnih prevlaka ukazuju na hidrofobnost svih prevlaka osim C6 prevlake, dok su od slojevitih prevlaka jedino kombinacije C6-C18 također hidrofilne, a ostale dvije kombinacije imaju hidrofobna svojstva. Termogravimetrijska analiza pokazuje da se razgradnja jednostavnih prevlaka odvija u jednom stupnju te da maksimalna temperatura raste s porastom duljine lanca. Razgradnja u dva stupnja se javlja kod većine slojevitih prevlaka, uz prvi pad mase bliži temperaturi određenoj za kraću masnu kiselinu, što ukazuje na manju termičku stabilnost u odnosu na jednostavne prevlake C18 i C22.Everyday technological progress enables the development of new methods of material synthesis and characterization, which encourages scientists to research and develop new and more functional coatings that meet the specific needs of different industries while being environmentally friendly. In this work, we tested the protective properties of the coatings created by the self-assembly of molecules (SAMs) of four fatty acids on the surface of copper, which were then cross-linked by ionizing gamma radiation. The coatings of
non-cross-linked SAMs are not long-lasting under corrosive conditions and are removed relatively quickly from the surface. The applying gamma radiation initiates the polymerization of fatty acids, resulting in a more stable, homogeneous and long-lasting coating. In this work, the protective properties of simple and layered cross-linked SAMs of four fatty acids (Crot, C6, C18, and C22) were investigated. The protective properties were tested by electrochemical methods (Tafel extrapolation method and electrochemical impedance spectroscopy-EIS) in a solution simulating atmospheric conditions, and the coatings were additionally characterized by the contact angle method and thermogravimetric analysis.
The results of the electrochemical tests showed that of the simple coatings, the C22 coatings had the best, the C18 coatings the slightly weaker and the C6 coatings the weakest protective properties. The Crot coatings offered only slightly weaker protection compared to the C22 coatings. Tests with layered coatings showed slightly weaker protective properties, and of all the tested coatings the C22 coating showed the best protective properties.
The contact angle values determined by goniometry for single-layer coatings indicate the hydrophobicity of all coatings except the C6 coating, while of the layered coatings, only the C6-C18 combinations are also hydrophilic, and the other two combinations have hydrophobic properties. Thermogravimetric analysis shows that the decomposition of simple coatings takes place in one step and that the maximum temperature increases with the increase in chain length. Degradation in two stages occurs with most layered coatings, with the first drop in mass closer to the temperature determined for the shorter fatty acid, which indicates lower thermal stability compared to simple C18 and C22 coatings
The use of medications with anticholinergic and sedative effects: a cross-sectional study in nursing homes
No full textS obzirom na rastući broj dokaza o rizicima povezanih s primjenom lijekova s antikolinergičkim i sedativnim učincima
kod osoba starije životne dobi, cilj ovog istraživanja bio je utvrditi, korištenjem DBI skale, prevalenciju izloženosti DBI
lijekovima te istražiti povezanost njihove primjene s karakteristikama ispitanika i neželjenim zdravstvenim ishodima
među korisnicima domova za starije i nemoćne u Republici Hrvatskoj.
Presječno istraživanje provedeno je u domovima za starije osobe u tri hrvatske regije između kolovoza i studenog 2022.
godine. U istraživanje je bilo uključeno 225 ispitanika u dobi od 65 i više godina. Podaci su prikupljeni pomoću
standardiziranog interRAI-LTCF upitnika za sveobuhvatnu gerijatrijsku procjenu. Mjere ishoda uključivale su
(ne)ovisnost u obavljanju svakodnevnih aktivnosti (ADLs), skalu kognitivnih sposobnosti (CPS), kliničku skalu krhkosti
(CFS), prisutnost simptoma depresije te broj padova i hospitalizacija. Izloženost lijekovima s antikolinergičkim i
sedativnim učincima izračunata je pomoću DBI (engl. Drug Burden Index) skale, internacionalno validirane mjere za
procjenu opterećenja antikolinergicima i sedativima.
Medijan dobi ispitanika iznosio je 83 (IQR 79-86) godine. Prevalencija izloženosti DBI lijekovima iznosila je 77% te je
bila značajno viša među ispitanicima koji su bili izloženi politerapiji (87%) i prekomjernoj politerapiji (95%) te
ispitanicima sa simptomima depresije (88%). Izloženost DBI lijekovima bila je značajno povezana s lošijim rezultatima
na ADL skali (p=0,036) te većom krhkosti ispitanika (p=0,009). Najupotrebljivaniji DBI lijekovi bili su diazepam (29%
ispitanika), tramadol (29%), zolpidem (18%) i alprazolam (16%).
Uočena je visoka prevalencija izloženosti lijekovima s antikolinergičkim i/ili sedativnim učinkom među korisnicima
domova za starije. Korisnici izloženi DBI lijekovima bili su značajno slabijih funkcionalnih sposobnosti. Ova saznanja
potvrđuju valjanost DBI skale kao jednog od alata za prepoznavanje osoba starije životne dobi pod povećanim rizikom
od funkcionalnog oštećenja te ukazuju na potrebu za unapređenjem upravljanja terapijom korisnika domova za starije
osobe. Visoka prevalencija upotrebe benzodiazepina, „Z lijekova“ i tramadola ukazuje na potrebu za depreskripcijom.Given the increasing evidence of risks of anticholinergic and sedative medications use in older people, the aim of this
study was to determine, using the DBI scale, prevalence of exposure to DBI medications and explore the association of
DBI medications use with participant's characteristics and adverse health outcomes among Croatian nursing homes
residents.
A cross-sectional study was conducted in nursing homes in three Croatian regions between August and November 2022.
The study included 225 participants aged 65 years and older. Data was collected using a standardized interRAI-LTCF
questionnaire for comprehensive geriatric assessment. Outcome measures included (in)dependence in activities of daily
living (ADLs), cognitive performance scale (CPS), clinical frailty scale (CFS), presence of depressive symptoms and
number of falls and hospitalizations. Exposure to anticholinergic and sedative medications was calculated using the
Drug Burden Index (DBI), internationally validated tool that measures the burden of anticholinergic and sedative
medications.
Median age of participants was 83 (IQR 79-86) years. Prevalence of exposure to DBI medications was 77% and it was
significantly higher among participants exposed to polypharmacy (87%) and hyperpolypharmacy (95%) and participants
with symptoms of depression. Exposure to DBI medications was significantly associated with poorer performance on
ADL scale (p=0,036) and higher frailty among participants (p=0,009). The most frequently used DBI medications were
diazepam (29% of participants), tramadol (29%), zolpidem (18%) and alprazolam (16%).
High prevalence of exposure to drugs with anticholinergic and/or sedative effects was observed among nursing home
residents in Croatia. Residents exposed to DBI drugs had significantly poorer functional performance. These findings
confirm the validity of DBI as the tool for identifying older adults at higher risk of functional impairment and indicate
the need for improving pharmacotherapy management of nursing home residents. High use of benzodiazepines, „Zdrugs“ and tramadol suggests there are opportunities for deprescribing
Determination of glucosinolates in Biscutella laevigata and Eruca vesicaria and their isolation using accelerated solvent extraction : diploma thesis
No full textU ovom radu određen je glukozinolatni profil sjemena rokule (Eruca vesicaria) i odabranih biljnih dijelova biokovske i poljske glatke dvoštitke (Biscutella laevigata) izravnom UHPLC-DAD-MS/MS analizom preko odgovarajućih desulfoglukozinolata. Ekstrakcija glukozinolata provedena je sukladno modificiranoj ISO 9167-1 metodi. Dodatno, glukozinolati sjemena rokule izolirani su metodom ubrzane ekstrakcije otapalom pri povišenom tlaku (ASE) s ciljem kvalitativne i kvantitativne usporedbe dobivenih glukozinolata s ISO metodom. Ispitana je ekstrakcijska učinkovitost ASE na temperaturama od 50 ºC, 70 ºC i 90 ºC i s ulaznim količinama biljnog materijala od 1 g i 100 mg. Analizom sjemena rokule, neovisno o primijenjenoj metodi izolacije, dokazana je prisutnost glukoerucina u najvišim koncentracijama (6,13-90,24 μmol/g suhog biljnog materijala). U dosta nižem sadržaju pronađeni su glukorafanin (0,14-1,46 μmol/g) i glukosinalbin (0,13-0,65 μmol/g), a ostali glukozinolati su prisutni u tragovima. Pojedinačni i ukupni (92,35 μmol/g) sadržaji glukozinolata pokazali su se značajno višim primjenom ISO 9167-1 metode. Najveći sadržaj glukozinolata za ASE dobiven je pri temperaturi 70 ºC, tj. 32,57 μmol/g za 1 g i 7,80 μmol/g za 100 mg. Glukohirsutin i glukobrasicin su pronađeni u svim biljnim dijelovima biokovske glatke dvoštitke, a najveći sadržaj bio je u komuški (43,57 μmol/g za glukohirsutin i 14,08 μmol/g za glukobrasicin). Općenito, komuška se pokazala najbogatijom glukozinolatima (57,85 μmol/g), a najsiromašnija je bila stabljika (6,49 μmol/g). Analizom poljske glatke dvoštitke, glukozinolati su ustanovljeni samo u sjemenu unutar kojeg je najsadržajniji bio glukohirsutin (30,51 μmol/g), dok uzorak dobiven in vitro nije sadržavao glukozinolate.In this paper, the glucosinolate profile of rocket seeds (Eruca vesicaria) and selected plant parts of Biokovo and Polish buckler mustard (Biscutella laevigata) was determined using UHPLC-DAD-MS/MS analysis by their desulfo-counterparts. Glucosinolate extraction was performed according to the modified ISO 9167-1 method. Additionally, the glucosinolates of rocket seeds were isolated by accelerated solvent extraction at elevated pressure (ASE) with the aim of comparing the qualitative and quantitative glucosinolate profile with the ISO method. The extraction efficiency of ASE was tested at temperatures of 50 ºC, 70 ºC and 90 ºC with the amounts of plant material of 1 g and 100 mg. The analysis of rocket seeds, regardless of the applied isolation method, revealed the presence of glucoerucin having the highest content (6.13-90.24 μmol/g of dried plant material). Glucoraphanin (0.14- 1.46 μmol/g) and glucosinalbin (0.13-0.65 μmol/g) were found in much lower concentrations, and other glucosinolates were present in traces. Individual and total (92.35 μmol/g) glucosinolate contents were shown to be significantly higher using the ISO 9167-1 method. The highest yield for ASE was obtained at 70 ºC with total glucosinolate content of 32.57 μmol/g for 1 g and 7.80 μmol/g for 100 mg. Glucohirsutin and glucobrassicin were found in all plant parts of buckler mustard from Biokovo and the highest contents were found in siliquae (43.57 μmol/g for glucohirsutin and 14.08 μmol/g for glucobrassicin). In general, siliquae proved to be the richest in glucosinolates (57.85 μmol/g), while the stem had the lowest (6.49 μmol/g). By analyzing the Polish buckler mustard, glucosinolates were found only in the seeds, the most abundant of which was glucohirsutin (30.51 μmol/g), while the glucosinolates were absent in the plant sample obtained in vitro
Control of lubrication system in a steel wire manufacturing plant
No full textU ovome radu opisan je postupak projektiranja sustava za podmazivanje stroja u čeličani. Ukratko je opisano cijelo postrojenje s glavnim dijelovima. Dan je opis procesa podmazivanja, odnosno svi parametri koji moraju biti zadovoljeni. Korištenjem Siemens TIA portala napisan je PLC upravljački program procesa podmazivanja TMB-a. Proces podmazivanje sa svim fizikalnim veličinama (temperatura, tlak ulja) vidljiv je na korisničkom sučelju koje je napravljeno u programu WinCC Explorer V7.0. Cijeli proces je simuliran pomoću Siemens PLCSIM Advanced programa. Na kraju rada opisana je implementacija podmazivanja na TMB stroju, gdje su prikazana sva dopuštenja koja je potrebno zadovoljiti prilikom rada sustava i dan je prikaz alarma koji se javljaju prilikom kvara nekih dijelova sustava.This work describes the process of designing a lubrication system for one of the machines in the steel mill. The entire plant with its main components is briefly described. The lubrication process is described, including all parameters that must be met. Using the Siemens TIA Portal, a PLC control program for the lubrication process of the TMB machine was written. The lubrication process with all physical quantities (temperature, oil pressure) is visible on the user interface created in WinCC Explorer V7.0. The entire process is simulated using the Siemens PLCSIM Advanced program. At the end of the work, the implementation of lubrication on the TMB machine is shown, including all permissions that need to be satisfied during system operation, and alarm displays that occur in case of failure of some system parts are provided
Triaenophorosis in Northern Pike (Esox lucius) from the Mrežnica River
No full textOko 1500 vrsta trakavica parazitira u ribama i neke mogu uzrokovati značajne bolesti.
Među njima treba izdvojiti trakavice roda Triaenophorus i to vrste T. nodulosus i T. crassus,
koje uzrokuju trienoforozu štuke. U crijevu konačnog domaćina, tj. ribi iz porodice Esocidae,
ove odrasle trakavice uzrokuju erozije i ulceracije sluznice praćene staničnom infiltracijom i
fibrozom. Budući da je štuka (E. lucius i E. masquinongy) jedini konačni domaćin trakavice i
da protiv trienoforoze u Republici Hrvatskoj nema registriranog lijeka, smanjenje populacije
štuke u otvorenim vodama, smanjit će učestalost i intenzitet bolesti. U diplomskom radu,
histološkom pretragom crijeva štuke invadirane odraslim trakavicama T. nodulosus, istražena
je patogenost parazita za konačnog domaćina. Materijal za istraživanje porijeklom je iz rijeke
Mrežnice i prikupljen je tijekom 2021. godine u sklopu provedbe projekta Hrvatske zaklade za
znanost („Biomolekule koje vežu metale i zdravstveni poremećaji kod slatkovodnih
organizama izloženih industrijskom otpadu“; šifra projekta IP-2019-04-2636, voditeljica
projekta dr. sc. Zrinka Dragun, Institut Ruđer Bošković).About 1500 tapeworms (Cestoda) parasitise fish, and some of them may cause
important diseases. Among them are cestodes of the genus Triaenophorus, specifically T.
nodulosus and T. crassus, which cause triaenophorosis in pikes (Esox sp.). In northern pike (E.
lucius), their definitive host, these adult tapeworms cause intestinal ulceration with cellular
infiltration and fibrosis. Since in Croatia the northern pike is the only definitive host and there
are no legally approved anthelmintics, the only strategy to control triaenophorosis in natural
waters is to reduce the population of northern pike. In the present study, the pathogenic effect
of adult T. nodulosus was assessed by histological examination. The material (infected fish)
was collected in 2021 at the Mrežnica River. The study was carried out as part of the Croatian
Science Foundation-supported project Metal-binding biomolecules and health disturbances of
freshwater organisms exposed to industrial wastes (IP-2019-04-2636)
The application of the Big Data concept in the knowledge management process
No full textIzvlačenje važnog znanja i informacija iz masivnih baza podataka otvara nove mogućnosti za donositelje odluka i druge dionike u društvu. Velike baze podataka sadrže mnoštvo informacija koje se mogu koristiti za prepoznavanje trendova, dobivanje novih perspektiva i prikupljanje ključnih podataka za informirano donošenje odluka. Ovaj rad istražuje upoznatost organizacija s konceptom Big Data te kako korištenje Big Data tehnologija može doprinijeti razvoju procesa upravljanja znanjem. Svrha rada je istražiti doprinosi li analiza velikih podataka inovacijama i boljim poslovnim odlukama unutar organizacija. Bez znanja, veliki podaci i analitika će propasti jer je upravo znanje omogućilo rast i ostvarivanje stvarnog potencijala velikih podataka. Stručnost ljudi igra važnu ulogu u pravilnim pristupima korištenim za prikupljanje i obradu podataka. Rezultati istraživanja pokazali su da organizacije trebaju ulagati u obuku zaposlenika jer primjena informacija dobivenih iz velikih podataka u operativnim, taktičkim ili strateškim područjima uvelike ovisi o ljudskom razumijevanju.Extracting valuable knowledge and information from massive databases opens up new opportunities for decision-makers and other stakeholders in society. Large databases contain a wealth of information that can be utilized to identify trends, gain new perspectives, and gather key data for informed decision making. This paper explores organizations' familiarity with the concept of Big Data and how the use of Big Data technologies can contribute to the development of knowledge management processes. The purpose of the paper is to investigate whether Big Data analysis contributes to innovation and better business decisions within organizations. Without knowledge, big data and analytics will fail, as it is precisely knowledge that has enabled the growth and realization of the true potential of big data. People's expertise plays a crucial role in the proper approaches used for data collection and processing. The research results have shown that organizations need to invest in employee training because the application of information obtained from Big Data in operational, tactical, or strategic areas largely depends on human understanding
Numerical analysis of the impact load on the side profile of the battery pack of electric vehicle
No full textElektrična vozila predstavljaju novi trend u automobilskoj industriji te sadrže brojne prednosti i nedostatke nad konvencionalnim vozilima. Glavni izazovi električnih vozila vezani su uz baterijski paket, odnosno njegovu sigurnost, masu i domet koje električno vozilo može ostvariti. Upravo zbog toga unutar ovog rada provedena je numerička simulacija udarnog opterećenja na bočni profil s ciljem smanjenja mase profila i povećanje volumena za baterijske ćelije uz zadržavanje mehaničkog integriteta, čime bi se osiguralo povećavanje gustoće energije baterijskog paketa i posljedično tome povećavanja dometa električnog vozila.
Unutar rada je provedeno istraživanje relevantnih normi te istraživanje i analiza trenutnih tržišnih rješenja s naprednom geometrijom bočnog profila koja namijenjena učinkovitoj apsorpciji energije bočnog udara. Na temelju toga modelirana i analizirana je inicijalna geometrija bočnog profila, a potom je geometrija iterirana s ciljem poboljšavanja apsorpcije energije udara i smanjenja pomaka bočnog profila prema unutrašnjosti baterijskog paketa. Za profil s najboljim svojstvima detaljno je prikazana analiza rezultata numeričke simulacije, a potom je i prikazan utjecaj smanjenja dimenzija bočnog profila na povećanje gustoće energije baterijskog paketa.Electric vehicles represent a new trend in the automotive industry, offering numerous advantages and disadvantages compared to conventional vehicles. The main challenges of electric vehicles are related to the battery pack, specifically its safety, weight, and the range the vehicle can achieve. For this reason, this study includes a numerical simulation of impact load on the side profile with the aim of reducing weight and volume while maintaining mechanical integrity, thereby increasing the energy density of the battery pack and, consequently, the range of the electric vehicle.
The study also involved researching relevant standards and analyzing current market solutions with advanced side profile geometries designed for effective energy absorption during side impacts. Based on this, the initial geometry of the side profile was modeled and analyzed, followed by iterative geometry modifications aimed at improving energy absorption and reducing the inward displacement of the side profile toward the battery pack. For the profile with the best properties, a detailed analysis of the numerical simulation results is presented, as well as the impact of reducing the side profile dimensions on increasing the energy density of the battery pack
Physical nature of deformation during cold plastic deformation
No full textPoznavanje fizikalne prirode deformacije ima veliku važnost u razumijevanju procesa koji se odvijaju u metalnim materijalima tijekom plastične deformacije. Pritom mikrostrukturne promjene imaju utjecaj na iznose i raspodjelu naprezanja i deformacija čije poznavanje ima ključnu važnost kod oblikovanja deformiranjem metalnih materijala. U ovom radu provedena su istraživanja promjena mikrostrukture niskougljičnog čelika tijekom hladne plastične deformacije. Ispitivanja su provedena istovremenim korištenjem metoda statičkog vlačnog ispitivanja, termografije i digitalne korelacije slike (DIC). Uz navedene metode korištene su metode za analizu mikrostrukture odnosno svjetlosni i transmisijski elektronski mikroskop (TEM). Detaljnija analiza mikrostrukture i dislokacija tijekom hladne plastične deformacije provedena je korištenjem dva različita operacijska moda TEM - a i skenirajućeg TEM - a (STEM). Promjene temperature (naprezanja), deformacije i brzine deformacije u zoni deformacije dobivene metodama termografije i DIC tijekom statičkog vlačnog ispitivanja odnosno plastične deformacije povezane su s promjenama u mikrostrukturi dobivenim metalografskom analizom na svjetlosnom mikroskopu i transmisijskom elektronskom mikroskopu. Tijekom promatranja mikrostrukture naglasak je bio na analizi gustoće dislokacija tijekom plastične deformacije. Identificirane su mikrostrukturne promjene koje se javljaju tijekom hladne plastične deformacije. Utvrđena su mjesta najznačajnijeg očvršćavanja i gustoće dislokacija tijekom hladne deformacije niskougljičnog čelika.The knowledge of the physical nature of deformation is of great importance in understanding the processes that occur in metallic materials during plastic deformation. Microstructural changes have an impact on the stress and strain amounts and distribution which is of key importance in metal forming. In this work, research was conducted on microstructure changes of low-carbon steel during cold plastic deformation. The tests were carried out using the methods of static tensile testing, thermography and digital image correlation (DIC). In addition to the above methods, for microstructure analysis were used: light and transmission electron microscope (TEM). A more detailed analysis of the microstructure and dislocations during cold plastic deformation was carried out using two different operating modes of TEM and scanning TEM (STEM). Changes in temperature (stress), strain and strain rate in the deformation zone, obtained by the methods of thermography and DIC during static tensile testing (plastic deformation), are related to the microstructure changes obtained by metallographic analysis on a light microscope and a transmission electron microscope. The emphasis was on the analysis of dislocation density during plastic deformation. Microstructural changes that occur during cold plastic deformation were identified. The locations of the most significant hardening and dislocation density during cold deformation of low-carbon steel were determined
Chemical analysis of honey : diploma thesis
No full textU ovom diplomskom radu analizirane su fizikalno – kemijske karakteristike 33 uzorka meda i patvorine meda različitog botaničkog i geografskog podrijetla. Određena je njihova kiselost, električna vodljivost, sadržaj pepela i vode te koncentracija minerala i teških metala. Primjenom tehnike masene spektrometrije s induktivno spregnutom plazmom (ICP-MS) određeni su glavni elementi (Ca, K, Mg, Na, P i S) te elementi i ultra-elementi u tragovima (Ag, Al, As, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Si, Sn, Sr, Ti, Tl i Zn). Iz dobivenih rezultata i njihovom usporedbom s važećom zakonskom regulativom izmjerena vrijednost električne vodljivosti kod jednog uzorka je viša, a kod dva uzorka niža od vrijednosti električne vodljivosti propisane Pravilnikom o medu. Kod rezultata sadržaja vode u medu jedan uzorak nije u skladu s Pravilnikom o medu. Izmjerene koncentracije teških metala kod devet uzoraka ne zadovoljavaju zakonsku regulativu, odnosno izmjerene koncentracije prelaze najviše dopuštene količine (NDK) prema Pravilniku o toksinima, metalima, metaloidima, te drugim štetnim tvarima koje se mogu nalaziti u hrani. Jedan uzorak cvjetnog meda pokazao je najviše razine većine minerala i teških metala u usporedbi s drugim uzorcima. Ova analiza ključna je za osiguranje kvalitete i sigurnosti meda, naglašavajući potrebu za strogim nadzorom i poštivanjem propisa o sigurnosti hrane.In this diploma thesis, the physico-chemical properties of 33 honey samples, including adulterated honey, from different botanical and geographical areas of origin were analyzed. Acidity, electrical conductivity, ash, water content and concentration of minerals and heavy metals were determined. The concentrations of major elements (Ca, K, Mg, Na, P and S), trace elements and ultraelements (Ag, Al, As, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, Rb, Sb, Se, Si, Sn, Sr, Ti, Tl and Zn) were determined using the inductively coupled plasma mass spectrometry (ICP-MS) technique. The results showed that three samples did not meet the standards for electrical conductivity and one sample did not meet the legal requirements for the water content of honey. The heavy metal concentrations in nine samples did not meet the legal standards. In particular, one sample of blossom honey had the highest levels of most minerals and heavy metals compared to the other samples. This analysis is crucial for ensuring the quality and safety of honey and underlines the need for strict monitoring and compliance with food safety regulations