Certificiranje i sigurnost pri ispitivanju metalnih materijala kod nerazornih metoda

Ispitivanja materijala metodama bez razaranja (eng. Non-destructive testing - NDT) rade se s ciljem otkrivanja grešaka u materijalima, a da se pri tome ispitivani metalni materijali ne oštete. Osim utvrđivanja grešaka ovim metodama kod ispitivanja metalnih materijala, omogućeno je i određivanje svojstava grešaka kao što su veličina i oblik greške, te dubina na kojoj se greška nalazi. Obzirom na važnost ispitivanja metalnih materijala nerazornim metodama vrlo je važno da ovu vrstu ispitivanja provode certificirani djelatnici obzirom na kvalitetu provedenih ispitivanja te sigurnost osoblja koje provodi ispitivanja. U ovom završnom radu prikazan je postupak pripreme osoblja tvrtke STSI d.o.o. za postupak certifikacije u području nerazornih ispitivanja na primjeru ispitivanja magnetskom metodom. Ujedno je navedena i važnost korištenja zaštitne opreme i moguće opasnosti pri ispitivanju magnetskom metodom.Testing of materials using non-destructive methods (Non-destructive testing - NDT) is done with the aim of detecting defects in the materials, without damaging the tested metal materials. In addition to the determination of defects, these methods allow the determination of the properties of the defects, such as the size and shape of the defect, and the depth at which the defect is located during testing metal materials. Considering the importance of testing materials using non-destructive methods, it is very important that this type of testing is carried out by certified personnel, considering the quality of the tests carried out and the safety of personnel that performing testing. This paper presents the process of the staff preparing in STSI Ltd. for the certification procedure in the field of non-destructive testing on the example of testing with the magnetic method. The importance of using protective equipment and the possible dangers of testing with the magnetic method are mentioned as well

Effect of melt retention after treatment on the final quality of nodular cast iron HR GJS 400-15

Nodularni lijev HRN-EN-GJS-400-15 koristi se u automobilskoj industriji za izradu dijelova poput zupčanika, diferencijala i osovina zbog svoje visoke čvrstoće i dobre žilavosti. Konstantnim rastom potražnje kupci postavljaju sve veće zahtjeve za kvalitetnijim proizvodima. Da bi proizvođači to ispunili, važno je konstantno kontrolirati kemijski sastav, minimalizirati eventualne greške u mikrostrukturi i modificirati postupke proizvodnje. U ovom završnom radu prati se proizvodnja odljevaka iz HRN-EN-GJS-400-15, točnije utjecaj vremena zadržavanja taline nakon obrade u loncu na konačnu kvalitetu nodularnog lijeva. U procesu proizvodnje odlivene su dvije Y probe na kojima su provedena ispitivanja. Provedena su ispitivanja kemijskog sastava, mehaničkih svojstava i strukture nodularnog lijeva. Usporedbom rezultata svojstava, na početku i kraju lijevanja, uočava se kako pri kraju lijevanja dolazi do smanjenja u mehaničkih svojstava. Analiza strukture ukazuje kako se radi o željeznom lijevu s pretežno feritnom osnovom. Prema kraju lijevanja postupno raste udio perlita.Ductile iron, or nodular cast iron, HRN-EN-GJS-400-15 is used in the automotive industry to make parts such as gears, differentials and axles due to its high strength and good toughness. Demands on quality are constantly growing, customers are setting higher and higher demands. In order for manufacturers to fulfill this, it is important to constantly control the chemical composition and minimize possible defects in the microstructure, and to modify production procedures in order to increase production and reduce costs. In this final paper, the production of ductile iron HRN-EN-GJS-400-15 is monitored, specifically the influence of the melt retention time in the casting ladle on the final quality of ductile iron. Two Y-shaped cast samples were cast in the production process. Chemical composition, mechanical properties and structure of nodular cast iron were tested. By comparing the results of the properties, at the beginning and end of casting, it is observed that near the end there is a drop in the mechanical properties. Analysis of the microstructure indicates that matrix of cast iron is predominantly ferrite base. Towards the end of the process, the proportion of pearlite gradually increases

Application of metallographic replicas during plastic deformation of low carbon steel

Poznavanje raspodjele naprezanja i deformacija te promjene u mikrostrukturi od ključne su važnosti za razumijevanje procesa koji se odvijaju tijekom plastične deformacije, odnosno oblikovanja deformiranjem u industrijskoj proizvodnji. Raspodjela promjene temperature, odnosno naprezanja, i deformacija danas se mogu detaljno odrediti metodama termografije i digitalne korelacije slike (eng. DIC - digital image correlation). Kako bi se odredile promjene u mikrostrukturi koje se javljaju tijekom plastične deformacije korištena je metoda metalografskih replika. Obzirom na vrlo kompleksnu i složenu pripremu ispitnih uzoraka za istovremeno ispitivanje metodama statičkog vlačnog ispitivanja, termografije, digitalne korelacije slike i metalografskim replikama u ovom istraživanju provedeno je ispitivanje mogućnosti primjene metalografskih replika na niskougljičnom čeliku tijekom hladne plastične deformacije uz istovremeno korištenje prehodno navedenih metoda. U odabranim točkama ispitivanja uzimane su metalografske replike s ispitne površine nakon čega je provedena analiza mikrostrukture niskougljičnog čelika. Analiza mikrostrukture i primjena metalografskih replika u ovom radu povezana je s promjenama temperature odnosno naprezanjima i deformacijama niskougljičnih čelika dobivenih metodama termografije i digitalne korelacije slike. Istraživanja su pokazala da je moguće primijeniti istovremeno metode statičkog vlačnog ispitivanja, digitalne korelacije slike, termografije i metalografskih replika tijekom plastične deformacije niskougljičnog čelika. Utvrđeno je da je s ovim načinom ispitivanja moguće, bez razaranja materijala, ispitati i povezati raspodjelu promjena temperature, odnosno naprezanja, i deformacija te mikrostrukturne promjene tijekom plastične deformacije niskougljičnog čelika, ali i ostalih metalnih materijala. Zaključeno je da se ispitivanjem mikrostrukture metalografskim replikama mogu utvrditi promjene koje su posljedice utjecaja hladne plastične deformacije.The knowledge of stress and strain distribution and microstructural changes has a great importance for understanding the processes of plastic deformation during metal forming in industrial production. Today, the distribution of temperature changes, i.e. stress, and strains can be determined in detail using thermography and digital image correlation (DIC - digital image correlation). In order to determine the microstructure changes that occur during plastic deformation, the method of metallographic replicas was used. In this study, the possibility of applying metallographic replicas to low-carbon steel during cold plastic deformation using static tensile testing, thermography, digital image correlation and metallographic replicas simultaneously was tested, as the sample preparation for simultaneous testing with the aforementioned methods is very complex. At the selected test points, metallographic replicas were taken from the test surface and the microstructure analysis of the low-carbon steel was performed. In this work, microstructural analysis and the application of the metallographic replicas are related to the temperature changes, i.e. the stresses and strains of the low-carbon steel obtained by thermography and digital image correlation. Research has shown that it is possible to simultaneously apply static tensile testing, digital image correlation, thermography and metallographic replicas during the plastic deformation of low-carbon steel. It was found that with these test methods it is possible to investigate and relate the temperature changes, i.e. the stress and strain distribution and the microstructural changes during plastic deformation of low-carbon steels, but also of other metallic materials, without destroying the material. It was found that by examining the microstructure with metallographic replicas, it is possible to determine the changes that can be attributed to the influence of cold plastic deformation

Risk assessment of physical hazards at the workplace of a police officer

Završni rad istražuje različite elemente poslova policije, s posebnim naglaskom na rizike kojima su policijski službenici izloženi tijekom obavljanja svojih dužnosti. Rad je podijeljen u nekoliko ključnih dijelova. U prvom dijelu, razmatraju se različite vrste poslova u policiji, uključujući prometnu, temeljnu, graničnu i kriminalističku policiju. Drugi dio rada analizira rizike na radnom mjestu, kako na svjetskoj razini, tako i specifično za policijske službenike. Osim toga, detaljno se razmatraju fizikalne štetnosti kojima su policajci izloženi, poput osvijetljenosti, nepovoljnih klimatskih uvjeta, buke i vibracija. Rad se također bavi procjenom rizika, uključujući matricu procjene rizika i tretman tih rizika. Posljednji dio rada fokusira se na ulogu policije u operacijama spašavanja tijekom katastrofa te planiranje tih operacija.This thesis explores various aspects of police work, with a particular focus on the risks that police officers face while performing their duties. The thesis is divided into several key sections. The first section discusses the different roles within the police force, including traffic, basic, border, and criminal police. The second part analyses workplace risks, both globally and specifically for police officers. It also addresses the physical hazards that officers are exposed to, such as lighting, adverse climatic conditions, noise, and vibrations. The thesis further explores risk assessment, including risk assessment matrices and the treatment of these risks. The final part focuses on the role of the police in rescue operations during disasters and the planning of these operations

Quality control and deformation properties testing of metal materials using modern methods during plastic deformation

U ovom radu provedena su ispitivanja deformacijskih svojstava suvremenim metodama digitalne korelacije slike i termografije te mogućnost korištenja suvremene metode 3D optičkog mjerenja odnosno inspekcije upotrebom automatiziranog mjernog sustava Atos Scanbox na ispitnim uzorcima za statičko vlačno ispitivanje. Dimenzijska i geometrijska kontrola ispitnih uzoraka provedena je usporedbom skeniranog (stvarnog) ispitnog uzorka bakra i njegovog CAD modela. Na ispitnim uzorcima bakra i aluminij-magnezij legure provedeno je određivanje deformacijskih svojstava metodama digitalne korelacije slike i termografije tijekom statičkog vlačnog ispitivanja odnosno plastične deformacije. Utvrđena je mogućnost inspekcije dimenzija i geometrije ispitnih uzoraka 3D optičkim mjerenjima te određivanje i usporedba deformacijskih svojstava dobivenih metodama digitalne korelacije slike i termografije tijekom plastične deformacije bakra i aluminij-magnezij legure. Usporedbom rezultata mjerenja skeniranog ispitnog uzorka bakra i CAD modela utvrđeno je da ne postoje značajna dimenzijska i geometrijska odstupanja. Metodama digitalne korelacije slike i termografije utvrđene su razlike u deformacijskim svojstvima između bakra i aluminij-magnezijeve legure.In this work, tests of deformation properties were carried out using the modern methods of digital image correlation and thermography, as well as the possibility of using modern method of 3D optical measurement, i.e. inspection using the automated measuring system Atos Scanbox on test samples for static tensile testing. The dimensional and geometric control of the test samples was performed by comparing the scanned (actual) test sample of copper and its CAD model. On the test samples of copper and aluminum-magnesium alloy, deformation properties were determined using the methods of digital image correlation and thermography during static tensile test, i.e. plastic deformation. The possibilities of dimensional and geometric inspection of the test samples with 3D optical measurements were determined. The determination and comparison of deformation properties, obtained by the digital image correlation and thermography, during the plastic deformation of copper and aluminum-magnesium alloy were determined. The comparison of the measurement results of the scanned copper test sample and the CAD model showed that there are no significant dimensional and geometric deviations. The differences in deformation properties between copper and aluminum-magnesium alloy were determined using the methods of digital image correlation and thermography

Appearance of Lüders bands in niobium microalloyed steel

Posljednjih godina provode se intenzivna istraživanja nehomogenih deformacija na početku plastičnog toka materijala tijekom hladne deformacije. Prethodna istraživanja pokazala su da postoji razlika u ponašanju mikrolegiranih čelika na početku plastičnog toka s obzirom da kod čelika s dodatkom mikrolegirajućega elementa niobija dolazi do pojave Lüdersovih linija, dok čelici istog osnovnog kemijskog sastava bez dodatka mikrolegirajućega elementa niobija ne pokazuju pojavu nehomogenih deformacija, odnosno pojavu Lüdersovih linija. U ovoj doktorskoj disertaciji provedena su istraživanja na niobijem mikrolegiranom čeliku s različitim dodacima mikrolegirajućega elementa niobija dobivenima u industrijskim i poluindustrijskim uvjetima te niskougljičnom čeliku bez dodatka mikrolegirajućega elementa niobija. Primjenom suvremenih metoda istraživanja termografije i digitalne korelacije slike, zapaženo je da su nehomogene deformacije povezane s pojavom Lüdersovih linija. Statičkim vlačnim ispitivanjem uz suvremene metode, termografiju i digitalnu korelaciju slike te metodama za mikrostrukturna ispitivanja, istražen je utjecaj mikrolegirajućega elementa niobija na pojavu i propagaciju Lüdersovih linija. U svrhu mikrostrukturnih ispitivanja prije i nakon određenog stupnja deformacije korištene su metalografija, pretražna elektronska mikroskopija uz EBSD analizu, transmisijska elektronska mikroskopija te analiza rendgenskom difrakcijom. Posebna pozornost u istraživanju posvećena je formiranju i propagaciji Lüdersovih linija na početku plastičnog toka niobijem mikrolegiranoga čelika tijekom hladne deformacije. U cilju utvrđivanja utjecaja mikrolegirajućega elementa niobija, početne mikrostrukture i brzine deformacije na pojavu i propagaciju Lüdersovih linija te lokalne iznose deformacije provedena su ispitivanja na čelicima različitog kemijskog sastava, početne mikrostrukture i brzine deformacije. S obzirom da je kod niobijem mikrolegiranih čelika prethodnim istraživanjima uočena prisutnost sitnih, deformacijom induciranih, niobijevih precipitata ovim istraživanjem istražen je njihov utjecaj zajedno s dislokacijama na formiranje i propagaciju Lüdersove linije u različitim pozicijama zone deformacije kako bi se utvrdio njihov mehanizam nastajanja. Istraživanja su pokazala da utjecajni faktori različitog sadržaja mikrolegirajućega elementa niobija, početna mikrostruktura i brzina deformacije imaju utjecaj na propagaciju Lüdersove linije. Međutim, brzina deformacije nema utjecaj na pojavu Lüdersove linije dok dodatak mikrolegirajućega elementa niobija, početna mikrostruktura te veličina i sastav niobijevih precipitata imaju utjecaj na pojavu Lüdersove linije. Sitni, deformacijom inducirani, niobijevi precipitati i gustoća dislokacija pokazali su se kao parametri koji imaju značajan utjecaj na nastajanje i propagaciju Lüdersove linije. Detaljno je, po prvi puta, postavljen mehanizam formiranja i propagacije Lüdersove linije kod niobijem mikrolegiranoga čelika. Na kraju su postavljeni jednostavni matematički modeli za opisivanje utjecajnih parametara na formiranje i propagaciju Lüdersove linije. Postavljenim matematičkim modelima moguće je predvidjeti ponašanje niobijem mikrolegiranoga čelika s obzirom na pojavu Lüdersove linije na početku plastičnog toka tijekom hladne deformacije.Intensive research into inhomogeneous deformations at the start of the plastic flow in cold deformation of different metal materials has been carried out during the last few years. Previous research has clearly shown that there are differences in deformation behaviour of microalloyed steels at the start of the plastic flow. Lüders bands appear only in low carbon steels with addition of microalloying element niobium while low carbon steels with the same basic chemical composition without niobium do not show inhomogeneous deformations, i.e. Lüders bands. This research was carried out on low carbon steels without niobium and niobium microalloyed steels with various additions of the microalloying element niobium obtained in industrial and semi-industrial conditions. Connection of Lüders bands with inhomogeneous deformations was observed using modern methods of thermography and digital image correlation. Influence of microalloying element niobium on Lüders bands formation and propagation was researched by static tensile tests with thermography and digital image correlation, and modern methods of microstructural testing. Metallography, scanning electron microscopy with EBSD analysis, transmission electron microscopy and X-ray diffraction analysis were used for the purpose of microstructural testing before and after a certain deformation degree. In this research particular attention was given to the formation and propagation of Lüders bands at the start of the plastic flow of niobium microalloyed steels during cold deformation. Tests were conducted on steels with various chemical composition, initial microstructure and strain rate in order to determine the influence of the microalloying element niobium, the initial microstructure and strain rate on the appearance and propagation of Lüders bands as well as local strain amounts. Previous studies have shown a presence of fine deformation induced niobium precipitates in niobium microalloyed steels. This doctoral thesis presents a research of their influence along with dislocations on the formation and propagation of Lüders bands in various positions of the deformation zone to determine the mechanism of Lüders bands formation. The research showed an influence of various contents of the microalloying element niobium, initial microstructure and strain rate on the propagation of the Lüders bands. However, the strain rate do not have influence on the appearance of Lüders bands while the addition of the microalloying element niobium, initial microstructure, size and chemical composition of niobium precipitates have influence on the appearance of Lüders bands. Fine deformation induced niobium precipitates and dislocation density showed a significant impact on the formation and propagation of Lüders bands. The mechanism of formation and propagation of Lüders bands in niobium microalloyed steel is set out in detail for the first time. Simple mathematical models for the parameters influencing the formation and propagation of Lüders bands were developed at the end of the doctoral thesis. Behaviour of niobium microalloyed steels with Lüders bands can be predicted by the defined mathematical models at the start of the plastic flow during the cold deformation

Firefighting Tactis Using Drones

Upotreba bespilotnih letjelica (dronova) u vatrogastvu postaje sve češća praksa u modernim sustavima civilne zaštite. Njihova primjena donosi brojne prednosti, osobito u fazama izviđanja, nadzora i taktičkog planiranja prilikom gašenja požara. Ovaj diplomski rad bavi se analizom taktičkih mogućnosti koje dronovi omogućuju prilikom požarnih intervencija, s naglaskom na njihove operativne prednosti, tehničke karakteristike i integraciju u postojeće vatrogasne protokole. Dronovi omogućuju brz uvid u stanje na terenu bez izravnog izlaganja vatrogasaca riziku. Pomoću kamera visoke rezolucije, termovizijskih sustava i GPS praćenja, moguće je u stvarnom vremenu pratiti širenje požara, detektirati žarišta, identificirati ugrožene objekte i osobe, te usmjeravati vatrogasne snage na najkritičnija mjesta. Osim toga, dronovi se mogu koristiti i za dostavu lakšeg vatrogasnog materijala ili komunikaciju u područjima bez signala. U praktičnom dijelu rada provedena je vježba u suradnji s Vatrogasnom zajednicom grada Siska, uključujući DVD Sela i DVD „Mladost“ Sisak, u kojoj je testirana upotreba drona tijekom simulacije požara na otvorenom prostoru. Dron je korišten za izviđanje terena, nadzor kretanja vatre te za navođenje vatrogasaca i vozila. Rezultati vježbe pokazali su značajno poboljšanje u brzini donošenja odluka i učinkovitosti gašenja požara, uz istovremeno smanjenje izloženosti vatrogasaca opasnim uvjetima. Zaključno, integracija dronova u vatrogasne taktike ne predstavlja zamjenu za ljude, već dodatni alat koji unapređuje sigurnost i operativnost. Nastavak razvoja ove tehnologije te edukacija vatrogasnog osoblja u njenoj primjeni ključni su za daljnji napredak vatrogasnog sustava.The use of unmanned aerial vehicles (drones) in firefighting has become an increasingly common practice in modern civil protection systems. Their implementation brings numerous advantages, particularly in the stages of reconnaissance, monitoring, and tactical planning during fire suppression operations. This thesis explores the tactical possibilities enabled by drones in firefighting interventions, with an emphasis on their operational benefits, technical features, and integration into existing firefighting protocols. Drones provide a rapid overview of the situation on the ground without exposing firefighters to direct risk. Through the use of high-resolution cameras, thermal imaging systems, and GPS tracking, it is possible to monitor fire spread in real time, detect hotspots, identify endangered objects and individuals, and direct firefighting forces to the most critical locations. Additionally, drones can be used to deliver lightweight firefighting materials or maintain communication in areas without signal coverage. As part of the practical segment of this research, an exercise was conducted in cooperation with the Firefighting Association of the City of Sisak, including the volunteer fire brigades DVD Sela and DVD "Mladost" Sisak. The exercise tested the use of a drone during a simulated wildfire in an open area. The drone was utilized for terrain reconnaissance, fire movement monitoring, and guiding firefighters and vehicles. The results of the exercise showed a significant improvement in decision-making speed and firefighting efficiency, while simultaneously reducing firefighter exposure to hazardous conditions. In conclusion, the integration of drones into firefighting tactics does not replace human personnel but serves as an additional tool that enhances safety and operational performance. Continued development of this technology and the education of firefighting personnel in its application are crucial for the further advancement of the firefighting system

Development, application and impact of lighting on workers' health and working environment

Ovaj rad istražuje razvoj, primjenu i utjecaj rasvjete na zdravlje radnika i radni okoliš, s posebnim naglaskom na važnost pravilnog osvjetljenja u radnim prostorima. Rasvjeta je ključan čimbenik radnog okruženja jer izravno utječe na vid, koncentraciju, produktivnost i opće psihofizičko stanje radnika. Povijesni pregled obuhvaća prirodne izvore svjetlosti, poput Sunčeve svjetlosti i vatre, te razvoj umjetne rasvjete, od žarulja sa žarnom niti, fluorescentnih svjetiljki i halogenih izvora, do modernih LED tehnologija i pametnih sustava rasvjete. Rad analizira fotometrijske veličine, uključujući intenzitet svjetlosti, rasvijetljenost i iluminanciju, te objašnjava njihovu primjenu pri projektiranju unutarnjih i vanjskih rasvjetnih sustava. Istražuje kako pravilno projektirana unutarnja rasvjeta može smanjiti umor, povećati koncentraciju te smanjiti rizik od ozljeda i nesreća na radu. Vanjska rasvjeta, posebice u kontekstu cestovne i javne rasvjete, također je obuhvaćena, uz razmatranje noviteta poput pametnih sustava koji omogućuju optimizaciju potrošnje energije, smanjenje svjetlosnog onečišćenja i povećanje sigurnosti u javnim prostorima. Svjetlosno onečišćenje predstavlja značajan problem, ne samo za okoliš, već i za ljudsko zdravlje, stoga je u ovom radu analizirana regulativa koja se odnosi na kontrolu svjetlosnog onečišćenja i pravilnu primjenu rasvjete. Osim analize rasvjetnih tehnologija, rad obrađuje metode ispitivanja rasvjete, korištenje mjernih uređaja te zakonske propise koji određuju minimalne standarde osvjetljenja. Predložene su mjere zaštite od prekomjerne i nedovoljne osvijetljenosti kako bi se osigurali sigurni i zdravi uvjeti rada.This paper explores the development, application, and impact of lighting on workers' health and the working environment, with a particular emphasis on the importance of proper illumination in workplaces. Lighting is a crucial factor in the work environment as it directly affects vision, concentration, productivity, and the overall psychophysical condition of workers. The historical overview includes natural light sources, such as sunlight and fire, as well as the development of artificial lighting, from incandescent bulbs, fluorescent lamps, and halogen sources to modern LED technologies and smart lighting systems. The paper analyzes photometric quantities, including light intensity, illuminance, and illumination, and explains their application in designing indoor and outdoor lighting systems. It investigates how well-designed indoor lighting can reduce fatigue, enhance concentration, and lower the risk of workplace injuries and accidents. Outdoor lighting, particularly in the context of road and public lighting, is also addressed, along with innovations such as smart systems that optimize energy consumption, reduce light pollution, and enhance public safety. Light pollution represents a significant issue, not only for the environment but also for human health. Therefore, this paper examines regulations related to light pollution control and the proper application of lighting. In addition to analyzing lighting technologies, the paper discusses lighting assessment methods, the use of measuring instruments, and legal regulations that define minimum lighting standards. Protective measures against excessive and insufficient illumination are proposed to ensure safe and healthy working conditions

Development and application of immobilized composite photocatalysts obtained by sol-gel process

U ovom radu korišten je fotokatalizator titan(IV) oksid (TiO2) zbog svoje dostupnosti, kemijske i biološke inertnosti, ali i dobrih fotokatalitičkih svojstava. Da bi se olakšala njegova primjena u usporedbi sa suspendiranim oblikom provedena je njegova imobilizacija na mrežu od staklenih vlakana sol-gel postupkom. Istraživano je mogu li se u procesu sušenja primijeniti i mikrovalovi zbog same brzine sušenja i pripreme fotokatalizatora te je utvrđen negativan utjecaj. Daljnje istraživanje bilo je usmjereno prema dopiranju TiO2 višeslojnim ugljičnim nanocijevima (MWCNT) i grafen oksidom (GO) s ciljem poboljšanja fotokatlitičke aktivnosti TiO2 pri Sunčevom zračenju. Dopiranje je provedeno s različitim udjelima MWCNT u odnosu na masu TiO2: 1,5, 5, 10, 25, 50 i 100 mas. %. Najbolju fotokatalitičku aktivnost pokazao je fotokatalizator dopiran s 10 mas.% MWCNT u usporedbi s pripravljenim TiO2 fotokatalizatorom. Na temelju istraživanja fotokatalizatora pripremljenog s MWCNT pripremljeni su i fotokatalizatori dopirani s GO i to u udjelima od 5, 10 i 25 mas. %. Rezultati su pokazali da GO negativno utječe na fotokatalizu. Fotokatalitička aktivnost pripremljenih fotokatalizatora je praćena razgradnjom modalne otopine salicilne kiseline UV-Vis spektrofotometrom pod simuliranim Sunčevim zračenjem. Salicilna kiselina je korištena kao primjer mikroonečišćenja koje se uvelike pojavljuje u okolišu jer ima široku primjenu u lijekovima i kozmetičkim proizvodima. Nadalje, istražena je postojanost pripravljenih fotokatalizatora te su rezultati starenja na zraku i u vodi pokazali da je moguća višekratna uporaba pripremljenih fotokatalizatora bez značajnog opadanja njegove aktivnosti.It was investigated whether microwaves could also be used for the drying process due to the speed of drying and the preparation of the photocatalyst, and a negative impact was determined. Further research was focused on the doping of titanium(IV) oxide (TiO2) with multi wall carbon nanotubes (MWCNT) and graphene oxide (GO) with the aim of improving the photocatalytic activity of TiO2 under solar radiation. The doping was carried out with different proportions of MWCNT in relation to the mass of the TiO2: 1.5, 5, 10, 25, 50 and 100 wt. %. The photocatalyst doped with 10 wt. % MWCNT showed the best photocatalytic activity compared to the photocatalyst prepared with TiO2. Based on the study of the photocatalyst prepared with MWCNT, photocatalysts doped with GO were also prepared in proportions of 5, 10 and 25 wt. %. The results showed that GO has a negative effect on the photocatalysis. The photocatalytic activity of the prepared photocatalysts was monitored by decomposing the salicylic acid modal solution with a UV-Vis spectrophotometer under simulated solar radiation. Salicylic acid was used as an example of a micropollutant that is widely present in the environment as it is often used in pharmaceuticals and cosmetic products. Furthermore, the stability of the prepared photocatalysts was investigated, and the results of aging in air and in water showed that repeated use of the prepared photocatalysts is possible without a significant decrease in its activity

Hazards, harmfulness and efforts at hte workplace of workers in the retail sale of cosmetics and toiletries

Ovaj završni rad bavi se analizom opasnosti, štetnosti i napora kojima su izloženi radnici zaposleni u trgovini na malo kozmetičkim i toaletnim proizvodima. Maloprodajni sektor, osobito u segmentu kozmetike, karakterizira izloženost različitim rizicima – od fizičkih i kemijskih štetnosti do psihosocijalnih opterećenja. Kroz rad se prikazuju najčešći izvori profesionalnih opasnosti kao što su dugotrajno stajanje, nepravilna ergonomija radnog mjesta, kontakt s kemikalijama prisutnima u kozmetičkim proizvodima te učestali stres i komunikacija s klijentima. Rad također obrađuje pravne aspekte zaštite na radu, kao i primjere dobre prakse u cilju unapređenja radnog okruženja. Na temelju analize stručne literature i postojećih radnih uvjeta, predložene su mjere za poboljšanje zaštite zdravlja i sigurnosti zaposlenih, s naglaskom na prevenciju štetnih utjecaja i promicanje ergonomskih i higijenskih standarda na radnom mjestu.This thesis analyzes the hazards, harmful effects, and efforts encountered by workers in the retail sector of cosmetic and toiletry products. The cosmetic retail environment exposes employees to various occupational risks – including physical and chemical hazards, as well as psychosocial challenges. The paper highlights common risk factors such as prolonged standing, improper workplace ergonomics, exposure to chemicals found in cosmetic products, and the stress associated with constant customer interaction. It also explores legal frameworks for occupational safety, as well as examples of best practices aimed at improving workplace conditions. Based on an analysis of professional literature and current working conditions, the paper presents recommendations to enhance employee health and safety, focusing on the prevention of harmful exposure and the promotion of ergonomic and hygienic standards in the workplace