Repository of Josip Juraj Strossmayer University of Osijek
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Calculation of inner forces for a three - hinged frame and projections of velocity
No full textZavršni rad se sastoji od dva dijela: Sveučilište Josipa Jurja Strossmayera u Osijeku Građevinski i arhitektonski fakultet Osijek Prvi dio zadatka odnosi se na izračun unutrašnjih sila u presjeku n-n pod djelovanjem zadanog opterećenja na trozglobni okvir. Za proračun unutrašnjih sila koriste se dvije metode: klasični postupak iz uvjeta ravnoteže i metoda virtualnog rada. Proraču obuhvaća momente savijanja, poprečne i uzdužne sile. Drugi dio zadatka odnosi se na odrađivanje kuteva zaokreta zadanih tijela, te pomake zadanih točaka. Kutem zaokreta koji nam je zadan određujemo kinematske veličine preostalih tijela u konstrukciji. Izračun se vrši pomoću planova pomaka, odnosno određivanja polova pomaka, crtanja poznatih kinematskih veličina jednog tijela, konstruiranja plana pomaka preostalog dijela mehanizma i određivanje kinematskih veličina svih tijela iz geometrijskih uvjeta. Rezultati se kontroliraju vektorskim računom.The final thesis is divided into two main parts: The first part focuses on the analysis of internal forces at the cross-section n-n resulting from the applied load on a three-hinged frame. The internal force analysis is carried out using two methods: the classical method based on the conditions of static equilibrium, and the method of virtual work. The analysis includes the calculation of bending moments, shear forces, and axial (normal) forces. The second part of the thesis is dedicated to the determination of rotation angles of specified bodies and the displacement of selected points within the structure. Based on a given rotation angle, the kinematic parameters of the remaining structural elements are determined. The calculation is performed using displacement diagrams, which involve identifying displacement poles, graphically representing known kinematic quantities of one body, constructing the displacement diagram for the remaining parts of the mechanism, and determining the kinematic parameters of all structural elements based on geometric constraints. The final results are verified using vector analysis
The frequency of apicoectomy in a specialist office for oral surgery practice
No full textCilj istraživanja: Cilj istraživanja bio je analizirati kliničke i epidemiološke značajke apikotomije te ispitati odnose između demografskih i anatomskih varijabli (spol, dob, lokalizacija, kvadrant, FDI-oznaka, broj zahvata)
Nacrt studije: Istraživanje je oblikovano kao retrospektivna presječna studija, provedena analizom podataka iz kartona pacijenata koji su tijekom trogodišnjeg razdoblja bili podvrgnuti apikotomiji u specijalističkoj stomatološkoj ordinaciji.
Materijal i metode: Analizirani su podatci o 69 pacijenata i ukupno 85 apikotomiranih zuba. Varijable uključene u analizu bile su dob, spol, lokalizacija zahvata (gornja/donja čeljust), kvadrant, FDI-oznaka zuba i broj apikotomija po ispitaniku. Korištene su deskriptivne metode i inferencijalna statistika (hi-kvadrat test, Mann–Whitneyev U test, Spearmanova korelacija).
Rezultati: Apikotomija je najčešće izvođena kod osoba srednje životne dobi (prosjek 46,59 godina), s blagom dominacijom muškog spola (55,1 %). Najčešće je izvođena u gornjoj čeljusti (89,9 %), nešto češće u drugom kvadrantu (45,9 %). Najčešće apikotomirani zubi bili su zubi 21, 12 i 22. Većina pacijenata imala je jednu apikotomiju (79,7 %). Analiza nije pokazala značajne povezanosti između spola i lokalizacije zahvata, kao ni između dobi i lokalizacije, te spola, dobi ili kvadranta i broja zahvata. Nadalje, lokalizacija apikotomiranog zuba prema FDI-sustavu nije bila značajno povezana s demografskim karakteristikama pacijenata.
Zaključak: Dobiveni nalazi upućuju na to da se apikotomija najčešće primjenjuje u području gornje čeljusti, osobito na prednjim zubima. Izostanak statistički značajnih povezanosti između ispitivanih varijabli potvrđuje da je riječ o individualiziranoj terapijskoj odluci, vođenoj kliničkom procjenom.Objective: This study aimed to analyze the clinical and epidemiological characteristics of apicoectomy procedures and to examine the relationships between demographic and anatomical variables (sex, age, localization, quadrant, FDI tooth notation, and number of procedures).
Study Design: This research was a retrospective cross-sectional study conducted by analyzing patient records from a specialist dental surgery clinic over three years.
Materials and Methods: Data from 69 patients and 85 apicoectomized teeth were analyzed. Variables included age, sex, surgical site localization (maxilla/mandible), quadrant, FDI tooth notation, and the number of apicoectomies per patient. Descriptive methods and inferential statistical analyses were used (chi-square test, Mann–Whitney U test, Spearman correlation).
Results: Apicoectomy was most commonly performed in middle-aged individuals (mean age 46.59 years), with a slight male predominance (55.1%). The procedure was most frequently carried out in the maxilla (89.9%), especially in the second quadrant (45.9%). The most commonly treated teeth were 21, 12, and 22. Most patients underwent a single apicoectomy (79.7%). The analysis showed no statistically significant associations between sex and localization, between age and localization, or between sex, age, or quadrant and the number of apicoectomies. Additionally, the localization of the apicoectomized tooth according to FDI notation was not significantly associated with patients’ demographic characteristics.
Conclusion: The findings indicate that apicoectomy is most commonly performed in the maxilla, particularly on anterior teeth. The absence of a statistically significant correlation between the analyzed variables supports the interpretation of apicoectomy as an individualized, clinically guided intervention
The impact of stress on the quality of life of nurses and medical technicians
No full textCILJ ISTRAŽIVANJA: Ispitati utjecaj stresa na kvalitetu života medicinskih sestara i tehničara.
USTROJ STUDIJE: Provedeno je presječno istraživanje.
ISPITANICI I METODE: Ispitanike je činilo 216 hrvatskih medicinskih sestara i tehničara s više od pet godina radnog staža u struci. Podatci su prikupljani Upitnikom o utjecaju stresa na kvalitetu života medicinskih sestara i tehničara.
REZULTATI: Većinu su činile žene, ispitanici s 45 i manje godina, u bračnoj/izvanbračnoj zajednici, s preddiplomskim studijem te mjestom življenja u gradu. Većina je bila zaposlena u primarnoj i sekundarnoj zdravstvenoj zaštiti, s 22 i manje godina radnog staža te nije bolovala od profesionalnih bolesti ni ozljeda na radu. Kod većine je bila prisutna umjerena razina stresa. Ispitanici su iskazali dobru kvalitetu života, iskazali su značajno niže opće zdravlje u usporedbi s općom kvalitetom života, fizičkim zdravljem i društvenim odnosima. Loša kvaliteta života bila je značajno učestalija u ispitanika s visokom razinom stresa. Visoka je razina stresa bila značajno učestalija u ispitanika u dobi 45 i manje godina, u onih koji žive na selu, u usporedbi s onima koji žive u gradu te u ispitanika s 22 i manje godina radnog staža. Loša je kvaliteta života bila značajno učestalija u ispitanika zaposlenih u sekundarnoj i tercijarnoj u usporedbi sa zaposlenima u primarnoj zdravstvenoj zaštiti.
ZAKLJUČAK: Želi li društvo kvalitetnu sestrinsku skrb, mora ulagati u smanjenje stresa u sestrinskoj profesiji i poboljšanje kvalitete života medicinskih sestara i tehničara. Samo otporne sestre odlične kvalitete života mogu pružati kvalitetnu sestrinsku skrb.OBJECTIVES: To examine the impact of stress on the quality of life of nurses and medical technicians.
STUDY DESIGN: A cross-sectional survey was conducted.
PARTICIPANTS AND METHODS: The respondents were 216 Croatian nurses and medical technicians with more than five years of experience in the profession. Data were collected using the Questionnaire on the Impact of Stress on the Quality of Life of Nurses and Medical Technicians.
RESULTS: The majority of respondents were women, aged 45 and under, in a married/cohabiting relationship, with undergraduate qualifications and living in the city. The majority were employed in primary and secondary healthcare, with 22 or less years of work experience and did not suffer from occupational diseases or injuries at work. Most had a moderate level of stress. The respondents reported a good quality of life, but reported significantly lower general health compared to general quality of life, physical health and social relationships. Lower quality of life was significantly more common in respondents with a high level of stress. High levels of stress were significantly more common in respondents aged 45 and under, those living in rural areas compared to those living in cities and in respondents with 22 or less years of work experience. Lower quality of life was significantly more common in respondents employed in secondary and tertiary healthcare compared to those employed in primary healthcare.
CONCLUSION: If society wants good quality nursing care, it must invest in reducing stress in the nursing profession and improving the quality of life of nurses and technicians. Only resilient nurses with an excellent quality of life can provide good quality nursing care
Students' Perception of Family Roles and Values of Traditional and Contemporary Families
No full textObitelj predstavlja temeljnu društvenu zajednicu koja se kroz povijest mijenjala pod utjecajem društvenih, kulturnih i ekononskih promjena. Tradicionalne obitelji, koje uključuju nuklearnu i proširenu obitelj, nadopunjuju ili čak zamjenjuju suvremeni oblici u koje se ubrajaju izvanbračne zajednice, obitelji bez djece, jednoroditeljske, istospolne te udomiteljske i posvojiteljske obitelji. Nove obiteljske strukture donose drukčije vrijednosti i uloge članova u odnosu na tradicionalni oblik te postaju sve prisutnije u različitim društvima. Suvremeni ili alternativni oblici predstavljaju transformaciju tradicionalnog poimanja obitelji, pri čemu pojedinci oblikuju vlastite, pozitivne ili negativne stavove koji izravno utječu na opću percepciju i prihvaćanje članova u široj društvenoj okolini. Cilj istraživanja ovog rada bio je ispitati razlike u percepciji studenata i studentica prema obiteljskim vrijednostima i različitim ulogama članova unutar tradicionalnih i suvremenih obitelji, s obzirom na određene sociodemografske varijable. Posebna pažnja posvećena je razlikama u stavovima prema roditeljskim, partnerskim i rodnim ulogama, kao i utjecaju spola, studijskog programa, oblika obitelji i mjesta odrastanja na formiranje stih stavova. Provedbom analiza utvrđene su statistički značajne razlike u stavovima studenata i studentica prema suvremenim oblicima obitelji i tradicionalnim rodnim ulogama, s obzirom na spol, studijski program i mjesto odrastanja, dok oblik obitelji za vrijeme odrastanja nije pokazao statistički značajnu razliku. Uočena niža stopa tolerancije prema suvremenim oblicima obitelji i sklonost tradicionalnim rodnim ulogama kod muških ispitanika ukazuje na potrebu za obrazovnim sadržajima koji promiču razumijevanje i prihvaćanje različitih obiteljskih struktura.The family represents a fundamental social unit that has historically evolved under the influence of social, cultural, and economic changes. Traditional family structures, including nuclear and extended families, are increasingly being complemented or even replaced by contemporary forms such as cohabiting partnerships, childless families, single-parent families, same-sex families, as well as foster and adoptive families. These new family structures bring different values and member roles compared to the traditional type and are becoming more prevalent across various societies. Contemporary or alternative family forms represent a transformation of the traditional understanding of family, wherein individuals form their own positive or negative attitudes, which directly influence the general perception and social acceptance of family members within the broader community. The aim of this research was to examine the differences in perceptions among male and female students regarding family values and the roles of family members within both traditional and contemporary families, considering selected sociodemographic variables. Particular attention was given to attitudes toward parental, partnership, and gender roles, as well as the influence of gender, study program, family structure, and place of upbringing on the formation of these attitudes. The analysis revealed statistically significant differences in students’ attitudes toward contemporary family forms and traditional gender roles based on gender, study program, and place of upbringing, whereas the family structure during childhood did not show a statistically significant difference. The observed lower level of tolerance toward contemporary family forms and a stronger inclination toward traditional gender roles among male respondents indicate the need for educational content that fosters understanding and acceptance of diverse family structures
Automation of enzyme dosing system in the brewing industry
No full textOvaj diplomski rad prikazuje razvoj i simulaciju automatiziranog sustava za doziranje
enzima u procesu proizvodnje piva. Korištenjem softverskih alata TIA Portal i BRAUMAT implementiraju
se sekvence koje upravljaju radom spremnika, dozirnih linija i pripadajućih procesnih jedinica. Sustav
uključuje provjeru svih sigurnosnih i tehnoloških uvjeta potrebnih za stabilan rad, uz vizualizaciju procesa
u SCADA sučelju. Osim osnovne strukture sustava, detaljno se analiziraju razlike u načinu doziranja
enzima Thermamyl, Ultraflo, Ceremix i Attenuzyme, u skladu s njihovim tehnološkim zahtjevima.
Simulacija se izvodi u realnom vremenu, što omogućuje testiranje funkcionalnosti bez potrebe za
fizičkom opremom. Razvijeni model prilagođen je stvarnim industrijskim uvjetima i spreman za primjenu
u pogonu.This thesis presents the development and simulation of an automated enzyme dosing system
in the beer production process. Using TIA Portal and BRAUMAT software tools, sequences are
implemented to control the operation of enzyme tanks, dosing lines, and associated process units. The
system includes verification of all safety and technological conditions required for stable operation,
along with process visualization in the SCADA interface. In addition to the general system structure, the
work provides a detailed analysis of the differences in dosing methods for Thermamyl, Ultraflo, Ceremix,
and Attenuzyme, according to their specific technological requirements. The simulation is performed in
real time, allowing functionality testing without the need for physical equipment. The developed model
is adapted to real industrial conditions and ready for practical implementation
Perception of fair trade among consumers : Graduate paper
No full textOvaj diplomski rad istražuje percepciju pravedne trgovine među potrošačima u Hrvatskoj. Rad se fokusira na analizu svijesti potrošača o Fairtrade oznaci, motivatore i barijere za kupnju Fairtrade proizvoda te percepciju vjerodostojnosti oznake. Cilj rada je pridonijeti boljem razumijevanju ponašanja potrošača prema pravednoj trgovini i pružiti smjernice za razvoj učinkovitijih strategija za promociju etičke potrošnje. U istraživanju je korišten kvantitativni pristup, a podaci su prikupljeni anketnim upitnikom na uzorku od 107 ispitanika. Rezultati istraživanja ukazuju na nedovoljnu prepoznatljivost Fairtrade oznake među potrošačima, ističu etičke motive kao glavni motivator za kupnju, ali i ukazuju na višu cijenu i nedovoljnu dostupnost proizvoda kao značajne barijere.
Također, značajan udio ispitanika izražava sumnju u vjerodostojnost oznake. Na temelju provedenog istraživanja, dobiveni podaci imaju značajne implikacije za marketinške i komunikacijske strategije organizacija koje promoviraju pravednu trgovinu.This graduate thesis explores consumer perception of fair trade in Croatia. The thesis focuses on analyzing consumer awareness of the Fairtrade label, motivators and barriers to purchasing Fairtrade products, and the perception of the label's credibility. The aim of the thesis is to contribute to a better understanding of consumer behavior towards fair trade and to provide guidelines for developing more effective strategies for promoting ethical consumption. A quantitative approach was used in the research, and data was collected through a questionnaire from a sample of 107 respondents. The research results indicate insufficient recognition of the Fairtrade label among consumers, highlight ethical motives as the main motivator for purchase, but also point to higher prices and insufficient product availability as significant barriers.
Additionally, a significant portion of respondents express doubt in the label's credibility. These findings have important implications for the marketing and communication strategies of organizations that promote fair trade
Monetizing Digital Influence: The Role and Challenges of Influencers in Shaping Business Models : Final paper
No full textU ovom završnom radu istražena je uloga influencera u suvremenom digitalnom ekosustavu, s
posebnim naglaskom na njihove poslovne modele i strategije monetizacije. Influenceri su danas
mnogo više od promotora proizvoda, oni su kreatori vrijednosti, poduzetnici koji razvijaju
vlastite brendove, lansiraju proizvode i usluge te oblikuju trendove i ponašanje potrošača. Ovaj
rad analizira glavne izvore prihoda influencera, koji se odnose na sponzorirane objave, affiliate
marketing, prodaju vlastitih proizvoda, pretplate te pružanje edukacija i konzultantskih usluga.
Posebna pozornost posvećena je razlikama među platformama kao što su YouTube, Instagram
i TikTok, koje zahtijevaju različite formate sadržaja i komunikacijske strategije. Istraživanje
ukazuje na to da je vjerodostojnost ključan faktor uspješne monetizacije, kao i sposobnost
prilagodbe promjenama algoritama, tržišnim uvjetima i očekivanjima publike. Uz to, rad ističe
izazove poput zasićenosti tržišta, očuvanja autentičnosti te etičkih i pravnih dilema. Zaključno,
influenceri predstavljaju važan segment digitalnog marketinga i ekonomije kreatora, a njihova
će se uloga u budućnosti dodatno profesionalizirati i sve više integrirati u poslovne modele
digitalne ekonomije.This thesis explores the role of influencers in the contemporary digital ecosystem, with a
particular focus on their business models and monetization strategies. Influencers today are
much more than product promoters—they are value creators and entrepreneurs who develop
personal brands, launch products and services, and shape consumer trends and behavior. The
paper analyzes the main sources of influencer income, including sponsored posts, affiliate
marketing, direct product sales, subscription models, and the provision of educational and
consulting services. Special attention is given to the differences between platforms such as
YouTube, Instagram, and TikTok, each requiring distinct content formats and communication
strategies. The research highlights that credibility is a key factor in successful monetization,
along with the ability to adapt to changes in algorithms, market dynamics, and audience
expectations. Additionally, the paper outlines challenges such as market saturation, maintaining
authenticity, and navigating ethical and legal issues. In conclusion, influencers represent a
significant segment of digital marketing and the creator economy, and their role is expected to
become increasingly professionalized and integrated into broader business models within the
digital economy
Quality of life analysis in Croatia : Graduate paper
No full textCilj ovog rada bio je ispitati kvalitetu života kod stanovnika RH. Rad je podijeljen na teorijski
i istraživački dio. U drugom poglavlju, teorijskom dijelu rada, nastojalo se je teorijski objasniti
razliku između objektivnih i subjektivnih pokazatelja kvalitete života, povijesnu evoluciju
istraživanja kvalitete života od ekonomskog pristupa do uključivanja socijalne i psihološke
dimenzije te izazove koje donosi sve veći tehnološki napredak ali i integracija umjetne
inteligencije u sve sfere kako poslovanja, tako i ukupnog života. U trećem i četvrtom poglavlju
rada učinila se analiza prethodnih istraživanja kvalitete života; u EU-u i RH, nakon čega su se,
u petom poglavlju, analizirali rezultati istraživanja ovog rada. U istom poglavlju donesena je
usporedba prethodnih rezultata sa rezultatima provedenog istraživanja, ali i dokazivanje
hipoteza koje su u uvodnom dijelu postavljene. Šesto poglavlje donosi zaključak cijelog rada.
Rezultati ovog istraživanja sugeriraju kako je subjektivna percepcija kvalitete života u RH na
srednjoj razini (prosječna ocjena svih ispitanika iznosi 3.02). Također, uočena je vrlo niska
razina zadovoljstva političkom situacijom, zdravstvenim sustavom, brzinom zapošljavanja, kao
i mogućnošću stambenog zbrinjavanja.
Nešto veće zadovoljstvo ispitanici su iskazali po pitanju sigurnosti u zemlji te društvenog života
i pripadanja zajednici.
Hipotezama se je nastojalo utvrditi povezanost između nekih ekonomskih i demografskih
obilježja ispitanika sa njihovom percepcijom kvalitete života.
Uočene su razlike između poimanja kvalitete vlastitog života po pitanju spola, razine
obrazovanja i dobi. Rezultati pokazuju kako su subjektivno kvalitetom života zadovoljnije
osobe muškog spola, osobe iz kućanstava sa višim primanjima te osobe koje su zaposlene.The aim of this paper was to examine the quality of life among residents of the Republic of
Croatia. The paper is divided into theoretical and research sections. The second chapter, the
theoretical part, attempts to explain the difference between objective and subjective indicators
of quality of life, the historical evolution of quality of life research – from an economic
approach to the inclusion of social and psychological dimensions,as well as the challenges
posed by increasing technological advancement and the integration of artificial intelligence into
all spheres of business and everyday life. The third and fourth chapters provide an analysis of
previous quality of life studies in both the EU and Croatia. This is followed, in the fifth chapter,
by an analysis of the results of the present research. In the same chapter, a comparison is made
between previous findings and the results of the current study, alongside the testing of the
hypotheses set out in the introduction. The sixth chapter concludes the paper.
The results of this research suggest that the subjective perception of quality of life in Croatia is
at a moderate level (the average rating of all respondents is 3.02). A particularly low level of
satisfaction was recorded with regard to the political situation, the healthcare system,
employment opportunities, and access to housing.
Slightly higher levels of satisfaction were observed in relation to national safety, social life, and
the sense of community belonging.
The hypotheses aimed to examine the correlation between certain economic and demographic
characteristics of respondents and their perception of quality of life.
Notable differences were observed in how individuals perceive their own quality of life
depending on gender, education level, and age. The results indicate that men, individuals from
households with higher incomes, and employed persons report higher subjective satisfaction
with their quality of life
BIOGAS PRODUCTION PROCESS FROM FOOD INDUSTRY WASTE STREAMS
No full textIndustrija proizvodnje čipsa, flipsa i drugih snack proizvoda proizvodi značajnu količinu otpada tijekom svog proizvodnog procesa, koji uključuje otpad nastao pripremom sirovina i tijekom tehnoloških faza proizvodnje. Cilj ovog rada bio je istražiti otpadne tokove bogate organskim tvarima u industriji proizvodnje čipsa, flipsa i drugih snack proizvoda, te analizirati njihov potencijal za anaerobnu obradu i proizvodnju bioplina. Također, rad se fokusira na procjenu prinosa bioplina, izraženog kroz bioplinski i biometanski potencijal, temeljen na biorazgradivim količinama otpada koji nastaju u promatranoj industriji.
Nakon provedenih laboratorijskih ispitivanja suhe tvari, vlage, hlapljive tvari i pepela kod ispitivanih otpadnih tokova, najveći udio suhe tvari zabilježen je u uzorku otpadnog čipsa, (98,45%). Neznatno manji udio suhe tvari zabilježen je u uzorku mješavine flipsa/kokičara/kokičara neispucanog/rice snacka. Najveći udio hlapljive tvari opažen je u uzorcima otpadnog ulja suncokret/palma, 99,99%, a najmanji udio hlapljive tvari opažen je u uzorku iz škrobne taložnice gdje je ista iznosila 75,64%. Najmanji udio pepela imao je uzorak ulja suncokret/palma dok je uzorak iz škrobne taložnice imao najveći udio pepela. Sve vrijednosti KPK također ukazuju, da su supstrati povoljni za proizvodnju bioplina. Kod ispitivanja bioplinskog i biometanskog potencijala, udjela metana te biorazgradljivosti, uočen je najniži bioplinski potencijal kod uzorka iz škrobne taložnice, 359 NL/kg s.tv. Uzorak iz škrobne taložnice ima i najniži biometanski potencijal od 228 NL/kg s.tv. te biorazgradljivost od 42,0%. Dobiveni rezultati u skladu su s očekivanim s obzirom na to da od svih ispitivanih uzoraka, uzorak iz škrobne taložnice ima najmanji udio hlapljive (organske) tvari zbog čega je i biorazgradljivost posljedično najmanja u odnosu na ostale promatrane uzorke. Najveća biorazgradljivost uočena je za škrob i iznosila je 93,1%. Rezultati ukazuju na važnost odabira odgovarajućih otpadnih tokova za anaerobnu digestiju, kako bi se optimizirao prinos bioplina i iskorištavanje organskog otpada kao izvora energije.The potato chip, flip, and other snack food production industry generates a considerable amount of waste during the manufacturing process, encompassing waste from raw material preparation as well as various technological stages of production. This study aimed to investigate waste streams rich in organic matter from the production of chips, flips, and other snack products, analyzing their potential for anaerobic digestion and biogas production. Additionally, the study focused on assessing biogas yield, expressed in terms of biogas and biomethane potential, based on the biodegradable fractions of waste generated within the industry. Laboratory analyses of dry matter, moisture, volatile matter, and ash content in the investigated waste streams revealed that chip samples exhibited the highest dry matter content (98.45%). A slightly lower dry matter content was recorded in a mixture comprising flips, popcorn, unpopped popcorn, and rice snacks. The highest volatile matter content was measured in sunflower/palm oil waste (99.99%), whereas the lowest was in starch sludge samples (75.64%). The sunflower/palm oil sample had the lowest ash content, while the starch sludge sample exhibited the highest ash content. Chemical Oxygen Demand (COD) values for all samples indicate that the substrates are suitable for biogas production. Regarding biogas and biomethane potential, methane content, and biodegradability, the starch sludge sample displayed the lowest biogas potential (359 NL/kg of dry matter) and the lowest biomethane potential (228 NL/kg of dry matter), with a biodegradability rate of 42.0%. These results align with expectations, as the starch sludge sample contained the lowest proportion of volatile (organic) matter, leading to reduced biodegradability compared to other samples. Conversely, the highest biodegradability, measured at 93.1%, was observed in the starch sample. The findings underscore the significance of selecting suitable waste streams for anaerobic digestion to maximize biogas production and enhance the utilization of organic waste as a renewable energy source
Validation and verification of a method for the determination of cadmium using graphite furnace atomic absorption spectrometry
No full textKadmij je visokotoksični teški metal koji predstavlja izuzetnu opasnost za ljudsko zdravlje i okoliš zbog čega je potrebno pratiti njegovu koncentraciju u okolišu, ali i uzorcima drugog porijekla. Atomska apsorpcijska spektrometrija s grafitnom peći (GF-AAS) omogućuje određivanje manjih koncentracija metala, za analizu su potrebne male količine uzorka pa je ova tehniku prikladna za
određivanje kadmija u uzorcima vode. U ovome je radu provedena validacija i verifikacija metode za određivanje manjih koncentracija kadmija u uzorcima vode pomoću atomske apsorpcijske spektrometrije s grafitnom pe i (GF-AAS). Ispitani parametri validacije uključuju linearnost, točnost, preciznost, granicu detekcije (LOD), granicu kvantifikacije (LOQ) i mjernu nesigurnost. Svi dobiveni parametri zadovoljavaju kriterije prihvatljivosti zadane od strane Američkog društva analitičkih kemičara (AOAC) i aktualnih Europskih regulativa: koeficijent korelacije R g 0,995, granica kvantifikacije f 0,1 μg/L, ponovljivost RSD f 8 % te iskorištenje od 50-121 %. Ispitivani su i izvori mjerne nesigurnosti: kalibracijski pravac, volumen mikropipete 10-100 μL i 100-1000 μL, volumen
tikvice 50 mL i 100 mL te ponovljivost mjerenja. Uspostavljeno je da je najveći izvor mjerne nesigurnosti ponovljivost mjerenja.Cadmium is a highly toxic heavy metal that poses an exceptional risk to human health and the environment, which is why it is necessary to monitor its concentration in the environment and in samples of other origins. Graphite furnace atomic absorption spectrometry (GF-AAS) allows the determination of low concentrations of metals, and small amounts of sample are making this technique suitable for the determination of cadmium in water samples. This paper deals with the validation and verification of a method for the determination of low concentrations of cadmium in water samples using graphite furnace atomic absorption spectrometry (GF-AAS). The validation parameters tested include: linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ) and measurement uncertainty. All obtained parameters meet the acceptance criteria set by the Association of Official Analytical Collaboration (AOAC) and current European regulations: correlation coefficient R g 0.995,
limit of quantification f 0.1 μg/L, repeatability RSD f 8 % and recovery of 50-121 %. The sources of measurement uncertainty were also examined: calibration curve, micropipette 10-100 μL and 100-1000 μL, volumetric flask 50 mL and 100 mL, and measurement repeatability. It was found that the largest source of measurement uncertainty was the measurement repeatability