Carbonation is inevitable process during the service life of concrete structures, where CO2 causes decalcification of the calcium-bearing phases. These changes affect the durability of concrete and accelerate the corrosion of reinforcement. Alkali-activated materials (AAMs) are alternative, cement-free binders based on aluminosilicate rich precursor and alkaline activator. The interest in AAMs increased during the last century, due to the production process with low CO2 footprint comparing to Portland cement (PC) concrete, the possibility to use wide range of industrial by-products as precursors and comparable performance to PC concrete. Despite the extensive research in this field, the carbonation resistance of AAMs needs to be better understood, due to the differences and complexity of binder chemistry compared to PC concrete. The propagation of carbonation process will depend on chemical composition of the precursors and the type and dosage of activators. This paper presents the results of microstructural changes of three alkali-activated concrete mixes after exposure to accelerated carbonation. Ground granulated blast furnace slag was used as a precursor and sodium hydroxide and sodium silicate as activators. Three mixes have constant water to binder ratio and slag content, while alkali content and silica modulus were varied. The carbonation resistance was evaluated by testing carbonation depth after 7 and 28 days of exposure in carbonation chamber. Microstructural changes during carbonation were investigated by thermogravimetric analysis and mercury intrusion porosimetry.

Alkali-activated materials (AAM) consist of a precursor, which is a source of aluminosilicates, and an alkali source. The precursors are usually waste materials from various industries such as fly ash from thermal power plants and slags from the metallurgical industry. Due to the increasing use of these materials in the cement industry and strategies for decommissioning coal-fired power plants, alternative raw materials from waste streams are increasingly being explored. One of these materials is waste from the aluminium industry, known as red mud. Due to its chemical composition, which is similar to that of other cementitious materials, red mud is suitable for use in the cement industry. It can also be used as a source of aluminosilicates in the synthesis of AAM. In this study, the corrosion behaviour of steel in chloride exposed AAMs based on fly ash and slag was investigated with and without the addition of red mud. During exposure of AAM to tap water and a 3.5 wt.% NaCl solution, the corrosion process was monitored by corrosion potential and polarisation resistance. AAM mixes containing red mud exhibited better corrosion resistivity and lower current density values compared to mixes without red mud, indicating a possible contribution of the red mud to chloride binding and improving the passivity of the steel.

Recently, the cement industry has faced new challenges in addition to the environmental constraints of the last decade. The decline in availability and current inconsistent prices of common supplementary cementitious materials (SCMs), such as by-products from the iron industry or coal-fired power plants, have opened the search for more reliable materials. Research on cements containing calcined clays now serve as a possible solution to the forementioned problems. Clays containing the mineral kaolinite in sufficient quantities, when calcined and mixed with limestone powder, produce hydration products that can improve the strength and durability of concrete. In addition, the production of limestone calcined clay is reported to be less CO2 intensive, but this eco-efficient solution is viable only if the materials are locally available. For this reason, this study investigates the possibility of using natural clays from the Southeast European region (SEE) as cement replacements. A systematic experimental study was conducted on 18 different clays from 13 different deposits to determine the physical and mineralogical composition of the raw clays, their reactivity and mortar strength. The results were then related to the environmental contributions they might have in comparison with ordinary Portland cement in concrete.

There are now several initiatives to reduce the carbon footprint of cement production, such as the use of alternative binders for clinker. However, reducing the carbon emissions of the cement sector will only be possible when design optimization is combined with other measures. The construction industry is reluctant to reduce the cement content of concrete mixes and is not encouraged to use performance-based design for concrete. In most cases, these steps will negate the benefits of using alternative binders in concrete. The objective of this paper is to investigate the effects of lowering the cement content and additionally substituting part of the cement on the mechanical properties and durability of concrete. The reference mix was taken from a real bridge recently built in Croatia, and the alternative combination was prepared with a reduced cement content of 22%. All mixes were evaluated based on their mechanical strength and resistance to chloride penetration. The carbon footprint of each mix was also studied. The study concluded that the alternative mix with lower cement content had comparable durability and a significantly lower carbon footprint, meaning that the alternative mix proved to be a more sustainable option.

Throughout their service life, concrete structures are exposed to various environmental conditions that affect their durability. The cementitious matrix inevitably comes into contact with air, which leads to a progressive carbonation reaction. As a result of carbonation, changes occur in the microstructure and porosity of the cementitious matrix. Calcium aluminate cement is produced to increase the resistance of composites to aggressive environments, but its application is limited by the occurrence of conversion process. The addition of slag inhibits the conversion process of calcium aluminate cement and prevents a reduction in compressive strength due to the formation of C2ASH8 hydrate, while contributing to the net zero commitment of the cement industry. It remains an open question how these changes in microstructure caused by the addition of slag affect the carbonation rate of calcium aluminate cement-based concrete. Therefore, the objective of this study was to determine the effects of slag on the microstructure and porosity of calcium aluminate-based concrete before and after accelerated carbonation. For this purpose, the mechanical properties, porosity, and reaction product of a concrete mix containing 30% calcium aluminate cement replacement by slag were compared to calcium aluminate cement-based concrete before and after exposure to 3% CO2 for 7 and 28 days. Thermogravimetric analysis (TGA) and mercury intrusion porosimetry (MIP) were tested to understand the changes in reaction products and pore size distribution, respectively.

The paper presents an examination of the possibility of applying raspberry flower extract (Rubus idaeus L.) as a green inhibitor of general corrosion of copper in 3% NaCl. Raspberry flowers (Rubus idaeus L.) sort Polka were collected from the Moševac near Maglaj city, Bosnia and Herzegovina. Raspberry flower extract in ethanol was obtained by ultrasonic extraction. A significant content of polyphenol was found in the raspberry flower extract by UV/VIS spectrophotometry analysis. Results obtained by DC techniques (by the methods of Tafel extrapolation, potentiodynamic polarization and linear polarization) prove that the corrosion rate decreases in the presence of the raspberry flower extract. Tests performed by the method of electrochemical impedance spectroscopy prove that the tested extracts slow down the kinetics of the corrosion process, which is visible through the increase in resistance. The results of the conducted tests prove that in an aggressive medium, such as 3% NaCl solution, Polka raspberry flower extract can be used as an inhibitor of copper's corrosion.

The line graph L(G) of a graph G is defined as a graph having vertex set identical with the set of edges of G and two vertices of L(G) are adjacent if and only if the corresponding edges are incident in G. Higher iteration L i(G) is obtained by repeatedly applying the line graph operation i times. Wiener index W(G) of a graph G is defined as the sum of distances which runs over all pairs of vertices in G. The problem of establishing the extremal values and extremal graphs for the ratio W(L i(G))/W(G) was proposed by Dobrynin and Melnikov [Mathematical Chemistry Monographs, Vol. 12, 2012, pp. 85-121]. In this paper we establish the maximum value and characterize the extremal graphs for i = 1. In doing so, we derive unexpectedly an interesting relation that involves the Gutman index and the first Zagreb index.

In the last decade, there have been many reports on the negative impact of wildfires on various ecosystems. Unfortunately, wildfires have been intensifying as global temperatures, droughts, and other instances of extreme weather events rise around the world. These circumstances are forcing communities to vigorously address the uncontrolled spread of wildfires, where the ultimate goal is the protection of wildlife. At the same time, many disaster prevention and monitoring methods, based on image processing and computer vision, have been developed. In this paper, we present a new unsupervised method based on RGB color space for the early detection of wildfires from still images. From the analysis of existing state-of-the-art methods, it is evident that different methods explore different color spaces for the extraction of flame features. Our motivation was to use only RGB color space and thus eliminate the time-consuming task of color space conversion. The proposed method consists of several new image processing techniques used to efficiently extract flame features. It outperforms the existing methods, where an increase of 3% and 2% is recorded in the F1 score and Matthews correlation coefficient, respectively. Such performance demonstrates the merits of the proposed method for flame segmentation and detection.

Uvod: U današnje vrijeme kao glavni alat za procjenu starosti u forenzičkoj medicine koriste se radiološki snimci. Pojavom kompjuterizirane tomografije konusnim snopom omogućen je 3D uvid u anatomske strukture zuba, a samim tim unaprijeđen i olakšan proces identifikacije, obzirom da su zubi najtvrđi dio ljudskog tijela i kao takvi se često koriste za procjenu starosti. Cilj rada je ispitati radnu hipotezu prema kojoj dentalna dob procijenjena metodom volumetrijske analize pulpe kompjuteriziranom tomografijom konusnim snopom odgovara hronološkoj dobi ispitanika. Metode: Kroz ovu prospektivnu pilot studiju analizirani su CBCT snimci bosanskohercegovačke populacije kod 30 ispitanika (17 žena i 13 muškaraca). Snimci su u .DICOM formatu importovani u ITK Snap program pomoću kojeg je izmjeren volumen pulpe zuba interkaninog sektora gornje i donje vilice, i to za očnjake, centralne i lateralne sjekutiće. Kriteriji za uključivanje podrazumijevali su odsustvo kalcifikacije, artefakata i bez većih restauracija kod navedenih zuba. Podaci o svakom mjerenju korelirani su sa dobi i spolom ispitanika. Statistička obrada i interpretacija prikupljenih podataka urađena je pomoću statističkog programa SPSS. Rezultati: Provedeno istraživanje je potvrdilo da se volumen pulpe zuba smanjuje sa godinama starosti. Dob ispitanika je varirala između 16 i 54 godine. Najmanji volumen pulpe izmjeren je kod centralnog sjekutića mandibule, a najveći kod maksilarnog očnjaka. Volumen pulpe zuba gornje vilice općenito je bio veći nego kod zuba donje vilice. Kod žena je zabilježen manji volumen pulpe zuba u odnosu na volumen pulpe kod muškaraca. Zaključak: Kod svih analiziranih zuba postojala je značajna korelacija između dobi i volumena pulpe zuba, sa jačom korelacijom kod muškaraca. Studija je pokazala da se dob može procijeniti na osnovu poznavanja volumena pulpe zuba interkanine regije, uz uspostavljanje matematičkog modela za koji je potreban veći broj ispitanika.

Funkcionalna magnetna rezonanca (fMRI) je neinvazivna dijagnostička metoda koja služi za vizualizaciju nervne aktivnosti u ljudskom mozgu. Svoju primjenu je našla u neurologiji i omogućava bolje praćenje bolesti, njihovu klasifikaciju, prognozu i liječenje. To je sigurna i ponovljiva metoda, kako za djecu tako i za odrasle, te je svoju primjenu našla i u drugim naukama. Ovaj pregledni rad uključuje 20 naučno–istraživačkih radova, koji su u svojim rezultatima opisali tehniku izvođenja fMRI, njene prednosti i ograničenja, kao i oboljenja u kojima je našla kliničku primjenu. Primjenom fMRI u praksi počela je revolucija u polju neuroimaging-a. Umjesto da magnetna rezonanca daje samo anatomsku sliku i neke osnovne fiziološke informacije, sada je mogla da proizvodi dinamičke mape aktivacije mozga. FMRI se ne treba smatrati konkurentskom metodom, već komplementarnom, te umjesto da se koristi u svrhu pobijanja ili potvrđivanja određene dijagnoze, ona bi se mogla koristiti kao dopunska metoda za mnoge konvencionalne testove.

Uvod: Adenomi hipofize su benigni tumori prednjeg režnja hipofize i čine 10% svih intrakranijalnih tumora. Metoda izbora za njihovu evaluaciju i dijagnostiku je magnetna rezonanca. Pruža korisne informacije o odnosu hipofize sa susjednim anatomskim strukturama i temelj je dijagnoze, nadzora, planiranja medicinske ili hirurške strategije i procjene odgovora na liječenje. Metode: U ovom istraživanju uključeno je 14 randomiziranih prospektivnih i retrospektivnih studija, sistemskim odabirom na internet bazama: PubMed, Google Scholar, Crossref i Researchgate. Ispitanici su različite starosne i spolne strukture. Razmotrene su studije koje su uključivale magnetnu rezonancu hipofize i njen značaj i senzitivnost prilikom dijagnostike adneoma hipofize. Ciljevi: Utvrditi značaj magnetne rezonance u dijagnostici adenoma hipofize. Komparirati magnetnu rezonancu sa ostalim radiološkim modalitetima snimanja hipotalamo-hipofizne regije te utvrditi senzitivnost magnetne rezonance prilikom dijagnosticiranja mikroadenoma. Rezultati: Na osnovu sistemskog pregleda literature ustanovljeno je da MRI ima visoku detekciju prilikom dijagnostike adenoma hipofize. Kompjuterizirana tomografija ostaje metoda izbora kada magnetna rezonanca nije dostupna i u slučajevima kada se ona ne može uraditi. Korištenjem dinamskog CT-a poboljšava se detekcija mikroadenoma u odnosu na protokol snimanja hipofize magnetnom rezonancom.