Effect of Different Types of Fly Ash on Properties of Asphalt Mixtures

In order to preserve natural resources, the use of waste and alternative materials in the construction and maintenance of roads is increasingly investigated. This paper presents the results of testing wearing course asphalt mixtures (AC 11s SURF 50/70) made with various percentages of fly ash, used as a partial or complete substitute for mineral filler. The properties of fly ash were determined to assess their suitability for use in asphalt mixtures. The experimental research was performed on asphalt samples containing fly ash from three different sources, with 25%, 50%, 75%, and 100% of mineral filler substitution. The control mixture was prepared with 100% of mineral filler. The paper presents the volumetric composition, stability, and flow of asphalt mixtures tested on standard Marshall’s samples, water sensitivity, and resistance to permanent deformation. The results of this study indicate that a satisfactory volumetric composition can be achieved by adding fly ash, while the bulk density and voids of the mineral and asphalt mixture generally depend on the type of fly ash and its content. The stability and flow of mixtures with fly ash are favourable compared with the control mixture. The water sensitivity of mixtures with fly ash is generally lower compared with the control mixture and depends on the type and percentage of fly ash. The resistance to permanent deformation of the asphalt mixtures depends on the fly ash type and percentage. The results obtained in this study are an important step towards broader implementation of fly ash in asphalt mixtures.Article ID 8107264, 11 page

Physicochemical characterization of mechanochemically activated pyrophyllite/Ag composites

Nanocomposites synthesized by incorporating nanostructured materials within the interlayer spaces of clay minerals have gained tremendous interest lately, owing to their exceptional physicochemical properties and vast potential in various fields. This study focuses on the mechanochemical activation of pyrophyllite, a commonly used natural clay material, using AgNO3 at different concentrations (2, 5, and 10 wt%). The activation process involved grinding the materials for varying durations ranging from 20 to 320 minutes. The resulting samples were analyzed using FTIR, TGA, and DTA thermal analysis techniques, XRD, SEM with EDX as well as PSD method for particle size distribution analysis. The results have shown a homogeneous distribution of silver along the analyzed surface. The duration of grinding and the amount of added silver greatly influence the composite physicochemical properties.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

A gene expression profile associated with relapse of cytogenetically normal acute myeloid leukemia is enriched for leukemia stem cell genes

Some 50 – 80% of patients with acute myeloid leukemia (AML) achieve a complete remission with contemporary chemotherapy protocols, yet the majority of them eventually relapse with resistant disease: some patients no longer respond to chemotherapy at disease recurrence; others accomplish second and even third remissions whose decreasing duration nevertheless indicates that the pool of residual leukemic cells, i.e. of cells that persisted during treatment with cytotoxic drugs, increases with every round of therapy [1]. Either of these clinical courses therefore refl ects an enhanced chemotherapy resistance of leukemic cells at relapse as compared to the cell population at diagnosis. Molecular changes enabling malignant cells to survive exposure to cytotoxic drugs may already have been present in a subset of the leukemic cell population at presentation, or may emerge during treatment [2,3], but in any case are thought to be selected as a consequence of drug therapy, and to play a major role in therapy resistance at relapse. Remarkably, however, even though various types of molecular alterations may be acquired at relapse, neither specifi c cytogenetic alterations nor functionally relevant point mutations as identifi ed by whole genome sequencing were associated with relapse in a recurrent manner [2,3]. Certain copy number variations and known AML associated point mutations were newly present at relapse in small proportions of patients (usually 10%), but the latter were lost in other patients, indicating that they are unlikely to represent drivers of therapy resistance at disease recurrence [4]. Th ese fi ndings could either indicate that chemotherapy resistance at relapse is acquired through a large variety of different mechanisms, or that molecular changes of other types than those mentioned above are of more general relevance in this context. Indeed, an earlier study has suggested that the expression of specifi c genes may change in a consistent manner between diagnosis and relapse of AML [5]. However, only a limited number of genes and mostly unpaired samples were probed in this investigation. Th erefore, in the present study, genes whose expression changed in a relapse-specifi c manner were sought in a set of paired AML samples and on a genome-wide scale. To limit the genetic heterogeneity of the study population, only samples from patients with cytogenetically normal (CN) AML were used.Letter to the Edito

Improvement of sorption properties of natural clay pyrophyllite by ultrasonic treatment

Pyrophyllite, a naturally abundant clay material, exhibits remarkable physicochemical characteristics. Its minimal electrical and thermal conductivity, low expansion rate, strong mechanical properties, and outstanding heat resistance make it a valuable resource across diverse industries. Pyrophyllite finds applications in sectors such as paper and plastic manufacturing, brick production, ceramics, cosmetics, rubber processing, and wastewater treatment. Furthermore, its versatility extends to the production of ceramic membranes for efficient water filtration. This paper presents the characterization of natural pyrophyllite ore subjected to ultrasonic treatment at varying time intervals. The ultrasonic treatment aims to eliminate hard phases such as quartz and calcite within the ore, thereby improving its sorption capabilities. The treated samples were subjected to analysis using SEM and XRD techniques. Morphological and structural analysis revealed that as the duration of ultrasonic treatment increased, the proportion of hard phases in the sample decreased. Additionally, this study evaluated the sorption properties of pyrophyllite. A comparative analysis was conducted between a raw clay sample containing various admixtures and a sample that underwent a 30-minute ultrasonic treatment. The sorption of a methylene blue solution after 24 hours in water was assessed, with UV-Vis analysis revealing that the efficiency of the sonically treated pyrophyllite exceeded 97%, whereas the raw ore exhibited approximately 89% efficiency over the same duration. These findings suggest that the removal of hard phases from pyrophyllite ore enhances its sorption propertiesTwenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Detekcija fungicida karbendazima u vodi primenom elektrode od ugljenične paste modifikovane pirofilitom

Ovaj rad ima za cilj da dizajnira elektrodu od ugljenične paste modifikovanu pirofilitom za potencijalnu upotrebu za detekciju pesticida u vodenim rastvorima. Strukturna i morfološka karakterizacija prirodne gline pirofilit i mehanički modifikovanog pirofilita urađena je rendgenostrukturnom analizom i skenirajućom elektronskom mikroskopijom. Elektrohemijske karakteristike ove elektrode ispitivane su cikličnom voltametrijom u 1 mM K4Fe(CN)6 u 0,1 M KCl i 0,5 M H2SO4 i diferencijalnom pulsnom „striping“ voltametrijom u Briton-Robinsonovom puferu na pH 4. Pokazano je da maksimum na + 0,96 V u odnosu na Ag/AgCl elektrodu potiče od oksidacije karbendazima na pH 4 u Briton-Robinsonovom puferu. Dobru stabilnost i osetljivost pokazala je elektroda koja je sadržala 50% ugljenične paste i 50% pirofilita mehanički modifikovanog 15 minuta u mlinu sa kuglama. Razvijena metoda je linearna u opsegu od 1 ppm do 10 ppm sa r= 0,999 i granicom detekcije od 0,3 ppm.10. Memorijalni naučni skup iz zaštite životne sredine "Docent dr Milena Dalmacija", Mart 30.- 31., Novi Sad, 2023

Kinetic behavior of MgH2-transition metal composites: towards hydrogen storage

Hydrogen as an energy vector represents great potential, due to its high gravimetric density and low mass, as well as the fact that combustion does not emit harmful chemical byproducts. Hydrogen has the highest energy density per unit mass compared to any other fuel but a rather low energy density per unit volume. Further, hydrogen storage is a key technology for developing a hydrogen and fuel cell-based economy [1]. Metal hydrides as alternative hydrogen carriers have a wide range of performance parameters such as operating temperature, sorption kinetics, activation conditions, cyclic options, and equilibrium hydrogen pressure. These parameters can be improved or adjusted to meet the technical requirements of different applications. The most commonly used method for hydride destabilization is nanostructuring by mechanical milling which leads to a reduction in the particle and crystallite size of the MgH2 powder. Nanostructuring is often combined with catalyst addition and composite formation [2,3]. The most of research is focused on the morphological, structural, and thermodynamic effects typical for long milling times, while in this work we have followed the changes taking place under short milling times. The thermal stability of magnesium hydride is related to - changes in the crystallites and powder particle size. The analysis also considered the changes in activation energy. MgH2-M composites were prepared by mechanical milling of the as-received MgH2 powder (Alfa Aesar, 98% purity) with the addition of 2 and 5 wt.% of M (M= V, W, Mo). Mechanical milling was performed in s SPEX 5100 Mixer Mill using 8mm diameter milling ball. Samples were milled for 15-45 minutes under the inert atmosphere of argon and a ball-to-powder ratio 10:1 Figure 1. shows the kinetic curves obtained for composites with 5wt% of vanadium. To investigate the desorption process in detail, different models of solid-state kinetics were used as implemented in the code developed in our group. The ratelimiting step of the desorption reaction was determined using the iso-conversional kinetic method due to better accuracy of obtained apparent activation energies. As shown in Table 1 a decrease in apparent activation energies has been observed. It is obvious that the sorption kinetics is affected by material preparation because the reactivity of magnesium with hydrogen is strongly modified by changes in several surface parameters that govern the chemisorption, the dissociation of molecular hydrogen, and hydride nucleation7th MESC-IS 2023 : International Symposium on Materials for Energy Storage and Conversion : 11th INESS : International Conference on Nanomaterials & Adv. Energy Storage Systems : October 7-10, Baku, 2023

Natural Clay Pyrophyllite Activation with Silver and Composite Characterization

In this work, a hybrid pyrophyllite/AgNPs system was designed by mechanochemical activation of pyrophyllite, Al2Si4O 10(OH) 2. Tuning this system’s properties is especially important in terms of possible biomedical applications. The reaction was triggered by adding 2, 5, and 10wt% of silver in the form of AgNO3, indicating green synthesis of AgNPs. Thereby, the grinding time was adjusted from 20 to 320 minutes. The collected samples were analyzed by FTIR, XRD, SEM with EDX, TGA, DTA and PSD. The FTIR spectra of the pyrophyllite/AgNPs system showed the disappearance of some bands characteristic of pyrophyllite itself due to breaking of some bonds during the grinding, and the appearance of some new bands. SEM-EDS analysis confirmed that pyrophyllite structure changed during the mechanochemical treatment, indicating a homogeneous distribution of silver along the analyzed surface. PSD analysis showed that the average particle size distribution is approximately the same for all samples, despite the different wt% of silver. While XRD patterns of samples with 2 and 5 wt% of AgNO 3 did not show reflections originating from silver, the peak at 38.16˚ of the pyrophyllite sample milled for 20 minutes with 10 wt% of silver could be assigned to silver in the metal form. DTA curves of pyrophyllite/AgNO 3 samples milled for 20, 80 or 320 min had similar shapes for different silver content added. TGA curves of pyrophyllite/AgNO 3 samples milled for 20 min with 2, 5, and 10 wt% of silver showed a total weight loss of about 10% while for samples milled for 320 min reduced weight loss was observed due to the agglomeration of particles.Published in Bulletin of the Chemists and Technologistsof Bosnia and Herzegovina as Special Issue (2024)

Application of a Pyrophyllite Modified Carbon Paste Electrode for the Detection of Carbendazim Fungicide in Water

This work aims to design an electrochemical sensor for pesticide detection in food and water based on modified pyrophyllite. Pyrophyllite is a phyllosilicate mineral of the chemical formula Al2Si4O 10(OH) 2. Modification of the carbon paste electrode was made by the addition of mechanochemically modified pyrophyllite. This type of modification is an environmentally friendly green chemistry method because it avoids using solvents. It was found that the best physicochemical characteristics for constructing the electrochemical sensor were shown by the sample that was milled for 15 minutes. Due to the delamination and bending of the layers, the size of the particles and crystallites decreases, and the electrocatalytic activity of the modified electrode is improved. Electrochemical measurements were performed by cyclic voltammetry in 0.5 mol/L H 2SO 4 and 1 mmol/L K 4Fe(CN) 6 in 0.1 mol/L KCl. The results showed that the electrode made of 50 % carbon paste and 50 % mechanochemically ground pyrophyllite for 15 minutes had the best properties. Quantitative detection of carbendazim was done by differential pulse stripping voltammetry at different pH in the Britton Robinson buffer. The developed method shows the linearity at pH 4 in the range of (1–10) mg/kg, with r = 0.999 and a detection limit of 0.3 mg/kg. In contrast to earlier works, in which carbendazim was determined electrochemically with different types of electrodes, the detection limits obtained with the carbon paste electrode modified with pyrophyllite, which was ground for 15 minutes in this work, are significantly lowerPublished in Bulletin of the Chemists and Technologistsof Bosnia and Herzegovina as Special Issue (2024)

Enhancing Pyrophyllite Adsorption Capabilities Via Sonic Treatment

Adsorption, a highly efficient water purification method and tool for pollution control, utilizes materials like clay. Compared to other commercial adsorbents, clay offers notable advantages including affordability, large specific surface area, accessibility, high ion exchange capacity, excellent adsorption properties, and non-toxicity. Pyrophyllite, among abundant natural clays, stands out due to its layered structure without interlayer cations or water molecules, offering favorable physical and chemical attributes. This study specifically examines the characterization of natural pyrophyllite ore treated with ultrasonic waves for 30 minutes and 6h. Analysis of samples using X-ray diffraction (XRD) technique indicates the removal of hard phases such as quartz and calcite from both treated samples in comparison to the raw ore. Energy dispersive X-ray spectroscopy (EDS) analysis, conducted as part of SEM-EDS analysis, revealed a significant reduction in the weight % of silicon. Specifically, the Si content decreased from 35.1 weight % in the raw ore to 28.7 after half an hour of treatment. Subsequently, after 6 hours, the most effective purification was achieved, with the Si content reaching only 18.6 weight %. Furthermore, UV-VIS analysis testing the sorption of a methylene blue solution in water reveals that ultrasonically treated pyrophyllite for 30 minutes achieves 97% efficiency after 24 hours, surpassing the 89% efficiency of the raw ore. Notably, after 6 hours of ultrasonic treatment, efficiency reaches nearly 98% after just 1 hour, confirming high efficacy of ultrasonic treatment on adsorption ability of pyrophyllite.Published in Bulletin of the Chemists and Technologistsof Bosnia and Herzegovina as Special Issue (2024)