Journal of the Serbian Chemical Society

Editorial

2024-05-13T22:23:42+02:00

Comparative study between homemade and commercial hawthorn (Crataegus spp.) extracts regarding their phenolic profile and antioxidant activity

2023-12-19T10:56:13+01:00

Crataegus species (hawthorn) have been commonly used in traditional medicine, especially for the treatment of congestive heart failure. Many studies confirmed that they are rich in polyphenols, thus exhibiting strong antioxidant activity, which contribute to the beneficial effects of hawthorn on the cardiovascular system. In the market, there are many herbal medicinal products based on hawthorn, which consumption as adjuvant therapy in heart-related issues is supported by European Medicines Agency. Since there is a global trend of making homemade herbal preparations, this study aimed to compare whether there is a difference in polyphenol profile and antioxidant potential between homemade and commercial ethanol extracts of hawthorn. Polyphenol profile was evaluated by determination of total phenolic and flavonoid contents, and by quantitative analysis of selected polyphenols by liquid chromatography–mass spectrometry/mass spectrometry. Antioxidant potential was examined by 2,2-diphenyl-1-picrylhydrazyl, ferric ion reducing antioxidant power and lipid peroxidation inhibition assays. The results of this study suggest that homemade ethanol extracts of hawthorn flowers, leaves and fruits are just as good source of polyphenols and antioxidants as commercial ones, and their utilization should be supported. Furthermore, hawthorn extracts made of leaves and flowers are better source of bioactive polyphenols and have higher antioxidant activity compared with the same of fruits, regardless of the method of preparation.

Effect of silver nanoparticles in treating and healing of burn wound

2023-12-28T16:36:54+01:00

The paper investigates the effect of silver nanoparticles preparations on the rate of burn healing and scar quality. Three preparations for burn treatment were considered: one with silver sulfadiazine and two with silver nanoparticles woven into two types of dressing: one, of polyethylene and second, carboxymethyl cellulose. The experiment was performed on pigs, due to anatomical and pathophysiological similarities with human skin. All three silver preparations have antimicrobial properties with a beneficial effect on the healing of burns. Preparations with silver nanoparticles proved to be the most effective, since they encourage very fast burn epithelialization, affect reduction of the level of matrix metalloproteinase-9 in the environment of the burn wound, lead to faster expression of vascular endothetial growth factor – VEGF, cause less thickening of the epidermis and contractility, and improve tension characteristics of the scar compared to the preparation with silver sulfadiazine. By comparing results of healing parameters and evaluation of the scar achieved with preparations with silver nanoparticles, it was evident that the best overall results of local treatment were achieved with silver nanoparticles in crystalline form. Due to quantum-mechanics, surface and chemical oxidation–reduction (reactive oxygen species) phenomenological characteristics Ag nanoparticles in crystalline form have unique ability to catalyze rate of healing.

Diffusion models of gentamicin released in poly(vinyl alcohol)/chitosan hydrogel

2024-01-17T17:45:53+01:00

This study presents comparison of our recently formulated two compartmental model with General fractional derivative (GFD) and Korsmeyer–Peppas, Makoid–Banakar and Kopcha diffusion models. We have used our GFD model to study the release of gentamicin in poly (vinyl alcohol)/chitosan/gentamicin (PVA/CHI/Gent) hydrogel aimed for wound dressing in medical treatment of deep chronical wounds. The PVA/CHI/Gent hydrogel was prepared by physical cross linking of poly(vinyl alcohol)/chitosan dispersion using freezing-thawing method, and then was swollen for 48 h in gentamicin soluteion, at 37 °C. Different physicochemical (FTIR, SEM), mechanical and biological (cytotoxicity, antibacterial activity) properties have been determined. The concentration of released gentamicin was determined using a high-performance liquid chromatography (HPLC) coupled with mass spectrometry (MS). The ratio between concentration of released gentamicin and initial concentration of gentamicin in the hydrogel was monitored for the prolonged time period in order to obtain gentamicin release profile. It was proven that our novel diffusion GFD model better fitted to experimental data then other models, and enabled the determination of diffusion coefficient precisely for the entire time period.

Immunohistochemical evidences of anticancer actions of metformin with other repurposed drug combinations and correlation with hamster fibrosarcoma tumor size

2024-01-03T10:05:12+01:00

The aim was to detect and correlate anticancer effects of metformin in combinations with other repurposed drugs, already registered for other indications, which may be immediately applied and clinically investigated in oncology, reducing the time and cost of research for new cancer treatments. Immunohistochemistry was performed for tumors treated by dual drug combinations containing metformin with deoxycholic acid, caffeine, itraconazole, nitroglycerin, disulfiram or diclofenac. The drugs were applied in Syrian golden hamsters (6 animals per group) with the inoculated BHK21/C13 fibrosarcoma in doses equivalent to usual human doses, <50 % LD₅₀. The anticancer effects were assessed by: p53 (mutational status); Ki-67 and PCNA (tumor proliferation); CD34 and CD31 (neoangiogenesis); GLUT1 (glucose metabolism); iNOS (NO metabolism); COX4, Cytochrome C and caspase 3 (apoptosis); immunohistochemical markers. Also, biophysical characteristics of fibrosarcoma, animal blood samples and the toxicity on main organs were analyzed. Treatments significantly (P < 0.05) reduced mutational status, tumor proliferation, neoangiogenesis, glucose metabolism, NO metabolism and modulated apoptosis, in correlation with tumor size, without toxicity and influence on biochemical blood and hematological tests. The administration of metformin in two-drug combination with deoxycholic acid, caffeine, itraconazole, nitroglycerin, disulfiram or diclofenac may be recommended for further clinical investigations in oncology.

A 7-year experience in core needle biopsy of breast lesions: Correlation between imaging and hematoxylin and eosin-stained sections

2024-01-16T09:20:22+01:00

Screening mammography is an imaging procedure which allows breast cancer detection in its early stage. The Breast Imaging and Reporting Data System (BI-RADS) determined six radiological categories for describing lesions. The core needle biopsy (CNB) is minimally invasive procedure that provides pathohistological samples. Via microscopic analysis, samples are categorized into five groups according to the B system for pathohistological report. The aim of the study was to follow the spectrum of pathohistological diagnoses; to define which BI-RADS and core categories are most commonly expressed in certain age groups; and to determine the incidence of histological diagnoses in different BI-RADS categories. The study included 631 patients and data was analysed in order to localise the lesion, BI-RADS and core category and pathohistological diagnosis. Within 631 biopsies, 33 diagnoses were given. In each age group, the findings indicating a high risk for malignancy were the most common (>2 %). The highest percentage of malignant categories was found in patients over the age of 61. Final diagnoses showed a deviation compared to the radiological categories, especially in BI-RADS4 category. Pathohistological diagnosis is always a definite confirmation of a breast lesion type and it has significant contribution to the evaluation of CNB quality.

The influence of the coprecipitation synthesis methods on photodegradation efficiency of ZnFe based photocatalysts

2023-12-07T11:05:26+01:00

Organic dye pollutants that are progressively used in modern chemical industries, emerged as a major source of water contamination. A promising eco-friendly and simple approach to water purification is the heterogeneous photocatalytic process that uses various metal oxide semiconductors in the presence of light, initiating the oxidation-reduction reactions resulting in dye degradation. The aim of this study was to investigate the influence of coprecipitation synthesis methods on photodegradation efficiency. The ZnFe based photocatalysts were synthesized using two different methods: low (LS) supersaturation and high (HS) supersaturation coprecipitation and thermally activated at 100, 300, 500 and 700 °C. Structural and textural characterisation were carried out and their efficiency in methylene blue photodegradation test reaction was studied. LS samples treated at 100 and 300 °C exhibited very low photodegradation efficiency (less than 10 %) when compared to HS samples treated at the same temperatures (75 and 85 %). The efficiency of LS 500 and LS 700 samples improved (67 and 75 %) with the increase in thermal treatment temperature and the photodegradation efficiency difference between LS and HS samples decreased. Such behaviour of LS and HS samples could be explained by structural and textural properties that originated from different synthesis methods.

Influence of the elasticity variation of the 3D printed PMMA structure on the axial tooth vibration

2024-02-15T11:13:53+01:00

Recently, 3D printing with poly methyl methacrylate (PMMA) has been widely used in dentistry: 3D printing is a suitable method for producing any complex three-dimensional shape, and PMMA is a material that has suitable properties in the oral cavity environment. That is why 3D printing is very often used to make PMMA teeth. There is the impact between teeth during chewing that causes shape variation and tooth vibration. As cyclic vibrations adversely affect the durability of PMMA teeth, they must be eliminated. The object of this work is to study the axial vibrations of a 3D printed tooth, as well as to give recommendations for modifying the PMMA structure with the aim of vibration damping. Tooth vibration is mathematically modeled and analytically solved. The obtained result provides a link between the vibrational properties and the elasticity variation of the PMMA material. The function that defines the change in elasticity of PMMA depends on the “slow time”. (The term “slow time” implies a product of time and a parameter that is less than one). For a decreasing elasticity function, the vibration is of damped type: for higher is the elasticity reduction, the faster is the vibration decay. Based on the determined elasticity function, the modification of the PMMA structure can be realized. Authors propose the application of the obtained elasticity variation function for programming 4D printing with modified PMMA.

Sulphur hexafluoride in modern medium-voltage switchgear: Advantages, hazards and environmental impact

2024-01-29T12:47:46+01:00

Sulphur hexafluoride is synthesised as a persistent and non-toxic gas with an exceptional dielectric strength. In contemporary medium-voltage switchgear within power distribution systems, SF₆ gas is used for the insulation and the extinction of electric arc. The application of SF₆ has advantages in terms of gas physicochemical characteristics and performance; the dimensions, the cost-effectiveness, the reliability of the switchgear equipment and the duration, as well as the cost of maintenance were significantly reduced. SF₆ is a known greenhouse gas, which tends to accumulate in the lungs, inducing oxygen depletion and respiratory complications. The by-products of SF₆ formed during the electric arc can be harmful and toxic. The equipment containing SF₆ is being replaced in the EU and worldwide. Using ALOHA^® software the scenarios of leakage for SF₆ and by-products were modelled in urban areas, where the switchgear is frequently placed. In areas where the circulation of wind is lower (urban areas), in hazardous situations, it is not possible to depend on high dispersion levels or minimisation of concentration and threat. The models have shown that SF₆ poses an environmental problem and its by-products cause a serious health hazard in the case of leakage in urban areas, rendering red threat zones from 10 to 60 m in radius.

Performance indicators model assessment for water system quality and supply in Montenegro

2023-12-28T16:41:12+01:00

The paper researches water quality, supply and management system assessment problems of the Montenegrin costal region. A significant problem is generated by seasonal tourism, the main branch of Montenegrin costal economy. The selected performance indicators model has been tested in the water supply system of the city Herceg Novi, as a representative experimental system for the Montenegrin costal area. The city Herceg Novi has 33.000 permanent residents and around 80.000 individual consumers during the summer touristic season. The research activities are based on the seasonal parameters defined by the monitored performance indicators of the water supply system. The study depicts the developed indicators performance model based on the obtained experimental monitoring data. Within the experimental analytical research performance an indicator matrix was established. The coastal area of Montenegro is experiencing over 50 % of water loss. Structure developed in the model applies the performance indicators and results in systematic losses reduction. The model takes into account the principle of seasonality, and the existence of two completely different periods of the year. This type of the experimental research with testing in situ was for the first time performed and implemented in the costal Adriatic region of Montenegro.

Cadmium and lead flow analysis as a decisions support data for waste management

2024-02-07T09:16:28+01:00

Striving for EU membership, the Republic of Serbia must adjust its waste management practices to comply with EU directives, including targets to reduce biodegradable waste disposal in landfills, as outlined in its Waste Management Program 2022–2031. Cadmium and lead, two highly toxic heavy metals, that are present in municipal solid waste, can pose high environmental and human health threats if not properly managed. The research evaluates how different technologies for biodegradable waste treatment influence the transformation of cadmium and lead flows through waste management systems. Hence, two waste management scenarios were modelled and developed for the Republic of Serbia, where the flows of cadmium and lead are monitored. The results indicate the differences between quantities and concentrations of cadmium and lead emitted in environmental media, thus confirming the various impacts of different waste technologies on achieving the vital goal of waste management – protection of the human health and the environment. The research concludes the crucial role of the versatile approach, where the quality of waste management outputs is highlighted.

Effects of carbonation and chloride ingress on the durability of concrete structures

2024-02-19T08:47:30+01:00

The durability of concrete structures, which are designed for long-term use is predominantly determined by the resistance to chemical influences, i.e., the concrete’s ability to protect the reinforcement steel. The carbonation and the chloride ingress into concrete are the most significant causes of steel corrosion and the potential failure of the structure. The primary goal is to ensure that any significant damage does not occur during the structure's service life, primarily achieved by selecting an adequate thickness of the concrete cover. The issue is approached through calculations based on performance analyses, and the use of appropriate models for these chemical phenomena. The paper provides a brief overview and the methodology for analysing the impact on the durability of concrete structures in accordance with the leading international normative documents. The emphasis is on the recent changes introduced in second generation of European Eurocode standards. The consequences of the analysed phenomena are presented through the results of field tests conducted at salt factories, coke industries, and thermal power plants, and through laboratory tests. The tests were performed in order to develop a rapid prediction method for the measure of chloride ingress into concrete without the stimulating chloride ion migration by electricity, as an alternative to standardized tests.

Effects of urban vegetation on PM mitigation: The case of a street in Novi Sad, Serbia

2024-01-19T10:14:32+01:00

Experiencing rapid development and growth, cities worldwide face a surge in air pollution, primarily driven by the increased concentrations of the particulate matter (PM) originating from various anthropogenic sources, such as traffic, household fuel combustion, and industrial and construction activities. Urban green spaces can naturally filter PM through physicochemical processes, serving as effective urban planning instruments for the improvement of the air quality. Focusing on a street in Novi Sad, the second-largest city in Serbia, this study investigates the efficiency of vegetation in mitigating air pollution, specifically PM₁₀ emissions from traffic and construction activities. Using the contemporary monitoring and modelling techniques for measuring and predicting PM₁₀ concentrations, the focus of this research is to evaluate the efficacy of vegetation in affecting and minimizing detected PM concentrations. The results indicate a significant reduction in the monitored PM₁₀ concentrations behind the green barrier compared to the modelled concentrations near the pollution source (on the road) for both traffic and construction-related emissions. The paper highlights the capacity of green elements to act as natural air pollution mitigators and suggests better integration of strategic environmental management into urban planning to foster the development of healthier and more sustainable cities, providing recommendations to facilitate this objective.

Chemical engineering in technical and technological culture

2024-01-10T11:18:37+01:00

Modern technologies continuously change humans and their relationship with the environment. They can achieve a lot in the field of chemical engineering, thereby improving and enhancing the quality of human life, but on the other hand, technologies can be used to destroy human lives. Technical and technological culture (hereinafter referred to as TTC) is the entirety of social achievements in the field of technical and technological sciences and their application, as well as of the all knowledge and skills needed to understand the achievements, use them correctly, transfer them to the younger generation and create new values in this field. This paper will present a pilot study aimed to examine the attitudes and beliefs of engineers, Technological (chemical engineering) and Technical faculties, regarding the development of TTC and to determine socio-demographic factors that may influence its development. The research was conducted in Serbia and Croatia. The results indicate that the most important aspects of TTC are: the development of awareness of sustainable development, the impact on environmental protection, etc. The respondents recognized the ethical challenges we face today, the need for the education of young engineers and the promotion of TTC in the media and professional public.

Cultural heritage in the face of climate change: From protection to decolonisation

2024-02-21T16:49:44+01:00

The risks climate change poses to cultural heritage have garnered increased attention in recent decades, prompting reactions from organizations such as UNESCO and ICOMOS. While there is a consensus among heritage actors that the climate crisis requires a departure from “business as usual”, there is no unanimity regarding which aspects of heritage protection should remain unchanged and which necessitate transformation, nor what level of action and transformation is required. Such disagreements may not always be immediately apparent, as different approaches are often mentioned within the same policy paper or call for action. They offer different interpretations of the climate crisis impacts, different framings of what is at stake, and different political visions regarding the necessary steps, thus creating tensions. This paper utilizes maximum variation sampling to identify and analyse groups of approaches through which climate change has been addressed within the cultural heritage field, ranging from technical protection to decolonisation. It highlights the significance of grasping their political and eco-social underpinnings, crucial for fostering transdisciplinary dialogues that draw upon the expertise of natural and social sciences, engineering and humanities to alleviate tensions, jointly shape future actions and develop sustainable solutions that respect and protect heritage while fostering regenerative socio-ecological relations.