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Item REDUCING THE CARBON FOOTPRINT IN THE CONSTRUCTION SECTOR BY REPLACING CERAMIC BRICKS WITH ALTERNATIVE MATERIALS(2024-01-01) Tashkov L.; Zlateva P.; Penkova N.The use of non-fired materials with additives of vegetable waste instead of traditional building ceramics reduces the energy input and the carbon footprint in the construction sector. This applies to one- and two-story buildings due to the lower load-bearing capacity of non-fired bricks. A possibility for substitution of the fired ceramics with non-fired clay bricks with additives of straw at the building of the walls of a single-family house is analyzed. The subsequent reductions of the embodied energy, carbon dioxide, and thermal losses of the buildings are determined.Item ENHANCING SURFACE CHARACTERISTICS OF AA2024-T3 AIRCRAFT ALLOY THROUGH SYNERGISTIC ANODIZATION AND CERIUM CONVERSION COATING. PART I: PERFORMANCE IN MODEL CORROSIVE MEDIUM(2024-01-01) Portolesi S.; Girginov C.; Kozhukharov S.; Lilova V.; Petkov P.The present study is devoted to the monitoring of the performance of AA2024-T3 specimens, after the formation of Anodic Aluminum Oxide (AAO) layer and/or deposition of a Ceruim Conversion Coating (CeCC), obtained at 20°C and 50°C, respectively. Although both methods are well described in the literature, there is no sufficient information regarding the effect of their combination on their behaviour in corrosive media. The performance of the respective specimens was elucidated after 24 h of exposure to 3.5 % NaCl model corrosive medium (MCM) by means of Electrochemical Impedance Spectroscopy (EIS) and acquisition of Potentiodynamic Scanning (PDS) curves. Since the combined AAO/CeCC coating primers revealed superior barrier properties, the respective specimens were subjected to long-term corrosion tests of up to 672 h of exposure to the MCM to evaluate their durability. The results revealed the synergistic effect of the combination of the surface treatment procedures on effective corrosion mitigation.Item Novel Peptide Analogues of Valorphin-Conjugated 1,8-Naphthalimide as Photodynamic Antimicrobial Agent in Solution and on Cotton Fabric(2024-11-01) Staneva D.; Todorov P.; Georgieva S.; Peneva P.; Grabchev I.For the first time, N-modified analogues of VV-hemorphin-5 (Valorphin) were synthesised and conjugated with three different 4-substitured-1,8-naphthalimides (H-NVal without substituent, Cl-NVal with chloro-substituent, and NO2-NVal with nitro-substituent). Cotton fabric was modified with these peptides by soaking it in their ethanol solution, and the colourimetric properties of the obtained fabric were measured. The fluorescent analysis shows that peptide immobilisation on a solid matrix as fabric decreases the molecule flexibility and spectrum maxima shift bathocromically with the appearance of a vibrational structure. The peptides’ contact antimicrobial activity, and the resulting fabrics, have been investigated against model Gram-positive B. cereus and Gram-negative P. aeruginos bacteria. For the first time, the influence of light on bacterial inactivation was investigated by antibacterial photodynamic therapy of similar peptides. Slightly more pronounced activity in liquid media and after deposition on the cotton fabric was obtained for the peptide containing 4-nitro-1,8-naphthalimide compared to the other two peptides. Immobilisation of a peptide on the surface of fibres reduces their antimicrobial activity since their mobility is essential for good contact with bacteria. Cotton fabrics can be used in medical practice to produce antibacterial dressings and materials.Item Effect of extraction methods on polyphenols, flavonoids, mineral elements, and biological activities of essential oil and extracts of mentha pulegium l.(2022-01-01) Messaoudi M.; Rebiai A.; Sawicka B.; Atanassova M.; Ouakouak H.; Larkem I.; Egbuna C.; Awuchi C.G.; Boubekeur S.; Ferhat M.A.; Begaa S.; Benchikha N.Our study evaluated the in vitro antioxidant properties, antibacterial and antifungal activities, anti-inflammatory properties, and chemical composition of the essential oils (EOs), total phenol, and total flavonoid of wild Mentha pulegium L. This study also determined the mineral (nutritional and toxic) elements in the plant. The EOs were extracted using three techniques—hydro distillation (HD), steam distillation (SD), and microwave-assisted distillation (MAD)—and were analyzed using chromatography coupled with flame ionization (GC-FID) and gas chromatography attached with mass spectrometry detector (GC-MS). The antioxidant effects of the EOs were tested with 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), while the antibacterial and antifungal activities of the EO and methanolic extract were tested using Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. Twenty-six compounds were identified in the essential oil, representing 97.73% of the total oil, with 0.202% yield. The major components were pulegone (74.81%), menthone (13.01%) and piperitone (3.82%). Twenty-one elements, including macro-and micro-elements (Ba, Br, Ca, Cl, Co, Cr, Cs, Eu, Fe, K, Mg, Mn, Mo, Na, Rb, Sb, Sc, Sr, Th, U and Zn), were detected using neutron activation analysis (INAA) and inductively coupled plasma optical emission spectrometry (ICP-OES), with the concentration of mineral element close to the FAO recommendation. The results show that the EOs and extracts from Mentha pulegium L. had significant antimicrobial activities against the microorganisms, including five human pathogenic bacteria, one yeast (Candida albicans), and one phytopathogenic fungi. The in vivo anti-inflammatory activities of the leaf extracts were confirmed. The results indicate that the EOs and extracts from Mentha pulegium L. have promising applications in the pharmaceutical industries, clinical applications, and in medical research.Item Desert Endemic Plants in Algeria: A Review on Traditional Uses, Phytochemistry, Polyphenolic Compounds and Pharmacological Activities(2023-02-01) Hemmami H.; Seghir B.B.; Zeghoud S.; Ben Amor I.; Kouadri I.; Rebiai A.; Zaater A.; Messaoudi M.; Benchikha N.; Sawicka B.; Atanassova M.Due to their robust antioxidant capabilities, potential health benefits, wide variety of biological activities, and strong antioxidant qualities, phenolic compounds are substances that have drawn considerable attention in recent years. The main goal of the review is to draw attention to saharian Algerian medicinal plants and the determination of their bioactivity (antioxidant, anti-cancer, and anti-inflammatory importance), and to present their chemical composition as well as in vivo and in vitro studies, clinical studies, and other studies confirming their real impact on human health. Research results have revealed a rich variety of medicinal plants used to treat various disease states in this region. Based on in vivo and in vitro studies, biological activity, and clinical studies, a list of 34 species of desert plants, belonging to 20 botanical families, useful both in preventive actions and in the treatment of neoplastic diseases has been established, and polyphenolic compounds have been identified as key to the health potential of endemic diseases and desert plants. It has been shown that people who follow a diet rich in polyphenols are less prone to the risk of many cancers and chronic diseases, such as obesity and diabetes. In view of the increasing antioxidant potential of these plant species, as well as the increasing trade in herbal products from the Sahara region, phytosanitary and pharmaceutical regulations must change in this respect and should be in line with Trade Related Aspects of Intellectual Property Rights (TRIPS), and the sustainable use and development of plant products must be addressed at the same time.Item ABSORPTION REFRIGERATION SYSTEMS FOR WASTE HEAT RECOVERY AT THE SILICATE INDUSTRY(2024-01-01) Stoyanov Y.; Penkova N.; Krumov K.; Kassabov I.The glass, ceramic and cement plants are energy intensive industrial systems, releasing high amounts of greenhouse gases. The dissipation of the waste heat reduces their profitability, energy and ecological efficiency. The absorption refrigeration systems are successful solutions for the recovery of thermal energy at different temperature levels to obtain useful cooling and heating powers for technological needs, and for air conditioning of administrative and industrial buildings. Although the absorption units in a heat pump and refrigeration cycle are currently used in building and industrial systems, they have not yet penetrated widely into the silicate factories. This paper discusses possibilities for the applications of basic types of absorption cycles at heat pump and refrigeration modes to utilize waste energy at different temperature levels in glass, ceramic and cement plants. The examined variants are demonstrated via examples, diagrams and analyses of the possible energy saving.Item Biochemical Profile and In Vitro Therapeutic Properties of Two Euhalophytes, Halocnemum strobilaceum Pall. and Suaeda fruticosa (L.) Forske., Grown in the Sabkha Ecosystem in the Algerian Sahara(2023-04-01) Gheraissa N.; Chemsa A.E.; Cherrada N.; Erol E.; Elsharkawy E.R.; Ghemam-Amara D.; Zeghoud S.; Rebiai A.; Messaoudi M.; Sawicka B.; Atanassova M.; Abdel-Kader M.S.This study reports the biochemical profile and in vitro biological activities of the aerial part of two shrubs: Halocnemum strobilaceum and Suaeda fruticosa, a halophytes species native to saline habitats. The biomass was evaluated by determining its physiological properties and approximate composition. Hydro-methanolic extracts from Halocnemum strobilaceum and Suaeda fruticosa have been investigated for the inhibition of bacterial growth, the protection of proteins (albumin) from denaturation, and cytotoxicity to hepatocellular carcinomas (Huh-7 and HepG2). Their antioxidant activity was evaluated by five tests, including one that examined their ability to inhibit hydrogen peroxide (H2O2)-induced hemolysis. The profile of their phenolic compounds was also determined. These two euhalophytes had a high moisture content, high levels of photosynthetic pigments, elevated levels of ash and protein, low oxidative damage indices, MDA (Malondialdehyde) and proline, and low lipids levels. Their content was also characterized by a moderate acidity with good electrical conductivity. They contained abundant levels of phytochemicals and varied phenolic contents. Reverse phase high performance liquid chromatography (RP-HPLC) analysis revealed the presence of caffeic acid, p-coumaric acid, rutin, and quercetin in both plant extracts. On the pharmaceutical level, the two euhalophytes had anti-inflammatory, antibacterial, antioxidant, and cytotoxic properties, and therefore it was recommended to isolate and identify biologically active compounds from these plants and evaluate them in vivo.Item Conifers phytochemicals: A valuable forest with therapeutic potential(2021-01-01) Bhardwaj K.; Silva A.S.; Atanassova M.; Sharma R.; Nepovimova E.; Musilek K.; Sharma R.; Alghuthaymi M.A.; Dhanjal D.S.; Nicoletti M.; Sharma B.; Upadhyay N.K.; Cruz-Martins N.; Bhardwaj P.; Kuča K.Conifers have long been recognized for their therapeutic potential in different disorders. Alkaloids, terpenes and polyphenols are the most abundant naturally occurring phytochemicals in these plants. Here, we provide an overview of the phytochemistry and related commercial products obtained from conifers. The pharmacological actions of different phytochemicals present in conifers against bacterial and fungal infections, cancer, diabetes and cardiovascular diseases are also reviewed. Data obtained from experimental and clinical studies performed to date clearly underline that such compounds exert promising antioxidant effects, being able to inhibit cell damage, cancer growth, inflammation and the onset of neurodegenerative diseases. Therefore, an attempt has been made with the intent to highlight the importance of conifer-derived extracts for pharmacological purposes, with the support of relevant in vitro and in vivo experimental data. In short, this review comprehends the information published to date related to conifers’ phytochemicals and illustrates their potential role as drugs.Item SODA LIME SILICATE GLASSES CONTAINING IRON OXIDE - IN VITRO EVALUATION(2024-01-01) Mihailova I.; Harizanova R.; Shtapleva-Dimova N.; Georgiev H.; Nedkova-Shtipska M.Three glasses with different iron oxide concentrations (between 5 and 8.1 mol %) were obtained in the CaO - Na2O - SiO2 - Fe2O3 system by using conventional melting-quenching technique. The amorphous nature of the synthesized materials is confirmed by X-ray diffraction analysis, XRD. The physico-chemical and structural characterization of the glasses was performed by measuring their density, refractive indices, as well as by calculating the molar volume, oxygen packing density and recording the infrared spectra by Fourier Transformed Infrared Spectroscopy, FT-IR, respectively. The glasses were evaluated in vitro by examining bone-like apatite formation on their surfaces in a simulated body fluid, SBF. The structural changes in the glasses during the in-vitro test were traced by means of FT-IR and Scanning Electron Microscopy, SEM. The solutions were examined by Inductively Coupled Plasma Optical Emission Spectroscopy, ICP-OES to determine the ion exchange between the glasses and the starting SBF and the corresponding effect on the pH was also recorded.Item An Overview of Pomegranate Peel: A Waste Treasure for Antiviral Activity(2022-01-01) Hikal W.M.; Said-Al Ahl H.A.H.; Tkachenko K.G.; Mahmoud A.A.; Bratovcic A.; Hodžić S.; Atanassova M.Agricultural waste has always been a global problem that causes environmental pollution, and thanks to the efforts of scientists, this agricultural waste has become not a neglected product, but rather a source of many effective chemical compounds that have industrial, pharmaceutical and food applications. Viral disease therapy has attracted a great deal of scientific interest worldwide. Therefore, the pace of research is increasing for effective and safe treatment. The potential inhibitory activity of pomegranate peel extract polyphenols against virus for effective viral disease therapy has attracted a great deal of scientific interest. The aim of this review was to present an overview of the pomegranate peel effects on viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Influenza virus, Norovirus, Adenovirus, Herpes simplex virus, Coronavirus disease (COVID-19). Pomegranate is consumed as fresh fruit and juice for its reported health benefits as antioxidant, antidiabetic, hypolipidemic, antibacterial, anti-inflammatory, antiviral, anticarcinogenic activities, and improves cardiovascular as well as oral health. The health benefits of pomegranate have been attributed to its wide range of phytochemicals, which are predominantly polyphenols, ellagitannins, anthocyanins, and other polyphenols. Instead of the pomegranate peel being a neglected product, it is considered as a promising antiviral agent which also offers other health benefits without side effects.Item Lobularia libyca: Phytochemical Profiling, Antioxidant and Antimicrobial Activity Using In Vitro and In Silico Studies(2022-08-01) Benchikha N.; Chelalba I.; Debbeche H.; Messaoudi M.; Begaa S.; Larkem I.; Amara D.G.; Rebiai A.; Simal-Gandara J.; Sawicka B.; Atanassova M.; Youssef F.S.Lobularia libyca (L. libyca) is a traditional plant that is popular for its richness in phenolic compounds and flavonoids. The aim of this study was to comprehensively investigate the phytochemical profile by liquid chromatography, electrospray ionization and tandem mass spectrometry (LC-ESI-MS), the mineral contents and the biological properties of L. libyca methanol extract. L. libyca contains significant amounts of phenolic compounds and flavonoids. Thirteen compounds classified as flavonoids were identified. L. libyca is rich in nutrients such as Na, Fe and Ca. Moreover, the methanol extract of L. libyca showed significant antioxidant activity without cytotoxic activity on HCT116 cells (human colon cancer cell line) and HepG2 cells (human hepatoma), showing an inhibition zone of 13 mm in diameter. In silico studies showed that decanoic acid ethyl ester exhibited the best fit in β-lactamase and DNA gyrase active sites; meanwhile, oleic acid showed the best fit in reductase binding sites. Thus, it can be concluded that L. libyca can serve as a beneficial nutraceutical agent, owing to its significant antioxidant and antibacterial potential and due to its richness in iron, calcium and potassium, which are essential for maintaining a healthy lifestyle.Item Mineral Profile, Antioxidant, Anti-Inflammatory, Antibacterial, Anti-Urease and Anti-α-Amylase Activities of the Unripe Fruit Extracts of Pistacia atlantica(2023-01-01) Benmohamed M.; Guenane H.; Messaoudi M.; Zahnit W.; Egbuna C.; Sharifi-Rad M.; Chouh A.; Seghir B.B.; Rebiai A.; Boubekeur S.; Azli T.; Harrat M.; Sawicka B.; Atanassova M.; Yousfi M.Pistacia Atlantica in folk medicine is used by Algerian traditional healers for treating a wide variety of diseases and conditions including dyspepsia, digestive problems, peptic ulcers, and, in particular, inflammatory diseases. The present study aimed to assess the phytochemical composition, in vitro antioxidant activity (using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ABTS+, and reducing power methods), enzyme inhibitory activity (towards α-amylase and urease), antibacterial activity, and in vivo anti-inflammatory activity of the unripe fruit extracts of Pistacia atlantica collected from different parts of the Djelfa region of Algeria. According to the findings, various aqueous extracts exhibited significant antioxidant and enzymatic activities in all tests, but showed that they have a weak inhibitory effect against all tested bacterial strains. Twenty-one minerals comprising both macro- and microelements (Ba, Br, Ca, Cl, Co, Cr, Cs, Eu, Fe, K, Mg, Mn, Mo, Na, Rb, Sb, Sc, Sr, Th, U, and Zn) were determined using the technique of neutron activation analysis (INAA). The result indicates that the concentration of the mineral element is close to the minimal FAO recommendation. In addition, the result revealed significant anti-inflammatory activities. The data generated can be a valuable source of information for the pharmaceutical industry and medical research. These results suggest that the unripe fruit extracts of Pistacia atlantica have an appropriate potential to be utilized across a wide range of contexts as an agent with multifunctional uses, as well as a natural remedy for other physiological diseases.Item Effect of Juniperus communis extract on probiotic properties of Bacillus safensis isolated from camel milk in the region of El Oued (Algeria)(2024-09-01) Layadi I.; Laiche A.T.; Tlili M.L.; Messaoudi M.; Ghemam Amara D.; Mezghani-Khemakhem M.; Naccache C.; Sawicka B.; Atanassova M.; Zahnit W.; Ahmad S.F.The current study focuses on the effect of Juniperus communis extract on the probiotic properties of lactic acid bacteria isolated from camel milk in the region of El Oued (Algeria). Chromatographic analysis by HPLC was carried out to detect the most important compounds extracted from the plant. The total phenolic and flavonoid contents were determined using the colorimetric procedures Folin–Ciocalteu and aluminum chloride. The probiotic properties were studied and evaluated in vivo with Juniperus communis extracts after isolating strains from camel's milk and identifying them using 16S rRNA gene sequencing. Chromatographic profiles of the phenolic compounds revealed that Juniperus communis extract is rich in quercetin. After conducting chemical analyses of polyphenols and flavonoids, the results demonstrated a high content of phenolic compounds in Juniperus communis extracts (polyphenols: 103.80 ± 0.30 mg GAE/g E. flavonoids: 15.85 ± 0.80 mg QE/g E). Sequencing and phylogenetic analysis showed that the isolates belong to Bacillus pumilus and Bacillus safensis strains. The combination of Juniperus communis and Bacillus safensis restored the healthy intestine wall structure and returned the blood biochemical parameters to normal values. It was found that the mixture enhanced anti-inflammatory effectiveness by reducing erythrocyte sedimentation rate and C-reactive protein values. Juniperus communis has a high polyphenol and flavonoid content which can have a considerable impact on Bacillus safensis probiotic properties.Item Pirimicarb Induction of Behavioral Disorders and of Neurological and Reproductive Toxicities in Male Rats: Euphoric and Preventive Effects of Ephedra alata Monjauzeana(2023-03-01) Khattabi L.; Chettoum A.; Hemida H.; Boussebaa W.; Atanassova M.; Messaoudi M.Carbamate pesticides are a risk to human well-being, and pirimicarb is the most widely employed carbamate insecticide. This ongoing investigation aimed to reveal its toxicity on neurobehavioral and reproductive function. The study was carried out on male Wistar rats by assessment of behavioral changes via experiments, such as the forced swim test and the elevated plus maze; determination of oxidative stress (checking parameters such as catalase activity, etc.); measurement of cortisol and testosterone serum titers, and IL-1β levels in the plasma and brain; and evaluation of histopathological lesions that induced pirimicarb after 28 days of gavage, specifically in the brain and testis. Traces of pirimicarb were analyzed in tissue extracts using LCMS/MS. At the same time, the beneficial and protective effect of EamCE (Ephedra alata monjauzeana Crude Extract) were tested. The outcomes showed considerable anxiety and depressive status, with an evident increase in cortisol and IL-1β titers and an important decrease in oxidative enzymes and testosterone. Significant histological lesions were also recorded. In addition, the LCMS/MS analysis affirmed the accumulation of pirimicarb in organ tissue from rats force-fed with pirimicarb. Conversely, EamCE demonstrated outstanding potential as a preventive treatment, restoring cognitive and physical performance, boosting fertility, enhancing antioxidant and anti-inflammatory activities and preserving tissue integrity. We concluded that pirimicarb has critical deleterious impacts on health, affecting the neuroimmune-endocrine axis, and EamCE has a general euphoric and preventive effect.Item Quality Assessment of Medicinal Plants via Chemometric Exploration of Quantitative NMR Data: A Review(2022-06-01) Rebiai A.; Seghir B.B.; Hemmami H.; Zeghoud S.; Amor I.B.; Kouadri I.; Messaoudi M.; Pasdaran A.; Caruso G.; Sharma S.; Atanassova M.; Pohl P.Since ancient times, herbal medicines (HM) have played a vital role in worldwide healthcare systems. It is therefore critical that a thorough evaluation of the quality and control of its complicated chemical makeup be conducted, in order to ensure its efficacy and safety. The notion of HM chemical prints, which aim to acquire a full characterization of compound chemical matrices, has become one of the most persuasive techniques for HM quality evaluation during the last few decades. The link between NMR and chemometrics is discussed in this article. The chemometric latent variable technique has been shown to be extremely valuable in inductive studies of biological systems as well as in solving industrial challenges. The results of unsupervised data exploration utilizing main component analysis as well as the multivariate curve resolution, were various. On the other hand, many contemporary NMR applications in metabolomics and quality control are based on supervised regression or classification analyses.Item FT-IR AND RAMAN SPECTROSCOPY OF ZnO AND MgO CONTAINING GLASSES IN THE B2O3/Na2O/CaO/P2O5 SYSTEM(2024-01-01) Tasheva T.; Valova G.Glasses withcompositions 46.1B2O3-24.4Na2O-26.9CaO.2.6P2O5, xZnO/MgO-22.0B2O3-(24.4-x)Na2O-27CaO-2.5P2O5 (x = 2.5, 3 mol%) and 1.5ZnO-1.5MgO-22.0B2O3-21.5.Na2O-27CaO-2.5P2O5 were melted by melt quenching technique. The densities of the glasses were measured by the Archimedes principle, using an analytical scale. Glasses possess densities in the 2.538 to 2.623 g cm-1 range. The short-range order was also discussed from the molar volume Vm, cm3 mol-1, and oxygen packing density point of view. The molar volume of the glasses varies between 26.566 - 27.420 cm3 mol-1 and the oxygen packing density is between 73.669 to 76.262 mol cm-3. The Furie transform infrared spectroscopy and Raman spectroscopy were performed to study the main structural units constituting the structure of the samples. The main structural units were found to be BO3 and BO4 probably connected in pentaborate and triborate structural units. The influence of the ZnO and MgO on the structure and chemical bonding of the glasses was discussed.Item EFFECT OF GRINDING AIDS ON CEMENT PROPERTIES AND GRINDING PROCESS(2024-01-01) Popov A.; Chernev G.The cement industry is one of the most energy-intensive industries, which is why new energy-reducing and reducing CO2 emissions, additives are being sought. Grinding aid or grinding additives refer to substances that when mixed into the mill contents cause an increase in the rate of size reduction. These terms are very common in cement industries where it increases the throughput of the mill. Grinding aid also affects the cement flowability throughout the circuits. The grinding aid facilitates size reduction so that the mill has to apply less grinding power without hurting any of the properties of the resulting cement. The present research work aimed to investigate the influence of a chemical grinding aid ethylene glycol (EG) on cement properties and mill performance during the grinding of Portland cement beyond 500 ppm reaching up to 1200 ppm. The obtained results show increasing in initial compressive strength and increasing in the productivity of the cement mill.Item A COMPARATIVE STUDY OF THE SURFACE OF FACTORY AND HAND-MADE LOOPS ON TITANIUM-MOLYBDENUM ORTHODONTIC ARCHWIRE(2024-01-01) Yordanova R.The most important part of the brackets, used in orthodontic treatment, is the archwire, which, when activated, generate light and long-lasting biomechanical forces that make the teeth move. Different manufacturers offer ready-made expensive solutions for orthodontists - archwire with loops along the length of the wire of different shape, which increases the cost of treatment. However, orthodontic practice is strictly individual, depending on the patient’s orthodontic problems, the stages and methods of treatment. Orthodontists often have to choose between expensive archwires with pre-made loops or using an archwire that they can manually bend in the right places depending on the patient’s individual characteristics and specific needs. In this case, the orthodontist’s decision depends on preserving the quality of the archwire surface. The surface roughness of the orthodontic archwire plays an important role in the bracket-archwire complex and is an essential factor that determines the effectiveness of the guided movement of the teeth along the arch. Surface roughness not only affects the efficiency of sliding mechanics, due to frictional effects, but also corrosion behaviour and aesthetics. A comparison of the surface characteristics of Ti-Mo archwire - with factory and hand-made loops is made. The surface of the archwire in the bending zones of the loops was investigated by SEM analysis and Surface roughness analysis. The analysis of the results shows that manual bending practically does not change the surface of the archwire, does not introduce additional defects that increase the contact friction, as well as create conditions for faster deterioration of properties and the undesirable breakage of the archwire. Research results give orthodontists confidence that the manual bending process does not degrade the quality of the archwire surface. The hand-bent archwire preserves the possibility of trouble-free movement in the braces when tightening or loosening during the different stages of treatment.Item SYNTHESIS AND CHARACTERIZATION OF NANOPARTICLES FROM COAL FLY ASH(2024-01-01) Markov P.; Chernev G.; Nintianova D.; Kazakova N.; Karakostov H.In this study, amorphous nanoparticles were extracted from fly ash using a sol-gel method. The obtained nanoparticles were characterized using XRF spectroscopy, XRD, FT-IR and TEM. The XRD curves show the presence of both crystalline and amorphous phases. FT-IR analysis indicated the presence of silanol and siloxane groups. Upon analysis, the primary nanoparticles were found to exhibit a roughly spherical shape with an average size of approximately 65 nm. The findings of this study demonstrate the feasibility of applying the sol-gel method to synthesize nanoparticles derived from coal fly ash (CFA), thereby avoiding other expensive and energy-intensive methods of nanoparticle synthesis.Item Effect of In Vitro Pretreatment with Ag-Containing Amino Acid Nanofibers on Biometrics and Antioxidant Activity in Drought-Stressed Ex Vitro-Adapted Stevia rebaudiana Bertoni(2024-11-01) Miladinova-Georgieva K.; Sichanova M.; Petrova M.; Kirova E.; Nedev T.; Tsekova D.; Geneva M.Biotechnological methods prevent the destruction of natural populations of medicinal plants due to climate change and developing agriculture. This study evaluates the effects of in vitro pretreatment with two types of silver-containing amino acid nanofibers (NF-1%Ag and NF1-Ag salt) on the drought tolerance of ex vitro soil-adapted Steviia rebaudiana Bertoni. The duration of the drought was five days. The data suggested that the pretreatment with the studied nanofibers during plant propagation enhanced the plant tolerance to drought stress manifested in a smaller decrease in plant biomass accumulation and a smaller increase in sugar content. The pretreatment with the two tested nanoparticles of well-watered plants increased the leaf fresh biomass accumulation of the ex vitro-adapted S. rebaudiana compared to the untreated WW control plants. The highest values were reported at 10 mg L−1 NF1-Ag salt. Five days of drought led to a decrease in the leaf fresh biomass compared to the WW plants, with the recorded lowest reduction again at 10 mg L−1 NF1-Ag salt. These observations correlate with antioxidant activity improvement. The results show that adding 10 mg L−1 NF1-Ag salt to the MS medium led to higher ex vitro-adapted S. rebaudiana resistance to water deficit than 100 mg L−1. This paper discusses the impact of the selected nanofibers on parameters characterizing plant growth and antioxidant activity of drought-stressed ex vitro-adapted Stevia rebaudiana plants.