8639 research outputs found
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Tehnološki postupak za dobijanje antimikrobnih aerogelova skroba
No full textPredloženo tehničko rešenje opisuje tehnološki postupak za dobijanje antimikrobnih aerogelova skroba. Bioaktivni materijala su proizvedeni primenom ekološki prihvatljivih tehnika upotrebom zelenog medujuma (natkritičnog ugljen(IV)-oksida), biokompatibilnih i biorazgradivih materijala iz obnovljivih izvora i prirodnih bioaktivnih jedinjenja. Zeleni medijum se u potpunosti uklanja iz finalnog proizvoda i može se reciklirati nakon proizvodnje. Proizvedeni aerogelovi skroba sa timolom, eugenolom, karvakrolom i citronelolom (12,815,8 mass%) pokazuju jaku antimikrobnu aktivnost. Dobijeni aerogelovi se mogu upotrebiti u medicini za tretiranje inficiranih rana jer apsorbuju do 265 do 569% okolne tečnosti i inhibiraju rast Gram-negativnih bakterija, Gram-pozitivnih bakterija i gljivica (veličina prečnika zone inhibicije je do 37,5 mm). Predmetno tehničko rešenje pokazuje obećavajući zeleni pristup za proizvodnju bioaktivnih dvokomponentnih materijala na bazi skroba za potencijalnu primenu u lečenju infekcija kože. Ovim rešenjem prevazilaze se ekološki problemi stvaranja otpada prilikom proizvodnje bioaktivnih materijala i korišćenjem proizvedenog materijala izbegava se akumulacija otpada nakon upotrebe.Tehničko rešenje kategorije M85 - Novo tehničko rešenje (nije nekomercijalizovano
An Eco-Friendly Supercritical CO2 Recovery of Value-Added Extracts from Olea europaea Leaves
No full textAn eco-friendly approach towards the recovery of value-added extracts from olive tree leaves with the aid of supercritical CO2 at 30 MPa was carried out. The impact of extraction temperature (35–90 °C) and presence of co-solvents (ethanol, water, and aqueous ethanol) on the total phenolic, flavonoid, and pigment content, as well as oleuropein, hydroxytyrosol, tyrosol, and α-tocopherol content was determined. In addition, the antioxidant activity of extracts from tree leaves using DPPH, ABTS, and CUPRAC assays was investigated. The results of the study showed that the most effective supercritical CO2 extraction was at 90 °C with an addition of ethanol, which enabled the separation of extract with the highest content of tested compounds. Some of the highest recorded values were for oleuropein 1.9 mg/g, for carotenoids 5.3 mg/g, and for α-tocopherol 2.0 mg/g. Our results are expected to contribute to the efforts towards the valorization of olive leaves as a sustainable source of valuable compounds, and boost local economies as well as the interest of pharmaceutical, food, and cosmetic industries for novel food by-product applications
Production of Micro Nanofibrillated Cellulose from Prerefined Fiber via a Dry Dielectric Barrier Discharge (DBD) Oxygen Plasma-Treated Powder Precursor
No full textCellulose is a strong contender for the development of sustainably resourced biodegradable material composites supporting circular economy. Nanofibrillar cellulose-comprising materials are among the most promising lignocellulose derivatives. Currently, their production capacity and economy are hindered by high chemical and energy consumption, the latter primarily during mechanical fibrillation of native fiber in aqueous suspension and the negative limitation of very low solid content associated with the gel-like properties of the resulting final product. The application of oxygen gas barrier discharge (DBD) plasma on dry cellulose fiber, as reported here, is considered novel in achieving onward nanofibrillation. At this early stage, though, simple laboratory DBD equipment precludes the study of overall efficiency. Example fiber was taken from paper pulp manufacture but may not be limited to wood source. The oxygen plasma was seen to etch the microcellulose fiber structure, simultaneously oxidizing the glue-functioning hemicellulose, rendering it soluble, so that nanopolymer crystalline-based cellulose fibrils can be readily released at the surface of the host refined microfiber at the point of application, forming micro nanofibrillated cellulose structure (MNFC) at previously uneconomic higher solid content. Eliminating the need for liquid water during precursor process treatment is considered potentially transformative with respect to production feasibility, end-product transportation and application.纤维素是开发支持循环经济的可持续资源可生物降解材料复合材料的有力竞争者. 含纳米纤维纤维素的材料是最有前景的木质纤维素衍生物之一. 目前，它们的生产能力和经济性受到高化学和能源消耗的阻碍，后者主要是在水悬浮液中天然纤维的机械原纤化过程中，以及与最终产品的凝胶状特性相关的极低固体含量的负面限制. 如本文所述，氧气阻挡放电（DBD）等离子体在干纤维素纤维上的应用被认为是实现向前纳米纤维化的新方法. 然而，在这个早期阶段，简单的实验室DBD设备阻碍了对整体效率的研究. 示例纤维取自纸浆制造，但可能不限于木材来源. 观察到氧等离子体蚀刻微孔纤维素纤维结构，同时氧化起胶作用的半纤维素，使其可溶，从 而在应用点，纳米聚合物结晶基纤维素原纤维可以很容易地在宿主精制微纤维的表面释放，在以前不经济的较高固体含量下形成微纳米纤维化纤维素结构（MNFC）. 在前体工艺处理过程中消除对液态水的需求被认为在生产可行性、最终产品运输和应用方面具有潜在的变革性
Moving Towards a Holistic Approach to Circular Cities: Obstacles and Perspectives for Implementation of Nature-Based Solutions in Europe
No full textNature-based solutions (NBS) are frequently implemented without taking the system’s perspective into account and with the main focus on technical and economic issues of implementation. This study was conducted to test the hypothesis on the potential synergistic effects between circularity and NBS to holistically tackle urban challenges. The main objective is to establish preliminary insights on the obstacles and perspectives of NBS integration and implementation, through a questionnaire set up by the network of experts gathered within the COST Action CA17133 Circular City. The following research questions arise: (i) what differences exist in the level of NBS application according to the variance of engaged countries; and (ii) what are the main obstacles and perspectives for the NBS implementation in order to holistically tackle urban challenges, enhancing the sustainable connection among urban environment, nature, and human well-being. To go beyond the current state-of-the-art and reflect on the research conducted within the Circular City Action, this study aims to open a multi-geographical academic dialogue across Europe and beyond and to move towards a holistic approach to circular cities. Accordingly, this study is: (1) multi-geographical and context-based, providing input for thirty-three EU countries and four non-EU countries to give an overview of the main obstacles and perspectives of NBS implementation, and (2) approach-directed, aiming to formulate a holistic approach to deal with societal challenges. This document intends to provide qualitative and quantitative insight into the potentials and obstacles of NBS implementation in Europe, as well as to motivate further discussion and research to achieve holistic and sustainable citie
Synthesis and Antimicrobial Activity of Newly Synthesized Nicotinamides
No full textAntioxidants are promising compounds with antimicrobial activity against drug-resistant pathogens, especially when combined with conventional antimicrobials. Our study aimed to characterize the structure of nicotinamides synthesized from nicotinic acid and thiocarbohydrazones and to evaluate their antibacterial and antifungal activity. Seven nicotinic acid hydrazides (NC 1–7) were synthesized using mono-thiocarbohydrazones with hydroxyl group substituents, along with quinolone, phenolic, and pyridine rings known for their antimicrobial activity. The in vitro antimicrobial activity of NC 1–7, at concentrations ranging from 0.001 to 1 mM, was tested against Staphylococcus aureus (ATCC 6538), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853), Klebsiella pneumoniae (NCIMB 9111), and Candida albicans (ATCC 24433) using the broth microdilution method per EUCAST 2024 guidelines. Microorganism survival percentages were calculated based on optical density, and target fishing using the PharmMapper database identified potential molecular targets. The results showed that P. aeruginosa was most susceptible to the compounds, while C. albicans was the least susceptible. NC 3 significantly inhibited P. aeruginosa and K. pneumoniae growth at 0.016 mM, while higher concentrations were required for S. aureus, E. faecalis, and C. albicans. NC 5 was most effective against gram-positive bacteria at 0.03 mM. Only NC 4 completely inhibited C. albicans below 1 mM. NC 3, with the lowest concentration for 50% growth inhibition (0.016–0.064 mM), showed promising antibacterial potential against specific AMR-related proteins (bleomycin resistance protein, HTH-type transcriptional regulator QacR, and streptogramin A acetyltransferase), suggesting that this class of compounds could enhance or restore the activity of established antibiotics
ATMOSPHERIC PRESSURE PLASMA IN PROCESSING OF CELLULOSE FIBERS
No full textPlasma processing of textile materials, especially ones from natural and
chemical cellulose fibers, has been the focus of many researchers in the past
three decades (1, 2). Plasma treatments, as an alternative to conventional wet
treatments in textile processing, such as dewaxing, scouring, bleaching,
extraction etc., used to clean fiber surfaces or to tailor fiber surface chemistry
and morphology, have many advantages, such are low energy, chemical and
water consumption, and short time of treatment, which makes this process
environmentally friendly.
Among many different plasma configurations available, which can be
classified according to several criteria, such as the type of energy supply (direct
or alternating with different frequencies), temperature (hot (thermal) and cold
(non-thermal) plasma), and pressure (low-pressure and atmospheric pressure
plasma), atmospheric pressure plasma, especially dielectric barrier discharge
(DBD), is highly promising for textile material modification thanks to its simple
arrangements and adaptability of electrodes' shape, more homogeneous surface
discharge with lower temperature electrons preventing localized overheating and
damage of treated material as well as its potential for up-scaling and
implementation in existing industrial facilities (DBD parameters optimized in
laboratory conditions can be easily transferred to industrial conditions) and
continuous textile processing (1).
In this paper, we present a comparative study on the functionalization of
natural (cotton and jute) and chemical (viscose) cellulose fibers by DBD
treatment with special emphasis on the aging effect as an additional treatment
parameter. By controlling the DBD variables, such as the nature of gas (air,
oxygen, and nitrogen), discharge power, frequency, and exposure time, a great
variety of surface effects can be achieved, such as surface cleaning and etching,
introduction of new functional groups, increase or decrease surface energy,
cross-linking, etc
In vitro assessment of skin permeation properties of enzymatically derived oil-based fatty acid esters of vitamin C
No full textCurrent topical formulations containing vitamin C face limitations in therapeutic effectiveness due to the skin's selective properties that impede drug deposition. Consequently, the widespread use of toxic and irritating chemical permeation enhancers is common. Hereby, we investigated enzymatically derived fatty acid ascorbyl esters (FAAEs) obtained using natural oils for their skin permeation properties using the Strat-M® skin model in a Franz cell diffusion study. By evaluating various cosmetic formulations without added enhancers, we found that emulgel is most suitable for enhancing the cutaneous and transdermal delivery of FAAEs. Furthermore, medium-chain coconut oil-derived FAAEs exhibited faster diffusion rates compared to sunflower oil-based FAAEs with long-side acyl residues, including the commonly applied ascorbyl palmitate. Experimental data were successfully fitted using the Peppas and Sahlin model, which accounted for a lag phase and the combined effect of Fickian diffusion and polymer relaxation. In the case of long-chain esters, the lag phase was prolonged, and the calculated effective diffusion coefficients (Deff) were lower compared to medium-chain FAAEs. Accordingly, the highest Deff value was observed for ascorbyl caprylate, being even 60 times higher than for ascorbyl palmitate. These results suggest the emerging potential of emulgel with incorporated coconut oil-derived FAAEs for efficiently delivering vitamin C into the skin
Interface Engineering in Perovskite Solar Cells: The Role of Halogen Bonding
No full textHigh power conversion efficiencies and excellent optoelectronic properties have made
hybrid halide perovskites attractive for photovoltaic applications [1,2]. On the other hand, the
applications of these materials are hindered by their rather poor stability under operating conditions [3]these efforts have focused on perovskite materials design, which increasingly relies on
molecular modulators that engage in halogen bonding, a uniquely directional noncovalent (supramolecular. Most instabilities stem from ion migration at the interfaces with charge transport
layers within the photovoltaic cell [2]. One of the strategies to mitigate this issue is interfacial
engineering through supramolecular modulators, with halogen bonding (XB) being a promising candidate [4]. As charge transport layers in these devices are usually metal oxides, XB has
the propensity to improve operational stability as well as charge transfer [3]these efforts have
focused on perovskite materials design, which increasingly relies on molecular modulators
that engage in halogen bonding, a uniquely directional noncovalent (supramolecular. This type
of modulation can act as a barrier for incoming ions, suppressing their migration, improving
hydrophobicity, and affecting photovoltaic characteristics [5]. We have applied 1,4-diiodotetrafluorobenzene (TFDIB) as an XB agent at the TiO2
/perovskite interface within the conventional n-i-p perovskite solar cell devices [6]. Structural and optoelectronic properties have been
characterized by a combination of techniques, including scanning electron microscopy, X-ray
diffraction, UV-Vis absorption, and photoluminescence spectroscopy, to identify interfacial
changes upon XB. As a result, we have demonstrated the improvement of operational stability
in perovskite solar cells, providing a versatile supramolecular strategy in such hybrid energy
conversion devices
Hydrogeochemical Facies and Health Hazards of Fluoride and Nitrate in Groundwater of a Lithium Ore Deposit Basin
No full textFluoride and nitrate contamination in groundwater is a global concern due to their toxicity
and associated negative health effects. This study incorporated a comprehensive methodology,
including hydrogeochemical analysis, drinking and irrigation water quality assessment, source
apportionment, and health risk estimation of groundwater fluoride and nitrate in a lithium ore
deposit basin in western Serbia. Groundwater major ion hydrogeochemistry was governed by water–
rock interactions, with Ca-Mg-HCO3 identified as the predominant groundwater type. The entropyweighted water quality index (EWQI), sodium adsorption ratio (SAR), and sodium percentage (%Na)
revealed that 95% of the samples were of excellent to good quality for both drinking and irrigation.
Moreover, the results showed that fluorides were of geogenic origin, whereas nitrates originated from
agricultural activities. Although the fluoride and nitrate levels in groundwater were relatively low,
averaging 1.0 mg/L and 11.1 mg/L, respectively, the results of the health risk assessment revealed
that the ingestion of such groundwater can still lead to non-cancerous diseases. The threshold of
one for the hazard index was exceeded in 15% and 35% of the samples for adults and children,
respectively. Children were more vulnerable to non-carcinogenic risk, with fluorides being the
primary contributing factor. The study outcomes can serve as a reference for other lithium-bearing
ore areas and guide the management of regional groundwater resources.Supplementary information: [https://technorep.tmf.bg.ac.rs/handle/123456789/7651
Sustainable approach to raw clays for ceramic and refractory applications: insights from updated traditional ternary diagrams
No full textThe study analysed 93 samples from four Serbian clay deposits to determine their suitability for ceramics production. The samples were mainly composed of illite and kaolinite. Ternary diagrams were used to classify the samples and evaluate their applicability. Winkler's diagrams, ternary graphs and mineralogical compositions were analysed. The results showed a broader area in these graphs than previously determined for structural ceramics, as well as the potential of these clays for ceramic production. The study used dry-milled, hydraulically semi-dry, pressed and fired samples to assess water absorption and flexural strength and statistical analysis to determine the key parameters influencing final product quality, including that of refractory, wall and floor tiles. This paper evaluates the raw clay materials' applicability in ceramic production, promoting sustainable use through rapid initial tests, energy savings through dry milling and ecologically sound principles through resource-efficient evaluation