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Legure sa svojstvom pamćenja: Osobine, zahtevi i mogućnosti u inženjerskoj primeni: Prvi deo
No full textShape memory alloys (SMAs) are a subclass of shape memory materials (SMMs), which arematerials that, in response to a specific impact like thermal, mechanical, or magnetic changes,can "memorize" or hold into their prior form. This review addresses the properties, demands,and application prospects of SMAs, and provides a synopsis of recent advancements, as well asa historical background. Due to their special and exceptional qualities, SMAs have attracted alot of interest and attention recently in a wide range of commercial applications; basic andapplied research investigations have supported this commercial development. In order to shedlight on design, issues faced by SMA developers, this paper explains the characteristics of thesematerials that make them perfectly suited for variety of applications, addressing also theaccompanying constraints. This paper offers a pertinent overview of current SMA research.Legure sa svojstvom pamćenja (engl. shape memory alloys, SMA) su podgrupa velike familije „pametnih“ materijala, koji predstavljaju materijale koji posle spoljašnjeg uticaja koji može biti termički, mehanički i/ili magnetni, imaju osobinu da „memorišu“ ili zadrže prethodno stanje. U okviru ovog rada predmet interesovanja su svojstva, zahtevi za specifične primene, pregled skorašnjih istraživanja, kao i istorijski razvoj ove grupe materijala. Zahvaljujući svojim posebnim i izuzetnim svojstvima memorijske legure su u poslednje vreme privukle veliko interesovanje i pažnju u širokom spektru komercijalnih primena. Osnovna i primenjena istraživanja su podržala ova komercijalna interesovanja. Da bi se pojasnili izazovi sa kojima se suočavaju inženjeri koji se bave dizajnom ove grupe materijala, u okviru ovog rada su date karakteristike ovih legura koje ih čine veoma prikladnim za različite primene ali se rad istovremeno bavi i ograničenjima koja idu uz njih
Harnessing the hidden environmental power of Bjerkandera adusta laccase: Sustainable production, green immobilization, and eco-friendly decolorization of mixed azo dyes
No full textThis research unveils the untapped potential of laccase, derived from the Bjerkandera genus, utilizing it in an immobilized system aimed at detoxifying harmful azo dye effluents from the textile industry, thus contributing to environmental protection. Marking a pioneering achievement, we recorded the highest laccase activity at 94.52 U/g cultivating B. adusta's mycelium on brewer's spent grain, enhanced with lignocellulosic waste, under meticulously optimized conditions −2.69 g of alkali-pretreated beech sawdust, 0.91 g of cypress cone, and 8-day incubation period. The harvested laccase was subjected to an immobilization process on alkali-pretreated beech sawdust, where, through optimization, we established the ideal conditions (30 mg of carrier, pH 7, and 3.5 h), achieving an immobilization efficiency of 72.24% with a residual activity of 57.64%. Remarkably, both free and immobilized forms of the B. adusta TMF1 laccase enzyme demonstrated formidable efficacy in decolorizing a mix of three distinct azo dyes (Orange G, Eriochrome Black T, and Congo Red), eliminating over 63% of the coloration within just 30 min. The immobilized laccase showed consistent performance across four decolorization cycles. Moreover, the breakdown products of the azo dye mix were analyzed using the HPLC method, complemented by evaluations of potential antimicrobial activity, phytotoxicity and cytotoxicity, revealing a non-toxic composition without cytotoxicity, highlighting the process's safety for environmental release. The significance of this research is reflected in the distinguished construction of a green biocatalyst acting as a stable and time-efficient in remediation of targeted azo dye pollution from the textile industry following the principles of circular economy
Starch aerogels properties influenced by the addition of sodium alginate with and without cross-linker calcium chloride
No full textThis work investigated the synthesis and properties of starch/alginate aerogels. Synthesis of
starch/aerogel blends was performed from aqueous suspensions with different starch and
alginate contents (0, 3, 5, 7, and 10% w/w). Each starting aqueous suspension contained 10%
w/w of biopolymers and hydrogels were formed by stirring on a magnetic stirrer for 3 h at
95 ºC. During water replacement with ethanol, alcogels were formed with and without crosslinker calcium chloride. Finally, the drying of alcogels was performed with supercritical CO2
at 100 bar and 45 ºC for two cycles of static (1 h) and dynamic (20 min) regimes. The influence
of alginate content, cross-linker addition, and ethanol concentration on aerogel properties
was evaluated by BET isotherms, FESEM, and TGA/DSC. It was found that the addition of
calcium chloride led to a decrease in the specific surface area of aerogels. The solvent
exchange remains the greatest cause for aerogel pore shrinkage and it was confirmed that
gradual solvent exchange is superior compared to the fast exchange. Thermograms for all
samples exhibited a similar pattern, regardless of the presence of crosslinker, with two stages
of weight loss
Alginate/chitosan aerogels synthesis and characterization
No full textIn this work synthesis and characterization of alginate/chitosan aerogels was studied. 4 and
5% (w/w) alginate solutions were prepared by dissolving a weighted amount of Na-alginate
in distilled water, while in the case of chitosan, 2% solution (w/w) was prepared in 1 M
CH3COOH. The solutions were mixed in alginate/chitosan mass ratios of 1:1 and 10:1 and
stirred overnight on a magnetic stirrer to form the hydrogel, which was further transferred
into petri dishes. Also, hydrogels were formed from pure alginate (4 and 5% (w/w) solutions)
for comparison. All hydrogels were treated with 5% calcium chloride solution to promote
gelation. Complete replacement of water with ethanol was performed during several days by
successive increase of its concentration until 100%. Drying of obtained alcogels was
performed using scCO2 at two temperatures (45 and 55 °C) and pressures (10 and 15 MPa)
to obtain aerogel. The textural properties of aerogels were determined by N2 adsorptiondesorption analysis morphological characteristics by FE-SEM, presence and interaction of
characteristic functional groups by FTIR spectroscopy and porosity using the water
displacement method. The results revealed that all aerogels were mesoporous with porosity
over 90% and the specific surface area up to 447 m2/g. The increasing weight ratio of chitosan
in the aerogels influenced the textural and morphological properties of the aerogel and led to
a lower specific surface area, higher diameter of mesopores and thicker fibres of the porous
network
Novel chitosan and N-isopropylacrylamide-grafted-dextran-based microformulations as effective oral drug delivery system
No full textNovel polymer network microformulations have been widely used for pharmaceutical applications. Especially challenging is to design and develop an ideal oral drug formulation due to many hostile factors in gastrointestinal (GI) tract microenvironment. Hydrogels attained striking attention for the use in controlled drug delivery systems, and for that purpose temperature- and pH-sensitive hydrogels have been extensively employed. This paper reports synthesis and characterization of innovative polymers-crosslinked hydrogel system consisted of N-isopropylacrylamide-graft-dextran (NiPAAm-g-Dex) and chitosan (Ch). Composition of the system was optimized to demonstrate distinguished encapsulation efficiency (EE) and release properties of diclofenac sodium (DS). The microspheres structure and morphology were confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR) and scanning electron microscopy (SEM), respectively. Prepared microparticles have successfully passed through the simulated gastric and small intestine and reached the intestine, where the release of DS was carried out. In vitro release studies showed smooth release profile in a controllable manner with up to 40% release of the model drug after 4 h at pH 7.20 ± 0.01. Based on the results, novel polymer microformulations show excellent potential as controlled release drug delivery system and represent a superb candidate for additional in vivo testing
Supplementary material for the article: Vesković, J., Sentić, M.,& Onjia, A.. (2024). Hydrogeochemical Facies and Health Hazards of Fluoride and Nitrate in Groundwater of a Lithium Ore Deposit Basin. Metals, 14(9), 1062. https://doi.org/10.3390/met14091062
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.Related to: [https://technorep.tmf.bg.ac.rs/handle/123456789/7647]Supplementary material for: [https://doi.org/10.3390/met14091062
Assessment of Enzymatically Derived Blackcurrant Extract as Cosmetic Ingredient—Antioxidant Properties Determination and In Vitro Diffusion Study
No full textBlackcurrant is an anthocyanin-rich berry with proven antioxidant and photoprotective activity and emerging prebiotic potential, widely applied in cosmetic products. Hereby, highly efficient enzyme-assisted extraction of blackcurrant polyphenols was performed, giving extract with very high antioxidant activity. Obtained extract was characterized in terms of anthocyanin composition, incorporated into three different cosmetic formulations and subjected to Franz cell diffusion study. Experimental values obtained using cellulose acetate membrane for all four dominant anthocyanins (delphinidin 3-glucoside, delphinidin 3-rutinoside, cyanidin 3-glucoside and cyanidin 3-rutinoside) were successfully fitted with the Korsmeyer–Peppas diffusion model. Calculated effective diffusion coefficients were higher for hydrogel compared to oil-in-water cream gel and oil-in-water emulsion, whereas the highest value was determined for cyanidin 3-rutinoside. On the other hand, after a 72 h long experiment with transdermal skin diffusion model (Strat-M® membrane), no anthocyanins were detected in the receptor fluid, and only 0.5% of the initial quantity from the donor compartment was extracted from the membrane itself after experiment with hydrogel. Present study revealed that hydrogel is a suitable carrier system for the topical delivery of blackcurrant anthocyanins, while dermal and transdermal delivery of these molecules is very limited, which implies its applicability for treatments targeting skin surface (i.e., prebiotic, photoprotective)
High-performance hydrophilic separators for supercapacitors based on alkali-modified cellulose nanocrystal aerogels
No full textThe shift towards low-carbon technologies is driving an increasing demand for energy
conversion and storage systems like supercapacitors, batteries and fuel cells. Therefore, it is
crucial to replace traditional materials with renewable and high-performance alternatives. This
research introduces a novel approach of designing and fabricating high-performance
conductive separators for supercapacitors, leveraging the interaction between alkali ions and
highly crystalline nanocellulose (CNC), the most abundant biopolymer. The modified CNC with
potassium ions exhibits exceptional performance, surpassing commercial glass microfiber
separators in terms of mechanical properties and ionic conductivity. The hydrophilicity and high
porosity facilitate efficient potassium ion transport, as demonstrated in supercapacitor devices.
By integrating rehydrated conductive separators between glucose-derived mesoporous carbon
electrodes, the supercapacitor device achieves high specific capacitance of 80 F/g at 10 mV/s
in Swagelok cells and capacitance retention of 95% over 1000 consecutive cycles. These results
highlight the potential of these innovative materials to serve as safe and high-performance
components in renewable energy storage devices
New protective coatings based on pyrophyllite and zirconium silicate
No full textThe paper presents the results of the synthesis and characterization of refractory coatings based
on pyrophyllite (80%) and zirconium silicate (20%) with a binder based on epoxy resin intended
for the protection of metal and non-metal constructions and parts of equipment in industry.
Samples of refractory fillers were subjected to micronizing grinding to the filler grain size:
pyrophyllite 20μm and zirconium silicate 15μm. This achieved a good alignment of the filler
particles with each other. XRD, SEM, and optical microscopy methods were used to characterize
the obtained fillers. The optimal composition of protective coatings and the procedures for their
production were determined by testing. The ultrasonic vibration method with a stationary sample
according to the ASTM G32 standard was used to characterize the obtained coatings. The aim of
the test was to determine the quality of the coating and the possibility of application for the
protection of metal surfaces in conditions of wear, corrosion, cavitation, and elevated
temperatures. The quality of the coating was evaluated based on the value of the cavitation speed
and the analysis of the formation and development of damage to the surface of the samples under
the effect of cavitation. Based on the measurement of mass loss during the test under the effect of
cavitation, the cavitation speed was determined (V = 0.31 mg/min), and the morphology of the
damaged surfaces was analyzed by recording the surface of the coating on a scanning electron
microscope. It was established that mass losses and the formation of pits on the surface of the
coating were small and that the surface damage was 16.5%, which shows that the tested coating
samples have satisfactory cavitation resistance. The tested coatings based on pyrophyllite and
zirconium silicate can be applied to protect metallic surfaces in conditions where moderate
cavitation effects are expected
Electrochemically synthesized biomaterials
No full textElectrochemical methods were employed for synthesizing composites intended for applications in
medicine as antibacterial coatings on titanium bone implants or as highly efficient antibacterial hydrogels for
accelerated wound healing.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202