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Poređenje tamnih i mlečnih kakao preliva proizvedenih uz upotrebu petovaljka i kugličnog mlina
No full textChocolate toppings are confectionery products comprised of non-fat dark cocoa solids and sugar particles dispersed in cocoa butter, as a continual matrix. On the other hand, dark cocoa toppings contain cocoa powder and sugar dispersed in vegetable fat that is cheaper than cocoa butter, but with adequate characteristics. Also, with the addition of a 7% non-fat milk fraction, this product is regarded as a milk cocoa topping. This kind of product, dark and milk cocoa toppings, does not demand long-term conching or tempering. This study aimed to determine and compare the impact of the production process on rheology, particle size distribution and content of moisture, fats, sucrose and lactose. Based on the rheology properties, it was found that the values of the Casson and linear viscosity of the samples produced using a five-roll mill and conching were lower compared to those produced using a ball mill. Regarding particle size distribution, the results showed that the volume-weighted mean parameter D (4,3) was lower for the milk and dark cocoa confectionery topping produced in the ball mill. Additionally, the values of the yield stress in samples produced in the ball mill were 2-fold higher for the milk cocoa topping and 4.5-fold higher for the dark cocoa topping compared with the values of the samples produced using the five-roll mill and conching. The near-infrared spectroscopy (NIRS) analysis did not show any significant difference among the samples. It can be concluded that the difference between the samples produced in the ball mill and the five-roll mill and conching exists and that the ball mill can be used for the production of high-quality cocoa toppings thus providing a shorter time of production.Čokoladni prelivi su konditorski proizvodi koji se sastoje od nemasnih tamnih kakao delova i čestica šećera dispergovanih u kakao puteru, kao kontinualnoj fazi. S druge strane, tamni kakao prelivi sadrže kakao prah i šećer dispergovan u biljnoj masti koja je jeftinija od kakao putera, ali sa adekvatnim karakteristikama. Takođe, sa dodatkom 7% nemasne frakcije mleka, ovaj proizvod se smatra mlečnim kakao prelivom. Ovakvi proizvodi (tamni i mlečni kakao preliv) ne zahtevaju dugotrajno končiranje ili temperiranje. Ovaj rad je imao za cilj da utvrdi i uporedi uticaj procesa proizvodnje na reologiju, distribuciju veličine čestica i sadržaj vlage, masti, saharoze i laktoze u kakao prelivima. Na osnovu reoloških svojstava, utvrđeno je da su vrednosti Casson i linearnog viskoziteta uzoraka proizvedenih u mlinu sa pet valjaka i uz končiranje bile niže u odnosu na one vrednosti viskoziteteta uzoraka proizvedenih u kugličnom mlinu. Što se tiče distribucije veličine čestica, rezultati su pokazali da je zapreminsko-maseni srednji parametar D (4,3) bio manji za mlečni i tamni kakao preliv, proizveden u kugličnom mlinu. Pored toga, vrednosti prinosnog napona u uzorcima proizvedenim u kugličnom mlinu bile su 2 puta veće za mlečni kakao preliv i 4,5 puta više za tamni kakao preliv u poređenju sa vrednostima uzoraka proizvedenih upotrebom petovaljka i končiranja. Analiza bliske infracrvene spektroskopije (NIRS) nije pokazala značajnu razliku u sadržaju masti, saharoze i laktoze između uzoraka. Može se zaključiti da razlika između uzoraka proizvedenih u kugličnom mlinu i petovaljku postoji i da se kuglični mlin može koristiti za proizvodnju visokokvalitetnih kakao preliva, čime se obezbeđuje kraće vreme proizvodnje
Structure–property correlations for composite hydrogels based on poly(methacrylic acid) and high concentrations of LTA zeolite
No full textHigh concentrations of LTA zeolite (27-52mass%) were embedded in poly(methacrylic acid) (PMAA) matrix to obtain composite hydrogels with porosity and active sites originating from both components. Substandard mechanics of PMAA and aggregation of zeolite particles, were thereby overcome. The composites had remarkably higher density than PMAA xerogel (1700 to1400 kg m−3), higher crosslinking density (54.8 to1.29 mol m−3) and lower swelling degree (41 to 420 kg kg−1). Zeolite particles were uniformly dispersed in PMAA matrix and there was no agglomeration or leaching of zeolite despite very high concentrations. XRD patterns revealed that the inclusion of zeolite particles affected the short-range order in the PMAA matrix. Being an active filler LTA zeolite notably improved thermal stability and mechanics of PMAA hydrogel, multiplying the storage modulus 5.2 times in dry and 21.8 times in swollen state. Structure–property correlations were provided making the base for further development of tailor-made zeolite-PMAA composite hydrogels
Biocharacterization of hydrogels based on poly(methacrylic acid) prepared by eco-friendly method
Get PDFINTRODUCTION: Inflammation process in human body can lead to many serious inflammation-related diseases. Hence, there are urge to find better solution for the treatment of the inflammation processes. Solution can be found in application ofpoly(methacrylicacid) hydrogels which have potential for targeted delivery and controlled release of drugs. These pH-sensitive hydrogelscan swell at the pH values between 5 and 8,and release drug in the process. So,taking into account that pH value at the inflammation site is around 6, these hydrogels are materials of choice. It is very important thatthe system for controlled releasebe prepared through mild and non-toxic conditions in order to preserve bioactivity of the drug andkeep good impact on environment. Enzymes are good candidates for eco-friendly preparation of hydrogels, because these greensubstancescan initiate polymerisation of various monomers.
EXPERIMENTAL (or Materials and Methods):In this study, hydrogels based on poly(methacrylic acid) were prepared through eco-friendly method by using enzyme/hydrogen peroxide(HP)/ascorbic acid(AA)as initiator. Two groupsof the samples were prepared: in the first group peroxidase isolated from potato peel waste (with activity of 0.8 IU) was used in the initiation system, whereas in the second group peroxidase isolated from soya bean coats (with activity of 0.8 IU) was employed in the initiation system. The amounts of HPand AAin both series were 40 μL and 10 mg, respectively.Anti-inflammatory drugs,dexamethasone(5 mg/mL)and diclofenac(4.5 mg/mL)were encapsulated in the first and the second group of the PMAA samples, respectively. Anti-inflammatory effect of the PMAA hydrogels with encapsulated drugs were tested on the Bovine Chondrocytes cells.
RESULTS AND DISCUSSION:Results showed that the level of pro-inflammatory mediators NO and IL-8 decreased. The PCR analysis showed that the proinflammatory TNα, IL-6 genesexpression level decreased, the matrix catabolism MMP1and MMP3 genesexpression level decreased and the fibrotic COL2 and ACAN genes expression level increased.
CONCLUSIONS:The studyshowed that the PMAA hydrogels have anti-inflammatory effect and have potential for treatment of the inflammation processes.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202
Environmentally friendly hydrogels for medical and pharmaceutical applications
Get PDFThe Polymer group of the Faculty of Technology and Metallurgy University of Belgrade deals with environment-sensitive hydrogel as carriersfor biomedical applications, including drug delivery, wound healing, and regenerative medicine. The first hydrogel generation synthesized in our labs was discs made of polyacrylamide and its derivatives. The synthesis was at higher temperatures (50 °C), with traditional crosslinker, N, N’-methylenebisacrylamide, and persulphate/pyrosulphate as initiator. Due to the growing demands for environmental sustainability, the general approach changed to reduce petrochemical raw materials and prepare eco-friendly materials focusing on 1) renewable polymers, initiators, and crosslinkers and 2) the application of simple, cost-effective, and eco-friendly approaches in hydrogel synthesis. To obtain the second hydrogel generation, we use renewable polymers: polysaccharides, proteins, and polyhydroxyalkanoates [1]. Still, the mechanical strength was weak. Hence, the applicationof carboxylic acids, methacrylic and itaconic, and N-isopropyl acrylamide improves mechanical properties and enhances the environmental stimuli of the carriers. Instead of traditional crosslinkers -organic molecules, we gave the advantage to plant extracts like genipin, sodium tripolyphosphate, citric acid, and calcium chloride. We made beads, microgels, aerogels, discs, films, and cylinders sensitive to pH, temperature, magnetic field, or specific molecules such as glucose. Facing an everyday challenge, improving drug delivery routes, especially for poorly water-soluble drugs, and finding an alternative to traditional antibiotics, encapsulation, and controlled release remain a challenge. Therefore, we used a mild condition (e.g., deep coating) to encapsulate/release traditional water-soluble and poorly water-soluble drugs, proteins, phenolic compounds, or supercritical carbon dioxide (scCO2) for thymol, carvacrol, and eugenol, a promising alternative for traditional antibiotics [2]. Furthermore, we reduced the hydrogel production temperature to ambient conditions and made a simple and cost-effective production process that doesn't require special equipment. The promising results we got pushed us further. So, the current research focuses on the encapsulation/controlled release of antioxidant phenolic compounds extracted from orange peel waste by applying ultrasonic-assisted extraction and deep eutectic solvent(DES) based on glycerol: urea: water. We use a new initiator system based on vitamin C and H2O2to polymerizea methacrylic acid[3]that could be useful for other monomers.As a concluding remark, we achieved significant progress in hydrogels encouragingus to continue further.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202
Синтеза, карактеризација, антиоксидативна и антимикробна активност некиx нових амида естара 1,4-дихидропиридина
No full textThe esters of substituted 1,4-dihydropyirdines (1,4-DHP) are formed in the reaction of an appropriate aldehyde and ethyl acetoacetate in the presence of concentrated water solution of ammonia. The esters form the amides by the reaction with primary amines. The series of the amides has been synthesized with the aim to analyze their chemical characteristics, antioxidant and antimicrobial activity. The amine used in this research is 2-aminothiazole. The antioxidant activity is analysed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) methods and the antimicrobial activity screening was performed by broth microdilution method, using different microbial strains. The characterization of the obtained amides was done by melting points, FTIR, NMR and elemental analysis. The possibilities for further research was suggested, which could lead to the application of selected compounds.Естри супституисаних 1,4-дихидропиридина се формирају у реакцији одговарајућег алдехида и етил-ацетоацетата у присуству амонијум-хидроксида. Наведени естри
прелазе у амиде реакцијом са примарним аминима. Серија оваквих амида је синтетисана са циљем да се испита њихова антиоксидативна и антимиркобна активност, као и
хемијске карактеристике. Амин употребљен за синтезу је 2-аминотиазол. Антиоксидативна активност је анализирана DPPH и ABTS методама, а антимикробна бујон микродилуционом методом. Карактеризација добијених једињења урађена је помоћу тачака
топљења, FTIR, NMR и елементалном анализом. Предложене су могућности за наставак
истраживања, који бу водио њиховој примени одређених испитиваних једињења
Cellulose-Based Waste in a Close Loop as an Adsorbent for Removing Dyes from Textile Industry Wastewater
No full textIn an attempt to reuse fibrous textile waste and, at the same time, to address dye pollution
in textile wastewater, waste cotton-based yarn was utilized as a cheap and sustainable adsorbent, as
well as a row material for carbon adsorbent production. Unmodified yarn and cotton-based carbon
adsorbents were used as adsorbents for dye removal from water. Cotton and cotton/polyester yarn
samples underwent thermal modification through carbonization followed by chemical activation
with KOH. Various techniques, including scanning electron microscopy, Fourier transform infrared
spectroscopy, nitrogen adsorption–desorption isotherms, and surface charge determination, were
employed to analyze the morphological and surface characteristics of the cotton-based adsorbents.
Adsorption properties were evaluated by testing the removal of selected cationic and anionic dyes
from water. The impact of temperature, initial pH and concentration of the dye solution, and
contact time on adsorption were investigated, and experimentally obtained data were analyzed using
theoretical models. While carbonization alone did not significantly enhance adsorption properties,
activated samples exhibited high efficacy in removing both cationic and anionic dyes from water.
Despite the negative influence of the polyester component in the carbon precursor on the efficiency
of activated samples in removing methyl orange, the results indicated that activated cotton and
cotton/polyester yarn could be used to prepare highly efficient adsorbents for the rapid removal of
methylene blue from real wastewater samples
Cell viability assessment and ion release profiles of GICs modified with TiO2- and Mg-doped hydroxyapatite nanoparticles
No full textObjectives: To assess and compare the cell viability and ion release profiles of two conventional glass ionomer cements (GICs), Fuji IX and Ketac Molar EasyMix, modified with TiO2 and Mg-doped-HAp nanoparticles (NPs). Methods: TiO2 NPs, synthesized via a sol–gel method, and Mg-doped hydroxyapatite, synthesized via a hydrothermal process, were incorporated into GICs at a concentration of 5 wt.%. The biocompatibility of prepared materials was assessed by evaluating their effects on the viability of dental pulp stem cells (DPSCs), together with monitoring ion release profiles. Statistical analysis was performed using One-way analysis of variance, with significance level p < 0.05. Results: The addition of NPs did not significantly affect the biocompatibility of GICs, as evidenced by comparable decreased levels in cell viability to their original formulations. Distinct variations in cell viability were observed among Fuji IX and Ketac Molar, including their respective modifications. FUJI IX and its modification with TiO2 exhibited moderate decrease in cell viability, while other groups exhibited severe negative effects. While slight differences in ion release profiles were observed among the groups, significant variations compared to original cements were not achieved. Fluoride release exhibited an initial “burst release” within the initial 24 h in all samples, stabilizing over subsequent days. Conclusions: The addition of NPs did not compromise biocompatibility, nor anticariogenic potential of tested GICs. However, observed differences among FUJI IX and Ketac Molar, including their respective modifications, as well as induced low viability of DPSC by all tested groups, suggest the need for careful consideration of cement composition in their biological assessments. Clinical significance: The findings contribute to understanding the complex interaction between NPs and GIC matrices. However, the results should be interpreted recognizing the inherent limitations associated with in vitro studies. Further research avenues could explore long-term effects, in vivo performance, and potential clinical applications
Evaluation of possible improvements of forced periodically operated reactor in which methanol synthesis takes place – based on the Nonlinear Frequency Response analysis
No full textThe continuous industrial chemical processes are typically designed through steady-state conditions. Nevertheless, there is evidence that processes can be intensified by applying optimized forced periodic operation. Possible improvements in reactor performances caused by the implementation of forced periodic operation (FPO) can be successfully evaluated by applying a nonlinear frequency response (NFR) analysis, before experimental investigation. In this study, we will present the results of two case studies based on heterogeneously catalyzed methanol synthesis in a continuous stirred tank reactor (CSTR). The first is an isothermal case, and the second is a more complicated and more realistic, non-isothermal case.This is a paper for 15th International Conference on Applied Energy (ICAE2023), Dec. 3-7, 2023, Doha, Qatar
Plant-Assisted Synthesis of Ag-Based Nanoparticles on Cotton: Antimicrobial and Cytotoxicity Studies
No full textThe syntheses of Ag-based nanoparticles (NPs) with the assistance of plant extracts have been shown to be environmentally benign and cost-effective alternatives to conventional chemical syntheses. This study discusses the application of Paliurus spina-christi, Juglans regia, Humulus lupulus, and Sambucus nigra leaf extracts for in situ synthesis of Ag-based NPs on cotton fabric modified with citric acid. The presence of NPs with an average size ranging from 57 to 99 nm on the fiber surface was confirmed by FESEM. XPS analysis indicated that metallic (Ag0) and/or ionic silver (Ag2O and AgO) appeared on the surface of the modified cotton. The chemical composition, size, shape, and amounts of synthesized NPs were strongly dependent on the applied plant extract. All fabricated nanocomposites exhibited excellent antifungal activity against yeast Candida albicans. Antibacterial activity was significantly stronger against Gram-positive bacteria Staphylococcus aureus than Gram-negative bacteria Escherichia coli. In addition, 99% of silver was retained on the samples after 24 h of contact with physiological saline solution, implying a high stability of nanoparticles. Cytotoxic activity towards HaCaT and MRC5 cells was only observed for the sample synthetized in the presence of H. lupulus extract. Excellent antimicrobial activity and non-cytotoxicity make the developed composites efficient candidates for medicinal applications
Synthesis of AgCoCuFeNi High Entropy Alloy Nanoparticles by Hydrogen Reduction-Assisted Ultrasonic Spray Pyrolysis
No full textBecause of their high mixing entropies, multi-component alloys can exhibit enhanced catalytic activity compared to traditional catalysts in various chemical reactions, including hydrogenation, oxidation, and reduction processes. In this work, new AgCoCuFeNi high entropy alloy nanoparticles were synthesized by the hydrogen reduction-assisted ultrasonic spray pyrolysis method. The aim was to investigate the effects of processing parameters (reaction temperature, precursor solution concentration, and residence time) on the microstructure, composition, and crystallinity of the high entropy alloy nanoparticles. The characterization was performed with scanning electron microscope, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The syntheses performed at 600, 700, 800, and 900 °C, resulted in smaller and smoother spherical particles with a near-equiatomic elemental composition as the temperature increased to 900 °C. With 0.25, 0.1, and 0.05 M precursor solutions, narrower size distribution and uniform AgCoCuFeNi nanoparticles were produced by reducing the solution concentration to 0.05 M. A near-equiatomic elemental composition was only obtained at 0.25 and 0.05 M. Increasing the residence time from 5.3 to 23.8 s resulted in an unclear particle microstructure. None of the five metal elements were formed in the large tubular reactor. X-ray diffraction revealed that various crystal phase structures were obtained in the synthesized AgCoCuFeNi particles