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Advancing 3D bioprinting for post-mastectomy breast reconstruction: the potential of placenta tissue as a bioink
No full textBreast cancer (BC) is, according to the data from 2020, the cancer with the highest estimated incidence rates among women, and current surgical procedures for breast cancer patients involve mastectomy and breast conserving surgeries. Despite their safety and feasibility for patients, existing breast
reconstruction techniques post mastectomy carry the risk of potential complications, and do not significantly alter the likelihood of disease recurrence compared to mastectomy alone. Hence, these factors must be considered when evaluating the available breast reconstruction options post-mastectomy. The field of tissue engineering has been intensively growing primarily focusing on crafting diverse scaffolds as templates for tissue regeneration. With great progress in this area various materials are on our disposal for possible scaffold fabrication, including natural and synthetic polymers,
and composite materials. The choice of material depends on the specific tissue being engineered, as well as the desired mechanical and biochemical properties. Human amniotic membrane (hAM), the
innermost layer of the placenta has been utilized in skin and cornea regeneration,and numerous studies have demonstrated its antitumor, antifibrotic, anti-inflammatory, and immunomodulatory
properties. In this study, we aim to develop soft tissue-like scaffold biomaterial for 3D bioprinting using human AM homogenate (hAM-h) that will preserve and exhibit its regenerative and antitumor effects over an extended period when applied. By establishing advanced 3D bioprinting techniques for this scaffold fabrication, we will enable more accessible and personalized regenerative medicine practices in breast reconstruction
Effect of tempering parameters on microstructure and hardness of a low alloy armor steel
No full textThe final stage of heat treatment that gives high hardness to armor steels its final structure and
characteristics is tempering after quenching. The precipitation of carbides from the supersaturated solution is
influenced by the tempering regime selected. The steel used in this work was a low alloy quenched and tempered steel
(commercial name “PROTAC”), with following chemical composition: 0.32 wt.% C, 0.44 wt.% Mn, 0.98 wt.% Cr, 3.09
wt.% Ni, 0.43 wt.% Mo, 0.019 wt.% Nb, 0.003 wt.% Ti, 0.035 wt.% V. The samples were tempered at various
temperatures between 200 and 500°C for varying periods of time after being quenched in oil at 925°C. The samples
were examined using hardness testing, scanning electron microscopy, and light microscopy. The highest value of
hardness of 430 HV was obtained after tempering at 300°C for 15 min. Due to the comparatively short tempering
duration, this result was attributed to the precipitation of coherent and semi-coherent ferrous carbide particles rather
than alloying element carbides. After reaching the maximum value of 430 HV hardness drops with further increase of
temperature. The increase of hardness by prolonged tempering time was higher at 300°C than at 200°C
Numerical and metallographic analysis of a welded joint withmicrocrackin the root
No full textThe goal of this research was to determine the behaviour of a welded joint with an incompleterootpenetration defect, which was subjected to tensile loads. After the actual experiments, small crackswereobserved in near the fusion line, on the root side of the weld, with lengths of 0.2 and 0.3 mm, dependingonthe test specimen. Following the previous experience with welded joints that have multiple defects, it wasconcluded that further analysis is required, and for this reason, numerical models based on finiteelementmethod, which would simulate the tensile behaviour of real specimens with previously identifiedcrackswere developed. In addition, there was the question of microstructure in this critical area of the weldedjoint.Metallographic tests were performed in order to determine if there was anything out of the ordinaryinterms of microstructures and their distribution in the heat affected zone and the fusion line. Thiswasdecided based on previous experiments, wherein failure of tensile test specimens made of this material (which was low-alloyed low-carbon steel with commercial designation S275J2) would more oftenthannotoccur in the fusion line. Microstructural investigation, along with the numerical simulations, didnot reveal anything unusual, both due to the nature of the material used and the fact that the observed cracksweretoo short to have a significant effect on the integrity of the welded joint. This approach, however, couldprove quite valuable for materials which are more demanding in terms of welding and heat treatment.Book of Abstract
The expression of terminal monosaccharides on immune complexes IgG glycans in rheumatoid arthritis
No full textRheumatoid arthritis (RA) is characterised by the presence of rheumatoid factors (RFs;autoantibodies against Fc region of IgG molecules) and autoantibodies against citrullinated peptides(ACPAs), mostly of IgG isotype. Both RFs and ACPAs form immune complexes (IC). IgG glycansare important for IgG proinflammatory effects and in this study, we analysed expression of terminalmonosaccharides of circulating immune complexes (CIC) IgG glycans in RA. IgG from polyethyleneglycol (PEG) precipitable CICs of healthy individuals and RA patients, were isolated by Protein Gchromatography. The expression of IgG heavy and light chains’ terminal galactose (Gal), sialicacid, N-acetyl galactosamine (GalNAc), fucose (Fuc), and bisecting GalNAc were performed withreducing SDS-PAGE followed by blotting with RCA I, SNA, GS II, UEA and succ. WGA lectins.We detected a decreased expression of Gal (39%) and increased expression of sialic acid (31%) onCIC IgG heavy chains. Due to difference in IgG light chains glycans expression, in both control andRA, two light chain bands (L1 and L2), slightly different in molecular weight were detected. CICIgG L1 (higher molecular weight) expressed increased level of Gal (35%) and decreased level ofGalNAc expression (21%) on RA, comparing to control. On the IgG L2 light chains, an increasedFuc expression was detected (24%). The difference between RA and control in the expression ofother CIC IgG heavy and light chains’ monosaccharides was not observed. The precise location(variable vs. constant domains) and glycan monosaccharide composition on IgG light and heavychains in RA need further investigation using additional enzymatic and high-performance methods(HPLC/MS)
Estimation of enzyme affinity of chemically bonded Glucose Oxidase onto polyaniline-based enzyme electrode
No full textThe enzyme electrode (EE) was formed by immobilizing Glucose Oxidase by chemical bonding and establishing peptide bonds onto a polyaniline based electrode (PE). The PE was formed electrochemically,using galvanostatic co-polymerization of aniline and m-aminobenzoic acid from an acidic aqueous electrolyte composed of 0.2 mol dm -3 monomers in equal amounts at a constant current density of 2.0 mA cm -2 . The EE response to different concentrations of glucose was evaluated from chronopotentiometric experiments recorded at 10 μA cm -2 , in phosphate buffer at pH 6.8. The dependence of the potentials of EE on glucose concentrations has the shape of a typical rectangular hyperbola, characteristic of Michaelis-Menten enzyme kinetics with the linearity range of the response wider than that of the cross-linked EE. From the Lineweaver-Burk linearization, the estimated value of the apparent Michaelis-Menten constant was 0.50 mmol dm -3 , which is a greater value than for cross-linked enzyme, revealing the slight loss of the activity, as expected for chemical bonding, but still much lower than the value for the free enzyme, indicating high affinity of the chemically bonded enzyme into polyaniline-based electrode material. However, EE obtained by chemical bonding showed much better storage stability compared to the cross-linked EE, which is a good base for analytical applications
Profiling of historical rag papers by their non-cellulosic polysaccharide composition
No full textHemicellulose and pectin are noteworthy components of historical European rag papers, and have not been studied in detail so far. Rag papers were made from used textiles, and fiber-based utilities, such as ropes and bags. These had been prepared until the mid-19th century from plant-based fibers. Their polysaccharide composition could relate to their condition and history. This information can be expected to hold importance for the preservation and conservation of historical objects. We investigated a collection of rag papers of different age for their composition of non-cellulosic polysaccharides, and compared the findings with modern rag papers and wood pulps. Furthermore, a non-destructive determination of the hemicellulose and pectin content by near-infrared spectroscopy was developed. Historical rag papers had a lower hemicellulose/pectin content than pulps; the fractions of rhamnose, galactose, and arabinose were higher, while xylose was lower. In modern rag papers, xylose tended to be at the higher end of the range, which suggests a degradation of hemicelluloses/pectin over time or a change in raw materials and manufacturing. Rag papers also showed higher crystallinity than wood pulp papers. These findings provide insights into rag paper characteristics and offer potential classification methods
The influence of polycaprolactone content on the surface properties of polyurethane networks
No full textThe aim of this work was to examine the influence of polycaprolactone (PCL) as a soft segment (SS) on the surface properties of polyurethane networks (PUNs). Five PUNs with different SS content (from 10 to 50 wt%) were prepared using Boltorn® aliphatic hyperbranched polyester of the second pseudo generation and isophorone diisocyanate as components of hard segments. The structure, hydrophobicity, wettability, and swelling behavior of these PUNs were investigated. Primarily, the obtained results showed that properties of prepared PUNs strongly depend on the content of SS that is, PCL. It has been established that the increase of SS content reduced the degree of hydrogen bonding in PUNs. Also, the increase of the SS content in PUNs induced appearance of more pronounced microphase separated morphology, better hydrophobicity and non-wetting with diiodomethane. Simultaneously, the increase of the SS content led to the decrease of contact angles with formamide, and surface free energy of the prepared PUNs. These PUNs show good surface properties that are required for their potential application such as coatings
Supplementary material for the article: Kosić, V.; Božić, B.; Dojnov, B.; Banković, P.; Jović-Jovičić, N.; Knežević-Jugović, Z.; Milutinović-Nikolić, A. Significantly improved stabilization of glycoside hydrolases important in food industry by immobilization onto appropriately modified beidellite. Applied Clay Science 2024, 250, 107289. https://doi.org/10.1016/j.clay.2024.107289
No full textThree glycoside hydrolases (α-amylase, xylanase and pullulanase) were immobilized on low-cost, environmentally friendly, easily modified clay rich in beidellite. Modifications included common procedures: Na-exchange, acid activation, pillaring, pillaring followed by acid activation, and organo-modifications with chitosan. Supports were characterized by chemical analysis, low temperature N2 physisorption, X-ray powder diffraction (XRPD) and Fourier-transform infrared (FT-IR) spectroscopy. The point of zero charge was also determined. Specific activity of different immobilizates of selected glycoside hydrolases was notably influenced by the type of chemical modification of supports. For each enzyme optimal support was chosen and storage stability was tested. α-Amylase immobilized on acid-activated support retained up to 95% of its initial specific activity of 105.6 ± 5.1 U g−1 after a testing period of 120 days. The most suitable support for xylanase was chitosan-modified beidellite with having specific activity of 90.0 ± 1.4 U g−1 which retained >50% its value after 120 days. Specific activity of pullulanase immobilized on pillared sample that was subsequently activated by acid was 44.5 ± 0.7 U g−1. Initial activity was preserved up to 33% for the same testing period. Comparing these results to the storage stability of the free enzymes that completely lost their activity for the longest period of 40 days, it can be concluded that appropriately modified beidellite- based clays could be used as suitable supports for stabilization of glycoside hydrolases. Nevertheless, further characterization of immobilizates (pH, thermal and operational stability) is needed in order to raise the suitability for larger scale processes in food industry.Related to: [https://technorep.tmf.bg.ac.rs/handle/123456789/7279]Supplementary material for: [https://doi.org/10.1016/j.clay.2024.107289
Višeslojne ugljenične nanocevi kao nosač lipaze za organsku sintezu: pregled najnovijih trendova
No full textLipase-catalyzed organic reactions have been widely practiced in the past three decades. Especially interesting are insoluble/immobilized forms due to providing a possibility of facile use and recyclability, thus reducing process costs, and making the procedure more environmentally friendly. Carbon-based supports have been extensively exploited for this purpose, because of neutral and biodegradable nature and thermal and chemical stability. Their high specific surface area, characteristic surface morphology and lower mass transfer resistances play a vital role in the performance of the attached enzyme. This review paper presents an overview of the main aspects of lipase immobilized on multi-walled carbon nanotubes (MWCNTs). Moreover, different immobilization strategies to achieve a biocatalyst with improved performances are discussed. Furthermore, as lipases are considered to have high commercial worth for synthesis of valuable organic molecules, the second part of the paper is dedicated to the overview of the most important industrial sectors in which these nanobiocatalysts have been used. In specific, applications in biodiesel production, flavour ester synthesis and racemization are summarized.Lipaze su poslednjih decenija široko rasprostanjeni katalizatoriu raznovrsnim organskim reakcijama. Posebno su interesantne u imobilisanom/nerastvornom obliku jer je na ovaj način olakšana njihova upotreba uz mogućnost recikliranja i ponovne upotrebe čime se smanjuju troškovi samog procesa i postupak je ekološki prihvatljiviji. Kao nosači za vezivanje nanomaterijali na bazi ugljenika, posebno ugljenične nanocevi, su našli primenu zbog svojih izuzetnih fizičkih, mehaničkih i hemijskih svojstava. Njihova velika specifična površina, karakteristična površinska morfologija i smanjen otpor prenosu mase igraju vitalnu ulogu u performansama vezanog enzima. Ovaj pregledni rad predstavlja prikaz glavnih aspekata lipaze imobilisane na višeslojne ugljenične nanocevi i različitih strategija imobilizacije za dobijanje biokatalizatora sa poboljšanim svojstvima. Takođe, kako su lipaze enzimi od velikog komercijalnog značaja za organsku sintezu i primenu u biotehnologiji, drugi deo rada posvećen je pregledu najvažnijih industrijskih sektora u kojima su ovi nanobiokatalizatori našli primenu. Shodno tome, dat je pregled proizvodnje biodizela, mirisnih estara i racemizacij
Entropy-weighted water quality index, hydrogeochemistry, and Monte Carlo simulation of source-specific health risks of groundwater in the Morava River plain (Serbia)
No full textPopulation growth, urbanization, industry, floods, and agriculture globally degrade groundwater in river plains, necessitating action for its quality assessment and management. Hence, a comprehensive methodology, including hydrogeochemical facies (Piper, Gibbs), irrigation indices (SAR, Wilcox), entropy-weighted water quality index (EWQI), positive matrix factorization (PMF), and Monte Carlo simulation of source-specific health risks was used in this study to analyze groundwater in the Morava river plain (Serbia). The results revealed a prevalent Ca–Mg–HCO3 groundwater type, influenced by water–rock interactions. Although groundwater was found suitable for irrigation, only 66.7 % of the samples were considered drinkable. Agricultural activities, natural processes, and municipal wastewater were identified as primary pollution sources. The incremental lifetime cancer risk (ILCR) and hazard index (HI) threshold exceedance for adults and children ranged from 8.5 % to 39 % of the samples, with arsenic identified as the most risk-contributing contaminant. These findings provide valuable insights for researchers studying groundwater vulnerability in river plains