Search

The aim of this study was to analyse the steam gasification process of ‘Janina’ coal with and without Na-, K- and Ca-catalysts. The catalysts were physically mixed with the coal due to the simplicity of this method, short time of execution and certainty that the amount of catalyst is exactly as the adopted one. The isothermal measurements were performed at 800, 900 and 950°C and a pressure of 1 MPa using thermovolumetric method. The obtained results enabled assessment of the effect of analysed catalysts on the process at various temperatures by determination of: i) carbon conversion degree; ii) yield and composition of the resulting gas; and iii) kinetics of formation reactions of main gas components – CO and H2. The addition of catalysts, as well as an increase in operating temperature, had a positive effect on the coal gasification process – reactions rates increased, and the process time was reduced.

The thermogravimetric method allows to carry out measurements both in isothermal conditions for a given temperature and in non-isothermal conditions at a set heating rate. The aim of the work was to compare the process of gasification of the same coal in an atmosphere of CO2 under isothermal and non-isothermal conditions. The measurements were carried out with the use of DynTHERM Thermogravimetric analyzer by Rubotherm. Char derived from Polish bituminous coal “Janina” was used as material for gasification. In case of the isothermal method the measurements were performed at three temperatures – 850 °C, 900 °C and 950 °C, while in case of the non-isothermal method for three heating rates, i.e. 3 K/min, 5 K/min and 10 K/min. Based on the results obtained, kinetics curves of conversion degree of the gasification process were developed and kinetic parameters of the gasification reaction i.e. reaction order, activation energy and pre-exponential factor were determined. The values of the kinetic parameters obtained from measurements performed in isothermal and non-isothermal conditions were compared.

It has been shown that the nature of the metal precursor and the thermal effects during calcination determine the physicochemical properties of the catalysts and their catalytic activity in the levulinic acid (LA) and 5-hydroxymethylfurfural (HMF) hydrogenation reactions. The endothermic effect during calcination of the inorganic nickel precursor promoted higher metal dispersion and stronger interaction with the alumina surface. In contrast, the exothermic effects during the calcination of organic nickel precursors resulted in smaller metal dispersion and lower interaction with the support surface. A clear relationship was found between the size of the metal crystallites and the yield of LA hydrogenation reaction. The smaller crystallites were more active in the LA hydrogenation reaction. In turn, the size of the metal particles and their nature of interaction with the surface of the alumina influence the hydrogenation pathways of the HMF.

Alkaline earth metal oxide (MgO, CaO, SrO) catalysts supported on BEA zeolite were prepared by a wet impregnation method and tested in the transesterification reaction of rapeseed oil with methanol towards the formation of biodiesel (FAMEs-fatty acid methyl esters). To assess the influence of the SiO 2 /Al 2 O 3 ratio on the catalytic activity in the tested reaction, a BEA zeolite carrier material with different Si/Al ratios was used. The prepared catalysts were tested in the transesterification reaction at temperatures of 180 °C and 220 °C using a molar ratio of methanol/oil reagents of 9:1. The transesterification process was carried out for 2 h with the catalyst mass of 0.5 g. The oil conversion value and efficiency towards FAME formation were determined using the HPLC technique. The physicochemical properties of the catalysts were determined using the following research techniques: CO 2 -TPD, XRD, BET, FTIR, and SEM-EDS. The results of the catalytic activity showed that higher activity in the tested process was confirmed for the catalysts supported on the BEA zeolite characterized by the highest silica/alumina ratio for the reaction carried out at a temperature of 220 °C. The most active zeolite catalyst was the 10% CaO/BEA system (Si/Al = 300), which showed the highest triglyceride (TG) conversion of 90.5% and the second highest FAME yield of 94.6% in the transesterification reaction carried out at 220 °C. The high activity of this system is associated with its alkalinity, high value of the specific surface area, the size of the active phase crystallites, and its characteristic sorption properties in relation to methanol.

Application of municipal solid and wood waste, as dominant sources of biomass, could be a promising alternative for producing energy from renewables via thermochemical gasification technology. In this paper, a study of thermogravimetric analysis (TGA) and excurrent gas composition produced by the municipal solid waste (MSW) and wood biomass gasification is presented. Thermogravimetric and heat flow curves for waste samples were performed at the temperature interval of 20-890 °C with a heating rate of 10 °C min -1 under a nitrogen atmosphere. According to thermal analysis data, differential scanning calorimetry (DSC) curves, the degradation stages of waste samples was determined, which correspond to the mono- or bimodal evolution of volatile compounds and the degradation of the resulting carbon residue. The gasification experiments were conducted in a high-pressure quartz reactor at temperatures of 850, 900, and 950 °C, using steam (0.3 g/min) and argon (2 dm 3 /min) as the gasifying agents. To ascertain the syngas composition, gas chromatography was employed in conjunction with a thermal conductivity detector. Both types of biomass showed remarkably similar syngas compositions. The highest concentration of hydrogen-rich gases was recorded at 950 °C for wood biomass, with 42.9 vol% and 25.2 vol% for hydrogen (H 2 ) and carbon monoxide (CO), and for MSW, with an average 44.2 vol% and 18 vol% for H 2 and CO. Higher temperatures improved the syngas composition by promoting endothermic gasification reactions, increasing hydrogen yield while decreasing tar and solid yields. This research helped to comprehend the evolution of the gasification process and the relationship between increased H 2 and CO production as the gasification temperature increased., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Some forms of bovine lactoferrin (bLf) are effective in delaying Clostridioides difficile growth and preventing toxin production. However, therapeutic use of bLf may be limited by protein stability issues. The objective of this study was to prepare and evaluate colon-targeted, pH-triggered alginate microparticles loaded with bioactive bLf and to evaluate their anti-C difficile defense properties in vitro. Different forms of metal-bound bLf were encapsulated in alginate microparticles using an emulsification or internal gelation method. The microparticles were coated with chitosan to control protein release. In vitro drug release studies were conducted in pH-simulated gastrointestinal conditions to investigate the release kinetics of encapsulated protein. No significant release of metal-bound bLf was observed at acidic pH; however, on reaching simulated colonic pH, most of the encapsulated lactoferrin was released. The application of bLf (5 mg/mL) delivered from alginate microparticles to human intestinal epithelial cells significantly reduced the cytotoxic effects of toxins A and B as well as bacterial supernatant on Caco-2 and Vero cells, respectively. These results are the first to suggest that alginate-bLf microparticles show protective effects against C difficile toxin-mediated epithelial damage and impairment of barrier function in human intestinal epithelial cells. The future potential of lactoferrin-loaded alginate microparticles against C difficile deserves further study., (Copyright © 2019 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.)

Herein we report on a drastic release of metal ions from the Fe-bound transferrin, and Fe- or Mn-bound lactoferrin, observed upon the increase in the separation voltage during CE-based analysis. To verify whether this process is caused directly by electric field, we developed an Isothermal Voltage Increase approach (IVI), which is the extension of methods reported by Krylov et al. IVI ensures isothermal conditions while increasing separation voltage by a hydrodynamic pushing of the injected sample to the actively cooled capillary section, combined with a rationale choice of cooling temperature, dependent on the value of current. Interestingly, the application of IVI revealed that the previously observed effect was caused solely by the insufficient dissipation of Joule heating - the saturation of each protein remained unchanged despite a significant rise in the electric field. This outcome demonstrates how crucial is to ensure an effective temperature control for preventing systematic errors in the analysis of biomolecular complexes. IVI seems also to be a simple and useful tool for discovering new potential processes that may be stimulated directly by electric field., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Translocation of bacteria, primarily Gram-negative pathogenic flora, from the intestinal lumen into the circulatory system leads to sepsis. In newborns, and especially very low birth weight infants, sepsis is a major cause of morbidity and mortality. The results of recently conducted clinical trials suggest that lactoferrin, an iron-binding protein that is abundant in mammalian colostrum and milk, may be an effective agent in preventing sepsis in newborns. However, despite numerous basic studies on lactoferrin, very little is known about how metal saturation of this protein affects a host's health. Therefore, the main objective of this study was to elucidate how iron-depleted, iron-saturated, and manganese-saturated forms of lactoferrin regulate intestinal barrier function via interactions with epithelial cells and macrophages. For these studies, a human intestinal epithelial cell line, Caco-2, was used. In this model, none of the tested lactoferrin forms induced higher levels of apoptosis or necrosis. There was also no change in the production of tight junction proteins regardless of lactoferrin metal saturation status. None of the tested forms induced a pro-inflammatory response in Caco-2 cells or in macrophages either. However, the various lactoferrin forms did effectively inhibit the pro-inflammatory response in macrophages that were activated with lipopolysaccharide with the most potent effect observed for apolactoferrin. Lactoferrin that was not bound to its cognate receptor was able to bind and neutralize lipopolysaccharide. Lactoferrin was also able to neutralize microbial-derived antigens, thereby potentially reducing their pro-inflammatory effect. Therefore, we hypothesize that lactoferrin supplementation is a relevant strategy for preventing sepsis., Competing Interests: The authors declare that they have no conflict of interest.

The previously published method allowing the separation of non-ferric (iron-free) and ferric (iron-saturated) forms of human serum transferrin via capillary electrophoresis has been further developed. Using a surface response methodology and a three-factorial Doehlert design we have established a new optimized running buffer composition: 50mM Tris-HCl, pH 8.5, 22.5% (v/v) methanol, 17.5mM SDS. As a result, two previously unobserved monoferric forms of protein have been separated and identified, moreover, the loss of ferric ions from transferrin during electrophoretic separation has been considerably reduced by methanol, and the method selectivity has been yet increased resulting in a total separation of proteins exerting only subtle or none difference in mass-to-charge ratio. The new method has allowed us to monitor the gradual iron saturation of transferrin by mixing the iron-free form of protein with the buffers with different concentrations of ferric ions. It revealed continuously changing contribution of monoferric forms, characterized by different affinities of two existing iron binding sites on N- and C-lobes of protein, respectively. Afterwards, the similar experiment has been conducted on-line, i.e. inside the capillary, comparing the effectiveness of two possible modes of the reactant zones mixing: diffusion mediated and electrophoretically mediated ones. Finally, the total time of separation has been decreased down to 4min, taking the advantage from a short-end injection strategy and maintaining excellent selectivity., (Copyright © 2014 Elsevier B.V. All rights reserved.)

A capillary electrophoresis-based method for the cost-effective and high efficient separation of iron-free and iron-saturated forms of two members of transferrin family: transferrin and lactoferrin has been developed. The proposed qualitative method relying on the SDS application allowed us to separate iron-free and iron-saturated forms of these proteins, as well as human serum albumin, used as an internal standard. Owing to the distinct migration times under established conditions, the combination of transferrin and lactoferrin assays within a single analytical procedure was feasible. The performance of the method using a fused-silica capillary has been compared with the results obtained using the same method but performed with the use of a neutral capillary of the same dimensions. Neutral capillary has been used as an alternative, since the comparable resolution has been achieved with a concomitant reduction of the electroosmotic flow. Despite of this fact, the migration of analytes occurred with similar velocity but in opposite order, due to the reverse polarity application. A quantitative method employing fused-silica capillary for iron saturation study has been also developed, to evaluate the iron saturation in commercial preparations of lactoferrin., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Lactoferrin is considered as a part of the innate immune system that plays a crucial role in preventing bacterial growth, mostly via an iron sequestration mechanism. Recent data show that bovine lactoferrin prevents late-onset sepsis in preterm very low birth weight neonates by serving as an iron chelator for some bacterial strains; thus, it is very important to control the iron saturation level during diet supplementation. An accurate estimation of lactoferrin iron saturation is essential not only because of its clinical applications but also for a wide range of biochemical experiments. A comprehensive method for the quantification of iron saturation in lactoferrin preparations was developed to obtain a calibration curve enabling the determination of iron saturation levels relying exclusively on the defined ratio of absorbances at 280 and 466 nm (A(280/466)). To achieve this goal, selected techniques such as spectrophotometry, ELISA, and ICP-MS were combined. The ability to obtain samples of lactoferrin with determination of its iron content in a simple and fast way has been proven to be very useful. Furthermore, a similar approach could easily be implemented to facilitate the determination of iron saturation level for other metalloproteins in which metal binding results in the appearance of a distinct band in the visible part of the spectrum.