Publications by authors named "Uros Novak"

Cellulose nanofibrils are one of the keystone materials for sustainable future, yet their poor water repellency hinders their push into industrial applications. Due to complexity and poor economical outcome and/or processing toxicity of the existing hydrophobization methods, nanocellulose loses against its antagonist plastic in medical and food industries. Herein, we demonstrate for the first time the "one-side selective water-repellency activation" in nanocellulose membranes by the means of mild N-plasma treatment, exhibiting lowest wettability after 20 s of treatment.

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Article Synopsis
  • * After 30 cavitation passes, the sludge showed significantly poorer dewaterability and a two-fold increase in Capillary Suction Time (CST), while particle sizes were reduced and surface tension slightly increased.
  • * The cavitated sludge exhibited distinct viscosity behavior compared to untreated sludge, but HC did not enhance methane yield; some correlations between physical properties and viscosity at low shear stress were noted, indicating potential for further research. *
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The article discusses the production of platform chemicals from various biological sources, including glycerol, lignin, cellulose, bio-oils, and sea products. It presents the results of catalytic and downstream processes involved in the conversion of these biomass-derived feedstocks. The experimental approaches are complemented by numerical descriptions, ranging from density functional theory (DFT) calculations to kinetic modellingof the experimental data.

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Biocomposite films from renewable sources are seen to be viable candidates as sustainable, zero-waste packaging materials. In this study, biocomposites films using chitosan and alginate as matrices, and pristine or acetylated cellulose nanocrystals (CNCs) as reinforcement agents, were fabricated, thoroughly characterized in terms of structure (with ATR-FTIR and XRD), morphology (SEM), thermal stability (TGA coupled with FTIR), water content and solubility and mechanical properties and subjected to controlled biological degradation in aqueous environment with added activated sludge. Biodegradation activity was followed through respirometry by measurement of change in partial O pressure using OxiTop® system.

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The development of sensitive, selective, and reliable gaseous hydrogen peroxide (HO) sensors operating at room temperature still represents a remaining challenge. In this work, we have investigated and combined the advantageous properties of a two-dimensional TiCT MXene material that exhibits a large specific surface area and high surface activity, with favorable conducting and stabilizing properties of chitosan. The MXene-chitosan membrane was deposited on the ferrocyanide-modified screen-printed working carbon electrode, followed by applying poly(acrylic acid) as an electrolyte and accumulation medium for gaseous HO.

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Cellulose nanocrystals (CNCs) were acetylated to the various parametrised degrees of substitution (DS), determined through attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and incorporated into alginate (ALG) and chitosan (CH) film-forming solutions. An investigation of morphology with scanning electron microscopy (SEM) revealed increased chemical compatibility with the CH matrix after acetylation, producing a smooth surface layer, while ALG mixed better with pristine CNCs. The ATR-FTIR analysis of films demonstrated inter-diffusional structural changes upon the integration of pristine/modified CNCs.

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A 70% ethanol extract of the rhizome bark of the invasive alien plant species Japanese knotweed (JKRB) with potent (in the range of vitamin C) and stable antioxidant activity was incorporated in 1% into a chitosan biofoil, which was then characterized on a lab-scale. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay confirmed the antioxidant activity of the JKRB biofoil upon contact with the food simulants A, B, C, and D1 (measured half-maximal inhibitory concentrations-IC) and supported the Folin-Ciocalteu assay result. The migration of the antioxidant marker, (-)-epicatechin, into all food simulants (A, B, C, D1, D2, and E) was quantified using liquid chromatography hyphenated to mass spectrometry (LC-MS).

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The aim of the study was to characterize and compare films made of cellulose nanocrystals (CNC), nano-fibrils (CNF), and bacterial nanocellulose (BNC) in combination with chitosan and alginate in terms of applicability for potential food packaging applications. In total, 25 different formulations were made and evaluated, and seven biopolymer films with the best mechanical performance (tensile strength, strain)-alginate, alginate with 5% CNC, chitosan, chitosan with 3% CNC, BNC with and without glycerol, and CNF with glycerol-were selected and investigated regarding morphology (SEM), density, contact angle, surface energy, water absorption, and oxygen and water barrier properties. Studies revealed that polysaccharide-based films with added CNC are the most suitable for packaging purposes, and better dispersing of nanocellulose in chitosan than in alginate was observed.

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Chitin is the most abundant marine biopolymer, being recovered during the shell biorefining of crustacean shell waste. In its native form, chitin displays a poor reactivity and solubility in most solvents due to its extensive hydrogen bonding. This can be overcome by deacetylation.

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Nanoscale-interfaced cellulose nanomaterials are extracted from polysaccharides, which are widely available in nature, biocompatible and biodegradable. Moreover, the latter have a potential to be recycled, upcycled, and formulate therefore a great theoretical predisposition to be used in a number of applications. Nanocrystals, nano-fibrils and nanofibers possess reactive functional groups that enable hydrophobic surface modifications.

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In this work, the kinetic model based on the previously developed metabolic and glycan reaction networks of the ovarian cells of the Chinese hamster ovary (CHO) cell line was improved by the inclusion of transcriptomic data that took into account the values of the RPKM gene (Reads per Kilobase of Exon per Million Reads Mapped). The transcriptomic (RNASeq) data were obtained together with metabolic and glycan data from the literature, and the concentrations with RPKM values were collected at several points in time from two fed-batch processes. First, the fluxes were determined by regression analysis of the metabolic data, then these fluxes were corrected by using the fold change in gene expression as a measure of enzyme concentrations.

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Active chitosan-based films, blended with fibrous chestnut ( Mill.) tannin-rich extract were used to pack Gouda cheese that has been contaminated with spoilage microflora , , and fungi . A comprehensive experimental plan including active chitosan-based films with (i) chestnut extract (CE), (ii) tannic acid (TA), and (iii) without additives was applied to evaluate the film's effect on induced microbiological spoilage reduction and chemical indices of commercial Gouda cheese during 37 days while stored at 4 °C and 25 °C, respectively.

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Experimental and modeling work, described in this article, is focused on the metabolic pathway of Chinese hamster ovary (CHO) cells, which are the preferred expression system for monoclonal antibody protein production. CHO cells are one of the primary hosts for monoclonal antibodies production, which have extensive applications in multiple fields like biochemistry, biology and medicine. Here, an approach to explain cellular metabolism with in silico modeling of a microkinetic reaction network is presented and validated with unique experimental results.

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Conventional isolation of chitin from crustacean waste demands the use of high amounts of hazardous chemicals, hence not leading to a sustainable process. Atmospheric-pressure dielectric barrier discharge (DBD) plasma has demonstrated an enhanced ability to remove proteins directly from the biomass without the formation of any waste. Simultaneously, organic acids have proven very efficient in the removal of inorganic minerals from crustacean waste.

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An active chitosan-based film, blended with the hydrolysable tannin-rich extract obtained from fibrous chestnut wood (Castanea sativa Mill.), underwent a simultaneous engineering optimization in terms of measured moisture content (MC), tensile strength (TS), elongation at break (EB), and total phenolic content (TPC). The optimal product formulation for a homogeneous film-forming solution was sought by designing an empirical Box-Behnken model simulation, based on three independent variables: the concentrations of chitosan (1.

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Background: 2,5-Furandicarboxylic acid (FDCA) is one of the top biomass-derived value-added chemicals. It can be produced from fructose and other C6 sugars via formation of 5-hydroxymethilfurfural (HMF) intermediate. Most of the chemical methods for FDCA production require harsh conditions, thus as an environmentally friendly alternative, an enzymatic conversion process can be applied.

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Chitin displays a highly rigid structure due to the vast intra- and intermolecular hydrogen bonding, thus hindering its dissolution and deacetylation using most solvents. Deep eutectic solvents (DESs) are special and environmentally friendly solvents composed of a hydrogen bond acceptor and a hydrogen bond donor. This allows them to dissolve chitin by disturbing its natural hydrogen bonding while establishing new bonds, hence turning the polymer more susceptible to solvents.

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Chitosan-based films with incorporated supercritical CO hop extract (HE) were developed and evaluated regarding structural, physicochemical, and antibacterial properties. The morphological and spectroscopic analyses have confirmed successful incorporation of HE into the polymer matrix, which affected films' structure and visual appearance. The presence of HE has caused a reduction in the hydrophilic character of films, but also provided a complete UV light blockage at wavelengths below 350 nm.

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Chinese hamster ovary (CHO) epithelial cells are one of the most used therapeutic medical lines for the production of different biopharmaceutical drugs. They have a high consumption rate with a fast duplication cycle that makes them an ideal biological clone. The higher accumulated amounts of toxic intracellular intermediates may lead to lower organism viability, protein productivity and manufactured biosimilar, so a careful optimal balance of medium, bioreactor operational parameters and bioprocess is needed.

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Droplet-based liquid-liquid extraction in a microchannel was studied, both theoretically and experimentally. A full 3D mathematical model, incorporating convection and diffusion in all spatial directions along with the velocity profile, was developed to depict the governing transport characteristics of droplet-based microfluidics. The finite elements method, as the most common macroscale simulation technique, was used to solve the set of differential equations regarding conservation of moment, mass and solute concentration in a two-domain system coupled by interfacial surface of droplet-based flow pattern.

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