Iskanje po katalogu digitalne knjižnice

Opis: : There has been growing interest and increasing attention in the field of functional clothing textiles, particularly in product and process development, as well as innovations in heat-generating, retaining, and releasing fibers to maintain a healthy body temperature without relying on unsustainable energy sources. This study, for the first time, reports the various physio-mechanical properties of surface-functionalized regenerated cellulose fibers (RCFs) coated with ceramic particles. The coating imparts photothermal conversion-based heat generation and retention properties with the aid of polyelectrolyte binders. In this design, ZrC enables the conversion of light energy into thermal energy, providing heat for the human body. A feasible coating process was employed, utilizing industrially feasible exhaustion methods to deposit the ZrC particles onto the RCF surface in conjunction with two distinctive polymeric binders, specifically polyethyleneimine (PEI) and polydiallyldimethylammonium chloride (polyDADMAC). The morphological characteristics and tensile properties of the coated RCFs were analyzed via scanning electron microscopy (SEM) and single-fiber tensile testing. Heat retention and release behaviors of a bundle of fiber samples were assessed using infrared (IR) imaging and an IR emission lamp setup. The SEM results confirmed the successful coating of the ZrC particles on the surface of the RCF samples, influencing negligible on their physical–mechanical properties. The heat retention of the coated RCFs with ZrC and both binders was higher than that of reference regenerated cellulose fibers (RCFs), demonstrating their effective heat generation, retention, and heat release properties. Based on the highlighted prominent results for the coated RCFs, these findings highlight the suitability of the developed functional clothing textiles for targeted applications in non-extreme thermal conditions, ensuring thermo-physiological comfort by maintaining body temperature within a tolerable thermal range (36.5–37.5 ◦C), in contrast to studies reporting significantly higher temperatures (50–78 ◦C) for extreme thermal conditions.
Ključne besede: regenerated cellulose fibers, RCFs, ceramic particles, zirconium carbide, ZrC, surface functionalization, heat generation and retention
Objavljeno v DKUM: 01.04.2025; Ogledov: 0; Prenosov: 92
Celotno besedilo (9,11 MB)
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Opis: Bio-based membranes are becoming highly-desired low-cost, environmentally friendly, and readily available supports for the separation and purification of biomacromolecules. In this work, weak cation-exchange and highly (> 95%) microporous (> 80 μm) cellulose-based membranes were prepared from different weight ratios of carboxymethyl cellulose (CMC) as anionic polymer and cellulose nanofibrils (CNFs) as a stabilizing and structural filler, by the freeze-casting process and citric-acid (CA) mediated in situ cross-linking (esterification). It was ascertained that mono-esterified/grafted CA also contributes to the total carboxylic groups (1.7–2.6 mmol/g), while the CMC-induced CNF orientation affected the membrane’s morphology and lysozyme (Lys) binding capacity. A static binding capacity (SBC) between 370 and 1080 mg/g, and equilibrium within 3.3 h for 1 g/mL Lys was thus achieved with increasing the total solid and CMC content by forming more isotropic microporous structures. The selected membranes were then packed in a chromatographic housing, analyzed for pressure drop, and evaluated for dynamic binding capacity (DBC), depending on the process performance (flow rates, Lys concentration). A DBC in the 165–417 mg/g range was determined at a throughput of 0.5 mL/min, and elution yield of 78–99% with > 95% recovery. The Lys adsorption and transfer were reduced by the increasing flow rate and membrane density due to compressibility issues, resulting in smaller and irregularly distributed pores and the unavailability of carboxylic groups. Although the DBC was still comparable with the commercial CIM® monoliths, the convection-based transport of molecules inside the membrane and the membrane stiffness needs to be improved in further research.
Ključne besede: cation-exchange membrane, cellulose nanofibrils, carboxymethyl cellulose, citric acid, lysozyme, static and dynamic binding capacity
Objavljeno v DKUM: 17.03.2025; Ogledov: 0; Prenosov: 5
Celotno besedilo (3,04 MB)
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Ključne besede: starch aerogels, cellulose, supercritical impregnation, xanthohumol, usnic acid
Objavljeno v DKUM: 15.01.2025; Ogledov: 0; Prenosov: 4
Celotno besedilo (11,15 MB)

Opis: Acetic acid bacteria (AAB) produce acetic acid but are also gaining importance as safe microorganisms for producing extracellular polysaccharides (EPSs). The best-known homopolysaccharides among them are cellulose and levan. In addition, acetic acid bacteria also produce heteropolysaccharides, water-soluble acetans. Isolates from the broth of organic and conventional apple cider vinegar production were screened for biofilm production. Phenotypic and genomic diversity of EPS-producing isolates was assessed. The diversity of phenotypically different EPSs of apple cider vinegar isolates was investigated at the gene level for the following novel strains: Komagataeibacter (K.) melomenusus SI3083, K. oboediens SI3053, K. pomaceti SI3133, and Gluconacetobacter (Ga.) entanii SI2084. Strain K. melomenusus SI3083 possesses cellulose operons bcs1, bcs2, and bcs4 together with the type I acetan cluster in the absence of the levan operon, strain K. oboediens SI3053 has the operons bcs1, bcs2, bcs3, and bcs4, the levan operon, and the acetan cluster (type I), and the strains K. pomaceti SI3133 and Ga. entanii SI2084 both contain recently described novel ace-type II cluster in addition to the incomplete operon bcs1. A comparison of the genetic diversity of these EPSs to those of the reference strains suggests that the studied EPSs are not species-descriptive. The results of this study deepen our understanding of the genetic variability of the EPS genes in AAB, thereby enabling us to better characterize and exploit the various insoluble and soluble exopolysaccharides produced by AAB for biotechnological applications in the future.
Ključne besede: acetic acid bacteria genomes, apple cider vinegar microbiota, biofilm production, bacterial cellulose, acetan, Acetobacter, Komagataeibacter
Objavljeno v DKUM: 26.09.2024; Ogledov: 0; Prenosov: 16
Celotno besedilo (2,45 MB)
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Opis: The microbial production of cellulose using different bacterial species has been extensively examined for various industrial applications. However, the cost-effectiveness of all these biotechnological processes is strongly related to the culture medium for bacterial cellulose (BC) production. Herein, we examined a simple and modified procedure for preparing grape pomace (GP) hydrolysate, without enzymatic treatment, as a sole growth medium for BC production by acetic acid bacteria (AAB). The central composite design (CCD) was used to optimise the GP hydrolysate preparation toward the highest reducing sugar contents (10.4 g/L) and minimal phenolic contents (4.8 g/L). The experimental screening of 4 differently prepared hydrolysates and 20 AAB strains identified the recently described species Komagataeibacter melomenusus AV436T as the most efficient BC producer (up to 1.24 g/ L dry BC membrane), followed by Komagataeibacter xylinus LMG 1518 (up to 0.98 g/L dry BC membrane). The membranes were synthesized in only 4 days of bacteria culturing, 1 st day with shaking, followed by 3 days of static incubation. The produced BC membranes in GP-hydrolysates showed, in comparison to the membranes made in a complex RAE medium 34 % reduction of crystallinity index with the presence of diverse cellulose allomorphs, presence of GP-related components within the BC network responsible for the increase of hydrophobicity, the reduction of thermal stability and 48.75 %, 13.6 % and 43 % lower tensile strength, tensile modulus, and elongation, respectively. Here presented study is the first report on utilising a GP-hydrolysate without enzymatic treatment as a sole culture medium for efficient BC production by AAB, with recently described species Komagataeibacter melomenusus AV436T as the most efficient producer in this type of food-waste material. The scale-up protocol of the scheme presented here will be needed for the cost-optimisation of BC production at the industrial levels.
Ključne besede: grape pomace hydrolysate, bacterial cellulose, acetic acid bacteria, Komagataeibacter melomenusus
Objavljeno v DKUM: 26.07.2024; Ogledov: 98; Prenosov: 13
Celotno besedilo (8,06 MB)
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