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[en] In this article authors made conclusion that at influence ofmonochromatic irradiation the structure transformations of cellulose pass onexcitation mechanism of freedom oscillation levels and don't determine byheat action of this irradiation
[en] When cultured under static conditions, bacterial cellulose pellicles, by the nature of the polymer synthesis that involves molecular oxygen, are characterized by two distinct surface sides. The upper surface is denser in fibers (entangled) than the lower surface that shows greater surface porosity. Human umbilical vein endothelial cells (HUVECs) were used to exploit how the microarchitecture (i.e., surface porosity, fiber network structure, surface topology, and fiber density) of bacterial cellulose pellicle surfaces influence cell–biomaterial interaction and therefore cell behavior. Adhesion, cell ingrowth, proliferation, viability and cell death mechanisms were evaluated on the two pellicle surface sides. Cell behavior, including secondary necrosis, is influenced only by the microarchitecture of the surface, since the biomaterial is extremely pure (constituted of cellulose and water only). Cell–cellulose fiber interaction is the determinant signal in the cell–biomaterial responses, isolated from other frequently present interferences such as protein and other chemical traces usually present in cell culture matrices. Our results suggest that microarchitecture of hydrogel materials might determine the performance of biomedical products, such as bacterial cellulose tissue engineering constructs (BCTECs). - Highlights: • Topography of BC pellicle is relevant to determine endothelial cells' fate. • Cell–biomaterial response is affected by the topography of BC-pellicle surface. • Endothelial cells exhibit different behavior depending on the BC topography. • Apoptosis and necrosis of endothelial cells were affected by the BC topography
[en] Complete text of publication follows. Cultural heritage conservation is very important for a community, not only for protecting economically valuable physical assets, but also for preserving its practices, history, and a sense of continuity and identity. One of the reasons of decaying of cultural heritage and particularly of archives is the harmful activity of microorganisms. Their activity affects not only the material of books and documents, but also the working personnel, by inducing occupational diseases. One of the methods used to prevent these negative effects is the use of ionizing radiation, in order to decrease the microbial contamination. This work presents microbiological results obtained during the development of irradiation treatments for archive materials: initial contamination of paper items, environment control and radiation resistance of microorganisms isolated from the paper items. The irradiation dose should be effective but as low as possible because it is known that a high dose of radiation could induce damage by modification of the cellulose and its degree of polymerization, making it more fragile and brown-colored. The use of a statistical method derived from VDmax Method (ISO 11137-2) is proposed for the substantiation of the decontamination dose for archives.
[en] Process modeling of conveyer dryer for cellulosic fibre drying demands many fundamental insights. Present study highlights detailed cellulosic fibre drying Aspects like mass transfer correlation relating mass transfer rate with process conditions, normalized drying curve and critical moisture content. Cellulosic fibre drying follows falling rate period, where rate of mass transfer decreases with moisture content. Conveyer dryer process model for commercial cellulosic fibre drying was developed and validated successfully. Moderate drying strategy derived based on developed process model and drying fundamentals was deployed at commercial scale which helped in reducing the moisture variability. (Author)
[en] A micro/nano pattern was simply fabricated on the surface of a hydroxyethyl cellulose (HEC) thin film and its properties were investigated. HEC is easily dissolved in water and has excellent properties such as viscosity, transparency and stability. In this study, HEC was prepared by chemical processing with water-insoluble cellulose and water-soluble ether and was then cast as a flexible film. With the use of a micro patterned metal mold, the pattern was simply replicated on the solid-state HEC film. Micro/nano hybrid structured patterns consisting of micro-scale structures of about 10 μm and nano-scale fibrils of less than 10 nm were prepared, and the surface characteristics of the patterned HEC film were experimentally verified. Measurements showed that the micro/nano hybrid structure resulted in a higher water drop contact angle, but the contact angle decreased gradually with increasing wetting time.
[en] Ablation thresholds of historical paper are determined with the aid of direct measurements of the amount of ablated particles. Curves of the amount of ablated particles versus laser fluence clearly show two ablation thresholds. Such an ablation scenario can be due to the presence of impurities in and porosity of paper. Paper surface is not damaged when the fluence increases from the first to second threshold but material removal is detected. Ablated particles are collected and can be analyzed using, for example, Raman microspectroscopy. When the fluence exceeds the second threshold, paper is damaged and cellulose fibers are ruptured. (letter)
[en] This research mainly focuses on developing a natural cellulose nano fibre (CNF) from kenaf bast fibre and its potential for enzyme immobilization support. CNF was isolated by using a combination between chemical and mechanical treatments such as alkaline process and high-intensity ultrasonication process to increase the efficiency of hemicelluloses and lignin removal, and to reduce its size into nano-order. The morphological study was carried out by using scanning electron microscope (SEM), indicating most of CNF diameter in range of 50-90 nm was obtained. The result of chemical analysis shows that cellulose content of raw bast fibre, bleached pulp fibre and CNF are 66.4 %, 83.7 % and 90.0 %, respectively. By decreasing the size of cellulose fibre, it increases the number of (O-H) group on the surface that plays as important role in enzyme immobilization. Covalent immobilization of cyclodextrin glucanotransferase (CGTase) onto CNF support resulted in about 95.0 % of protein loading with 69.48 % of enzyme activity, indicating high immobilization yield of enzyme. The enzymatic reaction of immobilized CGTase was able to produce more than 40 % yield of α-CD. Reusability profile of immobilized CGTase resulted in more than 60 % of retained activity up to 7 cycles. Therefore, the CNF is highly potential to be applied as enzyme immobilization support. (author)
[en] Cellulose nanofibers (CNF) is used in various pharmaceutical applications due to its unique characteristics i.e., biodegradability, mechanical and biological properties. CNF is often produced by spray drying process, knowledge of the drying kinetics in terms of mass and heat transfer on the scale of single droplet is important for process development and model validation. Acoustic levitator was used to study drying process of CNF suspension at different air temperatures and initial CNF concentrations. The unique property of acoustic levitation to hold single droplet contactless in the air, enables to study particle morphology during drying process, calculate evaporation rate and estimate particle porosity. Results show that packed particles result at lower initial concentration and temperature has a moderate influence on mean porosity of CNF dried particles. (Author)