Cellulose Fibres Funcionalised by Chitosan: Characterization and Application

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Antimicrobial efficiency of functionalized cellulose fibres as potential medical textiles

This chapter presents an overview of methods for cellulose fibres functionalization in order to introduce antimicrobial activity. In view the need for ecologically friendly textiles antimicrobial finishing is introduced, together with some strategies for the functionalization of fibres using biodegradable polysaccharides such as the use of chitosan. Additionally,the methods used for the microbiological testing of these fibres are discussed and the current disadvantages of these methods indicated. Moreover, a new strategy for a reliable methodology regarding the antimicrobial testing of oriented fibre-based polymers such as cellulose is discussed, which could also be useful within several other polymer industrial fields

The model of entry strategies on the market for identification documents in Africa

V zadnjih letih pospešena krepitev globalizacije in liberalizacija trgovine zahtevata od podjetij vključevanje in konkuriranje na globalnem trgu, z namenom izkoriščanja tržnih priložnosti za doseganje večje prodaje in dobička. Strateško zasnovana prisotnost na tujih trgih omogoča podjetjem ne le obstoj, temveč tudi rast in dinamičen razvoj. Pri tem pa se postavlja vprašanje izbire ustrezne strategije vstopa na tuji trg, kar je odvisno ne samo od zaznanih priložnosti in nevarnosti v okolju, temveč tudi od sposobnosti podjetja za ustvarjanje in učinkovito razporejanje resursov ter od opredeljene strategije rasti podjetja. Grafično podjetje Cetis se tega zaveda, zato skuša svoje prodajne aktivnosti razpršiti na vse štiri kontinente na področju prodaje celovitih rešitev identifikacijskih dokumentov, predvsem pa na afriške trge, in sicer zaradi manjše zasičenosti trgov. Z izbrano temo magistrskega dela bi želeli pomagati podjetju Cetis pri učinkovitem vstopu in razvoju tržne pozicije na afriških trgih. Namen raziskave v magistrskem delu je bil ugotoviti ustreznost uporabljenih strategij vstopa na izbrane afriške trge in spoznati potrebno prilagajanje strategij razvoja tržne pozicije zahtevam trga pri prodaji celovitih rešitev izdaje identifikacijskih dokumentov, in sicer zaradi tržnih in institucionalnih specifičnosti vsakega posameznega nacionalnega trga. Z raziskavo smo skušali tudi razumeti interese in vplive lokalnih institucionalnih akterjev na dodeljevanje poslov in proces trženja ter ugotoviti, kako tehnološka razvitost trga in povezovanje podjetij v ponudbene koalicije vplivata na prodajni uspeh. Rezultati raziskave so pokazali, da je vsak lokalni afriški trg specifičen, zato zahteva prilagojen tržni nastop že ob vstopu in razvoju začetne tržne pozicije, ter da je v vseh afriških državah prisotna visoka stopnja korupcije in s tem specifični subjektivni vpliv posameznih akterjev na dodeljevanje poslov. Ugotovljeno pa je bilo tudi, da se pri prodaji na tistih afriških trgih, ki so v fazi enostavne tehnološke razvitosti, lažje dosegajo večji prodajni uspehi, kot če bi prodajali na trgih visoke tehnološke razvitosti. Pri tem je povezovanje z lokalnimi partnerji na posameznem afriškem trgu v ponudbene koalicije nujnost, v nasprotju s povezovanjem s konkurenčnimi podjetji, saj ostaja grafično podjetje, zaradi svoje majhnosti, neprepoznavno na trgu.In recent years, increasing globalization and trade liberalization require from companies the incorporation and competition in the global market in order to exploit market opportunities for achieving higher net sales revenues and profits. The above mentioned presence in foreign markets enables the existence, growth and development of companies. This raises the question of choosing an appropriate entry strategy for the foreign market, which depends not only on perceptual opportunities and dangers in the environment, but also on the ability of companies to create and efficiently allocate the resources and to define the growth strategy of the company. The graphic company Cetis is aware of that and therefore tries to disperse its sales activities on four continents in the field of selling complete solutions for identification documents, particularly in the African markets, due to lower saturation of these markets. We would like to help the company Cetis to effectively enter and develop its market position in the African markets with the chosen theme of this Master’s degree thesis. The purpose of the research in this Master’s degree thesis was to determine the adequacy of used entry strategies in selected African markets and to meet the necessary adjustment strategies for the development of market position and the market for selling complete solutions of issuing identification documents, because of market and institutional specificities of each national market. With the research we wanted to understand the interests and impacts of local institutional actors on getting the contracts and the marketing process, and to find out how the technological development of the market and the integration of companies in the bid coalitions, impact on the sales success. The results of the research showed that each local African market is specific and requires an adjusted market performance by entering and developing the initial market position, and that in all African countries there is a high degree of corruption and the specific subjective impact of individual actors on getting the contracts. It was also found out that by selling in the those African markets, which are at the stage of simple technological development, greater sales successes are achieved than by selling in the markets of high technological development. That’s why it is necessary for the local partners to integrate in the individual African market into a bid coalition, as opposed to integrating with its competitors, because the graphic company, due to its smallness, remains unrecognizable in the marke

Cellulose–Chitosan Functional Biocomposites

Here, we present a detailed review of recent research and achievements in the field of combining two extremely important polysaccharides; namely, cellulose and chitosan. The most important properties of the two polysaccharides are outlined, giving rise to the interest in their combination. We present various structures and forms of composite materials that have been developed recently. Thus, aerogels, hydrogels, films, foams, membranes, fibres, and nanofibres are discussed, alongside the main techniques for their fabrication, such as coextrusion, co-casting, electrospinning, coating, and adsorption. It is shown that the combination of bacterial cellulose with chitosan has recently gained increasing attention. This is particularly attractive, because both are representative of a biopolymer that is biodegradable and friendly to humans and the environment. The rising standard of living and growing environmental awareness are the driving forces for the development of these materials. In this review, we have shown that the field of combining these two extraordinary polysaccharides is an inexhaustible source of ideas and opportunities for the development of advanced functional materials

Composite materials based on waste chicken feather fibers for oil-spill management

Oil spills remain one of the greatest man-made ecological threats, despite numerous advanced cleanup approaches. They still pose a major challenge in the search for materials and technologies that work as efficiently and sustainably as possible. Promising natural materials include poultry feathers, which are produced in large quantities every day as a byproduct of the meat industry. In this study, the influence of different forms of absorbents (loose feathers, pillows, and sheets) based on chicken feathers and the addition of an inorganic absorbent, sepiolite, on their absorption capacity was investigated. The chemical and physical surface properties, like morphology, chemical composition, zeta potential, surface free energies and oil absorption capacities were analyzed. The Gibbs free energy of immersion wetting with oil and the work of adhesion of the adsorbents, calculated based on contact angle measurements, were confirmed by the tests of adsorption capacities according to the ASTM 726–12 standard. The results showed that pure loose feathers have the highest oil adsorption capacity, while feather pillows have only half, and composite sheets have only a quarter of this capacity. The addition of inorganic adsorbent sepiolite did not increase the absorption capacity of the composites

Cellulose–Chitosan Functional Biocomposites

Here, we present a detailed review of recent research and achievements in the field of combining two extremely important polysaccharides; namely, cellulose and chitosan. The most important properties of the two polysaccharides are outlined, giving rise to the interest in their combination. We present various structures and forms of composite materials that have been developed recently. Thus, aerogels, hydrogels, films, foams, membranes, fibres, and nanofibres are discussed, alongside the main techniques for their fabrication, such as coextrusion, co-casting, electrospinning, coating, and adsorption. It is shown that the combination of bacterial cellulose with chitosan has recently gained increasing attention. This is particularly attractive, because both are representative of a biopolymer that is biodegradable and friendly to humans and the environment. The rising standard of living and growing environmental awareness are the driving forces for the development of these materials. In this review, we have shown that the field of combining these two extraordinary polysaccharides is an inexhaustible source of ideas and opportunities for the development of advanced functional materials

Fibrillation of Lyocell fibres due to different treatment conditions

Razlike procesov pridobivanja različnih regeneriranih celuloznih vlaken povzročajo različno morfološko zgradbo vlaken, ki se kaže tudi v različnem nagnjenju k fibriliranju. Zaradi visoke orientacije in kristalinosti vlaken kažejo liocel vlakna močno težnjo k fibriliranju, t.j. cepljenju fibrilov vzdolž vlaken. Nabrekanje in mehanske obremenitve ta pojav pospešijo in ojačajo. Zelo tanki fibrili na površini vlaken in njihovo kodranje povzročijo povečano površino vlaken in s tem spremembo površine tkanin. Metoda, ki so trenutno na razpolago za ocenitev stopnje fibriliranja so še nepopolne. Spremembo površine vlakna kot funkcijo fibriliranja lahko zaznamo optično ali po spremembah otipa. V prispevku smo predstavili novo metodo zasledovanja fibriliranja s spremembo optičnih lastnosti tkanin, in sicer Tencel vlaken. Z obdelavo in kvantitativno analizo mikroskopskih slik smo določali spremembe oblike in velikosti por v tkanini, ki so nastale kot posledica različnih postopkov obdelane, n. pr. fibriliranje surove tkanine, encimatska obdelava in zamreženje liocel vlaken.The differences in the man-made cellulose fibre forming processes produce some varieties in the morphological structure of fibres, which shows in fibres\u27 different tendency to fibrillate, i.e. to split along the fibre axis. The basic parameters connected with the high degree of crystallinity and orientation of lyocell fibres are also the reason for lyocell fibres\u27 high tendency to fibrillate. Fibre swelling and mechanical stress promote this effect. Very fine fibrils on the fibre surface and their crimping increase the fibre surface and thereby influence the surface changes of the fabric. Some methods for following the formation of fibrils, their density and homogeneity have been proposed, but have proved to be insufficient. The changes of the fibre surface due to fibrillation can be followed optically or by handle changes. In the paper a new method for observing the changes of optical properties of lyocell fibres influenced by fibre fibrillation is given. The analyses were performed on Tencel fabrics. Processing and quantitative analysis of microscopic images was involved for studying the form and dimensions of fabric pores that were produced by different treatments, like raw fabric fibrillation, enzyme treatment and crosslinking of lyocell fibres

Attenuation of cerebral vasospasm in rabbits using clonidine hydrochloride, a central adrenergic agonist

The aim of this study was to assess, firstly, if exclusion of central noradrenergic areas in the hypothalamus and brain stem with the central sympathetic blocker clonidine hydrochloride could prevent the development of chronic vasospasm following experimental subarachnoid haemorrhage in rabbits and, secondly, if, parallel with the effect on cerebral arteries, changes in dopamine -hydroxylase concentration in the hypothalamus and brain stem could also be detected. Experimental subarachnoid haemorrhage, in concentrations of 1 ml of autologous arterial bloodž1 kg of body weight was carried out on 18 New Zealand rabbits. Histological specimens were obtained by the method of perfusion fixation after the rabbits were sacrificed on day 8 after subarachnoid haemorrhage. The spastic effect of experimentally induced subarachnoid haemorrhage was determined by assessing the intensity of corrugation of the intima of the rabbit basilar artery by the previously developed method of corrugation coefficient and computer image analysis. The concentration and localization of dopamine -hydroxylase in noradrenaline-containing neurons was immunohistochemically assessed (semiquantitatively as 0, 1 and 2) with anti-dopamine -hydroxylase, at precisely defined sites of the hypothalamus and brain stem of the same rabbit. The results revealed less corrugated and smoother intima in the basilar artery and significantly lower dopamine -hydroxylase concentration in the control group of rabbits with sham subarachnoid haemorrhage and without any additional interventions (mean corrugation COEFFICIENT=1.123 0.024, P=0.3510-3č mean dopamine -hydroxylase=0.350 0.071, P=0.22 10-3), and smootherintima in the basilar artery with significantly lower concentration ofdopamine -hydroxylase in the clonidine group (rabbits with subarachnoid haemorrhage and central 2-blocker clonidine hydrochloride at a daily dose of 0.03 mgžkg of body weight for 8 daysč mean corrugation COEFFICIENT=1.177 0.058, P=1.7 10-3č mean dopamine -hydroxylase=0.583 0.175, P=1.1 10-3). In comparison, the haemorrhage only group (rabbits with subarachnoid haemorrhage and without medicationč mean corrugation COEFFICIENT=1.370 0.101č mean dopamine -hydroxylase=1.214 0.313) displayed intensive corrugation of the intima of the basilar artery and a significantly more intensive accumulation of dopamine -hydroxylase than did the control group and the clonidine group. The results of this study demonstrated that the central 2-blocker clonidine hydrochloride effectively prevents vasospasm, and diminishes the concentration of cerebral dopamine -hydroxylase in the hypothalamus and brain stem after experimental subarachnoid haemorrhage in rabbits

Substrate-induced coagulation (SIC) of nano-disperse titania in non-aqueous media : the dispersibility and stability of titania in N-methyl-2-pyrrolidinone

Dispersions of 1 wt% titandioxide (titania or TiO2) were investigated with respect to their stability in non-aqueous media. The objective of this work was to find conditions for the substrate-induced coagulation (SIC) process in N-methyl-2-pyrrolidinone (NMP). The SIC process is a dip-coating process that enhances adsorption of fine dispersed particles on a pre-conditioned surface. The wetting behavior of titania and NMP was investigated by the powder contact angle method. The absorption process of the polar solvent NMP on the acid oxide TiO2and Aerosol OT (AOT) (bis-2-ethylhexyl sodium sulfosuccinate) was also investigated and a polar or hydrophilic interaction was found. The stability of titania in NMP dispersions and the influence of the solvent AOT and the electrolyte LiCl was investigated. By studying the electrophoretic mobilities of titania particles in NMP and the influence on solutes by the electrophoretic method phase analysis light scattering (PALS) and the electroacoustic method this paper explores suitable conditions for non-aqueous substrate-induced coagulation of titania