Chitosan Oligomer as a Raw Material for Obtaining Polyurethane Foams.

Decreasing oil extraction stimulates attempts to use biologically available sources to produce polyols, which are the basic components for obtaining polyurethane foams. Plants are inexhaustible source of oils, sugars, starches, and cellulose. Similar substrates to obtain polyols are chitosans. Commercially available modified chitosans are soluble in water, which gives them the possibility to react with hydroxyalkylating agents. We used a water-soluble chitosan previously to obtain polyols suitable for producing rigid polyurethane foams. Here, we described hydroxyalkylation of a low-molecular-weight chitosan (oligomeric chitosan) with glycidol and ethylene carbonate to obtain polyols. The polyols were isolated and studied in detail by IR, 1H-NMR, and MALDI-ToF methods. Their properties, such as density, viscosity, surface tension, and hydroxyl numbers, were determined. The progress of the hydroxyalkylation reaction of water-soluble chitosan and chitosan oligomer with glycidol was compared in order to characterize the reactivity and mechanism of the process. We found that the hydroxyalkylation of chitosan with glycidol in glycerol resulted in the formation of a multifunctional product suitable for further conversion to polyurethane foams with favorable properties. The straightforward hydroxyalkylation of chitosan with glycidol was accompanied by the oligomerization of glycidol. The hydroxyalkylation of chitosan with glycidol in the presence of ethylene carbonate was accompanied by minor hydroxyalkylation of chitosan with ethylene carbonate. The chosen polyols were used to obtain rigid polyurethane foams which were characterized by physical parameters such as apparent density, water uptake, dimension stability, heat conductance, compressive strength, and heat resistance at 150 and 175 °C. The properties of polyurethane foams obtained from chitosan-oligomer and water-soluble-chitosan sources were compared. Polyurethane foams obtained from polyols synthesized in the presence of glycerol had advantageous properties such as low thermal conductivity, enhanced thermal resistance, dimensional stability, low water uptake, and high compressive strength, growing remarkably upon thermal exposure.

Polyols and Polyurethane Foams Based on Water-Soluble Chitosan.

At present, majority of polyols used in the synthesis of polyurethane foams are of petrochemical origin. The decreasing availability of crude oil imposes the necessity to convert other naturally existing resources, such as plant oils, carbohydrates, starch, or cellulose, as substrates for polyols. Within these natural resources, chitosan is a promising candidate. In this paper, we have attempted to use biopolymeric chitosan to obtain polyols and rigid polyurethane foams. Four methods of polyol synthesis from water-soluble chitosan functionalized by reactions of hydroxyalkylation with glycidol and ethylene carbonate with variable environment were elaborated. The chitosan-derived polyols can be obtained in water in the presence of glycerol or in no-solvent conditions. The products were characterized by IR, 1H-NMR, and MALDI-TOF methods. Their properties, such as density, viscosity, surface tension, and hydroxyl numbers, were determined. Polyurethane foams were obtained from hydroxyalkylated chitosan. The foaming of hydroxyalkylated chitosan with 4,4'-diphenylmethane diisocyanate, water, and triethylamine as catalysts was optimized. The four types of foams obtained were characterized by physical parameters such as apparent density, water uptake, dimension stability, thermal conductivity coefficient, compressive strength, and heat resistance at 150 and 175 °C. It has been found that the obtained materials had most of the properties similar to those of classic rigid polyurethane foams, except for an increased thermal resistance up to 175 °C. The chitosan-based polyols and polyurethane foams obtained from them are biodegradable: the polyol is completely biodegraded, while the PUF obtained thereof is 52% biodegradable within 28 days in the soil biodegradation oxygen demand test.

Bilateral choroidal melanoma--case analysis and literature review.

Uveal melanoma is the most common primary intraocular neoplasm in adults. Its bilateral localization is extremely rare. The aim of the paper is analysis of the cases of bilateral uveal melanoma. Five bilateral uveal melanoma patients were diagnosed in the Department of Ophtalmology and Ocular Oncology beetwen 1980 and 2014. Both eyes of four patients were threated with brachytherapy. Final enulcleation of the one eye was performed in three patients. It was the primary treatment in one patient. The presence of uveal melanoma was confirmed by pathological examination in all cases after surgical removal of eyeball and in one after local resection of iris tumor. Metastatic lesions were diagnosed in lungs and liver in two patients. Three patients are still followed-up at our institution. The possibility of bilateral uveal melanoma should considered although it is extremely rare. bilateral uveal melanoma, brachytherapy, enucleation.

[Abnormal pupils' reactions]. / Nieprawidlowe reakcje zreniczne.

Examination of the pupils' light reaction and estimation of the pupils' diameter are the components of the routine physical examination of a patient. Disturbances in pupils' light reaction, unequal size of the pupils indicate damage of the nervous system and require careful diagnosis, both neurological and ophthalmological. Different aspects of anatomy, physiology and the most common pathological syndromes associated with disturbed pupils' light reaction and unequal diameters of the pupils were presented in the article. Early diagnosis and proper treatment can allow to improve prognosis in the analyzed patient group.

[Cataract in an atopic dermatitis patient--case report and review of the literature]. / Zacma u chorego z atopowym zapaleniem skóry--opis przypadku i przeglad pismiennictwa.

Atopic cataract is one of several kinds of presenile cataracts, which develops in 20% of patients suffering from atopic dermatitis. Atopic cataract is the most frequently bilateral and characterized by fast progression. This type of cataract creates more and more important social problem, because of the young age of patients, who are usually professionally active and increasing incidence of atopic dermatitis in population. The aim of this paper is to present the case report of the atopic cataract in patient who was operated in the Regional Ophthalmologic Hospital in Krakow, and the review of the literature.