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1

Evaluation of the strength properties of materials intended for tracheobronchial tubes

Sobota Robert, Markowski Jarosław, Joszko Kamil, Gzik-Zroska Bożena, Kawlewska Edyta, Gzik Marek

Engineering of Biomaterials

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2020

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Vol. 23, no. 156

10--16

EN

The desire to increase the comfort of patients and to continue production despite the decreasing amount of available materials on the market has led to the constant search for novel materials that could be used to obtain tracheobronchial tubes. The aim of this study is to determine the mechanical properties of a new thermoplastic elastomer. Two materials - the thermoplastic elastomer and the natural rubber were subjected to three tests: static tensile test, static compression test and static three-point bending test. During the static tensile test, samples of the tested materials were examined, and during the next two examinations, the final products. The materials underwent the processes of sterilization, hydrolytic degradation and degradation by oxidation. The treated samples were also tested in order to compare the obtained results. The mechanical properties of the tested materials improved both after the hydrolytic degradation and oxidative degradation, as well as after the sterilization process. Yet the thermoplastic elastomer revealed a more noticeable increase. The elastomer hardening is a positive phenomenon potentially leading to fewer accidental closures of the tubes cross-section. Both the sterilization process and various degradation methods improved the mechanical properties by strengthening the tested materials. This phenomenon seems to be desirable to avoid the closure of the implemented tube during its application.

2

Degradation of p-aminophenol by Fenton’s process. Influence of operational parameters

Ghosh P., Ghime D., Lunia D.

Environment Protection Engineering

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2017

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Vol. 43, nr 3

255--267

EN

Oxidative degradation of a model environmental pollutant, p-Aminophenol (PAP), in aqueous solution has been investigated in an environmentally friendly advanced oxidation Fenton process. Effects of various operating parameters such as pH of solutions, dosage of hydrogen peroxide and ferrous ions, initial PAP concentration and temperature on the degradation of PAP have been studied using a batch stirred ceil. Degradation kinetics for this pollutant was also investigated to determine the apparent rate constants (min-1)- The optimum conditions for the degradation of PAP solution (200-500 mg/dm3) were found to be pH = 3.0, 2400 mg H2O2dm, 300 mg Fe2+/dm3, 30°C. Under the optimum conditions, the degradation efficiency of PAP was 75% after 50 min of reaction. It was observed that process parameters play a major role in the overall degradation process.

3

Metody określania struktury polisacharydów

Samaszko-Fiertek J., Kuźma M., Dmochowska B., Ślusarz R., Madaj J.

Wiadomości Chemiczne

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2016

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[Z] 70, 5-6

299--318

EN

Sequencing of polysaccharides is difficult to achieve because of the heterogeneous nature of the polysaccharide structure, high molecular weight (the size of a polysaccharide varies between approximately 16,000 and 16,000,000 daltons (Da)), and polydispersity of the polymer chains. The following information is essential to determine the primary structure of a polysaccharide: • monosaccharide composition: nature and molar ratios of the monosaccharide building blocks; • relative configuration of monosaccharides: d or l; • anomeric configuration: α- or β-configuration of the glycosidic linkage; • ring size: presence and distinction of furanosidic and pyranosidic rings; • linkage patterns: linkage positions between the monosugars and branches; • sequences of monosaccharide residues in the repeating units; • substitutions: position and nature of OH–modifications, such as O–phosphorylation, acetylation, O-sulfation, etc.; • molecular weight and molecular weight distribution. A polysaccharide extracted from plant materials or food products is usually purified before being subjected to structural analysis. The first step of characterizing a polysaccharide is the determination of its purity, which is reflected by its chemical composition, including total sugar content, level of uronic acids, proteins, ash, and moisture of the preparation. The second step is the determination of monosaccharide composition, which will unveil structural information such as the number of monosaccharides present in the polysaccharide and how many of each sugar unit. NMR spectroscopy has become the most powerful and noninvasive physicochemical technique for determining polysaccharide structures. It can provide detailed structural information of carbohydrates, including identification of monosaccharide composition, elucidation of α- or β-anomeric configurations, establishment of linkage patterns, and sequences of the sugar units in oligosaccharides and/or polysaccharides. Monosaccharide composition can be determined also by analysis of totally acid hydrolyzed polysacharide using high performance liquid chromatography (HPLC) or gas chromatography (GC). The ring size and glycosidic linkage positions of sugar units in a polysaccharide could be established by methylation analysis and/or cleavage reduction. The anomeric configuration is conventionally determined by oxidation, and this method can be combined with mass spectrometry to obtain more structural information.

4

Semi-preparative isolation and characterization of a principal oxidative degradation product in galantamine hydrobromide by LC-ESI-MSn and 2D-NMR

Thomas S., Paul S. K., Agarwal A., Mathela C. S.

Acta Chromatographica

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2014

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Vol. 26, no. 3

429--438

EN

Galantamine hydrobromide was subjected to oxidative stress degradation using hydrogen peroxide and analyzed as per the chromatographic conditions described in European Pharmacopoeia. The drug showed considerable degradation at ambient temperature resulting in the formation of two degradation products at relative retention times (RRTs) 0.63 and 2.52. The minor degradant at RRT 0.63 was identified as galantamine N-oxide. The principal degradant formed at RRT 2.52 was found to be unknown and has not been reported previously. The unknown impurity was identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) followed by isolation using semi-preparative high-performance liquid chromatography (HPLC). The isolated impurity was characterized using one-dimensional, two-dimensional nuclear magnetic resonance spectroscopy (1D and 2D NMR) and elemental analysis (EA). The principal degradant was found to be formed due to the generation of bromine and subsequent attack on the aromatic ring via in situ reaction between hydrogen bromide and hydrogen peroxide. The unknown impurity was characterized as (4aS,6R,8aS)-5,6,9,10,11,12-hexahydro-1-bromo-3-methoxy-11-methyl-4aH-[1]benzofuro [3a,3,2-ef] [2] benzazepin-6-ol.

5

Study of the solid phase catalytic oxidation of polypropylene

Zawadiak J., Marek A. A., Nokielski A.

Polish Journal of Applied Chemistry

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2010

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Vol. 54, nr 1-4

1-9

EN

The solid phase catalytic oxidative degradation of isotactic polypropylene was studied. The influences of the type and amount of catalyst, temperature, and type of oxidising agent on the oxidative degradation were investigated. Iron(III), manganese(II), cobalt(II), vanadium(III), copper(II) and nickel(II) acetylacetonates were used as catalysts. The obtained products were characterised by the determination of acid number, saponification number and melting range as an index of the degradation progress.