Radioactivity characterization of 125I brachytherapy seeds used in prostate cancer treatment

Journal of Radioanalytical and Nuclear Chemistry - A procedure for characterizing the activity amount of 125I seed was developed in order to establish a secondary standard activity measurement...     

Some aspects of acylation of cellulose under homogeneous solution conditions

Commercially available cellulose (Avicell PH101) was successfully acylated under homogeneous solution conditions by the following procedure: 2.0 g of cellulose were stirred with 75 mL of N,N‐dimethylacetamide for 1 h at 150°C, 3.5 g of LiCl were added, the temperature was raised to 170°C, ca. 18.5 mL of the solvent were distilled and the suspension was cooled to room temperature and stirred overnight. The temperature of the clear cellulose solution was raised to 110°C, kept at that temperature for 1 h, an acid anhydride was added and the solution stirred at 110°C for additional 4 h. Acetates, propionates, butyrates, and acetate/propionate mixed ester were prepared with excellent control of the degree of substitution, DS, 1 to 3 for acetates, 2 and 3 for propionates and butyrates, and 3 for acetate/propionate. The degree of polymerization of cellulose is negligibly affected under these reaction conditions. The distribution of the acetyl moiety among the three OH groups of the anhydroglucose unit shows a preference for the C₆ position. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1357–1363, 1999     

CI Reactive Black 5 dye as a visible crosslinker to improve physical properties of lyocell fabrics

Bi-functional reactive dyes have been used for reducing the fibrillation of lyocell fibres. The sole influence of CI Reactive Black 5 dye on the fibrillation tendency of lyocell single jersey knitted fabrics was investigated by dyeing with different concentrations (35 g/L for medium shade and 70 g/L for dark shade), dyeing without dyestuff and by decolouration process after each dyeing. The fibrillation tendency of lyocell fibres was accessed by means of fibre wet abrasion resistance and fibrillation number. Nitrogen content was used as indication of the amount of reactive dye in fabrics during dyeing and decolouration processes. The correlation between fibre fibrillation tendency and colour values of fabrics was found. Due to the fibrillation reduction, pilling formation in dyed lyocell fabrics was improved. As colour values can estimate the dye fixation and reduction in fabrics, reactive dye can be used as a visible marker for crosslinking effect on lyocell fabrics.     

Treatment in Swelling Solutions Modifying Cellulose Fiber Reactivity – Part 1: Accessibility and Sorption

Of prime importance in reactions involving insoluble cellulosic fibers is the sorption of reagents, which is governed by their degrees of accessibility in substrates. Swelling treatments of cellulosics in alkali solutions alter substrate accessibility leading to changes in their reactivity. In this paper, the first of a two-part series, we collate and examine the results from various studies involving different techniques to characterize modifications in cellulosic fibers after swelling treatments in alkali solutions. Results from measurements of structure and accessibility in fibers with techniques such as water retention, inverse size exclusion chromatography (ISEC), iodine sorption, fiber diameters, and fiber-splitting propensities indicate that the influence of swelling treatments on fiber structure/accessibility is differs with alkali type. The results show that a non-uniform rather than uniform distribution of reagents within structures is a more accurate representation of reactions involving swollen cellulosic fibers. Hence, the observed changes in cellulose-fiber reactivity are governed by the degrees of fiber swelling, and reagent sorption and accessibility during swelling treatments.     

Characterization of Catalysts for Glycerol Ester Production with Various Acetylating Agents

The use of raw materials from renewable sources by industries is essential to the sustainable development of modern society. The biodiesel produced by the transesterification of vegetable oils is a less polluting diesel fuel, but large amounts of glycerol (10% of total weight of product) are generated during the production process. The scientific community and industries of the sector know that, in the future, the amount of glycerol generated can cause a serious ecologic problem. Thus, it is essential to find alternatives for the consumption of this co-product, in its crude form and/or as high value-added derivatives. This work studied obtaining triacetate from the glycerol esterification reaction that was determined by electrospray ionization–mass spectrometry and gas chromatography–mass spectrometry. The reactions were carried out with sulfuric acid, phosphotungstic acid and in the absence of catalyst, using different acetylating agents (acetic acid and acetic anhydride). The phosphotungstic acid showed satisfactory performance in the catalytic esterification of glycerol when acetic acid and acid anhydride were used. The use of acetic anhydride as the acetylating agent favors the esterification reaction, decreasing the reaction time required for obtaining glycerol triacetate.     

A Voltammetric Approach for the Simultaneous Determination of Cd and Pb in Water Applying Carbon Paste Electrode Modified with Bismuth Film

Journal of Analytical Chemistry - This study reports the simultaneous voltammetric determination of Cd and Pb by square wave voltammetry (SWV) using carbon paste electrode modified with bismuth...     

Use of bacterial cellulose in the textile industry and the wettability challenge—a review

Bacterial cellulose (BC) has been studied as an alternative material in several segments of the food, pharmaceutical, materials and textile industries. The importance of BC is linked to sustainability goals, since it is an easily degradable biomaterial of low toxicity to the environment and is a renewable raw material. For use in the textile area, bacterial cellulose has attracted great interest from researchers, but it presents some challenges notably to its hydrophilic structure. This integrative review article brings together studies and methods related to minimizing the hydrophilicity of bacterial cellulose, in order to expand its applicability in the textile industry in its dry state. The databases consulted were Scopus, ScienceDirect, ProQuest and Web of Science, the documents investigated were scientific articles and the time period investigated was between 2015 and 2021. The results showed that although there are methods to make the BC membrane more hydrophobic, future studies in this regard and on other properties must continue so that bacterial cellulose can be commercially introduced in the textile sector.

     

Cellulose derivatives as solid electrolyte matrixes

Cellulose derivatives like hydroxyethylcellulose (HEC) and carboxymethylcellulose (CMC) were submitted to the graftization reactions. The samples of HEC were grafted with monoisocyanate of poly(propylene oxide) (MPPO) and different diisocyanates of poly(ethylene oxide) (DPEO) and poly(propylene oxide) (DPPO) in the presence of LiClO₄. CMC was grafted with MPPO. These polyssacharides based samples were characterized by IR, NMR and thermal analysis (DSC and TGA). The samples of grafted polyssacharides derivatives showed glass transition temperatures (Tg) of −40°C for HEC/MPPO, −33°C for HEC/DPEO, −10°C for HEC/DPPO and 24�C for CMC/MPPO. The ionic conductivities of all samples were about 10⁻⁷‐10⁻⁶ S/cm at room temperature. The sample of CMC/MPPO presented conductivity value similar to HEC/DPPO but does not exhibit film‐forming characteristic indicating its use as solid polymer electrolytes only in the pellet form.