Modification of porous copolymers network based on acrylonitrile

Summary The preparation of a chelating ion-exchange network based on acrylonitrile was carried out by chemical modification with hydroxylamine. The beads of resin were synthesized by aqueous suspension copolymerization of acrylonitrile (AN), styrene (STY) and divinylbenzene (DVB). The influence of diluent used in the suspension polymerization on the structure of the resulting copolymers was evaluated. The diluents employed were heptane (HEP), toluene (TOL) and anisole (ANI). It was found that the AN incorporation into copolymer structure was dependent on the diluent used. Conversion of nitrile groups into the amidoxime was conducted by treatment with hydroxylamine under alkaline solution. The resins were characterized by apparent density, surface area, average pore diameter, elemental analysis (CHN), FTIR and optical microscopy. Based on the results obtained, it was possible to control the porosity by diluent employed in the synthesis and to modify chemically a resin containing nitrile groups by hydroxylamine reaction. Received: 6 October 2001/Revised version: 2 April 2002/ Accepted: 11 April 2002     

Synthesis, Characterization, and Processing of Cordierite-Glass Particles Modified by Coating with an Alumina Precursor

The surfaces of cordierite and glass particles were modified by coating them with an alumina precursor using a precipitation process in the presence of urea. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy, X-ray diffraction, electrophoresis, and rheological measurements were used to characterize the coated powders. SEM and transmission electron microscopy morphologies of the coated powders revealed that amorphous and homogeneous coatings have been formed around the particles. The morphology of the coated powders showed a coiled wormlike surface. The coating Al₂O₃ layer dominated the surface properties of the coated glass and cordierite powders. The influence of the coating layer on the processing ability of cordierite-based glass-ceramics substrates by tape casting was studied in aqueous media. It could be concluded that the coating of the powders facilitates the processing and yields green and sintered tapes with denser, more homogeneous microstructures compared with the uncoated powders.     

The Impact of [C16Pyr][Amp] on the Aggressiveness in Breast and Prostate Cancer Cell Lines

Breast (BrCa) and prostate (PCa) cancers are the most common malignancies in women and men, respectively. The available therapeutic options for these tumors are still not curative and have severe side effects. Therefore, there is an urgent need for more effective antineoplastic agents. Herein, BrCa, PCa, and benign cell lines were treated with two ionic liquids and two quinoxalines and functional experiments were performed—namely cell viability, apoptosis, cytotoxicity, and colony formation assays. At the molecular level, an array of gene expressions encompassing several molecular pathways were used to explore the impact of treatment on gene expression. Although both quinoxalines and the ionic liquid [C2OHMIM][Amp] did not show any effect on the BrCa and PCa cell lines, [C16Pyr][Amp] significantly decreased cell viability and colony formation ability, while it increased the apoptosis levels of all cell lines. Importantly, [C16Pyr][Amp] was found to be more selective for cancer cells and less toxic than cisplatin. At the molecular level, this ionic liquid was also associated with reduced expression levels of CPT2, LDHA, MCM2, and SKP2, in both BrCa and PCa cell lines. Hence, [C16Pyr][Amp] was shown to be a promising anticancer therapeutic agent for BrCa and PCa cell lines.     

The Anti-Inflammatory Effects of the Methanolic Extract and Fractions from Davilla elliptica St. Hil. (Dilleniaceae) on Bothrops jararaca Envenomation

Inflammation and haemorrhage are the main characteristics of tissue injury in botropic envenomation. Although some studies have shown that anti-venom prevents systemic reactions, it is not efficient in preventing tissue injury at the site of the bite. Therefore, this work was undertaken to investigate the anti-inflammatory effects of the methanolic extract and fractions from D. elliptica and to evaluate the role of matrix metalloproteinases (MMPs) in this process. Effects of the extract and fractions from D. elliptica were evaluated using a carrageenan-induced paw oedema model in rats, and leukocyte rolling was visualized by intravital. The quantification of MMPs activities (MMP-2 and MMP-9) extracted from the dermis of mice treated with extract and fractions alone or incubated with venom was determined by zymographic analyses. Our results show that intraperitoneal (i.p.) injection of fractions significantly reduced paw oedema after the carrageenan challenge. Treatment with the tannins fraction also resulted in considerable inhibition of the rolling of leukocytes and this fraction was able to decrease the activation of MMP-9. These results confirmed the anti-inflammatory activity of the methanolic extract and tannins fraction of D. elliptica and showed that the dermonecrosis properties of B. jararaca venom might be mediated through the inhibition of MMP-9 activity.     

trans Fatty Acids in Colostrum,Mature Milk and Diet of Lactating Adolescents

The purpose of this study was to investigate the trans fatty acids (TFA) content and distribution in colostrum, mature milk, and diet of adolescent mothers, after TFA declaration in food labels became mandatory in Brazil. Participants were healthy adolescents (n 54, 15–19 years, 1–90 days postpartum) practicing exclusive breastfeeding. Milk samples were collected 3 days after delivery (colostrum) and in the third month postpartum (mature milk) by hand expression. The fatty acid composition of the milk samples was determined by gas chromatography. TFA intake corresponded to 1.23 % of total energy value. Total 18:2 TFA accounted for less than 0.5 % of the energy intake. The amount of total 18:1 TFA (mean ± SEM) was 1.9 % ± 0.14 in colostrum and 1.5 % ± 0.2 in mature milk. The total content of n‐3 PUFA was inversely correlated with the total content of 18:1 TFA in colostrum. Both in colostrum and in mature milk, vaccenic acid (11t‐18:1) was found to be the most abundant 18:1 trans isomer, followed by elaidic acid (9t‐18:1), whereas rumenic acid (9c,11t‐18:2 CLA) was the predominant 18:2 trans isomer. In conclusion, the levels of TFA of industrial sources found in the mother's diet and breast milk (colostrum and mature milk) showed a decrease in relation to those observed in studies conducted prior to the TFA labeling resolution in Brazil. However, the current low intake levels of n‐3 LCPUFA and DHA content in the milk of lactating adolescents may be insufficient for supporting adequate neurological development of the infants.     

Method for Characterization of Solvents for Physical Absorption Processes

A method for solvent screening and searching for additives in the field of physical absorption processes is presented. A model based on the concept of virtual components and on the concept of a simplified abstract flow sheet is created. An estimation procedure for thermodynamically consistent property sets for the virtual component is developed. The model is implemented into MATLAB®. Its application is demonstrated in two studies including a study for a solvent additive. Potential candidates can be characterized and ranges for properties of the solvent or additive are found by means of the model. Conclusions obtained from the model support the screening process by a reduction of the number of further investigated components.     

Ozone Treatment of Tannery Wastewater Monitored by Conventional and Substance Specific Wastewater Analyses

Ozone is an unstable and highly reactive gas applied in drinking water or wastewater treatment to oxidize and/or mineralize pollutants. Its application in wastewater treatment leads to a destruction of persistent pollutants combined with an improvement of biodegradability. The oxidation of organic and inorganic compounds in tannery wastewater at different pHs applying O₃ was studied. Results after O₃-treatment were determined by conventional wastewater parameters, e.g., total organic carbon (TOC), biochemical oxygen demand after 5 days (BOD₅), and chemical oxygen demand (COD), as well as by substance-specific mass spectrometric analytical techniques, i.e., gas chromatography—mass spectrometry (GC/MS) and liquid chromatography—mass and tandem mass spectrometry (LC/MS and—MSⁿ). In parallel, variations in the toxicity of the tannery wastewater against water organisms before and after O₃-treatment were determined by means of biotoxicity testing, i.e., Daphnia magna Straus and Vibrio fischeri bioassays.     

Kinetic and stoichiometric characterisation of streptavidin-binding aptamers

Aptamers are oligonucleotide ligands that are selected for high-affinity binding to molecular targets. Only limited knowledge relating to relations between structural and kinetic properties that define aptamer-target interactions is available. To this end, streptavidin-binding aptamers were isolated and characterised by distinct analytical techniques. Binding kinetics of five broadly similar aptamers were determined by surface plasmon resonance (SPR); affinities ranged from 35-375 nM with large differences in association and dissociation rates. Native mass spectrometry showed that streptavidin can accommodate up to two aptamer units. In a 3D model of one aptamer, conserved regions are exposed, strongly suggesting that they directly interact with the biotin-binding pockets of streptavidin. Mutational studies confirmed both conserved regions to be crucial for binding. An important result is the observation that the most abundant aptamer in our selections is not the tightest binder, emphasising the importance of having insight into the kinetics of complex formation. To find the tightest binder it might be better to perform fewer selection rounds and to focus on post-selection characterisation, through the use of complementary approaches as described in this study.     

Collection of soot particles into aqueous suspension using a particle-into-liquid sampler

Steam collection devices collecting aerosol particles into liquid samples are frequently used to analyze water-soluble particulate material. The fate of water-insoluble components is often neglected. In this work, we show that fresh soot particles can be suspended into pure water using a steam collection device, the particle-into-liquid sampler (PILS, Weber et?al. 2001). The overall collection efficiency of freshly generated soot particles was found to be on the order of 20%. This shows that, depending on the analytic technique employed, the presence of insoluble, and/or hydrophobic particles in liquid samples from steam collection cannot be neglected.

Copyright © 2018 The Author(s). Published with license by Taylor & Francis Group, LLC