Cationic polyelectrolytes,XII. PEG-precursor for water-soluble cationic polymers with tertiary n-atoms in the main chain

Water-soluble cationic polymers were obtained by polyaddition of poly(ethylene glycol) (PEG) diglycidylethers (M?_n of PEG were 396, 587, 1437 and 3554, resp.) with asymmetrical diamines such as N,N-dimethyl-1,3-diaminopropane and N,N-diethyl-1,3-diaminopropane. The cationic polymer properties depend on the PEG initial molecular weight and on the diamine reactivity too. PEG with M?_n = 396 had the best behaviour in these reactions. The polyelectrolyte feature of cationic polymers was emphasized both in dilute aqueous solutions and in 2M aqueous NaCl solutions. The polyelectrolyte behaviour in 2M aqueous NaCl solution is determined by the PEG chain presence.     

Influence of melt processing on biodegradable nisin‐PBAT films intended for active food packaging applications

Biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) films incorporated with different levels of the antimicrobial peptide nisin were developed by melt processing. Structural, morphological, thermal, mechanical, and antimicrobial properties of the films were determined. The X‐ray diffraction patterns exhibited decreasing levels of intensity at 2θ values as the concentration of nisin increased. Scanning electron microscopy showed a heterogeneous morphology when higher amounts of nisin were incorporated. The antimicrobial films tested presented no significant differences in the melting temperature (123–125°C), and the crystallization temperature ranged from 69 to 75°C. The addition of nisin caused no significant modification in tensile strength values. However, results of Young's modulus and deformation at break differed significantly among samples. Active films demonstrated inhibition against the Gram‐positive bacterium Listeria monocytogenes. These results demonstrated that PBAT/nisin films produced by melt processing present a great potential for use as active food packaging materials aiming enhanced food safety. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43212.     

Interaction of dis‐azo dyes with quaternized poly(dimethylaminoethyl methacrylate) as a function of the dye structure and polycation charge density

Interactions between some dis‐azo dyes, different by either the position of their sulfonic groups or their number (Ponceau SS, Crocein Scarlet MOO, Congo Red, and Direct Blue 1), and some strong polycations (PCs), with cationic centers in their side chains and dye removal from artificial wastewaters were systematically investigated in this study. PCs with variable charge densities (CDs) were prepared from poly(dimethylaminoethyl methacrylate) by controlled quaternization with benzyl chloride. Even when the main process in the dye removal was charge neutralization (coagulation) for all of the dyes, significant effects of the CD and dis‐azo dye structure on the metachromatic behavior of the dyes in dilute aqueous solutions and on the dye removal efficiency were observed. The stability of the PC/azo dye complex and, connected with this, the flocculation window were higher when the PC with the highest CD was used. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Heavy metals adsorption on some iminodiacetate chelating resins as a function of the adsorption parameters

The adsorption properties of some novel chelating resins (CRs) bearing iminodiacetate groups for removal of heavy metal ions like: Cu(II), Co(II) and Ni(II) from aqueous solutions comparative with the commercial resin Amberlite IRC-748 have been studied in this work by a batch equilibrium technique. Quantitative analysis for adsorption was conducted using UV–vis spectroscopy to investigate the kinetics, adsorption isotherm and thermodynamics of the removal process considering equilibration time, pH, metal ion concentration and temperature as controlling parameters. The metal adsorption capacities, at pH 5, were in the order Cu(II) > Ni(II) > Co(II), for both the CR with 10 wt.% DVB (CR-10) and the commercial resin Amberlite IRC-748. The adsorption capacities on CR-10 were higher for Ni(II) and Co(II) ions, but lower for Cu(II) ions compared with Amberlite IRC-748. Both Freundlich and Langmuir isotherms well fitted on the adsorption results of Cu(II), Ni(II) and Co(II) ions on all iminodiacetate resins.     

Clavaria Mushrooms and Extracts: Investigation on Valuable Components and Antioxidant Properties

Two Clavaria mushrooms were investigated as sources of antioxidant compounds, essential trace elements Selenium and Zinc, and as efficient antioxidants in elimination/inhibition of different radical species. Using HPLC method, pistillarin-rare siderphore compound characterized with high antioxidant activity, was detected in both extracts. A higher content of pistillarin has been measured in C. pistillaris extract. The same extract contained the higher content of Selenium, 3.051μg/g. Both extracts showed important antioxidant activity. For C. pistillaris extract lower IC₅₀ value has been measured and higher antioxidant activity against O₂^? radical has been detected. Although the content of pistillarin was higher in the case of C. pistillaris, at the concentration of 0.2 mg/ml C. fennica extract showed just some higher antioxidant activity against ·OH radicals, 82 and 87%, respectively.     

Nitric oxide,an inhibitor of lipid oxidation by lipoxygenase,cyclooxygenase and hemoglobin

The present study demonstrated that nitric oxide, which is an important mammalian metabolite, can inhibit oxidation by lipoxygenase, cyclooxygenase and hemoglobin. The inhibition is manifested as a lag-phase that is reversible. The inhibitory effect of nitric oxide on lipoxygenase and cyclooxygenase seems to derive from i) the capability of ·NO to reduce the ferric enzyme to the ferrous form, which is inactive; ii) competition for the iron site available for exogenous ligands; and iii) the radical scavenging ability of the nitroxide radical. Nitric oxide may act as a modulator of the arachidonic acid cascade and in the generation of oxygen-active species.     

Flocculation of montmorillonite by some hydrophobically modified polycations containing quaternary ammonium salt groups in the backbone

The flocculating efficiency of some hydrophilic/hydrophobic cationic polyelectrolytes on montmorillonite suspension in water was investigated as a function of both the polycation structure and the flocculation parameters: polycation/montmorillonite contact time, suspension pH, polycation dose, and temperature. Cationic polyelectrolytes with quaternary ammonium salt groups in the backbone and hydrophobic side chains (hexyloxypropyl, PCA₅H₁ and PCA₅H₂; and decyloxypropyl, PCA₅D₁, respectively) were used as flocculants. The flocculation was time dependent. A negative influence of the stirring time and of the abrupt variation of pH from basic to acidic on the separation efficiency was evidenced. The increase of the polycation dose from 0.58 mg polycation/g montmorillonite up to 1.74 mg/g montmorillonite showed a positive influence on the sedimentation of montmorillonite particles for all the polycations taken into account. The influence of the polycation structure was reflected in the lower turbidity found in the case of the polycation PCA₅D₁ compared with that of PCA₅H₁, at the same concentration; this reflects the positive influence of the hydrophobicity increase on the suspension separation. A common characteristic for all the polycations is that, for more than about 60 min of settling, the lowest turbidity was found at 25°C and the highest at 5°C. The turbidity found at 15°C was in between, both before and after 60 min of settling time. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 871–876, 2002; DOI 10.1002/app.10371     

Organic–inorganic polymer hybrids and porous materials obtained on their basis

Tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS), an organic monomer [methylmethacrylate (MMA) or styrene (St)] and either α‐propylmethacryloxy‐ω‐trimethylsiloxy‐oligo(dimethylsiloxane) (OMS), as a compatibilizing agent, or α,ω‐bis(vinyl) oligo(dimethylsiloxane) (OVS), as compatibilizing and crosslinking agent, were allowed to undergo a sol–gel reaction under acidic condition and in the presence of 2,2′‐azoisobutyronitrile (AIBN) as a free‐radical initiator. The hydrolysis‐condensation and in situ free‐radical polymerization occur independently, to give a hybrid consisting of both inorganic and organic components. The conversion of the monomers to the proper polymers was monitored by IR spectroscopy and TGA. The resistance of the organic polymers to solvent extraction was also studied. The hybrids were pyrolyzed in an oxidative atmosphere. By decomposition, the organic polymer generated pores in the inorganic matrix. A quantitative evaluation of the characteristics for the resulting porous material was made by determination of the specific area, pore volume, and average radius. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2060–2067, 2003     

Mathematical Modeling of Ocimum basilicum L. Supercritical CO2 Extraction

The effects of pressure and temperature on supercritical extraction of Ocimum basilicum L. in terms of extraction yield and aromatic compounds were investigated. Linalool, eugenol, and δ‐cadinene were indentified as three main compounds of the prepared extracts. The dominant compound in all investigated supercritical basil extracts was linalool. Within the experimental range the extraction parameters had a significant influence on the extraction yield. The obtained results for the sweet basil total extract, cadinene, and linalool best matched with the Gordillo et al. model, therefore, the solubility of total extract, linalool, and cadinene in supercritical CO₂ at investigated temperatures is described as a function of pressure.     

Extraction of Fatty Acids from <Emphasis Type="Italic">Boletus edulis</Emphasis> by Subcritical and Supercritical Carbon Dioxide

Mushrooms contain many valuable compounds such as fatty acids, carbohydrates, lycopene, lovastatin, trace elements etc. As they are currently valued for biologically active substances, and as high pressure carbon dioxide fluid extraction has been documented as an effective method for preparing bioactive products from plant materials, subcritical and supercritical carbon dioxide extraction of Boletus edulis mushroom was performed. In the extracts obtained, the fatty acids were determined. Response surface methodology (RSM) was applied to investigate the effect of pressure and extraction time on the extraction yield. The analysis of variance showed that pressure and extraction time had a significant effect on the extraction yield in both investigated process. The interaction between pressure and extraction time had a significant effect only in supercritical extraction process of B. edulis. Higher extraction yields have been obtained by subcritical carbon dioxide, and higher linoleic acid content has been determined in extracts obtained by supercritical carbon dioxide.