Protein-precipitating capacity of bearberry-leaf (Arctostaphylos uva-ursi L. Sprengel) polyphenolics

Polyphenolics (PP) from bearberry (Arctostaphylos uva-ursi L. Sprengel) leaves were extracted with 70% (v/v) acetone. The lyophilised crude PP extract was then separated on a Sephadex LH-20 column using first 95% (v/v) ethanol as a mobile phase to elute fraction I low in tannins, and then 50% (v/v) acetone to elute fraction II rich in hydrolysable and condensed tannins. Bovine serum albumin (BSA) was effectively precipitated by PP in the bearberry-leaf crude extract and fraction II at pH values between 3.8 and 4.5. A statistically significant (P = 0.0001) linear relationship exists between the amount of PP-protein complex formed and the quantity of PP added to the reaction mixture. The slope values of these lines indicate that fraction II from the crude extract was a more effective precipitant of proteins than other examined preparations. Based on the quantity of gelatine, fetuin, and BSA required to inhibit 50% of dye-labelled PP–BSA complex precipitation, gelatine was 3–6 times more effective as a precipitation inhibitor than both unlabelled BSA and fetuin.     

Development of a nebulizer for a sheathless interfacing of NanoHPLC and ICPMS

A novel nebulizer (nDS-200) working at sample uptake rates of less than 500 nL min(-1) was developed for a sheathless interfacing of nanoHPLC (75-microm column i.d.) with ICPMS. It was based on a hollow fused-silica needle of which the tip (i.d. 10 microm, o.d. 20 microm) centered in a 254-microm-i.d. sapphire orifice. The nebulizer, equipped with a 3-cm(3) drain-free vaporization chamber, enabled a stable introduction into an ICP of aqueous mobile phases containing up to 95% acetonitrile at eluent flow rates between 50 and 450 nL min(-1). The low dead volume of the interface resulted in a peak width of 1.3 s (at half-height) and the entirely preserved chromatographic resolution. An example application of the coupling to the analysis of a tryptic digest of a SIP18 protein containing two to nine selenomethionine residues was described. The absolute detection limit was 25 fg (80Se), which allowed the detection of low-abundant selenopeptides at the femtomole level. In contrast to electrospray MS, the ICPMS detection in nanoHPLC is unaffected by the coeluting matrix and concomitant compounds and offers an elegant method for the detection and quantification of minor heteroelement-containing species prior to or in parallel with ESI MS analysis.     

Halogenated polyethylenes as electron-sensitive resists

Irradiation of a layer of halogenated polyethylene with an electron beam at 10-kV accelerating potential brings about crosslinking of brominated and chlorobrominated polyethylenes, but the chlorinated polyethylenes undergo either crosslinking or degradation, depending on the electron charge delivered. The limiting charge value which separates these two effects was found to be ca. 1 × 10^?3C/cm². The minimum useful dose was found to increase in the order brominated, chlorobrominated, chlorinated polyethylene.     

STRUCTURE and PROPERTIES of ALKANAL OXIMES as COPPER EZTRACTANTS

ABSTRACT

Composition, structure and interfacial activity of alkanal oximes and kinetics of copper extraction from chloride solutions are discussed. Semiempirical self-consistent field calculations are used to study the structure of alkanal oximes and their mono- and dihydrates. These calculations are in a qualitative agreement with the ratio of alkanal (Z)-and (E)-isomers, interfacial activity and kinetics data.     

Extracts of phenolic compounds from seeds of three wild grapevines-comparison of their antioxidant activities and the content of phenolic compounds

Phenolic compounds were extracted from three wild grapevine species: Vitis californica, V. riparia and V. amurensis seeds using 80% methanol or 80% acetone. The total content of phenolic compounds was determined utilizing the Folin-Ciocalteu’s phenol reagent while the content of tannins was assayed with the vanillin and BSA precipitation methods. Additionally, the DPPH free radical scavenging activity and the reduction power of the extracts were measured. The RP-HPLC method was applied to identify the phenolic compounds in the extracts, such as phenolic acids and catechins. The seeds contained large amounts of tannins, catechins and gallic acid and observable quantities of p-coumaric acid. The total content of phenolic compounds and tannins was similar in the extracts from V. californica and V. riparia seeds. However, the total content of total phenolic compounds and tannins in the extracts from V. californica and V. riperia seeds were about two-fold higher than that in the extracts from V. amurensis seeds. Extracts from seeds of the American species (V. californica and V. riparia) contained similarly high concentrations of tannins, whereas extracts from seeds of V. amurensis had approximately half that amount of these compounds. The content of catechin and epicatechin was similar in all extracts. The highest DPPH^• anti-radical scavenging activity was observed in the acetonic and methanolic extracts of V. californica and V. riparia seeds— while the acetonic extract from the V. californica seeds was the strongest reducing agent.     

Conductive composites of PVC and wood's metal with interpenetrating network structure

This work presents composite materials with interpenetrating network structure based on thermoplastic polymer and low melting metal alloy. Composites with various alloy content were prepared by PVC powder sintering to obtain polymer matrix with open pores. Then, liquid Wood's metal was intruded into the matrix using a pressure autoclave. Obtained composites have been studied with respect to microstructure, mechanical, thermal, and electrical properties. SEM micrographs revealed good dispersion of metal in the matrix but at low loading levels it is incomplete. Addition of metal improved mechanical properties, especially flexural strength. Electrical resistivity of samples varies from 10^?4 to 10^?5 Ω m and these values are typical of conductors. The measurements of electromagnetic interference shielding effectiveness (EMI SE) shows that generally PVC/Wood's metal composites have a good ability to shield electromagnetic waves. Composites containing more than 15 vol % Wood's metal exhibited EMI SE above 40 dB in the major part of frequency range. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The Effect of New Flame Retardant Systems Containing Montmorillonite-Butyl Acrylate Nanoclay on the Flammability Properties of Polyuerethane Polymer

The montmorillonite (MMT) was modified by butyl acrylate polymer. The newly modified MMT was characterized by TGA and DSC techniques. The modified MMT constitute melamine phosphate and different carbonizing agents and new flame retardant systems for poly urethane (PU) polymer. The flammability properties of the different PU formulations were characterized by cone calorimeter and ISO 1210 tests.The new flame retardant system gave the poly urethane polymer higher fire class, V0 (PU3 & 23). The thermal stability of the PU formulations was also improved.     

Antistatic and wetting properties of chemodegradable cationic surfactants containing 1,3-dioxolane moiety

In this paper we report some performance properties of [(2-alkyl-1,3-dioxolane-4-yl)methyl]trimethylammonium bromides (C _n -D-TAB, where C _n =n-C₉H₁₉, n-C₁₁H₂₃, n-C₁₃H₂₇), [(2,2-dialkyl-1,3-dioxolane-4-yl)methyl] dimethylammonium bromides (C _n C _m -D-TAB, where C _n =n-C₈H₁₇, n-C₁₀H₂₁ and C _m =CH₃ or C _n =C _m =n-C₆H₁₃), in relation to classical alkyltrimethylammonium bromides (C _n -TAB, where C _n =n-C₁₂H₂₅, n-C₁₄H₂₉ or C₁₆H₃₃) and dialkyldimethylammonium bromides (C _n C _m -DAB, where C _n =C _m =n-C₁₀H₂₁ and C₁₂H₂₅). Antistatic properties were measured by means of surface resistance (R _s), half charge decay time τ_1/2, and maximal voltage induced (U _ind) on polyethylene (PE) film and polypropylene (PP) nonwoven fabric. Wetting ability is reported as the concentration of surfactant necessary for immersion of a cottonfabric ring in 100 s, according to the Polish Standard PN-74/C-04800. All acetal-type surfactants showed the antistatic effect. The best results were given by C₉-D-TAB [R _s=8.5·10⁷ (PE), 1.1·10⁸ Ω (PP); τ_1/2=0.25 (PE), 0.30 s (PP); U _ind=205 (PE), 220 V (PP)] and C₁₁-D-TAB [R _s=8.7·10⁷ (PE), 1.3·10⁸ Ω (PP); τ_1/2=0.25 (PE), 0.30 s (PP); U _ind=190 (PE), 340 V (PP)] in relation to pure PE foils and PP fabric: R _s=3.0·10¹⁴ (PE), 9.8·10¹⁴ Ω (PP); τ_1/2=>600 (PE), >600 s (PP); U _ind=985 (PE), 940 V (PP). Both C₉-D-TAB and C₁₁-D-TAB indicate similar degrees of antistatic ability compared to C₁₀C₁₀-DAB. All C _n -TAB compounds do not show any antistatic effects. It was concluded that addition of the 1,3-dioxolane moiety to the hydrophobic tail of quaternary ammonium salts promotes both antistatic and wetting properties. Additionally, methyl or n-hexyl group incorporation at the C-2 carbon atom in the 1,3-dioxolane ring significantly decreases the surface conductivity.