Ageing of surface treated thermoplastic polyolefins

Thermoplastic polyolefin panels were treated with a flame, flame & water, and accelerated thermo molecular adhesion process (ATmaP) treatment. XPS, contact angle and adhesion test (pull off) results were acquired over a one year period to determine the changes in the elemental composition, surface energy and adhesion strength respectively over time. All surface-treated thermoplastic polyolefin samples showed a sharp decline in adhesion strength up to an ageing period totalling 6 months. The decline in adhesion strength was correlated with a decline in the nitrogen-containing constituents and C–O functional groups at the surface and a decline in surface energy for the flame & water-treated sample. There was no significant change in adhesion strength for all samples for ageing periods greater than 6 months. ATmaP-treated thermoplastic polyolefin outperformed the other two surface treatments in adhesion strength tests due to ATmaP retaining nitrogen-based functional groups (mainly nitrogen oxides) over the year long study. This retention of functionality allowed for a slower ageing process for ATmaP-treated surfaces in comparison to the other surface treatments.     

Electrochemical Properties and ESR Characterization of Mixed Valence alpha-[XMo(3)(-)(x)()V(x)()W(9)O(40)](n)()(-) Heteropolyanions with X = P(V) and Si(IV), x = 1, 2, or 3

Electrochemical behavior of the alpha-[SiMo(3)(-)(x)()V(x)()W(9)O(40)]((4+)(x)()())(-) and alpha-[PMo(3)(-)(x)()V(x)()W(9)O(40)]((3+)(x)()())(-) anions with x = 1, 2, or 3 were studied. Electrochemical reduction of each compounds was consistent with its Mo/V ratio, reduction of vanadium and molybdenum atoms occurring in the +0.6 to -0.6 V potential range. The one-electron-reduced species were prepared by electrolysis and then characterized by ESR spectroscopy. The g and A values for V(4+)ions appeared to depend on the nature of the surrounding atoms (Mo(VI), W(VI), and V(V)). In solution at 330 K, the ESR spectrum of the protonated alpha-H[SiMoV(IV)VW(9)O(40)](6)(-) anion displayed 29 superhyperfine lines which were related to the partial localization of the electron on one vanadium nucleus. The ESR spectra at room temperature for the divanadium-substituted anions showed a strong anisotropy of the A tensor which would be related to the electron transfer along a preferential axis. An isolated V(4+) signal was not observed, even at 12 K, indicating that the electron is never firmly trapped on one single vanadium atom.     

Surface molecular degradation of 3D glass polymer composite under low earth orbit simulated space environment

Epoxy resin reinforced with 3D parabeam glass fibre was subjected to low earth orbit (LEO) simulation conditions comprising ultra high vacuum, temperature cycling (TC), and ultraviolet (UV) radiation and atomic oxygen (AO) bombardment. Inspection of the same composite using only a selection of these hazardous conditions provided comparison measures to identify the effect of each condition on the surface degradation of the resin composite. Each of the individually selected conditions showed a different degradation mechanism that is accelerated by the presence of other conditions. X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and scanning electron microscopy (SEM) were used to provide surface information. The resin composite samples suffered surface oxidation that increased the oxygen content to 17.24% in comparison with the untreated sample (only 14.2%). The samples that were treated with AO showed higher C-O and CO functional groups on the surface in comparison with the rest of the samples (as indicated by XPS). Molecular information (from ToF-SIMS) showed that surface oxidation differs with different conditions and in comparison with the use of all conditions. All treated samples were shown to suffer significant chain scission and loss of volatiles as a result of the LEO conditions. The extent of the chain scission reaction for each condition can be indicated by the extent of the reduction of the relative concentration of the aliphatic hydrocarbon ions. The relative intensity of the C₄H₁₁N₄O₂⁺ ion showed that AO bombardment accelerated the oxidation of the surface. The AO effect is doubled when UV and TC are also present. SEM results indicated that sample surfaces were eroded and roughened upon exposure to LEO conditions. Presence of AO and UV in the LEO conditions introduced white deposits onto the surface, believed to be crosslinked formations.     

Evaluation of different machines used to quantify genetic modification by real-time PCR

Quantification of genetic modification (GM) is often undertaken to test for compliance with the European Union GM labeling threshold in food. Different control laboratories will often use common validated methods, but with different models of real-time PCR machines. We performed two separate ring trials to evaluate the relative precision and accuracy of different types of real-time PCR machines used to quantify the concentration of GM maize. Both trials used dual-labeled fluorogenic probes for quantification. The first ring trial used separate GM and reference assays (a single fluorescence channel), and the second used a combined duplex assay (two simultaneous fluorescence channels). Five manufacturers and seven models--including a 96-well microtiter-plate, rotary, and portable machines--were examined. In one trial, the machine used had a significant effect on precision, but in the other it did not. Overall, the degree of variation due to the machine model was lower than other factors. No significant repeatable difference in accuracy was observed between machine models. It was not possible to use sufficient replication of machine type in each laboratory to examine all sources of variation in this study, but the results strongly indicate that factors other than machine type or manufacturer (e.g., method or laboratory) contribute more to variation in a GM quantification result.     

Combinatorial approach to N-substituted aminocyclitol libraries by solution-phase parallel synthesis and preliminary evaluation as glucocerebrosidase inhibitors

Libraries of N-substituted aminocyclitol derivatives of the scyllo and racemic chiro series by means of parallel solution-phase methodology with the help of robotic technology are described. Chemical diversity has been introduced by reaction of selected scaffolds with a set of aldehydes, acyl chlorides, sulfonyl chlorides, chloroformates, and amines to afford the corresponding amines, amides, sulfonamides, carbamates and ureas, respectively. The optimized methodology has proven excellent, in terms of overall purities of the resulting libraries, for the production of amides. Sulfonamides and carbamates have been obtained in slightly lower purities, while amines afforded modest results. Selected library members have been evaluated as inhibitors of recombinant glucocerebrosidase with K(i) values ranging in the low micromolar scale for the most active members.     

Identification of a chemical indicator of the rupture of 1,4-β-glycosidic bonds of cellulose in an oil-impregnated insulating paper system

In this study, headspace gas chromatography/mass spectrometry has been used to assess the volatile by-products generated by the ageing of oil-impregnated paper insulation of power transformers. Sealed-glass ampoules were used to age under oxidative conditions 0.5-g specimens of insulating paper in 9 mL of inhibited mineral oil in a temperature range of 60–120 °C and moisture of 0.5, 1 and 2% (w/w). A linear relationship between one of the oil-soluble degradation by-products, i.e. methanol, and the number of ruptured 1,4-β-glycosidic bonds of cellulose, regardless of the type of paper (ordinary Kraft or thermally-upgraded (TU) Kraft paper), was established for the first time in this field. Ageing at 130 °C of model compounds of the Kraft paper constituents (α-cellulose, hemicellulose and lignin) and two cellulosic breakdown by-products (D-(+)-glucose and 1,6-anhydro-β-d-glucopyranose) confirmed that the α-cellulose degradation was mostly responsible for the presence of this molecule in the system. Furthermore, additional 130 °C-tests with six different papers and pressboard samples under a tight control of initial moisture indicated that at least one molecule of methanol is formed for each rupture of 1,4-β-glucosidic bond of the molecular chains. Stability tests showed that the ageing indicator is stable under the oxygen and temperature conditions of open-breathing transformers. The presence of methanol was detected in 94% of oil samples collected from over than 900 in-service pieces of equipment, confirming the potential for this application. Lastly, the tests have shown that oil-oxidation by-products and TU-nitrogenous agents modify the methanol partitioning coefficients in the paper/oil/air system, which makes their study essential over a range of field conditions encountered by power transformers. Results are presented and discussed in comparison with 2-furfuraldehyde, which is the current reference in the domain.     

Synthesis of l,l-puromycin

l,l-Puromycin, a diastereomer of the natural peptidyl nucleoside antibiotic puromycin, has been synthesized from l-xylose in 13 steps.     

Comparison of purge and trap GC/MS and spectrophotometry for monitoring petroleum hydrocarbon degradation in oilfield produced waters

Results of using a field spectrophotometer and its appropriate protocols as a surrogate method for an oilfield produced water treatment process is presented. Methylene chloride extractions of the produced water before and after treatment maintained a yellow color pigment that was directly proportional to the hydrocarbon concentration. From this, an absorption spectrum and standard curve were developed. A resultant linear plot of the standard curve indicated that there is an excellent correlation (r²=0.9847) between the varying concentrations and the associated absorbance values at a wavelength of 400 nm. Total n-alkane concentration comparisons between the laboratory GC/MS analysis and the spectrophotometry analysis generated data of similar accuracy and precision at concentrations ranging from 1 to 137 mg/l (alpha=0.05). Linear comparisons between GC/MS and spectrophotometric coefficients were near unity, with the constant being near zero, with a correlation coefficient (r²) of 0.99. Based on this study, spectrophotometry is a complimentary method to GC/MS for determining total n-alkane concentrations in oilfield produced water samples.