Polymer–polymer interaction,in the presence of a solvent as measured by viscometry

Dilute solution viscometry experiments have been carried out in five ternary polymer systems solvent(1)/polymer(2)/polymer(3). Values of the specific viscosity of polymer (3) in a ‘binary solvent’ formed by polymer(2) + solvent(1) have been used to determine the compatibility of the polymer blends. Krigbaum and Wall formalism has been used to predict compatibility which relies on an interaction parameter that depends on the concentration, weight fraction and molar mass of each polymer. To reduce the dependences and to clarify the criterion of compatibility, a parameter independent of polymer (3) composition and molar mass has been deduced. This parameter shows the same behaviour with polymer(2) concentration as the Stockmayer–Fixman parameter B. © 2001 Society of Chemical Industry     

How do soil P tests,plant yield and P acquisition by <Emphasis Type="Italic">Lotus tenuis</Emphasis> plants reflect the availability of added P from different phosphate sources

The relative effectiveness (RE) of each one of three different sources of P—P in solution (Psol), triple superphosphate (TSP) and phosphate rock (PR)—for reflecting the availability of P in a P-deficient soil were assessed by measuring in Lotus tenuis variables associated with growth, organ morphology, and plant tissue P-content together with the amounts of P extracts from soil by two of the currently used soil-P tests—Bray I and Olsen. A hyperbolic equation was used to fit the response curves of each one of those plant variables to added-P. The ratio between the shapes of paired response curves of any P-sources was used to compute the RE and substitution rate (K) of one source relative to the other. More P was needed from TSP and PR compared to Psol-100% soluble P-source. On the average P applications as TSP relative to Psol and PR relative to TSP were only 68 and 63% effective respectively for plant growth. Plant roots were more sensitive than soil-P tests to detect shifts in P-availability from different P-sources. Because soil tests are commonly used to estimate the current P status in soil in order to calculate the optimum application levels of fertilizer P for a crop or pasture, these results would have practical agronomical consequences if reproduced in other cultivated species because they show that the response curve of a plant species as a function of added P and soil test might differ among fertilizer types, measured plant variables, and the test used to measure P availability in the soil.     

Intraspecific variations of Dekkera/Brettanomyces bruxellensis genome studied by capillary electrophoresis separation of the intron splice site profiles

In enology, "Brett" character refers to the wine spoilage caused by the yeast Dekkera/Brettanomyces bruxellensis and its production of volatile phenolic off-flavours. However, the spoilage potential of this yeast is strain-dependent. Therefore, a rapid and reliable recognition at the strain level is a key point to avoid serious economic losses. The present work provides an operative tool to assess the genetic intraspecific variation in this species through the use of introns as molecular targets. Firstly, the available partial D./B. bruxellensis genome sequence was investigated in order to build primers annealing to introns 5' splice site sequence (ISS). This analysis allowed the detection of a non-random vocabulary flanking the site and, exploiting this feature, the creation of specific probes for strain discrimination. Secondly, the separation of the intron splice site PCR fragments was obtained throughout the set up of a capillary electrophoresis protocol, giving a 94% repeatability threshold in our experimental conditions. The comparison of results obtained with ISS-PCR/CE versus the ones performed by mtDNA RFLP revealed that the former protocol is more discriminating and allowed a reliable identification at strain level. Actually sixty D./B. bruxellensis isolates were recognised as unique strains, showing a level of similarity below 79% and confirming the high genetic polymorphism existing within the species. Two main clusters were grouped at similarity levels of about 46% and 47%, respectively, showing a poor correlation with the geographic area of isolation. Moreover, from the evolutionary point of view, the proposed technique could determine the frequency of the genome rearrangements that can occur in D./B. bruxellesis populations.     

3D morphology of Au and Au@Ag nanobipyramids

The morphologies of Au and Au@Ag nanobipyramids were investigated using electron tomography. The 3D reconstruction reveals that the Au bipyramids have an irregular six-fold twinning structure with highly stepped dominant {151} facets. These short steps/edges stabilized via surface adsorbed CTAB favor the growth of silver on the lateral facets leading to strong blue shifts in longitudinal plasmon surface resonance.