Introduction In an earlier publication (2) a comparison was made of the growth regulating activites of various compounds as indicated by the elongation of sections of Avena coleoptiles. From this comparison it was seen that the substitution of various halogen atoms in the phenoxyacetic acid (POA) structure increased its effect on elongation except when both ortho positions were occupied. Also, ...

The effect of fluorine substitution on the hydrogen bond strength in alcohol-amine molecular complexes was investigated, with a combination of vapour phase infrared spectroscopy and theoretical calculations. The complexes were combined from methanol (MeOH), ethanol (EtOH) and trifluoroethanol (TFE) as the hydrogen bond donor, and either dimethylamine (DMA) or trimethylamine (TMA) as the accepto...

For many products the average price paid by consumers falls during periods of high demand. We use information from a large supermarket chain to decompose the decrease in the average price into a substitution effect, due to an increase in the share of cheaper products, and a price reduction effect. We find that for almost all the products we study the substitution effect explains a large part of...

Binding structures enrich traditional abstract syntax by providing support for representing binding mechanisms (based on deBruijn indices), term-schemata and a very clean algebraic theory of substitution. We provide a novel binding structure with the following main results: 1) The formalisation of a generic binding structure with the novel concept of effect-binding that enables the explicit rep...

Although there is no assumption of pore geometry in derivation of Gassmann’s equation, the pore geometry is in close relation with hygroscopic water content and pore fluid communication between the micropores and the macropores. The hygroscopic water content in common reservoir rocks is small, and its effect on elastic properties is ignored in the Gassmann theory. However, the volume of hygrosc...

Nowadays, ferroelectric thin films have attracted considerable attention because of their potential uses in device applications, such as sensors, micro electro-mechanical system (MEMS) and nonvolatile ferroelectric random access memory (NvFRAM) especially (Scott & Paz De Araujo, 1989; Paz De Araujo et al., 1995; Park et al. 1999). Lead zirconate titanate [PbZrxTi1-xO3 (PZT)] ferroelectric thin ...

The effect of thymine-5-bromouracil substitution on the regeneration and length of F pili produced by an F(+)Lac(+)/Lac(-)Thy(-) strain of Escherichia coli was studied by electron microscopy. When 5-bromouracil (5BU) incorporation into deoxyribonucleic acid (DNA) was maximal, the modal length of the pilus doubled and the number of pili per cell was approximately 50% that of thymine-grown cells....

BACKGROUND The nature of the heteroatom substitution in the nitrogen of a 3-aza-Cope system is explored. RESULTS While N-propargyl isoxazolin-5-ones suffer 3-aza-Cope rearrangements at 60°C, the corresponding N-propargyl pyrazol-5-ones need a higher temperature of 180°C for the equivalent reaction. When the propargyl group is substituted by an allyl group, the temperature of the rearrangement...

Thirty-one isomers of polychlorinated biphenyl (PCB) were examined for biodegradability by two species of Alcaligenes and Acinetobacter. The following relationships between chlorine substitution and biodegradability of PCBs were observed. (i) Degradation decreased as chlorine substitution increased. PCB isomers containing more than four chlorines were less susceptible to degradation. (ii) PCBs ...

In this communication we report the unexpected effect of ruthenium doping in sodium lightly doped manganites. This effect seems to be in contrast with the usual model applied to describe the effect of this magnetic ion into the manganite structure. We propose a possible compensation mechanism which seems also able to describe other peculiar features encountered in these materials.