Environmentally friendly vapour phase synthesis of alkylquinolines

2-methyl-8-ethylquinoline (MEQUI) was synthesized from ethylene glycol and an excess of 2-ethylaniline, operating in the vapour phase on K10 montmorillonite. Its structure was confirmed by ¹H-NMR (200 MHz) spectra recorded in CDCl₃ and DMSO. The synthesis of MEQUI is favoured by increasing the reaction temperature and amount of ethylene glycol, operating in a partially reducing atmosphere and feeding small amounts of water inside the organic feed. A possible reaction pathway proposed was confirmed by feeding a 2-ethylaniline/crotonaldehyde mixture. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fatty acid and oil diversity of cupheaviscosissima: A source of medium- chain fatty acids

Cuphea viscosissima Jacq. is being developed as a commercial source of caprylic, capric, lauric, and myristic acids. Germplasm resources for characterizing the genetic diversity of this species became available following explorations by the United States Department of Agriculture (USDA) in 1986 and 1987. In this paper, we describe the fatty acid and oil percentage diversity of forty- two populations ofC. viscosissima collected from seven states within the United States. Caprylic (18.0%) and capric acid (69.9%) were the major fatty acids of these populations. The fatty acid percentage ranges were narrow for every fatty acid,e.g., 16.4 to 20.4% for caprylic acid and 66.6 to 71.3% for capric acid. The maximum lauric acid percentage was 3.4%. Oil ranged from 27.3 to 33.4%. Although the populations surveyed cover a fairly wide geographic range, they display limited fatty acid diversity. Surveys of germplasm from other parts of the range are needed to further characterize the fatty acid diversity of this species. To whom correspondence should be addressed.     

Permeated Porous Silicon Suspended Membrane as Sub-ppm Benzene Sensor for Air Quality Monitoring

To realise advanced microsensors for a reliable monitoring of very low concentrations of pollutant species such as NO_x, SO₂, CO, O₃ and aromatic hydrocarbons, the use of porous silicon (PS) permeated with semiconducting oxides has been explored. To reduce the power consumption and to make feasible the device to operate in a fast pulsed temperature mode, a novel sensor architecture has been designed. The main feature of the device is represented by a permeated suspended macroporous Si membrane, few tens of microns thick. In this paper the porous silicon formation through a suspended silicon membrane and the morphological characterization of the PS layer are reported. Moreover, the performance of a C₆H₆ gas sensor based on the suspended macroporous Si membrane (30 m thick), permeated with the chemical precursor of Sn oxide is presented. The results have demonstrated the feasibility to realize a macroporous silicon suspended membrane with high specific surface area, efficient electrical insulation and negligible warpage. Furthermore, the permeation of the oxidized macroporous silicon membrane with SnO₂ has been proved to be a valuable approach to fabricate gas sensors suitable to detect aromatic hydrocarbons in a sub-ppm range.     

A re-appraisal of the nature of the atropine-resistant contraction to electrical field stimulation in the human isolated detrusor muscle

We investigated whether in human isolated detrusor strips the atropine-resistant contractile response to electrical field stimulation was mediated by ATP (or a related purine), as previously shown in the urinary bladder of other mammalian species. Electrical stimulation (1-50 Hz for 5 s at 1 min intervals, 0.1 ms pulse width, 60 V) elicited reproducible, frequency-dependent twitch contractions, which were markedly reduced by atropine (10 microM). Tetrodotoxin (TTX: 1 microM) inhibited contractile responses to a similar degree. When applied together, atropine and TTX caused an inhibition which was superimposable to that caused by either drug alone. The TTX-resistant contractions were totally unaffected by omega-conotoxin GVIA (omega-CTX: 0.1 microM). The atropine-resistant contractions were unaffected by the P2-purinoceptor antagonists suramin (300 microM) and PPADS (30 microM), at concentrations which virtually suppressed the contractile response induced by applied ATP (10 microM(-1) mM). As previously described, antagonism of the ATP-induced contractions by suramin (30, 100, 300 microM) and PPADS (3, 10, 30 microM) was insurmountable, with apparent 'pA2' values (calculated at the lowest antagonist concentrations) of 4.9 and 5.2, respectively. It is concluded that, under our experimental conditions, the non-cholinergic (atropine-resistant) component of the excitatory transmission in the human detrusor is not mediated by neural release of ATP, in spite of the presence of excitatory P2-purinoceptors on the effector cells. The TTX- and omega-CTX-resistant, non-cholinergic component might be related to the release of unknown transmitter(s) through a mechanism independent of both Na+- and N-type Ca2+-channels. More likely, the atropine-resistant component may reflect direct smooth muscle excitation since the human detrusor has a very short chronaxie (Sibley 1984).     

On the existence of maximum entropy distributions with four and more assigned moments

It is known that the probability distribution satisfy the Maximum Entropy Principle (MEP) if the available data consist in four moments of probability density function. Two problems are typically associated with use of MEP: the definition of the range of acceptable values for the moments M_i; the evaluation of the coefficients a_j. Both problems have already been accurately resolved by analytical procedures when the first two moments of the distribution are known.

In this work, the analytical solution in the case of four known moments is provided and a criterion for confronting the general case (whatever the number of known moments) is expounded. The first four moments are expressed in nondimensional form through the expectation and the coefficients of variation, skewness and kurtosis. The range of their acceptable values is obtained from the analytical properties of the differential equations which govern the problem and from the Schwarz inequality.     

A new ternary mixed oxide catalyst for ammoxidation of propane: Sn/V/Sb

The catalytic properties of a Sn/V/Sb mixed oxide for propane ammoxidation to acrylonitrile are studied in this paper. In particular the antimony and vanadium amounts were changed in order to optimize the relative atomic ratio. The ternary sample with the best catalytic performance was compared with the analogous binary samples (Sn/Sb and Sb/V). The results obtained indicate that vanadium is responsible for the paraffin activation, nevertheless much vanadium produces a lot of carbon oxides. Antimony is responsible for the insertion of nitrogen in the molecule (it can be considered as an acrylonitrile selectivity modulator); nevertheless, too much antimony deactivates the catalyst. Tin does not act only as a dispersive matrix for the active sites, but leads to the formation of a polyfunctional catalyst, increasing the rate of acrylonitrile formation from the intermediate propene. From a structural point of view, this catalytic system can be described as a homogeneous system, containing microfields of rutile type oxide (SnO₂), promoted with antimony and vanadium in substitutional solid solution, dispersed in an excess of amorphous antimony oxide. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spatial planning for wind farms: perspectives of a coastal area in southern Brazil

Clean Technologies and Environmental Policy - Wind energy is considered one of the most promising clean technologies for power generation. For the sustainable development of this industry, it is...