A unified formulation for continuum mechanics applied to fluid–structure interaction in flexible tubes

This paper outlines the development of a new procedure for analysing continuum mechanics problems with a particular focus on fluid–structure interaction in flexible tubes. A review of current methods of fluid–structure coupling highlights common limitations of high computational cost and solution instability. It is proposed that these limitations can be overcome by an alternative approach in which both fluid and solid components are solved within a single discretized continuum domain. A single system of momentum and continuity equations is therefore derived that governs both fluids and solids and which are solved with a single mesh using finite volume discretization schemes. The method is validated first by simulating dynamic oscillation of a clamped elastic beam. It is then applied to study the case of interest—wave propagation in highly flexible tubes—in which a predicted wave speed of 8.58 m/s falls within 2% of an approximate analytical solution. The method shows further good agreement with analytical solutions for tubes of increasing rigidity, covering a range of wave speeds from those found in arteries to that in the undisturbed fluid. Copyright © 2005 John Wiley & Sons, Ltd.     

Volatiles in home-brewed beers and wines

Home-brewed beers and wines from various sources have been analysed by gas-liquid chromatography. It was found that the amount of volatiles present especially the fusel oil fraction was invariably higher than in commercially brewed drinks. The consequences and possible dangers of this are discussed.     

PRELIMINARY INVESTIGATION OF THE ELECTROPHORETIC PROPERTIES OF CARAMELS

The movement of coloured components in various commercial caramels on horizontal paper electrophoresis was investigated. Buffers covering a wide range of pH values were used to show that no movement was exhibited by the coloured caramel components at their iso-electric points. These components are positively charged at pH values more alkaline than their iso-electric point and move towards the anode whereas at pH values more acid than their iso-electric point they are negatively charged and move towards the cathode. The results suggest that this technique may be of greater value than existing techniques for the accurate assessment of the iso-electric points of caramels.     

Transformation of Lowland Rainforest into Oil-palm Plantations and use of Fire alter Topsoil and Litter Silicon Pools and Fluxes

Silicon - The effects of land use and fire on ecosystem silicon (Si) cycling has been largely disregarded so far. We investigated the impacts of land use and fire on Si release from topsoils and...     

VOLATILE CONSTITUENTS OF VINEGAR. III. FORMATION AND ORIGIN OF VOLATILES IN LABORATORY ACETIFICATIONS

The volatiles produced during commercial malt vinegar manufacture have been examined using laboratory scale acetifications. The formation and changes of these volatiles in surface culture, aerated and submerged fermentations were found to be substantially similar to those found in the commercial process. Losses resulted with higher temperatures and submerged aeration. With maximum aeration the levels of propionic acid and acetoin decreased. The oxidations of n-propyl, isobutyl, sec-butyl, n-amyl and iso-amyl alcohols relative to ethanol have been compared to those found by Tanaka. The metabolic pathways which are probably responsible for the origin of these volatiles are discussed.     

AC-conductance and capacitance measurements for ethanol vapor detection using carbon nanotube-polyvinyl alcohol composite based devices

We report the preparation of inexpensive ethanol sensor devices using multiwalled carbon nanotube-polyvinyl alcohol composite films deposited onto interdigitated electrodes patterned on phenolite substrates. We investigate the frequency dependent response of the device conductance and capacitance showing that higher sensitivity is obtained at higher frequency if the conductance is used as sensing parameter. In the case of capacitance measurements, higher sensitivity is obtained at low frequency. Ethanol detection at a concentration of 300 ppm in air is demonstrated. More than 80% of the sensor conductance and capacitance variation response occurs in less than 20 s.     

Composites of polyvinyl alcohol and carbon (coils, undoped and nitrogen doped multiwalled carbon nanotubes) as ethanol, methanol and toluene vapor sensors

We investigate the chemical sensing behavior of composites prepared with polyvinyl alcohol and carbon materials (undoped multiwalled carbon nanotubes, nitrogen-doped multiwalled carbon nanotubes and carbon nanocoils). We determine the sensitivity of thin films of these composites for ethanol, methanol and toluene vapor, comparing their conductance and capacitance responses. The composite that exhibits highest sensitivity depends on specific vapor, vapor concentration and measured electrical response, showing that the interactivity of the carbon structure with chemical species depend on structural specificities of the carbon structure and doping.     

VOLATILE CONSTITUENTS OF VINEGAR. II. FORMATION OF VOLATILES IN A COMMERCIAL MALT VINEGAR PROCESS

Gas liquid chromatography was used to fractionate the alcohols, esters, carbonyls and acids formed in a commercial process of vinegar manufacture. Ethyl, n-propyl, sec-butyl, iso-butyl, n-amyl and iso-amyl alcohols, and iso-butyl, sec-butyl and n-amyl acetates were produced during the initial alcoholic fermentation. During acetification, propionic acid, iso-butyric acid and acetoin were produced. There was no increase in the number of volatiles or in their concentration during the maturing process of the charging wort or the subsequent treatments and storage period of the vinegar after acetification. A loss in the lower boiling point volatiles occurred during the storage of all the samples examined. An assessment has been made of the formation of these volatiles both before and after acetification.     

Treatment of rising damp and salt decay: the historic masonry buildings of Adelaide,South Australia

The City of Adelaide suffers from rapid damage to historic building materials due to salts, rising damp, and damp-proof course failures. Adelaide City Council has partially funded repairs to over 400 buildings in the past 15 years. To begin to examine the scope of this problem and the effectiveness of various treatments, 24 historic buildings in Adelaide were examined, with a focus on the building materials, historic interventions and current treatments applied to treat rising damp and salt decay. Analysis of 90 samples found high levels of sodium sulfate, sodium chloride and sodium nitrate in cellars, ground water and building materials, suggesting a clear example of rising damp. Samples of disintegrating masonry, depth profiles acquired by drilling, poultices and damp proof courses (DPC) were analyzed by Ion Chromatography (IC) and Environmental Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (ESEM/EDS). Mercury Intrusion Porosimetry (MIP) and capillarity test were carried out in the building materials and DPCs showing that porous materials with high porosity, small pores and low strength are more prone to salt weathering. The City of Adelaide is a natural laboratory for comparing and analyzing different treatments of salt-laden masonry, with hundreds of treated buildings of the same age, in the same environment, and with similar building materials.