Measurement and estimation of aromatic plant dielectric properties. Application to low moisture rosemary

Essential oils are important in the flavour and cosmetic industries. Recently, microwave energy has been applied in different extraction processes to obtain essential oils with quality and yield similar to those obtained using steam distillation, but using less energy and time. The dielectric properties of any given material are of critical importance when seeking to understand its response to applied electromagnetic waves. Nevertheless, data related to aromatic plants are scarce. This paper addresses the measurement and estimation of dielectric properties of herbal matrices as a part of the study of the fundamental phenomenology behind the extraction of essential oils with microwaves. A cavity perturbation system was used to measure the properties of the plant matrix, and dielectric mixture equations were used later to try to reproduce the results obtained. The dielectric properties of partly dried rosemary, rosemary's essential oil and oven-dry plant material were measured at temperatures between 20 °C and 160 °C, and atmospheric pressure, at frequencies of 2450 MHz and 910 MHz. The results show a strong influence of water content on the dielectric properties. A new predictive approach that uses the results from measurements of dielectric properties from the different constituents to obtain effective mixture dielectric properties is proposed. The predicted values of the dielectric constants were better than those of the loss factors.     

The infrared spectrum of Al2H6 in solid hydrogen

Although many volatile binary boron hydride compounds are known, binary aluminum hydride chemistry is limited to the polymeric (AlH3)(n) solid. The reaction of laser-ablated aluminum atoms and pure H2 during codeposition at 3.5 kelvin, followed by ultraviolet irradiation and annealing to 6.5 kelvin, allows dimerization of the intermediate AlH3 photolysis product to form Al2H6. The Al2H6 molecule is identified by seven new infrared absorptions that are accurately predicted by quantum chemical calculations for dibridged Al2H6, a molecule that is isostructural with diborane.     

Alcohol oxidation in rate inhibited by pyrazole, oximes, and amides

Pyrazole, previously reported to inhibit ethanol oxidation in the rat, also effectively blocks the in vivo metabolism of methanol, propanol, isopropanol, n-butanol, and isobutanol. A variety of oximes and amides are also effective inhibitors of ethanol metabolism. These various inhibitors may prove important in the elucidation of several facets of alcohol metabolism and also may have application in the treatment of methanol poisoning and in the reduction of the sequelae of the disulfiram-ethanol reaction syndrome in man.     

Soil physical and chemical changes due to tillage and their implications for erosion and productivity

A seven-year tillage trial was conducted in central New South Wales, Australia to measure the effect and extent of conservation tillage practices on soil physical and chemical properties. Three tillage treatments, traditional tillage (TT), reduced tillage (RT) and direct drilling (DD) were imposed on hardsetting red-brown earths at Cowra and Grenfell. A fourth treatment, direct drilling without grazing (NT) was imposed at Cowra only.

At Cowra there was a significant trend of reduced total runoff in the DD and NT treatments but not in the RT treatment. Runoff significantly increased in the TT treatment.

At Grenfell, runoff decreased in all treatments but only significantly in the DD and RT treatments. Similar trends in total sediment loss were measured at both sites.

Associated physical measurements of saturated hydraulic conductivity, sorptivity and bulk density confirmed that the changes in runoff were due to the creation of macroporosity greater than 0.75 mm diameter. The relationship between macroporosity, organic carbon and aggregate stability is discussed. Conclusions were that in these soil types runoff and sediment loss were affected more by destruction of macroporosity due to cultivation than changes in organic carbon from residue retention. To achieve these soil improvements using conservation tillage a continuous cropping period of four years was necessary to obtain significant and consistent trends.

Soil chemical data showed that total nitrogen increased with conservation tillage practices. Available phosphorus changes due to tillage were not observed because of more than adequate fertiliser applied. Soil pH decreased significantly in the DD and NT treatments at Cowra only. The implications of these chemical changes are discussed.     

The influence of flow conditions on the removal of heavy metals in the primary sedimentation process

A pilot scale primary sedimentation pilot plant, treating raw sewage, was used to assess the efficiency of removal of Cd, Cr, Cu, Ni, Pb, and Zn. Heavy metal removals were determined during conditions designed to simulate normal dry weather flow, three times dry weather flow and diurnal variations in flow. During these experiments, the flow of sewage to the works where the pilot plant was sited also varied. It was found that short term variations in heavy metal concentrations in the raw sewage were related to the flow, although percentage removals appeared to be relatively unaffected by heavy metal concentrations. Removals during normal dry weather flow conditions were generally in the range of 25 to 50%, with Cu and Pb removals highest and Ni removal lowest. Lower removal efficiencies were observed when the flow to the pilot plant was increased three-fold, and the poorest removals were observed under variable flow conditions.     

The speciation of metals in sewage and activated sludge effluent

A gel filtration chromatography technique was used to separate soluble species of Cd, Cu, Co, Mn, Ni, and TI in the influent and effluent of a laboratory scale activated sludge simulation operated at a range of sludge ages from 3 to 18 days. It was found that, whilst there was no general trend for all six metals, Cd and Mn associated mainly with low molecular weight fractions; Co, Cu, and Ni with a range of predominantly high molecular weight fractions; and TI tended towards association with high molecular weight fractions which influenced metal solubility and appeared to be significant in determining metal removal. It appeared that all metals exhibited high affinity for mixed liquor suspended solids (MLSS) and that this affinity was strongest for Cu and Cd. Nickel, Co, Cu, and TI appeared to show a high affinity for polymeric microbial products produced at longer sludge ages. The gel filtration technique was found to be useful in the separation of metal species in conjunction with a sufficiently sensitive detector provided their concentrations in the original sample were relatively high.     

Isolation and identification of novel tocotrienols from rice bran with hypocholesterolemic, antioxidant, and antitumor properties

Two novel tocotrienols were isolated from stabilized and heated rice bran, apart from the known alpha-, beta-, gamma-, and delta-tocopherols and tocotrienols. These new tocotrienols were separated by HPLC, using a normal phase silica column. Their structures were determined by ultraviolet, infrared, nuclear magnetic resonance, circular dichroism, and high-resolution mass spectroscopies and established as desmethyl tocotrienol [3, 4-dihydro-2-methyl-2-(4,8,12-trimethyltrideca-3'(E),7'(E), 11'-trienyl)-2H-1-benzopyran-6-ol] and didesmethy tocotrienol [3, 4-dihydro-2-(4,8,12-trimethyltrideca-3'(E),7'(E), 11'-trienyl)-2H-1-benzopyran-6-ol]. These tocotrienols significantly lowered serum total and LDL cholesterol levels and inhibited HMG-CoA reductase activity in chickens. They had much greater in vitro antioxidant activities and greater suppression of B16 melanoma cell proliferation than alpha-tocopherol and known tocotrienols. Results indicated that the number and position of methyl substituents in tocotrienols affect their hypocholesterolemic, antioxidant, and antitumor properties.