Comparisons of water quality parameters from diverse catchments during dry periods and following rain events

In this study, 12 catchments sites located along the north coast of New South Wales in Australia were grouped into the four categories of septic, cattle, sewage treatment plant (STP) and forested sites via cluster analysis based on their land use patterns. Water samples from all these sites were collected between October 2004 and June 2006 at a regular monthly interval and within 48 h of rain events. The samples were analyzed for bacterial counts including faecal coliform and total coliform; faecal sterols including coprostanol, epicoprostanol, cholesterol, cholestanol, 24-ethylcoprostanol, campesterol, stigmasterol and beta-sitosterol; and the elements including Na, Rb, Sr, Ag, Cd, Sn, Cs, Ba, Hg, Tl, Pb, Bi, U, Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, K, As, Se, P and Mo. Over the course of the sampling period, the STP site had the highest average coprostanol level of 1693+/-567 ng/L which was significantly higher (p<0.05) than the septic sites (190+/-71 ng/L), the cattle sites (163+/-94 ng/L) and forested sites (14+/-4 ng/L). As expected, the forested sites had significantly lower average level of faecal coliforms (373+/-87 cfu/100 mL) compared with the STP (1395+/-574 cfu/100 mL), septic (1243+/-494 cfu/100 mL) and cattle sites (535+/-112 cfu/100 mL). The concentrations of coprostanol were not correlated with the numbers of faecal coliform bacteria when the entire data set was evaluated. The forested sites generally had the lowest average levels of elemental compositions, with significantly lower levels noted for Na, U, Mg, V, Cu, Sr, K, As, P and Mo, whereas Fe was the only element notably higher in the forested sites. Temporal and rain events analyses of the data set revealed that elevated levels of both coprostanol and faecal coliforms were not exclusive to rain events. The average coprostanol levels in rain event samples at each site were not significantly different compared with the corresponding dry event samples. Conversely, faecal coliform numbers increased by 2-4 times in rain events samples from septic, cattle and forested sites, but did not alter in the STP site. Multivariate analyses identified coprostanol and Sr as major contributing factors for the discrimination of septic, cattle, STP and forested sites for both rain and dry events samples. It was clear that each land use type of catchment could be characterized by biochemical, bacteriological and elemental parameters.     

Bacterial source tracking from diverse land use catchments by sterol ratios

Water samples from sites potentially impacted by septic tanks, cattle, sewage treatment plant (STP) and natural forests were collected at regular monthly intervals and within 48 h of rainfall events between October 2004 and June 2006. All samples (n=296) were analysed for faecal coliforms and faecal sterols including coprostanol, epicoprostanol, cholestanol, cholesterol and 24-ethylcoprostanol. Faecal sterol ratios were used to assign human and/or herbivore contamination sources and to estimate their percentage relative contributions in water samples. The catchments had significantly different profiles of designated contamination origins (p<0.05), which were consistent with land use patterns. The STP impacted site had the highest incidence of human contamination assignations and the highest mean levels of coprostanol, whilst the forested site had the highest incidence of uncontaminated samples and the lowest mean concentration of coprostanol. Coprostanol concentrations were not always correlated with faecal coliform counts.     

Highly conductive, melt processable polymer composites based on nickel and low melting eutectic metal

Highly conductive polymers are difficult to process utilizing standard polymer approaches. This report describes a polymer composite loaded with a eutectic metal that is molten during melt processing along with a more traditional Nickel particulate filler. Conductivities over 300 S/cm were achieved, and 60 vol% metals loading was processable with a single screw extruder. The addition of the Nickel particulate was critical for maintaining eutectic dispersion. We anticipate that this approach will facilitate the implementation of conductive polymers into a broader variety of practical applications, due to the enhanced compatibility with standard polymer processing techniques such as extrusion, melt mixing, and resin transfer-molding operations.     

Solvent swelling behavior of Permian-aged South African vitrinite-rich and inertinite-rich coals

Two South African coals similar in rank and age, but different in maceral composition, were studied using solvent swelling. Inertinite-rich Highveld coal (dominated by semifusinite) and vitrinite-rich Waterberg coal were evaluated for swelling extent and swelling rate using N-methylpyrrolidone (NMP) and CS₂/NMP. A stop-motion videography method was developed to study individual particle swelling behavior. This method allowed observation of overshoot and climbing-type swelling, as well as swelling kinetics. Single-particle swelling experiments showed that both coals exhibited overshoot-type and climbing-type swelling. The inertinite-rich coal swelled much faster (in both solvents) than the vitrinite-rich coal. The swelling in CS₂/NMP was faster for both coals. Kinetic parameters showed that solvent swelling was governed by relaxation (super-Case II relaxation) of the coal structure. X-ray computed tomography was conducted over a 50 h swelling period in NMP for single particles of each coal. Anisotropic swelling was observed in all the particles (swelling greater perpendicular to the bedding plane than parallel to it). The subtle changes in molecular structure, fine structural and physical differences resulted in significant differences in solvent swelling behavior.     

One‐Step Multipurpose Surface Functionalization by Adhesive Catecholamine

Surface modification is one of the most important techniques in modern science and engineering. The facile introduction of a wide variety of desired properties onto virtually any material surface is an ultimate goal in surface chemistry. To achieve this goal, the incorporation of structurally diverse molecules onto any material surface is an essential capability for ideal surface modification. Here, a general strategy for surface modification is presented in which many diverse surfaces can be functionalized by immobilizing a wide variety of molecules. This strategy functionalizes surfaces by a one‐step immersion of substrates in a one‐pot mixture of a molecule and a catecholamine surface modification agent. This one‐step procedure for surface modification represents a standard protocol to control interfacial properties.     

Multi-Hop Wireless Backhaul Networks above 10 GHz: Connectivity and Critical Density Evaluation

Microwave links are the obvious mobile backhauling solution for many mobile operators. Multi-hops are likely to be necessary in order to ensure connectivity for mobile backhaul solutions. The subject of the present paper is the evaluation of the connectivity of wireless multi-hop backhaul networks assuming high frequency transmissions among the relays. A novel analytical physical propagation and engineering model is presented for the calculation of the connectivity of wireless multi-hop networks that appropriate for operating frequencies above 10 GHz. Assuming equal power transmissions from every node and a random spatial node distribution following the homogeneous Poisson process, we calculate the node isolation probability. Furthermore, we calculate the minimum required node density in order to keep the backhaul network almost connected. The sensitivity of the isolation probability and of the minimum node density on frequency of operation, transmission power and climatic conditions is also investigated. Some useful conclusions are drawn.     

Improved Synthesis of Buprenorphine from Thebaine and/or Oripavine via Palladium‐Catalyzed N‐Demethylation/Acylation and/or Concomitant O‐Demethylation

An improved preparation of buprenorphine via palladium‐catalyzed N‐demethylation/acylation is reported. Three routes were investigated and compared in overall yield. The first involved N‐demethylation/acylation of an advanced intermediate obtained from thebaine followed by hydrolysis of the N‐acetamide and alkylation with cyclopropylmethyl bromide and/or reduction of the N‐acetyl group with the Schwartz reagent followed by N‐alkylation. The second route employed cyclopropylcarboxylic acid anhydride in the N‐demethylation/acylation protocol and subsequent reduction of the cyclopropylcarboxamide by either lithium aluminum hydride or under hydrosilylation conditions. Both of these routes originated in thebaine and therefore required O‐demethylation as a final step. The third route employed an N‐demethylation/acylation sequence starting from oripavine rather than thebaine, thus avoiding the O‐demethylation. The routes are compared for overall efficiency and experimental and spectral data are provided for all new compounds.     

Reducing the computational requirements of time‐reversal device optimizations

Time‐reversal simulations using conventional numerical algorithms provide the basis for a simple component optimization procedure. However, the computational requirements of the approach can become excessive, requiring the recording of the complete field time histories on a surface surrounding the problem space. In this work temporal, spatial and modal filtering methods are employed to significantly reduce the computational resources demanded by the time‐reversal process. The design of a number of WR90 (X‐band) waveguide components is used to quantify the balance between the computational efficiency gains and deterioration in the final design quality. Copyright © 2009 John Wiley & Sons, Ltd.     

Experimental and theoretical studies of thermal conductivity,viscosity and heat transfer coefficient of titania and alumina nanofluids

Thermal conductivity, viscosity and heat transfer coefficient of water-based alumina and titania nanofluids have been investigated. The thermal conductivity of alumina nanofluids follow the prediction of Maxwell model, whilst that of titania nanofluids is slightly lower than model prediction because of high concentration of stabilisers. None of investigated nanofluids show anomalously high thermal conductivity enhancement frequently reported in literature. The viscosity of alumina and titania nanofluids was higher than the prediction of Einstein–Batchelor model due to aggregation. Heat transfer coefficients measured in nanofluids flowing through the straight pipes are in a very good agreement with heat transfer coefficients predicted from classical correlation developed for simple fluids. Experimental heat transfer coefficients in both nanofluids as well as corresponding wall temperatures agree within ±10% with the values obtained from numerical simulations employing homogeneous flow model with effective thermo-physical properties of nanofluids. These results clearly shows that titania and alumina nano-fluids do not show unusual enhancement of thermal conductivity nor heat transfer coefficients in pipe flow frequently reported in literature.