bluuebunny/crossref_metadata_2025 huggingface dataset:
Density functional theory for inhomogeneous associating chain fluids
Authors: Bryk P. , Sokołowski S. , Pizio O.
Published: July 2006

We propose a nonlocal density functional theory for associating chain molecules. The chains are modeled as tangent spheres, which interact via Lennard-Jones (12,6) attractive interactions. A selected segment contains additional, short-ranged, highly directional interaction sites. The theory incorporates an accurate treatment of the chain molecules via the intramolecular potential formalism and should accurately describe systems with strongly varying external fields, e.g., attractive walls. Within our approach we investigate the structure of the liquid-vapor interface and capillary condensation of a simple model of associating chains with only one associating site placed on the first segment. In general, the properties of inhomogeneous associating chains depend on the association energy. Similar to the bulk systems we find the behavior of associating chains of a given length to be in between that for the nonassociating chains of the same length and that for the nonassociating chains twice as large.
High-density InGaN nanodots grown on pretreated GaN surfaces
Authors: Chen P. , Chua S. J. , Tan J. N.
Published: July 2006

High-density InGaN nanodots are successfully grown on pretreated GaN surfaces. The GaN surfaces were covered by SiO2 layers firstly, and then the SiO2 layers were removed before the growth of InGaN on the GaN. After this process, the growth of InGaN on the GaN surfaces changed to a three-dimensional mode. However, on the GaN surface without the SiO2 treatment, the growth of InGaN maintained a two-dimensional growth mode as usual. The InGaN nanodots are 26to68nm in diameter, 3.6–15nm in height, and up to 9×1010cm−2 in density, which can be controlled by growth duration and substrate temperature. Comparing with the InGaN thin film grown on untreated GaN surface with the same growth conditions, the InGaN nanodots showed stronger photoluminescence in longer wavelength range at room temperature. The formation mechanism of the nanodots is described based on the GaN surface states changed by SiO2 coverage. This approach enables fabrication of dense and controllable InGaN nanodots.
Relation between space charge limited current and power loss in open drift tubes
Authors: Biswas Debabrata , Kumar Raghwendra
Published: July 2006

Drift space is a region free from externally applied fields. It is an important part of several devices involving charged particle beams. The space charge effect imposes a limit on the current that can be transported through a drift tube. A reasonable estimate of the space charge limited (SCL) current density (JSCLc) in closed drift tubes can be obtained from electrostatic considerations, despite the fact that charge particle transport results in electromagnetic radiation. Here we deal with the situation where the drift tube is open to electromagnetic radiation, for instance, due to the presence of a dielectric window. In such cases, electromagnetic radiation leaks out of the window, which results in a decrease in the average kinetic energy of electrons. If the injected current density is much lower than JSCLc, power loss does not result in a change in the transmitted current. As the injected current density is increased, power loss increases and at a critical value lower than JSCLc, the reflection of electrons begins to occur. We also show that the lowering of the space charge limited current on account of power loss can be incorporated in the standard electrostatic picture by introducing an effective voltage for the collection plate.
Combinatorial-mold imprint lithography: A versatile technique for fabrication of three-dimensional polymer structures
Authors: Low Hong Yee , Zhao Wei , Dumond Jarrett
Published: July 2006

A two-step fabrication technique based on nanoimprint lithography is described for the fabrication of three-dimensional micro- and nanostructures. By combining simple two-dimensional geometries from two molds, complex and useful three-dimensional structures are obtained. The careful selection of mold geometries constitutes a simplified and efficient approach toward building up desirable three-dimensional structures without resorting to the use of a sacrificial process or components. Three-dimensional structures fabricated for a variety of specific applications are presented using both thermoplastic and cross-linked polymer materials.
Impact of 4H– and 6H–SiC(0001) nitridation on Ga wetting layer development and GaN growth by molecular beam epitaxy
Authors: Kim Tong-Ho , Choi Soojeong , Brown April S. , Losurdo Maria , Bruno Giovanni
Published: July 2006

GaN epitaxial layers have been grown by plasma-assisted molecular beam epitaxy on Si-face 4H– and 6H–SiC(0001)Si substrates. The impact of the SiC surface preparation and oxide removal achieved via a Ga flash-off process followed by nitridation on the structure and properties of GaN epitaxial layers is articulated. A correlation among the SiC surface nitridation conditions, the Ga wetting layer development, the nucleation layer, and GaN crystalline properties is revealed.
Enhanced proton beams from ultrathin targets driven by high contrast laser pulses
Authors: Neely D. , Foster P. , Robinson A. , Lindau F. , Lundh O. , Persson A. , Wahlström C.-G. , McKenna P.
Published: July 2006

The generation of proton beams from ultrathin targets, down to 20nm in thickness, driven with ultrahigh contrast laser pulses is explored. The conversion efficiency from laser energy into protons increases as the foil thickness is decreased, with good beam quality and high efficiencies of 1% being achieved, for protons with kinetic energy exceeding 0.9MeV, for 100nm thick aluminum foils at intensities of 1019W∕cm2 with 33fs, 0.3J pulses. To minimize amplified spontaneous emission (ASE) induced effects disrupting the acceleration mechanism, exceptional laser to ASE intensity contrasts of up to 1010 are achieved by introducing a plasma mirror to the high contrast 10Hz multiterawatt laser at the Lund Laser Centre. It is shown that for a given laser energy on target, regimes of higher laser-to-proton energy conversion efficiency can be accessed with increasing contrast. The increasing efficiency as the target thickness decreases is closely correlated to an increasing proton temperature.
Resonance enhancement in piezoresponse force microscopy: Mapping electromechanical activity, contact stiffness, and Q factor
Authors: Jesse Stephen , Mirman Boris , Kalinin Sergei V.
Published: July 2006

Piezoresponse force microscopy (PFM) and spectroscopy of domain structure and switching dynamics at small excitation voltages require resonance enhancement of the surface displacements. The contact stiffness depends strongly on local elastic properties and topography resulting in significant variations of the resonant frequency. Moreover, the resonant response is determined both by the Q factor and the electromechanical activity. Here we develop a resonance-enhanced PFM that allows mapping of the local electromechanical activity, contact stiffness, and loss factor, thus avoiding limitations inherent to conventional frequency tracking. We anticipate that this method will be instrumental in imaging weakly piezoelectric materials and probing inelastic phenomena in ferroelectrics.
Titania-nanotube-array-based photovoltaic cells
Authors: Wang H. , Yip C. T. , Cheung K. Y. , Djurišić A. B. , Xie M. H. , Leung Y. H. , Chan W. K.
Published: July 2006

Dye-sensitized solar cells based on perpendicular titania nanotube arrays were fabricated. Titania nanotube arrays were prepared by anodization of Ti foil. The cell performance as a function of nanotube length and anodization method was investigated. Short circuit current density and cell efficiency increased with the nanotube length. Device performance was also affected by anodization method, spacer layer thickness, and annealing conditions. With optimized device structure and titania annealing procedure, short circuit current density of 3.28mA∕cm2 could be achieved under AM 1.5 simulated solar irradiation.
Electron holography for improved measurement of microfields in nanoelectrode assemblies
Authors: Chou Li-Jen , Chang Mu-Tung , Chueh Yu-Lun , Kim Joong Jung , Park Hyun Soon , Shindo Daisuke
Published: July 2006

An approach to investigate the electric field distribution and field-emission property of a single crystal tungsten oxide (WO3) nanowire by electron holography technique is presented, which solves the problems encountered in the traditional reconstruction of the holograms, the so-called perturbed reference wave. We proposed this unique method to meticulously illustrate the status of the surroundings of a single crystal nanowire under biased conditions. This paves the way to precisely quantifying the electric and magnetic field distributions for nanostructures as well as nanodevices.
Comparative Analysis of Soluble Phosphate Amendments for the Remediation of Heavy Metal Contaminants: Effect on Sediment Hydraulic Conductivity
Authors: Wellman Dawn M. , Icenhower Jonathan P. , Owen Antoinette T.
Published: July 2006

Environmental Context. The contamination of surface and subsurface geologic media by heavy metals and radionuclides is a significant problem within the United States Department of Energy complex as a result of past nuclear operations. Water-soluble phosphate compounds provide a means to inject phosphorus into subsurface contaminant plumes, to precipitate metal ions from solution. However, phosphate phases can form within the sedimentary pore structure to block a fraction of the pore space and inhibit further remediation of the contaminant plume. A series of tests have been conducted to evaluate changes in sedimentary pore structure during the application of several proposed phosphate remediation amendments. Abstract. A series of conventional, saturated column experiments have been conducted to evaluate the effect of utilizing in situ, soluble, phosphate amendments for subsurface metal remediation on sediment hydraulic conductivity. Experiments have been conducted under mildly alkaline and calcareous conditions representative of conditions commonly encountered at sites across the arid western United States, which have been used in weapons and fuel production and display significant subsurface contamination. Results indicate that the displacement of a single pore volume of either sodium monophosphate or phytic acid amendments causes approximately a 30% decrease in the hydraulic conductivity of the sediment. Long-chain polyphosphate amendments afford no measurable reduction in hydraulic conductivity. These results demonstrate (1) the efficacy of long-chain polyphosphate amendments for subsurface metal sequestration; and (2) the necessity of conducting dynamic experiments to evaluate the effects of subsurface remediation.
Characteristics of the Acidity in Acid Sulfate Soil Drainage Waters, McLeods Creek, Northeastern NSW, Australia
Authors: Green Rosalind , Waite T. David , Melville Michael D. , Macdonald Ben C. T.
Published: July 2006

Environmental Context. Acid sulfate soils are found in many low-lying coastal areas, but they can also be encountered in inland areas of Australia and other parts of the world. These soils typically contain iron sulfides, primarily pyrite (FeS2) and mackinawite (FeS), and the products that result from oxidation of these iron minerals. Acidic and metal-rich waters can be produced when the pyrite in soil is oxidized by natural means or accelerated when the soil is drained, which typically occurs when it is developed for agriculture or urban use. In general, acid sulfate soils become a problem when oxidation products are transported from the soil profile into nearby streams and estuaries, which can severely affect the ecology, biodiversity, economic development, and the aesthetics of adjacent waterways. The key contributors to acidity in drainage waters from the site examined are Al3+, AlSO4– and, under particular circumstances, Mn2+ and Fe2+, but the principal species contributing to acidity are strongly time variant and would be expected to vary from site to site.
Abstract. Catchments that contain acid sulfate soils can discharge large quantities of acid and dissolved metals into waterways. At McLeods Creek in far northern NSW, Australia, the acidity from the hydrolysis of dissolved metal species, particularly aluminium and iron, contributes to greater than 70% of the total acidity. Therefore, a poor relationship exists between both calculated and titrated acidity and pH because of the dominant influence of these hydrolyzable metal species. Determination of the so-called ‘cold acidity’ by direct titration with NaOH yields results that are difficult to replicate because of the buffering effects of suspended solids, carbon dioxide ingassing, and/or MnII and FeII oxidation in the sample as the titration end-point is approached. Samples that are pre-treated with sulfuric acid and hydrogen peroxide produce results (of ‘hot acidity’) that can be easily replicated and are similar to calculated acidities based on elemental analysis and speciation calculations. The cold acidity values for titrations of 105 water samples from the chosen field site are often higher than hot acidity values as a result of the loss of carbonate acidity during pre-treatment of samples for hot acidity analysis.
Bioaccessibility of Arsenic Bound to Corundum Using a Simulated Gastrointestinal System
Authors: Beak Douglas G. , Basta Nicholas T. , Scheckel Kirk G. , Traina Samuel J.
Published: July 2006

Environmental Context. Ingestion of soil contaminated with arsenic is an important pathway for human exposure to arsenic. The risk posed by ingestion of arsenic-contaminated soil depends on how much arsenic is dissolved in the gastrointestinal tract. Aluminum oxides are common components in the soil and act as a sink for arsenic. Knowledge of the behavior of arsenic associated with aluminum oxide surfaces in a simulated gastrointestinal tract will provide an understanding of the ingestion risk of arsenic-contaminated soil to humans.
Abstract. Arsenate adsorbed to oxide surfaces may influence the risk posed by incidental ingestion of arsenic-contaminated soil. Arsenate sorbed to corundum (α-Al2O3), a model Al oxide, was used to simulate ingested soil that has AsV sorbed to Al oxides. An in vitro assay was used to simulate the gastrointestinal tract and ascertain the bioaccessibility of arsenate bound to corundum. The surface speciation of arsenate was determined using extended X-ray absorption fine structure and X-ray absorption near edge structure spectroscopy. The arsenate sorption maximum was found to be 470 mg kg–1 and the surface speciation of the sorbed arsenate was inner-sphere binuclear bidenate. The AsV was found to only be bioaccessible during the gastric phase of the in vitro assay. When the sorbed AsV was <470 mg kg–1 (i.e., the sorption maxima) the bioaccessible As was below detection levels, but when sorbed AsV was ≥470 mg kg–1 the bioaccessible As ranged from 9 to 16%. These results demonstrate that the bioaccessibility of arsenate is related to the concentration and the arsenate binding capacity of the binding soil.
Corrigendum to: Determination of Selective Quinones and Quinoid Radicals in Airborne Particulate Matter and Vehicular Exhaust Particles
Authors: Valavanidis Athanasios , Fiotakis Konstantinos , Vlahogianni Thomais , Papadimitriou Vasilios , Pantikaki Vayia
Published: July 2006

Environmental Context.�Fine and coarse airborne particulate matter (PM) has been linked to increases in respiratory diseases and lung cancer. PM contains a variety of compounds, such as metals, polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, and quinones adsorbed in a carbonaceous polymeric matrix. Although quinones are found in small amounts in PM, they are capable of redox cycling and in the presence of oxygen catalyse the generation of reactive oxygen species (ROS) in biological systems. ROS are responsible for the induction of oxidative stress, especially oxidative damage to cellular proteins and DNA. This paper investigated quantitatively selected quinones and hydroquinones by high performance liquid chromatography in various airborne PM samples. Also, we investigated the presence of persistent semiquinone radicals in solid samples and quinoid radicals in aqueous extracts of alkaline solution by electron paramagnetic resonance spectroscopy.
Abstract.�In recent years, there has been an increasing interest in the study of the health effects of respirable particulate matter (PM) because of its deposition in the human lungs and adverse health effects. Analysis of PM content focused on substances of toxicological importance, such as polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, aliphatic hydrocarbons, alkyl-substituted benzenes and naphthalenes, transition metals and various quinones. Recent studies shifted their attention to quinones and their toxicological role in PM. Quinones can be transformed into their semiquinones, which undergo redox cycling and reduce oxygen to produce reactive oxygen species (ROS) in biological systems, resulting in the induction of oxidative stress, especially oxidative damage to cellular components and DNA. In the present study, the presence of five quinones, 1,2-benzenediol (catechol) and 1,4-benzenediol (hydroquinone) in various PM samples was identified and measured quantitatively by high performance liquid chromatography. Mean concentrations of individual target quinones ranged from 15-140 ng mg-1 in diesel and gasoline exhaust particles to 1.5-60 ng mg-1 (or 150-1100 pg m-3) in airborne PM (total suspended particulates, PM aerodynamic diameter 10 μm, PM aerodynamic diameter 2.1 μm) samples. Precision (repeatability and reproducibility) varied from 5 to 15%. Also, examples of electron paramagnetic resonance spectra for the single broad unstructured signal are presented, corresponding to the persistent stable semiquinone radicals of solid samples of PM, and the formation of quinoid radicals in aqueous extracts of PM samples in air-saturated carbonate-buffered solution, pH 9.5-10.
Novel Mild Hydrodechlorination of PCDDs, PCDFs, and co-PCBs inside Fly Ash Using a Calcium-Promoted Rhodium Carbon Catalyst in Methanol
Authors: Mitoma Yoshiharu , Takase Maki , Yoshino Yoshiko , Masuda Taizo , Tashiro Hideki , Egashira Naoyoshi , Oki Takashi
Published: July 2006

Environmental Context. The generic term ‘dioxins’, the family of which includes polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like compounds such as coplanar polychlorinated biphenyls (co-PCBs), is used to describe highly toxic and mutagenic compounds. Many methods that involve high-temperature or high-pressure dry hydrogen conditions to ensure adequate decomposition for persistent chlorinated aromatic pollutants present disadvantages for repeated synthesis or recovery of vaporized dioxins and co-PCBs. We discovered that highly efficient degradation of dioxins in fly ash is accomplished in 24 h using metallic calcium and Rh/C in alcohol in a sealed tube at 25°C at 0.15 MPa.
Abstract. Effective hydrodechlorination of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like compounds such as coplanar polychlorinated biphenyls in fly ash was achieved in 24 h using a simple stirring operation in a sealed tube with metallic calcium and Rh/C catalyst in an alcohol solution at room temperature with 0.15 MPa of increasing internal pressure. The initial 7806 pg dioxin toxic equivalent (TEQ) (g of ash)–1 of dioxins in fly ash, which had adsorbed inside the solid phase, was finally degraded to 23.6 pg of TEQ (g of ash)–1, according to estimation using gas chromatography–mass spectrometry analysis.
Colloidal Metals in the Tamar Estuary and their Influence on Metal Fractionation by Membrane Filtration
Authors: Howell Kate A. , Achterberg Eric P. , Tappin Alan D. , Worsfold Paul J.
Published: July 2006

Environmental Context. Trace metals play an essential role in the growth and function of aquatic organisms; however, enhanced metal concentrations can have detrimental effects on ecosystems. The distribution of metals between filterable and filter-retained phases is key to their bioavailability and biogeochemical cycling. Studies on rivers have shown that separating dissolved metals from particle-associated metals may introduce significant artefacts in the resulting filtrate concentrations. Comparable studies on turbid estuarine waters are necessary to improve the design of water sampling programmes.
Abstract. Total filterable and colloidal metals were measured in the Tamar Estuary. The colloidal fraction (Mc) was highly variable for each metal, both spatially and temporally. In April 2001, Alc and Coc were higher in the river than the estuary, Cdc, Crc and Pbc were lower, and Mnc and Uc were similar. In September 2001, Cdc was higher in the river than the estuary. Colloidal Al and Mn were positively correlated with concentrations of suspended particles, whereas the colloid contents of the other metals were primarily determined by additional factors. The effect of the colloidal metal content on resultant metal filtrate concentrations, as a function of sample volume filtered, was examined. The amount of Al, Cd, Cu, Pb, and U in the filtrate decreased significantly in at least one case, whereas Mn initially increased in some cases. There was no change for Co, Cr, and Zn. The implications of these results for the study of trace metals in moderately turbid estuaries are discussed.
Protective Role of Alginic Acid Against Metal Uptake by American Oyster (Crassostrea virginica)
Authors: Haye Jennifer M. , Santschi Peter H. , Roberts Kimberly A. , Ray Sammy
Published: July 2006

Environmental Context. Trace metals are both micronutrients and toxicants, depending on concentration, and in coastal waters they bind to natural organic matter including nanoparticles. The binding type affects trace metal bioavailability to bivalves such as oysters, which ingest metals through water and food particles. Bivalves are biomonitors because of the high trace metal concentrations, especially Cu and Zn, in their tissues. Here, the polysaccharide alginic acid is shown to protect against the assimilation and bioavailability of trace metals to American oysters.
Abstract. Little is known about how colloidal macromolecular organic matter (COM) modifies the bioavailability of toxic metals to aquatic organisms. In order to understand the physical and chemical properties of COM on the bioavailability of some metals to estuarine bivalves used as biomonitors, American oysters (Crassostrea virginica) were exposed to natural COMs and model acid polysaccharides (APS, alginic acid (AA), kappa carrageenan (CAR), and latex particles), and natural colloidal organic carbon (COC), tagged with either radioactive Ag, Cd, Co, Cr, Fe, Hg or Zn, or 14C-labelled sugar OH groups. Filter-feeding oysters efficiently removed latex particles 0.04 µm in diameter, with removal half-times of 2.5–5.5 h, equivalent to a filtration rate of approximately 3 L day–1 g–1. Thus, AA protects against metal uptake by oysters, which is confirmed by metal dry-weight concentration factors (DCFs) similar to, or lower than, those for 14C-labelled AA. However, metal-DCFs for CAR and COC were higher than for 14C-labelled counterparts, suggesting that in these treatments, metal uptake was enhanced over that of carbon. The 14C-labelled AA was taken up significantly more than other 14C-labelled organics, suggesting different behavior in the digestive tract. Bioavailabilty of metals bound to organic nanoparticles with different nutritional and physiological properties is not fully understood, and will require further experiments.
Asymmetrical Flow Field Flow Fractionation - Multidetection System as a Tool for Studying Metal - Alginate Interactions
Authors: Alasonati Enrica , Stolpe Björn , Benincasa Maria-Anna , Hassellöv Martin , Slaveykova Vera I.
Published: July 2006

Environmental Context. Acidic polysaccharides are important components of the organic matter in ecosystems that are involved in the transport of metal pollutants. They are able to affect trace element cycling, both due to their metal binding properties and to their effect on aggregation and sedimentation of organic matter. In order to obtain more information regarding their role as metal pollutant carriers, the size distributions of alginate and metal alginate complexes have therefore been studied with novel instrumentation.
Abstract. The present study explores the potential use of asymmetrical flow field flow fractionation (aFlFFF) with a multidetection system for the study of metal–alginate interactions. aFlFFF, coupled on-line to a differential refractive index and seven angle laser light scattering detectors was used to provide information on the alginate size distributions. In parallel, the metal distributions of metal–alginate complexes were probed by aFlFFF–high resolution inductively coupled plasma-mass spectrometry. Average values and continuous distributions of molar masses, radiuses of gyration and hydrodynamic radiuses, which are critical for understanding the role of alginates as carriers of metal pollutants, were evaluated in presence of Pb or Cd and compared with those in metal-free solutions of alginate. The values of number average and weight average molar mass, weight average radius of gyration and shape factor for alginate were 150 and 188 kg mol–1, 53 nm and 1.7, respectively. Alginate molar mass and radius of gyration distributions were slightly shifted to higher values by the addition of micromolar concentrations of Pb or Cd. The alginate size distribution in the presence of Cd was similar to the alginate-alone control, whereas in the presence of Pb the size distribution was broader with a shift of the maximum toward higher molar masses.
Aquatic Colloids and Nanoparticles: Current Knowledge and Future Trends
Authors: Lead Jamie R. , Wilkinson Kevin J.
Published: July 2006

Environmental Context. The fate and behaviour of trace pollutants are very strongly modified, and usually dominated, by their physical and chemical interactions with naturally occurring aquatic colloids (defined as solid phase material with one dimension between 1 nm and 1 μm). This review summarises the area and key advances in the field of natural aquatic colloids, including technique development and quantification of colloidal structure and interactions with pollutants. The review also discusses areas in which significant advances are likely to be made or are needed and, as such, provides a framework for further work in the next few years. Abstract. Natural aquatic colloids are materials with one dimension between 1 nm and 1 μm. More informally defined, nanoparticles are materials with at least one dimension less than 100 nm. Both colloids and nanoparticles have significant effects on pollutant, nutrient, and pathogen chemistry, transport and bioavailability, and may themselves be bioavailable. Techniques for their fractionation, characterization and analysis have improved greatly in recent years. Although knowledge of their structure and environmental impact has also increased, it has not done so to the same degree and thus the field awaits the substantial application of new methodologies. This paper reviews the current state of the art in this area and also discusses likely future developments.
The Influence of Sample Preparation on Observed Particle Size Distributions for Contrasting Soil Suspensions using Flow Field-Flow Fractionation
Authors: Gimbert Laura J. , Haygarth Philip M. , Beckett Ronald , Worsfold Paul J.
Published: July 2006

Environmental Context. Colloids are an important environmental means for contaminant transport from land to water. Within the agricultural landscape, the mobilization of phosphorus species by soil leachate and drainage waters is a particularly important example. Colloidal material is, however, difficult to isolate and characterize, due in part to the dynamic nature of environmental systems and colloidal structure and in part of the lack of suitable analytical techniques. Field-flow fractionation is one emerging tool for the investigation of colloidal fractions in environmental matrices and for assessing how soil processes impact on water quality. Abstract. This paper reports the use of flow field-flow fractionation (FlFFF) as a suitable technique to characterize particle size distributions (PSDs) in the <1-μm fraction of ‘colloidal’ soil suspensions prepared from two contrasting soil types (one mineral rich and one organic rich). Both soils have been fully characterized and the <1-μm fraction obtained by gravitational settling of 1% w/v soil suspensions. The effect of shaking and settling times on observed PSDs was systematically investigated and revealed that gentle shaking for 16 h followed by gravity settling for 1 h gave reproducible results. Settling for longer periods resulted in re-aggregation of smaller particles and a shift in the PSDs to larger mean particle diameters. Changes in soil suspension concentration (0.25–1% w/v) had no significant effect on PSDs. Further fractionation of the gravitationally settled <1-μm fraction by centrifugation and filtration (to < 0.45 and < 0.2 μm) clearly showed that a significant component in each fraction was removed by the filtration process. This was true for both soil types and confirms that membrane filtration seriously underestimates the colloidal fraction in aquatic samples. These findings highlight the need for standardized and well-documented protocols for processing soil suspensions.
Human lactoferrin transgenic rabbits produced efficiently using dimethylsulfoxide - sperm-mediated gene transfer
Authors: Li Lan , Shen Wei , Min Lingjiang , Dong Huansheng , Sun Yujiang , Pan Qingjie
Published: July 2006

Transgenic animal mammary gland bioreactors are used to produce recombinant proteins. However, it is difficult to validate whether these transgenic domestic animals are able to express the recombinant protein efficiently in their mammary glands before the birth of transgenic offspring. In the present study, a simple and efficient method was established to evaluate the functionality of animal mammary gland tissue-expressed cassettes. The gene transfer vector pGBC2LF was constructed, and the expression of human lactoferrin (LF) gene was controlled by the goat β-casein gene 5′ flanking sequence. To obtain the most efficient transfection, the influence of DNA concentration, dimethylsulfoxide (DMSO) concentration, and the ratio of linear-to-circular DNA required for associating DNA with spermatozoa were evaluated. Transfection of exogenous DNA into rabbit spermatozoa was found to be efficient using 30 μg mL–1 DNA, DMSO at a final concentration of 3%, and a 3 : 1 ratio of linear-to-circular DNA, with 29 of 85 (34.1%) in vitro-fertilised embryos being transgenic. Using DMSO–sperm-mediated gene transfer (DMSO-SMGT), 89 rabbit offspring were produced, with 46 of these (57.1%) being transgenic. As mammary gland bioreactor models, 17 of 21 (81%) transgenic female rabbits could express human LF protein in their glands. During lactation of the transgenic rabbits, the highest level of human LF protein expressed was 153 ± 31 μg mL–1, and the mean expression level in all of the transgenic rabbits was 103 ± 20 μg mL–1 in the third week, declining gradually after this time. Our results demonstrate that transgenic rabbits produced by DMSO–SMGT were able to express human LF protein in the correct tissue.
Growth and histology of ovarian follicles after cold storage in the tammar wallaby
Authors: Richings Nadine M. , Shaw Geoffrey , Temple-Smith Peter D. , Renfree Marilyn B.
Published: July 2006

Cold storage is a simple method for storing and transporting tissues and organs. The reliability of this method for maintaining structure and function of marsupial ovarian tissue was assessed using histological techniques and follicle culture. Tammar wallaby ovaries were placed in cold storage (phosphate-buffered saline at 4°C) for 24 or 48 h. Although necrotic changes were evident in the germinal epithelium, cortex and interstitial tissue after cold storage, there was little evidence of necrotic changes in ovarian follicles and oocytes appeared normal. Secondary follicles isolated from ovarian tissue after cold storage grew by a similar amount to non-stored follicles when cultured for 4 days in vitro, but no follicles from any group developed to tertiary follicles. Cold storage for up to 24 h had little obvious effect on the structure of ovarian tissue and follicles isolated from this tissue maintained their structure during culture. However, degeneration in culture increased with storage time and was significantly higher after cold storage for 48 h. As demonstrated in the tammar wallaby, cold storage has potential as a method for storage and transport of marsupial ovaries up to 24 h.
Alzheimer's disease β-amyloid peptides are released in association with exosomes
Authors: Rajendran Lawrence , Honsho Masanori , Zahn Tobias R. , Keller Patrick , Geiger Kathrin D. , Verkade Paul , Simons Kai
Published: July 2006

Although the exact etiology of Alzheimer's disease (AD) is a topic of debate, the consensus is that the accumulation of β-amyloid (Aβ) peptides in the senile plaques is one of the hallmarks of the progression of the disease. The Aβ peptide is formed by the amyloidogenic cleavage of the amyloid precursor protein (APP) by β- and γ-secretases. The endocytic system has been implicated in the cleavages leading to the formation of Aβ. However, the identity of the intracellular compartment where the amyloidogenic secretases cleave and the mechanism by which the intracellularly generated Aβ is released into the extracellular milieu are not clear. Here, we show that β-cleavage occurs in early endosomes followed by routing of Aβ to multivesicular bodies (MVBs) in HeLa and N2a cells. Subsequently, a minute fraction of Aβ peptides can be secreted from the cells in association with exosomes, intraluminal vesicles of MVBs that are released into the extracellular space as a result of fusion of MVBs with the plasma membrane. Exosomal proteins were found to accumulate in the plaques of AD patient brains, suggesting a role in the pathogenesis of AD.
Structure of UDP-N-acetylglucosamine acyltransferase with a bound antibacterial pentadecapeptide
Authors: Williams Allison H. , Immormino Robert M. , Gewirth Daniel T. , Raetz Christian R. H.
Published: July 2006

UDP-GlcNAc acyltransferase (LpxA) catalyzes the first step of lipid A biosynthesis, the transfer of theR-3-hydroxyacyl chain fromR-3-hydroxyacyl acyl carrier protein (ACP) to the glucosamine 3-OH group of UDP-GlcNAc. LpxA is essential for the growth ofEscherichia coliand related Gram-negative bacteria. The crystal structure of theE. coliLpxA homotrimer, determined previously at 2.6 Å in the absence of substrates or inhibitors, revealed that LpxA contains an unusual, left-handed parallel β-helix fold. We now present the crystal structure at 1.8 Å resolution ofE. coliLpxA in a complex with a pentadecapeptide, peptide 920. Three peptides, each of which adopts a β-hairpin conformation, are bound per LpxA trimer. The peptides are located at the interfaces of adjacent subunits in the vicinity of the three active sites. Each peptide interacts with residues from both adjacent subunits. Peptide 920 is a potent inhibitor ofE. coliLpxA (Ki= 50 nM). It is competitive with respect to acyl-ACP but not UDP-GlcNAc. The compact β-turn structure of peptide 920 bound to LpxA may open previously uncharacterized approaches to the rational design of LpxA inhibitors with antibiotic activity.
Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels
Authors: Hill Jason , Nelson Erik , Tilman David , Polasky Stephen , Tiffany Douglas
Published: July 2006

Negative environmental consequences of fossil fuels and concerns about petroleum supplies have spurred the search for renewable transportation biofuels. To be a viable alternative, a biofuel should provide a net energy gain, have environmental benefits, be economically competitive, and be producible in large quantities without reducing food supplies. We use these criteria to evaluate, through life-cycle accounting, ethanol from corn grain and biodiesel from soybeans. Ethanol yields 25% more energy than the energy invested in its production, whereas biodiesel yields 93% more. Compared with ethanol, biodiesel releases just 1.0%, 8.3%, and 13% of the agricultural nitrogen, phosphorus, and pesticide pollutants, respectively, per net energy gain. Relative to the fossil fuels they displace, greenhouse gas emissions are reduced 12% by the production and combustion of ethanol and 41% by biodiesel. Biodiesel also releases less air pollutants per net energy gain than ethanol. These advantages of biodiesel over ethanol come from lower agricultural inputs and more efficient conversion of feedstocks to fuel. Neither biofuel can replace much petroleum without impacting food supplies. Even dedicating all U.S. corn and soybean production to biofuels would meet only 12% of gasoline demand and 6% of diesel demand. Until recent increases in petroleum prices, high production costs made biofuels unprofitable without subsidies. Biodiesel provides sufficient environmental advantages to merit subsidy. Transportation biofuels such as synfuel hydrocarbons or cellulosic ethanol, if produced from low-input biomass grown on agriculturally marginal land or from waste biomass, could provide much greater supplies and environmental benefits than food-based biofuels.
Road safety and drink‐driving: the knowledge and opinions of male and female adolescents
Authors: MOORE ANYA , CONNOR BRIAN H. , PAPDAKIS ELIM , FREEBODY PETER
Published: July 2006

This paper reports on a structured questionnaire survey of high school students from years 8, 9 and 10 and their knowledge and opinions on issues relating to general road safety and drink‐driving. A representative sample of this larger group was then interviewed in more depth. The results are discussed in terms of previous surveys of adolescents' attitudes and knowledge on these issues and the educational questions that arise in the light of reported sex differences.
The demand for alcohol in Australia
Authors: HAQUE MOHAMMED O.
Published: July 2006

Beers, wines and spirits differ in price, alcohol content, colour, taste and smell. These affect market demand. This paper gives an overview of consumption patterns of some broadly defined alcohol items in Australia, using data from a major household expenditure survey. Total expenditure elasticities for various alcohol items have been estimated from a new Engel function which can be called the double semi‐log Engel function. Beer had the lowest elasticity, whereas the values for wine and spirits were much higher, placing them in the ‘luxury’ category. The percentage changes in demand due to changes in total expenditures and total expenditure inequalities were also calculated. It showed that the per capita changes in demand for beer and wine were inaccurate unless income distribution was considered. This technique can also be used to determine the level of consumption demand for various alcohol items.
The contribution of Wernicke's encephalopathy to alcohol‐related cerebellar damage
Authors: PHILLIPS STEPHEN C. , HARPER CLIVE G. , KRIL JILLIAN J.
Published: July 2006

Mid‐sagittal histological sections of the cerebellar vermis were prepared for light microscopy from six patients with Wernicke's encephalopathy, 13 alcoholics and 16 normal controls. From Nissl stained sections, the Wernicke's encephalopathy group was found to have a significant 29% lower Purkinje cell count relative to controls, while the alcoholic group had a non‐significant 10% lower cell count. The degree of shrinkage of the molecular layer paralleled the degree of Purkinje cell loss. Damage to the medullary layer in the form of shrinkage in Nissl sections and torpedo formation in silver sections did not correlate as well with Purkinje cell loss. Thiamine deficiency would seem to be a significant contributing factor to the neuropathology of cerebellar damage seen in alcoholism. The presence or absence of cirrhosis of the liver was also found to influence the degree of Purkinje cell loss.
Quality assurance in drug and alcohol treatment: the development of standards for treatment content
Authors: MATTICK RICHARD P. , GRENYER BRIN F.
Published: July 2006

The need for minimum standards of service delivery in drug and alcohol treatment agencies is outlined, and the Australian standards developed to date are discussed. It is argued that such standards are insufficient to assure the efficacy of treatment approaches used in treatment agencies, although they are an important and necessary precursor to the implementation of patterns of optimum care. The nature of optimum care standards is outlined and one methodology for developing optimum standards is described.
Women with alcohol problems: a psycho‐social perspective
Authors: BAILY SALLY
Published: July 2006

In this paper, women's alcohol use and related problems are examined and special reference is given to the various psycho‐social factors involved. The need for a special treatment approach for women is discussed and the lack of knowledge in this area highlighted. The areas of alcohol relapse and women‐only groups are explored as possible areas for future development and research.
Motivation and addiction behaviour: a psychological perspective
Authors: SAUNDERS BILL , WILKINSON CELIA
Published: July 2006

In this paper traditional ideas about motivation and the addiction behaviours are critically considered. It is proposed that rather than viewing motivation as a static quality that clients either have or have not, motivation is more usefully perceived as the balance between the costs and benefits of undertaking any behaviour, juxtaposed with the costs and benefits of ceasing the behaviour. It is also proposed that confrontation approaches, rather than inducing motivation, actually increase the client's resistance. Motivational interventions therefore need to be based on a client‐generated inventory of problems and concerns rather than a therapist‐dictated one. A decision‐making framework for motivational intervention is emphasized and the effectiveness of motivational strategies based on this paradigm is considered.
Can microcomputers help the problem drinker?
Authors: ELTRINGHAM ANDREW , BARBER JAMES G.
Published: July 2006

The evidence in favour of brief interventions and self‐help materials for problem drinkers raises the possibility that microcomputer programmes can provide an effective and inexpensive treatment option in the addictions field. This paper reports on a controlled drinking computer programme currently in operation with drink driving offenders.
Gambling: the psychology of a non‐drug compulsion
Authors: DICKERSON MARK
Published: July 2006

In 1968 an editorial in the British Medical Journal rejected the view that compulsive or pathological gambling should be included under the rubric of illness. Exactly 20 years later an invited paper to the same journal noted that the problem was an addictive behaviour or dependency disorder and listed the American Psychiatric Association's diagnostic criteria. The following review critically evaluates some of the key conceptual and research developments during the intervening period.
Two‐month follow‐up on callers to a telephone quit smoking service
Authors: BORLAND RON , HILL DAVID
Published: July 2006

The results of a 2‐month follow‐up on a sample of individuals who rang a telephone quit smoking service to get advice on how to quit smoking are reported. Calls were in response to large‐scale media campaigns carried out in Victoria each year from 1984 through 1986. The calls to the service came more from women than men and tended to come from better educated white collar workers. There were few differences in short‐term quit rates as a function of basic demographic variables. There was some evidence that after 3 years of campaigning a greater proportion of telephone service users were making a major effort to quit and that younger smokers at whom the campaign was directed were more likely to quit.
Extending upon student drinking patterns in an Australian population
Authors: O'CALLAGHAN FRANCES , WILKS JEFFREY , CALLAN VICTOR J.
Published: July 2006

One hundred and twenty‐two students from the University of Queensland were surveyed regarding their attitudes and behaviour toward alcohol. As an extension of earlier investigations at the same university the study provides some monitoring of drinking levels over 8 years. Results indicate that the quantity and frequency of male consumption continues to be greater than that of females. Sex differences were also evident in beverage preferences. An increase in the proportion of males drinking more than 40 grams of alcohol per day was noted. The implications of this finding are discussed within the broader context of comparisons across studies and with reference to National Health and Medical Research Council recommendations for alcohol consumption.
The role of general practitioners in the delivery of drug and alcohol services to ethnic minority communities
Authors: ALCORSO CAROLINE
Published: July 2006

There has been increased emphasis on the need for early intervention in the treatment of drug and alcohol problems and on reducing consumption among ‘low‐risk’ as well as among more heavily drug‐dependent populations. At the same time, the doctor's role in recognising and treating drug and alcohol problems among their clients has been coming under closer scrutiny. An Illawarra‐based study has examined these questions in the context of two non‐English speaking background communities. Our findings are relevant not only to attempts to reconstruct the doctor‐patient relationship, but to the question of health service provision in a multiethnic society generally.
The drug use behaviour of cocaine users
Authors: MOOSBURGER RENATE , PLANT AILEEN J. , PIERCE JOHN P.
Published: July 2006

We interviewed 50 current cocaine users with the aim of providing insights into cocaine use in Sydney. The study sample was obtained by one researcher using a chain referral technique. Appointments were made for interview and the interview aimed to determine the quantity, frequency, pattern and circumstances of drug use in the respondents. The study sample included people with a wide range of incomes and occupations; all but one person were employed. Extensive current drug use was reported; 78% smoked tobacco, 98% drank alcohol with 36% having more than two drinks per day, 96% used marijuana with 40% smoking marijuana at least 5 times per week, 65% used amphetamines, 36% used hallucinogens and 10% used heroin. Ten per cent were unable to name one health risk of cocaine. When asked about the image of a cocaine user, 42% thought of a rock star, film industry worker or someone involved in the arts and entertainment world. The information obtained from a study such as this provides important data for targeting of people in anti‐drug campaigns.
Spirituality: the silent dimension in addiction research. The 1990 Leonard Ball oration
Authors: MILLER WILLIAM R.
Published: July 2006

Researchers currently recognize and incorporate psychological, biomedical, and social determinants in the study of addictive behaviors. Yet spiritual aspects of addiction and recovery remain virtually unstudied, despite the fact that spirituality is given central importance in Alcoholics Anonymous and in the lives of many individuals. Traditional spiritual concepts have been relabelled to remove their transcendent dimension, and addiction researchers have acted as though spirituality plays no role in the lives of those they study. Consequently an entire class of potentially important variables is being overlooked. A majority of variance in addictive behaviors and treatment outcomes remains unexplained, a portion of which might be accounted for through the study of spiritual dependent, moderator, and independent variables. Behavioural scientists have begun to acknowledge the role of complex spiritual, moral, and decisional processes in the addictive behaviours. Though uncomfortable in some ways for both believers and unbelievers, the scientific study of spiritual processes may improve our understanding of the addictive behaviours, and our ability to prevent and treat these enduring problems.