253 research outputs found

    Winners and Losers: Spatial variations in labour productivity in England and Wales

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    This paper presents an investigation into the static and dynamic spatial pattern of aggregate labour productivity across England and Wales at the district and unit authority level. This analysis is complemented by plant-level regressions to identify the contribution of industrial sectors to each NUTS1 region’s average labour productivity. Using data for 1998 and 2005, our exploratory data analysis illustrates that there are stable spatial patterns in levels of labour productivity and that labour productivity change does not appear to be spatially dependent, at least not at this spatial scale. Furthermore the economic importance of different sectors to different regions evolves over time, which makes regional industrial policy formation problematic.Labour productivity; districts and local authorities; sectors; spatial autocorrelation

    Microeconomic foundations of geographical variations in labour productivity

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    This paper initially presents an exploratory spatial data analysis which indicates the presence of small-scale geographical variations in levels and standard deviations of labour productivity across England and Wales in 2005. We identify the presence of spatial autocorrelation for both measures. This finding motivates a subsequent review and extension of theories which suggest the possible presence of small-scale geographical patterns of labour productivity.Labour productivity; standard deviation; districts and local authorities; geographical autocorrelation

    Synthesis and characterization of graphene/polythiophene (GR/PT) nanocomposites:Evaluation as high-performance supercapacitor electrodes

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    Composites of polythiophene (PT) and graphene (GR) with different mass proportions were studied for their application as supercapacitors. Fourier transform infrared spectroscopy (FTIR) along with High Resolution Scanning electron microscopy (HR-SEM) were employed in order to characterize the morphology and composition of the resulting composites. The electrochemical behaviour of these composites was studied by means of cyclic voltammetry and specific capacitance curves were derived from these measurements. The Faradaic impedance spectroscopy response of the different composites, along with that of GR, was also studied. From these measurements it was found that a 1:1 in mass composite of GR and PT showed a higher specific capacitance, even when compared with GR alone. The introduction of the GR in that proportion also showed an enhanced cyclic stability in comparison with the sole polymer. The high specific capacitance (365 F g-1 at 1 A g-1) of this composite material indicates its potential for use as an electrode material for supercapacitors.Fil: Melo, J. P.. Universidad Bernardo OHiggins; ChileFil: Schulz, Eduardo NicolĂĄs. Universidad Nacional del Sur. Departamento de IngenierĂ­a QuĂ­mica. Instituto de IngenierĂ­a ElectroquĂ­mica y CorrosiĂłn; Argentina. University of Birmingham; Reino UnidoFil: Morales Verdejo, C.. Universidad Bernardo OHiggins; ChileFil: Horswell, S. L.. University of Birmingham; Reino UnidoFil: Camarada, M. B.. Universidad Bernardo OHiggins; Chil

    Mobility and survival of Salmonella Typhimurium and human adenovirus from spiked sewage sludge applied to soil columns

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    Aims: This study investigated the survival and transport of sewage sludge-borne pathogenic organisms in soils. Methods and Results: Undisturbed soil cores were treated with Salmonella enterica ssp. enterica serovar Typhimurium-lux (STM-lux) and human adenovirus (HAdV)-spiked sewage sludge. Following an artificial rainfall event, these pathogens were analysed in the leachate and soil sampled from different depths (0-5 cm, 5-10 cm and 10-20 cm) after 24 h, 1 and 2 months. Significantly more STM-lux and HAdV leached through the soil cores when sewage sludge was present. Significantly more STM-lux were found at all soil depths, at all time periods in the sewage sludge treatments, compared to the controls. The rate of decline of STM-lux in the controls was more rapid than in the sewage sludge treatments. Survival and transport of HAdV were minimal. Conclusions: The presence of sewage sludge can significantly influence the transport and survival of bacterial pathogens in soils, probably because of the presence of organic matter. Environmental contamination by virus is unlikely because of strong soil adsorption. Significance and Impact of the Study: This study suggests that groundwater contamination from vertical movement of pathogens is a potential risk and that it highlights the importance of the treatment requirements for biosolids prior to their application to land

    Palladium nanoparticles by electrospinning from poly(acrylonitrile-co-acrylic acid)-PdCl2 solutions. Relations between preparation conditions, particle size, and catalytic activity

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    Catalytic palladium (Pd) nanoparticles on electrospun copolymers of acrylonitrile and acrylic acid (PAN-AA) mats were produced via reduction of PdCl2 with hydrazine. Fiber mats were electrospun from homogeneous solutions of PAN-AA and PdCl2 in dimethylformamide (DMF). Pd cations were reduced to Pd metals when fiber mats were treated in an aqueous hydrazine solution at room temperature. Pd atoms nucleate and form small crystallites whose sizes were estimated from the peak broadening of X-ray diffraction peaks. Two to four crystallites adhere together and form agglomerates. Agglomerate sizes and fiber diameters were determined by scanning and transmission electron microscopy. Spherical Pd nanoparticles were dispersed homogeneously on the electrospun nanofibers. The effects of copolymer composition and amount of PdCl2 on particle size were investigated. Pd particle size mainly depends on the amount of acrylic acid functional groups and PdCl2 concentration in the spinning solution. Increasing acrylic acid concentration on polymer chains leads to larger Pd nanoparticles. In addition, Pd particle size becomes larger with increasing PdCl2 concentration in the spinning solution. Hence, it is possible to tune the number density and the size of metal nanoparticles. The catalytic activity of the Pd nanoparticles in electrospun mats was determined by selective hydrogenation of dehydrolinalool (3,7-dimethyloct-6- ene-1-yne-3-ol, DHL) in toluene at 90 °C. Electrospun fibers with Pd particles have 4.5 times higher catalytic activity than the current Pd/Al2O3 catalyst

    Effects of Low-Dose Gestational TCDD Exposure on Behavior and on Hippocampal Neuron Morphology and Gene Expression in Mice.

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    BACKGROUND: 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a persistent and toxic environmental pollutant. Gestational exposure to TCDD has been linked to cognitive and motor deficits, and increased incidence of autism spectrum disorder (ASD) traits in children. Most animal studies of these neurodevelopmental effects involve acute TCDD exposure, which does not model typical exposure in humans. OBJECTIVES: The aim of the study was to establish a dietary low-dose gestational TCDD exposure protocol and performed an initial characterization of the effects on offspring behavior, neurodevelopmental phenotypes, and gene expression. METHODS: Throughout gestation, pregnant C57BL/6J mice were fed a diet containing a low dose of TCDD (9 ng TCDD/kg body weight per day) or a control diet. The offspring were tested in a battery of behavioral tests, and structural brain alterations were investigated by magnetic resonance imaging. The dendritic morphology of pyramidal neurons in the hippocampal Cornu Ammonis (CA)1 area was analyzed. RNA sequencing was performed on hippocampi of postnatal day 14 TCDD-exposed and control offspring. RESULTS: TCDD-exposed females displayed subtle deficits in motor coordination and reversal learning. Volumetric difference between diet groups were observed in regions of the hippocampal formation, mammillary bodies, and cerebellum, alongside higher dendritic arborization of pyramidal neurons in the hippocampal CA1 region of TCDD-exposed females. RNA-seq analysis identified 405 differentially expressed genes in the hippocampus, enriched for genes with functions in regulation of microtubules, axon guidance, extracellular matrix, and genes regulated by SMAD3. DISCUSSION: Exposure to 9 ng TCDD/kg body weight per day throughout gestation was sufficient to cause specific behavioral and structural brain phenotypes in offspring. Our data suggest that alterations in SMAD3-regulated microtubule polymerization in the developing postnatal hippocampus may lead to an abnormal morphology of neuronal dendrites that persists into adulthood. These findings show that environmental low-dose gestational exposure to TCDD can have significant, long-term impacts on brain development and function. https://doi.org/10.1289/EHP7352

    A selective blocking method to control the overgrowth of Pt on Au nanorods

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    [Image: see text] A method for the preparation of smooth deposits of Pt on Au nanorods is described, involving sequential deposition steps with selective blocking of surface sites that reduces Pt-on-Pt deposition. The Au–Pt nanorods prepared by this method have higher long-term stability than those prepared by standard Pt deposition. Electrochemical data show that the resulting structure has more extended regions of Pt surface and enhanced activity toward the carbon monoxide oxidation and oxygen reduction reactions
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