70 research outputs found
Water rights and environmental damage: an enquiry into stewardship in the context of abstraction licensing reform in England and Wales
The intersection of private rights and public responsibilities lies at the heart of both environmental and property law. This article considers this intersection in the context of debates about property ownership and notions of environmental stewardship. These form the background to considering shifts in water rights law in England and Wales and the extent to which they can be said to exhibit or exemplify a shift towards stewardship. Section 27 of the Water Act 2003 is analysed as this authorises revocation or variation of an abstraction licence without compensation in order to protect waters or aquatic flora and fauna from āserious damageā. Because regulatory abstraction licensing is a modern overlay on the common law, but one which has protected many existing abstractors from restrictions on their rights, section 27 might be regarded as strongly indicative of a stewardship shift in water rights. However, I argue that greater attention needs to be paid to the wider context within which this provision operates before it can be deployed as an unambiguous pro-stewardship example. I suggest that a range of related regulatory, economic and interpretive factors are likely to lead in practice to limited direct legal intrusion on private water rights. The case of section 27 serves as a ābottom upā example of a need for circumspection about whether any specific formal, doctrinal reform is likely to exemplify, or support, a shift towards stewardship in water or property law, and draws out some of the complex relations between public and private interests than characterise stewardship
Recognising an ecological ethic of care in the law of everyday shared spaces
Law plays a vital role in the life and loss of open shared spaces, used and enjoyed on an everyday basis by local people. In this article, we adopt an analytical framework based on an ethic of care to critique the registration of land as a ātown or village greenā, using the example of an inquiry into the greens status of an ancient woodland. Analysing written and oral witness statements in this inquiry makes clear the centrality of such places in many peopleās lives, giving rise to community-based, and forward-looking, interests. However, the legal focus upon quantitative assessments of individualsā use of land in the recent past means that the prospective consequences of losing such valued areas are currently poorly acknowledged, and accounted for, in the registration process. This leads to the question whether an ethic of care towards everyday shared spaces may be better recognised via more deliberative plan-making regimes
Bringing environmental justice to the centre of environmental law research: developing a collective case study methodology
Drawing on classic studies of environmental justice, as well as our smaller scale experience of using case studies to research environmental assessment and the protection of open green spaces, we suggest that collective case studies (also known as multisite or multiple case studies) offer an opportunity to map out and realise common concerns and losses and the similar experiences of legal hurdles and challenges on the part of geographically disparate local communities. The collective nature of these studies helps to build up a picture of environmental injustices across different, but related, cases and are capable of revealing broad discriminatory and unfair practices in environmental decision making which may form part of a pattern of experiencing discrimination and lack of influence and participation in decision making extending beyond the specifics of a particular site, environmental conflict or legal dispute. In this respect, the development of collective case studies provides a method of research practice but may also contribute to the generation or development of theories of environmental justice, crossing the line between specificity/context of experience in a locality and generality/unity of theory
Enhanced Conducting Polymer PEDOT:PSS/ Silicon Hybrid Solar Cells: Optimization of Thin Film Properties and Heterojunction Interactions
In this work the operating properties of PEDOT:PSS - silicon hybrid solar cells were carefully studied. The motivation is to find a cost-effective alternative to some of the energy, environmental and sustainability issues the world is currently facing. Solar cells are already providing plentiful renewable energy but they remain constrained by inflexibility, weight, cost and efficiency. Overcoming these obstacles will allow these energy producing devices to become widespread and, along with them, new technologies and economies to emerge. Hybrid solar cells (HSCs) address these issues by junctioning conducting polymer with an inorganic semiconductor. The beneficial properties of these materials can be exploited to improve the cost effectiveness, flexibility, and ease of processing of the polymer, and the electron lifetime and diffusion length, and stability of the inorganic material. PEDOT:PSS and n-type silicon is one such HSC with easily reproducible high efficiencies around 12% that could greatly reduce the cost per watt ratio and other challenges associated with conventional silicon solar cells.
In Chapter 2, the material properties of inorganic semiconductors, focusing on silicon, are introduced and the details of Schottky junctions, p-n junction and solar cells properties are discussed. These properties are compared and contrasted with conducting polymers, focusing on PEDOT:PSS, which function in a fundamentally different way from inorganics in that charge mobility is much more limited to intra or inter molecular transport. Finally the physics behind thin films and surfaces for the absorbance of light is examined.
In Chapter 3, a novel method of increasing the conductivity of PEDOT:PSS was found by post-treating pre-deposited films with a 50 vol% ethylene glycol/methanol mixture. This post-treatment method more than doubled the conductivity to 1334 S/cm over the method of adding an ethylene glycol co-solvent to the PEDOT:PSS solution (637 S/cm). It also reduced the film thickness in half (51%) due to the removal of PSS. The treatment resulted in PEDOT to have a greater quinoidal character, and because of the decrease in PSS, more defined PEDOT containing nanodomains with the chains laying horizontal to the substrate.
In Chapter 4, the optical properties of the films were studied using a single stack layer to model the reflectance of PEDOT:PSS on silicon and to determine the effects of film thickness on short circuit current density (JSC). Using the complex refractive index, the reflection of PEDOT:PSS films and silicon respectively, and the phase shifts found from fitting experimental transmittance and reflectance data, the external quantum efficiency (EQE) for the cells could be simulated. The JSC calculated from these results showed that JSC followed a sigmoidal curve and the highest value 28.3 mA/cm2 was obtained at a thickness of 85 nm. Interestingly, the post-treated cells had overall lower JSC with a maximum of 26.2 mA/cm2 at 63 nm due to the increased anisotropy, absorbance and series resistance. A comparative measure of resistivity was performed by removing the optical component from the quantum efficiency to reveal the electrical contributions and by fitting the data using a modified single diode equivalent circuit. This indicated that the resistivity was 75% higher for the post-treated films over the co-solvent films. Using the absorbance, reflectance, and EQE models for the optimal thickness of 85 nm, the optical generation and loss mechanisms could be calculated: 61.5% of the incident light was converted into current, 22.2% was lost to reflectance, 6.9% was absorbed by the film, 2.7 was absorbed by the rear electrode, and 6.7 was lost to recombination at the surface and in the bulk silicon.
In Chapter 5, the PEDOT:PSS/silicon heterojunction was studied and the influence of passivation layers was examined using dark current density curves and the open-circuit voltage of the cell. It was discovered that the size of the native silicon oxide layer could be determined by the blue shift in the Raman CĪ± =CĪ² band. It was noted that the native oxide continued to grow uninterrupted after PEDOT:PSS was deposited on hydrogen-terminated silicon resulting in a contaminated native oxide layer with decreased performance. It was concluded that the contamination at the surface, increased defects and Fermi level pinning could cause a decrease in band bending, leading to increased carrier recombination and poor performance. Allowing a controlled native oxide layer to grow to 2 nm in a clean environment increased the inversion layer and performance. The increase in bi-polaron modes with post-treatment together with the increased concentration of PEDOT and the effective density of acceptor states resulting from the removal of PSS, caused a stronger inversion and electron blocking at the interface.
Finally in Chapter 5, P3HT was used as an interfacial layer between PEDOT:PSS and silicon. It was found that spin-coating a solution of P3HT dispersed in dichlorobenzene on silicon produced a homogeneous layer of small interconnected nanocrystallites. When applied to HSCs, no charge separation or transfer originating from the P3HT chromophore could be detected indicating the inversion layer existed entirely within the silicon substrate. However the larger open circuit voltage and change in dark saturation current undedicated the layer blocked electron majority carrier transfer from the silicon, increasing shunt resistance and open-circuit voltage.
By combining the research of into short-circuit current density, and open-circuit voltage, it was concluded that the highest achievable efficiency of the setup used in this research was 11.8%
Synthesis and characterization of nanostructured catalysts for photovoltaic applications
The objective of this project was to investigate the effect of the morphology of titanium
dioxide (TiO2) nanoparticles on the electron transport properties and light harvesting potential in
a dye sensitized solar cell (DSSC). Particular attention was given to develop synthetic methods
to produce metal oxide photocatalysts with similar crystallite size, with different morphologies
(spheres, fibers, hierarchical spheres, and globular structures) with the aim of studying the
relationship between morphology and photocatalytic activity. The addition of CNTs to the
synthesis showed that they acted as nucleation sites and altered the morphology. Materials were
fully characterized using Raman, SEM, XRD, BET, and FTIR.
The photocatalytic activity of the as-synthesized materials was tested in a DSSC
configuration and characterized using electrochemical impedance spectroscopy. It was found that
the different morphologies had different light scattering properties which influenced the
efficiencies. Based on these preliminary results, the nanofibres prepared in heptane performed
the best, with good dye loading, electron lifetime and diffusion coefficient. The addition of a
scattering layer using hierarchical spheres showed promising results in decreased transparency
and increased efficiency. The addition of CNTs had an adverse effect, this could be due to light
blocking by the black CNTs and increased recombination with the electrolyte
Mitigation and screening for environmental assessment
This article considers how, as a matter of law and policy, mitigation measures should be taken into account in determining whether a project will have significant environmental effects and therefore be subject to assessment under the EU Environmental Impact Assessment (EIA) Directive. This is not straightforward: it is problematic to distinguish clearly between an activity and the measures proposed to minimise or mitigate for the adverse consequences of the activity. The issue is a salient one in impact assessment law, but under-explored in the literature and handled with some difficulty by the courts. I argue that there is an unnecessarily and undesirably narrow approach currently taken under the EIA Directive, which could be improved upon by taking a more adaptive approach; alternatively a heightened standard of review of āsignificanceā, and within this of the scope for mitigation measures to bring projects beneath the significance threshold, may also be desirable
AND/R: Advanced neutron diffractometer/reflectometer for investigation of thin films and multilayers for the life sciences
An elastic neutron scattering instrument, the advanced neutron diffractometer/reflectometer (AND/R), has recently been commissioned at the National Institute of Standards and Technology Center for Neutron Research. The AND/R is the centerpiece of the Cold Neutrons for Biology and Technology partnership, which is dedicated to the structural characterization of thin films and multilayers of biological interest. The instrument is capable of measuring both specular and nonspecular reflectivity, as well as crystalline or semicrystalline diffraction at wave-vector transfers up to approximately 2.20 Ć
(-1). A detailed description of this flexible instrument and its performance characteristics in various operating modes are given.D. J. M. is supported
through a NSF NIRT grant Contract No. 0304062
AND/R: Advanced neutron diffractometer/reflectometer for investigation of thin films and multilayers for the life sciences
Anthrax Toxins Inhibit Neutrophil Signaling Pathways in Brain Endothelium and Contribute to the Pathogenesis of Meningitis
Anthrax meningitis is the main neurological complication of systemic infection with Bacillus anthracis approaching 100% mortality. The presence of bacilli in brain autopsies indicates that vegetative bacteria are able to breach the blood-brain barrier (BBB). The BBB represents not only a physical barrier but has been shown to play an active role in initiating a specific innate immune response that recruits neutrophils to the site of infection. Currently, the basic pathogenic mechanisms by which B. anthracis penetrates the BBB and causes anthrax meningitis are poorly understood.Using an in vitro BBB model, we show for the first time that B. anthracis efficiently invades human brain microvascular endothelial cells (hBMEC), the single cell layer that comprises the BBB. Furthermore, transcriptional profiling of hBMEC during infection with B. anthracis revealed downregulation of 270 (87%) genes, specifically key neutrophil chemoattractants IL-8, CXCL1 (Gro alpha) and CXCL2 (Gro beta), thereby strongly contrasting hBMEC responses observed with other meningeal pathogens. Further studies using specific anthrax toxin-mutants, quantitative RT-PCR, ELISA and in vivo assays indicated that anthrax toxins actively suppress chemokine production and neutrophil recruitment during infection, allowing unrestricted proliferation and dissemination of the bacteria. Finally, mice challenged with B. anthracis Sterne, but not the toxin-deficient strain, developed meningitis.These results suggest a significant role for anthrax toxins in thwarting the BBB innate defense response promoting penetration of bacteria into the central nervous system. Furthermore, establishment of a mouse model for anthrax meningitis will aid in our understanding of disease pathogenesis and development of more effective treatment strategies
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