The polyglot community: an interview with Richard Simcott, by Tita Beaven

The closing plenary session at the InnoConf17 conference was an informal interview that Tita Beaven conducted with Richard Simcott, which we reproduce here in an edited version

The hydrogeological and geotechnical properties of household waste in relation to sustainable landfilling.

PhDThis thesis reports an investigation into the hydrogeological and geotechnical properties of household wastes within the context of sustainable landfilling and, particularly, the development of a high rate flushing bioreactor. The design and construction of a large-scale (2-metre diameter) purpose built compression cell used in the research are described. Tests on a number of different household waste materials (including pulverised and aged wastes) were undertaken at varying applied loads up to 600 kPa, equivalent to a 60 metre depth of landfill. Results of variations in refuse density, stiffness, absorptive capacity, effective porosity and hydraulic conductivity are reported against average effective stress in the waste. It was concluded that the hydrogeological properties of household waste vary considerably with effective stress and, hence, with depth in landfills. For example, the hydraulic conductivity of crude household waste could reduce by over three orders of magnitude from approximately lxi O mis to lxi 4 rn/s between placement (with minimal compaction) and burial to a depth of 60 metres. The principles of sustainable development are considered and applied to landfilling. The view that the polluting potential of landfills should be reduced to acceptable levels within a generation is supported. In most cases this will require that contaminants in the landfill are removed by introducing water into the site and recirculating and flushing leachate from it. The feasibility of achieving this with a variety of different leachate recirculation systems is examined in the light of the findings of the research. A new module has been written for MODFLOW, the USGS's groundwater flow model, to allow hydraulic conductivity to vary throughout simulations with effective stress. The altered code is used to model a grid of leachate abstraction and injection wells to illustrate the potential for flushing. It is concluded that changes are needed to current landfill design and operational practices to enable wastes to be flushed efficiently within landfills. It is argued, in particular, that there are significant benefits of operating landfills with large saturated zones.Waste Technical Division of the department of thr Environment and Cleanaway Ltd

Characterizing Residue-Bilayer Interactions Using Gramicidin A as a Scaffold and Tryptophan Substitutions as Probes

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Chemical Theory and Computation, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/acs.jctc.7b00400.Previous experiments have shown that the lifetime of a gramicidin A dimer channel (which forms from two non-conducting monomers) in a lipid bilayer is modulated by mutations of the tryptophan (Trp) residues at the bilayer-water interface. We explore this further using extensive molecular dynamics simulations of various gA dimer and monomer mutants at the Trp positions in phosphatidylcholine bilayers with different tail lengths. gA interactions with the surrounding bilayer are strongly modulated by mutating these Trp residues. There are three principal effects: eliminating residue hydrogen bonding ability (i.e., reducing the channel-monolayer coupling strength) reduces the extent of the bilayer deformation caused by the assembled dimeric channel; a residue’s size and geometry affects its orientation, leading to different hydrogen bonding partners; and increasing a residue’s hydrophobicity increases the depth of gA monomer insertion relative to the bilayer center, thereby increasing the lipid bending frustration

Systematic Analysis of Lower Second Molar Periodontal Health after Autogenous Dentine Graft from Wisdom Tooth Extraction

Introduction: Postoperative complications stemming from lower wisdom tooth extractions are often overshadowed by the immediate need to address pain and existing disease. Nevertheless, an emerging body of evidence suggests the importance of preventing potential periodontal damage to the adjacent second molar resulting from the extraction surgery. To avert periodontal complications involves promoting bone formation within the extracted socket defect. Allogenic and artificial bone, as well as the patient’s bone, have conventionally filled the osseous void post-surgery. These approaches are costly and may extend the patient’s recovery. An Autogenous Dentine Graft (ADG), derived from the recently extracted wisdom tooth, presents, as a particulate with osteoconductive and osteoinductive properties, is ideal for preserving bone integrity. This review assesses the available evidence supporting the use of ADG in safeguarding against periodontal morbidity resulting from the surgical extraction of a lower third molar. Materials and methods: A systematic review of the literature was conducted, focusing on the periodontal health of the second molar and the bone height of the osseous defect postwisdom tooth extraction. Out of 76 identified articles, four studies were selected for the review. Results: Three months post-surgery, the mean periodontal probing depth distal to the second molar was 4.7mm in control sites and 2.83mm in sites treated with ADG. Over 12 months, the mean bone height exhibited a negative loss of 1.25mm in control sites and a positive gain of 0.9mm in sites treated with ADG. Conclusion: Presently, there is insufficient evidence to unequivocally support the use of an autogenous dentine graft following the surgical extraction of a wisdom tooth. However, early results are promising, and given the biocompatibility of a material derived from the patient, ADG is considered a safe option for patients at high risk of an osseous defect. Further research is needed to substantiate these findings and guide clinical decision-making

A near-field Gaussian plume inversion flux quantification method, applied to unmanned aerial vehicle sampling

The accurate quantification of methane emissions from point sources is required to better quantify emissions for sector-specific reporting and inventory validation. An unmanned aerial vehicle (UAV) serves as a platform to sample plumes near to source. This paper describes a near-field Gaussian plume inversion (NGI) flux technique, adapted for downwind sampling of turbulent plumes, by fitting a plume model to measured flux density in three spatial dimensions. The method was refined and tested using sample data acquired from eight UAV flights, which measured a controlled release of methane gas. Sampling was conducted to a maximum height of 31 m (i.e. above the maximum height of the emission plumes). The method applies a flux inversion to plumes sampled near point sources. To test the method, a series of random walk sampling simulations were used to derive an NGI upper uncertainty bound by quantifying systematic flux bias due to a limited spatial sampling extent typical for short-duration small UAV flights (less than 30 min). The development of the NGI method enables its future use to quantify methane emissions for point sources, facilitating future assessments of emissions from specific source-types and source areas. This allows for atmospheric measurement-based fluxes to be derived using downwind UAV sampling for relatively rapid flux analysis, without the need for access to difficult-to-reach areas

Review of responses to a landfill modelling Challenge

This paper reviews the responses from various international research groups to a challenge to model and predict the performance of a well-constrained laboratory experiment on the settlement and biodegradation of municipal solid waste (MSW). The paper outlines and compares the modelling approaches taken by the various groups and compares their predictions against actual long-term data from the experiment. The opportunity to compare models side-by-side against a common dataset has been extremely valuable in highlighting differences in approach, input parameters and identifying areas that need further investigation. One of the main differences identified related to hydrolysis, with three different algorithms used. Within the context of this modelling challenge it was not clear which was the appropriate formulation to use and thus the need for further work in this area was highlighted. This is also an example where the need to standardise on one pathway (or algorithm) could be investigated. There appears to be a clear imperative for settlement models to include a component for mechanical creep. An objective of the modelling challenge was to create a framework by which various models can be compared and act as a starting point for discussion and further collaboration in the future. This paper forms a starting point to this process

Landfill gas emission monitoring: Editorial to Special Issue

Countries that have ratified the 1994 United Nations Framework Convention on Climate Change have an obligation to report national emission inventories of greenhouse gases (GHGs), which include contributions from landfill methane. Fugitive emissions of landfill gas (LFG) in 2010 were estimated to account for approximately 8% of the global anthropogenic emissions of methane to the atmosphere (Fischedick et al., 2014). Currently, landfill gas emission reporting is largely based on estimations using gas generation models. Methods for monitoring methane emissions from landfills are generally poor and there is a need to develop more robust methodologies and encourage their uptake within the industry in general. The collection of papers in this Special Issue, together with a number of other papers recently published in Waste Management, draw together recent developments in the topic of LFG emission monitoring techniques