1,721,265 research outputs found
Advancing biosensing techniques for detection of antimicrobial resistance genes and antibiotics in water
Get PDFCoulon, Frederic - Associate SupervisorAntimicrobial resistance (AMR) poses a significant global public health threat
requiring urgent attention for surveillance of antibiotic resistance genes (ARGs)
and antibiotics in the environment. In this PhD study, a real-time fluorescent
detection assay of antimicrobial resistance genes (ARGs) was developed to
specifically target two key ARGs, tet(M) and tet(x3) to detect tetracycline and
tigecycline resistance respectively in water samples. Additionally, crassphage
gene was investigated for anthropogenic activities since they also play a vital role
in the AMR transmission. The advanced ARG detection assay was based on
multiplexing recombinase polymerase amplification (RPA) and subsequent
sequence-specific recognition by the trans-cleavage activity of Clustered
Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas12a. The assay
achieved limits of detection (LODs) of 1 copy µL⁻¹ for all three gene targets with
an accuracy of 100% in spiked tap and surface water samples.
Expanding the assay by including two additional end-point detection modalities,
lateral flow assay (LFA) and voltametric detection, further demonstrate its
versatility. LODs of 1 copy µL⁻¹ for tet(x3) and crassphage, and 10 copies µL⁻¹
for tet(M) (LFA) and 10 copies µL⁻¹ for all three targets (electrochemical) were
reached. Validation against gold standard quantitative polymerase chain reaction
(qPCR) using real water samples, including wastewater and drinking water
samples, revealed a remarkable 100% accuracy rate.
Antibiotics detection assay was conceptualised based on the amplification of
hybridisation chain reaction (HCR) followed by CRISPR/Cas mediated cleavage
within a DNA hydrogel matrix. This approach aimed to release electroactive
methylene blue (MB) particles, detectable and quantifiable by square wave
voltammetry (SWV). While unforeseen circumstances impeded full assay
development, the preliminary data illustrated the viability of the proposed method,
suggesting avenues for further research to develop rapid and onsite antibiotics
detection methods.PhD in Wate
Soil bioengineering for sustainable bioremediation of oil contaminated soils.
Get PDFCoulon, Frederic - Associate SupervisorContaminated soils arising from the petroleum industry remains a major problem globally,
resulting in levels of petroleum hydrocarbons and metals that are dangerous to the environment.
Modern remediation strategies focus on sustainability, thus maximizing environmental, social,
and economic benefits. The use of materials derived from agricultural and industrial waste, for
example biochar and spent mushroom compost (SMC), may provide a potential solution to
sustainable remediation strategies. Biochar has numerous properties, e.g., high surface area and
pore volume that may provide benefits to the remediation industry. SMC, a by-product of
mushroom production, may contain diverse groups of microorganisms and extracellular
enzymes important for the biotransformation of contaminants. Biochar and spent mushroom
compost interactions in soil may induces diverse responses in microbial species leading to
changes in soil enzyme activity, reshaping of microbial community structure and consequent
enhancement of contaminants transformations. However, the mechanisms underlying these
interactions are poorly understood, with unpredictable outcomes. There is a deficit of research
designed to understand their collective response on soil fungi and the subsequent benefits to
remediation success. Research needs to focus on the benefits of biochar towards affecting
contaminant bioavailability of multiple rather than single contaminants. Combining biochar
with SMC may facilitate the biodegradation of petroleum hydrocarbons in saline soils. The aim
of the research was to develop a biotechnological approach for the best use of biochar and SMC
to promote microbial remediation of soil contaminated with complex chemical mixture
contaminants (hydrocarbons and heavy metals). It provides a mechanistic understanding of the
physicochemical and biological parameters influencing the remediation approach. The study
further sheds light into the influence of low carbon soil amendment on the behaviour and fate
of heavy metal(loids) and petroleum hydrocarbons, and the underlying microbial community
responses in a genuinely contaminated soil in a four-month microcosms study, and in crude oil
and salt spiked soil in another four-month microcosms study.PhD in Environment and Agrifoo
Soil bioengineering for sustainable bioremediation of oil contaminated soils
Get PDFCoulon, Frederic - Associate SupervisorContaminated soils arising from the petroleum industry remains a major problem globally,
resulting in levels of petroleum hydrocarbons and metals that are dangerous to the environment.
Modern remediation strategies focus on sustainability, thus maximizing environmental, social,
and economic benefits. The use of materials derived from agricultural and industrial waste, for
example biochar and spent mushroom compost (SMC), may provide a potential solution to
sustainable remediation strategies. Biochar has numerous properties, e.g., high surface area and
pore volume that may provide benefits to the remediation industry. SMC, a by-product of
mushroom production, may contain diverse groups of microorganisms and extracellular
enzymes important for the biotransformation of contaminants. Biochar and spent mushroom
compost interactions in soil may induces diverse responses in microbial species leading to
changes in soil enzyme activity, reshaping of microbial community structure and consequent
enhancement of contaminants transformations. However, the mechanisms underlying these
interactions are poorly understood, with unpredictable outcomes. There is a deficit of research
designed to understand their collective response on soil fungi and the subsequent benefits to
remediation success. Research needs to focus on the benefits of biochar towards affecting
contaminant bioavailability of multiple rather than single contaminants. Combining biochar
with SMC may facilitate the biodegradation of petroleum hydrocarbons in saline soils. The aim
of the research was to develop a biotechnological approach for the best use of biochar and SMC
to promote microbial remediation of soil contaminated with complex chemical mixture
contaminants (hydrocarbons and heavy metals). It provides a mechanistic understanding of the
physicochemical and biological parameters influencing the remediation approach. The study
further sheds light into the influence of low carbon soil amendment on the behaviour and fate
of heavy metal(loids) and petroleum hydrocarbons, and the underlying microbial community
responses in a genuinely contaminated soil in a four-month microcosms study, and in crude oil
and salt spiked soil in another four-month microcosms study.PhD in Environment and Agrifoo
Enhancing bioremediation efficiency of acidic wetlands contaminated with crude oil.
Get PDFBortone, Imma - Associate Supervisor
Coulon, Frederic - Associate SupervisorCrude oil exploration and exploitation has significantly impacted the Niger Delta,
Nigeria wetlands and its ecosystems. Studies suggest that acidification is
ongoing with several acid forming and acid tolerant microbes identified in the
Niger Delta wetlands. The efficient remediation of the crude oil contaminants in
the acidified wetlands is the only alternative left to the Niger Delta for effective
ecological restoration of the environment. In this research, different combinations
of bioremediation strategies were investigated to enhance the remediation of
simulated crude oil contaminated acidic wetlands similar to the Nigeria Niger
Delta wetlands contamination conditions. A series of mesocosm experiments
subjected to wetland condition and a combination of treatments were evaluated
as follows: for biostimulation experiment, Food waste anaerobic digestate
(FWAD), and Tween 80 surfactant were individually added to the mesocosms at
10%, 20% and 30% w/w respectively with soil in the mesocosm experiments. For
bioaugmentation experiments, mesocosms were enriched with Pseudomonas
aeruginosa, Bacillus subtilis, or microbes indigenous to the crude oil spiked soil.
Sequel to the results of these experiments, an optimised combination of FWAD
(30% w/w) plus Tween 80 (30% w/w), Tween 80 (30% w/w) plus indigenous
microbes, and digestate (30% w/w) plus Tween 80 (30% w/w) plus indigenous
microbes were investigated. For each set of the experiments, pristine soil,
acidified soil, and crude oil spiked acidified soil were maintained as controls. Total
petroleum hydrocarbon (TPH) contents, soil basal respiration, and soil microbial
communities’ dynamics were measured over 112 days of the experiments. For
the biostimulation experiment, the FWAD and Tween 80 each at 30% (w/w)
resulted in the highest petroleum hydrocarbons degradation (> 87% removal in
49 days). Augmentation with indigenous microbes enhanced the extent of
degradation of the petroleum hydrocarbons (up to 80% in 49 days). For the
optimised combined strategies, digestate (30% w/w) plus Tween 80 (30% w/w)
plus indigenous microbes resulted in degradation of the hydrocarbons by > 98%.
The correlation between basal respiration, microbial community and
hydrocarbons showed that the more the biogenic CO₂ produced by the relevant
microbial community, the faster the rate of the hydrocarbons degradation. Gram
positive bacteria were the dominant microbial group in the FWAD, Tween 80
surfactant, indigenous microbes, and combined digestate (30% w/w) plus Tween
80 (30% w/w) plus indigenous microbe mesocosms. This research has
demonstrated that acidified wetlands contaminated by petroleum hydrocarbons
can be effectively remediated using low carbon biomaterials and indigenous
microbial consortia. This conclusion was further confirmed by the more than 90%
maize germination and undetectable bioavailable hydrocarbons recorded at the
end of the experiment in these mesocosms. Potential exists for further studies in
low carbon remediation of weathered hydrocarbons contaminants in various
types of wetlands and sediments using FWAD, Tween 80 surfactant, and
indigenous microbes.PhD in Energy and Powe
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Evaluation of anaerobic digestion process for derived-MBT organic solid wastes
Get PDFSemi-continuous and batch system bench-scale reactors, at mesophilic temperature, were
set-up to investigate the performance of anaerobic digestion treating mixed waste from
municipal solid collection, derived from two large-scale mechanical biological treatment
(MBT) plant, in the UK.
The biogas yield using the semi-continuous reactor was determined to be between 300
and 410 mL/gVS with average methane content of 51% and average volatile solid
destruction of 70%. During the batch system, the biogas yield was determined to be
between 200 and 220 mL/gVS, with average methane content of 54% and volatile
destruction of 70%, at the end of the digestion trial.
Heavy metal analysis indicated accumulation of some elements during the treatment;
however, final values were lower than risk limits. Microbial community profile through
phospholipid fatty acids (PLFA) analysis was investigated to determine structure shifts
between different treatment and over time; although no statistical significance (p>0.05)
was detected, PLFA peaks presented a shift in the community profile when comparing two
different treatment applied. The community structure was demonstrated to be stable and
resilient, able to cope with different parameters and stress.
The results of this study indicate that mixed municipal solid waste is favourable to be
treated in anaerobic digestion plants with mechanical biological treatment (MBT) with
regards to its biogas yield and waste size reduction through volatile solid destruction
A decision support tool for landfill methane generation
Get PDFThis paper focuses on providing a decision support tool (DST) to enhance
methane generation at individual landfill sites. To date there is no decision
support tool (DST) available to provide landfill decision makers with clear and
simplified information for decision makers to understand what is happening within
a landfill site, to assess its performance and to be aware of potential remedies to
any issues. The current lack in understanding stems from the complexity of the
landfill waste degradation process. Two scoring sets for landfill gas production
performance are calculated with the tool including (1) methane output score
which measures the deviation of the actual methane output rate at each site
which the prediction generated by the first order decay model LandGEM; and (2)
landfill gas indicators’ score which measures the deviation of the landfill gas
indicators from their individual ideal ranges for optimal methane generation
conditions. Landfill gas indicators selected include moisture content,
temperature, alkalinity, pH, BOD, COD, BOD/COD ratio, ammonia, chloride, iron
and zinc. A total landfill gas indicator score is also provided using multi-criteria
analysis to calculate the sum of weighted scores for each indicator. The weights
for each indicator are calculated using the analytical hierarchical process. The
tool is tested against five scenarios for landfill sites with a range of good, average
and poor landfill methane generation in one year, 2012. An interpretation of the
results is given for each scenario and recommendations are highlighted for
methane output rate enhancement. The scenarios used clearly illustrated how
the tool can be easily used by landfill operators to enhance their understanding
of methane generation at a site-specific level. The tool assists the landfill operator
to track landfill methane generation over time, compare and rank sites and
identify problems areas within a landfill site
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