Recent publications in Physical Sciences
The majority of water utilities currently employ the in-lab tests of the grabbed samples to determine the free chlorine (FC) residual levels. Under certain circumstances, such approaches are inadequate to timely and accurately reflect the dynamically changed FC residual levels, leading to inappropriate dosages. This work reports a uniquely configured membrane-based colorimetric flow-injection system (MCFIS) capable of accurately and reliably online monitoring drinking water FC residual levels in a rapid (1−5 min per measurement) fashion. The embedded gas-permeable membrane makes MCFIS an interference-free FC monitoring system. The developed pre-calibration strategy avoids the need for on-going calibration. The accuracy of the conventional analytical principles is almost exclusively determined by the absolute analytical signal value of one measurement data point, and any errors from such a single-data point measurement will be directly transferred to the result, which induces uncertainties, hence, poor accuracy and reliability. Differing distinctively from such conventional analytical principles, MCFIS quantifies chlorine concentration based on N, N-diethyl-p-phenylenediamine – Cl2 colorimetric reaction-controlled membrane transport process that enables the determination of gaseous chlorine concentration according to multiple measurement data points to greatly enhance the accuracy and reliability. The inherent analytical features of this slope-based signal quantification principle, interference-free and on-going calibration-free empower MCFIS with an enormous superiority over other systems for online FC monitoring applications.
Zhou, Ming, Li, Tianling, Xing, Chao, Liu, Yang, and Zhao, Huijun (2021) Membrane-based portable colorimetric gaseous chlorine sensing probe. Analytical Chemistry. (In Press)
Highly toxic chlorine gas imposes serious health risks in the workplace. The ability to on-site, real-time monitoring of instantaneous and time-weighted average (TWA) chlorine gas concentrations in a simple, sensitive, accurate, and reliable manner would be highly beneficial to improve workplace health and safety. Here, we propose and experimentally validate a gaseous chlorine detection principle based on a N,N-diethyl-p-phenylenediamine sulfate salt/Cl2 colorimetric reaction-controlled membrane process to regulate the gaseous chlorine transport across a gas-permeable membrane that enables the establishment of a time-resolved analytical relationship to quantify chlorine concentration by multidata points with dramatically enhanced accuracy and reliability. A gas-permeable membrane-based portable colorimetric gaseous chlorine sensing probe (MCSP) was designed and fabricated. The MCSP embedded the proposed analytical principle that is capable of real-time continuous monitoring of the instantaneous and TWA chlorine gas concentrations within an analytical range of 0.009–2.058 mg L–1 without the need for on-going calibration, which could be a useful analytical tool for managing the toxic chlorine gas-imposed health risks in workplaces.
Gelin, Maxim F., and Kosov, Daniel S. (2021) A model for dynamical solvent control of molecular junction electronic properties. Journal of Chemical Physics, 154 (4). 044107.
Experimental measurements of electron transport properties of molecular junctions are often performed in solvents. Solvent–molecule coupling and physical properties of the solvent can be used as the external stimulus to control the electric current through a molecule. In this paper, we propose a model that includes dynamical effects of solvent–molecule interaction in non-equilibrium Green’s function calculations of the electric current. The solvent is considered as a macroscopic dipole moment that reorients stochastically and interacts with the electrons tunneling through the molecular junction. The Keldysh–Kadanoff–Baym equations for electronic Green’s functions are solved in the time domain with subsequent averaging over random realizations of rotational variables using the Furutsu–Novikov method for the exact closure of infinite hierarchy of stochastic correlation functions. The developed theory requires the use of wideband approximation as well as classical treatment of solvent degrees of freedom. The theory is applied to a model molecular junction. It is demonstrated that not only electrostatic interaction between molecular junction and solvent but also solvent viscosity can be used to control electrical properties of the junction. Alignment of the rotating dipole moment breaks the particle–hole symmetry of the transmission favoring either hole or electron transport channels depending upon the aligning potential.
Housley, David M., Pinyon, Jeremy L., Jonquieres, Georg von, Perera, Chamini J., Smout, Michael, Liddell, Michael J., Jennings, Ernest A., Wilson, David, and Housley, Gary D. (2020) Australian scorpion Hormurus waigiensis venom fractions show broad bioactivity through modulation of bio-impedance and cytosolic calcium. Biomolecules, 10 (4). 617.
Scorpion venoms are a rich source of bioactive molecules, but characterisation of toxin peptides affecting cytosolic Ca2+, central to cell signalling and cell death, is limited. We undertook a functional screening of the venom of the Australian scorpion Hormurus waigiensis to determine the breadth of Ca2+ mobilisation. A human embryonic kidney (HEK293) cell line stably expressing the genetically encoded Ca2+ reporter GCaMP5G and the rabbit type 1 ryanodine receptor (RyR1) was developed as a biosensor. Size-exclusion Fast Protein Liquid Chromatography separated the venom into 53 fractions, constituting 12 chromatographic peaks. Liquid chromatography mass spectroscopy identified 182 distinct molecules with 3 to 63 components per peak. The molecular weights varied from 258 Da—13.6 kDa, with 53% under 1 kDa. The majority of the venom chromatographic peaks (tested as six venom pools) were found to reversibly modulate cell monolayer bioimpedance, detected using the xCELLigence platform (ACEA Biosciences). Confocal Ca2+ imaging showed 9/14 peak samples, with molecules spanning the molecular size range, increased cytosolic Ca2+ mobilization. H. waigiensis venom Ca2+ activity was correlated with changes in bio-impedance, reflecting multi-modal toxin actions on cell physiology across the venom proteome.
Winter, Sara, Gordon, Susan, Brice, Sara, Lindsay, Daniel, and Barrs, Sue (2020) Overuse injuries in runners of different abilities — a one-year prospective study. Research in Sports Medicine. (In Press)
The aim of this prospective study was to investigate differences in participant characteristics, previous injury, running dynamics during a long-distance run, and training between injured and uninjured runners in runners of different abilities. Center-of-mass acceleration data were collected during a long-distance overground run. Runners were then divided into four groups (elite, advanced, intermediate and slow) based on their finishing time. Participants completed training diaries and were monitored for 1 year. Seventy-six runners completed the prospective study with 39 (51.3%) sustaining a running injury (44% elite, 42% advanced, 54% intermediate, 59% slow). Differences between injured and uninjured runners within each group related to injury included: (1) elite injured runners ran with longer contact times and (2) more slow injured runners reported an injury in previous year, were heavier, had higher body mass and body mass index, ran with lower step frequencies, and ran a greater weekly distance. Advanced injured runners exhibited fatigue changes in step regularity and peak braking during the run that may be related to injury. These findings suggest that runners of different abilities may have different factors related to injury however due to the small sample sizes in the groups this needs to be explored further.
Das, Sourav, Subba Rao, Tata, and Boshnakov, Georgi N. (2020) An asymptotically unbiased weighted least squares estimation criterion for parametric variograms of second order stationary geostatistical processes. Communications in Statistics: simulation and computation, 49 (7). pp. 1839-1854.
In many fields of science dealing with geostatistical data, the weighted least squares proposed by Cressie Cressie (1985 Cressie, N. 1985. Fitting variogram models by weighted least squares (1985) remains a popular choice for variogram estimation. Simplicity, ease of implementation and non-parametric nature are its principle advantages. It also avoids the heavy computational burden of Generalized least squares. But that comes at the cost of loss of information due to the use of a diagonal weight matrix. Besides, the parameter dependent weight matrix makes the estimating equations biased. In this paper we propose two alternative weight matrices which do not depend on the parameters. We show that one of the weight matrices gives parameter estimates with lower asymptotic variance and also has asymptotically unbiased estimating equations. The observations are validated using simulation and real data.
Brice, Sara M., Phillips, Elissa J., Millett, Emma L., Hunter, Adam, and Philippa, Bronson (2020) Comparing inertial measurement units and marker-based biomechanical models during dynamic rotation of the torso. European Journal of Sport Science, 20 (6). pp. 767-775.
Inertial measurement units (IMUs) enable human movements to be captured in the field and are being used increasingly in high performance sport. One key metric that can be derived from IMUs are relative angles of body segments which are important for monitoring form in many sports. The purpose of this study was to a) examine the validity of relative angles derived from IMUs placed on the torso and pelvis; and b) determine optimal positioning for torso mounted sensors such that the IMU relative angles match closely with gold standard torso-pelvis and thorax-pelvis relative angle data derived from an optoelectronic camera system. Seventeen adult participants undertook a variety of motion tasks. Four IMUs were positioned on the torso and one was positioned on the pelvis between the posterior superior iliac spines. Reflective markers were positioned around each IMU and over torso and pelvis landmarks. Results showed that the IMUs are valid with the root mean square errors expressed as a percentage of the angle range (RMSE%) ranging between 1% and 7%. Comparison between the IMU relative angles and the torso-pelvis and thorax-pelvis relative angles showed there were moderate to large differences with RMSE% values ranging between 4% and 57%. IMUs are highly accurate at measuring orientation data; however, further work is needed to optimize positioning and modelling approaches so IMU relative angles align more closely with relative angles derived using traditional motion capture methods.
Lei, Peng, Zhou, Ying, Zhu, Ruiqi, Liu, Yang, Dong, Chuan, and Shuang, Shaomin (2020) Novel strategy of electrochemical analysis of DNA bases with enhanced performance based on copper−nickel nanosphere decorated N,B−doped reduced graphene oxide. Biosensors and Bioelectronics, 147. 111735.
Design of suitable nanocomposites with tailored structures was significant in the fabrication of effective and reliable electrochemical sensors. Herein, the copper−nickel@nitrogen, boron−doped reduced graphene oxide (Cu–Ni@N,B−rGO) was successfully synthesized, which exhibited superior electrocatalytic performance towards guanine (G) and adenine (A) oxidation. The Cu–Ni NPs were sequentially decorated on N,B−rGO substrate via an environmentally friendly reduction strategy, which utilized glucose as reducer and stabilizing agent. The nanocomposites with large specific surface area, remarkable conductivity and high catalytic activity showed prominent synergistic effect owning to the uniform dispersion of Cu–Ni NPs on the surface of N,B−rGO. When applied to analysis of G and A using DPV, the wide linear ranges of 1.0–160.0 μM and 1.0–120.0 μM with the determination limits of 0.118 μM and 0.134 μM were obtained, respectively. The sensor was successfully applied to the detection of G and A in calf−thymus DNA with G/A ratio of 0.80. The facile preparation process and attractive sensing properties of the Cu–Ni@N,B−rGO nanocomposites made it a promising candidate for the development of advanced electrochemical sensor.
Brice, Sara M., Doma, Kenji, Harland, Liam, and Spratford, Wayne (2020) Impact of performing heavy-loaded barbell back squats to volitional failure on lower limb and lumbo-pelvis mechanics in skilled lifters. Journal of Sports Sciences, 38 (1). pp. 100-105.
A common practice in resistance training is to perform sets of exercises at, or close to failure, which can alter movement dynamics. This study examined ankle, knee, hip, and lumbo-pelvis dynamics during the barbell back squat under a moderate-heavy load (80% of 1 repetition maximum (1RM)) when performed to failure. Eleven resistance trained males performed three sets to volitional failure. Sagittal plane movement dynamics at the ankle, knee, hip, and lumbo-pelvis were examined; specifically, joint moments, joint angles, joint angular velocity, and joint power. The second repetition of the first set and the final repetition of the third set were compared. Results showed that while the joint movements slowed (p < 0.05), the joint ranges of motion were not altered There were significant changes in most mean joint moments (p < 0.05), indicating altered joint loading. The knee moment decreased while the hip and lumbo-pelvis moments underwent compensatory increases. At the knee and hip, there were significant decreases (p < 0.05) in concentric power output (p < 0.05). Whilst performing multiple sets to failure altered some joint kinetics, the comparable findings in joint range of motion suggest that technique was not altered. Therefore, skilled individuals appear to maintain technique when performing to failure.
Zhu, Chengxi, Liu, Dong, Li, Yuye, Shen, Xiuli, Ma, Shuai, Liu, Yang, and You, Tianyan (2020) Ratiometric electrochemical aptasensor for ultrasensitive detection of Ochratoxin A based on a dual signal amplification strategy: engineering the binding of methylene blue to DNA. Biosensors and Bioelectronics, 150. 11814.
A novel ratiometric electrochemical aptasensor was developed for Ochratoxin A (OTA) detection based on the binding of methylene blue (MB) to DNA with a dual signal amplification strategy. The formation of dsDNA structures between ferrocene-labeled complementary DNA (Fc-cDNA), the OTA aptamer, and complementary helper DNA (hDNA) caused Fc away from the electrode, and allowed dsDNA to bind with a certain amount of MB. Here, a small oxidation current of Fc (IFc) and a large oxidation current of MB (IMB) were obtained. In the presence of OTA, its specific recognition with the aptamer induced the release of aptamer and hDNA from the electrode and subsequently the formation of hairpin structure for cDNA, which caused Fc close to the electrode and a weaker binding ability with MB. Then, an increased IFc and a decreased IMB were obtained. Based on this principle, OTA could be accurately quantified by measuring the ratiometric signal of IFc/IMB. Herein, the dual signal amplification strategy of the introduction of hDNA and the binding with MB after the OTA recognition was exploited to amplify the response signal. The obtained aptasensor showed a linear detection range from 10 pg mL1 to 10 ng mL1 and a detection limit of 3.3 pg mL1. The aptasensor was successfully applied to determine OTA in wheat, and the results were validated through HPLC-MS. Furthermore, by changing the target aptamers, this strategy could be universally used for the determination of various mycotoxins, showing prom-ising potential applications for mycotoxins monitoring in agricultural products and foods.
Li, Lin, Shi, Lihong, Jia, Jing, Jiao, Yuan, Gao, Yifang, Liu, Yang, Dong, Chuan, and Shuang, Shaomin (2020) “On-off-on” detection of Fe³⁺ and F⁻, biological imaging, and its logic gate operation based on excitation-independent blue-fluorescent carbon dots. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 227. 117716.
A fluorescent nanoprobe based on carbon dots (CDs) has been facilely synthesized by a one-step hydrothermal pyrolysis of salicylic acid and utilized for the sequential detection of Fe3+ and F− in vitro. The fluorescence of CDs can be extinguished dramatically by Fe3+ based on static quenching and subsequently recovery upon addition of F− due to the formation of stabler FeF3. The probe exhibits high selectivity and sensitivity toward Fe3+ and F− with a good linearity in the range of 10–300 μM and 0.1–200 μM, respectively, and a low detection limit of 52 nM and 8.5 nM, respectively. More importantly, as-prepared CDs with exceedingly fluorescence stability, negligible toxicity and superior biocompatibility have been expanded for detection Fe3+ and F− in living cell and Escherichia coli. Furthermore, an “AND” logic gate based on as-obtained CDs has been constructed.
Shen, Xiuli, Liu, Dong, Zhu, Chengxi, Li, Yuye, Liu, Yang, and You, Tianyan (2020) Photoelectrochemical and electrochemical ratiometric aptasensing: a case study of streptomycin. Electrochemistry Communications, 110. 106637.
There has been much interest in constructing ratiometric sensors using different sensing techniques because of their synergistic effect, although the simultaneous collection of the signals is challenging. Herein, we propose a ratiometric aptasensing strategy based on the dual-detection model with a photoelectrochemical (PEC) “signalon” and an electrochemical (EC) “signal-off”. As a proof-of-concept study, CdTe quantum dots (CdTe QDs) and a methylene blue-labeled aptamer (MB-Apt) were used to generate PEC and EC signals in the sensing system. The target-induced conformational change of MB-Apt pushed MB away from the electrode, thereby decreasing the EC signal; at the same time, the reduced steric hindrance favored the restoration of the PEC signal from the CdTe QDs. Thus, this PEC-EC strategy can achieve the PEC “signal-on” and EC “signal-off” states simultaneously, as well as allowing quantitative analysis of the target based on the ratio of the current intensities. As a model application, an aptasensor fabricated for streptomycin detection showed a wide linear range from 0.03 to 100 μM with a detection limit of 10 nM (S/N = 3). The proposed sensing platform displayed superior analytical properties compared with methods based on PEC or EC alone. Our work provides an efficient dual-detection modelbased ratiometric strategy for advanced analysis, and paves the way to the simultaneous acquisition of signals.
Li, Yuye, Liu, Dong, Zhu, Chengxi, Shen, Xiuli, Liu, Yang, and You, Tianyan (2020) Sensitivity programmable ratiometric electrochemical aptasensor based on signal engineering for the detection of aflatoxin B1 in peanut. Journal of Hazardous Materials, 387. 122001.
Accurately monitoring of aflatoxin B1 (AFB1), the most hazardous mycotoxin in agricultural products, is essential for the public health, but various testing demands (e.g. detection range, sensitivity) for different samples can be challenging for sensors. Here, we developed a sensitivity-programmable ratiometric electrochemical aptasensor for AFB1 analysis in peanut. Thionine functionalized reduced graphene oxide (THI-rGO) served as reference signal generator, ferrocene-labelled aptamer (Fc-apt) output the response signal. During analysis, the formation of Fc-apt-AFB1 complex led to its stripping from the electrode and faded the current intensity of Fc (IFc), while the current intensity of THI (ITHI) was enhanced. And ratiometric detection of AFB1 was achieved by using the current intensity ratio (ITHI/IFc) as quantitative signal. Compared with ratiometric strategies that highly rely on the labelled aptamers, the proposed strategy could regulate the value of ITHI/IFc by changing the modification of Fc-apt. And the detection sensitivity was found to be closely related to ITHI/IFc. Under the optimal conditions, the fabricated aptasensor with a dynamic range from 0.05–20 ng mL−1 and a detection limit of 0.016 ng mL−1 for AFB1 analysis. Besides, it exhibited excellent selectivity, reliability and reproducibility. The proposed sensitivity-programmable biosensor can be applied to detect various aptamer-recognized mycotoxins in agricultural sensing.
Deka, Rajesh, Junk, Peter C., Turner, David R., Deacon, Glen B., and Singh, Harkesh B. (2020) An insight into the redox activity of Ru and Os complexes of the N,N′-bis(2-pyridyl)benzene-1,2-diamine ligand: structural, electrochemical and electronic structure analysis by density functional theory calculations. Inorganica Chimica Acta, 499. 119193.
The synthesis of Ru and Os complexes of the ligand, N,N′-bis(2-pyridyl)benzene-1,2-diamine namely, [Ru-¹¹¹(acac)₂(Py-bqdi)], (9), (Ru-¹¹(Ph-trpy)(Py-bqdi)Cl], (10) and (Os-¹¹(bpy)₂(Py-bqdi)](ClO₄), (ClO₄) [where Py-bqdi = N,N′-dipyridyl-o-benzoquinonediimine, acac = 2,4-pentanedionate, Ph-trpy = 4'-phenyl-2,2′:6′,2″ -terpyridine, bpy = 2,2′-bipyridine] is reported. The molecular structures of complexes 9-ClO₄ are authenticated by single crystal X-ray diffraction studies. The electronic structural properties of the complexes, in particular, the accessible oxidized/reduced forms of the complexes, are examined by using an array of analytical techniques (magnetic resonance, UV-Vis-NIR spectroscopy and electrochemistry). Comprehensive Density Functional Theory (DFT) calculations have also been carried out to provide additional support to the experimental work.
Aldabbagh, Areej K., Junk, Peter C., and Wang, Jun (2020) Syntheses and molecular structures of heteroleptic and homoleptic antimony(iii) tetrafluorophenylethylenediamidate complexes. Australian Journal of Chemistry, 73. pp. 504-510.
A series of hetero- and homoleptic organoamidoantimony(iii) complexes of the type [SbLMe3-nCln] (n = 2, 1, 0) (HLMe = p-HC6F4NH(CH2)2NMe2) incorporating a bulky amido fluorinated ligand tethered with an amino pendant arm, have been successfully synthesised and fully characterised as monomers in the solid state. [Sb(p-HC6F4NC2H4NMe2)Cl2] (1), [Sb(p-HC6F4NC2H4NMe2)2Cl] (2), and [Sb(p-HC6F4NC2H4NMe2)3] (3) were isolated by metathesis reactions involving different stoichiometric ratios between SbCl3 and Li(p-HC6F4N(CH2)2NMe2) (LiLMe) in non-coordinating solvents, while [Sb(p-HC6F4NC2H4NMe2)Cl2] (1) was also synthesised by the direct reaction between SbCl3 and HLMe in THF providing an interesting alternative pathway to access these types of compounds.
Winter, Sara C., Gordon, Susan, Brice, Sara M., Lindsay, Daniel, and Barrs, Sue (2020) A multifactorial approach to overuse running injuries: a 1-year prospective study. Sports Health. (In Press)
Background: Because of the complex and multifaceted nature of running injuries, a multifactorial approach when investigating running injuries is required. Hypothesis: Compared with uninjured runners, injured runners would exhibit different running biomechanics, display more fatigue changes, and would run a greater weekly running volume; more injured runners would also report having a previous injury. Study Design: Prospective cohort study. Level of Evidence: Level 4. Methods: At commencement of the study, data were collected on demographics, anthropometrics, training history, previous injury history, and center-of-mass accelerations during a long-distance overground run. Participants completed weekly training diaries and were monitored for 1 year for an injury. Results: A total of 76 runners completed the study, with 39 (22 male; 17 female) reporting an injury. Compared with male uninjured runners, male injured runners were heavier and ran a greater weekly distance. Male runners (injured and uninjured) exhibited increases in mediolateral center-of-mass accelerations during the run. Compared with female uninjured runners, female injured runners were heavier, ran with longer flight times and lower step frequencies, and more of them had reported an injury in the previous year and had increased speed training in the weeks prior to injury. Over 60% of male injured runners and over 50% of female injured runners had increased their weekly running distance by >30% between consecutive weeks at least once in the 4 weeks prior to injury. Conclusion: Factors that may be related to injury for male runners include being heavier, running a greater weekly distance, and exhibiting fatigue changes in mediolateral center-of-mass accelerations. Factors that may be related to injury for female runners include being heavier, having an injury in the previous year, running with longer flight times and lower step frequencies, and increasing speed training prior to injury. Increases in weekly running distance in 1 consecutive week (particularly >30%) needs to be monitored in training, and this along with the other factors found may have contributed to injury development. Clinical Relevance: This study found that multiple factors are related to running injuries and that some factors are sex specific. The findings can aid in injury prevention and management.
Deka, Rajesh, Sarkar, Arup, Butcher, Ray J., Junk, Peter C., Turner, David R., Deacon, Glen B., and Singh, Harkesh B. (2020) Isolation of homoleptic dicationic tellurium and monocationic bismuth analogues of non-N-heterocyclic carbene derivatives. Organometallics, 39 (2). pp. 334-343.
The first examples of Te analogues of non-N-heterocyclic carbene (non-NHC) derivatives, [(ppy)₂Te]·2ClO₄, ·2ClO₄, and [(ppy)₂Te]·2OTf, ·2OTf [where ppy = 2-(2'pyridyl)phenyl and Tf = O₂SCF₃] are reported by the metathesis reaction of diorganoiodotelluronium(IV) cation, [(ppy)₂TeI]·I₃, ·I₃, with AgClO₄ and AgOTf, respectively. The metathesis reaction of ppyTeCl₃, 6, with an excess of AgClO₄ resulted in the isolation of [ppyTe(μ-O)]₂·2ClO₄, ·2ClO₄. The reaction of triorganotelluronium(IV) cation [(ppy)₃Te]·Br, Br, with K₂PdCl₄ afforded [(ppy)₂TeCl]·[(ppy)PdCl₂], 11. The generality of the "ppy" group on stabilizing other main-group non-NHC analogues has been further established by synthesizing the second example of a Bi analogue of a non-NHC derivative, namely, bismuthenium ion, [(ppy)₂Bi]·Cl, ·Cl, using the same aryl group. All of the synthesized compounds are unambiguously authenticated by single-crystal X-ray diffraction studies. DFT calculations [natural bond orbital (NBO), atoms in molecules (AIM), and electron localization function (ELF)] indicate that the stability of the non-NHC carbenoids relies on the a-hole participation of the Te/Bi atom with the strong intramolecular coordination ability of the pyridyl N atom of the aryl substituent.
Sexton, Justin, Everingham, Yvette, Donald, David, Staunton, Steve, and White, Ronald (2020) Investigating the identification of atypical sugarcane using NIR analysis of online mill data. Computers and Electronics in Agriculture, 168. 105111.
In any given season thousands of tonnes of sugarcane with atypically low quality can pass undocumented through Australian sugarcane mills. Sugarcane with atypically low quality can negatively impact mill processes and throw off grower payment calculations. Mill laboratory operators often observe a small subset (1 similar to 5%) of cane consignments that have an unusually low juice Pol (Pij; a measure of sucrose content) relative to juice brix (Bij; a measure of dissolved sugars), that can indicate deteriorated or contaminated cane. Many mills only test a small subset of cane in the laboratory, with the majority of consignments analysed using fast near infrared (NIR) spectroscopic techniques. This means the true extent of 'atypical! consignments cannot be identified. To address this limitation, this paper compares five modelling approaches: Linear discriminant analysis (LDA), partial least squares discriminant analysis (PLS-DA), random forest (RF), Artificial Neural Networks (ANN) and Support Vector Machines (SVM). Model performance was reported as the correct classification rate (CCR) of typical and atypical samples based on independent test sets. The best performance was achieved by PLS-DA (CCRtypical = 88.65% and CCRtypical = 88.75%), while ANN had the lowest performance (CCRatypical = 85.27% and CCRtypical = 83.66%). The methodology used in this paper could be used to identify atypical consignments allowing mills to track occurrences to farms and if necessary develop process control operations for atypical cane. Furthermore, the use of a relatively simple modelling technique such as PLS-DA means model updates can be made efficiently and with confidence as PLS is already well established within the industry.
Oelgemoeller, Michael, and Guthrie, Duncan (2020) Continuous-flow photochemistry made easy with Vapourtec’s photoreactor series. EPA Newsletters, 97. pp. 38-42.
In March 2014, Vapourtec launched its UV-150 photochemical reactor. Since its introduction, additional accessories and features have been continuously released, which have made this device family suitable for a wide range of photochemical applications. Subsequently, the systems have been rapidly adopted by the academic and industrial communities and have been featured in over 75 publications. The photoreactor series developed by Vapourtec Ltd has been successfully applied to a wide range of homogeneous and heterogeneous (gas-liquid, solid-liquid or gas-liquid-solid) photoreactions. Optimization of reaction conditions (e.g. concentrations, wavelengths, light power or temperature) is rapidly achieved using small reagent volumes. Scale-up is then simply conducted by continuous operation over longer periods of time using larger stock solutions of reagents. In contrast to other commercial flow devices that are based entirely on LED light-sources, the UV-150 module allows photochemical investigations in the important UVC- and UVB-ranges. The simple interlock design of the individual components also permits an easy modification of the reactor system based on experimental requirements. Likewise, the unique tandem option readily facilitates in-series photochemical-thermal operations in the same continuous-flow in a single compact device (‘telescoping’).
Nordborg, F. Mikaela, Jones, Ross J., Oelgemöller, Michael, and Negri, Andrew P. (2020) The effects of ultraviolet radiation and climate on oil toxicity to coral reef organisms – a review. Science of the Total Environment, 720. 137486.
Oil pollution remains a significant local threat to shallow tropical coral reef environments, but the environmental conditions typical of coral reefs are rarely considered in oil toxicity testing and risk assessments. Here we review the effects of three environmental co-factors on petroleum oil toxicity towards coral reef organisms, and show that the impacts of oil pollution on coral reef taxa can be exacerbated by environmental conditions commonly encountered in tropical reef environments. Shallow reefs are routinely exposed to high levels of ultraviolet radiation (UVR), which can substantially increase the toxicity of some oil components through phototoxicity. Exposure to UVR represents the most likely and harmful environmental co-factor reviewed here, leading to an average toxicity increase of 7.2-fold across all tests reviewed. The clear relevance of UVR co-exposure and its strong influence on tropical reef oil toxicity highlights the need to account for UVR as a standard practice in future oil toxicity studies. Indeed, quantifying the influence of UVR on toxic thresholds of oil to coral reef species is essential to develop credible oil spill risk models required for oil extraction developments, shipping management and spill responses in the tropics. The few studies available indicate that co-exposure to elevated temperature and low pH, both within the range of current daily and seasonal fluctuations and/or projected under continued climate change, can increase oil toxicity on average by 3.0- and 1.3-fold, respectively. While all three of the reviewed environmental co-factors have the potential to substantially increase the impacts of oil pollution in shallow reef environments, their simultaneous effects have not been investigated. Assessments of the combined effects of oil pollution, UVR, temperature and low pH will become increasingly important to identify realistic hazard thresholds suitable for future risk assessments over the coming century.
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