Operational characteristics of surge arresters within high voltage substations

Surge arresters form a critical component in the safe and reliable operation of electrical zone substations. Overvoltages resulting from a lightning strike pose the greatest risk of damage to substation equipment reaching peak values of over 100 times the nominal line voltage within microseconds. During such overvoltage events, the surge arrester limits the level of voltage that the equipment is subjected to, thus providing protection to very expensive, and specialised electrical infrastructure. Correct arrester specification is the first step in determining the type of surge arrester required for each installation. A second, but no less important step is determination of its physical location and connection method. The distance a surge arrester is located from equipment is a significant factor in its ability in protecting equipment. Through the undertaking of this detailed research project, optimum arrester location, connection methods and insulation co-ordination derived from software simulation will be compared to standard design principles utilised by Essential Energy (EE) and verified using equivalent circuit analysis

Constraining Respired Carbon Storage in the Eastern Tropical Pacific Over the Last 25 Thousand Years Using Benthic Foraminiferal Boron/Calcium Ratios

The storage of inorganic carbon in the deep Pacific Ocean is thought to play an important role in regulating both glacial-interglacial and millennial-scale atmospheric CO2 concentrations (Broecker and Barker 2007; Sigman et al., 2010). A recent study by Loveley et al. (2017) showed that sedimentary authigenic uranium (aU) concentrations, a proxy for suboxic bottom-water conditions, increased significantly in the Eastern Equatorial Pacific (EEP) during the Last Glacial Maximum (LGM, 18 kyr – 23 kyr). If this is correct, the low-oxygen, CO2-rich waters would also have a lower pH and a lower carbonate ion concentration ([CO32-]). Yu and Elderfield (2007) showed that the boron to calcium (B/Ca) ratio in the benthic foraminifera C. wuellerstorfi is a reliable proxy for reconstructing bottom water [CO32-]. Here I present new constraints on deep ocean carbon storage over the last 25 kyr in the EEP using new benthic foraminiferal B/Ca-[CO32-] reconstructions from four cores at a range of depths from within and outside the Panama Basin. These four new records all reveal lower glacial [CO32-], with the largest LGM-Holocene difference coming from core MV1014-02-17JC (17JC) (00°10.83’S, 85°52.00’W; 2.9 km water depth) inside the Panama Basin. New depth profiles of glacial carbon storage in the region show that respired CO2 storage outside the Panama Basin was relatively homogenous while inside the basin there was a gradient of increasing CO2 storage with depth from 2.2 km down to 2.9 km. A new sub-millennial scale record shows that during the last deglaciation (18 kyr - 11 kyr), waters inside the Panama Basin experienced two large increases in respired CO2 storage during Heinrich Stadial 1 and the Younger Dryas. Finally, intra-core proxy comparisons of 232Th (a dust flux proxy), excess barium (a paleoproductivity proxy), and aU from 17JC and MV1014-02-8JC (8JC) (6°14’N, 86°2’W; 2 km water depth) illustrate that two different mechanisms likely influenced CO2 storage in the region. For 8JC, a poorly ventilated Pacific wide water mass was likely the source for the lower glacial [CO32-] at its core location. While for 17JC, in addition to the previously noted poorly ventilated water mass influence, respired CO2 storage at this core location was further enhanced by millennial scale increases in export production. By sequestering carbon away from the atmosphere and surface ocean, deep waters in the Panama Basin and in the greater EEP region likely played an important role in lowering glacial atmospheric CO2

Exercise redox biochemistry:conceptual, methodological and technical recommendations

Exercise redox biochemistry is of considerable interest owing to its translational value in health and disease. However, unaddressed conceptual, methodological and technical issues complicate attempts to unravel how exercise alters redox homeostasis in health and disease. Conceptual issues relate to misunderstandings that arise when the chemical heterogeneity of redox biology is disregarded which often complicate attempts to use redox-active compounds and assess redox signalling. Further, that oxidised macromolecule adduct levels reflect formation and repair is seldom considered. Methodological and technical issues relate to the use of out-dated assays and/or inappropriate sample preparation techniques that confound biochemical redox analysis. After considering each of the aforementioned issues, we outline how each issue can be resolved and provide a unifying set of recommendations. We specifically recommend that investigators: consider chemical heterogeneity, use redox-active compounds judiciously, abandon flawed assays, carefully prepare samples and assay buffers, consider repair/metabolism, use multiple biomarkers to assess oxidative damage and redox signalling

Age- and activity-related differences in the abundance of Myosin essential and regulatory light chains in human muscle

Traditional methods for phenotyping skeletal muscle (e.g., immunohistochemistry) are labor-intensive and ill-suited to multixplex analysis, i.e., assays must be performed in a series. Addressing these concerns represents a largely unmet research need but more comprehensive parallel analysis of myofibrillar proteins could advance knowledge regarding age- and activity-dependent changes in human muscle. We report a label-free, semi-automated and time efficient LC-MS proteomic workflow for phenotyping the myofibrillar proteome. Application of this workflow in old and young as well as trained and untrained human skeletal muscle yielded several novel observations that were subsequently verified by multiple reaction monitoring (MRM).We report novel data demonstrating that human ageing is associated with lesser myosin light chain 1 content and greater myosin light chain 3 content, consistent with an age-related reduction in type II muscle fibers. We also disambiguate conflicting data regarding myosin regulatory light chain, revealing that age-related changes in this protein more closely reflect physical activity status than ageing per se. This finding reinforces the need to control for physical activity levels when investigating the natural process of ageing. Taken together, our data confirm and extend knowledge regarding age- and activity-related phenotypes. In addition, the MRM transitions described here provide a methodological platform that can be fine-tuned to suite multiple research needs and thus advance myofibrillar phenotyping

The basic chemistry of exercise-induced DNA oxidation:oxidative damage, redox signalling and their interplay

Acute exercise increases reactive oxygen and nitrogen species generation. This phenomenon is associated with two major outcomes: (1) redox signalling and (2) macromolecule damage. Mechanistic knowledge of how exercise-induced redox signalling and macromolecule damage are interlinked is limited. This review focuses on the interplay between exercise-induced redox signalling and DNA damage, using hydroxyl radical (·OH) and hydrogen peroxide (H2O2) as exemplars. It is postulated that the biological fate of H2O2 links the two processes and thus represents a bifurcation point between redox signalling and damage. Indeed, H2O2 can participate in two electron signalling reactions but its diffusion and chemical properties permit DNA oxidation following reaction with transition metals and ·OH generation. It is also considered that the sensing of DNA oxidation by repair proteins constitutes a non-canonical redox signalling mechanism. Further layers of interaction are provided by the redox regulation of DNA repair proteins and their capacity to modulate intracellular H2O2 levels. Overall, exercise-induced redox signalling and DNA damage may be interlinked to a greater extent than was previously thought but this requires further investigation

Similarity and structured representation in human and nonhuman apes

How we judge the similarity between objects in the world is connected ultimately to how we represent those objects. It has been argued extensively that object representations in humans are ‘structured’ in nature, meaning that both individual features and the relations between them can influence similarity. In contrast, popular models within comparative psychology assume that nonhuman species appreciate only surface-level, featural similarities. By applying psychological models of structural and featural similarity (from conjunctive feature models to Tversky's contrast model) to visual similarity judgements from adult humans, chimpanzees, and gorillas, we demonstrate a cross-species sensitivity to complex structural information, particularly for stimuli that combine colour and shape. These results shed new light on the representational complexity of nonhuman apes, and the fundamental limits of featural coding in explaining object representation and similarity, which emerge strikingly across both human and nonhuman species

Regioselective routes to tetrasubstituted aromatic compounds

Polysubstituted aromatics are highly desirable in medicinal chemistry for library generation and the tetrasubstituted aryl motif appears in many pharmaceuticals. Current methods to access 1,2,4,5- and 1,2,3,4- tetrasubstituted aromatics are problematic. Therefore new routes giving defined regiochemical outcomes with four different orthogonal functionalities were sought. This work took two directions; 1) the bromination and nitration of trisubstituted aryl MIDA boronates, and 2) the nitration of trisubstituted aryl bromides, both leading to the desired tetrasubstituted aromatics. MIDA boronates are boronic acids masked with N-methyliminodiacetic acid (MIDA). This allows for iterative palladium cross-coupling reactions. The first step in the work was developing a new rapid microwave-mediated method (5-15 min) towards MIDA boronates using ether poly-ethylene glycol 300, acetonitrile or dimethylformamide as a solvent. This methodology gave a library of over 20, mainly aryl or heteroaryl MIDAboronates.1,2 Trisubstituted aryl-MIDAboronates were then brominated or nitrated giving 6 novel tetrasubstituted aromatic compounds. The 3 new tetrasubstituted aryl-MIDAboronates bromides were then used in a selection of iterative Suzuki–Miyaura cross coupling reactions (SM) to show the potential uses of the compound in library generation. Three different bromo-fluorobenzaldehyde regioisomers were nitrated giving 3 different tetrasubstituted aromatics. These 3 compounds were then subjected to several different conditions to modify them i.e. nitro reduction, Sonogashira couplings, reductive aminations, Clauson-Kaas pyrrole synthesis. A number of tetrasubstituted anilines were reacted with 4-chloro-6,7-dimethoxyquinazoline to afford novel, potential kinase inhibitors. Publications: (1) Close, A. J.; Kemmitt, P.; Emmerson, M. K.; Spencer, J. Tetrahedron 2014, 70, 9125–9131. (2) Close, A. J.; Corden, V.; Spencer, J. Use of a camera to monitor reaction stirring and reagent dissolution during a reaction; a MIDA boronate library generation case study. http://www.cemmicrowave.co.uk/assets/cameramida-boronate---app-note.pdf (accessed Nov 15, 2015)

Influence of vitamin C and vitamin E on redox signalling:implications for exercise adaptations

The exogenous antioxidants vitamin C (ascorbate) and vitamin E (α-tocopherol) often blunt favourable cell signalling responses to exercise, suggesting that redox signalling contributes to exercise adaptations. Current theories posit that this antioxidant paradigm interferes with redox signalling by attenuating exercise-induced reactive oxygen species (ROS) and reactive nitrogen species (RNS) generation. The well-documented in vitro antioxidant actions of ascorbate and α-tocopherol and characterisation of the type and source of the ROS/RNS produced during exercise theoretically enables identification of the redox-dependent mechanism responsible for the blunting of favourable cell signalling responses to exercise. This review aimed to apply this reasoning to determine how the aforementioned antioxidants might attenuate exercise-induced ROS/RNS production. The principal outcomes of this analysis are (1) neither antioxidant is likely to attenuate nitric oxide signalling either directly (reaction with nitric oxide) or indirectly (reaction with derivatives, e.g. peroxynitrite) (2) neither antioxidant reacts appreciably with hydrogen peroxide, a key effector of redox signalling (3) ascorbate but not α-tocopherol has the capacity to attenuate exercise-induced superoxide generation and (4) alternate mechanisms, namely pro-oxidant side reactions and/or reduction of bioactive oxidised macromolecule adducts, are unlikely to interfere with exercise-induced redox signalling. Out of all the possibilities considered, ascorbate mediated suppression of superoxide generation with attendant implications for hydrogen peroxide signalling is arguably the most cogent explanation for blunting of favourable cell signalling responses to exercise. However, this mechanism is dependent on ascorbate accumulating at sites rich in NADPH oxidases, principal contributors to contraction mediated superoxide generation, and outcompeting nitric oxide and superoxide dismutase isoforms. The major conclusions of this review are: (1) direct evidence for interference of ascorbate and α-tocopherol with exercise-induced ROS/RNS production is lacking (2) theoretical analysis reveals that both antioxidants are unlikely to have a major impact on exercise-induced redox signalling and (3) it is worth considering alternate redox-independent mechanisms

Physical loading in professional soccer players:Implications for contemporary guidelines to encompass carbohydrate periodization

Despite more than four decades of research examining the physical demands of match-play, quantification of the customary training loads of adult male professional soccer players is comparatively recent. The training loads experienced by players during weekly micro-cycles are influenced by phase of season, player position, frequency of games, player starting status, player-specific training goals and club coaching philosophy. From a macronutrient perspective, the periodization of physical loading within (i.e., match versus training days) and between contrasting micro-cycles (e.g., 1, 2 or 3 games per week schedules) has implications for daily carbohydrate (CHO) requirements. Indeed, aside from the well-recognised role of muscle glycogen as the predominant energy source during match-play, it is now recognised that the glycogen granule may exert regulatory roles in activating or attenuating the molecular machinery that modulate skeletal muscle adaptations to training. With this in mind, the concept of CHO periodization is gaining in popularity, whereby CHO intake is adjusted day-by-day and meal-by-meal according to the fuelling demands and specific goals of the upcoming session. On this basis, the present paper provides a contemporary overview and theoretical framework for which to periodize CHO availability for the professional soccer player according to the “fuel for the work” paradigm.</p