The denatured state of N-PGK is compact and predominantly disordered

The Organisation of the structure present in the chemically denatured N-terminal domain of phosphoglycerate kinase (N-PGK) has been determined by paramagnetic relaxation enhancements (PREs) to define the conformational landscape accessible to the domain. Below 2.0 M guanidine hydrochloride (GuHCl), a species of N-PGK (denoted I-b) is detected, distinct from those previously characterised by kinetic experiments [folded (F), kinetic intermediate (I-k) and denatured (D)]. The transition to I-b is never completed at equilibrium, because F predominates below 1.0 M GuHCl. Therefore, the ability of PREs to report on transient or low population species has been exploited to characterise I-b. Five single cysteine variants of N-PGK were labelled with the nitroxide electron spin-label MTSL [(1-oxyl-2,2,5,5-tetramethyl-3-pyrroline-3-methyl)methanesulfonate] and the denaturant dependences of the relaxation properties of the amide NMR signals between 1.2 and 3.6 M GuHCl were determined. Significant PREs for I-b were obtained, but these were distributed almost uniformly throughout the sequence. Furthermore, the PREs indicate that no specific short tertiary contacts persist. The data indicate a collapsed state with no coherent three-dimensional structure, but with a restricted radius beyond which the protein chain rarely reaches. The NMR characteristics Of I-b indicate that it forms from the fully denatured state within 100 mu s, and therefore a rapid collapse is the initial stage of folding of N-PGK from its chemically denatured state. By extrapolation, I-b is the predominant form of the denatured state under native conditions, and the non-specifically collapsed structure implies that many non-native contacts and chain reversals form early in protein folding and must be broken prior to attaining the native state topology. (C) 2008 Elsevier Ltd. All rights reserved

Friction at the tennis shoe-court interface: how biomechanically informed lab-based testing can enhance understanding

This paper presents some of the methodology, observations and findings from a 30-month study, aiming to improve the understanding of tennis shoe-court interactions and the biomechanical implications of changes in friction between the shoe and surface. A detailed programme of biomechanical player testing on different court surfaces provided the boundary conditions with which to develop a lab-based rig capable of simulating the key aspects of shoe-surface interaction that are required for acceptable performance (e.g. push-off to accelerate) within expected levels of consistency (e.g. for a controlled slide). Large- scale parametric testing could then be carried out for a variety of surface types and components under a range of loading conditions, without the risk of injury to human participants. Two case studies are described to demonstrate the value of a combined approach of biomechanical field testing and lab-based rigs that simulate shoe-court interactions. These include a study that compared different artificial clay court designs; and a study that examined the effect of different acrylic hard court parameters on friction and the tribological mechanisms that explain the observed interactio

A modern approach to the Heckel Equation: The effect of compaction pressure on the yield pressure of ibuprofen and its sodium salt

Despite being heavily criticised in the literature the most widely used and accepted compaction equation is the Heckel equation proposed by Heckel in 1961. Its presence in literature for 55 years is due to the ease in which it can distinguish between plastic and brittle materials. Achieving the correct balance of plastic and brittle materials in a formulation is critical to ensure adequate tablet strength is achieved therefore classifying materials using the Heckel equation is attractive. Despite the importance of this understanding, especially in the design and manufacture of direct compression formulations, there are no set analytical testing standards or materials classification guidelines. Instead many workers have attempted to develop techniques for the measurement and classification of a materials deformation but there is still confusion and contradiction present in this field. In this study we repot on report the effect of compaction pressure on the yield pressure of ibuprofen and its sodium salt. Ibuprofen and its sodium salt were selected as models for study due to the availability of comparative literature yield pressure values. The reported variation in yield pressure can be significant e.g, ibuprofen which has literature values of 21-1139 MPa. This study proposes an approach to determine yield pressure from the Heckel equation using a linear regression method. The full linear regression methodology utilised is described and is used to report the yield pressure of ibuprofen and its sodium salt dihydrate. This technique reveals the most representative compaction pressure in order to derive yield pressure to be 121 MPa. The yield pressure of ibuprofen and its sodium salt have been shown to increase with increasing compaction pressure. The reported values lie between 52-78 MPa for ibuprofen and 48-75 MPa for ibuprofen sodium dihydrate. The slightly lower reported yield pressure values for ibuprofen sodium suggest increased plasticity which could be attributed to the water contained within the structure acting as a plasticiser

Improving the performance of soccer boots on artificial and natural soccer surfaces

AbstractAn improved understanding of studded shoe-surface interactions is needed to optimise athletic performance in soccer. Soccer studs are required to penetrate the playing surface and provide traction to a soccer player. The translational traction at the shoesurface interface is important for soccer players performing dynamic accelerating movements. A study has been carried out to evaluate the performance of studded footwear on a natural surface and a third generation artificial surface. A mechanical traction test device was used to quantify the performance characteristics of soccer studs in terms of penetration and traction for both surfaces. Results found from testing an existing soccer stud were used as benchmark values in order to evaluate the performance of five other soccer studs. The effects of the surface properties and stud geometry on stud penetration and traction are discussed

Large Kinetic Power in FRII Radio Jets

We investigate the total kinetic powers (L_{j}) and ages (t_{age}) of powerful jets of four FR II radio sources (Cygnus A, 3C 223, 3C 284, and 3C 219) by the detail comparison of the dynamical model of expanding cocoons with observed ones. It is found that these sources have quite large kinetic powers with the ratio of L_{j} to the Eddington luminosity (L_{Edd}) resides in $0.02 <L_{j}/L_{Edd} <10$. Reflecting the large kinetic powers, we also find that the total energy stored in the cocoon (E_{c}) exceed the energy derived from the minimum energy condition (E_{min}): $2< E_{c}/E_{min} <160$. This implies that a large amount of kinetic power is carried by invisible components such as thermal leptons (electron and positron) and/or protons.Comment: 5 pages, accepted for publication in Astrophysics and Space Scienc

From “where” and “when” to “what” and “why”: archival tags for monitoring “complex” behaviours in fish.

Understanding the movements (“where” and “when”) and behaviour (“what” and, hopefully, “why”) of individuals and populations is key to answering fundamental questions in fish ecology. The use of archival tags in telemetry studies of marine fish have, by and large, involved recording “simple” measurements of variables such as pressure (giving depth), temperature and light over extended timescales. These have then been used to provide information about location and movement of individuals. However, our understanding of more complex behaviours (i.e. what fish are doing as different from spatial movements) has usually been inferred from movement data because it has not been possible to record directly specific behavioural events such as feeding or spawning. This is because the events are usually infrequent, irregular and often quite brief and so not amenable to a technology based on taking regular but infrequent records of continuously available variables. The recent implementation of new sensors (e.g. physical movement, tri-axial accelerometers), rapid (< 30 Hz) sampling capabilities, enhanced memory and more complex data capture protocols has lead to the development of archival tags that can be used to detect and record complex behaviours such as feeding and spawning. We describe recent developments with archival tags and their use to monitor feeding and spawning in fish together with the application of tri-axial accelerometry that can be used to quantify behaviour and metabolic rate. These can then be used to assess the cost of behaviours with a view to understanding how appropriate they are as responses to environmental variability. Keywords: telemetry, behaviour, data storage ta

Magnetic fluctuations and spin freezing in nonsuperconducting LiFeAs derivatives

We present detailed magnetometry and muon-spin rotation data on polycrystalline samples of overdoped, nonsuperconducting LiFe1−xNixAs (x = 0.1,0.2) and Li1−yFe1+yAs (0 y 0.04) as well as superconducting LiFeAs.While LiFe1−xNixAs exhibits weak antiferromagnetic fluctuations down to 1.5 K,Li1−yFe1+yAs samples, which have a much smaller deviation from the 1 : 1 : 1 stoichiometry, show a crossover from ferromagnetic to antiferromagnetic fluctuations on cooling and a freezing of dynamically fluctuating moments at low temperatures. We do not find any signatures of time-reversal symmetry breaking in stoichiometric LiFeAs that would support recent predictions of triplet pairing

Bereavement care for ethnic minority communities : a systematic review of access to, models of, outcomes from, and satisfaction with, service provision

Objectives To review and synthesize the existing evidence on bereavement care, within the United Kingdom (UK), for ethnic minority communities in terms of barriers and facilitators to access; models of care; outcomes from, and satisfaction with, service provision. Design A systematic review adopting a framework synthesis approach was conducted. An electronic search of the literature was undertaken in MEDLINE, Embase, PsycINFO, Social Work Abstract and CINAHL via EBSCO, Global Health, Cochrane library, the Trip database and ProQuest between 1995 and 2020. Search terms included bereavement care, ethnic minority populations and the UK setting. Results From 3,185 initial records, following screening for eligibility, and full-text review of 164 articles, seven studies were identified. There was no research literature outlining the role of family, friends and existing networks; and a real absence of evidence about outcomes and levels of satisfaction for those from an ethnic minority background who receive bereavement care. From the limited literature, the overarching theme for barriers to bereavement care was ‘unfamiliarity and irregularities’. Four identified subthemes were ‘lack of awareness’; ‘variability in support’; ‘type and format of support’; and ‘culturally specific beliefs’. The overarching theme for facilitators for bereavement care was ‘accessibility’ with the two subthemes being ‘readily available information’ and ‘inclusive approaches’. Three studies reported on examples of different models of care provision. Conclusions This review reveals a stark lack of evidence about bereavement care for ethnic minority populations. In particular, understanding more about the role of family, friends and existing support systems, alongside outcomes and satisfaction will begin to develop the evidence base underpinning current provision. Direct user-representation through proactive engagement and co-design approaches may begin to determine the most appropriate models and format of bereavement care for ethnic minority communities to inform service design and delivery