Extended conjugated microporous polymers for photocatalytic hydrogen evolution from water

Conjugated microporous polymers (CMPs) have been used as photocatalysts for hydrogen production from water in the presence of a sacrificial electron donor. The relative importance of the linker geometry, the co-monomer linker length, and the degree of planarisation were studied with respect to the photocatalytic hydrogen evolution rate

Gating of TonB-dependent transporters by substrate-specific forced remodelling

Membrane proteins play vital roles in inside-out and outside-in signal transduction by responding to inputs that include mechanical stimuli. Mechanical gating may be mediated by the membrane or by protein(s) but evidence for the latter is scarce. Here we use force spectroscopy, protein engineering and bacterial growth assays to investigate the effects of force on TonB-TonB dependent transporter (TBDT) complexes of Gram-negative bacteria. We confirm the feasibility of protein-only mediated mechanical gating by demonstrating that the interaction between TonB and BtuB (a TBDT) is sufficiently strong under force to create a channel through the TBDT. In addition, by comparing the dimensions of the force-induced channel in BtuB and a second TBDT (FhuA) we show that the mechanical properties of the interaction are perfectly tuned to their function by inducing formation of a channel whose dimensions are tailored to the ligand

Employee commitment : the motivational role of senior management theory of action

The aim of this study is to explore the association between senior managementtheory-of-action and employee commitment.Field research uses quantitative and qualitative method and concentrates on onemedium sized UK based organisation for data collection and experimentation.However, the study examines two further organisations to assist validity andspecificity of findings.The written work is in six parts. Following an introductory chapter, chapter twocontains a literature survey covering organisational purpose and seniormanagement theory-of-action. Chapter three examines literature as to employeecommitment, and personal and organisational values. The fourth chapter describesmethod. Field work in chapter five provides results arising from quantitative andqualitative research. The concluding chapter considers the extent to whichfindings should be generalised, and offers conclusions and reflection.The study points to the following conclusions:Field research supports the notion that compared with more conventionalmotivation factors, senior management employee related action is stronglyassociated with employee commitment. This finding was found to beespecially prominent at lower hierarchical levels within the organisation.The adoption of what is termed conventional 'Model-One' theory-of-actionadversely affects employee commitment.It is suggested that senior management theory-of-action can inhibit orfacilitate the maintenance and growth of employee commitment.The work provides credence as to the importance and strength of associationbetween senior management theory-of-action and employee commitment, and offers a method by which the association can be tested

Climate change is an important predictor of extinction risk on macroevolutionary timescales

Anthropogenic climate change is increasing rapidly and already impacting biodiversity. Despite the importance for future projections, understanding of the underlying mechanisms by which climate mediates extinction remains limited. We present an integrated approach examining the role of intrinsic traits vs. extrinsic climate change in mediating extinction risk for marine invertebrates over the past 485 million years. We found that a combination of physiological traits and the magnitude of climate change are necessary to explain marine invertebrate extinction patterns. Our results suggest that taxa previously identified as extinction resistant may still succumb to extinction if the magnitude of climate change is great enough

Diel turbidity cycles in a headwater stream: evidence of nocturnal bioturbation?

Purpose: A small number of recent studies have linked daily cycles in stream turbidity to nocturnal bioturbation by aquatic fauna, principally crayfish, and demonstrated this process can significantly impact upon water quality under baseflow conditions. Adding to this limited body of research, we use high-resolution water quality monitoring data to investigate evidence of diel turbidity cycles in a lowland, headwater stream with a known signal crayfish (Pacifastacus leniusculus) population and explore a range of potential causal mechanisms. Materials and methods: Automatic bankside monitoring stations measured turbidity and other water quality parameters at 30-min resolution at three locations on the River Blackwater, Norfolk, UK during 2013. Specifically, we focused on two 20-day periods of baseflow conditions during January and April 2013 which displayed turbidity trends typical of winter and spring seasons, respectively. The turbidity time-series, which were smoothed with 6.5 hour Savitzky-Golay filters to highlight diel trends, were correlated against temperature, stage, dissolved oxygen and pH to assess the importance of abiotic influences on turbidity. Turbidity was also calibrated against suspended particulate matter (SPM) over a wide range of values via linear regression. Results and discussion: Pronounced diel turbidity cycles were found at two of the three sites under baseflow conditions during April. Spring night-time turbidity values consistently peaked between 21:00 and 04:00 with values increasing by ~10 nephelometric turbidity units (NTU) compared with the lowest recorded daytime values which occurred between 10:00 and 14:00. This translated into statistically significant increases in median midnight SPM concentration of up to 76% compared with midday, with night-time (18:00 – 05:30) SPM loads also up to 30% higher than that recorded during the daytime (06:00 – 17:30). Relating turbidity to other water quality parameters exhibiting diel cycles revealed there to be neither any correlation that might indicate a causal link, nor any obvious mechanistic connections to explain the temporal turbidity trends. Diel turbidity cycles were less prominent at all sites during the winter. Conclusions: Considering the seasonality and timing of elevated turbidity, visual observations of crayfish activity, and an absence of mechanistic connections with other water quality parameters, the results presented here are consistent with the hypothesis that nocturnal bioturbation is responsible for generating diel turbidity cycles under baseflow conditions in headwater streams. However, further research in a variety of fluvial environments is required to better assess the spatial extent, importance and causal mechanisms of this phenomenon

Models of the cardiac L-type calcium current: a quantitative comparison

The L-type calcium current (ICaL) plays a critical role in cardiac electrophysiology, and models of ICaL are vital tools to predict arrhythmogenicity of drugs and mutations. Five decades of measuring and modelling ICaL have resulted in several competing theories (encoded in mathematical equations). However, the introduction of new models has not typically been accompanied by a data-driven critical comparison with previous work, so that it is unclear where predictions overlap or conflict, or which model is best suited for any particular application. We gathered 71 mammalian ICaL models, compared their structure, and reproduced simulated experiments to show that there is a large variability in their predictions, which was not substantially diminished when grouping by species or other categories. By highlighting the differences in these competing theories, listing major data sources, and providing simulation code, we have laid strong foundations for the development of a consensus model of ICaL

Surface tension, density and composition in the methane-pentane system at high pressure

A pressure system is described for measuring the pressure dependence of surface tension using digital image processing techniques on pendant drops in systems where the miscibility changes with both temperature and pressure. Measurements can be performed at pressures up to 40 MPa and temperatures up to 423 K. This high-pressure rig allows, additionally, the simultaneous measurement of both phase density and composition. The system is tested with the methane-pentane system at 313.15 K and pressures up to 15.6 MPa; the results compare well with literature data and with values calculated using the Peng-Robinson equation of state in conjunction with the gradient theory approach to computing surface tension, thus validating the experimental technique. Density profiles of the components through the interfacial layer have also been calculated using gradient theory. The Wegner extended scaling approach has been applied to all of the data sets to estimate the critical pressure for this system, which is found to be 16 MPa at 313.15 K