Strong polarized relations for the continuum

We prove that the strong polarized relation for the continuum holds for $\aleph_0$ and for every supercompact cardinal. We use iteration of Mathias forcing.Comment: 9 page

Double-network hydrogels improve pH-switchable adhesion

For environmentally-switchable adhesive systems to be reused repeatedly, the adhesive strength must not deteriorate after each adhesion cycle. An important criterion to achieve this goal is that the integrity of the interface must be retained after each adhesion cycle. Furthermore, in order to have practical benefits, reversing the adhesion must be a relatively rapid process. Here, a double-network hydrogel of poly(methacrylic acid) and poly[oligo(ethylene glycol)methyl ether methacrylate] is shown to undergo adhesive failure during pH-switchable adhesion with a grafted (brush) layer of polycationic poly[2-(diethyl amino)ethyl methacrylate], and can be reused at least seven times. The surfaces are attached at pH 6 and detached at pH 1. A single-network hydrogel of poly(methacrylic acid), also exhibits pH-switchable adhesion with poly[2-(diethyl amino)ethyl methacrylate] but cohesive failure leads to an accumulation of the hydrogel on the brush surface and the hydrogel can only be reused at different parts of that surface. Even without an environmental stimulus (i.e. attaching and detaching at pH 6), the double-network hydrogel can be used up to three times at the same point on the brush surface. The single-network hydrogel cannot be reused under such circumstances. Finally, the time taken for the reuse of the doublenetwork hydrogel is relatively rapid, taking no more than an hour to reverse the adhesion

The effect of magnesium ions on triphosphate hydrolysis

The role of metal ions in catalyzing phosphate ester hydrolysis has been the subject of much debate, both in terms of whether they change the transition state structure or mechanistic pathway. Understanding the impact of metal ions on these biologically critical reactions is central to improving our understanding of the role of metal ions in the numerous enzymes that facilitate them. In the present study, we have performed density functional theory studies of the mechanisms of methyl triphosphate and acetyl phosphate hydrolysis in aqueous solution to explore the competition between solvent- and substrate-assisted pathways, and examined the impact of Mg2+ on the energetics and transition state geometries. In both cases, we observe a clear preference for a more dissociative solvent-assisted transition state, which is not significantly changed by coordination of Mg2+. The effect of Mg2+ on the transition state geometries for the two pathways is minimal. While our calculations cannot rule out a substrate-assisted pathway as a possible solution for biological phosphate hydrolysis, they demonstrate that a significantly higher energy barrier needs to be overcome in the enzymatic reaction for this to be an energetically viable reaction pathway

Global Symposium on Women in Fisheries

All over the world, women contribute in multiple ways to the production, processing, marketing and management of fish and other living aquatic resources. The first ever Global Symposium on Women in Fisheries, held in Kaohsiung, Taiwan on 29 November 2001 generated the present collection of papers on women in fisheries. The reader of this volume will find in it a wealth of information, albeit in a very heterogeneous form, that the authors have had to draw from many different sources. Some are primary research studies whereas most are historical reviews from first hand experience of the authors or derived from other written materials, often contained in reports of fisheries development projects, newspapers and source materials well outside the fish sectors.Women, Participation, Sustainability, Poverty, Fisheries, Development projects, Fishery technology

Coordination‐cage‐catalysed hydrolysis of organophosphates : cavity‐ or surface‐based?

The hydrophobic central cavity of a water‐soluble M8L12 cubic coordination cage can accommodate a range of phospho‐diester and phospho‐triester guests such as the insecticide “dichlorvos” (2,2‐dichlorovinyl dimethyl phosphate) and the chemical warfare agent analogue di(isopropyl) chlorophosphate. The accumulation of hydroxide ions around the cationic cage surface due to ion‐pairing in solution generates a high local pH around the cage, resulting in catalysed hydrolysis of the phospho‐triester guests. A series of control experiments unexpectedly demonstrates that—in marked contrast to previous cases—it is not necessary for the phospho‐triester substrates to be bound inside the cavity for catalysed hydrolysis to occur. This suggests that catalysis can occur on the exterior surface of the cage as well as the interior surface, with the exterior‐binding catalysis pathway dominating here because of the small binding constants for these phospho‐triester substrates in the cage cavity. These observations suggest that cationic but hydrophobic surfaces could act as quite general catalysts in water by bringing substrates into contact with the surface (via the hydrophobic effect) where there is also a high local concentration of anions (due to ion pairing/electrostatic effects)

Transition States and Control of Substrate Preference in the Promiscuous Phosphatase PP1

Catalytically promiscuous enzymes are an attractive frontier for biochemistry, because enzyme promiscuities not only plausibly explain enzyme evolution through the mechanism of gene duplication but also could provide an efficient route to changing the catalytic function of proteins by mimicking this evolutionary process. PP1γ is an effectively promiscuous phosphatase for the hydrolysis of both monoanionic and dianionic phosphate ester-based substrates. In addition to its native phosphate monoester substrate, PP1γ catalyzes the hydrolysis of aryl methylphosphonates, fluorophosphate esters, phosphorothioate esters, and phosphodiesters, with second-order rate accelerations that fall within the narrow range of 10(11)-10(13). In contrast to the different transition states in the uncatalyzed hydrolysis reactions of these substrates, PP1γ catalyzes their hydrolysis through similar transition states. PP1γ does not catalyze the hydrolysis of a sulfate ester, which is unexpected. The PP1γ active site is tolerant of variations in the geometry of bound ligands, which permit the effective catalysis even of substrates whose steric requirements may result in perturbations to the positioning of the transferring group, both in the initial enzyme-substrate complex and in the transition state. The conservative mutation of arginine 221 to lysine results in a mutant that is a more effective catalyst toward monoanionic substrates. The surprising conversion of substrate preference lends support to the notion that mutations following gene duplication can result in an altered enzyme with different catalytic capabilities and preferences and may provide a pathway for the evolution of new enzymes

Simulating the reactions of substituted pyridinio-N-phosphonates with pyridine as a model for biological phosphoryl transfer

Phosphoryl transfer reactions can proceed through several plausible mechanisms, and the potential for both solvent and substrate-assisted pathways (involving proton transfer to the phosphoryl oxygens) complicates both experimental and computational interpretations. To avoid this problem, we have used electronic structure calculations to probe the mechanisms of the reactions of pyridinio-N-phosphonates with pyridine. These compounds avoid the additional complexity introduced by proton transfer between the nucleophile and the leaving group, while also serving as a valuable model for biological P-N cleavage. Through a comparative study of a range of substrates of varying basicity, we demonstrate a unified concerted mechanism for the phosphoryl transfer reactions of these model compounds, proceeding through a dissociative transition state. Finally, a comparison of these transition states with previously characterized transition states for related compounds provides a more complete model for non-enzymatic phosphoryl transfer, which is a critical stepping stone to being able to fully understand phosphoryl transfer in biology

How to name atoms in phosphates, polyphosphates, their derivatives and mimics, and transition state analogues for enzyme-catalysed phosphoryl transfer reactions (IUPAC Recommendations 2016)

Procedures are proposed for the naming of individual atoms, P, O, F, N, and S in phosphate esters, amidates, thiophosphates, polyphosphates, their mimics, and analogues of transition states for enzyme-catalyzed phosphoryl transfer reactions. Their purpose is to enable scientists in very different fields, e.g. biochemistry, biophysics, chemistry, computational chemistry, crystallography, and molecular biology, to share standard protocols for the labelling of individual atoms in complex molecules. This will facilitate clear and unambiguous descriptions of structural results, as well as scientific intercommunication concerning them. At the present time, perusal of the Protein Data Bank (PDB) and other sources shows that there is a limited degree of commonality in nomenclature, but a large measure of irregularity in more complex structures. The recommendations described here adhere to established practice as closely as possible, in particular to IUPAC and IUBMB recommendations and to "best practice" in the PDB, especially to its atom labelling of amino acids, and particularly to Cahn-Ingold-Prelog rules for stereochemical nomenclature. They are designed to work in complex enzyme sites for binding phosphates but also to have utility for non-enzymatic systems. Above all, the recommendations are designed to be easy to comprehend and user-friendly

Map-based estimates of present carbon stocks of grazing lands in Sub-Sahara Africa

This report is a detailed review, synthesis, and analysis of the current “state of the science” concerning the potential for carbon sequestration in grazing lands through improved land management practices in Sub-Saharan Africa (SSA). It aims to provide an up-to-date assessment of the science of C sequestration from improved land management, including the current levels of uncertainty, major gaps in knowledge and data, areas for near term research and development, major determinants of sequestration potential, and current and potential scientific monitoring tools. The report firstly gives an overview of current grazing lands in SSA (Chapter 1) and explores the major determinants of C sequestration in grass/rangeland systems (Chapter 2). It then considers current research work on C impacts of grazing land management systems (Chapter 3). Available measurement techniques are summarized in Chapter 4 and a map based approach is then used in Chapter 5 to estimate present C stocks in grazing lands in SSA. This is followed by Chapter 6 which looks at available modeling techniques and Chapter 7 which presents a model based estimate of C sequestration potential in grass/rangelands in SSA. The final chapter (Chapter 8) provides a synthesis of the report’s findings. > Authors of the respective chapters: Eleanor Milne · Stephen Williams · Andre Bationo · Robin Reid · David Swift · Rich Conant · Niall Hanan · Constance Neely · Ermias Aynekulu · Keith D. Shepherd · Niels Batjes · Randall Boon

Hip fracture in the elderly multidisciplinary rehabilitation (FEMuR) feasibility study: testing the use of routinely collected data for future health economic evaluations

Background: Health economic evaluations rely on the accurate measurement of health service resource use in order to calculate costs. These are usually measured with patient completed questionnaires using instruments such as the Client Service Receipt Inventory (CSRI). These rely on participants' recall and can be burdensome to complete. Health service activity data are routinely captured by electronic databases.The aim was to test methods for obtaining these data and compare with those data collected using the CSRI, within a feasibility study of an enhanced rehabilitation intervention following hip fracture (Fracture in the Elderly Multidisciplinary Rehabilitation: FEMuR). Methods: Primary care activity including prescribing data was obtained from the Secure Anonymised Information Linkage (SAIL) Databank and secondary care activity (Emergency Department attendances, out-patient visits and in-patient days) directly from Betsi Cadwaladr University Health Board (BCUHB), North Wales, UK. These data were compared with patient responses from the CSRI using descriptive statistics and the intraclass correlation coefficient (ICC). Results: It was possible to compare health service resource use data for 49 out of 61 participants in the FEMuR study. For emergency department (ED) attendances, records matched in 23 (47%) cases, 21 (43%) over-reported on electronic records compared with CSRI and five participants (10%) under-reported, with an overall ICC of 0.42. For out-patient episodes, records matched in only six cases, 28 participants over-reported on electronic records compared with CSRI and 15 (12%) under-reported, with an overall ICC of only 0.27. For in-patient days, records matched exactly in only five cases (10%), but if an error margin of 7 days was allowed, then agreement rose to 39 (66%) cases, and the overall ICC for all data was 0.88.It was only possible to compare prescribing data for 12 participants. For prescribing data, the SAIL data reported 117 out of 118 items (99%) and the CSRI only 89 (79%) items. Conclusions: The use of routinely collected data has the potential to improve the efficiency of trials and other studies. Although the methodology to make the data available has been demonstrated, the data obtained was incomplete and the validity of using this method remains to be demonstrated. Trial registration: Trial registration: ISRCTN22464643 Registered 21 July 2014