Modulation of ion channels by hydrogen sulfide

Increasing current awareness and understanding of the roles and mechanisms of action of ion channel regulation by H(2)S will open opportunities for therapeutic intervention with clear clinical benefits, and inform future therapies. In addition, more sensitive methods for detecting relevant physiological concentrations of H(2)S will allow for clarification of specific ion channel regulation with reference to physiological or pathophysiological settings.

Threats to an ecosystem service: pressures on pollinators

Insect pollinators of crops and wild plants are under threat globally and their decline or loss could have profound economic and environmental consequences. Here, we argue that multiple anthropogenic pressures – including land-use intensification, climate change, and the spread of alien species and diseases – are primarily responsible for insect-pollinator declines. We show that a complex interplay between pressures (eg lack of food sources, diseases, and pesticides) and biological processes (eg species dispersal and interactions) at a range of scales (from genes to ecosystems) underpins the general decline in insect-pollinator populations. Interdisciplinary research on the nature and impacts of these interactions will be needed if human food security and ecosystem function are to be preserved. We highlight key areas that require research focus and outline some practical steps to alleviate the pressures on pollinators and the pollination services they deliver to wild and crop plants.

On the use of a time sequence of surface pressures in four-dimensional data assimilation

The possibility of using a time sequence of surface pressure observations in four-dimensional data assimilation is being investigated. It is shown that a linear multilevel quasi-geostrophic model can be updated successfully with surface data alone, provided the number of time levels are at least as many as the number of vertical levels. It is further demonstrated that current statistical analysis procedures are very inefficient to assimilate surface observations, and it is shown by numerical experiments that the vertical interpolation must be carried out using the structure of the most dominating baroclinic mode in order to obtain a satisfactory updating. Different possible ways towards finding a practical solution are being discussed.

Hydrogen bonding in the gas-phase: the molecular structures of 2‑hydroxybenzamide (C7H7NO2) and 2‑methoxybenzamide (C8H9NO2), obtained by gas-phase electron diffraction and theoretical calculations

The structures of 2-hydroxybenzamide(C7H7NO2) and 2-methoxybenzamide (C8H9NO2) have been determined in the gas-phase by electron diffraction using results from quantum chemical calculations to inform restraints used on the structural parameters. Theoretical methods (HF and MP2/6-311+G(d,p)) predict four stable conformers for both 2-hydroxybenzamide and 2-methoxybenzamide. For both compounds, evidence for intramolecular hydrogen bonding is presented. In 2-hydroxybenzamide, the observed hydrogen bonded fragment is between the hydroxyl and carbonyl groups, while in 2-methoxybenzamide, the hydrogen bonded fragment is between one of the hydrogen atoms of the amide group and the methoxy oxygen atom.

Application of hydrogen-bond propensity calculations to an indomethacin–nicotinamide (1:1) co-crystal

The crystal structure of an indomethacin–nicotinamide (1 : 1) cocrystal produced by milling has been determined from laboratory powder X-ray diffraction (PXRD) data. The hydrogen bonding motifs observed in the structure represent one of the most probable of all the possible combinations of donors and acceptors in the constituent molecules.

A microblock ionomer in proton exchange membrane electrolysis for the production of high purity hydrogen

Proton exchange membranes (PEM’s) are currently under investigation for membrane water electrolysis (PEMWE) to deliver efficient production of the high purity hydrogen needed to supply emerging clean-energy technologies such as hydrogen fuel cells. The microblock aromatic ionomer described in this work achieves high mechanical strength in an aqueous environment as a result of its designed, biphasic morphology and displays many of the qualities required in a PEM. The new ionomer membrane thus shows good proton conductivity (63 mS cm−1 at 80 °C and 100% RH), while retaining mechanical integrity under high temperature, hydrated conditions. Testing in electrolysis has shown good energy efficiency (1.67 V at 1 A cm−2 and 80 °C, corresponding to 4 kWh/Nm3 of H2), making this ionomer a potential candidate for commercial application in PEMWE.

Combined effects of global change pressures on animal-mediated pollination

Pollination is an essential process in the sexual reproduction of seed plants and a key ecosystem service to human welfare. Animal pollinators decline as a consequence of five major global change pressures: climate change, landscape alteration, agricultural intensification, non-native species, and spread of pathogens. These pressures, which differ in their biotic or abiotic nature and their spatiotemporal scales, can interact in nonadditive ways (synergistically or antagonistically), but are rarely considered together in studies of pollinator and/or pollination decline. Management actions aimed at buffering the impacts of a particular pressure could thereby prove ineffective if another pressure is present. Here, we focus on empirical evidence of the combined effects of global change pressures on pollination, highlighting gaps in current knowledge and future research needs.

Factors affecting hydrogen uptake by bacteria growing in the human large intestine

The human large intestine is a highly complex ecosystem that contains somewhere in the region of 400 different species of bacterial1.The vast majority of these bacteria are strict anaerobes and grow on a wide variety of substrates that have either escaped digestion in the small bowel or have been produced by the host2. In Western populations, between 10–60g of carbohydrate and 6–18g of proteinaceous material are potentially available for fermentation each day, producing a total bacterial mass of approximately 90g3.

Hollow capsules formed in a single stage via interfacial hydrogen-bonded complexation of methylcellulose with poly(acrylic acid) and tannic acid

Hollow capsules can be prepared in a single stage by the interfacial complexation of methylcellulose (MC) with poly(acrylic acid) (PAA) or tannic acid (TA) via hydrogen bonding in aqueous solutions. The formation of capsules is observed when viscous solution of methylcellulose is added drop-wise to diluted solutions of polyacids under acidic conditions. The optimal parameters such as polymer concentration and solution pH for the formation of these capsules were established in this work. It was found that tannic acid forms capsules in a broader range of concentrations and pHs compared to poly(acrylic acid). The TA/MC capsules exhibited better stability compared to PAA/MC in response to increase in pH: the dissolution of TA/MC capsules observed at pH > 9.5; whereas PAA/MC capsules dissolved at pH > 3.8. The interfacial complexation can be considered as a potential single stage alternative to the formation of capsules using multistage layer-by-layer deposition method.

Hydrogen-bonded complexes and blends of poly(acrylic acid) and methylcellulose: nanoparticles and mucoadhesive films for Ocular Delivery of Riboflavin

Poly(acrylic acid) (PAA) and methylcellulose (MC) are able to form hydrogen-bonded interpolymer complexes (IPCs) in aqueous solutions. In this study, the complexation between PAA andMC is explored in dilute aqueous solutions under acidic conditions. The formation of stable nanoparticles is established,whose size and colloidal stability are greatly dependent on solution pH and polymers ratio in the mixture. Poly(acrylic acid) and methylcellulose are also used to prepare polymeric films by casting from aqueous solutions. It is established that uniform films can be prepared by casting from polymer mixture solutions at pH 3.4–4.5. At lower pHs (pH<3.0) the films have inhomogeneous morphology resulting from strong interpolymer complexation and precipitation of polycomplexes, whereas at higher pHs (pH 8.3) the polymers form fully immiscible blends because of the lack of interpolymer hydrogen-bonding. The PAA/MC films cast at pH 4 are shown to be non-irritant to mucosal surfaces. These films provide a platform for ocular formulation of riboflavin, a drug used for corneal crosslinking in the treatment of keratoconus. An in vitro release of riboflavin as well as an in vivo retention of the films on corneal surfaces can be controlled by adjusting PAA/MC ratio in the formulations.