The role of B-site cations on proton conductivity in double perovskite oxides La2MgTiO6 and La2MgZrO6

Acceptor-doped La₂MgTiO₆ (LMTO) and La₂MgZrO₆ (LMZO) have been investigated to contribute to clarify the role of the B-site cations in A₂B′B″O₆ double perovskite oxides on formation and mobility of protons. Thermogravimetry and a.c. conductivity measurements in the temperature range 1000-300 °C, as well as DFT-calculations of LMTO, have been the basis for evaluating hydration thermodynamics and transport parameters of the materials. Both compounds show exothermic hydration of oxygen vacancies, but low concentrations of protons. The proton transport is limited by relatively high activation energies of mobility; 0.84 eV and 0.78 eV for LMTO and LMZO, respectively. This is suggested to reflect association to effectively negative charged defects formed by site exchange among the B-site cations. Consequently, the maximum proton conductivity of LMTO and LMZO is in the order of 10⁻⁵ S/cm.     

Hepatic lipogenic enzyme expression in pigs is affected by selection for decreased backfat thickness at constant intramuscular fat content

This study investigated (i) whether genetic selection for decreased backfat thickness at constant intramuscular fat (IMF) affects the expression of lipogenic enzymes in pig liver and (ii) whether expression of the hepatic lipogenic enzymes is related to subcutaneous fat and IMF fatty acid composition. The enzymes investigated were fatty acid synthase (FAS), stearoyl-CoA desaturase and Δ6-desaturase (Δ6d). Experiments were conducted on 30 barrows (15 controls and 15 selected). Selected pigs had lower backfat thickness, which was accompanied by a reduced expression of the hepatic FAS and Δ6d when compared to control pigs. There was a trend towards a positive relationship between FAS and Δ6d protein expression and saturated and polyunsaturated fatty acids content respectively, in subcutaneous fat but not in muscle. It was concluded that selection against backfat thickness is associated with changes in expression of the hepatic FAS and Δ6d proteins. The changes in protein expression did not influence significantly the tissue fatty acid composition under these conditions.     

Guiding functional design of mechanical products through rule-based causal behavioural reasoning

The paper presents a behaviour-driven functional (B-FES) modelling framework for functional design of mechanical products based on a rule-based causal behavioural reasoning step to guide the design process. A new representation scheme called rule-based behavioural representation (causal behavioural rules) was developed to facilitate causal behavioural reasoning, with which the interconnected physical behaviours can be reasoned out from a desired function. The behaviour schema was then used to select and arrange embodiments (abstractions of physical artefacts) to develop a set of potential concept variants. The proposed approach was not only useful in the creation of new configurations (combinations) from a library of standard physical behaviours, but also it might be used to generate specifications of new physical behaviours. A design case study of a terminal feeding unit is presented to demonstrate the practicality of the proposed approach.     

(Super)hydrophobic and Multilayered Amphiphilic Films Prepared by Continuous Assembly of Polymers

The continuous assembly of polymers (CAP) is used to fabricate tailored nanocoatings on a wide variety of substrates. Ring‐opening metathesis polymerization (ROMP) is used to mediate the CAP process (CAP_ROMP) to assemble specifically designed macromolecules into nanoengineered crosslinked films. Different films composed of single or multiple macromolecules are used to tune the surface wetting characteristics on various planar substrates, including porous substrates such as filter paper and cotton, and non‐porous subtrates such as aluminium foil and glass. By judicious selection of the macromolecules, these substrates, which are hydrophilic in nature, can be rendered (super)hydrophobic. The robustness of the ROMP catalysts and the reinitiation ability of the CAP_ROMP approach allow the production of layered multicomponent amphiphilic films with on‐demand switchable wettability. Such functional nanocoatings can be potentially applied as self‐cleaning surfaces, as waterproof woven fabrics, and for the next generation of microelectronic devices.     

Stunning and animal welfare from Islamic and scientific perspectives

The transformation of an animal into pieces fit for human consumption is a very important operation. Rather than argue about halal slaughter without stunning being inhumane or stunning being controversial from the Islamic point of view, we discuss slaughter, stunning and animal welfare considering both Islamic and animal welfare legislation requirements. With the world Muslim population close to two billion, the provision of halal meat for the Muslim community is important both ethically and economically. However, from the animal welfare standard point of view, a number of issues have been raised about halal slaughter without stunning, particularly, about stressful methods of restraint and the latency of the onset of unconsciousness. This paper sets out to, discuss the methods of stunning that are acceptable by Islamic authorities, highlight the requirements for stunning to be acceptable in Islam and suggest practical ways to improve the humanness of slaughter.     

On the Origin of the Canonical Nucleobases: An Assessment of Selection Pressures across Chemical and Early Biological Evolution

The native bases of RNA and DNA are prominent examples of the narrow selection of organic molecules upon which life is based. How did nature “decide” upon these specific heterocycles? Evidence suggests that many types of heterocycles could have been present on the early Earth. It is therefore likely that the contemporary composition of nucleobases is a result of multiple selection pressures that operated during early chemical and biological evolution. The persistence of the fittest heterocycles in the prebiotic environment towards, for example, hydrolytic and photochemical assaults, may have given some nucleobases a selective advantage for incorporation into the first informational polymers. The prebiotic formation of polymeric nucleic acids employing the native bases remains, however, a challenging problem to reconcile. Hypotheses have proposed that the emerging RNA world may have included many types of nucleobases. This is supported by the extensive utilization of non-canonical nucleobases in extant RNA and the resemblance of many of the modified bases to heterocycles generated in simulated prebiotic chemistry experiments. Selection pressures in the RNA world could have therefore narrowed the composition of the nucleic acid bases. Two such selection pressures may have been related to genetic fidelity and duplex stability. Considering these possible selection criteria, the native bases along with other related heterocycles seem to exhibit a certain level of fitness. We end by discussing the strength of the N-glycosidic bond as a potential fitness parameter in the early DNA world, which may have played a part in the refinement of the alphabetic bases.     

Influence of Milling Media on the Physicochemicals and Catalytic Properties of Mechanochemical Treated Vanadium Phosphate Catalysts

Abstract  

VOHPO₄·0.5H₂O synthesized via the alcohol reduction of VOPO₄·2H₂O was mechanochemical treated for 30 min in three different media, i.e. cyclohexane, ethanol and air. XRD results revealed that their structure became less crystalline compared to the unmilled material. SEM showed that the particles for the milled materials become smaller and unique features were observed in the different type of media used. The reactivity of the oxygen species linked to V⁵⁺ and V⁴⁺ were also affected by the milling process. The selectivity to maleic anhydride from n-butane oxidation were observed to increase in line with the increase in the oxygen species associated with V⁵⁺ and the presence of isolated V⁵⁺ phase. A correlation was observed between the crystallite size of the pyrophosphate phase at (020) plane with the maleic anhydride selectivity.