Plate wave resonance with air-coupled ultrasonics

Air‐coupled ultrasonic transducers can excite plate waves in metals and composites. The coincidence effect, i.e., the wave vector of plate wave coincides with projection of exciting airborne sound vector, leads to a resonance which strongly amplifies the sound transmission through the plate. The resonance depends on the angle of incidence and the frequency. In the present study, the incidence angle for maximum transmission (θmax)is measured in plates of steel, aluminum, carbon fiber reinforced composites and honeycomb sandwich panels. The variations of (θmax) with plate thickness are compared with theoretical values in steel, aluminum and quasi‐isotropic carbon fiber composites. The enhanced transmission of air‐coupled ultrasound at oblique incidence can substantially improve the probability of flaw detection in plates and especially in honeycomb structures. Experimental air‐coupled ultrasonic scan of subtle flaws in CFRP laminates showed definite improvement of signal‐to‐noise ratio with oblique incidence atθmax

Terminology and tensions within evidence-informed decision-making in South Africa over a 15-year period

In this article, we examine a key premise underlying evidence-informed decisionmaking (EIDM) – that research is for all, including service users and potential users, service providers and a wide range of decision-makers, from those running local services to national government officials and international agencies. Qualitative data collected on terminology used when writing and talking about EIDM over a period of 15 years during the implementation of a number of capacity development programmes in South Africa were combined with critical reflections in practice. Findings reveal that tensions exist in the titles and terminology used to describe the relationships between academia and government or between research and policy, and that these tensions have shifted over time, but not necessarily diminished. An analysis and critique of this terminology is provided to identify and unpack these tensions, which challenge the central premise of 'research for all'. The perpetuation of divisive labels that profile people, of job titles and specific terminology that describe agency, as well as the use of technical language, continues to exclude people from the approach. These have the effect of setting up users against producers of evidence. In conclusion, we challenge the advocates of the EIDM approach to review language and terminology to be more inclusive, to enable relationship-building and ease the process of engagement to ensure evidence-informed decision-making is true to its premise that research is for all

The tyranny of adenosine recognition among RNA aptamers to coenzyme A

BACKGROUND: Understanding the diversity of interactions between RNA aptamers and nucleotide cofactors promises both to facilitate the design of new RNA enzymes that utilize these cofactors and to constrain models of RNA World evolution. In previous work, we isolated six pools of high affinity RNA aptamers to coenzyme A (CoA), the principle cofactor in biological acyltransfer reactions. Interpretation of the evolutionary significance of those results was made difficult by the fact that the affinity resin attachment strongly influenced the outcome of those selections. Here we describe the selection of four new pools isolated on a disulfide-linked CoA affinity matrix to minimize context-dependent recognition imposed by the attachment to the solid support. RESULTS: The four new aptamer libraries show no sequence or structural relation to a previously dominant CoA-binding species, even though they were isolated from the same initial random libraries. Recognition appears to be limited to the adenosine portion of the CoA – in particular the Höogsteen edge – for most isolates surveyed, even when a counter selection was employed to remove such RNAs. Two of the recovered isolates are eluted with intact CoA more efficiently than with AMP alone suggesting a possible pantotheine interaction. However, a detailed examination of recognition specificity revealed that the 3' phosphate of CoA, and not the pantotheine arm, determined recognition by these two isolates. CONCLUSION: Most aptamers that have been targeted towards cofactors containing adenosine recognize only the adenosine portion of the cofactor. They do not distinguish substituents on the 5' carbon, even when those substituents have offered hydrogen bonding opportunities and the selection conditions discouraged adenosine recognition. Beyond hydrogen bonding, additional factors that guide the selection towards adenosine recognition include aromatic stacking interactions and relatively few rotational degrees of freedom. In the present work, a sterically accessible, disulfide-linked CoA affinity resin afforded the selection of a more diverse aptamer collection then previous work with a N6 linked CoA resin

Microbiological Spoilage of Aviation Turbine Fuel: Part II Evaluation of a Suitable Biocide

Addition of ethylene glycol monoethyl ether, an anti-icing fuel additive supports microbial growth when added to aviation turbine fuel in low dosages. however, increases in its concentration to certain limits effectively prevents bioactivity in the fuel. The optimum dosage of this biocide for prevention of bioactivity in aviation turbine fuel has been studied by the specified qualitative performance tests after 18 months storage of the inhibited fuel under accelerated conditions of temperature and humidity

Prevention of Fungal Growth on Rubber Earpads of Telecommunication Equipments

This paper recommends an addition of 100% zinc oxide to the rubber composition during its manufacture to effectively prevent fungal growth on the earpads without producing any adverse on its materials/performance or the user

Underground Corrosion by Microorganisms Part II : Role of Anaerobic Sulphate Reducing Bacteria-Desulfotomaculum SP

During the course of studies on the corrosion causing soil microflora from different geoclimatic regions of India, several strains of anaerobic sulphate reducing bacteria belonging to genus Desulfotomaculum were isolated and characterised. Their corrosive action on mild steel, galvanised iron and structural aluminium, the three main metals of construction of underground structures, have been studied under laboratory conditions