Software transactional memories for Scala

Transactional memory is an alternative to locks for handling concurrency in multi-threaded environments. Instead of providing critical regions that only one thread can enter at a time, transactional memory records sufficient information to detect and correct for conflicts if they occur. This paper surveys the range of options for implementing software transactional memory in Scala. Where possible, we provide references to implementations that instantiate each technique. As part of this survey, we document for the first time several techniques developed in the implementation of Manchester University Transactions for Scala. We order the implementation techniques on a scale moving from the least to the most invasive in terms of modifications to the compilation and runtime environment. This shows that, while the less invasive options are easier to implement and more common, they are more verbose and invasive in the codes using them, often requiring changes to the syntax and program structure throughout the code.     

Chemical composition, mineral content and antioxidant activity of Verbena officinalis L.

Aqueous and hydroalcoholic extracts from Verbena officinalis L. were obtained and characterised. The analysis by HPLC-DAD and LC-MS allowed the detection and identification of three iridoids, fifteen flavonoids and four phenolic acid derivatives. Four flavonoids, scutellarein 7-diglucuronide (9), scutellarein 7-glucuronide (13), pedalitin 6-galactoside (15) and scutellarein 7-glucoside (19) are reported for the first time from this plant. In addition, three new flavonoids have been isolated: scutellarein 7-O-(2-O-feruloyl)-diglucuronide (5), pedalitin 6-O-diglucuronide (6) and pedalitin 6-O-(2-O-feruloyl)-diglucuronide (13). To our knowledge, these flavonoids have not been reported as natural products. Both extracts showed significant antioxidant activity using three in vitro model systems and the results have been correlated with total phenolic and total flavonoid contents. The results have allowed establishing an important relation structure-activity and significant correlations have also been found between the mineral content and the flavonoids present in both extracts.     

Nafion/polyaniline/silica composite membranes for direct methanol fuel cell application

This work investigates the characterization and performance of polyaniline and silica modified Nafion membranes. The aniline monomers are synthesized in situ to form a polyaniline film, whilst silica is embedded into the Nafion matrix by the polycondensation of tetraethylorthosilicate. The physicochemical properties are studied by means of X-ray diffraction and Fourier transform infrared techniques and show that the polyaniline layer is formed on the Nafion surface and improves the structural properties of Nafion in methanol solution. Nafion loses its crystallinity once exposed to water and ethanol, whilst the polyaniline modification allows crystallinity to be maintained under similar conditions. By contrast, the proton conductivities of polyaniline modified membranes are 3–5-fold lower than that of Nafion. On a positive note, methanol crossover is reduced by over two orders of magnitude, as verified by crossover limiting current analysis. The polyaniline modification allows the membrane to become less hydrophilic, which explains the lower proton conductivity. No major advantages are observed by embedding silica into the Nafion matrix. The performance of a membrane electrode assembly (MEA) using commercial catalysts and polyaniline modified membranes in a cell gives a peak power of 8 mW cm⁻² at 20 °C with 2 M methanol and air feeding. This performance correlates to half that of MEAs using Nafion, though the membrane modification leads to a robust material that may allow operation at high methanol concentration.     

Effects of nicotine dose and administration method on withdrawal symptoms and side effects during short-term smoking abstinence.

The effects of using several different nicotine replacement treatments on self-reported withdrawal symptoms and side effects during 2-day periods of smoking cessation, with 5 days of ad lib smoking between cessation days, were evaluated. Participants (N ?=?18) experienced the following conditions: nicotine gum, 24-hr patch, 16-hr patch, 24-hr patch plus gum, double 24-hr patch, and no nicotine replacement. The present study found morning urge to smoke was greater during the 16-hr than during the 24-hr patch condition. Double-patch use resulted in significantly greater insomnia than the smoking baseline and 16-hr patch conditions. The no medication and gum alone conditions resulted in similar withdrawal symptoms, and both tended to result in greater reported withdrawal symptoms than the smoking baseline condition. There were no significant withdrawal symptom differences between the 24-hr, patch-gum, and double-patch conditions. The 24-hr and double-patch conditions were preferred by two thirds of the participants (6 each). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An engineering approach for the estimation of slewing bearing stiffness in wind turbine generators

The stiffness of yaw and pitch slewing bearings has a critical influence on the structural behaviour of wind turbine generators. Thus, it is commonly required by designers for their simulations to estimate deformations and select the most suitable bearing for their working conditions in preliminary design stages. In this work, a design of experiments was carried out via finite element analysis to obtain the stiffness curves of all of the standard four‐point contact slewing bearings from the catalogues of manufacturers under radial, axial, and tilting loads. From these results, a set of simple formulas to calculate the ring deformations were adjusted. Combining them with contact deformation results obtained in previous work by the authors, a complete and efficient tool for slewing bearing stiffness estimation has been developed.     

Polymers beyond standard optical fibres – fabrication of microstructured polymer optical fibres

This paper reports the overall fabrication process of microstructured polymer optical fibres (mPOFs). mPOF fabrication involves a two‐step process: on the one hand, the design and creation of a preform containing a large‐scale version of the desired fibre and, on the other, the precise heating and drawing of the preform to the final fibre. The preforms are produced either by an improved drilling technique or by capillary stacking. For a correct and accurate drawing of the fibre, a controlled and precise heating unit has to be designed, an issue that will be explained in detail in this work. The quality and optical performance of the final mPOF depends strongly on key factors such as the preform annealing, the accuracy of the technique selected for the creation of the preform structure, the heating stage, as well as on the drawing parameters. All of them are analysed in detail and some drawn mPOFs of interest are reported as well. © 2018 Society of Chemical Industry     

Cover Image,Volume 67, Issue 9

The cover image, by Eneko Arrospide et al., is based on the Review Polymers beyond standard optical fibres ‐ fabrication of microstructured polymer optical fibres, DOI: 10.1002/pi.5602 .