On the bond distance in methane

The equilibrium bond distance in methane was optimized using coupled-pair functional and contracted CI wave functions, and a Gaussian basis that includes g-type functions on carbon and d-type functions on hydrogen. The resulting bond distance, when corrected for core-valence correlation effects, agrees with the experimental value of 2.052 a(0) to within the experimental uncertainty of 0.002 a(0). The main source of error in the best previous studies, which showed discrepancies with experiment of 0.007 a(0) is shown to be basis set incompleteness. In particular, it is important that the basis set be close to saturation, at least for the lower angular quantum numbers

Investigation of the effect of hot water and water vapour treatments on the strength of thermally conditioned E-glass fibres

The processing and reuse of end-of-life composite products in an environmentally friendly manner is an important challenge facing the industry. The development of an economically viable process for regenerating the properties of thermally recycled glass fibres would have significant technological, economic and environmental impacts. Thermal recycling processes for composites are relatively technologically advanced; however, they present a substantial challenge when considering their use for recycling of glass fibre reinforced materials. A combination of exposure to elevated temperatures in the region 450 – 600 °C and to mechanical damage has been shown to cause significant strength loss in glass fibres of up to 90 % of their original value. The recovered fibres are thus unsuitable for use as reinforcement in a second generation composite. Methods of strength recovery that may be applied to such recycled fibres are therefore of interest, particularly if these methods are relatively technologically straightforward. An investigation of possible strength recovery methods using hot water or water vapour was carried out on E-glass fibres. The methods were derived from similar studies on silica in which significant strengthening effects were presented alongside theoretical frameworks to explain the phenomenon [1–3]; a maximum threefold increase in strength following water vapour treatment at 250 °C was demonstrated on silica artificially weakened by abrasion

Myiasis-induced sepsis: a rare case report of: Wohlfahrtiimonas chitiniclastica: and: Ignatzschineria indica: bacteremia in the continental United States

Rationale: The presentation of sepsis and bacteremia in cutaneous and cavitary myiasis is uncommon. We present a patient, residing in a temperate region of the United States, with myiasis and sepsis from the emerging human pathogens Wohlfahrtiimonas chitiniclastica and Ignatzschineria indica. Patient concerns: A 37-year-old male patient with an 8-month history of chronic lymphedema and ulcers of the lower left extremity presented with myiasis of the left foot and leg. The patient was initially seen by his family practitioner many times and was prescribed antibiotics which he could not afford. Debridement of the myiasis was not conducted by the family practitioner due to the belief that the patient's current state of myiasis would effectively debride and eventually heal the chronic ulcers along with multiple antibiotic regimens. Over the 8-month period, the patient developed a progressive, painful, necrotizing infection of his lower left extremity. Diagnoses: Physical examination clearly showed myiasis of the patient's lower left extremity, believed to be caused by Lucilia sericata (green bottle fly). Blood cultures revealed the presence of Providencia stuartii, W chitiniclastica, and I indica to be the underlying cause of sepsis and bacteremia. Interventions: All visible maggots were extracted, debridement of devitalized tissue was performed, and the leg ulcers were wrapped in pH neutral bleach. The patient was initially treated with a broad-spectrum antibiotic regimen of vancomycin, clindamycin, piperacillin, and tazobactam which, following clinical improvement, was de-escalated to cefepime. Outcomes: The fly larvae and maggots were removed from the extremity by scrubbing, pulse lavage, and filing away the callused tissue. Additionally, the patient's sepsis and bacteremia, caused by W chitiniclastica and I indica, were successfully treated through antibiotic intervention. Amputation was avoided. Lessons: The use of pulse lavage and chlorhexidine-soaked brushes for the removal of cavitary myiasis is an effective and minimally invasive procedure which does not cause additional damage to surrounding tissue. W chitiniclastica and I indica are emerging bacteria that have known association to parasitic fly myiasis in humans and are capable of causing sepsis and/or bacteremia if not accurately identified and treated promptly

The accumulation of Li2CO3 in a Li–O2 battery with dual mediators

One of the most important challenges facing long cycle life Li–O2 batteries is solvent degradation. Even the most stable ethers, such as CH3O(CH2CH2O)CH3, degrade to form products including Li2CO3, which accumulates in the pores of the gas diffusion electrode on cycling leading to polarisation and capacity fading. In this work, we examine the build-up and distribution of Li2CO3 within the porous gas diffusion electrode during cycling and its link to the cell failure. We also demonstrate that the removal of Li2CO3 by a redox mediator can partially recover the cell performance and extend the cycle life of a Li–O2 battery

The Kepler Pixel Response Function

Kepler seeks to detect sequences of transits of Earth-size exoplanets orbiting Solar-like stars. Such transit signals are on the order of 100 ppm. The high photometric precision demanded by Kepler requires detailed knowledge of how the Kepler pixels respond to starlight during a nominal observation. This information is provided by the Kepler pixel response function (PRF), defined as the composite of Kepler's optical point spread function, integrated spacecraft pointing jitter during a nominal cadence and other systematic effects. To provide sub-pixel resolution, the PRF is represented as a piecewise-continuous polynomial on a sub-pixel mesh. This continuous representation allows the prediction of a star's flux value on any pixel given the star's pixel position. The advantages and difficulties of this polynomial representation are discussed, including characterization of spatial variation in the PRF and the smoothing of discontinuities between sub-pixel polynomial patches. On-orbit super-resolution measurements of the PRF across the Kepler field of view are described. Two uses of the PRF are presented: the selection of pixels for each star that maximizes the photometric signal to noise ratio for that star, and PRF-fitted centroids which provide robust and accurate stellar positions on the CCD, primarily used for attitude and plate scale tracking. Good knowledge of the PRF has been a critical component for the successful collection of high-precision photometry by Kepler.Comment: 10 pages, 5 figures, accepted by ApJ Letters. Version accepted for publication

Investigation of the effect of sizing on the tensile and interface properties of continuous basalt fibre and polypropylene

The mechanical performance of continuous basalt fibres (BFs) and E-glass fibres (GFs) was investigated using single fibre tensile and microbond interface testing. Fibre surface topography was also studied, using atomic force microscopy. Continuous fibres of identical compositions with various surface sizings were used; interfacial shear strength was investigated using polypropylene (PP) matrix. Data were analysed alongside E-glass fibres with similar surface coatings. The tensile performance of basalt fibres varied significantly depending on the surface sizing applied at point of manufacture but little to no difference was found compared with the similarly sized E-glass fibres. The apparent interfacial shear strength (IFSS) between BFs and PP was significantly improved when sizing was applied. Both unsized BF and GF demonstrated very poor IFSS with PP but the application of silane to GFs produced a significantly greater improvement in the apparent adhesion. Characteristic differences in the surfaces of both unsized and silane-coated BFs and GFs were found by AFM analysis

From subject to fellow researcher: reconceptualising research relationships to safeguard potentially vulnerable survey participants

In this open peer commentary, we suggest that the dilemma encountered by Levinson et al. arises as a consequence of conceptual and practical decisions, which collectively, inappropriately dilute authority and accountability for survey data. We argue that it ma y be possible to reduce the ethical dilemmas encountered by Levinson et al., (2020) if not eliminate them entirely, by reconceptualising the inherent value of survey participants, their status and role in research. We suggest that when designing surveys, researchers should frame potential respondents as active collaborators and contributors of data, rather than merely as passive “subjects”. This shift in positioning delivers a conceptual foundation to proactively establish norms and expectations which respect participant privacy and anonymity, while safeguarding public safety

Micro-mechanical investigation of glass fibre/resin interface failure in mode I and mode II

Fibre reinforced composites are experiencing a period of consistent and significant growth which is predicted to continue, due to the sustained global increase in demand across a number of industrial sectors. One of the critical elements in the success of such composites in both the short and longer term is the interface/interphase between reinforcement fibres and matrix. Poor adhesion will generally lead to composites with insufficient mechanical performance. Degradation of the interface/interphase region during service life will lead to a decrease in performance, eventually to a point where the part can no longer fulfil its intended function. Micro-mechanical test methods can be an advantageous approach to analysing the fibre-matrix interface as they reduce material consumption and simplify the analysis compared with composites. In this paper some of the disadvantages of the commonly used microbond test are discussed, particularly difficulties related to testing of vinyl esters. A new micro-mechanical interface test is introduced which induces failure at the interface in mode I as opposed to the shear failure that occurs with microbond and several other contemporary interface tests

Influenza Vaccine Effectiveness against Hospitalisation with Confirmed Influenza in the 2010-11 Seasons: A Test-negative Observational Study

Immunisation programs are designed to reduce serious morbidity and mortality from influenza, but most evidence supporting the effectiveness of this intervention has focused on disease in the community or in primary care settings. We aimed to examine the effectiveness of influenza vaccination against hospitalisation with confirmed influenza. We compared influenza vaccination status in patients hospitalised with PCR-confirmed influenza with patients hospitalised with influenza-negative respiratory infections in an Australian sentinel surveillance system. Vaccine effectiveness was estimated from the odds ratio of vaccination in cases and controls. We performed both simple multivariate regression and a stratified analysis based on propensity score of vaccination. Vaccination status was ascertained in 333 of 598 patients with confirmed influenza and 785 of 1384 test-negative patients. Overall estimated crude vaccine effectiveness was 57% (41%, 68%). After adjusting for age, chronic comorbidities and pregnancy status, the estimated vaccine effectiveness was 37% (95% CI: 12%, 55%). In an analysis accounting for a propensity score for vaccination, the estimated vaccine effectiveness was 48.3% (95% CI: 30.0, 61.8%). Influenza vaccination was moderately protective against hospitalisation with influenza in the 2010 and 2011 seasons