Development of the ASTM E681 Standard

ASHRAE 34, based on ASTM E681, was improved by identifying and rectifying deficiencies in ASTM E681. An ASTM E681 apparatus and procedure was developed with gaseous refrigerant testing in mind. The plumbing was improved by ensuring that the pressure readings could be constantly monitored while decreasing leakage potential. An original electrical system was designed and constructed for the ignition system. Additionally, a control panel was constructed to isolate hazardous electrical elements, and facilitate the testing, while simultaneously organizing the critical plumbing and ignition components. 3D printing efficiently produced heat-resistant, nonreactive, and structurally stable lower electrode spacers, propellers, and propeller bars. The heating system was designed to ensure even temperature throughout the apparatus. The humidity system was designed to accurately condition the air. Recommendations to improve ASTM E681 are provided. The research can be built on to improve the accuracy and reproducibility of ASTM E681

Base excision repair processing of abasic site/single-strand break lesions within clustered damage sites associated with XRCC1 deficiency

Ionizing radiation induces clustered DNA damage, which presents a challenge to the cellular repair machinery. The repair efficiency of a single-strand break (SSB) is ∼4× less than that for repair of an abasic (AP) site when in a bistranded cluster containing 8-oxoG. To explore whether this difference in repair efficiency involves XRCC1 or other BER proteins, synthetic oligonucleotides containing either an AP site or HAP1-induced SSB (HAP1-SSB) 1 or 5 bp 5′ or 3′ to 8-oxoG on the opposite strand were synthesized and the repair investigated using either nuclear extracts from hamster cells proficient (AA8) or deficient (EM7) in XRCC1 or purified BER proteins. XRCC1 is important for efficient processing of an AP site in clustered damage containing 8-oxoG but does not affect the already low repair efficiency of a SSB. Ligase I partly compensates for the absence of the XRCC1/ligaseIII during short-patch BER of an AP site when in a cluster but only weakly if at all for a HAP1-SSB. The major difference between the repair of an AP site and a HAP1-SSB when in a 8-oxoG containing cluster is the greater efficiency of short-patch BER with the AP site compared with that for a HAP1-SSB

Impact of weekly swimming training distance on the ergogenicity of inspiratory muscle training in well trained youth swimmers.

The aim of this study was to examine the impact of weekly swimming training distance upon the ergogenicity of inspiratory muscle training (IMT). Thirty-three youth swimmers were recruited and separated into a LOW and HIGH group based on weekly training distance ( 41 km.wk-1, respectively). The LOW and HIGH groups were further subdivided into control and IMT groups for a 6-week IMT intervention giving a total of four groups: LOWcon, LOWIMT, HIGHcon, HIGHIMT. Before and after the intervention period, swimmers completed maximal effort 100 m and 200 m front crawl swims, with maximal inspiratory and expiratory mouth pressures (PImax and PEmax, respectively) assessed before and after each swim. IMT increased PImax (but not PEmax) by 36% in LOWIMT and HIGHIMT groups (P < 0.05) but 100 m and 200 m swims were faster only in the LOWIMT group (3% and 7% respectively, P < 0.05). Performance benefits only occurred in those training up to 31 km.wk-1 and indicate that the ergogenicity of IMT is affected by weekly training distance. Consequently, training distances are important considerations, among others, when deciding whether or not to supplement swimming training with IMT.N/

Tracking the stochastic growth of bacterial populations in microfluidic droplets

Bacterial growth in microfluidic droplets is relevant in biotechnology, in microbial ecology, and in understanding stochastic population dynamics in small populations. However, it has proved challenging to automate measurement of absolute bacterial numbers within droplets, forcing the use of proxy measures for population size. Here we present a microfluidic device and imaging protocol that allows high-resolution imaging of thousands of droplets, such that individual bacteria stay in the focal plane and can be counted automatically. Using this approach, we track the stochastic growth of hundreds of replicate Escherichia coli populations within droplets. We find that, for early times, the statistics of the growth trajectories obey the predictions of the Bellman-Harris model, in which there is no inheritance of division time. Our approach should allow further testing of models for stochastic growth dynamics, as well as contributing to broader applications of droplet-based bacterial culture

SPAMCART: a code for smoothed particle Monte Carlo radiative transfer

We present a code for generating synthetic SEDs and intensity maps from Smoothed Particle Hydrodynamics simulation snapshots. The code is based on the Lucy (1999) Monte Carlo Radiative Transfer method, i.e. it follows discrete luminosity packets as they propagate through a density field, and then uses their trajectories to compute the radiative equilibrium temperature of the ambient dust. The sources can be extended and/or embedded, and discrete and/or diffuse. The density is not mapped onto a grid, and therefore the calculation is performed at exactly the same resolution as the hydrodynamics. We present two example calculations using this method. First, we demonstrate that the code strictly adheres to Kirchhoff's law of radiation. Second, we present synthetic intensity maps and spectra of an embedded protostellar multiple system. The algorithm uses data structures that are already constructed for other purposes in modern particle codes. It is therefore relatively simple to implement

Improving Refrigerant Flammability Limit Test Methods Based on ASTM E681

An improved test method for refrigerant flammability limit measurements is presented. Such measurements are essential for determining the lower flammability limits of refrigerants, and thus their safety classifications. Predicated on expert interviews and experiments, several changes to ASTM E681 and related standards are recommended, as follows. The 12 L glass vessel should be replaced with transparent polycarbonate (or other transparent plastic) to eliminate etching by HF and to facilitate vessel penetrations. The orientation of the electrode supports and the temperature probe should be changed from vertical to horizontal to prevent flame quenching. Venting should not occur before the flame stops propagating near the vessel wall. All penetrations should be removed from the rubber stopper, it should be weighted for a total mass of 2.5 kg, and the initial pressure should be 90 kPa absolute. The flame angle should be plotted versus refrigerant concentration, whereby a least-squares line determines the flammability limit at a flame angle of 90°. Finally, the vessel pressure should be measured during each test to evaluate the pressure rise during flame propagation and to help identify the onset of venting. These changes are relatively easy to implement and they improve the test precision and reproducibility without significantly changing previously established flammability limits