Small changes in thermal conditions hinder marathon running performance in the tropics

This is the final version. Available on open access from Routledge via the DOI in this recordWe examined marathon performance of the same group of runners in relation to small changes in dry bulb temperature (Tdb) and wet bulb temperature (Twb) across three consecutive years, and investigated whether performance was poorer during an evening marathon compared with morning marathons. Marathon results were obtained from the 2017, 2018 and 2019 Standard Chartered Singapore Marathons. Tdb, Twb, Td, relative humidity and absolute humidity were gathered for each marathon. Kmeans clustering and linear regressions were performed on 610 runners who participated in all three marathons. Analysis of the 610 runners’ marathon performance was contrasted with Tdb and Twb. Linear regressions were also performed on 190 runners filtered by percentile, yielding similar results. For clusters with similar Tdb from all runners K-means clustering, an increase in mean Twb by 1.5℃ coincided with an increase in finishing time by 559 s (9.3 min) (p < 0.033). Twb hinders marathon performance more than Tdb, with each percentage rise in Tdb and Twb resulting in an increase in net time by 7.6% and 39.1% respectively (p < 0.025). Male and female runners’ response to Tdb and Twb changes were similar (overlap in 95% confidence intervals for the respective regression coefficients). In conclusion, small variations in environmental parameters affected marathon performance, with Twb impairing marathon performance more than Tdb. Marathon performance was likely better in the morning than evening, possibly due to time of day differences, along with unfavourable Tdb that superseded training effects and the effects of lower Twb

Nanofiber fabrication in a temperature and humidity controlled environment for improved fibre consistency

To fabricate nanofibers with reproducible characteristics, an important demand for many applications, the effect of controlled atmospheric conditions on resulting electrospun cellulose acetate (CA) nanofibers was evaluated for temperature ranging 17.5 - 35&#xb0;C and relative humidity ranging 20% - 70%. With the potential application of nanofibers in many industries, especially membrane and filter fabrication, their reproducible production must be established to ensure commercially viability.&#xd;&#xa;Cellulose acetate (CA) solution (0.2 g/ml) in a solvent mixture of acetone/DMF/ethanol (2:2:1) was electrospun into nonwoven fibre mesh with the fibre diameter ranging from 150nm to 1&#xb5;m.&#xd;&#xa;The resulting nanofibers were observed and analyzed by scanning electron microscopy (SEM), showing a correlation of reducing average fibre diameter with increasing atmospheric temperature. A less pronounced correlation was seen with changes in relative humidity regarding fibre diameter, though it was shown that increased humidity reduced the effect of fibre beading yielding a more consistent, and therefore better quality of fibre fabrication.&#xd;&#xa;Differential scanning calorimetry (DSC) studies observed lower melt enthalpies for finer CA nanofibers in the first heating cycle confirming the results gained from SEM analysis. From the conditions that were explored in this study the temperature and humidity that gave the most suitable fibre mats for a membrane purpose were 25.0&#xb0;C and 50%RH due to the highest level of fibre diameter uniformity, the lowest level of beading while maintaining a low fibre diameter for increased surface area and increased pore size homogeneity. This study has highlighted the requirement to control the atmospheric conditions during the electrospinning process in order to fabricate reproducible fibre mats

A Novel, Stable, Estradiol-Stimulating, Osteogenic Yam Protein with Potential for the Treatment of Menopausal Syndrome

A novel protein, designated as DOI, isolated from the Chinese yam (Dioscorea opposita Thunb.) could be the first protein drug for the treatment of menopausal syndrome and an alternative to hormone replacement therapy (HRT), which is known to have undesirable side effects. DOI is an acid- and thermo-stable protein with a distinctive N-terminal sequence Gly-Ile-Gly-Lys-Ile-Thr-Thr-Tyr-Trp-Gly-Gln-Tyr-Ser-Asp-Glu-Pro-Ser-Leu-Thr-Glu. DOI was found to stimulate estradiol biosynthesis in rat ovarian granulosa cells; induce estradiol and progesterone secretion in 16- to 18-month-old female Sprague Dawley rats by upregulating expressions of follicle-stimulating hormone receptor and ovarian aromatase; counteract the progression of osteoporosis and augment bone mineral density; and improve cognitive functioning by upregulating protein expressions of brain-derived neurotrophic factor and TrkB receptors in the prefrontal cortex. Furthermore, DOI did not stimulate the proliferation of breast cancer and ovarian cancer cells, which suggest it could be a more efficacious and safer alternative to HRT.link_to_OA_fulltex

Microstructural evolution and trace element mobility in Witwatersrand pyrite

Microstructural analysis of pyrite from a single sample of Witwatersrand conglomerate indicates a complex deformation history involving components of both plastic and brittle deformation. Internal deformation associated with dislocation creep is heterogeneously developed within grains, shows no systematic relationship to bulk rock strain or the location of grain boundaries and is interpreted to represent an episode of pyrite deformation that predates the incorporation of detrital pyrite grains into the Central Rand conglomerates. In contrast, brittle deformation, manifest by grain fragmentation that transects dislocation-related microstructures, is spatially related to grain contacts and is interpreted to represent post-depositional deformation of the Central Rand conglomerates. Analysis of the low-angle boundaries associated with the early dislocation creep phase of deformation indicates the operation of {100} slip systems. However, some orientation boundaries have geometrical characteristics that are not consistent with simple {100} deformation.These boundaries may represent the combination of multiple slip systems or the operation of the previously unrecognized {120} slip system. These boundaries are associated with order of magnitude enrichments in As, Ni and Co that indicate a deformation control on the remobilization of trace elements within pyrite and a potential slip system control on the effectiveness of fast-diffusion pathways. The results confirm the importance of grain-scale elemental remobilization within pyrite prior to their incorporation into the Witwatersrand gold-bearing conglomerates. Since the relationship between gold and pyrite is intimately related to the trace element geochemistry of pyrite, the results have implications for the application of minor element geochemistry to ore deposit formation, suggest a reason for heterogeneous conductivity and localized gold precipitation in natural pyrite and provide a framework for improving mineral processing

The effects of low and normal dose ice slurry ingestion on endurance capacity and intestinal epithelial injury in the heat

10.1016/j.jsams.2023.04.008Journal of Science and Medicine in Sport266278-28

Photochromic diarylethene-containing ionic liquids and N-heterocyclic carbenes

The design and synthesis of a series of photochromic diarylethene- containing Arduengo-type N-heterocyclic carbenes (NHCs) of gold(I), silver(I) and palladium(II) and their imidazolium salt precursors are reported. Reversible photochromic behavior was observed. The open form and the closed form also show different luminescence properties. The electronic and conformational/steric changes associated with the photocyclization and photocycloreversion reactions may open up new opportunities for the discovery of new classes of photochromic ligands and metal-containing materials and catalysts with photoswitchable functions and activities and regio-/enantioselectivities. Copyright © 2009 American Chemical Society.link_to_subscribed_fulltex

Steroidogenic effect of Erxian decoction for relieving menopause via the p-Akt/PKB pathway in vitro and in vivo

Poster Session - no. P155Erxian decoction (EXD), an empirical Chinese medicine formula, is clinically used for menopause in China. Previous data from our group revealed that EXD possesses steroidogenic effect on natural menopausal Sprague-Dawley-rats (SD-rats). However, the mechanistic studies on steroidogenic effects of EXD are still inadequate. Hence, the mechanisms of steroidogenic effects of EXD were studied in vitro and in vivo in this study. Menopause causes a decline of endocrine function and a series of symptoms. In this study, 16-20-month-old female SD rats with a low serum estradiol level were employed. Their endocrine functions after treatment with EXD (4.1g/kg) were assessed by determination of their serum estradiol level. Proteins involved in the steroidogenic pathway including StAR, 17βHSD, 3βHSD, aromatase, and activation of phosphorylated Protein Kinase B (p-Akt/PKB), as well as estradiol receptor proteins (ERα & ERβ) after EXD treatment were analyzed. Kinase inhibition assay was conducted to confirm the mechanism of steroidogenic effects of EXD in vitro. MCF-7 and BT-483 breast cancer cells were used to investigate whether EXD stimulated breast cancer cell proliferation. Results revealed a significantly ameliorated serum estradiol level, and a significantly increased expression of ovarian aromatase and PKB in the EXD-treated rats. EXD attenuated 17β-estradiol stimulated proliferation of breast cancer cells. The results obtained from immunoblotting and measurements of serum estradiol level of the present investigation revealed that EXD may relieve the menopausal syndrome through an upregulation of ovarian aromatase and p-PKB expression without stimulating the growth of breast cancer cells