Enhancement of exercise endurance capacity by fermented deer antler in BALB/c mice

To investigate the activity of fermented deer antler on exercise endurance capacity, we evaluated endurance capacity in five-week-old male BALB/c mice by administering the fermented deer antler extract (FA) or the non-fermented deer antler extract (NFA) and then subjected the mice to exercise in the form of swimming. The mice administered 500?mg/kg/day of FA showed a significant increase in swimming time compared with mice administered placebo (16.55?min vs. 21.64?min, P?<?0.05). Serum lactate dehydrogenase (LDH), the marker of the liver and muscle damage, was significantly lower in FA groups. However, NFA groups did not show significantly different swimming time or serum LDH from that of the control group. Moreover, the FA-500 group had significantly higher hepatic superoxide dismutase (SOD) activity after forced swimming than the control and NFA groups (P?<?0.05). These findings suggest that fermentation may increase the exercise endurance capacity of the deer antler.     

Drought‐induced xylem pit membrane damage in aspen and balsam poplar

Drought induces an increase in a tree's vulnerability to a loss of its hydraulic conductivity in many tree species, including two common in western Canada, trembling aspen (Populus tremuloides) and balsam poplar (Populus balsamifera). Termed ‘cavitation fatigue’ or ‘air‐seeding fatigue’, the mechanism of this phenomenon is not well understood, but hypothesized to be a result of damage to xylem pit membranes. To examine the validity of this hypothesis, the effect of drought on the porosity of pit membranes in aspen and balsam poplar was investigated. Controlled drought and bench dehydration treatments were used to induce fatigue and scanning electron microscopy (SEM) was used to image pit membranes for relative porosity evaluations from air‐dried samples after ethanol dehydration. A significant increase in the diameter of the largest pore was found in the drought and dehydration treatments of aspen, while an increase in the percentage of porous pit membranes was found in the dehydration treatments of both species. Additionally, the location of the largest pore per pit membrane was observed to tend toward the periphery of the membrane.     

Direct observation and modelling of embolism spread between xylem conduits: a case study in Scots pine

Xylem embolism is one of the main processes involved in drought‐related plant mortality. Although its consequences for plant physiology are already well described, embolism formation and spread are poorly evaluated and modelled, especially for tracheid‐based species. The aim of this study was to assess the embolism formation and spread in Pinus sylvestris as a case study using X‐ray microtomography and hydraulics methods. We also evaluated the potential effects of cavitation fatigue on vulnerability to embolism and the micro‐morphology of the bordered pits using scanning electron microscopy (SEM) to test for possible links between xylem anatomy and embolism spread. Finally, a novel model was developed to simulate the spread of embolism in a 2D anisotropic cellular structure. Results showed a large variability in the formation and spread of embolism within a ring despite no differences being observed in intertracheid pit membrane anatomical traits. Simulations from the model showed a highly anisotropic tracheid‐to‐tracheid embolism spreading pattern, which confirms the major role of tracheid‐to‐tracheid air seeding to explain how embolism spreads in Scots pine. The results also showed that prior embolism removal from the samples reduced the resistance to embolism of the xylem and could result in overestimates of vulnerability to embolism.     

Limitations of a morphological criterion of adaptive inference in the fossil record

Experimental analyses directly inform how an anatomical feature or complex functions during an organism's lifetime, which serves to increase the efficacy of comparative studies of living and fossil taxa. In the mammalian skull, food material properties and feeding behaviour have a pronounced influence on the development of the masticatory apparatus. Diet‐related variation in loading magnitude and frequency induce a cascade of changes at the gross, tissue, cellular, protein and genetic levels, with such modelling and remodelling maintaining the integrity of oral structures vis‐à‐vis routine masticatory stresses. Ongoing integrative research using rabbit and rat models of long‐term masticatory plasticity offers unique insight into the limitations of functional interpretations of fossilised remains. Given the general restriction of the palaeontological record to bony elements, we argue that failure to account for the disparity in the hierarchical network of responses of hard versus soft tissues may overestimate the magnitude of the adaptive divergence that is inferred from phenotypic differences. Second, we note that the developmental onset and duration of a loading stimulus associated with a given feeding behaviour can impart large effects on patterns of intraspecific variation that can mirror differences observed among taxa. Indeed, plasticity data are relevant to understanding evolutionary transformations because rabbits raised on different diets exhibit levels of morphological disparity comparable to those found between closely related primate species that vary in diet. Lastly, pronounced variation in joint form, and even joint function, can also characterise adult conspecifics that differ solely in age. In sum, our analyses emphasise the importance of a multi‐site and hierarchical approach to understanding determinants of morphological variation, one which incorporates critical data on performance.     

Does the circadian clock drift when pilots fly multiple transpacific flights with 1- to 2-day layovers?

On trips with multiple transmeridian flights, pilots experience successive non-24 h day/night cycles with circadian and sleep disruption. One study across a 9-day sequence of transpacific flights (no in-flight sleep, 1-day layovers between flights) reported an average period in the core body temperature rhythm of 24.6 h (circadian drift). Consequently, pilots were sometimes flying through the circadian performance nadir and had to readapt to home base time at the end of the trip. The present study examined circadian drift in trip patterns with longer flights and in-flight sleep. Thirty-nine B747-400 pilots (19 captains, 20 first officers, mean age = 55.5 years) were monitored on 9- to 13-day trips with multiple return flights between East Coast USA and Japan (in 4-pilot crews) and between Japan and Hawaii (in 3-pilot crews), with 1-day layovers between each flight. Measures included total in-flight sleep (actigraphy, log books) and top of descent (TOD) measures of sleepiness (Karolinska Sleepiness Scale), fatigue (Samn–Perelli Crew Status Check) and psychomotor vigilance task (PVT) performance. Circadian rhythms of individual pilots were not monitored. To detect circadian drift, mixed-model analysis of variance examined whether for a given flight, total in-flight sleep and TOD measures varied according to when the flight occurred in the trip sequence. In addition, sleep propensity curves for pre-trip and post-trip days were examined (Chi-square periodogram analyses). Limited data suggest that total in-flight sleep of relief crew at landing may have decreased across successive East Coast USA–Japan (flights 1, 3, 5 or 7; median arrival 03:45 Eastern Daylight Time (EDT)). However, PVT response speed at TOD was faster on East Coast USA–Japan flights later in the trip. On these flights, circadian drift would result in flights later in the trip landing closer to the evening wake maintenance zone, when sleep is difficult and PVT response speeds are fastest. On Japan–East Coast USA flights (flights 2, 4, 6 or 8; median arrival time 14:52 EDT), PVT response speeds were slower on flight 8 than on flight 2. Circadian drift would move these arrivals progressively earlier in the SCN pacemaker cycle, where PVT response speeds are slower. Across the five post-trip days, 12 pilots (Group A) immediately resumed their pre-trip sleep pattern of a single nocturnal sleep episode; 9 pilots (Group B) had a daytime nap on most days that moved progressively earlier until it merged with nocturnal sleep and 17 pilots (Group C) had nocturnal sleep and intermittent naps. Chi-square periodogram analyses of the sleep propensity curves for each group across baseline and post-trip days suggest full adaptation to EDT from post-trip day 1 (dominant period = 24 h). However, in Groups B and C, the patterns of split sleep post-trip compared to pre-trip suggest that this may be misleading. We conclude that the trends in total in-flight sleep and significant changes in PVT performance speed at TOD provide preliminary evidence for circadian drift, as do persistent patterns of split sleep post-trip. However, new measures to track circadian rhythms in individual pilots are needed to confirm these findings.     

Numerical investigations of rib fracture failure models in different dynamic loading conditions

Rib fracture is one of the most common thoracic injuries in vehicle traffic accidents that can result in fatalities associated with seriously injured internal organs. A failure model is critical when modelling rib fracture to predict such injuries. Different rib failure models have been proposed in prediction of thorax injuries. However, the biofidelity of the fracture failure models when varying the loading conditions and the effects of a rib fracture failure model on prediction of thoracic injuries have been studied only to a limited extent. Therefore, this study aimed to investigate the effects of three rib failure models on prediction of thoracic injuries using a previously validated finite element model of the human thorax. The performance and biofidelity of each rib failure model were first evaluated by modelling rib responses to different loading conditions in two experimental configurations: (1) the three-point bending on the specimen taken from rib and (2) the anterior–posterior dynamic loading to an entire bony part of the rib. Furthermore, the simulation of the rib failure behaviour in the frontal impact to an entire thorax was conducted at varying velocities and the effects of the failure models were analysed with respect to the severity of rib cage damages. Simulation results demonstrated that the responses of the thorax model are similar to the general trends of the rib fracture responses reported in the experimental literature. However, they also indicated that the accuracy of the rib fracture prediction using a given failure model varies for different loading conditions.     

When mental fatigue maybe characterized by Event Related Potential (P300) during virtual wheelchair navigation

The goal of this study is to investigate the influence of mental fatigue on the event related potential P300 features (maximum pick, minimum amplitude, latency and period) during virtual wheelchair navigation. For this purpose, an experimental environment was set up based on customizable environmental parameters (luminosity, number of obstacles and obstacles velocities). A correlation study between P300 and fatigue ratings was conducted. Finally, the best correlated features supplied three classification algorithms which are MLP (Multi Layer Perceptron), Linear Discriminate Analysis and Support Vector Machine. The results showed that the maximum feature over visual and temporal regions as well as period feature over frontal, fronto-central and visual regions were correlated with mental fatigue levels. In the other hand, minimum amplitude and latency features didn’t show any correlation. Among classification techniques, MLP showed the best performance although the differences between classification techniques are minimal. Those findings can help us in order to design suitable mental fatigue based wheelchair control.     

Adaptations to isolated shoulder fatigue during simulated repetitive work. Part I: Fatigue

Upper extremity muscle fatigue is challenging to identify during industrial tasks and places changing demands on the shoulder complex that are not fully understood. The purpose of this investigation was to examine adaptation strategies in response to isolated anterior deltoid muscle fatigue while performing simulated repetitive work. Participants completed two blocks of simulated repetitive work separated by an anterior deltoid fatigue protocol; the first block had 20 work cycles and the post-fatigue block had 60 cycles. Each work cycle was 60 s in duration and included 4 tasks: handle pull, cap rotation, drill press and handle push. Surface EMG of 14 muscles and upper body kinematics were recorded. Immediately following fatigue, glenohumeral flexion strength was reduced, rating of perceived exertion scores increased and signs of muscle fatigue (increased EMG amplitude, decreased EMG frequency) were present in anterior and posterior deltoids, latissimus dorsi and serratus anterior. Along with other kinematic and muscle activity changes, scapular reorientation occurred in all of the simulated tasks and generally served to increase the width of the subacromial space. These findings suggest that immediately following fatigue people adapt by repositioning joints to maintain task performance and may also prioritize maintaining subacromial space width.     

Surface Engineering of 3D Gas Diffusion Electrodes for High‐Performance H2 Production with Nonprecious Metal Catalysts

In this work, a methodology is demonstrated to engineer gas diffusion electrodes for nonprecious metal catalysts. Highly active transition metal phosphides are prepared on carbon‐based gas diffusion electrodes with low catalyst loadings by modifying the O/C ratio at the surface of the electrode. These nonprecious metal catalysts yield extraordinary performance as measured by low overpotentials (51 mV at ?10 mA cm^?2), unprecedented mass activities (>800 A g^?1 at 100 mV overpotential), high turnover frequencies (6.96 H₂ s^?1 at 100 mV overpotential), and high durability for a precious metal‐free catalyst in acidic media. It is found that a high O/C ratio induces a more hydrophilic surface directly impacting the morphology of the CoP catalyst. The improved hydrophilicity, stemming from introduced oxyl groups on the carbon electrode, creates an electrode surface that yields a well‐distributed growth of cobalt electrodeposits and thus a well‐dispersed catalyst layer with high surface area upon phosphidation. This report demonstrates the high‐performance achievable by CoP at low loadings which facilitates further cost reduction, an important part of enabling the large‐scale commercialization of non‐platinum group metal catalysts. The fabrication strategies described herein offer a pathway to lower catalyst loading while achieving high efficiency and promising stability on a 3D electrode.     

Localized High‐Concentration Electrolytes Boost Potassium Storage in High‐Loading Graphite

Reversible intercalation of potassium‐ion (K⁺) into graphite makes it a promising anode material for rechargeable potassium‐ion batteries (PIBs). However, the current graphite anodes in PIBs often suffer from poor cyclic stability with low coulombic efficiency. A stable solid electrolyte interphase (SEI) is necessary for stabilizing the large interlayer expansion during K⁺ insertion. Herein, a localized high‐concentration electrolyte (LHCE) is designed by adding a highly fluorinated ether into the concentrated potassium bis(fluorosulfonyl)imide/dimethoxyethane, which forms a durable SEI on the graphite surface and enables highly reversible K⁺ intercalation/deintercalation without solvent cointercalation. Furthermore, this LHCE shows a high ionic conductivity (13.6 mS cm^?1) and excellent oxidation stability up to 5.3 V (vs K⁺/K), which enables compatibility with high‐voltage cathodes. The kinetics study reveals that K⁺ intercalation/deintercalation does not follow the same pathway. The potassiated graphite exhibits excellent depotassiation rate capability, while the formation of a low stage intercalation compound is the rate‐limiting step during potassiation.