High Load Conditions Research Articles

Modeling teachers’ reactions to unexpectedness

BackgroundEven experienced teachers make inconsistent classroom decisions in unexpected situations. From the cognitive load theory perspective, the effective handling of the novel, unexpected events by teachers depends on the cognitive load of the task, the teaching context in which the unexpectedness appears, and the available cognitive capacity. AimsTeachers’ reactions to unexpected mathematical events, in particular the unexpectedness of the arithmetic calculation, was modeled, investigated experimentally, and explained within the theoretical framework of cognitive load theory. Sample64 mathematics teacher trainees took part in the experiment. MethodsIn a dual-task arrangement, participants verified alternative answers to simple mathematical questions while memorizing task-irrelevant information. The answers represented low (schematic good responses), and high (unexpected good responses) processing load conditions, and control condition (incorrect responses). The memory load was low or high representing levels of extraneous load. The participants’ cognitive capacity was estimated by a complex working memory span task. ResultsThe verification of unexpected but correct answers was slow and more error-prone as compared with the processing speed and accuracy of schematic answers, presumably due to elevated processing (intrinsic) load. The increase in memory load resulted in slower and more inaccurate verifications. However, working memory capacity was found to mediate the extraneous load effect. ConclusionsThe results stress the importance of well-organized schemas for effective reactions to unexpected classroom events. Furthermore, it highlights the importance of accurately understanding and being aware of the impact of cognitive load on teachers to improve teaching practice.

Prediction of the Engine Performance and Emission Characteristics of Glycine Max Biodiesel Blends With Nanoadditives and Hydrogen

Abstract This study investigates the Glycine max (soybean oil) biodiesel with hydrogen along with MgO nanoadditives on compression ignition engines. A series of tests were conducted at various loading conditions in a water-cooled, single-cylinder, constant-speed engine. The biodiesel-blended soya oil was used as the primary fuel, and hydrogen was added at a constant volume of 25 LPM. Additionally, MgO nanoparticles were dispersed to the blends at concentrations of 50 ppm. In this study, it was found that the addition of hydrogen to the compression ignition (CI) engine resulted in an increase in combustion performance. In addition, hydrogen and oxygen molecules significantly reduced the exhaust gas temperature and brake-specific fuel consumption of biodiesel samples. An increase in nanoparticle concentration resulted in a reduction in emissions of pollutants such CO2, CO, and HC. Inclusion of the hydrogen in the combustion chamber reduces the carbon content burned. Further, the availability of extra molecules in the MgO aids the fuel to reach higher combustion rates. At higher load conditions, biodiesel blends showed a slight decrease in NOx emissions. Overall, from the findings, it is clear that hydrogen addition and nanoparticles enhanced emission and combustion process, which is attributed due to the increase in hydrogen content in the fuel.

Reactive plasma-sprayed TiNx incorporation in Fe-based amorphous coatings for enhancing mechanics properties and ameliorating tribological performance

An in-situ TiNx-reinforced Fe-based amorphous composite coating was fabricated by reactive plasma-spraying. Moreover, well formed TiNx exhibited excellent bonding interface with the amorphous. Besides, the composite coating displayed higher microhardness and resistance to plastic deformation compared to unadulterated amorphous coatings. Additionally, the composite coating reformed the smooth-stepped brittle fracture morphology of the amorphous coating, due to the hindered expansion of cracks between the two phases. Furthermore, delamination, oxidation, and other negative wear phenomena of the amorphous coating were effectively improved in the composite coating, especially under high load and high-speed friction conditions. The integration of TiNx had a significant positive effect on improving the friction-induced crack damage of Fe-based amorphous coatings, thus, the wear resistance.

The effect of pure methane energy fraction on combustion performance, energy analysis and environmental - economic cost indicators in a single-cylinder common rail methane-diesel dual fuel engine

Although methane-diesel dual fuel implementation is a very effective method in reducing high NOx and smoke emissions, which are the main problems of diesel engines, this implementation still suffers from high level of HC and CO emissions at low-medium load conditions. Considering this problem of dual-fuel engines, it is very important to examine the effects of pollutant emissions resulting from combustion on the environment and human health to see the usability of methane gas in dual fuel mode, and the current literature is quite limited. Therefore, in this study, the effect of methane energy fraction on combustion, emissions and environmental-economic costs was investigated in a dual fuel engine with optimum diesel injection timing.The tests were conducted in a single-cylinder, air-cooled, common rail diesel engine at constant engine speed and variable engine loads. The operation was carried out in two different modes as diesel and methane-diesel dual fuel. In the first mode, the optimum diesel injection timing of common rail diesel engine was determined. Five different injection timings from 11°CA to 19°CA before top dead center (bTDC) were used to determine the optimum diesel injection timing. The second mode was carried out at varying methane energy fraction (MEF) levels with %0, %25, and %50 contributions to the total fuel energy of methane. In the optimum injection timing experiments, the lowest ignition delay period, combustion duration, lower emission values, and better engine performance were obtained with 11°CA bTDC under all load conditions. The methane energy fraction significantly reduced the maximum combustion pressure, especially under low load conditions. However, combustion pressure values of diesel and methane-diesel dual fuel studies under high load conditions were obtained close to each other due to late injection timing, high injection pressure, and higher combustion temperature. Moreover, COVIMEP values of all test fuels were obtained below 5% under medium and high load conditions. On the other hand, NO and smoke emissions, which are the main problems of diesel engines, decreased significantly. With the increase of MEF level in methane-diesel dual fuel application, NO emissions showed an improvement up to 67%. Similarly, smoke emissions improved up to 82%. Despite the high HC and CO emissions, which is one of the main problems of the dual fuel mode, the significant reduction of NO emissions due to methane addition has significantly improved the environmental and economic costs. This situation clearly demonstrated the usability of high methane substitution in terms of emissions in dual fuel mode. In addition, exhaust energy loss for all load conditions in methane-diesel dual fuel mode showed an average improvement of 13.5% compared to diesel mode. As a result, high methane substitution is promising because it significantly reduces NO and smoke emissions, which are the main problems of diesel engines, and the low-performance data is at a compensable level.

Effect of strain rate on mechanical response and failure characteristics of horizontal bedded coal under quasi-static loading

Strain rock burst is one of the main types of rock bursts. Studying the mechanical response and acoustic emission characteristics of coal under quasi-static loading is significant to control and prevent strain rock bursts. In this paper, coal’s strength, deformation, energy evolution, and failure characteristics were analyzed with different strain rates under quasi-static loading. The strength characteristics of coal show a strain rate effect to a certain extent and the elastic modulus decreases first and then increases with stain rate increasing. Moreover, the elastic strain energy of coal samples always accounts for a high proportion before failure and the failure of coal presents a combined failure mode of tensile and shear under the dominance of tensile failure. The contribution of the shear failure to coal failure increases correspondingly when strain rate increases. Under quasi-static loading, There is a range where the strain rate effect does not appear, named as strain rate effect invisible area. The high static loading stress, and direct action of high strain rate loading should be avoided to reduce the risk of rock burst, especially for isolated coal pillars. The research achievements deepen the understanding of strain rock burst and provides critical support for the prevention of strain rock burst induced by high static loading.

Graphitic carbon nitride quantum dots as novel and efficient friction-reduction and anti-wear additives for water-based lubrication

Undeniably, advances in water-based nano-additives play a considerable role in energy conservation and pollution reduction accompanied by the resurgence of water-based lubricants. Graphitic carbon nitride quantum dots (g-CNQDs) have attracted remarkable attention in water-based lubricant additives owing to their strong designability, favorable mechanical property, and unique self-lubricating effect. Therefore, a series of different-sized g-CNQDs with good water dispersibility were expediently synthesized via a hydrothermal strategy and directly used as water-based lubricant additives. Tribological tests indicated that the tribological behaviors of the g-CNQDs-based additives displayed an obvious phenomenon of performance-dependent physical dimensions. With the introduction of g-CNQDs-based additives (1.0 wt%) into the water-based lubrication system, which friction-reduction, anti-wear, and load-supporting performances can be maximally increased by 45.5%, 94.0%, and 233.3%, respectively. Meanwhile, the long-term operating performance of the lubrication system can be promoted under high-load conditions. The formed tribo-film caused by tribo-chemical reaction integrated with the nano-lubrication effect of g-CNQDs collectively contributed to their good tribological performances.

Diagonal compression testing of masonry under fatigue loading and high static loads

Underground railway operations pose a significant impact on overlying, highly sensitive historic masonry structures. Here, the process of structural assessment involves fatigue actions, through induced ground-borne vibrations, from operating underground railways. Considering long-term exposure periods, fatigue can introduce local cracking and losses, which endanger the integrity of both structural and non-structural elements. The lack of experimental fatigue data on tensile actions in masonry and the apparent computational restraints from constitutive cementitious material models that do not account for damage due to repeated loading, increase the complexity of structural assessment, under combined fatigue actions and other hazards. The current paper aims at providing new experimental data on fatigue in historic brick and lime mortar masonry wallets, replicating realistic combinations of static and fatigue loading under diagonal compression. Material deterioration and stiffness degradation are monitored throughout the process. Hence, under moderate amplitudes of fatigue loading and high static loads, cracking occurred, at a relatively low number of cycles, demonstrating the need for more strict vibration thresholds to ensure the integrity of historic masonry buildings.

Effects of Pre-spark Heat Release of Ethanol-Blended Gasoline Surrogate Fuels on Engine Combustion Behavior

<div>Regulations limiting greenhouse gas (GHG) emissions in the transport sector have become more restrictive in recent years, drawing interest to synthetic fuels such as e-fuels and biofuels that could “decarbonize” existing vehicles. This study focuses on the potential to increase the thermal efficiency of spark-ignition (SI) engines using ethanol as a renewable fuel, which requires a deep understanding of the effects of ethanol on combustion behavior with high compression ratios (CRs). An important phenomenon in this condition is pre-spark heat release (PSHR), which occurs in engines with high CRs in boosted conditions and changes the fuel reactivity, leading to changes in the burning velocity. Fuel blends containing ethanol display high octane sensitivity (OS) and limited low-temperature heat release (LTHR). Consequently, their burning velocities with PSHR may differ from that of gasoline. This study therefore aimed to clarify the effects of ethanol on SI combustion behavior under PSHR conditions. Combustion behavior was studied by performing single-cylinder engine experiments and chemical kinetics simulations. The experimental measurements were performed to characterize the relationship between the occurrence of PSHR and the main combustion duration. Analysis of this relationship showed that the ethanol-blended fuel has a lesser PSHR and a longer combustion duration than the non-ethanol fuel by approximately 5% in high engine load conditions. Simulations using input data from the experiments revealed that the ethanol-blended fuel has a lower laminar burning velocity due to the lower temperature in the unburned mixture caused by its PSHR. Additional simulations examining the chemical effect of partially oxidized reactants caused by PSHR on the laminar burning velocity showed that partially oxidized reactants increase the laminar burning velocity of the ethanol-blended fuel but decrease that of a reference fuel without ethanol. A large number of fuel radicals and oxides of the ethanol-blended fuel enhances chain-branching reactions in the pre-flame zone and possibly increases its laminar burning velocity. However, the thermodynamic effect of PSHR on laminar burning velocity exceeds the chemical effect, and thus the ethanol-blended fuel has a lower turbulent burning velocity in the PSHR conditions.</div>

An Energy-Efficient DL-Aided Massive Multiple Access Scheme for IoT Scenarios in Beyond 5G Networks

In view of the challenges foreseen in futuristic massive IoT (mIoT) scenarios, characterized by a huge deployment of energy-constrained IoT devices, we propose an efficient Next Generation Multiple Access (NGMA) scheme where several innovative solutions combine and integrate. First, we aim to maximize the spectral efficiency of the Physical Uplink Shared Channel (PUSCH) by adopting the most appropriate Non-Orthogonal Multiple Access (NOMA) technique and by introducing an efficient contention-based approach for data transmission in the unused PUSCH resources. Second, on basis of the traffic load, the proposed scheme dynamically sets the UpLink (UL) radio resources dimensioning by searching the optimal trade-off between lowering the collision probability in the Physical Random Access Channel (PRACH) and providing enough radio resources in the PUSCH to permit the data transmission to all the succeeded access requests. Third, it is enriched by a series of strategic procedures to make feasible the traffic load estimation, even when the PRACH is in overload condition. Fourth, we exploit Artificial Intelligence technologies to further optimize the performances obtained. The proposed scheme is compared with other benchmark schemes available in the literature. It outperforms them in the most important metrics for the mIoT scenario (i.e., spectral efficiency and energy consumption), especially in high load conditions, which is the expected requirement for Beyond 5G and 6G networks.

Evaluating the Effect of Binder for Sulfurized Polyacrylonitrile Cathode via Optical Fiber Sensors

AbstractSulfurized polyacrylonitrile (SPAN) is a very stable and promising sulfur‐based cathode material for high energy density lithium–sulfur (Li–S) batteries, which can circumvent the polysulfides dissolution issue. However, the stress concentration caused by volume change in SPAN cathodes is relatively significant but is rarely focused on. It is widely reckoned that the binder plays a key role in buffering the stress induced by electrode materials and hence maintains the integrity of electrodes. Nevertheless, the understanding of the actual effect of binders to SPAN cathodes from the aspect of mechanics remains to be deepened. Here, the optical fiber Bragg grating (FBG) is implanted into SPAN cathode films to in situ evaluate the electrochemo‐mechanical behaviors by using four different binders. The internal strain evolution of SPAN cathodes is affected by multiple factors of adhesion and mechanical properties of different binders. It is found that the SPAN cathode using poly(acrylic acid) (PAA) binder with outstanding mechanical properties experiences the largest strain change but the electrochemical performance is even better under high sulfur loading. Furthermore, the strain evolution is monitored under high sulfur loading condition and how the sulfur loading affects the signals of the built‐in FBG sensors is tried to figure out.

Intermetallic compound and martensitic transformation in Ag/Cu co-modified Ti6Al4V alloy

Titanium and its alloys are promising materials for engine production, special pump manufacturing, and bone implants. However, the abrasion resistance and fracture toughness of Ti alloys are insufficient to withstand extreme high loading conditions and harsh environments. Surface modification is an effective way to improve the performance of Ti alloys. In this study, Ag and Cu were added to Ti6Al4V alloy through friction stir processing to modify its surface. The different ratios of the Ag/Cu powder mixture were designed to optimize the surface modification of Ti6Al4V, and the relationship between intermetallic compounds and martensitic transformation was analyzed. The martensitic transformation was induced by AgCuTi phases. The submicron-size martensite was distributed outside the AgCuTi particle, while the nano-laminar martensitic band was generated inside the AgCuTi particle. Under the co-modification of Ti alloy using Ag and Cu, the surface of Ti6Al4V alloy exhibited higher hardness (4.3 GPa) values and lower modulus (100.6 GPa), which gave the credit to the formation of AgCuTi and martensitic transformation. The alloy specimen was subjected to short heat treatment at 600 °C for 30 min to further modify the gradient structure. After the short heat treatment of the Ag/Cu co-modified specimen, a lower modulus (88.8 GPa) and a high level of hardness (4.1 GPa) were achieved. In addition, superelastic strain recovery was also enhanced, showing the further induced martensitic transformation. This work provides new insight into the surface modification of titanium alloys using the FSP method to achieve the ideal hardness and elastic modulus balance.

Fiber-Type-Specific Hypertrophy with the Use of Low-Load Blood Flow Restriction Resistance Training: A Systematic Review.

Emerging evidence indicates that the use of low-load resistance training in combination with blood flow restriction (LL-BFR) can be an effective method to elicit increases in muscle size, with most research showing similar whole muscle development of the extremities compared to high-load (HL) training. It is conceivable that properties unique to LL-BFR such as greater ischemia, reperfusion, and metabolite accumulation may enhance the stress on type I fibers during training compared to the use of LLs without occlusion. Accordingly, the purpose of this paper was to systematically review the relevant literature on the fiber-type-specific response to LL-BFR and provide insights into future directions for research. A total of 11 studies met inclusion criteria. Results of the review suggest that the magnitude of type I fiber hypertrophy is at least as great, and sometimes greater, than type II hypertrophy when performing LL-BFR. This finding is in contrast to HL training, where the magnitude of type II fiber hypertrophy tends to be substantially greater than that of type I myofibers. However, limited data directly compare training with LL-BFR to nonoccluded LL or HL conditions, thus precluding the ability to draw strong inferences as to whether the absolute magnitude of type I hypertrophy is indeed greater in LL-BFR vs. traditional HL training. Moreover, it remains unclear as to whether combining LL-BFR with traditional HL training may enhance whole muscle hypertrophy via greater increases in type I myofiber cross-sectional area.

Numerical Analysis of Propeller Wake Evolution under Different Advance Coefficients

Propeller wake fields in an open-water configuration were compared between two loading circumstances using large-eddy simulation (LES) with a computational domain of 48 million grids and an overset mesh technique. To validate the results of the numerical simulation, available experimental data are compared, which indicates that the grid systems are suitable for the present study. The results indicate that the present LES simulations describe the inertial frequency range well for both high and low-loading conditions. Under high-loading conditions, the interlaced spirals and secondary vortices that connect adjacent tip vortices amplify the effects of mutual inductance, ultimately triggering the breakdown of the propeller wake systems. At a great distance from the propeller, the vortex system loses all coherence and turns into a collection of smaller vortices that are equally scattered across the wake. In contrast, under light-loading conditions, the wake vortex system exhibits strong coherence and has a relatively simple topology. The elliptic instability and pairing processes are only observed at a far distance from the propeller. The convection velocity transferring tip vortices downstream is larger under the light-loading condition, which leads to the larger pitch of the helicoidal vortices. The larger pitch weakens the mutual inductance or interaction effects among tip vortices, which delays the instability behaviors of the whole vortex system. The results and implications of this study serve as a guide for the development and improvement of next-generation propellers that function optimally when operating behind aquaculture vessels.

Experimental Study on Combustion Characteristics and Regulated and Unregulated Emissions of a Common-Rail Diesel Engine Fueled with Waste Cooking Oil Biodiesel

<div>The demand for fossil fuels can be reduced and environmental harm can be minimized by producing biodiesel from used cooking oil. This article was focused on investigating the combustion characteristics and regulated and unregulated emissions of a common-rail diesel engine fueled with different mixed concentrations of biodiesel and diesel fuel, including pure diesel fuel (B0), B10 (diesel containing 10%vol of biodiesel), B20, and B30. Experiments were conducted with three engine loads, corresponding to brake mean effective pressures (BMEP) of 0.289 MPa, 0.578 MPa, and 0.867 MPa at a constant speed of 1540 rpm. At medium and high loads, the waste cooking oil biodiesel (WCOB) increased in-cylinder pressure, advanced both the peak heat release rate and heat release center (CA50), shrunk the ignition delay (ID), and extended combustion duration (CD). The high viscosity of B30 blends under low load worsened the spray and led to poor combustion. Under high-load conditions, carbon dioxide (CO<sub>2</sub>) and nitrogen oxides (NO<sub>x</sub>) emissions increased by 14.3% and 3.1%, while carbon monoxide (CO), soot, and total hydrocarbon (THC) emissions decreased by 13.3%, 31.4%, and 30.37%, respectively, for the B30 blend compared to diesel. The emission trends for nitrogen dioxide (NO<sub>2</sub>), formaldehyde (HCHO), methane (CH<sub>4</sub>), ammonia (NH<sub>3</sub>), ethylene (C<sub>2</sub>H<sub>4</sub>)<sub>,</sub> and formic acid (HCOOH) were consistent with increasing volume ratios of WCOB under the three loads. And they had the lowest emissions at 75% load for B30, with reductions of 70.5%, 66.7%, 18.4%, 78.8%, 13.2%, and 84.6%, respectively, compared to diesel. Acetaldehyde (MECHO) emissions increased with increasing WCOB blending volume ratio at 25% load condition and were highest at the B30 blend. The above results show that the B30 blend is the most effective in reducing unregulated emissions under all three load conditions, especially at medium and high loads.</div>

고각구동 프레임 구조물의 힌지 위치에 따른 최적설계 및 해석

In this paper, the design of a high-angle drive frame structure supporting a large load while considering the necessary variables such as hinge position and frame weight is presented; furthermore, the geometrical design variables are solved through geometric boundary conditions and optimal deflection equations. This study consists of two parts. First, the mathematical model of the deflection under the high load condition of the high-angle drive frame, boundary conditions, and design variables are selected, and the solution of the geometric deflection equation are then checked. The cross-section of the frame has a rectangular shape, and the deflection model is a two-point support simple beam model. The deflection equation and boundary condition equation of the high-angle drive frame are determined using the hinge position and frame length. Second, the validity of the deflection equation is verified through finite element analysis; further, it is verified whether the hinge position and frame length corresponding to the geometric solution satisfy the optimal deflection. The optimal geometrical design parameters for designing a high-angle driving frame structure that can withstand high loads are determined. Then the appropriateness of the optimal solution is demonstrated through structural analysis. Finally, the validity of the geometrical optimization method is verified.

Off-Cycle Emissions of Particle Number from Gasoline and DPF Diesel Passenger Cars in High-Load Conditions

To evaluate regulated gases and solid particle number (SPN) emissions in high-load off-cycle conditions, two diesel vehicles with a diesel particulate filter (DPF) and a urea selective catalytic reduction (SCR) system, respectively, and four gasoline port fuel injection (PFI) vehicles were tested with the worldwide light-duty test cycle, including an extra-high (Ex-hi) phase. All the tested vehicles were developed for the Japanese market and did not comply with the Ex-hi phase. All vehicles exhibited higher CO2 emissions in the Ex-hi phase than in low, the mid and high phases. Increased NOx and SPN10-23 emissions were observed with the DPF vehicle. These increased emissions were due to the occurrence of passive regeneration of the DPF, and the urea SCR system was stopped as a result. The small gasoline PFI cars showed increased CO and SPN emissions in the Ex-hi phase. These emissions were due to enrichment control, which occurred in a quite high load operation condition. The feature of higher emissions with enrichment control differed from that observed in a warming-up process in the cold-start mode. SPN23 increased mainly in the warming-up process, whereas SPN10-23 increased in the Ex-hi phase with enrichment control. Hybrid vehicles seem to have fewer opportunities to show the enrichment control due to motor assist.

A methodology for performance prediction: Hydrodynamic investigation of spiral grooved thrust bearing

AbstractThis paper presents the design and numerical optimization of oil‐lubricated spiral grooved thrust bearing (SGTB) for its application at high speed and axial loading conditions. A numerical model is developed using nonlinear incompressible Reynold's equation and is solved using the finite volume method (FVM) to determine the static characteristics over the bearing surface. Further, the influence of groove parameters such as spiral angle, groove angle, film thickness ratio, number of grooves and speed on the static characteristics of the bearing has been investigated. The result shows that the designed oil‐lubricated SGTB can operate at high‐speed conditions and withstand high axial load. Further, the characteristic data sets acquired from the numerical analysis are trained using an artificial neural network (ANN), and their performance is evaluated through the computation of the regression coefficient. Then adaptive neuro‐fuzzy interface system (ANFIS) surface plot is obtained to determine the optimum bearing parameters.

Extraction of Nitric Acid and Uranium with DEHiBA under High Loading Conditions.

The mechanism by which high concentrations (1.5 M in n-dodecane) of N,N-di-2-ethylhexyl-isobutyramide (DEHiBA) extracts HNO3 and UO2(NO3)2 is under examination. Most prior studies have examined the extractant and the mechanism at a concentration of 1.0 M in n-dodecane; however, under the higher loading conditions that can be achieved by a higher concentration of extractant, this mechanism could change. Increased extraction of both nitric acid and uranium is observed with an increased concentration of DEHiBA. The mechanisms are examined by thermodynamic modeling of distribution ratios, 15N nuclear magnetic resonance (NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy coupled with principal component analysis (PCA). Speciation diagrams produced through thermodynamic modeling have been qualitatively reproduced through PCA of the FTIR spectra. The predominant extracted species of HNO3(DEHiBA), HNO3(DEHiBA)2, and UO2(NO3)2(DEHiBA)2 are in good agreement with prior literature reports for 1.0 M DEHiBA systems. Evidence for an additional species of either UO2(NO3)2(DEHiBA) or UO2(NO3)2(DEHiBA)2(HNO3) also contributing to the extraction of uranium species is given.

Increased muscle force does not induce greater stretch-induced damage to calf muscles during work-matched heel drop exercise

PurposeTo investigate the effect of muscle force during active stretch on quantitative and qualitative indicators of exercise-induced muscle damage (EIMD) in the medial gastrocnemius (MG) muscle.MethodsTwelve recreationally active volunteers performed two trials of an eccentric heel drop exercise. Participants performed a single bout of low-load (body weight) and high-load (body weight + 30% body weight) exercises on separate legs. The total mechanical work output for each condition was matched between legs. Before, two hours and 48 h after each bout of eccentric exercise, electrically stimulated triceps surae twitch torque, muscle soreness, MG active fascicle length at maximum twitch torque and muscle passive stiffness were collected. Triceps surae electromyographic (EMG) activity, MG fascicle stretch and MG muscle–tendon unit (MTU) length were measured during the eccentric tasks.ResultsThe high-load condition increased triceps surae muscle activity by 6–9%, but reduced MG fascicle stretch (p < 0.001). MTU stretch was similar between conditions. The greater muscle force during stretch did not give rise to additional torque loss (5 vs 6%) or intensify muscle soreness.ConclusionsAdding 30% body weight during eccentric contractions has a modest impact on exercise-induced muscle damage in the medial gastrocnemius muscle. These results suggest that muscle load may not be an important determinant of stretch-induced muscle damage in the human MG muscle. The muscle investigated does exhibit large pennation angles and high series elastic compliance; architectural features that likely buffer muscle fibres against stretch and damage.

Enhancing anammox nitrogen removal by static magnetic field exposure: Performance, microbial community and symbiotic relationship analysis

Anammox batch reactors were operated with different static magnetic field (SMF) intensities (0 mT, 40 mT, and 100 mT). The impacts of SMF and the influent nitrogen concentration on nitrogen removal were analyzed. Sludge characteristics, microbial community structure, and metabolism pathways were explored. The results show that a high nitrogen load greatly decreased the nitrogen removal efficiency. Still, applying SMF with appropriate intensity enhanced the nitrogen removal performance, especially under high nitrogen loading conditions. Systems with 40 mT SMF at normal nitrogen loading conditions had the highest total nitrogen removal efficiency. In contrast, a higher SMF intensity was conducive to the anammox process with a high nitrogen load. Candidatus Kuenenia was fast enriched under high nitrogen loading conditions in the control systems. However, Candidatus Brocadia was more abundant than Ca. Kuenenia in the systems with SMF application. SMF was the main factor affecting the microbial metabolism, enhancing the metabolic pathways related to bacterial growth and resistance to environmental stress. The metabolic interactions between the anammox bacteria and other bacteria were enhanced by applying SMF to the anammox process, especially for the cross-feeding of cofactors and vitamins in the anammox consortia.