Force Levels Research Articles

VOF study of mesoscale bubble flow dynamics in the side-blown gas–liquid two-phase reactor

Understanding the flow and mixing characteristics of mesoscale bubbles within side-blown gas–liquid two-phase systems is paramount for the design and optimization of associated industrial processes. This study elucidates the gas–liquid side-blown two-phase reactor, employing the volume of fluid method coupled with the realizable k-ε turbulence model. Following the model validation through experimental measurements, the mesoscale bubble dynamics, flow characteristics, and multiscale coupling mechanisms inherent to side-blown gas–liquid reactor are explored. The key insights can be obtained: (1) the upward trajectory of bubbles originating from side-injection gas can be categorically divided into four phases with different bubble behaviors. (2) A reduction in the ratio of inertial forces to buoyancy forces during bubble ascent induces a decrease in the bubble shape factor. This transition manifests as a shift from vertical to flattened bubble shapes within the transition and plume regions. (3) Bubbles undergo transitions between states characterized by high buoyancy and low surface tension, accompanied by varying levels of viscous forces during their ascent. These dynamic states render bubbles susceptible to breakup. Under conditions of a constant nozzle diameter, the maximum bubble size within the reactor is inherently restricted. (4) Drawing upon the correlation between bubble Weber and Reynolds numbers, a predictive formula for determining the characteristic velocity of bubbles within side-blown reactors is proposed:uc=σ1-0.456(ρlLC)0.456512μl11.36Overall, this work offers meaningful insights into the fundamental mechanisms governing bubble cluster dynamics within side-blown gas–liquid reactors.

Prevalence of degenerative vertebral disc changes in elite female Crossfit athletes – a cross-sectional study

BackgroundCrossfit athletes consistently recruit or transfer high levels of repetitive forces through the spine, and MRI has documented a higher rate of intervertebral disc degeneration in athletes compared with matched controls. The aim of this study was to evaluate early degenerative spinal disc changes in elite female CrossFit athletes quantified by 3.0 Tesla magnetic resonance imaging (MRI) matched with female none-athletes.MethodsIn a cross-sectional single-center study 19 asymptomatic adult participants, nine German female elite Crossfit athletes and ten female participants underwent spinal MRI (3.0T). Demographic data, spinal clinical examination results and sport-specific performance parameters were collected prior to the MRI. The primary outcome was the prevalence of degenerative spinal disc changes. The secondary outcome was the grade of degeneration using Pfirrmann grading.ResultsA total of 437 discs underwent spinal MRI (3.0T). The prevalence of early degenerative disc disease was not increased. Pfirrmann degenerative grade did not show significant differences among groups.ConclusionAsymptomatic female elite Crossfit athletes do not show an increased prevalence of degenerative disc disease. Compared to a sex-matched control group, high training volume in Crossfit does not correlate to a higher incidence of degenerative disc changes in young females.

Biomechanics and finite element analysis comparing posterior T-plates with LCP for fixation of posterolateral tibial plate fractures.

Objective: The treatment for posterolateral tibial plateau fractures (PTPF) have been subjects of controversy. We conducted a study to improve the fixation of PTPF through a lateral approach. Methods: We utilized 40 synthetic tibias and categorized the fracture models into five groups based on the locking compression plate (LCP) and T-distal radius plate (TPP) via various forms of fixation with screws through the posterolateral (PL) fracture fragments. I: Two-screw fixation using two locking screws (LPTL). Ⅱ: Two-screw fixation with both variable angle locking screws (LPTV). Ⅲ: One-screw fixation with one locking screw (LPOL). Ⅳ: One-screw fixation with one locking screw and two anteroposterior lag screws (LPOLTL). Ⅴ: a distal radius plate with three locking screws (TPP). Biomechanical tests were conducted to observe the axial compression displacement of the PL fracture fragments at force levels of 250N, 500N, and 750N, as well as to determine the failure load and the axial stiffness for each respective group. Results: Under a 750N load condition, the displacements within the five experimental groups exhibited the following trend: Ⅴ < Ⅱ < Ⅰ< Ⅳ < Ⅲ. However, there were no significant differences between Group V and Group II, Group I and Group IV (p > 0.05), and only Group Ⅲ demonstrated a displacement exceeding 3mm. The failure load and the axial stiffness exhibited the same trend. Conversely, statistical significance was identified among the remaining group compared with Group Ⅲ (p < 0.05). Regarding the finite element analysis, the maximum displacements for the five models under the load of 750N exhibited the following trend: Ⅴ < Ⅱ < Ⅰ< Ⅳ < Ⅲ. The following trends were observed in maximum von Mises stresses for these models under the load of 750N: Ⅴ < Ⅱ < Ⅳ< Ⅰ < Ⅲ. Conclusion: It is crucial to address the inadequate mechanical strength associated with single screw fixation of LCP for fixing PL fractures in a clinical setting. The biomechanical strength of two-screw fixation surpasses that of single-screw fixation. Introducing variable-angle screws can further enhance the fixation range. Furthermore, the addition of two lag screws threaded from anterior to posterior can compensate the mechanical stability, when PL fracture is fixed with single screw in clinic.

Strain inhibition of bacterial collagenase is consistent with a collagen fibril uncrimping mechanism in rat tail tendons

Mechanical strain inhibits bacterial collagenase from cleaving collagen. Additionally, the toe region of a soft tissue’s force–elongation curve arises from sequentially engaging collagen fibrils as the tissue lengthens. Together, these phenomena suggest that mechanical strain may gradually inhibit collagenase activity through a soft tissue’s toe region. Therefore, this investigation sought to test this hypothesis.92 rat tail tendon fascicles from 3 female sentinel animals underwent preliminary stiffness tests, and their force–elongation curves were fit to a collagen distribution model. This distribution-based model calculated the force magnitude corresponding to p% of collagen fibril engagement. Specimens were separated into one of five levels of p, and that level of force was maintained for two hours while being exposed to 0.054 U/mL of bacterial collagenase from C. histolyticum. The specimens were strained to failure following the creep test, and the relative reduction in stiffness was quantified to estimate the fraction of digested fibrils.Every 10% additional collagen engagement corresponded to a 6.3% (97% highest density interval: 4.3 – 8.4%) retention of stiffness, which indicated collagenase inhibition.The results of this investigation were consistent with a strain-inhibition hypothesis along with the established uncrimping mechanism in the toe region. These results support an interaction between mechanical strain and collagenolysis, which may be valuable for disease prevention or treatment.

Influence of Mental Training of Attentional Control on Autonomic Arousal Within the Framework of the Temporal Preparation of a Force Task.

While temporal preparation has frequently been examined through the manipulation of foreperiods, the role of force level during temporal preparation remains underexplored. In our study, we propose to manipulate mental training of attentional control in order to shed light on the role of the force level and autonomic nervous system in the temporal preparation of an action. Forty subjects, divided into mental training group (n = 20) and without mental training group (n = 20), participated in this study. The influence of the attentional control and force levels on the autonomic nervous system were measured using the skin conductance response and the heart rate variability; the accuracy of the motor responses was measured using a method derived from machine learning. Behaviorally, only the mental training group reinforced its motor and attentional control. When using short foreperiod durations and high force level, motor and attentional control decreased, consistent with the dominant sympathetic system. This resulted in an increased anticipation rate of responses with a higher reaction time compared to the long foreperiods duration and low force level, in which the reaction time significantly decreased, with enhancement of the expected force level, showing consistency with the dominant parasympathetic system. Interestingly, results revealed a predictive relationship between the sympathovagal balance and motor and attentional control during the long foreperiods and low force level. Finally, results demonstrate that attentional mental training leads to the reinforcement of interactions between the autonomic nervous system and attentional processes which are involved in the temporal preparation of a force task.

Prediction of large deflection of chromium nanobeams using a hybrid meta-heuristic algorithm

In this paper, the prediction of large deflection of the chromium nanobeams has been studied using hybrid meta-heuristic methods. At first, using the full factorial design of experiment method, 100 experiments were designed in which the length and force applied to the nanobeams were considered as input variables at 25 and 4 levels, respectively. Also, the deflection of the nanobeam was considered as the output. The nanobeam’s deflection was estimated through the regression models by first, second, and third-order equations, respectively. The preliminary results demonstrated that the third-order regression model predicts the deflection with high accuracy and its error is less than the other models. In the following, to reduce the number of required experiments, two levels of the applied force (8 and 11 nN) were used to predict the deflection. Accordingly, the new equations were used for interpolation and extrapolation of the deflection in other levels of forces i.e., 9.5 and 12.5 nN. Finally, the coefficients of both third-order equations obtained by 4 and 2 levels of forces were optimized using the meta-heuristic algorithms i.e., Big Bang-Big Crunch (BBBC) and Ray Optimization algorithm (ROA). Comparing the results showed that by using the BBBC and RAO methods, the error value decreases by 10% and 20%, respectively. The results of this paper showed that the deflections of the chromium nanobeam can be estimated by algebraic formulas with high accuracy and fewer experiments, time, and cost.

PropelWalker: A Leg-Based Wearable System With Propeller-Based Force Feedback for Walking in Fluids in VR.

There has been an increasing focus on haptic interfaces for virtual reality (VR), to support a high-quality touch experience. However, it is still challenging to haptically simulate the real-world walking experience in different fluid mediums. To tackle this problem, we present PropelWalker, a pair of calf-worn haptic devices for simulating the buoyancy and the resistant force when the human's lower limbs are interacting with different fluids and materials in VR. By using four ducted fans, two installed on each calf, the system can control the strength and the direction of the airflow in real time to provide different levels of force. Our technical evaluation shows that PropelWalker can generate vertical forces up to 27N in two directions (i.e., upward and downward) within 0.85 seconds. Furthermore, the system can stably maintain the generated force with minor turbulence. We further conducted three user-perception studies to understand the capability of PropelWalker to generate distinguishable force stimuli. First, we conducted the just-noticeable-difference (JND) experiments to investigate the threshold of the human perception of on-leg air-flow force feedback. Our second perception study showed that users could distinguish four PropelWalker-generated force levels for simulating different walking mediums (i.e., dry ground, water, mud, and sand), with an average accuracy of 94.2%. Lastly, our VR user study showed that PropelWalker could significantly improve the users' sense of presence in VR.

Experimental Investigation of High-Force-To-Volume Extrusion Damper Subjected to Cyclic and Time History Loading

Abstract The ability of energy dissipation from earthquake force in a controlled and iterative manner will play a vital role in maintaining structural reliability for various forces. High force-to-volume (HF2V) extrusion damper is a promising technology with simple designs, high damping force and achieving design requirements. This paper develops HF2V extrusion damper with multiple toothing configuration for seismic application. The experimental verification has been undertaken on lead extrusion dampers with various frequency range of 0.5 to 2 Hz. The maximum load-carrying capacity is 10.48 kN with strokes up to 5mm are observed with hysteresis loop with some recentering capability has a stiffness value up to 2*106 N/m, and force levels up to 2-10 kN. The maximum load carrying capacity for time history loading for Northridge earthquake is 11.57 kN. The overall findings suggest that silicone sealant may be employed to build and characterize extrusion dampers with maximum energy dissipation and high force/volume interactions. The suggested device may be a potentially effective way to provide additional energy dissipation to structures in seismic zones, according to the mechanical characteristics to the frequency. Additionally, the system can withstand for earthquake time histories, and ensuring maintenance-free operation even in the midst of frequent ground vibration.

Mechanobiological cell adaptations to changing microenvironments determine cancer invasiveness: Experimentally validated finite element modeling.

Metastases are the leading cause of cancer-associated deaths. A key process in metastasis is cell invasiveness, which is driven and controlled by cancer cell interactions with their microenvironment. We have previously shown that invasive cancer cells forcefully push into and indent physiological stiffness gels to cell-scale depths, where the percentage of indenting cells and their attained depths provide clinically relevant predictions of tumor invasiveness and the potential metastatic risk. The cell-attained, invasive indentation depths are directly affected by gel-microenvironment mechanics, which can concurrently modulate the cells' mechanics and force application capacity, in a complex, coordinated mechanobiological response. As it is impossible to experimentally isolate the different contributions of cell and gel mechanics to cancer cell invasiveness, we perform finite element modeling with literature-based parameters. Under average-scale, cell cytoplasm and nucleus mechanics and cell-applied force levels, increasing gel stiffness 1-50 kPa significantly reduced the attained indentation depth by >200%, while the gel's Poisson ratio reduced depths only by up to 20% and only when the ratio was >0.4; this reveals microenvironment mechanics that can promote invasiveness. Experiments with varying-invasiveness cancer cells exhibited qualitative variations in their responses to gel stiffness increase, for example large/small reduction in indentation depth or increase and then reduction. We quantitatively and qualitatively reproduced the different experimental responses via coordinated changes in cell mechanics and applied force levels. Thus, the different cancer cell capacities to adapt their mechanobiology in response to mechanically changing microenvironments likely determine the varying cancer invasiveness and metastatic risk levels in patients.

On frequency‐domain estimation of increase in design yield force levels of SDOF structures due to multiplicity of earthquake events

AbstractThe current earthquake design philosophy based on only the most critical earthquake may prove inadequate when the smaller events occurring before this event cause significant damage to the structure and repairs become infeasible. The design force levels may therefore be raised using the modified design force ratio, defined as the ratio of the yield force level for a specified damage level under all the seismic events to the yield force level for the same damage level under only the most critical event. This study considers the updating of the existing frequency‐based approach, using the power spectral density function (PSDF)‐based characterization of design ground motion, for the estimation of modified design force ratio spectrum. First, an empirical expression developed in the companion paper for modifying the damping of the equivalent linear oscillator is used such that the use of the PSDF compatible with 5%‐damping response spectrum leads to correct peak response, even when the equivalent damping ratio exceeds 5%. Next, the frequency‐domain design force ratio estimates are benchmarked in the case of steel and reinforced concrete oscillators by comparing those with the time‐domain estimates of equivalent Bouc–Wen oscillators over various sequences of events and by suitably adjusting the stiffness degradation parameter. It is shown in the case of a hypothetical seismic scenario that the optimal values of this parameter as 2.0 and 1.7 work well for the steel structures and reinforced concrete structures with high stiffness degradation respectively. Also, the proposed approach needs to be improved further for applicability in the case of reinforced concrete structures exhibiting significant pinching behavior.

Cyclic Behavior of a Novel MADAS Damper with No Axial Force and Improved Seismic Performance (Experimental, Numerical, and Analytical Assessment)

ABSTRACT Axial forces are generated in the plates of ADAS-yielding dampers when subjected to lateral loading due to their boundary conditions. This on one hand can lead to an increase in strain level of the plates and accelerate the damage process, while on the other hand, the interaction of the bending moment with the tensile axial force leads to increasing strength, which is undesirable in the performance of ductile members. In this paper, a modified ADAS device (MADAS) is introduced to prevent undesirable interaction of axial forces, and its cyclic behavior is evaluated both experimentally and numerically. To this end, in the first step, two test specimens with different number of connection pins were prepared and subjected to cyclic loading in a rigid frame. Experimental and numerical results have shown that due to the removal of the constraint in the vertical direction, the level of forces produced by the damper is almost constant and the X-shaped plates have been able to tolerate significant number of cycles before crack initiation. Afterwards, the cyclic performance of ADAS and MADAS dampers was numerically compared individually and also when placed in the frame. Furthermore, in the frame equipped with ADAS damper, the increase in the level of forces produced by the damper led to the buckling of the braces, while the level of generated forces was totally in the expected range in the frame equipped with MADAS damper.

The Influence of Online and Offline Sales at Marina Bakoel Klambi Shop

The current level of intense business competition forces businesspeople to continue trying to maintain their operations and compete to achieve predetermined goals. Now, selling products involves more than just offline sales or so-called traditional sales, but also utilizing information technology. Toko Marina Bakoel Klambi is faced with the problem of sales methods. Whether to stay focused on traditional methods or use information technology in the present, this study uses quantitative methods using multiple linear regression analysis in software in the form of SPSS 25 tools. Based on the results of the analysis at the 0.05 significance level, it shows that sales so far have a significant effect on the level of sales. Conversely, it can be proven that offline sales do not influence the level of sales. In addition, in the simultaneous significance test offline and during sales have a significant impact on the number of sales. So, in this case, the comparison of sales at Toko Marina Bakoel Klambi in terms of time is more useful for sellers in boosting sales

Threshold in breast compression reduction for full-field digital mammography and digital breast tomosynthesis

IntroductionBreast compression is essential in mammography to improve image quality and reduce radiation dose. However, it can cause discomfort or even pain in women which could discourage them from attending future mammography examinations. Therefore, this study aims to explore the maximum reduction in breast compression in full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT) that is achievable without impacting on image quality and dose. MethodsTen compression force (CF) levels (20N–110N, with 10N intervals) were assessed on Siemens MAMMOMAT Inspiration with Nuclear Associates 18–228 phantom. Imaging was carried out in craniocaudal projection using Automatic Exposure Control at 28 kVp with a Tungsten/Rhodium anode/filter combination, and at 50° sweep angle for DBT. Using ImageJ software, image quality of the acquired mammograms and central tomosynthesis slices were examined based on mass conspicuity (MC) and microcalcification conspicuity (MicroC). Entrance skin dose (ESD) and mean glandular dose (MGD) were recorded from Digital Imaging and Communication in Medicine image header. Linear regression was performed to examine the relationship between CF with ESD, MGD, MC and MicroC. Differences in image quality and radiation dose were assessed with one-way analysis of variance and Kruskal-Wallis H test. ResultsSignificant correlations were noted between CF with ESD and MicroC for FFDM and DBT, with DBT also demonstrating associations with MGD and MC. No significant differences were observed for ESD, MGD, MC and MicroC when CF was reduced to 40N and 80N in FFDM and DBT respectively. ConclusionThis study demonstrated that CF can be reduced as low as 40N and 80N in FFDM and DBT respectively, without significant impact on image quality and radiation dose. Implications for practiceReduced mammographic compression may reduce discomfort or pain in women, which may improve attendance rate in breast screening programmes. Findings from this study will provide reference for future work examining breast compression in mammography.

Crashworthiness of Foam-Filled and Reinforced Honeycomb Crash Absorbers in Transverse Direction

AbstractHoneycomb crash absorbers have been widely studied as energy absorption devices for use in automotive industries. However, none of these investigations have studied the side impact of empty and foam-filled honeycomb absorbers and adding stiffeners between the different layers of the corrugated sheets which are composing the honeycomb structure to analyse the structure under transverse (L-direction) impacts. In this paper, the foam-filled and reinforced honeycomb crash absorbers are investigated under axial (T) and transverse (L) loading directions. Experimental results for both empty and foam-filled specimens under quasi-static and impact loads were implemented to validate the developed finite element model. Finite element analysis (FEA) was performed to find out the crashworthiness behaviour of the structure under axial and transverse impacts according to road conditions. Finally, a new design of stiffened honeycomb crash absorber was developed and investigated to reduce the level of acceleration experienced by the passengers during the crash event. In this regard, it is concluded that all the requirements related to the energy absorption capabilities and generated deceleration under impact loading can be met by introducing an advanced method to reinforce honeycomb absorbers using stiffeners. It is also proven that the thickness of these stiffeners will not significantly influence the force levels. Due to increase of wall thickness from 1 to 3 mm, the mean crushing force increased from 129 kN to 148 kN. This growth is not sufficient as the goal is to obtain a mean crushing force of 300 kN. Thickening the stiffeners would lead to a loss of efficiency of the structure, as the small increase in mean force would not make up for the gain in mass. Thus, increasing the corrugated sheet’ thickness becomes necessary.

Effect of clinical experience and training with visual feedback on standardized palpation outcomes-Potential implications for assessment of jaw muscle sensitivity.

The evaluation of muscle pain and sensitivity by manual palpation is an important part of the clinical examination in patients with myalgia. However, the effects of clinical experience and visual feedback on palpation of the masticatory muscles with or without a palpometer are not known. To estimate the effects of clinical experience and visual feedback on the accuracy of palpation in standardized settings. Thirty-two dentists (age 35 ± 11 years) classified as either specialists (n = 16) or generalists (n = 16) participated in this experiment. All dentists were instructed to target force levels of 500- or 1000-gf, as determined on an electronic scale using either standardized palpometers or manual palpation (MP). All dentists participated in four different tests: MP, MP with visual feedback (MPVF), palpometer (PAL) and PAL with visual feedback (PALVF). Actual force values for each type of palpation from 0 to 2, 2 to 5 and 0 to 5 s were analysed by calculating target force level. The relative differences during 2-5 and 0-5 s with 1000 gf were significantly lower for generalists than for specialists (p < .05). In generalists and specialists, the coefficients of variation and the relative differences during 2-5 s were significantly lower for PAL and PALVF than for MP (p < .05). These findings suggest that the use of a palpometer, but not clinical experience with palpation of masticatory muscles, increases the accuracy of palpation, and ≥2 s of palpation with a palpometer is optimal for masticatory muscles.

Force-Triggered Self-Destructive Hydrogels.

Self-destructive polymers (SDPs) are defined as a class of smart polymers that autonomously degrade upon experiencing an external trigger, such as a chemical cue or optical excitation. Because SDPs release the materials trapped inside the network upon degradation, they have potential applications in drug delivery and analytical sensing. However, no known SDPs that respond to external mechanical forces have been reported, as it is fundamentally challenging to create mechano-sensitivity in general and especially so for force levels below those required for classical force-induced bond scission. To address this challenge, the development of force-triggered SDPs composed of DNA crosslinked hydrogels doped with nucleases is described here. Externally applied piconewton forces selectively expose enzymatic cleavage sites within the DNA crosslinks, resulting in rapid polymer self-degradation. The synthesis and the chemical and mechanical characterization of DNA crosslinked hydrogels, as well as the kinetics of force-triggered hydrolysis, are described. As a proof-of-concept, force-triggered and time-dependent rheological changes in the polymer as well as encapsulated nanoparticle release are demonstrated. Finally, that the kinetics of self-destruction are shown to be tuned as a function of nuclease concentration, incubation time, and thermodynamic stability of DNA crosslinkers.

3D muscle networks based on vibrational mechanomyography

Objective. Muscle network modeling maps synergistic control during complex motor tasks. Intermuscular coherence (IMC) is key to isolate synchronization underlying coupling in such neuromuscular control. Model inputs, however, rely on electromyography, which can limit the depth of muscle and spatial information acquisition across muscle fibers. Approach. We introduce three-dimensional (3D) muscle networks based on vibrational mechanomyography (vMMG) and IMC analysis to evaluate the functional co-modulation of muscles across frequency bands in concert with the longitudinal, lateral, and transverse directions of muscle fibers. vMMG is collected from twenty subjects using a bespoke armband of accelerometers while participants perform four hand gestures. IMC from four superficial muscles (flexor carpi radialis, brachioradialis, extensor digitorum communis, and flexor carpi ulnaris) is decomposed using matrix factorization into three frequency bands. We further evaluate the practical utility of the proposed technique by analyzing the network responses to various sensor-skin contact force levels, studying changes in quality, and discriminative power of vMMG. Main results. Results show distinct topological differences, with coherent coupling as high as 57% between specific muscle pairs, depending on the frequency band, gesture, and direction. No statistical decrease in signal strength was observed with higher contact force. Significance. Results support the usability vMMG as a tool for muscle connectivity analyses and demonstrate the use of IMC as a new feature space for hand gesture classification. Comparison of spectrotemporal and muscle network properties between levels of force support the robustness of vMMG-based network models to variations in tissue compression. We argue 3D models of vMMG-based muscle networks provide a new foundation for studying synergistic muscle activation, particularly in out-of-clinic scenarios where electrical recording is impractical.

Accuracy of Force Generation and Preparatory Prefrontal Oxygenation in Ballistic Hand Power and Precision Grips

It remains unclear whether accurate motor performance and cortical activation differ among grasping forms across several force levels. In the present study, a ballistic target force matching task (20%, 40%, 60%, and 80% of maximum voluntary force) with power grip, side pinch, and pulp pinch was utilized to explore the accuracy of the forces generated as well as the muscular activity of intrinsic and extrinsic hand muscles. By using near-infrared spectroscopy, we also examined bilateral dorsolateral prefrontal cortex (DLPFC) activation during the preparatory phase (initial 10 s) of the task. The accuracy of the power grip and pulp pinch was relatively higher than that of the side pinch, and the electromyographic activity of intrinsic hand muscles exhibited a similar trend for power grip and side pinch, while the opposite muscle recruitment pattern was observed for pulp pinch. The increment of DLPFC oxygenation across force levels differed among grasping forms, with greater activity at relatively higher levels in the power grip and side pinch, and at relatively lower levels in the pulp pinch. Taken together, the differential contribution of the DLPFC may be responsible for force generation depending on different grasping forms and force levels.

Individuals with chronic ankle instability show altered regional activation of the peroneus longus muscle during ankle eversion.

Individuals with chronic ankle instability (CAI) present muscular weakness and potential changes in the activation of the peroneus longus muscle, which likely explains the high recurrence of ankle sprains in this population. However, there is conflicting evidence regarding the role of the peroneus longus activity in CAI, possibly due to the limited spatial resolution of the surface electromyography (sEMG) methods (i.e., bipolar sEMG). Recent studies employing high-density sEMG (HD-sEMG) have shown that the peroneus longus presents differences in regional activation, however, it is unknown whether this regional activation is maintained under pathological conditions such as CAI. This study aimed to compare the myoelectric activity, using HD-sEMG, of each peroneus longus compartment (anterior and posterior) between individuals with and without CAI. Eighteen healthy individuals (No-CAI group) and 18 individuals with CAI were recruited. In both groups, the center of mass (COM) and the sEMG amplitude at each compartment were recorded during ankle eversion at different force levels. For the posterior compartment, the sEMG amplitude of CAI group was significantly lower than the No-CAI group (mean difference = 5.6% RMS; 95% CI = 3.4-7.6; p = 0.0001). In addition, it was observed a significant main effect for group (F1,32 = 9.608; p = 0.0040) with an anterior displacement of COM for the CAI group. These findings suggest that CAI alters the regional distribution of muscle activity of the peroneus longus during ankle eversion. In practice, altered regional activation may impact strengthening programs, prevention, and rehabilitation of CAI.

Effects of Rosa roxburghii Tratt seed on the growth performance, meat quality, and sensory evaluation characteristics in growing rabbits

The objective of this study was to observe the effects of Rosa roxburghii Tratt seed (RRTS) on growth performance, meat quality, and sensory characteristic parameters in rabbits. Ninety-six New Zealand White rabbits were allotted to four dietary treatments containing 0 (CON), 120 (LR), 240 (MR), and 360 mg/kg (HR) RRTS. The experimental period lasted for 11 weeks. Thirty-two fattened rabbits were slaughtered, and the Longissimus thoracis et lumborum (LTL) muscle was used for analyses. The feeding of RRTS was significantly (P < 0.05) decreased the feed conversion ratio (FCR). pH45min, pH24h, lightness, redness, drip loss, and percentage of water loss were unaffected (P > 0.05) by dietary treatments, whereas MR and HR treatments resulted in lower (P < 0.05) levels of yellowness and higher (P < 0.05) levels of shear force. LR showed significantly higher (P < 0.05) meat polyphenol compounds and vitamin E relative to the CON. Moreover, compared to the CON, HR treatment showed significantly higher (P < 0.05) vitamin C and glutathione peroxidase, and LR and MR displayed lower (P < 0.05) superoxide anion radicals, and all treatments had higher levels catalase (CAT). C18:2n-6 t, C20:2, C20:3n-6, C20:4n-6, C20:5n-3, C22:5n-3, and C22:6n-3 in LTL meat were higher (P < 0.05) in MR than CON rabbits. Moreover, the LTL muscle sensory evaluation parameters of appearance and fibrousness were improved (P < 0.05). Overall, dietary supplementation with RRTS is a valid strategy for decreasing FCR, and improving meat CAT concentration, C20:5n-3 and C22:5n-3 profiles, and sensory characteristics parameters of rabbits.