Rotation Test Research Articles

Endurance Behavior of Cemented Tibial Tray Fixation Under Anterior Shear and Internal-External Torsional Shear Testing: A New Methodological Approach

BackgroundEarly total knee arthroplasty failures continue to surface in the literature. Cementation technique and implant design are two of the most important scenarios that can affect implant survivorship. Our objectives were to develop a more suitable preclinical test to evaluate the endurance of the implant-cement-bone interface under anterior shear and internal-external (I/E) torsional shear testing condition in a biomechanical sawbones. MethodsImplants tested included the AS VEGA System PS and the AS Columbus CR/PS (Aesculap AG, Germany), with zirconium nitride (ZrN) coating. Tibial implants were evaluated under anterior shear and I/E torsional shear conditions with 6 samples in 4 test groups. For the evaluation of the I/E torsional shear endurance behavior, a test setup was created allowing for clinically relevant I/E rotation with simultaneous high axial/tibio-femoral load. The test was performed with an I/E displacement of ±17.2°, for 1 million cycles with an axial preload of 3,000 N. ResultsAfter the anterior shear test an implant-cement-bone fixation strength for the AS VEGA System tibial tray of 2,674 ± 754 N and for the AS Columbus CR/PS tibial tray of 2,177 ± 429 N was determined (P = .191). After I/E rotational shear testing an implant-cement-bone fixation strength for the AS VEGA System PS tray of 2,561 ± 519 N and for the AS Columbus CR/PS tray of 2,824 ± 515 N was resulted (P = .39). ConclusionBoth methods had varying degrees of failure modes from debonding to failure of the sawbones foam. These two intense biomechanical loading tests are more strenuous and more representative of clinical activity.

Mental rotation with colored cube figures

Men usually outperform women in psychometric mental rotation tests with cube figures. This advantage could be pronounced due to the male stereotyped rotational objects. The present study aims to investigate whether gender differences in favor of men are absent when the stimuli are less male stereotyped. Therefore, 112 participants solved three psychometric mental rotation tests with cube figures colored in pink, blue, and grey. Men outperformed women independent of stimulus color. In the pink and the grey version of the test, participants with beliefs of spatial abilities as masculine performed better than those with feminine beliefs. The mental rotation test performance with pink figures was predicted by gender and gender stereotypes in spatial abilities. In the blue and grey version, gender and self-rated spatial abilities predicted the performance. It can be assumed that the stereotype activation by stimulus color was not sufficient to influence the performance.

Assessment of metal leaching from rediset-polymer modified asphalt binder on groundwater and soil contamination

Road pavement is a structure that expose to various climate conditions. To make it more durable, modification of asphalt binder with polymer is a popular option. However, to maintain the environmental sustainability, the mixing and compaction temperature needs to be reduced. Warm Mix Asphalt additive had been widely used for this purpose. In this research, the impact of a polymer modified asphalt binder, PG76 together with a chemical WMA additive, Rediset on groundwater and soil contamination was investigated. The effect of Rediset on PG76 in terms of viscosity and activation energy was also studied via the rotational viscosity test. Even though it was found that Rediset might affect the viscosity of PG76, the activation energy shows independent values. ATR-FTIR was employed to understand the reaction between these two substance. It was found that there had been no chemical reaction between PG76 and Rediset. As a complementary, AFM was utilised to observe the surface characteristics at micro-scale. It appeared that Rediset did contribute to the binder’s surface morphology. Finally, the modified tank leaching test together with analysis by ICP-MS, discovered that after 64 days submerged under flood, Rediset-PG76 had no effect on the adjacent water source and soil.

Detection of balance disorders using rotations around vertical axis and an artificial neural network

Vestibular impairments affect patients' movements and can result in difficulties with daily life activities. The main aim of this study is to answer the question whether a simple and short test such as rotation about a vertical axis can be an objective method of assessing balance dysfunction in patients with unilateral vestibular impairments. A 360˚ rotation test was performed using six MediPost devices. The analysis was performed in three ways: (1) the analytical approach based only on data from one sensor; (2) the analytical approach based on data from six sensors; (3) the artificial neural network (ANN) approach based on data from six sensors. For approaches 1 and 2 best results were obtained using maximum angular velocities (MAV) of rotation and rotation duration (RD), while approach 3 used 11 different features. The following sensitivities and specificities were achieved: for approach 1: MAV—80% and 60%, RD—69% and 74%; for approach 2: 61% and 85% and RD—74% and 56%; for approach 3: 88% and 84%. The ANN-based six-sensor approach revealed the best sensitivity and specificity among parameters studied, however one-sensor approach might be a simple screening test used e.g. for rehabilitation purposes.

Reduced Gain and Shortened Time Constant of Vestibular Velocity Storage as a Source of Balance and Movement Sensitivities in Gravitational Insecurity.

Gravitational insecurity (GrI) involves lifetime movement and balance concerns whose pathophysiological origins are unclear. We tested whether balance symptoms in mild GrI might involve anomalies in vestibular velocity storage (VVS), a brainstem/cerebellar circuit that amplifies gain and prolongs the persistence of weak vestibular signals from small/slow head movements. A Provisional Gravitational Insecurity Index (PGrI) was developed, evaluated for psychometrics/demographics, and used to identify otherwise healthy adults with life-long balance challenges as well as sex, age, and ethnicity-matched comparison adults without such challenges. Balance confidence, sensory hypersensitivities, spatial orientation, anxiety, and hearing loss were self-reported. Standing balance under visual/proprioceptive restrictions and perrotary vestibulo-ocular nystagmus were evaluated. The PGrI showed approximated test-retest reliability and convergent and discriminant validity. When only vestibular input was available, mild GrI participants on a tilting platform used effortful hip strategies for balance significantly more than did comparison participants. Rotation testing revealed that mild GrI participants had significantly less low frequency gain and shortened VVS persistence. Combined, these two parameters correlated significantly with PGrI. The PGrI also correlated with problematic spatial orientation, but surprisingly, not to anxiety. Balance/movement issues in GrI are likely due to VVS deficiencies. Additional mechanisms may account for other GrI symptoms. Better understanding of GrI's pathophysiological basis will be useful in informing the larger health-provider community about this condition.

Мануальная диагностика нарушений биомеханики в позвоночно-двигательных сегментах С1-С2 и С2-С3 при цервикогенной головной боли и мигрени

One of the main etiological factors of cervicogenic headache (CGH) is a violation of the biomechanics of the cervical spine (CS), mainly in the joints of the three upper cervical vertebrae (C1, C2, C3). To identify motion restriction in patients with CGH, a so-called flexion–rotation test has been proposed, which makes it possible to assess the limitation of the mobility of the atlantoaxial joint (C1-C2), which occurs on the side of the headache. Also, this test has been proposed for the differential diagnosis of CGH and migraine.
 Since the sources of CGH can be both the C1-C2 and C2-C3 joints, we proposed an alternative test – the test for lateral side bending and rotation in the C1-C2 and C2-C3 joints. During this test, the occlusion of movements in the joints below the C1-C2 spinal motion segment is achieved not by bending the neck, but by side bending in the C2-C3 joint. We used this test for both CGH and migraine.

Enriching Anatomy Learning with Virtual Reality Clinical Scenarios

IntroductionThe use of virtual reality (VR) to simply display anatomical specimens typically fails to exploit the potential of VR to enhance the learning environment. For example, anatomy education normally occurs within the confines of a laboratory which is devoid of relevant context, while VR is uniquely capable of providing a clinically‐relevant space that may enhance the anatomy learning experience. However, it is also possible that an enriched VR environment may inhibit learning, perhaps as a result of increased cognitive load. In general, well‐designed educational materials create schemas and organize the acquired knowledge in a way that promotes deeper learning, retention, and easy retrieval in other settings. Efforts must be made, in instructional design, to reduce extraneous and increase germane cognitive load, but how exactly this is done in VR remains an open question.ObjectiveThe purpose of this study is to evaluate the educational efficacy of a VR module which includes a clinical scenario presented in an immersive, contextually‐relevant virtual environment.HypothesisAlthough learning in a VR enriched environment with a clinical scenario can increase extraneous cognitive load, we hypothesize that it will ultimately facilitate memorization of anatomical structures, when compared with using 3D‐printed physical models or an interactive, 2D environment.MethodsParticipants with no prior knowledge of pelvic anatomy will be randomly assigned to one of three groups to learn human pelvic anatomy in an identical module presented in VR, an interactive 2D computer‐based module, or physical environment consisting of 3D‐printed models. Prior to the learning phase, participants will complete the Mental Rotation Test (MRT), as well as the Titmus Fly and Titmus Circles tests to assess spatial visualization ability and stereoscopic vision, respectively. They will then complete a pre‐test assessment where they will be asked to identify anatomical structures labeled on a 3D‐printed model. Participants will then be given 10 minutes to learn and memorize pelvic anatomy using their assigned anatomy modality. This will be followed by a post‐test assessment with another set of labeled structures to identify. Finally, participants will complete a survey to share feedback on the learning experience and will complete the Simulation Task Load Index (SIM‐TLX) questionnaire to assess cognitive load.ConclusionThe impact of contextually‐relevant enriched virtual environments and clinical scenarios for VR‐based anatomy education have yet to be explored. The findings from this study will provide valuable insight to inform the design of future VR learning tools that not only reduce or limit factors which can impair learning, but also suggest factors within the learning environment which have the potential to improve anatomy learning.

Does Online Anatomy Course Delivery Improve Visuospatial Ability in Novice Learners?

IntroductionThe study of anatomy can be challenging for students, as complex anatomical and spatial relationships can be difficult to master, particularly in virtual learning environments. Having good visuospatial ability (VSA) can be important for students to have in order to help them understand complex three‐dimensional relationships. There is evidence that learning anatomy in‐person can improve an individual's VSA and that those with higher VSA perform better in anatomy courses. However, no research has explored what effect learning anatomy in a completely virtual environment has on VSA. Thus, the first aim of this study is to determine if there are changes in VSA with online anatomy instruction in novice learners over one semester, and second, to examine if those with higher VSA interact differently with online resources. For our first aim, we hypothesize there will be an overall improvement in VSA over the course of the semester. Our second aim will be analyzed at a later date.MethodsFirst‐year undergraduate anatomy students at the University of Toronto were recruited for this study (n = 253). At the beginning of the semester in September 2021, before learning anatomical content, participants completed the redrawn Vandenberg and Kuse Mental Rotations Test (MRT‐A) which consisted of 24 questions. For the MRT‐A, participants were presented with a target figure and four stimulus figures, where two were a match to the target figure, but had been rotated. If both stimulus figures chosen were correct, one point was rewarded, for a total of 24 points and the full scores calculated out of 100 (24/24). In December 2021, another MRT‐A test will be administered, along with an online questionnaire that will ask students about what type of resources they used throughout the semester and how often they were used. In January 2022, focus groups will be conducted to gain a more in‐depth understanding into which learning tools students found most useful and why, along with how they were being used.ResultsPreliminary results indicate an initial mean score of 35.20 ± 17.54 with a median of 33.33. Students that scored below the median were categorized as low VSA (n = 112) and those who scored above were categorized as high VSA (n = 140). Additionally, the mean of students that identify as male had a mean of 40.55 ± 18.14 (high VSA = 83; low VSA = 39), those who identify as female had a mean of 30.03 ± 29.17 (high VSA = 55; low VSA = 70), and those who identify as non‐binary or chose “Prefer not to say” had a mean of 31.25 ± 17.14 (high VSA = 2; low VSA = 2). There was a significant difference between the mean score for males and females (p<0.001), but not for any other comparison.ConclusionsInitial results appear to be in line with previous research suggesting that males have higher VSA than females. Future analyses will provide a more in‐depth evaluation of overall changes in VSA, gender VSA changes, and the type of resources students engaged with during their online anatomy course. This research may be used as a baseline for further studies exploring course delivery in‐person, mixed, and remote to help instructors create equitable learning environments for students with differing VSA. Additionally, this research will help inform the development of an anatomy learning toolkit that will be used to help leaners develop better spatial reasoning skills.

Student Approach to Learning and Visuospatial Ability as Independent Predictors of Academic Performance in Human Anatomy

Several indices have been investigated for their accuracy as predictive metrics of students’ performance in anatomy courses. Both student approaches to learning (SAL) and visuospatial ability (VA) have been shown to be predictive of learning outcome achievement. However, far less anatomy‐specific evidence exists for SAL than for VA, and their respective predictive strength has yet to be examined.The present study investigated the relationship between SAL and VA as predictive metrics for student academic performance, as measured by laboratory‐based assessments. In addition, the predictive strength of each metric was evaluated to determine which of the two was most effective at quantitatively assessing anatomy learning environments. It was hypothesized that the variation in grades could be partially explained by both SAL and VA, and that the latter would have a stronger relationship to performance.Undergraduate students enrolled in an anatomy course at McGill University were surveyed for this study (total n = 138; 76.8% female; average years of age = 19.46, SD = ±1.04). Students were from kinesiology (58.0%), physical therapy (19.6%), occupational therapy (19.6 %), and other (2.9%) programs. In addition to collecting demographic data, the survey included the Revised 2‐factor Study Process Questionnaire to collect SAL on deep and surface scales, and the Mental Rotations Test to quantify VA.A multiple linear regression model was used to assess deep and surface approach to learning scores and VA as covariates that influence grades, while controlling for age, sex, and program of study [F(6,131) = 7.741, P < 0.001, adjusted R2 = 0.228]. Data analyses revealed that both VA (β = 0.802, SEM = 0.284; P = 0.006) and deep approach scores (β = 0.776, SEM = 0.246; P = 0.002) had significant positive correlations with grades; however, surface approach scores (β = ‐0.399, SEM = 0.280; P = 0.157) were not significantly correlated at P ≤ 0.05. Based on the coefficients, a one‐point increase on the deep approach scale was slightly more beneficial than the same point‐increase on the Mental Rotations Test; however, the advantage was minimal (+0.026%).These findings assert that SAL and VA can independently predict performance on laboratory‐based assessments in human anatomy – with VA representing a personal presage factor, and SAL representing a process factor. A deeper understanding of these metrics allows for better quantitative assessment of success when implementing curricular changes intended to improve anatomy learning environments. Therefore, both metrics should be used for a more comprehensive approach to evaluating educational interventions in anatomy.

Do Our Hands See What Our Eyes See: Investigating the Relationships Between Spatial and Haptic Abilities

IntroductionSpatial abilities (SA) are the cognitive ability to manipulate mental images of objects to problem solve and are linked to comprehension of three‐dimensional (3D) spatial knowledge in gross anatomy and in learning clinical procedures. Similarly, haptic abilities (HA) refer to translating tactile information from the immediate environment into mental images and are involved in handling anatomical specimens and technical skill acquisition common to clinicians. Both abilities independently play an important role in learning anatomy, yet the relationships between SA and HA are unknown. The objective of this study is to explore SA‐HA interactions.MethodsThe Mental Rotations Test (MRT) and the newly developed haptic abilities test (HAT) respectively quantified SA and HA in undergraduate students. The HAT, modelled after the MRT, consisted of untimed, matching questions utilizing MRT‐styled 3D handheld wooden objects (~10cm3) under three sensory conditions using sight (S), haptics (H) and the combination of both sight and haptics (SH). While HAT condition scores and response times determined accuracy, video recorded subject gaze and haptic behaviours on a question‐by‐question basis. Scores for MRT are presented as mean ± SD and HAT scores as median (Q1‐Q3).ResultsSubjects (n=16, 10F, 20‐28yrs) completed the MRT and HAT and were categorized into high (n=9, 4F, MRT: 14.8±3) and low (n=7, 6F, MRT: 6.3±3) (H/LSA) groups (p<0.0001). Scores obtained in the H condition [14 (13‐15) vs14 (14‐14), p=0.0031] were significantly lower than in the S [15 (15‐15) vs14 (14‐15)] and SH conditions [15 (15‐15) vs14 (14‐15)] in H/LSA groups respectively. Spearman’s correlation coefficient illustrated MRT scores were moderately related in the S condition (r=0.506, p=0.038), but unrelated in the SH and H conditions (SH: r=0.325, p=0.203; H: r=0.162, p=0.534). The number of pupillary fixations per question was similar (S:6.0±3.0 vs5.9±1.4, p=0.910; SH: 4.5±2.0 vs6.7±2.0, p=0.099) for H/LSA groups respectively. Initial descriptive analyses of hand behaviours (n=4) suggest H/LSA objects differently.DiscussionDespite significant difference in SA, when individuals are presented identical environmental 3D objects to view, view and touch, or touch alone, it is difficult to differentiate SA. These data suggest that the addition of haptic sensory information may aid LSA individuals completing spatial tasks. Although visual attention and timing of haptic behaviours may be similar between H/LSA subjects, further kinematic analysis of haptic strategies may be more meaningful to isolate how somatosensory inputs aid problem solving behaviours in LSA persons. This is some of the first data to simultaneously measure hand and gaze behaviour during spatially challenging tasks in individuals with divergent SA. Given recent migrations to online anatomy teaching and learning environments due to COVID‐19, understanding learner behaviour when sensory inputs, like haptics, are removed is valuable evidence that can inform future anatomy curriculum and resource development.

Preventive measures of fretting wear in railway axle bearings: Combined effect of grooving and amorphous carbon coating towards their backing rings

Fretting wear is surface damage caused by repeated slight relative slips between two contact surfaces. In railway applications, the fretting wear may occur between the inner ring and the backing ring of an axle journal tapered roller bearing. The authors found that a nonuniform pressure distribution between the inner ring and the backing ring deteriorates the fretting wear; a backing ring grooved on its oil seal sliding surface has been proposed to attain a uniform distribution in the radial direction. In this paper, to further reduce the fretting wear, we have conducted a rotation test on a full-scale railway axle bearing with the backing ring both coated its contact surface to the inner ring with diamond-like carbon (DLC) film and grooved its outer surface, and investigated the combined effect of these two approaches on the fretting wear prevention. We have found that the wear prevention effect is superior to the backing ring with only DLC film, but partial decohesion of the DLC film occurs. It is conceivable that the DLC film delaminated from the contact surface of the backing ring due to the locally increased contact pressure between them, even though the grooved backing ring relaxed the contact pressure. We, therefore, conclude that the combined effect of the above approaches is not very apparent. To improve the combined effect of “the grooving” and “the conventional continuous DLC coating,” preventing the decohesion of the DLC film is a challenge. Additionally, we recommend that a continuous structured film be selected as hard film coating the grooved backing ring, which has higher bonding strength than DLC film and a lower friction coefficient.

Mutual learning differential particle swarm optimization

This study proposes a mutual learning strategy to develop a high performance hybrid algorithm based on particle swarm optimization and differential evolution. In the mutual learning strategy, the position information in PSO subswarm is employed for DE mutation, and the DE individuals are used to construct learning exemplar for PSO subswarm together with particles’ historical best position. A novel elite DE mutation is proposed to speed up the convergence rate of DE subswarm. Based on mutual learning technique, the mutual learning differential evolution particle swarm optimization (MLDE-PSO) is proposed. To evaluate the performance of MLDE-PSO, three groups of test functions are employed, namely thirteen basic functions, thirteen rotated basic functions and thirty CEC2017 functions. The test results are compared with three state-of-the-art PSO algorithms, three recently PSO algorithms and DE/rand/1. The test results indicate that the proposed MLDE-PSO performs better than the other seven comparison algorithms, especially on rotated functions and CEC2017 functions. The rotation test shows that MLDE-PSO is not very sensitive to rotation transformation.

In vivo magnetic resonance imaging study of the hip joint capsule in the flexion abduction external rotation position

Although the flexion abduction external rotation (FABER) test is a useful hip provocation test, hip soft tissue characteristics in the FABER position remain unclear. This study investigated the in-vivo joint capsule characteristics, including its articular cavity area and relation to the fat pad surrounded by the joint capsule and pericapsular muscles, in the FABER position using magnetic resonance imaging. Thirteen hips from 13 healthy volunteers were analyzed. The images were obtained, with the participant hips at 15°-extension, 45°-flexion, and in the FABER position, to analyze the articular cavity size and fat pad and calculate these ratios to size of the femoral neck. The articular cavity area and its ratio to the femoral neck were significantly greatest in the FABER position, followed by those in the hip flexion and extension. Additionally, the area of the fat pad in the inter-pericapsular muscle space and its ratio to the femoral neck in the FABER position were significantly larger than those in the hip flexion and, as a tendency, larger than those in hip extension. To the best of our knowledge, this is the first in-vivo study to show the interrelationship among the joint capsule, pericapsular muscles, and fat pad in the FABER position.

Promoting Spatial Language and Ability Among SLD Children: Can Robot Programming Make a Difference?

Spatial language and ability play important roles in children’s cognitive development. Spatial ability in kindergarten predicts achievement in reading, math, science, and technology in primary school and therefore constitutes an important skill set in preparation for school entrance. Good spatial thinking skills are required for learning in school. The study’s purpose was to examine the contribution of robot programming to an intervention aimed at promoting spatial language (spatial vocabulary) and spatial ability (mental rotation, visual-spatial memory) among preschool children at risk for Specific learning disability (SLD). The sample of 84 preschool children participating in the study was randomly assigned to three groups: (1) intervention group with robot programming, (2) intervention group without robot programming, and (3) a control group. The findings indicate that children exposed to the robot-based intervention exhibited the greatest improvement in spatial vocabulary and mental rotation tests when compared to the children who participated in either the intervention without robot programming or in the control group. No significant differences between the groups were found in post-intervention visual-spatial memory. The findings indicate that robot programming activity contributes unique added value in attempts to foster spatial vocabulary and mental rotation.

A study on beam-to-column moment-resisting timber connections under service load, comparing full-scale connection testing and mock-up frame assembly

A new timber frame structural system consisting of continuous columns, prefabricated hollow box timber decks and beam-to-column moment-resisting connections is investigated. The hollow box timber decks allow long spans with competitive floor height and efficient material consumption. To achieve long spans, semi-rigid connections at the corners of deck elements are used to join the columns to the deck elements. In the present paper, experimental investigations of a semi-rigid moment-resisting connection and a mock-up frame assembly are presented. The semi-rigid connection consists of inclined screwed-in threaded rods and steel coupling parts, connected with friction bolts. Full-scale moment-resisting timber connections were tested under monotonic and cyclic loading to quantify rotational stiffness, energy dissipation and moment resistance. The mock-up frame assembly was tested under cyclic lateral loading and with experimental modal analysis. The lateral stiffness, energy dissipation, rotational stiffness of the connections and the eigen frequencies of the mock-up frame assembly were quantified based on the experimental tests in combination with a Finite Element model, i.e., the model was validated with experimental results from the rotational stiffness tests of the beam-to-column connections. Finally, the structural damping measured with experimental modal analysis was evaluated and compared with FE model using the material damping of timber parts and equivalent viscous damping of the moment-resisting connections.

Investigation of hand functions in individuals with cannabis and its derivatives use disorder.

The present study was aimed to compare the grip/pinch strengths and manual dexterity of individuals with and without the use of cannabis and its derivatives. A cross-sectional prospective study was conducted with 66 individuals, including 33 cases with the use of cannabis (and its derivatives) and 33 age- and sex-matched controls. Grip and pinch strengths were evaluated with a dynamometer. The Nine-Hole Peg Test (9HPT), Minnesota Manual Dexterity Test (MMDT), and Michigan Hand Outcomes Questionnaire (MHQ) were used to assess the hand function. The hand grip strength and dominant hand 2-point pinch (2PP) grip strength were less in individuals with substance use disorder (SUD) (p < 0.05). The 9HPT duration of the SUD patients was higher (p < 0.05). On the other hand, the MMDT insertion and rotation test results were different between the groups (p < 0.05). Grip strength was related with the MMDT insertion and rotation tests (r = -0.411 to -0.480). There was significant correlation between grip strength with dominant hand 9HPT (r = -0.370) and between dominant hand 3-point pinch (3PP) strength with MMDT insertion (r = -0.378). In addition, dominant hand 2PP strength was correlated with overall hand function of MHQ (r = 0.382). The individuals with cannabis use disorder showed reduced grip strength on both sides and decreased 2PP strength on the dominant side compared to healthy individuals. In addition, there is a decrease in the hand skills of individuals with cannabis use disorder. Decreased grip strength of individuals with cannabis use disorder affected their hand skills negatively.

Rotational flexural strength of cylindrical brittle specimens

AbstractConventional static flexural strength testing of brittle cylindrical rods only subjects a small fraction of the entire specimen's area or volume to the maximum tensile stress. Thus, a nonconservative measured strength likely results since most flaws on the surface or in the bulk are not subjected to a sufficiently high tensile stress that can cause fracture. To mitigate this, a rotational flexural tester and corresponding test method were developed whereby rotation and monotonically increasing three‐point flexure were superimposed to investigate fracture response of solid glass cylinders. This combination of rotation and flexure subjects more area and volume of a cylindrical test specimen to tensile stress than a standard static (nonrotating) flexural test. As anticipated, failure stresses were lower for the rotational flexural test. Expressions for effective area and volume are provided for rotating solid rods and tubes subjected to three‐point, four‐point, uniform, and uniformly distributed load bending configurations.

Experimental investigation of the rheological and phase change behavior of adipic acid as a phase change material (PCM) for thermal energy storage at 150 °C

Phase change materials (PCM) can store and release thermal energy mostly through a transition from solid to liquid and vice versa. This transition and its related parameters such as melting point, enthalpy and heat capacity were most often studied from a thermodynamic point aspect. Investigating the phase transition from a rheological point of view can provide us with important information such as viscosity change during the transition and in the melt. Considering the importance of natural convection during the melting of a PCM, the rheological knowledge can improve the estimations resulting from the numerical analysis of a phase change transition. However, there are a few studies on rheological behavior of PCMs. Here, the rheological behavior of an organic PCM, adipic acid, is studied. This PCM melts at 150 °C which corresponds to a medium temperature range for application in industrial waste heat recovery. Rotational and oscillatory tests under thermal insulation have been performed using a controlled stress rheometer and a plate geometry. Finally, the heat flow measured by Differential Scanning Calorimetry (DSC) is compared to the rheological oscillatory test results to provide a detailed information of phase transition range. To the authors best knowledge, this study is the first study in the rheology of a PCM at medium to high temperature (150 °C).

Can Online Teaching of Radiographic Anatomy Replace Conventional On-Site Teaching? A Randomized Controlled Study.

Different modalities such as lectures, dissections, 3D models, and online learning are used for teaching anatomy. To date, online learning has been considered a useful additional didactic tool. This study aimed to compare veterinary students' performance in radiographic anatomy (radio-anatomy) after online or classroom-based teaching to assess the extent to which the two methods were interchangeable. Three strategies were compared in a cohort of 83 learners. Students were committed to online learning only, online learning with the use of specimen equine bones, or learning on conventional radiographs with specimen equine bones. At baseline (pre-test), scores from a mental rotation test and radio-anatomy knowledge test were similar between groups. After training (post-test), scores in mental rotation and radio-anatomy significantly increased by 6.7/40 units (95% CI: 5.2-8.2; p < .001) and 5.1/20 units (95% CI: 4.3-5.9; p < .001), respectively. There was no difference in scores for mental rotation and radio-anatomy knowledge between groups at post-test. Gender influenced the mental rotation, with men scoring significantly higher than women at pre-test (M = 23.0, SD = 8.8 vs. M = 16.5, SD = 6.9; p = .001) and post-test (M = 32.1, SD = 5.5 vs. M = 22.7, SD = 8.6; p < .001). However, radio-anatomy knowledge was not influenced by gender. These results suggest radio-anatomy teaching can be safely achieved with either conventional radiographs or online resources. This is of interest since, due to the COVID-19 outbreak, rapidly changing from on-site to online methods for teaching veterinary medical education proved necessary.

Constitutive modeling for cyclic responses of saturated soft clay under principal stress rotation induced by wave loads

A bounding surface model is proposed to reproduce the cyclic responses of saturated soft clay under principal stress rotation induced by wave loads. While extensively reported in experimental studies, this particular type of clay response has not been adequately addressed by constitutive modeling. By incorporating the mapping rules of relocatable projection center into the bounding surface, the plastic effects under pure principal stress rotation can be established. To represent the non-coaxiality during pure principal stress rotation, the presented model employs a non-coaxial flow rule sharing the same directions with the non-coaxial stress rate. However, it has been modified to related to the coaxial strain rate and the current stress ratio. Besides, the anisotropic elasticity is introduced for simulating the effects on plastic accumulation behavior during principal stress rotation. The developed model is validated through pure principal stress rotation tests of Shanghai clay and Wenzhou clay. The comparisons show that the proposed model can reasonably reproduce cyclic responses of saturated soft clay under principal stress rotation induced by wave loads.