Strain patterns in normal anterior talofibular and calcaneofibular ligaments and after anatomical reconstruction using gracilis tendon grafts: A cadaver study

Background Inversion ankle sprains, or lateral ankle sprains, often result in symptomatic lateral ankle instability, and some patients need lateral ankle ligament reconstruction to reduce pain, improve function, and prevent subsequent injuries. Although anatomically reconstructed ligaments should behave in a biomechanically normal manner, previous studies have not measured the strain patterns of the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) after anatomical reconstruction. This study aimed to measure the strain patterns of normal and reconstructed ATFL and CFLs using the miniaturization ligament performance probe (MLPP) system. Methods The MLPP was sutured into the ligamentous bands of the ATFLs and CTLs of three freshly frozen cadaveric lower-extremity specimens. Each ankle was manually moved from 15° dorsiflexion to 30° plantar flexion, and a 1.2-N m force was applied to the ankle and subtalar joint complex. Results The normal and reconstructed ATFLs exhibited maximal strain (100) during supination in three-dimensional motion. Although the normal ATFLs were not strained during pronation, the reconstructed ATFLs demonstrated relative strain values of 16–36. During the axial motion, the normal ATFLs started to gradually tense at 0° plantar flexion, with the strain increasing as the plantar flexion angle increased, to a maximal value (100) at 30° plantar flexion; the reconstructed ATFLs showed similar strain patterns. Further, the normal CFLs exhibited maximal strain (100) during plantar flexion-abduction and relative strain values of 30–52 during dorsiflexion in three-dimensional motion. The reconstructed CFLs exhibited the most strain during dorsiflexion-adduction and demonstrated relative strain values of 29–62 during plantar flexion-abduction. During the axial motion, the normal CFLs started to gradually tense at 20° plantar flexion and 5° dorsiflexion. Conclusion Our results showed that the strain patterns of reconstructed ATFLs and CFLs are not similar to those of normal ATFLs and CFLs.

Strain patterns in normal anterior talofibular and calcaneofibular ligaments and after anatomical reconstruction using gracilis tendon grafts: A cadaver study

BackgroundInversion sprains of the lateral ankle ligaments often result in symptomatic lateral ankle instability, and some patients need lateral reconstruction surgeries to reduce pain, improve function, and prevent subsequent injuries. Although anatomically reconstructed ligaments should behave in a biomechanically normal manner, previous studies have not measured the strain patterns of the anterior talofibular (ATFL) and calcaneofibular ligaments (CFL) after anatomical reconstruction. This study aimed to measure the strain patterns of normal and reconstructed ATFL and CFLs using a miniaturization ligament performance probe (MLPP) system.MethodsThe MLPP was sutured into the ligamentous bands of the ATFLs and CTLs of three fresh-frozen, lower extremity, cadaveric specimens. Each ankle was manually moved from 15° dorsiflexion to 30° plantar flexion, and a 1.2-N m force was applied to the ankle and subtalar joint complex.ResultsThe normal and reconstructed ATFLs exhibited maximal strain (100) during supination in three-dimensional motion. Although the normal ATFLs were not strained during pronation, the reconstructed ATFLs demonstrated relative strain values of 16–36. During axial motion, the normal ATFLs began to gradually tense at 0° plantarflexion, with the strain increasing, as the plantarflexion angle increased, to a maximal value (100) at 30° plantarflexion; the reconstructed ATFLs showed similar strain patterns. The normal CFLs exhibited maximum strain (100) during plantarflexion-abduction and relative strain measurements of 30–52 during dorsiflexion in three-dimensional motion. The reconstructed CFLs exhibited the most strain during dorsiflexion-adduction and demonstrated relative strain measurements of 29–62 during plantarflexion-abduction. During axial motion, the normal CFLs began to gradually tense at 20° plantarflexion and 5° dorsiflexion.ConclusionOur results showed that the strain patterns of reconstructed ATFLs and CFLs are not exactly the same as those in the normal ligaments.

Role of Electromechanical Coupling, Locomotion Type and Damping on the Effectiveness of Fish-Like Robot Energy Harvesters

In this work, an investigation into the influence of prescribed motion on a body caudal fin aquatic unmanned vehicle (AUV) energy harvester is carried out. The undulatory–oscillation locomotion inspired by fishes actuates a composite beam representative of a spinal column with a piezoelectric patch. Two patch configurations—one at the head and tail—are considered for the AUV energy harvester, with a length that would not activate a harmonic in the system. An electromechanical model which accounts for the strain of the prescribed motion and the induced relative strain is developed. Discretizing the relative strain using Galerkin’s method requires a convergence study in which the impacts of the prescribed motion, dependent on the undulation and envelope of the motion, are investigated. The combination of prescribed motion and structural terms leads to a coupling that requires multiple investigations. The removal of the undulation of the system produces a more consistent response. The performances of the two different patch configurations undergoing different prescribed motions are studied in terms of coupled damping and frequency effects. An uncoupled Gauss law-based model is adopted to compare the performance of our approach and that of the coupled electromechanical model harvester. It is demonstrated that there is a complex interaction of the phases of the prescribed and relative motions of the structure which can lead to the development or destruction of the response of the total motion or voltage for the system. The results show that the structural damping and type of locomotion are the most influential parameters on the validity of the uncoupled approach. It is also found that the optimal resistances for the coupled and uncoupled representations are the same for the two motions and patch configurations considered.

Study on Permeability of Deep-Buried Sandstone under Triaxial Cyclic Loads

The triaxial cyclic loading and unloading test was carried out on a TAW-2000 rock mechanics to study the permeability characteristics of deep-buried sandstone. This paper analyzed the evolution laws of permeability, elastic modulus, rock damage, dissipated energy, and acoustic emission events of sandstone under different confining pressures. It also introduced the concept of relative strain and further discussed the relationship between relative strain and permeability. The test results showed that the permeability of sandstone under cyclic loading and unloading obviously experienced three stages. At a low strain level, the damage degree of sandstone was low. As a result, both the number of acoustic emission events and the proportion of the dissipated energy density were small. In this stage, with increasing the stress, the permeability decreased. With the increase of the relative strain, the propagation of fissure increased through rock interior and the damage of rock was accumulated. Consequently, the number of acoustic emission events grew slowly, and the proportion of dissipated energy density and the damage variable (D) increased gradually. In this stage, the permeability increases. As the axial strain reached the peak strain, the fissures developed into cracks and the rock failure happened. The number of acoustic emission events increased rapidly; both the proportion of the dissipated energy density and the damage variable (D) obtain the maximum value. In this stage, the permeability increased greatly. In this study, the point of fissure propagation of rock specimens was used as the point of demarcation. Before the fissures propagated, the permeability increased slowly and it was in accordance with a linear function. After the fissures propagated, the degree of rock damage increased, and the permeability increased in the form of an exponential function. The larger the confining pressure was, the smaller the relative strain corresponding to the point of fissure propagation was.

Process modeling of sequential radial-direct extrusion using curved triangular kinematic module

In this article new engineering calculations such as the value of the relative strain pressure for the combination of a triangular kinematic module with external modules of various configurations are developed. This allowed us to describe qualitatively the nature of the metal flow in the reversal zone before radial extrusion. This made it possible to achieve a decrease in the predicted assessment of the power mode for the deformation process with comparison by the use of rectangular modules. The greatest reduction in the value of the relative strain pressure corresponded to a combination with an adjacent rectangular module (with the missing vertical component CPVF) and can obtain 7-8%. The deviation of the theoretical results in the power parameters of the process by using a triangular kinematic module are 12-15% for a process with a developed flow radial component. The resulting calculations can be used to model new cold extrusion processes.

The Effect of Different Thawing Rates on Cryopreserved Human Iliac Arteries Allograft’s Structural Damage and Mechanical Properties

Introduction. The rate of thawing of cryopreserved human iliac arteries allografts (CHIAA) directly affects the severeness of structural changes that occur during this process. Method. The experiment was performed on ten CHIAA. The 10% dimethylsulphoxide in 6% hydroxyethyl starch solution was used as the cryoprotectant; all CHIAA were cooled at a controlled rate and stored in the vapor phase of liquid nitrogen (-194°C). Two thawing protocols were tested: (1) placing the CHIAA in a water bath at 37°C, and (2) the CHIAA were thawed in a controlled environment at 5°C. All samples underwent analysis under a scanning electron microscope. Testing of the mechanical properties of the CHIAA was evaluated on a custom-built single axis strain testing machine. Longitudinal and circumferential samples were prepared from each tested CHIAA. Results. Ultrastructural analysis revealed that all five CHIAA thawed during the thawing protocol 1 which showed significantly more damage to the subendothelial structures when compared to the samples thawed in protocol 2. Mechanical properties: Thawing protocol 1—longitudinal UTS 2,53±0,47 MPa at relative strain 1,27±0,12 and circumferential UTS 1,94±0,27 MPa at relative strain 1,33±0,09. Thawing protocol 2—longitudinal ultimate tensile strain (UTS) 2,42±0,34 MPa at relative strain 1,32±0,09 and circumferential UTS 1,98±0,26 MPa at relative strain 1,29±0,07. Comparing UTS showed no statistical difference between thawing methods. Conclusion. Despite the significant differences in structural changes of presented thawing protocols, the ultimate tensile strain showed no statistical difference between thawing methods.

Feasibility of Relative Strain Index (RSI) for the Assessment of Heat Stress in Outdoor Environments: Case Study in Three Different Climates of Iran

Objectives: Different indices are used to evaluate heat stress in outdoor environments. This study was aimed at examining the applicability of the Relative Strain Index (RSI) to the assessment of heat stress in several climates of Iran. Methods: Based on the Köppen classification, three different climates were studied. Arak, Bandar Abbas, and Sari were selected as representative of semi-arid and cold climates, hot and dry, and Mediterranean, respectively. The data recorded by the meteorological organization, including air temperature, relative humidity and air velocity were surveyed during 15-year period in three different climates. The RSI index was calculated by the formula. Also, the Wet Bulb Globe Temperature (WBGT) index was computed using a model presented by the Australian Bureau of Meteorology (ABM). Data were analyzed using SPSS v.22, descriptive statistics, Pearson correlation coefficient, and linear regression. Results: The mean RSI index in summer of the 15 years in Arak was 0.033 ± 0.33, in Bandar Abbas 0.54 ± 0.6 and for Sari was 0.17 ± 0.05. A high correlation was found between environmental variables and RSI index in three different climates. As well, there was a positive and significant correlation between both RSI and WBGT indices in three different climates (R2>0.96). Conclusion: The RSI index is a simple and empirical index and can be used for the evaluation of heat stress along with other indices. The index estimates the situation more than expected to be stressful in warm and dry conditions. So, it is not a useful index for hot and dry climates such as Bandar Abbas.

Complete Coding Sequence of a Novel Bluetongue Virus Isolated from a Commercial Sheeppox Vaccine

The full genome sequences of two isolates of bluetongue virus (BTV) from a commercial sheeppox vaccine were determined. Strain SPvvvv/02 shows low sequence identity to its closest relative, strain BTV-26 KUW2010/02, indicating the probable detection of a novel BTV genotype, whereas strain SPvvvv/03 shows high sequence identity to strain BTV-28/1537/14.

Evaluation of Strains and Thicknesses of Pipe Elbows on the Basis of Expressions Resulting from the Eudirective for the Case of Large and Small Deformations

The relations to calculate the maximum value of strains in processes of bending tubes on benders, in stretched layers of tubes, are presented in this work on the basis of the EU-Directive concerning production of pressure equipment. It has been shown that for large deformations that occur during bending of the pipes on knees, logarithmic strain measures (real) and relative strain measures give different values of strain but equal wall thicknesses in the bending zone. Logarithmic measures are frequently used in engineering practice and are valid for large and small deformations. Reverse expressions were also derived to calculate the required initial wall thickness of the tube to be bent, in order to obtain the desired wall thickness of the knee after bending.