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This review identifies the three-dimensional knee loads that have the highest risk of injuring the anterior cruciate ligament (ACL) in the athlete. It is the combination of the muscular resistance to a large knee flexion moment, an external reaction force generating knee compression, an internal tibial torque, and a knee abduction moment during a single-leg athletic manoeuvre such as landing from a jump, abruptly changing direction, or rapidly decelerating that results in the greatest ACL loads. While there is consensus that an anterior tibial shear force is the primary ACL loading mechanism, controversy exists regarding the secondary order of importance of transverse-plane and frontal-plane loading in ACL injury scenarios. Large knee compression forces combined with a posteriorly and inferiorly sloped tibial plateau, especially the lateral plateau-an important ACL injury risk factor-causes anterior tibial translation and internal tibial rotation, which increases ACL loading. Furthermore, while the ACL can fail under a single supramaximal loading cycle, recent evidence shows that it can also fail following repeated submaximal loading cycles due to microdamage accumulating in the ligament with each cycle. This challenges the existing dogma that non-contact ACL injuries are predominantly due to a single manoeuvre that catastrophically overloads the ACL.

Vertebral compression fractures (VCF) are frequent injuries mostly related to bone fragility[1][1] and are successfully treated by cementoplasty, such as vertebroplasty or kyphoplasty.[2 3][2] Vertebroplasty requires the use of two-dimensional (2D) imaging for intraoperative control of cement

This retrospective case series aimed to identify whether trans-articular screws, dorsal bridging plates or if a 4-corner compression plate offers better functional outcome after B2 Lis Franc injuries. Thirty-eight patients underwent surgical fixation for these injuries over five years in a Level 1 Trauma Centre. Patients were treated in 1 of 3 treatment arms: trans-articular screw, dorsal bridge plate, or 4-corner compression plate fixation. The primary outcome measures were the Manchester Oxford Foot and Ankle Questionnaire and the Euroqol- 5DL score and surgical results included postoperative complications and further surgery. Injury type, energy of mechanism, open versus closed status were not significantly different within any fixation group. We achieved 94.7% (n=36) good anatomical reduction. Finding significant improvement between plate fixation (both types) versus trans-articular screw groups treatment functional outcomes. A clinically crucial improvement in Manchester Oxford Foot & Ankle Questionnaire scores, and improved Euroqol- 5DL outcomes between 4-corner compression plate and trans-articular screw group. Overall, there was no significant difference in metalware failure, metalware removal and soft tissue complications. This study concludes that functional outcomes after Lis Franc fractures are not just dependant on the quality of anatomical reduction but are affected by fixation type. Further studies are required to provide qualitative analysis and assessment of dorsal bridge plate fixation versus 4-corner compression plate. Significantly, we have seen the 4-corner compression plate group reached the minimum clinically meaningful difference in the Manchester Oxford Foot and Ankle Questionnaire when compared to trans-articular screw fixation. Level of Clinical Evidence: 4

The structural behaviour of concrete-filled steel tubular columns subjected to full and local compression loads was investigated. Experiments were performed on 18 columns with different cross-sectional slenderness ratios. The experimental parameters were the local compression area ratio and the slenderness ratio. The strength index, stiffness and ductility index of the columns were obtained through experimental tests. The results revealed that the local compression area ratio and slenderness ratio are key parameters that considerably affect the strength capacity of columns subjected to full and local compression loads. Design models provided in various international codes and various studies were used to validate the experimental results. Furthermore, the suitability of these design models for predicting the strength capacity of columns subjected to full and local compression loads was examined. Finally, through regression analysis, a simplified design model was developed for predicting the strength capacity of columns under full and local compression loads.

Preforming process would change yarn angle and yarn orientation, its influence on the material properties and material orientations needs to be considered in the performance analysis. However, most current performance models fail to account for the preforming effect. An integrated performance model accounting for the impact of preforming has been developed in this research. In this integrated model, part geometry, yarn angle and orientation after preforming of multiple prepreg layers are predicted by Finite Element Analysis (FEA) using a non-orthogonal constitutive law. Experiments were conducted to validate the preforming simulation for a single dome composites structure made by two prepreg layers with different initial fiber orientations. Performance analysis until failure was then conducted for the single dome structure to validate the integrated performance model. Comparison between simulation and experiment shows that not only the failure mode and failure zone, but also the force-displacement curve during compression process are captured correctly by the performance model, demonstrating the effectiveness of the newly proposed model in accounting for the impact of preforming process.

Background Giant aneurysms of the intracranial vertebral artery are very rare cerebrovascular lesions. Due to the rarity of these aneurysms, we know little about them. Methods We performed a systematic review of the English literature by searching the PubMed database. The inclusion criteria were as follows: (a) the full text was available and (b) complete clinical data were available. Results A total of 45 articles were identified, containing 53 patients (53 aneurysms). The patients were aged from 5 to 77 years (48.8 ± 20.8 years). Four patients receiving conservative treatment died. The remaining 49 patients were divided into the aneurysm removal group ( n = 17) and the aneurysm reserve group ( n = 32). The outcomes of the 49 treated cases could be obtained in 45 cases, 31 of which (68.9%, 31/45) had a Glasgow outcome scale score of 4–5. Conclusions It is still difficult to treat intracranial giant vertebral artery aneurysms, regardless of the treatment selected. Because of the malignant natural history, aggressive treatment is still advocated.

Pressure therapy is widely used in the management of keloid mass and for preventing postexcision recurrence of earlobe keloid. Although various types of compression devices are available, the pressure applied by these devices is uncontrolled and associated with the risk of pressure necrosis. This article presents a novel design for a compression device with threaded connectors to control the amount and direction of the pressure applied on the keloid mass.

Background Focusing on compression fractures of bone by finite elements, we evaluated bone strength based on the computed tomography-based finite element method. However, the exposure dose is an issue. We aimed to investigate the quantity of reduction of the radiation dose with respect to the reference dose by comparing the calculation results of compression fractures of the vertebral body using experimental data obtained from the spine of a pig. Methods Computed tomography images of a self-made phantom that enclosed the lower lumbar vertebra of edible wild pigs were obtained under baseline-dose conditions using various lower tube currents. Images obtained under reference-dose conditions were reconstructed using the filtered back-projection method, whereas images obtained under low-dose conditions were reconstructed using both the filtered back-projection method and the iterative reconstruction method. Computer simulations involving the creation of finite element models using all images were implemented for the compression load calculation for vertebral body parts. Based on the calculated results, images of the low-dose and reference-dose conditions were compared. Results Using pigs’ lower lumbar vertebrae, finite element model analysis of low-dose X-ray computed tomography images showed that equivalent results can be obtained with a dose of approximately 40% of the standard radiographic reference doses. As for the compression stress intensity, the same results as those under reference-dose conditions were obtained using the iterative reconstruction method in combination with computed tomography-based finite element method. Conclusions The combination of the iterative reconstruction method with the computed tomography-based finite element method is an effective image reconstruction method for achieving dose reduction.

BACKGROUND: Some recovery strategies are needed to reduce or eliminate the effect of negative symptoms caused by exercise. OBJECTIVE: The aim of this study was to determine the effect of different types of recovery after single-bout strength exercises on biomarkers of muscle damage, cytokine release and lactate elimination. METHODS: Following familiarization, 10 male volunteers performed four randomized recovery protocols (passive or active recovery with or without compression garments) following a single bout of resistance exercise (squat and deadlift exercises). The blood creatine kinase (CK), lactate dehydrogenase (LDH), interleukine-6 (IL-6), and tumor necrosis factor-alfa (TNF-α) values were measured before and after exercise, and after 24, 48, 72 hours. RESULTS: The CK analysis showed that all protocols significantly increased (p< 0.05) CK activity compared to the pre and 24 h post time points. Interestingly, protocol 3 and 4 significantly decreased (p< 0.05) CK activity compared 24 and 72 h post-exercise. LDH, IL-6, and TNF values did not show significant difference (p> 0.05) at the time points tested. CONCLUSIONS: Active recovery is an effective method for reducing the severity and duration of muscle damage and for accelerating the clearance of blood lactate (BLa) following a single bout of strength training. There is no added benefit of using compression garments.

A diagnosis of lymphedema comes with a lifetime requirement for careful self-care and treatment to control skin deterioration and the consequences of excessive fluid and protein buildup leading to abnormal limb volume and an increased risk of infection. The burden of care and psychosocial aspects of physical disfiguration and loss of function are associated with compromised quality of life (QoL). The current standard therapeutic intervention is complex decongestive therapy with manual lymph drainage and frequent wearing of compression garments. With insurance limitations on therapy visits and the time and travel required, additional home treatment options are needed. Pneumatic compression pumps that mimic the manual massage pressure and pattern are sometimes prescribed, but these are bulky, difficult to apply, and require immobility during treatment. An open-label pilot study in 40 subjects was performed to evaluate the QoL and limb volume maintenance efficacy of a novel wearable compression system (Dayspring™) that is low profile, easy to use, and allows for mobility during treatment. After 28 days of use, subjects had a statistically significant 18% (

An interaction function was constructed based on the axial compression/tension and shear loads of orthotropic plates. The coefficients of the polynomial function were determined by uniaxial test results. Buckling interaction and failure interaction formulae under combined axial tension/compression and shear loads were established. Based on the uniaxial load test results of orthotropic plates, the buckling load and bearing capacity under any proportion of the combined loads could be predicted by using the proposed interaction formulae. The buckling interaction curves and failure envelopes predicted by the proposed interaction formulae were in excellent agreement with the test results.

External aortic compression has been investigated as a treatment for non-compressible truncal haemorrhage in trauma patients. We sought to systematically gather and tabulate the available evidence around external aortic compression. We were specifically interested in its ability to achieve hemostasis and aid in resuscitation of traumatic arrest and severe shock and to consider physiological changes and adverse effects. A scoping review approach was chosen due to the highly variable existing literature. We were guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, using the specific extension for scoping reviews. Searches were done on PubMed and Scopus databases in October 2020. We found that a range of studies have investigated external aortic compression in a variety of settings, including case reports and small case series, porcine hemorrhage models and effects on healthy volunteers. External aortic compression for postpartum hemorrhage in a single center provided some evidence of effectiveness. Overall the level of evidence is limited, however, external aortic compression does appear able to achieve cessation of distal blood flow. Furthermore, it appears to improve many relevant physiological parameters in the setting of hypovolemic shock. Application for more than 60 minutes appears to cause increasingly problematic complications. In conclusion we find that the role of external aortic compression warrants further research. The intervention may have a role as a bridge to definitive treatment of noncompressible truncal haemorrahge.

OBJECTIVE For same-day discharge lower extremity arterial disease (LEAD) endovascular procedures, femoral manual compression could be an alternative to arterial closure devices. The aim of this study was to assess the security and efficacy of same-day discharge after manual compression in patients treated for LEAD endovascular revascularization with 5F sheath. METHODS FREEDOM OP was a national multicenter, prospective, single arm study. Patients with symptomatic LEAD (Rutherford 2 to 5) and eligible for same-day discharge were included. The primary endpoint was the total in-hospital admission rate, which includes overnight surveillance and rehospitalization rate at 1 month. RESULTS Between September 2017 and August 2019, 114 patients were included. The mean age of the patients was 66 ± 10 years and most of them were claudicant (103; 94%). Mainly femoropopliteal lesions were treated (178; 70%) and the technical success was 97%. One hundred forty two 5F stents and fifty one 5F drug coated balloon were delivered. The mean manual compression duration was 13 ± 4 min. Major access-related complications rate was 4.5%. Total in-hospital admission rate was 11%. Seven patients had overnight surveillance and 5 were rehospitalized (2 for the target lesion). No rehospitalisation was carried out within 24 hours after discharge. No major cardiovascular event, including death, was observed. The patients were significantly improved in term of clinical status (p

A triangular configuration with three parallel cannulated screws is an established treatment for fixing transverse patellar fractures; however, the stability achieved with this approach is slightly lower than that attained with cannulated screws combined with anterior wiring. In the present study, triangular configurations were modified by partially or totally replacing the cannulated screws with headless compression screws (HCSs). Through finite element simulation involving a model of distal femoral, patellar, and proximal tibial fractures, the mechanical stability levels of the modified triangular configurations were compared with that of two cannulated screws combined with anterior wiring. Four triangular screw configurations were developed: three HCSs in a forward and backward triangular configuration, two deep cannulated screws along with one superficial HCS, and two superficial cannulated screws with one deep HCS. Also considered were two parallel cannulated screws (inserted superficially or deeply) combined with anterior wiring. The six approaches were all examined in full knee extension and 45° flexion under physiological loading. The highest stability was obtained with the three HCSs in a backward triangular configuration, as indicated by the least fragment displacement and the smallest fracture gap size. In extension and flexion, this size was smaller than that observed under the use of two deeply placed parallel cannulated screws with anterior wiring by 50.3% (1.53 vs. 0.76 mm) and 43.2% (1.48 vs. 0.84 mm), respectively. Thus, the use of three HCSs in a backward triangular configuration is recommended for the fixation of transverse patellar fractures, especially without the use of anterior wiring.

This paper demonstrates an experimental study on the possibility of producing lightweight concrete by utilizing the Attapulgite stone and the shear behavior of lightweight self-compacted concrete (LWSCC) beams exposed to axial load and bending load. Bending load is applied by two points load gradually until the beams reach failure. To investigate the impact of axial load on the structural behaviors of the (LWSCC) beams, specimens are prepared to have a various axial load of 100 KN, 150 KN, and 200 KN and shear span to depth ratio (a/d) of 2.5, 2.75, and 3.00. The findings demonstrated that the beams that have the smaller (a/d) are failed at the lower level of deflection comparison with others beams. Also, the findings demonstrated that the applied axial force delays the (LWSCC) beam failure it also works to change the failure mode of the beams from shear failure to shear compressive failure and concrete crushing failure since the compressive stresses in the upper part of the lightweight self-compacting concrete.

Ganglion cysts are fluid filled sacs which develop near joints and tendons and are usually asymptomatic. Lower limb ganglion cysts are rare occurrences especially those situated around joint spaces causing nerve compression. We present the case of a 68 year-old female with history of progressive swelling in the left antero-lateral leg, associated with pain, and neurological symptoms of peroneal nerve compression. Magnetic resonance imaging (MRI) revealed a large proximal tibiofibular joint ganglion cyst causing peroneal nerve compression. One year following the left sided presentation, the patient presented with similar but less severe symptoms in her right antero-lateral leg. MRI revealed a small juxta-articular ganglion cyst in the right proximal tibiofibular joint space. We discuss etiology, symptoms, and management of lower limb ganglion cysts.

This paper presents a novel framework of modeling crushable granular materials under mechanical loadings based on the discrete element method (DEM). The framework is featured with the construction of the one-to-one model in which every particle in a physical experiment has its own numerical twin and allows the modeling of irregular shaped fragments during the continuous breakage process. First, image processing techniques and spherical harmonic (SH) analysis were adopted, respectively, to segment and label particles and to construct a one-to-one model mathematically in DEM. Then, a particle crushing criterion based on the maximum interparticle contact force was used to predict the crushing events, showing fitting results that agreed very well with a large number of single particle crushing tests. Next, a statistical approach for the generation of particle fragmentation modes of a given type of sand particles based on the principal component analysis (PCA) was proposed. The aim of the PCA was to analyze the statistical trends of the coefficient matrix, which was composed of the SH coefficients of all the particles involved in the analysis. Finally, a successful modeling of a particle crushing event was achieved by replacing the particle, which was judged by the crushing criterion to undergo crushing, with a few subparticles chosen randomly from a specific fragment template constructed using the microcomputed tomography (micro-CT) data.

Lower back pain is one of the most common problems amongst people in this fast-paced life, often caused by degenerative disc diseases in the lumbar region of the spine. Many conventional techniques are commercially available in order to manufacture spinal cages; however, three-dimensional (3D) printing provides the flexibility of creating patient-specific spinal cages depending on the patient’s condition. Indeed, solid cages provide the strength but lack in reducing stress-shielding; hence, creating a porous structure inside the spinal cages can help in reducing the stress shielding effect. In the present work, two cages (solid and Gyroid structure porous plif) have been made of titanium ELI grade by using direct metal laser sintering (DMLS) technique. Compression and fatigue test has been performed in the simulated environment with the help of finite element analysis (FEA) and, thereafter, compared with the physical results. It has been found that Gyroid structured porous cage developed more concentration of the stress when compared to the solid cage; however, it efficiently reduced the stress shielding effect and will promote the bone in-growth.

Objective : To investigate the clinical efficacy and safety of the controlled distraction-compression technique using an expandable titanium cage (ETC) in posttraumatic kyphosis (PTK).Methods : We retrospectively studied and collected data on 20 patients with PTK. From January 2014 to December 2017, the controlled distraction-compression technique using ETC was consecutively performed in 20 patients with PTK of the thoracolumbar zone (range, 36–82 years). Among them, nine were males and 11 were females and the mean age was 61.5 years. The patients were followed regularly at 1, 3, 6, and 12 months, and the last follow-up was more than 2 years after surgery.Results : The mean follow-up period was 27.3±7.3 months (range, 14–48). The average operation time was 286.8±33.1 minutes (range, 225–365). The preoperative regional kyphotic angle (RKA) ranged from 35.6° to 70.6° with an average of 47.5°±8.1°. The immediate postoperative mean RKA was 5.9°±3.8° (86.2% correction rate, p=0.000), and at the last follow-up more than 2 years later, the mean RKA was 9.2°±4.9° (80.2% correction rate, p=0.000). The preoperative mean thoracolumbar kyphosis was 49.1°±9.2° and was corrected to an average of 8.8°±5.3° immediately after surgery (p=0.000). At the last follow-up, a correction of 11.9°±6.3° was obtained (p=0.000). The preoperative mean back visual analog scale (VAS) score was 7.9±0.8 and at the last follow-up, the VAS score was improved to a mean of 2.3±1.0 with a 70.9% correction rate (p=0.000). The preoperative mean Oswestry disability index (ODI) score was 32.3±6.9 (64.6%) and the last follow-up ODI score was improved to a mean of 6.85±2.9 (3.7%) with a 78.8% correction rate (p=0.000). The overall complication was 15%, with two of distal junctional fractures and one of proximal junctional kyphosis and screw loosening. However, there were no complications directly related to the operation.Conclusion : Posterior vertebral column resection through the controlled distraction-compression technique using ETC showed safe and good results in terms of complications, and clinical and radiologic outcomes in PTK. However, to further evaluate the efficacy of this surgical procedure, more patients need long-term follow-up and there is a need to apply it to other diseases.

A substantial amount of parametric analysis and testing is carried out in the design and construction process for a large transport aircraft to achieve an optimal structure. One of the damage tolerance design objectives of any large transport aircraft is a two bay crack arrest in a circumferential direction. In this crack arrest ability, the longeron static strength plays a dominant role. Thus, a parametric analysis of the efficiency of the longeron on the residual strength of a two-bay circumferential crack have been carried out in this study. One of the critical load cases that the fuselage has to effectively tolerate is internal pressurization. In the fatigue life estimation for the fuselage, the compression and decompression cycles are generally used as an input. Pressurization load cases are considered for the study in the present work. Analytical method is used to calculate the circumferential crack arrest capability in the stiffened panel by considering longitudinal stresses. The stress intensity factor (SIF) values obtained using finite element analysis (FEA) agree with the SIF values obtained by theoretical method.

Lateral restrainers are traditionally provided in reinforced masonry (RM) walls to prevent the vertical steel bars from buckling. In the current version of the Australian Masonry Standards (AS 3700–2018), the use of lateral restrainers in RM walls is relaxed, if the vertical rebars are surrounded by grout annulus of twice the diameter of the bars. However, it is challenging to maintain the verticality of the reinforcing bars in the block cores to satisfy the grout annulus requirement without lateral restrainers. To address this challenge, restrainer bar chairs can be used in the construction of RM walls which are easier to employ in comparison to lateral restrainer ties. However, the implications of adopting restrainer bar chairs as an alternative to restrainer ties in RM wall construction are not well verified. In this study, the influence of restrainer bar chairs and conventional lateral ties restraining methods on the axial compression and out-of-plane bending characteristics of RM walls have been investigated. In total, twelve RM walls of dimensions 1390 mm height × 590 mm length × 190 mm thickness were constructed and tested, of which, four walls each were tested under concentric and eccentric compression and four-point bending. The experimental results revealed that the performance of RM walls with restrainer bar chairs and conventional lateral ties were similar, in terms of the observed failure modes, strength, load–displacement characteristics obtained under both compression and out-of-plane loading conditions. Strain measurements on rebars indicated that a composite action was ensued in both restrainer configurations. The capacities of the RM walls under compression and out-of-plane bending were also verified with three different masonry standards provisions and were found adequate with reasonable safety. Overall, it can be concluded that the restrainer bar chairs can effectively be used in RM walls to enable quick and accurate vertical positioning of the rebars and ensure adequate grout annulus around them.

The desiccant wheel based air conditioning systems are superior over conventional vapour compression systems in terms of the efficiency and power consumption. Researchers are consistently focusing on the various aspects of the desiccant wheel such as the architecture of the wheel, effect of operating parameters on the performance of the wheel and the overall configuration of air-conditioning systems. For the simulations of the air-conditioning systems it is essential to have an accurately performing model of the desiccant wheel. Thus, for solving this purpose, the radial basis neural network is applied to forecast the performance of a desiccant wheel data. The input parameters are the inlet process air humidity, temperature, regeneration temperature, number of rotations per hour of the desiccant wheel and the ratio of the volume flow rates of the process air and the regeneration air. The output parameters are the temperature and humidity of the process air outlet stream. The model is able to predict the original data within ± 5% accuracy and the r-square value is obtained to be 0.9963. A parametric study presenting the variations of the process air outlet temperature and humidity with respect to the various input parameters is also included in the article.

OBJECTIVE S2 alar-iliac (S2AI) screw fixation effectively enhances stability in long-segment constructs. Although S2AI fixation provides a single transarticular sacroiliac joint fixation (SIJF) point, additional fixation points may provide greater stability and attenuate screw and rod strain. The objectives of this study were to evaluate changes in stability and pedicle screw and rod strain with extended distal S2AI fixation and with supplemental bilateral integration of two sacroiliac joint fusion devices implanted using a traditional minimally invasive surgical approach. METHODS Eight L1–pelvis human cadaveric specimens underwent pure moment (7.5 Nm) and compression (400 N) tests under 4 conditions: 1) intact (pure moment loading only); 2) L2–S1 pedicle screw and rod with L5–S1 interbody fusion; 3) added S2AI screws; and 4) added bilateral laterally placed SIJF. Range of motion (ROM), rod strain, and screw-bending moment (S1 and S2AI) were analyzed. RESULTS Compared with S1 fixation, S2AI fixation significantly reduced L5–S1 ROM in right lateral bending by 50% (0.11°, p = 0.049) and in compression by 39% (0.22°, p = 0.003). Compared with fixation ending at S1, extending fixation with S2AI significantly decreased sacroiliac joint ROM by 52% (0.28°, p = 0.02) in flexion, by 65% (0.48°, p = 0.04) in extension, by 59% (0.76°, p = 0.02) in combined flexion-extension, and by 36% (0.09°, p = 0.02) in left axial rotation. The addition of S2AI screws reduced S1 screw-bending moment during flexion (0.106 Nm [43%], p = 0.046). With S2AI fixation, posterior L5–S1 primary rod strain increased by 124% (159 μE, p = 0.002) in flexion, by 149% (285 μE, p = 0.02) in left axial rotation, and by 99% (254 μE, p = 0.04) in right axial rotation. Compared with S2AI fixation, the addition of SIJF reduced L5–S1 strain during right axial rotation by 6% (28 μE, p = 0.04) and increased L5–S1 strain in extension by 6% (28 μE, p = 0.02). CONCLUSIONS Long-segment constructs ending with S2AI screws created a more stable construct than those ending with S1 screws, reducing lumbosacral and sacroiliac joint motion and S1 screw-bending moment in flexion. These benefits, however, were paired with increased rod strain at the lumbosacral junction. The addition of SIJF to constructs ending at S2AI did not significantly change SI joint ROM or S1 screw bending and reduced S2AI screw bending in compression. SIJF further decreased L5–S1 rod strain in axial rotation and increased it in extension.

The short-term vibration response of uncracked prestressed concrete (PC) members under long-age conditions was investigated. No study has examined long-term phenomena of concrete, such as its tendon relaxation, creep, curing, and shrinkage, under the aforementioned conditions. Therefore, a research sub-program was initiated at the National Center for Research on Earthquake Engineering on the basis of an experimental campaign on uncracked PC bridge members initiated in 2015. In particular, a simply supported PC beam composed of a parabolic-bonded tendon and high-strength concrete made in Taiwan was allowed to short and, consequently, long-term prestressing losses measured for approximately 9.5 months. During short-term prestressing losses and after long-term prestressing losses, free short-term transverse vibrations were induced in the PC beam characterized by a second-order initial curvature and an axial end constraint. The time-dependent Young’s modulus of the beam was determined by conducting compression tests on cylinders during the short-term prestressing losses. Moreover, compression tests were conducted on cores drilled along the PC beam’s span after free vibration tests. The theoretical time-dependent Young’s modulus of the beam was evaluated according to the compression test results. The experimental data were compared with a reference Euler–Bernoulli solution and finite-element (FE) model that describe the dynamics of PC girders by considering the effective prestressing force. The fundamental frequencies of the PC beam were mainly sensitive to the variation in its initial tangent Young’s modulus due to the consolidation or hardening of concrete. These frequencies were unaffected by the second-order initial curvature. In conclusion, the reference solution and FE model can accurately predict the short-term dynamics of uncracked PC members exposed for long times.

Primarily, columns carry axial loads, and therefore, these are designed for compression. Other loads from snow, wind, or earthquake forces can cause bending in the columns. Columns then need to be developed for Axial Load and Bending. The cost-effective design of columns is the biggest problem when we are going to design a building. The optimal design of a building depends on the costs of all three reinforced concrete elements: beam, column, and slabs. These all should also be designed with optimal. This research work aims to find the minimum cost of RCC column subjected to two types of loadings i,e axial loading and uniaxial moments. The objective of this research work was to reduce the total price of RCC column after applying all the design guidelines according to BIS codes 456:2000 (without ductile detailing) and 13920;1993 (with ductile detailing). Generally, we cannot mark a structure with a minimum cost but it should also design according to the Indian standard codes. The cost comparison of RCC column results, taken according to BIS codes, has been carried out to check the differences in the price of both cases. We found that in the case of 4 m column length, the axial load, moment, and grade of steel values are 1200kN, 200kNm, and 500 N/mm2 respectively. The variation in cost is 11%-12% for all the phases of concrete. We also found that reinforcement detailing cost variation in 9 m and 12 m column lengths is significantly less. The cost percentage of optimal cost of RCC column is reduced when force and moment are increased. The Genetic Algorithm and Matlab software has been used in this research work.

Biomimicry can be termed as the concept that involves the imitation of models, systems and elements of the nature to solve complex human problems. When compared to the conventional techniques, it is an efficient, innovative and sustainable way and thus has scope in future. The various levels in biomimicry are utilized in the construction of the structures inspired from the nature thus paving way to innovation and sustainability. Various information can be learnt from nature when it comes to solving our challenges in a sustainable way. Nature builds to shape, because shape is cost effective and it minimizes the expenditure on materials while maximizing the effectiveness to achieve the desired functions. In this study the analysis of the conventional pin jointed plane frame is done first using STAAD. Pro to identify the compression and tension members in the frame. The various conventional frame models are modelled and analyzed. The finite element analysis is done using ANSYS 2020R2. A conventional pin jointed plane frame of height 4 m, bay width 4 m and strut length of 5.66 m were analyzed to know its member properties. A conventional pin jointed frame with horizontal springs provided at both the sides of the frame was modelled and analyzed. The optimized mimicked members are assembled to form the mimicked frame and analyzed. The various parameters such as total deformation, directional deformation, normal stress, equivalent stress, maximum principal stress and minimum principal stress were compared for the pin jointed plane frames. The present study helps in the reduction of material usage and self-weight of elements thus resulting in a sustainable and efficient structure

Chronic physeal stress injuries in children can result from ongoing, repetitive compression, distraction and/or shear forces during sports-related activity, and manifest as physeal widening on imaging. We present an 11-year-old soccer athlete with focal physeal widening of her great toe metatarsal and postulate that ongoing or repetitive stress from soccer play may manifest as this imaging appearance. We suggest that recognition of this entity in growing children might explain pain, if present, and guide conservative treatment.

Desmoid tumor, also known as desmoid-type fibromatosis, is a rare, intermediate, locally aggressive tumor with a high possibility of local infiltration and recurrence, potentially leading to life-threatening problems. We report a case of a 15-year-old girl who visited the emergency department with a 1-week history of the left leg swelling. A point-of-care ultrasound on the leg showed dilated left femoral and popliteal veins. Subsequently, a computed tomography venogram demonstrated a large pelvic mass compressing the left external iliac vein. She underwent tumor resection, and was uneventfully discharged on day 12.

Background Recent studies have indicated that injuries such as muscle tears modify the microstructural integrity of muscle, leading to substantial alterations in measured diffusion parameters. Therefore, the fractional anisotropy (FA) value decreases. However, we hypothesized that soft tissue, such as muscle tissue, undergoes reversible changes under conditions of compression without fiber injury. Purpose To evaluate the FA change due to compression in muscle tissue without fiber injury. Material and Methods Diffusion tensor imaging (DTI) was performed on both feet of 10 healthy volunteers (mean age = 35.0 ± 10.39 years; age range = 23–52 years) using a 3.0-T magnetic resonance imaging (MRI) scanner with an eight-channel phased array knee coil. An MRI-compatible sphygmomanometer was applied to the individuals’ lower legs and individuals were placed in a compressed state. Then, rest intervals of 5 min were set in re-rest state after compression. The FA value, apparent diffusion coefficient (ADC), and eigenvalues (λ1, λ2, λ3) of the gastrocnemius and soleus muscle were measured at each state. Results The mean FA values increased in all muscles in a compressed state, while the mean λ3 decreased. In all muscles, significant differences were found between the rest and compressed states in terms of mean FA and λ3 ( P Conclusion We confirmed the reversibility of the DTI metrics, which suggests that there was no muscle injury during this study. In cases of compression without fiber injury, the FA value increases, because fibers are strongly aligned in the longitudinal direction.

The use of Ultra-High Performance Concrete (UHPC) has been growing rapidly in the past two decades because of its superior mechanical and durability properties compared to conventional concrete (CC). Flexural strength prediction models of CC components underestimate the flexural strength of non-prestressed UHPC components as they ignore the tensile strength of concrete and assume different stress–strain relationships and failure mode from those of UHPC. The objective of this paper is to evaluate the current flexural strength prediction models of non-prestressed UHPC components using test data collected from the literature and validate them using experimental data of a UHPC ribbed slab tested in flexure. Measured and predicted flexural strengths are compared at different curvatures. Evaluation results indicated that neglecting the tensile strength of UHPC significantly underestimates the flexural strength of non-prestressed UHPC components. Peak moment curvature of non-prestressed UHPC components is significantly smaller than ultimate moment curvature. In addition, the differences among idealized stress–strain relationships of UHPC in compression and tension do not have significant effect on the predicted flexural strength.

In this article, we studied the instability phenomenon of plate buckling made of steel (E36-S355), and magnetorheological elastomer subject to compression loading. The study of the magnetic field intensity influence on the buckling instability of compressed hybrid plates is done by a mathematical development using the Ritz approach and by a numerical simulation under the Abaqus software. The obtained results show clearly that we can control the instabilities of the adaptive smart plate’s behavior by the magnetic field, and the orientation angle of pseudo-fibers formed by the iron particles; depending on the variation of the angle direction of the magnetic field.

The stress–strain characteristics of reinforced masonry (RM) under axial compression should be correctly understood to effectively analyse and design RM elements. However, past studies have overlooked this aspect and mainly focused on assessing the stress–strain behaviour of grouted or confined masonry. An experimental programme was executed in this research by constructing and testing RM wallettes under uniaxial compression to understand the stress–strain behaviour of RM. The effects of grout strength and lateral restrainer configurations on the compression behaviour were also studied. The experimental outcome revealed that the grout plays a major role in the axial capacity of the RM, while change in the configurations of the lateral restraining reinforcement did not significantly affect the axial capacities and axial stress–strain behaviour of RM wallettes. The predictability of the axial capacity of the RM wallettes were validated through the expressions given in the three masonry design standards. It was observed that all considered standards conservatively predicted the axial capacity of the RM. Moreover, the applicability of the existing analytical models in the literature for the RM were verified against the experimental data and an improved stress–strain model is proposed in this research.

Background Several serious complications are associated with the lithotomy position, including well-leg compartment syndrome and peroneal nerve paralysis. The aims of this study were to identify risk factors for the intraoperative elevation of lower leg pressure and to evaluate the effectiveness of monitoring external pressure during surgery for preventing these complications. Methods The study included 106 patients with a diagnosis of sigmoid colon or rectal cancer who underwent elective laparoscopic surgery between June 2019 and December 2020. We divided the posterior side of the lower leg into four parts (upper outside, upper inside, lower outside, lower inside) and recorded the peak pressure applied to each area at hourly intervals during surgery (called "regular points") and when the operating position was changed (e.g., by head-tilt or leg elevation; called "points after change in position"). When the pressure was observed to be higher than 50 mmHg, we adjusted the position of the leg and re-recorded the data. Data on postoperative leg-associated complications were also collected. Results The pressure was measured at a total of 1125 points (regular, n = 620; after change of position, n = 505). The external pressure on the upper outer side of the right leg (median, 36 mmHg) was higher than that on any other area of the lower leg. The pressure increase to more than 50 mmHg was observed not only during the change of position (27.5%) but also during regular points (22.4%). Bodyweight, strong leg elevation, and low head position were identified as factors associated with increased external pressure. There have been no compression-related complications in 534 cases at our institution since the introduction of intraoperative pressure monitoring. Conclusions Several risk factors associated with increased external pressure on the lower leg were identified. Intraoperative pressure monitoring might help reduction of pressure-related complications, needing further and larger prospective data collections.

Knowledge of the normal size of important abdominal vessels is important for determination of hydration status and intravascular volume. Knowing the normal value of superior mesenteric artery (SMA) exit angle from the aorta (SMA angle) is necessary for the diagnosis of clinical pathologies caused by SMA compression.The aim of this study was to determine the normal SMA angles and normal diameters of the main abdominal vascular structures of pediatric participants on ultrasonography (USG).Between January 2019 and July March 2019, the USG examinations obtained from 210 participants (age range, 1-214 years; mean age, 83.5 [SD, 5.5] months; females 51%, males 49%) with normal abdominal examinations were prospectively evaluated. The participants were divided into 5 groups according to age. Body mass index values of the participants were kept equal.The diameters of the abdominal vascular structures increased with age, and the statistical differences among the age groups were significant. In all groups, no statistically significant difference was observed between sexes (P0.05). The SMA angle was between 17° and 58° (mean, 37.8° [SD, 8.5°]). A statistically significant difference was observed between the age groups in terms of SMA angle (P0.05). No statistically difference was found between sexes (P0.58-0.912).In our study, we think that the measurements obtained by USG provide normal values of the diameters of the abdominal main vessels and SMA angle. These values can be used as a reference for interpreting hydration status, vascular diameter assessment, and SMA compression syndromes.

In the 1960’s, concrete structures subjected to plane stresses started being idealized as a combination of two-dimensional components called membrane elements. After several research groups having collected experimental data from reinforced concrete panels, material’s constitutive models were improved to better describe shear behavior. The Modified Compression Field Theory (MCFT) was developed by University of Toronto’s research team and made good predictions for a wide range of structures. Much later, the Disturbed Stress Field Model (DSFM) was born as an upgrade to the previous model, correcting some deficiencies found in specific situations. This paper contributes in this field by developing an open source Microsoft.NET library, named RCMembrane, for analysis of membrane elements by MCFT and DSFM. The results were validated by comparing numerical solution to the experimental data of 72 reinforced concrete panels. For Disturbed Stress Field Model (DSFM), a new relation is proposed for minimizing concrete’s compression softening effect in panels subjected to tensile stresses. In general, RCMembrane’s solution algorithm obtained very near load capacity prediction for those two distinct formulations, with a slightly smaller coefficient of variation in DSFM results. Next, RCMembrane must be applied to full finite element formulations, so further conclusions can be taken from numerical simulations of usual reinforced concrete structures.

Objective To evaluate the the clinical efficacy of the preoperative digital design combined with three-dimensional (3D) printing models to assist percutaneous kyphoplasty (PKP) treatment for thoracolumbar compression fractures. Methods From January 2018 to August 2020, we obtained data of 99 patients diagnosed thoracolumbar compression fractures. These patients were divided into control group (n = 50) underwent traditional PKP surgery, and observation group (n = 49) underwent preoperative digital design combined with 3D printing model assisted PKP treatment. The clinical efficacy was evaluated with five parameters, including operation time, number of intraoperative radiographs, visual analogue scale (VAS) score, Cobb Angle change, and high compression rate of injured vertebrae. Results There were statistically significant differences of operation time and number of intraoperative radiographs between the two groups (P 0.05). Conclusions Through the design of preoperative surgical guide plate and the application of 3D printing model to guide the operation, the precise design of preoperative surgical puncture site and puncture Angle of the injured vertebra was realized, the number of intraoperative radiographs was reduced, the operation time was shortened and the operation efficiency was improved.

Ultra high performance fiber reinforced concrete (UHPFRC) is a promising new concrete, especially in repair and restoration. It has been identified to exhibit good bonding and strengthening properties with the old concrete as an overlay repair material. But its usage has not been much pronounced due to its high-cost factor which overshadows its efficacy, because certain constituents of UHPFRC are not readily and easily available. Hence, optimal usage of this concrete for repair and rehabilitation can greatly be beneficial to the construction industry. Therefore, this study is involved in identifying the optimum thickness of UHPFRC as a repair overlay material for normal concrete elements, so that the self-weight of the material can be reduced to its minimum, and indirectly the impact of its price can be greatly reduced. With this intention, normal concrete elements were repaired with different thicknesses of UHPFRC overlay starting from 15 mm to 50 mm. The repaired composite composed of normal concrete substrate and varying thickness of UHPFRC overlay were subjected to different property evaluations to identify the optimum thickness of UHPFRC overlay in compression, tension, and shear. The ideal thickness of the UHPFRC repair overlay was concluded based on its ability to restore the original strength of the old normal concrete. It was upshot that an overlay thickness of 20 mm is more than sufficient to repair and restore the normal concrete.

For typical aerospace alloys, the mechanical properties of TC4 titanium alloy and 7075 aluminum alloy at different loading rates were investigated by uniaxial tension and compression experiments. The fracture microscopic morphologies of the two alloys were compared and analyzed using a scanning electron microscope. In addition, the experiment also combined infrared thermography technology (IRT) to compare and analyze the temperature variation characteristics of TC4 titanium alloy specimens under the same tensile and compressive loading rates. The research results show that the mechanical properties of TC4 titanium alloys are superior to those of 7075 aluminum alloys under the same tensile and compressive loading rates. Constitutive equations considering power-law hardening and tensile loading rate were derived to express the yield flow stress behavior.

The relationship between internal loading dose and low-back injury risk during lifting is well known. However, the implications of movement parameters that influence joint loading rates—movement frequency and speed—on time-dependent spine loading responses remain less documented. This study quantified the effect of loading rate and frequency on the tolerated cumulative loading dose and its relation to joint lifespan. Thirty-two porcine spinal units were exposed to biofidelic compression loading paradigms that differed by joint compression rate (4.2 and 8.3 kN/s) and frequency (30 and 60 cycles per minute). Cyclic compression testing was applied until failure was detected or 10,800 continuous cycles were tolerated. Instantaneous weighting factors were calculated to evaluate the cumulative load and Kaplan–Meier survival probability functions were examined following nonlinear dose normalization of the cyclic lifespan. Significant reductions in cumulative compression were tolerated when spinal units were compressed at 8.3 kN/s (P P = .008, 45%). There was a positive moderate relationship between cumulative load tolerance and normalized cyclic lifespan (R2 = .52), which was supported by joint survivorship functions. The frequency and speed of movement execution should be evaluated in parallel to loading dose for the management of low-back training exposures.

This paper presents an experimental and numerical investigation into the stability of normal and high strength steel circular hollow section (CHS) columns. Two cold-formed S700 CHS profiles – 139.7×4 and 139.7×5 (in mm), were studied in the experimental programme, and twelve column tests (six on each profile), together with accompanying material tests, were performed. The load-deformation histories and key results from the tests are reported. Following the physical testing, a numerical simulation campaign was conducted. The developed finite element (FE) models for CHS columns were initially validated against the test results. Parametric studies were then carried out, where 2000 additional buckling resistance data were numerically generated for hot-finished and cold-formed CHS columns, covering steel grades from S355 to S900. The obtained test and FE results, together with existing experimental data from the literature, were used to assess the current Eurocode 3 stability design rules. It was shown that the normalised performance of CHS columns is influenced by the yield strength, which is not fully captured by the EC3 design approach. The somewhat conservative Class 3 slenderness limit for compression further worsen the accuracy for those with slender cross-sections. Improvements to the EC3 design rules were proposed to address these shortcomings, including (a) modified Ayrton-Perry formulae enabling a continuous transition of buckling curves across the yield strength spectrum and (b) a new Class 3 limit for CHS in compression. The modified EC3 approach was assessed and shown to improve the accuracy and consistency of resistance predictions over the current EC3 approach, while meeting the Eurocode structural reliability requirements.

Strong laminar/transitional shock boundary layer interactions (SBLIs) have been investigated in a Mach 4 vacuum-driven wind tunnel with supporting computational fluid dynamics analysis. Such flows ...

Concrete-filled steel tubular (CFST) column may be undergone coupled compression and torsion during its service life, and therefore, six CFST specimens were tested to analyze the torsional behaviour. The failure modes, torsion moment (T) versus torsional angle (θ) relationships and torsion moment-strain curves derived from the testing results for CFST specimens under different torsion conditions were compared and analyzed. Meanwhile, the numerical model of CFST members was developed via the software ABAQUS to further analyze the torsional mechanism. Moreover, the comparison of torsional performance between CFST column and steel-reinforced concrete-filled steel tubular (SRCFST) column was conducted. The results indicated that the T-θ curve of each specimen showed slight difference in the initial stage under diverse loading conditions; however, the specimens under torsion after compression exhibited highest ultimate torsional capacity, followed by the specimens under simultaneous compression-torsion and pure torsion. The T-θ curve of SRCFST columns with I-section steel or cruciform steel was similar to that of CFST columns, but the T-θ curve of SRCFST columns increased obviously in the later stage due to the inserted steel tube. In addition, the validity of the numerical model was verified against experiment. Then, the interaction force between steel tube and concrete and the internal forces of the characteristic points of the T-θ curves under different loading conditions and axial load levels were compared to understand the stress mechanism. Finally, the proposed calculation method for torsional capacity of CFST members under coupled compression-torsion could provide a more accurate prediction.

The accuracy of different fire design methodologies for hollow cross-sections subject to compression and major-axis bending is studied and compared in this paper. For that purpose, a numerical model based on shell finite elements is developed and validated against existing experimental results available in the literature. Comprehensive numerical parametric studies are then carried out by means of the validated numerical model, including different cross-section dimensions, loading conditions, steel grades and temperatures, to obtain a large set of results of the ultimate resistance of hollow sections in fire. Based on these results, the existing design rules of the Eurocode 3 Part 1–2, the AISC 360 specification and the recent design proposals of Couto et al. [1,2] and the Direct Strength Method adapted to fire are assessed in terms of their accuracy for predicting the section capacity, including the resistance against local buckling at elevated temperatures. It is demonstrated that the cross-sectional classification procedure for the case of fire, available in the Eurocode 3 and AISC specifications, results in inconsistencies and should be further investigated and revised in the future. To overcome the Eurocode 3 limitations it is proposed that the design methodology of Couto et al. [1,2] is adopted irrespective of the cross-section classification and for the AISC specification it is suggested the use of a reduced stress based on the 0.2% proof strength until more efficient design methods are developed.

Sternal approximation post-cardiac surgery in neonates can sometimes be challenging. Neonatal truncus arteriosus repair using a right ventricle to pulmonary artery homograft conduit is one such surgical procedure wherein there is a risk of developing conduit compression after sternal closure. We describe our technique of pericardio-phrenic release at the time of delayed sternal closure to prevent hemodynamic compromise and conduit compression after sternal approximation in such cases.

Biomechanical characteristics of artificial spinal fusion device plays an important role in the spinal joint replacement surgery. In this work, the analysis methods of biomechanical characteristics of spinal fusion device were studied. Based on finite element method, the elastoplastic compression process of spinal fusion device was simulated, and the key biomechanical characteristics parameters of fusion device were calculated. Finally, the fatigue life simulation of the device was carried out, and the rationality of the simulation method was verified by the elastoplastic compression experiment and fatigue life test. The research was of great significance for the optimal design of spinal fusion device, especially in improving the safety of the device.

Purpose The aim of this work was to investigate the risk factors for cement leakage and new-onset OVCF after Percutaneous vertebroplasty (PVP) and to develop and validate a clinical prediction model (Nomogram). Methods Patients with Osteoporotic VCF (OVCF) treated with PVP at Liuzhou People’s Hospital from June 2016 to June 2018 were reviewed and met the inclusion criteria. Relevant data affecting bone cement leakage and new onset of OVCF were collected. Predictors were screened using univariate and multi-factor logistic analysis to construct Nomogram and web calculators. The consistency of the prediction models was assessed using calibration plots, and their predictive power was assessed by tenfold cross-validation. Clinical value was assessed using Decision curve analysis (DCA) and clinical impact plots. Results Higher BMI was associated with lower bone mineral density (BMD). Higher BMI, lower BMD, multiple vertebral fractures, no previous anti-osteoporosis treatment, and steroid use were independent risk factors for new vertebral fractures. Cement injection volume, time to surgery, and multiple vertebral fractures were risk factors for cement leakage after PVP. The development and validation of the Nomogram also demonstrated the predictive ability and clinical value of the model. Conclusions The established Nomogram and web calculator (https://dr-lee.shinyapps.io/RefractureApp/) (https://dr-lee.shinyapps.io/LeakageApp/) can effectively predict the occurrence of cement leakage and new OVCF after PVP.

In the effort to mitigate the depletion of fossil fuels and climate change, biodiesels are considered to be one of the most suitable substitutes for petro-diesel in compression ignition engine appl...

Objective: In cardiac arrest cases, high quality cardiopulmonary resuscitation and effective chest compression are vital issues in improving survival with good neurological outcomes. In this study, we investigated the effect of mechanical chest compression devices on 30- day survival in out-of-hospital cardiac arrest. Materials and Methods: This retrospective case-control study was performed on patients who were over 18 years of age and admitted to the emergency department for cardiac arrest between January 1, 2016 and January 15, 2018. Manual chest compression was performed to the patients before January 15, 2017, and mechanical chest compression was performed after this date. Return of spontaneous circulation, hospital discharge, and 30-day survival rates were compared between the groups of patients in terms of chest compression type. In this study, the LUCAS-2 model piston-based mechanical chest compression device was used for mechanical chest compressions. Results: The rate of return of spontaneous circulation was significantly lower in the mechanical chest compression group (11.1% vs 33.1%; p < 0.001). The 30-day survival rate was higher in the manual chest compression group (6.8% vs 3.7%); however, this difference was not statistically significant (p = 0.542). Furthermore, 30-day survival was 0% in the trauma group and 0.6% in the patient group who underwent cardiopulmonary resuscitation for over 20 minutes. Conclusion: It can be seen that the effect of mechanical chest compression on survival is controversial; studies on this issue should continue and, furthermore, studies on the contribution of mechanical chest compression on labor loss should be conducted.