Effect of true triaxial principal stress unloading rate on strain energy density of sandstone.

Deep rock are often in a true triaxial stress state. Studying the impacts of varying unloading speeds on their strain energy (SE) density is highly significant for predicting rock stability. Through true triaxial unloading principal stress experiments and true triaxial stress equilibrium unloading experiments on sandstone, this paper proposes a method to compute the SE density in a true triaxial compressive unloading principal stress test. This method aims to analyze the SE variation in rocks under the action of true triaxial unloading principal stresses. Acoustic emission is used to verify the correctness of the SE density calculation method in this paper. This study found that: (1) Unloading in one principal stress direction causes the SE density to rise in the other principal stress directions. This rise in SE, depending on its reversibility, can be categorized into elastic and dissipated SE. (2)When unloading principal stresses, the released elastic SE density in the unloading direction is influence by the stress path and rate. (3) The higher the unloading speed will leads to greater increases in the input SE density, elastic SE density, and dissipative SE density in the other principal stress directions. (4) The dissipated SE generated under true triaxial compression by unloading the principal stress is positively correlated with the damage to the rock; with an increase in unloading rate, there is a corresponding increase in the formation of cracks after unloading. (5) Utilizing the stress balance unloading test, we propose a calculation method for SE density in true triaxial unloading principal stress tests.

Analysis of size effect and its influencing factors of brittle red sandstone with different heights.

We carried out uniaxial compression tests on brittle red sandstone with different heights. The test results show that the uniaxial compressive strength of rock sample increases first and then tends to be stable with the increase of the size, which is approximately stable between 75 and 81 MPa. Both elastic energy and dissipated energy increase with the increase of rock sample size. In order to further analyze the mechanism behind these phenomena, we combined advanced numerical simulation and theoretical analysis to explain these phenomena, and systematically analyzed the end face effect as one of the key factors affecting the uniaxial compression characteristics of brittle red sandstone for the first time. Small sized rock samples are very sensitive to end effect. The middle of the large sized rock samples is in a uniform compression state, and the effect of end effect is weakend. When there are rigid pads at both ends of the rock sample, there is an obvious elastic vertebral body during the loading process of the rock sample. The bearing capacity of rock samples with rigid pads is greater than that of rock samples without rigid pads, and the energy released during instantaneous failure of rock samples without rigid pads is greater than that of rock samples with rigid pads. The findings of this paper make a valuable contribution to establishing optimal study sample sizes and advancing the utilization of laboratory test mechanics parameters in engineering applications.

Magnetic compression anastomosis to restore biliary tract continuity after obstruction following major abdominal trauma: A case report.

BACKGROUND: The combination of magnetic compression anastomosis (MCA) and endoscopy has been used to treat biliary stricture after liver transplantation. However, its use for the treatment of complex biliary obstruction after major abdominal trauma has not been reported. This case report describes the successful use of MCA for the treatment of biliary obstruction resulting from major abdominal trauma. CASE SUMMARY: A 23-year-old man underwent major abdominal surgery (repair of liver rupture, right half colon resection, and ileostomy) following a car accident one year ago. The abdominal drainage tube, positioned at the Winslow foramen, was draining approximately 600-800 mL of bile per day. During the two endoscopic retrograde cholangiopancreatography procedures, the guide wire was unable to enter the common bile duct, which prevented placement of a biliary stent. MCA combined with endoscopy was used to successfully achieve magnetic anastomosis of the peritoneal sinus tract and duodenum, and then a choledochoduodenal stent was placed. Finally, the external biliary drainage tube was removed. The patient achieved internal biliary drainage leading to the removal of the external biliary drainage tube, which improved the quality of life. CONCLUSION: Magnetic compression technique can be used for the treatment of complex biliary obstruction with minimal operative trauma.

Novel magnetic compression technique for the treatment of postoperative anastomotic stenosis in rectal cancer: A case report.

BACKGROUND: The treatment of postoperative anastomotic stenosis after excision of rectal cancer is challenging. Endoscopic balloon dilation and radial incision are not effective in all patients. We present a new endoscopy-assisted magnetic compression technique (MCT) for the treatment of rectal anastomotic stenosis. We successfully applied this MCT to a patient who developed an anastomotic stricture after radical resection of rectal cancer. CASE SUMMARY: A 50-year-old man had undergone laparoscopic radical rectal cancer surgery at a local hospital 5 months ago. A colonoscopy performed 2 months ago indicated that the rectal anastomosis was narrow due to which ileostomy closure could not be performed. The patient came to the Magnetic Surgery Clinic of the First Affiliated Hospital of Xi'an Jiaotong University after learning that we had successfully treated patients with colorectal stenosis using MCT. We performed endoscopy-assisted magnetic compression surgery for rectal stenosis. The magnets were removed 16 d later. A follow-up colonoscopy performed after 4 months showed good anastomotic patency, following which, ileostomy closure surgery was performed. CONCLUSION: MCT is a simple, non-invasive technique for the treatment of anastomotic stricture after radical resection of rectal cancer. The technique can be widely used in clinical settings.

Laparoscopic Treatment of a Symptomatic Young Woman With Median Arcuate Ligament Syndrome.

Median arcuate ligament syndrome (MALS), also known as Dunbar syndrome, celiac axis syndrome, or celiac artery compression syndrome, is caused by a band of tissue called the median arcuate ligament that compresses the celiac artery and sometimes the celiac plexus too. MALS does not always cause symptoms, but when symptoms occur, surgery is the treatment of choice. This case report focuses on the case of a 27-year-old woman presenting with postprandial episodes of abdominal pain and vomiting accompanied by loss of weight, which was found to be MALS.

A multi-centre retrospective study of long-term outcomes of spinal re-irradiation with SABR.

INTRODUCTION: Stereotactic ablative body radiotherapy (SABR) is a highly conformal technique utilising a high dose per fraction commonly employed in the re-treatment of spinal metastases. This study sought to determine the safety and efficacy of re-irradiation with SABR to previously treated spinal metastases. METHODS: This was a retrospective analysis of patients at three Australian centres who have undergone spinal SABR after previous spinal radiotherapy to the same or immediately adjacent vertebral level. Efficacy was determined in terms of rates of local control, while safety was characterised by rates of serious complications. RESULTS: Thirty-three spinal segments were evaluated from 32 patients. Median follow-up for all patients was 2.6 years, and median overall survival was 4.3 years. Eleven of 33 (33.3%) treated spinal segments had local progression, with a local control rate at 12 months of 71.4% (95% C.I. 55.2%-92.4%). Four patients (16.7%) went on to develop cauda equina or spinal cord compression. Thirteen out of 32 patients (40.6%) experienced acute toxicity, of which 12 were grade 2 or less. Five out of 30 spinal (16.7%) segments with follow-up imaging had a radiation-induced vertebral compression fracture. There was one case of radiation myelitis which occurred in a patient who had mediastinal radiotherapy with a treatment field which overlapped their prior spinal radiation. CONCLUSION: The patients in this study experienced long median survival, durable tumour control and high rates of freedom from long-term sequelae of treatment. These results support the use of SABR in patients who progress in the spine despite previous radiotherapy.

Pushing Pressure Detection Sensitivity to New Limits by Modulus-Tunable Mechanism.

Only microstructures are used to improve the sensitivity of iontronic pressure sensors. By modulating the compressive modulus, a breakthrough in the sensitivity of the iontronic pressure sensor is achieved. Furthermore, it allows for programmatic tailoring of sensor performance according to the requirements of different applications. Such a new strategy pushes the sensitivity up to a record-high of 25 548.24 kPa-1 and expands the linear pressure range from 15 to 127 kPa. Additionally, the sensor demonstrates excellent mechanical stability over 10 000 compression-release cycles. Based on this, a well-controlled robotic hand that precisely tracks the pressure behavior inside a balloon to autonomously regulate the gripping angle is developed. This paves the way for the application of iontronic pressure sensors in precise sensing scenarios.

Computational comparison study of virtual compression and shear test for estimation of apparent elastic moduli under various boundary conditions.

Virtual compression tests based on finite element analysis are representative noninvasive methods to evaluate bone strength. However, owing to the characteristic porous structure of bones, the material obtained from micro-computed tomography images in the finite-element model is not uniformly distributed. These characteristics cause differences in the apparent elastic moduli depending on the boundary conditions and affect the accuracy of bone-strength evaluation. Therefore, this study aimed to evaluate and compare the apparent elastic moduli under various, virtual-compression and shear-test boundary conditions. Four, nonuniform models were constructed with increasing model complexity. For representative boundary conditions, two, different, testing directions, and constrained surfaces were applied. As a result, the apparent elastic moduli of the nonuniform model varied up to 55.2% based on where the constrained surface was located in the single-end-cemented condition. Additionally, when connectivity in the test direction was lost, the accuracy of the apparent elastic moduli was low. A graphical comparison showed that the equivalent-stress distribution was more advantageous for analyzing load transferability and physical behavior than the strain-energy distribution. These results clearly show that the prediction accuracy of the apparent elastic moduli can be guaranteed if the boundary condition on the constraint and loading surfaces of the nonuniform model are applied symmetrically and the connectivity of the elements in the testing direction is well maintained. This study will aid in precision improvement of bone-strength-indicator determination for osteoporosis prevention.

Pectus excavatum: the effect of tricuspid valve compression on cardiac function.

BACKGROUND: Pectus excavatum (PE) is a common congenital chest wall deformity with various associated health concerns, including psychosocial impacts, academic challenges, and potential cardiopulmonary effects. OBJECTIVE: This study aimed to investigate the cardiac consequences of right atrioventricular groove compression in PE using cardiac magnetic resonance imaging. MATERIALS AND METHODS: A retrospective analysis was conducted on 661 patients with PE referred for evaluation. Patients were categorized into three groups based on the degree of right atrioventricular groove compression (no compression (NC), partial compression (PC), and complete compression(CC)). Chest wall indices were measured: pectus index (PI), depression index (DI), correction index (CI), and sternal torsion. RESULTS: The study revealed significant differences in chest wall indices between the groups: PE, NC=4.15 ± 0.94, PC=4.93 ± 1.24, and CC=7.2 ± 4.01 (P<0.0001). Left ventricle ejection fraction (LVEF) showed no significant differences: LVEF, NC=58.72% ± 3.94, PC=58.49% ± 4.02, and CC=57.95% ± 3.92 (P=0.0984). Right ventricular ejection fraction (RVEF) demonstrated significant differences: RVEF, NC=55.2% ± 5.3, PC=53.8% ± 4.4, and CC=53.1% ± 4.8 (P≥0.0001). Notably, the tricuspid valve (TV) measurement on the four-chamber view decreased in patients with greater compression: NC=29.52 ± 4.6; PC=28.26 ± 4.8; and CC=24.74 ± 5.73 (P<0.0001). CONCLUSION: This study provides valuable insights into the cardiac consequences of right atrioventricular groove compression in PE and lends further evidence of mild cardiac changes due to PE.

Primary Creep Characterization in Porcine Lumbar Spine Subject to Repeated Loading.

Low back pain (LBP) is a common medical condition worldwide, though the etiology of injuries causing most LBP is unknown. Flexion and repeated compression increase lumbar injury risk, yet the complex viscoelastic behavior of the lumbar spine has not been characterized under this loading scheme. Characterizing the non-injurious primary creep behavior in the lumbar spine is necessary for understanding the biomechanical response preceding injury. Fifteen porcine lumbar spinal units were loaded in repeated flexion-compression with peak compressive stresses ranging from 1.41 to 4.68 MPa. Applied loading simulated real loading exposures experienced by high-speed watercraft occupants. The strain response in the primary creep region was modeled for all tests using a generalized Kelvin-Voigt model. A quasilinear viscoelastic (QLV) approach was used to separate time-dependent (creep) and stress-dependent (elastic) responses. Optimizations between the models and experimental data determined creep time constants, creep coefficients, and elastic constants associated with this tissue under repeated flexion-compression loading. Average R2 for all fifteen models was 0.997. Creep time constants optimized across all fifteen models were 24 s and 580 s and contributed to 20 ± 3% and 30 ± 3% of the overall strain response, respectively. The non-transient behavior contributed to 50 ± 0% of the overall response. Elastic behavior for this porcine population had an average standard deviation of 24.5% strain across the applied stress range. The presented primary creep characterization provides the response precursor to injurious behavior in the lumbar spine. Results from this study can further inform lumbar injury prediction and kinematic models.

Ultrasound-Based Multi-Planar Bilateral Comparisons as a Diagnostic and Treatment-Definition Method for Unilateral Peripheral Nerve Entrapment.

OBJECTIVE: The primary goal was to determine the performance of the cross-section area swelling rate (CSASR) for diagnostic and therapeutic purposes based on the reference standard of electrodiagnosis examination (EDX) in this diagnostic test study. METHODS: First, patients with symptoms like unilateral carpal tunnel syndrome (CTS), cubital tunnel syndrome (CuTS), and radial nerve compression (RNC) underwent EDX and ultrasound examination. Second, patients with positive ultrasound were calculated for the CSASR of diseased nerve. Based on previously established CSASR criteria, each patient was categorized as having or not having peripheral nerve entrapment, and for those meeting diagnostic criteria, non-surgical or surgical treatment was recommended. Then, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy rate (ACC) of ultrasound diagnosis and therapeutic decision-making were calculated based on the reference standard of EDX that had been historically used in the practice. RESULTS: The total sensitivity, specificity, PPV, NPV, and ACC of ultrasound diagnosis are respectively 93.4, 85.2, 94.7, 82.1, and 91.3%. Which of therapeutic decision-making by ultrasound are, respectively, 83.3, 52.2, 78.4, 60.0, and 73.2%. CONCLUSION: The sensitivity and Youden's index of CSASR diagnostic threshold for CuTS is higher than other ultrasound methods. The CSASR diagnostic threshold for CuTS has a potential diagnostic role, but the current date is still not enough to support the potential diagnostic role for CTS or RNS. There is insufficient evidence to suggest that CSASR for CuTS can be used in isolation for diagnosis. Additional research is needed to confirm the diagnostic role of CSASR. The current results suggest that this ultrasound examination method is not suitable for therapeutic decision-making.

Radiomics Based on Multimodal magnetic resonance imaging for the Differential Diagnosis of Benign and Malignant Vertebral Compression Fractures.

OBJECTIVES: Recent studies have indicated that radiomics may have excellent performance and clinical application prospects in the differential diagnosis of benign and malignant vertebral compression fractures (VCFs). However, multimodal magnetic resonance imaging (MRI)-based radiomics model is rarely used in the differential diagnosis of benign and malignant VCFs, and is limited to lumbar. Herein, this study intends to develop and validate MRI radiomics models for differential diagnoses of benign and malignant VCFs in patients. METHODS: This cross-sectional study involved 151 adult patients diagnosed with VCF in The First Affiliated Hospital of Soochow University in 2016-2021. The study was conducted in three steps: (i) the original MRI images were segmented, and the region of interest (ROI) was marked out; (ii) among the extracted features, those features with Pearson's correlation coefficient lower than 0.9 and the top 15 with the highest variance and Lasso regression coefficient less than and more than 0 were selected; (iii) MRI images and combined data were studied by logistic regression, decision tree, random forest and extreme gradient boosting (XGBoost) models in training set and the test set (ratio of 8:2), respectively; and the models were further verified and evaluated for the differential diagnosis performance. The evaluated indexes included area under receiver (AUC) of operating characteristic curve, accuracy, sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and 95% confidence intervals (CIs). The AUCs were used to assess the predictive performance of different machine learning modes for benign and malignant VCFs. RESULTS: A total of 1144 radiomics features, and 14 clinical features were extracted. Finally, 12 radiomics features were included in the radiomics model, and 12 radiomics features with 14 clinical features were included in the combined model. In the radiomics model, the differential diagnosis performance in the logistic regression model with the AUC of 0.905 ± 0.026, accuracy of 0.817 ± 0.057, sensitivity of 0.831 ± 0.065, and negative predictive value of 0.813 ± 0.042, was superior to the other three. In the combined model, XGBoost model had the superior differential diagnosis performance with specificity (0.979 ± 0.026) and positive predictive value (0.971 ± 0.035). CONCLUSION: The multimodal MRI-based radiomics model performed well in the differential diagnosis of benign and malignant VCFs, which may provide a tool for clinicians to differentially diagnose VCFs.

Guyon's canal syndrome resulting from an ulnar artery aneurysm: A case report.

INTRODUCTION AND IMPORTANCE: The ulnar's nerve compression at the Guyon's canal is not a frequent entity add to it that vascular lesions are rarely involved as a causative agent of this syndrome. CASE PRESENTATION: We report a case of a young male patient admitted in our department for a Guyon's canal syndrome due to an aneurysm of the ulnar artery and underwent a surgical decompression. Post-operative course was uneventful and the patient was satisfied with the result. CLINICAL DISCUSSION: Many etiologies are involved in the Guyon's canal syndrome and these etiologies can be arranged into groups. Previous treatment attempts, the duration and severity of the symptoms and the underlying etiology dictate the treatment options. Adjacent vascular enlargement is not a usual cause of Guyon's canal compression and a few case reports were reported in the literature. Surgical treatment by opening and releasing the roof of Guyon's canal and removing the aneurysm helped to achieve good outcome in most reports. CONCLUSION: Guyon's canal syndrome is less frequent than both cubital tunnel syndrome or carpal tunnel syndrome and many causative agents have been described. Vascular lesions are not the usual cause of compressing the ulnar nerve at the wrist and through this case we spotlighted this entity as another possible etiology requiring an adequate treatment for a better outcome.

Comparison of the efficacy and safety of vertebroplasty with different pedicle approaches for osteoporotic vertebral.

OBJECTIVE: To compare the efficacy and safety of vertebroplasty through different pedicle approaches in the treatment of osteoporotic vertebral compression fracture osteoporotic vertebral compression fractures (OVCF) by network meta-analysis. METHODS: Pubmed, Embase, Cochrane Library, Web of Science. Database for literature retrieval, retrieval time from the establishment of the database to April 2023, the randomized controlled trials of unilateral vertebroplasty (UVP), bilateral vertebroplasty (BVP), unilateral kyphoplasty (UKP), bilateral kyphoplasty (BKP), curved vertebroplasty (CVP) and curved kyphoplasty (CKP) were screened, evaluated and the data were extracted and included in the analysis. STATA 15.0 and ReMan 5.3 were used for data analysis. This study was registered in the National Institute for Health Research (NIHR) with the registration number CRD42023405181. RESULTS: This study included 16 articles with a total of 1712 patients. The order of visual analogue scale (VAS) improvement from good to bad is CVP > BVP > UVP > CKP > BKP > UKP. The order of kyphotic angles improvement from good to bad is CKP > UKP > UKP > UVP > BVP > CVP. The order of bone cement injection from less to more is UVP > CVP > UKP > CKP > BVP > BKP. The order of bone cement leakage rate from less to more is CKP > CVP > UKP > BKP > UVP > BVP. The order of X-ray exposure time from less to more is CKP > CVP > UVP > BVP > UKP > BKP. The order of operation time from less to more is CVP > UVP > UKP > CKP > BVP > BKP. CONCLUSION: For patients with kyphotic angles, kyphoplasty has unique advantages in improving kyphotic angles. But generally speaking, curved approach can optimize the distribution of bone cement through unilateral approach to achieve the orthopedic effect of bilateral approach, which is a minimally invasive technique with better curative effect and higher safety in the treatment of OVCF.

Stability before and after percutaneous anterior medullary fixation of lateral compression 1 and 2 pelvic ring disruptions: Should surgeons prioritize the anterior ring?

PURPOSE: Surgical intervention for lateral compression (LC) 1 and 2 pelvic ring fractures is controversial. Posterior ring stabilization remains the most common mode of initial fixation. However, greater mechanical instability is observed in the anterior component of LC pelvic fractures. This study tested whether reduction and percutaneous superior ramus fixation will decrease the instability of LC pelvic fractures on intraoperative fluoroscopic imaging. METHODS: All adult patients (≥ 18 years) presenting with either a Young-Burgess LC1 or LC2 pelvic ring disruption treated operatively with percutaneous anterior followed by posterior fixation by a single surgeon from July 2021 to June 2023 were retrospectively reviewed. Displacement of the anterior ring to intraoperative manual internal rotation stress examination under fluoroscopy was compared before and after anterior pelvic ring reduction and fixation and prior to posterior pelvic ring fixation. Pre- and post-operative visual analog scores (VAS) for pain were also compared. RESULTS: Twenty-one patients with a mean age of 48.7 years were included. Fifteen patients (71.4%) presented with an LC1, and six (28.6%) with an LC2 injury patterns. Anterior pelvic fixation alone provided 7.5mm reduction in mean displacement of the anterior pelvic ring (pre-operative = 9.2 mm vs. post-operative = 1.6 mm, p < 0.001). VAS significantly decreased from 7.2 one-day pre-operatively to 2.2 twenty-four h post-operatively (p < 0.001). CONCLUSIONS: Reduction and fixation of the anterior pelvic ring prior to posterior fixation for LC1 and LC2 pelvic ring disruptions substantially improves mechanical stability on intraoperative stress examination. Combination of percutaneous anterior and posterior fixation significantly decreased VAS above the MCID 24 h after stabilization.

A Case With Twists and Turns: A Report of Vertebrobasilar Dolichoectasia.

Vertebrobasilar dolichoectasia (VBD) is a rare anatomical abnormality of the vertebral artery system, defined as irregular expansion, elongation, and tortuosity of vertebral arteries. Anomalies of the vertebrobasilar artery can have a wide variety of clinical presentations, ranging from simple headaches to debilitating strokes. We present the case of an atypical presentation of VBD which mimicked trigeminal neuralgia by compressing the trigeminal nerve. There are currently no guidelines concerning the management of VBD, nor is there evidence of a definitive cure. This case invoked discussions among the medical team as to whether management should be medically or surgically focused, as well as long-term outcomes for patients with VBD. The superiority of medical versus surgical treatment of this issue is still a debated topic. This patient trialed medical management with dexamethasone and carbamazepine with no improvement in symptoms. He then underwent surgical gamma knife treatment but even this invasive measure was unsuccessful at relieving his symptoms. We hope that by presenting this case, we can display how the therapies available for VBD are limited and often unsuccessful in relieving the disease burden in patients with VBD.

Accuracy of an artificial intelligence algorithm for detecting moderate-to-severe vertebral compression fractures on abdominal and thoracic computed tomography scans.

Objective: To describe the accuracy of HealthVCF, a software product that uses artificial intelligence, in the detection of incidental moderate-to-severe vertebral compression fractures (VCFs) on chest and abdominal computed tomography scans. Materials and Methods: We included a consecutive sample of 899 chest and abdominal computed tomography scans of patients 51-99 years of age. Scans were retrospectively evaluated by the software and by two specialists in musculoskeletal imaging for the presence of VCFs with vertebral body height loss > 25%. We compared the software analysis with that of a general radiologist, using the evaluation of the two specialists as the reference. Results: The software showed a diagnostic accuracy of 89.6% (95% CI: 87.4-91.5%) for moderate-to-severe VCFs, with a sensitivity of 73.8%, a specificity of 92.7%, and a negative predictive value of 94.8%. Among the 145 positive scans detected by the software, the general radiologist failed to report the fractures in 62 (42.8%), and the algorithm detected additional fractures in 38 of those scans. Conclusion: The software has good accuracy for the detection of moderate-to-severe VCFs, with high specificity, and can increase the opportunistic detection rate of VCFs by radiologists who do not specialize in musculoskeletal imaging.

Objetivo: Descrever a acurácia do software HealthVCF na detecção incidental de fraturas compressivas de corpos vertebrais moderadas a graves em exames de tomografia computadorizada do tórax e abdome. Materiais e Métodos: Foram incluídos 899 exames consecutivos de pacientes com idades entre 51 e 99 anos. As imagens foram retrospectivamente avaliadas pelo software e por dois radiologistas especializados em musculoesquelético que investigaram fraturas compressivas de corpos vertebrais com perda da altura somática > 25%. A análise comparativa foi realizada entre o software e um radiologista geral, usando a avaliação do especialista como referência. Resultados: O software apresentou uma acurácia de 89,6% (IC 95%: 87,4­91,5%) para fraturas compressivas moderadas a graves, com sensibilidade de 73,8%, especificidade de 92,7% e valor preditivo negativo de 94,8%. Entre as 145 tomografias positivas detectadas pelo software, o radiologista geral deixou de relatar as fraturas em 62 (42,8%) e o algoritmo detectou fraturas adicionais em 38 dessas tomografias. Conclusão: O software possui boa acurácia na detecção de fraturas compressivas moderadas a graves, com alta especificidade, podendo aumentar a taxa de detecção oportunística dessas fraturas por radiologistas não especializados em musculoesquelético.

Nonlinear dynamics of two electromechanical arms acting discontinuously on a balloon under the action of a sinusoidal excitation.

Compression systems based electromechanical actuators require a good understanding of their dynamics for a better performance. This paper deals with the study of the nonlinear dynamics of an electromechanical system with two rotating arms subjected to a sinusoidal excitation for fluid compression purposes. The physical model integrating two balloons to be compressed by the arms alternately is presented and the mathematical equations traducing their dynamics are established. We emphasize on the influence of some control parameters namely the supply voltage, the discontinuity position and the viscoelastic ratio on the behaviour of the angular displacement of the arms. The study is also done by neglecting the inductance in the electrical part of the system. It is obtained that while the arms exhibit periodic motion during regular movement, compression of the balloons induces a shift to multi-periodic or chaotic dynamics, occasionally reverting to periodicity. Experimental and numerical simulation results demonstrate good agreement, with the R-system approximating more experimental outcomes than the RL-system. These findings hold significant implications for various environmental applications utilizing pump technology.

Pseudotumoral calcinosis of the elbow with ulnar and radial nerve deficits.

We report here a rare case of an acute peripheral nerve compression by pseudotumoral calcinosis (PCT) at the right elbow in a patient with severe tertiary hyperaparathyroidism. This complication required urgent multidisciplinary management. Surgical decompression by PCT resection enabled rapid motor and sensory recovery.

Personalized compression therapeutic textiles: digital design, development, and biomechanical evaluation.

Physical-based external compression medical modalities could provide sustainable interfacial pressure dosages for daily healthcare prophylaxis and clinic treatment of chronic venous disease (CVD). However, conventional ready-made compression therapeutic textiles (CTs) with improper morphologies and ill-fitting of pressure exertions frequently limit patient compliance in practical application. Therefore, the present study fabricated the personalized CTs for various subjects through the proposed comprehensive manufacturing system. The individual geometric dimensions and morphologic profiles of lower extremities were characterized according to three-dimensional (3D) body scanning and reverse engineering technologies. Through body anthropometric analysis and pressure optimization, the knitting yarn and machinery variables were determined as the digital design strategies for 3D seamless fabrication of CTs. Next, to visually simulate the generated pressure mappings of developed CTs, the subject-specific 3D finite element (FE) CT-leg modelings with high accuracy and acceptability (pressure prediction error ratio: 11.00% ± 7.78%) were established based on the constructed lower limb models and determined tissue stiffness. Moreover, through the actual in vivo trials, the prepared customized CTs efficiently (Sig. <0.05; ρ = 0.97) distributed the expected pressure requirements referring to the prescribed compression magnitudes (pressure error ratio: 10.08% ± 7.75%). Furthermore, the movement abilities and comfortable perceptions were evaluated subjectively for the ergonomic wearing comfort (EWC) assessments. Thus, this study promotes the precise pressure management and clinical efficacy for targeted users and leads an operable development approach for related medical biomaterials in compression therapy.