Interlaminar hygrothermal stresses in laminated plates

AbstractWithin the elasticity formulation the most general displacement field for hygrothermal problems of long laminated composite plates is presented. The equivalent single-layer theories are then employed to determine the global deformation parameters appearing in the displacement fields of general cross-ply, symmetric, and antisymmetric angle-ply laminates under thermal and hygroscopic loadings. Reddy’s layerwise theory is subsequently used to determine the local deformation parameters of various displacement fields. An elasticity solution is also developed in order to validate the efficiency and accuracy of the layerwise theory in predicting the interlaminar normal and shear stress distributions. Finally, various numerical results are presented for edge-effect problems of several cross-ply, symmetric, and antisymmetric angle-ply laminates subjected to uniform hygrothermal loads. All results indicate high stress gradients of interlaminar normal and shear stresses near the edges of laminates

Purification and Structure Elucidation of Novel Saponins from the Sea Cucumber Actinopyga spinea viscera Using HPCPC and Mass Spectrometry

Introduction: Sea cucumbers, sometimes referred to as marine ginseng, produce an assortment of bioactive compounds with diverse functions, and are potential sources of active ingredients for nutraceutical, pharmaceutical and cosmeceutical products. This project aimed to identify and characterize novel bioactive compounds from the sea cucumber Actinopyga spinea Cherbonnier, 1980, with an emphasis on the triterpene glycosides, saponins. Methods and Results: The sea cucumbers were extracted with 70% ethanol and this extract was purified by a liquid-liquid partition process and column chromatography using Amberlite XAD-4 resin, followed by iso-butanol extraction. The iso-butanol saponins-enriched mixture was further purified by high performance centrifugal partition chromatography (HPCPC). The resultant purified polar samples were analyzed using high performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF/ MS) and ESI-MS, and MS/MS to identify saponins and characterize their molecular structures. Further, the antifungal activity of saponins was examined against a few prevalent dermatophytes. As a result, at least 45 saponins were tentatively identified in the sea cucumber A. spinea with a high structural diversity, including 20 new sulfated and non-sulfated triterpene glycosides, containing different aglycone and sugar moieties. The TLC profiles of the purified saponins mixture and MALDI analyses revealed that this species possesses a unique pattern of saponins. Further, the purified saponins showed the potent antifungal activity against the examined dermatophytes. Conclusions: The high structural diversity and novelty of saponins from A. spinea with potential functional activities presents a great opportunity to exploit their applications for industrial, agricultural and pharmaceutical use

FIM: A fatigued-injured muscle model based on the sliding filament theory

Skeletal muscle modeling has a vital role in movement studies and the development of therapeutic approaches. In the current study, a Huxley-based model for skeletal muscle is proposed, which demonstrates the impact of impairments in muscle characteristics. This model focuses on three identified ions: H + , inorganic phosphate Pi and Ca 2+. Modifications are made to actin-myosin attachment and detachment rates to study the effects of H + and Pi. Additionally, an activation coefficient is included to represent the role of calcium ions interacting with troponin, highlighting the importance of Ca 2+. It is found that maximum isometric muscle force decreases by 9.5% due to a reduction in pH from 7.4 to 6.5 and by 47.5% in case of the combination of a reduction in pH and an increase of Pi concentration up to 30 mM, respectively. Then the force decline caused by a fall in the active calcium ions is studied. When only 15% of the total calcium in the myofibrillar space is able to interact with troponin, up to 80% force drop is anticipated by the model. The proposed fatigued-injured muscle model is useful to study the effect of various shortening velocities and initial muscletendon lengths on muscle force; in addition, the benefits of the model go beyond predicting the force in different conditions as it can also predict muscle stiffness and power. The power and stiffness decrease by 40% and 6.5%, respectively, due to the pH reduction, and the simultaneous accumulation of H + and Pi leads to a 50% and 18% drop in power and stiffness

Orbital Skull Base Reconstruction with Temporalis Muscle: The Sphenoid Keyhole Technique

The temporalis flap is a common flap used in head and neck reconstruction. In this article, the authors present a new modification of the use of the temporalis muscle flap for orbital skull base reconstruction with the use of a sphenoid keyhole. This technique confers multiple advantages in reducing the arc of rotation and providing a tension-free reconstruction of the orbital skull base

Multi-frequency piezomagnetoelastic energy harvesting in the monostable mode

The present article investigates effects of the multi-frequency excitation on the output power of a piezomagnetoelastic energy harvester. The piezomagnetoelastic power generator is assumed to operate in the mono-stable mode. A perturbation technique based on the method of multiple scales is employed to develop an analytical solution to nonlinear differential equations governing the system dynamics. In addition, a Runge-Kutta numerical scheme is used to solve the differential equations. It is shown that the perturbation solution is in a close agreement with the numerical solution. The system response is determined for several cases including super-harmonic, combination and simultaneous resonances. The steady-state output voltage is then obtained for each case and compared with that of a single-frequency excitation. Due to nonlinearities present in the system, a multi-frequency excitation gives rise to complicated phenomena such ascombination and simultaneous resonances. It is found out that exploiting these resonances can significantly increase the amount of energy harvested

Holmium Laser for Endoscopic Treatment of Benign Tracheal Stenosis

Introduction Laryngotracheal stenosis is a difficult problem with varied etiology and various treatment options. The holmium laser represents another tool for the treatment of benign tracheal stenosis. Objectives To determine the utility of holmium laser treatment for benign tracheal stenosis with regards to safety and efficacy. Methods This was a retrospective case study examining patients with benign tracheal stenosis from 1998–2016 who underwent holmium laser treatment. Determining the safety of this procedure was the primary goal, and complications were monitored as a surrogate of safety. Results A total of 123 patients who underwent holmium laser treatment for benign tracheal stenosis were identified. In total, 123 patients underwent 476 procedures, with follow-up ranging from 1 month to 14 years. No intraoperative or post-operative complications were identified as a direct result of the use of this particular laser. Conclusions The holmium laser is an effective and safe laser to use for tracheal stenosis treatment. It is a contact laser with a short acting distance, which reduces the risk of injury to distal airway structures. Given the favorable experience reported here, the holmium laser should be considered when tracheal surgery is attempted

A Full-Duplex Optical Millimeter Waves (60-100 GHz) Radio-over-Fiber System

In this paper, we propose and simulate the most compact full-duplex optical millimeter wave radio-over-fiber (mmW-RoF) system employing binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) with error-free transmission over 10, 25 and 50 km of single mode fibers (SMF) in up-link (UL) and down-link (DL). We evaluate the EVM values for DL and UL are < 24% for BPSK and QPSK over the 10, 25 and 50 km of SMF

Cytomegalovirus Infection in a Patient With Leukocyte Adhesion Deficiency Type 1

Leukocyte adhesion deficiency type 1 (LAD-1) is a rare autosomal recessive immunodeficiency disorder, characterized by recurrent bacterial and fungal infections without pus formation. Herein, we report a case of LAD-1 that developed into gastrointestinal cytomegalovirus (CMV) disease and manifested with persistent abdominal pain and bloody diarrhea. Although the presence of concurrent gastrointestinal CMV infection with LAD-1 is a rare condition, this case highlights the need for further research to evaluate the complex mechanisms between LAD-1 and CMV occurrence