318 research outputs found
Systemic tuberculosis presenting with acute transient myopia: a case report
<p>Abstract</p> <p>Introduction</p> <p>Transient myopia has been reported to occur in a number of conditions, either ocular in origin or associated with an underlying systemic cause. We present a rare case of this abnormality occurring in the setting of systemic tuberculosis.</p> <p>Case presentation</p> <p>A 29-year-old Indian woman presented with sudden onset blurred distance vision and fever. Examination revealed visual acuity of counting fingers in both eyes improving to 6/9 with pinhole with N5 reading acuity. Anterior segment examination revealed narrow angles on gonioscopy. Posterior segments were normal. Systemic examination revealed a fluctuant mass in her left loin, aspiration of which yielded pus which was culture-positive for <it>Mycobacterium tuberculosis</it>. The Mantoux test elicited a strongly positive reaction. Chest X-ray and magnetic resonance imaging of the brain were unremarkable. Computed tomography scan and magnetic resonance imaging of the spine and abdomen revealed a large psoas abscess communicating with the loin mass. Two vertebrae were involved but not the spinal cord or canal.</p> <p>Conclusion</p> <p>Transient myopia is a rare presenting feature of systemic tuberculosis. A postulated mechanism in this patient is that development of a uveal effusion related to systemic tuberculosis caused anterior rotation of the iris-lens diaphragm, thereby inducing narrowing of the angle and acute myopia.</p
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Recent progress of 4D printing in cancer therapeutics studies
Cancer is a critical cause of global human death. Not only are complex approaches to cancer prognosis, accurate diagnosis, and efficient therapeutics concerned, but post-treatments like postsurgical or chemotherapeutical effects are also followed up. The four-dimensional (4D) printing technique has gained attention for its potential applications in cancer therapeutics. It is the next generation of the three-dimensional (3D) printing technique, which facilitates the advanced fabrication of dynamic constructs like programmable shapes, controllable locomotion, and on-demand functions. As is well-known, it is still in the initial stage of cancer applications and requires the insight study of 4D printing. Herein, we present the first effort to report on 4D printing technology in cancer therapeutics. This review will illustrate the mechanisms used to induce the dynamic constructs of 4D printing in cancer management. The recent potential applications of 4D printing in cancer therapeutics will be further detailed, and future perspectives and conclusions will finally be proposed
Biologic Therapy for HLA-B27-associated Ocular Disorders
The treatment of articular and extra-articular manifestations associated with HLA-B27 has undergone dramatic changes over the past two decades, mainly as a consequence of the introduction of biologic agents and in particular anti-tumor necrosis factor α (anti-TNFα) agents. Uveitis is known to be the most frequent extra-articular feature in HLA-B27-associated spondyloarthritides. Topical corticosteroids and cycloplegic agents remain the cornerstones of treatment. However, biologic therapy may be effective in the management of refractory or recurrent forms of uveitis. This review gives an update on the management of HLA-B27-associated ocular disorders with biologics, including anti-TNFα agents and non-anti-TNFα biologic modifier drugs. There is an emerging role for newer biologics targeting interleukin-12/23 and interleukin-17 for the treatment of spondyloarthritides but data on their efficacy on anterior uveitis are sparse
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Topological design of cellular structures for maximum shear modulus using homogenization SEMDOT
This paper incorporates the homogenization theory into non-penalized Smooth-Edged Material Distribution for Optimizing Topology (SEMDOT) algorithm to conduct the design of cellular structures with the maximum shear modulus. The parametric study and comparison with existing results obtained by BESO are carried out. The numerical examples in 2D and 3D demonstrate the effectiveness of non-penalized SEMDOT in generating smooth cellular structures with the maximum shear modulus. Compared to BESO, SEMDOT can achieve comparable results and smoother boundaries. Smooth boundaries obtained by SEMDOT can facilitate the manufacturing of obtained cellular structures in 3D or 4D printing
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Multimaterial 4D printing with tunable bending model
Shape-memory polymer-based functional structures may now be produced more efficiently via four-dimensional (4D) printing, benefiting from the recent advances in multi-material three-dimensional (3D) printing technologies. Composite material design using 4D printing has opened new possibilities for customizing the shape memory property of smart polymers. This work studies a design strategy to harness desirable morphing by 4D printing multimaterial composites with a focus on the detailed finite element (FE) procedure, experimental results, and soft robotic application. Composites with bilayer laminates consisting of a shape-memory polymer (SMP) and a flexible elastomer are constructed with variable thickness ratios to control the self-bending of the composite. Finite element simulations are used to understand the underlying processes of composite materials and to generate accurate predictions for the experimental results, which reduces cost and development time. The application of 4D printing and multi-material composite programming is demonstrated with a soft robotic gripper for manipulating fragile objects
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Mechanical Strain Tailoring via Magnetic Field Assisted 3D Printing of Iron Particles Embedded Polymer Nanocomposites
The development of efficient, energy saving, eco-friendly and automated manufacturing of free-form variable-thickness polymer composite components has created a step-change and enabling technology for the composites industry seeking geometry tailoring during a mouldless and/or additive manufacturing such as that in 3D printing. The current article presents ongoing research on the 3D printing of polymer nanocomposites embedded with ferromagnetic iron particles. This research involves exposing the nanocomposite to a magnetic field remotely during the fabrication process. The magnetic field is applied unidirectionally by using constant-strength magnets placed on a fused deposition method (FDM) based 3D printing platform. The magnets are symmetrically fixed on both sides of the printed nanocomposite. A high-performance polylactic acid (PLA) grade polymer was selected, which is commonly used for rigid structures. The setup utilised Neodymium magnets with a constant strength below 1T. The printing process maintained a consistent temperature of 220°C for the nozzle and 40°C for the bed. Observations have shown that the nanocomposites being printed undergo permanent macro-scale deformations caused by the extrinsic strains induced by the surrounding iron particles in response to the relatively low magnetic field (<1T). To provide a theoretical understanding of these induced strains, a Multiphysics constitutive equation has been developed. This equation aims to describe the micromechanics of the field-induced strains and study the evolution of magnetisation within a relatively thick nanocomposite (5mm thickness). Experimental measurements have quantified the macro-scale geometric variations achieved during printing, and a correlation has been established between these variations and the extrinsic strains derived from the theoretical solution, i.e. induced 1.3 mm. The theoretical solution accurately provides the description of the actual field induced strains during the 3D printing process provided that precise temperature values for the layers are accounted for. The theory also predicts a high sensitivity of field induced deformation to such temperatures and interconnects the Multiphysics parameters in explicit expressions for the phenomenon occurring. The results demonstrate a viable and disruptive magnetic field equipped fabrication approach with ability to extend to geometry control during its process
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Novel linear piezo‐resistive auxetic meta‐sensors with low Young's modulus by a core–shell conceptual design and electromechanical modelling
Production of piezo-resistive auxetic sensors is usually carried out through mixing and coating methods. Although these methods are beneficial, Young's modulus of mixed sensors becomes high because of using a high percentage of sensing elements while the durability of coated sensors gets low due to the separation of sensing elements from the sensor surface. This article presents a new core–shell metamaterial model to address the mentioned problems. The shell and the core are produced of polydimethylsiloxane (PDMS) rubber and a mixture of PDMS/graphite powders (73.45 wt% graphite powders), respectively. A finite element model is developed via COMSOL software to predict the electromechanical behaviors of the created sensor and verified by an experimental study. Scanning electron microscope imaging is conducted to detect the separations of the graphite particles. The main important feature of this meta-sensor is to possess a linear sensitivity due to having zero Poisson's ratio. The advantage of this method is that Young's modulus of the sensor does not decrease (unlike the mixing method), and the sensor-coated particles do not separate from the sensor after a while (unlike the coating method). The introduced model has advantages that promote potential applications such as using sensory gloves to detect, for instance, human hand movements
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Combinational system of lipid-based nanocarriers and biodegradable polymers for wound healing: an updated review
Skin wounds have imposed serious socioeconomic burdens on healthcare providers and patients. There are just more than 25,000 burn injury-related deaths reported each year. Conventional treatments do not often allow the re-establishment of the function of affected regions and structures, resulting in dehydration and wound infections. Many nanocarriers, such as lipid-based systems or biobased and biodegradable polymers and their associated platforms, are favorable in wound healing due to their ability to promote cell adhesion and migration, thus improving wound healing and reducing scarring. Hence, many researchers have focused on developing new wound dressings based on such compounds with desirable effects. However, when applied in wound healing, some problems occur, such as the high cost of public health, novel treatments emphasizing reduced healthcare costs, and increasing quality of treatment outcomes. The integrated hybrid systems of lipid-based nanocarriers (LNCs) and polymer-based systems can be promising as the solution for the above problems in the wound healing process. Furthermore, novel drug delivery systems showed more effective release of therapeutic agents, suitable mimicking of the physiological environment, and improvement in the function of the single system. This review highlights recent advances in lipid-based systems and the role of lipid-based carriers and biodegradable polymers in wound healing
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