An Analytical Energy Harvester Model for Interdigitated Ring Electrode on Circular Elastic Membrane

Energy harvesters are devices that accumulate ambient vibrational energy from the environment, and for the time being, variable capacitance is the most widely used mechanism. Various designs were proposed to increase the power of such devices, and in particular, the interdigitated electrode (IDE) pattern is the mainstream. Nevertheless, most IDE designs focus merely on the parallel-type vibrations of electrodes. In this study, the performance of a novel harvester, which combined circular membrane and interdigitated ring electrodes (IRE), was investigated. This design allows the device to collect energy from the rotational structure motions of electrodes through the vibrating membrane. Besides, the circular structure provides a dense capacitive arrangement that is higher than that of the arrangement obtained using regular rectangular chips. The IRE diagram is composed of many capacitive rings, each of which harvests vibrated energy simultaneously. Three gaps (1, 10, and 100 μm) of the ring are investigated for the first four vibrational modes of the membrane to understand the effect of energy output. It is found that the energy outputs are approximately the same for the three gaps; however, rings with a wider gap are easier to manufacture in MEMS.

Bioinspired Granular Media Friction Pad: A Universal System for Friction Enhancement on Variety of Substrates

The granular media friction pad (GMFP) inspired by the biological smooth attachment pads of cockroaches and grasshoppers employs passive jamming, to create high friction forces on a large variety of substrates. The granular medium inside the pad is encased by a flexible membrane which at contact formation greatly adapts to the substrate profile. Upon applying load, the granular medium undergoes the jamming transition and changes from fluid-like to solid-like properties. The jammed granular medium, in combination with the deformation of the encasing elastic membrane, results in high friction forces on a multitude of substrate topographies. Here we explore the effect of elasticity variation on the generation of friction by varying granular media filling quantity as well as membrane modulus and thickness. We systematically investigate contact area and robustness against substrate contamination, and we also determine friction coefficients for various loading forces and substrates. Depending on the substrate topography and loading forces, a low filling quantity and a thin, elastic membrane can be favorable, in order to generate the highest friction forces.

Pulmonary Guardians and Special Regulatory Devices in the Lung of Nile Monitor Lizard (Varanus niloticus) with Special Attention to the Communication Between Telocyte, Pericyte, and Immune Cells

Monitor lizards are acclimatized to a variety of environments. Most of the monitor species are terrestrial, although there are arboreal and semiaquatic monitors. Such accommodation requires unique cellular structure and regulatory devices in various organs, particularly their lungs. This study aimed to report the pulmonary guardians and special regulatory devices that may guard and promote the function of the lungs of the Nile monitor lizards (Varanus niloticus). Specially structured vessels were recorded in the pulmonary tissue involving atypical glomus vessels, vessels with variable wall thickness, and a venule with specialized internal elastic membrane. Moreover, numerous lung resident guardians could be identified including both alveolar and interstitial macrophages, dendritic cells, mast cells, and B- and T-lymphocytes. Pericytes were demonstrated surrounding the capillary endothelium with a characteristic direct hetero-cellular junction with telocytes. Telocytes established a microenvironment through an indirect hetero-cellular junction with the interstitial macrophage, dendritic cells, and pneumocyte type II. Collectively, these data indicate a significant role played by the specially structured vessels and the resident immune cells in guarding the pulmonary tissue of the Nile monitor lizards and promoting its function. Telocytes are suggested to play a key role in angiogenesis and cellular communication to promote the function of the immune cells.

Granular Media Friction Pad for Robot Shoes—Hexagon Patterning Enhances Friction on Wet Surfaces

For maximizing friction forces of the robotic legs on an unknown/unpredictable substrate, we introduced the granular media friction pad, consisting of a thin elastic membrane encasing loosely filled granular material. On coming into contact with a substrate, the fluid-like granular material flows around the substrate asperities and achieves large contact areas with the substrate. Upon applying load, the granular material undergoes the jamming transition, rigidifies and becomes solid-like. High friction forces are generated by mechanical interlocking on rough substrates, internal friction of the granular media and by the enhanced contact area caused by the deformation of the membrane. This system can adapt to a large variety of dry substrate topologies. To further increase its performance on moist or wet substrates, we adapted the granular media friction pad by structuring the outside of the membrane with a 3D hexagonal pattern. This results in a significant increase in friction under lubricated conditions, thus greatly increasing the universal applicability of the granular media friction pad for a multitude of environments.

Acute myocardial infarction with left main coronary artery ostial negative remodelling as the first manifestation of Takayasu arteritis: a case report

Background Takayasu arteritis is a chronic inflammatory disease involving the aorta and its major branches. Acute myocardial infarction rarely but not so much presents in patients with Takayasu arteritis, and the preferable revascularization strategy is still under debate. Case presentation A 22-year-old female with Takayasu arteritis presented with acute myocardial infarction. Coronary angiography and intravenous ultrasound (IVUS) showed that the right coronary artery (RCA) was occluded and that there was severe negative remodelling at the ostium of the left main coronary artery (LMCA). The patient was treated by primary percutaneous transluminal coronary angioplasty (PTCA) with a scoring balloon in the LMCA, without stent implantation. After 3 months of immunosuppressive medication, the patient received RCA revascularization by stenting. There was progressive external elastic membrane (EEM) enlargement of the LMCA ostium demonstrated by IVUS at 3 and 15 months post-initial PTCA. Conclusion Here, we report a case of Takayasu arteritis with involvement of the coronary artery ostium. Through PTCA and long-term immunosuppressive medication, we found that coronary negative remodelling might be reversible in patients with Takayasu arteritis.

MFAP4 Deficiency Attenuates Angiotensin II-Induced Abdominal Aortic Aneurysm Formation Through Regulation of Macrophage Infiltration and Activity

Objective: Abdominal aortic aneurysm (AAA) is a common age-related vascular disease characterized by progressive weakening and dilatation of the aortic wall. Microfibrillar-associated protein 4 (MFAP4) is an extracellular matrix (ECM) protein involved in the induction of vascular remodeling. This study aimed to investigate if MFAP4 facilitates the development of AAA and characterize the underlying MFAP4-mediated mechanisms.Approach and Results: Double apolipoprotein E- and Mfap4-deficient (ApoE−/−Mfap4−/−) and control apolipoprotein E-deficient (ApoE−/−) mice were infused subcutaneously with angiotensin II (Ang II) for 28 days. Mfap4 expression was localized within the adventitial and medial layers and was upregulated after Ang II treatment. While Ang II-induced blood pressure increase was independent of Mfap4 genotype, ApoE−/−Mfap4−/− mice exhibited significantly lower AAA incidence and reduced maximal aortic diameter compared to ApoE−/− littermates. The ApoE−/−Mfap4−/− AAAs were further characterized by reduced macrophage infiltration, matrix metalloproteinase (MMP)-2 and MMP-9 activity, proliferative activity, collagen content, and elastic membrane disruption. MFAP4 deficiency also attenuated activation of integrin- and TGF-β-related signaling within the adventitial layer of AAA tissues. Finally, MFAP4 stimulation promoted human monocyte migration and significantly upregulated MMP-9 activity in macrophage-like THP-1 cells.Conclusion: This study demonstrates that MFAP4 induces macrophage-rich inflammation, MMP activity, and maladaptive remodeling of the ECM within the vessel wall, leading to an acceleration of AAA development and progression. Collectively, our findings suggest that MFAP4 is an essential aggravator of AAA pathology that acts through regulation of monocyte influx and MMP production.

3D-mapping of human lymph node and spleen reveals integrated neuronal, vascular, and ductal cell networks

As secondary lymphoid organs, the spleen and lymph node represent important hubs for both innate and adaptive immunity. Neuroanatomical and tracing data, largely derived from rodents, suggest that lymph nodes contain sensory and sympathetic innervation, whereas the spleen contains postganglionic sympathetic innervation, with conflicting views regarding the existence of cholinergic or vagal innervation. Herein, we map the neuronal, vascular, and sinus cell networks from human spleen and lymph node using highly multiplexed CODEX (CO-Detection by indEXing) and 3D light sheet microscopy of cleared tissues. These data demonstrate striking delineation of two distinct layers within the lymph node subcapsular sinus-the ceiling defined by Podoplanin expression and floor by LYVE1, which overlays the lymph node follicles. Within the lymph node interior, we observed a mesh-like vessel network innervated with GAP43 and beta3-tubulin. Dense perivascular innervation occurred in both tissues, including a subset of axonal processes expressing choline acetyl transferase (ChAT). Four neuronal markers (ChAT, PGP9.5, tyrosine hydroxylase, and beta3-tubulin) localized to the arterial tunica externa suggest expression in the nervi vasorum while GAP43 was expressed within the internal elastic membrane of arteries. These data represent highly novel 3D visualization of perivascular and periductal autonomic innervation within these two key human organs.

The approximation of the solution of wave problems by spectral expansions connected with elliptic differential operators

In this research, we investigate the spectral expansions connected with elliptic differential operators in the space of singular distributions, which describes the vibration process made of thin elastic membrane stretched tightly over a circular frame. The sufficient conditions for summability of the spectral expansions connected with wave problems on the disk are obtained by taking into account that the deflection of the membrane during the motion remains small compared to the size of the membrane and for wave propagation problems, the disk is made of some thermally conductive material.

Development of Fin Propelled Unmanned Underwater Drone

The development of Unmanned Underwater Vehicle (UUV) in the recent decade has opened new applications in navy and marine platforms. UUV is either autonomous or radio-controlled robots that can operate underwater without a human occupant. Manoeuvrability must be considered with higher priority during the development stage of the drone. Any vehicle that mimics biological organisms has better performance and efficiencies. The UUV being fabricated is propelled with the help of two adulatory fins inspired by the locomotion of rays and cuttlefish and will be controlled wirelessly. Each fin mechanism is comprised of individually actuated fin rays, which are interconnected by an elastic membrane. An on-board microcontroller is used to generate the motion pattern that results in fin undulations which propels the UUV. The designed hull portion consists of electronic components with leakage proof and also holds the fin. An attempt has been made to develop the UUV with improved manoeuvrability and performance features.

Dense flow field interpolations from PTV data in the presence of generic solid boundaries

Three-dimensional flow measurements by Particle Tracking Velocimetry (PTV) provide scattered flow information, that often needs to be interpolated onto a regular grid. Therefore, the use of experimental data assimilation approaches such as VIC+ (Schneiders and Scarano, 2016) were proposed to enhance the instantaneously available spatial resolution limits beyond that of the PTV measurements. Nevertheless, there exists no prior attempt to perform the data assimilation when the flow is in direct contact with physical objects. Thus, in order to handle generic solid body intrusions within the flow fields of VIC+ application, the utilization of Arbitrary Lagrangian-Eulerian and immersed boundary treatment approaches of the computational fluid-structure interaction (FSI) frameworks are proposed. The introduced variants over the standard VIC+ are assessed with a high fidelity numerical test case of flow over periodic hills. The accuracy superiority of the flow field reconstructions with the proposed approaches are denoted especially in close proximity of the interaction surface. An experimental application of the introduced methods is demonstrated to compute the pressure distribution over an unsteadily moving elastic membrane surface, revealing the time-resolved interaction between the flow structures and the membrane deformations.