Internal Chambers Research Articles

Morphometry and morphology of the gypsum tumuli from the Sorbas karst region, SE Spain

In the Sorbas region of Spain, the gypsum karst is known for occurrences of gypsum tumuli, the peculiar weathering landforms that appear on gypsum rocks in semi-arid areas. Tumuli are small-scale domes (diameter: < 15 m, height: < 1.35 m) with empty internal chambers formed by local detachment and uplift of the surface layer of gypsum bedrock. Their origin is attributed to cyclic wetting and drying and expansive re-precipitation of gypsum in near-surface voids and pores of the rocks. Morphometric and morphological analyses of these gypsum landforms were conducted to verify and supplement data regarding their morphology. Based on linear regression equations, the geometry of the tumuli was analyzed quantitatively using pairs of the following parameters: horizontal long and short axes, relative height, thickness of the uplifted rock layer, height of the internal chamber, and others. The tumuli are limited in size – they rarely exceed 4.0 m in horizontal extension and 0.5 m in height above the surface of the surrounding terrain. Regardless of their size, they tend to preserve a rather constant plan shape, from circular to elliptical. The relative height of the tumuli is as a rule 7 to 8 times smaller than the length of their long horizontal axis, and ca. 6 times smaller than the length of the short axis. Aerial photogrammetry was used to estimate the destruction degree of gypsum tumuli, which helps to interpret their morphological changes during erosion. The appearance of a hole at the top of the form leads to the development of narrow-crater and then wide-crater tumuli. The side inlet opening leads to the formation of half-moon and then sickle shaped tumuli.

Low‐Volume Cores for Fabrication of Compact, Versatile, and Intelligent Soft Systems

AbstractThis study introduces the low‐volume core (LVC) fabrication method, which enables the monolithic molding of compact, complex, versatile, and intelligent soft robotic systems. This method uses thin and flexible thermoplastic sheets to mold internal chambers in soft fluidic actuators, valves, and circuits. The LVC fabrication method creates low‐volume networks in soft actuators (LV‐net actuators) that can be made with compact and complex geometries, enabling both low actuation volume input and multi‐degree‐of‐freedom actuators. LVC fabrication can also be used for compact, completely soft, and monolithic logic components (valves with low‐volume core, also called as LV valves) to provide directional resistance as well as a switching mechanism that enables fluidic logic in soft systems. The compatibility of the fabrication methods for both soft actuators and valves facilitates the creation of compact, integrated, and versatile soft robotic systems with embodied intelligence. This study introduces two examples of such intelligent soft robotic systems that integrate both LV‐net actuators and LV valves to demonstrate capability for complex system fabrication.

Research on thermodynamic modeling and temperature prediction of double flapper-nozzle servo valves

The thermal characteristic design of the aerospace servo valve is of significant importance due to the high temperature operating conditions. This paper aims to study the law of temperature variation of the internal chambers and shell of the servo valve while it is driven dynamically, in order to ensure that the components inside the servo valve work within an acceptable temperature range and avoid failure. This paper establishes thermodynamic models of the nozzle flapper assembly and the spool valve, as well as the whole servo valve, using the control volume method. The models consider the throttling heating generation of each throttling component in the servo valve and heat exchange between the shell and air. Based on these models, the temperature curves of the shell and oil in each chamber in the servo valve are simulated and analyzed, given a specified input signal. Finally, a test is conducted, and the results demonstrate that the temperature curve trend obtained through simulation and test is reasonable and more accurately reflects the internal temperature characteristics of servo valves. This research provides a reference for further studies on the internal heating mechanism of servo valves and the fault diagnosis of servo valves at high temperatures.

Reinforcement of Teeth Having Reenacted Perforating Internal Resorption Cavities After Repair Using Different Calcium Silicate-based Cements and Backfilling Materials: An In vitro Study

ABSTRACT To evaluate the fracture resistance (FR) of the teeth having reenacted perforating internal resorption cavities repaired by distinctive calcium silicate-based cements (CSCs) specifically: Endocem MTA, Biodentine, NeoMTA Plus, and backfilling materials. Ninety-six freshly extracted human mandibular premolar teeth were selected. Twelve roots were used as the negative control group. Rotary files were used to complete the final irrigation and root canal preparation on the remaining teeth. Following that, burs were used to make standardized internal resorption chambers in the middle part of the roots. Twelve of these samples were used as positive control samples. The remaining 72 root canals were obturated in the apical 4 mm using a single-cone approach, and they were separated into 6 groups based on the CSCs used to fill voids and the materials used as backfilling. Group 1: Endocem MTA (resorption) + Endocem MTA (coronal), Group 2: Endocem MTA (resorption) + Gutta-percha/sealer (coronal), Group 3: Biodentine (resorption) + Biodentine (coronal), Group 4: Biodentine (resorption) + Gutta-percha/sealer (coronal), Group 5: NeoMTA Plus (resorption) + NeoMTA Plus (coronal), and Group 6: NeoMTA Plus (resorption) + Gutta-percha/sealer (coronal). Specimens were inserted in acrylic resin and then subjected to fracture testing. Fracture strength tests were performed using a Universal Testing Machine. The force was employed vertically with a consistent speed of 1 mm/minute. The results were analyzed with Variance and Bonferrini tests at P &lt; 0.005. The mean force of fracture values were 447.00, 201.25, 318.75, 187.50, 596.58, 258.75, 347.50, and 298.75 N for Group 1, 2, 3, 4, 5, 6, 7, and 8, respectively. “There was a significant difference (P &lt; 0.001) between the experimental groups and the control group”. Group 5 showed the highest FR as compared to other groups. Backfilling with CSCs appears to be a better material than a gutta-percha/sealer combination. Neo MTA plus furthermore appeared the highest fracture-resistant material, while Biodentine + Gutta percha/sealer showed the least FR.

Experimental Investigation on Noise and Vibration of an Internal Combustion Engine with Oxyhydrogen Decarbonization

&lt;div&gt;Internal combustion engines are prone to get carbon deposits or residue which accumulate due to incomplete fuel combustion. This can have adverse effects on engine efficiency and performance. Engine decarbonization is one of the recent technologies in automobile maintenance, which involves the removal of carbon deposits or residue from various components within the internal combustion engine, including valves, pistons, cylinder heads, and combustion chambers. Decarbonization methods typically utilize specialized cleaning agents or additives to dissolve and eliminate these carbon deposits claiming to enhance engine performance and restoring optimal functionality. This article focuses to study the effects of engine decarbonization on noise and vibration of an IC engine. Oxyhydrogen (HHO) carbon cleaning machine has been used for decarbonization of the engine. This research addresses a contemporary concern in automotive maintenance by investigating the potential benefits of decarbonization in reducing noise and vibration levels. The results obtained from the data analysis provide insights into the effectiveness of the HHO carbon cleaning in improving engine performance. After decarbonization, the average noise levels have been observed to be decreased by an average of 3.28%, with a maximum reduction of 8.42% at a specific location and RPM value. Additionally, the vibration levels decreased by an average of 3.44%, with a maximum reduction of 16.38% at a particular location and RPM value.&lt;/div&gt;

Fast and Accurate Generation Method of Geometric Digital Twin Model of RC Bridge with Box Chambers Based on Terrestrial Laser Scanning

Digital Twin (DT) plays a crucial role in intelligent bridge management, and the geometric DT (gDT) serves as its foundation. Notably, the fast and high-precision generation of bridge gDT models has gained increasing attention. This research presents a method for generating high-precision and fast RC bridges with chambers for gDT using terrestrial laser scanning. The method begins with a proposed fast point cloud data collection technique designed specifically for bridges with internal chambers. Subsequently, Euclidean clustering and grid segmentation algorithms are developed to automatically extract contour features from the sliced point clouds. Finally, a framework based on the Dynamo–Revit reverse modelling method is introduced, enabling the automatic generation of gDT models from the identified point cloud features. To validate the feasibility and accuracy of the proposed method, a concrete variable section bridge is used. A comparison is made between the generated gDT model and the point cloud model in terms of 3D deviation, revealing a maximum deviation of 6.6 mm and an average deviation of 3 mm. These results affirm the feasibility of the proposed method.

Multichamber PLGA Microparticles with Enhanced Monodispersity and Encapsulation Efficiency Fabricated by a Batch‐Microfluidic Hybrid Approach

Microparticles with multiple internal chambers hold great promise as drug delivery systems due to their ability to sustain the release of drugs with short half‐lives. However, conventional batch methods used for their fabrication have limitations in terms of encapsulation efficiency and particle size distributions, while microfluidic methods suffer from low production efficiency. Herein, a batch‐microfluidic hybrid method is presented for fabricating poly(DL‐lactic‐co‐glycolic acid) (PLGA) polymeric microparticles with uniformly distributed, multiple inner microchambers. A scalable batch method is utilized for primary water‐in‐oil (W/O) emulsions, combined with a precise microfluidic approach for generating controlled secondary emulsions. This approach results in highly uniform PLGA microparticles with tunable size and improved encapsulation efficiency. Additionally, the effect of polydopamine‐based surface hydrophilic modification of microfluidic channels on drug encapsulation efficiency is investigated, achieving an efficiency of approximately 85%. The prepared multichamber PLGA microparticles exhibit an extended‐release profile without initial burst release, demonstrating their potential for sustained drug delivery in various biomedical applications.

Modeling of a two-degree-of-freedom fiber-reinforced soft pneumatic actuator

AbstractFiber winding reinforcement is widely used in soft robotic manipulators actuated by pressurized fluids. However, the specific effect of each type of winding on the bending motion of a tubular soft robotics manipulator with three chambers has not been explored widely. We present the development of precise finite element (FE) simulations and investigate the effect of helical fiber winding parameters on the bending motion of a two-degree-of-freedom manipulator with three internal chambers. We first show the development of an FE simulation that optimizes convergence and computational time and precisely matches the behavior of soft robots in practice. Compared to single-chamber robots, simulating three-chamber designs is more challenging due to the complex geometry. We then apply our FE model to simulate all the parameter variations. We show that for helical winding with a constant pitch, the closer the center of a chamber is to the intersection of the windings, the lower the bending stiffness of the chamber is. To minimize bending stiffness variation in different bending directions, the optimal angle between the center of the first chamber and the intersection of the two helical windings are 0° and 12°. Reducing the pitch of the helical windings or using other types of windings (i.e., ring winding or six helical winding) reduces the stiffness variation across different bending directions. The FE simulations are compared with experiments showing that the model can capture complex bending behaviors of the manipulator, even though the estimation tends to be less accurate at higher bending angles.

Full-scale analysis of smart fluid-filled barrier technology: Numerical and experimental study of fixture configurations

Roadside barriers are often deployed to prevent vehicles from colliding with roadside obstacles or hazards and from leaving the road surface. These barriers primarily take the form of guardrails or crash cushions and are designed to absorb energy through severe plastic deformation. Due to the severity of these types of collisions, the energy-absorbing mechanisms can fail resulting in the barrier becoming a hazard. To address this issue, a (US Patented) multi-chambered, smart fluid-filled barrier technology (SFFBT) was proposed as a potential replacement for such roadside barriers. This new patented technology utilizes fluid transport between the internal chambers and viscous dissipation as an additional energy-absorbing mechanism to help reduce the effects the severe deformation imparts on the colliding vehicle and its occupants. Numerical models were developed in ABAQUS dynamic explicit environment, and full-scale experimental testing was conducted at the Midwest Roadside Safety Facility of the University of Nebraska—Lincoln. Three barrier configurations were considered for this study with two different fluid levels resulting in six unique test samples. The three test configurations were (a) free-standing, (b) abutted against a rigid backstop, and (c) anchored. Fluid levels chosen were 25% and 33% filled volume. The results show that the proposed designs and fluid addition provided an increase in energy absorption while decreasing overall deformation stroke by up to 5%. Additionally, kinetic energy reduction increased by 15% with a nearly 140% increase in fluid energy dissipation. The best-performing configurations were the rigid backstop cases, followed by anchored and free-standing configurations. The effects of varying anchoring schemes provide additional performance evaluations for maximizing the energy-absorbing performance of the SFFBT system for use as an impact attenuator.

Feeling the beat: a smart hand exoskeleton for learning to play musical instruments.

Individuals who have suffered neurotrauma like a stroke or brachial plexus injury often experience reduced limb functionality. Soft robotic exoskeletons have been successful in assisting rehabilitative treatment and improving activities of daily life but restoring dexterity for tasks such as playing musical instruments has proven challenging. This research presents a soft robotic hand exoskeleton coupled with machine learning algorithms to aid in relearning how to play the piano by 'feeling' the difference between correct and incorrect versions of the same song. The exoskeleton features piezoresistive sensor arrays with 16 taxels integrated into each fingertip. The hand exoskeleton was created as a single unit, with polyvinyl acid (PVA) used as a stent and later dissolved to construct the internal pressure chambers for the five individually actuated digits. Ten variations of a song were produced, one that was correct and nine containing rhythmic errors. To classify these song variations, Random Forest (RF), K-Nearest Neighbor (KNN), and Artificial Neural Network (ANN) algorithms were trained with data from the 80 taxels combined from the tactile sensors in the fingertips. Feeling the differences between correct and incorrect versions of the song was done with the exoskeleton independently and while the exoskeleton was worn by a person. Results demonstrated that the ANN algorithm had the highest classification accuracy of 97.13% ± 2.00% with the human subject and 94.60% ± 1.26% without. These findings highlight the potential of the smart exoskeleton to aid disabled individuals in relearning dexterous tasks like playing musical instruments.

Description of a Titanosauriform (Sauropoda, Dinosauria) Cervical Vertebra from the Lower Cretaceous Kanmon Group, Southwestern Japan

A fragmentary and the largest single bone element from the Lower Cretaceous Kanmon Group in Kyushu Island, southwestern Japan reported yet to date is described. This specimen has a fossa and lenticular foramen on its lateral surface and internal chambers of both large and small sizes. It was identified as the cervical vertebra of a titanosauriform sauropod dinosaur mainly based on such pneumatic structure. This specimen represents the first titanosauriform to be described from the Kanmon Group.

Can diesel internal injector deposits form via an electrokinetic mechanism?

A hypothetical electrokinetic mechanism of wear and deposition inside fuel injectors has been analysed theoretically and experimentally. It involves conjugated electrokinetic and earthing electric currents. The flow of fuel through the orifice of the injector produces a streaming current proportional to the ς-potential of the metal|fuel interface. The streaming current leads to an accumulation of streaming potential between the fuel in the combustion chamber and the fuel in the internal injector chambers. This potential drives an earthing current, which, at steady state, compensates the streaming current. The earthing requires electrochemical reactions to transfer charge through the metal|fuel interface of the internal parts of the injector. The hypothesis investigated here is that the reactions produce ion-radicals, which (i) initiate radical chains leading to oxidized deposit formation; (ii) produce fuel-insoluble electrolytic products. The hypothesis is tested experimentally using a rig where current is passed through two steel electrodes in fully formulated diesel at constant voltage. Accumulation of oxidation products (gum) in the diesel is observed with and without current, up to phase separation. The rate of deposition in the rig is found to be dominated by direct oxidative degradation rather than the electrokinetic mechanism.

Numerical investigation of novel 3D-SPA for gripping analysis in multi-environment

The soft pneumatic actuator (SPA) has strong flexibility and good compliance, allowing its assembly into a multi-functional soft gripper that can be applied to object grasping and handling, post-disaster rescue, rehabilitation training, and in other fields. However, many actuators have limited grasping modes and can only bend in a single direction. And most of the soft grippers are studied in free space for grasping. Herein, a novel 3D-SPA with internal bellows chambers, inspired by the structure of the bird claws and the human fingers, is presented. Based on Yeoh hyperelasticity theory and virtual work principle, the mechanical theoretical model between different input air pressure Pin and the bending angle θ of the actuator is established, and the spatial conversion relationship of obstacle avoidance motion is given. The influence of the length and number of the chamber, the radius of the circular section, the shape of the cross section and the length of the joint on the bending performance and stress distribution of the actuator are studied in detail, respectively. Two soft grippers with different structures, composed of 3D-SPA, have a variety of bending configurations on different planes, which improves the inclusiveness of grasping objects with different shapes and sizes. Finally, the process of object grasping in free space and obstacle avoidance grasping and handling in obstacle space are studied respectively. The validity of the proposed mechanical model and spatial transformation relationship are verified. The investigation results reveal that the developed scheme assists the robot’s obstacle avoidance and grasping, which can be integrated into industrial robotic arms and AGVs for mobile operations and applied to rehabilitation training to help patients gradually recover hand joint function.

Internal structure of Cambrian vendobionts Arumberia, Hallidaya, and Noffkarkys preserved by clay in Montana, USA

Quilted fossils known as vendobionts have remained enigmatic because preserved as unrevealing impressions in sandstone, for example, Arumberia banksi Glaessner &amp; Walter, Noffkarkys storaasli Retallack &amp; Broz, and Hallidaya brueri (Wade) Retallack &amp; Broz from the Ediacaran to Cambrian, Grant Bluff and Arumbera formations of central Australia. These same species are reported here in shaley facies of the Early Cambrian Flathead Sandstone of Fishtrap Lake, Montana. These fossils preserved in three dimensions are infiltrated by clay and confirm that each taxon has distinctive internal chambers reflecting segmentation seen on the surface. Sedimentary structures, petrography and geochemistry of the Montana sediments are evidence that Arumberia, Noffkarkys and Hallidaya lived on supratidal flats of a wave-protected rock-bound estuary unaffected by marine bioturbation, and represent intertidal to supratidal ecosystems widespread from the Ediacaran to Cambrian.

Micro-CT to study and reconstruct fetal and infant coronary arteries: a pilot study on a novel post-mortem technique

For a significant part of infant and fetal deaths, specific pathophysiologic processes cannot be recognized. Thus, the scientific community is called to identify novel post-mortem diagnostic tools. This manuscript proposes the results of a pilot study which reports a novel post-mortem technique to study and reconstruct fetal/ infant coronary arteries. The study included human fetuses characterized by the absence of macroscopic cardiac abnormalities at postmortem in situ examination. For the study of fetal hearts, it was used a curing radiopaque silicone rubber compound (which solidified after injection in the coronary arteries) and an X-Ray microtomography (micro-CT). After micro- CT scans, coronary arteries’ branches were reconstructed throughout a specific software. At injection, it was possible to macroscopically evaluate coronary arteries’ perfusion. The analysis of the three-dimensional reconstructions highlighted that the aforementioned compound reached deep branches too. This approach can be considered a novel post-mortem technique for fetal/infant hearts. Nevertheless, the manuscript also discussed the following limitations: in some spots, coronary arteries’ reconstruction appeared interrupted; the compound also perfused parts of internal cardiac chambers. Until now, in the literature there are not methods that allow study with reconstruction of fetal/infant coronary arteries throughout micro-CT. The present paper pointed out the first indications for the application of this technique in human samples.

Cryo-EM structures of human A2ML1 elucidate the protease-inhibitory mechanism of the A2M family

A2ML1 is a monomeric protease inhibitor belonging to the A2M superfamily of protease inhibitors and complement factors. Here, we investigate the protease-inhibitory mechanism of human A2ML1 and determine the structures of its native and protease-cleaved conformations. The functional inhibitory unit of A2ML1 is a monomer that depends on covalent binding of the protease (mediated by A2ML1’s thioester) to achieve inhibition. In contrast to the A2M tetramer which traps proteases in two internal chambers formed by four subunits, in protease-cleaved monomeric A2ML1 disordered regions surround the trapped protease and may prevent substrate access. In native A2ML1, the bait region is threaded through a hydrophobic channel, suggesting that disruption of this arrangement by bait region cleavage triggers the extensive conformational changes that result in protease inhibition. Structural comparisons with complement C3/C4 suggest that the A2M superfamily of proteins share this mechanism for the triggering of conformational change occurring upon proteolytic activation.

Development of a Localized Drug Delivery System with a Step-by-Step Cell Internalization Capacity for Cancer Immunotherapy.

How to precisely reprogram tumor-associated macrophages (TAMs) and combine them with immunogenic cell death (ICD) is still a great challenge in enhancing the antitumor immunotherapeutic effect. Here, we developed a localized drug delivery system with a step-by-step cell internalization ability based on a hierarchical-structured fiber device. The chemotherapeutic agent-loaded nanomicelles are encapsulated in the internal chambers of the fiber, which could first be internalized by actively targeting tumor cells to induce ICD. Next, the rod-like microparticles can be gradually formed from long to short shape through hydrolysis of the fiber matrix in the tumor microenvironment and selectively phagocytosed by TAMs but not to tumor cells when the length becomes less than 3 μm. The toll-like receptors 7 (TLR7) agonist imiquimod could be released from these microparticles in the cytoplasm to reprogram M2-like TAMs. The in vivo results exhibit that this localized system can synergistically induce an antitumor immune response and achieve an excellent antitumor efficiency. Therefore, this system will provide a promising treatment platform for cancer immunotherapy.

Energy efficient bioelectro-concentration and recovery system of nutrients from human urine by integrating forward osmosis

Human urine contains abundant nutrients, while separately collecting urine can significantly alleviate nutrient loads in existing wastewater treatment facilities. Herein,0020a novel forward osmosis integrated bioelectro-concentration and recovery system (OsBCRS) was developed to recover nutrient ions from urine. NH4+ and PO43– migrated out from urine and enriched in the internal chamber of OsBCRS driven by the self-generated electric field, which were further concentrated by water extraction from the integrated forward osmosis (FO) process, and finally recovered as struvite. The current density of OsBCRS reached 27.3 A m–3, which in turn drove the migration of NH4+-N (93.7 ± 1.6%) and PO43–-P (94.6 ± 0.8%) out from urine, and these separated nutrients were enriched by 9.4–9.5 times in the internal chambers. Subsequently, these enriched nutrients in the catholyte were 3.2-fold concentrated with 68.6% of volume reduction by FO. The system removed up to 83.4% of NH4+-N and 88.8% of PO43–-P, most of which were recovered as struvite taking advantage of reverse-fluxed Mg2+. The recovered struvite exhibited similar crystal structure and composition to that of standard struvite. The preliminary operating cost analysis of OsBCRS demonstrated that the revenue, including electricity generation and struvite recovery, could offset the operating cost. This study demonstrated highly efficient enrichment and recovery of nutrient ions from human urine by OsBCRS in a cost-effective way, and would encourage further exploration for nutrients recovery from wastes.

Energy Shaping Control of Hydraulic Soft Continuum Planar Manipulators

This letter investigates the model-based control of a class of soft continuum manipulators with hydraulic actuation that bend on a plane due to pressurization of one or more internal chambers. A port-Hamiltonian formulation is employed to describe the system dynamics, which includes the pressure dynamics of the hydraulic fluid. A new nonlinear control law is constructed with an energy-shaping approach, and it is combined with an adaptive observer to compensate the effect of unknown external forces. Stability conditions are investigated with a Lyapunov approach, and the effect of the tuning parameters and of key model parameters is discussed. The effectiveness of the controller is demonstrated with numerical simulations.

Analytical Modeling of Flowrate and Its Maxima in Electrochemical Bioelectronics with Drug Delivery Capabilities.

Flowrate control in flexible bioelectronics with targeted drug delivery capabilities is essential to ensure timely and safe delivery. For neuroscience and pharmacogenetics studies in small animals, these flexible bioelectronic systems can be tailored to deliver small drug volumes on a controlled fashion without damaging surrounding tissues from stresses induced by excessively high flowrates. The drug delivery process is realized by an electrochemical reaction that pressurizes the internal bioelectronic chambers to deform a flexible polymer membrane that pumps the drug through a network of microchannels implanted in the small animal. The flowrate temporal profile and global maximum are governed and can be modeled by the ideal gas law. Here, we obtain an analytical solution that groups the relevant mechanical, fluidic, environmental, and electrochemical terms involved in the drug delivery process into a set of three nondimensional parameters. The unique combinations of these three nondimensional parameters (related to the initial pressure, initial gas volume, and microfluidic resistance) can be used to model the flowrate and scale up the flexible bioelectronic design for experiments in medium and large animal models. The analytical solution is divided into (1) a fast variable that controls the maximum flowrate and (2) a slow variable that models the temporal profile. Together, the two variables detail the complete drug delivery process and control using the three nondimensional parameters. Comparison of the analytical model with alternative numerical models shows excellent agreement and validates the analytic modeling approach. These findings serve as a theoretical framework to design and optimize future flexible bioelectronic systems used in biomedical research, or related medical fields, and analytically control the flowrate and its global maximum for successful drug delivery.