Latch Mechanism Research Articles

Characterization of two bacterial tyrosinases from the halophilic bacterium Hahella sp. CCB MM4 relevant for phenolic compounds oxidation in wetlands.

Tyrosinases (TYRs) are type-3 copper proteins that are widely distributed in nature. They can hydroxylate and oxidize phenolic molecules and are mostly known for producing melanins that confer protection against photo induced damage. TYRs are also thought to play an important role in the 'latch mechanism', where high concentrations of phenolic compounds inhibit oxidative decomposition of organic biomass and subsequent CO2 release, especially relevant in wetland environments. In the present study, we describe two TYRs, HcTyr1 and HcTyr2, from halophilic bacterium Hahella sp. CCB MM4 previously isolated at Matang mangrove forest in Perak, Malaysia. The structure of HcTyr1 was determined by X-ray crystallography at a resolution of 1.9 Å and represents an uncharacterized group of prokaryotic TYRs as demonstrated by a sequence similarity network analysis. The genes encoding the enzymes were cloned, expressed, purified and thoroughly characterized by biochemical methods. HcTyr1 was able to self-cleave its lid-domain (LID) in a protease independent manner, whereas the LID of HcTyr2 was essential for activity and stability. Both enzymes showed variable activity in the presence of different metals, surfactants and NaCl, and were able to oxidize lignin constituents. The high salinity tolerance of HcTyr1 indicates that the enzyme can be an efficient catalyst in the habitat of the host.

Carbon Sequestration and the Enzymic Latch Mechanism in Red, Black and White Mangrove Soils of Florida USA.

Carbon Sequestration and the Enzymic Latch Mechanism in Red, Black and White Mangrove Soils of Florida USA.

A Novel Hybrid Gripper Capable of Grasping and Throwing Manipulation

Throwing motion is known for phenomenally fast rearrangement, sorting tasks, and placing the object outside the limited workspace with less effort. However, in the robotics domain, despite many simple yet versatile, mechanically intelligent grippers reported earlier, they focus primarily on achieving robust grasping and dexterous manipulation. This article presents a novel design of a single actuator driven hybrid gripper with mechanically coupled rigid links and elastic gripping surface; this arrangement provides the dual function of versatile grasping and throwing manipulation. The gripper comprises a latching mechanism (LM) that drives two passive rigid fingers by elongating/releasing the coupled elastic strip. Elongating the gripping surface enables the gripper to adapt to objects with different geometries, vary surface contact force characteristics, and store the energy in the form of elastic potential. A mechanism to discharge the stored potential energy gradually or instantaneously is essential when the intended task is to place the object free from impact or away from the limited reachable workspace. The proposed LM can swiftly shift from a quick release to a gradual release of the stored elastic potential for greater object's acceleration during throwing and no acceleration while placing. By doing so, the object can be placed at the desired location even farther than the manipulator's reachable workspace. We report the proposed gripper's design details, development, and experimentally demonstrate the versatile grasping, impact-free placing, and throwing capabilities.

The effects of temperature on elastic energy storage and release in a system with a dynamic mechanical advantage latch.

Changes in temperature alter muscle kinetics and in turn affect whole-organism performance. Some organisms use the elastic recoil of biological springs, structures which are far less temperature sensitive, to power thermally robust movements. For jumping frogs, the use of elastic energy in tendons is facilitated through a geometric latching mechanism that operates through dynamic changes in the mechanical advantage (MA) of the hindlimb. Despite the well-documented use of elastic energy storage, frog jumping is a locomotor behavior that is significantly affected by changes in temperature. Here, we used an in vitro muscle preparation interacting in real time with an in silico model of a legged jumper to understand how changes in temperature affect the flow of energy in a system using a MA latch. We used the plantaris longus muscle-tendon unit (MTU) to power a virtual limb with changing MA and a mass being accelerated through a real-time feedback controller. We quantified the amount of energy stored in and recovered from elastic structures and the additional contribution of direct muscle work after unlatching. We found that temperature altered the duration of the energy loading and recovery phase of the in vitro/in silico experiments. We found that the early phase of loading was insensitive to changes in temperature. However, an increase in temperature did increase the rate of force development, which in turn allowed for increased energy storage in the second phase of loading. We also found that the contribution of direct muscle work after unlatching was substantial and increased significantly with temperature. Our results show that the thermal robustness achieved by an elastic mechanism depends strongly on the nature of the latch that mediates energy flow, and that the relative contribution of elastic and direct muscle energy likely shapes the thermal sensitivity of locomotor systems.

Reconstructing the transport cycle in the sugar porter superfamily using coevolution-powered machine learning.

Sugar porters (SPs) represent the largest group of secondary-active transporters. Some members, such as the glucose transporters (GLUTs), are well known for their role in maintaining blood glucose homeostasis in mammals, with their expression upregulated in many types of cancers. Because only a few sugar porter structures have been determined, mechanistic models have been constructed by piecing together structural states of distantly related proteins. Current GLUT transport models are predominantly descriptive and oversimplified. Here, we have combined coevolution analysis and comparative modeling, to predict structures of the entire sugar porter superfamily in each state of the transport cycle. We have analyzed the state-specific contacts inferred from coevolving residue pairs and shown how this information can be used to rapidly generate free-energy landscapes consistent with experimental estimates, as illustrated here for the mammalian fructose transporter GLUT5. By comparing many different sugar porter models and scrutinizing their sequence, we have been able to define the molecular determinants of the transport cycle, which are conserved throughout the sugar porter superfamily. We have also been able to highlight differences leading to the emergence of proton-coupling, validating, and extending the previously proposed latch mechanism. Our computational approach is transferable to any transporter, and to other protein families in general.

P62: A Unique case of Transcatheter aortic valve replacement dislodgement in the presence of a durable left ventricular assist device

Background: Transcatheter aortic valve replacement [TAVR] for severe pure aortic insufficiency [AI] in the presence of a durable left ventricular assist device [LVAD] is fraught with challenges. We report an interesting case of TAVR valve dislodgement by the LVAD that was treated with redeployment of another TAVR valve, and redo surgery for extraction of the intraventricular TAVR valve. Methods and Results: A 46-year-old man presented to our unit in cardiogenic shock [CS] and severe pulmonary hypertension [PH] of 72/45mmHg. He underwent placement of an Impella 5.5 [Abiomed, Danvers, MA] as a bridging strategy to treat his CS and PH while transplant candidacy was being assessed. However, he remained pulmonary hypertensive with a trans-pulmonary gradient 26mmHg and pulmonary vascular resistance 5.3 wood units, despite 14 days of impella 5.5 therapy combined with aggressive management with milrinone 0.25 mcg/kg/min and bumetanide infusion 1mg/hr. He therefore underwent implantation of heart mate 3 [HM3] LVAD [Abbott Laboratories, Chicago, IL] by a limited left thoracotomy in the 5th intercostal space and upper ‘inverse-T’ hemi-sternotomy into the fourth intercostal space. His postoperative course was complicated by requirement for 31mm percutaneous Protek Duo [LivaNova, London, UK] Right VAD [RVAD] for 32 days, and gastrointestinal bleeding requiring cessation of heparin therapy, which prompted formation of thrombus in the left coronary cusp of the aortic valve. Organization of this thrombus and consequent retraction of the left coronary leaflet led to severe AI and consequent CS, requiring inotropic support and discussion on optimal management strategy. He underwent TAVR with a 29mm Edwards Sapien 3 valve [Edwards Lifesciences, Irvine, CA] with 20% over-sizing, which got dislodged and migrated into the LV. Another 29mm Edwards Sapien 3 TAVR valve was successfully deployed. The patient was then placed on cardiopulmonary bypass via the femoral vessels, and the left thoracotomy was reopened. The LVAD was temporarily stopped, and the latch mechanism on the HM3 was opened. The HM3 was removed from the sewing cuff, and the TAVR valve was ‘fished-out’ from the cavity of the LV. The HM3 was reinserted and restarted after thorough de-airing through the outflow graft. The incisions were closed in a standard manner and the patient was discharged home on the 20th postoperative day. Conclusions: TAVR for severe AI in the presence of a durable LVAD is fraught with challenges due to the constant suction action of the LVAD, and the absence of calcium in the native annulus to anchor the prosthesis. Our case highlights the feasibility of extricating a dislodged TAVR valve through simple redo-surgery. With this approach, we managed to avoid a more conventional redo procedure involving administration of cardioplegia for a surgical AVR or for extricating the prosthesis, with its inherent risk of right ventricular failure requiring RVAD. Figure showing dislodged TAVR on the left and redeployment on the right

Embodied latch mechanism of the mandible to power at ultra-high speed in the trap-jaw ant Odontomachus kuroiwae.

Rapid movements of limbs and appendages, faster than those produced by simple muscle contraction alone, are generated through mechanical networks consisting of springs and latches. The latch plays a central role in these spring-loaded mechanisms, but the structural details of the latch are not always known. The mandibles of the trap-jaw ant Odontomachus kuroiwae closes the mandible extremely quickly to capture prey or to perform mandible-powered defensive jumps to avoid potential threats. The jump is mediated by a mechanical spring and latch system embodied in the mandible. An ant can strike the tip of the mandible onto the surface of an obstacle (prey, predator or ground) in order to bounce its body away from potential threats. The angular velocity of the closing mandible was 2.3×104rads-1 (1.3×106degs-1). Latching of the joint is a key mechanism to aid the storage of energy required to power the ballistic movements of the mandibles. We have identified the fine structure of two latch systems on the mandible forming a 'ball joint' using an X-ray micro-computational tomography system (X-ray micro-CT) and X-ray live imaging with a synchrotron. Here, we describe the surface of the inner section of the socket and a projection on the lip of the ball. The X-ray live imaging and movements of the 3D model show that the ball with a detent ridge slipped into a socket and over the socket ridge before snapping back at the groove edge. Our results give insight into the complex spring-latch systems that underpin ultra-fast movements in biological systems.

Dynamic Analysis of Bidirectional Solar Arrays with Flexible Panels and Clearance Joints

The dynamic characteristics of a two-step deployable bidirectional solar array system with flexible panels and clearance joints are studied in this paper. Driving mechanisms, closed cable loop configurations, and latch mechanisms are considered in this system where normal contact force is established using a nonlinear spring damping model and the friction effect is determined by a modified Coulomb friction model. With the simulation strategy of activating different constraint states and applying latch torques, the multiple deployment and locking processes of the system are implemented. The results indicate that the second locking causes obvious vibration on the dynamic responses of the yoke and main panels and leads to a complex bidirectional vibration of the main panel connected to the side clearance joints. The equivalent suspension damping property produced by the coupling of the flexibility and clearances can reduce the vibration of the deployable components. Moreover, the attitude and orbital motion results reveal the effect of different deployment methods of the system on the spacecraft attitude. Finally, the trajectories of journal centers and contact forces are analyzed to indicate the foundation of the dynamic behavior of the system.

Self-Aligning Rotational Latching Mechanisms: Optimal Geometry for Mechanical Robustness

Abstract In concurrent work, we introduced a novel robotic package delivery system latching intelligent modular mobility system (LIMMS). Each LIMMS end effector requires a small, lightweight latching mechanism for pre-manufactured containers, such as cardboard boxes. In order to effectively process a high volume of packages, aligning the latching mechanism quickly and reliably is critical. Instead of depending on highly accurate controllers for alignment, we propose a novel self-aligning rotational mechanism to increase the system’s tolerance to misalignment. The radial latching design consists of evenly spaced blades that rotate into slots cut into the box. When misaligned, the blades contact the edges of the engagement slots, generating a self-correcting force that passively centers the blades with the slot pattern. This paper introduces a mathematical framework with closed form expressions to quantify error tolerance for these mechanisms. Through our mathematical and optimization analyses, it is shown that a two-blade design can tolerate a maximum misalignment of three times the radius to the blade tips, much larger than commonly used designs with three or more blade-like contacts. Our approach can be generalized for a class of rotational latching mechanisms with any number of blades. Utilizing this theory, a design process is laid out for developing an optimal self-aligning rotational latching mechanism given desired parameters and task constraints. With this methodology, we designed, manufactured, and verified the effectiveness of both two-blade and three-blade self-aligning in practical experiments.

A Novel Design and Development of Mortice Tubular Deadbolt Latch Mechanism

Abstract: In order to protect individuals or secure items in a respected location or region, locks are devices that keep the door, gate, or drawer stable in its position when it is closed. These are the typical standard sorts that have been in use for a while; an innovative idea has been proposed to replace them with smart mechanisms. In order to lower the price and the size of the existing type by increasing the ease of operation and security. In this project, a brand-new latch mechanism is suggested as an alternate for primordial ones. Using a solenoid, the deadbolt will lock automatically when the door is closed, either from inside or outside; a keyless way can be used to open it from inside, and a key can be used to unlock it from outside. In comparison to previous mortice locks on the market, it only requires a small vent on a door, whereas the ubiquitous one requires a large vent. This may weaken the door and affect the door’s life. The installation is also a swift process, as it requires only a small vent and comes ready to install. This uses a constant power source and can be installed in any type of door. It also has a battery backup for the specified amount of time. Using Ansys, the lock's stress is computed and compared to the existing one

Plastic design and strength on automotive hard trims doghouse

Trims are the plastic parts installed on the inside and outside of a car. Interior trims are typically used to give the interior of a vehicle an aesthetic appearance.There are various types of trims used in automobiles. The door's inner mechanisms and the vehicle's interior are connected by the door panel, as are the passengers inside the car and the door. They must adhere to a number of design requirements in terms of functionality, appearance, and safety. They should also maintain the dashboard's material theme while hiding complex electrical and mechanical parts that control the vehicle's locks, windows, and other features. From a straightforward latch and winding mechanism in two parts, the door panel has developed into a more complex enclosure. Currently, doors have an inner full-width panel with speakers, electronic windows, and a central locking system. These panels typically have a foamed core that is covered in either plastic or textiles. Trim manufacturing requires a lot of essential plastic material properties, such as restraining the passengers from the sharp edges and corner points of the BIW parts and underlying components.

Probing mechanotransduction pathways through visualization and control of vinculin conformation.

Vinculin is important in multiple contexts where cells must measure and respond to mechanical force. It acts via a conformational latch mechanism where stretching produces an open conformation that enables binding to downstream effectors. We are specifically studying how cells use vinculin-containing structures called podosomes to probe the rigidity of potential targets during phagocytosis, and how cancer cells navigate between tumors and the vasculature by sensing the rigidity of aligned collagen using focal adhesions. Podosomes oscillate like pistons against phagocytic targets, with frequency dependent on target stiffness. Metastatic cells use vinculin-containing focal adhesions to monitor and respond to the rigidity of collagen fibers. In each case it is difficult to probe hypotheses coupling mechanical changes in vinculin to downstream signaling because interactions are transient and localized. We are therefore developing vinculin analogs for use in living cells to 1) report vinculin conformational state, and 2) control vinculin activity with light.

Investigation on a new type of latching mechanism on the satellite-rocket docking system and locking dynamic analysis

To meet the in-orbit maintenance requirements of malfunctioning satellites and maintenance satellites rigid connections, a new type of latching mechanism based on satellite-rocket docking ring is proposed, which has light weight, good structural stiffness, simple motion and locking mechanism, simple control logic, high reliability and large range of docking ring size adaptation. A multi-body dynamic model of the docking ring latch mechanism, malfunctioning satellite and maintenance satellite were established, the maximum locking force and maximum friction of the latch mechanism and the maximum stress of the latching joint and crank of the direct force component were analyzed, and the change of locking force and friction under the three typical in-orbit maneuvering conditions were studied. The results show that: the maximum locking force and maximum friction of the latch mechanism on the docking ring is 1300N and 320N, respectively, stable locking force and friction are 300N and 80N, respectively, the maximum stress occurs on connecting rod which is 865 MPa; In-orbit maneuvering has little effect on the locking force and friction of the docking ring latch mechanism, and the docking ring latch mechanism can always lock the malfunctioning satellite steadily and reliably.

Carbon sequestration and the enzymic latch mechanism in red, black and white mangrove soils of Florida USA

Carbon sequestration and the enzymic latch mechanism in red, black and white mangrove soils of Florida USA

Carbon sequestration and the enzymic latch mechanism in red, black and white mangrove soils of Florida USA

Mangrove swamps are important habitat types providing vital ecological services, such as protection of coastlines from erosion and extreme weather conditions including hurricanes, recycling of nutrients and sequestration of carbon. Mangrove swamps support a wide range of biodiversity, improve water quality, provide fish for local communities. They are also used as a source of wood fuel, medication as well as for harvesting honey for the local population. Soil samples for laboratory analyses were collected from red (Rhizophora mangle), black (Avicennia germinans) and white (Laguncularia racemose) mangroves in Florida, USA to determine the biogeochemistry processes. Results of analyses indicated that the red mangrove soil is the most efficient for carbon sequestration. It had the lowest phenol oxidase activity (206.15 nmol dicq g-1 h-1), highest phenolic concentration (262.33 µg g-1) and lowest hydrolase enzyme activity (β-glucosidase) (3.04 nmol g-1 min-1) and, as a result, the highest concentration of soil organic matter (SOM) (57.9%). It is believed that the high soil water content (84.2%).) of the red mangrove, due to its proximity to the sea, is a key driver of these observations. The 'enzymic latch' mechanism appears to be prevalent in the red mangrove soil, in particular, allowing these ecosystems to be effective at carbon storage hence, could serve as an important natural tool in mitigating the effect of climate change. Preservation and conservation of mangrove swamps is vital in balancing the effect of global warming.

COMPUTER PROCEDURE FOR SELECTING PARAMETERS OF THE PERIPHERAL DOCKING ASSEMBLY LATCH MECHANISM

When developing the country’s made peripheral docking assembly consistent with the International Docking System Standard a task arose concerning reduction of dimensions of the latch mechanisms that ensure the capture. The article describes the mode of operation of these mechanisms. Proposed is a procedure which makes it possible to choose such a layout of their joints in which the links are inside a given area during operation. A uniform LPτ-sequence is used to form various options of the joints layout. A criterion of maximum loads acting on the links is described. It is shown that the dimensions of the existing latch mechanism can be decreased only with an increase of the load-carrying capability of the links. The proposed procedure is part of a software tool computerizing the design of a new latch mechanism. Key words: spacecraft docking, peripheral docking assembly, latch mechanism, capture, LPτ-sequence.

Design of a Four-Bar Latch Mechanism and a Shear-Based Rotary Viscous Damper for Single-Axis Prosthetic Knees

Abstract With over 30 million people worldwide requiring assistive devices, there is a great need for low-cost and high-performance prosthetic technologies that can enable kinematics close to able-bodied gait. Low-income users of prosthetic knees in the developing world repeatedly report the need for n inconspicuous gait to mitigate the severe socioeconomic discrimination associated with disability. However, passive prosthetic knees designed for these users have primarily focused on stability and affordability, often at the cost of the high biomechanical performance that is required to replicate able-bodied kinematics. In this study, we present the design and preliminary testing of two distinct mechanism modules that are novel for passive prosthetic knee applications: the stability module and the damping module. These mechanisms are designed to enable users of single-axis, passive prosthetic knees to walk with close to able-bodied kinematics on level-ground, specifically during the transition from the stance phase to the swing phase of the gait cycle. The stability module was implemented with a latch mounted on a virtual axis of a four-bar linkage, which can be engaged during early stance for stability and disengaged during late stance to initiate knee flexion. The damping module was implemented with a concentric stack of stationary and rotating pairs of plates that shear thin films of high-viscosity silicone oil. The goal of the resulting first-order damping torque was to achieve smooth flexion of the prosthetic knee within the able-bodied gait range (64 ± 6 deg). For preliminary user-centric validation, a prototype prosthetic knee with the stability module and two different dampers (with varying damping coefficients) was tested on a single subject with above-knee amputation in India. The stability module enabled smooth transition from stance to swing with timely initiation of knee flexion. The dampers also performed satisfactorily, as the increase in the damping coefficient was found to decrease the peak knee flexion angle during swing. The applications of the mechanisms presented in this article could significantly improve the kinematic performance of low-cost, passive prosthetic knees.

Oxidases and hydrolases mediate soil organic matter accumulation in chernozem of northeastern China

An enzymatic latch on carbon store in peatlands or desert soils has been verified but has rarely been examined in a cultivated field with a high pH and a high calcium carbonate content. Soil organic matter (SOM) contents of chernozem have decreased over the last few decades in northeast China. However, the enzymatic mechanism of SOM loss in this region remains unclear. An experiment was conducted to investigate the effects of soil oxidases and hydrolases on SOM, the correlations between soil oxidases and hydrolases, and the relationships between soil microbial community and related soil enzymes with 40 soil samples from different cultivated fields in Lishu County, northeastern China. The results showed that SOM increased significantly over the pH range of 5.0–7.0, and decreased sharply in the range of 7.0–8.0. Soil oxidases (peroxidase and total oxidases) activities showed significant and negative correlations with SOM content but positive correlations with hydrolases (β-glucosidase, β-xylosidase and total hydrolases) activities. The SOM content was significantly and negatively correlated with α-glucosidase, β-glucosidase, cellobiohydrolase, β-xylosidase, and total hydrolases activities. Results of redundancy analysis indicated that all soil hydrolases activities had positive relationships with bacteria i15:0, 16:3 ω6c and 16:0. Peroxidase and total oxidases activities were positively associated with bacteria cy17:0 ω7c, 15:0 DMA, i16:0, 18:0, i17:0, 14:0, 15:0 and actinomycetes 17:0 10-methyl, 18:0 10-methyl, while phenol oxidase activity was positively associated with bacteria i17:1 ω9c, 17:1 ω8c, i14:0 and fungi 18:1 ω9c. These findings confirmed the enzymatic latch mechanism of SOM accumulation in this test chernozem, which means that oxidases relieve the inhibition of hydrolases, resulting in SOM hydrolysis by higher hydrolases activities.

Molecular basis for the disruption of Keap1\u2013Nrf2 interaction via Hinge & Latch mechanism

The Keap1-Nrf2 system is central for mammalian cytoprotection against various stresses and a drug target for disease prevention and treatment. One model for the molecular mechanisms leading to Nrf2 activation is the Hinge-Latch model, where the DLGex-binding motif of Nrf2 dissociates from Keap1 as a latch, while the ETGE motif remains attached to Keap1 as a hinge. To overcome the technical difficulties in examining the binding status of the two motifs during protein-protein interaction (PPI) simultaneously, we utilized NMR spectroscopy titration experiments. Our results revealed that latch dissociation is triggered by low-molecular-weight Keap1-Nrf2 PPI inhibitors and occurs during p62-mediated Nrf2 activation, but not by electrophilic Nrf2 inducers. This study demonstrates that Keap1 utilizes a unique Hinge-Latch mechanism for Nrf2 activation upon challenge by non-electrophilic PPI-inhibiting stimuli, and provides critical insight for the pharmacological development of next-generation Nrf2 activators targeting the Keap1-Nrf2 PPI.

Structures and General Transport Mechanisms by the Major Facilitator Superfamily (MFS).

The major facilitator superfamily (MFS) is the largest known superfamily of secondary active transporters. MFS transporters are responsible for transporting a broad spectrum of substrates, either down their concentration gradient or uphill using the energy stored in the electrochemical gradients. Over the last 10 years, more than a hundred different MFS transporter structures covering close to 40 members have provided an atomic framework for piecing together the molecular basis of their transport cycles. Here, we summarize the remarkable promiscuity of MFS members in terms of substrate recognition and proton coupling as well as the intricate gating mechanisms undergone in achieving substrate translocation. We outline studies that show how residues far from the substrate binding site can be just as important for fine-tuning substrate recognition and specificity as those residues directly coordinating the substrate, and how a number of MFS transporters have evolved to form unique complexes with chaperone and signaling functions. Through a deeper mechanistic description of glucose (GLUT) transporters and multidrug resistance (MDR) antiporters, we outline novel refinements to the rocker-switch alternating-access model, such as a latch mechanism for proton-coupled monosaccharide transport. We emphasize that a full understanding of transport requires an elucidation of MFS transporter dynamics, energy landscapes, and the determination of how rate transitions are modulated by lipids.