Ratchet Mechanism Research Articles

Trade fetishism and the trade justice ratchet: between token and substantive change in NAFTA 2.0

ABSTRACT Countless socially responsible trade initiatives have emerged in recent years offering an uncertain mixture of token and substantive changes. After decades of battles over free trade, this marks a significant shift, challenging established debates over free versus regulated markets by promoting labour, gender, human, and environmental rights through trade agreements. This reorientation contains complex contradictions, with trade justice groups conceding to the popularity of trade while simultaneously insisting on a new vision of what trade is ‘about.’ Drawing on the idea of trade fetishism, this article argues that the desire for trade involves not only its material motivations, but its seductive content as a fetishised object of global capital, offering the fantasy of ‘trade’ as a symbolic source of pleasure. Through the case of the new NAFTA 2.0, it points to the relevance of trade politics that aspires not to overcome trade fetishism, but, as Lucas Pohl (2022) suggests, to ‘get with’ it. Through a trade justice ratchet mechanism, advocates have pushed for unanticipated changes, while also ceding to the limitations of the current order. The outcome is a process of contesting the symbolic content of what trade is and is not about, with significant material and policy implications.

New Nitinol-based Thermomechanically Adjustable IOL Technology.

To evaluate the feasibility of new adjustable intraocular lens (IOL) technology. The foldable adjustable IOL consists of a nitinol mechanism placed in a haptic-optic cradle. Heating actuators on the nitinol mechanism with a continuous green laser achieve controlled movement of the mechanism and optic. Activation occurs in controlled steps: rotation in 1-degree steps over 360 degrees, and anterior posterior movement in 0.25-diopter (D) steps with a range of +1.50 D. The IOL was tested in vitro and in vivo in a rabbit eye. Foldability and unfolding were demonstrated through a 2.6-mm cartridge. The adjustable lens mechanism was successfully tested in vitro and in vivo. Activation resulted in a change in optic position relative to the haptics and the capsular bag. Activation of the lever and ratchet mechanism showed radial advancement of the IOL clockwise and counterclockwise. In vivo rotatory movement was achieved after activation by the argon laser at 1 week after implantation. Anterior to posterior movement was accomplished by activating the circular spring actuator mechanism in the laboratory model. Uneventful folding and unfolding were performed. A new adjustable IOL with a mechanism that responds in measured steps had been shown to move as planned after activation by argon laser. This was successful in the laboratory in both radial and anterior posterior movement. The radial movement was also proven in vivo in an animal model. Further refinement of the prototype is currently being undertaken. [J Refract Surg. 2023;39(10):662-667.].

Nascent adhesions shorten the period of lamellipodium protrusion through the Brownian ratchet mechanism.

Directional cell migration is driven by the conversion of oscillating edge motion into lasting periods of leading edge protrusion. Actin polymerization against the membrane and adhesions control edge motion, but the exact mechanisms that determine protrusion period remain elusive. We addressed this by developing a computational model in which polymerization of actin filaments against a deformable membrane and variable adhesion dynamics support edge motion. Consistent with previous reports, our model showed that actin polymerization and adhesion lifetime power protrusion velocity. However, increasing adhesion lifetime decreased the protrusion period. Measurements of adhesion lifetime and edge motion in migrating cells confirmed that adhesion lifetime is associated with and promotes protrusion velocity, but decreased duration. Our model showed that adhesions' control of protrusion persistence originates from the Brownian ratchet mechanism for actin filament polymerization. With longer adhesion lifetime or increased-adhesion density, the proportion of actin filaments tethered to the substrate increased, maintaining filaments against the cell membrane. The reduced filament-membrane distance generated pushing force for high edge velocity, but limited further polymerization needed for protrusion duration. We propose a mechanism for cell edge protrusion in which adhesion strength regulates actin filament polymerization to control the periods of leading edge protrusion.

Autonomous ratcheting by stochastic resetting.

We propose a generalization of the stochastic resetting mechanism for a Brownian particle diffusing in a one-dimensional periodic potential: randomly in time, the particle gets reset at the bottom of the potential well it was in. Numerical simulations show that in mirror asymmetric potentials, stochastic resetting rectifies the particle's dynamics, with a maximum drift speed for an optimal average resetting time. Accordingly, an unbiased Brownian tracer diffusing on an asymmetric substrate can rectify its motion by adopting an adaptive stop-and-go strategy. Our proposed ratchet mechanism can model the directed autonomous motion of molecular motors and micro-organisms.

Biomechanical evaluation of an anatomical bone plate assembly for thin patella fracture fixation fabricated by titanium alloy 3D printing

This study established and evaluated the feasibility of a three-dimensional (3D)- printed titanium anatomical surface with adjustable thin bone plate assembly (AATBP) for patella fracture fixation. The AATBP was 1.6 mm in thickness and divided into a proximal plate (PP) with locking screw holes and a distal plate (DP) (0.4 mm in thickness) with compressive screw holes for assembly using a ratchet mechanism to adjust the total fixation height according to the patella size. Two pairs of hooks were designed on the proximal/distal edges to allow passage through the tendon to grip the fractured fragments. 3D printing combined with Computer Numerical Control (CNC) drilling was performed to manufacture the AATBP. Four-point bending and surface roughness tests were performed to evaluate the AATBP mechanical behavior. A cyclic (300 times) load test with 15-kg weights was adopted to compare the biomechanical stability between the AATBP and conventional tension band wiring (TBW) fixations. A parallel finite element (FE) analysis was achieved to understand the fracture gap and bone stress in the two different fixations on a transverse patella fracture. The result showed that the maximum AATBP manufacturing error was 3.75%. The average fracture gaps on the medial/lateral sides after cyclic loads were 2.38 ± 0.57 mm/2.30 ± 0.30 mm for TBW and 0.03 ± 0.01 mm/0.06 ± 0.03 mm for AATBP fixations. The same trend occurred in the FE simulation. This study confirmed that a complicated thin bone plate, including the anatomical surface, hooks, and ratchet with size-adjustable characteristics, can be fabricated using metal 3D printing with acceptable manufacturing error and reasonable anatomical surface/ thin bone plate assembly fitness. Biomechanical cyclic tests and FE simulation showed that the AATBP fixation is superior to the conventional TBW for patella transverse fractures.

ATP Drives the Formation of a Catalytic Hydrazone through an Energy Ratchet Mechanism.

An energy ratchet mechanism is exploited for the synthesis of a molecule. In the presence of adenosine triphosphate (ATP), hydrazone-bond formation between an aldehyde and hydrazide is accelerated and the composition at thermodynamic equilibrium is shifted towards the hydrazone. Enzymatic hydrolysis of ATP installs a kinetically stable state at which hydrazone is present at a higher concentration compared to the composition at thermodynamic equilibrium in the presence of the degradation products of ATP. It is shown that the kinetic state has an enhanced catalytic activity in the hydrolysis of an RNA-model compound.

ATP Drives the Formation of a Catalytic Hydrazone through an Energy Ratchet Mechanism

AbstractAn energy ratchet mechanism is exploited for the synthesis of a molecule. In the presence of adenosine triphosphate (ATP), hydrazone‐bond formation between an aldehyde and hydrazide is accelerated and the composition at thermodynamic equilibrium is shifted towards the hydrazone. Enzymatic hydrolysis of ATP installs a kinetically stable state, at which hydrazone is present at a higher concentration compared to the composition at thermodynamic equilibrium in the presence of the degradation products of ATP. It is shown that the kinetic state has an enhanced catalytic activity in the hydrolysis of an RNA‐model compound.

Structure and proposed DNA delivery mechanism of a marine roseophage

Tailed bacteriophages (order, Caudovirales) account for the majority of all phages. However, the long flexible tail of siphophages hinders comprehensive investigation of the mechanism of viral gene delivery. Here, we report the atomic capsid and in-situ structures of the tail machine of the marine siphophage, vB_DshS-R4C (R4C), which infects Roseobacter. The R4C virion, comprising 12 distinct structural protein components, has a unique five-fold vertex of the icosahedral capsid that allows genome delivery. The specific position and interaction pattern of the tail tube proteins determine the atypical long rigid tail of R4C, and further provide negative charge distribution within the tail tube. A ratchet mechanism assists in DNA transmission, which is initiated by an absorption device that structurally resembles the phage-like particle, RcGTA. Overall, these results provide in-depth knowledge into the intact structure and underlining DNA delivery mechanism for the ecologically important siphophages.

Theory of continental drift – causes of the motion. Historical review and observations

The theory of continental drift was published as early as 1912, but the mechanism and energy source of this motion has not yet been elucidated. In many cases, the generally accepted model of convection currents in the mantle contradicts observations such as the spreading of the ocean floor, the extension of rifts from triple points to all sides, the more or less unilateral movement of the lithosphere relative to the mantle, and others. In the first part of the double article, the evolution of views on this issue is shown, as well as measured data that document the important role of extraterrestrial energy sources for the movement of lithospheric plates in daily, annual and long-term climate cycles. In the second part of the two-part article, the entire theory of the mechanism of lithospheric plate motion will be outlined, based on the accumulation of incoming energy from the Sun in crustal rocks, the ratcheting mechanism, and the thermoelastic wave penetrating from the Earth's surface through the entire crust.

Output force and ratio of laparoscopic graspers: an evaluation of operating room ergonomics

"Laparoscopist's thumb," or thenar paresthesia, can result from prolonged or excessive grip force during laparoscopy, as can more general syndromes, such as carpal tunnel syndrome. This is particularly relevant in gynecology, where laparoscopic procedures are standard. Although this method of injury is well known, there is a paucity of data to guide surgeons in selecting more efficient, ergonomic instruments. This study compared the ratio of applied tissue force and required surgeon input in a sample of common ratcheting laparoscopic graspers in a small-handed surgeon, to provide potential metrics applicable to surgical ergonomics and surgeon instrument choice. Laparoscopic graspers with varied ratcheting mechanisms and tip shapes were evaluated. Brands included Snowden-Pencer, Covidien, Aesculap, and Ethicon. A Kocher was used as an open instrument comparison. Flexiforce A401 thin-film force sensors were used to measure applied forces. Data were collected and calibrated using an Arduino Uno microcontroller board with Arduino and MATLAB software. Single-handed, complete closure of each device's ratcheting mechanism was performed 3 times. The maximum required input force in Newtons was recorded and averaged. The average output force was measured with a bare sensor and the same sensor between 2 different thicknesses of LifeLike BioTissue. The most ergonomic ratcheting grasper for a small-handed surgeon was identified by the output ratio: the highest output force relative to the required surgeon input (the most force for the least amount of effort). The Kocher required an average input force of 33.66 N, with its highest output ratio of 3.46 (112 N output). The Covidien Endo Grasp was the most ergonomic, with an output ratio of 0.96 on the bare force sensor (31.4 N output). The Snowden-Pencer Wavy grasper was the least ergonomic, with an output ratio of 0.06 when applied to the bare force sensor (5.9 N output). All graspers except for the Endo Grasp had improving output ratios as tissue thickness and subsequent grasper contact area increased. Input force above that provided by the ratcheting mechanisms did not increase output force in a clinically relevant amount for any of the instruments evaluated. Laparoscopic graspers vary widely in their ability to provide reliable tissue force without requiring excessive input by the surgeon, and a point of diminishing returns often exists with increased surgeon input over designed ratcheting mechanisms. Output force and output ratio are potential quantitative measures of the efficiency of laparoscopic instruments. Providing users with this type of data could assist in optimizing instrument ergonomics.

Ratchet-Based Ion Pumps for Selective Ion Separations

A computational study shows that a flashing ratchet mechanism can separate equally charged ions based on diffusion coefficients and thus benefit the energy efficiency of water desalination and lithium extraction processes.

Investigating the bactria motion in an asymmetric ratchet channel.

Extracting network from noisy motion is an old subject that goes back to the work by M. V. Smoluchovski. A so called ratchet and pawl mechanism shows that, it is impossible to extract work from equilibrium noisy motion. In order to achieve network from noisy motion, one needs to simultaneously break the translation symmetry and also derive the system to out of equilibrium conditions.

Toward a Super-COP? Timing, Temporality, and Rethinking World Climate Governance

Toward a Super-COP? Timing, Temporality, and Rethinking World Climate Governance

A molecular information ratchet using a cone-shaped macrocycle

•Ratcheting mechanisms are essential to devise molecular motors •A new information ratchet was developed relying on the shape of a cyclodextrin macrocycle •A cyclodextrin rotaxane with three stations ends up in the kinetically favored position •Information ratchet with dual input: position and orientation of a cone-shaped macrocycle Molecular information ratchets are key to the construction of autonomous, chemically fueled small-molecule motors. We have developed a novel type of information ratchet sensitive to two types of information: the position and the orientation of a moving macrocycle on an axle. The originality of this system comes from the use of a cone-shaped chiral macrocycle, a cyclodextrin, that presents two distinct faces toward the reactive site and is responsible for the kinetic biases observed. The reaction of functional groups on the axle next to the larger rim was found to be faster than that next to the smaller rim. An additional advantage of the conical shape of cyclodextrins is the possibility of selective face functionalization, allowing the addition of a component that will be active in the kinetic bias, which will improve the ratchet efficiency, thus offering new possibilities in the design of molecular motors. Molecular information ratchets are key to the construction of autonomous, chemically fueled small-molecule motors. We have developed a novel type of information ratchet sensitive to two types of information: the position and the orientation of a moving macrocycle on an axle. The originality of this system comes from the use of a cone-shaped chiral macrocycle, a cyclodextrin, that presents two distinct faces toward the reactive site and is responsible for the kinetic biases observed. The reaction of functional groups on the axle next to the larger rim was found to be faster than that next to the smaller rim. An additional advantage of the conical shape of cyclodextrins is the possibility of selective face functionalization, allowing the addition of a component that will be active in the kinetic bias, which will improve the ratchet efficiency, thus offering new possibilities in the design of molecular motors.

A simplified analysis of the Feynman pallet and ratchet mechanism considering different forms of generated power

Abstract In this paper, we analyze the advanced Feynman’s mechanism from the well-known Feynman’s Lectures on Physics, under the maximum power output, maximum efficient power, and maximum power density criterion. Considering this mechanism like a thermal engine, and using a simplified model, the physical existence regions for these objective functions are shown. We also show their comparison for given values of a defined dimensionless parameter. The behavior for each case of both the general and the normalized forms of the objective functions is compared graphically and the existence of certain intervals of values for the variable parameter used, in which the relation of these objective functions change, is determined. Additionally, it is shown that as the numerical value of the mentioned variable parameter used approaches zero, the area of the region of physical existence of the objective functions is greater. The results of the mentioned comparison are discussed, and appropriate conclusions are included.

Cellular Competency during Development Alters Evolutionary Dynamics in an Artificial Embryogeny Model.

Biological genotypes do not code directly for phenotypes; developmental physiology is the control layer that separates genomes from capacities ascertained by selection. A key aspect is cellular competency, since cells are not passive materials but descendants of unicellular organisms with complex context-sensitive behavioral capabilities. To probe the effects of different degrees of cellular competency on evolutionary dynamics, we used an evolutionary simulation in the context of minimal artificial embryogeny. Virtual embryos consisted of a single axis of positional information values provided by cells' 'structural genes', operated upon by an evolutionary cycle in which embryos' fitness was proportional to monotonicity of the axial gradient. Evolutionary dynamics were evaluated in two modes: hardwired development (genotype directly encodes phenotype), and a more realistic mode in which cells interact prior to evaluation by the fitness function ("regulative" development). We find that even minimal ability of cells with to improve their position in the embryo results in better performance of the evolutionary search. Crucially, we observed that increasing the behavioral competency masks the raw fitness encoded by structural genes, with selection favoring improvements to its developmental problem-solving capacities over improvements to its structural genome. This suggests the existence of a powerful ratchet mechanism: evolution progressively becomes locked in to improvements in the intelligence of its agential substrate, with reduced pressure on the structural genome. This kind of feedback loop in which evolution increasingly puts more effort into the developmental software than perfecting the hardware explains the very puzzling divergence of genome from anatomy in species like planaria. In addition, it identifies a possible driver for scaling intelligence over evolutionary time, and suggests strategies for engineering novel systems in silico and in bioengineering.

Energy Storage Triboelectric Nanogenerator Based on Ratchet Mechanism for Random Ocean Energy Harvesting.

The instability of the ocean waves, such as intermittence, randomness, and irregularity, greatly affects the application of a triboelectric nanogenerator (TENG) in its aspects and leads to the irregularity and uncontrollability of its output performance. Hence, the energy storage TENG (ES-TENG) based on the ratchet mechanism is proposed in this work. The ES-TENG uses the ratchet mechanism to store the wave energy in the clockwork spring and then releases it in a centralized way to convert the wave energy into electric energy. When the ES-TENG adopts this method, the change of external excitation does not affect its output performance. Simultaneously, the shell of the ES-TENG is duck-shaped, which can better adapt to the wave environment. The peak power, open-circuit voltage, and short-circuit current of the ES-TENG are 6.2 mW, 495 V, and 19 μA, respectively. In the simulated wave experiment, the ES-TENG can successfully drive a temperature sensor. In summary, this work shows an economic, environmental friendly TENG that can adapt to the wave motion, and its output performance is not affected by wave instability, which has an important guiding significance for the further development and utilization of TENG in ocean energy.

VERTICAL VIBRATING MOVEABLE DEVICE

Modern industry is characterized by a high level of automation of technological operations in the production of any product. Thus, in order to save production space, as well as to organize the transportation of objects under the ceiling of the workshop, suspended transportation robotic systems are used. With their help, workpieces are supplied to workplaces, and finished parts to assembly positions, as well as loading and transfer of materials and finished products. First of all, it concerns the electronic and radio-electronic industry. There are a number of transport devices where the cargo flow can move both horizontally, at an angle to the horizon, and vertically. Transportation in the vertical plane can be carried out thanks to a working element such as a belt, rope, chain, combined element, auger, pipe, or a medium (air, water) or a phenomenon (electromagnetic field, vibrations). On the basis of the analysis of their designs and the patent search, it is possible to conclude that the working process of moving goods in the vertical plane, in connection with its wide variety of choosing a design solution, is the subject of scientific research, and the orientation of designers to the modernization of these means of movement, primarily with the aim increasing the efficiency of use, the energy efficiency coefficient and reducing the material consumption of equipment always remains an urgent task of mechanical engineering. The choice of such means depends, first of all, on its type, technological purpose, technical and economic indicators of production. All this indicates the need to deal with this issue, because even a slight improvement of these indicators gives a significant economic effect as a whole. In this work, as a development of alternative means of movement in suspended transport robotic systems, vibrating mobile devices, which can contain a cargo platform with a product or, for example, a simple manipulator, have become. We suggest you familiarize yourself with the results of the device's research in the forward and reverse direction of movement in the vertical plane. For the convenience of the study, a round profile (pipe) is taken as a monorail, on which a mobile vibrating device is strung. The design of the device can be quite diverse: in the form of elastic elements, brake, friction, overtaking, eccentric and ratchet mechanisms, etc. In this case, an elastic conical collet is used, which contacts the surface of the column. An effective means of implementing the given function is the use of an electromagnetic pad brake. The structure is built according to a two-mass scheme, which contains a working body, an electromagnetic drive and a locking mechanism. The effect of vibratory movement of the device along a vertical (rough) pipe is realized according to the asymmetry scheme of the first type under the action of longitudinal harmonic oscillations. Cyclic programming provides automatic execution of specified operations, stopping at loading and unloading positions, changing the direction of movement.

Autonomous Non-Equilibrium Self-Assembly and Molecular Movements Powered by Electrical Energy.

The ability to exploit energy autonomously is one of the hallmarks of life. Mastering such processes in artificial nanosystems can open technological opportunities. In the last decades, light- and chemically driven autonomous systems have been developed in relation to conformational motion and self-assembly, mostly in relation to molecular motors. In contrast, despite electrical energy being an attractive energy source to power nanosystems, its autonomous harnessing has received little attention. Herein we consider an operation mode that allows the autonomous exploitation of electrical energy by a self-assembling system. Threading and dethreading motions of a pseudorotaxane take place autonomously in solution, powered by the current flowing between the electrodes of a scanning electrochemical microscope. The underlying autonomous energy ratchet mechanism drives the self-assembly steps away from equilibrium with a higher energy efficiency compared to other autonomous systems. The strategy is general and might be extended to other redox-driven systems.

Autonomous Non‐Equilibrium Self‐Assembly and Molecular Movements Powered by Electrical Energy**

AbstractThe ability to exploit energy autonomously is one of the hallmarks of life. Mastering such processes in artificial nanosystems can open technological opportunities. In the last decades, light‐ and chemically driven autonomous systems have been developed in relation to conformational motion and self‐assembly, mostly in relation to molecular motors. In contrast, despite electrical energy being an attractive energy source to power nanosystems, its autonomous harnessing has received little attention. Herein we consider an operation mode that allows the autonomous exploitation of electrical energy by a self‐assembling system. Threading and dethreading motions of a pseudorotaxane take place autonomously in solution, powered by the current flowing between the electrodes of a scanning electrochemical microscope. The underlying autonomous energy ratchet mechanism drives the self‐assembly steps away from equilibrium with a higher energy efficiency compared to other autonomous systems. The strategy is general and might be extended to other redox‐driven systems.