A controllable dual-catapult system inspired by the biomechanics of the dragonfly larvae’s predatory strike

2021 ◽  
Vol 6 (50) ◽  
pp. eabc8170
Author(s):  
Sebastian Büsse ◽  
Alexander Koehnsen ◽  
Hamed Rajabi ◽  
Stanislav N. Gorb
Keyword(s):  
Driving Force ◽  
Kinematic Chain ◽  
Current Theory ◽  
Hydraulic Pressure ◽  
Proof Of Concept ◽  
Ballistic Movement ◽  
Predatory Strike ◽  
Thrust Vector ◽  
Extension Direction ◽  
Ambush Predators

The biomechanics underlying the predatory strike of dragonfly larvae is not yet understood. Dragonfly larvae are aquatic ambush predators, capturing their prey with a strongly modified extensible mouthpart. The current theory of hydraulic pressure being the driving force of the predatory strike can be refuted by our manipulation experiments and reinterpretation of former studies. Here, we report evidence for an independently loaded synchronized dual-catapult system. To power the ballistic movement of a single specialized mouthpart, two independently loaded springs simultaneously release and actuate two separate joints in a kinematic chain. Energy for the movement is stored by straining an elastic structure at each joint and, possibly, the surrounding cuticle, which is preloaded by muscle contraction. As a proof of concept, we developed a bioinspired robotic model resembling the morphology and functional principle of the extensible mouthpart. Understanding the biomechanics of the independently loaded synchronized dual-catapult system found in dragonfly larvae can be used to control the extension direction and, thereby, thrust vector of a power-modulated robotic system.

scholarly journals Hunting with catapults: the predatory strike of the dragonfly larva

2020 ◽  
Author(s):  
Sebastian Büsse ◽  
Alexander Koehnsen ◽  
Hamed Rajabi ◽  
Stanislav N. Gorb
Keyword(s):  
Power Output ◽  
Driving Force ◽  
Robotic Arm ◽  
Hydraulic Pressure ◽  
Proof Of Concept ◽  
Ballistic Movement ◽  
Present Evidence ◽  
Current Opinion ◽  
Predatory Strike ◽  
Dragonfly Larva

AbstractDragonfly larvae capture their prey with a strongly modified -extensible- mouthpart using a biomechanically unique but not yet understood mechanism. The current opinion of hydraulic pressure being the driving force of the predatory strike can be refuted by our manipulation experiments and reinterpretation of former studies. On this fact, we present evidence for a synchronized dual-catapult system powered by two spring-loaded catapults. The power output of the system exceeds generally the maximum power achievable by musculature. Energy for the movement is stored by straining a resilin-containing structure at each joint and possibly the surrounding cuticle which is preloaded by muscle contraction. To achieve the precise timing required to catch fast-moving prey, accessory structures are used to lock and actively trigger the system, ensuring the synchronisation of both catapults. As a proof of concept, we developed a bio-inspired robotic arm resembling the morphology and functional principle of the extensible mouthpart. Our study elucidates the predatory strike of dragonfly larvae by proposing a novel mechanism, where two synchronized catapults power the ballistic movement of prey capturing in dragonfly larvae – a so-called synchronized dual-catapult system. Understanding this complex biomechanical system may further our understanding in related fields of bio inspired robotics and biomimetics.One Sentence SummaryThe synchronized dual-catapult, a biomechanically novel mechanism for the ballistic movement of prey capturing in dragonfly larvae

scholarly journals Water Transport in Unsaturated Cracked Concrete under Pressure

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Yuanzhu Zhang ◽  
Siming Zhang ◽  
Gang Wei ◽  
Xinjiang Wei ◽  
Liqiao Jin ◽  
...  
Keyword(s):  
Water Transport ◽  
Driving Force ◽  
Crack Width ◽  
Water Pressure ◽  
Theoretical Models ◽  
Double Porosity ◽  
Hydraulic Pressure ◽  
Pressure Potential ◽  
Cracked Concrete ◽  
Concrete Permeability

In order to analyze the process of hydraulic water infiltrating cracked concrete of underwater tunnels, the equation of water transport in unsaturated cracked concrete under pressure was proposed according to the double-porosity medium model. Penetration tests on prefabricated cracked concrete blocks were conducted, and then the influence of hydraulic pressure, initial saturation, and crack width on water transport was studied. The results show that the larger the water pressure, the lower the initial saturation, and the wider the crack width, then the greater the penetration depth, which can be reasonably explained according to water motion theoretical models in this study. Moreover, the TOUGH2 software was used to simulate the change and distribution of saturation, driving potential, and water velocity of unsaturated cracked concrete, which further proved the experimental results and theoretical analysis. It reflects that both pressure potential and matric potential are the driving force of water transport in underwater cracked concrete, and the driving force will be converted with the change of concrete saturation. In addition, crack width is positively correlated with concrete permeability.

Optimization of direct-osmosis–high-salinity cleaning for reverse osmosis fouling control in water reuse

2010 ◽  
Vol 10 (5) ◽  
pp. 800-805 ◽  
Author(s):  
Jian-Jun Qin ◽  
Maung Htun Oo ◽  
Kiran A. Kekre ◽  
Harry Seah
Keyword(s):  
Membrane Fouling ◽  
Driving Force ◽  
Water Reuse ◽  
Systematic Approach ◽  
High Salinity ◽  
Proof Of Concept ◽  
Salt Consumption ◽  
Fouling Control ◽  
Injection Duration ◽  
Ro Membrane

This paper focuses on the systematic approach adopted towards optimizing the salt consumption when using direct-osmosis–high-salinity (DO-HS) cleaning method for RO membranes in water reuse application. Trials were carried out on a pilot RO system with a capacity of 50 m3/day. Initially, proof of concept for the DO-HS method in water reuse application was established wherein the profile of osmotic driving force for DO backwash, DO backwash flow during HS injection, removal of foulants with DO-HS treatment and lower RO fouling rate with the DO-HS method were demonstrated. 6 months of trials further demonstrated that RO membrane fouling rate and CIP frequency could be significantly reduced with the DO-HS method and there was no impact on the performance of RO membranes. Further trials were carried out focusing of salt requirements and it was found that salt injection duration could be reduced by 68% while the 48-h interval of salt injection was not recommended. Currently, the salt consumption has been reduced from the initial at 0.5 ton to the current at 0.16 ton as per 10,000 m3/day production. The study is ongoing to achieve the target of 0.05 ton for ease of operation.

Phytoclimatic mapping of exoplanets

2019 ◽  
Vol 19 (1) ◽  
pp. 68-77 ◽  
Author(s):  
David S. Stevenson
Keyword(s):  
Driving Force ◽  
Climate Models ◽  
Climate Model ◽  
Mathematical Framework ◽  
Proof Of Concept ◽  
Biological Potential ◽  
Model Components ◽  
Frictional Coefficients ◽  
The Impact ◽  
Host Complex

AbstractThe concept of exoplanetary habitability is evolving. The driving force is a desire to define the biological potential of planets and identify which can host complex and possibly intelligent life. To assess this in a meaningful manner, climate models need to be applied to realistic surfaces. However, the vast majority of climate models are developed using generic aquaplanet, or swamp planet, scenarios that provide uniform, surface frictional coefficients. However, aside from planets with largely uniform oceans, these models are not obviously useful when it comes to understanding the impact of climate on biodiversity. Here, we show that contrary to expectation, the aquaplanet models can be directly applied to planets with a variety of land areas, with little need for modification. Using this premise, this paper provides a simple mathematical framework that may be applied to more complex planetary surfaces and identifies the majority of the climate-model components that are needed to accurately determine the biological potential of habitable exoplanets. As a proof-of-concept, an available climate model for Proxima b is used to determine its biological potential, given a suitable atmosphere.

Transport of molecules across renal glomerular capillaries

1976 ◽  
Vol 56 (3) ◽  
pp. 502-534 ◽  
Author(s):  
B. M. Brenner ◽  
C. Baylis ◽  
W. M. Deen
Keyword(s):  
Driving Force ◽  
Molecular Size ◽  
Colloid Osmotic Pressure ◽  
Capillary Network ◽  
Hydraulic Pressure ◽  
Glomerular Injury ◽  
Glomerular Capillary ◽  
Direct Measurements ◽  
Transport Of Macromolecules ◽  
Glomerular Capillaries

Direct measurements of the pressures and flows governing the formation of glomerular ultrafiltrate have been made possible in recent years by virtue of 1) the discovery of rats and monkeys possessing glomerular capillaries on the renal cortical surface, accessible to micropuncture, and 2) technological advances that permit measurement of intracapillary hydraulic pressure and assessment of the change in colloid osmotic pressure along the glomerular capillary network. Based on these direct measurements, evidence has been obtained to indicate that glomerular capillary hydraulic pressure and hence the net driving force for ultrafiltration are lower than previously believed. By the efferent end of the glomerular capillary network, net filtration of fluid ceases, owing to a reduction in the net driving force to zero. Evidence in the rat indicates that the process of ultrafiltration is highly dependent on glomerular plasma flow rate. Studies in rats with surface glomeruli have also made possible an assessment of the factors that govern the transport of macromolecules across the highly specialized capillary network. In addition to molecular size, transcapillary movement of macromolecules is influenced by the glomerular filtration rate, since total transport reflects the combined contributions of convection as well as diffusion. Molecular charge has also been found to be an important determinant of the transport of macromolecules, very likely contributing to the marked restriction to the transcapillary movement of albumin. This electrostatic restriction to the transport of polyanions such as albumin, by some fixed, negatively charged component(s) of the glomerular capillary wall, is markedly reduced in primary glomerular injury. Evidence indicates that glomerular injury results in loss of these fixed negative charges from the capillary walls, providing an attractive explanation for the enhanced filtration of albumin, and hence the proteinuria, observed in a variety of glomerulopathic states.

scholarly journals Key experimental evidence of chromosomal DNA transfer among selected tuberculosis-causing mycobacteria

2016 ◽  
Vol 113 (35) ◽  
pp. 9876-9881 ◽  
Author(s):  
Eva C. Boritsch ◽  
Varun Khanna ◽  
Alexandre Pawlik ◽  
Nadine Honoré ◽  
Victor H. Navas ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Driving Force ◽  
Risk Evaluation ◽  
Size Range ◽  
Dna Transfer ◽  
Whole Genome ◽  
Proof Of Concept ◽  
Chromosomal Dna ◽  
Transfer Frequency ◽  
The Impact

Horizontal gene transfer (HGT) is a major driving force of bacterial diversification and evolution. For tuberculosis-causing mycobacteria, the impact of HGT in the emergence and distribution of dominant lineages remains a matter of debate. Here, by using fluorescence-assisted mating assays and whole genome sequencing, we present unique experimental evidence of chromosomal DNA transfer between tubercle bacilli of the early-branching Mycobacterium canettii clade. We found that the obtained recombinants had received multiple donor-derived DNA fragments in the size range of 100 bp to 118 kbp, fragments large enough to contain whole operons. Although the transfer frequency between M. canettii strains was low and no transfer could be observed among classical Mycobacterium tuberculosis complex (MTBC) strains, our study provides the proof of concept for genetic exchange in tubercle bacilli. This outstanding, now experimentally validated phenomenon presumably played a key role in the early evolution of the MTBC toward pathogenicity. Moreover, our findings also provide important information for the risk evaluation of potential transfer of drug resistance and fitness mutations among clinically relevant mycobacterial strains.

A Multi-Axis Deep Drawing Servo Press With Non-Overconstrained Architecture

2014 ◽  
Author(s):  
Francesco Meoni ◽  
Adrian Lutey ◽  
Alessandro Fortunato ◽  
Marco Carricato
Keyword(s):  
Kinematic Chain ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Ball Screw ◽  
Proof Of Concept ◽  
Innovative Method ◽  
Servo Press ◽  
Under Construction ◽  
Servo Axis ◽  
Kinematic Mechanism

Servo actuated presses can provide maximum pressing force at any slide position in the same manner that hydraulic presses do, while offering several benefits in terms of precision, energy conversion efficiency and simplicity due to their lack of hydraulic circuitry and oil. Several press builders have developed electric-spindle actuated presses; however, issues relating to multi-axis architecture have been neglected. The present study proposes an innovative method of avoiding overconstrained architecture by implementing a kinematic mechanism that connects multiple servo axes to one slide. Servo axis design is developed by creating a dynamic model of a kinematic chain composed of a servo-motor, gearbox reducer and ball screw transmission. A study of a biaxial industrial servo press prototype with non-overconstrained architecture, currently under construction, is presented as proof of concept. It is shown that such a non-overconstrained multi-axis press can be constructed from commercially available components, achieving high energy efficiency at high load with relatively simple construction.

In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

1992 ◽  
Vol 50 (1) ◽  
pp. 256-257
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortright
Keyword(s):  
Layered Structure ◽  
Driving Force ◽  
High Energy ◽  
Superior Performance ◽  
In Situ Tem ◽  
Rayleigh Instability ◽  
Practical Applications ◽  
Transmission Electron ◽  
Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

The nucleation of cavities at grain boundaries

1987 ◽  
Vol 45 ◽  
pp. 288-291
Author(s):  
P. J. Goodhew
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Grain Boundaries ◽  
Radiation Damage ◽  
Impurity Concentration ◽  
Driving Force ◽  
Nucleation And Growth ◽  
Phase Boundaries ◽  
Cavity Nucleation ◽  
Spherical Bubble

Cavity nucleation and growth at grain and phase boundaries is of concern because it can lead to failure during creep and can lead to embrittlement as a result of radiation damage. Two major types of cavity are usually distinguished: The term bubble is applied to a cavity which contains gas at a pressure which is at least sufficient to support the surface tension (2g/r for a spherical bubble of radius r and surface energy g). The term void is generally applied to any cavity which contains less gas than this, but is not necessarily empty of gas. A void would therefore tend to shrink in the absence of any imposed driving force for growth, whereas a bubble would be stable or would tend to grow. It is widely considered that cavity nucleation always requires the presence of one or more gas atoms. However since it is extremely difficult to prepare experimental materials with a gas impurity concentration lower than their eventual cavity concentration there is little to be gained by debating this point.

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