scholarly journals Exploring the attachment of the Mediterranean medicinal leech ( Hirudo verbana ) to porous substrates

2020 ◽  
Vol 17 (168) ◽  
pp. 20200300
Author(s):  
Tim Kampowski ◽  
Lara-Louise Thiemann ◽  
Lukas Kürner ◽  
Thomas Speck ◽  
Simon Poppinga
Keyword(s):  
High Speed ◽  
Medicinal Leech ◽  
Mechanical Tests ◽  
Artificial Substrates ◽  
Hirudo Verbana ◽  
The Mediterranean ◽  
The Rich ◽  
Attachment Mechanism ◽  
Blood Meals ◽  
Porous Substrates

Haematophagous ectoparasites must ensure a reliable hold to their host during blood meals and, therefore, have evolved a broad spectrum of versatile and effective attachment mechanisms. The Mediterranean medicinal leech ( Hirudo verbana ), for example, uses suction on both smooth and textured air-tight substrates. However, preliminary studies showed that H. verbana is also capable of attaching itself to air-permeable substrates, where suction does not work. Using high-speed videography and mechanical tests, we comparatively investigated the attachment of H. verbana on both smooth and textured air-tight as well as on porous artificial substrates, also considering the influence of mucus on sucker surfaces. In general, the leech-specific locomotion cycle did not differ between the tested surfaces, and the leeches were able to reliably attach to both air-tight and porous substrates. From our results, we conclude that suction is presumably the primary attachment mechanism of H. verbana . However, secondary mechanisms such as mechanical interlocking with surface asperities and pores or capillary forces occurring at the interface between the mucus-covered suckers and the substratum are also employed. In any case, the rich repertoire of applicable attachment principles renders the organs of H. verbana functionally highly resilient.

scholarly journals Functional morphology of suction discs and attachment performance of the Mediterranean medicinal leech ( Hirudo verbana Carena)

2016 ◽  
Vol 13 (117) ◽  
pp. 20160096 ◽  
Author(s):  
Tim Kampowski ◽  
Laura Eberhard ◽  
Friederike Gallenmüller ◽  
Thomas Speck ◽  
Simon Poppinga
Keyword(s):  
Functional Morphology ◽  
High Speed ◽  
Substrate Surface ◽  
Surrounding Medium ◽  
Medicinal Leech ◽  
Force Measurements ◽  
High Speed Video ◽  
Hirudo Verbana ◽  
Substrate Surface Roughness ◽  
Medicinal Leeches

Medicinal leeches use their suction discs for locomotion, adhesion to the host and, in the case of the anterior disc, also for blood ingestion. The biomechanics of their suction-based adhesion systems has been little understood until now. We investigated the functional morphology of the anterior and posterior suckers of Hirudo verbana by using light and scanning electron microscopy. Furthermore, we analysed the adhesion qualitatively and quantitatively by conducting behavioural and mechanical experiments. Our high-speed video analyses provide new insights into the attachment and detachment processes and we present a detailed description of the leech locomotion cycle. Pull-off force measurements of the anterior and posterior suction organs on seven different substrates under both aerial and water-submersed conditions reveal a significant influence of the surrounding medium, the substrate surface roughness and the tested organ on attachment forces and tenacities.

scholarly journals Size and structure of the Mediterranean medicinal leech, Hirudo verbana populations inhabiting wetlands around Lake Eğirdir, Turkey

2021 ◽  
Vol 38 (4) ◽  
pp. 437-447
Author(s):  
Mustafa Ceylan ◽  
Osman Çetinkaya
Keyword(s):  
Population Size ◽  
Body Length ◽  
Conservation Status ◽  
Medicinal Leech ◽  
Age Classes ◽  
Control Units ◽  
Hirudo Verbana ◽  
The Mediterranean ◽  
The Stability ◽  
Size And Structure

In the present study size and structure of the Mediterranean medicinal leech (Hirudo verbana Carena, 1820) populations inhabiting wetlands around Lake Eğirdir (Turkey) were investigated. Population size was estimated by removal methods, age classes were estimated for the first time in leeches (Hirudinea) using “Modal Progression Analysis” of body length frequencies using Bhattacharya's method. The population size and biomass of medicinal leeches around Lake Eğirdir were estimated to be 1,562,696 ± 805,613 leeches and 467.26 ± 172.91 kg, respectively. Three age classes were identified; the age group of 0+ was dominant with 78.6%. While 89.9% of the individuals weighed less than 1 g, whereas the broodstock was estimated to represent only 7%. Body weight, body length and condition factor were found to be 0.52 ± 1.19 g, 4.5 ± 2.4 cm and 0.620 ± 0.123, respectively. This study reveals that the population size of H. verbana in the wetlands around Lake Eğirdir is relatively well preserved and there is no significant threat to the sustainability of the exploitation of the medicinal leech populations. It is concluded that the stability of the lake's water budget, the variety and abundance of the host in the undamaged wetlands, the socioeconomic structure of the leech collectors, the sales policies, and the effective activities of conservation and control units might affect conservation status of the medicinal leech populations inhabiting wetlands around Lake Eğirdir.

Seasonal Bioaccumulation of Heavy Metals by Medicinal Leech Hirudo verbana

2018 ◽  
Vol 54 (5) ◽  
pp. 56-62
Author(s):  
L. V. Chornaya ◽  
L. A. Kovalchuk ◽  
N. V. Mikshevich
Keyword(s):  
Heavy Metals ◽  
Medicinal Leech ◽  
Hirudo Verbana

Anticorrosion Protection of Welded Joints of Oil Pipelines

2018 ◽  
Vol 284 ◽  
pp. 1129-1133
Author(s):  
M.A. Ivanov ◽  
P.A. Danilkin ◽  
V.D. Kvashnin
Keyword(s):  
Welded Joints ◽  
High Speed ◽  
Operational Reliability ◽  
Polymer Coatings ◽  
Mechanical Tests ◽  
Technical Standards ◽  
Oil Companies ◽  
Oil Pipelines ◽  
Metal Properties ◽  
Protection Coating

Currently, a problem of destruction of field and interfiled pipelines is topical. One of effective ways to increase an operational reliability of pipes is to protect them with different coatings. To protect the inner surface of oil pipelines the polymer coatings are used which cover the full length except the end sections – zones of mounted welded joints. Oil companies are interested in development of a technology of metal coating applying to the end sections, which provides both reliability of protection system of inner surfaces of pipes, and workability and high speed of mounting of pipelines. This paper shows the analysis of protection methods of pipeline end sections. The tests of metallized coatings are held. We identified the significant shortcomings of metallized coatings. There is a held experiment on applying of corrosion resistant coating by surfacing. There are the calculated heating zones while the surfacing operation. We defined the minimum necessary length of section for applying the protection coating. A chemical analysis showed that the expected structure in a surfaced coating is an austenite with inclusions of ferrite and martensite. Metallographic research showed that the protection layer is fully melted with a base metal of a pipe and represents a homogeneous structure without pores and slag inclusions. Mechanical tests confirmed the compliance of pipe metal properties to the requirements of normative and technical standards.

scholarly journals Froghoppers jump from smooth plant surfaces by piercing them with sharp spines

2019 ◽  
Vol 116 (8) ◽  
pp. 3012-3017 ◽  
Author(s):  
Hanns Hagen Goetzke ◽  
Jonathan G. Pattrick ◽  
Walter Federle
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
High Speed ◽  
Blue Staining ◽  
Acceleration Phase ◽  
Synthetic Adhesives ◽  
3D Environments ◽  
Attachment Mechanism ◽  
Plant Surfaces ◽  
Scanning Electron

Attachment mechanisms used by climbing animals facilitate their interactions with complex 3D environments and have inspired novel types of synthetic adhesives. Here we investigate one of the most dynamic forms of attachment, used by jumping insects living on plants. Froghopper insects can perform explosive jumps with some of the highest accelerations known among animals. As many plant surfaces are smooth, we studied whether Philaenus spumarius froghoppers are able to take off from such substrates. When attempting to jump from smooth glass, the insects’ hind legs slipped, resulting in weak, uncontrolled jumps with a rapid forward spin. By contrast, on smooth ivy leaves and smooth epoxy surfaces, Philaenus froghoppers performed strong jumps without any slipping. We discovered that the insects produced traction during the acceleration phase by piercing these substrates with sharp spines of their tibia and tarsus. High-speed microscopy recordings of hind legs during the acceleration phase of jumps revealed that the spine tips indented and plastically deformed the substrate. On ivy leaves, the spines of jumping froghoppers perforated the cuticle and epidermal cell walls, and wounds could be visualized after the jumps by methylene blue staining and scanning electron microscopy. Improving attachment performance by indenting or piercing plant surfaces with sharp spines may represent a widespread but previously unrecognized strategy utilized by plant-living insects. This attachment mechanism may also provide inspiration for the design of robotic grippers.

scholarly journals CFD Analysis of Jet Mixing in Low NOx Flametube Combustors

1991 ◽  
Author(s):  
M. V. Talpallikar ◽  
C. E. Smith ◽  
M. C. Lai ◽  
J. D. Holdeman
Keyword(s):  
Aspect Ratio ◽  
High Speed ◽  
Flux Ratio ◽  
Nox Emissions ◽  
Nasa Lewis Research ◽  
Lean Burn ◽  
Jet Mixing ◽  
Critical Technology ◽  
The Rich ◽  
Cfd Analyses

The Rich-burn/Quick-mix/Lean-burn (RQL) combustor has been identified as a potential gas turbine combustor concept to reduce NOx emissions in High Speed Civil Transport (HSCT) aircraft. To demonstrate reduced NOx levels, cylindrical flametube versions of RQL combustors are being tested at NASA Lewis Research Center. A critical technology needed for the RQL combustor is a method of quickly mixing by-pass combustion air with rich-burn gases. In this study, jet mixing in a cylindrical quick-mix section was numerically analyzed. The quick-mix configuration was five inches in diameter and employed twelve radial-inflow slots. The numerical analyses were performed with an advanced, validated 3-D Computational Fluid Dynamics (CFD) code named REFLEQS. Parametric variation of jet-to-mainstream momentum flux ratio (J) and slot aspect ratio was investigated. Both non-reacting and reacting analyses were performed. Results showed mixing and NOx emissions to be highly sensitive to J and slot aspect ratio. Lowest NOx emissions occurred when the dilution jet penetrated to approximately mid-radius. The viability of using 3-D CFD analyses for optimizing jet mixing was demonstrated.

scholarly journals Lag, lock, sync, slip: the many ‘phases’ of coupled flagella

2014 ◽  
Vol 11 (94) ◽  
pp. 20131160 ◽  
Author(s):  
Kirsty Y. Wan ◽  
Kyriacos C. Leptos ◽  
Raymond E. Goldstein
Keyword(s):  
High Speed ◽  
Model Organism ◽  
Dynamic Coordination ◽  
Phase Slippage ◽  
Transient Loss ◽  
Flagellar Regeneration ◽  
Resolution Imaging ◽  
The Rich ◽  
Cilia And Flagella ◽  
The Many

In a multitude of life's processes, cilia and flagella are found indispensable. Recently, the biflagellated chlorophyte alga Chlamydomonas has become a model organism for the study of ciliary motility and synchronization. Here, we use high-speed, high-resolution imaging of single pipette-held cells to quantify the rich dynamics exhibited by their flagella. Underlying this variability in behaviour are biological dissimilarities between the two flagella—termed cis and trans , with respect to a unique eyespot. With emphasis on the wild-type, we derive limit cycles and phase parametrizations for self-sustained flagellar oscillations from digitally tracked flagellar waveforms. Characterizing interflagellar phase synchrony via a simple model of coupled oscillators with noise, we find that during the canonical swimming breaststroke the cis flagellum is consistently phase-lagged relative to, while remaining robustly phase-locked with, the trans flagellum. Transient loss of synchrony, or phase slippage , may be triggered stochastically, in which the trans flagellum transitions to a second mode of beating with attenuated beat envelope and increased frequency. Further, exploiting this alga's ability for flagellar regeneration, we mechanically induced removal of one or the other flagellum of the same cell to reveal a striking disparity between the beatings of the cis and trans flagella, in isolation. These results are evaluated in the context of the dynamic coordination of Chlamydomonas flagella.

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