scholarly journals Insect tricks: two-phasic foot pad secretion prevents slipping

2009 ◽  
Vol 7 (45) ◽  
pp. 587-593 ◽  
Author(s):  
Jan-Henning Dirks ◽  
Christofer J. Clemente ◽  
Walter Federle
Keyword(s):  
Adhesive System ◽  
Continuous Phase ◽  
Stick Insect ◽  
Force Measurements ◽  
Friction Forces ◽  
Adhesive Pads ◽  
Foot Pad ◽  
Detailed Function ◽  
Adhesive Secretion

Many insects cling to vertical and inverted surfaces with pads that adhere by nanometre-thin films of liquid secretion. This fluid is an emulsion, consisting of watery droplets in an oily continuous phase. The detailed function of its two-phasic nature has remained unclear. Here we show that the pad emulsion provides a mechanism that prevents insects from slipping on smooth substrates. We discovered that it is possible to manipulate the adhesive secretion in vivo using smooth polyimide substrates that selectively absorb its watery component. While thick layers of polyimide spin-coated onto glass removed all visible hydrophilic droplets, thin coatings left the emulsion in its typical form. Force measurements of stick insect pads sliding on these substrates demonstrated that the reduction of the watery phase resulted in a significant decrease in friction forces. Artificial control pads made of polydimethylsiloxane showed no difference when tested on the same substrates, confirming that the effect is caused by the insects’ fluid-based adhesive system. Our findings suggest that insect adhesive pads use emulsions with non-Newtonian properties, which may have been optimized by natural selection. Emulsions as adhesive secretions combine the benefits of ‘wet’ adhesion and resistance against shear forces.

Accuracy of Orthodontic Force and Tooth Movement Measurements

1996 ◽  
Vol 23 (3) ◽  
pp. 241-248 ◽  
Author(s):  
Dan Lundgren ◽  
Py Owman-Moll ◽  
Jüri Kurol ◽  
Birgit Mårtensson
Keyword(s):  
Tooth Movement ◽  
Mean Value ◽  
Measurement Methods ◽  
Calibration Data ◽  
Force Measurements ◽  
Accuracy Of Measurement ◽  
Measuring Machine ◽  
Initial Force ◽  
Level Of Agreement

This study was designed to test the accuracy of measurement methods for assessment of force and tooth movement in orthodontic procedures. Daily in vivo measurements of the force produced by activated archwires showed that the initial force declined substantially (by 20 per cent of mean value) within 3 days. Both the ‘trueness’ (validity) and precision of the force measurements, obtained with a strain gauge, were found to be high (SD values were 1·0 cN and 0·4 cN, respectively). Horizontal tooth movements were measured with three different instruments: a slide calliper, a co-ordinate measuring machine, and laser measuring equipment based on holograms. There was a good level of agreement between these methods. This was also confirmed by calibration data. The precision of the methods was (SD values) 0·06, 0·07, and 0·13 mm, respectively. The benefits of the use of the co-ordinate measuring machine are obvious, since it can measure tooth movements in relation to reference planes in all directions.

scholarly journals Hemodynamic forces can be accurately measured in vivo with optical tweezers

2017 ◽  
Author(s):  
Sébastien Harlepp ◽  
Fabrice Thalmann ◽  
Gautier Follain ◽  
Jacky G. Goetz
Keyword(s):  
Optical Tweezers ◽  
Cell Biology ◽  
Accurate Determination ◽  
Force Measurements ◽  
Hemodynamic Forces ◽  
Non Invasive ◽  
Drag Forces ◽  
Measured Flow ◽  
Living Organisms

AbstractForce sensing and generation at the tissular and cellular scale is central to many biological events. There is a growing interest in modern cell biology for methods enabling force measurements in vivo. Optical trapping allows non-invasive probing of pico-Newton forces and thus emerged as a promising mean for assessing biomechanics in vivo. Nevertheless, the main obstacles rely in the accurate determination of the trap stiffness in heterogeneous living organisms, at any position where the trap is used. A proper calibration of the trap stiffness is thus required for performing accurate and reliable force measurements in vivo. Here, we introduce a method that overcomes these difficulties by accurately measuring hemodynamic profiles in order to calibrate the trap stiffness. Doing so, and using numerical methods to assess the accuracy of the experimental data, we measured flow profiles and drag forces imposed to trapped red blood cells of living zebrafish embryos. Using treatments enabling blood flow tuning, we demonstrated that such method is powerful in measuring hemodynamic forces in vivo with accuracy and confidence. Altogether, this study demonstrates the power of optical tweezing in measuring low range hemodynamic forces in vivo and offers an unprecedented tool in both cell and developmental biology.

scholarly journals Rational design of protein-specific folding modifiers

2020 ◽  
Author(s):  
Anirban Das ◽  
Anju Yadav ◽  
Mona Gupta ◽  
R Purushotham ◽  
Vishram L. Terse ◽  
...  
Keyword(s):  
Single Molecule ◽  
Rational Design ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Force Measurements ◽  
Folding Nucleus ◽  
Dynamics Simulations ◽  
General Method

AbstractProtein folding can go wrong in vivo and in vitro, with significant consequences for the living cell and the pharmaceutical industry, respectively. Here we propose a general design principle for constructing small peptide-based protein-specific folding modifiers. We construct a ‘xenonucleus’, which is a pre-folded peptide that resembles the folding nucleus of a protein, and demonstrate its activity on the folding of ubiquitin. Using stopped-flow kinetics, NMR spectroscopy, Förster Resonance Energy transfer, single-molecule force measurements, and molecular dynamics simulations, we show that the ubiquitin xenonucleus can act as an effective decoy for the native folding nucleus. It can make the refolding faster by 33 ± 5% at 3 M GdnHCl. In principle, our approach provides a general method for constructing specific, genetically encodable, folding modifiers for any protein which has a well-defined contiguous folding nucleus.

scholarly journals Hydrodynamically Balanced System: A Review

2021 ◽  
Vol 11 (1-s) ◽  
pp. 147-153
Author(s):  
Pawankumar H Yadav ◽  
Dipak P Kardile ◽  
Madhuri T Deshmukh ◽  
Rajkumar V. Shete
Keyword(s):  
Oral Delivery ◽  
Patient Adherence ◽  
Hollow Microsphere ◽  
Adhesive System ◽  
Evaluation Study ◽  
Gastric Residence Time ◽  
System A ◽  
Main Motive ◽  
Floating System

The most suitable drug delivery route is oral delivery due to its easily administration, patient adherence/ patient capacitance etc. Several approaches have been made for maximizing the G.R.T such as high-density system, floating system, swelling & expanding system and mucoadhesive & bio adhesive system etc. the main motive of reviewing the article is to focus on the mechanism of HBS system, classification with new system such as raft forming system and hollow microsphere, its application, marketed preparation and evaluation study. The procedure of gastric emptying is a complex and may leads to uncertainty for in vivo performance of the DDS. To prevent this type of complex formation and uncertainty, hard work has been done to expand the retention time of DDS for half of the day. The FDDS are beneficial in such process. Keywords: HBS system, GRDDS, gastric residence time (G.R.T), raft forming systems, floating formulations, evaluation study. 

Hormonal Control of the Malpighian Tubules of the Stick Insect, Carausius Morosus

1970 ◽  
Vol 52 (3) ◽  
pp. 653-665 ◽  
Author(s):  
DIANA E. M. PILCHER
Keyword(s):  
Stick Insect ◽  
Hormonal Control ◽  
The State ◽  
Malpighian Tubules ◽  
Suboesophageal Ganglion ◽  
Carausius Morosus ◽  
Corpora Cardiaca ◽  
Diuretic Hormone ◽  
The Brain

1. Urine secretion by isolated Malpighian tubules of Carausius is accelerated by a diuretic hormone which can be extracted from the brain, corpora cardiaca and suboesophageal ganglion. 2. The level of this hormone in the haemolymph varies according to the state of hydration of the insect. 3. The hormone is inactivated by the tubules, and a mechanism is proposed whereby the tubules might be controlled by the hormone in vivo.

scholarly journals Adhesion to Enamel of Teeth Affected by Molar Incisor Hypomineralization: Literature Review

2018 ◽  
Vol 22 (2) ◽  
pp. 57-63
Author(s):  
Apostolina Theocharidou ◽  
Konstantinos Arapostathis
Keyword(s):  
Adhesive System ◽  
In Vitro Studies ◽  
Treatment Modalities ◽  
Tooth Structure ◽  
Resin Infiltration ◽  
Composite Restorations ◽  
Molar Incisor Hypomineralization ◽  
Self Etch

SummaryBackground/Aim: Molar incisor hypomineralization (MIH) is a qualitative defect of systemic origin, affecting permanent first molars and often permanent incisors. The treatment modalities can include, amongst others, fissure sealants for prevention of dental caries and composite restorations. Both require adhesion to tooth structure. The aim of this study was to review the literature on the adhesion to enamel affected by MIH.Material and Methods: A search of PupMed/Medline, ResearchGate and Google Scholar was performed and limited between 2003, when the judgement criteria for MIH were set, and 2016. Thirty-three papers were considered relevant to the subject including five in vivo and six in vitro studies. Studies involving less than ten teeth were excluded.Results: A four-year clinical trial showed that the application of a total-etch 2-step adhesive system prior to sealant placement is superior to the etch-seal technique. Despite the high success rate of composite restorations shown in three clinical longitudinal studies, there are conflicting results over self-etch being superior to total etch adhesive systems. Pretreating the enamel surface, prior to the adhesive system, with fluoride preventive solutions could reduce the mikroleakage under orthodontic brackets. Three in vitro studies provide inconsistent data about NaOCl pretreating potentials to improve adhesion of composite restorations. Resin infiltration, prior to resin restorations, could improve the microhardness of defected enamel, which may lead to increased bond strength, especially in combination with NaOCl pretreatment.Conclusions: Adhesion to enamel affected by molar incisor hypomeralization is inferior compared to normal enamel. Sealants applied with the etch-bond-seal technique have greater retention than with the etch-seal technique. Further research is required to provide evidence of the effectiveness of the adhesive system and pretreatment to achieve optimal bonding to MIH.

scholarly journals In vivoadhesion force measurements ofChlamydomonason model substrates

Soft Matter ◽  
2019 ◽  
Vol 15 (14) ◽  
pp. 3027-3035 ◽  
Author(s):  
Christian Titus Kreis ◽  
Alice Grangier ◽  
Oliver Bäumchen
Keyword(s):  
Adhesion Force ◽  
Force Measurements ◽  
Adhesion Mechanism ◽  
Abiotic Surfaces

A universal adhesion mechanism allowsChlamydomonasto effectively colonize abiotic surfaces, as evidenced byin vivoadhesion force measurements.

scholarly journals Prophylaxis protocols and their impact on bracket friction force

2019 ◽  
Vol 89 (6) ◽  
pp. 883-888
Author(s):  
Sérgio Elias Neves Cury ◽  
Silvio Augusto Bellini-Pereira ◽  
Aron Aliaga-Del Castillo ◽  
Sérgio Schneider ◽  
Arnaldo Pinzan ◽  
...  
Keyword(s):  
Sodium Bicarbonate ◽  
Qualitative Analysis ◽  
Friction Force ◽  
Friction Forces ◽  
Debris Accumulation ◽  
Intergroup Comparison ◽  
Group 3 ◽  
Group 2 ◽  
Sliding Mechanics

ABSTRACT Objective: To evaluate the effect of two different prophylaxis protocols on the friction force in sliding mechanics during in vivo leveling and alignment. Materials and Methods: The sample comprised 48 hemi-arches divided into three groups according to the prophylactic protocol adopted. Group 1 consisted of patients undergoing prophylaxis with sodium bicarbonate, group 2 consisted of patients submitted to prophylaxis with glycine, and group 3 consisted of patients without prophylaxis, as a control. All patients received hygiene instructions and, with the exception of group 3, prophylaxis was performed monthly. After 10 months, the brackets were removed from the oral cavity and submitted to friction force tests and qualitative analysis by scanning electron microscopy. Analysis of variance followed by Tukey tests was performed for intergroup comparison regarding the friction force. Results: The experimental groups presented significantly smaller friction forces than the group without prophylaxis. Accordingly, qualitative analysis showed greater debris accumulation in the group without the prophylactic procedures. Conclusions: Prophylactic blasting with sodium bicarbonate or glycine can significantly prevent an increase of the friction force during sliding mechanics.

Sign in / Sign up

Export Citation Format

Share Document