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• Flash-annealing of Cu 47.5 Zr 47.5 Al 5 and Cu 46.5 Zr 48 Al 4 Nb 1.5 metallic-glass ribbons. • Cu 10 Zr 7 precipitates enhance mechanical performance of obtained composites materials. • Nanocrystalline materials have good corrosion resistance in NaCL and H 2 SO 4 solutions. Metallic-glass–crystal composites of Cu 47.5 Zr 47.5 Al 5 and Cu 10 Zr 7 -reinforced Cu 46.5 Zr 48 Al 4 Nb 1.5 nanocrystalline materials are obtained by flash-annealing of metallic-glass ribbons. In situ high-energy X-ray diffraction reveals the deformation mechanism of the alloys upon tensile loading. For the composites and nanocrystalline materials, a small remaining amount of the metallic glass and/or the presence of the Cu 10 Zr 7 phase significantly increase the value of yield stress while maintaining good tensile ductility. In general, the obtained materials exhibit a reversible martensitic transformation (MT) between the B2 CuZr and B19′/B33 phases during tensile loading and unloading. However, the reversibility of MT depends on the alloy composition, crystalline phases, and the number of (un)loading cycles. Serrated-like fluctuations on tensile stress-strain curves and a sign of twinning in the Cu 10 Zr 7 crystals are found after yielding in the Cu 10 Zr 7 -reinforced Cu 46.5 Zr 48 Al 4 Nb 1.5 nanocrystalline materials. Electrochemical measurements show that Cu 46.5 Zr 48 Al 4 Nb 1.5 nanocrystalline material has good corrosion resistance in NaCl and H 2 SO 4 solutions, even better than the parent metallic glasses in some aspects. [Display omitted] [ABSTRACT FROM AUTHOR]

The current study has investigated the thunderstorm induced atmospheric gravity waves (AGWs) over Indian region based on the perturbation signatures in ionospheric total electron content (TEC) measurement. Robust traveling ionospheric disturbance (TID) signature has been identified along the east side of the thunderstorm affected area. Neutral wind was found to have a favorable impact in this aspect for a certain time duration of the day by modulating the vertical wavelength. The role of temperature was analyzed in terms of kinematic viscosity which is a crucial component, especially over tropical region, for wave dissipation and reflection along its propagation path. Ray tracing algorithm is also applied with varying kinematic viscosity and thermal diffusivity for retrieval of possible ray paths and source location of observed waves. A statistical investigation has been carried out to identify the dissipation altitude of observed waves along the ray paths. It has been found that all waves dissipated at almost a constant altitude for a specific kinematic viscosity and above this altitude vertical wavelength was found to decrease. The ray paths interacted at a common point which was located at about 125 km altitude and was very close to the region of maximum lightning activity. It can also be noted that the observed phase velocities can't be achieved by a wave below the turbopause. It indicates that the observed waves were excited from a secondary source and not directly connected to convective system. The study provides an in‐depth analysis of mesoscale system induced gravity wave propagation and dissipation over tropical region. Mesoscale convective systems in tropical regions are key sources of low‐frequency atmospheric gravity waves (GWs). GWs usually generates above thunderstorm altitudes and propagates to ionospheric heights through dissipation and atmospheric filtering. This is one of the first study about the propagation mechanism of thunderstorm‐generated GWs at thermospheric altitude over the Indian region. The concentric source of the wave was evidenced by concentric rings in traveling ionospheric disturbance and phase velocity Vp$\left({V}_{p}\right)$trends which coincides with high lightning location. It is also observed that wave with Vp${V}_{p}$above 250 m/s were unable to propagate below 100 Km and indicate the secondary source of the gravity wave at thermospheric altitudes which was not directly related with the thunderstorm activity. The effect of background temperature on the propagation mechanism was tested by examining the role of kinematic viscosity on wave dissipation. The maximum momentum fluxes were found around 260 km altitude for a specific kinematic viscosity profile. Interestingly, the ray‐tracing validation fails one scale height above this altitude, aligning with theories of wave dissipation or reflection. Additionally, it was also observed that all waves interacted at a common point in both horizontal and temporal domains. This is one of the key finding of this investigation. The study presents signature of thunderstorm induced gravity wave above lower thermospheric altitudePhase velocity and intrinsic period increased linearly from thunderstorm locationAn almost unique wave dissipation altitude found for all waves for a specific kinematic viscosity The study presents signature of thunderstorm induced gravity wave above lower thermospheric altitude Phase velocity and intrinsic period increased linearly from thunderstorm location An almost unique wave dissipation altitude found for all waves for a specific kinematic viscosity

The Python Indian Weather Radar Toolkit, abbreviated as "pyiwr", is an open-source Python library tailored for the purpose of handling data from the Indian Doppler Weather Radar (DWR). This paper provides a comprehensive overview of the pyiwr, which serves as a toolkit to read, analyze, process, and visualize weather radar data. Apart from this, the toolkit offers a range of robust functions implementing various algorithms covering several aspects of the radar data processing and quality control that facilitate the manipulation and analysis of weather radar data. To demonstrate the practical applicability of pyiwr, various case studies are presented, focusing on processing raw reflectivity data (clutter correction), Quantitative Precipitation Estimation (QPE) using Z-R relationship and time-series analysis of reflectivity and rain intensity, both spatially as well as at a specific location, during various meteorological events. This module enhances the accessibility and compatibility of radar data, enabling researchers, weather forecasters, and hydrologists to efficiently work with DWR data (particularly Indian DWR) that fosters advancements in weather radar research and applications. The open availability of pyiwr's source code on GitHub ensures that researchers and practitioners can not only access the toolkit but also contribute to its ongoing development. • An advanced open-source library designed to effortlessly work with Indian DWR data. • Compatible with raw and NetCDF radar data file formats and also with existing radar toolkits. • Provides convenient functions for automated data processing, analysis and visualization. • Algorithms are included for radar QPE, reflectivity correction and timeseries analysis, etc. [ABSTRACT FROM AUTHOR]

Morphing materials are typically either very compliant to achieve large shape changes or very stiff but with small shape changes that require large actuation forces. Interestingly, fish fins overcome these limitations: fish fins do not contain muscles, yet they can change the shape of their fins with high precision and speed while producing large hydrodynamic forces without collapsing. Here, we present a ‘stiff’ morphing beam inspired from the individual rays in natural fish fins. These synthetic rays are made of acrylic (PMMA) outer beams (‘hemitrichs’) connected with rubber ligaments which are 3–4 orders of magnitude more compliant. Combinations of experiments and models of these synthetic rays show strong nonlinear geometrical effects: the ligaments are ‘mechanically invisible’ at small deformations, but they delay buckling and improve the stability of the ray at large deformations. We use the models and experiments to explore designs with variable ligament densities, and we generate design guidelines for optimum morphing shape (captured using the first moment of curvature), that capture the trade-offs between morphing compliance (ease of morphing the structure) and flexural stiffness. The design guidelines proposed here can help the development of stiff morphing bioinspired structures for a variety of applications in aerospace, biomedicine or robotics.

Sodium 3‐amino‐2‐hydroxyanthraquinone‐1‐sulphonate (AQS) is an analogue of the anthracycline based chemotherapeutic drugs that was prepared as a part of the reported study. As the surfactant micelles mimics the biological membrane the present study comprises the interaction of AQS with an anionic surfactant, sodium dodecyl sulfate (SDS) in aqueous media at pH 7.4 which was monitored by using UV–Visible spectroscopy. The aim of the study is to see whether the present molecule penetrates a biological membrane. Different binding parameters like binding constant, partition coefficient, and corresponding Gibbs free energies of the interaction of AQS and its distribution between aqueous media and SDS micelles were measured. The study revealed that hydrophobic interactions play the most important role in binding of AQS to SDS micelles. To see whether AQS really permeates a biological membrane and induces apoptosis, it was allowed to interact with A549 human lung cancer cells. This study established the fact that AQS results apoptosis by means of nucleation into this cell. A model study on the interaction of sodium 3‐amino‐2‐hydroxyanthraquinone‐1‐sulphonate (AQS) with the anionic surfactant micelles such as sodium dodecyl sulfate was carried out in aqueous media at pH 7.4 by using UV‐Visible spectroscopy. This was used to explain the permeation of AQS in A549 human lung cancer cells leading to apoptosis.

The leaves of AnnonareticulataLinn (牛心果niú x ınguǒ; Bullock’s heart), a member of Annonaceae family, have been used extensively in folk medicine; however, its wound healing potential is yet to be explored. Our aim was to investigate the wound healing ability of A. reticulataleaf extract in vitroand in streptozotocin induced diabetic mice model.

To effectively interpret the fluid flow dynamics in the molten metal pool, a numerical model was established. The moving repetitive Gaussian laser pulse is irradiated in the work piece. The consideration of laser scanning speed makes the transport phenomena complex. The continuity and momentum equations are solved to get the flow velocity of the molten metal in the melt pool. The energy equation is solved to know the temperature field in the work piece. The algebraic equations obtained after discretization of the governing equations by Finite Volume Method (FVM) are then solved by the Tri Diagonal Matrix Method. Enthalpy-porosity technique is used to capture the position of the melt front which determines the shape of the melt pool. Marangoni convection is considered to know its effect on the shape of the melt pool. The surface tension coefficient is taken as both positive and negative value while calculating the Marangoni force. The two possible cases will cause the Marangoni force to distort the flow dynamics in the melt pool . It's dominance over the buoyancy force in controlling the melt pool shape is focused in the present study. Further, the present model will present an insight to the consequences of laser scanning velocity over the melt pool dimensions and shape.

We have synthesized model hydrophobic silicone thin films on gold surfaces by a two-step covalent grafting procedure. An amino-functionalized gold surface reacts with monoepoxy-terminated polydimethylsiloxane (PDMS) viaa click reaction, resulting in a covalently attached nanoscale thin film of PDMS, and the click chemistry synthesis route provides great selectivity, reproducibility, and stability in the resulting model hydrophobic silicone thin films. The asymmetric interaction forces between the PDMS thin films and mica surfaces were measured with the surface forces apparatus in aqueous sodium chloride solutions. At an acidic pH of 3, attractive interactions are measured, resulting in instabilities during both approach (jump-in) and separation (jump-out from adhesive contact). Quantitative analysis of the results indicates that the Derjaguin–Landau–Verwey–Overbeek theory alone, i.e., the combination of electrostatic repulsion and van der Waals attraction, cannot fully describe the measured forces and that the additional measured adhesion is likely due to hydrophobic interactions. The surface interactions are highly pH-dependent, and a basic pH of 10 results in fully repulsive interactions at all distances, due to repulsive electrostatic and steric-hydration interactions, indicating that the PDMS is negatively charged at high pH. We describe an interaction potential with a parameter, known as the Hydra parameter, that can account for the extra attraction (low pH) due to hydrophobicity as well as the extra repulsion (high pH) due to hydrophilic (steric-hydration) interactions. The interaction potential is general and provides a quantitative measure of interfacial hydrophobicity/hydrophilicity for any set of interacting surfaces in aqueous solution.

Site diversity is one of the few fade mitigation techniques that are actively explored to overcome the serious fading condition encountered in high‐frequency satellite communication, particularly over tropical regions. However, the study of site diversity performance is limited over tropical regions due to unavailability of simultaneous fade measurements from multiple locations as well as the lack of data on spatial rain pattern from radar measurements. We propose here a copula‐based Bayesian approach to study the site diversity performance utilizing only a single location's drop size distribution measurement. Study of diversity performance has been done for Ahmedabad, India, utilizing 3 years of disdrometer data. Effects of frequency, elevation angle, and site separation on diversity gain are investigated using the proposed method. Results are compared with two ITU‐R models, site diversity results from Italy, a temperate region, and Singapore, another tropical location. The spatial correlation obtained through this technique is also compared with radar observations in Oklahoma, a totally different climatic regime. The simple ITU‐R model is found to be underpredicting the diversity gain significantly for the present location whereas the explicit ITU‐R model shows overprediction above 8 dB for single‐site rain attenuation values. Comparison with measurements at Italy shows similar diversity gains for low single‐site attenuation values. The results reported for Singapore matches well with the present method. The study indicates room for improvement in the present ITU‐R model considering the different nature of tropical rain and that the proposed method is suitable for such a purpose. Site diversity prediction is based on single disdrometer measurementsCopula‐based Bayesian approach is used for spatial field generationComparison with ITU‐R model shows significant differences

Abstract: Climatic changes and the recent surge in weather extremities are alarming concerns for society today. Tropical squall events with extremely heavy rainfall and lightning are among the very severe ones among such activities. Usually, squalls have a leading convective edge followed by a stratiform trail; however, the reverse is also observed in rare cases. This work presented a thorough study on a conventional and an unconventional squall with nearly similar severities from a tropical location, Kolkata. The study reports notably high wind gusts and lightning activities during both events, with the latter one showing higher values. The CAPE increase and OLR drops were significant in both the cases. Breakage of storm front were noticed in the first squall, which possibly resulted in higher CAPE surrounding the study location even though the localised value was slightly larger during the second event. The unconventional squall having a shorter life cycle showed weaker vertical wind shear. The cloud system during the second squall structure showed dominance of smaller cloud particles and lower cloud top pressure than the first event, whereas the cloud mask fraction and cloud water path were large in this case. The rain microphysics has been studied for the two said events and a greater number of drops has been observed in the reflectivity through region than in the stratiform phase for the squall with trailing convective line, unlike the one with conventional structure. The rain microphysical properties showed clearly distinguishable behaviour during the three phases of the squall passage for both the events. Exceptionally high avalues in empirical relation between Zand Rwere noticed in both the cases.The study reports higher path attenuation during the first event. The study can be useful in improving the understanding of the efficiency of different atmospheric and precipitation microphysical features in the predictability of a mesoscale system. Research highlights:

The current work has presented a thorough analysis of two tropical squalls with different organisational modes.

The variation in associated weather variables has been studied for the two events.

A thorough study of precipitation microphysics has been carried out for the two squalls.

The conventional factors used for prediction of mesoscale systems were analysed in detail for these cases to understand the efficiency of these elements in prediction of an unconventional convective system like a squall with a leading stratiform edge studied here.

Rough/patterned/textured surfaces with nano/microcavities that broaden below the surfaceknown as “re-entrants”can be omniphobic (macroscopic contact angle greater than 90° for both water and oils). The existing theoretical models that explain the effects of texture on wetting are complex and do not provide a simpleprocedure for predicting the thermodynamically stable and metastable states and their corresponding contact angles (for example, wetting states that involve partially filled cavities). Here, we develop a simple-to-apply wetting model that allows for (1) predicting a priorithe wetting state (partially or fully filled) of the cavities both under and outside the liquid droplet and the corresponding macroscopic contact angles on any type of textured surface; (2) determining the conditions under which metastable states exist; and (3) engineering specific nano/microtextures that yield any desired macroscopic contact angle, θt, for a given intrinsic contact angle θ0. Subsequently, we experimentallydemonstrate how one can use the model to predict the metastable and the thermodynamically stable contact angles on nondeformable textured surfaces consisting of arrays of axisymmetric cavities/protrusions. In this model, we do not consider the effects of gravitational forces, Laplace pressure of the droplet, line tension, droplet impact velocity, and quantitative aspects of contact angle hysteresis. Nonetheless, the model is suitable for accurately predicting the contact angles of macroscopic droplets (droplet volume ∼1 μL and base diameters <2 mm), which is of immense relevance in engineering. In the experimental section we also discuss the suitability of the model to be extended in order to include the effects of contact angle hysteresis on the macroscopic apparent contact angle on textured surfaces. Controlling these macroscopic contact angles, whether higher or lower than the intrinsic angle, θ0, is desirable for many applications including nonwetting, self-cleaning, and antifouling surfaces and for completely wetting/spreading applications, such as creams, cosmetics, and lubricant fluids.

Wetting of rough surfaces involves time-dependent effects, such as surface deformations, nonuniform filling of surface pores within or outside the contact area, and surface chemistries, but the detailed impact of these phenomena on wetting is not entirely clear. Understanding these effects is crucial for designing coatings for a wide range of applications, such as membrane-based oil–water separation and desalination, waterproof linings/windows for automobiles, aircrafts, and naval vessels, and antibiofouling. Herein, we report on time-dependent contact angles of water droplets on a rough polydimethylsiloxane (PDMS) surface that cannot be completely described by the conventional Cassie–Baxter or Wenzel models or the recently proposed Cassie-impregnated model. Shells of sand dollars (Dendraster excentricus) were used as lithography-free, robust templates to produce rough PDMS surfaces with hierarchical, periodic features ranging from 1 × 10–7to 1 × 10–4m. Under saturated vapor conditions, we found that in the short term (<1 min), the contact angle of a sessile water droplet on the templated PDMS, θSDT= 140 ± 3°, was accurately described by the Cassie–Baxter model (predicted θSDT= 137°); however, after 90 min, θSDTfell to 110°. Fluorescent confocal microscopy confirmed that the initial reduction in θSDTto 110° (the Wenzel limit) was primarily a Cassie–Baxter to Wenzel transition during which pores within the contact area filled gradually, and more rapidly for ethanol–water mixtures. After 90 min, the contact line of the water droplet became pinned, perhaps caused by viscoelastic deformation of the PDMS around the contact line, and a significant volume of water began to flow from the droplet to pores outside the contact region, causing θSDTto decrease to 65° over 48 h on the rough surface. The system we present here to explore the concept of contact angle time dependence (dynamics) and modeling of natural surfaces provides insights into the design and development of long- and short-lived coatings.

The role of friction in the functional performance of biomaterial interfaces is widely reckoned to be critical and complicated but poorly understood. To better understand friction forces, we investigated the natural adaptation of the holdfast or byssus of mussels that live in high-energy surf habitats. As the outermost covering of the byssus, the cuticle deserves particular attention for its adaptations to frictional wear under shear. In this study, we coacervated one of three variants of a key cuticular component, mussel foot protein 1, mfp-1 [(1) Mytilus californianusmcfp-1, (2) rmfp-1, and (3) rmfp-1-Dopa], with hyaluronic acid (HA) and investigated the wear protection capabilities of these coacervates to surfaces (mica) during shear. Native mcfp-1/HA coacervates had an intermediate coefficient of friction (μ ∼0.3) but conferred excellent wear protection to mica with no damage from applied loads, F⊥, as high as 300 mN (pressure, P, > 2 MPa). Recombinant rmfp-1/HA coacervates exhibited a comparable coefficient of friction (μ ∼0.3); however, wear protection was significantly inferior (damage at F⊥> 60 mN) compared with that of native protein coacervates. Wear protection of rmfp-1/HA coacervates increased 5-fold upon addition of the surface adhesive group 3,4-dihydroxyphenylalanine, (Dopa). We propose a Dopa-dependent wear protection mechanism to explain the differences in wear protection between coacervates. Our results reveal a significant untapped potential for coacervates in applications that require adhesion, lubrication, and wear protection. These applications include artificial joints, contact lenses, dental sealants, and hair and skin conditioners.

Early confirmation of endotracheal tube placement is of paramount importance to prevent hypoxia and its catastrophic consequences. Despite certain limitations, capnography is considered the gold standard to evaluate the proper placement of an endotracheal tube. Ultrasound is a novel tool with some definitive advantages over capnography. It enables a real-time view and can be performed quickly; furthermore, it is independent of pulmonary blood flow and does not require lung ventilation. In this review, we aimed to evaluate the diagnostic accuracy of transtracheal ultrasound in detecting endotracheal intubation. We completed an extensive search of MEDLINE®, EMBASE™, The Cochrane Library, KoreaMed, LILACS, OpenGrey, and the World Health Organization International Clinical Trials Registry from their inception to September 4, 2014. The studies that met the inclusion criteria were pooled and a meta-analysis was conducted. Eleven studies and 969 intubations were included in the final analysis. Eight studies and 713 intubations were performed in emergency situations and the others were carried out in elective situations. Transtracheal ultrasonography’s pooled sensitivity and specificity with 95% confidence intervals (CIs) were 0.98 (95% CI 0.97 to 0.99) and 0.98 (95% CI 0.95 to 0.99), respectively. In emergency scenarios, transtracheal ultrasonography showed an aggregate sensitivity and specificity of 0.98 (95% CI 0.97 to 0.99) and 0.94 (95% CI 0.86 to 0.98), respectively. Transtracheal ultrasound is a useful tool to confirm endotracheal intubation with an acceptable degree of sensitivity and specificity. It can be used in emergency situations as a preliminary test before final confirmation by capnography. La confirmation rapide du positionnement du tube endotrachéal est d’une importance capitale pour prévenir l’hypoxie et ses conséquences catastrophiques. En dépit de certaines limites, on considère que la capnographie constitue la référence universelle permettant d’évaluer un bon positionnement du tube endotrachéal. L’échographie est un nouvel outil qui offre des avantages certains par rapport à la capnographie. Elle permet une vue en temps réel et peut être réalisée rapidement; en outre, elle est indépendante du débit sanguin pulmonaire et ne nécessite pas de ventilation pulmonaire. Au cours de cette étude, nous avons cherché à évaluer la précision diagnostique de l’échographie transtrachéale pour la détection de l’intubation endotrachéale. Nous avons mené une recherche extensive dans les bases de données MEDLINE®, EMBASE™, The Cochrane Library, KoreaMed, LILACS, OpenGrey, ainsi que dans le Registre des essais cliniques internationaux de l’Organisation mondiale de la santé depuis leur création jusqu’au 4 septembre 2014. Les études répondent aux critères d’inclusion ont été regroupées pour permettre la réalisation d’une méta-analyse. Onze études et 969 intubations ont été incluses dans l’analyse finale. Huit études et 713 intubations ont été pratiquées dans des situations d’urgence et les autres ont été réalisées dans des situations programmées. Après regroupement, la sensibilité et la spécificité de l’échographie transtrachéale, avec intervalles de confiance (IC) à 95 %, ont été respectivement de 0,98 (IC à 95 %: 0,97 à 0,99) et 0,98 (IC à 95 %: 0,95 à 0,99). Dans les situations d’urgence, la sensibilité et la spécificité groupées de l’échographie transtrachéale ont été, respectivement, de 0,98 (IC à 95 %: 0,97 à 0,99) et 0,94 (IC à 95 %: 0,86 à 0,98). L’échographie transtrachéale est un outil utile pour confirmer l’intubation endotrachéale avec des niveaux de sensibilité et de spécificité acceptables. Elle peut être utilisée dans les situations d’urgence comme test préliminaire avant une confirmation définitive par la capnographie.

Patients undergoing craniotomy, experience moderate to severe pain in postoperative period. Flupirtine does not have side effects like sedation and increase postoperative bleeding, so it may be a useful analgesic in neurosurgical patients. We designed this prospective, randomized, double blind, placebo-controlled study to evaluate the role of flupirtine for postcraniotomy pain and compare it with diclofenac sodium.

Most geckos can rapidly attach and detach from almost any kind of surface. This ability is attributed to the hierarchical structure of their feet (involving toe pads, setal arrays, and spatulae), and how they are moved (articulated) to generate strong adhesion andfriction forces on gripping that rapidly relax on releasing. Inspired by the gecko's bioadhesive system, various structured surfaces have been fabricated suitable for robotic applications. In this study, x–y–zasymmetric, micrometer‐sized rectangular flaps composed of polydimethylsiloxane (PDMS) were fabricated using massively parallel micro‐electromechanical systems (MEMS) techniques with the intention of creating directionally responsive, high‐to‐low frictional‐adhesion toe pads exhibiting properties similar to those found in geckos. Using a surface forces apparatus (SFA), the friction and adhesion forces of both vertical (symmetric) and angled/tilted (x–y–zasymmetric) microflaps under various loading, unloading and shearing conditIons were investigated. It was found that the anisotropic structure of tilted microflaps gives very different adhesion and tribological forces when articulated along different x–y–zdirections: high friction and adhesion forces when articulated in the y–zplane along the tilt (+y) direction, which is also the direction of motion, and weak friction and adhesion forces when articulated against the tilt (–y) direction. These results demonstrate that asymmetric angled structures, as occur in geckos, are required to enable the gecko to optimize the requirements of high friction and adhesion on gripping, and low frictional‐adhesion on releasing. These properties are intimately coupled to a (also optimum) articulation mechanism. We discuss how both of these features can be simultaneously optimized in the design of robotic systems that can mimic the gecko adhesive system.

Abstract: A complex of Fe(III) with 1,2 dihydroxy 9, 10, anthraquinone (DHA) has been prepared. The metal ion forms a 1ratio3 complex with DHA. The complex is formed due to the dissociation of one proton per ligand bound to the metal ion. The stability constant of the Fe(III) complex is 1.61·1032. The complex reduces the catalytic flow of electrons from NADH to molecular O2 through NADH dehydrogenase over DHA. The Fe(III) compelx is seen to be an efficient radiosensitizer towards gamma-radiation induced degradation of thymine in a nitrous oxide saturated medium.

The discovery and understanding of gecko ‘frictional-adhesion’ adhering and climbing mechanism has allowed researchers to mimic and create gecko-inspired adhesives. A few experimental and theoretical approaches have been taken to understand the effect of surface roughness on synthetic adhesive performance, and the implications of stick–slip friction during shearing. This work extends previous studies by using a modified surface forces apparatus to quantitatively measure and model frictional forces between arrays of polydimethylsiloxane gecko footpad-mimetic tilted microflaps against smooth and rough glass surfaces. Constant attachments and detachments occur between the surfaces during shearing, as described by an avalanchemodel. These detachments ultimately result in failure of the adhesion interface and have been characterized in this study. Stick–slip friction disappears with increasing velocity when the flaps are sheared against a smooth silica surface; however, stick–slip was always present at all velocities and loads tested when shearing the flaps against rough glass surfaces. These results demonstrate the significance of pre-load, shearing velocity, shearing distances, commensurability and shearing direction of gecko-mimetic adhesives and provide us a simple model for analysing and/or designing such systems.