31 years survival rate of ARPE® single-mobility prosthesis in trapeziometacarpal osteoarthritis.

A retrospective study of 41 trapeziometacarpal prostheses showed that the implant survival rate decreased linearly over time with a critical period in the first years; ranging from 83% after 5 years to 50% after 30 years. IV.

Liquid-activated quantum emission from pristine hexagonal boron nitride for nanofluidic sensing.

Liquids confined down to the atomic scale can show radically new properties. However, only indirect and ensemble measurements operate in such extreme confinement, calling for novel optical approaches that enable direct imaging at the molecular level. Here we harness fluorescence originating from single-photon emitters at the surface of hexagonal boron nitride for molecular imaging and sensing in nanometrically confined liquids.

A molecular interpretation of the toughness of multiple network elastomers at high temperature.

SignificanceSoft materials can be toughened by creating dissipative mechanisms in stretchy matrixes. Yet using them over a wide range of temperatures requires dissipative mechanisms independent of stretch rate or temperature. We show that sacrificial covalent bonds in multiple network elastomers are most useful in toughening elastomers at high temperature and act synergistically with viscoelasticity at lower temperature.

Why is mechanical fatigue different from toughness in elastomers? The role of damage by polymer chain scission.

Although elastomers often experience 10 to 100 million cycles before failure, there is now a limited understanding of their resistance to fatigue crack propagation. We tagged soft and tough double-network elastomers with mechanofluorescent probes and quantified damage by sacrificial bond scission after crack propagation under cyclic and monotonic loading. Damage along fracture surfaces and its spatial localization depend on the elastomer design, as well as on the applied load (i.

Anomalous interfacial dynamics of single proton charges in binary aqueous solutions.

Our understanding of the dynamics of charge transfer between solid surfaces and liquid electrolytes has been hampered by the difficulties in obtaining interface, charge, and solvent-specific information at both high spatial and temporal resolution. Here, we measure at the single charge scale the dynamics of protons at the interface between an hBN crystal and binary mixtures of water and organic amphiphilic solvents (alcohols and acetone), evidencing a marked influence of solvation on interfacial dynamics. Applying single-molecule localization microscopy to emissive crystal defects, we observe correlated activation between adjacent ionizable surface defects, mediated by the transport of single excess protons along the solid/liquid interface.

Super-resolved Optical Mapping of Reactive Sulfur-Vacancies in Two-Dimensional Transition Metal Dichalcogenides.

Transition metal dichalcogenides (TMDs) represent a class of semiconducting two-dimensional (2D) materials with exciting properties. In particular, defects in 2D-TMDs and their molecular interactions with the environment can crucially affect their physical and chemical properties. However, mapping the spatial distribution and chemical reactivity of defects in liquid remains a challenge.

Direct observation of water-mediated single-proton transport between hBN surface defects.

Aqueous proton transport at interfaces is ubiquitous and crucial for a number of fields, ranging from cellular transport and signalling, to catalysis and membrane science. However, due to their light mass, small size and high chemical reactivity, uncovering the surface transport of single protons at room temperature and in an aqueous environment has so far remained out-of-reach of conventional atomic-scale surface science techniques, such as scanning tunnelling microscopy. Here, we use single-molecule localization microscopy to resolve optically the transport of individual excess protons at the interface of hexagonal boron nitride crystals and aqueous solutions at room temperature.

Facile Production of Hexagonal Boron Nitride Nanoparticles by Cryogenic Exfoliation.

Fluorescent nanoparticles with optically robust luminescence are imperative to applications in imaging and labeling. Here we demonstrate that hexagonal boron nitride (hBN) nanoparticles can be reliably produced using a scalable cryogenic exfoliation technique with sizes below 10 nm. The particles exhibit bright fluorescence generated by color centers that act as atomic-size quantum emitters.

Making Microfluidic Devices that Simulate Phloem Transport.

Phloem tissues are exquisitely difficult to probe experimentally. The biomimetic approach based on synthetic phloem devices might prove useful by allowing to uncover the dynamics and physicochemical couplings of the phloem. In this chapter we discuss the design of a synthetic microfluidic device simulating phloem transport, and the importance of such a device in testing various hypotheses of phloem physiology.

Atomic rheology of gold nanojunctions.

Despite extensive investigations of dissipation and deformation processes in micro- and nano-sized metallic samples, the mechanisms at play during the deformation of systems with ultimate (molecular) size remain unknown. Although metallic nanojunctions, which are obtained by stretching metallic wires down to the atomic level, are typically used to explore atomic-scale contacts, it has not been possible until now to determine the full equilibrium and non-equilibrium rheological flow properties of matter at such scales. Here, by using an atomic-force microscope equipped with a quartz tuning fork, we combine electrical and rheological measurements on ångström-size gold junctions to study the non-linear rheology of this model atomic system.

Wide-Field Spectral Super-Resolution Mapping of Optically Active Defects in Hexagonal Boron Nitride.

Point defects can have significant impact on the mechanical, electronic, and optical properties of materials. The development of robust, multidimensional, high-throughput, and large-scale characterization techniques of defects is thus crucial for the establishment of integrated nanophotonic technologies and material growth optimization. Here, we demonstrate the potential of wide-field spectral single-molecule localization microscopy (SMLM) for the determination of ensemble spectral properties as well as the characterization of spatial, spectral, and temporal dynamics of single defects in chemical vapor deposition (CVD)-grown and irradiated exfoliated hexagonal boron-nitride materials.

MicroMegascope.

Atomic force microscopy (AFM) allows us to reconstruct the topography of surfaces with resolution in the nanometer range. The exceptional resolution attainable with the AFM makes this instrument a key tool in nanoscience and technology. The core of a standard AFM set-up relies on the detection of the change of the mechanical motion of a micro-oscillator when approaching the sample to image.

Shear thinning in non-Brownian suspensions.

We study the flow of suspensions of non-Brownian particles dispersed into a Newtonian solvent. Combining capillary rheometry and conventional rheometry, we evidence a succession of two shear thinning regimes separated by a shear thickening one. Through X-ray radiography measurements, we show that during each of those regimes, the flow remains homogeneous and does not involve particle migration.

Phloem Loading through Plasmodesmata: A Biophysical Analysis.

In many species, Suc en route out of the leaf migrates from photosynthetically active mesophyll cells into the phloem down its concentration gradient via plasmodesmata, i.e. symplastically.

Pairwise frictional profile between particles determines discontinuous shear thickening transition in non-colloidal suspensions.

The process by which sheared suspensions go through a dramatic change in viscosity is known as discontinuous shear thickening. Although well-characterized on the macroscale, the microscopic mechanisms at play in this transition are still poorly understood. Here, by developing new experimental procedures based on quartz-tuning fork atomic force microscopy, we measure the pairwise frictional profile between approaching pairs of polyvinyl chloride and cornstarch particles in solvent.

Electrostatic interactions between ions near Thomas-Fermi substrates and the surface energy of ionic crystals at imperfect metals.

The electrostatic interaction between two charged particles is strongly modified in the vicinity of a metal. This situation is usually accounted for by the celebrated image charges approach, which was further extended to account for the electronic screening properties of the metal at the level of the Thomas-Fermi description. In this paper we build upon a previous approach [M.

Nanoscale capillary freezing of ionic liquids confined between metallic interfaces and the role of electronic screening.

Room-temperature ionic liquids (RTILs) are new materials with fundamental importance for energy storage and active lubrication. They are unusual liquids, which challenge the classical frameworks of electrolytes, whose behaviour at electrified interfaces remains elusive, with exotic responses relevant to their electrochemical activity. Using tuning-fork-based atomic force microscope nanorheological measurements, we explore here the properties of confined RTILs, unveiling a dramatic change of the RTIL towards a solid-like phase below a threshold thickness, pointing to capillary freezing in confinement.

Passive phloem loading and long-distance transport in a synthetic tree-on-a-chip.

Vascular plants rely on differences in osmotic pressure to export sugars from regions of synthesis (mature leaves) to sugar sinks (roots, fruits). In this process, known as Münch pressure flow, the loading of sugars from photosynthetic cells to the export conduit (the phloem) is crucial, as it sets the pressure head necessary to power long-distance transport. Whereas most herbaceous plants use active mechanisms to increase phloem sugar concentration above that of the photosynthetic cells, in most tree species, for which transport distances are largest, loading seems, counterintuitively, to occur by means of passive symplastic diffusion from the mesophyll to the phloem.

Drop impact and capture on a thin flexible fiber.

When a drop impacts a thin fiber, a critical impact speed can be defined, below which the drop is entirely captured by the fiber, and above which the drop pinches-off and fractures. We discuss here the capture dynamics of both inviscid and viscous drops on flexible fibers free to deform following impact. We characterize the impact-induced elongation of the drop thread for both high and low viscosity drops, and show that the capture dynamics depends on the relative magnitudes of the bending time of the fiber and deformation time of the drop.

[How to avoid operative injury to Martin-Grüber communicating branch in the transmuscular medial approach of the elbow?].

The incidence of Martin-Grüber medio-ulnar communicating branch (MUCB), from median nerve to ulnar nerve, is about 20%. To avoid operative injury to MUCB, the authors suggest some modifications to the medial approach of the elbow. They suggest medial aponeurotomy of the anterior compartment of the forearm, disinsertion of the medial epicondylar muscles with dissection between the flexor carpi ulnaris (FCU) and the other medial epicondylar muscles, not exceeding 3 cm distally.

A joint coordinate system proposal for the study of the trapeziometacarpal joint kinematics.

The International Society of Biomechanics (ISB) has recommended a standardisation for the motion reporting of almost all human joints. This study proposes an adaptation for the trapeziometacarpal joint. The definition of the segment coordinate system of both trapezium and first metacarpal is based on functional anatomy.

[How to define the joint movements unambiguously: proposal of standardization for the trapezometacarpal joint].

In order to define the movements of a joint, clinicians usually use anatomic terms. These terms are clearly understandable for a simple movement, defined in an anatomic plane. However, these terms are ambiguous for complex movements or for movements out of an anatomic plane.

[Flexor digitorum superficialis tendon transfer for intrinsic paralysis in leprosy].

A follow up study was performed in the rehabilitation centre for patients with leprosy in Hôchiminhville - Vietnam. All patients had claw-hand deformity due to ulnar and median nerve intrinsic paralysis. Thirty-two affected hands (128 long fingers) were included in the study.

[The trapezio-metacarpal joint: the strain of the ligaments as a function of the thumb position. Study on an enlarged model].

Introduction: The aim of this paper was to develop an enlarged anatomical model of the trapezio-metacarpal joint in order to measure the strains on the ligaments when this joint was passively moved in several directions under constant loading.

Material And Method: A model of the two first rays of the hand was made in polystyrene, at a X3 enlargement, and the ligaments substituted by rubber bands with well characterized mechanical properties so as to reproduce the actual ratio of stiffness (approximately = 10) of the different tissues (bones and ligaments) found in real life. The first metacarpal was moved in 6 directions as described by Ebskov (1970) and Pieron (1973, 1980) using a small spring exerting a constant force (1.

[Comparison of primary trapezometacarpal cup fixation using mechanical tests].

Introduction: In order to optimise the primary fixation of the cup of the Arpe (Biomet Merck) trapeziometacarpal prosthesis, several geometries have been studied. The mechanical strengths of the primary fixations ensured by cup "with slots", "bladed" and "with crown", have been assessed and compared to the one obtained for the primary anchorage of the Arpe cup.

Method: For each cup, the strength of the primary fixation has been assessed in torsion (torque along the cup axis) and bending (torque perpendicular to the cup axis).