The modulation of developmental biochemical pathways by mechanical cues is an emerging feature of animal development, but its evolutionary origins have not been explored. Here we show that a common mechanosensitive pathway involving β-catenin specifies early mesodermal identity at gastrulation in zebrafish and Drosophila. Mechanical strains developed by zebrafish epiboly and Drosophila mesoderm invagination trigger the phosphorylation of β-catenin–tyrosine-667. This leads to the release of β-catenin into the cytoplasm and nucleus, where it triggers and maintains, respectively, the expression of zebrafish brachyury orthologue notail and of Drosophila Twist, both crucial transcription factors for early mesoderm identity. The role of the β-catenin mechanosensitive pathway in mesoderm identity has been conserved over the large evolutionary distance separating zebrafish and Drosophila. This suggests mesoderm mechanical induction dating back to at least the last bilaterian common ancestor more than 570 million years ago, the period during which mesoderm is thought to have emerged.

Thermomagnetic patterning (TMP) of 4 μm thick high performance NdFeB hard magnetic films deposited on Si substrates has been achieved using single pulsed laser irradiation. Uniaxially magnetised chessboard and stripe patterns with lateral feature sizes in the range 50–100 μm were produced. The depth of reversal was estimated, using both global (vibrating sample magnetometry) and localized (scanning Hall probe) measurements, to be in the range of 1.1–1.2 μm. A simple model provides semiquantitative agreement with the experimental results. A linear Halbach array was fabricated to demonstrate the potential of TMP for the realization of complex multidirectional microflux sources.

Microwave switching devices based on the semiconductor-metal transition of $\mathrm{V}{\mathrm{O}}_2$ thin films were developped on two types of substrates ($C$ -plane sapphire and $\mathrm{Si}{\mathrm{O}}_2∕\mathrm{Si}$ ), and in both shunt and series configurations. Under thermal activation, the switches achieved up to $30–40\mathrm{dB}$ average isolation of the radio-frequency (rf) signal on $500\mathrm{MHz}–35\mathrm{GHz}$ frequency band with weak insertion losses. These $\mathrm{V}{\mathrm{O}}_2$ -based switches can be electrically activated with commutation times less than $100\mathrm{ns}$ , which make them promising candidates for realizing efficient and simple rf switches.

Animal development consists of a cascade of tissue differentiation and shape change. Associated mechanical signals regulate tissue differentiation. Here we demonstrate that endogenous mechanical cues also trigger biochemical pathways, generating the active morphogenetic movements shaping animal development through a mechanotransductive cascade of Myo-II medio-apical stabilization. To mimic physiological tissue deformation with a cell scale resolution, liposomes containing magnetic nanoparticles are injected into embryonic epithelia and submitted to time-variable forces generated by a linear array of micrometric soft magnets. Periodic magnetically induced deformations quantitatively phenocopy the soft mechanical endogenous snail-dependent apex pulsations, rescue the medio-apical accumulation of Rok, Myo-II and subsequent mesoderm invagination lacking in sna mutants, in a Fog-dependent mechanotransductive process. Mesoderm invagination then activates Myo-II apical accumulation, in a similar Fog-dependent mechanotransductive process, which in turn initiates endoderm invagination. This reveals the existence of a highly dynamic self-inductive cascade of mesoderm and endoderm invaginations, regulated by mechano-induced medio-apical stabilization of Myo-II.

Scanning Hall probe microscopy has been used for the quantitative measurement of the $z$ -component (out-of-plane) of the stray magnetic fields produced by Nd–Fe–B hard magnetic films patterned at the micron scale using both topographic and thermomagnetic methods. Peak-to-peak field values in the range 20–120 mT have been measured at scan heights of $25–30\mu \text{m}$ above the samples. Quantitative comparison between calculated and measured field profiles gives nondestructive access to the micromagnets’ internal magnetic structure. In the case of topographically patterned films the average value of remanent magnetization is extracted; in the case of thermomagnetically patterned films the depth of magnetization reversal is estimated. The measured field profiles are used to derive the spatial variation in the field and field gradient values at distances in the range $0.1–10\mu \text{m}$ above the micromagnet arrays. These length-scales are relevant to the application of the micromagnet arrays for lab-on-chip applications (trapping and confinement of magnetic particles). Very large field and field gradient values as high as 1.1 T and $4.1\times {10}^6\text{T}/\text{m}$ , respectively, are estimated.

The real and imaginary parts of the dielectric function of VO₂ thin films, deposited on r-plane sapphire via pulsed laser deposition, are measured by means of visible-infrared ellipsometry for wavelengths ranging from 0.4 to 15 μm and temperatures within its phase transition. For both the insulator-to-metal (heating) and metal-to-insulator (cooling) transitions, it is shown that the two ellipsometric signals exhibit three temperature-driven behaviors, which are well described by appropriate combinations of the Tauc-Lorentz, Gaussian, and Drude oscillator models. By fitting Bruggeman's effective medium model for the dielectric function to the corresponding measured experimental values, using the volumetric fraction of the VO₂ metallic domains as a fitting parameter for different temperatures within the VO₂ phase transition, we have found that this model is suitable for describing the dielectric function in visible and near-infrared wavelengths (∼0.4 to ∼3.0 μm), but it generally fails for longer infrared ones. Furthermore, the hysteresis loop of the VO₂ emissivity averaged over a relevant interval of wavelengths is determined and shown to vary from ∼0.49, in the insulator phase, to ∼0.16, in the metallic one. These values, based on the VO₂ dielectric function, are consistent with previous measurements reported in the literature, and therefore, our measured data are expected to be useful for describing the behavior of VO₂ films involved in optical and radiative applications.