Blood vessels in the mammalian skeletal system control bone formation and support haematopoiesis by generating local niche environments. While a specialized capillary subtype, termed type H, has been recently shown to couple angiogenesis and osteogenesis in adolescent, adult and ageing mice, little is known about the formation of specific endothelial cell populations during early developmental endochondral bone formation. Here, we report that embryonic and early postnatal long bone contains a specialized endothelial cell subtype, termed type E, which strongly supports osteoblast lineage cells and later gives rise to other endothelial cell subpopulations. The differentiation and functional properties of bone endothelial cells require cell-matrix signalling interactions. Loss of endothelial integrin β1 leads to endothelial cell differentiation defects and impaired postnatal bone growth, which is, in part, phenocopied by endothelial cell-specific laminin α5 mutants. Our work outlines fundamental principles of vessel formation and endothelial cell differentiation in the developing skeletal system.

The demand for wearable strain gauges that can detect dynamic human motions is growing in the area of healthcare technology. However, the realization of efficient sensing materials for effective detection of human motions in daily life is technically challenging due to the absence of the optimally designed electrode. Here, we propose a novel concept for overcoming the intrinsic limits of conventional strain sensors based on planar electrodes by developing highly periodic and three-dimensional (3D) bicontinuous nanoporous electrodes. We create a 3D bicontinuous nanoporous electrode by constructing conductive percolation networks along the surface of porous 3D nanostructured poly(dimethylsiloxane) with single-walled carbon nanotubes. The 3D structural platform allows fabrication of a strain sensor with robust properties such as a gauge factor of up to 134 at a tensile strain of 40%, a widened detection range of up to 160%, and a cyclic property of over 1000 cycles. Collectively, this study provides new design opportunities for a highly efficient sensing system that finely captures human motions, including phonations and joint movements.

Realization of sensing multidirectional strains is essential to understanding the nature of complex motions. Traditional uniaxial strain sensors lack the capability to detect motions working in different directions, limiting their applications in unconventional sensing technology areas, like sophisticated human-machine interface and real-time monitoring of dynamic body movements. Herein, a stretchable multidirectional strain sensor is developed using highly aligned, anisotropic carbon nanofiber (ACNF) films via a facile, low-cost, and scalable electrospinning approach. The fabricated strain sensor exhibits semitransparency, good stretchability of over 30%, outstanding durability for over 2500 cycles, and remarkable anisotropic strain sensing performance with maximum gauge factors of 180 and 0.3 for loads applied parallel and perpendicular to fiber alignment, respectively. Cross-plied ACNF strain sensors are fabricated by orthogonally stacking two singlelayer ACNFs, which present a unique capability to distinguish the directions and magnitudes of strains with a remarkable selectivity of 3.84, highest among all stretchable multidirectional strain sensors reported so far. Their unconventional applications are demonstrated by detecting multi-degrees-offreedom synovial joint movements of the human body and monitoring wrist movements for systematic improvement of golf performance. The potential applications of novel multidirectional sensors reported here may shed new light into future development of next-generation soft, flexible electronics.To satisfy the growing interests, significant efforts have been made to improve their overall performances. Various materials and structures, [14][15][16][17][18] including nanosize metals, [19][20][21][22] conductive polymers, [23][24][25] nanocarbon materials, [26][27][28][29][30] and fiber or core-shell structure, [14,16,31] have been utilized to enhance the sensitivity, stretchability, linearity, and stability. Unfortunately, however, these strain sensors are designed to mainly detect a uniaxial strain while sensing multidirectional strains has rarely been accomplished, restricting their widespread applications. [32,33] The difficulty in achieving multidirectional strain sensing is due to the macro-or microscopically isotropic nature of conducting networks of strain sensors, which usually experience similar deformation upon stretching in any direction. To address this issue, geometrically engineered flexible strain gauge rosettes [34] and cross-shaped strain sensors [35] composed of isotropic piezoresistive materials were introduced previously. However, they showed a limited success with a small sensing range and an insufficient capability to distinguish the changes in multiaxial strain conditions because the isotropic piezoresistive materials experience significant destruction in their networks at high strains, regardless of the loading directions. To measure complex motions in 3D space with high accuracy requires rational design and use of suitable materials capable of detect...

Two-dimensional (2D) transitional metal oxides (TMOs) are an attractive class of materials due to the combined advantages of high active surface area, enhanced electrochemical properties, and stability. Among the 2D TMOs, 2D tungsten oxide (WO) nanosheets possess great potential in electrochemical applications, particularly in electrochromic (EC) devices. However, feasible production of 2D WO nanosheets is challenging due to the innate 3D crystallographic structure of WO. Here we report a novel solution-phase synthesis of 2D WO nanosheets through simple oxidation from 2D tungsten disulfide (WS) nanosheets exfoliated from bulk WS powder. The complete conversion from WS into WO was confirmed through crystallographic and elemental analyses, followed by validation of the 2D WO nanosheets applied in the EC device. The EC device showed color modulation of 62.57% at 700 nm wavelength, which is 3.43 times higher than the value of the conventional device using bulk WO powder, while also showing enhancement of ∼46.62% and ∼62.71% in switching response-time (coloration and bleaching). The mechanism of enhancement was rationalized through comparative analysis based on the thickness of the WO components. In the future, 2D WO nanosheets could also be used for other promising applications such as sensors, catalysis, thermoelectric, and energy conversion.