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Reuse of electronic wastes is a critical aspect for a more sustainable circular economy as it provides the simplest and most direct route to extend the lifespan of non-renewable resources. Herein, the distinctive surface and micro topographical features of computer electronic-plastic (E-plastic) scraps were unconventionally repurposed as a substrate material to guide the growth and differentiation of human adipose-derived mesenchymal stem cells (ADSCs). Specifically, the E-plastics were scavenged from discarded computer components such as light diffuser plate (polyacrylates), prismatic sheet (polyethylene terephthalate), and keyboards (acrylonitrile butadiene styrene) were cleaned, sterilized, and systematically characterized to determine the identity of the plastics, chemical constituents, surface features, and leaching characteristics. Multiparametric analysis revealed that all the E-plastics could preserve stem-cell phenotype and maintain cell growth over 2 weeks, rivalling the performance of commercial tissue-culture treated plates as cell culture plastics. Interestingly, compared to commercial tissue-culture treated plastics and in a competitive adipogenic and osteogenic differentiation environment, ADSCs cultured on the keyboard and light diffuser plastics favoured bone cells formation while the grating-like microstructures of the prismatic sheet promoted fat cells differentiation via the process of contact guidance. Our findings point to the real possibility of utilizing discarded computer plastics as a "waste-to-resource" material to programme stem cell fate without further processing nor biochemical modification, thus providing an innovative second-life option for E-plastics from personal computers. National Environmental Agency (NEA) National Research Foundation (NRF) This research is supported by the National Research Foundation, Singapore, and National Environment Agency, Singapore under its Closing the Waste Loop Funding Initiative (Award No. USS-IF-2018-4).

International audience; The interplay between light photons and nanomaterials can give rise to many striking phenomena. Surface plasmon resonance (SPR), which is one such plasmonic sensing mechanism, is gaining much attention from the biomedical fraternity. Two-dimensional (2D) nanomaterials like transition-metal dichalcogenides (TMDCs) and graphenes are recently discovered nanomaterials that have favorable properties like high optical absorption. These materials have been applied extensively in the fields of drug delivery and cancer therapy. However, their applications in the area of plasmonic biosensing need to be explored more. Hence, using commercial SPR sensors, we demonstrate the effectiveness of heterostructured monolayer nanosheets of graphene and WS2 for a plasmonic-based detection system of a specific ligand-analyte interaction between bovine serum albumin (BSA) and anti-BSA. Our detection technique does not require any complex functionalization scheme as the graphene-WS2 nanosheet-coated gold chip can attach protein molecules through hydrophobic interactions. The limit of detection (LOD) obtained for the anti-BSA protein is 0.44 μg/mL.

International audience; Electro-optic modulators are among the most important building blocks in optical communication networks. Lithium niobate, for example, has traditionally been widely used to fabricate high-speed optical modulators due to its large Pockels effect. Another material, barium titanate, nominally has a 50 times stronger r-parameter and would ordinarily be a more attractive material choice for such modulators or other applications. In practice, barium titanate thin films for optical waveguide devices are usually grown on magnesium oxide due to its low refractive index, allowing vertical mode confinement. However, the crystal quality is normally degraded. Here, a group of scandate-based substrates with small lattice mismatch and low refractive index compared to that of barium titanate is identified, thus concurrently satisfying high crystal quality and vertical optical mode confinement. This work provides a platform for nonlinear on-chip optoelectronics and can be promising for waveguide-based optical devices such as Mach-Zehnder modulators, wavelength division multiplexing, and quantum optics-on-chip.

As for other multivalent systems, the interface between the calcium (Ca) metal anode and the electrolyte is of paramount importance for reversible plating/stripping. Here, we combined experimental and theoretical approaches to unveil the potential solid electrolyte interphase (SEI) components enabling facile Ca plating. Borates compounds, in the form of cross-linked polymers are suggested as divalent conducting component. A pre-passivation protocol with such SEI is demonstrated and allows to broaden the possibility for electrolyte formulation. We also demonstrated a 10-fold increase in Ca plating kinetics by tuning the cation solvation structure in the electrolyte limiting the degree of contact ion pair., Funding from the European Union's Horizon 2020 research and innovation program H2020 is acknowledged: European Research Council (ERC-2016-STG, CAMBAT grant agreement no. 715087) and H2020-MSCA-COFUND-2016 (DOC-FAM, grant agreement no. 754397). A. Ponrouch is grateful to the Spanish Ministry for Economy, Industry and Competitiveness Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496) and to Prof. D. Lemordant (Tours University, France) for stimulating discussions. P. Canepa acknowledges funding from the National Research Foundation under his NRFF NRFF12-2020-0012 and the ANR-NRF NRF2019-NRF-ANR073 Na-MASTER. P. Canepa acknowledges the National Supercomputing Centre, Singapore (https://www.nscc.sg). This work has been done in the frame of the Doctoral Degree Program in Materials Science by the Universitat Autònoma de Barcelona. The FTIR experiments were performed at MIRAS beamline at ALBA Synchrotron with the collaboration of ALBA staff.

International audience; Plasmon-based sensing relies on the interaction of photons with nanostructured materials. Surface plasmon resonance (SPR) biological and chemical sensors offer unique advantages of real-time and label-free detection techniques and therefore, they have been around in the commercial market for many decades. The principle of the Goos–Hanchen (GH) shift, whereby linearly polarized light undergoes a small lateral shift upon total internal reflection at a dielectric surface, is highly sensitive to refractive index (RI) changes in the sensing medium and can thus be utilized for plasmonic sensing. 2D materials such as graphene can boost the plasmonic efficiency of these sensors because of their excellent optical properties. Herein, a customized GH shift–based SPR sensor is devised using graphene-coated Au chips. With the help of experimental results, it is shown that graphene can enhance the sensitivity of the conventional Au-only configuration 2.35 times.

The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions., The National Research Foundation, Prime Minister’s Office, Singapore under its Medium sized centre programme, and for the NRF fellowship to C.A.N., award No. NRF-RF 2010-03, is kindly acknowledged for supporting this research. C.F., N.C., M.M.-T., C.R. and J.V. acknowledge the CSIC funded i-LINK0841project, the EU FP7 program through ACMOL collaborative project (GA n 618082), ERC StG 2012-306826 e-GAMES, CIG (PCIG10-GA-2011-303989) and ITN iSwitch (GA no. 642196), the financial support from the DGI (Spain) (CTQ2013-40480-R), Spanish Ministry of Economy and Competitiveness, through the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (SEV-2015-0496), the Generalitat de Catalunya (2014SGR-17) and the Networking Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN); N.C. acknowledges the RyC program; C.F. is enroled in the Materials Science PhD program of UAB.

International audience; Plasmonic sensing relies on the interaction between the electromagnetic light wave and free electrons that reside at the interface of two materials, one of them being a metal. Surface plasmon resonance (SPR)‐based biosensing has distinct advantages of providing real‐time and label‐free detection technique that is capable of giving accurate and repeatable results. 2D nanomaterials (graphene and transition metal dichalcogenides [TMDCs] such as MoS2 and WS2) have recently gained high popularity in the field of biomedical sciences. Using Biacore commercial SPR machine manufactured by GE Healthcare, the efficacy of various combinations of these materials coated on the plasmonic metal gold (Au) (Au + MoS2, Au + WS2, Au + graphene, Au + graphene + MoS2, and Au + graphene + WS2) is evaluated, in enhancing the sensitivity of the biosensor as compared with the standard Kretschmann configuration (only Au). Some simulation results are also presented at incident light wavelengths of 633 and 785 nm that are based on the angular interrogation method. To conclude, it is found that the sensitivity in the increasing order is: only Au

In this communication, we show preliminary results on transmissive TiO2 wire-grid polarizers (WGP) operating in the deep ultraviolet (DUV) range. WGP are devices based on strips of materials with large values of the modulus of the dielectric constant along with high absorption in the operational range. The merit function Π is introduced as a new tool to find the optimum material for WGPs in a given spectral range. The experimental dielectric constant of TiO2 thin films deposited by pulsed laser deposition are obtained through spectroscopic ellipsometry, and the Π function indicates that TiO2 is the best candidate for WGP in the DUV range when it is compared with other oxides. Once the material selection for WGP is done, we present and compare two different design approaches for WGP: one using an effective medium theory for the periodic structure, and the second using finite-difference time-domain (FDTD) analysis. A prototype of WGP is fabricated by electron beam (e-beam) lithography followed by lift-off process; the topography of the sample is analyzed by AFM, and we found noticeable deviations in the grating from the designed values. In preliminary characterization work the effective dielectric constant in two perpendicular orientations is obtained by ellipsometry and the contrast is compared with the design, We acknowledge Singapore Synchrotron Light Source for providing the facility necessary for conducting the research. The Laboratory is a National Research Infrastructure under the National Research Foundation, Singapore.

et al., Bismuth telluride based thermoelectric materials show great promise in electricity generation from waste heat and solid-state refrigeration, but improving their conversion efficiency with economical approaches for widespread use remains a challenge. An economical facile bottom-up approach has been developed to obtain nanostructured powders, which are used to build bulk thermoelectric materials. Using excess tellurium as sacrificial additive to enable liquid-phase sintering in the spark plasma sintering process, the lattice and bipolar contributions to the thermal conductivity are both greatly reduced without compromising too much the power factor, which leads to the achievement of high figure of merit (ZT) in both n-type and p-type bismuth telluride based nanocomposites. The ZT values are 1.59±0.16 for p-type BiSbTe and 0.98±0.07 for n-type BiTeSe at 370 K, which are significantly high for bottom-up approaches. These results demonstrate that solution-chemistry approaches as facile, scalable and low-energy-intensive ways to achieve nanopowders, combined with liquid-phase sintering process, can open up great possibilities in developing high-performance low-price thermoelectric bulk nanocomposites., Q.X. gratefully thanks Singapore National Research Foundation via a Fellowship grant (NRF-RF2009-06) and an Investigator ship grant (NRF-NRFI2015-03), Ministry of Education via a tier2 grant (MOE2012-T2-2-086) and Nanyang Technological University via a start-up grant support (M58110061). F.J.B, M.d.l. M and J.A acknowledge the funding from the Generalitat de Catalunya 2014 SGR 1638 and the Spanish MINECO project e-TNT (MAT2014-59961-C2-2-R). ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295). Q.Y. thanks Singapore A*STAR Pharos program SERC 1527200022. D.P. acknowledges support from Singapore Ministry of Education, Singapore Academic Research Fund Tier-1 (project SUTDT12015005).

We report on spin transport features which are unique to high quality bilayer graphene, in the absence of magnetic contaminants and strong intervalley mixing. The time-dependent spin polarization of a propagating wave packet is computed using an efficient quantum transport method. In the limit of vanishing effects of substrate and disorder, the energy dependence of the spin lifetime is similar to monolayer graphene with an M-shaped profile and minimum value at the charge neutrality point, but with an electron-hole asymmetry fingerprint. In sharp contrast, the incorporation of substrate-induced electron-hole puddles (characteristics of supported graphene either on SiO2 or hBN) surprisingly results in a large enhancement of the low-energy spin lifetime and a lowering of its high-energy values. Such a feature, unique to the bilayer, is explained in terms of a reinforced Dyakonov-Perel mechanism at the Dirac point, whereas spin relaxation at higher energies is driven by pure dephasing effects. This suggests further electrostatic control of the spin transport length scales in graphene devices., This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 696656, Graphene Flagship. S.R. acknowledges Funding from the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund [Project No. FIS2015- 67767-P (MINECO/FEDER)] and the Severo Ochoa Program (MINECO SEV-2013-0295). S.A. acknowledges support from the National Research Foundation of Singapore under its Fellowship programme (NRF-NRFF2012-01) and computational resources from the Centre for Advanced 2D Materials (an NRF midsized center).

Graphitic carbon nitride (g-C3N4), a metal-free semiconductor with a band gap of 2.7 eV, has received considerable attention owing to its fascinating photocatalytic performances under visible-light. g-C3N4 exhibits high thermal and chemical stability and non-toxicity such that it has been considered as the most promising photocatalyst for environmental improvement and energy conservation. Hence, it is of great importance to obtain high-quality g-C3N4 and gain a clear understanding of its optical properties. Herein, we report a high-yield synthesis of g-C3N4 products via heating of high vacuum-sealed melamine powder in an ampoule at temperatures between 450 and 650 °C. Using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), the chemical composition and crystallization of the as-produced g-C3N4 are demonstrated. A systematic optical study of g-C3N4 is carried out with several approaches. The optical phonon behavior of g-C3N4 is revealed by infrared and Raman spectroscopy, and the emission properties of g-C3N4 are investigated using photoluminescence (PL) spectroscopy, while the photocatalytic properties are explored by the photodegradation experiment., Q. X. gratefully thanks Singapore National Research Foundation via a fellowship grant (NRF-RF2009-06), Ministry of Education via a tier2 grant (MOE2012-T2-2-086) and a tier1 grant (2013-T1-002-232). Some of the research leading to these results has received funding from the European Union Seventh Framework Program under Grant Agreement 312483 – ESTEEM2 (Integrated Infrastructure Initiative – I3). AZ acknowledges the German DAAD scholarship program. JA and AG acknowledge the funding from the Spanish MINECO Severo Ochoa Excellence Program at ICN2 and Generalitat de Catalunya 2014SGR1638.