pinecone/core-2020-05-10-deduplication huggingface dataset:
Modulating light with light via giant nano-opto-mechanical nonlinearity
  of plasmonic metamaterial

From the demonstration of saturable absorption by Vavilow and Levshin in
1926, and with invention of the laser, unavailability of strongly nonlinear
materials was a key obstacle for developing optical signal processing, in
particular in transparent telecommunication networks. Today, most advanced
photonic switching materials exploit gain dynamics and near-band and excitonic
effects in semiconductors, nonlinearities in organic media with
weakly-localized electrons and nonlinearities enhanced by hybridization with
metamaterials. Here we report on a new type of artificial nonlinearity that is
nano-opto-mechanical in nature. It was observed in an artificial metamaterial
array of plasmonic meta-molecules supported by a flexible nano-membrane. Here
nonlinearity is underpinned by the reversible reconfiguration of its structure
induced by light. In a film of only 100 nanometres thickness we demonstrated
modulation of light with light using milliwatt power telecom diode lasers.Comment: 6 pages, 5 figure
Tripeptide emulsifiers

Traditional, surfactant based emulsions have applications in the food, cosmetic, encapsulation and materials industries. The majority of the surfactants that are currently in use are based on lipids that are extracted from natural sources, however, other surfactants, based on polypeptides, copolymers and solid particles (Pickering emulsions)are also used. The process by which traditional amphiphilic surfactants stabilize biphasic mixtures by interfacial assembly and the consequent reduction of surface tension is well understood. Although these surfactants are well-suited to stabilize emulsions, they are not always biocompatible or biodegradable. In addition, they may not have sufficient stability at elevated temperatures or extremes of pH, which can limit their utility in a variety of applications. Therefore, it is desirable to identify a class of surfactants that can be tuned, or tailored, to match the application for which they are used
Experimental realization of a topological p-n junction by intrinsic
  defect-grading

A junction between an n- and p-type semiconductor results in the creation of
a depletion region whose properties are at the basis of nowadays electronics.
If realized using topological insulators as constituent materials, p-n
junctions are expected to manifest several unconventional effects with great
potential for applications. Experimentally, all these fascinating properties
remained unexplored so far, mainly because prototypical topological PNJs, which
can be easily realized and investigated, were not readily available. Here, we
report on the creation of topological PNJs which can be as narrow as few tenths
of nm showing a built-in potential of 110meV. These junctions are intrinsically
obtained by a thermodynamic control of the defects distribution across the
crystal. Our results make Bi2Te3 a robust and reliable platform to explore the
physics of topological p-n junction
Design of novel visible light active photocatalyst materials: Surface modified TiO2

Work on the design of new TiO2 based photocatalysts is described. The key concept is the formation of composite structures through the modification of anatase and rutile TiO2 with molecular-sized nanoclusters of metal oxides. Density functional theory (DFT) level simulations are compared with experimental work synthesizing and characterizing surface modified TiO2. DFT calculations are used to show that nanoclusters of metal oxides such as TiO2, SnO/SnO2, PbO/PbO2, ZnO and CuO are stable when adsorbed at rutile and anatase surfaces, and can lead to a significant red shift in the absorption edge which will induce visible light absorption; this is the first requirement for a useful photocatalyst. The origin of the red shift and the fate of excited electrons and holes are determined. For p-block metal oxides the oxidation state of Sn and Pb can be used to modify the magnitude of the red shift and its mechanism. Comparisons of recent experimental studies of surface modified TiO2 that validate our DFT simulations are described. These nanocluster-modified TiO2 structures form the basis of a new class of photocatalysts which will be useful in oxidation reactions and with a correct choice of nanocluster modified can be applied to other reactions
Thermal Scanning at the Cellular Level by an Optically Trapped Upconverting Fluorescent Particle

Single particle spectroscopy in the form of three-dimensional optical manipulation of an upconverting nanoparticle is here used for non-invasive thermal sensing at the cellular level. In particular, a single infrared 980 nm laser beam is used as a three-dimensional optical tweezer and, simultaneously, as an optical excitation source for a single NaYF4:Er3+,Yb3+ upconverting particle. Real time analysis of the thermosensitive green emission of Er3+ ions obtained after Yb3+ excitation provides thermal sensing during optical manipulation. Thus, three-dimensional particle scanning allows for the measurement of thermal gradients in the surroundings of individual cancer cells subjected to a plasmonic-mediated photothermal therapy. It is found that such thermal gradients extends for distances larger than 10 microns, avoiding real single cell photothermal treatments under in vitro conditions. This work introduces to the scientific community a novel and simple approach for high resolution thermal sensing at the cellular level that could constitute a powerful tool for a better understanding of cell dynamics during thermal treatmentsThis work was supported by the Spanish Ministerio de Educación y Ciencia (MAT2013–47395-C4–1-R) and by Banco Santander for “Proyectos de Cooperación Interuniversitaria” (2015/ASIA/06). P.H.G thanks the Spanish Ministerio de Economía y Competitividad (MINECO) for the Juan de la Cierva program. P.R.S thanks the Spanish Ministerio de Economía y Competitividad (MINECO) for the “Promoción del talento y su Empleabilidad en I+D+i” statal progra
Freezing the nonclassical crystal growth of a coordination polymer using controlled dynamic gradients

An experiment was conducted to show that diffusion-limited and kinetically controlled growth regimes occurring in microfluidic devices can provide valuable insights into crystallization processes. The microfluidic channels employed in this study were structured in PDMS master form fabricated by standard photolithographic techniques. Before attaching the cured and structured PDMS mould to a glass coverslip through plasma activation, inlet holes connecting the microfluidic channels were punched with a Biopsy puncher. The cross-sectional dimensions of the microchannels were 50 μm into 50 μm for the four input microchannels, and 250 μm into 50 μm for the main reactor channel. The total length of the main reactor channel was 9 mm. Data were indexed, integrated, and scaled using HKL2000 software. The H atoms were included in theoretical positions but not refined. The low max value was due to the data collection process, which was performed in the BM16 line with only a phi scan. The structure was solved by direct methods using the program SHELXS-97. The AFM results suggest that the early stage isolated seeds organize at a single level and in a perpendicular fashion, leading to the final plate-like crystalline morphologies observed in bulk and at an FFR of 0.1
Enhanced Photocatalytic H2 Production in Core–Shell Engineered Rutile TiO2

The authors thank the Major Basic Research Program, Ministry of Science and Technology of China (2014CB239401), NSFC (Nos. 51422210, 51572266, 51561130157, 51172243, 51521091). GL thanks Newton Advanced FellowshipA rationally designed crystalline Ti3+ core/amorphous Ti4+ shell configuration can reverse the population disparity between holes and electrons reaching the surface of microsized rutile TiO2 photocatalyst, thus significantly enhancing its photocatalytic activity by two orders of magnitude in terms of the hydrogen production rate under the irradiation of UV–vis light.PostprintPeer reviewe
Toward superconducting critical current by design

We present the new paradigm of critical current by design. Analogous to
materials by design, it aims at predicting the optimal defect landscape in a
superconductor for targeted applications by elucidating the vortex dynamics
responsible for the bulk critical current. To highlight this approach, we
demonstrate the synergistic combination of critical current measurements on
commercial high-temperature superconductors containing self-assembled and
irradiation tailored correlated defects by using large-scale time-dependent
Ginzburg-Landau simulations for vortex dynamics.Comment: 12 pages, 6 figures; extended versio
Metal-Organic Covalent Network Chemical Vapor Deposition for Gas Separation

The chemical vapor deposition (CVD) polymerization of metalloporphyrin building units is demonstrated to provide an easily up-scalable one-step method toward the deposition of a new class of dense and defect-free metal–organic covalent network (MOCN) layers. The resulting hyper-thin and flexible MOCN layers exhibit outstanding gas-separation performances for multiple gas pairs.United States. Army Research Office. Institute for Soldier Nanotechnologies (Contract DAAD-19-02D-0002)Luxembourg National Research Fun
Unraveling unprecedented charge carrier mobility through structure property relationship of four isomers of didodecyl[1]benzothieno[3,2-b][1]benzothiophene

Since the dawn of organic electronics in the 1970’s, academic and industrial research efforts have led to dramatic improvements of the solubility, stability, and electronic properties of organic semiconductors (OSCs).[1, 2] The common benchmark to characterize the electrical performances of OSCs is their charge carrier mobility μ (cm2 V–1 s–1), defined as the drift velocity of the charge carrier (cm s–1) per unit of applied electric field (V cm–1). Reaching high mobilities in OSCs is highly desirable as it allows faster operation of transistors and energy savings by reduced calculation times.[2, 3] However, OSCs performances (conventional values usually range from 1 to 10 cm2 V–1 s–1, with highest values obtained with single-crystal devices mostly exempt of structural defects) are still not comparable to that of state-of-the-art inorganic semiconductors (e.g. metal oxides with µ = 20-50 cm2 V–1 s–1 and polycrystalline silicon with µ > 100 cm2 V–1 s–1) thereby hampering important potential technological applications such as flexible organic light-emitting diode (OLED) displays and wearable electronics.[3, 4
Mechanical Isolation of Highly Stable Antimonene under Ambient Conditions

This is the peer reviewed version of the following article: Advanced Materials 28.30 (2016): 6332-6336, which has been published in final form at http://dx.doi.org/10.1002/adma.201602128. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingAntimonene fabricated by mechanical exfoliation is highly stable under atmospheric conditions over periods of months and even when immersed in water. Density functional theory confirms the experiments and predicts an electronic gap of ≈1 eV. These results highlight the use of antimonene for optoelectronics applicationsThis work was supported by MINECO projects Consolider CSD2010-00024, MAT2013- 46753-C2-1 and 2, FIS2013-42002-R and CTQ2013-43698-P, CAM project NANOFRONTMAG-CM (ref. S2013/MIT-2850
Single electron gating of topological insulators

Introducing, observing, and manipulating individual impurities coupled to a
host material offers the opportunity to create new device concepts based on
single spin and charge states. Because of potential applications in spintronics
and magneto-electrics, such an approach would be particularly useful for
topological insulators (TI), a recently discovered material class hosting
spin-momentum- locked surface states. To make them useful for new technologies,
a robust control of their interaction with external perturbations is required.
However, traditional approaches such as metal electrodes or doping proved to be
problematic and resulted in strong mesoscopic fluctuations making the
spin-momentum locking ill-defined. Here, we demonstrate the effective gating of
TIs by coupling molecules to their surface which, by using electric fields,
allow to dynamically control the interface charge state by adding or removing
single electrons. This process creates a robust transconductance bistability
resembling a single-electron transistor. Our findings make hybrid molecule/TI
interfaces functional elements while at the same time pushing miniaturization
at its ultimate limit. This opens a new avenue for all electric-controlled
spintronic devices based on these fascinating materials
Toward a High-Efficient Utilization of Solar Radiation by Quad-Band Solar Spectral Splitting

The promising quad-band solar spectral splitter incorporates the properties of the optical filter and the spectrally selective solar thermal absorber can direct PV band to PV modules and absorb thermal band energy for thermal process with low thermal losses. It provides a new strategy for spectral splitting and offers potential ways for hybrid PVT system design.United States. Department of Energy (contract DE-AR0000471)United States. Advanced Research Projects Agency-Energy (contract DE-AR0000471)United States. Department of Energy. Office of Science. Solid-State Solar Thermal Energy Conversion Center (Award # DE-FG02-09ER46577
Above-Bandgap Photovoltages in Antiferroelectrics

Altres ajuts: COST Action StableNextSol project MP1307The closed circuit photocurrent and open circuit photovoltage of antiferroelectric thin films were characterized both in their ground (antipolar) state and in their polarized state. A sharp transition happens from near zero to large photovoltages as the polarization is switched on, consistent with the activation of the bulk photovoltaic effect. The AFE layers have been grown by a solution processing method (sol?gel synthesis followed by spin coating deposition) onto fluorine-doped tin oxide (FTO), a transparent conducting oxide with low sheet resistance and a higher resilience to high-temperature processing than indium tin oxide and a standard for solar cells such as organometal trihalide perovskites. Light absorption confirmed that the PZO films are, as expected, wide-band gap semiconductors with a gap of 3.7.8 eV and thus highly absorbing in the near-ultraviolet range. On a virgin sample, there is no shortcircuit photocurrent, consistent with the antipolar nature of the ground state. As an external bias voltage is applied, the current remains negligible until suddenly, at the coercive voltage, a spike is observed, corresponding to the transient displacement current caused by the onset of polarization
Topological, Valleytronic, and Optical Properties of Monolayer PbS

We systematically examine the topological, valleytronic, and optical
properties of experimentally accessible PbS (001) few-layers, with a focus on
the monolayer. With even-odd layer-dependent oscillations and without band
inversions, the band gaps cover a wide spectrum from infrared to visible,
making the few-layers promising for optoelectronics. Intriguingly, the uniaxial
(biaxial) compressive strain can tune the trivial monolayer into a
$\mathcal{Z}_2$-topological (topological crystalline) insulator, which may be
utilized for controllable low-power electronic devices. Although elliptical
dichroism vanishes in the monolayer due to inversion symmetry, optical pumping
provides an efficient tool to characterize the three phases and to realize
charge, spin, and valley Hall effects in optoelectronic transport that are
tunable by external strain and light ellipticity.Comment: 6 pages, 5 figures, also see Advanced Science News:
  http://www.advancedsciencenews.com/monolayer-pbs-novel-topological-dual-valley-material
Molding photonic boxes into fluorescent emitters by direct laser writing

We acknowledge financial support from the European Research Council Starting Grant ABLASE (ERC StG 640012), the Scottish Funding Council (via SUPA) and the European Union Marie Curie Career Integration Grant (PCIG12-GA-2012-334407). M.K. acknowledges funding from the EPSRC DTG (EP/M506631/1). S.H. gratefully acknowledges support from the Engineering and Physical Sciences Research Council through the ’Hybrid Polaritonics’ Program Grant (Project EP/M025330/1).Direct laser writing of photonic boxes into active layers of biologically produced recombinant fluorescent protein in optical microcavities is demonstrated. Irradiation with laser light above the photobleaching threshold induces photonic confinement potentials on the order of 40 meV. The technique provides high spatial selectivity and enables room-temperature lasing in protein rings, and circular and elliptical pillars with customized beam shapes.Publisher PDFPeer reviewe
Light control of charge transfer and excitonic transitions in a carbon nanotube/porphyrin hybrid

Carbon nanotube–chromophore hybrids are promising building blocks in order to obtain a controlled electro-optical transduction effect at the single nano-object level. In this work, a strong spectral selectivity of the electronic and the phononic response of a chromophore-coated single nanotube transistor is observed for which standard photogating cannot account. This paper investigates how light irradiation strongly modifies the coupling between molecules and nanotube within the hybrid by means of combined Raman diffusion and electron transport measurements. Moreover, a nonconventional Raman enhancement effect is observed when light irradiation is on the absorption range of the grafted molecule. Finally, this paper shows how the dynamics of single electron tunneling in the device at low temperature is strongly modified by molecular photoexcitation. Both effects will be discussed in terms of photoinduced excitons coupled to electronic levels
Strategies for Improving the Functionality of Zeolitic Imidazolate Frameworks: Tailoring Nanoarchitectures for Functional Applications

Zeolitic imidazolate frameworks (ZIFs), a subclass of metal–organic frameworks (MOFs) built with tetrahedral metal ions and imidazolates, offer permanent porosity and high thermal and chemical stabilities. While ZIFs possess some attractive physical and chemical properties, it remains important to enhance their functionality for practical application. Here, an overview of the extensive strategies which have been developed to improve the functionality of ZIFs is provided, including linker modifications, functional hybridization of ZIFs via the encapsulation of guest species (such as metal and metal oxide nanoparticles and biomolecules) into ZIFs, and hybridization with polymeric matrices to form mixed matrix membranes for industrial gas and liquid separations. Furthermore, the developed strategies for achieving size and shape control of ZIF nanocrystals are considered, which are important for optimizing the textural characteristics as well as the functional performance of ZIFs and their derived materials/hybrids. Moreover, the recent trends of using ZIFs as templates for the derivation of nanoporous hybrid materials, including carbon/metal, carbon/oxide, carbon/sulfide, and carbon/phosphide hybrids, are discussed. Finally, some perspectives on the potential future research directions and applications for ZIFs and ZIF-derived materials are offered.Full Tex
Intrinsically polar elastic metamaterials

The ability to design and fabricate materials with tailored mechanical
properties, combined with immunity to damage, is a frontier of materials
engineering. For example, materials which are characterized by elastic
properties that depend on the position inside a medium are required in
applications where structural stability has to be combined with a soft and
compliant surface, like in impact protection and cushioning. A gradient in the
elastic properties can be built from a single material, varying gradually the
bulk porosity of the material or its geometrical structure. However, if such a
gradient is built into the material at production, damage or wearing over time
might expose unwanted elastic properties. Here, we implement a design principle
for a spatially inhomogeneous material based on topological band-theory for
mechanical systems. The resulting inhomogeneity is stable against wearing and
even cutting the material in half. We show how, by creating a periodic elastic
material with topological properties, one can create an intrinsically polar
behavior, where a face with a given surface normal is stiff while its opposing
face is soft
Tuning of the optical, electronic, and magnetic properties of boron nitride nanosheets with oxygen doping and functionalization

Engineering of the optical, electronic, and magnetic properties of hexagonal boron nitride (<i>h</i>-BN) nanomaterials via oxygen doping and functionalization has been envisaged in theory. However, it is still unclear as to what extent these properties can be altered using such methodology because of the lack of significant experimental progress and systematic theoretical investigations. Therefore, here, comprehensive theoretical predictions verified by solid experimental confirmations are provided, which unambiguously answer this long-standing question. Narrowing of the optical bandgap in <i>h</i>-BN nanosheets (from ≈5.5 eV down to 2.1 eV) and the appearance of paramagnetism and photoluminescence (of both Stokes and anti-Stokes types) in them after oxygen doping and functionalization are discussed. These results are highly valuable for further advances in semiconducting nanoscale electronics, optoelectronics, and spintronics
Selective high frequency mechanical actuation driven by the VO2
  electronic instability

Micro- and nano-electromechanical resonators are a fundamental building block
of modern technology, used in environmental monitoring, robotics, medical tools
as well as fundamental science. These devices rely on dedicated electronics to
generate their driving signal, resulting in an increased complexity and size.
Here, we present a new paradigm to achieve high-frequency mechanical actuation
based on the metal-insulator transition of VO$\mathrm{_2}$, where the steep
variation of its electronic properties enables to realize high-frequency
electrical oscillations. The dual nature of this phase change, which is both
electronic and structural, turns the electrical oscillations into an intrinsic
actuation mechanism, powered by a small DC voltage and capable to selectively
excite the different mechanical modes of a microstructure. Our results pave the
way towards the realization of micro- and nano-electro-mechanical systems with
autonomous actuation from integrated DC power sources such as solar cells or
micro-batteries.Comment: Main text: 6 pages, 4 figures Supplemental Material: 16 pages, 7
  section
Degradation-Restructuring Induced Anisotropic Epitaxial Growth for Fabrication of Asymmetric Diblock and Triblock Mesoporous Nanocomposites

A novel degradation-restructuring induced anisotropic epitaxial growth strategy is demonstrated for the synthesis of uniform 1D diblock and triblock silica mesoporous asymmetric nanorods with controllable rod length (50 nm to 2 µm) and very high surface area of 1200 m2 g−1. The asymmetric diblock mesoporous silica nanocomposites are composed of a 1D mesoporous organosilicate nanorod with highly ordered hexagonal mesostructure, and a closely connected dense SiO2 nanosphere located only on one side of the nanorods. Furthermore, the triblock mesoporous silica nanocomposites constituted by a cubic mesostructured nanocube, a nanosphere with radial mesopores, and a hexagonal mesostructured nanorod can also be fabricated with the anisotropic growth of mesopores. Owing to the ultrahigh surface area, unique 1D mesochannels, and functionality asymmetry, the obtained match-like asymmetric Au-NR@SiO2&EPMO (EPMO = ethane bridged periodic mesoporous organosilica) mesoporous nanorods can be used as an ideal nanocarrier for the near-infrared photothermal triggered controllable releasing of drug molecules.Griffith Sciences, Queensland Micro and Nanotechnology CentreFull Tex