ORCID Profile
0000-0003-3996-0554
Current Organisations
Nottingham Trent University
,
Universidad Complutense de Madrid Facultad de Medicina
,
Hospital Universitario 12 de Octubre
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Publisher: American Chemical Society (ACS)
Date: 31-10-2016
DOI: 10.1021/ACS.NANOLETT.6B03525
Abstract: The quest for nanoscale light sources with designer radiation patterns and polarization has motivated the development of nanoantennas that interact strongly with the incoming light and are able to transform its frequency, radiation, and polarization patterns. Here, we demonstrate dielectric AlGaAs nanoantennas for efficient second harmonic generation, enabling the control of both directionality and polarization of nonlinear emission. This is enabled by specialized III-V semiconductor nanofabrication of high-quality AlGaAs nanostructures embedded in optically transparent low-index material, thus allowing for simultaneous forward and backward nonlinear emission. We show that the nanodisk AlGaAs antennas can emit second harmonic in preferential direction with a backward-to-forward ratio of up to five and can also generate complex vector polarization beams, including beams with radial polarization.
Publisher: AIP Publishing
Date: 04-2014
DOI: 10.1063/1.4871401
Abstract: We study the quantum correlation of path-entangled states of two photons in coupled one-dimensional waveguide arrays with lattice defects. Both off-diagonal and diagonal defects are considered, which show different effects on the quantum correlation of path-entangled two-photon states. Two-photon bunching or anti-bunching effects can be observed and controlled. The two photons are found to have a tendency to bunch at the side lobes with a repulsive off-diagonal defect, and the path-entanglement of the input two-photon state can be preserved during the propagation. We also found that defect modes may play an important role on the two-photon correlation of path-entangled states in the waveguide arrays. Due to the quantum interference effect, intriguing evolution dynamics of the two-photon correlation matrix elements with oscillation frequencies being either twice of or the same as that of a classical light wave, depending on the position of the correlation matrix element, is observed. Our results show that it is possible to manipulate the two-photon correlation properties of path-entangled states in waveguide arrays with lattice defects.
Publisher: Springer Science and Business Media LLC
Date: 13-04-2018
Publisher: IOP Publishing
Date: 06-2021
Abstract: We propose a universal strategy to realize a broadband control on arbitrary scatterers, through multiple coherent beams. By engineering the phases and litudes of incident beams, one can suppress the dominant scattering partial waves, making the obstacle lose its intrinsic responses in a broadband spectrum. The associated coherent beams generate a finite and static region, inside which the corresponding electric field intensity and Poynting vector vanish. As a solution to go beyond the sum-rule limit, our methodology is also irrespective of inherent system properties, as well as extrinsic operating wavelength, providing a non-invasive control on the wave-obstacles interaction for any kinds of shape.
Publisher: Elsevier BV
Date: 04-2023
Publisher: Elsevier BV
Date: 08-2021
Publisher: Elsevier BV
Date: 10-2021
Publisher: Wiley
Date: 05-03-2020
Publisher: Elsevier BV
Date: 08-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6NR09702B
Abstract: Recent progress in the study of resonant light confinement in high-index dielectric nanostructures suggests a new route for achieving efficient control of both electric and magnetic components of light. It also leads to the enhancement of nonlinear effects near electric and magnetic Mie resonances with an engineered radiation directionality. Here we study the third-harmonic generation from dimers composed of pairs of two identical silicon nanoparticles and demonstrate, both numerically and experimentally, that the multipolar harmonic modes generated by the dimers near the Mie resonances allow the shaping of the directionality of nonlinear radiation.
Publisher: American Chemical Society (ACS)
Date: 26-12-2020
Abstract: High-index III-V semiconductor nanoantennas have gained great attention for enhanced nonlinear light-matter interactions, in the past few years. However, the complexity of nonlinear emission profiles imposes severe constraints on practical applications, such as in optical communications and integrated optoelectronic devices. These complexities include the lack of unidirectional nonlinear emission and the severe challenges in switching between forward and backward emissions, due to the structure of the susceptibility tensor of the III-V nanoantennas. Here, we propose a solution to both issues via engineering the nonlinear tensor of the nanoantennas. The special nonlinear tensorial properties of zinc-blende material can be used to engineer the nonlinear characteristics via growing the nanoantennas along different crystalline orientations. Based on the nonlinear multipolar effect, we have designed and fabricated (110)-grown GaAs nanoantennas, with engineered tensorial properties, embedded in a transparent low-index material. Our technique provides an approach not only for unidirectional second-harmonic generation (SHG) forward or backward emission but also for switching from one to another. Importantly, switching the SHG emission directionality is obtained only by rotating the polarization of the incident light, without the need for physical variation of the antennas or the environment. This characteristic is an advantage, as compared to other nonlinear nanoantennas, including (100)- and (111)-grown III-V counterparts or silicon and germanium nanoantennas. Indeed, (110)-GaAs nanoantennas allow for engineering the nonlinear nanophotonic systems including nonlinear "Huygens metasurfaces" and offer exciting opportunities for various nonlinear nanophotonics technologies, such as nanoscale light routing and light sources, as well as multifunctional flat optical elements.
Publisher: Wiley
Date: 05-03-2019
Abstract: Increasing demand for higher resolution of miniaturized displays requires techniques achieving high contrast tunability of the images. Employing metasurfaces for image contrast manipulation is a new and rapidly growing field of research aiming to address this need. Here, a new technique to achieve image tuning in a reversible fashion is demonstrated by dielectric metasurfaces composed of subwavelength resonators. It is demonstrated that by controlling the temperature of a metasurface the encoded transmission pattern can be tuned. To this end, two sets of nanoresonators composed of nonconcentric silicon disks with a hole that exhibit spectrally sharp Fano resonances and forming a Yin-Yang pattern are designed and fabricated. Through exploitation of the thermo-optical properties of silicon, full control of the contrast of the Yin-Yang image is demonstrated by altering the metasurface temperature by ΔT ≈ 100 °C. This is the first demonstrated technique to control an image contrast by temperature. Importantly, the turning technique does not require manipulating the external stimulus, such as polarization or angle of the illumination and/or the refractive index of this environment. These results open many opportunities for transparent displays, optical switches, and tunable illumination systems.
Publisher: The Optical Society
Date: 05-06-2013
DOI: 10.1364/OE.21.014056
Publisher: Springer Science and Business Media LLC
Date: 04-03-2020
DOI: 10.1186/S13054-020-2791-0
Abstract: The aim of this study is to validate a previously published consensus-based quality indicator set for the management of patients with traumatic brain injury (TBI) at intensive care units (ICUs) in Europe and to study its potential for quality measurement and improvement. Our analysis was based on 2006 adult patients admitted to 54 ICUs between 2014 and 2018, enrolled in the CENTER-TBI study. Indicator scores were calculated as percentage adherence for structure and process indicators and as event rates or median scores for outcome indicators. Feasibility was quantified by the completeness of the variables. Discriminability was determined by the between-centre variation, estimated with a random effect regression model adjusted for case-mix severity and quantified by the median odds ratio (MOR). Statistical uncertainty of outcome indicators was determined by the median number of events per centre, using a cut-off of 10. A total of 26/42 indicators could be calculated from the CENTER-TBI database. Most quality indicators proved feasible to obtain with more than 70% completeness. Sub-optimal adherence was found for most quality indicators, ranging from 26 to 93% and 20 to 99% for structure and process indicators. Significant ( p 0.001) between-centre variation was found in seven process and five outcome indicators with MORs ranging from 1.51 to 4.14. Statistical uncertainty of outcome indicators was generally high five out of seven had less than 10 events per centre. Overall, nine structures, five processes, but none of the outcome indicators showed potential for quality improvement purposes for TBI patients in the ICU. Future research should focus on implementation efforts and continuous reevaluation of quality indicators. The core study was registered with ClinicalTrials.gov, number NCT02210221 , registered on August 06, 2014, with Resource Identification Portal (RRID: SCR_015582).
Publisher: Elsevier BV
Date: 06-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NR01561G
Abstract: An ultra-broadband THz fingerprint metasensor is realized by introducing a pixelated frequency-agile metasurface assembling a one-to-many mapping between spatial and spectral information, paving the way to miniaturizing device footprints.
Publisher: IntechOpen
Date: 09-12-2020
Abstract: Deep learning has become a vital approach to solving a big-data-driven problem. It has found tremendous applications in computer vision and natural language processing. More recently, deep learning has been widely used in optimising the performance of nanophotonic devices, where the conventional computational approach may require much computation time and significant computation source. In this chapter, we briefly review the recent progress of deep learning in nanophotonics. We overview the applications of the deep learning approach to optimising the various nanophotonic devices. It includes multilayer structures, plasmonic/dielectric metasurfaces and plasmonic chiral metamaterials. Also, nanophotonic can directly serve as an ideal platform to mimic optical neural networks based on nonlinear optical media, which in turn help to achieve high-performance photonic chips that may not be realised based on conventional design method.
Publisher: Optica Publishing Group
Date: 16-08-2021
DOI: 10.1364/OE.435046
Abstract: A plasmonic double periodic arranged nanocone array (DPANA) integrated by nanotips and nanogaps exhibit strong capability of light compression, and thus lead to extremely enhanced electric near-field intensity. The DPANA is fabricated by the self-assembled mask integrated with the inductively couple plasma (ICP) etching technology. Finite-difference time-domain (FDTD) simulations suggest that the metallized DPANA can generate a strong hotspot at the sharp tip apex and the nanogap between adjacent sharp tips. The electric-field enhancement characteristic is firstly verified with the help of the second-order surface nonlinear optical response of the metallized DPANA. The surface-enhanced Raman spectroscopy (SERS) examination of the metallized DPANA exhibits high sensitivity due to clearly presenting the Raman spectra of Rhodamine-6G (R6G) with concentrations down to 10 pM and has excellent uniformity, time stability, and recyclability, simultaneously. Furthermore, the principle demonstration of SERS practical application is also performed for thiram. This as-prepared SERS substrate has great potential application for trace amount detection.
Publisher: Springer Science and Business Media LLC
Date: 12-05-2020
DOI: 10.1186/S12910-020-00480-8
Abstract: The European Union (EU) aims to optimize patient protection and efficiency of health-care research by harmonizing procedures across Member States. Nonetheless, further improvements are required to increase multicenter research efficiency. We investigated IRB procedures in a large prospective European multicenter study on traumatic brain injury (TBI), aiming to inform and stimulate initiatives to improve efficiency. We reviewed relevant documents regarding IRB submission and IRB approval from European neurotrauma centers participating in the Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI). Documents included detailed information on IRB procedures and the duration from IRB submission until approval(s). They were translated and analyzed to determine the level of harmonization of IRB procedures within Europe. From 18 countries, 66 centers provided the requested documents. The primary IRB review was conducted centrally ( N = 11, 61%) or locally ( N = 7, 39%) and primary IRB approval was obtained after one ( N = 8, 44%), two ( N = 6, 33%) or three ( N = 4, 23%) review rounds with a median duration of respectively 50 and 98 days until primary IRB approval. Additional IRB approval was required in 55% of countries and could increase duration to 535 days. Total duration from submission until required IRB approval was obtained was 114 days (IQR 75–224) and appeared to be shorter after submission to local IRBs compared to central IRBs (50 vs. 138 days, p = 0.0074). We found variation in IRB procedures between and within European countries. There were differences in submission and approval requirements, number of review rounds and total duration. Research collaborations could benefit from the implementation of more uniform legislation and regulation while acknowledging local cultural habits and moral values between countries.
Publisher: Informa UK Limited
Date: 17-10-2020
DOI: 10.1080/09638288.2020.1832589
Abstract: There is conflicting literature on the effect of post- utation pain on quality of life (QOL) and no available literature on the relationship of pain medications to QOL of utees in pain. The aims of the study were to compare QOL in lower limb utees with significant pain to those with minimal pain and compare QOL in utees on multiple pain medications (≥3 and/or ≥ 40 mg morphine equivalent/day) to those on minimal. Cross-sectional study of utees ( Post- utation pain was common (69%), but only 13% of the participants were using more pain medications. High-pain interference and poor self-efficacy were associated with poorer QOL after adjusting for age, gender and cause of utation. High medication use was associated with high-pain interference and poor self-efficacy, but there was minimal correlation between pain scores and medication usage ( Post- utation pain continues to be a major determinant of QOL in lower limb utees, but the role of pain medications on an utee's QOL remains unclear.IMPLICATIONS FOR REHABILITATIONAn utee's QOL is affected by the severity of their post- utation pain even beyond six months post their utation.An utee with more pain may not necessarily take more pain medications to manage their pain. The amount of pain medications taken may not influence their self-reported QOL.Pain and QOL assessment should be integrated into routine clinical evaluation of adult utees. Standardized screening tools and/or formative assessment can be utilized for assessing QOL.
Publisher: SPIE-Intl Soc Optical Eng
Date: 29-04-2020
Publisher: American Association for the Advancement of Science (AAAS)
Date: 14-09-2018
Abstract: Metasurfaces should allow wafer-thin surfaces to replace bulk optical components. Two reports now demonstrate that metasurfaces can be extended into the quantum optical regime. Wang et al. determined the quantum state of multiple photons by simply passing them through a dielectric metasurface, scattering them into single-photon detectors. Stav et al. used a dielectric metasurface to generate entanglement between spin and orbital angular momentum of single photons. The results should aid the development of integrated quantum optic circuits operating on a nanophotonic platform. Science , this issue p. 1104 , p. 1101
Publisher: American Association for the Advancement of Science (AAAS)
Date: 29-07-2022
Abstract: Metasurfaces consisting of nanoscale structures are underpinning new physical principles for the creation and shaping of quantum states of light. Multiphoton states that are entangled in spatial or angular domains are an essential resource for many quantum applications however, their production traditionally relies on bulky nonlinear crystals. We predict and demonstrate experimentally the generation of spatially entangled photon pairs through spontaneous parametric down-conversion from a metasurface incorporating a nonlinear thin film of lithium niobate covered by a silica meta-grating. We measure the correlations of photon pairs and identify their spatial antibunching through violation of the classical Cauchy-Schwarz inequality, witnessing the presence of multimode entanglement. Simultaneously, the photon-pair rate is strongly enhanced by 450 times as compared to unpatterned films because of high-quality-factor resonances. These results pave the way to miniaturization of various quantum devices by incorporating ultrathin metasurfaces functioning as room temperature sources of quantum-entangled photons.
Publisher: Research Square Platform LLC
Date: 30-06-2022
DOI: 10.21203/RS.3.RS-1755479/V1
Abstract: High quality (Q) factor optical resonators are indispensable for many photonic devices. While very large Q-factors can be obtained theoretically in guided mode settings, free-space implementations suffer from various limitations on the narrowest possible linewidth in real experiments. In these devices, the largest Q-factors are hindered by radiation loss induced by fabrication disorder. Complex photonic designs have been explored to enhance this response through either delicate engineering the topological features or carefully breaking symmetries. Here, we put forward a simple strategy to enable ultrahigh-Q guided-mode resonances in all-dielectric metasurfaces without breaking symmetry or carefully engineering topological quantities. We introduce a patterned perturbation layer on top of a multilayer waveguide system, aimed at exciting tailored guided-mode resonances from free space. We demonstrate that the associated Q-factors are inversely proportional to the perturbation squared, suggesting a simple way of achieving extremely high-Q resonances as the perturbation is reduced. The resonant wavelength can be conveniently tuned through material or structural parameters, such as the thickness and refractive index or the metasurface period, within a robust design strategy amenable for implementation in various platforms. We experimentally demonstrate such high-Q resonances at telecom wavelengths by fabricating a low-index photoresist layer photonic crystal slab on top of a 220nm top layer SOI substrate. The measurements show Q-factors up to 2.39x10 5 , comparable to the largest Q-factor obtained by topological engineering, while the resonant wavelength is tuned by varying the lattice constant of the top perturbation layer. Our results hold great promise for exciting applications, such as sensors and filters.
Publisher: Optica Publishing Group
Date: 03-11-2021
DOI: 10.1364/OL.443079
Abstract: Plasmonic tip nanofocusing has gained much attention owing to its wide application in the field of nanospectroscopy. Here, we present the Au nanosphere (AuNS)-assisted coupling ultrafast surface plasmon polaritons (SPP) background-free tip nanofocusing. The plasmonic tip was prepared by attaching an AuNS on the shaft of an Au conical tip fabricated by electrochemical etching. The AuNS was adopted as an antenna to couple the far-field excitation light to the propagating SPP along the shaft to the tip apex for achieving power compression. Importantly, we experimentally and theoretically demonstrate that such a plasmonic tip can realize background-free ultrafast SPP tip nanofocusing with radially polarized features in a wide spectral range based on the localized SPP resonance effect supported by AuNS. Furthermore, the intensity of the tip nanofocusing light field has strong polarization dependence under linearly polarized light excitation, providing a powerful platform for spatiotemporal light control on the nanoscale. Our technique realizes remote excitation of background-free tip nanofocusing with a structured light feature, and it holds promising potential for tip-enhanced nanospectroscopies, nonlinear nanophotonics, etc.
Publisher: Wiley
Date: 03-07-2017
Publisher: Optica Publishing Group
Date: 07-12-2022
DOI: 10.1364/OE.475580
Abstract: Resonance coupling in the regime of bound states in the continuum (BICs) provides an efficient method for engineering nanostructure’s optical response with various lineshape while maintaining an ultra-narrow linewidth feature, where the quality factor of resonances plays a crucial role. Independent manipulation of the Q factors of BIC resonances enables full control of interaction behavior as well as both near- and far-field light engineering. In this paper, we harness reflection symmetry (RS) and translational symmetry (TS) protected BIC resonances supported in an asymmetric dimer lattice and investigate Q -factor-mediated resonance coupling behavior under controlled TS and RS perturbations. We focus on in-plane electrical dipole BIC (ED i -BIC) and magnetic dipole BIC (MD-BIC) which are protected by RS, and out-of-plane electrical dipole BIC (ED o -BIC) protected by TS. The coupling between ED i -BIC and ED o -BIC exhibits a resonance crossing behavior where the transmission spectrum at the crossing could be tuned flexibly, showing an electromagnetically induced transparency lineshape or satisfying the lattice Kerker condition with pure phase modulation capability depending on TS and RS perturbed Q factors. While the coupling between MD-BIC and ED o -BIC shows an avoided resonance crossing behavior, where the strongly coupled resonances would lead to the formation of a Friedrich–Wintgen BICs whose spectral position could also be shifted by tuning the Q factors. Our results suggest an intriguing platform to explore BIC resonance interactions with independent Q factor manipulation capability for realizing multi-functional meta-devices.
Publisher: American Physical Society (APS)
Date: 10-2021
Publisher: Elsevier BV
Date: 11-2021
Publisher: Opto-Electronic Advances
Date: 2022
Publisher: Springer Science and Business Media LLC
Date: 19-12-2018
Publisher: Wiley
Date: 14-11-2021
Abstract: Pure phase modulation of light is vital for a number of optical devices such as spatial light modulators and beam steering in light detection and ranging (LIDAR) technologies. Tunable metasurfaces have recently provided a feasible alternative to existing technologies, allowing for ultra‐high miniaturisation while enabling high transmission efficiency and tunability under small external stimuli. However, despite the recent advances in the field, no pure phase tuning has been demonstrated in transmissive devices, for ex le, any implementation of continuous phase tuning is accompanied by sizable litude modulation or low efficiency. Here, it is shown that the optical anisotropy of the surrounding material can enable phase‐only tuning of optical metasurfaces in the full 2π range with unitary efficiency over a sizable bandwidth. A practical implementation of this concept based on a liquid‐crystal infiltrated metasurface operating in the regime of extreme Huygens condition is further proposed. In this way, the full 2π phase‐only tunability in transmission can be enabled by controlling bias voltage and temperature variation of the surrounding liquid crystal.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D1NR08088A
Abstract: Single vertical nanowire photodetectors from ordered InP nanowire arrays were fabricated by using the focused ion beam technique to directly investigate the light–matter interaction in nanowire arrays and its effect on photodetector performance.
Publisher: Elsevier BV
Date: 11-2019
Publisher: American Chemical Society (ACS)
Date: 16-09-2022
DOI: 10.1021/ACS.NANOLETT.2C02739
Abstract: Low-cost large-area chirality meta-devices (CMDs) with adjustable optical chirality are of great interest for polarization-sensitive imaging, stereoscopic display, enantioselectivity analysis, and catalysis. Currently, CMDs with adjusted chiroptical responses in the mid-infrared to terahertz band have been demonstrated by exploiting photocarriers of silicon, pressure, and phase-change of GSTs but are still absent in the visible band, which in turn limits the development of chiral nanophotonic devices. Herein, by employing a phase-change material (Sb
Publisher: The Optical Society
Date: 25-09-2009
DOI: 10.1364/OE.17.018292
Publisher: MDPI AG
Date: 17-09-2018
Abstract: We design an asymmetric nonlinear optical nanoantenna composed of a dielectric nanodisc and an adjacent nanobar. The proposed composite structure made of AlGaAs exhibits resonant response at both the fundamental and doubled frequencies. Being driven by the strong magnetic dipole resonance at the pump wavelength and a high-quality mode at the harmonic wavelength, the efficient second-harmonic radiation is generated predominantly along the vertical directions under the normally incident plane-wave excitation.
Publisher: Springer Science and Business Media LLC
Date: 05-08-2021
Publisher: Springer Science and Business Media LLC
Date: 29-10-2015
DOI: 10.1038/SREP15805
Abstract: Bending light in a controllable way is desired in various applications such as beam steering, navigating and cloaking. Different from the conventional way to bend light by refractive index gradient, transformation optics or special beams through wavefront design such as Airy beams and surface plasmons, we proposed a mechanism to bend light via resonant adiabatic optical transition between Floquet-Bloch (FB) modes from different FB bands in longitudinally modulated photonic lattices. The band structure of longitudinally modulated photonic lattices was calculated by employing the concept of quasi-energy based on the Floquet-Bloch theory, showing the existence of band discontinuities at specific resonant points which cannot be revealed by the coupled-mode theory. Interestingly, different FB bands can be seamlessly connected at these resonant points in longitudinally modulated photonic lattices driven by adiabatically varying the longitudinal modulation period along the propagation direction, which stimulates the adiabatic FB mode transition between different FB bands.
Publisher: Wiley
Date: 27-12-2022
Abstract: It is well established that for symmetry‐protected bound states in the continuum (BICs), introducing the broken geometry symmetry in a dielectric metasurface transforms such a BIC into a quasi‐BIC (QBIC) with high‐quality factor (Q‐factor). Typically, the smaller the asymmetry parameter, the larger the Q‐factor. However, it is very challenging to fabricate such nanostructures with an ultra‐small asymmetry parameter, thus limiting the measured Q‐factor of QBIC. In this work, the authors demonstrated that BICs can be sustained at Γ‐point in an asymmetric dielectric metasurface, whose unit cell is composed of a dielectric cuboid with an off‐centre hole inside it. Multipole decompositions and near‐field distributions indicate that the toroidal dipole dominates the nature of such a QBIC. Furthermore, the authors found that such a BIC is robust against the shape of the hole. Besides, two BICs at different wavelengths can be achieved by applying either a rectangular hole or a rectangular lattice. Finally, the authors presented experimental verifications of BIC types by fabricating asymmetric silicon metasurfaces. Measurement results show that the Q‐factor of QBIC can reach almost 5,000. The results may enrich the library of BICs and find exciting applications in developing high‐performance photonics devices, such as nanolasers, biosensors and enhanced nonlinear harmonic generation.
Publisher: Walter de Gruyter GmbH
Date: 17-08-2020
Abstract: We put forward the multipolar model which captures the physics behind linear and nonlinear response driven by high-quality (high- Q ) supercavity modes in subwavelength particles. We show that the formation of such trapped states associated with bound states in the continuum (quasi-BIC) can be understood through multipolar transformations of coupled leaky modes. The quasi-BIC state appears with increasing the order of the dominating multipole, where dipolar losses are completely suppressed. The efficient optical coupling to this state in the AlGaAs nanodisk is implemented via azimuthally polarized beam illumination matching its multipolar origin. We establish a one-to-one correspondence between the standard phenomenological non-Hermitian coupled-mode theory and multipolar models. The derived multipolar composition of the generated second-harmonic radiation from the AlGaAs nanodisk is then validated with full-wave numerical simulations. Back-action of the second-harmonic radiation onto the fundamental frequency is taken into account in the coupled nonlinear model with pump depletion. A hybrid metal-dielectric nanoantenna is proposed to augment the conversion efficiency up to tens of per cent due to increasing quality factors of the involved resonant states. Our findings delineate novel promising strategies in the design of functional elements for nonlinear nanophotonics applications.
Publisher: The Optical Society
Date: 12-12-2013
Publisher: Wiley
Date: 13-09-2019
DOI: 10.1111/ANAE.14838
Publisher: Wiley
Date: 23-10-2017
Publisher: Society for Neuroscience
Date: 25-07-2007
DOI: 10.1523/JNEUROSCI.1203-07.2007
Abstract: It is debated whether primary sensory neurons of the dorsal root ganglia increase the number in adult animals and, if so, whether the increase is attributable to postnatal neurogenesis or maturation of dormant, postmitotic precursors. Similar studies are lacking in the trigeminal ganglion (TG). Here we demonstrate by stereological methods that the number of neurons in the TG of adult male rats nearly doubles between the third and eighth months of age. The increase is mainly attributable to the addition of small, B-type neurons, with a smaller contribution of large, A-neurons. We looked for possible proliferative or maturation mechanisms that could explain this dramatic postnatal expansion in neuron number, using bromodeoxyuridine (BrdU) labeling, immunocytochemistry for neural precursor cell antigens, retrograde tracing identification of peripherally projecting neurons, and in vitro isolation of precursor cells from adult TG explant cultures. Cell proliferation identified months after an extended BrdU administration was sparse and essentially corresponded to glial cells. No BrdU-labeled cell took up the peripherally injected tracer, and only a negligible number coexpressed BrdU and the pan-neuronal tracer neuron-specific enolase. In contrast, a population of cells not recognizable as mature neurons in the TG and neighboring nerve expressed neuronal precursor antigens, and neural crest glioneuronal precursor cells were successfully isolated from adult TG explants. Our data suggest that a protracted maturation process persists in the TG that can be responsible for the neuronal addition found in the adult rat.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C8NR08034H
Abstract: Cylindrical vector beams with radial and azimuthal polarizations are used to study harmonic generation from in idual AlGaAs nanoantennas.
Publisher: American Society of Clinical Oncology (ASCO)
Date: 2021
DOI: 10.1200/JCO.20.01933
Abstract: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9% adjusted odds ratio [aOR], 0.62 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6% aOR, 0.53 95% CI, 0.36 to 0.76). Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks.
Publisher: Elsevier BV
Date: 06-2013
Publisher: Elsevier BV
Date: 10-2020
Publisher: American Physical Society (APS)
Date: 26-07-2023
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.ENVPOL.2015.08.015
Abstract: Polycyclic Aromatic Hydrocarbons (PAHs) represent a major class of toxic pollutants because of their carcinogenic and mutagenic characteristics. People living in urban areas are regularly exposed to PAHs because of abundance of their emission sources. Within this context, this study aimed to: (i) identify and quantify the levels of ambient PAHs in an urban environment (ii) evaluate their toxicity and (iii) identify their sources as well as the contribution of specific sources to measured concentrations. Sixteen PAHs were identified and quantified in air s les collected from Brisbane. Principal Component Analysis - Absolute Principal Component Scores (PCA-APCS) was used in order to conduct source apportionment of the measured PAHs. Vehicular emissions, natural gas combustion, petrol emissions and evaporative/unburned fuel were the sources identified contributing 56%, 21%, 15% and 8% of the total PAHs emissions, respectively, all of which need to be considered for any pollution control measures implemented in urban areas.
Publisher: American Physical Society (APS)
Date: 13-02-2015
Publisher: Walter de Gruyter GmbH
Date: 05-2023
Abstract: Symmetry-protected bound states in the continuum (SP-BICs) are one of the most intensively studied BICs. Typically, SP-BICs must be converted into quasi-BICs (QBICs) by breaking the unit cell’s symmetry so that they can be accessed by the external excitation. The symmetry-broken usually results in a varied resonance wavelength of QBICs which are also highly sensitive to the asymmetry parameters. In this work, we demonstrate that QBICs with a stable resonance wavelength can be realized by breaking translational symmetry in an all-dielectric metasurface. The unit cell of metasurface is made of a silicon nanodisk dimer. The Q-factor of QBICs is precisely tuned by changing the interspacing of two nanodisks while their resonance wavelength is quite stable against the interspacing. We also find that such BICs show weak dependence on the shape of the nanodisk. Multiple decompositions indicate that the toroidal dipole dominates this type of QBIC. The resonance wavelengths of QBICs can be tuned only by changing either the lattice constants or the radius of nanodisk. Finally, we present experimental demonstrations on such a QBIC with a stable resonance wavelength. The highest measured Q-factor of QBICs is . Our results may find promising applications in enhancing light–matter interaction.
Publisher: Wiley
Date: 04-2020
Publisher: SPIE-Intl Soc Optical Eng
Date: 15-06-2021
Publisher: MDPI AG
Date: 27-06-2018
DOI: 10.3390/MA11071091
Publisher: Springer Science and Business Media LLC
Date: 04-11-2019
DOI: 10.1038/S41598-019-52432-X
Abstract: Plasmonic metamaterial absorbers are particularly important in different applications such as photodetectors, microbolometers and solar cells. In this paper, we propose a tungsten boride (WB, a refractory ceramic) based broadband metamaterial absorber whose optical properties is numerically analyzed and experimentally characterized. We have also analyzed the damage characteristics of this absorber using a femtosecond laser and compared with an ordinary Au metamaterial absorber. We observe that WB has almost the double absorption bandwidth with absorption more than 90% over the spectral range of 950 to 1400 nm when compared with the Au counterpart. Furthermore, we show that Au metamaterial is damaged at the power of around 36.4 mW whereas WB metamaterial is not damaged at that power (WB has high Tammann temperature than Au)-however the atom of WB material was knocked off by the bombardment of a femtosecond laser.
Publisher: Springer Science and Business Media LLC
Date: 28-06-2022
DOI: 10.1038/S41377-022-00878-6
Abstract: An innovative time-varying metasurface has been reported to realise dual-channel data transmissions for light-to-microwave signal conversion. Such a novel technique is a remarkable step forward to realise full-spectrum networks for catering for the growing demand for wireless communications. Moreover, this technique enriches the functionalities of tunable metasurfaces and stimulates new information-oriented applications.
Publisher: American Chemical Society (ACS)
Date: 13-04-2023
Publisher: Springer Science and Business Media LLC
Date: 24-04-2019
DOI: 10.1038/S41598-019-42444-Y
Abstract: The development of a miniaturised device that provides efficient beam manipulation with high transmittance is extremely desirable for the broad range of applications including holography, metalens, and imaging. Recently, the potential of dielectric metasurfaces has been unleashed to efficiently manipulate the beam with full 2π-phase control by overlapping the electric and magnetic dipole resonances. However, in the visible range for available materials, it comes with the price of higher absorption that reduces efficiency. Here, we have considered dielectric amorphous silicon (a-Si) nanodisk and engineered them in such a way which provides minimal absorption loss in the visible range. We have experimentally demonstrated meta-deflector with high transmittance which operates in the visible wavelengths. The supercell of proposed meta-deflector consists of 15 amorphous silicon nanodisks numerically shows the transmission efficiency of 95% and deflection efficiency of 95% at operating wavelength of 715 nm. However, experimentally measured transmission and deflection efficiencies are 83% and 71%, respectively, having the experimental deflection angle of 8.40°. Nevertheless, by reducing the supercell length, the deflection angle can be controlled, and the value 15.50° was experimentally achieved using eight disks supercell. Our results suggest a new way to realise the highly transmittance metadevice with full 2π-phase control operating with the visible light which could be applicable in the imaging, metalens, holography, and display applications.
Publisher: American Chemical Society (ACS)
Date: 22-07-2022
DOI: 10.1021/ACS.NANOLETT.2C01349
Abstract: Resonant metasurfaces provide a unique platform for enhancing multiwave nonlinear interactions. However, the difficulties over mode matching and material transparency place significant challenges in the enhancement of these multiwave processes. Here we demonstrate efficient nonlinear sum-frequency generation (SFG) in multiresonant GaP metasurfaces based on guided-wave bound-state in the continuum resonances. The excitation of the metasurface by two near-infrared input beams generates strong SFG in the visible spectrum with a conversion efficiency of 2.5 × 10
Publisher: Oxford University Press (OUP)
Date: 25-09-2020
DOI: 10.1002/BJS.12050
Publisher: Elsevier BV
Date: 10-2021
Publisher: Wiley
Date: 04-08-2022
Abstract: The development of nanoscale optical sensors is desirable for a broad range of applications, including wearable medical‐diagnostics, biochemical detection, and environmental monitoring. Optical detection platforms based on resonant nanostructures are the golden standard for miniaturized footprint and high optical sensitivity. These sensors function by measuring a shift in resonance wavelength upon binding of analytes to their surface. However, such measurements are sensitive to intensity fluctuations of the illuminating source and its wavelength calibration, which limits their applicability. Here, a novel optical sensing concept based on diffraction measurements from resonant dielectric metagratings is proposed and experimentally demonstrated. It is shown that this approach enables the direct measurement of unknown analytes with enhanced sensitivity and without the need for intensity calibrations. The intensified sensitivity of this metagrating‐sensor is derived from combining the resonant phenomena of the nanostructures with the tailored diffraction from the metagrating, thereby providing the highest sensitivity demonstrated to date amongst grating‐based sensors. As a proof of concept, the metagrating‐sensor was validated using an antibody binding assay, achieving a femtomolar‐level limit of detection. Due to their high sensitivity and robust performance, the proposed metagrating sensors pave the way for novel miniaturized medical diagnostics and biosensing applications.
Publisher: Optica Publishing Group
Date: 26-04-2022
DOI: 10.1364/OL.453625
Abstract: We theoretically investigate boosting second-harmonic generation (SHG) of monolayer van der Waals crystals by employing flatband modes hosted by photonic moiré superlattices. Such a system with high quality factor and a monolayer crystal accommodated on the top of it, provides a unique opportunity to enhance and manipulate SHG emission. We show that employing a doubly resonant diagram on such a moiré superlattice system not only boosts the SHG, but also tunes the directional emission of the second-harmonic wave. Moreover, we demonstrate that a structured beam illumination could further boost SHG, with the phase structure retrieved through a two-beam second-harmonic interference configuration. These results suggest the flatband modes in moiré superlattice as a promising platform for boosting SHG with monolayer van der Waals crystals, offering new possibilities for developing compact nonlinear photonic devices.
Publisher: SPIE-Intl Soc Optical Eng
Date: 03-02-2021
Publisher: American Physical Society (APS)
Date: 12-09-2022
Publisher: Beilstein Institut
Date: 02-03-2018
DOI: 10.3762/BJNANO.9.71
Abstract: Background: Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) with intrinsically crystal inversion-symmetry breaking have shown many advanced optical properties. In particular, the valley polarization in 2D TMDCs that can be addressed optically has inspired new physical phenomena and great potential applications in valleytronics. Results: Here, we propose a TMDC–nanoantenna system that could effectively enhance and direct emission from the two valleys in TMDCs into diametrically opposite directions. By mimicking the emission from each valley of the monolayer of WSe 2 as a chiral point-dipole emitter, we demonstrate numerically that the emission from different valleys is directed into opposite directions when coupling to a double-bar plasmonic nanoantenna. The directionality derives from the interference between the dipole and quadrupole modes excited in the two bars, respectively. Thus, we could tune the emission direction from the proposed TMDC–nanoantenna system by tuning the pumping without changing the antenna structure. Furthermore, we discuss the general principles and the opportunities to improve the average performance of the nanoantenna structure. Conclusion: The scheme we propose here can potentially serve as an important component for valley-based applications, such as non-volatile information storage and processing.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2023
DOI: 10.1038/S41377-023-01078-6
Abstract: In the last decades, metasurfaces have attracted much attention because of their extraordinary light-scattering properties. However, their inherently static geometry is an obstacle to many applications where dynamic tunability in their optical behaviour is required. Currently, there is a quest to enable dynamic tuning of metasurface properties, particularly with fast tuning rate, large modulation by small electrical signals, solid state and programmable across multiple pixels. Here, we demonstrate electrically tunable metasurfaces driven by thermo-optic effect and flash-heating in silicon. We show a 9-fold change in transmission by V biasing voltage and the modulation rise-time of µs. Our device consists of a silicon hole array metasurface encapsulated by transparent conducting oxide as a localised heater. It allows for video frame rate optical switching over multiple pixels that can be electrically programmed. Some of the advantages of the proposed tuning method compared with other methods are the possibility to apply it for modulation in the visible and near-infrared region, large modulation depth, working at transmission regime, exhibiting low optical loss, low input voltage requirement, and operating with higher than video-rate switching speed. The device is furthermore compatible with modern electronic display technologies and could be ideal for personal electronic devices such as flat displays, virtual reality holography and light detection and ranging, where fast, solid-state and transparent optical switches are required.
Publisher: Wiley
Date: 10-10-2022
Abstract: Nanoresonators fabricated from low‐loss dielectrics with second‐order nonlinearity have emerged as a widespread platform for nonlinear frequency conversion at the nanoscale. However, a persisting challenge in this research is the generated complex far‐field polarization state of the upconverted light, which is a limiting factor in many applications. It will be highly desirable to generate uniform far‐field polarization states across all propagation directions, to control the polarization truly along the optical axis and to simultaneously be able to tune the polarization along the entire circumference of the Poincaré sphere by solely modifying the excitation polarization. Here, a nonlinear nanoresonator combining all these properties is theoretically proposed and experimentally demonstrated. At first, an analytical model connecting the induced multipolar content of a nanoresonator with a desired far‐field polarization is derived. Based on this, a nonlinear dielectric nanoresonator is designed to enable sum‐frequency generation (SFG) with highly pure and tuneable far‐field polarization states. In the experiment, the nanoresonators fabricated from the III‐V semiconductor gallium arsenide in (110)‐orientation are excited in an SFG scheme with in idually controllable excitation beams. The generation of highly uniform and tuneable far‐field polarization states is demonstrated by combining back‐focal plane measurements with Stokes polarimetry.
Publisher: Optica Publishing Group
Date: 16-02-2022
DOI: 10.1364/OL.452493
Abstract: A tip nanofocusing light field, with high electric-field intensity and nanoscale mode volume, can significantly improve nonlinear light scattering efficiency, thereby greatly promoting the development of strong-field nano-optics. Here, tip-enhanced four-wave mixing (FWM) is theoretically analyzed through two ultrafast radial vector beams internally illuminating an Ag-coated silica tip (ACST). Two femtosecond pulses, with radial electric vectors and pulse width of 100 fs, are adopted as excitation sources to illuminate the ACST. Degenerate tip-enhanced FWM ( ω FWM = 2 ω 1 − ω 2 ) with a nonlinear conversion efficiency of ∼10 −5 is achieved. The peak electric-field litude of the two pump pulses is 5 × 10 7 V/m, which is two orders of magnitude lower than that of the external excitation method. Further theoretical analysis shows that the conversion efficiency of the tip-enhanced FWM has strict frequency detuning dependence characteristics, and is closely related to the frequency response of the tip nanofocusing light field. This plasmonic tip provides an approach for enhancing nonlinear nano-optics, and may be used in the field of tip-based FWM nanoscopy.
Publisher: Wiley
Date: 10-05-2023
Abstract: Advanced sensing devices, highly sensitive, and reliable in detecting ultralow concentrations of circulating biomarkers, are extremely desirable and hold great promise for early diagnostics and real‐time progression monitoring of diseases. Nowadays, the most commonly used clinical methods for diagnosing biomarkers suffer from complicated procedures and being time consumption. Here, a chip‐based portable ultra‐sensitive THz metasensor is reported by exploring quasi‐bound states in the continuum (quasi‐BICs) and demonstrate its capability for sensing low‐concentration analytes. The designed metasensor is made of the designed split‐ring resonator metasurface which supports magnetic dipole quasi‐BIC combining functionalized gold nanoparticles (AuNPs) conjugated with the specific antibody. Attributed to the strong near‐field enhancement near the surface of the microstructure enabled by the quasi‐BICs, light‐analyte interactions are greatly enhanced, and thus the device's sensitivity is boosted significantly. The system sensitivity slope is up to 674 GHz/RIU, allowing for repeatable resolving detecting ultralow concentration of C‐reactive protein (CRP) and Serum Amyloid A (SAA), respectively, down to 1 pM. The results touch a range that cannot be achieved by ordinary immunological assays alone, offering a novel non‐destructive and rapid trace measured approach for next‐generation biomedical quantitative detection systems.
Publisher: AIP Publishing
Date: 08-2014
DOI: 10.1063/1.4893471
Abstract: We studied lensless imaging due to coherent backscattering in random media both theoretically and experimentally. The point spread function of the lensless imaging system was derived. Parameters such as the volume fraction of the scatterer in the random scattering medium, the diameter of the scatterer, the distance between the object to be imaged and the surface of the random scattering medium were optimized to improve the image contrast and resolution. Moreover, for complicated objects, high contrast and quality images were achieved through the high-order intensity correlation measurement on the image plane, which may propel this imaging technique to practical applications.
Publisher: American Chemical Society (ACS)
Date: 22-05-2017
DOI: 10.1021/ACS.NANOLETT.7B01488
Abstract: Nonlinear effects at the nanoscale are usually associated with the enhancement of electric fields in plasmonic structures. Recently emerged new platform for nanophotonics based on high-index dielectric nanoparticles utilizes optically induced magnetic response via multipolar Mie resonances and provides novel opportunities for nanoscale nonlinear optics. Here, we observe strong second-harmonic generation from AlGaAs nanoantennas driven by both electric and magnetic resonances. We distinguish experimentally the contribution of electric and magnetic nonlinear response by analyzing the structure of polarization states of vector beams in the second-harmonic radiation. We control continuously the transition between electric and magnetic nonlinearities by tuning polarization of the optical pump. Our results provide a direct observation of nonlinear optical magnetism through selective excitation of multipolar nonlinear modes in nanoantennas.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1NR04477J
Abstract: An ultra-sensitive THz metasensor is presented based on quasi-BIC Fano resonance, which can distinguish extremely dilute concentrations (nM) of solutions. It provides a nondestructive sensing approach for disease prevention and diagnosis.
Publisher: Springer Science and Business Media LLC
Date: 05-02-2020
Publisher: IOP Publishing
Date: 03-2022
Abstract: Tailoring optically resonant features in dielectric metasurfaces unveils a robust scheme to control electromagnetic near fields of light and thus to boost the nanoscale nonlinear light–matter interactions. Membrane metasurfaces offer unique possibilities for supporting multipolar resonances and meanwhile maintaining high mode volume for enhancing nonlinear frequency conversion. Here we design a silicon membrane metasurface consisting of dimer airy holes, as a versatile platform for generating four-wave mixing (FWM). We show that such a metasurface exhibits a multi-resonant feature, including a quasi bound state in the continuum (BIC) generated by the collective toroidal dipole mode excited in the designed subdiffractive periodic system. We show that via employing the BIC mode in the short-wave infrared (SWIR), together with other resonant enhanced electric near fields in the near-infrared (NIR) region, simultaneously, one can convert invisible SWIR light to visible light radiation with high efficiency, via FWM. We experimentally demonstrated a significant FWM emission enhancement from our metasurface, which leads to a conversion efficiency of 0.76 × 10 −6 using pump and signal beam peak intensities as low as 0.33 GW cm −2 and 0.17 GW cm −2 , respectively. Our results open new routes for enhancing nonlinear efficiencies for up-conversion processes.
Publisher: The Optical Society
Date: 04-11-2019
Publisher: SPIE-Intl Soc Optical Eng
Date: 21-06-2019
Publisher: The Optical Society
Date: 10-2019
Publisher: Springer Science and Business Media LLC
Date: 11-12-2020
DOI: 10.1007/S12028-020-01151-7
Abstract: Trauma-induced coagulopathy in patients with traumatic brain injury (TBI) is associated with high rates of complications, unfavourable outcomes and mortality. The mechanism of the development of TBI-associated coagulopathy is poorly understood. This analysis, embedded in the prospective, multi-centred, observational Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study, aimed to characterise the coagulopathy of TBI. Emphasis was placed on the acute phase following TBI, primary on subgroups of patients with abnormal coagulation profile within 4 h of admission, and the impact of pre-injury anticoagulant and/or antiplatelet therapy. In order to minimise confounding factors, patients with isolated TBI (iTBI) ( n = 598) were selected for this analysis. Haemostatic disorders were observed in approximately 20% of iTBI patients. In a subgroup analysis, patients with pre-injury anticoagulant and/or antiplatelet therapy had a twice exacerbated coagulation profile as likely as those without premedication. This was in turn associated with increased rates of mortality and unfavourable outcome post-injury. A multivariate analysis of iTBI patients without pre-injury anticoagulant therapy identified several independent risk factors for coagulopathy which were present at hospital admission. Glasgow Coma Scale (GCS) less than or equal to 8, base excess (BE) less than or equal to − 6, hypothermia and hypotension increased risk significantly. Consideration of these factors enables early prediction and risk stratification of acute coagulopathy after TBI, thus guiding clinical management.
Publisher: Springer Science and Business Media LLC
Date: 25-07-2018
DOI: 10.1038/S41377-018-0051-8
Abstract: We demonstrate that a dielectric anapole resonator on a metallic mirror can enhance the third harmonic emission by two orders of magnitude compared to a typical anapole resonator on an insulator substrate. By employing a gold mirror under a silicon nanodisk, we introduce a novel characteristic of the anapole mode through the spatial overlap of resonantly excited Cartesian electric and toroidal dipole modes. This is a remarkable improvement on the early demonstrations of the anapole mode in which the electric and toroidal modes interfere off-resonantly. Therefore, our system produces a significant near-field enhancement, facilitating the nonlinear process. Moreover, the mirror surface boosts the nonlinear emission via the free-charge oscillations within the interface, equivalent to producing a mirror image of the nonlinear source and the pump beneath the interface. We found that these improvements result in an extremely high experimentally obtained efficiency of 0.01%.
Publisher: Opto-Electronic Advances
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 15-07-2020
DOI: 10.1007/S11136-020-02583-6
Abstract: The Quality of Life after Brain Injury overall scale (QOLIBRI-OS) measures health-related quality of life (HRQoL) after traumatic brain injury (TBI). The aim of this study was to derive value sets for the QOLIBRI-OS in three European countries, which will allow calculation of utility scores for TBI health states. A QOLIBRI-OS value set was derived by using discrete choice experiments (DCEs) and visual analogue scales (VAS) in general population s les from the Netherlands, United Kingdom and Italy. A three-stage procedure was used: (1) A selection of health states, covering the entire spectrum of severity, was defined (2) General population s les performed the health state valuation task using a web-based survey with three VAS questions and an at random selection of sixteen DCEs (3) DCEs were analysed using a conditional logistic regression and were then anchored on the VAS data. Utility scores for QOLIBRI-OS health states were generated resulting in estimates for all potential health states. The questionnaire was completed by 13,623 respondents. The biggest weight increase for all attributes is seen from “slightly” to “not at all satisfied”, resulting in the largest impact on HRQoL. “Not at all satisfied with how brain is working” should receive the greatest weight in utility calculations in all three countries. By transforming the QOLIBRI-OS into utility scores, we enabled the application in economic evaluations and in summary measures of population health, which may be used to inform decision-makers on the best interventions and strategies for TBI patients.
Publisher: American Chemical Society (ACS)
Date: 15-12-2018
Publisher: American Chemical Society (ACS)
Date: 10-04-2019
Publisher: Springer Science and Business Media LLC
Date: 10-06-2023
DOI: 10.1038/S41467-023-39227-5
Abstract: High quality(Q) factor optical resonators are indispensable for many photonic devices. While very large Q-factors can be obtained theoretically in guided-mode settings, free-space implementations suffer from various limitations on the narrowest linewidth in real experiments. Here, we propose a simple strategy to enable ultrahigh-Q guided-mode resonances by introducing a patterned perturbation layer on top of a multilayer-waveguide system. We demonstrate that the associated Q-factors are inversely proportional to the perturbation squared while the resonant wavelength can be tuned through material or structural parameters. We experimentally demonstrate such high-Q resonances at telecom wavelengths by patterning a low-index layer on top of a 220 nm silicon on insulator substrate. The measurements show Q-factors up to 2.39 × 10 5 , comparable to the largest Q-factor obtained by topological engineering, while the resonant wavelength is tuned by varying the lattice constant of the top perturbation layer. Our results hold great promise for exciting applications like sensors and filters.
Publisher: Informa UK Limited
Date: 13-01-2022
Publisher: Elsevier BV
Date: 12-2021
DOI: 10.1016/J.BIOPHA.2021.112273
Abstract: Neurogenesis in the adult brain is well recognized and plays a critical role in the maintenance of brain function and homeostasis. However, whether neurogenesis also occurs in the adult peripheral nervous system remains unknown. Here, using sensory ganglia (dorsal root ganglia, DRGs) as a model, we show that neurogenesis also occurs in the peripheral nervous system, but in a manner different from that in the central nervous system. Satellite glial cells (SGCs) express the neuronal precursor markers Nestin, POU domain, class 4, transcription factor 1, and p75 pan-neurotrophin receptor. Following sciatic nerve injury, the suppression of endogenous proBDNF by proBDNF antibodies resulted in the transformation of proliferating SGCs into doublecortin-positive cells in the DRGs. Using purified SGCs migrating out from the DRGs, the inhibition of endogenous proBDNF promoted the conversion of SGCs into neuronal phenotypes in vitro. Our findings suggest that SGCs are neuronal precursors, and that proBDNF maintains the SGC phenotype. Furthermore, the suppression of proBDNF signaling is necessary for neuronal phenotype acquisition by SGCs. Thus, we propose that peripheral neurogenesis may occur via the direct conversion of SGCs into neurons, and that this process is negatively regulated by proBDNF.
Publisher: American Chemical Society (ACS)
Date: 16-02-2021
Publisher: American Chemical Society (ACS)
Date: 28-05-2019
DOI: 10.1021/ACS.NANOLETT.9B01112
Abstract: Second-harmonic generation (SHG) in resonant dielectric Mie-scattering nanoparticles has been hailed as a powerful platform for nonlinear light sources. While bulk-SHG is suppressed in elemental semiconductors, for ex le, silicon and germanium due to their centrosymmetry, the group of zincblende III-V compound semiconductors, especially (100)-grown AlGaAs and GaAs, have recently been presented as promising alternatives. However, major obstacles to push the technology toward practical applications are the limited control over directionality of the SH emission and especially zero forward/backward radiation, resulting from the peculiar nature of the second-order nonlinear susceptibility of this otherwise highly promising group of semiconductors. Furthermore, the generated SH signal for (100)-GaAs nanoparticles depends strongly on the polarization of the pump. In this work, we provide both theoretically and experimentally a solution to these problems by presenting the first SHG nanoantennas made from (111)-GaAs embedded in a low index material. These nanoantennas show superior forward directionality compared to their (100)-counterparts. Most importantly, based on the special symmetry of the crystalline structure, it is possible to manipulate the SHG radiation pattern of the nanoantennas by changing the pump polarization without affecting the linear properties and the total nonlinear conversion efficiency, hence paving the way for efficient and flexible nonlinear beam-shaping devices.
Publisher: Springer Science and Business Media LLC
Date: 16-11-2018
Publisher: Springer Science and Business Media LLC
Date: 21-03-2014
DOI: 10.1186/S13049-021-00930-1
Abstract: Prehospital care for patients with traumatic brain injury (TBI) varies with some emergency medical systems recommending direct transport of patients with moderate to severe TBI to hospitals with specialist neurotrauma care (SNCs). The aim of this study is to assess variation in levels of early secondary referral within European SNCs and to compare the outcomes of directly admitted and secondarily transferred patients. Patients with moderate and severe TBI (Glasgow Coma Scale 13) from the prospective European CENTER-TBI study were included in this study. All participating hospitals were specialist neuroscience centers. First, adjusted between-country differences were analysed using random effects logistic regression where early secondary referral was the dependent variable, and a random intercept for country was included. Second, the adjusted effect of early secondary referral on survival to hospital discharge and functional outcome [6 months Glasgow Outcome Scale Extended (GOSE)] was estimated using logistic and ordinal mixed effects models, respectively. A total of 1347 moderate/severe TBI patients from 53 SNCs in 18 European countries were included. Of these 1347 patients, 195 (14.5%) were admitted after early secondary referral. Secondarily referred moderate/severe TBI patients presented more often with a CT abnormality: mass lesion (52% vs. 34%), midline shift (54% vs. 36%) and acute subdural hematoma (77% vs. 65%). After adjusting for case-mix, there was a large European variation in early secondary referral, with a median OR of 1.69 between countries. Early secondary referral was not associated with functional outcome (adjusted OR 1.07, 95% CI 0.78–1.69), nor with survival at discharge (1.05, 0.58–1.90). Across Europe, substantial practice variation exists in the proportion of secondarily referred TBI patients at SNCs that is not explained by case mix. Within SNCs early secondary referral does not seem to impact functional outcome and survival after stabilisation in a non-specialised hospital. Future research should identify which patients with TBI truly benefit from direct transportation.
Publisher: Springer Science and Business Media LLC
Date: 10-09-2020
DOI: 10.1007/S00415-020-10174-1
Abstract: The original version of this article unfortunately contained a mistake.
Publisher: MDPI AG
Date: 12-07-2022
DOI: 10.3390/NANO12142384
Abstract: Nanopore sensors provide a unique platform to detect in idual nucleic acids, proteins, and other biomolecules without the need for fluorescent labeling or chemical modifications. Solid-state nanopores offer the potential to integrate nanopore sensing with other technologies such as field-effect transistors (FETs), optics, plasmonics, and microfluidics, thereby attracting attention to the development of commercial instruments for diagnostics and healthcare applications. Stable nanopores with ideal dimensions are particularly critical for nanopore sensors to be integrated into other sensing devices and provide a high signal-to-noise ratio. Nanopore fabrication, although having benefited largely from the development of sophisticated nanofabrication techniques, remains a challenge in terms of cost, time consumption and accessibility. One of the latest developed methods—controlled breakdown (CBD)—has made the nanopore technique broadly accessible, boosting the use of nanopore sensing in both fundamental research and biomedical applications. Many works have been developed to improve the efficiency and robustness of pore formation by CBD. However, nanopores formed by traditional CBD are randomly positioned in the membrane. To expand nanopore sensing to a wider biomedical application, controlling the localization of nanopores formed by CBD is essential. This article reviews the recent strategies to control the location of nanopores formed by CBD. We discuss the fundamental mechanism and the efforts of different approaches to confine the region of nanopore formation.
Publisher: Springer Science and Business Media LLC
Date: 06-09-2017
Publisher: Wiley
Date: 23-05-2019
Publisher: Opto-Electronic Advances
Date: 2023
Publisher: Elsevier BV
Date: 10-2020
Publisher: Springer Science and Business Media LLC
Date: 25-02-2020
Publisher: AIP Publishing
Date: 05-08-2021
DOI: 10.1063/5.0058768
Abstract: Optically resonant dielectric metasurfaces offer unique capability to fully control the wavefront, polarization, intensity, or spectral content of light based on the excitation and interference of different electric and magnetic Mie multipolar resonances. Recent advances of the wide accessibility in nanofabrication and nanotechnologies have led to a surge in the research field of high-quality functional optical metasurfaces, which can potentially replace or even outperform conventional optical components with ultra-thin features. Replacing conventional optical filtering components with metasurface technology offers remarkable advantages, including lower integration cost, ultra-thin compact configuration, easy combination with multiple functions, and less restriction on materials. Here, we propose and experimentally demonstrate a planar narrow bandpass filter based on the optical dielectric metasurface composed of Si nanoresonators in arrays. A broadband transmission spectral valley (around 200 nm) has been realized by combining electric and magnetic dipole resonances adjacent to each other. Meanwhile, we obtain a narrow-band transmission peak by exciting a high-quality leaky mode, which is formed by partially breaking a bound state in the continuum generated by the collective longitudinal magnetic dipole resonances in the metasurface. Owing to the in-plane inversion symmetry of our nanostructure, the radiation of this antisymmetric mode is inhibited at far field, manifesting itself a sharp Fano-shape peak in the spectrum. Our proposed metasurface-based filter shows a stable performance for oblique light incidence with small angles (within 10°). Our work implies many potential applications of nanoscale photonics devices, such as displays, spectroscopy, etc.
Publisher: Springer Science and Business Media LLC
Date: 16-07-2020
DOI: 10.1007/S00415-020-10022-2
Abstract: Fatigue is one of the most commonly reported subjective symptoms following traumatic brain injury (TBI). The aims were to assess frequency of fatigue over the first 6 months after TBI, and examine whether fatigue changes could be predicted by demographic characteristics, injury severity and comorbidities. Patients with acute TBI admitted to 65 trauma centers were enrolled in the study Collaborative European NeuroTrauma Effectiveness Research in TBI (CENTER-TBI). Subjective fatigue was measured by single item on the Rivermead Post-Concussion Symptoms Questionnaire (RPQ), administered at baseline, three and 6 months postinjury. Patients were categorized by clinical care pathway: admitted to an emergency room (ER), a ward (ADM) or an intensive care unit (ICU). Injury severity, preinjury somatic- and psychiatric conditions, depressive and sleep problems were registered at baseline. For prediction of fatigue changes, descriptive statistics and mixed effect logistic regression analysis are reported. Fatigue was experienced by 47% of patients at baseline, 48% at 3 months and 46% at 6 months. Patients admitted to ICU had a higher probability of experiencing fatigue than those in ER and ADM strata. Females and in iduals with lower age, higher education, more severe intracranial injury, preinjury somatic and psychiatric conditions, sleep disturbance and feeling depressed postinjury had a higher probability of fatigue. A high and stable frequency of fatigue was found during the first 6 months after TBI. Specific socio-demographic factors, comorbidities and injury severity characteristics were predictors of fatigue in this study.
Publisher: Beilstein Institut
Date: 06-02-2018
DOI: 10.3762/BJNANO.9.44
Abstract: Novel types of optical hybrid metasurfaces consist of metallic and dielectric elements are designed and proposed for controlling the interference between magnetic and electric modes of the system, in a reversible manner. By employing the thermo-optical effect of silicon and gold nanoantennas we demonstrate an active control on the excitation and interference between electric and magnetic modes, and subsequently, the Kerker condition, as a directive radiation pattern with zero backscattering, via temperature control as a versatile tool. This control allows precise tuning optical properties of the system and stimulating switchable sharp spectral Fano-like resonance. Furthermore, it is shown that by adjusting the intermediate distance between metallic and dielectric elements, opposite scattering directionalities are achievable in an arbitrary wavelength. Interestingly, this effect is shown to have a direct influence on nonlinear properties, too, where 10-fold enhancement in the intensity of third harmonic light can be obtained for this system, via heating. This hybrid metasurface can find a wide range of applications in slow light, nonlinear optics and bio-chemical sensing.
Publisher: SAGE Publications
Date: 07-08-2020
Abstract: Although rehabilitation is beneficial for in iduals with traumatic brain injury (TBI), a significant proportion of them do not receive adequate rehabilitation after acute care. Therefore, the goal of this prospective and multicenter study was to investigate predictors of access to rehabilitation in the year following injury in patients with TBI. Data from a large European study (CENTER-TBI), including TBIs of all severities between December 2014 and December 2017 were used (N = 4498 patients). Participants were dichotomized into those who had and those who did not have access to rehabilitation in the year following TBI. Potential predictors included sociodemographic factors, psychoactive substance use, preinjury medical history, injury-related factors, and factors related to medical care, complications, and discharge. In the year following traumatic injury, 31.4% of patients received rehabilitation services. Access to rehabilitation was positively and significantly predicted by female sex (odds ratio [OR] = 1.50), increased number of years of education completed (OR = 1.05), living in Northern (OR = 1.62 reference: Western Europe) or Southern Europe (OR = 1.74), lower prehospital Glasgow Coma Scale score (OR = 1.03), higher Injury Severity Score (OR = 1.01), intracranial (OR = 1.33) and extracranial (OR = 1.99) surgery, and extracranial complication (OR = 1.75). On contrast, significant negative predictors were lack of preinjury employment (OR = 0.80), living in Central and Eastern Europe (OR = 0.42), and admission to hospital ward (OR = 0.47 reference: admission to intensive care unit) or direct discharge from emergency room (OR = 0.24). Based on these findings, there is an urgent need to implement national and international guidelines and strategies for access to rehabilitation after TBI.
Location: United Kingdom of Great Britain and Northern Ireland
Location: Spain
No related grants have been discovered for Alfonso Lagares.