Extra Enhancement Research Articles

Enhanced Surface-Enhanced Raman Scattering (SERS) Sensitivity by the Self-Assembly of Silver Nanoparticles (Ag NPs) Laminated on Polydimethylsiloxane (PDMS)

Herein, a transparent and reproducible substrate, fabricated using polydimethylsiloxane (PDMS) laminated with self-assembled Ag nanoparticles (Ag NPs), was employed as a universal surface-enhanced Raman scattering (SERS) substrate for the detection of targets with various matrices. The Ag NPs were assembled in a two-dimensional manner via a self-assembly technique. Due to the electrostatic interaction between the Ag NPs, the reproducibility of the assembly was ensured by the fixed density of the assembled Ag NPs at saturated assembly states. The assembled pattern and plasmon resonance of the Ag NPs were well preserved during the molding and curing of PDMS. As a result, the Ag NP laminated PDMS film exhibited a SERS effect to the adsorbed p-aminothiophenol comparable to that of the assembled Ag NPs on a glass slide. Extra SERS enhancement was achieved by construction of a Ag (PDMS)/molecule/Ag (glass) configuration due to the electromagnetic coupling between the Ag NPs. The Raman scattering of 4-mercaptobenzoic acid and benzotriazole modified on the surfaces of a smooth Au electrode and copper foil, respectively, was detected with the aid of the Ag NP-laminated PDMS film. Furthermore, malachite green dispersed in a KBr solid matrix was quantitatively determined with a detection limit of 0.5 μg/g. It is suggested that the SERS enhancement and consequential SERS detection sensitivity of the target molecules may be further maximized by adjusting the distance between the target molecules and the Ag NPs laminated on the PDMS film.

Microfluidics-Driven Fabrication of a Low Cost and Ultrasensitive SERS-Based Paper Biosensor

Surface-enhanced Raman scattering (SERS) spectroscopy stands out due to its sensitivity, selectivity, and multiplex ability. The development of ready-to-use, simple, and low-cost SERS substrates is one of the main challenges of the field. In this paper, the intrinsic reproducibility of microfluidics technology was used for the fabrication of self-assembled nanoparticle structures over a paper film. The paper SERS substrates were fabricated by assembling anisotropic particles, gold nanostars (GNSs), and nanorods (NRs) onto paper to offer an extra enhancement to reach ultra-sensitive detection limits. A polydimethylsiloxane PDMS-paper hybrid device was used to control the drying kinetics of the nanoparticles over the paper substrate. This method allowed a high reproducibility and homogeneity of the fabrication of SERS substrates that reach limits of detection down to the picomolar range. This simple and low-cost fabrication of a paper-based sensing device was tested for the discrimination of different cell lineages.

Direct detection of DNA using 3D surface enhanced Raman scattering hotspot matrix.

Silver nanoparticles (AgNPs) are evaporatively self-assembled into the 3D surface enhanced Raman scattering (SERS) hotspot matrix with the assistant of glycerol to improve the spectral reproducibility in direct DNA detection. AgNPs and DNA in the glycerol-stabilized 3D SERS hotspot matrix are found to form flexible sandwich structures through electrostatic interaction where neighboring AgNPs create uniform and homogeneous localized surface plasmon resonance coupling environments for central DNA. Nearly two orders of magnitude extra SERS enhancement, more stable peak frequency and narrower peak full width at half maximum can therefore be obtained in DNA SERS spectra, which ensures highly stable and reproducible SERS signals in direct detection of both single strand DNA and double strand DNA utilizing the 3D SERS hotspot matrix. By normalizing the SERS spectra using phosphate backbone as internal standard, identification of single base variation in oligonucleotides, determination of DNA hybridization events and recognition of chemical modification on bases (hexanethiol-capped at 5' end) have been demonstrated experimentally. This proposed 3D SERS hotspot matrix opens a novel perspective in manipulating plasmonic nanoparticles to construct SERS platforms and would make the surface enhanced Raman spectroscopy a more practical and reliable tool in direct DNA detection.

Bayesian estimation for quantum sensing in the absence of single-shot detection

Quantum information protocols, such as quantum error correction and quantum phase estimation, have been widely used to enhance the performance of quantum sensors. While these protocols have relied on single-shot detection, in most practical applications only an averaged readout is available, as in the case of room-temperature sensing with the electron spin associated with a nitrogen-vacancy center in diamond. Here, we theoretically investigate the application of the quantum phase estimation algorithm for high dynamic-range magnetometry, in the case where single-shot readout is not available. We show that, even in this case, Bayesian estimation provides a natural way to use the available information in an efficient way. We apply Bayesian analysis to achieve an optimized sensing protocol for estimating a time-independent magnetic field with a single electron spin associated to a nitrogen-vacancy center at room temperature and show that this protocol improves the sensitivity over previous protocols by more than a factor of 3. Moreover, we show that an extra enhancement can be achieved by considering the timing information in the detector clicks.

Mechanical response of the fly ash cenospheres/polyurethane syntactic foams fabricated through infiltration process

Abstract In this paper, the low-cost syntactic foams were prepared by incorporating the fly ash cenospheres into the rigid polyurethane foams. The empirical relations were developed for predicting the porosity of the syntactic foams. Effects of the density and cenospheres size on the mechanical response of both the plain foams and aluminum foils reinforced foams were examined under quasi-static compression. The results show that, when the relative density was below 0.29, the cenospheres size marginally influenced the mechanical properties. When the relative density was above 0.29, the plain foams containing larger cenospheres exhibited better mechanical performances. For the reinforced foams, however, the mechanical properties were significantly improved by using smaller cenospheres. Moreover, the extra mechanical enhancement apart from the addition of the aluminum honeycombs was only effective for the composites containing smaller cenospheres. The reinforcing mechanisms of these composites were identified by the comparison of the mechanical properties and the analysis on their deformation behaviors. It demonstrated that the remarkable reinforcement was dominated by the failure pattern transition in the plain foams. This study may help to develop a comprehensive use of the fly ash cenospheres in civil engineering as functional materials.

The stability enhancement factor beyond eight-electron shell closure in thiacalix[4]arene-protected silver clusters.

We report the synthesis and structures of two 34-atom metal nanoclusters, namely [Ag34(BTCA)3(C[triple bond, length as m-dash]CBu t )9(tfa)4(CH3OH)3]SbF6 and [AuAg33(BTCA)3(C[triple bond, length as m-dash]CBu t )9(tfa)4(CH3OH)3]SbF6, where H4BTCA is p-tert-butylthiacalix[4]arene and tfa is trifluoroacetate. Their compositions and structures have been determined by single-crystal X-ray structural analysis and ESI-MS. The cationic cluster consists of a centered icosahedron M@Ag12 (M = Ag or Au) core that is surrounded by 21 peripheral silver atoms. Surrounding protection is provided by four kinds of ligands, including three BTCA, nine t BuC[triple bond, length as m-dash]C, four tfa, and three methanol solvent ligands. It was found that the Ag5@BTCA μ5-coordination motif of thiacalixarene is critical for high stability of the title clusters, and extra stability enhancement can be achieved by doping a gold atom at the center of the silver cluster. This work suggests that coordination saturation should be taken into account in addition to electronic and geometric factors for analyzing metal nanocluster stabilities.

Ultrasonic Power to Enhance Limestone Dissolution in the Wet Flue Gas Desulfurization Process. Modeling and Results from Stepwise Titration Experiments

The goal of this work is to assess the application of ultrasonic power to the reactive dissolution of limestone particles in an acidic environment; this would represent a novel method for improving wet Flue Gas Desulfurization industrial systems. In this study a stepwise titration method is utilized; experiments were done by using different particle size distributions with and without the application of ultrasound. The use of ultrasonic power sensibly affected the reaction rate of limestone and its dissolution; a major difference could be observed when samples from the Wolica region in Poland were studied. In this case, the overall dissolution rate was found to increase by more than 70%. The reactive dissolution of limestone does not follow the same mathematical model when sonication is in effect; in this case, an extra Ultrasonic Enhancement Constant was introduced. It was demonstrated that the dissolution is proportional to an Effective Reaction Surface and, therefore, surface interactions should also be taken into consideration. For this purpose, a study is presented here on the Z-potential and electrophoretic mobility of limestone samples measured in aqueous dispersions by means of Laser Doppler Micro-Electrophoresis.

Rheological Evolution of Ti-Bearing Slag with Different Volume Fractions of TiN

The effect of the volume fraction of TiN (0 to 4.27 vol pct) on the rheological behaviors of Ti-bearing slag, including the viscosity and the constitutive equation, was investigated using a Brookfield rheometer at 1773 K. With the increasing TiN, the viscosity and the shear stress increased substantially, and the slag is converted from Newtonian to non-Newtonian. When the slag samples were dispersed with TiN (1.00 to 4.27 vol pct), the measured viscosities were greater than those estimated by the Einstein–Roscoe equation, and the complex internal structure was suggested to be responsible for the extra enhancement of the viscosity beyond that caused by TiN itself. The viscosity curves of the slag samples containing TiN (1.00 to 4.27 vol pct) were divided into three regions depending on the critical shear rate and the initial shear rate. In the Newtonian region, the apparent volume fraction of TiN was defined and used to develop a semiempirical model based on the Einstein–Roscoe equation to describe the viscosity. In the two non-Newtonian regions, the shear rate, the yield stress, and the viscosity differences between the non-Newtonians regions and the Newtonian regions were applied in developing the viscosity models.

Green synthesis of multi-dimensional plasmonic coupling structures: Graphene oxide gapped gold nanostars for highly intensified surface enhanced Raman scattering

Graphene-mediated surface-enhanced Raman scattering (SERS) substrates are currently explored for ultrasensitive detection and expected to provide uniform SERS response by the virtue of graphene and plasmonic metal nanostructures. Here, we integrated graphene oxide (GO) and anisotropic metal nanostructures to create a novel multiple coupling system, in which ultrathin GO as nanospacer was sandwiched between two layers of closely packed gold nanostars (AuNSts). The sandwiched hybrid was prepared through alternative loading of AuNSts and graphene oxide (GO) film via filtration and spin-coating methods in the absence of any polymer stabilizer or organic linkage agent. The morphologies and plasmon resonance of AuNSts could be tuned by simply adjusting the synthesis parameters. Due to the multi-dimensional plasmonic coupling in horizontally and vertically patterned AuNSts, extra chemical enhancement and outstanding molecule harvesting capability from GO interlayer, the as-prepared AuNSt-GO-AuNSt sandwich structures manifested ultrahigh sensitivity and excellent reproducibility (the signal variations <6%). A detection limit of rhodamine-6G (R6G) as low as 10−13 M and a high enhancement factor of 6.64 × 107 were achieved. Particularly, the AuNSt-GO-AuNSt system was applied to detect erythrosine B and chrysoidin down to 10−9 M as well as offer spectroscopic identification in complicated solutions, indicating great potential practical applications for the rapid and sensitive on-site monitoring, especially for food and environmental safety.

Neural Character-level Dependency Parsing for Chinese

This paper presents a truly full character-level neural dependency parser together with a newly released character-level dependency treebank for Chinese, which has suffered a lot from the dilemma of defining word or not to model character interactions. Integrating full character-level dependencies with character embedding and human annotated character-level part-of-speech and dependency labels for the first time, we show an extra performance enhancement from the evaluation on Chinese Penn Treebank and SJTU (Shanghai Jiao Tong University) Chinese Character Dependency Treebank and the potential of better understanding deeper structure of Chinese sentences.

A Robust Authentication Scheme for Client-Server Architecture With Provable Security Analysis

Client-server computing is the analytical development of compatible programming with significant supposition and the detachment of a massive program into its fundamental parts ("modules"), which can create the chance for extra enhancement, inconsiderable improvement, and prominent maintainability. In client-server computing, total extensive modules don't need to be accomplished within the similar memory space totally but can execute independently on a suitable hardware and software platform according to their behavior. The user authentication is the dominant constraint for client-server computing that limits the illegitimate right of entry into the main workstation. This research is mainly focused on the design of a robust authentication scheme for client-server architecture computing. It carries some additional features like security, virtualization, user's programs security, individuality supervision, integrity, control access to server and authentication. The proposed background also delivers the characteristic supervision, mutual authentication, and establishment of secure session key among users and the remote server.

A Millimetre-Wave Cuboid Solid Immersion Lens with Intensity-Enhanced Amplitude Mask Apodization

Photonic jet is a narrow, highly intensive, weak-diverging beam propagating into a background medium and can be produced by a cuboid solid immersion lens (SIL) in both transmission and reflection modes. Amplitude mask apodization is an optical method to further improve the spatial resolution of a SIL imaging system via reduction of waist size of photonic jet, but always leading to intensity loss due to central masking of the incoming plane wave. In this letter, we report a particularly sized millimetre-wave cuboid SIL with the intensity-enhanced amplitude mask apodization for the first time. It is able to simultaneously deliver extra intensity enhancement and waist narrowing to the produced photonic jet. Both numerical simulation and experimental verification of the intensity-enhanced apodization effect are demonstrated using a copper-masked Teflon cuboid SIL with 22-mm side length under radiation of a plane wave with 8-mm wavelength. Peak intensity enhancement and the lateral resolution of the optical system increase by about 36.0% and 36.4% in this approach, respectively.

RETRACTED: A solar cell endows the Surface-enhanced Raman scattering substrate with extra enhancement

RETRACTED: A solar cell endows the Surface-enhanced Raman scattering substrate with extra enhancement

Atomic-Scale Lightning Rod Effect in Plasmonic Picocavities: A Classical View to a Quantum Effect.

Plasmonic gaps are known to produce nanoscale localization and enhancement of optical fields, providing small effective mode volumes of about a few hundred nm3. Atomistic quantum calculations based on time-dependent density functional theory reveal the effect of subnanometric localization of electromagnetic fields due to the presence of atomic-scale features at the interfaces of plasmonic gaps. Using a classical model, we explain this as a nonresonant lightning rod effect at the atomic scale that produces an extra enhancement over that of the plasmonic background. The near-field distribution of atomic-scale hot spots around atomic features is robust against dynamical screening and spill-out effects and follows the potential landscape determined by the electron density around the atomic sites. A detailed comparison of the field distribution around atomic hot spots from full quantum atomistic calculations and from the local classical approach considering the geometrical profile of the atoms' electronic density validates the use of a classical framework to determine the effective mode volume in these extreme subnanometric optical cavities. This finding is of practical importance for the community of surface-enhanced molecular spectroscopy and quantum nanophotonics, as it provides an adequate description of the local electromagnetic fields around atomic-scale features with use of simplified classical methods.

Secondary flows and extra heat transfer enhancement of ribbed surfaces with jet impingement

ABSTRACTPrevious experiments recognize that substantial heat transfer augmentation is achieved by adding ribbed turbulators after jet impingement with cross flow present. To address fundamental working mechanisms, conjugate CFD simulations are employed for ribs, jet impingement, and their combinations. Flow characteristics and drawbacks for the individual and combined enhancement techniques are highlighted. New analysis on the coupled design arrangement reveals that the counter-rotating vortices generated by the jet flow can energize inter-rib recirculating vortices and promote span-wise convection. With an optimal design combination arrangement, extra heat transfer benefit is achieved beyond that associated with simple superposition of rib and jet impingement techniques.

Significant color space blue-shift of green OLED emitter with sustaining lifetime and substantial efficiency enhancement

In this study, we demonstrate that by embedding a plasmonic coupling metal layer beneath the active layer of an organic light-emitting diode, the resultant device is capable of inducing significant blue shifts in CIE color space coordinates of emitting light from the green emitting material without compromising the lifetime of the parent material. The implemented device consists of multilayers of organic emitting materials sandwiched by two thin metal layers to form a metal-dielectric-metal (MDM) cavity-like structure. The original green emission with CIE coordinates of (0.22, 0.56) was significantly color space blue-shifted to CIE coordinates of (0.10, 0.53). The MDM device exhibits an efficiency of 62 cd/A at a luminance of 1000 cd/m2, which represents a two-fold enhancement of current efficiency. Moreover, the spectral peak intensity is 4.3 times higher than that in a conventional device, which is much higher than that expected for an optical microcavity model, suggesting that the Purcell effect resulting from the coupling of surface plasmon waves may contribute to the extra enhancement of emission intensity.

Liquid Crystal Leaky-Wave Antennas With Dispersion Sensitivity Enhancement

A novel design, fabrication, and packaging technology is proposed for liquid crystal (LC)-based beam-scanning leaky-wave antennas (LWAs). Different from conventional ones, extra dispersion sensitivity enhancement (DSE) components are introduced to increase the slope of effective phase constant versus frequency of LWAs and, hence, the beam scanning range. CST MW Studio software package is used to validate the design method. It is shown that, by adding the DSE components, the electrical beam scanning range is extended by more than 56% in the Ku satellite communication band, where good impedance matching and balanced condition are kept for both extreme tuning states of LCs. Prototypes of the designed LC-composite right/left-handed LWAs with and without the DSE components are fabricated and measured. The fabrication methodology incorporating printed circuit board and precision metal processing technology ensures the mechanical stability, flexible design, perfect packaging, and low cost. Finally, the feature-selective validation technique validates that the measured and simulated results are in good agreement.

The asymmetric CFT landscape in with extended supersymmetry

We study asymmetric simple‐current extensions of Gepner models in dimensions with at least eight supercharges in the right‐moving sector. The models obtained in an extensive stochastic computer search belong to a small number of different classes. These classes can be categorized as dimensional reductions, asymmetric orbifolds with , extra gauge enhancement and as coming from the super Higgs‐effect. Models in the latter class are particularly interesting, as they may correspond to non‐geometric flux compactifications.

An enhanced degree of charge transfer in dye-sensitized solar cells with a ZnO-TiO2/N3/Ag structure as revealed by surface-enhanced Raman scattering.

A number of recent studies have focused on improving the performance of dye-sensitized solar cells (DSSCs). Cells with a ZnO-TiO2/N3/Ag structure have attracted particular attention because of their excellent power conversion efficiencies. Using a dendritic crystal ZnO-TiO2 composite semiconductor and Ag in conjunction leads to different charge-transfer (CT) processes, and this is the main theoretical basis for the improvement of DSSC performances. Thus, in the present study, TiO2/N3, ZnO/N3, ZnO-TiO2/N3, TiO2/N3/Ag, ZnO/N3/Ag, and ZnO-TiO2/N3/Ag assemblies have been fabricated and their CT processes have been monitored by using surface-enhanced Raman scattering (SERS) spectra, with particular focus on the differences caused by the synergistic effect of the ZnO-TiO2 component. The dye loading capacity of the dendritic crystal ZnO-TiO2 is much larger than that of TiO2. There are extra enhancements in the SERS intensity and degree of CT (ρCT) in ZnO-TiO2/N3 compared to ZnO + TiO2/N3 (based on a simulation curve for the physically mixed TiO2 and ZnO semiconductors) with 476.5 nm excitation due to the synergistic effect of the ZnO-TiO2 component. And these enhancements in ZnO-TiO2/N3/Ag compared to ZnO + TiO2/N3/Ag appear with 476.5 and 532 nm excitation, which are particularly large with 532 nm excitation. Accordingly, the participation of Ag in this synergistic effect can reduce its energy threshold, which will make it easier to appear. Finally, to rationalize these extra enhancements, the models describing the CT mechanism have been proposed. Thus, the use of the dendritic crystal ZnO-TiO2 composite semiconductor in the semiconductor/N3/Ag system can improve the adsorption capacity of N3 compared to that with TiO2. Meanwhile, the synergistic effect of ZnO-TiO2 and Ag can promote the CT process, demonstrating that ZnO-TiO2/N3/Ag is an excellent structure for DSSCs.

Theory of SERS enhancement: general discussion.

Rohit Chikkaraddy opened the discussion of the Introductory Lecture: Regarding quantifying the chemical enhancement, you showed a systematic change in the SERS enhancement for halide substituted molecules due to charge transfer from the metal. Is the extra enhancement due to an inherent increase in the Raman cross-section of the molecule? How do you go about referencing, as the charge transfer changes the vibrational frequency?