Search

Surface‐enhanced Raman scattering (SERS) spectroscopy has renowned its fame for the ultra‐high sensitivity and single‐molecule detection ability, and listed as a fingerprint spectrum representative in various trace detection fields. Considerable efforts have been made by researchers to design high‐sensitive SERS‐active substrates ranging from noble metals to semiconductors. This review summarizes the fundamental theories for SERS technique, that is, the electromagnetic enhancement mechanism and chemical enhancement mechanism and the state‐of‐the‐art design strategies for noble metal and semiconductor substrates. It also sheds light on the effective approaches to improve the SERS activity for noble metal substrates, that is, tuning the localized surface plasmon resonance position, the assembling of hot spots, and precise controlling of nanogaps. Although charge transfer is considered as the main reason for the enhancement mechanism for semiconductors at the present stage, the underlying theoretical basis remains mysterious. This review summarized the critical points for SERS‐active substrates design and prospected the future development direction of SERS technology.

Polyanion-type sodium superionic conductor (NASICON) Na3V2(PO4)2F (NVOPF) is a promising cathode material for sodium ion batteries (SIBs). However, NVOPF shows relatively low specific capacity and ...

Newly-developed methods for utilizing performance surfaces—multivariate representations of the relationship between phenotype and functional performance—allow researchers to test hypotheses about adaptive landscapes and evolutionary diversification with explicit attention to functional factors. Here, information from performance surfaces of three turtle shell functions—shell strength, hydrodynamics, and self-righting—is used to test the hypothesis that turtle lineages transitioning from aquatic to terrestrial habitats show patterns of shell shape evolution consistent with decreased importance of hydrodynamic performance. Turtle shells are excellent model systems for evolutionary functional analysis. The evolution of terrestriality is an interesting test case for the efficacy of these methods because terrestrial turtles do not show a straightforward pattern of morphological convergence in shell shape: many terrestrial lineages show increased shell height, typically assumed to decrease hydrodynamic performance, but there are also several lineages where the evolution of terrestriality was accompanied by shell flattening. Performance surface analyses allow exploration of these complex patterns and explicit quantitative analysis of the functional implications of changes in shell shape. Ten lineages were examined. Nearly all terrestrial lineages, including those which experienced decreased shell height, are associated with morphological changes consistent with a decrease in the importance of shell hydrodynamics. This implies a common selective pattern across lineages showing divergent morphological patterns. Performance studies such as these hold great potential for integrating adaptive and performance data in macroevolutionary studies.

In this paper, a photonic crystal fiber sensor is proposed which have four-opening channels that support surface plasmon resonances. By detecting the optical spectrum of leakage from the fiber core to the four regions created on its periphery, the sensitivity of the sensor can be assessed. Gold is used as the plasmonic material in the infrared wavelength range on the Titanium oxide film which is used as a substrate layer to increase the coupling and adhesion. Influences of structural parameters on the sensor performance are investigated by the Finite Difference Element method. Sensitivities for refractive index of 1.34-1.44 for wavelength ranges (690-1500 nm) with maximum wavelength sensitivity of 25,600 nm / RIU and maximum amplitude sensitivity and 7367 ( RIU-1 ) and figure of merit (FOM) of 547 ( RIU-1 ) have been calculated. In addition to high sensitivity, great FOM value of this sensor is an important feature. This sensor can be used to identify chemicals and biomolecules.

A high performance sinusoidal grating-based surface plasmon resonance (SPR) biosensor is proposed. The angular interrogation method has been used to study the performance of the sensor. The sensitivity as well as the width of the SPR curves and reflective amplitude is considered for designing the sensor. Compared with the gold(Au)-based SPR sensor, we find that the silver(Ag)-based sensor has the better performance. Numerical simulations show that the sensitivity of the Ag-based sensor is 193.9°/RIU.

Noble metal nanoparticles (NPs) have been widely explored in surface-enhanced spectroscopies (SES) because of their ability to generate intense electric fields originating from the surface plasmon resonances. Particularly, coupled metallic NPs have attracted a lot of attentions in SES because they can generate much higher electric field enhancement than the single ones. In this study, two kinds of coupled structures, the dimer and the metal NP over the metal film (MNOMF), are examined using finite-difference time-domain method. Hot spots in these structures are optimized for high-performance SES. Hot spots in dimers are usually confined within small volumes, limiting the sensitivity and reproducibility of SES. In this study, we show that Au spiky NP dimers (SNPDs) can provide large-volume hot spots, arising from the synergistic effect of “lightning rod effect” in spiky NPs and the interparticle coupling. The “hot spots volume” (defined as the whole volumes of all the regions with electric field enhancement larger than 1E4) in T–T SNPD is almost 5 times and 7 times larger than in the sphere dimer and spike dimer with the same 2 nm gap, respectively. In addition, further increased “hot spots volume” is achieved in crossed T–T SNPD, being ~1.5 times of that in T–T SNPD. At the same time, the electric field enhancement (|E|^2/|E0|^2) in the tip-to-tip (T–T) SNPD with a 2 nm gap is as large as 1.21E6. The results indicate a strategy to obtain huge-volume hot spots with large electric field enhancement in dimers by adding a bulky core at one end of the spindly building blocks. We have shown SNPDs could provide hot spots with large volumes. Nevertheless, it is hard to fabricate SNPDs in experiments. Alternatively, spiky disk dimers (SDDs) on glass substrate may be fabricated using top-down lithography. We demonstrate crossed T-T SDD can generate much larger “hot spots volume” and much higher electric field enhancement than disk dimer. The results demonstrate the possibility to achieve large-volume hot spots in experiments. In both SNPDs and SDDs, two adjacent particles are coupled in lateral direction. In experiments, it is difficult to achieve precisely controlled small gaps in dimers along lateral direction and hence limiting the enhancement of electric fields. On the contrary, MNOMF which offers coupling in vertical direction can provide even sub-1 nm gap, exhibiting great potentials for SES. In this study, we demonstrate a method to optimize the hot spots in MNOMF by exciting the localized surface plasmon resonances (LSPRs) using the surface plasmon polaritons (SPPs). We find the largest electric field enhancement and the highest surface-enhanced fluorescence intensity are obtained when the SPPs of the metal film are excited. The results show that exciting LSPRs using SPPs can generate 1-3 orders higher electric field intensity than direct exciting the LSPRs using incidence from free space. The ultrahigh enhancement is attributed to the strong confinement of the SPP waves in the vertical direction. The drastically intensified electric fields generated from excitation of LSPRs using SPP waves are extremely essential for sensitive refractive index sensing, high-performance SES, and enhancing the efficiency of optoelectronic devices. DOCTOR OF PHILOSOPHY (MSE)

In this paper, first, the surface acoustic wave (SAW) propagation mode and a method of analyzing the propagation property are introduced briefly. Then, typical composite substrate structures that have been developed to obtain high-performance SAW devices are reviewed. Furthermore, the recent results obtained by the author and research colleagues on the propagation and resonance properties of leaky SAW (LSAW) and longitudinal-type LSAW on dissimilar-material bonded structures comprising a LiTaO3 (LT) or LiNbO3 thin plate with a thickness of less than 1 λ (λː wavelength) and a quartz substrate are described. The control of attenuation and the cause of large coupling factor of LSAWs by utilizing layered structures were also discussed. For the bonded 4 inch wafer of 36°YX-LT/AT90°X-quartz with a thin-plate thickness of 0.3 λ, an admittance ratio of 81 dB, a fractional bandwidth of 4.2%, and resonance and antiresonance factors of approximately 1500 with markedly improved properties compared with a single 36°YX-LT substrate were obtained experimentally at 2.2 GHz.

We demonstrate graphene oxide (GO)-decorated Ag dendritic nanostructures on a copper substrate for surface enhanced Raman scattering (SERS) applications. The Ag dendrites (AgD) were synthesized through a facile and low-cost galvanic replacement reaction of Ag nitrate solution and copper foils. The AgD/Cu was further decorated with GO by a dip-coating method. The GO-decorated AgD exhibited a much higher SERS activity in terms of sensitivity, signal-to-noise ratio and stability compared with non-decorated AgD, indicating that the GO/AgD/Cu substrates could be potentially useful for highly sensitive molecule detecting applications.

Recently, the use of artificial turf for soccer has become very popular. Although several cohort studies reported no clear differences for injury risk between artificial turfs and natural turf (Ful...

In this paper, we propose an adaptive triangular deployment algorithm that can adjust sensor distribution depending on the variation in communication performance in an underwater environment. To predict the distance between sensor nodes, a performance surface model is implemented by estimating the communication performance based on spatio-temporal environment factors affecting the communication performance of the underwater sensor node. Subsequently, the performance surface model is applied to the adaptive triangular deployment algorithm and is used to control the distance between nodes. Therefore, underwater wireless sensor networks deployed with adaptive triangular deployment algorithms can achieve a maximum connectivity rate with an optimal number of nodes.

We succeeded in fabrication of a high-performance surface optical coupler for coupling with $5-\mu m$ -MFD high numerical-aperture (HNA) optical fiber. The fabricated device showed the coupling loss of less than 2.4 dB and 0.5-dB-loss-bandwidth of over 220 nm for TE-polarization.

An efficient surface enhanced Raman scattering (SERS) substrate has been developed based on highly ordered arrays of graphene–isolated Au nanoparticle (G/AuNP). By combining the electromagnetic enhancement activity of AuNP arrays and unique physical/chemical properties of graphene, the G/AuNP arrays shows high performance in terms of sensitivity, signal-to-noise ratio and reproducibility. The average enhancement factor obtained from the G/AuNP arrays for rhodamine 6G probe molecules is over 10 7 . The maximum deviations of SERS intensities from 20 positions of a same SERS substrate are in the range of 4.74% to 6.89% and from 20 different substrates in various batches are in the range of 5.67% to 8.37%, depending on different vibration modes. As a practical application of this SERS system, we detect the adenosine concentration in human serum. The detection results show a good linear correlation between SERS intensity and adenosine concentration within the range of 2 to 250 nM. This work may open up new opportunities in developing the applications of SERS in biomedical diagnostics, biological sensing and other biotechnology.

In adaptive filtering, several algorithms are developed in the quest for greater convergence speed, mostly relying on second order statistics. Here we modify the Recursive Least Square (RLS) equations by using as performance surface a weighted sum of even error power. As a result, the equations turn out to be simple, elegant, while yielding faster convergence and preserving the computational cost when compared with the existing RLS algorithm. HighlightsIn this study, we propose a new recursive algorithm that optimizes a sum of the even powers of the error.In adaptive filtering, several algorithms were developed to improve convergence speed, but they rely mostly on second order statistics.This algorithm seems to be faster than usual recursive algorithms presents in the literature.

Maternal provisioning can have profound effects on offspring phenotypes, or maternal effects, especially early in life. One ubiquitous form of provisioning is in the makeup of egg. However, only a few studies examine the role of specific egg constituents in maternal effects, especially as they relate to maternal selection (a standardized selection gradient reflecting the covariance between maternal traits and offspring fitness). Here, we report on the evolutionary consequences of differences in maternal acquisition and allocation of amino acids to eggs. We manipulated acquisition by varying maternal diet (milkweed or sunflower) in the large milkweed bug, Oncopeltus fasciatus. Variation in allocation was detected by examining two source populations with different evolutionary histories and life-history response to sunflower as food. We measured amino acids composition in eggs in this 2 × 2 design and found significant effects of source population and maternal diet on egg and nymph mass and of source population, maternal diet, and their interaction on amino acid composition of eggs. We measured significant linear and quadratic maternal selection on offspring mass associated with variation in amino acid allocation. Visualizing the performance surface along the major axes of nonlinear selection and plotting the mean amino acid profile of eggs from each treatment onto the surface revealed a saddle-shaped fitness surface. While maternal selection appears to have influenced how females allocate amino acids, this maternal effect did not evolve equally in the two populations. Furthermore, none of the population means coincided with peak performance. Thus, we found that the composition of free amino acids in eggs was due to variation in both acquisition and allocation, which had significant fitness effects and created selection. However, although there can be an evolutionary response to novel food resources, females may be constrained from reaching phenotypic optima with regard to allocation of free amino acids.

Nanogaps or sharp protrusions has been proved useful for surface enhanced Raman scatting (SERS) in single-molecule sensing and a low cost method for fabricating SERS active substrate with these naonstructures is very important for practical applications of SERS in clinical or biological area. In this work, PMMA 3D nanostructures with sub-20nm ordered nanogap network and sharp tips are fabricated by high-fidelity replica molding. The morphology, water repellency property and Raman enhancement effect of the 3D nanostructures are characterized by SEM, water contact angle and SERS. The results show that the 3D nanostructure of rocket-like array has higher SERS enhancement factor (EF) than the 3D nanostructure of nano-lawn due to the ordered nanogaps, and both of them change the surface wettability of PMMA from hydrophilic to hydrophobic, especially for the 3D structure of nano-lawn.

Hot spots with a large electric field enhancement usually come in small volumes, limiting their applications in surface-enhanced spectroscopy. Using a finite-difference time-domain method, we demonstrate that spiky nanoparticle dimers (SNPD) can provide hot spots with both large electric field enhancement and large volumes because of the pronounced lightning rod effect of spiky nanoparticles. We find that the strongest electric fields lie in the gap region when SNPD is in a tip-to-tip (T-T) configuration. The enhancement of electric fields (|E|(2)/|E0|(2)) in T-T SNPD with a 2 nm gap can be as large as 1.21 × 10(6). And the hot spot volume in T-T SNPD is almost 7 times and 5 times larger than those in the spike dimer and sphere dimer with the same gap size of 2 nm, respectively. The hot spot volume in SNPD can be further improved by manipulating the arrangements of spiky nanoparticles, where crossed T-T SNPD provides the largest hot spot volume, which is 1.5 times that of T-T SNPD. Our results provide a strategy to obtain hot spots with both intense electric fields and large volume by adding a bulky core at one end of the spindly building block in dimers.

We report on the development of $\lambda\sim{4.7}~\mu{\rm m}$ continuous-wave (CW) operation of surface grating distributed feedback (DFB) quantum cascade lasers (QCLs). A high wall plug efficiency (WPE) of 7% is obtained at 15 $^{\circ}{\rm C}$ from a single facet producing over 0.85 W of CW output power. The threshold current density of DFB QCL is as low as 1.19 kA/cm at 15 $^{\circ}{\rm C}$ and 2.29 kA/cm at 90 $^{\circ}{\rm C}$ in CW mode. Single-mode operation with side mode suppression ratio above 25 dB is observed in the working temperature of 15 $^{\circ}$ –95 $^{\circ}{\rm C}$ .

This paper describes application of Sc-doped AlN (ScAlN) to wideband SAW devices in the 1 to 3 GHz range. First, it is shown theoretically that large SAW velocity and electromechanical coupling factor are simultaneously achievable when the ScAlN film is combined with a base substrate with extremely high acoustic wave velocities, such as diamond and SiC. Next, SAW delay lines are fabricated on the ScAlN/6H-SiC structure, and reasonable agreement between the theory and experiment is obtained. Finally, one-port SAW resonators are fabricated on the structure, and it is shown that high-performance is achievable in the 1 to 3 GHz range by use of the structure.

Medical Technologies National Conference (TIPTEKNO) -- OCT 27-29, 2016 -- Antalya, TURKEY WOS: 000455003600064 This paper investigate a fuzzy logic based high performance surface EMG classification algorithm for multifunctional upper limb prostheses. In this paper, we record 4 channels EMG data with surface electrodes from the forearm and aimed to recognize 8 different upper limb movements using heuristic fuzzy logic methods from these data. We use 50 surface EMG data for every function and evaluate the performance of this method.

Stern flaps have now been at sea for more than two decades on a variety of U.S. Navy (USN) and U.S. Coast Guard classes, including destroyers, cruisers, frigates, cutters, and patrol craft. Application of flaps to large-deck amphibious-type ships is a fairly recent extension of the technology. Ship performance improvements such as delivered power reduction and fuel savings, and maximum speed increases, have been proven during at-sea trials and are well documented (Cusanelli 2002). USN amphibious ships contain well decks, which are accessed through large folding stern gates. When open, the gates are supported by sizable structures, which are partially submerged and affixed to the transom. A new concept, the hydrodynamic and supportive structure for gated ship sterns, i.e., the amphibious stern flap, was developed and patented by the author (Cusanelli 2004a). This design combines a stern flap's hydrodynamic performance surface with the stern gate support structure. The Naval Surface Warfare Center, Carderock Division, has now designed and implemented this new type of integrated stern flap and gate support structure on several USN amphibious ship classes. USN ship design and research and development (R&D) programs have resulted in amphibious stern flaps being implemented as new construction items on two new Navy amphibious ship classes and one new subclass. The Fleet Readiness R&D Program has funded amphibious stern flap design, retrofit installations, and evaluation trials on two existing amphibious ships. Each amphibious stern flap design spiral, model-test series, optimization, full-scale implementation as well as performance benefits and fuel savings are discussed.

Detection of 2,4,6-trinitrotoluene (TNT) is an important environmental, security and health concern for the global community. TNT is a prime constituent of most of the landmines and bombs and is highly toxic and mutagenic. Various military and terrorist activities (e.g., manufacturing, waste discharge, testing and training) have resulted in extensive contamination of soil and ground water by TNT and its derivatives. Consequently, the development and application of new sensing techniques for detection and quantification of TNT has grown steadily over the years. Despite wide variety of analytical techniques, surface plasmon resonance (SPR) based immunosensors received great attention as a promising mean for TNT detection due to their advantages including high sensitivity, selectivity, good versatility and high throughput. This review explores the recent trend and advancements in immunochemical techniques for environmental monitoring and field detection of TNT. The advantages of the surface plasmon resonance as an optical signal transduction and indirect competitive immunoassay as the sensing principle are discussed with special emphasis on our investigations on TNT detection. A brief description on explosives, land-mines and the current detection techniques (bulk and trace detection) is also provided.

Alpine skiing is a popular winter sport. Athletes use their equipment on different courses that are covered with snow. From this perspective, better knowledge of snow conditions and the interaction between the skis and snow is fundamental, because performance and choices between different techniques are related to the interaction beteeen the athlete, the ski eqiuipment and the snow.

We consider the problem of finding the optimal specification of hyper-parameters in Support Vector Machines (SVMs). We sample the hyper-parameter space and then use Bezier curves to approximate the performance surface. This geometrical approach allows us to use the information provided by the surface and find optimal specification of hyper-parameters. Our results show that in most cases the specification found by the proposed algorithm is very close to actual optimal point(s). The results suggest that our algorithm can serve as a framework for hyper-parameter search, which is precise and automatic.

A new strategy for achieving high performance SERS was proposed by using the dummy molecular imprinting technique. The obtained core–shell composite can effectively improve the signal-to-noise ratio and the veracity of trace analysis in SERS detection.

Techniques available in the literature to enhance the robustness of generic model control (GMC) are reviewed. We show that none of these techniques utilize a rigorous analysis of the process-model mismatch. This paper presents GMC from the geometric perspective in order to analyze the effect of process uncertainties in the closed-loop response. The geometric approach defines a performance surface for the closed-loop response with no model error. When the model is not perfect, the system leaves the surface, making the response diffrent from the reference. A technique based on sliding mode control, called sliding generic model control, is developed here to take into account the process uncertainties and to keep the system close to the GMC performance surface.

Label-free immunoassay systems have the advantages of procedural simplicity and a low construction cost of surfaces for immunosensing. When label-free immunoassay systems are considered, the nonspecific adsorption of unwanted materials should be eliminated unless it aids in the detection of error. PEG is well-known as a blocking agent for the prevention of the adsorption of nonspecific binding materials when coimmobilized with ligands for targets such as antibodies and oligonucleotides. The construction strategy for PEG/ligand coimmobilized surfaces is an important point in the preparation of a high-performance assays because the physiological condition of the ligand depends strongly on its interaction with the PEG chain. In this report, we investigate the interaction between thrombin and a thrombin-binding aptamer (TBA) on a PEG/TBA coimmobilized surface by using a shear horizontal surface acoustic wave (SAW) sensor. The thrombin-TBA binding property shows remarkable differences with changes in the PEG density and the distance from the gold surface to the aptamer.