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In this paper, we demonstrate the first example of phonon-assisted hot luminescence (PAHL) emission from silicon (Si) spheres (diameter > 100nm) without using the plasmonic effect or quantum confinement effect. Instead, we excite the hot luminescence of Si by a strong thin-film-cavity-enhanced magnetic dipole resonance. The thin-film cavity (80 nm SiO2/Ag) shows a strong co-enhancement with the magnetic dipole resonance of Si sphere (diameter = 120 nm). The concentrated electromagnetic fields induce significant light–matter interaction. Our Si sphere coupled with a thin-film cavity achieves a 10-fold field enhancement relative to the Si sphere without an enhancement substrate. Furthermore, we experimentally use cavity-enhanced magnetic dipole resonance to a 50-fold enhancement in PAHL. The measured internal quantum efficiency for the visible light emitted from the Si spheres was approximately 2.4%. Furthermore, we demonstrate the tunability of emission peaks merely by adjusting the sizes of Si spheres using thermal oxidation and etching processes. For comparison, we calculated the peak wavelength (λ peak) sensitivities (Δλ peak/ΔDiameter) of Si spheres and Si QDs through Mie theory and effective mass approximation, respectively. The predicated peak sensitivities of the Si spheres ranged from 1.3 to 3.2; they were much more controllable than those of the Si QDs (200–400). Thus, the peak wavelengths of the PAHL of the Si spheres could be modulated and controlled much more precisely and readily than that of the Si QDs. With the tunability and strong electromagnetic field confinement, the cavity-enhanced magnetic dipole resonance appears to have great potential in the development of all-optical processing based on Si photonics.

Purpose The purpose of the study is to test the longitudinal efficacy of a mHealth intervention (Intergenerational Mobile Technology Opportunities Program, IMTOP) for older type 2 diabetes mellitus (T2DM) patients in rural Taiwan. Few mHealth programs targeted rural older adults and the longitudinal effects are unknown. Methods Ninety-seven T2DM patients aged 55+ were recruited from an outpatient in Hualien, Taiwan. The intervention comprised 8-week technology and diabetes self-management training and 4-week technical support. College student tutors facilitated T2DM patients to learn technology. Participants used a diabetes self-management app to track health behaviors. Outcomes measured at baseline and at 4 and 8 months including patient-reported self-care behaviors, T2DM symptoms, clinical outcomes, health resource utilization, and medical expenditure. Linear mixed-effect regressions of repeated measures were conducted for each outcome. Results At 4 months, improvements in self-care behaviors were reported in diet, exercise, smoking, and blood glucose testing. Patients paid less endocrinology clinic visits, spent less on endocrinology medications, and improvements in fasting blood glucose and total cholesterol were observed. At 8 months, the statistical significance of improvements in diet and smoking were maintained, and the averaged endocrinology clinic visits remained less than baseline. However, more frequent occurrence of diabetes symptoms were reported at both follow-ups. Conclusions: IMTOP had lasting effects on diet and decreased smoking behavior, clinic visits, and medication costs over 8 months. Self-monitoring through an app increased awareness and may explain the increased reporting of diabetes symptoms. IMTOP is a promising model for promoting T2DM self-management in rural areas.

Large-area graphene is commonly prepared through chemical vapor deposition (CVD); in situ and nondestructive methods for its characterization are desirable. In this paper, we demonstrate a practical method—exploiting magnetic dipole resonance and coupling effects—with which the Raman signals of graphene on copper (Cu) foil can be directly, faithfully, and greatly enhanced. The magnetic dipole resonance of a silicon nanoparticle (SiNP) can effectively couple its electromagnetic field with the Cu foil to induce an enormous electric field located solely at the position of the SiNP on the graphene. The coupled electromagnetic field can lead to hot spots of high electric field intensity (E2/E02 = 123.2) within the graphene. Even when we positioned only a few SiNPs upon the graphene/Cu foil, we obtained a Raman signal enhancement (ca. 206 times) much greater than that of graphene transferred onto a 300 nm oxide film (ca. 12 times). From a series of experiments comparing the Raman signals of graphene before and ...

In this study we developed a method, using a simple two-layer nanocavity structure, to significantly enhance light outcoupling from two-dimensional (2D) materials. Because the surface electric fields (E-fields) of the nanocavities were enhanced greatly over ultrabroadband regimes, the excitation of various 2D materials with laser light and their Raman and photoluminescence (PL) light emissions were all enhanced dramatically while maintaining band-to-band ratios and peak positions precisely. At the same time, the optical visibility of the 2D materials was also enhanced significantly over a broad spectral regime. Using a single type of Ag/SiO2 nanocavity structure, we obtained a 475-fold, equal enhancement in the intensities of the main Raman peaks of single-layer graphene (SLG) and more than a 350-fold increase in the intensities of both the Raman and PL signals of single-layer tungsten disulfide (WS2). Notably, the light outcouplings of these 2D materials were enhanced dramatically without any spectral di...

In this study we developed an approach to identify the surface polarity of silicon carbide (SiC) by using an excitation laser possessing a photon energy (2.33 eV) much lower than the band gap of 4H-SiC (3.30 eV). By gradually attenuating the intensity of the excitation laser, the effective depth that the laser could generate Raman signals could eventually be limited to within the ultrashallow region of the SiC wafer. Through three-dimensional finite-difference-time-domain (3D-FDTD) simulations, we found that the depth of the high electric field region could be limited from several micrometers below the surface to the near-surface region of 4H-SiC, merely by attenuating the power of the incident laser. Experimentally, we observed a clear trend in the Raman peak intensity ratio of the signals at 210 and 203 cm–1 in the FTA mode: the intensity ratio of the Si face was always higher than that of the C face regardless of the measurement position on the 4H-SiC wafer. Even through the carrier concentrations in t...

We developed a nanocavity structure to enhance light outcoupling from different two-dimensional (2D) materials. The Raman and photoluminescence (PL) light emissions from 2D materials were enhanced dramatically while maintaining band-to-band ratios and peak positions precisely.

In this study, an eco-friendly and ultrasensitive paper substrate is developed for surface-enhanced Raman scattering (SERS) with performance approaching single molecule detection. By exploiting the laser-induced photothermal effect, paper fibrils with hybrid micro- and nanostructures can facilitate the formation of highly dense metal nanoparticles (NPs) after a single shot of laser illumination. Metal films deposited on the paper substrates feature discontinuous morphologies, with the fragments acting as multiple nucleation sites. Because thermal conductivity is low on the broken films and the underlying paper fibrils, the incident energy is absorbed efficiently. Moreover, the quasi-three-dimensional distribution of NPs on the SERS paper greatly enhances the SERS signals within the effective collection volume of a Raman microscope. As a result of the large number of highly effective hot spots and the condensation effect, the hydrophobic SERS paper provides SERS signals with stable and uniform reproducibility throughout the detection area. The limits of detection when using the paper substrates reach the attomolar (10(-18) M) level, thereby approaching single molecule detection.

In this study, we found that the large area of electromagnetic field hot zone induced through magnetic dipole resonance of metal-free structures can greatly enhance Raman scattering signals. The magnetic resonant nanocavities, based on high-refractive-index silicon nanoparticles (SiNPs), were designed to resonate at the wavelength of the excitation laser of the Raman system. The well-dispersed SiNPs that were not closely packed displayed significant magnetic dipole resonance and gave a Raman enhancement per unit volume of 59 347. The hot zones of intense electric field were generated not only within the nonmetallic NPs but also around them, even within the underlying substrate. We observed experimentally that gallium nitride (GaN) and silicon carbide (SiC) surfaces presenting very few SiNPs (coverage: 50%) Raman signals. In contrast, the Raman signals of the underlying substrates were not enhanced by gold nanoparticles (AuNPs), even though these NPs displayed a localized surface plasmon resonance (LSPR) phenomenon. A comparison of the areas of the electric field hot zones (E 2 > 10) generated by SiNPs undergoing magnetic dipole resonance with the electric field hot spots (E 2 > 10) generated by AuNPs undergoing LSPR revealed that the former was approximately 70 times that of the latter. More noteworthily, the electromagnetic field hot zone generated from the SiNP is able to extend into the surrounding and underlying media. Relative to metallic NPs undergoing LSPR, these nonmetallic NPs displaying magnetic dipole resonance were more effective at enhancing the Raman scattering signals from analytes that were underlying, or even far away from, them. This application of magnetic dipole resonance in metal-free structures appears to have great potential for use in developing next-generation techniques for Raman enhancement.

In this study, we develop an ultrasensitive nanoparticle (NP)-film caliper that functions with high resolution (angstrom scale) in response to both the dimensions and refractive index of the spacer sandwiched between the NPs and the film. The anisotropy of the plasmonic gap mode in the NP-film caliper can be characterized readily using spectroscopic ellipsometry (SE) without the need for further optical modeling. To the best of our knowledge, this paper is the first to report the use of SE to study the plasmonic gap modes in NP-film calipers and to demonstrate that SE is a robust and convenient method for analyzing NP-film calipers. The high sensitivity of this system originates from the plasmonic gap mode in the NP-film caliper, induced by electromagnetic coupling between the NPs and the film. The refractometric sensitivity of this NP-film caliper reaches up to 314 nm per RIU, which is superior to those of other NP-based sensors. The NP-film caliper also provides high dimensional resolution, down to the angstrom scale. In this study, the shift in wavelength in response to the change in gap spacing is approximately 9 nm Å(-1). Taking advantage of the ultrasensitivity of this NP-film caliper, we develop a platform for discriminating among thiol-containing amino acids.

In this paper, we describe a high-reflectance liquid mirror prepared from densely packed silver nanoparticles (AgNPs) of two different sizes. We controlled the particle size during the synthetic process by controlling the temperature. Varying the concentration of the ligand also allowed us to optimize the arrangement of the AgNPs to achieve liquid mirrors exhibiting high specular reflectance. Scanning electron microscopy and atomic force microscopy confirmed that the particles of the liquid mirror were well-packed with an interparticle distance of merely 2 nm; thus, the interstices and surface roughness of the NPs were effectively minimized. As a result of decreased scattering loss, the reflectance in the shorter wavelength regime was increased effectively. The AgNP film was also sufficiently thick to reflect the light in the longer wavelength regime. In addition, we used three-dimensional finite-difference time domain simulations and experimental measurements to investigate the relationship between the localized surface plasmon resonance (LSPR) and the specular reflection of the liquid mirrors. By changing the packing density of the AgNPs, we found that the LSPR effect could yield either a specular reflection peak or dip at the LSPR wavelengths in the reflection spectra of the liquid mirrors. Relative to previously reported liquid mirrors, the reflectance of our system is obviously much greater, especially in the shorter wavelength regime. The average reflectance in the range from 400 to 1000 nm could reach 77%, comparable with that of mercury-based liquid mirrors.

Background Intertrochanteric fractures in elderly patients are common and normally caused by low-energy injuries, such as falls. The favored treatment method is closed reduction with internal fixation using plate or nail systems. In general, the severity of an intertrochanteric fracture is one of key factors that affects the success rate of fixation. However, the factors that affect the severity of intertrochanteric fractures in elderly patients are rarely reported in the literature. In this prospective study, several possible factors were investigated. Methods The bone mineral densities (BMD) of 48 elderly patients (≥ 65 years) with intertrochanteric fractures due to low-energy injuries were compared with the BMDs of 48 elderly persons without hip fractures. Both groups were composed of people of similar ages and male-to-female ratios. Furthermore, in the patients with fractures, BMD, body mass index (BMI), body weight, and body height were compared between patients with nonsevere (intact lesser trochanter; 14 patients) and severe (displaced lesser trochanter or reverse obliquity fractures; 34 patients) intertrochanteric fractures. Results Patients with intertrochanteric fractures had significantly lower BMDs compared with persons without hip fractures to the lesser trochanter, total hip area, femoral neck, or greater trochanter ( p = 0.001, Conclusion Elderly patients with intertrochanteric fractures have lower BMDs than persons without hip fractures. However, the severity of intertrochanteric fractures cannot be predicted by local BMD, BMI, body weight, or body height.

An investigation of speciated mercury transformation with the addition of hydrogen bromide (HBr) at elevated temperatures was conducted in a slipstream reactor with real flue gas atmospheres. A real flue gas atmosphere is composed of bituminous coal (with high sulfur and high chlorine contents) and Powder River Basin (PRB) coal (with lower sulfur and chlorine contents). The average sulfur, chlorine, and mercury contents in the tested bituminous coal were 1.31% and 1328 and 0.11 ppm and 0.61% and 170 and 0.08 ppm, respectively, for tested PRB coal. The average CaO, Fe2O3, and loss on ignition in collected fly ash contents of tested bituminous coal were 1.71, 17.51, and 7.13% and 22.95, 4.91, and 0.64%, respectively, for tested PRB coal. The different contents of coal chlorine, CaO, and Fe2O3 in fly ash can be attributed to the different mercury speciations at baseline tests for these two coals in this study. The addition of HBr concentrations into the flue gas was controlled in the 3−15 ppm range. Semi-con...

In this study we demonstrated that the improvement of detection capability of cadmium sulfide (CdS) photoconductors in the ultraviolet (UV) regime is much larger than that in the visible regime, suggesting that the deep UV laser treated CdS devices are very suitable for low-light detection in the UV regime. In addition, we determined that a nanocrystallized CdS photoconductor can behave as a picowatt-sensitive detector in the UV regime after ultra-shallow-region crystallization of the CdS film upon a single shot from a KrF laser. The strategy proposed herein appears to have great potential for application in the development of CdS photoconductors for picowatt-level detection of UV light with low power consumption.

We have used a direct imprint-in-metal method that is cheap and rapid to prepare incident angle-tuned, broadband, ultrahigh-sensitivity plasmonic antennas from nanoparticles (NPs) and imprinted metal mirrors. By changing the angle of incidence, the nanoparticle-imprinted mirror antennas (NIMAs) exhibited broadband electromagnetic enhancement from the visible to the near-infrared (NIR) regime, making them suitable for use as surface-enhanced Raman scattering (SERS)-active substrates. Unlike other SERS-active substrates that feature various structures with different periods or morphologies, the NIMAs achieved broadband electromagnetic enhancement from single configurations. The enhancement of the electric field intensity in the NIMAs originated from coupling between the localized surface plasmon resonance of the NPs and the periodic structure-excited surface plasmon resonance (SPR) of the imprinted mirror. Moreover, the coupling wavelengths could be modulated because the SPR wavelength was readily tuned by changing the angle of the incident light. Herein, we demonstrate that such NIMAs are robust substrates for visible and NIR surface-enhanced resonance Raman scattering under multiple laser lines (532, 633, and 785 nm) of excitation. In addition, we have found that NIMAs are ultrasensitive SERS-active substrates that can detect analytes (e.g., rhodamine 6G) at concentrations as low as 10(-15) M.

In this study, we demonstrated that the improvement of detection capability of cadmium sulfide (CdS) photoconductors in the ultraviolet (UV) regime is much larger than that in the visible regime, suggesting that the deep UV laser-treated CdS devices are very suitable for low-light detection in the UV regime. We determined that a nanocrystallized CdS photoconductor can behave as a picowatt-sensitive detector in the UV regime after ultra-shallow-region crystallization of the CdS film upon a single shot from a KrF laser. Photoluminescence and Raman spectra revealed that laser treatment increased the degree of crystallization of the CdS and led to the effective removal of defects in the region of a few tens nanometers beneath the surface of CdS, confirming the result by the transmission electron microscopy (TEM) images. Optical simulations suggested that UV light was almost completely absorbed in the shallow region beneath the surface of the CdS films, consistent with the observed region that underwent major crystal structure transformation. Accordingly, we noted a dramatic enhancement in responsivity of the CdS devices in the UV regime. Under a low bias voltage (1 mV), the treated CdS device provided a high responsivity of 74.7 A W(-1) and a detectivity of 1.0×10(14) Jones under illumination with a power density of 1.9 nW cm(-2). Even when the power of the UV irradiation on the device was only 3.5 pW, the device exhibited extremely high responsivity (7.3×10(5) A W(-1)) and detectivity (3.5×10(16) Jones) under a bias voltage of 1 V. Therefore, the strategy proposed in this study appears to have great potential for application in the development of CdS photoconductors for picowatt-level detection of UV light with low power consumption.

In this study, we developed a new method-based on laser-induced jets of nanoparticles (NPs) and air drag forces-to select the particle size of NP arrays. First, the incident wavelength of an excimer laser was varied to ensure good photo-to-thermal energy conversion efficiency. We then exploited air drag forces to select NPs with sizes ranging from 5 to 50 nm at different captured distances. Controlling the jet distances allowed us to finely tune the localized surface plasmon resonance (LSPR) wavelength. The shifting range of the LSPR wavelengths of the corresponding NP arrays prepared using the laser-induced jet was wider than that of a single NP or an NP dimer. We further calculated the relationship between the air drag force and the diameter of the NPs to provide good control over the mean NP size (capture size ≧ 300 μm) by varying the capture distance. Laser-induced jets of NPs could also be used to fabricate NP arrays on a variety of substrates, including Si, glass, plastic, and paper. This method has the attractive features of rapid, large-area preparation in an ambient environment, no need for further thermal annealing treatment, ready control over mean particle size, and high selectivity in the positioning of NP arrays. Finally, we used this method to prepare large NP arrays for acting hot spots on surface-enhanced Raman scattering-active substrates, and 10(-12) M R6G can be detected. Besides, we also prepare small NP arrays to act as metal catalysts for constructing low-reflection, broadband light trapping nanostructures on Si substrates.

In this study we describe a low-cost cadmium sulfide (CdS) photoconductor that behaves as a highly sensitive and rapidly responding detector toward low-intensity light. Through the observation of TEM images and analysis of micro-Raman spectra, the degree of crystallization of CdS films increased and their dislocation defects were removed effectively after treatment with several shots from a KrF excimer laser. Such laser treatment of CdS photoconductors could be conducted in air and completed within a few seconds. At a very low bias voltage of 1 mV, the laser-treated CdS device provided a record high responsivity of 7200 A W−1 and a detectivity of 1015 Jones. In addition, at a normal bias voltage of 1 V, it displayed an extremely high responsivity of 7 × 106 A W−1 and a detectivity of 6 × 1016 Jones. The measured response time of the laser-annealed CdS device from the dark to illumination at 10−2 fW μm−2 was only 40 ms—much faster than the shutter speed or exposure time required for a professional digital camera for such low-light image detection. Accordingly, KrF laser annealing is a simple and rapid process that can significantly enhance the low-light detection properties of CdS, a commercial photoconductor. Our strategy proposed herein appears to hold great potential for ultralow-light image detection with ultralow power consumption.