Raman Enhancement on a Broadband Meta-Surface

Cataloged from PDF version of article.Plasmonic metamaterials allow confinement of light to deep subwavelength dimensions, while allowing for the tailoring of dispersion and electromagnetic mode density to enhance specific photonic properties. Optical resonances of plasmonic molecules have been extensively investigated; however, benefits of strong coupling of dimers have been overlooked. Here, we construct a plasmonic meta-surface through coupling of diatomic plasmonic molecules which contain a heavy and light meta-atom. Presence and coupling of two distinct types of localized modes in the plasmonic molecule allow formation and engineering of a rich band structure in a seemingly simple and common geometry, resulting in a broadband and quasi-omni-directional meta-surface. Surface-enhanced Raman scattering benefits from the simultaneous presence of plasmonic resonances at the excitation and scattering frequencies, and by proper design of the band structure to satisfy this condition, highly repeatable and spatially uniform Raman enhancement is demonstrated. On the basis of calculations of the field enhancement distribution within a unit cell, spatial uniformity of the enhancement at the nanoscale is discussed. Raman scattering constitutes an example of nonlinear optical processes, where the wavelength conversion during scattering may be viewed as a photonic transition between the bands of the meta-material

Grating coupler integrated photodiodes for plasmon resonance based sensing

Cataloged from PDF version of article.In this work, we demonstrate an integrated sensor combining a grating-coupled plasmon resonance surface with a planar photodiode. Plasmon enhanced transmission is employed as a sensitive refractive index (RI) sensing mechanism. Enhanced transmission of light is monitored via the integrated photodiode by tuning the angle of incidence of a collimated beam near the sharp plasmon resonance condition. Slight changes of the effective refractive index (RI) shift the resonance angle, resulting in a change in the photocurrent. Owing to the planar sensing mechanism, the design permits a high areal density of sensing spots. In the design, absence of holes that facilitate resonant transmission of light, allows an easy-to-implement fabrication procedure and relative insensitivity to fabrication errors. Theoretical and experimental results agree well. An equivalent long-term RI noise of 6.3 x 10(-6) RIU/root Hz is obtained by using an 8 mW He-Ne laser, compared to a shot-noise limited theoretical sensitivity of 5.61 x 10(-9) RIU/root Hz. The device features full benefits of grating-coupled plasmon resonance, such as enhancement of sensitivity for non-zero azimuthal angle of incidence. Further sensitivity enhancement using balanced detection and optimal plasmon coupling conditions are discussed

Electrochemically tunable ultrafast optical response of graphene oxide

Cataloged from PDF version of article.We demonstrate reversible and irreversible changes in the ultrafast optical response of multilayer graphene oxide thin films upon electrical and optical stimulus. The reversible effects are due to electrochemical modification of graphene oxide, which allows tuning of the optical response by externally applied bias. Increasing the degree of reduction in graphene oxide causes excited state absorption to gradually switch to saturable absorption for shorter probe wavelengths. Spectral and temporal properties as well as the sign of the ultrafast response can be tuned either by changing the applied bias or exposing to high intensity femtosecond pulses. © 2011 American Institute of Physics

Cirugía retrógrada intrarrenal sin fluoroscopia: ¿es posible? Estudio prospectivo aleatorizado, una experiencia extraordinaria

Objectives: The aim of this study was to evaluate the role of the use of fluoroscopy in patients undergoing retrograde intrarenal surgery and the effect on surgical outcomes. Material and methods: The patients who were admitted to our center with the diagnosis of kidney stones were divided into 2 groups. In group 1, routine fluoroscopy was used in all cases (n: 58). In group 2, the same procedure was performed without fluoroscopy (n: 67) and the results of the 2 groups were compared. Results: There were no statistically significant differences between the 2 groups in terms of operation time, stone-free rate, complication rate, need for analgesic and re-treatment requirement and Visual Analogic Scale score. Conclusion: The use of fluoroscopy does not alter the complication frequency and stone-free rate. We think that the use of fluoroscopy is not mandatory in cases in which renal pelvis access is achieved especially with semirigid ureteroscopy and that unnecessary fluoroscopy increases radiation exposure. (C) 2019 AEU. Published by Elsevier Espana, S.L.U. All rights reserved

Distribution of bacterial pathogens and antimicrobial resistance in cows with clinical mastitis in a dairy farm, Türkiye

This study aimed to identify the pathogens causing clinical mastitis (CM) and their resistance levels to six common antimicrobials in a dairy farm in Turkey. A total of 973 CM milk samples were cultured and a Kirby-Bauer disc diffusion method was performed for antimicrobial susceptibility. While 64.0% (623/973) of CM samples were culture-positive, 36.0% (350/973) of CM samples yielded no growth. Escherichia coli was the most frequently isolated pathogen (36.3%), followed by coagulase-negative staphylococci (8.3%), Streptococcus dysgalactiae (7.3%), Staphylococcus aureus (3.1%), Streptococcus uberis (1.5%), Enterococcus spp. (1.4%), Mycoplasma spp. (1.4%), Streptococcus agalactiae (0.7%), and Corynebacterium spp. (0.4%). Antimicrobial resistance was higher (P > 0.01) to amoxicillin/clavulanic acid (AMC, 32.3%) than that to enrofloxacin (ENR, 23.4%), cefoperazone (CFP, 17.9%), cefquinome (CEQ, 17.7%), penicillin G (P, 15.2%), and gentamicin (CN, 3.6%) in culture-positive 642 isolates. For E. coli isolates, percentage of resistance to AMC, ENR, CFP, CEQ, P, and CN was 37.7, 30.6, 24.4, 23.2, 5.9, and 1.1%, respectively. Resistance to AMC (31.2%) and P (46.3%) was higher in CNS than Strep. dysgalactiae isolates (1.5% and 12.7%), respectively. Multidrug resistance was detected in 34 E. coli isolates (9.6%), 7 CNS isolates (8.6%), and 2 Strep. dysgalactiae (2.8%). In conclusion, the higher identification of E. coli demonstrated the higher risk of environmental microorganisms for CM in this study. Higher resistance to commonly used five of six antimicrobials showed the requirement of frequent bacteriological and antimicrobial susceptibility tests for CM. Thus, these implementations could increase treatment efficacy in cows and reduce antimicrobial resistance

The Farm, the city, and the emergence of social security

We study the social, demographic and economic origins of social security. The data for the U.S. and for a cross section of countries suggest that urbanization and industrialization are associated with the rise of social insurance. We describe an OLG model in which demographics, technology, and social security are linked together in a political economy equilibrium. In the model economy, there are two locations (sectors), the farm (agricultural) and the city (industrial) and the decision to migrate from rural to urban locations is endogenous and linked to productivity differences between the two locations and survival probabilities. Farmers rely on land inheritance for their old age and do not support a pay-as-you-go social security system. With structural change, people migrate to the city, the land loses its importance and support for social security arises. We show that a calibrated version of this economy, where social security taxes are determined by majority voting, is consistent with the historical transformation in the United States

Impact of Sm³⁺ and Er³⁺ Cations on the Structural, Optical, and Magnetic Traits of Spinel Cobalt Ferrite Nanoparticles: Comparison Investigation

In this study, we investigated a comparison of the structure, morphology, optic, and magnetic (room temperature (RT)) features of Er3+ and Sm3+ codoped CoFe2O4 (CoErSm) nanospinel ferrite (NSFs) (x ≤ 0.05) synthesized via hydrothermal (H-CoErSm NSFs) and sonochemical (S-CoErSm NSFs) approaches. The formation of all products via both synthesis methods has been validated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), along with energy-dispersive X-ray (EDX) and transmission electron microscopy (TEM) techniques. The single phase of the spinel structure (except for the Hyd sample with x = 0.03) was evidenced by XRD analysis. The DXRD (crystallite size) values of H-CoErSm and S-CoErSm NSFs are in the 10-14.7 and 10-16 nm ranges, respectively. TEM analysis presented the cubic morphology of all products. A UV-visible percent diffuse reflectance (DR %) study was performed on all products, and Eg (direct optical energy band gap) values varying in the 1.32-1.48 eV range were projected from the Tauc plots. The data of RT magnetization demonstrated that all prepared samples are ferromagnetic in nature. M-H data revealed that rising the contents of cosubstituent elements (Sm3+ and Er3+ ions) caused an increase in Ms (saturation magnetization) and Hc (coercive field) in comparison to pristine samples. Although concentration dependence is significant (x > 0.02), no strict regularity (roughly fluctuating) has been ruled out in Ms values for doped samples prepared via the hydrothermal method. However, sonochemically prepared samples demonstrated that Ms values increase with increasing x up to x = 0.04 and then decrease with the further rise in cosubstituent Sm3+ and Er3+ ions. The calculated values of Ms and Hc were found to be greater in H-CoErSm NSFs compared to those in S-CoErSm NSFs. The present investigation established that the distribution of cations and the variation in crystallite/particle sizes are efficient to control the intrinsic properties of all samples

Proteomic and Biological Analysis of the Effects of Metformin Senomorphics on the Mesenchymal Stromal Cells

Senotherapeutics are new drugs that can modulate senescence phenomena within tissues and reduce the onset of age-related pathologies. Senotherapeutics are divided into senolytics and senomorphics. The senolytics selectively kill senescent cells, while the senomorphics delay or block the onset of senescence. Metformin has been used to treat diabetes for several decades. Recently, it has been proposed that metformin may have anti-aging properties as it prevents DNA damage and inflammation. We evaluated the senomorphic effect of 6 weeks of therapeutic metformin treatment on the biology of human adipose mesenchymal stromal cells (MSCs). The study was combined with a proteome analysis of changes occurring in MSCs’ intracellular and secretome protein composition in order to identify molecular pathways associated with the observed biological phenomena. The metformin reduced the replicative senescence and cell death phenomena associated with prolonged in vitro cultivation. The continuous metformin supplementation delayed and/or reduced the impairment of MSC functions as evidenced by the presence of three specific pathways in metformin-treated samples: 1) the alpha-adrenergic signaling, which contributes to regulation of MSCs physiological secretory activity, 2) the signaling pathway associated with MSCs detoxification activity, and 3) the aspartate degradation pathway for optimal energy production. The senomorphic function of metformin seemed related to its reactive oxygen species (ROS) scavenging activity. In metformin-treated samples, the CEBPA, TP53 and USF1 transcription factors appeared to be involved in the regulation of several factors (SOD1, SOD2, CAT, GLRX, GSTP1) blocking ROS

Plasmonic absorbers for multispectral and broadband absorption

We present polarization dependent multispectral and broadband plasmonic absorbers in the visible spectrum. The spectral characteristics of these structures are tunable over a broad spectrum. Experimental results are verified with the FDTD and RCWA analysis methods. These structures are used as surface enhanced raman spectroscopy(SERS) substrates. Designed structures have resonances that span the Raman Stokes and excitation wavelength. Such structures can be used for energy, LED and other spectroscopy applications. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE)