New Perspective on Planar Inductive Sensors: Radio-Frequency Refractometry for Highly Sensitive Quantification of Magnetic Nanoparticles.

We demonstrate how resonant planar coils may be used as sensors to detect and quantify magnetic nanoparticles reliably. A coil's resonant frequency depends on the adjacent materials' magnetic permeability and electric permittivity. A small number of nanoparticles dispersed on a supporting matrix on top of a planar coil circuit may thus be quantified. Such nanoparticle detection has application detection to create new devices to assess biomedicine, food quality assurance, and environmental control challenges. We developed a mathematical model for the inductive sensor response at radio frequencies to obtain the nanoparticles' mass from the self-resonance frequency of the coil. In the model, the calibration parameters only depend on the refraction index of the material around the coil, not on the separate magnetic permeability and electric permittivity. The model compares favourably with three-dimensional electromagnetic simulations and independent experimental measurements. The sensor can be scaled and automated in portable devices to measure small quantities of nanoparticles at a low cost. The resonant sensor combined with the mathematical model is a significant improvement over simple inductive sensors, which operate at smaller frequencies and do not have the required sensitivity, and oscillator-based inductive sensors, which focus on just magnetic permeability.

High Luminous Efficacy Phosphor-Converted Mass-Produced White LEDs Achieved by AlN Prebuffer and Transitional-Refraction-Index Patterned Sapphire Substrate.

Constant advance in improving the luminous efficacy (ηL) of nitride-based light-emitting diodes (LEDs) plays a critical role for saving measurable amounts of energy. Further development is motivated to approach the efficiency limit for this material system while reducing the costs. In this work, strategies of using thin AlN prebuffer and transitional-refraction-index patterned sapphire substrate (TPSS) were proposed, which pushed up the efficiency of white LEDs (WLEDs). The AlN prebuffer was obtained through physical vapor deposition (PVD) method and TPSS was fabricated by dry-etched periodic silica arrays covered on sapphire. Devices in mass production confirmed that PVD AlN prebuffer was able to improve the light output power (φe) of blue LEDs (BLEDs) by 2.53% while increasing the productivity by ~8% through shortening the growth time. Additionally, BLEDs on TPSS exhibited an enhanced top ηext of 5.65% in contrast to BLEDs on the conventional PSS through Monte Carlo ray-tracing simulation. Consequently, φe of BLEDs was experimentally enhanced by 10% at an injected current density (Jin) of 40 A/cm2. A peak ηL of 295.2 lm/W at a Jin of 0.9 A/cm2 and the representative ηL of 282.4 lm/W at a Jin of 5.6 A/cm2 for phosphor-converted WLEDs were achieved at a correlated color temperature of 4592 K.

Tunable Terahertz Metamaterial with Electromagnetically Induced Transparency Characteristic for Sensing Application.

We present and demonstrate a MEMS-based tunable terahertz metamaterial (TTM) composed of inner triadius and outer electric split-ring resonator (eSRR) structures. With the aim to explore the electromagnetic responses of TTM device, different geometrical parameters are compared and discussed to optimize the suitable TTM design, including the length, radius, and height of TTM device. The height of triadius structure could be changed by using MEMS technique to perform active tunability. TTM shows the polarization-dependent and electromagnetic induced transparency (EIT) characteristics owing to the eSRR configuration. The electromagnetic responses of TTM exhibit tunable characteristics in resonance, polarization-dependent, and electromagnetically induced transparency (EIT). By properly tailoring the length and height of the inner triadius structure and the radius of the outer eSRR structure, the corresponding resonance tuning range reaches 0.32 THz. In addition to the above optical characteristics of TTM, we further investigate its potential application in a refraction index sensor. TTM is exposed on the surrounding ambient with different refraction indexes. The corresponding key sensing performances, such as figure of merit (FOM), sensitivity (S), and quality factor (Q-factor) values, are calculated and discussed, respectively. The calculated sensitivity of TTM is 0.379 THz/RIU, while the average values of Q-factor and FOM are 66.01 and 63.83, respectively. These characteristics indicate that the presented MEMS-based TTM device could be widely used in tunable filters, perfect absorbers, high-efficient environmental sensors, and optical switches applications for THz-wave optoelectronics.

Complex dielectric function and opto-electronic characterization using VEELS for the lead-free BCZT electro-ceramic perovskite.

The current work presents the complex dielectric function and the opto-electronic properties of lead-free Ba0.8Ca0.2Ti0.9Zr0.1O3 (BCZT) electro-ceramic, derived from valence electron energy loss spectroscopy, in transmission electron microscopy (VEELS-TEM). A single tetragonal perovskite phase, with P4mm space group, was determined by Rietveld refinement of the x-ray diffraction pattern. The VEELS-TEM experiment scanned the energy interval from 0-50 eV. The spectroscopic analysis started with the chemical identification of the atoms that conforms the BCZT solid-solution. Bulk and surface plasmons were located at 27.2 eV and 12.9 eV, respectively in the energy loss function. Complex dielectric function was obtained using Kramers-Kronig analysis from the Gatan Microscopy Suite software. Dielectric constant was calculated from the real part of the complex dielectric function, while the inter-band transitions were identified in the joint density of states function. The refraction index n and the extinction coefficient k, as a function of energy, were obtained from the complex dielectric function. The bandgap energy was determined using a polynomial fit in the optical absorption coefficient plot with an Eg = 3.2 eV.

The effect of refractive index of fillers and polymer matrix on translucency and color matching of dental resin composite.

OBJECTIVE: When restorative resin composites absorb light from the surrounding tooth structures, it creates a color-match, which is known as 'a chameleon effect'. In this study, series of co-monomer mixtures were prepared with an increasing refraction index (RI) and mixed with glass fillers. The aim of this study was to optimize the mismatch of RI of resin/fillers to create the chameleon effect. MATERIALS AND METHODS: BisGMA/TEGDMA resins were prepared with seven different mix fractions from 20 to 80%. Two different series (A&B) of submicron (Ø 0.7 µm) silanized fillers (70 wt%) (A: Schott RI = 1.53, B: Esschem RI = 1.54) were mixed with resins (30 wt%). Disc-shaped specimens (1 mm thickness, Ø10 mm) for each composite combination (n = 3) were prepared and light cured for 20 s. Commercial resin composite (OmniChroma, Tokuyama Dental) was used as control. The translucency parameter (TP) was measured using a spectrophotometer. The color matching abilities of the experimental composites were visually analyzed. Data were statistically analyzed using ANOVA. RESULTS: The composition of resin and type of fillers had a statistically significant effect on TP values (p < .05). The highest TP values were achieved around 50%-50% fractions of Bis-GMA and TEGDMA for series A and around 60%-40% fraction of Bis-GMA and TEGDMA for series B. Data showed that a high or low fraction of BisGMA resulted in a low translucent composite. Experimental resin composite (80% Bis-GMA) from series A was behaving similarly to Omnichroma in reference to TP values and color matching. CONCLUSIONS: Including fillers with RI of 1.53 into BisGMA/TEGDMA resin with RI of 1.524 resulted in composite resin providing a good color match with surrounding structure 'chameleon effect'.

"Fast" Plasmons Propagating in Graphene Plasmonic Waveguides with Negative Index Metamaterial Claddings.

We propose the monolayer graphene plasmonic waveguide (MGPW), which is composed of graphene core sandwiched by two graphene metamaterial (GMM) claddings and investigate the properties of plasmonic modes propagating in the waveguide. The effective refraction index of the GMMs claddings takes negative (or positive) at the vicinity of the Dirac-like point in the band structure. We show that when the effective refraction index of the GMMs is positive, the plasmons travel forward in the MGPW with a positive group velocity (vg > 0, vp > 0). In contrast-for the negative refraction index GMM claddings-a negative group velocity of the fundamental mode (vg < 0, vp > 0) appears in the proposed waveguide structure when the core is sufficiently narrow. A forbidden band appears between the negative and positive group velocity regions, which is enhanced gradually as the width of the core increases. On the other hand, one can overcome this limitation and even make the forbidden band disappear by increasing the chemical potential difference between the nanodisks and the ambient graphene of the GMM claddings. The proposed structure offers a novel scheme of on-chip electromagnetic field and may find significant applications in the future high density plasmonic integrated circuit technique.

Pectin characterisation using size exclusion chromatography: A comparison of ELS and RI detection.

A high-performance size-exclusion chromatography (HPSEC) method coupled to Evaporative Light Scattering (ELS) and Refractive Index (RI) detectors were evaluated and compared for the molecular mass (Mw) estimation of pectin in a wide range (0.342-805 kDa). Instrumental parameters of the ELSD were optimised by Response Surface Methodology (RSM) being 73 °C the evaporator temperature and 0.9 mL/min the air flow rate. The linear range for the ELSD concentration response was wider (10-2250 mg/L) and better (R2 = 0.985) than RID (10-1500 mg/L; R2 = 0.875). The limits of detection (LOD) and quantitation (LOQ) for all pullulans hardly changed in ELSD (LOD: 1.22-1.99 mg/L; LOQ: 4.07-6.63 mg/L); however, RID showed huge variations (LOD: 0.49-10.41 mg/L; LOQ: 1.64-34.70 mg/L), which increased with the Mw. In general, responses of both detectors were similar for the Mw estimation, although pectin characterisation with HPSEC-ELSD exhibited better results in the lowest Mw compounds.

Parallel Detection of Refractive Index Changes in a Porous Silicon Microarray Based on Digital Images.

A new technique for the refractive index change with high-sensitivity measurements was proposed by the digital image of porous silicon (PSi) microarray utilization in this paper. Under the irradiation of a He-Ne laser, the surface images of the PSi array cells with the microcavity structure were obtained by the digital imaging equipment, whereas the refractive index change of each array cells was detected by calculating the average gray value of the image and the refractive index change measurement sensitivity was 10-4. This technique could be utilized in the label-free and parallel detection of refraction index changes induced by a biological reaction in the microarray or the chip.

Control de calidad de la tintura al 20 % de hojas de Faramea occidentalis (L.) A. Rich. (Nabaco) / Quality control of tincture to 20 % obtained from the leaves of Faramea occidentalis (L.) A. Rich. (Nabaco)

INTRODUCCIÓN: Faramea occidentalis (L.) A. Rich. (Nabaco) se utiliza de forma tradicional como antiséptica, astringente, antidiarreica, antianémico y galactógeno. Por ello, se emplea en infusión y en baños para tratar la diarrea de los niños y los casos de anemia con diarrea. Hasta el momento en las fuentes consultadas no se han encontrado reportes sobre el control a los requisitos de la calidad de formulaciones farmacéuticas obtenidas a partir de esta planta. OBJETIVO: determinar algunos de los requisitos de calidad de la tintura al 20 % obtenida de las hojas de F. occidentalis. MÉTODOS: la planta fue colectada en la localidad de Cienaguilla, municipio Campechuela, provincia Granma, Cuba. El método de extracción aplicado fue la asistida por ultrasonido, utilizándose como menstruo una solución hidroetanólica. La determinación de los requisitos de calidad de la tintura se realizó analizándose cinco parámetros: requisitos organolépticos, pH, índice de refracción, sólidos totales y densidad relativa. Además, se emplearon métodos de análisis cromatográfico y espectroscópico para determinar la persistencia de los compuestos presentes en la tintura en un período de seis meses. RESULTADOS: los resultados obtenidos en el control de la calidad de la tintura al 20 % se encontraron dentro de los rangos de calidad establecidos por las normas utilizadas; y no presentaron diferencias significativas con los requisitos determinados en otras especies de la misma familia. CONCLUSIONES: el control de los requisitos de calidad mostró que la tintura al 20 % de las hojas de F. occidentalis, no manifestó cambios significativos en un período de seis meses que puedan comprometer su estabilidad como formulación farmacéutica. Esto indica que presenta un determinado grado de estabilidad, lo que constituye una garantía de la calidad y seguridad del producto.

INTRODUCTION: Faramea occidentalis (L.) A. Rich. (Rubiaceae) is traditionally used as antiseptic, astringent, antidiarrheal, antianemic and galactogenous. For that reason, it is used on infusion and baths to treat the diarrhea of the children and cases of anemia with diarrhea. Heretofore in the consulted sources reports about the control of quality requirements for pharmaceutical formulations obtained starting from this plant have not been found. OBJECTIVE: To determine some quality requirements of the tincture at 20 % obtained from the leaves of F. occidentalis. METHODS: The plant was collected in the Cienaguilla locality, Campechuela municipality, Granma province, Cuba. The applied extraction method was the extraction assisted by ultrasound, using as menses a hydroethanolic solution. The determination of quality requirements of the tincture was carried out analyzing five parameters: organoleptic requirements, pH, refraction index, total solids and relative density. In addition, chromatographic and spectroscopic methods were used to determine the persistence of the present compounds in the tincture in a period of six months. RESULTS: The results obtained in the quality control of the tincture at 20 % were found on quality ranges established by the used regulations; and they don't show significant differences according to the requirements determined in other species of the same family. CONCLUSIONS: The control of quality requirements showed that the tincture at 20 % of leaves of F. occidentalis did not manifest significant changes in a period of six months that can compromise his stability like pharmaceutical formulation. This indicates that it presents a certain grade of stability, what constitutes a guarantee of the quality and security of the product.

Comparison of the stratum corneum thickness measured in vivo with confocal Raman spectroscopy and confocal reflectance microscopy.

BACKGROUND: Thickness measurement of the outermost layer of the skin, the stratum corneum (SC), is essential for in-vivo measurement of the cutaneous bioavailability of topically applied drugs and cosmetics. Our aim was to compare SC thickness calculated from confocal Raman spectroscopy (CRS) data with results of SC thickness based on confocal laser scanning microscopy (CLSM) measurements and with literature data, to validate CRS data with CLSM data and vice versa. METHODS: SC thickness was measured with two non-invasive devices, confocal Raman spectroscopy and confocal laser scanning microscopy, on four different areas of the body: volar forearm, leg, face and palm in 18 healthy adult subjects. RESULTS: Comparable results of SC thickness were obtained with both methods, structure analysis of CLSM images, and computation of Fick's first law on water gradients measured with CRS: 20 µm and 19 µm (volar forearm), 21 µm and 22 µm (lower leg), and 13 µm with both methods (cheek), respectively. DISCUSSION: For the first time it was possible to accurately determine the thickness of SC with CRS and CLSM and to validate both systems against each other and with results of literature data. CONCLUSION: Both methods, CRS and CLSM, were found to be suitable to measure SC thickness correctly. Therefore, when using CRS, for example to obtain detailed information about the molecular composition of the skin, it is additionally possible to accurately measure SC thickness with the same device to have an orientation in which skin layer molecules are found.

Physical chemical and citotoxic evaluation of highly diluted solutions of Euphorbia tirucalli L. prepared through the fifty milesimal homeopathic method / Avaliação físico-química e citotóxica de soluções altamente diluídas de euphorbia tirucalli l. Preparada pelo método cinqüenta milesimal (lm) / Evaluación físico-química y citotóxica de soluciones altamente diluídas de Euphorbia tirucalli L. preparadas por el método homeopático cincuenta milesimal (LM)

Motivação: Embora Hahnemann tenha descrito o método LM na 6ª. Edição do Organon da Arte de Curar, poucas pesquisas tem sido feitas sobre as propriedades físico-químicas destas preparações. Além disso, ainda não existem evidências que apontem para a correlação entre propriedades físico-químicas e os efeitos biológicos das altas diluições. Objetivos: determinar características físico-químicas das preparações LM tais como condutividade elétrica, pH e índice de refração, bem como o efeito biológico em modelos experimentais. Materiais e Métodos: foi analisada uma série de diluições desde 1 lm até 10 lm de Euphorbia tirucalli L., preparada a partir do látex e do suco da planta. Para considerar as características sazonais desta planta, usamos 2 populações diferentes, colhidas uma em Junho de 2007 e outra em Maio de 2008. Além disso, o efeito citotóxico da Euphorbia tirucalli L. 5 lm foi testado em células humanas cancerosas (MCF7) através de ensaio MTT. Conclusões: Algumas diferenças entre as duas populações foram observadas. No entanto, nenhuma correlação clara pode ser observada entre as propriedades físico-químicas e a atividade biológica.

Background: although Hahnemann described the fifty-milesimal (LM) method in the 6th edition of the Organon of the Medical Art, very little research has been carried out on the physical chemical properties of these homeopathic preparations. Furthermore, there is still no evidence allowing for the correlation between the alleged physical chemical properties and the biological effects of high dilutions. Aims: to evaluate physical chemical characteristics of LM preparations including electrical conductivity, pH and refraction index, and their effect on biological experimental models. Materials and methods: preparations tested for physical chemical analysis were dilutions 1 lm to 10 lm of Euphorbia tirucalli L. prepared from the latex and the juice of the plant. To rule the seasonal characteristics of this plant, 2 different populations were used, one collected in June 2007 and the other in May 2008. Furthermore, the cytotoxic effect of Euphorbia tirucalli 5 lm was tested on human breast cancer cells (MCF7) through MTT assay. Conclusions: Some differences among the two collections were observed. However, any clear correlation could be observed between physical chemical properties and biological activity.

Motivación: Aunque Hahnemann describió el métodocincuenta milesimal (LM) en la 6 ª edición del Organon del Arte Médica, muy poca investigación se ha realizado sobre las propiedades físico-químicas de estos preparados homeopáticos. Por otra parte, todavía no hay pruebas que permitan la correlación entre las presuntas propiedades físico-químicas y los efectos biológicos, de las altas diluciones. Objetivos: evaluar las características físico-químicas de los preparados LM, incluyendo conductividad eléctrica, pH y el índice de refracción, y su efecto en modelos biológicos experimentales. Materiales y métodos: las muestras para el análisis físico-químico fueron diluciones 1 a 10 lm de Euphorbia tirucalli L. preparadas a partir del látex y el jugo de la planta. Para descartar las características sazonales de esta planta, dos poblaciones diferentes fueron utilizadas, una recogida en junio de 2007 y otro en mayo de 2008. Además, el efecto citotóxico de Euphorbia tirucalli 5 lm fue probado en células humanas de cáncer de mama (MCF7) a través del ensayo MTT. Conclusiones: Algunas diferencias entre las dos colecciones se observaron. Sin embargo, ninguna correlación clara se observó entre las propiedades físicas- químicas y actividad biológica.

Dispersión y número ABBE / Dispersion and ABBE number

Las alternativas que existen en cuanto a materiales y diseños de lentes oftálmicos, hacen que el decidir el lente ideal para una determinada prescripción, sea una tarea difícil, si no se conoce a fondo las propiedades ópticas y físicas de los mismos.En el presente trabajo se describe como el índice de refracción de un material depende de la longitud de onda de la luz a través de la polarización eléctrica, dando lugar al proceso de dispersión. En lentes oftálmicos, la dispersión cromática está caracterizada por el número ABBE. Se muestran algunas definiciones para este valor, su importancia y como minimizar sus efectos en los lentes oftálmicos.

The current alternatives regarding materials and designs of ophthalmic lenses makes difficult to decidethe ideal lens for a specific prescription, ofcourse if optical and physical properties are notknown in depth. This article describes how therefraction index of a material depends on the lightwave longitude through electrical polarization,producing the dispersion process. In ophthalmiclenses, chromatic dispersion is characterized by theAbbe number. Some definitions for this number, itsimportance and how to minimize its effects inophthalmic lenses are also shown.