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1.
Nat Commun ; 12(1): 3246, 2021 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-34059690

RESUMO

Biosensors are indispensable tools for public, global, and personalized healthcare as they provide tests that can be used from early disease detection and treatment monitoring to preventing pandemics. We introduce single-wavelength imaging biosensors capable of reconstructing spectral shift information induced by biomarkers dynamically using an advanced data processing technique based on an optimal linear estimator. Our method achieves superior sensitivity without wavelength scanning or spectroscopy instruments. We engineered diatomic dielectric metasurfaces supporting bound states in the continuum that allows high-quality resonances with accessible near-fields by in-plane symmetry breaking. The large-area metasurface chips are configured as microarrays and integrated with microfluidics on an imaging platform for real-time detection of breast cancer extracellular vesicles encompassing exosomes. The optofluidic system has high sensing performance with nearly 70 1/RIU figure-of-merit enabling detection of on average 0.41 nanoparticle/µm2 and real-time measurements of extracellular vesicles binding from down to 204 femtomolar solutions. Our biosensors provide the robustness of spectrometric approaches while substituting complex instrumentation with a single-wavelength light source and a complementary-metal-oxide-semiconductor camera, paving the way toward miniaturized devices for point-of-care diagnostics.


Assuntos
Técnicas Biossensoriais , Neoplasias da Mama/diagnóstico , Técnicas Analíticas Microfluídicas/instrumentação , Testes Imediatos , Refratometria/instrumentação , Neoplasias da Mama/sangue , Exossomos/química , Feminino , Humanos , Técnicas Analíticas Microfluídicas/métodos , Nanopartículas/química , Refratometria/métodos , Análise Espectral/instrumentação , Análise Espectral/métodos
2.
Sci Rep ; 10(1): 6705, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32317712

RESUMO

In the production of 2nd generation ethanol, using Saccharomyces cerevisiae, the highest productivity obtained using C5/C6 fermenting yeast is in the co-fermentation phase, in which xylose and glucose are fermented simultaneously. Extending this phase in a fed-batch process increases the yield, rate and additionally reduces needed yeast amount for pitching. Extending this phase, as long as possible, would further enhance yield and economy of the process. To realise the concept a fermentation monitoring technique was developed and applied. Based on online measured refractive index an optimal residual sugar concentration could be maintained in the primary fermentor during the feed phase, requiring little knowledge of the nature of the substrate. The system was able to run stably for at least five fermentor volumes giving an ethanol yield >90% throughout the run. This was achieved with addition of only urea to the wheat straw hydrolysate and with an initial yeast pitch of 0.2 g/L total of finished broth. It has the potential to improve the fermentation technology used in fuel ethanol plants, which could help to meet the growing demand for more sustainable fuels.


Assuntos
Técnicas de Cultura Celular por Lotes , Carbono/metabolismo , Fermentação , Refratometria/instrumentação , Saccharomyces cerevisiae/metabolismo , Triticum/química , Reatores Biológicos/microbiologia , Hidrólise , Sistemas On-Line , Fatores de Tempo
3.
Talanta ; 213: 120815, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32200920

RESUMO

Lead ions are deleterious pollutants that often reach drinking water, and can cause significant harm to humans (particularly children). An ultra-sensitive lead ion detection method using a whispering gallery mode (WGM) optofluidic microbubble resonator and the classic GR-5 DNAzyme is proposed in this paper. With the auxiliary piranha and Ploy-l-lysine solution, GR-5 DNAzyme was successfully modified on the inner wall of a microbubble. The mode field distribution of the microbubble was analysed, and the optofluidic sensor with thin wall exhibited a maximum bulk refractive index sensitivity of 265.2 nm/RIU. Lead ions at concentrations ranging from 0.1 pM to 100 pM were tested using the proposed WGM optofluidic sensor. The noise was decreased to 2.43 fM using the self-referenced differential method. Thus, a limit of approximately 15 fM was obtained for the detection of lead ions using the WGM optofluidic biosensor. Eight competing metal ions were also used to evaluate the selectivity of the proposed sensor, with results indicating that it has high selectivity for lead ions. Finally, the sensor performance is verified using real samples.


Assuntos
Técnicas Biossensoriais/instrumentação , DNA Catalítico/química , Chumbo/análise , Poluição Química da Água/análise , Desenho de Equipamento , Íons/análise , Limite de Detecção , Refratometria/instrumentação , Rios/química
4.
J Vet Diagn Invest ; 32(1): 36-43, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31876254

RESUMO

Urine specific gravity (USG), which is usually measured by refractometry, is an important indicator of renal concentrating ability. Few studies have evaluated refractometers with separate scales for canine and feline urine. Variables such as protein content or storage time may influence the USG. We compared the effects of measuring USG with a refractometer with single or separate scales for canine and feline urine, investigated inter- and intra-observer variability, and measured agreement between whole urine and supernatant. We evaluated the correlation between USG and osmolality, the influence of urinary protein on USG and osmolality, and the impact of storage time up to 6 mo. We examined 252 canine and 126 feline samples. Bland-Altman analysis revealed higher USG values of the single-scale refractometer than the dual-scale refractometer, with a mean difference (bias) of < 0.001 for canine and 0.003 for feline specimens. Inter- and intra-observer variability were acceptable. Good agreement was shown between USG of whole urine and supernatant. Correlations between USG and osmolality were excellent (0.98-0.99, p < 0.001). Proteinuria up to 1 g/L had no major impact on USG or osmolality. Storage time had no significant effect on USG. The difference between the refractometers is clinically irrelevant, and the use of a refractometer with separate feline and canine scales is unnecessary. Whole urine and supernatant stored up to 6 mo can both be used for USG measurement. The influence of proteinuria <1 g/L on USG and osmolality is negligible.


Assuntos
Gatos/urina , Cães/urina , Refratometria/veterinária , Urinálise/veterinária , Animais , Concentração Osmolar , Refratometria/instrumentação , Gravidade Específica , Urinálise/instrumentação
5.
Biosens Bioelectron ; 150: 111905, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31791874

RESUMO

The use of plasmonic metasurface for sensing has great potential on label-free detection of human tumor markers, which could benefit clinical examination. In this work, we adopt nanoimprint and plasma etching to optimize the nanofabrication for low-cost flexible plasmonic metasurface sensors with gold nanobump arrays, which enable facile surface bio-functionality, high sensitivity and simple optical measurement in the visible range. A high bulk refractive index sensitivity of 454.4 nm/RIU is achieved for the prototype plasmonic metasurface sensors at the wavelengths from 620 nm to 720 nm. The rapid quantitative tumor marker sensing of carcinoembryonic antigen in human serum samples from less than 10 ng/mL to more than 87 ng/mL is achieved, which demonstrates good agreement with the conventional chemiluminescence immunoassay system and sufficiently covers the threshold tumor marker concentration of 20 ng/mL for early cancer prediction. Our method is capable of low-cost high-throughput manufacturing for flexible lightweight plasmonic metasurface sensors, which will facilitate wide applications on portable biomedical sensing devices for future point-of-care diagnosis and mobile healthcare.


Assuntos
Anticorpos Imobilizados/química , Técnicas Biossensoriais/instrumentação , Antígeno Carcinoembrionário/sangue , Ouro/química , Nanoestruturas/química , Biomarcadores Tumorais/sangue , Desenho de Equipamento , Humanos , Nanoestruturas/ultraestrutura , Neoplasias/sangue , Refratometria/instrumentação
6.
ACS Sens ; 4(12): 3133-3140, 2019 12 27.
Artigo em Inglês | MEDLINE | ID: mdl-31793768

RESUMO

Remote detection of hydrogen, without the utilization of electronic component or elevated temperature, is one of the hot topics in the hydrogen technology and safety. In this work, the design and realization of the optical fiber-based hydrogen sensor with unique characteristics are proposed. The proposed sensor is based on the gold-coated multimode fiber, providing the plasmon properties, decorated by the IRMOF-20 layer with high selectivity and affinity toward hydrogen. The IRMOF-20 layer was grown by a surface-assisted technique, and its formation and properties were studied using X-ray photoelectron spectroscopy, Raman, X-ray diffraction, and Brunauer-Emmett-Teller techniques. Simultaneous ellipsometry results indicate the apparent changes of the refractive index of the IRMOF-20 layer due to hydrogen sorption. As results, the presence of hydrogen led to the pronounced changes of plasmon band wavelength position as well as its intensity increase. The proposed hydrogen sensors were favorably distinguished by a high response/recovery rate, excellent selectivity toward the hydrogen, very low temperature dependency, functionality at room or lower temperature, insensitivity toward the humidity, and the presence of CO2, CO, or NO2. Additionally, the proposed hydrogen sensor showed good reversibility, reproducibility, and long-term stability.


Assuntos
Ouro/química , Hidrogênio/análise , Estruturas Metalorgânicas/química , Fibras Ópticas , Refratometria/métodos , Refratometria/instrumentação , Reprodutibilidade dos Testes
7.
Acta Vet Scand ; 61(1): 59, 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31805965

RESUMO

BACKGROUND: There is an increased interest in using digital refractometers to indirectly assess colostrum quality of dairy cattle, but knowledge on diagnostic accuracy for Norwegian Red dairy cows is lacking. Recent research has indicated a profound variability in the colostrum quality among dairy cows and herds in Norway. The aim of this study was to evaluate the diagnostic test sensitivity and specificity of a digital refractometer (Brix refractometer) at different cut-offs in Brix% for detection of colostrum of high quality (> 50 g/L) defined by the gold standard single radial immunodiffusion (IgG g/L). Furthermore, we aimed to identify possible associations between selected herd and cow-level management factors and colostrum IgG-levels in Norwegian Red dairy cows. RESULTS: Median colostrum IgG level across 167 cows from 19 herds was 35.0 g/L, ranging from 5 to 129 g/L. Mean Brix% (± SD) was 19.7 ± 4.12%, ranging from 10.1 to 30.5. Most samples (72.5%) had inferior quality as compared to the international standard of 50 g/L. Brix% and IgG in colostrum were strongly correlated (r = 0.71, P < 0.001). A Brix cut-off of 22%, which is currently recommended, yielded a sensitivity of (95% CI) 69.4% (54.6-81.7) and a specificity of 83.1% (75.0-89.3) for identifying colostrum with high quality (> 50 g/L). The only factor found to be associated with low colostrum quality was parity. Specifically, cows in the second parity were found to produce colostrum with low quality compared to cows in parities four and later. CONCLUSIONS: The agreement between colostrum IgG and Brix% is good. However, the diagnostic test evaluation indicates suboptimal performance in identifying high vs. low colostrum quality in this population, possibly related to a high proportion of the samples with < 50 g/L IgG. The only factor found to be associated with low colostrum quality was parity. Specifically, cows in the second parity were found to produce colostrum with lower quality. Future research should investigate colostrum and serum IgG levels which best prevent calf illness under Norwegian conditions.


Assuntos
Colostro/fisiologia , Indústria de Laticínios , Testes Diagnósticos de Rotina/veterinária , Imunoglobulina G/análise , Refratometria/veterinária , Animais , Bovinos , Indústria de Laticínios/métodos , Testes Diagnósticos de Rotina/métodos , Feminino , Refratometria/instrumentação , Sensibilidade e Especificidade
8.
ACS Sens ; 4(12): 3325-3332, 2019 12 27.
Artigo em Inglês | MEDLINE | ID: mdl-31782299

RESUMO

The study of biophysical properties of single cells is becoming increasingly relevant in cell biology and pathology. The measurement and tracking of magnitudes such as cell stiffness, morphology, and mass or refractive index have brought otherwise inaccessible knowledge about cell physiology, as well as innovative methods for high-throughput label-free cell classification. In this work, we present hollow resonator devices based on suspended glass microcapillaries for the simultaneous measurement of single-cell buoyant mass and reflectivity with a throughput of 300 cells/minute. In the experimental methodology presented here, both magnitudes are extracted from the devices' response to a single probe, a focused laser beam that enables simultaneous readout of changes in resonance frequency and reflected optical power of the devices as cells flow within them. Through its application to MCF-7 human breast adenocarcinoma cells and MCF-10A nontumorigenic cells, we demonstrate that this mechano-optical technique can successfully discriminate pathological from healthy cells of the same tissue type.


Assuntos
Refratometria/métodos , Dióxido de Silício/química , Análise de Célula Única/métodos , Humanos , Células MCF-7 , Tamanho da Partícula , Estudo de Prova de Conceito , Refratometria/instrumentação , Análise de Célula Única/instrumentação
9.
Vet Clin Pathol ; 48(4): 702-709, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31612506

RESUMO

BACKGROUND: Refractometry is often used in clinical veterinary medicine to estimate urine concentration. Variability among commonly-used refractometers has not been critically evaluated. OBJECTIVE: This study aimed to evaluate the variability of urine specific gravity (USG) among four refractometers and compare results of USG measurements with those of urine osmolality (Uosm ), the gold standard for determining urine concentrations. METHODS: USG was determined in 100 dogs using three optical refractometers, the American Optical Abbe refractometer 10450, Reichert TS 400 refractometer, and Heska Veterinary refractometer 2737-E02, and one digital refractometer, the Misco Palm Abbe Digital refractometer #PA203. Results were compared between each pair of refractometers and between each refractometer and urine osmolality determined by freezing point depression using a Multi-Osmette 2430E osmometer. Results were analyzed with Bland-Altman plots and Passing-Bablok regression analysis. RESULTS: The Reichert, Heska, and Misco refractometers provide USG measurements that can be used interchangeably based on small differences, consistently less than 0.002, between the USG measurements. The AO refractometer measured USG values with much larger differences, which were deemed clinically significant by the study parameters. None of the refractometers were able to accurately predict Uosm or vice versa within a clinically acceptable range. CONCLUSIONS: Varying degrees of differences were seen in the USG measurements among the different refractometers. These differences were refractometer-dependent, and the results from one instrument could affect clinical decisions.


Assuntos
Cães/urina , Refratometria/veterinária , Urinálise/veterinária , Animais , Feminino , Masculino , Concentração Osmolar , Refratometria/instrumentação , Gravidade Específica , Urinálise/instrumentação , Urina
10.
J Synchrotron Radiat ; 26(Pt 5): 1514-1522, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31490139

RESUMO

Free-electron lasers (FELs) based on superconducting accelerator technology and storage ring facilities operate with bunch repetition rates in the MHz range, and the need arises for bunch-by-bunch electron and photon diagnostics. For photon-pulse-resolved measurements of spectral distributions, fast one-dimensional profile monitors are required. The linear array detector KALYPSO (KArlsruhe Linear arraY detector for MHz-rePetition rate SpectrOscopy) has been developed for electron bunch or photon pulse synchronous read-out with frame rates of up to 2.7 MHz. At the FLASH facility at DESY, a current version of KALYPSO with 256 pixels has been installed at a grating spectrometer as online diagnostics to monitor the pulse-resolved spectra of the high-repetition-rate FEL pulses. Application-specific front-end electronics based on MicroTCA standard have been developed for data acquisition and processing. Continuous data read-out with low latency in the microsecond range enables the integration into fast feedback applications. In this paper, pulse-resolved FEL spectra recorded at 1.0 MHz repetition rate for various operation conditions at FLASH are presented, and the first application of an adaptive feedback for accelerator control based on photon beam diagnostics is demonstrated.


Assuntos
Refratometria/instrumentação , Elétrons , Desenho de Equipamento , Lasers , Fótons , Espalhamento de Radiação , Síncrotrons
11.
J Synchrotron Radiat ; 26(Pt 5): 1572-1581, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31490146

RESUMO

An X-ray amplitude-splitting interferometer based on compound refractive lenses, which operates in the reflection mode, is proposed and realized. The idea of a reflecto-interferometer is to use a very simplified experimental setup where a focused X-ray beam reflected from parallel flat surfaces creates an interference pattern in a wide angular range. The functional capabilities of the interferometer were experimentally tested at the European Synchrotron Radiation Facility (ESRF) ID06 beamline in the X-ray energy range from 10 keV to 15 keV. The main features of the proposed approach, high spatial and temporal resolution, were demonstrated experimentally. The reflections from free-standing Si3N4 membranes, gold and resist layers were studied. Experimentally recorded interferograms are in good agreement with our simulations. The main advantages and future possible applications of the reflecto-interferometer are discussed.


Assuntos
Interferometria/instrumentação , Lentes , Refratometria/instrumentação , Desenho de Equipamento , Síncrotrons , Raios X
12.
Biosens Bioelectron ; 144: 111693, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31539719

RESUMO

Biosensor technology is an active field of research and development presenting rapid progress in recent decades, and the subfield of optical biosensors based on refractometric sensing schemes has developed dramatically during this time. This review focuses on advances in the refractometric sensing-based guided-wave optical biosensors particularly in the last two decades. It starts with a concise discussion on the underlying principles of label-free refractometric biosensor. Subsequently, advances in biosensor design, especially the transducer configuration and the integration of the sensing device are reviewed, highlighting the challenges and efforts dedicated to improving this technology. Various surface functionalization strategies designed to produce well-defined and reproducible surface properties are introduced for evaluation. Refractometric sensing scheme-based optical biosensors have found versatile applications varying from environmental monitoring and food safety to clinical diagnostics, together with advances in these applications and others are described. This paper concludes with a brief discussion on the outlook for integrating biosensors with emerging technologies.


Assuntos
Técnicas Biossensoriais/métodos , Óptica e Fotônica/métodos , Refratometria/métodos , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/tendências , Humanos , Óptica e Fotônica/instrumentação , Óptica e Fotônica/tendências , Patologia Molecular/tendências , Refratometria/instrumentação , Refratometria/tendências
13.
Biosens Bioelectron ; 141: 111396, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31195197

RESUMO

Mode volume overlap factor is one of the parameters determining the sensitivity of a sensor. In past decades, many approaches have been proposed to increase the mode volume overlap. As the increased mode volume overlap factor results in reduced mode confinement, the maximum value is ultimately determined by the micro- and nano-structure of the refractive index distribution of the sensing devices. Due to the asymmetric index profile along the vertical direction on silicon-on-insulator platform, further increasing the sensitivity of subwavelength grating metamaterial (SGM) waveguide based sensors is challenging. In this paper, we propose and demonstrate pedestaled SGM which reduces the asymmetricity and thus allows further increasing the interaction between optical field and analytes. The pedestal structure can be readily formed by a controlled undercut etching. Both theoretical analysis and experimental demonstration show a significant improvement of sensitivity. The bulk sensitivity and surface sensitivity are improved by 28.8% and 1000 times, respectively. The detection of streptavidin at a low concentration of 0.1 ng/mL (∼1.67 pM) is also demonstrated through real-time monitoring of the resonance shift. A ∼400 fM streptavidin limit of detection is expected with a 0.01nm resolution spectrum analyzer based on the real-time measurement of streptavidin detection results from two-site binding model fitting.


Assuntos
Técnicas Biossensoriais/instrumentação , Refratometria/instrumentação , Algoritmos , Desenho de Equipamento , Silício/química , Estreptavidina/análise
14.
J Dairy Sci ; 102(8): 7459-7463, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31202644

RESUMO

Transition milk is a source of immunoglobulin G (IgG) and could potentially be used to provide calves with passive immunity, when the IgG concentration is ≥50 g/L. Assessment of IgG concentrations in transition milk would be required before feeding and could be conducted using cow-side tests such as refractometers. Currently, limited information is available on the ability of refractometers to assess transition milk quality. We hypothesized that digital refractometry could be used to provide an accurate cow-side assessment of IgG concentrations in colostrum and transition milk, and IgG concentration in colostrum and one or more transition milking in an Irish herd is >50 g/L. The objectives of this study were to determine the IgG concentrations in colostrum and first, second, third, fourth, and fifth transition milk, and determine the utility of a digital refractometer in assessing quality of colostrum and transition milk produced by cows in a pasture-based dairy production system. A convenient sample of 75 dairy cows were enrolled. Colostrum and transition milk IgG concentrations were determined by radial immunodiffusion and refractometry. Sensitivity and specificity of the refractometer were determined and cut-off points that maximized sensitivity and specificity were determined using receiver operating characteristic curves. Median (range) IgG concentrations in colostrum and first, second, third, fourth, and fifth milking were 99.6, 43.5, 12.5, 5.3, 1.9, and 1.8 g/L, respectively. The sensitivity (0.8-1) of digital refractometry in identifying samples with low IgG concentrations in colostrum, first, second, and third transition milk was acceptable. In contrast, digital refractometry was not useful for assessing IgG concentrations in the fourth and fifth milking due to low IgG concentrations.


Assuntos
Colostro/imunologia , Imunoglobulina G/análise , Refratometria/veterinária , Animais , Bovinos , Feminino , Imunodifusão/veterinária , Leite , Gravidez , Curva ROC , Refratometria/instrumentação , Sensibilidade e Especificidade
15.
J. optom. (Internet) ; 12(2): 99-110, abr.-jun. 2019. tab, graf
Artigo em Inglês | IBECS | ID: ibc-180890

RESUMO

Purpose: To determine the agreement and validity of keratometric measurements in children with the Nidek ARK-510A auto-refractokeratometer compared to rotating Scheimpflug imaging with Pentacam and biograph with Lenstar LS 900. Methods: This study was conducted on 5620 schoolchildren aged 6-12 years in Shahroud, Iran. Minimum and maximum keratometry values and corneal astigmatism magnitude were compared by calculation of Paired difference, interclass correlation coefficient, and 95% limits of agreement (LoA) between devices. Results: After applying the exclusion criteria, 4215 right eyes were enrolled into the study. Mean minimum keratometry with Nidek ARK-510A, Pentacam, and Lenstar was 43.13 ± 1.51, 43.14 ± 1.48, and 42.87 ± 1.46 diopters (D), respectively, and mean maximum keratometry was 43.97 ± 1.59, 44.00 ± 1.56, and 43.75 ± 1.54D, respectively. Nidek ARK-510A overestimated minimum and maximum keratometry by 0.25 ± 0.37 and 0.22 ± 0.41, respectively, compared to Penatcam. The LoA between Nidek ARK-510A and Pentacam for minimum and maximum keratometry measurements were -0.98 to 0.47D and −1.02 to 0.57D, respectively. The LoA between Nidek ARK-510A and Lenstar for minimum and maximum keratometry measurements were -0.70 to 0.72D and -0.79 to 0.85D, respectively. The agreement between devices was best in emmetropes, worst in hyperopes. For astigmatic vector components, the agreements between devices were poor but best agreement was between Nidek ARK-510A and Pentacam. Conclusions: Keratometry measurement with Nidek ARK-510A was not significantly different from Pentacam and Lenstar, and this device can be used in screening programs in emmetropes


Objetivo: Determinar la concordancia y validez de las mediciones queratométricas en niños con el autorefractoqueratómetro Nidek ARK-510A, comparadas con las imágenes de Scheimpflug con Pentacam y el biómetro Lenstar LS 900. Métodos: Este estudio se realizó en 5.620 niños, de edades comprendidas entre 6 y 12 años, en Shahroud, Irán. Se compararon los valores queratométricos mínimo y máximo y la magnitud del astigmatismo corneal mediante cálculo de diferencia pareada, coeficiente de correlación inter-clase, y límites de comcordancia del 95% (LoA) entre dispositivos. Resultados: Tras aplicar los criterios de exclusión, se incluyeron 4.215 ojos derechos en el estudio. Los valores de queratometría mínima media con Nidek ARK-510A, Pentacam y Lenstar fueron de 43,13 ± 1,51, 43,14 ± 1,48, y 42,87 ± 1,46 dioptrías (D), respectivamente, siendo los valores de queratometría máxima media de 43,97 ± 1,59, 44 ± 1,56, y 43,75 ± 1,54 D, respectivamente. Nidek ARK-510A sobre-estimó la queratometría mínima y máxima en 0,25 ± 0,37 y 0,22 ± 0,41, respectivamente, en comparación con Penatcam. El LoA entre Nidek ARK-510A y Pentacam para las mediciones de queratometría mínima y máxima fue de -0,98 a 0,47 D y -1,02 a 0,57 D, respectivamente. El LoA entre Nidek ARK-510A y Lenstar para las mediciones de queratometría mínima y máxima fue de -0,7 a 0,72 D y -0,79 a 0,85 D, respectivamente. El acuerdo entre dispositivos fue mejor en emétropes, y peor en hipermétropes. Para los componentes del vector astigmático, los acuerdos entre dispositivos fueron débiles, aunque existió una mejor concordancia entre Nidek ARK-510A y Pentacam. Conclusiones: La medición de la queratometría realizada con Nidek ARK-510A no fue significativamente diferente a la realizada con Pentacam y Lenstar, pudiendo utilizarse este dispositivo en los programas de chequeo en emétropes


Assuntos
Humanos , Masculino , Feminino , Criança , Refratometria/métodos , Erros de Refração/diagnóstico , Astigmatismo/diagnóstico , Emetropia/fisiologia , Refratometria/instrumentação , Valores de Referência , Biometria/métodos , Estudos Transversais
16.
Appl Opt ; 58(12): 3187-3192, 2019 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-31044793

RESUMO

A bilayer asymmetric photonic crystal slab made of porous Si3N4/SiO2 is designed as a biosensor by considering the optical performance of this photonic crystal slab with a square lattice based on rigorous coupled-wave analysis theory and wavelength interrogation methods. The results show that this bilayer asymmetric photonic crystal can be used as a biosensor according to its excellent linearity relationship between the guided resonance peak shift and refractive index of aqueous solution with or without glycerol. The theoretical sensitivity value of the bilayer asymmetric photonic crystal biosensor is achieved as (S>286 nm/RIU) in the wavelength range from 1400 nm to 1600 nm. These results also indicate that the asymmetry bilayer structure has an important influence on its optical characteristic and sensitivity of the bilayer photonic crystal biosensor, and hence, it can be modified by changing the lattice constant and slab thickness. This research paper is very useful for understanding the application and design of biosensors based on porous structures.


Assuntos
Técnicas Biossensoriais/instrumentação , Compostos de Silício/química , Dióxido de Silício/química , Cristalização , Fótons , Refratometria/instrumentação , Espalhamento de Radiação
17.
Mil Med ; 184(11-12): e632-e636, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31004429

RESUMO

INTRODUCTION: Dehydration can have an immediate negative impact on the performance of Soldiers in training or combat environments. Field expedient methods for assessing hydration status may be valuable for service members. Measurement of urine-specific gravity (USG) via refractometer is inexpensive, simple, fast, and a validated indicator of hydration status. Manual (MAN) and digital (DIG) refractometers are commonly used in laboratory settings however, digital (DIG) devices have not been validated in the field against MAN devices. The purpose of this study was to determine the validity and feasibility of using a DIG refractometer to assess USG compared to a MAN refractometer during a military field training exercise. MATERIALS AND METHODS: Fifty-six military service members provided 672 urine samples during two 10-day field training exercises in central Texas. USG was assessed using a MAN and a DIG refractometer with cutoff value of ≥1.020 indicating hypohydration. The study received a non-human research determination. RESULTS: The MAN measurements were strongly correlated with the DIG (r = 0.91, p < 0.0001) measurements. Bland-Altman analysis demonstrated agreement between the refractometers. The DIG displayed good sensitivity (93.9%) and specificity (85.8%) compared to the MAN. CONCLUSION: The DIG refractometer used in this study was reliable and valid compared with a MAN device and was feasible for use in a field environment; however, the DIG refractometer tended to over overestimate hypohydration.


Assuntos
Refratometria/instrumentação , Refratometria/normas , Gravidade Específica , Ensino/tendências , Urina , Desenho de Equipamento/normas , Humanos , Refratometria/métodos , Texas , Urinálise/instrumentação , Urinálise/métodos , Urinálise/tendências
18.
Biosens Bioelectron ; 132: 368-374, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30901726

RESUMO

A simple, convenient, and inexpensive method to fabricate optical fiber based biosensors which utilize periodic hole arrays in gold films for signal transduction is reported. The process of hole array formation mainly relies on self-assembly of hydrogel microgels in combination with chemical gold film deposition and subsequent transfer of the perforated film onto an optical fiber tip. In the fabrication process solely chemical wet lab techniques are used, avoiding cost-intensive instrumentation or clean room facilities. The presented method for preparing fiber optic plasmonic sensors provides high throughput and is perfectly suited for commercialization using batch processing. The transfer of the perforated gold film onto an optical fiber tip does not affect the sensitivity of the biosensor ((420 ±â€¯83) nm/refractive index unit (RIU)), which is comparable to sensitivities of sensor platforms based on periodic hole arrays in gold films prepared by significantly more complex methods. Furthermore, real-time and in-line immunoassay studies with a specially designed 3D printed flow cell are presented exploiting the presented optical fiber based biosensors.


Assuntos
Tecnologia de Fibra Óptica/instrumentação , Imunoensaio/instrumentação , Imunoglobulina G/análise , Ressonância de Plasmônio de Superfície/instrumentação , Animais , Desenho de Equipamento , Cabras , Ouro/química , Fibras Ópticas , Impressão Tridimensional , Coelhos , Refratometria/instrumentação
19.
J Optom ; 12(2): 99-110, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30879970

RESUMO

PURPOSE: To determine the agreement and validity of keratometric measurements in children with the Nidek ARK-510A auto-refractokeratometer compared to rotating Scheimpflug imaging with Pentacam and biograph with Lenstar LS 900. METHODS: This study was conducted on 5620 schoolchildren aged 6-12 years in Shahroud, Iran. Minimum and maximum keratometry values and corneal astigmatism magnitude were compared by calculation of Paired difference, interclass correlation coefficient, and 95% limits of agreement (LoA) between devices. RESULTS: After applying the exclusion criteria, 4215 right eyes were enrolled into the study. Mean minimum keratometry with Nidek ARK-510A, Pentacam, and Lenstar was 43.13±1.51, 43.14±1.48, and 42.87±1.46 diopters (D), respectively, and mean maximum keratometry was 43.97±1.59, 44.00±1.56, and 43.75±1.54D, respectively. Nidek ARK-510A overestimated minimum and maximum keratometry by 0.25±0.37 and 0.22±0.41, respectively, compared to Penatcam. The LoA between Nidek ARK-510A and Pentacam for minimum and maximum keratometry measurements were -0.98 to 0.47D and -1.02 to 0.57D, respectively. The LoA between Nidek ARK-510A and Lenstar for minimum and maximum keratometry measurements were -0.70 to 0.72D and -0.79 to 0.85D, respectively. The agreement between devices was best in emmetropes, worst in hyperopes. For astigmatic vector components, the agreements between devices were poor but best agreement was between Nidek ARK-510A and Pentacam. CONCLUSIONS: Keratometry measurement with Nidek ARK-510A was not significantly different from Pentacam and Lenstar, and this device can be used in screening programs in emmetropes.


Assuntos
Astigmatismo/diagnóstico , Biometria/instrumentação , Córnea , Doenças da Córnea/diagnóstico , Topografia da Córnea/instrumentação , Técnicas de Diagnóstico Oftalmológico/instrumentação , Refratometria/instrumentação , Criança , Córnea/patologia , Córnea/fisiopatologia , Feminino , Humanos , Masculino , Imagem Óptica/instrumentação , Fotografação/instrumentação , Estudos Prospectivos , Reprodutibilidade dos Testes
20.
J Biomed Opt ; 24(3): 1-5, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30848110

RESUMO

The refractive index of blood is a key biophysical parameter, which can reflect the physiological state. We measured the refractive index of whole blood and other components, such as serum, plasma, and hemoglobin, based on internal reflection by using a homemade apparatus in the spectral range of 400 to 750 nm. In addition to the hemoglobin solution, which has a Soret band about 420 nm and two Q-bands between 500 and 600 nm, the measurements of other samples are the normal dispersion curve. The results are approximated by the Cauchy equation and Sellmeier equation, and the correlation coefficients are more than 0.997.


Assuntos
Análise Química do Sangue/métodos , Refratometria/métodos , Animais , Análise Química do Sangue/instrumentação , Desenho de Equipamento , Hemoglobinas/análise , Humanos , Masculino , Oxigênio/sangue , Coelhos , Refratometria/instrumentação
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