Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 15.120
Filtrar
1.
Nature ; 577(7788): 34-35, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31894155
2.
J Chem Phys ; 151(21): 211101, 2019 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-31822097

RESUMO

Cesium lead bromide (CsPbBr3) perovskite has attracted great attention recently for its potentials for next-generation green-color lasing devices owing to the relatively high structural stability and the high emission efficiency among the perovskite family. Herein, we explore the origins of cavity modes in CsPbBr3 microplatelets (MPs) lasers by using angle-resolved microphotoluminescence Fourier imaging technique, which is still controversial so far. In-plane Fabry-Pérot (F-P) mode lasing transition to whispering-gallery-mode (WGM) lasing is verified at room temperature, which mostly occurs in large MPs with edge length (L) over 13 µm. The F-P lasing is suppressed upon decreasing L or increasing excitation density, and the WGM lasing is predominant for all MPs at high excitation density. Furthermore, the parity and symmetry of in-plane F-P modes are classified. These results advance the fundamental understanding of lasing modes in planar microcavities as well as their applications in on-chip interconnection and quantum optics.


Assuntos
Compostos de Cálcio/química , Lasers , Óxidos/química , Titânio/química , Óptica e Fotônica , Tamanho da Partícula , Teoria Quântica , Propriedades de Superfície
3.
Ophthalmic Physiol Opt ; 39(6): 459-468, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31696535

RESUMO

PURPOSE: Optical filters and tints manipulating short-wavelength light (sometimes called 'blue-blocking' or 'blue-attenuating' filters) are used in the management of a range of ocular, retinal, neurological and psychiatric disorders. In many cases, the only available quantification of the optical effects of a given optical filter is the spectral transmittance, which specifies the amount of light transmitted as a function of wavelength. METHODS: We propose a novel physiologically relevant and retinally referenced framework for quantifying the visual and non-visual effects of these filters, incorporating the attenuation of luminance (luminous transmittance), the attenuation of melanopsin activation (melanopsin transmittance), the colour shift, and the reduction of the colour gamut (gamut reduction). Using these criteria, we examined a novel database of spectral transmittance functions of optical filters (n = 121) which were digitally extracted from a variety of sources. RESULTS: We find a large diversity in the alteration of visual and non-visual properties. The spectral transmittance properties of the examined filters vary widely, in terms of shapes and cut-off wavelengths. All filters show relatively more melanopsin attenuation than luminance attenuation (lower melanopsin transmittance than luminous transmittance). Across the data set, we find that melanopsin transmittance and luminous transmittance are correlated. CONCLUSIONS: We suggest that future studies and examinations of the physiological effects of optical filters quantify the visual and non-visual effects of the filters beyond the spectral transmittance, which will eventually aid in developing a mechanistic understanding of how different filters affect physiology. We strongly discourage comparing the downstream effects of different filters on, e.g. sleep or circadian responses, without considering their effects on the retinal stimulus.


Assuntos
Luz , Óptica e Fotônica , Estimulação Luminosa/métodos , Retina/fisiologia , Visão Ocular/fisiologia , Humanos , Opsinas de Bastonetes/metabolismo , Opsinas de Bastonetes/efeitos da radiação
4.
Anal Bioanal Chem ; 411(29): 7637-7643, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31701209

RESUMO

ColiSense, an early warning system developed for Escherichia coli detection, is assessed using environmental samples. The system relies on the detection of ß-glucuronidase (GUS), a biomarker enzyme for E. coli. In contrast with other rapid GUS-based methods, ColiSense is the only method that uses 6-chloro-4-methyl-umbelliferyl-ß-D-glucuronide (6-CMUG) as a fluorogenic substrate. The system measures a direct kinetic response of extracted GUS, and the detection was carried out in the absence of particles or bacteria. It is necessary to evaluate the system with environmental samples to establish the relationship between faecal indicator bacteria E. coli and the response measured by the ColiSense. This paper presents the results of tests carried out with the ColiSense system for 2 trials, one conducted with freshwater samples collected from rivers in the Dublin area and a second conducted with seawater samples from coastal areas collected over the bathing season. A positive linear correlation was found between E. coli (MPN 100 mL-1) and ColiSense response (R2 = 0.85, N = 125, p < 0.01) for the seawater sample. A ColiSense response threshold was identified as 0-1.8 pmol min-1 100 mL-1, equivalent to 0-500 E. coli 100 mL-1. Using this threshold, 96.8% of the samples were correctly classified as being above or below 500 E. coli 100 mL-1 by the ColiSense system. Results presented demonstrate that the ColiSense system can be used as an early warning tool with potential for active management of bathing areas by providing results in 75 min from sample collection.


Assuntos
Técnicas Biossensoriais/instrumentação , Escherichia coli/isolamento & purificação , Fezes/microbiologia , Água Doce/microbiologia , Glucuronidase/metabolismo , Óptica e Fotônica , Água do Mar/microbiologia , Biomarcadores/metabolismo , Escherichia coli/enzimologia , Microbiologia da Água
5.
Phys Rev Lett ; 123(16): 163901, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31702361

RESUMO

When the feature size of photonic structures becomes comparable or even smaller than the wavelength of light, the fabrication imperfections inevitably introduce disorder that may eliminate many functionalities of subwavelength photonic devices. Here we suggest a novel concept to achieve a robust band gap which can endure disorder beyond 30% as a result of the transition from photonic crystals to Mie-resonant metamaterials. By utilizing Mie-resonant metamaterials with high refractive index, we demonstrate photonic waveguides and cavities with strong robustness to position disorder, thus providing a novel approach to the band-gap-based nanophotonic devices with new properties and functionalities.


Assuntos
Modelos Teóricos , Óptica e Fotônica/métodos , Fótons
6.
Nature ; 574(7779): 491-492, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31645716
7.
Nat Commun ; 10(1): 4264, 2019 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-31537802

RESUMO

Graded index (GRIN) lenses are commonly used for compact imaging systems. It is not widely appreciated that the ion-exchange process that creates the rotationally symmetric GRIN lens index profile also causes a symmetric birefringence variation. This property is usually considered a nuisance, such that manufacturing processes are optimized to keep it to a minimum. Here, rather than avoiding this birefringence, we understand and harness it by using GRIN lenses in cascade with other optical components to enable extra functionality in commonplace GRIN lens systems. We show how birefringence in the GRIN cascades can generate vector vortex beams and foci, and how it can be used advantageously to improve axial resolution. Through using the birefringence for analysis, we show that the GRIN cascades form the basis of a new single-shot Müller matrix polarimeter with potential for endoscopic label-free cancer diagnostics. The versatility of these cascades opens up new technological directions.


Assuntos
Endoscopia/instrumentação , Lentes , Neoplasias/diagnóstico por imagem , Óptica e Fotônica , Polarimetria de Varredura a Laser/instrumentação , Birrefringência , Neoplasias/diagnóstico , Refratometria , Polarimetria de Varredura a Laser/métodos
8.
Opt Express ; 27(16): 23378-23395, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31510616

RESUMO

Fluorescence correlation spectroscopy in combination with super-resolution stimulated emission depletion microscopy (STED-FCS) is a powerful tool to investigate molecular diffusion with sub-diffraction resolution. It has been of particular use for investigations of two dimensional systems like cell membranes, but has so far seen very limited applications to studies of three-dimensional diffusion. One reason for this is the extreme sensitivity of the axial (z) STED depletion pattern to optical aberrations. We present here an adaptive optics-based correction method that compensates for these aberrations and allows STED-FCS measurements in the cytoplasm of living cells.


Assuntos
Citoplasma/metabolismo , Microscopia de Fluorescência/métodos , Óptica e Fotônica , Espectrometria de Fluorescência/métodos , Sobrevivência Celular , Difusão , Humanos , Soluções
9.
BMC Ophthalmol ; 19(1): 187, 2019 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-31426775

RESUMO

BACKGROUND: To evaluate the clinical outcomes of extended depth of focus (EDOF) and monofocal intraocular lenses (IOLs) that share identical aspheric platform and compare their visual acuity tolerance to postoperative refractive errors. METHODS: This non-randomized, prospective comparative study included 120 eyes undergoing cataract surgery with implantation of either Tecnis ZCB00 IOL (Abbott Medical Optics Inc., Santa Ana, CA) (monofocal group: 60 eyes of 30 patients) or Tecnis Symfony IOL (Abbott Medical Optics, Inc.) (EDOF group: 60 eyes of 30 patients). Monocular and binocular visual outcomes, changes in refraction, defocus curve, contrast sensitivity, and perception of photic phenomena (Halo & Glare Simulator; Eyeland Design Network, Vreden, Germany) were evaluated 3 months postoperatively. To compare the refractive tolerance, each group was divided into three subgroups according to the postoperative uncorrected distance visual acuity (UDVA) and postoperative spherical equivalent (SE). RESULTS: In the EDOF group, the mean 3-months postoperative monocular UDVA, intermediate (UIVA), and near (UNVA) visual acuities were 0.03 ± 0.07, 0.09 ± 0.15, and 0.24 ± 0.16 logMAR, respectively. A total of 100, 96.55, and 68.97% of eyes in the EDOF group achieved binocular UDVA, UIVA, and UNVA values of 0.20 logMAR or better, respectively. In respect to refractive tolerance, the EDOF group showed higher SE values and statistically significantly better mean UDVA than the monofocal group in all subgroups, with UDVA of - 0.013 and 0.028 logMAR for EDOF and monofocal groups (p = 0.037), respectively, in the subgroup where SE was within ±0.50 D, UDVA of 0.004 and 0.048 logMAR for EDOF and monofocal groups (p = 0.046), respectively, in the subgroup where SE was within - 1.00 D, and UDVA of 0.020 and 0.083 logMAR for EDOF and monofocal groups (p = 0.026), respectively, in the subgroup where SE was more than - 1.00 D. The mean patient satisfaction scores for spectacle-free distance, intermediate, and near visual acuities were 86.0, 85.0, and 66.0, respectively. CONCLUSIONS: The EDOF IOL provided excellent postoperative visual outcomes in far and intermediate distances, with high patient satisfaction rate. Regarding the postoperative refractive tolerance to SE, the Tecnis Symfony IOL showed better tolerance to residual postoperative refractive error than the monofocal IOL with the same material and optical platform.


Assuntos
Percepção de Profundidade/fisiologia , Lentes Intraoculares , Óptica e Fotônica , Refração Ocular/fisiologia , Erros de Refração/fisiopatologia , Acuidade Visual , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Satisfação do Paciente , Facoemulsificação , Período Pós-Operatório , Estudos Prospectivos , Erros de Refração/epidemiologia , República da Coreia/epidemiologia
10.
Sensors (Basel) ; 19(17)2019 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-31450817

RESUMO

Waveguide-based photonic sensors provide a unique combination of high sensitivity, compact size and label-free, multiplexed operation. Interferometric configurations furthermore enable a simple, fixed-wavelength read-out making them particularly suitable for low-cost diagnostic and monitoring devices. Their limit of detection, i.e., the lowest analyte concentration that can be reliably observed, mainly depends on the sensors response to small refractive index changes, and the noise in the read-out system. While enhancements in the sensors response have been extensively studied, noise optimization has received much less attention. Here we show that order-of-magnitude enhancements in the limit of detection can be achieved through systematic noise reduction, and demonstrate a limit of detection of ∼ 10 - 8 RIU with a silicon nitride sensor operating at telecom wavelengths.


Assuntos
Técnicas Biossensoriais , Óptica e Fotônica/métodos , Compostos de Silício/isolamento & purificação , Interferometria , Limite de Detecção , Compostos de Silício/química
11.
Invest Ophthalmol Vis Sci ; 60(10): 3527-3536, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31412112

RESUMO

Purpose: To examine inner retinal hyperreflective features on adaptive optics scanning laser ophthalmoscopy (AOSLO) in individuals with early cognitive impairment. Methods: In this prospective, cross-sectional study, we enrolled 12 participants with either amnestic mild cognitive impairment (aMCI, n = 10) or early dementia due to Alzheimer's disease (eAD, n = 2) and 12 age-, sex-, and race-matched cognitively normal controls. All participants completed AOSLO imaging of the inner retina. AOSLO montages of the peripapillary area were graded for hyperreflective features including granular membranes, mottled membranes, and nummular features. Regions of interest on AOSLO were compared qualitatively to corresponding optical coherence tomography (OCT) cross sections. OCT was also used to analyze peripapillary retinal nerve fiber layer (RNFL) thickness. Results: Cognitively impaired individuals had a significantly higher number of granular membranes with a larger overall area compared to controls. The proportion of cognitively impaired individuals with two or more granular membranes was 41.7% compared to none in the control group. Granular membrane area was also inversely correlated with cognitive performance on the Montreal Cognitive Assessment. There was no difference between the two groups in terms of other membrane types or RNFL thickness. Conclusions: Individuals with early cognitive impairment related to Alzheimer's show hyperreflective granular membranes on high-resolution imaging, which we hypothesize to be manifestations of inner retinal gliosis. The presence of these subtle hyperreflective membranes may obscure underlying RNFL thinning in these eyes on OCT imaging. The distinctive phenotype of granular membranes surrounding the optic nerve on AOSLO may represent a new potential biomarker of early Alzheimer's.


Assuntos
Doença de Alzheimer/diagnóstico , Disfunção Cognitiva/diagnóstico , Gliose/diagnóstico , Doenças Retinianas/diagnóstico , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Fibras Nervosas/patologia , Oftalmoscopia/métodos , Óptica e Fotônica , Estudos Prospectivos , Células Ganglionares da Retina/patologia , Tomografia de Coerência Óptica/métodos
12.
Biosens Bioelectron ; 143: 111596, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31442754

RESUMO

Plasmonic-dielectic hybrid substrates of Ag-islands on three-dimensional photonic crystals are fabricated through magnetron sputtering of silver onto hydrophobized silica photonic crystals, free from etching process. Without typical "hot-spots" such as nanogaps, significant Raman enhancements can be achieved, attributed to the enhanced electromagnetic field and scattering of the plasmonic nanoparticles as well as the enhanced light-matter interaction by the slow photon effects. The detection limit for adenine by the hybrid substrates reaches nM level, with a calculated enhancement factor of 1.13 × 107, which is three orders of magnitude higher than the conventional noble metal film over nanosphere (FON) control group. Furthermore, microchips based on the hybrid substrates are facilely achieved, enabling micro-detection through super hydrophobic concentration. The facile fabrication and effective Raman enhancements make the Ag-islands on 3D photonic crystals promising candidates in the field of chemical sensors, Raman mapping and bioassays.


Assuntos
Adenina/isolamento & purificação , Técnicas Biossensoriais , Nanopartículas Metálicas/química , Óptica e Fotônica , Adenina/química , Campos Eletromagnéticos , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Nanosferas/química , Nanoestruturas/química , Dióxido de Silício/química , Análise Espectral Raman , Propriedades de Superfície
13.
IEEE Int Conf Rehabil Robot ; 2019: 139-144, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31374620

RESUMO

Wearable sensors provide a foundation for development of wearable robotic technology to be used in clinical applications. Inertial motion capture (IMC) has emerged as a viable alternative to more cumbersome, non-portable optical methods. Previous work has validated the accuracy of IMC for gait compared to optical motion capture (OMC). However, it is unclear how well IMC can measure the small changes in gait function needed to gauge recovery. In this study, we evaluate the sensitivity of IMC compared to OMC to small changes in gait on a cohort of unimpaired individuals during treadmill walking. Eight individuals walked on a split-belt treadmill in three-minute trials with five randomized conditions: right belt speed decrementing at 0.05 m/s from 1.0 m/s, all with left belt held at 1.0 m/s, simulating recovery of hemiparetic gait. We extracted the root mean square deviation (RMSD) of joint kinematics between limbs and within the limb with modulated gait speed as the main outcome measure. We used linear mixed models to identify differences in sensitivity to changes in gait asymmetry and gait speed. Based on these models, we estimated the minimal detectible interval in gait parameters. We found that IMC was capable of measuring a difference in gait speed of 0.08 m/s, roughly the equivalent of two weeks recovery progress. Statistically we could not conclude a difference of sensitivity between IMC and OMC, although there is a strong trend that IMC is more sensitive to changes in gait. We conclude that IMC is a valid tool to measure progress in gait kinematics over the course of recovery.


Assuntos
Marcha/fisiologia , Movimento (Física) , Óptica e Fotônica , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Articulação do Joelho/fisiologia , Masculino , Velocidade de Caminhada , Adulto Jovem
14.
Anal Bioanal Chem ; 411(29): 7717-7724, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31392435

RESUMO

This work reports on further development of an optical biosensor for the in vitro detection of mycotoxins (in particular, aflatoxin B1) using a highly sensitive planar waveguide transducer in combination with a highly specific aptamer bioreceptor. This sensor is built on a SiO2-Si3N4-SiO2 optical planar waveguide (OPW) operating as a polarization interferometer (PI), which detects a phase shift between p- and s-components of polarized light propagating through the waveguide caused by the molecular adsorption. The refractive index sensitivity (RIS) of the recently upgraded PI experimental setup has been improved and reached values of around 9600 rad per refractive index unity (RIU), the highest RIS values reported, which enables the detection of low molecular weight analytes such as mycotoxins in very low concentrations. The biosensing tests yielded remarkable results for the detection of aflatoxin B1 in a wide range of concentrations from 1 pg/mL to 1 µg/mL in direct assay with specific DNA-based aptamers. Graphical abstract Optical planar waveguide polarization interferometry biosensor for detection of aflatoxin B1 using specific aptamer.


Assuntos
Aflatoxina B1/análise , Aptâmeros de Nucleotídeos/química , Interferometria/métodos , Técnicas Biossensoriais , Técnicas In Vitro , Limite de Detecção , Ocratoxinas/análise , Óptica e Fotônica , Refratometria , Dióxido de Silício/química
15.
Biomed Res Int ; 2019: 6425040, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31346522

RESUMO

The number of presbyopia correcting intraocular lenses (IOLs) is increasing and new technologies are constantly emerging with the aim of correcting the loss of accommodation after cataract surgery. Various optical designs have been proposed to implement multifocality or an extended depth of focus (EDOF). Depending on the optical principle of an implanted lens, the visual performance often is deteriorated by superposition of individual image planes and halos of varying intensity. This experimental study presents a concept to visualize the light fields and especially the halos of mono- and multifocal IOLs using the well known alcoholic beverage "ouzo" in order to obtain qualitative data on the imaging characteristics. We conclude that ouzo is a useful, cost effective, and nonpolluting medium for beam visualization and an alternative to fluorescein or milk, which could find an application for educational purposes.


Assuntos
Acomodação Ocular/fisiologia , Extração de Catarata/métodos , Catarata/terapia , Lentes Intraoculares Multifocais , Catarata/fisiopatologia , Humanos , Luz , Óptica e Fotônica/métodos , Visão Ocular/fisiologia , Acuidade Visual/fisiologia
16.
Rom J Ophthalmol ; 63(2): 153-160, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31334394

RESUMO

Purpose: To assess the variation in cone photoreceptor density on the basis of age compatibility between healthy subjects, on one side, and type 1 diabetic patients with no diabetic retinopathy, on the other. Methods: A high resolution adaptive optics retinal camera in flood illumination regime was employed to image cones of 15 type I diabetic patients and 16 healthy controls. For each subject we scanned the cone mosaic in 4 perifoveal areas (nasally, temporally, superiorly and inferiorly) at 2, 3 and 4 degrees eccentricity. The impact of diabetes duration, gender and age were evaluated. Results: In the type I diabetic group we found a meaningful lower cone density (p<0.05), except for the temporal meridian at 2 and 4 degrees eccentricity. Moreover, a significant asymmetry of cone photoreceptor densities was proved between the horizontal and vertical meridians in both diabetic and control groups. Conclusion: The rtx1 retinal image evaluation demonstrated photoreceptors loss in DM1 diabetic patients prior to any clinical changes. Abbreviations: AO = adaptive optics, SS = swept source, OCT = optical coherence tomography, BCVA= best corrected visual acuity, DM = diabetes mellitus, DR = diabetic retinopathy.


Assuntos
Diabetes Mellitus Tipo 1/patologia , Oftalmoscopia/métodos , Óptica e Fotônica , Células Fotorreceptoras Retinianas Cones/patologia , Tomografia de Coerência Óptica/instrumentação , Adolescente , Adulto , Contagem de Células , Desenho de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Acuidade Visual , Adulto Jovem
17.
Molecules ; 24(13)2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31269660

RESUMO

Pesticides vary in the level of poisonousness, while a conventional rapid test card only provides a general "absence or not" solution, which cannot identify the various genera of pesticides. In order to solve this problem, we proposed a seven-layer paper-based microfluidic chip, integrating the enzyme acetylcholinesterase (AChE) and chromogenic reaction. It enables on-chip pesticide identification via a reflected light intensity spectrum in time-sequence according to the different reaction efficiencies of pesticide molecules and assures the optimum temperature for enzyme activity. After pretreatment of figures of reflected light intensity during the 15 min period, the figures mainly focused on the reflected light variations aroused by the enzyme inhibition assay, and thus, the linear discriminant analysis showed satisfying discrimination of imidacloprid (Y = -1.6525X - 139.7500), phorate (Y = -3.9689X - 483.0526), and avermectin (Y = -2.3617X - 28.3082). The correlation coefficients for these linearity curves were 0.9635, 0.8093, and 0.9094, respectively, with a 95% limit of agreement. Then, the avermectin class chemicals and real-world samples (i.e., lettuce and rice) were tested, which all showed feasible graphic results to distinguish all the chemicals. Therefore, it is feasible to distinguish the three tested kinds of pesticides by the changes in the reflected light spectrum in each min (15 min) via the proposed chip with a high level of automation and integration.


Assuntos
Inibidores Enzimáticos/análise , Dispositivos Lab-On-A-Chip , Óptica e Fotônica/métodos , Papel , Resíduos de Praguicidas/análise , Análise por Conglomerados , Ivermectina/análogos & derivados , Ivermectina/análise , Ivermectina/química , Neonicotinoides/análise , Neonicotinoides/química , Nitrocompostos/análise , Nitrocompostos/química , Forato/análise , Forato/química , Fatores de Tempo
18.
Molecules ; 24(13)2019 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-31277470

RESUMO

In recent years, the development of metamaterials and metasurfaces has drawn great attention, enabling many important practical applications. Focusing and lensing components are of extreme importance because of their significant potential practical applications in biological imaging, display, and nanolithography fabrication. Metafocusing devices using ultrathin structures (also known as metasurfaces) with superlensing performance are key building blocks for developing integrated optical components with ultrasmall dimensions. In this article, we review the metamaterial superlensing devices working in transmission mode from the perfect lens to two-dimensional metasurfaces and present their working principles. Then we summarize important practical applications of metasurfaces, such as plasmonic lithography, holography, and imaging. Different typical designs and their focusing performance are also discussed in detail.


Assuntos
Lentes , Nanotecnologia , Óptica e Fotônica , Prata/química , Propriedades de Superfície
19.
Sensors (Basel) ; 19(14)2019 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-31336702

RESUMO

Photonic nanoarchitectures in the wing scales of butterflies and moths are capable of fast and chemically selective vapor sensing due to changing color when volatile vapors are introduced to the surrounding atmosphere. This process is based on the capillary condensation of the vapors, which results in the conformal change of the chitin-air nanoarchitectures and leads to a vapor-specific optical response. Here, we investigated the optical responses of the wing scales of several butterfly and moth species when mixtures of different volatile vapors were applied to the surrounding atmosphere. We found that the optical responses for the different vapor mixtures fell between the optical responses of the two pure solvents in all the investigated specimens. The detailed evaluation, using principal component analysis, showed that the butterfly-wing-based sensor material is capable of differentiating between vapor mixtures as the structural color response was found to be characteristic for each of them.


Assuntos
Borboletas , Mariposas , Compostos Orgânicos Voláteis , Asas de Animais/química , Asas de Animais/fisiologia , Ácido Acético/análise , Ácido Acético/química , Animais , Borboletas/fisiologia , Etanol , Masculino , Mariposas/fisiologia , Óptica e Fotônica , Pigmentação , Análise de Componente Principal , Espectrofotometria/instrumentação , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química , Asas de Animais/anatomia & histologia
20.
Int J Mol Sci ; 20(15)2019 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-31357727

RESUMO

Magnetic fluid is a stable colloidal suspension of nano-sized, single-domain ferri/ferromagnetic particles dispersed in a liquid carrier. The liquid can be magnetized by the ferromagnetic particles aligned with the external magnetic field, which can be used as a wavefront corrector to correct the large aberrations up to more than 100 µm in adaptive optics (AO) systems. Since the measuring range of the wavefront sensor is normally small, the application of the magnetic fluid deformable mirror (MFDM) is limited with the WFS based AO system. In this paper, based on the MFDM model and the relationship between the second moment (SM) of the aberration gradients and the far-field intensity distribution, a model-based wavefront sensorless (WFSless) control algorithm is proposed for the MFDM. The correction performance of MFDM using the model-based control algorithm is evaluated in a WFSless AO system setup with a prototype MFDM, where a laser beam with unknown aberrations is supposed to produce a focused spot on the CCD. Experimental results show that the MFDM can be used to effectively compensate for unknown aberrations in the imaging system with the proposed model-based control algorithm.


Assuntos
Coloides/química , Nanopartículas de Magnetita/química , Imãs/química , Algoritmos , Fenômenos Magnéticos , Óptica e Fotônica
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA