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1.
J Breath Res ; 14(4): 043001, 2020 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-32969348

RESUMO

Cavity-enhanced absorption spectroscopies (CEAS) have gained importance in a wide range of applications in molecular spectroscopy. The development of optical sensors based on the CEAS techniques coupled with the continuous wave or pulsed laser sources operating in the mid-infrared or near-infrared spectral regime uniquely offers molecularly selective and ultra-sensitive detection of trace species in complex matrices including exhaled human breath. In this review, we discussed recent applications of CEAS for analyzing trace constituents within the exhaled breath matrix facilitating the non-invasive assessment of human health status. Next to a brief discussion on the mechanisms of formation of trace components found in the exhaled breath matrix related to particular disease states, existing challenges in CEAS and future development towards non-invasive clinical diagnostics will be discussed.


Assuntos
Testes Respiratórios/métodos , Expiração , Óptica e Fotônica/métodos , Animais , Humanos , Óxido Nítrico/análise , Consumo de Oxigênio , Espectroscopia de Luz Próxima ao Infravermelho
2.
Nat Commun ; 11(1): 4108, 2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32796840

RESUMO

Replicating biological patterns is promising for designing materials with multifaceted properties. Twisted cholesteric liquid crystal patterns are found in the iridescent tessellated cuticles of many insects and a few fruits. Their accurate replication is extremely difficult since discontinuous patterns and colors must coexist in a single layer without discontinuity of the structures. Here, a solution is demonstrated by addressing striped insect cuticles with a complex twisted organization. Geometric constraints are met by controlling the thermal diffusion in a cholesteric oligomer bilayer subjected to local changes in the molecular anchoring conditions. A multicriterion comparison reveals a very high level of biomimicry. Proof-of-concept prototypes of anti-counterfeiting tags are presented. The present design involves an economy of resources and a high versatility of chiral patterns unreached by the current manufacturing techniques such as metallic layer vacuum deposition, template embossing and various forms of lithography which are limited and often prohibitively expensive.


Assuntos
Biomimética/métodos , Biofísica/métodos , Cristais Líquidos/química , Óptica e Fotônica/métodos , Animais , Insetos
3.
Comput Methods Biomech Biomed Engin ; 23(14): 1127-1137, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32657618

RESUMO

Contraction due to polymerization of dental resin can cause failure on the adhesive interfaces, can lead to problems such as the appearance of gaps in the interfaces, postoperative sensitivity, pulp damage and the return of the caries. The objective of this work is the study of stresses on the dental adhesive that are generated by the process shrinkage of resin associated with biting forces. A laboratory experiment measured the strains and temperature inside the FiltekTM Bulk Fill Flow resin during the process of polymerization using Fiber Bragg Grating sensors in an ex vivo tooth. From tomographic images a three-dimensional geometric model of the tooth was reconstructed. A pre-tension was calibrated to simulate the residual contraction on the resin 3 D model. Finally, an Finite Element Method analysis was performed to access the adhesive stresses at the interface enamel/dentin with the adhesive, considering as loading the residual polymerization contraction of the dental resin and also biting loads. The model was able to represented the strain obtained in the laboratory experiment. The results of the stress analysis shows that the outer regions of adhesive are more prone to failure, as veried by dental surgeons in clinical practice.


Assuntos
Resinas Compostas/química , Análise de Elementos Finitos , Óptica e Fotônica/métodos , Adulto , Fenômenos Biomecânicos , Força de Mordida , Calibragem , Colagem Dentária , Análise do Estresse Dentário , Humanos , Imageamento Tridimensional , Teste de Materiais , Polimerização , Pressão , Temperatura , Adulto Jovem
4.
Proc Natl Acad Sci U S A ; 117(29): 17260-17268, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32632007

RESUMO

Understanding how a network of interconnected neurons receives, stores, and processes information in the human brain is one of the outstanding scientific challenges of our time. The ability to reliably detect neuroelectric activities is essential to addressing this challenge. Optical recording using voltage-sensitive fluorescent probes has provided unprecedented flexibility for choosing regions of interest in recording neuronal activities. However, when recording at a high frame rate such as 500 to 1,000 Hz, fluorescence-based voltage sensors often suffer from photobleaching and phototoxicity, which limit the recording duration. Here, we report an approach called electrochromic optical recording (ECORE) that achieves label-free optical recording of spontaneous neuroelectrical activities. ECORE utilizes the electrochromism of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films, whose optical absorption can be modulated by an applied voltage. Being based on optical reflection instead of fluorescence, ECORE offers the flexibility of an optical probe without suffering from photobleaching or phototoxicity. Using ECORE, we optically recorded spontaneous action potentials in cardiomyocytes, cultured hippocampal and dorsal root ganglion neurons, and brain slices. With minimal perturbation to cells, ECORE allows long-term optical recording over multiple days.


Assuntos
Eletrofisiologia/métodos , Neurônios/fisiologia , Poliestirenos , Tiofenos , Potenciais de Ação/fisiologia , Encéfalo/citologia , Encéfalo/fisiologia , Técnicas Eletroquímicas/métodos , Fenômenos Eletrofisiológicos , Corantes Fluorescentes , Gânglios Espinais/citologia , Gânglios Espinais/fisiologia , Humanos , Imagem Óptica , Óptica e Fotônica/métodos
5.
Sensors (Basel) ; 20(7)2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32260312

RESUMO

This paper analyzes, through computational simulations, which spectral filters increase the number of discernible colors (NODC) of subjects with normal color vision, as well as red-green anomalous trichromats and dichromats. The filters are selected from a set of filters in which we have modeled spectral transmittances. With the selected filters we have carried out simulations performed using the spectral reflectances captured either by a hyperspectral camera or by a spectrometer. We have also studied the effects of these filters on color coordinates. Finally, we have simulated the results of two widely used color blindness tests: Ishihara and Farnsworth-Munsell 100 Hue (FM100). In these analyses the selected filters are compared with the commercial filters from EnChroma and VINO companies. The results show that the increase in NODC with the selected filters is not relevant. The simulation results show that none of these chosen filters help color vision deficiency (CVD) subjects to pass the set of color blindness tests studied. These results obtained using standard colorimetry support the hypothesis that the use of color filters does not cause CVDs to have a perception similar to that of a normal observer.


Assuntos
Percepção de Cores/fisiologia , Defeitos da Visão Cromática/reabilitação , Óptica e Fotônica/métodos , Defeitos da Visão Cromática/patologia , Filtração , Humanos , Dispositivos Ópticos , Óptica e Fotônica/instrumentação
6.
Appl Opt ; 59(4): 955-963, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32225232

RESUMO

Human body measurement is essential in modern rehabilitation medicine, which can be effectively combined with the technology of additive manufacturing. Digital image correlation based on laser speckle projection is a single-shot, accurate, and robust technique for human body measurement. In this paper, we present a handheld anthropometric measurement system based on laser speckle projection. A flexible retroreflective marker target is designed for multi-view data registration. Meanwhile, a synchronous redundancy-reduction algorithm based on a re-projected global disparity map is proposed. Experiment results validate that the proposed system is effective and accurate for different human body part measurements. Comparative experiments show that the proposed redundancy-reduction algorithm has high efficiency and can effectively preserve the features of complex shapes. The comprehensive performance of the algorithm is better than the other two tested methods.


Assuntos
Antropometria/instrumentação , Antropometria/métodos , Diagnóstico por Imagem/instrumentação , Diagnóstico por Imagem/métodos , Algoritmos , Simulação por Computador , Humanos , Processamento de Imagem Assistida por Computador , Lasers , Modelos Biológicos , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Imagens de Fantasmas
7.
Opt Express ; 28(7): 10491-10504, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-32225632

RESUMO

Temperature cross-sensitivity is a long-standing challenge for most of the in-line fiber optofluidic waveguide biosensors. In this paper, we propose a dual-optofluidic waveguide antiresonant reflecting optical waveguide (ARROW) biosensor for the detection of interferon-gamma (IFN-γ) concentration with temperature compensation. Two Fabry-Perot resonators infiltrated with IFN-γ and NaCl were formed in a hollow core fiber, which generate two resonance dips based on the ARROW model. The optical biosensor for the detection of interferon-gamma (IFN-γ) has been a key research interest in recent years because IFN-γ is an important early biomarker for many serious human diseases. Based on the dual-optofluidic waveguide ARROW biosensor, the IFN-γ concentration can be measured through the modulation of the resonance condition of the ARROW, while the temperature fluctuation can be eliminated due to same thermo-optic coefficients of two infiltration liquids. The experimental results show that the response of the ARROW biosensor can be amplified significantly with the signal-enhanced streptavidin, and the limit of detection of 0.5 ng/ml can be achieved for the IFN-γ concentration. More importantly, the influence of the temperature could be compensated through the referenced resonance dip. The proposed fiber biosensor has a great potential for the real-time detection of IFN-γ concentrations in the fields of health monitoring, cancer prevention, biological engineering, etc.


Assuntos
Técnicas Biossensoriais/instrumentação , Interferon gama/análise , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Temperatura , Aptâmeros de Nucleotídeos/química , Tecnologia de Fibra Óptica , Humanos , Processamento de Sinais Assistido por Computador , Coloração e Rotulagem , Estreptavidina/química
8.
Sci Rep ; 10(1): 6098, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32269249

RESUMO

In today's data-driven world, the ability to process large data volumes is crucial. Key tasks, such as pattern recognition and image classification, are well suited for artificial neural networks (ANNs) inspired by the brain. Neuromorphic computing approaches aimed towards physical realizations of ANNs have been traditionally supported by micro-electronic platforms, but recently, photonic techniques for neuronal emulation have emerged given their unique properties (e.g. ultrafast operation, large bandwidths, low cross-talk). Yet, hardware-friendly systems of photonic spiking neurons able to perform processing tasks at high speeds and with continuous operation remain elusive. This work provides a first experimental report of Vertical-Cavity Surface-Emitting Laser-based spiking neurons demonstrating different functional processing tasks, including coincidence detection and pattern recognition, at ultrafast rates. Furthermore, our approach relies on simple hardware implementations using off-the-shelf components. These results therefore hold exciting prospects for novel, compact and high-speed neuromorphic photonic platforms for future computing and Artificial Intelligence systems.


Assuntos
Redes Neurais de Computação , Óptica e Fotônica/métodos , Reconhecimento Automatizado de Padrão/métodos , Lasers , Óptica e Fotônica/instrumentação , Semicondutores
9.
Food Chem ; 318: 126461, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32143129

RESUMO

A sensor consisting of an optical fibre with the exposed tip coated with the polyoxometalate salt [(C4H9)4N]4H[PMo10V2O40], specially designed to be insoluble in water, which UV-Vis spectrum changed in contact with formaldehyde, is presented. The sensor limit of detection for formaldehyde was 0.2 mg L-1, and the limit of quantification was 0.6 mg L-1, which were close to the conventional spectrophotometric method values of 0.2 mg L-1 and 0.5 mg L-1, respectively, and lower than the tolerable limit for ingested food. The sensor was tested for formaldehyde quantification in milk, as its deliberate addition is a matter of concern. The results obtained analysing formaldehyde in milk samples by the optical sensor and by the conventional method were not statistically different (α = 0.05).


Assuntos
Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Formaldeído/análise , Leite/química , Fibras Ópticas , Animais , Limite de Detecção , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Compostos de Tungstênio/química , Água/química
10.
Sci Adv ; 6(11): eaay1729, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32201718

RESUMO

Recent advancements in electronic packaging and image processing techniques have opened the possibility for optics-based portable eye tracking approaches, but technical and safety hurdles limit safe implementation toward wearable applications. Here, we introduce a fully wearable, wireless soft electronic system that offers a portable, highly sensitive tracking of eye movements (vergence) via the combination of skin-conformal sensors and a virtual reality system. Advancement of material processing and printing technologies based on aerosol jet printing enables reliable manufacturing of skin-like sensors, while the flexible hybrid circuit based on elastomer and chip integration allows comfortable integration with a user's head. Analytical and computational study of a data classification algorithm provides a highly accurate tool for real-time detection and classification of ocular motions. In vivo demonstration with 14 human subjects captures the potential of the wearable electronics as a portable therapy system, whose minimized form factor facilitates seamless interplay with traditional wearable hardware.


Assuntos
Convergência Ocular , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Telemedicina/instrumentação , Telemedicina/métodos , Realidade Virtual , Dispositivos Eletrônicos Vestíveis , Tecnologia sem Fio , Técnicas Biossensoriais , Humanos , Processamento de Sinais Assistido por Computador
11.
Nat Commun ; 11(1): 1495, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32198383

RESUMO

Imaging of complex (biological) samples in the near-infrared (NIR) is beneficial due to reduced light scattering, absorption, phototoxicity, and autofluorescence. However, there are few NIR fluorescent materials known and suitable for biomedical applications. Here we exfoliate the layered pigment CaCuSi4O10 (Egyptian Blue, EB) via ball milling and facile tip sonication into NIR fluorescent nanosheets (EB-NS). The size of EB-NS can be tailored to diameters <20 nm and heights down to 1 nm. EB-NS fluoresce at 910 nm and the fluorescence intensity correlates with the number of Cu2+ ions. Furthermore, EB-NS display no bleaching and high brightness compared with other NIR fluorophores. The versatility of EB-NS is demonstrated by in-vivo single-particle tracking and microrheology measurements in Drosophila melanogaster embryos. EB-NS can be uptaken by plants and remotely detected in a low-cost stand-off detection setup. In summary, EB-NS have the potential for a wide range of bioimaging applications.


Assuntos
Corantes Fluorescentes/efeitos da radiação , Raios Infravermelhos , Imagem Óptica/métodos , Óptica e Fotônica/métodos , Silicatos/efeitos da radiação , Animais , Cobre , Drosophila melanogaster/embriologia , Fluorescência , Íons , Modelos Teóricos , Nanopartículas
12.
Nat Commun ; 11(1): 710, 2020 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-32024847

RESUMO

To extend the imaging depth of high-resolution optical microscopy, various gating operations-confocal, coherence, and polarization gating-have been devised to filter out the multiply scattered wave. However, the imaging depth is still limited by the multiply scattered wave that bypasses the existing gating operations. Here, we present a space gating method, whose mechanism is independent of the existing methods and yet effective enough to complement them. Specifically, we reconstruct an image only using the ballistic wave that is acousto-optically modulated at the object plane. The space gating suppresses the multiply scattered wave by 10-100 times in a highly scattering medium, and thus enables visualization of the skeletal muscle fibers in whole-body zebrafish at 30 days post fertilization. The space gating will be an important addition to optical-resolution microscopy for achieving the ultimate imaging depth set by the detection limit of ballistic wave.


Assuntos
Microscopia Confocal/métodos , Óptica e Fotônica/métodos , Animais , Processamento de Imagem Assistida por Computador/métodos , Microscopia Confocal/instrumentação , Fibras Musculares Esqueléticas/citologia , Músculo Esquelético/diagnóstico por imagem , Óptica e Fotônica/instrumentação , Peixe-Zebra
13.
Sensors (Basel) ; 20(5)2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-32106464

RESUMO

Annual deaths in the U.S. attributed to diabetes are expected to increase from 280,210 in 2015 to 385,840 in 2030. The increase in the number of people affected by diabetes has made it one of the major public health challenges around the world. Better management of diabetes has the potential to decrease yearly medical costs and deaths associated with the disease. Non-invasive methods are in high demand to take the place of the traditional finger prick method as they can facilitate continuous glucose monitoring. Research groups have been trying for decades to develop functional commercial non-invasive glucose measurement devices. The challenges associated with non-invasive glucose monitoring are the many factors that contribute to inaccurate readings. We identify and address the experimental and physiological challenges and provide recommendations to pave the way for a systematic pathway to a solution. We have reviewed and categorized non-invasive glucose measurement methods based on: (1) the intrinsic properties of glucose, (2) blood/tissue properties and (3) breath acetone analysis. This approach highlights potential critical commonalities among the challenges that act as barriers to future progress. The focus here is on the pertinent physiological aspects, remaining challenges, recent advancements and the sensors that have reached acceptable clinical accuracy.


Assuntos
Acetona/análise , Técnicas Biossensoriais/métodos , Glicemia/análise , Testes Respiratórios/métodos , Eletricidade , Óptica e Fotônica/métodos , Humanos
14.
Sci Rep ; 10(1): 1418, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31996729

RESUMO

Coloration in insects provides a fruitful opportunity for interdisciplinary research involving both physics and biology, and for a better understanding of the design principles of biological structures. In this research we used nanometric and micrometric analyses to investigate the morphological and mechanical properties of the black-orange-black (BOB) color pattern in scelionid wasps, which has never been studied. The primary objective of the present investigation was to explore the structural and mechanical differences in the mesoscutum of four species: Baryconus with an orange mesosoma (i.e. BOB pattern), all black Baryconus, Scelio with an orange mesosoma (i.e. BOB pattern), and all black Scelio. The most outstanding findings include the absence of multilayer structures that generate structural color, a pigment concentrated in the upper surface of the epicuticle, and surprising differences between the four species. Three of the four species showed an accordion-like structure in the furrow (notaulus), whereas the adjacent mesoscutum was different in each species. Moreover, the normalized color component spectra for blue, green and red colors of the black mesoscutum of each genus showed the same spectral dependence while the orange color manifested small changes in the dominant wavelength, resulting in slightly different orange tones.


Assuntos
Biotecnologia/métodos , Nanotecnologia/métodos , Óptica e Fotônica/métodos , Vespas/química , Animais , Cor , Comunicação Interdisciplinar , Microscopia Eletrônica de Varredura , Microespectrofotometria , Vespas/ultraestrutura
15.
Eur J Ophthalmol ; 30(2): NP27-NP31, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30732462

RESUMO

PURPOSE: The etiology of torpedo maculopathy remains unknown, but it has been recently suggested that it could represent a persistent defect in the development of the retinal pigment epithelium. As retinal pigment epithelium and photoreceptors form a functional unit, an alteration of photoreceptor distribution or function is predictable. The aim of this study is to describe multimodal imaging, including adaptive optics, in three cases of torpedo maculopathy, and discuss its pathogenesis. METHODS: Multimodal imaging is presented, including fundus photographs, optical coherence tomography, adaptive optics, autofluorescence, fluorescein angiography, and ultra-widefield retinal imaging in three cases of torpedo maculopathy. RESULTS: An oval-shaped well-delimited chorioretinal lesion both hypopigmented centrally and with a hyperpigmented border in the temporal macula, consistent with torpedo maculopathy, was observed in three patients. Optical coherence tomography showed a preservation of the inner retina, a mild atrophy of the outer retina, an alteration of the ellipsoid zone and of the retinal pigment epithelium layer, and a neurosensory detachment. These lesions were hypoautofluorescent with a hyperautofluorescent border. Fluorescein angiography showed a hyperfluorescence by window effect. Adaptive optics imaging showed an alteration of the cone mosaic within the lesions, with a lower cone density and a higher spacing between cones. CONCLUSION: The alteration of the cone mosaic suggested by adaptive optics in torpedo maculopathy has never been described and could be explained by the alteration of the retinal pigment epithelium. Our results support the existing hypothesis on the pathogenesis of torpedo maculopathy that a persistent defect in the development of the retinal pigment epithelium may be responsible for this clinical entity.


Assuntos
Macula Lutea/patologia , Degeneração Macular/patologia , Imagem Multimodal , Adulto , Animais , Pré-Escolar , Feminino , Angiofluoresceinografia/métodos , Humanos , Degeneração Macular/diagnóstico por imagem , Óptica e Fotônica/métodos , Fotografação , Retina/patologia , Células Fotorreceptoras Retinianas Cones/patologia , Epitélio Pigmentado da Retina/patologia , Tomografia de Coerência Óptica/métodos
16.
Med Biol Eng Comput ; 58(1): 67-74, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31745837

RESUMO

Presently, there is no convenient method to measure 24-h urinary Na excretion, which is an important index of daily Na intake, and 24-h urine collection involves a complex process. However, the Na-to-creatinine ratio (NCR) in spot urine has the potential to evaluate 24-h Na excretion and is useful for point-of-care testing. Thus, this study aimed to realize a near-infrared spectroscopic system to assess NCR in spot urine: (1) We attempted to estimate Na concentration using fewer than 10 wavelengths; (2) we calculated NCR using creatinine concentrations from our previous report and verified the NCR predictability. A calibration model was created using multi-linear regression analysis using 10 selected wavelengths in the range of Fourier-transform infrared spectrometer. Spot urine samples were obtained from healthy adults, and glucose powder was added to them to simulate diabetic samples. NCR was calculated using only six wavelengths, and the results confirmed the high accuracy of the estimated Na concentration even though inorganic components do not absorb near-infrared light. Our method enables to optically estimate NCR in spot urine, and it will be useful for point-of-care testing. Graphical abstract.


Assuntos
Óptica e Fotônica/métodos , Sistemas Automatizados de Assistência Junto ao Leito , Espectroscopia de Luz Próxima ao Infravermelho , Urinálise/métodos , Creatinina/urina , Glucose/análise , Humanos , Sódio/urina , Soluções , Adulto Jovem
17.
Biotechniques ; 68(1): 35-40, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31870165

RESUMO

In situ measurement to determine mammalian cell number in a non-invasive, non-destructive and reagent-free manner is needed to enable continuous cell manufacturing. An analytical method is presented for non-invasive cell counting by conducting multiwavelength spectral analysis of mammalian cells achieving a minimal detectable cell count of 62,500 at 295 nm. Light absorbance was insensitive to culture volume, giving an absolute cell count rather than a concentration. The activation state of cells was also considered. The study was extended to quantification within polymeric microcapsules as an advanced substrate for mammalian cell growth in bioreactor formats and resulted in an offset directly correlating with the absorbance maxima of the polymer. These studies provide feasibility for optical density as a simple end point to indirectly quantify mammalian cell number for continuous monitoring of cell cultures.


Assuntos
Contagem de Células/métodos , Óptica e Fotônica/métodos , Animais , Adesão Celular , Técnicas de Cultura de Células/métodos , Células Cultivadas , Humanos , Células Jurkat , Mamíferos , Células-Tronco Mesenquimais/citologia , Microesferas , Polietilenoglicóis/química , Espectrofotometria/instrumentação
18.
Chem Rev ; 119(24): 12279-12336, 2019 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-31793285

RESUMO

The extraordinary properties of biological materials often result from their sophisticated hierarchical structures. Through multilevel and cross-scale structural designs, biological materials offset the weakness of their individual building blocks and enhance performance at multiple length scales to match the multifunctional needs of organisms. One essential merit of hierarchical structure is that it can optimize the interfacial features of the "building blocks" at different length scales, from the molecular level to the macroscale. Understanding the roles of biological material interfaces (BMIs) on the determination of properties and functions of biological materials has become a growing interdisciplinary research area in recent years. A pivotal aim of these studies is to use BMIs as inspiration for developing bioinspired and biomimetic materials and devices with advanced structures and functions. Given these considerations, this review aims to comprehensively discuss the structure-property-function relationships of BMIs in nature. We particularly focus on the discussion of BMIs and their inspired materials from mechanical and optical perspectives because these two directions are the most well-investigated and closely related. The challenges and directions of design and fabrication of BMI-inspired mechanical and optical materials are also discussed. This review is expected to garner interest from advanced material communities as well as environmental, nanotechnology, food processing, and engineering fields.


Assuntos
Produtos Biológicos/química , Materiais Biomiméticos/química , Animais , Biomimética/métodos , Nanofibras/química , Óptica e Fotônica/métodos , Relação Estrutura-Atividade
19.
Nat Commun ; 10(1): 5672, 2019 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-31831746

RESUMO

Constructing colloidal particles into functional nanostructures, materials, and devices is a promising yet challenging direction. Many optical techniques have been developed to trap, manipulate, assemble, and print colloidal particles from aqueous solutions into desired configurations on solid substrates. However, these techniques operated in liquid environments generally suffer from pattern collapses, Brownian motion, and challenges that come with reconfigurable assembly. Here, we develop an all-optical technique, termed optothermally-gated photon nudging (OPN), for the versatile manipulation and dynamic patterning of a variety of colloidal particles on a solid substrate at nanoscale accuracy. OPN takes advantage of a thin surfactant layer to optothermally modulate the particle-substrate interaction, which enables the manipulation of colloidal particles on solid substrates with optical scattering force. Along with in situ optical spectroscopy, our non-invasive and contactless nanomanipulation technique will find various applications in nanofabrication, nanophotonics, nanoelectronics, and colloidal sciences.


Assuntos
Coloides/química , Nanoestruturas/química , Óptica e Fotônica/métodos , Fótons , Fenômenos Biofísicos , Movimento (Física) , Tamanho da Partícula , Tensoativos/química , Temperatura
20.
Molecules ; 24(23)2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31775342

RESUMO

Schiff base liquid crystals, known as [4-(hexyloxy)phenylimino)methyl]phenyl palmitate (IA), [4-(hexyloxy)phenylimino)methyl]phenyl oleate (IIA) and [4-(hexyloxy)phenylimino)methyl]phenyl linoleate (IIIA), were synthesized from palmitic, oleic, and linoleic natural fatty acids. The prepared compounds have been investigated for their thermal and optical behavior as well as phase formation using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Molecular structures of all studied compounds were confirmed via elemental analysis, FT-IR, 1H NMR, and 13C NMR. Smectic phase is the observed mesophase for all compounds; however, their type and range depend upon the terminal alkanoate chains attached to the phenyl ring. Computational calculations, Density functional theory (DFT), energy difference of the frontier molecular orbital (FMOs), as well as the thermodynamic parameters of different molecular configurations isomers were discussed. It was found that the mesophase behavior and the geometrical characteristics were affected by the degree of unsaturation of fatty terminal chains. Furthermore, the geometrical structure of the CH=N linkage plays an important role in the thermal stability and optical transition temperature.


Assuntos
Ésteres/química , Ácidos Graxos/química , Cristais Líquidos/química , Bases de Schiff/química , Varredura Diferencial de Calorimetria , Ésteres/síntese química , Ácidos Graxos/síntese química , Espectroscopia de Ressonância Magnética , Conformação Molecular , Estrutura Molecular , Óptica e Fotônica/métodos , Bases de Schiff/síntese química , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Temperatura de Transição
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