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1.
Nat Commun ; 12(1): 716, 2021 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-33514737

RESUMO

For over two decades photoacoustic imaging has been tested clinically, but successful human trials have been limited. To enable quantitative clinical spectroscopy, the fundamental issues of wavelength-dependent fluence variations and inter-wavelength motion must be overcome. Here we propose a real-time, spectroscopic photoacoustic/ultrasound (PAUS) imaging approach using a compact, 1-kHz rate wavelength-tunable laser. Instead of illuminating tissue over a large area, the fiber-optic delivery system surrounding an US array sequentially scans a narrow laser beam, with partial PA image reconstruction for each laser pulse. The final image is then formed by coherently summing partial images. This scheme enables (i) automatic compensation for wavelength-dependent fluence variations in spectroscopic PA imaging and (ii) motion correction of spectroscopic PA frames using US speckle tracking in real-time systems. The 50-Hz video rate PAUS system is demonstrated in vivo using a murine model of labelled drug delivery.


Assuntos
Sistemas Computacionais , Imagem Molecular/métodos , Técnicas Fotoacústicas/métodos , Análise Espectral/métodos , Animais , Desenho de Equipamento , Feminino , Processamento de Imagem Assistida por Computador , Lasers , Camundongos , Camundongos Nus , Modelos Animais , Imagem Molecular/instrumentação , Movimento (Física) , Fibras Ópticas , Imagens de Fantasmas , Técnicas Fotoacústicas/instrumentação , Análise Espectral/instrumentação , Ultrassonografia/instrumentação , Ultrassonografia/métodos
2.
Adv Exp Med Biol ; 1293: 481-491, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33398835

RESUMO

We have developed a Si opt-electro multifunctional neural probe with multiple waveguides and embedded optical fiber for highly accurate optical stimulation. The Si opt-electro multifunctional neural probe had 16 recording sites, three optical waveguides, and metal cover for suppressing light leakage. The other opt-electro multifunctional neural probe had an optical fiber in the trench of the probe shank, which leads to fewer damages to tissues. We evaluated the electrochemical properties of the recording sites and confirmed that the neural probe had suitable characteristics for neural recording. We also demonstrated the optical stimulation to the neurons expressing ChR2 using our probe. As a result, we succeeded in multisite optical stimulation and observed that no light leakage from the optical waveguides because of the metal cover. From in vivo experiments, we successfully recorded optically modulated local field potential using the fabricated Si neural probe with optical waveguides. Moreover, we applied current source density analysis to the recorded LFPs. As a result, we confirmed that the light-induced membrane current sinks in the locally stimulated area. The Si opto-electro multifunctional neural probe is one of the most versatile tools for optogenetics.


Assuntos
Fibras Ópticas , Optogenética , Metais , Neurônios , Estimulação Luminosa
3.
Adv Exp Med Biol ; 1293: 565-583, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33398843

RESUMO

Although multiphoton microscopy enables optical control and monitoring of neural activity with single cells resolution over a depth of several hundreds of micrometers, the scattering nature of the brain tissue requires implantable optical neural interfaces to access subcortical structures. If micro light-emitting devices (µLEDs) and solid-state waveguides represent important technological advancements for the field, multimodal optical fibers (MMFs) are still the most diffused tool in neuroscience labs to interface with deep regions of the brain. At a first glance, MMFs can be seen as very limited systems. However, new studies and discoveries in optics, photonics, and technological solutions for their application to neuroscience research have enabled applications of MMF where competing technologies fail. In this framework, the chapter starts with a description of optical neural interfaces based on MMF, with specific reference on recent works analyzing the performances of this approach to deliver and collect light from scattering tissue. The discussion then focuses on how peculiar features of MMFs can be exploited to obtain unconventional applications, including brain imaging through a single multimode fiber, multifunctional neural interfaces, and depth-resolved light delivery and functional fluorescence collection.


Assuntos
Neurociências , Fibras Ópticas , Diagnóstico por Imagem , Fluorescência , Óptica e Fotônica
4.
Sensors (Basel) ; 21(2)2021 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-33445436

RESUMO

Human breath is a biomarker of body fat metabolism and can be used to diagnose various diseases, such as diabetes. As such, in this paper, a vacuum ultraviolet (VUV) spectroscopy system is proposed to measure the acetone in exhaled human breath. A strong absorption acetone peak at 195 nm is detected using a simple system consisting of a deuterium lamp source, a hollow-core fiber gas cell, and a fiber-coupled compact spectrometer corresponding to the VUV region. The hollow-core fiber functions both as a long-path and an extremely small-volume gas cell; it enables us to sensitively measure the trace components of exhaled breath. For breath analysis, we apply multiple regression analysis using the absorption spectra of oxygen, water, and acetone standard gas as explanatory variables to quantitate the concentration of acetone in breath. Based on human breath, we apply the standard addition method to obtain the measurement accuracy. The results suggest that the standard deviation is 0.074 ppm for healthy human breath with an acetone concentration of around 0.8 ppm and a precision of 0.026 ppm. We also monitor body fat burn based on breath acetone and confirm that breath acetone increases after exercise because it is a volatile byproduct of lipolysis.


Assuntos
Acetona/análise , Testes Respiratórios/métodos , Espectrofotometria Ultravioleta/métodos , Tecido Adiposo/metabolismo , Testes Respiratórios/instrumentação , Desenho de Equipamento , Exercício Físico , Voluntários Saudáveis , Humanos , Monitorização Fisiológica/instrumentação , Monitorização Fisiológica/métodos , Fibras Ópticas , Análise de Regressão , Sensibilidade e Especificidade , Espectrofotometria Ultravioleta/instrumentação , Vácuo , Compostos Orgânicos Voláteis/análise , Adulto Jovem
5.
Phys Med Biol ; 65(17): 175013, 2020 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-32869751

RESUMO

Fiber-coupled scintillation dosimeters are a cost-effective alternative to the conventional ion chambers in radiation dosimetry. However, stem effects from optical fibers such as Cerenkov radiation incur significant errors in the readout signal. Here we introduce a second near-infrared window dosimeter, dubbed as NIR2D, that can potentially be used as real-time radiation detector for clinical megavoltage beams. Lanthanide-based rare-earth NaYF4 nano-phosphors doped with both erbium and cerium elements were synthesized, and a compact 3D printed reader device integrated with a photodetector and data acquisition system was designed. The performance of the NIR2D was tested using a pre-clinical orthovoltage radiation source and a clinical megavoltage radiation source. The system was tested for dose linearity (100, 200, 600 MU), dose rate dependency (100, 200, 400, 600 MU min-1), and energy dependency (6, 10, 15 MV). Test results with the clinical linear accelerator demonstrated excellent dose linearity and dose rate independency when exposed to 6 MV linac beams-both data follows a linear trendline with R2 > 0.99. On the other hand, the NIR2D was energy dependent, where the readout dropped by 9% between 6 and 15 MV. For stem effects, we observed a finite Cerenkov contribution of 1%-3% when exposed between 100-600 MU min-1 (6 MV) and 3%-6% when exposed between 5-15 MV (600 MU min-1). While the stem effects were still observable, we expect that enhancing the current optical setup will simultaneously improve the scintillation signal and reduce the stem effects.


Assuntos
Raios Infravermelhos , Aceleradores de Partículas , Radiometria/instrumentação , Fibras Ópticas
6.
Nat Commun ; 11(1): 4686, 2020 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-32943633

RESUMO

Electrophysiology provides a direct readout of neuronal activity at a temporal precision only limited by the sampling rate. However, interrogating deep brain structures, implanting multiple targets or aiming at unusual angles still poses significant challenges for operators, and errors are only discovered by post-hoc histological reconstruction. Here, we propose a method combining the high-resolution information about bone landmarks provided by micro-CT scanning with the soft tissue contrast of the MRI, which allowed us to precisely localize electrodes and optic fibers in mice in vivo. This enables arbitrating the success of implantation directly after surgery with a precision comparable to gold standard histology. Adjustment of the recording depth with micro-drives or early termination of unsuccessful experiments saves many working hours, and fast 3-dimensional feedback helps surgeons avoid systematic errors. Increased aiming precision enables more precise targeting of small or deep brain nuclei and multiple targeting of specific cortical or hippocampal layers.


Assuntos
Encéfalo/diagnóstico por imagem , Eletrodos Implantados , Processamento de Imagem Assistida por Computador/métodos , Fibras Ópticas , Microtomografia por Raio-X/métodos , Animais , Comportamento Animal , Encéfalo/patologia , Mapeamento Encefálico , Hipocampo/diagnóstico por imagem , Hipocampo/patologia , Hipocampo/cirurgia , Técnicas Histológicas/métodos , Imagem por Ressonância Magnética/métodos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Silício , Técnicas Estereotáxicas
7.
J Vis Exp ; (163)2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32986031

RESUMO

Optogenetic modulation of neuron sub-populations in the brain has allowed researchers to dissect neural circuits in vivo and ex vivo. This provides a premise for determining the role of neuron types within a neural circuit, and their significance in information encoding relative to learning. Likewise, the method can be used to test the physiological significance of two or more connected brain regions in awake and anesthetized animals. The current study demonstrates how VTA glutamate neurons modulate the firing rate of putative pyramidal neurons in the CA1 (hippocampus) of anesthetized mice. This protocol employs adeno-associated virus (AAV)-dependent labeling of VTA glutamate neurons for the tracing of VTA presynaptic glutamate terminals in the layers of the hippocampus. Expression of light-controlled opsin (channelrhodopsin; hChR2) and fluorescence protein (eYFP) harbored by the AAV vector permitted anterograde tracing of VTA glutamate terminals, and photostimulation of VTA glutamate neuron cell bodies (in the VTA). High-impedance acute silicon electrodes were positioned in the CA1 to detect multi-unit and single-unit responses to VTA photostimulation in vivo. The results of this study demonstrate the layer-dependent distribution of presynaptic VTA glutamate terminals in the hippocampus (CA1, CA3, and DG). Also, the photostimulation of VTA glutamate neurons increased the firing and burst rate of putative CA1 pyramidal units in vivo.


Assuntos
Ácido Glutâmico/metabolismo , Hipocampo/fisiologia , Terminações Pré-Sinápticas/fisiologia , Área Tegmentar Ventral/anatomia & histologia , Área Tegmentar Ventral/fisiologia , Potenciais de Ação , Amplificadores Eletrônicos , Animais , Dependovirus/metabolismo , Fluorescência , Imageamento Tridimensional , Masculino , Camundongos Endogâmicos C57BL , Neurônios/fisiologia , Fibras Ópticas , Optogenética
8.
J Biomed Nanotechnol ; 16(5): 715-720, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32919490

RESUMO

Biomedical sensor that sense different molecules with a high refractive index sensitivity is proposed in this work. Plasmonic nanospiral antenna is mounted on a top surface of an optical fiber to reflect the incident optical signal back to the fiber. The reflected signal depends on the nanospiral antenna material, dimensions and the surrounding medium. Using streptavidin molecule, the nanospiral antenna have been simulated based on finite difference time domain method to optimize its dimensions. The optimum dimensions are 10 nm, 55 nm and 40 nm for inner-outer thicknesses and height respectively. The introduced biosensor can detect different molecules based on surface plasmonic resonance, which depends on the shifting of the peak wavelength according to the molecules type. The detected molecules are Streptavidin, Urease, Uricase molecules and Glucose oxidase and Cholesterol oxidase enzymes with a high sensitivity. The maximum refractive index sensitivity is obtained when sensing cholesterol oxidase molecules with 3028 nm/RIU at 3.58 µm peak wavelength. Figure of merit and quality factor are also calculated for all detected molecules. Finally, electric field and optical power, before and after binding, of the reflected signal are illustrated and discussed.


Assuntos
Técnicas Biossensoriais , Desenho de Equipamento , Fibras Ópticas , Refratometria
9.
Artigo em Japonês | MEDLINE | ID: mdl-32814737

RESUMO

In recent years, the exposure dose of the operator's eye lens during interventional radiology operations has become a problem. We therefore evaluated the feasibility of real-time lens dose measurement using scintillator with optical fiber (SOF) dosimeter. Given that the SOF dosimeter is calibrated for direct X-rays, we performed a calibration for scattered X-rays to investigate energy dependence and the accuracy of lens dose measurements. The detection limit was calculated using the Kaiser method. The SOF dosimeter and the radiophotoluminescence glass (RPLG) dosimeter were attached to the protective glasses worn by the operator, and the lens exposure dose of the operator during cardiac catheterization was measured. In the phantom experiment, the SOF dosimeter had an error rate of 5.45% based on the measured value of the ionization chamber dosimeter. The sensitivity characteristics of the SOF dosimeter were slightly reduced on the higher side of the effective energy. The difference in sensitivity was related to variations in the additional filter and energy dependency. The sensitivity difference was 18.5% at maximum. Furthermore, when the additional dose was displayed, the influence of noise on long-term measurement was considerable. Using the Kaiser method to obtain the detection limit, the accuracy of the integrated dose had SOF dosimeter error rates of 4.3% to 15.5% with respect to the integrated value of the RPLG dosimeter when calibrated by the ionization chamber dosimeter. The use of the SOF dosimeter allowed for the real-time visualization of the exposure status of the eye lens and measurements with a relatively high accuracy.


Assuntos
Cristalino , Dosímetros de Radiação , Cateteres Cardíacos , Fibras Ópticas , Imagens de Fantasmas , Radiometria
10.
Water Res ; 184: 116191, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32721764

RESUMO

This paper investigates using UV-C side-emitting optical fibers (SEOFs) to prevent growth of pathogenic bacteria (Pseudomonas aeruginosa and Escherichia coli) on nutrient-rich surfaces. Attaching a SEOF to a single 265 nm light emitting diode (LED) increases irradiation area by >1000x and provides continuous low-irradiance of UV-C light to a large surface area. A zone-of-inhibition protocol was developed to quantify bacterial growth prevention on an agar plate around one SEOF. The inhibition zone increased linearly with irradiance time until achieving a maximum inhibition zone of 2.5 to 3 cm, which received ~ 4.3 mJ/cm2 of 265 nm light in 2 hours. The surviving lawn edge bacterial colonies did not develop UV resistance after two generations of exposure. The agar plate remained bio-available after UV exposure, and bacteria could be grown on pre-illuminated area in the absence of UV-C light. Whereas we previously demonstrated SEOFs can inactivate planktonic bacteria, herein we show the ability of SEOFs to prevent bacteria growth on surfaces. This is the first step towards developing technologies with multiple SEOFs to inhibit biofilm growth on surfaces, which is a ubiquitous challenge across multiple applications from membrane surfaces to surfaces in pipes or water storage systems.


Assuntos
Escherichia coli , Pseudomonas aeruginosa , Biofilmes , Desinfecção , Fibras Ópticas , Raios Ultravioleta
11.
Food Chem ; 332: 127346, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32619938

RESUMO

Fiber optic surface plasmon resonance (SPR) sensor utilizing silver (Ag) and Ag-graphene oxide (GO) is designed and developed for the detection of adulteration of glucose and fructose in pure honey. The concentration range of the two adulterants in pure honey is varied from 4% to 20% with a step change of 4%. The experiments were performed with two different fiber optic probes viz. Probe 1 and Probe 2. Probe 1 is fabricated by coating 50 nm Ag film on unclad optical fiber portion and Probe 2 is fabricated by modifying Ag film with GO for sensitivity improvement. The study confirms that using GO modified fiber optic probe, the sensitivity is enhanced to 24% and 37% for glucose and fructose adulterated honey samples respectively. The technique presented in this study is easy, rapid, label free and shows high prospective for the detection of adulterants in pure honey.


Assuntos
Grafite/química , Mel/análise , Fibras Ópticas , Prata/química , Ressonância de Plasmônio de Superfície/instrumentação
12.
PLoS One ; 15(7): e0235053, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32673337

RESUMO

Study has been made of the thermoluminescence yield of various novel tailor-made silica fibres, 6 and 8 mol % Ge-doped, with four differing outer dimensions, comprised of flat and cylindrical shapes, subjected to electron irradiation. Main thermoluminescence dosimetric characteristics have been investigated, including the glow curve, dose response, energy dependence, minimum detectable dose, effective atomic number, linearity of index and sensitivity of the fibres. The studies have also established the uncertainties involved as well as the stability of response in terms of fading effect, reproducibility and annealing. In addition, dose-rate dependence was accounted for as this has the potential to be a significant factor in radiotherapy applications. The 6 and 8 mol % fibres have been found to provide highly linear dose response within the range 1 to 4 Gy, the smallest size flat fibre, 6 mol% Ge-doped, showing the greatest response by a factor of 1.1 with respect to the highly popular LiF phosphor-based medium TLD100. All of the fibres also showed excellent reproducibility with a standard deviation of < 2% and < 4% for 6 and 8 mol % Ge-doped fibres respectively. For fading evaluation, the smallest 6 mol% Ge-doped dimension flat fibre, i.e., 85 × 270 µm displayed the lowest signal loss within 120 days post-irradiation, at around 26.9% also showing a response superior to that of all of the other fibres. Moreover, all the fibres and TLD-100 chips showed independence with respect to electron irradiation energy and dose-rate. Compared with the 8 mol% Ge-doped optical fibres, the 6 mol% Ge-doped flat optical fibres have been demonstrated to possess more desirable performance features for passive dosimetry, serving as a suitable alternative to TLD-100 for medical irradiation treatment applications.


Assuntos
Germânio , Fibras Ópticas/normas , Dosagem Radioterapêutica , Elétrons , Reprodutibilidade dos Testes , Dióxido de Silício , Dosimetria Termoluminescente/métodos
13.
PLoS One ; 15(5): e0232982, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32407381

RESUMO

A photonic crystal fiber (PCF) structure with a ring-core and 5 well-ordered semiellipse air-holes has been creatively proposed. Through a comparison between the structures with a high refractive index (RI) ring-core and the structure without, it conclude that a PCF with a high RI ring-core can work better. Schott SF57 was elected as the substrate material of ring-core. This paper compares the effects of long-axis and short-axis changes on the PCF and selects the optimal solution. Especially TE0,1 mode's dispersion is maintained between 0 and 3 ps / (nm · km) ranging from 1.45 µm to 1.65 µm. This property can be used to generate a supercontinuum with 200 µm long zero dispersion wavelength (ZDM). In addition, Δneff reaches up to 10-3, which enables the near -degeneracy of the eigenmodes to be almost neglected. The proposed PCF structure will have great application value in the field of optical communications.


Assuntos
Fibras Ópticas , Simulação por Computador , Desenho de Equipamento , Tecnologia de Fibra Óptica/estatística & dados numéricos , Fibras Ópticas/estatística & dados numéricos , Fenômenos Ópticos , Refratometria/estatística & dados numéricos
14.
PLoS One ; 15(5): e0233135, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32442200

RESUMO

PURPOSE: 'Double-firing effect' in which laser firing occurs in the fiber tip and its proximal part is caused by different breakdown rates between fiber jackets and cores. This study investigated a new safe distance concept to prevent scope damage by analyzing the breakdown of the laser fiber jacket and cores. METHODS: Laser fibers were fixed in a benchtop simulation model. The fiber tip was in contact with uniform phantom stones and submerged in saline. Four different energy settings (1.0 or 2.0J x 10Hz or 30Hz) and two different fiber sizes (200 µm and 365 µm) were tested. After three minutes of use at each energy setting, the length of fiber shortening and jacket burn were measured. The fibers were stripped to measure the length of core degradation. RESULTS: Mean degradation lengths were 4.2 to 7.8 mm. There was no statistical difference in the mean lengths of fiber core degradation and jacket burn. However, core degradation was longer than the jacket burn in half of the samples. The mean difference in lengths between core degradation and jacket burn was 0.49 ± 0.90 mm. Lengths of core degradation and the jacket burn were longer at the setting of high-power energy and 200 µm fiber - 2J with 30 Hz. CONCLUSION: To reduce 'double-firing'-induced damage, the authors recommend that laser fiber should be cut 1.0 mm longer than visible jacket burn at high-power settings after 3-min continuous fragmentation. After cutting the fiber, the laser should be checked whether 'double-firing' is no more seen.


Assuntos
Simulação por Computador , Lasers , Modelos Teóricos , Fibras Ópticas
15.
Environ Sci Pollut Res Int ; 27(17): 21281-21291, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32270458

RESUMO

Reduction of mercury emission from coal combustion is a serious task for public health and environmental societies. Herein, Ce-doped TiO2 (Ce/TiO2) catalyst coupling with a novel optical fiber monolith reactor was applied to efficiently remove elemental mercury (Hg0) from coal-fired flue gas. Under the optimal operation condition (i.e., 1.5 mW/cm2 UV light, 90 °C), above 95% of Hg0 removal efficiency was attained over the optical fiber monolith reactor coating with 3.40 g/m2 Ce/TiO2 catalyst. The effects of flue gas compositions on Hg0 removal performance were clarified systematically. Gaseous O2 replenished the surface oxygen, hence maintaining the production of free radicals and promoting the removal of Hg0. SO2, HCl, and NO inhibited Hg0 removal in the absence of O2 due to the competitive adsorption and consumption of free radicals. However, SO2 and HCl significantly enhanced Hg0 removal with the participation of O2, while NO exhibited obviously inhibitory effect even with the assistance of O2. H2O also decreased the Hg0 oxidation capacity owing to the competitive adsorption and reduction of HgO. The optical fiber monolith reactor exhibited much superior Hg0 removal capacity than the powder reactor. Utilization of Ce/TiO2 catalyst coupling with an optical fiber monolith reactor provides a cost-effective method for removing Hg0 from coal-fired flue gas.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Mercúrio , Catálise , Carvão Mineral , Fibras Ópticas , Oxirredução , Centrais Elétricas , Titânio
16.
Opt Express ; 28(2): 970-979, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32121816

RESUMO

A label-free biosensor based on a reflective microfiber probe for in-situ real-time DNA hybridization detection is proposed and experimentally demonstrated. The microfiber probe is simply fabricated by snapping a non-adiabatic biconical microfiber through closing the oxyhydrogen flame during fiber stretching. Assisted with the Fresnel reflection at the end of microfiber, a reflective microfiber modal interferometer is realized. The in-situ DNA hybridization relies on the surface functionalization of a monolayer of Poly-L-lysine (PLL) and synthetic DNA sequences that bind to a given target with high specificity. The detection processes of DNA hybridization in various concentration of target DNA solutions are monitored in real-time and the experimental results present a minimum detectable concentration of 10pM with good repeatability. Additionally, the detection specificity is also investigated by immersing the microfiber probe into the non-complementary ssDNA solutions and observing the spectral variation. The proposed biosensor has advantages of high sensitivity, compact size, ease of use and simple fabrication, which makes it has great potential to be applied in a lot of fields such as disease diagnosis, medicine, and environmental science.


Assuntos
DNA/análise , Hibridização In Situ , Sondas Moleculares/química , Dispositivos Ópticos , Fibras Ópticas , Técnicas Biossensoriais , Tamanho da Partícula , Propriedades de Superfície
17.
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
18.
J Vis Exp ; (157)2020 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-32202517

RESUMO

Random wound coils are a key operational element of most electric apparatus in modern industrial systems, including low voltage electric machines. One of the major current bottlenecks in improved exploitation of electrical devices is the high sensitivity of their wound components to in-service thermal stress. The application of conventional thermal sensing methods (e.g., thermocouples, resistance temperature detectors) for thermal condition monitoring of current carrying random wound coils can impose considerable operational limitations due to sensor size, EMI sensitivity and the existence of electrically conductive material in their construction. Another substantial limitation exists in distributed sensing applications and is caused by what is often a considerable length and volume of conventional sensor wiring leads. This paper reports the design of a fiber optic FBG sensing system intended for enabling real-time distributed internal thermal condition monitoring within random wound coils. The procedure of random wound coil instrumentation with the FBG sensing system is reported in a case study on an IEEE standard wound coil representative of those utilized in electrical machines. The reported work also presents and discusses important practical and technical aspects of FBG sensing system implementation and application, including the FBG array geometry design, sensing head and fiber packaging, the sensor array installation and calibration procedure and the use of a commercial interrogation system for obtaining thermal measurements. Finally, the in situ multiplexed FBG sensing system thermal monitoring performance is demonstrated in representative static and dynamic thermal conditions.


Assuntos
Eletricidade , Fibras Ópticas , Óptica e Fotônica/instrumentação , Calibragem , Desenho de Equipamento , Temperatura
19.
Proc Natl Acad Sci U S A ; 117(12): 6875-6882, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32139609

RESUMO

Pupillometry, a noninvasive measure of arousal, complements human functional MRI (fMRI) to detect periods of variable cognitive processing and identify networks that relate to particular attentional states. Even under anesthesia, pupil dynamics correlate with brain-state fluctuations, and extended dilations mark the transition to more arousable states. However, cross-scale neuronal activation patterns are seldom linked to brain state-dependent pupil dynamics. Here, we complemented resting-state fMRI in rats with cortical calcium recording (GCaMP-mediated) and pupillometry to tackle the linkage between brain-state changes and neural dynamics across different scales. This multimodal platform allowed us to identify a global brain network that covaried with pupil size, which served to generate an index indicative of the brain-state fluctuation during anesthesia. Besides, a specific correlation pattern was detected in the brainstem, at a location consistent with noradrenergic cell group 5 (A5), which appeared to be dependent on the coupling between different frequencies of cortical activity, possibly further indicating particular brain-state dynamics. The multimodal fMRI combining concurrent calcium recordings and pupillometry enables tracking brain state-dependent pupil dynamics and identifying unique cross-scale neuronal dynamic patterns under anesthesia.


Assuntos
Nível de Alerta/fisiologia , Mapeamento Encefálico/métodos , Encéfalo/fisiologia , Cálcio/metabolismo , Imagem por Ressonância Magnética/métodos , Processos Mentais/fisiologia , Pupila/fisiologia , Animais , Processamento de Imagem Assistida por Computador , Fibras Ópticas , Ratos
20.
Cardiovasc Eng Technol ; 11(3): 328-336, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32002814

RESUMO

PURPOSE: Metabolic alterations underlie many pathophysiological conditions, and their understanding is critical for the development of novel therapies. Although the assessment of metabolic changes in vivo has been historically challenging, recent developments in molecular imaging have allowed us to study novel metabolic research concepts directly in the living subject, bringing us closer to patients. However, in many instances, there is need for sensors that are in close proximity to the organ under investigation, for example to study vascular metabolism. METHODS: In this study, we developed and validated a metabolic detection platform directly in the living subject under an inflammatory condition. The signal collected by a scintillating fiber is amplified using a photomultiplier tube and decodified by an in-house tunable analysis platform. For in vivo testing, we based our experiments on the metabolic characteristics of macrophages, cells closely linked to inflammation and avid for glucose and its analog 18F-fluorodeoxyglucose (18F-FDG). The sensor was validated in New Zealand rabbits, in which inflammation was induced by either a) high cholesterol (HC) diet for 16 weeks or b) vascular balloon endothelial denudation followed by HC diet. RESULTS: There was no difference in weight, hemodynamics, blood pressure, or heart rate between the groups. Vascular inflammation was detected by the metabolic sensor (Inflammation: 0.60 ± 0.03 AU vs. control: 0.48 ± 0.03 AU, p = 0.01), even though no significant inflammation/atherosclerosis was detected by intravascular ultrasound, underscoring the high sensitivity of the system. These findings were confirmed by the presence of macrophages on ex vivo aortic tissue staining. CONCLUSION: In this study, we validated a tunable very sensitive metabolic sensor platform that can be used for the detection of vascular metabolism, such as inflammation. This sensor can be used not only for the detection of macrophage activity but, with alternative probes, it could allow the detection of other pathophysiological processes.


Assuntos
Aorta/metabolismo , Aortite/metabolismo , Aterosclerose/metabolismo , Técnicas Biossensoriais , Metabolismo Energético , Fluordesoxiglucose F18/metabolismo , Fibras Ópticas , Compostos Radiofarmacêuticos/metabolismo , Lesões do Sistema Vascular/metabolismo , Animais , Aorta/lesões , Aorta/patologia , Aortite/patologia , Aterosclerose/patologia , Modelos Animais de Doenças , Macrófagos/metabolismo , Macrófagos/patologia , Coelhos , Reprodutibilidade dos Testes , Processamento de Sinais Assistido por Computador , Lesões do Sistema Vascular/patologia
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