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Find video protocols related to scientific articles indexed in Pubmed.
Kinetics of polarization gratings assisted with polarized violet light in bacteriorhodopsin films.
J Opt Soc Am A Opt Image Sci Vis
PUBLISHED: 12-11-2013
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Polarization gratings can be recorded in bacteriorhodopsin films by an orthogonal pair of linearly or circularly polarized beams. If a linearly polarized auxiliary violet light is added during the grating formation, the grating becomes polarization-sensitive. A theoretical model based on the two-state photochromic theory is proposed to calculate the diffraction efficiency kinetics of these polarization gratings. In both cases, the additional linearly polarized auxiliary violet irradiation improves the steady-state diffraction efficiency and leads to a cosine modulation of the steady-state diffraction efficiency by the polarization orientation of the readout beam. Experiment results demonstrate the correctness of the theoretical model.
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Time-resolved photoluminescence of silicon microstructures fabricated by femtosecond laser in air.
Opt Express
PUBLISHED: 10-10-2013
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Green photoluminescence (PL) from silicon microstructures fabricated by femtosecond laser in air was studied at different temperature by time-resolved spectroscopy. The PL decay profiles are well fitted by a stretched exponential function: I(t)=I(0)*exp[-(t/?)?]. The dependence of the decay time constant ? and of the stretching index ? on PL photon energy and on the temperature is investigated. A model of transport and recombination of the carriers is introduced as a possible explanation of the stretched exponential decay. The nonradiative recombination rate of the localized carriers, which is dependent on the carrier density and influenced by the trapping site density and the temperature, is deduced to be responsible for this kind of decay.
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Fast UV-Vis photorefractive response of Zr and Mg codoped LiNbO3:Mo.
Opt Express
PUBLISHED: 05-15-2013
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A series of LN:Mo,Zr and LN:Mo,Mg crystals with different doping concentrations were grown and their holographic properties were investigated from UV to the visible range. Each crystal allows for holographic storage from UV to the visible as LN:Mo. When the concentration of MgO is enhanced to 6.5 mol%, the response time can be dramatically shortened to 0.22 s, 0.33 s, 0.37 s and 1.2 s for 351, 488, 532, and 671 nm laser, respectively. The results show that LN:Mo,Mg is a promising candidate for all-color holographic volume storage with fast response.
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Shifting the spherical focus of a 4Pi focusing system.
Opt Express
PUBLISHED: 01-26-2011
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In a 4Pi focusing system radially polarized laser beams can be focused to a spherical focal spot. For many applications, e.g., for moving trapped particles or for scanning a specimen, one would like to change the position of focal spot along the optical axis without moving lenses or laser beams. We demonstrate how this can be achieved by modulating the phase of the input field at the pupil plane of the lens. The required phase modulation function is determined by spherical wave expansion of the plane wave factors in the Richards-Wolf integral.
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High resistance against ultraviolet photorefraction in zirconium-doped lithium niobate crystals.
Opt Lett
PUBLISHED: 07-29-2010
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The UV photorefraction of Zr-doped lithium niobate (LN:Zr) was investigated. The experimental results show that LN:Zr crystals have high resistance against photorefraction in the UV region as well as in the visible range and can withstand a UV light intensity of above 10(5) W/cm(2). According to the fitting results of erasing curves with UV and green light, a two-center O(2-/-)-defect model was suggested. Our results indicate that LN:Zr is an excellent candidate for optical damage resistance from the UV to the visible spectrum.
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Nonlinear spectrum broadening of femtosecond laser pulses in photorefractive waveguide arrays.
Opt Express
PUBLISHED: 07-01-2010
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In photorefractive waveguide arrays, the process and extent of spectral broadening of femtosecond laser pulse caused by self-phase modulation are studied theoretically and experimentally. The threshold of self-phase modulation is more than two times larger than the common threshold in a bulk sample, which affects the extent of spectral broadening dramatically. The coupling length and the ratio between the common threshold and the input peak intensity of the femtosecond laser pulse are the two key parameters dominating these phenomena. The experimental results confirm the theoretical expectation.
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Light-controllable coherent backscattering from water suspension of lithium niobate microcrystalline particles.
Opt Lett
PUBLISHED: 06-03-2010
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We experimentally study coherent backscattering of light for a water suspension of lithium niobate microcrystalline particles. Light-controllable weak localization of photons in a suspension is demonstrated for the first time to our knowledge. The effect is attributed to the reorientation of microcrystalline particles in the field of a linearly polarized pump beam. Thus the isotropic suspension becomes partially anisotropic.
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Ultraviolet irradiation induces autofluorescence enhancement via production of reactive oxygen species and photodecomposition in erythrocytes.
Biochem. Biophys. Res. Commun.
PUBLISHED: 05-03-2010
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Ultraviolet (UV) light has a significant influence on human health. In this study, human erythrocytes were exposed to UV light to investigate the effects of UV irradiation (UVI) on autofluorescence. Our results showed that high-dose continuous UVI enhanced erythrocyte autofluorescence, whereas low-dose pulsed UVI alone did not have this effect. Further, we found that H(2)O(2), one type of reactive oxygen species (ROS), accelerated autofluorescence enhancement under both continuous and pulsed UVI. In contrast, continuous and pulsed visible light did not result in erythrocyte autofluorescence enhancement in the presence or absence of H(2)O(2). Moreover, NAD(P)H had little effect on UVI-induced autofluorescence enhancement. From these studies, we conclude that UVI-induced erythrocyte autofluorescence enhancement via both UVI-dependent ROS production and photodecomposition. Finally, we present a theoretical study of this autofluorescence enhancement using a rate equation model. Notably, the results of this theoretical simulation agree well with the experimental data further supporting our conclusion that UVI plays two roles in the autofluorescence enhancement process.
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Improved sensitivity of nonvolatile holographic storage in triply doped LiNbO(3):Zr,Cu,Ce.
Opt Express
PUBLISHED: 04-15-2010
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We have designed and grown triply doped LiNbO(3):Zr,Cu,Ce crystal and investigated its characteristics of nonvolatile holographic storage. Its observed that the photorefractive sensitivity of LiNbO(3):Zr,Cu,Ce has improved to 0.099 cm/J, which is about one order of magnitude larger than that of congruent LiNbO(3):Cu,Ce. And LiNbO(3):Zr,Cu,Ce also has high suppression to light-induced scattering. Our results indicated that triply doped LiNbO(3):Zr,Cu,Ce is an excellent candidate for nonvolatile holographic data storage.
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Increased optical-damage resistance in tin-doped lithium niobate.
Opt Lett
PUBLISHED: 03-19-2010
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Applications of lithium niobate in nonlinear optics at high light intensities are seriously hampered by optical damage. Recent investigations have shown that Hf(4+) and Zr(4+) ions have some advantages in suppressing optical damage of LiNbO(3) with respect to Mg(2+). Here we present Sn-doped LiNbO(3) (Sn:LN). Experimental results indicate that Sn:LN has similar optical damage resistance to Mg-doped LiNbO(3), but the doping threshold of Sn is only 2.5 mol.%, where its distribution coefficient is 0.98. Hence Sn(4+) ion turns out to be another good choice for increasing optical damage resistance of LiNbO(3).
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Fast responsive nonvolatile holographic storage in LiNbO(3) triply doped with Zr, Fe, and Mn.
Opt Lett
PUBLISHED: 12-18-2009
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Iron and manganese doubly doped LiNbO(3) (LN:Fe,Mn) has been suggested for nonvolatile photorefractive recording; however, its response time is still of the order of minutes. Here we present results on LiNbO(3) triply doped with zirconium, iron, and manganese (LN:Zr,Fe,Mn). The codoping with Zr eliminates undesirable intrinsic traps, which strongly enhances the charge transition speed. The response time of LN:Zr,Fe,Mn for nonvolatile holographic storage shortens to only 0.95 s (wavelength of 532 nm and intensity of 400 mW/cm(2)), and the sensitivity reaches 1.31 cm/J. Thus it seems that we have found an excellent recording medium for practical holographic storage devices.
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Optical trapping and manipulation of metallic micro/nanoparticles via photorefractive crystals.
Opt Express
PUBLISHED: 06-10-2009
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A simple method to trap and manipulate metallic micro/nano-particles on the surface of photorefractive crystals is proposed. After inducing inhomogeneous charge density and space-charge fields in photorefractive crystals by non-uniform illumination, both uncharged and charged metallic particles can be trapped on the illuminated surface due to dielectrophoretic force and electrophoretic force, respectively. A transition from dielectrophoresis to electrophoresis is observed when manipulating nano-silver particles with high surface space-charge field. Our results show that this method is simple and effective to form surface microstructures of metallic particles.
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Real-time imaging of autofluorescence NAD(P)H in single human neutrophils.
Appl Opt
PUBLISHED: 02-20-2009
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Real-time detection of NAD(P)H is particularly important for understanding physiological activities of neutrophils. We scrutinize the performance of weak light detection systems with electron multiplying CCDs (EMCCDs) with regard to the feasibility of valid investigations by autofluorescence NAD(P)H in single human neutrophils. The low-noise amplification facility of EMCCDs is indeed just adequate to permit detection at an irradiation level where neither quenching nor phototoxic effects occur. For demonstration, a neutrophil respiratory burst was triggered and observed in real time. Our low-intensity detection system fulfills all requirements for real-time investigations at high spatiotemporal resolution in the field of neutrophil physiology and pathology.
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Ultraviolet irradiation-dependent fluorescence enhancement of hemoglobin catalyzed by reactive oxygen species.
PLoS ONE
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Ultraviolet (UV) light has a potent effect on biological organisms. Hemoglobin, an oxygen-transport protein, plays an irreplaceable role in sustaining life of all vertebrates. In this study we scrutinize the effects of ultraviolet irradiation (UVI) as well as visible irradiation on the fluorescence characteristics of bovine hemoglobin (BHb) in vitro. Data show that UVI results in fluorescence enhancement of BHb in a dose-dependent manner. Furthermore, UVI-induced fluorescence enhancement is significantly increased when BHb is pretreated with hydrogen peroxide (H(2)O(2)), a type of reactive oxygen species (ROS). Meanwhile, The water-soluble antioxidant vitamin C suppresses this UVI-induced fluorescence enhancement. In contrast, green light irradiation does not lead to fluorescence enhancement of BHb no matter whether H(2)O(2) is acting on the BHb solution or not. Taken together, these results indicate that catalysis of ROS and UVI-dependent irradiation play two key roles in the process of UVI-induced fluorescence enhancement of BHb.
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Fast photorefractive response of vanadium-doped lithium niobate in the visible region.
Opt Lett
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A series of vanadium-doped lithium niobate crystals was grown and their photorefractive properties were investigated with a 532 nm laser. At a total light intensity of 471 mW/cm(2), a short response time of only 0.57 s was achieved for 0.1 mol.% vanadium in LiNbO(3). The photorefractive process is dominated by the diffusion field instead of the photovoltaic field. The dominant charge carriers are electrons. The possible mechanism for the fast photorefractive response is discussed.
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Autofocusing based on wavelength dependence of diffraction in two-wavelength digital holographic microscopy.
Opt Lett
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An autofocusing method for two-wavelength digital holographic microscopy (TWDHM) based on the wavelength dependence of the diffraction process is proposed. Red and green lights are employed for the illumination of the TWDHM, and the generated holograms are recorded simultaneously by a color CCD camera. Due to the wavelength dependency of the diffraction process, the farther the reconstruction plane is from the image plane, the larger the difference is between the red and green light distributions. Thus, the image plane can be determined by finding the minimum of the variation between the red and green lights on their amplitude distributions. The feasibility of the proposed method is demonstrated by simulation and experiment.
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Optical refocusing three-dimensional wide-field fluorescence lifetime imaging microscopy.
Opt Express
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Three-dimensional fluorescence lifetime microscopy is achieved by combining wide-field fluorescence lifetime imaging with a remote optical refocusing method. As required for some applications in dynamic research for physics, chemistry, or biology, it is thereby not necessary to move the sample, i.e., the specimen is not disturbed during measurement. Using a fluorescent microsphere the performance of the system has been tested successfully with respect to three-dimensional fluorescence lifetime microscopy as well as time-resolved fluorescence spectroscopy.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.