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Find video protocols related to scientific articles indexed in Pubmed.
Strategic enhancement of algal biomass, nutrient uptake and lipid through statistical optimization of nutrient supplementation in coupling Scenedesmus obliquus-like microalgae cultivation and municipal wastewater treatment.
Bioresour. Technol.
PUBLISHED: 08-01-2014
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Supplementing proper nutrients could be a strategy for enhancing algal biomass, nutrients uptake and lipid accumulation in the coupling system of biodiesel production and municipal wastewater treatment. However, there is scant information reporting systematic studies on screening and optimization of key supplemented components in the coupling system. The main factors were scientifically screened and optimized using statistical methods. Plackett-Burman design (PBD) was used to explore the roles of added nutrient factors, whereas response surface methodology (RSM) was employed for optimization. Based on the statistic analysis, the optimum added TP and FeCl3·6H2O concentrations for Scenedesmus obliquus-like microalgae growth, nutrients uptake and lipid accumulation were 4.41 mg L(-1) and 6.48 mg L(-1), respectively. The corresponding biomass, lipid content and TN/TP removal efficiency were 1.46 g L(-1), 36.26% and >99%. The predicted value agreed well with the experimental value, as determined by validation experiments, which confirmed the availability and accuracy of the model.
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[Investigation on the psychological quality of mine rescue staff].
Zhonghua Yu Fang Yi Xue Za Zhi
PUBLISHED: 06-28-2014
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To evaluate the psychological quality and its influencing factors of mine rescue staff.
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Achromatic Savart polariscope: choice of materials.
Opt Express
PUBLISHED: 03-26-2014
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This paper presents the achromatization of Savart Polariscope to decrease the lateral-shear dispersion in the lateral displacement. The achromatic Savart Polariscope can be made from two different birefringent crystal materials. The achromatic model for the choices of material is presented. The achievements and performances of different achromatic Savart Polariscopes are demonstrated with numerical simulations and ray tracing program. The chromatic variation in lateral displacement can be reduced by an order of magnitude across the spectral range 0.4?m to 0.9?m.
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Multiple frequency bands of square split resonant rings and metal wire metamaterial.
Appl Opt
PUBLISHED: 10-03-2013
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This work presents experimental measurements of two square split resonant ring and metal wire (SSRR-MW) samples with different cell sizes at microwave frequencies. The geometrical sizes of the metamaterial cells are found to play an important role in the resonant frequency. Cells with different geometrical sizes are chosen to stack into a two-layer or three-layer metamaterial unit to realize the multiple negative passbands. The effective parameters of three separate SSRR-MW models (a one-layer unit, a two-layer unit, and a three-layer unit) are retrieved from the simulation data. The composed models exhibit two or three negative bands by overlapping the passbands of original cells and broadening the overall bandwidth. The recovered parameters show good agreement with the theoretical analysis.
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Modulation depth of static four-phase-divided wind imaging interferometer.
Appl Opt
PUBLISHED: 07-12-2013
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The static four-phase-divided imaging interferometry is a new technology of passive detection for the upper atmospheric wind field. It is featured with real-time detection, no moving parts, stability, and so on. In this paper, its basic theory is discussed, and its characteristics are briefly introduced. Furthermore, its key technical parameter, modulation depth, is analyzed. The relationships of modulation depth with the incident angle and temperature of the working environment are derived by using computer simulation. It is shown that the modulation depth decreases with the increase of the temperature and incident angle. The study provides a theoretical basis to increase the modulation depth of the interferometer, and it is of significance for the development of the upper atmosphere detection technique and theory.
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Complete optical throughput analysis of the static polarization wind imaging interferometer.
Appl Opt
PUBLISHED: 05-15-2013
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The basic principle of the static polarization wind imaging interferometer (SPWII) is expounded in this paper. By using trigonometric function and complex amplitude methods, the complex vibration amplitude of each polarization device with deviation from its ideal direction is calculated. The variations of the fringe visibility and optical throughput with deviation angles are given analytically and simulated numerically. According to the design parameters of the SPWII, the air-equivalent length L is equal to 16.14 cm and the total transmissivity is greater than 0.4. When the polarization directions of each polarization device are all in the ideal directions, the total optical throughput can be maintained at about 16.4% of the incident optical intensity. When the polarization directions of each polarization device are all 2° deviated from the ideal positions, the total optical throughput is decreased by 0.08%. This work would be useful for the realization and data processing of the SPWII.
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Precise spectrum reconstruction of the Fourier transforms imaging spectrometer based on polarization beam splitters.
Opt Lett
PUBLISHED: 04-19-2013
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A method was proposed to precisely reconstruct the spectrum from the interferogram taken by the Fourier transform imaging spectrometer (FTIS) based on the polarization beam splitters. Taken the FTISs based on the Savart polariscope and Wollaston prism as examples, the distorted spectrums were corrected via the proposed method effectively. The feasibility of the method was verified via simulation. The distorted spectrum, recovered from the interferogram taken by the polarization imaging spectrometer developed by us, was corrected.
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Empirical mode decomposition based background removal and de-noising in polarization interference imaging spectrometer.
Opt Express
PUBLISHED: 03-14-2013
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Based on empirical mode decomposition (EMD), the background removal and de-noising procedures of the data taken by polarization interference imaging interferometer (PIIS) are implemented. Through numerical simulation, it is discovered that the data processing methods are effective. The assumption that the noise mostly exists in the first intrinsic mode function is verified, and the parameters in the EMD thresholding de-noising methods is determined. In comparison, the wavelet and windowed Fourier transform based thresholding de-noising methods are introduced. The de-noised results are evaluated by the SNR, spectral resolution and peak value of the de-noised spectrums. All the methods are used to suppress the effect from the Gaussian and Poisson noise. The de-noising efficiency is higher for the spectrum contaminated by Gaussian noise. The interferogram obtained by the PIIS is processed by the proposed methods. Both the interferogram without background and noise free spectrum are obtained effectively. The adaptive and robust EMD based methods are effective to the background removal and de-noising in PIIS.
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Influences of pyramid prism deflection on inversion of wind velocity and temperature in a novel static polarization wind imaging interferometer.
Appl Opt
PUBLISHED: 11-16-2011
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The principle of the novel static polarization wind imaging interferometer (NSPWII) [Acta Opt. Sin. 28, 700 (2008)] based on a pyramid prism is described. Since the measured wind velocity and temperature depend on the transmittance of the pyramid prism, the deflection of the prism introduced by vibration would produce some measuring errors. In this paper, with an assumed deflection case, we analyze its influence on the derived wind velocity and temperature theoretically. The relative error of the inversion temperature and variety of the inversion velocity as they changed with the deflection angle are discussed.
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Influences of the thickness, misalignment, and dispersion of the Savart polariscope on the optical path difference and spectral resolution in the polarization interference imaging spectrometer.
Appl Opt
PUBLISHED: 07-12-2011
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After reviewing the spectrum-dividing principle of the Savart polariscope (SP) in the polarization interference imaging spectrometer (PIIS) that we developed, we analyze the influences of the thickness, misalignment, and dispersion of the SP on the optical path difference (OPD). The theoretical expression of the OPD for the misalignment of the SP optical axis is deduced, and the OPD is analyzed when the incident plane is parallel, at 45°, or orthogonal to the principal section of the left plate of the SP. The selective thickness of the single Savart plate is analyzed when it is placed at the ideal and misalignment positions. The influence of dispersion of the SP on the OPD is analyzed when the misalignment error is ±1. The relationships between the OPD and wavelength are simulated and validated with experiments. This work can provide theoretical and practical guidance for the design, calibration, modulation, innovation, experiment, and engineering of the PIIS.
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The tempo-spatially modulated polarization atmosphere Michelson interferometer.
Opt Express
PUBLISHED: 06-07-2011
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A space-based tempo-spatially modulated polarization atmosphere Michelson interferometer (TSMPAMI) is described. It uses the relative movement between the TSMPAMI and the measured target to change optical path difference. The acquisition method of interferogram is presented. The atmospheric temperatures and horizontal winds can be derived from the optical observations. The measurement errors of the winds and temperatures are discussed through simulations. In the presence of small-scale structures of the atmospheric fields, the errors are found to be significantly influenced by the mismatch of the scenes observed by the adjacent CCD sub-areas aligned along the orbiters track during successive measurements due to the orbital velocity and the exposure time. For most realistic conditions of the orbit and atmosphere, however, the instrument is proven suitable for measuring the atmospheric parameters.
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Cultivation of Chlorella pyrenoidosa in soybean processing wastewater.
Bioresour. Technol.
PUBLISHED: 04-11-2011
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Chlorella pyrenoidosa was cultivated in soybean processing wastewater (SPW) in batch and fed-batch cultures without a supply of additional nutrients. The alga was able to remove 77.8 ± 5.7%, 88.8 ± 1.0%, 89.1 ± 0.6% and 70.3 ± 11.4% of soluble chemical oxygen demand (SCOD(Cr)), total nitrogen (TN), NH(4)(+)-N and total phosphate (TP), respectively, after 120 h in fed-batch culture. C. pyrenoidosa attained an average biomass productivity of 0.64 g L(-1)d(-1), an average lipid content of 37.00 ± 9.34%, and a high lipid productivity of 0.40 g L(-1)d(-1). Therefore, cultivation of C. pyrenoidosa in SPW could yield cleaner water and useful biomass.
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Analysis of the resonant frequency of the octagonal split resonant rings with metal wires.
Appl Opt
PUBLISHED: 10-12-2010
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The resonant frequency determined by octagonal split resonant rings (SRRs) is presented and analyzed. The simulated results show that the resonant frequency improves when the opening size of the SRRs becomes larger, and that enhancement of the coupling degree can improve the resonant frequency and widen the band. Four samples are designed to implement the experimental measurement. The results show that the bandwidth of the resonant frequency becomes wider when the thickness of the substrate becomes thinner, and the resonant frequency is shifted by changing the cell size. It is demonstrated that the experimental results show good agreement with the theoretical analysis.
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The data processing of the temporarily and spatially mixed modulated polarization interference imaging spectrometer.
Opt Express
PUBLISHED: 04-15-2010
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Based on the basic imaging theory of the temporally and spatially mixed modulated polarization interference imaging spectrometer (TSMPIIS), a method of interferogram obtaining and processing under polychromatic light is presented. Especially, instead of traditional Fourier transform spectroscopy, according to the unique imaging theory and OPD variation of TSMPIIS, the spectrum is reconstructed respectively by wavelength. In addition, the originally experimental interferogram obtained by TSMPIIS is processed in this new way, the satisfying result of interference data and reconstructed spectrum prove that the method is very precise and feasible, which will great improve the performance of TSMPIIS.
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Wide-spectrum reconstruction method for a birefringence interference imaging spectrometer.
Opt Lett
PUBLISHED: 02-04-2010
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We present a mathematical method used to determine the spectrum detected by a birefringence interference imaging spectrometer (BIIS). The reconstructed spectrum has good precision over a wide spectral range, 0.4-1.0 microm. This method considers the light intensity as a function of wavelength and avoids the fatal error caused by birefringence effect in the conventional Fourier transform method. The experimental interferogram of the BIIS is processed in this new way, and the interference data and reconstructed spectrum are in good agreement, proving this method to be very exact and useful. Application of this method will greatly improve the instrument performance.
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Miniature periodic structures of left-handed materials.
Appl Opt
PUBLISHED: 01-22-2010
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Based on the analysis of rectangular periodic structures, the resonance frequency band is found to be shifted and broadened from low frequency to high frequency by adjustment of the corresponding structure size. Computer simulation shows that a miniature split-ring resonator can enhance and broaden resonance frequency without changing the stop-band location. According to the theoretical parameters, different experimental samples can be fabricated. The experimental results are generally the same as those predicted theoretically. A comparison of the experimental and theoretical results concluded that a miniature periodic structure broadened the frequency of the stop band and enhanced the resonance frequency, which are important for the study of left-handed materials.
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Principle and analysis of a polarization imaging spectrometer.
Appl Opt
PUBLISHED: 04-22-2009
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A polarization imaging spectrometer based on a modified Savart polariscope with a moving wedge prism is presented. The principle of the instrument is described, and the optical path difference as a function of the moving wedge prisms moving displacement is calculated and analyzed. It employs a common-path configuration and is not sensitive to the nonuniform variation of moving speed and environmental vibrations. In comparison with the polarization imaging spectrometer based on the Savart polariscope, this spectrometer is a framing instrument rather than a pushbrooming device. Only the transmission of birefringent materials and detector sensitivity limit the available spectral range of such an instrument.
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Static hyperspectral imaging polarimeter for full linear Stokes parameters.
Opt Express
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A compact, static hyperspectral imaging linear polarimeter (HILP) based on a Savart interferometer (SI) is conceptually described. It improves the existing SI by replacing front polarizer with two Wollaston prisms, and can simultaneously acquire four interferograms corresponding to four linearly polarized lights on a single CCD. The spectral dependence of linear Stokes parameters can be recovered with Fourier transformation. Since there is no rotating or moving parts, the system is relatively robust. The interference model of the HILP is proved. The performance of the system is demonstrated through a numerical simulation, and the methods for compensating the imperfection of the polarization elements are described.
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Influence of the tilting reflection mirror on the temperature and wind velocity retrieved by a polarizing atmospheric Michelson interferometer.
Appl Opt
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The principles of a polarizing atmospheric Michelson interferometer are outlined. The tilt of its reflection mirror results in deflection of the reflected beam and affects the intensities of the observed inteferogram. This effect is systematically analyzed. Both rectangular and circular apertures are considered. The theoretical expression of the modulation depth and phase of the interferogram are derived. These parameters vary with the inclination angle of the mirror and the distance between the deflection center and the optical axis and significantly influence the retrieved temperature and wind speed. If the wind and temperature errors are required to be less than 3 m/s and 5 K, the deflection angle must be less than 0.5°. The errors are also dependent on the shape of aperture. If the reflection mirror is deflected in one direction, the temperature error is smaller for a circular aperture (1.3 K) than for a rectangular one (2.6 K), but the wind velocity errors are almost the same (less than 3 m/s). If the deflection center and incident light beam are coincident, the temperature errors are 3 × 10(-4) K and 0.45 K for circular and rectangular apertures, respectively. The wind velocity errors are 1.2 × 10(-3) m/s and 0.06 m/s. Both are small. The result would be helpful for theoretical research and development of the static polarization wind imaging interferometer.
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Static polarization-difference interference imaging spectrometer.
Opt Lett
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A static polarization-difference imaging spectrometer is conceptually described and demonstrated through experiment. It consists of a Wollaston prism, a Savart polariscope, a linear analyzer, and a CCD camera. This design improves the existing polarization-difference system by eliminating its moving parts and obtaining the spectral variation of the polarization state, and making the system more compact and robust. After simultaneously acquiring two sequential interference images corresponding to two orthogonal polarization states, the hyperspectral images of the states can be reconstructed, respectively. The use of uniaxial birefringent crystal can widen the detectable spectral region.
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Snapshot imaging polarimeter using modified Savart polariscopes.
Appl Opt
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In this paper, based on the combination of two modified Savart polariscopes, we present a snapshot imaging polarimeter and show that the carrier frequency is two times higher than that of the snapshot imaging polarimeter using two conventional Savart polariscopes. The signal-to-noise ratio and the spatial resolution of imagery in each channel are improved due to the increase of the carrier frequency when we filter the channels to recover the Stokes vector images. Moreover, compared with conventional imaging polarimetry, the remarkable advantage of the proposed instrument is that it is also simple, compact, miniature, snapshotted, and static (no moving parts). To demonstrate the feasibility of the proposed snapshot imaging polarimeter, the numerical simulation of a design example is presented in detail.
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The effect of bacterial contamination on the heterotrophic cultivation of Chlorella pyrenoidosa in wastewater from the production of soybean products.
Water Res.
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This study examined the impacts of bacteria on the algal biomass, lipid content and efficiency of wastewater treatment during the heterotrophic cultivation of Chlorella pyrenoidosa. Our results showed that soybean-processing wastewater can enhance the accumulation of lipids in algal cells and thus raise the lipid yield in the pure culture. The bacteria coexisting with algae improved the degradation of total nitrogen (TN), total phosphorus (TP), glucose and chemical oxygen demand (COD). Although the biomass productivity of algae was not significantly affected, the total algal lipid content and lipid production rate were slightly reduced when bacteria coexisted with algae. The difference in the compositions of the medium is presumed to be the main contributing factor for the variation in total lipid content in presence and absence of bacteria. The TN, TP, and COD decreased during the assimilatory process undertaken by C. pyrenoidosa, and the removal efficiency of TN by bacteria depended on the type of nitrogen species in the medium. Additionally, the apparent interaction between the bacterial and algal cultures varied with the changes in experimental conditions. Algae could compete with bacteria for the carbon and energy sources, and inhibit the growth of the bacteria in the presence of high organic matter concentration in the medium.
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Spectrum reconstruction based on the constrained optimal linear inverse methods.
Opt Lett
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The dispersion effect of birefringent material results in spectrally varying Nyquist frequency for the Fourier transform spectrometer based on birefringent prism. Correct spectral information cannot be retrieved from the observed interferogram if the dispersion effect is not appropriately compensated. Some methods, such as nonuniform fast Fourier transforms and compensation method, were proposed to reconstruct the spectrum. In this Letter, an alternative constrained spectrum reconstruction method is suggested for the stationary polarization interference imaging spectrometer (SPIIS) based on the Savart polariscope. In the theoretical model of the interferogram, the noise and the total measurement error are included, and the spectrum reconstruction is performed by using the constrained optimal linear inverse methods. From numerical simulation, it is found that the proposed method is much more effective and robust than the nonconstrained spectrum reconstruction method proposed by Jian, and provides a useful spectrum reconstruction approach for the SPIIS.
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Effect and suppression of secondary fringes in FATWindII.
Appl Opt
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By considering the instrument as a complex operator on the incident electric field, a model to calculate secondary fringes of the Field-widened, Achromatic, Temperature-compensated Wind Imaging Interferometer (FATWindII) has been built. The distribution of secondary fringes on a charge coupled device detector has been plotted. The effects of secondary fringes on inversion errors of temperature and wind velocity have been presented. The results show that antireflection coating on the air/glass interface cannot meet the accuracy requirement of FATWindII. A theoretical method for calculating the optimal wedge angles of compensating glasses is derived to suppress the secondary fringes while preserving the primary ones. By adopting both methods, coating with antireflection film and shaping wedge compensating glasses, the relative intensity of secondary fringes is reduced to below 2.5% and the inversion errors of temperature and wind velocity introduced by the effects of secondary fringes can be minimized to about 0.05 K and 0.045 ms(-1), respectively.
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Optical throughput of the Sagnac interferometer with a modified large optical path difference.
Appl Opt
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The basic principle of Sagnac interferometer with modified large optical path difference is expounded on in this paper. According to the Fresnel formula, electromagnetic field energy, and energy flux, the transmittance and reflectance of each interface of a Sagnac interferometer are calculated, respectively, and then the exact expressions of the optical throughput changing with the incident angle, the angle of the incident plane, and paper plane (the bottom plane of Sagnac interferometer) and Sagnac interferometer acute angles are given. Furthermore, we analyze the effects of various parameters on the optical throughput by computer simulation, and some important conclusions are obtained. This work is of great scientific significance to the static, real-time simultaneous detection of upper atmospheric wind field.
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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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