The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform

Qiyun Zhou - One of the best experts on this subject based on the ideXlab platform.

  • effects of carbon black content on microwave absorbing and mechanical properties of linear low density polyethylene ethylene octene copolymer calcium carbonate composites
    Polymer-plastics Technology and Engineering, 2011
    Co-Authors: Qincai Ling, Jianzhong Sun, Qian Zhao, Qiyun Zhou
    Abstract:

    Calcium carbonate (CC) and carbon black (CB) filled composites based on linear low density polyethylene (LLDPE) and ethylene-octene copolymer (POE) were prepared by means of melt blending. The microwave absorbing performances were measured using the arch Method and the electromagnetic parameters of composites were determined by transmission/Reflection Method. The structure and surface morphology were observed using transmission electron microscopy (TEM). LLDPE/POE/CC/CB composites show excellent microwave absorption ability. The dielectric loss from the filler CB is responsible for the microwave absorption of polymer composites. CB can effectively improve the mechanical properties of LLDPE/POE/CC composites.

  • microwave absorbing properties of linear low density polyethylene ethylene octene copolymer composites filled with short carbon fiber
    Materials Science and Engineering B-advanced Functional Solid-state Materials, 2009
    Co-Authors: Qincai Ling, Jianzhong Sun, Qian Zhao, Qiyun Zhou
    Abstract:

    Abstract Linear low density polyethylene/ethylene–octene copolymer composites filled with short carbon fiber were prepared by melt blending. The structure and surface morphology of the samples were characterized by scanning electron microscopy and transmission electron microscopy. The electromagnetic parameters were determined with transmission/Reflection Method in the range of 2.6–17.8 GHz, and microwave absorbing properties of the composites were determined using the arch Method in the frequency range of 2.0–18.0 GHz. The experimental results show that short carbon fiber loading influences the absorbing peak position and Reflection loss, and that the composites containing 30 wt.% short carbon fiber display two absorbing peaks. The maximum Reflection losses achieve −15.66 dB at 4.6 GHz and −17.37 dB at 16.4 GHz. The bandwidth corresponding to the Reflection loss below −10 dB amounts to about 3.6 GHz. The contribution for the microwave absorption comes from the dielectric loss. The theoretical calculation results of Reflection loss are in agreement with the experimental results using the transmission line theory.

Jianguo Tian - One of the best experts on this subject based on the ideXlab platform.

  • continuous refractive index dispersion measurement based on derivative total Reflection Method
    Review of Scientific Instruments, 2015
    Co-Authors: Zhichao Deng, Jin Wang, Wenyuan Zhou, Chunping Zhang, Qing Ye, Jianguo Tian
    Abstract:

    Traditionally, continuous refractive index dispersion (CRID) measurement of materials with scattering is hard to realize. In this paper, CRID measurement based on the derivative total Reflection Method (CRIDM-DTRM) is proposed to measure the CRID of both absorption and scattering materials. It effectively determined the CRID of K9 glass, concentrated milk, and 0.5% methyl red solution in the 400-750 nm range with the spectral resolution of about 0.259 nm. For the first time, CRID of a scattering material is measured. CRIDM-DTRM is a useful technique in the field of RID measurement, especially for biotissues and anomalous dispersion materials.

  • study on the refractive index matching effect of ultrasound on optical clearing of bio tissues based on the derivative total Reflection Method
    Biomedical Optics Express, 2014
    Co-Authors: Huanhuan Zeng, Jin Wang, Zhichao Deng, Wenyuan Zhou, Chunping Zhang, Qing Ye, Jianguo Tian
    Abstract:

    In recent years, the tissue optical clearing (OC) technique in the biomedicine field has drawn lots of attention. Various physical and chemical Methods have been introduced to improve the efficacy of OC. In this study, the effect of the combination of glycerol and ultrasound treatment on OC of in vitro porcine muscle tissues has been investigated. The refractive index (RI) matching mechanism of OC was directly observed based on the derivative total Reflection Method. A theoretical model was used to simulate the proportion of tissue fluid in the illuminated area. Moreover, the total transmittance spectra have been obtained by a spectrometer over the range from 450 nm to 700 nm. The administration of glycerol and ultrasound has led to an increase of the RI of background medium and a more RI matching environment was achieved. The experimental results support the validity of the ultrasound treatment for OC. The RI matching mechanism has been firstly quantitatively analyzed based on the derivative total Reflection Method.

  • study of dynamic pressure induced refractive index change using derivative total Reflection Method
    Journal of Biomedical Optics, 2013
    Co-Authors: Jin Wang, Zhichao Deng, Tengqian Sun, Wenyuan Zhou, Jianchun Mei, Chunping Zhang, Jianguo Tian
    Abstract:

    We report the dynamic refractive index (RI) change of tissue under a stepped compression load using a custom-built pressure apparatus. Angle-dependent reflectance profiles of biotissue samples are recorded, and the RI values are resolved using the derivative total Reflection Method. These results are relevant for understanding the mechanism of mechanical optical clearing, for investigating tissue dynamics under mechanical stimuli, and for other biomedical applications.

Qincai Ling - One of the best experts on this subject based on the ideXlab platform.

  • effects of carbon black content on microwave absorbing and mechanical properties of linear low density polyethylene ethylene octene copolymer calcium carbonate composites
    Polymer-plastics Technology and Engineering, 2011
    Co-Authors: Qincai Ling, Jianzhong Sun, Qian Zhao, Qiyun Zhou
    Abstract:

    Calcium carbonate (CC) and carbon black (CB) filled composites based on linear low density polyethylene (LLDPE) and ethylene-octene copolymer (POE) were prepared by means of melt blending. The microwave absorbing performances were measured using the arch Method and the electromagnetic parameters of composites were determined by transmission/Reflection Method. The structure and surface morphology were observed using transmission electron microscopy (TEM). LLDPE/POE/CC/CB composites show excellent microwave absorption ability. The dielectric loss from the filler CB is responsible for the microwave absorption of polymer composites. CB can effectively improve the mechanical properties of LLDPE/POE/CC composites.

  • microwave absorbing properties of linear low density polyethylene ethylene octene copolymer composites filled with short carbon fiber
    Materials Science and Engineering B-advanced Functional Solid-state Materials, 2009
    Co-Authors: Qincai Ling, Jianzhong Sun, Qian Zhao, Qiyun Zhou
    Abstract:

    Abstract Linear low density polyethylene/ethylene–octene copolymer composites filled with short carbon fiber were prepared by melt blending. The structure and surface morphology of the samples were characterized by scanning electron microscopy and transmission electron microscopy. The electromagnetic parameters were determined with transmission/Reflection Method in the range of 2.6–17.8 GHz, and microwave absorbing properties of the composites were determined using the arch Method in the frequency range of 2.0–18.0 GHz. The experimental results show that short carbon fiber loading influences the absorbing peak position and Reflection loss, and that the composites containing 30 wt.% short carbon fiber display two absorbing peaks. The maximum Reflection losses achieve −15.66 dB at 4.6 GHz and −17.37 dB at 16.4 GHz. The bandwidth corresponding to the Reflection loss below −10 dB amounts to about 3.6 GHz. The contribution for the microwave absorption comes from the dielectric loss. The theoretical calculation results of Reflection loss are in agreement with the experimental results using the transmission line theory.

Kiyotaka Fukumoto - One of the best experts on this subject based on the ideXlab platform.

  • head free remote gaze detection system based on pupil corneal Reflection Method with using two video cameras one point and nonlinear calibrations
    International Conference on Human-Computer Interaction, 2013
    Co-Authors: Yoshinobu Ebisawa, Kiyotaka Fukumoto
    Abstract:

    We developed a pupil-corneal Reflection Method-based gaze detection system, which allows head movements and achieves easy gaze calibration. The proposed gaze detection theory determines gaze points on a PC screen from the vector from the corneal Reflection to pupil center, 3D pupil position, two cameras position, etc. In a gaze calibration procedure, after a user is asked to gaze one specific calibration target at a center of a PC screen, the nonlinear characteristic of the eyes has been automatically corrected while the user is using this gaze system. The experimental results show that the proposed calibration Method improved the precision of gaze detection during browsing web pages. In addition, the average gaze error in the visual angle is less than 0.6 degree for the nine head positions.

  • head free remote eye gaze detection system based on pupil corneal Reflection Method with easy calibration using two stereo calibrated video cameras
    IEEE Transactions on Biomedical Engineering, 2013
    Co-Authors: Yoshinobu Ebisawa, Kiyotaka Fukumoto
    Abstract:

    We have developed a pupil-corneal Reflection Method-based gaze detection system, which allows large head movements and achieves easy gaze calibration. This system contains two optical systems consisting of components such as a camera and a near-infrared light source attached to the camera. The light source has two concentric LED rings with different wavelengths. The inner and outer rings generate bright and dark pupil images, respectively. The pupils are detected from a difference image created by subtracting the bright and dark pupil images. The light source also generates the corneal Reflection. The 3-D coordinates of the pupils are determined by the stereo matching Method using two optical systems. The vector from the corneal Reflection center to the pupil center in the camera image is determined as r. The angle between the line of sight and the line passing through the pupil center and the camera (light source) is denoted as θ. The relationship θ = k | \bm r | is assumed, where k is a constant. The theory implies that head movement of the user is allowed and facilitates the gaze calibration procedure. In the automatic calibration Method, k is automatically determined while the user looks around on the PC screen without fixating on any specific calibration target. In the one-point calibration Method, the user is asked to fixate on one calibration target at the PC screen in order to correct the difference between the optical and visual axes. In the two-point calibration Method, in order to correct the nonlinear relationship between θ and | r |, the user is asked to fixate on two targets. The experimental results show that the three proposed calibration Methods improve the precision of gaze detection step by step. In addition, the average gaze error in the visual angle is less than 1° for the seven head positions of the user.

Jens Dawczynski - One of the best experts on this subject based on the ideXlab platform.

  • macular pigment optical density measurements by one wavelength Reflection photometry influence of cataract surgery on the measurement results
    Graefes Archive for Clinical and Experimental Ophthalmology, 2014
    Co-Authors: Bogdana Komar, Franziska G Rauscher, Renate Wiedemann, Jens Dawczynski
    Abstract:

    The main objective of the present study was the investigation of possible influence of lens opacification on macular pigment optical density (MPOD) measurements. Eighty-six eyes of 64 patients (mean age 73.4 ± 8.3 years) were included in the study. MPOD was prospectively measured using the one-wavelength Reflection Method (Visucam500, Carl Zeiss Meditec AG) before and after cataract extraction, with implantation of a blue-light filtering intraocular lens (AlconSN60WF). The median of the maximum optical density (MaxOD) and the median of the mean optical density (MeanOD) measurements of macular pigment across the subject group were evaluated. Statistically significant differences were noticed between pre-operative and post-operative measurements, the absolute values were generally lower after cataract extraction. The following median (lower/upper quartile) differences across the group were determined: MaxOD −33.8 % (−46.2 to −19.1 %), MeanOD −44.0 % (−54.6 to −26.6 %). Larger changes were observed in elderly patients [<70 years of age (n = 25 eyes): MaxOD −13.4 % (−20.5 to 3.6 %), MeanOD −23.6 % (−30.5 to −15.3 %) versus patients ≥70 years (n = 61 eyes) MaxOD −40.5 % (−53.2 to −30.1 %), MeanOD −47.2 % (−57.8 to −40.1 %)] and in patients with progressed stage of cataract. MaxOD for lens opacification grade 1 (n = 9 eyes): −27.4 % (−42.1 to −19.6 %), grade 2 (n = 26 eyes): −35.0 % (−44.2 to −25.3 %), grade 3 (n = 21 eyes): −34.4 % (−45.4 to −11.4 %), grade 4 (n = 25 eyes): −32.6 % (−53.2 to −6.4 %), and grade 5 (n = 5 eyes): −53.5 % (−61.7 to −38.7 %) and MeanOD for cataract stage 1 (n = 9 eyes): −42.6 % (−46.0 to −26.0 %), stage 2 (n = 26 eyes): −44.1 % (−51.8 to −26.2 %), stage 3 (n = 21 eyes): −45.7 % (−54.7 to −24.7 %), stage 4 (n = 25 eyes): −39.5 % (−59.4 to −26.1 %), and stage 5 (n = 5 eyes): −57.0 % (−66.1 to −51.4 %). As established by comparison of pre- to post-operative measurements, cataract presented a strong effect on MPOD measured by one-wavelength Reflection Method. Particular care should therefore be taken when evaluating MPOD using this Method in elderly patients with progressed stage of cataract. Future optimization of correcting parameters of scattered light and consideration of cataract influence may allow more precise evaluation of MPOD.

  • simple and objective Method for routine detection of the macular pigment xanthophyll
    Journal of Biomedical Optics, 2010
    Co-Authors: D Schweitzer, Jens Dawczynski, Susanne Jentsch, Martin Hammer, Ute E K Wolfschnurrbusch, Sebastian Wolf
    Abstract:

    A new simple Method for two-dimensional determination of optical density of macular pigment xanthophyll (ODx) in clinical routine is based on a single blue-Reflection fundus image. Individual different vignetting is corrected by a shading function. For its construction, nodes are automatically found in structureless image regions. The influence of stray light in elderly crystalline lenses is compensated by a correction function that depends on age. The reproducibility of parameters in a one-wavelength Reflection Method determined for three subjects (47, 61, and 78 years old) was: maxODx = 6.3%, meanODx = 4.6%, volume = 6%, and area = 6% already before stray-light correction. ODx was comparable in pseudophakic and in an eye with a crystalline lens of the same 11 subjects after stray-light correction. Significant correlation in ODx was found between the one-wavelength Reflection Method and the two-wavelength autofluorescence Method for pseudophakic and cataract eyes of 19 patients suffering from dry age-related macular degeneration (AMD) (R(2) = 0.855). In pseudophakic eyes, maxODx was significantly lower for dry AMD (n = 45) (ODx = 0.491±0.102 ODU) than in eyes with healthy fundus (n = 22) (ODx = 0.615±0.103 ODU) (p = 0.000033). Also in eyes with crystalline lens, maxODx was lower in AMD (n = 125) (ODx = 0.610±0.093 ODU) than in healthy subjects (n = 45) (ODx = 0.674±0.098 ODU) (p = 0.00019). No dependence on age was found in the pseudophakic eyes both of healthy subjects and AMD patients.

  • Objective measurement of macular optical density
    Klinische Monatsblatter Fur Augenheilkunde, 2010
    Co-Authors: Jens Dawczynski, Dietrich Schweitzer, Gabrielle E. Lang
    Abstract:

    : Determination of the optical density of the macular pigment may be used for an assessment of the efficacy of oral lutein supplementation in patients with dry AMD. Beside subjective Methods like heterochrome flicker photometry, objective Methods like the 2-wavelength auto-fluorescence Method and the 1-wavelength Reflection Method are in clinical use today. Both Methods show comparable results. For a long-term assessment of the efficacy of oral lutein supplementation, different parameters like mean and maximal optical density as well as the integral over optical density on all pixels ("volume") should be used. The parameter volume often increases also in cases in which other parameters do not change anymore. The 1-wavelength Reflection Method is used for the newly initiated LUTEGA study. This study will investigate the long-term effects of a fixed lutein/omega-3-fatty acid combination on the optical density in patients with dry AMD.