The Experts below are selected from a list of 43356 Experts worldwide ranked by ideXlab platform
Vadim Backman - One of the best experts on this subject based on the ideXlab platform.
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modeling spectral dependence of reduced Scattering Coefficient for continuous random media with the born approximation
IEEE Transactions on Biomedical Engineering, 2010Co-Authors: Jeremy D Rogers, Ilker R Capoglu, Valentina Stoyneva, Vladimir Turzhitsky, Vadim BackmanAbstract:The power law dependence of reduced Scattering Coefficient (μs′) on wavelength (λ) is derived for continuous random media using a three parameter model of index correlation function by applying the Born approximation.
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accuracy of the born approximation in calculating the Scattering Coefficient of biological continuous random media
Optics Letters, 2009Co-Authors: Ilker R Capoglu, Jeremy D Rogers, Allen Taflove, Vadim BackmanAbstract:A rigorous error analysis is presented for the Scattering Coefficient of biological random continuous media in the Born (or single-Scattering) approximation. The analysis is done in two dimensions (2-D) for simplicity of numerical computation. Scattering Coefficients of various tissue-like random media are numerically calculated via statistical finite-difference-time-domain analysis. The results are then checked against analytical formulas for the Scattering Coefficient in the Born approximation. The validity ranges for the correlation length and the refractive index fluctuation strength of the medium are clearly identified. These 2-D results show promise for future 3-D investigations.
Renjian Zhang - One of the best experts on this subject based on the ideXlab platform.
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investigation of hygroscopic growth effect on aerosol Scattering Coefficient at a rural site in the southern north china plain
Science of The Total Environment, 2017Co-Authors: Xiaojia Wang, Peng Yan, Leiming Zhang, Jun Tao, Xinyu Liu, Ping Tian, Zhiwei Han, Renjian ZhangAbstract:Abstract Aerosol optical properties and the effect of hygroscopic growth on the Scattering Coefficients at a rural site in the southern North China Plain were investigated based on a two-month observation conducted in the summer of 2014. The Scattering Coefficient of dry aerosols was high, with a mean (± standard deviation) of 338.8 ± 209.9 Mm − 1 (520 nm) during the observation period. A noticeable enhancement in aerosol Scattering due to hygroscopic growth was observed, e.g., by a factor of 2.28 ± 0.69 at RH of 80% (referred to as f (RH = 80%)) and 3.39 ± 1.14 at RH of 85% ( f (RH = 85%)). The high content of water-soluble secondary inorganic aerosols (SIAs), accounting for 53.1% of fine particulate matter (i.e., PM 2.5 ) on average, was mainly responsible for the high hygroscopicity. f (RH = 80%) increased with increasing SIA mass fraction in PM 2.5 . This was especially the case when SIAs were mainly in finer particulate matter, i.e., PM 1 . A number of considerably low f (RH = 80%) values was observed due to relatively low mass fraction of SIAs in PM 1 despite high fraction in PM 2.5 . Particle size distributions, especially those of SIAs, also played a remarkable role in the hygroscopicity of ambient aerosols. No significant difference in hygroscopicity was found between different pollution episodes due to the dominance of SIAs in all the cases. Slightly higher hygroscopic growth factors were observed during the clean episode, which were attributed to the smaller particle sizes.
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an alternative method for estimating hygroscopic growth factor of aerosol light Scattering Coefficient a case study in an urban area of guangzhou south china
Atmospheric Chemistry and Physics, 2014Co-Authors: Leiming Zhang, Jun Tao, Renjian Zhang, Zhaoyu Lin, Z S Zhang, J J Cao, Shaojia Fan, Y ZhangAbstract:Abstract. A method was developed to estimate hygroscopic growth factor (f(RH)) of aerosol light-Scattering Coefficient (bsp), making use of the measured size- and chemically resolved aerosol samples. In this method, chemical composition of the measured aerosol samples were first reconstructed using the equilibrium model ISORROPIA II. The reconstructed chemical composition, which varies with relative humidity (RH), was then employed to calculate bsp and hygroscopic growth factor of bsp (fsp(RH)) using the Mie model. Furthermore, the calculated fsp(RH) was fitted with an empirical curve. To evaluate the applicability of fsp(RH), the curve of fsp(RH) was used to correct the long-term records of the measured bsp from the values under comparative dry conditions to the ones under ambient RH conditions. Compared with the original bsp data, the fsp(RH)-corrected bsp had a higher linear correlation with, and a smaller discrepancy from, the bsp derived directly from visibility and absorption measurements. The fsp(RH) determined here was further compared with that reported in previous studies. The method described in this manuscript provides an alternative approach to derive credible fsp(RH) with high accuracy and has many potential applications in aerosol-related research.
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hygroscopic growth of aerosol Scattering Coefficient a comparative analysis between urban and suburban sites at winter in beijing
Particuology, 2009Co-Authors: Peng Yan, Renjian Zhang, Xiaole Pan, Jie Tang, Xiuji Zhou, Limin ZengAbstract:Abstract A humidity controlled inlet system was developed to measure the hygroscopic growth of aerosol Scattering Coefficient in conjunction with nephelometry at an urban site of Chinese Academy of Meteorological Sciences (CAMS) in Beijing and a rural site at Shangdianzi Regional Background Air Pollution Monitoring Station (SDZ) outside Beijing during winter, from December 2005 to January 2006. Measurements were carried out at a wavelength of 525 nm with an Ecotech M9003 nephelometer. The hygroscopic growth function (or factor) of the aerosol Scattering Coefficient f (RH) increased continuously with increasing relative humidity (RH) and showed no obvious “step-like” deliquescent behavior at both sites during the experiment. The average growth factor f (RH) at the SDZ site could reach 1.5 when RH increased from less than 40% to 92%, and to 2.1 at the CAMS site when RH increased from less than 40% to 93%. The average hygroscopic growth factor at a relative humidity of 80%, f (RH = 80 ± 1%), was found to be about 1.26 ± 0.15 at CAMS and 1.24 ± 0.11 at SDZ. Further analysis indicated that under relatively polluted conditions, the average hygroscopic growth factor was higher at the CAMS site than that at the SDZ site. However, under relatively clean air conditions, the difference between the two sites was small, showing a hygroscopic growth behavior similar to those of burning biomass or blowing dust. These results reflected the different characteristics of aerosol types at the two sites.
Molly Brewer - One of the best experts on this subject based on the ideXlab platform.
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quantitative analysis of estimated Scattering Coefficient and phase retardation for ovarian tissue characterization
Biomedical Optics Express, 2012Co-Authors: Yi Yang, Tianheng Wang, Melinda Sanders, Xiaohong Wang, Molly BrewerAbstract:In this report, optical Scattering Coefficient and phase retardation quantitatively estimated from polarization-sensitive OCT (PSOCT) were used for ovarian tissue characterization. A total of 33 ex vivo ovaries (normal: n = 26, malignant: n = 7) obtained from 18 patients were investigated. A specificity of 100% and a sensitivity of 86% were achieved by using estimated Scattering Coefficient alone; and a specificity of 100% and a sensitivity of 43% were obtained by using phase retardation alone. However, a superior specificity of 100% and sensitivity of 100% were achieved if these two parameters were used together for classifying normal and malignant ovaries. Quantitative measurement of collagen content obtained from Sirius red histology sections shows that it correlates with estimated Scattering Coefficient and phase retardation. Our initial results demonstrate that quantitative analysis of PSOCT could be a potentially valuable method for distinguishing normal from malignant ovarian tissues during minimally invasive surgery and help guide surgical intervention.
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optical Scattering Coefficient estimated by optical coherence tomography correlates with collagen content in ovarian tissue
Journal of Biomedical Optics, 2011Co-Authors: Yi Yang, Tianheng Wang, Melinda Sanders, Molly Brewer, Xiaohong Wang, Nrusingh C BiswalAbstract:Optical Scattering Coefficient from ex vivo unfixed normal and malignant ovarian tissue was quantitatively extracted by fitting optical coherence tomography (OCT) A-line signals to a single Scattering model. 1097 average A-line measurements at a wavelength of 1310 nm were performed at 108 sites obtained from 18 ovaries. The average Scattering Coefficient obtained from the normal tissue group consisted of 833 measurements from 88 sites was 2.41 mm−1 (±0.59), while the average Coefficient obtained from the malignant tissue group consisted of 264 measurements from 20 sites was 1.55 mm−1 (±0.46). The malignant ovarian tissue showed significant lower Scattering than the normal group (p < 0.001). The amount of collagen within OCT imaging depth was analyzed from the tissue histological section stained with Sirius Red. The average collagen area fraction (CAF) obtained from the normal tissue group was 48.4% (±12.3%), while the average CAF obtained from the malignant tissue group was 11.4% (±4.7%). A statistical significance of the collagen content was found between the two groups (p < 0.001). These results demonstrated that quantitative measurements of optical Scattering Coefficient from OCT images could be a potential powerful method for ovarian cancer detection.
Liu Huating - One of the best experts on this subject based on the ideXlab platform.
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measurement of reduced Scattering Coefficient of c6 glioma rats by near infrared spectroscopy technique
Shandong Medical Journal, 2011Co-Authors: Liu HuatingAbstract:Objective To observe the characteristics of reduced Scattering Coefficient measurement of living C6-glioma rats by near infrared spectroscopy technique.Methods Forty SD rats were randomly divided into 2 groups,C6-glioma group and control group.C6 cells were injected in SD rat caudate nucleus by means of subculture of stereotactic inoculation.When the glioma had grown to 0.5～1.0 cm in diameter as experimental group by MRI detection.A specific designed fiber optical spectrum system was applied to measure the optical parameters(reduced Scattering Coefficient) in 20 C6-glioma rats compared to control group.Results Reduced Scattering Coefficient in experimental group was lower than that in control group(P0.05).Conclusion The near infrared spectroscopy technique can be applied to detect the glioma,and reduced Scattering Coefficient can be used for the glioma quantification.
Matthias Essenpreis - One of the best experts on this subject based on the ideXlab platform.
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correlation between blood glucose concentration in diabetics and noninvasively measured tissue optical Scattering Coefficient
Optics Letters, 1997Co-Authors: Jody T Bruulsema, Joseph E Hayward, Thomas J Farrell, Michael S Patterson, L Heinemann, M Berger, T Koschinsky, J Sandahlchristiansen, H Orskov, Matthias EssenpreisAbstract:Diabetics would benefit greatly from a device capable of providing continuous noninvasive monitoring of their blood glucose levels. The optical Scattering Coefficient of tissue depends on the concentration of glucose in the extracellular fluid. A feasibility study was performed to evaluate the sensitivity of the tissue reduced Scattering Coefficient in response to step changes in the blood glucose levels of diabetic volunteers. Estimates of the Scattering Coefficient were based on measurements of the diffuse reflectance on the skin at distances of 1–10 mm from a point source. A correlation was observed between step changes in blood glucose concentration and tissue reduced Scattering Coefficient in 30 out of 41 subjects measured.
