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Axel J Zeitler - One of the best experts on this subject based on the ideXlab platform.

  • quantifying pharmaceutical Film Coating with optical coherence tomography and terahertz pulsed imaging an evaluation
    Journal of Pharmaceutical Sciences, 2015
    Co-Authors: Hungyen Lin, Yue Dong, Yaochun Shen, Axel J Zeitler
    Abstract:

    Spectral domain optical coherence tomography (OCT) has recently attracted a lot of interest in the pharmaceutical industry as a fast and non-destructive modality for quantification of thin Film Coatings that cannot easily be resolved with other techniques. Because of the relative infancy of this technique, much of the research to date has focused on developing the in-line measurement technique for assessing Film Coating thickness. To better assess OCT for pharmaceutical Coating quantification, this paper evaluates tablets with a range of Film Coating thickness measured using OCT and terahertz pulsed imaging (TPI) in an off-line setting. In order to facilitate automated Coating quantification for Film Coating thickness in the range of 30–200 μm, an algorithm that uses wavelet denoising and a tailored peak finding method is proposed to analyse each of the acquired A-scan. Results obtained from running the algorithm reveal an increasing disparity between the TPI and OCT measured intra-tablet variability when Film Coating thickness exceeds 100 μm. The finding further confirms that OCT is a suitable modality for characterising pharmaceutical dosage forms with thin Film Coatings, whereas TPI is well suited for thick Coatings. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3377–3385, 2015

  • terahertz pulsed imaging as an analytical tool for sustained release tablet Film Coating
    European Journal of Pharmaceutics and Biopharmaceutics, 2009
    Co-Authors: Ronny Muller, Yaochun Shen, Keith C Gordon, Peter Kleinebudde, M Pepper, Thomas Rades, P F Taday, Axel J Zeitler
    Abstract:

    Abstract The ability of terahertz pulsed imaging (TPI) to be employed as an analytical tool for monitoring a Film Coating unit operation and to assess the success of a subsequent process scale-up was explored in this study. As part of a process scale-up development, a total of 190 sustained-release tablets were sampled at 10% increments of the amount of polymer applied, from a lab-scale and a pilot-scale Coating run. These tablets were subjected to TPI analysis, followed by dissolution testing. Information on tablet Film Coating layer thickness and variations in Coating density were extracted using TPI. It was found that both terahertz parameters were more sensitive and informative to product quality when compared with measuring the amount of polymer applied. For monitoring the Film Coating unit operation, Coating layer thickness showed a strong influence on the dissolution behaviour for both the lab-scale and the pilot-scale batches. An R 2 of 0.89, root mean square error (RMSE) = 0.22 h (MDT range = 3.21–5.48 h) and an R 2 of 0.92, RMSE = 0.23 h (MDT range = 5.43–8.12 h) were derived from the lab-scale and pilot-scale, respectively. The scale-up process led to significant changes in MDT between the lab-scale and pilot-scale. These changes in MDT could be explained by the differences observed in the Film Coating density on samples with similar amount of polymer applied between the lab and the pilot-scale. Overall, TPI demonstrated potential to be employed as an analytical tool to help refine the Coating unit operation and the scale-up procedure.

Yaochun Shen - One of the best experts on this subject based on the ideXlab platform.

  • quantifying pharmaceutical Film Coating with optical coherence tomography and terahertz pulsed imaging an evaluation
    Journal of Pharmaceutical Sciences, 2015
    Co-Authors: Hungyen Lin, Yue Dong, Yaochun Shen, Axel J Zeitler
    Abstract:

    Spectral domain optical coherence tomography (OCT) has recently attracted a lot of interest in the pharmaceutical industry as a fast and non-destructive modality for quantification of thin Film Coatings that cannot easily be resolved with other techniques. Because of the relative infancy of this technique, much of the research to date has focused on developing the in-line measurement technique for assessing Film Coating thickness. To better assess OCT for pharmaceutical Coating quantification, this paper evaluates tablets with a range of Film Coating thickness measured using OCT and terahertz pulsed imaging (TPI) in an off-line setting. In order to facilitate automated Coating quantification for Film Coating thickness in the range of 30–200 μm, an algorithm that uses wavelet denoising and a tailored peak finding method is proposed to analyse each of the acquired A-scan. Results obtained from running the algorithm reveal an increasing disparity between the TPI and OCT measured intra-tablet variability when Film Coating thickness exceeds 100 μm. The finding further confirms that OCT is a suitable modality for characterising pharmaceutical dosage forms with thin Film Coatings, whereas TPI is well suited for thick Coatings. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3377–3385, 2015

  • terahertz pulsed imaging as an analytical tool for sustained release tablet Film Coating
    European Journal of Pharmaceutics and Biopharmaceutics, 2009
    Co-Authors: Ronny Muller, Yaochun Shen, Keith C Gordon, Peter Kleinebudde, M Pepper, Thomas Rades, P F Taday, Axel J Zeitler
    Abstract:

    Abstract The ability of terahertz pulsed imaging (TPI) to be employed as an analytical tool for monitoring a Film Coating unit operation and to assess the success of a subsequent process scale-up was explored in this study. As part of a process scale-up development, a total of 190 sustained-release tablets were sampled at 10% increments of the amount of polymer applied, from a lab-scale and a pilot-scale Coating run. These tablets were subjected to TPI analysis, followed by dissolution testing. Information on tablet Film Coating layer thickness and variations in Coating density were extracted using TPI. It was found that both terahertz parameters were more sensitive and informative to product quality when compared with measuring the amount of polymer applied. For monitoring the Film Coating unit operation, Coating layer thickness showed a strong influence on the dissolution behaviour for both the lab-scale and the pilot-scale batches. An R 2 of 0.89, root mean square error (RMSE) = 0.22 h (MDT range = 3.21–5.48 h) and an R 2 of 0.92, RMSE = 0.23 h (MDT range = 5.43–8.12 h) were derived from the lab-scale and pilot-scale, respectively. The scale-up process led to significant changes in MDT between the lab-scale and pilot-scale. These changes in MDT could be explained by the differences observed in the Film Coating density on samples with similar amount of polymer applied between the lab and the pilot-scale. Overall, TPI demonstrated potential to be employed as an analytical tool to help refine the Coating unit operation and the scale-up procedure.

T.W Huan - One of the best experts on this subject based on the ideXlab platform.

  • Lighting and energy performance of solar Film Coating in air-conditioned cellular offices
    Renewable Energy, 2004
    Co-Authors: Danny H.w. Li, Chris C.s. Lau, Joseph C Lam, T.W Huan
    Abstract:

    In subtropical Hong Kong, the principal objectives of fenestration design include eliminating direct sunlight and decreasing cooling loads. To avoid the problems of glare, excessive brightness and thermal discomfort, occupants may block the windows with internal shading devices, resulting in poor daylighting performance and very small amount of electric lighting energy savings. Recently, the advances in thin Film Coatings for window glass products provide a means of substantially reducing heat gain without proportionally reducing daylight transmittance. It has been suggested that Film Coatings together with photoelectric lighting control systems could minimise the electric lighting and cooling requirements without causing undue visual and thermal discomfort to the occupants. This paper presents field measurements on solar control Film Coatings in fully air-conditioned offices in Hong Kong. Solar heat gains, indoor illuminance levels and the electricity consumption by the fluorescent luminaires were systematically recorded and analysed. Measurements were made for two cellular offices, one with solar control Film Coating on the window glass and the other without. The findings showed that the solar Film Coating could cut down energy expenditures for air-conditioned buildings, especially for spaces with large glazing areas subject to substantial amount of direct sunlight. Results are presented and the design implications discussed.

M Pepper - One of the best experts on this subject based on the ideXlab platform.

  • terahertz pulsed imaging as an analytical tool for sustained release tablet Film Coating
    European Journal of Pharmaceutics and Biopharmaceutics, 2009
    Co-Authors: Ronny Muller, Yaochun Shen, Keith C Gordon, Peter Kleinebudde, M Pepper, Thomas Rades, P F Taday, Axel J Zeitler
    Abstract:

    Abstract The ability of terahertz pulsed imaging (TPI) to be employed as an analytical tool for monitoring a Film Coating unit operation and to assess the success of a subsequent process scale-up was explored in this study. As part of a process scale-up development, a total of 190 sustained-release tablets were sampled at 10% increments of the amount of polymer applied, from a lab-scale and a pilot-scale Coating run. These tablets were subjected to TPI analysis, followed by dissolution testing. Information on tablet Film Coating layer thickness and variations in Coating density were extracted using TPI. It was found that both terahertz parameters were more sensitive and informative to product quality when compared with measuring the amount of polymer applied. For monitoring the Film Coating unit operation, Coating layer thickness showed a strong influence on the dissolution behaviour for both the lab-scale and the pilot-scale batches. An R 2 of 0.89, root mean square error (RMSE) = 0.22 h (MDT range = 3.21–5.48 h) and an R 2 of 0.92, RMSE = 0.23 h (MDT range = 5.43–8.12 h) were derived from the lab-scale and pilot-scale, respectively. The scale-up process led to significant changes in MDT between the lab-scale and pilot-scale. These changes in MDT could be explained by the differences observed in the Film Coating density on samples with similar amount of polymer applied between the lab and the pilot-scale. Overall, TPI demonstrated potential to be employed as an analytical tool to help refine the Coating unit operation and the scale-up procedure.

Karsten Rottwitt - One of the best experts on this subject based on the ideXlab platform.

  • Experimentally Validated Dispersion Tailoring in a Silicon Strip Waveguide With Alumina Thin-Film Coating
    IEEE Photonics Journal, 2018
    Co-Authors: Jesper Bjerge Christensen, Haiyan Ou, Erik Christensen, Yunhong Ding, Karsten Rottwitt
    Abstract:

    We propose a silicon strip waveguide structure with alumina thin-Film Coating in-between the core and the cladding for group-velocity dispersion tailoring. By carefully designing the core dimension and the Coating thickness, a spectrally-flattened near-zero anomalous group-velocity dispersion within the telecom spectral range is obtained, which is predicted to significantly broaden the bandwidth of four-wave mixing. We validate this by characterizing the wavelength conversion in a waveguide sample by atomic layer deposition technology, which to our best knowledge is the first experimental demonstration of the proposed structure. Due to the alumina thin-Film Coating, the wavelength conversion bandwidth reaches $58\,\mathrm{nm}$, an increase by a factor of 1.3 compared to the corresponding structure without Coating. This method can also be applied to other material platforms and applications requiring accurate group-velocity dispersion control.

  • Dispersion tailoring of a silicon strip waveguide employing Titania-Alumina thin-Film Coating
    2017 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), 2017
    Co-Authors: Jesper Bjerge Christensen, Haiyan Ou, Erik Christensen, Yunhong Ding, Karsten Rottwitt
    Abstract:

    We numerically demonstrate dispersion tailoring of a silicon strip waveguide employing Titania-Alumina thin-Film Coating using a finite-difference mode solver. The proposed structure exhibits spectrally-flattened near-zero anomalous dispersion within the telecom wavelength range. We also numerically predict the wavelength conversion efficiency for degenerate four-wave mixing, and obtain a 3 dB bandwidth of 80 nm.