1
|
Ma M, Powell D, Nassar M, Teckoe J, Markl D, Zeitler JA. Impact of immediate release film coating on the disintegration process of tablets. J Control Release 2024; 373:533-546. [PMID: 39032576 DOI: 10.1016/j.jconrel.2024.07.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 07/12/2024] [Accepted: 07/15/2024] [Indexed: 07/23/2024]
Abstract
Pharmaceutical tablets are often coated with a layer of polymeric material to protect the drug from environmental degradation, facilitate the packaging process, and enhance patient compliance. However, the detailed effects of such coating layers on drug release are not well understood. To investigate this, flat-faced pure microcrystalline cellulose tablets with a diameter of 13 mm and a thickness between 1.5 mm to 1.6 mm were directly compressed, and a film coating layer with a thickness of 80 μm to 120 μm was applied to one face of these tablets. This tablet geometry and immediate release film coating were chosen as a model system to understand how the film coating interacts with the tablet core. The coating hydration and dissolution process was studied using terahertz pulsed imaging, while optical coherence tomography was used to capture further details on the swelling process of the polymer in the coated tablet. The study investigated the film coating polymer dissolution process and found the gelling of dissolving polymer restricted the capillary liquid transport in the core. These findings can help predict the dissolution of film coating within the typical range of thickness (30 μm to 40 μm) and potentially be extended to understand modified release coating formulations.
Collapse
Affiliation(s)
- Mingrui Ma
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
| | - Daniel Powell
- Centre for Continuous Manufacturing and Advanced Crystallisation, University of Strathclyde, Glasgow G1 1RD, UK; Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK
| | - Marwa Nassar
- Colorcon Ltd, Flagship House, Victory Way, Dartford DA2 6QD, UK
| | - Jason Teckoe
- Colorcon Ltd, Flagship House, Victory Way, Dartford DA2 6QD, UK
| | - Daniel Markl
- Centre for Continuous Manufacturing and Advanced Crystallisation, University of Strathclyde, Glasgow G1 1RD, UK; Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK
| | - J Axel Zeitler
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK.
| |
Collapse
|
2
|
Pharmaceutical Coating and Its Different Approaches, a Review. Polymers (Basel) 2022; 14:polym14163318. [PMID: 36015575 PMCID: PMC9415771 DOI: 10.3390/polym14163318] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/28/2022] [Accepted: 07/31/2022] [Indexed: 11/29/2022] Open
Abstract
Coating the solid dosage form, such as tablets, is considered common, but it is a critical process that provides different characteristics to tablets. It increases the value of solid dosage form, administered orally, and thus meets diverse clinical requirements. As tablet coating is a process driven by technology, it relies on advancements in coating techniques, equipment used for the coating process, evaluation of coated tablets, and coated material used. Although different techniques were employed for coating purposes, which may be based on the use of solvents or solvent-free, each of the methods used has its advantages and disadvantages, and the techniques need continued modification too. During the process of film coating, several inter-and intra-batch uniformity of coated material on the tablets is considered a critical point that ensures the worth of the final product, particularly for those drugs that contain an active medicament in the coating layer. Meanwhile, computational modeling and experimental evaluation were actively used to predict the impact of the operational parameters on the final product quality and optimize the variables in tablet coating. The efforts produced by computational modeling or experimental evaluation not only save cost in optimizing the coating process but also saves time. This review delivers a brief review on film coating in solid dosage form, which includes tablets, with a focus on the polymers and processes used in the coating. At the end, some pharmaceutical applications were also discussed.
Collapse
|
3
|
Zhong Z, Liu X, Luo X, Zhu Y, Wang S, Huang Y. Evaluation of coating uniformity for the digestion-aid tablets by portable near-infrared spectroscopy. Int J Pharm 2022; 622:121833. [PMID: 35618177 DOI: 10.1016/j.ijpharm.2022.121833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 04/29/2022] [Accepted: 05/13/2022] [Indexed: 10/18/2022]
Abstract
Process analysis can effectively stabilize pharmaceutical quality and optimize the control of production process. For the sustained-release digestion-aid tablets, the coating film thickness is an important indicator to measure the quality of products. Traditional method mainly spot-checks tablets and measures with visual microscopy, which is time-consuming and laborious. This study attempted to use a portable near-infrared spectroscopy for rapid detection of a Chinese medicine tablets from production line. First, PLS regression models were established for coating film at twelve different locations of the tablet section, and the results showed that the correlation coefficients of training and validation sets were all over 0.80. Subsequently, the twelve locations were divided into six groups to further establish regressions. After chemometrics optimization, the optimal of six group models were generally better than single location models, with Rc2 and Rv2 all above 0.85, and RMSEV values all below 2.0. The mean relative error of prediction of the optimal model was 9.49%. The pharmaceutical process detection based on the portable NIR spectroscopy met the demand of managing digestion-aid tablet coating data conveniently. The proposed approach can successfully realize on-site and online pharmaceutical monitoring and has a promising practical value.
Collapse
Affiliation(s)
- Zhijian Zhong
- Technology and Innovation Center of Jiangxi Traditional Chinese Medicine Manufacturing and Process Quality Control, Nanchang, Jiangxi 330004, PR China; Research Center of CR Jiangzhong Pharmaceutical Group Co. Ltd, Nanchang, Jiangxi 330096, PR China
| | - Xuhai Liu
- Technology and Innovation Center of Jiangxi Traditional Chinese Medicine Manufacturing and Process Quality Control, Nanchang, Jiangxi 330004, PR China; Research Center of CR Jiangzhong Pharmaceutical Group Co. Ltd, Nanchang, Jiangxi 330096, PR China
| | - Xiaorong Luo
- Technology and Innovation Center of Jiangxi Traditional Chinese Medicine Manufacturing and Process Quality Control, Nanchang, Jiangxi 330004, PR China
| | - Yewei Zhu
- Beijing Great Tech Technology Co. Ltd, Beijing 100142, PR China
| | - Shuai Wang
- Beijing Great Tech Technology Co. Ltd, Beijing 100142, PR China
| | - Yue Huang
- Technology and Innovation Center of Jiangxi Traditional Chinese Medicine Manufacturing and Process Quality Control, Nanchang, Jiangxi 330004, PR China; College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China.
| |
Collapse
|
4
|
Towards a Better Understanding of Verapamil Release from Kollicoat SR:IR Coated Pellets Using Non-Invasive Analytical Tools. Pharmaceutics 2021; 13:pharmaceutics13101723. [PMID: 34684015 PMCID: PMC8541620 DOI: 10.3390/pharmaceutics13101723] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/10/2021] [Accepted: 10/11/2021] [Indexed: 11/18/2022] Open
Abstract
The aim of this study was to gain deeper insight into the mass transport mechanisms controlling drug release from polymer-coated pellets using non-invasive analytical tools. Pellet starter cores loaded with verapamil HCl (10% loading, 45% lactose, 45% microcrystalline cellulose) were prepared by extrusion/spheronization and coated with 5% Kollicoat SR:IR 95:5 or 10% Kollicoat SR:IR 90:10. Drug release was measured from ensembles of pellets as well as from single pellets upon exposure to acetate buffer pH = 3.5 and phosphate buffer pH = 7.4. The swelling of single pellets was observed by optical microscopy, while dynamic changes in the pH in the pellet cores were monitored by fluorescence spectroscopy. Also, mathematical modeling using a mechanistically realistic theory as well as SEM and Raman imaging were applied to elucidate whether drug release mainly occurs by diffusion through the intact film coatings or whether crack formation in the film coatings plays a role. Interestingly, fluorescence spectroscopy revealed that the pH within the pellet cores substantially differed upon exposure to acetate buffer pH = 3.5 and phosphate buffer pH = 7.4, resulting in significant differences in drug solubility (verapamil being a weak base) and faster drug release at lower pH: from ensembles of pellets and single pellets. The monitoring of drug release from and the swelling of single pellets indicated that crack formation in the film coatings likely plays a major role, irrespective of the Kollicoat SR:IR ratio/coating level. This was confirmed by mathematical modeling, SEM and Raman imaging. Importantly, the latter technique allowed also for non-invasive measurements, reducing the risk of artifact creation associated with sample cutting with a scalpel.
Collapse
|
5
|
Tran PHL, Tran TTD. The Use of Natural Materials in Film Coating for Controlled Oral Drug Release. Curr Med Chem 2021; 28:1829-1840. [PMID: 32164506 DOI: 10.2174/0929867327666200312113547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/30/2020] [Accepted: 02/18/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Although synthetic materials have been used in film coating processes for drug delivery for many years, substantial studies on natural materials have also been conducted because of their biodegradable and unique properties. METHODS Because of the ability to form and modify films for controlled oral drug delivery, increasing attention has been shown to these materials in the design of film coating systems in recent research. RESULTS This review aims to provide an overview of natural materials focusing on film coating for oral delivery, specifically in terms of their classification and their combinations in film coating formulations for adjusting the desired properties for controlled drug delivery. CONCLUSIONS Discussing natural materials and their potential applications in film coating would benefit the optimization of processes and strategies for future utilization.
Collapse
Affiliation(s)
| | - Thao Truong-Dinh Tran
- Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Vietnam
| |
Collapse
|
6
|
Seo KS, Bajracharya R, Lee SH, Han HK. Pharmaceutical Application of Tablet Film Coating. Pharmaceutics 2020; 12:pharmaceutics12090853. [PMID: 32911720 PMCID: PMC7558083 DOI: 10.3390/pharmaceutics12090853] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 08/27/2020] [Accepted: 09/03/2020] [Indexed: 12/27/2022] Open
Abstract
Tablet film coating is a common but critical process providing various functionalities to tablets, thereby meeting diverse clinical needs and increasing the value of oral solid dosage forms. Tablet film coating is a technology-driven process and the evolution of coated dosage forms relies on advancements in coating technology, equipment, analytical techniques, and coating materials. Although multiple coating techniques are developed for solvent-based or solvent-free coating processes, each method has advantages and disadvantages that may require continuous technical refinement. In the film coating process, intra- and inter-batch coating uniformity of tablets is critical to ensure the quality of the final product, especially for active film coating containing active pharmaceutical ingredients in the coating layer. In addition to experimental evaluation, computational modeling is also actively pursued to predict the influence of operation parameters on the quality of the final product and optimize process variables of tablet film coating. The concerted efforts of experiments and computational modeling can save time and cost in optimizing the tablet coating process. This review provides a brief overview of tablet film coating technology and modeling approaches with a focus on recent advancements in pharmaceutical applications.
Collapse
Affiliation(s)
- Ki-Soo Seo
- College of Pharmacy, Dongguk University-Seoul, Dongguk-ro-32, Ilsan-Donggu, Goyang 10326, Korea; (K.-S.S.); (R.B.); (S.H.L.)
- Research Institute, Dong Wha Pharm., Tapsil-ro-35, Giheung-gu, Yongin 17084, Korea
| | - Rajiv Bajracharya
- College of Pharmacy, Dongguk University-Seoul, Dongguk-ro-32, Ilsan-Donggu, Goyang 10326, Korea; (K.-S.S.); (R.B.); (S.H.L.)
| | - Sang Hoon Lee
- College of Pharmacy, Dongguk University-Seoul, Dongguk-ro-32, Ilsan-Donggu, Goyang 10326, Korea; (K.-S.S.); (R.B.); (S.H.L.)
| | - Hyo-Kyung Han
- College of Pharmacy, Dongguk University-Seoul, Dongguk-ro-32, Ilsan-Donggu, Goyang 10326, Korea; (K.-S.S.); (R.B.); (S.H.L.)
- Correspondence: ; Tel.: +82-31-961-5217; Fax: +82-31-961-5206
| |
Collapse
|
7
|
Feng H, Mohan S. Application of Process Analytical Technology for Pharmaceutical Coating: Challenges, Pitfalls, and Trends. AAPS PharmSciTech 2020; 21:179. [PMID: 32596747 DOI: 10.1208/s12249-020-01727-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/08/2020] [Indexed: 12/31/2022] Open
Abstract
Coating process is a critical unit operation for manufacturing solid oral dosage forms. For a long time, the coating weight gain has been discerned as the most important, if not only, characteristic describing the coating quality. As the introduction of quality by design (QbD) and advancement of process analytical technology (PAT), nowadays more techniques are available to analyze other quality attributes which have been overlooked but have substantial impacts on the performance of coated products. The techniques that permit rapid and non-destructive measurements are of particular importance to improve process operation and product quality. This article reviews the analytical techniques that have been and potentially could be used as PAT tools for characterizing the quality of pharmaceutical coating product. By identifying the challenges and pitfalls encountered during PAT application, the review aims at fostering the adoption of PAT for paving the way to enhanced quality and efficiency of the coating processes.
Collapse
Affiliation(s)
- Hanzhou Feng
- Process analytical technology, Merck & Co., Inc., Rahway, New Jersey, USA.
| | - Shikhar Mohan
- Graduate School of Pharmaceutical Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, Pennsylvania, USA
| |
Collapse
|
8
|
Alves-Lima D, Song J, Li X, Portieri A, Shen Y, Zeitler JA, Lin H. Review of Terahertz Pulsed Imaging for Pharmaceutical Film Coating Analysis. SENSORS (BASEL, SWITZERLAND) 2020; 20:E1441. [PMID: 32155785 PMCID: PMC7085697 DOI: 10.3390/s20051441] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/27/2020] [Accepted: 03/02/2020] [Indexed: 12/02/2022]
Abstract
Terahertz pulsed imaging (TPI) was introduced approximately fifteen years ago and has attracted a lot of interest in the pharmaceutical industry as a fast, non-destructive modality for quantifying film coatings on pharmaceutical dosage forms. In this topical review, we look back at the use of TPI for analysing pharmaceutical film coatings, highlighting the main contributions made and outlining the key challenges ahead.
Collapse
Affiliation(s)
- Décio Alves-Lima
- Department of Engineering, Lancaster University, Lancaster LA1 4YW, UK; (D.A.-L.); (J.S.); (X.L.)
| | - Jun Song
- Department of Engineering, Lancaster University, Lancaster LA1 4YW, UK; (D.A.-L.); (J.S.); (X.L.)
- Department of Information Science, Nanjing Forestry University, Nanjing 210037, Jiangsu, China
| | - Xiaoran Li
- Department of Engineering, Lancaster University, Lancaster LA1 4YW, UK; (D.A.-L.); (J.S.); (X.L.)
| | - Alessia Portieri
- TeraView Ltd., 1, Enterprise Cambridge Research Park, Cambridge CB25 9PD, UK;
| | - Yaochun Shen
- Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool L69 3GJ, UK;
| | - J. Axel Zeitler
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK;
| | - Hungyen Lin
- Department of Engineering, Lancaster University, Lancaster LA1 4YW, UK; (D.A.-L.); (J.S.); (X.L.)
| |
Collapse
|
9
|
Sacher S, Wahl P, Weißensteiner M, Wolfgang M, Pokhilchuk Y, Looser B, Thies J, Raffa A, Khinast JG. Shedding light on coatings: Real-time monitoring of coating quality at industrial scale. Int J Pharm 2019; 566:57-66. [DOI: 10.1016/j.ijpharm.2019.05.048] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 10/26/2022]
|
10
|
Kuwahara R, Tomita R, Ogawa N, Nakajima K, Takeda T, Uehara H, Yamanobe T. Crystallization and hardening of poly(ethylene-co-vinyl acetate) mouthguards during routine use. Sci Rep 2017; 7:44672. [PMID: 28294184 PMCID: PMC5353674 DOI: 10.1038/srep44672] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 02/13/2017] [Indexed: 11/24/2022] Open
Abstract
Mouthguards (MGs) made from poly(ethylene-co-vinyl acetate) (EVA) are widely used in contact sports to prevent injuries such as breaking teeth and lip lacerations and to reduce brain concussion. However, the changes in morphology and the molecular mobility of EVA, which can affect its physical properties during practical usage, have not been precisely examined. Therefore, we attempted to determine the main factors which lead to changes in MG performance after one season of practical use by high school rugby players. Solid-state nuclear magnetic resonance (NMR) and pulse NMR measurements showed the hardening of MGs, which was associated with an increased crystallinity of the EVA resulting from prolonged usage. Furthermore, our data indicated that the increase in the relative amount of the crystalline phase may be primarily attributed to temperature fluctuations and repeated changes in pressure, which could cause the hardening of EVA and eventually diminish the protective ability of MGs.
Collapse
Affiliation(s)
- Ryoko Kuwahara
- Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan
| | - Ryotaro Tomita
- Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan
| | - Natsumi Ogawa
- Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan
| | - Kazunori Nakajima
- Department of Oral Health and Clinical Science, Division of Sports Dentistry, Tokyo Dental College, Chiyoda-ku, Tokyo, Japan
| | - Tomotaka Takeda
- Department of Oral Health and Clinical Science, Division of Sports Dentistry, Tokyo Dental College, Chiyoda-ku, Tokyo, Japan
| | - Hiroki Uehara
- Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan
| | - Takeshi Yamanobe
- Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu, Gunma, Japan
| |
Collapse
|
11
|
Yin X, Hadjiloucas S, Zhang Y. Classification of THz pulse signals using two-dimensional cross-correlation feature extraction and non-linear classifiers. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2016; 127:64-82. [PMID: 27000290 DOI: 10.1016/j.cmpb.2016.01.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 01/20/2016] [Accepted: 01/21/2016] [Indexed: 05/14/2023]
Abstract
This work provides a performance comparison of four different machine learning classifiers: multinomial logistic regression with ridge estimators (MLR) classifier, k-nearest neighbours (KNN), support vector machine (SVM) and naïve Bayes (NB) as applied to terahertz (THz) transient time domain sequences associated with pixelated images of different powder samples. The six substances considered, although have similar optical properties, their complex insertion loss at the THz part of the spectrum is significantly different because of differences in both their frequency dependent THz extinction coefficient as well as differences in their refractive index and scattering properties. As scattering can be unquantifiable in many spectroscopic experiments, classification solely on differences in complex insertion loss can be inconclusive. The problem is addressed using two-dimensional (2-D) cross-correlations between background and sample interferograms, these ensure good noise suppression of the datasets and provide a range of statistical features that are subsequently used as inputs to the above classifiers. A cross-validation procedure is adopted to assess the performance of the classifiers. Firstly the measurements related to samples that had thicknesses of 2mm were classified, then samples at thicknesses of 4mm, and after that 3mm were classified and the success rate and consistency of each classifier was recorded. In addition, mixtures having thicknesses of 2 and 4mm as well as mixtures of 2, 3 and 4mm were presented simultaneously to all classifiers. This approach provided further cross-validation of the classification consistency of each algorithm. The results confirm the superiority in classification accuracy and robustness of the MLR (least accuracy 88.24%) and KNN (least accuracy 90.19%) algorithms which consistently outperformed the SVM (least accuracy 74.51%) and NB (least accuracy 56.86%) classifiers for the same number of feature vectors across all studies. The work establishes a general methodology for assessing the performance of other hyperspectral dataset classifiers on the basis of 2-D cross-correlations in far-infrared spectroscopy or other parts of the electromagnetic spectrum. It also advances the wider proliferation of automated THz imaging systems across new application areas e.g., biomedical imaging, industrial processing and quality control where interpretation of hyperspectral images is still under development.
Collapse
Affiliation(s)
- Xiaoxia Yin
- Centre for Applied Informatics, College of Engineering & Science, Victoria University, Melbourne, Australia.
| | - Sillas Hadjiloucas
- School of Systems Engineering, University of Reading, Reading RG6 6AY, UK.
| | - Yanchun Zhang
- Centre for Applied Informatics, College of Engineering & Science, Victoria University, Melbourne, Australia.
| |
Collapse
|
12
|
Pharmaceutical Terahertz Spectroscopy and Imaging. ADVANCES IN DELIVERY SCIENCE AND TECHNOLOGY 2016. [DOI: 10.1007/978-1-4939-4029-5_5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
|
13
|
Agrawal AM, Pandey P. Scale Up of Pan Coating Process Using Quality by Design Principles. J Pharm Sci 2015. [DOI: 10.1002/jps.24582] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
14
|
Fan S, Qi F, Notake T, Nawata K, Takida Y, Matsukawa T, Minamide H. Diffraction-limited real-time terahertz imaging by optical frequency up-conversion in a DAST crystal. OPTICS EXPRESS 2015; 23:7611-7618. [PMID: 25837099 DOI: 10.1364/oe.23.007611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Real-time terahertz (THz) wave imaging has wide applications in areas such as security, industry, biology, medicine, pharmacy, and the arts. This report describes real-time room-temperature THz imaging by nonlinear optical frequency up-conversion in an organic 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate (DAST) crystal, with high resolution reaching the diffraction limit. THz-wave images were converted to the near infrared region and then captured using an InGaAs camera in a tandem imaging system. The resolution of the imaging system was analyzed. Diffraction and interference of THz wave were observed in the experiments. Videos are supplied to show the interference pattern variation that occurs with sample moving and tilting.
Collapse
|
15
|
How to easily provide zero order release of freely soluble drugs from coated pellets. Int J Pharm 2015; 478:31-38. [DOI: 10.1016/j.ijpharm.2014.10.071] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 10/28/2014] [Accepted: 10/31/2014] [Indexed: 11/21/2022]
|