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Abstract
Coronal loops exist ubiquitously in the solar atmosphere. These loops puzzle astronomers over half a century. Solar magneto-seismology (SMS) provides a unique way to constrain the physical parameters of coronal loops. Here, we study the evolution of oscillations of a coronal loop observed by the Atmospheric Imaging Assembly (AIA). We measure geometric and physical parameters of the loop oscillations. In particular, we find that the mean period of the oscillations increased from 1048 to 1264 s during three oscillatory cycles. We employ the differential emission measure method and apply the tools of SMS. The evolution of densities inside and outside the loop is analyzed. We found that an increase of density inside the loop and decrease of the magnetic field strength along the loop are the main reasons for the increase in the period during the oscillations. Besides, we also found that the amplitude profile of the loop is different from a profile would it be a homogeneous loop. It is proposed that the distribution of magnetic strength along the loop rather than density stratification is responsible for this deviation. The variation in period and distribution of amplitude provide, in terms of SMS, a new and unprecedented insight into coronal loop diagnostics.
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Affiliation(s)
- W Su
- School of Physics and MOE Key Laboratory of Fundamental Physical Quantities Measurements, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei Province, 430074, China. .,Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Nanjing, 210008, China. .,Key Laboratory for Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing, 210023, China. .,Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China.
| | - Y Guo
- Key Laboratory for Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing, 210023, China
| | - R Erdélyi
- Solar Physics and Space Plasma Research Centre (SP2RC), University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, UK.,Department of Astronomy, Eötvös Loránd University, Pázmány P. sétány 1/a, Budapest, H-1117, Hungary
| | - Z J Ning
- Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Nanjing, 210008, China.
| | - M D Ding
- Key Laboratory for Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing, 210023, China
| | - X Cheng
- Key Laboratory for Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing, 210023, China
| | - B L Tan
- Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China
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Abstract
ABSTRACT
This investigation examined the susceptibility to staining and translucency changes of some new tooth-colored restorative materials after immersion in different beverages. The materials studied were 3M Filtek Z350XT (ZT), 3M Filtek 350XT Flowable Restorative (ZF), Shofu Beautifil Flow Plus (BF), Shofu Beautifil II (B2), 3M Ketac Nano (N100), and 3M Photac Fil (PF). Following the manufacturers' instructions, 42 samples were made from each material and placed in an incubator at 100% humidity and 37°Celsius for 24 hours. Baseline L*, a*, b* readings were taken against white and black backgrounds using a photospectrometer. The samples were then randomly assigned to be immersed in seven beverages, namely cola drink, orange juice, red wine, vodka, black coffee, green tea, and distilled water for a period of seven days. Color readings were taken again by recording the L*, a*, b* values. Data was analyzed using t-tests, one-way analysis of variance with Tukey post hoc and Pearson's correlation (p<0.05). BF generally performed as well as the conventional composite resin materials (ZT and ZF) but N100 and B2 did not. PF had the largest staining and translucency changes. Coffee, red wine, and tea resulted in the most staining and negative translucency changes. An inverse correlation between ΔE and ΔTP was observed for all materials and beverages with the exception of orange juice.
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Affiliation(s)
- BL Tan
- Bing Liang Tan, undergraduate, National Faculty of Dentistry, University Singapore, Singapore, Singapore
| | - AUJ Yap
- Adrian U J. Yap, PhD. MSc, BDS, Grad Dip Psychotherapy, Department of Dentistry, Jurong Health Services; Faculty of Dentistry, National University of Singapore; School of Science and Technology, SIM University, Singapore
| | - HNT Ma
- Han Ni Tun Ma, undergraduate student, Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - J Chew
- Jacob Ren Jie Chew, undergraduate student, Faculty of Dentistry, National University of Singapore, Singapore, Singapore
| | - WJ Tan
- Bing Liang Tan, undergraduate, National Faculty of Dentistry, University Singapore, Singapore, Singapore
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Tan BL, Norhaizan ME, Yeap SK, Roselina K. Water extract of brewers' rice induces antiproliferation of human colorectal cancer (HT-29) cell lines via the induction of apoptosis. Eur Rev Med Pharmacol Sci 2015; 19:1022-1029. [PMID: 25855928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
OBJECTIVE Brewers' rice, a mixture of broken rice, rice bran, and rice germ, is a rice by-product in the rice industry. The present study was designed to investigate the in vitro cytotoxicity of the water extract of brewers' rice (WBR) against colorectal cancer (HT-29) cells. MATERIALS AND METHODS The cytotoxicity activity was determined using the lactate dehydrogenase (LDH) assay. The morphological changes of the HT-29 cells were observed using inverted light and fluorescence microscope. Cell cycle and apoptotic cell death analyses were performed using flow cytometer. Besides that, the selected polyphenolic compounds in WBR were also analyzed using ultra performance liquid chromatography (UPLC). RESULTS The cytotoxicity results showed that WBR was more cytotoxic (but not significantly different) in HT-29 cells compared to the MBR, with IC50 value of 21.88 ± 12.43 µg/mL and 34.50 ± 5.92 µg/mL for WBR and MBR, respectively (p > 0.05). WBR-treated HT-29 cells displayed the typical characteristics of apoptosis, as visualized using inverted light and fluorescence microscope. WBR also significantly increased the number of early and late apoptotic HT-29 cells compared to control cells (p < 0.05). Results from UPLC analysis demonstrated that ferulic acid (36.42 ± 2.97 µg/g) was found the highest level in WBR, followed by gallic acid (26.09 ± 2.01 µg/g) and p-coumaric acid (7.13 ± 0.36 µg/g). These phenolics are speculated to partially contribute to apoptotic cell death. CONCLUSIONS Our results suggested that WBR derived from natural sources might represent a potential chemopreventive agent against colon cancer.
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Affiliation(s)
- B L Tan
- Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
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Chua HC, Chan LL, Chee KS, Chen YH, Chin SA, Chua PLW, Fones SLC, Fung D, Khoo CL, Kwek SKD, Lim ECL, Ling J, Poh P, Sim K, Tan BL, Tan CH, Tan LL, Tan YHC, Tay WK, Yeo C, Su HCA. Ministry of Health clinical practice guidelines: depression. Singapore Med J 2012; 53:137-144. [PMID: 22337190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The Ministry of Health (MOH) have updated the clinical practice guidelines on Depression to provide doctors and patients in Singapore with evidence-based treatment for depression. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the MOH clinical practice guidelines on Depression, for the information of readers of the Singapore Medical Journal. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Ministry of Health website: http://www.moh.gov.sg/content/moh_web/home/Publications/guidelines/cpg/2012/depression.html. The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.
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Affiliation(s)
- H C Chua
- Alexandra Hospital/Jurong Health Services, Singapore
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Verma S, Chan LL, Chee KS, Chen H, Chin SA, Chong SA, Chua W, Fones C, Fung D, Khoo CL, Kwek SKD, Ling J, Poh P, Sim K, Tan BL, Tan C, Tan CH, Tan LL, Tay WK. Ministry of Health clinical practice guidelines: schizophrenia. Singapore Med J 2011; 52:521-526. [PMID: 21808964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The Ministry of Health (MOH) has updated the clinical practice guidelines on Schizophrenia to provide doctors and patients in Singapore with evidence-based treatment for schizophrenia. This article reproduces the introduction and executive summary (with recommendations from the guidelines) from the MOH clinical practice guidelines on Schizophrenia, for the information of readers of the Singapore Medical Journal. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Ministry of Health website: http://www.moh.gov. sg/mohcorp/publications.aspx?id=26138. The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.
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Affiliation(s)
- S Verma
- Ang Mo Kio Polyclinic, Singapore.
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Tan BL, Lim TA. Factors influencing post-operative hyperglycaemia in type 2 diabetes mellitus patients managed without intra-operative insulin. Med J Malaysia 2006; 61:122-4. [PMID: 16708751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Surgery induces a 'stress' state leading to post-operative hyperglycaemia. To investigate this effect on patients with Type 2 Diabetes Mellitus, we reviewed the records of 50 diabetic patients who underwent surgery without intraoperative insulin. Demographic features together with pre-operative and post-operative blood glucose readings were noted. 27.3% of patients with well controlled pre-operative blood glucose levels developed post-operative hyperglycaemia. In contrast, 84.6% of patients with poorly controlled levels developed the same. Poor control of blood glucose and duration of operation were the only significant predictors of post-operative hyperglycaemia.
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Affiliation(s)
- B L Tan
- Anaesthesiology Unit, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia
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Tan BL, Sarafis V, Beattie GAC, White R, Darley EM, Spooner-Hart R. Localization and movement of mineral oil in plants by fluorescence and confocal microscopy. J Exp Bot 2005; 56:2755-63. [PMID: 16118255 DOI: 10.1093/jxb/eri269] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Fluorescence and confocal laser scanning microscopy were explored to investigate the movement and localization of mineral oils in citrus. In a laboratory experiment, fluorescence microscopy observation indicated that when a 'narrow' distillation fraction of an nC23 horticultural mineral oil was applied to adaxial and opposing abaxial leaf surfaces of potted orange [Citrus x aurantium L. (Sapindales: Rutaceae)] trees, oil penetrated steadily into treated leaves and, subsequently, moved to untreated petioles of the leaves and adjacent untreated stems. In another experiment, confocal laser scanning microscopy was used to visualize the penetration into, and the subsequent cellular distribution of, an nC24 agricultural mineral oil in C. trifoliata L. seedlings. Oil droplets penetrated or diffused into plants via both stomata and the cuticle of leaves and stems, and then moved within intercellular spaces and into various cells including phloem and xylem. Oil accumulated in droplets in intercellular spaces and within cells near the cell membrane. Oil entered cells without visibly damaging membranes or causing cell death. In a field experiment with mature orange trees, droplets of an nC23 horticultural mineral oil were observed, by fluorescence microscopy, in phloem sieve elements in spring flush growth produced 4-5 months and 16-17 months after the trees were sprayed with oil. These results suggest that movement of mineral oil in plants is both apoplastic via intercellular spaces and symplastic via plasmodesmata. The putative pattern of the translocation of mineral oil in plants and its relevance to oil-induced chronic phytotoxicity are discussed.
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Affiliation(s)
- B L Tan
- Centre for Horticulture and Plant Sciences, University of Western Sydney, Locked Bag 1797, Penrith South Distribution Centre, New South Wales 1797, Australia
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Affiliation(s)
- B L Tan
- Division of Obstetrics and Gynaecology, KK Women's and Children's Hospital, Singapore.
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Zheng L, Tan JAC, Tan BL, Pereira BP, Lim AYT, Lahiri A, Kumar VP. The impact of microanastomosis of the intramuscular nerve branch on the healing of a completely lacerated skeletal muscle: a histopathological analysis. Ann Acad Med Singap 2004; 33:S24-6. [PMID: 15651192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Affiliation(s)
- L Zheng
- Musculoskeletal Research Laboratories, Department of Orthopaedic Surgery, National University of Singapore, Singapore
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Abstract
Microelectronic devices for future applications demand lithographic performance that falls within the 0.10 microm region and below. Chemically amplified resists (CARs), such as the positive tone commercial UVIII resist, offer a substantial gain in sensitivity, resolution, and process efficiency in deep ultraviolet, e-beam, and X-ray lithographies. In this work, the UVIII resist is characterized for X-ray lithographic applications by studying the "deprotection" or acid generation-diffusion process of the resist under different conditions of post-exposure bake (PEB) temperature and time, and of X-ray exposure dose. The X-ray irradiation from a copper anode at a wavelength of 1.33 nm was at an intensity of 30 microW/cm2 on the resist surface. The deprotection process of the resist during PEB was accurately monitored by using Fourier transform infrared (FT-IR) spectroscopy. The infrared absorption peaks at 1151, 1369, and 2977 cm(-1) in the spectrum of the UVIII resist were found to be useful indicators for the completion of deprotection. Results of the experiments showed that the performance of UVIII could be optimized at the PEB temperature of 140 degrees C, a time of 2 min, and X-ray exposure dose of 12 mJ/cm2. The change in resist thickness after PEB was also measured. The results were confirmed by scanning electron microscopy (SEM) in which a test structure as small as 0.12 microm was obtained in a 1-microm-thick UVIII resist layer.
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Affiliation(s)
- T L Tan
- Natural Sciences Academic Group, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616.
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Abstract
This study was conducted to compare the bioavailability of two controlled-release metformin preparations (Diabetmin Retard and Glucophage Retard) and also to correlate the in vitro and in vivo data obtained with the two preparations. Twelve healthy volunteers participated in the study, conducted according to a completely randomized, two-way crossover design. The preparations were compared using area under the plasma concentration-time curve AUC0-infinity, time to reach peak plasma concentration Tmax, and peak plasma concentration Cmax, while correlation was determined between in vitro release and in vivo absorption. Diabetmin Retard demonstrated a slower rate of in vitro release, but a faster rate of in vivo absorption than Glucophage Retard. However, the in vivo absorption of both products was found to be slower than that of drug released in vitro. A satisfactory relationship could be established between the in vitro and in vivo results, but there was no rank order correlation. No statistically significant difference was observed between the two preparations in the parameters AUC0-infinity and Cmax. However, a slight but statistically significant difference was observed between the Tmax values, but it may not be therapeutically significant. Moreover, the 90% confidence interval for the ratio of the logarithmic transformed AUC0-infinity values, as well as the logarithmic transformed Cmax values, of Diabetmin Retard over those of Glucophage Retard was within the acceptance criteria of 0.80-1.25.
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Affiliation(s)
- K H Yuen
- School of Pharmaceutical Sciences, University of Science, Malaysia.
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Chia TT, Tan BL. Properties of the class of power-logistic maps. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1996; 54:5985-5991. [PMID: 9965814 DOI: 10.1103/physreve.54.5985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Tan BL, Chia TT. Unusual period doublings in the linear-logistic map. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1995; 52:6885-6888. [PMID: 9964206 DOI: 10.1103/physreve.52.6885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Tan WM, Loke WK, Tan BL, Wee A, Khor E, Goh KS. Trivalent metal ions in the prevention of calcification in glutaraldehyde treated biological tissues. Is there a chemical correlation? Biomaterials 1993; 14:1003-7. [PMID: 8286666 DOI: 10.1016/0142-9612(93)90193-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The influence of chemical factors on trivalent metal ions in the prevention of calcification of glutaraldehyde treated biological tissue has been explored. The results indicate that the chemical link lies in the hard character of the trivalent metal ions. Metal ions with the hardest character appear to have the best chance of reacting with oxygen atoms of the phosphate groups at nucleation sites of hydroxyapatite. This disrupts the nucleation and thus prevents calcification in glutaraldehyde treated biological tissue.
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Affiliation(s)
- W M Tan
- Department of Chemistry, National University of Singapore, Kent Ridge
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Tan BL, Chia TT. Properties of a logistic map with a sectional discontinuity. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1993; 47:3087-3098. [PMID: 9960362 DOI: 10.1103/physreve.47.3087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Tan BL, Cleton FJ, van Beusekom GT, Veltkamp JJ, van Rood JJ. Plasmapheresis treatment of haemorrhagic complications in a patient with multiple myeloma. Folia Med Neerl 1967; 10:174-179. [PMID: 5590976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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Tan BL, Cleton FJ. [Leukocyte transfusion]. Folia Med Neerl 1966; 9:144-7. [PMID: 5977517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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