China
Africa
Explore chapters and articles related to this topic
Analysis of Essential Oils
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Adriana Arigò, Mariosimone Zoccali, Danilo Sciarrone, Peter Q. Tranchida, Paola Dugo, Luigi Mondello
The measurement of optical rotation, [α]D20, either dextrorotatory or laevorotatory, is also widely recognized. Optical activity is determined by using a polarimeter, with the angle of rotation depending on a series of parameters, such as oil nature, the length of the column through which the light passes, the applied wavelength, and the temperature. The degree and direction of rotation are of great importance for purity assessments, since they are related to the structures and the concentration of chiral molecules in the sample. Each optically active substance has its own specific rotation, as defined in Biot's law: where α is the optical rotation at a temperature T expressed in degrees Celsius, l is the optical path length in dm, λ is the wavelength, and c is the concentration in g/100 mL. It is worthy of note that a standard 100 mm tube is commonly used; in cases in which darker or lighter colored oils are analyzed, longer or shorter tubes are used, respectively, and the rotation should be extrapolated for a 100 mm-long tube. Moreover, prior to the measurement, the essential oil should be dried out with anhydrous sodium sulfate and filtered.
Laser microscopy of polycrystalline human blood plasma films
Published in Waldemar Wójcik, Sergii Pavlov, Maksat Kalimoldayev, Information Technology in Medical Diagnostics II, 2019
O.V. Dubolazov, A.G. Ushenko, Y.A. Ushenko, M.Yu. Sakhnovskiy, P.M. Grygoryshyn, N. Pavlyukovich, O.V. Pavlyukovich, S.V. Pavlov, V.D. Mishalov, C. Kaczmarek, A. Kalizhanova
Figure 1 shows the traditional optical scheme of a polarimeter (Ushenko & Pishak 2004). The illumination of blood plasma samples was carried out in parallel low-intensity (P = 5,0 mW) beam from a He-Ne laser (λ = 0.6328 µm). The polarisation illuminator consists of quarter-wave plates 3, 5 and a polariser 4, which ensures the formation of a laser beam with arbitrary azimuth and polarisation ellipticity. Images of blood plasma with a micro-lens 7 were projected into the plane of the photosensitive pad CCD-camera 10. The analysis of images of human blood plasma was carried out with the help of a polariser 9 and a quarter-wave plate 8.
Noninvasive glucose monitoring
Published in Moshe Hod, Lois G. Jovanovic, Gian Carlo Di Renzo, Alberto de Leiva, Oded Langer, Textbook of Diabetes and Pregnancy, 2018
When polarized light hits certain molecules, it rotates. These molecules are called optically active and they can be detected using polarimetry. Using a dual-wavelength optical polarimeter, this technique was studied48 in 2012 on nine rabbits employing a contact lens and an external light source, measuring the glucose level within the aqueous humor. Accuracy was very good with 100% of the results falling within areas A+B on the Clarke EGA. These data are still preliminary, and many adaptations will be needed for human subjects as an external light source must be placed directly on the eyelid, causing discomfort and also limiting the continuity of measurement.
Inhibition of Streptococcus mutans adhesion and biofilm formation with small-molecule inhibitors of sortase A from Juniperus chinensis
Published in Journal of Oral Microbiology, 2022
Eunji Cho, Ji-Yeon Hwang, Jae Sung Park, Daehyun Oh, Dong-Chan Oh, Hyeung-Geun Park, Jongheon Shin, Ki-Bong Oh
Optical rotation was measured with a JASCO P-2000 polarimeter (Easton, MD) with a 1-cm cell. Ultraviolet (UV) spectra were acquired using a Hitachi U-3010 spectrophotometer (Tokyo, Japan). Infrared (IR) spectra were obtained with a JASCO 4200 FT-IR spectrometer (Easton, MD) using a ZnSe cell. High-resolution electrospray ionization mass spectrometry (HR-ESI-MS) data were acquired at the National Instrumentation Center for Environmental Management (Seoul, Korea) using an AB Sciex 5600 QTOF HR-MS instrument (Sciex, MA). Proton and carbon nuclear magnetic resonance spectroscopy (NMR) and two-dimensional NMR spectra were recorded with a Varian Gemini 2000 300 MHz spectrometer (Palo Alto, CA) or Bruker Avance 500 and 600 MHz spectrometers (Berlin, Germany) using MeOH-d4 with a solvent peak at δH 3.31/δC 49.0 or dimethyl sulfoxide (DMSO)-d6 with a solvent peak at δH 2.50/δC 39.50 as internal standards. High-performance liquid chromatography (HPLC) separation was conducted on a SpectraSYSTEM p2000 instrument equipped with a refractive index detector (SpectraSYSTEM RI-150) and a UV-Vis detector (UV-Vis-151, Gilson, Middleton, WI). All solvents used were of spectroscopic grade or were distilled prior to use.
Natural polyketide 6-pentyl-2H-pyrone-2-one and its synthetic analogues efficiently prevent marine biofouling
Published in Biofouling, 2021
Mo Aqib Raza Khan, Bo-Wei Wang, Yih-Yu Chen, Ting-Hsuan Lin, Hsiu-Chin Lin, Yu-Liang Yang, Ka-Lai Pang, Chih-Chuang Liaw
Sephadex LH-20 (Amersham Pharmacia Biotech AB,Uppsala, Sweden) was used for primary separation. The high performance liquid chromatography (HPLC) system consisted of a Hitachi L-2310 series pump (Hitachi, Tokyo, Japan), an L-2420 UV-VIS detector (Hitachi), and a reversed-phase C18 column (5 µm, 250 × 10 mm, Discovery® HS C18, Supelco Park, Bellefonte, PA, USA). Structural elucidation of α-pyrones was achieved using analytical and spectrometric strategies. The Varian 400 NMR instrument was used to record 1H NMR and 13C NMR spectra. The chemical shifts in the spectroscopic data are given in δ (ppm) and coupling constants are shown in hertz (Hz). A Bruker amaZon SL mass spectrometer equipped with an electrospray ionization (ESI) source (Bruker, Bremen, Germany) was used for acquiring mass data. Optical rotations (OR) were obtained on JASCO P-2000 polarimeter (Tokyo, Japan). Ultra-violet (UV) spectra were recorded on JASCO V-530 UV/VIS spectrophotometer. Infrared (IR) spectra were obtained by using JASCO FTIR-4000 FTIR spectrophotometer.
Cytotoxic compounds from the leaves and stems of the endemic Thai plant Mitrephora sirikitiae
Published in Pharmaceutical Biology, 2020
Natthinee Anantachoke, Duangporn Lovacharaporn, Vichai Reutrakul, Sylvie Michel, Thomas Gaslonde, Pawinee Piyachaturawat, Kanoknetr Suksen, Samran Prabpai, Narong Nuntasaen
The melting points were determined on a digital Electrothermal 9100. Optical rotations were measured with a JASCO DIP-370 digital polarimeter in a 50 mm microcell (1 mL). Ultraviolet and infra-red spectra were recorded using Shimadzu UV-2600 and Alpha Bruker spectrophotometers, respectively. Electron ionisation mass spectrometry (EI-MS) and high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) data were obtained on Thermo Finnigan Polaris Q and Micromass VQ-TOF2 spectrometers, respectively. 1H-NMR (400, 500 MHz), 13C-NMR (100, 125 MHz), and 2 D correlation spectra were recorded on Bruker Avance 500 and Bruker Ascend 400 NMR spectrometers in CDCl3, CD3OD, or C5D5N. Separation was achieved using silica gel P60 40–63 µm (SiliaFlash®; Silicycle), reversed phase silica gel C-18, 40–63 µm (Silicycle), and Sephadex™ LH-20 (GE Healthcare Life Sciences) as stationary phases for column chromatography and silica gel 60 F254 for preparative thin layer chromatography (PTLC, 20 × 20 cm, layer thickness 1 mm; Merck). Silica gel 60 PF254 (layer thickness 0.2 mm; Merck) TLC plates were used for analytical TLC. The TLC plates were detected by exposure to ultraviolet (UV) light at 254 and 366 nm and spraying with 30% H2SO4 in methanol, 1% CeSO4 in 10% aqueous H2SO4, or Dragendorff’s reagent.