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Scintillation Fiber Optic Dosimetry
Published in Arash Darafsheh, Radiation Therapy Dosimetry: A Practical Handbook, 2021
There are two types of sources for loss in HWGs: Propagation loss and bending loss. Propagation loss varies as , where is the bore radius. Bending loss varies as , where is the bending radius [33]. HWGs based on plastic and glass tubing have been fabricated with bore diameters ∼0.1–2 mm. However, there is a tradeoff between mechanical flexibility, robustness, and throughput. Since the power loss in a HWG is inversely proportional to the cube of the bore radius, increasing the bore diameter reduces the transmission loss. However, there is a practical limit as the waveguide bore size is increased, resulting in a rigid glass rod instead of a relatively flexible HWG. In practice, the largest hollow glass waveguide size that is typically used is ∼1 mm inner diameter. HWGs made from plastic tubing are more flexible, however they have higher scattering losses due to their inherently rougher inner surface compared to HWGs made from glass tubing.
History and Sources of Essential Oil Research
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
A further approach for sorptive enrichment of volatiles from the HS of aqueous or solid samples has been described by Tienpont et al. (2000), referred to as HS sorptive extraction (HSSE). This technique implies the sorption of volatiles into PDMS that is chemically bound on the surface of a glass rod support. The device consists of a ca. 5 cm length glass rod of 2 mm diameter and at the last centimeter of 1 mm diameter. This last part is covered with PDMS chemically bound to the glass surface. HS bars with 30, 50, and 100 mg PDMS are commercially available from Gerstel GmbH, Mülheim, Germany. After thermal conditioning at 300°C for 2 h, the glass bar was introduced into the HS of a closed 20 mL HS vial containing the sample to be investigated. After sampling for 45 min, the bar was put into a glass tube for thermal desorption, which was performed with a TDS-2 thermodesorption unit (Gerstel). After desorption and cryofocusing within a PTV injector, the volatiles were transferred onto the analytical GC column. As a result, HSSE exceeded largely the sensitivity attainable with SPME. Several examples referring to the application of HSSE in HS analysis of aromatic and medicinal plants inclusive of details of the sampling procedure were described by Bicchi et al. (2000a).
Telescopes for Inner Space: Fiber Optics and Endoscopes
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
For example, consider again the interface between glass and air. If light rays coming from glass hit an interface between glass and air at angles greater than the critical angle of 42°, then the rays undergo total internal reflection. This is illustrated for a glass rod surrounded by air in Figure 2.12. Unless the rod is bent sharply, the incident angle at each bounce of the light ray is within the total reflection condition, even if the rod is curved. As a result, all of the light bounces from end to the end of the rod even when the rod is bent, a situation illustrated in Figure 2.12.
Piperine phytosomes for bioavailability enhancement of domperidone
Published in Journal of Liposome Research, 2022
Nayyer Islam, Muhammad Irfan, Talib Hussain, Maria Mushtaq, Ikram Ullah Khan, Abid Mehmood Yousaf, Muhammad Usman Ghori, Yasser Shahzad
Permeation study of phytosomes was conducted in the everted gut sac of male Wistar rat. The facts established based on DPD intestinal absorption, can be used to determine the efficiency of PPR as P-gp inhibitor. Rats were anaesthetized with chloroform, then the small intestine was removed. The isolated small intestine of the rat was washed with Tyrode buffer solution (pH 7.4) to remove wreckages and then placed in an oxygenated Tyrode buffer solution. The small segment (5 cm) of the ileum was cut and everted on the glass rod. The everted gut was clumped from one end and filled with 500 µL Tyrode buffer. Then second end of the gut was sealed and clumped, and the gut sac was placed in the test solution containing 20 µM DPD with or without 200 µM verapamil, maintained at 37 ± 0.5 °C. The samples were collected at predetermined times intervals (0, 20, 40, 60, 80 120 min) and drug permeated across the intestinal membrane was evaluated using the RP-HPLC method (LC-2010AHT, Shimadzu, Japan) (Tetyczka et al.2017). Permeability studies were conducted for pure DPD, verapamil mixed with DPD, and phytosomes loaded with DPD and PPR.
Formulation and in vitro and in vivo evaluation of surfactant-stabilized mucoadhesive nanogels for vaginal delivery of fluconazole
Published in Drug Development and Industrial Pharmacy, 2021
Fadilah Sfouq Aleanizy, Ehab I. Taha, Mounir M. Salem-Bekhit, Alaa M. J. Felimban, Saleh A. Al-Suwayeh, Fakhria A. Al-Joufi, Magdy M. Muharram, Fulwah Y. Alqahtani, Faiyaz Shakeel, Abdullah M. E. Youssof, Mohsen Bayomi, Amal E. F. Abouelela
The in vitro releases of FLZ from PF127-based formulations C-PF127, B-PF127, and A-PF127 were 12.2 ± 1.2%, 65.3 ± 3.4%, and 45.3 ± 1.7%, respectively after 8 h (Figure 3). The C-PF127 formulation had a different release profile from that of C-Ca934. The FLZ release was delayed for 4 h compared with those of all other formulations. This could be attributed to the fact that C-PF127 had the highest viscosity (6.1 ± 0.3 Pa s) of all formulations. This can be visually observed during preparation mixing with a magnetic stirrer was nearly impossible because of its viscosity, so a glass rod was used. The high viscosity value might be because C-PF127 contains PEG 600 and PF127 is a triblock copolymer consisting of a central block of PPG flanked by two hydrophilic blocks of PEG. Therefore, hydrogen bonding occurs between the PEG of the C-PF127 surfactant and the PEG of the PF127 polymer [52].
Metronidazole-loaded nanostructured lipid carriers to improve skin deposition and retention in the treatment of rosacea
Published in Drug Development and Industrial Pharmacy, 2019
Ujwala A. Shinde, Shruti J. Parmar, Shuba Easwaran
The solid lipid and liquid lipid that showed the best solubilizing potential for MTZ were investigated for miscibility at different ratios. Different ratios of lipid (5:5, 6:4, 7:3, 8:2 and 9:1) were taken in test tubes and heated on a water bath 5–7 °C above the melting point of the solid lipid. Using a glass rod, this mixture was smeared onto a glass slide and allowed to cool. After complete solidification, a dry piece of ordinary filter paper was pressed over this lipid blend and was observed for the oozing out of any oil droplets on the paper, which is an indication of the immiscibility of the solid lipid and the liquid lipid in that ratio. A binary mixture that did not exhibit oil droplets on the filter paper was selected for use in the fabrication of NLCs.