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Terahertz Time-Domain Spectroscopy in the Assessment of Diabetic Complications
Published in Andrey V. Dunaev, Valery V. Tuchin, Biomedical Photonics for Diabetes Research, 2023
Sviatoslav I. Gusev, Ravshanjon Kh. Nazarov, Petr S. Demchenko, Tianmiao Zhang, Olga P. Cherkasova, Mikhail K. Khodzitsky
As a result, the refractive index n of a sample in the container can be calculated. The real part of the blood refractive index is calculated as:
Particles and Radiation
Published in Rob Appleby, Graeme Burt, James Clarke, Hywel Owen, The Science and Technology of Particle Accelerators, 2020
Rob Appleby, Graeme Burt, James Clarke, Hywel Owen
For example, water has a refractive index of about 1.33 for visible wavelengths. Hence the Čerenkov angle is . Notice that Čerenkov radiation is emitted when any charge is moving through a material with , but we will only see that radiation if the material itself is transparent to it. Also, the Čerenkov radiation is emitted at 41° at any azimuth around the direction of the charge – the radiation is emitted as a cone. Slower-moving particles () give rise to a radiation cone which is narrower, and obviously the minimum velocity where Čerenkov radiation is produced is when , in other words when . In water, charged particles have to move faster than to generate Čerenkov radiation (Fig 6.30). Note that we haven't said what kind of charged particle can do this – any charge can generate Čerenkov radiation. However, usually it's electrons that we talk about since they are the most common situation.
X-ray Vision: Diagnostic X-rays and CT Scans
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
The index of refraction depends not only on the type of medium but also on the frequency of the wave traveling through the medium. This property gives rise to the phenomenon of dispersion – the separation of white light into a spectrum of colors after passing through a glass prism (Figure 3.6). The refractive index of glass, n, depends on the frequency of light. As a result, rays of different colors have different deflection angles as they exit the prism. Blue rays have the greatest angle and red rays have the smallest angle. The refractive index of soft tissues for the x-ray part of the electromagnetic spectrum is very close to unity, the value in vacuum: where δ is a small parameter that depends on the density and atomic structure of the medium. The values of δ are positive.
Observation of Cyclosporin A: Sustained Release Intraocular Lens Implantation in Rabbit Eyes
Published in Current Eye Research, 2022
He Teng, Jing Sun, Kai Wen, Guoge Han, Fang Tian
Fig. 1. A The general observation of IOL, it can be seen that the coating area is translucent and the boundary is clear. The coating is distributed in two loops of IOL. The coating surface is smooth. The diameter of IOL optical part is 6mm, the total length is 12.5mm. A constant is 118.5, and the refractive index is 1.45. Fig. B The optical part of IOL is observed under scanning electron microscope. It can be seen that its surface is smooth and flat without particle deposition. Fig. C the loop part of IOL is observed under scanning electron microscope, It can be seen that the thickness of the loop is about 350 um and the coating thickness is about 10um. Fig. D A large number of uniform pore structures can be seen on the surface and inside of the coating. The pore size is about 2 microns.
Alternatives to titanium dioxide in tablet coating
Published in Pharmaceutical Development and Technology, 2021
Juliana Radtke, Raphael Wiedey, Peter Kleinebudde
The particle size distribution of the pigments was determined by laser diffraction (Mastersizer 3000, Malvern Instruments, Malvern, UK). For this purpose, all samples were dispersed in water and measured three times using the wet-dispersion unit. The concentration of sample in water was selected in such a way that an optimal laser obscuration of 2 − 6% was guaranteed. Any agglomerates of particles were deagglomerated by ultrasound prior to each measurement. Using the corresponding software, the particle size distribution was determined from the data based on the Mie theory and given as volume distributions. The refractive index was adjusted depending on the material. For ZnO a refractive index of 2.0034 and for TiO2 of 2.493 was applied (Bodurov et al. 2016). Since the ready-to-use mixtures (APP117 and APP123) contained i.a. dibasic calcium phosphate, the refractive index of dicalcium phosphate (1.55) was applied for the respective measurements. The x10 quantile and the x50 quantile from the obtained distribution curves were used to describe the particle size. Determination was challenging for the ready-to-use mixture, since they contained further excipients like polymers and stabilizers. All other excipients except the pigments were however soluble and therefore expected not to interfere with the particle size determination. This was especially the case, since the sample was strongly diluted with water before measurement.
Lipo-PEG nano-ocular formulation successfully encapsulates hydrophilic fluconazole and traverses corneal and non-corneal path to reach posterior eye segment
Published in Journal of Drug Targeting, 2021
Shilpa Kakkar, Mandeep Singh, Sankunny Mohan Karuppayil, Jayant S. Raut, Fabrizio Giansanti, Laura Papucci, Nicola Schiavone, T. C. Nag, Nan Gao, Fu-Shin X. Yu, Mohhammad Ramzan, Indu Pal Kaur
SLNs were characterised for morphology using transmission electron microscopy ((TEM), Hitachi, Japan). Particle size (DelsaTM Nano C, Beckman Coulter, Brea, CA), drug assay/total drug content (TDC), entrapment efficiency (EE), and zeta potential of developed SLNs was also determined. Further physicochemical characterisation in terms of Fourier transform infra-red spectrometry ((FTIR), Perkin Elmer, Waltham, MA), differential scanning calorimetry ((DSC); TA Instruments, New Castle, DE), X-ray diffraction ((XRD), PANalytical, EA Almelo, Netherlands) and nuclear magnetic resonance ((NMR), Bruker, Fällanden, Switzerland), spectroscopy was also done. FTIR and XRD studies were conducted on lyophilised samples. pH, osmolarity, and refractive index ((RI) of the FCZ-SLNs was also determined as a measure of ocular comfort. RI was calculated using the formula n = c/v; where n is the refractive index of the medium, c is the velocity of light in vacuum and v is the velocity of light in the medium. Details of characterisation studies are included in the Supplementary data.