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Deaths Due to Asphyxiant Gases
Published in Sudhir K. Gupta, Forensic Pathology of Asphyxial Deaths, 2022
Other sewer gases include carbon dioxide and methane which have little or no odor characteristics and have a saturated gas density approximately 1.5 and 0.6 times that of air, respectively. Methane is extremely flammable, has a wide explosive range, and a low flash point. These characteristics result in a substantial fire and explosion hazard. Ammonia has a distinct, strong odor with good warning characteristics which are present well before attaining toxic levels.
Basics of Radiation Interactions in Matter
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
where is the mass density of matter. A complete quantum mechanical expression is provided by the Bethe–Bloch formula:
Fundamentals of Radiation Physics and Dosimetry
Published in Arash Darafsheh, Radiation Therapy Dosimetry: A Practical Handbook, 2021
Blake R. Smith, Larry A. DeWerd
There are four primary photon–electron interactions that our discussion of dose is concerned with and they are Rayleigh, photoelectric, Compton, and pair and triplet production interactions. However, only the latter three emit charged particles after the interaction takes place and dominate within the ranges of photon energies encountered in the practice of medical physics. Each of these interactions contributes to a loss of incident photon fluence through a medium. The occurrence of an interaction taking place can be thought of as a dart hitting a binary dart board – either the dart hits the bull's eye or it misses. The probability that the bull's eye is hit is related to the size of the dart and the size of the bull's eye relative to the dart board. This is analogous to a fluence of uncharged radiation, (cm−2), of particles incident upon a slab of matter composed of many potential atomic “targets” each with a little cross-sectional area, (cm2). The number of targets within a unit volume of the matter can be estimated as from the mass density, , and mass number of the substance, . The rate that the initial fluence reduces in depth due to the number of interactions that occur is
Effect of ventilation mode and airflow rate on the flow field and particle mass concentration distribution of a high-speed rail carriage in the putty polishing workshop
Published in International Journal of Occupational Safety and Ergonomics, 2023
Pei Wang, Bin Yang, Jie Wang, Jieqiong Zhou, Jianwu Chen
The airflow–particle field in the polishing workshop is basically a gas–solid two-phase flow. Because the volume fraction of putty particles in the workshop is less than 10%, the impact of particles on the fluid can be negligible [23]. Because the Reynolds stress model (RSM) considers the effects of streamline curvature, vortices, rotation and rapid change of strain rate in a more rigorous manner than single-equation and two-equation models, it can give accurate prediction results for complex flows [24–28]. The mathematical models are as follows: i, j and k = three directions in the Cartesian coordinate system; = velocity fluctuations, respectively; = diffusion term; = pressure strain term; = production term; = dissipation term; = user-defined source term; t = gas motion time; ρ = gas density; x = gas motion distance; U = gas velocity; δ = diffusion coefficient; p = gas pressure; μ = gas dynamic viscosity.
A novel ligand-modified nanocomposite microparticles improved efficiency of quercetin and paclitaxel delivery in the non-small cell lung cancer
Published in Drug Delivery, 2022
Xiaoming Cui, Fang Zhang, Yanyan Zhao, Pan Li, Ting Wang, Zhilu Xu, Jingjing Zhang, Weifen Zhang
The particle size and Zeta potential of P/Q@NMPs and P/Q@CNMPs were determined through the dynamic light scattering (DLS) measurements with a Malvern Nano-ZS 90 instrument (Malvern Pana transmission electron microscopy lyrical, Westborough, MA, USA). The morphology was observed by transmission electron microscopy (TEM, JEM-1230; JEOL, Tokyo, Japan) and scanning electron microscopy (SEM, Hitachi High-Tech Science Corporation, Tokyo, Japan). Aerodynamic diameter (daer) was also determined by placing 0.5 g samples in the pycnometer (5 mL) and dropped in the air at a frequency of 30 times/min (height of about 14 cm) until the powder volume in the pycnometer was no change be observed (n = 3). The drug loading (DL) and encapsulate efficiency (EE) were determined by Ultraviolet (UV). The DL, EE, and aerodynamic diameter (daer) were calculated according to the following equations: l is the determined weight of the drug in MPs, Wf is the total weight of the drug-loaded MPs, and Dt is the total weight of the number of drugs added. daer is the aerodynamic diameter of MPs, d is the geometric particle size of MPs, ρ is the tapped density of MPs, and ρ1 is the water mass density (ρ1=1 g/cm3). Each experiment was repeated thrice independently.
Computer simulations of an irrigated radiofrequency cardiac ablation catheter and experimental validation by infrared imaging
Published in International Journal of Hyperthermia, 2021
Christian Rossmann, Anjan Motamarry, Dorin Panescu, Dieter Haemmerich
The heat transfer problem was solved in the blood, tissue, and catheter domains; heat transfer by convection and conduction were considered in the fluid domain, and heat transfer by conduction alone in the solid domains. The temperature field was assumed to be continuous between the fluid and solid domains. Joule heating was active in all domains. The following heat transfer equation (22) was solved (with u = 0 in solid domains): QRF on the right-hand side represents the term for the heat source due to RF heating (Equation 2). T (°C) denotes the tissue temperature, C (J/(kg °C)) is the tissue heat capacity, k (W/(m °C)) indicates the tissue thermal conductivity, and ρ (kg/m3) is the tissue mass density.