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Instrumentation for Assessing mTBI Events
Published in Mark A. Mentzer, Mild Traumatic Brain Injury, 2020
Once the deformation is read from the kinetics spectrum, several quantities may be extracted, which can be used to further characterize different candidate materials. These parameters are illustrated in Figure 3.7. The principle used is the Beer–Lambert law, which is normally used to determine the concentration dependence C of a solute in a solvent from absorbance data A: A = εlC, where l is path length and ε is the extinction coefficient or molar absorptivity. In our case all material parameters may be assumed fixed, with the path length l being replaced by mass m due to delamination. Thus, the transmittance T is proportional to the variation ion path length or, equivalently, the mass change. Therefore a priori measurement of T(t) versus known m can be used to compute the change of mass: T(t) = εmρ where ρ is the density and t is the observation time.
Screening Smokes: Applications, Toxicology, Clinical Considerations, and Medical Management *
Published in Brian J. Lukey, James A. Romano, Salem Harry, Chemical Warfare Agents, 2019
Lawrence A. Bickford, Harry Salem
A high-performing obscurant is one that is most efficient at blocking light or radiation at wavelengths of interest. When this reduced transmittance through a cloud reaches a critical level, then the eyeball or sensor cannot accurately distinguish background from target. According to Beer’s law, there are several factors that affect transmittance: path length through the cloud, the concentration in the cloud, and the extinction coefficient. Transmittance and extinction coefficient vary as a function of wavelength. Extinction is defined in terms of the beam attenuation of electromagnetic radiation due to scattering and absorption as it traverses a medium (Bohren and Huffman, 2004). The extinction coefficient, α, is related to the beam transmittance T through an aerosol cloud by
Eyesight standards for beach lifeguards
Published in Mike Tipton, Adam Wooler, The Science of Beach Lifeguarding, 2018
Another important characteristic of sunglasses which needs to be considered is their ability to transmit light. Their transmittance should be such that only frequencies that are not detrimental to the eyes and vision are allowed to penetrate. Thus, in addition to filtering unwanted frequencies, sunglasses should also reduce the percentage of the light they allow to penetrate. Transmittance is defined in terms of percentage of the total light available after filtration. Again, there are no extensive or specific studies on this topic relevant to beach lifeguarding. From one study conducted on US Army sunglasses, it would appear that a sun-glass transmittance of 23% results in a minimal decrease in visual performance relative to normal clinical test conditions.
Effect of formula factors on the properties of HPMC plant hollow capsule film
Published in Drug Development and Industrial Pharmacy, 2021
Huipu Ding, Shulei He, Wenqin Luo, Liping Liu, Sa Wang, Xuhan Chen
As shown in Figure 5, as the concentrations of HPMC, carrageenan, potassium chloride, and Tween 80 increase, the light transmittance of the capsule film gradually decreases. This is similar to the study of Zhang et al. [27]. The reason maybe that from the perspective of the quantity and concentration of the dispersed phase, at low concentrations, the effect of quantity and concentration on the optical properties of the substance dominates. Therefore, as the concentration of the four substances increases, the transmittance of the film decreases significantly. Referring to the 2020 edition of the Chinese Pharmacopoeia’s light transmittance standards and literature for capsule gelatin, the various capsule films in this experiment have a light transmittance of more than 85% at 450 nm, 500 nm, or 620 nm, and have good light transmittance [28].
Development and optimization of drug-loaded nanoemulsion system by phase inversion temperature (PIT) method using Box–Behnken design
Published in Drug Development and Industrial Pharmacy, 2021
Manish Kumar, Ram Singh Bishnoi, Ajay Kumar Shukla, Chandra Prakash Jain
The effect of droplet size and refractive index on percentage transmittance was studied by drawing the main effects plot, and surface plot. As shown in Figure 6, an increase in droplets size of the nanoemulsion system decreases the percentage transmittance because bigger droplets have high light scattering efficiency that leads to a decrease in percentage transmittance. On the other hand, increasing the refractive index, increase the percentage transmittance. Response surface plots (Figure 7) between average droplet size, refractive index and percentage transmittance were also showed similar results. At the higher droplet size (around 150 nm), when the refractive index is high (around 1.380), percentage transmittance (transparency) was higher as compared to when the refractive index is less (around 1.350). This indicated that the transparency of the nanoemulsion system was controlled by the refractive index of the two liquid phases. When the refractive index of the aqueous phase of nanoemulsion is increased, the refractive index of both the phases (oil phase and aqueous phase) becomes similar which diminishes the refraction and the system appears transparent [36].
Possibilities of the microemulsion use as indomethacin solubilizer and its effect on in vitro and ex vivo drug permeation from dermal gels in comparison with transcutol®
Published in Drug Development and Industrial Pharmacy, 2020
Miroslava Špaglová, Mária Čuchorová, Veronika Šimunková, Desana Matúšová, Martina Čierna, Lenka Starýchová, Katarína Bauerová
Applying of the stress during centrifugation had no visual influence on structure of the MEs. By visual inspection, there was no change remarked in their appearance or an evidence of phase separation neither in MEA nor MEB. Transmittance (T) describes the quantity of light passing through a sample without its absorption [28]. Comparing to water (100% T), MEA was of lower T0 (99.0%) but little inconvenient, 3 months after storage at room temperature T was increased to 99.7%. MEB showed T0 = 99.3% and during storage it was only slightly decreased (99.2%). At storage temperature 4 ± 2 °C no change in T was recorded. The change in droplet size of MÉs inner phase was also minimal at both storage temperatures: (a) at 4 ± 2 °C in MEA an increase from 127.6 to 132.4 nm, in MEB from 153.2 to 160.1 nm; (b) at 21 ± 2 °C in MEA an increase from 127.6 to 129.6 nm, in MEB from 153.2 to 157.0 nm. The results confirmed the stability of both ME systems.