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Deaths Due to Asphyxiant Gases
Published in Sudhir K. Gupta, Forensic Pathology of Asphyxial Deaths, 2022
Naturally, CO2 is produced as a result of respiration process and is also found in atmospheric air. Various metals like aluminum, magnesium when suspended in CO2, ignite and sometimes explode. In the atmosphere, CO2 gets accumulated in the bottom of any closed space and displace much of the oxygen as it is heavier than air (molecular weight of CO2 being 44). As CO2 is odorless and non-irritant, it usually causes silent asphyxia.2 When the gas is compressed at constant room temperature, it will eventually condense to liquid form. The liquid form is more compact than the gas form of CO2 and thus it can be transported and stored in metal cylinders at normal room temperature.3 The solid form, also known as dry ice, is made by liquefying CO2 and transferring it into a container, where it is frozen at a temperature of −109° F and compressed into solid ice. Dry ice is widely used to bring special fog effect in various public activities. It gets converted from solid to gaseous form by a process known as sublimation.
Spray Drying and Pharmaceutical Applications
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
Metin Çelik, Pavan Muttil, Gülşilan Binzet, Susan C. Wendell
A second variation of the spray drying process is spray freeze-drying. In this process, the feed is sprayed into freezing air causing the droplets to freeze. The frozen droplets are subsequently sublimed under vacuum conditions producing a dry product. One study investigated this method further by eliminating the use of vacuum conditions for sublimation [131]. In this study, the feasibility of spraying pharmaceutical solutions at atmospheric pressure was investigated using very low air temperatures and desiccated air for the removal of the water from the frozen particles. The process resulted in fine, free-flowing powder with high surface area, good wetting, and good solubility characteristics.
The Instincts as the Subject, Mechanism, and Means of Education
Published in L.S. Vygotsky, V.V. Davydov, Silverman Robert, Educational Psychology, 2020
Next is the question of the particular techniques to achieve sublimation. It should be clear to the reader that techniques of moral suasion, and even the various methods of inculcating sex information, are powerless to counter any sort of powerful centers of excitation that might arise in connection with sexual activity. Against these centers it is necessary to oppose centers that are just as powerful and that act just as constantly. This may be achieved not by isolating sex education as something special, but only through the construction of a systematic framework that would be in accord with the vital concerns of youth, and that could be thought of as a system of highly coordinated “diversion cuts” that would accommodate sublimated sexual energy and give to it an appropriate direction. The goal of sex education is also to construct these channels, and this goal must, consequently, be achieved somewhat apart from all questions of sex.
Recent advances in freeze-drying: variables, cycle optimization, and innovative techniques
Published in Pharmaceutical Development and Technology, 2022
Mohammed M. Mehanna, Kawthar K. Abla
FD also requires intensive efforts during product development compared to liquid preparations, particularly, during the scale-up stage. Features of bench equipment are not necessarily equivalent to the commercial-production freeze-driers. Moreover, traditional lyophilization has numerous limitations due to the batch-to-batch or vial-to-vial end products variability. Thus, the aforementioned quality of attributes may vary according to the location of the vial within the chamber. Thus, controlling ice nucleation and the use of advanced lyophilizer as pilot scale freeze-drier, have been adopted to control the lyophilization cycle. Pilot scale up is a hygienic bulk lyophilizer with an external condenser that can be separated from the drying chamber. The sublimation process is performed using electrical heating systems. This resulting in a uniform temperature gradient and pressure throughout the entire tray surface area maintaining the product quality.
Spray freeze-drying for inhalation application: process and formulation variables
Published in Pharmaceutical Development and Technology, 2022
Mostafa Rostamnezhad, Hossein Jafari, Farzad Moradikhah, Sara Bahrainian, Homa Faghihi, Reza Khalvati, Reza Bafkary, Alireza Vatanara
After completion of the spray freezing, the frozen particles are separated by the sieve, or after evaporation of the cryogenic agent, they can be separated. This process most typically continues with conventional FD, especially in the SFL in which the use of conventional FD is frequent. Then, collected frozen droplets are transferred to cool chambers in a lyophilizer (less than −40 °C). Principles for sublimation are similar to traditional FD. Ice-sublimation occurs below the triple point of water, i.e. at 4.579 mmHg and 0.0099 °C (like other types of solvent can be used in FD, and the triple point can be different). This step is called the primary drying, usually done at low pressure and 2–5 °C below the product collapse temperature (Tc), to preserve the elegant shape of the resultant cake by preventing collapsing (Gad and Chengelis 1988). At the end of this step, 70–80% of the water is removed (the rest is in the amorphous matrix). There may be an annealing step before primary drying which the frozen sample is between glass transition temperature (Tg) and melting temperature for a while. Primary drying can be performed at a higher temperature and for a shorter time. An annealing step (at 0 °C for 2 h) before primary drying was shown to reduce the moisture absorption by trehalose (Sonner et al. 2002).
Molecular tissue profiling by MALDI imaging: recent progress and applications in cancer research
Published in Critical Reviews in Clinical Laboratory Sciences, 2021
Pey Yee Lee, Yeelon Yeoh, Nursyazwani Omar, Yuh-Fen Pung, Lay Cheng Lim, Teck Yew Low
Typical matrix application methods include (i) direct spray, (ii) micro-spotting, and (iii) sublimation (Table 3) [59]. Manual spraying using aerosol sprayer or airbrush is relatively low-cost, but it requires technical skill and is prone to variation. To ensure homogeneity and reproducibility, automated matrix sprayers such as SunCollect (SunChrom, Friedrichsdorf, Germany), ImagePrep (Bruker Daltonics, Bremen, Germany) and TM-Sprayer (HTX Technologies, Chapel Hill, NC) are employed for applying matrix [60]. Furthermore, the devices can also be utilized to spray enzyme solutions for on-tissue digestion. With micro-spotting, matrix droplets are deposited on defined spots on the tissue. Commercial systems including CHIP-1000 chemical inkjet printer (Shimadzu, Manchester, UK) and Portrait (Labcyte, Sunnyvale, CA) can provide uniform coating of matrix and enzyme solutions, albeit in lower spatial resolution due to the larger size of the matrix droplet [61]. The sublimation method is a solvent-free matrix application technique that is performed under reduced pressure and elevated temperature. It prevents analyte diffusion and provides high spatial resolution for lipids and metabolites [62]. However, it is suitable only for certain matrices and the absence of solvent results in lower extraction efficiency for proteins and peptides.