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Application of Laser-Driven Beams for Radiobiological Experiments
Published in Paul R. Bolton, Katia Parodi, Jörg Schreiber, Applications of Laser-Driven Particle Acceleration, 2018
Anna A. Friedl, Thomas E. Schmid
So far, most of the biological experiments with laser-driven particle bunches were performed with the intention of setting the stage for future applications in radiotherapy, especially radiotherapy with accelerated protons and heavier ions. For further discussion of laser-driven beam applications in radiotherapy, see Chapter 11 by Enghardt, Pawelke and Wilkens. Already early after the first description of laser-driven particle acceleration (to tens of MeV energies), its potential application for therapy was discussed [Bulanov 2002]. A variety of differences between laser-driven and conventionally2 driven particle beams was anticipated, including the exponential energy distribution and ultra-high dose rate. During the early acceleration phase at the source (i.e. laser target) single ion bunches are of tens of femtosecond duration with bunch charge adequate to deliver several Gy doses. However, due to their intrinsically large energy spread (typically characterized by an exponential energy distribution or spectrum) and commensurate debunching during transport to a biological sample or tumour site, the delivered dose rates are expected to be about 109 Gy/s or 1 Gy per nanosecond [Dollinger 2009]. Experiments using X-rays from the 1960s and 1970s suggested that at ultra-high dose rates, the cellular effects could be reduced due to depletion of intracellular oxygen. The well-known oxygen effect, i.e. enhanced radiation effects in the presence of oxygen as compared to hypoxic or anoxic conditions, is explained by higher radiation-induced production of free radicals and faster fixation of damage in the presence of oxygen. A recent literature review [Wilson 2012] delineated the conditions under which oxygen depletion may affect cellular radiation effects: for X-ray and electron irradiation at instantaneous doses rates of 109 Gy/s and higher and at single-shot delivery of sufficiently high doses (5–10 Gy), oxygen depletion can occur if the cells already have low oxygen levels. However, no data are available at present on oxygen depletion caused by other charged particles.
Combustion, performance, and emission study on the octanol- neem biodiesel blends fueled diesel engine
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Mathalai Sundaram Chandra Sekar, Vennimalai Rajan Ananthan, Nagarajan Baskaran, Hari Kishore Suresh Kumar, Rameshbabu Arumugam
At Higher temperature, diatomic nitrogen splits into monotonic and combine with oxygen and forms NO emissions. Figure 9 represents NO emissions for NBD, O10NBD90, diesel and O20NBD20.NO emissions for all fuels vary from 5.2 to 13.4 g/kWh from no to full load conditions. NO emissions are highest for NBD and lowest for diesel. Diesel produces less NO because of its negligible inbuilt oxygen content. NO emissions for O10NBD90 and O20NBD20 are lower than NBD at all BP (1.1–5.5 BMEP). NO for O10NBD90 and O20NBD20 is 0.6 and 0.9 g/kWh lower than NBD at 1.1 BP. At 5.5 BP, the NO for O10NBD90 and O20NBD20 is 1.3 and 1.7 g/kWh lower than NBD. Latent heat of octanol in O10NBD90 and O20NBD20 achieve cooling effect during combustion and lower the temperature. The oxygen effect of octanol is suppressed by the cooling effect of octanol in O10NBD90 and O20NBD20 which result in lower NO. The similar trend was identified in the investigation conducted by Yuvarajan, Venkata Ramanan, and Christopher Selvam (2016).
A preliminary approach in the prediction of orthodontic bone remodeling by coupling experiments, theory and numerical models
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Daniel George, Delphine Wagner, Yves Bolender, Pascal Laheurte, Boris Piotrowski, Paul Didier, Morad Bensidhoum, Valentin Herbert, Camille Spingarn, Yves Rémond
The mechanical force system applied onto the teeth induces a deformation of the PDL. In the compression area, the PDL vascularization is partially occluded causing a decrease in oxygen concentration which is known to increase the proliferation of osteoclasts (Utting et al. 2006). On the other hand, in the tensile zone, the oxygen concentration will increase due to PDL stretching, which is the cause of proliferation of osteoblasts (Arnett et al. 2003). These key factors are assumed to be at the origin of the bone remodeling phenomena in orthodontics. With this understanding of the PDL physiological behavior, the impact of the oxygen effect on the cells’ evolutions is highlighted (George et al. 2018). The phenomena are integrated within a second FE model (FE2) (Spingarn et al. 2018), accounting for the mechanobiological coupling between mechanical forces and cellular activation, in order to determine the initiation of the bone remodeling phenomena and tooth movements.
Influence of ethanol-gasoline blended fuel on performance and emission characteristics of the test motorcycle engine
Published in Journal of the Air & Waste Management Association, 2022
Thanh Dinh Xuan, Dien Vu Minh, Binh Pham Hoa, Khanh Nguyen Duc, Vinh Nguyen Duy
In general, when the engine operates in a rich fuel mixture, the exhaust emissions include a high concentration of CO since there is insufficient oxygen to convert all of the carbon atoms to CO2. Thus, the air-fuel equivalency ratio is the most critical CO emission parameter. Even when the engine operates in stoichiometric or lean conditions, CO emission is still generated due to the lack of oxygen in some local areas or a quick-burning process. Figure 3 illustrates the CO emission concentration fluctuations for various fuels at various vehicle speeds. The impact of ethanol concentrations on CO emissions is expected to be reduced due to oxygen enrichment resulting from ethanol. This contribution may be seen as a pre-mixed oxygen effect enhancing the reaction’s completion. Figure 3 illustrates the CO emission concentration fluctuations for various fuels at various vehicle speeds. CO emissions decreased in E0, E5, E10, and E20, respectively. It can be seen the lowest CO concentration at a speed of 25 km/h reaching the lowest value of about 11,000 ppm corresponding to E20. On average, over the entire speed range, the emission reductions of E20, E10, and E5 compared to E0 were 61%, 48%, and 39%, respectively. As a result, the amount of oxygen in ethanol-gasoline blends affects CO emissions. The presence of oxygen in these fuel mixes enhances both combustion and leaning effects in rich mixtures, lowering CO exhaust emission levels. Other experiments found comparable outcomes when CO emissions were lowered by adding alcohol to gasoline. Additionally, the drop in CO emission levels may result from ethanol’s quicker flame speed, which boosts combustion efficiency.