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Neuroinflammation and cognition across psychiatric conditions
- Célia Fourrier, Gaurav Singhal, Bernhard T. Baune
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- Journal:
- CNS Spectrums / Volume 24 / Issue 1 / February 2019
- Published online by Cambridge University Press:
- 04 February 2019, pp. 4-15
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Cognitive impairments reported across psychiatric conditions (ie, major depressive disorder, bipolar disorder, schizophrenia, and posttraumatic stress disorder) strongly impair the quality of life of patients and the recovery of those conditions. There is therefore a great need for consideration for cognitive dysfunction in the management of psychiatric disorders. The redundant pattern of cognitive impairments across such conditions suggests possible shared mechanisms potentially leading to their development. Here, we review for the first time the possible role of inflammation in cognitive dysfunctions across psychiatric disorders. Raised inflammatory processes (microglia activation and elevated cytokine levels) across diagnoses could therefore disrupt neurobiological mechanisms regulating cognition, including Hebbian and homeostatic plasticity, neurogenesis, neurotrophic factor, the HPA axis, and the kynurenine pathway. This redundant association between elevated inflammation and cognitive alterations across psychiatric disorders hence suggests that a cross-disorder approach using pharmacological and nonpharmacological (ie, physical activity and nutrition) anti-inflammatory/immunomodulatory strategies should be considered in the management of cognition in psychiatry.
8 - Optical Diagnostics of Singlet Oxygen for Chemical Oxygen–Iodine Laser
- Man Mohan, Emeritus Professor, Department of Physics and Astrophysics, University of Delhi, Delhi, Anil Kumar Maini, Former Director, Laser Science and Technology Centre, Delhi, Aranya B. Bhattacherjee, Associate Professor, Department of Physics, ARSD College, University of Delhi, Delhi
- Edited by Anil K. Razdan
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- Book:
- Advances in Laser Physics and Technology
- Published by:
- Foundation Books
- Published online:
- 13 July 2022
- Print publication:
- 01 January 2014, pp 120-134
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Summary
Introduction
Chemical oxygen−iodine laser (COIL) was first demonstrated by McDermott et al. in 1978 and is the only chemical laser based on electronic transition. It operates on 2P1/2 → 2P3/2 transition of iodine atom at 1.315 μm and is pumped by the following reaction scheme,
This laser due to its short wavelength, high efficiency and scalability has found application in various military and civilian scenarios in the last decade. The possibility of carrying high power beams via optical fibers makes it extremely useful for decommissioning and dismantling dangerous structures such as obsolete nuclear reactors through remotely operated mechanisms by Tei et al.
The pumping source, O2(1) is an excited form of oxygen molecule with energy level very close to that of atomic iodine enabling near resonant energy transfer as shown in Fig. 8.1. Although, different techniques such as chemical, RF discharge, photo-sensitizer, have been reported for the production of O2(1), the chemical method is the only one till date that has been successful for scaling up power. Therefore, amongst the variousmechanisms studied for the production of O2(1), the chemical method still remains at the forefront for the development of large-scale COIL systems. The chemical method is based on chemical reactions between chlorine gas and basic hydrogen per-oxide (BHP) solution resulting in production of singlet oxygen, which in turn dissociates iodine molecules into iodine atoms and also subsequently excites these atoms.
For an efficient production of singlet oxygen, jet type singlet oxygen generator (JSOG) by Rajesh et al. has proved its potential over the other techniques such as rotating disc or bubbler type. Other forthcoming generators such as twisted aerosol and centrifugal bubble/ flow type are yet to be proven for large-scale power levels.
Figure 8.2 shows the functional block diagram of chemical oxygen iodine laser[3, 9] which exhibits coupling of all subsystems. BHP solution is prepared in a separate preparation tank and supplied to the SOG reaction chamber in the form of jets. Chlorine is supplied to the SOG reaction chamber from the bottom in a counter-flow direction to the jets so that it reacts at the surface of the liquid jets to produce singlet oxygen molecules.
18 - Development of Laser Cavity and Resonator for High Power Chemical Oxygen Iodine Laser (COIL)
- Man Mohan, Emeritus Professor, Department of Physics and Astrophysics, University of Delhi, Delhi, Anil Kumar Maini, Former Director, Laser Science and Technology Centre, Delhi, Aranya B. Bhattacherjee, Associate Professor, Department of Physics, ARSD College, University of Delhi, Delhi
- Edited by Anil K. Razdan
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- Book:
- Advances in Laser Physics and Technology
- Published by:
- Foundation Books
- Published online:
- 13 July 2022
- Print publication:
- 01 January 2014, pp 278-290
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Summary
Introduction
COIL is a chemical laser in which the required pumping energy for population inversion is released via a chemical reaction. This property makes the COIL attractive for defence application because it eliminates the need for electrical power supply at remote locations. Among other chemical lasers, COIL has the advantages of power scalability, short wavelength (1.315 μm) compatible with fiber (Grunewald et al.) for remote operation and also better laser material interaction.
In COIL, a gas−liquid phase reaction between basic hydrogen peroxide and chlorine gas at sub-atmospheric pressure (Azyazov et al.) produces the pumping source, singlet oxygen. This is diluted with sufficient nitrogen buffer gas to reduce the various loss mechanisms. Part of the pump energy contained in the singlet oxygen is used in the dissociation of iodine molecules into iodine atoms and the rest is used to excite these iodine atoms by near resonant energy transfer reaction. The interaction of singlet oxygen with atomic iodine at appropriate flow conditions results in the generation of laser gain medium inside the laser cavity from where the laser output power is extracted using an optical resonator.
To develop a high power COIL, it is important to study the gain characteristics, i.e., the small signal gain and the saturation intensity of the active medium under different flow conditions and to evaluate the optimum cavity coupling for achieving maximum output power. In this chapter, different COIL input parameters required for optimal gain medium formation in the laser cavity have been analyzed and gain characteristics using simplified saturation model (SSM) (Hager et al.) for the development of high power COIL have been estimated. The resonator parameters and output mirror coupling are evaluated keeping in view the resonator stability, diffraction loss, utilization of mode volume and laser beam divergence. On the basis of these parameters, the laser cavity and optical resonator for high power COIL have been developed and tested.
COIL gain medium formation