Simulation of IRNSS Navigation Payload Operations for End to End Payload Testing

Fault free operations of space vehicles have always been a challenging task. Every space mission requires stringent qualification process on ground for qualification of the space vehicle for mission operations. This paper deals with the simulation of IRNSS navigation payload operations on ground for end to end payload testing and qualification of the payload for broadcast of IRNSS navigation parameters. IRNSS is an emerging Indian regional navigation satellite system for providing the satellite based navigation service over India and neighboring region. The system is optimally designed for its space and ground segment to provide the best in class navigation service. The space segment comprises of 7 satellites with 4 satellites in geo-synchronous orbit and 3 in geo-stationary orbit. The navigation payload on-board every IRNSS spacecraft comprises of navigation signal generation unit, atomic clocks and ranging subsystems. For every IRNSS spacecraft, a series of tests are carried out during different phases of spacecraft integration and testing. The core elements of IRNSS navigation operations such as IRNSS navigation software, payload test receiver, atomic clocks and telecommand and telemetry subsystem all participate in simulation and end to end testing of navigation payload. This paper describes in detail the simulation of various mission scenarios with respect to navigation payload operations considering different phases of satellite operations, subsystems involved and environment. The simulation has been key to successful operations of IRNSS 1A and IRNSS 1B which are operational in IRNSS space segment. Keywords: IRNSS, Navigation, payload, simulatio

A Mycobacterium leprae Hsp65 Mutant as a Candidate for Mitigating Lupus Aggravation in Mice

Hsp60 is an abundant and highly conserved family of intracellular molecules. Increased levels of this family of proteins have been observed in the extracellular compartment in chronic inflammation. Administration of M. leprae Hsp65 [WT] in [NZBxNZW]F1 mice accelerates the Systemic Lupus Erythematosus [SLE] progression whereas the point mutated K409A Hsp65 protein delays the disease. Here, the biological effects of M. leprae Hsp65 Leader pep and K409A pep synthetic peptides, which cover residues 352–371, are presented. Peptides had immunomodulatory effects similar to that observed with their respective proteins on survival and the combined administration of K409A+Leader pep or K409A pep+WT showed that the mutant forms were able to inhibit the deleterious effect of WT on mortality, indicating the neutralizing potential of the mutant molecules in SLE progression. Molecular modeling showed that replacing Lysine by Alanine affects the electrostatic potential of the 352–371 region. The number of interactions observed for WT is much higher than for Hsp65 K409A and mouse Hsp60. The immunomodulatory effects of the point-mutated protein and peptide occurred regardless of the catalytic activity. These findings may be related to the lack of effect on survival when F1 mice were inoculated with Hsp60 or K409A pep. Our findings indicate the use of point-mutated Hsp65 molecules, such as the K409A protein and its corresponding peptide, that may minimize or delay the onset of SLE, representing a new approach to the treatment of autoimmune diseases

A convergent synthesis of the C31-C46 fragment of phorboxazoles

A convergent synthesis of the C31-C46 fragment of phorboxazoles has been achieved. This involved the preparation of a C31-C39 aldehyde and a C40-C46 benzothiazole secondary - sulfone followed by their coupling, employing modified Julia ole- fination as a key reaction

New and practical synthesis of 1,4-dihydrobenzopyrano-pyrazoles

A new method for the synthesis of 1,4-dihydrobenzopyranopyrazoles using bromovinyl hydrazones has been described involving a [3+2] intramolecular cycloaddition

Direct conversion of tosylhydrazones to tert-butyl ethers under Bamford-Stevens reaction conditions

A new method for the preparation of tert-butyl ethers is described starting from aryl aldehyde and ketone tosylhydrazones under Bamford-Stevens reaction conditions (t-BuOK/t-BuOH)

A concise and stereoselective synthesis of both enantiomers of altholactone and isoaltholactone

A concise and flexible stereoselective route to synthesize both enantiomers of the highly functionalized α,β-unsaturated-δ-lactones, altholactone and isoaltholactone, from readily available cinnamyl alcohol is described. This approach derived its asymmetry from Sharpless catalytic asymmetric epoxidation and Sharpless asymmetric dihydroxylation reactions. The resulting diols were produced in high enantiomeric excess and were cyclized in a stereoselective manner in the presence of a catalytic amount of camphor sulphonic acid. The synthesis of both enantiomers of altholactone and isoaltholactone has been achieved in a concise and highly enantioselective manner