Vikram Sarabhai Space Centre

About: Vikram Sarabhai Space Centre is a facility organization based out in Thiruvananthapuram, India. It is known for research contribution in the topics: Aerosol & Ultimate tensile strength. The organization has 2092 authors who have published 3058 publications receiving 47975 citations. The organization is also known as: VSSC.

Radiative forcing by aerosols over the Bay of Bengal region derived from shipborne, island‐based, and satellite (Moderate‐Resolution Imaging Spectroradiometer) observations

Abstract: Measurements of spectral aerosol optical depths (AODs) were made over the Bay of Bengal region (adjacent to the Indian landmass) on board the oceanographic research vessel Sagar Kanya during February 2003 Simultaneous measurements of spectral AODs and mass concentrations of the composite aerosols and aerosol black carbon (BC) were made at an island location, Port Blair (1163degreesN, 9271degreesE), also in the Bay of Bengal At the cruise locations the AODs were in the range of similar to03-06 at 500 nm (with a mean value of 041 +/- 014) and Angstrom wavelength exponent of similar to11 +/- 01; while at Port Blair the AODs were in the range of 011-048 at 500 nm and Angstrom wavelength exponent of 098 +/- 007 Aerosol BC constituted 58 +/- 06% of the composite aerosol mass concentration with a single-scattering albedo of similar to088, indicating the presence of a significant amount of submicron absorbing aerosols Comparisons of AODs measured at Port Blair during cruise 188 and an earlier cruise (cruise 161B) during March 2001 (over the Bay of Bengal, Arabian Sea, and Indian Ocean) with those derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) (on board the TERRA platform) showed excellent agreement with a mean difference of similar to001 and a root-mean-square difference of similar to003 Regionally averaged aerosol (net) forcing over the Bay of Bengal was in the range -15 to -24 W m(-2) at the surface and -2 to -4 W m(-2) at the top of the atmosphere in February 2003; these values were smaller in magnitude than those observed over this region during March 2001 and larger than that observed over the Arabian Sea and the Indian Ocean The resulting atmospheric heating due to aerosol absorption was similar to05degreesK/d

New method for evaluation of kinetic parameters and mechanism of degradation from pyrolysis–GC studies: Thermal degradation of polydimethylsiloxanes

Abstract: Thermal degradation of polydimethylsiloxane (PDMS) polymers having hydroxyl (PS) and vinyl (PS-V) terminals was studied by pyrolysis-gas chromatography (PGC) in the temperature range from 550 to 950°C. The degradation products were primarily cyclic oligomers ranging from trimer (D3) to cyclomer D11 and minor amounts of linear products and methane. The product composition varied significantly with pyrolysis temperature and extent of degradation. A new method was developed to derive a mass loss-temperature curve (pyrothermogram, PTG) and to determine the kinetic parameters of decomposition (k, n, and Ea) from sequential pyrolysis studies. It was shown that isothermal rate constants can be derived from repeated pyrolysis data. Good agreement between the rate constants derived from the two methods validates the methodology adopted. This was further confirmed from thermogravimetric studies. The Ea values for the decomposition of PS and PS-V derived from sequential pyrolysis were 40 ± 2 and 46 ± 2 kcal mol−1, respectively. Various mechanisms for the degradation of PDMS were reviewed and discussed in relation to the PGC results. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 441–450, 1999