Room temperature magnetic entropy change and magnetoresistance in La_{0.70}(Ca_{0.30-x}Sr_x)MnO_3:Ag 10% (x = 0.0-0.10)

The magnetic and magnetocaloric properties of polycrystalline La0.70(Ca0.30-xSrx)MnO3:Ag 10% manganite have been investigated. All the compositions are crystallized in single phase orthorhombic Pbnm space group. Both, the Insulator-Metal transition temperature (TIM) and Curie temperature (Tc) are observed at 298 K for x = 0.10 composition. Though both TIM and Tc are nearly unchanged with Ag addition, the MR is slightly improved. The MR at 300 K is found to be as large as 31% with magnetic field change of 1Tesla, whereas it reaches up to 49% at magnetic field of 3Tesla for La0.70Ca0.20Sr0.10MnO3:Ag0.10 sample. The maximum entropy change (\DeltaSMmax) is 7.6 J.Kg-1.K-1 upon the magnetic field change of 5Tesla, near its Tc (300.5 K). The La0.70Ca0.20Sr0.10MnO3:Ag0.10 sample having good MR (31%1Tesla, 49%3Tesla) and reasonable change in magnetic entropy (7.6 J.Kg-1.K-1, 5 Tesla) at 300 K can be a potential magnetic refrigerant material at ambient temperatures.Comment: 11 pages text + Figs comments/suggestions ([email protected]

Synthesis of Oligodeoxyribo‐ and Oligoribonucleotides According to the H‐Phosphonate Method

Oligonucleotides can be synthesized by condensing a protected nucleoside H‐phosphonate monoester with a second nucleoside in the presence of a coupling agent to produce a dinucleoside H‐phosphonate diester. This can then be converted to a dinucleoside phosphate or to a backbone‐modified analog such as a phosphorothioate or phosphoramidite. This unit discusses four alternative methods for synthesizing nucleoside H‐phosphonate monoesters. The methods are efficient and experimentally simple, and use readily available reagents. The unit describes the activation of the monoesters, as well as competing acylation and other potential side reactions.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143594/1/cpnc0304.pd

Synthetic Strategies and Parameters Involved in the Synthesis of Oligodeoxyribo‐ and Oligoribonucleotides According to the H

Oligonucleotides can be synthesized by condensing a protected nucleoside H‐phosphonate monoester with a second nucleoside in the presence of a coupling agent to produce a dinucleoside H‐phosphonate diester. This can then be converted to a dinucleoside phosphate or to a backbone‐modified analog such as a phosphorothioate or phosphoramidite. This unit discusses four alternative methods for synthesizing nucleoside H‐phosphonate monoesters. The methods are efficient and experimentally simple, and use readily available reagents. The unit describes the activation of the monoesters, as well as competing acylation and other potential side reactions.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143625/1/cpnc0304.pd