Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Catalysis & Excited state. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Heme-Cu bound aβ peptides: spectroscopic characterization, reactivity, and relevance to Alzheimer's disease.

Abstract: Recently, it has been shown that heme binds to Aβ peptides which may play a major role in Alzheimer's disease (AD). This study illustrates that Aβ peptides can bind both Cu and heme cofactors at the same time. Both cofactors have unique spectroscopic and electrochemical features which are unaffected in the presence of the other, implying that they are electronically, chemically, and electrochemically uncoupled. These data clearly indicate that Cu cannot bind to three histidine residues simultaneously in Cu-Aβ complexes as previously proposed, since one of the histidines is involved in binding heme. The heme-Aβ and the heme-Cu-Aβ peptide complexes function as peroxidases. Interestingly, the Cu-Aβ complex also exhibits peroxidase activity, which may have significant implications in AD. Both Cu(+)-Aβ and heme (Fe(2+))-Aβ complexes reduce O(2) to H(2)O(2) quantitatively. Only one of the two electrons that are required for the reduction of O(2) to H(2)O(2) is derived from the reduced metal site, while the Tyr(10) residue of the native Aβ peptide donates the second electron. This Tyr(10) residue, the source of electron for the generation of partially reduced oxygen species (PROS, e.g., H(2)O(2)) is absent in rodents, which do not get affected by AD. When both heme and Cu are bound to the Aβ peptides, which is likely to happen physiologically, the amount of toxic PROS generated is maximum, implying that heme-Cu-Aβ complexes could potentially be most toxic for AD.

Facile Synthesis of Silver Nanoparticles Decorated Magnetic-Chitosan Microsphere for Efficient Removal of Dyes and Microbial Contaminants

Abstract: A facile and rapid synthesis of core–shell type magnetite-chitosan microsphere decorated with silver nanoparticles (MCSM) is described. The composition and structure of the as-synthesized microsphere characterized by various spectroscopic and microscopic techniques demonstrated formation of 3.63 ± 0.76 μm MCSM with decoration of silver nanoparticles (AgNPs) having 16 ± 2.5 nm size. The thermogravimetric analysis (TGA) data showed good thermal stability, whereas vibrating sample magnetometry (VSM) analysis indicated the superparamagnetic behavior of the as-synthesized microsphere. The adsorptive removal and antimicrobial property of MCSM was explored for eco-friendly and cost-effective water purification. The MCSM removed 99.99% microbial contaminants and 99.5% of dyes from single as well as multicomponent systems from water bodies efficiently. Furthermore, the dye removal capacity of MCSM (qe = 271.2 ± 14.5 mg/g) was found to be higher compared to the other nanoadsorbents attributing to the high effective...

Large conductance switching and binary operation in organic devices: Role of functional groups

Abstract: We have realized tuning of electronic memory-switching property via functional group modification in solid-state devices. Apart from their large ON/OFF ratio and long memory retention time, solid-state devices sustain repetitive switching between the two ON/OFF states at high frequencies. We have chosen several molecular systems with same backbone structure and tuned ON/OFF ratio from 4 to 300 000 simply by increasing the number of deactivating groups. A key to the large ON/OFF ratio in these devices has been the presence of acceptor groups in the molecules and consequently low OFF state current. We analyzed the appearance of ON state in terms of conjugation restoration of the molecules. A redox active group has been found to be necessary in the molecules for continuous flip-flop between “1” and “0” states for random access memory (RAM) applications.