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9 results on '"Singh, Rajdeo"'

6. Metallurgical investigations of Indo-Sasanian Copper-Silver alloy coins of Gurjara-Pratiharas dynasty

Author

Meenakshi Malsure, Singh Rajdeo, and Preeti Verma

Subjects
Copper oxide, Mining engineering. Metallurgy, Materials science, Mechanical Engineering, Alloy, Metallurgy, TN1-997, Metals and Alloys, chemistry.chemical_element, engineering.material, Microstructure, Casting, Copper, Corrosion, stomatognathic diseases, chemistry.chemical_compound, indo-sasanian, copper-silver coins, dendrite, paratacamite, casting, corrosion, chemistry, Impurity, otorhinolaryngologic diseases, engineering, Chemical composition
Abstract

Five Indo-Sasanian copper-silver alloy coins were examined to determine the chemical composition and fabrication route. Based on iconography, the investigated coins were dated in the range 8th to 9th century CE. The chemical composition of the coins confirmed that the coins were made of copper-silver alloy. The percentage of silver was found to be in the range from 14 wt.% to 16 wt.%, and other elements iron and lead were present as impurities. There was no significant difference in the chemical composition from the surface to the center. Chlorine was detected in the localized green corrosion, which confirms the presence of active corrosion, and coins must be conserved by giving proper conservation treatment. The formation of unusual active corrosion compounds i.e. paratacamite was identified by the XRD, and this may be formed due to the exposure of coins to river water and soil. Optical microscopy revealed the dendritic and dual-phase structure, and the presence of dendrite showed that the coins were manufactured by the casting. It was confirmed from the optical microscopy that coins were not subjected to heat treatment and deformation. The microstructure consists of dual phases, in which the white phase is silver-rich, and the black phase is rich in copper. The morphology and chemical composition of the corrosion compound formed on the surface of the coins mainly indicated the formation of copper oxide with different morphology.

Published
2020

9. Land use practices in the Central Himalayan region affect soil enzyme activities and their relationship with carbon pools.

Author

Kalambukattu, JustinGeorge, Singh, RajDeo, Patra, AshokK., Arunkumar, K., and Pote, John

Subjects
*LAND use, *SOIL enzymology, *DEHYDROGENASES, *PHOSPHATASES, *CARBON in soils, *FOREST soils
Abstract

Activities of soil enzymes dehydrogenase, acid phosphatase, alkaline phosphatase, and arylsulfatase were evaluated under the different land use and cropping systems in the Almora region of Central Himalaya, India. The dehydrogenase activity recorded the highest value in undisturbed forest (4.68 µg TPF g−1h−1) and lowest in barren land (0.74 µg TPF g−1h−1). The acid phosphatase activities varied between different systems; being lowest in barren land followed by fodder, soybean-wheat, organic system, and the highest in undisturbed forest soil. The average alkaline phosphatase activity ranged from 13.3 µg PNP g−1h−1in barren land to 139.9 µg PNP g−1h−1in undisturbed forest. The average arylsulfatase activity ranged from 7.30 µg PNP g−1h−1in barren land to 184.9 µg PNP g−1h−1in undisturbed forest. Most of the enzyme activities showed higher values in summer and at 0–5 cm depth. Significant positive correlations were obtained between enzyme activities and various carbon fractions such as microbial biomass C, particulate organic C and labile C, of which labile carbon was found to be the most strongly associated fraction with the enzyme activities. Our study thus revealed that the cultivation of Himalayan soils has significantly reduced the enzyme activities and that needs adequate attention for long-term sustainable use of soil resources in the region. [ABSTRACT FROM PUBLISHER]

Published
2013
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