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Effect of Ag on Sn-Cu and Sn-Zn lead free solders

100%

Alam S. N. , Mishra P. , Kumar R.

tom Vol. 33, No. 2

317--330

Lead and lead-containing compounds are considered as toxic substances due to their detrimental effect on the environment. Sn-based soldering systems, like Sn-Cu and Sn-Zn are considered as the most promising candidates to replace the eutectic Sn-Pb solder compared to other solders because of their low melting temperature and favorable properties. Eutectic Sn-0.7 wt.% Cu and near eutectic composition Sn-8 wt.% Zn solders have been considered here for study. For the Sn-Cu system, besides the eutectic Sn-0.7 wt.% Cu composition, Sn-1Cu and Sn-2Cu were studied. Three compositions containing Ag: Sn-2Ag-0.7Cu, Sn-2.5Ag-0.7Cu and Sn-4.5Ag-0.7Cu were also developed. Ag was added to the eutectic Sn-0.7 wt.% Cu composition in order to reduce the melting temperature of the eutectic alloy and to enhance the mechanical properties. For the Sn-Zn system, besides the Sn-8 wt.% Zn near eutectic composition, Sn-8Zn-0.05Ag, Sn-8Zn-0.1Ag and Sn-8Zn-0.2Ag solder alloys were developed. The structure and morphology of the solder alloys were analyzed using a scanning electron microscope (SEM), filed emission scanning electron microscope (FESEM), electron diffraction X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Thermal analysis of the alloys was also done using a differential scanning calorimeter (DSC). Trace additions of Ag have been found to significantly reduce the melting temperature of the Sn-0.7 wt.% Cu and Sn-8 wt.% Zn alloys.

Localization of nitrogenase and nitrate reductase in the Cycas-Anabaena cycadeae association

100%

Sharma A. , Mishra P. , Kumar A.

Acta Biologica Cracoviensia. Series Botanica

2004

tom 46

213-216

Induction of nitrate reductase (NR) activity in coralloid roots of Cycas revoluta was observed after 8 h incubation in 0.02 M KNO3. Other plants growing near Cycas showed a higher level of NR immediately when incubated in KNO3. In contrast to NR, intact coralloid roots showed very high nitrogenase activity (~1.2 to 1.6 µmol C2H4 g fresh wt-1 h-1) under both light and dark conditions as compared to transverse sections of roots. Localization of NR and nitrogenase was tested in coralloid roots using different sets of roots and also in the endophyte. Our results showed that NR activity was mainly due to the endophyte (Anabaena cycadeae); coralloid roots lacked it, as no NR activity was observed in chloramphenicol-treated intact root samples.

Postharvest physicochemical changes in mutant (dg, ogc, and rin) and non-mutant tomatoes

88%

Siddiqui M. A. , Chakraborty I. , Mishra P. , Hazra P. , Ayala-Zavala J. F.

nr 01

Early postharvest decay of tomato is a major concern of research. Several pre and postharvest efforts have been suggested to improve the shelf life of commercially grown tomatoes. However, finding the cultivars with increased shelf life is not yet achieved. Our study focused on the characterization of two color mutants [dg (BCT-115) and ogc (BCT-119)], one ripening mutant [rin (BCT-111)], and seven normal tomato genotypes [Berika (high lycopene) Punjab, Chhuhara, FEB-2, BCT-53, Patharkutchi, CLN-B, and CLN-R] using different physicochemical and subjective variables to acknowledge the storage potential at 25 ± 1 C and RH 80–82 %. There were significant variations in storage life among all tomato genotypes. Except ogc, the mutant (dg and rin) tomatoes showed longer shelf life in relation to normal tomatoes. Based on their storability, the genotypes were classified into three groups i.e. shelf life less than 15 days [CLN-B, BCT-53, CLN-R, and BCT-119 (ogc)], 15–18 days [FEB-2, Punjab Chhuhara, Patharkutchi, and Berika] and more than 18 days [BCT-115 (dg) and BCT-111 (rin)]. We suggest that selecting the genotype/cultivar having longer shelf life during formulation of breeding strategy could improve the marketability of tomato fruits for relatively longer period.

A high performance visible-NIR detector using aligned TiS3 nanoribbons

63%

Talib M. , Manzoor S. , Gulia P. , Aziz F. , Malik N. , Jain P. , Faisal , Khatun S. , Mishra P.

tom 121