Chemical signature of the superconducting phase in the nd-ce-cu-o system     

Nath A  Kopelev NS  Chechersky V  Peng JL  Greene RL  O BH  Larkin MI  Markert JT 《Science (New York, N.Y.)》1994,265(5168):73-74

The electron-doped material Nd2-xCexCuO(4) becomes superconducting with a Ce(4+) composition around 0.16, but only after removal of a minuscule amount of extraneous oxygen. This enigmatic behavior was addressed here. A small fraction of copper in the CuO(2) planes of Nd2-xCexCuO(4) was substituted by cobalt-57, which serves as a microprobe of the chemical environment. Deoxygenation brought about little change in the M?ssbauer spectra both above and below the optimal superconducting concentration; however, for x = 0.16 a change was observed. In the latter, a major fraction of the magnetically split, five-coordinate species showed itself as a paramagnetically relaxed doublet upon deoxygenation. The abundance of the paramagnetically relaxed species corresponds closely to the diamagnetic volume fraction and thus provides a microscopic signature of the superconducting phase.  相似文献   

Enzyme activities and microbial biomass in coastal soils of India   总被引：1，自引：0，他引：1  

Sudipta Tripathi  Ashis Chakraborty  Bimal Kumar Bandyopadhyay 《Soil biology & biochemistry》2007,39(11):2840-2848

Soil salinity is a serious problem for agriculture in coastal regions, wherein salinity is temporal in nature. We studied the effect of salinity, in summer, monsoon and winter seasons, on microbial biomass carbon (MBC) and enzyme activities (EAs) of the salt-affected soils of the coastal region of the Bay of Bengal, Sundarbans, India. The average pH of soils collected from different sites, during different seasons varied from 4.8 to 7.8. The average organic C (OC) and total N (TN) content of the soils ranged between 5.2-14.1 and 0.6-1.4 g kg⁻¹, respectively. The electrical conductivity of the saturation extract (ECe) of soils, averaged over season, varied from 2.2 to 16.3 dSm⁻¹. The ECe of the soils increased five fold during the summer season (13.8 dSm⁻¹) than the monsoon season (2.7 dSm⁻¹). The major cation and anion detected were Na⁺ and Cl⁻, respectively. Seasonality exerted considerable effects on MBC and soil EAs, with the lowest values recorded during the summer season. The activities of β-glucosidase, urease, acid phosphatase and alkaline phosphatase were similar during the winter and monsoon season. The dehydrogenase activity of soils was higher in monsoon than in winter. Average MBC, dehydrogenase, β-glucosidase, urease, acid phosphatase and alkaline phosphatase activities of the saline soils ranged from 125 to 346 mg kg⁻¹ oven dry soil, 6-9.9 mg triphenyl formazan (TPF) kg⁻¹ oven dry soil h⁻¹, 18-53 mg p-nitro phenol (PNP) kg⁻¹ oven dry soil h⁻¹, 38-86 mg urea hydrolyzed kg⁻¹ oven dry soil h⁻¹, 213-584 mg PNP kg⁻¹ oven dry soil h⁻¹ and 176-362 mg PNP g⁻¹ oven dry soil h⁻¹, respectively. The same for the non-saline soils were 274-446 mg kg⁻¹ oven dry soil, 8.8-14.4 mg TPF kg⁻¹ oven dry soil h⁻¹, 41-80 mg PNP kg⁻¹ oven dry soil h⁻¹, 89-134 mg urea hydrolyzed kg⁻¹ oven dry soil h⁻¹, 219-287 mg PNP kg⁻¹ oven dry soil h⁻¹ and 407-417 mg PNP kg⁻¹ oven dry soil h⁻¹, respectively. About 48%, 82%, 48%, 63%, 40% and 48% variation in MBC, dehydrogenase activity, β-glucosidase activity, urease activity, acid phosphatase activity and alkaline phosphatase activity, respectively, could be explained by the variation in ECe of saline soils. Suppression of EAs of the coastal soils during summer due to salinity rise is of immense agronomic significance and needs suitable interventions for sustainable crop production.  相似文献   

Fungal air-spora inside the central library of Gorakhpur University     

R. N. Tripathi 《Water, air, and soil pollution》1987,34(2):125-134

The study of the air-spora in the Central Library of Gorakhpur University indicated the presence of 19 different types of fungal spores. Amongst these Aspergillus niger, A. favus, Cladosporium spp., Curvularia spp., Paecilomyces sp., Penicillium spp., and periconia sp. were more than 80.5% followed by species of Absidia, Alternaria, Chaetomium, Mucor, Rhizopus, Trichophyton, and Cercospora. Fungal spores showed time trends during the study period. The fungal spore concentrations gradually increased from July to September and attained their maximum in September to October and thereafter decreased. Besides fungal spores, small pieces of paper, dust particles and insect derivatives loaded with fungal mycelium and bacterium were also observed throughout the investigation period.  相似文献   

Nutrient immobilization and release patterns during plant decomposition in a dry tropical bamboo savanna,India   总被引：3，自引：0，他引：3  

S. K. Tripathi  K. P. Singh 《Biology and Fertility of Soils》1992,14(3):191-199

Summary Decomposition and changes in nutrient content of six litter types (leaves, sheaths, roots, twigs, and wood of bamboo, and grass shoots) were studied in nylon net bags for 2 years. The annual weight loss was (% of initial) bamboo leaves 56.5, bamboo sheaths 79.5, bamboo roots 65.8, bamboo twigs 49.6, bamboo wood 31.2, and grass shoots 74.9. Elemental mobility followed the order K>Na>C>P>Ca>N in all components except wood. Generally, an initial increase was followed by a consistent decrease in the contents of N (leaves), P (leaves, roots, wood) and Ca (leaves, roots, grass), and Na (wood). Most of the nutrients were immobilized in the rainy season. C and K contents showed a constant decrease throughout the decomposition period. Materials with a greater C:N ratio (>50) tended to accumulate more nutrients and retain them for longer, except for the bamboo twigs. The critical C:N ratio (at which a net release of N occured) for the leaf material was 25. Litter components with more initial N (sheaths) showed greater weight loss than those with less N (leaves, twigs, and wood). Overall, N and P were lost at the slowest rates while C and K were lost at faster rates. Initial lignin, lignin: N, C:N and C concentrations had a better predictive value for annual weight loss and nutrient release in bivariate relationships. A combination of the initial lignin value and the C: N ratio explained 93% of the variation in annual weight loss. A significant relationship was also observed between the annual weight loss rate and the nutrient mineralization/release rate.  相似文献   

Non-arrowing and broad-leaved mutants in Rhodes grass (Chloris gayana Kunth.)     

G. Krishna  G. Shivashankar  J. Nath 《Euphytica》1984,33(2):525-528

Summary Non-arrowing and broad-leaved mutants of Rhodes grass have been isolated following gamma irradiation. The green forage yield in non-arrowing and broad-leaved types were respectively 67 and 171 percent more than the control. Crude protein, nitrogen and calcium fractions nearly doubled in the non-arrowing type and remained approxymately the same in the broad-leaved type over controls.  相似文献   

Inheritance and linkage relationship of scent in rice   总被引：6，自引：0，他引：6  

R. S. Tripathi  M. J. B. K. Rao 《Euphytica》1979,28(2):319-323

Summary The inheritance of scent in rice and linkage relationship of genes governing scent with those controlling leaf sheath colour, ripening hull colour and apiculus pigmentation were studied in a cross between Pankaj (nonscented) and Kalabhat (scented) rice cultivars. The scent was identified by leaf analysis.Two dominant complementary genes Sk ₁ and Sk ₂ were found to be responsible for controlling scent. Either of the genes produce mild scent, the presence of both Sk ₁ and Sk ₂ is necessary for production of parental type scent. The genes were independent of other genes controlling leaf sheath colour, ripening hull colour and apiculus pigmentation.  相似文献   

Allelic relationships of flowering time genes in chickpea     

Pooran M. Gaur  Srinivasan Samineni  Shailesh Tripathi  Rajeev K. Varshney  C. L. Laxmipathi Gowda 《Euphytica》2015,203(2):295-308

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A scientometric mapping of research on Aeromonas infection in fish across the world (1998–2020)     

Rathinam  R. Bharathi  Iburahim  S. Abuthagir  Ramanan  S. Suresh  Tripathi  Gayatri 《Aquaculture International》2022,30(1):341-363

Aeromonas spp are the most common devastating fish bacterial pathogens associated with a wide range of cultured freshwater fish resulting in mass mortality. The present study plots the Aeromonas research output in fish during 1998–2020 by means of the Web of Science (WoS) database. A total of 1944 publications were used for this investigation to evaluate the scientific productivity in this selected subject area. Global publication share, rank, and its development in terms of research and bibliometric indices such as overall citations, h-index, and average citation per paper were also analysed. China ranked first in terms of total publications among the most productive countries and accounted for 26.18% of the total publications. The network visualisation map revealed that the lead collaborating country was China; however, the collaboration between countries was found to be very less. Lokta’s law was noticed not to be valid for Aeromonas research. The study showed that the funding granted to the research investigations and their research productivity in terms of total publications were correlated positively. The results of the current study displayed the trend of “Aeromonas infection in fish” related research investigations published during 1998–2020. This study also highlighted the focused research areas on this topic on which the future areas of research can be determined by fellow researchers in this specific field. This study also suggests enhancing the research efforts on this bacterial pathogen which has the potential to implicate huge economic loss to the fish farming population in the world.

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Development of a specific molecular tool for detecting Xanthomonas campestris pv. musacearum     

S. Adikini  L. Tripathi  F. Beed  G. Tusiime  E. M. Magembe  D. J. Kim 《Plant pathology》2011,60(3):443-452

A specific and rapid diagnostic tool has been developed to detect Xanthomonas campestris pv. musacearum, the causal agent of bacterial wilt of banana. PCR primers were developed from intergenic regions of X. campestris pv. musacearum following its partial sequence. A total of 48 primers were tested for specificity to X. campestris pv. musacearum strains collected from various regions in Uganda. These were also tested for specificity against related Xanthomonas species from the vasicola group, Xanthomonas species pathogenic to other crops, and against those existing saprophytically on banana plants. Seven primer sets (Xcm12, Xcm35, Xcm36, Xcm38, Xcm44, Xcm47 and Xcm48) were found to be very specific to X. campestris pv. musacearum. These primer sets directed the amplification of the expected product for all 52 strains of X. campestris pv. musacearum collected from different locations in Uganda. No amplification products were obtained with unrelated phytopathogenic bacteria or endophytic/epiphytic bacteria from banana. A detection limit of 10³ CFU mL^?1 corresponding to about four cells per PCR reaction was observed when X. campestris pv. musacearum cells were used for all the seven primer sets. The DNA samples from symptomless plant tissues also tested positive with primer set Xcm38. The specific PCR method described here is a valuable diagnostic tool which can be used to detect the pathogen at early stages of infection and monitor disease.  相似文献   

Micronutrients (Fe,Mn, Zn and Cu) balance under long-term application of fertilizer and manure in a tropical rice-rice system     

Mohammad Shahid  Arvind Kumar Shukla  Pratap Bhattacharyya  Rahul Tripathi  Sangita Mohanty  Anjani Kumar  Banwari Lal  Priyanka Gautam  Rajagounder Raja  Bipin Bihari Panda  Brundaban Das  Amaresh Kumar Nayak 《Journal of Soils and Sediments》2016,16(3):737-747

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