Graphene coating on copper (Cu) is shown to increase the resistance of the metal to electrochemical degradation by one and half orders of magnitude. Detailed electrochemical characterization in ...aggressive chloride environment shows the impedance of Cu increasing dramatically and the anodic and cathodic current densities of the coated Cu becoming nearly 1–2 orders of magnitude smaller when coated with graphene. The observations are counterintuitive as graphite in contact with metals increases metallic corrosion. The results can bring paradigm changes in the development of anti-corrosion coatings using conformal, ultrathin graphene films.
Lack of uniformity and generation of defects including grain boundaries and wrinkles in graphene coatings synthesized using chemical vapour deposition (CVD) adversely affect the durability of these ...coatings. In order to control the defect density and to improve the durability of corrosion resistance of the resultant graphene coating, a fundamental understanding of the influence of the CVD parameters on the defect density is of utmost importance. In this study, the influences of hydrogen flow during graphene growth and the cooling rate on the defect density and barrier properties of a graphene coating have been investigated. A thorough microscopic and spectroscopic investigation revealed that (i) slow cooling hindered the formation of graphene coating irrespective of the presence or absence of hydrogen flow, and (ii) under rapid cooling condition, absence of hydrogen flow restricted wrinkle formation on the resultant coating. Diminished wrinkle formation in absence of hydrogen flow significantly improved the durability of the resultant coating. Based on an in-depth electrochemical impedance spectroscopic investigation, a mechanism has been proposed, which was further corroborated with the post-corrosion analyses using X-ray photoelectron spectroscopy and scanning electron microscopy. This study provides a new direction to achieve graphene coatings with minimal defect density and excellent barrier properties.
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To evaluate Ochrobactrum anthropi TRS-2 isolated from tea rhizosphere and its talc based formulation for growth promotion and management of brown root rot disease of tea. Ochrobactrum anthropi TRS-2, ...isolated from tea rhizosphere could solubilize phosphate, produce siderophore and IAA in vitro and also exhibited antifungal activity against six test pathogens. Application of an aqueous suspension of O. anthropi to the rhizosphere of nursery grown tea seedlings of five varieties of tea (TV-18, T-17, HV-39, S-449, UP-3 and) led to enhanced growth of the treated plants, as evidenced by increase in height, in the number of shoots and number of leaves per shoot. Treatment with O. anthropi also decreased brown root rot of tea, caused by Phellinus noxius. Multifold increase in activities of chitinase, β-1,3-glucanase, peroxidase and phenylalanine ammonia lyase in tea plants was observed on application of O. anthropi to soil followed by inoculation with P. noxius. A concomitant increase in accumulation of phenolics was also obtained. Further, talc based formulation of O. anthropi was prepared and its survival determined every month up to a period of 12 months. Ochrobactrum anthropi could survive in the formulation up to a period of 9 months with a concentration of 7·0 log₁₀ CFU g⁻¹, after which there was a decline. Talc formulation was as effective as aqueous suspensions in both plant growth promotion and disease suppression. Ochrobactrum anthropi, either in aqueous suspension or as talc formulation induced growth of tea plants and suppressed brown root rot disease. It induced defense responses in tea plants. Ochrobactrum anthropi and its talc based formulation can be considered as an addition to available plant growth promoting rhizobacteria (PGPR) currently being used for field application. The present study offers a scope of utilizing this bacterium for growth promotion and disease management which would help in reduction of the use of chemicals in tea plantations.
In the receiver operating characteristic paradigm the observer assigns a single rating to each image and the location of the perceived abnormality, if any, is ignored. In the free-response receiver ...operating characteristic paradigm the observer is free to mark and rate as many suspicious regions as are considered clinically reportable. Credit for a correct localization is given only if a mark is sufficiently close to an actual lesion; otherwise, the observer's mark is scored as a location-level false positive. Until fairly recently there existed no accepted method for analyzing the resulting relatively unstructured data containing random numbers of mark-rating pairs per image. This report reviews the history of work in this field, which has now spanned more than five decades. It introduces terminology used to describe the paradigm, proposed measures of performance (figures of merit), ways of visualizing the data (operating characteristics), and software for analyzing free-response receiver operating characteristic studies.
Soil microorganisms with potential for alleviation of abiotic stresses in combination with plant growth promotion would be extremely useful tools in sustainable agriculture. To this end, the present ...study was initiated where forty-five salt tolerant bacterial isolates with ability to grow in high salt medium were obtained from the rhizosphere of
Triticum aestivum
and
Imperata cylindrica
. These bacteria were tested for plant-growth-promoting rhizobacteria traits in vitro such as phosphate solubilization, siderophore, ACC deaminase and IAA production. Of the forty-five isolates, W10 from wheat rhizosphere and IP8 from blady grass rhizosphere, which tested positive in all the tests were identified by morpholological, biochemical and 16SrDNA sequencing as
Bacillus safensis
and
Ochrobactrum pseudogregnonense
respectively and selected for in vivo studies. Both the bacteria could promote growth in six varieties of wheat tested in terms of increase in root and shoot biomass, height of plants, yield, as well as increase in chlorophyll content. Besides, the wheat plants could withstand water stress more efficiently in presence of the bacteria as indicated by delay in appearance of wilting symptoms increases in relative water content of treated water stressed plants in comparison to untreated stressed ones, and elevated antioxidant responses. Enhanced antioxidant responses were evident as elevated activities of enzymes such as catalase, peroxidase, ascorbate peroxidase, superoxide dismutase and glutathione reductase as well as increased accumulation of antioxidants such as carotenoids and ascorbate. Results clearly indicate that the ability of wheat plants to withstand water stress is enhanced by application of these bacteria which also function as plant growth promoting rhizobacteria.
Considering the high energy neutron environment in a nuclear fusion reactor, Reduced Activation type Ferritic/Martensitic Steels (RAFMS) containing tungsten, have been carefully curated from their ...surrogate Cr–Mo type Ferritic/Martensitic Steels (FMS). The substitution of molybdenum by tungsten improved the radiation stability and mechanical characteristics RAFMS. However, the effect of tungsten on the liquid metal corrosion resistance of FMS has not been well investigated. The current work attempts to estimate liquid metal compatibility by examining the surface oxides of Indian RAFMS (IN RAFMS) and its surrogate steel, P91 (9Cr-1Mo), using X-ray Photoelectron Spectroscopy. Subsequently, thermodynamic calculations have been used to establish the stability of such oxides in both ambient circumstances and liquid lead–lithium eutectic alloy (Pb–Li). The results showed that tungsten can provide a higher resistance to liquid metal attack than molybdenum because its oxides are more stable. Actual corrosion experiments with IN RAFMS and P91 were performed in liquid Pb–Li for a durations upto 2000 h, successfully validating the above stated prediction.
Major elements and trace metals were analyzed in four sediment cores recovered along a transect in the Mandovi estuary for their distribution, provenance and early diagenesis. The sediments were ...clayey silts in cores from the upper/lower estuary and sand-dominated in cores from the middle estuary/bay. Organic carbon (OC) content varied from 0.5 to 4%, with higher values in fine-grained sediments. The mean Fe and Mn contents of sediments from the upper/middle estuary were 3–5 times and 8–13 times, respectively higher than the reference sediment (RS) from the same estuary. The mean Fe and Mn contents of sediments from the lower estuary/bay were close to the RS. Strong inter-metal correlation among Ti, V, Cr and Zr in all the cores indicated their contribution from a common source, probably the laterites from hinterland. Trace metals were more enriched in fine-grained sediments than in sand-dominated sediments. Early diagenetic control on the redistribution of metal is evident in core sediments from the middle estuary to Bay. The distribution of Mo, U and Pb followed that of Fe and Mn in the upper estuary and OC in the lower estuary/bay. Our results indicated strong anthropogenic contribution of metals from ore deposits in the upper/middle estuary. The Mn and Cr contents of sediment in the upper/middle estuary and Fe in the middle estuary were highly enriched suggestive of ‘significant pollution signal’. More trace metals from the middle estuary were moderately enriched. Speciation studies showed Mn and Pb occurred abundantly in non-residual phases. High Mn content and its high percentage in exchangeable and reductive phases indicate that it was susceptible to be mobilized. However, Fe, Cu and Ni occurred abundantly in residual phases and less percentage of them were expected to be bio-available.
•Major and trace metal distribution in 4 sediment cores from the Mandovi estuary.•Contrasting metal contents in the upper/middle estuary and lower estuary/bay.•Two distinct sources of sediments, ore deposits and laterites.•Trace metal distribution controlled by grain size, OC and early diagenesis.•High Mn and Pb in non-residual phase and, high Fe, Ni and Cu in residual phases.
The aim of this work was to validate and compare the statistical powers of proposed methods for analyzing free-response data using a search-model-based simulator.
A free-response data simulator is ...described that can model a single reader interpreting the same cases in two modalities, or two computer-aided detection (CAD) algorithms, or two human observers, interpreting the same cases in one modality. A variance components model, analogous to the Roe and Metz receiver-operating characteristic (ROC) data simulator, is described; it models intracase and intermodality correlations in free-response studies. Two generic observers were simulated: a quasi-human observer and a quasi-CAD algorithm. Null hypothesis (NH) validity and statistical powers of ROC, jackknife alternative free-response operating characteristic (JAFROC), a variant of JAFROC termed JAFROC-1, initial detection and candidate analysis (IDCA), and a nonparametric (NP) approach were investigated.
All methods had valid NH behavior over a wide range of simulator parameters. For equal numbers of normal and abnormal cases, for the human observer, the statistical power ranking of the methods was JAFROC-1 > JAFROC > (IDCA approximately NP) > ROC. For the CAD algorithm, the ranking was (NP approximately IDCA) > (JAFROC-1 approximately JAFROC) > ROC. In either case, the statistical power of the highest ranked method exceeded that of the lowest ranked method by about a factor of two. Dependence of statistical power on simulator parameters followed expected trends. For data sets with more abnormal cases than normal cases, JAFROC-1 power significantly exceeded JAFROC power.
Based on this work, the recommendation is to use JAFROC-1 for human observers (including human observers with CAD assist) and the NP method for evaluating CAD algorithms.
The modelling of the thermo-kinetic properties of uranium-plutonium mixed oxide (MOX) is of utmost importance for optimizing its synthesis and for predicting its behaviour in Fast Breeder Reactors. ...Despite the stakes and likely because of experimental issues, little or no experimental data are available for the entire MOX system. We circumvent here the difficulties by developing a mobility database for plutonium using the DICTRA code. A well-established model of MOX formalized within the Compound Energy Formalism ensures the thermodynamic description. Rationalisation of the mobility parameters combined with the use of both cBΩ model and the few experimental data lead to a full and comprehensive description of plutonium self-diffusion in MOX for any plutonium content, O/M ratio and temperature. Additionally, we show that the observed plateau of the self-diffusion as a function of the oxygen to metal ratio (O/M) is related to the constant Pu3+ fraction for very low O/M ratio. Moreover, the observed minimum close to O/M = 2 is found for the lowest mobility of Pu4+.
•The first mobility database for plutonium diffusion in (U,Pu)O2±x is developed using DICTRA.•The diffusion properties are linked to the defect chemistry by the Compound Energy Formalism.•The cBΩ method is applied to calculate plutonium diffusion coefficient in plutonia.•Plutonium diffusion in (U,Pu)O2±x is modelled as a function of temperature, plutonium content and oxygen to metal ratio.
Abstract
We discuss the importance of Fe
23+
in determining the line intensities of the Fe
xxv
K
α
complex in an optically thick cloud, and investigate resonant auger destruction (RAD) with CLOUDY. ...Although initially motivated by the Perseus cluster, our calculations are extended to the wide range of column densities encountered in astronomy. A Fe
xxv
line photon can change/lose its identity upon absorption by three-electron iron as a result of “line interlocking.” This may lead to the autoionization of the absorbing ion, ultimately destroying the Fe
xxv
K
α
photon by RAD. Out of the four members in the Fe
xxv
K
α
complex, a significant fraction of the x line photons are absorbed by Fe
23+
and destroyed, causing the x line intensity to decrease. For example, at a hydrogen column density of 10
25
cm
−2
, ∼32% of x photons are destroyed due to RAD while w is mostly unaffected. The line intensity of y is slightly (≤2%) reduced. z is not directly affected by RAD, but the contrasting behavior between z and x line intensities points toward the possible conversion of a tiny fraction (∼2%) of x photons into z photons. The change in line intensities due to electron scattering escape off fast thermal electrons is also discussed.
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