The synthesis of various nanoscale materials, such as nanoparticles, nanowires of Au, Pt, Ni Co, Fe, Ag etc., by electrodeposition techniques have been demonstrated in this article. Both ...potentiostatic and galvanostatic methods were employed to carry out the electrodeposition process under different potential ranges, time durations, and current densities. The electrochemical behavior of the deposited nanoparticles on various substrates was investigated by cyclic voltammetric and chronoamperometric techniques. The synthesis of mono-dispersed gold (Au) nanoparticles on indium tin oxide (ITO) coated glass, preparation of Au nanorods on nanoporous anodic alumina oxide (AAO), formation of Au nanoclusters on polypyrrole-modified glassy carbon electrode and one-step electrodeposition of nickel nanoparticle chains embedded in TiO
2
etc. have been highlighted in this article. The potential applications of synthesized nanoparticles such as the role of maghemite (Fe
2
O
3
) in arsenic remediation, higher electrocatalytic activity of Ag nanoclusters for the reduction of benzyl chloride, and the role of C
60
nanoparticle-doped carbon film in fabrication processes are also presented in this article.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Background
Environmental-assisted fatigue (EAF) is a major issue for the long-term survival of nuclear power plant fleets in the U.S. and worldwide. Multi-material welded regions (e.g., nozzles) and ...other high-stress regions of reactor coolant system (RCS) components are prone to EAF-related damage.
Objective
The discussed work describes a system-level finite element (FE) model of RCS components of a pressurized water reactor (PWR). This is with the goal of predicting the stress hotspots, strain residuals, strain amplitudes and the resulting fatigue lives.
Methods
The FE model was developed considering system-level loading conditions (under connected system thermal–mechanical boundary conditions). Thermal–mechanical stress analysis was performed considering thermal stratification and a design-basis reactor loading cycle. Based on the FE model results, the strain residuals, strain amplitudes and resulting fatigue lives of RCS components were predicted.
Results
The results show that some of the RCS components can have significantly different strain amplitudes, residual strain, and fatigue lives, despite having similar geometry and material. Higher residual strain can lead to accelerated cyclic hardening of material and the associated effect of EAF. The simulated component-level strain profile (under realistic multi-axial-multi-physics loading cycle) can guide the selection of appropriate test inputs for conducting laboratory-scale EAF tests, which is a focus of future works.
Conclusions
Despite similar geometry and material the RCS component can have significantly different strain profiles and resulting fatigue lives. The discussed approach can help to identify and prioritize the RCS components for conducting expensive nondestructive evaluation (NDE) inspections.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
ABSTRACT We model the atmospheres and spectra of Earth-like planets orbiting the entire grid of M dwarfs for active and inactive stellar models with Teff = 2300 K to Teff = 3800 K and for six ...observed MUSCLES M dwarfs with UV radiation data. We set the Earth-like planets at the 1 AU equivalent distance and show spectra from the visible to IR (0.4-20 m) to compare detectability of features in different wavelength ranges with the James Webb Space Telescope and other future ground- and spaced-based missions to characterize exo-Earths. We focus on the effect of UV activity levels on detectable atmospheric features that indicate habitability on Earth, namely, H2O, O3, CH4, N2O, and CH3Cl. To observe signatures of life-O2/O3 in combination with reducing species like CH4-we find that early and active M dwarfs are the best targets of the M star grid for future telescopes. The O2 spectral feature at 0.76 m is increasingly difficult to detect in reflected light of later M dwarfs owing to low stellar flux in that wavelength region. N2O, another biosignature detectable in the IR, builds up to observable concentrations in our planetary models around M dwarfs with low UV flux. CH3Cl could become detectable, depending on the depth of the overlapping N2O feature. We present a spectral database of Earth-like planets around cool stars for directly imaged planets as a framework for interpreting future light curves, direct imaging, and secondary eclipse measurements of the atmospheres of terrestrial planets in the habitable zone to design and assess future telescope capabilities.
An Archaean continent 'SIWA', an acronym for South India-Western Australia, comprising the Bastar-Dharwar craton, the Yilgarn craton, the Napier Complex, and the Vestfold Hills has been identified ...from palaeomagnetic and spatio-temporal data. This assembly was dispersed in three phases with the development of the proto-Indian ocean. The first and second events ~2350 and ~2000 Ma were related to the separation of the Yilgarn craton and the Napier Complex, respectively, to form a proto-Indo-Antarctic ocean and the Cuddapah basin. The proto-ocean was closed ~1650 Ma by the collision of the Lambert Terrane of East Antarctica and the Bastar-Dharwar craton. This collision, associated with ultra-high temperature (UHT) granulite facies metamorphism, is identified in the southern domain of the Eastern Ghats and the Oygardens domain of East Antarctica. The third extensional event between 1500 and 1200 Ma was associated with the separation of the Vestfold Hills block and a second phase of opening of the proto-Indian ocean, and the development of a series of basins on the western side of the Eastern Ghats (the Chhatisgarh, Khariar, Ampani, Indravati, and Sabari basins). The closing of this ocean basin during the Eastern Ghats-Rayner orogeny at ~950 Ma was related to the amalgamation of India and East Antarctica to form the supercontinent Rodinia. During the Neoproterozoic, this part of Rodinia was involved in orogenic collapse/extension and deposition of the Sodruzhesvo Group. The Pan-African Prydz Bay orogeny at ~550 Ma caused the closing of the basin to form East Gondwanaland.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
ABSTRACT The disk mass is among the most important input parameter for every planet formation model to determine the number and masses of the planets that can form. We present an ALMA 887 m survey of ...the disk population around objects from ∼2 to 0.03 M in the nearby ∼2 Myr old Chamaeleon I star-forming region. We detect thermal dust emission from 66 out of 93 disks, spatially resolve 34 of them, and identify two disks with large dust cavities of about 45 au in radius. Assuming isothermal and optically thin emission, we convert the 887 m flux densities into dust disk masses, hereafter Mdust. We find that the relation is steeper than linear and of the form Mdust ∝ (M*)1.3-1.9, where the range in the power-law index reflects two extremes of the possible relation between the average dust temperature and stellar luminosity. By reanalyzing all millimeter data available for nearby regions in a self-consistent way, we show that the 1-3 Myr old regions of Taurus, Lupus, and Chamaeleon I share the same relation, while the 10 Myr old Upper Sco association has a steeper relation. Theoretical models of grain growth, drift, and fragmentation reproduce this trend and suggest that disks are in the fragmentation-limited regime. In this regime millimeter grains will be located closer in around lower-mass stars, a prediction that can be tested with deeper and higher spatial resolution ALMA observations.
The discovery by the IceCube experiment of a high-energy astrophysical neutrino flux with energies of the order of PeV, has opened new scenarios in astroparticles physics. A possibility to explain ...this phenomenon is to consider the minimal models of Dark Matter (DM) decay, the 4-dimensional operator
∼
y
α
χ
L
L
α
¯
H
χ
, which is also able to generate the correct abundance of DM in the Universe. Assuming that the cosmological background evolves according to the standard cosmological model, it follows that the rate of DM decay
Γ
χ
∼
|
y
α
χ
|
2
needed to get the correct DM relic abundance (
Γ
χ
∼
10
-
58
) differs by many orders of magnitude with respect that one needed to explain the IceCube data (
Γ
χ
∼
10
-
25
), making the four-dimensional operator unsuitable. In this paper we show that assuming that the early Universe evolution is governed by a modified cosmology, the discrepancy between the two the DM decay rates can be reconciled, and both the IceCube neutrino rate and relic density can be explained in a minimal model.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A detailed examination of lithostratigraphic, tectonothermal, geochronologic and palaeomagnetic database of the Dharwar–Bastar cratons of South India, the Yilgarn craton of Western Australia and the ...East Antarctic shield has shown broad similarity. Two palaeomagnetic key poles of ~
2400
Ma age from the Dharwar and Yilgarn cratons suggest near neighbor positions. Matching patterns of craton outlines, orientation of mafic dyke swarms and palaeo–north direction for ~
2400
Ma have established a continental assembly of “SIWA”, an acronym for South India (SI) and Western Australia (WA), at ~
2400
Ma. In this assembly the Yilgarn craton fits against the Bastar craton and the Singhbhum craton. The available geological data from the Napier Complex of the Eastern Antarctica and the Dharwar craton of South India were used to prepare the barcode style reconstruction of Archaean tectonostratigraphic events of both the cratons. The method of matching continental outlines, the internal features of two continental blocks and the palaeomagnetic data demonstrate that the Napier Complex was also a part of “SIWA” during the period 2200–1900
Ma and was located at the position of the Cuddapah basin of India adjacent to the Dharwar craton and the Yilgarn craton. The separation of the Napier Complex from the south Indian block led to the development of the Cuddapah basin at ~
1950
Ma.
Display omitted
► Proposed reconstruction of Southern India–Western Australia at ~
2400
Ma (“SIWA”). ► The Napier Complex of Antarctica was a part of “SIWA” till 1950
Ma. ► The Cuddapah basin formed by separation of the Napier Complex from the Dharwar craton.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The Satpura Mountain Belt (also referred as Central Indian Tectonic Zone in recent literature) forms an important morphotectonic unit in the central part of India. Some of the recent workers have ...reported an orogenic event at ∼1000–900
Ma (termed “Sausar orogeny”) which led to amalgamation of the North Indian Block and the South Indian Block and formation of the Satpura Mountain Belt. In this model the stratigraphic relations of two important lithostratigraphic units on either side of the Satpura Mountain Belt (the Sausar Group in the south and the Vindhyan Supergroup on the north) are suggested to be revised from previously held ideas. Critical analyses of available published work in the region to assess the status of the Sausar Group
vis a vis the Vindhyan Supergroup was carried out. It is found that the ideas proposed by the recent workers stem from an earlier interpretation that the Sausar Group has monocyclic evolution and the earliest fabric in the Sausar Group is marked by a schistosity with EW strike. Re-mapping of the gneissic rocks and adjacent matasedimentary rocks of Khawasa, Deolapar, and Kandri–Mansar areas revealed presence of gneissic rocks and granulites of two generations, and of four phases of superposed deformations in the metasediments and gneisses. The older gneisses and granulites constitute the basement over which the rocks of the Sausar Group were deposited; and the younger gneisses developed by metamorphism and migmatisation of the rocks of the Sausar Group. The latter types are found in the Khawasa–Ramakona areas. Contrary to the belief of the recent workers that no volcanic activity is present in the Sausar Group, volcanic rocks marked by amygdular basic flows and tuffs have been mapped from different parts of the Sausar Group. Migmatisation and metamorphism of these volcanic rocks (of the Sausar Group) have given rise to amphibolites and granulites in Khawasa and Ramakona areas. Therefore, the use of fabric patterns in these areas to suggest that the granulite facies metamorphism in the Ramakona–Katangi granulite domain was pre-Sausar in age is debatable.
Available geochronological data of the Satpura Mountain Belt and its eastward continuation into the Chhotanagpur Gneiss terrain indicate that the basement and cover rocks of these areas were subjected to multiple deformation and metamorphic episodes of similar style and nature. The earliest deformation and metamorphism of the rocks of the Sausar Group and its equivalent rocks to the east took place at ∼2100–1900
Ma. The regional EW trend of the belt developed during the second deformation at ∼1800–1700
Ma and again at ∼1600–1500
Ma. This deformation was accompanied by migmatisation and granulite facies metamorphism in the northern domain of the Sausar Belt and in the Chhotanagpur Gneiss region. Late phase low intensity deformations in the region were associated with thermal events at ∼1100–1000
Ma and ∼900–800
Ma.
The ∼EW trending fabric, referred as “Satpura orogenic trend” in Indian literature marks a major compressional tectonic event, developed during the second deformation of the Sausar Group. This has its counter part in Western Australia as the Capricorn orogeny (∼1780–1830
Ma). The development of the Satpura Mountain Belt during the Grenvillian orogeny is ruled out from the synthesis of event stratigraphic data of the region and from its comparison with the Western Australian Craton.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Phase formation, microstructural evolution and the mechanical properties of novel multi-component equiatomic AlCoCrFeNi high entropy alloy synthesized by high energy ball milling followed by spark ...plasma sintering have been reported here. The microstructure of the mechanically alloyed (MA) powder and sintered samples were studied using X-ray diffraction, scanning electron and transmission electron microscopy, whereas the detailed investigation of the mechanical properties of the sintered samples were measured using micro and nano hardness techniques. The fracture toughness measurements were performed by applying single edge V notch beam (SEVNB) technique. The MA powder shows the presence of FCC (τ) and BCC (κ) solid solution phases. Extended ball milling (up to 60h) does not change the phases present in MA powder. The sintered pellets show phase-separated microstructure consisting of Al-Ni rich L12 phase, α′ and tetragonal Cr-Fe-Co based σ phase along with Al-Ni-Co-Fe FCC solid solution phase (ε) for sample sintered from 973 to 1273K. The experimental evidences indicate that BCC (κ) solid solution undergoes eutectoid transformation during sintering leading to the formation of L12 ordered α′ and σ phases, whereas FCC (τ) phase remains unaltered with a slight change in the lattice parameter. The hardness of the sample increases with sintering temperature and a sudden rise in hardness is observed 1173K. The sample sintered at 1273K shows the highest hardness of ~8GPa. The elastic modulus mapping clearly indicates the presence of three phases having elastic moduli of about 300, 220 and 160GPa. The fracture toughness obtained using SEVNB test shows a maximum value of 3.9MPam1/2, which is attributed to the presence of brittle nanosized σ phase precipitates. It is proposed that significant increase in the fraction of σ phase precipitates and eutectoid transformation of the τ phase contribute to increase in hardness along with better densification at higher sintering temperatures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Reconstruction of the Neoproterozoic supercontinent Rodinia shows near neighbour positions of the South Indian Cratons and Western Australian Cratons. These cratonic areas are characterized by ...extensive Paleoproterozoic tectonism. Detailed analysis of the spatio-temporal data of the Satpura Mountains of India indicates presence of at least three episodes of Proterozoic orogeny at ~ 2100-1900 Ma, ~ 1850 Ma and ~ 1650 Ma, and associated basin development and closing. A subdued imprint of the Grenville orogeny （~ 950 Ma） is also found in rock records of this Mountain Belt. The Capricorn Orogen of Western Australia also shows three episodes of orogeny： Opthalmian-Glenburgh Orogeny （2100-1950 Ma）, Capricorn Orogeny （ ~ 1800 Ma） and Mangaroon Orogeny （ ~ 1650 Ma）, and basin opening and closing related to these tectonic movements. These broad similarities suggest their joint evolution possibly in a near neighbour posi- tion during Paleoproterozoic Era. In view of juxtaposition of the Western Australia along the east coast of India, at the position of the Eastern Ghats, during Archean, it is suggested that the breaking of this Archean megacraton at - 2400 Ma led to northward movement of the broken components and formation of the Satpura-Capricorn Orogen （at - 2100 and - 1800 Ma） due to the collision of cratonic blocks with the pre- existing northern cratonic nuclei of India and Western Australia. This is also the time of formation of thesupercontinent Columbia. A phase of basin opening followed the ~ 1800 Ma event, followed by another phase of collisional event at - 1600 Ma at the site of the Satpura--Capricorn Orogen. Subsequent evolutions of the Satpura and the Capricorn Orogens differ slightly, indicating separate evolutional history.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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