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91.
Corrosion behavior of mild steel plain bar embedded in concrete with 28 days compressive strength of 40 N/mm2 exposed to natural marine environment at a location in the Gulf of Mannar was studied. This paper reports the results of 1-year study conducted on the reinforced concrete specimens exposed to three different levels. The performance of three different types of corrosion protection by specialty coatings to rebars, namely cement polymer composite, interpenetrating polymer network coating and epoxy coating was also evaluated periodically by measuring open circuit potential measurements and the results are discussed. Biofouling was predominant on completion of 3 months immersion. 相似文献
92.
A. Sequeira H. Rajagopal I. K. Gopalakrishnan J. V. Yakhmi R. M. Iyer 《Journal of Superconductivity》1993,6(4):265-272
The structures of A: YBa2Cu4O8 (T
c=80 K), B: Y0.9Ce0.1Ba2Cu4O8 (T
c=5K), and C: YBa2.2Cu4O8 (T
c=80 K) have been investigated using the powder neutron technique with a view to assessing the influence of the bridging Cu(2)-O(4) and Cu(1)-O(4) bonds on the superconducting transition temperature. The Cu(2)-O(4) bond for samples A and C (withT
c=80 K) appears to be compressed as compared to the reported data. On the other hand, the substitution of Ce at 10% Y sites elongates the Cu(2)-O(4) bond substantially and also brings theT
cdown to 55 K. The role of Cu(2)-O(4) bond length as well as other parameters expected to influence theT
cbehavior of Y-124 samples are discussed in the light of the present data. The study also shows that the ambient oxygen pressure route, if tried with the starting composition YBa2.2Cu4O
y
, leads to a quite homogeneous 124-phase. 相似文献
93.
Maria J. Muthuiah Jibu Thomas Rajagopal Raj Kumar & Abul K. Azad Mandal 《International Journal of Food Science & Technology》2009,44(10):2070-2074
Green tea is proved to be a source of various biochemicals, which projects tea to be a health drink. The study investigated free radical scavenging activity of leaf extracts of south Indian tea clones, individual catechin molecules and documented the influence of various additives on the scavenging activity of black tea infusion. Among the tea clones, UPASI-17 contained higher quantum of catechins. Lower content of catechins correlated with low 1,1-diphenyl-2-picrylhydrazyl and hydroxyl scavenging activities. Low scavenging activity was noticed in gallocatechin. A wide variation was found in free radical scavenging activity of individual molecules, leaf extracts, tea liquor and its combination with the additives. Tea liquor along with lemon juice showed the highest free radical scavenging activity. When sugar and lemon juice were amended with tea liquor, free radical scavenging activity declined marginally. Addition of milk and sugar with tea liquor declined the free radical scavenging activity significantly. 相似文献
94.
R. Rodrigues Coelho I. Hovell E. Lopez Moreno A. Lopes de Souza K. Rajagopal 《Petroleum Science and Technology》2007,25(1):41-54
Asphaltenes are components of crude oil, and their average chemical structures are characterized with difficulty. This study shows that simple Fourier transform infrared (FTIR) analysis spectroscopy could be adapted to the determination of aromatic hydrogens in asphaltenes and resins and elucidation of their average molecules. The work demonstrates the existence of a linear correlation in the infrared (IR) intensities of the symmetric and asymmetric aromatic hydrogens in methyl substituted arenes, in the 2,900 to 3,100 cm-1 region and of the out-of-plane deformation in the 700 to 900 cm-1 region. 相似文献
95.
N. Koch E. Zojer A. Rajagopal J. Ghjisen R. L. Johnson G. Leising J.‐J. Pireaux 《Advanced functional materials》2001,11(1):51-58
Ultraviolet photoelectron spectroscopy was used to determine the energy level alignment at the interfaces formed by either the deposition of para‐sexiphenyl (6P) onto samarium thin films, or by growing samarium on 6P films. We find that for both cases (6P on Sm, and Sm on 6P) the interaction at the interface is weak (physisorption), and the interfacial dipole is smaller than 0.2 eV. This weak interaction enabled us to demonstrate that small morphological changes in the substrate Sm film lead to a reversal in the direction of the interfacial dipole. For native silicon oxide substrates the appearance of a photoemission signal more than 1 eV above the Fermi level is observed, and explained by the energy level alignment process for wide bandgap organic semiconductors. Additionally, we demonstrate that large lateral vacuum level shifts (ca. 1 eV) can be locally realized on an inhomogeneous sample. 相似文献
96.
Zhibin Yang Adharsh Rajagopal Alex K.‐Y. Jen 《Advanced materials (Deerfield Beach, Fla.)》2017,29(47)
Extremely high power conversion efficiencies (PCEs) of ≈20–22% are realized through intensive research and development of 1.5–1.6 eV bandgap perovskite absorbers. However, development of ideal bandgap (1.3–1.4 eV) absorbers is pivotal to further improve PCE of single junction perovskite solar cells (PVSCs) because of a better balance between absorption loss of sub‐bandgap photons and thermalization loss of above‐bandgap photons as demonstrated by the Shockley–Queisser detailed balanced calculation. Ideal bandgap PVSCs are currently hindered by the poor optoelectronic quality of perovskite absorbers and their PCEs have stagnated at <15%. In this work, through systematic photoluminescence and photovoltaic analysis, a new ideal bandgap (1.35 eV) absorber composition (MAPb0.5Sn0.5(I0.8Br0.2)3) is rationally designed and developed, which possesses lower nonradiative recombination states, band edge disorder, and Urbach energy coupled with a higher absorption coefficient, which yields a reduced Voc,loss (0.45 V) and improved PCE (as high as 17.63%) for the derived PVSCs. This work provides a promising platform for unleashing the complete potential of ideal bandgap PVSCs and prospects for further improvement. 相似文献
97.
V. Rajagopal Reddy M. Siva Pratap ReddyA. Ashok Kumar Chel-Jong Choi 《Thin solid films》2012,520(17):5715-5721
In the present work, thin film of polyvinyl alcohol (PVA) is fabricated on n-type InP substrate as an interfacial layer for electronic modification of Au/n-InP Schottky contact. The electrical characteristics of Au/PVA/n-InP Schottky diode are determined at annealing temperature in the range of 100-300 °C by current-voltage (I-V) and capacitance-voltage (C-V) methods. The Schottky barrier height and ideality factor (n) values of the as-deposited Au/PVA/n-InP diode are obtained at room temperature as 0.66 eV (I-V), 0.82 eV (C-V) and 1.32, respectively. Upon annealing at 200 °C in nitrogen atmosphere for 1 min, the barrier height value increases to 0.81 eV (I-V), 0.99 eV (C-V) and ideality factor decreases to 1.18. When the contact is annealed at 300 °C, the barrier height value decreases to 0.77 eV (I-V), 0.96 eV (C-V) and ideality factor increases to 1.22. It is observed that the interfacial layer of PVA increases the barrier height by the influence of the space charge region of the Au/n-InP Schottky junction. The discrepancy between Schottky barrier heights calculated from I-V and C-V measurements is also explained. Further, Cheung's functions are used to extract the series resistance of Au/PVA/n-InP Schottky diode. The interface state density as determined by Terman's method is found to be 1.04 × 1012 and 0.59 × 1012 cm− 2 eV− 1 for the as-deposited and 200 °C annealed Au/PVA/n-InP Schottky diodes. Finally, it is seen that the Schottky diode parameters changed with increase in the annealing temperature. 相似文献
98.
Sorption of lead, mercury and cadmium ions in multi-component system using carbon aerogel as adsorbent 总被引:2,自引:0,他引:2
In the present study, adsorption of three metal ions Pb(II), Hg(II) and Cd(II) on carbon aerogel a new form of activated carbon has been investigated in mono- and multi-component (binary and tertiary) system. Batch experiments were also carried out for mono- and multi-component systems with varying metal ion concentration (mg/l) to investigate the competitive adsorption characteristics. Many adsorbents have been studied for their adsorption properties pertaining to mono-component solutions of metal ions. However, to treat wastewater with new materials, their performance needs to be ascertained in multi-component system. The scanning electron micrographs (SEM) and EDAX spectrum of carbon aerogel surfaces before and after the adsorbent was equilibrated with the metal ion solution clearly establishes the presence of the metal ions and some surface modifications can be observed on the carbon aerogel particles adsorption with (i) surface chemistry of the pellets on the surface of carbon aerogel and (ii) inside layers of the carbon aerogel. Applicability of the isotherm models namely Freundlich and Langmuir to predict the equilibrium uptake of Pb(II), Hg(II) and Cd(II) in mono-component, binary and tertiary system has also been tested. Langmuir and Freundlich models are found to generally represent the experimental though but not consistently. 相似文献
99.
100.