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121.
A. P. Godbole M. V. Koutras F. S. Milienos 《Annals of the Institute of Statistical Mathematics》2011,63(3):559-584
A k × n array with entries from a q-letter alphabet is called a t-covering array if each t × n submatrix contains amongst its columns each one of the q
t
different words of length t that can be produced by the q letters. In the present article we use a probabilistic approach based on an appropriate Markov chain embedding technique,
to study a t-covering problem where, instead of looking at all possible t × n submatrices, we consider only submatrices of dimension t × n with its rows being consecutive rows of the original k × n array. Moreover, an exact formula is established for the probability distribution function of the random variable, which
enumerates the number of deficient submatrices (i.e., submatrices with at least one missing word, amongst their columns),
in the case of a k × n binary matrix (q = 2) obtained by realizing kn Bernoulli variables. 相似文献
122.
Chauhan N Gupta S Singh N Singh S Islam SS Sood KN Pasricha R 《Journal of colloid and interface science》2011,363(1):42-50
We depict a novel strategy exploiting the chemistry of metal ion adsorption for detection and sequestration of toxic heavy metal from processed water using gold nanoparticles capped with 4-aminothiophenol. The interaction between 4-aminothiophenol capped gold nanoparticles and heavy metal ions was studied as a function of time and concentration using TEM, HRTEM, SEM, EDS, and I-V characterization. Experiments confirmed that pH is one of the crucial controlling parameters. Adsorption capacity was monitored using AAS, UV-vis spectroscopy and I-V measurement. In the absence of any alloy formation between Au and heavy metal ions, the desorption of the heavy metal ions from 4-aminothiophenol capped gold nanoparticles surface by pH modulation serves as a mean of collection of heavy metal ions. Experiments revealed that the concentration of heavy metal ions in processed water after adsorption is below the maximum permissible limit set by the WHO. 相似文献
123.
We compute analytically the full distribution of Andreev conductance G(NS) of a metal-superconductor interface with a large number N(c) of transverse modes, using a random matrix approach. The probability distribution P(G(NS),N(c) in the limit of large N(c) displays a Gaussian behavior near the average value =(2-√2)N(c) and asymmetric power-law tails in the two limits of very small and very large G(NS). In addition, we find a novel third regime sandwiched between the central Gaussian peak and the power-law tail for large G(NS). Weakly nonanalytic points separate these four regimes-these are shown to be consequences of three phase transitions in an associated Coulomb gas problem. 相似文献
124.
M. Mohapatra R.M. KadamR.K. Mishra C.P. KaushikB.S. Tomar S.V. Godbole 《Physica B: Condensed Matter》2011,406(20):3980-3984
Gamma radiation induced changes were investigated in sodium-barium borosilicate glasses containing Eu. The glass composition was similar to that of nuclear waste glasses used for vitrifying Trombay research reactor nuclear waste at Bhabha Atomic Research Centre, India. Photoluminescence (PL) and electron paramagnetic resonance (EPR) techniques were used to study the speciation of the rare earth (RE) ion in the matrix before and after gamma irradiation. Judd-Ofelt (J-O) analyses of the emission spectra were done before and after irradiation. The spin counting technique was employed to quantify the number of defect centres formed in the glass at the highest gamma dose studied. PL data suggested the stabilisation of the trivalent RE ion in the borosilicate glass matrix both before and after irradiation. It was also observed that, the RE ion distributes itself in two different environments in the irradiated glass. From the EPR data it was observed that, boron oxygen hole centre based radicals are the predominant defect centres produced in the glass after irradiation along with small amount of E’ centres. From the spin counting studies the concentration of defect centres in the glass was calculated to be 350 ppm at 900 kGy. This indicated the fact that bulk of the glass remained unaffected after gamma irradiation up to 900 kGy. 相似文献
125.
The projection of integrating optical, magnetic and electronic functionalities into a single material have aggravated passionate
attention in mounting wide band gap diluted magnetic semiconductor (DMS) in the midst of room temperature ferromagnetism.
We report the evidence of ferromagnetism in Cu-doped ZnSe quantum dots (QDs) below room temperature, grown from a single source
precursor by lyothermal method with the sizes of approximately 3.2–5.14 nm. QDs mainly exhibit paramagnetic behavior between
80 and 300 K, with a weak ferromagnetic/anti-ferromagnetic exchange at lower temperature as observed by superconducting quantum
interference device (SQUID) magnetometer. From the Curie–Weiss behavior of the susceptibility, Curie temperature (T
c) of Cu-doped ZnSe sample has been evaluated. From EPR, we obtain the Lande-g factor in the Zeeman interaction term as 2.060. Photoluminescence and EPR measurements support and confirm the view that
Cu2+ substitutes for Zn2+ in Cu-doped ZnSe quantum dots. 相似文献
126.
Punita Srivastava Pushpendra Kumar Kedar Singh 《Journal of nanoparticle research》2011,13(10):5077-5085
Manipulation of carrier spins in semiconductors for spintronics applications has received great attention driven by improved
functionalities and higher speed operation. Doping of semiconductor nanocrystals by transition-metal ions pronounced as diluted
magnetic semiconductors (DMS) has attracted tremendous attention. Such doping is, however, difficult to achieve in low-dimensional
strongly quantum-confined nanostructures by conventional growth procedures. In the present case, magic-sized, pure, and Cr-doped
CdS DM-QDs have been synthesized by solution phase chemistry (lyothermal method). Structural, optical, and magnetic investigation
suggest an intrinsic nature of ferromagnetism with highly quantum-confined system. Optical and magnetic results of pure and
doped QDs reveal major physical consequences of dopant localization within the capacity to engineer dopant-carrier exchange
interactions introducing magnetic functionalities within the host semiconductor lattice. Unpaired Cr ions in Cd substitutional
sites could create spin ordering and ferromagnetic coupling. The results presented herein illustrate some of the remarkable
and unexpected complexities that can arise in doped QDs. 相似文献
127.
A new technology, called electro-chemical residue sensor (ECRS), has been developed for the in situ and real-time measurement of the residual impurities left on the wafer surface and in the fine structures of patterned wafers during typical rinse processes. The key components of this technology, which consist of the sensor hardware and a process model, are described. The testing results of the ECRS show that the residual impurity concentration is significantly different from what is typically provided by the bulk water resistivity, which is usually employed for determining the progress of the rinse. As a case study, the new metrology method has been applied to the removal of sulfate ions from patterned wafers; the importance of various surface interactions, charge effects, and transport processes is determined. Two examples of the use of the ECRS for the development of novel rinse recipes to reduce water usage are also discussed. 相似文献
128.
Rohini M Godbole 《Pramana》2006,67(5):835-847
In this talk I discuss some aspects of CP violation (CPV) in supersymmetry (SUSY) as well as in the Higgs sector. Further,
I discuss ways in which these may be probed at hadronic colliders. In particular I will point out the ways in which studies
in the
sector at the Tevatron may be used to provide information on this and how the search can be extended to the LHC. I will then
follow this by a discussion of the CP mixing induced in the Higgs sector due to the above-mentioned CPV in the soft SUSY breaking
parameters and its effects on the Higgs phenomenology at the LHC. I would then point out some interesting aspects of the phenomenology
of a moderately light charged Higgs boson, consistent with the LEP constraints, in this scenario. Decay of such a charged
Higgs boson would also allow a probe of a light (≲50 GeV), CP-violating (CPV) Higgs boson. Such a light neutral Higgs boson
might have escaped detection at LEP and could also be missed at the LHC in the usual search channels. 相似文献
129.
Abhay D. Deshmukh S. J. Dhoble S. V. Godbole M. K. Bhide D. R. Peshwe 《Indian Journal of Physics》2009,83(4):423-428
The calcium aluminates doped with Eu ions, Ca5Al8O14: Eu, phosphors are prepared by the combustion method. The formation of crystalline aluminates was confirmed by X-ray diffraction
pattern. The prepared phosphors were characterized by SEM, TGA, DTA, particle size analyzer and Photoluminescence (PL) techniques.
From the UV-excited luminescence spectra it was found that the Eu ions acts as a luminescent centre with luminescence at the
blue (λ
max = 470 nm) region due to 4f
65d
1 → 4f
7 transition. The excitation spectra show the broad band at 355 nm wavelength (λ
em = 470 nm). The excitation 355 nm is a mercury free excitation and therefore Ca5Al8O14: Eu may be useful for the solid state lighting phosphor in lamp industry.
相似文献
130.
Bhupal Dev PS Djouadi A Godbole RM Mühlleitner MM Rindani SD 《Physical review letters》2008,100(5):051801
The search and the probe of the fundamental properties of Higgs boson(s) and, in particular, the determination of their charge conjugation and parity (CP) quantum numbers, are the main tasks of future high-energy colliders. We demonstrate that the CP properties of a standard model-like Higgs particle can be unambiguously assessed by measuring just the total cross section and the top polarization in associated Higgs boson production with top quark pairs in e(+)e(-) collisions. 相似文献