195 research outputs found
Negative-Mode LDI-MS of corrosion products on the surface of AgCu-X (X- Zn, Pd, In) alloys
Copper-silver alloys have widely applied in many different areas such as information and communication technology, rail transportation, power transmission lines, microelectronics, machinery manufacturing, chemical processing industries, coinage, ornamental parts, etc [1, 2]. A group of ternary Ag-Cu alloys with different elements is used for binding different materials (brazing, fillers, and pastes). For example, Ag-Cu-Pd alloys are used in dentistry, as amalgams improvers or joint fillers for different dental materials [3]. Ternary AgCuIn alloy uses as a bonding metal layer; the use of AgCuIn as the bonding metal, greatly reduces the manufacturing costs of LED chip and helps to improve the life of the LED chip. Copper and its alloys belong to the group of semi-noble metals however they are not highly resistant to corrosion in some of the environments [4, 5]. Corrosion has particularly attracted attention due to the significant impact on the performance and reliability of this industrially important material group in their applications, as well as on the economy. Standard methods for characterization of corrosion films are: X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM) with Energy Dispersive Spectroscopy (EDS) [6, 7]. The positive mode laser desorption ionization (LDI) mass spectrometry method can be successfully applied to analyze the composition of the corrosion film. In our previous work, it has been shown that the amount of sample required for the LDI method is much smaller than the sample quantity required for the methods mentioned above [8]. The purpose of this work was to study the possibilities of direct analysis of the corrosion films formed on Ag60Cu26Zn14, Ag58.5Cu31.5Pd10, and Ag63Cu27In10 alloys using the negative mode laser desorption ionization (LDI) mass spectrometry method. The corrosion films of Ag60Cu26Zn14, Ag58.5Cu31.5Pd10, and Ag63Cu27In10 alloys were obtained after anodic potentiostatic polarization treatment (at +0.25 V for 5 min in 3.5% wt. NaCl solution). Preliminary results show that the negative mode LDI mass spectra measured from the corrosion film of these alloys contains same ionsAgCl2 - , AgCuCl3 - , CuCl2 - , Cu2Cl3 - , Cu3Cl4 - . This result suggested that main reactions are the formation of CuCl layer on the surface of the Cu rich metallurgical phase and formation of AgCl film on the surface of Ag rich metallurgical phase. ACKNOWLEDGEMENT: This work is the result of the Projects OI 172019 and TR 34033, funded by the Ministry of Education, Science and Technological Development of the Republic of Serbia.VII International School and Conference on Photonics : PHOTONICA2019 : Abstracts of Tutorial, Keynote, Invited Lectures, Progress Reports and Contributed Papers; August 26-30; Belgrad
Differential structure on kappa-Minkowski space, and kappa-Poincare algebra
We construct realizations of the generators of the -Minkowski space
and -Poincar\'{e} algebra as formal power series in the -adic
extension of the Weyl algebra. The Hopf algebra structure of the
-Poincar\'{e} algebra related to different realizations is given. We
construct realizations of the exterior derivative and one-forms, and define a
differential calculus on -Minkowski space which is compatible with the
action of the Lorentz algebra. In contrast to the conventional bicovariant
calculus, the space of one-forms has the same dimension as the
-Minkowski space.Comment: 20 pages. Accepted for publication in International Journal of Modern
Physics
Smart capacitive moisture sensor calibration in mineral wool and green roof soil substrate
The environmental benefits of green roofs have been widely recognized. In recent years, increasing attention has been paid to moisture management in the green roof systems. The moisture in the green roof has an influence on its thermal and hydrological performances. An accurate measurement of water content in green roof substrate is important for irrigation monitoring, optimal irrigation management, and plant growth. Knowing the performance and characteristics of the sensor for the chosen substrate layer in a green roof system is essential. This paper presents laboratory calibration of the capacitive moisture sensor in two types of the green roof substrate layer. The volumetric water content of several mineral wool and soil samples, with the water content from low until saturated, were measured using the gravimetric method and related to frequency obtained by the sensor. The results have shown that the capacitive moisture sensor has a good response to water content variation
Covariant realizations of kappa-deformed space
We study a Lie algebra type -deformed space with undeformed rotation
algebra and commutative vector-like Dirac derivatives in a covariant way. Space
deformation depends on an arbitrary vector. Infinitely many covariant
realizations in terms of commuting coordinates of undeformed space and their
derivatives are constructed. The corresponding coproducts and star products are
found and related in a new way. All covariant realizations are physically
equivalent. Specially, a few simple realizations are found and discussed. The
scalar fields, invariants and the notion of invariant integration is discussed
in the natural realization.Comment: 31 pages, no figures, LaTe
Non-LTE calculations for neutral Na in late-type stars using improved atomic data
Neutral sodium is a minority species in the atmospheres of late-type stars,
and line formation in local thermodynamic equilibrium (LTE) is often a poor
assumption, in particular for strong lines. We present an extensive grid of
non-LTE calculations for several NaI lines in cool stellar atmospheres,
including metal-rich and metal-poor dwarfs and giants. For the first time, we
constructed a Na model atom that incorporates accurate quantum mechanical
calculations for collisional excitation and ionisation by electrons as well as
collisional excitation and charge exchange reactions with neutral hydrogen.
Similar to LiI, the new rates for hydrogen impact excitation do not affect the
statistical equilibrium calculations, while charge exchange reactions have a
small but non-negligible influence. The presented LTE and non-LTE
curves-of-growth can be interpolated to obtain non-LTE abundances and abundance
corrections for arbitrary stellar parameter combinations and line strengths.
The typical corrections for weak lines are -0.1...-0.2dex, whereas saturated
lines may overestimate the abundance in LTE by more than 0.5dex. The non-LTE Na
abundances appear very robust with respect to uncertainties in the input
collisional data.Comment: 9 pages, 8 figures, accepted for publication in A&
A twisted look on kappa-Minkowski: U(1) gauge theory
Kappa-Minkowski space-time is an example of noncommutative space-time with
potentially interesting phenomenological consequences. However, the
construction of field theories on this space, although operationally
well-defined, is plagued with ambiguities. A part of ambiguities can be
resolved by clarifying the geometrical picture of gauge transformations on the
kappa-Minkowski space-time. To this end we use the twist approach to construct
the noncommutative U(1) gauge theory coupled to fermions. However, in this
approach we cannot maintain the kappa-Poincar\'e symmetry; the corresponding
symmetry of the twisted kappa-Minkowski space is the twisted igl(1,3) symmetry.
We construct an action for the gauge and matter fields in a geometric way, as
an integral of a maximal form. We use the Seiberg-Witten map to relate
noncommutative and commutative degrees of freedom and expand the action to
obtain the first order corrections in the deformation parameter.Comment: 24 pages, clarifications added, reference list updated, to appear in
JHE
Noncommutative Differential Forms on the kappa-deformed Space
We construct a differential algebra of forms on the kappa-deformed space. For
a given realization of the noncommutative coordinates as formal power series in
the Weyl algebra we find an infinite family of one-forms and nilpotent exterior
derivatives. We derive explicit expressions for the exterior derivative and
one-forms in covariant and noncovariant realizations. We also introduce
higher-order forms and show that the exterior derivative satisfies the graded
Leibniz rule. The differential forms are generally not graded-commutative, but
they satisfy the graded Jacobi identity. We also consider the star-product of
classical differential forms. The star-product is well-defined if the
commutator between the noncommutative coordinates and one-forms is closed in
the space of one-forms alone. In addition, we show that in certain realizations
the exterior derivative acting on the star-product satisfies the undeformed
Leibniz rule.Comment: to appear in J. Phys. A: Math. Theo
Scalar field propagation in the phi^4 kappa-Minkowski model
In this article we use the noncommutative (NC) kappa-Minkowski phi^4 model
based on the kappa-deformed star product, ({*}_h). The action is modified by
expanding up to linear order in the kappa-deformation parameter a, producing an
effective model on commutative spacetime. For the computation of the tadpole
diagram contributions to the scalar field propagation/self-energy, we
anticipate that statistics on the kappa-Minkowski is specifically
kappa-deformed. Thus our prescription in fact represents hybrid approach
between standard quantum field theory (QFT) and NCQFT on the kappa-deformed
Minkowski spacetime, resulting in a kappa-effective model. The propagation is
analyzed in the framework of the two-point Green's function for low,
intermediate, and for the Planckian propagation energies, respectively.
Semiclassical/hybrid behavior of the first order quantum correction do show up
due to the kappa-deformed momentum conservation law. For low energies, the
dependence of the tadpole contribution on the deformation parameter a drops out
completely, while for Planckian energies, it tends to a fixed finite value. The
mass term of the scalar field is shifted and these shifts are very different at
different propagation energies. At the Planckian energies we obtain the
direction dependent kappa-modified dispersion relations. Thus our
kappa-effective model for the massive scalar field shows a birefringence
effect.Comment: 23 pages, 2 figures; To be published in JHEP. Minor typos corrected.
Shorter version of the paper arXiv:1107.236
Stark Broadening of the B III 2s-2p Lines
We present a quantum-mechanical calculation of Stark line widths from
electron-ion collisions for the , lambda = 2066 and 2067
A, resonance transitions in B III. The results confirm the previous
quantum-mechanical R-matrix calculations but contradict recent measurements and
semi-classical and some semi-empirical calculations. The differences between
the calculations can be attributed to the dominance of small L partial waves in
the electron-atom scattering, while the large Stark widths inferred from the
measurements would be substantially reduced if allowance is made for
hydrodynamic turbulence from high Reynolds number flows and the associated
Doppler broadening.Comment: 21 pages, 4 figures; to be published in Phys. Rev.
N=1/2 Deformations of Chiral Superspaces from New Quantum Poincare and Euclidean Superalgebras
We present a large class of supersymmetric classical r-matrices, describing
the supertwist deformations of Poincare and Euclidean superalgebras. We
consider in detail new family of four supertwists of N=1 Poincare superalgebra
and provide as well their Euclidean counterpart. The proposed supertwists are
better adjusted to the description of deformed D=4 Euclidean supersymmetries
with independent left-chiral and right-chiral supercharges. They lead to new
quantum superspaces, obtained by the superextension of twist deformations of
spacetime providing Lie-algebraic noncommutativity of space-time coordinates.
In the Hopf-algebraic Euclidean SUSY framework the considered supertwist
deformations provide an alternative to the N=1/2 SUSY Seiberg's star product
deformation scheme.Comment: 17 pages, LaTeX, new (re-worked) revised and extended versio
- …