We consider a class of generalized derivations that arise in connection with the problem of adjoining unity to an algebra with generalized derivation, and of searching envelopes for Novikov–Poisson ...algebras. Conditions for the existence of the localization of an algebra with ternary derivation are specified, as well as conditions under which given an algebra with ternary derivation, we can construct a Novikov–Poisson algebra and a Jordan superalgebra. Finally, we show how the simplicity of an algebra with Brešar generalized derivation is connected with simplicity of the appropriate Novikov algebra.
We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of ...physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The synthesis of two parental BN anthracenes, 1 and 2, was developed, and their electronic structure and reactivity behavior were characterized in direct comparison with all-carbon anthracene. ...Gas-phase UV-photoelecton spectroscopy studies revealed the following HOMO energy trend: anthracene, −7.4 eV; BN anthracene 1, −7.7 eV; bis-BN anthracene 2, −8.0 eV. The λmax of the lower energy band in the UV–vis absorption spectrum is as follows: anthracene, 356 nm; BN anthracene 1, 359 nm; bis-BN anthracene 2, 357 nm. Thus, although the HOMO is stabilized with increasing BN incorporation, the HOMO–LUMO band gap remains unchanged across the anthracene series. The emission λmax values for the three investigated anthracene compounds are at 403 nm. The pK a values of the N-H proton for BN anthracene 1 and bis-BN anthracene 2 were determined to be approximately 26. BN anthracenes 1 and 2 do not undergo heat- or light-induced cycloaddition reactions or Friedel–Crafts acylations. Electrophilic bromination of BN anthracene 1 with Br2, however, occurs regioselectively at the 9-position. The reactivity behavior and regioselectivity of bromination of BN anthracenes are consistent with the electronic structure of these compounds; i.e., (1) the lower HOMO energy levels for BN anthracenes stabilize the molecules against cycloaddition and Friedel–Crafts reactions, and (2) the HOMO orbital coefficients are consistent with the observed bromination regioselectivity. Overall, this work demonstrates that BN/CC isosterism can be used as a molecular design strategy to stabilize the HOMO of acene-type structures while the optical band gap is maintained.
We study a two-dimensional (2-D) potential flow of an ideal fluid with a free surface with decaying conditions at infinity. By using the conformal variables approach, we study a particular solution ...of the Euler equations having a pair of square-root branch points in the conformal plane, and find that the analytic continuation of the fluid complex potential and conformal map define a flow in the entire complex plane, excluding a vertical cut between the branch points. The expanded domain is called the ‘virtual’ fluid, and it contains a vortex sheet whose dynamics is equivalent to the equations of motion posed at the free surface. The equations of fluid motion are analytically continued to both sides of the vertical branch cut (the vortex sheet), and additional time invariants associated with the topology of the conformal plane and Kelvin's theorem for a virtual fluid are explored. We called them ‘winding’ and virtual circulation. This result can be generalized to a system of many cuts connecting many branch points, resulting in a pair of invariants for each pair of branch points. We develop an asymptotic theory that shows how a solution originating from a single vertical cut forms a singularity at the free surface in infinite time, the rate of singularity approach is double exponential and supersedes the previous result of the short branch cut theory with finite time singularity formation. The present work offers a new look at fluid dynamics with a free surface by unifying the problem of motion of vortex sheets, and the problem of 2-D water waves. A particularly interesting question that arises in this context is whether instabilities of the virtual vortex sheet are related to breaking of steep ocean waves when gravity effects are included.
A very rich Fe-C phase diagram makes the formation of graphene on iron surfaces a challenging task. Here we demonstrate that the growth of graphene on epitaxial iron films can be realized by chemical ...vapor deposition at relatively low temperatures, and that the formation of carbides can be avoided in excess of the carbon-containing precursors. The resulting graphene monolayer creates a novel periodically corrugated pattern on Fe(110). Using low-energy electron microscopy and scanning tunneling microscopy, we show that it is modulated in one dimension forming long waves with a period of ∼4 nm parallel to the 001 direction of the substrate, with an additional height modulation along the wave crests. The observed topography of the graphene/Fe superstructure is well reproduced by density functional theory calculations, and found to result from a unique combination of the lattice mismatch and strong interfacial interaction, as probed by core-level photoemission and x-ray absorption spectroscopy.
We report the simultaneous measurement of the structural and electronic components of the metal-insulator transition (MIT) of VO2 using electron and photoelectron spectroscopies and microscopies. We ...show that these evolve over different temperature scales, and are separated by an unusual monocliniclike metallic phase. Our results provide conclusive evidence that the new monocliniclike metallic phase, recently identified in high-pressure and nonequilibrium measurements, is accessible in the thermodynamic transition at ambient pressure, and we discuss the implications of these observations on the nature of the MIT in VO2.
We survey recent results connected with constructing a new family of solutions of the Korteweg-de Vries equation, which we call primitive solutions. These solutions are constructed as limits of ...rapidly vanishing solutions of the Korteweg-de Vries equation as the number of solitons tends to infinity. A primitive solution is determined nonuniquely by a pair of positive functions on an interval on the imaginary axis and a function on the real axis determining the reflection coefficient. We show that elliptic one-gap solutions and, more generally, periodic finite-gap solutions are special cases of reflectionless primitive solutions.
The catalyst formation by reacting magnesium diethoxide with titanium tetrachloride in the presence of stereoregulating electron donor - di-n-butylphthalate (DBP) - is studied by sampling the ...intermediate products during catalyst synthesis. Chemical and phase composition, porous structure, activity and stereospecificity of these products are investigated. It is show that before DBP adding the X-ray amorphous product consisting of MgCl2 and TiCl3(OEt) is formed. This product has micro-mesoporous structure, very high surface area, but low activity and low stereospecificity. DBP has a significant effect on both the chemical composition of the catalyst due to removing inactive TiCl3(OEt), entering DBP and TiCl4 in solid product and formation of MgCl2 crystallites with mesoporous structure. At the same time the significant increase of the activity and stereospecificity is observed. Following TiCl4/chlorobenzene treatment of solid product completes these processes, provides some increasing the surface area at similar mesoporous structure and additionally increases activity and stereospecificity.
We address the problem of the potential motion of an ideal incompressible fluid with a free surface and infinite depth in a two-dimensional geometry. We admit the presence of gravity forces and ...surface tension. A time-dependent conformal mapping
$z(w,t)$
of the lower complex half-plane of the variable
$w$
into the area filled with fluid is performed with the real line of
$w$
mapped into the free fluid’s surface. We study the dynamics of singularities of both
$z(w,t)$
and the complex fluid potential
$\unicodeSTIX{x1D6F1}(w,t)$
in the upper complex half-plane of
$w$
. We show the existence of solutions with an arbitrary finite number
$N$
of complex poles in
$z_{w}(w,t)$
and
$\unicodeSTIX{x1D6F1}_{w}(w,t)$
which are the derivatives of
$z(w,t)$
and
$\unicodeSTIX{x1D6F1}(w,t)$
over
$w$
. We stress that these solutions are not purely rational because they generally have branch points at other positions of the upper complex half-plane. The orders of poles can be arbitrary for zero surface tension while all orders are even for non-zero surface tension. We find that the residues of
$z_{w}(w,t)$
at these
$N$
points are new, previously unknown, constants of motion, see also Zakharov & Dyachenko (2012, authors’ unpublished observations,
arXiv:1206.2046
) for the preliminary results. All these constants of motion commute with each other in the sense of the underlying Hamiltonian dynamics. In the absence of both gravity and surface tension, the residues of
$\unicodeSTIX{x1D6F1}_{w}(w,t)$
are also the constants of motion while non-zero gravity
$g$
ensures a trivial linear dependence of these residues on time. A Laurent series expansion of both
$z_{w}(w,t)$
and
$\unicodeSTIX{x1D6F1}_{w}(w,t)$
at each poles position reveals the existence of additional integrals of motion for poles of the second order. If all poles are simple then the number of independent real integrals of motion is
$4N$
for zero gravity and
$4N-1$
for non-zero gravity. For the second-order poles we found
$6N$
motion integrals for zero gravity and
$6N-1$
for non-zero gravity. We suggest that the existence of these non-trivial constants of motion provides an argument in support of the conjecture of complete integrability of free surface hydrodynamics in deep water. Analytical results are solidly supported by high precision numerics.
The approximate position of the Wuchiapingian–Changhsingian boundary of the Upper Permian in Northeast Russia was determined for the first time on the basis of the comparison of δ
13
С trends ...established in the sections of South China and Iran, the Tethyan Superrealm, and the Pautovaya River section (Kolyma–Omolon region, Boreal Superrealm). This boundary runs in the middle part of the Intomodesma costatum bivalve zone of the Khivachian regional horizon. This conclusion is also confirmed by the previous dating of zircons from a tuff layer below the Wuchiapingian–Changhsingian boundary in the same section and by
87
Sr/
86
Sr values from well-preserved brachiopod-spiriferid shells from the stratotypical section of the upper part of the Khivachian regional horizon on the Omolon massif.
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