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101.
E. C. Niculescu M. Cristea 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,84(1):59-67
By using the finite element method within the effective mass approximation, the effects
of both dielectric confinement and electric field on the shallow-donor binding energy and
polarizability in spherical Si quantum dots are investigated. It is found that: (i) the
ground state binding energy is significantly increased by the dielectric mismatch at the
dot interface, (ii) in the freestanding nanodot the competition between the electric
field, polarization charges induced at interfaces and impurity position determines the
symmetry of the electron probability distribution; (iii) the donor polarizability
decreases with electric field strength and this effect is more pronounced for large
dielectric mismatches. Therefore, the electronic properties of the nanocrystals could be
tuned by proper tailoring of the surrounding medium dielectric constant as well as by
varying the electric field. The normalized binding energy of an on-center hydrogenic donor
is also been estimated and the results are in good agreement with the previous reported
values. 相似文献
102.
Alexandru C. Razus Liviu Birzan Mihaela Cristea Victorita Tecuceanu Anamaria Hanganu Cristian Enache 《Journal of heterocyclic chemistry》2011,48(5):1019-1027
Pyranylium perchlorates with azulen‐1‐yl moiety in 4‐position and thiophen‐2‐yl or furan‐2‐yl in 2 and 6‐positions were obtained by the substitution of 4‐chloro corresponding salts with azulenes. The pyranylium salts are used as starting materials for the synthesis of pyridine and pyridinium salts. The products were characterized and for pyridines pKa was spectroscopically determined. Several attempts were made for pyridine complexation with metal cations as Hg2+ or Ag+. J. Heterocyclic Chem., (2011). 相似文献
103.
Different partial hypergroupoids are associated with binary relations defined on a set H. In this paper we find sufficient and necessary conditions for these hypergroupoids in order to be reduced hypergroups. Given two binary relations ρ and σ on H we investigate when the hypergroups associated with the relations ρ∩σ, ρ∪σ and ρσ are reduced. We also determine when the cartesian product of two hypergroupoids associated with a binary relation is a reduced hypergroup. 相似文献
104.
The concept of an HX-group is an upgrade of the concept of a group,in which a new operation is defined on the family of non-empty subsets of a group.If this new support set together with the new operation is a group,then we call it an HX-group.On the other hand,a hyperoperation is a mapping having the same codomain as the operation of an HX-group,i.e.,the family of non-empty subsets of the initial set,but a different domain-the set itself.This could be (and was indeed) a source of confusion,which is clarified in this paper.Moreover,HX-groups naturally lead to constructions of hypergroups.The links between these two algebraic concepts are presented,with the aim of reviving the old notion of an HX-group in the current research on algebraic hyperstructures.One of such existing links and one newly established link are also discussed. 相似文献
105.
This article presents a connection between fuzzy preordered structures and hyperstructures. Firstly, we introduce the notion of fuzzy preordered semigroup and then, we construct a semihypergroup associated with it, giving some properties of the associated hyperstructure. Secondly, we define the notion of fuzzy preordered ring in order to construct a fuzzy hyperring. 相似文献
106.
Luminiţa Fritea Mihaela Tertiş Cecilia Cristea Robert Săndulescu 《Electroanalysis》2023,35(1):e202200014
Cyclodextrins and nanomaterials are widely used in the achievement of powerful platforms in supramolecular chemistry and nanotechnology. The relatively hydrophobic internal cavity of the CDs selectively retains molecules having the proper geometry, while the hydrophilic exterior allows CDs to improve the dispersibility and molecular recognition. The nanomaterials provide higher surface area, good conductivity, and electrocatalytic effect. The use of nanomaterials and CDs in electrochemical sensors’ design allows the development of a large variety of devices, explaining the increasing number of papers in the last years that are discussed in this review. 相似文献