Combined chiral dynamics and MIT bag model study of strong Σ<Superscript>(*)</Superscript><Subscript>Q</Subscript>→Λ<Subscript>Q</Subscript>π decays

The strong decays of the heavy baryons Σ^(*) _Q→Λ_Qπ are studied by combining the chiral dynamics and the MIT bag model. In the charm sector, we calculate the decay widths Γ(Σ^(*) _c→Λ_cπ) and compare these with the experimental data and other theoretical estimations. In addition, we also predict the strong decay widths Γ(Σ^(*) _b→Λ_bπ).     

The effects of hydrogen plasma pretreatment on the formation of vertically aligned carbon nanotubes

The effects of H₂ plasma pretreatment on the growth of vertically aligned carbon nanotubes (CNTs) by varying the flow rate of the precursor gas mixture during microwave plasma chemical vapor deposition (MPCVD) have been investigated in this study. Gas mixture of H₂ and CH₄ with a ratio of 9:1 was used as the precursor for synthesizing CNTs on Ni-coated TiN/Si(1 0 0) substrates. The structure and composition of Ni catalyst nanoparticles were investigated by using scanning electron microscopy (SEM) and cross-sectional transmission electron microscopy (XTEM). Results indicated that, by manipulating the morphology and density of the Ni catalyst nanoparticles via changing the flow rate of the precursor gas mixture, the vertically aligned CNTs could be effectively controlled. The Raman results also indicated that the intensity ratio of the G and D bands (I_D/I_G) is decreased with increasing gas flow rate. TEM results suggest H₂ plasma pretreatment can effectively reduce the amorphous carbon and carbonaceous particles and, thus, is playing a crucial role in modifying the obtained CNTs structures.     

Temperature field distribution in multi-layered solid media heated with multi-modes laser beam

In the present paper we want to develop an analytical model to study the thermal behavior of multi-layered solid media in interaction with a laser beam. We suppose that each layer has a constant thermal conductivity. We consider that the laser beam is formed by decoupled [Phys Rev A 1996; 53: 4435] multi-modes Hermite–Gauss beams. The model is applied using the classical heat equation which was solved using the integral transform method [Infrared Phys Technol 2002; 42: 31; Optics Laser Technol 2004; 36: 219–22; Optics Laser Technol 2004; 36: 677–9; Proc SPIE 2003; 5227: 323].     

Thermal fields in laser–multi-layer structures interaction

In the present paper, we are dealing with the thermal fields for laser–periodic multilayer structures interaction. Our point of view is originally that we consider any order transverse laser beams, like heating sources. We consider that the laser beam acts in IR (Nd:YAG or CO₂ laser beam) and it is in one transverse mode or in only a few decoupled modes. In order to solve this problem, we will use the Green function method. Specific results are presented for a laser beam (Nd:YAG laser) operating in the mode TEM₀₁ and a two-layer structure.     

Effect of different electronic properties on 9-aryl-substituted BMVC derivatives for new fluorescence probes

We have previously illustrated that the electron donor of carbazole moiety and the electron acceptor of methyl pyridinium cation in 3,6-bis(1-methyl-4-vinylpyridinium) carbazole diiodide (BMVC) molecule could form an intramolecular charge-transfer state. The intramolecular twist of the vinyl group in bridging the donor and acceptor plays an important role in the BMVC fluorescence. Here, we have synthesized three 9-aryl-substituted BMVC derivatives with different electronic properties for the design of the second generation of fluorescence probes. The steady-state solvatochromic studies show no appreciable change to the charge transfer of BMVC by substituting an anisole electron-donating group at 9-position of BMVC. However, substituting a 9-nitrobenzyl electron-withdrawing group in BMVC could restrict the charge transfer in the excited state. Moreover, the increase of the fluorescence yields of 9-anisole BMVC and 9-phenyl BMVC upon interaction with DNA is even higher than that in glycerol, while the fluorescence yield of 9-nitrobenzyl BMVC upon interaction with DNA is much lower than that in glycerol. Although 9-nitrobenzyl BMVC is a good G-quadruplex stabilizer, substituting an electron-withdrawing group at 9-position of BMVC is not recommended for the design of fluorescence probes. On the other hand, co-localization between 9-phenyl BMVC and MitoTracker Red in the merged image of cells indicates that the 9-phenyl BMVC is a potential fluorescent mitochondrial probe.     

Homology of saddle point reduction and applications to resonant elliptic systems

In the setting of saddle point reduction, we prove that the critical groups of the original functional and the reduced functional are isomorphic. As application, we obtain two nontrivial solutions for elliptic gradient systems which may be resonant both at the origin and at infinity. The difficulty that the variational functional does not satisfy the Palais–Smale condition is overcame by taking advantage of saddle point reduction. Our abstract results on critical groups are crucial.     

On some nonlinear problems induced by an abstract maximal element principle

In this paper, by applying an abstract maximal element principle on quasi-ordered sets established by Lin and Du, we obtain a generalized Brézis–Browder principle, system (vectorial) versions of Ekeland's variational principle and maximal element principle and a vectorial version of Takahashi's nonconvex minimization theorem. Moreover, we investigate the equivalence between scalar versions and vectorial versions of these results.     

Elementary variational approach to zero-free solutions of a nonlinear eigenvalue problem

A variational approach is employed for obtaining zero-free solutions of a nonlinear eigenvalue problem that appears in several recent studies. Our proofs are elementary but our results are sharp and yield corrections to several existing assertions in the literature.