Explicit secular equations of Stoneley waves in a non-homogeneous orthotropic elastic medium under the influence of gravity

The problem of Stoneley waves in a non-homogeneous orthotropic elastic medium under the influence of gravity was studied recently by Abd-Alla and Ahmed [A.M. Abd-Alla, S.M. Ahmed, Stoneley waves and Rayleigh waves in a non-homogeneous orthotropic elastic medium under the influence of gravity, Appl. Math. Comput. 135 (2003) 187–200], who derived the secular equation of the wave in the implicit form. In this paper, by using an appropriate representation of the solution, we obtain the secular equation of the wave in the explicit form. Moreover, considering its special cases, we derive explicit secular equations for a number of investigations of Stoneley waves under the influence of gravity, for which only the implicit dispersion equations were previously obtained.     

Some Weighted Energy Classes of Plurisubharmonic Functions

In this paper we study relations between the weighted energy class E_cmathcal{E}_{chi} introduced by S. Benelkourchi, V. Guedj and A. Zeriahi recently with Cegrell’s classes Emathcal{E} and Nmathcal{N}. Next we establish a generalized comparison principle for the operator M _χ . As an application, we prove a version of existence of solutions of Monge–Ampère type equations in the class E_c(H,W)mathcal{E}_{chi}(H,Omega).     

On exponential stability of nonlinear differential systems with time-varying delay

General nonlinear differential systems with time-varying delays are considered. Several explicit criteria for exponential stability are presented. An example is given to illustrate the obtained results. To the best of our knowledge, the results of this note are new.     

Regularity dimension of sequences and its application to phylogenetic tree reconstruction

The concept of dimension is a central development of chaos theory for studying nonlinear dynamical systems. Different types of dimensions have been derived to interpret different geometrical or physical observations. Approximate entropy and its modified methods have been introduced for studying regularity and complexity of time-series data in physiology and biology. Here, the concept of power laws and entropy measure are adopted to develop the regularity dimension of sequences to model a mathematical relationship between the frequency with which information about signal regularity changes in various scales. The proposed regularity dimension is applied to reconstruct phylogenetic trees using mitochondrial DNA (mtDNA) sequences for the family Hominidae, which can be validated according to the hypothesized evolutionary relationships between organisms.     

Lattices generated by Chip Firing Game models: Criteria and recognition algorithms

It is well-known that the class of lattices generated by Chip Firing Games (CFGs) is strictly included in the class of upper locally distributive lattices (ULD). However a necessary and sufficient criterion for this class is still an open question. In this paper we settle this problem by giving such a criterion. This criterion provides a polynomial-time algorithm for constructing a CFG which generates a given lattice if such a CFG exists. Going further we solve the same problem on two other classes of lattices which are generated by CFGs on the classes of undirected graphs and directed acyclic graphs.     

Synthesis of NiO Crystals Exposing Stable High‐Index Facets

Metal oxides exposing high‐index facets are potentially impactful in catalysis and adsorption processes owing to under‐coordinated ions and polarities that alter their interfacial properties compared to low‐index facets. Here, we report molten‐salt syntheses of NiO particles exposing a variety of crystal facets. We show that for a given anion (nitrate or chloride), the alkali cation has a notable impact on the formation of crystals exposing {311}, {611}, {100}, and {111} faces. Based on a parametric analysis of synthesis conditions, we postulate that the crystallization mechanism is governed by the formation of growth units consisting of Ni^II complexes whose coordination numbers are determined by temperature and the selection of anion (associated to the coordination sphere) and alkali cation (associated with the outer coordination sphere). Notably, our findings reveal that high‐index facets are particularly favored in chloride media and are stable under prolonged periods of catalysis and steaming.     

A fractional map with hidden attractors: chaos and control

The European Physical Journal Special Topics - This paper studies the dynamics of a new fractional-order map with no fixed points. Through phase plots, bifurcation diagrams, largest Lyapunov...     

Low-cost and versatile analytical tool with purpose-made capillary electrophoresis coupled to contactless conductivity detection: Application to antibiotics quality control in Vietnam

In this study, the development of our purpose-made capacitively coupled contactless conductivity detection (C⁴D) for CE is reported. These systems have been employed as a simple, versatile, and cost-effective analytical tool. CE-C⁴D devices, whose principle is based on the control of the ion movements under an electrical field, can be constructed even with a modest financial budget and limited infrastructure. A featured application was developed for quality control of antimicrobial drugs using CE-C⁴D, with most recent work on determination of aminoglycoside and glycopeptide antibiotics being communicated. For aminoglycosides, the development of CE-C⁴D methods was adapted to two categories. The first one includes drugs (liquid or powder form) for intravenous injection, containing either amikacin, streptomycin, kanamycin A, or kanamycin B. The second one covers drugs for eye drops (liquid or ointment form), containing either neomycin, tobramycin, or polymyxin. The CE-C⁴D method development was also made for determination of some popular glycopeptide antibiotics in Vietnam, including vancomycin and teicoplanin. The best detection limit achieved using the developed CE-C⁴D methods was 0.5 mg/L. Good agreement between results from CE-C⁴D and the confirmation method (HPLC- Photometric Diode Array ) was achieved, with their result deviations less than 8% and 13% for aminoglycoside and glycopeptide antibiotics, respectively.     

The cyclohexadienylidenemethanone radical cation is a more stable distonic isomer of ionized benzaldehyde

Quantum chemical calculations (G3B3 and B3LYP/6-311++G(d,p)) and tandem mass spectrometric experiments demonstrate the higher stability of 1,3-cyclohexadienylidenemethanone radical cation compared to ionized benzaldehyde. Characterized by a heat of formation of 833 kJ mol⁻¹ (at 298 K), this ketene C₇H₆O⁺ isomer is found 43 kJ mol⁻¹ more stable. It has been generated by ion/molecule reaction between ionized benzaldehyde and neutral methanol, a new example of proton transport catalysis tautomerization. The greater stability of the ketene ion is due to the low IE of the neutral (7.49 eV).