Withanolides from Withania adpressa

From the leaves of Withania adpressa, a plant endemic to Sahara of Morocco and Algeria, the novel steroidal lactone (22R)‐14α,15α,17β,20β‐tetrahydroxy‐1‐oxowitha‐2,5,24‐trien‐26,22‐olide (= (15S,17S)‐14,15,17,20‐tetrahydroxy‐22,26‐epoxyergosta‐2,5,24‐triene‐1,26‐dione; 1 ), was isolated, along with three known compounds, withanolides F ( 2 ), J ( 3 ), and oleanolic acid. Their structures were mainly solved by in‐depth 1D‐ and 2D‐NMR (including ADEQUATE) experiments, as well as by HR‐MS analyses and chemical evidence.     

Crystal structure of monomethylammonium tribromocadmate(II)

CH₃NH₃CdBr₃ crystallizes in the space group Ccm2₁, a = 13.693(1) Å, b = 7.906(1) Å, c = 6.886(1) Å, V = 745.46(15) ų, Z = 4, D _x = 3.42 Mg m^–3. The structure of the title compound is one-dimensional consisting of infinite chains made of face sharing CdBr₆ octahedra. The methylammonium groups are situated in the space between chains. The cations and anions are joined by hydrogen bonding.     

Extension d'un théorème de Harte et applications aux algèbres de Jordan-Banach

In this paper we study some questions related to spectral theory in Jordan-Banach algebras. Firstly, we introduce the notion of exponential spectrum and then we extend to Jordan-Banach algebras a theorem due to Robin Harte in the associative case. Secondly, these results are used to get a theorem on spectral perturbation by inessential elements in Jordan-Banach algebras.

     

Existence and decay rates for a coupled Balakrishnan-Taylor viscoelastic system with dynamic boundary conditions

In this paper, we are concerned with a coupled viscoelastic wave system with Balakrishnan-Taylor dampings, dynamic boundary conditions, source terms, and past histories. Under suitable assumptions on relaxation functions and source terms, we prove the global existence of solutions by potential well theory and we establish a more general decay result of energy, in which the exponential decay and polynomial decay are only special cases, by introducing suitable energy and perturbed Lyapunov functionals.     

Space charge packets in polyethylene nano-scales under dc applied voltages

In this paper, we are interested in space charge packet phenomenon generated at submicron scales in insulating polyethylene materials that have not been extensively investigated in all previous theoretical modeling and experimental works. Indeed, a bipolar charge transport model is proposed to simulate space charge dynamics in nano-scale polyethylene material under dc high electric field. For these scales, our results show space charge packet appearance which induces new dynamics that are marked on injected and conduction current oscillations. In addition, our results also show the establishment of post breakdown phenomena that are indicated by an external current abrupt increase without saturation.     

Crystal structure of pentakis ethylenediammonium bis undecachlorodiantimonate(III) tetrahydrate, (NH3(CH2)2NH3)5(Sb2Cl11)2·4H2O

The pentakis ethylenediammonium bis undecachlorodiantimonate(III) tetrahydrate salt is monoclinic with the following unit cell dimensions:a=16.271(5) Å,b=13.004(4) Å,c=13.932(4) Å, β=111.72(2)°, space groupP2₁/c withZ=2. The structure was solved by Patterson methods and refined to a finalR value of 0.023 for 4435 reflections withF ₀>4σ(F ₀). The structure shows a layer arrangement perpendicular to thea axis: planes of the [Sb₂Cl₁₁]⁵⁻ bioctahedra alternate with planes of [NH₃(CH₂)₂NH₃]²⁺ dications. The [Sb₂Cl₁₁]⁵⁻ bioctahedra are connected through O−H...Cl hydrogen bonds, such that infinite chains of composition [Sb₂Cl₁₁(H₂O]_n ⁵ⁿ⁻ are formed in the structure, parallel to the twofold axis. These chains are themselves interconnected by means of N−H...Cl and O−H...Cl bonds originating from the [NH₃(CH₂)₂NH₃]²⁺ entities and the water molecules, respectively, and form a threedimensional network.     

Utility of 2‐[4‐(3‐oxobenzo[f]‐2H‐chromen‐2‐yl)‐1,3‐thiazol‐2‐yl]ethanenitrile in heterocyclic synthesis

Pyrazolo[4,3‐d]pyrimidines, pyrazolo[4,3‐d]triazolino[4,3‐a]pyrimidines, 3‐(2‐thiazolyl)thiophenes, thiazolo[3,2‐a]pyridine and pyrazolo[1,5‐a]pyrimidines were synthesized from 2‐[4‐(3‐oxobenzo[f]‐2H‐chromen‐2‐yl)‐1,3‐thiazol‐2‐yl]ethanenitrile. The newly synthesized compounds were elucidated by elemental analysis, spectral data, chemical transformation and alternative synthesis route whenever possible.