Withanolides from Aureliana fasciculata var. fasciculata

In the first phytochemical study of the Aureliana genus (Solanaceae), two new withanolides, 1 and 2 , together with two known sterols, were isolated from the MeOH extract of the leaves of Aureliana fasciculata var. fasciculata. The structures were established as (4S,22R)‐16α‐acetoxy‐5β,6β‐epoxy‐4β,17α‐dihydroxy‐1‐oxowitha‐2,24‐dienolide (aurelianolide A) and (4S,22R)‐16α‐acetoxy‐4β,17α‐dihydroxy‐1‐oxowitha‐2,5,24‐trienolide (aurelianolide B). The new compounds possessed the unusual 16α,17α‐dioxygenated group and were fully characterized by spectroscopic techniques, including ¹H‐ and ¹³C‐NMR (DEPT), as well as 2D‐NMR (HMBC, HMQC, ¹H,¹H‐COSY, NOESY) experiments, and HR‐MS.     

A simple technique for constructing exact solutions to nonlinear differential equations with conformable fractional derivative

The modified simple equation method is an interesting technique to find new and more general exact solutions to the fractional differential equations in nonlinear sciences. In this paper, the method is applied to construct exact solutions of (2+1)-dimensional conformable time-fractional Zoomeron equation and the conformable space-time fractional EW equation.     

Thermal Conductivity of Polymer Composite Material Based on Phenol-Formaldehyde Resin and Boron Nitride

Russian Physics Journal - The paper presents the results of studies of thermal conductivity, structure, and physico-chemical properties of samples of polymer composite material based on...     

Low-energy supersymmetry and the Tevatron bottom-quark cross section

A long-standing discrepancy between the bottom-quark production cross section and predictions of perturbative quantum chromodynamics is addressed. We show that pair production of light gluinos, of mass 12 to 16 GeV, with two-body decays into bottom quarks and light bottom squarks, yields a bottom-quark production rate in agreement with hadron collider data. We examine constraints on this scenario from low-energy data and make predictions that may be tested at the next run of the Fermilab Tevatron collider.     

Peculiarities of grid control over the current in a discharge with a cathode spot on the cesium liquid-metal cathode

We report on the results of successful implementation of full grid control in a cesium discharge with a cathode spot. The discharge is quenched by a negative grid pulse for a discharge current density up to 75 A/cm² in the grid plane for voltage switching up to 100 V in the pressure range 0.5–1.5 Pa for a voltage drop of 5–6 V in the discharge. It is shown that quenching is the break-off type. The discovered effect of “evacuation” of the heavy component (ions) from the grid-anode gap to the cathode region leads to an unusually long (hundreds of microseconds) time of stabilization of the steady state in the discharge under the experimental conditions.     

μ+SR frequency shifts in the van‐Vleck paramagnet PrIn3

As part of an ongoing μ⁺SR study on cubic van‐Vleck paramagnets of the PrM₃ series ( M\ =\ In,Pb,Tl,Sn), in which the CEF level scheme varies systematically, we present preliminary static μ⁺SR results on a single crystal of PrIn₃. From the angular dependence and from the appearance of the μSR spectra, we could determine that stopped μ⁺ occupy octahedral sites of the (1/2, 0, 0) type, i.e. sites with 2 Pr and 4 In atoms as neighbors. The spectral frequency shifts can be accounted for by assigning to the Pr sites essentially unperturbed 4f dipole moment values, as derived from bulk magnetization measurements. The temperature dependence of the shifts scales to a good accuracy with the bulk susceptibility. It is concluded that unlike previous observations with PrNi₅, the local perturbations induced by an interstitial μ⁺ on the CEF levels of neighboring Pr in the PrIn₃ system are small compared with the unperturbed level splitting itself. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparison of stabilization modes of a symmetrical third-order non-linear oscillatory unit

The possibility of constructing symmetrical stabilized oscillator models that operate in several phases instead of operating in two phases, as is more usual, is considered in the present paper. In particular, symmetrical oscillator models operating in three phases are discussed comprehensively. An interesting feature of their dynamic behaviour, e.g. the appearance of limit cycles which are regionally stable and not orbitally stable, as is the case in the two phase counterpart, is suggested and dealt with.