Thorium adsorption by oxidized biochar fibres derived from Luffa cylindrica sponges

Journal of Radioanalytical and Nuclear Chemistry - The present study deals with the preparation of oxidized biochar fibres derived from Luffa cylindrica sponges and the subsequent adsorption of...     

Acylaminoacetyl derivatives of active methylene compounds. 4

Meldrum's acid has been found to be effectively acylated using the imidazolides of N-protected glycines, X-NHCH₂COOH (X = -COPh, -COMe, -Z, -Boc, -COOMe and -COOEt). The corresponding C-acylation compounds were isolated in high yields and were readily converted to the N-protected tetramic acids. It was shown by pmr spectroscopy that these acids exist as the enol tautomers in DMSO-d₆ solution, whereas in deuteriochloroform solution both the enol and keto tautomers can be observed.     

Global existence of generalized solutions of the spherically symmetric Einstein-scalar equations in the large

In this paper we study the global initial value problem for the spherically symmetric Einstein-scalar field equations in the large. We introduce the concept of a generalized solution of our problem, and, taking as initial hypersurface a future light cone with vertex at the center of symmetry, we prove, without any restriction on the size of the initial data, the global, in retarded time, existence of generalized solutions.Research supported in part by National Science Foundation grants MCS-8201599 to the Courant Institute and PHY-8318350 to Syracuse University     

A convenient synthesis of 3-aryl-4H- Benzopyrano[3,4-d]isoxazol-4-ones

Regioselective 1,3-dipolar cycloaddition of nitrile oxides 5a-c to ethyl o-hydroxycinnamate (3) gave the corresponding ethyl trans-3-aryl-4,5-dihydro-5-(2-hydroxyphenyl)-4-isoxazolecarboxylates 6a-c . Their structure was confirmed by reductive cleavage to 1 and compounds 9a-c . Compounds 6a-c afforded upon heating in the presence of pyridine the 3-aryl-4H-[1]benzopyrano[3,4-d]isoxazol-4-ones 11a-c . Compound 10c was also isolated from 6c and transformed thermally into 11c .     

Gravitational field with toroidal topology

The Weyl formalism for static, axially symmetric solutions to Einstein's equations is employed to examine solutions of Einstein's equations with toroidal topology. We investigate a particular family of solutions that contain the Schwarzschild, Curzon, Bach-Weyl, and metric (also known as the Zipoy-Voorhees metric) as special cases.     

Discrete Talbot effect in waveguide arrays

We report the first observation of discrete Talbot revivals in one-dimensional waveguide arrays. Unlike continuous systems where the Talbot self-imaging effect always occurs irrespective of the pattern period, in discrete configurations this process is only possible for a specific set of periodicities. Recurrence of different input periodic patterns is observed in good agreement with theory.     

Soliton dragging by dynamic optical lattices

We report on the phenomenon of controllable soliton dragging by dynamic optical lattices induced by three imbalanced interfering plane waves. Because of such an imbalance, the transverse momentum of the lattice does not vanish, and thus the dynamic lattice can cause soliton dragging. The dragging rate is shown to depend on the amplitude and on the angle of incidence of the third plane wave making the optical lattice.     

Discrete surface solitons

It is theoretically shown that discrete nonlinear surface waves are possible in waveguide lattices. These self-trapped states are located at the edge of the array and can exist only above a certain power threshold. The excitation characteristics and stability properties of these surface waves are systematically investigated.     

Nondiffracting beams in periodic media

We identify nondiffracting beams in two-dimensional periodic systems, exhibiting symmetry properties and phase structure characteristic of the band(s) they are associated with.