In the title compound, C(11)H(9)NO(4), the carboxyl group bonded to the six-membered ring lies close to the plane of the 1H-indole ring system [dihedral angle = 13.13 (9)°], whereas the carb-oxy-lic acid group linked to the five-membered ring by a methyl-ene bridge is close to perpendicular [78.85 (9)°]. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules, generating (110) sheets.

A synthesis of C17α-OH-tigogenin, the aglycon of aspafiliosides E and F, is described. The main features of the synthesis are three cascade processes, which involve the iodo-lactonization of furostan-26-acid to open ring E, a cascade hydrolysis/intramolecular SN2 process to close ring E, and a cascade intramolecular redox-ketalization process to close ring F. This synthesis would enrich the str...

Abstract An optical vortex possesses a ring-shaped spatial profile and orbital angular momentum (OAM) owing to its helical wavefront. This form of structured light has garnered significant attention in recent years, it enabled new investigations fundamental physics applications. One such exciting application is laser-based material transfer for nano-/micro-fabrication. In this work, we demonstr...

This paper presents a polarization insensitive frequency selective surface (FSS) based on concentric ring slots with five closely spaced passbands. The proposed FSS unit cell contains coupled supplementary innermost slot. close band response within the first transmission bands is achieved by influence of modified geometry obtained inclusion sixth added slot causes appearance stopband, due to co...

a series of ortho -hydroxypyridine-4-ones were prepared in high yields and evaluated for antioxidant and iron chelating activities. n 1 -h hydroxypyridinones va , vb , and ve were the best radical scavengers in dpph free radical scavenging assay. compound vb was proved to be the most potent compound in hydrogen peroxide scavenging assay. all of the synthesized compounds had very close chelating...

It is known that if a 2-universal hash function H is applied to elements of a block source (X1, . . . , XT ), where each item Xi has enough min-entropy conditioned on the previous items, then the output distribution (H,H(X1), . . . , H(XT )) will be “close” to the uniform distribution. We provide improved bounds on how much min-entropy per item is required for this to hold, both when we ask tha...

In this paper, we introduce the notion of $G_\infty$-ring spectra. These are globally equivariant homotopy types with a structured multiplication, giving rise to power operations on their and cohomology groups. We illustrate structure by analysing when Moore spectrum can be endowed structure. Such $G_\infty$-structures correspond underlying ring, indexed Burnside ring. exhibit close relation be...

In the title mol-ecule, C(24)H(20)N(2)O(4), the five-membered oxadiazole ring is nearly planar (r.m.s. deviation = 0.053 Å) and the phenyl ring of the biphenyl unit attached to it forms a dihedral angle of 73.2 (1)°; the other phenyl ring is close to coplanar with the oxadiazole ring [dihedral angle = 6.2 (2)°].