A quantum hydrodynamic model for multicomponent quantum magnetoplasma with Jeans term

The effect of Jeans term in a multicomponent self-gravitating quantum magnetoplasma is investigated employing the quantum hydrodynamic (QHD) model. The effects of quantum Bohm potential and statistical terms as well as the ambient magnetic field are also investigated on both dust and ion dynamics driven waves in this Letter. We state the conditions that can drive the system unstable in the presence of Jeans term. The limiting cases are also presented. The present work may have relevance in the dense astrophysical environments where the self-gravitating effects are expected to play a pivotal role.     

Nonplanar Ion Acoustic Solitary Waves in a Two-Electron Temperature Plasma

Linear and non-linear properties of ion acoustic wave （IAW） propagating in a two-electron temperature plasma are investigated from both analytical and numerical perspectives by employing the fluid theory. A one-dimensional modified Korteweg de Vries equation is derived for the IAW using the reductive perturbative technique in a nonplanar geometry. It is observed that the ion acoustic soliton in a two-temperature plasma admits rarefactive （dip like） solitons. In the limit that the cold electron population goes to zero, it is observed that the ion acoustic soliton yields compressive （hump like） solitons. The variation of the ion acoustic soliton with different plasma parameters is also shown. The present investigation may be beneficial to explain some aspects of ion acoustic rarefactive solitary structures observed in space environments where two-electron temperature plasmas have been observed.     

Synthesis and Crystal Structures of <Emphasis Type="Italic">o</Emphasis>-[(Phenyl/<Emphasis Type="Italic">p</Emphasis>-methoxyphenyl)carbamoyl]benzene Sulfonamides

Abstract  

o-[(Phenyl/p-methoxyphenyl)carbamoyl]benzene sulfonamides were synthesized in a straightforward manner utilizing directly saccharin and aniline/p-anisidine as starting material and their crystal structures have been determined. (C₁₃H₁₂N₂O₃S): Mr = 276.31, monoclinic, P2₁/c, a = 10.277(6), b = 7.501(2), c = 16.261(10) ?, β = 96.37(2)°, V = 1,245.8(11) ?³, Z = 4. (C₁₄ H₁₄ N₂ O₄ S): Mr = 306.33, monoclinic, P2₁/c, a = 10.381(5), b = 7.861(2), c = 16.837(9) ?, β = 93.43(2)°, V = 1,371.5(10) ?³, Z = 4. In both structures the phenyl rings are inclined at 47.09(7) and 39.88(5)° with respect to each other and the structures are characterized by extensive inter and intramolecular hydrogen bonds.     

3‐Germyl‐3,3‐di­methyl­propionic acid derivatives

The crystal structures of 3,3‐di­methyl‐3‐(tri­chloro­germyl)­propionic acid, [Ge(C₅H₉O₂)Cl₃], 3,3‐di­methyl‐3‐(tri­phenyl­germyl)­propionic acid, [Ge(C₆H₅)₃(C₅H₉O₂)], and 3,3‐di­methyl‐3‐(tri‐p‐toly­lgermyl)­propionic acid, [Ge(C₇H₇)₃(C₅H₉O₂)], have slightly distorted tetrahedral geometries about the Ge atoms. All the structures form dimers via strong O—H·O hydrogen bonds, resulting in eight‐membered rings that can be best described in terms of graph‐set notation (8).     

Formation of a chiral NPPN ligand via metallation of acyclic NPNCN systems

A new type of bidentate N,N'-chelating ligand containing a chiral phosphorus centre has been synthesized via the metallation of an acyclic NPNCN species. The zwitterionic ligand backbone contains a phosphenium centre stabilised by an imido phosphine fragment.     

The structure of a new crystalline cevane alkaloid: its identity with persicanidine B and harepermine

The structure of a new crystalline base (melting point (mp) 167-169 degrees C) obtained from Fritillaria imperialis was elucidated as (20R, 25R)-5alpha,17beta-cevanine-3beta,6beta-diol, X-ray diffraction analysis of the mono-hydrate. The base was found to be identical with persicanidine B and also with harepermine.     

A cytotoxic triketone-phloroglucinol-bullatenone hybrid from Lophomyrtus bullata

Cytotoxic activity against the P388 cell line was seen in a crude extract of the New Zealand shrub Lophomyrtus bullata(Myrtaceae). Bioactivity-guided isolation led to a compound with NMR spectra complicated by the presence of two isomers. These crystallised together and an X-ray structure showed them to be stereoisomeric hybrids of triketone, phloroglucinol and bullatenone units. NMR measurements on the mixed isomers, as well as a cyclic ether produced from them by acid catalysed dehydration, were consistent with these structures. The natural products, named bullataketals A and B, have cytotoxic activity against the P388 cell line (IC(50) 1 microg ml(-1)), and antimicrobial activity against Bacillus subtilis.     

Intra- and intermolecular second-sphere coordination chemistry: formation of capsules,half-capsules,and extended structures with hexaaquo- and hexaamminemetal ions

In the design of novel extended solids, particularly those based on weaker interactions, reliable "synthons" are a valuable commodity. This work concerns the hydrogen-bonded assemblies which result from the second-sphere coordination interactions between a highly preorganized trisulfonate ligand and hexaaquo metal ions. Significantly, supramolecular structural variation, which may be rationalized on the basis of the features of the molecular building blocks, is observed. The results are formation of second-sphere capsules with trivalent ions (Fe(3+), Cr(3+), Al(3+)), and half-capsules with divalent ions (Mg(2+), Zn(2+)). The divalent systems further assemble into extensively hydrogen-bonded hexagonal nets. Effects of geometrical variation of the building blocks are also observed when a Jahn-Teller-distorted divalent ion (Cu(2+)) is substituted for the perfectly octahedral species. The second-sphere effects on the stabilization of the primary coordination sphere are illustrated by TGA experiments. In these assemblies, the potential of a new supramolecular synthon is illustrated, that being the complementary cis-aquo sulfonate interaction. These complexes illustrate the general utility of second-sphere effects, both as an assembly tool and to stabilize metal complexes in the solid state. Finally, as a comparison, a hydrogen-bonded assembly with a hexaammine complex of a trivalent metal (Co(3+)) is presented, which forms an extended network with a completely altered hydrogen bonding array.     

Heteroatom influence on the pi-facial selectivity of Diels-Alder cycloadditions to 1-oxa-4-thia-6-vinylspiro[4.5]dec-6-ene, 3-methoxy-3-methyl-2-vinylcyclohexene, and 3-methoxy-2-vinylcyclohexene

The facial selectivities of the Diels-Alder cycloadditions of several dienophiles to the title substrates were studied. The observed selectivities are interpreted as a consequence of the relative steric interactions offered by the substituents. The addition of dimethylacetylene dicarboxylate (DMAD) is influenced by the electrostatic repulsion arising from the interaction of an electron pair orbital on the acetal oxygen and the orthogonal pi-orbital of the acetylene unit in DMAD in the syn-to-oxygen addition of the latter. This repulsion is offset on coordination of Li+ to the said oxygen electron pair orbital, and the addition thus proceeds syn to oxygen. The enhanced and accelerated syn-to-oxygen addition in lithium perchlorate in nitromethane is interpreted as a consequence of the coordination of Li+ to both the acetal oxygen and a heteroatom in the dienophile that brings them in close proximity to facilitate a reaction. The Li+-oxygen combination, however, also exerts some steric effect that results in reduced syn-to-oxygen addition of dienophiles having large substituents such as N-phenylmaleimide.     

Quantum magnetic collapse

We study the thermodynamics of degenerate electron and charged vector boson gases in very intense magnetic fields. In degenerate conditions of the electron gas, the pressure transverse to the magnetic field B may vanish, leading to a transverse collapse. For W bosons an instability arises because the magnetization diverges at the critical field B(c) = M(2)(W)/e. If the magnetic field is self-consistently maintained, the maximum value it can take is of the order of 2B(c)/3, but in any case the system becomes unstable and collapses.