Encapsulation of Tetraazaannulenato Compounds in Matrix by Sol-Gel Process

The hybrid organic-inorganic catalyst constituted by {5,7,12,14-tetramethyldibenzo[b,i]-1,4,8,11-tetraaza[14]annulenato} nickel (II), NiTMTAA, encapsulated in an alumina matrix has been prepared. NiTMTAA was synthesized by the reaction of nickel acetate with o-phenylenediamine in the presence of 2,4-pentanedione under argon atmosphere. The alumina hybrid material was obtained by a non hydrolytic sol-gel route, through the condensation of aluminum chloride with diisopropylether in the presence of NiTMTAA. The material has been prepared through precipitation from a gel. Characterization of the alumina hybrid material has been performed by ultra violet-visible spectroscopy, electron spectroscopic imaging, surface area, atomic absorption, infrared spectroscopy, and thermogravimetric analysis. The ultra violet-visible absorption spectrum of the hybrid material has bands characteristic of the NiTMTAA compound showing that the structure of NiTMTAA has been preserved in the hybrid material. The new material has a surface area of 300 m²/g. The electron image was that of a non-crystalline microstructure. Comparison between the leaching of NiTMTAA from NiTMTAA adsorbed on commercial neutral alumina confirm that in the non-hydrolytic materials the NiTMTAA is entrapped and not only adsorbed on the alumina surface. The use of conventional hydrolytic sol-gel process leads to the complete leaching of NiTMTAA from matrix, underlining the importance of the non-hydrolytic alumina gel process in the matrix preparation. The new catalysts prepared were tested for their ability to catalyze the epoxidation of (Z)-cyclooctene using iodosylbenzene as oxygen donor, giving moderate yields in the epoxidation (40%), while the homogeneous NiTMTAA is inactive due to NiTMTAA bleaching. These results emphasize the effect of the non-hydrolytic alumina matrix to prevent chemical degradation of NiTMTAA.     

High transverse momentumη production in π− p, π+ p,andpp interactions at 280 GeV/c

The inclusive cross sections for η production by the interactions of 280 GeV/c momentum π^?, π⁺, and proton beams in hydrogen have been measured. The kinematical range covered is ?0.45<x _F <0.45, and 4.0<P _T <7.0 GeV/c for Feynmanx _F and transverse momentum respectively. The η to π⁰ cross section ratios are given for the three reactions. The ratio of π^? p to π⁺ p cross sections for η production in the above kinematic ranges is 1.22±0.08±0.11.     

Synthesis and crystal structure of 5-methyl-5,10-dihydrophenarsazine

The X-ray crystal structure of 5-methyl-5,10-dihydrophenarsazine, C₁₃H₁₂NAs, has been determined. The crystals are orthorhombic, space group P2₁2₁2₁, a = 8.511(4), b = 5.690(1), c = 23.535(9) Å, V = 1139.7(1.0)A³, and Z = 4. Least-squares refinement converged to R = 0.049 and Rw = 0.045. The central ring is in a boat conformation and the 5-methyl group is in the axial position with respect to the central ring. The folding angle between the planes of the two benzo rings is 154.1(4)°.     

Event-by-event search for charged-neutral fluctuations in Pb-Pb collisions at 158 A⋅GeV

We analyse the proton electromagnetic form factor ratioR(Q ² ) =QF ₂ (Q ² )/F ₁ (Q ² ) as a function of momentum transferQ ² within perturbative QCD. We find that the prediction for (R(Q ² ) at large momentum transferQ depends on the exclusive quark wave functions, which are unknown. For a wide range of wave functions we find thatQF ₂ F ₁ ～ const. at large momentum transfer, which is in agreement with recent JLAB data.     

Production of π0 mesons and charged hadrons in\bar v neon and ν neon charged current interactions

The average multiplicities of charged hadrons and of π⁺, π^? and π⁰ mesons, produced in \(\bar v\) Ne and νNe charged current interactions in the forward and backward hemispheres of theW ^±-nucleon center of mass system, are studied with data from BEBC. The dependence of the multiplicities on the hadronic mass (W) and on the laboratory rapidity (y _Lab) and the energy fraction (z) of the pion is also investigated. Special care is taken to determine the π⁰ multiplicity accurately. The ratio of average π multiplicities \(\frac{{2\left\langle {n_{\pi ^O } } \right\rangle }}{{[\left\langle {n_{\pi ^ + } } \right\rangle + \left\langle {n_{\pi ^ - } } \right\rangle ]}}\) is consistent with 1. In the backward hemisphere \(\left\langle {n_{\pi ^O } } \right\rangle \) is positively correlated with the charged multiplicity. This correlation, as well as differences in multiplicities between \(\mathop v\limits^{( - )} \) and \(\mathop v\limits^{( - )} \) , \(\mathop v\limits^{( - )} \) scattering, is attributed to reinteractions inside the neon nucleus of the hadrons produced in the initial \(\mathop v\limits^{( - )} \) interaction.     

Gene Expression on DNA Biochips Patterned with Strand‐Displacement Lithography

Lithographic patterning of DNA molecules enables spatial organization of cell‐free genetic circuits under well‐controlled experimental conditions. Here, we present a biocompatible, DNA‐based resist termed “Bephore”, which is based on commercially available components and can be patterned by both photo‐ and electron‐beam lithography. The patterning mechanism is based on cleavage of a chemically modified DNA hairpin by ultraviolet light or electrons, and a subsequent strand‐displacement reaction. All steps are performed in aqueous solution and do not require chemical development of the resist, which makes the lithographic process robust and biocompatible. Bephore is well suited for multistep lithographic processes, enabling the immobilization of different types of DNA molecules with micrometer precision. As an application, we demonstrate compartmentalized, on‐chip gene expression from three sequentially immobilized DNA templates, leading to three spatially resolved protein‐expression gradients.     

A study of the centrally producedK *0 K^{*0} \bar K^{*0} final state in the reactionpp→p f (K + K -π+π-)p s at 300 GeV/c

The reactionpp→p _f (K ⁺ K ^-π⁺π^-)p _s , where theK ⁺ K ^? π⁺π^- system is centrally produced, has been studied at 300 GeV/c. TheK ^*0 \(K^{*0} \bar K^{*0} \) final state has been observed and the cross sections for its central production are found to be the same at 300 and 85 GeV/c. TheK ^*0 \(K^{*0} \bar K^{*0} \) final state appears to be produced as a non-resonant threshold enhancement.