A partial-wave analysis of the reaction π−p → K+K−n measured on a polarized target at ∼18 GeV/c

The reaction π^?p→K⁺K^?n has been studied on a hydrogen target (27 000 events) at 18.4 GeV/c and on a polarized target (54 000 events) at 17.2 GeV/c. A combination of results of both experiments allows a partial-wave analysis of the K⁺K^? system between 1.1 and 1.74 GeV mass without any model assumptions. In general our fits yield unique solutions. Using results of our previous analysis of π⁺π^? final states and assuming the dominance of the positive G-parity states in the K⁺K^? system, the branching ratios $\text{BR}\text{(}\text{K}\text{K}\text{/ππ)}$ of partial waves into $\text{K}\text{K}\text{and}\text{ππ}$ are determined. The S-wave appears to be mainly a broad ε (1300) with $\text{BR}\text{(}\text{K K}\text{/ππ) = 0.068}{}_{\mathrm{?0.021}}{}^{\mathrm{+0.017}}$. The weak P-wave can be described by a tail of the $\text{?(770)}\text{with BR}\text{(}\text{K K}\text{/ππ) = 0.081}{}_{\mathrm{?0.025}}{}^{\mathrm{+0.029}}$. The D-wave is interpreted in terms of a superposition of f(1270) + A₂(1310) + f′(1515) resonances. The fit yields $\text{BR}\text{(}\text{K K}\text{/ππ) = 0.069}{}_{\mathrm{?0.031}}{}^{\mathrm{+0.023}}$ for the f(1270) and BR(ππ/all) = 0.027_?0.013^+0.071 for the f′(1515). The F-wave shows the g(1690) meson with $\text{BR}\text{(}\text{K K}\text{/ππ) = 0.191}{}_{\mathrm{?0.037}}{}^{\mathrm{+0.040}}$. All the above values refer to the t bin between 0.01 and 0.20 (GeV/c)². Some results are also given for the high-t region.     

Use of 13C isotope shifts for assignment of deuterium labelling sites in 1,3-diphenylpropan-1-one

¹³C NMR spectroscopy was used for the unequivocal analysis of the mixture of products of RuCl₂[P(C₆H₅)₃]₃-catalysed transfer deuteriation of benzylideneacetophenone by (a) DCOONa/H₂O, (b) HCOONa/D₂O and (c) DCOONa/D₂O. Signal assignments in the ¹³C spectra were obtained mainly from the deuterium-induced ¹³C isotope shifts. The geminal ¹³C? ²H shift of the β-carbon of deuteriated 1,3-diphenylpropan-1-one is almost twice that for the α-carbon.     

Theory and physical importance of integrated state multipoles

We consider the polarisation properties of light emitted by heavy atoms after excitation by polarised electrons. It is discussed what information on spin-dependent forces can be obtained from the measurements.     

Light scattering from spherulitic materials

The azimuthal angular dependence of the depolarized component of the light scattered from spherulitic materials is derived by an algebraic method that avoids the difficult angular integrations of the usual approach. The result appears as a sum of products of two factors, a molecular factor, that depends only on the structure and the scattering angle θ, and a geometrical factor that depends only on the azimuthal angle ? and the scattering angle θ. The molecular factors are evaluated for models of spherulitic structure that assume a constant tilt of the optical polarizability tensor. The radial distribution, in principle, is arbitrary, and an evaluation for the layered spherulite is made. If the tilt angle is ω when the azimuthal patterns depend only on a linear combination of P₂(cos ω) and P₄(cos ω), where P_n(x) is the Legendre polynomial of order n. In our theory the V_H scattering pattern is a four-leaf clover whose axes are restricted by the theory to be at either 0 or 45° to the polarization directions.     

Selective hydrogen transfer from formic acid to α,β-unsaturated ketones by polystyrene-bound IrCl(CO)(PPh3)2

Polytyrene-anchored chlorocarbonylbis(triphenylphosphine)iridium has been shown to be a highly stable and active catalyst for the selective transfer hydrogenation of α,β-unsaturated ketones by formic acid.     

On the electron impact induced hydroxyl loss from o-nitrostyrene

Unimolecular hydroxyl (OD^˙) loss from regio- and stereo-specifically labelled o-nitrostyrenes 1a, 1c and 1d results in the formation of an ion which upon collisional activation gives identical mass spectra. Suggestions are made which aim at explaining: (i) the loss of stereochemical integrity of the diastereotopic methylene hydrogens in the course of hydroxyl elimination; and (ii) to account for the collision induced losses of CO and HNC from the [M—hydroxyl]⁺ ion.     

Zirconium-mediated SN2' substitution of allylic ethers: regio- and stereospecific formation of protected allylic amines

A new zirconium-mediated, regio- and stereospecific SN2' substitution of allylic ethers with a nitrogen nucleophile has been developed. Cbz-protected amine products were isolated in high yield from reactions with a wide range of Z allylic ethers. A mechanism of the allylic substitution consistent with the results of the kinetics and kinetic isotope effect studies was proposed.     

Latex bead immobilisation in PDMS matrix for the detection of p53 gene point mutation and anti-HIV-1 capsid protein antibodies

Two diagnostic chemiluminescent biochips were developed for either the detection of p53 gene point mutation or the serological detection of anti-HIV-1 p24 capsid protein. Both biochips were composed of 24 microarrays of latex beads spots (4×4) (150 m in diameter, 800 m spacing) entrapped in a poly(dimethylsiloxane) elastomer (PDMS). The latex beads, bearing oligonucleotide sequences or capsid protein, were spotted with a conventional piezoelectric spotter and subsequently transferred at the PDMS interface. The electron microscopy observation of the biochips showed how homogeneous and well distributed the spots could be. Point mutation detection on the codon 273 of the p53 gene was performed on the basis of the melting temperature difference between the perfect match sequence and the one base pair mismatch sequence. The hybridisation of a 20-mer oligonucleotide form the codon 273 including a one base pair mutation in its sequence on a biochip arrayed with non-muted and the muted complementary sequences, enabled a clear discrimination at 56°C between muted and wild sequences. Moreover, the quantitative measurement of the amount of muted sequence in a sample was possible in the range 0.4–4 pmol. Serological measurement of anti-HIV-1 p24 capsid protein on the biochip, prepared with 1-m-diameter latex beads, enabled the detection of monoclonal antibodies in the range 1.55–775 ng mL^–1. Such a range could be lowered to 0.775 ng mL^–1 when using 50-nm-diameter beads, which generated a higher specific surface. The validation of the biochip for the detection of anti-HIV-1 capsid protein antibodies was performed in human sera from seropositive and seronegative patients. The positivity of the sera was easily discriminated at serum dilutions below 1:1,000.     

Forward K1+ (892) production in K+p → π+Ks0p at 12.7 GeV/c

We have measured 618 K⁺p → π⁺K_S⁰p events at 12.7 GeV/c incident lab momentum, mass range 790 ? m_π⁺Ks⁰ ? 990 MeV and t range 0.01 ? ?t ? 0.60 (GeV/c)². The π⁺K_S⁰ mass spectrum is dominated by the K¹⁺ (892) resonance and a Breit-Wigner fit yields a mass m = 893.5 ± 1.1 MeV and a width Γ = 33.2 ± 4.1 MeV which is much narrower than measured hitherto. The t distribution of K¹⁺ (892) events shows a dip in the forward direction and an exponential fall off thereafter, consistent with dominance of helicity flip amplitudes. The spin density matrix is almost saturated by ρ₁₁ and ρ_1?1 which are very close to their maximum allowed value of $\text{1}\text{2}$ throughout the measured t range except in the very forward direction where ρ₀₀ and Re ρ₁₀ deviate from zero. Natural parity exchanges, therefore, dominate with unnatural parity exchanges being restricted to a small region in the forward direction. A Regge pole analysis of the differential cross sections of the present measurement in conjunction with previously measured total cross sections supports the f-coupled-pomeron hypothesis.