The electromagnetic and hadronic diffractive dissociation of O ions

Events which satisfy the kinematics of p(¹⁶O,CHep), with low excitation energy in the (CHe) system and a low-energy recoil proton, have been identified in the interactions of 200 GeV/nucleon ¹⁶O ions with nuclear emulsion. An eikonal DWIA estimate of the target A-dependence of strong-interaction diffractive dissociation suggests that, on the basis of these hydrogen data, most of the (CHe) final states, previously ascribed to electromagnetic dissociation on heavy nuclei, might rather be hadronic in character. This contamination is very much less important in the dominant (NH) channel.     

Investigation of the decay of charmed particles produced in neutrino interactions

The decay of charmed particles produced by high-energy neutrinos has been studied by an experiment using simultaneously emulsion, bubble chamber and counter techniques. Eight charmed particle candidates, 5 positively charged and 3 neutral, have been found in the emulsion, where their production and decay have been directly observed. One of these events is identified as a Λ_c⁺ baryon of mass 2.26±0.02 GeV/c² which undergoes the decay Λ_c⁺→pK^?π⁺ after a proper time of (7.3±0.1) · 10^?13 s.A statistical analysis of the other observed decays leads to the mean-life values τ⁺=(2.5_?1.1^+2.2) · 10^?13 s, τ⁰=(0.53_?0.25^+0.57) · 10^?13 s, for the sample of charged particles enriched by a similar event found in a previous experiment, and for the sample of 3 neutral particles, respectively. The former value is only slightly affected by including in the sample the Λ_c⁺ event or excluding that of the previous experiment.     

Membrane-mediated interactions of rod-like inclusions

Inclusions embedded in lipid membranes undergo a mediated force, due to the tendency of the membrane to relax its excess of elastic energy. In this paper we determine the exact shape of a two-dimensional vesicle hosting two different inclusions, and we analyse how the inclusion conformation influences the mediated interaction. We find non-trivial equilibrium configurations for the inclusions along the hosting membrane, and we derive the complete phase diagram of the mediated interaction. In particular, we find a non-vanishing mediated force even when the distance between the inclusions is much greater than their size. Our model can be applied to describe the mediated interactions of parallel, elongated inclusions embedded in three-dimensional membranes. Received 22 October 2001 and Received in final form 8 March 2002     

The chemical state of arsenic in minerals of environmental interest--an XPS and an XAES study

A systematic analytical study using X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) has been carried out to characterize the chemical state of arsenic in complex environmental samples. The conventional approach, which relies on the chemical shift of the core levels As3d, provides ambiguous results in determining the chemical environment of arsenic. A more accurate approach, based on the Auger parameter and on the Wagner (Chemical State) plot, which combines AsLMM kinetic energy and As3d binding energy, was adopted. This novel method for determining the chemical state of arsenic was employed to completely characterize arsenic in complex environmental samples.     

Stereospecific epoxidation of anthracyclinones: a route to 8(r)-methoxydaunomycinone

Stereoselective epoxidation of $\text{1}$, the 7,8-unsaturated derivative of daunomycinone, followed by $\text{trans}$ opening of the epoxide $\text{2}$, afforded 8(R)-methoxydaunomycinone $\text{6a}$; its configuration at C-8 was determined by chemical correlation and PMR studies.     

Development of a new assay for the screening of hypochlorous acid scavengers based on reversed-phase high-performance liquid chromatography

A new assay for the screening of hypochlorite/hypochlorous acid (XOCl) scavengers, based on the reversed-phase high performance liquid chromatographic analysis of human serum albumin (HSA, 0.2% in 100 mM sodium phosphate, pH 7), before and after oxidation by XOCl (1.6 mM), was developed. XOCl induced a significant decrease of the area under the chromatographic peak of HSA at 280 nm due to the oxidation of the aromatic amino acids tryptophan and tyrosine, as suggested by the literature and by the chromatographic analyses and the electrochemical study performed here. The assay was validated by testing known XOCl scavengers such as ascorbic acid, cysteine, glutathione, S-methylglutathione and alpha-lipoic acid and other antioxidants such as carnosine and chlorogenic acid, which inhibited the oxidation of HSA. Quantitative activities were calculated using an original formula based on the changes of the area of the albumin peak. Electrochemical data collected here in a homogeneous medium showed that the anodic potentials of the antioxidants tested are less positive (ascorbic acid, chlorogenic acid and cysteine) or similar (alpha-lipoic acid) compared with those of the aromatic residues (tryptophan and tyrosine) of HSA oxidized by XOCl. However, as expected, carnosine, glutathione and S-methylglutathione were inactive at a glassy-carbon, gold or platinum electrode.     

Fragmentation in neutrino and antineutrino charged current interactions on proton and neutron

Some experimental properties of the charged hadronic fragments are compared for νp, νn, \(\bar vp\) and \(\bar vn\) interactions: multiplicities of forward and backward going particles,x _F distributions for pions, fragmentation functions and theirQ ² andW ² dependence. The results are compared with the predictions of the Lund fragmentation model.