The double differential cross section of low momentum kaons (# 0.3 GeV͞c) from p 1 C collisions at subthreshold bombarding energies has been for the first time measured by the use of the CLAMSUD magnetic spectrometer installed at the CELSIUS storage ring. Invariant cross sections extracted from the data show a source rapidity shifted below the nucleon-nucleon rapidity, in agreement with the existence of multistep processes in the K 1 production cross section. The total cross section of the inclusive reaction 12 C͑p, K 1 ͒ at 1.2 GeV was extracted and compared with recent data systematics as a function of the proton bombarding energy. [S0031-9007 (98)06266-8] PACS numbers: 25.40.Ve, 25.40.QaWhile the production of pions at subthreshold energies, i.e., at energies lower than the threshold for free nucleonnucleon (NN) collisions, has been extensively studied both in proton-nucleus [1] and in nucleus-nucleus [2] collisions, only recently have the first data on the production of K 1 from proton-nucleus collisions in the subthreshold regime been published [3].

In this contribution the design and fabrication of bifunctional, photoresponsive hybrid metal nanoparticle assemblies is reported. Integration of tailored porphyrin and NO photodonor units into ca. 1 nm carboxy-terminated platinum induces the formation of particle nanoassemblies of ca. 10 nm, which are quite soluble in aqueous solution at physiological pH and exhibit a bichromophoric behavior. Direct monitoring of NO through an ultrasensitive NO electrode demonstrates that the nanoparticles are stable in the dark but supply NO at nanomolar level in a way exclusively regulated by light excitation. Besides, the typical red fluorescence arising from the porphyrin centers in the nanoassembly is not quenched extensively, offering a useful tool for mapping the localization of the nanoparticles in bio-environments. Overall these nanohybrids represent appealing bright point sources of NO to be tested in biological research in the perspective of practical application in the emerging field of nanomedicine.

We have synthesized herein a novel molecular conjugate integrating an anthracene chromophore and a viologen moiety in the same molecular skeleton, joined together by a p-xylene spacer. This conjugate preserves both the DNA intercalative properties of the anthracene polycycle and the reversible electrochemical behavior of the viologen unit. The simultaneous presence of these components in one single molecular structure increases the affinity towards DNA in solution with respect to that observed for the isolated functional units, probably due to a co-operation of intercalative and electrostatic binding modes. The molecular conjugate interacts with both single and double-stranded DNA absorbed on ITO surfaces. It is shown that the presence of the anthracene unit plays a key role in increasing the affinity for the electrode-bound DNA also for the reduced, monocationic form of the conjugate. The application of the synthesized compound as an electroactive indicator able to discriminate between non-hybridized and hybridized surface-immobilized DNA has been investigated. ExperimentalMaterials and methods 9-Anthracene methanol (98%), a,a 0 -dibromo para-xylene (97%), 4,4 0 -bypiridil (98%), potassium chloride, ammoniumChart 1 Molecular structure of the anthracene-viologen conjugate 1.

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