Observation of a Doppler broadening of the 4438 keV gamma-line of12C in processes12C(n,n′γ)12C and9Be(α, nγ)12C

A Doppler broadening is described of the 4438 keV spectral gamma-line observed by means of a Ge(Li) detector during the deexcitation of nuclei of¹²C in an inelastic scattering¹²C(n, n′γ)¹²C using an²⁴¹Am−Be source as well as during the reaction⁹Be(α, nγ)¹²C taking place in the Am−Be source. The FWHM of the spectral line is equal to (90±4) keV in the latter reaction and (64±8) keV in the former process. Experimental values agree well with theoretical ones. Presented at the Instrumental Activation Analysis Conference, IAA 79, June 4–8, 1979, Klučenice, Czechoslovakia.     

A needle-and-thread approach to bilayer transport: permeation of a molecular umbrella-oligonucleotide conjugate across a phospholipid membrane

A di-walled molecular umbrella, composed of two choloyl groups, one spermidine moiety, and a 5-thiol(2-nitrobenzoyl) "handle", was covalently attached to a 16-mer oligonucleotide (S-dT16) through a disulfide bond. Incubation of this conjugate (1) with vesicles made from 1-palmitoyl-2-oleyol-sn-glycero-3-phosphocholine and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (95/5, mol/mol) (200 nm diameter, extrusion) that contained entrapped glutathione (GSH) at 37 degrees C resulted in the liberation of the oligonucleotide and the umbrella-bound 5-mercapto(2-nitrobenzoyl) moiety (USH) via thiolate-disulfide interchange. The appearance of USH, together with the absence of leakage of entrapped GSH and a vesicular capture of the oligonucleotide that matches the extent of USH formation, provides compelling evidence for delivery of S-dT16 into the aqueous compartment of these vesicles. In a sense, the molecular umbrella functions like a "needle" in providing a pathway for the oligonucleotide (the "thread") to cross the membrane.     

A polymerized calix[6]arene monolayer having gas permeation selectivity that exceeds Knudsen diffusion

A polymerized monolayer of 5,11,17,23,29,35-hexamercaptomethyl-37,38,40,41,42-hexakis-(1-n hexadecyloxy)calix[6]arene (1) has been synthesized on the surface of an ca. 15 mum-thick film derived from poly[1-(trimethylsilyl)-1-propyne] (PTMSP). This monolayer exhibits a permeation selectivity toward He and SF6 that exceeds Knudsen diffusion. Analogous membranes made from a calix[6]arene that contains amidoxime headgroups (i.e., 2) showed Knudsen diffusion characteristics.     

Underquaternized anion exchange resins as covalent scavengers

The use of partially quaternized, chloromethylated polystyrene as a covalent scavenger of cholate ion in aqueous media has been demonstrated. The ability of such polymers to scavenge organic anions by covalent as well as by ionic means has important implications in the areas of medicinal and environmental chemistry, which are briefly discussed.     

Double N-N scattering on polarized proton target

The triple scattering depolarization transfer parameterD _t in elastic p-p scattering was measured at an energy of 660 MeV using a polarzied proton target. All measurements have been carried out with the help of an optical spark chamber.The following results have been obtained:D _t (90)=D(90)=0·54±0·10.D _t (130)=D(130)=0·72±0·11.Devoted to Professor V. Petrílka on his sixty-fifth birthday.On leave of absence from theInstitute for Computing Technique of the Czechoslovak Academy of Sciences, Prague.On leave of absence from theNuclear Research Institute of the Czechoslovak Academy of Sciences, e.On leave of absence from theFaculty of Nuclear Science and Physical Engineering of the Technical University, Prague.In conclusion the authors express their deep gratitude to S. M. Bilenky, G. Gozzika, M. Hansroul, L. Lapidus, M. Odehnal, M. Maly, B. S. Neganov, R. M. Ryndin and P. Winternitz for helpful discussions and J. Cechová, E. Dudová and H. Sternová for help in the work.     

Spin-2—on-line low temperature nuclear orientation facility at YASNAPP-2 complex in Jinr Dubna

The Spin-2 facility built at YASNAPP-2 experimental complex of the Joint Institute of Nuclear Research is described. The basic parameters of SPIN-2 and YASNAPP-2 are discussed.     

Total cross sections,elastic scattering observables and direct reconstruction of scattering matrix in np Interactions between 0.8 and 1.1 GeV at SATURNE II

Neutron-proton total cross section differences with the beam and target polarizations orientated either transversally or longitudinally with respect to the beam direction, as well as 11 spin dependent elastic scattering observables measured at SATURNE II as a function of energy and angle are presented. A major part of results was measured using the quasimonoenergetic polarized neutron beam and/or the polarized proton target. A small part of data was obtained using a polarized deuteron beam considered as a beam of quasifree neutrons and protons. The present paper represents a review of measured observables. Several sets of present data are compared with results obtained in other laboratories below 0.8 GeV. Imaginary parts of spin dependent forward amplitudes for np scattering and for the isospin stateI=0 were determined. First direct reconstruction of the np scattering matrix at 0.84 GeV is shown.We acknowledge support for this work from J. Arvieux, R. Beurtey, P. Borgeaud, P. A. Chamouard, A. Fleury, E. Heer, J. M. Laget, L. Musílek, L. Price, N. A. Russakovich, J. Saudinos, and J. Tolar. Discussions with J. Franz, J. M. Lagniel, C. Lechanoine-Leluc, G. Milleret, I. Strakovsky, and Y. Terrien have solved several problems. The exploitation of the polarized target owes a lot to G. Guillier, Ph. Marlet and J. Mommejat. We thank T. Lambert, E. Perrin, J. Poupard and J. P. Richeux for their efficient help in preparation of the experiment and the SATURNE II crew for unusual accelerator operations. Finally, we express our gratitude to Françoise Haroutel, who efficiently helped overcome all administrative requirements concerning a large international colaboration. This work was partly supported by the Swiss National Science Foundation and by the US Department of Energy Contract No. W-31-109-ENG-38.     

The gluing of a Langmuir-Blodgett bilayer

Poly(4-styrenesulfonate) has been used to ionically cross-link (glue together) a single Langmuir-Blodgett bilayer derived from an amphiphilic calix[6]arene bearing six hexadecyl and six methylene-trimethylammonium groups. The resulting film is of high quality and robustness, as judged by its He/N2 permeation selectivity and by its ability to withstand exposure to chloroform solvent. The creation of a stable organic membrane, having a thickness that is less than 6 nm and a He/N2 permeation selectivity of ca. 305, represents a milestone for LB technology.     

Fast non-destructive determination of iron and sulphur in coal by means of neutron radiative capture

The possibility of determination of iron and sulphur in large-scale samples of coal /20–50 kg/, based on process /n, /, was evaluated. The spectral lines of the doublet 7631 keV and 7645 keV were used for the determination of iron, while the line at 5421 keV was used for the determination of sulphur. The neutron source was²⁵²Cf /total neutron emission at 2.5×10⁷ s^–1/ located additionally in D₂O moderator. A Ge/Li/ detector was used for gamma radiation detection. The calibration dependencies of the analyzer were linear. In exposure times of up to 1 h, the detection limits of 0.34% and 0.64% and accuracies of 0.25% and 0.4% have been achieved in case of iron and sulphur, respectively.