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The implementation of boron in several fields, such as in the creation of p-type semiconductors in electronics, has created the need for the accurate quantitative determination of its depth profile concentrations in near surface layers of various matrices. In the framework of IBA techniques, a combination of Elastic Backscattering Spectroscopy (EBS), along with Nuclear Reaction Analysis (NRA), has been proposed in order to address the current needs for boron depth profiling, based on the use of a proton beam. Deuterons offer superior mass resolution with respect to protons, having similar stopping power values, but, unfortunately, the lack of experimental datasets concerning the deuteron elastic scattering on boron impedes their use. Thus, in the present work, the first set of measurements for the 11B(d,d0) differential cross sections covering the Ed,lab=1300-1860 keV energy range for the backscattering angles of 150°, 160° and 170° was carried out. The study was conducted at the 5.5 MV Tandem Accelerator of the Institute of Nuclear and Particle Physics, in the National Center of Scientific Research “Demokritos”, Athens, Greece. The target was a thin, self-supporting aluminum foil, upon which a thin natB (isotopic ratio: 11B 80.1%, 10B 19.9%) layer was deposited using the sputtering technique at RBI, Zagreb, Croatia, followed by the evaporation of an ultra-thin layer of 197Au on top for wear protection and normalization purposes. The outgoing particles were detected using 6 Silicon Surface Barrier (S.S.B.) detectors and the differential cross sections for the elastic scattering were determined from the resulting spectra via the relative measurement technique.

Two families with the G syndrome of dysphagia, ocular hypertelorism and male genital anomalies are described. One family had a lethal case with a laryngotracheo-oesophageal cleft, while the other showed only a relatively mild expression of the syndrome in both sexes. This wide variability and the new findings are discussed, and the importance of an early diagnosis for the successful management of severe cases is emphasized.

The effects of I- ions on O2 evolution by photosystem 2 particles, which were depleted of the 18-kDa and the 23-kDa extrinsic proteins of the O2 evolution complex by NaCl washing (dPS2 particles) were examined. In the absence of Cl- (incompetent dPS2) I- stimulated O2 evolution up to 3-6 mM, depending on the associated cation, and inhibited it at higher concentrations. In the presence of Cl- (competent dPS2), I- was inhibitory at all concentrations. The inhibition was reversible, it occurred at a site preceding Tyrz (Tyr residue mediating electron transfer from H2O to photosystem 2), and it interfered noncompetitively with the reactivation of incompetent dPS2 with Cl-. Furthermore, the organic salts tetrabutyl ammonium iodide and tetraphenyl phosphonium iodide proved to be stronger inhibitors than the inorganic NaI. This is interpreted as an indication of a negatively charged surface, situated behind a hydrophobic permeability barrier. Permeant organic cations, being better compensators of the inner surface charge than Na+, are also more apt in facilitating access of the I- ions to the inhibitory site in the vicinity of Tyrz.

A study has been made (i) of the effect of the suspension medium composition on the kinetics of permeabilization of Anacystis nidulans to ions by lysozyme, and (ii) of the consequences of permeabilization on the photosynthetic apparatus of the cyanobacterium. Ion-permeable, osmotically resistant cells (permeaplasts) were prepared by a 15 min lysozyme treatment in 0.05 M sodium 4-(2-hydroxyethyl)-1-piperazineethanesulfonate. Permeabilization causes detachment of phycobilisomes from the thylakoid surface and partial dissociation of phycobiliprotein multimers. The permeaplasts contain, however, virtually intact thylakoids, as testified by their fully functional photosynthetic electron-transport chain and their capacity for photosynthetic control. Supplementation of the lysozyme incubation medium with osmotica delays cell permeabilization, while prolongation of the lysozyme treatment inactivates the photosynthetic electron transport at a site preceding electron donation by 1,5-diphenylcarbazide.

Lymphocyte cultures from homozygotes for the beta-thalassaemia gene were found to contain chromosomal gaps, breaks, and rearrangements more often than those from controls. Culture time seemed to have a determinant effect on the results. The possible influence of folic acid deficiency is discussed.

The tendency of isolated intact phycobilisomes to disperse into multimeric phycobiliprotein subunits in dilute phosphate buffer is diminished, or even eliminated, by means of covalent polypeptide cross-linking with glutaraldehyde, or dimethyl suberimidate. Employing sensitized fluorescence spectrophotometry in order to detect transitions of the type phycobilisome → phycobiliprotein multimers, and second-derivative absorption spectrophotometry to detect transitions of the type phycobiliprotein multimers → monomers, we investigated the molecular basis of phycobilisome stabilization by these two cross-linkers. A network of intrahexamer and interhexamer covalent cross-links prevents the dissociation of glutaraldehyde-treated phycobilisomes into monomers, even under the strong chaotropic effect of KNO 3 and KSCN solutions, but fails to protect against polypeptide unfolding in concentrated urea solution. Dimethyl suberimidate, on the other hand, introduces only intramonomer cross-links, and thus it does not prevent dissociation to monomers in the presence of KNO 3 and KSCN. Increased hydrophobicity of phycobiliprotein subunits, as a result of the alkylation of −NH 2 by the diimido ester, or the dialdehyde, is an additional structure-stabilizing factor.

A case of partial trisomy 6p is reported with a review of the various characteristics of this syndrome.

Ann Genet

A case of oligohydramnios syndrome was found to have an XYY karyotype and an inherited 9qh inversion. It is suggested that normal and extra Y chromosomes are a predisposing factor in the aetiology of severe congenital renal anomalies.

The propositus' grandmother has a fragile 16q and belongs to a large family where several abortions and congenital anomalies were recorded. The portion distal to the fragile site was inherited as an extra fragment by the proposius' father who has it in 11% of his lymphocyte metaphases. This phenotypically harmless fragment has a high affinity for satellited chromosomes and was probably a main factor in the causation of the rearrangement that produced the partial trisomy 20p found in the propositus.

Fryns and his colleagues described two children with a remarkably similar phenotype, and suggested their condition was due to a partial or total deletion of the long arm of chromosome 16 distal to band q21. We report the same phenotype in a boy whose blood karyotype was normal.

ENDOCRINE ASSESSMENT OF MULTI-TRANSFUSED PATIENTS WITH HOMOZYGOUS β-THALASSEMIA 16-24 YEARS OLD

Proton elastic scattering and inelastic scattering to the first excited state of 6He have been measured over a wide angular range using a 40.9A MeV 6He beam. The data have been analyzed with a fully microscopic model of proton-nucleus scattering using 6He wave functions generated from large space shell model calculations. The inelastic scattering data show a remarkable sensitivity to the halo structure of 6He., Comment: 9 pages, 3 figures. RevTeX. Replaced figure 3 with updated figure

The excitation functions for (7)Li + (28)Si quasielastic scattering at 150 degrees and 170 degrees have been measured at sub- and near-barrier energies (0.6 to 1.3 VB) and the corresponding barrier distributions derived. The results were analyzed within the framework of the optical model using a procedure similar to one used on previous results for (6)Li + (28)Si employing double-folded potentials calculated using the BDM3Y1 effective interaction. The variation of the surface strength of the optical potential as a function of incident energy was compared for the two systems (6)Li + (28)Si and (7)Li + (28)Si, the barrier distributions being used to help better define the potential at the lowest energies. The barrier distributions were also analyzed with continuum-discretized coupled-channel (CDCC) and coupled reaction channel (CRC) calculations as a means of investigating the influence of breakup and transfer reactions on these quantities for these light, weakly bound projectiles. Physical Review C