Radiotracer analysis of the physico-chemical state of trace elements in aqueous solutions

The suitability of zone electrophoresis and of free-liquid electrophoresis for investigation of the physico-chemical forms of trace elements in aqueous solutions has been examined. Comparison of the electrophoretic mobilities of tervalent cerium determined by these two methods has demonstrated that adsorption of trace elements on the supporting medium renders zone electrophoresis unsuitable for investigation of hydrolytic and other reversible reactions of trace elements accompanied or preceded by significant adsorption. Free-liquid electrophoresis should be preferably used for this purpose as it is much less complicated by adsorption effects.     

Field induced magnetic density in the Pauli paramagnet YNi5

The induced magnetic density of the enhanced Pauli paramagnet YNi₅ has been measured by polarized neutron diffraction at 100 K and in an applied field of 48 kOe. The magnetic density is localized on Ni sites where a 3d form factor, similar to that of Ni metal, is observed. The induced Ni moment is different for the two crystallographic sites: (2.4 ± 0.6) × 10^-3 μ_B on Ni_I on the 2c site and (4.1 ± 0.8) × 10^-3 μ_B on Ni_II on the 3g site. This difference must be associated with the difference of the Y surroundings of each site. The results are discussed from the band structure of the alloy.     

On the self-affinity of heparan sulfates from quiescent or proliferating normal 3T3 cells and from SV40-transformed cells

35S-Labelled heparan sulfates derived from the culture medium (extracellular), a trypsinate of the cells (pericellular) and the cell residue (intracellular) of quiescent normal, proliferating normal or SV40-transformed 3T3 cells were analyzed for charge heterogeneity, by ion exchange chromatography and for self-affinity, by chromatography on heparan sulfate-agarose gels. Quiescent normal cells retained most of their heparan sulphate intra- or pericellularly. The surface-exposed material was charge heterogeneous and had a strong affinity for heparan sulfate. In cultures of growing cells and transformed cells most of the heparan sulfate was found in the medium. The heparan sulfate retained on the surface or growing cells had a lower self-affinity than did the corresponding material from normal and transformed cells. Although cell surface heparan sulfates from transformed cells showed affinity for a matrix substituted with the total heparan sulfate pool, the affinity for one particular subtype was much less pronounced or non-existent.     

Improved separation of the rare sulfur isotopes by infrared multiphoton dissociation of SF6

The dissociation probabilities of³²SF₆ and some of³⁴SF₆ have been measured at a large number of CO₂ laser lines both at room temperature and at 140 K. The longwavelength wing of this dissociation spectrum is exponential in the wavenumber. Its logarithmic slope is proportional to the inverse temperature. Selectivities are high enough at 140 K, that the photons are consumed only for the rare isotope in the case of³⁴SF₆ and nearly so for³⁶SF₆. For³³SF₆ further improvement of the selectivity would be desirable.     

Activation of CH bonds by octaethylporphyrinrhodium dimer

Octaethylporphyrinrhodium dimer, [RhOEP]₂, reacts thermally with arylmethyl CH bonds to produce octaethylporphyrinbenzylrhodium compounds.     

Gas chromatographic separation of sugars by on-column injection on glass capillary columns

Sugars were separated gas chromatographically on short apolar glass capillary columns by using cold, on-column injection (OCI) techniques. After silylation, oligomers up to the hexasaccharides could be efficiently separated in resonable retention times. Response factors of silylated sugars were determined as a function of varying sample amounts and concentrations. The optimum injection amount was found to be 1 μl in heptane as solvent.     

Girsanov functionals and optimal bang-bang laws for final value stochastic control

Girsanov's theorem is a generalization of the Cameron-Martin formula for the derivative of a measure induced by a translation in Wiener space. It states that for ? a nonanticipative Brownian functional with ∫|?|² ds < ∞ a.s. and $\text{d}\text{P}\text{?}\text{=exp[ζ(?)] d}\text{P}$ with $\text{E}\text{?}\text{{1}=1}$, where $\text{ζ(?) = ∫?}\text{d}\text{w-}\text{1}\text{2}\text{∫|?|}{}^2\text{d}\text{s}$, the translated functions $\text{(Tw)(t) = w}{}_{\mathrm{t}}\text{-}\text{∫}\text{0}\text{t}\text{?}\text{d}\text{s}$ are a Wiener process under P?. The Girsanov functionals exp [ζ(?)] have been used in stochastic control theory to define measures corresponding to solutions of stochastic DEs with only measurable control laws entering the right-hand sides. The present aim is to show that these same concepts have direct practical application to final value problems with bounded control. This is done here by an example, the noisy integrator: Make E{x²₁}∣small, subject to dx_t = u_t dt + dw_t, |u|? 1, x_t observed. For each control law there is a definite cost v(1?t, x) of starting at x, t and using that law till t = 1, expressible as an integral with respect to (a suitable) P?. By restricting attention to a dense set of smooth laws, using Itô's lemma, Kac's theorem, and the maximum principle for parabolic equations, it is possible to calculate sgn v_x for a critical class of control laws, then to compare control laws, “solve” the Bellman-Hamilton-Jacobi equation, and thus justify selection of the obvious bang-bang law as optimal.     

Metals in organic syntheses : IX. The isolation and molecular structure of trans-[PtCl(COC6H13-n)(PPh3)2], an intermediate precursor in the catalytic hydroformylation of 1-hexene

The complex trans-[PtCl(COC₆H₁₃-n)(PPh₃)₂] (I) has been synthesized by treating cis-[PtCl₂(PPh₃)₂] and 1-hexene with carbon monoxide under pressure in EtOH at 100°C. When in combination with SnCl₂-2H₂O, complex I is an intermediate precursor in the highly regioselective catalytic hydroformylation of 1-hexene, which readily occurs in a solvent such as a ketone.The crystal and molecular structure of complex I has been determined from three dimensional X-ray diffractometer data. The complex crystallizes in the triclinic space group P$\text{1}$. Cell parameters are as follows: a 15.869(8), b 12.306(8), c 11.437(7) Å, α 109.8(1), β 76.6(1), γ 112.9(1)°, Z  2. Fullmatrix least-squares refinement converged at R  0.058 (R_w  0.064). The structure has approximately square planar geometry, and shows no unusual dimensions.     

Distinguishing Between Electrons and γ-Rays in Experiment TGV Using a Pulse Rise Time

The TGV (Telescope Germanium Vertical) collaboration is interested in the measurement of double-beta decay of ⁴⁸Ca (TGV I) and ¹⁰⁶Cd (TGV II). The background in the experiment TGV I has been suppressed by several methods. One of them was based on distinguishing between electrons and -rays due to the different rise time of the signals obtained from semiconductor detector. Two experimental setups have been tested, the first one used a charge-sensitive analog-to-digital converter, while the second one utilized digital oscilloscope. The reduction of the background counting rate (due to -rays) in single HPGe detector by a factor of (1.4-3.8) was reached.