Production of helium fragments in197Au-emulsion collisions at 10.6 A GeV

We present a systematic analysis on the helium projectile fragments produced from 10.6 A GeV¹⁹⁷Auemulsion interactions in an experiment conducted at the Brookhaven AGS. Total charge changing and partial production cross-sections are measured experimentally on the basis of helium multiplicity. The multiplicity distribution of helium fragments which are produced collectively obey a KNO scaling. The transverse momentum distribution of these particles indicates that they are produced from two different independent sources.We are thankful to the BNL technical staff and specially to Dr. D. Beavis for his help in the exposure of emulsion stacks. Thanks are due to Profs. Y. Takahashi and G. Romano for their help in the preparation and development of the emulsion stacks. We appreciate the discussions with Prof. H. Stocker and J. Aichelin. This work was supported by D.O.E. under Grant No. DE-FGO2-90ER 40566.     

Simple formula for nuclear charge radius

A new formula for the nuclear charge radius is proposed, dependent on the mass numberA and neutron excessN-Z in the nucleus. It is simple and it reproduces all the experimentally available mean square radii and their isotopic shifts of even-even nuclei much better than other frequently used relations.This work is partly supported by the Polish Committee of Scientific Research under contract No. 203119101     

Photorefractive properties of ruthenium-doped potassium niobate

Photoconductivities and photovoltaic currents of ruthenium-doped KNbO₃ are orders of magnitude larger than that of undoped and ion-doped crystals. KNbO₃:Ru is very sensitive for holographic recording with red light and the photovoltaic current increases sublinearly with light intensity.     

Moment closure hierarchies for kinetic theories

This paper presents a systematicnonperturbative derivation of a hierarchy of closed systems of moment equations corresponding to any classical kinetic theory. The first member of the hierarchy is the Euler system, which is based on Maxwellian velocity distributions, while the second member is based on nonisotropic Gaussian velocity distributions. The closure proceeds in two steps. The first ensures that every member of the hierarchy is hyperbolic, has an entropy, and formally recovers the Euler limit. The second involves modifying the collisional terms so that members of the hierarchy beyound the second also recover the correct Navier-Stokes behavior. This is achieved through the introduction of a generalization of the BGK collision operator. The simplest such system in three spatial dimensions is a 14-moment closure, which also recovers the behavior of the Grad 13-moment system when the velocity distributions lie near local Maxwellians. The closure procedure can be applied to a general class of kinetic theories.     

Miniature electrophoresis for speed and productivity

Attempts to miniaturize electrophoresis (EP) to save time or enhance productivity and efficiency remains a challenge for science and industry. Other advantages of miniaturization include: increased sensitivity, saving of reagents, greater yield of data, and enabling studies where only small samples are available. Since electrophoresis that takes hours may be reduced to a matter of minutes, the limitations of miniaturization in clinical, industrial, and research applications are evaluated. Clinical electrophoresis (EP) on cellulose acetate media can be performed in 3.5 min instead of 20–45 min and on SDS polyacrylamide gels in 15–30 min compared with conventional 3–8 h.     

Electronic spectra of compounds containing the conjugated tetratomic system X(V)Y=Z

The correlation of the spectra of conjugated tetratomic and triatomic systems was examined by means of corrected Dewar rules.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1353–1356, June, 1992.     

Cellulose hydrolysis using zinc chloride as a solvent and catalyst

Cellulose gel with < 10% of crystallinity was prepared by treatment of microcrystalline cellulose, Avicel, with zinc chloride solution at a ratio of zinc chloride to cellulose from 1.5 to 18 (w/w). The presence of zinc ions in the cellulose gels enhanced the rate of hydrolysis and glucose yield. The evidence obtained from X-ray diffraction, iodine absorption experiments; and Nuclear Magnetic Resonance spectra analysis suggested the presence of zinc-cellulose complex after Avicel was treated with zinc chloride. Zinc-cellulose complex was more susceptible to hydrolysis than amorphous cellulose. Under the experimental condition, cellulose gels with zinc ions were hyrolyzed to glucose with 95% theoretical yield and a concentration of 14% (w/v) by cellulases within 20 h. The same gel was hydrolyzed by acid to glucose with 91.5% yield and a concentration of 13.4% (w/v).     

Carbonyldinitrosyltris(fluorosulfato)tungstate(II) and ‐Molybdate(II) Anions: Synthesis,Spectroscopy, and Density Functional Theory Calculations

Carbonyldinitrosyltris(fluorosulfato)tungstate(II) and ‐molybdate‐(II) anions, [fac‐M(CO)(NO)₂(SO₃F)₃]^? (M=W, Mo), which are novel weakly coordinating anions that contain a metal carbonyl/nitrosyl moiety, have been generated in fluorosulfonic acid and completely characterized by multinuclear NMR, IR, and Raman spectroscopy as well as ESI mass spectrometry. ESI MS measurements performed for the first time on a superacidic solution system unambiguously reveal the formation of the monoanionic, mononuclear W and Mo complexes formulated as [M(CO)(NO)₂(SO₃F)₃]^? (M=W, Mo). Multinuclear NMR spectroscopic studies at natural abundance and ¹³C and ¹⁵N enrichment clearly indicate the presence of one CO ligand, two equivalent NO ligands, and two types of nonequivalent SO₃F^? groups in a 2:1 ratio. The IR and Raman spectra reveal that the two equivalent NO ligands have a cis conformation, thus indicating a fac structure. Density functional calculations at the B3LYP level of theory predict that these anions have a singlet ground state (¹A′) with a C_s symmetry along with C–O and N–O vibrational frequencies that are in agreement with the experimental observations. Mulliken population analysis shows that the monovalent negative charge is dispersed on the bulky sphere, the surface of which is covered by all the negatively charged O and F atoms with charge densities much lower than SO₃F^?, suggesting that [fac‐M(CO)(NO)₂(SO₃F)₃]^? (M=W, Mo) are weakly nucleophilic and poorly coordinating anions.     

Sequential injection spectrophotometric determination of phenylephrine hydrochloride in pharmaceutical preparations

A fully automated sequential injection spectrophotometric method for the determination of phenylephrine hydrochloride in pharmaceutical preparations is reported. The method is based on the condensation reaction of the analyte with 4-aminoantipyrine in the presence of potassium ferricyanide. The absorbance of the condensation product was monitored at 503 nm. A linear relationship between the relative peak height and concentration was obtained in the range 0.5-17.5 mg l⁻¹. The detection limit (as 3σ value) was 0.09 mg l⁻¹ and repeatability was 0.8 and 0.6% at 2.5 and 5 mg l⁻¹, respectively. Results obtained by this method agreed very well with those obtained by the AOAC official method.