On the use of a dead-time meter for pile-up corrections

Correction for pile-up losses in the amplifier is possible by the dead-time fraction indicator of the ADC in case of long-lived radionuclides. If the dead-time meter has been calibrated, an accuracy of 1.5% is feasible up to a dead-time fraction of 25%. The precision decreases from 1.5% at 10% dead-time fraction to 3% at a deadtime fraction of 30%.     

Influence of Cyclodextrins on the Kinetics of Oxidation of Amino Acids and BSA by Hydrazyl Radicals

The kinetics of oxidation of amino acids (Arg, His, Lys, Phe, Thr and Tyr), a dipeptide (Gly-His), and BSA (bovine serum albumin) by two persistent water soluble free radicals of the hydrazyl type has been studied.The rate decreases in the order Arg>Lys>Tyr>Thr>HisBSAPheGly-His with bothfree radicals. Addition to the reaction mixture of - and -cyclodextrin decreases the oxidation rate, probably due to amino acidencapsulation in the cyclodextrin cavity. -Cyclodextrin protects more efficiently against oxidation than -cyclodextrin.     

Strategies to vectorize conventional SCF-Cl algorithms

Recent high-performance computers, especially supercomputers, achieve very high-speed operations but bring about serious I/O problems in quantum chemical computations. Strategies to vectorize conventional SCF-CI algorithms are discussed relating to the I/O problems. The conventional SCF-CI algorithm which is proposed here reduces I/O processing by eliminating all sorting routines and redundant integral files and generates directly nonzero and nonredundant PK integrals with a vectorizable canonically-ordered list. The new implementation has been undertaken and successfully realized as a program system named GSCF3. The vector to scalar acceleration rate of GSCF3 on the HITAC S-810 are as follows: 2.5 5 in the AO integral evaluation, 5 12 in the SCF calculation, 15 30 in the four-index integral transformation, 10 20 in the CI matrix diagonalization, and overall 510 through SCF-CI.     

Kinetik der Bindung von Dansylsarkosin (DS) zur Spezifizierung von Humanalbumin (HSA) in Serumkonserven

Zusammenfassung In Spenderserum und handelsüblichen Serumkonserven wurde die Bindung von Dansylsarkosin (DS) an Humanalbumin (HSA) mit Hilfe von stopped-flow-Messungen bestimmt. Die Umlagerung vom instabilen in den stabilen DS-HSA Komplex erfolgt mit einer Halbwertzeit von 3 ms. Die Halbwertzeit der Dissoziation beträgt für alle untersuchten Seren 25 ms. Wegen unterschiedlicher Affinitäten des Anlagerungskomplexes erfolgt die Bindung von DS nach Sterilisation mit -Propiolacton (BPL) und UV-Licht langsamer als ohne Behandlung der Seren.

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Specification of human albumin (HSA) in preserved serum by dansylsarcosine (DS) binding kinetics

Summary Complexation of dansylsarcosine (DS) with human serum albumin (HSA) has been determined by stopped-flow in fresh human serum and commercial available serum. Conversion of the low affinity into the high affinity DS-HSA complex occurs with a half-life of 3 ms. Dissociation half-life was for all investigated seras 25 ms. Due to different affinity constants of the low affinity complex, binding reaction is slower for serum sterilized by -propiolacton and UV-light in comparison with untreated serum.

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Die Arbeit wurde durch die DFG unterstützt     

Donorstärken in 1,2-Dichloräthan

Zusammenfassung Kalorimetrische und spektrophotometrische Untersuchungen über die Donorstärke einer Anzahl nicht-wäßriger Lösungsmittel zeigen, daß die relative Reihung der Donorstärken unabhängig von der Natur des Akzeptors ist. Die Donorreihung lautet gegenüber SbCl₅, Jod und Phenol folgendermaßen: Pyridin > Dimethylsulfoxid > Dimethylacetamid Dimethylformamid > > Trimethylphosphat Diphenylphosphoroxychlorid > Diäthyläther > Aceton > Propandiol-1,2-carbonat > Acetonitril > > Selenoxychlorid Phosphoroxychlorid Benzoylchlorid > > Thionylchlorid > Sulfurylchlorid.

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Calorimetric and spectrophotometric work on the donor strength of various non-aqueous solvents have shown that the relative order of donor strength is independent from the nature of the acceptor. The order of donor strength towards SbCl₅, I₂ and phenole is pyridine > dimethylsulfoxide > dimethylacetamide dimethylformamide > trimethylphosphate diphenylphosphonic chloride > diethyl ether > acetone > propane diol-1,2-carbonate > acetonitrile > selenium oxychloride phosphorus oxychloride benzoyl chloride > thionyl chloride > sulfuryl chloride.

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Mit 1 Abbildung     

Insertion of 3d- and 4f-Elements into Silver Iodide

The interaction of manganese and some 4f-metals (M) with silver iodide is studied. The samples are obtained by sputtering M onto the surface of polycrystalline AgI films (0.2 m, 300 K) in a vacuum. Optical absorption in the samples is interpreted as the insertion of M ions into AgI with the formation of dopants AgI:M. A new phase with an optical bandgap of 3.7 eV emerges in the samples with elevated concentrations of La, Ce, Pr, Nd, Sm, or Dy (n _M/n _Ag 0.1). X-ray diffraction patterns for such samples with Sm correspond to structures with large interfacial distances, for example, 0.99, 0.87, 0.76, and 0.67 nm. In air, AgI forms in the samples with a new phase; this process is hindered by the sputtered protective coatings. According to optical absorption data, X-ray diffraction, and local microanalysis the Mn insertion into AgI is followed by the formation of a new phase (2Ag:Mn:4I), which may belong with solid electrolytes Ag₂MI₄, where nonmagnetic M are known (Zn, Cd, Sn, Hg, Pb).     

Study of free volume parameters of polystyrenes of different molecular architecture by positron annihilation lifetime measurement

Differences of size, content and size distribution of free volumes in linear branched and three-armed polystyrenes, synthesized by radical and anionic processes, were observed by positron annihilation lifetime measurements. The temperature dependence of an average free volume radius was quite similar among polystyrenes of different architectures and molecular weight distributions. The free volume radius increased with temperature, from 0.27 nm (T:60 K) to 0.29 nm (T:260 K) and 0.30 nm (T _g:363 K), then to 0.35 nm (423 K), showing turning at and transition temperature. The free volume content decreased from 60 K to 220 K to 300 K showing peculiar minimum at 220 K to 300 K depending on the molecular shape, increased above 320 K, upto 340 to 360 K. The free volume contents decreased with an increase of molecular weight and by an addition of oligomer or plasticiser, suggesting differences in relaxation time or molecular motion between the edge and middle portions of molecular chain and filling effect of smaller molecules in free volumes, respectively. The apparent free volume fraction showed clear variations atT andT _g. Size distribution of free volumes suggested more complicated behavior of free volume upon the molecular relaxations and filling effect.     

Experimental investigation on tritium gettering with hydrogen uranyl phosphate (HUP)

At room-temperature and atmospheric pressure, using electrode disks of various sizes, under the action 4 7Vdc eletric field, we gettered tritium gas from 2.2L of air containing (0.15 18.61)×10⁸ Bq of tritium and (3000 12000) ppm of moisture during 50 hours or so the efficiency of gettering tritium was over 95%. Applying liquid scintillation counting method, we measured the tritium in the disks after gettering, and found that the amounts of tritium in the disks were equal to those reduced in the tested tritiated air.     

Oxidation of Formic and Oxalic Acids in an Electrodeless Electrochemical Reaction

Decomposition of formic and oxalic acid and of sodium formate and sodium oxalate (0.1 M solutions) in an electrodeless electrochemical reaction was studied. The oxidation kinetics was analyzed in terms of the previously developed model. The decomposition yields of formic acid and sodium formate are 0.5 and 1 molecule/(100 eV), respectively, which is comparable with the radiation-chemical decomposition yield, taking into account the installation efficiency.     

Electron-impact-induced anisotropic etching of silicon by hydrogen

The etch rate of silicon in a hydrogen low-pressure discharge plasma can be strongly enhanced by electron bombardment, reaching presently up to 1000 Å/min. The etch rate increases linearly with increasing electron current density and hydrogen pressure (range 0.05–0.7 mbar) and decreases with increasing temperature, yielding an activation energy of –4.2 kcal/mole in a temperature range of 80 to 300°C. The etching remains anisotropic within the whole pressure range studied.     

The composition of volatile and particulate hydrocarbons in urban air

Summary The hydrocarbon composition of the particle and gas phases in the urban atmosphere has been studied by filtration and parallel adsorption on active charcoal and polyurethane foam (PUF). Gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS) have been used for the analysis of the organic matter extracts obtained with each system. In the case of the particle and PUF samples these extracts were fractionated into aliphatic and aromatic compounds. This approach has allowed to identify up to 247 hydrocarbon molecules showing that C0–C5 alkylbenzenes are the major compounds in the charcoal extracts whereas C14–C23 n-alkanes, C0–C4 alkylnaphthalenes, C0–C4 alkylbiphenyls and C3–C5 alkylbenzenes are those predominantly found in the PUF materials. The particles essentially contain C17–C38 n-alkanes and parent polycyclic aromatic hydrocarbons (PAH). These qualitative differences are paralleled by a progressive concentration decrease from the more to the less volatile hydrocarbons. Thus, the total charcoal extracts average 80 g/m³, the PUF compounds represent 4 /m³ and the particle hydrocarbons 0.7 g/m³. These latter airborne materials are essentially composed of petrogenic residues 0.6 g/m³ (aliphatic fraction) whereas the pyrolytic PAH only involve 0.08 g/m³.     

Brightness Reversion of Mechanical Pulps. Part XVII: Diffuse Reflectance Study on Brightness Stabilization by Additives Under Various Atmospheres

Brightness reversion of softwood (SW) and hardwood (HW) bleached chemithermomechanical pulps (BCTMP) with a 300–400nm light source under argon, oxygen, and air were studied in the absence and presence of UV-screens using UV–Vis reflectance difference spectroscopy. The UV-Vis difference absorption spectra of control SW and HW BCTMP testsheets indicate that as the concentration of atmospheric oxygen is increased, the absorption at max 360nm increases and a blue shift occurs. In all of the cases studied, brightness reversion was observed to occur under an argon atmosphere. The addition of benzophenone and benzotriazole additives to BCTMP testsheets resulted in a significant decrease in formation of chromophores absorbed at 400nm and 360nm. The possible mechanisms contributing to these effects are discussed in terms of the photoformation of lignin chromophoric structures.     

Recoil reactions of38Cl and128I in some heterocyclic systems

Halogen recoil following /n, / reaction has been studied in some heterocyclic systems. The organic yields are 60% for irradiation as solids: exceptions are dioxanide furoate /34%/ and 5-chloro isatoic anhydride /31%/. As solutions in 11 THF + benzene and 11 HTF+DMSO, these yields are lower by 10% and decrase further when only THF is the solvent. Mass-spectroscopy data revealed the possible fragmentation pattern.     

Study of the absorption spectra of the 4f electron transition of the Nd and Er complexes with 2-isobutylformyl-1,3-dione-indane in the presence of TX-100 and its analytical application

The absorption spectra of 4f electron transitions of the systems of neodymium and erbium with 2-isobutylformyl-1,3-dione-indane and TX-100 have been studied by normal and derivative spectrophotometry. Their molar absorptivities at the maximum absorption bands are about 7.2 (at 571 nm) times greater for neodymium and 13.1 (at 519 nm) times greater for erbium than those in the absence of the complexing agents. Use of second derivative spectra both eliminates the interference from other rare earths and increases the sensitivity from neodymium and erbium. Beers law is obeyed from 020 g/ml for neodymium and 025 g/ml for erbium. The relative standard deviations are 1.2% and 1.6% for 5.0 g/ml of neodymium and 8.0 g/ml of erbium, respectively. The detection limits (signal-to-noise ratio=2) are 0.14 g/ml and 0.20 g/ml. A method for the direct determination of neodymium and erbium in rare earth mixtures with good accuracy and selectivity is proposed.     

Formation of YAG from coprecipitated yttrium aluminium hydroxides

Thermal decomposition of the amorphous coprecipitate of yttrium and aluminium hydroxides forming yttrium aluminium garnet has been investigated employing thermal analyses, X-ray diffraction and IR spectroscopy. On heating, the coprecipitate progressively loses water forming a stable but highly disordered hydroxy garnet which crystallizes at 1180 K and decomposes to YAG at 1290 K. Nucleation of the crystalline phase appears to begin at 800 K.The authors thank Dr. P. V. Ravindran of the Analytical Chemistry and Shri N. K. Kulkarni of the Fuel Chemistry Divisions of BARC for their assistance in the thermoanalytical experiments.     

The glyceride complex of the seed oil ofOnopordum acanthiium

Summary The complex mixture of glycerides of a seed oil containing oxidized aryl radicals in the triglycerides (10 groups of glycerides) has been separated for the first time. New groups of monohydroxyacyl triglycerides (oxoacyl, 0.1% of the oil, and hydroperoxyacyl, 0.1%) and di(oxyacyl)triglycerides (epoxacyl-hydroxyacyl, 0.36%) have been detected and isolated.A new -oxodienoic acid has been found for which the following structural formula is proposed as the most probable: 11-oxooctadeca-cis-9,cis-12-dienoic acid.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 699–707, November–December, 1978. Original article submitted June 27, 1978.     

Vinyl Ethers Containing an Epoxy Group: XXI. Synthesis and Acid-Catalyzed Cyclization of 1-[ω-(Vinyloxy)alkoxy]-3-(2-propynyloxy)-2-propanols- A Simple Route to 2-Propynyloxymethyl-Substituted Cyclic Polyethers

Base-catalyzed reaction of 2-[-(vinyloxy)alkoxy]methyloxiranes with 2-propynyl alcohol (3 wt % of t-BuOK, 60-85°C, 3-12 h) afforded first reperesentatives of the 1-[-(vinyloxy)alkoxy]-3-(2-propynyloxy)-2-propanol series in up to 99% yield. Treatment of 1-[2-(vinyloxy)ethoxy]- and 1-[2-(vinyloxy)ethoxyethoxy]-3-(2-propynyloxy)-2-propanols with trifluoroacetic acid (0.5 wt. %) in dry diethyl ether resulted in cyclization with formation of up to 96% of (2-methyl-1,3,6-trioxocan-4-yl)methyl- and (2-methyl-1,3,6,9-tetraoxacycloundecan-4-yl)methyl 2-propynyl ethers.     

Über einige Komplexboride von Übergangsmetallen

Zusammenfassung Dreistofflegierungen in dem Kombinationen {Mo, W}-{Fe, Co, Ni}-B; {V, Nb, Ta, Mo, W}-B-Al werden vornehmlich auf die Existenz von Komplexboriden hin untersucht. Die isotypen Phasen Mo₂CoB₂, Mo₂NiB₂, W₂FeB₂, W₂CoB₂ und W₂NiB₂ sind strukturell mit Mo₂FeB₂ verwandt, aber doch von dieser Phase verschieden. Gefunden werden außerdem die isotypen Phasen MoCoB und WCoB. Das Problem der -Phase wird diskutiert. In manchen Fällen tritt ein Zwischenzustand auf, der vermutlich durch Stapelfehler einer Unterzelle (c/3 in hexagonaler Aufstellung) hervorgerufen wird. Neben dem Auftreten ternärer Phasen bei Nb-B-Al und Ta-B-Al wird eine ausgeprägte Mischphasenbildung: (Nb, Al)B₂ und (Ta, Al)B₂ beobachtet. Der Dreistoff: Mo-B-Al ist durch die ternäre Phase MoBAl gekennzeichmet, ferner tritt der durch Al stabilisierte CrB-Typ auf (Mo_0,45B_0,50Al_0,05). Die Gleichgewichtsverhältnisse in denT-B-Al-Dreistoffen werden abgeschätzt.

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Alloys of the combinations {Mo, W}-{Fe, Co, Ni}-B, {V, Nb, Ta, Mo, W}-B-Al have been examined with respect to the existence of complex borides. The phases of the approximate formula Mo₂CoB₂, Mo₂NiB₂, W₂FeB₂, W₂CoB₂ and W₂NiB₂ have been found to be isotypic. They do however not correspond to Mo₂FeB₂ having U₃Si₂ structure. Two other complex borides of formula MoCoB and WCoB have been detected having the same crystal structure. The problem of the -phases which partially contain boron will be discussed considering the supposedly occurring stacking faults of a subcell unit (c=c/3 for hexagonal symmetry). Besides formation of ternary compounds for: Nb-B-Al and Ta-B-Al an extended solid solution (Nb, Al)B₂ and (Ta, Al)B₂ has been observed. The Mo-B-Al-system is characterized by the ternary phase of formula MoBAl. Mo-monoboride having CrB-type has been found to be stabilized by a small amount of Al, thus Mo_0,45B_0,50Al_0,05 being formed. The phase equilibria within the ternary systems have been established for the major part.

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Mit 4 Abbildungen     

Simple screening method for the fast determination of clenbuterol in animal feeds

Summary A simple method for the determination of clenbuterol is described. It is extracted from the sample at pH 3 and then at pH 11, followed by partitioning the analyte into water at pH 3 and reextraction into ethyl acetate at pH 9. Clenbuterol is oxidized with KMnO₄ to clenbuteron for GC-determination. Recoveries for 0.01– 1.0 mg/kg were between 70% and 110% (standard deviation ±14%, n = 18).

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Eine einfache Screening-Methode zur schnellen Bestimmung von Clenbuterol in tierischen Futtermitteln

     

Kinetic dual standard additions method for the determination of two mutually interfering analytes: Molybdate and tungstate

A kinetic dual standard additions method for determination of two mutually interfering analytes is proposed. The deviations of absorbance from additivity in kinetic systems, caused by synergistic effects of catalysts, are compensated with the defined synergistic catalytic coefficient. The hydrogen peroxide-iodide kinetic reaction catalysed by molybdate and tungstate was studied with the stopped-flow injection technique and the conditions for simultaneous determination of Mo and W established. The molybdenum and tungsten contents in different samples were determined with recoveries of 97.6 102.1% and 96.9 98.6%, and relative standard deviations of 2.3 3.4% and 1.6 2.6%, respectively.