Gain of a compressed DT fuel statistically ignited by a multispark assembly

Most of the current inertial confinement fusion (ICF) schemes are based on the ignition of a high-density DT fuel by a single, high-temperature spherical hot spot (the spark). The spark is self-generated by the implosion process, which is used to bring the fuel to high density. To start ignition the spark has to be dimensioned in such a way that the ion temperature would be greater than 5–7 keV, and that the spark radius would be greater than the α-particle range. A spark with these features is indicated as supercritical. In the scheme based on self-generated spark, ignition can fail to occur when the produced spark strongly deviates from spherical shape, which can make all the surface losses highly relevant. High deformation, or even spark splitting, can occur due to the amplification of initial deviations from spherical shape by hydrodynamic instabilities (or by secular growth) during the implosion process. In principle, ignition can be recovered if the implosion is designed in such a way as to make supercritical at least one of the portions of hot fuel which are produced in this way near stagnation. As a general trend, more compressed final assemblies are required. In this paper we present fuel gain calculations (Gain = Thermonuclear energy/Energy in the compressed fuel) for DT assemblies ignited at the end of an implosion process by a supercritical spark statistically created within a cluster of many subcritical sparks. It is assigned the total number of sparks and the probability of having at least one of them supercritical. As a function of these quantities we calculate, in the framework of an isobaric model, the average thermal energy associated with the spark assembly. The same model is also used to evaluate, by statistical arguments, the areal mass, the burn fraction, and the system’s total fuel gain. It is found that the energy distribution function of the sparks is influenced only by a single global parameter, in which the assigned ignition probability and the number of sparks are also represented. Compared to the single central-spark approach, being the final states with allowed inner turbulence, the multispark scheme is characterized by relaxed initial symmetry requirements. For multispark systems we can realistically consider the achievement of fuel gains comparable or greater than those typical of the single-spark approach, when evaluated for currently accepted spark convergence ratios. With regard to the single spark case, higher cold fuel densities are needed, as expected (typically 2×–3×, for the same gain, depending on the energy distribution function). Zh. éksp. Teor. Fiz. 113, 805–815 (March 1998) Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor.     

Conformation-Odor Relationships in Norlabdane Oxides

Conformational factors have been found responsible for the dramatic change in odor between (?)-deoxyambreinolide ( 12 ) and its (+)-epi derivative 13 . The presumably molecular event during the receptor interaction has been simulated by the diastereoisomeric 11-methyl-ambrox derivatives 3 and 5 as model compounds.     

An electrolytic conductivity study of tetraalkylammonium perchlorates in 1,3-dimethylethyleneurea and 1,3-dimethylpropyleneurea at 25°C

A series of four tetraalkylammonium perchlorates (methyl through butyl) in 1,3-dimethylethyleneurea and 1,3-dimethylpropyleneurea were investigated conductimetrically over the concentration range 1–100×10^–4 M. All data were analyzed by the Fuoss-Shedlovsky, the Fuoss-Onsager, and the full and expanded Pitts equations. Analysis by the full and expanded Pitts equations yielded largerK _A and ion-size parameters as well as lower ₀ values than the Fuoss-Onsager analysis. Data analyzed by the expanded Pitts equation yielded slightly higher ₀ values, smallerK _A values, and smaller distance parameters than the full Pitts anlysis.     

Capillary GC-MS — Stable isotope dilution analysis of methylmalonic acid in plasma: A candidate reference method for the diagnosis and the follow-up of methylmalonic acidaemias

Summary Because methylmalonic acid (MMA) accumulates in the body fluids of patients suffering from inherited metabolic disorders involving its pathway, the quantitation of this metabolite is not only fundamental to diagnosis but is also important in the follow-up of affected patients under treatment.We describe the method set up and used in our laboratory for the measurement of MMA in body fluids and propose its application to plasma as the reference method for the biochemical diagnosis and follow-up of methylmalonic acidaemias.     

Gluon andq\bar q mixing in theη−η ′−G(≡i(1440))system

A mixing scheme among three pseudoscalar mesons η, η′ and τ(1440) is proposed in order to analyze their \(q\bar q\) and gluonic components. Inequalities follow from requiring the consistency of the scheme and the range permitted for the mass of the pure gluonic state (glueball) turns out to be rather small. The resulting picture is in good agreement with the overall phenomenology and with the (rather scarce) data on the subject.     

Plasma spectrometry for elemental speciation and characterization in beverages

A review is presented on recent applications of plasma spectrometric techniques for speciation analysis in beverages. The 3 most common ways of characterizing beverages in addition to elemental speciation are also discussed: total element analysis, isotope ratio, and statistical characterization. To date, most of the elemental characterization in beverages with plasma techniques has been performed in the statistical evaluation of wines and in teas. However, despite the increasing interest in elemental speciation, most of the plasma-based techniques in beverage studies are used for total metal detection and the full capabilities of inductively coupled plasma techniques have yet to be realized.     

Hydrolysis of proteins with methanesulfonic acid for improved HPLC-ICP-MS determination of seleno-methionine in yeast and nuts

In this work, the use of methanesulfonic acid for protein hydrolysis is proposed for evaluation of Se-methionine in yeast, Brazil nuts, and possibly other selenium-rich biological samples. The hydrolysis was carried out by heating the sample with 4 mol L(-1) acid at reflux for 8 h. Two chromatographic techniques (size-exclusion and ion-pairing) coupled with ICP-MS detection were used to compare the release of Se-methionine from proteins by enzymatic (proteinase K, protease XIV) and acid hydrolyses. A more efficient liberation of Se-methionine was observed by acid hydrolysis. For quantification, the sample extracts were introduced onto a C8 Alltima column, and the separation was achieved with a mobile phase containing 5 mmol L(-1) hexanesulfonic acid in citrate buffer (pH 4.5)/methanol (95:5). The results obtained by standard addition showed 816+/-17 micro g g(-1) and 36.2+/-1.5 micro g g(-1) of selenium in the form of Se-methionine in yeast and nuts, respectively (65% and 75% of total selenium).     

Polygones de Hodge,de Newton et de l’inertie modérée des représentations semi-stables

Dans cette note, on associe à chaque représentation p-adique semi-stable un polygone obtenu à partir des poids de l’inertie modérée de la semi-simplifiée modulo p, et on compare dans certains cas la position relative de ce polygone par rapport aux polygones de Hodge et de Newton.