TheA-scaling of the multiplicity distributions ofπ ′,K − and\bar P interactions with nuclei at 40 GeV/c

The multiplicity distributions of charged particles produced from π^?,K ^? and \(\bar p\) interactions with the nuclei Li, C, S, Cu, CsI, Pb at 40 GeV/c were studied. It was found that the linear relationD=a〈n〉+b is satisfied for the distributions of different kinds of secondary particles including knocked out protons. Consequently, the use of the scaling variablez′=(an+b)/(a〈n〉+b) ensures the scaling of the distributions with respect to the mass numberA at least up to the second moment.     

Neutral strange particle production in high transverse momentum π− nucleus interactions at ∼40 GeV/c

Measurements ofK _s ⁰ , Λ and \(\bar \Lambda \) production in π^? nucleus (C, Cu, Pb) interactions are presented. The experiment was carried out with the streamer chamber spectrometer RISK using a π^? beam of ～40 GeV/c and a trigger requiring a secondary charged particle with transverse momentum above 1.1 GeV/c. Production cross sections, relative production rates and distributions of Feynmanx and transverse momentum squared as well as correlations between theV ⁰ and the trigger particle are presented. The results are compared and found to be in agreement withK _s ⁰ , Λ and \(\bar \Lambda \) data from untriggered π^? p and π^? C interactions, except for the relative production rate of antilambdas which is about to times larger in high-p _t collisions. Our results can be well interpreted within the dual topological unitarization model.     

The thermal decomposition of hydrocarbons. Part 2. Alkylaromatic hydrocarbons: Alkylbenzenes

The pyrolysis of the n-alkylbenzenes is reviewed with emphasis on the radical chain mechanism and on the reactions of the intermediate radicals. The effects of the experimental conditions and conversion on the types and distribution of the final products are also evaluated. The Arrhenius rate parameters are summarized for both the elementary steps and the overall decomposition reactions.     

The nucleation rate of crystalline ice in amorphous solid water

The kinetics of crystalline ice nucleation and growth in nonporous, molecular beam deposited amorphous solid water (ASW) films are investigated at temperatures near 140 K. We implement an experimental methodology and corresponding model of crystallization kinetics to decouple growth from nucleation and quantify the temperature dependence and absolute rates of both processes. Nucleation rates are found to increase from approximately 3x10(13) m(-3) s(-1) at 134 K to approximately 2x10(17) m(-3) s(-1) at 142 K, corresponding to an Arrhenius activation energy of 168 kJ/mol. Over the same temperature range, the growth velocity increases from approximately 0.4 to approximately 4 A s(-1), also exhibiting Arrhenius behavior with an activation energy of 47 kJ/mol. These nucleation rates are up to ten orders of magnitude larger than in liquid water near 235 K, while growth velocities are approximately 10(9) times smaller. Crystalline ice nucleation kinetics determined in this study differ significantly from those reported previously for porous, background vapor deposited ASW, suggesting the nucleation mechanism is dependent upon film morphology.     

Peroxidase-like activity of magnetoferritin

Magnetoferritin is a spherical biomacromolecule with a diameter of about 12 nm. It consists of a protein shell composed of apoferritin that is surrounding magnetic nanoparticles of magnetite (Fe₃O₄) or maghemite (γ-Fe₂O₃). Magnetoferritins with various iron content (loading factor) were synthetically prepared and their peroxidase-like activities studied via the oxidation of the chromogenic substrate N,N-diethyl-p-phenylenediamine sulfate by hydrogen peroxide to give a purple product with an absorption maximum at 551 nm. Magnetoferritin with higher loading factor exhibits a higher peroxidase-like activity. The catalytic activity was successfully applied to the determination of hydrogen peroxide in the 5.8 to 88.2 mM concentration range.

Negative refraction

Light bends the wrong way in materials where both ε and μ are negative as was pointed out in 1968, but the absence of natural materials with this property led to neglect of the subject until 1999 when it was shown how to make artificial materials, metamaterials, with negative μ. The rapid advance of the subject since that date, both in theory and experiment, is reflected in the exponential growth of publications now at the 200 per year level and still growing. This interest is explained by the sudden availability of a qualitatively different class of electromagnetic materials combined with the quite startling properties which these materials appear to have; all of which provokes debate as each new facet of their behaviour is revealed. Experiment has been vital to resolution of controversy and has chiefly been in the microwave region of the spectrum though there is potential in the optical region currently being explored by several groups.     

Magnetic techniques for the detection and determination of xenobiotics and cells in water

Magnetic techniques based on the application of magnetic nanoparticles and microparticles and films have been successfully used for the determination and detection of different types of xenobiotics (e.g. herbicides, insecticides, fungicides, aromatic and polyaromatic hydrocarbons, pentachlorophenol and heavy metal ions) as well as viruses, microbial pathogens and protozoan parasites in water samples. Preconcentration of xenobiotics from large volumes of samples can be performed using magnetic solid-phase extraction, stir-bar sorptive extraction and related procedures. This review provides basic information about these techniques. Published examples of successful applications document the importance of these simple and efficient procedures employing magnetic materials.     

Similarities in the Cp/T3 peaks in amorphous and crystalline metals

A low-temperature peak in C(p)/T(3) vs is ubiquitous to glasses. It arises from an abundance of low-frequency vibrations, the origin of which remains unclear. A comparable C(p)/T(3) vs peak is observed in crystals due to the dispersion of acoustic phonons and/or the excitation of optical phonons. We compared the C(p)/T(3) vs peaks in metallic and oxide glasses to elemental crystals by analyzing specific heat, phonon density of states, and elastic constant data. We observe no clear distinction in the peak temperature or amplitude between metallic glasses and crystals. Surprisingly, the peak is larger in single crystal Pd(40)Cu(40)P(20) than in glassy Pd(40)Cu(40)P(20).     

A quantitative nonlinear strong ergodic theorem for Hilbert spaces

We give a quantitative version of a strong nonlinear ergodic theorem for (a class of possibly even discontinuous) selfmappings of an arbitrary subset of a Hilbert space due to R. Wittmann and outline how the existence of uniform bounds in such quantitative formulations of ergodic theorems can be proved by means of a general logical metatheorem. In particular these bounds depend neither on the operator nor on the initial point. Furthermore, we extract such uniform bounds in our quantitative formulation of Wittmann?s theorem, implicitly using the proof-theoretic techniques on which the metatheorem is based. However, we present our result and its proof in analytic terms without any reference to logic as such. Our bounds turn out to involve nested iterations of relatively low computational complexity. While in theory these kind of iterations ought to be expected, so far this seems to be the first occurrence of such a nested use observed in practice.     

Order-parameter coupling in the improper ferroelectric lawsonite

Low-temperature specific heat and thermal expansion measurements are used to study the hydrogen-based ferroelectric lawsonite over the temperature range 1.8 K ≤ T ≤ 300 K. The second-order phase transition near 125 K is detected in the experiments, and the low-temperature phase is determined to be improper ferroelectric and co-elastic. In the ferroelectric phase T ≤ 125 K, the spontaneous polarization P(s) is proportional to (1) the volume strain e(s), and (2) the excess entropy ΔS(e). These proportionalities confirm the improper character of the ferroelectric phase transition. We develop a structural model that allows the off-centering of hydrogen positions to generate the spontaneous polarization. In the low-temperature limit we detect a Schottky anomaly (two-level system) with an energy gap of Δ ～ 0.5 meV.