Selective and sensitive voltammetric sensor based on modified multiwall carbon nanotubes paste electrode for simultaneous determination of l-cysteine and folic acid

This paper reports the selective and sensitive voltammetric determination of l-cysteine in the presence of folic acid using ethynylferrocene modified carbon nanotubes paste electrode in 0.1 M phosphate buffer solution (pH 7.0). Using square wave voltammetry, we could measure l-cysteine and folic acid in one mixture independently from each other by a potential difference of about 410 mV for the first time. Square wave voltammetric peak current of l-cysteine and folic acid increased linearly with their concentrations in the ranges of 0.2–250.0 and 1.0–500.0 μmol?L^?1, respectively. The detection limits of 0.07 and 0.6 μmol?L^?1 were achieved for l-cysteine and folic acid, respectively. The proposed voltammetric sensor was successfully applied to the determination of l-cysteine and folic acid in real samples.     

Determination of relaxation times for iron ions from Mössbauer data

An analysis is made of the experimental results ofBruckner et al., in terms of the relaxation model ofvan der Woude andDekker, and a comparison is made with Wegener's analysis. The two approaches lead in principle to relaxation parameters independent ofH/T and a discrepancy reported byWegener does not exist.     

Magnetic hyperfine field at Cr site in AgCrO2 given by Perturbed angular correlations

This work presents an electric field gradient and magnetic hyperfine field study, in the AgCrO₂ multiferroic with triangular spin lattice. The temperature dependence of the electric field gradient (efg) and magnetic hyperfine field (mhf) at Cr site was studied at isolde via perturbed angular correlation measurements with the ¹¹¹In probe, at room temperature and below the Néel temperature (T?≤?21 K) down to 12 K. The results show the presence of two distinct local environments. One axial symmetric efg with a very low mhf, and a non axially symmetric efg with a much higher one. The temperature dependences of mhf magnitude and of the angle between the mhf and the principle component of the efg are investigated.     

The Strong Interaction at the Collider and Cosmic-Rays Frontiers

First data on inclusive particle production measured in proton–proton collisions at the Large Hadron Collider (LHC) are compared to predictions of various hadron-interaction Monte Carlos (qgsjet, epos and sibyll) used commonly in high-energy cosmic-ray physics. While reasonable overall agreement is found for some of the models, none of them reproduces consistently the ${\sqrt{s}}$ evolution of all the measured observables. We discuss the implications of the new LHC data for the modeling of the non-perturbative and semihard parton dynamics in hadron–hadron and cosmic-rays interactions at the highest energies studied today.     

Dynamics of impurity spin above the Kondo temperature

The dynamics of impurity spin contained by nonmagnetic host metal is investigated theoretically. The pseudofermion representation proposed byAbrikosov is applied to impurity spin. The calculations are carried out keeping only the leading logarithmic terms in any order of the perturbation theory. This approximation is adequate only above the Kondo temperature. Abrikosov's method is slightly modified to treat the spin dynamics. The real and the imaginary part of the pseudofermion self-energy is calculated. The imaginary part of the self-energy satisfies a simple relation which holds between the electron and pseudofermion self-energies. The decrease in the effective gyromagnetic factor is determined, which shows how the spin compensated state begins to form at low temperature. The first terms of the power series of the static susceptibility calculated from the pseudofermion Green function are in agreement with the results of the previous perturbative calculations given by e.g.Yosida andOkiji. The spectral function of the pseudofermion propagator is discussed in details. It has a long tail at large positive energies and satisfies the sum rule \(\int\limits_{{}^\_\infty }^\infty {d\omega \rho (\omega ) = 1} \) . The dynamic susceptibility and other physical quantities will be presented in the second part of this paper.     

MC-Simulation of the Transverse Double Spin Asymmetry for RHIC

We give a leading order estimate of the hadronic transverse double spin asymmetry in the Drell-Yan process at RHIC using Sphinx tt,anew polarized version ofthe Monte Carlo Pythia 5.6. We also calculate the statistical error to next to leading order with Pythia 5.7. Both quantities are of the same order if one assumes that the transversity weighted parton distributions equal the helicity weighted ones at some low perturbative scale Q ₀ ² .     

Polynomial behaviour of scattering amplitudes at fixed momentum transfer in theories with local observables

It is shown that, in theories of exactly localized observables, of the type proposed byAraki andHaag, the reaction amplitude for two particles giving two particles is polynomially bounded ins for fixed momentum transfert<0. The proof does not need observables localized in space-time regions of arbitrarily small volume, but uses relativistic invariance in an essential way. It is given for the case of spinless neutral particles, but is easily extendable to all cases of charge and spin. The proof can also be generalized to the case of particles described by regularized products $$\int {\varphi (x_1 ,..., x_n ) \phi _1 } (x - x_1 ) ... \phi _n (x - x_n )dx_1 ...dx_n $$ ofWightman orJaffe fields.     

Das kritische Magnetfeld Hc∥ von dünnen supraleitenden Filmen

Thin superconducting films in a surface parallel magnetic field are considered, assuming that the order parameter is constant in space. Without any further restrictions on the film thickness,a, an equation for the critical field is derived. In the clean limit, this equation is valid only in the vicinity of T_c, but in the dirty limit it is valid for all temperatures. Our results, for specular reflection, are identical with those obtained byThompson andBaratoff. But for not too thin films we find essential differences between the results for specular and for diffus reflection. For very thin films (a?v/2πT _c), considered in detail byde Gennes andTinkham and byShapoval, our results are in agreement with those obtained byShapoval. In the opposit limit (a?v/2π T _c), the most essential corrections to the Ginzburg-Landau result obtained byLüders are rederived.     

Synthesis and anti-cancer activity of a glycosyl library of \varvec{N}-acetylglucosamine-bearing oleanolic acid

N-Acetylglucosamine-bearing triterpenoid saponins (GNTS) were reported to be a unique type of saponins with potent anti-tumor activity. In order to study the structure–activity relationship of GNTS, 24 oleanolic acid saponins with ( $1 \rightarrow 3$ )-linked, ( $1\rightarrow 4$ )-linked, ( $1\rightarrow 6$ )-linked $N$ -acetylglucosamine oligosaccharide residues were synthesized in a combinatorial and concise method. The cytotoxicity of these compounds toward the leukemia cell line HL-60 and the colorectal cancer cell line HT-29 could not be improved. Half maximal inhibition below $10\,\upmu \hbox {M}$ was achieved in one single case. The study revealed that the activity decreased following the order of $3^{\prime }>4^{\prime }>6^{\prime }$ glycosyl modifications. GNTS that incorporated (d/l)-xylose and l-arabinose at positions $3^{\prime }$ and $4^{\prime }$ were more potent than those bearing other sugars.     

Spezifischer Energieverlust von schweren Ionen in Aluminium,Silber und Gold

Using a Cf²⁵²-fission source and two semiconductor detectors in 180°-position the specific energy loss of heavy ions in A1-, Ag-, and Au-foils was measured. The agreement with the results ofMoak andBrown, and ofKahn andForgue is better than 15%. The energy loss predicted byLindhard is 10–25% lower than the measured values. A better agreement — especially for absorbers with low atomic numberZ — is achieved by a semiempirical formula proposed byMünzel.     

Messung der Oberflächenspannung der flüssigen Alkalimetalle im Ultra-Hochvakuum

The surface tension of highly purified, liquid alkali metals and its temperature dependence have been measured under ultra-high-vacuum conditions. The results obtained for sodium agree with those ofAddison andTaylor as well as with theoretical values given byStratton andZadumkin, whereas the results on K, Rb and Cs are different from all values obtained hitherto by others. The temperature dependence of surface tension of all alkalis follows theoretical predictions. There is no observable influence of Ar and O₂ on the surface tension up to 10^?3 Torr.     

Energie-Relaxation warmer Ladungsträger in Germanium und Silizium

Experimental data on warm carrier energy relaxation times in germanium and silicon are reported. Measurements were done by the method of harmonic mixing of microwaves 1 in the temperature range between 77 and 200 °K. Relaxation times obtained forn-type germanium are in agreement with data reported byMorgan 2 as well as that ofSeeger 3 andGibson et al. 4. Measured energy relaxation times forp-type germanium as well as forn- andp-type silicon are reported here for the first time. A qualitative interpretation is given in terms of scattering by acoustic and optical phonons.     

The determination by an independent method ofP k electron capture probabilities in133Ba and139Ce decays gamma decay of133Ba

The electron capture decays of¹³³Ba (10.4 y) and¹³⁹Ce (140 d) were investigated with high resolution Ge(Li) detectors. By x-ray — γ-ray coincidences values of the quantityP _k ω _k ? _k for various transitions in the decay of¹³³Ba and¹³⁹Ce are obtained. The factor ω _k ? _k was measured independently by means ofK-conversion electron-K x-ray coincidences and was then used to determineP _k , theK-capture probability. The independent measurement of the product ω _k ? _k , together with recent accurate values of ω _k , provides a new method for the accurate calibration of semiconductor x-ray detectors. In the decay of¹³⁹Ce, a value ofP _k =0.78±0.03 is found (where the error represents twice the standard deviation) from whichQ _ec =326 _?30 ⁺⁷⁰ keV to the¹³⁹La ground-state is found by use of theory. In¹³³Ba decay, values are found ofP _k 1=0.72±0.04 for theEC transition to the 437 keV level in¹³³Cs,P _k 2=0.80±0.07 to the 384 keV level, and from an independent measurement, the ratioP _k 1/P _k 2=0.87±0.07. From these results the ground-state value ofQ _ec =522 _?10 ⁺²⁰ keV is derived from theory for¹³³Ba decay. The gamma spectrum of¹³³Ba also was remeasured. From the present gamma intensities and previous conversion electron intensities, new values forK-shell conversion coefficients are obtained. Previously reported γ-rays at 35 and 391 keV are not confirmed.     

The effect ofs-d exchange interaction on the nuclear spin relaxation in dilute alloys

The effect ofs-d exchange interaction on the relaxation rate of host nuclear spins has been investigated in dilute magnetic alloys. The leading logarithmic corrections to the Korringa relaxation rate have been calculated together with some lower order logarithmic terms to avoid a divergence at the Kondo temperature (T _k ). The obtained formulae are valid at and aboveT _k and in weak or strong magnetic fields (ω _i ?T or ω _i ?T, respectively, where ω _i is the Larmor frequency of the impurity spin). In second order of the perturbation theory our result reproduces that obtained by Giovannini and Heeger apart from a numerical factor of the order of unity and from some contribution of order (J/? _f )².     

Laser assisted decay spectroscopy at the CRIS beam line at ISOLDE

The new collinear resonant ionization spectroscopy (Cris) experiment at Isolde, Cern uses laser radiation to stepwise excite and ionize an atomic beam for the purpose of ultra-sensitive detection of rare isotopes and hyperfine structure measurements. The technique also offers the ability to purify an ion beam that is contaminated with radioactive isobars, including the ground state of an isotope from its isomer. A new program using the Cris technique to select only nuclear isomeric states for decay spectroscopy commenced last year. The isomeric ion beam is selected using a resonance within its hyperfine structure and subsequently deflected to a decay spectroscopy station. This consists of a rotating wheel implantation system for alpha and beta decay spectroscopy, and up to three high purity germanium detectors for gamma-ray detection. This paper gives an introduction to the Cris technique, the current status of the laser assisted decay spectroscopy set-up and recent results from the experiment in November 2011.     

MCPLOTS: a particle physics resource based on volunteer computing

The mcplots.cern.ch web site (mcplots) provides a simple online repository of plots made with high-energy-physics event generators, comparing them to a wide variety of experimental data. The repository is based on the hepdata online database of experimental results and on the rivet Monte Carlo analysis tool. The repository is continually updated and relies on computing power donated by volunteers, via the lhc@home 2.0 platform.     

Simulating spin-\frac{3}{2} particles at colliders

Support for interactions of spin- $\frac{3}{2}$ particles is implemented in the FeynRules and ALOHA packages and tested with the MadGraph 5 and CalcHEP event generators in the context of three phenomenological applications. In the first, we implement a spin- $\frac{3}{2}$ Majorana gravitino field, as in local supersymmetric models, and study gravitino and gluino pair-production. In the second, a spin- $\frac{3}{2}$ Dirac top-quark excitation, inspired from compositeness models, is implemented. We then investigate both top-quark excitation and top-quark pair-production. In the third, a general effective operator for a spin- $\frac{3}{2}$ Dirac quark excitation is implemented, followed by a calculation of the angular distribution of the s-channel production mechanism.     

Multiferroic properties of Tb-doped BiFeO3 nanowires

The aim of this study was to investigate the protective role of quercetin and/or l-arginine against the cardiotoxic potency of zinc oxide nanoparticle (ZnO-NP)-induced cardiac infarction. ZnO-NPs (50 nm) were administered orally at either 600 mg or 1 g/kg body weight for 5 consecutive days. The results revealed that co-administration of quercetin and/or l-arginine (each 200 mg/kg body weight) daily for 3 weeks to rats intoxicated by either of the two doses markedly ameliorated increases in serum markers of cardiac infarction, including troponin T, creatine kinase-MB, and myoglobin, as well as increases in proinflammatory biomarkers, including tumor necrosis factor-α, interleukin-6, and C-reactive protein, compared with intoxicated, untreated rats. Each agent alone or in combination also successfully modulated the alterations in serum vascular endothelial growth factor, cardiac calcium concentration, and oxidative DNA damage as well as the increase in the apoptosis marker caspase 3 of cardiac tissue in response to ZnO-NP toxicity. In conclusion, early treatment with quercetin and l-arginine may protect cardiac tissue from infarction induced by the toxic effects of ZnO-NPs.     

Nuclear larmor precession of the 14 keV state of57Fe in α-iron following the reaction56Fe (d,p)57Fe

The spin precession of the 14 keV state of⁵⁷Fe, excited by the⁵⁶Fe(d,p) reaction was observed in ferromagnetic Fe. The data yield a magnetic field of ? 330±4 kG and a relaxation time τ _r > 500 ns at room temperature.     

PENTATRAP: a novel cryogenic multi-Penning-trap experiment for high-precision mass measurements on highly charged ions

The novel five-Penning-trap mass spectrometer Pentatrap is developed at the Max-Planck-Institut für Kernphysik (MPIK), Heidelberg. Ions of interest are long-lived highly charged nuclides up to bare uranium. Pentatrap aims for an accuracy of a few parts in 10¹² for mass ratios of mass doublets. A physics program for Pentatrap includes Q-value measurements of β-transitions relevant for neutrino physics, stringent tests of quantum electrodynamics in the regime of extreme electric fields, and a test of special relativity. Main features of Pentatrap are an access to a source of highly charged ions, a multi-trap configuration, simultaneous measurements of frequencies, a continuous precise monitoring of magnetic field fluctuations, a fast exchange between different ions, and a highly sensitive cryogenic non-destructive detection system. This article gives a motivation for the new mass spectrometer Pentatrap, presents its experimental setup, and describes the present status.