Beam dynamics of 20 MeV MIRRORCLE-type tabletop storage ring

An experimental study on beam dynamics in MIRRORCLE-20, a tabletop storage ring of 15 cm orbit radius, was performed. Measurement of the infrared (IR) synchrotron light is the tool of this study. The IR emission is enhanced by a circular optics, named photon storage ring (PhSR), placed around the electron orbit, and is collected by a magic mirror associated with two plane mirrors in the storage ring. The measured average IR power in mid-IR region (λ < 50 μm) is ～59 mW. The observed stored beam current is about 1.2 A at maximum, which represents a record for a storage ring. The observed beam size is about 74 × 3 mm². We conclude that this very long beam size is due to the large betatron oscillation of 2/3 resonance injection.     

Effect of Zn substitution on the magnetic properties of Mg1−xZnxFe2O4 ferrites

Polycrystalline Mg_1−xZn_xFe₂O₄ (x=0.0–0.6) ferrites have been prepared using solid-state reaction technique. The X-ray diffraction analysis revealed that the samples crystallize in a single-phase cubic spinel structure. The lattice parameter increases linearly with increase in zinc content obeying Vegard's law. The continuous decrease in Curie temperature (T_c) with an increase in Zn content is attributed to the weakening of A–B exchange interaction. Saturation magnetization (M_s) and magnetic moment are observed to increase up to x=0.4, and thereafter decrease due to the spin canting in B-sites. The initial permeability is found to increase with the addition of Zn²⁺ ions but the resonance frequency shifts towards the lower frequency.     

Modulation instability of lower hybrid waves leading to cusp solitons in electron–positron(hole)–ion Thomas Fermi plasma

Following the idea of three‐wave resonant interactions of lower hybrid waves, it is shown that quantum‐modified lower hybrid (QLH) wave in electron–positron–ion plasma with spatial dispersion can decay into another QLH wave (where electron and positrons are activated, whereas ions remain in the background) and another ultra‐low frequency quantum‐modified ultra‐low frequency Lower Hybrid (QULH) (where ions are mobile). Quantum effects like Bohm potential and Fermi pressure on the lower hybrid wave significantly reshaped the dispersion properties of these waves. Later, a set of non‐linear Zakharov equations were derived to consider the formation of QLH wave solitons, with the non‐linear contribution from the QLH waves. Furthermore, modulational instability of the lower hybrid wave solitons is investigated, and consequently, its growth rates are examined for different limiting cases. As the growth rate associated with the three‐wave resonant interaction is generally smaller than the growth associated with the modulational instability, only the latter have been investigated. Soliton solutions from the set of coupled Zakharov and NLS equations in the quasi‐stationary regime have been studied. Ordinary solitons are an attribute of non‐linearity, whereas a cusp soliton solution featured by nonlocal nonlinearity has also been studied. Such an approach to lower hybrid waves and cusp solitons study in Fermi gas comprising electron positron and ions is new and important. The general results obtained in this quantum plasma theory will have widespread applicability, particularly for processes in high‐energy plasma–laser interactions set for laboratory astrophysics and solid‐state plasmas.     

Dodecaphenyltetracene

Dodecaphenyltetracene ( 4 ), the largest perphenylacene yet prepared, was synthesized from known tetraphenylfuran, hexaphenylisobenzofuran, and 1,2,4,5‐tetrabromo‐3,6‐diphenylbenzene in three steps. The X‐ray structure of the deep red, highly luminescent 4 shows it to be a D₂‐symmetric molecule with an end‐to‐end twist of 97°. The central acene is encapsulated by the peripheral phenyl substituents, and as a result, the molecule is relatively unreactive and even displays reversible electrochemical oxidation and reduction.     

Carbon sequestration and estimated carbon credit values as measured using <Superscript>13</Superscript>C labelling and analysis by means of an optical breath test analyser

Recent developments in optical systems (isotope-selective non-dispersive infrared spectrometry) for breath testing have provided a robust, low-cost option for undertaking ¹³C analysis. Although these systems were initially developed for breath testing for Helicobacter pylori, they have an enormous potential as a soil science research tool. The relatively low cost of the equipment, US$15,000–25,000, is within the research budgets of most institutes or universities. The simplicity of the mechanisms and optical nature mean that the equipment requires relatively low maintenance and minimal training. Thus methods were developed to prepare soil and plant materials for analysis using the breath test analyser. Results that compare conventional mass spectrometric methods with the breath test analyser will be presented. In combination with simple ¹³C-plant-labeling techniques it is possible to devise methods for estimating carbon sequestration under different agronomic management practices within a short time frame. This enables assessment of the carbon credit value of a particular agronomic practice, which can in turn be used by policy makers for decision-making purposes. For global understanding of the effect of agricultural practices on the carbon cycle, data are required from a range of cropping systems and agro-ecological zones. The method and the approach described will enable collection of hard data within a reasonable time.     

Dinuclear N-heterocyclic carbene complexes of silver(I), derived from imidazolium-linked cyclophanes

The synthesis of four new silver complexes of bidentate N-heterocyclic carbenes, derived from imidazolium-linked cyclophanes, has been achieved via a simple complexation reaction of the imidazolium-linked cyclophanes with the basic metal source Ag(2)O. The cyclophane structures contain two imidazolyl links between ortho-, meta- and mixed ortho/meta-substituted aromatic rings. The new silver carbene systems are thermally stable and have been characterised by NMR spectroscopy and X-ray crystallography. Three of the complexes have a dimeric structure of the form [L(2)Ag(2)](2+) in the solid state that is rigid on the NMR timescale in solution. The fourth complex has a neutral structure of the form [L(AgBr)(2)], the NMR studies suggesting some lability of the L-Ag bonding in solution.     

Ultracold superstrings in atomic boson-fermion mixtures

We propose a setup with ultracold atomic gases that can be used to make a nonrelativistic superstring in four spacetime dimensions. In particular, we consider for the creation of the superstring a fermionic atomic gas that is trapped in the core of a vortex in a Bose-Einstein condensate. We explain the required tuning of experimental parameters to achieve supersymmetry between the fermionic atoms and the bosonic modes describing the oscillations in the vortex position. Furthermore, we discuss the experimental consequences of supersymmetry.     

Dynamical relativistic effects in photoionization: spin-orbit-resolved angular distributions of xenon 4d photoelectrons near the Cooper minimum

Two decades ago, it was predicted [Y. S. Kim et al., Phys. Rev. Lett. 46, 1326 (1981)] that relativistic effects should alter the dynamics of the photoionization process in the vicinity of Cooper minima. The present experimental and theoretical study of the angular distributions of Xe 4d(3/2) and 4d(5/2) photoelectrons demonstrates this effect for the first time. The results clearly imply that relativistic effects are likely to be important for intermediate- Z atoms at most energies.     

Tetrabutylammonium tribromide (TBATB) as an efficient generator of HBr for an efficient chemoselective reagent for acetalization of carbonyl compounds

Acyclic and cyclic acetals of various carbonyl compounds were obtained in excellent yields under a mild reaction condition in the presence of trialkyl orthoformate and a catalytic amount of tetrabutylammonium tribromide (TBATB) in absolute alcohol. Chemoselective acetalization of an aldehyde in the presence of ketone, unsymmetrical acetal formation, shorter reaction times, mild reaction conditions, the stability of acid-sensitive protecting groups, high efficiencies, facile isolation of the desired products, and the catalytic nature of the reagent make the present methodology a practical alternative.     

Theg factor of the lowest 7+ state in100Rh and 6− state in104Rh

Theg-factor of the 7⁺ state in¹⁰⁰Rh withT _1/2=140(5) ns and of the 6^? state in¹⁰⁴Rh withT _1/2=47(3)ns has been measured by the time-differential perturbedγ-ray angular distribution method (TDPAD). The obtained values are +0.67(2) and +0.33(1) respectively. The two nuclei were populated with reactions induced by⁷Li on^96,100Mo at a bombarding energy of 30 MeV. Shell model calculations using effective single particle moments show that the 7⁺ state in¹⁰⁰Rh has mostly a πg _9/2 ? vd _5/2 configuration, while the main component of the 6^? state in¹⁰⁴Rh is the πg _9/2 ? vh _11/2.