Rapid measurement of the deformation of the liner in a superconducting wiggler when the magnets transition to the normal state

The liner of a superconducting wiggler is a thin-walled elliptical copper tube that is positioned inside the vacuum chamber and serves as a heat shield. When the wiggler magnets transition to the normal state, the liner is affected by vertical forces that are able to deform it. In this work, a system for the rapid measurement of the deformation of a liner is described and the measurement results for three different liners are reported.     

Dynamic surface properties of sodium N-acryloyl-11-amimoundecanoate and poly(sodium N-acryloyl-11-aminoundecanoate)

Adsorption layers of sodium N-acryloyl-11-amimoundecanoate and poly(sodium N-acryloyl-11-aminoundecanoate) (PAAU-Na) are studied using surface dilatational rheology measurements. It is established that the dynamic surface elasticity values of the studied systems are different, while their surface tension isotherms are almost the same. PAAU-Na solutions containing excess indifferent electrolyte (NaCl) exhibit a conformational transition in a surface layer due to the formation of loops and tails, which penetrate the bulk phase. Slow variations in the surface properties of PAAU-Na solutions with time seem to be caused by the aggregation of macromolecules in the bulk phase. The aggregation process is investigated by scanning probe microscopy.     

Quantification of homonuclear dipolar coupling networks from magic-angle spinning 1H NMR

Numerical simulations of magic-angle spinning (MAS) spectra of dipolar-coupled nuclear spins have been used to assess different approaches to the quantification of dipolar couplings from ¹H solid-state NMR. Exploiting the translational symmetry of periodic spin systems allows extended networks with ‘realistic’ numbers of spins to be considered. The experimentally accessible parameter is shown to be the root-sum-square of the dipolar couplings to a given spin. The effectiveness of either fitting the resulting spinning sideband spectra to small spin system models, or using analyses based on moment expansions, has been examined. Fitting of the spinning sideband pattern is found to be considerably more robust with respect to experimental noise than frequency domain moment analysis. The influence of the MAS rate and system geometry on robustness of the quantification is analysed and discussed.     

Single-charge transistor based on the charge-phase duality of a superconducting nanowire circuit

We propose a transistorlike circuit including two serially connected segments of a narrow superconducting nanowire joint by a wider segment with a capacitively coupled gate in between. This circuit is made of amorphous NbSi film and embedded in a network of on-chip Cr microresistors ensuring a sufficiently high external electromagnetic impedance. Assuming a virtual regime of quantum phase slips (QPS) in two narrow segments of the wire, leading to quantum interference of voltages on these segments, this circuit is dual to the dc SQUID. Our samples demonstrated appreciable Coulomb blockade voltage (analog of critical current of the SQUIDs) and periodic modulation of this blockade by an electrostatic gate (analog of flux modulation in the SQUIDs). The model of this QPS transistor is discussed.     

Refined comparison theorems for the Dirac equation in d dimensions

A single spin‐1/2 particle obeys the Dirac equation in spatial dimension and is bound by an attractive central monotone potential which vanishes at infinity (in one dimension the potential is even). This work refines the relativistic comparison theorems which were derived by Hall 1 . The new theorems allow the graphs of the two comparison potentials and to crossover in a controlled way and still imply the spectral ordering for the eigenvalues at the bottom of each angular momentum subspace. More specifically in a simplest case we have: in dimension , if , then ; and in dimensions, if , where and , then .

     

Synthesis of Analogs of Juvenile Hormons Proceeding from Phenol Derivatives

New potential juvenoids, esters of alkenoic and alkadienoic acids with phenoxy- and phenoxyphenoxyethanol were synthesized, and also esters of phenoxyacetic acid with alkenols amd alkadienols.     

Insect Pheromones and Their Analogs. LXI. Synthesis of 4E,10Z-Tetradecadien-1-ylacetate, a Component of the Lithocolettis ringoniella Sex Pheromone

A new scheme for synthesizing 4E,10Z-tetradecadien-1-ylacetate, the principal component of the apple leaf miner(Lithocolettis ringoniella)sex pheromone, is developed using a highly stereoselective Claisen rearrangement     

Homolytic alkylation of oxine (8-hydroxyquinoline) with 1,4-dioxane

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, p. 1143, August, 1988.