Effect of geometry on magnetization distortion in closed-circuit magnetic measurements

The effect of specimen geometry on magnetization distortion in closed-circuit measurements is reported in this letter. The degree of the distortion increases as the ratio of length to diameter (L/D) of specimen decreases, and the distortion can reduce the magnetization values as much as 42% when the applied magnetic field is 24 kOe and the L/D is 0.28. The type of magnetic material also affects the distortion. Although the phenomenon seems to be similar to the “image effect” that occurs in open-circuit measurements, reports of this effect in closed-circuit measurements have not been found in the literature. Further research effort, including 3D computer modeling, for understanding this magnetic phenomenon is underway and will be reported later.     

Model two-dimensional diffraction profiles from disordered vicinal surfaces and random island configurations

Methods for calculating model diffraction profiles of vicinal surfaces and distributions of islands are described. Modeling of rough terrace edges, and of island structures on terraces, has been performed using phenomenological Hamiltonians. The methods are developed for calculating diffraction profiles in all components, s_x, s_z, and s_y, of the momentum transfer. It is s of step structure irregularities is related to profile shape. Qualitative comparison with experiment is made based on the observed characteristics of terraces obtained from STM and LEED data of vicinal Si(OO1).     

Embedding Structures

 For any quasiordered set (`quoset') or topological space S, the set Sub S of all nonempty subquosets or subspaces is quasiordered by embeddability. Given any cardinal number n, denote by p _n and q _n the smallest size of spaces S such that each poset, respectively, quoset with n points is embeddable in Sub S. For finite n, we prove the inequalities n + 1 ≤p _n ≤q _n ≤p _n + l(n) + l(l(n)), where l(n) = min{k∈ℕ∣n≤2 ^k }. For the smallest size b _n of spaces S so that Sub S contains a principal filter isomorphic to the power set ?(n), we show n + l(n) − 1 ≤b _n ≤n + l(n) + l(l(n))+2. Since p _n ≤b _n , we thus improve recent results of McCluskey and McMaster who obtained p _n ≤n ². For infinite n, we obtain the equation b _n = p _n = q _n = n. Received: April 19, 1999 Final version received: February 21, 2000     

Recent Progress with the SMILETRAP Penning Mass Spectrometer

The Penning trap mass spectrometer SMILETRAP has been considerably improved during the last two years. The helium pressure has been carefully stabilized and is now independent of irregular air pressure. The temperature of the hyperboloidal precision trap is stabilized to ±0.03°C. Remaining temperature instabilities are compensated by changes in the current of a warm coil surrounding the precision trap. The frequency synthesizer is now locked to GPS. This means that it is much easier to accurately measure resonances during several days. The improvements have demonstrated that in mass doublet measurements with an excitation time of 1 s it is possible to determine the mass of ions with q/A=1/2 at an uncertainty to a few times of 0.1 ppb, using selected rather than cooled ions. In routine measurements lasting for one day it is possible to reach a mass uncertainty of 1 ppb. The masses of the following particles and atoms have been measured with uncertainties in the region 0.3–2 ppb: p, ³H, ³He, ⁴He, ²²Ne, ²⁸Si, ³⁶Ar, ⁷⁶Ge, ⁷⁶Se, ⁸⁶Kr and ¹³³Cs. It has also been shown that though we are using a warm bore the trap pressure is sufficiently low to prevent electron capture from the rest gas for excitation times of 3 s and for ion charges as high as 50+. This revised version was published online in July 2006 with corrections to the Cover Date.     

Structural studies on banana oil,isoamyl acetate,by means of microwave spectroscopy and quantum chemical calculations

The rotational spectrum of isoamyl acetate, H₃C–COO–(CH₂)₂–CH(CH₃)₂, has been recorded and assigned using a molecular beam Fourier transform microwave (MB-FTMW) spectrometer in the frequency range of 3–26.5?GHz. One conformer has been observed. By comparing the spectroscopic data with the quantum chemical data, it was found that the conformer observed does not have C_s symmetry. The rotational and centrifugal distortion constants were determined. The barrier to internal rotation of the acetate methyl group was found to be 93.98?cm^?1. Due to the high number of the conformers, a systematic nomenclature will be presented.     

Nachweis von Peroxyden und Persalzen

Ohne Zusammenfassung