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A promising accelerator light source mechanism called steady-state microbunching (SSMB) is being actively studied. With the combination of strong coherent radiation from microbunching and high repetition rate of a storage ring, high-average-power narrow-band radiation can be anticipated from an SSMB storage ring, with wavelengths ranging from THz to soft X-ray. Such a novel light source could provide new opportunities for accelerator photon science like high-resolution angle-resolved photoemission spectroscopy and industrial applications like extreme ultraviolet (EUV) lithography. In this paper, a theoretical and numerical study of the average and statistical properties of coherent radiation from SSMB are presented. The results show that 1 kW average-power quasi-continuous-wave EUV radiation can be obtained from an SSMB ring provided that an average current of 1 A and a microbunch train with bunch length of 3 nm can be formed at the radiator which is assumed to be an undulator. Together with the narrow-band feature, the EUV photon flux can reach 6 × 1015 photons s-1 within a 0.1 meV energy bandwidth, which is three orders of magnitude higher than that in a conventional synchrotron source and is appealing for fundamental condensed matter physics and other research. In this theoretical investigation, we have generalized the definition and derivation of the transverse form factor of an electron beam which can quantify the impact of its transverse size on coherent radiation. In particular, it has been shown that the narrow-band feature of SSMB radiation is strongly correlated with the finite transverse electron beam size. Considering the pointlike nature of electrons and quantum nature of radiation, the coherent radiation fluctuates from microbunch to microbunch, or for a single microbunch from turn to turn. Some important results concerning the statistical properties of SSMB radiation are presented, with a brief discussion on its potential applications, for example the beam diagnostics. The presented work is of value for the development of SSMB to better serve potential synchrotron radiation users. In addition, this also sheds light on understanding the radiation characteristics of free-electron lasers, coherent harmonic generation, etc. [ABSTRACT FROM AUTHOR]

Ferrite powder samples of Mn xNi1- xFe2O4 (0.0 ≤ x ≤ 1.0) with single phase (A)[B]2O4 spinel structure were prepared using a sol-gel method. Following the successful proposal by our group, that the magnetic moment directions of Cr2+ (3d4) cations are antiparallel to those of Fe3+ (3d5) and Fe2+ (3d6) cations in a given sublattice of the Cr-doped spinel ferrites due to the constraints imposed by Hund's rules, we extend here the same idea and assume that the magnetic moment directions of Mn3+ (3d4) cations are also antiparallel to those of Mn2+ (3d5) and divalent and trivalent Fe (Ni) cations in a given sublattice of Mn-doped spinel ferrites. We have thereby obtained cation distributions for the samples by fitting the magnetic moments of the samples at 10 K. The results indicate that 72% of the Mn cations occupy the [B] sites in MnFe2O4, which is close to the results for Ni (82%) in NiFe2O4, but is different from the result obtained using the conventional view which yields 80% of the Mn cations in the (A) sites of MnFe2O4. On the basis of the present analyses of the magnetic structure of Mn xNi1- xFe2O4 (0.0 ≤ x ≤ 1.0), we propose here a new model for spinel ferrites that is distinctly different from both the super- and the double-exchange model and that we refer to as the O2p itinerant electron model. Using this model, not only can the magnetic structure of the spinel ferrites MFe2O4 ( M = Fe, Co, Ni, and Cu) be explained better than by using the super- and double-exchange interaction models, but also the magnetic structure and the cation distributions of Cr-, Mn-, and Ti-doped spinel ferrites can be explained. [ABSTRACT FROM AUTHOR]

Ti-doped Ni0.68Fe2.32O4 spinel ferrite samples with nominal composition Ni0.68−0.8 xTi xFe2.32−0.2 xO4 (0 ≤ x ≤ 0.312) were prepared using conventional ceramic methods. The samples exhibited a single-phase cubic spinel structure. When the doping level had values x > 0.15, a transition temperature, TN, was found, below which the magnetization of the samples decreased with decreasing measurement temperature. This phenomenon indicates that an additional antiferromagnetic structure arises in the traditional spinel phase of ferrites resulted from Ti doping. Therefore, Ti ions appear in the form of Ti3+ and Ti2+ cations that have magnetic moments, rather than as Ti4+ cations without magnetic moment as assumed by many researchers. The dependence of the magnetic moments on the Ti doping level x at 10 K was fitted successfully using our quantum-mechanical potential barrier model proposed earlier. In the fitting process, we assumed that the magnetic moments of the Ti cations were opposite to the direction of the Fe and Ni moments. According to the fitted results, the Ti2+ cations at the [B] sites constitute about 81% of the total Ti content x for all samples, which is close to the content of the Ni2+ cations at the [B] sites (77%). [ABSTRACT FROM AUTHOR]

Between March and August 1986 in Huangshi City, serum samples were collected from 316 apparently healthy barbers as a study group, as well as from 361 healthy employees of department stores as a control group. They were tested for hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs) and antibody to hepatitis B core antigen (anti-HBc) by enzyme-linked immunoadsorbent assays. Barbers showed a prevalence higher than that in controls for HBsAg (16.8 vs. 9.2%, P less than 0.01), anti-HBs (67.1 vs. 45.9%, P less than 0.001), and anti-HBc (39.2 vs. 21.2%, P less than 0.001). The prevalence of at least one marker of hepatitis B virus (HBV) infection was significantly higher in barbers than in controls (86.1 vs. 61.7%, P less than 0.001). Although the socioeconomic status and education level did not correlate with the frequency of HBV markers, the prevalence of HBsAg increased in parallel with the duration of practice. Because of their high risk for HBV infection, barbers need to be screened for markers of HBV infection on a routine basis, and are prime candidates for immunoprophylaxis with hepatitis B vaccine.