Spectroscopy of the hyperfine structure of antiprotonic 4He and 3He

The spin magnetic moment $\mu^{\overline{p}}_{s}$ of the antiproton can be determined by comparing the measured transition frequencies in $\overline{p}^4$ He^?+? with three-body QED calculations. A comparison between the proton and antiproton can then be used as a test of CPT invariance. The highest measurement precision of the difference between the proton and the antiproton spin magnetic moments to date is 0.3%. A new experimental value of the spin magnetic moment of the antiproton was obtained as $\mu^{\overline{p}}_{s} = -2.7862(83)\mu_{N}$ , slightly better than the previously best measurement. This agrees with $\mu^{p}_{s}$ within 0.24%. In 2009, a new measurement with antiprotonic ³He has been started. A comparison between the theoretical calculations and experimental results would lead to a stronger test of the theory and address systematic errors therein. A measurement of this state will be the first HF measurement on $\overline{p}^3$ He^?+?. We report here on the new experimental setup and the first tests.     

Magnetic and electrical properties of bulk BaTiO3+MgFe2O4 composite

BaTiO₃+MgFe₂O₄ material system was synthesized by hybrid chemical process using chlorides and nitrates of barium, titanium, iron, and magnesium. Magnetic properties of the composite samples measured as a function of annealing conditions indicated soft magnetic behavior. Saturation specific magnetization from 8 21 emu/g was observed for samples annealed at temperature between 950 and 1150 °C. Variation of specific saturation magnetization with respect to annealing temperature was related with the distribution of Fe cations in the tetrahedral and octahedral sites of MgFe₂O₄. Electrical properties of the samples annealed at different temperatures were measured to analyze the coexistence of ferroelectric phase. Dielectric constant varying from 15 to 200 with respect to frequency was observed for samples annealed from 950 to 1150 °C.     

Nondestructive evaluation for remanent life of modified 9Cr-1Mo steel by reversible magnetic permeability

We present a magnetic and nondestructive method to evaluate the remanent life of modified 9Cr-1Mo steel by measuring the reversible magnetic permeability. Specimens with ten different kinds of aging periods were prepared using an isothermal heat treatment at 690 °C. The Larson-Miller parameter (LMP) was calculated and the peak interval of reversible magnetic permeability (PIRMP) was measured using the surface type probe. PIRMP was inversely proportional to LMP. We can evaluate the remanent life of modified 9Cr-1Mo steel using the relationship between PIRMP and LMP. Also, we present the possibility that the tensile strength and yield strength measured by destructive methods could be estimated by PIRMP measured nondestructively.     

HGLM modelling of dropout process using a frailty model

Summary  We introduce a shared random-effect model, derived from frailty models to account for informative dropout. We extend the iterative weighted least squares algorithm for hierarchical generalized linear models to shared random-effect models. Monte-Carlo simulations are carried out to illustrate that the proposed method works well whether the random-effect distribution is correctly specified or not. This study was supported by a grant of the Korea Health 21 R & D Project, Ministry of Health & Welfare, Republic of Korea. (01-PJ1-PG3-51200-0002).     

Influences of organometallic polymer‐derived catalyst dispersion on SWNT growth

Catalyst formation kinetics of a ferrocene‐containing homopolymer, polyferrocenylethylmethylsilane (PFEMS), is investigated as it relates to the catalysis of single walled carbon nanotubes (SWNTs) through a chemical vapor deposition (CVD) process. The formation and efficiency of the PFEMS‐based iron catalyst is compared with that of the corresponding polystyrene (PS)‐b‐PFEMS diblock copolymer. The PFEMS homopolymer contains 23 wt % iron, while PS‐b‐PFEMS, with a 25 vol % PFEMS content, is only 6% iron. Despite its lower iron content, spin‐cast PS‐b‐PFEMS films on SiO₂/Si substrates produce more active iron sites than spin‐cast PFEMS films during CVD growth of SWNTs. This is related to the self‐assembly of the block copolymer, where PFEMS domains are well dispersed in the PS matrix, which degrades at a CVD temperature of 920 °C to leave catalytically active elemental iron behind. On the contrary, the pure PFEMS films contain a high percentage of iron and silicon, which tend to transform into ceramic‐coated iron at this high temperature, thus rendering the iron inactive towards SWNT growth. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 758–765, 2007     

The preparation of nanophase tungsten carbide powder with zeolite-X catalysts

The reduction–carburization of tungsten trioxide (WO₃) under carbon monoxide flow was studied in the temperature range of 300–750 °C. The reduction–carburization of WO₃ was improved by mechanically mixing with zeolite-HX, -NaX and -KX. The interaction between cation in zeolite-X and oxygen in WO₃ affected the improvement of the reduction–carburization of WO₃ to WC. Moreover, the improved reduction–carburization of WO₃ could lead to the decrease of reaction temperature. Because the particle size of WC is in contact with a reaction temperature, the nanophase WC can be prepared at low temperature. In particular, the particle size of WC was controlled by reaction temperature. The particle sizes of produced WC at 550, 650 and 700 °C were 25, 50 and 100 nm respectively.     

Advantages of Adaptive Speckle Filtering Prior to Application of Iterative Deconvolution Methods for Optical Coherent Tomography Imaging

The axial resolution of optical coherence tomography (OCT) is closely related to the light source spectrum width. Unfortunately, most basic sources providing the required power for decent OCT image have narrow spectra, which generate a resolution loss. Assuming the OCT system is linear shift-invariant, we can consider the system output as the convolution of the theoretical signal with a system impulse response due to this spectrum narrowness. It becomes then possible to enhance this resolution through iterative deconvolution methods (IDM). However those methods have a significant drawback, as they usually significantly enhance speckle, which is another consequence of the source spectrum narrowness. To compensate this, we rely on preliminary speckle filtering, and especially the adaptative ones, which allow tackling the speckle without blurring the image. We first studied enhancement proposed by most popular IDMs on OCT images, and then the effect of preliminary adaptive speckle filtering (ASF) by different common adaptive methods. Then, among those methods, we combined Frost filter and Richardson-Lucy deconvolution in the appropriated way; this way we both enhanced resolution by 2 and reduced speckle (raising CNR from 0.7 to 1.3)     

The enhanced expression of IL-17-secreting T cells during the early progression of atherosclerosis in ApoE-deficient mice fed on a western-type diet

Atherosclerosis is a chronic progressive inflammatory disorder and the leading cause of cardiovascular mortality. Here we assessed the dynamic changes of T-cell-derived cytokines, such as inteferon (IFN)-γ, interleukin (IL)-17 and IL-4, during the progression of atherosclerosis in apolipoprotein E-null (ApoE^−/−) mice, to understand the role of immune responses in different stages of atherosclerosis. Male ApoE^−/− mice were fed a high-fat, western-type diet (WD: 21% lipid, 1.5% cholesterol) after 5 weeks of age and were compared with C57BL/6 wild-type control mice fed a standard chow diet. Atherosclerotic lesions appeared in the aortic sinus of ApoE^−/− mice 4 weeks after WD and the lesions progressed and occupied >50% of the total sinus area 16 weeks after WD. Aortic IL-17 mRNA and protein expression started to increase in ApoE^−/− mice after 4 weeks on the WD and peaked at around 8–12 weeks on the WD. In terms of systemic expression of T-cell-derived cytokines, IL-17 production from splenocytes after anti-CD3/CD28 stimuli increased from 4 weeks on the WD, peaked at 12 weeks and returned to control levels at 16 weeks. The production of IFN-γ and IL-4 (Th1 and Th2 cytokines, respectively) from splenocytes was delayed compared with IL-17. Taken together, the present data indicate that Th17 cell response may be involved at an early stage in the development of atherosclerosis.