Ion beam figuring with focused anode layer thruster.

This work presents the peculiarities of cone ion beam formation with a focused thruster with anode layer (TAL) and its application to silicon carbide (SiC) ion beam figuring. Modeling results of Lorentz E × B force distribution in the discharge gap are presented. 3D particle tracing for keV Ar ions is carried out for the first time in the beam drift region of TAL with magnetic lens. Extracted ion beam full width at half maxima is about 2 mm in the focal plane, where the SiC etching rate reaches 0.5 µm/min. The SiC sputter yields are measured as a function of the Ar ion impact energy and beam incidence angle. The maximum sputter yield of 2.8 atom/ion is observed at 45° of the beam-sample angle for the Si targets. Furthermore, the maximum sputter yield value of 1.7 atom/ion is measured at 30° of the beam-sample angle for the SiC targets. The novelty of present research is in the application of focused TAL keV Ar ion beam to the SiC ion beam figuring.

Development status of the 18 GHz superconducting electron cyclotron resonance ion source at National Fusion Research Institute.

A new superconducting 18 GHz electron cyclotron resonance ion source is being developed at the National Fusion Research Institute in South Korea. This source will be dedicated for future application of highly charged ions in the area of matter interaction, diagnostic imaging, and probing. In this paper, we describe the status of the source development consisting of a double electrode biased disk, sputtering systems for metal ion production, diagnostic ports for the extraction region, a variable gap extraction-Einzel lens system, and a low energy beam transport system.

Inclined slot-excited annular electron cyclotron resonance plasma source for hyperthermal neutral beam generation.

An inclined slot-excited antenna (ISLAN) electron cyclotron resonance (ECR) plasma source is newly designed and constructed for higher flux hyperthermal neutral beam (HNB) generation. The developed ISLAN source is modified from vertical slot-excited antenna (VSLAN) source in two aspects: one is the use of inclined slots instead of vertical slots, and the other is a cusp magnetic field configuration rather than a toroidal configuration. Such modifications allow us to have more uniform arrangement of slots and magnets, then enabling plasma generation more uniform and thinner. Moreover, ECR plasma allows higher ionization rate, enabling plasma density higher even in submillitorr pressures, therefore decreasing the collision rate and∕or the reionization rate of the reflected atoms while passing through the plasma, and eventually getting higher flux of HNBs. In this paper, we report the design features and the plasma characteristics of the ISLAN source by doing plasma measurements and electromagnetic simulations. It was found that ISLAN source can be a high potential source for larger flux HNB generation; the source was found to give higher plasma densities and better uniformities than inductively coupled plasma source, particularly in low pressure ranges. Also, it is important that using ISLAN gives easier matching and better stability, i.e., ISLAN shows similar field patterns and good plasma symmetries irrespective of the variations of the mean diameter of the ring resonator and∕or the presence of a limiter or a reflector, and the operating pressures.

Combined effect of tumour necrosis factor-alpha and interleukin-13 polymorphisms on bronchial hyperresponsiveness in Korean children with asthma.

BACKGROUND: TNF-alpha and IL-13, two pivotal pro-inflammatory cytokines, are increased in asthmatic airways and may be linked to asthma susceptibility and/or bronchial hyperresponsiveness (BHR). OBJECTIVE: We investigated the association between the TNF-alpha-308G/A polymorphism and asthma susceptibility or asthma-related phenotypes in Korean children with asthma, and tested for a combined effect with IL-13 polymorphisms. METHODS: Asthmatic children (n=719) and non-atopic healthy control children (n=243) were evaluated for asthma phenotypes including total serum IgE and BHR to methacholine. Genotypes were determined by PCR-restriction fragment length polymorphism analysis. RESULTS: The allele frequency of TNF-alpha-308A in asthmatics (14.1%) was higher than that in control children [8.7%, odds ratio (OR) 1.72, 95% confidence interval (CI) 1.05-2.82]. Significantly lower PC(20) values were found in asthmatic children carrying one or two copies of the TNF-alpha risk allele (-308A) vs. those homozygous for the common allele (P=0.026). Combined analysis revealed that atopic asthmatic children co-inherited the risk alleles of TNF-alpha-308G/A and IL-13 +2044G/A more frequently than control children (aOR 1.91, 95% CI 1.00-3.65), and asthmatic children co-inheriting both risk alleles had significantly lower PC(20) values vs. asthmatic children homozygous for the common alleles (P=0.024). CONCLUSION: The TNF-alpha promoter polymorphism (-308G/A) may be associated with asthma susceptibility and BHR in Korean children with asthma. In addition, there appears to be a synergistic effect between the TNF-alpha promoter polymorphism and an IL-13 coding region polymorphism in terms of asthma susceptibility and BHR in this population.

TBXA2R gene polymorphism and responsiveness to leukotriene receptor antagonist in children with asthma.

BACKGROUND: Thromboxane A2 receptor (TBXA2R) gene polymorphism has been associated with atopy and asthma, but few studies have reported the effect of this gene polymorphism on asthma-related phenotype or responsiveness to leukotriene receptor antagonist (LTRA) in asthmatic children. This study investigated associations between asthma-related phenotypes and TBXA2R polymorphism, and also analysed whether the TBXA2R polymorphism has an effect on the efficacy of the LTRA, montelukast, in asthmatic children with exercise-induced bronchoconstriction (EIB). METHODS: Asthmatic children (n=695) and control children (n=159) were evaluated for asthma-related phenotypes including total IgE, pulmonary function test, and bronchial hyperresponsiveness to methacholine or exercise. Genotypes were detected by PCR-RFLP. In the montelukast study, exercise challenge was performed before and after an 8-week montelukast treatment. RESULTS: The TBXA2R polymorphism was not associated with asthma susceptibility and the clinical parameters of asthma. However, asthmatic children with combinations of the TBXA2R+795T>C and +924T>C risk alleles had significantly higher total IgE levels (P=0.01), total eosinophil counts (P<0.01) and lower forced expiratory volume in 1 s (FEV(1)) (P=0.02) and forced expiratory rates at 25-75% of vital capacity (P=0.02) than those carrying the common alleles. When compared with individuals with the common alleles, patients with the TBXA2R+924T>C TT homozygote and TBXA2R+795T>C hetero- or homozygote (CT or CC) had a 3.67-fold poor response to 8-week montelukast treatment with respect to maximum percent fall in FEV(1) after exercise (odds ratio, 3.67; 95% confidence interval, 1.15-11.15). CONCLUSIONS: A combined effect of TBXA2R+795T>C and +924T>C risk alleles may be linked to IgE production, eosinophilic inflammation, and severity of asthma. In addition, the TBXA2R+795T>C genotype may be a predictive marker of a clinical response to the LTRA in Korean asthmatic children with EIB.

Responsiveness to montelukast is associated with bronchial hyperresponsiveness and total immunoglobulin E but not polymorphisms in the leukotriene C4 synthase and cysteinyl leukotriene receptor 1 genes in Korean children with exercise-induced asthma (EIA).

BACKGROUND: As previous studies have shown that cysteinyl leukotrienes are important mediators in exercise-induced bronchoconstriction (EIB), and leukotriene receptor antagonists (LTRAs) such as montelukast have been shown to improve post-exercise bronchoconstrictor responses, we herein investigated whether clinical responsiveness to montelukast was associated with polymorphisms in the genes encoding leukotriene C4 synthase (LTC4S) and cysteinyl leukotriene receptor 1 (CysLTR1) and/or clinical parameters in Korean asthmatic children with EIB. METHODS: The study population consisted of 100 asthmatic children with EIB. The individuals studied were given exercise challenge tests before and after receiving montelukast (5 mg/day) for 8 weeks. Responders were defined as children showing>10% post-treatment improvement in forced expiratory volume in 1 s (FEV1). The LTC4S A(-444)C and CysLTR1 T(+927)C polymorphisms were genotyped by PCR-restriction fragment length polymorphism analysis. RESULTS: Of 100 enrolled children, 68 were classified as responders and 32 were classified as non-responders. No significant association was observed between montelukast responsiveness and LTC4S or CysLTR1 genotype, either alone or in combination. In contrast, montelukast-induced improvement in FEV(1) after exercise was correlated with higher pre-treatment PC20 (methacholine) values (r=0.210, P=0.036) and lower total IgE levels (r=-0.216, P=0.031). CONCLUSIONS: The LTC4S A(-444)C and CysLTR1 T(+927)C genotypes do not appear to be useful for predicting clinical responsiveness to montelukast, whereas bronchial hyperresponsiveness and total IgE appear to predict the degree of montelukast responsiveness in Korean asthmatic children with EIB.