Preparation of high-quality YAG:Ce3+ ceramic phosphor by high-frequency induction heated press sintering methods.

This study investigates the characteristics of a ceramic phosphor (CP) for the converter of a high-power laser diode-based automobile headlamp synthesized by high-frequency induction heated press (HFP) sintering. The CP prepared by an HFP method exhibits remarkable optical properties that are comparable to spark plasma sintering. The effects of post-treatment process for controlling residual pores, as well as sintering temperature, sintering pressure and heating rate for optimization of the HFP sintering method, were studied. The HFP sintering process can be widely used in ceramics and lighting fields because it is designed relatively low cost compared to other techniques and exhibits excellent productivity.

Bredigite-structure orthosilicate phosphor as a green component for white LED: the structural and optical properties.

A green-emitting phosphor, Ca14-xEuxMg2[SiO4]8 (CMS:Eu²âº), has been synthesized as a component of white light emitting diodes (WLEDs). The emission spectrum is broad, with a maximum at about 505 nm under 400 nm excitation due to the transition from the 4f65d excited state to the 4f7-ground state of a Eu²âº ion. The dipole-dipole interaction was a dominant energy transfer mechanism of the electric multipolar character of CMS:Eu²âº. The critical distance was calculated as 12.9 Å and 14.9 Å using a critical concentration of Eu²âº and Dexter's theory for energy transfer. When CMS:Eu²âº and red phosphor are incorporated with an encapsulant on an ultraviolet (λmax = 395 nm) light emitting diodes (LEDs), white light with a color rendering index of 91 under a forward bias current of 20 mA was obtained. The structural and optical characterization of the phosphor is described.

A comparison between impulse oscillometry system and spirometry for spirometry for detecting airway obstruction in children / 소아과

PURPOSE: Measurement of forced expiratory volume in 1 second (FEV1) is usually difficult to obtain in children under six years of age because it requires active cooperation. This study evaluates the sensitivity of impulse oscillometry system (IOS) parameters for detecting airway obstruction in comparison with FEV1. METHODS: We studied 174 children who performed the lung function and methacholine challenge tests to diagnose asthma by IOS and spirometry. Children were divided into two subgroups according to their PC20, which is a parameter for bronchial sensitivity. We compared IOS parameters with FEV1 at the baseline, post-methacholine challenge, and evaluated their correlation. RESULTS: At the baseline, reactance at 5 Hz (X5) and resistance at 5 Hz (R5) significantly differed between the PC20 positive (PC2016 mg/mL) group; however, FEV1, FEV1% predicted, FEV1_Zs (Z score) did not differ. FEV1 is correlated with X5 (r=0.45, P<0.01) and R5 (r=-0.69, P<0.01). FEV1_Zs is also correlated with X5_Zs (r=-0.26, P<0.01) and R5_Zs (r=-0.31, P<0.01). After the methacholine challenge test, dose-response slopes in FEV1 and X5 significantly differed between the two subgroups (P<0.05). CONCLUSION: IOS parameters were more discriminative than FEV1 for detecting decreased baseline lung function between two subgroups and have a good correlation with FEV1.

Reference values for respiratory system impedance using impulse oscillometry in school-aged children in Korea / 소아과

PURPOSE: The impulse oscillometry (IOS) is applicable to young children because it requires minimal cooperation and a non-invasive method to measure the mechanics of respiratory system. This study aimed to develop the reference values in school-aged children in Korea, using IOS which is a modification of forced oscillation technique (FOT). METHODS: Measurements were performed in 92 previously untrained healthy children, aged 7 to 12 years old, using IOS. We analyzed the relationships between the data about their age, height, weight, body surface area (BSA), body mass index (BMI) and the result of IOS using the linear regression test. RESULTS: The success rate of IOS was 92.4%. Stepwise multiple regression of resistance of respiratory system (Rrs) and reactance of respiratory system (Xrs) in natural form for age, height, weight, BSA, BMI showed that height was the most significant predictor and altogether of 5 variables explained the Rrs and Xrs most. Our regression equations at multiple frequencys were comparable to published reference values, especially about the Rrs obtained at 5 Hz. CONCLUSION: IOS is a feasible method to measure the respiratory resistance in untrained children. We got the reference values using IOS and it seems to be useful to diagnose a variety of respiratory diseases.

Increased Serum Thymus and Activation-regulated Chemokine (TARC) Levels in Children with Atopic Dermatitis / 소아알레르기및호흡기학회지

PURPOSE: Thymus and activation-regulated chemokine (TARC) is responsible for the trafficking of Th2 lymphocytes into sites of allergic inflammation. We tested whether TARC is a useful marker for childhood atopic dermatitis (AD) and we evaluated age-related differences in the level of TARC. METHODS: Serum TARC level, serum total IgE level, total eosinophil count and specific IgE level were measured in 401 children. They were characterized as having IgE-mediated atopic dermatitis (n=157), non-IgE mediated atopic dermatitis (n=107), or as healthy control subjects (n=137). RESULTS: TARC levels in AD significantly were higher than those in healthy control subjects. (152.9+/-11.6 vs 56.7+/-5.2 pg/mL, P< 0.05) Serum TARC levels significantly correlated with disease severity (SCORAD index) both in children with IgE mediated AD (r=0.670, P< 0.05) and children with non-IgE mediated AD. (r=0.605, P< 0.05) Serum TARC levels in control subjects decreased in accordance with age. (r=-0.201, P< 0.05) CONCLUSION: Serum TARC might be a useful marker for disease severity both in children with IgE mediated AD and children with non-IgE mediated AD. Serum TARC levels in control subjects decreased in accordance with ages.