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Real-time detection of an airborne microorganism using inertial impaction and mini-fluorescent microscopy

2024-04-25T09:38:04Z

Title: Real-time detection of an airborne microorganism using inertial impaction and mini-fluorescent microscopy Authors: Kang, Joon Sang; Lee, Kang Soo; Kim, Sang Soo; Bae, Gwi-Nam; Jung, Jae Hee Abstract: To achieve successful real-time detection of airborne pathogenic microorganisms, the problem must be considered in terms of their physical size and biological characteristics. We developed an airborne microorganism detection chip to realize the detection of microorganisms, ensuring compactness, sensitivity, cost-efficiency, and portability, using three key components: an inertial impaction system, a cartridge-type impaction plate, and a mini-fluorescent microscope. The inertial impaction system was used to separate microorganisms in terms of their aerodynamic particle size, and was fabricated with three impaction stages. Numerical analysis was performed to design the system; the calculated cutoff diameter at each impaction stage was 2.02 (first stage), 0.88 (second stage), and 0.54 mu m (third stage). The measured cutoff diameters were 2.24, 0.91, and 0.49 mu m, respectively. A cartridge-type impaction plate was used, composed of molded polydimethylsiloxane (PDMS) and an actual impaction region made of a SYBR green I dye-stained agar plate. A mini-fluorescent microscope was used to distinguish microbes from non-biological particles. Images of the microorganisms deposited at the impaction zone were obtained via mini-fluorescent microscopy, and fluorescent intensities of the images were calculated using in-house image-processing software. The results showed that the developed system successfully identified aerosolized biological particles from non-biological particles in real time.

Secure U-healthcare service based on wireless sensor network

2024-04-25T09:37:56Z

Title: Secure U-healthcare service based on wireless sensor network Authors: Park, J.-M.; Doh, I.; Chae, K. Abstract: In ubiquitous healthcare service, it is especially important to protect the security, because sensitive data directly related to patients' health and their lives are transmitted via a public network. In this paper, we propose a security system architecture which provides user authentication and several modules for secure data processing scheme using mobile phones. We also consider the situated environment and parameters for classifying patients' data and rekeying for security enhancement. ？ 2014 International Information Institute.

Cytochrome P450-mediated metabolic alterations in preeclampsia evaluated by quantitative steroid signatures

2024-04-25T09:37:54Z

Title: Cytochrome P450-mediated metabolic alterations in preeclampsia evaluated by quantitative steroid signatures Authors: Moon, Ju-Yeon; Moon, Myeong Hee; Kim, Ki Tae; Jeong, Dae Hoon; Kim, Young Nam; Chung, Bong Chul; Choi, Man Ho Abstract: Although preeclampsia has been suggested potential risk factors including placental and systemic inflammation, oxidative stress, and abnormal steroid metabolism during pregnancy, the pathogenesis of preeclampsia has not fully been elucidated, particularly in steroid metabolism. The association between various cytochrome P450 (CYP)-mediated steroid metabolic markers and preeclampsia risk was therefore investigated. The serum levels of 54 CYP-mediated regioselective hydroxysteroids and their substrates were quantitatively evaluated from both pregnant women with preeclampsia (n = 30; age, 30.8 +/- 4.5 years) and normotensive controls (n = 30; age, 31.0 +/- 3.5 years), who were similar with respect to maternal age, gestational age, and body mass index. The levels of 6 beta-, 7 alpha-, and 11 beta-hydroxymetabolites of androgens and corticoids were significantly increased in women with preeclampsia. In addition, the levels of oxysterols, including 7 alpha-, 7 beta-, 4 beta-, 20 alpha-, 24S-, and 27-hydroxycholesterol, were markedly higher, while the levels of 16 alpha-OH-DIEA, 16 alpha-OH-androstenedione, and cholesterol were significantly decreased in patients. The 6 beta-hydroxylation of androgens and corticoids by CYP3A4 (P < 0.01), the activation of 20,22-desmolase (a cholesterol side-chain cleavage enzyme) by CYP11A1 (P < 0.00001), and the multi-hydroxylation of cholesterol at C-4 beta, C-7 alpha, C-7 beta, C-24S, C-27, and C-20 alpha (P < 0.0001) by catalytic or enzymatic reaction (e.g. CYP3A4, CYP7A1, CYP27A1, and CYP46A1) were differed between preeclamptic women and control subjects. In particular, an increased oxysterols (induction > 2.0-fold) were positively correlated with the conditions of preeclampsia. Our metabolic profiling suggests the CYP-mediated alterations in steroid metabolism and hydroxylation in pregnancy-induced hypertension. These multiple markers could serve as background information for improved clinical diagnosis and management during pregnancy. This article is part of a Special Issue entitled "Pregnancy and Steroids". (C) 2013 Elsevier Ltd. All rights reserved.

Numerical investigation of a hybrid-connection four-junction solar cell structure based on detailed balance calculation

2024-04-25T09:37:52Z

Title: Numerical investigation of a hybrid-connection four-junction solar cell structure based on detailed balance calculation Authors: Ahn, Youngkun; Kim, Young-Hwan; Choi, Won-Jun; Kim, Seong-Il Abstract: On the basis of the detailed balance limit model, we calculated limiting efficiency, optimum bandgap energy combination, current density-voltage (J-V) characteristics, and theoretical efficiency for the candidate combination of materials GaInN/GaInP/Ga(In) As/Ge and the thermalization loss of a hybrid-connection four-junction (HC4J) solar cell structure to investigate its theoretical characteristics. Instead of the three-tunnel junctions and series-connection between subcells in a conventional four-junction solar cell, HC4J has two tunnel junctions only, with one junction having been replaced by a transparent electrode. The transparent electrode connects the topmost subcells with the top subcell. The theoretical optimum bandgap combination and the limiting efficiency of HC4J are 3.19/1.77/1.19/0.70 eV and 52.1 %, respectively. To assess the feasibility of the structure, theoretical J-V characteristics were evaluated for GaInN/GaInP/Ga(In) As/Ge with associated bandgap energies 3.20/1.87/1.22/0.7 eV. The open-circuit voltage and short-circuit current were 2.87 V and 17.18 mA/cm(2), respectively. Thermalization loss was also calculated for the candidate materials.