Ultrasensitive ratiometric photoelectrochemical immunoassay for prostate specific antigen based on nanoscale heterojunction
SENSORS AND ACTUATORS B-CHEMICAL
Authors: Lu, Yan; Zhang, Bin; Tian, Ya; Guo, Qingfu; Nie, Guangming
Abstract
A new photoelectrochemical (PEC) immunosensor is fabricated for the ultrasensitive detection of prostatespecific antigen (PSA). Nanoscale poly(indole-5-carboxylic acid) (P5ICA)/WO3 p-n type heterojunction is firstly used as the photoactive material with good photoelectric activity and chemical stability. The energy level matching effect between P5ICA and WO3 is conducive to the generation of stronger photocurrent signals. The sensitization effect of this heterojunction can also increase the absorption range of visible light and improve the utilization of light. This ratiometric device includes detection section (DS) and reference section (RS), which are equipped on a single FTO electrode. DS incubates with different concentrations of PSA, and RS incubates with a constant concentration of PSA. Thus, the ultrasensitive ratiometric detection of PSA is achieved by the ratio value of photocurrents (DS/RS), reducing the impact of external factors on detection results effectively. This sensor exhibits a dynamic working range between 0.0005-50 ng mL(-1) with a limit of detection (LOD) of 0.00012 ng mL(-1) and a limit of quantification (LOQ) of 0.0004 ng mL(-1). In addition, this sensor has high selectivity, good portability and acceptable detection accuracy in actual samples, which indicates potential applications for detection of disease-related biomarkers.
A development of methodology for assessing the inter-unit common cause failure in multi-unit PSA model
RELIABILITY ENGINEERING & SYSTEM SAFETY
Authors: Jang, Seunghyun; Jae, Moosung
Abstract
The inter-unit common cause failure (CCF) is an event that multiple components are failed simultaneously by common factors may existent in nuclear power plants on a site. The inter-unit CCF can be identified as one of the inter-unit dependencies that has an impact on the multi-unit probabilistic safety assessment (MUPSA). For instance, it may adversely affect the accident mitigation in accident scenarios of multiple units. Therefore, the MUPSA model should be developed considering the inter-unit CCF. In this study, we proposed two methods with the Swain's dependency model and the CCF data in the single-unit PSA (SUPSA) to calculate the inter-unit CCF. The Swain's dependency model is used to calculate the conditional probability considering the dependency level between each CCF event in two different units. To perform the case study, the inter-unit CCF events of emergency diesel generators (EDGs) and alternate AC diesel generators (AAC DGs) in 4 units of different pressurized water reactor (PWR) types were analysed in the case of the multi-unit loss of off-site power (MULOOP). It is expected that methodologies in this study will contribute to the multi-unit level 1 PSA model development as well as evaluating the site risk in the future.