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BackgroundIn the long-term uninterrupted work of the real-time on-line monitoring system of water radioactivity, the spectrum drift, line broadening and shift of peak position are caused by the temperature change of the detector and various electronic components and the aging of components, which leads to the difficulty of spectral line analysis and the error of analytical results.PurposeThis study aims to develop a calibration device for real-time on-line monitoring system of water radioactivity based on cerium bromide detector.MethodsThe device was designed to consists of 137Cs standard source (exemption source), lead block, lead chamber with calibration hole and linear motor. The optimum opening radius of the calibration hole and the optimum thickness of the lead block were obtained by Monte Carlo simulation. The standard 137Cs source was used as the standard reference peak, and the calibration of peak position and peak area, the peak position drift and peak area of 137Cs full-energy peak was analyzed by software with real-time gain calculation and parameters adjustment. Finally, the device was applied to the field application verification.Results & ConclusionsResults of Monte Carlo simulation indicate that the optimum radius of the calibration hole is 2.2 cm and the optimum thickness of the lead block is 5 cm. The verification results shows that the device can limit the change of peak position and peak area to ±1% and ±5%, respectively.

Meckel syndrome (MKS), also known as the Meckel–Gruber syndrome, is a severe pleiotropic autosomal recessive developmental disorder caused by dysfunction of the primary cilia during early embryogenesis. The diagnostic criteria are based on clinical variability and genetic heterogeneity. Mutations in the MKS1 gene constitute approximately 7% of all MKS cases. Herein, we present a non-consanguineous couple with three abnormal pregnancies as the fetuses showed MKS-related phenotypes of the central nervous system malformation and postaxial polydactyly. Whole-exome sequencing identified two novel heterozygous mutations of MKS1 : c.350C>A and c.1408-14A>G. The nonsense mutation c.350C>A produced a premature stop codon and induced the truncation of the MKS1 protein (p.S117*). Reverse-transcription polymerase chain reaction (RT-PCR) showed that c.1408-14A>G skipped exon 16 and encoded the mutant MKS1 p.E471Lfs*92. Functional studies showed that these two mutations disrupted the B9–C2 domain of the MKS1 protein and attenuated the interactions with B9D2, the essential component of the ciliary transition zone. The couple finally got a healthy baby through preimplantation genetic testing for monogenic disorder (PGT-M) with haplotype linkage analysis. Thus, this study expanded the mutation spectrum of MKS1 and elucidated the genetic heterogeneity of MKS1 in clinical cases. [ABSTRACT FROM AUTHOR]