Information management system of nuclear medicine (IMSNM) is an important part of modem medical information system.It is used for the scientific management of clinical works,and classification and storage of patient data and examination data (words and images).With the help of IMSNM,standardization,automation and digitization of clinical operation protocols,the scientific and normalized management,the unification of image storage and viewing could be achieved.The IMSNM plays an important role in the health care,education and scientific research.This study mainly describes the design and application of IMSNM.

【Objective】 To investigate the electronic screen exposure of preschool children in Longhua District of Shenzhen, and to analyze the influencing factors. 【Methods】 A total of 25 266 children in kindergarten in Longhua District of Shenzhen were selected as study subjects. A self-designed questionnaire (completed by their guardians) was used to investigate the use of electronic products in the families of preschoolers in April 2019. 【Results】 A total of 23 407 valid questionnaires were collected in this survey, of which 12 593 (53.80%) were boys and 10 814 (46.20%) were girls; and 17 188(73.43%) children were 5 years old. Among the surveyed children, the rate of excessive exposure to electronic screens (>1h/d) was 37.72%, and 6.40% of preschool children used electronic products for more than 2 hours per day. There were statistically significant differences between the excessive exposure group and the non-excessive exposure group in gender, household registration, parents′ educational level, average monthly household income, whether exclusive electronic products,whether restriction of children′s use of electronic products, whether living with elders, only children or not, and the type of main caregiver (P<0.05). Multivariate binary Logistic regression analysis showed that girls, mothers with college education or above,not living with elders,primary caregivers being parents or nannies/others,and no exclusive electronic products were protective factors for children′s excessive exposure to electronic products(P<0.05).Non-household resident population,not-only child,and non-restriction of children′s use of electronic products were risk factors for children′s excessive exposure to electronic products(P<0.05). 【Conclusions】 The excessive use of electronic products in preschoolers is a common phenomenon in Longhua district, Shenzhen. Therefore, it is necessary to strengthen the intervention on the use time of electronic products in preschoolers, and pay more attention to the influence of family environmental factors.

Polyethylene terephthalate (PET) is a synthetic polymer consisting of ester bond-linked terephthalate and ethylene glycol. Tremendous amounts of PET have been produced and majority of them enters terrestrial and marine environment as wastes, posing serious threats to the global ecosystems. In 2016, a PET hydrolase from a PET-assimilating bacterium Ideonalla sakaiensis was reported and termed as IsPETase. This enzyme outperforms other PET-hydrolyzing enzymes in terms of its PET hydrolytic activity at ambient temperature, thus holds a great promise for PET biodegradation. In order to improve IsPETase activity, we conducted structure-based engineering to modify the putative substrate-binding tunnel. Among the several variants to the N233 residue of IsPETase, we discovered that the substitution of N233 with alanine increases its PET hydrolytic activity, which can be further enhanced when combined with a R280A mutation. We also determined the X-ray crystal structure of the IsPETase N233A variant, which shares nearly identical fold to the WT protein, except for an open end of subsite Ⅱ. We hypothesized that the smaller side chain of N233A variant might lead to an extended subsite Ⅱ for PET binding, which subsequently increases the enzymatic activity. Thus, this study provides new clues for further structure-based engineering of PETase.
Burkholderiales/enzymology* ; Hydrolases/genetics* ; Polyethylene Terephthalates/metabolism* ; Protein Engineering