Objective To analyze the pollution characteristics of PM_2.5-bound polycyclic aromatic hydrocarbons (PAHs) during the non-heating period, heating period, and haze period in Harbin, and infer their possible sources, and to evaluate their impact on population carcinogenesis. Methods From 2020 to 2022, sampling points were set up in different districts of Harbin. PM_2.5 samples were regularly collected every month to analyze the contents of 10 types of PM_2.5-bound 4-6 rings PAHs. The pollution characteristics of PAHs were analyzed during different monitoring periods (non-heating period, heating period, and haze period). The excess carcinogenesis risks of PM_2.5-bound PAHs were assessed according to the Technical Specifications for Health Risk Assessment of Ambient Air Pollution and the U. S. Environmental Protection Agency (US EPA) risk assessment method. The characteristic ratio method and the positive matrix factorization (PMF) model were used to infer the sources of PAHs. Results The median mass concentrations of ambient PM_2.5-bound 4-6 rings PAHs (ΣPAHs) during the non-heating period, heating period, and haze period were 6.44 ng/m³, 37.85 ng/m³, and 106.79 ng/m³, respectively. During the heating season and haze period, the concentrations of benzo[a]anthracene, benzo[k]fluoranthene, pyrene and fluoranthene were relatively high. The excess carcinogenic risks for ASF_>16, ASF_2-16 and ASF_<2 caused by exposure to PM_2.5-bound 4-6rings PAHs during the heating season were 2.34×10^-6, 1.82×10^-6, and 0.88×10^-6, respectively, while the excess carcinogenic risks for the whole population during the heating season and haze period were 5.05×10^-6 and 1.75×10^-6, respectively. The results of the two source methods showed that the main characteristic elements during the heating season were fluoranthene, pyrene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[a]pyrene. According to the emission source standards, it was determined that the sources were mainly coal and biomass combustion, accompanied by traffic source emissions. Conclusion In Harbin, the PM_2.5-bound 4-6 rings PAHs during the haze period is significantly higher than that during the heating period. The pollution is mainly from coal combustion emissions, accompanied by continuous traffic source pollution. The exposure to PAHs during the heating period poses a potential carcinogenic risk to the population.

Objective:To analyze the genetic characteristics of hemagglutinin（HA）and neuraminidase（NA）of influenza A（H1N1）pdm09 viruses in Kunming during the 2022-2023 influenza season.Methods:A total of 15 strains of A（H1N1）pdm09 influenza virus isolated from sentinel hospital surveillance and from outbreaks from April 2022 to March 2023 in Kunming were chosen for sequencing. The genetic analysis，which included sequence alignment，homology analysis，construction of phylogenetic tree and amino-acid mutations analysis，was carried out using MAFFT version 7，MegAlign and MEGA 11.Results:Fourteen strains isolated during the 2022-2023 influenza season in Kunming belong to clade 6B.1A.5a.2a，and A/Kunming/284/2023 belonged to clade 6B.1A.5a.2a.1. They all diverged from the northern hemisphere vaccine strain A/Wisconsin/588/2019 in clade 6B.1A.5a.2 recommended by WHO during the 2022-2023 influenza season. Comparing with the HA of the vaccine strain：A186T and Q189E，which might cause the reduction of vaccine protection，were identified in Sb of 14 strains；P137S，K142R in Ca and A186T，Q189E in Sb were identified in A/Kunming/284/2023 and two strains isolated from Thailand. The four mutations at tow antigenic sites identified immune escape at the molecular level. Q189E in the 190-helix and E224A in the 220-loop，which might change the pathogenicity of A（H1N1）pdm09 viruses，were identified in 15 strains. Comparing with NA of the vaccine strain：S200N in 14 strains and S339L in 1 strain were identified in antigenic sites. The two mutations might reduce the protection of antibodies induced by NA.Conclusion:Strengthening influenza surveillance and timely detecting new variants in Kunming contributes to preventing the importation of foreign strains and issuing early warnings for influenza outbreaks.

Objective:To analyze the genetic characteristics of hemagglutinin（HA）and neuraminidase（NA）of influenza A（H1N1）pdm09 viruses in Kunming during the 2022-2023 influenza season.Methods:A total of 15 strains of A（H1N1）pdm09 influenza virus isolated from sentinel hospital surveillance and from outbreaks from April 2022 to March 2023 in Kunming were chosen for sequencing. The genetic analysis，which included sequence alignment，homology analysis，construction of phylogenetic tree and amino-acid mutations analysis，was carried out using MAFFT version 7，MegAlign and MEGA 11.Results:Fourteen strains isolated during the 2022-2023 influenza season in Kunming belong to clade 6B.1A.5a.2a，and A/Kunming/284/2023 belonged to clade 6B.1A.5a.2a.1. They all diverged from the northern hemisphere vaccine strain A/Wisconsin/588/2019 in clade 6B.1A.5a.2 recommended by WHO during the 2022-2023 influenza season. Comparing with the HA of the vaccine strain：A186T and Q189E，which might cause the reduction of vaccine protection，were identified in Sb of 14 strains；P137S，K142R in Ca and A186T，Q189E in Sb were identified in A/Kunming/284/2023 and two strains isolated from Thailand. The four mutations at tow antigenic sites identified immune escape at the molecular level. Q189E in the 190-helix and E224A in the 220-loop，which might change the pathogenicity of A（H1N1）pdm09 viruses，were identified in 15 strains. Comparing with NA of the vaccine strain：S200N in 14 strains and S339L in 1 strain were identified in antigenic sites. The two mutations might reduce the protection of antibodies induced by NA.Conclusion:Strengthening influenza surveillance and timely detecting new variants in Kunming contributes to preventing the importation of foreign strains and issuing early warnings for influenza outbreaks.

Objective: To understand the drinking water quality of rural schools in Harbin in the past five years. Methods: According to the requirements of Harbin municipal drinking water sanitation monitoring program, rural schools were monitored for drinking water in dry and wet periods, water quality was tested according to the standard test method for drinking water (GB/T 5750—2006), and water quality was evaluated according to the standard for drinking water (GB 5749—2006). Results: A total of 320 water samples were tested from 2014 to 2018, and the qualified rate was 75.63% in 5 years, which showed an increasing trend( χ 2=10.81, P <0.05). The qualified rate of drinking water in treated rural schools (79.41%) was higher than that in untreated rural schools(68.97%)( χ 2=4.38, P <0.05). Conclusion The drinking water sanitation of rural schools in Harbin is not optimistic. Supervision and monitoring of drinking water in rural schools, construction and management of treatment and disinfection facilities should be strengthened to ensure the safety of drinking water for teachers and students.

Objective To improve the usage of foam dressing at the sacrococcygeal region and observe its application effect. Methods A total of 80 hospitalized patients with high risk of pressure ulcer were chosen during May to December 2015 as study objects. Patients were drawn into the observation group and the control group, each group contained 40 members. Proper-cutting foam dressings and normal foam dressing were applied in patients by the observation group and the control group individually. Researchers made records by comparing and analyzing the usage time of dressing and the skin intact of two groups. Results The observation group used foam dressing (1.88±0.12) blocks per person, foam dressing use time was (3.87±0.34) d per block, and in the control group, they were (2.60±0.38) blocks per person, (2.13±0.89) d per block, there was significant difference between two groups (t=11.427, 11.551, P<0.05). The skin integrity rate of the observation group and the control group were 95.0%(38/40) and 75.0%(30/40), the difference was statistically significant (χ2=6.275, P<0.05). Conclusions This study shows that the foam dressing need to be cut appropriately before pasting so that the clinical nurses can observe patient's skin conveniently. Once the skin has pressure red, the nurse can take timely measures to deal with it, which can decrease the incidence of pressure sores. The cutting dressing prolongs the period of using without removing the viscose part, which also can reduce the medical expenses.