ABSTRACT
Objective@#To compare and investigate the physicochemical characteristics and antibacterial effect of ZnO nanofilms prepared by atomic layer deposition(ALD) at different deposition cycles.@*Methods@#According to different ALD cycles, four groups were set up (control group, 300, 600 and 1 200 cycles group). Using DEZn and water as precursors, ZnO nanofilms were prepared by ALD on the surface of pure titanium specimens. Surface morphology of the films was observed by scanning electron microscope (SEM); the element composition and crystal type of the films were observed by energy dispersive spectrometer (EDS) and X-Ray Diffraction (XRD); the hydrophilicity and thickness of the films were detected by water contact angle detector and ellipsometer. The cytotoxicity of the films was evaluated by CCK-8 assay. The antibacterial effect against S. aureus in vitro of the films was evaluated by optical density method.@*Results@#The surface morphology of the films was uniform and compact as shown through SEM. The grain size increased with the increase of the number of ALD cycles. EDS results showed that the films were mainly composed of Zn and O elements. XRD results confirmed that the composition of the films was ZnO. Results of water contact angle showed that the films were hydrophobic. The thickness of the films was nanoscale and there was a linear relationship between the thickness and ALD cycles. All experimental groups showed no cytotoxicity. The 1 200 cycles group showed the highest antibacterial rate of 65.9% and 52.3% at 24 and 48 hours respectively, which was the best among all experimental groups. @*Conclusion@#The ZnO nanofilms prepared by ALD at different cycles on pure titanium surface are uniform and compact. Thickness of the films increases with the increase of ALD cycles. The films have good biocompatibility and anti-S. aureus effect in vitro. The 1 200 cycles group has the best antibacterial effect.
ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the colorectal cancer incidence among compliers and non-compliers in the population of colorectal cancer screening area, and to provide scientific basis for health economic evaluation of cancer screening.</p><p><b>METHODS</b>By screening different years build queue, to retrospectively compare the data of colorectal cancer screening from January 1, 2008 to December 31, 2013 and the data of cancer registration, and to analyze the colorectal cancer incidence rates among screening compliers and non-compliers, and to compare the average intervals between the end of screening and clinical cancer diagnosis using SPSS 19 statistical software. Mantel-Haenszel test was performed with a statistical significance level of α = 0.05.</p><p><b>RESULTS</b>The non-compliance rate was 38.24% among males and 28.49% among females (P < 0.001). The non-compliance rate was highest in the 40-44 and 70-74 years age groups and lowest in the 50-59 years age group. The compliers of the screening were followed up for 476,049 person-years, and there were 51 cases of colorectal cancer, with an incidence rate of 10.71/100,000. The non-compliers of the screening were followed up for 259 183 person-years, and there were 66 cases of colorectal cancer, with an incidence rate of 25.46/100,000, which was 1.38 times higher than that of the compliance group (χ2 = 21.699, P < 0.001). The incidence rate of colorectal cancer among subjects who were positive in initial screening but refused to receive an electronic colonoscopy was as high as 164.40/100,000, and the average delay time was 20.8 ± 16.8 months.</p><p><b>CONCLUSIONS</b>The colorectal cancer screening adherence among women is better than among men, and that of 50-54 years and 55-59 years age groups is better than in other age groups. The subsequent incidence rate of colorectal cancer in the non-compliance group is significantly higher than that of the compliance population.</p>