In-situ deposition of POMA/ZnO nanorods array film by vapor phase polymerization for detection of trace ammonia in human exhaled breath at room temperature.

The o-methoxyaniline (OMA) monomer was polymerized in-situ by vapor phase polymerization to form uniform and dense poly-o-methoxyaniline (POMA) film on the surface of ZnO nanorods array film which was pre-prepared by hydrothermal method. The as-prepared POMA/ZnO composite shows the best response at 40 min of vapor phase polymerization time. The response to 100 ppm ammonia at 25 °C is 8.88. The recovery time of 136 s has a certain advantage in the reported room temperature ammonia sensors. The lowest detectable concentration is as low as 0.01 ppm. The fast recovery time and low detection limit make the sensor have broad application prospects. In order to explore the response mechanism of POMA/ZnO composite to ammonia gas, the work function of POMA and ZnO and corresponding band gap energies were tested respectively. And the effect of the formation of p-n heterostructure on gas response was further explored. The actual application test results reflect that the sensor can effectively identify NH3 in the mixed gas during the production, storage and transportation of NH3. This can provide real-time early warning of NH3 leakage. Especially, the sensor can detect trace amount of NH3 in the human body's exhaled breath which is expected to realize the preliminary screening of patients with kidney disease through the detection of exhaled breath in the medical field.

Synthesis and characterization of biocompatible antimicrobial N-halamine-functionalized titanium dioxide core-shell nanoparticles.

As one of the most powerful biocides, N-halamine based antimicrobial materials have attracted much interest due to their non-toxicity, rechargeability, and rapid inactivation against a broad range of microorganisms. In this study, novel titanium dioxide-ADMH core-shell nanoparticles [TiO2@poly (ADMH-co-MMA) NPs] were prepared via miniemulsion polymerization using 3-allyl-5,5-dimethylhydantoin (ADMH) and methyl methacrylate (MMA) with nano-TiO2. The produced nanoparticles were characterized by FT-IR, TEM, TGA, and XPS. The UV stability of N-halamine nanoparticles has been improved with the addition of titanium dioxide. After chlorination treatment by sodium hypochlorite, biocidal efficacies of the chlorinated nanoparticles against S. aureus (ATCC 6538) and E. coli O157:H7 (ATCC 43895) were determined. The nanoparticles showed excellent antimicrobial properties against bacteria within brief contact time. In addition, in vitro cell cytocompatibility tests showed that the antibacterial nanoparticles had good biocompatibility.

[Observation of the roots and root canals of 442 maxillary first premolars].

PURPOSE: To investigate the root and root canal anatomical features of maxillary first premolars in 422 teeth. METHODS: 422 maxillary first premolars were collected to statistically analyze the root types by sex and to observe the root canals by clearing technique; Vertucci's classification was adopted to get the percentage of each root canal type. The data were analyzed with SPSS11.5 software package. RESULTS: (1)Significant gender difference was found in 422 teeth in terms of the percentage of one root(total 57.36%; male 33.58%; female 62.68%), two roots(total 41.47%; male 62.68%; female 33.33%) and three roots(total 1.18%; male 3.73%; female 0%) (P<0.01). (2)In the 422 transparent specimens of the teeth, totally 9 types of root canals were discovered with the percentage of type I(10.12%), II(10.60%), III(6.02%), IV(56.63%), V(12.05%), VI(1.93%), VII(0.72%), VIII(1.45%), IX(0.48%). CONCLUSIONS: Understanding of the various and gender-different morphology of the roots and complex root canals of maxillary first premolars, is of great value for the diagnosis and root canal therapy.