[Study of factors affecting tooth discoloration during fixed orthodontics in vitro].

Purpose: To investigate effects of acid etching, adhesives, brackets and debonding process on tooth color during direct bonding technique.

Methods: One hundred freshly extracted premolars were divided into blank control, acid etching, adhesive, acid etching+adhesive and acid etching+adhesive+bracket group. Computerized colorimeter was utilized to evaluate L*, a* and b* of tooth color parameters before treatment, 7 days and 30 days after treatment.

Health risk assessment of inhalable particulate matter in Beijing based on the thermal environment.

Inhalable particulate matter (PM10) is a primary air pollutant closely related to public health, and an especially serious problem in urban areas. The urban heat island (UHI) effect has made the urban PM10 pollution situation more complex and severe. In this study, we established a health risk assessment system utilizing an epidemiological method taking the thermal environment effects into consideration.

[Eco-efficiency of Jiaozuo industry sectors].

Jiaozuo city was taken as a representative industry city and its industry energy consumption and industry emissions such as wastewater,solid waste, SO2, dust and so on were selected as corresponding environmental loads. The contribution rate to the environmental loads and eco-efficiencies of Jiaozuo industry sectors were analyzed quantitatively. The results show that, the industry sector with the highest energy eco-efficiency is Mining and Processing of Ferrous Metal Ores (FMM), 43.

[3-D finite element analysis on center of resistance of upper anterior teeth].

Purpose: To investigate the location of center of resistance(CRe) of six upper anterior teeth.

Methods: A three-dimensional finite element model of premaxillary bone and anterior teeth was established in ANSYS 8.1 software.

Valuing health effects from the industrial air pollution in rural Tianjin, China.

High concentrations of air pollutants such as total suspended particulates (TSP) and sulfur dioxide (SO2) have serious impacts on nearby populations. In this paper, a survey of rural Tianjin residents' willingness-to-pay for health improvement was reported on, and the MBDC (multiple bounded discrete choice) model was adopted to study the respondents' willingness-to-pay to prevent respiratory illnesses. The results showed that the willingness-to-pay for health improvement was affected by respondents' health condition, work situation and environmental awareness, but not by personal habits, such as smoking.