A facile method to improve the stability of γ-cyclodextrin metal-organic frameworks (γ-CD-MOFs) in an aqueous environment has been developed through the incorporation of hydrophobic C60 in their matrices, and the resulting hybrid materials were exploited for drug delivery applications.

BackgroundThe current oral health status and possible dental risk factors among children in rural Shaanxi Province, western China are unreported. This study aimed to describe the oral health status and to analyze the possible risk factors for the oral health status in this population.MethodsA multi-stage cluster sampling method was used to survey 12- to 15-year-olds and 4- to 6-year-olds in villages in Shaanxi Province. The structured questionnaires were provided to the 12- to 15-year-olds and to the caregivers of the 4- to 6-year-olds to collect information on the subjects’ oral health knowledge, attitudes and behavior. A clinical examination was performed to assess dental caries and gingival bleeding (only 12- to 15-year-olds). SPSS 17.0 statistical software was used to analyze the data.ResultsThe decayed, missing, filled teeth (DMFT) index scores of 12- to 15-year-olds and 4-to 6-year-olds averaged 0.45 and 3.05, respectively. The caries prevalence was 23.9% in 12- to 15-year-olds and 67% in 4-to 6-year-olds. Additionally, 45.2% of the 12- to 15-year-olds had gingival bleeding and 62.8% had calculus. The oral health knowledge of the subjects was generally poor, whereas they held very positive attitudes toward oral health. A low number of participants reported that they brushed their teeth at least twice daily. Moreover, a statistically significant relationship was found between oral health knowledge scores, tooth brushing frequency and DMFT scores as well as gingival bleeding in the 12- to 15-year-olds. Frequency of sweets consumption was strongly related to dmft scores in the 4- to 6-year-olds.ConclusionThe oral health status, oral health knowledge and behaviors among village children in Shaanxi Province are poor. Oral health education to improve oral health knowledge and to increase the frequency of tooth brushing should be undertaken in the rural schools in western China.

Recent reports of externally triggered, controlled adsorption of carbon dioxide (CO 2 ) have raised the prospects of using stimuli responsive metal−organic frameworks (MOFs) for energy efficient gas storage and release. Motivated by these reports, here we investigate CO 2 adsorption mechanisms in photoresponsive PCN-123 and azo-IRMOF-10 frameworks. Using a combination of grand canonical Monte Carlo and first-principles quantum mechanical simulations, we find that the CO 2 adsorption in both frameworks is substantially reduced upon light-induced isomerization of azobenzene, which is in agreement with the experimental measurements. We show that the observed behavior originates from inherently weaker interactions of CO 2 molecules with the frameworks when azobenzene groups are in cis state rather than due to any steric effects that dramatically alter the adsorption configurations. Our studies suggest that even small changes in local environment triggered by external stimuli can provide a control over the stimuli responsive gas adsorption and release in MOFs.

This paper deals with the global output feedback tracking control problem for a class of switched nonlinear systems involving unknown parameters and unmeasured states multiplied by output nonlinearities. The switching information is assumed to be unobservable. To approach this purpose, a modified high-gain observer is introduced, and then an adaptive output feedback controller is constructed by adopting the adaptive backstepping technique. It is shown that, under arbitrary switching the proposed controller can guarantee all signals of the closed-loop system are globally uniformly bounded and the tracking error converges to a residual set that can be made arbitrarily small by properly selecting the design parameters. Simulation results are presented to verify the effectiveness of the proposed approach.