Density functional theory calculations were performed to study the structures and relative stability of the gadolinium complexes, Gd（H2O）n^3＋ （n=8,9）, in vacuo and in aqueous solution. The polarizable continuum m...Density functional theory calculations were performed to study the structures and relative stability of the gadolinium complexes, Gd（H2O）n^3＋ （n=8,9）, in vacuo and in aqueous solution. The polarizable continuum model with various radii for the solute cavity was used to study the relative stability in aqueous solution. The calculated molecular geometries for n=8 and 9 obtained in vacuo are consistent with those observed in experiments. It was found that while the nona-aqua complex is favored in the gas phase, in aqueous solution the octa-aqua conformation is preferred. This result, independent of the types of cavities employed, is in agreement with the experimental observation. The reliability of the present calculation was also addressed by comparing the calculated and experimental free energy of hydration, which revealed that the UA0, UAHF, and UAKS cavities are most appropriate when only the first solvation shell is treated explicitly.展开更多
This paper describes a three-dimensional structured light scanning system to generate a virtual model of a dental arch, from the patient＇s mouth, and the scheme ofa 2 ＋ 1 DOF （degree of freedom） parallel/serial Ro...This paper describes a three-dimensional structured light scanning system to generate a virtual model of a dental arch, from the patient＇s mouth, and the scheme ofa 2 ＋ 1 DOF （degree of freedom） parallel/serial Robot for implant positioning, both positioned on a platform held in a fixed position with respect to the patient＇s head. Presently, dental prosthesization requires quite a long time to be completed. This process, in fact, involves the detection of the shape of the dental arch, its plaster model generation, scanning of it, prosthesis preparation and its implant. The procedur＇e is even longer when use of dental implants is required, while early loading of the implants is considered a positive solution. Current research effort is focused on the development of devices for the direct intra-oral determination of the shape of dental prostheses and inserts. These devices, however, are able to detect limited portions of the dental arch, since they must be hand-held by the doctor without external supports, and this may produce relatively large errors due to the sum of relatively small ones. Furthermore, to place an implant correctly, the doctor can use a new system to guide the implant position, but this requires sending the information in Sweden to obtain a special mask in return.展开更多
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.10804001, No.10674002, and No.20773024）, the National High Technology Research and Development Program of China （No.2006AA09Z243-3）, and the Program for Innovative Research Team in Anhui Normal University of China.
文摘Density functional theory calculations were performed to study the structures and relative stability of the gadolinium complexes, Gd（H2O）n^3＋ （n=8,9）, in vacuo and in aqueous solution. The polarizable continuum model with various radii for the solute cavity was used to study the relative stability in aqueous solution. The calculated molecular geometries for n=8 and 9 obtained in vacuo are consistent with those observed in experiments. It was found that while the nona-aqua complex is favored in the gas phase, in aqueous solution the octa-aqua conformation is preferred. This result, independent of the types of cavities employed, is in agreement with the experimental observation. The reliability of the present calculation was also addressed by comparing the calculated and experimental free energy of hydration, which revealed that the UA0, UAHF, and UAKS cavities are most appropriate when only the first solvation shell is treated explicitly.
文摘This paper describes a three-dimensional structured light scanning system to generate a virtual model of a dental arch, from the patient＇s mouth, and the scheme ofa 2 ＋ 1 DOF （degree of freedom） parallel/serial Robot for implant positioning, both positioned on a platform held in a fixed position with respect to the patient＇s head. Presently, dental prosthesization requires quite a long time to be completed. This process, in fact, involves the detection of the shape of the dental arch, its plaster model generation, scanning of it, prosthesis preparation and its implant. The procedur＇e is even longer when use of dental implants is required, while early loading of the implants is considered a positive solution. Current research effort is focused on the development of devices for the direct intra-oral determination of the shape of dental prostheses and inserts. These devices, however, are able to detect limited portions of the dental arch, since they must be hand-held by the doctor without external supports, and this may produce relatively large errors due to the sum of relatively small ones. Furthermore, to place an implant correctly, the doctor can use a new system to guide the implant position, but this requires sending the information in Sweden to obtain a special mask in return.
