The nanosized hydroxyapatite substituted by fluoride and carbonate ions （CFHA） had been synthesized by aqueous precipitation method. CFHA had been considered as potential bone graft material for orthopedic and denta...The nanosized hydroxyapatite substituted by fluoride and carbonate ions （CFHA） had been synthesized by aqueous precipitation method. CFHA had been considered as potential bone graft material for orthopedic and dental applications. The objective of this study was to determine the effects of simultaneously incorporated CO2/3- and F- on the substitution type and content. The morphologies of CFHAs were observed by TEM. The carbonate substitution type and content were characterized by FTIR. The fluoride contents were determined by F-selective electrode. The phase compositions and crystallinity of the samples were investigated by XRD. The fluoride and carbonate contents of CFHA increase with the dopant concentrations nonlinearly, The carbonate substitution has much more obvious effect on morphology compared with the fluoride substitution. The co-existence of CO2/3-and F- ions can influence the corresponding substitution fraction. The isomorphic substitution of sodium for calcium in the substitution process of CO2/3-can improve crystal degree and favor the B-type substitutions. Due to the closeness of the ion radii and equivalent substitution of F- and OH-, F- will occupy the OH- sites of HA crystals more easily, compelling most of the CO2/3- to be located in the B sites.展开更多
The new crystalline V-Ti-silicalite with mesoporous MCM-41 type molecular sieve structure is synthesized hydrothermally; The framework IR spectra associated with ESR, Si-29 MAS NMR, DRS and XPS data shows that V and T...The new crystalline V-Ti-silicalite with mesoporous MCM-41 type molecular sieve structure is synthesized hydrothermally; The framework IR spectra associated with ESR, Si-29 MAS NMR, DRS and XPS data shows that V and Ti are simultaneously incorporated into V-TiMCM-41 framework.展开更多
There are some Indications thtt herpes aimplex virus (HSV) may be mutagenic. Specific chromosomal changes have also been demonstrated In cultured cells infected with HSV. To further Investigate the mutagenic activity ...There are some Indications thtt herpes aimplex virus (HSV) may be mutagenic. Specific chromosomal changes have also been demonstrated In cultured cells infected with HSV. To further Investigate the mutagenic activity of HSV type 2 (HSV-2) we used mouse skin as a model system for cardnogenetls. Inoculation of the back skin of 4-week-old Sencar mke with live virus twice per week for one week or with Inactivated virus twice per week for two weeks was used to Initiate the mouse akin. After Initiation with HSV-2, 12-O-tetradecanoylphorbol-13-acetale(TPA) was applied twice weekly for 50 weeks as a promoter. During a period of 52 weeks, no skin carcinoma was found In the experimental groups, whereas 55% of control mice treated with 9, 10-dlmethy1-1, 2- benzanthracene (DMBA ) and then with TPA-developed skin carcinoma. The results demonstrate that HSV-2 could not substitute for DMBA in this animal model of two-stage skin carcinogenesis.展开更多
文摘The nanosized hydroxyapatite substituted by fluoride and carbonate ions （CFHA） had been synthesized by aqueous precipitation method. CFHA had been considered as potential bone graft material for orthopedic and dental applications. The objective of this study was to determine the effects of simultaneously incorporated CO2/3- and F- on the substitution type and content. The morphologies of CFHAs were observed by TEM. The carbonate substitution type and content were characterized by FTIR. The fluoride contents were determined by F-selective electrode. The phase compositions and crystallinity of the samples were investigated by XRD. The fluoride and carbonate contents of CFHA increase with the dopant concentrations nonlinearly, The carbonate substitution has much more obvious effect on morphology compared with the fluoride substitution. The co-existence of CO2/3-and F- ions can influence the corresponding substitution fraction. The isomorphic substitution of sodium for calcium in the substitution process of CO2/3-can improve crystal degree and favor the B-type substitutions. Due to the closeness of the ion radii and equivalent substitution of F- and OH-, F- will occupy the OH- sites of HA crystals more easily, compelling most of the CO2/3- to be located in the B sites.
文摘The new crystalline V-Ti-silicalite with mesoporous MCM-41 type molecular sieve structure is synthesized hydrothermally; The framework IR spectra associated with ESR, Si-29 MAS NMR, DRS and XPS data shows that V and Ti are simultaneously incorporated into V-TiMCM-41 framework.
文摘There are some Indications thtt herpes aimplex virus (HSV) may be mutagenic. Specific chromosomal changes have also been demonstrated In cultured cells infected with HSV. To further Investigate the mutagenic activity of HSV type 2 (HSV-2) we used mouse skin as a model system for cardnogenetls. Inoculation of the back skin of 4-week-old Sencar mke with live virus twice per week for one week or with Inactivated virus twice per week for two weeks was used to Initiate the mouse akin. After Initiation with HSV-2, 12-O-tetradecanoylphorbol-13-acetale(TPA) was applied twice weekly for 50 weeks as a promoter. During a period of 52 weeks, no skin carcinoma was found In the experimental groups, whereas 55% of control mice treated with 9, 10-dlmethy1-1, 2- benzanthracene (DMBA ) and then with TPA-developed skin carcinoma. The results demonstrate that HSV-2 could not substitute for DMBA in this animal model of two-stage skin carcinogenesis.
