Arrays of Ultrathin CdS Nanoflakes with High-Energy Surface for Efficient Gas Detection.

It is fascinating and challenging to endow conventional materials with unprecedented properties. For instance, cadmium sulfide (CdS) is an important semiconductor with excellent light response; however, its potential in gas-sensing was underestimated owing to relatively low chemical activity and poor electrical conductivity. Herein, we demonstrate that an ideal architecture, ultrathin nanoflake arrays (NFAs), can improve significantly gas-sensing properties of CdS material. The CdS NFAs are grown directly on the interdigitated electrode to expose large surface area. Their thickness is reduced below the double Debye length of CdS, permitting to achieve a full depletion of carriers. Particularly, the prepared CdS nanoflakes are enclosed with high-energy {0001} facets exposed, which provides more active sites for gas adsorption. Moreover, the NFAs exhibit the light-trapping effect, which further enhances their gas sensitivity. As a result, the as-prepared CdS NFAs demonstrate excellent gas-sensing and light-response properties, thus being capable of dual gas and light detection.

Freestanding Ultrathin Metallic Nanosheets: Materials, Synthesis, and Applications.

Freestanding ultrathin metallic nanosheets (FUMNSs) with atomic thickness attract extensive attention because they display remarkable advantages over their bulk counterparts by virtue of their large specific area, high aspect ratio, and unsaturated surface coordination. The state of the art of research on FUMNSs is reviewed here, wherein the important progress from the aspects of material category, synthetic strategy, and practical application are introduced, and it is demonstrated that FUMNSs will play an important role in the fields of optoelectrics, catalysis, and magnetism.

[Detection and functional analysis of CD-4+ CD-25+ regulatory T cells in the peripheral blood of patients with generalized aggressive periodontitis].

OBJECTIVE: To investigate the changes of proportion and suppression function of CD-4+ CD-25+ regulatory T cells in the peripheral blood of patients with aggressive periodontitis. METHODS: Flow cytometric analysis was used to detect the frequency of CD-4+ CD-25+ regulatory T cells in the peripheral blood of 16 patients with generalized aggressive periodontitis and 17 patients with chronic periodontitis, as well as 17 periodontal healthy controls. Furthermore, CD-4+ CD-25+ regulatory T cells and CD-4+ CD-25- T cells were separated from peripheral blood of each enrolling subject using magnetic cell sorting technology. The direct suppression effect of CD-4+ CD-25+ regulatory T cells on CD-4+ CD-25- T lymphocytes proliferation was performed by the mixed lymphocytes reaction and measured by 3H-thymidine radioactive assay. RESULTS: The patients with generalized aggressive periodontitis had a lower frequency of CD4+ CD-25+ regulatory T cells (9.71 +/- 4.01)% in the peripheral blood than periodontal healthy controls [(14.72 +/- 3.51)%] and chronic periodontitis patients [(17.01 +/- 5.16 )%], P < 0.05. A significant decrease was found in the suppression function of CD-4+ CD-25+ regulatory T cells from peripheral blood of patients with generalized aggressive periodontitis when co-cultured with CD-4+ CD-25- T lymphocytes in the proportion of 2 : 1, 1 : 1 and 1 : 2 as compared with chronic periodontitis patients and periodontal healthy controls (P < 0.05). CONCLUSIONS: Diminished numbers and decreased suppression function of CD-4+ CD-25+ regulatory T cells were found in patients with generalized aggressive periodontitis.

[Clinical management of lateral canal perforation with MTA].

PURPOSE: To evaluate the clinical effect of repair of lateral root canal perforation with mineral trioxide aggregate (MTA). METHODS: 18 teeth with root canal perforation were selected. The root canals were shaped and cleaned, and then obturated with gutta-percha before or after MTA was used to repair the perforation. RESULTS: The postoperative X-ray films showed that the perforation of 17 teeth was repaired well, except one tooth with large and infected perforation. 10 cases showed a little over-filling of MTA. 16 patients were recalled and declared their teeth to be asymptomatic. The recall radiographs indicated that the apical radiolucent areas of teeth with pre-existing apical lesion decreased apparently or disappeared completely. No new radiolucency was found. CONCLUSIONS: MTA is effective in treatment of teeth with root canal perforation, even though the material is over-filled. Supported by 2004 Key Clinical Project of Medical Systems Affiliated to Ministry of Health and Natural Science Foundation of Guangdong Province (Grant No.5300624).

[Use of angulated radiograph in clinical judgement of obturation quality of molars with multiple root canals].

OBJECTIVE: To investigate different angle projection technique for clinical judgment of obturation quality of molars with multiple root canals. METHODS: Eighty-seven maxillary first molars with second mesiobuccal canal (MB2) and 105 mandibular first molars were selected. The canals were instrumented by Ni-Ti rotary instruments and obturated with lateral condensation technique. To judge the obturation quality of the root canals, the radiograph was taken at a horizontal angles of 0 and 20 - 30 degrees from distal direction of the tooth after the treatment. RESULTS: For maxillary first molars, periapical radiographs showed 23.0% of MB2. Distally angulated radiographs showed 81.6% of MB2. For mandibular first molars, periapical radiographs showed 38.1% of mesiobuccal and mesiolingual canals, and distally angulated radiographs showed 90.5% of two mesial root canals. CONCLUSIONS: Most buccal-lingual distributed root canals of the first molar can be shown more clearly by distally angulated radiographs.