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We demonstrate a novel, feasible strategy for practical application of one-dimensional photodetectors by integrating a carbon nanotube and TiO(2) in a core-shell fashion for breaking the compromise between the photogain and the response/recovery speed. Radial Schottky barriers between carbon nanotube cores and TiO(2) shells and surface states at TiO(2) shell surface regulate electron transport and also facilitate the separation of photogenerated electrons and holes, leading to ultrahigh photogain (G = 1.4 × 10(4)) and the ultrashort response/recovery times (4.3/10.2 ms). Additionally, radial Schottky junction and defect band absorption broaden the detection range (UV-visible). The concept using metallic core oxide-shell geometry with radial Schottky barriers holds potential to pave a new way to realize nanostructured photodetectors for practical use.

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To improve the resolution of contrast-assisted imaging systems, we previously developed a 25-MHz microbubbles-destruction/replenishment imaging system with a spatial resolution of 160 X 160 microm. The goal of the present study was to propose a new approach for functionally evaluating the microvascular volumetric blood flow based on this high-frequency, ultrasound imaging system. The approach includes locating the perfusion area and estimating the blood flow velocity therein. Because the correlation changes between before and after microbubble destruction in two adjacent images, a correlated-based approach was introduced to detect the blood perfusion area. We also have derived a new sigmoid-based model for characterizing the microbubbles replenishment process. Two parameters derived from the sigmoid-based model - the rate constant and inflection time - were adopted to evaluate the blood flow velocity. This model was validated using both simulations and in vitro experiments for mean flow velocities ranging from 1 to 10 mm/s, which showed that the model was in good agreement with simulated and measured microbubble-replenishment time-intensity curves. The results indicate that the actual flow velocity is highly correlated with the estimates of the rate constant and the reciprocal of the inflection time. B-mode imaging experiments for mean flow velocities ranging from 0.4 to 2.1 mm/s were used to assess the volumetric flow in the microcirculation. The results indicated the high correlation between the actual volumetric flow rate and the product of the estimated perfusion area and rate constant, and the reciprocal of the inflection time. We also found that the boundary of the microbubble destruction volume significantly affected estimations of the flow velocity. The perfusion area can be located, and the corresponding flow velocity can be estimated simultaneously in a one-stage, microbubble-destruction/replenishment process, which makes the assessment of the volumetric bloo- d flow in the microcirculation feasible using a real-time, high-frequency ultrasound system.

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OBJECTIVE: To investigate the changes in characteristics of periodontal pathogens in subgingival plaque of patients with puberty gingivitis and its relevance with clinical symptoms. METHODS: A total of 108 subgingival plaque samples were collected from 30 patients with puberty gingivitis (Group G), 9 cases of chronic periodontitis (Group P) and 15 healthy controls (Group H). The age of the 54 participants was from 11 to 17. The black-pigmented bacteria (BPB), Fusobacterium nucleatum (Fn), Actinobacillus actinomycetemcomitans (Aa), Actinomyces were detected using bacterial culture. The probing depth (PD), gingival index (GI), bleeding index (BI) and attachment loss (AL) were also recorded. RESULTS: In all these three groups, the detection rates of black-pigmented bacteria were: 3%, 30% and 100%; Fn were: 30%, 68% and 94%, statistically significantly different (P < 0.01). The lgCFU/ml of black-pigmented bacteria and Actinomyces was higher in mild-moderate group [(3.8 +/- 0.7) and (5.3 +/- 0.9)] than in Group H (P < 0.001). The lgCFU/ml of black-pigmented bacteria and Fn significantly was higher in severe inflammation group [(4.7 +/- 1.2) and (4.4 +/- 0.8)] than in the mild-moderate group (P < 0.01). The lgCFU/ml of black-pigmented bacteria, Fn and Aa was higher in severe gingivitis group [(6.6 +/- 1.0), (5.5 +/- 1.0) and (4.2 +/- 1.7)] than in mild gingivitis group (P < 0.01). The detection rate and lgCFU/ml of black-pigmented bacteria, Fn and Aa were both positively correlated with BI, PD and AL. CONCLUSIONS: In the stage of severe gingivitis, the periodontal pathogens increased markedly, suggesting that risk of further destruction of periodontal tissue may exist.

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A high frequency contrast-assisted destruction/reperfusion imaging system has been developed to improve image resolution in previous study. Our goal in this work is to build a fast and robust algorithm to evaluate volumetric microcirculation blood flow. The microcirculation flow rate is determined by the multiplication of perfusion area and corresponding blood flow velocity mapping. The blood flow velocity can be estimated from B-mode time-intensity curves (TICs). Two new methods, correlation-based approach (CBA) and sum-absolute-difference approach (SADA), are proposed to locate and assess perfusion area. In vitro experiments were introduced to test the performance of two approaches. The results indicate a good correlation between the actual flow rate and the estimated volumetric flow rate. Potential applications of this blood flow estimation method include high-resolution flow assessment in small animal tumor and glaucoma models and the evaluation of superficial vasculature in clinical studies.