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Topic-level social influence analysis has been playing an important role in the online social networks like microblogs. Previous works usually use the cumulative number of links, such as the number of followers, to measure users' topic-level influence in a static network. However, they ignore the dynamics of influence and the methods they proposed can not be applied to social streams. To address the limitations of prior works, we firstly propose a novel topic-level influence over time (TIT) model integrating the text, links and time to analyze the topic-level temporal influence of each user. We then design an influence decay based approach to measure users' topic-level influence from the learned temporal influence. In order to track the influencers in data streams, we combine TIT and the influence decay method into a united online model (named oTIT), which is applicable to dynamic scenario. Through extensive experiments, we demonstrate the superiority of our approach, compared with the baseline and the state-of-the-art method. Moreover, we discover influence exhibits significantly different variation patterns over different topics, which verifies our viewpoint and gives us a new angle to understand its dynamic nature.

Roux-en-Y gastric bypass (RYGB) is a popular surgery to reduce the body weight of obese patients. Although food intake is restricted by RYGB, drug absorption is also decreased. The purpose of this study was to develop novel self-nanoemulsifying drug delivery systems (SNEDDS) for enhancing the oral delivery of silymarin, which has poor water solubility. The SNEDDS were characterized by size, zeta potential, droplet number, and morphology. A technique of RYGB was performed in Sprague-Dawley rats. SNEDDS were administered at a silymarin dose of 600 mg/kg in normal and RYGB rats for comparison with silymarin aqueous suspension and polyethylene glycol (PEG) 400 solution. Plasma silibinin, the main active ingredient in silymarin, was chosen for estimating the pharmacokinetic parameters. SNEDDS diluted in simulated gastric fluid exhibited a droplet size of 190 nm with a spherical shape. The nanocarriers promoted silibinin availability via oral ingestion in RYGB rats by 2.5-fold and 1.5-fold compared to the suspension and PEG 400 solution, respectively. A significant double-peak concentration of silibinin was detected for RYGB rats receiving SNEDDS. Fluorescence imaging showed a deeper and broader penetration of Nile red, the fluorescence dye, into the gastrointestinal mucosa from SNEDDS than from PEG 400 solution. Histological examination showed that SNEDDS caused more minor inflammation at the gastrointestinal membrane as compared with that caused by PEG 400 solution, indicating a shielding of direct silymarin contact with the mucosa by the nanodroplets. SNEDDS generally showed low-level or negligible irritation in the gastrointestinal tract. Silymarin-loaded SNEDDS were successfully developed to improve the dissolution, permeability, and oral bioavailability of silymarin. To the best of our knowledge, this is the first investigation reporting the usefulness of SNEDDS for improving drug malabsorption elicited by gastric bypass surgery.

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