Recommender Systems with Characterized Social Regularization

Social recommendation, which utilizes social relations to enhance recommender systems, has been gaining increasing attention recently with the rapid development of online social network. Existing social recommendation methods are based on the fact that users preference or decision is influenced by their social friends' behaviors. However, they assume that the influences of social relation are always the same, which violates the fact that users are likely to share preference on diverse products with different friends. In this paper, we present a novel CSR (short for Characterized Social Regularization) model by designing a universal regularization term for modeling variable social influence. Our proposed model can be applied to both explicit and implicit iteration. Extensive experiments on a real-world dataset demonstrate that CSR significantly outperforms state-of-the-art social recommendation methods.Comment: to appear in CIKM 201

Studies of hydrophobic organic pollutant interactions with cyclodextrin: implication for groundwater remediation

Henry’s Law constants of several common, subsurface hydrophobic organic pollutants (HOPs) including trichloroethylene (TCE), perchloroethylene (PCE) and benzene, toluene, ethylbenzene and o-xylene (BTEX), were measured over a range of temperatures (35, 45, 55 and 65°C) and cyclodextrin (CD) concentrations (0, 10, 20, 50 and 100 g L-1). In aqueous CD solutions, Henry’s constant values decrease by a power law relationship with increasing CD concentration due to an apparent solubility enhancement caused by HOP partitioning to the hydrophobic cavity of CD molecules. The temperature dependence of air-water partitioning under the influence of CD was well described by the van’t Hoff equation for all HOPs tested. A three-phase equilibrium model was used to interpret air-water-CD partitioning data. Our results show that HOP CD-water partition coefficients decrease linearly with increasing temperature. Adsorption isotherms of TCE to the granular activated carbon (GAC), Norit C GRAN, were determined for aqueous solutions containing a range of CD concentrations (0, 20, 50, 100 g L-1). The adsorption coefficient and constant of apparent and rescaled Freundlich isotherms was determined by the nonlinear regression of versus total aqueous concentration and free water phase concentration,respectively. Our results showed that in aqueous CD solutions, the adsorption to GAC decreased with increasing CD concentration due to the interaction of TCE with CD in the aqueous phase. A linear relationship was derived with the linear coefficient of 0.999. Breakthrough curves of single solute, TCE were obtained over a range of flow velocities (1-10 ml∙min-1) and HPCD concentrations (0, 20, and 50 g∙L-1). Relationships between the pore velocities and two-site non-equilibrium parameters obtained from CXTFIT program were illustrated for this specific adsorption. Comparison of original breakthrough curve under different CD concentrations to the solubility-enhancement-rescaled ones showed (1) all 3 curves exhibited similar scaled times at which they reach 50% of the input concentration and (2) cyclodextrin increased the time needed for TCE to reach equilibration between GAC and liquid phases. TCE at higher flow rate had insufficient time to interact with GAC such that non-equilibrium processes were more significant at higher flow rate

Chemical analysis of extracts from Port-Orford cedar wood and bark

This study investigated a Soxhlet extract procedure to separate chemical components in the wood and bark of Port-Orford cedar (POC) (Chamaecyparis lawsoniana). The bio-activities, antioxidant properties, and decay resistance were evaluated. The heartwood extracts were analyzed by gas chromatography-mass spectrometry (GC-MS). Three vitro assays including (1) 1, 1-diphenyl-2-picrylhydrazyl hydrate (DPPH• ) radical scavenging assay, (2) 2,2-azinobis ( 3-ethylbenzothiszoline-6-sulfonic acid) diammonium salt (ABTS) radical cation scavenging ability assay, and (3) metal chelating activity assay were carried out to evaluate the antioxidant activity. The total phenol content of the extracts was determined by the Folin-Ciocalteu method and expressed as Gallic Acid Equivalent (GAE). The results showed that the methanol extracts of the heartwood and the sapwood contained moderate radical scavenging activities, and the inner bark and outer bark extracts showed the most activities. The sapwood extracts demonstrated the strongest chelating metal capability. Among the four partitions of POC bark, the n-Butanol extracts (n-Bu) showed the highest inhibition effect on ABTS+• and the highest amount of total phenolic content, followed by ethyl acetate extracts (EA), water soluble components (Wa) and n-hexane extracts (n-He) subtractions. The correlation suggested that phenolic compounds are likely to contribute to the radical scavenging activity of the methanol extracts. There were three major components found in hexane extracts from the heartwood of POC, which were τ-cadinol, azulene, and τ–muurolol. Hexadecadinoic acid was found in ethyl acetate extracts. Both the n-hexane and ethyl acetate extracts of the heartwood of POC had excellent growth inhibitory effects on white- and brown-rot fungi. The n-hexane extracts showed a higher antifungal index in this assay system, which was significantly higher than the ethyl acetate extracts