Recurrent Poisson Factorization for Temporal Recommendation

Poisson factorization is a probabilistic model of users and items for recommendation systems, where the so-called implicit consumer data is modeled by a factorized Poisson distribution. There are many variants of Poisson factorization methods who show state-of-the-art performance on real-world recommendation tasks. However, most of them do not explicitly take into account the temporal behavior and the recurrent activities of users which is essential to recommend the right item to the right user at the right time. In this paper, we introduce Recurrent Poisson Factorization (RPF) framework that generalizes the classical PF methods by utilizing a Poisson process for modeling the implicit feedback. RPF treats time as a natural constituent of the model and brings to the table a rich family of time-sensitive factorization models. To elaborate, we instantiate several variants of RPF who are capable of handling dynamic user preferences and item specification (DRPF), modeling the social-aspect of product adoption (SRPF), and capturing the consumption heterogeneity among users and items (HRPF). We also develop a variational algorithm for approximate posterior inference that scales up to massive data sets. Furthermore, we demonstrate RPF's superior performance over many state-of-the-art methods on synthetic dataset, and large scale real-world datasets on music streaming logs, and user-item interactions in M-Commerce platforms.Comment: Submitted to KDD 2017 | Halifax, Nova Scotia - Canada - sigkdd, Codes are available at https://github.com/AHosseini/RP

Synthesis and gas-sensing properties of nano- and meso-porous MoO3-doped SnO2

Nano- and meso-porous SnO2 powders doped with and without 1-10 wt% MoO3 have been synthesized by an ultrasonic spray-pyrolysis method employing a precursor aqueous solution containing tin (IV) chloride pentahydrate (SnCl4·5H2O), ammonium heptamolybdate and polymethylmethacrylate (PMMA) microspheres as a template, and the effects of MoO3-doping and the addition of PMMA microspheres on the structural, morphological and gas-sensing properties of SnO2 were investigated in this study. It is confirmed that control of the amounts of PMMA microspheres in the precursor solution was effective in realizing well-developed nano- and meso-porous structures of SnO2 by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and the measurement of specific surface area and pore size distribution using a N2 adsorption isotherm. Gas-sensing properties of their thick films (about 50 μm thick), which were fabricated by screen-printing to various gases (NO2, C2H5OH and H2) were tested in ambient air. The doped thick films showed a high response and selectivity to 5 ppm NO2 gas in the case of 10 wt% MoO3-doping in both nano- and meso-porous structures of SnO2. We observed that the presence of Mo species in SnO2 lattice can improve the sensor response and selectivity towards NO2 gas. The effect of the MoO3-doping on the sensing characteristics of these films towards NO2 was discussed

IL-23 and IL-27 gene expression in three breast cancer cell lines and metastatic and non-metastatic lymph nodes in breast cancer patients

Introduction: There is a great need to identify prognostic and diagnostic cancer bio-markers which can be applied for vaccine and immunotherapy development. The aim of this study was to determine gene expression of IL-23 and IL-27 in two groups: lymph nodes of breast cancer patients and three cell lines. Materials and Methods: IL-23 and IL-27 mRNA transcript were investigated in 10 lymph node samples (consisting of 5 metastasis and 5 non metastasis ones) and three cell lines (including of SKBR3, MDA-MB-468 and MCF7) by quantitative real time PCR (Q-PCR) procedure using designed primers, Master Mix reaction containing SYBER green and β actin housekeeping gene. Results: Data showed no significant differences in IL-23 and IL-27 mRNA gene expressions among metastatic lymph node and non-metastatatic ones. Also, we did not find any significant differences in IL-23 and IL-27 mRNA expressions in cancer cell lines. Conclusions: Our findings indicate that breast cancer microenvironment has no effect on inflammation via either IL-23 gene expression or Il-27

Efficient synergistic chemical fixation of CO2 by simple metal-free organocatalysts : Mechanistic and kinetic insights

Background: Carbon dioxide is a versatile, non-toxic, and renewable C1 building block source to produce valuable chemicals such as cyclic carbonates. The purpose of this research is development of efficient, metal free and affordable catalysts for cycloaddition reaction of CO2 with epoxides at mild conditions. Methods: In the present work, a group of novel bifunctional organocatalysts consisting of different hydrogen bond donors (HBDs) and halogen ion is simply synthesized. Under the optimized conditions, the reaction is kinetically and thermodynamically studied. Additionally, the catalytic active species are determined, and a mechanism is proposed with the help of electrospray-ionization time-of -flight mass spectrometry (ESITOF MS). Significant findings: The most active catalytic system is obtained by chemically interaction of 3-bromopropionic acid (BPA) with DMF at 80 degrees C (BPA-DMF). An excellent product yield of 98% and a high TOF value are obtained with 0.99 mol% of BPA-DMF, which is attributed to the synergistic effects of carboxyl functional groups and halide ions. The activation energy was found to be 50.75 kJ/mol. The positive value of Gibbs free activation energy (DGt) and negative value of activation entropy (DSt) confirm a non-spontaneous, endergonic and kinetically controlled reaction. (c) 2021 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Peer reviewe

Highly dispersed atomic layer deposited CrOx on SiO2 catalyst with enhanced yield of propylene for CO2 –mediated oxidative dehydrogenation of propane

The increasing worldwide demand for propylene and the necessity of CO2 mitigation attracted the attention of scientists to focus on CO2-oxidative dehydrogenation of propane (CO2-ODHP). In this regard, CrOx/SiO2 catalyst is an important and conventional option. Herein, we studied the atomic layer deposition (ALD) of CrOx on silica to increase the propylene production by increasing the dispersion of the catalyst. For ALD synthesis of CrOx/SiO2 catalyst, Cr(acac)3 and synthetic air were used as metal precursor and oxidant. The catalysts were examined in the CO2-ODHP reaction and their characteristics were compared to their impregnation counterparts using UV–Vis DRS, Raman, XANES, HRTEM and STEM-EDS mapping, H2-TPR, NH3-TPD and TPO. The ALD catalysts have shown up to 2 times higher acidity and enhanced reducibility compared to the impregnation catalysts. The presence of mainly Cr(VI) with a pre-edge peak at 5.994 keV in both series of catalysts was confirmed by XANES. UV–Vis DRS and Raman spectroscopy revealed the higher contents of active polymeric Cr(VI) species in the ALD ones. The dark field HRTEM and STEM-EDS mapping represented higher dispersion of chromium oxide particles in ALD catalysts. In CO2-ODHP, the ALD catalysts showed up to 18 and 15% promotion in propane conversion and propylene yield.Peer reviewe