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Users are members of communities on social networks. Users’ interested topics keep changing, resulting in the change of their communities’ interested topics as well. Level, period of time, and interested topics represent features of a community which (i) change upon preferences of each user on social networks for making friends or being interested in topics (based on message content); (ii) are formed or change from online groups of friends or the suggestions to make friends. Hence, the link of users in communities can be viewed as a network of users by their features in social network communities. In this paper, the author studies and proposes a new model for discovering communities using Temporal-Author-Recipient-Topic (TART) model combined with Kohonen neural networks to discover communities of users with the same interested topics over different periods of time. The research goal is achieved through testing models on two Vietnamese datasets (collected from social networks at universities and online newspapers).

Le but de ce travail consiste faire une proposition de solution afin d’optimiser le système de balisage de Decathlon. Pour ce faire, l’objectif principal sera de trouver une réponse à la question de recherche suivante : « Quel système de balisage pour l’affichage du prix des produits et des rayons offrira la meilleure expérience d’achat au client tout en étant pratique et écologique ? ».

The studies by Davis B, Summers M (2015), and E. Dale (1969) showed that learners can remember 20% of what they listen, 30% of what they see and as high as 90% of what they simulate. While training institutions have not had conditions to coordinate with enterprises to train together with practice, simulation system or virtual reality can create the second perfect scenario for learners to interact with different people in and out of that environment. Based on Davis B, Summers M (2015), E. Dale (1969), experience in using a variety of learning and teaching methods in e-commerce major and working with enterprises, the authors propose the establishment of simulated electronic markets for effectively deploying the “learning by doing” method as well as for the research and application of e-commerce models and solutions via simulation systems. The results, discussions and proposal for simulated electronic markets are summarized in this paper.

Outbreaks of disease in humans and animals and their crossspecies transmission pose a significant risk to the health of the population, poultry, fisheries and livestock, and could influence business, economy, tourism, and reputation of a country...

Nowadays, supermarkets or retail chains are increasingly interested in how to increase productivity at their stores. The problem here is that prices, promotions and product information updates need to be immediate. Building an electronic signage solution that uses interactive mobile Internet of Things (IoT) technology including technology for Electronic Commerce to Opticon Electronic signage solutions (ESL) devices allows stores, supermarkets to change product prices in real time and launch promotional campaigns at Any time or place as desired. The system has been widely deployed in Vietnam market. ESL helps eliminate traditional labeling, labor saving, and other costs associated with price changes and product information, especially through mobile devices, users can easily change electronic prices quickly and conveniently. The solution of this article has been posted on http://opticon.vn.

The development of new advanced nanostructures based on the hybridization of different carbon nanomaterials to obtain enhanced performance of energy storage devices has attracted considerable attention. Herein, a hierarchical nanostructure of carbon nanotubes supported electrospun carbon nanofiber networks (CNTs@CNFs) was successfully fabricated by using two facile techniques: – electrospinning and chemical vapor deposition (CVD). Such CNTs@CNFs hybrid showed the uniform and high density of CNTs directly grown on the surface of carbon nanofiber networks, leading to the formation of a hierarchical nanostructure with a large surface area and highly porous characteristics. The enhanced interactions between the CNTs and the CNFs networks were found to improve the electrical conductivity and electrochemical stability of the material. Owing to its unique nanoarchitectures and physicochemical properties, the CNTs@CNFs hybrid was demonstrated to be a potential electrode material for an electrochemical capacitor, in which a high specific capacitance of 464.2 F g−1 at 0.5 A g−1 and long-term stability with 97% retention after 10,000 repeated charge–discharge cycles were achieved. The obtained results suggest that the present CNTs@CNFs hybrid is a promising candidate for an electrochemical capacitor in energy storage technologies.

In this study, a novel hierarchical porous network of Pt51Pd49 alloy-integrated graphene nanosheet as active catalyst towards ethanol oxidation was fabricated using electroless deposition followed by chemical vapour deposition for the first time. Such materials were obtained as a three-dimensional continuous and non-order porous architecture with good dispersion and uniformity of the ultrasmall Pt51Pd49 nanoalloy particles (∼3 nm) within the graphene nanosheets. As an electrocatalyst, it exhibited excellent catalytic behaviour towards ethanol oxidation with superior conversion, long-term stability and better tolerance towards intermediate's poisoning effect, as compared to commercial Pt black product. The results were associated with the enhanced electroactive surface area and mass transfer possibility of the catalyst due to the formation of an unique porous nanostructure for Pt51Pd49 alloys. In addition, the coating effect of graphene nanosheets over Pt51Pd49 alloy nanoparticles avoided aggregation and dissolution, possibly allowing full utilization of the active sites from all nanoparticles, and thus efficiently improving charge transfer ability and working stability of the catalyst. Owning high quality, good electrochemical performance, and ease of synthesis, the as-synthesized catalyst opens an interesting nanoarchitecture class for efficiently catalyzing ethanol oxidation in fuel cells.

Development of highly efficient adsorbent materials for the wastewater treatment is an excellent, cheap, environmental friendly and sustainable approach. Herein, a novel cotton flower-like hierarchically porous boron nitride (BN) structure was successfully synthesized by pyrolizing a boric acid/melamine mixture at 1100 °C in a controlled flow rate ratio of N 2 /H 2 . The obtained porous BN material with a large specific surface area (SSA) of 1140 m 2 g −1 exhibited high selectivity, fast adsorption rate (∼96% for methylene blue (MB) after 20 min and ∼80% for rhodamine B (RhB) after 10 min) and high adsorption capacities (∼471.2 and 313.4 mg⋅g −1 for MB and RhB, respectively). The excellent selectivity of porous BN material towards dyes adsorption was confirmed from a mixed solution of dye and inorganic salts. In addition, porous BN material remain sustained without losing its adsorption activity even after 10 cycles and exhibited easy regeneration and good reusability which were achieved by a simple heating process. The obtained results indicated that the present porous BN material is a potential candidate for the removal of organic pollutants in water treatment applications.

Nickel-palladium alloy nanoparticles over graphene nanosheets (NiPd alloy NPs/GNS) are synthesized using ammonia-hydrazine method via a surfactant-free hydrothermal process. NiPd alloy NPs/GNS represent a new class of electrocatalyst with enhanced activity and stability for formic acid and ethanol oxidation reactions. The as-prepared catalysts are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), STEM-elemental mapping, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Cyclic voltammetry (CV) and chronoamperometry (CA) studies reveal that bimetallic alloy nanoparticles exhibit higher catalytic activity than monometallic catalysts toward electro-oxidation reactions. The higher activity is mainly attributed to the strong assembly of bimetallic NiPd alloy NPs over graphene sheets. The novel NiPd alloy NPs/GNS catalysts provide a new strategy for superior electro-catalytic performance in next-generation fuel cells.