Databases deepen the Web

The Web has become the preferred medium for many database applications, such as e-commerce and digital libraries. These applications store information in huge databases that users access, query, and update through the Web. Database-driven Web sites have their own interfaces and access forms for creating HTML pages on the fly. Web database technologies define the way that these forms can connect to and retrieve data from database servers. The number of database-driven Web sites is increasing exponentially, and each site is creating pages dynamically-pages that are hard for traditional search engines to reach. Such search engines crawl and index static HTML pages; they do not send queries to Web databases. The information hidden inside Web databases is called the "deep Web" in contrast to the "surface Web" that traditional search engines access easily. We expect deep Web search engines and technologies to improve rapidly and to dramatically affect how the Web is used by providing easy access to many more information resources.     

Biocompatible graphene-embedded PCL/PGS-based nanofibrous scaffolds: A potential application for cardiac tissue regeneration

Research in the field of tissue engineering, especially heart tissue engineering, is growing rapidly. Herein, the morphological, chemical, mechanical and biological properties of poly (caprolactone) (PCL)/poly (glycerol sebacate) (PGS) and PCL/PGS/graphene nanofibrous scaffolds are investigated. Initially, PGS pre-polymer is synthesized and characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopies. Then, in order to use the benefits of PGS, this polymer is mixed with PCL. Blending PGS with PCL resulted in the enhancement of ultimate elongation and reduction in the elastic modulus due to the intrinsic properties of PGS. The hydrophobicity of PCL nanofibers is reduced by adding PGS as hydrophilic polymer (105 ± 3° vs. 44 ± 2°). Also, the addition of graphene to the blend nanofibers is balanced the hydrophilicity. Degradation rate of pure PCL nanofibers is very slow but it is increased in the presence of PGS. All nanofibrous scaffolds are biocompatible and non-toxic. The highest cell adhesion (covered area = 0.916 ± 0.032) and biocompatibility (98.79 ± 1%) are related to PCL/PGS loaded with 1% wt of graphene (PCL/PGS/graphene ₁). Thus, this sample can be a good candidate for further examinations of cardiac tissue engineering.     

Restructuring Metal–Organic Frameworks to Nanoscale Bismuth Electrocatalysts for Highly Active and Selective CO2 Reduction to Formate

Recently, a large number of nanostructured metal‐containing materials have been developed for the electrochemical CO₂ reduction reaction (eCO₂RR). However, it remains a challenge to achieve high activity and selectivity with respect to the metal load due to the limited concentration of surface metal atoms. Here, it is reported that the bismuth‐based metal–organic framework Bi(1,3,5‐tris(4‐carboxyphenyl)benzene), herein denoted Bi(btb), works as a precatalyst and undergoes a structural rearrangement at reducing potentials to form highly active and selective catalytic Bi‐based nanoparticles dispersed in a porous organic matrix. The structural change is investigated by electron microscopy, X‐ray diffraction, total scattering, and spectroscopic techniques. Due to the periodic arrangement of Bi cations in highly porous Bi(btb), the in situ formed Bi nanoparticles are well‐dispersed and hence highly exposed for surface catalytic reactions. As a result, high selectivity over a broad potential range in the eCO₂RR toward formate production with a Faradaic efficiency up to 95(3)% is achieved. Moreover, a large current density with respect to the Bi load, i.e., a mass activity, up to 261(13) A g^?1 is achieved, thereby outperforming most other nanostructured Bi materials.     

Spatially Enhanced Bags of Visual Words Representation to Improve Traffic Signs Recognition

Traffic signs play a very vital role in safe driving and in avoiding accidents by informing the driver about the speed limits or possible dangers such as icy roads, imminent road works or pedestrian crossings. Considering the processing time and classification accuracy as a whole, a novel approach for visual words construction was presented, which takes the spatial information of keypoints into account in order to enhance the quality of visual words generated from extracted keypoints using the distance and angle information in the Bags of Visual Words (BoVW) representation. In this paper, we proposed a new computationally efficient method to model global spatial distribution of visual words by taking into consideration the spatial relationships of its visual words. In the first step, the region of interest is extracted using a scanning window with a Haar cascade detector and an AdaBoost classifier to reduce the computational region in the hypothesis generation step. Second, the regions are represented with BoVW and spatial information for classification. Experimental results show that the suggested method could reach comparable performance of the state-of-the-art approaches with less computational complexity and shorter training time. It clearly demonstrates the complementarity of the additional relative spatial information provided by our approach to improve accuracy while maintaining short retrieval time, and can obtain a better traffic sign recognition accuracy than the methods based on the traditional BoVW model.     

Characteristics and evaluation of synthetic 13X zeolite from Yunnan’s natural halloysite

High purity microporous 13X zeolitic materials with octahedral microstructure were successfully synthesized by using Yunnan’s natural halloysite as silica and aluminum sources through hydrothermal method in alkaline media. The effects of various factors such as the molar ratio of SiO₂/Al₂O₃, alkalinity, crystallization time and crystallization temperature were investigated. In addition, the characteristics of its structure and porosity were studied. The optimum synthesis conditions were SiO₂/Al₂O₃ molar ratio of 4.3, NaOH solution concentration of 2 mol/L, aging time at room temperature 12 h and crystallization temperature of 100 °C/8 h. The optimum 13X zeolitic materials were fully characterized by chemical analysis, X-ray diffraction, field emission scanning electron microscopy, thermogravimetry and N₂ adsorption–desorption. The as-synthesized 13X zeolitic products exhibited high thermal stability and Langmuir surface area of up to 726 m²/g, value much higher than elsewhere reported.