Cobalt-Catalyzed Green Cross-Dehydrogenative C(sp<Superscript>2</Superscript>)-H/P-H Coupling Reactions

Joined electrolysis of arenes (benzene or coumarin derivatives) and diethyl-H-phosphonate (EtO)₂P(O)H in the presence of [CoCl₂(bpy)] catalyst (5%) in an ethanol-aqueous solution in reductive conditions allows obtaining the desired products in a single step by aromatic C–H bonds phosphonation with yields up to 70%. The only by-product is hydrogen; the reaction proceeds at room temperature and does not require specially added reducing agents and oxidants or other initiators. Radical mechanism has been confirmed for the catalytic reaction proceeding via bicobalt phosphonates with Co–P bond, the structure of which also has been identified.     

Dynamic graph summarization: a tensor decomposition approach

Due to the scale and complexity of todays’ social networks, it becomes infeasible to mine them with traditional approaches. A possible solution to reduce such scale and complexity is to produce a compact (lossy) version of the network that represents its major properties. This task is known as graph summarization, which is the subject of this research. Our focus is on time-evolving graphs, a more complex scenario where the dynamics of the network also should be taken into account. We address this problem using tensor decomposition, which enables us to capture the multi-way structure of the time-evolving network. This property is unique and is impossible to obtain with other approaches such as matrix factorization. Experimental evaluation on five real world networks implies promising results demonstrating that tensor decomposition is quite useful for summarizing dynamic networks.     

SECOL: a semantic environment based on social media to support organisational learning

Organisational learning (OL) helps companies to significantly improve their processes through the reuse of experiences, making knowledge accessible to the whole organisation. However, establishing learning in software development companies is not a trivial task, since it is an area in which processes and knowledge are usually hidden inside the employees’ mind. Generally, employees prefer to look for knowledge via Internet search engines rather than using the knowledge produced inside the company. Hence, we explored how better organising content produced within the company may minimise this problem. We investigated how a semantic collaborative environment, titled semantic collaborative environment for organisational learning (SECOL), based on social software, learning objects (LOs), and units of learning (UL) may assist to improve OL for software development companies. We defined an approach to generate LOs and UL from social software’s content used by companies. The environment was implemented based on ontologies in order to represent and organise acquired knowledge. Furthermore, an experiment was conducted using qualitative data analysis. The results indicated that the use of the environment is appropriate to improve OL in software development teams and the use of SECOL is efficient, particularly in order to acquire new knowledge, assisting the promotion of the use of organisational patterns and minimising repeated solutions.     

Hierarchical model reduction for incompressible fluids in pipes

Hierarchical model reduction is intended to solve efficiently partial differential equations in domains with a geometrically dominant direction. In many engineering applications, these problems are often reduced to 1‐dimensional differential systems. This guarantees computational efficiency yet dumps local accuracy as nonaxial dynamics are dropped. Hierarchical model reduction recovers the secondary components of the dynamics of interest with a combination of different discretization techniques, following up a natural separation of variables. The dominant direction is generally solved by the finite element method or isogeometric analysis to guarantee flexibility, while the transverse components are solved by spectral methods, to guarantee a small number of degrees of freedom. By judiciously selecting the number of transverse modes, the method has been proven to improve significantly the accuracy of purely 1‐dimensional solvers, with great computational efficiency. A Cartesian framework has been used so far both in slab domains and cylindrical pipes (including arteries) mapped to Cartesian reference domains. In this paper, we investigate the alternative use of a polar coordinates system for the transverse dynamics in circular or elliptical pipes. This seems a natural choice for applications like computational hemodynamics. In spite of this, the selection of a basis function set for the transverse dynamics is troublesome. As pointed out in the literature—even for simple elliptical problems—there is no “best” basis available. In this paper, we perform an extensive investigation of hierarchical model reduction in polar coordinates to discuss different possible choices for the transverse basis, pointing out pros and cons of the polar coordinate system.     

Influences of monomer self‐association on the radical solution homopolymerization of N‐[3‐(dimethylamino)propyl](meth)acrylamide

The specific dependencies of the initial reduced polymerization rate on the initial monomer concentration were introduced for the radical homopolymerization of N‐[3‐(dimethylamino)propyl]acrylamide (DMAPA) and N‐[3‐(dimethylamino)propyl]methacrylamide (DMAPMA) in toluene, DMF, and water at 60 °С. The degree of the monomer self‐association and the ratio of the amides constituting various types of associates were evaluated using FT‐IR spectroscopy and computer simulation for the solutions of DMAPA and DMAPMA in toluene with different monomer concentrations. The hypothesis linking the type of predominant pre‐reaction monomer assemblies and the revealed concentration effects was proposed for the homopolymerization of aminoamide monomers and explaining unconventional experimental data. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44412.     

Chromium adsorption on surface activated biochar made from tannery liming sludge: A waste-to-wealth approach

In a beamhouse, liming plays a key role in the removal of hair/wool and epidermis, but problems are created when waste liming sludge is discharged to the environment. The treatment of tannery wastewater is another major challenge to the industry. In this study, thermally-activated biochars derived from liming sludge were studied for their effective adsorption of chromium (Cr) from the tannery wastewater. The thermally activated biochars (B500, B550, B600, and B650) were prepared at different temperatures from the liming sludge. Their characteristics before and after the treatment were investigated using Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller, and scanning electron microscopy analyses. The related functional groups (C–H, O–H, C–N, and =C–O) and chromium adsorption capacity were determined according to the surface morphology, element contents (C, O, Ca, Na, Al, Mg, and Si), surface area (5.8–9.2 m²/g), pore size (5.22–5.53 nm), and particle size (652–1 034 nm) of the experimental biochars. The biochar originated at 600°C from the tannery liming sludge (B600) had a greater surface area with a chromium adsorption capacity of 99.8% in comparison to B500, B550, and B650 biochars. This study developed an innovative way of utilizing liming sludge waste to minimize the pollution load and wastewater treatment cost in the tannery industry.     

Orientation-Matching Minimization for Image Denoising and Inpainting

In this paper, we propose an orientation-matching functional minimization for image denoising and image inpainting. Following the two-step TV-Stokes algorithm (Rahman et al. in Scale space and variational methods in computer vision, pp. 473–482, Springer, Heidelberg, 2007; Tai et al. in Image processing based on partial differential equations, pp. 3–22, Springer, Heidelberg, 2006; Bertalmio et al. in Proc. conf. comp. vision pattern rec., pp. 355–362, 2001), a regularized tangential vector field with zero divergence condition is first obtained. Then a novel approach to reconstruct the image is proposed. Instead of finding an image that fits the regularized normal direction from the first step, we propose to minimize an orientation matching cost measuring the alignment between the image gradient and the regularized normal direction. This functional yields a new nonlinear partial differential equation (PDE) for reconstructing denoised and inpainted images. The equation has an adaptive diffusivity depending on the orientation of the regularized normal vector field, providing reconstructed images which have sharp edges and smooth regions. The additive operator splitting (AOS) scheme is used for discretizing Euler-Lagrange equations. We present the results of various numerical experiments that illustrate the improvements obtained with the new functional.