BEM for transient 2D elastodynamics using multiquadric functions

A new boundary element model for transient dynamic analysis of 2D structures is presented. The dual reciprocity method (DRM) is reformulated for the 2D elastodynamics by using the multiquadric radial basis functions (MQ). The required kernels for displacement and traction particular solutions are derived. Some terms of these kernels are found to be singular; therefore, a new smoothing technique is proposed to solve this problem. Hence, the limiting values of relevant kernels are computed. The validity and strength of the proposed formulation are demonstrated throughout several numerical applications. It is proven from the results that the present formulation is more stable than the traditional DRM, which uses the conical (1 + R) function, especially in predicting results in the far time zone.     

Soil deformation and slip relative to grouser shape and spacing

The development of soil deformation patterns and failure status behind grousers in the production of drawbar pull is examined in relation to grouser shape, size, and spacing (between grousers). The kinds of deformations, slip conditions, and patterns of soil displacement can be usefully examined to provide the input required for optimizing track performance.     

Untargeted Phytochemical Profile,Antioxidant Capacity and Enzyme Inhibitory Activity of Cultivated and Wild Lupin Seeds from Tunisia

Lupin seeds can represent a valuable source of phenolics and other antioxidant compounds. In this work, a comprehensive analysis of the phytochemical profile was performed on seeds from three Lupinus species, including one cultivar (Lupinus albus) and two wild accessions (Lupinus cossentinii and Lupinus luteus), collected from the northern region of Tunisia. Untargeted metabolomic profiling allowed to identify 249 compounds, with a great abundance of phenolics and alkaloids. In this regard, the species L. cossentinii showed the highest phenolic content, being 6.54 mg/g DW, followed by L. luteus (1.60 mg/g DW) and L. albus (1.14 mg/g DW). The in vitro antioxidant capacity measured by the ABTS assay on seed extracts ranged from 4.67 to 17.58 mg trolox equivalents (TE)/g, recording the highest values for L. albus and the lowest for L. luteus. The DPPH radical scavenging activity ranged from 0.39 to 3.50 mg TE/g. FRAP values varied between 4.11 and 5.75 mg TE/g. CUPRAC values for lupin seeds ranged from 7.20 to 8.95 mg TE/g, recording the highest for L. cossentinii. The results of phosphomolybdenum assay and metal chelation showed similarity between the three species of Lupinus. The acetylcholinesterase (AChE) inhibition activity was detected in each methanolic extract analyzed with similar results. Regarding the butyrylcholinesterase (BChE) enzyme, it was weakly inhibited by the Lupinus extracts; in particular, the highest activity values were recorded for L. albus (1.74 mg GALAE/g). Overall, our results showed that L. cossentinii was the most abundant source of polyphenols, consisting mainly in tyrosol equivalents (5.82 mg/g DW). Finally, significant correlations were outlined between the phenolic compounds and the in vitro biological activity measured, particularly when considering flavones, phenolic acids and lower-molecular-weight phenolics.     

L~∞-Bounds of Solutions for Strongly Nonlinear Elliptic Problems with Two Lower Order Terms

In this work,we will prove the existence of bounded solutions in W_0~(1,p)(Ω)∩L~∞(Ω) for nonlinear elliptic equations-div(a(x,u,▽u))+g(x,u,▽u)+H(x,▽u) =f,where a,g and H are Caratheodory functions which satisfy some conditions,and the right hand side/belongs to W~(-1,q)(Ω).     

Cordierite-based refractory ceramics from natural halloysite and peridotite: Insights on technological properties

Cordierite-based ceramics were fabricated from Moroccan natural halloysite clay by using a simple and low-cost manufacturing method. To this end, peridotite and halloysite samples, collected from Beni Bousera and Melilla sites, Morocco, were used as raw materials for ceramics manufacturing. A starting mixture was prepared (76.08 wt% of clay and 23.92 wt% of peridotite), molded and heated to the desired temperature (1250, 1300 and 1350 °C) to fabricate cordierite ceramic specimens. Both raw materials (peridotite and halloysite) and final ceramics were analyzed using routine characterization techniques including chemical analysis by XRF, mineralogical analysis by XRD, thermogravimetric analysis, and morphological characteristics using scanning electron microscopy (SEM). The prepared ceramics were investigated regarding their mineralogical composition, thermal and technological properties, chemical resistance, and microstructural characteristics. Our results indicated that peridotite sample is mainly composed of silica (40.25 wt%) and magnesia (38.05 wt%) while halloysite is consisted essentially of silica (38.00 wt%) and alumina (34.13 wt%). This was confirmed by XRD, TG-DTA and FTIR analyses. The prepared ceramic specimens at different sintering temperatures (i.e., 1250, 1300 and 1350 °C) have regular cylindrical forms, displaying good ceramic properties. This is consolidated with the main technological tests including porosity (4.56–3.11%), bulk density (2.45–2.78 g/cm³), shrinkage (6.51–10.31%), indirect tensile strength (20.35–27.60 MPa), and low linear thermal expansion coefficient (3.05–2.18 × 10^?6/°C). Cordierite specimen prepared at 1350 °C provided the best ceramic sample with the highest technological properties, good chemical resistance and thermal properties. Thus, naturally abundant halloysite and peridotite deposits are potential candidates for cordierite-based ceramic manufacture. Therefore, the achieved results have provided cost-effective ceramic bricks with physical, thermal and mechanical properties that are favorable to be used as refractory bricks.     

The genus Machaerium (Fabaceae): taxonomy,phytochemistry, traditional uses and biological activities

Machaerium, in the family Fabaceae, predominantly is a genus of a Neotropical distribution of trees, shrubs, and lianas occurring from southern Mexico to Brazil and northern Argentina and as far as South America. Several Machaerium species are widely used in traditional medicine and are considered to have multiple medicinal properties. This review aims to provide up-to-date and comprehensive information on the taxonomy, phytochemistry, traditional uses and biological activities of plants in the genus Machaerium.     

New Synthesis of Pyrido[2,3-d] and [3,2-d]Oxazines

N-Hydroxyquinolinimide 1 reacts with each of aromatic amines, hydrazine hydrate and aromatic hydrocarbons to give arylcarbamoyl pyridines 2, pyrrolopyridines 3, pyridopyridazines 4 and pyridooxazinones 5 and 6. The heterocycles 5 and 6 can be transformed to the condensed systems, triazolopyridopyridazines 14 and 15 through series of reactions.