Solvent effects on phenolic contents and biological activities of the halophyte Limoniastrum monopetalum leaves

Limoniastrum monopetalum is a traditional medicinal species which leaf infusion exhibits antidysenteric properties against infectious diseases. In this study, ten kinds of leaf extracts were used to examine the effect of extraction solvent system with varying polarities on polyphenol contents and DPPH scavenging activity. Then the superoxide scavenging activity and the reducing power of the most promising solvent extracts were evaluated too. Moreover, the efficiency of the best leaf extract has been investigated against pathogenic bacteria and yeast. Eventually leaf extract was hydrolyzed by acid and the phenolics identified by RP-HPLC. Results showed that phenolic contents and antioxidant activities varied considerably as function of solvent polarity. Leaf extract using pure methanol showed the highest polyphenol content (15.85 mg GAE/g DW). Moreover, antiradical capacities against DPPH and superoxide, and reducing power were maxima in acetone/water (8:2) of leaf extract. However, the latter showed a slight antimicrobial activity against human pathogen strains such as Staphylococcus aureus, Micrococcus luteus and Candida holmii. The HPLC analysis revealed several phenolic compounds in L. monopetalum leaf including vanillic and gallic acids as major phenolics. Our findings identified the appropriate solvent for extracting halophyte phenolics which might provide a rich and novel source of natural antioxidants as food additives replacing synthetic ones in food industry.     

Characterization of waterproof-covering mortars on Ottoman monuments of “Ghar El Melh” (Tunisia)

This study is devoted to the characterization of two historic waterproof-coating mortars taken from the ottomans monuments of “Ghar El Melh” in, northeast Tunisia. The first waterproof mortar was recovered from the aqueduct channel, which was used to supply boats with water. The second type came from the terrace cupola of “Sidi Ali El Mekki” fortress. To characterize each mortar, physical, mineralogical, and chemical analyses were performed. These revealed that the two samples were mainly made of air-hardening lime mixed with pozzolanic additions. The binder/aggregate ratio was 0.6 for the aqueduct coating and 0.3 for the cupola. The relative presence of gypsum in the mortar of the aqueduct indicated its sulfatic alteration, but the two coatings were free of ettringite. Although these were in permanent contact with corrosive conditions, the two waterproof coatings showed good durability.     

Comparison between three optimization methods for the minimization of maximum bending load and springback in wiping die bending obtained by an experimental approach

The sheet metal bending process is widely used in the automotive industries, and it is actually one of the most important manufacturing processes. The robustness and the reliability of the bending operation, like many other forming operations, depend of several parameters (geometry, material, and process). In this paper, the die radius and the clearance between the punch and the sheet are optimised in order to reduce the maximum bending load and the springback. Two optimization problems are formulated, and three optimization procedures based on the response surface method are proposed and used to find the optimum solutions. Global and local approximations are used to replace the initial optimization problem, which is implicit by an explicit problem, and the optimum is localised using two algorithms: a sequential quadratic programming and an evolution strategies. The objective functions are evaluated experimentally into a limited points number, which are defined using a design of experiments technique. Good results are obtained from the three optimization procedures. The ability of each technique to find the optimal solution is evaluated, and the results show a good agreement between those three methods.     

Fermentation of date palm juice by curdlan gum production from Rhizobium radiobacter ATCC 6466™: Purification, rheological and physico-chemical characterization

The present study was undertaken to investigate the possibility of using date palm juice byproducts for curdlan production by Rhizobium radiobacter ATCC 6466™ in batch experiments. A number of operational parameters, namely pH value, temperature range, inoculum ratio, agitation speed, carbon concentration, nitrogen source, and fermentation time, were investigated in terms of their optimal values for as well as individual and synergistic effects on curdlan production. The findings indicated that the strain exhibited a high ability to use the natural substrate under investigation. A curdlan production yield of 22.83 g/l was obtained in 500-ml agitated flasks (50 ml) when the strain was cultivated in the optimal medium (pH, 7; ammonium sulphate concentration, 2 g/l; date glucose juice concentration, 120 g/l) operating at 30 °C with an inoculum ratio of 5 ml/100 ml, an agitation speed of 180 rpm, and a fermentation period of 51 h. The purified date byproducts-curdlan (DBP-curdlan) had a molecular weight of 180 kDa, a linear structure composed exclusively of β-(1,3)-glucosidic linkages, a melting temperature (T_m) and glass transition temperature (T_g) of 1.24 and −3.55 °C, respectively. The average measured heights of its molecules were noted to fluctuate between 14.1 ± 0.07 and 211.73 ± 0.6 μm.     

碳纤维增强复合材料加固钢板的边界元分析

采用边界元分析对碳纤维增强复合材料加固钢板的疲劳性能进行扩展研究。采用BEASY软件计算应力强度因子、裂缝扩展和疲劳周期。应用面单元模拟组合增强片和带裂缝的钢板,将粘结层作为连接增强片和钢板的界面单元。数值模拟结果与试验结果具有一致性,从而验证了本文方法的有效性。采用边界元方法,对影响应力强度因子和疲劳寿命的因素进行评估,这些因素包括粘结长度、粘结宽度、增强片配置、碳纤维增强复合材料的层数组合增强片模量、粘结组合模量。     

Lyapunov–Sylvester computational method for numerical solutions of a mixed cubic-superlinear Schrödinger system

Engineering with Computers - An upwind skewed radial basis function (USRBF)-based solution scheme is presented for stabilized solutions of convection-dominated problems over meshfree nodes. The...     

Site-selective spectroscopy of Eu-doped orthorhombic lanthanum and monoclinic yttrium polyphosphates

In order to study the influence in the change of the coordination environment of the cationic sites on the luminescent properties of rare-earth ions doping polyphosphates Ln(PO₃)₃ (Ln = La, Y) with two different structures, the time-resolved luminescence of the Eu³⁺ ion, used as structural probe, is reported. La(PO₃)₃ has an orthorhombic structure in which only one position with eight coordination is available for the cation, while Y(PO₃)₃ adopts the Yb(PO₃)₃ structure in which four slightly different octahedral sites are available for the trivalent rare-earth ion. Site-selective excitation of the ⁵D₀ level was performed and luminescence decay times of each Eu³⁺ site were measured at 77 K. The spectroscopic results are discussed and correlated with the structural data.     

An Evaluation of RetinaNet on Indoor Object Detection for Blind and Visually Impaired Persons Assistance Navigation

Neural Processing Letters - Indoor object detection presents a computer vision task that deals with the detection of specific indoor classes. This task attracts a lot of attention, especially in...     

Covariance-guided landmine detection and discrimination using ground-penetrating radar data

Ground penetrating Radar (GPR) can detect and deliver the response signal from any buried kind of object like plastic or metallic landmines, stones, and wood sticks. It delivers three kinds of data: Ascan, Bscan, and Cscan. However, it cannot discriminate between landmines and inoffensive objects or ‘clutter.’ One-class classification is an alternative to detect landmines, especially, as landmines features data are unbalanced. In this article, we investigate the effectiveness of the Covariance-guided One-Class Support Vector Machine (COSVM) to detect, discriminate, and locate landmines efficiently. In fact, compared to existing one-class classifiers, the COSVM has the advantage of emphasizing low variance directions. Moreover, we will compare the one-class classification to multiclass classification to tease out the advantage of the former over the latter as data are unbalanced. Our method consists of extracting Ascan GPR data. Extracted features are used as an input for COSVM to discriminate between landmines and clutter. We provide an extensive evaluation of our detection method compared to other methods based on relevant state of the art one-class and multiclass classifiers, on the well-known MACADAM database. Our experimental results show clearly the superiority of using COSVM in landmine detection and localization.     

Tomographic Reconstruction of 3D Objects Using Marked Point Process Framework

For reconstructing sparse volumes of 3D objects from projection images taken from different viewing directions, several volumetric reconstruction techniques are available. Most popular volume reconstruction methods are algebraic algorithms (e.g. the multiplicative algebraic reconstruction technique, MART). These methods which belong to voxel-oriented class allow volume to be reconstructed by computing each voxel intensity. A new class of tomographic reconstruction methods, called “object-oriented” approach, has recently emerged and was used in the Tomographic Particle Image Velocimetry technique (Tomo-PIV). In this paper, we propose an object-oriented approach, called Iterative Object Detection—Object Volume Reconstruction based on Marked Point Process (IOD-OVRMPP), to reconstruct the volume of 3D objects from projection images of 2D objects. Our approach allows the problem to be solved in a parsimonious way by minimizing an energy function based on a least squares criterion. Each object belonging to 2D or 3D space is identified by its continuous position and a set of features (marks). In order to optimize the population of objects, we use a simulated annealing algorithm which provides a “Maximum A Posteriori” estimation. To test our approach, we apply it to the field of Tomo-PIV where the volume reconstruction process is one of the most important steps in the analysis of volumetric flow. Finally, using synthetic data, we show that the proposed approach is able to reconstruct densely seeded flows.