Adsorption of Cr(VI) on Stipa tenacissima L (Alfa): Characteristics,kinetics and thermodynamic studies

This study aims to remove ionic Cr(IV) from aqueous solution using Stipa tenacissima L as a biomass source. The Arabic name for the plant Stipa tenacissima L is HALFA (ALFA) ; it belongs to the category of biosorbents agro-industrial origin. Stipa tenacissima L is from the center of the province of Djelfa Algeria. This biomass was characterized by various analytical techniques such as scanning electron microscopy, energy dispersive spectroscopy and Fourier-transform infrared spectroscopy. In order to optimize the operating conditions for the determination of ions of Cr(VI), the initial concentration of Cr(VI) ions, temperature, pH of the solution and the solid/liquid ratio were individually studied. According to the results, a fix rate of about 90% was recorded. Optimum biosorption conditions were found to be pH ~1, C_o = 50 mg/L, R = 5 g/L and T = 296 K. It was found that biosorption of Cr(VI) ions onto biomass of Stipa tenacissima L was better suitable to Langmuir model. The correlation coefficients for the second-order kinetic model obtained were found to be 0.996 for all concentrations. These indicate that the biosorption system studied belongs to the second-order kinetic model. Thermodynamics parameters as enthalpy, entropy of system and free energy were evaluated, which confirms the feasibility of the process. An empirical modeling was performed by using a 2⁴ full factorial design, and the regression equation for adsorption chromium (VI) was determined from the data. The initial metal ion concentration has the most positive pronounced effect in increasing the chromium (VI) adsorption, whereas the pH and adsorbent dosage have the most negative effect on the process.     

Pediocin PA-1 production during repeated-cycle batch culture of immobilized Pediococcus acidilactici UL5 cells

Pediocin PA-1 production by Pediococcus acidilactici UL5 cells immobilized in kappa-carrageenan/locust bean gum gel beads was studied during repeated-cycle batch (RCB) culture with pH control in Man Rogosa and Sharpe (MRS) broth supplemented with 1% glucose and whey permeate (SWP) medium. The pediocin PA-1 production by free P. acidilactici cells pH-controlled batch culture has reached 2048 and 4096 AU ml(-1) after 11 and 12 h of incubation, with volumetric productivities of 187 and 342 AU ml(-1) h(-1) in SWP and MRS media, respectively. In RCB culture, immobilized cells reached a maximum concentration of 7.3+/-0.2 x 10(10) and 4.3+/-0.9 x 10(10) cfu g(-1) of beads in MRS and SWP media, respectively. The maximum pediocin PA-1 activity obtained during RCB fermentation was 4096 AU ml(-1); it was attained after only 0.75 and 2 h of incubation in MRS and SWP media, respectively. The corresponding volumetric productivities were 5461 and 2048 AU ml(-1) h(-1). Pediocin PA-1 production in the RCB culture was highly stable over 12 fermentation cycles carried out over 3 d in SWP media.     

Bioprospecting Antimicrobials from Lactiplantibacillus plantarum: Key Factors Underlying Its Probiotic Action

Lactiplantibacillus plantarum (L. plantarum) is a well-studied and versatile species of lactobacilli. It is found in several niches, including human mucosal surfaces, and it is largely employed in the food industry and boasts a millenary tradition of safe use, sharing a long-lasting relationship with humans. L. plantarum is generally recognised as safe and exhibits a strong probiotic character, so that several strains are commercialised as health-promoting supplements and functional food products. For these reasons, L. plantarum represents a valuable model to gain insight into the nature and mechanisms of antimicrobials as key factors underlying the probiotic action of health-promoting microbes. Probiotic antimicrobials can inhibit the growth of pathogens in the gut ensuring the intestinal homeostasis and contributing to the host health. Furthermore, they may be attractive alternatives to conventional antibiotics, holding potential in several biomedical applications. The aim of this review is to investigate the most relevant papers published in the last ten years, bioprospecting the antimicrobial activity of characterised probiotic L. plantarum strains. Specifically, it focuses on the different chemical nature, the action spectra and the mechanisms underlying the bioactivity of their antibacterial and antiviral agents. Emerging trends in postbiotics, some in vivo applications of L. plantarum antimicrobials, including strengths and limitations of their therapeutic potential, are addressed and discussed.     

Industrial fire simulation and uncertainty associated with the Emission Dispersion Model

The use of numerical modeling in the field of industrial fire accidentology has become common nowadays and this tendency is expected to increase with the development of performance simulation tools. Despite the constant development of fire modeling tools, the current state of the art is not yet able to accurately predict fire phenomena. This gap between the reality and simulations is probably due to the presence of some level of uncertainty, which may occur from the meteorological inputs, diffusion assumptions, plume dynamics, or emission production. To cope with the presence of uncertainties in the input data, we propose an uncertainty analysis enabling to avoid as much as possible bad decisions that may have a large impact in domains such as safety. In this study, we are interested in the uncertainty propagation related to NO₂ atmospheric dispersion resulting from a crude oil tank fire. Uncertainties were defined a priori for each of the following input parameters: wind speed, NO₂ emission rate, and viscosity and diffusivity coefficients. For that purpose, a Monte Carlo approach has been used. In order to evaluate the importance of the considered parameters on the NO₂ dispersion, new sensitivity indicator has been developed. The obtained results showed that the viscosity coefficient and the wind speed are the most significant input parameters with respect to NO₂ concentration near to the source of fire, while the wind speed and the initial concentration are the important parameters for distant areas.     

A consistent QoS routing strategy for video streaming services in SDN networks

The software‐defined networking (SDN) paradigm proposes to decouple the control plane (decision‐making process) and the data plane (packet forwarding) to overcome the limitations of traditional network infrastructures, which are known to be difficult to manage, especially at scale. Although there are previous works focusing on the problem of quality of service (QoS) routing in SDN networks, only few solutions have taken into consideration the network consistency, which reflects the adequacy between the decisions made and the decisions that should be taken. Therefore, we propose a network architecture that guarantees the consistency of the decisions to be taken in an SDN network. A consistent QoS routing strategy is then introduced in a way that avoids any quality degradation of prioritized traffic while optimizing resources usage. Thus, we proposed a traffic dispersion heuristic in order to achieve this goal. We compared our approach with several existing framework in terms of best‐effort flows average throughput, average video bitrate, and video quality of experience (QoE). The emulation results, which are performed using the Mininet environment, clearly demonstrate the effectiveness of the proposed approach that outperforms existing frameworks.     

Analytical solution of the linear fractional system of commensurate order

A useful representation of fractional order systems is the state space representation. For the linear fractional systems of commensurate order, the state space representation is defined as for regular integer state space representation with the state vector differentiated to a real order. This paper presents a solution of the linear fractional order systems of commensurate order in the state space. The solution is obtained using a technique based on functions of square matrices and the Cayley-Hamilton theorem. The technique developed for linear systems of integer order is extended to derive analytical solutions of linear fractional systems of commensurate order. The basic ideas and the derived formulations of the technique are presented. Both, homogeneous and inhomogeneous cases with usual input functions are solved. The solution is calculated in the form of a linear combination of suitable fundamental functions. The presented results are illustrated by analyzing some examples to demonstrate the effectiveness of the presented analytical approach.     

Improvement of postal mail sorting system

An efficient mail sorting system is mainly based on an accurate optical recognition of the addresses on the envelopes. However, the localizing of the address block (ABL) should be done before the OCR recognition process. The location step is very crucial as it has a great impact on the global performance of the system. Consequently a good localizing step leads to a better recognition rate. The limits of current methods are mainly caused by modular linear architectures used for ABL and the lack of cooperation between modules: their performances greatly depend on each independent module performance. We are presenting in this paper a new approach for ABL based on a pyramidal data organization and on a hierarchical graph coloring for classification process. This new approach presents the advantage to guarantee a good coherence between different modules and it also reduces both the computation time and the rejection rate. The proposed method gives a very satisfying rate of 98% of good locations on a set of 750 envelope images.     

Milling effect on the photo-activated properties of $$\hbox {TiO}_{2}$$ nanoparticles: electronic and structural investigations

Commercial PC105 titanium dioxide nanoparticles were studied under mechanical milling process. The effect of milling time and speed on the structural and electronic properties of \(\hbox {TiO}_{2}\) powder was then investigated using X-ray powder diffraction (XRD), dynamic light scattering (DLS), transmission electronic microscopy (TEM), electron paramagnetic resonance (EPR) and UV–visible spectroscopy. The related photo-catalytic properties of the milled nanoparticles were probed following the degradation rate of methylene orange (MO) under UV-light irradiation and through EPR spin-scavenging approach. Comparison with pristine powder shows that milled nanoparticles are significantly less reactive upon illumination, despite decreased radius and hence, higher specific area. Such low yield of reactive species is attributed to the apparition of the amorphous \(\hbox {TiO}_{2}\) and brookite phase upon milling, as well as increased charge carrier recombination as pointed out by the presence of sacrificial electron donor.