High photocatalytic capacity of porous ceramic-based powder doped with MgO

Bouras Dikra,Fellah Mamoun,Mecif Abla,Barillé Régis,Obrosov Aleksei,Rasheed Mohammed 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.1

To purify water at low cost for our daily life, the effect of ceramic-based (mullite–cristobalite) and (mullite–zircon) powders doped with different amounts of magnesium oxide (MgO) (10 and 20 wt%) was studied. These compounds are made of a local raw material DD3 with addition of zirconia (ZrO2) to create an open porosity. The powders were prepared by the traditional mixing method with the help of an automated crushing. The effect of MgO doping on structural, morphological and photocatalytic properties of the material was studied by various analytical techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, infrared, and UV–visible spectrometry. The results of XRD proved that there was a deformation in the crystal structure of the two types of ceramics after addition, which resulted in a shift of the spectra to the right, while SEM proved the presence of pores with a larger size as the proportion of MgO increases. The chemical composition of the basic components of the ceramic compounds as well as the additive was confirmed with EDS and IR spectra. The final results show that ceramics with added zirconia (DD3Z) and doped with 10% of MgO have a better photocatalytic efficiency than ceramics without zirconia. This important effect could be related to the higher rate of porosity, which provides a more active surface. The 10% MgO content showed a high photoactivity of 77.33% in only 15 min. The maximum hydrolysis rate obtained with Orange II was 92.95% after a period of 45 min with DD3Z/MgO powders.

Influence of viscosity modifying admixtures on the rheological behavior of cement and mortar pastes

Bouras, R.,Kaci, A.,Chaouche, M. 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.1

The influence of Viscosity-modifying admixtures (VMA) dosage rate on the steady state rheological properties, including the yield stress, fluid consistency index and flow behaviour index, of cementitious materials is considered experimentally. The investigation is undertaken both at cement paste and mortar scales. It is found that the rheological behaviour of the material is in general dependent upon shear-rate interval considered. At sufficiently low shear-rates the materials exhibit shear-thinning. This behaviour is attributed to flow-induced defloculation of the solid particles and VMA polymer disentanglement and alignment. At relatively high shear-rates the pastes becomes shear-thickening, due to repulsive interactions among the solid particles. There is a qualitative difference between the influence of VMA dosage at cement and mortar scales: at cement scale we obtain a monotonic increase of the yield stress, while at mortar scale there exists an optimum VMA dosage for which the yield stress is a minimum. The flow behaviour index exhibit a maximum in the case of cement pastes and monotonically decreases in the case of mortars. On the other hand, the fluid consistency index presents a minimum for both cement pastes and mortars.

Influence of viscosity modifying admixtures on the rheologicalbehavior of cement and mortar pastes

R. Bouras,A. Kaci,M. Chaouche 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.1

The influence of Viscosity-modifying admixtures (VMA) dosage rate on the steady state rheological properties, including the yield stress, fluid consistency index and flow behaviour index, of cementitious materials is considered experimentally. The investigation is undertaken both at cement paste and mortar scales. It is found that the rheological behaviour of the material is in general dependent upon shear-rate interval considered. At sufficiently low shear-rates the materials exhibit shear-thinning. This behaviour is attributed to flow-induced defloculation of the solid particles and VMA polymer disentanglement and alignment. At relatively high shear-rates the pastes becomes shear-thickening, due to repulsive interactions among the solid particles. There is a qualitative difference between the influence of VMA dosage at cement and mortar scales: at cement scale we obtain a monotonic increase of the yield stress, while at mortar scale there exists an optimum VMA dosage for which the yield stress is a minimum. The flow behaviour index exhibit a maximum in the case of cement pastes and monotonically decreases in the case of mortars. On the other hand, the fluid consistency index presents a minimum for both cement pastes and mortars.

Study on dynamic adsorption and chemical regeneration of Cd(II) from textile effluents by new granular composite based on gluten

Louadj, Amel,Bouras, Omar,Rebahie, Ihssene,Cheknane, Omar,Zermane, Faiza Techno-Press 2021 Advances in environmental research Vol.10 No.2

Composite granules (named Fe-PILMG) based on both an Algerian montmorillonite with iron and gluten as an inert binder are prepared and used in the elimination of cadmium by dynamic adsorption in fixed bed columns. This study is essentially focused on the adsorption of Cd (II) in dynamic mode on a fixed bed based on Fe-PILMG sorbent granules followed by a study on the chemical regeneration of these new saturated adsorbents. The various regeneration tests are carried out with NaOH solution. The experimental data on the elimination of Cd (II) (pH = 7, T = 20 ± 2℃) in dynamic mode reveal that this adsorption is considerably influenced by the flow rate (2 to 5 mL min-1), Cd (II) initial concentration (20 to 50 mg L-1), and bed height (5 and 15 cm) and that a modification of each of these parameters can strongly influence the efficiency of this process. The assessment of the experimental data is carried out using the Thomas, Yoon & Nelson and Bohart-Adams models. The fit of the experimental and modeled breakthrough curves indicates excellent applicability of the mathematical models studied which is confirmed by high values of the correlation coefficient for the Bohart-Adams model (R² = 0.99, model constants N0 = 634.87 mg L-1, kBA = 0.079 (L (mg min)-1), from Yoon and Nelson model (R² = 0.97, ζ = 413.03 min, KYN = 0.0049 min-1), Thomas (R² = 0.98, q0 = 49.03 mg g-1, KTH = 5.21 mL (mg. min)-1).

Nd-Doped SnO₂ and ZnO for Application in Cu(InGa)Se₂ Solar Cells

Park, Hyeonwook,Alhammadi, Salh,Bouras, Karima,Schmerber, Guy,Ferblantier, Gé,rald,Dinia, Aziz,Slaoui, Abdelilah,Jeon, Chan-Wook,Park, Chinho,Kim, Woo Kyoung American Scientific Publishers 2017 Science Of Advanced Materials Vol.9 No.12

Trade Policy and African Participation in Global Value Chains: Does Trade Facilitation Matter?

Moukaila Mouzamilou Takpara(Moukaila Mouzamilou Takpara ),Constant Fouopi Djiogap(Constant Fouopi Djiogap ),Bouraïma Sawadogo(Bouraïma Sawadogo ) 세종대학교 경제통합연구소 2023 Journal of Economic Integration Vol.38 No.1

This study offers an empirical appraisal of the contribution of trade facilitation for Sub-Saharan Africa (SSA) countries participation in global value chains. We used new value-added data on a panel of 25 countries over the period 2004-2017. The results using pooled ordinary least squares (OLS) regression and instrumental variable-two-stage least squares (IV-2SLS) estimators reveal that trade facilitation indicators such as physical infrastructure, information and communication technology, and border and transport efficiency support SSA countries' participation in global value chains. More interestingly, these results are robust at the sectoral level, particularly in agriculture, manufacturing, and textiles & clothing sectors for physical infrastructure and ICT, while the business environment is conducive to upstream integration of GVCs in the agriculture and textiles & clothing sectors. These results underscore the increased importance of trade facilitation in the era of global value chains and call for well-targeted sectoral policies to reap the benefits of GVCs.

A new type of homoxylous Mesozoic wood from Asia, with palaeogeographical and palaeoecological implications

Changwhan Oh,Anais Boura,Marc Philippe,Denise Pons 대한지질학회 2013 대한지질학회 학술대회 Vol.2013 No.10

Ablation of very long acyl chain sphingolipids causes hepatic insulin resistance in mice due to altered detergent‐resistant membranes

Park, Joo‐,Won,Park, Woo‐,Jae,Kuperman, Yael,Boura‐,Halfon, Sigalit,Pewzner‐,Jung, Yael,Futerman, Anthony H. Wiley Subscription Services, Inc., A Wiley Company 2013 Hepatology Vol.57 No.2

<P><B>Abstract</B></P><P>Sphingolipids are important structural components of cell membranes and act as critical regulators of cell function by modulating intracellular signaling pathways. Specific sphingolipids, such as ceramide, glucosylceramide, and ganglioside GM3, have been implicated in various aspects of insulin resistance, because they have been shown to modify several steps in the insulin signaling pathway, such as phosphorylation of either protein kinase B (Akt) or of the insulin receptor. We now explore the role of the ceramide acyl chain length in insulin signaling by using a ceramide synthase 2 (CerS2) null mouse, which is unable to synthesize very long acyl chain (C22‐C24) ceramides. CerS2 null mice exhibited glucose intolerance despite normal insulin secretion from the pancreas. Both insulin receptor and Akt phosphorylation were abrogated in liver, but not in adipose tissue or in skeletal muscle. The lack of insulin receptor phosphorylation in liver correlated with its inability to translocate into detergent‐resistant membranes (DRMs). Moreover, DRMs in CerS2 null mice displayed properties significantly different from those in wild‐type mice, suggesting that the altered sphingolipid acyl chain length directly affects insulin receptor translocation and subsequent signaling. <I>Conclusion:</I> We conclude that the sphingolipid acyl chain composition of liver regulates insulin signaling by modifying insulin receptor translocation into membrane microdomains. (H<SMALL>EPATOLOGY</SMALL> 2013)</P>