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We are given a graph G = (V ∪ T , E) , with V ∪ T the set of vertices where T is a set of terminals and E the set of edges. The multi-terminal vertex separator problem consists in finding a subset of vertices S ⊆ V of minimum size intersecting all paths between every pair of terminals. In this paper we present three extended linear integer programming formulations for the multi-terminal vertex separator problem and we develop Branch-and-Price and Branch-and-Cut-and-Price algorithms. For each formulation we present the pricing problem, the branching scheme and the computation of the dual bound used during the column generation phase. Computational results are reported comparing the performance of the formulations on a set of instances. [ABSTRACT FROM AUTHOR]

The fabrication of high performance, solution-processed CIGS family solar cells is based on high-temperature crystallization processes in chalcogen-containing atmosphere and/or using dangerous solvents like hydrazine. The non-hydrazine sulfurization- and selenization-free reports typically suffer from poor grain structures. We report a facile strategy to overcome grain growth limitations at very low temperature processing (250 °C). Selenium free Superstrate configuration CuInS 2 (CIS) solar cells are fabricated using a nanocrystals ink which avoiding from high temperature selenization or/and sulfurization is targeted. We investigated the effect of intentional M doping (M = Sb, Zn, Cd and Sn) on structural, morphological and photovoltaic response of the fabricated CIS films. It is found that inserting of Sb and Zn leads to improve the CIS crystal growth and surface morphology. Compared with the performance of the non-doped CIS cell, the Sb-doped and Zn-doped CIS solar cell displayed a remarkable efficiency enhancement of 15% and 38%, respectively. The champion device showed promising PCE of 7.24% without any anti-reflection coating. To the best of our knowledge, the obtained eeficiency is the highest efficiency for any non-vacuum deposited CuIn(S,Se) 2 superstrate solar cell to date. [ABSTRACT FROM AUTHOR]

In this study, graphene oxide/CuInS 2 /ZnO as a new photocatalyst with light absorption properties in the visible region were successfully synthesized via hydrothermal route. The UV–vis absorption spectra of the catalyst suggested that the graphene oxide/CuInS 2 /ZnO is active under visible light. It was evaluated the photocatalytic activities of graphene oxide/CuInS 2 /ZnO on the degradation of Rhodamine B under visible light irradiation and was found that the graphene oxide/CuInS 2 /ZnO obtained exhibit photocatalytic activity higher than single ZnO and CuInS 2 /ZnO. Presence of graphene oxide with high specific surface area and great conductivity make it as a good support for CuInS 2 /ZnO and improves removal efficiency for degradation of Rhodamine B. [ABSTRACT FROM AUTHOR]

A new photocatalyst, dichloro (1,10-phenanthroline-5,6-dione) palladium (II) complex supported on SBA-15 silica was synthesized by ship-in-a-bottle method. The products obtained were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Ultraviolet–Visible spectroscopy (UV–Vis), 1 H NMR spectroscopy, N 2 adsorption–desorption and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The band gap energy of the complex was determined by the diffuse reflectance spectroscopy (DRS) and density functional theory (DFT) calculation, indicating that it can be considered appropriate candidate for photocatalytic activity in the region of solar spectrum. The results indicated improved photocatalytic efficiency for the complex supported on SBA-15 silica compared to the pure complex. To improve photocatalytic activity, the effect of complex loading and optimal synthesis conditions were investigated. [ABSTRACT FROM AUTHOR]

In this work, CuInS 2 (CIS) nanoparticles were synthesized via a simple and efficient reflux route and were composite with different nanostructures of ZnO by a thermal treatment process. The particle size of 56 nm was obtained using cupper acetylacetonate (Cu(acac) 2 ), thioacetamide (C 2 H 5 NS), indium(III) chloride tetrahydrate (InCl 3 ·4H 2 O) and ethylene glycol as a solvent at the reaction time of 90 min. The product was characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and ultraviolet–visible spectroscopy (UV–vis). SEM images presented the particle morphology of the CIS sample and flower-like, narcis and particle morphologies for the ZnO samples in the arranged reaction conditions. The band gap energy of 1.55 eV estimated by the diffuse reflectance spectroscopy (DRS) for CIS nanoparticles, exhibited that this product can be appropriate for photocatalytic activity in the visible region of solar spectrum. Photocatalytic activity of ZnO/CIS nanocomposite was determined by photodegradation of crystal violet under visible light irradiation. Results showed that the presence of the CIS nanoparticles improves the efficiency of the photocatalytic activity of ZnO and the removal efficiency up to 100%, which prove capability of CIS nanoparticles to depredate crystal violet from aqueous solution. In this paper, the effects of morphology of ZnO nanostructures and initial pH of solution on the photocatalytic activity are investigated. [ABSTRACT FROM AUTHOR]

Highlights: [•] Incorporation of H4[PMo11VO40] onto Zr modified mesoporous silica was performed. [•] Adsorption behavior of sample for samarium and dysprosium removal was investigated. [•] Adsorption capacity of mesoporous silica by supporting of HMVP increased. [Copyright &y& Elsevier]

Abstract: Ordered mesoporous silica materials are one of the most extensively used adsorbents for trapping pollutants. They have many advantages such as good accessibility to active sites, rapid mass transport inside the nanostructures, and good hydrothermal stability, but most mesoporous materials do not themselves have the appropriate surface properties. To address this issue, we reported a simple method for immobilization of heteropolymetalate onto mesoporous, because they have potential sorption and ion exchange properties. Here we attempted to immobilized Tin (IV) molybdophosphate onto mesoporous silica SBA-15 and used for strontium removal from aqueous solution. The obtained products were characterized by inductively coupled plasma (ICP), XRD, N2 adsorption–desorption isotherms, scanning electron microscopy (SEM) and FT-IR. This work provides new methodology for the general synthesis of supported heteropolymetalate with large surface areas, and ordered nano porous structures. [Copyright &y& Elsevier]

Abstract: Novel hybrid polyoxometalates (POM) of α-H3PW12O40·nHMPA and α-H3PMo12O40·nHMPA composed of α-H3PW12O40 and H3PMo12O40 heteropoly acides (HPAs) and hexamethylphosphoramide (HMPA) organic substrate has been synthesized and purified. SBA-15 mesoporous silica is synthesized, using P123 surfactant via hydrothermal method, and functionalized with aminopropyl functional groups via grafting method. The synthesized mesostructured supports are used for intercalation of the hybrid POMs. The parent Keggin HPAs are also immobilized within the supports to perform closer and more efficient investigation. After characterization, effect of functional groups on immobilization pattern and quality is taken into consideration. The mesostructured organic–inorganic hybrid materials are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic absorption, and FT-IR analysis. The newly designed hybrid catalysts are investigated for heterogeneous epoxidation of olefins. Effects of temperature, oxidant, and catalyst amount are studied and the reaction conditions are optimized. An interpretation of the differences in the catalytic activity of the precursors is put forward and their catalytic activity is compared with their HPA counterparts. Furthermore, effects of functionalization on catalyst activity, stability, and reusability are taken into consideration. Results reveal that the designed mesostructured POM based hybrid catalysts can selectively and efficiently epoxidize olefins in presence of hydrogen peroxide as oxidant. The catalysts are shown to be heterogeneous and reusable without significant loss of activity in the proceeding rounds. [Copyright &y& Elsevier]

Abstract: K6P2W18O62 and K14[NaP5W30O110] polyoxometalate salts are synthesized and immobilized within MCM-48, SBA-3, SBA-15 and NH3 + functionalized mesoporous silicas. The newly designed hybrid materials are studied as catalysts for oxidation of thioethers. Preyssler complex is found to be a more active catalyst compared to its Dawson analog. Texture and chemical composition of the silica framework is shown to have indispensable effect on oxidation efficiency, stability, and reusability of catalysts. Catalysts with larger pores are proved to be more proper for the oxidation of relatively large thioethers and functionalization improves catalyst''s properties. [Copyright &y& Elsevier]

Abstract: SBA-15 mesoporous silica is synthesized using triblock copolymer P123 surfactant and chemically modified by aminopropyl, thiol, ammonium and sulfonic acid functional groups. Functionalization is performed via post synthesize method using 3-aminopropyltriethoxysilane (APTES) or 3-mercatopropyl trimethoxysilane (MPTMS) precursor. The as synthesized mesoporous systems are applied for immobilization of cyanocobalamine. Functionalization effectively improves sorption properties of the supports, while different functional groups exert different effects. The organic–inorganic mesoporous materials are characterized via X-ray diffraction (XRD), nitrogen adsorption and desorption, transmission electron microscopy (TEM), FT-IR and inductively coupled plasma-optical emission (ICP). The newly synthesized systems exhibit high catalytic activity for heterogeneous epoxidation of cyclooctene in presence of hydrogen peroxide. Reaction conditions are optimized, effect of functional groups on performance of the catalysts is taken into consideration and reusability of the designed heterogeneous systems is studied. Systems with chemically modified supports are shown to be more efficient and stable catalysts however; chemical nature of functional groups plays a crucial role. [Copyright &y& Elsevier]

Abstract: TiO2 surfactant-templated nanostructured thin film was fabricated by supramolecular templating technique using TiCl4 and P-123 as raw material and surfactant, respectively. The film was produced by Sol–gel dip coating procedure due to its simple technique as well as relatively low cost. Characterization of the product was carried out by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) specific surface areas, thermogravimetry–differential scanning calorimetry (TG–DSC) and UV–vis absorption spectroscopy. The as-prepared TiO2 film showed a quasi hexagonal mesostructure, and a further increase in the meso-scale order was observed after calcination. The prepared TiO2 film had a high surface area of 124m2 g−1. The film was 2-μm thick and had a closely packed of anatase particles. The direct and indirect band gap of the film was estimated from UV–vis spectroscopy data to be 4.16 and 3.69ev, respectively. The photocatalytic activity of the prepared TiO2 film was evaluated by Congo Red degradation. The film had excellent photocatalytic efficiencies and more than 80% Congo Red was decolorized in 60min. [Copyright &y& Elsevier]

Abstract: SBA-15 and SBA-3 mesoporous silicas are synthesised by P123 and CTAB surfactants via hydrothermal and liquid phase deposition procedures, respectively. An inorganic–organic hybrid mesoporous material is then synthesised by functionalization of SBA-15 with aminopropyl functional groups via grafting method. After characterization, effect of immobilizing support and functional groups on intercalation of phosphomolybdic acid (H3PMo12O40) is taken into consideration. The immobilization pattern is discussed and supported H3PMo12O40 catalysts are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), EDX, inductively coupled plasma (ICP), FT-IR, and UV–vis analysis. The newly synthesised hybrid catalysts are investigated for epoxidation of cyclooctene in presence of hydrogen peroxide as oxidant. The reaction mechanism is discussed. Furthermore, effects of different immobilizing supports and functionalization on catalyst activity, stability, and reusability are taken into consideration. Similar catalytic reactions are carried out with pristine supports and neat H3PMo12O40 (homogeneous). Results reveal that the mesostructured phosphomolybdic acid based catalysts are shown to be efficient and selective heterogeneous catalysts for oxidation of alkenes. [Copyright &y& Elsevier]

Abstract: A new form of polymeric compound of molybdenum, [MoO(O2)2.4,4′-bipy] n , was synthesized by a simple and inexpensive route and characterized by infrared, ultraviolet, nuclear magnetic resonance spectroscopes and thermal analysis. The prepared catalyst was used for the epoxidation of cyclohexene and cyclooctene in a heterogeneous system at room temperature. Results showed that the new form of MoO5 complex has significant potential as an oxidant in oxygen atom transfer reactions. This reagent oxidized olefins to epoxides in the presence of hydrogen peroxide with high conversions and selectivity. Effects of temperature, amount of catalyst, hydrogen peroxide and solvent in the epoxidation of substrate have been investigated. The stability of catalyst in epoxidation reactions has been investigated in homogenous system by recovering catalyst and recycling. Results showed that catalyst can be used at least for five consecutive cycles without a significant drop in yield. [Copyright &y& Elsevier]

Abstract: In this paper, we consider the independent dominating set polytope. We give a complete linear description of that polytope when the graph is reduced to a cycle. This description uses a general class of valid inequalities introduced in [T.M. Contenza, Some results on the dominating set polytope, Ph.D. Dissertation, University of Kentucky, 2000]. We devise a polynomial time separation algorithm for these inequalities. As a consequence, we obtain a polynomial time cutting plane algorithm for the minimum (maximum) independent dominating set problem on a cycle. We also introduce a lifting operation called twin operation, and discuss some polyhedral consequences. In particular, we show that the above results can be extended to a more general class of graphs. [Copyright &y& Elsevier]

In this paper we consider the linear relaxation of the k-edge connected subgraph polytope, P(G,k), given by the trivial and the so-called cut inequalities. We introduce an ordering on the fractional extreme points of P(G,k) and describe some structural properties of the minimal extreme points with respect to that ordering. Using this we give sufficient conditions for P(G,k) to be integral. [Copyright &y& Elsevier]

Abstract In this paper we consider a variant of the k -separator problem. Given a graph G = (V ∪ T , E) with V ∪ T the set of vertices, where T is a set of k terminals, the multi-terminal vertex separator problem consists in partitioning V ∪ T into k + 1 subsets { S , V 1 , ... , V k } such that there is no edge between two different subsets V i and V j , each V i contains exactly one terminal and the size of S is minimum. In this paper, we first show that the problem is NP-hard. Then we give two integer programming formulations for the problem. For one of these formulations, we investigate the related polyhedron and discuss its polyhedral structure. We describe some valid inequalities and characterize when these inequalities define facets. We also derive separation algorithms for these inequalities. Using these results, we develop a Branch-and-Cut algorithm for the problem, along with an extensive computational study. [ABSTRACT FROM AUTHOR]

Abstract: A series of cesium molybdo vanado phosphate (CsMVP) supported on platelet SBA-15 (SBA-15–%xCsMVP, x =20, 30, 40 and 50wt.%) was synthesized to develop an efficient inorganic composite ion-exchanger for gadolinium ion removal from aqueous solution. The preparation has been carried out using two-step aqueous impregnation methods. The obtained products were characterized by inductively coupled plasma (ICP), XRD, N2 adsorption–desorption isotherms, scanning electron microscopy (SEM) and FT-IR. In order to examine adsorption behavior of this compound on gadolinium removal, the effect of heteropoly metalate loading, pH, contact time, concentration of metal ion and temperature were investigated under batch system conditions. The SBA-15–30%CsMVP showed maximum adsorption capacity toward gadolinium removal. The results suggested that this methodology provides the general synthesis of supported heteropolymetalate with large surface areas, and ordered nano porous structures that can be used as inorganic composite ion-exchanger for efficient removal of gadolinium ions from aqueous solution. [Copyright &y& Elsevier]

Abstract: The Eulerian closed walk problem in a digraph is a well-known polynomial-time solvable problem. In this paper, we show that if we impose the feasible solutions to fulfill some precedence constraints specified by paths of the digraph, then the problem becomes NP-complete. We also present a polynomial-time algorithm to solve this variant of the Eulerian closed walk problem when the set of paths does not contain some forbidden structure. This allows us to give necessary and sufficient conditions for the existence of feasible solutions in this polynomial-time solvable case. [Copyright &y& Elsevier]

Abstract: A series of TiO2/SiO2 nanocomposites were synthesized via a novel sol–gel method. A phase transformation study of as-synthesized nanocomposite due to thermal treatment up to 1100°C has showed the existence of anatase phase in all the tested temperatures. At thermal treatment, when the temperature exceeded 400°C, brookite phase was formed beside anatase phase. At 950°C, the amorphous silica matrix was transformed to crystobalite and the brookite phase disappeared. Finally, the small peaks of rutile phase were detectable at 1100°C. The presence of tetrahedral coordination of TiO2 in SiO2 matrix was confirmed by UV–vis study. The produced nanocomposites have good photocatalytic properties due to its anatase phase, tetrahedral coordination of TiO2 in SiO2 matrix and very large surface area. The photocatalytic properties of the composites were compared for the degradation of Congo Red (CR) azo dye. Further studies were also devised to compare the catalytic efficiency of the composite with the synthesized pure TiO2. The results revealed that the as-prepared composite is the most effective. [Copyright &y& Elsevier]

Abstract: In this paper, we study the dominating set polytope in the class of graphs that decompose by one-node cutsets where the pieces are cycles. We describe some classes of facets and procedures to construct facets of the polytope in that class of graphs, and establish some structural properties. As a consequence we obtain a complete description of the polytope by a system of inequalities when the graph is a cycle. We also show that the separation problem related to that system can be solved in polynomial time. This yields a polynomial time cutting plane algorithm for the minimum weight dominating set problem in that case. We further discuss the applications for the class of cactus graphs. [Copyright &y& Elsevier]