Carbon Nanotubes Hybrid Hydrogels for Environmental Remediation: Evaluation of Adsorption Efficiency under Electric Field

The performance of Carbon Nanotubes hybrid hydrogels for environmental remediation was investigated using Methylene Blue (MB), Rhodamine B (RD), and Bengal Rose (BR) as model contaminating dyes. An acrylate hydrogel network with incorporated CNT was synthesized by photo-polymerization without any preliminary derivatization of CNT surface. Thermodynamics, isothermal and kinetic studies showed favorable sorption processes with the application of an external 12 V electric field found to be able to influence the amount of adsorbed dyes: stronger interactions with cationic MB molecules (qexp and qexp12 of 19.72 and 33.45 mg g⁻¹, respectively) and reduced affinity for anionic RD (qexp and qexp12 of 28.93 and 13.06 mg g⁻¹, respectively) and neutral BR (qexp and qexp12 of 36.75 and 15.85 mg g⁻¹, respectively) molecules were recorded. The influence of pH variation on dyes adsorption was finally highlighted by reusability studies, with the negligible variation of adsorption capacity after five repeated sorption cycles claiming for the suitability of the proposed systems as effective sorbent for wastewater treatment.     

Polymerization of 1-vinylcyclohexene in the presence of group 4 metallocenes – MAO catalysts

1-Vinylcyclohexene was polymerized in the presence of several homogeneous catalytic systems consisting of methylaluminoxane and group 4 metallocenes such as CpTiCl₃, [isopropyl(cyclopentadienyl)(1-fluorenyl)]ZrCl₂,rac-[ethylenebis(1-indenyl)] ZrCl₂, (CH₃)₂Si(Cp)₂ZrCl₂, CpZrCl₃. The structure of the polymers depends on the catalyst. In fact, with CpTiCl₃, [isopropyl(cyclopentadienyl)(1-fluorenyl)]ZrCl₂ and rac-[ethylenebis-(1-indenyl)]ZrCl₂ the polymers are chemo-, regio- and stereoregular with 1,4 cis, 1,4 trans and 1,2 isotactic structure, respectively.     

Flame Induced Flow Features in the Presence of Darrieus-Landau Instability

The onset of hydrodynamic or Darrieus-Landau (DL) instability can largely impact on premixed flame morphology, turbulent flame speed and induced flow field. In this work, we focus on the latter induced flow by means of two dimensional direct numerical simulations (DNS) of slot burner flames performed in a parametric fashion. Results from linear stability analysis are used to select the adequate parameter range to be investigated. The presence of DL instability is initially assessed using a recently proposed statistical marker related to flame morphology. The differences between stable and unstable flames are then statistically investigated, utilizing a single, laminar, DL-induced corrugation as a reference state. Such DL-induced effects are investigated at various turbulence intensities, in terms of local propagation, induced strain rate patterns and flow field as well as vorticity production and transformation. Using displacement speed as a measure of local propagation, no noticeable statistical difference is observed between stable and unstable flames while strain rate and vorticity patterns are shown to be largely influenced by the DL induced morphology. From the modeling point view, an enhancement of counter gradient type transport for turbulent scalar fluxes is observed for hydrodynamically unstable flames.     

Intercalation of tris-(2,2′-bipyridyl) ruthenium (II) in α- and γ-zirconium phosphate: synthesis, thermal behaviour and X-ray characterization

Intercalation compounds such as the ruthenium trisbipyridyl complex in inorganic layered ion-exchangers (α- and γ-zirconium phosphate) have been synthesized using the batch method. There is no loss of bipyridyl ligand from the metal ion during the exchange of the ruthenium trisbipyridyl complex in these host matrices. The materials obtained are thermally stable up to ~330 °C (γ-phase) or ~380 °C (α-phase). The complex decomposition occurs in one or more steps and at ~600 °C the complex decomposition is complete. The X-ray patterns of ruthenium materials show a new phase with an increase in the interlayer distance with respect to the initial phase. Microanalysis measurements confirm the fact that the ruthenium complex is not modified when exchanged and the complex decomposition depends on its position in the host matrices.     

Energetic of molecular interface at metal-organic heterojunction: the case of thiophenethiolate chemisorbed on Au(111)

To probe the cooperativity of charge transfer between organoimido and hexamolybdate, and enhance the second-order nonlinear optical (NLO) response of organoimido derivatives of hexamolybdates, electronic structures and second-order NLO properties of a series of charge-transfer covalently bonded organoimido derived hexamolybdate complexes with donor-(π conjugated bridge)-acceptor-(π conjugated bridge)-donor or acceptor-(π conjugated bridge)-donor-(π conjugated bridge)-acceptor structures were studied by density functional theory. Studies show that different combinations of the donor, acceptor, heterocycle, –C≡C– and –N=N– moieties, and orientation of heterocycle remarkably affect the second-order NLO responses. The complexes containing electronic acceptor matched with the direction of charge transfer possess remarkable large molecular second-order polarizabilities. Electronic transitions to crucial excited states show that x-polarized transition, contributed to the off-diagonal second-order polarizabiliy tensor (β_zxx), possesses lower excited energy compared with z-polarized transition which accounted for the diagonal second-order polarizabiliy tensor (β_zzz) and thus led to the large in-plane nonlinear anisotropy (u = β_zxx/β_zzz) value, as well as good two-dimensional (2-D) second-order NLO properties. These complexes can be used as excellent 2-D second-order NLO materials from the standpoint of both large β and u values.     

Weakly <Emphasis Type="Italic">φ</Emphasis>-pairs and common fixed points in cone metric spaces

In this paper we introduce a weak contractive condition, called weakly φ-pair, for two mappings in the framework of cone metric spaces and we prove a theorem which ensures existence and uniqueness of common fixed points for such mappings. Also we obtain a result on points of coincidence. These results extend and generalize well-known comparable results in the literature. The authors are supported by Università degli Studi di Palermo, R. S. ex 60%.     

Efficient and suitable preparation of N-sulfonyl-1,2,3,4-tetrahydroisoquinolines and ring analogues using recyclable H6P2W18O62·24H2O/SiO2 catalyst

Silica gel-supported H₆P₂W₁₈O₆₂·24H₂O is an efficient and recyclable catalyst for the synthesis of biologically important molecules. Several substituted N-sulfonyl-1,2,3,4-tetrahydroisoquinolines and ring analogues can be prepared in very good yields and purity by direct reaction of N-aralkylsulfonamides and sym-trioxane by a Pictet-Spengler reaction in the presence of a catalytic amount of silica gel-supported H₆P₂W₁₈O₆₂·24H₂O. Reactions were performed in a low volume of toluene, at 70 °C and for a short time, typically 15 to 30 min. The title heterocyclic compounds were prepared in very good yields (60%–95%) using the described procedure results in a clean and useful alternative, which has the advantages of a greener methodology with operative simplicity, use of a reusable and non-corrosive solid catalyst, soft reaction conditions, low reaction times, and good yields.     

Source apportionment of groundwater pollutants in Apulian agricultural sites using multivariate statistical analyses: case study of Foggia province

Background

Ground waters are an important resource of water supply for human health and activities. Groundwater uses and applications are often related to its composition, which is increasingly influenced by human activities.In fact the water quality of groundwater is affected by many factors including precipitation, surface runoff, groundwater flow, and the characteristics of the catchment area. During the years 2004-2007 the Agricultural and Food Authority of Apulia Region has implemented the project “Expansion of regional agro-meteorological network” in order to assess, monitor and manage of regional groundwater quality. The total wells monitored during this activity amounted to 473, and the water samples analyzed were 1021. This resulted in a huge and complex data matrix comprised of a large number of physical-chemical parameters, which are often difficult to interpret and draw meaningful conclusions. The application of different multivariate statistical techniques such as Cluster Analysis (CA), Principal Component Analysis (PCA), Absolute Principal Component Scores (APCS) for interpretation of the complex databases offers a better understanding of water quality in the study region.

Results

Form results obtained by Principal Component and Cluster Analysis applied to data set of Foggia province it’s evident that some sampling sites investigated show dissimilarities, mostly due to the location of the site, the land use and management techniques and groundwater overuse. By APCS method it’s been possible to identify three pollutant sources: Agricultural pollution 1 due to fertilizer applications, Agricultural pollution 2 due to microelements for agriculture and groundwater overuse and a third source that can be identified as soil run off and rock tracer mining.

Conclusions

Multivariate statistical methods represent a valid tool to understand complex nature of groundwater quality issues, determine priorities in the use of ground waters as irrigation water and suggest interactions between land use and irrigation water quality.

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Random benzotrithiophene-based donor-acceptor copolymers for efficient organic photovoltaic devices

A series of benzotrithiophene-containing random terpolymers for polymer solar cells is reported. Through variations of the two other components in the terpolymers, the absorption profile and the frontier energy levels are optimized and maximum power conversion efficiencies are nearly doubled (5.14%) relative to the parent alternating copolymer.