Optimization of synthesis procedures for structured PSA adsorbents

Structured adsorbents in the form of supported thin zeolite films may represent a competitive alternative to traditional zeolite adsorbents in form of beads or pellets used in PSA processes, due to the reduction of mass- and heat-transfer limitations typical of packed beds. Thin NaX films were grown by hydrothermal treatment using a clear solution on cordierite monoliths. Films grown by a multiple synthesis procedure were dense and uniform with a very small amount of sediments adjacent to the film, which may be an advantage in PSA applications. The CO₂ adsorption capacity and the pressure drop for the supported films were compared to those of a packed NaX bed. Although the adsorption capacity of the column filled with the structured adsorbents was 67 times lower than when the column was filled with zeolite beads, the pressure drop was 100 times lower for the structured adsorbent. The adsorption capacity can be increased by increasing the film thickness or the cell density of the monoliths without increasing the pressure drop significantly, indicating the potential advantage of structured adsorbents in PSA processes. Further investigations are needed in order to prove this hypothesis.     

Simultaneous analysis of polychlorinated biphenyls and organochlorine pesticides in water by headspace solid-phase microextraction with gas chromatography-tandem mass spectrometry

Headspace solid-phase microextraction combined with gas chromatography-ion trap tandem mass spectrometry (HS-SPME-GC-ITMS-MS) method has been developed and studied for the simultaneous determination of 15 organochlorine pesticides (OCPs) and 20 polychlorinated biphenyls (PCBs) in aqueous samples. To perform the HS-SPME polydimethylsiloxane (PDMS) (7, 30 and 100 microm film thickness) and polydimethylsiloxane-divinylbenzene (PDMS-DVB) fibers were initially compared on the basis of their absorption capacities for the selected compounds, and PDMS 100 microm film thickness was selected to accomplish the rests of essays. The influence of various parameters on OCPs and PCBs extraction efficiency by HS-SPME was thoroughly studied using GC-electron capture detector (ECD). Parameters such as collision induced dissociation (CID) resonant excitation amplitude and RF storage level were optimized to increase specificity and sensibility for ITMS-MS analysis. The performance of proposed HS-SPME-GC-ITMS-MS methodology with respect to linearity, reproducibility and limit of detection (LOD) was evaluated by water spiked with target compounds. The linear range of most compounds was found to be between 0.01 and 1 ng mL(-1) and the limits of detection were between 0.4 and 26 pg mL(-1). The reproducibility of the method (n = 6), expressed as relative standard deviation (RSD), was between 5 and 21%. Finally, developed procedure was applied to determine selected OCPs and PCBs in river water samples in concentration below 0.1 ng mL(-1) can be easily carried out with ultra-selectivity and precision.     

Highly Selective and Sensitive Aggregation-Induced Emission of Fluorescein-Coated Metal Oxide Nanoparticles

We report the synthesis, characterization, and photophysical properties of novel metal oxide nanoparticles (NPs) coated with specially designed fluorescein substituents which are capped with electron-withdrawing groups. The fluorescein-coated nanoparticles were synthesized in excellent yields, and their structures were confirmed using various advanced spectroscopic, instrumental, and surface analysis techniques, revealing the formation of the target functionalized nanoparticles (FNPs) which show superior chemical and thermal stabilities. In addition, the photophysical properties of the FNPs were examined using UV-visible absorption and fluorescence spectroscopy. These latter techniques disclosed aggregation-induced emission (AIE) properties for most of the target FNPs, namely those which are soluble in common organic solvents at selective concentration ranges of water fractions in the solvent mixture.     

Hom-Lie quadratic and Pinczon Algebras

Presenting the structure equation of a hom-Lie algebra 𝔤, as the vanishing of the self commutator of a coderivation of some associative comultiplication, we define up to homotopy hom-Lie algebras, which yields the general hom-Lie algebra cohomology with value in a module. If the hom-Lie algebra is quadratic, using the Pinczon bracket on skew symmetric multilinear forms on 𝔤, we express this theory in the space of forms. If the hom-Lie algebra is symmetric, it is possible to associate to each module a quadratic hom-Lie algebra and describe the cohomology with value in the module.     

Algèbre Pré-Gerstenhaber à homotopie près

This paper is concerned by the concept of algebra up to homotopy for a structure defined by two operations . and $[,]$. An important example of such a structure is the Gerstenhaber algebra (i.e. commutatitve structure with degree 0 and Lie structure with degree ?1). The notion of Gerstenhaber algebra up to homotopy ($G_{\infty }$ algebra) is known: it is a codifferential bicogebra.Here, we give a definition of pre-Gerstenhaber algebra (pre-commutative and pre-Lie) allowing a similar construction for a $\text{pre}{G}_{\infty }$ algebra.Given a structure of pre-commutative (Zinbiel) and pre-Lie algebra and working over the corresponding Koszul dual operads, we will give an explicit construction of the associated pre-Gerstenhaber algebra up to homotopy: it is a bicogebra (Leibniz and permutative) equipped with a codifferential which is a coderivation for the two coproducts.     

One-pot green synthesis,study of fluorescence properties,and biological activity of pyrano[3,2-c]chromenes derivatives via mesoporous materials MgO/SBA-15

This current work describes the preparation of MgO-SBA-15 catalysts by ultrasonic method, and it is characterized by the different analysis techniques of XRD, BET, SEM, and IRTF. In order to find out an application for this mesoporous material, MgO/SBA-15 was used as a heterogeneous catalyst in the one-pot synthesis of pyrano[3,2-c]chromenes derivatives isolated at room temperature reaction according to green chemistry criteria. To enhance these derivatives, a spectroscopic study of molecular fluorescence properties was carried out as well as an identification analysis by nuclear magnetic resonance and FTIR was used. Furthermore, biological activity experiment is also carried out, from where the obtained test results were satisfactory for AC09 , AC05 , and AC10 compounds and they are checked after computation by molecular modeling.     

Solubility study of sodium, potassium and calcium sulfates and chlorides, in ammonia

Solubility of sodium, potassium and calcium sulfates and chlorides in 28% ammonia solution was determined through monitoring conductivity measurements and kinetics of solids dissolution as a function of temperature and stirring time. The major findings of the present study show that Na₂SO₄ and K₂SO₄ solutions conductivity follow straight linear segments with different slopes. However, in case of NaCl, KC1, CaCl₂ and CaSO₄ · 2H₂O, conductivity curves were continuous, monotonous and reach constants maximum values. The hypothesis of complex formation or dissolution via intermediaries such as NaNH₄SO₄ and KNH₄SO₄ salts seams to be true, through X-ray diffraction study of resulting deposits. Furthermore, the dissolution rates at 25°C of potassium and calcium chlorides in ammonia solution are higher than that reported in the literature for water. In fact, ammonia significantly reduces the solubility of K₂SO₄; conversely, a slight increase in this parameter was observed for CaSO₄.     

Synthesis and characterization of new thiazolidinones containing coumarin moieties and their antibacterial and antioxidant activities

New coumarin derivatives, namely (2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-phenylthiazolidin-3-yl)acetamide, N-(2-(3-methoxyphenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide, 2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-(2,3,4trimethoxyphenyl)thiazolidin-3-yl)acetamide and N-(2-(4-bromophenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide) were synthesized starting from 4-methyl-7-hydroxycoumarin. The structures of the obtained compounds were confirmed by analytical IR and NMR spectra to elucidate the different positions of protons and carbons and as well as theoretical studies (DFT/B3LYP). The new compounds were screened for antibacterial activity. Most of them are more active against E. coli S. aureus and B. subtilis than standard references.     

Numerical computation of natural convection in an isosceles triangular cavity with a partially active base and filled with a Cu–water nanofluid

This paper discusses the results of a study related to natural convection cooling of a heat source located on the bottom wall of an inclined isosceles triangular enclosure filled with a Cu water-nanofluid. The right and left walls of the enclosure are both maintained cold at constant equal temperatures, while the remaining parts of the bottom wall are insulated. The study has been carried out for a Rayleigh number in the range 10⁴ ≤ Ra ≤ 10⁶, for a heat source length in the range 0.2 ≤ ε ≤0.8, for a solid volume fraction in the range 0 ≤ ?≤0.06 and for an inclination angle in the range 0° ≤ δ≤45°. Results are presented in the form of streamline contours, isotherms, maximum temperature at the heat source surface and average Nusselt number. It is noticed that the addition of Cu nanoparticles enhances the heat transfer rate and therefore cooling effectiveness for all values of Rayleigh number, especially at low values of Ra. The effect of the inclination angle becomes more noticeable as one increases the value of Ra. For high Rayleigh numbers, a critical value for the inclination angle of δ = 15° is found for which the heat source maximum temperature is highest.     

Structural study,intermolecular interactions in view of X-ray and Hirshfeld surface analysis,DSC characterization,and electrical properties of <Emphasis Type="Italic">bis</Emphasis>-(4-benzylpyridinium) tetrabromozincate

The synthesis and crystal structure of the bis-(4-benzylpyridinium) tetrabromozincate(II) “(4-BP)₂[ZnBr₄]” salt are reported in the present paper. After an X-ray investigation, it has been shown that the title compound belongs to the centrosymmetric monoclinic system at 296 K, in the space group P2₁/n with the following lattice parameters a = 15.0764(8) Å, b = 22.5575(12) Å, c = 16.0739(9) Å, and β = 93.887(3)°. The FT-IR and Raman spectra confirm the presence of both cationic and anionic parts. The crystal packing is governed by an extensive network: N–H…Br, (N: pyridinium), C–H…Br hydrogen bonds, π…π, and C–H…π stacking between identical 4-BP (aromatic–aromatic), in which they may be effective in the stabilization of the crystal structure. Moreover, Hirshfeld surface analysis was used for visually analyzing intermolecular interactions in crystal structures. The phase transitions at T = 323 K have been confirmed by the differential scanning calorimetry. The electrical technique was measured in the 209 Hz–5-MHz frequency range and 298–393-K temperature intervals. The evolution of the dielectric constant as a function of frequency and temperature proved the presence of a first-order phase transition at 323 K.

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