A Green Approach for the Synthesis of Silver Nanoparticles Using Root Extract of <Emphasis Type="Italic">Chelidonium majus:</Emphasis> Characterization and Antibacterial Evaluation

In this study, silver nanoparticles (Ag-NPs) have been synthesized using extract of Chelidonium majus root in aqueous solution at room temperature. The root extract was able to reduce Ag⁺ to Ag⁰ and stabilized the nanoparticles Different physico-chemical techniques including UV–Vis spectroscopy, transmission electron microscopy and powder X-ray diffraction (PXRD) were used for the characterization of the biosynthesized Ag-NPs obtained. The surface plasmon resonance band appeared at 431 nm is an evidence for formation of Ag-NPs. TEM imaging revealed that the synthesized Ag-NPs have an average diameter of around 15 nm and with spherical shape. Moreover the crystalline structure of synthesized nanoparticles was confirmed using XRD pattern. Furthermore antimicrobial activities of synthesized Ag-NPs were evaluated against Escherichia coli -ATCC 25922 and Pseudomonas aeruginosa ATCC 2785 bacteria strain.     

Facile Biosynthesis of Silver Nanoparticles Using <Emphasis Type="Italic">Descurainia sophia</Emphasis> and Evaluation of Their Antibacterial and Antifungal Properties

The objective of the present study was to evaluate efficiency of silver nanoparticles (Ag-NPs) biosynthesis using Descurainia sophia as a novel biological resource. The resulting synthesized Ag-NPs were characterized using UV visible spectroscopy, X-ray diffraction, transmission electron microscopy and dynamic light scattering (DLS). The UV–Vis spectra gave surface plasmon resonance at ~420 nm. TEM images revealed formation spherical shaped Ag-NPs with size ranged from to 1–35 nm. DLS confirmed uniformity of the synthesized Ag-NPs with an average size of ~30 nm. Following, the antibacterial and antifungal activities of the synthesized Ag-NPs were investigated. The concentration 25 µg/ml of the Ag-NPs showed maximum inhibitory effect on mycelium growth of Rhizoctonia solani (More than 86 % inhibition), followed by 15 µg/ml (55 % inhibition) and 10 µg/ml (63 % inhibition). The minimum inhibitory concentration and minimum bactericidal concentration of Ag-NPs against Agrobacterium tumefaciens (strain GV3850) and A, rhizogenes (strain 15843) were 4 and 8 µg/ml, respectively. The Ag-NPs were stable in vitro for 3 months without any precipitation or decrease of antifungal effects. Finally, it could be concluded that D. sophia can be used as an effective method for biosynthesis of nanoparticles, especially Ag-NPs.     

Syntheses and structures of four new mixed‐amide phosphoric triamides

Phosphoric triamides have extensive applications in biochemistry and are also used as O‐donor ligands. Four new mixed‐amide phosphoric triamide structures, namely rac‐N‐tert‐butyl‐N′,N′′‐dicyclohexyl‐N′′‐methylphosphoric triamide, C₁₇H₃₆N₃OP, (I), rac‐N,N′‐dicyclohexyl‐N′‐methyl‐N′′‐(p‐tolyl)phosphoric triamide, C₂₀H₃₄N₃OP, (II), N,N′,N′′‐tricyclohexyl‐N′′‐methylphosphoric triamide, C₁₉H₃₈N₃OP, (III), and 2‐[cyclohexyl(methyl)amino]‐5,5‐dimethyl‐1,3,2λ⁵‐diazaphosphinan‐2‐one, C₁₂H₂₆N₃OP, (IV), have been synthesized and studied by X‐ray diffraction and spectroscopic methods. Structures (I) and (II) are the first diffraction studies of acyclic racemic mixed‐amide phosphoric triamides. The P—N bonds resulting from the different substituent –N(CH₃)(C₆H₁₁), (C₆H₁₁)NH–, 4‐CH₃‐C₆H₄NH–, (tert‐C₄H₉)NH– and –NHCH₂C(CH₃)₂CH₂NH– groups are compared, along with the different molecular volumes and electron‐donor strengths. In all four structures, the molecules form extended chains through N—H…O hydrogen bonds.     

Grafting of temperature sensitive PNIPAAm on hydrophilised polysulfone UF membranes

Poly(N-isopropyl acrylamide) (PNIPAAm) was grafted on a polysulfone UF membrane. The changes of permeability as well as retention of PEG (35 kg/mol) and Dextran (500 kg/mol) between 23 and 60 °C were determined for both grafted and unmodified membranes. The results showed that the viscosity corrected water permeability and solute retention were almost constant for the unmodified membranes within the measured temperature range, the permeability of the grafted membranes increased and the retention of Dextran and PEG decreased with temperature. The variation of changes was most obvious in the temperature range 27–37 °C for the modified membranes due to the lower critical solution temperature (LCST) of PNIPAAm. The location and profile of PNIPAAm inside and on the surface of the membrane were analysed by SEM and FTIR. Depth profile calculation for FTIR spectra showed that PNIPAAm was mostly placed inside the membrane (at a depth of 1.06–1.10 μm from the surface) rather than on the surface. The amount of grafted PNIPAAm was low and did not significantly affect the morphology of the membrane. Therefore, a difference in SEM pictures of modified and unmodified membranes could not be seen. The modified membrane exhibited a clearly different thermal response compared to the unmodified one.     

BTX Removal from Polluted Water Through Bioleaching Processes

In this study, benzene, toluene, and xylenes (BTX) removal from contaminated water by physical, chemical, and biological processes was studied. Results showed that air sparging in polluted water can reduce monoaromatic compounds from 140,000 to about 5 microg/l in only 1 h process with a gassing rate of 0.33 VVM. This method cannot be considered as a green technology as pollutants are only transferred from the liquid phase to the gas phase The ultimate objective of this research was thus to evaluate the efficiency of a strategy involving BTX adsorption by granular-activated charcoal (GAC) and subsequent regeneration of this support by a bioleaching process. Analysis of such processes requires the building of analytical tools able to accurately determine the contents of the contaminants in samples containing biomass to make possible the calculation of reliable material balances. Current investigation showed that BTX are readily trapped by GAC particles with low further release in the liquid medium whereas they remain at least partially available for in situ biodegradation. BTX adsorption onto the GAC was shown to reach maximum solute retention close to 350, 250, and 150 (as mg/g GAC) for xylenes, toluene, and benzene, respectively. This approach, which could afford efficient biological active carbon regeneration, is very promising for the removal of BTX compounds from water without any further environment damage.     

The strong persistence property and symbolic strong persistence property

Czechoslovak Mathematical Journal - Let I be an ideal in a commutative Noetherian ring R. Then the ideal I has the strong persistence property if and only if (Ik+1: RI) = Ik for all k, and I has...     

γ‐Fe2O3@Cu3Al‐LDH‐TUD as a new Amphoteric,Highly Efficient and Recyclable Heterogeneous Catalyst for the Solvent‐free Synthesis of Dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens

Thiourea dioxide was immobilized on γ‐Fe₂O₃@Cu₃Al‐LDH magnetic nanoparticles to prepare the γ‐Fe₂O₃@Cu₃Al‐LDH‐TUD MNPs. The structure and properties of these magnetic nanoparticles were established by FT‐IR, EDX, SEM, XRD, and hystogram of particle size analytical methods. The results obtained from these analytical methods confirmed the successful immobilization of the thiourea dioxide onto the magnetic support. The synthesized magnetic nanoparticles (MNPs) exhibited high catalytic activity in one‐pot three‐component reactions under mild and solvent‐free conditions for the synthesis of diverse ranges of dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens. All the reactions proceeded smoothly to furnish the respective products in excellent yields. Simple isolation of the products, avoidance of harmful organic solvents, versatility of the catalyst and its easy magnetic separation and reusability with no significant loss of activity are the main advantages of the present method.     

Metabolites from the biodegradation of 1,6‐hexanediol dibenzoate,a potential green plasticizer,by Rhodococcus rhodochrous

Metabolites from the biodegradation of a potential plasticizer 1,6‐hexanediol dibenzoate in the presence of n‐hexadecane as a co‐substrate by the common soil organism Rhodococcus rhodochrous were identified using GC/MS and Fourier transform mass spectroscopy (FTMS) techniques. Trimethylsilylation of compounds from the biodegradation broth permitted detection of the following metabolites: 1‐hexadecyl benzoate, 6‐benzoyloxyhexanoic acid, 4‐benzoyloxybutanoic acid, 6‐benzoyloxyhexan‐1‐ol and benzoic acid. The presence of these metabolites was confirmed by repeating the biodegradation with 1,6‐hexanediol di[²H₅]benzoate, by measurement of their exact masses in FTMS and by comparison with available authentic materials. The results show that biodegradation of 1,6‐hexanediol dibenzoate by R. rhodochrous does not lead to the accumulation of persistent metabolites as has been reported for commercial dibenzoate plasticizers. Copyright © 2009 John Wiley & Sons, Ltd.     

Development and validation of SuperDEM for non-spherical particulate systems using a superquadric particle method

This article presents the development and validation of the Superquadric Discrete Element Method(SuperDEM) for non-spherical particle simulation using a superqu...     

(±)‐6‐Benzyl‐3,3‐di­methyl­morpholine‐2,5‐dione and its 5‐mono­thio and 2,5‐di­thio derivatives

The morpholine ring of the title dione, C₁₃H₁₅NO₃, shows a boat conformation that is distorted towards a twist‐boat, with the boat ends being the two Csp³ atoms of the ring. The benzyl substituent is in the favoured `exo' position. In the mono­thione derivative, (±)‐6‐benzyl‐3,3‐di­methyl‐5‐thioxo­morpholin‐2‐one, C<sub>13</sub>H<sub>15</sub>NO<sub>2</sub>S, this ring has a much flatter conformation that is midway between a boat and an envelope, with the di­methyl end being almost planar. The orientation of the benzyl group is `endo'. The di­thione derivative, (±)‐6‐benzyl‐3,3‐di­methyl­morpholine‐2,5‐di­thione, C₁₃H₁₅N­OS₂, has two symmetry‐independent mol­ecules, which show different puckering of the morpholine ring. One mol­ecule has a flattened envelope conformation distorted towards a screw‐boat, while the conformation in the other mol­ecule is similar to that in the mono­thione derivative. Intermolecular hydrogen bonds link the mol­ecules in the three compounds, respectively, into centrosymmetric dimers, infinite chains, and dimers made up of one of each of the symmetry‐independent mol­ecules.