The effect of NaCl and Na2SO4 concentration in aqueous phase on the phase inversion temperature O/W nanoemulsions

The effect of NaCl and Na₂SO₄ concentrations in aqueous phase on the phase inversion temperature (PIT) in nanoemulsions of water/Brij30/n-hexadecane system has been studied separately, and then compared. The variation of conductivity with temperature was measured by Cyber Scan PC510 conductivity meter for emulsions with 20 wt% hexadecane and 8 wt% Brij30 concentration and different concentrations of NaCl and Na₂SO₄ in aqueous phase. The results showed that with increasing concentrations of NaCl and Na₂SO₄ in aqueous phase, the PIT of nanoemulsions decreases. The effect of the elevation of concentration on the decrease of PIT was more for Na₂SO₄ in aqueous phase than NaCl with equal concentrations.     

Three new [XC(O)NH]P(O)[N(CH2C6H5)2]2 phosphoric triamides (X = CClF2, 3‐F‐C6H4 and 3,5‐F2‐C6H3): a database analysis of tertiary N‐atom geometry in compounds with a C(O)NHP(O)[N]2 core

In the phosphoric triamides N,N,N′,N′‐tetrabenzyl‐N′′‐(2‐chloro‐2,2‐difluoroacetyl)phosphoric triamide, C₃₀H₂₉ClF₂N₃O₂P, (I), N,N,N′,N′‐tetrabenzyl‐N′′‐(3‐fluorobenzoyl)phosphoric triamide, C₃₅H₃₃FN₃O₂P, (II), and N,N,N′,N′‐tetrabenzyl‐N′′‐(3,5‐difluorobenzoyl)phosphoric triamide, C₃₅H₃₂F₂N₃O₂P, (III), the tertiary N atoms of the dibenzylamido groups have sp² character with minimal deviation from planarity. The sums of the three bond angles about the N atoms in (I)–(III) deviate by less than 8° from the planar value of 360°. The geometries of the tertiary N atoms in all phosphoric triamides with C(O)NHP(O)[N]₂ skeletons deposited in the Cambridge Structural Database [CSD; Allen (2002). Acta Cryst. B 58 , 380–388] have been examined and the bond‐angle sums at the two tertiary N atoms (SUM1 and SUM2) and the parameter ΔSUM (= SUM1 − SUM2) considered. It was found that in compounds with a considerable ΔSUM value, the more pyramidal N atoms are usually oriented so that the corresponding lone electron pair is anti with respect to the P=O group. In (I), (II) and (III), the phosphoryl and carbonyl groups, separated by an N atom, are anti with respect to each other. In the C(O)NHP(O) fragment of (I)–(III), the P—N bond is longer and the O—P—N angle is contracted compared with the other two P—N bonds and the O—P—N angles in the molecules. These effects are also seen in analogous compounds deposited in the CSD. Compounds with [C(O)NH]P(O)[N]X (X≠ N), such as compounds with a [C(O)NH]P(O)[N][O] skeleton, have not been considered here. Also, compounds with a [C(O)NH]₂P(O)[N] fragment have not been reported to date. In the crystal structures of all three title compounds, adjacent molecules are linked via pairs of P=O...H—N hydrogen bonds, forming dimers with C_i symmetry.     

The double H‐atom acceptability of the P=O group in new XP(O)(NHCH2C6H4‐2‐Cl)2 phosphoramidates [X = C6H5O– and CF3C(O)NH–]: a database analysis of compounds having a P(O)(NHR) group

In the hydrogen‐bond patterns of phenyl bis(2‐chlorobenzylamido)phosphinate, C₂₀H₁₉Cl₂N₂O₂P, (I), and N,N′‐bis(2‐chlorobenzyl)‐N′′‐(2,2,2‐trifluoroacetyl)phosphoric triamide, C₁₆H₁₅Cl₂F₃N₃O₂P, (II), the O atoms of the related phosphoryl groups act as double H‐atom acceptors, so that the P=O...(H—N)₂ hydrogen bond in (I) and the P=O...(H—N_amide)₂ and C=O...H—N_C(O)NHP(O) hydrogen bonds in (II) are responsible for the aggregation of the molecules in the crystal packing. The presence of a double H‐atom acceptor centre is a result of the involvement of a greater number of H‐atom donor sites with a smaller number of H‐atom acceptor sites in the hydrogen‐bonding interactions. This article also reviews structures having a P(O)NH group, with the aim of finding similar three‐centre hydrogen bonds in the packing of phosphoramidate compounds. This analysis shows that the factors affecting the preference of the above‐mentioned O atom to act as a double H‐atom acceptor are: (i) a higher number of H‐atom donor sites relative to H‐atom acceptor centres in molecules with P(=O)(NH)₃, (N)P(=O)(NH)₂, C(=O)NHP(=O)(NH)₂ and (NH)₂P(=O)OP(=O)(NH)₂ groups, and (ii) the remarkable H‐atom acceptability of this atom relative to the other acceptor centre(s) in molecules containing an OP(=O)(NH)₂ group, with the explanation that the N atom bound to the P atom in almost all of the structures found does not take part in hydrogen bonding as an acceptor. Moreover, the differences in the H‐atom acceptability of the phosphoryl O atom relative to the O atom of the alkoxy or phenoxy groups in amidophosphoric acid esters may be illustrated by considering the molecular packing of compounds having (O)₂P(=O)(NH) and (O)P(=O)(NH)(N)groups, in which the unique N—H unit in the above‐mentioned molecules almost always selects the phosphoryl O atom as a partner in forming hydrogen‐bond interactions. The P atoms in (I) and (II) are in tetrahedral coordination environments, and the phosphoryl and carbonyl groups in (II) are anti with respect to each other (the P and C groups are separated by one N atom). In the crystal structures of (I) and (II), adjacent molecules are linked via the above‐mentioned hydrogen bonds into a linear arrangement parallel to [100] in both cases, in (I) by forming R₂²(8) rings and in (II) through a combination of R₂²(10) and R₂¹(6) rings.     

Numerical solution of Fokker‐Planck equation using the cubic B‐spline scaling functions

In this article a numerical technique is presented for the solution of Fokker‐Planck equation. This method uses the cubic B‐spline scaling functions. The method consists of expanding the required approximate solution as the elements of cubic B‐spline scaling function. Using the operational matrix of derivative, the problem will be reduced to a set of algebraic equations. Some numerical examples are included to demonstrate the validity and applicability of the technique. The method is easy to implement and produces very accurate results. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009     

Effect of temperature on the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions

In this work the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions were measured at 283.1–313.1 K. The expansion factor of polymer chain was calculated by use of the intrinsic viscosities data. The thermodynamic parameters of polymer solution (the entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer–solvent interaction parameter and second osmotic virial coefficient) were evaluated by temperature dependence of polymer chain expansion factor. The obtained thermodynamic parameters indicate that quality of water was decreased for solutions of poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(ethylene oxide)/poly(vinyl pyrrolidone) blends by increasing temperature. Compatibility of poly(ethylene oxide)/poly(vinyl pyrrolidone) blends were explained in terms of difference between experimental and ideal intrinsic viscosity and solvent–polymer interaction parameter. The results indicate that the poly(ethylene glycol)/poly(vinyl pyrrolidone) blends were incompatible.     

The effect of process and structural parameters on the stability,thermo-mechanical and thermal degradation of polymers with hydrocarbon skeleton containing PE,PP, PS,PVC, NR,PBR and SBR

Journal of Thermal Analysis and Calorimetry - Many studies have been done on the stability, thermo-mechanical degradation and pyrolysis of polymers with hydrocarbon skeleton. According to the main...     

A metal–organic framework/polymer derived catalyst containing single-atom nickel species for electrocatalysis

While metal–organic frameworks (MOF) alone offer a wide range of structural tunability, the formation of composites, through the introduction of other non-native species, like polymers, can further broaden their structure/property spectrum. Here we demonstrate that a polymer, placed inside the MOF pores, can support the collapsible MOF and help inhibit the aggregation of nickel during pyrolysis; this leads to the formation of single atom nickel species in the resulting nitrogen doped carbons, and dramatically improves the activity, CO selectivity and stability in electrochemical CO₂ reduction reaction. Considering the vast number of multifarious MOFs and polymers to choose from, we believe this strategy can open up more possibilities in the field of catalyst design, and further contribute to the already expansive set of MOF applications.

A metal–organic framework/polymer derived catalyst containing single-atom nickel species shows good performance for electroreduction of CO₂ to CO.     

Syntheses and Spectroscopic Study of Some New N‐4‐Fluorobenzoyl Phosphoric Triamides; Crystal Structures of 4‐F‐C6H4C(O)N(H)P(O)R2, R = NH‐C(CH3)3, NH‐CH2C6H5, N(CH3)(CH2C6H5)

Some new N‐4‐Fluorobenzoyl phosphoric triamides with formula 4‐F‐C₆H₄C(O)N(H)P(O)X₂, X = NH‐C(CH₃)₃ ( 1 ), NH‐CH₂‐CH=CH₂ ( 2 ), NH‐CH₂C₆H₅ ( 3 ), N(CH₃)(C₆H₅) ( 4 ), NH‐CH(CH₃)(C₆H₅) ( 5 ) were synthesized and characterized by ¹H, ¹³C, ³¹P NMR, IR and Mass spectroscopy and elemental analysis. The structures of compounds 1 , 3 and 4 were investigated by X‐ray crystallography. The P=O and C=O bonds in these compounds are anti. Compounds 1 and 3 form one dimensional polymeric chain produced by intra‐ and intermolecular ‐P=O···H‐N‐ hydrogen bonds. Compound 4 forms only a centrosymmetric dimer in the crystalline lattice via two equal ‐P=O···H‐N‐ hydrogen bonds. ¹H and ¹³C NMR spectra show two series of signals for the two amine groups in compound 1 . This is also observed for the two α‐methylbenzylamine groups in 5 due to the presence of chiral carbon atom in molecule. ¹³C NMR spectrum of compound 4 shows that ²J(P,C_aliphatic) coupling constant for CH₂ group is greater than for CH₃ in agreement with our previous study. Mass spectra of compounds 1 ‐ 3 (containing 4‐F‐C₆H₄C(O)N(H)P(O) moiety) indicate the fragments of amidophosphoric acid and 4‐F‐C₆H₄CN⁺ that formed in a pseudo McLafferty rearrangement pathway. Also, the fragments of aliphatic amines have high intensity in mass spectra.     

Investigation of Cu Doping,Morphology and Annealing Effects on Structural and Optical Properties of ZnO:Dy Nanostructures

Dysprosium (Dy) doped ZnO nanosheets and nanorods were synthesized by hydrothermal method. Effects of Cu doping, morphology and annealing in Oxygen ambient on structural and optical properties of ZnO nanostructures were investigated using X–ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectra (DRS) and photoluminescence (PL) spectroscopy. This study recommends that both of intrinsic and extrinsic defects facilitate energy transfer (ET) from the ZnO host to Dy³⁺ ions and consequently have an effective role on producing intense Dy emissions at indirect excitation. The results also revealed that annealing process improved the crystal structure of ZnO nanorods due to decrease of surface; however decreased ET and Dy emissions because of diminishing in oxygen vacancy. In addition, as a result of increasing of surface area in nanorods compared to nanosheets, the oxygen vacancies and ET were enhanced. Moreover the results exhibited that electrical and optical properties of ZnO:Dy can be tuned by various amount of Dy concentrations and also Cu doping.     

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.