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A new starch-based adhesive with high solid content, high binding force, and low viscosity was prepared via hydrolysis of cassava starch with α-amylase using glycerol as a plasticizer and Ammonium Zirconium Carbonate (AZC) as a crosslinker. The adhesive was applied to coated paper as a partial substitute for SBR latex. The effects of α-amylase, glycerol, AZC, and temperature on the starch adhesive and its performance in application were investigated. The prepared crosslinking cassava starch adhesive showed a significant effect when the starch slurry concentration was 50% (w/w), the dosages of glycerol and α-amylase were 15% and 0.075%, respectively, and the enzymolysis starch was crosslinked with 12% AZC at 50 °C. The modified starch improved the paper in terms of surface strength, gloss, whiteness, and smoothness when 20% SBR latex was substituted into the coating formulation. Statistical analysis indicated that the crosslinking temperature and AZC had significant effects on the performance of the paper, while glycerin and α-amylase had little effect on it. Spectral analysis of the product showed that the crosslinking reaction took place between AZC and cassava starch. The average particle size was 528.6 nm. Scanning Electron Microscope (SEM) images of the paper surface were consistent with the other measured surface properties. [ABSTRACT FROM AUTHOR]

The article discusses the development of a new synthesis that increases the performance of MFI, a zeolite. Researchers have done it through reducing the thickness of the zeolite crystal, thereby decreasing the lengths of the diffusion paths. They used a surfactant containing a quaternary ammonium group at one end to direct the synthesis of MFI. They found that when the zeolite was used to transform methanol into gasoline, the catalytic longevity has greatly increased.

Abstract: In this paper, the APP-modified reconstituted tobacco sheet (RTS) was prepared by a paper-making process. Thermogravimetric analysis coupled to Fourier transform infrared spectrometer (TG-FTIR) had been used to investigate the influences of APP on the thermal degradation and the formation of evolved volatile products of RTS. TG-FTIR results illustrated that the incorporation of APP into RTS could retard the thermal degradation of the major components of RTS and meanwhile lead to the formation of more thermally stable char. Moreover, the main gases released during the pyrolysis of RTS and APP-modified RTS were H2O, CO2, CO, NH3, carbonyl compounds, alcohols and alkanes. The presence of APP changed the formation of evolved volatile products of RTS obviously. The effects of APP on the combustion behavior of RTS were studied by micro-scale combustion calorimetry (MCC), cone calorimetry (CCO) and infrared thermography (IRT). Results demonstrated that the formation of combustible gases was mainly determined by the thermal decomposition stage occurred in the temperature range of 150–600°C. The incorporation of APP into RTS influenced the release of fuel gases and the char formation in the process of the thermal decomposition of RTS, and eventually retarded the flammability of RTS. In addition, it had been found that the maximum firecone temperature of untreated RTS was higher than that of APP-modified RTS. [Copyright &y& Elsevier]

In this paper, we report an easy route for preparing new metal nanorod-polymer composites consisting of gold nanorods, Au NRs, and temperature responsive copolymer "microgel" particles. The microgel particles of ~200 nm in size, which contain carboxylic acid groups, were prepared by surfactant-free emulsion polymerization of a selected mixture made of N-isopropylacylamide and acrylic acid in the presence of a cross-linker N,N0-methylenebisacrylamide. The electrostatic interactions between the cationic cetyltrimethylammonium bromide (CTAB) stabilized Au NRs and anionic microgel particles were expected to occur in order to prepare stable Au NRs-microgel composite particles. The optical and structural characterization of the composite was achieved using UV-Vis spectroscopy, Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM) and dynamic light scattering (DLS). TEM image shows that Au NRs are attached on the surface of the microgel particles. Dynamic light scattering measurements prove that the composite particles are temperature responsive, which means the particles undergo a decrease in size as the temperature increases above its phase transition temperature. In vitro cytotoxicity of the composite materials were tested by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Lactate dehydrogenase (LDH), and hemolysis assay, which showed non-toxicity (biocompatibility). [ABSTRACT FROM AUTHOR]

This paper collects experimental data and mathematical modelling of Nd(III), Tb(III) and Dy(III) solvent extraction with an ionic liquid prepared from Aliquat 336 (Methyl-tri(octyl/decyl)ammonium chloride) and Oleic Acid (AliOle). Extraction experiments were carried out to evaluate the effect of chloride anion in aqueous phase, AliOle and REE concentrations over the extraction extension. Mathematical models computed with Matlab software were derived from the mass balances and chemical equilibria involved in the extraction system of Neodymium(III), Terbium(III) and Dysprosium(III) individually. The optimized equilibria parameters proposed fit accurately the experimental data and allowed us to predict the extraction extension of each metal from an aqueous mixture. [ABSTRACT FROM AUTHOR]

The synthesis of mono-sized silica nanoparticle with mesostructures via sol-gel method by employing ammonium polycarboxylate (APC) surfactant has investigated. The major aim of this paper is to introduce APC as an appropriate surfactant to control nucleation and growth of nanoparticles during hydration and condensation steps of the sol-gel process. Dynamic light scattering (DLS) results indicated that the particle in the sol containing APC had an average particle size about 10 nm. The bonds of prepared silica nanoparticles were studied by IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The result of scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) confirmed that applying APC could sufficiently induce the mass transfer during the synthesis process, this claim have also verified according to the particle size analysis. Resulting information also approved the synthesis of spherical and mono-sized nanoparticle with an average particle size of 25 nm. Furthermore, the synthesized nanoparticles possessed a mesostructured characteristic due to leaving of APC organic components during final heat treatment. N 2 adsorption/desorption porosimetry indicated that the particles were comprised of mesopores with an average pore size of 2.5 nm and specific surface area of 1015 m 2 g −1 . This strategy could be readily applied to prepare an engineered product of silica nanoparticles with uniform spherical morphology and mesostructure. [ABSTRACT FROM AUTHOR]

This paper reports the phase equilibrium temperature and dissociation heat of ionic semiclathrate hydrate formed with tetrabutylammonium butyrate (TBABu). The temperature – composition phase diagram of the TBABu hydrate was determined in the mass fraction from 0.10 to 0.44. The highest equilibrium temperature of TBABu hydrate was 15.4 °C in the mass fraction range from 0.35 to 0.37. On the dissociation heat of DSC measurements, a single heat flow peak of TBABu hydrate excluding ice melting peak was observed at all the mass fraction systems. The largest dissociation heat was 184.9 ± 3.1 kJ/kg at the mass fraction 0.36. TBABu hydrate could potentially be used as a thermal energy storage material. [ABSTRACT FROM AUTHOR]

The paper presents a technique for the synthesis of molybdenum carbide using mechanical activation of carbon black, which was impregnated with a 20% aqueous solution of ammonium heptamolybdate (AHM) using the incipient wetness technique, in an inert medium at a 100 g acceleration of milling bodies for 30 min. The mechanically activated carbide-containing composites were calcined in an inert medium at 800 °C. The composites were examined by a range of physical methods. It was shown that the mechanically activated composite consists of molybdenum carbide, iron oxide and iron carbide (about 4–8% according to AES-ICP). The phase addition method was used to determine the quantitative content of Мо 2 С, which was equal to 7.2 wt% in the calcined sample. Catalytic testing of mechanically activated molybdenum carbide in the partial oxidation of methane showed that the carbide-containing catalyst provides a 48–60% conversion of methane and an 83–85% selectivity for the target product (CO). [ABSTRACT FROM AUTHOR]

In this paper the interfacial behavior of aqueous solutions of cationic gemini surfactants of the, N,N′-bis(dimethylalkyl)-α,ω-alkanediammoniumdibromide type (known as the 12-s-12 series), in the absence and presence of ZnO nanoparticles was studied. Equilibrium and dynamic interfacial tension between n- decane and aqueous surfactant solutions were investigated. It was concluded that the synergistic effect between surfactants and nanoparticles increases the surfactant efficiency with respect to reducing the interfacial tension. Moreover, the magnitude of the effect of ZnO nanoparticles on the interfacial tension decreases with increasing length of the spacer group in the gemini surfactant structure. Dynamic studies illustrate that the migration mechanism of gemini surfactants (regardless of the presence of ZnO) from the bulk to the interface was controlled by both diffusion and adsorption. The effect of spacer length on the contact angle and emulsion stability both with and without nanoparticles was also studied. [ABSTRACT FROM AUTHOR]

This paper presents the preparation of γ-MnS thin films from three different chemical baths having the chemicals manganese acetate, triethylamine, ammonium chloride, hydrazine hydrate and thioacetamide. The preparative parameters were optimized to obtain good quality MnS thin films. The reaction of formation of MnS was discussed in this paper. XRD analysis is employed to confirm the structure and nature of γ-MnS thin films. The calculated crystallite size ranges from 40-54 nm, indicating that the as-prepared MnS films are made up of nanocrystals. EDAX spectra enabled to identify the film as Mn1.2S0.8. SEM pictures showed the hollow spherical morphology of the prepared γ-MnS thin films. FTIR spectra of γ-MnS thin films have also been analyzed and discussed in this paper. [ABSTRACT FROM AUTHOR]

Abstract: The effect of surfactants sodium dodecyl sulphate (SDS) and cetyltrimethyl ammonium bromide (CTAB) on the surface roughness, surface morphology and surface topography of electroless nickel (EN)–phosphorus surface protective coating obtained from an alkaline bath is presented in this paper. In this study the influence of surfactant concentrations on the surface roughness of coated samples were investigated. It was observed that the surface roughness, surface morphology and surface topography of Ni–P coating were clearly influenced by the addition of surfactants SDS and CTAB. EN deposits with addition of surfactant SDS and CTAB at a concentration of 0.6g/l produce a smooth surface and the average roughness (R a) value is 1.715μm for SDS and 1.607μm for CTAB which is less than the R a value of EN deposit without surfactant addition (1.885μm). The mean average roughness (R a) value with addition of surfactant is 1.796μm. EN deposit with addition of surfactants consists of a significant fraction of particles of nickel. In the presence of SDS, fine nickel particles have dispersed uniformly on the substrate surface resulting in smoother surface finish of the deposited layers. In the presence of CTAB, at lower concentrations (upto 0.6g/l) coalescence of nickel particles have been deposited on the substrate surface and at the higher concentration (above 0.6g/l) uniformly improved surface finish of the deposited layer is resulted. The complete experimental details, results obtained and their analysis are presented in this paper. [Copyright &y& Elsevier]

In this paper we report the synthesis, the crystal structure and the optical response of APbX 3 (A=MA, DMA, and TMA; X=I, Br) hybrid organic-inorganic materials including some new phases. We observe that as the cation group increases in size, the optical absorption edge shifts to higher energies with energy steps which are systematic and independent on the anion. A linear correlation between the optical bad gap and the tolerance factor has been shown for the series of samples investigated. [ABSTRACT FROM AUTHOR]

This paper reports the solvothermal synthesis of MoS nanospheres and nanosheets. The nanospheres were obtained using ammonium polysulfide as a sulfur source and have a mean diameter of about 100 nm. The nanosheets were assembled from a few lamellar layers and were obtained using thiourea as a sulfur source. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used in order to characterize the prepared powders. Conglomerate size and stability of the synthesized samples in hexane were studied with zeta potential. The four-ball method was used to assess the lubricating effect when these materials were used as additives in engine oil dispersions. The topography of the wear scar was analyzed using SEM, EDX, and 3D surface profilometry. The tribological properties of base engine oil containing the nanomaterials penetrated more easily into the interface space, and it formed a tribo-film at contact interface. The tribological performance showed that the synthesized nanosheets had superior anti-wear and friction-reducing properties as a lubrication additive compared with nanospheres, and the wear scar of balls lubricated with nanospheres revealed larger width compared to nanosheets. From the results, it is observed that nanosheets dispensed in oil have better tribological performance compared to nanospheres oil in terms of capability to reduce wear. [ABSTRACT FROM AUTHOR]

The homogeneous catalytic oxidation of ammonium sulfite in a microporous tube-in-tube microchannel reactor (MTMCR) was studied in this paper. It was found that the oxidation rate of ammonium sulfite in the MTMCR is 360 times higher than that in a packing column and could be further boosted about 4-6 times by the Co2+ catalyst. The effects of different operating parameters on the oxidation of ammonium sulfite were investigated. Experimental results indicated that the oxidation ratio of ammonium sulfite increased with the increase of the oxygen volumetric flow rate, but decreased with the increase of the liquid volumetric flow rate and sulfite concentration, and a smaller micropore size and annular channel width resulted in a higher oxidation ratio of ammonium sulfite. The oxidation ratio reached 80% under the optimum operating conditions in the catalytic oxidation process. This study reveals that the MTMCR is a potential intensification device for the oxidation process of ammonium sulfite. [ABSTRACT FROM AUTHOR]

Abstract: In the present paper, a study on the influence of the alkyl chain length in N-alkyl-triethylammonium bis(trifluoromethylsulfonyl)imide ionic liquids, [N R,222][Tf2N] (R =6, 8 or 12), on the excess molar enthalpy at 303.15K and excess molar volume within the temperature interval (283.15–338.15K) of ionic liquid+methanol mixtures is carried out. Small excess molar volumes with highly asymmetric curves (i.e. S-shape) as a function of mole fraction composition were obtained, with negative values showing in the methanol-rich regions. The excess molar volumes increase with the increase of the alkyl-chain length of the ammonium cation of the ionic liquid and decrease with temperature. The excess enthalpies of selected binary mixtures are positive over the whole composition range and increase slightly with the length of the alkyl side-chain of the cation on the ionic liquid. Both excess properties were subsequently correlated using a Redlich–Kister-type equation, as well as by using the ERAS model. From this semipredictive model the studied excess quantities could be obtained from its chemical and physical contribution. Finally, the COSMOThermX software has been used to evaluate its prediction capability on the excess enthalpy for investigated mixtures at 303.15K and 0.1MPa. From this work, it appears that COSMOThermX method predicts this property with good accuracy of approx. 10%, providing at the same time the correct order of magnitude of the partial molar excess enthalpies at infinite dilution for the studied ILs, , and methanol, . [Copyright &y& Elsevier]

In this paper, we have examined the conductivity and interaction studies of ammonium and imidazolium based ionic liquids (ILs) with the newly synthesised low bandgap polymer (Poly(2-heptadecyl-4-vinylthieno[3,4-d]thiazole) (PHVTT)). Use of low bandgap polymers is the most suitable way to harvest a broader spectrum of solar radiations for solar cells. But, still there is lack of most efficient low bandgap polymer. In order to solve this problem, we have synthesised a new low bandgap polymer and investigated its interaction with the ILs to enhance its conductivity. ILs may undergo almost unlimited structural variations; these structural variations have attracted extensive attention in polymer studies. The aim of present work is to illustrate the state of art progress of implementing the interaction of ILs (protic and aprotic ILs) with newly synthesised low bandgap polymer. In addition to this, our UV-Vis spectroscopy, confocal Raman spectroscopy and FT-IR spectroscopy results have revealed that all studied ILs (tributylmethylammonium methyl sulfate ([N1444][MeSO4] from ammonium family) and 1-methylimidazolium chloride ([Mim]Cl, and 1-butyl-3-methylimidazolium chloride ([Bmim]Cl from imidazolium family) have potential to interact with polymer. Our semi empirical calculation with help of Hyperchem 7 shows that protic IL ([Mim]Cl) interacts strongly with the low bandgap polymer through the H-bonding. Further, protic ILs shows enhanced conductivity than aprotic ILs in association with low bandgap polymer. This study provides the combined effect of low bandgap polymer and ILs that may generate many theoretical and experimental opportunities. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we have studied and analyzed the capabilities and limitations of seven stochastic global optimization methods to model mean activity coefficients of ammonium aqueous electrolytes using the electrolyte NRTL model. These stochastic methods are: simulated annealing (SA), genetic algorithm (GA), differential evolution (DE), particle swarm optimization (PSO), DE with tabu list (DETL), harmony search (HS) and bare bones PSO (BBPSO). Convergence characteristics and performances of these optimization methods have been tested and compared using different stopping conditions. Overall, our results indicate that SA, DETL and BBPSO offer better performance and promising convergence characteristics for solving parameter estimation problems involved in the modeling of thermodynamic properties of ionic liquids (ILs). [Copyright &y& Elsevier]

This paper reports on the synthesis of a new hydroxylammonium fluoroferrate, with the formula (NH3OH)3FeF6, obtained after dissolving iron powder in hydrofluoric acid and adding solid NH3OHF. This new compound has been characterized by chemical and thermal analysis, single-crystal X-ray diffraction, and magnetic measurements. The title compound crystallizes trigonal, R3c, with cell parameters a = 11.4154(2) Å, c = 11.5720(2) Å, Z = 6. The structure consists of NH3OH+ cations and isolated FeF663- octahedra in which the central ion lies on a threefold axis. The oxygen and nitrogen atoms of the hydroxylammonium cations are donors of hydrogen bonds to fluoride anions, resulting in a network of hydrogen bonds between counterions. The effective magnetic moment μeff = 5.8 BM was calculated and perfectly matches the expected value of high-spin Fe(III) ions. The thermal decomposition of the compound was studied by TG, DSC, and X-ray powder diffraction. [ABSTRACT FROM AUTHOR]

Abstract: Cationic gemini surfactant homologues alkanediyl-α,ω-bis(dodecyldiethylammonium bromide), [C12H25(CH3CH2)2N(CH2)SN(CH2CH3)2C12H25]Br2 (where S =2, 4, 6, 8, 10, 12, 16, 20), referred to as C12CSC12(Et) were synthesized systematically. This paper focused on various properties of the above gemini surfactants in order to give a full understanding of this series of surfactants. The following points are covered: (1) surface properties, which include (i) effect of the spacer carbon number on the general properties and (ii) the effect of added NaBr on the general surface properties; (2) aggregation behavior in bulk solution, including (i) morphologies of above gemini surfactants classed as having short spacers, middle-length spacers and long spacers and (ii) superior vesicle stability against high NaBr concentration for the long spacer gemini surfactants; (3) thermodynamic properties during micellization and the effect of spacer carbon number on them; and (4) perspectives for the further use and application of these compounds. [Copyright &y& Elsevier]

7-Aminocephalosporanic acid wastewater usually contains high concentrations of ammonium (NH4 +-N), which is known to inhibit nitrification during biological treatment processes. Chemical precipitation is a useful technology to remove ammonium from wastewater. In this paper, the removal of ammonium from 7-aminocephalosporanic acid wastewater was studied. The optimum pH, molar ratio, and various chemical compositions of magnesium ammonium phosphate (MAP) precipitation were investigated. The results indicated that ammonium in 7-aminocephalosporanic acid wastewater could be removed at an optimum pH of 9. The Mg2+:NH4+-N:PO43--P molar ratio was readily controlled at a ratio of 1:1:1.1 to both effectively remove ammonium and avoid creating a higher concentration of PO43--P in the effluent. MgCl2·6H2O + 85% H3PO4 was the most efficient combination for NH4+-N removal. Furthermore, the lowest concentration of the residual PO43--P was obtained with the same combination. Struvite precipitation could be considered an effective technology for the NH4+-N removal from the 7-aminocephalosporanic acid wastewater. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes the measuring procedure which enables overcoming the base difficulty in application of the vibrating plate (VP) technique to measuring electric surface potential (ΔV) of free solution surfaces, namely loosing the zero level set for the reference sample (water) while replacing it with the solution measured. (The ΔV measurement is performed by comparing two measurements in series, i.e., for the pure interface and that containing a surface film.) Main improvement in the measuring procedure is achieved by (i) applying a flow for exchanging the reference sample with the measured solution and (ii) elimination of an error driven by dependency of the measuring signal on the air gap width. The air gap width is fixed by contact of the bottom edge of a platinum Wilhelmy plate with the solution surface which the plate is simultaneously used for measurement of the surface pressure (Π). The results received with the new methodology for n-decanoic acid, n-decyl-trimethylammonium bromide (C10TABr) and sodium n-dodecyl sulphate (SLS) are discussed. [Copyright &y& Elsevier]

Abstract: This paper reports the investigation about the effect of the alkyl tail length of quaternary gemini surfactants, 2-hydroxyl-propanediyl-α,ω-bis(dimethylalkylammonium bromide), referred to as m-3(OH)-m, where m represents the number of carbon atoms at each alkyl tail, on the foamability and foam stability. To understand the foaming behavior, the adsorption of surfactants at the air/water interface as well as the dilational viscoelasticity of their films was studied using surface tension and dilational interfacial rheology measurements. 14-3(OH)-14 was found to have stronger foamability and stabilize more efficiently the foam than 12-3(OH)-12, however, 16-3(OH)-16 failed to generate foam. The latter was attributed to the self-coiling of the long hexadecyl tails prior to the adsorption of surfactant at the air/water interface, resulting in the ageing effect of the adsorption behavior. For both 12-3(OH)-12 and 14-3(OH)-14, the results revealed a good correlation between the high limit interfacial elasticity and high stability of foam at the level of identical surface excesses. [Copyright &y& Elsevier]

Abstract: Antibacterial agents receive a great deal of attention around the world due to the interesting academic problems of how to combat bacteria and of the beneficial health, social and economic effects of successful agents. Scientists are actively developing new antibacterial agents for biomaterial applications. This paper reports the novel antibacterial agent siloxane sulfopropylbetaine (SSPB), which contains reactive alkoxysilane groups. The structure and properties of SSPB were systematically investigated, with the results showing that SSPB contains both quaternary ammonium compounds and reactive siloxane groups. SSPB has good antibacterial activity against both Escherichia coli (E. coli, 8099) and Staphylococcus aureus (S. aureus, ATCC 6538). The minimal inhibition concentration is 70μmol/ml SSPB against both E. coli and S. aureus. In addition, the SSPB antibacterial agent can be used in both weak acid and weak alkaline environments, functioning within the wide pH range of 4.0–9.0. The SSPB-modified glass surface killed 99.96% of both S. aureus and E. coli organisms within 24h. No significant decrease was observed in this antibacterial activity after 20 washes. Moreover, SSPB does not induce a skin reaction and is nontoxic to animals. Thus, SSPB is an ideal candidate for future applications as a safe, environmentally friendly antibacterial agent. [Copyright &y& Elsevier]

Abstract: This paper addresses the identification of (E)-5-formyl-2,3,3′,4′-tetramethoxystilbene (11), a major tetramethylammonium hydroxide (TMAH) thermochemolysis product of guaiacyl dehydrogenation polymer (DHP). It was carried out by comparing the mass spectral data and chromatographic behavior with those of authentic (E)-11, which was prepared by off-line preparative TMAH thermochemolysis of 3-[2-(4-hydroxy-3-methoxyphenyl)-3-hydroxymethyl-7-methoxy-2,3-dihydrobenzo[b]furan-5-yl]prop-2-enal (14). As the origins of 11, internal β-5 subunits III connected with other subunits by β-O-4 linkages at both sides via the phenolic and β-alcoholic hydroxyl groups, and phenolic β-5 subunits IV connected with other subunits by β-O-4 linkages at one side via the β-alcoholic hydroxyl group were proposed. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the interaction between three water soluble conjugated polymers: sodium poly{9,9-bis[(4-butylsulfonate)phenoxy]-2,7-fluorene-alt-1,4-phenylene} (PBS-PFP), poly{9,9-bis[(6′-N,N,N-trimethylammonium) hexyl]-2,7-fluorene-alt-1,4-phenylene} dibromide (HTMA-PFP) and poly{9,9′-bis[(6″-N-acetyltyrosine)hexyl]-2,7-fluorene-alt-1,4-phenylene}, (Tyr–PFP) with neutral and charged surfactants has been studied. The optical spectroscopic properties of the three polymers in aqueous solution (PBS-PFP) and in DMSO–water mixtures (4% v/v, HTMA-PFP and Tyr–PFP) are also presented. Three different biocompatible surfactants were used: a single chain one, N α -lauroyl-l-arginine methyl ester hydrochloride (LAM), a gemini compound, N α ,N ω -bis(N α lauroylarginine) α, ω-dibutylamide dihydrochloride, (C4(LA)2) and an amino acid glyceride conjugate, 1-O-(l-arginyl)-2,3-O-di-lauroyl-sn-glycerol dichlorhydrate (1212R). In addition, the interaction of the same polymers with three commonly used commercial non-ionic surfactants: n-dodecyl pentaoxyethylene glycol ether (C12E5), 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton X-100) and polyethylene glycol sorbitan monolaurate (Tween 20) was also studied. Electronic spectroscopy (absorption and steady-state emission) as well as molecular dynamics using the Gromacs package (for the interaction between HTMA-PFP and Triton X-100) and ionic conductivity measurements on HTMA-PFP/C12E5 are also reported. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we report the effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) in the oxidation of valine by permanganate in the absence and presence of sulphuric acid media. The reaction follows fractional- and first-order kinetics with respect to [valine] and [H2SO4] in the presence of CTAB whereas [H2SO4] has no effect on the reaction rate in the absence of CTAB under our experimental conditions. The observed catalytic effect of CTAB is discussed in terms of penetration of non-polar side chain of valine into the palisade layer of CTAB micelles through hydrophobic interactions. The Menger and Portony model of micelles and the model modified by Bunton''s group have been used to explain the catalytic role of CTAB. On the basis of various observations, the most plausible mechanism is proposed and discussed. [Copyright &y& Elsevier]

Abstract: The paper presents the influence of the dynamic adsorption layer (DAL) formation on time of the bubble attachment to mica surface in n-dodecyltrimethylammonium bromide (DDTABr) and n-hexadecyltrimethylammonium bromide (CTABr) solutions. Phenomena occurring during collisions of the single rising bubbles with mica plates, located at different distances (“close” and “far”) from the point of the bubble detachment, were monitored using high-speed camera. It was found that when the distance from the capillary to the mica plate was L =3mm (location “close”) then the time of the three-phase contact formation (t TPC), was significantly shorter than for the location “far” (L =100mm). The differences between the t TPC for the locations “close” and “far” were the largest at lowest concentration. For example in 1×10−6 M CTABr solution the t TPC was 162±97ms for L =3mm and was prolonged to 578±121ms for L =100mm. Similarly, in 1×10−6 M DDTABr solution the t TPC was 543±79 and 1840±440ms for L =3 and 100mm, respectively. Longer the t TPC values at the mica location “far” were attributed to the formation of the dynamic adsorption layer (DAL), with the top pole of the rising bubble almost devoid of the adsorbed cationic surfactants. The bubble attachment to mica was due to the electric charge reversal by the cationic surfactant molecules adsorbed at the bubble surface, which led to the wetting film rupture due to electrostatic attractive interactions between oppositely charged interacting interfaces. Therefore, at the location “far” the time of the TPC formation (t TPC “far”) was longer because there was needed an additional time to restore such degree of cationic surfactant coverage at the bubble top pole, which caused the electric charge reversal from negative to positive. It was showed that the adsorption coverages needed for the electric charge reversal at the liquid gas interface can be restored during the Δt TPC = t TPC “far” − t TPC “close” time intervals. [Copyright &y& Elsevier]

Abstract: This paper proposes a methodology based on electrochemical reduction for a fast, specific and sensitive determination of genistein by square-wave voltammetry (SWV). The highest peak currents and optimal definition of reduction peak of genistein was obtained by using a supporting electrolyte consisted of 0.04molL−1 phosphate buffer–methanol (8:2, v/v) solution at pH 7.5 and cationic surfactant 2.21×10−4 molL−1 cetyltrimethylammonium bromide (CTAB). The peak current was proportional to the concentration of genistein in the range 1.14×10−7 to 1.09×10−6 molL−1, with a detection limit and quantification of 3.43×10−8 molL−1 and 1.14×10−7 molL−1, respectively. The extraction procedure was evaluated for a better determination of genistein contained in soy flour and soy based supplements. The efficiency of the proposed methodology was demonstrated by comparing the results obtained by SWV with those obtained by the high-performance liquid chromatography (HPLC) method. [Copyright &y& Elsevier]

Abstract: In this paper were analyzed the surface properties of surfactants and the miscibility and interactions between components of adsorbed monolayers and micelles formed from mixed systems. The investigated compounds differ in the structure of the polar head and represented cationic (dodecyltrihydroxyethylammonium bromide—DTEAB, dodecyltrimethylammonium bromide DTMAB), anionic (sodium dodecyl sulfate—SDS), and nonionic (dodecyl-β-d-glucoside—DG) surfactant. The experiments were based on the measurements of the surface tension of the aqueous solutions of the investigated compounds and their mixtures (cationic/nonionic—DTEAB/DG, cationic/cationic—DTEAB/DTMAB and cationic/anionic—DTEAB/SDS). The composition of the mixed films and micelles as well as the free energies of mixing values, which are a measure of the molecular interactions, was calculated basing on the equations resulting from the Motomura theory. The obtained results indicate that all the investigated systems mix nonideally both in the monolayers and micelles. The magnitude of the deviations from ideal behavior is strongly dependent on the type of the investigated mixture and increases in the following order: DTEAB/DTMAB < DTEAB/DG ≪ DTEAB/SDS. [Copyright &y& Elsevier]

In this paper, a software sensor based on a fuzzy neural network (FNN) approach was proposed for the real-time estimation of nutrient concentrations and overcoming the problem of delayed measure- ments. To improve the FNN performance, fuzzy subtractive clustering was used to identify the model's architecture and optimize the fuzzy rule; meanwhile, a split network structure, applied separately for anaerobic and aerobic conditions, was used with dynamic modeling methods, such as an auto-regressive model with exogenous inputs. The proposed methodology was applied to a bench-scale anoxic/oxic process for biological nitrogen removal. It was possible to partially overcome the extrapolation problem of FNNs with the aid of multi-way principal component analysis, because it has the ability to detect abnormal situations, which could generate extrapolation. Real-time estimation of chemical oxygen demand, nitrate, and ammonium concentrations based on the model was successfully carried out with the simple online information of the anoxic/oxic system. Water Environ. Res., 81, 654 (2009). [ABSTRACT FROM AUTHOR]

Plant-available P was first extracted in soils 114 years ago and a number of different analytical methods have since been developed, but for good reasons none of these methods has been adopted as a standard for all soils. With increasing cooperation within research, there is a need to harmonise the interpretation of analytical data for fertiliser recommendations, research, and environmental control. This paper evaluates the compatibility of the Swedish standard ammonium lactate (PAL) method and the widely used Olson's sodium bicarbonate (POls) method in 82 topsoil samples taken from Swedish long-term soil fertility field trials. The PAL-values were usually larger than POls, with a mean PAL/POls quotient of 2.30±1.04 (0.67-6.58). The PAL and POls means and ranges were 126±89 (5-360) and 55.1±33 (3.1-122.8) mg P kg-1 dry soil, respectively. Stepwise multiple linear regression analysis was used to evaluate the relationship between PAL and POls and how this relationship was affected by clay content, pH, and soil organic carbon content (SOC). After statistical transformation, it emerged that the square root of clay content (17.4%±13.82, range 1-54.4) and pH (6.45±0.54, range 5.5-7.7) significantly affected the relationship at partial R 2-values of 2 and 12%, respectively, while ln(SOC) (2.54%±1.21, range 1-6.03) did not, apparently due the narrow range. The regressions of predicted vs. measured values explained 95 and 94% of the variation in PAL and POls, respectively. The mean deviation of predicted compared with measured values was 21.3 and 8.3 mg P kg-1 dry soil for PAL and POls, respectively, corresponding to 20 or 19% of the measured values. We conclude that a data set consisting of PAL-values can be converted into POls-values and vice versa with reasonably high accuracy when accounting for clay content and pH. [ABSTRACT FROM AUTHOR]

Abstract: Holographic measurements have shown that the addition of 0.5% of poly(acrylic acid) (PAA) can improve the quality of holograms recorded in poly(vinyl alcohol) (PVA) doped with ammonium dichromate (ADC). The purpose of this paper is to explain this improvement. First, an analytical approach investigated the structural and architectural modification of the polymeric matrix and the fate of the various chromium species within PVA/PAA/ADC films. The addition of PAA in dichromated PVA led to a pre-reticulation of the polymeric matrix. This process increased with the amount of PAA. Second, an analytical approach focused on the evolution of PVA/PAA/ADC films upon irradiation at 365nm, which is representative of hologram formation. The improvement brought by the presence of 0.5% of PAA in PVA/ADC was assigned to an additional source of crosslinking through the formation of covalent bonds. This process paralleled the crosslinking through coordination bonds involving Cr(V) and PVA units. At 0.5% of PAA, the mobility of the medium before exposure was sufficient to allow the migration of the species involved in the reticulation process during hologram formation, whereas higher concentrations of PAA inhibited this migration. [Copyright &y& Elsevier]

Earlier, we have published a paper on the preparation of silica sphere using propanol as cosurfactant.We report here a highly costeffective method of preparation of mesoporous silica spheres with core shell structure using sodium silicate as silica precursor, cetyltrimethyl ammonium bromide (CTAB) as surfactant, and methanol as cosurfactant. Thus after removal of the template by dissolutions or/and activation at higher temperature, mesoporous silica spheres with core shell structure were obtained. The products prepared with methanol to CTAB molar ratio 8.5 : 1 were confirmed to give best results. All the spherical products have very large surface area (~589-1044m2/g), pore volume (~0.98-1.41 cm3/g), and ordered pore structure. [ABSTRACT FROM AUTHOR]

The chemical transformation of ammonium cyanate into urea has been of interest to many generations of scientists since its discovery by Friedrich Wöhler in 1828. Although widely studied both experimentally and theoretically, several mechanistic aspects of this reaction remain to be understood. In this paper, we apply computational methods to investigate the behavior of ammonium cyanate in the solid state under high pressure, employing a theoretical approach based on the self-consistent-charges density-functional tight-binding method (SCC-DFTB). The ammonium cyanate crystal structure was relaxed under external pressure ranging from 0 to 700 GPa, leading to the identification of five structural phases. Significantly, the phase at highest pressure (above 535 GPa) corresponds to the formation of urea molecules. At ca.25 GPa, there is a phase transition of ammonium cyanate (from tetragonal P4/nmmto monoclinic P21/m) involving a rearrangement of the ammonium cyanate molecules. This transformation is critical for the subsequent transformation to urea. The crystalline phase of urea obtained above 535 GPa also has P21/msymmetry (Z2). This polymorph of urea has never been reported previously. Comparisons to the known (tetragonal) polymorph of urea found experimentally at ambient pressure suggests that the new polymorph is more stable above ca. 8 GPa. Our computational studies show that the transformation of ammonium cyanate into urea is strongly exothermic (enthalpy change −170 kJ mol-1per formula unit between 530 and 535 GPa). The proposed mechanism for this transformation involves the transfer of two hydrogen atoms of the ammonium cation toward nitrogen atoms of neighboring cyanate anions, and the remaining NH2group creates a C−NH2bond with the cyanate unit. [ABSTRACT FROM AUTHOR]

Despite of the fact that copper-ethanolamine based aqueous solutions have been used for wood preservation for almost two decades, the complete mechanism of Cu-ethanolamine fixation is not completely understood. In order to elucidate interactions between copper-ethanolamine aqueous solutions and wood, Norway spruce (Picea abies) sawdust was immersed to 19 different copper based formulations. These solutions besides copper(II) sulphate contains ethanolamine and quaternary ammonium compound, sodium borate and/or octanoic acid. pH of this mixture was monitored for 4 h. Immersed sawdust was put to filter paper and washed with 1 L of distilled water. Leached impregnated wood sawdust was than oven dried (103 °C) and kept in dark and dry place until copper and nitrogen content were determined and correlated to pH changes of sawdust-preservative suspension during impregnation. The result showed that presence of ethanolamine makes fixation of copper in wood more effective. Copper absorption to sawdust is affected by concentration of copper, pH of the preservative solution and correlates with pH decrease during impregnation well. Furthermore, we proved that copper and nitrogen absorption to Norway spruce wood are connected as well. Understanding of this mechanism will enable experts to develop preservatives with better performance against weathering and wood pests. [ABSTRACT FROM AUTHOR]

This paper reports the successful design of a prototype of an optical biochemical sensor for the determination of hydroperoxides in nonpolar organic liquids. The sensor consists of a matrix of an amphiphilic polymer conetwork (APCN), a novel class of very promising polymeric materials for easy preparation of biochemical sensor matrices. APCNs are characterised by nanoscopic phase separation between the hydrophilic and the hydrophobic phases. For medium ratios of conetwork composition, the domains of both phases are interconnected both on the surface of the conetworks and throughout the bulk. The APCNs have peculiar swelling properties—the hydrophilic phase swells in hydrophilic media and the hydrophobic phase swells in hydrophobic media. In both types of media dissolved reagents can diffuse from the solution into the swollen phase of the polymeric conetwork. This enables loading of the hydrophilic phase of the APCNs with enzymes and indicator reagents by simple impregnation. Hydrophobic analytes can diffuse into the polymeric conetwork via its hydrophobic phase and react with indicator reagents immobilised in the hydrophilic phase at the huge internal interface between the two opposite phases. To prepare the described hydroperoxide-sensitive biosensors, we used APCN films consisting of 58% ( w/ w) poly(2-hydroxyethyl acrylate) (PHEA) as hydrophilic chains and 42% ( w/ w) polydimethylsiloxane (PDMS) as hydrophobic linkers. Horseradish peroxidase (HRP) and diammonium 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as indicator reagent were co-immobilised in this optically clear and transparent matrix. In this feasibility study the conditions investigated were principally those relevant to characterisation of the innovative matrix material and the disposable biosensor produced from it; the biosensor was not optimised. Sensitivity toward tert-butylhydroperoxide ( tBuOOH) dissolved in n-heptane was acceptable, between approximately 1 and at least 50 mmol L−1, even in the dry state. The response time was 1.7 to 5.0 min. No leaching of immobilised reagents was observed during a period of at least one hour. Pre-swelling the sensors with water increased the reaction rate and the total turnover number of the enzyme. In a dry atmosphere at 4 °C the sensors were found to be stable for at least two weeks. [ABSTRACT FROM AUTHOR]

In the present paper, the tracking phenomena of silicone rubber material has been studied under ac voltages, with ammonium chloride as a contaminant. The characteristic changes in the tracking time of the aged specimens are analyzed through leakage current measurement. The observed trends in the leakage current during the tracking study are analyzed using a moving average current technique. The contact angle of the specimen varies with the type of aging. multiresolution signal decomposition technique was adopted to identify the characteristic change in the hydrophobicity levels of the specimens using the standard deviation multiresolution analysis curve. It is concluded that the material with less contact angle where the leakage current magnitude is high, allows tracking to occur early. [ABSTRACT FROM AUTHOR]

Recently, a population of nerves has been described in the aganglionic mouse vas deferens, in which electrically evoked contractions were insensitive to high concentrations of the adrenergic neurone blocker, bretylium. In this paper, the pharmacology of this nerve-evoked contraction has been examined in more detail.Bretylium (20 μM) revealed, after 5 h exposure, a new residual neurogenic contraction (20 stimuli at 10 Hz) that was tetrodotoxin-sensitive.The muscarinic antagonist, cyclopentolate (0.1 and 1 μM), reduced this residual component and the inhibition was reversed by the acetylcholinesterase inhibitor, neostigmine (1 and 10 μM).Nicotine (30 μM) enhanced the residual component revealed by bretylium, suggesting that there are prejunctional nicotinic receptors (nAchRs) influencing acetylcholine (Ach) release.In the presence of prazosin (0.1 μM), a selective α1-adrenoceptor antagonist, and α,β-methylene ATP (1 μM), a purinergic agonist that desensitise P2X receptors, neostigmine increased the hump component of contraction and yohimbine (0.3 μM), an α2-adrenoceptor antagonist, enhanced both components of the electrically evoked stimulation. The contraction was blocked by cyclopentolate (1 μM).In the absence of bretylium, neostigmine alone increased the hump component of contraction in a frequency-dependent manner. This increase was reversed by atropine (1 μM) and cyclopentolate (1 μM) to control levels. However, in control experiments, atropine or cyclopentolate did not detectably influence the delayed neurogenic contraction.Ach (10 μM) induced a contraction in the mouse vas deferens, either when applied alone or in the presence of neostigmine.Thus, it has been demonstrated unequivocally that the mouse vas deferens is innervated by functional cholinergic nerves, whose action is terminated by cholinesterase. Furthermore, Ach release can be enhanced by activation of prejunctional nAchRs presumably located on the cholinergic nerve terminals.British Journal of Pharmacology (2005) 146, 927–934. doi:10.1038/sj.bjp.0706357; published online 19 September 2005 [ABSTRACT FROM AUTHOR]

Abstract: The paper presents results of investigation of exchange of the clinoptilolite tuff cations with hydrogen ions from HCl solution of concentration 0.1 mmol cm-3 and ammonium ions solutions of concentrations 0.0071 to 2.6 mmol cm-3. Molal concentrations, x (mmol g-1) of cations exchanged in acid solution and in ammonium ions solutions were compared with molal concentrations of cations obtained by determination of the cation-exchange capacity of clinoptilolite tuff. The obtained results show that at ammonium ion concentrations lower than 0.1 mmol cm-3, with regard to exchange capacity for particular ions, best exchanged are Na+ ions, followed by Mg2+ and Ca2+ ions, while exchange of K+ ions is the poorest (Na+>Mg2+>Ca2+>K+). At ammonium concentrations from 0.2 to 1 mmol cm-3 the order is Na+>Ca2+>Mg2+>K+. At concentrations higher than 1 mmol cm-3 the order is Na+>Ca2+>K+>Mg2+. The results are a consequence of the uptake of hydrogen ions by zeolite samples in ammonium ions solutions at concentrations lower than 1 mmol cm-3 and indicate the importance of Mg2+ (besides Na+ ions) for the exchange between clinoptilolite cations and H+ ions, in contrast to K+ ions, whose participation in the reaction with H+ ions is the lowest. During decationization of the clinoptilolite in acid solution, best exchanged are Na+, Mg2+, and Ca2+ ions, while exchange of K+ ions is the poorest. Due to poor exchange of K+ and H+ ions and good exchange of Na+, Mg2+, and Ca2+ ions, it is to be assumed that preservation of stability of the clinoptilolite structure is caused by K+ ions present in the channel C. Clinoptilolite is dissolved in the clinoptilolite A and B channels where Na+, Mg2+, and Ca2+ ions are present. On the acid-modified clinoptilolite samples, exchange of ammonium ions is poorer than on natural zeolite. The longer the contact time of the zeolite and acid solution, the worse ammonium ions exchange. It can be assumed that H+ ions exchanged with zeolite cations are consumed for solution of aluminum in the clinoptilolite structure; therefore the concentration of H+ ions as exchangeable cations decreases. In the ammonium ion solution at a concentration of 0.0065 mmol cm-3, from the acid-modified zeolite samples, Al3+ ions are exchanged best, followed by Na+, Mg2+, Ca2+, and K+ ions. Further to the results, it is to be assumed that exchangeable Al3+ ions available from clinoptilolite dissolution are best exchanged with H+ ions in acid solution. [Copyright &y& Elsevier]

An estimation method proposed in a previous paper [St. Perisanu, Rev. Roum. Chim. 46 (2001) 1273–1280], for the activity coefficients of organic electrolytes uses the UNIFAC equation, based on group contributions. The activity coefficient of the solute is expressed as a sum of three terms: (a) electrolytic, considered as equal to the activity coefficient of a solution of same concentration of a salt of the same class not containing any organic radical; (b) non-electrolytic, corresponding to the interactions between organic radicals and solvent molecules and calculated with the UNIFAC theory; and (c) associative, due to association processes of organic ions. The latter term was calculated from experimental values of activity coefficients of organic electrolytes and the first two contributions to their values. It was observed that the associative term is a universal function of a reduced concentration, within a certain class of organic electrolytes. The reference concentration used in order to obtain the reduced values depends on the number of carbon atoms of the molecule. Its value changes only slightly, when the counter ion is changed. The correlation, generated for aqueous solutions was tested also for solutions in organic solvents. [Copyright &y& Elsevier]

This paper investigates the catalytic properties of the iridium catalysts supported on modified silicalite-1. Post-synthesis modification of silicalite-1, with solutions of ammonium compounds (NH4F and NH4OH), appeared to be an efficient method to generate the acidic sites in starting support. The modification of support led not only to changes in its acidity but also its porosity—formation of additional micro- and mesopores. The novel materials were used as supports for iridium. The iridium catalysts (1 wt.% Ir) were characterized by N2 adsorption/desorption measurements, temperature-programmed reduction with hydrogen (TPR-H2), H2 chemisorption, transmission electron microscopy (TEM), temperature-programmed desorption of ammonia (TPD-NH3), X-ray photoelectron spectroscopy (XPS) and tested in the hydrogenation of toluene reaction. The catalytic activity of iridium supported on silicalite-1 treated with NH4OH (higher porosity of support, better dispersion of active phase) was much higher than that of Ir supported on unmodified and modified with NH4F silicalite-1. [ABSTRACT FROM AUTHOR]

Due to the special properties of the ammonium salts, ammonium acetate and ammonium citrate were used to explore the best leaching conditions of rare earth with compound ammonium carboxylate. This paper explored the influence of the molar ratio, ammonium concentration, experimental temperature, and pH of the compound leaching agents on the leaching efficiency of rare earth and aluminum, and it analyzed the leaching process based on the leaching kinetics, which provides a new method for leaching rare earth from the weathered crust elution-deposited rare earth ore. The results showed that under the conditions where the molar ratio of ammonium acetate and ammonium citrate was 7:3 and the ammonium concentration was 0.15 mol/L, the leaching efficiency of rare earth was the highest when the pH of leaching agent was 4.0 and the experimental temperature was 313 K. Meanwhile, when CH3COONH4 and (NH4)3Cit were used to leach rare earth ore, the leaching reaction kinetics equation of rare earth and aluminum were obtained. In the temperature range of 283–323 K, the apparent activation energy of rare earth was 14.89 kJ/mol and that of aluminum was 19.17 kJ/mol. The reaction order of rare earth was 0.98 and that of aluminum was 0.79. The results were in accordance with the shrinking core model and indicate that the concentration of the leaching agent had a greater influence on rare earth than aluminum. This process can reduce the use of ammonium salt, and it is of great significance to extract rare earth elements from weathered crust elution-deposited rare earth ore and improve the utilization rate of resources. [ABSTRACT FROM AUTHOR]

Abstract: Rendering the cellulose fiber cationic via in situ graft copolymerization has been regarded as one of the effective approaches to improve the filler retention and distribution. In this work, cationic cellulose fibers were prepared by in situ copolymerization of vinyl acetate (VAc) and diallyldimethyl ammonium chloride (DADMAC) onto softwood sulphite pulp fibers using ceric ammonium nitrate (CAN) as a free radical initiator, followed by alkaline hydrolysis. Effects of various process parameters were systematically investigated, such as temperature, reaction time, initiator concentration, etc. Fourier transform infrared spectroscopy (FT-IR) was performed to confirm the existence of the grafted copolymers on the surface of sulphite pulps. The charge density of modified fibers was determined via back titration using a Particle Charge Detector MÜtek PCD 03. The difference between grafted fibers and virgin fibers was also revealed by the SEM observation. The resulting cationic pulps led to significant improvement of filler retention and distribution. Further improvement in filler retention was achieved by the synergy between cationic pulps and a conventional cationic polymer. In addition, the improved distribution of filler along fiber surfaces achieved by the addition of cationic pulp was demonstrated by both optical microscope and SEM observation. [Copyright &y& Elsevier]