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[Display omitted] • The amine oxide membrane pore size was found to be reversibly tunable. • The "trade-off" effect of the membrane was interestingly eliminated by the introduction of side amine oxide. • These membranes showed good anti-fouling properties and stability after multi-acid/alkali cycle treatment. Creating advanced polymer membranes with adjustable pores for various separation methods has been challenging because of the lack of new materials with adaptable and reversible chemical structures. In this study, we designed membranes using polyarylene ether sulfone/amide tertiary amine (PAES/ATA) copolymerized with polyarylene ether sulfone and polyamide tertiary amine. These membranes incorporated amine oxide units into their molecular chains by oxidizing the TA unit in the PAES/ATA copolymer chain. Applying the oxidation process improved antifouling properties, with the oxidized membrane showing a permeance recovery rate (Frr) of 95.48 % and a total fouling ratio (R t) of 9.35 %. These units also functioned as switches, altering their charge in different pH environments, thereby allowing pore size adjustment in the membranes. Notably, with the formation of amine oxide, these membranes exhibited properties distinct from the traditional "trade-off" effect, which is a persistent challenge in membrane technology development. The permeance and rejection rate of these membranes demonstrated the "simultaneous rise phenomenon" following a facile oxidation treatment to form amine oxide. This study presents a novel approach to develop membranes with new functional and tunable filtration capabilities, potentially applicable in various separation processes. [ABSTRACT FROM AUTHOR]

Developing functional membranes with switchable pores for the separation of contaminants with different sizes has been challenging due to the lack of novel materials with adaptable and adjustable structures. Polymers containing the tertiary amine (TA) unit can be transformed via oxidation into amine oxide (AO) structure that can modulate the membrane pore size. In this study, new monomers containing pH-responsive TA units and diacyl chloride containing reducible thioether (-S-) groups were used to yield pore-size-adjustable membrane resin polyarylene sulfide sulfone amide/amide tertiary amine (PASSA/ATA) at room temperature. By varying the polymerization ratio of the reaction solution, membranes could be prepared directly through non-solvent induce phase separation (NIPS) method without extra treatment. By oxidizing the TA units to AO through acid condition (H 2 O 2 /H 2 SO 4 /CH 3 COOH), the PASSA/ATA membrane can be switched from ultrafiltration to loose-nanofiltration with the rejection of RO16 and rhodamine B increased from 18.4% to 34.3 % (pristine membrane) to 91.7 % and 98.5 %. The permeance and rejection rate of the oxidized membrane were found to recover to the initial state after alkali-treatment. The mechanism of the switchable pore size was elucidated by dissipative particle dynamics (DPD) simulations. Interestingly, the oxidized PASSA/ATA membrane showed good organic solvent resistance and in nanofiltration performance, as it was capable of retaining about 95 % of Congo red in N,N-dimethylformamide (DMF) with permeance of about 10 L m−2 h−1 bar−1. This work presents a facile and low-carbon approach to develop novel membranes with multiple filtration capabilities, potentially applicable in various separation processes. Switchable polyaryl sulfide sulfone amide membrane containing tertiary amine unit: oxidation and reversible acid-base treatment. [Display omitted] • PASSA/ATA membranes were fabricated with a facile and low-carbon route. • The membrane pore size could be reversibly adjusted from ultrafiltration to nano-filtration with different pH value. • The membranes were found to have good organic solvent resistance and nanofiltration performance after facile one-step oxidation. [ABSTRACT FROM AUTHOR]

• MS detection improves dynamic range and sensitivity compared to ELSD and CAD. • Raw material impurities can transfer to drug substances in lipid nanoparticle therapies. • Hydrazone derivatization increases assay sensitivity for detection of aldehydes. • Aldehyde impurities above regulatory thresholds pose a risk to mRNA payloads. Lipid nanoparticles (LNPs) are designed to protect and transport sensitive payloads or active pharmaceutical ingredients as part of new therapeutic modalities. As a multi-component particle, a high degree of quality control is necessary to ensure raw materials are free of critical impurities that could adversely impact the drug product. In this study, we demonstrate a reversed phase liquid chromatography method hyphenated with a single quadrupole mass spectrometer (RPLC-MS) as an alternative platform to methods that incorporate evaporative light scattering or charged aerosol detectors in the detection and quantitation of critical impurities associated with LNPs. The proposed RPLC-MS method offers an increase of up to 2 orders of magnitude in dynamic range and 3 orders of magnitude in sensitivity in the analysis of impurities associated with LNPs compared to conventional detectors. Access to complementary mass data enabled the detection and identification of stability indicating impurities as part of stress studies carried out on an ionizable lipid. In addition to confirmation of peak identity, complementary mass data was also used to assess residual aldehydes in raw material and formulated LNPs in accordance with regulatory guidance. Following derivatization using 2,4-dinitrophenylhydrazine, aldehyde content in the ionizable lipid raw material was determined to exceed the reporting threshold of 0.05% in 30% of the test cases. The experimental findings observed in this study demonstrate the utility of the proposed RPLC-MS method in the identification and monitoring of stability-indicating attributes associated with LNPs as part of current Good Manufacturing Practices for improved consumer safety in drug products. [ABSTRACT FROM AUTHOR]

The 6:2 fluorotelomer sulfonamide (6:2 FTSAm)-based compounds signify a prominent group of per- and polyfluoroalkyl substances (PFAS) widely used in contemporary aqueous film-forming foam (AFFF) formulations. Despite their widespread presence, the biotransformation behavior of these compounds in wastewater treatment plants remains uncertain. This study investigated the biotransformation of 6:2 FTSAm-based amine oxide (6:2 FTNO), alkylbetaine (6:2 FTAB), and 6:2 fluorotelomer sulfonic acid (6:2 FTSA) in aerobic sludge over a 100-day incubation period. The biotransformation of 6:2 fluorotelomer sulfonamide alkylamine (6:2 FTAA), a primary intermediate product of 6:2 FTNO, was indirectly assessed. Their stability was ranked based on the estimated half-lives ( t 1/2 ): 6:2 FTAB (no obvious products were detected) ≫ 6:2 FTSA ( t 1/2 ≈28.8 days) > 6:2 FTAA ( t 1/2 ≈11.5 days) > 6:2 FTNO ( t 1/2 ≈1.2 days). Seven transformation products of 6:2 FTSA and 15 products of 6:2 FTNO were identified through nontarget and suspect screening using high-resolution mass spectrometry. The transformation pathways of 6:2 FTNO and 6:2 FTSA in aerobic sludge were proposed. Interestingly, 6:2 FTSAm was hardly hydrolyzed to 6:2 FTSA and further biotransformed to perfluoroalkyl carboxylic acids (PFCAs). Furthermore, the novel pathways for the generation of perfluoroheptanoic acid (PFHpA) from 6:2 FTSA were revealed.

A surfactant, R‐6‐AO, derived from dehydroabietic acid has been synthesized. It behaves as a highly efficient low‐molecular‐weight hydrogelator with an extremely low critical gelation concentration (CGC) of 0.18 wt % (4 mm). R‐6‐AO not only stabilizes oil‐in‐water (O/W) emulsions at concentrations above its critical micelle concentration (cmc) of 0.6 mm, but also forms gel emulsions at concentrations beyond the CGC with the oil volume fraction freely adjustable between 2 % and 95 %. Cryo‐TEM images reveal that R‐6‐AO molecules self‐assemble into left‐handed helical fibers with cross‐sectional diameters of about 10 nm in pure water, which can be turned to very stable hydrogels at concentrations above the CGC. The gel emulsions stabilized by R‐6‐AO can be prepared with different oils (n‐dodecane, n‐decane, n‐octane, soybean oil, olive oil, tricaprylin) owing to the tricyclic diterpene hydrophobic structure in their molecules that enables them to adopt a unique arrangement in the fibers. [ABSTRACT FROM AUTHOR]

Wood is an environmentally friendly material for the construction of buildings, and it possesses great physical and mechanical properties. However, under certain circumstances, it needs to be protected from degradation. This can be achieved either by proper design or treatment. In this study, eastern white pine (Pinus strobus L.) and white spruce (Picea glauca (Moench) Voss) were impregnated with propiconazole and 3-iodo-2-propynyl butylcarbamate, which are two organic fungicides. Unlike most impregnation techniques, no pressure treatment was needed. Instead, an aqueous buffered amine oxide system was used to allow the fungicides to diffuse rapidly into the wood. Many combinations of fungicides and amine oxides, as well as different diffusion times were tested to study the effect of the treatment on the dimensional stability and resistance to decay fungi. It was found that only the amine oxide affected the dimensional stability of the treated wood, with anti-swelling and anti-shrinking efficiencies values up to 30%. Amine oxides and fungicides both had an impact on the weight loss caused by the brown rot fungi. The weight loss after 10 weeks of exposure to Rhodonia placenta was reduced by half when using amine oxides or fungicides, and it was completely inhibited when they were combined. [ABSTRACT FROM AUTHOR]

Developing a new generation of polymer membranes with switchable pores for multiple separation processes remains challenging due to the lack of materials with reversible and adjustable chemical structures. Herein, amine oxide units were introduced in the chains of poly (arylene ether sulfone) via oxidizing the tertiary amine (TA) in poly (arylene ether sulfone)/amide tertiary amine (PAES/ATA) copolymer, and then served as switches to tune the pores of the prepared membranes. The smart membranes could be reversibly tuned between loose nanofiltration mode with water permeance of 178 L m−2 h−1 bar−1 and dye (e.g., Rhodamine B) rejection of 95%, and ultrafiltration mode, with water permeance of 650 L m−2 h−1 bar−1 and dye rejection of 55%, by cyclic acid-alkali treatment. The mechanism of the switchable pore size was elucidated by dissipative particle dynamics (DPD) simulations, and the results were in good agreement with experimental results. This study provides a novel and facile route to fabricate functional membranes with reversibly tunable and highly efficient filtration performance, which could be applicable to multiple separations. [Display omitted] • Amine oxide derived from tertiary amine had excellent pH stimulation response. • These amine oxide membrane pore size was found to be reversible and tunable. • These membranes showed good mechanical performance after multi-acid/alkali cycle treatment. [ABSTRACT FROM AUTHOR]

Amine oxide (AO) surfactants are used widely in North American household detergents resulting in > 44,000 mtons disposed down the drain annually. Due to AOs substantial down the drain disposal volume, wide dispersive use, and high aquatic toxicity, there is a need to evaluate ecological exposure and corresponding risk. This study refined the current knowledge regarding the fate of AO disposed down the drain through laboratory simulation studies to evaluate biodegradation in the sewer and during activated sludge wastewater treatment. A monitoring program which measured effluent AO concentrations for the dominant carbon chain lengths, C12 and C14, at 44 wastewater treatment plants (WWTP) across the continental US was also conducted. The study results were then used as input into probabilistic exposure models to predict US receiving stream concentrations. In three separate OECD 314A Sewer Water Die-Away studies AO was rapidly biodegraded with > 76% mineralized by study completion and the geometric mean of the primary biodegradation rates being 0.184 h − 1 . Two OECD 303A Activated Sludge WWTP Simulation studies showed rapid and complete biodegradation of AO with ≤ 0.09% of parent AO remaining in the effluent, ≤ 0.03% of parent AO sorbed to sludge solids, and > 97% complete mineralization of AO. Monitoring at US WWPTs confirmed low levels of AO in effluents with mean C12 and C14AO concentrations of 52.8 and 20.1 ng/L respectively. Based on the monitoring data, the 90th percentile concentrations of C12 and C14AO for 7Q10 low flow stream conditions were > 2 orders of magnitude lower than the predicted no effect concentrations indicating negligible aquatic risk from AO in US receiving streams. This study verifies that AO is safe for the aquatic environment even at the currently high usage volumes due to rapid biodegradation during transit through the sewer and wastewater treatment. [ABSTRACT FROM AUTHOR]

Surfactant is a kind of chemical that is widely used in the oilfield. It often serves as chemical oil displacement agents in the surfactant-polymer flooding or alkali-surfactant-polymer flooding. The commonly used surfactant is petroleum sulfonate. However, its unstable property often limits its use. In this paper, erucamidopropyl dimethyl amine oxide was prepared and its potential use in surfactant-polymer flooding was investigated. The results showed that the interfacial tension between crude oil and surfactant-polymer solution could be lowered to ultralow at a concentration of 0.05% (m/m) surfactant. The surfactant-polymer system (0.05% of surfactant and 1500 mg/L of polymer) could withstand adsorption twice. The core flood test indicated the above system could give 22.5% of incremental oil recovery over water flood. [ABSTRACT FROM AUTHOR]

In this study, a new category of copolymer was designed by side grafting of tertiary amines (TA) on polyaryl ether sulfone. The synthesized copolymers PES/ATA displayed superior thermal properties with a glass transition temperature of 200–225 °C. These copolymers with favorable film-forming properties were used to fabricate ultrafiltration membranes via a phase inversion approach. Surprisingly, it was found that the filtration performance of these resultant membranes could be reversibly tuned between a facile acid oxidation (CH 3 COOH:H 2 SO 4 :H 2 O 2 = 40:1:1) and alkali solution (solution of 20 wt% NaOH, immersed for 4–8 h) treatment. While the water flux of dye solution had a twofold reduction, the oxidized membranes showed distinctly enhancement of methylene blue rejection from 35% to 91.5% after oxidation treatment. Subsequently, alkali treatment of the oxidized membranes allowed their water flux to recover up to 89% as that of pristine membranes, and the methylene blue rejection can recover to almost the same as that of pristine membranes. This phenomenon was closely related to the introduced reactive TA units: the TA group in the polymeric membrane was converted into stimulus-responsive amine oxide (AO) unit, then its charge can be reversibly changed between the acid oxidation and alkali treatment, and that can be used to tune the electrostatic repulsion and further tuned the membrane pore size. In addition, compared with the polyarylene sulfone membrane, the mechanical properties of these membrane had almost no deterioration after several treatment cycle. This study supplies a novel and facile routine to fabricate functional membranes with reversible-tunable filtration properties. [Display omitted] • Tertiary amines can be facile oxidized to amine oxide which have typical excellent pH stimulation response. • These amine oxide membrane pore size was found to be reversible and tunable. • These membranes showed good mechanical performance after multi-acid-alkali cycle treatment. [ABSTRACT FROM AUTHOR]

A new kind of amine oxide surfactant – cocotriethoxylpropanediamine oxide (CTPDAO) – was synthesized by a two-step process. The molecular structure was characterized by FTIR spectra and1H NMR. The new surfactant showed high surface activity in aqueous solution in the surface tension measurement. Emulsifying capacity and wetting ability were studied in comparison to dodecyldimethylamine oxide (DDMAO). The results indicate that this new surfactant could reach the lowest surface tension of 30.4 mN m−1in aqueous solution with a critical micelle concentration (CMC) of 0.23 mmol L−1. The wetting ability of DDMAO is better than that of CTPDAO. Compared with CTPDAO, DDMAO shows a greater capacity to emulsify soybean oil, although CTPDAO is a better emulsifying agent for liquid paraffin. The foaming properties and thickening function of DDMAO and CTPDAO mixed with alcohol ether sulfate (AES) and dodecylbenzene sulfonate (LAS) were also investigated. The results show that CTPDAO is a superior foam stabilizer than DDMAO while CTPDAO and DDMAO both have excellent thickening functions. [ABSTRACT FROM PUBLISHER]

Amine oxide (AO) is a cationically charged surfactant at environmental pH and has previously been assessed in the OECD (Organization for Economic Cooperation and Development) High Production Volume (HPV) chemicals program. Typical of cationic chemicals, AO is highly aquatically toxic. In this study we vastly improve the knowledge of AO toxicity by developing acute Quantitative Structure Activity Relationships (QSARs) for an alga ( Desmodesmus subspicatus ), an invertebrate ( Daphnia magna ) and a fish ( Danio rerio ) using the appropriate array of OECD Test Guidelines. A chronic toxicity QSAR was also determined for the most sensitive taxon, Desmodesmus . Pure AO spanning the chain lengths of C8 to C16 were tested individually with trace analytical confirmation of exposures in all tests. The QSARs were all of high quality (R 2 0.92–0.98) with slopes ranging from −0.338 to −0.484. QSARs were then used to normalize toxicity outcomes for a larger, previously published data set used in HPV, European REACH (Registration, Evaluation, and Authorization of Chemicals), and peer reviewed publications. Two additional species, Lemna gibba (macrophyte) and Ankistrodesmus falcatus (alga) were studied in exposures to dodecyl (C12) AO to provide sufficient taxonomic diversity to conduct a Species Sensitivity Distribution (SSD) analysis. The SSD 5th percentile hazardous concentration (HC5) to C12 AO was found to be 0.052 mg/L which is similar to an existing AO 28-d, 3-community periphyton community bioassay normalized to C12 AO (No-observed-effect-concentration or NOEC=0.152 mg/L). The statistical properties of the SSD was probed suggesting that new studies of additional taxa would be required that were at least 10-fold more sensitive than the most sensitive taxon to move the HC5 lower by a factor of 3. The overall AO hazard assessment suggests a large margin of safety relative to published environmental exposure data. [ABSTRACT FROM AUTHOR]

The mixture proportions of three surfactants, i.e. an alkylpolyglucoside (APG), an ethoxylated fatty alcohol, and an amine oxide (AO), were optimized by applying Response Surface Methodology in order to achieve the surfactant ratio that produces the highest wetting power. The synergistic effect of the binary samples of AO with the other surfactants was firstly verified. An improvement in this synergistic effect on wettability was found in the ternary mixture. In the experimental range analyzed, the surfactant concentration ratio that produced the highest wettability was a composition with 19.3 % APG, 30.1 % ethoxylated alcohol, and 50.6 % lauramine oxide. [ABSTRACT FROM AUTHOR]

Nonionic-zwitterionic hybrid surfactants, namely N, N-dimethyl- N-dodecyl polyoxyethylene (3) amine oxide, and the corresponding betaine and/or sulfobetaine, have been synthesized. Their molecule structures were characterized by means of electrospray ionization mass spectrometry and H nuclear magnetic resonance. Compared to the structurally related conventional amine oxide, betaine and sulfobetaine, the critical micelle concentrations of the three hybrid surfactants are one order of magnitude smaller than those of traditional ones. The polyoxyethylene segment between the hydrophilic head group and the hydrophobic tail makes the surface activities of the hybrid surfactants superior to their structure-related counterparts. [ABSTRACT FROM AUTHOR]

The isoelectric point of dodecyldiethoxylamine oxide (DDEAO) containing hydroxyethyl groups was determined with the method of acid-base titration. The isoelectric point value of DDEAO is 7.8. The effects of pH, temperature and ionic strength on the aggregation behavior of DDEAO were investigated by surface tension measurements. The results show a good surface activity over a large pH range, especially under weakly acidic conditions. The surface activity of DDEAO increases trend increasing temperature. The thermodynamic parameters were also evaluated and the results show that the micelle formation is entropy-driven within the temperature range investigated. CMC values decrease with increases in ionic strength. The packing parameters ( P) were evaluated and ensure the formation of vesicles for DDEAO at various pH values, which is expected to have potential applications in some fields, such as in nanomaterials synthesis and the application in drug delivery. [ABSTRACT FROM AUTHOR]

[Display omitted] • Alkylamine oxides stabilized CO 2 -in-brine foams at low concentrations (0.1–1 wt%) • Foam stabilization was enhanced by intermolecular hydrogen bonding due to low pH. • Long alkyl chains (C 14) and salt promoted formation of large surfactant aggregates. • High protonation degree and bulk viscosity significantly increased the CO 2 -foam half-life. • CO 2 -foam coarsening followed a linear rate of bubble growth, faster than for N 2 -foam. Producing CO 2 -foams in saline environments can be a great challenge in many industrial applications, since fast gas diffusion and reduction of electrical double layer promote fast coarsening and coalescence of bubbles. Amine oxides are zwitterionic surfactants that have been shown to improve foam stability by intermolecular hydrogen bonding, but have not been investigated for CO 2 -foams yet. This paper reports a study on the use of commercial alkyldimethylamine oxides (C x DAO) as foaming agents in brine for CO 2 -foams, based on the interactions present at the low pH imposed by the dissolution of the CO 2 and the presence of salts. Despite the presence of salt and CO 2 increased the protonation degree of amine oxide molecules, favoring hydrogen bonding, a significant improvement in foam stability was only observed when using the long chain surfactant (C 14 DAO). This behavior was attributed to the synergy between increased attractive hydrophobic interactions of alkyl chains and reduced repulsion among ionic surfactant heads, which led to formation of large surfactant aggregates in bulk, as demonstrated by the significant increase in viscosity of the aqueous phase. There was also a decrease in foam drainage and coarsening rates for the foams using C 14 DAO in brine, compared to results in deionized water, suggesting that formation of hydrogen bonds is not enough to arrest the destabilization in CO 2- foams. Moreover, the linear rate of bubble growth obtained for these foams (∝ t) was higher than that reported for N 2 – or air-foams (∝ t 1/2), likely due to the high solubility of CO 2 in the aqueous phase, which accelerated the coarsening phenomena. The results of this work offer insight on the future design of foaming formulations for stabilizing CO 2- foams in applications that require the use of high salinity brines, such as carbon sequestration and oil recovery. [ABSTRACT FROM AUTHOR]

Abstract: Amine oxides are an alternative, non-ionic class of gas hydrate anti-agglomerant (AA) surfactants that are potentially more environmentally-friendly than cationic surfactant AAs. These classes of AAs work by interacting with hydrate crystal surfaces. Recently, we reported on the clathrate hydrate crystal growth inhibition of monoamine oxides using Structure II (SII) tetrahydrofuran (THF) hydrate (Kelland et al., 2012). It was determined that the best hydrate crystal growth inhibition was provided by amine oxides with n-butyl, n-pentyl or iso-pentyl groups, with tributylamine oxide being the best homofunctional trialkylamine oxide investigated. However, replacement of one butyl group with a larger group, forming the tail of an AA surfactant, lowered the inhibition significantly which could have consequences for the use of mono-amine oxides as AAs. We have now investigated bis-amine oxides and discovered that they can give even greater THF hydrate crystal growth inhibition than mono-amine oxides, particularly when the amine oxides have the correct size alkyl groups and are an optimum distance apart. The optimum alkyl group was found to be n-butyl and the optimum distance for bis-amine oxides is with a chain of 5–6 sp3 carbon atoms separating the nitrogen atoms. Alternatively, a heteroatom can be placed in this spacer chain, for example a third nitrogen atom, such as for alkylated derivatives of diethylenetriamine. These results mean that the use of bis-amine oxide surfactants could potentially lead to improved AA performance compared to mono-amine surfactants because of their greater adsorption onto hydrate surfaces. They may also act as improved synergists for polymeric kinetic inhibitors of natural gas hydrates. [Copyright &y& Elsevier]

Dodecyldiethoxylamine oxide (DDEAO) was synthesized by the reaction of dodecyldiethoxylamine with hydrogen peroxide in water as the solvent. Surface activity, wetting ability and emulsifying capacity were investigated and compared with that of dodecyldimethylamine oxide (DDMAO). Results indicate that the critical micelle concentration (CMC) of DDEAO is lower than that of DDMAO, while its surface tension at CMC (γ) is slightly higher. The wetting ability of DDEAO is similar to that of DDMAO. For its capacity of emulsifying liquid paraffin, DDEAO is found to be better than DDMAO, but it is the opposite for emulsifying soybean oil. The foaming properties and thickening function of DDEAO in mixtures with alcohol ether sulfate and alkylbenzene sulfonate were also studied. As expected, complex surfactant systems exhibit good foaming ability and DDEAO exhibits a good thickening function. [ABSTRACT FROM AUTHOR]

In this paper evaluation of surface active and application properties in liquid detergent formulations containing binary mixtures of anionic-nonionic, and anionic-cationic surfactants is discussed. Surfactants used include: linear alkylbenzene sulfonate (LAS), alcohol ether sulfate (AES-2EO), alcohol ethoxylate (AE-7EO), lauryl dimethyl amine oxide, and alkyl hydroxyethyl dimethyl ammonium chloride (AHDAC). Surface active parameters relating to the effectiveness and efficiency of surface tension reduction were determined from the surface tension data. Non-ideal solution theory was used to determine the degree of interactions between the two surfactants, and the conditions under which a mixture of two surfactants show synergism in surface active properties. Our data indicated that synergism in mixed surfactants increases with the degree of charge difference between the surfactants. In both mixed micelle and mixed monolayer formation, the degree of interactions between the two surfactants in the mixture increased in the following order: LAS/AE < AES-2EO/amine oxide < AES-2EO/AHDAC. This synergistic behavior as presented in this paper leads to unique application properties and improved performance in terms of foam volume, and soil removal which has applications in formulation of dishwashing liquids, and laundry detergents. [ABSTRACT FROM AUTHOR]

Abstract: Formation and properties of viscoelastic wormlike aqueous micellar solutions of the zwitterionic surfactant p-dodecyloxybenzyldimethylamine oxide (pDoAO) were studied. Semi-dilute aqueous solutions of pDoAO show a sharp increase in viscosity, which exceeds 160 cST for concentrations >50mM, leading to viscoelastic solutions. Viscoelasticity relates to the surfactant charge type. In fact this viscoelastic system reverses to fluid when acid is added (pH<2), which changes the system to cationic. Under acidic conditions the system resembles solutions of the similar cationic surfactant p-dodecyloxybenzyltrimethylammonium bromide, (pDoTABr) in terms of viscosity. Properties of aqueous solutions of pDoAO were investigated by dynamic light scattering (DLS), rheology and small angle neutron scattering (SANS). Data support the idea that small micelles grow in length (wormlike or threadlike micelles) as surfactant concentration increases and viscoelastic solutions form as micelles become entangled. The micellar diameter as calculated by different techniques is about 5nm. [Copyright &y& Elsevier]

Abstract: An aqueous reaction medium, based on a surfactant solution of diethyltetradecylamine N-oxide (AOE-14), was developed for the enantioselective epoxidation of 1,2-dihydronaphthalene and of various cis-β-alkyl styrenes with increasing hydrophobicity, using bleach as oxidant and the Jacobsen chiral (salen)Mn(III) as catalyst. AOE-14 is able to both solubilize all reactants in water and bind the metal of the salen complex acting as coligand. Its use leads to good yields (>75%) and to ee values ranging from 75% up to 91% even in the case of cis-β-alkyl styrenes where lower cis/trans epoxide ratios are observed. The ratio of surfactant/substrate used is 1:1 or 4:1, much lower than those generally used in the literature. [Copyright &y& Elsevier]

The paper is an overview of the results of the investigation on electrochemical promotion of three catalytic reactions: methane oxidation with oxygen, NO reduction with hydrogen at 135 °C and Fischer–Tropsch synthesis (FTS) at 170 °C in the [CH4/O2(or NO/H2 or CO/H2)/Ar//Pt (or Pt/Ru)//PBI(H3PO4)/H2, Ar] fuel cell. It has been shown that the partial methane oxidation to C2H2 and the C2 selectivity were electrochemically promoted by the negative catalyst polarization. This was also the case in NO reduction with hydrogen for low NO and H2 partial pressures. In both cases the catalytic reactions have been promoted by the electrochemically produced hydrogen. It has been found that the NO reduction with hydrogen on the Pt/PBI strongly depends on NO and hydrogen partial pressures in the working gas mixture. At higher NO and H2 partial pressures the catalysis is promoted by the electrochemical pumping of H+ from the catalyst, i.e. at positive polarization. FTS demonstrated the highest methane production rate (11% of CO conversion) at zero fuel cell voltage. [ABSTRACT FROM AUTHOR]

Focusing on size-selected gold clusters consisting of up to 20 atoms, that is, in the size regime where properties cannot be obtained from those of the bulk material through scaling considerations, we discuss the current state of understanding pertaining to various factors that control the reactivity and catalytic activity of such nanostructures, using the CO oxidation reaction catalyzed by the gold nanoclusters adsorbed on MgO as a paradigm. These factors include the role of the metal-oxide support and its defects, the charge state of the cluster, structural fluxionality of the clusters, electronic size effects, the effect of an underlying metal support on the dimensionality, charging and chemical reactivity of gold nanoclusters adsorbed on the metal-supported metal-oxide, and the promotional effect of water. We show that through joined experimental and first-principles quantum mechanical calculations and simulations, a detailed picture of the reaction mechanism emerges. [ABSTRACT FROM AUTHOR]

A number of anions and cations have been incorporated into TiO2 as support for gold catalysts and also into as-prepared Au/TiO2 catalysts at levels of 0.4 mol% and 2.5 mol% with respect to the support. The activities of the catalysts for CO oxidation reveal that the at the higher concentration level of the ions, in all cases, a decrease in activity compared with unmodified Au/TiO2. However, and more interestingly, addition of only 0.4 mol% of the ions to the support, prior to gold addition, in most cases resulted in activity enhancement whilst similar addition to Au/TiO2 resulted in decrease in activity. Attempts have been made to understand the origin of these effects. [ABSTRACT FROM AUTHOR]

The use of biocide in oral care products is important for controlling microbial pathogens. However, the use of biofilm tests that investigate repeated exposure to biocide, to mimic in situ treatment, has rarely been reported in the literature. The present study describes the application of a biofilm-based efficacy protocol, for testing the effect of repeated exposure to antimicrobials on biofilm, in an attempt to mimic oral care regimens. The activity of different treatment regimens, including repeated exposure to amine oxide (AO; C10-C16-alkyldimethyl N-oxides; 1.1% v/v), was conducted against 16-h Streptococcus mutans biofilms grown on hydroxyapatite disks. Single exposure to AO alone produced a 3 log10 reduction in microbial count, but when combined with mechanical removal, a 5 log10 reduction in microbial count was observed. Treatments incorporating repeated exposure to AO reduced the microbial count below the level of detection, even when exposure to AO was interspersed with recovery periods. The presence of organic load produced an additional 2 log10 reduction in the microbial count. This study showed that the application of a biofilm-based efficacy protocol to mimic oral care regimens allowed the reproducible testing of repeated antimicrobial exposures against bacterial biofilm. In addition, AO was confirmed to be an excellent biocide for eliminating S. mutans biofilms and could therefore be beneficial in oral care formulations. [ABSTRACT FROM AUTHOR]

Pyridine and dimethylamine have been studied at clean and oxidised Cu(110) surfaces as model systems for the interaction of amines with heterogeneous catalysts using scanning tunnelling microscopy and X-ray photoelectron spectroscopy. Both molecules interact strongly with sub monolayer concentrations of chemisorbed oxygen causing a change from the well known p(2×1)O(a) islands to a (3×1) structure. XPS shows a 1:1 correspondence between the concentration of surface oxygen and that of chemisorbed pyridine but the stoichiometry of the dimethylamine/oxygen system could not be directly measured because of a slow reaction which results in the desorption of oxygen as water and the formation of a chemisorbed amide. The amide also decomposes at room temperature and desorbs leaving a clean surface. However, the 2:1 stoichiometry of the dimethylamine/oxygen reaction suggests a 1:1 dimethylamine:oxygen ratio in the (3×1) structure. The results of the study are interpreted in terms of an amine–oxygen complex, which may provide a general model for the interaction of amines with oxygen at metal surfaces. [ABSTRACT FROM AUTHOR]

Abstract: C31G, which has potent activity against the human immunodeficiency virus type 1 (HIV-1) and an established record of safety in animal studies and human trials, is a microbicidal agent comprised of a buffered equimolar mixture of two amphoteric, surface-active agents: an alkyl amine oxide (C14AO) and an alkyl betaine (C16B). Studies of long-term in vitro exposure to C31G and its constituents have suggested that the components of C31G may contribute differentially to its toxicity and efficacy. In the present studies, in vitro assays of cytotoxicity and anti-HIV-1 activity demonstrated that C16B was slightly less cytotoxic compared to either C31G or C14AO, whereas the anti-HIV-1 activities of C31G and its individual constituents were similar. In the murine model of cervicovaginal microbicide toxicity, in vivo exposure to C14AO resulted in severe cervical inflammation followed by a delayed disruption of the columnar epithelium. In contrast, exposure to C16B caused severe cervical epithelial disruption and a secondary, less intense inflammatory response. These results demonstrate that (i) there are both mechanistic and temporal differences in toxicity associated with the components of C31G not necessarily predicted by in vitro assessments of cytotoxicity and (ii) contributions of each component to the anti-HIV-1 activity of C31G appear to be equal. In addition, these findings indicate that direct and indirect mechanisms of in vivo toxicity can be observed as separate but interrelated events. These results provide further insight into the activity of C31G, as well as mechanisms potentially associated with microbicide toxicity. [Copyright &y& Elsevier]

Abstract: We present a temperature-induced sedimentation/dispersion transition of ionic vesicles in the system of alkyldimethylamine oxide hemihydrochloride (CnDMAOHCl) with a hydrocarbon chain length of 12–16 (, 14, and 16) and sodium 2-naphthalenesulfonate (NaNphS). The temperature-sensitive sedimentation/dispersion of ionic vesicles took place around a temperature of 50 °C, which was weakly dependent on the alkyl chain length. The combined effect of the thermally induced dissociation of the counterions from the vesicle and a hydrogen bonding between the nonionic and the cationic head groups is likely to be responsible for this unique behavior. [Copyright &y& Elsevier]

This investigation examined the effects of common aqueous biocides and disinfectant foams derived from them on Pseudomonas aeruginosa biofilms. Biofilms were grown on stainless steel coupons under standardised conditions in a reactor supplemented with low concentrations of organic matter to simulate conditions prevalent in industrial systems. Five-day-old biofilms formed under ambient conditions with continuous agitation demonstrated a low coefficient of variation (5.809%) amongst viable biofilm bacteria from independent trials. Scanning electron microscopy revealed biofilms on coupons with viable biofilm bacteria observed by confocal microscopy. An aqueous solution of a common foaming agent amine oxide (AO) produced negligible effects on bacterial viability in biofilms ( p > 0.05). However, significant biofilm inactivation was noted with aqueous solutions of common biocides (peracetic acid, sodium hypochlorite, sodium ethylenediaminetetraacetic acid) with or without AO ( p < 0.05). Aereation of a mixture of AO with each of these common biocides resulted in significant reductions in the viability of biofilm bacteria ( p < 0.05). In contrast, limited effects were noted by foam devoid of biocides. A relationship between microbial inactivation and the concentration of biocide in foam (ranging from 0.1 – 0.5%) and exposure period were noted ( p < 0.05). Although, lower numbers of viable biofilm bacteria were recovered after treatment with the disinfectant foam than by the cognate aqueous biocide, significant differences between these treatments were not evident ( p > 0.05). In summary, the studies revealed significant biofilm inactivation by biocidal foam prepared with common biocides. Validation of foam disinfectants in controlled trials at manufacturing sites may facilitate developments for clean in place applications. Advantages of foam disinfectants include reductions in the volumes of biocides for industrial disinfection and in their disposal after use. [ABSTRACT FROM AUTHOR]

• Fluoroether amine oxide surfactants with excellent surface properties. • PFOA may be replaced by fluoroether surfactants. • Oxygen atoms within fluoroether chains are hydrophobic. Persistent organic pollutants (POPs) includes long-chained fluorosurfactants, for instance, perfluorooctanonate (PFOA) and perfluorooctanesulfonate (PFOS). In order to find out alternative fluorosurfactants, we synthesized eight amine oxides with a fluoroether chain. Their surface properties were evaluated and compared with perfluoroalkyl and hydrocarbon analogues. The surface tensions at critical micelle concentration (γ cmc) for the eight amine oxides with a fluoroether chain were at a range from 15.5 to 23.0 mN/m, and γ cmc of four fluoroether amine oxides were below 17 mN/m comparable to perfluorooctyl analogues (16.4 mN/m) and much lower than perfluorohexyl (20.5 mN/m) and hydrocarbon analogues (24.2 and 24.7 mN/m). The critical micelle concentration (cmc) for the eight amine oxides with a fluoroether chain were 3 to 535 × 10−4 mol/L. The cmc of four fluoroether amine oxides were 3 to 21 × 10−4 mol/L (0.2 to 1.0 g/L) comparable to perfluorooctyl (0.4 g/L) and hydrocarbon analogues (4 and 10 × 10−4 mol/L) and much lower than perfluorohexyl analogue (36.9 g/L). The surface excesses, the limiting molecule areas and the free energies of micellization of amine oxides were calculated. Fluoroether surfactants are promising alternatives for PFOA and PFOS. [Display omitted] [ABSTRACT FROM AUTHOR]

The interaction of solid alkyldimethylamine oxide and ditallowdimethylammonium chloride (DTMAC) and ditallow dimethylammonium sulfate (DTMAS) quats in representative types of fabric softener systems was studied with particular focus on synergistic behavior. Softening, whiteness retention, wetting, static build-up and detersiveness were evaluated for laundry rinses, laundry detergents and dryer sheets. In laundry rinses, blends of amine oxide and DTMAC proved to be synergistic for improving the wetting of cotton towels. Although no synergism was observed in laundry detergents, formulations containing amine oxide gave better detersiveness than systems with DTMAC without the splotching associated with the quaternary salt. In dryer sheets, it was discovered that blends of amine oxide and DTMAS gave synergistic softening of cotton towels and were unexpectedly effective in preventing static charge build-up on polyester fabric. [ABSTRACT FROM AUTHOR]

A solvent extraction technique using 0.01 M solution of trilaurylamine N-oxide in benzene as extractant has been used to concentrate mercury efficiently from water solutions with or without the presence of 0.02 M KI in weakly acidic media. In addition to unmodified aqueous solutions, mercury can be extracted quantitatively from aqueous iodide solutions that are up to 1 M in HCl, HSO, and HNO in a single equilibration. Distribution coefficients and separation factors of several elements relative to mercury(II) are reported for media that contain 0.1 M HCl and 0.02 M KI. The reagent is superior to aliphatic amines and quaternary amines for the extraction of mercury from aqueous iodide solutions. [ABSTRACT FROM AUTHOR]

Abstract: Lithiation of 3-methoxymethyl quinuclidine N-oxide occurs regioselectively to generate the 2-lithio 3-methoxymethyl derivative which can be trapped out with non-enolisable electrophiles to give 2,3-disubstituted quinuclidine N-oxide derivatives in good yield. [Copyright &y& Elsevier]

• Amine oxides were deoxygenated to amines over a TiO 2 photocatalyst. • Solvent alcohols simultaneously acted as a hydrogen donor. • Apparent quantum efficiency reached 32.7% at λ= 361 nm at 298 K. • The reaction rate greatly increased at 337 K. • This reaction proceeded under solar light even under a static condition. Deoxygenation of amine oxides to corresponding amines is one of the important reactions in the fields of organic chemistry, biochemistry and medical chemistry. Since this reaction generally requires undesired hydrogen sources (reductants) and harsh conditions such as high temperatures and high pressure, a simpler and safe catalytic reaction system working under milder conditions is highly desired. A very simple method for deoxygenation of amine oxides to corresponding amines, i.e., photocatalytic reaction in an alcohol suspension of titanium(IV) oxide (TiO 2) without any other elements, is desired in this paper. Photocatalytic deoxygenation of amine oxides occurred at room temperature and under atmospheric pressure with an alcohol acting as a hydrogen donor. We report variations of this reaction system including variation in substrates (amine oxides) and alcohols and the effects of reaction conditions (amine oxide concentration, reaction temperature and light sources) on deoxygenation. The characteristic of this reaction system, i.e., a thermal acceleration effect, is discussed in detail on the basis of results of physicochemical analysis. Finally, we show that this reaction proceeds under solar light even under a static condition (without stirring of the suspension). [ABSTRACT FROM AUTHOR]

We measured the absolute rate constants for the hydrogen peroxide oxidation of two different octyl dimethyl amines in isopropanol/water mixtures at 23°C. The amines were 1-octyl dimethyl amine ( 1) and 2-ethylhexyl dimethyl amine ( 2); their structures were analogous to those most often encountered in commercial alkyl dimethyl amine oxide production. The observed first-order rate constants for the disappearance of amine across a range of H2O2 concentrations (0.5–8 M) indicated that the overall rate was first-order in amine and 3/2-order in H2O2. Calculations showed k 1=0.16 M−1h−1, k 2=0.046 M−1h−1, and k 1/ k 2=3.5. The rates appeared to decrease with increasing steric hindrance around the nitrogen atom. We also investigated the effect of water on the reaction rates. When [H2O]<∼4.5 M in isopropanol, the rates increased with increasing [H2O]; for [H2O]>∼4.5 M, the rates were insensitive to [H2O]. [ABSTRACT FROM AUTHOR]