Titanium dioxide photocatalytic degradation of aliphatic ethers and their primary oxidation products

Two studies were performed to obtain fundamental mechanistic information on the TiO2 catalyzed degradation of organic substrates irradiated at 350 nm in dilute aqueous solutions under oxygenated conditions: (a) The photodecomposition of methyl tert-butyl ether (MTBE) and its intermediate products from β-oxidation, 2-methoxy-2-methylpropanol and 2-methoxy-2-methylpropanol. (b) The photodecomposition of two haloethers, bis-(2-chloroethyl) ether, and bis-(2-chloroisopropyl) ether. Controls were carried out throughout the two studies in the absence of light, and without the semiconductor in order to evaluate the role of photolysis. ^ The syntheses of proposed intermediate products, 2-methoxy-2-methylpropanol, 2-methoxy-2-methylpropanal, 2-methoxy-2-methylpropanoic acid, 2-chloroethyl formate, and 1-chloro-2-propyl acetate, were performed. The formation of these products in the titanium dioxide photocatalytic oxidation of the substrates of interest was also confirmed. TiO2 photocatalysis is a very effective method for the mineralization of aliphatic ethers and their primary oxidation products. ^

Mechanistic studies on the degradation of gasoline oxygenates by advanced oxidation technologies and the reaction of 4-methyl-1,2,4-triazoline-3,5-dione with tetracyclopropylethylene

Gasoline oxygenates (MTBE, methyl tert-butyl ether; DIPE, di-isopropyl ether; ETBE, ethyl tert-butyl ether; TAME, tert-amyl ether) are added to gasoline to boost octane and enhance combustion. The combination of large scale use, high water solubility and only minor biodegradability has now resulted in a significant gasoline oxygenate contamination occurring in surface, ground, and drinking water systems. Combination of hydroxyl radical formation and the pyrolytic environment generated by ultrasonic irradiation (665 kHz) leads to the rapid degradation of MTBE and other gasoline oxygenates in aqueous media. ^ The presence of oxygen promotes the degradation processes by rapid reaction with carbon centered radicals indicating radical processes involving O 2 are significant pathways. A number of the oxidation products were identified. The formation of products (alcohols, ketones, aldehydes, esters, peroxides, etc) could be rationalized by mechanisms which involve hydrogen abstraction by OH radical and/or pyrolysis to form carboncentered radicals which react with oxygen and follow standard oxidation chain processes. ^ The reactions of N-substituted R-triazolinediones (RTAD; R = CH 3 or phenyl) have attracted considerable interest because they exhibit a number of unusual mechanistic characteristics that are analogous to the reactions of singlet oxygen (1O2) and offer an easy way to provide C-N bond(s) formation. The reactions of triazolinedione with olefins have been widely studied and aziridinium imides are generally accepted to be the reactive intermediates. ^ We observed the rapid formation of an unusual intermediate upon mixing tetracyclopropylethylene with 4-methyl-1,2,4-triazoline-3,5-dione in CDCl 3. Detailed characterization by NMR (proton, 13C, 2-D NMRs) indicates the intermediate is 5,5,6,6-tetracyclopropyl-3-methyl-5,6-dihydro-oxazolo[3,2- b][1,2,4]-triazolium-2-olate. Such products are extremely rare and have not been studied. Upon warming the intermediate is converted to 2 + 2 diazetidine (major) and ene product (minor). ^ To further explore the kinetics and dynamics of the reaction activation energies were obtained using Arrhenius plots. Activation energies for the formation of the intermediate from reactants, and 2+2 adduct from the intermediate were determined as 7.48 kcal moll and 19.8 kcal mol−1 with their pre-exponential values of 2.24 × 105 dm 3 mol−1 sec−1 and 2.75 × 108 sec−1, respectively, meaning net slow reactions because of low pre-exponential values caused by steric hindrance. ^

Development of a mathematical and computer model to assess water quality impacts of hazardous compounds from minor gasoline spills in the inter-tidal zone of the Miami River, Florida

The objective of this study was to develop a model to predict transport and fate of gasoline components of environmental concern in the Miami River by mathematically simulating the movement of dissolved benzene, toluene, xylene (BTX), and methyl-tertiary-butyl ether (MTBE) occurring from minor gasoline spills in the inter-tidal zone of the river. Computer codes were based on mathematical algorithms that acknowledge the role of advective and dispersive physical phenomena along the river and prevailing phase transformations of BTX and MTBE. Phase transformations included volatilization and settling. ^ The model used a finite-difference scheme of steady-state conditions, with a set of numerical equations that was solved by two numerical methods: Gauss-Seidel and Jacobi iterations. A numerical validation process was conducted by comparing the results from both methods with analytical and numerical reference solutions. Since similar trends were achieved after the numerical validation process, it was concluded that the computer codes algorithmically were correct. The Gauss-Seidel iteration yielded at a faster convergence rate than the Jacobi iteration. Hence, the mathematical code was selected to further develop the computer program and software. The model was then analyzed for its sensitivity. It was found that the model was very sensitive to wind speed but not to sediment settling velocity. ^ A computer software was developed with the model code embedded. The software was provided with two major user-friendly visualized forms, one to interface with the database files and the other to execute and present the graphical and tabulated results. For all predicted concentrations of BTX and MTBE, the maximum concentrations were over an order of magnitude lower than current drinking water standards. It should be pointed out, however, that smaller concentrations than the latter reported standards and values, although not harmful to humans, may be very harmful to organisms of the trophic levels of the Miami River ecosystem and associated waters. This computer model can be used for the rapid assessment and management of the effects of minor gasoline spills on inter-tidal riverine water quality. ^

Therapeutic azulenyl nitrone antioxidants

The reactions of nitrones with free radicals have been widely studied both in vitro and in vivo. In comparison to classical chain-breaking phenolic antioxidants (such as Vitamin E and butylated hydroxytoluene [BHT]), conventional phenyl-substituted nitrones have much higher oxidation potentials. Azulenyl-substituted nitrones have lower oxidation potentials than conventional nitrones and react efficiently with free radicals in vitro and in vivo. The design and synthesis of novel azulenyl nitrones with yet lower oxidation potentials, prepared from commercially available guaiazulene, has produced several 1,2-trans -bis-azulenyl ethene compounds with enhanced antioxidant activity. A convenient 1H NMR-based assay for assessing the potency of chain-breaking antioxidants has shown these novel nitrones to be more than 300 times more potent in inhibiting the free radical-mediated aerobic peroxidation of cumene than α-phenyl-N-tert-butyl nitrone (PBN) and the experimental stroke drug NXY-059. The low oxidation potential of these novel nitrones and the stability of the corresponding radical cation have been implicated in the explanation of the increased antioxidant potency of these second generation azulenyl nitrones. Based on the results of these in vitro studies, the first of these novel compounds, stilbazulenyl nitrone (STAZN), was investigated in animal models of disease known to involve free radical-mediated pathology. In view of STAZN's marked lipophilicity and anticipated blood brain barrier permeability, neurodegenerative conditions were investigated. All animal experiments were performed at the University of Miami by members of the Ginsberg research group. STAZN was neuroprotective in traumatic brain injury in rats. It also provided exceptional neuroprotection in an animal model of stroke. The concentration of STAZN required for neuroprotection was 300–600 times less than doses of PBN or NXY-059 required for similar effect. Thus, the benefits of greater antioxidant potency sought by lowering the oxidation potential of nitrones appear to have been reaped both in vitro and in vivo. In spite of the challenges and difficulties in understanding free radical-mediated pathology, this work establishes that considerations such as redox potential and lipophilicity can provide a very fruitful rationale for the design of therapeutic azulenyl nitrone antioxidants. ^

Organic geochemistry of sediments from sapropel 94 of ODP Hole 161-974C

Analysis of the molecular composition of the organic matter (OM) from whole sediment samples can avoid analytical bias that might result from isolation of components from the sediment matrix, but has its own analytical challenges. We evaluated the use of GC * GC-ToFMS to analyze the pyrolysis products of six whole sediment samples obtained from above, within and below a 1 million year old OM-rich Mediterranean sapropel layer. We found differences in pyrolysis products

Seasonal variations in surface metabolite composition of Fucus vesiculosus and Fucus serratus sampled at outer Kiel Fjord (August 2012 - July 2013)

The chemical composition of surface associated metabolites of two Fucus species (Fucus vesiculosus and Fucus serratus) was analysed by means of gas chromatography-mass spectrometry (GC-MS) to describe temporal patterns in chemical surface composition. Method: The two perennial brown macroalgae F. vesiculosus and F. serratus were sampled monthly at Bülk, outer Kiel Fjord, Germany (54°27'21 N / 10°11'57 E) over an entire year (August 2012 - July 2013). Per month and species six non-fertile Fucus individuals were collected from mixed stands at a depth of 0.5 m under mid water level. For surface extraction approx. 50 g of the upper 5-10 cm apical thalli tips were cut off per species. The surface extraction of Fucus was performed according to the protocol of de Nys and co-workers (1998) with minor modifications (see Rickert et al. 2015). GC/EI-MS measurements were performed with a Waters GCT premier (Waters, Manchester, UK) coupled to an Agilent 6890N GC equipped with a DB-5 ms 30 m column (0.25 mm internal diameter, 0.25 mM film thickness, Agilent, USA). The inlet temperature was maintained at 250°C and samples were injected in split 10 mode. He carrier gas flow was adjusted to 1 ml min-1. Alkanes were used for referencing of retention times. For further details (GC-MS sample preparation and analysis) see the related publication (Rickert et al. submitted to PLOS ONE).

Intrinsically flexible electronic materials for smart device applications

A novel method to fabricate chemically linked conducting polymer–biopolymer composites that are intrinsically flexible and conducting for functional electrode applications is presented. Polypyrrole was synthesised in situ during the cellulose regeneration process using the 1-butyl-3-methylimidazolium chloride ionic liquid as a solvent medium. The obtained polypyrrole–cellulose composite was chemically blended and showed flexible polymer properties while retaining the electronic properties of a conducting polymer. Addition of an ionic liquid such as trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, enhanced the flexibility of the composite. The functional application of these materials in the electrochemically controlled release of a model drug has been demonstrated. This strategy opens up a new design for a wide spectrum of materials for smart electronic device applications wherein the functionality of doping and de-doping of conducting polymers is retained and their processability issue is addressed by exploiting an ionic liquid route.

High Pressure Speed of Sound and Related Thermodynamic Properties of 1-Alkyl-3-methylimidazolium Bis[(trifluoromethyl)sulfonyl]imides (from 1-Propyl- to 1-Hexyl-)

The knowledge of thermodynamic high-pressure speed of sound in ionic liquids (ILs) is a crucial way either to study the nature of the molecular interactions, structure and packing effects or to determine other key thermodynamic properties of ILs essential for their applications in any chemical and industrial processes. Herein, we report the speed of sound as a function temperature at pressures up to 101 MPa in four ultrapure ILs: 1-propyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, 1-pentyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, and 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, taking into consideration their relaxation behavior. Additionally, to further improve the reliability of the speed of sound results, the density, isentropic compressibility, and isobaric heat capacity as a function of temperature and pressure are calculated using an acoustic method.

Mercury capture on a supported chlorocuprate(II) ionic liquid adsorbent studied using operando synchrotron X-ray absorption spectroscopy

Mercury scrubbing from gas streams using a supported 1-butyl-3-methylimidazolium chlorocuprate(II) ionic liquid ([C4mim]2[Cu2Cl6]) has been studied using operando EXAFS. Initial oxidative capture as [HgCl3]– anions was confirmed, this was then followed by the unanticipated generation of mercury(I) chloride through comproportionation with additional mercury from the gas stream. Combining these two mechanisms leads to net one electron oxidative extraction of mercury from the gas with increased potential capacity and efficiency for supported ionic liquid mercury scrubbers.

Synthesis and characterization of hybrids derived from vermiculite chloropropyl and aliphatic diamines

ALVES, Ana Paula de Melo et al. Synthesis and characterization of hybrids derived from vermiculite chloropropyl and aliphatic diamines. Journal of Thermal Analysis and Calorimetry, v.87, n. 3, p.771–774, 2007.

Recouvrements à base de dextrane pour applications médicales

L’ingénierie des biomatériaux a connu un essor prodigieux ces dernières décennies passant de matériaux simples à des structures plus complexes, particulièrement dans le domaine cardiovasculaire. Cette évolution découle de la nécessité des biomatériaux de permettre la synergie de différentes propriétés, dépendantes de leurs fonctions, qui ne sont pas forcément toutes compatibles. Historiquement, les premiers matériaux utilisés dans la conception de dispositifs médicaux étaient ceux présentant le meilleur compromis entre les propriétés physico-chimiques, mécaniques et biologiques que nécessitait leur application. Cependant, il se peut qu’un tel dispositif possède les bonnes propriétés physico-chimiques ou mécaniques, mais que sa biocompatibilité soit insuffisante induisant ainsi des complications cliniques. Afin d’améliorer ces propriétés biologiques tout en conservant les propriétés de volume du matériau, une solution est d’en modifier la surface. L’utilisation d’un revêtement permet alors de moduler la réponse biologique à l’interface biomatériau-hôte et de diminuer les effets indésirables. Ces revêtements sont optimisés selon deux critères principaux : la réponse biologique et la réponse mécanique. Pour la réponse biologique, les deux approches principales sont de mettre au point des revêtements proactifs qui engendrent l’adhérence, la prolifération ou la migration cellulaire, ou passifs, qui, principalement, sont inertes et empêchent l’adhérence de composés biologiques. Dans certains cas, il est intéressant de pouvoir favoriser certaines cellules et d’en limiter d’autres, par exemple pour lutter contre la resténose, principalement due à la prolifération incontrôlée de cellules musculaires lisses qui conduit à une nouvelle obstruction de l’artère, suite à la pose d’un stent. La recherche sur les revêtements de stents vise, alors, à limiter la prolifération de ces cellules tout en facilitant la ré-endothélialisation, c’est-à-dire en permettant l’adhérence et la prolifération de cellules endothéliales. Dans d’autres cas, il est intéressant d’obtenir des surfaces limitant toute adhérence cellulaire, comme pour l’utilisation de cathéter. Selon leur fonction, les cathéters doivent empêcher l’adhérence cellulaire, en particulier celle des bactéries provoquant des infections, et être hémocompatibles, principalement dans le domaine vasculaire. Il a été démontré lors d’études précédentes qu’un copolymère à base de dextrane et de poly(méthacrylate de butyle) (PBMA) répondait aux problématiques liées à la resténose et qu’il possédait, de plus, une bonne élasticité, propriété mécanique importante due à la déformation que subit le stent lors de son déploiement. L’approche de ce projet était d’utiliser ce copolymère comme revêtement de stents et d’en améliorer l’adhérence à la surface en formant des liens covalents avec la surface. Pour ce faire, cela nécessitait l’activation de la partie dextrane du copolymère afin de pouvoir le greffer à la surface aminée. Il était important de vérifier pour chaque étape l’influence des modifications effectuées sur les propriétés biologiques et mécaniques des matériaux obtenus, mais aussi d’un point de vue de la chimie, l’influence que cette modification pouvait induire sur la réaction de copolymérisation. Dans un premier temps, seul le dextrane est considéré et est modifié par oxydation et carboxyméthylation puis greffé à des surfaces fluorocarbonées aminées. L’analyse physico-chimique des polymères de dextrane modifiés et de leur greffage permet de choisir une voie de modification préférentielle qui n’empêchera pas ultérieurement la copolymérisation. La carboxyméthylation permet ainsi d’obtenir un meilleur recouvrement de la surface tout en conservant la structure polysaccharidique du dextrane. Le greffage du dextrane carboxyméthylé (CMD) est ensuite optimisé selon différents degrés de modification, tenant compte aussi de l’influence que ces modifications peuvent induire sur les propriétés biologiques. Finalement, les CMD précédemment étudiés, avec des propriétés biologiques définies, sont copolymérisés avec des monomères de méthacrylate de butyle (BMA). Les copolymères ainsi obtenus ont été ensuite caractérisés par des analyses physico-chimiques, biologiques et mécaniques. Des essais préliminaires ont montrés que les films de copolymères étaient anti-adhérents vis-à-vis des cellules, ce qui a permis de trouver de nouvelles applications au projet. Les propriétés élastiques et anti-adhérentes présentées par les films de copolymères CMD-co-PBMA, les rendent particulièrement intéressants pour des applications comme revêtements de cathéters.

Lipid oxidation kinetics of ozone-processed shrimp during iced storage using peroxide value measurements

In this research, in situ generated ozone exposure/wash cycles of 1, 3, and 5 min applied to shrimp samples either before (BIS) or during iced storage (DIS) has been used to study the lipid oxidation kinetics using the peroxide values (PV). The induction period (IP) as well as PV at end of the IP (PVIP) have been obtained. The rate constants (k) as well as half-lives (t1/2) of hydroperoxides formation for different oxidation stages were calculated. The results showed that both IP and PVIP were lower with BIS (IP between 4.35±0.09 and 5.08±0.23 days; PVIP between 2.92±0.06 and 3.40±0.18 mEq kg−1) compared with DIS (IP between 5.92±0.12 and 6.14±0.09 days; PVIP between 4.49±0.17 and 4.56±0.10 mEq kg−1). The k value for DIS seemed to be the greater compared to BIS. In addition, whilst decreases and increases in t1/2 were found at propagation, respectively, for BIS and DIS, decreases and increases were only found at the induction of oxidation stage(s) for BIS. Further, the PV of ozone-processed samples would fit first order lipid oxidation kinetics independent of duration of ozone exposures. For the first time, PV measurements and fundamental kinetic principles have been used to describe how increasing ozone exposures positively affects the different oxidation stages responsible for the formation of hydroperoxides in ozone-processed shrimp.

Synthesis and characterization of hybrids derived from vermiculite chloropropyl and aliphatic diamines

ALVES, Ana Paula de Melo et al. Synthesis and characterization of hybrids derived from vermiculite chloropropyl and aliphatic diamines. Journal of Thermal Analysis and Calorimetry, v.87, n. 3, p.771–774, 2007.

Chromatographic analysis and survey studies to evaluate the emerging drugs of synthetic cannabinoids in Scotland and Saudi Arabia

Synthetic cannabinoid receptor agonists or more commonly known as synthetic cannabinoids (SCs) were originally created to obtain the medicinal value of THC but they are an emerging social problem. SCs are mostly produced coated on herbal materials or in powder form and marketed under a variety of brand names, e.g. “Spice”, “K2”. Despite many SCs becoming controlled under drug legislation, many of them remain legal in some countries around the world. In Scotland, SCs are controlled under the Misuse of Drugs Act 1971 and Psychoactive Substances Act 2016 that only cover a few early SCs. In Saudi Arabia, even fewer are controlled. The picture of the SCs-problem in Scotland is vague due to insufficient prevalence data, particularly that using biological samples. Whilst there is evidence of increasing use of SCs throughout the world, in Saudi Arabia, there is currently no data regarding the use of products containing SCs among Saudi people. Several studies indicate that SCs may cause serious toxicity and impairment to health therefore it is important to understand the scale of use within society. A simple and sensitive method was developed for the simultaneous analysis of 10 parent SCs (JWH-018, JWH-073, JWH-250, JWH-200, AM-1248, UR-144, A-796260, AB-FUBINACA, 5F-AKB-48 and 5F-PB-22) in whole blood and 8 corresponding metabolites (JWH-018 4-OH pentyl, JWH-073 3-OH butyl, JWH-250 4-OH pentyl, AM-2201 4-OH pentyl, JWH-122 5-OH pentyl, JWH-210 5-OH pentyl, 5F-AKB-48 (N-4 OH pentyl), 5F-PB-22 3-carboxyindole)in urine using LLE and LC-MS/MS. The method was validated according to the standard practices for method validation in forensic toxicology (SWGTOX, May 2013). All analytes gave acceptable precision, linearity and recovery for analysing blood and urine samples. The method was applied to 1,496 biological samples, a mixture of whole blood and urine. Blood and/or urine samples were analysed from 114 patients presenting at Accident and Emergency in Glasgow Royal Infirmary, in spring 2014 and JuneDecember 2015. 5F-AKB-48, 5F-PB-22 and MDMB-CHMICA were detected in 9, 7 and 9 cases respectively. 904 urine samples from individuals admitted to/liberated from Scottish prisons over November 2013 were tested for the presence of SCs. 5F-AKB-48 (N-4 OH pentyl) was detected in 10 cases and 5F-PB-22 3-carboxyindole in 3 cases. Blood and urine samples from two post-mortem cases in Scotland with suspected ingestion of SCs were analysed. Both cases were confirmed positive for 5F-AKB-48. A total of 463 urine samples were collected from personnel who presented to the Security Forces Hospital in Ryiadh for workplace drug testing as a requirement for their job during July 2014. The results of the analysis found 2 samples to be positive for 5F-PB-22 3carboxyindole. A further study in Saudi Arabia using a questionnaire was carried out among 3 subpopulations: medical professionals, members of the public in and around smoking cafes and known drug users. With regards to general awareness of Spice products, 16%, 11% and 22% of those participants of medical professionals, members of the public in and around smoking cafes and known drug users, respectively, were aware of the existence of SCs or Spice products. The respondents had an overall average of 4.5% who had a friend who used these Spice products. It is clear from the results obtained in both blood and urine testing and surveys that SCs are being used in both Scotland and Saudi Arabia. The extent of their use is not clear and the data presented here is an initial look into their prevalence. Blood and urine findings suggest changing trends in SC use, moving away from JWH and AM SCs to the newer 5F-AKB-48, 5-F-PB-22 and MDMBCHMICA compounds worldwide. In both countries 5F-PB-22 was detected. These findings clarify how the SCs phenomenon is a worldwide problem and how the information of every country regarding what SCs are seized can help and is not specific for that country. The analytes included in the method were selected due to their apparent availability in both countries, however it is possible that some newer analytes have been used and these would not have been detected. For this reason it is important that methods for testing SCs are updated regularly and evolve with the ever-changing availability of these drugs worldwide. In addition, there is little published literature regarding the concentrations of these drugs found in blood and urine samples and this work goes some way towards understanding these.