The use of enzyme catalysts in organic media for the synthesis of biodegradable polyesters

The enzyme catalysed polytransesterification of diesters with diols was investigated under various conditions. The most consistent results were obtained using crude porcine pancreatic lipase (PPL) suspended in anhydrous diethyl ether. Addition of molecular sieve to the above system gave higher molecular weight products. The PPL catalysed reaction of bis(2,2,2-trichlorethyl) adipate and glutarate with butane-1,4-diol in anhydrous ether with and without molecular sieve was investigated over a range of times from 8 to 240 hours. The 72 hour adipate reaction with molecular sieve gave the highest molecular weight polymer (Mn 6,500 and Mw 9,400). The glutarate gave the maximum molecular weight polyester after 24 hours (Mn 5,700 and Mw 9,500). Occasionally the glutarate reaction produced very high molecular weight polyester-enzyme complexes. Toluene generally gave lower molecular weight products than diethyl ether. Dichloromethane and tetrahydrofuran gave mainly dimers and trimers. Alternative enzyme and diol systems were also investigated. These yielded no polymeric products. The molecular weights of the polyesters were determined by 1H NMR end-group analysis and by GPC. The molecular weights determined by NMR were on average about twice as great as those determined by GPC. The synthesis of the following diesters is described: i)Bis(2,2,2-trichloroethyl) succinate, glutarate, adipate, trans-3-hexenedioate, and trans-3,4-epoxyadipate. ii) Diphenyl glutarate and adipate.iii)Bis(2,2,2-fluoroethyl) glutarate and trans-3-hexendioate.iv) Divinyl glutarate. v) N,N'Glutaryl dicyclohexanone oxime.The polytransesterification of all the above esters with diols was investigated. The easily synthesised bis(2,2,2-trichloroethyl) glutarate and adipate gave the best results and the work was concentrated on these two esters.

Electrospinning pH-responsive block copolymer nanofibers

Electrospinng of a fibrous triblock copolymer consisting of poly(methyl methacrylate-block-poly[2-(diethylamino) ethyl methacrylate]-block-poly(methyl methacrylate) (PMMA-b-PDEA-b-PMMA) has been discussed. A mixed co-solvent system of tetrahydrofuran (THF) and dimethylformamide (DMF) was used to electrospin fibrous PMMA-b-PDEA-b-PMMA and its influence on surface morphology and diameter of the electrospun fiber was also investigated in an attempt to control the fiber diameter. The concentration range between 20 and 40 wt % was found suitable for electrospinning of PMMA-b-PDEA-b-PMMA in a THF/DMF system. It was also observed that the average fiber diameter decreased as the content of DMF was increased. A significant decrease in fiber diameter was observed when moving from a THF solution to a THF/DMF system at a ratio of 70:30.

Controlled growth of poly(2-(diethylamino)ethyl methacrylate) brushes via atom transfer radical polymerisation on planar silicon surfaces

Progress in making pH-responsive polyelectrolyte brushes with a range of different grafting densities is reported. Polymer brushes of poly(2-(diethylamino)ethyl methacrylate) were synthesised via atom transfer radical polymerisation on silicon wafers using a 'grafted from' approach. The [11-(2-bromo-2-methyl) propionyloxy]undecyl trichlorosilane initiator was covalently attached to the silicon via silylation, from which the brushes were grown using a catalytic system of copper(I) chloride and pentamethyldiethylenetriamine in tetrahydrofuran at 80°C. X-ray reflectivity was used to assess the initiator surfaces and an upper limit on the grafting density of the polymer was determined. The quality of the brushes produced was analysed using ellipsometry and atomic force microscopy, which is also discussed.

Monte Carlo and molecular dynamics simulations of methane in potassium montmorillonite clay hydrates at elevated pressures and temperatures

The structure and dynamics of methane in hydrated potassium montmorillonite clay have been studied under conditions encountered in sedimentary basin and compared to those of hydrated sodium montmorillonite clay using computer simulation techniques. The simulated systems contain two molecular layers of water and followed gradients of 150 barkm-1 and 30 Kkm-1 up to a maximum burial depth of 6 km. Methane particle is coordinated to about 19 oxygen atoms, with 6 of these coming from the clay surface oxygen. Potassium ions tend to move away from the center towards the clay surface, in contrast to the behavior observed with the hydrated sodium form. The clay surface affinity for methane was found to be higher in the hydrated K-form. Methane diffusion in the two-layer hydrated K-montmorillonite increases from 0.39×10-9 m2s-1 at 280 K to 3.27×10-9 m2s-1 at 460 K compared to 0.36×10-9 m2s-1 at 280 K to 4.26×10-9 m2s-1 at 460 K in Na-montmorillonite hydrate. The distributions of the potassium ions were found to vary in the hydrates when compared to those of sodium form. Water molecules were also found to be very mobile in the potassium clay hydrates compared to sodium clay hydrates. © 2004 Elsevier Inc. All All rights reserved.

CuII chain compound showing a ferromagnetic coupling through triple N1,N2-1,2,4-triazole bridges

[Cu(hyetrz)3](CF3SO3)2·H2O [hyetrz = 4-(2′-hydroxyethyl)-1,2,4-triazole] represents the first structurally characterised ferromagnetically coupled CuII chain compound containing triple N1,N2-1,2,4-triazole bridges. catena-[μ-Tris{4-(2′-hydroxyethyl)-1,2,4-triazole-N1,N2}copper(II)] bis(trifluoromethanesulfonate) hydrate (C14H23F6S2O10CuN9) crystallises in the triclinic space group Pl, a = 13.54(3), b = 14.37(3), c = 15.61(4) Å, α = 95.9(1), β = 104.9(1), γ = 106.5(1)°, V = 2763(11) Å3, Z = 4 (CuII units). The CuII ions are linked by triple N1,N2-1,2,4-triazole bridges yielding an alternating chain with Cu1−Cu2 = 3.8842(4) Å and Cu2−Cu3 = 3.9354(4) Å. Analysis of the magnetic data according to a high-temperature series expansion gives a J value of +1.45(3) cm−1. The nature and the magnitude of the ferromagnetic exchange have been discussed on the basis of the structural features. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

Novel analytical methodologies for the monitoring of traditional and non-traditional pollutants in different environmental compartments of South Florida

Routine monitoring of environmental pollution demands simplicity and speed without sacrificing sensitivity or accuracy. The development and application of sensitive, fast and easy to implement analytical methodologies for detecting emerging and traditional water and airborne contaminants in South Florida is presented. A novel method was developed for quantification of the herbicide glyphosate based on lyophilization followed by derivatization and simultaneous detection by fluorescence and mass spectrometry. Samples were analyzed from water canals that will hydrate estuarine wetlands of Biscayne National Park, detecting inputs of glyphosate from both aquatic usage and agricultural runoff from farms. A second study describes a set of fast, automated LC-MS/MS protocols for the analysis of dioctyl sulfosuccinate (DOSS) and 2-butoxyethanol, two components of Corexit®. Around 1.8 million gallons of those dispersant formulations were used in the response efforts for the Gulf of Mexico oil spill in 2010. The methods presented here allow the trace-level detection of these compounds in seawater, crude oil and commercial dispersants formulations. In addition, two methodologies were developed for the analysis of well-known pollutants, namely Polycyclic Aromatic Hydrocarbons (PAHs) and airborne particulate matter (APM). PAHs are ubiquitous environmental contaminants and some are potent carcinogens. Traditional GC-MS analysis is labor-intensive and consumes large amounts of toxic solvents. My study provides an alternative automated SPE-LC-APPI-MS/MS analysis with minimal sample preparation and a lower solvent consumption. The system can inject, extract, clean, separate and detect 28 PAHs and 15 families of alkylated PAHs in 28 minutes. The methodology was tested with environmental samples from Miami. Airborne Particulate Matter is a mixture of particles of chemical and biological origin. Assessment of its elemental composition is critical for the protection of sensitive ecosystems and public health. The APM collected from Port Everglades between 2005 and 2010 was analyzed by ICP-MS after acid digestion of filters. The most abundant elements were Fe and Al, followed by Cu, V and Zn. Enrichment factors show that hazardous elements (Cd, Pb, As, Co, Ni and Cr) are introduced by anthropogenic activities. Data suggest that the major sources of APM were an electricity plant, road dust, industrial emissions and marine vessels.

Alquilação de tolueno com propeno, através de complexo ferro (II) ᵦ- diimina homogêneo e heterogeneizado em MCM-41, Al-MCM-41 e SBA-15

This work describes the synthesis and aplication of homogeneous and heterogenized iron catalysts in the alkylation reaction of toluene with propene, empolying experimental design. The homogenous complex was obtained trough the synthesis of the organic ligand folowed by the complexation of the iron(II) chloride. As to the heterogenized complexes, first were synthetized the inorganic supports (SBA-15, MCM-41 and Al-MCM-41). Then, it was synthetized the ligand again, that through funcionalization with chloropropyltrimethoxysilane (CPTMS), was anchored on the support previously calcinated. To these anchored ligands, was complexed the iron(II) chloride, previously solubilizated in tetrahydrofuran (THF). The organic ligand characterization was accomplished trough nuclear magnetic resonance (NMR) and Infrared spectroscopy (IV). The supports were characterized with x-ray diffraction (DRX), texture analysis with nitrogen adsorption/desorption (before and after the anchoring), termogravimetric analysis (TG) and infrared (IV). The metalic content was quantified trough the atomic absorption spectrophotometry (AAS). The complexes were tested in catalytic reactions emolying ethylaluminium sesquichloride (EASC) as co-catalyst in steel reactor, under mecanic stirring. The reaction conditions ranged from 4 to 36 ◦C, with many aluminum/iron ratios. The catalysts were actives in homogeneous and heterogenized ways. The homogenous catalytic complex showed a maximum turnover frequency (TOF) of 8.63 ×103 · h −1 , while, in some conditions, the anchored complexes showed better results, with TOF of until 8.08 ×103 · h −1 . Aditionally, it was possible to determine an equation, to the homogenous catalyst, that describes the product quantity in function of reacional temperature and aluminum/iron ratio.

Utilização da cinza da casca de arroz em cimentação de poços de petróleo

Pozzolanic materials such as rice husk ash are widely used to substitute part of cement, because they react with calcium hydroxide (CH) producing calcium silicate hydrate (C-S-H), which aggregate better physical, chemical and mechanical properties to the cement slurry. The usage of rice husk biomass ash from agribusiness in addition to or partially replacing cement is a noble purpose and a good way of sustainable development which currently is an obsession around the world. The ashes utilized in this study were characterized by: scanning electron microscopy technique (SEM), Fourier transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX) and BET method. The pozzolanic activity of RHA and WRHA in cement slurries was evaluated by: thermal-gravimetric technique and derivative thermogravimetry (TGA/DTG), X-ray diffraction (XRD) and Compressive Strength. The slurries formulated with additions of 10% and 20% of RHA and WRHA were cured for 28 days at 58 °C. The results of thermal analysis demonstrated that a 20% WRHA addition caused a reduction of approximately 73% of Portlandite (calcium hydroxide – CH) phase related to standard slurry (STD). The XRD scans also demonstrated the reduction of the Portlandite peaks’ intensity for each slurry compared with STD slurry. The RHA and WRHA react chemically with Portlandite producing calcium silicate hydrate (C-S-H), confirming their effect as a pozzolanic agent. The WRHA presented the best results as a pozzolanic material.

Investigations of artificial sediments from two deep-sea in situ recolonization experiments deployed for one year at the central HAUSGARTEN station IV during ARK-XIX/3c

Commercial exploitation and abrupt changes of the natural conditions may have severe impacts on the Arctic deep-sea ecosystem. The present recolonisation experiment mimicked a situation after a catastrophic disturbance (e.g. by turbidites caused by destabilized continental slopes after methane hydrate decomposition) and investigated if the recolonisation of a deep-sea habitat by meiobenthic organisms is fostered by variations innutrition and/or sediment structure. Two "Sediment Tray Free Vehicles" were deployed for one year in summer 2003 at 2500 m water depth in the Arctic deep-sea in the eastern Fram Strait. The recolonisation trays were filled with different artificial and natural sediment types (glass beads, sand, sediment mixture, pure deep-sea sediment) and were enriched with various types of food (algae, yeast, fish). After one year, meiobenthos abundances and various sediment related environmental parameters were investigated. Foraminifera were generally the most successful group: they dominated all treatments and accounted for about 87% of the total meiobenthos. Colonizing meiobenthos specimens were generally smaller compared to those in the surrounding deep-sea sediment, suggesting an active recolonisation by juveniles. Although experimental treatments with fine-grained, algae-enriched sediment showed abundances closest to natural conditions, the results suggest that food availability was the main determining factor for a successful recolonisation by meiobenthos and the structure of recolonised sediments was shown to have a subordinate influence.

Data on the biogeochemical cycle of methane in the ocean

Geological, mineralogical and microbiological aspects of the methane cycle in water and sediments of different areas in the oceans are under consideration in the monograph. Original and published estimations of formation- and oxidation rates of methane with use of radioisotope and isotopic methods are given. The role of aerobic and anaerobic microbial oxidation of methane in production of organic matter and in formation of authigenic carbonates is considered. Particular attention is paid to processes of methane transformation in areas of its intensive input to the water column from deep-sea hydrothermal sources, mud volcanoes, and cold methane seeps.

Gas analysis of sediment cores from the Batumi seep area

Detailed knowledge of the extent of post-genetic modifications affecting shallow submarine hydrocarbons fueled from the deep subsurface is fundamental for evaluating source and reservoir properties. We investigated gases from a submarine high-flux seepage site in the anoxic Eastern Black Sea in order to elucidate molecular and isotopic alterations of low-molecular-weight hydrocarbons (LMWHC) associated with upward migration through the sediment and precipitation of shallow gas hydrates. For this, near-surface sediment pressure cores and free gas venting from the seafloor were collected using autoclave technology at the Batumi seep area at 845 m water depth within the gas hydrate stability zone. Vent gas, gas from pressure core degassing, and from hydrate dissociation were strongly dominated by methane (>99.85 mol.% of Sum[C1-C4, CO2]). Molecular ratios of LMWHC (C1/[C2 + C3] > 1000) and stable isotopic compositions of methane (d13C = -53.5 per mill V-PDB; D/H around -175 per mill SMOW) indicated predominant microbial methane formation. C1/C2+ ratios and stable isotopic compositions of LMWHC distinguished three gas types prevailing in the seepage area. Vent gas discharged into bottom waters was depleted in methane by >0.03 mol.% (Sum[C1-C4, CO2]) relative to the other gas types and the virtual lack of 14C-CH4 indicated a negligible input of methane from degradation of fresh organic matter. Of all gas types analyzed, vent gas was least affected by molecular fractionation, thus, its origin from the deep subsurface rather than from decomposing hydrates in near-surface sediments is likely. As a result of the anaerobic oxidation of methane, LMWHC in pressure cores in top sediments included smaller methane fractions [0.03 mol.% Sum(C1-C4, CO2)] than gas released from pressure cores of more deeply buried sediments, where the fraction of methane was maximal due to its preferential incorporation in hydrate lattices. No indications for stable carbon isotopic fractionations of methane during hydrate crystallization from vent gas were found. Enrichments of 14C-CH4 (1.4 pMC) in short cores relative to lower abundances (max. 0.6 pMC) in gas from long cores and gas hydrates substantiates recent methanogenesis utilizing modern organic matter deposited in top sediments of this high-flux hydrocarbon seep area.

Gas hydrates of nonpressurized (GC) and pressurized (DAPC) sediment cores from the Hakon Mosby Mud Volcano, SW Barents Sea

The occurrence of gas hydrates at submarine mud volcanoes (MVs) located within the gas hydrate stability zone (GHSZ) is controlled by upward fluid and heat flux associated with MV activity. Determining the spatial distribution of gas hydrates at MVs is crucial to evaluate their sensitivity to known episodic changes in volcanic activity. We determined the hydrocarbon inventory and spatial distribution of hydrates at an individual MV structure. The Håkon Mosby Mud Volcano (HMMV), located at 1,250 m water depth on the Barents Sea slope, was investigated by combined pressure core sampling, heat flow measurements, and pore water chemical analysis. Quantitative pressure core degassing revealed gas-sediment ratios between 3.1 and 25.7, corresponding to hydrate concentrations of up to 21.3% of the pore volume. Hydrocarbon compositions and physicochemical conditions imply that gas hydrates incipiently crystallize as structure I hydrate, with a dissociation temperature of around 13.8°C at this water depth. Based on numerous in situ measurements of the geothermal gradient in the seabed, pore water sulfate profiles and microbathymetric data, we show that the thickness of the GHSZ increases from less than 1 m at the warm center to around 47 m in the outer parts of the HMMV. We estimate the total mass of hydrate-bound methane stored at the HMMV to be about 102.5 kt, of which 2.8 kt are located within the morphological Unit I around the center and thus are likely to be dissociated in the course of a large eruption.

Ex situ sulphate reduction and methane oxidation rates of sediment at the rim of a vesicomyd clam colony in the Japan Deep Sea Trench (dive 956)

Sediment samples were collected from the rim of a large vesicomyid clam colony in the Japan Deep Sea Trench. Immediately after sample recovery onboard, the sediment core was sub-sampled for ex situ rate measurements. Sulfate reduction and anaerobic oxidation of methane were measured ex situ by the whole core injection method with three replicate measurements for each method. We incubated the samples at in situ temperature (1.5°C) for 48 hours with either 14C-methane (dissolved in water, 2.5 kBq) or carrier-free 35S-sulfate (dissolved in water, 50 kBq). Sediment was fixed in 25 ml sodium hydroxide (NaOH) solution (2.5%, w/v) or 20 ml ZnAc solution (20%, w/v) for AOM or SR, respectively. Turnover rates were measured as previously described (Kallmeyer et al., 2004; Treude et al., 2003).