Composition and accumulatein rates of bottom sediments from Core PS1599-3, Continental Slope of the Weddell Sea

Genetic sediment types have been identified based on a study of Core PS1599 collected from the eastern continental slope of the Weddell Sea. XRF analysis of 48 samples from this core carried out at the Vernadsky Institute of Geochemistry and Analytical Chemistry (Moscow) yielded the first comprehensive geochemical characteristics of all genetic types. Methods of correlation and factor analyses were used to outline geochemical associations of sediments and examine causes of their formation including the role of grain size composition. The results obtained have revealed fundamental differences between sources, mechanisms, and methods of transportation of sedimentary material for Holocene sediments, on the one hand, and Weichselian sediments, on the other hand.

Synthesis dataset of physical and ecosystem properties from pan-arctic wetland sites using peat core analysis

Permafrost dynamics play an important role in high-latitude peatland carbon balance and are key to understanding the future response of soil carbon stocks. Permafrost aggradation can control the magnitude of the carbon feedback in peatlands through effects on peat properties. We compiled peatland plant macrofossil records for the northern permafrost zone (515 cores from 280 sites) and classified samples by vegetation type and environmental class (fen, bog, tundra and boreal permafrost, thawed permafrost). We examined differences in peat properties (bulk density, carbon (C), nitrogen (N) and organic matter content, C/N ratio) and C accumulation rates among vegetation types and environmental classes.

A synthesis of dominant ecological processes in intensive shrimp ponds and adjacent coastal environments in NE Australia

One of the key environmental concerns about shrimp farming is the discharge of waters with high levels of nutrients and suspended solids into adjacent waterways. In this paper we synthesize the results of our multidisciplinary research linking ecological processes in intensive shrimp ponds with their downstream impacts in tidal, mangrove-lined creeks. The incorporation of process measurements and bioindicators, in addition to water quality measurements, improved our understanding of the effect of shrimp farm discharges on the ecological health of the receiving water bodies. Changes in water quality parameters were an oversimplification of the ecological effects of water discharges, and use of key measures including primary production rates, phytoplankton responses to nutrients, community shifts in zooplankton and delta(15)N ratios in marine plants have the potential to provide more integrated and robust measures. Ultimately, reduction in nutrient discharges is most likely to ensure the future sustainability of the industry. (C) 2003 Elsevier Ltd. All rights reserved.

Organic reactions in ionic liquids:Gewald synthesis of 2-aminothiophenes catalyzed by ethylenediammonium diacetate

Ionic liquids based on 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4) and 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) were used as reusable alternatives to volatile organic solvents (VOCs) for ethylenediammonium diacetate (EDDA) catalyzed Gewald synthesis of 2-aminothiophenes. Significant rate enhancement and improvement of the yield were observed. The ionic liquids containing catalyst EDDA were recycled several times with no decreases in yields and reaction rates.

Functional polymers for biomedical application : synthesis and applications

Aromatic and aliphatic diacid chlorides were used to condense naturally occurring diamino acids and their esterified derivatives. It was anticipated the resulting functional polyamides would biodegrade to physiologically acceptable compounds and show pH dependant solubility could be used for biomedical applications ranging from enteric coatings to hydrosoluble drug delivery vehicles capable of targeting areas of low physiological pH. With these applications in mind the polymers were characterised by infra red spectroscopy, gel permeation chromatography and in the case of aqueous soluble polymers by potentiometric titration. Thin films of poly (lysine ethyl ester isophthalamide) plasticised with poly (caprolactone) were cast from DMSO/chloroform solutions and their mechanical properties measured on a Hounsfield Hti tensiometer. Interfacial synthesis was investigated as a synthetic route for the production of linear functional polyamides. High molecular weight polymer was obtained only when esterified diamino acids were condensed with aromatic diacid chlorides. The method was unsuitable for the production of copolymers of free and esterified amino acids with a diacid chloride. A novel miscible mixed solvent single phase reaction was investigated for production of copolymers of esterified and non-esterified amino acids with diacid chlorides. Aliphatic diacid chlorides were unsuitable for condensing diamino acids using this technique because of high rates of hydrolysis. The technique gave high molecular weight homopolymers from esterified diamino acids and aromatic diacid chlorides.

Synthesis of CuS and CuS/ZnS core/shell nanocrystals for photocatalytic degradation of dyes under visible light

High quality CuS and CuS/ZnS core/shell nanocrystals (NCs) were synthesized in a large quantity using a facile hydrothermal method at low temperatures of 60 C and evaluated in the photodegradation of Rhodamine B (RhB) under visible light irradiation. Synthesis time plays an important role in controlling the morphology, size and photocatalytic activity of both CuS and CuS/ZnS core/shell NCs which evolve from spherical shaped particles to form rods with increasing reaction time, and after 5 h resemble "flower" shaped morphologies in which each "flower" is composed of many NCs. Photocatalytic activity originates from photo-generated holes in the narrow bandgap CuS, with encapsulation by large bandgap ZnS layers used to form the core/shell structure that improves the resistance of CuS towards photocorrosion. Such CuS/ZnS core/shell structures exhibit much higher photocatalytic activity than CuS or ZnS NCs alone under visible light illumination, and is attributed to higher charge separation rates for the photo-generated carriers in the core/shell structure. © 2013 Elsevier B.V.

New solid base catalysts for biodiesel synthesis

The application of heterogeneous catalysts for the manufacture of renewable biodiesel fuels offers an exciting, alternative clean chemical technology to current energy intensive processes employing soluble base catalysts. We recently synthesised tuneable MgO nanocrystals as efficent solid base catalysts for biodiesel synthesis, and have developed a simple X-ray spectroscopic method to quantitatively determine surface basicity, thereby providing a rapid screening tool for predicting the reactivity of new solid base catalysts. Promotion of these MgO nanocrystals through Cs doping dramatically enhances biodiesel production rates due to the formaion of a mixed Cs Mg(CO ) phase. These MgO derived nanocatalysts permit energy efficent, continuous processing of diverse, sustainable oil feedstocks in flow reactors.

I.~Synthesis, isolation, and characterization of 1-(2-anthryl)-2-cyclopropylethylene and 1-(2-naphthyl)-2-cyclopropylethylene. II.~Titanium dioxide photocatalysis of haloethers: A mechanistic study

I. The target molecules are classified as 1-aryl 2-cyclopropyl substituted ethylene. In the ground state, these molecules have a number of conformers, which are in equilibrium through rotation about single bonds. Once excited, the conformers have fixed conformation and are no longer in equilibrium and can be distinguished by their UV-vis as well as fluorescence spectra. The synthetic strategy involves standard steps. Both 2-methylanthracene and 2-methylnaphthalene were brominated using N-bromosuccinimide to give the bromomethyl adduct, which then was reacted with triphenylphosphine to form the phosphonium salt. This was followed by the formation of the phosphorus ylide, which upon treatment with cyclopropanecarboxaldehyde gave the product.^ II. The degradation of three aliphatic haloethers: bis-(2-chloroethyl) ether, bis-(2-chloroisopropyl) ether, and bis-(2-chloroethoxy)methane and two aromatic haloethers: 4-chlorodiphenyl ether and 4-bromodiphenyl ether was studied. Product studies have been conducted on the titanium dioxide photocatalysis of these compounds including mass balance, monitoring and identifying intermediates to establish the reaction pathways to deduce a mechanism for their degradation. The extent of mineralization was determined from the measurement of halogen anion (Cl$\sp-$/Br$\sp-$) as well as total organic carbon. The relative rates of disappearance of the individual haloethers appear to be related to the hydrophobic character of the given compound. Reaction mechanisms involving hydroxyl radical are proposed to explain the observed results. ^

Synthesis of aromatic monothiols and aromatic dithiols to increase the folding rate and yield of disulfide containing proteins

Most pharmaceutically relevant proteins and many extracellular proteins contain disulfide bonds. Formation of the correct disulfide bonds is essential for stability in almost all cases. Disulfide containing proteins can be rapidly and inexpensively overexpressed in bacteria. However, the overexpressed proteins usually form aggregates inside the bacteria, called inclusion bodies, which contains inactive and non-native protein. To obtain native protein, inclusion bodies need to be isolated and resolubilized, and then the resulting protein refolded in vitro. In vitro protein folding is aided by the addition of a redox buffer, which is composed of a small molecule disulfide and/or a small molecule thiol. The most commonly used redox buffer contains reduced and oxidized glutathione. Recently, aliphatic dithiols and aromatic monothiols have been employed as redox buffers. Aliphatic dithiols improved the yield of native protein as compared to the aliphatic thiol, glutathione. Dithiols mimic the in vivo protein folding catalyst, protein disulfide isomerase, which has two thiols per active site. Furthermore, aromatic monothiols increased the folding rate and yield of lysozyme and RNase A relative to glutathione. By combining the beneficial properties of aliphatic dithiols and aromatic monothiols, aromatic dithiols were designed and were expected to increase in vitro protein folding rates and yields. Aromatic monothiols (1-4) and their corresponding disulfides (5-8), two series of ortho- and para-substituted ethylene glycol dithiols (9-15), and a series of aromatic quaternary ammonium salt dithiols (16-17) were synthesized on a multigram scale. Monothiols and disulfides (1-8) were utilized to fold lysozyme and bovine pancreatic trypsin inhibitor. Dithiols (11-17) were tested for their ability to fold lysozyme. At pH 7.0 and pH 8.0, and high protein concentration (1 mg/mL), aromatic dithiols (16, 17) and a monothiol (3) significantly enhanced the in vitro folding rate and yield of lysozyme relative to the aliphatic thiol, glutathione. Additionally, aromatic dithiols (16, 17) significantly enhance the folding yield as compared to the corresponding aromatic monothiol (3). Thus, the folding rate and yield enhancements achieved in in vitro protein folding at high protein concentration will decrease the volume of renaturation solution required for large scale processes and consequently reduce processing time and cost.

Synthesis of aromatic monothiols to increase the folding rate and yields of disulfide-containing proteins

Almost all pharmaceutically relevant proteins and many extracellular proteins contain disulfide bonds, which are essential for protein functions. In many cases, disulfidecontaining proteins are produced via in vitro protein folding that involves the oxidation of reduced protein to native protein, a complex process. The in vitro folding of reduced lysozyme has been extensively studied as a model system because native lysozyme is small, inexpensive, and has only four disulfide bonds. The folding of reduced lysozyme is conducted with the aid of a redox buffer consisting of a small molecule disulfide and a small molecule thiol, such as oxidized and reduced glutathione. Herein, in vitro folding rates and yields of lysozyme obtained in the presence of a series of aromatic thiols and oxidized glutathione are compared to those obtained with reduced and oxidized glutathione. Results showed that aromatic thiols significantly increase the folding rate of lysozyme compared to glutathione.

Lithological and chemical composition, stages of sediment accumulation, and sedimentation rates in Core PSh24-2537, West Gotland Basin, Baltic Sea

We studied the grain-size, mineral and chemical compositions, physical properties, radiocarbon age, spore-pollen spectra, and diatom composition in sediments from Core PSh24-2537 sampled in the West Gotland Basin. Four lithological-stratigraphic units were distinguished: varved clays of the Baltic Ice Lake, black and black-gray (sulfide) clays of the Yoldian Sea, gray clays of Ancylus Lake, and greenish-gray sapropel-like littorine and post-littorine silts of the marine stage of Holocene. These units differ from each other both in their matter composition and in plant remains. In the littorine silts organic carbon concentra¬tion reached from 1.5 to 10.35%. Conditions of sediment accumulation and the stages of evolution of the West Gotland Basin over the post-glacial time are characterized.

(Table 1) Sedimentation rates in the Reykjanes rift near 58° for time intervals 0-11 ka, 11-18 ka, and 18-21 ka

Sedimentation rates in the Reykjanes rift near 58°N have been measured on the base of radiocarbon datings of bottom sediments collected during Cruise 4 of R/V Akademik Mstislav Keldysh.

Chlorophyll-a, primary production rates, carbon concentrations and cell counts of coccolithophores, diatoms and microzooplankton measured in water samples from the North Atlantic during the M87/1 cruise in April 2012

The Deep Convection cruise repeatedly sampled two locations in the North Atlantic, sited in the Iceland and Norwegian Basins, onboard the RV Meteor (19 March - 2 May 2012). Samples were collected from multiple casts of a conductivity-temperature-depth (CTD) - Niskin rosette at each station. Water samples for primary production rates, community structure, chlorophyll a [Chl a], calcite [PIC], particulate organic carbon [POC] and biogenic silicic acid [BSi] were collected from predawn casts from six light depths (55%, 20%, 14%, 7%, 5% and 1% of incident PAR). Additional samples for community structure and ancillary parameters were collected from a second cast. Carbon fixation rates were determined using the 13C stable isotope method. Water samples for diatom and micro zooplankton counts, collected from the predawn casts, were preserved with acidic Lugol's solution (2% final solution) and counted using an inverted light microscope. Water samples for coccolithophore counts were collected onto cellulose nitrate filters and counted using polarising light microscopy. Water samples for Chl a analysis were filtered onto MF300 and polycarbonate filters and extracted in 90% acetone. PIC and BSi samples were filtered onto polycarbonate filters and analysed using an inductively coupled plasma emission optical spectrometer and a SEAL QuAAtro autoanalyser respectively.

The VLT-FLAMES Tarantula Survey XXI. Stellar spin rates of O-type spectroscopic binaries

Context: The initial distribution of spin rates of massive stars is a fingerprint of their elusive formation process. It also sets a key initial condition for stellar evolution and is thus an important ingredient in stellar population synthesis. So far, most studies have focused on single stars. Most O stars are, however, found in multiple systems. 

Aims: By establishing the spin-rate distribution of a sizeable sample of O-type spectroscopic binaries and by comparing the distributions of binary subpopulations with one another and with that of presumed-single stars in the same region, we aim to constrain the initial spin distribution of O stars in binaries, and to identify signatures of the physical mechanisms that affect the evolution of the spin rates of massive stars. 

Methods: We use ground-based optical spectroscopy obtained in the framework of the VLT-FLAMES Tarantula Survey (VFTS) to establish the projected equatorial rotational velocities (ν_esini) for components of 114 spectroscopic binaries in 30 Doradus. The ν_esini values are derived from the full width at half maximum (FWHM) of a set of spectral lines, using a FWHM vs. ν_esini calibration that we derive based on previous line analysis methods applied to single O-type stars in the VFTS sample. 

Results: The overall ν_esini distribution of the primary stars resembles that of single O-type stars in the VFTS, featuring a low-velocity peak (at ν_esini<200 kms^-1) and a shoulder at intermediate velocities (200 <ν_esini<300 kms^-1). The distributions of binaries and single stars, however, differ in two ways. First, the main peak at ν_esini ~ 100kms^-1 is broader and slightly shifted towards higher spin rates in the binary distribution than that of the presumed-single stars. This shift is mostly due to short-period binaries (P_orb~<10 d). Second, the ν_esini distribution of primaries lacks a significant population of stars spinning faster than 300 kms^-1, while such a population is clearly present in the single-star sample. The ν_esini distribution of binaries with amplitudes of radial velocity variation in the range of 20 to 200 kms^-1 (mostly binaries with P_orb ~ 10-1000 d and/or with q<0.5) is similar to that of single O stars below ν_esini_~<170kms^-1. 

Conclusions: Our results are compatible with the assumption that binary components formed with the same spin distribution as single stars, and that this distribution contains few or no fast-spinning stars. The higher average spin rate of stars in short-period binaries may either be explained by spin-up through tides in such tight binary systems, or by spin-down of a fraction of the presumed-single stars and long-period binaries through magnetic braking (or by a combination of both mechanisms). Most primaries and secondaries of SB2 systems with P_orb~<10 d appear to have similar rotational velocities. This is in agreement with tidal locking in close binaries where the components have similar radii. The lack of very rapidly spinning stars among binary systems supports the idea that most stars with ν_esini_~> 300kms^-1 in the single-star sample are actually spun-up post-binary interaction products. Finally, the overall similarities (low-velocity peak and intermediate-velocity shoulder) of the spin distribution of binary and single stars argue for a massive star formation process in which the initial spin is set independently of whether stars are formed as single stars or as components of a binary system.