Pyrolysis GC–MS as a novel analysis technique to determine the biochemical composition of microalgae

The biochemical composition of microalgae is a major factor in the feasibility of microalgae biofuel systems. Currently full compositional analysis entails tedious, costly and time consuming analysis methods. In the current research, an attempt has been made to use Analytical Pyrolysis Gas Chromatography Mass Spectrometry (Py–GC–MS) to determine the biochemical composition of microalgae. By identifying pyrolysis marker compounds of each main biochemical component of microalgae, the composition of algae samples could be estimated. This was aided by performing Py–GC–MS of a model protein, carbohydrate and lipid. Indole was shown to be a decomposition product from the protein fraction and its levels were consistent with the changing protein content. The lipid content of the microalgae could be estimated from the presence of alkanes and the carbohydrate fraction by the presence of 1,2-cyclopentanedione, 3-methyl-. A total of 26 different microalgae and cyanobacteria strains were investigated for their protein, carbohydrate and lipid levels using established analysis techniques. The biochemical compositions are compared to the results from the novel technique using Py–GC–MS and are shown to correspond well; R2 values were found to be 0.6–0.9. The results suggest that Py–GC–MS can be used as a rapid test for studying levels and changes in biochemical composition of different algae using one fast technique with minimal sample preparation

Hydrothermal microwave processing of microalgae as a pre-treatment and extraction technique for bio-fuels and bio-products

Microalgae are regarded as a promising source of lipids for bio-diesel production and bio-products. The current paper investigates the processing of microalgal slurries under controlled microwave irradiation. Microwave power was applied to reach temperatures of 80, 100, 120 and 140. °C at a constant residence time of 12. min. Microwave irradiation led to disruption of the algal cell walls which facilitated lipid extraction. The influence of inorganic material on microwave heating was assessed for three strains including, Nannochloropsis occulata, Chlorogloeopsis fritschii and Pseudochoricystis ellipsoidea. Mass balances were calculated and showed that the amount of carbon, nitrogen and total mass recovered in the residue was highly dependent on process conditions and algae strain. Hydrothermal microwave processing (HMP) was found to be an effective pre-treatment for hydrothermal liquefaction and extraction of lipids and phytochemicals

The seasonal variation of fucoidan within three species of brown macroalgae

Fucoidan is comprised of a fucose backbone with sulphate groups, whose variation is important to the functionality of the polysaccharide. The structure of fucoidan has been reported to vary according to species, season, location and maturity; however there is currently little published data to support this. Understanding the seasonal variation of fucoidan is important for industrial applications to identify optimum harvesting times and ensure consistent product composition. This study explores the seasonal variation of three species of brown macroalgae, Fucus serratus (FS), Fucus vesiculosus (FV) and Ascophyllum nodosum (AN), harvested monthly off the coast of Aberystwyth, UK. Average fucoidan content is 6.0, 9.8 and 8.0 wt% respectively for FS, FV and AN, with highest quantities extracted in autumn and lowest in spring. Fucose content, varied between 18 and 28, 26–39 and 35–46 wt% and sulphate content between 30 and 40, 9–35 and 6–22 wt% for FS, FV and AN respectively, with both fluctuating inversely to the total fucoidan content. Size exclusion chromatography (SEC) has provided insight into the structural differences between the species. Based on the molecular weight (MW) distribution, and in line with previous research, it is hypothesised that fucoidan in FS has a more complex structure, with a higher degree of associated sulphate ions than in FV and AN which have a simpler, linear structure with less associated sulphate ions

Hot Gas Structure in the Elliptical Galaxy NGC 4472

We present X-ray spectroscopic and morphological analyses using Chandra ACIS and ROSAT observations of the giant elliptical galaxy NGC 4472 in the Virgo cluster. We discuss previously unobserved X-ray structures within the extended galactic corona. In the inner 2' of the galaxy, we find X-ray holes or cavities with radii of ~2 kpc, corresponding to the position of radio lobes. These holes were produced during a period of nuclear activity that began 1.2 x 10^7 years ago and may be ongoing. We also find an asymmetrical edge in the galaxy X-ray emission 3' (14 kpc) northeast of the core and an ~8' tail (36 kpc) extending southwest of the galaxy. These two features probably result from the interaction of NGC 4472 gas with the Virgo gas, which produces compression in the direction of NGC 4472's infall and an extended tail from ram pressure stripping. Assuming the tail is in pressure equilibrium with the surrounding gas, we compute its angle to our line of sight and estimate that its true extent exceeds 100 kpc. Finally, in addition to emission from the nucleus (first detected by Soldatenkov, Vikhlinin & Pavlinsky), we detect two small extended sources within 10'' of the nucleus of the galaxy, both of which have luminosities of ~7 x 10^38 erg/s.Comment: 25 pages, 11 figures, accepted by Ap

Ingested foreign bodies and societal wealth: three year observational study of swallowed coins

Objective To examine the relation between coins ingested by children and the Dow Jones Industrial Average

Hydrogen production from the catalytic supercritical water gasification of process water generated from hydrothermal liquefaction of microalgae

The integration of hydrothermal liquefaction (HTL) and hydrothermal gasification (HTG) is an option for enhanced energy recovery and potential biocrude upgrading. The yields and product distribution obtained from the HTL of Chlorella vulgaris have been investigated. High conversion of algae to biocrude as well as near complete gasification of the remaining organic components in the aqueous phase was achieved. The aqueous phase from HTL was upgraded through catalytic HTG under supercritical water conditions to maximise hydrogen production for biocrude hydrotreating. High yields of hydrogen were produced (∼30 mol H2/kg algae) with near complete gasification of the organics (∼98%). The amount of hydrogen produced was compared to the amounts needed for complete hydrotreating of the biocrude. A maximum of 0.29 g H2 was produced through HTG per gram of biocrude produced by HTL. The nutrient content of the aqueous phase was analysed to determine suitability of nutrient recovery for algal growth. The results indicate the successful integration of HTL and HTG to produce excess hydrogen and maintain nutrient recovery for algal growth

Cascading on extragalactic background light

High-energy gamma-rays propagating in the intergalactic medium can interact with background infrared photons to produce e+e- pairs, resulting in the absorption of the intrinsic gamma-ray spectrum. TeV observations of the distant blazar 1ES 1101-232 were thus recently used to put an upper limit on the infrared extragalactic background light density. The created pairs can upscatter background photons to high energies, which in turn may pair produce, thereby initiating a cascade. The pairs diffuse on the extragalactic magnetic field (EMF) and cascade emission has been suggested as a means for measuring its intensity. Limits on the IR background and EMF are reconsidered taking into account cascade emissions. The cascade equations are solved numerically. Assuming a power-law intrinsic spectrum, the observed 100 MeV - 100 TeV spectrum is found as a function of the intrinsic spectral index and the intensity of the EMF. Cascades emit mainly at or below 100 GeV. The observed TeV spectrum appears softer than for pure absorption when cascade emission is taken into account. The upper limit on the IR photon background is found to be robust. Inversely, the intrinsic spectra needed to fit the TeV data are uncomfortably hard when cascade emission makes a significant contribution to the observed spectrum. An EMF intensity around 1e-8 nG leads to a characteristic spectral hump in the GLAST band. Higher EMF intensities divert the pairs away from the line-of-sight and the cascade contribution to the spectrum becomes negligible.Comment: 5 pages, to be published as a research note in A&

Observers and Measurements in Noncommutative Spacetimes

We propose a "Copenhagen interpretation" for spacetime noncommutativity. The goal is to be able to predict results of simple experiments involving signal propagation directly from commutation relations. A model predicting an energy dependence of the speed of photons of the order E/E_Planck is discussed in detail. Such effects can be detectable by the GLAST telescope, to be launched in 2006.Comment: 10 pp; v2: equivalence of observers explicitely stated; v3: minor changes, references and remarks added, burst spreading with energy emphasized as a signature rather than nois