Strong P.J.,Scion Research |
Claus H.,Johannes Gutenberg University Mainz
Critical Reviews in Environmental Science and Technology | Year: 2011
Laccases are multicopper proteins that use molecular oxygen to oxidize a broad spectrum of organic compounds by a radical-catalyzed reaction mechanism. Many articles over the past 15 years have touted the diverse potential applications of laccase in various biotechnological processes. This review covers the natural roles of the enzyme, its structural properties, substrates, reaction mechanism, and inhibitors, as well as its applications regarding the detoxification and bioremediation of polluted wastewaters and soils. Other applications are briefly covered as well. The authors critically assess the advantages, shortcomings, and future needs relating to laccase availability, effectiveness, and cost-efficiency, and also provide numerous references to the many divisions of research into this multifaceted enzyme © Taylor & Francis Group, LLC.
Donaldson L.A.,Scion Research |
Paul Knox J.,University of Leeds
Plant Physiology | Year: 2012
The distribution of noncellulosic polysaccharides in cell walls of tracheids and xylem parenchyma cells in normal and compression wood of Pinus radiata, was examined to determine the relationships with lignification and cellulose microfibril orientation. Using fluorescence microscopy combined with immunocytochemistry, monoclonal antibodies were used to detect xyloglucan (LM15), β(1,4)-galactan (LM5), heteroxylan (LM10 and LM11), and galactoglucomannan (LM21 and LM22). Lignin and crystalline cellulose were localized on the same sections used for immunocytochemistry by autofluorescence and polarized light microscopy, respectively. Changes in the distribution of noncellulosic polysaccharides between normal and compression wood were associated with changes in lignin distribution. Increased lignification of compression wood secondary walls was associated with novel deposition of β(1,4)-galactan and with reduced amounts of xylan and mannan in the outer S2 (S2L) region of tracheids. Xylan and mannan were detected in all lignified xylem cell types (tracheids, ray tracheids, and thickwalled ray parenchyma) but were not detected in unlignified cell types (thin-walled ray parenchyma and resin canal parenchyma). Mannan was absent from the highly lignified compound middle lamella, but xylan occurred throughout the cell walls of tracheids. Using colocalization measurements, we confirmed that polysaccharides containing galactose, mannose, and xylose have consistent correlations with lignification. Low or unsubstituted xylans were localized in cell wall layers characterized by transverse cellulose microfibril orientation in both normal and compression wood tracheids. Our results support the theory that the assembly of wood cell walls, including lignification and microfibril orientation, may be mediated by changes in the amount and distribution of noncellulosic polysaccharides. © 2011 American Society of Plant Biologists.
Sandquist D.,Scion Research
Appita Journal | Year: 2013
Microfibrillated cellulose (MFC), also known as nanocellulose, is acquired by chemical or mechanical means from a pure cellulose raw material, predominately as a thixotropic hydrogel. Currently it is produced at pilot plant scale, with ongoing efforts for commercial scale production. Current world wide pilot plant investment is approximately NZ$ 50M with a combined capacity of 150 tonnes annually, with plants in Sweden, Finland, Germany, Japan and the US. In addition there are related cellulose whiskers and nanocrystalline cellulose pilot plants coming on-line. Nanocellulose material is potentially an important future revenue stream for pulp producers. The interest in MFC adoption is to utilize its outstanding optical, gas barrier, strength and thermal stability properties to create high value products from potentially low value raw material. The basic technology and material has been known since the beginning of the 1980's, but high energy cost and lack of clear applications has until recently hampered its widespread adoption. Outstanding technical challenges include irreversible agglomeration upon dewatering, substrate and matrix compatibility. This review summarises recent progress in MFC research, specifically highlighting progress in overcoming dispersion and unintentional agglomeration issues. In addition it discusses potential applications of MFC in packaging.
Rindel J.H.,Scion Research
Acta Acustica united with Acustica | Year: 2013
The ERATO project was a three-year research project financed by the European Commission under the Fifth Framework INCO-MED Program (2003-2006). The acronym refers to the project title: Identification, Evaluation and Revival of the Acoustical Heritage of Ancient Theatres and Odea. The ancient Greek and Roman theatres are famous for their excellent acoustics. However, it is not generally well known that different kinds of theatres were built, for different purposes and with different acoustical conditions. The development of the Roman theatre types (theatre, odeon and amphitheatre) particularly in the first Century BC is briefly outlined. One aim of the ERATO project has been to investigate the acoustics of the open air theatre and the odeon, using virtual reconstructions be means of computer models of the spaces, completed in accordance with available archaeological information. Musical instruments and short pieces of music have been reconstructed and recordings have been used for auralisation of some theatre scenarios. Ancient Greek and Roman theatres are often considered acoustically perfect. However, the semicircular shape of the audience area in theatres may cause acoustic problems, and there is also evidence that the ancient architects were aware of this. The Roman architect Vitruvius mentions in his famous books on architecture four different kinds of sound reflections in a theatre, one of them called 'circumsonant' which is probably the acoustical phenomenon that we today would name a focused echo. Computer simulations of some examples of ancient Greek and Roman theatres confirm that echo can occur at some places in the audience area. A possible solution to these echo problems could be the introduction of sound absorption in the vertical, concave surfaces in a way similar to that described by Vitruvius for the sounding vessels, i.e. in niches between the seats arranged in a horizontal range halfway up (in the diazoma). Thus it makes sense if the vessels were supposed to act as sound absorbing resonators, although the number of resonators is far from sufficient for having any real effect. The idea and principle of installing resonators in a theatre comes from Aristoxenus (4th century BC), who was a famous Greek philosopher and scholar in music theory. It is concluded that the sounding vessels had no practical importance in the Roman theatres, and Vitruvius was not up-to-date in his writing on theatre design, but relied heavily on older, Greek references. © S. Hirzel Verlag · EAA.
Multiple pathways of the reaction of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) with (+)-catechin: Evidence for the formation of a covalent adduct between DPPH and the oxidized form of the polyphenol
Osman A.M.,Scion Research
Biochemical and Biophysical Research Communications | Year: 2011
The pathways of the reaction of 2,2-diphenyl picrylhydrazyl radicals (DPPH ) with (+)-catechin were studied in alcoholic solvents. The reaction mixtures were analysed by using reversed-phase liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MS). The intermediate o-quinone of catechin, yellow dimers, trimers and, interestingly, an adduct of the oxidized form of catechin with DPPH radicals were identified. The mass of this adduct was 681Da, suggesting that one molecule of the DPPH radical complexes with the oxidized form of catechin. It is concluded that once the intermediate o-quinone is formed, the reaction proceeds in two pathways, either the o-quinone reacts with catechin to form a hydrophilic dimer (type B), which is further oxidized to hydrophobic dimers (type A) and consequently to oligomers of higher molecular weights; or the A-ring of the o-quinone is further oxidized by a DPPH radical and that this oxidized intermediate then reacts with another DPPH radical to form the observed adduct. The identification of the latter mechanism could explain the contradictory results reported in the literature for the reaction of polyphenols with DPPH radicals. © 2011 Elsevier Inc.