University of Reading

About: University of Reading is a education organization based out in Reading, United Kingdom. It is known for research contribution in the topics: Population & Climate change. The organization has 18728 authors who have published 46707 publications receiving 1758671 citations. The organization is also known as: University College, Reading.

Effect of Architecture on the Phase Behavior of AB-Type Block Copolymer Melts

Abstract: Equilibrium phase diagrams are calculated for a selection of two-component block copolymer architectures using self-consistent field theory (SCFT) The topology of the phase diagrams is relatively unaffected by differences in architecture, but the phase boundaries shift significantly in composition The shifts are consistent with the decomposition of architectures into constituent units as proposed by Gido and co-workers, but there are significant quantitative deviations from this principle in the intermediate-segregation regime Although the complex phase windows continue to be dominated by the gyroid (G) phase, the regions of the newly discovered Fddd (O70) phase become appreciable for certain architectures and the perforated-lamellar (PL) phase becomes stable when the complex phase windows shift toward high compositional asymmetry

Shifts in metabolic scaling, production, and efficiency across major evolutionary transitions of life

Abstract: The diversification of life involved enormous increases in size and complexity. The evolutionary transitions from prokaryotes to unicellular eukaryotes to metazoans were accompanied by major innovations in metabolic design. Here we show that the scalings of metabolic rate, population growth rate, and production efficiency with body size have changed across the evolutionary transitions. Metabolic rate scales with body mass superlinearly in prokaryotes, linearly in protists, and sublinearly in metazoans, so Kleiber's 3/4 power scaling law does not apply universally across organisms. The scaling of maximum population growth rate shifts from positive in prokaryotes to negative in protists and metazoans, and the efficiency of production declines across these groups. Major changes in metabolic processes during the early evolution of life overcame existing constraints, exploited new opportunities, and imposed new constraints.

Effect of the polyunsaturated fatty acid composition of beef muscle on the profile of aroma volatiles.

Abstract: The effect of n-3 polyunsaturated fatty acids (PUFAs) in beef muscle on the composition of the aroma volatiles produced during cooking was measured. The meat was obtained from groups of steers fed different supplementary fats: (i) a palm-oil-based control; (ii) bruised whole linseed, which increased muscle levels of alpha-linolenic (C18:3 n-3) and eicosapentaenoic acid (EPA, C20:5 n-3); (iii) fish oil, which increased EPA and docosahexaenoic acid (C22:6 n-3); (iv) equal quantities of linseed and fish oil. Higher levels of lipid oxidation products were found in the aroma extracts of all of the steaks with increased PUFA content, after cooking. In particular, n-alkanals, 2-alkenals, 1-alkanols, and alkylfurans were increased up to 4-fold. Most of these compounds were derived from the autoxidation of the more abundant mono- and di-unsaturated fatty acids during cooking, and such autoxidation appeared to be promoted by increased levels of PUFAs.

Iron storage in bacteria.

Abstract: Iron is an essential nutrient for nearly all organisms but presents problems of toxicity, poor solubility and low availability. These problems are alleviated through the use of iron-storage proteins. Bacteria possess two types of iron-storage protein, the haem-containing bacterioferritins and the haem-free ferritins. These proteins are widespread in bacteria, with at least 39 examples known so far in eubacteria and archaebacteria. The bacterioferritins and ferritins are distantly related but retain similar structural and functional properties. Both are composed of 24 identical or similar subunits (approximately 19 kDa) that form a roughly spherical protein (approximately 450 kDa, approximately 120 A diameter) containing a large hollow centre (approximately 80 A diameter). The hollow centre acts as an iron-storage cavity with the capacity to accommodate at least 2000 iron atoms in the form of a ferric-hydroxyphosphate core. Each subunit contains a four-helix bundle which carries the active site or ferroxidase centre of the protein. The ferroxidase centres endow ferrous-iron-oxidizing activity and are able to form a di-iron species that is an intermediate in the iron uptake, oxidation and core formation process. Bacterioferritins contain up to 12 protoporphyrin IX haem groups located at the two-fold interfaces between pairs of two-fold related subunits. The role of the haem is unknown, although it may be involved in mediating iron-core reduction and iron release. Some bacterioferritins are composed of two subunit types, one conferring haem-binding ability (alpha) and the other (beta) bestowing ferroxidase activity. Bacterioferritin genes are often adjacent to genes encoding a small [2Fe-2S]-ferredoxin (bacterioferritin-associated ferredoxin or Bfd). Bfd may directly interact with bacterioferritin and could be involved in releasing iron from (or delivering iron to) bacterioferritin or other iron complexes. Some bacteria contain two bacterioferritin subunits, or two ferritin subunits, that in most cases co-assemble. Others possess both a bacterioferritin and a ferritin, while some appear to lack any type of iron-storage protein. The reason for these differences is not understood. Studies on ferritin mutants have shown that ferritin enhances growth during iron starvation and is also involved in iron accumulation in the stationary phase of growth. The ferritin of Campylobacter jejuni is involved in redox stress resistance, although this does not appear to be the case for Escherichia coli ferritin (FtnA). No phenotype has been determined for E. coli bacterioferritin mutants and the precise role of bacterioferritin in E. coli remains uncertain.