Unravelling the Carbohydrate‐Binding Preferences of the Carbohydrate‐Binding Modules of AMP‐Activated Protein Kinase

The β subunit of adenosine monophosphate (AMP)‐activated protein kinase (AMPK), which exists as two isoforms (β1 and β2) in humans, has a carbohydrate‐binding module (CBM) that interacts with glycogen. Although the β1‐ and β2‐CBMs are structurally similar, with strictly conserved ligand‐contact residues, they show different carbohydrate affinities. β2‐CBM shows the strongest affinity for both branched and unbranched oligosaccharides and it has recently been shown that a Thr insertion into β2‐CBM (Thr101) forms a pocket to accommodate branches. This insertion does not explain why β2‐CBM binds all carbohydrates with stronger affinity. Herein, it is shown that residue 134 (Val for β2 and Thr for β1), which does not come into contact with a carbohydrate, appears to account for the affinity difference. Characterisation by NMR spectroscopy, however, suggests that mutant β2‐Thr101Δ/Val134Thr differs from that of β1‐CBM, and mutant β1‐Thr101ins/Thr134Val differs from that of β2‐CBM. Furthermore, these mutants are less stable to chemical denaturation, relative to that of wild‐type β‐CBMs, which confounds the affinity analyses. To support the importance of Thr101 and Val134, the ancestral CBM has been constructed. This CBM retains Thr101 and Val134, which suggests that the extant β1‐CBM has a modest loss of function in carbohydrate binding. Because the ancestor bound carbohydrate with equal affinity to that of β2‐CBM, it is concluded that residue 134 plays an indirect role in carbohydrate binding.     

Technical and economic analysis of solvent-based lithium-ion electrode drying with water and NMP

Processing lithium-ion battery (LIB) electrode dispersions with water as the solvent during primary drying offers many advantages over N-methylpyrrolidone (NMP). An in-depth analysis of the comparative drying costs of LIB electrodes is discussed for both NMP- and water-based dispersion processing in terms of battery pack $/kWh. Electrode coating manufacturing and capital equipment cost savings are compared for water vs. conventional NMP organic solvent processing. A major finding of this work is that the total electrode manufacturing costs, whether water- or NMP-based, contribute about 8–9% of the total pack cost. However, it was found that up to a 2?×?reduction in electrode processing (drying and solvent recovery) cost can be expected along with a $3–6?M savings in associated plant capital equipment (for a plant producing 100,000 10-kWh Plug-in Hybrid Electric Vehicle (PHEV) batteries) using water as the electrode solvent. This paper shows a different perspective in that the most important benefits of aqueous electrode processing actually revolve around capital equipment savings and environmental stewardship and not processing cost savings.     

Enhancing the carbon sink in European agricultural soils: including trace gas fluxes in estimates of carbon mitigation potential

The possibility that the carbon sink in agricultural soils can be enhanced has taken on great political significance since the Kyoto Protocol was finalised in December 1997. The Kyoto Protocol allows carbon emissions to be offset by demonstrable removal of carbon from the atmosphere. Thus, forestry activities (Article 3.3) and changes in the use of agricultural soils (Article 3.4) that are shown to reduce atmospheric CO₂levels may be included in the Kyoto emission reduction targets. The European Union is committed to a reduction in CO₂ emissions to 92% of baseline (1990) levels during the first commitment period (2008–2012). We have shown recently that there are a number of agricultural land-management changes that show some potential to increase the carbon sink in agricultural soils and others that allow alternative forms of carbon mitigation (i.e. through fossil fuel substitution), but the options differ greatly in their potential for carbon mitigation. The changes examined were, (a) switching all animal manure use to arable land, (b) applying all sewage sludge to arable land, (c) incorporating all surplus cereal straw, (d) conversion to no-till agriculture, (e) use of surplus arable land to de-intensify 1/3 of current intensive crop production (through use of 1/3 grass/arable rotations), (f) use of surplus arable land to allow natural woodland regeneration, and (g) use of surplus arable land for bioenergy crop production. In this paper, we attempt for the first time to assess other (non-CO₂) effects of these land-management changes on (a) the emission of the other important agricultural greenhouse gases, methane and nitrous oxide, and (b) other aspects of the ecology of the agroecosystems. We find that the relative importance of trace gas fluxes varies enormously among the scenarios. In some such as the sewage sludge, woodland regeneration and bioenergy production scenarios, the inclusion of trace gases makes only a small (<10%) difference to the CO₂-C mitigation potential. In other cases, for example the no-till, animal manure and agricultural de-intensification scenarios, trace gases have a large impact, sometimes halving or more than doubling the CO₂-C mitigation potential. The scenarios showing the greatest increase when including trace gases are those in which manure management changes significantly. In the one scenario (no-till) where the carbon mitigation potential was reduced greatly, a small increase in methane oxidation was outweighed by a sharp increase in N₂O emissions. When these land-management options are combined to examine the whole agricultural land area of Europe, most of the changes in mitigation potential are small, but depending upon assumptions for the animal manure scenario, the total mitigation potential either increases by about 20% or decreases by about 10%, shifting the mitigation potential of the scenario from just above the EU's 8% Kyoto emission reduction target (98.9 Tg C y⁻¹) to just below it. Our results suggest that (a) trace gas fluxes may change the mitigation potential of a land management option significantly and should always be considered alongside CO₂-C mitigation potentials and (b) agricultural management options show considerable potential for carbon mitigation even after accounting for trace gas fluxes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Exploring the unique pharmacology of a novel opioid receptor, ZFOR1, using molecular modeling and the `message-address' concept

Previous studies have probed the structural basis of ligandselectivity in the mu, delta and kappa opioid receptors throughthe application of molecular modeling techniques in concertwith the `message–address' concept. Here, this approachwas used in an attempt to rationalize the unique pharmacologicalprofile of a recently cloned novel opioid receptor, ZFOR1 (ZebraFishOpioid Receptor 1). Specifically, a model of the transmembranedomains of ZFOR1 was constructed and used to explore the bindingmodes of various prototypical opioid ligands. The results showthat the `message' portion of the binding pocket of ZFOR1 ishighly conserved; hence, the binding modes of non-selectiveopioid ligands are well preserved. In contrast, a small numberof variant residues at the extracellular end of the bindingpocket, particularly Lys288 (VI:26) and Trp304 (VII:03), areshown to create adverse steric interactions with all delta andkappa selective ligands examined, thereby disrupting their bindingmodes. These results are consistent with, and serve as an explanationfor, the observed pharmacology of this receptor, lending supportto both the validity of the `message–address' conceptitself and to the use of molecular modeling approaches in itsapplication.     

Mechanical Properties of Silicon Oxycarbide Ceramic Foams

The mechanical properties of ceramic foams obtained through a novel process that uses the direct foaming and pyrolysis of preceramic polymer/polyurethane solutions were investigated. The elastic modulus, flexural strength, and compressive strengths were obtained for foams in the as-pyrolyzed condition; values up to 7.1 GPa, 13 MPa, and 11 MPa, respectively, were obtained. The strength of the foam was virtually unchanged at temperatures up to 1200°C in air; however, long-term exposure at 1200°C led to a moderate degradation in strength, which was attributed to the evolution of intrastrut porosity during the oxidation of residual free carbon, as well as devitrification of the foams struts.     

Reaction of Aryl Iodides with (PCP)Pd(II)—Alkyl and Aryl Complexes: Mechanistic Aspects of Carbon—Carbon Bond Formation

The reaction of the PCP-type complex Pd(Me){2,6-(ⁱPr₂PCH₂)₂C₆H₃}( 3 ) with phenyl iodide results in the formation of Pd(I){2,6-(ⁱPr₂PCH₂)₂C₆H₃} ( 5 ), methyl iodide, toluene, and biphenyl. Formation of Pd(Ph){2,6-(ⁱPr₂PCH₂)₂C₆H₃}( 4 ) is observed during the reaction by ³¹P NMR. Reaction of 4 with aryl iodides results in the formation of 5 and Ph–Ph, Ph–Ar, and Ar–Ar, products indicative of a radical reaction. Under pseudo-first-order conditions, the rates of the reactions follow the order p-OMe > p-Me > H > p-NO₂ > m-Cl. The reaction is likely to involve electron transfer from 4 to the aryl iodide followed by fast decomposition of a postulated radical cation [Pd(Ph){2,6-(ⁱPr₂PCH₂)₂C₆H₃}]^+. ( 4 ^+.) to give a phenyl radical and [Pd{2,6-(ⁱPr₂PCH₂)₂C₆H₃}]⁺ ( 6 ⁺). Facile decomposition of the aryl iodide radical anion generates an aryl radical and I⁻. Recombination of aryl radicals gives rise to mixed biaryls, and 6 ⁺ combines with I⁻ to give 5 .     

Chelation of chitosan derivatives with zinc ions. II. Association complexes of Zn2+ onto O,N‐carboxymethyl chitosan

The chelation of zinc ions onto O,N‐carboxymethyl chitosan (ONCMCh) was characterized using a Fourier transform infrared (FTIR) spectrophotometer and a scanning electron microscope (SEM). From the FTIR spectra, little change in the absorption intensities and frequencies at 3300–3600 cm⁻¹ of Zn²⁺ ONCMCh chelated specimens suggested that  OH and  NH₂ groups were not participating in the chelation reaction. The absence of absorption bands at 1755–1700 cm⁻¹ suggested that the carboxyl group CO was not ionized, and the ionized CO bands were observed at 1400–1600 cm⁻¹ for chelated specimens. Thus, the chelation sites took place at the carboxyl group rather than at the  OH and NH₂ groups. It also confirmed that water‐insoluble chelates, which were formed through the Zn O and Zn N bonds, presented a tetrahedral structure. The water‐soluble complexes where zinc ions connected with oxygen of CO and water molecules were only due to electron attraction. Formation of different microstructures on the surfaces, as revealed by SEM, provided evidence to distinguish different chelating mechanisms between water‐soluble and water‐insoluble complexes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1476–1485, 2001     

Elastic Analysis of the Loop Tack Test for Pressure Sensitive Adhesives

The behavior of pressure sensitive adhesive (PSA) tapes is sometimes examined via the loop tack test, in which a loop of the tape is brought into contact with a flat surface and then pulled away. A numerical analysis of the test is presented here. The loop is treated as an elastica, but with a nonlinear moment-curvature relation, so that the material is assumed to be elastic and inextensible. Debonding at the edge of the contact region is assumed to occur when the adhesive reaches a critical elongation. This elongation is assumed to depend on the maximum contact pressure and, in part of the results, on the length of time of contact. Shapes of the loop and values of the corresponding forces are obtained using a shooting method, and the effects of the stiffness and thickness of the adhesive and backing are examined.     

Cellulose furoate. I. Synthesis in homogeneous and heterogeneous systems

Cellulose furoate was synthesized via heterogeneous and homogeneous reactions. Cotton cellulose and wood cellulose were used. Lithium chloride/dimethylacetamide solvent was used to dissolve the cellulose for the homogeneous reaction. The esterification reaction between cellulose and 2‐furoyl chloride was systematically studied. It revealed that the activation of cellulose was important for its esterification reaction. Activation by solvent exchange decreased the crystallinity and increased the accessibility of cellulose. X‐ray diffraction analysis showed no significant change in the spectrogram after activation of cellulose. The degree of substitution of cellulose furoate was influenced by the molecular weight of the cellulose, the stoichiometry of the reagents, the acid scavenger, and the reaction time. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2649–2655, 2001     

Polymerization of methyl methacrylate with a thermal iniferter: Diethyl 2,3‐dicyano‐2,3‐di(p‐tolyl)succinate

A hexa‐substituted ethane type compound, diethyl‐2,3‐dicyano‐2,3‐di(p‐tolyl)succinate (DCDTS), was successfully synthesized and used for initiation of methyl methacrylate (MMA) polymerization. The reaction demonstrated the characteristics of a “living” polymerization; i.e., both the yield and the molecular weight of the resulting polymers increased linearly with increasing reaction time, the molecular‐weight distribution of PMMA obtained was ～1.60 and almost unaffected by the conversion, and the resultant polymer can be chain extended by adding fresh MMA. End group analysis of the resultant PMMA confirmed that DCDTS behaves as a thermal iniferter for MMA polymerization. A block copolymer was prepared from the resultant PMMA, which contains a hexa‐substituted C? C bond functional end group. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2566–2572, 2001