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Background The mechanical properties of parenchyma cell walls and the strength and extension of adhesion areas between adjacent cells, jointly with cell turgor, are main determinants of firmness of fleshy fruits. These traits are modified during ripening leading to fruit softening. Cell wall modifications involve the depolymerisation of matrix glycans and pectins, the solubilisation of pectins and the loss of neutral sugars from pectin side chains. These changes weaken the cell walls and increase cell separation, which in combination with a reduction in cell turgor, bring about textural changes. Atomic force microscopy (AFM) has been used to characterise the nanostructure of cell wall polysaccharides during the ripening and postharvest storage of several fruits. This technique allows the imaging of individual polymers at high magnification with minimal sample preparation. Scope and approach This paper reviews the main features of the cell wall disassembly process associated to fruit softening from a nanostructural point of view, as has been provided by AFM studies. Key findings and conclusions AFM studies show that pectin size, ramification and complexity is reduced during fruit ripening and storage, and in most cases these changes correlate with softening. Postharvest treatments that improve fruit quality have been proven to preserve pectin structure, suggesting a clear link between softening and pectin metabolism. Nanostructural characterisation of cellulose and hemicellulose during ripening has been poorly explored by AFM and the scarce results available are not conclusive. Globally, AFM could be a powerful tool to gain insights about the bases of textural fruit quality in fresh and stored fruits.

The effects of Ca2+ (0–75 mg/g pectin) and sucrose (0–40%, w/w) or sweeteners (0.1, 0.05% of stevia or saccharin) and pH (3.0, 4.5, 6.8) on the rheological properties of gels formed with sunflower pectins purified by conventional method (Conv-pectin), microfiltration (MF-pectin) and ultrafiltration (UF-pectin) were investigated. The main objective was to develop alternative low-calorie pectin gels without altered gelation behaviour. Thus, the impact of stevia and saccharin on gel formation was studied maintaining the sweetness. All pectins formed gel only with Ca2+ at the maximum concentration (75 mg/g) being MF-pectin gel the firmest. Regardless type and concentration of sweeteners sucrose concentration, the strongest gels were obtained at pH 3.0 with UF-pectin. However, with the sweeteners, the strongest gels were made at pH 4.6 with Conv-pectin and MF-pectin without significant differences. These findings show, for the first time, the potential of stevia and saccharin in the elaboration of gels from sunflower pectin, suggesting the application of these low-calories and low-glycemic index gels in a wide range of foods., This work has been funded by MINECO of Spain, Project AGL2014-53445- R. N. Muñoz-Almagro thanks to Ministry of Economy of Spain for providing her FPI predoctoral fellowship. The authors also gratefully acknowledge the support of the Biotechnology and Biological Sciences Research Council (BBSRC) through the BBSRC Institute Strategic Programme Food Innovation and Health BB/R012512/1 and its constituent project BBS/E/F/000PR10345.

It is becoming increasingly clear that bacterial extracellular vesicles (BEVs) produced by members of the intestinal microbiota can contribute to microbe-host cell interactions that impact on host health. A major unresolved question is the nature of the cargo packaged into these BEVs and how they can impact on host cell function. Here we have analysed the proteome of BEVs produced by the major human gut symbiont Bacteroides thetaiotaomicron in both in vitro cultures using defined and complex medias, and in vivo in fed or fasted animals to determine the impact of nutrient stress on the BEV proteome, and to identify proteins specifically enriched in BEVs produced in vivo. In contrast to BEVs produced in vitro where limiting nutrient provision resulted in an increase in a large fraction of proteins, the protein content of BEVs extracted from fasted versus fed mice was less affected with similar numbers of proteins showing increased and decreased abundance. We identified 102 proteins exclusively enriched in BEVs in vivo of which the majority (66/102) were enriched independently of their expression in the parent cells implicating the existence of an active mechanism to drive the selection of a group of proteins for their secretion into BEVs within the intestine. Amongst these abundantly expressed proteins in BEVs in vivo were a bile salt hydrolase and a dipeptidyl peptidase IV that were characterised further and shown to be active and able to degrade host-derived substrates with defined roles in metabolism. Collectively these findings provide additional evidence for the role of BEVs in microbiota-host interactions with their contents playing key roles in the maintenance of intestinal homeostasis, and host metabolism.

Highlights • New AFM imaging methodology BlueDrive™ enabling resolution of xanthan’s helix. • Visual evidence of the structural composition of xanthan’s helices. • Confirmation of the effect of counterion screening on structural ordering., Direct visual evidence obtained by atomic force microscopy demonstrates that when xanthan is adsorbed from aqueous solution onto the heterogeneously charged substrate mica, its helical conformation is distorted. Following adsorption it requires annealing for several hours to restore its ordered helical state. Once the helix state reforms, the AFM images obtained showed clear resolution of the periodicity with a value of 4.7 nm consistent with the previously predicted models. In addition, the images also reveal evidence that the helix is formed by a double strand, a clarification of an ambiguity of the xanthan ultrastructure that has been outstanding for many years.

Truly original Austrian contributions to the theory of entrepreneurship began with Ludwig von Mises’ 1940 Nationalokonomie. This chapter presents the new subjectivist theory of entrepreneurship in summary form. It discusses and assesses J. A. Schumpeter’s theory and strongly argues that view and aims to maintain that it threatens to undermine Mises’ most important contribution to economic theory. The ‘function’ of entrepreneurship embodies all that can be deduced about how time and uncertainty are relevant to the choices to identify and use factors of production to satisfy consumers’ wants. The chapter argues that the highest point in our understanding of entrepreneurship was achieved when entrepreneurship came to be associated with the distinctly human part of human action in the market economy. It focuses mainly on I. M. Kirzner’s idea of entrepreneurship as alertness. Alertness leads individuals to make discoveries of information that is valuable in the satisfaction of wants.

Nanofibrils of β-lactoglobulin can be assembled into bundles by site-specific noncovalent cross-linking with high-methoxyl pectin (Hettiarachchi et al. Soft Matter 2016, 12, 756). Here we characterized the nanomechanical properties of bundles using atomic force microscopy and force spectroscopy. Bundles had Gaussian cross sections and a mean height of 17.4 ± 1.4 nm. Persistence lengths were calculated using image analysis with the mean-squared end-to-end model. The relationship between the persistence length and the thickness had exponents of 1.69-2.30, which is consistent with previous reports for other fibril types. In force spectroscopy experiments, the bundles stretched in a qualitatively different manner to fibrils, and some of the force curves were consistent with peeling fibrils away from bundles. The flexibility of pectin-linked nanofibril bundles is likely to be tunable by modulating the stiffness and length of fibrils and the ratio of pectin to fibrils, giving rise to a wide range of structures and functionalities.

This article describes the progress in the development of the atomic force microscope as an imaging tool and a force transducer, with particular reference to applications in food science. Use as an imaging tool has matured and emphasis is placed on the novel insights gained from the use of the technique to study food macromolecules and food colloids, and the subsequent applications of this new knowledge in food science. Use as a force transducer is still emerging and greater emphasis is given on the methodology and analysis. Where available, applications of force measurements between molecules or between larger colloidal particles are discussed, where they have led to new insights or solved problems related to food science. The future prospects of the technique in imaging or through force measurements are discussed., Graphical abstract Image, Highlights • Ultrastructure of polysaccharides. • Structure-function relations of food molecules. • Physical effects of interfacial stabilisers and deformable colloids. • Bio and physical activity of pectin components. • Characterisation of glycan distribution on mucin.

Significance Gut bacteria play a key role in health and disease, but the molecular mechanisms underpinning their interaction with the host remain elusive. The serine-rich repeat proteins (SRRPs) are a family of adhesins identified in many Gram-positive pathogenic bacteria. We previously showed that beneficial bacterial species found in the gut also express SRRPs and that SRRP was required for the ability of Lactobacillus reuteri strain to colonize mice. Here, our structural and biochemical data reveal that L. reuteri SRRP adopts a β-solenoid fold not observed in other structurally characterized SRRPs and functions as an adhesin via a pH-dependent mechanism, providing structural insights into the role of these adhesins in biofilm formation of gut symbionts., Lactobacillus reuteri, a Gram-positive bacterial species inhabiting the gastrointestinal tract of vertebrates, displays remarkable host adaptation. Previous mutational analyses of rodent strain L. reuteri 100-23C identified a gene encoding a predicted surface-exposed serine-rich repeat protein (SRRP100-23) that was vital for L. reuteri biofilm formation in mice. SRRPs have emerged as an important group of surface proteins on many pathogens, but no structural information is available in commensal bacteria. Here we report the 2.00-Å and 1.92-Å crystal structures of the binding regions (BRs) of SRRP100-23 and SRRP53608 from L. reuteri ATCC 53608, revealing a unique β-solenoid fold in this important adhesin family. SRRP53608-BR bound to host epithelial cells and DNA at neutral pH and recognized polygalacturonic acid (PGA), rhamnogalacturonan I, or chondroitin sulfate A at acidic pH. Mutagenesis confirmed the role of the BR putative binding site in the interaction of SRRP53608-BR with PGA. Long molecular dynamics simulations showed that SRRP53608-BR undergoes a pH-dependent conformational change. Together, these findings provide mechanistic insights into the role of SRRPs in host–microbe interactions and open avenues of research into the use of biofilm-forming probiotics against clinically important pathogens.

There is great interest in understanding changes that occur to cell wall constituents during saccharification of pretreated lignocellulose, particularly in relation to recalcitrance of the residues. This paper reports the effects of hydrothermal pretreatment followed by enzyme hydrolysis on the extractability and properties of recalcitrant wheat straw polymers. The results show that the undigested residue had lost much of its archestructure. Compositional analysis portrayed a considerable loss of cross-linking di-ferulic acid phenolics, hemicellulosic and cellulosic sugars. The remaining cellulosic and non-cellulosic polysaccharides were much more readily extractable in alkali and molecular profiling revealed the presence of low Mw oligomers in the fractions suggesting the partial enzyme hydrolysis of hemicelluloses and cellulose. Simultaneous saccharification and fermentation of the pretreated and enzyme-digested residues surprisingly resulted in ethanol yields of up to 99% of the theoretical. This is discussed in relation to the “recalcitrant” nature of the original pretreated and enzyme digested biomass.

Atomic force microscopy (AFM) is a high resolution technique for studying the external and internal structures of starch granules. For this purpose granules were isolated from bananas and embedded in a non-penetrating resin. To achieve image contrast of the ultrastructure, the face of the cut blocks were wetted in steam and force modulation mode imaging was used. Images of starch from green bananas showed large variation of height across the granule due to a locational specific absorption of water and swelling of amorphous regions; the data reveal that the center of the granules are structurally different and have different viscoelastic properties. Images of starches from ripe bananas showed an even greater different level of organization: absence of growth rings around the hilum; the central region of the granule is richer in amylose; very porous surface with round shaped dark structures; the size of blocklets are larger than the green fruits.

WOS: 000358225100082 PubMed ID: 26139522 We report the discovery and characterization of a double-stranded RNA (dsRNA) mycovirus isolated from the human pathogenic fungus Aspergillus fumigatus, Aspergillus fumigatus tetramycovirus-1 (AfuTmV-1), which reveals several unique features not found previously in positive-strand RNA viruses, including the fact that it represents the first dsRNA (to our knowledge) that is not only infectious as a purified entity but also as a naked dsRNA. The AfuTmV-1 genome consists of four capped dsRNAs, the largest of which encodes an RNA-dependent RNA polymerase (RdRP) containing a unique GDNQ motif normally characteristic of negative-strand RNA viruses. The third largest dsRNA encodes an S-adenosyl methionine-dependent methyltransferase capping enzyme and the smallest dsRNA a P-A-S-rich protein that apparently coats but does not encapsidate the viral genome as visualized by atomic force microscopy. A combination of a capping enzyme with a picorna-like RdRP in the AfuTmV-1 genome is a striking case of chimerism and the first example (to our knowledge) of such a phenomenon. AfuTmV-1 appears to be intermediate between dsRNA and positive-strand ssRNA viruses, as well as between encapsidated and capsidless RNA viruses. Thai Government education program; Turkish Government education program; Leverhulme TrustLeverhulme Trust; Erasmus European Union Programme We thank Ren Zhang (Commonwealth Scientific and Industrial Research Organisation) and Matt Dickinson (University of Nottingham) for sequence data of flax rust Melampsora lini dsRNAs, and Profs. Eugene Koonin and Valerian Dolja for their advice on phylogenetic analyses. L.K. and S.O. thank the Thai and the Turkish Government education programs, respectively, for supporting their PhD programs. R.H.A.C. thanks The Leverhulme Trust for an Emeritus Fellowship award, and I.K.-L. acknowledges the support of the Erasmus European Union Programme.

Intestinal crypt fission is a homeostatic phenomenon, observable in healthy adult mucosa, but which also plays a pathological role as the main mode of growth of some intestinal polyps. Building on our previous individual based model for the small intestinal crypt and on in vitro cultured intestinal organoids, we here model crypt fission as a budding process based on fluid mechanics at the individual cell level and extrapolated predictions for growth of the intestinal epithelium. Budding was always observed in regions of organoids with abundant Paneth cells. Our data support a model in which buds are biomechanically initiated by single stem cells surrounded by Paneth cells which exhibit greater resistance to viscoelastic deformation, a hypothesis supported by atomic force measurements of single cells. Time intervals between consecutive budding events, as simulated by the model and observed in vitro, were 2.84 and 2.62 days, respectively. Predicted cell dynamics was unaffected within the original crypt which retained its full capability of providing cells to the epithelium throughout fission. Mitotic pressure in simulated primary crypts forced upward migration of buds, which simultaneously grew into new protruding crypts at a rate equal to 1.03 days-1 in simulations and 0.99 days-1 in cultured organoids. Simulated crypts reached their final size in 4.6 days, and required 40 6.2 days to migrate to the top of the primary crypt. The growth of the secondary crypt is independent of its migration along the original crypt. Assuming unrestricted crypt fission and multiple budding events, a maximal growth rate of the intestinal epithelium of 0.10 days-1 43 is predicted and thus approximately 22 days are required for a 10-fold increase of polyp size. These predictions are in agreement with the time reported to develop macroscopic adenomas in mice after loss of Apc in intestinal stem cells.

Strawberry ( Fragaria × anannasa Duch.) is one of the most important soft fruit. Rapid loss of firmness occurs during the ripening process, resulting in a short shelf life and high economic losses. To get insight into the role of pectin matrix in the softening process, cell walls from strawberry fruit at two developmental stages, unripe-green and ripe-red, were extracted and sequentially fractionated with different solvents to obtain fractions enriched in a specific component. The yield of cell wall material as well as the per fresh weight contents of the different fractions decreased in ripe fruit. The largest reduction was observed in the pectic fractions extracted with a chelating agent (trans-1,2- diaminocyclohexane-N,N,N’N’-tetraacetic acid, CDTA fraction) and those covalently bound to the wall (extracted with Na 2 CO 3 ). Uronic acid content of these two fractions also decreased significantly during ripening, but the amount of soluble pectins extracted with phenol:acetic acid:water (PAW) and water increased in ripe fruit. Fourier transform infrared spectroscopy of the different fractions showed that the degree of esterification decreased in CDTA pectins but increased in soluble fractions at ripen stage. The chromatographic analysis of pectin fractions by gel filtration revealed that CDTA, water and, mainly PAW polyuronides were depolymerised in ripe fruit. By contrast, the size of Na 2 CO 3 pectins was not modified. The nanostructural characteristics of CDTA and Na 2 CO 3 pectins were analysed by atomic force microscopy (AFM). Isolated pectic chains present in the CDTA fractions were significantly longer and more branched in samples from green fruit than those from red fruit. No differences in contour length were observed in Na 2 CO 3 strands between samples of both stages. However, the percentage of branched chains decreased from 19.7% in unripe samples to 3.4% in ripe fruit. The number of pectin aggregates was higher in green fruit samples of both fractions. These results show that the nanostructural complexity of pectins present in CDTA and Na 2 CO 3 fractions diminishes during fruit development, and this correlates with the solubilisation of pectins and the softening of the fruit.

In this article, edible hydrocolloid films were prepared by using Citrus pectins and the protein phaseolin in the presence of microbial transglutaminase, an enzyme able to catalyze isopeptide bonds between endo-protein-reactive glutamine and lysine residues. For the first time, trehalose, a nonreducing homodisaccharide into which two glucose units are linked together by a α-1,1-glycosidic linkage, was used as a component of hydrocolloid films constituted of both proteins and carbohydrates. Our data have demonstrated that these films act as very effective barriers to gases, especially to CO2 . They also present a high antioxidant capability as measured by the 2,2-diphenyl-1-picrylhydrazyl scavenging assay. In addition, the films were characterized using Atomic Force Microscopy, a powerful tool used to evaluate film surface topography and roughness. The results of our experiments clearly indicate that the trehalose-containing films prepared both in the presence and absence of transglutaminase are composed of nanoparticles with a smooth surface, having similar roughness values (Rα). In conclusion, according to barrier and antioxidant properties and to their structure, it is possible to consider the trehalose-containing films as innovative bioplastics potentially able to protect different kinds of foods.

Summary The mucus layer covering the gastrointestinal (GI) epithelium is critical in selecting and maintaining homeostatic interactions with our gut bacteria. However, the underpinning mechanisms of these interactions are not understood. Here, we provide structural and functional insights into the canonical mucus-binding protein (MUB), a multi-repeat cell-surface adhesin found in Lactobacillus inhabitants of the GI tract. X-ray crystallography together with small-angle X-ray scattering demonstrated a ‘beads on a string’ arrangement of repeats, generating 174 nm long protein fibrils, as shown by atomic force microscopy. Each repeat consists of tandemly arranged Ig- and mucin-binding protein (MucBP) modules. The binding of full-length MUB was confined to mucus via multiple interactions involving terminal sialylated mucin glycans. While individual MUB domains showed structural similarity to fimbrial proteins from Gram-positive pathogens, the particular organization of MUB provides a structural explanation for the mechanisms in which lactobacilli have adapted to their host niche by maximizing interactions with the mucus receptors, potentiating the retention of bacteria within the mucus layer. Together, this study reveals functional and structural features which may affect tropism of microbes across mucus and along the GI tract, providing unique insights into the mechanisms adopted by commensals and probiotics to adapt to the mucosal environment.

The insoluble glucan polymer starch is a major player in the human diet; it is also an important bulk commodity. Nonetheless, our understanding of its biochemistry remains poor, not least because of the challenge of analysing enzymes that operate across the solid–liquid interface. In the present study, the enzymatic polymerisation of glucans immobilised on gold sensor chip and nanoparticle surfaces was achieved with Arabidopsis phosphorylase AtPHS2. The basis of the action of AtPHS2 on surface glucans could be rationalised through consideration of the X-ray crystal structure of this enzyme, which identified a previously unreported enzyme surface binding site for glucans. Extension of the glucan-coated sensor chip surfaces could be monitored in real time by SPR, enabling kinetic analysis of AtPHS2-mediated glucan synthesis, which showed similar efficiency to in solution analyses. Extension of both sensor and nanoparticles surfaces coated with glucan was analysed by TEM, which confirmed glucan polymerisation. The arrangement of newly formed glucan chains into ordered helical arrangements was evident from iodine staining, as well as from enzyme response characteristics that proved typical of starch-like material. As such, the glucan-modified sensor chip and nanoparticle surfaces represent novel tools with which to analyse starch-active enzymes.

Mucins are the main components of the gastrointestinal mucus layer. Mucin glycosylation is critical to most intermolecular and intercellular interactions. However, due to the highly complex and heterogeneous mucin glycan structures, the encoded biological information remains largely encrypted. Here we have developed a methodology based on force spectroscopy to identify biologically accessible glycoepitopes in purified porcine gastric mucin (pPGM) and purified porcine jejunal mucin (pPJM). The binding specificity of lectins Ricinus communis agglutinin I (RCA), peanut (Arachis hypogaea) agglutinin (PNA), Maackia amurensis lectin II (MALII), and Ulex europaeus agglutinin I (UEA) was utilized in force spectroscopy measurements to quantify the affinity and spatial distribution of their cognate sugars at the molecular scale. Binding energy of 4, 1.6, and 26 aJ was determined on pPGM for RCA, PNA, and UEA. Binding was abolished by competition with free ligands, demonstrating the validity of the affinity data. The distributions of the nearest binding site separations estimated the number of binding sites in a 200-nm mucin segment to be 4 for RCA, PNA, and UEA, and 1.8 for MALII. Binding site separations were affected by partial defucosylation of pPGM. Furthermore, we showed that this new approach can resolve differences between gastric and jejunum mucins.—Gunning, A. P., Kirby, A. R., Fuell, C., Pin, C., Tailford L. E., Juge, N. Mining the “glycocode”—exploring the spatial distribution of glycans in gastrointestinal mucin using force spectroscopy.

Pectins analysed by AFM are visualized as individual chains, branched or unbranched, and aggregates. To investigate the nature of these structures, sodium carbonate soluble pectins from strawberry fruits were digested with endo-polygalacturonase M2 from Aspergillus aculeatus and visualized by AFM. A gradual decrease in the length of chains was observed as result of the treatment, reaching a minimum LN value of 22nm. The branches were not visible after 2h of enzymatic incubation. The size of complexes also diminished significantly with the enzymatic digestion. A treatment to hydrolyse rhamnogalacturonan II borate diester bonds neither affected chains length or branching nor complex size but reduced the density of aggregates. These results suggest that chains are formed by a mixture of homogalacturonan and more complex molecules composed by a homogalacturonan unit linked to an endo-PG resistant unit. Homogalacturonan is a structural component of the complexes and rhamnogalacturonan II could be involved in their formation.

The structure and conformation of xanthan in aqueous solution following various processing treatments typically encountered in its application were investigated in this study. Treatments such as heating, autoclaving, high pressure homogenisation and irradiation were subjected to the same sample. Parameters such as weight average molecular weight (M-w). polydispersity index, root mean square radius of gyration, intrinsic viscosity and Huggins constant were used to monitor the effect of these treatments. Additionally, we have quantified the mass recovery of samples examined by gel permeation chromatography and light scattering to properly account for all fractions present in xanthan solutions. Atomic force microscopy (AFM) images together with height measurements confirmed that xanthan conformation is double helical ordered renatured state (pre-heat treated by the manufacturer) in dilute solution conditions and random coil conformation in very dilute solution. The ordered (renatured) conformation is shown to have partially molten double helix, with more flexibility than the perfectly ordered native double helix. Heat treatment for 2h at 85 degrees C reduces the M-w of xanthan to half its initial value, and mass recovery measurements indicate that it completely overcomes its associative nature. Thermally treated xanthan solution in the dilute region leads to an order-disorder transition, as determined by contour length per unit mass. Similarly, irradiation of xanthan solution results in an order-disorder transition together with the production of single strand low molecular weight molecules. Autoclaving and high pressure homogenisation treatments cause degradation of xanthan. The results from treated xanthan solutions following high pressure homogenisation and irradiation confirm that xanthan does not reassociate. A revised summary of xanthan conformation in solution together with schematic models following the various treatments are proposed. (C) 2012 Elsevier Ltd. All rights reserved.

This study describes the adsorption behavior of mixed protein/surfactant systems at the air-water interface: specifically fibrinogen and the fluorinated and hydrogenated surfactants (C(8)FONa, C(8)HONa, and C(12)HONa). Surface tension techniques and atomic force microscopy (AFM) have been combined to investigate the adsorption behavior of these mixed systems. Interfacial rheology showed that fibrinogen has a low dilatational modulus at the air-water interface when compared to other proteins, suggesting the formation of a weak surface network. Fluorinated and hydrogenated surfactants severely decreased the dilatational modulus of the adsorbed fibrinogen film at the air-water interface. These measurements suggest the progressive displacement of fibrinogen from the air-water interface by both types of surfactants. However, in the case of fibrinogen/fluorinated surfactant systems, surface tension and dilatational rheology measurements suggest the formation of complexes with improved surface activity. AFM imaging of fibrinogen in the presence and absence of surfactants provided new information on the structure of mixed surface films, and revealed new features of the interaction of fibrinogen with hydrogenated and fluorinated surfactants. These studies suggest complexes formed between fibrinogen and fluorinated surfactants which are more surface active than fibrinogen, while the absence of interaction between fibrinogen and hydrogenated surfactants (C(8)HONa and C(12)HONa) results in compaction of the surface layer.

Pectin is an integral component of non-graminaceous plant cell walls. It is believed to form an interconnected network structure independent of the cellulose-xyloglucan network structure. Pectin gels are often used as a model for the pectin network structure within the plant cell wall. Atomic force microscopy studies of calcium-induced gel precursors, and fragments released from gels, suggest that association leads to a branched fibrous structure within the gels. Enzymatic de-esterification of high-methoxyl pectin in the presence of calcium ions can induce gelation of the pectin. Thus pectin gel networks may provide a model for a self-assembled network structure within the middle lamella region of the plant cell wall. The pectin network in plant cell walls is a source of soluble and insoluble fibre. In addition to the health benefits associated with the dietary fibre aspects of pectin new health claims are emerging. Recently published in vitro and in vivo animal studies, and human studies, suggest that oral consumption of a modified form of pectin may have anti-cancer properties. These studies suggest that the modified pectin may act on a range of cancers at several stages of progression of the cancer. It has been hypothesised that this generic action is due to the modification allowing release of bioactive fragment(s) which are claimed to bind specifically to and inhibit the action of the mammalian lectin galectin 3 (Gal3). Gal3 is a key regulator of cellular homeostasis and plays important roles in several stages of cancer metastasis. Studies using force spectroscopy, flow cytometry and fluorescence microscopy suggest that the bioactive fragments of pectin may be pectin-derived galactans.

Temperature-dependent formation of gelatin−poly(galacturonic acid) (PGA) multilayer films based on the layer-by-layer approach and their stability to changes in temperature, pH, and NaCl concentrat...

Overexpression of the lactococcal CsiA protein affects the cell wall integrity of growing cells and leads to leakage of intracellular material. This property was optimized and exploited for the targeted release of biologically active compounds into the extracellular environment, thereby providing a new delivery system for bacterial proteins and peptides. The effects of different levels of CsiA expression on the leakage of endogenous lactate dehydrogenase and nucleic acids were measured and related to the impact of CsiA expression on Lactococcus lactis cell viability and growth. A leakage phenotype was obtained from cells expressing both recombinant and nonrecombinant forms of CsiA. As proof of principle, we demonstrated that CsiA promotes the efficient release of the heterologous Listeria bacteriophage endolysin LM4 in its active form. Under optimized conditions, native and heterologous active-molecule release is possible without affecting cell viability. The ability of CsiA to release intracellular material by controlled lysis without the requirement for an external lytic agent provides a technology for the control of both the extent of lysis and its timing. Taken together, these results demonstrate the potential of this novel approach for applications including product recovery in industrial fermentations, food processing, and medical therapy.

It is increasingly recognized that changes in the composition of the oil-water interface can markedly affect pancreatic lipase adsorption and function. To understand interfacial mechanisms determining lipase activity, we investigated the adsorption behavior of bile salts and pancreatic colipase and lipase onto digalactosyldiacylglycerol (DGDG) and dipalmitoylphosphatidylcholine (DPPC) monolayers at the air-water interface. The results from Langmuir trough and pendant drop experiments showed that a DGDG interface was more resistant to the adsorption of bile salts, colipase, and lipase compared to that of DPPC. Atomic force microscopy (AFM) images showed that the adsorption of bile salts into a DPPC monolayer decreased the size of the liquid condensed (LC) domains while there was no visible topographical change for DGDG systems. The results also showed that colipase and lipase adsorbed exclusively onto the mixed DPPC-bile salt regions and not the DPPC condensed phase. When the colipase and lipase were in excess, they fully covered the mixed DPPC-bile salt regions. However, the colipase and lipase coverage on the mixed DGDG-bile salt monolayer was incomplete and discontinuous. It was postulated that bile salts adsorbed into the DPPC monolayers filling the gaps between the lipid headgroups and spacing out the lipid molecules, making the lipid hydrocarbon tails more exposed to the surface. This created hydrophobic patches suitable for the binding of colipase and lipase. In contrast, bile salts adsorbed less easily into the DGDG monolayer because DGDG has a larger headgroup, which has strong intermolecular interactions and the ability to adopt different orientations at the interface. Thus, there are fewer hydrophobic patches that are of sufficient size to accommodate the colipase on the mixed DGDG-bile salt monolayer compared to the mixed DPPC-bile salt regions. The results from this work have reinforced the hypothesis that the interfacial molecular packing of lipids at the oil-water interface influences the adsorption of bile salts, colipase, and lipase, which in turn impacts the rate of lipolysis.

It has been reported that modified forms of pectin possess anticancer activity. To account for this bioactivity, it has been proposed that fragments of pectin molecules can act by binding to and inhibiting the various roles of the mammalian protein galectin 3 (Gal3) in cancer progression and metastasis. Despite this clear molecular hypothesis and evidence for the bioactivity of modified pectin, the structural origins of the "bioactive fragments" of pectin molecules are currently ill defined. By using a combination of fluorescence microscopy, flow cytometry, and force spectroscopy, it has been possible to demonstrate, for the first time, specific binding of a pectin galactan to the recombinant form of human Gal3. Present studies suggest that bioactivity resides in the neutral sugar side chains of pectin polysaccharides and that these components could be isolated and modified to optimize bioactivity.

The competitive displacement of a model protein (beta-lactoglobulin) by bile salts from air-water and oil-water interfaces is investigated in vitro under model duodenal digestion conditions. The aim is to understand this process so that interfaces can be designed to control lipid digestion thus improving the nutritional impact of foods. Duodenal digestion has been simulated using a simplified biological system and the protein displacement process monitored by interfacial measurements and atomic force microscopy (AFM). First, the properties of beta-lactoglobulin adsorbed layers at the air-water and the olive oil-water interfaces were analyzed by interfacial tension techniques under physiological conditions (pH 7, 0.15 M NaCl, 10 mM CaCl2, 37 degrees C). The protein film had a lower dilatational modulus (hence formed a weaker network) at the olive oil-water interface compared to the air-water interface. Addition of bile salt (BS) severely decreased the dilatational modulus of the adsorbed beta-lactoglobulin film at both the air-water and olive oil-water interfaces. The data suggest that the bile salts penetrate into, weaken, and break up the interfacial beta-lactoglobulin networks. AFM images of the displacement of spread beta-lactoglobulin at the air-water and the olive oil-water interfaces suggest that displacement occurs via an orogenic mechanism and that the bile salts can almost completely displace the intact protein network under duodenal conditions. Although the bile salts are ionic, the ionic strength is sufficiently high to screen the charge allowing surfactant domain nucleation and growth to occur resulting in displacement. The morphology of the protein networks during displacement is different from those found when conventional surfactants were used, suggesting that the molecular structure of the surfactant is important for the displacement process. The studies also suggest that the nature of the oil phase is important in controlling protein unfolding and interaction at the interface. This in turn affects the strength of the protein network and the ability to resist displacement by surfactants.

Specific molecular-receptor interactions with gut epithelium cells are important in understanding bioactivity of food components and drugs, binding of commensal microflora, attachment and initiation of defense mechanisms against pathogenic bacteria and for development of targeted delivery systems to the gut. However, methods for probing such interactions are lacking. Methodology has been developed and validated to measure specific molecular-receptor interactions on living human colorectal cancer cells as in vitro models for the gut epithelium. Atomic force microscopy (AFM) was used to measure ligand-receptor interactions and to map receptor locations on cell surfaces. Measurements were made using silica beads attached to the AFM tip-cantilever assembly, which were functionalized by coupling of ligands to the bead surface. Wheat germ agglutinin (WGA) binds to the glycosylated extracellular domain III of the epidermal growth factor receptor. Methodology was tested by measuring binding of WGA to the surface of confluent monolayers of living Caco-2 human intestinal epithelial cells. The measured modal detachment force of 125 pN is typical of values expected for single molecule interactions. Adhesive events were used to map the location of binding sites on the cell surface revealing heterogeneity in their distribution within and between cells within the monolayer.

In a recent paper, Guido Hulsmann (2002) advances the revolutionary idea that Austrian economists ought to base their concept of originary interest on the spread between the value of an end and the value of the means used to achieve the end. He points out that this idea stands in opposition to Ludwig von Mises’s argument that the concept should be based on the assumption of time preference, as presented in Human Action (1966). He also argues that whereas his idea enables one to link originary interest, as he defines it, to market interest, Mises’s idea does not. Hulsmann uses most of his paper to articulate his new idea. The first part of his paper, however, is largely a critique of Mises’s theory. The critique reaches particularly damning conclusions. He argues that Mises’s claim of the universality of time preference is flawed and that his concept of originary interest is based on an assumption about physical productivity. In addition, he argues that Mises’s concept of originary interest based on time preference does not allow one to deduce that entrepreneurial competition will result in a positive rate of interest in the market economy. The goal of this comment is to demonstrate that Hulsmann’s criticism of Mises is based on a series of misinterpretations and omissions. I demonstrate, by referring to the Misesian text, that time preference is a praxeological category (part 1) and that Mises’s concept of originary interest is not based on an assumption about physical productivity (part 2). I next show that regardless of whether Hulsmann is correct about Mises’s concepts of time preference and originary interest, the issue is not related to the central problem with which he is concerned—the derivation of market interest (also in part 1). Finally, I demonstrate that, contrary to Hulsmann, Mises did indeed show how entrepreneurial competition leads time preference and originary interest, which are present in all decisions to consume (sooner or later), to become a component of the market rate of interest (and therefore that originary interest in the market economy is positive). Part 3 discusses: (a) the deduction of positive market interest from the assumption of time preference and originary interest in individual action and (b) the disengagement of originary interest in the market economy from

In a seminal paper in neo-Austrian economics, Murray Rothbard criticized Mises. We analyze Rothbard's argument partly as a means of elucidating Mises's views and argue that Rothbard misinterpreted Mises and quoted him out of context. Rothbard failed to adequately support his claim that Mises held the beliefs that Rothbard attributed to him. Moreover, Rothbard's paper undermined the value freedom that Mises regarded as a crucial characteristic of economics. I Introduction LUDWIG VON MISES MAINTAINED THAT PRAXEOLOGY (the logic of human action) and economics (the logic of action applied to particular circumstances) are value free. He went on to argue that sound, value-free economic reasoning leads one to favor laissez faire. This paper presents the reasoning that enabled him to reach this apparently paradoxical conclusion. To my knowledge the reasoning is unique to Mises. One of Mises's staunchest defenders and "champions," Murray Rothbard, (1) criticized Mises on this issue. An examination of Mises's and Rothbard's arguments will show that Rothbard did not understand Mises's approach to the problem, apparently because he failed to consider the key passages on this issue in Human Action and because he misinterpreted the passages he did consider. Mises's argument that an economist could advocate laissez faire and still remain value free stemmed from his conception of the goal of economics. In his view, the goal is to debunk false views about how people in a society can achieve their non ascetic ends. To do this, economics must elucidate the nature of human cooperation under laissez faire by means of the division of labor under the conditions of private property. Then it must compare this with the means people would use to achieve such ends under the alternatives of socialism and interventionism. The economist could advocate laissez faire because economic reasoning shows that it enables people in a society to achieve their nonascetic ends to a greater extent than the alternatives. As long as the economist pursues the goal of comparing the systems with respect to their capacity to achieve these ends, and as long as his or her comparison employs the logic of praxeology, the economist need not worry about making value judgments. Mises's argument is presented in Section II of this paper. Section III presents Rothbard's view that value-free economics is a tool of ethics. Section IV describes and evaluates Rothbard's critique of Mises, showing how Rothbard misunderstood Mises's position and misinterpreted his arguments. Section V tries to explain Rothbard's misinterpretation by suggesting that his thought was unduly influenced by his acceptance of the welfare economics of his day. Section VI presents a brief conclusion. II Mises on Laissez Faire and Value-Free Economics TO UNDERSTAND MISES'S VIEWS ON LAISSEZ FAIRE, it is sufficient to read the passages referred to in the index of Human Action ([1949] 1966). In most places, he refers to it as an ideology of the old liberal economists. This ideology, in his view, helped to eliminate the restrictions of medieval times, facilitating the emergence of a private property system and free enterprise. He writes that "laissez faire philosophy had opened the way for capitalism by utterly destroying the fallacies of restrictionism" ([1949] 1966: 840). Similarly, "[t]he laissez faire ideology and its offshoot, the 'Industrial Revolution,' blasted the ideological and institutional barriers to progress and welfare" ([1949] 1966: 620). Note that in this last statement, Mises refers to laissez faire as an "ideology" and that he speaks of "progress." A brief discussion of these ideas will help clarify his argument. In Human Action, Mises defines ideology in relation to what he calls a world view: A world view is an interpretation of all things, and as a precept for action, an opinion concerning the best means for removing uneasiness as much as possible. …

I Introduction MISES ERRED TWICE IN THINKING that he had provided a defense of laissez faire based on value-free economics. First, when he discussed a market intervention, he did not realize that his defense made the unwarranted assumption that he knew the preferences of those who are affected by it. Second, partly because he made this unwarranted assumption, he failed to see that his defense was based on the unanimity principle and/or "his utilitarianism." These are the major deficiencies identified by Murray Rothbard in his 1976 paper. To the contrary, I have argued that Rothbard failed in that paper to comprehend the true basis of Mises's defense of laissez faire and that he attributed ideas to Mises, including the unanimity principle and utilitarianism, that he did not hold (Gunning 2005). A careful reading of my paper shows that I made two claims about Rothbard. First, Rothbard failed to identify Mises's principal argument for laissez faire. Mises's argument was based on a comparison, using value-free economic reasoning, of arguments for market intervention according to criteria that Mises claimed were either explicitly or implicitly espoused by those who promoted the intervention. Second, Rothbard misinterpreted Mises's analyses of the arguments against the particular interventionist policies that he cited in Mises's work. In his comment on my paper, Walter Block chose to criticize my second claim, basically arguing that I did not appreciate Rothbard's depth (Block 2005). His argument amounts to an effort to reaffirm Rothbard's critique of Mises's alleged error and Mises's alleged utilitarianism. In Section II of this reply, I provide the textual support for my first claim, which Block writes was absent from my original paper. In Sections III and IV, I focus on what I take to be the main assertions of both Rothbard and Block, as described in the introductory sentences above. In Section III, I argue that Mises did not believe or assume that he could know others' ends and, therefore, did not err in this respect. In Section IV, I argue that the assertion that Mises was a utilitarian contradicts what Mises himself wrote about the issue. In Section V, I respond to several minor points in Block's critique. II Mises's Defense of Laissez Faire as an Ideology Against the Ideologies of Socialism and Interventionism IN MY PAPER, I WROTE: "Mises's argument that an economist could advocate laissez faire and still remain value free stemmed from his conception of the goal of economics." What was that goal? Consider the following quotations from Mises's Human Action: It is the task of history to describe the historical conditions which made such a crude doctrine popular. Economics has another task. It must analyze both Marxian polylogism and the other brands of polylogism formed after its pattern, and expose their fallacies and contradictions. (Mises [1949] 1966: 75) It is the task of scientific technology and therapeutics to explode errors in their respective fields. It is the task of economics to expose erroneous doctrines in the field of social action. But if men do not follow the advice of science, but cling to fallacious prejudices, these errors are reality and must be dealt with as such. ([1949] 1966: 93) The main objective of praxeology and economics is to substitute consistent correct ideologies for the contradictory tenets of popular eclecticism. ([1949] 1966: 185) I regard these quotes as additional support for my proposition that, for Mises, the goal of economics is to show either that particular ideologies are contradictory or erroneous or that the policies promoted by those who hold the ideologies will not accomplish the aims that they believe the policies will accomplish. The goal, or set of goals, of economics can be accomplished with logical reasoning and judgments of relevance. …

Atomic force microscopy has been used to investigate the complexes formed between high molecular weight amylose chains and Aspergillus niger glucoamylase mutants (E400Q and W52F), wild-type A. niger starch binding domains (SBDs), and mutant SBDs (W563K and W590K) lacking either of the two starch binding sites. The images are interpreted in terms of a favourable binding between the amylose chains and the wild-type SBDs, leading to the formation of ring-like structures, in which parallel strands of the amylose molecule bind to both binding sites on the SBDs. The SBDs are seen to form a template for the assembly of an expanded amylosic double helix. This model for amylose-SBD binding has been used to propose a molecular mechanism for the role of the SBD in the hydrolytic action of glucoamylase on starch granules. The SBDs are considered to recognise the ends of amylosic double helices formed by the short amylosic chains present as branches on the amylopectin molecules, and displayed on the face of crystalline lamellae. This allows the binding and immobilisation of chain ends by the SBD, facilitating binding and cleavage by the exo-acting catalytic domain.

Surfactants, in particular nonionic surfactants, form phase-separated domains when competitively displacing protein films from a fluid interface. The present article seeks to quantify the size, shape, and number of the growing domains as the displacement progresses. The two proteins used in this study, β-casein and β-lactoglobulin, were separately displaced by the nonionic surfactant Tween 20. In the cases of both proteins, the mean surfactant domain area was found to increase exponentially as a function of the fraction (area) of the interface containing surfactant. Similarly, the number of domains per unit area was found to decrease rapidly for both proteins as a function of the surfactant area fraction. While computer simulations of domain growth could not closely mimic either of these traits, they suggested that a likely explanation for this is that the rate of domain coalescence is controlled by the strength of the protein film. The mechanically stronger (more elastic) β-lactoglobulin films were bette...

This paper argues that Ronald Coase's major contributions to economic theory are best understood in terms of the distinct method he used to build more realistic models of choice. We call his method the benchmark-comparison method. It consists of building models of choice and then using them as benchmarks in the further investigation of economic interaction, either by comparing the benchmark models with observed interaction or by building additional models of choice, which may themselves function as benchmarks. The paper first describes the method then demonstrates how Coase used it in his two most famous papers. We go on to show how an understanding of the method confirms Coase's own statements about the continuity of his thought. Finally, we assess Coase's critique of Milton Friedman's positivist methodology and discuss a recent paper on Coase's methodology.

The digestion of dietary components in the human gastrointestinal (GI) tract is a complex, dynamic, inherently heterogeneous process. A key aspect of the digestion of lipid in the GI tract is the combined action of bile salts, lipase and colipase in hydrolysing and solubilising dispersed lipid. The bile salts are a mixture of steroid acid conjugates with surfactant properties. In order to examine whether the different bile salts have different interfacial properties their dynamic interfacial behaviour was characterised. Differences in the adsorption behaviour to solid hydrophobic surfaces of bile salt species were studied using dual polarisation interferometry and atomic force microscopy (AFM) under physiological conditions. Specifically, the cholates adsorbed more slowly and a significant proportion were irreversibly adsorbed following buffer rinsing; whereas the deoxycholates and chenodeoxycholates adsorbed more rapidly and desorbed to a greater extent following buffer rinsing. The conjugating groups (taurine, glycine) did not influence the behaviour. AFM showed that the interfacial structures that remained following buffer rinsing were also different between these two groups. In addition, the adsorption–desorption behaviour affected the adsorption of colipase to a solid surface. This supports the idea that cooperative adsorption occurs between certain bile salts and colipase to facilitate the adsorption and activity of pancreatic lipase in order to restore lipolytic activity in the presence of bile salts. This study provides insights into how differences in bile salt structure could affect lipase activity and solubilisation of lipolysis products and other lipid-soluble bioactive molecules.

The interaction of the two binding sites of the starch-binding domain (SBD) of Aspergillus niger glucoamylase 1 (GA-I) with substrate has been investigated by using atomic force microscopy (AFM) and UV difference spectroscopy in combination with site-specific mutants of both SBD and GA-I. The SBD possesses two binding sites with distinct affinities towards the soluble linear substrate maltoheptaose; dissociation constants (K(d)) of 17 and 0.95 microM were obtained for W563 K (binding site 2 mutant) and W590 K (binding site 1 mutant), respectively, compared to an apparent K(d) of 23 microM for the wild-type SBD. Further, the two sites are almost but not totally independent of each other for binding, since abolishing one site does not prevent the amylose chain binding to the other site. Using AFM, we show that the amylose chains undergo a conformational change to form loops upon binding to the SBD, using either the recombinant wild-type SBD or a catalytically inactive mutant of GA-I. This characteristic conformation of amylose is lost when one of the SBD binding sites is eliminated by site-directed mutagenesis, as seen with the mutants W563 K or W590 K. Therefore, although each binding site is capable of simple binding to a ligand, both sites must be functional in order to induce a gross conformational change of the amylose molecules. Taken together these data suggest that for the complex with soluble amylose, SBD binds to a single amylose chain, site 1 being responsible for the initial recognition of the chain and site 2 being involved in tighter binding, leading to the circularisation of the amylose chain observed by AFM. Binding of the SBD to the amylose chain results in a novel two-turn helical amylose complex structure. The binding of parallel amylosic chains to the SBD may provide a basis for understanding the role of the SBD in facilitating enzymatic degradation of crystalline starches by glucoamylase 1.

The adsorption of mixed β-casein/β-lactoglobulin films to the air/water interface and the subsequent displacement by the nonionic surfactant Tween 20 was studied. A combination of fluorescent labeling of the protein and Langmuir−Blodgett deposition was used to study the mixed protein layer. The adsorption was also monitored using two surface rheological techniques, shear and dilatation. Fluorescent labeling was able to show that to within the limits of optical resolution the two proteins were well mixed at the interface. We also show that the film remained well mixed after 3 days. Surface rheological data from the two techniques used was self-consistent and showed that during the initial stages of development, the films were dominated by the adsorption of the β-casein. Both fluorescence microscopy and atomic force microscopy were used to follow the displacement of the mixed film by surfactant. Results on films displaced by the nonionic surfactant Tween 20 showed that β-casein was preferentially displaced ...

The displacement of spread protein films from the air/water interface by surfactant was followed using Brewster angle microscopy (BAM) and interfacial rheology. The displacement of beta-lactoglobulin and beta-casein by a nonionic surfactant was monitored as a function of both surface pressure and time. In both cases, protein displacement occurred over the same surface pressure range that had been observed previously by atomic force microscopy (AFM). In the case of the beta-lactoglobulin, surfactant domains grew large enough in the protein film to be visible in the BAM images. The shapes of the domains were very similar to those seen previously by AFM in the late stages of displacement. The results from both proteins confirm the results published previously while highlighting some implications for the application of the "orogenic" model of displacement for large protein films. The surface rheological data showed that the beta-lactoglobulin/surfactant mixed film retained much of its elasticity until the latter stages of displacement. This indicates that at least in the early stages of displacement, the mixed film was dominated by the behavior of the protein in the film.

Scanning near field optical microscopy (SNOM) has been used to visualize phase-separated regions in a monolayer protein film. The film was created at an air−water interface during displacement of the protein bovine serum albumin (BSA) by the nonionic surfactant Tween 20. Contrast was generated in the SNOM images by fluorescent labeling of the protein. The validity of the SNOM methodology has been confirmed by a qualitative and quantitative comparison of the displacement process as visualized by SNOM and atomic force microscopy (AFM) on fluorescently labeled BSA displaced by Tween 20 and AFM data on native BSA displaced by Tween 20. The data suggest that SNOM studies of labeled proteins can be used to investigate the behavior of particular protein species in complex multicomponent interfacial films.

Atomic force microscopy (AFM) is still a relatively new form of microscopy. Unlike conventional microscopes the AFM generates images by feeling the surface of the sample: the microscope senses the changes in force between the surface and a probe as the sample is scanned relative to the probe. An analogy is a blind person who produces images by touch. Much as the blind person can generate images of surface shape, hardness and stickiness, so the AFM can produce images of surface topography, adhesion, elasticity or charge. This mini review will be concerned solely with topographical imaging and its application to study food biopolymers. Current commercial AFMs permit submolecular resolution under gaseous or liquid environments and, under suitable circumstances, it is possible to image molecular processes in real time. This article is intended as a mini review of applications of AFM in food science which permit a molecular understanding of the rheology of food biopolymers.

Seminal plasma proteins and macromolecules in the external medium have a major influence on the functionality of sperm plasma membranes. In this investigation we have examined their effects on lipid diffusion in the surface membrane of ram and bull spermatozoa as measured by fluorescence recovery after photobleaching (FRAP). Results show that progressive removal of seminal plasma from ram spermatozoa by repeated centrifugation and resuspension in media ± 4% bovine serum albumin (BSA) or 0.4% polyvinlypyrrolidone (PVP) causes a reduction in lipid diffusion in all regions of the membrane. By contrast, bull sperm membranes respond with an increase in diffusion in all regions. Repeated washing of bull spermatozoa whose membranes were previously immobile (i.e., showed no recovery after FRAP) restored lipid diffusion suggesting an inhibitory effect of seminal plasma proteins. Further analysis by atomic force microscopy revealed a close association between BSA and the plasma membrane. It is concluded that diffusion of lipids in the plasma membrane of ejaculated ram and bull spermatozoa is influenced by seminal plasma proteins and the composition of the suspending medium. Mol. Reprod. Dev. 59:306–313, 2001. © 2001 Wiley-Liss, Inc.

In this work, the displacement of a globular protein from the air/water interface by sodium dodecyl sulfate (SDS) was followed using a combination of the Langmuir−Blodgett method and atomic force microscopy. The results are compared to displacement of the same protein by the nonionic surfactant Tween 20. The displacement by SDS is characterized by the same orogenic mechanism but the charge interactions between the protein and surfactant served to increase the surface pressure at which displacement occurred. Two types of interfacial film transfer were used in order to check that features seen were not caused by the method of transfer. The displacement was also followed using two surface rheological techniques: shear and dilation. The results from the rheological studies are correlated with the data seen with the AFM and show that the mixed film was much weaker than either of the component films. Both surface shear and dilation rheology showed similar trends. Also demonstrated is the appearance of larger c...

A water-soluble wheat pentosan polysaccharide has been observed in motion by atomic force microscopy (AFM). The motion occurred under aqueous buffer solution and has been attributed to the desorption and readsorption of segments of the molecule from the mica substrate on to which it had been physisorbed. The three classically described states postulated to be involved in polymer adsorption/desorption, namely loops, trains and tails were confirmed by direct observation. These observations validate long held, but largely untested, beliefs about the nature of the adsorption/desorption of polymer chains to surfaces.

In his book on Austrian welfare economics, Roy Cordato presents a scathing criticism of the Coasean approach to making judgments in tort cases. His criticism claims that the Coasean approach is both unrealistic and normative. Moreover, it would introduce uncertainty, thereby reducing individuals' freedom in pursuing their goals through the exchange process. To avoid all of these problems or at least to better deal with them, the economist who is interested in giving advice to judges ought to advocate a rule of strict liability regarding invasions of real (i.e., material) property. He claims that this rule is derived from Austrian economics.

This paper argues that contrary to Roy Cordato's claim, Ronald Coase's work on the “problem of social cost” is an important contribution to Austrian economics. Coase identified a criterion that can be used to establish initial legal rights to control actions that have external effects. In other words, he discovered a criterion that, in some cases, can be directly applied to help establish a property system when there is none. The criterion also helps a government adapt, or maintain, a property system in light of continuing changes that are characteristic of the entrepreneur economy. Cordato's anti-state ethical economics, which he used to criticize Coase, is a deviation from the century-old tradition of Austrian economics. Menger, Mises and Hayek saw economics as a body of logical knowledge that is value free. In addition they recognized a role for government in defining legal rights and in maintaining the property system in light of changing conditions. Accordingly, it is wrong to invoke “Austrian economics,” properly understood, to criticize this aspect of Coase's work. In this paper, I argue that Cordato has followed a deviant and troubling path by trying to construct an Austrian economics based on ethics, that he has failed to understand that a changeable property system is a prerequisite for the market economy, and that he has correspondingly failed to recognize Coase's contribution to the problem of how to maintain the property system in light of continuing change.

Orogenic displacement has been shown to be a mechanism by which protein can be removed from an interface by small surfactant molecules. This paper describes the progressive displacement of two diff...

Atomic force microscopy has been used to visualize, in real time, the breakdown and removal of a β-lactoglobulin film from a graphite surface, by the addition of the nonionic surfactant Tween 20 to the liquid cell of the microscope. The initial stage of surfactant adsorption onto the graphite surface is seen to involve the nucleation of small surfactant domains within the protein network. These surfactant domains expand, compressing the protein network. The reduction in surface area covered by protein is compensated by an increase in the thickness of the protein film. Eventually, at sufficiently high surface concentration of surfactant, the protein network fractures allowing release of protein for displacement from the surface. The displacement mechanism observed at the graphite surface has been compared with the displacement by Tween 20 of a spread β-lactoglobulin protein layer from an air−water interface. In both cases a similar “orogenic” mechanism of displacement has been observed. The present studies...

The bubbles in a pure protein foam are stabilized by elastic networks of protein molecules that adsorb to the air/water interface through hydrophobic interaction. In real systems, however, there are often other amphiphiles present that have an antagonistic effect on the stability of the foam. This paper describes the first direct observation of specific heterogeneous structures that occur during the competitive adsorption between proteins and surfactants. This is in contrast to the previous assumption of a homogeneous distribution of the two competing species at the interface. By using atomic force microscopy to visualize the breakdown of protein networks, we have identified the specific mechanism for surfactant displacement of proteins from an air/water interface. This mechanism, which we have termed an orogenic model of protein displacement, involves nucleation and growth of surfactant domains that compress and then fracture the protein network, eventually inducing its displacement from the interface.

The loan fund theory of capital was developed by the unheralded American economist, Herbert J. Davenport (1861-1931). Davenport's name has virtually disappeared from writings on the history of economic thought. Today, he seems best known as a teacher of Frank Knight at Cornell around 1915. Davenport wrote three major books during an 18-year period between 1896 and 1914. The first (1896) was a treatise based on what he called the “principle of sacrifice,” or subjective opportunity cost. His second book, Value and Distribution (1908), covered much of the same ground but also presented some original contributions. It marked his emergence as a professional economist, since he presented his ideas within the context of an appraisal of classical and neoclassical economic doctrine. Among other things, the book contained a penetrating, subjectivist critique of four ideas in the history of subjectivist economics: marginal utility, Eugen von Bohm-Bawerk's theory of capital, Friedrich Wieser's theory of cost, and Frank Fetter's theory of market interest. It also introduced the loan fund theory of capital, which is the topic of this paper.