The effect of metal ion content on the viscosity of gum ghatti

Cold water extraction of gum ghatti gives a soluble gum and an insoluble gel. The two fractions were shown by potentiometric titration to have the same acid equivalent weight and to be largely in the salt form, with less than 10% in the free acid form. Quantitative analysis of the two fractions for metal ion content showed that the gel fraction was largely a calcium salt. The soluble fraction contains calcium, potassium, sodium, and magnesium. Precipitation of the calcium ions reduces the viscosity but the original viscosity is not restored by addition of calcium ions.     

Effect of different condensed tannin‐containing forages,forage maturity and nitrogen fertiliser application on the formation of indole and skatole in in vitro rumen fermentations

The objectives of this work were to establish the effect of seven different forages with a varied condensed tannin (CT) content, plant maturity and nitrogen fertiliser application on the ruminal formation of skatole and indole using an in vitro method designed to mimic rumen fermentation conditions. After 10 h of incubation, the concentration of indole and skatole was highest when incubating white clover (P < 0.05). Polyethylene glycol addition, to inhibit CT, showed that CT significantly reduced the formation of indole and skatole when incubating Lotus corniculatus, sulla, Dorynium rectum and Lotus pedunculatus (P < 0.01). Mature forage growth resulted in a significantly lower concentration of indole and skatole being formed in vitro compared to the incubation of new spring growth (P < 0.001). A higher application of nitrogen fertiliser to perennial ryegrass‐based pasture resulted in a higher crude protein concentration in the plant and a significantly higher concentration of skatole formed in vitro (P < 0.001). Forages containing CT reduced the conversion of endogenous protein to indole and skatole and plants containing a higher CT concentration tended to be more effective, but compositional differences of CT between forages may also have had an influence. New forage growth or swards that had a high application of nitrogen fertiliser promoted the formation of indole and skatole. Copyright © 2007 Society of Chemical Industry     

Functional Properties of Vinegar

A variety of natural vinegar products are found in civilizations around the world. A review of research on these fermented products indicates numerous reports of health benefits derived by consumption of vinegar components. Therapeutic effects of vinegar arising from consuming the inherent bioactive components including acetic acid, gallic acid, catechin, ephicatechin, chlorogenic acid, caffeic acid, p‐coumaric acid, and ferulic acid cause antioxidative, antidiabetic, antimicrobial, antitumor, antiobesity, antihypertensive, and cholesterol‐lowering responses. The aims of this article are to discuss vinegar history, production, varieties, acetic acid bacteria, and functional properties of vinegars.     

The archetype-genome exemplar in molecular dynamics and continuum mechanics

We argue that mechanics and physics of solids rely on a fundamental exemplar: the apparent properties of a system depend on the building blocks that comprise it. Building blocks are referred to as archetypes and apparent system properties as the system genome. Three entities are of importance: the archetype properties, the conformation of archetypes, and the properties of interactions activated by that conformation. The combination of these entities into the system genome is called assembly. To show the utility of the archetype-genome exemplar, this work presents the mathematical ingredients and computational implementation of theories in solid mechanics that are (1) molecular and (2) continuum manifestations of the assembly process. Both coarse-grained molecular dynamics (CGMD) and the archetype-blending continuum (ABC) theories are formulated then applied to polymer nanocomposites (PNCs) to demonstrate the impact the components of the assembly triplet have on a material genome. CGMD simulations demonstrate the sensitivity of nanocomposite viscosities and diffusion coefficients to polymer chain types (archetype), polymer–nanoparticle interaction potentials (interaction), and the structural configuration (conformation) of dispersed nanoparticles. ABC simulations show the contributions of bulk polymer (archetype) properties, occluded region of bound rubber (interaction) properties, and microstructural binary images (conformation) to predictions of linear damping properties, the Payne effect, and localization/size effects in the same class of PNC material. The paper is light on mathematics. Instead, the focus is on the usefulness of the archetype-genome exemplar to predict system behavior inaccessible to classical theories by transitioning mechanics away from heuristic laws to mechanism-based ones. There are two core contributions of this research: (1) presentation of a fundamental axiom—the archetype-genome exemplar—to guide theory development in computational mechanics, and (2) demonstrations of its utility in modern theoretical realms: CGMD, and generalized continuum mechanics.     

Neuronal diversity in the subiculum: correlations with the effects of somatostatin on intrinsic properties and on GABA-mediated IPSPs in vitro

1. We used intracellular current-clamp techniques to record from 33 ventral subicular neurons in slices or rat hippocampal formation. Presumed pyramidal neurons were characterized by their responses to depolarizing current pulses as either intrinsically burst firing (IB) or regular spiking (RS). Within the subiculum, IB cells were encountered most frequently in the deep cell layer, whereas RS cells were encountered most frequently in the superficial cell layer. IB cells had more depolarized resting potentials, lower input resistances, and more sag in their voltage responses to hyperpolarizing current pulses. 2. Somatostatin (5 microM) applied in the bathing medium caused a hyperpolarization and reduction in input resistance. These effects were of greater magnitude in IB cells. Somatostatin had no effect on sag in either cell type. These effects of somatostatin were unchanged in the presence of gamma-aminobutyric acid (GABA) receptor antagonists. 3. In a series of experiments conducted in RS cells only, somatostatin reduced the amplitude of the late but not the early component of evoked biphasic inhibitory postsynaptic potentials (IPSPs). 4. A second series of experiments was conducted in RS and IB cells. Somatostatin reduced the amplitude of pharmacologically isolated GABAA IPSPS in both cell types. In IB cells but not RS cells there was a correlation between this effect and the somatostatin-induced hyperpolarization. Somatostatin also reduced the amplitude of isolated GABAB IPSPS in both cell types, but more so in IB cells. 5. Somatostatin had no effect on the reversal potential of either IPSP in either cell type and no effect on the GABAA-mediated conductance in either cell type. In contrast, the GABAB-mediated conductance was reduced, especially in IB cells. 6. The effects of somatostatin on GABAA IPSPS are principally a result of membrane shunting and reductions in ionic driving force, but these mechanisms do not account for the reduction in GABAB IPSPS. 7. We suggest that the combined effects of somatostatin are likely to alter the balance between fast and slow inhibition and to do so more in IB cells than in RS cells.     

Temporal rescaling of simple and complex ratios in rhythmic tapping.

Two well-established phenomena in temporal performance—preference for simple ratios over complex ratios and the ability to proportionately rescale temporal patterns—were examined together. Unlike the case with simple ratios, participants (3 trained musicians) showed only a limited ability to learn complex ratios and no ability to proportionately rescale them. These differences suggest that different mechanisms are used to produce the 2 ratio types. Systematic biases observed in the performances of the simple ratios (6 trained musicians) were modeled by assuming that an additive timing component, which is unequal for short and long intervals and changes with base rate, overlays a system that preferentially produces simple ratios. The general pattern of results was consistent with the view that rhythmic learning builds on or modifies a system of innate preferences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the generality of the revelation effect.

Seven experiments demonstrate the robustness of the revelation effect, which is the tendency to call recognition test items old if they are distorted when they initially appear and if they are revealed before the recognition judgment. With anagrams as the distortion, a revelation effect was found in within- and between-subjects designs, in a frequency-judgment task, in a list-discrimination task, when new items were used as targets, when the study list and the test were presented in different modalities, and when the word that was revealed did not match the word that was recognized. These results challenge accounts that attribute the revelation effect either to an increase in the familiarity of the revealed test word or to a positive response bias. (PsycINFO Database Record (c) 2010 APA, all rights reserved)