Enumerating and indexing many-body intramolecular interactions:a graph theoretic approach

The central idea observes a recursive mapping of -body intramolecular interactions to -body terms that is consistent with the molecular topology. Iterative application of the line graph transformation is identified as a natural and elegant tool to accomplish the recursion. The procedure readily generalizes to arbitrary -body potentials. In particular, the method yields a complete characterization of -body interactions. The hierarchical structure of atomic index lists for each interaction order is compactly expressed as a directed acyclic graph. A pseudo-code description of the generating algorithm is given. With suitable data structures (e.g., edge lists or adjacency matrices), automatic enumeration and indexing of -body interactions can be implemented straightforwardly to handle large bio-molecular systems. Explicit examples are discussed, including a chemically relevant effective potential model of taurocholate bile salt

Influence of oat components on lipid digestion using an in vitro model: impact of viscosity and depletion flocculation mechanism

Depletion flocculation is a well-known instability mechanism that can occur in oil-in-water emulsions when the concentration of non-adsorbed polysaccharide exceeds a certain level. This critical flocculation concentration depends on the molecular characteristics of the polysaccharide molecules, such as their molecular weight and hydrodynamic radius. In this study, a range of analytical methods (dynamic shear rheology, optical microscopy, and static light-scattering) were used to investigate the interaction between lipid droplets and polysaccharides (guar gum and β-glucans) of varying weight-average molecular weight and hydrodynamic radius, and concentration. The aim of this work was to see if the health benefits of soluble fibers like β-glucans could be explained by their influence on the structure and digestibility of lipid emulsions. The apparent viscosity of the emulsions increased with increasing polysaccharide concentration, molecular weight, and hydrodynamic radius. Droplet flocculation was observed in the emulsions only at certain polysaccharide concentrations, which was attributed to a depletion effect. In addition, the water-soluble components in oat flakes, flour, and bran were extracted using aqueous solutions, to examine their impact on emulsion stability and properties. Then, the rate and extent of lipolysis of a sunflower oil-in-water emulsion in the presence of these oat extracts were monitored using the pH-stat method. However, the inhibition of lipolysis was not linearly related to the viscosity of the oat solutions. The water-soluble extracts of β-glucan collected from oat flakes had a significant inhibitory effect on lipolysis. The results of this study increase our understanding of the possible mechanisms influencing the impact of oat constituents on lipid digestion. This work also highlights the importance of considering the molecular properties of polysaccharides, and not just their impact on solution viscosity

Quercetin solubilisation in bile salts: A comparison with sodium dodecyl sulphate

AbstractTo understand the bioaccessibility of the flavonoid quercetin we studied its interaction with bile salt micelles. The environmental sensitivity of quercetin’s UV–visible absorption spectrum gave information about quercetin partitioning. Two quercetin absorption peaks gave complementary information: Peak A (240–280nm) on the intermicellar phase and Peak B (340–440nm) on the micellar phase. Thus, by altering pH, we showed that only non-ionised quercetin partitions into micelles. We validated our interpretation by studying quercetin’s interaction with SDS micelles. Pyrene fluorescence and the quercetin UV–visible spectra show that the adsorption site for pyrene and quercetin in bile salt micelles is more hydrophobic than that for SDS micelles. Also, both quercetin and pyrene reported a higher critical micelle concentration for bile salts than for SDS. Our method of using a flavonoid as an intrinsic probe, is generally applicable to other lipophilic bioactives, whenever they have observable environmental dependent properties

Oat and lipolysis: food matrix effect

Oat is rich in a wide range of phytochemicals with various physico-chemical, colloidal and interfacial properties. These characteristics are likely to influence human lipid metabolism and the subsequent effect on health following oat consumption. The aim of this work was to investigate the impact of oat materials varying in complexity on the lipolysis process. The composition, structure and digestibility of different lipid systems (emulsions, oil bodies and oil enriched in phytosterols) were determined. The surface activities of phytosterols were examined using the pendant drop technique. Differences in lipid digestibility of the oat oil emulsions and the oil bodies were clearly seen. Also, the digestion of sunflower oil was reduced proportionally to the concentration of phytosterols present. This may be due to their interfacial properties as demonstrated by the pendant drop experiments. This work highlights the importance of considering the overall structure of the system studied and not only its composition

Telecommunications in Scotland : auditing the issues

The study upon which this article is based was concerned with the uptake and use of telecommunication services in the Scottish economy. It was also concerned with the formulation and implementation of public policy designed to encourage the uptake of telecommunication services. Its specific objectives were : (a) To uncover telecommunications issues as perceived at the level of individual businesses in Scotland. This part of the work was undertaken through a survey of Scottish Business in six LEC areas and in three sectors - Software, Mechanical Engineering and Textiles. (b) To uncover telecommunications issues as perceived in interviews with officials in selected organisations which have key representative, advisory and policy influencing roles within the Scottish economy. This part of the work was conducted through interviews

Private Schools and the Provision of ‘Public Benefit’

Legislative changes and a recent court ruling allow private schools in England and Wales to determine how to provide the public benefits required to justify their charitable status. We investigate how private school headteachers and other informed stakeholders perceive their public benefit objectives and obligations. We find that schools interpret public beneficiaries widely to include one or more of state school pupils, local communities, other charities, and general society through raising socially responsible adults. Private schools pursue their own goals through public benefit provision, and balance the advantages of public benefit activities against the costs. The schools are not constrained by the ‘more than tokenistic’ minimum set by the regulator. The findings highlight the difficulties faced by governments who seek to pursue redistributive educational policies through charitable law

The Process of Organ Donation from Non-Living Donors: A Case-Based Journey from Potential Donor Identification to Organ Procurement

Each year, thousands of people worldwide succumb to end-organ failure while awaiting life-saving transplantation procedures. The shortage of organs continues with no signs of easing in the foreseeable future. The availability of organs from living donors continues to be constrained. At the same time, the cumulative knowledge of organ preservation is advancing steadily resulting in an enhanced ability to utilize a growing number of previously unsuitable tissue and organ gifts. Our ability to procure and preserve more organs is accompanied by the increasing use of so-called “expanded criteria” donors, or those whose organs may not have been suitable without modern advances in organ preservation science. Within the overall context of organ donation from non-living donors, the importance of physiologic and end-organ optimization cannot be understated. This chapter discusses our current state of understanding of optimized organ procurement approaches derived from practical experiences and “lessons learned” at a high-performing, community-based tertiary referral hospital

Clustering approaches to improve the performance of low cost air pollution sensors

Low cost air pollution sensors have substantial potential for atmospheric research and for the applied control of pollution in the urban environment, including more localized warnings to the public. The current generation of single-chemical gas sensors experience degrees of interference from other co-pollutants and have sensitivity to environmental factors such as temperature, wind speed and supply voltage. There are uncertainties introduced also because of sensor-to-sensor response variability, although this is less well reported. The sensitivity of Metal Oxide Sensors (MOS) to volatile organic compounds (VOCs) changed with relative humidity (RH) by up to a factor of five over the range 19-90%RH and with an uncertainty in the correction of a factor two at any given RH. The short-term (second to minute) stabilities of MOS and electrochemical CO sensor responses were reasonable. During more extended use inter-sensor quantitative comparability was degraded due to unpredictable variability in individual sensor responses (to either measurand or interference or both) drifting over timescales of several hours to days. For timescales longer than a week identical sensors showed slow, often downwards, drifts in their responses which diverged across six CO sensors by up to 30% after two weeks. The measurement derived from the median sensor within clusters of 6, 8 and up to 21 sensors was evaluated against individual sensor performance and external reference values. The clustered approach maintained the cost competitiveness of a sensor device, but the median concentration from the ensemble of sensor signals largely eliminated the randomised hour-to-day response drift seen in individual sensors and excluded the effects of small numbers of poorly performing sensors that drifted significantly over longer time periods. The results demonstrate that for individual sensors to be optimally comparable to one another, and to reference instruments, they would likely require frequent calibration. The use of a cluster median value eliminates unpredictable medium term response changes, and other longer term outlier behaviours, extending the likely period needed between calibration and making a linear interpolation between calibrations more appropriate. Through the use of sensor clusters rather than individual sensors existing low cost technologies could deliver significantly improved quality of observations

Spectrophotometric, chemometric and chromatographic determination of naphazoline hydrochloride and chlorpheniramine maleate in the presence of naphazoline hydrochloride alkaline degradation product

AbstractFour accurate and sensitive methods were developed and validated for determination of naphazoline hydrochloride (NAP) and chlorpheniramine maleate (CLO) in the presence of naphazoline hydrochloride alkaline degradation product (NAP Deg). The first method is a spectrophotometric one , where NAP was determined by the fourth derivative (D4) spectrophotometric method by measuring the peak amplitude at 302nm, while CLO was determined by the second derivative of the ratio spectra (DD2) spectrophotometric method at 276.4nm. The second method is a chemometric-assisted spectrophotometric method in which partial least squares (PLS-1) and partial component regression (PCR) were used for the determination of NAP, CLO and NAP Deg using the information contained in their absorption spectra of ternary mixture. The third method is a TLC-densitometric one where NAP, CLO and NAP Deg were separated using HPTLC silica gel F254 plates using ethyl acetate:methanol:ammonia: (8:2:0.5, by volume) as the developing system followed by densitometric measurement at 245nm. The fourth method is HPLC method where NAP, CLO and NAP Deg were separated using ODS C18 column and a mobile phase consisting of 0.1M KH2PO4 (pH=7):methanol (55:45 v/v) delivered at 1.5mLmin−1 followed by UV detection at 265nm. The proposed methods have been successfully applied to the analysis of NAP and CLO in pharmaceutical formulations without interference from the dosage form additives and the results were statistically compared with a reported method