Acoustically controlled enhancement of molecular sensing to assess oxidative stress in cells

We demonstrate a microfluidic platform for the controlled aggregation of colloidal silver nanoparticles using surface acoustic waves (SAWs), enabling surface enhanced Raman scattering (SERS) analysis of a cell based model for oxidative damage. We show that by varying the frequency and the power of the acoustic energy, it is possible to modulate the aggregation of the colloid within the sample and hence to optimise the SERS analysis

The development of private bore-wells as independent water supplies: challenges for water utilities in France and Australia

International audienceIn developed countries, a number of factors are leading a growing number of households to drill private boreholes as independent water supplies. This chapter describes this phenomenon based on two case studies conducted in Southern France and Western Australia. It shows that, while the development of private wells was encouraged by the authorities in Perth, it is a major source of environmental, public health, economic and social concern for French water utilities. Household's motivations to develop independent supply are then investigated. We finaly discuss how water utilities need to adapt their management practices (setting tariffs, demand forecasting and resource protection) to take into account this phenomenon

Perceptions of Social Mobility: Development of a New Psychosocial Indicator Associated with Adolescent Risk Behaviors

Social class gradients have been explored in adults and children, but not extensively during adolescence. The first objective of this study was to examine the association between adolescent risk behaviors and a new indicator of adolescent relative social position, adolescent “perceived social mobility.” Second, it investigated potential underlying demographic, socioeconomic, and psychosocial determinants of this indicator. Data were taken from the 2004 urban adolescent module of Oportunidades, a cross-sectional study of Mexican adolescents living in poverty. Perceived social mobility was calculated for each subject by taking the difference between their rankings on two 10-rung ladder scales that measured (1) projected future social status and (2) current subjective social status within Mexican society. Adolescents with higher perceived social mobility were significantly less likely to report alcohol consumption, drinking with repercussions, compensated sex, police detainment, physical fighting, consumption of junk food or soda, or watching ≥4 h of television during the last viewing. They were significantly more likely to report exercising during the past week and using a condom during last sexual intercourse. These associations remained significant with the inclusion of covariates, including parental education and household expenditures. Multiple logistic regression analyses show higher perceived social mobility to be associated with staying in school longer and having higher perceived control. The present study provides evidence for the usefulness of perceived social mobility as an indicator for understanding the social gradient in health during adolescence. This research suggests the possibility of implementing policies and interventions that provide adolescents with real reasons to be hopeful about their trajectories

Phonon drag thermopower and weak localization

Previous experimental work on a two-dimensional (2D) electron gas in a Si-on-sapphire device led to the conclusion that both conductivity and phonon drag thermopower $S^g$ are affected to the same relative extent by weak localization. The present paper presents further experimental and theoretical results on these transport coefficients for two very low mobility 2D electron gases in $\delta-$doped GaAs/Ga$_x$Al$_{1-x}$As quantum wells. The experiments were carried out in the temperature range 3-7K where phonon drag dominates the thermopower and, contrary to the previous work, the changes observed in the thermopower due to weak localization were found to be an order of magnitude less than those in the conductivity. A theoretical framework for phonon drag thermopower in 2D and 3D semiconductors is presented which accounts for this insensitivity of $S^g$ to weak localization. It also provides transparent physical explanations of many previous experimental and theoretical results.Comment: 19 page Revtex file, 3 Postscript figur

Experiments on the Preparation of Aminohydroxynaphthoic Acids

Some suggested methods for the preparation of aminohydroxynaphthoic acids have been investigated. The main part of the research was devoted to the preparation of those having the -NH2 group in the 2-position, and the particular one desired was the 2-amino-5-hydroxy-7-naphthoic acid. The scheme, outlined on pages 13 and 14, shows that the -OH group was to be introduced by sulphonation and subsequent alkali fusion of 2:7-aminonaphthoic acid. Consequently the first consideration was the preparation of 2:7-aminonaphthoic acid. The formation of 2:7-aminonaphthonitrile by replacement of -SO3H by -CN by the dry distillation of 2:7-aminonaphthalene sulphonic acid with KCN and K4Fe(CN)6 gave very poor yields, insufficient for the subsequent series of reactions, while fusion with KCN under pressure eliminated the -SO3H group. The diazotisation of 2:7-aminonaphthol was successfully accomplished by the usual Greiss reaction in the presence of a large excess of HCl; also after the method of Hodgson & Walker, and that of Schoutissen, but attempts to form the 2:7-cyanonaphthol by the Sandmeyer reaction and various modifications of same failed due to the preference of the diazo compound to couple with itself. The diazotisation of 2:7-diaminonaphthalene was accomplished using a modification of the method of Schoutissen, but attempts to form the 2:7-aminonaphthonitrile failed. 2:7-Aminonaphthoic acid was synthesised from 2:7-aminonaphthalene sulphonic acid by the series of reactions outlined on page 82 and described on pages 120-136, and successfully sulphonated but the yield of sulphonic acid was poor. The same result was obtained with chlorosulphuric acid. Sulphonation of the acetyl derivative gave excellent yields, but isomers were present and various attempts to separate them were unsuccessful, while conversion to the aminohydroxynaphthoic acids by alkali fusion yielded oxidation products. Estimation of the alpha-SO3H groups in the sulphonation mixture gave 60%. It would appear, judging from results on page 125, that about 40% of the sulphonic mixture contains the -SO3H group in the 6-position. The preparation of 1:2:7- and 1:2:6-aminohydroxynaphthoic acids was accomplished by method 1. They were obtained as the hydrochlorides since the free bases oxidise very rapidly in the air. The action of nitrous acid on 2:7- and 2:6-hydroxy-naphthoic acids gave highly coloured products containing no nitrogen. A table of properties is given on page 189

Control over phase separation and nucleation using a laser-tweezing potential

Control over the nucleation of new phases is highly desirable but elusive. Even though there is a long history of crystallization engineering by varying physicochemical parameters, controlling which polymorph crystallizes or whether a molecule crystallizes or forms an amorphous precipitate is still a poorly understood practice. Although there are now numerous examples of control using laser-induced nucleation, the absence of physical understanding is preventing progress. Here we show that the proximity of a liquid–liquid critical point or the corresponding binodal line can be used by a laser-tweezing potential to induce concentration gradients. A simple theoretical model shows that the stored electromagnetic energy of the laser beam produces a free-energy potential that forces phase separation or triggers the nucleation of a new phase. Experiments in a liquid mixture using a low-power laser diode confirm the effect. Phase separation and nucleation using a laser-tweezing potential explains the physics behind non-photochemical laser-induced nucleation and suggests new ways of manipulating matter

Characterisation of feline renal cortical fibroblast cultures and their transcriptional response to transforming growth factor beta 1

Chronic kidney disease (CKD) is common in geriatric cats, and the most prevalent pathology is chronic tubulointerstitial inflammation and fibrosis. The cell type predominantly responsible for the production of extra-cellular matrix in renal fibrosis is the myofibroblast, and fibroblast to myofibroblast differentiation is probably a crucial event. The cytokine TGF-β1 is reportedly the most important regulator of myofibroblastic differentiation in other species. The aim of this study was to isolate and characterise renal fibroblasts from cadaverous kidney tissue of cats with and without CKD, and to investigate the transcriptional response to TGF-β1

The Angular Distribution of Photoneutrons From O16

The relative importance of competing reaction channels in the photo-excitation of the giant resonance in O16 has been studied by measurement of the angular distribution of the emitted photo-neutrons through the corresponding energy range using a multi-angle neutron time of flight spectrometer installed at the Kelvin Laboratory of the University of Glasgow. Design factors for the spectrometer are discussed with regard to optimisation of energy resolution and counting rates under the constraints of the source, and the obtainable accuracy of normalisation between neutron detectors at different angles has been measured, A reliable method of calibration of the neutron energy scale at each angle is described and corrections to the neutron spectra for absorption by materials in the flight path have been made. The energy dependent efficiency of the neutron detectors is calculated in an appendix by a Monte Carlo technique using a new measurement of the scintillation response curve for recoil protons. Angular distributions of photoneutrons from the D2 (gamma,n)p reaction with 26.9 MeV bremsstrahlung have been measured and are found to agree with previously published results and theoretical predictions to within the expected accuracy. This is taken as confirmation of good angular normalisation in the system. Measurements by the author of the angular distributions of photo-neutrons from 26.9 MeV bremsstrahlung on O16 are presented and absolute cross sections have been obtained with respect to that known for deuterium. Photoproton data from other authors is analysed in a similar way for comparison with the photoneutron results. In the E1 approximation, the relative intensity of s/d wave admixture is found to follow the resonance structure for both protons and neutrons and the corresponding phase difference is found to vary about the value expected from optical model predictions. The E2 cross section has been extracted from the data and is found to rest mainly in two broad states centred at about 23 MeV and 24.7 MeV, while a Barker-Mann analysis shows the isospin impurity in the O16 giant resonance to be small and to be mainly associated with the regions of E2 strength. The pure 1p1h dipole approximation fails to describe these features and the observed splitting of the giant resonance in O16 but the presence of more complicated excitations is shown to be more consistent with experiment

Ranking ligand affinity for the DNA minor groove by experiment and simulation

The structural and thermodynamic basis for the strength and selectivity of the interactions of minor-groove binders (MGBs) with DNA is not fully understood. In 2003 we reported the first example of a thiazole containing MGB that bound in a phase shifted pattern that spanned 6 base-pairs rather than the usual 4 (for tricyclic distamycin-like compounds). Since then, using DNA footprinting, nuclear magnetic resonance spectroscopy, isothermal titration calorimetry and molecular dynamics, we have established that the flanking bases around the central 4 being read by the ligand have subtle effects on recognition. We have investigated the effect of these flanking sequences on binding and the reasons for the differences and established a computational method to rank ligand affinity against varying DNA sequences