Aggregation and coalescence of partially crystalline emulsion drops investigated using optical tweezers.

The solid content of viscoelastic emulsion drops is known to affect their propensity for aggregation and their subsequent coalescence behaviour, where the balance between the drive to reduce surface tension and the straining of an internal viscoelastic network is able to create a plethora of stable partially-coalesced states. The latter has previously been elegantly demonstrated in synthetic systems, generated using oil containing different phase volumes of added solids, with micro-pipette experiments carried out on emulsion drops of several tens of microns in size. Herein we carry out experiments in the same spirit but aided by optical tweezers (OT) and using smaller micron-sized emulsion drops generated from milk fat. Given the size dependence of Brownian fluctuations and Laplace pressure the experimental investigation of these smaller drops is not necessarily a trivial extension of the previous work. The solid content of initially separated drops is controlled using a temperature-cycling regime in the sample preparation protocol, and subsequently the propensity for drops to remain joined or not after being brought into contact was examined. Aggregated pairs of drops were then subjected to an increase in temperature, either locally using a high-powered laser, or more globally using a custom-made Peltier temperature-controller. By heating to different degrees, the amount of fat crystals in the drops was able to be controlled, with progressively more compact partially-coalesced states, and eventually complete coalescence generated as the solid content was reduced. While in contrast to previous studies, the emulsion studied here was quite different in size and nature, and the solid content was controlled using temperature, the same underlying physics was nevertheless observed.

Body temperature measurement in anesthetized dogs - comparison of nasal, axillary, rectal and esophageal temperature.

OBJECTIVE: To evaluate different methods of monitoring body temperature in anesthetized dogs with comparison to core temperature obtained via esophageal probe. METHODS: Client-owned dogs undergoing general anesthesia for various procedures were included in this observational study. The temperature was taken sequentially every 10 minutes from the rectum, axilla, and nasal cavity with a digital thermistor thermometer, and compared to esophageal core temperature via paired t-tests. Differences from the gold standard esophageal temperature were assessed via Bland-Altman plots and further evaluated for factors like time under anesthesia and presence of Hypo-/Normo- or Hyperthermia. In addition, it was analyzed whether a correction factor for peripheral measurement sites (nasal cavity and axilla) would be applicable in a reliable representation of the body temperature. The level of significance in all tests was set at p<0.05. RESULTS: In this study, 95 simultaneous temperature measurements at the 4 different sites were obtained from 30 dogs. Mean difference and limits of agreement from esophageal temperature for the different measurement methods were 0.0±0.72°C for rectal temperature, -1.2±1.42°C for axillary and -1.0±2.02°C for nasal temperature. Axillary and nasal temperatures were not significantly different (p=0.5721 and p=0.9287, respectively) from esophageal temperature with a +1.2°C and +1°C correction factor, respectively. CONCLUSION AND CLINICAL RELEVANCE: During perioperative temperature measurement in anesthetized patients, rectal and esophageal measurements can be used interchangeable. However, if these are not available, the use of axillary or nasal sites is only reliable after applying a correction factor.

The use of confocal Raman microscopy and microfluidic channels to monitor the location and mobility of ß-carotene incorporated in droplet-stabilized oil-in-water emulsions.

This study sought to explore the combined use of confocal Raman microscopy and microfluidic channels to probe the location and mobility of hydrophobic antioxidant (ß-carotene) incorporated at the interface of food-grade droplet-stabilized emulsions (DSEs). Microfluidic channels were used to isolate emulsion droplets for efficient investigation of antioxidant mobility. This approach proved more conclusive than fixing the sample in agarose, because a single layer of droplets could be obtained. Results also indicated that the migration of ß-carotene incorporated in shell droplets of olive oil and trimyristin DSEs to core droplets was minimal and beta-carotene remained mostly localised at the interface even after 3 days of production. This work demonstrates that microfluidic isolation of emulsion droplets combined with confocal Raman microscopy can give new insights into the spatial variation of chemical composition within emulsions. This study revealed that the migration of ß-carotene between shell and core was minimal and hence it may be possible to concurrently deliver two incompatible compounds by spatially segregating them between shell and core compartments of DSEs.

Inside the ensemble: unlocking the potential of one-at-a-time experiments with lab-on-a-chip automation.

The advent of technologies that allow the interactions of individual microscopic particles to be probed "one-at-a-time" has paved the way for new experimental avenues of enquiry in colloidal systems. For example, investigating whether a particular pair of colloidal particles isolated from a macroscopic sample might adhere to each other when brought into close proximity is certainly possible. However, given the probabilistic nature of the process (different particles within the ensemble may have slightly different surface charge distributions and asperities, and interaction energies involved can be close to thermal values), it is important that many hundreds or thousands of pairs of particles are tested under each set of experimental conditions of interest. Currently it is still an arduous task to perform such an experiment a sufficient number of times in order to acquire a data-set that truly represents the ensemble. Herein an automated particle collider for measuring particle-particle interactions has been realized by combining elements of microfluidics, holographic optical tweezers and image processing. Each individual measurement consists of confining two particles within a predetermined chemical micro-environment, and observing whether their interactions lead to aggregation. To automate the measurements, computer software consisting of LabVIEW and Red Tweezers with a custom plugin was used. Preliminary experiments carried out using 1 µm diameter polystyrene particles demonstrated that many hundreds of pairwise-interaction measurements could be carried out autonomously within a matter of hours. Further exemplar real-world experiments, designed to examine the stickiness of emulsion drops as a function of bulk measurements of the ζ-potential (zeta potential) of the sample, were then performed. It is envisaged that such robust approaches to the automation of "one-at-a-time" experiments will find applications in a large number of areas, and enable previously unthinkable experiments to be carried out in a timely fashion, thus allowing the focus to shift away from tedious experimental frustrations to more profound scientific questions.

The need to integrate legacy nitrogen storage dynamics and time lags into policy and practice.

Increased fluxes of reactive nitrogen (Nr), often associated with N fertilizer use in agriculture, have resulted in negative environmental consequences, including eutrophication, which cost billions of dollars per year globally. To address this, best management practices (BMPs) to reduce Nr loading to the environment have been introduced in many locations. However, improvements in water quality associated with BMP implementation have not always been realised over expected timescales. There is a now a significant body of scientific evidence showing that the dynamics of legacy Nr storage and associated time lags invalidate the assumptions of many models used by policymakers for decision making regarding Nr BMPs. Building on this evidence, we believe that the concepts of legacy Nr storage dynamics and time lags need to be included in these models. We believe the biogeochemical research community could play a more proactive role in advocating for this change through both awareness raising and direct collaboration with policymakers to develop improved datasets and models. We anticipate that this will result in more realistic expectations of timescales for water quality improvements associated with BMPs. Given the need for multi-nutrient policy responses to tackle challenges such as eutrophication, integration of N stores will have the further benefit of aligning both researchers and policymakers in the N community with the phosphorus and carbon communities, where estimation of stores is more widespread. Ultimately, we anticipate that integrating legacy Nr storage dynamics and time lags into policy frameworks will better meet the needs of human and environmental health.

Putting the Nonsocial Into Social Neuroscience: A Role for Domain-General Priority Maps During Social Interactions.

Whether on a first date or during a team briefing at work, people's daily lives are inundated with social information, and in recent years, researchers have begun studying the neural mechanisms that support social-information processing. We argue that the focus of social neuroscience research to date has been skewed toward specialized processes at the expense of general processing mechanisms with a consequence that unrealistic expectations have been set for what specialized processes alone can achieve. We propose that for social neuroscience to develop into a more mature research program, it needs to embrace hybrid models that integrate specialized person representations with domain-general solutions, such as prioritization and selection, which operate across all classes of information (both social and nonsocial). To illustrate our central arguments, we first describe and then evaluate a hybrid model of information processing during social interactions that (a) generates novel and falsifiable predictions compared with existing models; (b) is predicated on a wealth of neurobiological evidence spanning many decades, methods, and species; (c) requires a superior standard of evidence to substantiate domain-specific mechanisms of social behavior; and (d) transforms expectations of what types of neural mechanisms may contribute to social-information processing in both typical and atypical populations.

Challenges and opportunities for top-down modulation research in cognitive psychology.

Studying social modulation of cognitive processes holds much promise for illuminating how, where, when and why social factors influence how we perceive and act in the world, as well as providing insight into the underlying cognitive mechanisms. This is no small objective; it reflects an ambitious programme of research. At present, based on the modal theoretical and methodological approach, we suggest that several challenges exist to achieving such lofty aims. These challenges span an overreliance on a simplistic dichotomy between "top-down" and "bottom-up" modulation, a lack of specificity about mechanisms that renders clear interpretations difficult, and theories that largely test against null hypotheses. We suggest that these challenges present several opportunities for new research and we encourage the field to abandon simplistic dichotomies and connect much more with existing research programmes such as semantics, memory and attention, which have all built diverse research platforms over many decades and that can help shape how social modulation is conceptualised and studied from a cognitive and brain perspective. We also outline ways that stronger theoretical positions can be taken, which avoid comparing to null hypotheses, and endorse methodological reform through fully embracing proposals from the open science movement and "credibility revolution". We feel that by taking these opportunities, the field will have a better chance of reaching its potential to build a cumulative science of social modulation that can inform understanding of basic cognitive and brain systems, as well as real-life social interactions and the varied abilities observed across the Autism Spectrum.

fMRI repetition suppression reveals no sensitivity to trait judgments from faces in face perception or theory-of-mind networks.

The human face cues a wealth of social information, but the neural mechanisms that underpin social attributions from faces are not well known. In the current fMRI experiment, we used repetition suppression to test the hypothesis that populations of neurons in face perception and theory-of-mind neural networks would show sensitivity to faces that cue distinct trait judgments. Although faces were accurately discriminated based on associated traits, our results showed no evidence that face or theory-of-mind networks showed repetition suppression for face traits. Thus, we do not provide evidence for population coding models of face perception that include sensitivity to high and low trait features. Due to aspects of the experimental design, which bolstered statistical power and sensitivity, we have reasonable confidence that we could detect effects of a moderate size, should they exist. The null findings reported here, therefore, add value to models of neural organisation in social perception by showing instances where effects are absent or small. To test the generalisability of our findings, future work should test different types of trait judgment and different types of facial stimuli, in order to further probe the neurobiological bases of impression formation based on facial appearance.

A practical and flexible implementation of 3D MRI in the Earth's magnetic field.

The Earth's magnetic field, though weak, is appealing for NMR applications because it is highly homogeneous, globally available and free. However, the practicality of Earth's field NMR (EFNMR) has long been limited by the need to perform experiments in outdoor locations where the local field homogeneity is not disrupted by ferrous or magnetic objects and where ultra-low frequency (ULF) noise sources are at a minimum. Herein we present a flexible and practical implementation of MRI in the Earth's magnetic field that demonstrates that EFNMR is not as difficult as it was previously thought to be. In this implementation, pre-polarization and ULF noise shielding, achieved using a crude electromagnet, are used to significantly improve signal-to-noise ratio (SNR) even in relatively noisy environments. A three axis gradient coil set, in addition to providing imaging gradients, is used to provide first-order shims such that sub-hertz linewidths can routinely be achieved, even in locations of significant local field inhomogeneity such as indoor scientific laboratories. Temporal fluctuations in the magnitude of the Earth's magnetic field are measured and a regime found within which these variations in Larmor frequency produce no observable artefacts in reconstructed images.

Incorporating variations in pesticide catabolic activity into a GIS-based groundwater risk assessment.

The catabolic activity of incumbent microorganisms in soil samples of eleven dissimilar soil series was investigated, with respect to the herbicide isoproturon. Soils were collected from a 30x37 km area of river catchment to the north-west of London, England. Catabolic activity in each soil type during a 500 h assay was determined by 14C-radiorespirometry. Results showed four soils that exhibited high levels of catabolic activity (33-44% mineralisation) while the remaining seven soils showed lower levels of catabolic activity (12-16% mineralisation). There was evidence to suggest that soils exhibiting high catabolic activity had low (<22%) clay content and tended towards lower organic carbon content (<2.7%), but that these higher levels of catabolic activity were also related to pre-exposure to isoproturon. The 14C-radiorespirometric results were used to produce a GIS layer representing levels of catabolic activity for the dissimilar soils across the study area. This layer was combined with other GIS layers relating to pesticide attenuation, including soil organic carbon content, depth to groundwater and hydrogeology, to produce a map showing risk of groundwater contamination by isoproturon. The output from this approach was compared with output from an attenuation-only approach and differences appraised. Inclusion of the catabolism layer resulted in a lowering of risk in the model in 15% of the study area. Although there appears to be limited benefit in including pesticide catabolic activity in this regional-scale groundwater risk model, this type of addition could be useful in a site-specific risk assessment.

Drug release from HPMC matrices in milk and fat-rich emulsions.

"Biorelevant" media for the fed stomach, including fat emulsions, are routinely used during in vitro testing of solid dosage forms. However, their complexity undoubtedly creates difficulties in identifying factors which affect drug release. Here, we show fats can directly influence drug release from hydroxypropyl methylcellulose (HPMC; Methocel K4M) matrices which are often subjected to biorelevant testing. Model fat systems included milk (0.1%-3.5% fat) and the parenteral emulsion Intralipid® (20%-30% fat). The matrix showed good extended-release properties for at least 12 h in these media (USP-1/USP-4), but at the highest fat concentration, release was retarded and shifted towards zero-order release. Confocal imaging studies using a water-soluble (fluorescein) and fat-soluble (Nile red) fluorophore provided evidence of phase separation of Intralipid® at the surface of the emerging gel. Combined magnetic resonance imaging-USP-4 drug release testing provided further evidence for deposition of fat on the tablets. We propose that the aqueous portion of the emulsion is removed by the hydrating matrix, causing coalescence and deposition of a fat layer at the surface, and these deposits cause slower drug release by reducing the matrix surface area available for release. Therefore, there is a risk of a direct interaction between fat emulsions and HPMC tablets, with resultant effects on drug release in vitro.

Report on EU guidance on groundwater monitoring developed under the common implementation strategy of the water framework directive.

The establishment of high quality long-term monitoring programmes is essential if the implementation of the Water Framework Directive (WFD) is to be effective. It is recognised that monitoring can be very expensive and so guidance is needed to establish cost-effective, risk-based and targeted groundwater monitoring across Europe that enables WFD objectives to be met. In this context, the Groundwater Working Group (WGC) of the Common Implementation Strategy (CIS) of the WFD has developed recommendations aiming to implement consistent groundwater monitoring across Europe. This has been published on the internet in the form of a non-legally binding guidance document, which provides useful elements for the development and maintenance of networks at high standards and thereby provide the necessary information to assess (ground)water status, identify trends in pollutant concentrations, support establishment and assessment of programmes of measures and the effective targeting of economic resources. This paper presents this guidance document.