Geometry-induced phase transition in fluids: capillary prewetting

We report a new first-order phase transition preceding capillary condensation and corresponding to the discontinuous formation of a curved liquid meniscus. Using a mean-field microscopic approach based on the density functional theory we compute the complete phase diagram of a prototypical two-dimensional system exhibiting capillary condensation, namely that of a fluid with long-ranged dispersion intermolecular forces which is spatially confined by a substrate forming a semi-infinite rectangular pore exerting long-ranged dispersion forces on the fluid. In the T-mu plane the phase line of the new transition is tangential to the capillary condensation line at the capillary wetting temperature, Tcw. The surface phase behavior of the system maps to planar wetting with the phase line of the new transition, termed capillary prewetting, mapping to the planar prewetting line. If capillary condensation is approached isothermally with T>Tcw, the meniscus forms at the capping wall and unbinds continuously, making capillary condensation a second-order phenomenon. We compute the corresponding critical exponent for the divergence of adsorption.Comment: 5 pages, 4 figures, 5 movie

Traumatic brain injury: Age at injury influences dementia risk after TBI

Traumatic brain injury (TBI) is increasingly recognized as a risk factor for dementia. New data provide further support for this association and demonstrate the influence of age at injury and injury severity on dementia risk after TBI, revealing that even mild TBI increases dementia risk in those aged ≥65 years

Structure of a bacterial type IV secretion core complex at subnanometre resolution

Type IV secretion (T4S) systems are able to transport DNAs and/or proteins through the membranes of bacteria. They form large multiprotein complexes consisting of 12 proteins termed VirB1-11 and VirD4. VirB7, 9 and 10 assemble into a 1.07 MegaDalton membrane-spanning core complex (CC), around which all other components assemble. This complex is made of two parts, the O-layer inserted in the outer membrane and the I-layer inserted in the inner membrane. While the structure of the O-layer has been solved by X-ray crystallography, there is no detailed structural information on the I-layer. Using high-resolution cryo-electron microscopy and molecular modelling combined with biochemical approaches, we determined the I-layer structure and located its various components in the electron density. Our results provide new structural insights on the CC, from which the essential features of T4S system mechanisms can be derived

Screening and quantification of micro(nano)plastics and plastic additives in the seawater of Mar Menor lagoon

In this work a suspect-screening approach was employed to assess the polymers and plastic additives of micro(nano)plastics (NPL/MPLs) of size ranges from the nm range to 20 μm present in seawater from the top 5 cm of the Mar Menor lagoon during two sampling campaigns (summer and winter), as well of other potentially adsorbed compounds onto the plastic particles surfaces and suspended material. The identification of NPL/MPLs has been based on characteristic Kendrick Mass Defect analysis for each polymer type in mass spectra. The applied methodology allowed to identify NPLs/MPLs of polystyrene (PS), polyethylene (PE), polyisoprene (PI), polybutadiene (PBD), polypropylene (PP), polyamides (PA), polyvinylchloride (PVC), n-isopropylacrylamide (PNIPAm), and polydimethylsiloxanes. In addition, PS, PE, PI, PBD, PP, PA, and PVC were confirmed with standards, and the equivalent concentrations were quantified. The results of this study showed that most frequently found compounds were PP, PE, PA and PNIPAm, while the compound found at higher concentrations was by far PP reaching the 9,303 ± 366 ng/mL in one of the samples. A total number of 135 chemical compounds were tentatively identified, 74 of them plastic additives and compounds used in the polymers manufacture or coming from the polymer’s decomposition. In relation to plastic additives, the more frequently tentatively identified compounds were plasticizers such as phthalates group; stabilizers such as antioxidants (e.g., distearyl 3,3′-thiodipropionate, 2,5-di-tert-butylhydroquinone), and UV filters as benzotriazoles. Several flame retardants of the group of phosphates were as well detected. The other compounds tentatively identified in the samples were pharmaceuticals, pesticides, food additives, flavors and natural products that were attached onto the plastic particles and particulate matter from surrounding waters. In regards to the seasonal variation, during the summer a major number of compounds were tentatively detected, while de concentrations of polymers were slightly higher in winter. The spatial distribution showed higher contamination in the southern part of the coastal lagoon.Postprin

Generalized dynamical density functional theory for classical fluids and the significance of inertia and hydrodynamic interactions

We study the dynamics of a colloidal fluid including inertia and hydrodynamic interactions, two effects which strongly influence the non-equilibrium properties of the system. We derive a general dynamical density functional theory (DDFT) which shows very good agreement with full Langevin dynamics. In suitable limits, we recover existing DDFTs and a Navier-Stokes-like equation with additional non-local terms.Comment: 5 pages, 4 figures, 4 supplementary movie files, I supplementary pd

A Gas Leak Rate Measurement System for the ATLAS MUON BIS-Monitored Drift Tubes

A low-cost, reliable and precise system developed for the gas leak rate measurement of the BIS-Monitored Drift Tubes (MDTs) for the ATLAS Muon Spectrometer is presented. In order to meet the BIS-MDT mass production rate, a total number of 100 tubes are tested simultaneously in this setup. The pressure drop of each one of the MDT is measured, within a typical time interval of 48 hours, via a differential manometer comparing with the pressure of a gas tight reference tube. The precision of the method implemented is based on the system temperature homogeneity, with accuracy of ÄT = 0.3 oC. For this reason, two thermally isolated boxes are used testing 50 tubes each of them, to achieve high degree of temperature uniformity and stability. After measuring several thousands of the MDTs, the developed system is confirmed to be appropriate within the specifications for testing the MDTs during the mass production

Response efficiency: Behavioural manifestations of an emotion-led subjective experience of duration

AbstractNumerous theories have been proposed on the influence of emotion on our perception of time, with recent work favouring attentional mechanisms as opposed to more traditional accounts of an ‘internal clock’ (Lui, Penney, & Schirmer, 2011). For example, the perceived duration of an emotional event may depend on both its behavioural relevance, as well as the stimulus-driven salience of its features (Lambrechts et al., 2011; Bradley & Lang, 2007; Noulhiane et al., 2007; Gil et al., 2007). In the same light, seminal work by Eagleman (2008) focused on subjective duration perception following short and automatic (as opposed to lengthier and more cognitively loaded) events. The literature however, lacks an account of observable differences in response efficiency (i.e., response time and accuracy), which may be related to changes in our perception of an emotional event's duration, specifically in relation to automatic emotionally loaded events. Drawing from behavioural findings from three studies investigating effects of facial emotion on response efficiency (which however do not explicitly measure subjective timing), this theoretical presentation attempts to recast our results from the above perspective of the proposed relation between attentional engagement and subjective duration.Our three experiments were originally designed to investigate rapid spatial attentional engagement to emotional stimuli. We measured the effects of the poser's eye-gaze, concurrent auditory threat, and participant's rated anxiety on the speed and accuracy of responses to facial emotion in three speeded forced-choice studies. In Study 1, 24 right-handed healthy adults viewed bilateral displays of a neutral face paired with either a fearful or angry face, and presented for 50ms; the task was to indicate the left-right location of the emotional face. Stimuli varied in intensity of facial expression, and gaze (left, right, ahead). Study 2 (N=23, all right-handed) increased stimulus exposure time to 100ms with added looming or receding sound unpredictably per trial, to test whether looming sounds selectively enhance emotional face detection. In Study 3 (N=24, all right-handed), participants viewed brief bilateral displays of angry or happy faces paired with their respective neutral expression, and also completed the State Anxiety sub-scale (Y-1) of the Spielberger State-Trait Anxiety Inventory.Gaze did not lead to a detection advantage for angry faces in Tasks 1 &2 regardless of stimulus exposure time or auditory threat unpredictability. Interestingly though, response efficiency was increased for both anger and fear, and further increased with the addition of looming sounds. Effects were found even for extremely subtle and ambiguous emotional expressions. In Task 3, we observed a speed-accuracy trade off in highly anxious participants particularly for ambiguous faces with emotional intensities near to threshold.By observing the modulation of response efficiency in displays of automatic and ambiguous emotional faces, we propose that these findings and previous results could be explained in terms of attentionally-driven changes in duration perception. Attention appears to modulate response efficiency depending on the emotional salience of a stimulus, with more of our attentional resources being needed when faced with an ambiguous emotional event. Even when considering responses from highly anxious participants, it appears as though it is not the specific nature of the event itself that shapes their responses, but the ambiguity of the stimuli they are presented with. It could therefore be the case that our subjective experience of duration of an emotional event is inherently linked with the level of reflex-like automaticity that the event itself presents. When our attention is ‘grabbed’ by a sudden exposure to an emotional stimulus, our consequently speeded and more efficient response might reflect a dilation of subjective time during response preparation – perhaps especially important when the event is pertaining to threat. Though the present data do not pertain directly to subjective timing, it is possible that the attentional demands posed on participants while deciphering the relevance of ambiguous emotional stimuli could have caused changes in duration perception of the kind previously reported to be associated with emotional stimuli. Our theoretical suggestion could therefore lead to future studies combining reaction times and accuracy with an explicit measure of duration perception