We report the first application of 39K solid-state NMR to the study of tecto- and phyllosilicates. Under high field (11.7 Tesla) and with the application of a spin-echo sequence, informative 39K spectra can be obtained for several compounds of interest to the geologist and the agronomist. Tectosilicates and phyllosilicates can be distinguished from the uncorrected frequency (δCG) of the observed NMR peak. A series of montmorillonites submitted to increasing numbers of wetting and drying cycles was studied in order to discriminate between mobile and “fixed” forms of K+: when the spectra are run on hydrated samples, two different signals are observed corresponding to K+ in different hydration states, and NMR data can be correlated with the amount of exchangeable K+ measured by ion exchange. Thus, it appears that NMR can provide useful information on K fixation complementary to classical chemical methods.

This investigation characterises the time response and the transient turbulence dynamics undergone by rapidly decelerating turbulent pipe flows. A series of direct numerical simulations of decelerating flows between two steady Reynolds numbers were conducted for this purpose. The statistical analyses reveal that rapidly decelerating turbulent flows undergo four coherent, unambiguous transitional stages: inertial (stage I), a dramatic change of sign in the viscous force associated with the decay of the viscous shear stress at the wall together with a mild turbulence decay in the viscous sublayer; friction recovery (stage II), a recovery in viscous force and progressive decay in the turbulent inertia at the near-wall region; turbulence decay (stage III), a balanced decay in both turbulent inertia and viscous force at the near-wall and overlap regions; core relaxation (stage IV), slow turbulence decay at the core region. The FIK identity derived by Fukagata, Iwamoto and Kasagi (Phys. Fluids, vol. 14, 2002, L73–L76) was used to understand further how the flow dynamics influence the time response of the skin friction coefficient ($C_f$). The results show that although $C_f$ plateaus during the fourth stage, the turbulent contribution keeps decaying, undershoots and finally recovers to attain its final steady value. The time evolution of the azimuthal vorticity ($\omega _\theta$) flux reveals that as the flow is decelerated, a layer of negative $\omega _\theta$ is produced at the wall during the flow excursion. As time progresses, this negative vorticity propagates in the wall-normal direction, attenuating the pre-existing vorticity and producing a decay in the turbulence levels.

The repeated return of tetrapods to aquatic life provides some of the best-known examples of convergent evolution. One comparison that has received relatively little focus is that of mosasaurids (a group of Late Cretaceous squamates) and archaic cetaceans (the ancestors of modern whales and dolphins), both of which show high levels of craniodental disparity, similar initial trends in locomotory evolution, and global distributions. Here we investigate convergence in skull ecomorphology during the initial aquatic radiations of these groups. A series of functionally informative ratios were calculated from 38 species, with ordination techniques used to reconstruct patterns of functional ecomorphospace occupation. The earliest fully aquatic members of each clade occupied different regions of ecomorphospace, with basilosaurids and early russellosaurines exhibiting marked differences in cranial functional morphology. Subsequent ecomorphological trajectories notably diverge: mosasaurids radiated across ecomorphospace with no clear pattern and numerous reversals, whereas cetaceans notably evolved toward shallower, more elongated snouts, perhaps as an adaptation for capturing smaller prey. Incomplete convergence between the two groups is present among megapredatory and longirostrine forms, suggesting stronger selection on cranial function in these two ecomorphologies. Our study highlights both the similarities and divergences in craniodental evolutionary trajectories between archaic cetaceans and mosasaurids, with convergences transcending their deeply divergent phylogenetic affinities.

We replicate a design ideation experiment (Goucher-Lambert et al., 2019) with and without inspirational stimuli and extend data collection sources to eye-tracking and a think aloud protocol to provide new insights into generated ideas. Preliminary results corroborate original findings: inspirational stimuli have an effect on idea output and questionnaire ratings. Near and far inspirational stimuli increased participants’ idea fluency over time and were rated more useful than control. We further enable experiment reproducibility and provide publicly available data.

This study examines the precursors and consequences of rare backflow events at the wall using direct numerical simulation of turbulent pipe flow with a high spatiotemporal resolution. The results obtained from conditionally averaged fields reveal that the precursor of a backflow event is the asymmetric collision between a high- and a low-speed streak (LSS) associated with the sinuous mode of the streaks. As the collision occurs, a lifted shear layer with high local azimuthal enstrophy is formed at the trailing end of the LSS. Subsequently, a spanwise or an oblique vortex spontaneously arises. The dominant nonlinear mechanism by which this vortex is engendered is enstrophy intensification due to direct stretching of the lifted vorticity lines in the azimuthal direction. As time progresses, this vortex tilts and orientates towards the streamwise direction and, as its enstrophy increases, it induces the breakdown of the LSS located below it. Subsequently, this vortical structure advects as a quasi-streamwise vortex, as it tilts and stretches with time. As a result, it is shown that reverse flow events at the wall are the signature of the nonlinear mechanism of the self-sustaining process occurring at the near-wall region. Additionally, each backflow event has been tracked in space and time, showing that approximately 50 % of these events are followed by at least one additional vortex generation that gives rise to new backflow events. It is also found that up to a maximum of seven regenerations occur after a backflow event has appeared for the first time.

The transient dynamics of accelerating turbulent pipe flow has been examined using direct numerical simulation (DNS) data sets with a high spatiotemporal resolution, starting from low and moderate Reynolds numbers. The time-dependent evolution of the mean flow dynamics reveals that internal flows, during and after a rapid increase in the flow rate, experience four unambiguous transient stages: inertial, pre-transition, transition and core relaxation before they reach their final steady-state. The first stage is characterised by a rapid and substantial increment in the viscous forces within the viscous sublayer, together with the frozen behaviour of the existing turbulent eddies. The pre-transitional stage reveals a weak response of the turbulent inertia within the near-wall region, together with a rapid reduction in the viscous forces. At the third stage, termed transition, balanced growth in the magnitude of both the turbulent and the viscous forces within $y^{+0} \lesssim 50$ is observed. The final stage, referred to as core relaxation, shows a quasi-steady behaviour at $y^{+0} < 50$ and reveals the slow propagation of turbulence from the near-wall region into the wake region. A decomposition of the skin friction coefficient ($C_f$), using an FIK identity suitable for unsteady pipe flow, shows a progressive increment in the turbulent contribution during the core-relaxation period. Simultaneously, the unsteady contribution decreases proportionally, maintaining a plateau in $C_f$. The principal mechanism responsible for this slow regeneration in the wake is a temporal turbulence stratification at the inner region of the flow, together with a quiescent core, which maintains geometric coherence across extensive periods.

In the fields of microgripping and microassembly, the self-alignment motion of a solid micro-object linked by a liquid meniscus to a substrate or a tool is an inexpensive way to overcome the current limitations of the assembly processes at microscale by getting rid of the positioning actuators. Original models providing a dynamical description of the capillary self-alignment of an $L\times D \times d$ chip are reported, as well as experimental results as evidence of their validity. The first two models describe the liquid and the solid physics in two dimensions. Both include nonlinearities and describe the coupling between a laminar flow and a solid structure. The fluid–solid coupling is ensured by the boundary conditions at their surface of contact and by the forces the liquid and the solid apply on each other. Both models yield the shift, lift and tilt modes of deformation of the liquid meniscus. Equations are first numerically solved by using a finite element method (model 1). By approximating the menisci with spherical caps, a geometrical model is then presented (model 2). Next, for small oscillations and thin liquid layers, the equations are linearised. The solution to the semianalytical three degrees of freedom (3-DOF) modal analysis is thus obtained (model 3). Finally, a semianalytical 1-DOF model is presented and numerically solved by considering a one-dimensional motion for the solid object (model 4). Solutions for models 1, 3 and 4 are computed and show good agreement with the experimental measurements. Yet, the remaining deviations are investigated to identify their origin.

This work presents a detailed analysis of the flow structures relevant to extreme wall shear stress events for turbulent pipe flow direct numerical simulation data at a friction Reynolds number $\textit {Re}_{\tau} \approx 1000$. The results reveal that extreme positive wall-friction events are located below an intense sweep (Q4) event originated from a strong quasi-streamwise vortex at the buffer region. This vortex transports high streamwise momentum from the overlap and the outer layers towards the wall, giving rise to a high-speed streak within the inner region. This vortical structure also relates to regions with extreme wall-normal velocity. Consequently, the conditional fields of turbulence production and viscous dissipation exhibit peaks whose magnitudes are approximately 25 times higher than the ensemble mean quantities in the vicinity of the extreme positive events. An analysis of the turbulent inertia force reveals that the energetic quasi-streamwise vortex acts as an essential source of momentum at the near-wall region. Similarly, extremely rare backflow events are studied. An examination of the wall-normal vorticity and velocity vector fields shows an identifiable oblique vortical structure along with two other large-scale roll modes. These counter-rotating motions contribute to the formation of backflow events by transporting streamwise momentum from the inner to the outer region, creating a large-scale meandering low-speed streak. It is found that extreme events are clustered below large-scale structures of positive streamwise momentum that interact with near-wall low-speed streaks, related to regions densely populated with vortical structures. Finally, a three-dimensional model is proposed to conceptualise the flow dynamics associated with extreme events.

Complex organic molecules (COMs) have been detected in the gas-phase in cold and lightless molecular cores. Recent solid-state laboratory experiments have provided strong evidence that COMs can be formed on icy grains through ‘non-energetic’ processes. In this contribution, we show that propanal and 1-propanol can be formed in this way at the low temperature of 10 K. Propanal has already been detected in space. 1-propanol is an astrobiologically relevant molecule, as it is a primary alcohol, and has not been astronomically detected. Propanal is the major product formed in the C2H2 + CO + H experiment, and 1-propanol is detected in the subsequent propanal + H experiment. ALMA observations towards IRAS 16293-2422B are discussed and provide a 1-propanol:propanal upper limit of < 0.35–0.55, which are complemented by computationally-derived activation barriers in addition to the performed laboratory experiments.

OBJECTIVES/SPECIFIC AIMS: Our primary objective was to understand the relationship between incident or recent stressful events and adherence to HIV care in the context of other person, environment, and HIV-specific stressors in a sample of Black women living with HIV (WLWH). METHODS/STUDY POPULATION: Thirty in-depth interviews were conducted with Black women living with HIV who receive care at an academic HIV primary care clinic in the Southern region of the United States to elicit stressful events influencing adherence to HIV care. Semi-structured interview guides were used to facilitate discussion regarding stressful events and adherence to HIV care. Interviews were audiotaped and transcribed verbatim. Transcripts were independently coded using a theme-based approach by two experienced coders, findings were compared, and discrepancies were resolved by discussion. RESULTS/ANTICIPATED RESULTS: Participants described frequently experiencing incident stressful events including death or serious illness of a close friend or family member, and relationship, financial, and employment difficulties. Furthermore, participants reported experiencing traumatic events such as sexual and physical abuse during childhood and adolescents. While experiencing traumatic events such as sexual and physical abuse during childhood and adolescence may be distressing, these events did not influence adherence to HIV care. However, incident stressful events as defined above did influence adherence to HIV care for some participants, but not for others. For participants who reported that stressful events did not influence adherence to HIV care, factors such as personal motivation, access to social support, and adaptive coping strategies facilitated their engagement in care. DISCUSSION/SIGNIFICANCE OF IMPACT: Experiencing stressful events, incident or traumatic, is common among Black WLWH and have the potential to negatively influence adherence to HIV care. Thus, Interventions aimed at identifying and addressing stress, social support, and coping are essential to improve adherence to HIV care behaviors.

Sediments of the Tertiary Akata and Agbada Formations have been studied by mineralogical and petrographic techniques. In the Akata and Agbada shales the clays are largely detrital, with only minimal alteration attributable to the effects of burial diagenesis. Clay minerals occur in minor (<10%) amounts in the reservoir sandstones of the Agbada Formation both as detrital and authigenic phases. There are significant differences between the clay assemblages of the water- and hydrocarbon-bearing sandstones. The latter have lower overall clay contents and authigenic kaolinite, whilst authigenic kaolinite and smectite are present in the water-saturated sandstones. These differences are thought to be related to the early migration of hydrocarbons into the reservoir sands. The causes of the poor degree of cementation in the Agbada sandstones are discussed along with the engineering problems posed by their very friable nature.

Microprobe analyses of members of the erlichmanite-laurite series from Guma Water and Senduma, Sierra Leone and Tanah Laut, Borneo, indicate that complete solid solution is possible between OsS2 and RuS2 with considerable substitution of Os and Ru by Ir, Rh, and Pt. The cell size of the erlichmanite from Guma Water is a = 5.6183±0.0003 Å at a composition (Os0.61Ru0.30Ir0.06Rh0.03)Σ0.93S2 whilst the laurite from Senduma has a composition of (Ru0.88Os0.05Ir0.04 Rh0.03)Σ0.93S2 and a cell size of a = 5.6089±0.0005 Å. Substitution of Os for Ru provides the predominant cause of the variation of cell size. Substitution by other elements of the platinum group appears to produce little effect on cell size and is presumably controlled by genesis rather than considerations of crystal chemistry or structure. The recorded analyses for these elements indicate a pre-dominance of Ir over Rh for members of the series containing more than about 15% of the laurite molecule. For the remainder of the series Rh is more important than Ir. The reflectance in air and oil of the members of the series from Sierra Leone and Borneo are presented and the microhardness of the erlichmanite from Guma Water shown to be 1854 kg/mm2. This is the first report of laurite from Senduma, Sierra Leone.

We performed a spatial-temporal analysis to assess household risk factors for Ebola virus disease (Ebola) in a remote, severely-affected village. We defined a household as a family's shared living space and a case-household as a household with at least one resident who became a suspect, probable, or confirmed Ebola case from 1 August 2014 to 10 October 2014. We used Geographic Information System (GIS) software to calculate inter-household distances, performed space-time cluster analyses, and developed Generalized Estimating Equations (GEE). Village X consisted of 64 households; 42% of households became case-households over the observation period. Two significant space-time clusters occurred among households in the village; temporal effects outweighed spatial effects. GEE demonstrated that the odds of becoming a case-household increased by 4·0% for each additional person per household (P < 0·02) and 2·6% per day (P < 0·07). An increasing number of persons per household, and to a lesser extent, the passage of time after onset of the outbreak were risk factors for household Ebola acquisition, emphasizing the importance of prompt public health interventions that prioritize the most populated households. Using GIS with GEE can reveal complex spatial-temporal risk factors, which can inform prioritization of response activities in future outbreaks.

This research explored sex differences in the pathways linking pubertal timing to depression across 4 years. A sample of 167 youth (M age = 12.41 years, SD = 1.19) and their caregivers completed measures of puberty and semistructured interviews of interpersonal stress and youth depression. Youth reported on psychological (negative self-focus, anxious arousal) and social–behavioral (coping) characteristics; parents reported on youths’ social–behavioral characteristics (withdrawal/social problems) and deviant peer affiliations. Early maturation predicted stable high trajectories of depression in girls; although early maturing boys showed low initial levels of depression, they did not differ from girls by the final wave of the study. Latent growth curve analyses identified several psychological, social–behavioral, and interpersonal pathways accounting for the contribution of pubertal timing to initial and enduring risk for depression in girls as well as emerging risk for depression in boys. These findings provide novel insight into multilevel processes accounting for sex differences in depression across the adolescent transition.

Many African American adolescents experience racial discrimination, with adverse consequences; however, stability and change in these experiences over time have not been examined. We examined longitudinal patterns of perceived racial discrimination assessed in Grades 7–10 and how these discrimination trajectories related to patterns of change in depressive and anxious symptoms and aggressive behaviors assessed over the same 4-year period. Growth mixture modeling performed on a community epidemiologically defined sample of urban African American adolescents (n = 504) revealed three trajectories of discrimination: increasing, decreasing, and stable low. As predicted, African American boys were more frequent targets for racial discrimination as they aged, and they were more likely to be in the increasing group. The results of parallel process growth mixture modeling revealed that youth in the increasing racial discrimination group were four times more likely to be in an increasing depression trajectory than were youth in the low stable discrimination trajectory. Though youth in the increasing racial discrimination group were nearly twice as likely to be in the high aggression trajectory, results were not statistically significant. These results indicate an association between variation in the growth of perceived racial discrimination and youth behavior and psychological well-being over the adolescent years.

This paper compares the dynamics of two local pig breeds (the Porc Blanc de l'Ouest and the Nustrale pig breeds). Those breeds are bred in contrasting territories and we demonstrate by our comparative analysis the diversity of visible stakes in the link of breeds to territories. We distinguish three categories of dissimilarities between the two cases: the first is linked to biogeographic dimension of the territory, the second to the agro-economic dimension of the territory and the last to the sociocultural aspects of the territory. We develop in the discussion an invitation to pay more attention to anchorage dynamics of local breeds in their territories.