Film dynamics and lubricant depletion by droplets moving on lubricated surfaces

Lubricated surfaces have shown promise in numerous applications where impinging foreign droplets must be removed easily; however, before they can be widely adopted, the problem of lubricant depletion, which eventually leads to decreased performance, must be solved. Despite recent progress, a quantitative mechanistic explanation for lubricant depletion is still lacking. Here, we first explained the shape of a droplet on a lubricated surface by balancing the Laplace pressures across interfaces. We then showed that the lubricant film thicknesses beneath, behind, and wrapping around a moving droplet change dynamically with droplet's speed---analogous to the classical Landau-Levich-Derjaguin problem. The interconnected lubricant dynamics results in the growth of the wetting ridge around the droplet, which is the dominant source of lubricant depletion. We then developed an analytic expression for the maximum amount of lubricant that can be depleted by a single droplet. Counter-intuitively, faster moving droplets subjected to higher driving forces deplete less lubricant than their slower moving counterparts. The insights developed in this work will inform future work and the design of longer-lasting lubricated surfaces

The Maxwell effect for polymer solutions at larger velocity gradients

The orientation angle and birefringence were found to run asymptotically in the case of rigid, anisotropic particle solutions (macromolecules) at larger flow gradients (the model examined is that of a two-dimensional flow of particles). The applicability of the produced formulae and the possibilities of using them to determine the particle dimensions have been established. The formulae indicate a monotony of the theoretical curves between the angle of orientation and the birefringence at larger flow gradients. The found analytical expressions are compared with the results of computing the orientation angle. © 1981

Bacteria Pattern Spontaneously on Periodic Nanostructure Arrays

Surface-associated bacteria typically form self-organizing communities called biofilms. Spatial segregation is important for various bacterial processes associated with cellular and community development. Here, we demonstrate bacterial ordering and oriented attachment on the single-cell level induced by nanometer-scale periodic surface features. These surfaces cause spontaneous and distinct patterning phases, depending on their periodicity, which is observed for several strains, both gram positive and negative. This patterning is a general phenomenon that can control natural biofilm organization.Chemistry and Chemical BiologyEngineering and Applied Science

Absorption and luminescence spectra of Pr3+ in CaWO4 monocrystals

A complete diagram of the Stark sublevels of Pr3+ for the P0,1;1D2;3F2,3 terms has been constructed on the basis of a study of the absorption and luminescence spectra of CaWO4 crystals containing Pr3+. Strong splitting of the Pr3+ terms in the environment examined has been established. © 1969 The Faraday Press, Inc

Complementary Control of Sensory Adaptation by Two Types of Cortical Interneurons

Reliably detecting unexpected sounds is important for environmental awareness and survival. By selectively reducing responses to frequently, but not rarely, occurring sounds, auditory cortical neurons are thought to enhance the brain\u27s ability to detect unexpected events through stimulus-specific adaptation (SSA). The majority of neurons in the primary auditory cortex exhibit SSA, yet little is known about the underlying cortical circuits. We found that two types of cortical interneurons differentially amplify SSA in putative excitatory neurons. Parvalbumin-positive interneurons (PVs) amplify SSA by providing non-specific inhibition: optogenetic suppression of PVs led to an equal increase in responses to frequent and rare tones. In contrast, somatostatin-positive interneurons (SOMs) selectively reduce excitatory responses to frequent tones: suppression of SOMs led to an increase in responses to frequent, but not to rare tones. A mutually coupled excitatory-inhibitory network model accounts for distinct mechanisms by which cortical inhibitory neurons enhance the brain\u27s sensitivity to unexpected sounds

A kinetic model of the transformation of a micropatterned amorphous precursor into a porous single crystal

Biogenic single crystals with complex shapes are believed to be generated by the crystallisation of an amorphous precursor. Recent biomimetic experiments on the crystallisation of calcite via amorphous-to-crystalline transition point to the fact that the transformation kinetics may be controlled by the micropattern and the macroscopic shape of the amorphous precursor phase. Here we analyse a simple kinetic model, based on thermodynamic considerations, showing that the presence of cavities in the micropatterned precursor phase might interfere with the transformation process and control its kinetics. The size of the cavities couples to the total surface energy and, hence, to crystal nucleation and growth, while the spacing of the cavities, as compared to the typical diffusion path, controls the possible nucleation of competing crystals.Chemistry and Chemical Biolog

Protein Synthesis-Dependent Associative Long-Term Memory in Larval Zebrafish

The larval zebrafish is a model organism to study the neural circuitry underlying behavior. There exist, however, few examples of robust long-term memory. Here we describe a simple, unrestrained associative place-conditioning paradigm. We show that visual access to a group of conspecifics has rewarding properties for 6- to 8-day-old larval zebrafish. We use this social reward as an unconditioned stimulus and pair it with a distinct visual environment. After training, larvae exhibited spatial preference for the location previously paired with the social reward for up to 36 h, indicating that zebrafish larvae can exhibit long-term associative memory. Furthermore, incubation with a protein synthesis inhibitor or an NMDAR-antagonist impaired memory. In future experiments, this learning paradigm could be used to study the social interactions of larval zebrafish or paired with cell-specific metabolic labeling to visualize circuits underlying memory formation

Probe method and a Carleman function

A Carleman function is a special fundamental solution with a large parameter for the Laplace operator and gives a formula to calculate the value of the solution of the Cauchy problem in a domain for the Laplace equation. The probe method applied to an inverse boundary value problem for the Laplace equation in a bounded domain is based on the existence of a special sequence of harmonic functions which is called a {\it needle sequence}. The needle sequence blows up on a special curve which connects a given point inside the domain with a point on the boundary of the domain and is convergent locally outside the curve. The sequence yields a reconstruction formula of unknown discontinuity, such as cavity, inclusion in a given medium from the Dirichlet-to-Neumann map. In this paper, an explicit needle sequence in {\it three dimensions} is given in a closed form. It is an application of a Carleman function introduced by Yarmukhamedov. Furthermore, an explicit needle sequence in the probe method applied to the reduction of inverse obstacle scattering problems with an {\it arbitrary} fixed wave number to inverse boundary value problems for the Helmholtz equation is also given.Comment: 2 figures, final versio

Directional wetting in anisotropic inverse opals

Porous materials display interesting transport phenomena due to the restricted motion of fluids within the nano- to micro-scale voids. Here, we investigate how liquid wetting in highly ordered inverse opals is affected by anisotropy in pore geometry. We compare samples with different degrees of pore asphericity and find different wetting patterns depending on the pore shape. Highly anisotropic structures are infiltrated more easily than their isotropic counterparts. Further, the wetting of anisotropic inverse opals is directional, with liquids filling from the side more easily. This effect is supported by percolation simulations as well as direct observations of wetting using time-resolved optical microscopy

Management of bipolar disorder in the intercontinental region: an international, multicenter, non-interventional, cross-sectional study in real-life conditions

Most of the existing data on real-life management of bipolar disorder are from studies conducted in western countries (mostly United States and Europe). This multinational, observational cohort study aimed to describe the management and clinical outcomes of bipolar patients in real-life conditions across various intercontinental countries (Bangladesh, Egypt, Iran, Israel, Tunisia, and Ukraine). Data on socio-demographic and disease characteristics, current symptomatology, and pharmacological treatment were collected. Comparisons between groups were performed using standard statistical tests. Overall, 1180 patients were included. The median time from initial diagnosis was 80 months. Major depressive disorder was the most common initial diagnosis. Mood stabilizers and antipsychotics were the most common drugs being prescribed at the time of the study. Antidepressants (mainly selective serotonin uptake inhibitors [SSRIs]) were administered to 36.1% of patients. Patients with bipolar I disorder received higher number of antipsychotics and anxiolytics than those with bipolar II disorder (p < 0.001). Presence of depressive symptoms was associated with an increase in antidepressant use (p < 0.001). Bipolar disorder real-life management practice, irrespective of region, shows a delay in diagnosis and an overuse of antidepressants. Clinical decision-making appears to be based on a multidimensional approach related to current symptomatology and type of bipolar disorder