Abstract
This work provides evidence that anisotropic drainage in sheared foam is at the origin of convective instability in very long foam channels. Convective instability occurs in foam under ...forced drainage when a critical liquid fraction is exceeded. Liquid spontaneously accumulates at one side of the channel. The weight imbalance induces convection rolls in the foam. Experiments in a very long vertical foam channel demonstrate that the critical liquid fraction is smaller than in previous findings by a factor of five. The critical liquid fraction depends on both the channel length and the inhomogeneity of the liquid feed. Well below the critical liquid fraction, a static, elastic shear deformation of the foam structure occurs. At the critical liquid fraction, initial steady convection rolls are located at the lower region of the channel and expand as the liquid fraction further increases. Combining the drainage equation with both the elastic response of the foam and a model for anisotropic drainage, a critical liquid fraction for the growth of an initial liquid imbalance is derived analytically, which corresponds very well to experimental findings. Numerical simulations of the drainage equation and the elastic response of the foam reproduce these experimental and analytical findings.
The specific area of the solid-liquid interface of an assembly of dendrites is an important integral measure of the morphology of the microstructure forming during alloy solidification. It represents ...the inverse of a characteristic length scale and is needed for the prediction of solidification defects and material properties. In the present study, the evolution of the interfacial area of dendrites is analysed using 3D phase-field simulations. A general evolution equation is developed for the specific interface area as a function of time and solid volume fraction that accounts for the effects of growth, curvature-driven coarsening and interface coalescence. The relation is validated using data from previously performed synchrotron X-ray tomography and isothermal coarsening experiments. It is found to be valid for arbitrary and even varying cooling rates and for a wide range of binary alloys. The rate constant in the evolution equation is successfully related to alloy properties.
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Representing Italy Through Food Peter Naccarato, Zachary Nowak, Elgin K. Eckert / Peter Naccarato, Zachary Nowak, Elgin K. Eckert
2017, 2017-03-09
eBook
Italy has long been romanticized as an idyllic place. Italian food and foodways play an important part in this romanticization – from bountiful bowls of fresh pasta to bottles of Tuscan wine. While ...such images oversimplify the complex reality of modern Italy, they are central to how Italy is imagined by Italians and non-Italians alike. Representing Italy through Food is the first book to examine how these perceptions are constructed, sustained, promoted, and challenged. Recognizing the power of representations to construct reality, the book explores how Italian food and foodways are represented across the media – from literature to film and television, from cookbooks to social media, and from marketing campaigns to advertisements. Bringing together established scholars such as Massimo Montanari and Ken Albala with emerging scholars in the field, the thirteen chapters offer new perspectives on Italian food and culture. Featuring both local and global perspectives – which examine Italian food in the United States, Australia, and Israel – the book reveals the power of representations across historical, geographic, socio-economic, and cultural boundaries and asks if there is anything that makes Italy unique. An important contribution to our understanding of the enduring power of Italy, Italian culture, and Italian food – both in Italy and beyond. Essential reading for students and scholars in food studies, Italian studies, media studies, and cultural studies.
The local dynamics of dendritic sidearms during coarsening are studied by combining in-situ radiography observations with numerical and analytical models. A flat sample of a Ga-In alloy is partially ...solidified and then held isothermally in a vertical temperature gradient. The evolving dendritic microstructure is visualized using synchrotron X-ray imaging at the BM20 (ROBL) beamline at ESRF, France. During the coarsening stage, the temporal evolution of the geometrical features of sidebranches is captured by automated image processing. This data is then used to quantify the dynamics of two basic evolution mechanisms for sidebranches: retraction and pinch-off. The universal dynamics of sidearm necks during pinch-off are exploited to determine the product of liquid diffusivity and capillarity length Dd0, as a parameter that is crucial in the calibration of quantitative models. By employing an idealized phase-field model for the evolution of a single sidebranch, the behavior of selected sidebranches is reproduced from the experiments in a consistent way.
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The dynamics of hydrogen bubbles produced by water electrolysis in an acidic electrolyte is studied using electrochemical and optical methods. A defined cyclic modulation of the electric potential is ...applied at a microelectrode to produce pairs of interacting H$_2$ bubbles in a controlled manner. Three scenarios of interactions are identified and studied systematically. The most prominent one consists of a sudden reversal in the motion of the first detached bubble, its return to the electrode, and finally its coalescence with the second bubble. Attested by Toepler's schlieren technique, an explanation of contactless motion reversal is provided by the competition between buoyancy and thermocapillary effects.
The electrodeposition of copper on a conically shaped diamagnetic electrode was studied under the influence of a vertical magnetic field. Numerical simulations combined with measurements of the ...velocity and the concentration field were conducted to provide understanding of the influence of the Lorentz force on the deposition process. The secondary flow caused by the magnetic field is directed downward along the cone surface and thus supporting conical growth. Since the cathode is placed at the bottom of the electrochemical cell, natural convection is counteracting the influence of the Lorentz force. However, the different time scales of both forces involved allow utilizing the beneficial influence of the Lorentz force, e.g. in pulsed deposition regimes.
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•combined experimental and numerical study of the electrodeposition of copper at a conically shaped electrode•the single cone study is motivated as generic case of rough and regularly surface-structured electrodes•a vertical magnetic field is found to be beneficial for enhancing conical growth•the secondary flow induced by the Lorentz force increases the deposition rate near the cone tip•the influence of solutal buoyancy is strong and superimposing the magnetic field effect, but might be mitigated
Lipopolysaccharide (LPS) binding protein (LBP) is an acute-phase protein that initiates an immune response after recognition of bacterial LPS. Here, we report the crystal structure of murine LBP at ...2.9 Å resolution. Several structural differences were observed between LBP and the related bactericidal/permeability-increasing protein (BPI), and the LBP C-terminal domain contained a negatively charged groove and a hydrophobic “phenylalanine core.” A frequent human LBP SNP (allelic frequency 0.08) affected this region, potentially generating a proteinase cleavage site. The mutant protein had a reduced binding capacity for LPS and lipopeptides. SNP carriers displayed a reduced cytokine response after in vivo LPS exposure and lower cytokine concentrations in pneumonia. In a retrospective trial, the LBP SNP was associated with increased mortality rates during sepsis and pneumonia. Thus, the structural integrity of LBP may be crucial for fighting infections efficiently, and future patient stratification might help to develop better therapeutic strategies.
•Crystallographic study reveals the three-dimensional structure of LBP•Structural differences from BPI are key for LBP’s distinct function•A frequently occurring human LBP mutation strongly alters LBP function•Structural integrity of LBP is key for the course of infectious diseases in patients
•4D PTV was successfully applied to study bubble-particle attachment events.•Polystyrene particles are promising as model particles for fine particle flotation.•Limitations of existing collision ...probability models were revealed.•Particles with a low inertia collided at the rear surface of the bubble.
This work focuses on analysing the collection process in flotation by means of a simultaneous time-resolved measurement of particle and bubble trajectories. We introduced a new method that determined the probability of collision and attachment using a 3D particle-tracking method with high temporal resolution (1000 fps) and spatial (0.03 mm/pixel) resolution in a dense particle flow (5000 particles/ml). A 4D particle image tracking device with three high-speed cameras recorded the three-phase flow in a rectangular bubble column (2 mm, bubble chain). Particles made of fluorescent polystyrene were employed so that particles appeared bright and bubbles dark on the captured images. An attachment occurred if the trajectory of a particle coincided with that of a bubble. The recovery was calculated based on the number of particles attached to a bubble compared to the total number of particles within a reference volume. With this method, the true flotation depending on the particle diameter (30–100 μm) was investigated and the results compared with an existing model of the bubble-particle collection microprocess.
The S-layer proteins are a class of self-assembling proteins that form bi-dimensional lattices named S-Layer on the cell surface of bacteria and archaea. The protein SlpA, which is the major ...constituent of the
S-layer, contains in its C-terminus region (SlpA
), a protein domain (named here as SLAP
) responsible for the association of SlpA to the bacterial surface. SLAP
was adapted for the development of a novel affinity chromatography method: the SLAP
-based affinity chromatography (SAC).
Proteins with different molecular weights or biochemical functions were fused in-frame to the SLAP
and efficiently purified by a
-derived affinity matrix (named Bio-Matrix or BM). Different binding and elution conditions were evaluated to establish an optimized protocol.
The binding equilibrium between SLAP
and BM was reached after a few minutes of incubation at 4°C, with an apparent dissociation constant (K
) of 4.3μM. A reporter protein (H6-GFP-SLAP
) was used to compare SAC protein purification efficiency against commercial immobilized metal affinity chromatography. No differences in protein purification performance were observed between the two methods. The stability and reusability of the BM were evaluated, and it was found that the matrix remained stable for more than a year. BM could be reused up to five times without a significant loss in performance. Additionally, the recovery of bound SLAP-tagged proteins was explored using proteolysis with a SLAP-tagged version of the HRV-3c protease (SLAP
). This released the untagged GFP while the cut SLAP
and the SLAP
were retained in the BM. As an alternative, iron nanoparticles were linked to the BM, resulting in BM
. The BM
was successfully adapted for a magnetic SAC, a technique with potential applications in high-throughput protein production and purification.
The SAC protocol can be adapted as a universal tool for the purification of recombinant proteins. Furthermore, the SAC protocol utilizes simple and low-cost reagents, making it suitable for in-house protein purification systems in laboratories worldwide. This enables the production of pure recombinant proteins for research, diagnosis, and the food industry.
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