Multi-Armed Droplets as Shape-Changing Protocells

Protocells are objects that mimic one or several functions of biological cells and may be embodied as solid particles, lipid vesicles, or droplets. Our work is based on using decanol droplets in an aqueous solution of sodium decanoate in the presence of salt. A decanol droplet under such conditions bears many qualitative similarities with living cells, such as the ability to move chemotactically, divide and fuse, or change its shape. This article focuses on the description of a shape-changing process induced by the evaporation of water from the decanoate solution. Under these conditions, the droplets perform complex shape changes, whereby the originally round decanol droplets grow into branching patterns and mimic the growth of appendages in bacteria or axon growth of neuronal cells. We report two outcomes: (i) the morphological changes are reversible, and (ii) multiple protocells avoid contact between each other during the morphological transformation. The importance of these morphological changes in the context of artificial life are discussed.

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Effects of Aging on the Morphology of Rubber-Brass Interfacial Layer

Tire Science and Technology ◽

10.2346/1.3555084 ◽

2011 ◽

Vol 39 (1) ◽

pp. 20-43 ◽

Cited By ~ 7

Author(s):

A. Ashirgade ◽

P. B. Harakuni ◽

W. J. Vanooij

Keyword(s):

Chemical Composition ◽

Interfacial Layer ◽

Secondary Ion Mass Spectrometry ◽

Morphological Changes ◽

Grazing Incidence ◽

Complex Nature ◽

Rubber Compound ◽

Tire Cord ◽

Morphological Transformation ◽

Adhesion Promoter

Abstract Adhesion between rubber compound and brass-plated steel tire cord is crucial in governing the overall performance of tires. The rubber-brass interfacial adhesion is influenced by the chemical composition and thickness of the interfacial layer. It has been shown that the interfacial layer consists mainly of sulfides and oxides of copper and zinc. This paper discusses the effect of changes in the chemical composition and the structure of the interfacial layers due to addition of adhesion promoter resins. Grazing incidence x-ray diffraction (GIXRD) experiments were run on sulfidized polished brass coupons previously bonded to five experimental rubber compounds. It was confirmed that heat and humidity conditions lead to physical and chemical changes of the rubber-steel tire cord interfacial layer, closely related to the degree of rubber-brass adhesion. Morphological transformation of the interfacial layer led to loss of adhesion after aging. The adhesion promoter resins inhibit unfavorable morphological changes in the interfacial layer, thus stabilizing it during aging and prolonging failure. Tire cord adhesion tests illustrated that the one-component resins improved adhesion after aging using a rubber compound with lower cobalt loading. Based on the acquired diffraction profiles, these resins were also found to impede crystallization of the sulfide layer after aging, leading to improved adhesion. Secondary ion mass spectrometry depth profiles and scanning electron microscopy micrographs strongly corroborated the findings from GIXRD. This interfacial analysis adds valuable information to our understanding of the complex nature of the rubber-brass bonding mechanism.

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Selection for increased tibia length in mice alters skull shape through parallel changes in developmental mechanisms

10.1101/2020.10.01.321604 ◽

2020 ◽

Author(s):

Colton M. Unger ◽

Jay Devine ◽

Benedikt Hallgrímsson ◽

Campbell Rolian

Keyword(s):

Endochondral Ossification ◽

Morphological Changes ◽

Cranial Base ◽

Direct Selection ◽

Micro Ct ◽

Growth Plates ◽

History Of ◽

Selection For ◽

Tibia Length ◽

Shape Changes

AbstractBones in the vertebrate cranial base and limb skeleton grow by endochondral ossification, under the control of growth plates. Mechanisms of endochondral ossification are conserved across growth plates, which increases covariation in size and shape among bones, and in turn may lead to correlated changes in skeletal traits not under direct selection. We used micro-CT and geometric morphometrics to characterize shape changes in the cranium of the Longshanks mouse, which was selectively bred for longer tibiae. We show that Longshanks skulls became longer, flatter, and narrower in a stepwise process. Moreover, we show that these morphological changes likely resulted from developmental changes in the growth plates of the Longshanks cranial base, mirroring changes observed in its tibia. Thus, indirect and non-adaptive morphological changes can occur due to developmental overlap among distant skeletal elements, with important implications for interpreting the evolutionary history of vertebrate skeletal form.

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An asymmetric junctional mechanoresponse coordinates mitotic rounding with epithelial integrity

The Journal of Cell Biology ◽

10.1083/jcb.202001042 ◽

2021 ◽

Vol 220 (5) ◽

Author(s):

Jooske L. Monster ◽

Lisa Donker ◽

Marjolein J. Vliem ◽

Zaw Win ◽

Helen K. Matthews ◽

...

Keyword(s):

Epithelial Cells ◽

Morphological Changes ◽

Mitotic Cell ◽

Cell Junctions ◽

Actin Binding ◽

Epithelial Barrier ◽

Epithelial Integrity ◽

Tensile Forces ◽

Shape Changes ◽

Mitotic Cells

Epithelia are continuously self-renewed, but how epithelial integrity is maintained during the morphological changes that cells undergo in mitosis is not well understood. Here, we show that as epithelial cells round up when they enter mitosis, they exert tensile forces on neighboring cells. We find that mitotic cell–cell junctions withstand these tensile forces through the mechanosensitive recruitment of the actin-binding protein vinculin to cadherin-based adhesions. Surprisingly, vinculin that is recruited to mitotic junctions originates selectively from the neighbors of mitotic cells, resulting in an asymmetric composition of cadherin junctions. Inhibition of junctional vinculin recruitment in neighbors of mitotic cells results in junctional breakage and weakened epithelial barrier. Conversely, the absence of vinculin from the cadherin complex in mitotic cells is necessary to successfully undergo mitotic rounding. Our data thus identify an asymmetric mechanoresponse at cadherin adhesions during mitosis, which is essential to maintain epithelial integrity while at the same time enable the shape changes of mitotic cells.

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The Study of GPIb-VWF Mediated Early-Stage Platelet Activation Triggering On a Single Cell

Blood ◽

10.1182/blood.v120.21.1069.1069 ◽

2012 ◽

Vol 120 (21) ◽

pp. 1069-1069

Author(s):

Lining Ju ◽

Cheng Zhu ◽

Miguel A. Cruz ◽

Yunfeng Chen

Keyword(s):

Platelet Activation ◽

Conflicts Of Interest ◽

Early Stage ◽

Morphological Changes ◽

Morphological Transformation ◽

Second Stage ◽

Biomembrane Force Probe ◽

Interaction Kinetics ◽

High Level ◽

A1 Domain

Abstract Abstract 1069 Binding of GPIbα to VWF tethers platelets to disrupted vascular surface during the haemostatic process. The GPIbα –VWF interaction can also trigger outside-in signaling cascade, resulting in platelet activation, characterized by morphological transformation from discoid to a more spiky shape as well as activation of integrin α IIbβ3. Using the adhesion frequency assay with a biomembrane force probe (BFP), we studied signal initiation by repeated brief contacts of a single platelet with a glass bead coated with VWF-A1 domain and/or fibronectin III 7–10 domain (FNIII7–10) in a precisely controlled fashion (Fig. A). Contacting platelets with beads coated VWF-A1 only resulted in adhesion kinetics mediated by GPIbα –VWF interaction kinetics independent of the activation stage of the platelet. Contacting platelets with beads coated FNIII7–10 only resulted in adhesion kinetics that correlated with the activation stage of the platelet. Discoid-shaped platelets yielded low level adhesions mediated by FN interaction with inactive α IIbβ3 (Fig. B, blue). By comparison, spiky-shaped platelets produced high level adhesions mediated by FN interaction with activated α IIbβ3 (Fig. B, red)that was four times stronger than the interaction with inactive α IIbβ3. Contacting platelets with beads coated both VWF-A1 and FNIII7–10 resulted in two-stage adhesion kinetics. The first stage was mediated by GPIbα –VWF binding, which triggered a second stage consisting of an increase in adhesion after a sub-second delay. The second-stage binding coincided with morphological changes characteristic of platelet activation and matched that mediated by FN interaction with activated α IIbβ3. On the other hand, the concurrent calcium imaging showed as the platelet target was brought to the A1 bead in a repeating manner, the recorded calcium fluorescence intensity climbed up as the repeated touches continue (Fig. C). The peak temporally correlates with the morphological change. Our data indicates that binding of VWF-A1 to platelet GPIbα initiates outside-in signaling, leading to rapid irreversible platelet shape changes and calcium mobilization within a few seconds. Disclosures: No relevant conflicts of interest to declare.

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Twist and chew: three-dimensional tongue kinematics during chewing in macaque primates

Biology Letters ◽

10.1098/rsbl.2021.0431 ◽

2021 ◽

Vol 17 (12) ◽

Author(s):

Kara L. Feilich ◽

J. D. Laurence-Chasen ◽

Courtney Orsbon ◽

Nicholas J. Gidmark ◽

Callum F. Ross

Keyword(s):

Complex Shape ◽

Three Dimensional ◽

Food Type ◽

Power Stroke ◽

Food Bolus ◽

Tongue Movements ◽

Powerful Constraint ◽

Shape Changes ◽

Molar Region

Three-dimensional (3D) tongue movements are central to performance of feeding functions by mammals and other tetrapods, but 3D tongue kinematics during feeding are poorly understood. Tongue kinematics were recorded during grape chewing by macaque primates using biplanar videoradiography. Complex shape changes in the tongue during chewing are dominated by a combination of flexion in the tongue's sagittal planes and roll about its long axis. As hypothesized for humans, in macaques during tongue retraction, the middle (molar region) of the tongue rolls to the chewing (working) side simultaneous with sagittal flexion, while the tongue tip flexes to the other (balancing) side. Twisting and flexion reach their maxima early in the fast close phase of chewing cycles, positioning the food bolus between the approaching teeth prior to the power stroke. Although 3D tongue kinematics undoubtedly vary with food type, the mechanical role of this movement—placing the food bolus on the post-canine teeth for breakdown—is likely to be a powerful constraint on tongue kinematics during this phase of the chewing cycle. The muscular drivers of these movements are likely to include a combination of intrinsic and extrinsic tongue muscles.

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Surface model of the human red blood cell simulating changes in membrane curvature under strain

10.21203/rs.3.rs-467222/v1 ◽

2021 ◽

Author(s):

Philip W. Kuchel ◽

Charles D. Cox ◽

Daniel Daners ◽

Dmitry Shishmarev ◽

Petrik Galvosas

Keyword(s):

Blood Cell ◽

Red Blood Cell ◽

Morphological Changes ◽

Three Dimensional ◽

Membrane Curvature ◽

Glycolytic Flux ◽

Surface Model ◽

Principal Curvatures ◽

Quartic Equation ◽

Shape Changes

Abstract The highly deformable red blood cell (erythrocyte; RBC) responds to mechanically imposed shape changes with enhanced glycolytic flux and cation transport. Such morphological changes are produced experimentally by suspending the cells in a gelatin gel, which is then elongated or compressed in a special apparatus inside an NMR spectrometer. However, direct mathematical predictions of the shapes of the morphed cells have not been reported before. We used recently available functions in Mathematica to triangularize and then compute four types of curvature. The RBCs were described by a previously presented quartic equation in three dimensional (3D) Cartesian space. A key finding was the extent to which the maximum and minimum Principal Curvatures were localized symmetrically in patches at the poles or equators and distributed in rings around the main axis of the strained RBC. The simulations, on the nano-metre to micro-meter scale of curvature, suggest activation of only a subset of the intrinsic mechanosensitive cation channels, Piezo1, during experiments carried out with controlled distortions that persist for many hours. This view is consistent with a recent proposal for non-uniform distribution of Piezo1 molecules around the RBC membrane. On the other hand, if the curvature that gates Piezo1 is at a much finer length scale, then membrane tension will determine local curvature and micron scale curvature as described here will be less likely to influence Piezo1 activity. The geometrical reorganization of the simulated cytoskeleton helps understanding of the concerted metabolic and cation-flux responses of the RBC to mechanically imposed shape changes.

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Micro-Fabric Transformations of Ball Clay in Alkaline Environment

Nature Environment and Pollution Technology ◽

10.46488/nept.2021.v20i04.051 ◽

2021 ◽

Vol 20 (4) ◽

Author(s):

V. Sai Kumar ◽

P. Hari Prasad Reddy ◽

Ch. Rama Vara Prasad

Keyword(s):

Morphological Changes ◽

Analytical Techniques ◽

New Mineral ◽

Case Histories ◽

Morphological Transformation ◽

Sediment Volume ◽

Curing Period ◽

Rate Of Dissolution ◽

Micro Level ◽

Ball Clay

Based on the strong evidence of case histories, this study focused on mineralogical and morphological changes of an artificial kaolinitic soil -Ball clay, when exposed to different concentrations of sodium hydroxide (0.1N, 1N, 4N, and 8N) under different curing periods (7, 28 and 100 days). Sediment volume tests are conducted on Ball clay with all combinations and results are analyzed with the help of analytical techniques. XRD and SEM studies are analyzed to understand the micro-level changes of alkali contaminated Ball clay. Mineralogical and morphological transmutations of Ball clay are investigated for 7, 28, and 100 days curing period. Results revealed new mineral formations like Sodalite under 4N and 8N concentrations of NaOH with 100 days interactions are well observed. The morphological transformation from needle shape to pellet shape is clear evidence of the rate of dissolution and precipitation of minerals under 100 days curing periods.

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Morphological changes of Branched Ge Clusters caused by Diffusion Fields and Surface Roughness of Au Underlayer

MRS Proceedings ◽

10.1557/proc-407-331 ◽

1995 ◽

Vol 407 ◽

Cited By ~ 1

Author(s):

A. Sugawara ◽

T. Kikukawa ◽

Y. Haga ◽

O. Nittono

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Surface Roughness ◽

Diffusion Length ◽

Morphological Changes ◽

Evolution Mechanism ◽

Branching Patterns ◽

Scanning Electron

ABSTRACTThe formation of polycrystalline Ge clusters, during annealing of amorphous Ge/polycrystalline Au bilayers, has been studied by in-situ transmission and scanning electron microscopy. The experimentally observed generation of branching patterns, and the evolution mechanism of branches, are discussed on the basis of finite diffusion length aggregation simulations.

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Effect of Top Dielectric Morphology and Gate Material on the Performance of Nitride-based FLASH Memory Cells

MRS Proceedings ◽

10.1557/proc-1071-f02-08 ◽

2008 ◽

Vol 1071 ◽

Author(s):

Antonio Cacciato ◽

Laurent Breuil ◽

Geert Van den bosch ◽

Olivier Richard ◽

Aude Rothschild ◽

...

Keyword(s):

Fermi Level ◽

Morphological Changes ◽

Electron Injection ◽

Nitride Layer ◽

Device Fabrication ◽

Morphological Transformation ◽

K Value ◽

Fermi Level Pinning ◽

High K ◽

High K Dielectric

AbstractThe nitride-based SONOS cell, for its excellent scalability and process simplicity, is the candidate to push the scaling roadmap for FLASH memories beyond the limit imposed on floating-gate memories by the electrostatic interference between adjacent cells. The traditional SONOS cell consists of a nitride layer (the storage element) encapsulated by two SiO2 layers which isolate the nitride layer from the Si substrate and the poly-Si gate (Poly-Si/SiO2/Si3N4/SiO2/c-Si). However, the thick tunnel oxide necessary to meet the retention requirements imposes a severe limit on the erase performance because of the erase saturation phenomenon. One possibility to guarantee both the erase and the retention performance is the replacement of the top SiO2 layer with materials of higher dielectric constant (high-k dielectric). The presence of a high-k dielectric reduces the electric field across the top dielectric, thus decreasing the unwanted parasitic electron injection from the gate during the erase operation. This will allow the cell to erase deep so to meet a basic requirement for Gigabit multilevel NAND memories. The introduction of high-k materials in the SONOS stack is unfortunately not straightforward. One problem is the Fermi-level pinning at the poly-Si/high-k interface. Another problem is the morphological changes the high-k material undergoes during the device fabrication thermal budget. These changes can modify the k-value and affect the band offset between gate and high-k material. The results may, in both cases, be the decrease of the barrier for electron injection from the gate and, as a consequence, the deterioration of the erase performance. In this paper we study the effect of gate material and of the morphological transformation associated with the high-k post deposition anneal on the erase and the retention behaviour of nitride-based cells. Two different high-k dielectrics are investigated: Al2O3 (which has already been found to be able to significantly improve the erase operation, guaranteeing at the same time excellent endurance and sufficient bake retention) and HfAlO. We show that both for Al2O3 and HfAlO a trade-off exists between erase and retention, higher PDA temperatures being beneficial for erase but detrimental for retention. We also discuss the effect of Fermi level pinning and poly-Si depletion on the erase behaviour and compare the erase performances of several PVD- and AVD-deposited metal gates.

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Effect of the Strength of Attraction Between Nanoparticles on Wormlike Micelle- Nanoparticle System

Condensed Matter ◽

10.3390/condmat3040031 ◽

2018 ◽

Vol 3 (4) ◽

pp. 31

Author(s):

Mubeena Shaikh

Keyword(s):

Self Assembly ◽

Morphological Changes ◽

Attractive Interaction ◽

Morphological Transformation ◽

Wormlike Micelle ◽

Nanoparticle Clusters ◽

The Matrix ◽

Nanoparticle System ◽

Equilibrium Polymers ◽

Percolating Network

The nanoparticle-Equilibrium polymer (or Wormlike micellar) system shows morphological changes from percolating network-like structures to non-percolating clusters with a change in the minimum approaching distance (EVP-excluded volume parameter) between nanoparticles and the matrix of equilibrium polymers. The shape anisotropy of nanoparticle clusters can be controlled by changing the polymer density. In this paper, the synergistic self-assembly of nanoparticles inside equilibrium polymeric matrix (or Wormlike micellar matrix) is investigated with respect to the change in the strength of attractive interaction between nanoparticles. A shift in the point of morphological transformation of the system to lower values of EVP as a result of a decrease in the strength of the attractive nanoparticle interaction is reported. We show that the absence of the attractive interaction between nanoparticles leads to the low packing of nanoparticle structures, but does not change the morphological behavior of the system. We also report the formation of the system spanning sheet-like arrangement of nanoparticles which are arranged in alternate layers of matrix polymers and nanoparticles.

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