Unless stated otherwise, samples were imaged at room temperature using a Philips Tecnai T12 electron microscope equipped with an LaB6 filament and operated at an acceleration voltage of 120 kV. Images were taken at a magnification of 52,000x and a defocus value of 1.5 mm on Kodak SO-163 film using low-dose procedures. Films were developed for 12 minutes with fullstrength Kodak D-19 developer at 20°C. All micrographs were visually inspected with a laser diffractometer, and only drift-free images were selected for digitization with a Zeiss SCAI scanner using a step size of 7 mm. Micrographs were binned over 3 ¥ 3 pixels to yield a pixel size of 4.04 Å on the specimen level.
Cytoskeletal Filaments
These filamentous structures include actin filaments, intermediate filaments, and microtubules, which play crucial roles in cellular processes like cell division, motility, and signaling.
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Unless stated otherwise, samples were imaged at room temperature using a Philips Tecnai T12 electron microscope equipped with an LaB6 filament and operated at an acceleration voltage of 120 kV. Images were taken at a magnification of 52,000x and a defocus value of 1.5 mm on Kodak SO-163 film using low-dose procedures. Films were developed for 12 minutes with fullstrength Kodak D-19 developer at 20°C. All micrographs were visually inspected with a laser diffractometer, and only drift-free images were selected for digitization with a Zeiss SCAI scanner using a step size of 7 mm. Micrographs were binned over 3 ¥ 3 pixels to yield a pixel size of 4.04 Å on the specimen level.
Masks for 2D images (A) and 3D maps (B). Areas of a filament inside the mask are shown in grey, areas outside the mask in white. In panel A, the helical axis runs at a 45° angle with the horizontal direction, which represents an arbitrary in-plane rotation angle. The helical axis (i.e. the z-axis) runs parallel to the vertical direction in B. Panels C-F illustrate the need for the circular (or spherical) component of these masks. Rotation of an unmasked segment (C) leads to artefacts (top and bottom in D), due to wrapping effects caused by rotations in the Fourier domain. The application of a circular mask to the original image (E) allows rotation without artefacts (F).
One could argue that because helical segments extend all the way across the image, one would not need the circular or spherical components of these masks. However, as all reference projections are taken as 2D slices from the 3D Fourier transform of the reference map, real-space artefacts may again arise from non-empty corners of the reference upon rotation. To make comparisons between the reference projections and the experimental images consistent, the corners are removed from both the 3D map and the 2D images (
Upon extraction of the segments from the micrographs, apart from the corresponding X-Y coordinates and the figure-of-merit, the particle extraction program also outputs for each segment its in-plane rotation along the helical track, a distinct number for the helix it belongs to, and its position within that helix. The latter information is then used to construct the relevant priors on the orientations of each segment as described above. This process does not require any additional user input when RELION is used for all steps from particle picking to refinement. However, if users provide extracted segments from outside the RELION workflow, then the additional metadata should be provided through an imported STAR file in RELION format. In that case, it may be more convenient to re-pick inside RELION. Alternatively, RELION can read coordinate files in EMAN(2) BOX-format (Tang et al., 2007 (link)), or as plain ASCII files with X and Y coordinates in the first two columns. Therefore, one can also conveniently provide the start and end coordinates of helices in such formats, and re-extract the individual segments inside RELION.
Fourier-space refinement of the complete atomic model against the PHF and SF maps was performed in REFMAC55 (link). A stack of three consecutive monomers from each of the protofilaments was refined in order to preserve nearest-neighbour interactions for the middle chain. Local symmetry restraints were imposed in REFMAC to keep all β-strand rungs identical. Since most of the structure adopts a β-strand conformation, hydrogen-bond restraints were imposed to preserve a parallel, in-register hydrogen-bonding pattern in earlier stages of the model building process. In addition, ϕ/ψ angle restraints were imposed for the polyglycine II region, 333GGG335, and the three-residue β-arc, 347KDR349. The dihedral angles for polyglycine II were taken from Crick’s proposed fold27 (link) (ϕ = −80, ψ =150) and those for the three-residue β-arc from the crystal structure of PDB-entry 1QRE56 (link). Side-chain clashes were detected using MOLPROBITY57 (link) and corrected by iterative cycles of real-space refinement in COOT and Fourier-space refinement in REFMAC. Refinements of atomic models were performed for the FL and PT PHFs and for the FL SF. The refined model from the FL SF was rigid-body fitted into the PT SF map. For each refined structure, separate model refinements were performed against a single half-map, and the resulting model was compared to the other half-map to confirm the absence of overfitting. The final models were stable in refinements without additional restraints. Statistics for the final models are shown in
Most recents protocols related to «Cytoskeletal Filaments»
Example 1
A double cloth, plain weave webbing was produced on a needle loom. Each side of the webbing was constructed of 48 ends of 1600 d, 1000 filament ultra-high molecular weight polyethylene yarns and 24 ends of 1000 d, 192 filament polyester yarns along the edges of the webbing, and 12±2 ppi of 1600 d, 1000 filament ultra-high molecular weight polyethylene yarns. The stuffer yarns were 1500 d, 3×4 Kevlar® cord, and 14 cords (168 yarns) were positioned between the front and back sides of the webbing. Binder yarns of 1600 d, 1000 filament ultra-high molecular weight polyethylene yarn binder were woven between the front and back to secure the sides together. A polyester catch cord (1000 d/192/1.5 z) was used to bind the edges of the webbing.
The webbing had a width of approximately 1.0 inches, a thickness of approximately 0.14 inches and a weight of approximately 58 g/linear yard. The tensile strength of the webbing was approximately 8,000 lbs.
Example 6
Stearic acid was mixed with silver powder (5 g SA:40 g silver) or graphite powder (20 g SA:25 g graphite), these mixtures were deposited as a simple circuits, as rectangular electrodes (20 mm×30 mm×2 mm) or as straight lines (20 mm long, 2 mm wide) (
The printed silver powder had a particle size in the range 0.5 micrometer to 2 micrometer.
Some of the silver samples were sintered 1 hour at 400° C. and 2 hours at 700° C. The 3D printed circuit was tested using two LEDs that were placed in series and lit by electricity passed through the circuit. Conductivity was measured on the straight lines using a multimeter with standard copper wire and commercial conductive 3D printable filament as controls. ECG signals were collected through 3D printed electrodes or standard electrodes and were recorded using a Powerlab 26T unit and labchart software provided by ADInstruments (
In sum, electrically conductive materials may be 3D printed and conductivity may be achieved in non-sintered implants. Two uses for these materials may be for circuits or sensors.
Example 22
A method for preparing a gas diffusion layer for proton exchange membrane fuel cell, includes steps as follows:
-
- (1) preparing the carbon fiber suspension;
- mixing the carbon fiber dispersion with the fibrous binder dispersion, then adding the ceramic fiber of 1 mm length (zirconia fiber), and then shearing and dispersing at a high-speed rate of 1500 r/min to obtain the carbon fiber suspension;
- wherein the carbon fiber dispersion consists of the carbon fiber, the dispersant and water;
- wherein the fibrous binder dispersion consists of the fibrous binder, the dispersant and water;
- wherein the viscosity of dispersion composed of the dispersant and water is 2000 Pa·s in the carbon fiber suspension;
- wherein the dispersant is Tween 60; wherein the amount of the dispersant in the carbon fiber suspension is 1.5 wt % of the amount of water;
- wherein the fibrous binder is the composite filament numbered F-4 in Table 1;
- wherein the length of the carbon fiber is 10-20 mm, the aspect ratio of the carbon fiber is 100-3000, and the mass of carbon fibers with the aspect ratio in the interval [100, 500) accounts for 10 wt % of the total mass of carbon fibers, the mass of carbon fibers with the aspect ratio in the interval [500, 1000) accounts for 60 wt % of the total mass of carbon fibers, the mass of carbon fibers with the aspect ratio in the interval [1000, 2000) accounts for 25 wt % of the total mass of carbon fibers, and the mass of carbon fibers with the aspect ratio in the interval [2000, 3000] accounts for 5 wt % of the total mass of carbon fibers; wherein the amount of the carbon fiber in the carbon fiber suspension is 5 wt % of the amount of water;
- wherein the amount of the ceramic fiber is 5 wt % of the amount of the carbon fiber;
- (2) papermaking and drying the carbon fiber suspension to obtain the carbon fiber base paper;
- wherein the drying temperature is 140° C. and the drying time is 5 min;
- in the prepared carbon fiber base paper, wherein the content of the fibrous binder is 30 wt %;
- (3) cross-linking and curing of the carbon fiber base paper (hot-pressing cross-linking);
- wherein the temperature of hot-pressing cross-linking is 300° C., the time of hot-pressing cross-linking is 5 min, and the pressure applied to the carbon fiber base paper is 5 MPa;
- (4) carbonizing and graphitizing the cross-linked carbon fiber base paper under the protection of argon to obtain a gas diffusion layer for proton exchange membrane fuel cell;
- wherein the carbonization temperature is 1250° C. and the carbonization time is 15 min; wherein the graphitization temperature is 2000° C. and the graphitization time is 5 min.
The prepared gas diffusion layer for proton exchange membrane fuel cell has hydrophilic channels composed of the ceramic fiber, and the pore gradient (that is, the pore size increases or decreases along the thickness direction), and the layer with the smallest pore size is the intrinsic microporous layer; wherein the gas diffusion layer for proton exchange membrane fuel cell has a thickness of 100 μm, a porosity of 70%, a contact angle with water of 145°, a tensile strength of 30 Ma, a normal resistivity of 70 mΩ·cm, an in-plane resistivity of 7 mΩ·cm, and a permeability of 2060 (mL·mm)/(cm2·h·mmAq).
Example 2
The stiffness of a polyurethane based filament was increased by overlaying a shell of a similar monomer chemistry over the core material. The elastomeric core was Tecothane TT-1077A having a flexural modulus of 1,100 psi and the shell material was Tecoplast TP-470 having have a flexural modulus of 300,000 psi. The filament was assumed to have a diameter of 0.12 inches and the core was assumed to have a diameter of 0.11 inches.
The area of the shell was calculated to be 0.0018 in.2 and the area of the core was calculated to be 0.0095 in.2. The area moment of inertia for the shell was calculated to be 2.99e−6 and the area moment of inertia for the core was calculated to be 1.76e−8. The area moment of inertia for a cylindrical filament of elastomeric material was calculated to be 1.02e−5.
The calculated stiffness of the shell was 0.897 and the stiffness of the core was calculated to be 0.00002, resulting in the core-shell elastomer filament having a composite stiffness of 0.897. In comparison, the stiffness of a neat elastomeric filament was calculated to be 0.011 lbf per in2.
As such, adding 16 volume percent of the shell material increases the stiffness by a factor of over 80.
Example 12
To determine the index of clean n-hexane consumption to produce 1 kg of xerogel yarn, a bobbin containing 90 filaments of gel yarn was continually fed into the extraction unit. The Experiment was carried out by changing the feed flow rate of clean solvent in the fourth unit, such that it was possible to measure the residual oil content in the xerogel yarn as a function of the flow rate, awaiting for the stabilization time of the method. Data to the xerogel sample containing about 4% oil is set forth in Table XI.
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More about "Cytoskeletal Filaments"
These filamentous structures include actin filaments, intermediate filaments, and microtubules, which play pivotal roles in cellular processes such as cell division, motility, and signaling.
The cytoskeleton is a dynamic and versatile network that undergoes constant remodeling to adapt to the changing needs of the cell.
Actin filaments, for instance, are involved in cell migration, muscle contraction, and the formation of specialized structures like lamellipodia and filopodia.
Intermediate filaments, on the other hand, provide mechanical support and help maintain the integrity of the cell.
Microtubules, the third major component of the cytoskeleton, act as 'highways' for intracellular transport, facilitating the movement of organelles, vesicles, and other cellular cargo.
They also play a crucial role in cell division, forming the mitotic spindle that segregates chromosomes during mitosis.
Researchers studying cytoskeletal filaments often utilize specialized tools and techniques, such as Von Frey filaments, Dynamic Plantar Aesthesiometer, Fusion 360, and the Vitrobot Mark IV, to visualize and analyze these structures.
Calibrated von Frey filaments and Touch-Test Sensory Evaluators are also commonly used to assess mechanical sensitivity and sensory perception.
By exploring the world of cytoskeletal filaments with the help of advanced AI-driven platforms like PubCompare.ai, researchers can optimize their scientific protocols, identify the most effective methods and products, and take their studies to new heights.
With powerful search and comparison tools, researchers can easily locate the best protocols from literature, preprints, and patents, leveraging AI-driven insights to enhance their cytoskeletal filaments research.