Filament Arrangement Research Articles

Mass production and cutting performance of diamond coated cutting tools for machining titanium alloys

Diamond coated cutting tools are applied for machining difficult-to-machine materials of titanium alloys. However, the temperature field uniformity needs to be further improved for the mass production of diamond coated tools using the hot filament chemical vapor deposition (HFCVD) method. In this paper, the tools temperature distribution is simulated by the finite volume method (FVM) during the deposition of diamond coatings. An optimization method of deposition setting with fine filaments in dense arrangement (FFDA) is proposed, and the temperature distributions of the tools under the coarse filament in sparse arrangement (CFSA) and FFDA are simulated to systematically elucidate the effects of fine filament densification. Subsequently, the different hot filament arrangements are adopted to mass production experiment for deposition of micro/nano composite diamond (MCD/NCD) coatings on WC-6%Co cutting tools. In addition, the cutting experiments on titanium alloys are conducted using diamond coated tools, and the cutting performance of tools at different locations is evaluated. The results indicate that the FFDA method can improve the temperature field uniformity of mass-produced diamond coated cutting tools, and the cutting tools have better consistency in surface morphology, thickness, chemical composition, surface roughness and cutting performance.

Study on the mechanical properties of micropore organic polymer membranes

Abstract Micropore organic polymer membranes are indispensable for membrane filtration with well-established selectivity and permeability. Pressure-driven conditions in harsh acidic or alkaline environments can influence the mechanical properties of these materials. Diminished mechanical properties may include a shortened membrane lifespan, reduced filtration effectiveness, and increased filtration cost. Understanding of the intricate mechanisms influencing the mechanical properties of organic polymer membranes remains incomplete. In this study, a comprehensive investigation was carried out to characterize the mechanical properties of different membrane materials with similar and varying pore size parameters. The influence of different methods of membrane preparation on the mechanical properties of these materials was also explored. Results showed that the PTFE membranes demonstrated excellent Young’s modulus and tensile strength, while PVDF membranes excelled in elongation at break. Organic filter membranes prepared by the phase transition method exhibited a more structured fiber filament arrangement, a smoother surface, reduced crack formation and extension, and uniform pore size and distribution when compared to materials prepared using the tensile method. The results of this study expanded our understanding of the factors that can influence the mechanical properties of organic filtration membranes.

The Influence of Microstructural Arrangement on the Failure Characteristics of 3D-Printed Polymers: Exploring Damage Behaviour in Acrylonitrile Butadiene Styrene.

This study investigated how printing conditions influence the fracture behaviour of 3D-printed acrylonitrile butadiene styrene (ABS) under tensile loading. Dog-bone-shaped ABS specimens were produced using the fusion filament fabrication technique, with varying printing angles. Tensile tests were conducted on pre-notched specimens with consistent pre-notch lengths but different orientations. Optical and scanning electron microscopies were employed to analyse crack propagation in the pre-notched specimens. In order to support experimental evidence, finite element computation was implemented to study the damage induced by the microstructural rearrangement of the filaments when subject to tensile loading. The findings revealed the simple linear correlation between the failure properties including elongation at break and maximum stress in relation to the printing angle for different pre-notch lengths. A more progressive damage was found to support the ultimate performance of the studied material. This experiment evidence was used to build a damage model of 3D-printed ABS that accounts for the onset, growth, and damage saturation. This damage modelling is able to capture the failure properties as a function of the printing angle using a sigmoid-like damage function and a modulation of the stiffness within the raster. The numerical results demonstrated that damage pattern develops as a result of the filament arrangement and weak adhesion between adjacent filaments and explains the diffuse damage kinetics observed experimentally. This study concludes with a topological law relating the notch size and orientation to the rupture properties of 3D-printed ABS. This study supports the idea of tailoring the microstructural arrangement to control and mitigate the mechanical instabilities that lead to the failure of 3D-printed polymers.

Effects of Microstructural Arrangement on the Mechanical Behavior of 3D Printed Polyamide

This study aims to relate the microstructural arrangement, in particular the symmetry materialized by filament sequencing in the fused filament fabrication process, to the mechanical behavior of printed polyamide. Dog-bone structures were printed using various printing temperatures ranging from 250 °C to 280 °C, which were combined with part orientation including vertical, horizontal, and lateral configurations and raster angles (0°, 15°, 30°, and 45°) that represent the in-plane and out-of-plane symmetrical arrangement of the filament. Mechanical testing was conducted on both as-received filaments and printed structures to derive the effects of filament arrangement symmetry and process-generated defects on mechanical loss. In addition, a microstructural analysis using scanning electron microscopy was used to share more light on the filament arrangements and their consequence on the deformation mechanisms with respect to the printing conditions. The results showed that the 3D printed polyamide-based materials exhibited remarkable tensile performance with strain stiffening behavior and large elongation at break due to their particular filament layout. Among the considered printing conditions, the part orientation was found to have the largest influence on the tensile behavior, which modulates the behavior from complete restoration of the filament performance to mechanical loss.

Tuning mechanical properties of 3D printed composites with PLA:TPU programmable filaments

Polylactic acid (PLA) filament is widely used for desktop 3D printing purposes due to its exceptional mechanical properties such as high strength; however, its brittleness restricts its use for producing flexible objects. Thermoplastic polyurethane (TPU) filament which is also widely used for desktop 3D printing, on the other hand, is flexible and commonly used in printing compliant objects with relatively low load-bearing performance. This study investigates the ability to tune the mechanical properties of specimens that are printed using programmable filaments composed of PLA and TPU filaments with different volume ratios of PLA and TPU. Two types of PLA and TPU filament arrangements, i.e., series and parallel, are considered. The PLA:TPU programmable filaments are used to print dogbone specimens for tensile testing. In printing the dogbone specimens, the raster angle is varied, i.e., 0, 45, and 90° with respect to the transverse direction of the specimen. To examine their mechanical behaviors based on different PLA and TPU filament arrangements, compositions, and raster angles, tensile tests are conducted on both programmable filaments and dogbone specimens. This study demonstrates the ability to tune the mechanical properties of printed objects by designing programmable filaments and varying raster angles during printing.

Examination into protein assembly within the cardiac thin filament: Why the troponin complex crosses over.

The major contributor to overall function of the cardiac thin filament (cTF) originates from the presence of the troponin (Tn) complex. Despite its clear importance to the function of the thin filament complex, it proves a challenging complex to study due to it containing highly flexible and unstructured regions. Recent cryo-electon microscopy studies have highlighted the organization of the Tn complex within the thin filament, revealing that the troponin complex “crosses-over” the thin filament. The alpha helical portion of TnT interacting with Tm dimers on one side of the thin filament, while its C-terminal end, with the remainder of the Tn core, interacts with the opposing Tm dimer on the other side. With the additional observation that the Tn core interacts primarily with pseudo-repeat 4 of Tm, this results in a heterogeneous organization of Tn within the thin filament through the flexible linker of TnT. To elucidate why Tn organizes in such a fashion, we will utilize our atomic model for the cardiac thin filament with molecular dynamics simulations to observe the overall structure and energetics when the linker crosses over the thin filament and a scenario when it does not; therefore, Tn interacts with the Tm dimers on the same side. Additionally, we will examine Tn-Tm interactions when the Tn core interacts with the other pseudo-repeats of Tm. In these hypothetical thin filament arrangements, we hope to categorize the residue-residue constants and energetics to explain the preferential thin filament assembly observed experimentally.

Breaking Material Symmetry to Control Mechanical Performance in 3D Printed Objects

Additive manufacturing is a modern manufacturing technology allowing the material structuring at a fine scale. This structuring affects the performance of printed parts. In this study, the quantification of the material arrangement in 3D printed ceramic on the mechanical performance is tackled. The experimental layout considers two main printing parameters, namely, part orientation and printing angle, where 12 different printing configurations are studied. These configurations differ in terms of filament arrangement in the building direction, and within the plane of construction. Material characterisation is undertaken through tensile testing, which are performed for vertical, lateral and longitudinal orientations, and combined with a printing angle of 0°, 15°, 30°, and 45°. In addition, Scanning Electron Microscopy is considered to study how the material symmetry affects the fractured patterns. This analysis is completed with optical imaging and is used to monitor the deformation sequences up to the rupture point. The experimental results show a wide variety of deformation mechanisms that are triggered by the studied printing configurations. This study concludes on the interpretation of the observed trends in terms of mechanical load transfer, which is related to the lack of material connectivity, and the relative orientation of the filaments with respect to the loading directions. This study also concludes on the possibility to tune the tensile performance of 3D printed ceramic material by adjusting both the part orientation and the printing angle.

Ultrastructural and kinetic evidence support that thick filaments slide through the Z-disc.

How myofilaments operate at short mammalian skeletal muscle lengths is unknown. A common assumption is that thick (myosin-containing) filaments get compressed at the Z-disc. We provide ultrastructural evidence of sarcomeres contracting down to 0.44 µm-approximately a quarter of thick filament resting length-in long-lasting contractions while apparently keeping a regular, parallel thick filament arrangement. Sarcomeres produced force at such extremely short lengths. Furthermore, sarcomeres adopted a bimodal length distribution with both modes below lengths where sarcomeres are expected to generate force in classic force-length measurements. Mammalian fibres did not restore resting length but remained short after deactivation, as previously reported for amphibian fibres, and showed increased forces during passive re-elongation. These findings are incompatible with viscoelastic thick filament compression but agree with predictions of a model incorporating thick filament sliding through the Z-disc. This more coherent picture of mechanical mammalian skeletal fibre functioning opens new perspectives on muscle physiology.

Impedance analysis of electrodes made of continuous carbon filaments in a 20 cm2 redox flow cell

• Continuous filament electrodes permit studies on electrode filament arrangements. • Continuous filament electrodes allow for side electrical contact without compression. • A common charge-transfer rate constant, k 0 of 2.2·10 -4 cm s -1 , was estimated. • Mass-transfer resistance improved with non-uniform filament spatial density. The most commonly used electrodes in redox flow batteries are carbon fiber felts, which are assemblies of randomly oriented short fibers. The avenues to improve cell performance are usually pre-treatment to enhance their catalytic activity, modifications of their porosity, and reducing resistivity by increasing compression. Our investigations focus on carbon electrodes made of continuous carbon filaments, where filaments were arranged in specific geometric patterns in order to investigate the effect of the fiber density and spatial distribution across direction of flow on the cell performance. To identify the source of cell voltage losses, electrochemical evaluations were performed with electrochemical impedance spectroscopy (EIS), and compared with commonly used felt electrodes. The electrochemically reversible ferri/ferrocyanide system at 50% state-of-charge (SOC) was used as redox probe for both anolyte and catholyte to avoid varying electrode activities of anode/cathode due to differences in redox species. The findings generate electrode design considerations to reduce voltage losses in redox flow batteries.

Traveling-wave antenna model for terahertz radiation from laser-plasma interactions

Generation of terahertz (THz) wave from air plasma induced by femtosecond laser pulses with a single central frequency (the so-called "single-color") is one of the fundamental interactions between light and matter, and is also the basis of subsequent pumping schemes using two- or multi-color laser fields. Recently, more states of media beyond gas (e.g., atomic cluster and liquid) via photo-ionization have brought new experimental observations of THz radiation, which can no longer be simply attributed to the mainstream model of the transition-Cherenkov radiation (TCR), thus making the whole picture unclear. Here, we revisited the mechanism of this dynamic process in a new view of the traveling-wave antenna (TWA) model. By successfully reproducing the reported far-field THz radiation profiles from various plasma filament arrangements, the wide applicability of the TWA theory has been revealed. On the other hand in the microscopic view, we investigated the plasma oscillation during filamentation aiming at further bridging the plasma filament and the antenna. Accordingly, THz-plasma resonance has been theoretically and experimentally demonstrated as the elementary THz emitter, paving the way towards fully understanding this important single-color plasma based THz source.

Aftiphilin Regulation of Myosin Light Chain Kinase Activity Promotes Actin Dynamics and Intestinal Epithelial Barrier Function

The expression levels of aftiphilin (AFTPH) are significantly lower in inflamed colonic tissues from patients with ulcerative colitis (UC) and mice with experimental colitis. During colonic inflammation, the selective permeability of the colonic epithelium is compromised largely due to dysregulation of proteins associated with either the tight junction (TJ) complex and actomyosin contraction rings. Here, we hypothesized that inflammation-associated reduction in AFTPH levels might cause an increase in the selective permeability of the colonic epithelium. In this study, we measured the transepithelial electric resistance (TEER), sodium (Na+) ion flux and dextran permeability in polarized colonic epithelial cells after manipulation of AFTPH. Silencing of AFTPH reduced TEER, increased Na+ ion flow and dextran permeability. Examination of mRNA and protein levels of multiple TJ proteins and Na+ ion transporters suggested that AFTPH deficiency did not significantly change expression of most of these transmembrane proteins. While the gross structure of the TJs in AFTPH gene-silenced cells appeared normal, elevated levels of junctional Occludin were observed. Most notably we observed that AFTPH co-localized with myosin light chain kinase (MLCK) and attenuated cellular MLCK activity as observed by phospho- myosin light chain 2 (pMLC2) western blots. Importantly, inhibition of MLCK activity reversed the reduction of TEER in AFTPH-deficient monolayers. Lastly, examination of microvilli by transmission electron microscopy and immunofluorescence imaging of actin filament arrangement demonstrated that AFTPH deficiency also affected filament arrangement in colonic epithelial cells. Taken together, these results suggest that AFTPH regulates intestinal epithelial permeability and actin polymerization in colonic epithelium through interfering with MLCK/MLC interactions.

The first phylogenetic and species delimitation study of the nudibranch genus Gymnodoris reveals high species diversity (Gastropoda: Nudibranchia)

Nudibranchs are charismatic marine gastropods that lack a shell in the adult stage. While most nudibranchs feed on sessile animals such as sponges, bryozoans, and cnidarians, the nudibranch genus Gymnodoris Stimpson, 1855 evolved a more active and predatory lifestyle, including sea slug predation, cannibalism, and oddly enough, fish-fin parasitism. At the beginning of our work, no phylogenetic hypothesis existed for the genus, nor a clear picture of how Gymnodoris is related to other nudibranchs. Here we set out to reconstruct Gymnodoris phylogeny, investigate species diversity, and clarify the status of the genus name Analogium, which had been proposed for members of the genus with a linear gill filament arrangement. We present the first phylogenetic hypothesis for Gymnodoris, reconstructed by maximum likelihood and Bayesian inference using two mitochondrial and two nuclear loci, with gill filament arrangement plotted on the phylogeny. The backbone of the phylogeny remains unresolved with theseloci, however, we found that Gymnodoris comprises three main well-supported clades, which we refer to as the “subornata”, “citrina” and “varied” clade, the latter two clades being comprised of several well-supported subclades. The sister group to Gymnodoris is a clade including the genera Vayssierea and Lecithophorus. Based on ABGD and PTP species delimitation methods, we conservatively estimate 65–70 species comprise our dataset. We further estimate that approximately 81% of the species we sampled are undescribed, and note that a linear gill filament arrangement has evolved multiple times within the genus. Gymnodoris is only monophyletic when the species with a linear gill arrangement are included. Therefore, at this time, we agree with the synonymy of Analogium striata with Gymnodoris striata by Rudman and Darvell (1990) and that the genus name Analogium is warranted as a junior synonym of Gymnodoris. Given the extensive undescribed diversity, and lack of resolution at some of the nodes in the phylogeny, patterns of diversification in diet are impossible to discern at this time and will require a large effort to both describe Gymnodoris species diversity and the diets of these candidate species.

Electrodes Made of Continuous Carbon Filament Rovings: Effect of the Filament Arrangement on Cell Voltage Losses in a 20-Cm2 Redox Flow Cell

Electrodes Made of Continuous Carbon Filament Rovings: Effect of the Filament Arrangement on Cell Voltage Losses in a 20-Cm2 Redox Flow Cell

Electrodes Made of Continuous Carbon Filament Rovings: Effect of the Filament Arrangement on Cell Voltage Losses in a 20-Cm2 Redox Flow Cell

Electrodes Made of Continuous Carbon Filament Rovings: Effect of the Filament Arrangement on Cell Voltage Losses in a 20-Cm2 Redox Flow Cell

Differential Collective Cell Migratory Behaviors Modulated by Phospholipid Nanocarriers.

Phospholipid nanocarriers have been widely explored for theranostic and nanomedicine applications. These amphiphilic nanocarriers possess outstanding cargo encapsulation efficiency, high water dispersibility, and excellent biocompatibility, which render them promising for drug delivery and bioimaging applications. While the biological applications of phospholipid nanocarriers have been well documented, the fundamental aspects of the phospholipid-cell interactions beyond cytotoxicity have been less investigated. In particular, the effect of phospholipid nanocarriers on collective cell behaviors has not been elucidated. Herein, we evaluate the interactions of phospholipid nanocarriers possessing different functional groups and sizes with normal and cancerous immortalized breast epithelial cell sheets with varying metastatic potential. Specifically, we examine the impact of nanocarrier treatments on the collective migratory dynamics of these cell sheets. We observe that phospholipid nanocarriers induce differential collective cell migratory behaviors, where the migration speed of normal and cancerous breast epithelial cell sheets is retarded and accelerated, respectively. To a certain extent, the nanocarriers are able to alter the migration trajectory of the cancerous breast epithelial cells. Furthermore, phospholipid nanocarriers could modulate the stiffness of the nuclei, cytoplasm, and cell-cell junctions of the breast epithelial cell sheets, remodel their actin filament arrangement, and regulate the expressions of the actin-related proteins. We anticipate that this work will further shed light on nanomaterial-cell interactions and provide guidelines for rational and safer designs and applications of phospholipid nanocarriers for cancer theranostics and nanomedicine.

Hot filament chemical vapor deposition temperature field optimization for diamond films deposited on silicon nitride substrates

The influence of some key parameters of hot filament chemical vapor deposition (HFCVD) on the temperature distribution during the deposition of diamond coatings on silicon nitride (Si3N4) substrates was assessed with the help of the finite element method. Solid heat transfer, fluid heat transfer and surface radiation heat transfer mechanisms were used to calculate the substrate temperature in the steady state during the deposition process. The accuracy of the model was verified by comparing the simulation model with experimental measurements. The comparison shows that the deviation between the model and the actual substrate temperature measurements is within 3%. Furthermore, a Taguchi orthogonal experiment was designed (3 factors, 3 levels, L9). By changing the number of hot filaments, the distance between the filaments and the substrate, and the separation between two adjacent hot filaments, the influence trend of these parameters on the substrate temperature was assessed, leading to an optimal hot filament arrangement. A deposition experiment was carried out using the optimized parameters, and the results showed that the substrate surface temperature obtained by numerical simulation is highly consistent with the temperature measured by the infrared thermometer. The optimized deposition parameters contributed to a more suitable temperature range and more uniform temperature distribution on the Si3N4 ceramic substrate. The deposited diamond film exhibited uniform crystal quality and grain morphology, thus verifying the validity of the simulation results.

Transmission characteristics of electromagnetic waves in a semicircular plasma filament layer generated by a femtosecond laser

AbstractThe transmission characteristics of electromagnetic (EM) waves in a semicircular plasma filament layer generated by a femtosecond laser were studied in a wide frequency band including radar waves. We have focussed on the influence of plasma parameters and filament arrangement based on the diffraction and superposition theory of EM waves on the transmittance. A numerical simulation model using the current density convolution finite‐difference time‐domain method was constructed in a semicircular multilayer filament structure, and the transmission characteristics of spherical EM waves were examined. The simulation results showed that in this semicircular structure, the transmittance was periodically changed at a frequency interval corresponding to the thickness of the filament channel. This phenomenon was more pronounced as the number of the filament layers increased. In the lower band (<30 GHz), there was little change in the transmittance according to layer‐to‐layer distance, but in the higher band (>30 GHz), it changed irregularly. On the contrary, for the electron number density, it changed regularly in the lower frequency and hardly changed in the higher frequency. When the number of layers was 3 or more, the transmittance became 0 at the centre of the channel, and a discontinuous interference pattern appeared more clearly as the frequency increased.

Fused filament fabrication 3D printed polylactic acid electroosmotic pumps.

Additive manufacturing (3D printing) offers a flexible approach for the production of bespoke microfluidic structures such as the electroosmotic pump. Here a readily accessible fused filament fabrication (FFF) 3D printing technique has been employed for the first time to produce microcapillary structures using low cost thermoplastics in a scalable electroosmotic pump application. Capillary structures were formed using a negative space 3D printing approach to deposit longitudinal filament arrangements with polylactic acid (PLA) in either "face-centre cubic" or "body-centre cubic" arrangements, where the voids deliberately formed within the deposited structure act as functional micro-capillaries. These 3D printed capillary structures were shown to be capable of functioning as a simple electroosmotic pump (EOP), where the maximum flow rate of a single capillary EOP was up to 1.0 μl min-1 at electric fields of up to 750 V cm-1. Importantly, higher flow rates were readily achieved by printing parallel multiplexed capillary arrays.

X-ray microtomography investigations on the residual pore structure in silicon nitride bars manufactured by direct ink writing using different printing patterns

Printing bulk parts by Direct Ink Writing (DIW) is challenging. Aspects like the printing strategy (pathways followed by the nozzle) or drying parameters can have a significant influence on the quality of the resulting sample, besides the rheological characteristics of the ink. Different drying methods and building substrates were tested to avoid warping and cracks. Furthermore, bars were printed using different printing patterns, in terms of filament alignment and direction. The influence of these printing patterns on residual pore sizes and pore distributions were investigated by X-ray microtomography. In this way, it was possible to determine the size and distribution of pores for both green and sintered parts and to identify the presence of repetitive patterns as a function of the filament arrangement. The porosity was correlated to the density of the parts, and no influence of the printing strategy on the density of the final parts was detected.

Actin filaments mediated root growth inhibition by changing their distribution under UV-B and hydrogen peroxide exposure in Arabidopsis

BackgroundUV-B signaling in plants is mediated by UVR8, which interacts with transcriptional factors to induce root morphogenesis. However, research on the downstream molecules of UVR8 signaling in roots is still scarce. As a wide range of functional cytoskeletons, how actin filaments respond to UV-B-induced root morphogenesis has not been reported. The aim of this study was to investigate the effect of actin filaments on root morphogenesis under UV-B and hydrogen peroxide exposure in Arabidopsis.ResultsA Lifeact-Venus fusion protein was used to stain actin filaments in Arabidopsis. The results showed that UV-B inhibited hypocotyl and root elongation and caused an increase in H2O2 content only in the root but not in the hypocotyl. Additionally, the actin filaments in hypocotyls diffused under UV-B exposure but were gathered in a bundle under the control conditions in either Lifeact-Venus or uvr8 plants. Exogenous H2O2 inhibited root elongation in a dose-dependent manner. The actin filaments changed their distribution from filamentous to punctate in the root tips and mature regions at a lower concentration of H2O2 but aggregated into thick bundles with an abnormal orientation at H2O2 concentrations up to 2 mM. In the root elongation zone, the actin filament arrangement changed from lateral to longitudinal after exposure to H2O2. Actin filaments in the root tip and elongation zone were depolymerized into puncta under UV-B exposure, which showed the same tendency as the low-concentration treatments. The actin filaments were hardly filamentous in the maturation zone. The dynamics of actin filaments in the uvr8 group under UV-B exposure were close to those of the control group.ConclusionsThe results indicate that UV-B inhibited Arabidopsis hypocotyl elongation by reorganizing actin filaments from bundles to a loose arrangement, which was not related to H2O2. UV-B disrupted the dynamics of actin filaments by changing the H2O2 level in Arabidopsis roots. All these results provide an experimental basis for investigating the interaction of UV-B signaling with the cytoskeleton.