Twisted Strands Research Articles

Utilizing Helicoidal and Translational Symmetries Together in 2-D Models of Twisted Litz Wire Strand Bundles

In this paper, a helicoidally symmetric 2-D model of a twisted litz wire strand bundle is studied. Suitable foundations for compatibility tools are presented in order to use such a model as a part of a larger system which does not follow a helicoidal symmetry. A measure for the symmetricity of a field is proposed. This provides the foundations for the coupling of helicoidally symmetric and translationally symmetric models with good understanding of the introduced approximation error.

Analysis and Research on Gap Model of Twisted Strand Steel Wire

The breaking of steel core in the early stage of steel wire rope is a very important factor that restricts the service life of steel wire rope. By analyzing the failure of steel core broken wire, it is found that the key factor affecting the force of twisted strands is the establishment of wire gap model. Based on this, two mathematical models of the elliptic hypothesis and the non-elliptic hypothesis of the steel wire section in twisted strands are established, and two formulas for calculating the steel wire gap are derived. When the steel wire twist Angle is within a certain range, the gap of these two models is very close, but when the twist Angle exceeds a certain value, the difference between the steel wire gap becomes larger and larger. Based on this, the non-elliptic model is used to design different steel core lay lengths, and the experiment verifies that the elastic modulus of the elastic model is close to that of the steel wire rope, which reduces the tensile stress on the steel core when the steel wire rope is used, and improves the phenomenon of steel core breaking.

A New Detection Method Based on Magnetic Leakage Theory and BP Neural Network for Broken Steel Strands in ACSR Conductor

Aluminum conductor steel-reinforced (ACSR) conductor is characterized by inner tensile body of steel core and outer twisted aluminum wire strands, which is obviously different from common steel wire ropes (SWRs) or cables. However, the existing studies are mainly focused on the magnetic flux leakage (MFL) testing of the SWR defects, few or not related to broken steel strands in ACSR conductors. Thus, the leakage magnetic field distributions of SWR and ACSR defects are compared and analyzed by the theoretical and numerical calculations. By considering the nonconductivity characteristics of aluminum wire strands, the steel-air model is established to calculate the effects of fracture width and the number of broken steel strands on the MFL signal for ACSR conductors. Based on the spatial distribution characteristics of ACSR leakage field with low intensity, weak lifting-off effect, and weak circumferential correlation, a single-channel signal processing method with time–frequency domain coupling is proposed. Multiple sets of characteristic values of MFL signal both in time and time–frequency domains are extracted to construct a back propagation (BP) neural network for broken steel strand identification. The results have shown that the improved single-channel time–frequency analysis method has higher accuracy in identifying the ACSR fracture width and the number of broken steel strands compared to the image processing method with multichannel leakage data fusion. With the improved method, the detection error of the fracture width is less than 2 mm, and the accuracy of the number of broken strands can reach 91.67%.

Symmetric Tangling of Honeycomb Networks

Symmetric, elegantly entangled structures are a curious mathematical construction that has found their way into the heart of the chemistry lab and the toolbox of constructive geometry. Of particular interest are those structures—knots, links and weavings—which are composed locally of simple twisted strands and are globally symmetric. This paper considers the symmetric tangling of multiple 2-periodic honeycomb networks. We do this using a constructive methodology borrowing elements of graph theory, low-dimensional topology and geometry. The result is a wide-ranging enumeration of symmetric tangled honeycomb networks, providing a foundation for their exploration in both the chemistry lab and the geometers toolbox.

Golden Quartic Polynomial and Moebius-Ball Electron

A symmetrical quartic polynomial, named golden one, can be connected to coefficients of the icosahedron equation as well as to the gyromagnetic correction of the electron and to number 137. This number is not a mystic one, but is connected with the inverse of Sommerfeld’s fine-structure constant and this way again connected with the electron. From number-theoretical realities, including the reciprocity relation of the golden ratio as effective pre-calculator of nature’s creativeness, a proposed closeness to the icosahedron may point towards the structure of the electron, thought off as a single-strand compacted helically self-confined charged elemantary particle of less spherical but assumed blunted icosahedral shape generated from a high energy double-helix photon. We constructed a chiral Moebius “ball” from a 13 times 180˚ twisted double helix strand, where the turning points of 12 generated slings were arranged towards the vertices of a regular icosahedron, belonging to the non-centrosymmetric rotation group I532. Mathematically put, we convert the helical motion of an energy quantum into a stationary motion on a Moebius stripe structure. The radius of the ball is about the Compton radius. This chiral closed circuit Moebius ball motion profile can be tentatively thought off as the dominant quantum vortex structure of the electron, and the model may be named CEWMB (Charged Electromagnetic Wave Moebius Ball). Also the gyromagnetic factor of the electron (ge = 2.002319) can be traced back to this special structure. However, nature’s energy infinity principle would suggest a superposition with additional less dominant (secondary) structures, governed also by the golden mean. A suggestion about the possible structure of delocalized hole carriers in the superconducting state is given.

Residue-based program of a β-peptoid twisted strand shape via a cyclopentane constraint.

N-Substituted peptides, such as peptoids and β-peptoids, have been reported to have unique structures with diverse functions, like catalysis and manipulation of biomolecular functions. Recently, the preorganization of monomer shape by restricting bond rotations about all backbone dihedral angles has been demonstrated to be useful for de novo design of peptoid structures. Such design strategies are hitherto unexplored for β-peptoids; to date, no preorganized β-peptoid monomers have been reported. Here, we report the first design strategy for β-peptoids, in which all four backbone dihedral angles (ω, ϕ, θ, ψ) are rotationally restricted on a per-residue basis. The introduction of a cyclopentane constraint realized the preorganized monomer structure and led to a β-peptoid with a stable twisted strand shape.

Tight conformation of 2-bridge knots using superhelices

The ropelength is a mathematical quantity that regulates the tightness of flexible strands in the three-dimensional space. The superhelical conformation of long twisted strands is known to be more efficient in terms of ropelength compared with the circular double helical conformation. In this paper, we present a conformation of 2-bridge knots by using ropelength-minimizing superhelical curves and derive an upper bound on the ropelength of 2-bridge knots. Our superhelical model of 2-bridge knots is shown to be more efficient than the standard double helical one if the iterative twisted parts are long enough.

Nanomedicine: A Promising Way to Manage Alzheimer's Disease.

Alzheimer’s disease (AD) is a devastating disease of the aging population characterized by the progressive and slow brain decay due to the formation of extracellular plaques in the hippocampus. AD cells encompass tangles of twisted strands of aggregated microtubule binding proteins surrounded by plaques. Delivering corresponding drugs in the brain to deal with these clinical pathologies, we face a naturally built strong, protective barrier between circulating blood and brain cells called the blood–brain barrier (BBB). Nanomedicines provide state-of-the-art alternative approaches to overcome the challenges in drug transport across the BBB. The current review presents the advances in the roles of nanomedicines in both the diagnosis and treatment of AD. We intend to provide an overview of how nanotechnology has revolutionized the approaches used to manage AD and highlight the current key bottlenecks and future perspective in this field. Furthermore, the emerging nanomedicines for managing brain diseases like AD could promote the booming growth of research and their clinical availability.

Single hair fiber assessment techniques to discriminate between mineral oil and coconut oil effect on hair physical properties.

To utilize a matrix of single-fiber hair testing methodologies to mechanistically understand the impact of common oiling treatments-coconut oil and mineral oil-on hair strands. Further, the effect of hair twisting-experienced in everyday grooming practices-on hair strength was investigated under different scenarios. Study involved multiple surfactant wash cycles of hair swatches with and without overnight hair oil treatments. Instrumental testing was done on strands from hair swatches-Tensile Extension, Torsional Stretching, and Tensile Extension of twisted hair fibers. Differentiation was observed in tensile and torsional testing parameters with 20 wash cycles, while no statistical significance was observed in single wash. However, when we combine the two stresses together by extending the twisted hair strands, a clear differentiation was seen even in single cycle for coconut oil in comparison with mineral oil and surfactant wash. The differentiation in tensile parameters for twisted fibers becomes much more prominent with multiple cycles. Penetration of coconut oil in hair strands makes the fiber core more flexible and thus helps negotiate the torsional stress at the time of extension. Product benefit discrimination in single-strand testing can be amplified by combining multiple stresses in one testing methodology. Observing the consumer habits and incorporating the torsion component in standard tensile testing of hair helps differentiate the two commonly used hair oiling treatments. Coconut oil was found to significantly increase the tensile strength of twisted fibers owing to its penetration inside hair core.

Mechanical properties of 1670 MPa parallel wire strands at elevated temperatures

High-strength prestressing steel cables serve as main load-bearing components for cable-supported structures, and exposure to high temperatures may result in their prestress loss, leading to failure and even collapse of such structures. This paper experimentally investigates the mechanical properties of 7-wire parallel wire strands with a tensile strength of 1670 MPa. The thermal elongation tests and steady-state tensile tests are conducted on 39 strand specimens at different target temperatures. The complete stress-strain curves including rupture strain are obtained by using charge-coupled device camera systems. The temperature-dependent thermal strain, Young’s modulus, proportional limit, effective yield strength, ultimate strength, ultimate strain and rupture strain are recorded and compared to EC2, ACI 216 and other existing test data. The test results show that parallel wire strands experience obvious strain hardening before 300 °C, and their ductility is significantly improved after 400 °C. It is reasonable to define effective yield strength as the stress at a total strain of 2%. It is found that the existing design code and test data on single wires and twisted strands cannot be directly used for parallel strands. The EC2 provides conservative predictions for ultimate strain, proportional limit, yield strength of parallel wire strands, but fails to capture the full range of stress-strain curves of parallel strands due to ignoring strain hardening effect and underestimating rupture strain. The ACI 216 provides unconservative predictions for reduction factors of ultimate strength of parallel strands. Parallel wire strands have higher thermal strain, higher ultimate strain, higher rupture strain, lower reduction factor of proportional limit than single wires and twisted wire strands. Finally, calculation methods are proposed to mathematically determine the thermal strain, stress-strain curve and reduction factors of these properties, and dividing the stress-strain relationship into elastic, plastic, necking and rupture stage.

Study on critical current of a flexible quasi-isotropic HTS conductor with high engineering current density

This paper presents a flexible quasi-isotropic High Temperature Superconducting (HTS) conductor with high engineering current density. The conductor consists of three components: the inner core is a twisted quasi-isotropic strand (Q-IS) with a circular cross section achieved by symmetrically stacking four sub-stacks of HTS wires and four arc aluminum fillers, the middle component consists of copper layers constructed by copper wires spirally winding around the inner core, and the outer component consists of HTS layers constructed by HTS wires spirally winding around the middle section, which is similar to the manufacturing method used for HTS cable or CORC cable. After the three-dimensional finite-element simulation model of the proposed HTS conductor is established, the dependence of the magnetic field and critical current distributions on the twisting pitch of the inner Q-IS and the winding pitch of the outer HTS cable layers are analyzed. Consequently, the model HTS conductor is designed and fabricated, and the critical current of this HTS conductor is measured in liquid nitrogen. The results show that the simulated results are in good agreement with the experimental ones. It is predicted that this type of HTS conductor has potential applications in fusion magnet and power transmission.

Elastic fibers: The missing key to improve engineering concepts for reconstruction of the Nucleus Pulposus in the intervertebral disc

The increasing prevalence of low back pain has imposed a heavy economic burden on global healthcare systems. Intense research activities have been performed for the regeneration of the Nucleus Pulposus (NP) of the IVD; however, tissue-engineered scaffolds have failed to capture the multi-scale structural hierarchy of the native tissue. The current study revealed for the first time, that elastic fibers form a network across the NP consisting of straight and thick parallel fibers that were interconnected by wavy fine fibers and strands. Both straight fibers and twisted strands were regularly merged or branched to form a fine elastic network across the NP. As a key structural feature, ultrathin (53 ± 7 nm), thin (215 ± 20 nm), and thick (890 ± 12 nm) elastic fibers were observed in the NP. While our quantitative analysis for measurement of the thickness of elastic fibers revealed no significant differences (p < 0.633), the preferential orientation of fibers was found to be significantly different (p < 0.001) across the NP. The distribution of orientation for the elastic fibers in the NP represented one major organized angle of orientation except for the central NP. We found that the distribution of elastic fibers in the central NP was different from those located in the peripheral regions representing two symmetrically organized major peaks (±45⁰). No significant differences in the maximum fiber count at the major angles of orientation (±45⁰) were observed for both peripheral (p = 0.427) and central NP (p = 0.788). Based on these new findings a structural model for the elastic fibers in the NP was proposed. The geometrical presentation, along with the distribution of elastic fibers orientation, resulting from the present study identifies the ultrastructural organization of elastic fibers in the NP important towards understanding their mechanical role which is still under investigation. Given the results of this new geometrical analysis, more-accurate multiscale finite element models can now be developed, which will provide new insights into the mechanobiology of the IVD. In addition, the results of this study can potentially be used for the fabrication of bio-inspired tissue-engineered scaffolds and IVD models to truly capture the multi-scale structural hierarchy of IVDs. Statement of SignificanceVisualization of elastic fibers in the nucleus of the intervertebral disk under high magnification was not reported before. The present research utilized extracellular matrix partial digestion to address significant gaps in understanding of nucleus microstructure that can potentially be used for the fabrication of bio-inspired tissue-engineered scaffolds and disk models to truly capture the multi-scale structural hierarchy of discs.

Hydraulic characterization of conductor prototypes for fusion magnets

Forced flow HTS conductors designed for the Winding Demonstrator (WD) or EU DEMO Toroidal Field (TF) and Central Solenoid coils consist of several CroCo or twisted stack monolithic strands, embedded in a stainless steel jacket. Such type of conductors have never been tested for pressure drop. Cable-in-Conduit conductors for the DEMO TF coils designed by ENEA have two low-impedance cooling channels, separated from the cable bundle by flat spirals, with the inner/outer diameter of about 5/7 mm. Experimental pressure drop data for such small spiral ducts are also unavailable yet. To fill this gap, four dedicated short samples, namely dummy conductors with the layout similar to the DEMO HTS or WD conductors and a small spiral-walled pipe have been prepared and tested for pressure drop using demineralised water at 2–3 different temperatures. The tests using water have been performed covering the same range of Reynolds number experienced by the supercritical He at operating conditions typical for DEMO coils. The experimental data have been used to develop experimental friction factor correlations for the considered ducts, which could be utilized in future thermal-hydraulic studies of the DEMO coils or WD.

Nanoparticle formulations in the diagnosis and therapy of Alzheimer's disease.

Alzheimer's disease (AD) is one of the most common age-related diseases that occurs because of the deposition of amyloid fibrils in a form of extracellular plaques containing β-amyloid peptide (Aβ) and tangles are found as intracellular deposit in the brain made up of twisted strands of aggregated microtubule binding protein. Scores of small molecule inhibitors have been designed for the treatment of AD. However some of these drugs cannot pass through the brain-blood-barrier (BBB). To overcome this problem, various nanoparticles (NPs) or nanomedicines (NMs) have been synthesized. These nanoparticles exploit the existing physiological mechanisms of passing through the BBB, including receptor- and adsorptive-mediated transcytosis that facilitate the transcellular transport of nanoparticle from the blood to the brain. During the last decades, varieties of nanoparticles that differ in the composition have been developed, and they have the potential application in the diagnostics and therapy of AD. The most common NP formulations that have major impact in the diagnosis and therapy of AD include polymeric NPs (PPs), gold NPs, gadolinium NPs, selenium NPs, protein-based NPs, polysaccharide-based NPs, etc. The goal of this review is to provide discussion of the application of different types of NP formulations in the diagnosis and therapy of AD.

On Mathematical Braids

A braid is any sequence of crossings of the -strand braid with a positive number n, provided none of the strands are self-crossing. The idea is that braids can be organized into groups, in which the group operation is *, which means: “do the first braid on a set of strands, and then follow it with a second on the twisted strand”. This study dealt with the formulation of additional basic properties of mathematical braids and the connection of mathematical braids to exponential theorems. Moreover, the researchers developed a program that could generate the total number of crossings and the total number of generators in an n-strand braid with a positive number n.

Multi-scale 3D modelling of a DEMO prototype cable from strand to full-size conductor based on X-ray tomography and image analysis

The design of a superconducting magnet system of a fusion reactor candidate is usually based on the Cable in Conduit Conductor (CICC) concept. CICC consist of complex structures with several hundreds of highly packed, multistage twisted superconductor and copper strands, cooling structures – all wrapped in thin steel foils and jacketed in relatively thick stainless-steel pipes. As recently demonstrated, such complex morphology can be captured by fully 3D X-ray tomography. One of the three alternative winding pack (WP) options for the toroidal field coils of the European DEMO superconducting magnet system as proposed by the Italian ENEA, features a layer-wound WP design adopting a wind-and-react conductor with high aspect ratio rectangular cross section. A multi-physics modelling requiring high accuracy from the strand to the full-size conductor scale was tested on two X-ray tomography systems. For the microstructural integrity analysis of the internal tin one mm diameter Nb3Sn strand, manufactured by Western Superconducting Technologies, a microtomograph with ˜1 μm feature recognition was used. For the full-size conductor (66 x 25 mm2 internal dimensions) a high energy (> 300 kVp) microtomograph with voxel resolution of ˜20 μm was employed. Voids and/or geometrical imperfections were detected, accurately pin-pointed and locally investigated at high resolution before and after heat treatment. Dimensional measurements on the 3D internal structure of the strand showed the small dimensional changes of the strand after the heat treatment. A significant result was the determination of the twist-pitch factor in a purely non-invasive way. The 3D reconstructions of the CICC cables were used to verify the cabling and compaction processes as well as the structural integrity of the strands, wrapping foils and spiral cooling structures. Also, 3D reconstruction of strand trajectories provided a strong input for a multiphysical modelling/interpretation of mechanical–electrical properties of CICC in cryogenic–electromagnetic environments.

Skin stretching device combined with collagen sponge for wound repair

Objective To evaluate the feasibility and clinical efficacy of our self-designed simple skin stretching device combined with collagen sponge for management of severe soft tissue wounds. Methods From September 2015 to October 2017, a consecutive series of 43 patients whose soft tissue wounds could not be closed primarily were enrolled for a therapy using a simple skin stretching device made of round osseous pins and wire combined with collagen sponge. They were 27 males and 16 females, with a mean age of 31.5 years (from 5 to 56 years). There were 18 fresh wounds and 25 old ones. Their skin defects ranged from 5.5 cm × 3.0 cm to 18.0 cm × 7.5 cm. After debridement and vacuum sealing drainage, 2 round osseous pins with a diameter of 2.0 mm or 2.5 mm were driven through the dermis about 1 to 2 cm from both edges of the wound, in parallel with the longitudinal axis of the wound. After the parts of 2 pins exposed outside the skin were bent, they were fixed respectively with a fine wire with 2 twisted strands. The wounds were continuously stitched with eversion suture. The wires and sutures were gradually tightened to contract the wounds until the skin color changed and capillary filling reaction started. Then medical collagen sponge was used to cover the wounds. Next, the wires and sutures were tightened continuously until the wound edges were pulled together. Details of this therapy and its complications were recorded. Follow-up visits were paid until wound healing. Results Of the 43 cases, the wounds were directly closed immediately after primary stretching procedure in 8, closed after skin stretching for 4 to 12 days (average, 7.5 days) in 30, and significantly reduced in 5 which were cured following skin graft. Eventually, 40 cases were followed up for an average of 6.8 months (from 3 to 18 months) and 3 were lost. Aesthetic reoperation was performed in 3 patients who were inflicted with postoperative scar formation after skin graft. Linear healing of the wound edges was achieved in 37 patients without complications like skin necrosis, pathological hyperplasia scar, skin sensation deletion or wound infection, leading to fine appearance and functional recovery. Conclusion Our self-designed simple skin stretching device combined with collagen sponge provides a cost-effective and practical technique for clinical treatment of soft tissue defects, with an advantage of reducing or even avoiding secondary repair with skin graft or skin flap. Key words: Soft tissue injuries; Reconstructive surgical procedures; Wound healing; Collagen sponge; Viscoelastic properties of skin

Mechanical properties of high tensile steel cables at elevated temperatures

This study is motivated by increasingly prevalent use of cable-tensioned spatial steel structures and suspension bridges. Fire is one of the extreme conditions that need to be taken into consideration in the design of such structures. In this paper, steady-state tests have been conducted on steel cables with tensile strength of 1860 MPa, which consist of a group of 7-wire twisted strands, to study their full range of stress strain relationships at elevated temperature. Thermal elongation test of steel cables has also been conducted. A charge-coupled device camera (CCDC) system is used to capture the full range of stress-strain relationship of high tensile strength steel cables till rapture at elevated temperature. The reduction factors of proportional limit, elastic modules, effective yield strength and rupture strength at different temperature were obtained from the steady state tests and compared with that proposed by EN 1992-1-2. The experimental work discovered that EN 1992-1-2 overestimated effective strain up to 2% and ignored the stress-hardening phase for high tensile strength cables within the full temperature range. The effective yield strength with 1.25% strain and a full range of stress-stain model considering stress-hardening phase are proposed. Finally, several sets of reduction factors and thermal elongation coefficient as a function of temperature have been proposed by fitting the test results. The reduction factors of pre-stressing strands proposed by EN 1992-1-2 for pre-stressing concrete is found not suitable for steel cables which are widely used for pre-tensioned steel structures. The reduction factors proposed in the present paper are found to be reasonable for steel cables. The experimental work also shows that the mechanical properties of steel cables at elevated temperature depends on whether the cable is made from straight wires or twisted wires.

Microstructure of β-Sitosterol:γ-Oryzanol Edible Organogels.

Rheology and atomic force microscopy (AFM) were employed to examine the microstructure of β-sitosterol:γ-oryzanol organogels in sunflower oil. Using time-resolved rheology, we followed gel formation, paying specific attention to the fibril aggregation process, which had not been studied in detail previously for this system. Using AFM, we observed gel structures directly and obtained detailed information on the gel structure, far exceeding previous studies. Our analysis suggests that though gels are formed by the self-assembly and aggregation of one-dimensional fibrils, the manner in which these fibrils aggregate into ribbons results in complex structures of higher dimensionality. We emphasize that it is a surprise to find ribbons and not twisted strands. Comparing AFM images of 10% w/w and 20% w/w gelator systems, we observed differences in the degree of branching which are consistent with the rheology. We also observed the individual self-assembled fibrils which make up these gels with much greater clarity than in previous microscopy studies, and the fibril diameters of ∼9.8 nm we measured agree excellently with those obtained from existing small-angle neutron scattering data. These results provide new insight into the structure and formation kinetics of this important organogel system.

Design and fabrication of indigenous 30 kA Nb3Sn CICC for fusion relevant superconducting magnet

“Magnet Technology Development Group” is engaged in focused research and development of indigenous fusion relevant superconducting magnet at Institute for Plasma Research in association with various R&D organizations. The fusion relevant superconducting magnet is under development using a cable in conduit conductor (CICC) with operating current of 30 kA at 12 T and 4.22 K. The 30 kA CICC has been designed in square cross-section (30 mm × 30 mm) consisting twisted Nb3Sn strands and copper strands as superconducting cable, SS316LN tubes as jacket material and SS304L foil as wrapping around the cabled strands. It has been designed on the basis of required critical design parameters, operation requirements and mechanical consideration during its fabrication. Cabling technology required for twisting of Nb3Sn and Copper strand in required configuration of cable is discussed in this paper. The effect of heat treatment on SS316LN jacket material as well as on Nb3Sn strands is mentioned in paper. 100 m long Nb3Sn based CICC is manufactured by pulled through technology on dedicated jacketing line. The manufacturing parameters and quality procedures for development of CICCs is successfully established and have been demonstrated with fabrication of 100 m Nb3Sn based CICC without any technical difficulties.