Number Of Kinks Research Articles

Understanding the Role of Surface Chemistry in Nanocellulose Kink Formation: A Case Study of TEMPO-Mediated Oxidation.

This study found that the sources of cellulose have a significant effect on the parameters related to the kinks present in nanocellulose. During nanocellulose preparation, 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation induced partial depolymerization on whole cellulose and made the amorphous regions more susceptible to consequent mechanical treatment irrespective of cellulose sources. However, plant cellulose microfibrils were prone to break into shorter nanocellulose with fewer kinks, while bacterial and tunicate cellulose were more likely to bend rather than break, thus leading to the generation of more kinks. The kinks did not show significant effects on the size, crystallinity index, and thermal properties of nanocellulose for each cellulose source, though the kink numbers were positively related to the mechanical performance of nanocellulose. Collectively, this study elucidated the kink formation mechanisms and clarified the effects of kinks on nanocellulose performance, thus providing new insights into understanding the source and behaviors of microdefects present in nanocellulose.

Learning topological defects formation with neural networks in a quantum phase transition

Neural networks possess formidable representational power, rendering them invaluable in solving complex quantum many-body systems. While they excel at analyzing static solutions, nonequilibrium processes, including critical dynamics during a quantum phase transition, pose a greater challenge for neural networks. To address this, we utilize neural networks and machine learning algorithms to investigate time evolutions, universal statistics, and correlations of topological defects in a one-dimensional transverse-field quantum Ising model. Specifically, our analysis involves computing the energy of the system during a quantum phase transition following a linear quench of the transverse magnetic field strength. The excitation energies satisfy a power-law relation to the quench rate, indicating a proportional relationship between the excitation energy and the kink numbers. Moreover, we establish a universal power-law relationship between the first three cumulants of the kink numbers and the quench rate, indicating a binomial distribution of the kinks. Finally, the normalized kink-kink correlations are also investigated and it is found that the numerical values are consistent with the analytic formula.

Kink Sum for Long-Memory Small Matrix Path Integral Dynamics.

The small matrix decomposition of the real-time path integral (SMatPI) allows for numerically exact and efficient propagation of the reduced density matrix (RDM) for system-bath Hamiltonians. Its high efficiency lies in the small size of the SMatPI matrices employed in the iterative algorithm, whose size is equal to that of the full RDM. By avoiding the storage and multiplication of large tensors, the SMatPI algorithm is applicable in multistate systems under a variety of conditions. The main computational effort is the evaluation of path sums within the entangled memory length to construct the SMatPI matrices. A number of methods are available for this task, each with its own favorable parameter regime, but calculations with strong system-bath coupling and long memory at low temperatures remain out of reach. The present paper evaluates the path sums by binning the paths (in forward time only) based on their amplitudes, which depend on the number and type of kinks they contain. The algorithm is very efficient, leading to a dramatic acceleration of path sums and significantly extending the accessible memory length in the most challenging regimes.

Simulation of the hexagonal 3D braiding process for stent preforms

Due to the complex braiding process and long development cycle of the hexagonal three-dimensional braided stent, a MatLab based computer-aided braiding method for a stent is proposed to speed up the development process. First, an oblique coordinate system for the chassis and a polar coordinate system for the chassis unit are constructed, respectively, precisely to coordinate the carrier’s movements on the chassis. Subsequently, an iterative formula delineating the trajectory of the carrier is introduced. The formula effectively translates the entire braiding process into the positional coordinates of the carrier on the chassis and the yarn heights on the mandrel during different stages. Based on the specific characteristics of the braiding process and the stent’s structure, the stent is divided into pressing and twisting sections. The interwoven pattern for both the pressing and twisting sections is determined by establishing the basic tiling form, solving the yarn interwoven sequence, judging the interwoven type and computing the number of kinks. Finally, while considering the stent's dimensional parameters and the interwoven pattern of the yarn, the spatial curve equations for the yarns in both the pressing and the twisting sections are formulated. By concatenating these equations for each section, the three-dimensional trajectory equations and a comprehensive solid model of the stent are successfully derived. Through a rigorous comparative analysis of dimensions and the braiding pattern between the three-dimensional solid model and the physical stent preform, the accuracy and fidelity of the model generated through the implementation of computer-aided braiding technology are verified.

Size and kink effects on thermal conductivity in nickel nanowires

The potential applications of nanowires in thermal management and thermoelectric energy conversion have sparked extensive research on thermal transport in various nanowires. Nickel nanowires, with their unique properties and promising applications, have been extensively studied. However, the influence of size, particularly the impact of kink structures, on the thermal transport behavior in nickel nanowires remains unclear. In this paper, we employed electron-beam lithography and liftoff techniques to fabricate suspended nickel nanowires with varying sizes and kinks to experimentally investigate the size and kink effect on the thermal conductivity. The experimental results revealed that the thermal transport behavior of nickel nanowires is significantly influenced by both size and kink effects. Notably, as the nanowire size decreases, the thermal conductivity also decreases. Furthermore, we discovered that the thermal conductivity can be adjusted by altering the number and angle of kinks. Increasing the number of kinks from 18 to 36 resulted in a significant decrease in thermal conductivity. In contrast, as the kink angle decreased from 157° to 90°, the thermal conductivity also decreased. However, intriguingly, when the kink angle was further decreased from 90° to 43°, the thermal conductivity increases. This non-monotonic change in thermal conductivity with the kink angle provides an interesting insight into the intricate behavior of heat carriers in kinked nickel nanowires. Additionally, we found that varying the alloy elements can profoundly alter the thermal conductivity of nanowires with kinks. These results offer valuable insights into the behaviors of heat carriers, including electrons and phonons, during heat transfer in nickel nanowires.

Kink–antikink interaction forces and bound states in a nonlinear Schrödinger model with quadratic and quartic dispersion

In the present work we explore the competition of quadratic and quartic dispersion in producing kink-like solitary waves in a model of the nonlinear Schrödinger type bearing cubic nonlinearity. We present the first 6 families of multikink solutions and explore their bifurcations as the strength of the quadratic dispersion is varied. We reveal a rich bifurcation structure for the system, connecting two-kink states with states involving 4-, as well as 6-kinks. The stability of all of these states is explored. For each family, we discuss a “lower branch” adhering to the energy landscape of the 2-kink states. We also, however, study in detail the “upper branches” bearing higher numbers of kinks. In addition to computing the stationary states and analyzing their stability within the partial differential equation model, we develop an effective particle ordinary differential equation theory that is shown to be surprisingly efficient in capturing the kink equilibria and normal (as well as unstable) modes. Finally, the results of the bifurcation analysis are corroborated by means of direct numerical simulations involving the excitation of the states in a targeted way in order to explore their instability-induced dynamics.

Mobile Kink Solitons in a Van der Waals Charge-Density-Wave Layer.

Kinks, point-like geometrical defects along dislocations, domain walls, and DNA, are stable and mobile, as solutions of a sine-Gordon wave equation. While they are widely investigated for crystal deformations and domain wall motions, electronic properties of individual kinks have received little attention. In this work, electronically and topologically distinct kinks are discovered along electronic domain walls in a correlated van der Waals insulator of 1T-TaS2 . Mobile kinks and antikinks are identified as trapped by pinning defects and imaged in scanning tunneling microscopy. Their atomic structures and in-gap electronic states are unveiled, which are mapped approximately into Su-Schrieffer-Heeger solitons. The twelvefold degeneracy of the domain walls in the present system guarantees an extraordinarily large number of distinct kinks and antikinks to emerge. Such large degeneracy together with the robust geometrical nature may be useful for handling multilevel information in van der Waals materialsarchitectures.

Особенности изменения структурно-морфологических свойств целлюлозы из бамбука при размоле

The wood of tropical plants, including bamboo, has great potential due to its rapid growth, simple cultivation, low cost, and characteristics suitable for the pulp and paper industry. The study considers the structural-morphological properties of unbleached kraft pulp from the wood of Bambusa blumeana, which grows in the Republic of Vietnam. Kraft cooking was carried out on an autoclave system, CAS 420. The obtained bamboo pulp had a yield of 41.7 %, the Kappa number was 17.3. Structural and morphological properties are determined by an automatic fiber analyzer, L&W Fiber Tester. Digital microphotographs were taken with an ImagerM2m Carl Zeiss microscope. Samples were studied before and after refining at the Yokro mill up to 60 °SR. A comparison of the change in the structural and dimensional properties of bamboo pulp fibers was made with industrial softwood and hardwood unbleached pulp. It has been established that, with a general, similar to hardwood and softwood pulp, the nature of the change in properties during refining – a decrease in the average fiber length (from 1.90 up to 1.21 mm), an increase in width (from 17.8 to 20.6 μm), shape factor (from 81.7 to 85.6 %), fines content (from 1.8 to 7.0 %), a decrease in the number of kinks per fiber (from 0,78 to 0,72), the average segment length (from 1.17 to 0.86 mm), also observed for softwood and hardwood pulp, the change in the values of the structural and dimensional characteristics of the fibers in pulp from bamboo occurs to the greatest extent. The reduced fiber width with a high fiber length provides the highest values of the fiber slenderness ratio l/w (from 106.6 for unrefined to 58.8 at 60 °SR) in comparison with softwood (from 81.3 to 60.6) and especially hardwood (from 44.4 to 36.0), which in turn leads to a reduced shape factor and easier damage to the fibers under hydromechanical action during refining, which is expressed in a change in the number of kinks on a fiber. The maximum changes in the structure, size, shape of the fiber and fine content occur already in the first 10 minutes of refining, which indicates the low strength of bamboo fibers and their easy damage. Therefore, it can be assumed that the use of unbleached bamboo pulp in brown paper furnishing will not lead to an increase in its strength. For citation: Khoa H.M., Kazakov Ya.V., Okulova E.O. Features of Changing Structural and Morphological Properties of Bamboo Pulp During Refining. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 146–159. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-146-159

Effect of calcium doping on the anodic behavior of E-AlMgSi (Aldrey) conducting aluminum alloy in NaCl electrolyte medium

The design of new materials intended for operation under severe conditions faces the task of rendering the materials corrosion resistant. The practical solution of this task is interrelated with the knowledge of corrosion protection of metals and alloys. The use of conducting aluminum alloys for the manufacture of thin wire may encounter specific problems. This is caused by the insufficient strength of these alloys and a small number of kinks before fracture. Aluminum alloys have been developed in recent years which even in a soft state have strength characteristics that allow them to be used as a conductive material. The E-AlMgSi (Aldrey) aluminum alloy is a well-known conducting alloy. This alloy is a heat-strengthened one, possessing good plasticity and high strength. After appropriate heat treatment this alloy acquires high electrical conductivity. Wires made from this alloy are almost exclusively used for air transmission lines. This work presents data on the corrosion behavior of calcium containing E-AlMgSi (Aldrey) aluminum conducting alloy in 0.03, 0.3 and 3.0% NaCl electrolyte medium. The anodic behavior of the alloy has been studied using a potentiostatic technique with a PI-50-1.1 potentiostat at a 2 mV/s potential sweep rate. Calcium doping of the E-AlMgSi (Aldrey) aluminum alloy increases its corrosion resistance by 15–20%. The corrosion, pitting and repassivation potentials of calcium doped alloys shift toward the positive region. An increase in the sodium chloride electrolyte concentration leads to a decrease in these potentials.

Effect of calcium doping on the anodic behavior of E-AlMgSi (Aldrey) conducting aluminum alloy in NaCl electrolyte medium

The design of new materials intended for operation under severe conditions faces the task of rendering the materials corrosion resistant. The practical solution of this task is interrelated with the knowledge of corrosion protection of metals and alloys. The use of conducting aluminum alloys for the manufacture of thin wire may encounter specific problems. This is caused by the insufficient strength of these alloys and a small number of kinks before fracture. Aluminum alloys have been developed in recent years which even in a soft state have strength characteristics that allow them to be used as a conductive material. The E-AlMgSi (Aldrey) aluminum alloy is a well-known conducting alloy. This alloy is a heat-strengthened one, possessing good plasticity and high strength. After appropriate heat treatment this alloy acquires high electrical conductivity. Wires made from this alloy are almost exclusively used for air transmission lines. This work presents data on the corrosion behavior of calcium containing E-AlMgSi (Aldrey) aluminum conducting alloy in 0.03, 0.3 and 3.0% NaCl electrolyte medium. The anodic behavior of the alloy has been studied using a potentiostatic technique with a PI-50-1.1 potentiostat at a 2 mV/s potential sweep rate. Calcium doping of the E-AlMgSi (Aldrey) aluminum alloy increases its corrosion resistance by 15–20%. The corrosion, pitting and repassivation potentials of calcium doped alloys shift toward the positive region. An increase in the sodium chloride electrolyte concentration leads to a decrease in these potentials.

Effect of ideal internal MHD instabilities on NBI fast ion redistribution in ITER 15 MA scenario

Transport of fast ions is a crucial issue during the operation of ITER. Redistribution of neutral beam injection (NBI) fast ions by the ideal internal magnetohydrodynamic (MHD) instabilities in ITER is studied utilizing the guiding-center code ORBIT (White R B and Chance M S 1984 Phys. Fluids 27 2455). Effects of the perturbation amplitude of the internal kink, the perturbation frequency of the fishbone instability, and the toroidal mode number of the internal kink are investigated, respectively, in this work. The internal kink mode can cause NBI fast ions transporting in real space from regions of to where labels the normalized plasma radial coordinate. The transport of fast ions is greater as the perturbation amplitude increases. The maximum relative change of the number of fast ions approaches 5% when the perturbation amplitude rises to 500 G. A strong transport is generated between the regions of and in the presence of the fishbone instability. Higher frequency results in greater transport, and the number of fast ions in is reduced by 30% at the fishbone frequency of 100 kHz. Perturbations with higher will lead to the excursion of fast ion transport regions outward along the radial direction. The loss of fast ions, however, is not affected by the internal MHD perturbation. Strong transport from to does not influence the plasma heating power of ITER, since the NBI fast ions are still located in the plasma core. On the other hand, the influence of fast ion transport from to needs further study.

Statistics of the number ofdefects after quantum annealing in a thermal environment.

We study the statistics of the kink number generated by quantum annealing ina one-dimensional transverse Ising model coupled to a bosonic thermal bath. Using the freezing ansatz for quantum annealing in the thermal environment, we show the relation between the ratio of the second to the first cumulant of the kink number distribution and the average kink density. The theoretical result is confirmed thoroughly by numerical simulation using the non-Markovian infinite time-evolving block decimation which we proposed recently. The simulation using D-Wave's quantum annealer is also discussed. This article is part of the theme issue 'Quantum annealing and computation: challenges and perspectives'.

Role of boundary conditions in the full counting statistics of topological defects after crossing a continuous phase transition

In a scenario of spontaneous symmetry breaking in finite time, topological defects are generated at a density that scale with the driving time according to the Kibble-Zurek mechanism (KZM). Signatures of universality beyond the KZM have recently been unveiled: The number distribution of topological defects has been shown to follow a binomial distribution, in which all cumulants inherit the universal power-law scaling with the quench rate, with cumulant rations being constant. In this work, we analyze the role of boundary conditions in the statistics of topological defects. In particular, we consider a lattice system with nearest-neighbor interactions subject to soft anti-periodic, open, and periodic boundary conditions implemented by an energy penalty term. We show that for fast and moderate quenches, the cumulants of the kink number distribution present a universal scaling with the quench rate that is independent of the boundary conditions except by an additive term, that becomes prominent in the limit of slow quenches, leading to the breaking of power-law behavior. We test our theoretical predictions with a one-dimensional scalar theory on a lattice.

Nonequilibrium chiral soliton lattice in the monoaxial chiral magnet MnNb3S6

In a magnetic superlattice composed of kinks in a ferromagnetic spin array, the change in the kink number requires the movement of the kinks to and from the crystal surface. Namely, the kinks must have a velocity, and the superlattice must be nonequilibrium. Evidence of the nonequilibrium state has never been observed in previous model compounds. In ${\mathrm{MnNb}}_{3}{\mathrm{S}}_{6}$, a long magnetization relaxation was observed, and the nature of the nonequilibrium state was more pronounced in the kink annihilation process rather than the kink creation process. The annihilation process can be phenomenologically reproduced using the unfrustrated magnetic clusters model. The nonequilibrium state in the annihilation process has a longer relaxation time than that in the nucleation process, since an energy barrier exists only in the latter.

Invariant subspaces and elliptic spin-helix states in the integrable open spin- 12 XYZ chain

We derive a criterion under which splitting of all eigenstates of an open $\mathrm{XYZ}$ Hamiltonian with boundary fields into two invariant subspaces, spanned by chiral shock states, occurs. The splitting is governed by an integer number, which has the geometrical meaning of the maximal number of kinks in the basis states. We describe the generic structure of the respective Bethe vectors. We obtain explicit expressions for Bethe vectors, in the absence of Bethe roots, and those generated by one Bethe root, and we investigate the single-particle subspace. We also describe in detail an elliptic analog of the spin-helix state, appearing in both the periodic and the open $\mathrm{XYZ}$ model, and we derive the eigenstate condition. The elliptic analog of the spin-helix state is characterized by a quasiperiodic modulation of the magnetization profile, governed by Jacobi elliptic functions.

RECYCLING OF WET-STRENGTH TISSUE PAPER. PART 2. BASIC PROPERTIES OF SECONDARY FIBERS

The present investigation focuses on morphological characteristics, tensile and optical properties of secondary fibers obtained in various conditions of batch low-consistency repulping process for wet-strength tissue paper with 100% of bleached softwood kraft pulp. It was found that length-weighted fiber length and fiber width values as well as fiber length and fiber width distributions remained almost unchanged regardless of the repulping time and the presence of persulfates. The shortened repulping cycle due to the use of persulfates lead to an increase in the shape factor from 83.0% to 84.1–84.4%, decrease in the number of fiber kinks from 0.84 to 0.72–0.74 and an increase in zero-span tensile strength of recycled handsheets by 10–12%. At the same time, the shortened repulping cycle resulted in increase in the coarseness of secondary fibers from 190 mg/m to 230–235 mg/m leading to a slight increase in the bulk of the paper and a decrease in its internal bond strength by an average of 8%. The use of persulfates during wet-strength tissue paper repulping improves the color of recycled handsheets and its brightness by up to 3%.

Initial state dependent dynamics across the many-body localization transition

We investigate quench dynamics across many-body localization (MBL) transition in an interacting one-dimensional system of spinless fermions with aperiodic potential. We consider a large number of initial states characterized by the number of kinks ${N}_{\mathrm{kinks}}$ in the density profile, such that the equal number of sites are occupied between any two consecutive kinks. We show that on the delocalized side of the MBL transition the dynamics becomes faster with increase in ${N}_{\mathrm{kinks}}$ such that the decay exponent $\ensuremath{\gamma}$ in the density imbalance increases with increase in ${N}_{\mathrm{kinks}}$. The growth exponent of the mean square displacement which shows a power-law behavior $\ensuremath{\langle}{x}^{2}(t)\ensuremath{\rangle}\ensuremath{\sim}{t}^{\ensuremath{\beta}}$ in the long-time limit is much larger than the exponent $\ensuremath{\gamma}$ for one-kink and other low-kink states though $\ensuremath{\beta}\ensuremath{\sim}2\ensuremath{\gamma}$ for a charge density wave state. As the disorder strength increases ${\ensuremath{\gamma}}_{{N}_{\mathrm{kink}}}\ensuremath{\rightarrow}0$ at some critical disorder, ${h}_{{N}_{\mathrm{kinks}}}$, which is a monotonically increasing function of ${N}_{\mathrm{kinks}}$. A one-kink state always underestimates the value of the disorder at which the MBL transition takes place but ${h}_{\text{1}\phantom{\rule{0.16em}{0ex}}\text{kink}}$ coincides with the onset of the subdiffusive phase preceding the MBL phase. This is consistent with the dynamics of interface broadening for the one-kink state. We show that the bipartite entanglement entropy has a logarithmic growth $aln(Vt)$ not only in the MBL phase but also in the delocalized phase and in both the phases the coefficient $a$ increases with ${N}_{\mathrm{kinks}}$ as well as with the interaction strength $V$. We explain this dependence of dynamics on the number of kinks in terms of the normalized participation ratio of initial states in the eigenbasis of the interacting Hamiltonian.

Effect of calcium additives on the anodic behavior of the conductive aluminum alloy E-AlMgSi (Aldrey) in the medium of the NaCl electrolyte

When creating new materials designed to work in particularly harsh conditions, the task of giving them corrosion resistance arises, the practical solution of which is associated with the level of knowledge in the field of high-temperature oxidation of metals and alloys. When using conductive aluminum alloys for the manufacture of thin wire, for example, winding wire, etc., certain difficulties may arise due to their insufficient strength and a small number of kinks before failure. In recent years, aluminum alloys have been developed, which even in a soft state have strength characteristics that allow them to be used as a conductor material. One of the conductive aluminum alloys is the E-AlMgSi alloy (Aldrey), which refers to thermally strengthened alloys. It is characterized by high strength and good ductility. This alloy under appropriate heat treatment acquires high electrical conductivity. The wires made from it are used almost exclusively for overhead power lines.The results of the study of the anodic behavior of the aluminum conductor alloy E-AlMgSi (Aldrey) with calcium, in an electrolyte medium of 0.03; 0.3 and 3.0% NaCl are presented. Corrosion-electrochemical study of alloys was carried out by the potentiostatic method on the PI-5.0-1.1 potentiostat at a potential sweep rate of 2 mV/s. It is shown that alloying the aluminum alloy E-AlMgSi (Aldrey) with calcium increases its corrosion resistance by 20%. The potentials of corrosion, pitting and repassivation of alloys during doping with calcium are shifted to the positive range of values, and from the concentration of sodium chloride in the negative direction of the ordinate axis.

Excitation of L-valine molecules by electrons and photons.

Excitation of L-valine molecules was studied by optical spectroscopy. Optical emission spectra of the L-valine molecule and optical excitation functions of molecular bands and the Hβ spectral line were measured in the gas phase using electron impact. In the spectra of optical emission in the wavelength range of 250–500 nm, intense emission bands were found at energies of incident electrons of 30, 50 and 70 eV. Analysis of structural features of the valine molecule suggested a fragmentation scheme with the formation of excited particles in collisions with electrons. A notable feature of the presented optical excitation functions is a different growth dynamics with an increase in the energy of exciting electrons and the presence of a number of features and kinks, which are especially pronounced for λ = 305 nm and λ = 311 nm. The excitation thresholds were determined from the initial sections of the excitation functions of the most intense spectral lines by the least-squares method. The photoluminescence spectra of L-valine were measured for the first time on a Shimadzu RF-6000 spectrofluorophotometer in the spectral range of 400–800 nm for excitation wavelengths of 250, 275, 333, 351, and 380 nm.Graphical abstract

Dark discrete breather modes in a monoaxial chiral helimagnet with easy-plane anisotropy

Nonlinearity and discreteness are two pivotal factors for an emergence of discrete breather excitations in various media. We argue that these requirements are met in the forced ferromagnetic phase of the monoaxial chiral helimagnet $\mathrm{Cr}{\mathrm{Nb}}_{3}\mathrm{S}{}_{6}$ due to the specific domain structure of the compound. The stationary, time-periodic breather modes appear as the discrete breather lattice solutions whose period mismatches with a system size. Thanks to easy-plane single-ion anisotropy intrinsic to $\mathrm{Cr}{\mathrm{Nb}}_{3}\mathrm{S}{}_{6}$, these modes are of the dark type with frequencies lying within the linear spin-wave band, close to its bottom edge. They represent cnoidal states of magnetization, similar to the well-known soliton lattice ground state, with differing but limited number of embedded $2\ensuremath{\pi}$ kinks. The linear stability of these dark breather modes is verified by means of Floquet analysis. Their energy, which is controlled by two parameters, namely, the breather lattice period and amplitude, falls off linearly with a growth of the kink number. These results may pave a path to design spintronic resonators on the base of chiral helimagnets.