Degree Of Twist Research Articles

Convective Magnetic Flux Emergence Simulations from the Deep Solar Interior to the Photosphere: Comprehensive Study of Flux Tube Twist

The emergence of magnetic flux from the deep convection zone plays an important role in solar magnetism, such as the generation of active regions and triggering of various eruptive phenomena, including jets, flares, and coronal mass ejections. To investigate the effects of magnetic twist on flux emergence, we performed numerical simulations of flux tube emergence using the radiative magnetohydrodynamic code R2D2 and conducted a systematic survey on the initial twist. Specifically, we varied the twist of the initial tube both positively and negatively from zero to twice the critical value for kink instability. As a result, regardless of the initial twist, the flux tube was lifted by the convective upflow and reached the photosphere to create sunspots. However, when the twist was too weak, the photospheric flux was quickly diffused and not retained long as coherent sunspots. The degree of magnetic twist measured in the photosphere conserved the original twist relatively well and was comparable to actual solar observations. Even in the untwisted case, a finite amount of magnetic helicity was injected into the upper atmosphere because the background turbulence added helicity. However, when the initial twist exceeded the critical value for kink instability, the magnetic helicity normalized by the total magnetic flux was found to be unreasonably larger than the observations, indicating that the kink instability of the emerging flux tube may not be a likely scenario for the formation of flare-productive active regions.

Degree of twist in the Achilles tendon interacts with its length and thickness in affecting local strain magnitude: a finite element analysis.

The relationship between the twisting of the three subtendons of the Achilles tendon (AT) and local strain has received attention in recent years. The present study aimed to elucidate how the degree of twist in the AT affects strain using finite element (FE) analysis, while also considering other geometries (e.g., length, thickness, and width) and their combinations. A total of 59 FE models with different degrees of twist and geometries were created. A lengthening force (z-axis) of 1,000N was applied to each subtendon (total: 3,000N). The average value of the first principal Lagrange strain was calculated for the middle third of the total length of the model. Statistical (stepwise) analysis revealed the effects of the degree of twist, other geometries, and their combinations on AT strain. The main findings were as follows: (1) a greater degree of twist resulted in higher average strains (t = 9.28, p < 0.0001) and (2) the effect of the degree of twist on the strain depended on dimensions of thickness of the most distal part of the AT (t = -4.49, p < 0.0001) and the length of the AT (t = -3.82, p = 0.0005). Specifically, when the thickness of the most distal part and length were large, the degree of twist had a small effect on the first principal Lagrange strain; however, when the thickness of the most distal part and length were small, a greater degree of twist results in higher first principal Lagrange strain. These results indicate that the relationship between the degree of twist and local strain is complex and may not be accurately assessed by FE simulation using a single geometry.

Determination of Velocities of Thread Axis Points When Interacting with a Direct Large Curvature Taking into Account the Deformation in the Contact Zone

The theoretical study of the process of the movement of the thread, which is deformed in the contact zone with the guide, from the point of view of determining the speed, is of great importance for solving a number of specific applied problems. When determining the speed, it was assumed that the start of the Lagrangian and Euler coordinates coincided. Taking into account that the crumpling of the thread in the contact zone occurs at forces much lower than the forces required to stretch the thread, the thread was considered as non-extensible. To determine the law of the distribution of the speed of the points of the thread, an independent vector, which is always connected to the main triangle, was introduced into consideration. The relationship between the vector of total curvature and the vector of absolute angular velocity is obtained. The obtained values of the speed at an arbitrary point of the axis of the thread as a function of the deformation vector, which determines the degree of twisting of the thread in the contact zone. The obtained results can be used to study various technological processes in the sewing, knitting, and textile industries, where the movement of the thread takes place along the guide surface of great curvature.

Tuning Two-Photon Absorption in Rhodopsin Chromophore via Backbone Modification: The Story Told by CC2 and TD-DFT.

We investigate here a systematic way to tune two-photon transition strengths (δ2PA) and two-photon absorption (2PA) cross sections (σ2PA) of the rhodopsin's chromophore 11-cis-retinal protonated Schiff base (RPSB) via the modulation of the methyl groups pattern along its polyene chain. Our team employed the resolution of identity, coupled cluster approximate second order (RI-CC2) method with Dunning's aug-cc-pVDZ basis set, to determine the structural impact on δ2PA, as well as its correlation to both transition dipole moments and permanent electric dipole moments. Seven structures were probed in vacuo, including five-double-bond-conjugated model of the native chromophore, shortened by the β-ionone ring (RPSB5), and its de/methylated analogues: 9-methyl, 13-methyl, planar and twisted models of 9,10-dimethyl and 9,10,13-trimethyl. Our results demonstrate that the magnitude of δ2PA is dictated by both the position and number of methylated groups attached to its polyene chain as well as the degree of dihedral twist that is introduced due to the de/methylation. In fact, a strong correlation between δ2PA enhancement and the presence of a C13-methyl group in the planar RPSB5 species is found. Trends in δ2PA values follow the trends observed in their corresponding changes in the permanent dipole moment upon the S0-S1 excitation nearly exactly. The assessment of four DFT functionals, i.e., M11, MN15, CAM-B3LYP, and BHandHLYP, previously found most successful in predicting 2PA properties in biological chromophores, points to a long-range-corrected hybrid meta-GGA M11 as the top-performing functional, albeit still delivering underestimated δ2PA and σ2PA values by a factor of 3.3-5.3 with respect to the CC2 results. In the case of global-hybrid meta-NGA (MN15), as well as CAM-B3LYP and BHandHLYP functionals, this factor deteriorates significantly to 6.7-20.9 and is mostly related to significantly lower quality of the ground- and excited-state dipole moments.

PROGNOSTIC FACTORS FOR ORCHIDECTOMY IN TESTICULAR TORSION PATIENTS AT TERTIARY HOSPITAL

Objective: This study was conducted to analyze the prognostic factors for orchidectomy in testicular torsion patients. Material &amp; Methods: From January 2001 to December 2021, 100 cases of testicular torsion cases were retrospectively collected. Data were described and analyzed based on clinical factors (age, duration of symptoms, scrotal swelling, high-riding testis, Prehn test, cremasteric reflex, leukocytosis, degree of twisting) and non-clinical factors (distance from hospital, duration of travel to hospital, education level and employment status) for each surgical procedure. Then logistic regression analysis was performed. Results: There were 88 testicular torsion patients (88%) underwent orchidectomy and 12 patients (12%) underwent orchidopexy. There was no significant relationship between age, duration of symptoms, scrotal swelling, Prehn test, cremasteric reflex, leukocytosis, distance from hospital, duration of travel to hospital, education level and employment status with orchidectomy (p&gt;0.05). Significant prognostic factors for orchidectomy in testicular torsion patients were high-riding testis (OR = 0.06; 95% CI = 0.01-0.37; p = 0.002) and degree of twisting (OR = 0.04; 95% CI = 0.006-0.24; p = 0.000). Conclusion: High-riding testis and degree of twisting are prognostic factors for orchidectomy in testicular torsion patients. Keywords: Orchidectomy, prognostic factors, testicular torsion.

Synergistic ductility deformation and helical design of carbon nanotube fiber composites

Twisting attracts more attention in adjusting the mechanical behavior and failure mechanism of materials, which could be implemented to understand and design the deformation behavior of helical structures. Herein, we developed a general helical model to theoretically investigate the mechanical response and geometric evolution of twisted carbon nanotube (CNT) fiber. The in-situ experimental results of CNT fibers in scanning electron microscopy were used to verify the correctness of the theory. For the structure with a large helical angle, the interfacial force and uncoordinated interlayer deformation during elongation are the key factors determining its unique tensile-torsional coupled motion. By helical design, the elongation and deformation of brittle fiber in composite structure can be delayed to achieve synergistic fracture with ductile fiber. The breaking order of these two fibers under stretching can be further regulated by changing the degree of twisting. Based on these theoretical results, the outer brittle fibers could also be used to predict the tensile necking and fracture locations of inner ductile materials. This approach can be achieved by changing the helical geometry and failure strain, and this work would throw light on the mechanical design of multi-layer cables and fiber composites.

Aeroelastic fluid dynamics assessment of performance and vibration on active twisting rotors

The effects of passive, and higher-harmonic rotor blade twist on helicopter main rotors are investigated. High-fidelity CFD is used for calculations due to the demanding flow conditions considered, including high blade loading, and high-speed cases. A strong structural coupling scheme is employed for enhanced performance and vibration predictions. Quantitative predictions are made for the effects of blade twist in hover, and the results showed: figure of merit improvements of up to 1 count per degree of twist, and diminishing returns with increasing twist. In high-speed level flight, the higher twist blade showed 18% increased vibration. A 2/rev active twist input shows vibration reductions of 22% in high-speed and 8% at high load cases. The active twist achieved a marginally improved aerodynamic efficiency at high-speed, and reduced the aerodynamic rolling moment in the dynamic stall conditions.

Left ventricular trabeculation in Hominidae: divergence of the human cardiac phenotype

Although the gross morphology of the heart is conserved across mammals, subtle interspecific variations exist in the cardiac phenotype, which may reflect evolutionary divergence among closely-related species. Here, we compare the left ventricle (LV) across all extant members of the Hominidae taxon, using 2D echocardiography, to gain insight into the evolution of the human heart. We present compelling evidence that the human LV has diverged away from a more trabeculated phenotype present in all other great apes, towards a ventricular wall with proportionally greater compact myocardium, which was corroborated by post-mortem chimpanzee (Pan troglodytes) hearts. Speckle-tracking echocardiographic analyses identified a negative curvilinear relationship between the degree of trabeculation and LV systolic twist, revealing lower rotational mechanics in the trabeculated non-human great ape LV. This divergent evolution of the human heart may have facilitated the augmentation of cardiac output to support the metabolic and thermoregulatory demands of the human ecological niche.

Semiconducting Polymers Based on Asymmetric Thiadiazoloquinoxaline for Augmented In Vivo NIR-II Photoacoustic Imaging.

A photoacoustic (PA) imaging technique using the second near-infrared (NIR-II) window has attracted more and more attention because of its merits of deeper penetration depth and higher signal-to-noise (S/N) ratio than that using the first near-infrared (NIR-I) one. However, the design and development of high-performance PA imaging contrast agents in the NIR-II window is still a challenge. A semiconducting polymer, constructed by asymmetric units, exhibits regiorandom characteristics that effectively increase the distortion of the backbone. This increase in the degree of twist can regulate the twisted intramolecular charge transfer (TICT) effect, resulting in an enhancement of the PA signal. In this paper, an asymmetric structural acceptor strategy is developed to improve the PA signals of the resulting semiconducting polymer (PATQ-MP) in the NIR-II window with improved brightness, higher S/N ratio, and better photothermal conversion efficiency compared to polymers with the same main-chain structure containing a symmetric acceptor. DFT analysis showed that PATQ-MP containing an asymmetric acceptor monomer had a larger dihedral angle, which effectively improved the PA signal intensity by enhancing the TICT effect. The PEG-encapsulated PATQ-MP nanoparticles exhibit promising performance in the PA imaging of mouse tumors in vivo, demonstrating the clear identification of microvessels as small as 100 μm along with rapid metabolism within a span of 5 h. Therefore, this work provides a unique molecular design strategy for improving the signal intensity of PA imaging in the NIR-II window.

Helitwistacenes – Combining Lateral and Longitudinal Helicity Results in Solvent‐Induced Inversion of Circularly Polarized Light

Helicity is expressed differently in ortho‐ and para‐fused acenes ‐ helicenes and twistacenes, respectively. While the extent of helicity is constant in helicenes, it can be tuned in twistacenes, and the handedness of flexible twistacenes is often determined by more rigid helicenes. Here, we combine helicenes with rigid twistacenes consisting of a tunable degree of twisting, forming helitwistacenes. While the X‐ray structures reveal that the connection does not affect the helicity of each moiety, their ECD and CPL spectra are strongly affected by the helicity of the twistacene unit, resulting in solvent‐induced sign inversion. ROESY‐NMR and TD‐DFT calculations support this observation, which is explained by differences in the relative orientation of the helicene and twistacene moieties.

Helitwistacenes-Combining Lateral and Longitudinal Helicity Results in Solvent-Induced Inversion of Circularly Polarized Light.

Helicity is expressed differently in ortho- and para-fused acenes-helicenes and twistacenes, respectively. While the extent of helicity is constant in helicenes, it can be tuned in twistacenes, and the handedness of flexible twistacenes is often determined by more rigid helicenes. Here, we combine helicenes with rigid twistacenes consisting of a tunable degree of twisting, forming helitwistacenes. While the X-ray structures reveal that the connection does not affect the helicity of each moiety, their electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) spectra are strongly affected by the helicity of the twistacene unit, resulting in solvent-induced sign inversion. ROESY NMR and TD-DFT calculations support this observation, which is explained by differences in the relative orientation of the helicene and twistacene moieties.

Triplet Excimer Formation in a DNA Duplex with Silver Ion-Mediated Base Pairs.

The dynamics of excited electronic states in self-assembled structures formed between silver(I) ions and cytosine-containing DNA strands or monomeric cytosine derivatives were investigated by time-resolved infrared (TRIR) spectroscopy and quantum mechanical calculations. The steady-state and time-resolved spectra depend sensitively on the underlying structures, which change with pH and the nucleobase and silver ion concentrations. At pH ∼ 4 and low dC20 strand concentration, an intramolecularly folded i-motif is observed, in which protons, and not silver ions, mediate C-C base pairing. However, at the higher strand concentrations used in the TRIR measurements, dC20 strands associate pairwise to yield duplex structures containing C-Ag+-C base pairs with a high degree of propeller twisting. UV excitation of the silver ion-mediated duplex produces a long-lived excited state, which we assign to a triplet excimer state localized on a pair of stacked cytosines. The computational results indicate that the propeller-twisted motifs induced by metal-ion binding are responsible for the enhanced intersystem crossing that populates the triplet state and not a generic heavy atom effect. Although triplet excimer states have been discussed frequently as intermediates in the formation of cyclobutane pyrimidine dimers, we find neither computational nor experimental evidence for cytosine-cytosine photoproduct formation in the systems studied. These findings provide a rare demonstration of a long-lived triplet excited state that is formed in a significant yield in a DNA duplex, demonstrating that supramolecular structural changes induced by metal ion binding profoundly affect DNA photophysics.

Fission Fragment Angular Momenta: Generation and Observation

The fission fragment angular momenta can generally be expressed in terms of the six normal modes of rotation for the dinucleus and different models populate those modes to different degrees reflecting the mechanisms involved. For the nucleon exchange mechanism, the characteristic time scales for the various modes are discussed, leading to the expectation that the wriggling mode is fully populated, while twisting is unlikely to play a major role; bending probably has some presence which increases with mass asymmetry. Subsequently it is discussed how information about the fragment spin directions can be determined by observation of E2 emissions in even-even nuclei. It is shown how the yield ratio Y (0°)/Y (90°) in a modern Wilhelmy-type experiment can reveal the degree of twisting, a measurement that could be readily carried out now. Furthermore, with a view towards the future when the required technology has been developed, it is illustrated how the relative role of positive modes (wriggling) and negative modes (bending and twisting) can be determined by measuring the opening angle between two E2 photons whose helicities are also identified.

Analysis of factors associated with delayed diagnosis and treatment of testicular torsion in 1005 cases from Chongqing city, China: a cross-sectional study

This study aimed to investigate the clinical and social factors of delayed treatment for testicular torsion (TT) and to explore the risk factors of testicular excision in China. The clinical data of 1005 patients with TT who were admitted to 48 medical institutions in Chongqing city (China) from January 2012 to December 2021 were retrospectively analyzed. It was revealed that the misdiagnosis rates of non-senior (junior and middle) grade doctors and senior doctors were 25.1% and 9.6%, respectively. The proportion of TT patients who received timely treatment (within 6 h after onset of symptoms) was 23.8%. The results of the multivariable logistic regression analysis indicated that absent cremasteric reflex was a protective factor for delayed surgery of more than 6 h from onset of symptoms to surgery. Misdiagnosis, consultation with a non-urologist as the first consultant doctor, absence blood flow in color Doppler ultrasound, negative high-riding testis findings, the presence of fever, and non-manual detorsion were identified as risk factors associated with delayed surgery (more than 6 h from the onset of symptoms) for TT. Furthermore, misdiagnosis, non-urologist first-consultant doctor, absent blood flow in DUS, non-manual detorsion, fever, degree of cord twisting > 180, and the initial diagnosis in tertiary hospitals were risk factors for orchidectomy. Having TT on the right side, and the presence of nausea and vomiting were identified as protective factors for orchidectomy. Technical training in the diagnosis and treatment of TT should be extended to primary hospitals and doctors to significantly improve their accuracy in managing this condition.

Low-Grade Injury following Testicular Torsion: A Multicenter Study Confirming a Disturbing Possibility

Introduction: There is an ongoing debate whether to perform orchiectomy or orchidopexy following testicular torsion (TT) in cases where the testis seems non-viable. The main problem is lack of objective criteria defining testicular viability. The aim of this study was to investigate the grade of injury in orchiectomy specimens obtained from cases of TT and its association with clinical findings. Methods: This multicenter retrospective study involved double-blinded reassessment of the patient files and the pathological specimens using Mikuz classification to analyze the relation between clinical and pathological findings. Results: A total of 289 patient charts from 14 centers were reviewed and 228 were included in this study. Twenty (8.8%) patients had grade 1 injury which refers to reversible injury. The clinical findings of these 20 patients were compared to 208 patients with higher grades of injury. As expected, there was statistically significant difference regarding duration of symptoms (p < 0.001); however, range was wide in both groups (as long as 96 h for grade 1 and as short as 7 h for higher grades). There was no statistically significant difference in any other variable including age (median 14 for both, p = 0.531), symptoms (pain: 19/20 vs. 189/202, p = 0.801; swelling: 13/19 vs. 168/197, p = 0.094), absence of blood flow in Doppler US (15/19 vs. 164/197, p = 0.635), or degree of torsion (median 720° for both, p = 0.172). Conclusion: Our study revealed necessity for better criteria to define viability of testis following TT. Histopathological injury appeared to be reversible even in some patients with more severe perioperative findings, late admission, or high degree of twisting. Our findings support the tendency for testicular fixation instead of orchiectomy as none of the clinical or perioperative findings could be attributed to high-grade injury.

Simultaneous 2.25/8.60 GHz Observations of the Magnetar XTE J1810-197

We did 194 epochs of simultaneous 2.25/8.60 GHz observations of XTE J1810−197 in 926 days shortly following its reactivation in 2018 with Shanghai Tian Ma Radio Telescope (TMRT). Although its integrated profiles changed with both time and frequency during this period, they could be classified into 12 types according to phase areas of active radiation components. After MJD 59015, XTE J1810−197 turned from the normal emission state into the spiky emission state that was manifesting as a series of bright narrow sub-pulse bursts at both 2.25 and 8.60 GHz. Due to its variable integrated profiles and unsteady rotations, we got the spin frequency ν and spin-frequency derivatives with the piecewise fitting method. In addition, its long-term declining trend of ν was also obtained as s−2 with the linear fitting method based on our observations spanning a comparatively longer period. We found its flux densities went through three stages: sharp decrease, stabilization, and day-to-day fluctuations in our dual-frequency observations. Although the flux density showed different stages, XTE J1810−197 showed a relatively flat spectrum (α > –1) in most observations. Assuming an ideal dipole magnetic field as some previous research works, we obtained the emission heights of XTE J1810−197 were about 7.5(9) × 104 km and 2.38(7) × 104 km at 2.25 and 8.60 GHz, respectively. We also found that its emission heights would decrease rapidly with the degree of magnetic field twisting.

Modification of Meso-Micromixing Interaction Reaction Model in Continuous Reactors

The yields of chemical reactions are highly dependent on the mixing pattern between reactants. Herein, we report the modification of a meso-micromixing interaction reaction model which is applied in batch reactors by leveraging the flow characteristics in the continuous reactors. Both experimental and model-predicted yields were compared using the classical Villermaux–Dushman method in a self-designed split and recombination reactor. This modified model significantly reduced the error in predicted product yields from approximately 15% to within 3%, compared to a model containing the micromixing term only. The effects of flow rates and reactor structure parameters on mixing performance were analyzed. We found that increasing flow rates and the degree of twist in the mixing element’s grooves, as well as decreasing the cross-sectional area of grooves, improved mixing performance. The optimization of reactor flow rates and structural parameters was achieved by combining Gaussian process regression and Bayesian optimization with the modified model. This approach provided higher target product yields for consecutive reactions, while simultaneously achieving a lower pressure drop in the reactor. Corresponding combinations of reactor parameters were also identified during this process. Our modified model-based optimization methodology can be applied to a diversity of reactors, serving as a reference for the selection of their structure and operational parameters.

Situation of Pediatric Patients with Testicular Torsion in Times of COVID-19.

To assess whether the COVID-19 pandemic had an influence on presentation of testicular torsion and/or increase in the frequency of orchiectomy. Patients and Methods. This retrospective study included boys under 18 years of age with testicular torsion divided in two groups: pre-COVID operated in 2019 vs. COVID-19 group from 2020. We compared demographic data as well as local and general symptoms. We analyzed additional tests, intraoperative findings, length of operation and hospitalization, and followup. Results. We analyzed the data collected from 44 patients (24 boys from first group vs. 20 boys from second group). The median age was 13.4 years vs. 14.5 years in the latter. The median time of symptoms duration was 6.5 hours and 8.5 hours, respectively. The main manifestation was testicular pain without additional signs. The results of the laboratory tests did not reflect local advancement. In the 2019 group, Doppler ultrasound showed absent blood flow in the affected testicle in 62% vs. 80% in 2020. The mean time from admission to surgery was virtually identical: 75 minutes in 2019 vs. 76 minutes in 2020. The mean duration of scrotal revision was similar in both groups. There was only one significant difference: the degree of twisting. In 2019, the mean was 360° vs. 540° in 2020. Incidence of orchiectomy also did not significantly vary between the analyzed time periods, with 21% during the pandemic and 35% during the pre-COVID-19 period. Conclusion. We did not observe an increase in the number of testicular torsion cases during the COVID-19 pandemic. Most importantly, the rates of orchiectomy did not significantly differ between the patients with testicular torsion presenting during the COVID-19 outbreak.

RESEARCH OF THE AERODYNAMIC PROCESS OF CARBON DUST REMOVAL FROM THE WORKING ZONE

The purpose of this work is research of the aerodynamic process of carbon dust removal from the working zone in order to create safe and harmless working conditions at the production site. As a result of the research, an aerodynamic calculation of a long air duct of uniform suction with tangential air intake was performed. The degree of twisting of the air flow inside the air duct, as well as the uniformity of air suction along the length of the long suction, were determined. A number of factors affecting the dust removal process have been established, such as suction torch long suction; coefficient of local suction resistance; forces of inertia and viscosity on the resistance of local suction. The dependence of the ratio of the width of the entrance hole to the diameter of the air duct on the local suction resistance, the dependence of the ratio of the areas of the entrance gap and the cross section of the transitional air duct on the local suction resistance, as well as the effect of the length of the entrance slot on the coefficient of local suction resistance were determined. The efficiency of suction of dust particles with an extended suction unit with tangential air entry has been proven. For a more accurate analysis of the distance at which an extended extractor with tangential air intake can be placed relative to the dust source, it is necessary to conduct a dispersed dust analysis. For effective capture of specific dust, calculations should be based on the size of the dust, which occupies a larger share in the distribution of fractions. The smaller the dust particle, the further the suction device can be located. To visualize the experimentally obtained results, simulation was performed in the FlowVision software in accordance with the mathematically calculated initial data. During the simulation of the movement of dusty air in an extended extractor with a tangential entry into the system, the occurrence of swirling of the air flow has been proven. Due to this formation, the largest fractions of dust will move along the walls of the air duct. This makes it possible to use extended extractors to remove coarse fractions of dust contained in polluted air, organizing the removal of air moving near the walls of the air duct. Keywords: carbon dust, aerodynamic calculation, engineering simulation, occupational diseases, occupational health.

Energetic preference and topological constraint effects on the formation of DNA twisted toroidal bundles.

DNA toroids are compact torus-shaped bundles formed by one or multiple DNA molecules being condensed from the solution due to various condensing agents. It has been shown that the DNA toroidal bundles are twisted. However, the global conformations of DNA inside these bundles are still not well understood. In this study, we investigate this issue by solving different models for the toroidal bundles and performing replica-exchange molecular dynamics (REMD) simulations for self-attractive stiff polymers of various chain lengths. We find that a moderate degree of twisting is energetically favorable for toroidal bundles, yielding optimal configurations of lower energies than for other bundles corresponding to spool-like and constant radius of curvature arrangements. The REMD simulations show that the ground states of the stiff polymers are twisted toroidal bundles with the average twist degrees close to those predicted by the theoretical model. Constant-temperature simulations show that twisted toroidal bundles can be formed through successive processes of nucleation, growth, quick tightening, and slow tightening of the toroid, with the two last processes facilitating the polymer threading through the toroid's hole. A relatively long chain of 512 beads has an increased dynamical difficulty to access the twisted bundle states due to the polymer's topological constraint. Interestingly, we also observed significantly twisted toroidal bundles with a sharp U-shaped region in the polymer conformation. It is suggested that this U-shaped region makes the formation of twisted bundles easier by effectively reducing the polymer length. This effect can be equivalent to having multiple chains in the toroid.