Torsional Rotation Research Articles

Three-Dimensional Analysis Versus Two-Dimensional Slice-Based Analysis of CT for Measuring Femoral Torsion and Its Correlation to Passive Hip Range of Motion.

IntroductionFemoral torsion is an important anatomical consideration of the hip that has major implications on the natural motion of the hip joint. Similarly, it affects pathologic conditions of the hip, including femoroacetabular impingement, dysplasia, and/or microinstability. Femoral torsion is typically measured on two-dimensional (2D) axial CT cuts by creating the angle between the femoral neck and the posterior aspect of the ipsilateral femoral condyles. Position of the leg during imaging may affect 2D measurements. Three-dimensional (3D) analysis of a hip CT with inclusion of femoral alignment may portray the anatomy of the hip more accurately as compared to a 2D slice-based analysis of a hip CT scan. It is thought that femoral torsion measured using this system could be a more accurate and reliable means of measurement. The primary purpose of this study is to assess the differences in measuring femoral torsion with 3D modeling and analysis compared to the standard 2D slice-based approach on a CT scan. Secondarily, we attempt to determine how the passive range of motion of the hip correlates with femoral torsion measured using the 3D model versus the 2D model.MethodsIn a prospective cohort study of 20 patients, femoral torsion was assessed using both 2D analysis and 3D analysis. The differences between these measurements on each of the imaging modalities were compared. Additionally, each patient had the passive range of motion of their hip measured with a goniometer. The amount of internal and external rotation was measured with the hip in a neutral position and with the hip flexed to 90°. Acetabular version, combined version, and alpha angle were added to multivariate regression analysis to evaluate their effect versus femoral torsion alone.ResultsFemoral antetorsion measured using the standard 2D slice-based approach on CT scan was 22.1° (SD: 11.1°), which was higher (p<0.001) than that using 3D analysis (8.25°; SD: 10.5°). There was a strong correlation between femoral torsion measurements using 3D analysis and 2D analysis (R=0.91). Based on 3D analysis, there was a moderate correlation between femoral torsion and passive hip external rotation measured with the hip flexed to 90° (R=0.65, p<0.002) and with the hip in a neutral position (R=0.58, p<0.007).ConclusionThere was a significant difference between femoral torsion measurements using the 3D analysis, which showed approximately 14° of less antetorsion on average. Additionally, rotation of the hip and femoral torsion was correlated to higher levels of antetorsion associated with more internal rotation of the hip.

Morphology modulation of artificial muscles by thermodynamic-twist coupling.

Human muscles can grow and change their length with body development; therefore, artificial muscles that modulate their morphology according to changing needs are needed. In this paper, we report a strategy to transform an artificial muscle into a new muscle with a different morphology by thermodynamic-twist coupling, and illustrate its structural evolution during actuation. The muscle length can be continuously modulated over a large temperature range, and actuation occurs by continuously changing the temperature. This strategy is applicable to different actuation modes, including tensile elongation, tensile contraction and torsional rotation. This is realized by twist insertion into a fibre to produce torsional stress. Fibre annealing causes partial thermodynamic relaxation of the spiral molecular chains, which serves as internal tethering and inhibits fibre twist release, thus producing a self-supporting artificial muscle that actuates under heating. At a sufficiently high temperature, further relaxation of the spiral molecular chains occurs, resulting in a new muscle with a different length. A structural study provides an understanding of the thermodynamic-twist coupling. This work provides a new design strategy for intelligent materials.

On the Modelling of “Fork” Supports Using geometrically Exact Thin‐walled Beam Finite Elements

AbstractThis paper discusses issues related to the modelling of so‐called “fork” supports using geometrically exact 3D thin‐walled beam finite elements whose rotations are parametrized using the rotation vector. This study is motivated by the fact that isolated members with “fork” supports are commonly employed in numerical and experimental studies, for the development of design rules for steel members. These supports are defined in the small displacement range, restraining the cross‐section in‐plane displacements and the torsional rotation of the beam (along the beam initial axis). This definition is usually extended to the large displacement case for beam finite element models, whereas in experimental tests and shell finite element models, a two‐axis gimbal‐type support is used instead. This paper thus aims at (i) showing how the two‐axis gimbal support may be modelled using beam elements which are based on a rotation vector parametrization of finite rotations and (ii) highlighting the differences between the two support types. Numerical examples are presented to illustrate the differences, which are quite significant for moderate‐to‐large displacements, but do not seem to affect the collapse load of standard steel members.

The torsion–rotation spectrum of deuterated hydrogen peroxide HOOD — The first torsional state

We measured the spectrum of singly deuterated hydrogen peroxide HOOD at the synchrotron facility SOLEIL in the infrared region from 6.3 up to 500 cm−1 to investigate the first torsional excited state n=1 and to determine the size of the torsional splitting near the trans tunneling barrier of the molecule. Due to the dense and perturbed spectrum, an automatic assignment algorithm (ASAP) was used to analyze it in addition to Colin Western’s PGOPHER software. We succeeded to assign 3704 ro-torsional transitions from the ground state to the first torsional state and determined accurate experimental band origins as well as rotational constants. This allowed us to derive the Ka- and J-dependence of the torsional splitting.

The Biomechanical Profile of an Osseo-Integrated Rectangular Block Implant: A Pilot In Vivo Strain Analysis

Aim: To load-test the osseo-integrated rectangular block implant (RBI), measure the generated cortical peri-implant strains, and relate these findings to known human physiological parameters. Materials and methods: Two RBIs were placed into the posterior mandibular saddle in a mature greyhound dog and allowed to osseo-integrate. The half mandible (implants in situ) was mounted in a servohydraulic system. Four triple-stacked rosette gauges were placed cortically (mesial, distal, buccal, and lingual). A modified ISO-14801 protocol was used (1000 N, 300, 2 Hz, 1 h) and the generated principal strains (ep, eq) and their angular orientations (F), were calculated. Results: (1) Bucco-lingual “horizontal” dimension: dominant “horizontal” compressive stresses were on the lingual aspect and “horizontal” tensile stresses on the buccal aspect. The buccal cortex was elastically tensile-stretched, while the lingual cortex was elastically compressed. (2) Bucco-lingual “vertical” dimension: dominant vertical torsional stresses were oriented buccally and apically, with an overall buccally inclined torsional effect. This was also evidenced on the lingual aspect, where there remained high torsional rotation elements (high F and e2). (3) Mesio-distal “horizontal” dimension: dominant torsional stresses oriented as a distal-lingual “counter-clockwise” rotation. Conclusions: The applied off-axial loads generated a heterogeneous pattern of bucco-lingual and mesio-distal cortical strains, both vertically and horizontally. The short dimensioned osseo-integrated RBI design appeared to biomechanically withstand the applied loads and to maintain the strains generated to levels that were within physiological limits. More studies and statistical analyses are needed to confirm these findings.

Real-time correction of image rotation with adaptive optics scanning light ophthalmoscopy.

Fixational eye motion includes typical translation and torsion. In the registration of images from adaptive optics scanning light ophthalmoscopy (AOSLO), image rotation due to eye torsion and/or head rotation is often ignored because (a) the amount of rotation is trivial compared to translation within a short duration of imaging or recording time and (b) computational cost increases substantially when the registration algorithm involves simultaneous detection of rotation and translation. However, it becomes critically important under cases such as long exposure, functional measurements, and precise motion tracking. We developed a fast method to detect and correct rotation from AOSLO images, together with the detection of strip-level motion translation. The computational cost for rotation detection and correction alone is about 5 ms/frame (512×512 pixels) on an nVidia GTX960M GPU. Image quality is compared with and without rotation correction from 10 healthy human subjects and 8 diseased eyes with a total of 180 videos. The results show that residual image motions between the reference images and the registered images with rotation correction are a fraction of those without rotation correction, and the ratio is 0.74-0.89 at the image center and 0.37-0.51 at the four corners of the images.

Influence of tooth crack parameters on bearing vibration signal of a geared rotor

Fault diagnosis is a mandatory process in modern industry management, because it may reduce costs due to unexpected failures that may occur in machines. It is proposed to study the dynamic effect in the rotor response of gear tooth crack caused by bending stress. As the bearings are the common location to install sensors as accelerometers, the response in their corresponding degrees of freedom is considered. A geared rotor model is assumed for the simulations. This model embraces a detailed finite element discretization, which contemplates five degrees of freedom per node, including torsional rotation. In addition, a time-varying mesh stiffness calculated by the potential energy method is adopted to represent the tooth contact. A crack model is assumed with three input parameters (initial position, propagation angle and depth). A design of experiments was set up to show the influence of each parameter on the system response for three different mean depths. The results analysis pointed out that for a precise parameter identification, all three parameters should be taken into account, because they affect the system response and they also present combined influence.

Tunneling motion and splitting in the CH2OH radical: (Sub-)millimeter wave spectrum analysis.

The (sub-)millimeter wave spectrum of the non-rigid CH2OH radical is investigated both experimentally and theoretically. Ab initio calculations are carried out to quantitatively characterize its potential energy surface as a function of the two large amplitude ∠H1COH and ∠H2COH dihedral angles. It is shown that the radical displays a large amplitude torsional-like motion of its CH2 group with respect to the OH group. The rotation-torsion levels computed with the help of a 4D Hamiltonian accounting for this torsional-like motion and for the overall rotation exhibit a tunneling splitting, in agreement with recent experimental investigations, and a strong rotational dependence of this tunneling splitting on the rotational quantum number Ka due to the rotation-torsion Coriolis coupling. Based on an internal axis method approach, a fitting Hamiltonian accounting for tunneling effects and for the fine and hyperfine structure is built and applied to the fitting of the new (sub)-millimeter wave transitions measured in this work along with previously available high-resolution data. 778 frequencies and wavenumbers are reproduced with a unitless standard deviation of 0.79 using 27 parameters. The N = 0 tunneling splitting, which could not be determined unambiguously in the previous high-resolution investigations, is determined based on its rotational dependence.

Synthesis, photophysical behavior in solution, aggregates, solid state and computational study of new derivatives of 2,2′-bis(indolyl)methane-triphenylamine

A series of new 2,2′-bis(indolyl)methane-triphenylamine (2,2′-BIM-TPA) derivatives were synthesized and characterized. TPA units were inserted in the indole fragment, as well as in the methylene position of the BIM to obtain systems with a high degree of torsion and intramolecular rotation. Phenyl and phenylethynyl linkers between TPA and BIM units were included in the BIM-Ph-TPA and BIM-Ph-E-TPA derivatives to extend the conjugation of the methylene substituted BIMs. The absorption and emission behavior in solution, aggregates and solid state of five 2,2′-BIM-TPA derivatives was studied. Only BIM-Ph-TPA and BIM-Ph-E-TPA showed a slight solvatochromic behavior. In THF-water mixtures, non-emissive aggregates were produced, but the concentrated solutions (1000 µM) of each compound favored the formation of emissive aggregates. It was found that water acts as a fluorescence quencher of the aggregates. Additionally, the 2,2′-BIM-TPA derivatives showed fluorescence in the solid state. The DFT computational studies allowed to confirm the highly twisted molecular geometries, to elucidate the distribution and energy of the frontier molecular orbitals (HOMO-LUMO), as well as the nature of the main electronic transitions (UV–Vis).

Exploration of the effect of wing component post-buckling on bending-twist coupling for nonlinear wing twist

A new investigated concept for passive load alleviation is to exploit the nonlinear behavior of wing design components to trigger a deformation which reduce loads once a critical load level is reached. The necessary deformation is a torsional rotation which is supposed to reduce the angle of attack. For this target, wingbox sections are investigated regarding their nonlinear behavior with finite element analysis. Parameter studies feature anisotropic carbon fiber reinforced polymer (CFRP) layups for the skins, layups and thicknesses for spars and the presence of stringers. Results show a desired nonlinear progressive bending-torsion coupling for an unstiffened wingbox section, when the upper skin and the rear spar are modified. After modification they are allowed to buckle within the load envelope. The skin has an anisotropic layup. The rear spar needs to be thinner than the front spar. Both modifications result in progressively increasing torsional rotation of the wingbox with increasing load. Stringers are not applied because they limit the nonlinearity which is not desired for the envisioned load alleviation technique.

Enhancing Ligand and Protein Sampling Using Sequential Monte Carlo.

The sampling problem is one of the most widely studied topics in computational chemistry. While various methods exist for sampling along a set of reaction coordinates, many require system-dependent hyperparameters to achieve maximum efficiency. In this work, we present an alchemical variation of adaptive sequential Monte Carlo (SMC), an irreversible importance resampling method that is part of a well-studied class of methods that have been used in various applications but have been underexplored in computational biophysics. Afterward, we apply alchemical SMC on a variety of test cases, including torsional rotations of solvated ligands (butene and a terphenyl derivative), translational and rotational movements of protein-bound ligands, and protein side chain rotation coupled to the ligand degrees of freedom (T4-lysozyme, protein tyrosine phosphatase 1B, and transforming growth factor β). We find that alchemical SMC is an efficient way to explore targeted degrees of freedom and can be applied to a variety of systems using the same hyperparameters to achieve a similar performance. Alchemical SMC is a promising tool for preparatory exploration of systems where long-timescale sampling of the entire system can be traded off against short-timescale sampling of a particular set of degrees of freedom over a population of conformers.

Selection of the optimal diagrid patterns in tall buildings within a multi-response framework: Application of the desirability function

Diagrids are efficient structural systems for tall building design and construction due to their high lateral stiffness. Their structural response can be optimized by changing the geometrical pattern of external diagonals. This has usually been carried out by looking for the diagonal pattern that employs the minimum amount of structural material, while complying with strength and stiffness requirements. However, other responses can be significant for the selection of the optimal pattern, such as the torsional flexibility and construction complexity of the building. In this work, the desirability function approach has been used for selecting the optimal diagonal pattern for diagrid tall buildings in a multi-response framework. The most desirable diagonal layout has been selected based on its overall desirability to minimize: (i) the wind-induced lateral displacement, (ii) the torsional rotation, (iii) the diagrid structural weight, and (iv) the construction complexity. The application of this methodology straightforwardly provides the optimal diagrid pattern considering the four responses simultaneously. The method has been applied initially to a limited set of uniform-angle patterns, and afterwards to a wider population of varying-angle geometries. Four different floor plan shapes were also taken into account. The outcomes of the analysis revealed that the specific plan shape plays only a minor role in the definition of the optimal structure, whereas the diagonal layout affects greatly the efficiency of the solution. Uniform-angle diagrids are generally the most desirable, even for taller buildings, due to their higher performance in terms of torsional rigidity and construction complexity. Among these, the patterns in which the diagrid triangular module spans over two-three floors, corresponding to diagonal inclinations of about 55°–65°, have the highest desirability. Notably, because of the competition between the different responses, this optimal inclination is not found to increase as the building becomes taller.

Spectroscopic and theoretical studies of some 2-(2′-ethylsulfanyl)acetyl-5-substituted furans and thiophenes

The conformational equilibrium of 2-(2′-ethylsulfanyl)acetyl-5-substituted furans and thiophenes [EtSCH2C(O)(C4H2X)Y] (1–5; Scheme 1) was determined through the infrared analysis of the carbonyl stretching band (νCO) supported by DFT (B3LYP/aug-cc-pVTZ) and molecular dynamics simulations (OPLS-AA). Six stable conformations, syn(1–3) and anti(1–3), were obtained through the optimisation of the isolated systems, where the syn/anti nomenclature refers to the dihedral angle between the carbonyl and the aromatic heteroatom (O=C–C–X; X = O, S) and 1, 2, and 3 refer to the ethyl rotation (Scheme 2) (torsion around the γ dihedral angle). The three ethyl conformers resemble six- (1 and 2) or seven-(3) member pseudo-rings with an electrostatic intramolecular hydrogen bond (Oδ-···Hδ+). The IR spectra in solution show νCO doublets for all compounds in all solvents (n-C6H14, CCl4, CHCl3, CH2Cl2 and CH3CN). The polarisable continuum model and molecular dynamics data allow the lowest wavenumber and more intense νCO IR component to be ascribed to the three anti conformers of the furan derivatives and to the three syn ones of the thiophene compounds. The conformational preferences of all compounds are governed by a balance between orbital and coulombic interactions, as estimated by means of natural bond orbital, natural coulomb electrostatic, pairwise steric exchange energy, quantum theory of atoms in molecules, non-covalent interaction and short-contact analyses. While the conformational isomerism of the ethylthioacetyl moiety is determined by both quantum and columbic effects, the equilibrium involving the carbonyl and heterocyclic moiety is controlled largely by electrostatic interactions.

Simulating the growth of amorphous organic thin films

Physical vapor deposition is used widely to produce organic electronics devices, in particular for OLEDs in smartphones, TVs and other display applications. Despite its long history, recent years have seen a number of surprising observations, such as deposition-induced emitter orientation and built-in electrostatic potentials in thin organic films. Modeling the details of these effects is complicated by the long time scales involved in the underlying processes. In this paper, we compare two different modeling approaches, which both aim to simulate the physical vapor deposition (PVD) process for small organic molecules. We compare a molecular dynamics approach, based on a classical bead-spring force field and time integration, with a Metropolis Monte Carlo approach, where the intramolecular degrees are limited to the torsional rotations. To analyze the resulting structures, we calculate the density and radial distribution functions (RDF) of all films. We observe a good agreement for the RDFs, but an approximately 10% higher density for the films generated by the molecular dynamics approach. Additionally, we investigate the anisotropic nature of such morphologies by calculating the ordinary and extra-ordinary refractive index for each material. Finally, we calculate electron and hole mobilities with an Kinetic Monte Carlo protocol.

Experimental analysis of tip vibrations at higher eigenmodes of QPlus sensors for atomic force microscopy

QPlus sensors are non-contact atomic force microscope probes constructed from a quartz tuning fork and a tungsten wire with an electrochemically etched tip. These probes are self-sensing and offer an atomic-scale spatial resolution. Therefore, qPlus sensors are routinely used to visualize the chemical structure of adsorbed organic molecules via the so-called bond imaging technique. This is achieved by functionalizing the AFM tip with a single CO molecule and exciting the sensor at the first vertical cantilever resonance mode. Recent work using higher-order resonance modes has also resolved the chemical structure of single organic molecules. However, in these experiments, the image contrast can differ significantly from the conventional bond imaging contrast, which was suspected to be caused by unknown vibrations of the tip. This work investigates the source of these artefacts by using a combination of mechanical simulation and laser vibrometry to characterize a range of sensors with different tip wire geometries. The results show that increased tip mass and length cause increased torsional rotation of the tuning fork beam due to the off-center mounting of the tip wire, and increased flexural vibration of the tip. These undesirable motions cause lateral deflection of the probe tip as it approaches the sample, which is rationalized to be the cause of the different image contrast. The results also provide a guide for future probe development to reduce these issues.

Ultrasound Visualization of Torsional Anatomic Changes in the Neck

Introduction: The objective of this paper is to demonstrate changes in the sonographic appearance of muscles in region of the neck with cervical movement from neutral anatomic position to right rotational torsion. Methods: Sonographic images were obtained in a 56-year-old healthy female. Muscles selected are common targets for botulinum toxin A injection in treatment for cervical dystonia. Sonographic images were obtained with the transducer placed over the muscle of interest with the neck in both anatomic-neutral and right-rotated positions. Cine loop video was also recorded at each site to track muscles throughout torsion. Results: The results show that in rotational torsion, (1) the brachial plexus becomes difficult to view due to anisotropy when examining the scalenes. The relationship between the anterior and middle scalenes and brachial plexus becomes less distinct with cervical rotation beyond neutral position. (2) The positional relationship of the sternocleidomastoid (SCM) and the ipsilateral splenius capitus is altered. (3) The jugular vein changes from collapsed to distended in the contralateral SCM view. (4) The position of the trapezius is not altered significantly. Conclusion: The sonographic appearance of soft tissue structures about the neck differs significantly with cervical movement from an anatomic neutral position to a position of right torsion. Knowledge of the dynamic positional changes of the muscles in this region in relation to each other, as well as the neurovascular structures, with cervical movement and torsion can potentially improve diagnostic assessment as well as accuracy of interventional procedures.

Analysis of bending-twisting coupling in angle-ply laminates

The purpose of the present study is the evaluation of the bending-twisting coupling effect in the analysis of the DCB test by means of the analytical determination of the energy release rate of angle-ply laminated composites. The aim is to extend a previous work done by the same authors to new laminate configurations. Angle-ply laminates with symmetrical arms are analyzed, since in this case the application of a bending moment by means of the piano hinges causes a torsional rotation in each of the arms. That torsion is prevented by the hinges, due to the configuration of the test. Therefore, there is a non-uniform load distribution applied by the hinges, whose resultant is the applied load P and the resultant moment is an unknown twisting moment mt, which prevents rotation at the point of application. The resolution of the resulting system of forces and moments allows obtaining analytically the energy release rate, and analyzing the terms due exclusively to the bending-twisting coupling.

Investigation of the Relationship Between Hip and Knee Osteoarthritis and Disordered Spinal and Pelvic Morphology.

IntroductionA critical question is the causal relationship between hip or knee osteoarthritis (OA) and disordered spinal and pelvic morphology. The aim of this study is to examine this correlation. Therefore, we studied the effect of total hip or knee arthroplasty (THA/TKA) on truncal parameters to determine the causal relationship between these two situations.Materials and methodsThis is a prospective study of the effect of THA or TKA in patients with hip or knee OA on truncal morphological parameters. Patients with one-sided hip or knee OA who chose to undergo THA or TKA were enrolled and surveyed. A control group (CG) was also surveyed for comparison with the patients. The patients were preoperatively examined for truncal parameters using the Diers Formetric four-D analysis system (surface topography technique) to calculate several truncal parameters in all planes at four months and 12 months postoperatively. Measurable examinations were performed using the Statistical Package for the Social Sciences (SPSS) version 17.00 (SPSS Inc., Chicago), and statistical significance was set at a p-value of <0.05.ResultsThe study examined 34 patients who underwent THA, including 19 women and 15 men with a mean age of 67.62 ± 8.28 years. The study also examined 45 patients who underwent TKA, including 34 women and 11 men, with a mean age of 72.42 ± 7.0 years. These patients were also compared with a CG that consisted of 25 normal individuals, including 12 women and 13 men, with a mean age of 69.28 ± 10.11 years.The results of this study from four months after THA revealed that the lordotic angle, trunk torsion, pelvic inclination, pelvic obliquity, and pelvis rotation were improved to normal levels. At 12 months after THA, only the pelvic obliquity was improved to normal levels. At four months after TKA the lordotic angle, pelvic inclination, and pelvic obliquity were improved to normal levels. However, the fleche cervicale and vertebral rotation were worse. At 12 months after TKA, only the pelvic obliquity was improved to normal levels.ConclusionsTHA and TKA to correct hip and knee OA do not correct the disordered morphology of the trunk in the long term. Thus, hip or knee OA does not seem to be responsible for disordered trunk morphology. However, it cannot be ruled out whether the disturbed morphology is responsible for the appearance of the hip and knee OA.

Large Torsional Rotation and Rotational Inversion Coupling with Linear Deformation of Electromechanical Actuators Based on Conductive Micro-/Nano-Helices

Large Torsional Rotation and Rotational Inversion Coupling with Linear Deformation of Electromechanical Actuators Based on Conductive Micro-/Nano-Helices

Finite Element Analysis on Triangular Web Profile Steel Section with Opening: Effects of Torsion Behaviour

In recent decades, there is a massive demand for steel sections that normally used in the construction of roads, railways, other infrastructures, appliances and buildings.This paper summarizes the torsion behaviour analysis for triangular web profile steel section with opening. Comparison on parametrical study is made using LUSAS software between triangular web profiles steel sections without opening and triangular web profile steel section with opening. A total of eighty finite elements analyses involve the changes of web thickness, flange thickness, span length, incremental loading, and size of circular opening were run to investigate the torsion behaviour effect on web opening shapes. The value of displacement and torsional rotation are the outcome of the final results. It was observed that triangular web profile steel section without web opening are able to maintain the static equilibrium by having higher torsional resistance compared to that of section with web opening.