Torsional Pattern Research Articles

Synergistically flexible-robust effects mediate the dynamic reconfiguration of perylene diimide polymer to enhance piezo-photocatalytic nitrate reduction

Identifying the spatial dynamic reconstruction of π-conjugated polymers for efficient carrier transport and controlling the intermediate process of the reaction are urgent and formidable challenges. In this study, a fresh perspective has emerged proposing to synergistically enhance the adaptability and resilience of dynamic torsion patterns in π-conjugated polymers to mediate charge separation and molecular activation. Excitingly, the highest flexible-robust structure and polarity of naphthalene-linked perylene diimide polymer (N-PDA) demonstrates a highest nitrate reduction rate of 5.36 mmol g−1 h−1 under light irradiation and ultrasonic condition, which is 7.5 times that of H-PDA. Theoretical calculations and experimental observations indicate that the strongest flexible-robust structure of N-PDA enhances the inclination of the rigid plane and atomic bond length, resulting in an accelerated uneven distribution of charges, molecular polarity, and electronic coupling to facilitate charge separation dynamics. Moreover, it exposes active sites that promote the adsorption and activation of NO3- ions while simultaneously regulating intermediate hydrogenation processes. Our study offers innovative prospects for enhancing catalytic efficiency through the implementation of spatial steric configuration of π-conjugated polymers.

Single Ventricular Torsional Mechanics After Fontan Palliation and Their Impact on Outcomes

BackgroundAbnormal left ventricular (LV) rotational mechanics in biventricular hearts are associated with adverse outcomes; however, these are less well characterized for hearts with functionally single ventricles. ObjectivesThe purpose of this study was to characterize ventricular rotational mechanics in the Fontan circulation and their relationship to outcomes. MethodsSingle-center, retrospective analysis of magnetic resonance examinations for 329 Fontan patients (15 [IQR: 10-21] years) and 42 controls. The ventricular cine short-axis stack was analyzed to derive torsion metrics. Torsion calculated as the difference between apical and basal rotation normalized to ventricular length. ResultsFontan patients had higher indexed ventricular end-diastolic volume (97 mL/body surface area1.3 vs 72 mL/body surface area1.3), lower ejection fraction (53% vs 60%), and lower proportion of basal clockwise rotation (62% vs 93%), apical counterclockwise rotation (77% vs 95%), and positive torsion (82% vs 100%); P < 0.001 for all. A composite outcome of death or heart transplant-listing occurred in 31 (9%) patients at a median follow-up of 3.9 years. Torsion metrics were associated with the outcome; although, on multivariate analysis only right ventricular (RV) morphology and indexed ventricular end-diastolic volume were independently associated. LVs with negative torsion, and RVs regardless of torsional pattern, had worse outcomes compared to LVs with positive torsion (P = 0.020). ConclusionsSingle ventricles in a Fontan circulation exhibit abnormal torsional mechanics, which are more pronounced for RV morphology. Abnormal torsion is associated with death or need for heart transplantation. Fontan patients with LV morphology and preserved torsion exhibit the highest transplant-free survival and torsion may offer incremental prognostic data in this group of patients.

Metallographic characterization of a gold-steel composite

Abstract A gold-steel composite material for decorative applications was manufactured by forging. This procedure can be referred to as modified damascene technique. Sheets made of steel K110 (C-rich cold work steel) and gold sheets were assembled and forged together at approx. 800 °C. The bar was subsequently twisted to obtain the typical torsion pattern. The end portions of this bar were subjected to a metallographic examination. The steel K110 shows broken carbides which were formed during the forging process. The carbides can be etched using Murakami’s reagent, whereas a 3 % Nital solution can be used to etch the steel matrix. Gold etching was challenging because many etchants suitable to etch gold preferentially attack the steel. In reference to gold extraction by cyanide leaching, a KCN solution was used as etchant. It could be shown that atmospheric oxygen acting as an oxidant is already sufficient to etch gold. However, using a KCN-H2O2 mixture provides a more efficient etching effect. Gold grains in the gold layers can reach a size of up to 1 mm. A diffusion zone with a thickness of approx. 10 μm can be observed at the steelgold interfaces.

The register shift rules for βαβ-motifs for de novo protein design.

A wide range of de novo design of αβ-proteins has been achieved based on the design rules, which describe secondary structure lengths and loop torsion patterns favorable for design target topologies. This paper proposes design rules for register shifts in βαβ-motifs, which have not been reported previously, but are necessary for determining a target structure of de novo design of αβ-proteins. By analyzing naturally occurring protein structures in a database, we found preferences for register shifts in βαβ-motifs, and derived the following empirical rules: (1) register shifts must not be negative regardless of torsion types for a constituent loop in βαβ-motifs; (2) preferred register shifts strongly depend on the loop torsion types. To explain these empirical rules by physical interactions, we conducted physics-based simulations for systems mimicking a βαβ-motif that contains the most frequently observed loop type in the database. We performed an exhaustive conformational sampling of the loop region, imposing the exclusion volume and hydrogen bond satisfaction condition. The distributions of register shifts obtained from the simulations agreed well with those of the database analysis, indicating that the empirical rules are a consequence of physical interactions, rather than an evolutionary sampling bias. Our proposed design rules will serve as a guide to making appropriate target structures for the de novo design of αβ-proteins.

Testicular torsion: An assessment of knowledge and referral pattern among health care workers in primary health-care facilities in Auchi, Nigeria

Objectives: Testicular torsion is the twisting of the spermatic cord with attendant loss of the blood supply to the affected testis. It is a common urological emergency and one of the frequent causes of acute scrotum in adolescents and young adults. Prompt diagnosis and immediate surgical intervention are necessary for testicular salvage. Testicular loss is directly linked to delay in presentation, surgery, and the referral patterns at the point of the first contact with health-care providers. The purpose of our study is to assess the knowledge, management methods, and referral pattern among health care workers in the primary health-care facilities in Auchi primary health-care zone, Nigeria. Material and Methods: This was a cross-sectional carried out among primary health care workers in Auchi primary health-care zone between May and October 2020. A structured self-administered questionnaire was given to all the first contact health care workers in this zone. The knowledge, management, and referral pattern of testicular torsion were determined based on responses to the questionnaires. Data were analyzed using SPSS version 21. Results were displayed with frequency distribution tables and charts. Results: Eighty-seven health care workers met the inclusion criteria and were given questionnaires to fill. The mean age of the respondents was 37.74 ± 7.53 years. The majority of the health workers (n = 66, 75.9%) have more than 5 years’ experience with only 12 (13.8%) having a secondary level of education. Most respondents have heard of testicular torsion (n = 77, 88.5%) and know the symptoms (n = 68, 78.2%) but they have a poor knowledge of the age group predominantly affected (n = 36, 41.1%) and testicular survival time following torsion (n= 41, 47.7%). Only about a third (n = 28, 32.2%) had attended to patients with testicular torsion. Of the 28 health workers who had managed patients with testicular torsion, less than half (n = 11, 39.3%) referred almost immediately, while about half treated conservatively (n = 14, 49.9%) keeping the patients under their care for a period of 3–7 days. Conclusion: This study showed that a comprehensive education of all categories of health workers in the primary health-care centers is needed. This is necessary for the early identification and appropriate surgical intervention or prompt referral of patients with testicular torsion to prevent avoidable testicular losses.

Rotation and torsion of the left ventricle with cardiovascular magnetic resonance tagging: comparison of two analysis methods

BackgroundLeft ventricle rotation and torsion are fundamental components of myocardial function, and several software packages have been developed for analysis of these components. The purpose of this study was to compare the suitability of two software packages with different technical principles for analysis of rotation and torsion of the left ventricle during systole.MethodsA group of hypertrophic cardiomyopathy (HCM) patients (N = 14, age 43 ± 11 years), mutation carriers without hypertrophy (N = 10, age 34 ± 13 years), and healthy relatives (N = 12, age 43 ± 17 years) underwent a cardiovascular magnetic resonance examination, including spatial modulation of magnetization tagging sequences in basal and apical planes of the left ventricle. The tagging images were analyzed offline using a harmonic phase image analysis method with Gabor filtering and a non-rigid registration-based free-form deformation technique. Left-ventricle rotation and torsion scores were obtained from end-diastole to end-systole with both software.ResultsAnalysis was successful in all cases with both software applications. End-systolic torsion values between the study groups were not statistically different with either software. End-systolic apical rotation, end-systolic basal rotation, and end-systolic torsion were consistently higher when analyzed with non-rigid registration than with harmonic phase-based analysis (p < 0.0001). End-systolic rotation and torsion values had significant correlations between the two software (p < 0.0001), most significant in the apical plane.ConclusionsWhen comparing absolute values of rotation and torsion between different individuals, software-specific reference values are required. Harmonic phase flow with Gabor filtering and non-rigid registration-based methods can both be used reliably in the analysis of systolic rotation and torsion patterns of the left ventricle.

Synchrotron spectroscopy of the CSH-bending and CH3-rocking bands of methyl mercaptan

The CSH-bending and CH3-rocking infrared bands of CH3SH have been investigated in Fourier transform spectra recorded at 0.001 cm−1 resolution employing synchrotron radiation at the Canadian Light Source in Saskatoon. The relative band strengths and structures are quite different from those of the CH3OH methanol analogue, with the CSH bend being very weak and both the in-plane and out-of-plane CH3 rocks being strong with intensities greater than the C–S stretch. The CSH bend has parallel a-type character with no detectable b-type component. The out-of-plane CH3 rock is a purely c-type perpendicular band, whereas the in-plane rock is of mixed a/b character. Sub-bands have been assigned for A and E torsional species up to about K = 10 for each vibrational mode, providing upper-state term values from which K-reduced substate origins were determined. For the CSH bend, the origins follow the customary oscillatory torsional pattern as a function of K with a sharply reduced amplitude of 0.362 cm−1 compared to the 0.653 cm−1 for the ground state. The torsional energy curves for the out-of-plane rock are also well-behaved but have inverted ordering of the A–E torsional splitting components and a larger amplitude of 1.33 cm−1. In contrast, the substate origins for the in-plane rock are scattered over a range of about 2 cm−1 without clear oscillatory structure. Several instances of coupling among the lower modes and the ground state via resonances between accidentally near-degenerate levels have been observed and characterized. Ab initio calculations are found to give a good representation of the frequency and relative intensity patterns for the lower vibrational modes.

A semiclassical approach to the torsional tunneling splitting patterns in G6(EM), G12, G18, and G36(EM) molecules

A semiclassical method to predict the torsional splitting patterns in internally rotating molecules of G6(EM), G12, G18, and G36(EM) symmetries is described. To this purpose use is made of rotating axis systems denoted “Corioless”, in which the contribution to the torsional angular momentum from specific vibrational motions of the molecule, or part of it, vanishes. It is confirmed that the actual torsional splitting patterns in degenerate or perpendicular vibrational states can be predicted analytically and are determined by torsional Coriolis coupling. Rules stating the conditions required to generate limit splitting patterns (regular and inverted) are formulated in a quite general way and derived for the first time in the case of G18 molecules.

In-situ optical assessment of rat epicardial kinematic parameters reveals frequency-dependent mechanic heterogeneity related to gender

BackgroundGender-related cardiac mechanics following the electrical activity has been investigated from basic to clinical research, but results are still controversial. The aim of this work is to study the gender related cardiac mechanics and to focus on its heart rate dependency. MethodsWe employed 12 Sprague Dawley rats (5 males and 7 females) of the same age and, through a novel high resolution artificial vision contactless approach, we evaluated in-situ cardiac kinematic. The hearts were paced on the right atria appendage via cathodal stimuli at rising frequency. ResultsKinematic data obtained at rising pacing rates are different between male and female rat hearts: male tended to maintain the same level of cardiac force, energy and contractility, while female responded with an increment of such parameters at increasing heart rate. Female hearts preserved their pattern of contraction and epicardial torsion (vorticity) at rising pacing rates compared to male. Furthermore, we observed a difference in the mechanical restitution: systolic time vs. diastolic time, as an index of cardiac performance, reached higher value in male compared to female hearts. ConclusionOur innovative technology was capable to evaluate in-situ rat epicardial kinematic at high stimulation frequency, revealing that male preserved kinematic parameters but varying the pattern of contraction/relaxation. On the contrary, female preserved the pattern of contraction/relaxation increasing kinematic parameters.

Regional cardiac function analysis from tagged MRI images. Comparison of techniques: Harmonic-Phase (HARP) versus Sinusoidal-Modeling (SinMod) analysis

Cardiac MRI tagging is a valuable technique for evaluating regional heart function. Currently, there are a number of different techniques for analyzing the tagged images. Specifically, k-space-based analysis techniques showed to be much faster than image-based techniques, where harmonic-phase (HARP) and sine-wave modeling (SinMod) stand as two famous techniques of the former group, which are frequently used in clinical studies. In this study, we compared HARP and SinMod and studied inter-observer variability between the two techniques for evaluating myocardial strain and apical-to-base torsion in numerical phantom, nine healthy controls, and thirty diabetic patients. Based on the ground-truth numerical phantom measurements (strain = −20% and rotation angle = −4.4°), HARP and SinMod resulted in overestimation (in absolute value terms) of strain by 1% and 5% (strain values), and of rotation angle by 0.4° and 2.0°, respectively. For the in-vivo results, global strain and torsion ranges were −10.6% to −35.3% and 1.8°/cm to 12.7°/cm in patients, and −17.8% to −32.7% and 1.8°/cm to 12.3°/cm in volunteers. On average, SinMod overestimated strain measurements by 5.7% and 5.9% (strain values) in the patients and volunteers, respectively, compared to HARP, and overestimated torsion measurements by 2.9°/cm and 2.5°/cm in the patients and volunteers, respectively, compared to HARP. Location-wise, the ranges for basal, mid-ventricular, and apical strain in patients (volunteers) were −8.4% to −31.5% (−11.6% to −33.3%), −6.3% to −37.2% (−17.8% to −33.3%), and −5.2% to −38.4% (−20.0% to −33.2%), respectively. SinMod overestimated strain in the basal, mid-ventricular, and apical slices by 4.7% (5.7%), 5.9% (5.5%), and 8.9% (6.8%), respectively, compared to HARP in the patients (volunteers). Nevertheless, there existed good correlation between the HARP and SinMod measurements. Finally, there were no significant strain or torsion measurement differences between patients and volunteers. There existed good inter-observer agreement, as all measurement differences lied within the Bland-Altman ± 2 standard-deviation (SD) difference limits. In conclusion, despite the consistency of the results by either HARP or SinMod and acceptable agreement of the generated strain and torsion patterns by both techniques, SinMod systematically overestimated the measurements compared to HARP. Under current operating conditions, the measurements from HARP and SinMod cannot be used interchangeably.

P4357Left ventricular torsion and rigid body rotation pattern in patients treated with anthracycline

P4357Left ventricular torsion and rigid body rotation pattern in patients treated with anthracycline

Age- and sex-associated morphological variations of metatarsal torsional patterns in humans.

It has been demonstrated that the torsional patterns of the metatarsal heads are associated with the presence or absence of the medial longitudinal arch in hominoid feet. The relatively untwisted second metatarsal is unique in humans, but that of the African apes is much more inverted, suggesting that the torsion of the second metatarsal might represent the overall shape and flatness of the foot. Some clinical studies have recently argued that the onset of foot pathologies such as hallux valgus might be related to the torsional pattern of the metatarsals. However, to date, no studies have systematically investigated the morphological variations of the torsional patterns of human metatarsals. In this study, therefore, the aim was to clarify the age- and sex-associated variations in the torsional patterns of human metatarsals using three-dimensional computed tomography. The torsion angles of the five metatarsals were calculated by defining the dorsopalmar vector of the metatarsal base and the vector corresponding to the rotational axis of the metatarsal head. The present result demonstrated that the second metatarsals of females were significantly more inverted with increasing age. Flat foot is known to be most common in elderly women. Whether there is a cause-effect relationship between second metatarsal torsion and flattening of the medial longitudinal arch has yet to be answered, but this study suggested that torsion of the second metatarsal might possibly be used as an indicator for the early diagnosis of flat foot and associated foot pathologies. Clin. Anat. 30:1058-1063, 2017. © 2017 Wiley Periodicals, Inc.

105 Differences in myocardial mechanics between ischaemic and non-ischaemic cardiomyopathy assessed by cmr: a sub-group analysis of the vindicate trial

BackgroundPrognosis and treatment of patients with chronic heart failure (CHF) differs according to whether it is ischaemic (ICM) or non-ischaemic cardiomyopathy (NICM). Multi-parametric cardiovascular magnetic resonance (CMR) can distinguish these...

Impact of torsion and stretching on the thermal conductivity of polyethylene strands

A single polyethylene chain was reported to have a high metal-like thermal conductivity (TC), which stands in sharp contrast to the thermally insulating feature of common bulk polyethylene materials. This work numerically investigates the impact of torsion and stretching on the TC of polyethylene strands by using equilibrium molecular dynamics simulations. The simulation results show that torsion slightly reduces the TC of a single polyethylene chain. In contrast, the heat conduction of polyethylene strands could be slightly enhanced under torsional loading with a specific torsional angle. Particularly, an apparent improvement of TC of polyethylene strands is achieved by combining torsion and stretching functions. It is found that the TC of torsional polyethylene strands is sensitive to torsional patterns. Our study proposes a specific torsional pattern of polyethylene strands that significantly enhances the heat conduction of the original counterpart. This study will play an essential role in guiding the improvements of thermal conduction property of polymers.

Advanced hallux limitus and its relationship with the internal rotational pattern and the foot progression angle

IntroductionThe aim of this study was to determine whether subjects with advanced hallux limitus show a diminished ability of internal rotation of the lower limb and increased foot progression angle compared with normal population. It was also intended to relate rotational and torsional patterns of lower limbs with the foot progression angle, and to compare three different methods of measurement of the foot progression angle. Patients and methodsInternal and external rotational pattern, internal and external hip rotation and tibial torsion were measured in 30 feet of 15 subjects with advanced hallux limitus and 103 normal feet. The foot progression angle was also obtained using a pressure platform and an inked latex carpet. ResultsThe internal rotation of the lower limb was significantly lesser and the foot progression angle was significantly greater in individuals with advanced hallux limitus (p<0.05). The Pearson correlation coefficient was −0.563 (p<0.01) for the relationship between the foot progression angle and the internal rotational pattern. The measure of the foot progression angle in the inked latex carpet was significantly greater than in the pressure platform in the left foot (p<0.05). ConclusionSubjects with advanced hallux limitus had a lesser capacity of internal rotation of the lower extremity and greater foot progression angle in comparison with normal population. Internal rotational pattern determines the greater foot progression angle. The foot progression angle values measured with the pressure platform differ from those of the inked latex carpet.

Relación del hallux limitus avanzado con el patrón rotador interno y el ángulo de la marcha

IntroductionThe aims of this study were to determine whether subjects with advanced hallux limitus show a diminished capacity of internal rotation of the lower limb and increased foot progression angle compared with normal population, to relate rotational and torsional patterns of lower limbs with the foot progression angle, and to compare methods of measurement of the foot progression angle. Patients and methodsIn 15 subjects with advanced hallux limitus, internal and external rotational pattern, internal and external hip rotation and tibial torsion were measured. The foot progression angle was obtained using a pressure platform and an inked latex carpet. ResultsThe internal rotation of the lower limb was significantly lesser and the foot progression angle was significantly greater in individuals with advanced hallux limitus (P<.05). The Pearson correlation coefficient was −0,563 (P<.01) for the relationship between the foot progression angle and the internal rotational pattern. The measure of the foot progression angle in the inked latex carpet was significantly greater than in the pressure platform in the left foot (P<.05). ConclusionSubjects with advanced hallux limitus had a lesser capacity of internal rotation of the lower extremity and greater foot progression angle in comparison with normal population. Internal rotational pattern determines the greater foot progression angle. The foot progression angle values measured with the pressure platform differ from the inked latex carpet.

Torsion Library Reloaded: A New Version of Expert-Derived SMARTS Rules for Assessing Conformations of Small Molecules.

The Torsion Library contains hundreds of rules for small molecule conformations which have been derived from the Cambridge Structural Database (CSD) and are curated by molecular design experts. The torsion rules are encoded as SMARTS patterns and categorize rotatable bonds via a traffic light coloring scheme. We have systematically revised all torsion rules to better identify highly strained conformations and minimize the number of false alerts for CSD small molecule X-ray structures. For this new release, we added or substantially modified 78 torsion patterns and reviewed all angles and tolerance intervals. The overall number of red alerts for a filtered CSD data set with 130 000 structures was reduced by a factor of 4 compared to the predecessor. This is of clear advantage in 3D virtual screening where hits should only be removed by a conformational filter if they are in energetically inaccessible conformations.

Tailoring patterns of graphene wrinkles by circular torsion

Wrinkled graphene has been emerging as a hot topic of interest due to its easily induced physical changes accompanied by changes in its material behavior. However, the wrinkling pattern of graphene and its relevant properties remain poorly understood. Here we employ molecular dynamics simulations to model the behavior of graphene under periodic, torsional wrinkling and elucidate the effect of torsion pattern, torsion velocity, and hole size on the wrinkling characteristics of a large graphene sheet. Simulation results show that gross control over the wrinkling pattern is feasible via manipulation of torsion direction and relative hole size, with fine-tuning of the wrinkle formation possible by control of the relative torsion speed of each hole.

The cardiac torsion as a sensitive index of heart pathology: A model study

The torsional behaviour of the heart (i.e. the mutual rotation of the cardiac base and apex) was proved to be sensitive to alterations of some cardiovascular parameters, i.e. preload, afterload and contractility. Moreover, pathologies which affect the fibers architecture and cardiac geometry were proved to alter the cardiac torsion pattern. For these reasons, cardiac torsion represents a sensitive index of ventricular performance. The aim of this work is to provide further insight into physiological and pathological alterations of the cardiac torsion by means of computational analyses, combining a structural model of the two ventricles with simple lumped parameter models of both the systemic and the pulmonary circulations. Starting from diagnostic images, a 3D anatomy based geometry of the two ventricles was reconstructed. The myocytes orientation in the ventricles was assigned according to literature data and the myocardium was modelled as an anisotropic hyperelastic material. Both the active and the passive phases of the cardiac cycle were modelled, and different clinical conditions were simulated. The results in terms of alterations of the cardiac torsion in the presence of pathologies are in agreement with experimental literature data. The use of a computational approach allowed the investigation of the stresses and strains in the ventricular wall as well as of the global hemodynamic parameters in the presence of the considered pathologies. Furthermore, the model outcomes highlight how for specific pathological conditions, an altered torsional pattern of the ventricles can be present, encouraging the use of the ventricular torsion in the clinical practice.

Damage characterization on human femur bone by means of ultrasonics and acoustic emission

Human bone tissue is characterized as a material with high brittleness. Due to this nature, visible signs of cracking are not easy to be detected before final failure. The main objective of this work is to investigate if the acoustic emission (AE) technique can offer valuable insight to the fracture process of human femur specimens as in other engineering materials characterization. This study describes the AE activity during fracture of whole femur bones under flexural load. Before fracture, broadband AE sensors were used in order to measure parameters like wave velocity dispersion and attenuation. Waveform parameters like the duration, rise time and average frequency, were also examined relatively to the propagation distance as a preparation for the AE monitoring during fracture. After the ultrasonic study, the samples were partly cast in concrete and fixed as cantilevers. A point load was applied on the femur head, which due to the test geometry resulted in a combination of two different patterns of fracture, bending and torsion. Two AE broadband sensors were placed in different points of the sample, one near the fixing end and the other near the femur head. Preliminary analysis shows that parameters like the number of acquired AE signals and their amplitude are well correlated with the load history. Furthermore, the parameters of rise time and frequency can differentiate the two fracture patterns. Additionally, AE allows the detection of the load at the onset of fracture from the micro-cracking events that occur at the early loading stages, allowing monitoring of the whole fracture process. Parameters that have been used extensively for monitoring and characterization of fracture modes of engineering materials seem to poses characterization power in the case of bone tissue monitoring as well.