Stability Of Ring Research Articles

Mechanical disengagement of the cohesin ring

Cohesin forms a proteinaceous ring that is thought to link sister chromatids by entrapping DNA and counteracting the forces generated by the mitotic spindle. Whether individual cohesins encircle both sister DNAs and how cohesin opposes spindle-generated forces remains unknown. Here we perform force measurements on individual yeast cohesin complexes either bound to DNA or holding together two DNAs. By covalently closing the hinge and Smc3Psm3–kleisin interfaces we find that the mechanical stability of the cohesin ring entrapping DNA is determined by the hinge domain. Forces of ~20 pN disengage cohesin at the hinge and release DNA, indicating that ~40 cohesin molecules are sufficient to counteract known spindle forces. Our findings provide a mechanical framework for understanding how cohesin interacts with sister chromatids and opposes the spindle-generated tension during mitosis, with implications for other force-generating chromosomal processes including transcription and DNA replication.

Aeroelastic stability of labyrinth seal ring under steady and dynamic total pressure intake distortion conditions

Aiming at the aeroelastic stability of labyrinth seal ring under intake distortion condition, a numerical model for the aeroelastic stability of labyrinth seal ring with intake distortion was established, which was based on the energy method and used 3D interpolation and unsteady dynamic mesh technology. Based on the experimental verification of the method, the effects of the steady and dynamic total pressure intake distortion and the dynamic total pressure uniform intake on the aeroelastic stability of the labyrinth seal ring were studied, including the location and level. Moreover, the characteristics of labyrinth seal aerodynamic work distribution were analyzed. The results show that the position of the steady total pressure intake distortion has no effect on the aeroelastic stability, but the level of distortion has a significant effect, which increase the probability of the aeroelastic instability in 2 and 3 nodal diameters. Under the same intake area condition, asymmetric intake is more prone to aeroelastic instability than symmetric intake. For the dynamic total pressure uniform intake, the type of the time and signal of increasing/decreasing pressure has little influence on aeroelastic stability. The labyrinth seal ring under steady total pressure intake distortion is more likely to cause aeroelastic instability than dynamic state. In addition, the aerodynamic work distribution characteristics of dynamic and symmetrical steady total pressure intake distortion are basically consistent with the uniform intake, and the aerodynamic work is distributed periodically along the axial direction with an approximate law. When the aeroelastic instability occurs due to the asymmetric steady total pressure intake distortion, the percentage of aerodynamic work of tooth unit components in total aerodynamic work changes significantly, and 95.7% of the total aerodynamic work is contributed by tooth unit TU#1. The above researches provide a theoretical basis for aeroelastic stability of labyrinth seal ring.

О влиянии односторонних связей на устойчивость и колебания упругих колец

The paper deals with the issues of stability of a circular ring
 compressed by uniformly distributed central forces in the
 presence of one-sided restrictions on displacements. In the
 second part of the article, the problem of oscillations of a ring
 supported by single-acting threads is solved. The problems
 are reduced to solving some variational problem under restrictions
 on the desired functions in the form of linear equations
 and inequalities

The dusty Rossby wave instability (DRWI): linear analysis and simulations of turbulent dust-trapping rings in protoplanetary discs

ABSTRACT Recent numerical simulations have revealed that dust clumping and planetesimal formation likely proceed in ring-like disc substructures, where dust gets trapped in weakly turbulent pressure maxima. The streaming instability has difficulty operating in such rings with external turbulence and no pressure gradient. To explore potential paths to planetesimal formation in this context, we analyse the stability of turbulent dust-trapping ring under the shearing sheet framework. We self-consistently establish the pressure maximum and the dust ring in equilibrium, the former via a balance of external forcing versus viscosity and the latter via dust drift versus turbulent diffusion. We find two types of ≳ H-scale instabilities (H being the pressure scale height), which we term the dusty Rossby wave instability (DRWI). Type I is generalized from the standard Rossby wave instability (RWI, which is stationary at the pressure maximum and dominates in relatively sharp pressure bumps. Type II is a newly identified travelling mode that requires the presence of dust. It can operate in relatively mild bumps, including many that are stable to the standard RWI, and its growth rate is largely determined by the equilibrium gas and dust density gradients. We further conduct two-fluid simulations that verify the two types of the DRWI. While Type I leads strong to dust concentration into a large gas vortex similar to the standard RWI, the dust ring is preserved in Type II, and meanwhile exhibiting additional clumping within the ring. The DRWI suggests a promising path towards formation of planetesimals/planetary embryos and azimuthally asymmetric dust structure from turbulent dust-trapping rings.

A machine-learning based closed orbit feedback for a synchrotron light source

In order to improve the stability of synchrotron radiation, we developed a new method of machine learning-based closed orbit feedback, and piloted it in the storage ring of the Shanghai Synchrotron Radiation Facility (SSRF). In our experiments, the machine learning-based closed orbit feedback can carry out horizontal, vertical and RF main frequency feedback simultaneously. What's more, the residual values of variations in the correctors' currents before vs. after correction can be almost ignored. This machine learning-based new method is expected to establish a new closed orbit feedback system and improve the orbit stability of the storage ring in daily operation.

An Experimental Study on the Influence of the Fractal Characteristics of X80 Steel Surface Morphology on Water Ring Stability

The surface morphology of X80 steel with hydrophilic underwater oleophobic characteristic is described greater comprehensively and quantitatively in this work by combining fractal dimension and multifractal. X80 steel with hydrophilic underwater oleophobic surface characteristics was constructed using a chemical etching method. Then, with the aid of three wettability parameters—contact angle, rolling angle, and adhesion work—this study investigated the relationship between the surface fractal dimension of X80 and the stability of the water ring in the core annular flow. The results showed that: (1) the fractal dimension of X80 steel specimens increased first and then decreased with the increase of reaction time. Besides that, the value of it was greater than 2, indicating that the surface had obvious fractal characteristics. The spectral difference, Δf(α), and the spectral width, Δα, supplemented the description of the X80 steel surface morphology, which was consistent with the scanning electron microscope results. (2) When the maximum fractal dimension was 2.0808, the minimum contact angle of distilled water on its surface was 50.2°, and the maximum contact angle of underwater oil droplets was 166.4°. The larger the fractal dimension of X80 steel with hydrophilic underwater oleophobic properties, the more hydrophilic and underwater oleophobic it is. This illustrated that there was a strong binding force between the water and the X80 steel pipe wall, and hence the quality and efficiency of the core annular flow was improved, which was more conducive to the promotion of this technology in the field of heavy oil transportation.

Machine learning accelerated design of 2D covalent organic frame materials for thermoelectrics

Both thermodynamic stability and high thermoelectric figure of merit are required for organic thermoelectric materials for practical application. However, it is extremely time-consuming to design advanced organic thermoelectric materials via conventional theoretical calculation. In this work, combining first-principles calculations, machine learning fitted potential and solving phonon Boltzmann transport equation, we propose a new group of two-dimensional covalent organic frame semiconductors 2AL-PR-X (X = 2H, Ni, Pt, Zn) as promising organic thermoelectric materials. We found that the embedding metal atoms in the center can enhance remarkably the stability of porphyrin ring, demonstrated by evaluating the system total energy and phonon dispersion relationship. Moreover, the interaction between the metal atoms and the porphyrin ring will affect the phonon modes in the porphyrin ring, result in reduction in thermal conductivity. We found that 2AL-PR-Pt is the best thermoelectric candidate material among the studied 2AL-PR-X, which has a peak ZT of 0.32 at room temperature and can reach around 0.9 at 800 K. Our work provides strategy for the thermal transport regulation of two-dimensional covalent organic frame materials and demonstrates the large potential of 2AL-PR-X materials for thermoelectric applications.

Effect of N-aryl para-benzhydryl substituent on the thermal stability of α-diimine nickel catalyst.

The thermal stability of α-diimine nickel catalysts has always been the focus of research. The introduction of large groups in the backbone or N-aryl ortho-position is a relatively mature solution. However, the question of whether the N-aryl bond rotation is a factor affecting the thermal stability of nickel catalysts is still open. In this work, the effects of N-aryl para-benzhydryl substitutes on catalyst thermal stability were investigated, and the results of ethylene polymerization and the factors affecting thermal stability (steric effect, electronic effect, five-membered coordination ring stability, N-aryl bond rotation, etc.) were systematically analysed. It is believed that the introduction of large steric hindrance groups at the N-aryl para-position hinders the rotation of the N-aryl bond. This obstacle effect is beneficial to improving catalyst thermal stability, and the obstacle capacity is weakened with the increase of ortho-substituent size. This article is protected by copyright. All rights reserved.

On the elastic stability of folded rings in circular and straight states

Single-loop elastic rings can be folded into multi-loop equilibrium configurations. In this paper, the stability of several such multi-loop states which are either circular or straight are investigated analytically and illustrated by experimental demonstrations. The analysis ascertains stability by exploring variations of the elastic energy of the rings for admissible deformations in the vicinity of the equilibrium state. The approach employed is the conventional stability analysis for elastic conservative systems based on the second variation of the system energy which differs from most of the analyses that have been published on this class of problems, as will be illustrated by reproducing and elaborating on several problems in the literature. In addition to providing solutions to two basic problems, the paper analyses and demonstrates the stability of six-sided rings, curved-sided hexagrams, that fold into straight configurations.

The EMS stress view: occult pelvic instability revealed by pre-hospital pelvic binder placement.

To describe and evaluate the serendipitous pelvic binder stress radiographs of lateral compression type (LC) pelvic ring injuries. This was a retrospective case series performed at a single, level I academic trauma center from 2016 to 2018. All patients presenting with a minimally displaced LC pelvic ring injury were reviewed (< 10cm displacement on static pelvic radiographs). Patients with X-rays (XR) in a pelvic binder (EMS stress) and with the pelvic binder removed were included. Pelvic ring stability was determined by attending surgeon evaluation of EMS stress radiographs versus static XR of the pelvis. Patients were treated non-operatively and allowed to weight bear or taken to the operating room for exam under anesthesia (EUA) and potential operative fixation. Clinical success of treatment was determined by evaluation of further displacement at the completion of their most recent follow-up. Thirty-seven patients of the initial 398 reviewed met inclusion criteria. Fourteen of 37 patients (38%) were categorized as stable with no significant pelvis displacement seen on EMS stress and were treated non-operatively without further sequelae (4.6 months mean follow-up). The remaining 23/37 (62%) were treated operatively. Occult instability was identified on EMS stress in 14 (61%) of those 23 patients and the remainder were determined to be unstable based upon fracture pattern or EUA. All patients went on to successful treatment without significant pelvic deformity (7.8 months mean follow-up). The EMS stress XR is a valuable, opportunistic evaluation in LC pelvic ring injuries. This evaluation is a useful diagnostic adjunct to alert the provider that additional stress imaging may be indicated to evaluate for occult pelvic ring instability.

Pelvic ring injuries: recent advances in diagnosis and treatment.

Pelvic ring injuries typically occur from high-energy trauma and are often associated with multisystem injuries. Prompt diagnosis of pelvic ring injuries is essential, and timely initial management is critical in the early resuscitation of polytraumatized patients. Definitive management of pelvic ring injuries continues to be a topic of much debate in the trauma community. Recent studies continue to inform our understanding of static and dynamic pelvic ring stability. Furthermore, literature investigating radiographic and clinical outcomes after nonoperative and operative management will help guide trauma surgeons select the most appropriate treatment of patients with these injuries.

AN ANALYSIS OF INDIA'S AGRICULTURAL SECTOR: CHALLENGES AND OPPORTUNITIES

Introduction: Open fractures of the pelvis represent one of the most fatal injuries within musculoskeletal trauma so they must be treated correctly, adjusting to a multidisciplinary approach to achieve the well-being of the affected person, in addition to restoring homeostasis and normal pathophysiology related to the mechanical stability of the pelvic ring. Objective: to detail current information related to pelvic fractures, epidemiology, anatomy, mechanism of injury, classification, imaging presentation, clinical presentation, management and complications. Methodology: a total of 27 articles were analyzed in this review, including review and original articles, as well as clinical cases, of which 20 bibliographies were used because the other articles were not relevant for this study. The sources of information were PubMed, Google Scholar and Cochrane; the terms used to search for information in Spanish, Portuguese and English were: fracturas de pelvis, fraturas do anel pelvico, anatomy of the pelvis, fractures of the pelvis. Results: Most cases of pelvic fractures occur in young people due to high-energy mechanisms, although injuries can also be generated by low-energy mechanisms and can cause fractures of individual bones. Mortality is higher in individuals with hemodynamic instability. The standard imaging examinations in trauma are anteroposterior projections of the thorax, lateral cervical spine and anteroposterior projections of the pelvis; special projections of the pelvis include the oblique alar and obturator projections. The severity of pelvic fractures is closely related to the associated injuries. Conclusions: Knowledge of anatomy is a fundamental piece in the treatment of pelvic fractures and associated injuries. There are several systems for classifying pelvic fractures, according to anatomical patterns, mechanisms of injury, resulting instability requiring surgery. The most frequently used is that of Young and Burgess. For evaluation, one should start with the ABCDE, airway, breathing, circulation, disability, and exposure and integrate a complete traumatologic evaluation. To determine whether there is pelvic instability, the anteroposterior and lateral compression test is performed for one occasion, generating internal and external rotation of the pelvis. The spine and extremities should be well assessed with an adequate neurovascular examination and a thorough neurological examination. In pelvic fractures, management and treatment begins with ABCDE. Followed by stabilization of the patient, a multidisciplinary approach is required. External or internal fixation can be performed to stabilize the pelvis, its use and recommendation usually vary according to the characteristics of each fracture, the associated injuries and the instability of the pelvic ring. Pelvic trauma with involvement of the acetabulum and injuries to the genitourinary system should not be underestimated. Complications include infection, thromboembolism, malunion and pseudarthrosis. KEY WORDS: fracture, pelvis, pelvic ring, pelvic trauma.

PELVIC FRACTURES, EPIDEMIOLOGY, ANATOMY, MECHANISM OF INJURY, CLASSIFICATION, IMAGING PRESENTATION, CLINICAL PRESENTATION, MANAGEMENT AND COMPLICATIONS

Introduction: Open fractures of the pelvis represent one of the most fatal injuries within musculoskeletal trauma so they must be treated correctly, adjusting to a multidisciplinary approach to achieve the well-being of the affected person, in addition to restoring homeostasis and normal pathophysiology related to the mechanical stability of the pelvic ring. Objective: to detail current information related to pelvic fractures, epidemiology, anatomy, mechanism of injury, classification, imaging presentation, clinical presentation, management and complications. Methodology: a total of 27 articles were analyzed in this review, including review and original articles, as well as clinical cases, of which 20 bibliographies were used because the other articles were not relevant for this study. The sources of information were PubMed, Google Scholar and Cochrane; the terms used to search for information in Spanish, Portuguese and English were: fracturas de pelvis, fraturas do anel pelvico, anatomy of the pelvis, fractures of the pelvis. Results: Most cases of pelvic fractures occur in young people due to high-energy mechanisms, although injuries can also be generated by low-energy mechanisms and can cause fractures of individual bones. Mortality is higher in individuals with hemodynamic instability. The standard imaging examinations in trauma are anteroposterior projections of the thorax, lateral cervical spine and anteroposterior projections of the pelvis; special projections of the pelvis include the oblique alar and obturator projections. The severity of pelvic fractures is closely related to the associated injuries. Conclusions: Knowledge of anatomy is a fundamental piece in the treatment of pelvic fractures and associated injuries. There are several systems for classifying pelvic fractures, according to anatomical patterns, mechanisms of injury, resulting instability requiring surgery. The most frequently used is that of Young and Burgess. For evaluation, one should start with the ABCDE, airway, breathing, circulation, disability, and exposure and integrate a complete traumatologic evaluation. To determine whether there is pelvic instability, the anteroposterior and lateral compression test is performed for one occasion, generating internal and external rotation of the pelvis. The spine and extremities should be well assessed with an adequate neurovascular examination and a thorough neurological examination. In pelvic fractures, management and treatment begins with ABCDE. Followed by stabilization of the patient, a multidisciplinary approach is required. External or internal fixation can be performed to stabilize the pelvis, its use and recommendation usually vary according to the characteristics of each fracture, the associated injuries and the instability of the pelvic ring. Pelvic trauma with involvement of the acetabulum and injuries to the genitourinary system should not be underestimated. Complications include infection, thromboembolism, malunion and pseudarthrosis. KEY WORDS: fracture, pelvis, pelvic ring, pelvic trauma.

Ultrauniform Ru Nanoclusters as Efficient Hydrogenation Catalysts for Phthalates

Cyclohexane dicarboxylic acid (CHDA) ester, a kind of environmental-friendly plasticizer, can be produced by phthalates hydrogenation. However, the synthesis of catalysts with high activity and selectivity is a challenge due to the stability of aromatic rings. In this work, a series of ultrauniform Ru nanoclusters supported by γ-Al2O3 are synthesized for the hydrogenation of diisononyl phthalate (DINP). Results show that the conversion of DINP and the selectivity of diisononyl-cyclohexane-1,2-dicarboxylate (DINCH) both reach 100% at 140 °C and 3 MPa H2 pressure. Diisononyl-cyclohexene-1,2-dicarboxylate (4H-DINP) and 1,2-cyclohexanedicarboxylate-7-methyloctyl ester are found; the hydrogenation reaction network of DINP is constructed. Alkali metal ions adsorbed on the surface of Ru nanoclusters prepared by the polyol method can stabilize Ru3+-Hδ− species by electrostatic interaction, thus affecting the hydrogenation activity of the catalyst, following the order of Li+ > Na+ > K+ > Cs+. Ru-based catalysts prepared by the polyol method have good prospects for application in phthalates hydrogenation.

Survival and dynamics of rings of co-orbital planets under perturbations

ABSTRACT In co-orbital planetary systems, two or more planets share the same orbit around their star. Here we test the dynamical stability of co-orbital rings of planets perturbed by outside forces. We test two setups: (i) ‘stationary’ rings of planets that, when unperturbed, remain equally spaced along their orbit and (ii) horseshoe constellation systems, in which planets are continually undergoing horseshoe librations with their immediate neighbours. We show that a single rogue planet crossing the planets’ orbit more massive than a few lunar masses ($0.01\!-\!0.04 {\rm \, M_\oplus }\!\!$ ) systematically disrupts a co-orbital ring of 6, 9, 18, or 42 Earth-mass planets located at 1 au. Stationary rings are more resistant to perturbations than horseshoe constellations, yet when perturbed they can transform into stable horseshoe constellation systems. Given sufficient time, any co-orbital ring system will be perturbed into either becoming a horseshoe constellation or complete destabilization.

Feed Curves for Controlling Ring Rolling Stability in Large-Scale Flat Ring Rolling Process.

Due to the large wall thickness difference and serious instability in the large-scale ring rolling process, most studies on the feed curve are not suitable for a large-scale ring. The production cost of the large-scale ring is high, and if plastic instability occurs, it will cause a great waste of resources. Therefore, in this study, a staged feed strategy based on the evolution of ring instability is proposed with the objective of controlling the rolling stability of a large-scale ring. Firstly, based on the law of rolling instability evolution, the rolling stage during the rolling process is divided. Secondly, the coordination of all rolling stages is proposed as a factor to design the feed curve. The feed scheme is determined using the central composite design (CCD) method, and then the established mathematical model is applied to obtain the radial feed curves of a large-scale flat ring with a 5 m diameter for different schemes. Next, the designed feed curve was submitted to finite element method (FEM) simulation. According to the FE simulation results, a rolling map for controlling roundness error, eccentricity and vibration is established. Finally, the feed curve in the stable region is input to the FE simulation and the production trial to obtain the results of roundness error, eccentricity and vibration. A comparison of the simulation and production trial results shows that they are in good agreement, which proves the reliability of the feed curve designed based on the stable rolling region in the roll map. Moreover, the machining amount for both the simulation and production trial is below the maximum machined value.

Study on the Hydrodynamic Performance and Stability Characteristics of Oil-Water Annular Flow through a 90° Elbow Pipe

The transportation of highly viscous oil surrounded by water annulus has been recognized as a feasible option in terms of low-energy consumption and high efficiency. During the process of heavy oil delivery, the problem of pipe fittings is inevitably encountered, and the most common one is elbow assembly. In this present study, simulations for oil-water core annular flow (CAF) through a 90° elbow pipe were performed by computational fluid dynamics (CFD) based on VOF, standard k-ε, and CSF models. Simulation results were consistent with experimental data, which verifies the validity and practicability of the proposed model. The effects of inlet water fraction, superficial velocities of oil and water, oil properties (density and viscosity), and pipe geometry-related parameters (diameter ratio, wall roughness, and surface wettability) on the hydrodynamic performance and stability characteristics were explored. It is revealed that inlet water fraction, superficial velocities of oil and water, oil properties, and pipe geometric parameters do influence the volume fraction of oil and the stability of the water ring. Furthermore, the oil core may adhere to the downstream of the 90° elbow pipe under certain operational conditions. The results could provide a reference for the design of 90° elbow pipe structures and the optimization of operation parameters.

The relationships between direct substituents, aromaticity and kinetic stability of pentazole ring

The two directly substituted pentazoles, N5NH2 and N5COOH, were designed to theoretically study the relationships between substituents, aromaticity and kinetic stability thereof. Analysis shows their kinetic stability order described by the energy separations between the highest occupied molecule orbital (HOMO) and the lowest unoccupied molecule orbital (LUMO), viz. HOMO-LUMO gap, is line with the aromaticity orders obtained from nucleus-independent chemical shift (NICS), harmonic oscillator measure of aromaticity (HOMA), Bird aromaticity index (I) and isochemical shielding surface (ICSS), which is N5NH2 > N5COOH. But this order is contrary to the heat stability order according to Ref [1] The inconsistency between heat stability and kinetic stability reveals the fact that stability of compounds is a complex character and different according to the compound property of the study. The consistency of kinetic stability order with the aromaticity orders described by NICS, NICSSZZ, HOMA, I and ICSS indicates these widely accepted methods for aromaticity estimating are reliable for the two given compounds. As for the effect on aromaticity of pentazole ring from substituent, electron-donating substituent have stronger effect than electron-withdrawing substituent.

C-Terminal-Modified Oligourea Foldamers as a Result of Terminal Methyl Ester Reactions under Alkaline Conditions.

Hybrids of short oligourea foldamers with residues of α, β and γ-amino acids esters at the C-terminus were obtained and subjected to a reaction with LiOH. There are two possible transformations under such conditions, one of which is ester hydrolysis and the formation of a carboxylic group and the other is the cyclization reaction after abstraction of a proton from urea by a base. We have investigated this reaction with difference C-terminal residue structures, as well as under different work-up conditions, especially for oligourea hybrids with α-amino acid esters. For these compounds, an oligourea-hydantoin combination is the product of cyclization. The stability of the hydantoin ring under alkaline conditions has been alsotested. Furthermore, this work reports data related to the structure of C-terminal-modified oligourea foldamers in solution and, for one compound, in the solid state. Helical folding is preserved both for cyclized and linear modifications, with oligourea-acid hybrids appearing to be more conformationally stable, as they are stabilized by an additional intramolecular hydrogen bond in comparison to cyclic derivatives.

Editorial

Editorial