Intensity Of Response Research Articles

Multi-Level Numerical Modelling and Analysis of Tile Vaults

The complex structural behaviour of masonry, with its brittle response in tension, frictional response in shear, and anisotropy, makes it challenging to model accurately. Tile vaults, with their unique features such as different binders and bricks placed flat, have distinctive structural performance, and determining the most suitable assessment method is still a subject of debate in both academic and professional circles. This paper presents a study on the structural analysis of tile vaults, aiming at evaluating different numerical approaches for this type of structure. The examination of these approaches and their effectiveness in capturing the structural behaviour of tile vaults intends to offer valuable insights to researchers and professionals in this field. Experimental research was initially carried out in order to provide data for the calibration of the structural models. Two full-scale vaults were tested. Furthermore, several material characterization tests were also performed. The numerical assessment was carried out through limit analysis and non-linear static analysis with numerical models based on the Finite Element Method (FEM). Two FEM models were prepared using different modelling approaches for masonry, namely the macro-modelling and the simplified micro-modelling approaches. The results of the limit analysis presented a load capacity significantly lower than the ultimate load obtained from the experimental tests. The calibrated FEM models presented good results in comparison to the experimental results, namely in terms of damage pattern and load capacity.

Seismic response analysis of submerged floating tunnel considering non-uniform excitation and flexible-support boundary effect

In order to ensure the safety of submerged floating tunnel(SFT) during operation, it is necessary to carry out SFT response analysis under environmental loads. Given that SFTs are often constructed in valley areas situated in seismic zones, the aseismic performance of SFT needs to be investigated. However, there are important factors of non-uniform excitation and flexible-support boundary which have not been explored thoroughly. Non-uniform excitation affects the load input characteristics while flexible-support boundary affects the dynamic characteristics of structure itself. In this paper, we built a multi-point seismic wave synthesis model which fits well with the target power spectrum and a numerical response analysis model which reflects the dynamic characteristics of SFT structure well. The results based on the proposed model show that vertical non-uniform excitation can significantly increase the peak value of SFT tether tension and tube displacement with flexible-support boundary under whether artificial or natural seismic wave series input. While flexible-support boundary can availably produce vibration control effect on peak value of tether tension and tube response of whether displacement or stress indices under non-uniform wave series input. This work can provide reference for dynamic safety assessment and vibration control design of SFT to improve the development of ocean space.

Asymmetry of tensile versus compressive elasticity and permeability contributes to the regulation of exchanges in collagen gels.

The Starling principle describes exchanges between blood and tissues based on the balance of hydrostatic and osmotic flows. However, the permeation properties of the main constituent of tissues, namely, collagen, in response to the stress exerted by blood pressure remain poorly characterized. Here, we develop an instrument to determine the elasticity and permeability of collagen gels under tensile and compressive stress based on measuring the temporal change in pressure in an air cavity sealed at the outlet of a collagen slab. Data analysis with an analytical model reveals a drop in the permeability and enhanced strain stiffening of native collagen gels under compression versus tension, both effects being essentially lost after chemical cross-linking. Furthermore, we report the control of the permeability of native collagen gels using sinusoidal fluid injection, an effect explained by the asymmetric response in tension and compression. We lastly suggest that blood-associated pulsations could contribute to exchanges within tissues.

A discrete dislocation dynamics framework for modeling polycrystal plasticity with hardening

A two-dimensional discrete dislocation dynamics (DDD) framework is extended to model plastic deformation in polycrystalline materials having realistic grain morphology in finite geometries. The formulation includes constitutive rules to represent intra-grain dislocation mechanisms as well as dislocation/slip transmission across grain boundaries. Rules for intra-granular interactions mimic key three-dimensional dislocation mechanisms, such as line tension and dynamic junction and source formation, in addition to other short-range dislocation interactions. Various effects of idealized three-dimensional dislocation mechanisms on the mechanical response in tension are explored. The scaling of flow strength with grain size is investigated with and without slip transmission at grain boundaries. To aid in the analysis, spatial mappings of relevant stress components and geometrically necessary dislocation density are produced, which bring out competing dislocation-based strengthening mechanisms leading to the observed grain size effect in polycrystals.

A physically-based hydrostatic strain energy model for rubber-like materials inspired by Flory-Orwoll-Vrij equation of state theory

In a compressible hyperelastic model for rubber-like materials, the strain energy function is generally composed of the hydrostatic part corresponding to changes in interchain interactions and the compressible elastic part attributable to the network structure. It is well known that the hydrostatic part dominates the compressibility of the material. In this study, inspired by the Flory-Orwoll-Vrij (FOV) equation of state (EOS) theory for pure polymer liquids (note: a cell-like EOS theory), we assume that (i) the compressibility of rubber-like materials corresponds to changes in free volume of polymer chain segments; (ii) the hydrostatic strain energy of a rubber-like solid is attributable to changes in interchain interaction energy and chain segments’ external motion degrees of freedom (the latter solely depends on interchain forces). With a focus on the reversible isothermal deformation process, we construct a physically-based hydrostatic strain energy function based on the Helmholtz free energy formulation in FOV EOS theory. With a view towards applications, we provide a specific compressible hyperelastic model by incorporating the new hydrostatic strain energy function and compressible eight-chain model, where the latter is utilized as the elastic part of the strain energy function. Our model is capable of predicting various volume data of rubber-like materials from the literature, such as the nonlinear pressure-volume response at finite volume changes in hydrostatic compression (HC), the volume change-stretch and stress-stretch data in uniaxial tension (UT), and the stress-volume data in constrained uniaxial compression (CUC). Given the severely limited volume change data for finite stretches in UT and other modes of deformation, we simulate the volume change-volume modulus-stretch responses in UT, equibiaxial tension (ET), pure shear (PS), and uniaxial compression (UC) over their respective theoretical range of stretch and successfully predict some available (qualitative) experimental observations. Together with the simulations of the volume change-stretch responses in UT, ET, PS, and UC based on the Ogden’s and Bischoff et al.’s compressible models, we summarize the characteristics of these responses and analyze the possible deformation mechanisms. These simulations can provide some guidance for future corresponding experiments. Finally, we analyze the deformation mechanisms of HC, CUC, UT, ET, PS, and UC by simulating the responses for total strain energy and its components. This study provides a new physical picture and corresponding theoretical model for the hydrostatic strain energy function of rubber-like materials and finally proposes the general research strategy for constructing new hydrostatic strain energy functions based on the EOS theories for pure polymer liquids.

Numerical estimation via remeshing and analytical modeling of nonlinear elastic composites comprising a large volume fraction of randomly distributed spherical particles or voids

We investigate numerically via finite element (FE) simulations and analytically the nonlinear behavior of a soft matrix comprising a large volume fraction (up to 55%) of monodisperse spherical inclusions, which can be either rigid particles or voids. To address the issue of severe mesh distortion at large strains, we employ a successive remeshing and solution mapping technique that allows us to achieve a large macroscopic deformation, with the maximum attained stretch being at least two to three times when compared to that without remeshing. A general algorithm allowing to read complex arbitrary particle geometries is proposed and implemented allowing to remesh a finitely strained domain with randomly distributed inclusions of arbitrary shape. The present simulation results for a neo-Hookean elastic matrix filled with rigid particles show that the nonlinear stress–stretch uniaxial tension response can be well approximated by a neo-Hookean material with an effective shear modulus that depends on the volume fraction of the inclusions. Additionally, a study of the number of particles demonstrates that sixty four monodisperse spheres is a good compromise to reach accurate results for large deformations and maintain a reasonable CPU-time. The FE data serve as a powerful assessment tool for analytical homogenization models. Newly developed and existing models for small and large strains are proposed and assessed, respectively, for both rigid particles and voids. These results fill the gap for large volume fractions of inclusions and serve as a reference for the homogenization of the microstructures of interest.

Exploring Characteristics of Self-Defining Memories in Older Adults.

The aim of this descriptive study was to investigate the Self-Defining Memories (SDMs) in a large sample of 181 older adults (65-90 years; mean age = 73.0 years) and to target the relationships between their different dimensions. The sampling method was nonprobabilistic, based on voluntary participation. Participants were asked to recall three SDMs. They also completed the Mini-Mental State Examination, the Hospital Anxiety and Depression Scale, and a Self-esteem Scale. Almost half of the SDMs were specific and more than a quarter were integrated. Specificity, tension, redemption, contamination sequences, and affective response varied regarding thematic content. Specificity was positively correlated to tension whereas autobiographical reasoning was positively correlated to redemption and negatively linked to emotional response and depression. This research highlighted that identity is constituted by the main types of events that make up a life: interpersonal relationships, life-threatening events, achievement, and leisure.

Time series prediction based on LSTM neural network for top tension response of umbilical cables

The umbilical cable is an essential component of offshore oil and gas extraction systems. The severe marine environment poses a high challenge to the safety of the umbilical cable structure during operation. The analysis of an umbilical cable requires complex and resource-demanding finite element time-domain simulations to obtain their nonlinear dynamic response. Therefore, in order to solve the problem of structural safety monitoring and real-time assessment of remaining life of umbilical cables under extreme sea states, there is a great need to predict the dynamic response of umbilical cables quickly and accurately during operation, for ease of making fast decisions for system operation and maintenance before the arrival of extreme sea states. Given the strong nonlinear function-approximation ability of the neural network, this study proposes an efficient method for the prediction of the time series of umbilical cable top tension response based on LSTM (long short-term memory) neural network. We use LSTM neural network and ARIMA (autoregressive integrated moving average) model in a real engineering case for time series prediction of the top tension response of the umbilical cable, and the results of the two models are analyzed and compared, and the efficiency and accuracy of the LSTM neural network model are verified. Furthermore, the hyperparameter, dataset and generalization ability of LSTM model are discussed. The results indicate that feasibility of the tension response prediction of umbilical cables under dynamic load in complex marine environments.

Conceptual design, parameter optimization and performance investigation of a 10MW semi-submersible floating wind turbine in shallow water

There is lacking of floating wind turbine supporting large wind turbine, i.e. 10 MW, aiming at shallow water applications. In this paper, a 10 MW semi-submersible floating wind turbine named OUCwind is proposed for shallow water, and a scale optimization procedure is proposed during the preliminary design stage. It offers an engineering-practical method to determine the main parameters of a new-proposed floater, and critical floater characteristics, such as floater stability, natural period, platform mass etc. are chosen as important design criteria. The hydrodynamic performance with different scale parameters are investigated and it is found that enlarging distance between columns is a cost-effective way to get better stability and hydrodynamic performance. The structural performance of the new-designed OUCwind floater are compared with other two well-known braceless 10 MW platforms, 10 MW-CSC, and OO-star. From the frequency-domain analysis results, the surge linear transfer function, mean drift force and quadratic transfer function near the surge natural frequency of OUCwind is relatively small compared with other two platforms. In the time domain, the new-designed OUCwind also performs better in surge motion and mooring line tension response compared with 10 MW-CSC and OO-star, especially under extreme condition. Nevertheless, for the heave and pitch motions, the wave-frequency response of the OUCwind platform is relatively large under extreme load conditions.

Early committed polarization of intracellular tension in response to cell shape determines the osteogenic differentiation of mesenchymal stromal cells.

Within the heterogeneous tissue architecture, a comprehensive understanding of how cell shapes regulate cytoskeletal mechanics by adjusting focal adhesions (FAs) signals to correlate with the lineage commitment of mesenchymal stromal cells (MSCs) remains obscure. Here, via engineered extracellular matrices, we observed that the development of mature FAs, coupled with a symmetrical pattern of radial fiber bundles, appeared at the right-angle vertices in cells with square shape. While circular cells aligned the transverse fibers parallel to the cell edge, and moved them centripetally in a counter-clockwise direction, symmetrical bundles of radial fibers at the vertices of square cells disrupted the counter-clockwise swirling and bridged the transverse fibers to move centripetally. In square cells, the contractile force, generated by the myosin IIA-enriched transverse fibers, were concentrated and transmitted outwards along the symmetrical bundles of radial fibers, to the extracellular matrix through FAs, and thereby driving FA organization and maturation. The symmetrical radial fiber bundles concentrated the transverse fibers contractility inward to the linkage between the actin cytoskeleton and the nuclear envelope. The tauter cytoskeletal network adjusted the nuclear-actomyosin force balance to cause nuclear deformability and to increase nuclear translocation of the transcription co-activator YAP, which in turn modulated the switch in MSC commitment. Thus, FAs dynamically respond to geometric cues and remodel actin cytoskeletal network to re-distribute intracelluar tension towards the cell nucleus, and thereby controlling YAP mechanotransduction signaling in regulating MSC fate decision. STATEMENT OF SIGNIFICANCE: We decipher how cellular mechanics is self-organized depending on extracellular geometric features to correlate with mesenchymal stromal cell lineage commitment. In response to geometry constrains on cell morphology, symmetrical radial fiber bundles are assembled and clustered depending on the maturation state of focal adhesions and bridge with the transverse fibers, and thereby establishing the dynamic cytoskeletal network. Contractile force, generated by the myosin-IIA-enriched transverse fibers, is transmitted and dynamically drives the retrograde movement of the actin cytoskeletal network, which appropriately adjusts the nuclear-actomyosin force balance and deforms the cell nucleus for YAP mechano-transduction signaling in regulating mesenchymal stromal cell fate decision.

Who Drinks Bubble Tea? Coethnic Studentification in Toronto’s Chinatown

This article examines studentification in Toronto’s Chinatown, a centrally located neighborhood experiencing increases in student populations due to nearby university expansion. This expansion has been met with land-use planning policies of intensification and containment, and market-driven development propelling substantial density increases. We seek to answer, first, what types of development and residential trends result from rising student housing demand; second, how are commercial uses influenced by a growing student population of young, largely racialized adults and their lifestyle choices; and, third, what types of neighborhood tensions and micropolitics play out in this context. We show that the growing university intake of international students—particularly from China—living near Chinatown has created class-based and generational tensions in response to coethnic and market-driven neighborhood change. We highlight opportunities for multistakeholder collaborations to preserve Chinatown as an affordable intergenerational neighborhood where residents (old and new) find communities of arrival and belonging.

Mooring tension assessment of a single line kelp farm with quantified biomass, waves, and currents

While the number of kelp farms have steadily increased, few have been deployed with sensors to measure mooring tensions with substantial biomass. During the kelp farming season of 2018–2019 in Saco Bay, Maine USA, a field study was conducted to assess mooring loads due to environmental conditions and kelp growth. The effort included the deployment of a farm with a 122 m cultivation line and spread mooring with rope, chain, and anchors in 15.2 m of water. The system was deployed with seeded twine in late November and harvested in May. In April, with kelp biomass estimated at 7.8 kg m−1, two load cells were installed to measure mooring tensions in response to currents and waves. The currents and waves were measured with two Acoustic Doppler Current Profilers deployed adjacent to the load cells. From these measurements, we characterized the maximum loading case in response to a complex hydrodynamic environment. The maximum tension occurred on the landward side of the farm even though wave exposure was seaward. The tension in the landward side mooring was dominated by steady drag from the currents going to the east southeast. During this event, the two profilers were positioned on the leading and trailing edges of the farm relative to the prevailing current direction. Velocities measured at 0.5 m bins showed a 26.7% reduction at the depths where the kelp was located. To analyze the dynamic portion of the load cell datasets, the oscillatory components were processed into energy density spectra. Results showed that mooring tensions were not affected by waves at frequencies greater than 0.175 Hz, with most of the energy occurring near 0.12 Hz. The tension spectra did reveal energy at frequencies between 0.0075 and 0.01 Hz, indicating a low frequency response, possibly due to nonuniform velocity profiles inducing vertical motion of the cultivation line. It was also observed that the landward mooring, subjected to higher currents, was more sensitive to oscillating loads than the slack seaward side. The high-fidelity dataset will be useful for numerical modeling validation to further understand these dynamics and to optimize kelp farm designs.

Excitatory cholinergic responses in mouse primary bronchial smooth muscle require both Ca2+ entry via l-type Ca2+ channels and store operated Ca2+ entry via Orai channels

Malfunctions in airway smooth muscle Ca2+-signalling leads to airway hyperresponsiveness in asthma and chronic obstructive pulmonary disease. Ca2+-release from intracellular stores is important in mediating agonist-induced contractions, but the role of influx via l-type Ca2+ channels is controversial. We re-examined roles of the sarcoplasmic reticulum Ca2+ store, refilling of this store via store-operated Ca2+ entry (SOCE) and l-type Ca2+ channel pathways on carbachol (CCh, 0.1–10 µM)-induced contractions of mouse bronchial rings and intracellular Ca2+ signals of mouse bronchial myocytes. In tension experiments, the ryanodine receptor (RyR) blocker dantrolene (100 µM) reduced CCh-responses at all concentrations, with greater effects on sustained rather than initial components of contraction. 2-Aminoethoxydiphenyl borate (2-APB, 100 μM), in the presence of dantrolene, abolished CCh-responses, suggesting the sarcoplasmic reticulum Ca2+ store is essential for contraction. The SOCE blocker GSK-7975A (10 µM) reduced CCh-contractions, with greater effects at higher (e.g. 3 and 10 µM) CCh concentrations. Nifedipine (1 µM), abolished remaining contractions in GSK-7975A (10 µM). A similar pattern was observed on intracellular Ca2+-responses to 0.3 µM CCh, where GSK-7975A (10 µM) substantially reduced Ca2+ transients induced by CCh, and nifedipine (1 µM) abolished remaining responses. When nifedipine (1 µM) was applied alone it had less effect, reducing tension responses at all CCh concentrations by 25% - 50%, with greater effects at lower (e.g. 0.1 and 0.3 µM) CCh concentrations. When nifedipine (1 µM) was examined on the intracellular Ca2+-response to 0.3 µM CCh, it only modestly reduced Ca2+ signals, while GSK-7975A (10 µM) abolished remaining responses. In conclusion, Ca2+-influx from both SOCE and l-type Ca2+ channels contribute to excitatory cholinergic responses in mouse bronchi. The contribution of l-type Ca2+ channels was especially pronounced at lower doses of CCh, or when SOCE was blocked. This suggests l-type Ca2+ channels might be a potential target for bronchoconstriction under certain circumstances.

Vidminnist pokaznykiv boliu, tryvohy, depresii ta kontsentratsii kortyzolu v syrovattsi krovy u patsiientiv iz hostrym i khronichnym perebihom vertebrohennoho poperekovo-kryzhovoho bolovoho syndromu

Introduction. Pain is classified as acute and chronic. Acute pain implies a painful condition with a rapid onset or of a short course, whereas chronic pain is referred to as a painful condition persisting beyond the normal time of healing. Chronic low back pain has also been correlated with stress-induced inflammation. Psychological distress aggravates pain symptoms and pain induces a stress response in the body by releasing cortisol from the adrenal cortex. The aim of the study. To investigate differences in levels of anxiety, depression, and cortisol blood concentration in patients with acute and chronic vertebral-sacral pain syndrome. Our main goal was to encrease our understanding of the development and persistence of acute and chronic back pain, define risk factors and improve treatment strategies for the patients. Materials and methods: We studied cortisol levels in blood plasma, levels of anxiety and depression in patients with back pain and LV-SI intravertebral disk herniation. The group under investigation included 125 patients, including 65 patients with acute, and 60 with chronic pain syndrome. A Visual Analogue Scale (VAS) was used to measure the patient`s pain assessment. Spielbergʼs anxiety test is designed to assess reactive and personal anxiety. Personal anxiety characterizes the degree of a person’s anxiety and emotional tension due to the action of stress factors in general. Reactive anxiety is a patient’s personal condition, which characterizes the degree of his anxiety, and emotional tension in response to the action of a stress factor. The Beck’s Depression Symptoms Questionnaire (BDSQ) includes 21 item, self-report rating inventory that measures characteristic attitudes and symptoms of depression. Results. We found no significant difference according to VAS between groups, at the time of hospitalization, patients in the acute pain group evaluated their pain as 7.15 ± 1.17 points, while in the chronic pain group it was estimated as 6.08 ± 0.96 points (p-value more than 0.05). The concentration of cortisol in blood plasma in the acute pain group patients was 313.3 ± 87.7 mmol/l, and in the chronic pain group – 450.7 ± 121.9 mmol/l, the difference between the groups was insignificant (p-value more than 0.05). The evaluation according to Spielbergʼs anxiety test demonstrated high anxiety levels at the time of examination: in the acute pain group reactive anxiety corresponded to 40.4 ± 12.6 points, in the chronic pain group the same index was 39.5 ± 11.3. Personal anxiety in the group of acute pain was 32.3 ± 13.6, in the group of chronic pain – 41.3 ± 9.7. According to Beck’s Depression Symptoms Questionnaire before the beginning of treatment average score in the acute pain group was estimated as 6.8 ± 1.1 points, while in the chronic pain group this index corresponded to 9.8 ± 0.8 points (probable difference between groups p-value less than 0.05). Comparisons of cortisol concentrations between groups of patients with different levels of pain, anxiety, and depression demonstrated no significant differences. However, cortisol level was higher in the acute pain group among patients who rated their pain syndrome as ʺsevere painʺ (6-7 points according to VAS) (280.2 ± 77.8 mmol/l in the group of acute pain, and 515.0 ± 80.1 mmol/l in the group of chronic pain), as well as among patients with mild depressive symptoms (393.5 ± 19.5 mmol/l in the group with an acute pain compared to 553.1± 68.0 mmol/l in the group with chronic pain syndrome). Conclusions. The study demonstrates differences in pain perception and assessment in patients that suffer from acute and chronic back pain. A high level of personal and reactive anxiety was found among participants. A higher level of depressive symptoms, as well as the disturbances in the diurnal fluctuations of cortisol were detected in the chronic pain group patients.

ATTENUATION OF LARYNGOSCOPY AND ENDOTRACHEAL INTUBATION-INDUCED SYMPATHOMIMETIC RESPONSES WITH INTRAVENOUS ESMOLOL AND LIGNOCAINE: A COMPARATIVE STUDY

Introduction: Direct laryngoscopy and endotracheal intubation are a noxious stimulus and induces sympathomimetic responses. Although properly tolerated in normal and healthy subjects, it can impose serious arrhythmias, left ventricular failure, myocardial ischemia, or rupture of cerebral aneurysm in vulnerable patients. Various techniques are currently working to attenuate this response, but, so far, none of them have been proven to be superior. Esmolol and Lignocaine; attenuate those responses however are related to some untoward outcomes such as bradycardia and hypotension. In low doses, the chances of those expected untoward outcomes are relatively low. Aim and Objectives: We designed this prospective clinical education to assess and compare the efficacy of intravenous Esmolol and Lignocaine in attenuating sympathomimetic responses to laryngoscopy and endotracheal intubation. Methods: After the Institutional Ethics Committee approval, 52 consenting patients of ASA physical repute I or II of age between 20 and 60 years, scheduled for surgeries requiring general anesthesia, remained randomly owed to two groups; Group E and Group L, given 2 mg/kg of inj. Esmolol intravenously and inj. Lignocaine 2 mg/kg, respectively, 2 min before intubation. Final outcome variables such as heart rate (HR), systolic blood pressure (BP), diastolic BP, and mean arterial pressure (MAP) had been recorded and compared between the two groups immediately after intubation (AI) and then at 1, 3, and 5 min AI. Results: There was no statistically huge distinction regarding the demographic profiles of both the study groups. There has been a substantial rise in mean HR in the lignocaine group all through laryngoscopy and intubation, which did not settle to baseline level even after 5 min (p<0.0001). In the esmolol group, a significant attenuation of HR was observed immediately AI and 1, 3, and 5 min following intubation. MAP was well controlled in the esmolol group. Throughout the study period, readings of mean arterial pressure were much higher in esmolol group. In the lignocaine group, the values of study parameters were higher than the baseline at every point of time. Diastolic BP was elevated in both groups. Conclusion: Esmolol was found to be more effective for attenuation of hemodynamic tension response to laryngoscopy and intubation when compared with Lignocaine. However, Lignocaine is also safe and effective to some extent.

Non-linear elastic tension–compression asymmetric anisotropic model for fibre-reinforced composite materials

We present a novel constitutive model capable of describing non-linear anisotropic fibre-reinforced materials with different responses in tension and compression under a general stress state. The model is based on the original one-dimensional Ramberg–Osgood model, which is generalized to a multiaxial stress state and anisotropic material behaviour under thermodynamic requirements. To account for tension–compression asymmetry under a multiaxial stress state, the model is extended by the use of the stress triaxiality invariant as an indicator of stress state type, e.g. shear, uniaxial or biaxial tension, compression, etc. The model is implemented in ABAQUS/Explicit via the VUMAT subroutine and verified on two material datasets, which are an S2-glass/E773-epoxy and a reinforced polyester composite material. In comparison with other models, the proposed model provides an elegant formulation for the description of all the aforementioned phenomena, resulting in a simple calibration procedure based on uniaxial tensile and compressive tests.

Evaluation of Local Application of Glucosamine Sulfate and Chondroitin Sulfate on Temporomandibular Joint Response and Alleviation of Pain and Tension During the Functional Treatment of Skeletal Class II Patients: A Randomized Control Clinical Trial.

This study was conducted to assess the effects of applying a gel ofcombined glucosamine sulfate and chondroitin sulfate on the temporomandibular joint (TMJ) area in patients with skeletal Class II malocclusion treated by removable functionalappliances in terms of TMJ internal proportions, levels of pain, and tension. The study included 36 patients aged 10-13 years with skeletal Class II malocclusion due to retrusion of the mandible characterized by:4-8 degrees of the sagittal skeletal discrepancy (ANB) angle,4-7 mm of overjet,72-76 degrees of the sagittal mandibular positioning (SNB) angle, and a bone maturity stage locatedat pubertal growth spurt. Patients were distributed to the experimental group (Twin-Block appliance + Jointance®gel)or thecontrol group (conventional treatment with the Twin-Block appliance). An allocation ratio of 1:1 was employed. Pre- and post-treatment digital lateral cephalometric radiograms were taken, and the TMJ joint spaces were measured using the Viewbox software (dHAL Software, Kifissia, Greece). The pain and discomfort levels were evaluated using a questionnaire with a four-point Likert scale at three assessment times. The anterior and posterior glenoid and anterior condylar distances to the pterygoid vertical (PTV) reference planesignificantly decreased after treatment (p<.001), and the anterior joint space decreased significantly (p<.001). In contrast, the superior distance of the condyle to the Frankfort horizontal reference planeincreased significantly after treatment, and the same results were found for the posterior and superior joint spaces (p<.05). There were no significant differences between the two groups in the evaluatedlinear variables. No significant differences were found when comparing pain and tension levels between the two groups at each assessment time. A gradual decrease in pain and tension levels was observed between the three evaluation times in both groups. A combinationof glucosamine sulfate and chondroitin sulfate did not affect the temporomandibular joint spaces, pain, and tension levelsin patients with skeletal Class II malocclusions treated by removable functional appliances.

Numerical and experimental research on the coupled motion responses of a Spar platform with a tender vessel during drilling scenarios

During the drilling operation of a Spar platform with a tender semisubmersible platform, the motion of the floating platforms is complex and quite different from that of the separate conditions due to the influence of multibody hydrodynamics and the connecting system. This can lead to potential collision accidents. In this paper, the motion characteristics of a tender assistant drilling (TAD) system under drilling scenarios are analyzed numerically and experimentally. Based on three-dimensional potential flow theory, the numerical model of a multiple floating body system is established to obtain the hydrodynamic parameters, the first-order wave force, and the mean drift force, and then a time domain analysis is conducted. Both single-body and coupled multibody conditions are observed to analyze the motion performance of the gangway and the tension response of the connecting lines. The results show that the Spar platform affects the low-frequency motion of the semisubmersible platform more intensely when the platforms work side by side without hawser lines. The phenomenon of hydrodynamic interaction is weakened under fully coupled conditions due to this connection. In addition, the stroke of the gangway is positively related to the relative motion, which reflects the relative motion response of the platforms.

Constitutive modeling for the temperature-dependent stress-strain behavior of polymer-bonded composite materials

Accurate characterization of the tension and compression behavior of polymer-bonded composite materials (PBMs) under different temperatures is essential to understanding their mechanical properties and deformation. Therefore, this study proposed a stress-strain constitutive model to describe the deformation of PBMs, which is generalized and temperature-dependent. The uniaxial tension and compression response of material specimens prior to failure are studied in the temperature range of -40°C to 75°C. The test data demonstrate temperature dependence of the specimens and the corresponding stress-strain curves can be approximated as linear elastic and plastic parts. Based on the testing results, the Ramberg-Osgood type equation is used to describe stress-strain curves. Using the response surface model to fit the relation of parameter and temperatures, a general stress-strain model considering the temperature-dependent was developed. The model effectiveness is validated by using independent testing data and third-party data. Compared with the reference model, the proposed model yields smaller relative errors.

Stiff matrix induced srGAP2 tension gradients control migration direction in triple-negative breast cancer.

Rationale: Cells migrating through interstitial matrix enables stiffening of the tumor micro-environment. To overcome the stiff resistance of extracellular matrix, aggressive cells require the extracellular mechanosensory activation and intracellular tension response. Mechanotransduction linker srGAP2 can synergistically control the mechanical-biochemical process of malignant cell migration. Methods: To mimic the tumor micro-environment containing abundant collagen fibers and moving durotaxis of triple-negative breast cancer cells, the stiff-directed matrix was established. The newly designed srGAP2 tension probe was used to real-time supervise srGAP2 tension in living cells. The phosphorylation sites responsible for srGAP2 tension were identified by phosphorylated mutagenesis. Transwell assays and Xenograft mouse model were performed to evaluate TNBC cells invasiveness in vitro and in vivo. Fluorescence staining and membrane protein isolation were used to detect protein localization. Results: The present study shows srGAP2 serves as a linker to transmit the mechanical signals among cytoskeleton and membrane. SrGAP2 exhibits tension gradients among different parts in the stiff-directionally migrating triple-negative breast cancer cells. Cells showing the polarized tension that increased in the leading edge move faster, particularly guided by the stiff interstitial matrix. The srGAP2 tension-directed cell migration results from the upstream events of PKCα-mediated phosphorylation at Ser206 in the F-bar domain of srGAP2. In addition, Syndecan-4 (SDC4), a transmembrane mechanoreceptor protein, drives PKCα regional recruit on the area of membrane trending deformation, which requires the distinct extent of extracellular mechanics. Conclusion: SDC4-PKCα polarized distribution leads to the intracellular tension gradient of srGAP2, presenting the extra- and intracellular physiochemical integration and essential for persistent cell migration in stiff matrix and caner progression. Targeting the srGAP2-related physicochemical signaling could be developed into the therapeutic strategies of inhibiting breast cancer cell invasion and durotaxis.