Cross-sectional Ratio Research Articles

Chronic obstructive pulmonary disease features in patients visiting primary respiratory clinic and tertiary hospital in Japan

Pulmonologists in primary care clinics are positioned between those in tertiary hospitals and general practitioners in clinics and are anticipated to promote hospital-clinic collaboration for patients with chronic obstructive pulmonary disease (COPD). However, the clinical features of patients in primary respiratory clinics are unclear. This multicenter study cross-sectionally compared the characteristics of patients with COPD in a respiratory clinic (n = 69) with those in a university hospital (n = 124). More patients visited the clinic for symptom relief without a referral, whereas more visited the hospital for consultation of abnormal spirometry/computed tomography (CT). The patients in the clinic showed female predilection, higher prevalence of current smokers, severe dyspnea, and concomitant heart failure, and higher CT-measured cross-sectional area ratio of pectoralis muscle to adjacent subcutaneous adipose tissue compared to those in the hospital (all p < 0.05). The observed differences between the two groups suggest the need to establish the role of primary pulmonologists in hospital-clinic collaboration for better COPD management.

Axial compression behaviour of round-ended recycled aggregate concrete-filled steel tube stub columns (RE-RACFST): Experiment, numerical modeling and design

Round-ended recycled aggregate concrete-filled steel tube (RE-RACFST) column is an innovative composite member, which holds the advantage of round-ended concrete-filled steel tube (RE-CFST) and expands the application of RAC in structural members. This paper presents the testing and numerical investigation on the axial compression behaviour of RE-RACFSTs. A total of 18 stub columns were tested to determine the failure mode, axial load versus strain response, vertical and circumferential strains of the round-ended steel tube, and the confinement effect from external steel tube in different positions. The effects of cross-sectional aspect ratio, coarse recycled aggregate (CRA) replacement and steel ratio were analyzed. In general, the ductile behaviour of the specimens reduced with increasing aspect ratio and decreasing steel ratio. The confinement effect during the entire compression process was investigated based on the vertical and circumferential strains. Finite element (FE) models were then developed, and a constitutive model suitable for core RAC in RE-RACFST columns was proposed. Parametric analysis was then carried out to evaluate the effects of the aspect ratio, steel ratio, CRA replacement level, and material strength on the axial compression response. Finally, several existing design provisions for rectangular CFST and RAC-FST members were assessed the feasibility of their application in RE-RACFSTs by using the equivalent method.

단면분석을 통한 조선시대 상류주택 안마당의 시지각 특성에 관한 연구 - 경북지방 ‘ㅁ’자형 주택을 중심으로 -

The purpose of this study is to analyze the cross-sectional ratio of the courtyard, an external space that not only was used as a workplace, shelter, and playground in our lives, but also gave symbolic meaning to Koreans. Since the beginning of 2000, Hanok began to receive rapid attention from people, and Hanok construction and remodeling were actively carried out in urban and rural areas. In particular, Bukchon and Seochon in Seoul, around Cheonmachong in Gyeongju, and Hanok Village in Jeonju became popular places related to hanok, and Gyeongju, Buyeo, Gongju, and Iksan were designated as ancient districts to encourage the construction of hanok. However, although hanok is being built with national trends, support, and interest, attention is focused only on the external form, materials, and convenience of use, and the composition and system of the external space have not been properly reviewed. Therefore, this study aims to understand the functions and meanings of the yard in traditional housing, and to analyze the proportion of the height of the building surrounding the yard and the depth of the yard in terms of closure and opening. In addition, the system and characteristics of the external space of traditional architecture felt by this can be used as basic data in designing traditional architecture.

Variation of Acoustic Energy Across Sudden Area Expansions Sustaining a Subsonic Flow

The acoustic energy balance of a sudden area expansion is known to be altered in the presence of a mean flow. In this work, Ronneberger’s quasi-steady model describing the acoustic response of a sudden area expansion sustaining a subsonic mean flow of arbitrary Mach number is revisited using the acoustic absorption coefficient, shown to be a function of the inlet Mach number , cross-sectional area ratio , and upstream acoustic reflection coefficient . These analytical predictions are tested using a two-step numerical strategy, whereby the mean flow variables are obtained using Reynolds-averaged Navier–Stokes simulations and the fluctuating variables are computed using in-house linearized Navier–Stokes equations solvers. The agreement between the analytical model and the numerical results is found to be excellent for all geometries, mean flows, and acoustic boundary conditions investigated. The generation of acoustic energy by the flow expansion is observed analytically and numerically for high-Mach-number flows undergoing a slight sudden area increase for given acoustic boundary conditions. Conversely, it is found that substantial acoustic energy damping occurs across sudden area expansions characterized by a wide range of parameters . Moreover, entropy and vorticity fluctuations are found to be generated at the sudden area expansion, but entropy fluctuations are shown to have a negligible impact on the acoustic response of the area expansion at low and intermediate Mach numbers. Finally, the analytical model is found to be reasonably accurate up to Helmholtz numbers , corresponding to the frequency range of many industrial applications.

Alteration in the Cross-sectional Area (CSA) Ratio of the Paraspinal Muscles following Vertebral Insufficiency Fractures.

Background Vertebral insufficiency fractures in the elderly are associated with increased morbidity and mortality. Early diagnosis is essential to direct patient-specific rehabilitation. Aims We hypothesize that in patients with vertebral insufficiency fractures, there is atrophy of the psoas and paraspinal muscles with alteration in the cross-sectional area (CSA) of the muscles. Materials and Methods Magnetic resonance imaging (MRI) studies for 100 consecutive patients, older than 60 years presenting with lower back pain, were included in the study. For each MRI study, the CSA of the psoas and paraspinal muscles (multifidus) at the level of L4/5-disc space was measured to calculate the cross-sectional area ratio (CSAR) by two readers. One reader repeated the measurements after an interval of 2 weeks. We divided the patients ( n = 100) into various groups based on the number of vertebral fractures. Results In total, 77 patients with vertebral body fractures (48 with one, 16 with two and 13 with more than two fractures) were identified with a mean age of 73 (range 60-92) years. The ratio of multifidus CSA to psoas CSA was calculated with mean values of each group (1-4) as 2.56, 1.89, 2.09 and 2.16, respectively. There was statistically significance difference of the CSAR between the cohorts ( p -value = 0.0115). Conclusion Vertebral insufficiency fractures in the elderly are associated not only with atrophy of psoas and the multifidus group of muscles as evident by the CSA values, but they also affect the CSAR depending on the number of fractures. This finding may help to direct targeted patient-specific physiotherapy rehabilitation and interventions to prevent further such fractures.

Physics linkages between arterial stiffness, cerebrovascular flow and cognitive impairment

Background. Reduced cerebrovascular flow and localized hypoperfusion have been widely associated with various forms of cognitive impairment. Vascular cognitive impairment has also been associated with arterial stiffening and arteriosclerotic development. The linkages between cerebrovascular arteriosclerosis and localized cerebral ischemia, as dictated by the physics of fluid flow, while relatively unaddressed, are vascular contributions to cognitive impairment.&#x0D; Methods. The physics of fluid dynamics, particularly that of wave propagation in compliant vessels, was applied to the analysis of blood flow in a complex cerebrovascular tree, consisting of hundreds of thousands of arterial junctions. Each of these arterial junctions or bifurcations may partially reflect antegrade pulsatile flow into retrograde flow, resulting in reduced peripheral cerebral pulsatile flow.&#x0D; Results. The physics of fluid dynamics predicts1 that, at each bifurcation in the complex cerebrovascular maze, the percentage of antegrade flow which is reflected in retrograde flow is determined by the quotient of the arterial stiffnesses ratio and cross-sectional areas ratio on each side of each bifurcation. Physics predicts that, if the arterial stiffness/area ratios quotient is equal to unity then, ideally, there is no pulsatile retrograde flow. A ten percent pulsatile reflection would result from an arterial mismatch (in the quotation of trunk to branch artery stiffnesses to areas ratios) of about twenty percent. In other words, if a trunk artery at a bifurcation stiffens with aging by twenty percent relative to the bifurcations branch arteries, and the dimensions are unchanged, then the pulsatile antegrade flow reduces by about ten percent. In progressing from the extracranial arteries into the cerebral capillaries this pulsatile flow reduction process may be repeated at each bifurcation tier, causing an accumulating reduction in pulsatile flow into the capillaries. If the amplitude of the pulsatile retrograde flow is sufficiently large, the collision of the retrograde and antegrade pulsatile flows may result in transient flow reversal at select locations in the vascular bed. Such flow reversals may occur where a maximum in the retrograde flow pattern coincides with a minimum in the antegrade flow pattern, resulting in localized diastolic flow reversal. Persistent blood cell flow reversal, with its “scrubbing effect” on endothelial cells, combined with the flow’s associated pulse pressure amplification, may cause lifting of endothelial cells, thereby exposing the underlying intima and media to deposition of foreign materials, such as lipids and calcium. Hence, localized retrograde flow may induce arteriosclerotic development, which in turn, may increase bifurcation arterial stiffness ratios, which may further increase pulsatile flow reversals, increase arteriosclerotic development, decrease peripheral flow and increase arteriole ischemia at select cerebral locations.&#x0D; Conclusions. The physics of fluid dynamics predicts quantifiable cross-linkages between macro and microcirculation, as shown in Figure 1, which include age-related increases of localized arterial stiffness, cerebral ischemia and ultimately, parenchymal hypoxia.2,3 The specific cerebral locations of such hypoxia would be dependent on localized vascular and physiological conditions. The manifestation and nature of any cognitive impairment associated with localized hypoxia, would, therefore, also be dependent on localized vascular and physiological conditions.

Large-scale model test studies on a double-layer rubber dam

A new rubber dam with two layers of dam bodies anchored together into a rigid concrete base was proposed to improve the water-retaining capacity of a traditional rubber dam. A series of large-scale model tests was conducted to evaluate the static behaviour of a double-layer rubber dam under conditions of different internal and external water heads, anchoring distances and cross-sectional perimeters. It was found that the maximum tensile force of the Layer-1 dam is located at the anchoring point but that of the Layer-2 dam is located at the extruded free section. The optimal cross-sectional perimeter ratio was concluded as 0.8 with an optimal anchoring distance of 0.06 L1 and an internal water head in the upstream dam and in the downstream dam of 0.40 L1 and 0.36 L1, respectively, where L1 is the cross-sectional perimeter of the upstream dam.

Study on Mechanical Properties and Constitutive Relationship of Concrete Corroded by Hydrochloric Acid under Cyclic Load

Most of the existing studies on acid corrosion of concrete have focused on the mechanical behavior of concrete structures under monotonic load or without load. To investigate the mechanical properties of in-service concrete components under cyclic load in an acid corrosion environment, six groups of concrete prism specimens with different acid corrosion degrees (corrosion duration) were designed and prepared by the accelerated corrosion test method. The monotonic and cyclic axial compression load tests on these specimens were conducted to investigate the effects of corrosion degree on the mechanical properties of concrete specimens. The experimental results indicated that hydrochloric acid corrosion has obvious effects on the failure characteristics and mechanical properties of concrete. The surface of corroded concrete was easier to crack and spall under load, and the concrete spalling area enlarged as the acid corrosion duration increased. The compressive capacity of concrete specimens reduced rapidly with the increase in corrosion duration. The stress–strain envelope curves for concrete with different corrosion duration under cyclic load were essentially similar to that of concrete under monotonic load. The degradation rate of the descending section for the stress–strain curves of corroded concrete under cyclic load was much larger than that under the monotonic load due to the accumulation of internal damage in concrete. The peak strain and ultimate strain of corroded concrete increased significantly with the increase in corrosion duration and enhanced by 55.7% and 77.9%, respectively, compared with the uncorroded concrete, whereas the peak stress and elastic modulus rapidly decreased and reduced by 53.3% and 74.1%, respectively. Moreover, based on the strength degradation depth, the concept of effective bearing cross-sectional area ratio was proposed to characterize the corrosion degree of concrete, and the correction coefficient of descending section for the effective bearing cross-sectional area ratio was introduced to establish the constitutive model of corroded concrete under cyclic load, and the results calculated by this model matched well with the experimental values. The research in this paper can provide the experimental and theoretical basis for seismic life cycle and fatigue redesign of concrete structures in acid corrosion environments or coastal areas.

Thermal Behavior in the Inclined Space Connected to Fire Room

In this study, a model experiment was conducted to understand the effects of the parameters of the inclined space (cross-sectional aspect ratio and angle of incline) connected to the fire room on the hot gas flow in it. The trend of dimensionless temperature (&lt;i&gt;T*&lt;/i&gt;) decrease in the vertical direction of hot gas flow in the inclined space was found to not be related to the width of inclined space in the range of &lt;i&gt;T*&lt;/i&gt; &gt; 0.3. Additionally, the trend of temperature decrease in the direction of hot gas flow in the inclined space was found to not be related to the width of the inclined space. Furthermore, a certain temperature decrease trend was observed under each tilt angle.

Structural and Heat Transfer Model Analysis of Wall-Mounted Solar Chimney Inlets and Outlets in Single-Story Buildings

Wall-mounted solar chimneys use solar radiation to heat the air inside the chimney cavity and use thermal pressure to create natural convection. Applying this principle allows for the indoor ventilation of a building without energy consumption. However, in wall-mounted solar chimney designs, different air inlet and outlet design dimensions can have varying degrees of impact on the effectiveness of wall-mounted solar chimney ventilation. In order to analyze the internal airflow state and airflow temperature field distribution of wall-mounted solar chimneys, physical models of wall-mounted solar chimneys with six different air outlet-to-inlet cross-sectional area ratios were developed in this research work. Before numerical simulation analysis, heat transfer analysis of the wall-mounted solar chimney’s structural components and airflow channels was carried out, and corresponding mathematical heat transfer models were established. The internal flow state and temperature distribution characteristics of a wall-mounted solar chimney were analyzed by steady-state simulations using the computational fluid dynamics software, Ansys Fluent. Finally, transient simulation calculation analysis was conducted under six different S-value models to investigate the variation in the natural ventilation of a single-story building’s wall-mounted solar chimney for a whole day. The study showed that under the same simulation conditions, 80% ≤ S &lt; 100% effectively avoided the formation of vortices in the internal airflow of the wall-mounted solar chimneys and kept the ventilation effect of wall-mounted solar chimneys at a high level. The results of this study provide a reference for the optimization of research on the design of the air inlet and outlet structures of wall-mounted solar chimneys for single-story buildings.

Aluminium alloy channel columns: Testing, numerical modelling and design

Aluminium alloys can be employed in a wide range of structural applications offering high strength-to-weight ratio, whilst they can easily be extruded in various shapes. Channel (C-) sections have been increasingly employed as compression members, such as wall studs and chord members of roof trusses in framed residential and commercial buildings. However, relevant studies on their compressive behaviour are quite limited and thus a greater emphasis should be placed on providing a deeper understanding. Towards this direction, this paper examines the structural performance of C-sections under axial compression. An experimental and numerical investigation was performed on 6082-T6 heat-treated aluminium alloy C-section columns. In total, 6 fix-ended stub column tests were executed to examine the cross-sectional compressive behaviour, whilst 8 pin-ended column tests were conducted to study their minor-axis flexural buckling behaviour. The obtained experimental results were utilised to validate the developed finite element models. Subsequently, extensive parametric studies were carried out to generate additional performance data over a broad range of cross-sectional aspect ratios, and cross-sectional and member slendernesses. Both the experimentally and numerically obtained ultimate strengths are utilised to assess the accuracy of Eurocode 9 design provisions, including the flexural buckling curve. On the basis of the experimental and numerical results, a new flexural buckling curve is proposed improving the design accuracy. The applicability of the Direct Strength Method on the design of aluminium alloy C-sections subjected to axial compression is also evaluated resulting in the most accurate and consistent design strength predictions.

Suggestion of Practical Application of Discrete Element Method for Long-Term Wear of Metallic Materials

This study presents a simulation procedure for the wear of metallic materials exposed to long-term cumulative contact forces and introduces a numerical analysis procedure using the discrete element method (DEM) to predict the wear damage. Since the DEM can calculate the motion and contact load of each particle and the interaction between particles for each dynamic collision of particles, it was possible to analyze the motion of the particles causing metal wear. A method to reflect particle size, material properties, and long-term cumulative friction distance required by the DEM was proposed so that the collision and friction load between particles can be predicted practically. Considering the feature of wear suggested by Archard, it was shown that the wear amount can be predicted efficiently by converting the long-term load into an equivalent material constant. In addition, it was suggested that it is reasonable to determine the size of the particles in consideration of the size of the surface mesh of the metal surface. The accuracy of the analysis results obtained using the procedure proposed in this study was compared with that of the wear test results of metal material specimens presented by former studies. The numerical analysis was also performed in the reference study, but inaccurate results were derived compared to the analysis results. The reason for the inaccuracy of the numerical model performed in the previous study was found to be environmental factors that cannot be considered in a numerical analysis. In this study, it was determined that it was because the behavior of particles and the load transferred to the specimen were not well simulated, which remains a problem for future research. As a result, it was confirmed that it is possible to compute a worn shape similar to the measured shape of experiments. Thereafter, the change in the contact load predicted by simulation is discussed in terms of wear shape and cross-sectional area loss ratio.

Two- and three-dimensional simulations of flow and heat transfer around rectangular cylinders

This numerical study investigates the forced convection heat transfer from and flow topology around isothermal rectangular cylinders. The effects of various cross-sectional aspect ratios (AR = 0.25–4), Reynolds numbers (Re = 30–200), and Prandtl numbers (Pr = 0.7, 5) are examined on the results. Two or three-dimensional simulations are conducted depending on the Re and AR employed. The results show that the near primary vortices (Kármán wake) undergo a downstream transition to the two-layered vortices, followed by a transition from the two-layered vortices to the secondary vortices for AR ≤ 1. For smaller aspect ratios, the prevailing of the secondary vortices is further accelerated, i.e., they emerge at a lower Re and a shorter downstream distance from the cylinder. Three types of secondary vortices distinguished based on their shape, strength, and generation mechanism were observed. A geometric criterion (spacing ratio) for the onset of evolution of the two-layer structure is proposed for each AR. It is observed that the sensitiveness of the Nusselt number to AR and Re can be ascribed to the change in the scenarios of the flow separation and reattachment (flow regimes), vortex strength, and wake-recirculation size (Lr). The Nusselt number grows with increasing Re and Pr but diminishes with AR. The relationship between the average Nusselt number and Lr is direct in the steady flow, while they are inversely linked in the two- and three-dimensional unsteady flow. Reducing AR from 4 to 0.25, depending on Re and Pr, leads to a 90%–170% enhancement in the Nusselt number, whereas increasing AR amplifies the total heat transfer due to an enlargement in the heat transfer surfaces. The second law of thermodynamics analysis reveals that cylinders with smaller AR generate lower entropy (destroy lower exergy); therefore, they are more efficient.

Flow distribution in the air cooler of HTGR passive cavity cooling system

Passive Cavity Cooling System (PCCS) is an important safety related system for High Temperature Gas-cooled Reactor (HTGR). Air cooler is one of the key components of this system. The non-uniform flow distribution is a common issue encountered in similar Parallel Tube Heat Exchanger (PTHX). Improving flow uniformity is favorable for both thermal hydraulic performance and structure safety. In this work, the flow distribution characteristics of a compact parallel tube air cooler with U-type header arrangement are theoretically and numerically investigated. First, a theoretical discrete model is proposed for flow distribution in PTHX. It reveals that the static pressure distributions in the headers are influenced by static pressure recovery, friction resistance and local pressure drop, which is directly related with flow uniformity. Then, the flow uniformity of Z-type and U-type header arrangements is numerically investigated and compared in detail. Moreover, the effects of thermal hydraulic parameter and geometrical parameter on flow uniformity are successively evaluated. Numerical results show that the flow uniformity of PCCS air cooler with U-type header arrangement is more excellent than that of Z-type header arrangement. Thermal hydraulic parameters, such as tube-side water temperature and mass flow rate, have little impact on flow uniformity. Nevertheless, the flow distribution characteristics are very sensitive to the geometrical parameters, including the insertion angle configuration, the flow area ratio of header to parallel heat transfer tubes (AR) and the cross-sectional area ratio of distribution header to collection header (DCR). Reasonable insertion angle configuration and decreasing AR can effectively enhance the flow uniformity of PCCS air cooler. For header match, it should be avoided that the distribution header diameter below the collection header diameter. As a result, the optimal structure design determined in this work is an air cooler with U-type header arrangement, where the inlet insertion angle is 0°, the outlet insertion angle is 180°, and the diameters of distribution header and collection header are both 120 mm. Its flow uniformity is improved by more than 50% compared with present design. This work reports a promising design modification, as the potential structure optimization for HTGR PCCS air cooler.

A multi-institutional study of association of sonographic characteristics with cervical lymph node metastasis in unifocal papillary thyroid carcinoma.

ObjectivePapillary thyroid carcinoma (PTC) is the most common pathological type of thyroid carcinoma, and is prone to cervical lymph node metastases (CLNM). We aim to evaluate the association between sonographic characteristics of PTC and CLNM before the initial surgery.MethodsClinical information as well as ultrasonographic measurements and characteristics for 2376 patients from three hospitals were acquired in this retrospective cohort study. Univariate and multivariate logistic analysis were performed to predict CLNM in unifocal PTC patients. Receiver operating characteristic (ROC) curve was created to evaluate diagnostic performance.ResultsUnivariate analysis showed that gender, age, maximum tumor diameter and volume, cross-sectional and longitudinal aspect ratio, location, echogenicity, margin, and echogenic foci were independently associated with CLNM metastatic status (P < 0.05). Multivariate logistic analysis showed that gender, age, maximum tumor diameter and volume, cross-sectional aspect ratio (CSAR), location, echogenicity, margin, and echogenic foci were independent correlative factors; CSAR showed a significant difference for PTC2 to predict CLNM. The area under the curve (AUC) of the maximum tumor diameter, tumor volume, margin, and echogenic foci was 0.70, 0.69, 0.65, and 0.70, respectively. The multiple-variable linear regression model was constructed with an AUC of 0.77, a specificity of 73.4%, and a sensitivity of 72.3%. Kruskal-Wallis analysis for positive subgroups, maximum tumor diameter and volume, cross-sectional and longitudinal aspect ratio, margin, and echogenic foci showed statistical significance (P < 0.05).ConclusionsYounger age (< 55 years), male, larger tumor, and echogenic foci were high risk factors for CLNM in patients with unifocal PTC. CSAR had a more effective predictive value for CLNM in patients with larger thyroid tumors. A larger tumor with irregular and punctate echogenic foci was also more prone to the lateral neck, and both central and lateral neck metastasis.

Actuation performance of machined helical springs from NiTi shape memory alloy

Machined helical springs were designed and fabricated from NiTi shape memory alloy tube stock by cutting helical slots to make the coils, which provided them with high design flexibility and actuation potential. The springs were then subjected to isothermal tensile testing at temperatures of 20°C and 80°C, the experimental data showed that they could generate more than 50% actuation stroke at the applied force of 300 N. A material model was introduced to describe the thermally-induced actuation behavior of the machined NiTi spring. Finite element simulation of the springs was carried out to investigate the effects of geometries and applied loads on the actuation performance. With increasing applied load, the actuation stroke and transformation temperature increased as well, indicating more actuation potential at high loads. The actuation stroke was positively correlated to the outer diameter and the cross-sectional aspect ratio, negatively correlated to the cross-sectional area, and independent of the coil pitch. A variable-sweep wing actuated by two antagonistic machined springs was designed and numerically analyzed, the actuator could generate a steady cyclic motion up to 40 mm and allowed the swept-back angle of the wings to be continuously varied from zero to 90 degrees.

Amniotic Membrane Scaffolds Support Organized Muscle Regeneration in A Murine Volumetric Muscle Defect Model.

Background:Current treatment for volumetric muscle loss is limited to muscle transfer or acellular collagen scaffold (ACS) therapies that are associated with donor site morbidity and nonfunctional fibrosis, respectively. The aim of this study is to assess the utility of amniotic membrane scaffold (AMS) for volumetric muscle loss treatment.Methods:Murine quadriceps defects were created and randomized to three groups (n = 5/group): untreated controls, ACS, and AMS. In vivo muscle regeneration volume was quantified by MRI and microcomputed tomography. Muscle explants were analyzed using standard histology and whole-mount immunofluorescence at 8 weeks.Results:The cross-sectional muscle regeneration ratio was 0.64 ± 0.3 for AMS, 0.48 ± 0.07 for ACS, and 0.4 0 ± 0.03 for controls as assessed by MRI (P = 0.09) and 0.61 ± 0.28 for AMS, 0.50 ± 0.06 for ACS, and 0.43 ± 0.04 for controls as assessed by microcomputed tomography (P = 0.2). Histologically, AMS demonstrated significantly higher cellular density (900 ± 2 70 nuclei/high powered field) than ACS (210 ± 36) and control (130 ± 4) groups (P = 0.05). Immunofluorescence for laminin (AMS 623 ± 11 versus ACS 339 ± 3 versus control 115 ± 7; P < 0.01) and myosin heavy chain (AMS 509 ± 7 versus ACS 288 ± 5 versus control 84 ± 5; P = 0.03) indicated greater organized muscle fiber formation with AMS.Conclusion:AMS mediated muscle healing was characterized by increased cellular infiltration and organized muscle formation when compared with controls and ACS.

Experimental and numerical study on the axial compression performance of the prestressed sleeved members

The progressive collapse of large-span spatial structures can be triggered by the buckling of compression members. To further improve the stable load capacity of compression members, this study proposes a prestressed sleeved member by combining a prestressed stayed column system with a sleeved member. The experimental results show that the prestressed sleeved members possess a high load capacity, large secondary stiffness and moderate recovery performance, with the buckling modes of the members including first-order and second-order buckling. A nonlinear finite element (FE) model for the prestressed sleeved members is developed based on the experimental model. In addition, a series of parametric analyses are conducted to investigate the effects of the initial imperfection amplitude ratio, inner tube length to slenderness ratio, strand cross-sectional area ratio, inner and outer tube cross-sectional stiffness ratio and central support plate equivalent height ratio on the axial compression performance of the specimens. Furthermore, a simplified calculation model of the prestressed sleeved members is proposed for the case of second-order buckling, and theoretical calculation formulas are presented for three key points of the axial force–displacement curves of specimens. In contrast to the theoretical and FE results, the maximum errors of axial displacement and axial force do not exceed 15%. In addition, the steel strand tension, the contact force, and the lateral deflection of the middle section of the inner half-tube are highly consistent, which verifies the proposed relevant assumptions and theoretical calculation formulae.

Behavior of square and rectangular concrete-filled steel tube (CFST) columns with horizontal reinforcing bars under eccentric compression

A series of eccentric compression tests on square CFST columns with horizontal reinforcing bars were conducted, focusing on the effects of eccentricity ratio, different types of horizontal reinforcing bars (binding bars and inclined tension bars), and bar spacing. In addition, the results of a previous study on rectangular CFST columns with binding bars were also included for comparison, aiming to investigate the strengthening performance of installing horizontal reinforcing bars for both rectangular and square CFST columns. It is found that the restraining effect provided by the reinforcing bars could not only delay and restrain steel tube buckling, but also enhance the ultimate strength and lead to a more ductile post-peak descending branch for the load-axial strain, load-lateral strain, and moment–curvature curves. For square CFST columns under eccentric compression, installing binding bars which led to a 30%–40% enhancement in ultimate strength was more efficient than installing inclined tension bars of the same reinforcement ratio which only had less than 20% enhancement. Meanwhile, the ductility of the columns was significantly improved by reinforcing bars. Furthermore, the columns with binding bars had better ductility than those with inclined tension bars. Generally, binding bars can more efficiently improve the eccentric load behavior of CFST columns than inclined tension bars. For rectangular CFST columns under eccentric compression, reducing the spacing of binding bars can slightly increase the ultimate strength by around 7% while the ductility of the columns can be increased significantly by reducing the bar spacing. In addition, increasing the cross-sectional aspect ratio of the rectangular CFST columns would offset the restraining effect of the binding bars. In the end, a discussion was provided for a design code assessment against the test results.

Predictive Factors for Late-Onset Neurological Deficits in Patients with Posttuberculous Thoracic Kyphosis.

Background Patients with severe posttuberculous (TB) kyphosis might suffer from late-onset neurological deficits, and surgical correction may improve neurological function. However, there is a lack of predictive factors for neurological function in these patients. Objective This study was aimed at identifying the risk factors for late-onset neurological deficits in spinal TB patients at initial and final assessments. Methods Seventy-eight patients with severe kyphosis caused by old thoracic tuberculosis were retrospectively analyzed. Patients with active spinal TB and other spinal diseases were excluded from the analysis. The kyphosis Cobb angle, sagittal deformity angular ratio (S-DAR), and level of apex were measured and calculated on X-ray. The spinal cord cross-sectional area ratio (CSAR), spinal cord sagittal diameter ratio (SDR), and spinal cord angle (SCA) were measured on preoperative T2-weighted magnetic resonance imaging (MRI). According to the American Spinal Injury Association (ASIA) Impairment Scale (AIS) at the time of admission, the patients were divided into the symptomatic group (N = 60 patients, AIS grades A to D) and the asymptomatic group (N = 18 patients, AIS grade E). All of the symptomatic patients underwent surgery, and the patients from both groups had at least 2 years of follow-up. Relationships among the radiological parameters and initial and final AIS grades were evaluated via univariate and multivariate analyses. Results The mean duration of kyphotic deformity was 37.4 years in the symptomatic group. There were no significant differences between the two groups in terms of CSAR, kyphosis Cobb angle, S-DAR, level of apex, or the segments that were involved. Patients from the symptomatic group exhibited significantly greater SDR and smaller SCA than those from the asymptomatic group (p < 0.01 and p < 0.01, respectively). The multivariate logistic regression identified SDR and SCA as independent factors influencing the likelihood of spinal cord injury at the initial and final assessments. Conclusions Severe posttuberculous kyphosis may lead to significant neurological symptoms many years following the initial treatment. The predictive factors for late-onset neurological deficits include larger SDR and smaller SCA.