To study the risk and control countermeasures of the TBM tunnel construction adjacent to the operational railway tunnel, based on the TBM tunnel project of Chongqing Rail Transit Line 5, this paper first evaluates the quality health degree of the operational tunnel lining (OTL) structure according to the on-site structural inspection. Then, the displacement, internal force, and proximity influence scope influenced by the metro TBM tunnel construction are studied using numerical simulation. Finally, the corresponding control countermeasures are proposed. The results show that: (1) The adjacent construction of the upper TBM tunnel will lead to the uplift deformation trend of the lower operational tunnel, and the uplift deformation of the vault is greater than that of the ballast bed. The influence scope is roughly a parallelogram, with the long axis parallel to the operational tunnel and the short axis parallel to the new TBM subway tunnel. (2) TBM tunnelling over the operational tunnel will cause the transformation of the mechanical mode of the OTL structure from the small eccentric compression mode to the large eccentric compression mode. The OTL structure between the left and right lines of TBM is unfavorable. (3) The longitudinal curve of the bending moment and axial force of the OTL fluctuates greatly within the influence range. The bending moment and axial force are reduced in operational tunnel construction joints. Based on field evaluation and numerical analysis, this paper puts forward some risk control countermeasures, such as TBM tunnelling parameters control, pea-gravel backfilling, backfill grouting, and bottom grouting, which can effectively solve the risk of the operational tunnel structure in the adjacent construction. This study has important reference value for risk control and safety assessment of tunnel in complex adjacent tunnel construction.
Vector-based cellular automata (CA) based on real land-parcel has become an important trend in current urban development simulation studies. Compared with raster-based and parcel-based CA models, vector CA models are difficult to be widely used because of their complex data structures and technical difficulties. The UrbanVCA, a brand-new vector CA-based urban development simulation framework was proposed in this study, which supports multiple machine-learning models. To measure the simulation accuracy better, this study also first proposes a vector-based landscape index (VecLI) model based on the real land-parcels. Using Shunde, Guangdong as the study area, the UrbanVCA simulates multiple types of urban land-use changes at the land-parcel level have achieved a high accuracy (FoM=0.243) and the landscape index similarity reaches 87.3%. The simulation results in 2030 show that the eco-protection scenario can promote urban agglomeration and reduce ecological aggression and loss of arable land by at least 60%. Besides, we have developed and released UrbanVCA software for urban planners and researchers.
Overactive bladder (OAB) is a common condition that affects a significant patient population. The N-methyl-D-aspartate receptor (NMDAR) has a role in developing bladder overactivity, pharmacological inhibition of which inhibits bladder overactivity. The common pathogenesis of OAB involves bladder smooth muscle (BSM) overactivity. In this study, a smooth muscle–specific NMDAR knockout ( SMNRKO ) mouse model was generated. The bladders from SMNRKO mice displayed normal size and weight with an intact bladder wall and well-arranged BSM bundles. Besides, SMNRKO mice had normal voiding patterns and urodynamics and BSM contractility, indicating that NMDAR in BSM was not essential for normal physiological bladder morphology and function. Unexpectedly, cyclophosphamide (CYP)-treated SMNRKO and wild-type (WT) mice had similar pathological changes in the bladder. Furthermore, SMNRKO mice displayed similar altered voiding patterns and urodynamic abnormalities and impaired BSM contractility compared with WT mice after CYP treatment. MK801 partially reversed the pathological bladder morphology and improved bladder dysfunction induced by CYP, but did not cause apparent differences between WT mice and SMNRKO mice, suggesting that NMDAR in BSM was not involved in pathological bladder morphology and function. Moreover, the direct instillation of NMDAR agonists or antagonists into the CYP-induced OAB did not affect bladder urodynamic function, indicating that NMDAR in BSM was not the pharmacotherapy target of MK801 for CYP-induced cystitis. The findings indicated that NMDAR in BSM was not essential for normal physiological or pathological bladder morphology and function, and MK801 improving pathological bladder function was not mediated by an action on NMDAR in BSM.
Large-scale cell culture for cell expansion in tissue engineering is currently a major focus of research. One method to achieve better cell amplification is to utilize microcarriers. In this study, different amounts of poly(γ-benzyl-l-glutamate) (PBLG) (from 11 wt% to 50 wt%) were grafted on mesoporous hydroxyapatite (MHA) by the in situ ring opening polymerization of γ-benzyl-l-glutamate N-carboxyanhydride (BLG-NCA), and biodegradable and biocompatible PBLG-g-MHA microcarriers were directly fabricated using the oil-in-water (O/W) solvent-evaporation technique for bone tissue engineering. The amount of grafted PBLG could be controlled by adjusting the feed ratio of MHA and BLG-NCA. The relationships between sphere morphology and graft amount or solution concentration were explored. Furthermore, cytological assays were performed to evaluate the biological properties of the PBLG-g-MHA microcarriers. For a solution concentration of 3% (w/v) and PBLG graft amounts of 33 wt% and 50 wt%, the microspheres could be harvested with optimal spherical shapes. In vitro cell culture revealed that the PBLG-g-MHA microspheres had favorable properties for cell proliferation and significantly enhanced the osteogenic differentiation of MC3T3-E1 cells and bone matrix formation.
Differently sized poly(lactic-co-glycolic) microspheres were efficiently prepared with electrified liquid jets and a phase separation technique for a wide range of applications. Higher polymer concentrations tended to form larger microcarriers. Polymer concentration can obviously affect bead or fiber formation resulting beads and fiber morphologies. As the voltage of electrostatic field and the needle size increased, the size of microcarriers decreased remarkably. The most suitable concentration of ethanol in the collecting solution might be lower than 55%. The resulting composite microcarriers have significantly narrow size distribution, controllable sizes, and high cell adhesion, growth, and osteodifferentiation abilities.
Abstract Polyetheretherketone (PEEK) is a promising bone and dental tissue engineering material with excellent mechanical properties and biocompatibility, but its biological inertness deficiency limits its clinical applications. In this study, poly(sodium p‐styrene sulfonate) (pNaSS) was grafted onto PEEK surface by ultraviolet (UV) induced polymerization to enhance its osteogenic activities. Attenuated total reflectance Fourier transformed Infrared (ATR‐FTIR) spectroscopy, scanning electron microscopy (SEM), and contact angle (CA) analysis were carried out to prove the success of grafting polymerization. Toluidine blue O (TBO) colorimetric assay was utilized to quantify the graft amounts of pNaSS. Results showed that the amounts of grafted pNaSS on the PEEK surface could be well‐controlled from 0.59 ± 0.07 mmol/cm 2 to 5.08 ± 0.20 mmol/cm 2 , through adjusting the UV irradiation time and monomer concentration. The hydrophilicity of PEEK surface was increased and the in vitro mineralization ability was promoted with the introduction of pNaSS. Besides, this surface modification method did not influence the intrinsic mechanical properties of PEEK. in vitro biological studies revealed that cell adhesion, proliferation, and osteogenic differentiation of MC3T3‐E1 cells were enhanced with the increase of graft amounts.
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