Polyetheretherketone implants with hierarchical porous structure for boosted osseointegration

Zhiyong Chen,Yu Chen,Yang Wang,JiaJia Deng,Xin Wang,Qingqing Wang,Yuehua Liu,Jiandong Ding,Lin Yu 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Background Good osseointegration is the key to the long-term stability of bone implants. Thermoplastic polyetheretherketone (PEEK) has been widely used in orthopedics; however, its inherent biological inertia causes fibrous tissue to wrap its surface, which leads to poor osseointegration and thus greatly limits its clinical applications. Methods Herein, we developed a facile yet effective surface modification strategy. A commonly used sulfonation coupled with “cold pressing” treatment in the presence of porogenic agent formed a three-dimensional hierarchical porous structure on PEEK surface. Subsequently, the effects of porous surface on the in vitro adhesion, proliferation and differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) were evaluated. Finally, the osteoinduction and osseointegration of surface-porous PEEK implant were examined in the rat distal femoral defect model. Results In vitro results showed that the surface modification did not significantly affect the mechanical performance and cytocompatibility of PEEK substance, and the porous structure on the modified PEEK substrate provided space for cellular ingrowth and enhanced osteogenic differentiation and mineralization of BMSCs. In vivo tests demonstrated that the surface-porous PEEK implant could effectively promote new bone formation and had higher bone-implant contact rate, thereby achieving good bone integration with the surrounding host bone. In addition, this modification technique was also successfully demonstrated on a medical PEEK interbody fusion cage. Conclusion The present study indicates that topological morphology plays a pivotal role in determining implant osseointegration and this facile and effective modification strategy developed by us is expected to achieve practical applications quickly.

Vagal Transient Receptor Potential Ankyrin 1 Mediates Stress-exacerbated Visceral Mechanonociception After Antral Cold Exposure

Xin Chen,Qingqing Luo,Xiujuan Yan,Wenting Li,Shengliang Chen 대한소화기 기능성질환∙운동학회 2019 Journal of Neurogastroenterology and Motility (JNM Vol.25 No.3

Background/AimsAbdominal pain can be evoked or exacerbated after gastrointestinal cold stimulation in some patients with diarrhea-predominantirritable bowel syndrome (IBS-D), indicating a low temperature-induced sensitization of visceral perception. We investigated the roleof vagal transient receptor potential ankyrin 1 (TRPA1, a cold-sensing ion channel) in cold-aggravated visceral mechanonociception ina stress-induced IBS animal model. MethodsTRPA1 expression was examined in antral biopsies of healthy controls and IBS-D patients. Abdominal symptoms were assessed beforeand after warm or cold water intake. The visceromotor response (VMR) to colorectal distention (CRD) following intra-antral infusionof cold saline was measured in animals undergoing sham or chronic water avoidance stress. TRPA1 expression, extracellular signalregulatedprotein kinase 1/2 (ERK1/2) phosphorylation, and neuronal calcium influx in vagal afferents were assessed. ResultsCompared to healthy controls, IBS-D patients displayed elevated antral TRPA1 expression, which was associated with symptom scoresafter cold (4°C) water intake. Intra-antral infusion of cold saline increased VMR to CRD in naive rats, an effect dependent on vagalafferents. In stressed rats, this effect was greatly enhanced. Functional blockade and gene deletion of TRPA1 abolished the cold effecton visceral nociception. TRPA1 expression in vagal (but not spinal) afferents increased after stress. Moreover, the cold-induced, TRPA1-dependent ERK1/2 activation and calcium influx in nodose neurons were more robust in stressed rats. ConclusionsStress-exaggerated visceral mechanonociception after antral cold exposure may involve up-regulation of TRPA1 expression andfunction on vagal afferents. Our findings reveal a novel mechanism for abnormal gastrointestinal cold sensing in IBS.

Experimental Study of the Shear Capacity of Steel Beam-to-L-CFST Column Connections

Qingqing Xiong,Wang Zhang,Zhi-Hua Chen,Yansheng Du,Ting Zhou 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3

This paper aims to investigate the shear performance of a new and innovative type of vertical stiff ener connection between steel beams and L-shaped columns composed of concrete-fi lled steel tubes connected by transverse and vertical steel plates (L-CFST columns) in high-rise residential buildings. Quasi-static cyclic loading tests were performed on fi ve full-scale specimens to investigate the panel zone behaviours. Based on the experimental results, the hysteretic responses, skeleton curves of the shear force–deformation, ductility, stiff ness degradation, energy dissipation and strain are discussed. The variables studied in these experiments include the joint type, axial compression ratio, cross-sectional area and width-to-thickness ratio of the vertical stiff ener, and presence of concrete. The results indicate that the cross-sectional area of the vertical stiff eners plays a critical role in the performance of the panel zone. Two types of failure modes were observed outside the panel zone: fracturing of the vertical stiff eners and fracturing of the beam fl ange connecting plate. Shear deformation of the panel zone was obvious in the exterior joint specimens, and the corresponding maximum shear deformation reached 0.05 rad. Furthermore, the scopes of the panel zone in the corner and exterior joint specimens were determined by the strain distribution.

Epstein–Barr virus-positive T/NK-cell lymphoproliferative disorders

Qingqing Cai,Kailin Chen,Ken H Young 생화학분자생물학회 2015 Experimental and molecular medicine Vol.47 No.-

Epstein–Barr virus, a ubiquitous human herpesvirus, can induce both lytic and latent infections that result in a variety of human diseases, including lymphoproliferative disorders. The oncogenic potential of Epstein–Barr virus is related to its ability to infect and transform B lymphocytes into continuously proliferating lymphoblastoid cells. However, Epstein–Barr virus has also beenimplicated in the development of T/natural killer cell lymphoproliferative diseases. Epstein–Barr virus encodes a series of products that mimic several growth, transcription and anti-apoptotic factors, thus usurping control of pathways that regulate diverse homeostatic cellular functions and the microenvironment. However, the exact mechanism by which Epstein–Barr virus promotes oncogenesis and inflammatory lesion development remains unclear. Epstein–Barr virus-associated T/natural killer cell lymphoproliferative diseases often have overlapping clinical symptoms as well as histologic and immunophenotypic features because both lymphoid cell types derive from a common precursor. Accurate classification of Epstein–Barr virus-associated T/natural killer cell lymphoproliferative diseases is a prerequisite for appropriate clinical management. Currently, the treatment ofmost T/natural killer cell lymphoproliferative diseases is less than satisfactory. Novel and targeted therapies are strongly required to satisfy clinical demands. This review describes our current knowledge of the genetics, oncogenesis, biology, diagnosis and treatment of Epstein–Barr virus-associated T/natural killer cell lymphoproliferative diseases.

Preparation and Performance of Aluminosilicate Fibrous Porous Ceramics Via Vacuum Suction Filtration

Qingqing Wang,Shaofeng Zhu,Zhenfan Chen,Tong Zhang 한국재료학회 2024 한국재료학회지 Vol.34 No.1

This study successfully prepared high-porosity aluminosilicate fibrous porous ceramics through vacuum suction filtration using aluminosilicate fiber as the primary raw material and glass powder as binder, with the appropriate incorporation of glass fiber. The effects of the composition of raw materials and sintering process on the structure and properties of the material were studied. The results show that when the content of glass powder reached 20 wt% and the samples were sintered at the temperature of 1,000 °C, strong bonds were formed between the binder phase and fibers, resulting in a compressive strength of 0.63 MPa. When the sintering temperatures were increased from 1,000 °C to 1,200, the open porosity of the samples decreased from 89.08 % to 82.38 %, while the linear shrinkage increased from 1.13 % to 10.17 %. Meanwhile, during the sintering process, a large amount of cristobalite and mullite were precipitated from the aluminosilicate fibers, which reduced the performance of the aluminosilicate fibers and hindered the comprehensive improvement in sample performance. Based on these conditions, after adding 30 wt% glass fiber and being sintered at 1,000 °C, the sample exhibited higher compressive strength (1.34 MPa), higher open porosity (89.13 %), and lower linear shrinkage (5.26 %). The aluminosilicate fibrous porous ceramic samples exhibited excellent permeability performance due to their high porosity and interconnected three-dimensional pore structures. When the samples were filtered at a flow rate of 150 mL/min, the measured pressure drop and permeability were 0.56 KPa and 0.77 × 10-6 m2 respectively.

Proteome analysis reveals global response to deletion of mrflbA in Monascus ruber

Qingqing Yan,Zhouwei Zhang,Yishan Yang,Fusheng Chen,Yanchun Shao 한국미생물학회 2018 The journal of microbiology Vol.56 No.4

Monascus spp. are commonly used for a wide variety of applications in the food and pharmaceutical industries. In previous studies, the knock-out of mrflbA (a putative regulator of the G protein α subunit) in M. ruber led to autolysis of the mycelia, decreased pigmentation and lowered mycotoxin production. Therefore, we aimed to obtain a comprehensive overview of the underlying mechanism of mrflbA deletion at the proteome level. A two-dimensional gel electrophoresis analysis of mycelial proteins indicated that the abundance of 178 proteins was altered in the ΔmrflbA strain, 33 of which were identified with high confidence. The identified proteins are involved in a range of activities, including carbohydrate and amino acid metabolism, hyphal development and the oxidative stress response, protein modification, and the regulation of cell signaling. Consistent with these findings, the activity of antioxidative enzymes and chitinase was elevated in the supernatant of the ΔmrflbA strain. Furthermore, deletion of mrflbA resulted in the transcriptional reduction of secondary metabolites (pigment and mycotoxin). In short, the mutant phenotypes induced by the deletion of mrflbA were consistent with changes in the expression levels of associated proteins, providing direct evidence of the regulatory functions mediated by mrflbA in M. ruber.

Do Analysts’ Cross-year Revisions Contain Information about Audit Adjustment? Evidence from the Chinese Capital Market

Qingqing Liu,Songsheng Chen,Zhili Tian 한국증권학회 2021 Asia-Pacific Journal of Financial Studies Vol.50 No.4

This study tests the information content of changes in analysts’ earnings forecasts. Using audit adjustment data from China, this study investigates whether changes in analysts’ crossyear forecast revisions reflect audit information. The results show that the cross-year revision of analysts’ earnings per share forecasts is positively related to the magnitude of audit adjustment, which may be mainly due to analysts’ communication with management. Furthermore, analysts who display higher forecast frequency, who issue their last forecast closer to the day the annual report is announced, or who show better forecast performance reflect a greater amount of audit information in their cross-year forecast revisions.

Study on the progressive collapse resistance of CP-FBSP connections in LCFST frame structe

Qingqing Xiong,Wenbo Wu,Wang Zhang,Zhihua Chen,Hongbo Liu,Tiancheng Su 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.3

When the vertical load-bearing members in high-rise structures fail locally, the beam-column joints play an important role in the redistribution of the internal forces. In this paper, a static laboratory test of three full-scale flush flange beam-reinforced connections with side and cover plates (CP-FBSP connection) with double half-span steel beams and single Lshaped columns composed of concrete-filled steel tubes (L-CFST columns) was conducted. The influence of the side plate width and cover plate thickness on the progressive collapse resistance of the substructure was thoroughly analyzed. The failure mode, vertical force-displacement curves, strain variation, reaction force of the pin support and development of internal force in the section with the assumed plastic hinge were discussed. Then, through the verified finite element model, the corresponding analyses of the thickness and length of the side plates, the connecting length between the steel beam flange and cover plate, and the vertical-force eccentricity were carried out. The results show that the failure of all the specimens occurred through the cracking of the beam flange or the cover plate, and the beam chord rotations measured by the test were all greater than 0.085 rad. Increasing the length, thickness and width of the side plates slightly reduced the progressive collapse resistance of the substructures. The vertical-force eccentricity along the beam length reduced the progressive collapse resistance of the substructure. An increase in the connecting length between the beam flange and cover plate can significantly improve the progressive collapse resistance of substructures.

Potential Difference of Cyclic Polarization Curve of an Aircraft Al Alloy: ∆E (E_sec,corr - E_corr)

Sun, Qingqing,Chen, Kanghua The Korean Electrochemical Society 2020 Journal of electrochemical science and technology Vol.11 No.2

This paper presents a hypothesis and its experimental validation that ∆E (E_sec,corr - E_corr) of cyclic polarization curve of an Al-Zn-Mg-Cu alloy decreases firstly and then increases with the increasing of corrosion rate or corroded fraction F_corr of alloy surface. The minimum value of ∆E is obtained when F_corr ≈ 50%. In addition, a proportional relationship between ∆E and |50% - F_corr| was found. This non-monotonic relation between ∆E and extent of localized corrosion indicates that additional attention should be paid on using ∆E to assess localized corrosion behaviour of Al-Zn-Mg-Cu alloys.

Distributed Model Predictive Control of Iron Precipitation Process by Goethite Based on Dual Iterative Method

Ning Chen,Jiayang Dai,Xiaojun Zhou,Qingqing Yang,Weihua Gui 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.5

Iron precipitation is a key process in zinc hydrometallurgy. The process consists of a series of continuousreactors arranged in descending order, overflowing zinc leach solution from one reactor to the next. In this paper,according to the law of mass conservation and the reaction kinetics, a continuously stirred tank reactor model ofa single reactor is first established. Then, a distributed model of cascade reactors is built with coupled controlbased on the single reactor model, considering the unreacted oxygen in leaching solution. Secondly, four reactorsin the iron precipitation process are considered as four subsystems, the optimization control problem of the processis solved by a distributed model predictive control strategy. Moreover, the control information feedback betweensuccessive subsystems is used to solve the optimization problem of each subsystem, because of the existing controlcoupling in their optimization objective function of pre and post subsystems. Next, considering the intractability ofthe optimization problem for subsystems with various constraints, a distributed dual iterative algorithm is proposedto simplify the calculation. With the consideration of its cascade structure and control couplings, the proposedalgorithm iteratively solves the primal problem and the dual problem of each subsystem. The application case showsthat distributed model predictive control based on dual iteration algorithm can handle coupled control effectivelyand reduce the oxygen consumption.