Search

Solar filament eruptions often show complex and dramatic geometric deformation that is highly relevant to the underlying physical mechanism triggering the eruptions. It has been well known that the writhe of filament axes is a key parameter characterizing its global geometric deformation, but a quantitative investigation of the development of writhe during its eruption is still lacking. Here we introduce the Writhe Application Toolkit (WAT) which can be used to characterize accurately the topology of filament axes. This characterization is achieved based on the reconstruction and writhe number computation of three-dimensional paths of the filament axes from dual-perspective observations. We apply this toolkit to four dextral filaments located in the northern hemisphere with a counterclockwise (CCW) rotation during their eruptions. Initially, all these filaments possess a small writhe number (=<0.20) indicating a weak helical deformation of the axes. As the CCW rotation kicks in, their writhe numbers begin to decrease and reach large negative values. Combined with the extended C\u{a}lug\u{a}reanu theorem, the absolute value of twist is deduced to decrease during the rotation. Such a quantitative analysis strongly indicates a consequence of the conversion of twist into writhe for the studied events.

Solar eruptions often show the rotation of filaments, which is a manifestation of the rotation of erupting magnetic flux rope (MFR). Such a rotation of MFR can be induced by either the torque exerted by a background shear-field component (which is an external cause) or the relaxation of the magnetic twist of the MFR (an internal cause). For a given chirality of the erupting field, both the external and internal drivers cause the same rotation direction. Therefore, it remains elusive from direct observations which mechanism yields the dominant contribution to the rotation. In this paper, we exploit a full MHD simulation of solar eruption by tether-cutting magnetic reconnection to study the mechanism of MFR rotation. In the simulation, the MFR's height-rotation profile suggests that the force by the external shear-field component is a dominant contributor to the rotation. Furthermore, the torque analysis confirms that it is also the only factor in driving the counterclockwise rotation. On the contrary, the Lorentz torque inside the MFR makes a negative effect on this counterclockwise rotation.

Artificial neural networks have realized incredible successes at image recognition, but the underlying mechanism of visual space representation remains a huge mystery. Grid cells (2014 Nobel Prize) in the entorhinal cortex support a periodic representation as a metric for coding space. Here, we develop a self-supervised convolutional neural network to perform visual space location, leading to the emergence of single-slit diffraction and double-slit interference patterns of waves. Our discoveries reveal the nature of CNN encoding visual space to a certain extent. CNN is no longer a black box in terms of visual spatial encoding, it is interpretable. Our findings indicate that the periodicity property of waves provides a space metric, suggesting a general role of spatial coordinate frame in artificial neural networks.

Lei Wang, Kai Zhang, Yongqiang Hao, Ming Liu, Wen WuDepartment of Orthopaedics, Shanghai Key Laboratory of Orthopaedic Implants, Shanghai Ninth People’s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200011, People’s Republic of ChinaAbstract: The porous surface of a polyetheretherketone (PK)–nanoporous lithium-doped magnesium silicate (NLS) blend (PKNLS) was fabricated on a PK surface by layer-by-layer pressuring, sintering, and salt-leaching. As controls, porous surfaces of a PK/lithium-doped magnesium silicate blend (PKLS) and PK were fabricated using the same method. The results revealed that porosity, water absorption, and protein absorption of the porous surface of PKNLS containing macropores and nanopores were obviously enhanced compared to PKLS and PK containing macropores without nanopores. In addition, PKNLS, with both macroporostiy and nanoporosity, displayed the highest ability of apatite mineralization in simulated body liquid, indicating excellent bioactivity. In vitro responses (including adhesion, proliferation, and differentiation) of MC3T3E1 cells to PKNLS were significantly enhanced compared to PKLS and PK. In vivo implantation results showed that new bone grew into the macroporous surface of PKNLS, and the amount of new bone for PKNLS was the highest. In short, PKNLS integration with PK significantly promoted cells/bone-tissue responses and exhibited excellent osteogenesis in vivo, which might have great potential for bone repair.Keywords: polyetheretherketone, nanoporous lithium doped magnesium silicate, porously bioactive surface, cells responses, osteogenesis

Lei Wang, Kai Zhang, Yongqiang Hao, Ming Liu, Wen WuDepartment of Orthopaedics, Shanghai Key Laboratory of Orthopaedic Implants, Shanghai Ninth People’s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200011, People’s Republic of ChinaAbstract: The porous surface of a polyetheretherketone (PK)–nanoporous lithium-doped magnesium silicate (NLS) blend (PKNLS) was fabricated on a PK surface by layer-by-layer pressuring, sintering, and salt-leaching. As controls, porous surfaces of a PK/lithium-doped magnesium silicate blend (PKLS) and PK were fabricated using the same method. The results revealed that porosity, water absorption, and protein absorption of the porous surface of PKNLS containing macropores and nanopores were obviously enhanced compared to PKLS and PK containing macropores without nanopores. In addition, PKNLS, with both macroporostiy and nanoporosity, displayed the highest ability of apatite mineralization in simulated body liquid, indicating excellent bioactivity. In vitro responses (including adhesion, proliferation, and differentiation) of MC3T3E1 cells to PKNLS were significantly enhanced compared to PKLS and PK. In vivo implantation results showed that new bone grew into the macroporous surface of PKNLS, and the amount of new bone for PKNLS was the highest. In short, PKNLS integration with PK significantly promoted cells/bone-tissue responses and exhibited excellent osteogenesis in vivo, which might have great potential for bone repair.Keywords: polyetheretherketone, nanoporous lithium doped magnesium silicate, porously bioactive surface, cells responses, osteogenesis

Lei Wang,1,* Guoyuan Li,1,* Ling Ren,2,* Xiangdong Kong,1 Yugang Wang,1 Xiuguo Han,1 Wenbo Jiang,3 Kerong Dai,1 Ke Yang,2 Yongqiang Hao11Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, 2Special Materials and Device Research Department, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 3Medical 3D Printing Innovation Research Center, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: Treatment for fractures requires internal fixation devices, which are mainly produced from stainless steel or titanium alloy without biological functions. Therefore, we developed a novel nano-copper-bearing stainless steel with nano-sized copper-precipitation (317L-Cu SS). Based on previous studies, this work explores the effect of 317L-Cu SS on fracture healing; that is, proliferation, osteogenic differentiation, osteogenesis-related gene expression, and lysyl oxidase activity of human bone mesenchymal stem cells were detected in vitro. Sprague–Dawley rats were used to build an animal fracture model, and fracture healing and callus evolution were investigated by radiology (X-ray and micro-CT), histology (H&E, Masson, and safranin O/fast green staining), and histomorphometry. Further, the Cu2+ content and Runx2 level in the callus were determined, and local mechanical test of the fracture was performed to assess the healing quality. Our results revealed that 317L-Cu SS did not affect the proliferation of human bone mesenchymal stem cells, but promoted osteogenic differentiation and the expression of osteogenesis-related genes. In addition, 317L-Cu SS upregulated the lysyl oxidase activity. The X-ray and micro-CT results showed that the callus evolution efficiency and fracture he

Lei Wang,1,* Guoyuan Li,1,* Ling Ren,2,* Xiangdong Kong,1 Yugang Wang,1 Xiuguo Han,1 Wenbo Jiang,3 Kerong Dai,1 Ke Yang,2 Yongqiang Hao11Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, 2Special Materials and Device Research Department, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 3Medical 3D Printing Innovation Research Center, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: Treatment for fractures requires internal fixation devices, which are mainly produced from stainless steel or titanium alloy without biological functions. Therefore, we developed a novel nano-copper-bearing stainless steel with nano-sized copper-precipitation (317L-Cu SS). Based on previous studies, this work explores the effect of 317L-Cu SS on fracture healing; that is, proliferation, osteogenic differentiation, osteogenesis-related gene expression, and lysyl oxidase activity of human bone mesenchymal stem cells were detected in vitro. Sprague–Dawley rats were used to build an animal fracture model, and fracture healing and callus evolution were investigated by radiology (X-ray and micro-CT), histology (H&E, Masson, and safranin O/fast green staining), and histomorphometry. Further, the Cu2+ content and Runx2 level in the callus were determined, and local mechanical test of the fracture was performed to assess the healing quality. Our results revealed that 317L-Cu SS did not affect the proliferation of human bone mesenchymal stem cells, but promoted osteogenic differentiation and the expression of osteogenesis-related genes. In addition, 317L-Cu SS upregulated the lysyl oxidase activity. The X-ray and micro-CT results showed that the callus evolution efficiency and fracture he

Lei Wang,1,* Ling Ren,2,* Tingting Tang,1 Kerong Dai,1 Ke Yang,2 Yongqiang Hao1 1Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, People’s Republic of China; 2Institute of Metal Research, Chinese Academy of Sciences, Shenyang, People’s Republic of China *These authors contributed equally to this work Abstract: Foreign body reaction induced by biomaterials is a serious problem in clinical applications. Although 317L-Cu stainless steel (317L-Cu SS) is a new type of implant material with antibacterial ability and osteogenic property, the foreign body reaction level still needs to be assessed due to its Cu2+ releasing property. For this purpose, two macrophage cell lines were selected to detect cellular proliferation, apoptosis, mobility, and the secretions of inflammatory cytokines with the influence of 317L-Cu SS. Our results indicated that 317L-Cu SS had no obvious effect on the proliferation and apoptosis of macrophages; however, it significantly increased cellular migration and TNF-α secretion. Then, C57 mice were used to assess foreign body reaction induced by 317L-Cu SS. We observed significantly enhanced recruitment of inflammatory cells (primarily macrophages) with increased TNF-α secretion and apoptosis level in tissues around the materials in the early stage of implantation. With tissue healing, both inflammation and apoptosis significantly decreased. Further, we discovered that NF-κB pathway and Caspase 3 played important roles in 317L-Cu SS induced inflammation and apoptosis. We concluded that 317L-Cu SS could briefly promote the inflammation and apoptosis of surrounding tissues by regulating the activity of NF-κB pathway and Caspase 3. All these discoveries demonstrated that 317L-Cu SS has a great potential for clinical application. Keywords: nano-cop

Lei Wang,1,* Ling Ren,2,* Tingting Tang,1 Kerong Dai,1 Ke Yang,2 Yongqiang Hao1 1Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, People’s Republic of China; 2Institute of Metal Research, Chinese Academy of Sciences, Shenyang, People’s Republic of China *These authors contributed equally to this work Abstract: Foreign body reaction induced by biomaterials is a serious problem in clinical applications. Although 317L-Cu stainless steel (317L-Cu SS) is a new type of implant material with antibacterial ability and osteogenic property, the foreign body reaction level still needs to be assessed due to its Cu2+ releasing property. For this purpose, two macrophage cell lines were selected to detect cellular proliferation, apoptosis, mobility, and the secretions of inflammatory cytokines with the influence of 317L-Cu SS. Our results indicated that 317L-Cu SS had no obvious effect on the proliferation and apoptosis of macrophages; however, it significantly increased cellular migration and TNF-α secretion. Then, C57 mice were used to assess foreign body reaction induced by 317L-Cu SS. We observed significantly enhanced recruitment of inflammatory cells (primarily macrophages) with increased TNF-α secretion and apoptosis level in tissues around the materials in the early stage of implantation. With tissue healing, both inflammation and apoptosis significantly decreased. Further, we discovered that NF-κB pathway and Caspase 3 played important roles in 317L-Cu SS induced inflammation and apoptosis. We concluded that 317L-Cu SS could briefly promote the inflammation and apoptosis of surrounding tissues by regulating the activity of NF-κB pathway and Caspase 3. All these discoveries demonstrated that 317L-Cu SS has a great potential for clinical application. Keywords: nano-cop