<strong>Rationale:</strong> The three-dimensional (3D) computer-made titanium mesh is widely used in the skull repair for those patients receiving decompression of the bone flap. It can restore normal anat...<strong>Rationale:</strong> The three-dimensional (3D) computer-made titanium mesh is widely used in the skull repair for those patients receiving decompression of the bone flap. It can restore normal anatomy to a greater extent and make a better appearance. <strong>Case Presentation: </strong>We reported two cases of patients admitted to our hospital who have experienced high scalp tension after skull repair. At first, these two patients underwent decompression of the bone flap, and the physical examination results showed a defect of skull. No neurological symptoms and signs were found. The 3D computed tomography (CT) reconstruction of skull was performed, and then the skull repair with 3D titanium mesh was conducted. But because of high scalp tension, they underwent a second operation, during which we re-trimmed and reduce the arc of the titanium mesh. The scalp incision of both patients healed well and no titanium mesh was exposed. Both patients have a good prognosis. <strong>Lessons:</strong> We highlight that the high tension of scalp due to overstretching after 3D titanium mesh repair for skull defect should be paid much attention to. Trimming and reducing the arc of titanium mesh is an effective treatment for this situation.展开更多
In order to study the behavior and interconnection of network devices,graphs structures are used to formulate the properties in terms of mathematical models.Mesh network(meshnet)is a LAN topology in which devices are ...In order to study the behavior and interconnection of network devices,graphs structures are used to formulate the properties in terms of mathematical models.Mesh network(meshnet)is a LAN topology in which devices are connected either directly or through some intermediate devices.These terminating and intermediate devices are considered as vertices of graph whereas wired or wireless connections among these devices are shown as edges of graph.Topological indices are used to reflect structural property of graphs in form of one real number.This structural invariant has revolutionized the field of chemistry to identify molecular descriptors of chemical compounds.These indices are extensively used for establishing relationships between the structure of nanotubes and their physico-chemical properties.In this paper a representation of sodium chloride(NaCl)is studied,because structure of NaCl is same as the Cartesian product of three paths of length exactly like a mesh network.In this way the general formula obtained in this paper can be used in chemistry as well as for any degree-based topological polynomials of three-dimensional mesh networks.展开更多
A series of three-dimensional ordered macroporous(3 DOM)W-TiO_(2)catalysts have been prepared through a facile colloidal crystal template method.The prepared materials characterized in detail exhibited enhanced cataly...A series of three-dimensional ordered macroporous(3 DOM)W-TiO_(2)catalysts have been prepared through a facile colloidal crystal template method.The prepared materials characterized in detail exhibited enhanced catalytic activity in aerobic oxidative desulfurization process.The experimental results indicated that the as-prepared materials possessed excellent 3 DOM structure,which is beneficial for the catalytic activity.The sample 3 DOM W-TiO_(2)-20 exhibited the highest activity in ODS process,and the sulfur removal can reach 98%in 6 h.Furthermore,the oxidative product was also analyzed in the reaction process.展开更多
Guided bone regeneration(GBR)is an effective and simple method for bone augmentation,which is often used to reconstruct the alveolar ridge when the bone defect occurs in the implant area.Titanium mesh has expanded the...Guided bone regeneration(GBR)is an effective and simple method for bone augmentation,which is often used to reconstruct the alveolar ridge when the bone defect occurs in the implant area.Titanium mesh has expanded the indications of GBR technology due to its excellent mechanical properties and biocompatibility,so that the GBR technology can be used to repair alveolar ridges with larger bone defects,and can obtain excellent and stable bone augmentation results.Currently,GBR with titanium mesh has various clinical applications,including different clinical procedures.Bone graft materials,titanium mesh covering methods,and titanium mesh fixing methods are also optional.Moreover,the research of GBR with titanium mesh has led to multifarious progresses in digitalization and material modification.This article reviews the properties of titanium mesh and the difference of titanium mesh with other barrier membranes;the current clinical application of titanium mesh in bone augmentation;common complications and management and prevention methods in the application of titanium mesh;and research progress of titanium mesh in digitization and material modification.Hoping to provide a reference for further improvement of titanium mesh in clinical application and related research of titanium mesh.展开更多
Guided bone regeneration(GBR)uses resorbable and non-resorbable membranes as biological barriers.This study compared the differences in hard tissue stability between GBR using evidence-based digital titanium mesh and ...Guided bone regeneration(GBR)uses resorbable and non-resorbable membranes as biological barriers.This study compared the differences in hard tissue stability between GBR using evidence-based digital titanium mesh and resorbable collagen membranes during implant placement.A total of 40 patients(65 implant sites)were enrolled and divided into two groups:resorbable membrane and digital titanium mesh groups.The alveolar bone was analyzed at two-and three-dimensional levels using conebeam computed tomography and by reconstructing and superimposing the hard tissues at four time points:preoperatively,postoperatively,before second-stage surgery,and 1 year after loading.The use of digital titanium mesh showed less alveolar bone resorption in vertical and horizontal directions two-dimensionally before the second-stage surgery and 1 year after loading.Regarding volumetric stability,the percentage of resorption after 6 months of healing with resorbable membrane coverage reached 37.5%.However,it was only 23.4%with titanium mesh.Although postoperative bone volume was greater at all labial sites with resorbable membrane than with digital titanium mesh,after substantial bone resorption within 1 year of loading,the labial bone thickness at the upper part of implants was thinner with resorbable membrane than with digital titanium mesh.Furthermore,digital titanium meshes made according to ideal bone arch contour reduced soft tissue irritation,and the exposure rate was only 10%.Therefore,although both resorbable membrane and digital titanium mesh in GBR were able to successfully reconstruct the bone defect,digital titanium meshes were better at maintaining the hard tissue volume in the osteogenic space.展开更多
Objective To evaluate the use of titanium mesh reconstruction after sternal tumor resection. Methods From January 2007 to January 2011, 14 patients with sternal tumors were admitted into Peking Union Medical Hospital....Objective To evaluate the use of titanium mesh reconstruction after sternal tumor resection. Methods From January 2007 to January 2011, 14 patients with sternal tumors were admitted into Peking Union Medical Hospital. The clinical characteristics, surgical resection, and technique of reconstruction were reviewed. Results Of the 14 patients, 3 had a metastatic sternal tumor, the primary sites of which were as follows: hepatic carcinoma in one case (metastasis 19 years after operation), breast carcinoma in another case (metastasis 5 years after operation), and renal carcinoma in the other case (found simultaneously). Two patients showed local involvement of the sternum: 1 had thymic carcinoma, and the other had myofibrosarcoma. The remaining 9 patients had primary tumors: 4 were osteochondroma, 3 chondrosarcoma, 1 eosinophilic granuloma, 1 non-Hodgekin's lymphoma. En bloc resection of the sternal tumor was performed in all the 14 patients. The defect was repaired with the titanium mesh adjusted to the shape of the defect and fixed with the stainless steel wire. Eleven patients were followed up for a period from 2 months to 4 years, during which no translocation or broken of the titanium mesh was observed. Conclusions Radical en bloc excision remains the treatment of choice for sternal tumors. Sternum defect reconstruction using titanium mesh as a rigid replacement proves appropriate and effective.展开更多
Craniomaxillofacial surgery is difficult due to the complexity of the regional anatomy. Computer-assisted surgery is a promising tool aiming to improve the safety and precision of such surgery. A computer-assisted sur...Craniomaxillofacial surgery is difficult due to the complexity of the regional anatomy. Computer-assisted surgery is a promising tool aiming to improve the safety and precision of such surgery. A computer-assisted surgical navigation approach for reconstruction of mandibular defects using a patient-specific titanium mesh tray and particulate cancellous bone and marrow (PCBM) harvested from bilateral anterior ilia is proposed. This case report involves a large multicystic ameloblastoma affecting the right mandible of a 31-year-old male patient. Following detailed clinical examination, radiological interpretation, and histopathological diagnosis, computer-assisted surgical simulation with a virtual 3-dimensional (3-D) model was designed using surgical planning software based on the pre-operative computed tomography data. Long-span segmental resection of the mandible was planned, and the defect was analyzed for reconstruction using a patient-specific reconstruction titanium mesh tray mediated with computer-aided design and manufacturing (CAD/CAM) techniques. During the actual surgery, the ultrasonic bone cutting instrument in the surgeon’s hand was connected to the navigation system to touch an anatomical position on the patient. Therefore, osteotomies were performed finely and smoothly according to the navigation images of the cutting bone line by sequentially moving the instrument. Finally, a CAD/CAM-mediated titanium mesh tray condensed by PCBM was adapted to the remaining mandibular fragments. Six months postoperatively, the patient had a good mandibular configuration and facial contour. Integration of different technologies, such as software planning and 3-D surgical simulation, combined with intraoperative navigation and CAD/CAM techniques, provides safe and precise mandibular reconstruction surgery.展开更多
To investigate the application of titanium polypropylene mesh in breast reconstruction.In this study,we selected the literature data in recent 4 years to analyze the application of titanium polypropylene mesh in breas...To investigate the application of titanium polypropylene mesh in breast reconstruction.In this study,we selected the literature data in recent 4 years to analyze the application of titanium polypropylene mesh in breast reconstruction.Using the keywords of"breast reconstruction,""titanium polypropylene mesh,^^"application"and"research progress,we analyzed and summarized the related research progress of titanium polypropylene mesh in breast reconstruction.The research was conducted using the analysis of titanium polypropylene mesh,titanium polypropylene mesh in breast reconstruction surgery advantages,adverse complications related to titanium polypropylene mesh in breast reconstruction surgery and preventive measures.By constantly improving these aspects in the research process,the current study has certain value,and may guide the research work of titanium mesh in breast reconstruction.展开更多
Objective To explore the application of scalp rotation flap in reconstruction of infectious scalp defect with titanium mesh exposure. Methods Twelve patients were treated in this group including 4 males and 8 female. ...Objective To explore the application of scalp rotation flap in reconstruction of infectious scalp defect with titanium mesh exposure. Methods Twelve patients were treated in this group including 4 males and 8 female. S The defective size ranged from 2. 0 cm × 5. 0 cm to 0.展开更多
The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing character...The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing characteristics of planetary gear is studied.An improved three-dimensional(3 D)anisotropic tooth surface roughness fractal model is proposed based on the experimental parameters.Considering asperity contact and elastohydrodynamic lubrication(EHL),the contact load and flexibility deformation of the tooth surface are derived,and the deformation compatibility equation of the 3 D loaded tooth contact analysis(3 D-LTCA)method is improved.The asperity of the tooth surface changes the system from EHL to mixed lubrication and reduces the stiffness of the oil film.Compared with the sun planet gear,the asperity has a greater effect on the meshing characteristics of the ring-planet gear.Compared with the proposed method,the comprehensive stiffness obtained by the traditional calculation method considering the lubrication effect is smaller,especially for the ring-planet gear.Compared with roughness,speed and viscosity,the meshing characteristics of planetary gears are most sensitive to torque.展开更多
Objective:To clarify anatomy-related factors in the cervical spine with subsidence of titanium mesh cage (TMC) after one-level cervical corpectomy and fusion. The effect of the cervical posture, segmental curvature an...Objective:To clarify anatomy-related factors in the cervical spine with subsidence of titanium mesh cage (TMC) after one-level cervical corpectomy and fusion. The effect of the cervical posture, segmental curvature and endplate gradient on this postoperative phenomenon was evaluated. Methods: Between August 2003 and March 2006, a total of the 236 patients underwent one-level corpectomy and TMC fusion. Their radiological examinations were reviewed and clinical outcomes evaluated. Results: In the patients who were followed up for 12 months, TMC subsidence occurred in 54 (28.6%) cases. C6 corpectomy had a significant higher risk (26/60, 43.3%) for TMC subsidence, which was correlated with the variation of the gradient of the vertebral endplates against cervical levels. Although the clinical outcome was comparable with those in the literature, the patients may have subsidence-related problems such as neck-shoulder pain, neurological deterioration and instrumental failure. Conclusion: To decrease the incidence of subsidence, TMC design should be optimized to be in line with anatomic characteristics of the cervical spine.展开更多
The numerical simulation of a three-dimensional semiconductor device is a fundamental problem in information science. The mathematical model is defined by an initialboundary nonlinear system of four partial differenti...The numerical simulation of a three-dimensional semiconductor device is a fundamental problem in information science. The mathematical model is defined by an initialboundary nonlinear system of four partial differential equations: an elliptic equation for electric potential, two convection-diffusion equations for electron concentration and hole concentration, and a heat conduction equation for temperature. The first equation is solved by the conservative block-centered method. The concentrations and temperature are computed by the block-centered upwind difference method on a changing mesh, where the block-centered method and upwind approximation are used to discretize the diffusion and convection, respectively. The computations on a changing mesh show very well the local special properties nearby the P-N junction. The upwind scheme is applied to approximate the convection, and numerical dispersion and nonphysical oscillation are avoided. The block-centered difference computes concentrations, temperature, and their adjoint vector functions simultaneously.The local conservation of mass, an important rule in the numerical simulation of a semiconductor device, is preserved during the computations. An optimal order convergence is obtained. Numerical examples are provided to show efficiency and application.展开更多
目的:探讨3D打印个性化钛网的引导骨再生(guided bone regeneration,GBR)术及富血小板纤维蛋白(platelet-rich fibrin,PRF)/Bio-Oss复合物修复牙槽骨缺损的应用。方法:纳入2021年3月至2024年2月于甘肃省中医院口腔颌面外科行GBR骨增量...目的:探讨3D打印个性化钛网的引导骨再生(guided bone regeneration,GBR)术及富血小板纤维蛋白(platelet-rich fibrin,PRF)/Bio-Oss复合物修复牙槽骨缺损的应用。方法:纳入2021年3月至2024年2月于甘肃省中医院口腔颌面外科行GBR骨增量手术的牙槽骨缺损患者68例,随机分为3D组(n=34)与传统组(n=34),3D组使用3D打印个性化钛网及PRF/BioOss复合物,传统组使用传统钛网及PRF/Bio-Oss复合物。对比2组术后2、4、6个月的牙槽骨增加高度、宽度、体积及并发症发生率。结果:3D组术后2、4、6个月的牙槽骨增加高度、宽度与传统组相比,但差异均无统计学意义(P>0.05)。3D组术后2个月、4个月的牙槽骨增加体积均高于传统组,但差异均无统计学意义(P>0.05),术后6个月时牙槽骨增加体积显著高于传统组(P<0.05)。3D组发生早期暴露、晚期暴露、总暴露、创口感染的比例均低于传统组,但差异均无统计学意义(P>0.05)。结论:3D打印个性化钛网及PRF/Bio-Oss复合物的GBR术修复牙槽骨缺损效果良好,术后6个月骨增加体积显著高于应用传统钛网的GBR术,且不影响其安全性,值得临床推广应用。展开更多
文摘<strong>Rationale:</strong> The three-dimensional (3D) computer-made titanium mesh is widely used in the skull repair for those patients receiving decompression of the bone flap. It can restore normal anatomy to a greater extent and make a better appearance. <strong>Case Presentation: </strong>We reported two cases of patients admitted to our hospital who have experienced high scalp tension after skull repair. At first, these two patients underwent decompression of the bone flap, and the physical examination results showed a defect of skull. No neurological symptoms and signs were found. The 3D computed tomography (CT) reconstruction of skull was performed, and then the skull repair with 3D titanium mesh was conducted. But because of high scalp tension, they underwent a second operation, during which we re-trimmed and reduce the arc of the titanium mesh. The scalp incision of both patients healed well and no titanium mesh was exposed. Both patients have a good prognosis. <strong>Lessons:</strong> We highlight that the high tension of scalp due to overstretching after 3D titanium mesh repair for skull defect should be paid much attention to. Trimming and reducing the arc of titanium mesh is an effective treatment for this situation.
文摘In order to study the behavior and interconnection of network devices,graphs structures are used to formulate the properties in terms of mathematical models.Mesh network(meshnet)is a LAN topology in which devices are connected either directly or through some intermediate devices.These terminating and intermediate devices are considered as vertices of graph whereas wired or wireless connections among these devices are shown as edges of graph.Topological indices are used to reflect structural property of graphs in form of one real number.This structural invariant has revolutionized the field of chemistry to identify molecular descriptors of chemical compounds.These indices are extensively used for establishing relationships between the structure of nanotubes and their physico-chemical properties.In this paper a representation of sodium chloride(NaCl)is studied,because structure of NaCl is same as the Cartesian product of three paths of length exactly like a mesh network.In this way the general formula obtained in this paper can be used in chemistry as well as for any degree-based topological polynomials of three-dimensional mesh networks.
基金the financial support from the National Natural Science Foundation of China(Nos.21722604 and 21776116)China Postdoctoral Science Foundation(2020M671365)+2 种基金Jiangsu Postdoctoral Research Funding Program(No.2021K343C)Natural Science Foundation of Jiangsu Province(No.BK20190243)the Society Development Fund of Zhenjiang City(SH2020020)。
文摘A series of three-dimensional ordered macroporous(3 DOM)W-TiO_(2)catalysts have been prepared through a facile colloidal crystal template method.The prepared materials characterized in detail exhibited enhanced catalytic activity in aerobic oxidative desulfurization process.The experimental results indicated that the as-prepared materials possessed excellent 3 DOM structure,which is beneficial for the catalytic activity.The sample 3 DOM W-TiO_(2)-20 exhibited the highest activity in ODS process,and the sulfur removal can reach 98%in 6 h.Furthermore,the oxidative product was also analyzed in the reaction process.
基金This study was supported by National Natural Science Foundation of China(Grant Nos.81970986,81771125,X.C.and 11872135,12072055 C.W.)。
文摘Guided bone regeneration(GBR)is an effective and simple method for bone augmentation,which is often used to reconstruct the alveolar ridge when the bone defect occurs in the implant area.Titanium mesh has expanded the indications of GBR technology due to its excellent mechanical properties and biocompatibility,so that the GBR technology can be used to repair alveolar ridges with larger bone defects,and can obtain excellent and stable bone augmentation results.Currently,GBR with titanium mesh has various clinical applications,including different clinical procedures.Bone graft materials,titanium mesh covering methods,and titanium mesh fixing methods are also optional.Moreover,the research of GBR with titanium mesh has led to multifarious progresses in digitalization and material modification.This article reviews the properties of titanium mesh and the difference of titanium mesh with other barrier membranes;the current clinical application of titanium mesh in bone augmentation;common complications and management and prevention methods in the application of titanium mesh;and research progress of titanium mesh in digitization and material modification.Hoping to provide a reference for further improvement of titanium mesh in clinical application and related research of titanium mesh.
基金This study was supported by National Key R&D Program of China(2019YFA0110600)National Natural Science Foundation of China(81970986,81771125)Exploration and R&D Project of West China Hospital of Stomatology(LCYJ2020-DC-1).
文摘Guided bone regeneration(GBR)uses resorbable and non-resorbable membranes as biological barriers.This study compared the differences in hard tissue stability between GBR using evidence-based digital titanium mesh and resorbable collagen membranes during implant placement.A total of 40 patients(65 implant sites)were enrolled and divided into two groups:resorbable membrane and digital titanium mesh groups.The alveolar bone was analyzed at two-and three-dimensional levels using conebeam computed tomography and by reconstructing and superimposing the hard tissues at four time points:preoperatively,postoperatively,before second-stage surgery,and 1 year after loading.The use of digital titanium mesh showed less alveolar bone resorption in vertical and horizontal directions two-dimensionally before the second-stage surgery and 1 year after loading.Regarding volumetric stability,the percentage of resorption after 6 months of healing with resorbable membrane coverage reached 37.5%.However,it was only 23.4%with titanium mesh.Although postoperative bone volume was greater at all labial sites with resorbable membrane than with digital titanium mesh,after substantial bone resorption within 1 year of loading,the labial bone thickness at the upper part of implants was thinner with resorbable membrane than with digital titanium mesh.Furthermore,digital titanium meshes made according to ideal bone arch contour reduced soft tissue irritation,and the exposure rate was only 10%.Therefore,although both resorbable membrane and digital titanium mesh in GBR were able to successfully reconstruct the bone defect,digital titanium meshes were better at maintaining the hard tissue volume in the osteogenic space.
文摘Objective To evaluate the use of titanium mesh reconstruction after sternal tumor resection. Methods From January 2007 to January 2011, 14 patients with sternal tumors were admitted into Peking Union Medical Hospital. The clinical characteristics, surgical resection, and technique of reconstruction were reviewed. Results Of the 14 patients, 3 had a metastatic sternal tumor, the primary sites of which were as follows: hepatic carcinoma in one case (metastasis 19 years after operation), breast carcinoma in another case (metastasis 5 years after operation), and renal carcinoma in the other case (found simultaneously). Two patients showed local involvement of the sternum: 1 had thymic carcinoma, and the other had myofibrosarcoma. The remaining 9 patients had primary tumors: 4 were osteochondroma, 3 chondrosarcoma, 1 eosinophilic granuloma, 1 non-Hodgekin's lymphoma. En bloc resection of the sternal tumor was performed in all the 14 patients. The defect was repaired with the titanium mesh adjusted to the shape of the defect and fixed with the stainless steel wire. Eleven patients were followed up for a period from 2 months to 4 years, during which no translocation or broken of the titanium mesh was observed. Conclusions Radical en bloc excision remains the treatment of choice for sternal tumors. Sternum defect reconstruction using titanium mesh as a rigid replacement proves appropriate and effective.
文摘Craniomaxillofacial surgery is difficult due to the complexity of the regional anatomy. Computer-assisted surgery is a promising tool aiming to improve the safety and precision of such surgery. A computer-assisted surgical navigation approach for reconstruction of mandibular defects using a patient-specific titanium mesh tray and particulate cancellous bone and marrow (PCBM) harvested from bilateral anterior ilia is proposed. This case report involves a large multicystic ameloblastoma affecting the right mandible of a 31-year-old male patient. Following detailed clinical examination, radiological interpretation, and histopathological diagnosis, computer-assisted surgical simulation with a virtual 3-dimensional (3-D) model was designed using surgical planning software based on the pre-operative computed tomography data. Long-span segmental resection of the mandible was planned, and the defect was analyzed for reconstruction using a patient-specific reconstruction titanium mesh tray mediated with computer-aided design and manufacturing (CAD/CAM) techniques. During the actual surgery, the ultrasonic bone cutting instrument in the surgeon’s hand was connected to the navigation system to touch an anatomical position on the patient. Therefore, osteotomies were performed finely and smoothly according to the navigation images of the cutting bone line by sequentially moving the instrument. Finally, a CAD/CAM-mediated titanium mesh tray condensed by PCBM was adapted to the remaining mandibular fragments. Six months postoperatively, the patient had a good mandibular configuration and facial contour. Integration of different technologies, such as software planning and 3-D surgical simulation, combined with intraoperative navigation and CAD/CAM techniques, provides safe and precise mandibular reconstruction surgery.
文摘To investigate the application of titanium polypropylene mesh in breast reconstruction.In this study,we selected the literature data in recent 4 years to analyze the application of titanium polypropylene mesh in breast reconstruction.Using the keywords of"breast reconstruction,""titanium polypropylene mesh,^^"application"and"research progress,we analyzed and summarized the related research progress of titanium polypropylene mesh in breast reconstruction.The research was conducted using the analysis of titanium polypropylene mesh,titanium polypropylene mesh in breast reconstruction surgery advantages,adverse complications related to titanium polypropylene mesh in breast reconstruction surgery and preventive measures.By constantly improving these aspects in the research process,the current study has certain value,and may guide the research work of titanium mesh in breast reconstruction.
文摘Objective To explore the application of scalp rotation flap in reconstruction of infectious scalp defect with titanium mesh exposure. Methods Twelve patients were treated in this group including 4 males and 8 female. S The defective size ranged from 2. 0 cm × 5. 0 cm to 0.
基金Project(2024A1515240020)supported by the Guangdong Basic and Applied Basic Research Foundation,China。
文摘The contact characteristics of the rough tooth surface during the meshing process are significantly affected by the lubrication state.The coupling effect of tooth surface roughness and lubrication on meshing characteristics of planetary gear is studied.An improved three-dimensional(3 D)anisotropic tooth surface roughness fractal model is proposed based on the experimental parameters.Considering asperity contact and elastohydrodynamic lubrication(EHL),the contact load and flexibility deformation of the tooth surface are derived,and the deformation compatibility equation of the 3 D loaded tooth contact analysis(3 D-LTCA)method is improved.The asperity of the tooth surface changes the system from EHL to mixed lubrication and reduces the stiffness of the oil film.Compared with the sun planet gear,the asperity has a greater effect on the meshing characteristics of the ring-planet gear.Compared with the proposed method,the comprehensive stiffness obtained by the traditional calculation method considering the lubrication effect is smaller,especially for the ring-planet gear.Compared with roughness,speed and viscosity,the meshing characteristics of planetary gears are most sensitive to torque.
文摘Objective:To clarify anatomy-related factors in the cervical spine with subsidence of titanium mesh cage (TMC) after one-level cervical corpectomy and fusion. The effect of the cervical posture, segmental curvature and endplate gradient on this postoperative phenomenon was evaluated. Methods: Between August 2003 and March 2006, a total of the 236 patients underwent one-level corpectomy and TMC fusion. Their radiological examinations were reviewed and clinical outcomes evaluated. Results: In the patients who were followed up for 12 months, TMC subsidence occurred in 54 (28.6%) cases. C6 corpectomy had a significant higher risk (26/60, 43.3%) for TMC subsidence, which was correlated with the variation of the gradient of the vertebral endplates against cervical levels. Although the clinical outcome was comparable with those in the literature, the patients may have subsidence-related problems such as neck-shoulder pain, neurological deterioration and instrumental failure. Conclusion: To decrease the incidence of subsidence, TMC design should be optimized to be in line with anatomic characteristics of the cervical spine.
基金supported the Natural Science Foundation of Shandong Province(ZR2016AM08)Natural Science Foundation of Hunan Province(2018JJ2028)National Natural Science Foundation of China(11871312).
文摘The numerical simulation of a three-dimensional semiconductor device is a fundamental problem in information science. The mathematical model is defined by an initialboundary nonlinear system of four partial differential equations: an elliptic equation for electric potential, two convection-diffusion equations for electron concentration and hole concentration, and a heat conduction equation for temperature. The first equation is solved by the conservative block-centered method. The concentrations and temperature are computed by the block-centered upwind difference method on a changing mesh, where the block-centered method and upwind approximation are used to discretize the diffusion and convection, respectively. The computations on a changing mesh show very well the local special properties nearby the P-N junction. The upwind scheme is applied to approximate the convection, and numerical dispersion and nonphysical oscillation are avoided. The block-centered difference computes concentrations, temperature, and their adjoint vector functions simultaneously.The local conservation of mass, an important rule in the numerical simulation of a semiconductor device, is preserved during the computations. An optimal order convergence is obtained. Numerical examples are provided to show efficiency and application.
文摘目的:探讨3D打印个性化钛网的引导骨再生(guided bone regeneration,GBR)术及富血小板纤维蛋白(platelet-rich fibrin,PRF)/Bio-Oss复合物修复牙槽骨缺损的应用。方法:纳入2021年3月至2024年2月于甘肃省中医院口腔颌面外科行GBR骨增量手术的牙槽骨缺损患者68例,随机分为3D组(n=34)与传统组(n=34),3D组使用3D打印个性化钛网及PRF/BioOss复合物,传统组使用传统钛网及PRF/Bio-Oss复合物。对比2组术后2、4、6个月的牙槽骨增加高度、宽度、体积及并发症发生率。结果:3D组术后2、4、6个月的牙槽骨增加高度、宽度与传统组相比,但差异均无统计学意义(P>0.05)。3D组术后2个月、4个月的牙槽骨增加体积均高于传统组,但差异均无统计学意义(P>0.05),术后6个月时牙槽骨增加体积显著高于传统组(P<0.05)。3D组发生早期暴露、晚期暴露、总暴露、创口感染的比例均低于传统组,但差异均无统计学意义(P>0.05)。结论:3D打印个性化钛网及PRF/Bio-Oss复合物的GBR术修复牙槽骨缺损效果良好,术后6个月骨增加体积显著高于应用传统钛网的GBR术,且不影响其安全性,值得临床推广应用。
