AIM:To present computed tomography(CT) findings of different histological subtypes of parotid gland masses in detail and to establish diagnostic strategy.METHODS:From January 2009 to November 2011,56 patients were col...AIM:To present computed tomography(CT) findings of different histological subtypes of parotid gland masses in detail and to establish diagnostic strategy.METHODS:From January 2009 to November 2011,56 patients were collected through the histopathology and Picture Archiving and Communication Systems records,which revealed 5 basal cell adenoma(BCA),16 pleomorphic adenoma(PA),25 Warthin's tumor(War-T),3 Kimura's disease(KD) and 7 parotid carcinoma(PCa) cases.All the CT images were retrospectively analyzed by two radiologists in consensus,based on their description of morphology(location,number,size,margin and fibrous capsule) and enhancement patterns of masses.In addition,the diagnostic efficiency of diagnostic strategy is tested.RESULTS:War-T and BCA patients' mean age was 59.9 ± 12.6 years and 58.4 ± 18.2 years;the significant difference was seen in War-T vs PA and BCA vs PA.About 40% of War-Ts presented with bilateral multifocal lesions,a higher ratio than others.Seventy two percent of War-Ts were limited to the superficial lobe,followed by BCA 60% and PA 40%.Vessel facing sign and enlarged lymph nodes were both frequent in War-T,which respectively accounts for 84% and 76% of cases.Rapid contrast enhancement and decreases were unique for War-T.BCA and PA showed obvious delayed enhancement.The diagnostic strategy of parotid gland tumor had a good diagnostic efficiency,with high accuracy,sensitivity and specificity.CONCLUSION:Determination of the histological subtypes of parotid gland masses might be possible based on CT findings and clinical data.A diagnostic strategy with high diagnostic efficiency was established.展开更多
In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and mechanical properties suitable for bone tissue engineering. In this pape...In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and mechanical properties suitable for bone tissue engineering. In this paper, we characterize the porous Ti6Al4V implant, which is one of the most promising and attractive biomedical applications due to the similarity of its modulus to human bones. We describe the mechanical properties of this implant, which we suggest is capable of providing important biological functions for bone tissue regeneration. We characterize a novel bionic design and fabrication process for porous implants. A design concept of “reducing dimensions and designing layer by layer” was used to construct layered slice and rod-connected mesh structure (LSRCMS) implants. Porous LSRCMS implants with different parameters and porosities were fabricated by selective laser melting (SLM). Printed samples were evaluated by microstructure characterization, specific mechanical properties were analyzed by mechanical tests, and finite element analysis was used to digitally calculate the stress characteristics of the LSRCMS under loading forces. Our results show that the samples fabricated by SLM had good structure printing quality with reasonable pore sizes. The porosity, pore size, and strut thickness of manufactured samples ranged from (60.95± 0.27)% to (81.23±0.32)%,(480±28) to (685±31)μm, and (263±28) to (265±28)μm, respectively. The compression results show that the Young’s modulus and the yield strength ranged from (2.23±0.03) to (6.36±0.06) GPa and (21.36±0.42) to (122.85±3.85) MPa, respectively. We also show that the Young’s modulus and yield strength of the LSRCMS samples can be predicted by the Gibson-Ashby model. Further, we prove the structural stability of our novel design by finite element analysis. Our results illustrate that our novel SLM-fabricated porous Ti6Al4V scaffolds based on an LSRCMS are a promising material for bone implants, and are potentially applicable to the field o展开更多
This paper presents a robust algorithm to generate support for fused deposition modeling (FDM). Since many flaws appear in most stereo lithography (STL) models, this algorithm utilizes slice data as input. A top-down ...This paper presents a robust algorithm to generate support for fused deposition modeling (FDM). Since many flaws appear in most stereo lithography (STL) models, this algorithm utilizes slice data as input. A top-down approach was used to calculate the support slice layer by layer. The generation algorithm was described in detail including the slice grouping, oriental bounding box (OBB) calculation, offsetting, and Boolean operations. Several cases are given to validate the efficiency and robustness of the procedure. The algorithm provides necessary support not only for hanging surface but also for hanging vertexes and edges with O(n) time complexity, where n is the number of layers. The algorithm fully utilizes the parts’ self-support ability and reduces support volume to the maximum extent. This slice data based algorithm has the same efficiency as the STL based algorithm but is more stable, which significantly enhances the robustness of the support generation process.展开更多
Although slice methods are simple and effective slope stability analysis approaches,they are statically indeterminate.Several modifications of the slice method,such as the Spencer,MorgensternPrice,and Chen-Morgenstern...Although slice methods are simple and effective slope stability analysis approaches,they are statically indeterminate.Several modifications of the slice method,such as the Spencer,MorgensternPrice,and Chen-Morgenstern methods,are statically determinate and solvable as they assume the inter-slice force inclination angle;however,there is a small gap between the assumptions and actual landslide stability analysis.Through reasonable theoretical analysis,the Su slice method provides a reliable approach for determining the inter-slice force inclination angle that can be used in slice analysis to accurately analyse,calculate,and evaluate the stability of landslides.However,the Su slice method requires further research and analysis,especially in terms of the parameter values sinλbiandρ.In this study,we investigated more accurate methods for calculating the parameters sinλbiandρ.In addition,an adjustment coefficient(μ)was introduced to improve the solution method for the inter-slice force inclination angle.The inter-slice force inclination and safety factors of three landslides with arc-shaped slip surfaces and one landslide with a polyline-shaped slip surface were analysed and compared using the different slice methods.The improved inter-slice force inclination not only satisfies the calculation of static force equilibrium condition but also satisfies the calculation of both the force and moment equilibrium conditions.The improved method for calculating inter-slice force inclination presented the best correlation.The safety factors calculated using the improved Su slice method were close to those obtained using numerical simulations and the Morgenstern-Price method.Despite negligible differences among the safety factors calculated using the Su slice,improved Su slice,and M-P methods,the accuracy of the improved Su slice method was better than the M-P method in terms of inter-slice force inclination angles which can be useful to improve protection engineering design.展开更多
Based on a shallow-buried coal seam covered with thick loose layers in hilly loess areas of western China,we developed a mechanical model for a mining slope with slope stability analysis, and studied the mechanism of ...Based on a shallow-buried coal seam covered with thick loose layers in hilly loess areas of western China,we developed a mechanical model for a mining slope with slope stability analysis, and studied the mechanism of formation and development of a sliding ground fissure by the circular sliding slice method.Moreover, we established a prediction model of a sliding fissure based on a mechanical mechanism,and verified its reliability on face 52,304, an engineering example, situated at Daliuta coal mine of Shendong mining area in western China. The results show that the stress state of a mining slope is changed by its gravity and additional stress from the shallow-buried coal seam and gully terrain. The mining slope is found to be most unstable when the ratio of the down-sliding to anti-sliding force is the maximum, causing local fractures and sliding fissures. The predicted angles for the sliding fissure of face 52,304 on both sides of the slope are found to be 64.2° and 82.4°, which are in agreement with the experimental data.展开更多
文摘AIM:To present computed tomography(CT) findings of different histological subtypes of parotid gland masses in detail and to establish diagnostic strategy.METHODS:From January 2009 to November 2011,56 patients were collected through the histopathology and Picture Archiving and Communication Systems records,which revealed 5 basal cell adenoma(BCA),16 pleomorphic adenoma(PA),25 Warthin's tumor(War-T),3 Kimura's disease(KD) and 7 parotid carcinoma(PCa) cases.All the CT images were retrospectively analyzed by two radiologists in consensus,based on their description of morphology(location,number,size,margin and fibrous capsule) and enhancement patterns of masses.In addition,the diagnostic efficiency of diagnostic strategy is tested.RESULTS:War-T and BCA patients' mean age was 59.9 ± 12.6 years and 58.4 ± 18.2 years;the significant difference was seen in War-T vs PA and BCA vs PA.About 40% of War-Ts presented with bilateral multifocal lesions,a higher ratio than others.Seventy two percent of War-Ts were limited to the superficial lobe,followed by BCA 60% and PA 40%.Vessel facing sign and enlarged lymph nodes were both frequent in War-T,which respectively accounts for 84% and 76% of cases.Rapid contrast enhancement and decreases were unique for War-T.BCA and PA showed obvious delayed enhancement.The diagnostic strategy of parotid gland tumor had a good diagnostic efficiency,with high accuracy,sensitivity and specificity.CONCLUSION:Determination of the histological subtypes of parotid gland masses might be possible based on CT findings and clinical data.A diagnostic strategy with high diagnostic efficiency was established.
文摘影响聚合物溶液粘度的外来因素是多方面的,包括pH值、温度、各种金属阳离子、搅拌速度和时间等.对以上诸因素进行了全面的实验分析,并确定了现场配制时应控制的主要指标范围:pH值应控制在6～9,温度以15～30 ℃为宜,并且应当尽量用矿化度较低的清水配制,配制时搅拌速度应控制在150 r/min以下,搅拌时间不应超过50 min.
基金Project supported by the National Natural Science Foundation of China(No.51775506)the Zhejiang Provincial Natural Science Foundation of China(No.LY18E050022)+2 种基金the Public Welfare Technology Application Research Project of Zhejiang Province(Nos.LGG19E050022 and 2017C33115)the Zhejiang Provincial Science&Technology Project for Medicine&Health(No.2018KY878)the Open Foundation of Zhejiang Provincial Top Key Discipline of Mechanical Engineering of Hangzhou Dianzi University,China
文摘In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and mechanical properties suitable for bone tissue engineering. In this paper, we characterize the porous Ti6Al4V implant, which is one of the most promising and attractive biomedical applications due to the similarity of its modulus to human bones. We describe the mechanical properties of this implant, which we suggest is capable of providing important biological functions for bone tissue regeneration. We characterize a novel bionic design and fabrication process for porous implants. A design concept of “reducing dimensions and designing layer by layer” was used to construct layered slice and rod-connected mesh structure (LSRCMS) implants. Porous LSRCMS implants with different parameters and porosities were fabricated by selective laser melting (SLM). Printed samples were evaluated by microstructure characterization, specific mechanical properties were analyzed by mechanical tests, and finite element analysis was used to digitally calculate the stress characteristics of the LSRCMS under loading forces. Our results show that the samples fabricated by SLM had good structure printing quality with reasonable pore sizes. The porosity, pore size, and strut thickness of manufactured samples ranged from (60.95± 0.27)% to (81.23±0.32)%,(480±28) to (685±31)μm, and (263±28) to (265±28)μm, respectively. The compression results show that the Young’s modulus and the yield strength ranged from (2.23±0.03) to (6.36±0.06) GPa and (21.36±0.42) to (122.85±3.85) MPa, respectively. We also show that the Young’s modulus and yield strength of the LSRCMS samples can be predicted by the Gibson-Ashby model. Further, we prove the structural stability of our novel design by finite element analysis. Our results illustrate that our novel SLM-fabricated porous Ti6Al4V scaffolds based on an LSRCMS are a promising material for bone implants, and are potentially applicable to the field o
基金Supported by the Natural Science Fund Project of Hubei Province of China (2004ABC001)
文摘This paper presents a robust algorithm to generate support for fused deposition modeling (FDM). Since many flaws appear in most stereo lithography (STL) models, this algorithm utilizes slice data as input. A top-down approach was used to calculate the support slice layer by layer. The generation algorithm was described in detail including the slice grouping, oriental bounding box (OBB) calculation, offsetting, and Boolean operations. Several cases are given to validate the efficiency and robustness of the procedure. The algorithm provides necessary support not only for hanging surface but also for hanging vertexes and edges with O(n) time complexity, where n is the number of layers. The algorithm fully utilizes the parts’ self-support ability and reduces support volume to the maximum extent. This slice data based algorithm has the same efficiency as the STL based algorithm but is more stable, which significantly enhances the robustness of the support generation process.
基金evolution mechanism and prevention countermeasures of the Outang landslide in the Three Gorges Reservoir Area(No.20C0023)research projectthe geological safety risk investigation,evaluation and control of key resettlement towns in the Three Gorges Reservoir Area(No.HBHDZFCG2021025)+2 种基金the National Natural Science Foundation of China(No.42077268)the Chongqing Geological Disaster Prevention and Control Center of China(No.20C0023)the open fund of state key laboratory of geohazard prevention and geoenvironment protection(No.SKLGP2020K015)。
文摘Although slice methods are simple and effective slope stability analysis approaches,they are statically indeterminate.Several modifications of the slice method,such as the Spencer,MorgensternPrice,and Chen-Morgenstern methods,are statically determinate and solvable as they assume the inter-slice force inclination angle;however,there is a small gap between the assumptions and actual landslide stability analysis.Through reasonable theoretical analysis,the Su slice method provides a reliable approach for determining the inter-slice force inclination angle that can be used in slice analysis to accurately analyse,calculate,and evaluate the stability of landslides.However,the Su slice method requires further research and analysis,especially in terms of the parameter values sinλbiandρ.In this study,we investigated more accurate methods for calculating the parameters sinλbiandρ.In addition,an adjustment coefficient(μ)was introduced to improve the solution method for the inter-slice force inclination angle.The inter-slice force inclination and safety factors of three landslides with arc-shaped slip surfaces and one landslide with a polyline-shaped slip surface were analysed and compared using the different slice methods.The improved inter-slice force inclination not only satisfies the calculation of static force equilibrium condition but also satisfies the calculation of both the force and moment equilibrium conditions.The improved method for calculating inter-slice force inclination presented the best correlation.The safety factors calculated using the improved Su slice method were close to those obtained using numerical simulations and the Morgenstern-Price method.Despite negligible differences among the safety factors calculated using the Su slice,improved Su slice,and M-P methods,the accuracy of the improved Su slice method was better than the M-P method in terms of inter-slice force inclination angles which can be useful to improve protection engineering design.
基金Projects funded by the National Key Basic Research Development Program(No.2013CB227904)the National Natural Science Foundation of China(No.41272389)+1 种基金China Postdoctoral Science Foundation(No.2014M561931)the Natural Science Foundation of Hebei Province(No.D2014402007)
文摘Based on a shallow-buried coal seam covered with thick loose layers in hilly loess areas of western China,we developed a mechanical model for a mining slope with slope stability analysis, and studied the mechanism of formation and development of a sliding ground fissure by the circular sliding slice method.Moreover, we established a prediction model of a sliding fissure based on a mechanical mechanism,and verified its reliability on face 52,304, an engineering example, situated at Daliuta coal mine of Shendong mining area in western China. The results show that the stress state of a mining slope is changed by its gravity and additional stress from the shallow-buried coal seam and gully terrain. The mining slope is found to be most unstable when the ratio of the down-sliding to anti-sliding force is the maximum, causing local fractures and sliding fissures. The predicted angles for the sliding fissure of face 52,304 on both sides of the slope are found to be 64.2° and 82.4°, which are in agreement with the experimental data.
