目的 厘清临床上膝关节软骨下功能不全骨折(subchondral insufficiency fracture of the knee,SIFK)和膝关节骨坏死(osteonecrosis of the knee,ONK)疾病术语的使用,同时总结该疾病的研究进展。方法 广泛查阅近年来国内外SIFK和ONK领域...目的 厘清临床上膝关节软骨下功能不全骨折(subchondral insufficiency fracture of the knee,SIFK)和膝关节骨坏死(osteonecrosis of the knee,ONK)疾病术语的使用,同时总结该疾病的研究进展。方法 广泛查阅近年来国内外SIFK和ONK领域研究文献,从当前概念、病因及发病机制、临床和影像学表现以及治疗方案、预后等方面阐述该疾病研究进展。结果 SIFK确切病因仍有争论,具体发病机制也未完全阐明,软骨下骨折为主要病理特征改变。SIFK主要影响65岁以上女性人群,表现为突然发作的严重且持续疼痛;MRI是诊断早期SIFK的“金标准”,骨髓水肿样信号和受影响股骨髁的软骨下低信号线是典型表现。一般而言,如果骨形态保持、没有发生软骨下骨塌陷,首选保守治疗,如果保守治疗3~4个月后临床或影像学无改善,应考虑手术干预。结论 考虑骨样本病理特征,宜采用SIFK描述ONK。早期诊断和管理对于改善SIFK患者预后很重要。展开更多
Organic and inorganic phase change materials(PCMs) are considered potential materials for thermal energy storage(TES) with different phase change characteristics. In this study, a novel organic-inorganic composite pha...Organic and inorganic phase change materials(PCMs) are considered potential materials for thermal energy storage(TES) with different phase change characteristics. In this study, a novel organic-inorganic composite phase change material(PCM) called disodium hydrogen phosphate dodecahydrate-lauric-palmitic acid(D-LA-PACM) was prepared. Expanded graphite(EG) was selected as the support material, and the novel organic-inorganic form-stable PCM called D-LA-PAPCM/EG was prepared using the vacuum adsorption method. Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, leakage testing, melting and solidification cycle testing, thermal conductivity testing, scanning electron microscopy observation of the micromorphology, and other characterization methods were used to study the microstructure and morphology, thermal physical parameters, thermal conductivity, stability of the PCMs, and the comprehensive material properties of D-LA-PAPCM under the composite action of EG. Results indicated that the melting and freezing temperatures and latent heats of D-LA-PAPCM/EG were measured to be 31.6℃ and 34.3℃ and 142.9 and 142.8 J/g, respectively. Although some of the lauric-palmitic acid(LA-PA) and disodium hydrogen phosphate dodecahydrate(DHPD) separated in the multiple porous structures of EG after 1000 cycles, they could still absorb and release latent heats independently, with D-LA-PAPCM/EG still exhibiting good thermal stability. The thermal conductivity of D-LA-PAPCM/EG was 1.361 W/(m·K). Therefore, the material and thermal properties of the prepared D-LA-PAPCM/EG indicate that it could be well used as a feasible material for energy-saving phase change floor units in indoor TES systems.展开更多
To optimize the structure of the burner,improve the combustion performance,and reduce the emission of NO_(x),a self-circulating low NO_(x)combustion technology was used to design a new type of flue gas self-circulatin...To optimize the structure of the burner,improve the combustion performance,and reduce the emission of NO_(x),a self-circulating low NO_(x)combustion technology was used to design a new type of flue gas self-circulating low NO_(x)burner.Based on previous research on the numerical model of combustion and the composition of mixed gas on combustion and NO_(x)emissions,the effect of various factors on the ejection coefficient of the flue gas self-circulating structure was analyzed using the orthogonal test method,and the burner operating parameters,such as preheating temperature and excess air coefficient,were deeply studied through the three-dimensional finite element numerical model in this paper.The results show that the diameter ratio of the nozzle and the length of the cylindrical section of the flue gas self-circulating structure have great influence on its ejection and mixing ability.The optimal ejection coefficient was 0.4829.Overall,the amount of NO_(x)emissions greatly increased from 6.23×10^(-6)(volume fraction)at the preheating temperature 973 K to 3.5×10^(-3)at preheating temperature 1573 K.When the excess air coefficient decreased from 1.2 to 1,the maximum combustion temperature decreased from 2036.3 K to 1954.22 K,and the NO_(x)emissions decreased from 352.29×10^(-6)to 159.73×10^(-6).展开更多
文摘目的 厘清临床上膝关节软骨下功能不全骨折(subchondral insufficiency fracture of the knee,SIFK)和膝关节骨坏死(osteonecrosis of the knee,ONK)疾病术语的使用,同时总结该疾病的研究进展。方法 广泛查阅近年来国内外SIFK和ONK领域研究文献,从当前概念、病因及发病机制、临床和影像学表现以及治疗方案、预后等方面阐述该疾病研究进展。结果 SIFK确切病因仍有争论,具体发病机制也未完全阐明,软骨下骨折为主要病理特征改变。SIFK主要影响65岁以上女性人群,表现为突然发作的严重且持续疼痛;MRI是诊断早期SIFK的“金标准”,骨髓水肿样信号和受影响股骨髁的软骨下低信号线是典型表现。一般而言,如果骨形态保持、没有发生软骨下骨塌陷,首选保守治疗,如果保守治疗3~4个月后临床或影像学无改善,应考虑手术干预。结论 考虑骨样本病理特征,宜采用SIFK描述ONK。早期诊断和管理对于改善SIFK患者预后很重要。
基金The authors gratefully acknowledge the Fundamental Research Funds for the Central Universities of China(FRF-TP-17-057A1 and FRF-TP-18-074A1)the China Postdoctoral Science Foundation(No.2019M650491)the National Natural Science Foundation of China(No.11801029).
文摘Organic and inorganic phase change materials(PCMs) are considered potential materials for thermal energy storage(TES) with different phase change characteristics. In this study, a novel organic-inorganic composite phase change material(PCM) called disodium hydrogen phosphate dodecahydrate-lauric-palmitic acid(D-LA-PACM) was prepared. Expanded graphite(EG) was selected as the support material, and the novel organic-inorganic form-stable PCM called D-LA-PAPCM/EG was prepared using the vacuum adsorption method. Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, leakage testing, melting and solidification cycle testing, thermal conductivity testing, scanning electron microscopy observation of the micromorphology, and other characterization methods were used to study the microstructure and morphology, thermal physical parameters, thermal conductivity, stability of the PCMs, and the comprehensive material properties of D-LA-PAPCM under the composite action of EG. Results indicated that the melting and freezing temperatures and latent heats of D-LA-PAPCM/EG were measured to be 31.6℃ and 34.3℃ and 142.9 and 142.8 J/g, respectively. Although some of the lauric-palmitic acid(LA-PA) and disodium hydrogen phosphate dodecahydrate(DHPD) separated in the multiple porous structures of EG after 1000 cycles, they could still absorb and release latent heats independently, with D-LA-PAPCM/EG still exhibiting good thermal stability. The thermal conductivity of D-LA-PAPCM/EG was 1.361 W/(m·K). Therefore, the material and thermal properties of the prepared D-LA-PAPCM/EG indicate that it could be well used as a feasible material for energy-saving phase change floor units in indoor TES systems.
基金supported by the Fundamental Research Funds for the Central Universities of China(FRF-TP-18-074A1,FRF-BD-20-09A)the China Postdoctoral Science Foundation(No.2019M650491)the National Natural Science Foundation of China(No.11801029)。
文摘To optimize the structure of the burner,improve the combustion performance,and reduce the emission of NO_(x),a self-circulating low NO_(x)combustion technology was used to design a new type of flue gas self-circulating low NO_(x)burner.Based on previous research on the numerical model of combustion and the composition of mixed gas on combustion and NO_(x)emissions,the effect of various factors on the ejection coefficient of the flue gas self-circulating structure was analyzed using the orthogonal test method,and the burner operating parameters,such as preheating temperature and excess air coefficient,were deeply studied through the three-dimensional finite element numerical model in this paper.The results show that the diameter ratio of the nozzle and the length of the cylindrical section of the flue gas self-circulating structure have great influence on its ejection and mixing ability.The optimal ejection coefficient was 0.4829.Overall,the amount of NO_(x)emissions greatly increased from 6.23×10^(-6)(volume fraction)at the preheating temperature 973 K to 3.5×10^(-3)at preheating temperature 1573 K.When the excess air coefficient decreased from 1.2 to 1,the maximum combustion temperature decreased from 2036.3 K to 1954.22 K,and the NO_(x)emissions decreased from 352.29×10^(-6)to 159.73×10^(-6).
