In this study, we have investigated how the dielectric loss tangent and permittivity of AlN ceramics are affected by factors such as powder mixing methods, milling time, sintering temperature, and the addition of a se...In this study, we have investigated how the dielectric loss tangent and permittivity of AlN ceramics are affected by factors such as powder mixing methods, milling time, sintering temperature, and the addition of a second conductive phase. All ceramic samples were prepared by spark plasma sintering(SPS) under a pressure of 30 MPa. AlN composite ceramics sintered with 30wt%–40wt% SiC at 1600°C for 5 min exhibited the best dielectric loss tangent, which is greater than 0.3. In addition to AlN and β-SiC, the samples also contained 2H-SiC and Fe5Si3, as detected by X-ray difraction(XRD). The relative densities of the sintered ceramics were higher than 93%. Experimental results indicate that nano-SiC has a strong capability of absorbing electromagnetic waves. The dielectric constant and dielectric loss of AlN-SiC ceramics with the same content of SiC decreased as the frequency of electromagnetic waves increased from 1 kHz to 1 MHz.展开更多
Objective:To explore the expression of IL-2 and IL-11 and its significance in patients with ankylosing spondylitis(AS).Methods:A total of 48 active AS patients in our hospital and 40 normal control subjects were selec...Objective:To explore the expression of IL-2 and IL-11 and its significance in patients with ankylosing spondylitis(AS).Methods:A total of 48 active AS patients in our hospital and 40 normal control subjects were selected in our study.Bath ankylosing spondylitis disease activity index(BASDAI),Bath ankylosing spondylitis functional index(BASFI),Bath ankylosing spondylitis metrology index(BASMI),ESR and CRP expression levels were compared before treatment,12 h after treatment and 24 h after treatment.IL-2 and IL-11 expression were also compared between these two groups.Results:The BASDAI score,BASH score and BASMI score of the AS patients before treatment significantly decreased compared with those 12 weeks and 24 weeks after treatment(P【0.05).ESB and CRP levels of the AS patients 12 weeks and 24 weeks after treatment significantly decreased compared with those before treatment(P【0.05).Difference was significant in serum IL-2 and IL-11 levels between 12 weeks and 24 weeks after treatment and before treatment(P【0.05).And no statistically significance was observed for serum IL-2 and IL-11 levels between normal control group and those of patients in AS group 24 weeks after treatment(P】0.05). Pearson’s linear-correlation analysis showed that serum IL-2 level had a positive correlation with BASDAI,BASFI,BASMI,ESR and CRP(r=0.661.0.547,0.474,0.362,0.416,P【0.05) and serum IL-11 level had a negative correlation with BASDAI,BASFI,BASMI,ESR and CRP(r=-0.629, -0.412,-0.422,-0.387,-0.408,-0.315,P【0.05).Conclusions:Serum levels of IL-2 in active AS patients significantly increase and will decrease after treatment.However,serum levels of IL- 11 significantly decrease and will increase after treatment,which indicates that serum IL-2 has a positive correlation with the degree of AS and serum IL-11 has a negative correlation with the degree of AS,both of which are correlated closely with the onset of AS.展开更多
The densification mechanism of an Fe-based alloy powder containing tiny oxide particles under the synergic multi-field effect of spark plasma sintering(SPS) was investigated. Metallographic microscopy and scanning ele...The densification mechanism of an Fe-based alloy powder containing tiny oxide particles under the synergic multi-field effect of spark plasma sintering(SPS) was investigated. Metallographic microscopy and scanning electron microscopy were used to observe the morphology of samples sintered at different temperatures, and the temperature distribution in an individual spherical powder particle during sintering was calculated in consideration of the influence of plasma, which was qualified and quantified through the analysis of the U-I curve. The plasma was observed to play a substantial role in activating and heating the samples at the very early stage of sintering, whereas the joule-heat effect played a dominant role during sintering. Moreover, the plasma also facilitated the diffusion and migration of materials for neck formation.展开更多
BACKGROUND Solitary necrotic nodule of the liver(SNNL)is a rare benign lesion with a complete necrotic core and a clear fibrous capsule containing elastic fibers.We present the case of a patient with a radiographic co...BACKGROUND Solitary necrotic nodule of the liver(SNNL)is a rare benign lesion with a complete necrotic core and a clear fibrous capsule containing elastic fibers.We present the case of a patient with a radiographic computed tomography(CT)finding of"ring"-like annular calcification within the lesion and postoperative pathologic diagnosis of necrotic nodules wrapped by dense fibers in liver tissue,as well as the patient's subsequent management and outcome.CASE SUMMARY A 38-year-old Chinese woman with a history of systemic lupus erythematosus treated with prednisone and hydroxychloroquine,without any symptoms,was found to have hepatic space-occupying lesions by imaging examination at a health examination.A subsequent CT scan suggested a space-occupying lesion of the liver with annular calcification,which was not defined to be benign or malignant.After that,a laparoscopic hepatic space-occupying resection was performed.The postoperative pathological diagnosis was necrotic nodules wrapped by dense fibers in the liver tissue,and the final diagnosis was SNNL.The patient had an uneventful postoperative recovery.CONCLUSION There is a"ring"-like calcification in SNNL.This patient had a history of systemic lupus erythematosus,without a history of parasite infection,trauma,or tumor.Therefore,whether the etiology and pathological changes of SNNL are related to rheumatic immune diseases remains to be investigated.展开更多
Owing to its high production costs, complexity of equipment, and difficulty in controlling parameters,spherical or subglobose tungsten powder preparation method cannot meet the demand of industrial production.Tungstic...Owing to its high production costs, complexity of equipment, and difficulty in controlling parameters,spherical or subglobose tungsten powder preparation method cannot meet the demand of industrial production.Tungstic oxide powder was treated by particle composite system and its effects were studied. Morphologies of particles were investigated by scanning electron microscopy(SEM). Particle size analysis was carried out and the related mechanism was discussed. The results show that the processing effect is best when the rotational speed is set at 4,000 r·min-1 for 15 min: the powder particles become nearly spherical and their sharp edge angles are rounded off and reshaped. When the processing time is 60min, the powders smash to pieces because of too much energy inputting. So the test results, such as grain size distribution,can be explained well. Nearly spherical tungsten powder is obtained after reduction at 780°C for 2h and its flow ability is significantly improved.展开更多
In this study,the effects of powder mixed method,sintering temperature,and the additive amount of the conductive phase on the dielectric loss tangent and permittivity constant of AlN/Mo composite ceramics were investi...In this study,the effects of powder mixed method,sintering temperature,and the additive amount of the conductive phase on the dielectric loss tangent and permittivity constant of AlN/Mo composite ceramics were investigated.All the ceramic samples were prepared by spark plasma sintering(SPS).AlN composite ceramics with additional 10 vol%Mo sintered at 1400℃holding for 5 min exhibit the best dielectric loss tangent,which is greater than 0.23.AlN/Mo ceramics with additional 20 vol%Mo become conductive,with the resistivity of 0.05–0.06Ω·m.High-energy ball milling is better than magnetic stirring powder mixing method.In addition,the additive Mo and lower sintering temperature lead to a better property with the increase in the electromagnetic wave frequency range of 1×10^(3)–1×10^(6)Hz.展开更多
Owing to contradiction between increasing demand of spherical tungsten powder and limitation of traditional manufacturing technology,a novel preparation method was developed to sphericize the polygonal tungsten powder...Owing to contradiction between increasing demand of spherical tungsten powder and limitation of traditional manufacturing technology,a novel preparation method was developed to sphericize the polygonal tungsten powder by means of modification of particle composite system.Tungsten powder particles were modified by par-ticle composite system,and detailed characterization by scanning electron microscopy(SEM)was studied.Particle size distribution and function mechanism were analyzed,and the internal relationship between average diameter and processing time was discussed.The results show that the spherical tungsten powder with an average diameter of 6.41μm is obtained from polyhedral tungsten powder with an average diameter of 7.50μm.The spherical effect could be achieved(sharp edge angles of particles are rounded off and reshaped)when the processing time is over 30 min.The relationship between average diameter(d)and pro-cessing time can be described by the exponential decay model,which provides a good interpretation for the process of modification.The relationship between them can be expressed by the equation d=1.87406exp(-x/8.92718)+6.4182.The proposed method could readily enable large-scale production of spherical tungsten powder.展开更多
基金financially supported by the International S&T Cooperation Program of China(No.2010DFR50360)
文摘In this study, we have investigated how the dielectric loss tangent and permittivity of AlN ceramics are affected by factors such as powder mixing methods, milling time, sintering temperature, and the addition of a second conductive phase. All ceramic samples were prepared by spark plasma sintering(SPS) under a pressure of 30 MPa. AlN composite ceramics sintered with 30wt%–40wt% SiC at 1600°C for 5 min exhibited the best dielectric loss tangent, which is greater than 0.3. In addition to AlN and β-SiC, the samples also contained 2H-SiC and Fe5Si3, as detected by X-ray difraction(XRD). The relative densities of the sintered ceramics were higher than 93%. Experimental results indicate that nano-SiC has a strong capability of absorbing electromagnetic waves. The dielectric constant and dielectric loss of AlN-SiC ceramics with the same content of SiC decreased as the frequency of electromagnetic waves increased from 1 kHz to 1 MHz.
文摘Objective:To explore the expression of IL-2 and IL-11 and its significance in patients with ankylosing spondylitis(AS).Methods:A total of 48 active AS patients in our hospital and 40 normal control subjects were selected in our study.Bath ankylosing spondylitis disease activity index(BASDAI),Bath ankylosing spondylitis functional index(BASFI),Bath ankylosing spondylitis metrology index(BASMI),ESR and CRP expression levels were compared before treatment,12 h after treatment and 24 h after treatment.IL-2 and IL-11 expression were also compared between these two groups.Results:The BASDAI score,BASH score and BASMI score of the AS patients before treatment significantly decreased compared with those 12 weeks and 24 weeks after treatment(P【0.05).ESB and CRP levels of the AS patients 12 weeks and 24 weeks after treatment significantly decreased compared with those before treatment(P【0.05).Difference was significant in serum IL-2 and IL-11 levels between 12 weeks and 24 weeks after treatment and before treatment(P【0.05).And no statistically significance was observed for serum IL-2 and IL-11 levels between normal control group and those of patients in AS group 24 weeks after treatment(P】0.05). Pearson’s linear-correlation analysis showed that serum IL-2 level had a positive correlation with BASDAI,BASFI,BASMI,ESR and CRP(r=0.661.0.547,0.474,0.362,0.416,P【0.05) and serum IL-11 level had a negative correlation with BASDAI,BASFI,BASMI,ESR and CRP(r=-0.629, -0.412,-0.422,-0.387,-0.408,-0.315,P【0.05).Conclusions:Serum levels of IL-2 in active AS patients significantly increase and will decrease after treatment.However,serum levels of IL- 11 significantly decrease and will increase after treatment,which indicates that serum IL-2 has a positive correlation with the degree of AS and serum IL-11 has a negative correlation with the degree of AS,both of which are correlated closely with the onset of AS.
基金financially supported by the Major State Basic Research Development Program of China (Nos. 2007CB209801 and 2011CB610400)
文摘The densification mechanism of an Fe-based alloy powder containing tiny oxide particles under the synergic multi-field effect of spark plasma sintering(SPS) was investigated. Metallographic microscopy and scanning electron microscopy were used to observe the morphology of samples sintered at different temperatures, and the temperature distribution in an individual spherical powder particle during sintering was calculated in consideration of the influence of plasma, which was qualified and quantified through the analysis of the U-I curve. The plasma was observed to play a substantial role in activating and heating the samples at the very early stage of sintering, whereas the joule-heat effect played a dominant role during sintering. Moreover, the plasma also facilitated the diffusion and migration of materials for neck formation.
文摘BACKGROUND Solitary necrotic nodule of the liver(SNNL)is a rare benign lesion with a complete necrotic core and a clear fibrous capsule containing elastic fibers.We present the case of a patient with a radiographic computed tomography(CT)finding of"ring"-like annular calcification within the lesion and postoperative pathologic diagnosis of necrotic nodules wrapped by dense fibers in liver tissue,as well as the patient's subsequent management and outcome.CASE SUMMARY A 38-year-old Chinese woman with a history of systemic lupus erythematosus treated with prednisone and hydroxychloroquine,without any symptoms,was found to have hepatic space-occupying lesions by imaging examination at a health examination.A subsequent CT scan suggested a space-occupying lesion of the liver with annular calcification,which was not defined to be benign or malignant.After that,a laparoscopic hepatic space-occupying resection was performed.The postoperative pathological diagnosis was necrotic nodules wrapped by dense fibers in the liver tissue,and the final diagnosis was SNNL.The patient had an uneventful postoperative recovery.CONCLUSION There is a"ring"-like calcification in SNNL.This patient had a history of systemic lupus erythematosus,without a history of parasite infection,trauma,or tumor.Therefore,whether the etiology and pathological changes of SNNL are related to rheumatic immune diseases remains to be investigated.
基金financially supported by the International Science and Technology Cooperation Program of China(No.2010DFR50360)
文摘Owing to its high production costs, complexity of equipment, and difficulty in controlling parameters,spherical or subglobose tungsten powder preparation method cannot meet the demand of industrial production.Tungstic oxide powder was treated by particle composite system and its effects were studied. Morphologies of particles were investigated by scanning electron microscopy(SEM). Particle size analysis was carried out and the related mechanism was discussed. The results show that the processing effect is best when the rotational speed is set at 4,000 r·min-1 for 15 min: the powder particles become nearly spherical and their sharp edge angles are rounded off and reshaped. When the processing time is 60min, the powders smash to pieces because of too much energy inputting. So the test results, such as grain size distribution,can be explained well. Nearly spherical tungsten powder is obtained after reduction at 780°C for 2h and its flow ability is significantly improved.
基金financially supported by the International Cooperation Project between China and Russia (No. 2010DFR50360)
文摘In this study,the effects of powder mixed method,sintering temperature,and the additive amount of the conductive phase on the dielectric loss tangent and permittivity constant of AlN/Mo composite ceramics were investigated.All the ceramic samples were prepared by spark plasma sintering(SPS).AlN composite ceramics with additional 10 vol%Mo sintered at 1400℃holding for 5 min exhibit the best dielectric loss tangent,which is greater than 0.23.AlN/Mo ceramics with additional 20 vol%Mo become conductive,with the resistivity of 0.05–0.06Ω·m.High-energy ball milling is better than magnetic stirring powder mixing method.In addition,the additive Mo and lower sintering temperature lead to a better property with the increase in the electromagnetic wave frequency range of 1×10^(3)–1×10^(6)Hz.
基金financially supported by the International Science and Technology Cooperation Program of China (No.2010DFR50360)
文摘Owing to contradiction between increasing demand of spherical tungsten powder and limitation of traditional manufacturing technology,a novel preparation method was developed to sphericize the polygonal tungsten powder by means of modification of particle composite system.Tungsten powder particles were modified by par-ticle composite system,and detailed characterization by scanning electron microscopy(SEM)was studied.Particle size distribution and function mechanism were analyzed,and the internal relationship between average diameter and processing time was discussed.The results show that the spherical tungsten powder with an average diameter of 6.41μm is obtained from polyhedral tungsten powder with an average diameter of 7.50μm.The spherical effect could be achieved(sharp edge angles of particles are rounded off and reshaped)when the processing time is over 30 min.The relationship between average diameter(d)and pro-cessing time can be described by the exponential decay model,which provides a good interpretation for the process of modification.The relationship between them can be expressed by the equation d=1.87406exp(-x/8.92718)+6.4182.The proposed method could readily enable large-scale production of spherical tungsten powder.
