BACKGROUND Hepatocellular carcinoma(HCC)is one of the most frequent cancers and the main cause of cancer-related death worldwide.Ectopic HCC,an extremely rare type of HCC,exhibits a wide range of clinical signs and ra...BACKGROUND Hepatocellular carcinoma(HCC)is one of the most frequent cancers and the main cause of cancer-related death worldwide.Ectopic HCC,an extremely rare type of HCC,exhibits a wide range of clinical signs and radiographic features,making preoperative identification challenging.CASE SUMMARY A 47-year-old man underwent routine abdominal color ultrasonography,which identified an asymptomatic tumor in the left upper abdomen.The patient had no history of hepatitis,did not drink alcohol,and had no family history of cancer.Abdominal contrast-enhanced computed tomography(CT)revealed a heterogeneously enhanced lesion between the spleen and stomach that had invaded the diaphragm,with blood supplied by the left inferior phrenic artery.The patient underwent laparoscopic surgery,and HCC was identified by postoperative pathology.Additionally,specific immunohistochemical staining was performed to assess the molecular biological characteristics of the HCC.The patient underwent two rounds of hepatic arterial interventional chemotherapy after surgery.Abdominal plain and enhanced magnetic resonance imaging and lung CT 3 mo postoperatively revealed no signs of local recurrence or distant metastasis.CONCLUSION This asymptomatic ectopic HCC case described achieved an excellent result due to early detection,radical resection,and systematic surveillance.展开更多
Using steel slag as a main raw material of ceramics is considered as a high value-added way. However, the relationship among the initial composition, ceramic microstructure, and macroscopic properties requires further...Using steel slag as a main raw material of ceramics is considered as a high value-added way. However, the relationship among the initial composition, ceramic microstructure, and macroscopic properties requires further study. In this paper, a series of ceramics with different slag ratios (0-70wt%) were designed, and the software FACTsage was introduced to simulate the formation of crystalline phases. The simulation results indicate that mullite is generated but drastically reduced at the slag ratios of 0-25wt%, and anorthite is the dominant crystalline phase in the slag content of 25wt%-45wt%. When the slag ratio is above 45wt%, pyroxene is generated more than anorthite. This is because increasing magnesium can promote the formation of pyroxene. Then, the formula with a slag content of 40wt% was selected and optimized. X-ray diffraction results were good consistent with the simulation results. Finally, the water absorption and bending strength of optimized samples were measured.展开更多
In the 20CrMnTi steel production process, the nitrogen content increased by 19 × 10^-6 and 29 × 10^-6, respectively, during ladle furnace(LF) refining and during the casting process from ladle to tundish. ...In the 20CrMnTi steel production process, the nitrogen content increased by 19 × 10^-6 and 29 × 10^-6, respectively, during ladle furnace(LF) refining and during the casting process from ladle to tundish. The protective casting is the key to decrease the N content. The results of thermodynamic calculations and a growth kinetics investigation show that TiN formation occurs only when the solidification fraction is greater than 0.533 under the controlled conditions used in this study for the manufacture of 20CrMnTi steel; the radius of TiN particles decreases as the Ti and N contents decrease and as the cooling rate increases. Furthermore, the theory of austenite grains controlled by second-phase particles was analyzed. The elemental analysis results showed that the Ti content was controlled at 0.04wt%–0.06wt% and the N content decreased to 0.005wt%, which satisfy the requirements for grain refinement but can also effectively prevent the precipitation of TiN inclusions in 20CrMnTi steel.展开更多
For ultra-low-carbon(ULC)steel production,the higher oxygen content before Ruhrstahl-Heraeus(RH)decarburization(de-C)treatment could shorten the de-C time in the RH degasser.However,this would lead to oxidation rates ...For ultra-low-carbon(ULC)steel production,the higher oxygen content before Ruhrstahl-Heraeus(RH)decarburization(de-C)treatment could shorten the de-C time in the RH degasser.However,this would lead to oxidation rates being exceeded by molten steel production,affecting ULC steel surface quality.In this work,a carbon powder addition(CPA)process was proposed to reduce the dissolved oxygen content at the end of RH de-C through addition of carbon powder to molten steel in the vacuum vessel.Carbon and oxygen behavior during the CPA and conventional process was then studied.The results demonstrated that the de-C rate with CPA was lower compared to the conventional process,but the carbon content at the end of de-C presented no difference.The de-C reaction for CPA process took place in the four reaction sites:(1)within the bulk steel where the spontaneous CO bubbles form;(2)splashing area on the liquid steel surface;(3)Ar bubble surface;(4)molten steel surface.The CPA process could significantly reduce the dissolved oxygen content at the end of de-C,the sum content of FeO and MnO in the slag,the aluminum consumption,and the defect rate of rolled products.This was beneficial in improving ULC steel cleanliness.展开更多
A high Nb containing TiA1 alloy was prepared from the pre-alloyed powder of Ti-45Al-8.5Nb-0.2B-0.2W-0.02Y (at%) by spark plasma sintering (SPS). Its high-temperature mechanical properties and compressive deformati...A high Nb containing TiA1 alloy was prepared from the pre-alloyed powder of Ti-45Al-8.5Nb-0.2B-0.2W-0.02Y (at%) by spark plasma sintering (SPS). Its high-temperature mechanical properties and compressive deformation behavior were investigated in a temperature range of 700 to 1050℃ and a strain rate range of 0.002 to 0.2 s 1. The results show that the high-temperature mechanical properties of the high Nb containing TiA1 alloy are sensitive to deformation temperature and strain rate, and the sensitivity to strain rate tends to rise with the deformation temperature increasing. The hot workability of the alloy is good at temperatures higher than 900℃, while fracture occurs at lower temperatures. The flow curves of the samples compressed at or above 900℃ exhibit obvious flow softening after the peak stress. Un- der the deformation condition of 900-1050℃ and 0.002-0.2 s 1, the interrelations of peak flow stress, strain rate, and deformation tempera- ture follow the Arrhenius' equation modified by a hyperbolic sine function with a stress exponent of 5.99 and an apparent activation energy of 441.2 kJ.mol-1.展开更多
Two types of porcelain tiles with steel slag as the main raw material (steel slag ceramics) were synthesized based on the CaO-A1203-SiO2 and CaO--MgO-SiO2 systems, and their bending strengths up to 53.47 MPa and 99....Two types of porcelain tiles with steel slag as the main raw material (steel slag ceramics) were synthesized based on the CaO-A1203-SiO2 and CaO--MgO-SiO2 systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite, a-quartz, magnetite, and pyroxene crystals (augite and diopside) in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction (XRD) and electron probe X-ray microanalysis (EPMA) results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.展开更多
Low residual-free-oxygen before fmal de-oxidation was beneficial to improving the cleanness of ultra-low-carbon steel. For ultra-low-carbon steel production, the coordinated control of carbon and oxygen is a precondit...Low residual-free-oxygen before fmal de-oxidation was beneficial to improving the cleanness of ultra-low-carbon steel. For ultra-low-carbon steel production, the coordinated control of carbon and oxygen is a precondition for achieving low residual oxygen during the Ruhrstahl Heraeus (RH) decarburization process. In this work, we studied the coordinated control of carbon and oxygen for ultra-low-carbon steel during the basic oxygen furnace (BOF) endpoint and RH process using data statistics, multiple linear regressions, and thermodynamics computations. The results showed that the aluminum yield decreased linearly with increasing residual oxygen in liquid steel. When the mass ratio of free oxygen and carbon ([O]/[C]) in liquid steel before RH decarburization was maintained between 1.5 and 2.0 and the carbon range was from 0.030wt% to 0.040wt%, the residual oxygen after RH natural decarburization was low and easily controlled. To satisfy the requirement for RH decarburization, the carbon and free oxygen at the BOF endpoint should be controlled to be between 297 × 10^6 and 400 × 10^-6 and between 574 × 10^-6 and 775 × 10^-6, respectively, with a temperature of 1695 to 1715℃ and a furnace campaign of 1000 to 5000 heats.展开更多
Ferric oxide is one of the key factors affecting both the microstructure and the properties of CaO-MgO-SiO2-based ceramics. Research on this effect is significant in the utilization of iron-rich solid wastes in cerami...Ferric oxide is one of the key factors affecting both the microstructure and the properties of CaO-MgO-SiO2-based ceramics. Research on this effect is significant in the utilization of iron-rich solid wastes in ceramics. Ceramic samples with various Fe2O3 contents(0 wt%, 5 wt%, and 10 wt%) were prepared and the corresponding physical properties and microstructure were studied. The results indicated that Fe2O3 not only played a fluxing role, but also promoted the formation of crystals. Ceramics with 5 wt% of Fe2O3 addition attained the best mechanical properties with a flexural strength of 132.9 MPa. Iron ions were dissolved into diopside, consequently causing phase transformation from diopside and protoenstatite to augite, thereby contributing to the enhancement of its properties. An excess amount of Fe2O3 addition(10 wt% or more) resulted in deteriorated properties due to the generation of an excess volume of liquid and the formation of high-porosity structures within ceramics.展开更多
The strategy that replacing part of MnS with BN was proposed in order to decrease the sulfur content in sulfur based free-cutting steel. The effects of BN and MnS inclusions on the microstructure and machinability of ...The strategy that replacing part of MnS with BN was proposed in order to decrease the sulfur content in sulfur based free-cutting steel. The effects of BN and MnS inclusions on the microstructure and machinability of the steel were systematically investigated. The results show that most of the BN and MnS inclusions exist individually in the steel and only a small amount of them are in a composite state form- ing either isolated particles or clusters of particles. In the case of multi-phased steel, the theoretical calculation predicts that the volume of large BN particles should be 0.7 times of the volume of large MnS particles. The machinability of this type of BN and MnS alloy steel over a wide range of cutting speeds ranging from a low speed appropriate for drilling to a high speed appropriate for turning is confirmed as being equal to or superior to that of an MnS reference steel, even though the sulfur content in the composite steel is only half that of the MnS steel. The aptitude for cutting effect of 240 ppm nitrogen and 115 ppm boron in the composite steel is demonstrated to be equivalent or even better than 1000 ppm sulfur in MnS free-cutting steel.展开更多
Though light conditions are known to affect the development and anti-predation strategies of several aquatic species, relatively little is known about how different species react to light, or how light can affect thes...Though light conditions are known to affect the development and anti-predation strategies of several aquatic species, relatively little is known about how different species react to light, or how light can affect these species during different points in their life-cycle. In this study, we used four sympatric anuran tadpoles (Bufo gargarizans, B. melanostictus, Pelophylax nigromaculatus and Microhyla fissipes) as animal system to examine species-specific activities of the underdoing different light intensity treatments, so as to better understand how they respond to light. We exposed four different species of tadpoles to 1660 and 14 lux light intensity treatments and then measured several parameters including development stage, body length and tail length, and as well as their basic activities. The results of this observation and analysis showed that the activities of tadpoles were significantly greater in B. gargarizans and B. melanostictus than in P. nigromaculatus and M. fissipes; and were also significantly greater during times of high light intensity as compared to during low light intensity. Moreover, the observed relationship between species and light intensity was significant. The activities ofB. gargarizans and B. melanostictus tadpoles were greater in high light, while the activity of P. nigromaculatus tadpoles was greater in low light intensity, while M. fissipes tadpoles showed no differences in either low or high intensity light. Furthermore, the activities orB. gargarizans, B. melanostictus and M. fissipes tadpoles in terms of developmental stage, body size or tail length did not seem to differ with light intensity, but during early larval developmental period of P. nigromaculatus, the activity of tadpoles was negatively correlated with development stage, but irrelevant to either body size or tail length in different light intensities. These results lead us to conclude the observed activities of the four sympatric anuran tadpoles are closely correlated with their specific anti-predation strategies.展开更多
To obtain advanced quality pure copper, the microstructure of solidified copper was optimized by imposing electric pulse on liquid copper in this study. Experiments were performed to determine the effect of electric p...To obtain advanced quality pure copper, the microstructure of solidified copper was optimized by imposing electric pulse on liquid copper in this study. Experiments were performed to determine the effect of electric pulse voltage, arrangement mode of electrodes, and energy input on the microstructure of solidified copper. The results show that, when the energy input of electric pulse is bigger than 28.95 kJ per ton copper, the percent of fine grains increases noticeably with the increase of energy input; but when the energy input of electric pulse is smaller than 28.95 kJ per ton copper, the percent of fine grains decreases with the increase of energy input. The influence order of above factors on grain refinement is electric pulse voltage 〉 arrangement mode of electrodes 〉 energy input. According to the above experimental results, the optimum process conditions are chosen as the voltage being 400 V and the energy input greater than 28.95 kJ per ton copper. Meanwhile, the best arrangement mode of electrodes should be that, one electrode is immerged in the middle of liquid copper in the crystallizer, and the other is connected to the inner wall of the crystallizer, which is divided into two electrode poles for the symmetrical electric field distribution.展开更多
Aiming at the problem of negative segregation under a bloom surface, a coupling macrosegregation model considering electromagnetic field, flow, heat, and solute transport was established based on the volume average me...Aiming at the problem of negative segregation under a bloom surface, a coupling macrosegregation model considering electromagnetic field, flow, heat, and solute transport was established based on the volume average method to study the effect of in-mold electromagnetic stirring(M-EMS) on the negative segregation under the bloom surface. In the model, the influence of dendrite structure on the flow and solute transport was described by the change of permeability. The model was validated by the magnetic induction intensity of M-EMS and carbon segregation experiment. The results show that the solute C in the solidified shell in the turbulent zone of the bloom undergoes two negative segregations, whereby the first is caused by nozzle jet, and the second by the M-EMS. The severities of the negative segregation caused by M-EMS at different currents and frequencies are also different, and the larger the current is, or the smaller the frequency is, the more serious will be the negative segregation.With the M-EMS, the solute C distribution in the liquid phase of the bloom is more uniform, but the mass fraction of C in the liquid phase is higher than that without M-EMS.展开更多
An antifungal protein was isolated from a culture of Bacillus subtilis strain B29. The isolation procedure comprised ion exchange chromatography on diethylaminoethyl (DEAE)-52 cellulose and gel filtration chromatogr...An antifungal protein was isolated from a culture of Bacillus subtilis strain B29. The isolation procedure comprised ion exchange chromatography on diethylaminoethyl (DEAE)-52 cellulose and gel filtration chromatography on Bio-Gel P-100. The protein was absorbed on DEAE-cellulose and Bio-Gel P-100. The purified antifungal fraction was designated as B29I, with a molecular mass of 42.3 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), pl value 5.69 by isoelectric focusing (IEF)-PAGE, and 97.81% purity by high performance liquid chromatography (HPLC). B291 exhibited inhibitory activity on mycelial growth in Fusarium oxysporum, Rhizoctonia solani, Fusarium moniliforme, and Sclerotinia sclerotiorum. The 50% inhibitory concentrations (IC50) of its antifungal activity toward Fusarium oxysporum and Rhizoctonia solani were 45 and 112 μmol/L, respectively. B29I also demonstrated an inhibitory effect on conidial spore germination of Fusariurn oxysporum and suppression of germ-tube elongation, and induced distortion, tumescence, and rupture of a portion of the germinated spores.展开更多
Nonreciprocal devices are indispensable for building quantum networks and ubiquitous in modern communication technology.Here, we study perfect optical nonreciprocity in a three-mode optomechanical system with mechanic...Nonreciprocal devices are indispensable for building quantum networks and ubiquitous in modern communication technology.Here, we study perfect optical nonreciprocity in a three-mode optomechanical system with mechanical driving.The scheme relies on the interference between optomechanical interaction and mechanical driving.We find perfect optical nonreciprocity can be achieved even though nonreciprocal phase difference is zero if we drive the system by a mechanical driving with a nonzero phase.We obtain the essential conditions for perfect optical nonreciprocity and analyze properties of the optical nonreciprocal transmission.These results can be used to control optical transmission in quantum information processing.展开更多
文摘BACKGROUND Hepatocellular carcinoma(HCC)is one of the most frequent cancers and the main cause of cancer-related death worldwide.Ectopic HCC,an extremely rare type of HCC,exhibits a wide range of clinical signs and radiographic features,making preoperative identification challenging.CASE SUMMARY A 47-year-old man underwent routine abdominal color ultrasonography,which identified an asymptomatic tumor in the left upper abdomen.The patient had no history of hepatitis,did not drink alcohol,and had no family history of cancer.Abdominal contrast-enhanced computed tomography(CT)revealed a heterogeneously enhanced lesion between the spleen and stomach that had invaded the diaphragm,with blood supplied by the left inferior phrenic artery.The patient underwent laparoscopic surgery,and HCC was identified by postoperative pathology.Additionally,specific immunohistochemical staining was performed to assess the molecular biological characteristics of the HCC.The patient underwent two rounds of hepatic arterial interventional chemotherapy after surgery.Abdominal plain and enhanced magnetic resonance imaging and lung CT 3 mo postoperatively revealed no signs of local recurrence or distant metastasis.CONCLUSION This asymptomatic ectopic HCC case described achieved an excellent result due to early detection,radical resection,and systematic surveillance.
基金financially supported by the National Natural Science Foundation of China (Nos. 51034008 and 51004012)the National High Technology Research and Development Program of China (No. 2011AA06A105)
文摘Using steel slag as a main raw material of ceramics is considered as a high value-added way. However, the relationship among the initial composition, ceramic microstructure, and macroscopic properties requires further study. In this paper, a series of ceramics with different slag ratios (0-70wt%) were designed, and the software FACTsage was introduced to simulate the formation of crystalline phases. The simulation results indicate that mullite is generated but drastically reduced at the slag ratios of 0-25wt%, and anorthite is the dominant crystalline phase in the slag content of 25wt%-45wt%. When the slag ratio is above 45wt%, pyroxene is generated more than anorthite. This is because increasing magnesium can promote the formation of pyroxene. Then, the formula with a slag content of 40wt% was selected and optimized. X-ray diffraction results were good consistent with the simulation results. Finally, the water absorption and bending strength of optimized samples were measured.
基金supported by the National Natural Science Foundation of China (No. 51274029)
文摘In the 20CrMnTi steel production process, the nitrogen content increased by 19 × 10^-6 and 29 × 10^-6, respectively, during ladle furnace(LF) refining and during the casting process from ladle to tundish. The protective casting is the key to decrease the N content. The results of thermodynamic calculations and a growth kinetics investigation show that TiN formation occurs only when the solidification fraction is greater than 0.533 under the controlled conditions used in this study for the manufacture of 20CrMnTi steel; the radius of TiN particles decreases as the Ti and N contents decrease and as the cooling rate increases. Furthermore, the theory of austenite grains controlled by second-phase particles was analyzed. The elemental analysis results showed that the Ti content was controlled at 0.04wt%–0.06wt% and the N content decreased to 0.005wt%, which satisfy the requirements for grain refinement but can also effectively prevent the precipitation of TiN inclusions in 20CrMnTi steel.
基金financially supported by the National Natural Science Foundation of China(No.51874021)Fundamental Research Funds for the Central Universities of China(No.FRF-IC-18-002)State Key Laboratory of Advanced Metallurgy Foundation of China(No.41618019)
文摘For ultra-low-carbon(ULC)steel production,the higher oxygen content before Ruhrstahl-Heraeus(RH)decarburization(de-C)treatment could shorten the de-C time in the RH degasser.However,this would lead to oxidation rates being exceeded by molten steel production,affecting ULC steel surface quality.In this work,a carbon powder addition(CPA)process was proposed to reduce the dissolved oxygen content at the end of RH de-C through addition of carbon powder to molten steel in the vacuum vessel.Carbon and oxygen behavior during the CPA and conventional process was then studied.The results demonstrated that the de-C rate with CPA was lower compared to the conventional process,but the carbon content at the end of de-C presented no difference.The de-C reaction for CPA process took place in the four reaction sites:(1)within the bulk steel where the spontaneous CO bubbles form;(2)splashing area on the liquid steel surface;(3)Ar bubble surface;(4)molten steel surface.The CPA process could significantly reduce the dissolved oxygen content at the end of de-C,the sum content of FeO and MnO in the slag,the aluminum consumption,and the defect rate of rolled products.This was beneficial in improving ULC steel cleanliness.
基金supported by the National Natural Science Foundation of China (No.50974017)Research Fund for the Doctoral Program of Higher Education of China (No.20110006120023)
文摘A high Nb containing TiA1 alloy was prepared from the pre-alloyed powder of Ti-45Al-8.5Nb-0.2B-0.2W-0.02Y (at%) by spark plasma sintering (SPS). Its high-temperature mechanical properties and compressive deformation behavior were investigated in a temperature range of 700 to 1050℃ and a strain rate range of 0.002 to 0.2 s 1. The results show that the high-temperature mechanical properties of the high Nb containing TiA1 alloy are sensitive to deformation temperature and strain rate, and the sensitivity to strain rate tends to rise with the deformation temperature increasing. The hot workability of the alloy is good at temperatures higher than 900℃, while fracture occurs at lower temperatures. The flow curves of the samples compressed at or above 900℃ exhibit obvious flow softening after the peak stress. Un- der the deformation condition of 900-1050℃ and 0.002-0.2 s 1, the interrelations of peak flow stress, strain rate, and deformation tempera- ture follow the Arrhenius' equation modified by a hyperbolic sine function with a stress exponent of 5.99 and an apparent activation energy of 441.2 kJ.mol-1.
文摘Two types of porcelain tiles with steel slag as the main raw material (steel slag ceramics) were synthesized based on the CaO-A1203-SiO2 and CaO--MgO-SiO2 systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite, a-quartz, magnetite, and pyroxene crystals (augite and diopside) in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction (XRD) and electron probe X-ray microanalysis (EPMA) results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.
基金financially supported by the State Key Laboratory of Advanced Metallurgy Foundation in China (No. KF13-09)the National Natural Science Foundation of China (No. 51404018)+1 种基金the Fundamental Research Funds for the Central Universities (No. FRF-TP-14-125A2)the Doctoral Fund of the Ministry of Education of China (No. 20130006110023)
文摘Low residual-free-oxygen before fmal de-oxidation was beneficial to improving the cleanness of ultra-low-carbon steel. For ultra-low-carbon steel production, the coordinated control of carbon and oxygen is a precondition for achieving low residual oxygen during the Ruhrstahl Heraeus (RH) decarburization process. In this work, we studied the coordinated control of carbon and oxygen for ultra-low-carbon steel during the basic oxygen furnace (BOF) endpoint and RH process using data statistics, multiple linear regressions, and thermodynamics computations. The results showed that the aluminum yield decreased linearly with increasing residual oxygen in liquid steel. When the mass ratio of free oxygen and carbon ([O]/[C]) in liquid steel before RH decarburization was maintained between 1.5 and 2.0 and the carbon range was from 0.030wt% to 0.040wt%, the residual oxygen after RH natural decarburization was low and easily controlled. To satisfy the requirement for RH decarburization, the carbon and free oxygen at the BOF endpoint should be controlled to be between 297 × 10^6 and 400 × 10^-6 and between 574 × 10^-6 and 775 × 10^-6, respectively, with a temperature of 1695 to 1715℃ and a furnace campaign of 1000 to 5000 heats.
基金financially supported by the National Natural Science Foundation of China (No. 51474027)
文摘Ferric oxide is one of the key factors affecting both the microstructure and the properties of CaO-MgO-SiO2-based ceramics. Research on this effect is significant in the utilization of iron-rich solid wastes in ceramics. Ceramic samples with various Fe2O3 contents(0 wt%, 5 wt%, and 10 wt%) were prepared and the corresponding physical properties and microstructure were studied. The results indicated that Fe2O3 not only played a fluxing role, but also promoted the formation of crystals. Ceramics with 5 wt% of Fe2O3 addition attained the best mechanical properties with a flexural strength of 132.9 MPa. Iron ions were dissolved into diopside, consequently causing phase transformation from diopside and protoenstatite to augite, thereby contributing to the enhancement of its properties. An excess amount of Fe2O3 addition(10 wt% or more) resulted in deteriorated properties due to the generation of an excess volume of liquid and the formation of high-porosity structures within ceramics.
基金financially supported by the National Natural Science Foundation of China(No.51274029)the China Postdoctoral Science Foundation(No.2012M 510319)the State Key Laboratory of Advanced Metallurgy Foundation(No.41602014)
文摘The strategy that replacing part of MnS with BN was proposed in order to decrease the sulfur content in sulfur based free-cutting steel. The effects of BN and MnS inclusions on the microstructure and machinability of the steel were systematically investigated. The results show that most of the BN and MnS inclusions exist individually in the steel and only a small amount of them are in a composite state form- ing either isolated particles or clusters of particles. In the case of multi-phased steel, the theoretical calculation predicts that the volume of large BN particles should be 0.7 times of the volume of large MnS particles. The machinability of this type of BN and MnS alloy steel over a wide range of cutting speeds ranging from a low speed appropriate for drilling to a high speed appropriate for turning is confirmed as being equal to or superior to that of an MnS reference steel, even though the sulfur content in the composite steel is only half that of the MnS steel. The aptitude for cutting effect of 240 ppm nitrogen and 115 ppm boron in the composite steel is demonstrated to be equivalent or even better than 1000 ppm sulfur in MnS free-cutting steel.
基金supported by the National Natural Science Foundation of China(30970435,31270443)the Zhejiang Provincial National Science Foundation of China(C030403)+1 种基金the Open Research Fund program of Laboratory of Lishui University(2014-26-10)the Scientific Research Foundation of Ph.D.in Lishui University(QD1301)
文摘Though light conditions are known to affect the development and anti-predation strategies of several aquatic species, relatively little is known about how different species react to light, or how light can affect these species during different points in their life-cycle. In this study, we used four sympatric anuran tadpoles (Bufo gargarizans, B. melanostictus, Pelophylax nigromaculatus and Microhyla fissipes) as animal system to examine species-specific activities of the underdoing different light intensity treatments, so as to better understand how they respond to light. We exposed four different species of tadpoles to 1660 and 14 lux light intensity treatments and then measured several parameters including development stage, body length and tail length, and as well as their basic activities. The results of this observation and analysis showed that the activities of tadpoles were significantly greater in B. gargarizans and B. melanostictus than in P. nigromaculatus and M. fissipes; and were also significantly greater during times of high light intensity as compared to during low light intensity. Moreover, the observed relationship between species and light intensity was significant. The activities ofB. gargarizans and B. melanostictus tadpoles were greater in high light, while the activity of P. nigromaculatus tadpoles was greater in low light intensity, while M. fissipes tadpoles showed no differences in either low or high intensity light. Furthermore, the activities orB. gargarizans, B. melanostictus and M. fissipes tadpoles in terms of developmental stage, body size or tail length did not seem to differ with light intensity, but during early larval developmental period of P. nigromaculatus, the activity of tadpoles was negatively correlated with development stage, but irrelevant to either body size or tail length in different light intensities. These results lead us to conclude the observed activities of the four sympatric anuran tadpoles are closely correlated with their specific anti-predation strategies.
文摘To obtain advanced quality pure copper, the microstructure of solidified copper was optimized by imposing electric pulse on liquid copper in this study. Experiments were performed to determine the effect of electric pulse voltage, arrangement mode of electrodes, and energy input on the microstructure of solidified copper. The results show that, when the energy input of electric pulse is bigger than 28.95 kJ per ton copper, the percent of fine grains increases noticeably with the increase of energy input; but when the energy input of electric pulse is smaller than 28.95 kJ per ton copper, the percent of fine grains decreases with the increase of energy input. The influence order of above factors on grain refinement is electric pulse voltage 〉 arrangement mode of electrodes 〉 energy input. According to the above experimental results, the optimum process conditions are chosen as the voltage being 400 V and the energy input greater than 28.95 kJ per ton copper. Meanwhile, the best arrangement mode of electrodes should be that, one electrode is immerged in the middle of liquid copper in the crystallizer, and the other is connected to the inner wall of the crystallizer, which is divided into two electrode poles for the symmetrical electric field distribution.
基金financially supported by the National Natural Science Foundation of China(No.51774031)the Foundation of State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing,China(No.41602014)
文摘Aiming at the problem of negative segregation under a bloom surface, a coupling macrosegregation model considering electromagnetic field, flow, heat, and solute transport was established based on the volume average method to study the effect of in-mold electromagnetic stirring(M-EMS) on the negative segregation under the bloom surface. In the model, the influence of dendrite structure on the flow and solute transport was described by the change of permeability. The model was validated by the magnetic induction intensity of M-EMS and carbon segregation experiment. The results show that the solute C in the solidified shell in the turbulent zone of the bloom undergoes two negative segregations, whereby the first is caused by nozzle jet, and the second by the M-EMS. The severities of the negative segregation caused by M-EMS at different currents and frequencies are also different, and the larger the current is, or the smaller the frequency is, the more serious will be the negative segregation.With the M-EMS, the solute C distribution in the liquid phase of the bloom is more uniform, but the mass fraction of C in the liquid phase is higher than that without M-EMS.
基金supported by the Hi-Tech Research and Development Pro-gram (863) of China (No. 2003AA241140)the Natural Science Foundation of Heilongjiang Province, China (No. C200522)
文摘An antifungal protein was isolated from a culture of Bacillus subtilis strain B29. The isolation procedure comprised ion exchange chromatography on diethylaminoethyl (DEAE)-52 cellulose and gel filtration chromatography on Bio-Gel P-100. The protein was absorbed on DEAE-cellulose and Bio-Gel P-100. The purified antifungal fraction was designated as B29I, with a molecular mass of 42.3 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), pl value 5.69 by isoelectric focusing (IEF)-PAGE, and 97.81% purity by high performance liquid chromatography (HPLC). B291 exhibited inhibitory activity on mycelial growth in Fusarium oxysporum, Rhizoctonia solani, Fusarium moniliforme, and Sclerotinia sclerotiorum. The 50% inhibitory concentrations (IC50) of its antifungal activity toward Fusarium oxysporum and Rhizoctonia solani were 45 and 112 μmol/L, respectively. B29I also demonstrated an inhibitory effect on conidial spore germination of Fusariurn oxysporum and suppression of germ-tube elongation, and induced distortion, tumescence, and rupture of a portion of the germinated spores.
基金Supported by the National Natural Science Foundation of China under Grant Nos.41472126,11847018Natural Science Foundation of Guangxi Province under Grant No.2018GXNSFBA281003+1 种基金Starting Research Fund from the Guangxi Normal University(2017BQ022)Northeast Petroleum University Youth Foundation(NEPUQN2015–1–16)
文摘Nonreciprocal devices are indispensable for building quantum networks and ubiquitous in modern communication technology.Here, we study perfect optical nonreciprocity in a three-mode optomechanical system with mechanical driving.The scheme relies on the interference between optomechanical interaction and mechanical driving.We find perfect optical nonreciprocity can be achieved even though nonreciprocal phase difference is zero if we drive the system by a mechanical driving with a nonzero phase.We obtain the essential conditions for perfect optical nonreciprocity and analyze properties of the optical nonreciprocal transmission.These results can be used to control optical transmission in quantum information processing.