The radiation of material surface by high intensity laser beams is used to produce the uhrafinepowder of pure Fe and ZrO<sub>2</sub>.The morphology,size and phases of the powder were examinedby X-ray diffr...The radiation of material surface by high intensity laser beams is used to produce the uhrafinepowder of pure Fe and ZrO<sub>2</sub>.The morphology,size and phases of the powder were examinedby X-ray diffraetometer,scanning electron microscopy as well as transmission electronmicroscopy.In pure Fe a considerable quantity of γ-phase was found in the powder.InZrO<sub>2</sub> powder,instead of stable phase,two metastable phases appeared.展开更多
The W-Co compound precursor powderswith an average particle size of 60 nm were prepared by thechemical coprecipitation as the raw materials of Na<sub>2</sub>WO<sub>4</sub> andCoCl<sub>2&l...The W-Co compound precursor powderswith an average particle size of 60 nm were prepared by thechemical coprecipitation as the raw materials of Na<sub>2</sub>WO<sub>4</sub> andCoCl<sub>2</sub> and as the reagents of HCl and NH<sub>3</sub>·H<sub>2</sub>O. After re-ducing and carburizing the precursor powders by hydrogengas and CO-Co<sub>2</sub> mixture gas, the WC-Co composite powderswith an Laverage particle size of 0.18μm can be obtained. Thepurity and particle size of powders were analysed by XRDand TEM. respectively. Meanwhile, the key .factors to influ-ence the reducing and carburizing process of powders werealso studied.展开更多
The hexagonal BaGd x Fe 12- x O 19 ( x =0.1～1.0) nano sized powders with M type structure were synthesized by the sol gel auto combustion high temperature synthesis method. The effects of pH of the solution, the mola...The hexagonal BaGd x Fe 12- x O 19 ( x =0.1～1.0) nano sized powders with M type structure were synthesized by the sol gel auto combustion high temperature synthesis method. The effects of pH of the solution, the molar ratio of nitrate/citric acid and the calcination temperature on the synthesis of the ferrites were investigated. The crystal structure, grain size, shape and magnetic properties were studied by means of XRD, TEM and vibrating sample magnetometer.The results show that under the conditions of pH 7.0 or so, mole ratio of citrate/nitrate (1～3) and calcination temperature of 850 ℃ for 1 h, M type BaGd x Fe 12- x O 19 ultrafine powders with a particle size of less than 100 nm can be obtained, and the coercive force reaches 430 kA·m -1 at x =1.0, which is far greater than that of barium ferrite (BaFe 12 O 19 ).展开更多
The precursor of ultrafine In 2O 3 powder was prepared by the hydrolysis, peptization and gelation of InCl 3·4H 2O used as raw material. After calcination, ultrafine In 2O 3 powder was obtained. The particles wer...The precursor of ultrafine In 2O 3 powder was prepared by the hydrolysis, peptization and gelation of InCl 3·4H 2O used as raw material. After calcination, ultrafine In 2O 3 powder was obtained. The particles were characterized by the methods of thermo gravimetric and differential thermal analysis (TG DTA), X ray diffractometry (XRD) and transmission electron microscopy (TEM), respectively.展开更多
A simple and rapid process for synthesizing lead zirconate titanate, Pb（Zr 0.52Ti 0.48）O3 （PZT）, ferroelectric powders was developed. This process, combining the sol-gel and combustion process, offers several adva...A simple and rapid process for synthesizing lead zirconate titanate, Pb（Zr 0.52Ti 0.48）O3 （PZT）, ferroelectric powders was developed. This process, combining the sol-gel and combustion process, offers several advantages over conventional methods, including rapid solution synthesis, use of commercially available materials, lower synthesis temperature and ease of obtaining ultrafine powders. The precursor solution for synthesizing powders was prepared from lead nitrate, zirconium nitrate, titanium oxynitrate, citric acid and deionized water. The precursor was investigated by DSC-TG, and the PZT powders were investigated by powder-XRD, IR spectra and TEM. XRD analysis shows that the powders possess a single-phase perovskite-type structure, no pyrochlore phase exists, and TEM image shows that the grain size of the powders is about 40nm.展开更多
The present study evaluated ef fects of ultrafine powder of the green macroalgae E nteromopha prolifera as dietary supplement on growth performance, digestive enzyme activities and serum nonspecific immune responses o...The present study evaluated ef fects of ultrafine powder of the green macroalgae E nteromopha prolifera as dietary supplement on growth performance, digestive enzyme activities and serum nonspecific immune responses of the red tilapia(O reochromis mossambicus × Oreochromis niloticus). The red tilapia were fed five diets supplemented with different levels of E. prolifera ultrafine powder as well as a control diet containing no E. prolifera for seven weeks(Diets 0–6 contained 0(control), 10, 20, 30, 40 and 50 g/kg of E. prolifera ultrafine powder, respectively). The results showed that diets supplemented with E. prolifera ultrafine powder generally improved growth, immunity and digestive enzyme activities of the red tilapia. In particular, the fish fed the diet incorporated 50 g/kg (5%) E. prolifera ultrafine powder(Diet 5) achieved the highest percentage weight gain, specific growth rate and the condition factor(increased by 15.4%, 8.0% and 5.7%, respectively when compared to the control). Feeding the diet also led to significantly increases( P <0.05) in serum nonspecific immune responses, including total superoxide dismutase, acid phosphatase, alkaline phosphatase, lysozyme activities and serum total protein(increased by 19.4%, 48.1%, 29.5%, 30.3% and 8.7%, respectively) as well as digestive enzyme activities of erepsin, gastric amylase, gastric lipase, pepsin, intestinal amylase and gastric lipase(increased by 15.7%, 33.3%, 16.3%, 21.3%, 52.3% and 28.2%, respectively) than those of the control. Based on these results, it is recommended that the inclusion level of E. prolifera ultrafine powder in the diet of the red tilapia should be 50 g/kg(or 5%).展开更多
The ultrafine powders of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> withthe size of 100nm were synthesized by Sol-Gel process using cit-rate as complex and ammonium hydroxide to a...The ultrafine powders of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> withthe size of 100nm were synthesized by Sol-Gel process using cit-rate as complex and ammonium hydroxide to adjust pH of solu-tion. The process of Sol formation and Gel polymerization ofYBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> in the Sol-Gel synthetic reaction has bee studied.The particle size,pruity,sintering activity and superconductingproperties of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub>prepared by Sol-Gel method are betterthan by solid state reaction.展开更多
Barium (Bag) ferrite ultra fine powders were synthesized by using sol-gel in which polyethylene glycol 200(PEG200) was used as gelling agent. The transition of Ba ferrite was studied by thermal gravimetric and differe...Barium (Bag) ferrite ultra fine powders were synthesized by using sol-gel in which polyethylene glycol 200(PEG200) was used as gelling agent. The transition of Ba ferrite was studied by thermal gravimetric and differential thermal analysis (TG-DTA) technology. The micro structural changes were analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM) for the specimens annealed at different temperatures. The transition temperatures were 414.55°C and separately corresponding to BaFe2O4 and BaFe,2O19. There were three types of microstructures for Ba ferrite ultrafine powder specimen annealed at 800°C. For the specimens annealed at different temperatures, there were different kinds of Ba ferrites. The ferrite powder consists of BaFet2O19 and BaFe2O4 for the specimen annealed at 800°C, and only BaFe^O^ can be found in the specimen annealed at 1000°C. The magnetic properties, a , and H c of BaFC|2O19 ultrafine powders are different from that of BaFe12O19 bulk material.展开更多
[Objective] This paper aimed to observe the effects of Qishen ultrafine powder on immune efficacy of infectious bursal disease vaccine in chickens.[Method] 360 1-day-old chickens were randomly divided into six groups ...[Objective] This paper aimed to observe the effects of Qishen ultrafine powder on immune efficacy of infectious bursal disease vaccine in chickens.[Method] 360 1-day-old chickens were randomly divided into six groups equally,and group I-V were vaccinated with IBD live virus vaccine on the 21st and 35th day,respectively.From 14th to 21st day,group I-III were added with 1%,0.5% of Qishen ultrafine powder and 2% of Qishen powder in basal diet,respectively,group IV was given Yupingfeng oral liquid and group VI was as a control group without vaccination.Before the experiment (14-day-old chickens as D0) and 7 (D7),14 (D14),21 (D21),28 (D28),35 (D35),42 (D42) days after the experiment,the dynamic change of serum IBD specific antibody was determined,respectively.On D7,D21 and D35,the dynamic change of peripheral T lymphocyte proliferation and IL-2 in serum were determined,respectively.The weight change was also observed.[Results] Compared with the immune control group,the immune effects of IBD vaccine of each administration group were significantly improved,and there was no significant difference between each other.[Conclusion] Qishen ultrafine powder could increase immune function of chickens at lower dosage.展开更多
The hexagonal BaNd x Fe 12- x O 19 ( x =0.1 1 0) fine powders with M type structure were synthesized by sol gel auto combustion high temperature synthesis method. The structure of powders, gels′ combustion and magnet...The hexagonal BaNd x Fe 12- x O 19 ( x =0.1 1 0) fine powders with M type structure were synthesized by sol gel auto combustion high temperature synthesis method. The structure of powders, gels′ combustion and magnetic properties of powders were respectively studied by means of X ray diffractometer (XRD), differential thermal analysis thermogravimetric analysis (DTA TG) and vibrating sample magnetometer (VSM). The powders before and after combustion and calcination at 450 850 ℃ with different mole ratio of Nd to Ba (0.1 1.0) were compared in terms of XRD. In addition, the effects of different synthesis conditions on magnetic properties of powders were also discussed. The results show that at pH 7.0 or so, mole ratio of citrate to nitrate (1 3) and calcination temperature of 850 ℃ for 1 h, M type BaNd x Fe 12- x O 19 ( x =0.1 1.0) fine powders can be obtained, and the coercive force reaches 436880 A·m -1 at x =1, which is far greater than that of barium permanent ferrite (BaFe 12 O 19 ).展开更多
In this study,ultrafine HfB_(2) powders with low oxygen were synthesized by a flocculating settling process which yielded ceramic precursors and subsequent carbo/borothermal reduction of the precursors.The liquid phas...In this study,ultrafine HfB_(2) powders with low oxygen were synthesized by a flocculating settling process which yielded ceramic precursors and subsequent carbo/borothermal reduction of the precursors.The liquid phase precursor method can achieve uniform mixing of components at the molecular level through multiple complexation reactions,and then realize the carbo/borothermal reduction reaction at a lower temperature to obtain ultrapure HfB2 powders.The as-resulted quasi-spherical HfB2 powders under the optimum conditions(atomic molar ratio M:B:C=1:2.8:10)calcined at 1500°C for 1 h have an average particle size of 205 nm and an oxygen content of 0.097 wt.%.Detailed analysis of the phase evolution of precursors shows that the formation of HfB2 particles is a mass diffusion mode from the external to internal HfO_(2)cores.We reveal that below 1300°C,HfC is not an intermediate product of HfB2 powder during the transition of precursors.Instead,HfC was formed as a by-product at high temperatures in the carbo/borothermal reduction process.The proposed formation mechanism of HfB_(2) is completely different from the traditional two-step transformation method.After the sintering of the ultrafine powders,the HfB_(2) ceramics show a relative density of 96.1%and superior mechanical properties compared to other works.Furthermore,by simply replacing the initial metal source,chlorinated group IV and V transitional metals(Ti,Zr,Ta,Nb)can also convert into high-purity and ultrafine diborides.This work shows that flocculating settling assisted carbo/borothermal reduction has potential in lot size production of various high-purity and ultrafine boride powders.展开更多
The effects of ultrafine WC(WC_(UF),0.5μm) or W(1μm) and C(0.3μm)(W+C)_(UF) additives on the densification,microstructure and mechanical properties of coarse-grained cemented carbides were compared systematically.O...The effects of ultrafine WC(WC_(UF),0.5μm) or W(1μm) and C(0.3μm)(W+C)_(UF) additives on the densification,microstructure and mechanical properties of coarse-grained cemented carbides were compared systematically.Overall,the cemented carbides with WC_(UF)/(W+C)_(UF) additives are almost fully densification to be higher than 99%,and the average grain size is kept above 2.8μm.The WC_(UF) additive assists grains to(truncated)trigonal prism shape by two dimensional(2D) growth,whereas the(W+C)_(UF) additive assists grains to rounded shape by three dimensional(3D) growth,lowers WC contiguity and increases face-centered-cubic Co.The hardness and bending strength of(75WC_(C)-15WC_(UF))-10Co are 86.6 HRA and 2 272 MPa,respectively,both higher than those of(75WC_(C)-15(W+C)_(UF))-10Co,which could be ascribed to the enhanced densification and unblemished grains.However,the fracture toughness of the(75WC_(C)-15(W+C)_(UF))-10Co is 23.5 MPa·m^(1/2),higher than that of the(75WC_(C)-15WC_(UF))-10Co due to the uniform WC-Co structure and flexible binder phase.展开更多
As an energetic material of great interest,the work capacity of dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate(TKX-50)has been questioned recently.Although some research groups have explored the reasons for the l...As an energetic material of great interest,the work capacity of dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate(TKX-50)has been questioned recently.Although some research groups have explored the reasons for the low working ability of TKX-50,the plane impact experiment on powdered TKX-50 is obviously closer to the practical application,and the conclusions based on this are more guiding.Hence,we performed shock Hugoniot measurements of powdered TKX-50 between 5.65 and 16.29 GPa.The plane impact experiments of powdered TKX-50 were carried out and the shocked Raman spectra were collected.By Raman spectroscopy analysis,a new peak of powdered TKX-50 was found between19.47 GPa and 24.96 GPa,which may be caused by decomposition/phase transition and was related with the low work capacity.展开更多
The practical engineering applications of powder metallurgy (PM) Ti alloys produced through cold compaction and pressure-less sintering are impeded by poor sintering densification, embrittlement caused by excessive O ...The practical engineering applications of powder metallurgy (PM) Ti alloys produced through cold compaction and pressure-less sintering are impeded by poor sintering densification, embrittlement caused by excessive O impurities, and severe sintering deforma-tion resulting from the use of heterogeneous powder mixtures. This review presents a summary of our previous work on addressing the above challenges. Initially, we proposed a novel strategy using reaction-induced liquid phases to enhance sintering densification. Near- complete density (relative density exceeding 99%) was achieved by applying the above strategy and newly developed sintering aids. By focusing on the O-induced embrittlement issue, we determined the onset dissolution temperature of oxide films in the Ti matrix. On the basis of this finding, we established a design criterion for effective O scavengers that require reaction with oxide films before their dissol-ution. Consequently, a ductile PM Ti alloy was successfully obtained by introducing 0.3wt% NdB6 as the O scavenger. Lastly, a powder- coating strategy was adopted to address the sintering deformation issue. The ultrafine size and shell-like distribution characteristics of coating particles ensured rapid dissolution and homogeneity in the Ti matrix, thereby facilitating linear shrinkage during sintering. As a result, geometrically complex Ti alloy parts with high dimensional accuracy were fabricated by using the coated powder. Our fundament-al findings and related technical achievements enabled the development of an integrated production technology for the high-performance and accurate shaping of low-cost PM Ti alloys. Additionally, the primary engineering applications and progress in the industrialization practice of our developed technology are introduced in this review.展开更多
Diarrhea has become the leading cause of illness and death among infants and young children in developing countries.Clinically,patients with diarrhea showed damaged intestinal epithelial villi,usually accompanied by l...Diarrhea has become the leading cause of illness and death among infants and young children in developing countries.Clinically,patients with diarrhea showed damaged intestinal epithelial villi,usually accompanied by lactase deficiency.In this study,we evaluated the therapeutic effects of lactose-free milk powder on rats and children with diarrhea.Antibiotic-associated diarrhea(AAD)model was established by gavage with antibiotic mixture in SD rats,followed by administration of milk powder containing lactose or not.The results showed that lactose-free milk powder ameliorated A AD-related diarrhea symptoms,and accelerated the recovery from diarrhea.And 16S sequencing results indicated lactose-free milk powder contributed to increase theα-andβ-diversity of intestinal flora,and restore the intestinal microbiota disorder.In conclusion,our data demonstrate that lactose-free milk powder could alleviate diarrhea by restoring gut microbiota and intestinal barrier function.展开更多
Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials(EMs)due to their obvious catalytic effect on the EMs,especially the uniformly dispersed nanomaterials.H...Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials(EMs)due to their obvious catalytic effect on the EMs,especially the uniformly dispersed nanomaterials.However,few studies have reported the dispersion of nanomaterials.In this study,the dispersity and mixing uniformity of nano-CuCr_(2)O_(4)was evaluated based on the difference of solid UV light absorption between the nano-catalytic materials and EMs.The nano-CuCr_(2)O_(4)/ultrafine AP composites with different dispersity of nano-CuCr_(2)O_(4)were prepared by manual grinding and mechanical grinding with different grinding strength and griding time.And then,the absorbance of different samples at 212 nm was obtained by solid UV testing due to the high repeatability of the absorbance at 210-214 nm for three parallel experiments,and the dispersity of different samples was calculated through the established difference equation.Furthermore,the samples were characterized by XRD,IR,SEM,EDS,DSC and TG-MS,which confirmed that different mixing methods did not change the structure of the samples(XRD and IR),and the mixing uniformity improved with the increase of grinding strength and grinding time(SEM and EDS).The scientificity and feasibility of the difference equation were further verified by DSC.The dispersity of nano-CuCr_(2)O_(4)exhibits a positive intrinsic relationship with its catalytic performance,and the uniformly dispersed nano-CuCr_(2)O_(4)significantly reduces the thermal decomposition temperature of ultrafine AP from 367.7 to 338.8℃.The TG-MS patterns show that the dispersed nano-CuCr_(2)O_(4)advanced the thermal decomposition process of ultrafine AP by about 700 s,especially in the high temperature decomposition stage,and the more concentrated energy release characteristic is beneficial to further enhance the energy performance of AP-based propellants.The above conclusions show that the evaluation method of dispersity based on solid UV curves could provide new ideas for the dispersity characterization of nano-catalytic materials in EMs,which is expected to be widely used in the field of EMs.展开更多
In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion ero...In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion erosion resistance.The results indicate that the influence of RFP on these three aspects is different.The carbonization depth after 30 days and the chloride diffusion coefficient of mortar containing 10%RFP decreased by 13.3%and 28.19%.With a further increase in the RFP content,interconnected pores formed between the RFP particles,leading to an acceleration of the penetration rate of CO_(2)and Cl^(−).When the RFP content was less than 50%,the corrosion resistance coefficient of the compressive strength of the mortar was 0.84-1.05 after 90 days of sulfate attack.But the expansion and cracking of the mortar was effectively alleviated due to decrease of the gypsum production.Scanning electron microscope(SEM)analysis has confirmed that 10%RFP contributes to the formation of a dense microstructure in the cement mortar.展开更多
Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-cond...Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel.Two interface configurations of M300 on CuCr1Zr and CuCr1Zr on M300 were investigated. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone.Regardless of these defects, the thermal diffusivity of bimetallic parts with 50vol% of CuCr1Zr significantly increases by 70%–150%compared to pure M300. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment.展开更多
Aiming at improving the properties of magnesia carbon materials,silicon aluminum carbide(Al_(4)SiC_(4))containing materials were prepared using industrial aluminum powder,silicon carbide powder,and graphite as raw mat...Aiming at improving the properties of magnesia carbon materials,silicon aluminum carbide(Al_(4)SiC_(4))containing materials were prepared using industrial aluminum powder,silicon carbide powder,and graphite as raw materials,and activated alumina powder as an additive,mixing thoroughly,pressing into cylinders and then firing at 1200℃for 30 min in a carbon embedded atmosphere by the microwave method.The effects of the aluminum powder addition(20%and 24%,by mass)and activated alumina powder addition(0,3%,5%and 7%,by mass)on the microwave synthesis of Al_(4)SiC_(4) as well as the effect of the obtained Al_(4)SiC_(4) containing material on the properties of magnesia carbon bricks were studied.The results show that:compared with the samples with 20%aluminum powder,those with 24%aluminum powder generate more Al_(4)SiC_(4).With the activated alumina powder addition increasing from 0 to 7%,the amount of Al_(4)SiC_(4) generated increases first and then decreases.Compared with the sample without activated alumina powder,the samples with activated alumina powder show lower bulk density and higher apparent porosity.With the activated alumina powder addition increasing from 3%to 7%,the bulk density of the samples increases first and then decreases,while the apparent porosity of the samples shows an opposite trend.The optimal additions are 24%aluminum powder and 5%activated alumina powder,and Al_(4)SiC_(4) synthesized in this sample has a hexagonal plate structure.With the synthesized Al_(4)SiC_(4) containing material added,the magnesia carbon brick has slightly increased cold modulus of rupture,basically the same modulus of elasticity and improved oxidation resistance.展开更多
文摘The radiation of material surface by high intensity laser beams is used to produce the uhrafinepowder of pure Fe and ZrO<sub>2</sub>.The morphology,size and phases of the powder were examinedby X-ray diffraetometer,scanning electron microscopy as well as transmission electronmicroscopy.In pure Fe a considerable quantity of γ-phase was found in the powder.InZrO<sub>2</sub> powder,instead of stable phase,two metastable phases appeared.
文摘The W-Co compound precursor powderswith an average particle size of 60 nm were prepared by thechemical coprecipitation as the raw materials of Na<sub>2</sub>WO<sub>4</sub> andCoCl<sub>2</sub> and as the reagents of HCl and NH<sub>3</sub>·H<sub>2</sub>O. After re-ducing and carburizing the precursor powders by hydrogengas and CO-Co<sub>2</sub> mixture gas, the WC-Co composite powderswith an Laverage particle size of 0.18μm can be obtained. Thepurity and particle size of powders were analysed by XRDand TEM. respectively. Meanwhile, the key .factors to influ-ence the reducing and carburizing process of powders werealso studied.
文摘The hexagonal BaGd x Fe 12- x O 19 ( x =0.1～1.0) nano sized powders with M type structure were synthesized by the sol gel auto combustion high temperature synthesis method. The effects of pH of the solution, the molar ratio of nitrate/citric acid and the calcination temperature on the synthesis of the ferrites were investigated. The crystal structure, grain size, shape and magnetic properties were studied by means of XRD, TEM and vibrating sample magnetometer.The results show that under the conditions of pH 7.0 or so, mole ratio of citrate/nitrate (1～3) and calcination temperature of 850 ℃ for 1 h, M type BaGd x Fe 12- x O 19 ultrafine powders with a particle size of less than 100 nm can be obtained, and the coercive force reaches 430 kA·m -1 at x =1.0, which is far greater than that of barium ferrite (BaFe 12 O 19 ).
文摘The precursor of ultrafine In 2O 3 powder was prepared by the hydrolysis, peptization and gelation of InCl 3·4H 2O used as raw material. After calcination, ultrafine In 2O 3 powder was obtained. The particles were characterized by the methods of thermo gravimetric and differential thermal analysis (TG DTA), X ray diffractometry (XRD) and transmission electron microscopy (TEM), respectively.
文摘A simple and rapid process for synthesizing lead zirconate titanate, Pb（Zr 0.52Ti 0.48）O3 （PZT）, ferroelectric powders was developed. This process, combining the sol-gel and combustion process, offers several advantages over conventional methods, including rapid solution synthesis, use of commercially available materials, lower synthesis temperature and ease of obtaining ultrafine powders. The precursor solution for synthesizing powders was prepared from lead nitrate, zirconium nitrate, titanium oxynitrate, citric acid and deionized water. The precursor was investigated by DSC-TG, and the PZT powders were investigated by powder-XRD, IR spectra and TEM. XRD analysis shows that the powders possess a single-phase perovskite-type structure, no pyrochlore phase exists, and TEM image shows that the grain size of the powders is about 40nm.
基金Supported by the Natural Science Foundation of Fujian Province(No.2017J01638)the Science and Technology Project Grant of Xiamen City,China(No.3502Z20113029)the Key Project of Technology Grant of Fujian Province(No.2012N0018)
文摘The present study evaluated ef fects of ultrafine powder of the green macroalgae E nteromopha prolifera as dietary supplement on growth performance, digestive enzyme activities and serum nonspecific immune responses of the red tilapia(O reochromis mossambicus × Oreochromis niloticus). The red tilapia were fed five diets supplemented with different levels of E. prolifera ultrafine powder as well as a control diet containing no E. prolifera for seven weeks(Diets 0–6 contained 0(control), 10, 20, 30, 40 and 50 g/kg of E. prolifera ultrafine powder, respectively). The results showed that diets supplemented with E. prolifera ultrafine powder generally improved growth, immunity and digestive enzyme activities of the red tilapia. In particular, the fish fed the diet incorporated 50 g/kg (5%) E. prolifera ultrafine powder(Diet 5) achieved the highest percentage weight gain, specific growth rate and the condition factor(increased by 15.4%, 8.0% and 5.7%, respectively when compared to the control). Feeding the diet also led to significantly increases( P <0.05) in serum nonspecific immune responses, including total superoxide dismutase, acid phosphatase, alkaline phosphatase, lysozyme activities and serum total protein(increased by 19.4%, 48.1%, 29.5%, 30.3% and 8.7%, respectively) as well as digestive enzyme activities of erepsin, gastric amylase, gastric lipase, pepsin, intestinal amylase and gastric lipase(increased by 15.7%, 33.3%, 16.3%, 21.3%, 52.3% and 28.2%, respectively) than those of the control. Based on these results, it is recommended that the inclusion level of E. prolifera ultrafine powder in the diet of the red tilapia should be 50 g/kg(or 5%).
文摘The ultrafine powders of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> withthe size of 100nm were synthesized by Sol-Gel process using cit-rate as complex and ammonium hydroxide to adjust pH of solu-tion. The process of Sol formation and Gel polymerization ofYBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> in the Sol-Gel synthetic reaction has bee studied.The particle size,pruity,sintering activity and superconductingproperties of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub>prepared by Sol-Gel method are betterthan by solid state reaction.
文摘Barium (Bag) ferrite ultra fine powders were synthesized by using sol-gel in which polyethylene glycol 200(PEG200) was used as gelling agent. The transition of Ba ferrite was studied by thermal gravimetric and differential thermal analysis (TG-DTA) technology. The micro structural changes were analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM) for the specimens annealed at different temperatures. The transition temperatures were 414.55°C and separately corresponding to BaFe2O4 and BaFe,2O19. There were three types of microstructures for Ba ferrite ultrafine powder specimen annealed at 800°C. For the specimens annealed at different temperatures, there were different kinds of Ba ferrites. The ferrite powder consists of BaFet2O19 and BaFe2O4 for the specimen annealed at 800°C, and only BaFe^O^ can be found in the specimen annealed at 1000°C. The magnetic properties, a , and H c of BaFC|2O19 ultrafine powders are different from that of BaFe12O19 bulk material.
基金funded by the Henan Provincial Key Scientific and Technological Project(122102110185)
文摘[Objective] This paper aimed to observe the effects of Qishen ultrafine powder on immune efficacy of infectious bursal disease vaccine in chickens.[Method] 360 1-day-old chickens were randomly divided into six groups equally,and group I-V were vaccinated with IBD live virus vaccine on the 21st and 35th day,respectively.From 14th to 21st day,group I-III were added with 1%,0.5% of Qishen ultrafine powder and 2% of Qishen powder in basal diet,respectively,group IV was given Yupingfeng oral liquid and group VI was as a control group without vaccination.Before the experiment (14-day-old chickens as D0) and 7 (D7),14 (D14),21 (D21),28 (D28),35 (D35),42 (D42) days after the experiment,the dynamic change of serum IBD specific antibody was determined,respectively.On D7,D21 and D35,the dynamic change of peripheral T lymphocyte proliferation and IL-2 in serum were determined,respectively.The weight change was also observed.[Results] Compared with the immune control group,the immune effects of IBD vaccine of each administration group were significantly improved,and there was no significant difference between each other.[Conclusion] Qishen ultrafine powder could increase immune function of chickens at lower dosage.
文摘The hexagonal BaNd x Fe 12- x O 19 ( x =0.1 1 0) fine powders with M type structure were synthesized by sol gel auto combustion high temperature synthesis method. The structure of powders, gels′ combustion and magnetic properties of powders were respectively studied by means of X ray diffractometer (XRD), differential thermal analysis thermogravimetric analysis (DTA TG) and vibrating sample magnetometer (VSM). The powders before and after combustion and calcination at 450 850 ℃ with different mole ratio of Nd to Ba (0.1 1.0) were compared in terms of XRD. In addition, the effects of different synthesis conditions on magnetic properties of powders were also discussed. The results show that at pH 7.0 or so, mole ratio of citrate to nitrate (1 3) and calcination temperature of 850 ℃ for 1 h, M type BaNd x Fe 12- x O 19 ( x =0.1 1.0) fine powders can be obtained, and the coercive force reaches 436880 A·m -1 at x =1, which is far greater than that of barium permanent ferrite (BaFe 12 O 19 ).
基金financially supported by the National Science Fund for Distinguished Young Scholars(No.51825103)the National Science Fund for Excellent Young Scholars(No.52222208)+1 种基金the Major science and technology project of Anhui Province(No.008192841048)the HFIPS Director's Fund,CAS(No.BJPY2021B04,YZJJ202202-CX,YZJJKX202202).
文摘In this study,ultrafine HfB_(2) powders with low oxygen were synthesized by a flocculating settling process which yielded ceramic precursors and subsequent carbo/borothermal reduction of the precursors.The liquid phase precursor method can achieve uniform mixing of components at the molecular level through multiple complexation reactions,and then realize the carbo/borothermal reduction reaction at a lower temperature to obtain ultrapure HfB2 powders.The as-resulted quasi-spherical HfB2 powders under the optimum conditions(atomic molar ratio M:B:C=1:2.8:10)calcined at 1500°C for 1 h have an average particle size of 205 nm and an oxygen content of 0.097 wt.%.Detailed analysis of the phase evolution of precursors shows that the formation of HfB2 particles is a mass diffusion mode from the external to internal HfO_(2)cores.We reveal that below 1300°C,HfC is not an intermediate product of HfB2 powder during the transition of precursors.Instead,HfC was formed as a by-product at high temperatures in the carbo/borothermal reduction process.The proposed formation mechanism of HfB_(2) is completely different from the traditional two-step transformation method.After the sintering of the ultrafine powders,the HfB_(2) ceramics show a relative density of 96.1%and superior mechanical properties compared to other works.Furthermore,by simply replacing the initial metal source,chlorinated group IV and V transitional metals(Ti,Zr,Ta,Nb)can also convert into high-purity and ultrafine diborides.This work shows that flocculating settling assisted carbo/borothermal reduction has potential in lot size production of various high-purity and ultrafine boride powders.
基金Funded by the Technology Innovation Leading Program of Shaanxi(No.2022QFY08-02)。
文摘The effects of ultrafine WC(WC_(UF),0.5μm) or W(1μm) and C(0.3μm)(W+C)_(UF) additives on the densification,microstructure and mechanical properties of coarse-grained cemented carbides were compared systematically.Overall,the cemented carbides with WC_(UF)/(W+C)_(UF) additives are almost fully densification to be higher than 99%,and the average grain size is kept above 2.8μm.The WC_(UF) additive assists grains to(truncated)trigonal prism shape by two dimensional(2D) growth,whereas the(W+C)_(UF) additive assists grains to rounded shape by three dimensional(3D) growth,lowers WC contiguity and increases face-centered-cubic Co.The hardness and bending strength of(75WC_(C)-15WC_(UF))-10Co are 86.6 HRA and 2 272 MPa,respectively,both higher than those of(75WC_(C)-15(W+C)_(UF))-10Co,which could be ascribed to the enhanced densification and unblemished grains.However,the fracture toughness of the(75WC_(C)-15(W+C)_(UF))-10Co is 23.5 MPa·m^(1/2),higher than that of the(75WC_(C)-15WC_(UF))-10Co due to the uniform WC-Co structure and flexible binder phase.
基金supported by the National Natural Science Foundation of China(Grant No.12072299)the Fundamental Research Funds for the Central Universities(Grant No.2682020ZT102)。
文摘As an energetic material of great interest,the work capacity of dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate(TKX-50)has been questioned recently.Although some research groups have explored the reasons for the low working ability of TKX-50,the plane impact experiment on powdered TKX-50 is obviously closer to the practical application,and the conclusions based on this are more guiding.Hence,we performed shock Hugoniot measurements of powdered TKX-50 between 5.65 and 16.29 GPa.The plane impact experiments of powdered TKX-50 were carried out and the shocked Raman spectra were collected.By Raman spectroscopy analysis,a new peak of powdered TKX-50 was found between19.47 GPa and 24.96 GPa,which may be caused by decomposition/phase transition and was related with the low work capacity.
基金supported by the National Natural Science Foundation of China (Nos.52074254 and 52174349)the CAS Project for Young Scientists in Basic Research,China (No.YSBR-025)+3 种基金the Shandong Provincial Science and Technology Innovation Project,China (No.2019JZZY010363)the Key Projects of International Cooperation,China (No.122111KYSB20200034)the Project of Key Laboratory of Science and Technology on Particle Materials,China (No.CXJJ-22S043)Chinese Academy of Sciences.This work was also financially supported by the Selection of Best Candidates to Undertake Key Research Projects,China (No.211110230200).
文摘The practical engineering applications of powder metallurgy (PM) Ti alloys produced through cold compaction and pressure-less sintering are impeded by poor sintering densification, embrittlement caused by excessive O impurities, and severe sintering deforma-tion resulting from the use of heterogeneous powder mixtures. This review presents a summary of our previous work on addressing the above challenges. Initially, we proposed a novel strategy using reaction-induced liquid phases to enhance sintering densification. Near- complete density (relative density exceeding 99%) was achieved by applying the above strategy and newly developed sintering aids. By focusing on the O-induced embrittlement issue, we determined the onset dissolution temperature of oxide films in the Ti matrix. On the basis of this finding, we established a design criterion for effective O scavengers that require reaction with oxide films before their dissol-ution. Consequently, a ductile PM Ti alloy was successfully obtained by introducing 0.3wt% NdB6 as the O scavenger. Lastly, a powder- coating strategy was adopted to address the sintering deformation issue. The ultrafine size and shell-like distribution characteristics of coating particles ensured rapid dissolution and homogeneity in the Ti matrix, thereby facilitating linear shrinkage during sintering. As a result, geometrically complex Ti alloy parts with high dimensional accuracy were fabricated by using the coated powder. Our fundament-al findings and related technical achievements enabled the development of an integrated production technology for the high-performance and accurate shaping of low-cost PM Ti alloys. Additionally, the primary engineering applications and progress in the industrialization practice of our developed technology are introduced in this review.
基金supported by the project of two children’s dairy products (201704810610483)。
文摘Diarrhea has become the leading cause of illness and death among infants and young children in developing countries.Clinically,patients with diarrhea showed damaged intestinal epithelial villi,usually accompanied by lactase deficiency.In this study,we evaluated the therapeutic effects of lactose-free milk powder on rats and children with diarrhea.Antibiotic-associated diarrhea(AAD)model was established by gavage with antibiotic mixture in SD rats,followed by administration of milk powder containing lactose or not.The results showed that lactose-free milk powder ameliorated A AD-related diarrhea symptoms,and accelerated the recovery from diarrhea.And 16S sequencing results indicated lactose-free milk powder contributed to increase theα-andβ-diversity of intestinal flora,and restore the intestinal microbiota disorder.In conclusion,our data demonstrate that lactose-free milk powder could alleviate diarrhea by restoring gut microbiota and intestinal barrier function.
基金the National Natural Science Foundation of China(Project Nos.21805139,21905023,12102194,22005144 and 22005145)the Joint Funds of the National Natural Science Foundation of China(Grant No.U2141202)+2 种基金Natural Science Foundation of Jiangsu Province(Grant No.BK20200471)the Fundamental Research Funds for the Central Universities(Grant Nos.30920041106,30921011203)Young Elite Scientists Sponsorship Program by CAST(Program,2021QNRC001).
文摘Improving the application of nanomaterials has always been a research hotspot in the field of energetic materials(EMs)due to their obvious catalytic effect on the EMs,especially the uniformly dispersed nanomaterials.However,few studies have reported the dispersion of nanomaterials.In this study,the dispersity and mixing uniformity of nano-CuCr_(2)O_(4)was evaluated based on the difference of solid UV light absorption between the nano-catalytic materials and EMs.The nano-CuCr_(2)O_(4)/ultrafine AP composites with different dispersity of nano-CuCr_(2)O_(4)were prepared by manual grinding and mechanical grinding with different grinding strength and griding time.And then,the absorbance of different samples at 212 nm was obtained by solid UV testing due to the high repeatability of the absorbance at 210-214 nm for three parallel experiments,and the dispersity of different samples was calculated through the established difference equation.Furthermore,the samples were characterized by XRD,IR,SEM,EDS,DSC and TG-MS,which confirmed that different mixing methods did not change the structure of the samples(XRD and IR),and the mixing uniformity improved with the increase of grinding strength and grinding time(SEM and EDS).The scientificity and feasibility of the difference equation were further verified by DSC.The dispersity of nano-CuCr_(2)O_(4)exhibits a positive intrinsic relationship with its catalytic performance,and the uniformly dispersed nano-CuCr_(2)O_(4)significantly reduces the thermal decomposition temperature of ultrafine AP from 367.7 to 338.8℃.The TG-MS patterns show that the dispersed nano-CuCr_(2)O_(4)advanced the thermal decomposition process of ultrafine AP by about 700 s,especially in the high temperature decomposition stage,and the more concentrated energy release characteristic is beneficial to further enhance the energy performance of AP-based propellants.The above conclusions show that the evaluation method of dispersity based on solid UV curves could provide new ideas for the dispersity characterization of nano-catalytic materials in EMs,which is expected to be widely used in the field of EMs.
基金This work is supported by the Zhuhai Science and Technology Project(ZH22036203200015PWC)the Open Foundation of State Key Laboratory of Subtropical Building Science(2022ZB20).
文摘In this paper,the durability of cement mortar prepared with a recycled-concrete fine powder(RFP)was examined;including the analysis of a variety of aspects,such as the carbonization,sulfate attack and chloride ion erosion resistance.The results indicate that the influence of RFP on these three aspects is different.The carbonization depth after 30 days and the chloride diffusion coefficient of mortar containing 10%RFP decreased by 13.3%and 28.19%.With a further increase in the RFP content,interconnected pores formed between the RFP particles,leading to an acceleration of the penetration rate of CO_(2)and Cl^(−).When the RFP content was less than 50%,the corrosion resistance coefficient of the compressive strength of the mortar was 0.84-1.05 after 90 days of sulfate attack.But the expansion and cracking of the mortar was effectively alleviated due to decrease of the gypsum production.Scanning electron microscope(SEM)analysis has confirmed that 10%RFP contributes to the formation of a dense microstructure in the cement mortar.
基金supported by VTT Technical Research Centre of Finland,Aalto University,Aerosint SA,and partially from European Union Horizon 2020 (No.768775)。
文摘Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel.Two interface configurations of M300 on CuCr1Zr and CuCr1Zr on M300 were investigated. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone.Regardless of these defects, the thermal diffusivity of bimetallic parts with 50vol% of CuCr1Zr significantly increases by 70%–150%compared to pure M300. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment.
基金This work was funded by Luoyang Major Science and Technology Innovation Project(2301009A)Henan Province Key ResearchandDevelopment Project(231111230200).
文摘Aiming at improving the properties of magnesia carbon materials,silicon aluminum carbide(Al_(4)SiC_(4))containing materials were prepared using industrial aluminum powder,silicon carbide powder,and graphite as raw materials,and activated alumina powder as an additive,mixing thoroughly,pressing into cylinders and then firing at 1200℃for 30 min in a carbon embedded atmosphere by the microwave method.The effects of the aluminum powder addition(20%and 24%,by mass)and activated alumina powder addition(0,3%,5%and 7%,by mass)on the microwave synthesis of Al_(4)SiC_(4) as well as the effect of the obtained Al_(4)SiC_(4) containing material on the properties of magnesia carbon bricks were studied.The results show that:compared with the samples with 20%aluminum powder,those with 24%aluminum powder generate more Al_(4)SiC_(4).With the activated alumina powder addition increasing from 0 to 7%,the amount of Al_(4)SiC_(4) generated increases first and then decreases.Compared with the sample without activated alumina powder,the samples with activated alumina powder show lower bulk density and higher apparent porosity.With the activated alumina powder addition increasing from 3%to 7%,the bulk density of the samples increases first and then decreases,while the apparent porosity of the samples shows an opposite trend.The optimal additions are 24%aluminum powder and 5%activated alumina powder,and Al_(4)SiC_(4) synthesized in this sample has a hexagonal plate structure.With the synthesized Al_(4)SiC_(4) containing material added,the magnesia carbon brick has slightly increased cold modulus of rupture,basically the same modulus of elasticity and improved oxidation resistance.
