[Objective] The aim was to research and identify starch grain microfossil found in archaeological sites in China, and to find appropriate procedures for the starch grain analysis experiment.[Method] Wheat starch grain...[Objective] The aim was to research and identify starch grain microfossil found in archaeological sites in China, and to find appropriate procedures for the starch grain analysis experiment.[Method] Wheat starch grain size distribution was analyzed, and some simulated experiments were carried out, like mortar grinding, ultrasonic treatment, hydrochloric acid and hydrogen peroxide immersion, drying treatment, and so on. [Result] The mean size of wheat starch grains had increased in the growth process. Mortar grinding would make wheat starch grains larger than untreated sample. Long time of ultrasonic treatment can also make the starch grain size larger. 10% HCl and 6% H2O2 would have little effects on morphological feature of wheat starch grains. Low temperature heating did not cause starch grains to be gelatinized. [Conclusion] These experiment results can improve the accuracy of starch grain microfossil identification in the archaeological site. Starch grain analysis may be a utility and effective analytical tool in studying the origin of agriculture and the dispersal of crops in China.展开更多
The granular structure, crystal structure and gelatinization temp. of thermoplastic starch were studied with a polarized light microscope and a scanning electron microscope, and the crystallinity and crystalline patte...The granular structure, crystal structure and gelatinization temp. of thermoplastic starch were studied with a polarized light microscope and a scanning electron microscope, and the crystallinity and crystalline patterns were determined through X ray diffraction. The results indicate that the original granular structure and spherical crystalline structure of starch were disrupted by the action of pressure, heat and shear force with the help of additives. The starch can be melted during extrusion, and part of the spheric crystal was destroyed and changed into a continual amorphous with a few crystalline fractions dispersed in it. The configuration of starch molecules changed from double helices to single helix, which indicated the formation of the complex.展开更多
A self-developed double-nozzle gas atomization technique was used to produce AlSi10Mg powder.Effects of delivery tube diameter,gas pressure,and melt superheat on powder characteristics were investigated.The concepts o...A self-developed double-nozzle gas atomization technique was used to produce AlSi10Mg powder.Effects of delivery tube diameter,gas pressure,and melt superheat on powder characteristics were investigated.The concepts of bluntness and outgrowth were introduced to analyze powder sphericity and satellite index quantitatively.The results showed that the median diameters of all atomized powders ranged from 25 to 33μm.The highest yield rate(72.13%)of fine powder(<50μm)was obtained at a superheat of 350 K.The powder size decreased with increasing melt superheat but increased with increasing delivery tube diameter.Powders with bluntness values between 96%and 98%accounted for over 60%.The outgrowth values demonstrated that 70%-85%of all powders did not contain satellite particles,with few powders adhered two or three particles.Not only Al and Si phases were present but also a metastable Al9Si phase was detected.展开更多
Fluidization characteristics of silicon particle system are studied by the pressure fluctuation method.The existence of fine particles in the system can improve fluidization. Silicon particles with a wide size distrib...Fluidization characteristics of silicon particle system are studied by the pressure fluctuation method.The existence of fine particles in the system can improve fluidization. Silicon particles with a wide size distribution,preferably with some fines, behave as Group A particles according to Geldart classification, although the system belongs to Group B actually. The system is also approved to be suitable for organochlorosilane monomer production using a fluidized bed reactor. Experimental data obtained in this work are important for the design and operation of commercial fluidized bed reactors for the production of organochlorosilane monomers.展开更多
Ti-6 Al-4 V alloy powder was processed by electrode induction melting gas atomization(EIGA)at high gas pressure(5.5-7.0 MPa).The effects of atomizing gas pressure on the powder characteristics and the microstructure,a...Ti-6 Al-4 V alloy powder was processed by electrode induction melting gas atomization(EIGA)at high gas pressure(5.5-7.0 MPa).The effects of atomizing gas pressure on the powder characteristics and the microstructure,along with the mechanical properties of the as-fabricated block by laser melting deposition(LMD),were investigated.The results indicate that the diameters of powders are distributed in a wide range of sizes from 1 to 400μm,and the median powder size(d50)decreases with increasing gas pressure.The powders with a size fraction of 100-150μm obtained at gas pressures of 6.0 and 6.5 MPa have better flowability.The oxygen content is consistent with the change trend of gas pressure within a low range of 0.06%-0.20%.Specimens fabricated by LMD are mainly composed ofα+βgrains with a fine lamellar Widmanstatten structures and have the ultimate tensile strength(UTS)and yield strength of approximately 1100 and 1000 MPa,respectively.Furthermore,the atomized powders have a favorable 3 D printing capability,and the mechanical properties of Ti-6 Al-4 V alloys manufactured by LMD typically exceed those of their cast or wrought counterparts.展开更多
The airborne pollen grains of Afyon have been studied for a two_year period (1999-2000) with a Durham sampler. A total of 14 367 pollen grains belonging to 40 taxa have been identified and recorded with some unidentif...The airborne pollen grains of Afyon have been studied for a two_year period (1999-2000) with a Durham sampler. A total of 14 367 pollen grains belonging to 40 taxa have been identified and recorded with some unidentified ones. Of them, 6 732 were identified in 1999 and 7 635 in 2000. Of the total pollen grains, 69.67% were arboreal, 26.64% non_arboreal and 3.68 % unidentified. The majority of the investigated pollen grains were from Pinus, Gramineae, Cupressaceae, Platanus , Chenopodiaceae/Amaranthaceae, Quercus, Ailanthus, Moraceae, Juglans , Salix, Cedrus and Rosaceae. The highest level of pollen grains was in May.展开更多
Magnetic starch particles (MSPs) were synthesized in water-in-oil mieroemulsion at room temperature. MSPs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FTI...Magnetic starch particles (MSPs) were synthesized in water-in-oil mieroemulsion at room temperature. MSPs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FTIR), zeta potential system, thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM). The average diameter of the MSPs was 220 nm, dispersed with well-proportioned size and magnetic resonance, the saturation magnetization was 3.64 A.mR/kg. MSP was coated with poly-L-lysine (PLL), and then the surface of PLL-MSP was combined with fluorescein isothiocynate (FITC). Results show that fluorescent/magnetic starch particles (FMSPs) are of stable photo-bleaching capability compared with free FITC, with low bio-toxicity and certain function of magnetic separation. It is expected that FMSPs are bifimctional nano-materials including fluorescence labelling and magnetic separation.展开更多
A new combined desulfurization/denitration (DeSOx/DeNOx,) process was tested in this study. The process uses the so-called powder-particle fluidized bed (PPFB) as the major reactor in which a coarse DeNOx catalyst, se...A new combined desulfurization/denitration (DeSOx/DeNOx,) process was tested in this study. The process uses the so-called powder-particle fluidized bed (PPFB) as the major reactor in which a coarse DeNOx catalyst, several hundred micrometers in size, is fluidized by flue gas as the fluidization medium particles, while a continuously supplied fine DeSOx sorbent, several to tens of micrometers in diameter, is entrained with the flue gas. Ammonia for NOx reduction is fed to the bottom of the bed, thus, SOX and NOX are simultaneously removed in the single reactor. By adopting a model gas, SO2-NO-H2O-N2-air, to simulate actual flue gas in a laboratory-scale PPFB, simultaneous SO2 and NO removals were explored with respect to various gas components of flue gas. It was found that the variations of SO2 removal with concentrations (fractions) of oxygen, water vapor, SO2 and NO in flue gas are little affected by the simultaneous NOx reduction. However, the dependencies of NO removal upon such gas components are closely related to the inter-actions between DeSOx sorbent and DeNOx catalyst.展开更多
Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flak...Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.展开更多
Raw corn starch granules were hydrolysized by glucoamylase in a chemostat. The hydro- lysis of three different-sized granules shows that smaller granules undergo more hydrolyzation than larger ones. After 78 h, 9700 o...Raw corn starch granules were hydrolysized by glucoamylase in a chemostat. The hydro- lysis of three different-sized granules shows that smaller granules undergo more hydrolyzation than larger ones. After 78 h, 9700 of the granules was hydrolysized with diameter between 0.15 mm and 0.3 mm at 50 ℃. When corn starch concentration increased from 100 g/L to 250 g/L, the amount of reducing sugar produced was proportional to the initial substrate concentration and no substrate inhibition phenomenon appeared. In order to study the product inhibition exactly, the product from hydrolysis reaction itself was added into the hydrolysis system at the beginning of starch hydrolysis. Product inhibition with different quantities of product added were studied in the initial several hours, during which period enzyme inactivation could be neglected and product inhibition could be studied separately. The experiments indicate that product inhibition happens when the additional quantity exceeds 9.56 g/L.展开更多
Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the ...Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the roasting performance of pellets. In this work, high pressure roll grinding(HPRG) process and optimization of temperature elevation system were investigated to improve the strength of fired manganese ore pellets. It is shown that the manganese ore possesses good ballability after being pretreated by HPRG twice, and good green balls were produced under the conditions of blending 2.0% bentonite in the feed, balling for 7 min at 16.00% moisture. High quality roasted pellets with the compressive strength of 2711 N per pellet were manufactured through preheating at 1050 °C for 10 min and firing at 1335 °C for 15 min by controlling the cracks formation. The fired manganese pellets keep the strength by the solid interconnection of recrystallized pyrolusite grains and the binding of manganite liquid phase which filled the pores and clearance among minerals. The product pellets contain high Mn grade and low impurities, and can be used to smelt ferromanganese, which provides a possible way to use imported manganese ore fines containing high combined water to produce high value ferromanganese.展开更多
This study was carried out to investigate the possibility of titanium alloy metal powder production using low-power plasma torches.An argon DC non-transferred arc plasma torch was designed,and numerical analysis was c...This study was carried out to investigate the possibility of titanium alloy metal powder production using low-power plasma torches.An argon DC non-transferred arc plasma torch was designed,and numerical analysis was conducted to determine the plasma jet properties and wire temperature.The highest velocities inside the nozzle attachment were between 838 and 1178 m/s.The velocities of the jets at the apex were between 494 and 645 m/s for different gas flow rates.The studied plasma gas flow rates had no significant effect on the effective plasma jet length.It was shown that the plasma jet length can be estimated by numerical analysis using the temperature and velocity changes of the plasma jet over distance.It was observed that the powders produced were spherical without any satellites.As a result of this study,a plasma torch was developed and powder production was performed successfully by using relatively low torch power.展开更多
Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagati...Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.展开更多
Soft magnetic composites (SMCs) were prepared from three different ferromagnetic powder particles: iron powder ASC 100.29, spherical FeSi particles and vitroperm (Fe73CulNb3Si16B7) flakes. Two types of hybrid org...Soft magnetic composites (SMCs) were prepared from three different ferromagnetic powder particles: iron powder ASC 100.29, spherical FeSi particles and vitroperm (Fe73CulNb3Si16B7) flakes. Two types of hybrid organic-inorganic phenolic resins modified with either silica nanoparticles or boron were used to design a thin insulating layer perfect- ly covering the ferromagnetic particles. Fourier transform infrared (FTIR) spectrometry confirmed an incorporation of silica or boron into the polymer matrix, which manifested itself through an improved thermal stability of the hybrid resins verified by thermogravimetric-differential scanning calorimetry (TG-DSC) analysis. The core-shell particles prepared from the ferromagnetic powder particles and the modified hybrid resins were further compacted to the cylindrical and toroidal shapes for the mechanical, electrical and magnetic testing. A uniform distribution of the resin between the ferromagnetic particles was evidenced by scanning electron microscope (SEM) analysis, which was also reflected in a rather high value of the electrical resistivity. A low porosity and extraordinary high values of mechanical hardness and flexural strength were found in SMC consisting of the iron powder and phenolic resin modified with boron. The coercive fields of the prepared samples were comparable with the commercial SMCs.展开更多
This paper discussed impact of temperature on the size distribution in preparing ultrafine silica from rice husk.The samples prepared were analyzed with infrared spectrum,and the relation between the particle size and...This paper discussed impact of temperature on the size distribution in preparing ultrafine silica from rice husk.The samples prepared were analyzed with infrared spectrum,and the relation between the particle size and intensity of characteristic absorption peak of IR at center around 1 100 cm-1 was disscussed with the baseline method.Results show that when the temperature is 650 ℃ and roasting time is 11 h,at optimal reaction conditions,the size distribution of the ultrafine silica powder prepared is relatively concentrated,and the average particle size is 199.5 nm.Moreover,the characteristic absorption band of IR is broadening gradually along with particle size decreasing.展开更多
The effect of ground granulated blast-furnace slag(GGBFS) and silica fume(SF) on the chloride migration through concrete subjected to repeated loading was examined.Portland cement was replaced by 20%,30%,40% GGBFS and...The effect of ground granulated blast-furnace slag(GGBFS) and silica fume(SF) on the chloride migration through concrete subjected to repeated loading was examined.Portland cement was replaced by 20%,30%,40% GGBFS and 5%,10% SF,respectively.Five times repeated loadings were applied to specimens,the maximum loadings were 40% and 80% of the axial cylinder compressive strength(f′c),respectively.Chloride migration through concretes was evaluated using the rapid chloride migration test and the chloride concentration in the anode chamber was measured.The results indicate that the transport number of chloride through concrete containing 20% and 30% GGBFS replacements and 5% and 10% SF replacements is lower than that of the control concrete,but 40% GGBFS replacement increases the transport number of chloride.Five loadings at 40% f′cor 80% f′c increase the transport number of chloride for all mixes investigated in this study.5% SF replacement has a very close effect on the chloride permeability of concrete with 20% GGBFS when concrete is subjected to 40% f′cor 80% f′c.展开更多
Nanocarbon as an eco-friendly and abundant material has strong multi-color fluorescence, which makes it a promising candidate for healthy lighting and display. However, the low fluorescence efficiency and poor stabili...Nanocarbon as an eco-friendly and abundant material has strong multi-color fluorescence, which makes it a promising candidate for healthy lighting and display. However, the low fluorescence efficiency and poor stability of multi-color carbon nanoparticle(CNP) phosphors are main hurdles that hinder their applications. This work demonstrated efficient and stable multi-color CNP phosphors through synergy between inner polar groups and outer silica matrix. The polar groups in polyethylene glycol(PEG) 6,000 are favor of high fluorescence of the CNP phosphors, and the low melting point(64℃) of PEG 6,000 helps to improve the thermal stability of the phosphors, while the silica matrix provides protection to the phosphors. Based on this design,blue, green, yellow and red CNP phosphors with photoluminescence quantum yield of 53.1%, 47.4%, 43.8% and 42.3% have been achieved, all of which are the best values in ever reported multi-color CNP phosphors. Furthermore, the fluorescence of the CNP phosphors keeps almost unchanged at 100℃ and degrades little in one month, indicating their good thermal tolerance and temporal stability. In addition, multicolor devices including white light-emitting devices(LEDs)have been realized by coating the CNP phosphors onto UV chips. The luminous efficiency, correlated color temperature,Commission Internationale de L'Eclairage and color rendering index of the white LED can reach 12 lm W^-1, 6,107 K,(0.32, 0.33) and 89, respectively, indicating the potential applications of the CNP phosphors in lighting and display.展开更多
Low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O nanopowders(NPs)would determine their practical application in purifying wastewater.In this contribution,ZnO NPs were scala...Low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O nanopowders(NPs)would determine their practical application in purifying wastewater.In this contribution,ZnO NPs were scalably synthesized via the simple reaction of Zn powder with H_2O vapor in autoclave.The structural,morphological and optical properties of the samples were systematically characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectra,transmission electron microscopy,Micro-Raman,photoluminescence,and ultraviolet-visible spectroscopy.The as-prepared Zn O NPs are composed of nanoparticles with 100–150 nm in diameter,and have a small Brunauer-Emmett-Teller surface area of 6.85 m^2/g.The formation of Zn O nanoparticles is relative to the peeling of H_2 release.Furthermore,the product has big strain-stress leading to the red-shift in the band gap of product,and shows a strong green emission centered at 515 nm revealing enough atomic defects in Zn O NPs.As a comparison with P25,the obtained dust gray Zn O NPs have a strong absorbance in the region of 200–700 nm,suggesting the wide wave-band utilization in sunlight.Based on the traits above,the Zn O NPs show excellent photocatalytic activity on the degradation of rhodamine B(Rh-B)under solar light irradiation,close to that under UV irradiation.Importantly,the Zn O NPs could be well recycled in water due to the quick sedimentation in themselves in solution.The low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O NPs endow themselves with promising application in purifying wastewater.展开更多
基金Supported by National Natural Science Foundation of China(41072140)Chinese Academy of Sciences Strategic Priority Research Program(XDA05130402,XDA05130603)~~
文摘[Objective] The aim was to research and identify starch grain microfossil found in archaeological sites in China, and to find appropriate procedures for the starch grain analysis experiment.[Method] Wheat starch grain size distribution was analyzed, and some simulated experiments were carried out, like mortar grinding, ultrasonic treatment, hydrochloric acid and hydrogen peroxide immersion, drying treatment, and so on. [Result] The mean size of wheat starch grains had increased in the growth process. Mortar grinding would make wheat starch grains larger than untreated sample. Long time of ultrasonic treatment can also make the starch grain size larger. 10% HCl and 6% H2O2 would have little effects on morphological feature of wheat starch grains. Low temperature heating did not cause starch grains to be gelatinized. [Conclusion] These experiment results can improve the accuracy of starch grain microfossil identification in the archaeological site. Starch grain analysis may be a utility and effective analytical tool in studying the origin of agriculture and the dispersal of crops in China.
文摘The granular structure, crystal structure and gelatinization temp. of thermoplastic starch were studied with a polarized light microscope and a scanning electron microscope, and the crystallinity and crystalline patterns were determined through X ray diffraction. The results indicate that the original granular structure and spherical crystalline structure of starch were disrupted by the action of pressure, heat and shear force with the help of additives. The starch can be melted during extrusion, and part of the spheric crystal was destroyed and changed into a continual amorphous with a few crystalline fractions dispersed in it. The configuration of starch molecules changed from double helices to single helix, which indicated the formation of the complex.
基金Project(51627805) supported by the National Natural Science Foundation of ChinaProject(2015A030312003) supported by the Natural Science Foundation of Guangdong Province,China+1 种基金Projects(2014B010129003,2015B020238008,2016B090931006,2017B090901025) supported by the Science and Technology Research Department of Guangdong Province,ChinaProject(201604016049) supported by the Science and Technology Bureau of Guangzhou City,China
文摘A self-developed double-nozzle gas atomization technique was used to produce AlSi10Mg powder.Effects of delivery tube diameter,gas pressure,and melt superheat on powder characteristics were investigated.The concepts of bluntness and outgrowth were introduced to analyze powder sphericity and satellite index quantitatively.The results showed that the median diameters of all atomized powders ranged from 25 to 33μm.The highest yield rate(72.13%)of fine powder(<50μm)was obtained at a superheat of 350 K.The powder size decreased with increasing melt superheat but increased with increasing delivery tube diameter.Powders with bluntness values between 96%and 98%accounted for over 60%.The outgrowth values demonstrated that 70%-85%of all powders did not contain satellite particles,with few powders adhered two or three particles.Not only Al and Si phases were present but also a metastable Al9Si phase was detected.
文摘Fluidization characteristics of silicon particle system are studied by the pressure fluctuation method.The existence of fine particles in the system can improve fluidization. Silicon particles with a wide size distribution,preferably with some fines, behave as Group A particles according to Geldart classification, although the system belongs to Group B actually. The system is also approved to be suitable for organochlorosilane monomer production using a fluidized bed reactor. Experimental data obtained in this work are important for the design and operation of commercial fluidized bed reactors for the production of organochlorosilane monomers.
基金Project(2017YFB0305801)supported by the National Key R&D Program of ChinaProject(U1508213)supported by the Joint-Fund of NSFC-Liaoning,ChinaProject(51771051)supported by the National Natural Science Foundation of China.
文摘Ti-6 Al-4 V alloy powder was processed by electrode induction melting gas atomization(EIGA)at high gas pressure(5.5-7.0 MPa).The effects of atomizing gas pressure on the powder characteristics and the microstructure,along with the mechanical properties of the as-fabricated block by laser melting deposition(LMD),were investigated.The results indicate that the diameters of powders are distributed in a wide range of sizes from 1 to 400μm,and the median powder size(d50)decreases with increasing gas pressure.The powders with a size fraction of 100-150μm obtained at gas pressures of 6.0 and 6.5 MPa have better flowability.The oxygen content is consistent with the change trend of gas pressure within a low range of 0.06%-0.20%.Specimens fabricated by LMD are mainly composed ofα+βgrains with a fine lamellar Widmanstatten structures and have the ultimate tensile strength(UTS)and yield strength of approximately 1100 and 1000 MPa,respectively.Furthermore,the atomized powders have a favorable 3 D printing capability,and the mechanical properties of Ti-6 Al-4 V alloys manufactured by LMD typically exceed those of their cast or wrought counterparts.
文摘The airborne pollen grains of Afyon have been studied for a two_year period (1999-2000) with a Durham sampler. A total of 14 367 pollen grains belonging to 40 taxa have been identified and recorded with some unidentified ones. Of them, 6 732 were identified in 1999 and 7 635 in 2000. Of the total pollen grains, 69.67% were arboreal, 26.64% non_arboreal and 3.68 % unidentified. The majority of the investigated pollen grains were from Pinus, Gramineae, Cupressaceae, Platanus , Chenopodiaceae/Amaranthaceae, Quercus, Ailanthus, Moraceae, Juglans , Salix, Cedrus and Rosaceae. The highest level of pollen grains was in May.
基金Project(200501) supported by the "985" Program of China
文摘Magnetic starch particles (MSPs) were synthesized in water-in-oil mieroemulsion at room temperature. MSPs were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FTIR), zeta potential system, thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM). The average diameter of the MSPs was 220 nm, dispersed with well-proportioned size and magnetic resonance, the saturation magnetization was 3.64 A.mR/kg. MSP was coated with poly-L-lysine (PLL), and then the surface of PLL-MSP was combined with fluorescein isothiocynate (FITC). Results show that fluorescent/magnetic starch particles (FMSPs) are of stable photo-bleaching capability compared with free FITC, with low bio-toxicity and certain function of magnetic separation. It is expected that FMSPs are bifimctional nano-materials including fluorescence labelling and magnetic separation.
文摘A new combined desulfurization/denitration (DeSOx/DeNOx,) process was tested in this study. The process uses the so-called powder-particle fluidized bed (PPFB) as the major reactor in which a coarse DeNOx catalyst, several hundred micrometers in size, is fluidized by flue gas as the fluidization medium particles, while a continuously supplied fine DeSOx sorbent, several to tens of micrometers in diameter, is entrained with the flue gas. Ammonia for NOx reduction is fed to the bottom of the bed, thus, SOX and NOX are simultaneously removed in the single reactor. By adopting a model gas, SO2-NO-H2O-N2-air, to simulate actual flue gas in a laboratory-scale PPFB, simultaneous SO2 and NO removals were explored with respect to various gas components of flue gas. It was found that the variations of SO2 removal with concentrations (fractions) of oxygen, water vapor, SO2 and NO in flue gas are little affected by the simultaneous NOx reduction. However, the dependencies of NO removal upon such gas components are closely related to the inter-actions between DeSOx sorbent and DeNOx catalyst.
基金Projects(51772081,51837009,51971091)supported by the National Natural Science Foundation of ChinaProject(HFZL2018CXY003-4)supported by the Industry-University-Research Cooperation of AECC,ChinaProject(kq1902046)supported by the Major Science and Technology Projects of Changsha City,China。
文摘Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.
文摘Raw corn starch granules were hydrolysized by glucoamylase in a chemostat. The hydro- lysis of three different-sized granules shows that smaller granules undergo more hydrolyzation than larger ones. After 78 h, 9700 of the granules was hydrolysized with diameter between 0.15 mm and 0.3 mm at 50 ℃. When corn starch concentration increased from 100 g/L to 250 g/L, the amount of reducing sugar produced was proportional to the initial substrate concentration and no substrate inhibition phenomenon appeared. In order to study the product inhibition exactly, the product from hydrolysis reaction itself was added into the hydrolysis system at the beginning of starch hydrolysis. Product inhibition with different quantities of product added were studied in the initial several hours, during which period enzyme inactivation could be neglected and product inhibition could be studied separately. The experiments indicate that product inhibition happens when the additional quantity exceeds 9.56 g/L.
基金Project(2011GH561685)supported by the China Torch Program
文摘Pelletization is one of useful processes for the agglomeration of iron ore or concentrates. However, manganese ore fines are mainly agglomerated by sintering due to its high combined water which adversely affects the roasting performance of pellets. In this work, high pressure roll grinding(HPRG) process and optimization of temperature elevation system were investigated to improve the strength of fired manganese ore pellets. It is shown that the manganese ore possesses good ballability after being pretreated by HPRG twice, and good green balls were produced under the conditions of blending 2.0% bentonite in the feed, balling for 7 min at 16.00% moisture. High quality roasted pellets with the compressive strength of 2711 N per pellet were manufactured through preheating at 1050 °C for 10 min and firing at 1335 °C for 15 min by controlling the cracks formation. The fired manganese pellets keep the strength by the solid interconnection of recrystallized pyrolusite grains and the binding of manganite liquid phase which filled the pores and clearance among minerals. The product pellets contain high Mn grade and low impurities, and can be used to smelt ferromanganese, which provides a possible way to use imported manganese ore fines containing high combined water to produce high value ferromanganese.
基金financial supports from the Scientific and Technological Research Council of Turkey(No.215M895)。
文摘This study was carried out to investigate the possibility of titanium alloy metal powder production using low-power plasma torches.An argon DC non-transferred arc plasma torch was designed,and numerical analysis was conducted to determine the plasma jet properties and wire temperature.The highest velocities inside the nozzle attachment were between 838 and 1178 m/s.The velocities of the jets at the apex were between 494 and 645 m/s for different gas flow rates.The studied plasma gas flow rates had no significant effect on the effective plasma jet length.It was shown that the plasma jet length can be estimated by numerical analysis using the temperature and velocity changes of the plasma jet over distance.It was observed that the powders produced were spherical without any satellites.As a result of this study,a plasma torch was developed and powder production was performed successfully by using relatively low torch power.
文摘Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.
基金Supported by the Slovak Research and Development Agency under the contracts(APVV-0222-10)the Operational Program"Research and Development"financed through European Regional Development Fund(ITMS 26220220105)the Scientific Grant Agency of the Ministry of Education of Slovak Republic and the Slovak Academy of Sciences,projects(VEGA 1/0861/12,VEGA 1/0862/12,VEGA VEGA 2/0155/12)
文摘Soft magnetic composites (SMCs) were prepared from three different ferromagnetic powder particles: iron powder ASC 100.29, spherical FeSi particles and vitroperm (Fe73CulNb3Si16B7) flakes. Two types of hybrid organic-inorganic phenolic resins modified with either silica nanoparticles or boron were used to design a thin insulating layer perfect- ly covering the ferromagnetic particles. Fourier transform infrared (FTIR) spectrometry confirmed an incorporation of silica or boron into the polymer matrix, which manifested itself through an improved thermal stability of the hybrid resins verified by thermogravimetric-differential scanning calorimetry (TG-DSC) analysis. The core-shell particles prepared from the ferromagnetic powder particles and the modified hybrid resins were further compacted to the cylindrical and toroidal shapes for the mechanical, electrical and magnetic testing. A uniform distribution of the resin between the ferromagnetic particles was evidenced by scanning electron microscope (SEM) analysis, which was also reflected in a rather high value of the electrical resistivity. A low porosity and extraordinary high values of mechanical hardness and flexural strength were found in SMC consisting of the iron powder and phenolic resin modified with boron. The coercive fields of the prepared samples were comparable with the commercial SMCs.
文摘This paper discussed impact of temperature on the size distribution in preparing ultrafine silica from rice husk.The samples prepared were analyzed with infrared spectrum,and the relation between the particle size and intensity of characteristic absorption peak of IR at center around 1 100 cm-1 was disscussed with the baseline method.Results show that when the temperature is 650 ℃ and roasting time is 11 h,at optimal reaction conditions,the size distribution of the ultrafine silica powder prepared is relatively concentrated,and the average particle size is 199.5 nm.Moreover,the characteristic absorption band of IR is broadening gradually along with particle size decreasing.
基金supported by the National Natural Science Foundation of China (Grant No.50808045)Natural Science Foundation of Beijing(Grant No.2112024)Fok Ying Tung Education Foundation (GrantNo.132016)
文摘The effect of ground granulated blast-furnace slag(GGBFS) and silica fume(SF) on the chloride migration through concrete subjected to repeated loading was examined.Portland cement was replaced by 20%,30%,40% GGBFS and 5%,10% SF,respectively.Five times repeated loadings were applied to specimens,the maximum loadings were 40% and 80% of the axial cylinder compressive strength(f′c),respectively.Chloride migration through concretes was evaluated using the rapid chloride migration test and the chloride concentration in the anode chamber was measured.The results indicate that the transport number of chloride through concrete containing 20% and 30% GGBFS replacements and 5% and 10% SF replacements is lower than that of the control concrete,but 40% GGBFS replacement increases the transport number of chloride.Five loadings at 40% f′cor 80% f′c increase the transport number of chloride for all mixes investigated in this study.5% SF replacement has a very close effect on the chloride permeability of concrete with 20% GGBFS when concrete is subjected to 40% f′cor 80% f′c.
基金supported by the National Natural Science Foundation of China (21601159, 61604132, 61505033, 11374296, 61404039)the National Science Fund for Distinguished Young Scholars (61425021)
文摘Nanocarbon as an eco-friendly and abundant material has strong multi-color fluorescence, which makes it a promising candidate for healthy lighting and display. However, the low fluorescence efficiency and poor stability of multi-color carbon nanoparticle(CNP) phosphors are main hurdles that hinder their applications. This work demonstrated efficient and stable multi-color CNP phosphors through synergy between inner polar groups and outer silica matrix. The polar groups in polyethylene glycol(PEG) 6,000 are favor of high fluorescence of the CNP phosphors, and the low melting point(64℃) of PEG 6,000 helps to improve the thermal stability of the phosphors, while the silica matrix provides protection to the phosphors. Based on this design,blue, green, yellow and red CNP phosphors with photoluminescence quantum yield of 53.1%, 47.4%, 43.8% and 42.3% have been achieved, all of which are the best values in ever reported multi-color CNP phosphors. Furthermore, the fluorescence of the CNP phosphors keeps almost unchanged at 100℃ and degrades little in one month, indicating their good thermal tolerance and temporal stability. In addition, multicolor devices including white light-emitting devices(LEDs)have been realized by coating the CNP phosphors onto UV chips. The luminous efficiency, correlated color temperature,Commission Internationale de L'Eclairage and color rendering index of the white LED can reach 12 lm W^-1, 6,107 K,(0.32, 0.33) and 89, respectively, indicating the potential applications of the CNP phosphors in lighting and display.
基金the National Natural Science Foundation of China (21161016)the Natural Science Foundation of Jiangxi Province (20142BAB216013)+1 种基金Jiangxi Education Department Fund (KJLD14087, GJJ14714)Jiangxi Environmental Protection Department Fund ([2013]370)
文摘Low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O nanopowders(NPs)would determine their practical application in purifying wastewater.In this contribution,ZnO NPs were scalably synthesized via the simple reaction of Zn powder with H_2O vapor in autoclave.The structural,morphological and optical properties of the samples were systematically characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectra,transmission electron microscopy,Micro-Raman,photoluminescence,and ultraviolet-visible spectroscopy.The as-prepared Zn O NPs are composed of nanoparticles with 100–150 nm in diameter,and have a small Brunauer-Emmett-Teller surface area of 6.85 m^2/g.The formation of Zn O nanoparticles is relative to the peeling of H_2 release.Furthermore,the product has big strain-stress leading to the red-shift in the band gap of product,and shows a strong green emission centered at 515 nm revealing enough atomic defects in Zn O NPs.As a comparison with P25,the obtained dust gray Zn O NPs have a strong absorbance in the region of 200–700 nm,suggesting the wide wave-band utilization in sunlight.Based on the traits above,the Zn O NPs show excellent photocatalytic activity on the degradation of rhodamine B(Rh-B)under solar light irradiation,close to that under UV irradiation.Importantly,the Zn O NPs could be well recycled in water due to the quick sedimentation in themselves in solution.The low-cost and scalable preparation,high photocatalytic activity,and convenient recycle of Zn O NPs endow themselves with promising application in purifying wastewater.