In the article titled“Neuroprotection mediated by the Wnt/Frizzled signaling pathway in early brain injury induced by subarachnoid hemorrhage,”published on pages 1013-1024,Issue 6,Volume 14 of Neural Regeneration Re...In the article titled“Neuroprotection mediated by the Wnt/Frizzled signaling pathway in early brain injury induced by subarachnoid hemorrhage,”published on pages 1013-1024,Issue 6,Volume 14 of Neural Regeneration Research(Wang et al.,2019),there are some errors in selecting the appropriate images in Figures 4A,4B,and 5A by authors during assembling the images.展开更多
Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For inst...Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For instance,Al-O reaction is the most common pathway to release limited energy while Al-F reaction has received much attentions to enhance Al combustion efficiency.However,microscopic understanding of the Al-O/Al-F reaction dynamics remains unsolved,which is fundamentally necessary to further improve Al combustion efficiency.In this work,for the first time,Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles(n-Al)in oxygen/fluorine containing environments have been revealed via reactive molecular dynamics(RMD)simulations meshing together combustion experiments.Three RMD simulation systems of Al core/O_(2)/HF,n-Al/O_(2)/HF,and n-Al/O_(2)/CF4 with oxygen percentage ranging from 0%to 100%have been performed.The n-Al combustion in mixed O_(2)/CF_4 environments have been conducted by constant volume combustion experiments.RMD results show that Al-O reaction exhibits kinetic benefits while Al-F reaction owns thermodynamic benefits for n-Al combustion.In n-Al/O_(2)/HF,Al-O reaction gives faster energy release rate than Al-F reaction(1.1 times).The optimal energy release efficiency can be achieved with suitable oxygen percentage of 10%and 50%for n-Al/O_(2)/HF and n-Al/O_(2)/CF_4,respectively.In combustion experiments,90%of oxygen percentage can optimally enhance the peak pressure,pressurization rate and combustion heat.Importantly,Al-O reaction prefers to occur on the surface regions while Al-F reaction prefers to proceed in the interior regions of n-Al,confirming the kinetic/thermodynamic benefits of Al-O/Al-F reactions.The synergistic effect of Al-O/Al-F reaction for greatly enhancing n-Al combustion efficiency is demonstrated at atomicscale,which is beneficial for optimizing the combustion performance of metallic fuel.展开更多
Al80Ni6 Y8 Co4 Cu2 amorphous ribbons were isothermally annealed and a mixed structure consisting of α-Al particle with a size of less than 15nm and Al3Ni compound with a size of about 30nm was obtained. The crystall...Al80Ni6 Y8 Co4 Cu2 amorphous ribbons were isothermally annealed and a mixed structure consisting of α-Al particle with a size of less than 15nm and Al3Ni compound with a size of about 30nm was obtained. The crystallization kinetics of Al80Ni6 Y8 Co4 Cu2 amorphous alloy shows that the precipitation of α-Al particles is the growth process controlled by diffusion of the solute elements rejected from the growing crystals. By quenching at different cooling rates, a mixed structure consisting of nanoscale α-Al particles and the remaining glass matrix or structure consisting of nanoscale particle (Al phase or Al3Ni compound) with a size of about 100nm was formed. The addition of Co elements and Cu elements to Al-Ni-Y alloy systems increases the glass formation ability of the alloy and the thermal stability of the supercooled liquid region against crystallization, which results from significant difference of atomic size, strong bonding nature among constituent elements and the low diffisivity of the solute elements due to the concentration gradient in the growing front of crystals.展开更多
The influence of annealing cycles up to 650 °C on the specific conductivity and hardness(HV) of hot-rolled sheets of Al alloys containing up to 0.5% Zr(mass fraction) was studied.Using analytical calculations...The influence of annealing cycles up to 650 °C on the specific conductivity and hardness(HV) of hot-rolled sheets of Al alloys containing up to 0.5% Zr(mass fraction) was studied.Using analytical calculations of phase composition and experimental methods(scanning electron microscopy,transmission electron microscopy,electron microprobe analysis,etc),it is demonstrated that the conductivity depends on the content of Zr in the Al solid solution which is the minimum after holding at 450 °C for 3 h.On the other hand,the hardness of the alloy is mainly caused by the amount of nanoparticles of the L12(Al3Zr) phase that defines the retention of strain hardening.It is shown that the best combination of electrical conductivity and hardness values can be reached within an acceptable holding time at the temperature about 450 °C.展开更多
Cold-rolled Ti/Al laminated composites were annealed at 525−625℃for 0−128 h,and the interfacial microstructure evolution was investigated.The results indicate that only the TiAl_(3) phase was formed at the Ti/Al inte...Cold-rolled Ti/Al laminated composites were annealed at 525−625℃for 0−128 h,and the interfacial microstructure evolution was investigated.The results indicate that only the TiAl_(3) phase was formed at the Ti/Al interface;most of TiAl_(3) grains were fine equiaxed with average sizes ranging from hundreds of nanometers to several microns and the TiAl_(3) grain size increased with increasing annealing time and/or temperature,but the effect of annealing temperature on the TiAl_(3) grain size was far greater than that of annealing time.The growth of the TiAl_(3) phase consisted of two stages.The initial stage was governed by chemical reaction with a reaction activation energy of 195.75 kJ/mol,and the reaction rate constant of the TiAl_(3) phase was larger as the Ti/Al interface was bonded with fresh surfaces.At the second stage,the growth was governed by diffusion,the diffusion activation energy was 33.69 kJ/mol,and the diffusion growth rate constant of the TiAl_(3) phase was mainly determined by the grain boundary diffusion owing to the smaller TiAl_(3) grain size.展开更多
Developing multi phase alloy is an effective approach for the strengthening and toughening of the L1 2 Al 3Ti alloy. A Nb modified Al 3Ti base alloy which has a L1 2 matrix and the precipitated second phase has been d...Developing multi phase alloy is an effective approach for the strengthening and toughening of the L1 2 Al 3Ti alloy. A Nb modified Al 3Ti base alloy which has a L1 2 matrix and the precipitated second phase has been developed. Since the effect of second phase is strongly influenced by its size and distribution, high energy ball milling was employed to fabricate the alloy in comparison with the conventional casting process. It was found that structure evolution during mechanical milling is different for DO 22 , L1 2 and L1 2+DO 22 two phase alloys. The DO 22 Al 3Ti transformed only to a FCC structure even after long time milling. The ordering of L1 2 Al 67 Ti 25 Mn 8 decreased quickly and changed into a FCC structure after short time milling, subsequent milling led to the amorphous transition. The DO 22 phase in Al 3Ti Mn Nb alloys dissolved into the L1 2 matrix quickly in the early stage of milling and the matrix changed into a FCC supersaturated solid solution after 10 h milling, further milling led to the amorphous transition. Reordering of the metastable structures occurred during the annealing process. The consolidated materials consisting of fine equiaxed grains with dispersed particles exhibited remarkable improvement of strength and promising ductility.展开更多
Bulk metallic glass Zr_52.5Ni_14.6Al_10Cu_17.9Ti_5 was prepared by melt injection casting method. Its glass transition and crystallization temperatures were determined by differential scanning calorimetry (DSC) to be ...Bulk metallic glass Zr_52.5Ni_14.6Al_10Cu_17.9Ti_5 was prepared by melt injection casting method. Its glass transition and crystallization temperatures were determined by differential scanning calorimetry (DSC) to be 631 K and 710 K respectively. By analysis of X-ray diffractometry (XRD) and transmission electron microscopy (TEM ), the predominant crystallized phase of Zr_2Ni0.67O0.33 distributed on glass state matrix was detected after annealing at 673 K for 600 s. The transformation to Zr_2Ni_0.67O_0.33 and a small amount of ZrAl and Zr_2Cu took place after annealing for 600 s at temperature from 703 K to 723 K. With increasing annealing temperature from 753 K to 823 K, the amounts of ZrAl and Zr_2Cu increased, but the size of the crystals did not significantly change. The transformation to Zr_2Ni_0.67O_0.33 is interface-controlled, but is diffusion-controlled to Zr_2Cu and ZrAl. With increasing annealing temperature up to 200 K above T_x, the nanometer grains became very fine because of the increase of nucleation rate for Zr_2Cu and ZrAl.展开更多
A new method for corrosion protection of Al-based metal matrix composites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance...A new method for corrosion protection of Al-based metal matrix composites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves. The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for Al6061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.展开更多
Chemical and field-effect passivation of atomic layer deposition (ALD) Al2O3 films are investigated, mainly by corona charging measurement. The interface structure and material properties are characterized by transm...Chemical and field-effect passivation of atomic layer deposition (ALD) Al2O3 films are investigated, mainly by corona charging measurement. The interface structure and material properties are characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. Passivation performance is improved remarkably by annealing at temperatures of 450 ℃ and 500 ℃, while the improvement is quite weak at 600 ℃, which can be attributed to the poor quality of chemical passivation. An increase of fixed negative charge density in the films during annealing can be explained by the Al2O3/Si interface structural change. The Al–OH groups play an important role in chemical passivation, and the Al–OH concentration in an as-deposited film subsequently determines the passivation quality of that film when it is annealed, to a certain degree.展开更多
High-performance thin-film transistors (TFTs) with a low thermal budget are highly desired for flexible electronic applications. In this work, the TFTs with atomic layer deposited ZnO-channel/Al2O3-dielectric are fa...High-performance thin-film transistors (TFTs) with a low thermal budget are highly desired for flexible electronic applications. In this work, the TFTs with atomic layer deposited ZnO-channel/Al2O3-dielectric are fabricated under the maximum process temperature of 200℃. First, we investigate the effect of post-annealing environment such as N2, H2-N2 (4%) and O2 on the device performance, revealing that o2 annealing can greatly enhance the device performance. Further, we compare the influences of annealing temperature and time on the device performance. It is found that long anneMing at 200℃is equivalent to and even outperforms short annealing at 300℃. Excellent electrical characteristics of the TFTs are demonstrated after 02 anneMing at 200℃ for 35 rain, including a low off-current of 2.3 × 10-13 A, a small sub-threshold swing of 245 m V/dec, a large on/off current ratio of 7.6×10s, and a high electron effective mobility of 22.1cm2/V.s. Under negative gate bias stress at -10 V, the above devices show better electrical stabilities than those post-annealed at 300℃. Thus the fabricated high-performance ZnO TFT with a low thermal budget is very promising for flexible electronic applications.展开更多
Effect of annealing temperature and time on the microstructure and photoluminescence(PL)properties of Al doped ZnO thin films deposited on Si(100)substrates by sol-gel method was investigated.An X-ray diffraction(XRD)...Effect of annealing temperature and time on the microstructure and photoluminescence(PL)properties of Al doped ZnO thin films deposited on Si(100)substrates by sol-gel method was investigated.An X-ray diffraction(XRD)was used to analyze the structural properties of the thin films.All the thin films have a preferential c-axis orientation,which are enhances in the annealing process.It is found from the PL measurement that near band edge(NBE)emission and deep-level(DL)emissions are observed in as-grown ZnO∶Al thin films.However,the intensity of DLE is much smaller than that of NBE.Enhancement of NBE is clearly observed after thermal annealing in air and the intensity of NBE increases with annealing temperature.Results also show that the PL spectrum is dependent not only on the processing temperature but also on the processing time.The DLE related defects can not be removed by annealing,and on the contrary,the annealing conditions actually favor their formation.展开更多
High-temperature annealing of the atomic layer deposition (ALD) of Al2O3 films on 4H-SiC in O 2 atmosphere is studied with temperature ranging from 800℃ to 1000℃. It is observed that the surface morphology of Al2O...High-temperature annealing of the atomic layer deposition (ALD) of Al2O3 films on 4H-SiC in O 2 atmosphere is studied with temperature ranging from 800℃ to 1000℃. It is observed that the surface morphology of Al2O3 films annealed at 800℃ and 900℃ is pretty good, while the surface of the sample annealed at 1000℃ becomes bumpy. Grazing incidence X-ray diffraction (GIXRD) measurements demonstrate that the as-grown films are amorphous and begin to crystallize at 900℃. Furthermore, C–V measurements exhibit improved interface characterization after annealing, especially for samples annealed at 900℃ and 1000℃. It is indicated that high-temperature annealing in O2 atmosphere can improve the interface of Al2O3 /SiC and annealing at 900℃ would be an optimum condition for surface morphology, dielectric quality, and interface states.展开更多
The tri-metal Ti-Al-Nb composites were processed through three procedures:hot pressing,rolling,and hot pressing,followed by subsequent rolling.The fabricated composites were then subjected to annealing at 600,625,and ...The tri-metal Ti-Al-Nb composites were processed through three procedures:hot pressing,rolling,and hot pressing,followed by subsequent rolling.The fabricated composites were then subjected to annealing at 600,625,and 650℃ temperatures at different times.Microstructure observation at the interfaces reveals that the increase in plastic deformation strain significantly affects TiAl_(3) intermetallic layers’evolution and accelerates the layers’growth.On the contrary,the amount of applied strain does not significantly affect the evolution of the NbAl_(3) intermetallic layer thickness.It was also found that Al and Ti atoms’diffusion has occurred throughout the TiAl_(3) layer,but only Al atoms diffuse through the NbAl_(3) layer.The slow growth rate of the NbAl_(3) intermetallic layer is due to the lack of diffusion of Nb atoms and the high activation energy of Al atoms’reaction with Nb atoms.展开更多
In this paper, the effect of alumina thickness on Al2O3/InP interface with post deposition annealing (PDA) in the oxygen ambient is studied. Atomic layer deposited (ALD) Al2O3 films with four different thickness v...In this paper, the effect of alumina thickness on Al2O3/InP interface with post deposition annealing (PDA) in the oxygen ambient is studied. Atomic layer deposited (ALD) Al2O3 films with four different thickness values (5 nm, 7 nm, 9 nm, 11 rim) are deposited on InP substrates. The capacitance-voltage (C-V) measurement shows a negative correlation between the alumina thickness and the frequency dispersion. The X-ray photoelectronspectroscopy (XPS) data present significant growth of indium-phosphorus oxide near the Al2O3/InP interface, which indicates serious oxidation of InP during the oxygen annealing. The hysteresis curve shows an optimum thickness of 7 nm after PDA in an oxygen ambient at 500 ℃ for 10 min. It is demonstrated that both sides of the interface are impacted by oxygen during post deposition annealing. It is suggested that the final state of the interface is of reduced positively charged defects on Al2O3 side and oxidized InP, which degrades the interface.展开更多
Lu3Al5O12 single crystals grown in pure N2 atmosphere by Czochralski method were annealed in oxidizing atmosphere (air)and reducing atmosphere (H2 + N2), respectively. Effects of annealing treatments on luminesce...Lu3Al5O12 single crystals grown in pure N2 atmosphere by Czochralski method were annealed in oxidizing atmosphere (air)and reducing atmosphere (H2 + N2), respectively. Effects of annealing treatments on luminescence and scintillation properties of the crystals were investigated. The crystal annealed in air showed the highest luminescence intensity under blue light or vacuum ultraviolet excitation in comparison with that annealed in reducing flux or the as-grown crystal. Under X-ray excitation, crystal annealed in reducing atmosphere had the lowest light yield, and crystal annealed in air had the fastest decay time under ^137Cs 662 keV γ-ray excitation. Different annealing treatments resulted in different luminescence and scintillation properties, which might related with oxygen vacancies or defect existing in the crystals.展开更多
The effects of Fe content on the microstructure,phase constituents and microhardness of the as-cast,800℃or 1000℃-annealed Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=13−66)alloys were investigated.Not all these alloys are compos...The effects of Fe content on the microstructure,phase constituents and microhardness of the as-cast,800℃or 1000℃-annealed Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=13−66)alloys were investigated.Not all these alloys are composed of the single FCC phase.The BCC and B2 phases are found.It is confirmed that the BCC phase in the Al7Cr20Fe66Ni7 alloy is transformed from the FCC phase at about 900℃ during cooling.While in the 800℃-annealed Al7Cr20Fe60Ni13 alloy,the FCC phase is stable and the hardness decreases.After annealing at 1000℃,for the precipitation of the B2 particles,the Al content in the FCC phase decreases,which results in decreasing of the alloy hardness.Moreover,after annealing at 800℃,a small amount of Al-rich B2 particles precipitate at the phase boundary and some nanocrystal BCC phase precipitates in the FCC matrix,which increases the hardness of the Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=41−49)alloys.These results will help to the composition design and processing design of the Al−Cr−Fe−Ni based high-entropy alloys.展开更多
The article by Lan et al.[1],published on 30 October 2021 in Hepatology,showed the relationship between the natural flavonoid compound breviscapine and nonalcoholic steatohepatitis(NASH).The researchers demonstrated t...The article by Lan et al.[1],published on 30 October 2021 in Hepatology,showed the relationship between the natural flavonoid compound breviscapine and nonalcoholic steatohepatitis(NASH).The researchers demonstrated that breviscapine might be a novel therapeutic candidate for the treatment of NASH.It can be proven that breviscapine prevents metabolic stress-induced NASH progression through direct inhibition of the TGF-β-activated Kinase 1(TAK1)signaling pathway.展开更多
Familial dysautonomia(FD,OMIM 223900;also known as HSAN III or Riley-Day syndrome) is the most prevalent form of hereditary sensory and autonomic neuropathy(HSAN;Axelrod et al., 1974). Patients suffering from autonomi...Familial dysautonomia(FD,OMIM 223900;also known as HSAN III or Riley-Day syndrome) is the most prevalent form of hereditary sensory and autonomic neuropathy(HSAN;Axelrod et al., 1974). Patients suffering from autonomic and sensory nervous system impairment have no available effective treatment and the average age of death is approximately 24 years.展开更多
Amyotrophic lateral sclerosis is a fatal neurodegenerative disorder characterized by upper and lower motor neuron degeneration, which leads to progressive paralysis of skeletal muscles and, ultimately, respiratory fai...Amyotrophic lateral sclerosis is a fatal neurodegenerative disorder characterized by upper and lower motor neuron degeneration, which leads to progressive paralysis of skeletal muscles and, ultimately, respiratory failure between 2–5 years after symptom onset. Unfortunately, currently accepted treatments for amyotrophic lateral sclerosis are extremely scarce and only provide modest benefit. As a consequence, a great effort is being done by the scientific community in order to achieve a better understanding of the different molecular and cellular processes that influence the progression and/or outcome of this neuropathological condition and, therefore, unravel new potential targets for therapeutic intervention. Interestingly, a growing number of experimental evidences have recently shown that, besides its well-known physiological roles in the developing and adult central nervous system, the Wnt family of proteins is involved in different neuropathologica conditions, including amyotrophic lateral sclerosis. These proteins are able to modulate, at least, three different signaling pathways, usually known as canonical(β-catenin dependent) and non-canonical(β-catenin independent) signaling pathways. In the present review, we aim to provide a general overview of the current knowledge that supports the relationship between the Wnt family of proteins and its associated signaling pathways and amyotrophic lateral sclerosis pathology, as well as their possible mechanisms of action. Altogether, the currently available knowledge suggests that Wnt signaling modulation might be a promising therapeutic approach to ameliorate the histopathological and functional deficits associated to amyotrophic lateral sclerosis, and thus improve the progression and outcome of this neuropathology.展开更多
Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in...Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in Al 1100 alloy has been studied in detail.Before subjecting to 50%cryorolling,samples were pre-annealed at 250℃ for 2 h and pre-solution treated at 540℃ for 1 h.X-ray diffraction and HRTEM techniques were used to understand the crystallite size,lattice strain and dislocation configuration in the processed alloy.The results indicate that the pre-annealed sample has the highest grain aspect ratio(4.43),the smallest crystallite size(37.53 nm),the highest lattice strain(9.12×10^(−3))and the highest dislocation density(45.16×10^(13) m^(−2))among the tested sample.The pre-annealed sample shows a significant improvement of 43.44%,24.64%and 20.33%in hardness,ultimate tensile strength and yield strength.Both pre-annealed and pre-solution treated samples show improved corrosion resistance when compared to cryorolled samples without any pre-treatment,with the pre-annealed sample showing the best corrosion resistance.展开更多
文摘In the article titled“Neuroprotection mediated by the Wnt/Frizzled signaling pathway in early brain injury induced by subarachnoid hemorrhage,”published on pages 1013-1024,Issue 6,Volume 14 of Neural Regeneration Research(Wang et al.,2019),there are some errors in selecting the appropriate images in Figures 4A,4B,and 5A by authors during assembling the images.
基金support by the National Natural Science Foundation of China(NSFC,Grant Nos.12002324,12372341,12172342)。
文摘Improving the energy conversion efficiency in metallic fuel(e.g.,Al)combustion is always desirable but challenging,which often involves redox reactions of aluminum(Al)with various mixed oxidizing environments.For instance,Al-O reaction is the most common pathway to release limited energy while Al-F reaction has received much attentions to enhance Al combustion efficiency.However,microscopic understanding of the Al-O/Al-F reaction dynamics remains unsolved,which is fundamentally necessary to further improve Al combustion efficiency.In this work,for the first time,Al-O/Al-F reaction dynamic effects on the combustion of aluminum nanoparticles(n-Al)in oxygen/fluorine containing environments have been revealed via reactive molecular dynamics(RMD)simulations meshing together combustion experiments.Three RMD simulation systems of Al core/O_(2)/HF,n-Al/O_(2)/HF,and n-Al/O_(2)/CF4 with oxygen percentage ranging from 0%to 100%have been performed.The n-Al combustion in mixed O_(2)/CF_4 environments have been conducted by constant volume combustion experiments.RMD results show that Al-O reaction exhibits kinetic benefits while Al-F reaction owns thermodynamic benefits for n-Al combustion.In n-Al/O_(2)/HF,Al-O reaction gives faster energy release rate than Al-F reaction(1.1 times).The optimal energy release efficiency can be achieved with suitable oxygen percentage of 10%and 50%for n-Al/O_(2)/HF and n-Al/O_(2)/CF_4,respectively.In combustion experiments,90%of oxygen percentage can optimally enhance the peak pressure,pressurization rate and combustion heat.Importantly,Al-O reaction prefers to occur on the surface regions while Al-F reaction prefers to proceed in the interior regions of n-Al,confirming the kinetic/thermodynamic benefits of Al-O/Al-F reactions.The synergistic effect of Al-O/Al-F reaction for greatly enhancing n-Al combustion efficiency is demonstrated at atomicscale,which is beneficial for optimizing the combustion performance of metallic fuel.
文摘Al80Ni6 Y8 Co4 Cu2 amorphous ribbons were isothermally annealed and a mixed structure consisting of α-Al particle with a size of less than 15nm and Al3Ni compound with a size of about 30nm was obtained. The crystallization kinetics of Al80Ni6 Y8 Co4 Cu2 amorphous alloy shows that the precipitation of α-Al particles is the growth process controlled by diffusion of the solute elements rejected from the growing crystals. By quenching at different cooling rates, a mixed structure consisting of nanoscale α-Al particles and the remaining glass matrix or structure consisting of nanoscale particle (Al phase or Al3Ni compound) with a size of about 100nm was formed. The addition of Co elements and Cu elements to Al-Ni-Y alloy systems increases the glass formation ability of the alloy and the thermal stability of the supercooled liquid region against crystallization, which results from significant difference of atomic size, strong bonding nature among constituent elements and the low diffisivity of the solute elements due to the concentration gradient in the growing front of crystals.
基金Project(RMEF157814X0004)supported by the Ministry of Education and Science of the Russian Federation
文摘The influence of annealing cycles up to 650 °C on the specific conductivity and hardness(HV) of hot-rolled sheets of Al alloys containing up to 0.5% Zr(mass fraction) was studied.Using analytical calculations of phase composition and experimental methods(scanning electron microscopy,transmission electron microscopy,electron microprobe analysis,etc),it is demonstrated that the conductivity depends on the content of Zr in the Al solid solution which is the minimum after holding at 450 °C for 3 h.On the other hand,the hardness of the alloy is mainly caused by the amount of nanoparticles of the L12(Al3Zr) phase that defines the retention of strain hardening.It is shown that the best combination of electrical conductivity and hardness values can be reached within an acceptable holding time at the temperature about 450 °C.
基金the financial supports from the S&T Program of Hebei Province,China(No.20373901D)the National Natural Science Foundation of China(Nos.51807047,51804095)+2 种基金the National Science Foundation of Hebei Province,China(No.E2019402433)the Youth Top Talents Science and Technology Research Project of Hebei Province University,China(No.BJ2019003)the Research and Development Project of Science and Technology of Handan City,China(No.19422111008-19).
文摘Cold-rolled Ti/Al laminated composites were annealed at 525−625℃for 0−128 h,and the interfacial microstructure evolution was investigated.The results indicate that only the TiAl_(3) phase was formed at the Ti/Al interface;most of TiAl_(3) grains were fine equiaxed with average sizes ranging from hundreds of nanometers to several microns and the TiAl_(3) grain size increased with increasing annealing time and/or temperature,but the effect of annealing temperature on the TiAl_(3) grain size was far greater than that of annealing time.The growth of the TiAl_(3) phase consisted of two stages.The initial stage was governed by chemical reaction with a reaction activation energy of 195.75 kJ/mol,and the reaction rate constant of the TiAl_(3) phase was larger as the Ti/Al interface was bonded with fresh surfaces.At the second stage,the growth was governed by diffusion,the diffusion activation energy was 33.69 kJ/mol,and the diffusion growth rate constant of the TiAl_(3) phase was mainly determined by the grain boundary diffusion owing to the smaller TiAl_(3) grain size.
文摘Developing multi phase alloy is an effective approach for the strengthening and toughening of the L1 2 Al 3Ti alloy. A Nb modified Al 3Ti base alloy which has a L1 2 matrix and the precipitated second phase has been developed. Since the effect of second phase is strongly influenced by its size and distribution, high energy ball milling was employed to fabricate the alloy in comparison with the conventional casting process. It was found that structure evolution during mechanical milling is different for DO 22 , L1 2 and L1 2+DO 22 two phase alloys. The DO 22 Al 3Ti transformed only to a FCC structure even after long time milling. The ordering of L1 2 Al 67 Ti 25 Mn 8 decreased quickly and changed into a FCC structure after short time milling, subsequent milling led to the amorphous transition. The DO 22 phase in Al 3Ti Mn Nb alloys dissolved into the L1 2 matrix quickly in the early stage of milling and the matrix changed into a FCC supersaturated solid solution after 10 h milling, further milling led to the amorphous transition. Reordering of the metastable structures occurred during the annealing process. The consolidated materials consisting of fine equiaxed grains with dispersed particles exhibited remarkable improvement of strength and promising ductility.
文摘Bulk metallic glass Zr_52.5Ni_14.6Al_10Cu_17.9Ti_5 was prepared by melt injection casting method. Its glass transition and crystallization temperatures were determined by differential scanning calorimetry (DSC) to be 631 K and 710 K respectively. By analysis of X-ray diffractometry (XRD) and transmission electron microscopy (TEM ), the predominant crystallized phase of Zr_2Ni0.67O0.33 distributed on glass state matrix was detected after annealing at 673 K for 600 s. The transformation to Zr_2Ni_0.67O_0.33 and a small amount of ZrAl and Zr_2Cu took place after annealing for 600 s at temperature from 703 K to 723 K. With increasing annealing temperature from 753 K to 823 K, the amounts of ZrAl and Zr_2Cu increased, but the size of the crystals did not significantly change. The transformation to Zr_2Ni_0.67O_0.33 is interface-controlled, but is diffusion-controlled to Zr_2Cu and ZrAl. With increasing annealing temperature up to 200 K above T_x, the nanometer grains became very fine because of the increase of nucleation rate for Zr_2Cu and ZrAl.
文摘A new method for corrosion protection of Al-based metal matrix composites (MMC) was developed using two-step process, which involves anodizing in H2SO4 solution and sealing in rare earth solution. Corrosion resistance of the treated surface was evaluated with polarization curves. The results showed that the effect of the protection using rare earth sealing is equivalent to that using chromate sealing for Al6061/SiCp. The rare earth metal salt can be an alternative to the toxic chromate for sealing anodized Al MMC.
基金Project supported by the National Natural Science Foundation of China(Grant No.61106060)the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.Y2YF028001)the National High Technology Research and Development Program of China(Grant No.2012AA052401)
文摘Chemical and field-effect passivation of atomic layer deposition (ALD) Al2O3 films are investigated, mainly by corona charging measurement. The interface structure and material properties are characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. Passivation performance is improved remarkably by annealing at temperatures of 450 ℃ and 500 ℃, while the improvement is quite weak at 600 ℃, which can be attributed to the poor quality of chemical passivation. An increase of fixed negative charge density in the films during annealing can be explained by the Al2O3/Si interface structural change. The Al–OH groups play an important role in chemical passivation, and the Al–OH concentration in an as-deposited film subsequently determines the passivation quality of that film when it is annealed, to a certain degree.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61474027 and 61376008
文摘High-performance thin-film transistors (TFTs) with a low thermal budget are highly desired for flexible electronic applications. In this work, the TFTs with atomic layer deposited ZnO-channel/Al2O3-dielectric are fabricated under the maximum process temperature of 200℃. First, we investigate the effect of post-annealing environment such as N2, H2-N2 (4%) and O2 on the device performance, revealing that o2 annealing can greatly enhance the device performance. Further, we compare the influences of annealing temperature and time on the device performance. It is found that long anneMing at 200℃is equivalent to and even outperforms short annealing at 300℃. Excellent electrical characteristics of the TFTs are demonstrated after 02 anneMing at 200℃ for 35 rain, including a low off-current of 2.3 × 10-13 A, a small sub-threshold swing of 245 m V/dec, a large on/off current ratio of 7.6×10s, and a high electron effective mobility of 22.1cm2/V.s. Under negative gate bias stress at -10 V, the above devices show better electrical stabilities than those post-annealed at 300℃. Thus the fabricated high-performance ZnO TFT with a low thermal budget is very promising for flexible electronic applications.
基金Project supported by the National Natural Science Foundation of China(60390073)
文摘Effect of annealing temperature and time on the microstructure and photoluminescence(PL)properties of Al doped ZnO thin films deposited on Si(100)substrates by sol-gel method was investigated.An X-ray diffraction(XRD)was used to analyze the structural properties of the thin films.All the thin films have a preferential c-axis orientation,which are enhances in the annealing process.It is found from the PL measurement that near band edge(NBE)emission and deep-level(DL)emissions are observed in as-grown ZnO∶Al thin films.However,the intensity of DLE is much smaller than that of NBE.Enhancement of NBE is clearly observed after thermal annealing in air and the intensity of NBE increases with annealing temperature.Results also show that the PL spectrum is dependent not only on the processing temperature but also on the processing time.The DLE related defects can not be removed by annealing,and on the contrary,the annealing conditions actually favor their formation.
基金the National Natural Science Foundation of China(Grant No.61106080)the Major Program of the National Natural Science Foundation of China(Grant No.2013ZX02305)
文摘High-temperature annealing of the atomic layer deposition (ALD) of Al2O3 films on 4H-SiC in O 2 atmosphere is studied with temperature ranging from 800℃ to 1000℃. It is observed that the surface morphology of Al2O3 films annealed at 800℃ and 900℃ is pretty good, while the surface of the sample annealed at 1000℃ becomes bumpy. Grazing incidence X-ray diffraction (GIXRD) measurements demonstrate that the as-grown films are amorphous and begin to crystallize at 900℃. Furthermore, C–V measurements exhibit improved interface characterization after annealing, especially for samples annealed at 900℃ and 1000℃. It is indicated that high-temperature annealing in O2 atmosphere can improve the interface of Al2O3 /SiC and annealing at 900℃ would be an optimum condition for surface morphology, dielectric quality, and interface states.
文摘The tri-metal Ti-Al-Nb composites were processed through three procedures:hot pressing,rolling,and hot pressing,followed by subsequent rolling.The fabricated composites were then subjected to annealing at 600,625,and 650℃ temperatures at different times.Microstructure observation at the interfaces reveals that the increase in plastic deformation strain significantly affects TiAl_(3) intermetallic layers’evolution and accelerates the layers’growth.On the contrary,the amount of applied strain does not significantly affect the evolution of the NbAl_(3) intermetallic layer thickness.It was also found that Al and Ti atoms’diffusion has occurred throughout the TiAl_(3) layer,but only Al atoms diffuse through the NbAl_(3) layer.The slow growth rate of the NbAl_(3) intermetallic layer is due to the lack of diffusion of Nb atoms and the high activation energy of Al atoms’reaction with Nb atoms.
基金supported by the National Natural Science Foundation of China(Grant No.61204006)the Fundamental Research Funds for the Central Universities,China(Grant No.K50511250002)the National Key Science and Technology Special Project,China(Grant No.2008ZX01002-002)
文摘In this paper, the effect of alumina thickness on Al2O3/InP interface with post deposition annealing (PDA) in the oxygen ambient is studied. Atomic layer deposited (ALD) Al2O3 films with four different thickness values (5 nm, 7 nm, 9 nm, 11 rim) are deposited on InP substrates. The capacitance-voltage (C-V) measurement shows a negative correlation between the alumina thickness and the frequency dispersion. The X-ray photoelectronspectroscopy (XPS) data present significant growth of indium-phosphorus oxide near the Al2O3/InP interface, which indicates serious oxidation of InP during the oxygen annealing. The hysteresis curve shows an optimum thickness of 7 nm after PDA in an oxygen ambient at 500 ℃ for 10 min. It is demonstrated that both sides of the interface are impacted by oxygen during post deposition annealing. It is suggested that the final state of the interface is of reduced positively charged defects on Al2O3 side and oxidized InP, which degrades the interface.
基金Project supported by the National Natural Science Foundation of China (20571088)the Science and Technology Project of Guangdong Province (2005B10301016, 2006B14801001)
文摘Lu3Al5O12 single crystals grown in pure N2 atmosphere by Czochralski method were annealed in oxidizing atmosphere (air)and reducing atmosphere (H2 + N2), respectively. Effects of annealing treatments on luminescence and scintillation properties of the crystals were investigated. The crystal annealed in air showed the highest luminescence intensity under blue light or vacuum ultraviolet excitation in comparison with that annealed in reducing flux or the as-grown crystal. Under X-ray excitation, crystal annealed in reducing atmosphere had the lowest light yield, and crystal annealed in air had the fastest decay time under ^137Cs 662 keV γ-ray excitation. Different annealing treatments resulted in different luminescence and scintillation properties, which might related with oxygen vacancies or defect existing in the crystals.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(51771035,51671037)Natural Science Foundation of Jiangsu Province,China(BK20161190)the Priority Academic Program of Jiangsu Higher Education Institutions,China.
文摘The effects of Fe content on the microstructure,phase constituents and microhardness of the as-cast,800℃or 1000℃-annealed Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=13−66)alloys were investigated.Not all these alloys are composed of the single FCC phase.The BCC and B2 phases are found.It is confirmed that the BCC phase in the Al7Cr20Fe66Ni7 alloy is transformed from the FCC phase at about 900℃ during cooling.While in the 800℃-annealed Al7Cr20Fe60Ni13 alloy,the FCC phase is stable and the hardness decreases.After annealing at 1000℃,for the precipitation of the B2 particles,the Al content in the FCC phase decreases,which results in decreasing of the alloy hardness.Moreover,after annealing at 800℃,a small amount of Al-rich B2 particles precipitate at the phase boundary and some nanocrystal BCC phase precipitates in the FCC matrix,which increases the hardness of the Al_(7)Cr_(20)Fe_(x)Ni_(73)−x(x=41−49)alloys.These results will help to the composition design and processing design of the Al−Cr−Fe−Ni based high-entropy alloys.
基金the National Natural Science Foundation of China(nos.32072309)Tianjin Municipal Science and Technology Committee(19JCYBJC27800).
文摘The article by Lan et al.[1],published on 30 October 2021 in Hepatology,showed the relationship between the natural flavonoid compound breviscapine and nonalcoholic steatohepatitis(NASH).The researchers demonstrated that breviscapine might be a novel therapeutic candidate for the treatment of NASH.It can be proven that breviscapine prevents metabolic stress-induced NASH progression through direct inhibition of the TGF-β-activated Kinase 1(TAK1)signaling pathway.
文摘Familial dysautonomia(FD,OMIM 223900;also known as HSAN III or Riley-Day syndrome) is the most prevalent form of hereditary sensory and autonomic neuropathy(HSAN;Axelrod et al., 1974). Patients suffering from autonomic and sensory nervous system impairment have no available effective treatment and the average age of death is approximately 24 years.
基金supported by the Fondo de Investigación Sanitaria(FIS)of Instituto de Salud Carlos III(Grant number PI12/2895 FEDER co-funded)
文摘Amyotrophic lateral sclerosis is a fatal neurodegenerative disorder characterized by upper and lower motor neuron degeneration, which leads to progressive paralysis of skeletal muscles and, ultimately, respiratory failure between 2–5 years after symptom onset. Unfortunately, currently accepted treatments for amyotrophic lateral sclerosis are extremely scarce and only provide modest benefit. As a consequence, a great effort is being done by the scientific community in order to achieve a better understanding of the different molecular and cellular processes that influence the progression and/or outcome of this neuropathological condition and, therefore, unravel new potential targets for therapeutic intervention. Interestingly, a growing number of experimental evidences have recently shown that, besides its well-known physiological roles in the developing and adult central nervous system, the Wnt family of proteins is involved in different neuropathologica conditions, including amyotrophic lateral sclerosis. These proteins are able to modulate, at least, three different signaling pathways, usually known as canonical(β-catenin dependent) and non-canonical(β-catenin independent) signaling pathways. In the present review, we aim to provide a general overview of the current knowledge that supports the relationship between the Wnt family of proteins and its associated signaling pathways and amyotrophic lateral sclerosis pathology, as well as their possible mechanisms of action. Altogether, the currently available knowledge suggests that Wnt signaling modulation might be a promising therapeutic approach to ameliorate the histopathological and functional deficits associated to amyotrophic lateral sclerosis, and thus improve the progression and outcome of this neuropathology.
基金Universiti Sains Malaysia for providing the fund for this study under RU grant No.1001/PBahan/8014105.
文摘Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in Al 1100 alloy has been studied in detail.Before subjecting to 50%cryorolling,samples were pre-annealed at 250℃ for 2 h and pre-solution treated at 540℃ for 1 h.X-ray diffraction and HRTEM techniques were used to understand the crystallite size,lattice strain and dislocation configuration in the processed alloy.The results indicate that the pre-annealed sample has the highest grain aspect ratio(4.43),the smallest crystallite size(37.53 nm),the highest lattice strain(9.12×10^(−3))and the highest dislocation density(45.16×10^(13) m^(−2))among the tested sample.The pre-annealed sample shows a significant improvement of 43.44%,24.64%and 20.33%in hardness,ultimate tensile strength and yield strength.Both pre-annealed and pre-solution treated samples show improved corrosion resistance when compared to cryorolled samples without any pre-treatment,with the pre-annealed sample showing the best corrosion resistance.