BACKGROUND The bone remodeling during orthodontic treatment for malocclusion often requires a long duration of around two to three years,which also may lead to some complications such as alveolar bone resorption or to...BACKGROUND The bone remodeling during orthodontic treatment for malocclusion often requires a long duration of around two to three years,which also may lead to some complications such as alveolar bone resorption or tooth root resorption.Low-intensity pulsed ultrasound(LIPUS),a noninvasive physical therapy,has been shown to promote bone fracture healing.It is also reported that LIPUS could reduce the duration of orthodontic treatment;however,how LIPUS regulates the bone metabolism during the orthodontic treatment process is still unclear.AIM To investigate the effects of LIPUS on bone remodeling in an orthodontic tooth movement(OTM)model and explore the underlying mechanisms.METHODS A rat model of OTM was established,and alveolar bone remodeling and tooth movement rate were evaluated via micro-computed tomography and staining of tissue sections.In vitro,human bone marrow mesenchymal stem cells(hBMSCs)were isolated to detect their osteogenic differentiation potential under compression and LIPUS stimulation by quantitative reverse transcription-polymerase chain reaction,Western blot,alkaline phosphatase(ALP)staining,and Alizarin red staining.The expression of Yes-associated protein(YAP1),the actin cytoskeleton,and the Lamin A/C nucleoskeleton were detected with or without YAP1 small interfering RNA(siRNA)application via immunofluorescence.RESULTS The force treatment inhibited the osteogenic differentiation potential of hBMSCs;moreover,the expression of osteogenesis markers,such as type 1 collagen(COL1),runt-related transcription factor 2,ALP,and osteocalcin(OCN),decreased.LIPUS could rescue the osteogenic differentiation of hBMSCs with increased expression of osteogenic marker inhibited by force.Mechanically,the expression of LaminA/C,F-actin,and YAP1 was downregulated after force treatment,which could be rescued by LIPUS.Moreover,the osteogenic differentiation of hBMSCs increased by LIPUS could be attenuated by YAP siRNA treatment.Consistently,LIPUS increased alveolar bone density and decreased vertical bone absorption in vivo.The decreased expression of COL1,OCN,and YAP1 on the compression side of the alveolar bone was partially rescued by LIPUS.CONCLUSION LIPUS can accelerate tooth movement and reduce alveolar bone resorption by modulating the cytoskeleton-Lamin A/C-YAP axis,which may be a promising strategy to reduce the orthodontic treatment process.展开更多
Reactive oxygen species are closely related to tumor development.In recent years,reactive oxygen species has become a hot spot in tumor therapy,and many natural substances in nature contain compound components with an...Reactive oxygen species are closely related to tumor development.In recent years,reactive oxygen species has become a hot spot in tumor therapy,and many natural substances in nature contain compound components with anti-tumor effects.However,there is a lack of discussion on the synergistic anti-tumor effects of natural products in combination with chemotherapeutic drugs through reactive oxygen species.The terms“natural products”,“reactive oxygen species”,“anti-tumor”,and“chemotherapy”were used to identify the synergistic effects of natural products.We conducted a systematic literature search in PubMed and Web of Science databases for relevant research articles and reviews published in recent years.We systematically summarized the studies related to anti-tumor active ingredients in natural compounds in the field of reactive oxygen species in recent years.A total of 77 relevant literatures were included.Among them,45 literatures containing various natural products such as terpenoids,flavonoids,alkaloids,etc.exert anti-tumor effects by regulating reactive oxygen species levels,and 32 literatures regarding adjunctive role of natural products in anti-tumor therapy.In this study,we found that natural products exert anti-tumor effects by elevating reactive oxygen species levels.It provides strong theoretical support for future clinical studies.展开更多
A new insulation packaging strategy for the stator windings of flat wire motors based on LTCC technology was studied for the first time.The study aimed to replace traditional plastic packaging methods and avoid aging ...A new insulation packaging strategy for the stator windings of flat wire motors based on LTCC technology was studied for the first time.The study aimed to replace traditional plastic packaging methods and avoid aging issues by fabricating a novel multilayer laminated Cu coil/CaO–Li_(2)O–B_(2)O_(3)–SiO_(2)glass-ceramic structure.The analysis of the interface microstructure of the laminated structure revealed that the CaO–Li_(2)O–B_(2)O_(3)–SiO_(2)glass-ceramic matrix consisted of a crystalline phase of CaSiO_(3)and an amorphous phase of SiO_(2).The interface between the Cu coil and CaO–Li_(2)O–B_(2)O_(3)–SiO_(2)glass-ceramic exhibited good bonding with no formation of secondary phases.Additionally,the strong bonding between the Cu coil and CaO–Li_(2)O–B_(2)O_(3)–SiO_(2)glass-ceramic was attributed to the diffusion of Cu atoms at the interface.The novel multilayer laminated structure based on LTCC technology proposed in this study can help achieve high-reliability insulation packaging for the stator windings of future high-power density and miniaturized flat wire motors.展开更多
Engineering the biosynthesis of plant-derived natural products in microbes presents several challenges, especially when the expression and activation of the plant cytochrome P450 enzyme is required. By recruiting two ...Engineering the biosynthesis of plant-derived natural products in microbes presents several challenges, especially when the expression and activation of the plant cytochrome P450 enzyme is required. By recruiting two enzymes—HpaB and HpaC—from several bacteria, we constructed functional 4- hydroxyphenylacetate 3-hydroxylase (4HPA3H) in Saccharomyces cerevisiae to take on a role similar to that of the plant-derived cytochrome P450 enzyme and produce caffeic acid. Along with a common tyrosine ammonia lyase (TAL), the different combinations of HpaB and HpaC presented varied capabilities in producing the target product, caffeic acid, from the substrate, L-tyrosine. The highest production of caffeic acid was obtained with the enzyme combination of HpaB from Pseudomonas aeruginosa and HpaC from Salmonella enterica, which yielded up to (289.4 ± 4.6) mg-L1 in shake-flask cultivation. The compatibility of heterologous enzymes within a yeast chassis was effectively improved, as the caffeic acid production was increased by 40 times from the initial yield. Six key amino acid residues around the flavin adenine dinucleotide (FAD) binding domain in HpaB from Pseudomonas aeruginosa were differentiate from those other HpaBs, and might play critical roles in affecting enzyme activity. We have thus established an effective approach to construct a highly efficient yeast system to synthesize non-native hydroxylated phenylpropanoids.展开更多
With the development of computer hardware technology and network technology,the Internet of Things as the extension and expansion of traditional computing network has played an increasingly important role in all profe...With the development of computer hardware technology and network technology,the Internet of Things as the extension and expansion of traditional computing network has played an increasingly important role in all professions and trades and has had a tremendous impact on people lifestyle.The information perception of the Internet of Things plays a key role as a link between the computer world and the real world.However,there are potential security threats in the Perceptual Layer Network applied for information perception because Perceptual Layer Network consists of a large number of sensor nodes with weak computing power,limited power supply,and open communication links.We proposed a novel lightweight authentication protocol based on password,smart card and biometric identification that achieves mutual authentication among User,GWN and sensor node.Biometric identification can increase the nonrepudiation feature that increases security.After security analysis and logical proof,the proposed protocol is proven to have a higher reliability and practicality.展开更多
Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor （HAuC14） to an electrolyzed aqueous solution of poly（N-vinylpyrrolidone） （PVP） and KN03, which indicates the good reducin...Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor （HAuC14） to an electrolyzed aqueous solution of poly（N-vinylpyrrolidone） （PVP） and KN03, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuC14,＇ respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H＋ or OH- catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.展开更多
Single-crystal GaN layers have been obtained by nitridingβ-Ga2O3 films in NH3 atmosphere.The effect of the temperature and time on the nitridation and conversion of Ga2O3 films have been investigated.The nitridation ...Single-crystal GaN layers have been obtained by nitridingβ-Ga2O3 films in NH3 atmosphere.The effect of the temperature and time on the nitridation and conversion of Ga2O3 films have been investigated.The nitridation process results in lots of holes in the surface of films.The higher nitridation temperature and longer time can promote the nitridation and improve the crystal quality of GaN films.The converted Ga N porous films show the single-crystal structures and lowstress,which can be used as templates for the epitaxial growth of high-quality GaN.展开更多
The removal of antibiotic pollutants remaining in the environmental media has been a big challenge nowadays.Herein,we report a facile and green approach to fabricate an eco-friendly composite membrane without addition...The removal of antibiotic pollutants remaining in the environmental media has been a big challenge nowadays.Herein,we report a facile and green approach to fabricate an eco-friendly composite membrane without addition of any toxic polymers or chemical cross-linking agents to effectively remove the tetracycline hydrochloride in Water.Firstly,the sulfated cellulose nanocrystalline(CNC) was obtained via hydrolysis of sulfuric acid by using microcrystalline cellulose(MCC) as raw material under ultrasonic condition.The as-prepared CNC has a nanowhisker dimension with 200.2 ± 110.2 nm in length,15.7 ± 9.3 nm in width,and 7.2 ± 3.1 nm in height.The obtained CNC is cellulose type I as determined by X-ray diffraction(XRD),while its crystallinity index(Crl) can reach 82.3%.Then,the composite membrane derived from the obtained CNC and commercial mixed cellulose ester(MCE)membrane was facilely prepared through vacuum dewatering process,which is applied to remove tetracycline hydrochloride(Th) in solution.The results showed that the removal efficiency of Th through the neat MCE was only28 ± 4%,while it could be improved to 58 ± 5% and 89 11%,respectively,by filtering through composite membranes with different contents of CNC deposition.Such effect is derived from the combine factors based on both steric hindrance(sieving) and electrostatic interaction(Donnan) effect of the composite membranes.The development of related CNC materials and composite fabrication processes is in favor of cost-effective and "green"polymer composites for the remediation of increasing antibiotic pollution and the purification of contaminated water nowadays.展开更多
Background:To facilitate the preparation of traditional Chinese medicines they are pre-mashed,i.e.,mashed in advance.However,storage conditions for pre-mashed traditional Chinese medicines are based on subjective judg...Background:To facilitate the preparation of traditional Chinese medicines they are pre-mashed,i.e.,mashed in advance.However,storage conditions for pre-mashed traditional Chinese medicines are based on subjective judgments of pharmacists,and the best storage conditions have not generally been determined.Semen Zizyphi Spinosae is a commonly used traditional Chinese medicine,and it is usually used after it is fried.The medicine needs to be mashed in a timely manner to ensure its effectiveness.The Chinese Pharmacopoeia provides a limit for its aflatoxin content.Methods:The orthogonal experimental design method optimizes the best plan for pre-mashed fried Semen Zizyphi Spinosae.Experimental conditions were defined using the L^(9)(3^(4))orthogonal design table.Four factors and three levels were used to study storage conditions.The four factors and three levels are as follows:storage temperature(10°C,20°C,and 30°C),storage humidity(45%,60%,and 75%),storage times(10,20 and 30 days),and particle sizes for the powder(coarsest,coarse and medium powders).The contents of jujuboside A,spinosin,aflatoxin B1,total aflatoxins(aflatoxins B1,B2,G1,and G2),moisture,total ash,acid value,and saponification values were measured.Results:The results demonstrated that the highest jujuboside A and spinosin contents were obtained using a storage temperature of 20°C,a storage humidity of 75%,a storage time of 10 days,and with a coarse powder particle size.Aflatoxin B1 and total aflatoxins(aflatoxins B1,B2,G1 and G2)were not detected under these conditions.Conclusion:There is no requirement for traditional Chinese medicines to be pre-mashed.This study evaluated various storage conditions for pre-mashed fried Semen Zizyphi Spinosae,and considered the influence of four factors on the contents of jujuboside A,spinolin and aflatoxin for quality control to provide a reference for other pre-mashed traditional Chinese medicines.展开更多
A bonding approach based on laser surface modification was developed to address the poor bonding be-tween Si_(3)N_(4) ceramic and Cu.The bonding mechanism in Si_(3)N_(4)/Cu heterogeneous composite structure fabricated...A bonding approach based on laser surface modification was developed to address the poor bonding be-tween Si_(3)N_(4) ceramic and Cu.The bonding mechanism in Si_(3)N_(4)/Cu heterogeneous composite structure fabricated by laser modification-assisted bonding is examined by means of scanning/transmission elec-tron microscopy and thermodynamic analysis.In the bonding process under laser modification,atomic intermixing at the interface is confirmed,as a result of the enhanced diffusion assisted by the dissocia-tion of Si_(3)N_(4) ceramic by laser.The dissociating Si precipitations on the surface,as well as the formation of micro-pores interfacial structure,would be the key concept of the bonding,by which the seamless and robust heterointerfaces were created.By controlling the laser-modifying conditions,we can obtain a reli-able heterostructure via the optimization of the trade-off of the surface structure and bonding strength,as determined by the laser-modified surface prior to bonding.The maximum structure depth and S ratio at the Si_(3)N_(4) surface were produced at a laser power of 56 W,corresponding to the maximal shear strength of 15.26 MPa.It is believed that the further development of this bonding technology will advance power electronic substrate fabrication applied in high-power devices.展开更多
Nano-Al2O3 particles modified Ag Cu Ni filler was adopted to braze the SiO2 ceramic and TC4.The effects of filler size as well as the brazing temperature on the interfacial microstructure and mechanical property of th...Nano-Al2O3 particles modified Ag Cu Ni filler was adopted to braze the SiO2 ceramic and TC4.The effects of filler size as well as the brazing temperature on the interfacial microstructure and mechanical property of the joints were investigated.Nanoscale filler reduced the phases dimension and promoted the homogeneous distribution of microstructure,obtaining a higher joint strength when compared to microscale filler.The increase of brazing temperature made the accelerating dissolution and diffusion of Ti,which promoted the increase of thickness of Ti4O7+TiSi2 layer adjacent to SiO2 ceramic and diffusion layer zone nearby TC4 alloy.The hypoeutectic structure was produced in the brazing seam due to the high Ti content.The maximum shear strength of^40 MPa was obtained at 950°C for 10 min.展开更多
Graphene nanosheets（GNSs） strengthened AgCuTi composite filler（AgCuTiG） was used to braze C/C composite and Ti-6Al-4V. The effects of GNSs on the wettability of AgCuTiG filler on the C/C composite surface and the ...Graphene nanosheets（GNSs） strengthened AgCuTi composite filler（AgCuTiG） was used to braze C/C composite and Ti-6Al-4V. The effects of GNSs on the wettability of AgCuTiG filler on the C/C composite surface and the interfacial microstructure and mechanical properties of brazed joints were investigated. The results indicate that the addition of GNSs reduced the wettability of AgCuTiG. The interfacial microstructure of brazed joints evolved with the addition of GNSs, where Ti3Cu4 and TiCu4 were converted to TiCu and the thickness of the reaction layer adjacent to the base material decreased. The maximum shear strength of joints brazed at 0.3 wt% GNSs was 23.3 MPa（880℃/10 min）. Further adding GNSs deteriorated the shear strength of the joints. Fracture of the joints occurred in the C/C composite substrate and the TiC layer adjacent to C/C composite.展开更多
A novel graphene reinforced BNi-2 composite filler was developed for brazing GH99 superalloy. The interracial microstructure of brazed joints was analyzed by field emission scanning electron microscope and a transmiss...A novel graphene reinforced BNi-2 composite filler was developed for brazing GH99 superalloy. The interracial microstructure of brazed joints was analyzed by field emission scanning electron microscope and a transmission electron microscope. The effects of graphene addition on the microstructure evolu-tion and mechanical properties of brazed joints were investigated, and the strengthening mechanism of graphene was analyzed. The results revealed that due to the addition of graphene, M23（C,B）6 compounds were synthesized in the y solid solution and brittle boride precipitates near the brazing seam decreased. Graphene was effective in retarding solute atoms diffusion thus impeding the precipitation of borides. Furthermore, the low coefficient of thermal expansion （CTE） of graphene was conducive to relieve stress concentration of the brazed joints during the cooling process. The shear strengths of brazed joints were significantly improved by exerting the strengthening effect of graphene. The maximum shear strengths of the brazed joints were 410.4 MPa and 329.7 MPa at room temperature and 800 ℃, respectively.展开更多
Metabolic engineering of heterologous resver- atrol production in Saccharomyces cerevisiae faces challenges as the precursor L-tyrosine is stringently regulated by a complex biosynthetic system. We over- expressed the...Metabolic engineering of heterologous resver- atrol production in Saccharomyces cerevisiae faces challenges as the precursor L-tyrosine is stringently regulated by a complex biosynthetic system. We over- expressed the main gene targets in the upstream pathways to investigate their influences on the downstream resver- atrol production. Single-gene overexpression and DNA assembly-directed multigene overexpression affect the production of resveratrol as well as its precursor p-coumaric acid. Finally, the collaboration of selected gene targets leads to an optimal resveratrol production of 66.144-3.74 mg.L-1, 2.27 times higher than the initial production in YPD medium （4% glucose）. The newly discovered gene targets TRP1 expressing phosphoribosy- lanthranilate isomerase, AR03 expressing 3-deoxy-D- arabino-heptulosonate-7-phosphate synthase, and 4CL expressing 4-coumaryl-CoA ligase show notable positive impacts on resveratrol production in S. cerevisiae.展开更多
Fatty alcohol biosynthesis by oleaginous microbes was a promising alternative to the petroleum or other non-renewable resources-based process. However, low titer and yield hamper the further industrial and commercial ...Fatty alcohol biosynthesis by oleaginous microbes was a promising alternative to the petroleum or other non-renewable resources-based process. However, low titer and yield hamper the further industrial and commercial applications. Here, we developed an efficient strategy to coordinate fatty alcohol with glycolysis which achieved a ‘pull-and-push’ effect to improve fatty alcohol production. Transcript profiling indicated that genes in carbohydrate metabolism were up-regulated significantly in response to high fatty alcohol production. Based on it, 11 glycolysis promoters were screening to express fatty acyl-CoA reductase(FAR) to relate the fatty alcohol production with the up-regulated carbohydrate metabolism, and the fatty alcohol production reached 557 mg/L when FAR was expressed by the promoter of PFBAin. RNA-seq and qRT-PCR analysis demonstrated that a ‘pull-and-push’ effect caused by the coordination system dynamically enhanced the product synthesis flux from top to bottom, which was also testified and intensified by doubled glucose concentration. After manipulating structural and regulatory genes of lipid metabolism, the final strain achieved up to 5.75 g/L fatty alcohol production from modified YPD medium(containing 91 g/L glucose) in shake flasks, which represented the highest titer reported to date. This work offered a feasible and effective reference for dynamic manipulation of fatty acid-derived chemicals synthesis.展开更多
Joining of ceramic and metal is a key component in microelectronic device manufacturing,in which the integrity of bonded interface is critical in the performance and stability of the devices.Current methods with a pro...Joining of ceramic and metal is a key component in microelectronic device manufacturing,in which the integrity of bonded interface is critical in the performance and stability of the devices.Current methods with a problem of thick transition layer at the interface impeded heat flow,which degraded device service life seriously.Herein,we propose a laser-assisted bonding approach to join ceramic to metal directly without any intermediate material.By focusing the laser on the surface of β-Si_(3)N_(4) ceramic,the Si microcrystalline layer with stacked α-Si_(3)N_(4) nanocrystals was prepared first.The face-centered cubic(fcc)Si and hexagonal close-packed(hcp)β-Si_(3)N_(4) substrate take the coherent orientation relations of[001]_(fcc)║[0001]_(hcp) and(220)_(fcc)║(10■0)_(hcp).Then,the defect-free Si_(3)N_(4)/Cu bonded interface obtained by the reaction of the formed Si and Cu at elevated temperature in the 805-900℃range for 30 min demonstrated a strong and stable joining of ceramic to metal.The introduction of the laser provides a novel approach to join ceramics to metals,and the ceramic/metal component is expected to be a new configuration for package substrate in high-power device applications.展开更多
OBJECTIVE:To evaluate the curative effect of external application of the Chinese drug,Sanjierupi Gao,on mastalgia caused by mammary gland hyperplasia.METHODS:This randomized,double-blinded,and placebo controlled study...OBJECTIVE:To evaluate the curative effect of external application of the Chinese drug,Sanjierupi Gao,on mastalgia caused by mammary gland hyperplasia.METHODS:This randomized,double-blinded,and placebo controlled study enrolled 260 patients with mammary gland hyperplasia from five hospitals.Patients were randomly and equally divided in-to a Sanjierupi Gao treatment group and a placebo control group.An adhesive plaster was applied to the most painful area on either breast for 7 h a day.Treatment lasted for two menstrual cycles without application during menstruation.Mastalgia was used as the main index of curative effect.The change before and after treatment in days of mastalgia,the time to alleviate pain,pain extent,and severe pain scores were observed.RESULTS:Compared to the control group,the treatment group had significantly fewer days of mastalgia(P<0.01),a significantly lower severe pain score(P<0.01),and significantly less subjective pain and tenderness(P<0.05 and P<0.01,respectively).Three days before the follow-up visit,the pain score in the treatment group was significantly lower than that in the control group(P<0.05).A non-parametric test was used to compare the time to alleviate mastalgia between the two groups and found no statistical difference(Z=0.313,P=0.754).CONCLUSION:Application of Sanjierupi Gao can decrease mastalgia duration in patients with mammary gland hyperplasia during menstruation and alleviate the extent of mastalgia.The time to alleviate pain is psychologically influenced.展开更多
AgCuTi-based composite fillers reinforced with Carbon Nanotubes(CNTs) were prepared by mechanical ball milling and ultrasonic agitation. The morphological features, chemical components, and melting characteristics of ...AgCuTi-based composite fillers reinforced with Carbon Nanotubes(CNTs) were prepared by mechanical ball milling and ultrasonic agitation. The morphological features, chemical components, and melting characteristics of the composite fillers with different content of CNTs addition were investigated using Field Emission Scanning Electron Microscopy(FESEM), XRay Diffraction(XRD) and a Differential Scanning Calorimeter(DSC). After being heated at 900 ℃, the microstructure of the composite fillers was examined through FESEM and Transmission Electron Microscopy(TEM) to analyze the interfacial characteristics in the AgCuTi-CNTs system.The microstructures of the composite fillers with 0.5 wt% CNTs and 0.1 wt% CNTs were compared. It was found that 0.5 wt% CNTs were favorable for dispersive distribution of the structure.Nano-sized TiC particles formed in the reaction of CNTs with Ti, resulting in the transformation of TiCu;with high Ti content and Ti;Cu;phases to TiCu;phase with low Ti content. Additionally,the microstructure evolution of the composite fillers was studied by changing the ratio of Ti/CNTs.Results showed that CNTs significantly influenced the wettability of the AgCuTi filler. After addition of 0.3 wt% of CNTs, the spreading area of the composite filler on the C/C composite increased by 146.0%.展开更多
The effect of Carbon Nanotubes(CNTs)content on the wettability of AgCu-4.5Ti+x CNTs(wt%)composite filler alloys on C/C composite was investigated.The results show that the added CNTs reacted with element Ti in the fil...The effect of Carbon Nanotubes(CNTs)content on the wettability of AgCu-4.5Ti+x CNTs(wt%)composite filler alloys on C/C composite was investigated.The results show that the added CNTs reacted with element Ti in the filler and produced the dispersed fine in situ synthesized TiC particles,which increased the consumption of element Ti and provided the nucleus for the growth of Ti-Cu compounds simultaneously.The above effects of introducing CNTs,inhibited the formation of Ti-Cu compounds,also changed the distribution of compounds,which dramatically influenced the interfacial microstructure and characteristics of wetting behavior.The increase of CNTs content refined and dispersed coarse Ti-Cu compounds,decreased the initial spreading temperature,and improved the wettability,but high content of CNTs(more than 0.3 wt%)decreased the wettability of the filler alloy.The wetting interfacial microstructure of corresponding composite filler alloys were analyzed by Scanning Electron Microscope(SEM),Energy Dispersive X-ray Spectrometer(EDS)and Transmission Electron Microscope(TEM),which consisted of TiC,TiCu,TiCu;and TiCu;compound.The typical wetting behavior of AgCu-4.5Ti+0.3wt%CNTs composite filler on C/C composite was divided into four stages.The effect mechanism of CNTs content on the wetting behavior was proposed.展开更多
基金Supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China,No.2022YFA1105800the National Natural Science Foundation of China,No.81970940.
文摘BACKGROUND The bone remodeling during orthodontic treatment for malocclusion often requires a long duration of around two to three years,which also may lead to some complications such as alveolar bone resorption or tooth root resorption.Low-intensity pulsed ultrasound(LIPUS),a noninvasive physical therapy,has been shown to promote bone fracture healing.It is also reported that LIPUS could reduce the duration of orthodontic treatment;however,how LIPUS regulates the bone metabolism during the orthodontic treatment process is still unclear.AIM To investigate the effects of LIPUS on bone remodeling in an orthodontic tooth movement(OTM)model and explore the underlying mechanisms.METHODS A rat model of OTM was established,and alveolar bone remodeling and tooth movement rate were evaluated via micro-computed tomography and staining of tissue sections.In vitro,human bone marrow mesenchymal stem cells(hBMSCs)were isolated to detect their osteogenic differentiation potential under compression and LIPUS stimulation by quantitative reverse transcription-polymerase chain reaction,Western blot,alkaline phosphatase(ALP)staining,and Alizarin red staining.The expression of Yes-associated protein(YAP1),the actin cytoskeleton,and the Lamin A/C nucleoskeleton were detected with or without YAP1 small interfering RNA(siRNA)application via immunofluorescence.RESULTS The force treatment inhibited the osteogenic differentiation potential of hBMSCs;moreover,the expression of osteogenesis markers,such as type 1 collagen(COL1),runt-related transcription factor 2,ALP,and osteocalcin(OCN),decreased.LIPUS could rescue the osteogenic differentiation of hBMSCs with increased expression of osteogenic marker inhibited by force.Mechanically,the expression of LaminA/C,F-actin,and YAP1 was downregulated after force treatment,which could be rescued by LIPUS.Moreover,the osteogenic differentiation of hBMSCs increased by LIPUS could be attenuated by YAP siRNA treatment.Consistently,LIPUS increased alveolar bone density and decreased vertical bone absorption in vivo.The decreased expression of COL1,OCN,and YAP1 on the compression side of the alveolar bone was partially rescued by LIPUS.CONCLUSION LIPUS can accelerate tooth movement and reduce alveolar bone resorption by modulating the cytoskeleton-Lamin A/C-YAP axis,which may be a promising strategy to reduce the orthodontic treatment process.
基金supported by National Natural Science Foundation of China(No.82003775)Talent Project established by Chinese Pharmaceutical Association Hospital Phamacy department.(No.CPA-Z05-ZC-2023-003)+2 种基金Outstanding Young Scholars Foundation of Harbin Medical University Cancer Hospital(No.JCQN2021-04)Heilongjiang Province postdoctoral research fund(No.LBH-Q20050)Special fund for clinical and basic research of medical research development fund(No.YXKY-WS013G).
文摘Reactive oxygen species are closely related to tumor development.In recent years,reactive oxygen species has become a hot spot in tumor therapy,and many natural substances in nature contain compound components with anti-tumor effects.However,there is a lack of discussion on the synergistic anti-tumor effects of natural products in combination with chemotherapeutic drugs through reactive oxygen species.The terms“natural products”,“reactive oxygen species”,“anti-tumor”,and“chemotherapy”were used to identify the synergistic effects of natural products.We conducted a systematic literature search in PubMed and Web of Science databases for relevant research articles and reviews published in recent years.We systematically summarized the studies related to anti-tumor active ingredients in natural compounds in the field of reactive oxygen species in recent years.A total of 77 relevant literatures were included.Among them,45 literatures containing various natural products such as terpenoids,flavonoids,alkaloids,etc.exert anti-tumor effects by regulating reactive oxygen species levels,and 32 literatures regarding adjunctive role of natural products in anti-tumor therapy.In this study,we found that natural products exert anti-tumor effects by elevating reactive oxygen species levels.It provides strong theoretical support for future clinical studies.
基金supported by National Natural Science Foundation of China(grant Nos.51875130 and 52175307)Shandong Provincial Natural Science Foundation of China(No.ZR2019MEE091)the Taishan Scholars Foundation of Shandong Province(No.tsqn201812128)。
文摘A new insulation packaging strategy for the stator windings of flat wire motors based on LTCC technology was studied for the first time.The study aimed to replace traditional plastic packaging methods and avoid aging issues by fabricating a novel multilayer laminated Cu coil/CaO–Li_(2)O–B_(2)O_(3)–SiO_(2)glass-ceramic structure.The analysis of the interface microstructure of the laminated structure revealed that the CaO–Li_(2)O–B_(2)O_(3)–SiO_(2)glass-ceramic matrix consisted of a crystalline phase of CaSiO_(3)and an amorphous phase of SiO_(2).The interface between the Cu coil and CaO–Li_(2)O–B_(2)O_(3)–SiO_(2)glass-ceramic exhibited good bonding with no formation of secondary phases.Additionally,the strong bonding between the Cu coil and CaO–Li_(2)O–B_(2)O_(3)–SiO_(2)glass-ceramic was attributed to the diffusion of Cu atoms at the interface.The novel multilayer laminated structure based on LTCC technology proposed in this study can help achieve high-reliability insulation packaging for the stator windings of future high-power density and miniaturized flat wire motors.
基金the Ministry of Science and Technology of China (2014CB745100)the National Natural Science Foundation of China (21390203 and 21706186).
文摘Engineering the biosynthesis of plant-derived natural products in microbes presents several challenges, especially when the expression and activation of the plant cytochrome P450 enzyme is required. By recruiting two enzymes—HpaB and HpaC—from several bacteria, we constructed functional 4- hydroxyphenylacetate 3-hydroxylase (4HPA3H) in Saccharomyces cerevisiae to take on a role similar to that of the plant-derived cytochrome P450 enzyme and produce caffeic acid. Along with a common tyrosine ammonia lyase (TAL), the different combinations of HpaB and HpaC presented varied capabilities in producing the target product, caffeic acid, from the substrate, L-tyrosine. The highest production of caffeic acid was obtained with the enzyme combination of HpaB from Pseudomonas aeruginosa and HpaC from Salmonella enterica, which yielded up to (289.4 ± 4.6) mg-L1 in shake-flask cultivation. The compatibility of heterologous enzymes within a yeast chassis was effectively improved, as the caffeic acid production was increased by 40 times from the initial yield. Six key amino acid residues around the flavin adenine dinucleotide (FAD) binding domain in HpaB from Pseudomonas aeruginosa were differentiate from those other HpaBs, and might play critical roles in affecting enzyme activity. We have thus established an effective approach to construct a highly efficient yeast system to synthesize non-native hydroxylated phenylpropanoids.
基金This work is supported by the National Science Foundation of China(Grant No.61501132,Grant Nos.61771154,61301095,61370084)the China Postdoctoral Science Foundation No.2016M591515+1 种基金the Heilongjiang Postdoctoral Sustentation Fund with No.LBH-Z14055Harbin Application Technology Research and Development Project(Grant Nos.2016RAQXJ063,2016RAXXJ013).
文摘With the development of computer hardware technology and network technology,the Internet of Things as the extension and expansion of traditional computing network has played an increasingly important role in all professions and trades and has had a tremendous impact on people lifestyle.The information perception of the Internet of Things plays a key role as a link between the computer world and the real world.However,there are potential security threats in the Perceptual Layer Network applied for information perception because Perceptual Layer Network consists of a large number of sensor nodes with weak computing power,limited power supply,and open communication links.We proposed a novel lightweight authentication protocol based on password,smart card and biometric identification that achieves mutual authentication among User,GWN and sensor node.Biometric identification can increase the nonrepudiation feature that increases security.After security analysis and logical proof,the proposed protocol is proven to have a higher reliability and practicality.
基金supported by the National Natural Science Foundation of China(No.21073111)the Natural Science Foundation of Shandong Province,China(No.ZR2010BQ029)
文摘Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor （HAuC14） to an electrolyzed aqueous solution of poly（N-vinylpyrrolidone） （PVP） and KN03, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuC14,＇ respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H＋ or OH- catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFB0404201)the Six-Talent Peaks Project in Jiangsu Province,China(Grant No.XCL-107)+2 种基金the State Key Research and Development Program of Jiangsu Province,China(Grant No.BE2018115)the Fund from the Solid-state Lighting and Energy-saving Electronics Collaborative Innovation Center,PAPDthe Fund from the State Grid Shandong Electric Power Company
文摘Single-crystal GaN layers have been obtained by nitridingβ-Ga2O3 films in NH3 atmosphere.The effect of the temperature and time on the nitridation and conversion of Ga2O3 films have been investigated.The nitridation process results in lots of holes in the surface of films.The higher nitridation temperature and longer time can promote the nitridation and improve the crystal quality of GaN films.The converted Ga N porous films show the single-crystal structures and lowstress,which can be used as templates for the epitaxial growth of high-quality GaN.
基金financially supported by the Tianjin Science and Technology Committee Major Project Program(18ZXJMTG00070)
文摘The removal of antibiotic pollutants remaining in the environmental media has been a big challenge nowadays.Herein,we report a facile and green approach to fabricate an eco-friendly composite membrane without addition of any toxic polymers or chemical cross-linking agents to effectively remove the tetracycline hydrochloride in Water.Firstly,the sulfated cellulose nanocrystalline(CNC) was obtained via hydrolysis of sulfuric acid by using microcrystalline cellulose(MCC) as raw material under ultrasonic condition.The as-prepared CNC has a nanowhisker dimension with 200.2 ± 110.2 nm in length,15.7 ± 9.3 nm in width,and 7.2 ± 3.1 nm in height.The obtained CNC is cellulose type I as determined by X-ray diffraction(XRD),while its crystallinity index(Crl) can reach 82.3%.Then,the composite membrane derived from the obtained CNC and commercial mixed cellulose ester(MCE)membrane was facilely prepared through vacuum dewatering process,which is applied to remove tetracycline hydrochloride(Th) in solution.The results showed that the removal efficiency of Th through the neat MCE was only28 ± 4%,while it could be improved to 58 ± 5% and 89 11%,respectively,by filtering through composite membranes with different contents of CNC deposition.Such effect is derived from the combine factors based on both steric hindrance(sieving) and electrostatic interaction(Donnan) effect of the composite membranes.The development of related CNC materials and composite fabrication processes is in favor of cost-effective and "green"polymer composites for the remediation of increasing antibiotic pollution and the purification of contaminated water nowadays.
基金This work was supported by the Shanghai Municipal Commission of Health and Family Planning(No.20174Y0034)the Third batch of specialized subject construction of traditional Chinese medicine in Jiading District-Traditional Chinese Medicine(No.2020-JDZYYZDXK-01).
文摘Background:To facilitate the preparation of traditional Chinese medicines they are pre-mashed,i.e.,mashed in advance.However,storage conditions for pre-mashed traditional Chinese medicines are based on subjective judgments of pharmacists,and the best storage conditions have not generally been determined.Semen Zizyphi Spinosae is a commonly used traditional Chinese medicine,and it is usually used after it is fried.The medicine needs to be mashed in a timely manner to ensure its effectiveness.The Chinese Pharmacopoeia provides a limit for its aflatoxin content.Methods:The orthogonal experimental design method optimizes the best plan for pre-mashed fried Semen Zizyphi Spinosae.Experimental conditions were defined using the L^(9)(3^(4))orthogonal design table.Four factors and three levels were used to study storage conditions.The four factors and three levels are as follows:storage temperature(10°C,20°C,and 30°C),storage humidity(45%,60%,and 75%),storage times(10,20 and 30 days),and particle sizes for the powder(coarsest,coarse and medium powders).The contents of jujuboside A,spinosin,aflatoxin B1,total aflatoxins(aflatoxins B1,B2,G1,and G2),moisture,total ash,acid value,and saponification values were measured.Results:The results demonstrated that the highest jujuboside A and spinosin contents were obtained using a storage temperature of 20°C,a storage humidity of 75%,a storage time of 10 days,and with a coarse powder particle size.Aflatoxin B1 and total aflatoxins(aflatoxins B1,B2,G1 and G2)were not detected under these conditions.Conclusion:There is no requirement for traditional Chinese medicines to be pre-mashed.This study evaluated various storage conditions for pre-mashed fried Semen Zizyphi Spinosae,and considered the influence of four factors on the contents of jujuboside A,spinolin and aflatoxin for quality control to provide a reference for other pre-mashed traditional Chinese medicines.
基金supported by the National Natural Science Foun-dation of China(grant Nos.52275318 and 52175307)Taishan Scholars Foundation of Shandong Province(No.tsqn201812128)+1 种基金Shandong Natural Science Foundation(Nos.ZR2023JQ021 and ZR2023QE221)China Academy of Space Technology Innovation Foundation(No.CAST2022).
文摘A bonding approach based on laser surface modification was developed to address the poor bonding be-tween Si_(3)N_(4) ceramic and Cu.The bonding mechanism in Si_(3)N_(4)/Cu heterogeneous composite structure fabricated by laser modification-assisted bonding is examined by means of scanning/transmission elec-tron microscopy and thermodynamic analysis.In the bonding process under laser modification,atomic intermixing at the interface is confirmed,as a result of the enhanced diffusion assisted by the dissocia-tion of Si_(3)N_(4) ceramic by laser.The dissociating Si precipitations on the surface,as well as the formation of micro-pores interfacial structure,would be the key concept of the bonding,by which the seamless and robust heterointerfaces were created.By controlling the laser-modifying conditions,we can obtain a reli-able heterostructure via the optimization of the trade-off of the surface structure and bonding strength,as determined by the laser-modified surface prior to bonding.The maximum structure depth and S ratio at the Si_(3)N_(4) surface were produced at a laser power of 56 W,corresponding to the maximal shear strength of 15.26 MPa.It is believed that the further development of this bonding technology will advance power electronic substrate fabrication applied in high-power devices.
基金supported by National Natural Science Foundation of China(Grant Nos.51505105,51875130 and 51775138)the Key Research&Development Program of Shandong Province(No.2017GGX40103).
文摘Nano-Al2O3 particles modified Ag Cu Ni filler was adopted to braze the SiO2 ceramic and TC4.The effects of filler size as well as the brazing temperature on the interfacial microstructure and mechanical property of the joints were investigated.Nanoscale filler reduced the phases dimension and promoted the homogeneous distribution of microstructure,obtaining a higher joint strength when compared to microscale filler.The increase of brazing temperature made the accelerating dissolution and diffusion of Ti,which promoted the increase of thickness of Ti4O7+TiSi2 layer adjacent to SiO2 ceramic and diffusion layer zone nearby TC4 alloy.The hypoeutectic structure was produced in the brazing seam due to the high Ti content.The maximum shear strength of^40 MPa was obtained at 950°C for 10 min.
基金supports to this study from the National Natural Science Foundation of China–China (Nos.51505105 and 51775138)the Natural Science Foundation of Shandong Province–China (No.ZR2014EEQ001)the International Science & Technology Cooperation Program of China–China (No.2015DFA50470)
文摘Graphene nanosheets（GNSs） strengthened AgCuTi composite filler（AgCuTiG） was used to braze C/C composite and Ti-6Al-4V. The effects of GNSs on the wettability of AgCuTiG filler on the C/C composite surface and the interfacial microstructure and mechanical properties of brazed joints were investigated. The results indicate that the addition of GNSs reduced the wettability of AgCuTiG. The interfacial microstructure of brazed joints evolved with the addition of GNSs, where Ti3Cu4 and TiCu4 were converted to TiCu and the thickness of the reaction layer adjacent to the base material decreased. The maximum shear strength of joints brazed at 0.3 wt% GNSs was 23.3 MPa（880℃/10 min）. Further adding GNSs deteriorated the shear strength of the joints. Fracture of the joints occurred in the C/C composite substrate and the TiC layer adjacent to C/C composite.
基金supported financially by the National Natural Science Foundation of China(Nos.51505105,51775138 and U1537206)the International Science&Technology Cooperation Program of China(No.2015DFA50470)the Key Research&Development program of Shandong Province(No.2017GGX40103)
文摘A novel graphene reinforced BNi-2 composite filler was developed for brazing GH99 superalloy. The interracial microstructure of brazed joints was analyzed by field emission scanning electron microscope and a transmission electron microscope. The effects of graphene addition on the microstructure evolu-tion and mechanical properties of brazed joints were investigated, and the strengthening mechanism of graphene was analyzed. The results revealed that due to the addition of graphene, M23（C,B）6 compounds were synthesized in the y solid solution and brittle boride precipitates near the brazing seam decreased. Graphene was effective in retarding solute atoms diffusion thus impeding the precipitation of borides. Furthermore, the low coefficient of thermal expansion （CTE） of graphene was conducive to relieve stress concentration of the brazed joints during the cooling process. The shear strengths of brazed joints were significantly improved by exerting the strengthening effect of graphene. The maximum shear strengths of the brazed joints were 410.4 MPa and 329.7 MPa at room temperature and 800 ℃, respectively.
基金The authors declare no competing financial interest. This work was funded by the National Basic Research Program of China （973 Program, Grant No. 2014CB745100） and the National High Technology Research and Development Program of China （863 Program, Grant No. 2012AA02AT01）, the International S＆T Cooperation Program of China （2015DFA00960）, and the National Natural Science Foundation of China （Major Program, Grant No. 21390203）.
文摘Metabolic engineering of heterologous resver- atrol production in Saccharomyces cerevisiae faces challenges as the precursor L-tyrosine is stringently regulated by a complex biosynthetic system. We over- expressed the main gene targets in the upstream pathways to investigate their influences on the downstream resver- atrol production. Single-gene overexpression and DNA assembly-directed multigene overexpression affect the production of resveratrol as well as its precursor p-coumaric acid. Finally, the collaboration of selected gene targets leads to an optimal resveratrol production of 66.144-3.74 mg.L-1, 2.27 times higher than the initial production in YPD medium （4% glucose）. The newly discovered gene targets TRP1 expressing phosphoribosy- lanthranilate isomerase, AR03 expressing 3-deoxy-D- arabino-heptulosonate-7-phosphate synthase, and 4CL expressing 4-coumaryl-CoA ligase show notable positive impacts on resveratrol production in S. cerevisiae.
基金supported by the National Natural Science Foundation of China (21621004)Young Elite Scientists Sponsorship Program by Tianjin (TJSQNTJ-2018-16)
文摘Fatty alcohol biosynthesis by oleaginous microbes was a promising alternative to the petroleum or other non-renewable resources-based process. However, low titer and yield hamper the further industrial and commercial applications. Here, we developed an efficient strategy to coordinate fatty alcohol with glycolysis which achieved a ‘pull-and-push’ effect to improve fatty alcohol production. Transcript profiling indicated that genes in carbohydrate metabolism were up-regulated significantly in response to high fatty alcohol production. Based on it, 11 glycolysis promoters were screening to express fatty acyl-CoA reductase(FAR) to relate the fatty alcohol production with the up-regulated carbohydrate metabolism, and the fatty alcohol production reached 557 mg/L when FAR was expressed by the promoter of PFBAin. RNA-seq and qRT-PCR analysis demonstrated that a ‘pull-and-push’ effect caused by the coordination system dynamically enhanced the product synthesis flux from top to bottom, which was also testified and intensified by doubled glucose concentration. After manipulating structural and regulatory genes of lipid metabolism, the final strain achieved up to 5.75 g/L fatty alcohol production from modified YPD medium(containing 91 g/L glucose) in shake flasks, which represented the highest titer reported to date. This work offered a feasible and effective reference for dynamic manipulation of fatty acid-derived chemicals synthesis.
基金supported by National Natural Science Foundation of China (grant Nos.51875130 and 51775138)Shandong Provincial Natural Science Foundation of China (No.ZR2019MEE091)
文摘Joining of ceramic and metal is a key component in microelectronic device manufacturing,in which the integrity of bonded interface is critical in the performance and stability of the devices.Current methods with a problem of thick transition layer at the interface impeded heat flow,which degraded device service life seriously.Herein,we propose a laser-assisted bonding approach to join ceramic to metal directly without any intermediate material.By focusing the laser on the surface of β-Si_(3)N_(4) ceramic,the Si microcrystalline layer with stacked α-Si_(3)N_(4) nanocrystals was prepared first.The face-centered cubic(fcc)Si and hexagonal close-packed(hcp)β-Si_(3)N_(4) substrate take the coherent orientation relations of[001]_(fcc)║[0001]_(hcp) and(220)_(fcc)║(10■0)_(hcp).Then,the defect-free Si_(3)N_(4)/Cu bonded interface obtained by the reaction of the formed Si and Cu at elevated temperature in the 805-900℃range for 30 min demonstrated a strong and stable joining of ceramic to metal.The introduction of the laser provides a novel approach to join ceramics to metals,and the ceramic/metal component is expected to be a new configuration for package substrate in high-power device applications.
基金Supported by a Demonstrative Project of Research into Specific Therapy and Technology of External Application in Traditional Chinese MedicineNational Sci-Tech Plan of the Ministry of Science and Technology in the 11th 5-Year Plan(2008BAI53B053)
文摘OBJECTIVE:To evaluate the curative effect of external application of the Chinese drug,Sanjierupi Gao,on mastalgia caused by mammary gland hyperplasia.METHODS:This randomized,double-blinded,and placebo controlled study enrolled 260 patients with mammary gland hyperplasia from five hospitals.Patients were randomly and equally divided in-to a Sanjierupi Gao treatment group and a placebo control group.An adhesive plaster was applied to the most painful area on either breast for 7 h a day.Treatment lasted for two menstrual cycles without application during menstruation.Mastalgia was used as the main index of curative effect.The change before and after treatment in days of mastalgia,the time to alleviate pain,pain extent,and severe pain scores were observed.RESULTS:Compared to the control group,the treatment group had significantly fewer days of mastalgia(P<0.01),a significantly lower severe pain score(P<0.01),and significantly less subjective pain and tenderness(P<0.05 and P<0.01,respectively).Three days before the follow-up visit,the pain score in the treatment group was significantly lower than that in the control group(P<0.05).A non-parametric test was used to compare the time to alleviate mastalgia between the two groups and found no statistical difference(Z=0.313,P=0.754).CONCLUSION:Application of Sanjierupi Gao can decrease mastalgia duration in patients with mammary gland hyperplasia during menstruation and alleviate the extent of mastalgia.The time to alleviate pain is psychologically influenced.
基金co-funded by the National Natural Science Foundation of China(Nos.51875130 and 51775138)the Shandong Provincial Natural Science Foundation of China(No.ZR2019MEE091)。
文摘AgCuTi-based composite fillers reinforced with Carbon Nanotubes(CNTs) were prepared by mechanical ball milling and ultrasonic agitation. The morphological features, chemical components, and melting characteristics of the composite fillers with different content of CNTs addition were investigated using Field Emission Scanning Electron Microscopy(FESEM), XRay Diffraction(XRD) and a Differential Scanning Calorimeter(DSC). After being heated at 900 ℃, the microstructure of the composite fillers was examined through FESEM and Transmission Electron Microscopy(TEM) to analyze the interfacial characteristics in the AgCuTi-CNTs system.The microstructures of the composite fillers with 0.5 wt% CNTs and 0.1 wt% CNTs were compared. It was found that 0.5 wt% CNTs were favorable for dispersive distribution of the structure.Nano-sized TiC particles formed in the reaction of CNTs with Ti, resulting in the transformation of TiCu;with high Ti content and Ti;Cu;phases to TiCu;phase with low Ti content. Additionally,the microstructure evolution of the composite fillers was studied by changing the ratio of Ti/CNTs.Results showed that CNTs significantly influenced the wettability of the AgCuTi filler. After addition of 0.3 wt% of CNTs, the spreading area of the composite filler on the C/C composite increased by 146.0%.
基金supported by National Natural Science Foundation of China(Nos.51875130 and 51775138)Natural Science Foundation of Shandong Province,China(No.ZR2019MEE091)。
文摘The effect of Carbon Nanotubes(CNTs)content on the wettability of AgCu-4.5Ti+x CNTs(wt%)composite filler alloys on C/C composite was investigated.The results show that the added CNTs reacted with element Ti in the filler and produced the dispersed fine in situ synthesized TiC particles,which increased the consumption of element Ti and provided the nucleus for the growth of Ti-Cu compounds simultaneously.The above effects of introducing CNTs,inhibited the formation of Ti-Cu compounds,also changed the distribution of compounds,which dramatically influenced the interfacial microstructure and characteristics of wetting behavior.The increase of CNTs content refined and dispersed coarse Ti-Cu compounds,decreased the initial spreading temperature,and improved the wettability,but high content of CNTs(more than 0.3 wt%)decreased the wettability of the filler alloy.The wetting interfacial microstructure of corresponding composite filler alloys were analyzed by Scanning Electron Microscope(SEM),Energy Dispersive X-ray Spectrometer(EDS)and Transmission Electron Microscope(TEM),which consisted of TiC,TiCu,TiCu;and TiCu;compound.The typical wetting behavior of AgCu-4.5Ti+0.3wt%CNTs composite filler on C/C composite was divided into four stages.The effect mechanism of CNTs content on the wetting behavior was proposed.
