Based on optofluidics and whispering gallery mode(WGM)theory,here an optofluidic refractive index sensor with microtube-coupled suspended core fiber(SCF)is proposed.It solves the issues of general sensors with microca...Based on optofluidics and whispering gallery mode(WGM)theory,here an optofluidic refractive index sensor with microtube-coupled suspended core fiber(SCF)is proposed.It solves the issues of general sensors with microcavity-coupled fiber taper such as too fragile,unstable performance due to open coupling,poor portability and repeatability,while overcoming the poor performance of low refractive index sensing in general full-package fiber sensors.The sensor only needs a very small amount of liquid sample(about 1.8 nL).The proposed sensor combines the excellent performance of full package,optofluidics and WGM resonator.The resonant characteristics and sensing performance of the sensor are analyzed and discussed by the theoretical simulation.The simulation results indicate that the sensor has a wide refractive index sensing range(1.330-1.700)and good performance.The resonance wavelength shift has a good linear relationship with the liquid refractive index variation.In the low refractive index region,the sensitivity is 222.5-247.5 nm/RIU,Q-factor is 1.03×10^(3) and the detection limit is 3.64×10^(-4) RIU.In the medium and high refractive index regions,the sensitivity is 564.4-846.2 nm/RIU,Q-factor is up to 8.62×10^(4),and the detection limit can be as low as 1.29×10^(-6) RIU.The sensor exhibits a high sensitivity,a high Q-factor and a very low detection limit.展开更多
The degradation of Mg alloys relates to the service performance of Mg alloy biodegradable implants.In order to investigate the degradation behavior of Mg alloys as vascular stent materials in the near service environm...The degradation of Mg alloys relates to the service performance of Mg alloy biodegradable implants.In order to investigate the degradation behavior of Mg alloys as vascular stent materials in the near service environment,the hot-extruded fine-grained Mg-Zn-Y-Nd alloy microtubes,which are employed to manufacture vascular stents,were tested under radial compressive stress in the dynamic Hanks'Balanced Salt Solution(HBSS).The results revealed that the high flow rate accelerates the degradation of Mg alloy microtubes and its degradation is sensitive to radial compressive stress.These results contribute to understanding the service performance of Mg alloys as vascular stent materials.展开更多
This paper reports that pure hexagonal aluminium nitride microtubes and nanowires growing along the [0001] direction have been successfully synthesized by directly reacting AlCl3 with NaN3 at low temperature （450℃）...This paper reports that pure hexagonal aluminium nitride microtubes and nanowires growing along the [0001] direction have been successfully synthesized by directly reacting AlCl3 with NaN3 at low temperature （450℃） under condition of non-solvent system. The grey-white powder of reacting product was characterized by high-resolution transmission electron microscope （HRTEM）, which shows that the powder is long straight-wire morphology with outer diameter from 40nm to 300 nm and length up to several micrometres. The results of both electron diffraction （ED） and x-ray diffraction （XRD） indicate that the AlN microtubes have a pure hexagonal monocrystal tubular structure with the combination of the curled AlN nanobelts. Room-temperature photoluminescence spectrum of the synthesized sample showed an emission peak, which is closely related to the small size of the microtubes.展开更多
A newly natural fine template, kapok fiber, for microtube preparation was reported. Large scale microtubes with high length/diameter ratio and controllable wall thickness and morphology have been successfully fabricat...A newly natural fine template, kapok fiber, for microtube preparation was reported. Large scale microtubes with high length/diameter ratio and controllable wall thickness and morphology have been successfully fabricated with this template. It is a wildly available, low-cost, environmental friendly and fine structured natural template for microtubes. Its thin wall thickness is only about 1-2 um that means the whole template material is tiny and easy for removing. Even there is any residue the amount can be ignored. When the template is covered with a shell component, hollow structured microtube could be obtained by removing the thin inner template, and its shape could be the same as that of the original template （positive copy of the template＇s shape）. The products have high length/diameter ratio and uniform tubular structure. By further modifying the fabricating methods, facile fabrication not only exists for polypyrrole （PPy） in electrochemical deposition, but also for many other organic and inorganic materials. The surface morphology and wall thickness of the resultant microtubes can be easily modulated by controlling the processing conditions. This natural fiber is predicted to be a fine template for fabricating large scale microtubes with large cavity and high length/diameter ratio.展开更多
With the detoxicated seedling of a potato cultivation breed named “Mire” as the material, the effect of auxins CCC, 6-BA, and active carbon to microtubers of potato (Solanum tubersum L.) was investigated under the i...With the detoxicated seedling of a potato cultivation breed named “Mire” as the material, the effect of auxins CCC, 6-BA, and active carbon to microtubers of potato (Solanum tubersum L.) was investigated under the in-vitro circumstances. The result indicated the exogenous auxins improved the production and quality of microtubers of potatoes. The effect of induction can be described as CCC > CCC + 6-BA > 6-BA > CK, the number of microtubers in per flask is 8.17 > 7.67 > 7.29 > 5.46, and the number of large potatoes in per flask is 6.33 > 5.17 > 3.17 > 1. In addition, by adding 0.5‰ of active charcoal, the growth period was shortened from 25.0 days to 9.33 days on average, and the amount of larger potatoes increased 8.54%. These results benefited the growth of microtubers of potato.展开更多
For efficient solar energy conversion,the morphology engineering of hollow graphitic carbon nitride(gC3 N4)is one of the promising approachs benefiting from abundant exposed active sites and short photocarrier transpo...For efficient solar energy conversion,the morphology engineering of hollow graphitic carbon nitride(gC3 N4)is one of the promising approachs benefiting from abundant exposed active sites and short photocarrier transport distances,but is difficult to control on account of easy structural collapse.Herein,a facile supramolecular electrostatic self-assembly strategy has been developed for the first time to fabricate mesoporous thin-walled g-C3N4 microtubes(mtw-CNT)with shell thickness of ca.13 nm.The morphological control of g-C3N4 enhances specific surface area by 12 times,induces stronger optical absorption,widens bandgap by 0.18 e V,improves photocurrent density by 2.5 times,and prolongs lifetimes of charge carriers from bulk to surface,compared with those of bulk g-C3N4.As a consequence,the transformed g-C3N4 exhibits the optimum photocatalytic H2-production rate of 3.99 mmol·h^-1·g^-1(λ>420 nm)with remarkable apparent quantum efficiency of 8.7%(λ=420±15 nm)and long-term stability.Moreover,mtw-CNT also achieves high photocatalytic CO2-to-CO selectivity of 96%(λ>420 nm),much better than those on the most previously reported porous g-C3N4 photocatalysts prepared by the conventional hard-templating and soft-templating methods.展开更多
The deviation of flow characteristics from the predictions of the conventional theory for microtubes was attrib- uted to the change of fluid viscosity resulted from the interactions between the molecules on solid wall...The deviation of flow characteristics from the predictions of the conventional theory for microtubes was attrib- uted to the change of fluid viscosity resulted from the interactions between the molecules on solid wall and in fluid. The degree of this departure is dependent on the microtubes materials. A concept of equivalent thickness with which conventional theory can be used to predict the flow in microtubes without modifying the fluid viscosity was put forward. The values of equivalent thickness for fused silica and stainless steel materials were determined as 1.8 μm and 1.5 μm, respectively, by repeated numeri- cal simulation.展开更多
The potato minitubers have been widely used for the elite seed propagation to improve the seed potato system in China. However, little information is available for an efficient production of the minitubers with high p...The potato minitubers have been widely used for the elite seed propagation to improve the seed potato system in China. However, little information is available for an efficient production of the minitubers with high plant density in the protected growing conditions like plastic houses. In present research, the minitubers of a wide-grown potato variety, Favorita, were produced with the microtubers from tissue culture and the tip-cuttings of the microtuber plants. Three plant densities, 200, 400 and 600 microtubers or plants m-2 were set up with the randomized block design of 3 replications and the experiment was repeated in 4 seasons in 2009-2010. The canopy development, light interception, dry weight production and partitioning, tuberization and tuber weight were investigated to elucidate the mechanism by which the plant density affects the formation and growth of the minitubers. The results showed that the number of the tubers formed per unite area was in line with the increase in plant density. The difference in leaf area index （LAI） between the plant densities, especially in early stage of the plant growth, resulted in more radiation interception and dry weight producing in higher plant density than in lower one. However, our analysis demonstrated that the conversion coefficient of the cumulative intercepted radiation to plant weight and the dry weight partition rate to the tubers were constant between plant densities, suggesting that less amount of the photoassimilates partitioned to individual tubers is causal for more small tubers in high plant density. A negative exponential curve model, determined by total number of tubers produced per unit area and the mean tuber weight, fitted well to the tuber size distribution pattern. The optimum plant density could be estimated from this model for a maximum production of the minitubers with desired size.展开更多
To fully exploit the superiority of tubular structures,in this study,we systematically explore the optimal preparation conditions for Ni/Co_(3)O_(4),including cation species and content,additive species and content,an...To fully exploit the superiority of tubular structures,in this study,we systematically explore the optimal preparation conditions for Ni/Co_(3)O_(4),including cation species and content,additive species and content,and anion species.Our results reveal that the formation of an initial cobalt nickel acetate hydroxide prism is the key factor and directly affects the final microtubular structure.Moreover,P is subsequently doped into the Ni/Co_(3)O_(4)lattice to increase the M^(3+)/M^(2+)molar ratio(M=Co and Ni),promote reaction kinetics,and optimize electronic structure.Consequently,the oxygen evolution reaction performance of P-doped tubular Ni/Co_(3)O_(4)is significantly higher than that of undoped Ni/Co_(3)O_(4)and the state-of-the-art RuO_(2)electrocatalyst.展开更多
Doping of foreign atoms and construction of unique structures are considered as effective approaches to design high-activity and strongdurability electrocatalysts.Herein,we report Fe-doped nickel hydroxide carbonate h...Doping of foreign atoms and construction of unique structures are considered as effective approaches to design high-activity and strongdurability electrocatalysts.Herein,we report Fe-doped nickel hydroxide carbonate hierarchical microtubes with Ag nanoparticles(denoted Ag/NiFeHC HMTs)through hydrolysis precipitation process.Experimental tests and density functional theory calculations reveal that Fe doping can tune the electron configuration to enhance the conductivity,markedly improve the electrochemical surface area to expose more active sites,and act as reactive centers to lower the free energy of the rate determination step.In addition,the unique hierarchical structure can also offer active sites and excellent cycling stability.Benefitting from these advantages,the as-obtained Ag/NiFeHC HMTs show excellent oxygen evolution reaction activity,with an overpotential of 208 mV at 10 mA cm^(−2)in 1.0M KOH.Also,it could achieve long-term stability at a current density of 20 mA cm^(−2)for 24 h.展开更多
Magnesium(Mg)alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability.However,in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer...Magnesium(Mg)alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability.However,in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer from a rapid corrosion rate and severe localized corrosion,which is limiting their widespread application.To solve the problem of uneven degradation of stents,a HTHE(long-time and high-temperature heat treatment,large-reduction-ratio hot extrusion)process is used to manufacture Mg-Zn-Y-Nd alloy microtubes in this study.The heat treatment is to dissolve alloying elements and reduce the size of SPPs,and the hot extrusion is to acquire fine-grained and strongly textured microtubes.The microstructural characterization shows that coarse second phases in as-cast alloy are refined and uniformly distributed in matrix of microtubes.After hot extrusion,microtubes show strong texture with basal plain oriented parallel to the longitudinal section(LS).The corrosion testing indicates that severe localized corrosion occurs on the cross section(CS)while localized corrosion is alleviated on the LS.Based on the different corrosion properties of the LS and CS,HTHEed microtubes are promising for solving the problems of rapid corrosion rate and severe localized corrosion of Mg alloy stents.展开更多
It is obvious that the pressure gradient along the axial direction in a pipe flow keeps constant according to the Hagen-Poiseuille equation. However, recent experiments indicated that the distribution of the pressure ...It is obvious that the pressure gradient along the axial direction in a pipe flow keeps constant according to the Hagen-Poiseuille equation. However, recent experiments indicated that the distribution of the pressure seemed no longer linear for liquid flows in microtubes driven by high pressure （1-30MPa）. Based on H-P equation with slip boundary condition and Bridgman＇s relation of viscosity vs. static pressure, the nonlinear distribution of pressure along the axial direction is analyzed in this paper. The revised standard Poiseuille number with the effect of pressure-dependent viscosity taken into account agrees well with the experimental results. Therefore, the dependence of the viscosity on the pressure is one of the dominating factors under high driven pressure, and is represented by an important property coefficient α of the liquid.展开更多
The microtuber is considered one of the most effective means of spreading basic materials, as well as transporting and preserving potato germplasm varieties. To define the optimal conditions for the potato microtuber ...The microtuber is considered one of the most effective means of spreading basic materials, as well as transporting and preserving potato germplasm varieties. To define the optimal conditions for the potato microtuber in vitro germination of Aida, Atlas and Odessa varieties, the effects of temperature, physiological age and grade (size) were evaluated. The study conducted at three different temperature levels has demonstrated that the most favorable temperature for microtuber germination at a higher and faster germination rate was 25℃, regardless of the variety. In addition, microtubers of large caliber, greater than 4 mm, germinate more quickly, with a higher germination rate, than smaller size ones (less than 4 mm) for all genotypes. For Atlas, Aida and Odessa varieties, a germination rate equal to 86.66%, 70% and 70% respectively, was obtained for microtubers with a caliber superior to 4 mm. Physiological age influences microtuber germination. The mean length of sprouts, reached after a 7 week incubation period, was more marked at “multiple sprout” and “branched sprout” stages than at a “monosprout” stage. The average length was 2.35 cm, 2.48 cm and 1.5 cm, respectively. Thus, it is necessary to plant microtubers at a “multiple sprout” stage to optimize their yield in plants and minitubers.展开更多
The fabrication of superhydrophobic surfaces and the studies on water flow characteristics therein are of great significance to many industrial areas as well as to science and technology development. Experiments were ...The fabrication of superhydrophobic surfaces and the studies on water flow characteristics therein are of great significance to many industrial areas as well as to science and technology development. Experiments were car- ried out to investigate slip characteristics of water flowing in circular superhydrophobic microtubes within lam- inar flow region. The superhydrophobic microtubes of stainless steel were fabricated with chemical etching- fluorination treatment. An experimental setup was designed to measure the pressure drop as function of water flow rate. For comparison, superhydrophilic tubes were also tested. Poiseuille number Po was found to be smaller for the superhydrophobic microtubes than that for superhydrophilic ones. The pressure drop reduc- tion ranges from 8% to 31%. It decreases with increasing Reynolds number when Re 〈 900, owing to the transition from Cassie state to Wenze] state. However, it is almost unchanged with further increasing Re after Re 〉 900. The slip length in superhydrophobic microtubes also exhibits a Reynolds number dependence similarly to the pressure drop reduction. The relation between slip length and Darcy friction factor is theoretically analyzed with consideration of surface roughness effect, which was testified with the experimental results.展开更多
Compared with noble metals, improving the sensitivity of semiconducting surface-enhanced Raman scattering(SERS) substrates is of great significance to their fundamental research and practical application of Raman spec...Compared with noble metals, improving the sensitivity of semiconducting surface-enhanced Raman scattering(SERS) substrates is of great significance to their fundamental research and practical application of Raman spectroscopy. Herein, a simple chemical method is developed to synthesize a rhenium trioxide(ReO_(3)) microtubes assembled with highly crystalline nanoparticles. The ReO_(3) microtubes show a strong and well-defined surface plasmon resonance(SPR) behavior in visible region, which is rare for non-noble metals. As a low-cost SERS substrate, the plasmonic ReO_(3) microtubes exhibit a Raman enhancement factor of 8.9×10^(5) and a lowest detection limit of 1.0×10^(-9) mol/L for phenolic pollutants. Moreover, these ReO_(3) microtubule SERS substrates show excellent chemical stability and can resist the corrosion of strong acids and bases.展开更多
Non-enzymatic electrochemical sensors for the determination of hydrogen peroxide(H_(2)O_(2))have attracted more and more concerns.A series of nickel and cobalt double oxides(Ni_(x)Co_(y)-DO)with the different ratios o...Non-enzymatic electrochemical sensors for the determination of hydrogen peroxide(H_(2)O_(2))have attracted more and more concerns.A series of nickel and cobalt double oxides(Ni_(x)Co_(y)-DO)with the different ratios of Ni/Co have been prepared by a polyol-mediated solvothermal method for H_(2)O_(2)detection.The obtained products exhibit honeycomb-like open porous microtubes constituted with the low-dimensional nanostructured Ni_(x)Co_(y)-DO blocks after the calcination treatment.Compared with nickel oxides,the introduced Co ions in Ni_(x)Co_(y)-DO can induce the production of surficial oxygen vacancies,and further enhance the electrode surface activity.In particular,the NiCo-DO sample(with an atomic ratio of Ni/Co=4:3)shows the richest surficial oxygen vacancies and presents the highest H_(2)O_(2)detection activity among all the as-prepared samples,demonstrating an excellent sensitivity of698.60μAL mmol^(-1)cm^(-2)(0~0.4 mmol/L),low detection limit(0.28μmol/L,S/N=3),as well as long stability,high selectivity and good reproducibility.This work lends a new impetus to the potential application of double metal oxides for the next generation of non-enzymatic sensors.展开更多
The residual effects of sucrose concentrations (80 or 100 g·L-1) and hormonal treatments (BAP + Kinetin or Coumarin) of tuberization medium on in vitro microtubers germination of three potato varieties (Solanum t...The residual effects of sucrose concentrations (80 or 100 g·L-1) and hormonal treatments (BAP + Kinetin or Coumarin) of tuberization medium on in vitro microtubers germination of three potato varieties (Solanum tuberosum L.) so called Aida, Atlas and Odessa, are described. After 3 weeks of incubation at 28℃ ± 1℃, 70% of Aida microtubers variety, previously formed in the MT2 medium [MS/2 + 80 g·L-1 Sucrose], germinated. The best germination rate for varieties Atlas (100%) and Odessa (66.66%) was obtained on microtubers previously formed in the medium MT2 [MS/2 + 100 g·L-1 Sucrose]. The addition of hormones in the tuberization medium allowed optimizing the microtubers germination of the Aida variety unlike the other varieties. Indeed, for the Aida variety, the combination M5 [Kin 2.5 mg·L-1 + Coum 0.025 mg·L-1 + Sucrose 80 g·L-1] increased the germination rate from 70% up to 93.33%. The best germination rate (90%), noticed with microtubers of Atlas variety, initially formed in M2 medium [Kin 1 mg·L-1 + BAP 1 mg·L-1 + Sucrose 100 g·L-1], was lower than that one (100%) obtained on medium without hormones. For Odessa variety, the maximum germination rate (53.33%) of microtubers, from the medium M4 [Kin 2.5 mg·L-1 + BAP 1 mg·L-1 + Sucrose 100 g·L-1], was also lower than that one (66.66%) observed in the medium without hormones. Aida and Atlas varieties thus offer a better germination rate than Odessa after their cold storage.展开更多
[ Objective] This study aimed to investigate the variation rule of total RNA concentration during formation of microtubers of PineUia ternata induced by sucrose. [ Method ] Plantlets of P. ternata were used as experim...[ Objective] This study aimed to investigate the variation rule of total RNA concentration during formation of microtubers of PineUia ternata induced by sucrose. [ Method ] Plantlets of P. ternata were used as experimental materials. Total RNA concentration was determined with spectrophotometer, and the variation of total RNA was analyzed before and after formation of P. ternata microtubers treated with different concentrations of sucrose using DDRT-PCR technology. [ Result] Total RNA concentration of P. ternata treated with different concentrations of sucrose varied greatly, which showed an upward trend in the first 15 d, de- clined from 15~ d to 25th d, and slightly raised from 25＇h d to 30＇8 d. Microtubers formed under various sucrose treatments showed an increase in RNA concentration after induction, and it was assumed that the treatment of high concentrations of sucrose might have activated the expression of development-related＇ genes in P. ter- nata microtubers. [ Conclusion] This study provides the basis for revealing the related gene expression information and molecular mechanism during formation of P. ternata microtubers induced by sucrose.展开更多
It is the simplest,fastest and effective way to improve the yield level of potato by selecting high quality virus-free seed potato for field production and maintaining the original characters of virus-free minituber. ...It is the simplest,fastest and effective way to improve the yield level of potato by selecting high quality virus-free seed potato for field production and maintaining the original characters of virus-free minituber. Microtuber is featured by small volume,no pathogen,convenient storage and transportation,which can be induced in summer with high temperature and humidity,and overcome a series of problems such as poor survival rate of transplanted test-tube plantlets,and easy pollution of cutting tips. Therefore,it can replace conventional test-tube plantlets directly for reproduction. Meantime,if minitubers are sown ahead of time using cold frame,the growth stage of potato minituber will avoid the occurrence period of aphids. The use of gauze cover for insect prevention has good effect on maintaining the excellent characters of microtuber. The yield and quality of virus-free potato are greatly improved by means of virus-free culture of shoot tip seedlings,subculture propagation of virus-free seedlings,induction of microtubers by dark culture,cultivation of breeder’s seeds in greenhouse and screenhouse to preserve the characters of potato.展开更多
The potato (</span><i><span style="font-family:Verdana;">Solanum tuberosum</span></i><span style="font-family:Verdana;"> L.) is a vegetable that ranks fifth in t...The potato (</span><i><span style="font-family:Verdana;">Solanum tuberosum</span></i><span style="font-family:Verdana;"> L.) is a vegetable that ranks fifth in the world for human consumption. Its importance is growing more and more in the Senegalese diet. However, the potato production in Senegal does not meet the needs of the market, which maintains dependence on the outside for the supply of quality seeds. In addition, these imported seeds do not often have phytosanitary qualities required for local production in the Sahelian zone. The </span><i><span style="font-family:Verdana;">in vitro </span></i><span style="font-family:Verdana;">production of microtubers, used as seed, has been shown to be one of the mos</span><span style="font-family:Verdana;">t efficient means for propagation of basic material. To overcome the constraints linked to the supply and availability of potato seeds, with high germination capacity, the impact of the microtuber size on the yield of the plants under semi-controlled conditions was examined. The pre-germinated</span><span style="font-family:Verdana;"> microtubers were produced </span><i><span style="font-family:Verdana;">in vitro </span></i><span style="font-family:Verdana;">from vitroplants of 3 different varieties (</span><i><span style="font-family:Verdana;">Aida</span></i><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Atlas</span></i><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Odessa</span></i><span style="font-family:Verdana;">) adapted to the edaphic-climatic conditions of Senegal. The effects of the seed sizes of microtubers, greater than 4 mm, sown under semi-controlled conditions, on the yield of the plants</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> result in an increase in the ratio, in the vegetative development of the plants, but also in the number and size of the minitubers harvested. The yield of the plants also depends on the variety. It can therefore be envisaged to produce local potato seeds from microtubers and minitubers.展开更多
基金supported by the National Natural Science Foundation of China(No.12174199)the Wanjing Horizontal Research and Development Fund for Nature(No.HJ1060319960015).
文摘Based on optofluidics and whispering gallery mode(WGM)theory,here an optofluidic refractive index sensor with microtube-coupled suspended core fiber(SCF)is proposed.It solves the issues of general sensors with microcavity-coupled fiber taper such as too fragile,unstable performance due to open coupling,poor portability and repeatability,while overcoming the poor performance of low refractive index sensing in general full-package fiber sensors.The sensor only needs a very small amount of liquid sample(about 1.8 nL).The proposed sensor combines the excellent performance of full package,optofluidics and WGM resonator.The resonant characteristics and sensing performance of the sensor are analyzed and discussed by the theoretical simulation.The simulation results indicate that the sensor has a wide refractive index sensing range(1.330-1.700)and good performance.The resonance wavelength shift has a good linear relationship with the liquid refractive index variation.In the low refractive index region,the sensitivity is 222.5-247.5 nm/RIU,Q-factor is 1.03×10^(3) and the detection limit is 3.64×10^(-4) RIU.In the medium and high refractive index regions,the sensitivity is 564.4-846.2 nm/RIU,Q-factor is up to 8.62×10^(4),and the detection limit can be as low as 1.29×10^(-6) RIU.The sensor exhibits a high sensitivity,a high Q-factor and a very low detection limit.
基金the financial support of the National Key Research and Development Program of China(2018YFC1106703)the Key Projects of the Joint Fund of the National Natural Science Foundation of China(U1804251)。
文摘The degradation of Mg alloys relates to the service performance of Mg alloy biodegradable implants.In order to investigate the degradation behavior of Mg alloys as vascular stent materials in the near service environment,the hot-extruded fine-grained Mg-Zn-Y-Nd alloy microtubes,which are employed to manufacture vascular stents,were tested under radial compressive stress in the dynamic Hanks'Balanced Salt Solution(HBSS).The results revealed that the high flow rate accelerates the degradation of Mg alloy microtubes and its degradation is sensitive to radial compressive stress.These results contribute to understanding the service performance of Mg alloys as vascular stent materials.
基金Project supported by the National Natural Science Foundation of China （Grant No 10474078） and the Science Foundation of the Education 0ffice of Shanxi Province, China.
文摘This paper reports that pure hexagonal aluminium nitride microtubes and nanowires growing along the [0001] direction have been successfully synthesized by directly reacting AlCl3 with NaN3 at low temperature （450℃） under condition of non-solvent system. The grey-white powder of reacting product was characterized by high-resolution transmission electron microscope （HRTEM）, which shows that the powder is long straight-wire morphology with outer diameter from 40nm to 300 nm and length up to several micrometres. The results of both electron diffraction （ED） and x-ray diffraction （XRD） indicate that the AlN microtubes have a pure hexagonal monocrystal tubular structure with the combination of the curled AlN nanobelts. Room-temperature photoluminescence spectrum of the synthesized sample showed an emission peak, which is closely related to the small size of the microtubes.
基金supported by the National Natural Science Foundation of China(No.50821062)the National 973 Project(No.2005CCA00800).
文摘A newly natural fine template, kapok fiber, for microtube preparation was reported. Large scale microtubes with high length/diameter ratio and controllable wall thickness and morphology have been successfully fabricated with this template. It is a wildly available, low-cost, environmental friendly and fine structured natural template for microtubes. Its thin wall thickness is only about 1-2 um that means the whole template material is tiny and easy for removing. Even there is any residue the amount can be ignored. When the template is covered with a shell component, hollow structured microtube could be obtained by removing the thin inner template, and its shape could be the same as that of the original template （positive copy of the template＇s shape）. The products have high length/diameter ratio and uniform tubular structure. By further modifying the fabricating methods, facile fabrication not only exists for polypyrrole （PPy） in electrochemical deposition, but also for many other organic and inorganic materials. The surface morphology and wall thickness of the resultant microtubes can be easily modulated by controlling the processing conditions. This natural fiber is predicted to be a fine template for fabricating large scale microtubes with large cavity and high length/diameter ratio.
文摘With the detoxicated seedling of a potato cultivation breed named “Mire” as the material, the effect of auxins CCC, 6-BA, and active carbon to microtubers of potato (Solanum tubersum L.) was investigated under the in-vitro circumstances. The result indicated the exogenous auxins improved the production and quality of microtubers of potatoes. The effect of induction can be described as CCC > CCC + 6-BA > 6-BA > CK, the number of microtubers in per flask is 8.17 > 7.67 > 7.29 > 5.46, and the number of large potatoes in per flask is 6.33 > 5.17 > 3.17 > 1. In addition, by adding 0.5‰ of active charcoal, the growth period was shortened from 25.0 days to 9.33 days on average, and the amount of larger potatoes increased 8.54%. These results benefited the growth of microtubers of potato.
基金financially supported by the National Natural Science Foundation of China(21902051)the Natural Science Foundation of Fujian Province(2017J01014 and 2019J05090)the Graphene Power and Composite Research Center of Fujian Province(2017H2001)。
文摘For efficient solar energy conversion,the morphology engineering of hollow graphitic carbon nitride(gC3 N4)is one of the promising approachs benefiting from abundant exposed active sites and short photocarrier transport distances,but is difficult to control on account of easy structural collapse.Herein,a facile supramolecular electrostatic self-assembly strategy has been developed for the first time to fabricate mesoporous thin-walled g-C3N4 microtubes(mtw-CNT)with shell thickness of ca.13 nm.The morphological control of g-C3N4 enhances specific surface area by 12 times,induces stronger optical absorption,widens bandgap by 0.18 e V,improves photocurrent density by 2.5 times,and prolongs lifetimes of charge carriers from bulk to surface,compared with those of bulk g-C3N4.As a consequence,the transformed g-C3N4 exhibits the optimum photocatalytic H2-production rate of 3.99 mmol·h^-1·g^-1(λ>420 nm)with remarkable apparent quantum efficiency of 8.7%(λ=420±15 nm)and long-term stability.Moreover,mtw-CNT also achieves high photocatalytic CO2-to-CO selectivity of 96%(λ>420 nm),much better than those on the most previously reported porous g-C3N4 photocatalysts prepared by the conventional hard-templating and soft-templating methods.
基金Project (No. 20299030) supported by the National Natural ScienceFoundation of China
文摘The deviation of flow characteristics from the predictions of the conventional theory for microtubes was attrib- uted to the change of fluid viscosity resulted from the interactions between the molecules on solid wall and in fluid. The degree of this departure is dependent on the microtubes materials. A concept of equivalent thickness with which conventional theory can be used to predict the flow in microtubes without modifying the fluid viscosity was put forward. The values of equivalent thickness for fused silica and stainless steel materials were determined as 1.8 μm and 1.5 μm, respectively, by repeated numeri- cal simulation.
基金supported by Earmarked Fund for Morden Agro-industry Technology Research System(CARS-10-P08)
文摘The potato minitubers have been widely used for the elite seed propagation to improve the seed potato system in China. However, little information is available for an efficient production of the minitubers with high plant density in the protected growing conditions like plastic houses. In present research, the minitubers of a wide-grown potato variety, Favorita, were produced with the microtubers from tissue culture and the tip-cuttings of the microtuber plants. Three plant densities, 200, 400 and 600 microtubers or plants m-2 were set up with the randomized block design of 3 replications and the experiment was repeated in 4 seasons in 2009-2010. The canopy development, light interception, dry weight production and partitioning, tuberization and tuber weight were investigated to elucidate the mechanism by which the plant density affects the formation and growth of the minitubers. The results showed that the number of the tubers formed per unite area was in line with the increase in plant density. The difference in leaf area index （LAI） between the plant densities, especially in early stage of the plant growth, resulted in more radiation interception and dry weight producing in higher plant density than in lower one. However, our analysis demonstrated that the conversion coefficient of the cumulative intercepted radiation to plant weight and the dry weight partition rate to the tubers were constant between plant densities, suggesting that less amount of the photoassimilates partitioned to individual tubers is causal for more small tubers in high plant density. A negative exponential curve model, determined by total number of tubers produced per unit area and the mean tuber weight, fitted well to the tuber size distribution pattern. The optimum plant density could be estimated from this model for a maximum production of the minitubers with desired size.
文摘To fully exploit the superiority of tubular structures,in this study,we systematically explore the optimal preparation conditions for Ni/Co_(3)O_(4),including cation species and content,additive species and content,and anion species.Our results reveal that the formation of an initial cobalt nickel acetate hydroxide prism is the key factor and directly affects the final microtubular structure.Moreover,P is subsequently doped into the Ni/Co_(3)O_(4)lattice to increase the M^(3+)/M^(2+)molar ratio(M=Co and Ni),promote reaction kinetics,and optimize electronic structure.Consequently,the oxygen evolution reaction performance of P-doped tubular Ni/Co_(3)O_(4)is significantly higher than that of undoped Ni/Co_(3)O_(4)and the state-of-the-art RuO_(2)electrocatalyst.
基金Zhejiang Provincial Natural Science Foundation of China,Grant/Award Number:LQ20B010002。
文摘Doping of foreign atoms and construction of unique structures are considered as effective approaches to design high-activity and strongdurability electrocatalysts.Herein,we report Fe-doped nickel hydroxide carbonate hierarchical microtubes with Ag nanoparticles(denoted Ag/NiFeHC HMTs)through hydrolysis precipitation process.Experimental tests and density functional theory calculations reveal that Fe doping can tune the electron configuration to enhance the conductivity,markedly improve the electrochemical surface area to expose more active sites,and act as reactive centers to lower the free energy of the rate determination step.In addition,the unique hierarchical structure can also offer active sites and excellent cycling stability.Benefitting from these advantages,the as-obtained Ag/NiFeHC HMTs show excellent oxygen evolution reaction activity,with an overpotential of 208 mV at 10 mA cm^(−2)in 1.0M KOH.Also,it could achieve long-term stability at a current density of 20 mA cm^(−2)for 24 h.
基金financial support of Key Projects of the Joint Fund of the National Natural Science Foundation of China(Grant No:U1804251)the National Key Research and Development Program of China(2016YFC1102403,2018YFC1106703 and 2017YFB0702504)+1 种基金China Scholarship Council for the award of fellowship and funding(No.201707040058)China Scholarship Council for the award of fellowship and funding(No.201607040051)。
文摘Magnesium(Mg)alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability.However,in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer from a rapid corrosion rate and severe localized corrosion,which is limiting their widespread application.To solve the problem of uneven degradation of stents,a HTHE(long-time and high-temperature heat treatment,large-reduction-ratio hot extrusion)process is used to manufacture Mg-Zn-Y-Nd alloy microtubes in this study.The heat treatment is to dissolve alloying elements and reduce the size of SPPs,and the hot extrusion is to acquire fine-grained and strongly textured microtubes.The microstructural characterization shows that coarse second phases in as-cast alloy are refined and uniformly distributed in matrix of microtubes.After hot extrusion,microtubes show strong texture with basal plain oriented parallel to the longitudinal section(LS).The corrosion testing indicates that severe localized corrosion occurs on the cross section(CS)while localized corrosion is alleviated on the LS.Based on the different corrosion properties of the LS and CS,HTHEed microtubes are promising for solving the problems of rapid corrosion rate and severe localized corrosion of Mg alloy stents.
基金The project supported by the Chinese Academy of Sciences Major Innovation Project (KJCX2-SW-L2)the National Natural Science Foundation of China (10272107)The English text was polished by Yunming Chen
文摘It is obvious that the pressure gradient along the axial direction in a pipe flow keeps constant according to the Hagen-Poiseuille equation. However, recent experiments indicated that the distribution of the pressure seemed no longer linear for liquid flows in microtubes driven by high pressure （1-30MPa）. Based on H-P equation with slip boundary condition and Bridgman＇s relation of viscosity vs. static pressure, the nonlinear distribution of pressure along the axial direction is analyzed in this paper. The revised standard Poiseuille number with the effect of pressure-dependent viscosity taken into account agrees well with the experimental results. Therefore, the dependence of the viscosity on the pressure is one of the dominating factors under high driven pressure, and is represented by an important property coefficient α of the liquid.
文摘The microtuber is considered one of the most effective means of spreading basic materials, as well as transporting and preserving potato germplasm varieties. To define the optimal conditions for the potato microtuber in vitro germination of Aida, Atlas and Odessa varieties, the effects of temperature, physiological age and grade (size) were evaluated. The study conducted at three different temperature levels has demonstrated that the most favorable temperature for microtuber germination at a higher and faster germination rate was 25℃, regardless of the variety. In addition, microtubers of large caliber, greater than 4 mm, germinate more quickly, with a higher germination rate, than smaller size ones (less than 4 mm) for all genotypes. For Atlas, Aida and Odessa varieties, a germination rate equal to 86.66%, 70% and 70% respectively, was obtained for microtubers with a caliber superior to 4 mm. Physiological age influences microtuber germination. The mean length of sprouts, reached after a 7 week incubation period, was more marked at “multiple sprout” and “branched sprout” stages than at a “monosprout” stage. The average length was 2.35 cm, 2.48 cm and 1.5 cm, respectively. Thus, it is necessary to plant microtubers at a “multiple sprout” stage to optimize their yield in plants and minitubers.
基金the National Natural Science Foundation of China(20476014,51376030)
文摘The fabrication of superhydrophobic surfaces and the studies on water flow characteristics therein are of great significance to many industrial areas as well as to science and technology development. Experiments were car- ried out to investigate slip characteristics of water flowing in circular superhydrophobic microtubes within lam- inar flow region. The superhydrophobic microtubes of stainless steel were fabricated with chemical etching- fluorination treatment. An experimental setup was designed to measure the pressure drop as function of water flow rate. For comparison, superhydrophilic tubes were also tested. Poiseuille number Po was found to be smaller for the superhydrophobic microtubes than that for superhydrophilic ones. The pressure drop reduc- tion ranges from 8% to 31%. It decreases with increasing Reynolds number when Re 〈 900, owing to the transition from Cassie state to Wenze] state. However, it is almost unchanged with further increasing Re after Re 〉 900. The slip length in superhydrophobic microtubes also exhibits a Reynolds number dependence similarly to the pressure drop reduction. The relation between slip length and Darcy friction factor is theoretically analyzed with consideration of surface roughness effect, which was testified with the experimental results.
基金financial support from the National Natural Science Foundation of China(No.51771175)the Science Foundation of State Administration of market supervision(No.2021MK164)。
文摘Compared with noble metals, improving the sensitivity of semiconducting surface-enhanced Raman scattering(SERS) substrates is of great significance to their fundamental research and practical application of Raman spectroscopy. Herein, a simple chemical method is developed to synthesize a rhenium trioxide(ReO_(3)) microtubes assembled with highly crystalline nanoparticles. The ReO_(3) microtubes show a strong and well-defined surface plasmon resonance(SPR) behavior in visible region, which is rare for non-noble metals. As a low-cost SERS substrate, the plasmonic ReO_(3) microtubes exhibit a Raman enhancement factor of 8.9×10^(5) and a lowest detection limit of 1.0×10^(-9) mol/L for phenolic pollutants. Moreover, these ReO_(3) microtubule SERS substrates show excellent chemical stability and can resist the corrosion of strong acids and bases.
基金supported by the National Natural Science Foundation of China(Nos.51432003,51802011 and 51125007)the Start-Up Fund for Talent Introduction of Beijing University of Chemical Technology(No.buctrc201806)the Fundamental Research Funds for the Central Universities(No.JD2010)。
文摘Non-enzymatic electrochemical sensors for the determination of hydrogen peroxide(H_(2)O_(2))have attracted more and more concerns.A series of nickel and cobalt double oxides(Ni_(x)Co_(y)-DO)with the different ratios of Ni/Co have been prepared by a polyol-mediated solvothermal method for H_(2)O_(2)detection.The obtained products exhibit honeycomb-like open porous microtubes constituted with the low-dimensional nanostructured Ni_(x)Co_(y)-DO blocks after the calcination treatment.Compared with nickel oxides,the introduced Co ions in Ni_(x)Co_(y)-DO can induce the production of surficial oxygen vacancies,and further enhance the electrode surface activity.In particular,the NiCo-DO sample(with an atomic ratio of Ni/Co=4:3)shows the richest surficial oxygen vacancies and presents the highest H_(2)O_(2)detection activity among all the as-prepared samples,demonstrating an excellent sensitivity of698.60μAL mmol^(-1)cm^(-2)(0~0.4 mmol/L),low detection limit(0.28μmol/L,S/N=3),as well as long stability,high selectivity and good reproducibility.This work lends a new impetus to the potential application of double metal oxides for the next generation of non-enzymatic sensors.
文摘The residual effects of sucrose concentrations (80 or 100 g·L-1) and hormonal treatments (BAP + Kinetin or Coumarin) of tuberization medium on in vitro microtubers germination of three potato varieties (Solanum tuberosum L.) so called Aida, Atlas and Odessa, are described. After 3 weeks of incubation at 28℃ ± 1℃, 70% of Aida microtubers variety, previously formed in the MT2 medium [MS/2 + 80 g·L-1 Sucrose], germinated. The best germination rate for varieties Atlas (100%) and Odessa (66.66%) was obtained on microtubers previously formed in the medium MT2 [MS/2 + 100 g·L-1 Sucrose]. The addition of hormones in the tuberization medium allowed optimizing the microtubers germination of the Aida variety unlike the other varieties. Indeed, for the Aida variety, the combination M5 [Kin 2.5 mg·L-1 + Coum 0.025 mg·L-1 + Sucrose 80 g·L-1] increased the germination rate from 70% up to 93.33%. The best germination rate (90%), noticed with microtubers of Atlas variety, initially formed in M2 medium [Kin 1 mg·L-1 + BAP 1 mg·L-1 + Sucrose 100 g·L-1], was lower than that one (100%) obtained on medium without hormones. For Odessa variety, the maximum germination rate (53.33%) of microtubers, from the medium M4 [Kin 2.5 mg·L-1 + BAP 1 mg·L-1 + Sucrose 100 g·L-1], was also lower than that one (66.66%) observed in the medium without hormones. Aida and Atlas varieties thus offer a better germination rate than Odessa after their cold storage.
基金Supported by National Natural Science Foundation of China (30973963)Anhui Provincial Natural Science Foundation (090413252)Key Program of Natural Science Research of Anhui Provincial Universities (KJ2009A160)
文摘[ Objective] This study aimed to investigate the variation rule of total RNA concentration during formation of microtubers of PineUia ternata induced by sucrose. [ Method ] Plantlets of P. ternata were used as experimental materials. Total RNA concentration was determined with spectrophotometer, and the variation of total RNA was analyzed before and after formation of P. ternata microtubers treated with different concentrations of sucrose using DDRT-PCR technology. [ Result] Total RNA concentration of P. ternata treated with different concentrations of sucrose varied greatly, which showed an upward trend in the first 15 d, de- clined from 15~ d to 25th d, and slightly raised from 25＇h d to 30＇8 d. Microtubers formed under various sucrose treatments showed an increase in RNA concentration after induction, and it was assumed that the treatment of high concentrations of sucrose might have activated the expression of development-related＇ genes in P. ter- nata microtubers. [ Conclusion] This study provides the basis for revealing the related gene expression information and molecular mechanism during formation of P. ternata microtubers induced by sucrose.
基金Supported by Special Project of Potato Industry Research System in Shandong Province (SDAIT-14)。
文摘It is the simplest,fastest and effective way to improve the yield level of potato by selecting high quality virus-free seed potato for field production and maintaining the original characters of virus-free minituber. Microtuber is featured by small volume,no pathogen,convenient storage and transportation,which can be induced in summer with high temperature and humidity,and overcome a series of problems such as poor survival rate of transplanted test-tube plantlets,and easy pollution of cutting tips. Therefore,it can replace conventional test-tube plantlets directly for reproduction. Meantime,if minitubers are sown ahead of time using cold frame,the growth stage of potato minituber will avoid the occurrence period of aphids. The use of gauze cover for insect prevention has good effect on maintaining the excellent characters of microtuber. The yield and quality of virus-free potato are greatly improved by means of virus-free culture of shoot tip seedlings,subculture propagation of virus-free seedlings,induction of microtubers by dark culture,cultivation of breeder’s seeds in greenhouse and screenhouse to preserve the characters of potato.
文摘The potato (</span><i><span style="font-family:Verdana;">Solanum tuberosum</span></i><span style="font-family:Verdana;"> L.) is a vegetable that ranks fifth in the world for human consumption. Its importance is growing more and more in the Senegalese diet. However, the potato production in Senegal does not meet the needs of the market, which maintains dependence on the outside for the supply of quality seeds. In addition, these imported seeds do not often have phytosanitary qualities required for local production in the Sahelian zone. The </span><i><span style="font-family:Verdana;">in vitro </span></i><span style="font-family:Verdana;">production of microtubers, used as seed, has been shown to be one of the mos</span><span style="font-family:Verdana;">t efficient means for propagation of basic material. To overcome the constraints linked to the supply and availability of potato seeds, with high germination capacity, the impact of the microtuber size on the yield of the plants under semi-controlled conditions was examined. The pre-germinated</span><span style="font-family:Verdana;"> microtubers were produced </span><i><span style="font-family:Verdana;">in vitro </span></i><span style="font-family:Verdana;">from vitroplants of 3 different varieties (</span><i><span style="font-family:Verdana;">Aida</span></i><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Atlas</span></i><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;"> Odessa</span></i><span style="font-family:Verdana;">) adapted to the edaphic-climatic conditions of Senegal. The effects of the seed sizes of microtubers, greater than 4 mm, sown under semi-controlled conditions, on the yield of the plants</span></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> result in an increase in the ratio, in the vegetative development of the plants, but also in the number and size of the minitubers harvested. The yield of the plants also depends on the variety. It can therefore be envisaged to produce local potato seeds from microtubers and minitubers.
