Plant tissue culture systems have enormous potential in fundamental re- search and for commercial applications such as horticultural industry. The process of tissue culture is companied with a series of changes in res...Plant tissue culture systems have enormous potential in fundamental re- search and for commercial applications such as horticultural industry. The process of tissue culture is companied with a series of changes in respect to morphology, physiology, biochemistry, molecule and epigenetics. The changes at molecule levels mainly include genetic variation, DNA sequence variation, chromosomal variation and epigenetic regulation （DNA methylation, histone modification, chromatin remodeling, small RNA regulation）. These changes are believed to facilitate explant adaptation to culture conditions and to help subsequent morphogenesis processes. Nowadays, it has played a crucial part in commercial applications and in basic research into cell biology, genetics and biochemistry, etc. In present review, we shed light on the fun- damental of plant tissue culture, culture medium preparation, explant selection, mechanism of action of various hormones, the three major problems （explant pollu- tion, browning, plantlets vitrification） and the prevention measures in tissue culture, and elaborated on in vitro propagation of plants, virus-free seedling cultivation, cry- opreservation, artificial seeds and molecule levels changes during in vitro culture further.展开更多
Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient relea...Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release profiles of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate sodium could not improve water resistance performance and glass transition temperature Tgof coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and Tg. Incorporation of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated controlled release fertilizer, with the 30-day cumulative nutrient release reduced to 16% and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection.展开更多
Electrical resistance strain gauges(SGs) are useful tools for experimental stress analysis and the strain sensing elements in many electromechanical transducers including load cells,pressure transducers,torque meters,...Electrical resistance strain gauges(SGs) are useful tools for experimental stress analysis and the strain sensing elements in many electromechanical transducers including load cells,pressure transducers,torque meters,accelerometers,force cells,displacement transducers and so forth.The commonly used commercial crystalline strain sensing materials of SGs are in the form of wire or foil of which performance and reliability is not good enough due to their low electrical resistivity and incapacity to get thin thickness.Smaller SGs with single straight strand strain sensing materials,which are called ideal SG,are highly desirable for more than seven decades since the first SG was invented.Here,we show the development of a type of minuscule length scale strain gauge by using a bare and single straight strand metallic glassy fiber(MGF) with high resistivity,much smaller lengthscale,high elastic limits(2.16%) and especially the super piezoresistance effect.We anticipate that our metallic glassy fiber strain gauge(MGFSG),which moves toward the ideal SGs,would have wide applications for electromechanical transducers and stress analysis and catalyze development of more micro-and nanoscale metallic glass applications.展开更多
Ultrasonic vibration can be used for the micro-molding of metallic glasses(MGs)due to stress-softening and fast surface-diffusion effects.However,the structural rearrangement under ultrasonic vibration and its impact ...Ultrasonic vibration can be used for the micro-molding of metallic glasses(MGs)due to stress-softening and fast surface-diffusion effects.However,the structural rearrangement under ultrasonic vibration and its impact on the mechanical response of metallic glasses remain a puzzle.In this work,the plastic flow of the Zr35Ti30Cu8.25Be26.75 metallic glass with the applied ultrasonic-vibration energy of 140 J was investigated by nanoindentation.Both Kelvin and Maxwell-Voigt models have been adopted to analyze the structural evolution during the creep deformation.The increase of the characteristic relaxation time and the peak intensity of relaxation spectra can be found in the sample after ultrasonic vibration.It effectively improves the activation energy of atomic diffusion during the glass transition(Eg)and the growth of the crystal nucleus(Ep).A more homogenous plastic deformation with a weak loading-rate sensitivity of stress exponent is observed in the ultrasonic-vibrated sample,which coincides with the low pile-up and penetration depth as shown in the cross profile of indents.The structural rearrangement under resonance actuation demonstrated in this work might help us better understand the defect-activation mechanism for the plastic flow of amorphous systems.展开更多
In this paper, high-zirconium Zr66＋2xAl9-x（Ni1/3Cu2/3）25-x （x=0,1,2 at.%） bulk metallic glasses with high strength and large duc- tility were fabricated by copper mould casting. The effects of zirconium content o...In this paper, high-zirconium Zr66＋2xAl9-x（Ni1/3Cu2/3）25-x （x=0,1,2 at.%） bulk metallic glasses with high strength and large duc- tility were fabricated by copper mould casting. The effects of zirconium content on the glass-forming ability （GFA）, thermal properties and mechanical properties were investigated using X-ray diffractometer （XRD）, differential scanning calorimeter （DSC）, and mechanical testing system in compressive and three-point bending modes, respectively. The high-zirconium BMGs show the critical diameters of 3-5 ram, the supercooled liquid region ranging from 70 K to 99 K, and the yield strength of over 1700 MPa. The Zr70Al7（Ni1/3Cu2/3）23 BMG exhibits a large compressive plastic strain up to 21% and a high notch toughness value of 60.6 MPa m1/2. The increase in Zr content results in the decrease in GFA and thermostability, and in the improvement of plasticity under compressive and three-point bending conditions. The superior plasticity of high-zirconium BMGs is at- tributed to their high Poisson＇s ratio and small elastic modulus ratioμl/B.展开更多
基金Supported by Natural Science Foundation of Inner Mongolia(2012MS0516)~~
文摘Plant tissue culture systems have enormous potential in fundamental re- search and for commercial applications such as horticultural industry. The process of tissue culture is companied with a series of changes in respect to morphology, physiology, biochemistry, molecule and epigenetics. The changes at molecule levels mainly include genetic variation, DNA sequence variation, chromosomal variation and epigenetic regulation （DNA methylation, histone modification, chromatin remodeling, small RNA regulation）. These changes are believed to facilitate explant adaptation to culture conditions and to help subsequent morphogenesis processes. Nowadays, it has played a crucial part in commercial applications and in basic research into cell biology, genetics and biochemistry, etc. In present review, we shed light on the fun- damental of plant tissue culture, culture medium preparation, explant selection, mechanism of action of various hormones, the three major problems （explant pollu- tion, browning, plantlets vitrification） and the prevention measures in tissue culture, and elaborated on in vitro propagation of plants, virus-free seedling cultivation, cry- opreservation, artificial seeds and molecule levels changes during in vitro culture further.
基金Supported by the National 12th Five-Year Science and Technology Supporting Program(2011BAD11B01)the Research & Development Projects Cooperation Project of Chinese Academy of Sciences(YDJDBNJ-2012-023)
文摘Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release profiles of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate sodium could not improve water resistance performance and glass transition temperature Tgof coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and Tg. Incorporation of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated controlled release fertilizer, with the 30-day cumulative nutrient release reduced to 16% and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection.
基金support from the National Natural Science Foundation of China (Grant Nos. 50921091 and 50731008)the National Basic Research Program of China (973) (Grant Nos. 2007CB613904 and2010CB731603)
文摘Electrical resistance strain gauges(SGs) are useful tools for experimental stress analysis and the strain sensing elements in many electromechanical transducers including load cells,pressure transducers,torque meters,accelerometers,force cells,displacement transducers and so forth.The commonly used commercial crystalline strain sensing materials of SGs are in the form of wire or foil of which performance and reliability is not good enough due to their low electrical resistivity and incapacity to get thin thickness.Smaller SGs with single straight strand strain sensing materials,which are called ideal SG,are highly desirable for more than seven decades since the first SG was invented.Here,we show the development of a type of minuscule length scale strain gauge by using a bare and single straight strand metallic glassy fiber(MGF) with high resistivity,much smaller lengthscale,high elastic limits(2.16%) and especially the super piezoresistance effect.We anticipate that our metallic glassy fiber strain gauge(MGFSG),which moves toward the ideal SGs,would have wide applications for electromechanical transducers and stress analysis and catalyze development of more micro-and nanoscale metallic glass applications.
基金the National Natural Science Foundation of China(51631003,51871157 and 51601038)the Key Basic and Applied Research Program of Guangdong Province,China(2019B030302010)+3 种基金the Natural Science Foundation of Jiangsu Province,China(BK20171354)the Fundamental Research Funds for the Central Universities(2242020K40002)the Research and Practice Innovation Program for Postgraduates in Jiangsu Province(SJCX20_0038)Jiangsu Key Laboratory for Advanced Metallic Materials(BM2007204)。
文摘Ultrasonic vibration can be used for the micro-molding of metallic glasses(MGs)due to stress-softening and fast surface-diffusion effects.However,the structural rearrangement under ultrasonic vibration and its impact on the mechanical response of metallic glasses remain a puzzle.In this work,the plastic flow of the Zr35Ti30Cu8.25Be26.75 metallic glass with the applied ultrasonic-vibration energy of 140 J was investigated by nanoindentation.Both Kelvin and Maxwell-Voigt models have been adopted to analyze the structural evolution during the creep deformation.The increase of the characteristic relaxation time and the peak intensity of relaxation spectra can be found in the sample after ultrasonic vibration.It effectively improves the activation energy of atomic diffusion during the glass transition(Eg)and the growth of the crystal nucleus(Ep).A more homogenous plastic deformation with a weak loading-rate sensitivity of stress exponent is observed in the ultrasonic-vibrated sample,which coincides with the low pile-up and penetration depth as shown in the cross profile of indents.The structural rearrangement under resonance actuation demonstrated in this work might help us better understand the defect-activation mechanism for the plastic flow of amorphous systems.
文摘In this paper, high-zirconium Zr66＋2xAl9-x（Ni1/3Cu2/3）25-x （x=0,1,2 at.%） bulk metallic glasses with high strength and large duc- tility were fabricated by copper mould casting. The effects of zirconium content on the glass-forming ability （GFA）, thermal properties and mechanical properties were investigated using X-ray diffractometer （XRD）, differential scanning calorimeter （DSC）, and mechanical testing system in compressive and three-point bending modes, respectively. The high-zirconium BMGs show the critical diameters of 3-5 ram, the supercooled liquid region ranging from 70 K to 99 K, and the yield strength of over 1700 MPa. The Zr70Al7（Ni1/3Cu2/3）23 BMG exhibits a large compressive plastic strain up to 21% and a high notch toughness value of 60.6 MPa m1/2. The increase in Zr content results in the decrease in GFA and thermostability, and in the improvement of plasticity under compressive and three-point bending conditions. The superior plasticity of high-zirconium BMGs is at- tributed to their high Poisson＇s ratio and small elastic modulus ratioμl/B.
