Objective: To determine the effects of different strength of Murashige and Skoog(MS)media(full,1/2and1/4) in solid and liquid media on in vitro growth of Typhonium flagelliforme(T. flagelliforme), whereby an optimum m...Objective: To determine the effects of different strength of Murashige and Skoog(MS)media(full,1/2and1/4) in solid and liquid media on in vitro growth of Typhonium flagelliforme(T. flagelliforme), whereby an optimum media composition can be provided for mass propagation of T. flagelliforme.Methods: Rhizome bud of T. flagelliforme was obtained from the axenic in vitro established T. flagelliforme plantlets in Plant Tissue Culture Laboratory, Universiti Teknologi MARA, Shah Alam. Rhizome bud was used as explant and cultured onto shoot proliferation medium under different strength of MS media(full,1/2,1/4) in solid and liquid culture media.Results: After 6 weeks of culture, the number of shoot, number of leaf, number of root,height of shoot, fresh weight, dry weight and chlorophyll content of T. flagelliforme were analyzed. A comparison was made between liquid and solid culture media. The results revealed that the liquid culture media were more effective for all the growth parameters(shoot height, shoot number, leaf number, root number, fresh weight, dry weight, chlorophyll a and chlorophyll b content) compared to solid culture media. Apart from that,this study revealed the positive relationship between strength of MS media and type of culture media(solid and liquid media) to the growth of T. flagelliforme. Growth of T. flagelliforme was improved when MS strength was increased in liquid media. In contrast, growth of T. flagelliforme was improved when MS strength was decreased in solid media.Conclusions: Through this study, an optimum media composition for mass propagation of T. flagelliforme had been established by observing effects of MS media strength and type of culture media(solid and liquid media) on the growth of T. flagelliforme.展开更多
In this study, we measured the resistances (test frequency 837.8 Hz) of the paste of Portland cement (PC) and phosphoaluminate cement (PALC) subjected to different types of corrosion and different numbers of freeze-th...In this study, we measured the resistances (test frequency 837.8 Hz) of the paste of Portland cement (PC) and phosphoaluminate cement (PALC) subjected to different types of corrosion and different numbers of freeze-thaw cycles. This study aimed to improve understanding of the changing characteristics of paste resistance from both micro and macro perspectives by associating changes in the paste microstructure with changes in the paste mechanical strength using X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and other methods. Our results showed that changes in the paste resistance under the corrosive action of ambient media could signal the deterioration of paste structure and loss of paste strength. Continuous hydration reactions within the paste were found to render it more dense and increase its resistance. Invasion of corrosive ions was found to continue to increase paste resistance if the structure of the cement paste was not destroyed. Otherwise, paste resistance would decrease. Corrosive media were found to cause the dispersion of hydrated gels with certain degree of polymerization. Because spatial resistance was found to cause difficulty in the transportation of ion clusters, the decreases in resistance caused by long-term corrosion might be reduced due to a compensation effect. This effect was found to be related to the severity of structural damage to the paste. The magnitudes of corrosive effects of chemical media on the radicals in the cement paste structure were found to occur in the following order: SiO4 > AlO4 > PO4. The resistance and strength of the PC was always lower than those of PALC. In addition, losses of resistance and strength by PALC were mainly due to deterioration of the radical structure of AlO6.展开更多
The present paper aims at giving some general ideas concerning the micromechanical approach of the strength of a porous material. It is shown that its determination theoretically amounts to solving a nonlinear boundar...The present paper aims at giving some general ideas concerning the micromechanical approach of the strength of a porous material. It is shown that its determination theoretically amounts to solving a nonlinear boundary value problem defined on a representative elementary volume(REV). The principle of nonlinear homogenization is illustrated based on the case of a solid phase having a Green’s strength criterion. An original refinement of the so-called secant method(based on two reference strains) is also provided. The paper also describes the main feature of the Gurson’s model which implements the principle of limit analysis on a conceptual model of hollow sphere. The last part of the paper gives some ideas concerning poromechanical couplings.展开更多
基金Supported by Fundamental Research Grant Scheme with grant number(1/2014/STWN03/Ui TM/02/1)
文摘Objective: To determine the effects of different strength of Murashige and Skoog(MS)media(full,1/2and1/4) in solid and liquid media on in vitro growth of Typhonium flagelliforme(T. flagelliforme), whereby an optimum media composition can be provided for mass propagation of T. flagelliforme.Methods: Rhizome bud of T. flagelliforme was obtained from the axenic in vitro established T. flagelliforme plantlets in Plant Tissue Culture Laboratory, Universiti Teknologi MARA, Shah Alam. Rhizome bud was used as explant and cultured onto shoot proliferation medium under different strength of MS media(full,1/2,1/4) in solid and liquid culture media.Results: After 6 weeks of culture, the number of shoot, number of leaf, number of root,height of shoot, fresh weight, dry weight and chlorophyll content of T. flagelliforme were analyzed. A comparison was made between liquid and solid culture media. The results revealed that the liquid culture media were more effective for all the growth parameters(shoot height, shoot number, leaf number, root number, fresh weight, dry weight, chlorophyll a and chlorophyll b content) compared to solid culture media. Apart from that,this study revealed the positive relationship between strength of MS media and type of culture media(solid and liquid media) to the growth of T. flagelliforme. Growth of T. flagelliforme was improved when MS strength was increased in liquid media. In contrast, growth of T. flagelliforme was improved when MS strength was decreased in solid media.Conclusions: Through this study, an optimum media composition for mass propagation of T. flagelliforme had been established by observing effects of MS media strength and type of culture media(solid and liquid media) on the growth of T. flagelliforme.
文摘In this study, we measured the resistances (test frequency 837.8 Hz) of the paste of Portland cement (PC) and phosphoaluminate cement (PALC) subjected to different types of corrosion and different numbers of freeze-thaw cycles. This study aimed to improve understanding of the changing characteristics of paste resistance from both micro and macro perspectives by associating changes in the paste microstructure with changes in the paste mechanical strength using X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and other methods. Our results showed that changes in the paste resistance under the corrosive action of ambient media could signal the deterioration of paste structure and loss of paste strength. Continuous hydration reactions within the paste were found to render it more dense and increase its resistance. Invasion of corrosive ions was found to continue to increase paste resistance if the structure of the cement paste was not destroyed. Otherwise, paste resistance would decrease. Corrosive media were found to cause the dispersion of hydrated gels with certain degree of polymerization. Because spatial resistance was found to cause difficulty in the transportation of ion clusters, the decreases in resistance caused by long-term corrosion might be reduced due to a compensation effect. This effect was found to be related to the severity of structural damage to the paste. The magnitudes of corrosive effects of chemical media on the radicals in the cement paste structure were found to occur in the following order: SiO4 > AlO4 > PO4. The resistance and strength of the PC was always lower than those of PALC. In addition, losses of resistance and strength by PALC were mainly due to deterioration of the radical structure of AlO6.
文摘The present paper aims at giving some general ideas concerning the micromechanical approach of the strength of a porous material. It is shown that its determination theoretically amounts to solving a nonlinear boundary value problem defined on a representative elementary volume(REV). The principle of nonlinear homogenization is illustrated based on the case of a solid phase having a Green’s strength criterion. An original refinement of the so-called secant method(based on two reference strains) is also provided. The paper also describes the main feature of the Gurson’s model which implements the principle of limit analysis on a conceptual model of hollow sphere. The last part of the paper gives some ideas concerning poromechanical couplings.
