In-situ tensile testing in TEM (transmission electron microscopy) is a useful tool for studying mechanical properties of nano-structures because it can provide quanti-tative information on sample deformation at atomic...In-situ tensile testing in TEM (transmission electron microscopy) is a useful tool for studying mechanical properties of nano-structures because it can provide quanti-tative information on sample deformation at atomic scale. To facilitate in-situ TEM tensile tests of SCS (single crystal silicon) nanobeam, a MEMS tensile-testing chip was designed and fabricated. The chip was fabricated by means of bulk micro-machining and wafer bonding techniques. An SCS nanobeam, a comb drive ac-tuator, a force sensor beam and an electron beam window were integrated into the chip. With the on-chip comb-drive-actuator stretching the nanobeam and in-situ TEM observation, tensile test on a 90 nm-thick nanobeam was performed and the strain-stress relationship was obtained. The Young's modulus was fitted to be 161 GPa and did not show the size effect.展开更多
TEM-4 Oral Test is designed for second-year English majors in China to measure their English speaking skill.In this article,the author first gave an introduction to the purpose,format and content,and scoring criteria ...TEM-4 Oral Test is designed for second-year English majors in China to measure their English speaking skill.In this article,the author first gave an introduction to the purpose,format and content,and scoring criteria and procedures of the TEM-4 Oral Test.Then she evaluated the test on the aspects of validity,reliability and backwash.Though the test is feasible at present,it still has some problems in implementation.In the second section,the author also gave some advice on the improvement of the test.展开更多
基金the National Basic Research (973 Program) (Grant No. 2006CB300406)
文摘In-situ tensile testing in TEM (transmission electron microscopy) is a useful tool for studying mechanical properties of nano-structures because it can provide quanti-tative information on sample deformation at atomic scale. To facilitate in-situ TEM tensile tests of SCS (single crystal silicon) nanobeam, a MEMS tensile-testing chip was designed and fabricated. The chip was fabricated by means of bulk micro-machining and wafer bonding techniques. An SCS nanobeam, a comb drive ac-tuator, a force sensor beam and an electron beam window were integrated into the chip. With the on-chip comb-drive-actuator stretching the nanobeam and in-situ TEM observation, tensile test on a 90 nm-thick nanobeam was performed and the strain-stress relationship was obtained. The Young's modulus was fitted to be 161 GPa and did not show the size effect.
文摘TEM-4 Oral Test is designed for second-year English majors in China to measure their English speaking skill.In this article,the author first gave an introduction to the purpose,format and content,and scoring criteria and procedures of the TEM-4 Oral Test.Then she evaluated the test on the aspects of validity,reliability and backwash.Though the test is feasible at present,it still has some problems in implementation.In the second section,the author also gave some advice on the improvement of the test.
