Reading is one of the most important skills to acquire language knowledge. Reading ability is the most important way of measuring one's language ability. Learning how to read is very important. For most teachers a...Reading is one of the most important skills to acquire language knowledge. Reading ability is the most important way of measuring one's language ability. Learning how to read is very important. For most teachers and students, it is also important to get a clear understanding of reading and reading ability and their relation. This article is just written to solve this problem and discuss the use of the multiple- choice in reading comprehension test.展开更多
A new method is introduced to measure the three parameters of shake quantity,multi-barrel parallelism and zero line using the synthesis of laser collimation,CCD graphic recognized technique and hydraulic press techniq...A new method is introduced to measure the three parameters of shake quantity,multi-barrel parallelism and zero line using the synthesis of laser collimation,CCD graphic recognized technique and hydraulic press technique.The paper describes briefly the principle of the equipment and analyzes the uncertainty.The uncertainty is not more than 15″.展开更多
Gd_3Ga_5O_ 12(GGG) was synthesized by a co-precipitation method using carbonate as precipitant. TG-DTA and IR spectra indicated that the precursor was alkaline. The weight loss was about 28% during sintering the precu...Gd_3Ga_5O_ 12(GGG) was synthesized by a co-precipitation method using carbonate as precipitant. TG-DTA and IR spectra indicated that the precursor was alkaline. The weight loss was about 28% during sintering the precursor. Sintering temperature was optimized according to XRD results and well-crystallized GGG was obtained by sintering at 1000 ℃ for 3 h. Compared with the solid-state reaction, the carbonate co-precipitation method had the merits of short reaction time, well-crystallization, lower sintering temperature and less volatilization. As a result, volatilization and disproportion of Gd_2O_3 and Ga_2O_3 might be controlled during GGG crystal growth.展开更多
Colloidal quantum dots(CQDs)are of interest for optoelectronic devices because of the possibility of high-throughput solution processing and the wide energy gap tunability from ultraviolet to infrared wavelengths.Peop...Colloidal quantum dots(CQDs)are of interest for optoelectronic devices because of the possibility of high-throughput solution processing and the wide energy gap tunability from ultraviolet to infrared wavelengths.People may question about the upper limit on the CQD wavelength region.To date,although the CQD absorption already reaches terahertz,the practical photodetection wavelength is limited within mid-wave infrared.To figure out challenges on CQD photoresponse in longer wavelength,would reveal the ultimate property on these nanomaterials.What’s more,it motivates interest in bottom-up infrared photodetection with less than 10%cost compared with epitaxial growth semiconductor bulk.In this work,developing a re-growth method and ionic doping modification,we demonstrate photodetection up to 18μm wavelength on HgTe CQD.At liquid nitrogen temperature,the responsivity reaches 0.3 A/W and 0.13 A/W,with specific detectivity 6.6×108 Jones and 2.3×109 Jones for 18μm and 10μm CQD photoconductors,respectively.This work is a step toward answering the general question on the CQD photodetection wavelength limitation.展开更多
文摘Reading is one of the most important skills to acquire language knowledge. Reading ability is the most important way of measuring one's language ability. Learning how to read is very important. For most teachers and students, it is also important to get a clear understanding of reading and reading ability and their relation. This article is just written to solve this problem and discuss the use of the multiple- choice in reading comprehension test.
文摘A new method is introduced to measure the three parameters of shake quantity,multi-barrel parallelism and zero line using the synthesis of laser collimation,CCD graphic recognized technique and hydraulic press technique.The paper describes briefly the principle of the equipment and analyzes the uncertainty.The uncertainty is not more than 15″.
文摘Gd_3Ga_5O_ 12(GGG) was synthesized by a co-precipitation method using carbonate as precipitant. TG-DTA and IR spectra indicated that the precursor was alkaline. The weight loss was about 28% during sintering the precursor. Sintering temperature was optimized according to XRD results and well-crystallized GGG was obtained by sintering at 1000 ℃ for 3 h. Compared with the solid-state reaction, the carbonate co-precipitation method had the merits of short reaction time, well-crystallization, lower sintering temperature and less volatilization. As a result, volatilization and disproportion of Gd_2O_3 and Ga_2O_3 might be controlled during GGG crystal growth.
基金Westlake Institute for Optoelectronics(No.2024GD003)National Natural Science Foundation of China(No.62105022,No.U22A2081)Beijing National Laboratory for Condensed Matter Physics(No.2023BNLCMPKF012).
文摘Colloidal quantum dots(CQDs)are of interest for optoelectronic devices because of the possibility of high-throughput solution processing and the wide energy gap tunability from ultraviolet to infrared wavelengths.People may question about the upper limit on the CQD wavelength region.To date,although the CQD absorption already reaches terahertz,the practical photodetection wavelength is limited within mid-wave infrared.To figure out challenges on CQD photoresponse in longer wavelength,would reveal the ultimate property on these nanomaterials.What’s more,it motivates interest in bottom-up infrared photodetection with less than 10%cost compared with epitaxial growth semiconductor bulk.In this work,developing a re-growth method and ionic doping modification,we demonstrate photodetection up to 18μm wavelength on HgTe CQD.At liquid nitrogen temperature,the responsivity reaches 0.3 A/W and 0.13 A/W,with specific detectivity 6.6×108 Jones and 2.3×109 Jones for 18μm and 10μm CQD photoconductors,respectively.This work is a step toward answering the general question on the CQD photodetection wavelength limitation.
