A novel fluorene-based conjugated copolymer containing cyclobutenedione unit was synthesized by Suzuki reaction. Its structure and properties were characterized by FTIR, 1HNMR, elemental analysis, PL spectroscopy, DSC...A novel fluorene-based conjugated copolymer containing cyclobutenedione unit was synthesized by Suzuki reaction. Its structure and properties were characterized by FTIR, 1HNMR, elemental analysis, PL spectroscopy, DSC, TGA and cyclic voltammetry. The resulting polymer shows strong yellow PL emission (561 nm) and good solubility in polar aprotic solvents, i.e. THF, DMF, DMAC, DMSO, etc. DSC and TGA studies reveal that the novel polymer possesses excellent thermal stability with high glass transition temperature of 127℃ and onset decomposition temperature of 411℃. Cyclic voltammetry measurement demonstrated that the polymer has both hole and electron-transporting property.展开更多
Urbanization is a complex process reflecting the growth, formation and develop- ment of cities and their systems. Measuring regional urbanization levels within a long time series may ensure healthy and harmonious urba...Urbanization is a complex process reflecting the growth, formation and develop- ment of cities and their systems. Measuring regional urbanization levels within a long time series may ensure healthy and harmonious urban development. Based on DMSP/OLS night- time light data, a human-computer interactive boundary correction method was used to ob- tain information about built-up urban areas in the Bohai Rim region from 1992 to 2012. Con- sequently, a method was proposed and applied to measure urbanization levels using four measurement scale units： administrative division, land-sea location, terrain feature, and geomorphological types. Our conclusions are： 1） The extraction results based on DMSP/OLS nighttime light data showed substantial agreement with those obtained using Landsat TM/ETM＋ data on spatial patterns. The overall accuracy was 97.70% on average, with an average Kappa of 0.79, indicating that the results extracted from DMSP/OLS nighttime light data were reliable and could well reflect the actual status of built-up urban areas. 2） Bohai Rim＇s urbanization level has increased significantly, demonstrating a high annual growth rate from 1998 to 2006. Areas with high urbanization levels have relocated evidently from capital to coastal cities. 3） The distribution of built-up urban areas showed a certain degree of zonal variation. The urbanization level was negatively correlated with relief amplitude and altitude. A high level of urbanization was found in low altitude platforms and low altitude plains, with a gradual narrowing of the gap between these two geomorphological types. 4） The measure- ment method presented in this study is fast, convenient, and incorporates multiple perspec- tives. It would offer various directions for urban construction and provide reference values for measuring national-level urbanization.展开更多
Classical Mechanics using Einstein’s theories of relativity places a limit on speed as the speed of light. Quantum Mechanics has no such limitation. To understand space accelerating faster than the speed of light and...Classical Mechanics using Einstein’s theories of relativity places a limit on speed as the speed of light. Quantum Mechanics has no such limitation. To understand space accelerating faster than the speed of light and information being exchanged instantaneously between two entangled electrons separated by huge distances, one uses Planck’s length, Planck’s time, and Planck’s mass to indicate that space and time are discrete and therefore along with masses smaller than Planck’s mass are Quantum Mechanical in nature. Faster than the speed of light c = 3 × 10<sup>8</sup> m/s is a classical effect only in dimensions of space lower than our 3-D Universe, but it is a Quantum effect in all dimensions of space. Because space can oscillate sending out ripples from the source, it is the medium used for transporting light waves and gravity waves.展开更多
随着助产技术的发展,早产儿的生存率逐年上升。根据新生儿个性化发展护理和评估程序(newborn individualized developmental care and assessment program,NIDCAP)发育支持理论,光线对早产儿的健康和生长发育有重要的影响;然而由于治疗...随着助产技术的发展,早产儿的生存率逐年上升。根据新生儿个性化发展护理和评估程序(newborn individualized developmental care and assessment program,NIDCAP)发育支持理论,光线对早产儿的健康和生长发育有重要的影响;然而由于治疗的需要,难以在新生儿重症监护室(neonatal intensive care unit,NICU)内营造一个适合早产儿生长发育的光线环境。国外许多学会推荐在NICU内使用循环光线,且也有部分研究证实循环光线对早产儿生长发育的积极影响。因此,文章从循环光线的理论基础、定义、实施方法及其对早产儿生长发育的影响进行综述,以期为医护人员开展相关干预研究提供借鉴和指导。最后提出未来此类研究的发展方向,建议未来应进行更多设计良好且样本量足够大的研究,以明确循环光线的定义、优势及NICU内使用循环光线的有效性和必要性,其对早产儿长期的神经发育结果也值得随访探讨。展开更多
文摘A novel fluorene-based conjugated copolymer containing cyclobutenedione unit was synthesized by Suzuki reaction. Its structure and properties were characterized by FTIR, 1HNMR, elemental analysis, PL spectroscopy, DSC, TGA and cyclic voltammetry. The resulting polymer shows strong yellow PL emission (561 nm) and good solubility in polar aprotic solvents, i.e. THF, DMF, DMAC, DMSO, etc. DSC and TGA studies reveal that the novel polymer possesses excellent thermal stability with high glass transition temperature of 127℃ and onset decomposition temperature of 411℃. Cyclic voltammetry measurement demonstrated that the polymer has both hole and electron-transporting property.
基金Surveying and Mapping Geoinformation Nonprofit Specific Project,No.201512033National Natural Science Foundation of China,No.41171332+1 种基金Major State Basic Research Development Program of China,No.2015CB954101National Science Technology Basic Special Project,No.2011FY110400-2
文摘Urbanization is a complex process reflecting the growth, formation and develop- ment of cities and their systems. Measuring regional urbanization levels within a long time series may ensure healthy and harmonious urban development. Based on DMSP/OLS night- time light data, a human-computer interactive boundary correction method was used to ob- tain information about built-up urban areas in the Bohai Rim region from 1992 to 2012. Con- sequently, a method was proposed and applied to measure urbanization levels using four measurement scale units： administrative division, land-sea location, terrain feature, and geomorphological types. Our conclusions are： 1） The extraction results based on DMSP/OLS nighttime light data showed substantial agreement with those obtained using Landsat TM/ETM＋ data on spatial patterns. The overall accuracy was 97.70% on average, with an average Kappa of 0.79, indicating that the results extracted from DMSP/OLS nighttime light data were reliable and could well reflect the actual status of built-up urban areas. 2） Bohai Rim＇s urbanization level has increased significantly, demonstrating a high annual growth rate from 1998 to 2006. Areas with high urbanization levels have relocated evidently from capital to coastal cities. 3） The distribution of built-up urban areas showed a certain degree of zonal variation. The urbanization level was negatively correlated with relief amplitude and altitude. A high level of urbanization was found in low altitude platforms and low altitude plains, with a gradual narrowing of the gap between these two geomorphological types. 4） The measure- ment method presented in this study is fast, convenient, and incorporates multiple perspec- tives. It would offer various directions for urban construction and provide reference values for measuring national-level urbanization.
文摘Classical Mechanics using Einstein’s theories of relativity places a limit on speed as the speed of light. Quantum Mechanics has no such limitation. To understand space accelerating faster than the speed of light and information being exchanged instantaneously between two entangled electrons separated by huge distances, one uses Planck’s length, Planck’s time, and Planck’s mass to indicate that space and time are discrete and therefore along with masses smaller than Planck’s mass are Quantum Mechanical in nature. Faster than the speed of light c = 3 × 10<sup>8</sup> m/s is a classical effect only in dimensions of space lower than our 3-D Universe, but it is a Quantum effect in all dimensions of space. Because space can oscillate sending out ripples from the source, it is the medium used for transporting light waves and gravity waves.
文摘随着助产技术的发展,早产儿的生存率逐年上升。根据新生儿个性化发展护理和评估程序(newborn individualized developmental care and assessment program,NIDCAP)发育支持理论,光线对早产儿的健康和生长发育有重要的影响;然而由于治疗的需要,难以在新生儿重症监护室(neonatal intensive care unit,NICU)内营造一个适合早产儿生长发育的光线环境。国外许多学会推荐在NICU内使用循环光线,且也有部分研究证实循环光线对早产儿生长发育的积极影响。因此,文章从循环光线的理论基础、定义、实施方法及其对早产儿生长发育的影响进行综述,以期为医护人员开展相关干预研究提供借鉴和指导。最后提出未来此类研究的发展方向,建议未来应进行更多设计良好且样本量足够大的研究,以明确循环光线的定义、优势及NICU内使用循环光线的有效性和必要性,其对早产儿长期的神经发育结果也值得随访探讨。
文摘目的：评估6种LED固化灯光照射强度随光源距离的增加出现衰减的程度。方法：选择6种LED光固化灯：配置标准光导棒的Bluephase、Bluephase C8和Elipar S10,配置聚光透镜的Ascent PX,配置涡轮光导棒的Demi和Ti-Lite GT-1500。使用光强测量仪在距光源0、1、2、3、4、5 mm测量光固化灯的光照射强度,每一距离测量10次,并计算光强度平均值及相应的光强度衰减率。结果：6种固化灯初始光强度分别为859 m W/cm^2（Bluephase C8）、1 121 m W/cm^2（Bluephase）、1 133 m W/cm^2（Elipar S10）、1 300 m W/cm^2（Ascent PX）、1 497 m W/cm^2（Demi）和1 192 m W/cm^2（Ti-Lite）。除Ascent PX的1～3 mm光源距离外,光源距离每增加1 mm,6种固化灯的光照射强度均出现显著降低（P〈0.05）。距离光源5 mm时,只有Bluephase、Elipar S10和Ascent PX的光强度超过了400 m W/cm^2,光强度衰减率分别为56.7%、58.7%、53.8%,明显低于Bluephase C8（66%）、Demi（78.8%）和Ti-Lite（〉72.2%）。结论：临床中应尽可能选用高强度LED固化灯并延长照射时间以弥补光源距离增加所造成的光强度衰减,建议选择配置标准光导棒或聚光透镜的高强度LED光固化灯。
