With XAD-series and ion exchange resins, dissolved organic matter （DOM） from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid （HA）, fulvic acid （FA）, hydrophobic neutra...With XAD-series and ion exchange resins, dissolved organic matter （DOM） from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid （HA）, fulvic acid （FA）, hydrophobic neutrals （HON）, hydrophilic acids （HIA）, hydrophilic bases （HIB） and hydrophilic neutrals （HIN）. Those fractions were characterized by high performance size exclusion chromatography, fluorescence spectroscopy and UV absorbance. Among the 6 fractions, FA was predominant and accounted for 51% of the total DOM. The weight-average （Mw） and number-averaged （Mn） molecular weight of these fractions ranged from 1688 to 2355 Da and from 1338 to 1928 Da, respectively. A strong correlation was observed between specific UV absorbance at 280 nm, E2/E3 （absorbance at 250 nm to 365 nm）, and the molecular weight for DOM fractions. UV-Vis fulvic-like fluorescence peaks were found in all fractions. Proteinlike fluorescence peaks existed in HON may indicate that microbial activity was severely in Lake Hongfeng. There was a significant relationship between fluorescence intensities and specific UV absorbance at 254 nm for those DOM fractions, suggesting their similar luminescence characteristics. The values of fluorescence index （f450/500） indicated that hydrophobic fractions may derive from terrestrial sources, and the hydrophilic fractions from microbial and terrestrial origins. Those results suggest that there were inter-relationships between molecular weight, fluorescence and absorbance characteristics, and also subtle consistencies between the hydrophilic and hydrophobic properties and the sources for these 6 fractions from Lake Hongfeng.展开更多
Organic light-emitting diodes （OLEDs） have been extensively studied since the first efficient device based on small molecular luminescent materials was reported by Tang. Organic electroluminescent material, one of t...Organic light-emitting diodes （OLEDs） have been extensively studied since the first efficient device based on small molecular luminescent materials was reported by Tang. Organic electroluminescent material, one of the centerpieces of OLEDs, has been the focus of studies by many material scientists. To obtain high luminosity and to keep material costs low, a few remarkable design concepts have been developed. Aggregation-induced emission （AIE） materials were invented to overcome the common fluorescence-quenching problem, and cross-dipole stacking of fluorescent molecules was shown to be an effective method to get high solid-state luminescence. To exceed the limit of internal quantum efficiency of conventional fluorescent materials, phosphorescent materials were successfully applied in highly efficient electroluminescent devices. Most recently, delayed flu- orescent materials via reverse-intersystem crossing （RISC） from triplet to singlet and the ＂hot exciton＂ materials based on hy- bridized local and charge-transfer （HLCT） states were developed to he a new generation of low-cost luminescent materials as efficient as phosphorescent materials. In terms of the device-fabrication process, solution-processible small molecular lumi- nescent materials possess the advantages of high purity （vs. polymers） and low procession cost （vs. vacuum deposition）, which are garnering them increasing attention. Herein, we review the progress of the development of small-molecule luminescent materials with different design concepts and features, and also briefly examine future development tendencies of luminescent materials.展开更多
基金supported by the China’s Na-tional Basic Research Program (No. 2008CB418200)the National Knowledge Innovation Program of Chinese Academy of Sciences (No. kzcx2-yw-102)the Nation-al Natural Science Foundation of China (No. U0833603,40873079, 40703022).
文摘With XAD-series and ion exchange resins, dissolved organic matter （DOM） from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid （HA）, fulvic acid （FA）, hydrophobic neutrals （HON）, hydrophilic acids （HIA）, hydrophilic bases （HIB） and hydrophilic neutrals （HIN）. Those fractions were characterized by high performance size exclusion chromatography, fluorescence spectroscopy and UV absorbance. Among the 6 fractions, FA was predominant and accounted for 51% of the total DOM. The weight-average （Mw） and number-averaged （Mn） molecular weight of these fractions ranged from 1688 to 2355 Da and from 1338 to 1928 Da, respectively. A strong correlation was observed between specific UV absorbance at 280 nm, E2/E3 （absorbance at 250 nm to 365 nm）, and the molecular weight for DOM fractions. UV-Vis fulvic-like fluorescence peaks were found in all fractions. Proteinlike fluorescence peaks existed in HON may indicate that microbial activity was severely in Lake Hongfeng. There was a significant relationship between fluorescence intensities and specific UV absorbance at 254 nm for those DOM fractions, suggesting their similar luminescence characteristics. The values of fluorescence index （f450/500） indicated that hydrophobic fractions may derive from terrestrial sources, and the hydrophilic fractions from microbial and terrestrial origins. Those results suggest that there were inter-relationships between molecular weight, fluorescence and absorbance characteristics, and also subtle consistencies between the hydrophilic and hydrophobic properties and the sources for these 6 fractions from Lake Hongfeng.
文摘建立简单快速的金银花真伪分子鉴别方法。该研究依据金银花trn L-trn F 625位G/T SNP位点设计快速位点特异性PCR引物,优化位点特异性PCR条件,对金银花及其9种混淆品进行扩增及检测。当在87℃预变性1 min;87℃变性5s,68℃延伸5 s,30个循环时,通过加入SYBR Green I染料染色,金银花样品显绿色荧光,混淆品无荧光。整个PCR反应可在30 min内完成。该研究结果说明快速位点特异性PCR能简单快速鉴别金银花及其混淆品。
基金supported by the National Natural Science Foundation of China(21334002,51303057,51373054,91233113)the National Basic Research Program of China(2013CB834705,2014CB643504,2015CB655003)+1 种基金the Fundamental Research Funds for the Central Universities(2013ZZ0001)the Introduced Innovative R&D Team of Guangdong(201101C0105067115)
文摘Organic light-emitting diodes （OLEDs） have been extensively studied since the first efficient device based on small molecular luminescent materials was reported by Tang. Organic electroluminescent material, one of the centerpieces of OLEDs, has been the focus of studies by many material scientists. To obtain high luminosity and to keep material costs low, a few remarkable design concepts have been developed. Aggregation-induced emission （AIE） materials were invented to overcome the common fluorescence-quenching problem, and cross-dipole stacking of fluorescent molecules was shown to be an effective method to get high solid-state luminescence. To exceed the limit of internal quantum efficiency of conventional fluorescent materials, phosphorescent materials were successfully applied in highly efficient electroluminescent devices. Most recently, delayed flu- orescent materials via reverse-intersystem crossing （RISC） from triplet to singlet and the ＂hot exciton＂ materials based on hy- bridized local and charge-transfer （HLCT） states were developed to he a new generation of low-cost luminescent materials as efficient as phosphorescent materials. In terms of the device-fabrication process, solution-processible small molecular lumi- nescent materials possess the advantages of high purity （vs. polymers） and low procession cost （vs. vacuum deposition）, which are garnering them increasing attention. Herein, we review the progress of the development of small-molecule luminescent materials with different design concepts and features, and also briefly examine future development tendencies of luminescent materials.
