Color rendition,luminous efficacy and reliability are three key technical parameters for white light-emitting diodes(wLEDs)that are dominantly determined by down-conversion phosphors.However,there is usually an inevit...Color rendition,luminous efficacy and reliability are three key technical parameters for white light-emitting diodes(wLEDs)that are dominantly determined by down-conversion phosphors.However,there is usually an inevitable trade-off between color rendition and luminescence efficacy because the spectrum of red phosphor(that is,spectral broadness and position)cannot satisfy them simultaneously.In this work,we report a very promising red phosphor that can minimize the aforementioned trade-off via structure and band-gap engineering,achieved by introducing isostructural LiSi_(2)N_(3) into CaAlSiN_(3):Eu^(2+).The solid solution phosphors show both substantial spectra broadening(88→117 nm)and blueshift(652→642 nm),along with a significant improvement in thermal quenching(only a 6%reduction at 150℃),which are strongly associated with electronic and crystal structure evolutions.The broadband and robust red phosphor thus enables fabrication of super-high color rendering wLEDs(Ra=95 and R9=96)concurrently with the maintenance of a high-luminous efficacy(101 lm W^(−1)),validating its superiority in highperformance solid state lightings over currently used red phosphors.展开更多
Data from three cruises conducted in the Zhujiang River （ZR）, coastal waters of Guangdong （CWGD） and the northern South China Sea （NSCS） during 2003 and 2004 were examined for assessing the relative importance o...Data from three cruises conducted in the Zhujiang River （ZR）, coastal waters of Guangdong （CWGD） and the northern South China Sea （NSCS） during 2003 and 2004 were examined for assessing the relative importance of pigment composition and packaging effect in modifying the specific absorption coefficients of phytoplankton. The three survey regions differ widely in their phytoplankton community with large cells dominating the ZR and CWGD waters and small cells dominating the NSCS region. Variations in the size structure and the accessory pigments have much effect on the chlorophyll a-specific absorption coefficient of phytoplankton. The size index accounted for about 42% and 33% of the variation of the specific absorption coefficient at 440 and 675 nm, respectively. Using the multiple regression analysis approach, pigment concentrations for each sample were calculated. The accessory pigments other than chlorophyll a contribute to absorption mainly in the blue - to - green region of the spectrum and their absorptions account for about 44%, 43% and 53% on the average of the total phytoplankton absorption at 440 nm for the ZR, CWGD and NSCS regions. Among the accessory pigments, the photosynthetic carotenoids （noted PSC） play a dominant role in the ZR and CWGD waters, while in the NSCS the nonphotosynthetic carotenoids （noted PPG） as well as PSC have important contributions. Because the variations of both the size structure and accessory pigments in algal populations contributed to the variability of the specific absorption coefficient in the study regions, these factors may be considered explicitly in future bio - optical algorithms to derive chlorophyll a concentration more accurately.展开更多
This study presents a direct-writing structure color patterns on electrospun colloidal fibers by inkjet printing. The colloidal fiber was obtained by electrospinning the aqueous mixture of colloidal particles of poly(...This study presents a direct-writing structure color patterns on electrospun colloidal fibers by inkjet printing. The colloidal fiber was obtained by electrospinning the aqueous mixture of colloidal particles of poly(styrene-methyl methacrylate-acrylic acid) and poly(vinyl alcohol). The pattern was obtained by directly inkjet printing water onto the electrospun colloidal fiber. The pattern formation was attributed to the morphological transition of the colloidal fiber from the fiber aggregation to latex aggregation and the corresponding color change due to the dissolution of poly(vinyl alcohol) by water. Interestingly, a clear and clean image was successfully obtained on the ethanol-treated colloidal fibers film in comparison to a confused and blur image onto the freshly-made film. It is because the treatment process can compact the fiber structure and lower the spreading/wetting behavior of ink on the fiber structure, contributing to the formation of high-quality pattern. Various letters or quick response code were flexibly designed and printed on to colloidal fibers.Furthermore, the pattern can be easily transferred onto flexible substrate, i.e., a flexible printed bracelet. This work will be of great significance for the development of novel wearable functional materials/devices based on electrospun colloidal fibers.展开更多
基金the financial support from the JSPS KAKENHI(No.23560811)the National Natural Science Foundation of China(Nos.51272259,61575182,5157223 and 51561135015)+1 种基金the Natural Science Foundation of Zhejiang Province(No.Y16F050012)the Taiwan Science and Technology Authority(No.‘MOST’104-2113-M-002-012-MY3 and No.104-2119-M-002-027-MY3).
文摘Color rendition,luminous efficacy and reliability are three key technical parameters for white light-emitting diodes(wLEDs)that are dominantly determined by down-conversion phosphors.However,there is usually an inevitable trade-off between color rendition and luminescence efficacy because the spectrum of red phosphor(that is,spectral broadness and position)cannot satisfy them simultaneously.In this work,we report a very promising red phosphor that can minimize the aforementioned trade-off via structure and band-gap engineering,achieved by introducing isostructural LiSi_(2)N_(3) into CaAlSiN_(3):Eu^(2+).The solid solution phosphors show both substantial spectra broadening(88→117 nm)and blueshift(652→642 nm),along with a significant improvement in thermal quenching(only a 6%reduction at 150℃),which are strongly associated with electronic and crystal structure evolutions.The broadband and robust red phosphor thus enables fabrication of super-high color rendering wLEDs(Ra=95 and R9=96)concurrently with the maintenance of a high-luminous efficacy(101 lm W^(−1)),validating its superiority in highperformance solid state lightings over currently used red phosphors.
基金This work was supported by the National Natural Science Foundation of China under contract Nos 40476019,40576078 and 5210266the Knowledge Innovation Program of the Chinese Academy of Sciences under contract No.KZCX2-YW-215.
文摘Data from three cruises conducted in the Zhujiang River （ZR）, coastal waters of Guangdong （CWGD） and the northern South China Sea （NSCS） during 2003 and 2004 were examined for assessing the relative importance of pigment composition and packaging effect in modifying the specific absorption coefficients of phytoplankton. The three survey regions differ widely in their phytoplankton community with large cells dominating the ZR and CWGD waters and small cells dominating the NSCS region. Variations in the size structure and the accessory pigments have much effect on the chlorophyll a-specific absorption coefficient of phytoplankton. The size index accounted for about 42% and 33% of the variation of the specific absorption coefficient at 440 and 675 nm, respectively. Using the multiple regression analysis approach, pigment concentrations for each sample were calculated. The accessory pigments other than chlorophyll a contribute to absorption mainly in the blue - to - green region of the spectrum and their absorptions account for about 44%, 43% and 53% on the average of the total phytoplankton absorption at 440 nm for the ZR, CWGD and NSCS regions. Among the accessory pigments, the photosynthetic carotenoids （noted PSC） play a dominant role in the ZR and CWGD waters, while in the NSCS the nonphotosynthetic carotenoids （noted PPG） as well as PSC have important contributions. Because the variations of both the size structure and accessory pigments in algal populations contributed to the variability of the specific absorption coefficient in the study regions, these factors may be considered explicitly in future bio - optical algorithms to derive chlorophyll a concentration more accurately.
基金financial support by National Key R&D Program of China (Nos. 2016YFA0200803, 2017YFA0204 504, 2016YFB0402004)the National Natural Science Foundation of China (Nos. 51873221, 51673207, 51373183)
文摘This study presents a direct-writing structure color patterns on electrospun colloidal fibers by inkjet printing. The colloidal fiber was obtained by electrospinning the aqueous mixture of colloidal particles of poly(styrene-methyl methacrylate-acrylic acid) and poly(vinyl alcohol). The pattern was obtained by directly inkjet printing water onto the electrospun colloidal fiber. The pattern formation was attributed to the morphological transition of the colloidal fiber from the fiber aggregation to latex aggregation and the corresponding color change due to the dissolution of poly(vinyl alcohol) by water. Interestingly, a clear and clean image was successfully obtained on the ethanol-treated colloidal fibers film in comparison to a confused and blur image onto the freshly-made film. It is because the treatment process can compact the fiber structure and lower the spreading/wetting behavior of ink on the fiber structure, contributing to the formation of high-quality pattern. Various letters or quick response code were flexibly designed and printed on to colloidal fibers.Furthermore, the pattern can be easily transferred onto flexible substrate, i.e., a flexible printed bracelet. This work will be of great significance for the development of novel wearable functional materials/devices based on electrospun colloidal fibers.
