A new class of phosphor samples,denoted as Ba_(1-x)Al_(2)Ge_(2)O_(8):xEu^(2+)(BAGO:xEu^(2+))was synthesized using a Pechini-type sol-gel technique and subsequent thermal reduction in CO atmosphere.The morphology and s...A new class of phosphor samples,denoted as Ba_(1-x)Al_(2)Ge_(2)O_(8):xEu^(2+)(BAGO:xEu^(2+))was synthesized using a Pechini-type sol-gel technique and subsequent thermal reduction in CO atmosphere.The morphology and structural characteristics of both the BAGO host lattice and the Eu^(2+)ions activated BAGO phosphors were investigated through field-emission scanning electron microscopy and X-ray diffractometry analyses,respectively.The BAGO host lattice has micro-sized particles and the Rietveld refinement reveals the presence of a monoclinic crystal phase,characterized by the space group I2/c(No.15).Introducing Eu^(2+)ions into Ba^(2+)sites under CO condition reduces the particle size,switching from microscale to nanoscale.Within the near-ultraviolet spectrum(353 nm),the BAGO:xEu^(2+)phosphors exhibit a broadband bluish-green photoluminescence(PL)emission characterized by a peak band at 492 nm.This phenomenon is attributed to the 4f^(6)5d^(1)→4f^(7) electronic transition.The BAGO:0.02Eu^(2+)phosphor shows the strongest bluish-green PL emission,and a co mprehensive description of the concentration quenching mechanism between Eu^(2+)ions is revealed.Additionally,the thermal stability of the optimized BAGO:0.02Eu^(2+)phosphor was investigated,and its activation energy was estimated.Therefore,the synthesized bluish-green BAGO:0.02Eu^(2+)phosphor holds the promise of being a novel and potential candidate for utilization in white light-emitting diode applications.展开更多
Chlorine dioxide （OC10） is an important indicator for Cl-activation. The monitoring of OC10 appears to be crucial for understanding the chemistry of Cl-initialed oxidation and its impact on air quality in polluted c...Chlorine dioxide （OC10） is an important indicator for Cl-activation. The monitoring of OC10 appears to be crucial for understanding the chemistry of Cl-initialed oxidation and its impact on air quality in polluted coastal regions and industrialized areas. We report the development of a Xe arc lamp based near-ultraviolet （335-375 nm） incoherent broad- band cavity enhanced absorption spectroscopy （IBBCEAS） spectrometer for quantitative assessment of OC10 in an atmospheric simulation chamber. The important intermediate compound CH20, and other key atmospheric trace species （NO2） were also simultaneously measured. The instrumental performance shows a strong potential of this kind of IBBCEAS instrument for field and laboratory studies of atmospheric halogen chemistry.展开更多
Bipolaris oryzae is the causal agent of brown spot disease in rice and produces the dark pigment melanin. We isolated and characterized T4HR1 gene encoding 1,3,6,8-tetrahydroxynaphthalene (1,3,6,8-THN) reductase, whic...Bipolaris oryzae is the causal agent of brown spot disease in rice and produces the dark pigment melanin. We isolated and characterized T4HR1 gene encoding 1,3,6,8-tetrahydroxynaphthalene (1,3,6,8-THN) reductase, which converted 1,3,6,8-THN to scytalone in the melanin biosynthesis from B. oryzae. A sequence analysis showed that the T4HR1 gene encoded a putative protein of 268 amino acids showing 50% - 99% sequence identity to other fungal 1,3,6,8-THN reductases. Targeted disruption of the T4HR1 gene showed a different phenotype of mycelial color due to an accumulation of shunt products compared to those of wild-type on PDA plates using tricyclazole as a melanin biosynthesis inhibitor. A quantitative real-time PCR analysis showed that the expression of T4HR1 transcripts was enhanced by near-ultraviolet (NUV) irradiation and regulated by transcriptional factor BMR1, similar to three other melanin biosynthesis genes (polyketide synthase gene [PKS1], scytalone dehydratase gene [SCD1], and 1,3,8-THN reductase gene [THR1]) in the melanin biosynthesis of B. oryzae. These results suggested that common transcriptional mechanisms could regulate the enhanced gene expression of these melanin biosynthesis genes by NUV irradiation in B. oryzae.展开更多
Bipolaris oryzae is the causal agent of brown leaf spot disease in rice, and its asexual spore (conidium) formation is known to be induced by near-ultraviolet (NUV) irradiation. In order to reveal the photomorphogenic...Bipolaris oryzae is the causal agent of brown leaf spot disease in rice, and its asexual spore (conidium) formation is known to be induced by near-ultraviolet (NUV) irradiation. In order to reveal the photomorphogenic response and to identify new genes upregulated by NUV irradiation, suppression subtractive hybridization (SSH) was carried out in B. oryzae. To confirm the differential gene expression in NUV-irradiated mycelia, quantitative real-time PCR (qRT-PCR) analysis was performed among 301 genes arbitrarily chosen from 1170 cDNA clones. The expression of 46 genes (named NUV01 to NUV46) was found to be significantly enhanced (>4-fold) by NUV irradiation. Sequence analysis revealed that 23 out of the 46 sequences (50%) showed significant matches to known fungal genes. The 46 genes were categorized as either BLR1-dependent or BLR1-independent expression groups using the BLR1-deficient mutant, which presumably lacks the blue/UVA-absorbing photoreceptor. This finding demonstrates that NUV irradiation can induce gene regulation, and that this response may be mediated by both a blue/UVA-absorbing photoreceptor and an as-yet-unidentified photoreceptor in B. oryzae.展开更多
High-reflectivity Al-based n-electrode is used to enhance the luminescence properties of InGaN-based 395nm flip-chip near-ultraviolet （UV） light-emitting diodes. The Al-only metal layer could form the Ohmic contact ...High-reflectivity Al-based n-electrode is used to enhance the luminescence properties of InGaN-based 395nm flip-chip near-ultraviolet （UV） light-emitting diodes. The Al-only metal layer could form the Ohmic contact on the plasma etched n-GaN by means of chemical pre-treatment, with the lowest specific contact resistance of 2.211 × 10^-5 Ω. cm2. The AI n-electrodes enhance light output power of the 395 nm flip-chip near-UV light-emitting diodes by more than 33% compared with the Ti/AI n-electrodes. Meanwhile, the electrical characteristics of these chips with two types of n-electrodes do not show any significant discrepancy. The near-field light distribution measurement of packaged chips confirms that the enhanced luminescence is ascribed to the high refleetivity of the Al electrodes in the UV region. After the accelerated aging test for over 1000 h, the luminous degradation of the packaged chips with Al n-electrodes is less than 3%, which proves the reliability of these chips with the Al-based electrodes. Our approach shows a simplified design and fabrication of high-refleetivity n-electrode for flip-chip near-UV light emitting diodes.展开更多
Despite advances in the multicolor luminescence of Ce-activated materials,achieving efficient and stable near-ultraviolet(n-UV)emission remains a critical challenge.On the basis of structural rigidity engineering,a sm...Despite advances in the multicolor luminescence of Ce-activated materials,achieving efficient and stable near-ultraviolet(n-UV)emission remains a critical challenge.On the basis of structural rigidity engineering,a small Stokes shift(△S=0.53 eV)of Ce in microwave-hydrothermally synthesized NaSrY(PO_(4))_(2)(NSYP)nanophosphors is achieved,addressing this shortage.The internal quantum efficiency reaches as high as 98.5%(λ_(ex)=325 nm)along with superior thermostability(78%intensity retention at 423 K)andexceptional solvent resistance(82%after 10 days of immersion).The optimal nanomaterial is used as a scintillation screen for X-ray imaging,achieving a high spatial resolution of 11.0 Ip/mm and clear imaging of measured objects,rivaling a commercial scintillator(Cst:TI).A high relative sensitivity(S_(R-max)=0.94(%)-K^(-1))is achieved for excitation intensity ratio(EIR)technology-based opticall thermometry.This work presents fascinating applications in X-ray imaging and optical thermometry for n-UV-emittingl nanophosphors.These findings also highlight the critical role of host structure in designing high-quality Ce-activated optical materials.展开更多
在具有蓝宝石衬底的AlN模板上外延生长了近紫外In 0.01 Ga 0.99 N/Al 0.15 Ga 0.85 N多量子阱结构,对其荧光(PL)特性进行了测量。结果显示,该结构的PL峰位能量和线宽的温度行为分别呈“S”形(降低-增加-降低)和“W”形(变窄-变宽-变窄-...在具有蓝宝石衬底的AlN模板上外延生长了近紫外In 0.01 Ga 0.99 N/Al 0.15 Ga 0.85 N多量子阱结构,对其荧光(PL)特性进行了测量。结果显示,该结构的PL峰位能量和线宽的温度行为分别呈“S”形(降低-增加-降低)和“W”形(变窄-变宽-变窄-变宽),而其激发功率行为则分别呈“N”形(增加-降低-增加)和“V”形(变窄-变宽)。这些行为表明了该量子阱结构中载流子复合发光的局域特征和量子限制斯塔克效应的库伦屏蔽效应。前者被归因于阱厚起伏所导致的阱层内的势起伏,而后者则被归因于阱/垒晶格失配所诱发的极化电场。此外,该结构的积分PL强度的温度行为也证实了其阱层内局域深度的非均一性。展开更多
基金Project supported by the National Research Foundation of Korea Grant funded by the Korean government(MSIP)(2018R1A6A1A03025708)。
文摘A new class of phosphor samples,denoted as Ba_(1-x)Al_(2)Ge_(2)O_(8):xEu^(2+)(BAGO:xEu^(2+))was synthesized using a Pechini-type sol-gel technique and subsequent thermal reduction in CO atmosphere.The morphology and structural characteristics of both the BAGO host lattice and the Eu^(2+)ions activated BAGO phosphors were investigated through field-emission scanning electron microscopy and X-ray diffractometry analyses,respectively.The BAGO host lattice has micro-sized particles and the Rietveld refinement reveals the presence of a monoclinic crystal phase,characterized by the space group I2/c(No.15).Introducing Eu^(2+)ions into Ba^(2+)sites under CO condition reduces the particle size,switching from microscale to nanoscale.Within the near-ultraviolet spectrum(353 nm),the BAGO:xEu^(2+)phosphors exhibit a broadband bluish-green photoluminescence(PL)emission characterized by a peak band at 492 nm.This phenomenon is attributed to the 4f^(6)5d^(1)→4f^(7) electronic transition.The BAGO:0.02Eu^(2+)phosphor shows the strongest bluish-green PL emission,and a co mprehensive description of the concentration quenching mechanism between Eu^(2+)ions is revealed.Additionally,the thermal stability of the optimized BAGO:0.02Eu^(2+)phosphor was investigated,and its activation energy was estimated.Therefore,the synthesized bluish-green BAGO:0.02Eu^(2+)phosphor holds the promise of being a novel and potential candidate for utilization in white light-emitting diode applications.
基金This work was supported by the National Natural Science Foundation of China （No.41005017）, the Instrument Developing Project of the Chinese Academy of Sciences （No.YZ201121）, Jiangsu Provincial Natural Science Foundation of China （No.BK2011829）, and the Open Research Fund of Key Laboratory of Atmospheric Composition and Optical Radiation. The support of the Groupement de Recherche International SAMIA between CNRS （National Center for Scientific Research, France）, RFBR （Russian Foundation for Basic Research, Russia）, and CAS （Chinese Academy of Sciences, China） is acknowledged. We thank Dr. Albert A. Ruth at university college cork for the helpful discussion on the Xe lamp source based IBBCEAS.
文摘Chlorine dioxide （OC10） is an important indicator for Cl-activation. The monitoring of OC10 appears to be crucial for understanding the chemistry of Cl-initialed oxidation and its impact on air quality in polluted coastal regions and industrialized areas. We report the development of a Xe arc lamp based near-ultraviolet （335-375 nm） incoherent broad- band cavity enhanced absorption spectroscopy （IBBCEAS） spectrometer for quantitative assessment of OC10 in an atmospheric simulation chamber. The important intermediate compound CH20, and other key atmospheric trace species （NO2） were also simultaneously measured. The instrumental performance shows a strong potential of this kind of IBBCEAS instrument for field and laboratory studies of atmospheric halogen chemistry.
文摘Bipolaris oryzae is the causal agent of brown spot disease in rice and produces the dark pigment melanin. We isolated and characterized T4HR1 gene encoding 1,3,6,8-tetrahydroxynaphthalene (1,3,6,8-THN) reductase, which converted 1,3,6,8-THN to scytalone in the melanin biosynthesis from B. oryzae. A sequence analysis showed that the T4HR1 gene encoded a putative protein of 268 amino acids showing 50% - 99% sequence identity to other fungal 1,3,6,8-THN reductases. Targeted disruption of the T4HR1 gene showed a different phenotype of mycelial color due to an accumulation of shunt products compared to those of wild-type on PDA plates using tricyclazole as a melanin biosynthesis inhibitor. A quantitative real-time PCR analysis showed that the expression of T4HR1 transcripts was enhanced by near-ultraviolet (NUV) irradiation and regulated by transcriptional factor BMR1, similar to three other melanin biosynthesis genes (polyketide synthase gene [PKS1], scytalone dehydratase gene [SCD1], and 1,3,8-THN reductase gene [THR1]) in the melanin biosynthesis of B. oryzae. These results suggested that common transcriptional mechanisms could regulate the enhanced gene expression of these melanin biosynthesis genes by NUV irradiation in B. oryzae.
文摘Bipolaris oryzae is the causal agent of brown leaf spot disease in rice, and its asexual spore (conidium) formation is known to be induced by near-ultraviolet (NUV) irradiation. In order to reveal the photomorphogenic response and to identify new genes upregulated by NUV irradiation, suppression subtractive hybridization (SSH) was carried out in B. oryzae. To confirm the differential gene expression in NUV-irradiated mycelia, quantitative real-time PCR (qRT-PCR) analysis was performed among 301 genes arbitrarily chosen from 1170 cDNA clones. The expression of 46 genes (named NUV01 to NUV46) was found to be significantly enhanced (>4-fold) by NUV irradiation. Sequence analysis revealed that 23 out of the 46 sequences (50%) showed significant matches to known fungal genes. The 46 genes were categorized as either BLR1-dependent or BLR1-independent expression groups using the BLR1-deficient mutant, which presumably lacks the blue/UVA-absorbing photoreceptor. This finding demonstrates that NUV irradiation can induce gene regulation, and that this response may be mediated by both a blue/UVA-absorbing photoreceptor and an as-yet-unidentified photoreceptor in B. oryzae.
基金Supported by the National Key Research and Development Program of China under Grant Nos 2016YFB0400901 and2016YFB0400804the Key Laboratory of Infrared Imaging Materials and Detectors of Shanghai Institute of Technical Physics of Chinese Academy of Sciences under Grant NoⅡMDKFJJ-15-07+1 种基金the National Natural Science Foundation of China under Grant Nos 61675079,11574166 and 61377034the China Postdoctoral Foundation under Grant No 2016M602287
文摘High-reflectivity Al-based n-electrode is used to enhance the luminescence properties of InGaN-based 395nm flip-chip near-ultraviolet （UV） light-emitting diodes. The Al-only metal layer could form the Ohmic contact on the plasma etched n-GaN by means of chemical pre-treatment, with the lowest specific contact resistance of 2.211 × 10^-5 Ω. cm2. The AI n-electrodes enhance light output power of the 395 nm flip-chip near-UV light-emitting diodes by more than 33% compared with the Ti/AI n-electrodes. Meanwhile, the electrical characteristics of these chips with two types of n-electrodes do not show any significant discrepancy. The near-field light distribution measurement of packaged chips confirms that the enhanced luminescence is ascribed to the high refleetivity of the Al electrodes in the UV region. After the accelerated aging test for over 1000 h, the luminous degradation of the packaged chips with Al n-electrodes is less than 3%, which proves the reliability of these chips with the Al-based electrodes. Our approach shows a simplified design and fabrication of high-refleetivity n-electrode for flip-chip near-UV light emitting diodes.
基金supported by the Yunnan Fundamental Research Project(No.202401AS070128)the Yunnan Doctoral Student Service Industry Scientific Research and Innovation Cultivation Project(Nos.FWCY-BSPY2024028 and FWCYBSPY2024027)the National Natural Science Foundation of China(Nos.22165031 and 62475248).
文摘Despite advances in the multicolor luminescence of Ce-activated materials,achieving efficient and stable near-ultraviolet(n-UV)emission remains a critical challenge.On the basis of structural rigidity engineering,a small Stokes shift(△S=0.53 eV)of Ce in microwave-hydrothermally synthesized NaSrY(PO_(4))_(2)(NSYP)nanophosphors is achieved,addressing this shortage.The internal quantum efficiency reaches as high as 98.5%(λ_(ex)=325 nm)along with superior thermostability(78%intensity retention at 423 K)andexceptional solvent resistance(82%after 10 days of immersion).The optimal nanomaterial is used as a scintillation screen for X-ray imaging,achieving a high spatial resolution of 11.0 Ip/mm and clear imaging of measured objects,rivaling a commercial scintillator(Cst:TI).A high relative sensitivity(S_(R-max)=0.94(%)-K^(-1))is achieved for excitation intensity ratio(EIR)technology-based opticall thermometry.This work presents fascinating applications in X-ray imaging and optical thermometry for n-UV-emittingl nanophosphors.These findings also highlight the critical role of host structure in designing high-quality Ce-activated optical materials.
文摘在具有蓝宝石衬底的AlN模板上外延生长了近紫外In 0.01 Ga 0.99 N/Al 0.15 Ga 0.85 N多量子阱结构,对其荧光(PL)特性进行了测量。结果显示,该结构的PL峰位能量和线宽的温度行为分别呈“S”形(降低-增加-降低)和“W”形(变窄-变宽-变窄-变宽),而其激发功率行为则分别呈“N”形(增加-降低-增加)和“V”形(变窄-变宽)。这些行为表明了该量子阱结构中载流子复合发光的局域特征和量子限制斯塔克效应的库伦屏蔽效应。前者被归因于阱厚起伏所导致的阱层内的势起伏,而后者则被归因于阱/垒晶格失配所诱发的极化电场。此外,该结构的积分PL强度的温度行为也证实了其阱层内局域深度的非均一性。
