A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)...A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)∶Eu^(3+)can produce red mechanoluminescence,and importantly,it shows good repeatability.The mechanoluminescence of Ca_(5)Ga_(6)O_(14)∶Eu^(3+) results from the piezoelectric field generated inside the material under stress,rather than the charge carriers stored in the traps,which can be confirmed by the multiple cycles of mechanoluminescence tests and heat treatment tests.The mechanoluminescence color can be turned from red to green by co-doping varied concentrations of Tb^(3+),which may be meaningful for encrypted letter writing.The encryption scheme for secure communication was devised by harnessing mechanoluminescence patterns in diverse shapes and ASCII codes,which shows good encryption performance.The results suggest that the mechanoluminescence phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+),Tb^(3+)may be applied to the optical information encryption.展开更多
Eu^(2+) and Mn^(2+) co-activated CaAlSiN_(3) red phosphors were produced using the solid-state reaction tech⁃nique in a N2 environment.Excitation spectra,emission spectra,and diffuse reflection spectra were used to st...Eu^(2+) and Mn^(2+) co-activated CaAlSiN_(3) red phosphors were produced using the solid-state reaction tech⁃nique in a N2 environment.Excitation spectra,emission spectra,and diffuse reflection spectra were used to study the luminescence characteristics,energy gap,and thermal stability in detail.CaAlSiN_(3)∶Eu^(2+) exhibits an extended emission band when stimulated with 450 nm blue light,which is caused by the 4f65d to 4f7 transition of Eu^(2+).Similar⁃ly,CaAlSiN_(3)∶Mn^(2+) displays a wide emission band centered at 628 nm,which results from Mn^(2+)’s transition from 4T1(4G) to 6A1(6S).When the ions of Mn^(2+)were combined into CaAlSiN_(3)∶Eu^(2+),the photoluminescence intensity of Eu^(2+ )was greatly boosted because there was energy transfer and co-emission between Mn^(2+) and Eu^(2+).Beyond that,CaAlSiN_(3)∶Eu^(2+),Mn^(2+) emerges with splendid thermostability and high quantum efficiency,the quenching temperature surpasses 300℃,and the internal quantum efficiency is determined to be around 84.9%.The white LED was pack⁃aged with a combination of CaAlSiN_(3)∶Eu^(2+),Mn^(2+),LuAG∶Ce3+ and a blue chip.At a warm white-light corresponding color temperature(3009 K) with CIE coordinates(0.4223,0.3748),the color rendering index Ra has reached 93.2.CaAlSiN_(3)∶Eu^(2+),Mn^(2+) would have great application potential as a red-emitting phosphor for white LEDs.展开更多
The Eu^3＋ activated Lu2MoO6 phosphors were synthesized by high-temperature solid-state reaction method. The X-ray diffraction （XRD）, excitation spectra, emission spectra and decay lifetime of the phosphors were me...The Eu^3＋ activated Lu2MoO6 phosphors were synthesized by high-temperature solid-state reaction method. The X-ray diffraction （XRD）, excitation spectra, emission spectra and decay lifetime of the phosphors were measured to characterize the structure and luminescent properties. The XRD results show that all the prepared phosphors can be assigned to the monoclinic structure. The experimental results indicate efficient absorption of near ultraviolet light from the Mo^6＋O^2- group followed by intensive emission in the visible spectral range. The optimal content of Eu3＋ is 10% （mole fraction）. The critical distance Rc and energy transfer mechanism were also discussed in detail. This red emitting material may be applied as a promising red phosphor for the near ultraviolet excited white light emitting diodes.展开更多
Well-crystallized with excellent luminescent cessfully synthesized by a simple solid-state properties, Tb（BO2）3 nanorods were first suc- method with Ag as catalyst. The result of X- ray diffraction showed that the T...Well-crystallized with excellent luminescent cessfully synthesized by a simple solid-state properties, Tb（BO2）3 nanorods were first suc- method with Ag as catalyst. The result of X- ray diffraction showed that the Tb（BO2）3 nanorods could be well-crystallized at 700 ℃. As-prepared straight nanorods of Tb（BO2）3 had the typical diameters in the range of 100-200 nm, the thickness of 30 50 nm, and the length up to 3 μm by transmission electron microscopy, and the corresponding selected area electron diffraction indicated that the nanorod calcined at 700 ℃ was single-crystalline. Based on the fact that Ag nanoparticles attached to the tips and middles of the Tb（BO2）3 nanorods, a growth model of the Tb（BO2）3 nanorods was proposed. Photoluminescence spectra under excitation at 369 nm showed that these Tb（BO2）3 phosphors had a green emission at 546 nm, which is ascribed to 5D4→7F5 transition. The effect of calcining temperature on the structures, morphologies, and luminescent properties of Tb（BO2）3 phosphors were studied.展开更多
Green fluorescent protein (GFP) fused to the F_actin binding domain of mouse talin labels the actin cytoskeleton in the immature pollen of stable transformed rice (Oryza sativa L.) plants. Actin microfilaments could b...Green fluorescent protein (GFP) fused to the F_actin binding domain of mouse talin labels the actin cytoskeleton in the immature pollen of stable transformed rice (Oryza sativa L.) plants. Actin microfilaments could be visualized only in the late_developmental stage of the immature pollen. During this developmental stage, microfilaments, initially composed of very short fibrils, develop into a very complex and novel network that sometimes totally and sometimes partially encloses the vegetative nucleus and the spherical shaped generative cell in the central cytoplasm of the immature pollen. The behavior of the actin microfilamentous structure throughout the late_developmental stage of the immature pollen is extremely dynamic, and the likelihood of this structure in generating forces for vegetative nucleus and generative cell movement in the immature pollen has been discussed. No actin filaments were visualized in the spherical generative cells.展开更多
Green fluorescent protein (GFP) fused to the F-actin binding domain of mouse talin labels the actin cytoskeleton in the living generative and sperm cells of a third generation transgenic rice (Oryza sativa L.) plant, ...Green fluorescent protein (GFP) fused to the F-actin binding domain of mouse talin labels the actin cytoskeleton in the living generative and sperm cells of a third generation transgenic rice (Oryza sativa L.) plant, A005-G-T-1-2. Observations were made on pollen at four major developmental stages, viz. I. uni-nucleate microspore stage; II. early bi-cellular pollen stage; III. late bi-cellular pollen stage; and IV. tri-cellular pollen stage. At each of these developmental stages vegetative nucleus, generative nucleus/ cell, and sperm cells were seen undergoing continuous and coordinated motion and migration. These movements seemed to be influenced by associated microfilament networks existing in the pollen. Based on these observations we propose that it is the interaction between the microfilament networks (usually one existing in the central cytoplasm and another in the cortex) that controls the dynamic movement of the vegetative nucleus, generative nucleus/cell and sperm cells. Furthermore, we have also observed that there is an array of microfilaments (oriented mostly parallel to the long axis of the cell) existing in the generative and sperm cells. As far as we are aware, this is the first report showing the existence of microfilaments in living generative and sperm cells of rice pollen. The implication and significance of the existence of microfilaments in generative and sperm cells in rendering self-propelled motion of these cells in relation to their passage and movement in the pollen tube and embryo sac for fertilization were discussed.展开更多
Using density functional theory, we studied band structure, density of states, optical proper- ties and Mulliken population of the pure and SiN doped BaMgAl10017：Eu^2＋ （BAM：Eu^2＋） phosphors. Calculation results ...Using density functional theory, we studied band structure, density of states, optical proper- ties and Mulliken population of the pure and SiN doped BaMgAl10017：Eu^2＋ （BAM：Eu^2＋） phosphors. Calculation results showed that the bands of BAM：Eu2＋ were of low band energy dispersion, indicating large joint density of states, hence high performance of optical absorption and luminescence. BAM：Eu^2＋ showed stronger absorption intensity while Eu^2＋ occupied the BR sites instead of the mO sites. The concentration of Eu^2＋ at BR sites increased while that at mO sites decreased after Si-N doping. The influence of the variation of Eu^2＋ distribution on the spectra was stronger than the influence of the decrease of Eu^2＋ PDOS when SiN concentration was lower than 0.25, therefore the absorption and luminescence intensity of BAM：Eu^2＋ were enhanced. Mulliken population of Si-N bond was higher than A1-O bond, while that of Eu-N bond was higher than Eu-O bond as well, indicating that Si-N bonds and Eu-N bonds possessed higher covalence than Al-O bonds and Eu-N bonds respectively. The existence of Si-N bonds and Eu-N bonds enhanced the local covalence of Eu^2＋, hence the optical stability of BAM：Eu^2＋.展开更多
Objective To investigate the proteolytic mechanism of amyloid precursor protein （APP） and to explore amyloidbeta （Aβ） generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The ...Objective To investigate the proteolytic mechanism of amyloid precursor protein （APP） and to explore amyloidbeta （Aβ） generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The four fragments, CFP, 54bp, YFP and C99 were ligated into pcDNA3.0 vector to construct the recombinant plasmids pcDNA3.0-CFP-54bp- YFP and pcDNA3.0-CFP-54bp-YFP-C99. The SH-SY5Y cells were transiently transfected with pcDNA3.0-CFP-54bp-YFP or pcDNA3.0-CFP-54bp-YFP-C99. The expression of fusion gene was examined under a multiphoton laser scanning microscope. Fluorescence resonance energy transfer （FRET） was used to measure the β cleavage and γ cleavage of APE Aβ generation was confirmed by immunocytochemistry and multiphoton laser scanning microscopy. Cell viability was tested by MTT assay at different time points. Results （1） The double restriction endonuclease digestion and sequencing analysis confirmed the authenticity of the recombinant plasmids pcDNA3.0-CFP-54bp-YFP and pcDNA3.0-CFP-54bp- YFP-C99. （2） Blue and yellow fluorescences were detected in the transfected cells. （3） FRET occurred in pcDNA3.0-CFP- 54bp-YFP-transfected cells but not in pcDNA3.0-CFP-54bp-YFP-C99-transfected cells. （4） Aβ was produced in the pcDNA3.0- CFP-54bp-YFP-C99 transfected cells. （5） Aβ-deposition was widespread in the cell. （6） Cell viability decreased along with the intracellular Aβ deposition. Conclusion C99 is important for the APP β cleavage. Aβ may be generated and deposited in cells at the early stage of Alzheimer＇s disease. Intracellular Aβ accumulation brings deleterious effects on cells.展开更多
CaCO3 was chosen as main raw material and Solid State method was used to prepare the sample. The precursor was directly sintered at 1100 ℃ with reducing atmosphere for 3 h to obtain new green CaO：Tb^3＋, Li^＋ Phosp...CaCO3 was chosen as main raw material and Solid State method was used to prepare the sample. The precursor was directly sintered at 1100 ℃ with reducing atmosphere for 3 h to obtain new green CaO：Tb^3＋, Li^＋ Phosphors. The effects of the content of the doping ions Tb^3＋ on the luminescent properties have been studied. The structure, morphology and luminescent properties of the phosphors were characterized by XRD, SEM, UV and PL-PLE spectra respectively. The results showed that the CaO：Tb^3＋, Li^＋ was a single face-centered cubic crystals, the phosphor particle distributed uniformly. The phosphor has a strong absorptive capacity excited by 282 nm ultraviolet ray, and could emit the strong green light with the wavelength of 543 nm （^5D4→^7F5）. The CaO：Tb^3＋, Li^＋ is a new type of green fluorescent material.展开更多
The simple approach to acquire the fltaxescenee spectra of vitamin bl, b2 and t6 is proposed by direct ilhanination on solid powder sample. The experimentally acquired fluorescence spectra are in accordance with the p...The simple approach to acquire the fltaxescenee spectra of vitamin bl, b2 and t6 is proposed by direct ilhanination on solid powder sample. The experimentally acquired fluorescence spectra are in accordance with the previous measurements on soluble samples. The fluorescence spectra for a mixture of vitamins bl, b2 and b6 with different concentrations have been investigated, and the fluorescence mechanism is explained on the basis of moleoalar struchture Possible reasons of the blue-shift of the fluorescence peak and enhancement of the peak power are explained as well. The advantages of solid powder method is analyzed and discussed.展开更多
The extraction of Eu^(3+)from chloride medium using bifunctional ionic liquid extractants(Bif-ILEs)tri-n-octylmethyl ammonium bis(2-ethyl hexyl)phosphate([A336][D2EHP])and trihexyltetradecyl phosphonium bis(2-ethylhex...The extraction of Eu^(3+)from chloride medium using bifunctional ionic liquid extractants(Bif-ILEs)tri-n-octylmethyl ammonium bis(2-ethyl hexyl)phosphate([A336][D2EHP])and trihexyltetradecyl phosphonium bis(2-ethylhexyl)phosphate([P_(66614)][D2EHP])in kerosene was studied to develop environmentally friendly extraction process.The extraction behavior of Eu^(3+)was examined by varying key process parameters.The extraction behavior indicates that ammonium-based ionic liquid[A336][D2EHP]shows better extraction efficiency of Eu^(3+)than that of phosphonium-based ionic liquid[P_(66614)][D2EHP].Quantitative extraction of Eu^(3+)is obtained with 0.05 mol/L[A336][D2EHP],whereas,0.1 mol/L of[P_(66614)][D2EHP]is required to achieve the same extraction rate of Eu^(3+).The extraction process is endothermic with respect to[A336][D2EHP].Stripping experiments indicate that 100%of Eu^(3+)can be back extracted from both the loaded ionic liquids using 20 vol.%HNO_(3).The highest separation factor(βY/Eu)of 653.59 is reported at pH of 3.2,and the separation factor of Eu^(3+)over La^(3+)is 30.6 at the same pH.From the leach liquors of waste tube light powder,99.98%of Eu and 99.99%Y are recovered using 0.2 mol/L[A336][D2EHP]in 2-stage cross current extraction with aqueous to organcic ratio(O/A)of 1:1 and 1:2.展开更多
Phosphor yttrium aluminum garnet Y3A15O12 （YAG）, activated with trivalent cerium （Ce^3＋）, was synthesized by T-tube impinging streams, T-type vortex impinging streams co-precipitation method （IS-CP） and direct ...Phosphor yttrium aluminum garnet Y3A15O12 （YAG）, activated with trivalent cerium （Ce^3＋）, was synthesized by T-tube impinging streams, T-type vortex impinging streams co-precipitation method （IS-CP） and direct co-precipitation method （D-CP）, respectively. The crystallization, morphologies, particle size and particle size distribution of the phosphors obtained under different experimental conditions were studied. The influence of various factors on the luminescence intensity of the phosphor was also investigated, such as feeding methods, volume flow rate, contents of Ce and initial reactant concentration. The results show that the precursors synthesized by T-tube impinging streams co-precipitation reaction transform to Y3A15O12 （YAG） phosphor at about 1 000 ℃. The particles are far smaller and narrower than those prepared by D-CP. In the impinging streams co-precipitation system, the luminescent intensity of YAG：Ce phosphor increases with the increase of liquid flow rate. The intensity firstly increases then decreases with the increasing Ce^3＋ doping content, and the maximum intensity is shown at 1.67% （molar fraction） Ce. Luminescent intensity gradually decreases with the increase of initial concentration of reactants. At the same operational condition, the luminescent intensity of the phosphors prepared by T-tube impinging streams reactor is higher than that by D-CP, and the luminescent intensity of the phosphors prepared by T-type vortex impinging streams is higher than that by T-tube impinging streams reactor.展开更多
A highly intense green-emitting phosphor of Eu2＋-doped Sr4Al14O25 （SAE：Eu2＋） was synthesized by a solid state reaction. In this study, XRD, PL/PLE, QE, thermal stability and LED package tests are systematically c...A highly intense green-emitting phosphor of Eu2＋-doped Sr4Al14O25 （SAE：Eu2＋） was synthesized by a solid state reaction. In this study, XRD, PL/PLE, QE, thermal stability and LED package tests are systematically carried out and investigated. The optimized-composition of （Sro 92Eu0.08）4Al14025 exhibited a green emission peak at 497 nm under excitation wavelength of 400 nm, giving the chromaticity coordinates of （0.14, 0.35） with excellent quantum efficiency （98%） compared to those of other green-commodities, such as Ba2SiO4：Eu2＋ （90%） and BaMgAl10O17：EU2＋, Mn2＋ （92%）. The results demonstrated that SAE：Eu2＋ could be a potential candidate as the NUV-pumping phosphor for applications in light-emitting diodes （LEDs）.展开更多
Magnetic starch particles （MSPs） were synthesized in water-in-oil mieroemulsion at room temperature. MSPs were characterized by transmission electron microscopy （TEM）, Fourier transform infrared spectrometry （FTI...Magnetic starch particles （MSPs） were synthesized in water-in-oil mieroemulsion at room temperature. MSPs were characterized by transmission electron microscopy （TEM）, Fourier transform infrared spectrometry （FTIR）, zeta potential system, thermogravimetric analysis （TGA） and vibrating sample magnetometry （VSM）. The average diameter of the MSPs was 220 nm, dispersed with well-proportioned size and magnetic resonance, the saturation magnetization was 3.64 A.mR/kg. MSP was coated with poly-L-lysine （PLL）, and then the surface of PLL-MSP was combined with fluorescein isothiocynate （FITC）. Results show that fluorescent/magnetic starch particles （FMSPs） are of stable photo-bleaching capability compared with free FITC, with low bio-toxicity and certain function of magnetic separation. It is expected that FMSPs are bifimctional nano-materials including fluorescence labelling and magnetic separation.展开更多
In order to study the effects of ionic surfactants on bacterial luciferase,the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison ...In order to study the effects of ionic surfactants on bacterial luciferase,the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison with bacterial luciferase,α-amylase was used since these two enzymes have similar electrostatic potential and charged active sites.After the enzymes were treated with the surfactants,the catalytic properties of bacterial luciferase andα-amylase were assayed,and fluorescence spectroscopy and circular dichroism (CD) were used to analyze the alteration of the protein structure.The results showed that when the DTAB concentration was low,the cationic surfactant DTAB enhanced the enzymatic activities of bacterial luciferase andα-amylase.On the other hand,the anionic surfactant SDS did not alter the enzymatic activity.The main interaction of cationic surfactant DTAB and the negatively charged surface of the proteins was the ionic interaction,which could alter the environment for the enzyme to work when the DTAB/enzyme molar ratio was low.However,at high cationic surfactant concentration,the ionic interaction and hydrophobic interaction might destroy the secondary and tertiary structures of the proteins,leading to the loss of enzymatic activities.展开更多
A green-emitting phosphor Ca（Tb1-xLax）4（SiO4）3O （CTLS） was synthesized by a solid state reaction. X-ray diffraction, photoluminescence （PL） spectroscopy, reflectance spectra and chromaticity coordinates were c...A green-emitting phosphor Ca（Tb1-xLax）4（SiO4）3O （CTLS） was synthesized by a solid state reaction. X-ray diffraction, photoluminescence （PL） spectroscopy, reflectance spectra and chromaticity coordinates were carried out in this study. The CaTb4（SiO4）3O host has been known to crystallize in a hexagonal structure with disordering found in the Ca2＋ and Tb3＋ cation sites. The phosphors exhibited highly green-emitting band centered at 541 nm under ultraviolet excitation, which corresponds to the 5D4→7F5 transition. The optimal doping concentration of Tb3＋ was observed to be at 20 mol%, and the PL intensity was found to decline dramatically when the content of Tb3＋ exceeds 20m01% due to concentration quenching. Based on the results, we are currently evaluating the potential application of Ca（Tb,La）4（SiO4）30 as a new green-emitting near-UV LED convertible phosphor.展开更多
文摘A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)∶Eu^(3+)can produce red mechanoluminescence,and importantly,it shows good repeatability.The mechanoluminescence of Ca_(5)Ga_(6)O_(14)∶Eu^(3+) results from the piezoelectric field generated inside the material under stress,rather than the charge carriers stored in the traps,which can be confirmed by the multiple cycles of mechanoluminescence tests and heat treatment tests.The mechanoluminescence color can be turned from red to green by co-doping varied concentrations of Tb^(3+),which may be meaningful for encrypted letter writing.The encryption scheme for secure communication was devised by harnessing mechanoluminescence patterns in diverse shapes and ASCII codes,which shows good encryption performance.The results suggest that the mechanoluminescence phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+),Tb^(3+)may be applied to the optical information encryption.
文摘Eu^(2+) and Mn^(2+) co-activated CaAlSiN_(3) red phosphors were produced using the solid-state reaction tech⁃nique in a N2 environment.Excitation spectra,emission spectra,and diffuse reflection spectra were used to study the luminescence characteristics,energy gap,and thermal stability in detail.CaAlSiN_(3)∶Eu^(2+) exhibits an extended emission band when stimulated with 450 nm blue light,which is caused by the 4f65d to 4f7 transition of Eu^(2+).Similar⁃ly,CaAlSiN_(3)∶Mn^(2+) displays a wide emission band centered at 628 nm,which results from Mn^(2+)’s transition from 4T1(4G) to 6A1(6S).When the ions of Mn^(2+)were combined into CaAlSiN_(3)∶Eu^(2+),the photoluminescence intensity of Eu^(2+ )was greatly boosted because there was energy transfer and co-emission between Mn^(2+) and Eu^(2+).Beyond that,CaAlSiN_(3)∶Eu^(2+),Mn^(2+) emerges with splendid thermostability and high quantum efficiency,the quenching temperature surpasses 300℃,and the internal quantum efficiency is determined to be around 84.9%.The white LED was pack⁃aged with a combination of CaAlSiN_(3)∶Eu^(2+),Mn^(2+),LuAG∶Ce3+ and a blue chip.At a warm white-light corresponding color temperature(3009 K) with CIE coordinates(0.4223,0.3748),the color rendering index Ra has reached 93.2.CaAlSiN_(3)∶Eu^(2+),Mn^(2+) would have great application potential as a red-emitting phosphor for white LEDs.
基金Project(11404047)supported by the National Natural Science Foundation of ChinaProjects(CSTC2015jcyj A50005,CSTC2014JCYJA50034)supported by the Natural Science Foundation Project of Chongqing,ChinaProject(KJ1500412,KJ1500409)supported by Scientific and Technological Research Program of Chongqing Municipal Education Commission,China
文摘The Eu^3＋ activated Lu2MoO6 phosphors were synthesized by high-temperature solid-state reaction method. The X-ray diffraction （XRD）, excitation spectra, emission spectra and decay lifetime of the phosphors were measured to characterize the structure and luminescent properties. The XRD results show that all the prepared phosphors can be assigned to the monoclinic structure. The experimental results indicate efficient absorption of near ultraviolet light from the Mo^6＋O^2- group followed by intensive emission in the visible spectral range. The optimal content of Eu3＋ is 10% （mole fraction）. The critical distance Rc and energy transfer mechanism were also discussed in detail. This red emitting material may be applied as a promising red phosphor for the near ultraviolet excited white light emitting diodes.
文摘Well-crystallized with excellent luminescent cessfully synthesized by a simple solid-state properties, Tb（BO2）3 nanorods were first suc- method with Ag as catalyst. The result of X- ray diffraction showed that the Tb（BO2）3 nanorods could be well-crystallized at 700 ℃. As-prepared straight nanorods of Tb（BO2）3 had the typical diameters in the range of 100-200 nm, the thickness of 30 50 nm, and the length up to 3 μm by transmission electron microscopy, and the corresponding selected area electron diffraction indicated that the nanorod calcined at 700 ℃ was single-crystalline. Based on the fact that Ag nanoparticles attached to the tips and middles of the Tb（BO2）3 nanorods, a growth model of the Tb（BO2）3 nanorods was proposed. Photoluminescence spectra under excitation at 369 nm showed that these Tb（BO2）3 phosphors had a green emission at 546 nm, which is ascribed to 5D4→7F5 transition. The effect of calcining temperature on the structures, morphologies, and luminescent properties of Tb（BO2）3 phosphors were studied.
文摘Green fluorescent protein (GFP) fused to the F_actin binding domain of mouse talin labels the actin cytoskeleton in the immature pollen of stable transformed rice (Oryza sativa L.) plants. Actin microfilaments could be visualized only in the late_developmental stage of the immature pollen. During this developmental stage, microfilaments, initially composed of very short fibrils, develop into a very complex and novel network that sometimes totally and sometimes partially encloses the vegetative nucleus and the spherical shaped generative cell in the central cytoplasm of the immature pollen. The behavior of the actin microfilamentous structure throughout the late_developmental stage of the immature pollen is extremely dynamic, and the likelihood of this structure in generating forces for vegetative nucleus and generative cell movement in the immature pollen has been discussed. No actin filaments were visualized in the spherical generative cells.
文摘Green fluorescent protein (GFP) fused to the F-actin binding domain of mouse talin labels the actin cytoskeleton in the living generative and sperm cells of a third generation transgenic rice (Oryza sativa L.) plant, A005-G-T-1-2. Observations were made on pollen at four major developmental stages, viz. I. uni-nucleate microspore stage; II. early bi-cellular pollen stage; III. late bi-cellular pollen stage; and IV. tri-cellular pollen stage. At each of these developmental stages vegetative nucleus, generative nucleus/ cell, and sperm cells were seen undergoing continuous and coordinated motion and migration. These movements seemed to be influenced by associated microfilament networks existing in the pollen. Based on these observations we propose that it is the interaction between the microfilament networks (usually one existing in the central cytoplasm and another in the cortex) that controls the dynamic movement of the vegetative nucleus, generative nucleus/cell and sperm cells. Furthermore, we have also observed that there is an array of microfilaments (oriented mostly parallel to the long axis of the cell) existing in the generative and sperm cells. As far as we are aware, this is the first report showing the existence of microfilaments in living generative and sperm cells of rice pollen. The implication and significance of the existence of microfilaments in generative and sperm cells in rendering self-propelled motion of these cells in relation to their passage and movement in the pollen tube and embryo sac for fertilization were discussed.
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.51072191）, One Hundred Talents Program of the Chinese Academy of Sciences, the National Basic Research Program of China （No.2012CB922004）, the National Natural Science Foundation of China （No.11105133）, and USTC- NSRL Association Funding （No.KY2060140005）.
文摘Using density functional theory, we studied band structure, density of states, optical proper- ties and Mulliken population of the pure and SiN doped BaMgAl10017：Eu^2＋ （BAM：Eu^2＋） phosphors. Calculation results showed that the bands of BAM：Eu2＋ were of low band energy dispersion, indicating large joint density of states, hence high performance of optical absorption and luminescence. BAM：Eu^2＋ showed stronger absorption intensity while Eu^2＋ occupied the BR sites instead of the mO sites. The concentration of Eu^2＋ at BR sites increased while that at mO sites decreased after Si-N doping. The influence of the variation of Eu^2＋ distribution on the spectra was stronger than the influence of the decrease of Eu^2＋ PDOS when SiN concentration was lower than 0.25, therefore the absorption and luminescence intensity of BAM：Eu^2＋ were enhanced. Mulliken population of Si-N bond was higher than A1-O bond, while that of Eu-N bond was higher than Eu-O bond as well, indicating that Si-N bonds and Eu-N bonds possessed higher covalence than Al-O bonds and Eu-N bonds respectively. The existence of Si-N bonds and Eu-N bonds enhanced the local covalence of Eu^2＋, hence the optical stability of BAM：Eu^2＋.
文摘Objective To investigate the proteolytic mechanism of amyloid precursor protein （APP） and to explore amyloidbeta （Aβ） generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The four fragments, CFP, 54bp, YFP and C99 were ligated into pcDNA3.0 vector to construct the recombinant plasmids pcDNA3.0-CFP-54bp- YFP and pcDNA3.0-CFP-54bp-YFP-C99. The SH-SY5Y cells were transiently transfected with pcDNA3.0-CFP-54bp-YFP or pcDNA3.0-CFP-54bp-YFP-C99. The expression of fusion gene was examined under a multiphoton laser scanning microscope. Fluorescence resonance energy transfer （FRET） was used to measure the β cleavage and γ cleavage of APE Aβ generation was confirmed by immunocytochemistry and multiphoton laser scanning microscopy. Cell viability was tested by MTT assay at different time points. Results （1） The double restriction endonuclease digestion and sequencing analysis confirmed the authenticity of the recombinant plasmids pcDNA3.0-CFP-54bp-YFP and pcDNA3.0-CFP-54bp- YFP-C99. （2） Blue and yellow fluorescences were detected in the transfected cells. （3） FRET occurred in pcDNA3.0-CFP- 54bp-YFP-transfected cells but not in pcDNA3.0-CFP-54bp-YFP-C99-transfected cells. （4） Aβ was produced in the pcDNA3.0- CFP-54bp-YFP-C99 transfected cells. （5） Aβ-deposition was widespread in the cell. （6） Cell viability decreased along with the intracellular Aβ deposition. Conclusion C99 is important for the APP β cleavage. Aβ may be generated and deposited in cells at the early stage of Alzheimer＇s disease. Intracellular Aβ accumulation brings deleterious effects on cells.
文摘CaCO3 was chosen as main raw material and Solid State method was used to prepare the sample. The precursor was directly sintered at 1100 ℃ with reducing atmosphere for 3 h to obtain new green CaO：Tb^3＋, Li^＋ Phosphors. The effects of the content of the doping ions Tb^3＋ on the luminescent properties have been studied. The structure, morphology and luminescent properties of the phosphors were characterized by XRD, SEM, UV and PL-PLE spectra respectively. The results showed that the CaO：Tb^3＋, Li^＋ was a single face-centered cubic crystals, the phosphor particle distributed uniformly. The phosphor has a strong absorptive capacity excited by 282 nm ultraviolet ray, and could emit the strong green light with the wavelength of 543 nm （^5D4→^7F5）. The CaO：Tb^3＋, Li^＋ is a new type of green fluorescent material.
基金supported by the Tianjin Natural Science Foundation(No.06YFJZJC00300)the Natural Science Foundation of China(Nos.10674075,10774077,10674074,50802044 and 60736039)
文摘The simple approach to acquire the fltaxescenee spectra of vitamin bl, b2 and t6 is proposed by direct ilhanination on solid powder sample. The experimentally acquired fluorescence spectra are in accordance with the previous measurements on soluble samples. The fluorescence spectra for a mixture of vitamins bl, b2 and b6 with different concentrations have been investigated, and the fluorescence mechanism is explained on the basis of moleoalar struchture Possible reasons of the blue-shift of the fluorescence peak and enhancement of the peak power are explained as well. The advantages of solid powder method is analyzed and discussed.
文摘The extraction of Eu^(3+)from chloride medium using bifunctional ionic liquid extractants(Bif-ILEs)tri-n-octylmethyl ammonium bis(2-ethyl hexyl)phosphate([A336][D2EHP])and trihexyltetradecyl phosphonium bis(2-ethylhexyl)phosphate([P_(66614)][D2EHP])in kerosene was studied to develop environmentally friendly extraction process.The extraction behavior of Eu^(3+)was examined by varying key process parameters.The extraction behavior indicates that ammonium-based ionic liquid[A336][D2EHP]shows better extraction efficiency of Eu^(3+)than that of phosphonium-based ionic liquid[P_(66614)][D2EHP].Quantitative extraction of Eu^(3+)is obtained with 0.05 mol/L[A336][D2EHP],whereas,0.1 mol/L of[P_(66614)][D2EHP]is required to achieve the same extraction rate of Eu^(3+).The extraction process is endothermic with respect to[A336][D2EHP].Stripping experiments indicate that 100%of Eu^(3+)can be back extracted from both the loaded ionic liquids using 20 vol.%HNO_(3).The highest separation factor(βY/Eu)of 653.59 is reported at pH of 3.2,and the separation factor of Eu^(3+)over La^(3+)is 30.6 at the same pH.From the leach liquors of waste tube light powder,99.98%of Eu and 99.99%Y are recovered using 0.2 mol/L[A336][D2EHP]in 2-stage cross current extraction with aqueous to organcic ratio(O/A)of 1:1 and 1:2.
基金Project(200805330032)supported by the Natural Educative Doctoral Foundation of ChinaProjects(20080440987,200902475)supported by the China Postdoctoral Science Foundation
文摘Phosphor yttrium aluminum garnet Y3A15O12 （YAG）, activated with trivalent cerium （Ce^3＋）, was synthesized by T-tube impinging streams, T-type vortex impinging streams co-precipitation method （IS-CP） and direct co-precipitation method （D-CP）, respectively. The crystallization, morphologies, particle size and particle size distribution of the phosphors obtained under different experimental conditions were studied. The influence of various factors on the luminescence intensity of the phosphor was also investigated, such as feeding methods, volume flow rate, contents of Ce and initial reactant concentration. The results show that the precursors synthesized by T-tube impinging streams co-precipitation reaction transform to Y3A15O12 （YAG） phosphor at about 1 000 ℃. The particles are far smaller and narrower than those prepared by D-CP. In the impinging streams co-precipitation system, the luminescent intensity of YAG：Ce phosphor increases with the increase of liquid flow rate. The intensity firstly increases then decreases with the increasing Ce^3＋ doping content, and the maximum intensity is shown at 1.67% （molar fraction） Ce. Luminescent intensity gradually decreases with the increase of initial concentration of reactants. At the same operational condition, the luminescent intensity of the phosphors prepared by T-tube impinging streams reactor is higher than that by D-CP, and the luminescent intensity of the phosphors prepared by T-type vortex impinging streams is higher than that by T-tube impinging streams reactor.
文摘A highly intense green-emitting phosphor of Eu2＋-doped Sr4Al14O25 （SAE：Eu2＋） was synthesized by a solid state reaction. In this study, XRD, PL/PLE, QE, thermal stability and LED package tests are systematically carried out and investigated. The optimized-composition of （Sro 92Eu0.08）4Al14025 exhibited a green emission peak at 497 nm under excitation wavelength of 400 nm, giving the chromaticity coordinates of （0.14, 0.35） with excellent quantum efficiency （98%） compared to those of other green-commodities, such as Ba2SiO4：Eu2＋ （90%） and BaMgAl10O17：EU2＋, Mn2＋ （92%）. The results demonstrated that SAE：Eu2＋ could be a potential candidate as the NUV-pumping phosphor for applications in light-emitting diodes （LEDs）.
基金Project(200501) supported by the "985" Program of China
文摘Magnetic starch particles （MSPs） were synthesized in water-in-oil mieroemulsion at room temperature. MSPs were characterized by transmission electron microscopy （TEM）, Fourier transform infrared spectrometry （FTIR）, zeta potential system, thermogravimetric analysis （TGA） and vibrating sample magnetometry （VSM）. The average diameter of the MSPs was 220 nm, dispersed with well-proportioned size and magnetic resonance, the saturation magnetization was 3.64 A.mR/kg. MSP was coated with poly-L-lysine （PLL）, and then the surface of PLL-MSP was combined with fluorescein isothiocynate （FITC）. Results show that fluorescent/magnetic starch particles （FMSPs） are of stable photo-bleaching capability compared with free FITC, with low bio-toxicity and certain function of magnetic separation. It is expected that FMSPs are bifimctional nano-materials including fluorescence labelling and magnetic separation.
基金Supported by the National Natural Science Foundation of China （20676071, 20836004）.
文摘In order to study the effects of ionic surfactants on bacterial luciferase,the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison with bacterial luciferase,α-amylase was used since these two enzymes have similar electrostatic potential and charged active sites.After the enzymes were treated with the surfactants,the catalytic properties of bacterial luciferase andα-amylase were assayed,and fluorescence spectroscopy and circular dichroism (CD) were used to analyze the alteration of the protein structure.The results showed that when the DTAB concentration was low,the cationic surfactant DTAB enhanced the enzymatic activities of bacterial luciferase andα-amylase.On the other hand,the anionic surfactant SDS did not alter the enzymatic activity.The main interaction of cationic surfactant DTAB and the negatively charged surface of the proteins was the ionic interaction,which could alter the environment for the enzyme to work when the DTAB/enzyme molar ratio was low.However,at high cationic surfactant concentration,the ionic interaction and hydrophobic interaction might destroy the secondary and tertiary structures of the proteins,leading to the loss of enzymatic activities.
文摘A green-emitting phosphor Ca（Tb1-xLax）4（SiO4）3O （CTLS） was synthesized by a solid state reaction. X-ray diffraction, photoluminescence （PL） spectroscopy, reflectance spectra and chromaticity coordinates were carried out in this study. The CaTb4（SiO4）3O host has been known to crystallize in a hexagonal structure with disordering found in the Ca2＋ and Tb3＋ cation sites. The phosphors exhibited highly green-emitting band centered at 541 nm under ultraviolet excitation, which corresponds to the 5D4→7F5 transition. The optimal doping concentration of Tb3＋ was observed to be at 20 mol%, and the PL intensity was found to decline dramatically when the content of Tb3＋ exceeds 20m01% due to concentration quenching. Based on the results, we are currently evaluating the potential application of Ca（Tb,La）4（SiO4）30 as a new green-emitting near-UV LED convertible phosphor.
