The concentration quenching characteristics of 5D3-7FJ and 5D4-7FJ (J=0―6) transitions of Tb3+ in YBO3:Tb3+ phosphor

The photoluminescence quenching behaviors of ^5D3-^7Fj and ^5D4-^7Fj （J = 0—6） transitions of Tb^3＋ in YBO3：Tb under 130—290 nm excitation were systematically investigated. The results revealed that the quenching concentrations of both ^5D3-^7Fj and ^5D4-^7Fj transitions of Tb^3＋ in YBO3：Tb were mainly dependent on excitation wavelength. Particularly, the quenching concentrations of ^5D4-^7Fj transitions of Tb^3＋ under 130—290 nm excitation were correlated with excitation bands of YBO3：Tb. The quenching concentrations of ^5D3-^7Fj transitions remained at low concentration （2%） under 186—290 nm excitation and then increased gradually with energy of incoming excitation photon when excited at 130—186 nm. This dependence should be involved in their excitation mechanisms and quenching pathway in particular excitation region.[第一段]     

The luminescence properties of Sr3Gd(BO3)3: Tb3+ phosphors under vacuum ultraviolet excitation

Tb3+-activated Sr3Gd(BO3)3 green phosphors were prepared by conventional solid-state reaction. The vacuum ultraviolet (VUV) excitation, photoluminescence (PL) and decay properties of the phosphors in the visible range were investigated. The excitation spectrum showed a strong broad band from 160 to 200 nm with a maximum at 183 nm which was adjacent to the VUV excitation light source of 172 nm. Under excitation at 172 nm, the optimum co-doping concentration of Tb3+ was 10 mol%, and the emission intensity of Sr3Gd0.9(BO3)3:0.1Tb3+ was comparable to that of commercial Zn2SiO4:Mn2+. The strongest emission peak of Sr3Gd0.9(BO3)3:0.1Tb3+ was at 543 nm with chromaticity coordinates of (0.2626, 0.4922) and a lifetime of 2.32 ms. The optical properties of the green phosphor Sr3Gd(BO3)3:Tb3+ make it suitable for use in Hg-free fluorescent lamps and plasma display panels.     

Photoluminescence and cathodoluminescence properties of a novel CaLaGa307：Dy3＋ phosphor

A single host white emitting phosphor, CaLaGa3O7:Dy3+, was synthesized by chemical co-precipitation. Field emission scanning electron microscopy, X-ray diffraction, laser particle size analysis, and photoluminescence and cathodoluminescence spectra were used to investigate the structural and optical properties of the phosphor. The phosphor particles were composed of microspheres with a slight tendency to agglomerate, and an average diameter was of about 1.0 μm. The Dy3+ ions acted as luminescent centers, and substituted La3+ ions in the single crystal lattice of CaLaGa3O7 where they were located in Cs sites. Under excitation with ultraviolet light and a low voltage electron beam, the CaLaGa3O7:Dy3+ phosphor exhibited the characteristic emission of Dy3+ (4F9/2-6H15/2 and 4F9/2-6H13/2 transitions) with intense yellow emission at about 573 nm. The chromaticity coordinates for the phosphor were in the white region. The relevant luminescence mechanisms of the phosphor are investigated. This phosphor may be applied in both field emission displays and white light-emitting diodes.     

Kinetics of blue-green light-induced state transition and fluorescence quenching in the wild-type cyanobacterium Synechocystis PCC 6803 and apcD − and apcF − mutants

State transition and blue-green light-induced fluorescence quenching are two short-term processes in cyanobacteria. The details of their kinetics and the relationship between these processes have not been elucidated. In this work, these two processes were studied in the wildtype cyanobacterium Synechocystis PCC 6803 cells as well as in apcD^- and apcF^- mutants by monitoring their time- dependent 77 K fluorescence responses to blue-green light （430-540 nm） at a series of intensities ranging from 20-800 μE m^-2 s^-1. The lowest light intensity to induce fluorescence quenching in wild-type cells was 160 μE m^-2 s^-1 under the selected experimental conditions, while state transition took place at the intensities lower than 160 μE m^-2 s^-1 at a conservative level, but at variable rates. The quenching level increased at intensities higher than 160 μE m^-2 s^-1, reaching the maximum level at intensities equal to or higher than 200 μEm^-2 s^-1. Fluorescence kinetics indicated that both the length of the induction period and time required to reach the maximum level were functions of light intensity. State transitions as well as fluorescence quenching took place in both wildtype and mutant cells, but might involve different mechanisms.     

Microstructure investigation and multicolor upconversion in Yb~(3+)/Ln~(3+)(Ln=Er/Tm/Ho) ions doped α-Sialon

Yb~(3+)/Ln~(3+)(Ln=Er/Tm/Ho)-α-sialon ceramics were fabricated by hot press sintering technique.Their microstructure and luminescent properties were studied by XRD,EDS,HRTEM and photoluminescence measurements.The results showed that the sintered ceramics consisted ofα-Sialon with a trace amount ofβ-Sialon phase.The frequency upconversion and downconversion properties of Yb~(3+)/Ln~(3+)(Ln=Er/Tm/Ho)-α-Sialon ceramics were investigated under 980 nm low-power excitation.The different concentrations of Yb~(3+)/Ln~(3+)(Ln=Er/Tm/Ho)produced multicolor emissions characteristics of each Ln~(3+)ion as a result of the energy transfer from Yb~(3+)to Er~(3+),Tm~(3+)and Ho~(3+)ions.The EDS spectra measurements and mappings showed that the Ln~(3+)ions were well incorporated in theα-Sialon matrix.Temporal evolution of the emission decay behavior has been investigated to understand the energy transfer mechanism.     

Near-infrared to visible up-conversion emissions of Er^3＋ doped Al2O3 powders derived from the sol-gel method

The Er3 doped Al2O3 powders were prepared by the sol-gel method using the aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with addition of the erbium nitrate [Er(NO3)3.5H2O]. The different phase structure, including three crystalline types of (Al,Er)2O3 phases, γ, θ, α, and two Er-Al-O phases, ErAlO3 and Al10Er6O24, was obtained with the 1 mol% Er3 doped Al2O3 powders at the different sintering temperatures of 600―1200℃. The green and red up-conversion emissions centered at about 523, 545 and 660 nm, corresponding respectively to the 2H11/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3 , were detected by a 978 nm semiconductor laser diodes excitation. The phase structure and OH content had evident influence on the up-conversion emissions intensity. The maximum intensities of both the green and red emissions were obtained respectively for the Er3 doped Al2O3 powders sintered at 1200 ℃, which was composed mainly of α-(Al,Er)2O3, less of ErAlO3 and Al10Er6O24 phases, and with the least OH content. The two-photon absorption up-conversion process was involved in the green and red up-conversion emissions of the Er3 doped Al2O3 powders.     

Effects of Yb～(3 ) codoping on visible and near infrared emissions of Er～(3 )-Yb～(3 ) codoped Al_2O_3 powders by the sol-gel method

The 0.1 mol% Er3 and 0―2 mol% Yb3 codoped Al2O3 powders were prepared by the sol-gel method,and the phase structure,including only two crystalline types of doped Al2O3 phase,γ-(Al,Er,Yb)2O3 and θ-(Al,Er,Yb)2O3,was detected at the sintering temperature of 1000℃. The visible and near infrared emissions properties depended strongly on the Yb3 codoping,and the corresponding maximal peak intensities centered at about 523,545,660 and 1533 nm were obtained respectively for the 0.1 mol% Er3 and 0.5 mol% Yb3 codoped Al2O3 powders,which were composed of θ-(Al,Er,Yb)2O3 and a small amount of γ-(Al,Er,Yb)2O3 phases. The two-photon absorption process was responsible for the visible up-conversion emissions,and the one-photon absorption process was involved in the near infrared emissions of the Er3 -Yb3 codoped Al2O3 powders.     

Kinetics of blue-green light-induced state transition and fluorescence quenching in the wild-type cyanobacterium Synechocystis PCC 6803 and apc D2 and apc F2 mutants

State transition and blue-green light-induced fluorescence quenching are two short-term processes in cyanobacteria. The details of their kinetics and the relationship between these processes have not been elucidated.In this work, these two processes were studied in the wildtype cyanobacterium Synechocystis PCC 6803 cells as well as in apc D-and apc F-mutants by monitoring their timedependent 77 K fluorescence responses to blue-green light(430–540 nm) at a series of intensities ranging from20–800 l E m-2s-1. The lowest light intensity to induce fluorescence quenching in wild-type cells was160 l E m-2s-1under the selected experimental conditions, while state transition took place at the intensities lower than 160 l E m-2s-1at a conservative level, but at variable rates. The quenching level increased at intensities higher than 160 l E m-2s-1, reaching the maximum level at intensities equal to or higher than 200 l E m-2s-1.Fluorescence kinetics indicated that both the length of the induction period and time required to reach the maximum level were functions of light intensity. State transitions as well as fluorescence quenching took place in both wildtype and mutant cells, but might involve different mechanisms.     

Preparation and luminescence characteristics of Sr3SiO5：Eu^2＋ phosphor for white LED

The Sr3SiO5：Eu^2＋ phosphor was synthesized by high temperature solid-state reaction. The emission spectrum of Sr3SiO5：Eu^2＋ shows two bands centered at 487 and 575 nm, which well agree with the theoretic values of emission spectrum. The excitation spectrum for 575 nm emission center has several excitation bands at 365, 418, 458 and 473 nm. And the results show that the emission spectrum of Sr3SiO5：Eu^2＋ is influenced by the Eu^2＋ concentration. The relative emission spectra of the white-emitting InGaN-based YAG：Ce^3＋ LED and Sr3SiO5：Eu^2＋ LED were investigated. The results show that the color development of InGaN-based Sr3SiO5：Eu^2＋ is better than that of InGaN-based YAG：Ce^3＋, and the CIE chromaticity of InGaN-based Sr3SiO5：Eu^2＋ is （x=0.348, y=0.326）.     

Carbazole—containing light—emitting polymers：Properties of excited states

A series of light-emitting conjugated polymers alternatively involving carbazole and bivinylene arylene moieties in the main chain were synthesized via Wit-tig-Horner type copolymerization.The photoinduced charge transfer process relating to these polymers was investigated by using the technique of fluorescence spectroscopy.The interaction between excited copolymers and C60 in benzene solution was studied.The fluorescence quenching can be well described by the “sphere-of-action” mechanism.It is be-lieved that two basic steps are involved in the quenching process,i.e. the diffusion of excitation within the comjugated polymers and the dissociation of the exctions trapped by fullerene,The radius of the sphere-of-action can be related to the excitation diffusion length,which depends on the lifetime of the exciton.The dynamic fluorescence quenching of the copolymers by another quencher,1,4-dicyanobenzene(DCB) was also surveyed.Copolymers with different chain confor-mations show different temperature effects in the dynamic quenching.A planar conformation is beneficial for the quenching via bimolecular collision.     

A kinetic study of the reaction of ozone with ethylene in a smog chamber under atmospheric conditions

Ozone is one of the key species in the processes of atmospheric chemistry, which can be taken as an indicator of oxidation capacity in the troposphere. The reaction of ozone with reactive gases is an important process in the troposphere. Experimental simulation equipment of smog chamber for atmospheric reactions is used to study the reaction of ozone with ethylene in real atmospheric environment with ozone concentrations of 100―200 ppb. The concentrations of ozone and ethylene were moni-tored during the reaction with the combination of Model 49C-O_3 Analyzer and GC-FID. A rate constant of 1.01×10~(-18) (cm~3·mol~(-1)·s-(~1)) was obtained at 286.5 K, under condition of which the half-life of ozone was 88 min. The results obtained from our experiments are in excellent agreement with those reported previously by other researchers under extremely low pressure in terms of matrixisolation technology. This demonstrates that our equipment of smog chamber for atmospheric reactions is reliable, which can be used for further research of the processes of atmospheric reactions.     

Effects of synthetic conditions on the structure and morphology of open-ended vanadium oxide nanotubes and study of their growth mechanism

Vanadium oxide nanotubes (VOx-NTs) have been synthesized by using n-butylamine as structuredirecting template and V2O5 as precursor under hydrothermal conditions. XRD, FTIR, SEM, TEM, BET and TG-DTA characterizations have been performed to both optimize the synthetic conditions and understand the growth mechanism of VOx-NTs. The results showed that open-ended VOx-NTs were obtained under the optimized conditions (hydrothermal temperature: 150―160°C, hydrothermal time: 5―7 d, the molar ratio of V2O5 to n-butylamine is 1:1) with diameters ranging from about 30 to 100 nm and several micrometers in length. The BET surface area and the desorption cumulative pore volume of pores of the as-synthesized sample were about 27.4609 m2/g and 0.191087 cm3/g, respectively. The result presents that the synthesis of VOx-NTs is controlled by the "rolling" mechanism and temperature is primary driving force for rolling.     

Pollutants in stormwater runoff in Shanghai （China）： Implications for management of urban runoff pollution

Runoff samples were collected from four functional areas (traffic, residential, commercial and industrial) and four roof types (old concrete,new concrete, old clay and new clay) in central Shanghai, China, during rain events. The event mean concentrations (EMCs) of three forms of nitrogen (NH4+―N,NO3-―N,NO2-―N) and the temporal variations of total phosphorus (TP) were then measured to evaluate the effects of runoff from different areas on water quality management. The results revealed that the TP levels varied significantly in the samples collected from different functional areas and roof types during rain events. In addition, although the NO3-―N and NO2-―N concentrations in runoff remained well below the fifth class values of the national surface water quality standards, the NH4+―N levels were 1.36, 1.17, 1.10 and 0.85 times higher than the standard value in samples collected from commercial, traffic, industrial,and residential areas, respectively. Similarly, the concentrations of NH4+―N in samples collected from old concrete, new concrete,old clay and new clay roofs exceeded the fifth class standard by 6.66, 5.72, 4.32 and 3.32 times, respectively. And the NO3-―N levels were 1.86 and 1.53 times higher than the standard values in runoff samples collected from new and old concrete roofs, respectively.     

Synthesis and properties of a Pr（Ⅲ） complex with 2-acetylbenzimidazoledehyde-glycine Schiff-base ligand

Abstract The 2-acetyl-benzimidazoledehyde-glycine Schiff-base ligand and the corresponding Pr（Ⅲ） complex Pr2L3（NO3）3· 2CH3OH （L=C11H10N3O2） were synthesized in methanol and characterized by a series of methods, including chemical analysis, elemental analysis, TOF-MS, ^1H NMR, UV-, IR-, Raman spectra, thermal analysis, and the three-dimension fluorescence excitation and emission spectra. The Pr（Ⅲ） complex exhibits extraordinary water-solubility and the Pr（Ⅲ） hydroxide appears at pH≥13. The complex also possesses specific fluorescent properties. Thus, at the excitation wavelengths 200.0-280.0 and 260-350 nm the fluorescence bands were observed at 290.0 and 400.0 nm, respectively.     

Novel trichromatic phosphor Co-doped with Eu, Tb in SiO2 gel matrix

The Eu, Tb co-doped SiO2 matrix tricolor fluorescence system was prepared by sol-gel technique. Red emission at 618 nm, green emission at 543 nm and blue emission at 350-500 nm were observed in the PL spectra of the sample, indicating that Eu^3＋, Eu^2＋ and Tb^3＋ ions coexisted in the matrix. In the co-doped sample, the blue emission of Eu^2＋ was much stronger than that of the sample single doped with Eu, which implied that the electron transfer between Eu^3＋ and Tb^3＋ maybe happened in the SiO2 matrix. The influences of the annealing temperature and Tb concentration on the PL spectra of the samples were investigated. The optimal doped concentration of Tb was determined to be 0.2% and the optimal annealing temperature 850℃. Annealed at 600℃, Tb^3＋ had a sensitizing effect on Eu^3＋ in the SiO2 matrix, and the emission intensity of Eu^3＋ in the Eu, Tb co-doped sample was more than four times that of the single doped sample, which could be attributed to the energy transfer from Tb^3＋ to Eu^3＋.     

Effects of Tx-100-SDS on crystal growth of calcium carbonate in reverse microemulsion solution

Syntheses of CaCO3 crystals in reverse microemulsion solutions containing 1-(1,1,3,3-tetramethylbu- tyl)-4-hydroxypolyethoxybenzene (Tx-100), sodium dodecyl sulfate (SDS) and their equimolar mixture were carried out at room temperature respectively. The crystal phase of CaCO3 is changed from calcite at low concentrations to vaterite at high concentrations of SDS and Tx-100. From rods at low concentration to olivary spheres at high concentration, SDS can influence the morphology of CaCO3 significantly, while almost no such effect for Tx-100. Hollow spheres, olivary spheres and even two fused olivary spheres of CaCO3 were produced at different concentrations of Tx-100-SDS, and the variation of crystal phase is opposite to that in the presence of SDS or Tx-100 alone. The effects of interaction of SDS with Tx-100 on morphology and crystal phase of CaCO3 were discussed. It was estimated to put forward that the formation of hollow CaCO3 crystals was caused by the collaborating actions of SDS template and TX-100 inhibition.     

Effects of lanthanum and gadolinium on proliferation and differentiation of primary osteoblasts

The effects of La3 and Gd3 on the proliferation, differentiation and adipogenic transdifferentiation of rat calvarial osteoblast-like cells (ROB cells) were evaluated by MTT method, measuring the activity of alkaline phosphatase (ALP) and Oil red O measurement. Both of La3 and Gd3 inhibited the proliferation of ROB cells at all concentrations (1×10-5, 1×10-6, 1×10-7, 1×10-8, 1×10-9 mol·L-1). La3 at concentration of 1×10-5mol·L-1 significantly increased the alkaline phosphatase activity of ROB cells up to 3 folds (P<0.01). However, the effects reversed to inhibit at other concentrations. Gd played a negative role in the alkaline phosphatase activity. La3 inhibited the adipogenic transdifferentiation of ROB cells at all concentrations in a dose-dependent way. However, Gd promoted the adipogenic transdifferentiation of ROB cells at 1×10 and 1×10 mol·L . These findings suggested that the effects of rare earth elements on the proliferation, differentiation and adipogenic transdifferentiation of ROB cells were dependent on their concentrations and species.     

The first determination of atmospheric phosphine in Antarctica

It is generally thought that phosphine (PH3) concentrations exist at the low ng/m3 level during the night and at the pg/m3 level during daylight in the remote atmosphere of the lower troposphere. The first de- termination of gaseous PH3 on the Antarctic Millor Peninsula is reported in this paper. No PH3 was de- tected in the air samples around 10:00 when it was sunny. However, PH3 was found in all the 10:00 air samples when it was cloudy or light snow with the average of 75.3±28.8 ng/m3 (n=5). It was also found in nearly all the samples around 22:00 with the average of 87.2±70.9 ng/m3 (n=11). Atmospheric PH3 concentrations around 22:00 were generally higher than those around 10:00 in January and they were almost the same in February. In addition, PH3 concentrations around 22:00 showed a downtrend with the decreasing air temperature, suggesting that light intensity and air temperature had an important effect on atmospheric PH3 concentration. It is very surprising to have found that high concentrations of PH3 exist in the Antarctic atmosphere under the influence of strong UV-radiation and light intensity. The tentative analyses show that dry, cold and very clean atmosphere may be very suitable for the PH3 sur- vival and cause the concentration to increase and accumulate in the local atmosphere. New ap- proaches for the PH3 formation and the process of atmospheric chemistry may exist under such an extreme environment. Atmospheric PH3 may also be from the emissions of local sources.     

Evolution of ferronickel particles during the reduction of low-grade saprolitic laterite nickel ore by coal in the temperature range of 900–1250℃ with the addition of CaO–CaF_2–H_3BO_3

The method of producing ferronickel at low temperature(1250–1400℃) has been applied since the 1950s at Nippon Yakin Kogyo,Oheyama Works, Japan.Limestone was used as an additive to adjust the slag composition for lowering the slag melting point.The ferronickel product was recovered by means of a magnetic separator from semi-molten slag and metal after water quenching.To increase the efficiency of magnetic separation, a large particle size of ferronickel is desired.Therefore, in this study, the influences of CaO, CaF_2, and H_3BO_3 additives on the evolution of ferronickel particle at ≤1250℃ were investigated.The experiments were conducted at 900–1250℃ with the addition of CaO,CaF_2, and H_3BO_3.The reduction processes were carried out in a horizontal tube furnace for 2 h under argon atmosphere.At 1250℃, with the CaO addition of 10 wt% of the ore weight, ferronickel particles with size of 20 μm were obtained.The ferronickel particle size increased to 165μm by adding 10 wt% CaO and 10 wt% CaF_2.The addition of boric acid further increased the ferronickel particle size to 376 μm, as shown by the experiments with the addition of 10 wt% CaO, 10 wt% CaF_2, and 10 wt% H_3BO_3.     

Estimation of soil respiration in a paddy ecosystem in the subtropical region of China

Water vapor, energy exchange, and CO2 flux were measured continuously from 2003 to 2005 using the eddy covariance technique in a paddy ecosystem in the subtropical region of China. The CO2 fluxes at nighttime during fallow periods (from middle October to late April) were used to analyze the dynamics of soil respiration and its relationship with soil temperature, and to simulate the annual dynamics of soil respiration in paddy ecosystems. The variation of soil respiration showed a clear seasonal pattern. The soil respiration rates at night during the fallow periods were 52―398 mg·m-2·h-1, and exponen- tially correlated (P<0.001) with soil temperatures at different depths of soil (5, 10, and 20 cm), particularly the temperature measured at a depth of 5 cm. Based on the simulated exponential equations developed, annual average soil respiration rates and total soil respiration of paddy soil in the subtropical region of China were estimated to be 178.5―259.9 mg·m-2·h-1 and 1.56―2.28 kg·m-2·a-1, respectively. The simulation equations can be applied to evaluating soil respiration in paddy ecosystems during the rice-growing season.