掺杂罗丹明6G染料的氟磷酸盐玻璃的制备工艺优化及其激光性质

系统地研究了Sn -Pb -P -O -F系统氟磷酸盐光学玻璃的制备工艺过程 ,对玻璃原料、坩埚选择、保护气氛、熔制过程的温度制度和时间制度等关键工艺进行了优化研究 .确定了在优化的工艺下 ,具有较佳化学稳定性能和光学透过性能的、适合于罗丹明 6G染料进行掺杂的基质玻璃 :2 0SnO -50SnF2 -3 0P2 O5-5PbO .探明了在该低熔玻璃中进行染料掺杂的工艺方法与合适的温度条件 .表征了这种掺杂玻璃的光学与发光性质 .首次成功地在Nd :YAG激光器的二次谐波 ( 53 2nm)泵浦下获得了波长覆盖范围宽达 60 .2nm、中心波长为 582 .8nm的激光输出 .

Effect of Surface-Covered Annealing on the Optical Properties of ZnO Films Grown by MOCVD

ZnO films grown by metal organic chemical vapor deposition at atmospheric pressure are annealed at 850℃ ,with the film surfaces exposed to air or covered by a sapphire wafer. The optical properties of the as-grown and the annealed samples are studied by photoluminescence （PL） spectroscopy. It is found that the air-exposure annealing effectively removes the hydrogen impurities from the ZnO films but greatly increases the deep-level emission. In the surface-covered annealed sample, an elimination of the hydrogen impurities is also observed, and the deep-level emission disappears completely. The free exciton emission is significantly enhanced in the ZnO film after surface-covered annealing.

Purification and Characterization of Flammulin,a Basic Protein with Anti-tumor Activities from Flammulina velutipes

Aim To purify and characterize flammulin, a basic protein with anti-tumoractivities. Methods Ammonium sulfate, ethanol fractionation and column chromatography were used forseparation and purification. Electrophoretic analysis, amino acid analysis, and MS of flammulin werecarried out. Results Flammulin was purified to electrophoretic homogeneity and crystallized. With amolecular mass of 19891.13 Da, pI 8.9, λ_(max) = 276 - 278 nm, λ_(min) = 250 nm, flammulin wascharacterized by its lack of methionine. Fingerprint mapping of flammulin was determined by MALDI-MSfollowing in-gel protease digestion; no close matches were identified. Conclusion Flammulin waspurified to electrophoretic homogeneity, and its characteristics are discussed for the first time.

Experimental study on mechanism of influence of laser energy density on surface quality of Ti-6Al-4V alloy in selective laser melting

This experiment obtained different laser energy density(LED) by changing SLM molding process parameters.The surface morphology, surface quality, and microstructure of as-fabricated samples were studied. The effects of scanning speed, hatching space, and laser power on surface quality were analyzed, and the optimal LED range for surface quality was determined. The results show that pores and spherical particles appear on the sample’s surface when low LED is applied, while there are lamellar structures on the sides of the samples. Cracks appear on the sample’s surface,and the splash phenomenon increases when a high LED is taken. At the same time, a large amount of unmelted powder adhered to the side of the sample. The surface quality is the best when the LED is 150-170 J/mm^(3). The preferred hatch space is currently 0.05-0.09 mm, the laser power is 200-350 W, and the average surface roughness value is(15.1±3) μm.The average surface hardness reaches HV404±HV3, higher than the forging standard range of HV340-HV395.Increasing the LED within the experiment range can increase the surface hardness, yet an excessively high LED will not further increase the surface hardness. The microstructure is composed of needle-like α’-phases with a length of about 20μm, in a crisscross ‘N’ shape, when the LED is low. The β-phase grain boundary is not obvious, and the secondaryphase volume fraction is high;when the LED is high, the α’-phase of the microstructure is in the form of coarse slats, and the secondary-phase is composed of a small amount of secondary α’-phase, the tertiary α’-phase and the fourth α’-phase disappear, and the volume fraction of the secondary-phase becomes low.

Laser-induced breakdown spectroscopy characterization of Al in different matrix

Some experimental investigations were carried out with the samples of metal Al and AlCl3 solutions. It is found that the spectrum varies with the change of experimental setup parameters both in Al bulk material and AlCl3 solutions. The temporal evolution properties and the affection of incident laser energy on the laser-induced breakdown spectroscopy (LIBS) signals were also discussed. The lifetime of laser induced plasma in AlCl3 solutions is found to be about 30 ns which is much shorter than in solid materials. Compared with the solid samples, the Al LIBS signals in AlCl3 solutions require higher laser energy. Under the optimized conditions, the detection limit of Al in AlCl3 solution was determined to be around 1000 ppm for the system we used.

Diffraction Properties of Blazed Gratings Illuminated with Broad-bandwidth and Divergent Beam

Far-field intensity and diffraction efficiency of the blazed reflection gratings illuminated with broad-bandwidth and divergent beam are investigated.When the spectral width and divergence of the incident beam with a constant energy increase,the maximum intensity decreases,and the half width at e-2 of the maximum intensity becomes wider.Diffraction efficiency has no deterioration for the blazed grating with a proper groove shape even when the incident light contains a broad range of wavelengths and comes from a wide range of angles.

Study on the composite Nd:YAG crystal by laser micro-Raman spectroscopy

The composite Nd：YAG crystal with undoped YAG end caps was fabricated by thermal bonding technique. Scanning electron microscopy （SEM） result shows that the width of the bonded interface was about 0.5 lain. The laser micro-Raman was used to study the bonded interface of the composite crystal. The results of Raman spectra and the bonded interface image indicate that the undoped YAG and Nd：YAG crystals have been well bonded together. Furthermore, it can be drawn that the structure and the composition of the bonded interface are the same as the undoped YAG crystal, and that the Nd^3＋ ions do not enter the bonded interface and the YAG side. This property is advantageous to decrease the thermal effect of the boned interface and to improve the laser stability.

Synthesis and spectroscopic properties of N^2, 3-ethenoguanosine

The synthetic route of N^2, 3-ethenoguanosine （ε-G） was described. Its ultraviolet and fluorescent properties at various pH were studied. These results indicate that ε-G dissociates a hydrogen ion to give the anion ε-G and associates a hydrogen ion to give a the cation ε-GH~. The neutral specie ε-G is the origin of fluorescence. The fluorescent properties in different media were studied and there was most strong fluorescence in water. Based on fluorescencc quenching of ε-G on BSA, the binding constant and the number of binding sites between ε-G and BSA were determined, which were 1.78x10^3 L/mol and I, respectively. The quenching mechanism was discussed. It indicates that the powerful interaction exists between ε-G and BSA.

Synthesis and photophysical and electrochemical properties of new cyclometalated platinum complex containing oxadiazole ligand

A new cyclometalated platinum complex containing 2, 5-bis(naphthalene-1-yl)-1,3,4-oxadiazole ligand was synthesized and characterized. The UV-Vis absorptions and photoluminescent properties of the ligand and its platinum complex were investigated. A characteristic metal-ligand charge transfer absorption peak at 439 nm in the UV spectrum and a strong emission peak at 625 nm in the photoluminescence spectrum were observed for this complex in dichloromethane. Cyclic voltammtry (CV) analysis shows that the EHOMO (energy level of the highest occupied molecular orbital) and ELUMO (energy level of the lowest unoccupied molecular orbital) of the platinum complex are about 、5.69 and 、3.25 eV, respectively, indicating that the oxadiazole-based platinum complex has a potential application in electrophosphorescent devices used as a red-emitting material.

Tannins from Canarium album with potent antioxidant activity

The contents of total phenolics and extractable condensed tannins in the leaves, twigs and stem bark of Canarium album were determined. The structural heterogeneity of condensed tannins from stem bark was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF MS） and nuclear magnetic resonance （NMR） analyses The results show the predominance of signals representative of procyanidins and prodelphinidins. In addition, epicatechin and epigallocatechin polymers with galloylated procyanidin or prodelphinidin were also observed. The tannins were screened for their potential antioxidant activities using l,l-diphenyl-2-picrylhydrazyl （DPPH） and ferric reducing/antioxidant power （FRAP） model systems. Tannins extracted from leaves, twigs and stem bark all showed a very good DPPH radical scavenging activity and ferric reducing power.

Nonlinear Propagation of Coupling Optical Pulse under Compton Scattering in Laser Medium

After considering Kerr nonlinear effect, group velocity dispersion of host and gain distribution of active particle in laser amplifying medium, a basic equation describing propagation of the coupling optical pulse under the multi-photon nonlinear Compton scattering in the laser amplifying medium has been deduced. Besides, the profile and power spectrum of a picosecond-level super-Gaussian coupling pulse in the laser amplifying medium have been discussed when its central frequency coincides with the gain peak frequency of the laser amplifying medium.

Effect of Ultrafine Particles on Flow Field and Transport Properties near the Interface Around a Moving Bubble

Laser Doppler Anemometer has been used to measure the flow field characteristics near the interface around a moving bubble in the presence of ultrafine particles. In order to model a moving bubble, the bubble was fixed into the counter flow liquid by a metal mesh. Experimental materials are air and water, and the particles are complex oxidate powder. Experiments were carried out under the operating conditions: the liquid flow velocity u 0 is 12.6 cm/s, the equivalent diameter d e is 0.6 cm, the mass concentration of particle is 0.2 0 0 ,the average particle diameter is about 10 nm and the density is 2 g/cm 3. The velocity profiles of both frontal and tail vortex areas were measured respectively. The experimental results show that the velocity fields are obviously changed in the existence of particles. In the frontal area of the bubble, both tangential and normal velocities decrease due to the presence of particles, but in tail vortex area, the tangential velocities increase remarkably, and normal velocities rise gradually from the center towards the fringe in the opposite tendency to that of no particles. The influences of flow field change in the presence of particles on gas liquid mass transfer are analyzed and discussed.

Properties of fluoride film and its effect on electroless nickel deposition on magnesium alloys

The physical characteristics and microstructure of the fluoride film formed during activation were investigated using SEM,XPS and SAM,and its stability in electroless nickel(EN) bath was analyzed.The effects of the fluoride film on EN deposition were studied additionally.The results show that the fluoride film on magnesium alloys is a kind of porous film composed of MgF2 with thickness of 1.6-3.2 μm.The composition of the activation bath and pretreatment of EN processing have influence on the composition of the fluoride film.The fluoride is stable and dissolves little in EN bath;as a result,the fluoride film can protect magnesium substrate from the corrosion of EN bath.The composition of fluoride determines the initial deposition of EN and part of the fluoride film finally exists as inclusion in EN coating.

Effects of Annealing Temperature on Properties of ZnO Thin Films Grown by Pulsed Laser Deposition

ZnO thin films are deposited on n-Si（111） substrates by pulsed laser deposition（PLD） system. Then the samples are annealed at different temperatures in air ambient and their properties are investigated particularly as a function of annealing temperature. The microstructure, morphology and optical properties of the as-grown ZnO films are studied by X-ray diffraetion（XRD）. atomic force mieroseope（AFM）, Fourier transform infrared spectroscopy（FTIR） and photoluminescence（PL） spectra. The results show that the as- grown ZnO films have a hexagonal wurtzite structure with a preferred c-axis orientation. Moreover, the diameters of the ZnO crystallites become larger and the crystal quality of the ZnO fihns is improved with the increase of annealing temperature.

Association between the Epidermal Growth Factor Gene and Intelligence in Major Depression Patients

Objective To study the association between the epidermal growth factor(EGF) gene and intelligence in patients with major depression.Methods Intelligence measurement using Wechsler Adult Intelligence Scale(WAIS) was perfor-med on 120 unrelated patients with major depression and 46 control subjects.Blood was collected from all subjects for extraction of genomic DNA.Four single nucleotide polymorphisms(SNPs) in the EGF gene were genotyped using polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF-MS).Results Mean scores of both score lang and score task,two subtests in WAIS,differed significantly between major depression patients and controls(P<0.0001).Quantitative trait analysis showed that the genetype of rs2250724 was closely associated with score lang and score task in major depression patients.The associations were still significant after 10 000 permutations.Conclusions Although preliminary,our results provide evidence for association between the EGF gene and intelligence in patients with major depression.Genetic variation in the EGF gene may increase the susceptibility of major depression.

Red phosphorescent organic light-emitting diodes based on a novel host material with thermally activated delayed fluorescent properties

High cost of phosphors and significant efficiency roll-off at high brightness are the two main factors that limit the wide application of phosphorescent organic light-emitting diodes （PHOLEDs）. Efforts have been paid to find ways to reduce the phosphors＇ concentration and efficiency roll-off of PHOLEDs. In this work, we reported red emission PHOLEDs with low dopant concentration and low efficiency roll-off based on a novel host material 2,4-biscyanophenyl-6-（12-phenylindole[2,3-a]carbazole-ll-yl）-1,3,5-triazine （BCPICT）, with thermally activated delayed fluorescent （TADF） properties. The device with 1.0% dopant concentration displayed a maximum external quantum efficiency of 10.7%. When the dopant concentration was increased to 2.0%, the device displayed a maximum external quantum efficiency of 10.5% and a low efficiency roll-off of 5.7% at 1000 cd/m^2.

Laser induced oxidation and optical properties of stoichiometric and non-stoichiometric Bi2Te3 nanoplates

Bi-Te nanoplates （NPs） grown by a low pressure vapor transport method have been studied by Raman spectroscopy, atomic force microscopy （AFM）, energy- dispersive X-ray spectroscopy （EDS）, and Auger electron spectroscopy （AES）. We find that the surface of relatively thick （more than tens of nanometers） Bi2Te3 NPs is oxidized in the air and forms a bump under heating with moderate laser power, as revealed by the emergence of Raman lines characteristic of Bi2O3 and TeO2 and characterization by AFM and EDS. Further increase of laser power burns holes on the surface of the NPs. Thin （thicknesses less than 20 nm） NPs with stoichiometry different from Bi2Te3 were also studied. Raman lines from non-stoichiometric NPs are different from those of stoichiometric ones and display characteristic changes with the increase of Bi concentration. Thin NPs with the same thickness but different stoichiometries show different color contrast compared to the substrate in the optical image. This indicates that the optical absorption coefficient in thin Bi-Te NPs strongly depends on their stoichiometry.

Influence of Mg Composition on Optical Properties of Exciton Confinement in Strained Wurtzite ZnO/Mg_x Zn_(1-x) O Cylindrical Quantum Dots

Based on the effective-mass approximation and variational approach, excitonic optical properties are investigated theoretically in strained wurtzite （WZ） ZnO/MgxZn1-xO cylindrical quantum dots （QDs） for four different Mg compositions： x = 0.08, 0.14, 0.25, and 0.33, with considering a three-dimensional carrier confinement in QDs and a strong built-in electric field effect due to the piezoelectricity and spontaneous polarization. The ground-state exciton binding energy, the interband emission wavelength, and the radiative lifetime as functions of the QD structural parameters （height and radius） are calculated in detail The computations are performed in the case of finite band offset. Numerical results elucidate that Mg composition has of ZnO/MgxZn1-x 0 QDs. The ground-state exciton a significant influence on the exciton states and optical properties binding energy increases with increasing Mg composition and the increment tendency is more prominent for small height QDs. As Mg composition increases, the interband emission wavelength has a blue-shift if the dot height L 〈 3.5 nm, but the interband emission wavelength has a red-shift when L 〉 3.5 nm. Furthermore, the radiative lifetime increases rapidly with increasing Mg composition if the dot height L 〉 3 nm and the increment tendency is more prominent for large height QDs. The physical reason has been analyzed in depth.

Synthesis,photophysical properties and TD-DFT calculation of four two-photon absorbing triphenylamine derivatives

In this study,linear absorption,single-photon excited fluorescence,fluorescence quantum yields,fluorescence lifetime and two-photon excited fluorescence of a series of triphenylamine derivatives (L1,L2,L3 and L4) have been measured.L1 and L3 are D--A type dyes,while L2 and L4 are D--D--A type dyes (D=donor,A=acceptor).The investigated compounds consist of triphenylamine-bearing donor-substituted and/or systematically extended-conjugated length,which are designed to gain insight into the effect of the ethoxyl unit and-linkage length on the linear and nonlinear optical properties.The influence of solvent polarity on the photophysical properties was investigated.Employing time-dependent density functional theory (TD-DFT) calculations,the structure-property relationships are discussed.

Laser-induced etching parameters impact on optical properties of the silicon nanostructures

Porous silicon (PS) was fabricated by laser-induced etching (LIE) process. The objective of this study is to investigate the selected LIE parameters to control size and shape of nanostructures,which are considered important factors in semiconductor device applications. Photoluminescence output intensity becomes stronger due to the increase in the number of emitted photons on the porous surface. There is a dramatic increase in photoluminescence intensity due to the increase of porosity as a function of laser power density. The increase in electrolyte concentration is an important parameter to accelerate the dissolution reaction on the interface layer between the electrolyte solution and wafer surface. PS spectra displayed a stronger Raman intensity than crystalline bulk Si;also the PS spectrum was shifted and broadened as a function of LIE parameters.