Ternary Ag/AgC l/BiO IO3 composite photocatalysts are prepared by a facile method. Enhanced visible-light absorption and charge carrier separation are achieved after the introduction of Ag/AgC l particles into BiO IO3...Ternary Ag/AgC l/BiO IO3 composite photocatalysts are prepared by a facile method. Enhanced visible-light absorption and charge carrier separation are achieved after the introduction of Ag/AgC l particles into BiO IO3 systems,as revealed by ultraviolet-visible diffuse-reflectance spectrometry,photocurrent response and electrochemical impedance spectroscopy. The Ag/AgC l/BiO IO3 composites are applied to the visible-light photocatalytic oxidization of NO in air and exhibit an enhanced activity for NO removal in comparison with Ag/AgC l and pure BiO IO3. A possible photocatalytic mechanism for Ag/AgC l/BiO IO3 is proposed,which is related to the surface plasmon resonance effects of Ag metal and the effective carrier separation ability of BiO IO3. This work provides insight into the design and preparation of BiO IO3-based materials with enhanced visible-light photocatalysis ability.展开更多
We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) ...We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) and unit transpiration rates (TRN) were both significantly decreased upon an osmotic shock caused by PEG 6000 solution (osmotic potential = -0.24 MPa) or a saline, which was applied by 50 mmol/L Na+-salts (NaNO3 : NaHCO3 : NaH2PO4 = 5 : 4 : 1, pH 6.8, osmotic potential = -0.24 MPa) or by 50 mmol/L Cl--salts (KCl : NH4Cl = 1:1, osmotic potential = -0.24 MPa). However, salt-treated P. euphratica plants maintained typically higher TRN than those exposed to PEG. Xylem ABA concentrations increased rapidly following the PEG treatment, exhibiting peaking values at 1 h, then returning to pre-stress levels, followed by a gradual increase. Similarly, both Na+-treated and Cl--treated trees exhibited a rapid rise of ABA after salt stress was initiated. Notably, salt-treated plants maintained a relatively higher ABA than PEG-treated plants in a longer term. Collectively, results suggest that osmotic stress and ion-specific effects were both responsible for salt-induced ABA in P. euphratica : the initial rapid increase of xylem ABA appears to be a consequence of an osmotic shock, whereas specific salt effects seem to be responsible for ABA accumulation later on. Compared with Cl--treated trees, a higher inhibitory effect on gas exchange (P-n and TRN) was observed in Na+-salt plants, resulting from its long-sustained ABA and higher salt concentrations in the xylem. Displacement of membrane-associated Ca2+ by Na+ and the lesser capacity in Na+ compartmentation in root vacuoles likely contribute to the high influx of Na+ and Cl- in Na+-treated plants. Xylem K+, Ca2+ and Mg2+ concentrations were elevated by external Na+ -salts and Cl--salts, suggesting that P. euphratica maintained a higher capacity in nutrient uptake under saline conditions, which makes a contribution to its salinity tolerance.展开更多
By solution culture experiment, three wheat genotypes (Ttiticum aestivum L.) and two oilseed rape genotypes (Brassica napus L.) differing in Mn efficiency under Mn-deficient conditions were used to study mechanisms of...By solution culture experiment, three wheat genotypes (Ttiticum aestivum L.) and two oilseed rape genotypes (Brassica napus L.) differing in Mn efficiency under Mn-deficient conditions were used to study mechanisms of the difference in Mn efficiency between wheat and oilseed rape. The results showed that there were significant differences in the abilities of MnIV reduction and acidification in root rhizosphere between the two species. Compared with wheat, oilseed rape had much higher reducing capacity and intensity of rhizosphere acidification under Mn-deficient conditions. Moreover, the higher ratio of functional leaves Mn/old leaves Mn in oilseed rape than in wheat was also an important factor for the different Mn efficiencies between the two species.展开更多
Nutrient limitation is known to inhibit growth and metabolism and to alter elemental stoichiometric ratios in phytoplankton. In this study, physiological changes in Thalassirosira weissflogii were measured under diffe...Nutrient limitation is known to inhibit growth and metabolism and to alter elemental stoichiometric ratios in phytoplankton. In this study, physiological changes in Thalassirosira weissflogii were measured under different dissolved inorganic phosphate (DIP) regimes in semi-continuous cultures to revisit the utility of the Redfield ratio for assessing nutrient limitation. The results showed that cell size increased with decreasing DIP availability. In the P-depleted treatment (f/2-P) the cell size was 1.48 times larger than that in the P-limited (f/100) treatment and 2.67 times larger than that in the P-saturated treatment (f/2 and f/10). The fucoxanthin to chlorophyll a ratio (Fuco/chl a) was relatively stable (about 0.3) in P-saturated cultures and was 10 times higher than that in P-limited and P-depleted cultures. During the experimental period, the photosynthetic efficiency index, ?F/Fm′, was relatively stable at ~0.50 in the P-saturated cultures, but quickly declined with decreasing DIP availability. Although cellular P content showed a significant difference between the P-saturated culture (1.6 pg/cell) and the P-limited culture (0.7 pg/cell), the N/P ratio in T. weissflogii did not show a trend with DIP availability and fluctuated slightly around 25. Our results suggest that cell division in T. weissflogii is not strictly size-gated but is probably regulated by a biochemical, and hence, an elemental stoichiometric ratio threshold, and that deviation of the cellular N/P ratio from the Redfield ratio is not a reliable indicator of algal nutrient stress.展开更多
The distribution of light fraction carbon (LF-C) in the various size classes of aggregates and its relationship to water- stable aggregates as well as the influence of cultivation on the organic components in virgin...The distribution of light fraction carbon (LF-C) in the various size classes of aggregates and its relationship to water- stable aggregates as well as the influence of cultivation on the organic components in virgin and cultivated black soils were studied by wet sieving and density separation methods. The total organic carbon (TOC) and LF-C were significantly higher (P≤ 0.05) in the virgin soils than in the cultivated soils. The LF-C in aggregates of different size classes varied from 0.9 to 2.5 g kg^-1 in the cultivated soils and from 2.5 to 7.1 g kg^-1 in the virgin soils, whereas the ratio of LF-C to TOC varied from 1.9% to 7.3% and from 5.0% to 12.2%, respectively. After being incubated under constant temperature and controlled humidity for three months, the contribution of LF-C to TOC sharply decreased to an amount (1.7%4.5%) close to the level in soils that had been cultivated for 20 to 25 years (1.3%-8.8%). As a result, the larger water-stable macro-aggregates (especially 〉 1 mm) decreased sharply, indicating that the LF-C pool in virgin soils declined quickly after cultivation, which reduced the water stability of soil aggregates.展开更多
A novel method for phase-detecting of each individual beam in coherent beam combining system of fiber laser array based on the property of time-shift of fast Fourier transform is reported. It takes advantage of the re...A novel method for phase-detecting of each individual beam in coherent beam combining system of fiber laser array based on the property of time-shift of fast Fourier transform is reported. It takes advantage of the relative movement of fringepattern to detect the phase shift between each individual beam and reference beam. No frequency shift component for reference beam is required in the system. At the same time, the acquisition fringe-pattern is firstly tailored to a few multiple of fringes in order to reduce the phase-detecting error caused by energy leakage during the course of fast Fourier transform. This technique can greatly reduce the effect of energy leakage and thus improve the phase-detecting precision. Basic principle of the new phase-detecting method is described in detail, and numerical results show that the phase-detecting error is less than 1/1000 wavelength bv utilizing our method.展开更多
Single-layer and multilayer laser additive manufacturing(LAM)for TC11 alloy with different Nd additions was conducted and the effect of Nd addition on microstructure and properties was studied.With the addition of Nd,...Single-layer and multilayer laser additive manufacturing(LAM)for TC11 alloy with different Nd additions was conducted and the effect of Nd addition on microstructure and properties was studied.With the addition of Nd,the aspect ratio of melting pools of single-layer specimens increases and the columnar-to-equiaxed transition occurs.The originalβgrain size andαplate width of TC11−1.0Nd are significantly reduced compared with those of pure TC11 specimens.It is proposed that the evenly distributed fine Nd_(2)O_(3) precipitates of about 1.51μm are formed preferentially during rapid solidification of melting pool,and they serve as heterogeneous nucleation particles to refine the microstructure in the subsequent solidification and solid-state phase transformation.Due to the multiple effects of Nd on the microstructure,the ultimate tensile strength of TC11−1.0Nd increases,while the yield strength,ductility and microhardness decrease compared with those of pure TC11.展开更多
A laser diode (LD) pumped Q switched high efficient intracavity frequency doubled Nd ∶YAG laser is reported here. The authors have designed an optical coupler and pointed out that the key to increasing harmonic conve...A laser diode (LD) pumped Q switched high efficient intracavity frequency doubled Nd ∶YAG laser is reported here. The authors have designed an optical coupler and pointed out that the key to increasing harmonic conversion efficiency is to decrease the loss of fundamental wave. In the experiments, a fundamental mode output laser was acquired. When the pumping power was 12 W, 2.6 W average output power at 1 064 nm with AO Q switch was obtained. 2.1 W average output power at 532 nm was obtained with intracavity frequency doubling, and the highest second harmonic conversion efficiency was 82 0 0.展开更多
A novel Eu^3+ rare earth complex, composed of 4 - hydroxybenzolate acid and 1, 10 - phenanthroline ligands was synthesized. The apparent morphology, composition, thermal stability and fluorescent property of the rare...A novel Eu^3+ rare earth complex, composed of 4 - hydroxybenzolate acid and 1, 10 - phenanthroline ligands was synthesized. The apparent morphology, composition, thermal stability and fluorescent property of the rare earth complex were measured by TEM, Element analysis, IR, TG and Fluorescence spectrometer. The results indicated that this rare earth complex has sphere-like morphology and its diameter was about 100 nm. The complex has good thermal stability due to the strong coordination between the Eu^3+ ions and the ligands. Based on the composition analysis, the complex structure formula was: Eu (HOC6 H4 COI)3 (phen) ·H2O Fluorescence spectra showed that the rare earth complex emission peaks were corresponding to the transition of ^5D0→7FJ(J=0,1,2,4),. and the highest intensity fluorescence peak was at 617 nm. The luminescent fiber was prepared by blending melt-spinning with rare earth complex and polypropylene resin. It also has a good luminescent quality, which the strongest emission peak was at 619 nm. It could be considered suitable for industrial application.展开更多
The strong adaptability of Broussonetia papyrifera (L.) Vent. to low phosphorus (P) conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, m...The strong adaptability of Broussonetia papyrifera (L.) Vent. to low phosphorus (P) conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, microelement contents are influenced by low-P stress, and their effects on the photosynthetic capability of B. pa- pyrifera remain unknown. In this study, we investigated the effects of low-P treatment on net photosynthetic rate (PN); chlorophyll a fluorescence (ChlF) characteristics; and Fe, Mn, Cu, and Zn contents of B. papyrifera and Morus alba L. seedlings. Results show that B. papyrifera exhibited better photosynthetic capability under moderate P defi- ciency (0.125, 0.063, and 0.031 mmol/L P treatments), whereas the photosynthetic capability of M. alba decreased under moderate and severe P deficiency (0.016 and 0 mmol/L P treatments). Under moderate P deficiency, the decrease in Cu and Zn contents in B. papyrifera was lower than that in M. alba. Under severe P deficiency, a consid- erable decrease of photosynthetic capability in B. pa- pyrifera and M. alba was associated with low Cu and Zn contents. The PN of the two Moraceae species exhibited a better correlation with Cu and Zn contents than with Fe or Mn content. P deficiency could not only decrease cyclic photophorylation and photosynthetic efficiency, but could also affect the stability of thylakoid membrane structureand electron transport efficiency by influencing the con- tents of Cu or Zn, thereby affecting photosynthesis.展开更多
A 3D finite element model was established to investigate the temperature and stress fields during the selective laser melting process of Al−Mg−Sc−Zr alloy.By considering the powder−solid transformation,temperaturedepe...A 3D finite element model was established to investigate the temperature and stress fields during the selective laser melting process of Al−Mg−Sc−Zr alloy.By considering the powder−solid transformation,temperaturedependent thermal properties,latent heat of phase transformations and molten pool convection,the effects of laser power,point distance and hatch spacing on the temperature distribution,molten pool dimensions and residual stress distribution were investigated.Then,the effects of laser power,point distance and hatch spacing on the microstructure,density and hardness of the alloy were studied by the experimental method.The results show that the molten pool size gradually increases as the laser power increases and the point distance and hatch spacing decrease.The residual stress mainly concentrates in the middle of the first scanning track and the beginning and end of each scanning track.Experimental results demonstrate the accuracy of the model.The density of the samples tends to increase and then decrease with increasing laser power and decreasing point distance and hatch spacing.The optimum process parameters are laser power of 325−375 W,point distance of 80−100μm and hatch spacing of 80μm.展开更多
Isothermal and cyclic oxidation behaviors of pure and yttrium-implanted nickel were studied at 1 000℃ in air. The oxide scales formed on nickel substrates were performed using SEM and TEM. It was found that Y-implant...Isothermal and cyclic oxidation behaviors of pure and yttrium-implanted nickel were studied at 1 000℃ in air. The oxide scales formed on nickel substrates were performed using SEM and TEM. It was found that Y-implantation greatly improved the anti-oxidation ability of nickel both in isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation and adhesion of oxide scale was Y-implantation greatly reduced the grain size of NiO and lowered the compressive stress within the scale. Yttrium implantation enhanced the adhesion of protective NiO oxide scale formed on nickel substrate.展开更多
The synthesis of some new diazo disperse dyes containing a pyrazol-5-one was described. The structures of the new products have been deduced from elemental analysis and spectral dada such as UV-Vis absorption, IR, ^1H...The synthesis of some new diazo disperse dyes containing a pyrazol-5-one was described. The structures of the new products have been deduced from elemental analysis and spectral dada such as UV-Vis absorption, IR, ^1H NMR, and MS spectroscopy. These dyestuffs gave satisfactory results when applied as disperse dyes to polyester fabric. The dyeing properties such as light fasmess, washing fastness and exhaustion studies have been investigated.展开更多
An indoor positioning system( IPS) is designed to realize positioning and tracking of mobile targets,by taking advantages of both the visible light communication( VLC) and inertial measurement unit( IMU). The platform...An indoor positioning system( IPS) is designed to realize positioning and tracking of mobile targets,by taking advantages of both the visible light communication( VLC) and inertial measurement unit( IMU). The platform of the IPS is designed,which consists of the light-emitting diode( LED)based transmitter,the receiver and the positioning server. To reduce the impact caused by measurement errors,both inertial sensing data and the received signal strength( RSS) from the VLC are calibrated. Then,a practical propagation model is established to obtain the distance between the transmitter and the receiver from the RSS measurements. Furthermore,a hybrid positioning algorithm is proposed by using the adaptive Kalman filter( AKF) and the weighted least squares( WLS)trilateration to estimate the positions of the mobile targets.Experimental results show that the developed IPS using the proposed hybrid positioning algorithm can extend the localization area of VLC,mitigate the IMU drifts and improve the positioning accuracy of mobile targets.展开更多
The method to measure the refractive index of the liquid-state metal is introduced. By inserting a wedge sample cell to the optical path of the Michelson interferometer, the refractive index of the liquid-state alloy ...The method to measure the refractive index of the liquid-state metal is introduced. By inserting a wedge sample cell to the optical path of the Michelson interferometer, the refractive index of the liquid-state alloy SCN-Eth is measured at different temperatures and densities. The results show that this method can be applied to measure the refractive index of various liquids, especially at different temperatures.展开更多
基金supported by the National Natural Science Foundation of China(5147807051108487)the Science and Technology Project from Chongqing Education Commission(KJ1400617)~~
文摘Ternary Ag/AgC l/BiO IO3 composite photocatalysts are prepared by a facile method. Enhanced visible-light absorption and charge carrier separation are achieved after the introduction of Ag/AgC l particles into BiO IO3 systems,as revealed by ultraviolet-visible diffuse-reflectance spectrometry,photocurrent response and electrochemical impedance spectroscopy. The Ag/AgC l/BiO IO3 composites are applied to the visible-light photocatalytic oxidization of NO in air and exhibit an enhanced activity for NO removal in comparison with Ag/AgC l and pure BiO IO3. A possible photocatalytic mechanism for Ag/AgC l/BiO IO3 is proposed,which is related to the surface plasmon resonance effects of Ag metal and the effective carrier separation ability of BiO IO3. This work provides insight into the design and preparation of BiO IO3-based materials with enhanced visible-light photocatalysis ability.
文摘We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (P-n) and unit transpiration rates (TRN) were both significantly decreased upon an osmotic shock caused by PEG 6000 solution (osmotic potential = -0.24 MPa) or a saline, which was applied by 50 mmol/L Na+-salts (NaNO3 : NaHCO3 : NaH2PO4 = 5 : 4 : 1, pH 6.8, osmotic potential = -0.24 MPa) or by 50 mmol/L Cl--salts (KCl : NH4Cl = 1:1, osmotic potential = -0.24 MPa). However, salt-treated P. euphratica plants maintained typically higher TRN than those exposed to PEG. Xylem ABA concentrations increased rapidly following the PEG treatment, exhibiting peaking values at 1 h, then returning to pre-stress levels, followed by a gradual increase. Similarly, both Na+-treated and Cl--treated trees exhibited a rapid rise of ABA after salt stress was initiated. Notably, salt-treated plants maintained a relatively higher ABA than PEG-treated plants in a longer term. Collectively, results suggest that osmotic stress and ion-specific effects were both responsible for salt-induced ABA in P. euphratica : the initial rapid increase of xylem ABA appears to be a consequence of an osmotic shock, whereas specific salt effects seem to be responsible for ABA accumulation later on. Compared with Cl--treated trees, a higher inhibitory effect on gas exchange (P-n and TRN) was observed in Na+-salt plants, resulting from its long-sustained ABA and higher salt concentrations in the xylem. Displacement of membrane-associated Ca2+ by Na+ and the lesser capacity in Na+ compartmentation in root vacuoles likely contribute to the high influx of Na+ and Cl- in Na+-treated plants. Xylem K+, Ca2+ and Mg2+ concentrations were elevated by external Na+ -salts and Cl--salts, suggesting that P. euphratica maintained a higher capacity in nutrient uptake under saline conditions, which makes a contribution to its salinity tolerance.
基金Project (No. 39425013) supported by the National Natural Science Foundation of China.
文摘By solution culture experiment, three wheat genotypes (Ttiticum aestivum L.) and two oilseed rape genotypes (Brassica napus L.) differing in Mn efficiency under Mn-deficient conditions were used to study mechanisms of the difference in Mn efficiency between wheat and oilseed rape. The results showed that there were significant differences in the abilities of MnIV reduction and acidification in root rhizosphere between the two species. Compared with wheat, oilseed rape had much higher reducing capacity and intensity of rhizosphere acidification under Mn-deficient conditions. Moreover, the higher ratio of functional leaves Mn/old leaves Mn in oilseed rape than in wheat was also an important factor for the different Mn efficiencies between the two species.
基金Supported by CAS for Key Topics in Innovation Engineering (No. KZCX2-YW-JS206)the CAS/SAFEA International Partnership Program for Creative Research Teams (No. KZCX2-YW-T001)+1 种基金the National Natural Science Foundation of China (Nos. 41076096, 40828006, U1033003)Guangdong Natural Science Fund (No. 2010B031900039)
文摘Nutrient limitation is known to inhibit growth and metabolism and to alter elemental stoichiometric ratios in phytoplankton. In this study, physiological changes in Thalassirosira weissflogii were measured under different dissolved inorganic phosphate (DIP) regimes in semi-continuous cultures to revisit the utility of the Redfield ratio for assessing nutrient limitation. The results showed that cell size increased with decreasing DIP availability. In the P-depleted treatment (f/2-P) the cell size was 1.48 times larger than that in the P-limited (f/100) treatment and 2.67 times larger than that in the P-saturated treatment (f/2 and f/10). The fucoxanthin to chlorophyll a ratio (Fuco/chl a) was relatively stable (about 0.3) in P-saturated cultures and was 10 times higher than that in P-limited and P-depleted cultures. During the experimental period, the photosynthetic efficiency index, ?F/Fm′, was relatively stable at ~0.50 in the P-saturated cultures, but quickly declined with decreasing DIP availability. Although cellular P content showed a significant difference between the P-saturated culture (1.6 pg/cell) and the P-limited culture (0.7 pg/cell), the N/P ratio in T. weissflogii did not show a trend with DIP availability and fluctuated slightly around 25. Our results suggest that cell division in T. weissflogii is not strictly size-gated but is probably regulated by a biochemical, and hence, an elemental stoichiometric ratio threshold, and that deviation of the cellular N/P ratio from the Redfield ratio is not a reliable indicator of algal nutrient stress.
基金Project supported by the State Key Basic Research Development Program (No. G1999011804) the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCXZ-SW-416).
文摘The distribution of light fraction carbon (LF-C) in the various size classes of aggregates and its relationship to water- stable aggregates as well as the influence of cultivation on the organic components in virgin and cultivated black soils were studied by wet sieving and density separation methods. The total organic carbon (TOC) and LF-C were significantly higher (P≤ 0.05) in the virgin soils than in the cultivated soils. The LF-C in aggregates of different size classes varied from 0.9 to 2.5 g kg^-1 in the cultivated soils and from 2.5 to 7.1 g kg^-1 in the virgin soils, whereas the ratio of LF-C to TOC varied from 1.9% to 7.3% and from 5.0% to 12.2%, respectively. After being incubated under constant temperature and controlled humidity for three months, the contribution of LF-C to TOC sharply decreased to an amount (1.7%4.5%) close to the level in soils that had been cultivated for 20 to 25 years (1.3%-8.8%). As a result, the larger water-stable macro-aggregates (especially 〉 1 mm) decreased sharply, indicating that the LF-C pool in virgin soils declined quickly after cultivation, which reduced the water stability of soil aggregates.
基金Supported by the National Natural Science Founda-tion of China (60678018)
文摘A novel method for phase-detecting of each individual beam in coherent beam combining system of fiber laser array based on the property of time-shift of fast Fourier transform is reported. It takes advantage of the relative movement of fringepattern to detect the phase shift between each individual beam and reference beam. No frequency shift component for reference beam is required in the system. At the same time, the acquisition fringe-pattern is firstly tailored to a few multiple of fringes in order to reduce the phase-detecting error caused by energy leakage during the course of fast Fourier transform. This technique can greatly reduce the effect of energy leakage and thus improve the phase-detecting precision. Basic principle of the new phase-detecting method is described in detail, and numerical results show that the phase-detecting error is less than 1/1000 wavelength bv utilizing our method.
基金financially supported by the National Natural Science Foundation of China(Nos.51801009,52071005)the Youth Talent Support Program of Beihang University,China(No.YWF-21-BJ-J-1143)Shuangyiliu Fund of Beihang University,China(No.030810)。
文摘Single-layer and multilayer laser additive manufacturing(LAM)for TC11 alloy with different Nd additions was conducted and the effect of Nd addition on microstructure and properties was studied.With the addition of Nd,the aspect ratio of melting pools of single-layer specimens increases and the columnar-to-equiaxed transition occurs.The originalβgrain size andαplate width of TC11−1.0Nd are significantly reduced compared with those of pure TC11 specimens.It is proposed that the evenly distributed fine Nd_(2)O_(3) precipitates of about 1.51μm are formed preferentially during rapid solidification of melting pool,and they serve as heterogeneous nucleation particles to refine the microstructure in the subsequent solidification and solid-state phase transformation.Due to the multiple effects of Nd on the microstructure,the ultimate tensile strength of TC11−1.0Nd increases,while the yield strength,ductility and microhardness decrease compared with those of pure TC11.
文摘A laser diode (LD) pumped Q switched high efficient intracavity frequency doubled Nd ∶YAG laser is reported here. The authors have designed an optical coupler and pointed out that the key to increasing harmonic conversion efficiency is to decrease the loss of fundamental wave. In the experiments, a fundamental mode output laser was acquired. When the pumping power was 12 W, 2.6 W average output power at 1 064 nm with AO Q switch was obtained. 2.1 W average output power at 532 nm was obtained with intracavity frequency doubling, and the highest second harmonic conversion efficiency was 82 0 0.
基金Supported by the Innovation Fund of Donghua University for Doctors
文摘A novel Eu^3+ rare earth complex, composed of 4 - hydroxybenzolate acid and 1, 10 - phenanthroline ligands was synthesized. The apparent morphology, composition, thermal stability and fluorescent property of the rare earth complex were measured by TEM, Element analysis, IR, TG and Fluorescence spectrometer. The results indicated that this rare earth complex has sphere-like morphology and its diameter was about 100 nm. The complex has good thermal stability due to the strong coordination between the Eu^3+ ions and the ligands. Based on the composition analysis, the complex structure formula was: Eu (HOC6 H4 COI)3 (phen) ·H2O Fluorescence spectra showed that the rare earth complex emission peaks were corresponding to the transition of ^5D0→7FJ(J=0,1,2,4),. and the highest intensity fluorescence peak was at 617 nm. The luminescent fiber was prepared by blending melt-spinning with rare earth complex and polypropylene resin. It also has a good luminescent quality, which the strongest emission peak was at 619 nm. It could be considered suitable for industrial application.
基金supported by the project of the National Natural Science Foundation of China (No. 31301243)a project funded by the Priority Academic Program Development of Jiangsu higher education institutions (PAPD)+1 种基金the research foundation for introduce talents of Jiangsu university (13JDG030)the brainstorm project on social development of Guizhou Province (SY[2010]3043)
文摘The strong adaptability of Broussonetia papyrifera (L.) Vent. to low phosphorus (P) conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, microelement contents are influenced by low-P stress, and their effects on the photosynthetic capability of B. pa- pyrifera remain unknown. In this study, we investigated the effects of low-P treatment on net photosynthetic rate (PN); chlorophyll a fluorescence (ChlF) characteristics; and Fe, Mn, Cu, and Zn contents of B. papyrifera and Morus alba L. seedlings. Results show that B. papyrifera exhibited better photosynthetic capability under moderate P defi- ciency (0.125, 0.063, and 0.031 mmol/L P treatments), whereas the photosynthetic capability of M. alba decreased under moderate and severe P deficiency (0.016 and 0 mmol/L P treatments). Under moderate P deficiency, the decrease in Cu and Zn contents in B. papyrifera was lower than that in M. alba. Under severe P deficiency, a consid- erable decrease of photosynthetic capability in B. pa- pyrifera and M. alba was associated with low Cu and Zn contents. The PN of the two Moraceae species exhibited a better correlation with Cu and Zn contents than with Fe or Mn content. P deficiency could not only decrease cyclic photophorylation and photosynthetic efficiency, but could also affect the stability of thylakoid membrane structureand electron transport efficiency by influencing the con- tents of Cu or Zn, thereby affecting photosynthesis.
基金financial supports from the National Natural Science Foundation of China (No.51804349)the China Postdoctoral Science Foundation (No.2018M632986)+1 种基金the Natural Science Foundation of Hunan Province,China (No.2019JJ50766)the National Key Laboratory of Science and Technology on High-strength Structural Materials,China (No.JCKY201851)。
文摘A 3D finite element model was established to investigate the temperature and stress fields during the selective laser melting process of Al−Mg−Sc−Zr alloy.By considering the powder−solid transformation,temperaturedependent thermal properties,latent heat of phase transformations and molten pool convection,the effects of laser power,point distance and hatch spacing on the temperature distribution,molten pool dimensions and residual stress distribution were investigated.Then,the effects of laser power,point distance and hatch spacing on the microstructure,density and hardness of the alloy were studied by the experimental method.The results show that the molten pool size gradually increases as the laser power increases and the point distance and hatch spacing decrease.The residual stress mainly concentrates in the middle of the first scanning track and the beginning and end of each scanning track.Experimental results demonstrate the accuracy of the model.The density of the samples tends to increase and then decrease with increasing laser power and decreasing point distance and hatch spacing.The optimum process parameters are laser power of 325−375 W,point distance of 80−100μm and hatch spacing of 80μm.
文摘Isothermal and cyclic oxidation behaviors of pure and yttrium-implanted nickel were studied at 1 000℃ in air. The oxide scales formed on nickel substrates were performed using SEM and TEM. It was found that Y-implantation greatly improved the anti-oxidation ability of nickel both in isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation and adhesion of oxide scale was Y-implantation greatly reduced the grain size of NiO and lowered the compressive stress within the scale. Yttrium implantation enhanced the adhesion of protective NiO oxide scale formed on nickel substrate.
文摘The synthesis of some new diazo disperse dyes containing a pyrazol-5-one was described. The structures of the new products have been deduced from elemental analysis and spectral dada such as UV-Vis absorption, IR, ^1H NMR, and MS spectroscopy. These dyestuffs gave satisfactory results when applied as disperse dyes to polyester fabric. The dyeing properties such as light fasmess, washing fastness and exhaustion studies have been investigated.
基金The National Natural Science Foundation of China(No.61741102,61471164,61601122)the Fundamental Research Funds for the Central Universities(No.SJLX_160040)
文摘An indoor positioning system( IPS) is designed to realize positioning and tracking of mobile targets,by taking advantages of both the visible light communication( VLC) and inertial measurement unit( IMU). The platform of the IPS is designed,which consists of the light-emitting diode( LED)based transmitter,the receiver and the positioning server. To reduce the impact caused by measurement errors,both inertial sensing data and the received signal strength( RSS) from the VLC are calibrated. Then,a practical propagation model is established to obtain the distance between the transmitter and the receiver from the RSS measurements. Furthermore,a hybrid positioning algorithm is proposed by using the adaptive Kalman filter( AKF) and the weighted least squares( WLS)trilateration to estimate the positions of the mobile targets.Experimental results show that the developed IPS using the proposed hybrid positioning algorithm can extend the localization area of VLC,mitigate the IMU drifts and improve the positioning accuracy of mobile targets.
文摘The method to measure the refractive index of the liquid-state metal is introduced. By inserting a wedge sample cell to the optical path of the Michelson interferometer, the refractive index of the liquid-state alloy SCN-Eth is measured at different temperatures and densities. The results show that this method can be applied to measure the refractive index of various liquids, especially at different temperatures.