Significant progress has been made in the development of non-precious metal electrocatalysts （NPMEs） during the past decade. Correspondingly, there is an urgent demand for an appropriate measurement method to be est...Significant progress has been made in the development of non-precious metal electrocatalysts （NPMEs） during the past decade. Correspondingly, there is an urgent demand for an appropriate measurement method to be established for the reliable evaluation of NPMEs. In this study, platinum and graphite counter electrodes were used to investigate the impact of counter electrode material on the accelerated durability testing （ADT） of NPMEs in acidic medium. Platinum used as the coun- ter electrode in a traditional three-electrode electrochemical cell was found to dissolve in acidic medium and re-deposit on NPME coated on the working electrode during ADT. Such re-deposition causes the oxygen reduction reaction （ORR） performance of NPMEs to remarkably improve, and thus will seriously mislead our judgment of NPMEs if we are unaware of it. The phenomenon can be avoided using a graphite counter electrode.展开更多
Information on seed vigor of the vegetable crops is always important and necessary due to the increasing demand of high quality seeds for sowing and high-value commercial. The cultivation of these species, conducted i...Information on seed vigor of the vegetable crops is always important and necessary due to the increasing demand of high quality seeds for sowing and high-value commercial. The cultivation of these species, conducted intensively, should be established with seed high potential physiological and health for the development of a more productive and sustainable agriculture. The present study was conducted to evaluate the potential physiological of seed lots of radish and coriander. The experiment was conducted at the laboratory of seed analysis and greenhouse of the plant science department of the Federal University of Pelotas in South Brazil. Four radish seed lots, cultivar ＂Saxa＂, and four coriander seed lots, cultivar ＂Verdito＂ were used. Germination seed test, first count of germination, accelerated aging test, electrical conductivity and seedling emergence were used to evaluate the physiological quality of the lots. The experimental design was completely randomized design with five replications. Means were compared by Tukey test. The accelerated aging test was the most efficient test in assessing the physiological quality for both lots of radish seeds and coriander and this test provide coherent results with seedlings emergence.展开更多
To acquire a rational minimum cut-off time and the precision of lifetime prediction with respect to cut-off time for the accelerated aging test of LED lamps, fifth-order moving average error estimation is adopted in t...To acquire a rational minimum cut-off time and the precision of lifetime prediction with respect to cut-off time for the accelerated aging test of LED lamps, fifth-order moving average error estimation is adopted in this paper. Eighteen LED lamps from the same batch are selected for two accelerated aging tests, with 10 samples at 80 ℃ and eight samples at 85 ℃. First, the accelerated lifetime of each lamp is acquired by exponential fitting of the lumen maintenances of the lamp for a certain cut-offtime With the acquired lifetimes of all lamps, the two-parameter Weibull distribution of the failure probability is obtained, and the medium lifetime is calculated. Then, the precision of the medium lifetime prediction for different cut-off times is obtained by moving average error estimation. It is shown that there exists a minimum cut-off time for the accelerated aging test, which can be determined by the variation of the moving average error versus the cut-offtime. When the cut-off time is less than this value, the lifetime estimation is irrational. For a given cut-off time, the precision of lifetime prediction can be computed by average error evaluation, and the error of lifetime estimation decreases gradually as the cut-off time- increases. The minimum cut-off time and medium lifetime of LED lamps are both sensitive to thermal stress. The minimum cut-off time is 1104 h with the lifetime esti- mation error of 1.15% for the test at 80 ~C, and 936 h with the lifetime estimation error of 1.24% for the test at 85 ℃. With the lifetime estimation error of about 0.46%, the median lifetimes are 7310 h and 4598 h for the tests at 80 ℃ and 85℃, respectively.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(DUT15RC(3)001,DUT15ZD225)the Program for Liao-ning Excellent Talents in University(LR2015014)+1 种基金the Liaoning BaiQianWan Talents Program(201519)Dalian Excellent Young Scientific and Technological Talents(2015R006)
文摘Significant progress has been made in the development of non-precious metal electrocatalysts （NPMEs） during the past decade. Correspondingly, there is an urgent demand for an appropriate measurement method to be established for the reliable evaluation of NPMEs. In this study, platinum and graphite counter electrodes were used to investigate the impact of counter electrode material on the accelerated durability testing （ADT） of NPMEs in acidic medium. Platinum used as the coun- ter electrode in a traditional three-electrode electrochemical cell was found to dissolve in acidic medium and re-deposit on NPME coated on the working electrode during ADT. Such re-deposition causes the oxygen reduction reaction （ORR） performance of NPMEs to remarkably improve, and thus will seriously mislead our judgment of NPMEs if we are unaware of it. The phenomenon can be avoided using a graphite counter electrode.
文摘Information on seed vigor of the vegetable crops is always important and necessary due to the increasing demand of high quality seeds for sowing and high-value commercial. The cultivation of these species, conducted intensively, should be established with seed high potential physiological and health for the development of a more productive and sustainable agriculture. The present study was conducted to evaluate the potential physiological of seed lots of radish and coriander. The experiment was conducted at the laboratory of seed analysis and greenhouse of the plant science department of the Federal University of Pelotas in South Brazil. Four radish seed lots, cultivar ＂Saxa＂, and four coriander seed lots, cultivar ＂Verdito＂ were used. Germination seed test, first count of germination, accelerated aging test, electrical conductivity and seedling emergence were used to evaluate the physiological quality of the lots. The experimental design was completely randomized design with five replications. Means were compared by Tukey test. The accelerated aging test was the most efficient test in assessing the physiological quality for both lots of radish seeds and coriander and this test provide coherent results with seedlings emergence.
基金supported by the National High-Tech R&D Program(863)of China(Nos.2015AA03A101 and 2013AA03A116)the Cui Can Project of Chinese Academy of Sciences(No.KZCC-EW-102)
文摘To acquire a rational minimum cut-off time and the precision of lifetime prediction with respect to cut-off time for the accelerated aging test of LED lamps, fifth-order moving average error estimation is adopted in this paper. Eighteen LED lamps from the same batch are selected for two accelerated aging tests, with 10 samples at 80 ℃ and eight samples at 85 ℃. First, the accelerated lifetime of each lamp is acquired by exponential fitting of the lumen maintenances of the lamp for a certain cut-offtime With the acquired lifetimes of all lamps, the two-parameter Weibull distribution of the failure probability is obtained, and the medium lifetime is calculated. Then, the precision of the medium lifetime prediction for different cut-off times is obtained by moving average error estimation. It is shown that there exists a minimum cut-off time for the accelerated aging test, which can be determined by the variation of the moving average error versus the cut-offtime. When the cut-off time is less than this value, the lifetime estimation is irrational. For a given cut-off time, the precision of lifetime prediction can be computed by average error evaluation, and the error of lifetime estimation decreases gradually as the cut-off time- increases. The minimum cut-off time and medium lifetime of LED lamps are both sensitive to thermal stress. The minimum cut-off time is 1104 h with the lifetime esti- mation error of 1.15% for the test at 80 ~C, and 936 h with the lifetime estimation error of 1.24% for the test at 85 ℃. With the lifetime estimation error of about 0.46%, the median lifetimes are 7310 h and 4598 h for the tests at 80 ℃ and 85℃, respectively.
