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[Effect of fertilization on soil respiration in the Stipa breviflora desert steppe of inner mongolia].
Ying Yong Sheng Tai Xue Bao
PUBLISHED: 07-03-2014
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In 2012, a field experiment with different fertilizer treatments was conducted in the Stipa breviflora desert steppe of Inner Mongolia. The LI-8100 was used to investigate daily and seasonal variations of soil respiration rate, and the relationships between soil respiration rate and environmental factors were analyzed. The results showed that: 1) In the rapidly growing stage (August), the respiration rate in 10 g N x m(-2) was significantly higher than in the other treatments. No significant differences were observed among 5 g N x m(-2), 2.5 g N x m(-2) and CK. 2) During the early and middle growing stage (May to September), P fertilizer improved the soil respiration rate. 3) Fertilization did not change the daily and seasonal variations of soil respiration. The daily variations of soil respiration of all fertilization treatments were almost the same, with the highest values occurring within 10:00-14:00 and the lowest values occurring within 03:00-05:00. The peak of seasonal variation occurred in August. 4) The soil respiration rate was significantly related to soil temperature at 5 cm depth and soil moisture at 0-10 cm depth, and the determined coefficients were 0.40-0.58 and 0.51-0.70, respectively, indicating that soil moisture was the major factor affecting soil respiration.
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[Using atomic fluorescence spectrometry to study the spatial distribution of As and Hg in orchard soils].
Guang Pu Xue Yu Guang Pu Fen Xi
PUBLISHED: 05-15-2014
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Aqua regia digestion, double channels-atomic fluorescence spectrometry method was used to determine the concentrations of As and Hg in orchard soils of Qixia City - the main apple production area of Shandong province. Validate The detection limitation, accuracy and precision of the method were validated, the spatial distribution was analyzed, and the characteristics of As and Hg pollution in Qixia orchard soils were assessed. The results showed that the range of As concentration in Qixia soils is between 2.79 and 20.93 mg x kg(-1), the average concentration is 10.59 mg x kg(-1), the range of Hg concentration in Qixia soil is between 0.01 and 0.79 mg x kg(-1), the average concentration is 0.12 mg x kg(-1). The variation of As concentration in soils is small, whereas that of Hg concentration is large. Frequency distribution graphics of As and Hg showed that the concentration of As in soils is according with the normal distribution approximately and the concentrations are mostly between 7 and 15 mg x kg(-1), the concentration of Hg in soil isn't according with the normal distribution and the concentrations are mostly between 0.03 and 0.21 mg x kg(-1). The correlations between the concentrations of As or Hg in soils and the nutrient are not significant and there is no significant correlation even between As and Hg. Based on the environmental technical terms for green food production area, the As concentration in orchard soil of Qixia City is at clean level, but there are 4.76% of sample points with Hg pollution index exceeding 1, and this should be attracted the attention of the administrators.
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[What is sustainability science?].
Ying Yong Sheng Tai Xue Bao
PUBLISHED: 04-29-2014
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Sustainability is the theme of our time and also the grandest challenge to humanity. Since the 1970s, the term, sustainable development, has frequently appeared in the scientific literature, governmental documents, media promotions for public goods, and commercial advertisements. However, the science that provides the theoretical foundation and practical guidance for sustainable development--sustainability science--only began to emerge in the beginning of the 21st century. Nevertheless, the field has rapidly developed in depth and expanded in scope during the past decade, with its core concepts and research methods coalescing. China, as the most populous country in the world and home to the philosophical root of sustainability science-the unity of man and nature, is obligated to take upon the challenge of our time, to facilitate global sustainability while pursuing the Chinese Dream, and to play a leading role in the development of sustainability science. Toward this grandiose goal, this paper presents the first Chinese introduction to sustainability science, which discusses its basic concepts, research questions, and future directions. Sustainability science is the study of the dynamic relationship between humans and the environment, particularly focusing on the vulnerability, robustness, resilience, and stability of the coupled human-environment system. It is a transdisciplinary science that integrates natural sciences with humanities and social sciences. It hinges on the environment-economy-society nexus, and merges basic and applied research. The key components of sustainability often change with time, place, and culture, and thus sustainability science needs to emphasize multi-scale studies in space and time, with emphasis on landscapes and regions over a horizon of 50 to 100 years. It needs to focus on the relationship between ecosystem services and human well-being, as influenced by biodiversity and ecosystem processes as well as climate change, land use change, and other socioeconomic drivers. Landscape sustainability is at the core of sustainability science, and is expected to be a hot research topic in the next few decades.
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Hybrid mesoporous colloid photonic crystal array for high performance vapor sensing.
Nanoscale
PUBLISHED: 04-28-2014
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A hybrid mesoporous photonic crystal vapor sensing chip was developed by introducing fluorescent dyes into mesoporous colloidal crystals. The sensing chip was capable of discriminating various kinds of vapors, as well as their concentrations, according to their fluorescence and reflective responses to vapor analytes.
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Cucurbitane-type triterpenoids from the leaves of Momordica charantia.
J Asian Nat Prod Res
PUBLISHED: 02-05-2014
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Phytochemical investigation of the ethanol extract from the leaves of Momordica charantia L. led to the isolation of two new (1, 2) and four known (3-6) cucurbitane-type triterpenoids. Their structures were elucidated on the basis of extensive analyses of spectroscopic data including IR, UV, MS, 1D, and 2D NMR. Also the absolute configurations of momordicines I (3) and II (4) were determined for the first time by application of the modified Mosher's method, acid hydrolysis, and GC analysis.
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Anisotropic colloidal crystal particles from microfluidics.
J Colloid Interface Sci
PUBLISHED: 01-20-2014
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Anisotropic colloidal crystal particles (CCPs) have showed their great potential in biotechnology and structural materials due to their anisotropic shapes and tunable optical property. However, their controllable generation is still a challenge. Here, a novel microfluidic approach is developed to generate anisotropic CCPs. The microfluidic device is composed of an injection capillary and a collection capillary with available size and shape. Based on the device, the anisotropic particles with non-close-packed colloidal crystal structures are achieved by photo-polymerizing droplet templates in a confined collection capillary with different shapes and sizes. Moreover, anisotropic close-packed CCPs can be made from non-close-packed CCPs through a thermal process. It is demonstrated that the anisotropic CCPs in different sizes, structural colors and shapes (rods, cuboids and disks) can be generated. These distinguishable features of resultant particles make them ideal barcodes for high-throughput bioassays. In order to prove it, DNA multiplex detection is carried out. The experimental results indicate that achieved particles have a great encoding capacity and are highly practical for multiplex coding bioassays. Therefore, we believe that the anisotropic CCPs would be highly promising barcodes in biomedical applications, including high-throughput bioassays and cell culture research where multiplexing is needed.
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New strategy for surface functionalization of periodic mesoporous silica based on meso-HSiO1.5.
J. Am. Chem. Soc.
PUBLISHED: 01-16-2014
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Organic functionalization of periodic mesoporous silicas (PMSs) offers a way to improve their excellent properties and wide applications owing to their structural superiority. In this study, a new strategy for organic functionalization of PMSs is demonstrated by hydrosilylation of the recently discovered "impossible" periodic mesoporous hydridosilica, meso-HSiO1.5. This method overcomes the disadvantages of present pathways for organic functionalization of PMSs with organosilica. Moreover, compared to the traditional functionalization on the surface of porous silicon by hydrosilylation, the template-synthesized meso-HSiO1.5 is more flexible to access functional-groups-loaded PMSs with adjustable microstructures. The new method and materials will have wider applications based on both the structure and surface superiorities.
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Characterization of multi-dye pressure-sensitive microbeads.
Rev Sci Instrum
PUBLISHED: 12-03-2013
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The response times of pressure-sensitive particles to passing shockwaves were measured to investigate their ability to accurately determine pressure changes in unsteady flows. The particles tested were loaded with novel pressure-sensitive dyes such as Pt (II) meso-tetra(pentafluorophenyl)porphine, Pt(II) octaethylporphine, bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl))iridium III, and iridium(III) bis(4-phenylthieno[3,2-c] pyridinato-N,C2)acetylacetonate. For this work, porous silicon dioxide pressure-sensitive beads (PSBeads) were used. Two synthetic procedures were used to fabricate the particles. In the first, a one-step method loaded dyes during the synthesis of microbeads, in the second a two-step method synthesized the microbeads first, then loaded the dyes. The shock tube facility was used to measure the response times of microbeads to fast pressure jumps. The study involved testing multiple luminophors loaded in microbeads with various size distributions. Response times for the silica-based microbeads ranged between 26 ?s and 462 ?s (at 90% of the amplitude response), which are much faster than previously reported polystyrene-based microbead response times, which range from 507 ?s to 1582 ?s (at 90% of the amplitude response) [F. Kimura, M. Rodriguez, J. McCann, B. Carlson, D. Dabiri, G. Khalil, J. B. Callis, Y. Xia, and M. Gouterman, "Development and characterization of fast responding pressure sensitive microspheres," Rev. Sci. Instrum. 79, 074102 (2008)].
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[Cleistogenes squarrosa population at different restorative succession stages in Inner Mongolia of China: a point pattern analysis].
Ying Yong Sheng Tai Xue Bao
PUBLISHED: 11-02-2013
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In this paper, the spatial pattern of Cleistogenes squarrosa population in different restorative succession communities of the typical steppe dominated by Stipa grandis and Leymus chinensis in Inner Mongolia was measured by photography orientation, and analyzed by complete spatial randomness model, Poisson cluster process, and nested double-cluster process. In severely degraded community, C. squarrosa population fitted well nested double-cluster process for all scales, i. e., high density small clusters existed at the centers of large clusters; whereas in 5-, 8-, and 21-year-old restored communities, C. squarrosa population fitted well Poisson cluster process for all scales, i. e. , high density small clusters did not exist at the centers of the clusters. It was suggested that facilitation was the dominant interaction in severely degraded community, while competition dominated in restored communities. The differences in the spatial pattern of C. squarrosa population during the restorative succession could be induced by the shift from facilitation to competition along the gradient of grazing stress.
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[Estimation of chlorophyll content in apple tree canopy based on hyperspectral parameters].
Guang Pu Xue Yu Guang Pu Fen Xi
PUBLISHED: 10-29-2013
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The hyperspectral reflectance of apple tree canopy during spring shoots stopping growth period was measured using ASD FieldSpec3 field spectrometer. Original spectral data were processed in deviation forms, and significant spectrum parameters correlated with chlorophyll content were found out with correlation analysis. The best vegetation indices were chosen and the apple canopy chlorophyll content estimation model was established by analyzing vegetation index of two-band combination in the sensitive region 400-1 350 nm. The result showed that (1) The sensitive band region of apple canopy chlorophyll content is 400-1 350 nm. (2) The vegetation index CCI(D(794)/D(763)) can commendably estimate the apple canopy chlorophyll content. (3) The model with CCI(D(794)/D(763)) as the independent variables was determined to be the best for chlorophyll content prediction of apple tree canopy. Therefore, using hyperspectral technology can estimate apple canopy chlorophyll content more rapidly and accurately, and provides a theoretical basis for rapid apple tree canopy nutrition diagnosis and growth monitoring.
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[Establishment of a complete daily time series of precipitation and its change characteristics in forest region of eastern china during 1961-2010].
Ying Yong Sheng Tai Xue Bao
PUBLISHED: 08-01-2013
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To accurately interpolate the missing precipitation data from meteorological observation stations within a region to obtain a complete precipitation series is of significance in improving the spatial and temporal resolution in analyzing the effects of climate change. By using spatial correlation and stepwise regression techniques, this paper interpolated the missing precipitation data for an individual day or less than 7 days in a month from the 853 meteorological stations in the forest region of Eastern China in 1961-2010, as a consequent establishment of the complete time series precipitation datasets of the observation stations in 1961-2010 established. Based on these, trend analysis approach was applied to analyze the variation characteristics of the annual precipitation, annual precipitation days, and extreme precipitation events in the region in 1961-2010. During the study period, the annual precipitation in the region presented an insignificant increasing trend, with a tendency of 5.58 mm (10 a) -1, but the decadal variation was obvious. The annual precipitation days reduced significantly, while the annual extreme precipitation days and extreme precipitation volumes increased significantly, with a tendency of 0.12 d (10 a) -1 and 10. 22 mm (10 a)-1, respectively. Since the 1990s, the extreme precipitation events became frequently and intensively, and the proportion of the volumes of extreme precipitation to total precipitation increased significantly. Both the extreme precipitation days and the volumes of extreme precipitation had an abrupt change in 1993.
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[Hyperspectral estimation of kalium content in apple florescence canopy based on fuzzy recognition].
Guang Pu Xue Yu Guang Pu Fen Xi
PUBLISHED: 07-12-2013
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The objective of the present paper is fast and nondestructive estimate of kalium content using ASD FieldSpec3 spectrometer determined hyperspectral data in apple florescence canopy. According to detection of hyperspectral data of the apple florescence canopy and kalium content data at laboratory in Qixia city of experimental orchards in 2008 and 2009, the correlation analysis of hyperspectral reflectance and its eleven transforms with kalium content was proceeded. The biggest correlation coefficient as independent variable and the estimation model of kalium content were established based on fuzzy recognition algorithms. The model was tested by sample inspection in 2008 and verified by data in 2009. The results showed that the correlation is less for the original spectral reflectance (R) and its reciprocal(1/R), logarithm (lgR), square root (R1/2) and the kalium content, but it is enhanced obviously for their first derivative and second derivative. The correlation coefficient(r) of kalium content estimating model y = 11.344 5h + 1.309 7 is 0.985 1, the total root mean square difference (RMSE) is 0.355 7 and F statistics is 3 085.6. The average relative error of measured values and estimated values for 24 inspection sample is 9.8%, estimation accuracy is 90.2% and verification accuracy is 83.3% utilizing test data in 2009. It was showed that this model is more stable by estimating apple florescence canopy of kalium content and the model precision is able to meet the needs of production.
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Aqueous-phase synthesis of single-crystal Pd seeds 3 nm in diameter and their use for the growth of Pd nanocrystals with different shapes.
Chemistry
PUBLISHED: 01-14-2013
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This article describes an aqueous method for the synthesis of Pd seeds with a single-crystal structure and a uniform diameter of 3 nm and their use for the growth of Pd nanocrystals with a variety of shapes. We have also investigated the effects of a number of parameters, including the temperature, reducing power of the reductant, and capping agent on the reduction rate of a Pd precursor, and thus the final size, size distribution, and morphology of the Pd seeds. By taking advantage of the coordination effect of Br(-) ions with Pd(2+) ions and their selective adsorption on the Pd(100) surface, Pd nanocrystals with a number of distinct shapes could be conveniently produced by varying the concentration of KBr added into the growth solution. This work provides a general and facile method for the green synthesis of Pd nanocrystals with controlled shapes, especially for the preparation of Pd nanocrystals with sizes in the sub-10 nm regime.
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[Hyper-spectral estimation of soil organic matter content based on wavelet transformation].
Ying Yong Sheng Tai Xue Bao
PUBLISHED: 08-11-2011
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A total of 60 soil samples with approximate contents of N, P, and K and greatly different content of organic matter were selected by statistical analysis. Through hyper-spectral detection and analysis, the first derivative spectrum of the soil logarithmic reflectance was obtained, and was decomposed by the Bior 1.3 wavelet function. The approximative signal of the lowest frequency and the noise signal of the highest frequency were removed from the input spectrum so as to obtain the characteristic spectrum corresponding to soil physical and chemical parameters. The sensitive bands of soil organic matter were selected by correlation analysis, and the forecasting models were built by multiple regression analysis, based on the sensitive bands and the characteristic spectrum, respectively. Through comparison analysis, the optimal wavelet decomposing resolution for extracting the characteristic spectrum of soil organic matter was ascertained, and the best forecasting model was established. The best wavelet decomposing resolution was 9, followed by 8 and 10. Based on the characteristic spectrum of wavelet decomposing of 9 resolutions, the model R2 reached 0.89, which was increased by 0.31 as compared to the model based on sensitive bands, and increased by 0.10 as compared to the model based on the original spectrum.
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[Quantitative models between canopy hyperspectrum and its component features at apple tree prosperous fruit stage].
Guang Pu Xue Yu Guang Pu Fen Xi
PUBLISHED: 12-09-2010
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Hyperspectral technique has become the basis of quantitative remote sensing. Hyperspectrum of apple tree canopy at prosperous fruit stage consists of the complex information of fruits, leaves, stocks, soil and reflecting films, which was mostly affected by component features of canopy at this stage. First, the hyperspectrum of 18 sample apple trees with reflecting films was compared with that of 44 trees without reflecting films. It could be seen that the impact of reflecting films on reflectance was obvious, so the sample trees with ground reflecting films should be separated to analyze from those without ground films. Secondly, nine indexes of canopy components were built based on classified digital photos of 44 apple trees without ground films. Thirdly, the correlation between the nine indexes and canopy reflectance including some kinds of conversion data was analyzed. The results showed that the correlation between reflectance and the ratio of fruit to leaf was the best, among which the max coefficient reached 0.815, and the correlation between reflectance and the ratio of leaf was a little better than that between reflectance and the density of fruit. Then models of correlation analysis, linear regression, BP neural network and support vector regression were taken to explain the quantitative relationship between the hyperspectral reflectance and the ratio of fruit to leaf with the softwares of DPS and LIBSVM. It was feasible that all of the four models in 611-680 nm characteristic band are feasible to be used to predict, while the model accuracy of BP neural network and support vector regression was better than one-variable linear regression and multi-variable regression, and the accuracy of support vector regression model was the best. This study will be served as a reliable theoretical reference for the yield estimation of apples based on remote sensing data.
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[Standardization of technical methods for apple florescence canopy spectral detection].
Guang Pu Xue Yu Guang Pu Fen Xi
PUBLISHED: 08-17-2010
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Aiming at spectral detection of apple florescence canopy, the present paper carried out spectral detection tests under different weather conditions, different detection times, and different detection heights and angles to apple canopy in the two years of 2008 and 2009, so as to analyze impacts of these factors on apple canopy spectral characteristics and explore standardized spectral detection methods for apple florescence canopy. The results indicated the regularity in spectral reflectance of apple florescence canopy to a certain degree under different conditions, especially in the 760-1 350 nm near-infrared bands. The authors found that canopy spectral reflectance declined along with the decrease in sunshine and it is appropriate to detect canopy spectrum in sunny days with few clouds. In addition, spectral reflectance tended to be stable when the wind scale was below grade 2. The discrepancy of canopy spectra is small during the time period from 10:00 to 15:00 of a day compared to that of other times. For maintaining stable spectral curves, the height of detector to apple canopy needed to be adjusted to cover the whole canopy within the field of view according to detection angle of the detector. The vertical or approximately vertical detection was the best for canopy spectral reflectance acquisition. The standardization of technical methods of spectral detection for apple florescence canopy was proposed accordingly, which provided theoretical references for spectral detection and information extraction of apple tree canopy.
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[Hyperspectrum based prediction model for nitrogen content of apple flowers].
Guang Pu Xue Yu Guang Pu Fen Xi
PUBLISHED: 04-14-2010
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The present paper aims to quantitatively retrieve nitrogen content in apple flowers, so as to provide an important basis for apple informationization management. By using ASD FieldSpec 3 field spectrometer, hyperspectral reflectivity of 120 apple flower samples in full-bloom stage was measured and their nitrogen contents were analyzed. Based on the apple flower original spectrum and first derivative spectral characteristics, correlation analysis was carried out between apple flowers original spectrum and first derivative spectrum reflectivity and nitrogen contents, so as to determine the sensitive bands. Based on characteristic spectral parameters, prediction models were built, optimized and tested. The results indicated that the nitrogen content of apple was very significantly negatively correlated with the original spectral reflectance in the 374-696, 1 340-1 890 and 2 052-2 433 nm, while in 736-913 nm they were very significantly positively correlated; the first derivative spectrum in 637-675 nm was very significantly negatively correlated, and in 676-746 nm was very significantly positively correlated. All the six spectral parameters established were significantly correlated with the nitrogen content of apple flowers. Through further comparison and selection, the prediction models built with original spectral reflectance of 640 and 676 nm were determined as the best for nitrogen content prediction of apple flowers. The test results showed that the coefficients of determination (R2) of the two models were 0.825 8 and 0.893 6, the total root mean square errors (RMSE) were 0.732 and 0.638 6, and the slopes were 0.836 1 and 1.019 2 respectively. Therefore the models produced desired results for nitrogen content prediction of apple flowers with average prediction accuracy of 92.9% and 94.0%. This study will provide theoretical basis and technical support for rapid apple flower nitrogen content prediction and nutrition diagnosis.
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[Study on hyperspectral characteristics of apple florescence canopy].
Guang Pu Xue Yu Guang Pu Fen Xi
PUBLISHED: 12-30-2009
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The present study aims to systematically analyze the hyperspectral characteristics of apple florescence canopy and explore the sensitive spectra to provide the theoretical basis for large area apple information extracting and remote sensing retrieval for nutrition diagnosis. Based on the 120 hyperspectral data of apple florescence canopy acquired with ASD Field Spec 3 portable object spectrometer, the effects of different sample numbers on hyperspectral characteristics were analyzed. Using variance analysis method, the hyperspectral characteristics of apple florescence canopy and the sensitive wave bands were obtained. The results showed that with the increase in cumulative sample numbers, the hyperspectrum curves of apple florescence became stable and smooth. At the 550 nm green peak and the 760-1,300 nm reflection plateau, the reflection rate reduced with the increase in flowering amount, while in the red valley of 670 nm, the reflection rate increased with the increase in flowering amount; At the wave bands of 350-500, 600-680 and 760-1,300 nm, the variance analysis results showed very significant differences, indicating that they were sensitive wave bands of florescence canopy. With the increase in flowering amount, the red-edge position, the red-edge slope and red edge area tended to decrease gradually.
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A magnetically tunable colloidal crystal film for reflective display.
Macromol Rapid Commun
PUBLISHED: 06-04-2009
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A general approach to fabricate a magnetic field responsive colloidal crystal film has been developed. This is carried out by depositing monodisperse Fe(3) O(4) /PS composite magnetic nanospheres on the surface of an agarose-gel coated substrate. The optical properties of the resultant film can be easily controlled by an external magnetic field, which is caused by assembly of the magnetic nanospheres and alteration of the interparticle distance. With the help of a designed array of small magnets, both the color and pattern of the film can be conveniently modulated and the tuning range covers almost the whole visible spectrum. This work will be important for the potential application of monodisperse magnetic nanospheres in fabricating novel sensors, displays and optoelectronic devices.
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Colloidal crystal beads composed of core-shell particles for multiplex bioassay.
J Nanosci Nanotechnol
PUBLISHED: 05-15-2009
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A convenient method was developed to fabricate colloidal crystal beads (CCBs) with tough mechanical strength, which was used as encoded carriers for multiplex bioassay. The latex particles used for the construction of the CCBs were designed with a rigid core PS and a elastomeric shell poly(MMA/EA/MAA), and were prepared via one-step soap-free emulsion polymerization. The as-above-prepared CCBs were thermo-treated to drive the elastomeric shells of adjacent latex particles joining together. It was found that the coalescence of latex particles can greatly improve the mechanical strength of the CCBs for multiplex bioassay.
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[Monitoring models for phosphorus content of apple flowers based on hyperspectrum].
Ying Yong Sheng Tai Xue Bao
PUBLISHED: 04-20-2009
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By using ASD FieldSpec 3 field spectrometer, the hyperspectral reflectance of apple flowers at full-blooming stage was measured under laboratory conditions, and the correlations of the hyperspectral reflectance with the phosphorus content of apple flowers were analyzed based on the original spectrum and the first derivative spectral characteristics of the flowers. The sensitive wavebands were determined, the characteristic spectral parameters were constructed, and the monitoring models for the phosphorus content of apple flowers were established accordingly. Correlation analysis showed that the phosphorus content of apple flowers was significantly positively correlated with the original spectral reflectance at 350-370 nm, 670-1385 nm, and 1620-1760 nm, and the first derivative reflectance at 500-520 nm, and significantly negatively correlated with the first derivative reflectance at 670-730 nm. The spectral parameters DVI (936, 676), DVI (977, 676), NDVI (936, 676) and NDVI (977, 676) had close correlations with the phosphorus content of apple flowers, the correlation coefficients being all > 0.77. By using these spectral parameters as independent variables, four monitoring models for the phosphorus content of apple flowers were established, among which, the model with NDVI (936, 676) as the variable was validated as the best monitoring model, its determination coefficient was the highest (R2 = 0.9385), root mean square error and relative error were the smallest (RMSE = 0.6883, and RE = 7.6%), and prediction accuracy reached 92.4%.
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[Remote sensing techniques of apple orchard information extraction based on linear spectral unmixing with measured data].
Ying Yong Sheng Tai Xue Bao
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Taking Qixia City, Shandong Province of China as the research region, and by using pixel unmixing for the TM image at apple flowering stage, the apple orchard information was extracted. Based on the measured spectral end-members, wavelet transform was adopted to improve the linear unmixing model. The improved linear spectral unmixing model, measured end-member based linear spectral unmixing model, and TM image end-member based linear spectral unmixing model were employed to extract the apple orchard information, and the ALOS data were used for accuracy estimation. After the accurate atmospheric and topographic correction, it was feasible to use the measured spectral end-members for pixel unmixing, and the area precision of apple orchard information acquisition was greater than 97%. The regression analysis on the NDVI of abundance image and the average NDVI of ALOS data showed that the R2 was higher than 0.8. Therefore, using wavelet transform to improve the linear spectral unmixing model could improve the unmixing accuracy to a certain degree.
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Facile synthesis of gold wavy nanowires and investigation of their growth mechanism.
J. Am. Chem. Soc.
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We describe a synthesis of Au wavy nanowires in an aqueous solution in the presence of cetyltrimethylammonium bromide (CTAB). The resultant Au nanowires automatically separated from the solution and floated at the air/water interface. We investigated the formation mechanism by characterizing the samples obtained at different stages of the synthesis. Both particle attachment and cold welding were found to be involved in the formation of such nanowires. Based on X-ray photoelectron spectroscopy and thermogravimetric analysis, the CTAB molecules adsorbed on the surface of a Au nanostructure went through a change in structure from a bilayer to a monolayer, converting the Au surface from hydrophilic to hydrophobic. As a result, the Au wavy nanowires were driven to the air/water interface during the synthesis. This growth mechanism is potentially extendable to many other systems involving small surfactant molecules.
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[Quantitative remote sensing retrieval of apple tree canopy reflectance at blossom stage in hilly area].
Ying Yong Sheng Tai Xue Bao
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By using the TM and ALOS images with different resolutions at the prosperous blossom stage of apple trees in Qixia City of Shandong Province, and taking the slope aspect coefficient and the ratio of canopy flower to leaf into account, the ground surface reflectance was retrieved through radiometric correction. The canopy reflectance of the apple trees was further retrieved by pixel unmixing method, and the retrieval effect and accuracy were assessed by the comparison of the retrieved reflectance with the measured canopy reflectance and apparent reflectance of 30 sample apple orchards. The results showed that radiometric correction effectively weakened the effects of atmosphere and topography, recovered the ground objects in the shadows, and obviously enhanced the analytical ability of ground surface retrieval reflectance images. Either TM or ALOS images, both the absolute and relative errors between retrieval reflectance and measured reflectance of apple tree canopy were the smallest. The relative errors of all bands were consistent, and its variation trend among the 30 sample apple orchards was also consistent with the measured reflectance, which showed the necessary of pixel unmixing. Moreover, the changes of the reflectance among the sample apple orchards showed similar characteristics when the retrieval method was used for different resolution images. The images with high resolution were more superior, but, because of band limitation, it would be better to integrate the high resolution images with moderate resolution images.
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Observation of the fluorescence spectrum for a driven cascade model system in atomic beam.
Opt Express
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We experimentally study the resonance fluorescence from an excited two-level atom when the atomic upper level is coupled by a nonresonant field to a higher-lying state in a rubidium atomic beam. The heights, widths and positions of the fluorescence peaks can be controlled by modifying the detuning of the auxiliary field. We explain the observed spectrum with the transition properties of the dressed states generated by the coupling of the two laser fields. We also attribute the line narrowing to the effects of Spontaneously Generated Coherence between the close-lying levels in the dressed state picture generated by the auxiliary field. And the corresponding spectrum can be viewed as the evidence of Spontaneously Generated Coherence. The experimental results agree well with calculations based on the density-matrix equations.
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Kinetically controlled overgrowth of Ag or Au on Pd nanocrystal seeds: from hybrid dimers to nonconcentric and concentric bimetallic nanocrystals.
J. Am. Chem. Soc.
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This article describes a systematic study of the nucleation and growth of Ag (and Au) on Pd nanocrystal seeds. By carefully controlling the reaction kinetics, the newly formed Ag atoms could be directed to selectively nucleate and then epitaxially grow on a specific number (ranging from one to six) of the six faces on a cubic Pd seed, leading to the formation of bimetallic nanocrystals with a variety of different structures. In addition to changing the injection rate of precursor, we also systematically investigated other reaction parameters including the capping agent, reductant, and reaction temperature. Our results suggest that the site-selective growth of Ag on cubic Pd seeds could be readily realized by optimizing these reaction parameters. On the basis of the positions of Pd seeds inside the bimetallic nanocrystals as revealed by TEM imaging and elemental mapping, we could identify the exact growth pathways and achieve a clear and thorough understanding of the mechanisms. We have successfully applied the same strategy based on kinetic control to cubic Pd seeds with different sizes and octahedral Pd seeds of one size to generate an array of novel bimetallic nanocrystals with well-controlled structures. With cubic Pd seeds as an example, we have also extended this strategy to the Pd-Au system. We believe this work will provide a promising route to the fabrication of bimetallic nanocrystals with novel structures and properties for applications in plasmonics, catalysis, and other areas.
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[Hyperspectral estimation models of chlorophyll content in apple leaves].
Guang Pu Xue Yu Guang Pu Fen Xi
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The present study chose the apple orchard of Shandong Agricultural University as the study area to explore the method of apple leaf chlorophyll content estimation by hyperspectral analysis technology. Through analyzing the characteristics of apple leaves hyperspectral curve, transforming the original spectral into first derivative, red edge position and leaf chlorophyll index (LCI) respectively, and making the correlation analysis and regression analysis of these variables with the chlorophyll content to establish the estimation models and test to select the high fitting precision models. Results showed that the fitting precision of the estimation model with variable of LCI and the estimation model with variable of the first derivative in the band of 521 and 523 nm was the highest. The coefficients of determination R2 were 0.845 and 0.839, the root mean square errors RMSE were 2.961 and 2.719, and the relative errors RE% were 4.71% and 4.70%, respectively. Therefore LCI and the first derivative are the important index for apple leaf chlorophyll content estimation. The models have positive significance to guide the production of apple cultivation.
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Bio-inspired variable structural color materials.
Chem Soc Rev
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Natural structural color materials, especially those that can undergo reversible changes, are attracting increasing interest in a wide variety of research fields. Inspired by the natural creatures, many elaborately nanostructured photonic materials with variable structural colors were developed. These materials have found important applications in switches, display devices, sensors, and so on. In this critical review, we will provide up-to-date research concerning the natural and bio-inspired photonic materials with variable structural colors. After introducing the variable structural colors in natural creatures, we will focus on the studies of artificial variable structural color photonic materials, including their bio-inspired designs, fabrications and applications. The prospects for the future development of these fantastic variable structural color materials will also be presented. We believe this review will promote the communications among biology, bionics, chemistry, optical physics, and material science (196 references).
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.