THE OPPOSITION TO THE KILGORE BILL     

Dunn LC 《Science (New York, N.Y.)》1943,97(2527):510-511

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Probing single molecule dynamics     

Xie XS  Dunn RC 《Science (New York, N.Y.)》1994,265(5170):361-364

The room temperature dynamics of single sulforhodamine 101 molecules dispersed on a glass surface are investigated on two different time scales with near-field optics. On the 10(-2)- to 10(2)-second time scale, intensity fluctuations in the emission from single molecules are examined with polarization measurements, providing insight into their spectroscopic properties. On the nanosecond time scale, the fluorescence lifetimes of single molecules are measured, and their excited-state energy transfer to the aluminum coating of the near-field probe is characterized. A movie of the time-resolved emission demonstrates the feasibility of fluorescence lifetime imaging with single molecule sensitivity, picosecond temporal resolution, and a spatial resolving power beyond the diffraction limit.  相似文献   

Molecular dissection of transcriptional control elements within the long terminal repeat of the retrovirus   总被引：7，自引：0，他引：7  

A Srinivasan  E P Reddy  C Y Dunn  S A Aaronson 《Science (New York, N.Y.)》1984,223(4633):286-289

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Chitin in sea anemone shells     

Dunn DF  Liberman MH 《Science (New York, N.Y.)》1983,221(4606):157-159

Chitin, which is widely distributed among life forms, is well documented in the coelenterate class Hydrozoa and is contained in one member of class Scyphozoa. In class Anthozoa, hard corals synthesize it but soft corals do not. Chitin was identified by infrared spectrophotometry in the trochoid shell of the actinian Stylobates. It constitutes 1.7 percent of the shell by weight, the rest probably being protein. The ability of sea anemones to synthesize chitin is there by confirmed.  相似文献   

Photosynthetic light use efficiency of three biomes across an east–west continental-scale transect in Canada     

Christopher R. Schwalm  T. Andrew Black  Brian D. Amiro  M. Altaf Arain  Alan G. Barr  Charles P.-A. Bourque  Allison L. Dunn  Larry B. Flanagan  Marc-Andr Giasson  Peter M. Lafleur  Hank A. Margolis  J. Harry McCaughey  Alberto L. Orchansky  Steve C. Wofsy 《Agricultural and Forest Meteorology》2006,140(1-4):269

Light use efficiency (LUE) is used widely in scaling and modeling contexts. However, the variation and biophysical controls on LUE remain poorly documented. Networks of eddy covariance (EC) towers offer an opportunity to quantify _g, the ratio of P, gross primary productivity, to Q_a, absorbed photosynthetically active radiation (PAR), across climate zones and vegetation types. Using data from the Fluxnet Canada Research Network (n = 24 sites) in 2004, we examined the relationship between daily and yearly _g, driving variables, and site characteristics on a site-specific and plant functional type (PFT) basis using tree regression and linear regression. Data were available for three biomes: grassland, forest, and wetland. Yearly _g values ranged from 0.1 to 3.6 g C MJ⁻¹ Q_a overall. Daily _g was highest in the grassland (daily median ± interquartile range: 3.68 ± 1.98 g C MJ⁻¹ Q_a), intermediate in the forested biome (0.84 ± 0.82 g C MJ⁻¹ Q_a), and lowest for the wetlands (0.65 ± 0.54 g C MJ⁻¹ Q_a). The most important biophysical controls were light and temperature, to the exclusion of water-related variables: a homogeneity of slopes model explained c. 75% of the variation in daily _g. For a subset of sites with diffuse PAR data, the ratio of diffuse to total PAR, a proxy for cloudiness, was a key predictor. On the yearly time scale, _g was related to leaf area index and mean annual temperature. Aggregating to PFTs did not show functional convergence within any PFT except for the three wetland sites and the Picea mariana toposequence at the daily time step, and when using the Köppen climate classification on a yearly time step. The general lack of conservative daily _g behavior within PFTs suggests that PFT-based parameterizations are inappropriate, especially when applied on shorter temporal scales.  相似文献   

Acute‐Phase Proteins and Iron Status in Cats with Chronic Kidney Disease          下载免费PDF全文

R. Javard  C. Grimes  L. Bau‐Gaudreault  M. Dunn 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2017,31(2):457-464

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Stability of Native Folate and Added Folic Acid in Micronutrient‐Fortified Corn Masa and Tortillas     

J. S. Chapman  F. M. Steele  D. L. Eggett  N. P. Johnston  M. L. Dunn 《Cereal Chemistry》2010,87(5):434-438

Degradation of added folic acid and native folates in micronutrient‐fortified corn masa and tortillas was evaluated using masa prepared from either nixtamalized corn flour or fresh nixtamal. Variations in masa pH, masa holding time at an elevated temperature, and iron source failed to show significant differences in folate loss in corn flour masa prepared in the laboratory. Masa was subsequently prepared from fresh nixtamal in a commercial mill in Mexico, and fortified with one of two different micronutrient premixes containing iron, zinc, B‐vitamins, and either unencapsulated or lipid‐encapsulated folic acid. Folate loss in commercial masa increased significantly with prebake masa holding time for both premixes. Unencapsulated folic acid showed a 73% loss after 4 hr of holding, compared to 60% loss for encapsulated. The difference was statistically significant, indicating a protective effect from the lipid coating. No significant differences in folate levels were found between prebake masa and baked tortillas. Holding baked tortillas for up to 12 hr also had no effect on folate levels. Native folate showed no significant losses throughout the process. Results from the commercial tortilla mill indicate that most of the loss in added folic acid occurs during prebake holding of masa, possibly from microbial degradation.  相似文献