A Synthetic Mimic of Protein Inner Space:  Buried Polar Interactions in a Deep Water-Soluble Host

2006 ◽  
Vol 128 (48) ◽  
pp. 15366-15367 ◽  
Author(s):  
Sara M. Butterfield ◽  
Julius Rebek
2020 ◽  
Vol 71 (2) ◽  
pp. 190
Author(s):  
M. E. Manzur ◽  
A. A. Grimoldi ◽  
G. G. Striker

Grazing, flooding and their combination are major disturbances that could affect plant performance in humid grasslands. We performed two experiments to study the tolerance of the forage grass Paspalum dilatatum Poir. to different submergence depths and defoliation frequencies. First, we addressed whether this species can shift from the escape strategy to ‘quiescence’ when completely submerged for 30 days. Second, we explored to what extent partial or complete submergence produced by defoliation compromises plant regrowth. The results showed that regardless of the depth of water at submergence, P. dilatatum always responded by attempting to expose its leaf area above water, by increasing the tiller angle and/or blade length (i.e. tiller height). Partially submerged plants showed a reduction in starch concentration (89%) but biomass was unaffected, whereas completely submerged plants did not survive. After one defoliation event, 77% of aerial biomass of partially submerged plants was removed and the concentration of carbon reserves (water-soluble carbohydrates and starch) decreased to half that of control plants. A second event of defoliation (20 days later) of plants with few reserves removed 50–52% of shoot biomass and compromised plant survival, with plants dying before the end of the experiment. In conclusion, P. dilatatum does not tolerate prolonged conditions of complete submergence caused by either deep water columns or repeated defoliation.


2006 ◽  
Vol 118 (21) ◽  
pp. 3597-3599 ◽  
Author(s):  
Richard J. Hooley ◽  
Shannon M. Biros ◽  
Julius Rebek

2013 ◽  
Vol 318 ◽  
pp. 507-512 ◽  
Author(s):  
Qian Sheng Yue ◽  
Qing Zhi Yang ◽  
Shu Jie Liu ◽  
Bao Sheng He ◽  
You Lin Hu

The rheological property of the drilling fluid was one of the focus problems in deep-water drilling, which was widely concerned. In the article, the viscosity-temperature properties of commonly used water soluble polymeric solution, polymeric brine solution, bentonite slurry, polyacrylamide-potassium chloride drilling fluid with different densities and water-base drilling fluid systems commonly used for China offshore well drillings were studied. 4°C-to-20°C viscosity ratio and 4°C-to-20°C YP ratio were used to judge the thickening level of drilling fluids due to low temperature. The experimental results show that on the condition of without considering the influence of pressure on the rheological property of water-base drilling fluid, its viscosity and yield point raised obviously with the decrease of temperature, but the increase level is proximately the same, its 4°C-to-20°C apparent viscosity ratio is basically within the 1.50. Analysis indicates that the viscosity of water-base drilling fluid depends on the viscosity of dispersed media. The performance of water medium determines the viscosity-temperature property of the water-based drilling fluid. It is proposed that in deep water drillings, if a water-base drilling fluid is used, it is not necessary to emphasize the influence of deep water and low temperature on the flowability. On the condition of guaranteeing wellbore stability and borehole cleaning, it is more suitable for using the water-base drilling fluid with low viscosity and low gel strength for deep water well drillings.


2006 ◽  
Vol 45 (21) ◽  
pp. 3517-3519 ◽  
Author(s):  
Richard J. Hooley ◽  
Shannon M. Biros ◽  
Julius Rebek

2014 ◽  
Vol 50 (38) ◽  
pp. 4895-4897 ◽  
Author(s):  
Kang-Da Zhang ◽  
Dariush Ajami ◽  
Jesse V. Gavette ◽  
Julius Rebek

A cavitand with ionic, but nonionizable “feet” folds around hydrophobic guests in D2O.


2017 ◽  
Vol 114 (38) ◽  
pp. 10065-10070 ◽  
Author(s):  
Jonas Gros ◽  
Scott A. Socolofsky ◽  
Anusha L. Dissanayake ◽  
Inok Jun ◽  
Lin Zhao ◽  
...  

During theDeepwater Horizondisaster, a substantial fraction of the 600,000–900,000 tons of released petroleum liquid and natural gas became entrapped below the sea surface, but the quantity entrapped and the sequestration mechanisms have remained unclear. We modeled the buoyant jet of petroleum liquid droplets, gas bubbles, and entrained seawater, using 279 simulated chemical components, for a representative day (June 8, 2010) of the period after the sunken platform’s riser pipe was pared at the wellhead (June 4–July 15). The model predicts that 27% of the released mass of petroleum fluids dissolved into the sea during ascent from the pared wellhead (1,505 m depth) to the sea surface, thereby matching observed volatile organic compound (VOC) emissions to the atmosphere. Based on combined results from model simulation and water column measurements, 24% of released petroleum fluid mass became channeled into a stable deep-water intrusion at 900- to 1,300-m depth, as aqueously dissolved compounds (∼23%) and suspended petroleum liquid microdroplets (∼0.8%). Dispersant injection at the wellhead decreased the median initial diameters of simulated petroleum liquid droplets and gas bubbles by 3.2-fold and 3.4-fold, respectively, which increased dissolution of ascending petroleum fluids by 25%. Faster dissolution increased the simulated flows of water-soluble compounds into biologically sparse deep water by 55%, while decreasing the flows of several harmful compounds into biologically rich surface water. Dispersant injection also decreased the simulated emissions of VOCs to the atmosphere by 28%, including a 2,000-fold decrease in emissions of benzene, which lowered health risks for response workers.


2006 ◽  
pp. 509-510 ◽  
Author(s):  
Richard J. Hooley ◽  
Shannon M. Biros ◽  
Julius Rebek, Jr.
Keyword(s):  

1988 ◽  
Vol 62 (01) ◽  
pp. 1-8 ◽  
Author(s):  
Ronald E. Martin

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.


Author(s):  
J. G. Robertson ◽  
D. F. Parsons

The extraction of lipids from tissues during fixation and embedding for electron microscopy is widely recognized as a source of possible artifact, especially at the membrane level of cell organization. Lipid extraction is also a major disadvantage in electron microscope autoradiography of radioactive lipids, as in studies of the uptake of radioactive fatty acids by intestinal slices. Retention of lipids by fixation with osmium tetroxide is generally limited to glycolipids, phospholipids and highly unsaturated neutral lipids. Saturated neutral lipids and sterols tend to be easily extracted by organic dehydrating reagents prior to embedding. Retention of the more saturated lipids in embedded tissue might be achieved by developing new cross-linking reagents, by the use of highly water soluble embedding materials or by working at very low temperatures.


Author(s):  
J. D. McLean ◽  
S. J. Singer

The successful application of ferritin labeled antibodies (F-A) to ultrathin sections of biological material has been hampered by two main difficulties. Firstly the normally used procedures for the preparation of material for thin sectioning often result in a loss of antigenicity. Secondly the polymers employed for embedding may non-specifically absorb the F-A. Our earlier use of cross-linked polyampholytes as embedding media partially overcame these problems. However the water-soluble monomers used for this method still extract many lipids from the material.


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