Accurate long-term shoreline change rates are required for a wide range of shoreline studies and coastal zone management applications in the Great Lakes Basin. However, the literature on methods, ...techniques for quantifying source errors, guidelines for data acquisition, and new approaches is focused primarily on the sandy coastlines of the eastern and gulf coasts of the United States. Therefore, a comprehensive shoreline change investigation was completed for Ottawa and Allegan Counties, Michigan to investigate issues specific to the fresh water shorelines of the Great Lakes. A detailed spatial database was developed that included 79 km of continuous top of bank and dune crest lines for five temporal periods. Over 70,000 erosion transects were generated and analyzed with customized ArcGIS tools for the sandy and cohesive shore types found in the two counties. Significant spatial and temporal variability in the transect measurements were observed for both shore types. Based on the results, a series of detailed recommendations are provided for selecting historical sources of positional data, minimizing sampling errors by selecting an appropriate transect spacing, considering lake level impacts, and the influence of the bluff failure cycle on recession rates.
Electrophilic trisubstituted ethylenes, halogen ring-substituted methyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO
2
CH
3
(where R is 3-Br-4-CH
3
O, 5-Br-2-CH
3
O, 2-F-5-CH
3
, 2-F-6-CH
3
, ...4-F-3-CH
3
, 4-F-3-PhO, 2-F-5-I, 2-F-6-I, 2-F
3
C, 4-F
3
C) were prepared and copolymerized with styrene. The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and methyl cyanoacetate, and characterized by CHN analysis, IR,
1
H and
13
C-NMR. All the ethylenes were copolymerized with styrene (M
1
) in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR,
1
H and
13
C-NMR. The order of relative reactivity (1/r
1
) for the monomers is 2-F-5-CH
3
(6.4) > 4-F-3-PhO (5.6) > 4-F
3
C (4.8) > 3-Br-4-CH
3
O (3.7) > 2-F-5-I (3.6) > 2-F
3
C (2.2) > 2-F-6-I (2.1) > 5-Br-2-CH
3
O (1.9) > 4-F-3-CH
3
(1.8) > 2-F-6-CH
3
(1.2). Relatively high T
g
of the copolymers in comparison with that of polystyrene indicates a decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200-500°C range with residue (2-21% wt), which then decomposed in the 500-800°C range.
The epithelial Na+ channel (ENaC) is assembled from three homologous subunits, two of which are cleaved resulting in the release of inhibitory tracts and channel activation. Peptides corresponding to ...these tracts are inhibitory. Mutagenesis and double mutant cycle data implicated sites in the finger‐thumb domain interface in the periphery of the α subunit in inhibitory peptide binding. We built a model of the α subunit of ENaC based on these data and on homology to ASIC1, which predicts specific sites that are in close proximity to the bound inhibitory peptide. We examined whether introducing Cys at specific sites in the channel and peptide would allow for crosslinking with bifunctional Cys reactive crosslinkers resulting in an inhibition of channel activity. Peptide‐channel crosslinking was dependent on the sites of the introduced Cys, and in most cases on the length of the crosslinker. We also found that a crosslink between specific sites in the finger and thumb domains of the α subunit reduced channel activity, suggesting that these sites move relative to one another during gating. The observed effect was dependent on crosslinker length.
Two Sm-Fe-based alloys, with compositions Sm/sub 13.7/--Fe/sub 86.3/ and Sm/sub 13.8/--Fe/sub 82.2/--Ta/sub 4.0/, were investigated in order to determine their disproportionation reaction kinetics. ...The alloys were first heated in hydrogen at a rate of 4/spl deg/C/min to a temperature where the disproportionation reaction starts. At this onset temperature, which is different for the individual material, the alloy begins to decompose into a rare-earth hydride and /spl alpha/Fe. The disproportionation behavior of the systems can be explained in terms of the Johnson-Mehl-Avrami (JMA) theory of phase transformations. The ternary alloy with Ta satisfies the JMA conditions and has Avrami constants of /spl les/0.5, which implies diffusion-controlled one-dimensional growth, i.e., the thickening of particles with an appreciable initial volume. On the other hand, the growth of a newly formed iron phase in the binary alloy can only be explained in terms of mixed-transformation process involving one-dimensional and two-dimensional growth.
A clear understanding of the reactions and phase changes that occur during the processing of a material is vital if we want to be able to achieve the best properties. In this series of experiments, ...we have used a vibrating-sample magnetometer (VSM) to monitor the magnetic state of compacted powder samples of Sm
13.7Fe
86.3 and Sm
13.8Fe
82.2Ta
4.0 during a standard hydrogenation–disproportionation–desorption–recombination (HDDR) cycle. The samples were mounted in the VSM and heated at 4°C/min in 1
bar of flowing hydrogen to 750°C, they were then held for 60
min under hydrogen and approximately 120
min under vacuum before being cooled to room temperature under vacuum at 4°C/min. The results show that the initial absorption of hydrogen by the Sm
2Fe
17-type phase results in an increase in magnetization as well as
T
C. At higher temperatures, the disproportionation reactions of the Sm
13.7Fe
86.3 and Sm
13.8Fe
82.2Ta
4.0 materials were observed to proceed at a faster rate for the second and third cycles of the HDDR procedure than for the first. The results are in agreement with our previous transmission electron microscopy studies, which showed that much of the Ta that was initially dissolved in the Sm
2Fe
17-type phase of the cast Sm
13.8Fe
82.2Ta
4.0 material was reformed as Ta-based precipitates after a single HDDR cycle leaving the Sm
2Fe
17-type phase with much less dissolved Ta.
PDF
