scholarly journals FTIR Photoacoustic and ATR Spectroscopies of Soils with Aggregate Size Fractionation by Dry Sieving

ACS Omega ◽  
2022 ◽  
Author(s):  
Petr K. Krivoshein ◽  
Dmitry S. Volkov ◽  
Olga B. Rogova ◽  
Mikhail A. Proskurnin
Keyword(s):  
Aggregate Size ◽  
Size Fractionation

Improvements of physical properties of degraded shallow organic soils by admixing organic overlays and mineral sublayers

1991 ◽  
Vol 71 (1) ◽  
pp. 101-117 ◽  
Author(s):  
H. Dinel ◽  
S. P. Mathur ◽  
M. Lévesque
Keyword(s):  
Soil Structure ◽  
Crop Yields ◽  
Organic Amendments ◽  
Aggregate Size ◽  
Organic Soils ◽  
Structure Stability ◽  
Size Fractionation ◽  
Physical Conditions ◽  
Soil Media ◽  
The Stability

Twenty-five soil media representing 13 subsoils and organic overlays, and their mixtures, that had been used in pot culture fallow, or for growing root, leafy vegetable and grass crops, were studied to determine if the benefits of organic amendments to crop yields in optimally watered and fertilized soils were due to improvements in soil physical conditions. The soils were subjected to particle and aggregate size fractionation; and the stability of the aggregates was determined. The results suggested that admixing of residual organic overlays improved the structure of all mineral subsoils, except perhaps an alluvial sand. Aggregation and stability of aggregates > 2 mm were improved, thus leading to improved aeration, root proliferation and to increases in crop yields. In addition, grass crops were shown to be more effective than root and leafy crops for improvement of the structure of the various soils. Key words: Organic soils, soil aggregation, soil structure stability

scholarly journals Role for Hsp70 Chaperone in Saccharomyces cerevisiae Prion Seed Replication

2005 ◽  
Vol 4 (2) ◽  
pp. 289-297 ◽  
Author(s):  
Youtao Song ◽  
Yue-xuan Wu ◽  
Giman Jung ◽  
Yusuf Tutar ◽  
Evan Eisenberg ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fluorescence Recovery After Photobleaching ◽  
Fluorescent Protein ◽  
Sodium Dodecyl ◽  
Aggregate Size ◽  
Limited Capacity ◽  
Size Fractionation ◽  
Hsp70 Chaperone ◽  
Green Fluorescent ◽  
Insoluble Polymers

ABSTRACT The Saccharomyces cerevisiae [PSI + ] prion is a misfolded form of Sup35p that propagates as self-replicating cytoplasmic aggregates. Replication is believed to occur through breakage of transmissible [PSI + ] prion particles, or seeds, into more numerous pieces. In [PSI + ] cells, large Sup35p aggregates are formed by coalescence of smaller sodium dodecyl sulfate-insoluble polymers. It is uncertain if polymers or higher-order aggregates or both act as prion seeds. A mutant Hsp70 chaperone, Ssa1-21p, reduces the number of transmissible [PSI + ] seeds per cell by 10-fold but the overall amount of aggregated Sup35p by only two- to threefold. This discrepancy could be explained if, in SSA1-21 cells, [PSI + ] seeds are larger or more of the aggregated Sup35p does not function as a seed. To visualize differences in aggregate size, we constructed a Sup35-green fluorescent protein (GFP) fusion (NGMC) that has normal Sup35p function and can propagate like [PSI + ]. Unlike GFP fusions lacking Sup35p's essential C-terminal domain, NGMC did not form fluorescent foci in log-phase [PSI + ] cells. However, using fluorescence recovery after photobleaching and size fractionation techniques, we find evidence that NGMC is aggregated in these cells. Furthermore, the aggregates were larger in SSA1-21 cells, but the size of NGMC polymers was unchanged. Possibly, NGMC aggregates are bigger in SSA1-21 cells because they contain more polymers. Our data suggest that Ssa1-21p interferes with disruption of large Sup35p aggregates, which lack or have limited capacity to function as seed, into polymers that function more efficiently as [PSI + ] seeds.

The Effect of Red Blood Cells on the ADP-induced Aggregation of Human Platelets in Flow Through Tubes

1990 ◽  
Vol 63 (01) ◽  
pp. 112-121 ◽  
Author(s):  
David N Bell ◽  
Samira Spain ◽  
Harry L Goldsmith
Keyword(s):  
Platelet Aggregation ◽  
Shear Rate ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Platelet Rich Plasma ◽  
Mean Transit Time ◽  
White Blood Cells ◽  
Aggregate Size ◽  
Human Platelets ◽  
Induced Aggregation

SummaryThe effect of red blood cells, rbc, and shear rate on the ADPinduced aggregation of platelets in whole blood, WB, flowing through polyethylene tubing was studied using a previously described technique (1). Effluent WB was collected into 0.5% glutaraldehyde and the red blood cells removed by centrifugation through Percoll. At 23°C the rate of single platelet aggregtion was upt to 9× greater in WB than previously found in platelet-rich plasma (2) at mean tube shear rates Ḡ = 41.9,335, and 1,920 s−1, and at both 0.2 and 1.0 µM ADP. At 0.2 pM ADP, the rate of aggregation was greatest at Ḡ = 41.9 s−1 over the first 1.7 s mean transit time through the flow tube, t, but decreased steadily with time. At Ḡ ≥335 s−1 the rate of aggregation increased between t = 1.7 and 8.6 s; however, aggregate size decreased with increasing shear rate. At 1.0 µM ADP, the initial rate of single platelet aggregation was still highest at Ḡ = 41.9 s1 where large aggregates up to several millimeters in diameter containing rbc formed by t = 43 s. At this ADP concentration, aggregate size was still limited at Ḡ ≥335 s−1 but the rate of single platelet aggregation was markedly greater than at 0.2 pM ADP. By t = 43 s, no single platelets remained and rbc were not incorporated into aggregates. Although aggregate size increased slowly, large aggregates eventually formed. White blood cells were not significantly incorporated into aggregates at any shear rate or ADP concentration. Since the present technique did not induce platelet thromboxane A2 formation or cause cell lysis, these experiments provide evidence for a purely mechanical effect of rbc in augmenting platelet aggregation in WB.

A Hybrid Model to Predict the Gyratory Compaction of Hot Mixed Asphalt

2019 ◽  
Author(s):  
Teng Man
Keyword(s):  
Hybrid Model ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Aggregate Size ◽  
Asphalt Mixtures ◽  
Compaction Process ◽  
Particle Rearrangement ◽  
Compaction Behavior ◽  
Grain Size Distributions ◽  
Gyratory Compaction

The compaction of asphalt mixture is crucial to the mechanical properties and the maintenance of the pavement. However, the mix design, which based on the compaction properties, remains largely on empirical data. We found difficulties to relate the aggregate size distribution and the asphalt binder properties to the compaction behavior in both the field and laboratory compaction of asphalt mixtures. In this paper, we would like to propose a simple hybrid model to predict the compaction of asphalt mixtures. In this model, we divided the compaction process into two mechanisms: (i) visco-plastic deformation of an ordered thickly-coated granular assembly, and (ii) the transition from an ordered system to a disordered system due to particle rearrangement. This model could take into account both the viscous properties of the asphalt binder and grain size distributions of the aggregates. Additionally, we suggest to use the discrete element method to understand the particle rearrangement during the compaction process. This model is calibrated based on the SuperPave gyratory compaction tests in the pavement lab. In the end, we compared the model results to experimental data to show that this model prediction had a good agreement with the experiments, thus, had great potentials to be implemented to improve the design of asphalt mixtures.

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