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  • 1
    Call number: ZSP-201-78/23
    In: CRREL Report, 78-23
    Type of Medium: Series available for loan
    Pages: vi, 53 S. : Ill.
    Series Statement: CRREL Report 78-23
    Note: CONTENTS Abstract Preface Nomenclature Conversion factors: Metric (SI) to U.S. customary unitsof measurement Introduction Selection of experimental approach Previous investigations of effect of freeze-thaw on soil deform ability Selection of laboratory test method Selection of method of field validation tests Field repeated-load plate-bearing tests Test pavements, soils and materials Test procedures and results Resilient modulus of subgrade calculated from field tests Mathematical model Characterization of asphalt concrete Characterization of frozen silt Calculated resilient modulus of silt within the zone of freezing Laboratory repeated-load triaxial tests Specimens, equipment and testing procedures Apparatus Procedures Resilient properties calculated from laboratory tests Calculation methods Asphalt concrete — test results Asphalt concrete — statistical analysis and discussion Silt — test results Silt — statistical analysis Discussion and conclusions Literature cited Appendix A. Repeated-load plate-bearing test results Appendix B. Laboratory repeated-load triaxial test results Appendix C. Regression equation coefficients for resilient modulus and Poisson’s ratio from repeated-load triaxial test data on asphalt concrete and s ilt Appendix D. Detailed procedures for repeated-load triaxial testing ILLUSTRATIONS Figure Test pavements Properties of silt Aggregates for asphalt concrete Repeated-load plate-bearing test apparatus Load pulse waveforms Ground temperatures at test point P1 Resilient deflection of plate and two radial points, test point P1 Stiffness modulus of asphalt concrete used in analysis Resilient modulus of frozen silt used in analysis
    Location: AWI Archive
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  • 2
    Call number: ZSP-201-80/10
    In: CRREL Report, 80-10
    Description / Table of Contents: A mathematical model of coupled heat and moisture flow in soils has been developed. The model includes algorithms for phase change of soil moisture and frost heave and permits several types of boundary and initial conditions. The finite element method of weighted residual (Galerkin procedure) was chosen to simulate the spatial regime and the Crank-Nicholson method was used for the time domain portion of the model. To facilitate evaluation of the model, the heat and moisture fluxes were essentially decoupled; moisture flux was then simulated accurately, as were heat flux and frost heave in a laboratory test. Comparison of the simulated and experimental data illustrates the importance of unsaturated hydraulic conductivity. It is one parameter which is difficult to measure and for which only a few laboratory test results are available. Therefore, unsaturated hydraulic conductivities calculated in the computer model may be a significant source of error in calculations of frost heave. The algorithm incorporating effects of surcharge and overburden was inconclusively evaluated. Time-dependent frost penetration and frost heave in laboratory specimens were closely simulated with the model. After 10 days of simulation, the computed frost heave was about 2.3 cm vs 2.0 cm and 2.8 cm in two tests. Frost penetration was computed as 15 cm and was measured at 12.0 cm and 12.2 cm in the two laboratory samples after 10 days.
    Type of Medium: Series available for loan
    Pages: v, 49 Seiten , Illustrationen
    Series Statement: CRREL Report 80-10
    Language: English
    Note: CONTENTS Abstract Preface Introduction One-dimensional equations of simultaneous heat and moisture flux Moisture transport Heat transport Phase change Coupling effects Frost heave algorithm Development of computer model Finite difference vs finite element method Finite element formulation Time domain solution Evaluation of the mathematical model Heat flux Moisture flux Numerical dispersion Frost heave of homogeneous laboratory samples Conclusions Recommended studies to refine the model Literature cited Appendix A. Work plan, staffing and instrumentation requirements for correlating results oflaboratory frost susceptibility tests with field performance Appendix B. Proposed investigation of thaw weakening of subgrade soil and granular unboundbase course Appendix C. Derivation of finite element system matrices
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  • 3
    Call number: ZSP-201-80/5
    In: CRREL Report, 80-5
    Description / Table of Contents: This research comprised laboratory testing to determine the properties of asphalt-aggregate mixtures containing three grades of asphalt cements, and analyses to project the performance of pavements containing each of the asphalts, in resisting thermally induced distress and traffic-associated distress. From the results it is concluded that only the softest asphalt cement tested (AC 2.5) would perform satisfactorily in a cold climatic zone. The moderately soft (AC 5) and moderately hard (AC 20) asphalt cements showed little susceptibility to thermal cracking in a moderate and a warm climatic zone, respectively. The AC 2.5 and AC 5 asphalts are not recommended for use in warm climates, however, owing to increased susceptibility to rutting under traffic.
    Type of Medium: Series available for loan
    Pages: vi, 55 Seiten , Illustrationen
    Series Statement: CRREL Report 80-5
    Language: English
    Note: CONTENTS Abstract Preface Introduction Research setting Objectives Materials, mixture designs, and tests Materials Mixture design tests Brazil test Resilient modulus test Data analysis Marshall tests Asphalt grade Compactive effort Aggregate type Data analysis Brazil tests Indirect tensile strength Tensile strain Vertical deformation Summary of Brazil test results Data analysis-resilIient modulus. Comparison of mixture susceptibility to temperature cracking General asphalt concrete stiffness Thermal cracking. Influence of asphalt cement properties Summary Comparison of mixture susceptibility to traftic-load-associated distress Stress/strain analysis Fatigue damage analysis Rutting analysis Strength correlations Marshall stability and indirect tensile strength Indirect tensile strength and resilient modulus Summary Summary and conclusions Recapitulation of investigations Summary of results Conclusions Literature cited Appendix A: Asphalt adggregate mixture properties by Marshall method Appendix B: Equations for calculating specimen properties from Brazil tests Appendix C: Calculated displacements, strains and stresses
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  • 4
    ISSN: 1432-072X
    Keywords: Photosynthesis ; Regulation ; Thioredoxin ; Cyanobacterium ; Chromatium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Enzymes that are regulated by the ferredoxin/thioredoxin system in chloroplasts — fructose-1,6-bisphosphatase (FBPase), sedoheptulose-1,7-bisphosphatase purified from two different types of photosynthetic prokaryotes (cyanobacteria, purple sulfur bacteria) and tested for a response to thioredoxins. Each of the enzymes from the cyanobacterium Nostoc muscorum, an oxygenic organism known to contain the ferredoxin/thioredoxin system, was activated by thioredoxins that had been reduced either chemically by dithiothreitol or photochemically by reduced ferredoxin and ferredoxin-thioredoxin reductase. Like their chloroplast counterparts, N. muscorum FBPase and SBPase were activated preferentially by reduced thioredoxin f. SBPase was also partially activated by thioredoxin m. PRK, which was present in two regulatory forms in N. muscorum, was activated similarly by thioredoxins f and m. Despite sharing the capacity for regulation by thioredoxins, the cyanobacterial FBPase and SBPase target enzymes differed antigenically from their chloroplast counterparts. The corresponding enzymes from Chromatium vinosum, an anoxygenic photosynthetic purple bacterium found recently to contain the NADP/thioredoxin sytem, differed from both those of cyanobacteria and chloroplasts in showing no response to reduced thioredoxin. Instead, C. vinosum FBPase, SBPase, and PRK activities were regulated by a metabolite effector, 5′-AMP. The evidence is in accord with the conclusion that thioredoxins function in regulating the reductive pentose phosphate cycle in oxygenic prokaryotes (cyanobacteria) that contain the ferredoxin/thioredoxin system, but not in anoxygenic prokaryotes (photosynthetic purple bacteria) that contain the NADP/thioredoxin system. In organisms of the latter type, enzyme effectors seem to play a dominant role in regulating photosynthetic carbon dioxide assimilation.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0730-2312
    Keywords: growth regulation ; Sialoglycopeptide inhibitor ; protease protein synthesis inhibition ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have recently described the isolation and purification to homogeneity of a new Sialoglycopeptide from bovine brain cell surfaces that reversibly inhibits protein synthesis and DNA synthesis of normal but not transformed cells. Active inhibitory preparations, however, were shown to contain a protease activity that was not lost upon purification. Several experiments were performed to establish the relationship between the proteolytic activity of the Sialoglycopeptide and the biological inhibitory activity. Both the protease activity and inhibitory activity were stable at pH 6-8 but were reduced or completely destroyed below pH 4 and above pH 9. Acid inactivation was reversible and upon dialysis, both the biological inhibitory and protease activities were regained. Deglycosylation and CNBr cleavage indicated that the polypeptide backbone, rather than carbohydrate moiety, played an important role in the protease and biological inhibitory activities. Furthermore, chemical modification of amino and tyrosine groups indicated that both residues are essential for both activities. Thus, the biological inhibitory activity and protease activity are very closely related and most likely reside with the same polypeptide sequence.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5079
    Keywords: fructose-2,6-bisphosphate ; PFK ; PFP ; Chlorella ; green algae ; carbon metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell-free preparations from the green alga, Chlorella pyrenoidosa, contained two forms of phosphofructokinase (PFK), designated PFK I and PFK II. This represents the first evidence for a second form of PFK in green algae. A pyrophosphate D-fructose-6-phosphate, 1-phosphotransferase (PFP) activity, that was unaffected by the regulatory metabolite, fructose-2,6-bisphosphate, co-purified with PFK II through several steps. The data suggest that Chlorella pyrenoidosa resembles higher plants in containing two forms of PFK, but differs in containing an atypical form of PFP.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A sialoglycopeptide (SGP), isolated and purified from bovine cerebral cortex cells, was studied in regard to early signal transduction events associated with the cell cycle. Previously shown to be a potent antagonist to a variety of mitogens, the SGP abrogated the ability of 12-O-tetradecanoylphorbol-13 acetate (TPA) to elicit an alkalinization of 3T3 cell cytosol, but only when added minutes prior to, or simultaneously with, the tumor promoter. 3T3 cell TPA-mediated Ca2+ mobilization was also inhibited by the SGP although the inhibitor itself did not bind Ca2+ in a cell-free assay. The results are discussed in light of the already known kinetics of interaction between the SGP, various mitogens, and the calcium ionophore A23187 with regard to the pivotal events leading to the decision of a cell to divide or not to divide.
    Additional Material: 6 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    ISSN: 0084-6597
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 2018-06-06
    Description: Tidal currents and waves have caused some reworking and redistribution of Holocene sediments in the northern North Sea, with preferential deposition of fines in topographic depressions. This has led to a patchy distribution of sediments in terms of their textural, mineralogical and chemical composition. Nevertheless discernable relationships are found to exist between mean grain size and composition of the sediments. The relative abundance of biogenic components (primarily benthic Foraminifera) in the sand-size fraction of the sediments increases as mean grain size decreases, thus biogenic components are relatively more abundant in bathymetric lows. Coarse-grained sediments rich in detrital quartz show higher values of Si/ AI than do fine-grained sediments. Smectite is concentrated in the finest-grained sediments, whereas illite is relatively more abundant in coarser deposits. Thus clay mineral segregation processes previously reported to occur near river mouths also occur in an open shelf environment. Fine-grained, smectite-rich sediments show correspondingly higher values of Fe/ AI and lower values of K/ AI compared to the coarser deposits enriched in illite.
    Type: Article , NonPeerReviewed
    Format: text
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  • 10
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    In:  Other Sources
    Publication Date: 2011-08-24
    Description: Cell proliferation is governed by the influence of both mitogens and inhibitors. Although cell contact has long been thought to play a fundamental role in cell cycling regulation, and negative regulators have long been suspected to exist, their isolation and purification has been complicated by a variety of technical difficulties. Nevertheless, over recent years an ever-expanding list of putative negative regulators have emerged. In many cases, their biological inhibitory activities are consistent with density-dependent growth inhibition. Most likely their interactions with mitogenic agents, at an intracellular level, are responsible for either mitotic arrest or continued cell cycling. A review of naturally occurring cell growth inhibitors is presented with an emphasis on those factors shown to be residents of the cell surface membrane. Particular attention is focused on a cell surface sialoglycopeptide, isolated from intact bovine cerebral cortex cells, which has been shown to inhibit the proliferation of an unusually wide range of target cells. The glycopeptide arrest cells obtained from diverse species, both fibroblasts and epithelial cells, and a broad variety of transformed cells. Signal transduction events and a limited spectrum of cells that are refractory to the sialoglycopeptide have provided insight into the molecular events mediated by this cell surface inhibitor.
    Keywords: Life Sciences (General)
    Type: Pharmacology & therapeutics (ISSN 0163-7258); Volume 62; 1-2; 247-65
    Format: text
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