bluuebunny/crossref_metadata_2025 huggingface dataset:
Scale-space analysis of time series in circulatory research
Authors: Mortensen Kim Erlend , Godtliebsen Fred , Revhaug Arthur
Published: July 2006

Statistical analysis of time series is still inadequate within circulation research. With the advent of increasing computational power and real-time recordings from hemodynamic studies, one is increasingly dealing with vast amounts of data in time series. This paper aims to illustrate how statistical analysis using the significant nonstationarities (SiNoS) method may complement traditional repeated-measures ANOVA and linear mixed models. We applied these methods on a dataset of local hepatic and systemic circulatory changes induced by aortoportal shunting and graded liver resection. We found SiNoS analysis more comprehensive when compared with traditional statistical analysis in the following four ways: 1) the method allows better signal-to-noise detection; 2) including all data points from real time recordings in a statistical analysis permits better detection of significant features in the data; 3) analysis with multiple scales of resolution facilitates a more differentiated observation of the material; and 4) the method affords excellent visual presentation by combining group differences, time trends, and multiscale statistical analysis allowing the observer to quickly view and evaluate the material. It is our opinion that SiNoS analysis of time series is a very powerful statistical tool that may be used to complement conventional statistical methods.
Homocysteine-mediated activation and mitochondrial translocation of calpain regulates MMP-9 in MVEC
Authors: Moshal Karni S. , Singh Mahavir , Sen Utpal , Rosenberger Dorothea Susanne E. , Henderson Brooke , Tyagi Neetu , Zhang Hong , Tyagi Suresh C.
Published: July 2006

Hyperhomocysteinemia (HHcy) is associated with atherosclerosis, stroke, and dementia. Hcy causes extracellular matrix remodeling by the activation of matrix metalloproteinase-9 (MMP-9), in part, by inducing redox signaling and modulating the intracellular calcium dynamics. Calpains are the calcium-dependent cysteine proteases that are implicated in mitochondrial damage via oxidative burst. Mitochondrial abnormalities have been identified in HHcy. The mechanism of Hcy-induced extracellular matrix remodeling by MMP-9 activation via mitochondrial pathway is largely unknown. We report a novel role of calpains in mitochondrial-mediated MMP-9 activation by Hcy in cultured rat heart microvascular endothelial cells. Our observations suggested that calpain regulates Hcy-induced MMP-9 expression and activity. We showed that Hcy activates calpain-1, but not calpain-2, in a calcium-dependent manner. Interestingly, the enhanced calpain activity was not mirrored by the decreased levels of its endogenous inhibitor calpastatin. We presented evidence that Hcy induces the translocation of active calpain from cytosol to mitochondria, leading to MMP-9 activation, in part, by causing intramitochondrial oxidative burst. Furthermore, studies with pharmacological inhibitors of calpain (calpeptin and calpain-1 inhibitor), ERK (PD-98059) and the mitochondrial uncoupler FCCP suggested that calpain and ERK-1/2 are the major events within the Hcy/MMP-9 signal axis and that intramitochondrial oxidative stress regulates MMP-9 via ERK-1/2 signal cascade. Taken together, these findings determine the novel role of mitochondrial translocation of calpain-1 in MMP-9 activation during HHcy, in part, by increasing mitochondrial oxidative tress.
Dexamethasone inhibits the action of TNF on ENaC expression and activity
Authors: Dagenais André , Fréchette Rosalie , Clermont Marie-Eve , Massé Chantal , Privé Anik , Brochiero Emmanuelle , Berthiaume Yves
Published: July 2006

We have reported that TNF, a proinflammatory cytokine present in several lung pathologies, decreases the expression and activity of the epithelial Na+channel (ENaC) by ∼70% in alveolar epithelial cells. Because dexamethasone has been shown to upregulate ENaC mRNA expression and is well known to downregulate proinflammatory genes, we tested if it could alleviate the effect of TNF on ENaC expression and activity. In cotreatment with TNF, we found that dexamethasone reversed the inhibitory effect of TNF and upregulated α, β, and γENaC mRNA expression. When the cells were pretreated for 24 h with TNF before cotreatment, dexamethasone was still able to increase αENaC mRNA expression to 1.8-fold above control values. However, in these conditions, β and γENaC mRNA expression was reduced to 47% and 14%, respectively. The potential role of TNF and dexamethasone on αENaC promoter activity was tested in A549 alveolar epithelial cells. TNF decreased luciferase (Luc) expression by ∼25% in these cells, indicating that the strong diminution of αENaC mRNA must be related to posttranscriptional events. Dexamethasone raised Luc expression by fivefold in the cells and augmented promoter activity by 2.77-fold in cotreatment with TNF. In addition to its effect on αENaC gene expression, dexamethasone was able to maintain amiloride-sensitive current as well as the liquid clearance abilities of TNF-treated cells within the normal range. All these results suggest that dexamethasone alleviates the downregulation of ENaC expression and activity in TNF-treated alveolar epithelial cells.
Development of thermodynamic models for simulating probe dissociation profiles in fluorescence in situ hybridization
Authors: Yılmaz L. Şafak , Noguera Daniel R.
Published: July 2006

Stringency in ribosomal RNA (rRNA)‐targeted fluorescence in situ hybridization (FISH) is typically adjusted with formamide, and the optimum formamide concentration at which the probe can hybridize with the target rRNA, but not with rRNAs with mismatches, is to be found experimentally. This is a difficult task when target or closest non‐target organisms are not available in pure culture, or when there are numerous non‐targets of concern. The objective of this work was to formulate mechanistic models capable of simulating the effect of formamide on probe dissociation. Using a previously described equilibrium model of FISH [Yilmaz and Noguera (2004) Applied and Environmental Microbiology 70(12):7126‐7139] as the basis, the effect of formamide on free energy changes of probe–target duplex formation (ΔG) and folding of target region (ΔG) was simulated to be linear, and models differing in the definitions of the slopes of these relationships (m1 and m3) were calibrated using experimental dissociation profiles for 27 probes targeting the 16S rRNA of Escherichia coli (E. coli). A good level of predictive power was obtained when m1 was linearly related to probe length and when m3 was made proportional to ΔG. The effect of single mismatches on probe dissociation with formamide was also studied, although at a preliminary level. The expected changes in ΔG with the introduction of mismatches were not sufficient to capture the overall trends of mismatched dissociation profiles. In conclusion, this study offers the first theoretical method to calculate dissociation profiles for perfectly matched probes, and suggests a direction to systematically evaluate the effect of formamide on mismatched probes. Biotechnol. Bioeng. 2007;96: 349–363. © 2006 Wiley Periodicals, Inc.
Using an aerosol deposition model to increase hairy root growth in a mist reactor
Authors: Towler Melissa J. , Wyslouzil Barbara E. , Weathers Pamela J.
Published: July 2006

Gas‐phase reactors, including the mist reactor, have distinct advantages over liquid‐phase reactors including the ability to manipulate the gas composition, to allow effective gas exchange in a densely growing biomass, and to affect secondary metabolite production. Mathematical modeling suggested that roots in a mist reactor are often too sparsely packed to capture mist particles efficiently and cannot, therefore, meet the nutrient demands required to maintain high growth rates. Indeed, growth rates of Artemisia annua hairy roots increased significantly when the initial packing density increased or when a higher sucrose concentration was used in the medium. Growth kinetics for 2, 4, and 6 days, however, showed a decrease or stationary growth rate after only 4 days for both 3 and 5% sucrose feeds. Residual medium analyses indicated that carbon was not exhausted, nor were any of the other major nutrients including phosphate. Increasing the mist duty cycle at constant carbon flux through the reactor reduced the growth rates slightly. In general, the aerosol deposition model correctly predicted how to optimize hairy root growth in the mist reactor. Biotechnol. Bioeng. 2007;96:881–891. © 2006 Wiley Periodicals, Inc.
IMPROVEMENTS IN THE STRUCTURAL STATE OF SOILS UNDER LEYS
Authors: LOW A. J.
Published: July 2006

An investigation was made of the time taken by a ley to change the physical state of an old arable soil ro that of an old grassland soil so that, for example, its physical condition on ploughing is the same as that of old grassland on ploughing. The process was found to be slow, taking possibly 50 years or more on some clay soils. On coarse sandy soils the process may be considerably faster, e.g. 5–10 years.
SOILS
Authors: PEREIRA H. C.
Published: July 2006

The ability of the soil surface to accept continuous heavy rainfall is a critical factor in the prevention of accelerated erosion of tropical soils. The qualities required in the soil are complex, and are not easily inferred from simple laboratory measurements. A direct test has therefore been developed for this property. Large soil cores of undisturbed structure are brought to a standard moisture tension, and are subjected to heavy artificial rainfall of controlled drop‐size and intensity. The drainage tension is maintained at a constant value, and the rate of infiltration is measured. The apparatus is described in detail. Examples of results from a tropical rotation experiment are given, in comparison with porespace and percolation measurements.
ESTIMATION OF AVAILABLE NITROGEN FOR ADVISORY PURPOSES IN SOUTHERN RHODESIA
Authors: SAUNDER D. H. , ELLIS B. S. , HALL A.
Published: July 2006

In Southern Rhodesia the nitrogen mineralized on laboratory incubation of soil samples taken towards the end of the dry season appears to provide a good index of the nitrogen likely to be available for crop use under field conditions during the subsequent growing season. Incubation for 2 weeks at 35° C., at moistures near field capacity, has been adopted. The occurrence of some soils showing a time‐lag between the commencement of ammonification and the commencement of nitrification makes it desirable to determine both ammonia‐ and nitrate‐nitrogen. Owing to practical difficulties in obtaining representative samples of both soil and undecomposed organic matter which has been recently ploughed under, and because it has not been found possible to incorporate this organic matter with the soil sample for incubation in such a way as to reproduce, during the incubation period, its overall effect in the field, soil samples for advisory work are at present sieved before incubation and allowances made for the probable effects of such organic matter when interpreting the results obtained.

The nitrogen mineralized during incubation has been shown to be of the same order as that mineralized in miniature lysimeters maintained in the field under bare‐fallow conditions for the duration of the growing season. The mineralized nitrogen obtained after incubation has also been shown to correlate well (r =+.83) with yields, at zero fertilizer‐nitrogen levels, of maize and tobacco obtained in the field during seasons of good rainfall.

Responses to fertilizer nitrogen in Rhodesia have been found to be 1–2 bags of maize or 100‐zoo lb. of tobacco per 10 lb. of nitrogen applied, corresponding to an efficiency of uptake of about 30–60 per cent.
OBSERVATIONS ON THE PEDOLOGY AND FERTILITY OF SOME KRASNOZEMS IN NORTHERN NEW SOUTH WALES
Authors: COLWELL J. D.
Published: July 2006

Eight krasnozem (red‐earth) profiles representing a wide range of environments have been studied. Contrasting features of the soils can be explained by differences in parent material, climate, vegetation, and land use. The main effects corresponding to these variations are seen in the relative contents of total and readily soluble aluminium, organic carbon, nitrogen, organic phosphorus, and of exchangeable metal cations.

Land utilization appears to have led to losses in organic carbon, nitrogen, organic phosphorus, exchangeable cations, and ‘available’ manganese. These losses suggest the possibility of a potassium deficiency and are in agreement with observed nitrogen deficiencies.

The cation‐exchange capacity of the organic matter is much greater than that of the inorganic matter, and in some soils extrapolation suggests that losses of organic matter threaten the capacity of the soils to retain cations.
PROBLEMS OF SOIL HISTORY. PODZOL DEVELOPMENT AT GOODLAND AND TORR TOWNLANDS, CO. ANTRIM, NORTHERN IRELAND
Authors: PROUDFOOT V. B.
Published: July 2006

The formation of podzols with well‐marked iron pans on boulder clay soils overlying chalk is described. A sub‐peat soil at Goodland is to be regarded as a fossil soil with two podzol profiles superimposed. The upper podzol formed in a relatively short time prior to the growth of the overlying blanket bog following tillage which helped to accelerate the rate at which podzolization occurred. A well‐marked iron pan in a podzol at Torr has developed during the past hundred years. The formation of an impermeable humuslayer within the top few inches of such soils leads to waterlogged conditions suitable for the development of blanket bog over them. This humus layer effectively seals the underlying podzol from waterlogged or gleying conditions.

Accepting the hypothesis that the podzol at Goodland is a fossil soil, a chronology for soil development is proposed using archaeological material as dating evidence.
FACTORS AFFECTING THE ABILITY OF PLANTS TO ABSORB PHOSPHATE FROM SOILS
Authors: FOSTER W. N. M. , RUSSELL R. SCOTT
Published: July 2006

In water‐culture experiments of short duration the transfer of phosphate to plant shoots is reduced by ferric iron applied prior to or simultaneously with phosphate. The effect os more marked in barley than in rye. The retention of phosphate in roots is similar whether iron is applied simultaneously with or prior to phosphate. Variation in the concentration of phosphate which is supplied to plants has no corresponding effect on the retention of iron in roots. The evidence presented is compatible with the view that phosphate is restrained in roots by ferric ions which have already combined with immobile organic molecules. The atom ratio of iron to phosphate in the resultant complex appears to be I.

No direct evidence is available to show whether reactions between iron and phosphate within plants contribute significantly to the interaction between the two irons which can occur when plants are grown in soils high in labile iron. This possibility cannot however be discounted.
THE CLASSIFICATION OF GILGAIED SOILS: SOME EVIDENCE FROM NORTHERN IRAQ
Authors: HARRIS S. A.
Published: July 2006

The discrepancies between the classifications of McGarity and Hallsworth et al. are summarized and confirmed with later descriptions by other writers. Further evidence from Northern Iraq shows that gilgai occurs which forms a transition from normal to‘tank’form in several topographic types. A further form of depression gilgai is described completing the four possible combinations of the lattice‐A, wavy, and normal gilgai of Hallsworth et al. Depression forms from the limit of the area in which gilgai occurs are described.

A new classification into gilgai types (based on topography and dominance of shelf and puff) and varieties (based on the nature of the puff and the size of puffs and channels) is suggested.
SOME MEASUREMENTS OF AIR SPACE IN SCOTTISH SOILS
Authors: ROMANS J. C. C.
Published: July 2006

Total air‐space values are related to the hydrologic sequence of soils as described by Glentworth and Dion. The greatest differences within the profile are found in freely drained soils, where from a value of approximately 50 per cent. air space in the B2 horizon there is a drop to 25–35 per cent.(depending on the type of parent material) in the indurated B3 horizon. Imperfectly drained soils have a slightly lower air space in the B2 horizon and values decrease below. Poorly drained soils commonly have values between 35 and 40 per cent. and very poorly drained soils values between 30 and 35 per cent. The tendency for values to decrease in the lower horizons of a gley profile becomes less as the natural drainage conditions deteriorate.
INTERACTION OF IRON WITH RAINFALL LEACHATES*
Authors: SCHNITZER M.
Published: July 2006

Leachates from decomposing leaves of four species of deciduous trees were collected after each rainfall during the months of May to September. Determinations were made of the capacity of these leachates to take up iron from iron‐saturated Dowex‐50 and to withhold this iron from exchange and/or adsorption by exchange resins saturated with H, Al, Ca, and Mn. For both characteristics the leachates ranked maple > poplar > birch > beech. The capacity of ion‐saturated resins to remove iron from iron‐enriched leachates was as follows: H > Al > Ca = Mn. This behaviour may be related to the variable thicknesses of the horizons of eluviation and deposition of iron in various podzolic soils. These horizons are, in general, thinner in the strongly acidic Podzol soils than in Grey‐Brown Podzolic soils more highly saturated with calcium.

Potentiometric titrations of metal‐free and iron‐enriched leachates indicated that titratable acid groups were blocked by the added iron. Apparent pK values of metal‐free leachates ranged from 3·6 to 3·9, those of iron‐enriched leachates, except poplar, from 4·7 to 5·0.
IDENTIFICATION AND SIGNIFICANCE OF BURIED SOILS OF QUATERNARY AGE IN THE SOUTH‐EASTERN PORTION OF THE AUSTRALIAN ARID ZONE
Authors: JESSUP R. W.
Published: July 2006

Two soil layers of Quaternary age are identified. The distribution of the layers, the older of which is buried in some areas and exposed in others, is discussed. The soils in each layer are developed on parent materials of predominantly wind‐transported origin. The juxtaposition, at the surface of the landscape, of soils with contrasting properties, is interpreted in terms of soil layering and history.

Buried soils indicate that periods of soil formation have alternated with periods of erosion‐deposition. The periods of soil formation were associated with relatively humid climates when erosion was at a minimum because the landscape was protected by a well‐developed vegetative cover. Each period of soil formation was followed by a period when the climate became increasingly arid and the vegetative cover was depleted. Desertic conditions led to landscape instability and erosion and deposition by wind.
A TREATMENT OF THE CAPILLARY FRINGE IN THE THEORY OF DRAINAGE
Authors: CHILDS E. C.
Published: July 2006

When a drainage system copes with both artesian and precipitated water the streamline dividing the two flow zones passes through a stagnation point in the medial vertical plane parallel to the drain lines. The approximation is made that the water‐table and capillary fringe boundary may be regarded as those appropriate to precipitated water only, in the presence of an impermeable bed passing through the stagnation point. While the absolute heights may be in error it is shown that the partition of the capillary fringe about the water‐table location in the absence of a fringe is given with only small error. This partition is calculated from hodograph theory with the aid of Edsac 11 for combinations of three values of precipitation rate, seven values of fringe thickness, and nine values of depth of impermeable bed. By interpolation, curves are presented to show the partition for combinations of three selected precipitation rates, five depths of bed, and continuous variation of fringe thickness. It is shown that for high precipitation rates the greatest fringe thicknesses are accommodated almost wholly above that surface which would have been the water table in the absence of a fringe, while for the lowest rates of precipitation and zero bed depth only 30 per cent. of the fringe is so accommodated; the remainder is below.
EFFECT OF DRAINAGE ON CERTAIN PHYSICAL PROPERTIES OF A HEAVY CLAY SOIL
Authors: LEYTON L. , YADAV J. S. P.
Published: July 2006

Comparisons of the physical properties of a drained and undrained heavy clay soil revealed a higher content of water‐stable aggregates, a higher proportion of larger pore spaces and a greater vertical and lateral hydraulic conductivity in the former. The difference generally decreased with depth; at about 15 in there was generally little difference between the two soils. Despite possible initial differences in texture, the difference can be interpreted as being largely due to the effect of drainage on aeration.
CHEMICAL STUDIES OF PODZOLIC ILLUVIAL HORIZONS
Authors: MARTIN A. E.
Published: July 2006

Resin‐treated humus extracts, adjusted to predetermined pH values, were mixed with solutions of FeCl3, FeCl2, or NiCl2, at the same pH. At C/Fe(III) ratios of 3 and 6, maximum precipitation of humus and Fe occurred at pH 2‐3, i.e. the approximate precipitation pH of hydrous ferric oxide. Above pH 3, humus was almost completely dispersed; Fe was partially precipitated at pH 5 without extensive co‐precipitation of humus. At ratios of C to Fe(III) found in the B horizon of a New Zealand podzol (C/Fe(III) = 22), no flocculation of humus occurred at any pH value from 1 to 5. Using FeCl3 and AlCl3 as a mixed flocculant (C/Al =12, C/Fe(III) = 5·8) complete flocculation of humus occurred from pH 1·8 to pH 4. Comparison of the results with data from pure Al and Fe systems suggested that Fe was the active precipitant at pH3 while Al was active from pH 3 to pH 4.

Flocculation of humus by Fe(II) was complete at pH 6‐7, but only at C/Fe(II) = I. At C/Fe(II) = 2 flocculation was partial, the maximum occurring at pH 5. As with the ferric systems, maximal flocculation appears to occur at about the precipitation pH of the metal ‘hydroxide’. Nickel (C/Ni = 3) did not flocculate humus at any pH from 1 to 8. Thus greater amounts of divalent ions are needed to flocculate humus, in agreement with the Hardy‐Schulze effect.

Experiments testing the effect of atmospheric oxidation of ferrous‐humus systems on flocculation were, in general, inconclusive, although slight precipitation of humus was observed following aeration of a ferrous‐humus system at pH3.

Changes in pH occurred on mixing humus with all metal solutions studied, whether flocculation occurred or not. These changes were negative below a critical mixing pH which depended on the metal species used, and positive above this value. The critical pH values for Fe(III), Fe(II), and Ni were 2·8,6·8‐7·8 (depending on reaction time), and 8·0 respectively; for a mixed Fe(III)‐Al system the critical pH was 4·2. An interpretation of these changes is suggested in the case of ferric iron, that is based on that previously postulated for Al.

Semi‐quantitative experiments showed that Ni, Fe(II), and Al ions possess additive properties in flocculation of podzol humus at pH 2·96. Organic matter which contained slightly less than the critical amount of Al necessary for flocculation was still dispersed but highly sensitive towards the addition of small amounts of Fe(II) or Ni which by themselves were without effect. Freshly precipitated hydrous ferric oxide did not sensitize humus towards flocculation by Al at pH 3·2, although considerable amounts of Fe(III) could be co‐precipitated by adding Al in excess of the critical concentration.
THE MECHANISM OF SURFACE NITRATE ACCUMULATION ON A BARE FALLOW SOIL IN UGANDA
Authors: SIMPSON J. R.
Published: July 2006

In a red latosol loam under bare fallow at Kawanda, Uganda, nitrate accumulates to as much as 70 p.p.m, nitrate nitrogen during short periods of dry weather. Nitrate accumulation appears to be a microbiological process involving nitrifying bacteria similar to Nitrosomonas and Nitrobacter. Nitrate accumulation in an isolated topsoil, 3 in. deep, ceased when the moisture content fell below 10 per cent. Accumulation continued on plots which were in contact with the subsoil and which remained at 10 per cent. moisture.

It was concluded that under the conditions of these experiments, transport of ions to the surface by capillary transport or diffusion does occur, but is not responsible for the major nitrate accumulation, which seems to depend on progressive drying of the topsoil during which nitrate, as formed, becomes protected by the dry conditions from microbial reduction, assimilation, and leaching. Any process which prevents the progressive drying, e.g. shading, mulching, and watering, can be expected to favour nitrate removal and so to prevent nitrate accumulation.
POST‐GLACIAL SEDIMENTS AS A RECORD OF REGIONAL SOIL DRIFTS
Authors: PEARSALL W. H. , GAY JOYCE , NEWBOULD JOSEPHINE
Published: July 2006

Analytical data are given for deep‐water sediments from Esthwaite Water in the English Lake District representing different depths below the mud surface and sediments of ages back to and including the late‐glacial, of which the pollen status is known. Nitrogen content and loss on ignition increase steadily in muds laid down during the time of post‐glacial forest development, showing also a small previous rise which represents the temporary late‐glacial climatic amelioration (Allerad). Nitrogen remains approximately constant in muds representing the stage of post‐glacial alder‐oak‐birch forest. Deforestation, as shown by increases in grass pollen in the muds, is associated with falls in the values for nitrogen and loss‐on‐ignition. These decreases occur in two stages, believed to represent two stages of human settlement and land use.

Analyses for elements such as sodium, potassium, magnesium, calcium, and iron, show signs of increasing solubility in the muds representing the time of forest development. Thereafter the amount of calcium diminishes progressively in later muds, while the Ca/Fe ratio falls, changes which could be correlated with the leaching effects of a rainfall of 170‐zoo cm. per annum on the soils in the lake basin. Similar data are recorded for a core from Rydal Water.

The results are interpreted as records of the regional changes in soils from the lake drainage systems during the post‐glacial period.
AN INTRODUCTION T O THE SOILS OF THE SOUTH‐EASTERN PORTION OF THE AUSTRALIAN ARID ZONE
Authors: JESSUP R. W.
Published: July 2006

Seven soil regions, each of which is dominated by soils belonging to one or two great soil groups, are defined and mapped. The outstanding feature is the presence of a variety of soils with widely differing characteristics. The soils are deeper, have more profile differentiation and are finer‐extured than those in most‐arid regions and are frequently overlain by currently‐forming deposits of wind‐transported materials. Because the vegetative cover is better developed and there are only small areas of rocky hills and bare rock pediments, water erosion and deposition are not as prominent as in other arid areas.
EVOLUTION OF THE TWO YOUNGEST (QUATERNARY) SOIL LAYERS IN THE SOUTH‐EASTERN PORTION OF THE AUSTRALIAN ARID ZONE
Authors: JESSUP R. W.
Published: July 2006

The calcareous materials in the deposits, on which the Bookaloo soils developed, were transported by wind. They were derived through deflation of older soils that occurred both within the region and in an area lying to the west. Wind erosion in the region was confined to a zone in which the climate became arid. Beyond the arid zone there was a sufficient cover of vegetation for landscape stability. In some localities deposits of wind‐blown materials accumulated in the beds of relic streams. The present drainage lines are incised in these deposits.

The soils, whose profiles are characterized by only weak horizon differentiation, developed following the onset of wetter climatic conditions.
INFLUENCE OF SOIL‐WATER SUCTION ON SOME MECHANICAL PROPERTIES OF SOILS
Authors: TOWNER G. D.
Published: July 2006

The experiments described, using kaolinite, were designed to prove the theory that for a saturated soil internal soil‐water suction is quantitatively equivalent to an externally applied all‐round mechanical pressure.
MISCIBLE DISPLACEMENT IN POROUS MATERIALS
Authors: BIGGAR J. W. , NIELSEN D. R.
Published: July 2006

Miscible displacement has been studied in several porous materials under saturated and unsaturated conditions at different average flow velocities. The tracer appeared at the end of the soil column sooner than would be expected, had no mixing occurred at the boundary of the tracer and tracer‐free water. Physical differences between porous materials were manifested by changes in shape and position of break‐through curves owing to ionic diffusion. One of the more important physical features was the magnitude of the volume of water not readily displaced at saturation and its increase when the soil was desaturated. Because the total flux of water moving through field soils is generally small, the role played by hydrodynamic dispersion and diffusion in transporting dissolved solutes must be included in the theory of most soil‐water processes.
EXCHANGEABLE BASES OF MATURE, WELL‐DRAINED SOILS IN RELATION TO RAINFALL IN EAST AFRICA
Authors: SCOTT R. M.
Published: July 2006

At low levels of annual rainfall, leaching of bases with falling percentage saturation follows a simple physical pattern, but as rainfall rises above a level sufficient for reasonable plant growth, intrusion of the biological factor leads to a recirculation of bases and even to an accumulation in the solum with the result that percentage saturation rises once more to an optimum at about 46 in. rainfall and falls away with further increase in rainfall.

These changes in percentage saturation are independent of the base‐exchange capacity of the parent material, and the total exchangeable bases in a soil are determined by the base‐exchange capacity of the parent material and the rainfall régime to which it has been subjected.
THE SWELLING OF CA‐MONTMORILLONITE DUE TO WATER ABSORPTION
Authors: EMERSON W. W.
Published: July 2006

The increase in thickness of dry orientated flakes of Ca‐montmorillonite about 0·2 mm. thick, prepared from Wyoming bentonite, when brought into vapour equilibrium with solutions of increasing relative vapour pressure has been measured with a travelling microscope. The three solutions used were sat. NH4H2PO4 (P/P0= 0·92), sat. Ba(NO3)2 (p/p0= 0·985), and water (p/p0= 1·0). X‐ray and water‐absorption measurements were also made on separate portions of the flakes at these values of p/p0. The density of the dry clay and the apparent density of the dry flake were determined. As the lateral swelling of the flakes was found to be very small compared with the swelling perpendicular to the general plane of orientation of the crystals, the distribution of air and water in the flakes could then be calculated at each value of p/p0.

Up to p/p0= 0·985, 80 per cent. of the water absorbed by the flake was accounted for by the increase in the thickness of the water films on the clay crystals, the remaining water filling about half the pore space. On the basis of the total volume of the flakes, the total pore space was reduced by 12 per cent. at p/p0= 0·92 compared with the dry flake, due to expansion of the crystals, but then remained the same up to p/p0= 0·985. Between p/p0= 0·985 and 1·0, the pore space in the flake was filled and a further small expansion of the flake occurred, but the (001) spacing did not increase beyond 18·9 Å. Swelling in the vapour phase was unaffected by addition of I per cent. CTAB to the clay. The relation between macroscopic swelling and increase in water‐film thickness is consistent with the crystals being in the form of a tactoid.

The swelling as p/p0→ 1·0 was much lower than that of a flake immersed in liquid water (see Part 2). It is suggested that this arises from the formation of polymolecular layers of water on the surfaces of the clay crystals, due to the influence of the exchangeable‐Ca ions which differ in structure from that of bulk water.
UPWARD MOVEMENT OF NITRATE IN A BARE SOIL IN UGANDA
Authors: STEPHENS D.
Published: July 2006

The levels of added chloride and nitrate in the topsoil of a well‐drained red clay loam have been measured throughout two dry seasons and evidence obtained that a small upward movement of dissolved salt can occur. The extent of this movement was not, however, sufficient to account for the observed accumulation of nitrate in the surface soil and it is concluded that the greater part of this nitrate was produced by some other process, such as microbial activity.
A STUDY OF ORGANIC SOIL HORIZONS USING ELECTROPHORETIC TECHNIQUES
Authors: MACKENZIE A. F. , DAWSON J. E.
Published: July 2006

Saturated sodium‐pyrophosphate extracts were obtained from samples of Sphagnum‐moss peat, sedimentary peat, fibrous peat, disintegrated peat, and muck and were subjected to electrophoretic separation and analysed for organic matter, polysaccharides, and coloured material. The resulting patterns indicated a marked difference between the muck samples and the peat samples. The high exchange‐capacity values obtained for muck samples were associated with the amount of highly charged material rather than with an increase in the charge density of this material. The muck and the fibrous‐peat samples appeared to be end members in a disintegration and oxidation sequence involving many intermediate stages.
AN EXAMINATION OF CATION BALANCE AND MOISTURE CHARACTERISTIC METHODS OF DETERMINING THE STABILITY OF SOIL AGGREGATES
Authors: COLLIS‐GEORGE N. , SMILES D. E.
Published: July 2006

For artificially reconstituted aggregates of soils low in organic matter the definitions of the stability of structure in terms either of cation balance and cation concentration of the ambient solution or of the drainage moisture contentsuction relationship characteristic after slow wetting are consistent.

Identified factors of organic matter and of heating and drying (or drying alone) confer a structural stability on aggregates which can be detected by the moisture characteristic method. There is circumstantial evidence to suggest that the organic matter must be in equilibrium with vegetation.

Since more than one factor affect structural stability, and since any particular method of distinguishing between different degrees of this stability may not necessarily suit the range of stabilities presented, the independent identification of soils, known to behave with differing aggregate structural stability in the field, is not necessarily possible with any laboratory method which describes changes in structural stability.
THE INFLUENCE OF IRON ON THE STABILITY OF SOIL ORGANIC MATTER DURING PEROXIDATION
Authors: OADES J. M. , TOWNSEND W. N.
Published: July 2006

The oxidation of soil organic matter by hydrogen peroxide is shown to be incomplete, the resistant organic materials causing sharp exothermic reactions at 300–340°C. during differential thermal analysis in an atmosphere of oxygen. Removal of the materials responsible for these exothermic reactions by treatments with sodium dithionite, sodium pyrophosphate, and acetylacetone followed by determination of iron in the acetylacetone extracts shows that iron is responsible for the stability of the organic materials, which are probably artefacts produced during the oxidative degradation of the soil organic matter.
THE DETECTION OF FERROMAGNETIC MINERALS IN SOILS AND CLAYS
Authors: OADES J. M. , TOWNSEND W. N.
Published: July 2006

A method is described to measure the magnetic susceptibility of soils and clays using an analytical balance and a small magnet. Small amounts of ferromagnetic iron oxide occur in most soils and are concentrated in the clay fractions of surface horizons. Ignition of soil samples is shown to cause large increases in the magnetic susceptibility.
SELF‐DIFFUSION OF IONS IN SOIL
Authors: GRAHAM‐BRYCE I. J.
Published: July 2006

Self‐diffusion coefficients for I‐ and H2PO‐4 in soils have been measured by determining the movement of radioactive tracers of these ions from a cylindrical section of labelled soil to a similar section initially without tracer. DI varied with the composition of the equilibrium soil solution used, both concentration and nature of cation affecting the value. These results may be explained by variations in the extent of negative adsorption of diffusing anions in the presence of negatively charged soil particles, and the consequent variation in the size of pore from which the anions are excluded.

Phosphate diffusion was measured in the natural soil. The low values of DH2PO4 are attributed to adsorption and fixation of phosphate ions. Results obtained using different methods of phosphorus extraction and treatments designed to investigate effects of microbial activity are discussed.
SOLUBILITY STUDIES OF PHOSPHORUS IN SOME CALCAREOUS MANITOBA SOILS
Authors: WEIR C. C. , SOPER R. J.
Published: July 2006

The concept of chemical potential was applied in studying the form of soil phosphate present in some Manitoba soils. Generally for all the soils studied, the soil phosphates were more soluble than hydroxyapatite but less soluble than dicalcium phosphate dihydrate. Evidence was obtained for the existence of octocalcium phosphate in most of these soils. The effect of phosphate fertilization and per cent calcium carbonate on the form of native soil phosphate was also evaluated.
AN EXAMINATION OF SOME FACTORS AFFECTING THE MOVEMENT OF CLAY IN AN ARTIFICIAL SOIL
Authors: HALLSWORTH E. G.
Published: July 2006

A preliminary study has been made of the extent to which clay can be moved by percolating solutions through various mixtures of sand and clay. The variations studied have been quantity of clay present, type of clay mineral, size distribution of the mineral skeleton, pH of the leaching solution and the nature of the cations present. The movement of the clay was restricted as the proportion present increased, and appeared to cease when the quantity exceeded 40 per cent for kaolinite clay or 20 per cent for montmorillonite clay. At these levels, however, a significant migration was found to occur down the cracks which develop when the soil is dried out. The movement of kaolinite increased continuously with increase in pH. The movement of montmorillonite increased to pH 10 or pH 11, and then rapidly diminished. The effects of the cations showed an interaction with the pH of the leaching solution.
STUDIES ON SOIL POTASSIUM
Authors: TINKER P. B.
Published: July 2006

The method of determining the activity ratio
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(AR) described by Beckett in Part II of this series was applied to a range of moderately to intensely acid Nigerian soils. With the highly acid soils it was necessary to add aluminium ions to the solution to obtain equilibrium. A method for obtaining the true equilibrium solution composition for K, (Ca±Mg), and A1 is described, and a series of typical results given. It was necessary to add benzene to prevent biological activity during sedimentation at 33° C. Altering the total concentration of the solution did not affect the activity ratio. A minority of soils showed evidence of transfer of potassium to non‐exchangeable forms during equilibrium. The slopes of the (exchangeable K)‐AR curves in a single soil were dependent on the amounts of soil Ca±Mg present. In comparisons between several soils, exchange capacity also had an effect. The Gapon equation was approximately correct for these soils over limited ranges.
INFLUENCE OF ORGANIC MATERIALS ON THE DETERMINATION OF THE SPECTFIC SURFACE AREAS OF SOILS
Authors: BURFORD J. R. , DESHPANDE T. L. , GREENLAND D. J. , QUIRK J. P.
Published: July 2006

The surface areas of a number of soils have been determined before and after removal of organic matter by treatment with hydrogen peroxide. The external area as determined by low‐temperature nitrogen adsorption increased after peroxidation. The total area derived from the nitrogen area and cetyl pyridinium bromide (CPB) adsorption generally decreased. Part of the clay‐organic complex was separated from some soils, and the external and total surface areas of this material before and after peroxidation determined similarly. Both the external and total areas increased after peroxidation. These results indicate that soils contain organic materials which are not part of the clay‐organic complex and which adsorb large amounts of CPB on surfaces not accessible to nitrogen molecules. A sample of peat showed a correspondingly high CPB adsorption and low nitrogen area. The large differences that occur in the nitrogen and CPB areas after peroxidation show the importance of removal of organic matter prior to the determination of the surface areas of soil clays. The surface areas were only slightly greater when carbon was completely removed by 30 per cent peroxide than when it was partly removed by 6 per cent peroxide. Organic compounds associated with the clay in the clay‐organic complex are apparently able to prevent access of nitrogen molecules to many of the clay surfaces, and also probably exclude CPB from some of these surfaces.
POLYPHENOLS IN PLANT, HUMUS, AND SOIL
Authors: DAVIES R. I. , COULSON C. B. , LEWIS D. A.
Published: July 2006

The leuco‐anthocyanin and tannin contents of green leaves of several species collected at mull sites have been compared with those collected at mor sites. Species growing under mor conditions usually contain greater amounts of both than the same species under mull. By growing a number of plants in sand it has been shown that this high content of polyphenolic substances can be associated with lack of nitrogen or of phosphorus.
THE DESCRIPTION OF RELIEF IN FIELD STUDIES OF SOILS
Authors: CURTIS L. F. , DOORNKAMP J. C. , GREGORY K. J.
Published: July 2006

Landscape information relevant to site description is discussed. It includes surface form (in plan and profile), micro‐relief, aspect, height above sea level, and relative relief of the site in the local setting. Techniques for description of surface form are described which require the recognition and mapping of breaks and changes of slope bounding morphological units of the landscape. These units consist of ‘flats’ and ‘slopes’ that make up the facets of the landscape and may possess characteristic angles. The regional setting of the site is described by morphological map, values for drainage density and stream frequency, location with respect to drainage lines of a particular order, and the directional pattern of facets. Methods for the record of surface profiles by observation and measurement of small‐scale morphological units are described. A slope classification appropriate to British conditions is put forward.
THE MICROFLORA OF PEAT‐PODZOL TRANSITIONS
Authors: HOLDING A. J. , FRANKLIN D. A. , WATLING R.
Published: July 2006

Bacteria made up an average of 90 per cent of the microbial populations of twenty‐four soil samples, mainly of the A0H horizon, from four peat‐podzol transitions. Bacillus spp., which averaged 67 per cent of these bacteria, were usually the predominant group. Gram‐negative non‐spore‐forming organisms (15 per cent), Streptomyces (8 per cent), and Gram‐positive cocci (5 per cent) occurred irregularly and Arthrobacter and Nocardia strains rarely. A large proportion of the strains utilized glucose and malate, and a smaller proportion starch, citrate, and protein. A few strains liquefied pectin but none decomposed cellulose or xylan. In eight populations examined, 80 per cent of the bacteria required yeast extract for growth. Fungi usually formed only a small proportion of the populations. All the species, except Penicillium nigricans and Trichoderma viride, were isolated from only one transition. Yeasts occurred irregularly, usually in small numbers. Whilst no microbial group responded to the addition of glucose, nitrate, and phosphate to two soil samples, bacterial numbers increased after the addition of peptone and yeast extract.
EFFECTS OF AIR‐DRY, REFRIGERATED AND FROZEN STORAGE ON ACTIVITIES OF ENZYMES HYDROLYSING SUCROSE AND STARCH IN SOILS
Authors: ROSS D. J.
Published: July 2006

Activities of enzymes hydrolysing sucrose and starch were lowered significantly in all air‐dried soils, except some naturally arid soils, stored at room temperature by more than 20 per cent and 50 per cent respectively, compared with values for fresh soils. These reductions in activities resulted mainly from the initial drying which also appreciably reduced the numbers of viable bacteria. Activities of enzymes hydrolysing sucrose generally decreased on storage at −20° C but changes were slight over long periods. Inactivation of enzymes hydrolysing starch was greater and tended to increase with length of storage. Inactivation was due partly to the effects of freezing and thawing and was greater in dry than in moist samples of soils. Activities were changed least by storage at 4° C and a significant decrease from fresh values was found occasionally in only two of the thirteen soils. Starch‐hydrolysing activity was significantly increased in two very moist soils stored for 41 weeks, probably due to germination of a few seeds. Although different soils can differ in their storage behaviour, storage in a refrigerator is most suitable and air‐drying least suitable for subsequent assays of these enzymes.
SOLUBLE AND EXCHANGEABLE CATION RATIOS IN SOME SOILS OF ISRAEL1
Authors: LEVY RACHEL , (MURAVSKY) E. MOR
Published: July 2006

Sodium‐absorption ratio–exchangeable sodium ratio relationship was tested on some Israeli profiles. Two approaches were used: firstly, a survey on existing relationship in about 250 soil samples representing twenty soil types, and secondly, a comparison of the exchange isotherms of five soil types obtained by a batch equilibrium procedure. The results of the survey extended over a small range of S.A.R., a fact which was an obstacle for making any conclusions. By the second approach it was found that the examined soil types showed a difference in their exchange properties. Determination of the exchange isotherms and calculation of the parameters for each soil separately gave a better insight into their exchange behaviour.
THE INFLUENCE OF TEXTURE ON THE MOISTURE CHARACTERISTICS OF SOILS
Authors: SALTER P. J. , WILLIAMS J. B.
Published: July 2006

The available‐water capacity of the top 2 ft of twenty‐seven soils of different texture has been determined, together with the moisture release characteristics of twenty of the soils. The moisture contents at field capacity and at the permanent wilting point increased as the soils became finer in texture but the medium‐textured soils held the greatest volume of available‐water. The available‐water capacities of the soils ranged from 0.77 in./ft depth in a sand to 3.12 in./ft in a silt loam and 3.13 in./ft in a peat. Clay soils held approximately 1.95 in./ft. The effects of soil texture and other factors affecting the available‐water capacities and moisture release characteristics of soils are discussed.
CLASSIFICATION OF SOILS BY NUMERICAL METHODS
Authors: RAYNER J. H.
Published: July 2006

Twenty‐three profile descriptions of soils in Glamorganshire and the laboratory measurements on soil samples of the ninety‐one horizons into which they were divided by the surveyor were examined by the methods of numerical taxonomy. The similarities between the horizons calculated by these methods were reduced to a table of similarities between profiles by averaging the similarities of those horizons that matched best, judged by their similarity and order in the profile. The soil‐similarity matrix was sorted to give a dendrogramme. Calculation of the latent roots and vectors of the matrix gave a two dimensional representation of the relationships between the soils. The Great Soil Groups to which the surveyor assigned his profiles can be picked out in this diagram.