bluuebunny/crossref_metadata_2025_split huggingface dataset:
Critical state soil mechanics analysis of the constant cell volume triaxial test
Authors: KIRBY J.M. , O'SULLIVAN M.F. 
Published: August 2005

SummaryWe have developed a critical state, stress‐strain analysis that predicts the entire sequence of states from start to the end of a constant cell volume triaxial test in p‐q‐v‐ɛz, space, where p is the spherical stress, q is the deviator stress, v is the specific volume and ɛz is the axial strain. The analysis requires five soil properties to be specified, these being the critical state properties (M, λ and κ) and two elastic properties (any two of E, η, G and K—all four can be found from any two).In order to test the analysis, properties taken mostly from one series of constant cell volume triaxial tests are used to simulate the behaviour in a second test series. In both series the two soils (a sand loam and a clay loam) were tested at several different water contents. The first (property estimation) series of tests was performed using large samples, whereas the second (verification) series involved small samples. The behaviour is quite different in the two series. The elastic property E was not determined in the first series of tests but was estimated from the second series. Furthermore, for three very wet samples, λ had to be estimated by fitting the analysis to the data. The verification was not therefore fully independent of the input test data, particularly for the three wet samples. The stress strain analysis simulated the behaviour of both series of tests in all four dimensions of the p‐q‐v‐ɛz space. The match in p‐q‐v space was good for all samples. On a q‐ɛz plane, the value of q was under‐estimated for several samples, but for most of the samples the match was good on this plane. The analysis was generally as good as, and sometimes better than, a previous analysis that deals only with the end point of the test in p‐q‐v space. The previous analysis did not take account of the elastic properties. The stress‐strain analysis therefore seems to offer a useful framework for parameter estimation from constant cell volume triaxial tests. This extends the usefulness of the test itself, as the elastic properties may now be accounted for. The success of the analysis also strengthens the record of success of the critical state concept for unsaturated soils.
Effects of crystallinity of goethite: II. Rates of sorption and desorption of phosphate
Authors: STRAUSS R. , BRÜMMER G.W. , BARROW N.J. 
Published: August 2005

SummaryEight samples of goethite ranging in surface area from 18 to 132 m2 g‐1 were mixed with phosphate at a range of pH values for periods which ranged from 0·5 h to 6 weeks. The sample with a surface area of 18 m2 g‐1 had been hydrothermally treated to improve its crystallinity. Its rate of reaction with phosphate depended on pH but was complete within a day. Its maximum observed reaction was close to the theoretical maximum for surface adsorption of 2·5 μmol m−2. For the other samples, phosphate continued to react for up to 3 weeks and exceeded the value of 2·5 μmole m−2. The duration and extent of the reaction depended on the crystallinity of the goethite. The results were closely described by a model in which the phosphate ions were initially adsorbed on to charged external surfaces. The phosphate ions then diffused into the particles. This was closely described using equations for diffusion into a cylinder.Samples of goethite which had been loaded with phosphate dissolved more slowly in HCl, and had a longer lag phase, than phosphate‐free goethite. For the hydrothermally treated goethite, HCl removed much of the phosphate when only a small proportion of the iron had been dissolved. For a poorly crystallized goethite, it was necessary to dissolve much more of the iron to obtain a similar removal of phosphate. Brief treatment with NaOH removed most of the phosphate from the hydrothermally treated goethite but only half the phosphate from a poorly crystallized goethite. These results are consistent with the idea that phosphate ions were not only bound on external surface sites but had also penetrated into meso‐ and micro‐pores between the domains of the goethite crystals and were then adsorbed on internal surface sites. This penetration tied the domains together more firmly thus increasing the lag phase for dissolution. Differences between sites for phosphate adsorption are therefore caused mainly by their location on either external or internal sites. Models that ignore this are incomplete.
Computer modelling of partial specific volumes of humic substances
Authors: BIRKETT J.W. , JONES M.N. , BRYAN N.D. , LIVENS F.R. 
Published: August 2005

SummaryThe determination of the structure of humic substances from peat soils and natural waters is a major problem in soil science. Humic substances are chemically heterogeneous and consist of molecules covering a wide distribution of molecular size. A quantity related to both molecular size and structure in the hydrated state is the volume of the humic molecules per unit mass or partial specific volume (ν2). The partial specific volumes of humic substances have been estimated from atom and chemical group volume contributions for 17 proposed structures of fulvic and humic acids taken from the literature. The results show that the partial specific volume reflects the composition of humic substances, decreasing with increase in the carbon: hydrogen (C:H) molar ratio. The more oxidized the humic material the smaller is its partial specific volume. These trends agree with our experimental measurements of partial specific volumes for a range of humic materials (aquatic fulvics, aquatic and peat humics). The predicted values of partial specific volumes for the proposed structures, however, are overestimated by approximately 15% compared to the experimental values. There is little difference between values of ν2 calculated from the detailed humic structures and those calculated from their empirical formulae; calculations of partial specific volumes using a random modelling approach leads to overestimation by approximately 37%. It seems that the estimates based on additivity of atom and chemical group volumes do not take into account an overall contraction of the structures because of hydrophobic interactions. In general terms the values of the partial specific volumes of humic substances suggest they are more compact molecules than globular proteins, and intrinsic viscometry studies suggest that aqueous salt solutions approach θ‐solvent conditions for humic substances.
Some microscopic mineral particles of biological origin in soil solutions
Authors: KELLER C. 
Published: August 2005

SummarySoil solutions leaching from lysimeters and soil suspensions were observed under Transmission Electron Microscopy to reveal small particles (400 nm to few micrometers) of apparently biological origin. Some of the particles are displayed: most of them are scales of protists such as Paraphysomonas(algae), Gyromitus, Acanthocystis and Thaumatomastix (flagellates) which have not been observed previously in soil or soil solutions.
Carbonate redistribution and hydrogeochemical processes in two calcareous soils with groundwater in a Mediterranean environment
Authors: BOUZIGUES R. , RIBOLZI O. , FAVROT J.C. , VALLES V. 
Published: August 2005

SummaryThe morphology of the soil is closely associated with water regime and redistribution of solutes. We studied in detail two calcareous soils with groundwater representative of the two main hydro‐geological regimes, one on the plateau and the other in the central depression, of an experimental catchment near Roujan in the South of France. We recorded macro‐and micromorphological features, and measured the level of the water table and the saturating solution. The morphological features were primarily those associated with carbonate redistribution. The forms associated with iron and manganese added information. The two groundwater systems behaved differently over 3 years. The temporary perched groundwater of the plateau was characterized by a small partial pressure of CO2 (pCO2) and a large pO2, with rapid lowering of the water table (4–6 cm d−1). The permanent groundwater of the depression, in contrast, had a larger pCO2 and a small pO2. The water table fell more slowly (1–2 cm d−1). Higher up, rapid drying of the profile and release of CO2 leads to over‐saturation of the soil solution with respect to calcite, favouring the formation of poorly crystallized micrites, which are characteristic of the plateau system. In the lower part of the catchment, persistent waterlogging leads to more marked anaerobiosis (large estimated pCO2) favouring the development of large stable rhombohedral crystals characteristic of more stable hydrodynamic conditions. In both situations, iron and more particularly manganese redistribution agrees with the waterlogged state of these soils.
Release and fixation of potassium by a loamy soil as affected by initial water content and potassium status of soil samples
Authors: SCHNEIDER A. 
Published: August 2005

SummaryTo understand the contribution of non exchangeable potassium to plant nutrition the release and fixation of K was studied on a range of soil samples of varying K status, obtained from a long‐term fertilizer trial. The soil samples were either air‐dried or not prior to use so as to determine the influence of pretreatment on release and fixation of K. Sorption and desorption of K were measured by following the changes in solution K and exchangeable K, and calculating the relative contributions of exchangeable and non exchangeable K to K dynamics in the soil‐solution systems. The change in the amount of non exchangeable K is proportional to the difference between the initially imposed concentration and the concentration for which neither sorption nor desorption occurred. Whether release or fixation occurs depends on the sign of this difference. Soils containing much K release more K than those containing little K at the same initial or final concentration in solution. The threshold exchangeable potassium and the threshold K concentration for which release becomes large increase when K content increases in the soil. For air‐dried soils K‐enriched soils fixed less K than those containing little K. But when kept moist the soils fixed no K. The threshold exchangeable potassium of release and the minimal exchangeable potassium, i.e. that part of exchangeable potassium extracted by ammonium acetate but which is not in exchange equilibrium with Ca, are useful criteria to assess the meaning of the exchangeable potassium when used as a fertility indicator.
The response of soil organic matter to manure amendments in a long‐term experiment at Ultuna, Sweden
Authors: GERZABEK M.H. , PICHLMAYER F. , KIRCHMANN H. , HABERHAUER G. 
Published: August 2005

SummaryIn a long‐term field experiment started in 1956 on a clay loam soil at Uppsala, Sweden, changes of organic carbon in the topsoils receiving various organic amendments at the rate of 200 kg C ha'1 year'1 were studied to determine soil organic matter characteristics, variations of δ13C in the soil and to estimate a carbon balance. Fallow and mineral fertilizer without N led to a significant decrease of soil organic matter (SOM) in the soil, green manure maintained the SOM content, and animal manure and peat increased the SOM content significantly. The stable portion of the added organic materials after 37 years of continuous input was 12·8, 27·3, and 56·7%, for green manure, animal manure and peat, respectively. This was reflected by half‐lives of organic carbon originating from the amendments between 3·0 (green manure) and 14·6 years (peat). The isotopic composition of SOM changed both due to mineralization (continuous fallow) and the addition of amendments is topically different from soil humus (green manure, animal manure). The isotopic effect was used to calculate the percentage of carbon derived from animal manure present for the year 1993. This value (55·4%) was larger than that derived from the carbon balance, which indicated a priming effect of the animal manure on the initial soil humus. Mineralization of microbially available organic substances led to an increase in the degree of humification on plots not receiving organic amendments. Adding peat and animal manure resulted in a decrease of the humification index due to the continuous input of poorly humified material. The extinction ratio (E4/E6) and ratio of fulvic acid to humic acid changed considerably in the peat treated plots. Fourier transform infrared (FTIR)‐measurements of the extracts showed that peat characteristics can be detected in peat treated soils. The other amendments did not alter the characteristics of the extractable humic substances.
Testosterone Regulates Androgen Receptor Immunoreactivity in the Copulatory, but not Courtship, Neuromuscular System in Adult Male Green Anoles
Authors: Holmes M. M. , Wade J. 
Published: August 2005

AbstractAndrogens regulate the expression of male reproductive behaviour in diverse vertebrate species, often acting on androgen receptors (AR) to induce structural or functional changes in the nervous system and periphery. Male green anoles possess two sexually dimorphic neuromuscular systems, one controlling throat fan (dewlap) extension, which occurs during courtship, and the other mediating copulatory organ function. Although androgens are required for behavioural activation in both systems, testosterone has differential effects on the neuromuscular morphology. It increases the size of copulatory muscle fibres during the breeding season, but significant effects on dewlap muscle fibre size and motoneurone soma size in either system have not been detected. Corresponding to the lack of testosterone‐induced morphological effects in the courtship system, relatively low levels of AR are expressed in the associated motoneurones. The present experiment had two goals, aiming to determine whether: (i) the other courtship and copulatory neuromuscular tissues express AR and (ii) testosterone and/or seasonal environmental changes regulate AR expression. The percentage of AR+ nuclei was evaluated in both the breeding and nonbreeding seasons in gonadally intact adult males (Experiment 1) and in castrated males treated with either testosterone or vehicle (Experiment 2). AR was extensively expressed in the dewlap and copulatory muscles, and in a high percentage of the copulatory motoneurones, but immunoreactivity did not vary across season. Testosterone increased the percentage of AR+ nuclei in the copulatory muscles of both breeding and nonbreeding males but not in the dewlap muscle or copulatory motoneurones. Finally, the target structures for both systems (cartilages and hemipenes) expressed AR in all animals. Therefore, the effects of testosterone on AR immunoreactivity suggest that up‐regulation of the receptors may be important for morphological change. However, because all structures investigated in the present experiment expressed AR, the data also indicate that the receptors are involved with other functions.
Ghrelin‐Induced Stimulation of Colonic Propulsion is Dependent on Hypothalamic Neuropeptide Y1‐ and Corticotrophin‐Releasing Factor 1 Receptor Activation
Authors: Tebbe J. J. , Mronga S. , Tebbe C. G. , Ortmann E. , Arnold R. , Schäfer M. K.‐H. 
Published: August 2005

AbstractPeptides participating in the hypothalamic control of feeding behaviour are also involved in the central autonomic control of gastrointestinal functions, such as secretion and motility. An anatomical interaction and functional relationship in the central nervous system between the feeding‐related peptides neuropeptide Y and ghrelin is well documented. Furthermore, it has been shown that feeding‐related peptides can influence digestive function via central corticotrophin‐releasing factor (CRF) pathways. In the present study, we investigated the role of ghrelin in the central autonomic control of colonic motility. Furthermore, we addressed the hypothesis that ghrelin is involved in the hypothalamic control of colonic motor function, utilizing central neuropeptide Y receptors and hypothalamic CRF pathways. Ghrelin (0.03, 0.06 and 0.12 nmol) bilaterally microinjected into the paraventricular nucleus (PVN) induced a significant stimulation of colonic propulsion. In particular, the colonic transit time decreased from 312 ± 7 min to 198 ± 12 min. Microinjection of the neuropeptide Y1 receptor antagonist, BIBP‐3226 (200 pmol), or the nonselective CRF receptor antagonist, astressin (30 pmol), into the PVN abolished the stimulatory effect of ghrelin injected into the PVN on colonic transit time, whereas pretreatment with the selective CRF2 receptor, antisauvagine‐30 (28 pmol), failed to affect the effect of PVN‐ghrelin injection on colonic propulsion. These results suggest that ghrelin can act as central modulator of gastrointestinal motor functions at the level of the PVN via neuropeptide Y1‐ and CRF1 receptor‐dependent mechanisms.
Effect of Calcitonin Gene‐Related Peptide on Gonadotrophin‐Releasing Hormone mRNA Expression in GT1‐7 Cells
Authors: Kinsey‐Jones J. S. , Li X. F. , Bowe J. E. , Brain S. D. , Lightman S. L. , O'Byrne K. T. 
Published: August 2005

AbstractRecent evidence has shown calcitonin gene‐related peptide (CGRP) to be a key mediator of stress‐induced suppression of the gonadotrophin‐releasing hormone (GnRH) pulse generator, although little is known about the neural pathways involved. In the present study, we investigated the potential direct action of CGRP on GnRH neurones using GT1‐7 cells, an established GnRH cell line. First, we detected expression of the CGRP receptor subunits, calcitonin receptor‐like receptor and receptor activity‐modifying protein‐1 in the GT1‐7 cells by reverse transcriptase‐polymerase chain reaction. Second, we have shown that CGRP inhibits GnRH mRNA expression in the GT1‐7 cells, which was effectively reversed by the CGRP receptor antagonist, CGRP8‐37. These results suggest that CGRP down regulates expression of GnRH mRNA, via CGRP receptors in the GT1‐7 cell, thus implying that a potential direct action of CGRP may mediate a suppressive effect on the GnRH neural network.
Cannabinoids Modulate Synaptic Activity in the Rat Supraoptic Nucleus
Authors: Soya A. , Serino R. , Fujihara H. , Onaka T. , Ozaki Y. , Saito T. , Nakamura J. , Ueta Y. 
Published: August 2005

AbstractIn the present study, we investigated the effects of the cannabinoid receptor agonist CP55,940 on excitatory and inhibitory synaptic transmission in the rat supraoptic nucleus. Whole‐cell patch clamp recordings were performed on supraoptic neurones in in vitro brain slice preparations. CP55,940 significantly reduced the frequency of spontaneous excitatory and inhibitory postsynaptic currents in a concentration‐dependent manner. These changes were potently reversed by the CB1 receptor antagonist AM251. The results indicate that cannabinoids modulate the activity of magnocellular neurosecretory neurones by presynaptic inhibition of both excitatory and inhibitory synaptic transmission.
Morphological Characterization of Receptor Activator of NFκB Ligand (RANKL) and IL‐1β Expression in Rodent Collagen‐Induced Arthritis
Authors: Weiss R. J. , Harris H. Erlandsson , Wick M. C. , Wretenberg P. , Stark A. , Palmblad K. 
Published: August 2005

AbstractBone loss represents a major unsolved problem in rheumatoid arthritis (RA). The receptor activator of nuclear factor‐κB ligand (RANKL) is essential for the development and activation of osteoclasts, which are key mediators of bone erosions. This study was performed to determine temporal and spatial expression of RANKL compared with the potentially destructive cytokine interleukin‐1β (IL‐1β), related to progression of synovitis and joint destruction in collagen‐induced arthritis (CIA), a model of RA. CIA was induced in dark agouti (DA) rats, and tissue specimens were obtained for immunohistochemical analyses at various time points before and after disease onset. Arthritis was monitored visually, and joint pathology was examined histologically. No disease‐preceding expression of RANKL was detected. However, a marked increase of both RANKL‐ and IL‐1β‐expressing cells correlated with the progression of synovial inflammation and clinical disease severity. Abundant and concomitant expression of these cytokines was detected at sites of bone erosion, where a co‐localization by osteoclast‐like multinuclear tartrate‐resistant acid phosphatase (TRAP)+ cells was noted. In contrast to the paucity of RANKL expression in cartilage, an abundant expression of IL‐1β was demonstrated, particularly in superficial cartilage layers. These data support the hypothesis that RANKL and IL‐1β are central contributors to joint destruction in CIA.
Whole influenza virus vaccine is more immunogenic than split influenza virus vaccine and induces primarily an IgG2a response in BALB/cmice
Authors: Hovden A.‐O. , Cox R. J. , Haaheim L. R. 
Published: August 2005

AbstractThe aim of this study was to compare the kinetics and the magnitude of the humoral immune response to two different influenza vaccine formulations, whole and split virus vaccines. BALB/cmice were immunized intramuscularly with one or two doses (3 weeks apart) of 7.5, 15 or 30 µg of haemagglutinin of monovalent A/Panama/2007/99 (H3N2) split or whole virus vaccine. The two vaccine formulations induced similar kinetics of the antibody‐secreting cells response; however, differences in the magnitude were observed in the spleen and bone marrow. Vaccination with whole virus vaccine generally elicited a quicker and higher neutralizing antibody response, particularly after the first dose of vaccine. The two vaccine formulations gave different immunoglobulin G (IgG) subclass profiles. Split virus vaccine stimulated both IgG1 and IgG2a antibodies suggestive of mixed T‐helper 1 (Th1) and Th2 response, whereas whole virus vaccine induced mainly an IgG2a antibody response, which is indicative of a dominant Th1 response. The increased immunogenicity of whole virus vaccine in a naïve population could reduce the vaccine concentration needed to provide protective immunity.
Enhanced Maturation and Functional Capacity of Dendritic Cells Induced by Mannosylated L2 Domain of ErbB2 Receptor
Authors: Zhong G. , Wang J. , Xu M. , Xie Z. , Yu M. , Wang J. , Zhou T. , Gong W. , Sun Y. , Hu M. , Zhang X. , Shen B. , Guo N. 
Published: August 2005

AbstractThe nature of antigens and functional state of dendritic cells (DC) are important in antigen presentation. The ability of DC for the induction of T‐cell responses is promoted by maturation. It has been confirmed that mannose receptors mediate highly efficient endocytosis and presentation of mannosylated proteins. In the present study, L2 domain of ErbB2 ectodomain was expressed in Escherichia coli, purified and mannosylated. The maturation and functional capacity of DC induced by mannosylated L2 (mL2) protein were investigated. The results showed that L2 protein could induce DC maturation, which was accompanied by elevated expression of MHC and co‐stimulatory molecules. The effect of mL2 protein on DC maturation was more remarkable than that of non‐mL2 proteins. Uptake of mL2 antigens by DC was more efficient. Furthermore, the T cells can be stimulated to proliferate in vitro and secrete Th1 and Th2 cytokines. Higher levels of both IFN‐γ and IL‐10 were detected from the T cells stimulated by mL2‐pulsed DC, suggesting a concurrent activation of CD4+ and CD8+ T cells. The results demonstrated that L2 domain of ErbB2 receptor is an immunodominant molecule. The mL2 domain of ErbB2 can induce an enhanced maturation and functional capacity of DC. It may become an effective strategy to induce anti‐ErbB2 response.