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Showing papers by "University of Bern published in 1987"


Journal ArticleDOI
TL;DR: It is suggested that “periimplantitis” be regarded as a site specific infection which yields many features in common with chronic adult periodontitis.
Abstract: In this study the microbiota associated with oral endosteal titanium hollow cylinder implants (ITI) was studied using microscopic, immunochemical and cultural methods. Samples from 5 edentulous patients with successfully incorporated implants serving as abutments for overdentures for more than one year were compared with samples from 7 patients with clinically failing implants. Unsuccessful sites were characterized by pocket probing depths of 6 mm or more, suppuration and visible loss of alveolar bone around the implant as visualized on radiographs. These sites harbored a complex microbiota with a large proportion of Gram-negative anaerobic rods. Black-pigmented Bacteroides and Fusobacterium spp. were regularly found. Spirochetes, fusiform bacteria as well as motile and curved rods were a common feature in the darkfield microscopic specimens of these sites. Control sites in the same patients harbored small amounts of bacteria. The predominant morphotype was coccoid cells. Spirochetes were not present, fusiform bacteria, motile and curved rods were found infrequently and in low numbers. The microbiota in control sites in unsuccessful patients and in site in successful patients were very similar. On the basis of these results, it is suggested that “periimplantitis” be regarded as a site specific infection which yields many features in common with chronic adult periodontitis.

1,783 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that for small quark masses, low temperatures and large volumes, the main features of the QCD partition function can be predicted on the basis of chiral symmetry.

532 citations


Journal ArticleDOI
TL;DR: Human blood mononuclear cells were cultured for 24 h in the presence of LPS, and a monocyte-derived neutrophil-activating factor (NAF) was purified to apparent homogeneity from the conditioned media.

491 citations


Journal ArticleDOI
01 Jan 1987
TL;DR: In this article, applications of the interaction of microwaves with the natural snow cover are discussed. But the authors do not consider the effects of microwave technology on the natural vegetation in their work.
Abstract: (1987). Applications of the interaction of microwaves with the natural snow cover. Remote Sensing Reviews: Vol. 2, No. 2, pp. 259-387.

395 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that if the quark masses are very small, the correlation length becomes larger than the size of the box, and that the QCD partition function reduces to a standard integral over the flavour group.

393 citations


Journal ArticleDOI
04 Feb 1987-Tellus B
TL;DR: In this article, deconvolution of the CO 2 record yields a cumulative non-fossil production of about 90 to 150 Gt C until 1980, of which more than 50% were released prior to 1900.
Abstract: Measurements on air trapped in old polar ice have revealed that the pre-industrial atmosphere contained 280 ppm of CO 2 and that δ I3 C of atmospheric CO 2 decreased by about 1.1 ‰, until 1980. These measurements show that considerable amounts of non-fossil CO 2 must have already been emitted into the atmosphere in the 19th century. Quantitative estimates of the emission rates were performed by deconvolving the CO 2 and δ I3 C records, using models of the global carbon cycle (box-diffusion and outcrop-diffusion ocean, four-box biosphere). Depending on the structure of the ocean submodel, deconvolution of the CO 2 record yields a cumulative non-fossil production of about 90 to 150 Gt C until 1980, of which more than 50% were released prior to 1900. According to the model results, the net non-fossil production rate was roughly constant in the 19th and the first part of the 20th century. In the past 30 years, smaller values are obtained (0-0.9 Gt C yr -1 ) which are at the lower limit or below current ecological estimates for deforestation and land use (1.6 ± 0.8 Gt C yr -l ). The difference might possibly be due to other sinks, e.g., stimulation of plant productivity by the enhanced CO 2 Concentration. Calculated 13 C and 14 C time histories agree well with the observed changes. While the change of the atmospheric CO 2 concentration reflects more the cumulative carbon release, the isotope concentrations are more sensitive to short-term changes of the emission rate. The reason is that the oceanic uptake capacity is smaller for excess CO 2 by the buffer factor of ~10 than for an isotopic perturbation. DOI: 10.1111/j.1600-0889.1987.tb00278.x

337 citations


Journal ArticleDOI
TL;DR: The morphology of postnatal human lung development and growth has been investigated by light and by scanning and transmission electron microscopy in seven children dying from non-respiratory causes and aged between 26 days and 64 months as mentioned in this paper.

328 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the propagation of ultrashort (0.83 ps), intense dye laser pulses through a single-mode optical fiber and found that the parameters of this pulse closely correspond to those of the fundamental soliton solution of the nonlinear Schroedinger equation.
Abstract: The propagation of ultrashort (0.83 ps), intense dye laser pulses through a single-mode optical fiber is investigated. The input wavelength is tuned in the vicinity of the zero dispersion wavelength of the fiber. Although the input power is sufficient to generate solitons of up to the tenth order we do not observe the formation of high-order solitons. Instead, the input pulse breaks up temporally and spectrally after an initial stage of narrowing, and an ultrashort Stokes pulse is formed which shifts continuously to lower frequencies with increasing fiber length. The parameters of this pulse closely correspond to those of the fundamental soliton solution of the nonlinear Schroedinger equation. Using fiber lengths from a few meters up to 1 km the resulting pulse durations lie between 55 and 410 fs and the corresponding wavelengths between 1.36 and 1.54 μm. Numerical simulations solving a modified nonlinear Schroedinger equation including higher order dispersion and the Raman effect are in good agreement with the experimental results. It is shown that the principal soliton pulse shaping mechanisms are pulse narrowing and the soliton self-frequency shift.

259 citations


Journal ArticleDOI
TL;DR: In this paper, the authors report on new measurements made over the frequency range from 2 to 100 GHz by a resonator method (2-10 GHz) and a radiometer method (10-100 GHz).
Abstract: So far, knowledge about the dielectric properties, especially the loss factor, of ice at microwave frequencies has been unsatisfactory. In this work the authors report on new measurements made over the frequency range from 2 to 100 GHz by a resonator method (2-10 GHz) and a radiometer method (10-100 GHz). Measurements were made with pure and with slightly saline (10 to 13 p.p.m.) ice. The results agree with the assumption of a single minimum of the dielectric loss at 2 to 4 GHz. For pure ice the data are a natural link between the measurements of Westphal made below 1 GHz and the far-infrared spectrum. The influence of small impurities on the dielectric loss is compared with the behaviour of sea ice, and it is found that the same linear relationship with salinity can be applied to both cases.

257 citations


Journal ArticleDOI
TL;DR: In this article, the authors observed that the presence of silicate species modifies the morphology of both reaction products and showed that at high levels of silicates, goethite crystals adopt a pseudohexagonal shape.
Abstract: The transformation of ferrihydrite to goethite and/or hematite in alkaline media is strongly retarded by the presence of silicate species. These species probably stabilize ferrihydrite by adsorbing on the particles of ferrihydrite and linking them into an immobile network. At concentrations low enough for the transformation to proceed, silicate species promote the formation of hematite and hinder the nucleation of goethite. The presence of silicate species modifies the morphology of both reaction products. Hematite forms ellipsoidal single crystals, commonly displaying outgrowths of goethite. Silicate species in solution appear to enhance the development of the (021) faces of goethite, probably by preferential adsorption on these faces; at high levels of silicate species, goethite crystals adopt a pseudohexagonal habit. This morphology has not been observed previously for goethite.

225 citations


Journal ArticleDOI
TL;DR: Evaluated longitudinally the changes occurring in the subgingival microbiota in children following the placement of orthodontic bands in the absence of a prophylactic oral hygiene program, an increase in pocket probing depth was observed following tooth-banding, while the P1I and GI scores remained unaffected.
Abstract: The purpose of this clinical and microbiological study was to evaluate longitudinally the changes occurring in the subgingival microbiota in children following the placement of orthodontic bands in the absence of a prophylactic oral hygiene program. A total of 12 children in the age between 10 and 15 years were selected for the study. The experimental group (E) consisted of 6 subjects scheduled for orthodontic treatment including the placement of fixed appliances. They were seen 1 week before and just prior to the placement of orthodontic bands. The control group (C) involved 6 children in the maintenance phase of orthodontic therapy in which removable retainers were used. All subjects were examined at 3-5 week intervals for a period of 4 months. At each examination, microbiological subgingival plaque samples were collected by means of sterile paper points. Plaque and gingival index scores as well as pocket probing depth at the site of sampling were determined. The microbiological samples were processed using continuous anaerobic culturing techniques and were plated on non-selective and selective media. Differential counts and biochemical characterization of isolates were performed according to the methods described by Kornman and Loesche. Following tooth-banding, an increase in pocket probing depth was observed, while the P1I and GI scores remained unaffected. A statistically significant increase from baseline values (p less than 0.05) was found for the %s of black-pigmented bacteroides, the B. intermedius and A. odontolyticus species, concomitantly with a decrease of the anaerobe/facultative bacteria ratio in the experimental, but not the control sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Journal ArticleDOI
01 Jul 1987-Spine
TL;DR: Since 1984, 30 patients with burst fractures of the lower thoracic and lumbar spine were treated with AO internal spinal skeletal fixation system, which provided sufficient rigid fixation for rapid postoperative mobilization in a light external orthosis.
Abstract: Since 1984, 30 patients with burst fractures of the lower thoracic and lumbar spine were treated with AO internal spinal skeletal fixation system. All patients in this series had a minimum follow-up of 12 months. This new instrumentation is a posterior intrapedicular system developed by Dick in 1982. It allows stable fixation that is limited only to adjacent spinal segments. The internal fixator permits reduction in all three planes. Independently, it is possible to add distraction or compression to the involved segments. It also is able to reduce effectively the "middle column" which is thought to be accomplished by "ligamentotaxis." In this series there were 16 neurologically intact patients and 14 with partial or complete neurologic injury. There were two minor instrumentation loosenings early in the series. Most patients in this series had a near-anatomic reduction of all three columns in the involved segment. It was also possible to re-establish the normal lordosis of the lumbar spine. The device provided sufficient rigid fixation for rapid postoperative mobilization in a light external orthosis.

Journal ArticleDOI
TL;DR: A simple scoring system (“Manchester Score”) using these variables was established and shows little loss of information compared to the Cox analysis and distinguishes 3 prognostic groups, the best of which contains all long‐term survivors, whereas the bad prognostic group contains no patient surviving longer than one year.
Abstract: In 407 patients with small-cell lung cancer (SCLC), 61 pretreatment variables were evaluated in a Cox multiple regression analysis to assess their prognostic value. All patients received short-term intensive regimens (cyclophosphamide, etoposide and methotrexate or ifosfamide and etoposide, both followed by thoracic irradiation if complete response was noted). Lactate dehydrogenase (p = 0.0001), tumour stage (p = 0.0001), serum sodium (p = 0.0009), pretreatment Karnofsky performance score (p = 0.0121), alkaline phosphatase (p = 0.0186) and serum bicarbonate (p = 0.0321) were the important prognostic factors. Once these variables were taken into account no other variable provided additional prognostic information. A simple scoring system (“Manchester Score”) using these variables was established and shows little loss of information compared to the Cox analysis. The score distinguishes 3 prognostic groups, the best of which contains all long-term survivors, whereas the bad prognostic group contains no patient surviving longer than one year. The scoring system may help to design new treatment strategies and may also facilitate the comparison of different studies.

Journal Article
TL;DR: Sonographic reassessment of masses with patterns suggesting benign disease may be an alternative to immediate surgical exploration in a selected population (ie, those with poor surgical risk) and requires further improvement.

Journal ArticleDOI
01 Oct 1987-Spine
TL;DR: Nine healthy adults and 43 patients with cervical spine injury were examined by using functional CT scanning to measure axial rotation and found hypomobility and surgical stabilization of rotatory instability could be considered as a possible therapeutic procedure.
Abstract: Nine healthy adults and 43 patients with cervical spine injury were examined by using functional (computerized tomography) CT scanning. The ranges of axial rotation at the levels occiput C0-C1, C1-C2, and C2-C3 were measured. A rotation at C0-C1 greater than 8 degrees; at C1-C2, 56 degrees; or a right-left difference C0-C1 greater than 5 degrees and C1-2 greater than 8 degrees indicates hypermobility. A rotation at segment C1-C2 of less than 28 degrees indicates hypomobility. Surgical stabilization of rotatory instability could be considered as a possible therapeutic procedure.

Journal ArticleDOI
TL;DR: The present results demonstrate the important contribution of the extracellular resistance to electrotonic interaction and propagation in densely packed myocardial tissue and changes in perfusion pressure are associated with changes in extracllular resistance, probably as a consequence of changes in intravascular volume.
Abstract: 1. Right ventricular rabbit papillary muscles were arterially perfused with a mixture of Tyrode solution, bovine erythrocytes, dextran and albumin. In the recording chamber, they were surrounded by a H2O-saturated atmosphere of O2 and CO2 which served as an electrical insulator. 2. Conduction velocity and passive electrical properties were determined from intra- and extracellular potentials measured during excitation and during flow of subthreshold current. 3. The propagation of the action potential was linear along the muscle at a velocity of 55.6 cm/s. The extracellular wave-front voltage was 51.5 mV. 4. The following values for passive cable properties were obtained: (i) a ratio of extra- to intracellular longitudinal resistance of 1.2; (ii) an extracellular specific resistance (Ro) of 63 omega cm; (iii) an intracellular specific resistance (Ri) of 166 omega cm; (iv) a space constant lambda of 0.357 mm; (v) a membrane time constant tau of 2.57 ms. The space constant lambda* recalculated for zero extracellular resistance was 0.528 mm. 5. Arresting perfusion with drop of perfusion pressure was associated with an immediate increase of the extracellular longitudinal resistance by 35% and a decrease of conduction velocity by 13%. 6. The present results demonstrate the important contribution of the extracellular resistance to electrotonic interaction and propagation in densely packed myocardial tissue. Moreover, changes in perfusion pressure are associated with changes in extracellular resistance, probably as a consequence of changes in intravascular volume.

Journal ArticleDOI
TL;DR: The sterol-like fungal metabolite wortmannin and a number of natural and chemically-derived analogues were found to block the induction of the respiratory burst during phagocytosis and chemical derivation showed that a furane structure between ring A and B with adjacent carbonyl functions is essential for activity.

Journal ArticleDOI
P Grolimund1, Rolf W. Seiler1, R Aaslid1, P Huber1, H. R. Zurbruegg1 
01 Nov 1987-Stroke
TL;DR: The transcranial Doppler method appeared very promising for detection of lesions of the intracranial arteries although the number of such cases with angiographic verification was limited in the present series.
Abstract: Results from 1,039 combined cervical and transcranial Doppler examinations are reported. Satisfactory transcranial signals were not found in 2.7% of the cases. Compared with angiography, the accuracy of transcranial criteria in assessing collateral flow over the circle of Willis was 94 and 88% for anterior and posterior circulation, respectively. The method also appeared very promising for detection of lesions of the intracranial arteries although the number of such cases with angiographic verification was limited in the present series. Arterial narrowing due to cerebral vasospasm was diagnosed with a sensitivity of 80%. In patients with ruptured intracranial aneurysms, an incidence of 93% arterial narrowing in basal cerebral arteries was found. Patients with subarachnoid hemorrhage and no aneurysm on angiography also showed arterial narrowing with an incidence of 56%. It was possible to monitor the time course and severity of cerebral vasospasm. Arteriovenous malformations were characterized by Doppler findings of high velocities and low pulsatilities. These lesions were diagnosed with an accuracy of 95%.

Journal ArticleDOI
TL;DR: How the athletic species combine variations in structural and functional design parameters of the lungs, the heart, the muscle microvasculature and their mitochondria to adapt the respiratory system to the needs of a 2.5-fold higher level of aerobic performance capacity is determined.

Journal Article
01 Jan 1987-Bone
TL;DR: This paper reviews the mechanisms of action of the bisphosphonates, a new class of recently developed drugs that are characterized by a P-C-P bond and are thus analogs of pyrophosphate and in vitro inhibit both crystal formation and dissolution.

Journal ArticleDOI
TL;DR: Serial use of quantitative liver tests allows prediction of time of death from cirrhosis in this model.


Journal ArticleDOI
TL;DR: The onset of fMLP-stimulated H2O2 generation was detectable by chemiluminescence within 2 s of stimulation (as opposed to more than double this time by fluorometry), showing that high sensitivity is an important consideration in evaluating respiratory burst kinetics.

Journal ArticleDOI
E Sigel1
TL;DR: The Xenopus oocyte represents a useful system for the study of the expression of channels induced by foreign mRNA, for the characterization of their single‐channel behaviour and for the investigation of the action of pharmacologically active substances on these channels.
Abstract: 1. The properties of fast transient Na channels induced in the Xenopus laevis oocyte plasma membrane after injection of the oocyte with foreign messenger ribonucleic acid (mRNA) were investigated with the whole-cell voltage clamp and with the patch-clamp technique. 2. The time course of expression and the effect of the metabolic inhibitors actinomycin D and tunicamycin were studied. The rate of channel insertion reached a maximum only about 3 days after injection with mRNA and corresponded to the incorporation of 20 active channels/s, into a single oocyte. When applied intracellularly tunicamycin blocked the appearance of active channels nearly completely while actinomycin D added to the medium had no effect. 3. The whole-cell currents showed activation and inactivation properties reminiscent of skeletal muscle Na+ currents. The maximal peak current amplitude was 6 microA. Tetrodotoxin blocked the observed transient inward current. 50% inhibition was observed at 10 nM concentration. Veratridine depressed inactivation of the current and led to prolonged tail currents. 4. After removal of the surrounding layers of the oocyte tight seals were obtained with a patch-clamp electrode pushed on the surface membrane. Single-channel currents endogenous to the oocyte and Na+-channel currents induced by injected mRNA could be recorded. The single-channel slope conductance of the latter was 12-15 pS. Two different types of kinetic behaviour were evident from an analysis of single-channel currents and ensemble average currents. One type showed fast inactivation (tau less than 1 ms) and brief channel openings (less than 1 ms) whereas the second type was characterized by slower inactivation and a bursting behaviour. 5. When veratridine (75 microM) was present in the pipette solution the single-channel behaviour was modified in a complex manner. In addition to the channel openings with normal conductance a second open state was observed with a slope conductance of 3.5 pS. This second type of channel opening could still be recorded after return to the holding potential. Its final closure followed an exponential time course with a constant time constant of 0.5 s at -100 mV. These events probably underlie the tail currents in the whole-cell configuration. 6. The Xenopus oocyte represents a useful system for the study of the expression of channels induced by foreign mRNA, for the characterization of their single-channel behaviour and for the investigation of the action of pharmacologically active substances on these channels. This system may prove useful for the study of channels that are not accessible to patch-clamp experiments 'in situ'.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the 10Be half-life of the ORNL-MASTER solution using liquid scintillation counting and obtained a new value of (1.51 ± 0.06) Ma for the 10 Be halflife, which is in good agreement with the previously reported values but is almost three times more accurate.
Abstract: Absolute AMS-measurements of 10Be require reliable standards for calibration. Among the existing standards, rather large differences have been observed. These differences were found partially to be due to the different half-life values which were assumed. Also for comparison of AMS-data with activity measurements, it is necessary to know the 10Be half-life as precisely as possible. Starting with 5 ml of the standardized ORNL-MASTER solution, a working solution with a well-defined 10Be content was prepared. Its specific activity was determined by liquid scintillation counting. This measurement yielded a new value of (1.51 ± 0.06) Ma for the 10 Be half-life, which is in good agreement with the previously reported values but is almost three times more accurate. Two independent dilution series produced new AMS-standards with 10Be/9Be-ratios of the order of 10−10 and 10−11. These standards were measured at the ETH/SIN-AMS-facility with high accuracy and are compared with other available 10 Be-standards.

Journal ArticleDOI
TL;DR: The geometry and morphometry of intraacinar airways in rat and rabbit lungs were studied and the mean longitudinal pathway length--that is, the distance from the initial acinar segment to the terminal sacs--was found to depend on the cube root of the acinar volume in both species.
Abstract: The geometry and morphometry of intraacinar airways in rat and rabbit lungs were studied from silicone rubber casts. Acini, defined as the complex of alveolated airways distal to the "terminal" bronchiole, were trimmed off the bronchial tree. In both species, the acinar volume followed a log-normal distribution over a range in size of one order of magnitude. At an inflation level of 60% total lung capacity, their mean volume was 1.86 mm3 in the rat and 3.46 mm3 in the rabbit. On a representative sample of acini of different volumes, the branching pattern was characterized as irregular dichotomy, and the segment length and inner and outer diameters were measured. The average acinus had a mean of six generations in the rat and seven in the rabbit. Both showed a decrease in segment length and inner diameter with each generation. The mean longitudinal pathway length--that is, the distance from the initial acinar segment to the terminal sacs--was found to depend on the cube root of the acinar volume in both species. It was calculated at 1.46 and 1.95 mm for rat and rabbit, respectively.

Journal ArticleDOI
Sidney Shaw1, Peter Weidmann, J Hodler, A Zimmermann, A Paternostro 
TL;DR: The results show that a 4-h intrarenal infusion of alpha-hANP after renal ischemia can preserve glomerular filtration rate and reduce renal tissue damage.
Abstract: Because of its ability to increase glomerular filtration, antagonize the actions of vasoconstrictors, and produce vasodilation, alpha human atrial natriuretic peptide (alpha-hANP) was evaluated for its potentially beneficial effects in experimental ischemic renal failure induced by 45-60 min of renal artery occlusion in bilaterally or unilaterally renally intact Sprague-Dawley rats. After ischemia, a 4-h intrarenal infusion of alpha-hANP restored 14C-inulin clearances in bilaterally and unilaterally intact animals from 0.05 +/- 0.006 and 0.05 +/- 0.01 ml/min per 100 g to 0.314 +/- 0.04 and 0.25 +/- 0.01 ml/min per 100 g, respectively (P less than 0.001, n = 8), compared with normal values of 0.49 +/- 0.023 ml/min per 100 g. Histologically, there was a progressive decrease in medullary hyperemia and prevention of intratubular cell shedding and granulocyte margination as a result of the 4-h alpha-hANP infusion such that after 24 and 48 h the histological appearance of the tissue was essentially normal. The results show that a 4-h intrarenal infusion of alpha-hANP after renal ischemia can preserve glomerular filtration rate and reduce renal tissue damage.

Journal ArticleDOI
TL;DR: γ-Seminoprotein (γ-SM) is a glycoprotein from human seminal plasma, which was isolated in highly purified form by ion-exchange chromatography on a Mono Q column as mentioned in this paper.
Abstract: γ-Seminoprotein (γ-SM), a glycoprotein from human seminal plasma, was isolated in highly purified form by ion-exchange chromatography on a Mono Q column. The main form, fraction M, was homogeneous by PAGE at pH 8.3 and by SDS-PAGE. The complete amino acid sequence of γ-SM was determined with the aid of fragments generated by cleavages with cyanogen bromide, clostripain, chymotrypsin and Staphylococcus aureus V8 protease. The fragments were aligned with overlapping sequences. The single polypeptide chain of γ-SM contains 237 amino acids with a calculated Mr of 26079. A single N-linked carbohydrate side chain is attached to Asn45. The complex structure of this oligosaccharide has been determined recently [van Halbeek H. et al. (1985) Biochem. Biophys. Res. Commun. 131, 507–514]. Sequence comparison with serine proteases shows a high degree of homology, especially with the kallikrein family. The residues in the vicinity of the active site of serine proteases are also highly conserved in γ-SM, indicating the participation of His41, Asp96 and Ser189 in its active site. γ-SM hydrolyzed M-casein with a pH optimum at 8.0, but failed to hydrolyze any of the synthetic substrates tested. This proteolytic activity could be inhibited with diisopropylfluorophosphate, phenylmethylsulfonyl fluoride, Zn2+ or Hg2+ ions.

Journal ArticleDOI
TL;DR: In this paper, a photochemical dissolution of goethite in acid/oxalate solution, Fe3+, Fe2+, and CO2 were released and towards the end of the reaction ferrous oxalate precipitated.
Abstract: During photochemical dissolution of goethite in acid/oxalate solution, Fe3+, Fe2+, and CO2 were released and towards the end of the reaction ferrous oxalate precipitated. The dissolution process involved an initial slow stage followed by a much faster reaction. The slow stage was eliminated by addition of 20 ppm Fe2+ to the system at the start of the reaction. The presence of this Fe2+ did not accelerate the secondary dissolution process. Both protons and oxalate ions appear to have been involved in the dissolution process. Dissolution was accelerated by an increase in oxalate concentration (from 0.0025 to 0.025 M) in the system and also depended on pH, reaching a maximum rate at pH 2.6. Highly substituted (15.9 mole % Al) goethite dissolved more slowly per unit area than unsubstituted goethite. Lepidocrocite (γ-FeOOH) dissolved faster than goethite. The first stage of the dissolution process probably proceeded by slow release of Fe3+ through complexation with oxalate adsorbed on the goethite surface. The faster, secondary step appears to have been a reductive dissolution reaction involving adsorbed ferrous oxalate.

Journal ArticleDOI
G.M. Shore1
TL;DR: The conformal anomaly in two-dimensional curved spacetime sigma models of the type relevant in string theory is investigated in this article, where an explicit formula for the anomaly is presented in terms of functional derivatives of the generating functional with respect to local, i.e. position-dependent, background fields, the coefficients involving the corresponding renormalization group beta functions.