bluuebunny/crossref_metadata_2025_split huggingface dataset:
X-Ray Powder Diffraction Studies on the Rehydration Properties of Beidellite
Authors: Kawano Motoharu , Tomita Katsutoshi 
Published: August 2006

AbstractThe rehydration properties of Ca-, Mg-, Na-, and K-saturated homoionic beidellites after heating at various temperatures were compared with those of montmorillonites. The behavior of interlayer Na+ during dehydration and rehydration was also investigated by means of one-dimensional Fourier analysis. The K- and Mg-saturated specimens exhibited fast and slow rehydration rates, respectively, during exposure to air of 50% RH after heating at 800°C. These homoionic specimens showed strong rehydration properties on saturation with deionized water after heating <900°C for 1 hr. On the basis of Fourier analysis, the interlayer cations appeared to have migrated into the hexagonal holes of SiO4 network on thermal dehydration, and the migrated cations returned to the interlayer space on rehydration. This behavior of the interlayer cations appears to have been strongly dependent on value of the octahedral negative charge and on the sizes of interlayer cations. The small octahedral negative charge of beidellite produced a weaker attractive electrostatic force between the octahedral sheets and the migrated interlayer cations. Therefore, the migrated interlayer cations in beidellite were easily extracted from the hexagonal holes, and rehydration was rapid. The small cation migrated easily into hexagonal holes and was fixed to the holes. On the contrary, large cations were probably difficult to fix and were easily extracted from the hexagonal holes. Consequently, the rehydration rate of K-saturated beidellite was fast, and that of Mg-saturated beidellite was slow.
Weathering of Granitic Muscovite to Kaolinite and Halloysite and of Plagioclase-Derived Kaolinite to Halloysite
Authors: Robertson Ian D. M. , Eggleton Richard A. 
Published: August 2006

AbstractWeathered perthite and mixed muscovite-kaolinite from a kaolinitic granite at Trial Hill in east Queensland and kaolinized sericitic alteration from a granite from the Ardlethan Tin Mine of New South Wales were examined by optical, scanning electron (SEM), and transmission electron microscopy (TEM) to determine the alteration process of muscovite to kaolinite and kaolinite to halloysite (7Å). Muscovite was found intimately interleaved with kaolinite in a variety of proportions on a sub-micrometer scale. The contact was generally parallel to the (001) layers of both minerals, and the thickness of the contact layer alternated between 10 and 7 Å over short distances. Where the kaolinite to muscovite contact was at an acute angle to the muscovite layers, a small angle existed between the layering of the two phases, consistent with a topotactic alteration of muscovite to kaolinite. One tetrahedral sheet in the muscovite appeared to have been removed over 50–100 Å, converting a 10-Å layer to a 7-Å layer. The mica near the contact with kaolinite was easily damaged in the electron beam and showed Al loss during analytical transmission electron microscopy; thus, H3O+ probably substituted for K+ in this transitional phase.An SEM examination of completely weathered plagioclase showed kaolinite plates having attached, parallel, polygonal rods of halloysite (7Å), which had planar sides and a central void, partly fused with the surfaces of the kaolinite crystals. TEM study showed that the kaolinite altered to halloysite, and that, where the kaolinite was partly altered to halloysite, a series of sharp kinks were present in the kaolinite plate in which alteration had occurred. These kinks were interspersed with linear kaolinite relics, 0.1–0.2 μm long, which appear to have provided local rigidity to the clay packet. Apparently, the altered clay first curled into loosely wound spirals, which ranged in cross-section from triangles to irregular octagons, with pentagons and hexagons being most common. The tendency to pentagons and hexagons compares well with a statistical study of the angles, which were most commonly grouped around 120°. As alteration of the kaolinite relics progressed, the linear parts of the spiral lost their rigidity and became circular or oval shaped. The long axis of the halloysite spirals was parallel to the X axis of the kaolinite. Halloysite spirals formed most readily if they had space to curl; if space was not available, the halloysite formed sheaves. Rare, thin layers of muscovite were present projecting through kaolinite into halloysite. Where muscovite relics reached open spaces, the 10-Å structure expanded to 14 Å.
Transformation of Akaganéite Into Goethite and Hematite in the Presence of Mn
Authors: Cornell R. M. , Giovanoli R. 
Published: August 2006

AbstractThe interaction of Mn and akaganéite in neutral to alkaline media has been investigated using X-ray powder diffraction and transmission electron microscopy. Akaganéite transformed into goethite and/or hematite, whereas Mn precipitated as hausmannite and birnessite at pH > 12 and as manganite at pH 7.5–8.5. Mn influenced the kinetics of the transformation of akaganéite: the rate-determining step, i.e., the dissolution of akaganéite, was retarded by adsorbed Mn species. Hematite formation was not suppressed. By catalyzing the air oxidation of adsorbed Mn(II), akaganéite promoted the formation of birnessite. Akaganéite did not retard recrystallization of the Mn phases. The incorporation of Mn in the structure of goethite formed in this system was negligible, and jacobsite (MnFe2O4) did not form. The formation of mixed Mn-Fe phases appeared to require a ratio of Mn2+: Fetotal > 0.02; this ratio was not achieved due to the oxidation of Mn2+ at the akaganéite surface.
Formation of Organic Derivatives of Boehmite by the Reaction of Gibbsite with Glycols and Aminoalcohols
Authors: Inoue Masashi , Tanino Hirokazu , Kondo Yasuhiko , Inui Tomoyuki 
Published: August 2006

AbstractThe reaction of gibbsite in various organic solvents at 250°–300°C under spontaneous vapor pressure of the solvents was examined. Glycols and aminoalcohols afforded the organic derivatives of boehmite in which one of the oxygen atoms of the glycol molecule or the alcoholic oxygen atom of aminoalcohol was incorporated into the boehmite layers. By increasing the molecular size of the solvent, the yield of the boehmite derivative decreased, and, at the same time, the basal spacing of the boehmite derivative increased. The product had a honeycomb texture on the surface of the particle, which suggests a dissolution-recrystallization mechanism for the formation of the boehmite derivatives. A hydroxyl group and a functional group, such as hydroxyl, methoxyl, or amino group having the ability to donate its lone pair electrons, were apparently necessary for the organic solvent molecules to form the boehmite derivative by this mechanism.
Interactions of Citric Acid and Synthetic Hydroxy-Aluminum Montmorillonite
Authors: Cambier P. , Sposito Garrison 
Published: August 2006

AbstractHydroxy-Al-montmorillonite was prepared by mixing Na-Wyoming montmorillonite with Al(OH)2.5 polycations and aging the mixture for 10 days. The reactions of this complex with citric acid at millimolar concentrations were investigated at different pHs for a 4-hr reaction time. The citrate sorption data, X-ray powder diffraction patterns of the montmorillonite adsorbent, and solubility products for Al(OH)3, estimated after computer speciation of the aqueous solution phase, suggested two reaction mechanisms, depending on pH. At 4 < pH < 5.5, the complex was stable, and only external hydroxy-Al polycations could react with citrate, yielding a sorption envelope characteristic of an acid having a low pKa. At higher pH, and particularly at pH > 7, the interlayer Al-polymers became accessible to the ligand and desorbed quickly from the montmorillonite basal planes to form a new, external, X-ray-amorphous solid phase with citrate. This reaction produced a large second peak in the sorption envelopes near pH 8, which was controlled by the increasingly negative surface charge at high pH and by the initial concentration of citric acid. This ligand accelerated, i.e., favored kinetically, the dissociation of adsorbed hydroxy-Al polymers from montmorillonite at pH > 7.
Preparation and Properties of Large-Pore La-Al-Pillared Montmorillonite
Authors: Sterte Johan 
Published: August 2006

AbstractLarge-pore La-Al-pillared montmorillonite was prepared by reacting montmorillonite with hydrothermally treated mixtures of aluminum chlorohydrate and lanthanum chloride. The large-pore La-Al-pillared montmorillonite is characterized by basal spacings of about 26 Å, surface areas of 300–500 mVg, and pore volumes in the range 0.2–0.3 cm2/g. Large-pore pillared montmorillonite products were obtained from solutions refluxed for >72 hr or treated in autoclaves at 120°–160°C for 12–96 hr. The most favorable pillaring solution for the production of large-pore La-Al-pillared montmorillonite had an OH/Al ratio of 2.5, a La:Al ratio of 1:5, and was 2.5 M with respect to Al. The elemental composition of large pore La-Al-pillared montmorillonite is similar to that of a conventional Al-pillared montmorillonite that has a basal spacing of about 19 Å. The 26-Å spacing is believed to be associated with the formation of large polymeric La-bearing Al-cations upon hydrothermal treatment of the solutions.
Interactions between Speed and Contrast Tuning in the Middle Temporal Area: Implications for the Neural Code for Speed
Authors: Krekelberg Bart , van Wezel Richard J. A. , Albright Thomas D. 
Published: August 2006

A car driving through the fog appears to move more slowly than one driving on a clear and sunny day. In the laboratory, this observation has been confirmed as a pronounced reduction of perceived speed caused by a reduction in contrast.We measured the influence of contrast on cells in the middle temporal area (MT) of the macaque, which has been hypothesized to underlie the perception of speed. The influence of contrast on the responsiveness and speed tuning of these cells was pervasive and highly regular. As expected, most cells responded less at low contrast. More importantly, the preferred speed of most cells shifted to lower speeds at lower contrasts. Moreover, approximately one-third of cells surprisingly responded more strongly to slow low-contrast stimuli than to slow high-contrast stimuli.Current models of speed perception suggest that each MT cell votes for its preferred speed, with a vote determined by its firing rate. We tested a number of these labeled-line models by entering the neural responses we recorded from MT and comparing the predictions of the models with the perceptual reports of human subjects and monkeys. Contrary to the perceptual reports, the labeled-line models predicted that perceived speed should increase when contrast is decreased. We therefore conclude that perceived speed is not based on a labeled-line interpretation of MT cells.
Comparing and Combining Effort and Catch Estimates from Aerial–Access Designs as Applied to a Large-Scale Angler Survey in the Delaware River
Authors: Vølstad Jon H. , Pollock Kenneth H. , Richkus William A. 
Published: August 2006

Abstract
We used probability-based aerial−access surveys to estimate effort, catch, and harvest of American shad Alosa sapidissima and striped bass Morone saxatilis by recreational anglers in the Delaware River and upper estuary in 2002. Sampling of anglers at access points and flights over the river were conducted weekly from mid-March through October. Daily flight times were randomly selected; probabilities were proportional to the observed distribution of daily angler effort in a prior aerial−access survey (random count). Additional experimental flights were scheduled to occur at the time of day with expected peak effort (maximum count). Effort estimates derived from these maximum counts were more precise than estimates derived from the random flights, but the maximum-count observations caused bias except when the daily count expansions were based on effort distributions from the concurrent access survey. The aerial and access surveys produced similar estimates of boat angler effort and little evidence of bias, but shore anglers were undercounted in the aerial survey. We maximized the precision and minimized bias in total effort estimates by combining the estimates of boat angler effort and shore angler access. An estimated sevenfold increase in the access survey sampling effort (at nearly five times the cost) would be required to achieve the same precision in the total effort estimate produced by the aerial–access survey. Effective stratification and the use of efficient model-based estimators helped us to achieve the target precision of 20% in relative standard error (RSE) for estimated recreational catch of American shad (mean = 26,885 fish; RSE = 16%) and striped bass (mean = 47,671 fish; RSE = 15%). A single access survey during the American shad run would have required a 10-fold increase in sampling effort to achieve the same precision in estimated catch at six times the cost of the complemented surveys.
Development of a Rapid Bioassessment Protocol for Sampling Fish in Large Prairie Rivers
Authors: Utrup Nicholas J. , Fisher William L. 
Published: August 2006

Abstract
We used seining and hoop netting to collect fish at 15 sites in five large prairie rivers in Oklahoma to (1) determine the amount of effort needed to detect the maximum number of species at a sample site and (2) examine the selectivity of fish species detected by the two gear types. Analysis of the similarities of the fish collected in six different habitat types identified two distinct habitat types based on fish species composition: shallow–backwater (SBW) habitat (depth ≤ 0.75 m) and deep–nonwadeable (DNW) habitat (depth &gt; 0.75 m). We estimated that between 6 and 10 (mean = 8) SBW habitats and between 1 and 6 (mean = 4) DNW habitats at each sample site were needed to obtain maximum species richness during a sampling event. The sampling distance needed to encounter the minimum number of habitats ranged from 400 to 1,600 m and averaged 887 m. Gear evaluation showed that seining captured more species per unit effort than hoop netting (3.6 and 1.4, respectively); however, hoop netting captured significantly larger fish (527 mm; P &lt; 0.001) than seining (42 mm). Based on these collections, we present recommendations for sampling fish assemblages in large prairie rivers in the southern Great Plains to aid in the rapid bioassessment and monitoring of fish assemblages in large prairie rivers.
Performance of Passive Integrated Transponder Tags and Radio Tags in Determining Dam Passage Behavior of Adult Chinook Salmon and Steelhead
Authors: Burke Brian J. , Jepson Michael A. 
Published: August 2006

Abstract
Passage of adult Pacific salmon Oncorhynchus spp. and steelhead O. mykiss at dams in the Columbia River basin has historically been determined by visual fish counts and radiotelemetry. Increasingly, however, passive integrated transponder (PIT) tags are being used for adult salmonid research and monitoring. Although both radiotelemetry and PIT tag technology provide accurate and cost-effective data under certain circumstances, neither alone meets all needs, and managers need to understand the strengths, weaknesses, and biases of each method. To evaluate the two tagging methods, we tagged over 3,200 adult Chinook salmon O. tshawytscha and steelhead during 2002 and 2003 with both a radio transmitter and a PIT tag as the fish migrated upstream past Bonneville Dam. We compared their performance in measuring upstream passage and fallback (i.e., downstream passage) behavior at each of four main-stem hydropower dams. Counts of fish passage at dams based on data from double-tagged fish were similar between methods (largest difference was 5.1%), but the two methods produced less consistent results for fallback behavior. Visual count escapement estimates based on PIT tags were 1% higher on average than those based on radio tags, suggesting there would be little impact on the management of salmonid populations with a switch from radiotelemetry to PIT tag systems as the primary data source. We also analyzed a broader group of PIT-tagged (but not radio-tagged) fish to simulate the analysis one could expect from PIT tag data without radiotelemetry validation. When compared with PIT tag data from double-tagged fish, data from the PIT tag-only fish showed slight differences in the timing of peak passage. These differences were due, at least in part, to the fact that the fish in each group comprised differing proportions of fish from multiple populations, highlighting the importance of having representative stocks of fish PIT-tagged as juveniles.
Effects of pesticides on soil invertebrates in model ecosystem and field studies: A review and comparison with laboratory toxicity data
Authors: Jänsch Stephan , Frampton Geoff K. , Römbke Jörg , van den Brink Paul J. , Scott-Fordsmand Janeck J. 
Published: August 2006

AbstractA systematic review was carried out to investigate the extent to which higher-tier (terrestrial model ecosystem [TME] and field) data regarding pesticide effects can be compared with laboratory toxicity data for soil invertebrates. Data in the public domain yielded 970 toxicity endpoint data sets, representing 71 pesticides and 42 soil invertebrate species or groups. For most pesticides, the most frequent effect class was for no observed effects, although relatively high numbers of pronounced and persistent effects occurred when Lumbricidae and Enchytraeidae were exposed to fungicides and when Lumbricidae, Collembola, and Arachnida were exposed to insecticides. No effects of fungicides on Arachnida, Formicidae, or Nematoda or of herbicides on Lumbricidae, Formicidae, or Nematoda were observed in any studies. For most pesticides, higher-tier no-observed-effect concentration or lowest-observed-effect concentration values cannot be determined because of a lack of information at low pesticide concentrations. Ten pesticides had sufficient laboratory data to enable the observed higher-tier effects to be compared with 5% hazardous concentrations (HC5) estimated from acute toxicity laboratory data (atrazine, carbendazim, chlorpyrifos, diazinon, dimethoate, γ-hexachlorocy-clohexane, lambda-cyhalothrin, parathion, pentachlorophenol, and propoxur). In eight cases, higher-tier effects concentrations were within or below the 90% confidence interval of the HC5. Good agreement exists between the results of TME and field tests for carbendazim, but insufficient information is available for a comparison between TME and field studies for other pesticides. Availability and characteristics (e.g., taxonomic composition and heterogeneity) of the higher-tier effects data are discussed in terms of possible developments in risk assessment procedures.
Error autocorrection in rational approximation and interval estimates. [A survey of results.]
Authors: Litvinov Grigori 
Published: August 2006

Abstract
The error autocorrection effect means that in a calculation all the intermediate errors compensate each other, so the final result is much more accurate than the intermediate results. In this case standard interval estimates (in the framework of interval analysis including the so-called a posteriori interval analysis of Yu. Matijasevich) are too pessimistic. We shall discuss a very strong form of the effect which appears in rational approximations to functions. The error autocorrection effect occurs in all efficient methods of rational approximation (e.g., best approxmations, Padé approximations, multipoint Padé approximations, linear and nonlinear Padé-Chebyshev approximations, etc.), where very significant errors in the approximant coefficients do not affect the accuracy of this approximant. The reason is that the errors in the coefficients of the rational approximant are not distributed in an arbitrary way, but form a collection of coefficients for a new rational approximant to the same approximated function. The understanding of this mechanism allows to decrease the approximation error by varying the approximation procedure depending on the form of the approximant. Results of computer experiments are presented. The effect of error autocorrection indicates that variations of an approximated function under some deformations of rather a general type may have little effect on the corresponding rational approximant viewed as a function (whereas the coefficients of the approximant can have very significant changes). Accordingly, while deforming a function for which good rational approximation is possible, the corresponding approximant’s error can rapidly increase, so the property of having good rational approximation is not stable under small deformations of the approximated functions. This property is “individual”, in the sense that it holds for specific functions.
Existence and nonexistence results for reaction-diffusion equations in product of cones
Authors: Hamidi Abdallah , Laptev Gennady 
Published: August 2006

Abstract
Problems of existence and nonexistence of global nontrivial solutions to quasilinear evolution differential inequalities in a product of cones are investigated. The proofs of the nonexistence results are based on the test-function method developed, for the case of the whole space, by Mitidieri, Pohozaev, Tesei and Véron. The existence result is established using the method of supersolutions.
Optimal cubature formulas in a reflexive Banach space
Authors: Vaskevich V. 
Published: August 2006

Abstract
Sequences of cubature formulas with a joint countable set of nodes are studied. Each cubature formula under consideration has only a finite number of nonzero weights. We call a sequence of such kind a multicubature formula. For a given reflexive Banach space it is shown that there is a unique optimal multicubature formula and the sequence of the norm of optimal error functionals is monotonically decreasing to 0 as the number of the formula nodes tends to infinity.
Representation-finite triangular algebras form an open scheme
Authors: Kasjan Stanisław 
Published: August 2006

Abstract
Let V be a valuation ring in an algebraically closed field K with the residue field R. Assume that A is a V-order such that the R-algebra Ā obtained from A by reduction modulo the radical of V is triangular and representation-finite. Then the K-algebra KA ≅ A ⊗V is again triangular and representation-finite. It follows by the van den Dries’s test that triangular representation-finite algebras form an open scheme.
On artin algebras with almost all indecomposable modules of projective or injective dimension at most one
Authors: Skowroński Andrzej 
Published: August 2006

Abstract
Let A be an artin algebra over a commutative artin ring R and ind A the category of indecomposable finitely generated right A-modules. Denote
$$\mathcal{L}_A$$
to be the full subcategory of ind A formed by the modules X whose all predecessors in ind A have projective dimension at most one, and by
$$\mathcal{R}_A$$
the full subcategory of ind A formed by the modules X whose all successors in ind A have injective dimension at most one. Recently, two classes of artin algebras A with
$$\mathcal{L}_A \cup \mathcal{R}_A$$
co-finite in ind A, quasi-tilted algebras and generalized double tilted algebras, have been extensively investigated. The aim of the paper is to show that these two classes of algebras exhaust the class of all artin algebras A for which
$$\mathcal{L}_A \cup \mathcal{R}_A$$
is co-finite in ind A, and derive some consequences.
On characterization of Poisson and Jacobi structures
Authors: Grabowski Janusz , Urbański Paweŀ 
Published: August 2006

Abstract
We characterize Poisson and Jacobi structures by means of complete lifts of the corresponding tensors: the lifts have to be related to canonical structures by morphisms of corresponding vector bundles. Similar results hold for generalized Poisson and Jacobi structures (canonical structures) associated with Lie algebroids and Jacobi algebroids.