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The flotation and adsorption behaviors of two quaternary ammonium collectors DTAC (dodecyl trimethyl ammonium chloride) and CTAC (cetyltrimethyl ammonium chloride) on diaspore and kaolinite were investigated in this work. The flotation recovery of diaspore increases with the increase of pH and the decrease of particle size, however, the situations for kaolinite are opposite. Furthermore, the influence of pH on flotation of kaolinite decreases with the decrease of particle size, and for the fine particles (undersize 0.045mm), the flotation recovery with CTAC which has a longer hydrocarbon chain and is believed to have a stronger collecting ability is lower than that with DTAC. The dramatic differences of the flotation behaviors between diaspore and kaolinite are correlated to the differences of their crystal structures. The morphologies of diaspore and kaolinite particles in different size were studied by SEM. The kaolinite particles have much larger specific surface areas (about 7 times) than the diaspore particles due to their layered structure. This leads to the differences of collector adsorption behaviors on kaolinite and diaspore and results in the different flotation behavior. [ABSTRACT FROM AUTHOR]

• Premise of the study: Variation in how seeds are dispersed in grasses is ecologically important, and selection for dispersal mechanisms has produced a great variety of dispersal structures (diaspores). Abscission ("shattering") is necessary in wild grasses, but its elimination by selection on nonshattering mutants was a key component of the domestication syndrome in cereal grasses. A key question is whether a common genetic pathway controls abscission in wild grasses, and, if so, what genes in that pathway may have been selected upon during domestication. We summarize morphological and genetic information on abscission zones and disarticulation patterns in grasses and identify hypotheses to test the likelihood of a common genetic pathway. • Methods: Morphological data on abscission zones for over 10000 species of grasses were tabulated and analyzed using a tribal phylogeny of the grasses. The genomic location of quantitative trait loci (QTLs) and orthologs of genes controlling shattering were compared across species to ascertain whether the same loci might control shattering in different grass lineages. • Results and conclusions: The simple trait of nonshattering is derived from a great diversity of shattering phenotypes. Several sets of QTLs from multiple species are syntenic yet many are not. Genes known to be involved in shattering in several species were found to have orthologs that sometimes colocalized with QTLs in different species, adding support to the hypothesis of retention of a common genetic pathway. These results are used to suggest a research plan that could test the common genetic pathway model more thoroughly. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum: Biological Sciences is the property of Universidade Estadual de Maringa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Seed morph, abiotic conditions and time of germination can affect plant fitness, but few studies have tested their combined effects on plasticity of plant life history traits. Thus, we tested the hypothesis that seed morph, germination season and watering regime influence phenotypic expression of post-germination life history traits in the diaspore-heteromorphic cold desert winter annual/spring ephemeral Diptychocarpus strictus. The two seed morphs were sown in watered and non-watered plots in late summer, and plants derived from them were watered or not-watered throughout the study. Seed morph did not affect phenology, growth and morphology, survival, dry mass accumulation and allocation or silique and seed production. Seeds in watered plots germinated in autumn (AW) and spring (SW) but only in spring for non-watered plots (SNW). A high percentage of AW, SW and SNW plants survived and reproduced, but flowering date and flowering period of autumn- vs. spring-germinated plants differed. Dry mass also differed with germination season/watering regime (AW > SW > SNW). Number of siliques and seeds increased with plant size (AW > SW > SNW), whereas percent dry mass allocated to reproduction was higher in small plants: SNW > SW > AW. Thus, although seed morph did not affect the expression of life history traits, germination season and watering regime significantly affected phenology, plant size and accumulation and allocation of biomass to reproduction. Flexibility throughout the life cycle of D. strictus is an adaptation to the variation in timing and amount of rainfall in its cold desert habitat. [ABSTRACT FROM AUTHOR]

Aim Ecological theory provides divergent views about how patterns of bryophyte occurrence are related from local to global scales. Here, I test the hypotheses that, based on the high dispersal capacity of bryophytes, patterns of occurrence are similar from local to global scales and independent of variation in diaspore and size traits, or alternatively that the patterns are dissimilar and depend on traits that are important for dispersal and competition. Location Global. Methods The occurrence patterns of 28 bryophyte species and their relationship to diaspore and shoot size were analysed for three study systems: (1) a local metacommunity on erratic calcareous boulders; (2) a regional study system in the biogeographical provinces of the Nordic countries; and (3) based on data available from the Global Biodiversity Information Facility ( GBIF). Results Contrary to expectations, bryophyte occurrence was not similar among local or global study systems, but regional occurrences matched both local and global occurrences. Contrary to neutral theoretical assumptions, the occurrences depended on traits. In the local metacommunity, there was a tendency towards a negative relationship between occurrence and diaspore size: small and large species tended to be rare, whereas species of intermediate size tended to be widespread. In the regional study system, species with large diaspores tended to be widespread, with frequency of occurrence positively correlated with shoot length. Main conclusions In contrast to patterns detected for micro-organisms, local and global frequencies of occurrence for bryophytes are not necessarily similar. However, occurrences at the regional scale may be useful for predicting both local and global occurrences. Links between species traits important for dispersal and competition on the one hand, and occurrences on the other, supports the utility of these traits for the analysis of distributions and questions the adequacy of assumptions of functional equivalence. [ABSTRACT FROM AUTHOR]

Results are presented for the cathodoluminescence (CL) probe of an environmental scanning electron microscopy (ESEM) with an energy-dispersive spectrometry analyzer (EDS), thermoluminescence (TL), thermo X-ray diffraction in situ (TXRD), and simultaneous differential thermal analysis and thermogravimetric analysis (DTA/TGA) techniques of gem-quality zultanite samples collected from the Muğla region of southwest Turkey. Micro-Raman measurements were also performed on different zultanite orientations and preheated aliquots to study the spectral phase transition diaspore-corundum also detected by the other thermal techniques in the 450°C–500°C thermal range. The thermal phenomena of TL are synchronous with this dehydroxylation process, involving consecutive breaking-linking bonds of Al-O, Cr-O, Fe-O, Al-OH, Cr-OH, and Fe-OH, including the formation of hydrolyzed ions such, andand redox reactions. Assuming that zultanite oxygen atoms are distributed as a hexagonal close packed layer, the experimental spectrum CL of zultanite is characteristic of the2E → 4A2transitions of substitutional Cr3+luminescent centers in positions of Al3+in sixfold coordination. [ABSTRACT FROM PUBLISHER]

Copyright of Revista Brasileira de Biociencias is the property of Revista Brasileira de Biociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Selective flocculation is a new method to solve the problem of China's bauxite de-silication besides flotation and reverse flotation. The method of selective flocculation of bauxite using hydrolyzed polyacrylamide as flocculant was experimented and evaluated. The results of diaspore and kaolinite single mineral settling tests show that the difference between settlement yield of kaolinite (settling 15 min) and diaspore (settling 3 min) increases from 16% to 60% by adding flocculant at pH=7. Results of selective flocculation experiment of bauxite show that the higher concentrate grade (65.75) and Al-Si ratio (7.34) could be obtained with sodium carbonate as dispersant compared with sodium hexametaphosphate; under the action of flocculating agent, the concentrate grade and Al-Si ratio increase to 67.99 and 9.01. These results could meet the requirements of Bayer production, and the simpler process was expected to cost far less than traditional flotation method and a promising de-silication method of bauxite. [ABSTRACT FROM AUTHOR]

Palm diaspores are reported to have various kinds of dormancy. However, (1) the embryo is underdeveloped; (2) the endocarp is water permeable; and (3) the diaspores take a long time to germinate. Thus, we conclude that the diaspores of the majority of palm species have morphophysiological dormancy (MPD). The ones that do not have MPD are morphologically dormant. [ABSTRACT FROM AUTHOR]

Thehigh temperature dissolution behavior of diaspore concentratewas measured in concentrated NaOH–NaAl(OH)4solutions.The dissolution rate of Al was greatly found to be enhanced by increasingNaOH concentration and temperature while decreased with addition ofAl(OH)3. The concentration of Si as the main impurity constantlydecreases with reaction time while the Fe is retained at a limitedlevel. The generalized rate law for mineral dissolution and precipitation,proposed by Lasaga (Lasaga, A. C. Kinetic Theory in the EarthScience; Princeton University Press: Princeton, NJ, USA,1998), was applied to model the kinetic behavior of Al on the basisof KSP(diaspore) and the activity coefficientsof related species in the solution. The resulting kinetic model wascapable of predicting the dissolution rate of Al in the Bayer liquor.The apparent activation energy of the dissolution reaction over thetemperature range from 473.2 to 543.2 K was estimated at 83 kJ·mol–1. [ABSTRACT FROM AUTHOR]

Many alpine bryophytes rely primarily if not exclusively on gametophytic fragments for reproduction. The dispersal role of these fragments, however, has not been adequately addressed. The objective of this study was to determine the extent to which fragments disperse on alpine summits and the reproductive viability of those fragments. Airborne diaspores were collected from early spring snow deposits in 2008, 2009, and 2010 from the summit of Mt. Marcy, and from summer propagule traps placed on the summits of Mt. Marcy and Algonquin Peak in 2009 and 2010. All fragments collected were identified to genus and/or species, when possible. To test for reproductive viability, fragments were grown in nutrient agar under ambient conditions for a period of 17 weeks. To detect the presence of spores, collected debris was surface sterilized and cultured on separate dishes containing nutrient agar. A total of 6130 gametophytic fragments, representing 26 species, were collected. Collections were dominated by individual leaves (65%) and leafy branch fragments (32%). Up to 20% of fragments collected were found to be viable, with the majority of growth originating from stem tissue. In contrast, spore production was found to be uncommon to rare. The results of this study provide evidence that Adirondack alpine bryophyte populations are maintained by the production and dissemination of gametophore fragments during both winter and summer months, with infrequent spore production events, perhaps episodically when weather conditions are most suitable. Data also suggest that vegetative propagules may travel longer distances on these summits than originally predicted. [ABSTRACT FROM AUTHOR]

[Display omitted] • Parnassos-Ghiona bauxites are rich in diaspore, deriving from the hypogene alteration of boehmite. • The Variani and Shila 1 deposits contain pyrite veins of epigenetic origin. • Both bauxitization and late epigenetic processes affected the geochemical features of the deposits. • Residual chromite and serpentine, and the Eu/Eu* ratio indicate ophiolites as possible parent rocks. The karst bauxites of the Parnassos-Ghiona Unit (Greece) are hosted within Upper Jurassic to Late Cretaceous carbonate rocks. Three bauxite horizons are intercalated within shallow water limestones. They are named B1, B2 and B3 from bottom to top. In this study we present the characteristics of the B3 horizon (Cenomanian-Turonian) sampled in Agia Anna, Variani and Shila 1 underground mines. The bauxite ore has a prevailing oolitic texture. Diaspore, boehmite, hematite and goethite are the major mineral components of the analyzed samples. Kaolinite, rutile and anatase are common minor phases. Pyrite occurs in a small number of samples. Ilmenite, rutile, chromite, zircon, baddeleyite and serpentine are common detrital minerals. Authigenic minor minerals are mostly represented by REE-phosphates, barite, and gypsum. The presence of pyrite and diaspore suggests that after a first stage of additional in situ weathering and bauxitization, the deposits were affected by early diagenetic reducing conditions (allowing the formation of pyrite) and significant diagenesis, resulting in diaspore formation. This three-stages genesis is reflected in complex correlations between major, minor and trace elements. The occurrence of detrital chromite and serpentine in the bauxite reflects mafic parental rocks. The mafic component likely originated from the ophiolite suites exposed in the vicinity of the Parnassos-Ghiona bauxites. [ABSTRACT FROM AUTHOR]

Froth flotation is an effective way to remove silicon and upgrade quality for diasporic bauxite, but its underlying mechanism on microscopic-scale mineral-bubble interaction was poorly understood. In this study, the collision processes of valuable mineral diaspore and main gangue mineral kaolinite with bubbles in collector solution of sodium oleate (NaOL) and dodecylamine hydrochloride (DAH) were recorded to analyze drainage rate of the liquid film (LF). The collector adsorption rate constant and the maximum value of LF drainage rate corresponding to each mineral before and after pretreatment by sodium hexametaphosphate (SHMP) were fitted by an established model. The results showed that NaOL and DAH both can promote LF drainage between the minerals and bubbles, the difference lies in the relationship of drainage rate in NaOL solution was diaspore greater than kaolinite and the opposite in DAH solution. Although SHMP pretreatment has depression effect on collector adsorption rate and LF drainage rate of both minerals in the two solutions, low-dose SHMP can effectively inhibit these parameters of kaolinite in NaOL solution, while effective inhibition for those of diaspore requires high-dose SHMP in DAH solution. The influence mechanism of SHMP in the two systems was further analyzed through active sites difference on minerals interfaces. The present work provides new insight into the underlying mechanism of direct and reverse flotation of diasporic bauxite from the perspective of LF drainage, which will facilitate the targeted development of new collectors in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

The diasporite-corundite rock transformation, which releases 6-8 wt% [H.sup.2]O in an average metabauxite, was studied experimentally. The results are compared with petrological observations on the island of Naxos (Greece), where the transformation occurred in metakarst bauxites during prograde regional metamorphism. Dehydration experiments were started with fine-grained natural diasporite embedded in marble. The samples were first annealed in the diaspore stability field, then slowly brought to the final pressure-temperature (P-T) conditions in the corundum field and kept there five to seven days. Overstepping the diaspore-corundum equilibrium by ~30[degrees]C at 8 kbar resulted in partial dehydration of diaspore. As with the corundum-in isograd on Naxos, the corundum grew preferentially along the bauxite-marble contact. Experiments at 17-40 kbar with T oversteps of 40-150[degrees]C resulted in complete diaspore breakdown. A high-porosity zone containing corundum and silicates developed along the bauxite-marble boundary, resulting from the solid volume decreases associated with the diaspore-corundum and decarbonation reactions. In nature, the marble similarly behaved as a barrier for liberated fluid, as indicated by coarse corundum-chloritoid segregations along metabauxite rims. In the 30-40 kbar experiments, the porous contact zone acted as fluid pathway, allowing partial dissolution of metabauxite. This demonstrates pronounced Al, Fe, and Ti mobility at high P and T of 600-800[degrees]C. Keywords: experimental metabauxite dehydration, diaspore, corundum, reaction-enhanced porosity, Al-mobility, Naxos.

Abstract: The coals of the South Walker Creek area in the northern Bowen Basin, with a vitrinite reflectance (Rvmax) of 1.7 to 1.95%, are among the highest rank coals currently mined in Australia. X-ray diffraction studies have identified an unusual mineral variation through the vertical sequence, with kaolinite-rich assemblages typical of other Australian coals at the top and bottom of the seam section and an illite–chlorite assemblage resembling a metamorphic association in the middle. Calcite and ankerite are also abundant in parts of the vertical sequence. Diaspore is abundant in the middle section of the seam in some areas, and paragonite, dickite or nacrite occurs in some locations as well. The distribution of the non-carbonate mineral assemblages cross-cuts the seam stratigraphy, and appears to be primarily controlled by faults and other structural features. Integration of the mineral distribution with optical and electron microscope data on the coal and non-coal bands, chemical data from coal ash analysis, and information from X-ray micro-tomography, suggests that the illite–chlorite and diaspore-bearing assemblages resulted from hydrothermal effects associated with fluid migration through the middle part of the coal seam. This is further confirmed by the development of metamorphic textures in a tonstein band, also altered to illite and chlorite, in the illite-rich part of the seam section, in contrast to a tonstein with more normal sedimentary textures and a kaolinite composition in the kaolinite-rich upper part of the seam. Detailed studies of cleat mineralisation suggest that fluids rich in Ca, Mg and Al were introduced relatively early in the seam's post-depositional history, associated with heat flow sufficient to alter the minerals in the coal and tonstein in the affected part of the seam section. The relatively uniform vitrinite reflectance profile observed through the seam section may indicate that the coal was already of high rank before the fluids were introduced, or that any localised heat effects on the organic matter associated with the changes in clay mineralogy were overprinted by subsequent wider-ranging rank advance processes. [Copyright &y& Elsevier]

The adsorption behaviors of three carboxyl hydroxamic acids on diaspore (010) and kaolinite (001) have been studied by density functional theory (DFT) and molecular dynamics (MD) method. The results indicated that carboxyl hydroxamic acids could adsorb on diaspore surface by ionic bonds and hydrogen bonds, and adsorb on kaolinite surface by hydrogen bonds. The models of carboxyl hydroxamic acids adsorbed on diaspore and kaolinite surfaces are proposed. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The soil seed bank and seed germination capacity of Poa annua in the vicinity of the Polish Antarctic Station (South Shetlands, Antarctica) were investigated. It was documented that annual bluegrass can reproduce sexually and produce a functional seed bank of close to 5000 seeds/m2 under maritime Antarctic conditions. Comparison of germination between Poa annua and two native plant species revealed that Poa annua seeds can germinate as fast or even faster than native species, and are more vigorous. Our studies show that in the Antarctic Poa annua can successfully reproduce sexually and produce fully developed, viable caryopses that are able to survive the maritime Antarctic winter, not only in a soil bank, but also directly in the previous year's inflorescences. [ABSTRACT FROM AUTHOR]

Abstract: Seed dispersal is hard to measure, and there is still a lack of knowledge about dispersal-related traits of plant species. Therefore, we developed D3, the Dispersal and Diaspore Database (available at www.seed-dispersal.info), which aims at simplifying ecological and evolutionary analyses by providing and integrating various items related to seed dispersal: empirical studies, functional traits, image analyses and ranking indices (quantifying the adaptation to dispersal modes). Currently, the database includes data for more than 5000 taxa and 33 items as well as digital images of diaspores (i.e. the dispersal units), seeds, fruits and infructescences. The included items cover common traits like diaspore mass, size, shape, terminal velocity and seed number per diaspore. Furthermore, we present newly or further developed items like ecomorphological categorizations of the diaspore and fruit as well as information from literature on prevailing dispersal modes. Finally, we introduce several items which are not covered in other databases yet: surface structure and form of the diaspore, the exposure of the diaspores in the infructescence and dispersal rankings. Dispersal rankings allow estimations of how well certain species are adapted to a specific dispersal mode in comparison to a larger species set. They are calculated as the percentile rank of an indicator of species’ dispersal potential in relation to a larger species set. Especially for the new and further developed items we outline the basic concepts in detail, describe the measurement and categorization methods and show how to interpret and integrate these data for single species as well as for larger species sets. Thereby, we calculate baseline statistics of seed dispersal of the Central European flora. We found that diaspores of 72% of the taxa show specializations related to long-distance dispersal, i.e. most often elongated appendages or nutrient-rich tissues. Diaspore masses, sizes and terminal velocities vary over several orders of magnitude and can be approximated by lognormal distributions. [Copyright &y& Elsevier]

Bauxite resources are widely spread in the earth. However, the effective utilization of this mineral is still under infant. The conventional collector for diaspore mineral is oleic acid. It has three main drawbacks which are highly insoluble, large dosages in bauxite flotation, and low selectivity, which hinder its application in industry. In this research, octylic hydroxamic acid was synthesized, and its collecting ability toward two major minerals in bauxite-diaspore and kaolinite was investigated. The collecting power of various reagents for diaspore are shown as follows: oleic acid

Many studies have compared diaspore dispersal ability and degree of dormancy in the two diaspores of dimorphic plant species. A primary goal of these studies was to determine if germination and dispersal characteristics of the two morphs fit within a high risk–low risk (bet-hedging) life-history strategy, i.e. high dispersal/low dormancy in one morph versus low dispersal/high dormancy in the other one. In a survey of 26 papers on 28 diaspore dimorphic species, we found that in 12 of the studies, which were published between 1978 and 2008, seeds were stored, and thus possibly afterripened, before they were tested for germination. The 14 papers that tested fresh seeds were published between 1963 and 2010. Failure to test fresh seeds likely resulted in misinterpretation of the diaspore dispersal/dormancy strategy in some of the species investigated. We conclude that it is imperative that fresh seeds be tested for germination in order to be certain that the correct relationship between dispersal and dormancy is elucidated, and thus that the correct interpretation is made concerning life-history strategy and bet-hedging, in dimorphic species. [ABSTRACT FROM AUTHOR]

In archaeobotanical studies, the taxonomic classification of diaspores has usually been done by simple morphological observation and visual comparison with ex situ collections of seeds, although the use of biometric indices has often proved to be a powerful approach in the taxonomic studies of the genus Vitis as well as for the species attribution of archaeological remains. Using image analysis techniques, seeds from two Sardinian archaeological sites, the pre-Nuragic and Nuragic complex of Sa Osa in central-western Sardinia, attested as the oldest Sardinian archaeological site with remains of Vitis seeds, and the Isola di Coltellazzo in southwest Sardinia, were selected and characterized on the basis of morphological features and Elliptic Fourier Descriptors. Moreover, seeds of five modern populations of V. vinifera ssp. sylvestris collected from southwest Sardinia and the seeds of 41 cultivars of V. vinifera ssp. vinifera mainly from southern and central-western Sardinia were also analysed by computer image analysis. The obtained data were used to implement a database of biometric parameters and to compare the unknown archaeological seeds with the characterized recent seeds, using Linear Discriminant Analysis. The similarity of the archaeological seeds to V. vinifera ssp. vinifera cultivars rather than to V. vinifera ssp. sylvestris populations could allow it to be stated that, between the Middle and Final Bronze Age, varieties very close to modern V. vinifera ssp. vinifera were already being used to produce wine and/or to be preserved for foodstuffs. Moreover, the better matching of the archaeological seeds to white grapes rather than black grape cultivars could indicate the origins of the traditional cultivation of white grapes in these regions of Sardinia. [ABSTRACT FROM AUTHOR]

Particularly well-known among the many impacts of the invasive annual grass downy brome ( Bromus tectorum, Poaceae) is its ability to alter fire cycles and increase in abundance after fire. However, little is known about how fire influences B. tectorum dispersal. We quantified fire effects on B. tectorum dispersal using three recently burned areas in the western region of the Colorado Rocky Mountains by marking diaspores (seeds) with fluorescent powder, and then recovering them at night using ultraviolet lights. Diaspores were of two types: with and without sterile florets attached. We also characterized vegetation cover and near-surface wind speed in burned and unburned areas. Diaspores travelled much farther in burned areas than in nearby unburned areas (mean ± standard error at the end of the experiment: 209 ± 16 cm and 38 ± 1 cm, respectively; maximal distance at the end of the experiment: 2,274 cm and 150 cm, respectively), indicating an increase in dispersal distance after fire. Diaspores with sterile florets attached dispersed longer distances than those without sterile florets (mean ± standard error at the end of the experiment: 141 ± 14 cm and 88 ± 7 cm, respectively). Vegetation cover was lower and wind speeds were higher in the burned areas. Our results indicate that at least one of the mechanisms by which the spread of B. tectorum is promoted by fire is through increased seed dispersal distance. Preventing movement of seeds from nearby infestations into burned areas may help avoid the rapid population expansion often observed. [ABSTRACT FROM AUTHOR]

Abstract: The performance of 2-[tris(hyroxycarbamoyl)methyl] carboxylic acids on flotation separation of diaspore over kaolinite and illite was investigated by using flotation tests, and their collecting performance was clarified by using density functional theory (DFT) calculation and molecular dynamics (MD) simulation. The flotation results of single minerals indicate that by using THDA, THCA or THTA as collector under neutral condition, diaspore presents good flotability while kaolinite and illite exhibit poor flotabilities. Among the three collectors, THCA displays the greatest difference in the flotability between diaspore and aluminosilicate. The flotation results of the artificially mixed minerals show that under the condition of pH 7 and 2×10−4 mol/L THCA, the A/S value in the concentrate is greatly increased and the separation of diaspore over aluminosilicates is feasible by using THCA as collector. DFT calculations show that large negative charges are located at the O and N atoms in the polar group of these collectors and the O atoms have more negative charges than N atoms. By comparison THCA has the highest HOMO energy, resulting in the highest collecting efficiency. The adsorption of collector on mineral surface by MD method indicates that the combination processes of collectors with mineral crystal are exothermic, and THCA has the greatest difference in binding energy between diaspore and aluminosilicate. A good correlation was found between the theoretical calculations and the experimental results. As a whole, THCA is a better collector to float and separate diaspore over aluminosilicates. [Copyright &y& Elsevier]

Questions The highest species richness is usually expected at an intermediate stage of development since the last major disturbance event, but some studies have shown that ecosystem productivity and dispersal may modify this pattern, suggesting the need for further studies on the effects of productivity and dispersal on the dynamics of species richness through succession. In this study, we analysed aquatic plant species richness in relation to (1) succession stage, measured as numbers of years since the last disturbance that affected the ecosystems; (2) lake productivity, measured as the chlorophyll a concentration; and (3) connectivity to similar nearby ecosystems, a proxy for the potential input of diaspores. Location Shallow lakes of the Dombes region, France. Methods Every 5-7 yr these shallow lakes are emptied and left to dry out for 1 yr. These drought disturbances lead to complete destruction of the submerged aquatic plant communities. Sixty lakes arranged along a gradient of productivity were selected. The probability of diaspore input was considered to increase from upstream to downstream, as lakes are organized in hydrologically connected networks via ditches, through which the downstream lakes receive water from the upstream lakes. For each lake, the aquatic plant species richness (from systematic summer vegetation sampling), time since the last disturbance (last summer drying), productivity (estimated as chlorophyll a concentration) and probability of diaspore input (assessed from position in the network) were recorded. Results The aquatic plant species richness decreased with the time since the last disturbance for all of the lakes, but there was a significant interaction with the chlorophyll a concentration and position of the lake in the network. At the lowest ecosystem productivities, the relationship between successional stage and species richness was hump-shaped, whereas the species richness decreased with increasing time since the last disturbance when productivity increased. The lake's position in the network did not influence species richness during the first 2 yr after disturbance, but from year 3 and thereafter, lakes connected to high numbers of upstream lakes consistently exhibited decreased richness, contradicting the expected trend of increasing species richness with increasing diaspore inputs. Conclusions This study indicates that both ecosystem productivity and connectivity strongly affected the relationship between aquatic plant species richness and succession, and that these factors should be taken into account in further developments of the intermediate disturbance hypothesis. [ABSTRACT FROM AUTHOR]

Elaiosomes of myrmecochorous plant seeds are known to enhance the attraction of diaspore-dispersing ants by serving as a nutritional reward. However, it remained unclear which (nutritional) compounds affect diaspore preferences of ants. We hypothesized that apart from elaiosome/seed-size ratio, volume, and physical surface of diaspores, the quantity and the composition of fatty acids, amino acids, and sugars strongly influence the diaspore preferences of different species. Chemical (nutritional) profiles as well as structural properties of seeds with and without elaiosomes were analyzed and correlated with observed seed choice behavior of ants. Cafeteria experiments in the field confirmed the enhanced attractiveness of elaiosome-bearing seeds for all three ant species tested ( Lasius fuliginosus, Myrmica ruginodis, and Temnothorax nylanderi), although seeds lacking elaiosomes also were transported. In multiple-choice cafeteria experiments with simultaneously offered diaspores of 16 plant species with and without elaiosome and with highly varying structural and chemical properties, all three ant species showed distinct preferences for certain diaspore species. Correlation analyses confirmed that the presence of an elaiosome represents the crucial factor that favors ant diaspore dispersal. In addition, the composition and the content of free amino acids, and to varying degrees fatty acids, were found to significantly affect preferences of each ant species, whereas the effect of single fatty acids acting as chemical triggers for diaspore transport by ants, as supposed by several studies, was not confirmed. In conclusion, although at least some diaspore species lacking elaiosomes attract ants for diaspore removal services by presenting nutritional seed coats, the production of elaiosomes seems to provide a worthwhile investment. Elaiosomes ensure rapid diaspore detection and removal due to chemical cue compounds and by offering a highly nutritional food supply, probably fitting the nutritional demands of ants. [ABSTRACT FROM AUTHOR]

Background:Elaiosomes serve as a reward for seed-dispersing ants. The size of the elaiosome and the elaiosome–seed mass (ESM) ratio are expected to affect seed dispersal, whilst seed size affects the establishment of seedlings. Elaiosomes and seeds can undergo independent change, thus variation in these traits may arise through heterogeneous selection for seedling establishment and for dispersal. Only a few studies have examined intraspecific variation in these traits. Aims:The aim of this study was to determine if the ratio of elaiosome–seed mass was different in two co-occurring congeneric plant species (Corydalis intermediaandC. solida). Under the hypothesis that the ESM ratio affected diaspore attractiveness to ants, the allometric relationship between elaiosome and seed mass was used to infer how selection by ants may shape the diaspore. Methods:Seed and elaiosome mass were measured in fruits collected from central and marginal populations of the two plant species. The allometric relationship between seed and elaiosome mass was obtained using major axis regression. In situ cafeteria experiments estimated the removal rate of diaspores by ants. Results:Intra- and interspecific variation in diaspore traits were found. The selfingC. intermediaproduced heavier seeds and elaiosomes than the outcrossingC. solida. Ants removed more diaspores fromC. intermediawhere both species were present. A slope larger than one characterised the allometric relationship between elaiosome and seed mass in both species. This slope was twice as steep in the central populations ofC. intermediacompared to marginal ones. Conclusions:Results indicate that inC. intermediaelaiosome mass must increase more than proportionally with increasing seed mass for the diaspore to remain attractive to ants. The direction of interspecific differences suggests that a plant-mating system may affect selection for dispersal. [ABSTRACT FROM PUBLISHER]

The bauxites deposits of Kachchh area in Gujarat are investigated to characterize them based on mineralogical and petrographic studies. The major bauxitic mineral in these occurrences is gibbsite, with minor concentration of boehmite and diaspore. Apart from the bauxitic minerals, the other associate minerals are kaolin, calcite, alunite and the iron ore minerals such as hematite and goethite and titanium rich anatase. The iron ore minerals (hematite and goethite) are 10-50microns in size and are disseminated throughout the oolitic and pisolitic bauxitic minerals. At places the goethite exhibits colloform texture. The preservation of basaltic texture in some of the samples indicate that the insitu nature of these bauxites, which are formed by the alteration of calcic plagioclase from the parent basalt. Although, the basalt occurs as the main parent rock for these bauxites, the presence of calcite in some of the samples represent the possibility of having a limestone parent rock at least in some of the bauxite occurrences. [ABSTRACT FROM AUTHOR]

Aim To infer the most plausible explanations for the presence of 14 species of the Neotropical cucurbit genus Sicyos on the Hawaiian Islands, two on the Galápagos Islands, two in Australia, and one in New Zealand. Location Neotropics, the Hawaiian and Galápagos archipelagos, Australia and New Zealand. Methods We tested long-problematic generic boundaries in the tribe Sicyoeae and reconstructed the history of Sicyos using plastid and nuclear DNA sequences from 87 species (many with multiple accessions) representing the group's generic and geographic diversity. Maximum likelihood and Bayesian approaches were used to infer relationships, divergence times, biogeographic history and ancestral traits. Results Thirteen smaller genera, including Sechium, are embedded in Sicyos, which when re-circumscribed as a monophyletic group comprises 75 species. The 14 Hawaiian species of Sicyos descended from a single ancestor that arrived c. 3 million years ago (Ma), Galápagos was reached twice at c. 4.5 and 1 Ma, the species in Australia descended from a Neotropical ancestor ( c. 2 Ma), and New Zealand was reached from Australia. Time since arrival thus does not correlate with Sicyos species numbers on the two archipelagos. Main conclusions A plausible mechanism for the four trans-Pacific dispersal events is adherence to birds of the tiny hard fruit with retrorsely barbed spines found in those lineages that underwent long-distance migrations. The Hawaiian clade has lost these spines, resulting in a lower dispersal ability compared with the Galápagos and Australian lineages, and perhaps favouring allopatric speciation. [ABSTRACT FROM AUTHOR]

Abstract: Aluminum-hydroxide (boehmite)-rich Pennsylvanian coals of high volatile A bituminous rank were found previously in the Jungar Coalfield, Inner Mongolia, China. This paper reports new results on 48 bench samples of the CP2 coal from the adjacent Adaohai Mine, Daqingshan Coalfield, Inner Mongolia, and provides new insights into the origin and modes of occurrence of the minerals and elements present in the CP2 coal. Compared to the same coal in the adjacent mines, the CP2 coal in the Adaohai Mine has a higher rank (Ro, ran =1.58%), which is attributed to igneous intrusions during the Late Jurassic and Early Cretaceous Epochs. The proportion of inertinite (35.3%) in the coal is higher than that in other Late Paleozoic coals in northern China but lower than that in the Jungar coals. Minerals in the CP2 coal include diaspore, boehmite, gorceixite, calcite, dolomite, siderite, clay minerals (kaolinite and ammonian illite), and trace amounts of anatase, fluorapatite, quartz, and pyrite. Based on mineral proportions in the coal bench samples, the CP2 coal may be divided into four Zones (I to IV) from bottom to top. The major mineral in Zones I and IV is kaolinite. Zones II and III are mainly composed of ammonian illite, diaspore, boehmite, gorceixite, calcite, dolomite, and siderite. Diaspore-, boehmite-, and gorceixite-forming materials were derived from oxidized bauxite in the weathered crust of the Benxi Formation in the sediment-source region during peat accumulation. However, gorceixite may have formed earlier than diaspore; the diaspore was derived from gibbsite that was subjected to dehydration by the heat of the igneous intrusions. The ammonian illite may have been formed at a relatively high temperature by interaction of kaolinite with nitrogen released from the organic matter in the coal during metamorphism caused by the igneous intrusion. The calcite and dolomite occur as epigenetic cell- and fracture-fillings and were probably derived from the igneous fluids. Compared to the common Chinese and world coals, the CP2 coal is enriched in CaO (1.69%), MgO (0.32%), P2O5 (0.214%), F (207μg/g), Ga (16.3μg/g), Zr (446μg/g), Ba (276μg/g), Hg (0.33μg/g), and Th (12.4μg/g), but has a lower SiO2/Al2O3 ratio due to the higher proportions of diaspore, boehmite, and gorceixite in the coal. The F occurs mainly in gorceixite and fluorapatite. The major carriers of Ga are diaspore and kaolinite but not gorceixite. Barium mainly occurs in gorceixite and barite. Mercury was probably derived from the igneous intrusion and is distributed in both the organic matter and the minerals. The elements are classified into five associations by cluster analysis, Groups A, B, C, D, and E. Group A represents a REE-Be-Y-Se-Ga-Ge-Sc-In-Pb-Bi-Nb-Ta-TiO2-W-Hg-Sb-Zr-Hf-Th-U association. Most of the elements in Group A are lithophile elements that occur in aluminosilicate minerals. Group B (Sn-Te-Zn-Cd-V-As-Cr-Cu-Mo-Ni-Re) is weakly correlated with ash yield and is associated with unidentified trace sulfide minerals. Elements in Group C (Ad-Na2O-Al2O3-SiO2- Li-K2O-Rb-Cs-Tl association) probably occur in the clay minerals and diaspore. Group D consists of P2O5, Ba, F, Sr, S, and Cl, and with the exception of S, they occur in minerals (gorceixite and fluorapatite). Oxides of Fe2O3-MnO-CaO-MgO make up Group E and mainly occur in the carbonate minerals. The coals are enriched in light REEs and the LREEs–HREEs have been highly fractionated, with an average (La/Yb) N of 8.71. The heavy REEs in the coals have a stronger organic affinity than the LREEs. [Copyright &y& Elsevier]

Abstract: Novel chelating reagents containing mono-carboxyl and double-hydroxycarbamoyl group were designed and synthesized as collector, such as 3,3-bis(hydroxycarbamoyl) undecanoic acid (BHUA), 3,3-bis(hydroxycarbamoyl) tridecanoic acid (BHTA) and 3,3-bis(hydroxycarbamoyl) pentadecoic acid (BHPA). These collectors were investigated to float single minerals, artificially mixed minerals and real diasporic bauxite ore. The collecting performance on minerals was interpreted by means of adsorption amount measurement, X-ray photoelectron spectroscopy analysis, zeta potential measurement and density functional theory (DFT) calculation. The appropriate pH value for the diaspore flotation are close to neutral pH value at which diaspore presents quite good floatability while kaolinite and illite exhibit very poor floatability. The satisfactory results on the mass ratio of Al2O3 to SiO2 and the Al2O3 recovery were obtained for the flotation separation of artificially mixed minerals and diasporic bauxite using BHUA as collector, demonstrating the high selectivity of BHUA for the flotation separation of bauxite. The O atoms in these collectors possess more negative charges and more easily donate electrons than N atoms, and surface Al atoms on diaspore are more than those on aluminosilicate minerals, causing diaspore adsorbing reagent in larger amount than aluminosilicate minerals and resulting in high selectivity for minerals flotation. [Copyright &y& Elsevier]

A new isidiate, xanthone-producing species, Rinodina chrysidiata, is described and compared in detail with R. xanthophaea, a species with which it co-occurs in eastern Asia. The two species have an identical chemistry but are clearly separated by their differing lichenized diaspores, thallus morphology and ascospore type. [ABSTRACT FROM AUTHOR]

Vibrational properties of diaspore, α-AlOOH, have been re-investigated using room-temperature single-crystal Raman spectroscopy and low-temperature powder infrared (IR) transmission spectroscopy. First-principles harmonic calculations based on density functional theory provide a convincing assignment of the major Raman peaks and infrared absorption bands. The large width of the Raman band related to OH stretching modes is ascribed to mode-mode anharmonic coupling due to medium-strength H-bonding. Additional broadening in the powder IR spectrum arises from depolarization effects in powder particles. The temperature dependence of the IR spectrum provides a further insight into the anharmonic properties of diaspore. Based on their frequency and temperature behavior, narrow absorption features at ~2,000 cm and anti-resonance at ~2,966 cm in the IR spectrum are interpreted as overtones of fundamental bending bands. [ABSTRACT FROM AUTHOR]