Lycopodium Spores Research Articles

Monte Carlo Analysis of Polydisperse Microparticle Impacts with Surfaces

The Monte Carlo method was applied to an impact model to investigate the impact of polydisperse microparticles with surfaces. The Monte Carlo results were compared to experiments. Two different situations were examined: the normal (90°) impact of microspheres with a molecularly-smooth silicon surface, and the oblique ( < 90°) impact of microspheres with a Formica surface. In the former, the percentage of microspheres captured by the surface and the overall capture velocity distribution were determined given the statistical distribution of the microsphere diameters. In the latter, both the Formica surface roughness angles and the diameters of the microspheres were treated as statistical variables. The mean values of the Monte Carlo simulation of the coefficient of restitution and the impulse ratio were found to agree with the data at the 95% confidence level. Finally, this approach was applied to model the impact of Lycopodium spores with a Formica surface.

Lycopodium spore impacts onto surfaces

Experiments on oblique impact of Lycopodium spores with dry surfaces in the presence of adhesion were carried out. The experimental results are compared with those of stainless steel microsphere impact onto the same types of substrate surfaces. Three parameters are analyzed, the coefficient of restitution, the impulse ratio and the normalized kinetic energy loss and are used to represent the impact results. The comparisons show that the complex surface profile of a spore has a remarkable effect on impact response. The conjunction of the roughness of both the microparticle and the substrate make the impact mechanics even more complicated.

Liptinite in coal and oil source rocks in northern Thailand

Palynological study of northern Thailand coal and oil deposits indicates a similar palynological association to that of the Borneo region. Coal petrographic studies of these deposits show variations in the liptinite macerals, especially alginite types. The oldest of these coal and oil deposits, which are of Late Oligocene to Early Miocene age, are dominated by Botryococcus sp. or Botryococcus-related algae. Thick-walled lamaginites and spores and pollen of temperate affinity, are found in some areas. By contrast, thin-walled lamaginite is dominant in late Middle Miocene time. Resinite, suberinite, and cutinite are dominant in forest swamp coal deposits whereas alginite, cutinite and lycopodium spores are dominant in lacustrine environments. Exsudatinite is common even at early levels of maturation. These liptinite macerals can be major sources of oil and gas.

Genesis and environmental history of Lagoa Santa, southeastern Brazil

Geomorphologic studies and palynological analysis of a core in the middle of Lagoa Santa, a lake in central Brazil (19°38'S; 43°54'W), have provided palaeoenvironmental information on the region and lake history during the Holocene. Prior to 5300 yr BP there is no pollen record in the sediments. The presence of spores of Lycopodium and algae (Phase I) between c. 6100 and 5400 yr BP indicate a gradual increase of moisture in the ancient valley. Between c. 5400 and c. 4600 yr BP the records of pollen, spores and algae indicate the presence of an intermittent marsh on the valley floor (Phase IIA) and a climate drier than at present; Gramineae pollen dominates the assemblages, followed by Compositae and Portulacaceae. At approximately 4600 yr BP pollen grains are abundant, percentage of arboreal pollen increases and Lycopodium spores are replaced by fern spores of a moist environment; the marsh was replaced by a permanent lake (Phase IIB). An ancient landslide scar was probably active shortly before this time and started to deposit debris at the basin outlet causing the formation of the permanent lake that has existed since then. A mosaic of forests and ‘cerrado’ (savannah-like vegetation) covered the region around the lake and the climate was warm semi-humid, similar to the present. The abundant archaeological sites dating from c. 5000 yr BP are coeval with the formation of the lake and of the change towards a more humid phase. From c. 3000 yr BP to the present, changes in the percentage of arboreal pollen indicate small oscillations in precipitation. The uppermost 20 cm of the sediment contains oxidized clay mixed with the lake sediment. Nevertheless, the well-preserved palynomorphs show that the oxidized material was transported to the lake as a result of human activities around the basin. The depletion of Stryphnodendron spp. trees in recent last centuries confirms human disturbance of the natural ecosystems. In general terms, the climatic variations detected at Lagoa Santa during the Holocene are in accordance with those in other parts of central Brazil.

Quantitative spore colour measurement using colour image analysis

The colour changes that spores exhibit, with increasing depth of burial, are used as a thermal maturity indicator for evaluating hydrocarbon source rocks. Spore colour is determined visually leading to an intrinsic difficulty of unequivocally assessing and recording their colour. Quantitative scales using photometers are available, but are not widely applied. Colour Image Analysis (CIA) is presented here as an alternative method for the quantification of spore colour, through the use of Image Analysis software common in many laboratories. Using the RGB (red, green, blue) colour format, the colour of spores was determined. The material included a set of artificially heated Lycopodium spores and geological samples from a range of ages and geographical areas covering the entire maturity range. These data were then compared to samples from a well section of Carboniferous age which were `fully mature' to `post mature'. With increasing maturity the colour changes in spores and pollen define a consistent and reproducible trend on the red vs. green (pixel intensity) graph. Significantly all samples suites (experimental and natural) exhibit the same behaviour. Previous research [ Milton, (1993)Ph.D. thesis; Gutjahr, 1966 Leidse Geologische Medelingen, 38, 1–30] show a strong morphological control on colour, based on differences in wall thickness and original chemistry. However, if spores and pollen are chosen carefully i.e. avoiding taxon with cracks, folds, apertures and ornamentation, as well as those with exceptionally thin (bag-type) or thick exines, a good sample average can be made by measurement of 40–50 similar spore/pollen types. Specific points on the red vs. green colour graph coincide with significant chemical transformations and these coincide with the thermal cracking of the spore wall (spore oil window).

Characterization of chargeability of biological particulates by triboelectrification

Triboelectric chargeability of pecan pollen and lycopodium spores, using commercial Teflon and nylon chargers, has been investigated as reported in this paper. The charge-to-mass ratio of lycopodium, measured at different powder feed rates, i.e., 50-500 mg/s, indicated that both Teflon and nylon chargers increased particle charge by approximately elevenfold over background with Teflon charging particles positively to +11.06 mC/kg and nylon negatively to -11.52 mC/kg. Pecan pollen charge increased by approximately 11 times for Teflon charging positively to +7.59 mC/kg, and five times for nylon charging negatively to a value of -3.72 mC/kg. Pollen charging was not affected by carrier-air humidity in the range of 18.1%-47.6% relative humidity (RH) and at a temperature of 22.5/spl deg/C. Pollen chargeability by Teflon measured as a function of the duration of air flow over the charger surface indicated that triboelectric charging was not degraded, even by 3.5 h continuous flow of humid air (44.2% RH at 19.2/spl deg/C). Results indicate that tribocharging is a feasible method for imparting charge to pollen in electrostatic pollination technology currently under development.

Hazards of powdered surgical gloves

Surgical gloves were originally used to protect the operator from powerful antiseptic agents but by the turn of the century they were adopted as two-way barriers. To facilitate donning of the gloves, a powder-talcum or lycopodium (spores of the club moss)-was used. Because they induced foreign-body granulomas, starch powder was introduced in 1947. Initially it was thought to be inert, but reports of granulomas began to appear a few years later, to be followed by cases of starch-induced peritonitis and starch-powder granulomas mimicking peritoneal carcinomatosis, 1 Eur J Surg. 1997; 163 Google Scholar all of which may lead to formation of adhesions. Adhesions are the commonest cause of small-bowel obstruction in the west, whereas in developing countries it is most commonly due to a hernia, volvulus, or tuberculosis. Foreign particulate matter, such as lint and starch, has been identified by histological examination in animal and human adhesions. 1 Eur J Surg. 1997; 163 Google Scholar The proposed mechanisms for adhesion formation include the release of inflammatory mediators from activated macrophages and interference with the fibrinolytic pathway. 1 Eur J Surg. 1997; 163 Google Scholar

The use of particle monitoring in the performance optimisation of conventional clarification and filtration processes

The application of laser diffraction particle monitoring to the performance optimisation of a pilot clarifier and full-scale rapid gravity filters (RGF), operating on water supply works in Hampshire, is described. Furthermore the dosing of powdered activated carbon (PAC) into the works' clarifiers has been evaluated in terms of RGF performance. A costly proposal to install a third filter medium was subsequently abandoned when it was found that particle numbers in the filtered water were consistently below 1×102/ml. Various combinations and doses of coagulants and flocculant aids, shown to give optimum particulates removal during intensive jar testing trials, were transferred to the pilot clarifier. Particle monitoring enabled a more accurate derivation of suitable blanket chemistry and optimum blanket heights than turbidity changes. Raw water turbidities were 10-15 NTU at start-up with corresponding counts beyond the upper limit of the particle monitor. An on-line dilution system was developed to overcome this problem. Latex bead (4.33 μm) and Lycopodium spore (4-5 μm) suspensions (about 1 × 109 particles) were injected into the pilot clarifier to assess the removal efficiency of Cryptosporidium-sized particles. Reductions of about 1.7 log and 2.6 log were achieved for the beads and spores, respectively. Particle distributions of various PAC's and a bentonite were obtained in order to assess their potential effects on the coagulation process during clarification. Bentonite was also beneficial as an on-line means of checking particle monitor response and calibration. The works' filters achieved 1.5 to 2.0 log removals of 2-5 μm particles without media addition or operational changes. Combined clarification and filtration gave better particulates removal than two-stage microfiltration.

The preparation of testate amoebae (Protozoa: Rhizopoda) samples from peat

The analysis of testate amoebae (Protozoa: Rhizopoda) in peat is proving to be a useful new quantitat ive technique for assessing hydrological change on peatlands. Preparation experiments were carried out on peat extracted from Coom Rigg Moss, Northumberland, England, in order to assess the impact of different procedures on the concentration and species composition of the faunas. Five replicates of each of six samples were treated by different techniques and the testate amoebae counted together with 200 Lycopodium spores. All preparation procedures suitable for pollen extraction reduce the number of tests recorded by up to 80% and the number of taxa recorded by 60%. KOH digestion did not destroy tests but damaged them, making identification difficult, although it enabled extraction of a higher number of tests. A simple water-based prep aration, with sieving to remove coarse and fine detritus, appears to give the best results and is an improvement on earlier techniques in removing more extraneous material from the samples. Testate amoebae counts from samples prepared for pollen analysis must be viewed with extreme caution and are unrepresentative of the faunal content of the peat in both absolute and relative terms.

Simultaneous measurements of wire electrode surface contamination and corona discharge characteristics in an air-cleaning electrostatic precipitator

Contamination of the corona wire in a wire-to-plate type air-cleaning electrostatic precipitator is studied experimentally. In order to enhance the contamination of wire, air containing dust is directly supplied to a part of the wire electrode. Spores of Lycopodium and cigarette smoke particles are used as test dusts. Simultaneous measurements of wire electrode optical images and corona discharge modes are carried out during contamination processes. Results show that corona discharge modes and optical emission from the wire electrode change with time due to the surface contamination, in the case of cigarette smoke, after a time elapsed, streamer coronas appear due to the buildup of smoke particles on the wire surface. After the first streamer generation, the corona current fluctuates with time because the formation and diminution of the projections occur alternately at the different parts on the wire electrode surface.

The use of particle monitoring in the performance optimisation of conventional clarification and filtration processes

The application of laser diffraction particle monitoring to the performance optimisation of a pilot clarifier and full-scale rapid gravity filters (RGF), operating on water supply works in Hampshire, is described. Furthermore the dosing of powdered activated carbon (PAC) into the works' clarifiers has been evaluated in terms of RGF performance. A costly proposal to install a third filter medium was subsequently abandoned when it was found that particle numbers in the filtered water were consistently below 1 × 102ml.Various combinations and doses of coagulants and flocculant aids, shown to give optimum particulates removal during intensive jar testing trials, were transferred to the pilot clarifier. Particle monitoring enabled a more accurate derivation of suitable blanket chemistry and optimum blanket heights than turbidity changes Raw water turbidities were 10–15 NTU at start-up with corresponding counts beyond the upper limit of the particle monitor. An on-line dilution system was developed to overcome this problem. Latex bead (4.33 µm) and Lycopodium spore (4–5 µm) suspensions (about 1 × 109 particles) were injected into the pilot clarifier to assess the removal efficiency of Cryptosporidium-sized particles. Reductions of about 1.7 log and 2.6 log were achieved for the beads and spores, respectively. Particle distributions of various PAC's and a bentonite were obtained in order to assess their potential effects on the coagulation process during clarification. Bentonite was also beneficial as an on-line means of checking particle monitor response and calibration.The works' filters achieved 1.5 to 2.0 log removals of 2–5 µm particles without media addition or operational changes. Combined clarification and filtration gave better particulates removal than two-stage microfiltration.

On diatom concentrations in lake sediments: results from an inter-laboratory comparison and other tests performed on a uniform sample

The diatom concentration of a uniform lake sediment sample was estimated in 15 laboratories. Whilst 21 of 35 estimates were between 13 and 19 × 107 valves g-1, values ranged from 8.2 × 106 to 2.0 × 109 valves g-1. However, counts from replicate sediment digestions, replicate slide preparations from a single digested slurry, and multiple counts from an individual slide all yielded internally consistent results, with acceptably low coefficients of variation (±4.5–6.3%). Without greater efforts towards harmonization, for example by calibrating techniques to a standard of known concentration, reported diatom concentration values, as well as derived data such as diatom accumulation rates, are not directly comparable between most laboratories. This sharply contrasts the strong reproducibility of diatom relative frequency data. A calibration exercise, using the Eucalyptus pollen spike technique to estimate a known concentration of Lycopodium spores, demonstrates that this method performs best when approximately equal proportions of microfossils and introduced markers are counted.

Corroded exines from Havinga's leaf mold experiment. SEM

Abstract Representative types of exine corrosion, seen on scanning electron micrographs, are illustrated from a leaf mold sample from the corrosion experiment of Havinga (1964). This work complements earlier transmission electron microscopy of the same sample (Rowley et al., 1990). Corroded areas are among the most dramatic indicators and products of exine destruction in samples of pollen and spores from Havinga's leaf mold material. Severely corroded regions, as seen using the secondary emission mode of the SEM, were most often found on exines with a continuous tectum (Myrica, Betulaceae, Corylaceae, Ulmus), but they also occurred to some degree in Fagus and on spores of Lycopodium. In taxa having pollen with a more or less continuous tectum the surface of the tectum was not destroyed but instead became depressed to the level of the floor of corroded areas. This “sunken tectum”; aspect of corrosion results from tunneling within the tectum without destruction of the surface. Muri of reticulated exines showed little indication of corrosion. Muri of Lycopodium, considered by Havinga as the most resistant exine in his experiment, were, however, often seen to be somewhat corroded and in some spores severely so. Fractures or tears, common to exines of many of the 19 taxa in Havinga's material, are illustrated for Fraxinus, Fagus, Quercus, Tilia, Pinus, and Lycopodium. Isolated sectors fractured from some taxa, e.g., Pinus and Tilia, are identifiable, but others are difficult to identify. In Pinus, where a portion of a sacculus was broken off, the surface of the foot layer showed hemispheroidal unit‐structures. Examples of folding and collapse were especially prominent in Taxus, Juniperus, Salix and Acer. Exines of these taxa were extremely difficult to recognize as pollen grain exines under oil immersion or with moderate SEM magnifications, although at higher magnifications exine structural details were seen to be intact. Small pit‐like circular holes were frequent on exines of Myrica and other betuloid grains, Fagus, Acer, Polypodium, and Lycopodium. These small holes may be of special interest since in Lycopodium they have been reported following abiological experiments.

Substructure of spore and pollen grain exines inLycopodium, Alnus, Betula, FagusandRhododendron

Abstract We have used atomic force microscopy and scanning tunnelling microscopy to extract new information about the substructure of the Alnus, Betula, Fagus, Lycopodium and Rhododendron pollen grain exine. Our scans of exines using atomic force microscopy and scanning tunnelling microscopy reveal somewhat similar substructures for Lycopodium spores and pollen of Alnus, Betula, Fagus and Rhododendron. They show various levels of alignment and clustering of substructure components. Except for Alnus, which showed polygonal clustering of spheroids and weak alignment, there is pronounced alignment of helical units. In Betula, Fagus, Lycopodium and Rhododendron the subunits appear to be helical or perhaps consisting of elongated spheroids, these spheroids are however arranged in a way that suggest that they are part of a helical structure. The diameter of these helical subunits range from 10–15 nm in Fagus, 20–25 nm in Lycopodium, 35–90 nm in Rhododendron up to 70–120 nm in Betula. Our preparations graded from intact or fractured fresh pollen to pollen that was acetolyzed, chemically fixed and epoxy resin embedded. While our knowledge of the exact radial/lateral orientation of most of our scans is less than perfect there were in all cases substructures or cross connections of exine units. We found results from scanning and transmission electron microscopy to be helpful in understanding images from Atomic Force- and Scanning Tunnelling Microscopy.

The variability in settling velocities of some pollen and spores

Abstract The settling velocity in still air of natural and dyed spores and pollen of several species was measured using the method of McCubbin and was found to be as follows (in cm s-1): black spruce (Picea mariana), 3.19; jack pine (Pinus banksiana), 2.53; Lycopodium, 2.31; dyed Lycopodium, 2.15; oil palm (Elaeis guineensis), 3.00; dyed oil palm, 2.16 and corn(Zea Mays), 30.95. The percentage of clustered spores and pollen was taken into account but was not found to significantly affect settling velocity except in the case of dyed oil palm. Comparisons of the measured settling velocities of clustred grains were made with the model of Ferrandino and Aylor. This was found to be accurate in general, but tended to over-estimate the settling velocity of clumped spores of Lycopodium and of dyed pollen of oil palm.

Inlet characteristics of bioaerosol samplers

The inlet sampling characteristics of several commercial bioaerosol samplers operating in indoor and outdoor environments have been analyzed by use of available and newly developed equations for sampling efficiency. With a focus on the physical aspects of sampling efficiency, the aspiration and transmission efficiencies have been calculated for the bioaerosol particle size range 1–30 μm, which represents single bacteria, bacteria aggregates, bacteria carrying particles, fungal spores, yeast, and pollen. Under certain sampling conditions, the bioaerosol concentration was found to be significantly over- or underestimated. At wind velocities between 0 and 500 cm s −1, calculations show that the AGI-30 would sample 1–10 μm particles with an inlet sampling efficiency of 20–100%. The entrance efficiency of the 6-stage Andersen viable sampler is 90–150% when sampling isoaxially with respect to horizontal aerosol flows, and 8–100% when oriented vertically at a right angle to the horizontal aerosol flow. For the Burkard portable air sampler, an even wider range of deviation may occur. The bioaerosol samplers used for large particles such as pollen are even less accurate: e.g. 10 times the ambient concentration of Lycopodium spores has been calculated to be aspirated by the Lanzoni sampler when operated at 0.5 1 min −1 facing the wind at wind velocity of about 500 cm s −1. The actual bioaerosol concentration can be calculated from the measured data by use of the indicated procedures. The sampling efficiency graphs presented can be used to bracket the sampling conditions that enable the investigator to avoid or minimize significant sampling biases for each sampler. The findings can also be used for the design of new samplers or for improving commercially available samplers.

Wind Tunnel Experiments of Large Particle Reentrainment-Deposition and Development of Large Particle Scaling Parameters

Reentrainment-deposition characteristics of lycopodium spores, timothy pollen, glass microballoons, glass spheres, and nickel spheres were examined in a series of wind tunnel experiments. Particle diameter varied from 18 to 34 (μm, and particle density varied from 1.0 to 8.9 g cm−3. Adhesion force distribution of each particle type was determined using the centrifuge method, and the force required to remove 50% of the particles had a range of more than an order of magnitude with lycopodium requiring the smallest force and glass spheres requiring the largest. The mean flow speed required to reentrain 50% of each particle type had a range of more than a factor of two with the same ordering from smallest speed to largest as found for adhesion force with the exception of nickel spheres, which required the second largest wind speed and the second smallest adhesion force for 50% removal. Threshold reentrainment flow speed, and distance traveled in a single reentrainment-deposition cycle were also examined for e...

Influence of application rates of bee-collected pollen on the fruit size of kiwifruit

Abstract Pollen, from pellets gathered by bees, was used to pollinate kiwifruit flowers artificially. Pollen was applied at a number of rates after suspending in an aqueous medium or mixing with one of three different diluents to get a powder formulation. Resulting fruit size was less at lower rates of pollen application. At such low rates (generally < 1.0 mg/flower), a linear relationship was detected between pollen application rate and final fruit size, in some seasons. Some powder formulations (e.g., that using Lycopodium spores) seemed less effective than the aqueous suspension. However, the best formulation for pollination of kiwifruit was made with an inert powder. This formulation effectively set fruit at rates of pollen as low as 0.037 mg/flower, although at this rate fruit size was reduced as a result of inadequate seed set.

Experimental Evidence of the Importance of Rebound in Net Deposition of Particles

Experiments were carried out in a low-speed wind tunnel to examine the processes of ideal deposition, net deposition, rebound, and reentrainment for large particles (lycopodium spores and ragweed pollen) using leaf surfaces (American elm and tulip poplar). Ideal deposition velocity was found to be linearly proportional to wind speed above a threshold level; below this level it was approximately the settling velocity. Net deposition velocity was close to the ideal deposition velocity at low speeds, but at higher speeds became significantly less than ideal deposition velocity because of rebound and reentrainment. Rebound appears to be more important than reentrainment at speeds above 3 m / s, but at low speeds reentrainment may be more important than rebound, although weak.

Quantitative spore colour

Spores exhibit changes in colour with increasing depth of burial; these changes have found wide application for thermal maturity determination in hydrocarbon source rocks. At present colours are determined visually. Here the application of the Commission Internationale de l’Eclairage colour system to the measurement of spores is described such that colour can be defined by the chromaticity co-ordinates ( x, y ) and the luminance ( L ) which define a colour solid. The colour changes seen in spores with increasing burial define a maturation pathway in this colour solid which shows two distinct trends. The first is a well-defined progressive colour change to a cusp at which a broad spread of colours from yellow to brown occur in a single sample. This is the interval over which hydrocarbons are generated and which is clearly defined by these colour differences. The second trend is through a series of brown colours with an increasing lack of sensitivity of the spores to colour changes. These changes are calibrated to vitrinite reflectivity. The data and conclusions are amplified and supported through changes in colour, chemistry and exine reflectivity in artificially matured Lycopodium spores. Comparisons are made with existing qualitative spore colour scales. The implications for maturation determination are that spore colour is a good thermal maturity index for the interval prior to oil generation and that it is suitable for quantitative modelling studies. It demonstrates the interval of oil generation at the cusp but after this point it becomes inaccurate and inferior to other methods such as vitrinite reflectivity.