Plastic Cylinder Research Articles

Canine collars: an investigation of collar type and the forces applied to a simulated neck model

BackgroundDog collars have the potential to cause harm when the dog pulls on the lead. This study aimed to determine the effects of collar type and force applied using the...

Enhanced relativistic electron beams intensity with self-generated resistive magnetic field

Active control of laser-produced relativistic electron beams (REB) transport is crucial for the success of the fast isochoric heating, which requires efficient energy transfer from REB to a small pre-compressed plasma core. In general, the laser-produced REB has a large divergence angle, thus only a small portion of REB interacts with the small core. We observed experimentally that the REB can be guided to a small area by using a resistive plastic cylinder buried in a conductive aluminum base. A two-dimensional hybrid numerical simulation shows that REB is confined in the plastic cylinder by a magnetic field generated spontaneously at the boundary between the resistive plastic and conductive aluminum.

Investigating feasibility of use of bio-sand filters for household water treatment in Epworth, Zimbabwe

This study investigated the feasibility of using bio-sand filters for household water treatment as an option to improve drinking water quality at household level. Drinking water from hand-dug shallow wells (depth <10m) was analyzed for pH, turbidity, chloride, nitrates, Electrical Conductivity (EC), Dissolved Oxygen (DO) and faecal coliforms. Three laboratory pilot water plants each comprising of a 90 mm diameter and 800 mm deep plastic cylinder with three different combinations of filter media (BSF1, BSF2 and BSF3) were set up. BSF1 comprised of sand only, BSF2 contained sand and a 50 mm thick layer of iron and sand mixture and BSF3 comprised of sand and a 100 mm thick layer of iron and sand mixture. The filters were fed with 1.5 litres of well water daily and composite samples of influent and effluent were collected for analysis daily for four weeks. The average values of the parameters for the raw well water used for the pilot plants were 6.75 (pH), 32.5 NTU (turbidity), 126 mg/L (chloride), 15 mg/L (nitrates), 303 μS/cm (EC), 2.2 mg/L(DO) and 1521 cfu/100 mL (faecal coliforms). There were significant differences (p > 0.05) between influent and effluent parameters for all three filters. The concentration of iron in the effluent was less than 0.03 mg/L for all filters. After four weeks, the bacterial removal efficiencies were 94.8%, 99.2% and 99.5% for BSF1, BSF2 and BSF3, respectively. The bio-sand filters modified with iron and sand mixture (BSF2 and BSF3) had a higher efficiency in reducing bacteria compared to the sand only filter (BSF1). Chemical dosage will be required to further improve the water quality.

Effect of Surface Treatment With Er:YAG and CO2 Lasers on Shear Bond Strength of Polyether Ether Ketone to Composite Resin Veneers.

Introduction: Polyether ether ketone (PEEK) has low surface energy and high resistance to chemical surface treatments. Therefore, different surface treatments such as laser conditioning should be investigated. There is a gap of information regarding the efficacy of laser irradiation in the surface treatment of PEEK, and the efficacy of several laser types needs to be evaluated for this purpose. This study aimed to assess the effect of surface treatment with erbium-doped yttrium aluminum garnet (Er:YAG) and carbon dioxide (CO2) lasers on shear bond strength (SBS) of PEEK to composite resin veneers. Methods: In this experimental study, 60 rectangular-shaped PEEK samples (7 x 7 x 2 mm) were used. The samples were mounted in auto-polymerizing acrylic resin in such a way that only one surface measuring 7x7 mm remained exposed. The samples were then randomly divided into 3 groups (n=20) of control, Er:YAG laser surface treatment (Power=1.5 W, energy density=119.42 J/cm2 , irradiation time=20 s) and CO2 laser surface treatment (Power=4 W, energy density=159.22 J/cm2 , irradiation time=50 s). The bonding agent and PEEK opaque were applied on the surface of samples and they were veneered with a composite resin using a hollow plastic cylinder with an internal diameter of 4 mm. The SBS was then measured and the data were analyzed using one-way ANOVA, Tukey HSD test and Dunnett's test at 0.05 level of significance. Results: The SBS of the 3 groups was significantly different (P<0.001). The Tukey HSD test revealed that the Er:YAG laser had higher SBS than the CO2 laser group (P<0.001). The Dunnett's test showed that both Er:YAG and CO2 laser groups yielded higher SBS than the control group (P<0.001). Conclusion: The Er:YAG and CO2 laser treatments can increase the SBS of PEEK to composite resin veneers, although the Er:YAG laser seems to be more effective for this purpose.

Application of a Novel Ultra-High Resolution Multi-Detector CT in Quantitative Imaging of Trabecular Microstructure.

To evaluate the performance of a novel ultra-high resolution multi-detector CT scanner (Canon Aquilion Precision UHR CT), capable of visualizing ~150 μm details, in quantitative assessment of bone microarchitecture. Compared to conventional CT, the spatial resolution of UHR CT begins to approach the size of the trabeculae. This might enable measurements of microstructural correlates of osteoporosis, osteoarthritis, and other bone disease. The UHR CT system features a 160-row x-ray detector with 250×250 μm pixels (measured at isocenter) and a custom-designed x-ray source with a 0.4×0.5 mm focal spot. Visualization of high contrast details down to ~150 μm has been achieved on this device, which is now commercially available for clinical use. To evaluate the performance of UHR CT in quantification of bone microstructure, we imaged a variety of human bone samples (including ulna, radius, and vertebrae) embedded in a ~16 cm diameter plastic cylinder and in an anthropomorphic thorax phantom (QRM-Thorax, QRM Gmbh). Helical UHR CT acquisitions (120 kVp tube voltage) were acquired at scan exposures of 375 mAs - 5 mAs. For comparison, the samples were also imaged using a Normal Resolution (NR) mode available on the scanner, involving 500 μm slice thickness, exposure of 50 mAs, and a focal spot of 0.6×1.3 mm. We obtained micro-CT (μCT) of the bone samples at ~28 μm voxel size as a gold-standard reference. Geometric measurements of bone microstructure were performed in 17 regions-of-interests (ROIs) distributed throughout the bones of the phantoms; image registration was used to place the ROIs at corresponding locations in the UHR CT and NR CT. Trabecular thickness Tb.Th, spacing Tb.Sp, and Bone Volume fraction BvTv were obtained. The UHR and NR imaging protocols were compared terms of correlations to μCT and error of trabecular measurements. The effect of dose on trabecular morphometry was also studied for the UHR CT. Furthermore, we evaluated the sensitivity of texture features of trabecular bone (recently proposed as an alternative to geometric indices of microstructure) to imaging protocol. Image texture evaluation was performed using ~150 regions of interest (ROIs) across all bone samples. Three-dimensional Gray Level Co-occurrence Matrix (GLCM) and Gray Level Run Length Matrix (GLRM) features were extracted for each ROI. We analyzed correlation and concordance correlation coefficient (CCC) of the mean ROI values of texture features obtained using the UHR and NR modes. UHR CT reconstructions of bone samples clearly demonstrated improved visualization of the trabeculae compared to NR CT. UHR CT achieved substantially better correlations for all three metrics of bone microstructure, in particular for BvTv (correlation coefficient of 0.91 for UHR CT compared to 0.84 for NR CT) and TbSp (correlation of 0.74 for UHR CT and 0.047 for NR CT). The error obtained with UHR CT was generally smaller than that of NR CT. For TbSp, the mean deviation from μCT (averaged across all bone samples) was only ~0.07 for UHR CT, compared to 0.25 for NR CT. Analysis of reproducibility of texture features of trabecular bone between UHR CT and NR CT revealed fair correlations (>0.7) for the majority of GLCM features, but relatively poor CCC (e.g. 0.02 for Energy and 0.04 for Entropy). The magnitude of texture metrics is particularly affected by the enhanced spatial resolution of UHR CT. The recently introduced UHR CT achieves improved correlation and reduced error in measurements of trabecular bone microstructure compared to conventional resolution CT. Future development of diagnostic strategies based on textural biomarkers derived from UHR CT will need to account for potential sensitivity of texture features to image resolution.

Open channel flow within and above a layered vegetation: Experiments and first-order closure modeling

Flow within vegetation characterized by non-uniform roughness density is drawing significant research attention given its relevance to a plethora of applications in eco-hydraulics including river restoration, and flow in wetland and marshes. The focus here is on flume experiments and modeling of the mean longitudinal velocity profile in a two layered cylindrical vegetation system. Layer 1 represents the region close to the channel bottom where the flow experiences maximum drag due to the densely placed vegetation, while layer 2 represents the flow region above the short vegetation characterized by a smaller vegetation density. Considering the aforementioned arrangements, a new analytical model based on Reynolds-averaged closure principles is proposed to describe the vertical distribution of mean streamwise velocity in an open channel with two different vegetation densities. In the proposed model, the one-dimensional steady and planar-homogeneous momentum equation is used where the turbulent eddy viscosity is assumed to be linearly related to the local mean velocity. The proposed analytical model has been calibrated using experiments reported here in which vegetation is represented by using circular plastic cylinders of two different heights. The proposed model is further tested against published experiments with similar arrangements. In total, 22 different experimental conditions with distinct densities, rigidity, and flow depths have been analyzed. The Root Mean Square Error (RMSE) of the velocity comparisons is found to be less than 0.0342 m/s, which is acceptable.

Small-scale fusion tackles energy, space applications

Efforts are underway to exploit a strategy that could generate fusion with relative ease. On July 14, 2015, nine years and five billion kilometers after liftoff, NASA’s New Horizons spacecraft passed the dwarf planet Pluto and its outsized moon Charon at almost 14 kilometers per second—roughly 20 times faster than a rifle bullet. Samuel Cohen and his team hope to beat the standard timetable for fusion by about a decade using a reactor—initially for rocket propulsion—that’s a fraction of the size and cost of the huge tokamak devices. Cohen’s design takes advantage of the phenomenon of field reversed configuration (FRC), in which a dense mass of ionized plasma holds itself together. Image credit: Princeton Plasma Physics Laboratory. The images and data that New Horizons painstakingly radioed back to Earth in the weeks that followed revealed a pair of worlds that were far more varied and geologically active than anyone had thought possible. The revelations were breathtaking—and yet tinged with melancholy, because New Horizons was almost certain to be both the first and the last spacecraft to visit this fascinating world in our lifetimes. Unless, that is, Samuel Cohen succeeds with the offbeat fusion reactor that he’s developing at the Princeton Plasma Physics Laboratory in New Jersey. Cohen’s current prototype is a clear plastic cylinder that sits in the middle of his lab amidst a dense mass of cables, magnets, and power supplies, emitting a violet pulse of light every two seconds like a two-meter-long strobe light. “We’re only using hydrogen right now,” Cohen explains, referring to the ionized plasma inside the tube that’s emitting the flashes. So there are no actual fusion reactions taking place; that’s not in his research plan until the mid-2020s, when he hopes to be working with a more advanced prototype at least three times larger …

Numerical simulation of elastoplastic problems by Brezis–Ekeland–Nayroles non-incremental variational principle

This paper is concerned with the energy-dissipation Brezis–Ekeland–Nayroles variational principle (BEN principle) for the numerical study of quasi-static elastoplastic and viscoplastic problems in small strains. This principle is based on the dissipation potential and its Fenchel transform and allows to have a consistent view of the whole evolution by computing the nonlinear response along the whole time history as a solution of a suitable minimization problem. In the present work, the BEN principle is applied to address the elastic perfectly plastic and viscoplastic thick hollow cylinder subjected to internal pressure. It turns out that the BEN variational formulation is based on a two-field functional, that leads naturally to discretize the displacement and stress fields. We present the detailing of the discretization and the numerical implementation of the minimization problem by using the mixed finite element method which is more efficient to enforce the yield condition. Computational accuracy and efficiency of the BEN principle is assessed by comparing the numerical results with the analytical ones and the simulations derived by the classical step-by-step finite element procedure.

A heavy intruder in a locally-shaken granular solid.

We experimentally investigate the gravitational-driven motion of a heavy object inside a vertical 2D assembly of identical, plastic cylinders arranged in a regular, triangular lattice. The bottom of the assembly is in contact with a rough plate whose horizontal, sinusoidal motion induces the formation of shear bands in the granular solid, aligned with the edges of the lattice. The intruder sinks when the width of the shear band is as large as its size and halts once the regular configuration of the grains is recovered. The resulting vertical motion of the intruder is random and intermittent, as in disordered granular or colloidal systems near jamming, with alternate flows and blockades. We show, in analogy with earthquakes, that the relation between the size and the duration of the flowing events follows a power-law with an exponent larger than one, and that the statistics of their size is compatible with the Gutenberg-Richter law. We also show that the probability density function of times between flowing events is similar to the Omori law governing the distribution of aftershock sequences following large earthquakes. Finally, the analysis of the velocity fluctuations of the intruder points to a transition from a strong to a weak contact network in the ordered granular assembly, similar to the transition from jammed to fragile states in disordered systems.

ECOLOGICAL AND ECONOMIC ESTIMATION OF THE ARTIFICIAL CLIMATE OBJECTS FOR WINTER GRAINS FROST HARDNESS

To have the selective practice under the conditions of different climatic changes and economic crisis it has appeared possible to use the estimation methods which correspond in particular to the before winter conditions. The selection of winter grains with the highest frost and winter hardness should be estimated under these conditions. Based on the long-term work on studying the problem of winter grains frost and winter hardness especially during the last 10 years it has been stated that the results determination of selection material frost hardness in the seeding boxes which are harden in natural conditions is doubtful due to daytime and nighttime temperature changes as well as to thaw and frost, that is why the given method of plant estimation on its frost hardness should be considered as supplementary.Sudden climatic changes contributes to it. Plant hardening under the nature extreme conditions ( soil bathes ones ) hard are more essential as compared to the fields ones. We managed to connect this year agrometeorological factors as well as to estimate and select frost-winter hardness plants as compared to the increased spike yielding. The study aimed at ecologic progeny testing under the natural provocative conditions (soil bathes) based on the studying of 111 strains of frost-winter hardness plants have been carried on. The purpose of the research was to get the plant off-springs which survived in the winter. To make winter wheat wintering more complicated we used special plastic cylinders which were placed on the soil bathes. The temperature changes are essential in such cylinders as in daytime the soil warming is better as compared to the one in the nighttime. The organic combination of the artificial climate conditions, the extreme nature temperature backgrounds with the fields ones,contribute to the ecological and economic efficient estimation as well as to plant selection, the off-springs of which can be the final selective material in new frost and winter hardness sort selecting. It makes it possible for the selectionist to estimate a great number of selective material due to its frost hardness level in the selection process primary portions as well as to differentiate the sorts according their characteristics. Also, it allows to fulfil the plant selection process with its further off-springs effectiveness.

Experimental Setup for Splash Erosion Monitoring—Study of Silty Loam Splash Characteristics

An experimental laboratory setup was developed and evaluated in order to investigate detachment of soil particles by raindrop splash impact. The soil under investigation was a silty loam Cambisol, which is typical for agricultural fields in Central Europe. The setup consisted of a rainfall simulator and soil samples packed into splash cups (a plastic cylinder with a surface area of 78.5 cm2) positioned in the center of sediment collectors with an outer diameter of 45 cm. A laboratory rainfall simulator was used to simulate rainfall with a prescribed intensity and kinetic energy. Photographs of the soil’s surface before and after the experiments were taken to create digital models of relief and to calculate changes in surface roughness and the rate of soil compaction. The corresponding amount of splashed soil ranged between 10 and 1500 g m−2 h−1. We observed a linear relationship between the rainfall kinetic energy and the amount of the detached soil particles. The threshold kinetic energy necessary to initiate the detachment process was 354 J m−2 h−1. No significant relationship between rainfall kinetic energy and splashed sediment particle-size distribution was observed. The splash erosion process exhibited high variability within each repetition, suggesting a sensitivity of the process to the actual soil surface microtopography.

Dynamic population of N2-fixing cyanobacteria in an organic rice field

Abstract. Hendrayanti D, Rusmana I, Santosa DA, Hamim. 2019. Dynamic population of N2-fixing Cyanobacteria in an organic rice field. Biodiversitas 20: 2883-2890. The existence of free living N2-fixing cyanobacteria in rice fields has been acknowledged as an advantage for rice crops. At present, implementation of organic rice-systems has been increasing as an alternative way for keeping rice fields healthy. Therefore, investigation of N2-fixing cyanobacteria as a part of the soil components is important. Dynamic populations of the filamentous N2-fixing cyanobacteria assemblage in organic rice field at Ciparay, South Bandung, was investigated during the crop’s growth cycle (January-March 2018). Soil samples were collected from four plots of 20 ha rice fields. At each plot, soil from three random stations with three replications was taken using a 3-cm-diameter plastic cylinder. Composite samples from each station were analyzed for colony enumeration (TPC method), relative abundance and frequency, and species identification. The results show that population reached peak on the 80 days after planting (194 x 106 cfu/g soil). Species number decreased following increased density of the rice canopy. Among the 23 morphospecies found along the rice growth, four species were always found during all stages of growth: Halotia wernerae CSO2, Roholtiella mojavensis CSO6, Hapalosiphon welwitschii CSO7, and Desmonostoc danxiaense CSO3. The community of N2-fixing cyanobacteria found in the organic rice field was different to those reported from non-organic rice field.

A soil non-aqueous phase liquid (NAPL) flushing laboratory experiment based on measuring the dielectric properties of soil–organic mixtures via time domain reflectometry (TDR)

Abstract. The term non-aqueous phase liquid (NAPL) refers to a group of organic compounds with scarce solubility in water. They are the products of various human activities and may be accidentally introduced into the soil system. Given their toxicity level and high mobility, NAPLs constitute a serious geo-environmental problem. Contaminant distribution in the soil and groundwater contains fundamental information for the remediation of polluted soil sites. The present research explored the possible employment of time domain reflectometry (TDR) to estimate pollutant removal in a silt-loam soil that was primarily contaminated with a corn oil as a light NAPL and then flushed with different washing solutions. Known mixtures of soil and NAPL were prepared in the laboratory to achieve soil specimens with varying pollution levels. The prepared soil samples were repacked into plastic cylinders and then placed in testing cells. Washing solutions were then injected upward into the contaminated sample, and both the quantity of remediated NAPL and the bulk dielectric permittivity of the soil sample were determined. The above data were also used to calibrate and validate a dielectric model (the α mixing model) which permits the volumetric NAPL content (θNAPL; m3 m−3) within the contaminated sample to be determined and quantified during the different decontamination stages. Our results demonstrate that during a decontamination process, the TDR device is NAPL-sensitive: the dielectric permittivity of the medium increases as the NAPL volume decreases. Moreover, decontamination progression can be monitored using a simple (one-parameter) mixing model.

Bone augmentation using small molecules with biodegradable calcium sulfate particles in a vertical onlay graft model in the rabbit calvarium.

Small molecules including sodium butyrate (SB) and dimethyloxalylglycine (DMOG) can promote bone regeneration via inhibitive effects eliciting cellular responses through signaling cascades. The purpose of this study was to determine the synergistic effects of SB and DMOG loaded on calcium sulfate (CaS) on bone regeneration in the challenging vertical augmentation model in the rabbit calvarium. Four plastic cylinders screwed on the calvarium of each of 10 rabbits were randomly grafted with CaS, CaS/SB, CaS/DMOG, or CaS/DMOG/SB. All specimens were assessed by radiographic, histologic, and histomorphometric analyses. In the radiographic analysis, three different layers (new bone, degraded CaS, and pristine CaS layers) could be distinguished within the cylinder in all groups at 2 weeks. Newly formed bone grew up from basal bone, and CaS in contact with newly formed bone was degraded into small particles to form a different layer. At 8 weeks, most of the pristine CaS had been absorbed and hardly seen within the cylinder. In the histomorphometric analysis, all groups showed comparable new bone areas and heights at 2 and 8 weeks. The DMOG group showed a significant increase in new bone area at 8 weeks compared with 2 weeks, but there was no significant difference among the groups at 8 weeks. The DMOG group showed significantly lower values for the residual material area than the control group at 2 weeks. Within the limitations of this study, SB and DMOG seem to exert smaller synergistic effects on bone regeneration compared to CaS alone in vertical bone augmentation.

Quantitative characterization of ex vivo breast tissue via x-ray phase-contrast tomography.

Grating-based X-ray phase-contrast imaging (GPCI) has received growing interests in recent years due to its high capability of visualizing soft tissue. Breast imaging is one of the most promising candidates for the first clinical application of this imaging modality. In this work, quantitative breast tissue characterization based on GPCI computed tomography (CT) is investigated with a laboratory X-ray tube through a comparison between attenuation-based CT images and phase-contrast CT images. The Hounsfield units (HU) scale was introduced to phase-contrast images due to its wide application in clinical medicine. In this work, instead of water, plastic cylinders composed of polyethylene terephthalate (PET) was treated as the calibration material. An alternative test-retest reliability (TRR) was presented to evaluate the repeatability of GPCI. Comparison between attenuation-based CT imaging and GPCI CT imaging was operated with the use of statistical analysis methods like histograms and receiver operating characteristic (ROC) curves. The determined mean TRR related to cylinders is slightly larger in phase-contrast imaging (0.93) than that in attenuation-based imaging (0.89). With respect to distinguishing breast tissues, the AUC (area under curve) values of ROC curves of phase-contrast images are higher than that of attenuation-based images. An ex vivo study of GPCI shows that it is a stable imaging modality for visualizing the breast tissue with good repeatability, and that it could be of potential for the diagnosis of breast cancer as well.

Terrestrial isopods associated with shallow underground of forested scree slopes in the Western Carpathians (Slovakia).

The shallow underground of forested scree slopes represents a little-studied subterranean biotope. In this paper, species diversity and depth distribution of terrestrial isopod communities studied in the depth profile (5–95 cm from the surface) of eight forested scree slopes in the Western Carpathians (Slovakia) is discussed. The southern edge of the Western Carpathians where the study sites are located represents the northernmost limit of distribution of obligate subterranean fauna in Europe. The sites differ from each other in type of bedrock, forest composition, slope aspect, and altitude. To sample isopods, a set of three subterranean pitfall traps consisting of a plastic cylinder (Ø 110 mm) and ten plastic cups was buried in each studied scree slope. In total, 252 isopods belonging to eleven species were sampled (1–5 species per site). Of the species found, the blind and depigmented Mesoniscusgraniger was the sole species closely associated with deeper parts of the depth profile and was present in most of the sites studied. Another ten species were represented by a small number of individuals and their occurrence deeper in the scree slope profile was rather accidental. A comparison between winter and summer periods indicates apparent differences in seasonal activities of isopods. Ethylene glycol seems to be more appropriate fixative solution for trapping isopods than formaldehyde.

Building an orthopaedic CT phantom for under £50.

In procuring a CT scanner for orthopaedic imaging, the ability of the scanner to cope with metal artefacts for visualising bone and bone lesions around orthopaedic implants is an important feature. A durable and easily transportable CT phantom would help to compare this feature between CT scanners.The aims of this study were to develop a CT phantom that is easy to build, easily transportable, stable over time, cheap and challenging CT scanner performance. A CT phantom resembling a femur and tibia with a total knee replacement was constructed from spare components of a knee replacement, wall filler and polystyrene. A number of plastic strips and cylinders were placed between metal implant and bone substitute during construction to act as "bone lesions". The phantom was fixed in a watertight acrylic box with epoxy resin. The total manufacturing time was below 3 h staggered over several days and the total cost was below £50. When empty, the phantom is easily transportable. The box can be filled with water on site visits ensuring a reproducible attenuation. This phantom is stable (i.e. not affected by decay of biological tissue). The phantom was easy to construct and is well transportable and stable in time. The phantom can be used in a procurement process allowing direct comparison of different scanners regarding technical factors and software performance. It can further be used for quality assurance, scan parameter optimisation and research. We conclude that a simple and transportable CT phantom can be built using few resources that allows to compare CT scanners with respect to their ability to visualise bone lesions around metal implants. It is possible to build a CT knee replacement phantom in a few hours and for less than £50. Other than the total knee implant, this CT phantom can be built with material available from any DIY store and simple tools. This CT phantoms allows objective comparisons in CT procurement. This CT phantom allows objective assessment of imaging protocols for clinical practice.

Expression of Cementitious Pore Solution and the Analysis of Its Chemical Composition and Resistivity Using X-ray Fluorescence.

The goal of this method is to determine the chemical composition and electrical resistivity of cementitious pore solution expressed from a fresh paste sample. The pore solution is expressed from a fresh paste sample using a pressurized nitrogen gas system. The pore solution is then immediately transferred to a syringe to minimize evaporation and carbonation. After that, assembled testing containers are used for the X-ray fluorescence (XRF) measurement. These containers consist of two concentric plastic cylinders and a polypropylene film which seals one of the two open sides. The pore solution is added into the container immediately prior to the XRF measurement. The XRF is calibrated to detect the main ionic species in the pore solution, in particular, sodium (Na+), potassium (K+), calcium (Ca2+), and sulfide (S2-), to calculate sulfate (SO42-) using stoichiometry. The hydroxides (OH-) can be calculated from a charge balance. To calculate the electrical resistivity of the solution, the concentrations of the main ionic species and a model by Snyder et al. are used. The electrical resistivity of the pore solution can be used, along with the electrical resistivity of concrete, to determine the formation factor of concrete. XRF is a potential alternative to current methods to determine the composition of pore solution, which can provide benefits in terms of reduction in time and costs.

Expression of Cementitious Pore Solution and the Analysis of Its Chemical Composition and Resistivity Using X-ray Fluorescence

The goal of this method is to determine the chemical composition and electrical resistivity of cementitious pore solution expressed from a fresh paste sample. The pore solution is expressed from a fresh paste sample using a pressurized nitrogen gas system. The pore solution is then immediately transferred to a syringe to minimize evaporation and carbonation. After that, assembled testing containers are used for the X-ray fluorescence (XRF) measurement. These containers consist of two concentric plastic cylinders and a polypropylene film which seals one of the two open sides. The pore solution is added into the container immediately prior to the XRF measurement. The XRF is calibrated to detect the main ionic species in the pore solution, in particular, sodium (Na+), potassium (K+), calcium (Ca2+), and sulfide (S2-), to calculate sulfate (SO42-) using stoichiometry. The hydroxides (OH-) can be calculated from a charge balance. To calculate the electrical resistivity of the solution, the concentrations of the main ionic species and a model by Snyder et al. are used. The electrical resistivity of the pore solution can be used, along with the electrical resistivity of concrete, to determine the formation factor of concrete. XRF is a potential alternative to current methods to determine the composition of pore solution, which can provide benefits in terms of reduction in time and costs.

Dynamics of collembolan communities inside the forested scree slope

The monthly dynamics of collembolan communities was studied over a year-long period in the depth profile of forested scree slope in the karst area of the Čierna hora Mts. (Western Carpathians, Slovakia). Collembola were sampled using non-baited subterranean traps consisted of a plastic cylinder with the small openings drilled around at 10 horizontal levels (5 – 95 cm), and a system of 10 plastic cups connected to each other by a helical rod and nuts. The plastic cylinder, after being buried in the slope profile, served as a protective casing for inserting the plastic cups filled with the preservative solution. The cups inside the cylinder were placed right under the openings on the cylinder perimeter, enabling to trap specimens in the particular depth. The temperature was measured continuously throughout the study at four-hour intervals using thermo-data loggers affixed to the wall of the plastic cups. During the year, the monthly temperature means on the surface ranged between 0.2°C (January) to 16.6°C (August) while the monthly temperature means at the depth of 95 cm ranged between 3.5°C (April) to 15.2°C (September). Monthly temperature ranges varied from 5.0°C (February) to 12.5 °C (October) on the surface and from 0.5°C (February, April) to 4.5 °C (July) at 95 cm. A total of 60 collembolan species were identified, among them 27 trogloxenes, 19 subtroglophiles, 12 eutroglophiles and 2 troglobionts. Fluctuations of the locomotory activity during the year were observed in all four categories of Collembola and at all depths. Redundancy analysis (RDA) revealed collembolan activity to be substantially affected by the thermal conditions fluctuating over the year. Most eutroglophiles and troglobionts, associated with deeper layers of the scree slope, preferred rather lower temperature ranges and were typical of the autumn months.