sample width effect
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Textile fabrics are highly anisotropic, so that their mechanical properties including strengths are a function of direction. An extreme case is when a woven fabric sample is cut in such a way where the bias angle and hence the tension loading direction is around 45° relative to the principal directions. Then, once loaded, no yarn in the sample is held at both ends, so the yarns have to build up their internal tension entirely via yarn-yarn friction at the interlacing points. The overall fabric strength in such a sample is a result of contributions from the yarns being pulled out and those broken during the process, and thus becomes a function of the bias direction angle θ, sample width W and length L, along with other factors known to affect fabric strength tested in principal directions. Furthermore, in such a bias sample when the major parameters, e.g. the sample width W, change, not only the resultant strengths differ, but also the strength generating mechanisms (or failure types) vary. This is an interesting problem and is analysed in this study. More specifically, the issues examined in this paper include the exact mechanisms and details of how each interlacing point imparts the frictional constraint for a yarn to acquire tension to the level of its strength when both yarn ends were not actively held by the testing grips; the theoretical expression of the critical yarn length for a yarn to be able to break rather than be pulled out, as a function of the related factors; and the general relations between the tensile strength of such a bias sample and its structural properties. At the end, theoretical predictions are compared with our experimental data.
- Klíčová slova
- bias directions, fabric strength, failure types, sample width effect, yarn pullout and breakage,
- Publikační typ
- časopisecké články MeSH
Recent research has reported an association between facial width-to-height ratio (fWHR) and both fighting performance and judgments of formidability in a sample of mixed martial arts (MMA) combatants. The results provide evidence of fWHR being associated with sporting performance and aggression in men. However, it has been argued that the effect of fWHR might be a by-product of associations between body size and behavioral measures. Here we tested whether fWHR is associated with perceived aggressiveness, fighting ability and success in physical confrontation, while controlling for body size, also in a sample of MMA fighters. We found that perceived fighting ability was predicted by weight but not by fWHR. In contrast, both fWHR and body weight independently predicted perceived aggressiveness. Furthermore, we found positive associations between fWHR and fighting performance which appear to be independent of body size. Our findings provide further support for the proposal that fWHR is associated with fighting ability and perceived aggression, and that these effects are independent of body size. Therefore, fWHR might be considered as a viable and reliable marker for inference of success in male intra-sexual competition.
- Klíčová slova
- aggression, fWHR, fight, formidability, perception,
- MeSH
- agrese fyziologie MeSH
- bojové sporty fyziologie MeSH
- lidé MeSH
- obličej anatomie a histologie MeSH
- rozpoznání obličeje fyziologie MeSH
- sociální percepce * MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- komentáře MeSH
- práce podpořená grantem MeSH
The evolution partial differential equations describing the transport processes induced by hydrodynamic flow in free-flow electrophoresis (FFE) are solved by the generalized dispersion theory. Our theoretical analysis demonstrates that the central injection of solutes into a relatively fast hydrodynamic flow enables to transport them to the channel outlet well before they are spread through the width of the channel and their migration is negatively affected by a contact with walls. In this case, the axial zone spreading decreases by increasing the linear velocity of hydrodynamic flow. The resulting dependencies of convective and dispersion coefficients on the velocity of flow and parameters of the separation channel show the optimum separation conditions with respect to resolution and analysis time. Due to the unsteady character of transport processes, effective FFE separations can potentially be performed in a microfluidic device in seconds. This is a reasonable time to separate low-molecular mass impurities in the electric field. Thus, a fast and efficient sample cleaning before subsequent analysis by electrospray ionization-mass spectrometry (ESI-MS) or another separation method can be performed.
Toxic metal contamination of the environment is a global issue. In this paper, we present a low-cost and rapid production of amalgam electrodes used for determination of Cd(II) and Pb(II) in environmental samples (soils and wastewaters) by on-site analysis using difference pulse voltammetry. Changes in the electrochemical signals were recorded with a miniaturized potentiostat (width: 80 mm, depth: 54 mm, height: 23 mm) and a portable computer. The limit of detection (LOD) was calculated for the geometric surface of the working electrode 15 mm² that can be varied as required for analysis. The LODs were 80 ng·mL-1 for Cd(II) and 50 ng·mL-1 for Pb(II), relative standard deviation, RSD ≤ 8% (n = 3). The area of interest (Dolni Rozinka, Czech Republic) was selected because there is a deposit of uranium ore and extreme anthropogenic activity. Environmental samples were taken directly on-site and immediately analysed. Duration of a single analysis was approximately two minutes. The average concentrations of Cd(II) and Pb(II) in this area were below the global average. The obtained values were verified (correlated) by standard electrochemical methods based on hanging drop electrodes and were in good agreement. The advantages of this method are its cost and time effectivity (approximately two minutes per one sample) with direct analysis of turbid samples (soil leach) in a 2 M HNO₃ environment. This type of sample cannot be analyzed using the classical analytical methods without pretreatment.
- Klíčová slova
- amalgam electrodes, electrochemistry, heavy metals, soil, turbid sample,
- Publikační typ
- časopisecké články MeSH
The recent developments in multiaxis three-dimensional (3D) printing have got a large potential for expanding the capability of material extrusion based methods. Especially curved and nonplanar methods can improve buildability, surface quality, and mechanical performance. However, the challenges that arise from using them complicate their deployment. In this article, we propose a hybrid planar method, based on varying the layer height and deposition speed in combination with tool reorientation, that allows us to get a lot of the same benefits that come from using nonplanar layers. The goal of the method is to keep the deposition constant regardless of the overhang angle. This is achieved by simultaneous control of layer height, deposition speed, and tool orientation. The method is the most beneficial for large-scale, single-wall 3D printing, such as clay, concrete, and other composites. The main restriction of the method depends on the minimum/maximum ratio between the nozzle diameter and layer height. A description of the method is provided, and sample objects are evaluated either as trajectories or as test prints. The claims are confirmed by microscopy measurement of the contact patch width. The method as presented allows printing of overhangs up to 82.34°, can be applied to complex geometry without difficulties, and further possibilities of limit expansion are discussed. The contact patch width decreases only by 20% at the 80° of overhang.
- Klíčová slova
- 3D printing method, intralayer height variation, multiaxis, process planning, variable layer height,
- Publikační typ
- časopisecké články MeSH
The present paper examines the effect of gamma radiation on the proteolytic effectiveness of pepsin of an activity of 6640, 8940 and 11,333 units in 1 g, expressed according to the Czechoslovak Pharmacopoeia. The samples were irradiated with graded doses from 5.2 to 128.7 kGy so that the course of inactivation could be determined. Effectiveness was determined six times in each sample and parallel experiments were statistically evaluated. The results are shown in Tables 1 to 3. The relative width of the interval of reliability only exceptionally exceeds 5%. A decrease in effectiveness shown in Fig. 1 shows that the course of the decrease in effectiveness did not depend in the interval used on the initial activity of the enzyme. In the semilogarithmic arrangement in Fig. 2, the dependence of the decrease in effectiveness on the dose possesses a linear course. The decrease in effectiveness in dependence on the dose of radiation can be approximately read in the graph in Fig. 3. The Czechoslovak Pharmacopoeia prescribes a dose of 24 kGy to achieve sterility by means of ionizing radiation. When microbiological indefectibility is the case, a smaller dose suffices, depending on the level of the initial contamination and the resistance of the present microorganisms. It usually does not exceed 10 kGy, in our case even 5 kGy. Nevertheless, there occurs a loss of effectivity, in the extreme case 10-13%. The largest dose used in the present paper decreased effectiveness by 60%. If ionizing radiation is to be used to decontaminate pepsin, a certain decrease in activity must be taken into account. In addition, a toxicological evaluation must be recommended.
- MeSH
- pepsin A metabolismus účinky záření MeSH
- prasata MeSH
- techniky in vitro MeSH
- žaludeční sliznice enzymologie MeSH
- záření gama MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- Názvy látek
- pepsin A MeSH
The arbuscular mycorrhizal (AM) fungi are a globally distributed group of soil organisms that play critical roles in ecosystem function. However, the ecological niches of individual AM fungal taxa are poorly understood. We collected > 300 soil samples from natural ecosystems worldwide and modelled the realised niches of AM fungal virtual taxa (VT; approximately species-level phylogroups). We found that environmental and spatial variables jointly explained VT distribution worldwide, with temperature and pH being the most important abiotic drivers, and spatial effects generally occurring at local to regional scales. While dispersal limitation could explain some variation in VT distribution, VT relative abundance was almost exclusively driven by environmental variables. Several environmental and spatial effects on VT distribution and relative abundance were correlated with phylogeny, indicating that closely related VT exhibit similar niche optima and widths. Major clades within the Glomeraceae exhibited distinct niche optima, Acaulosporaceae generally had niche optima in low pH and low temperature conditions, and Gigasporaceae generally had niche optima in high precipitation conditions. Identification of the realised niche space occupied by individual and phylogenetic groups of soil microbial taxa provides a basis for building detailed hypotheses about how soil communities respond to gradients and manipulation in ecosystems worldwide.
- Klíčová slova
- arbuscular mycorrhizal fungi, ecological niche, molecular taxa, niche optimum, niche width, pH, phylogenetic correlation, temperature,
- MeSH
- ekosystém MeSH
- fylogeneze MeSH
- houby MeSH
- koncentrace vodíkových iontů MeSH
- mykorhiza * MeSH
- půda MeSH
- půdní mikrobiologie MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- půda MeSH
We explored the transition of 13 X-linked markers across two separate portions of the house mouse hybrid zone, asking whether such a comparison can distinguish the effects of selection from random factors. A heuristic search in the likelihood landscape revealed more complex likelihood profiles for data sampled in two-dimensional (2D) space relative to data sampled along a linear transect. Randomized resampling of localities analyzed for individual loci showed that deletion of sites away from the zone center can decrease cline width estimates whereas deletion of sites close to the center can significantly increase the width estimates. Deleting localities for all loci resulted in wider clines if the number of samples from the center was limited. The results suggest that, given the great variation in width estimates resulting from inclusion/exclusion of sampling sites, the geographic sampling design is important in hybrid zone studies and that our inferences should take into account measures of uncertainty such as support intervals. The comparison of the two transects indicates cline widths are narrower for loci in the central part of the X chromosome, suggesting selection is stronger in this region and genetic incompatibilities may have at least partly common architecture in the house mouse hybrid zone.
- MeSH
- druhová specificita MeSH
- genetické markery genetika MeSH
- genotyp MeSH
- hybridizace genetická * MeSH
- myši genetika MeSH
- pravděpodobnostní funkce MeSH
- rozmnožování genetika MeSH
- selekce (genetika) * MeSH
- stochastické procesy MeSH
- vznik druhů (genetika) * MeSH
- zeměpis MeSH
- zvířata MeSH
- Check Tag
- myši genetika MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Geografické názvy
- Česká republika MeSH
- Německo MeSH
- Názvy látek
- genetické markery MeSH
Non-targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a widely used tool for metabolomics analysis, enabling the detection and annotation of small molecules in complex environmental samples. Data-dependent acquisition (DDA) of product ion spectra is thereby currently one of the most frequently applied data acquisition strategies. The optimization of DDA parameters is central to ensuring high spectral quality, coverage, and number of compound annotations. Here, we evaluated the influence of 10 central DDA settings of the Q Exactive mass spectrometer on natural organic matter samples from ocean, river, and soil environments. After data analysis with classical and feature-based molecular networking using MZmine and GNPS, we compared the total number of network nodes, multivariate clustering, and spectrum quality-related metrics such as annotation and singleton rates, MS/MS placement, and coverage. Our results show that automatic gain control, microscans, mass resolving power, and dynamic exclusion are the most critical parameters, whereas collision energy, TopN, and isolation width had moderate and apex trigger, monoisotopic selection, and isotopic exclusion minor effects. The insights into the data acquisition ergonomics of the Q Exactive platform presented here can guide new users and provide them with initial method parameters, some of which may also be transferable to other sample types and MS platforms.
Chloride (Cl-) is an inorganic anion present in a broad range of samples (e.g. biological, environmental, food, water, etc.), the determination of which is of widespread significance. In this work, we translate the well-established traditional argentometric method (Mohr's precipitation titration) into a small, simple, portable, and low-cost paper-based microfluidic diagnostic device, which provides rapid and quantitative analysis. The developed device enables the determination of chloride sample volumes as small as 5 μL. A distance-based detection method is implemented providing fully instrument-free quantitation. The beneficial effects of channel geometry (variable widths with constant heights) on analytical parameters were investigated. Trapezoidal channels (channel width changes linearly with height) were used to create a gradient of paper surface (titrant) available for the reaction, compared to the typical uniform rectangular channels (constant channel width). The trapezoid with increasing width offered higher sensitivity and lower detection limits (i.e. 0.05 mM vs 0.1 mM from the rectangular channel) for chloride determination across the concentration range of 0.05-25 mM. In addition, the effect of concentration of the deposited reagent on the obtained distance signals was investigated using varying concentrations of titrant (AgNO3), which allowed determination of chloride across a wider dynamic range (up to 200 mM). The utility of the paper devices was demonstrated by determination of chloride in a variety of matrices including body fluids (sweat, serum, and urine) and water samples (drinking, mineral, river water).
- Klíčová slova
- Argentometric determination, Asymmetric trapezoidal microfluidic channels, Chloride determination, Distance-based measurement, Microfluidic paper-based analytical device,
- MeSH
- chloridy analýza MeSH
- lidé MeSH
- mikrofluidní analytické techniky * MeSH
- papír * MeSH
- povrchové vlastnosti MeSH
- tělesné tekutiny chemie MeSH
- voda chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chloridy MeSH
- voda MeSH
