Relative Density Research Articles

Large-torque and fast-response electrothermal-motivated liquid crystal elastomer twisted yarn actuators

Analogous to biological muscles, twisted yarns with the capacity to output torsional torque and reversible rotation are of significant value in the development of soft robotic systems. However, how to achieve large torque while efficiently integrating electrical control elements to the soft actuators remains scientific and engineering challenges. Here, by concentric twisting a flexible silver-plated polyamide strand (SPS) with multi-layer liquid crystal elastomer fibers (LCEFs), a twisted yarn actuator with the skin-core structure that exhibits outstanding rotational motion under the electrical current control is fabricated. It has been proved that this multi-layered twisting structure efficiently improves the actuating performance. The yarn actuator can produce a peak torque of 33.4 N m kg−1 which outperforms reported commercial rotating motors and a specific power density of 21.2 W kg−1 that is comparable to the human skeletal muscle. As conceptual applications, electrical soft rotors and a novel flexible lifter have been successfully constructed based on the twisted yarn actuator, demonstrating precise torque responsiveness and controllability. Furthermore, a smart crawling fabric embedded with the twisted yarn actuators has been weaving fabricated which can crawl forward continuously and achieve the crawling stroke of 19.9 mm in 55 s and a maximum speed of 1.1 mm s−1. The research provides insights for designing soft robots employing fabric structures.

Tasar Silkworm Pupae oil: A potential therapeutic and edible lipid source to mitigate the oxidative stress and cholesterol complications associated with diabetes

The anti-oxidant and cholesterol-lowering activity of tasar pupae oil (TPO), loaded with α-linolenic acid in streptozotocin-induced diabetic Wistar rats was studied. The suitability of TPO as an edible oil was investigated through characterizations including refractive index, specific gravity, rheological profile, and NMR spectroscopy. The in vitro radical-scavenging activity of TPO was tested using ABTS assay. The diabetic rats were orally supplemented with two different doses of TPO (high or low) for seven days. The physical parameters, including a refractive index, a specific gravity, and a rheological profile are indicated as favorable attributes of TPO as edible oil. The NMR analysis suggested that TPO contains stearic acid and linolenyl chain compounds. TPO exhibited robust in vitro radical-scavenging activity, with an IC50 of 1.33 µl/ml. In vivo study showed that the total serum lipid content was significantly lower in the TPO treated groups compared to other groups. However, blood glucose level did not reduced in TPO treated groups. The levels of anti-oxidant enzymes CAT and SOD were enhanced by both doses of TPO in diabetic rats indicating the significant anti-oxidant activity of TPO. In addition, Histopathological evaluations indicated no signs of toxicity in hepatic and renal tissues of TPO-treated diabetic rats. Hence, taking into consideration these activities, the tasar pupae oil can be further investigated for its therapeutic and edible properties.

Study on Characteristics of Soil Profile Stability Indexes in Sakita

This research examines the suitability of soil as infrastructure which can help in the classification and identification of its properties for ideal engineering structures. Sakita, an area in Gesse III as a case study, is a virgin land, allocated for residential buildings. The need to investigate the soil profile in the report area prompted these studies as its physical properties are used for classifying its various engineering applications. These properties indicate qualitative behaviors of soil when subjected to various types of loads. Apart from physical/visual observation made of the soil, trial pits were dug to depths of 0.5m, 1.0m, 1.5m, 2.0m, and 2.5m respectively and disturbed soil samples were taken for tests. The disturbed soil samples obtained were analyzed for grading including mechanical sieve analysis, specific gravity, plastic limit, liquid limit, and bulk density tests. The resistances of the cone against penetration, compaction, consolidation, and permeability properties were also assessed. The detected geotechnical properties varied significantly with depth, except for specific gravity, which did not vary significantly at 0.5 m with depth. Soil samples from all pits consist mainly of poorly sorted gravel and sand with little fineness. They contain a medium- to coarse-grained fraction of sand on average above 85%. The puncture resistance obtained from the cone puncture test ranges from 100 knm2 to 950 knm2. The average safe bearing capacity estimated for the footing using a factor of safety of 3 at a depth of 1 m was not less than 473 km2 anywhere in the study area. The samples from the three locations generally have good compaction parameters, medium to high permeability, and low compressibility. The highest load-bearing capacity is associated with the lateralized basement ceiling. This means that the safety depth for placing infrastructure foundations in the prescribed research area (Sakita) is the depth where it meets the lateralized basement.

Laser energy-dependent processability of non-equiatomic TiNbMoTaW high-entropy alloy through in-situ alloying of elemental feedstock powders by laser powder bed fusion

Pre-alloyed powder, which is primarily used in laser powder bed fusion (LPBF), has the disadvantages of requiring time and high manufacturing costs. To overcome these limitations, in-situ alloying, which mixes pure elemental powders and alloys them in real-time during the LPBF process, has attracted attention. In particular, manufacturing high entropy alloys (HEA) containing high-melting-point refractory elements through in-situ alloying presents considerable challenges. In this study, a non-equiatomic single body-centered cubic (BCC) solid-solution HEA was fabricated via in-situ alloying with Ti, Nb, Mo, Ta, and W powders through the LPBF process. Specifically, by applying a high volumetric energy density (VED), we successfully mitigated the segregation of constituent elements, leading to an enhanced crystallographic texture. Consequently, the reduction in the residual stress and high-angle grain boundary (HAGB) density progressed, contributing to an increased relative density. Thus, this study marks a pioneering endeavor for in-situ alloyed HEA fabrication via LPBF, illustrating the efficacy of in-situ alloying utilizing mixed powders.

Mechanisms affecting microwave dielectric properties of Li2Mg2TiO5 ceramics based on lithium excess

Herein, the feasibility was assessed through first principles, and the effect of lithium excess on both the structure and dielectric properties of Li(1+x)2Mg2TiO5 (0.000 ≤ x ≤ 0.200) ceramics was investigated by solid-phase reaction method. An appropriate excess of lithium can moderately inhibit the volatilization of lithium and reduce the production of the secondary phase MgTi2O4, though it cannot completely inhibit its production. Li(1+0.050)2Mg2TiO5 exhibits the best dielectric properties with εr =14.55, Q × f =127,393 GHz (@9.6 GHz), and τf = −19.91 ppm/°C. The influence of non-inherent factors on the dielectric properties is dominant, with the increase in relative density to 93.53 % and the growth in average grain size to 28.67 μm contributing to the reduction of dielectric loss. The decrease in εr is due to the decrease in secondary phase content. Results from bond ionicity and Raman wavenumber variations in the intrinsic factors show that the intrinsic factors have little effect on the εr. Whereas, the increase in lattice energy as well as the decrease in FWHM contribute to the decrease in dielectric loss. In addition, a proper excess of lithium helps to increase the bonding energy thereby optimizing the temperature stability. The optimized Li(1+0.050)2Mg2TiO5 has great potential for application in microwave communications.

Evaluation on the diffusion-fusion properties and interfacial mechanical behavior of virgin and aged asphalt

To investigate the regeneration mechanisms of rejuvenated asphalt mixtures, molecular simulation techniques were employed to research virgin and aged asphalt's fusion characteristics and interface mechanical properties. The blended zone was identified based on relative density distribution, and a molecular-scale calculation method for the Degree of binder Blended (DOB) between virgin and aged asphalt was proposed. Finally, the influence of DOB on the mechanical properties of the asphalt-aggregate interface was evaluated through interface pull-out tests. The results revealed that the proposed molecular-scale DOB calculation method effectively assessed the blending effectiveness between virgin and aged asphalt. Higher degrees of asphalt aging made it more challenging for aged asphalt to fuse with virgin asphalt, while elevated temperatures facilitated diffusion fusion between them. Under tensile loading, initial cracks were primarily initiated from the rejuvenated asphalt's blended zone. This region represented the weakest area within the interface system and was prone to fracture under load. The increase in DOB significantly improved the interfacial properties of recycled asphalt, with the increase in DOB the interfacial tensile strength increased by 4%–14% and the fracture energy increased by 10%–19%. However, this enhancement effect diminished with an increased degree of asphalt aging. At the molecular scale, increasing DOB improved the interface strength and deformation resistance of rejuvenated asphalt. The molecular simulation results provide theoretical guidance for evaluating the fusion degree of aged asphalt in RAP materials and determining the utilization efficiency of aged asphalt.

Variation in specific gravity and shrinkage of tapped rubberwood

Hevea brasiliensis (rubber tree), a major source of natural rubber, could also be an important source of lumber as senescence occurs. However, latex collection is known to affect Hevea brasiliensis (rubber tree) wood formation and consequently, wood properties. The impact tapping (cutting made in the bark of the tree for latex harvest) has on the tree and the way the tree responds after tapping is often overlooked. Knowledge on wood properties of tapped rubber trees in Nigeria would enhance its sustainable utilization which is especially important in developing countries where lumber is limited. Variation in specific gravity and shrinkage of rubberwood wood due to tapping duration was examined. Tapping duration had significant effect in specific gravity and longitudinal shrinkage of rubberwood but had no effect on tangential and radial shrinkage. The specific gravity (SG) of rubberwood ranged from 0,55 - 0,59. Longitudinal shrinkage (average 1,42 %) was higher than typically observed for mature wood. Average tangential shrinkage for rubberwood of all the ages was 5,37 % while radial shrinkage ranged from 2,87 % to 3,84 %. decrease in SG observed in trees tapped for 20 years may indicate the initiation of senescence. Tapped rubberwood could be used in areas not exposed to high moisture as well as in other wood composites.

The effect of relative density, granularity and size of geogrid apertures on the shear strength of the soil/geogrid interface

The increasing use of geogrid in various geotechnical projects has made the evaluation of the shear behavior of soil reinforced with geogrid become particularly important. In this article, a series of large-scale direct shear tests have been performed on sand and gravel samples reinforced with geogrid. The purpose of the experiments was to investigate the impact of the geogrid mesh size and the relative density of the samples on the shear strength coefficient of the interface between soil and geogrid. In this study, 5 geogrids with different mesh sizes and one type of geotextile were used. According to the results, the average shear strength coefficient of sand and gravel samples reinforced with geogrid for different normal stresses and different relative densities was obtained between 0.72 and 0.94. As the relative density increases, the interface shear strength coefficient decreases, this means that the denser the sand, the more the shear strength of the sand/geogrid interface decreases. Based on the results, it was found that the contribution of particle interlocking in the shear resistance of the sand/geogrid interface is particularly important, so that the shear resistance coefficient of the interface increases with the increase in the size of the geogrid mesh.

Polyherbal Formulation Development, Evaluation and Pharmacological Screening for Hepatoprotective Activity.

The current research work investigates the hepatoprotective action of polyherbal formulation prepared from ethanolic extracts of Azadirachta indica A. Juss, Moringa oleifera Lam, Cymbopogon citrates (DC.) Stapf, Tinospora cordifolia (Thumb.) Miers, Ricinus communis L., against experimental hepatotoxicity. The World Health Organization (WHO) is promoting herbal remedies derived from traditional medicinal plants in several countries. The main goal of this investigation was to create and evaluate the polyherbal formulation to protect albino Wistar rats against the hepatotoxic effects of CCl4. Three potential suspensions, polyherbal formulations A, B, and C, were formulated by trituration method using ethanolic extracts of specific medicinal plant components with different sodium carboxy methyl cellulose concentrations 1, 1.5, and 2%, respectively and evaluated the same for both certain physiochemical parameters, including organoleptic characteristics, pH, viscosity, sedimentation volume, redispersibility, density, specific gravity, zeta potential, and accelerated stability studies for three months and for hepatoprotective activity also. Evaluation parameters for Polyherbal Formulation-C have shown good results that met the specifications, with pleasant texture and appearance. Along with other physiochemical qualities, like pH, viscosity, flow rate and sedimentation, were all unchanged and showed significant hepatoprotective effects by reducing elevated serum enzyme levels SGOT, SGPT, ALP, total and direct bilirubin. It was discovered that each quality control parameter in the polyherbal suspension C formulation was thoroughly adequate and improved the recovery from hepatotoxicity caused by CCl4. These findings suggest that the produced polyherbal suspension C (containing ethanolic extracts of A. indica A. Juss, M. oleifera Lam, C. citrates (DC.) Stapf, T. cordifolia (Thumb.) Miers, R. communis L. may be stable, secure, and effective for use and exhibited notable hepatoprotective effects, possibly resulting from the combined impact of all these extracts.

Baru nut oil physicochemical properties, fatty acid and mineral nutritional quality: a high source of oligoelement selenium

Baru nut (Dipteryx alata Vogel) oil obtained by cold pressed machine yielded 24% (mg g–1), primarily composed of unsaturated fatty acids (⁓ 79%), with oleic and linoleic acids in the proportion of 2:1. The oxidative stability assessed by Rancimat method, Thermogravimetry analysis and Differential Scanning Calorimetry revealed thermal stability, which attributed to a higher amount of oleic than linoleic fatty acids, synergistic action of the natural antioxidants and low iodine index. The nutritional qualities were calculated to atherogenic (AI = 0.07), thrombogenic (TI = 0.22) and hypocholesterolemic/ hypercholesterolemic (HH = 13.77), and physicochemical indices: acidity (0.62), peroxide (9.99), saponification (179.93) were higher, whereas iodine (93.00) and relative density (0.9121) were found between the recommended Codex Alimentarius parameters. Mineral elements were quantified using ICP OES (inductively coupled plasma optical emission spectroscopy) in decreased order of Mg > Se > Zn > Mn > Al > Cu, whereas As, Co, Cd, Cr, Fe, Ni, and Pb < LOD. In addition, this oil showed optimal indices to non-cancer risk (CR < 10–6), and non-carcinogenic: hazard quotient (HQ), and total hazard indices (HI) < 1. Nevertheless, major attention is necessary for children and Se hypersensitive consumers, which baru oil daily consumption quantity was estimated based on selenium (Se) trace element at 0.7964 g kg–1. Thus, we recommend the consumption of baru nut oil for human health promotion and metabolic disease prevention.

Phase-Field Simulation and Dendrite Evolution Analysis of Solidification Process for Cu-W Alloy Contact Materials under Arc Ablation

Cu-W alloys are widely used in high-voltage circuit breaker contacts due to their high resistance to arc ablation, but few studies have analyzed the microstructure of Cu-W alloys under arc ablation. This study applied a phase-field model based on the phase-field model developed by Karma and co-workers to the evolution of dendrite growth in the solidification process of Cu-W alloy under arc ablation. The process of columnar dendrite evolution during solidification was simulated, and the effect of the supercooling degree and anisotropic strength on the morphology of the dendrites during solidification was analyzed. The results show that the solid–liquid interface becomes unstable with the release of latent heat, and competitive growth between dendrites occurs with a large amount of solute discharge. In addition, when the supercooling degree is 289 K, the interface is located at a lower height of only 15 μm, and the growth rate is slow. At high anisotropy, the side branches of the dendrites are more fully developed and tertiary dendritic arms appear, leading to a decrease in the alloy’s relative density and poorer ablation resistance. In contrast, the main dendrites are more developed under high supercooling, which improves the density and ablation resistance of the material. The results in this paper may provide a novel way to study the microstructure evolution and material property changes in Cu-W alloys under the high temperature of the arc for high-voltage circuit breaker contacts.

Investigation of SDS on Corrosion Behavior and Discharge Performance of AZ31B Magnesium Alloys in Aqueous Magnesium Air Batteries

Abstract To address the issue of high self-corrosion rate of Mg anodes in seawater batteries leading to low discharge efficiency, the green inhibitor, sodium dodecyl sulfate (SDS), was utilized to enhance the discharging performance of AZ31B alloy. The addition of SDS in a 3.5% NaCl solution led to a reduction in the corrosion rate of AZ31B alloy due to the formation of S-containing compounds. During the continuous-discharging period, the addition of 0.05M SDS increased the anodic utilization efficiency from 64% to 81% and the specific energy density of the entire battery elevated from 1280 to 1912 mAh g-1 (an increase of 49%). The enhancement of the discharge performance of AZ31B Mg alloy in a 3.5% NaCl solution by SDS can be attributed to three aspects: reducing the negative difference effect of the Mg alloy, decreasing the accumulation of corrosion products on the surface of the Mg alloy, and promoting a more uniform dissolution of the Mg alloy.

Statistical modeling and optimization of process parameters for additive manufacturing of styrene–ethylene–butylene–styrene block copolymer parts using solvent cast 3D printing technique

AbstractAdditive manufacturing of thermoplastic elastomers is challenging using fused deposition modeling due to their high melt viscosity, low column strength, and poor fusion among layers. Solvent‐cast 3D printing (SC‐3DP) is an efficient alternative to successfully 3D print such materials. However, selection of suitable 3D printing parameters is crucial to realize parts with optimum physicomechanical properties. In this work, statistical modeling and SC‐3DP parameter optimization for styrene–ethylene–butylene–styrene (SEBS) block copolymer were performed. The effect of 3D printing process parameters on shrinkage, relative density, and tensile strength was analyzed using response surface methodology. Experiments were planned as per central composite design and analysis of variance was performed to evaluate the significant parameters. SEBS content in the polymer solution significantly affected the shrinkage of SC‐3DP samples. Moreover, relative density and tensile strength were significantly affected by print speed and layer height. A significant interaction between print speed and layer height was also noticed for tensile strength and relative density of printed samples. Multi‐objective optimization using genetic algorithm was also performed to minimize shrinkage and maximize relative density and tensile strength. Finally, a case study was conducted comparing the physicomechanical properties of SC‐3DP samples printed at optimized process parameters and compression molded samples.Highlights Statistical models were developed using response surface methodology. Genetic algorithm based multi‐objective optimization was performed. Optimum solvent‐cast 3D printing (SC‐3DP) process parameters were determined.

Is the low-energy tail of shock-accelerated protons responsible for over-ionized plasma in supernova remnants?

Abstract Over-ionized, recombining plasma is an emerging class of X-ray bright supernova remnants (SNRs). This unique thermal state, where the ionization temperature ($T_{\rm z}$) is significantly higher than the electron temperature ($T_{\rm e}$), is not expected from the standard evolution model that assumes a point explosion in a uniform interstellar medium, thus requiring a new scenario for the dynamical and thermal evolution. A recently proposed idea attributes the over-ionization state to additional ionization contribution from the low-energy tail of shock-accelerated protons. However, this new scenario has been left untested, especially from the atomic physics point of view. We report calculation results of the proton impact ionization rates of heavy-element ions in ejecta of SNRs. We conservatively estimate the requirement for accelerated protons, and find that their relative number density to thermal electrons needs to be higher than $5\ (k T_{\rm e}/1\:\mbox{keV})\%$ in order to explain the observed over-ionization degree at $T_{\rm z}/T_{\rm e} \ge 2$ for K-shell emission. We conclude that the proton ionization scenario is not feasible because such a high abundance of accelerated protons is prohibited by the injection fraction from thermal to non-thermal energies, which is expected to be $\sim\! 1\%$ at most.

Synergistic interaction behavior of deformation mechanisms in a new metastable β-Ti alloy with high strain hardening rate

The present study successfully designed a novel metastable β titanium alloy, Ti–8.8Cr–1.9Sn, exhibiting exceptionally high strain-hardening rate (∼2.4 GPa) as well as significant total elongation (∼48.2 %). Detailed analysis of the microstructure revealed that the successive activation of primary mechanical twins and primary SIM α" within β phases, along with secondary mechanical twins and secondary SIM α" within twinning zones during deformation, which results in a highly intricate network of deformation microstructures. Meanwhile, during deformation the microstructure undergoes dynamic refinement through the continuous occurrence of mechanical twinning and phase transformations, leading to a reduction in dislocation mean free path, thereby enhancing the strain-hardening rate. Importantly, the microstructural heterogeneity is formed due to generation of numerous heterogeneous interfaces, including β/α'', β/twin, α''/twin as well as twin/twinnano, thereby inducing additional HDI hardening resulting from the formation of GNDs for accommodating strain gradients near these interfaces. Furthermore, the relative mobile dislocation density ρm/ρm0 is significantly high during deformation, due to a reduced exhaustion rate and a high nucleation rate of mobile dislocations. The values of activation volume Va and V∗ typically range from 1b3–100b3, indicating the occurrence of cross-slip and dislocation nucleation. The interaction and accumulation between GNDs and mobile dislocations further contribute to the improvement of strain hardening rate. Therefore, the synergistic interaction activities of multiple deformation mechanisms lead to enhanced strain-hardening rate along with the large plasticity.

Effect of Bispyribac-Sodium and Spacing on The Weed Control and Performance of Aromatic Rice Varieties

Rice (Oryza sativa L.), a staple grain, serves as a fundamental dietary component for billions by providing carbohydrates, vitamins, and minerals, supporting livelihoods, and stimulating national economies. A field experiment was led from July to December 2019 at the Sher-e-Bangla Agricultural University’s agronomy field in Dhaka, Bangladesh, to determine how a post-emergent herbicide and spacing impacts aromatic rice varieties' growth, yield, and weed control. The investigation consisted of three factors, i.e., weed control treatments: weedy check (no weeding) and Bispyribac-sodium WP @ 150 g ha−1, aromatic rice varieties: Kalizira and BRRI dhan37 and spacing: 20 cm × 15 cm, 25 cm × 15 cm, 20 cm × 20 cm, and 25 cm × 25 cm in a split-split plot design with three replications. Thirteen dissimilar types of weeds invaded the experimental plots. Among them, Monochoria vaginalis was the most prevalent weed at 30 and 60 DAT (24.67 and 19.67 weed population m−2 and 15.24 and 13.02% relative weed density sequentially). Among all the factors, the application of Bispyribacsodium WP (W1), BRRI dhan47 (V2, grain yield 2.99 t ha−1) and 20 cm × 20 cm (S3, grain yield 2.87 t ha−1) spacing provided promising results. According to the findings, BRRI dhan37 planted at 20 cm × 20 cm spacing, along with the suggested application of Bispyribac-sodium WP could provide the best result. Bangladesh Agron. J. 2024, 26(2): 56-66

Progressive development of soil arching and deformations in two and three-dimensional trapdoor tests

This study conducted Two- and three-dimensional (3D) trapdoor tests using a newly developed trapdoor test device, to investigate the evolution of soil arching and fill deformation with different relative fill densities and fill heights. The test results show that the trapdoor settlements normalized by trapdoor width required for the soil arching ratios to reach minimum and ultimate values increased with fill height. In tests with dense fill, both the minimum and ultimate soil arching ratios were smaller compared to tests with loose fill at the same fill height. Two symmetrical slip surfaces developed from the trapdoor edges, with their inclination angles depended on the dilatation angle of the sand. The proposed Gaussian distribution function with fitting parameters well matched the measured fill settlement profile. In the dense fill tests, the settlement trough width and volume loss induced by trapdoor settlement gradually decreased with fill elevation due to its strong shear dilation behavior. Conversely, the loose fill exhibited weaker shear dilation behavior, resulting in a larger settlement region. The settlement trough width and volume loss ratio, derived from the measured fill deformation, can be used to predict the fill deformation, including the surface settlement.

Evaluation of Flexible Pavement Friction Coefficients: A Case Study of East-West Highway Near Mahendranagar City, Nepal

Friction is a crucial factor in highway engineering, as it affects the traction between a vehicle's wheels and the road surface. This traction significantly influences the movement, speed, and efficiency of vehicles on highways. The coefficient of friction depends on various factors, such as pavement materials, traffic volume, road age, temperature, and weather conditions. The Skid Resistance Test Method is adopted for the study, which involves using a Portable Skid Resistance Tester to measure the British Pendulum Number (BPN) and then calculating the coefficient of friction by dividing the BPN by 10. An evaluation of a 5 km stretch of the East-West highway near Mahendranagar Bazaar revealed a longitudinal coefficient of friction of 0.354 and a lateral coefficient of friction of 0.184 under both dry and wet conditions. These findings were relevant for design speeds ranging from 60 to 80 km/h and considered an Annual Average Daily Traffic (AADT) of 10,321 Passenger Car Units (PCU) during the year 2023/2024. The assessment also indicated a variance of 0.19% and a poor International Roughness Index (IRI) value of 2.05. These aggregates had specific gravities ranging from 2.6 to 2.67 and were sized at 13.2 mm. The application rate for the aggregates ranged from 12 to 15 kg per square meter. It is important to note that a higher coefficient of friction leads to reduced vehicle efficiency. Thus, it is crucial to carefully consider the coefficient of friction values and detailed specifications to ensure traffic safety and road integrity.

Hematological and performance adaptations to altitude training (2,320m) in elite middle-distance and distance swimmers.

Elite swimmers often schedule altitude training camps ahead of major events in an attempt to maximize performance. However, the relationships between altitude-induced hematological changes, markers of training adaptation, and performance changes in such context are unclear. This study assessed hematological status, markers of daily adaptation, and swimming performance in elite middle-distance and distance swimmers during a 22-day altitude training camp at 2,320m, 2weeks prior to World Championship qualification competition. Venous blood was obtained and total hemoglobin mass (tHbmass) measured (CO rebreathing) in 7 elite swimmers (4 females, 3 males) 8days before and on day 22 of the altitude camp. Resting heart rate, peripheral oxygen saturation, urinary specific gravity, body mass, fatigue and self-reported sleep duration and quality were monitored daily during the altitude camp. Swimming performance was assessed through a standardized set (6 sets of 4 maximal repetitions of 100m front crawl) on days 3, 10 and 17 of the camp, and at sea level competitions (200m-1,500m) immediately after the camp, and 2weeks later. tHbmass (+5.6 ± 3.3%; range: 2.1%-11.0%; p < 0.05), red blood cell count, hemoglobin concentration, hematocrit increased at the end of the training camp (p < 0.05). Performance at altitude improved throughout the camp (+1.4 ± 0.4%; range: 0.7%-2.5%; p < 0.05). No significant relationship was noted between hematological changes, the change in altitude performance and any of the monitored daily markers of adaptation during the camp. Compared to the swimmers' previous personal best, competition performances did not improve immediately (2.5% ± 1.9% slower times) and 2weeks after altitude (1.2% ± 1.4% slower times). The 22-day altitude training camp at 2,320m was beneficial for elite swimmers' tHbmass, hematological status and performance at altitude, but these benefits did not clearly translate into enhanced sea level performance immediately after or 2weeks later. The present study confirms the large inter-individual variability in hematological responses to altitude training, and that the improvement in performance at altitude and sea level may depend on factors other than the increase in tHbmass alone.

Low intestinal parasite prevalence in Finnish pet dogs and cats

BackgroundThis study updates the knowledge of current canine and feline endoparasitic prevalence in Finland. The previous studies reported intestinal worm prevalence of 5.9% in dogs and 7.1% in cats. We also determined the anthelmintic regime and background data of dogs and cats concerning Toxocara spp. infection. Altogether 664 canine and 379 feline (including 46 shelter cats’) fecal samples from over six-month-old animals were examined with quantitative Mini-FLOTAC method using zinc sulfate with a specific gravity of 1.35. Of these samples, 396 canine and 89 feline samples were analyzed using the Baermann method for nematode larvae. A fenbendazole efficacy study was conducted with 12 animals positive for Toxocara spp.ResultsEndoparasites were found in the feces of 3.5% of dogs, 3.6% of pet cats, and 41.3% of shelter cats. The most common findings in dogs were strongylid (1.7%) and Toxocara canis (0.9%) eggs. Trematode (0.4%), Eucoleus spp. (0.3%), taeniid (0.2%), and Trichuris vulpis (0.2%) eggs, and Cystoisospora spp. oocysts (0.2%) were also detected. One dog (0.2%) was positive for Crenosoma vulpis based on the Baermann method. Toxocara cati (3.3%), taeniid (0.6%), and trematode (0.3%) eggs were found in pet cats’ samples. The findings in shelter cat samples were T. cati (34.8%), Eucoleus spp. (13.0%), Cystoisospora spp. oocysts (10.9%), taeniids (8.7%), and Toxoplasma gondii/Hammondia hammondii oocysts (2.2%). Fenbendazole efficacy was adequate in all treated animals, except one cat. The background data revealed 31.2% of dogs being dewormed less than once a year or never. Under twelve-month-old dogs and dogs that were dewormed twice a year were most likely to be T. canis- infected. Shelter cats, male cats, mixed-breed cats, cats that were dewormed two to four times a year, and cats with a history of parasitic infections were most likely to be T. cati infected.ConclusionsThe prevalence of pet canine and feline intestinal parasites in Finland is low, particularly the Toxocara spp. prevalence. In free-roaming cats Eucoleus spp. is surprisingly prevalent. The parasite control strategies reported do not follow the ESCCAP guidelines. Typically, owners deworm their pets only once a year or less frequently.