Browsing by Author "Glaskova-Kuzmina, Tatjana"

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    Cyclic moisture sorption and its effects on the thermomechanical properties of epoxy and epoxy/MWCNT nanocomposite
    (2019) Glaskova-Kuzmina, Tatjana; Aniskevich, Andrey; Sevcenko, Jevgenijs; Borriello, Anna; Zarrelli, Mauro
    The aim of this work was to reveal the moisture absorption-desorption-resorption characteristics of epoxy and epoxy-based nanocomposites filled with different multiwall carbon nanotubes (MWCNTs) by investigating the reversibility of the moisture effect on their thermomechanical properties. Two types of MWCNTs with average diameters of 9.5 and 140 nm were used. For the neat epoxy and nanocomposite samples, the moisture absorption and resorption tests were performed in atmospheres with 47%, 73%, and 91% relative humidity at room temperature. Dynamic mechanical analysis was employed to evaluate the hygrothermal ageing effect for unconditioned and environmentally "aged" samples. It was found that moisture sorption was not fully reversible, and the extent of the irreversibility on thermomechanical properties was different for the epoxy and the nanocomposite. The addition of both types of MWCNTs to the epoxy resin reduced sorption characteristics for all sorption tests, improved the hygrothermal and reduced the swelling rate after the moisture absorption-desorption.
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    Effect of outdoor recreation activity on mental toughness of taekwondo athletes in competition period
    (2023-07-10) Boobani, Behnam; Grants, Juris; Boge, Iveta; Glaskova-Kuzmina, Tatjana; Bula-Biteniece, Inta; Jagiello, Wladyslaw; Litwiniuk, Artur; Latvian Academy of Sport Education (LASE)
    Background & Study Aim: Taekwondo mixes mental and physical training into a helpful leisure activity. The research focusing on the impact of taekwondo on psychological health, although limited, suggests it is associated with several positive outcomes. These include increased cognitive and affective self-regulation and prosocial behaviour in children and reduced aggressive behaviour in the youth and teenager population. The aim of this study is knowledge about the effect of outdoor recreation activity (walking in nature) on mental toughness components (confidence, control, and constancy) of taekwondo athletes during the competition period. Material & Methods: The participants of this study were 12 Latvian taekwondo athletes, including males (n = 6) and females (n = 6), aged 17-23. The experiment was held four weeks before the International Sweden Taekwondo Competition (2022). The participants had twelve sessions, including 40 minutes of outdoor recreation (walking in nature), in zones 1 and 2 (HR 101-141 bpm). The Sport Mental Toughness Questionnaire (SMTQ) measured the mental toughness components (confidence, constancy, and control). The data was analyzed using the mean, standard deviations, the Shapiro-Wilk test, and paired sample t-test. Results: The outdoor recreation activity (walking in nature) did not significantly affect the component of mental toughness (confidence t (11) = 0.451 as the p-value 0.837 >0.05, for constancy t (11) = −0.233; as the p-value 0.820 >0.05 and control t (11) = 0.117; as the p-value 0.909 >0.05) at the 5% level. Conclusions: Gender disparities exist in the mental toughness components of confidence, constancy, and control among Latvian taekwondo athletes. In particular, male athletes revealed higher average scores in confidence and constancy, with control scores remaining consistent across both male and female athletes. Furthermore, male athletes showed less variability in their confidence and constancy scores when compared to their female counterparts.
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    Effects of breathing exercises on young swimmers’ respiratory system parameters and performance
    (2024-09-24) Jakubovskis, Germans; Zuša, Anna; Solovjova, Jeļena; Boobani, Behnam; Glaskova-Kuzmina, Tatjana; Grants, Juris; Žīdens, Jānis; Latvian Academy of Sport Education (LASE)
    Breathing exercises are widely used to enhance respiratory function and athletic performance. This study aimed to assess the efficacy of a modified exercise regimen on respiratory parameters and its effect on the performance of young swimmers in competition. Thirty-one swimmers aged 16–17 from various clubs in Latvia were selected, comprising an experimental group (n = 15, height: 174.36 ± 7.85 cm, weight: 65.80 ± 9.35 kg, body mass index: 21.60 ± 1.54) and a control group (n = 16, height: 180.78 ± 7.05 cm, weight: 69.90 ± 6.49 kg, body mass index: 21.40 ± 1.56). With an average of eight years of experience, participants trained for approximately 43–45 weeks annually (pool and gym sessions), with an average training duration of 20 ± 2 hours per week. Measurements were conducted on days one and 30, involving spirometry and swimming performance assessment based on the best results in the freestyle 100-meter distance. The experiment consisted of a modified breathing exercise performed thrice weekly for four weeks. Significant improvements were observed in the experimental group compared to the control group in forced vital capacity (p = 0.02), peak inspiratory flow (p = 0.001), and performance (p = 0.001), with p-values < 0.05. However, no significant changes were noted in peak expiratory flow (p = 0.46 > 0.05). The findings indicate that modified breathing exercises effectively enhance respiratory parameters and performance in competitive swimmers.
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    Environmental Ageing and its Effect on Compressive Properties of Dental Composite
    (Kaunas University of Technology, 2019) Priladiša, Ksenija; Siliņš, Jurģis; Glaskova-Kuzmina, Tatjana; Proskurins, Jevgenijs; Bērziņa, Sandra; Jaunozola, Elizabete; Adlienė, Diana; Department of Physics; Department of Conservative Dentistry and Oral Health
    Dental composite materials (CM) are widely used in dentistry for restorations. The aim of this study was to determine how compressive properties of commercially available dental CM change in simulated intraoral conditions. The investigated material was 3M ESPE Filtek™ Ultimate A2 Enamel Shade that is widely used in dental clinic and preclinical studies for anterior and posterior restorations. First, the compressive properties of dental composite were determined in uncondensed state. The compressive modulus, strength and maximal deformation were evaluated from the stressstrain curves obtained for the prismatic CM specimens. The specimens were immersed in distilled water (pH = 6), water and vinegar solution (pH = 4), and alkaline mineral water (pH = 8) at 50 C until equilibrium moisture content. Then, the mechanical testing in compression was repeated. It was experimentally confirmed that the storage in simulated intraoral conditions caused a significant reduction of compressive properties of the dental CM, which can negatively influence the lifespan of the restoration. The strength and compressive modulus of the moistened samples were reduced by 27% and 25%, accordingly, but the maximal deformation was increased by 0.4% in comparison with the unconditioned samples. The CM stored in solution with pH = 8 had the highest elastic modulus and strength and the lowest maximal deformation in comparison with the CM stored in more acidic solutions (pH is 4 and 6), indicating to lower inner degradation phenomena of the dental CM.
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    Swimmers' shoulder injury prevention by correctly evaluate the technical errors
    (2024) Solovjova, Jeļena; Boobani, Behnam; Glaskova-Kuzmina, Tatjana; Jakubovskis, Germans; Grants, Juris; Žīdens, Jānis; Romero Ramos, Oscar; Litwiniuk, Artur; Rīga Stradiņš University
    Background and Study Aim: Shoulder pain is common in young swimmers. The aim of this study is the knowledge about the occurrence and reasons behind shoulder injuries and muscle imbalances on adolescent Latvian freestyle swimmers. Material and Methods: Thirty-six male competitive freestyle swimmers from 3 age groups (13-18 years old) from different clubs in Riga, Latvia, were selected. A questionnaire, a body posture assessment, and a video analysis were used to collect the data to find out the causes of shoulder injury and muscle imbalance. The data were analysed using the mean, standard deviations, Chi-square test, Analysis of Variance (ANOVA), and Post hoc Tukey's tests. Results: The questionnaire showed significant relationships between using small and big paddles and experiencing pain, especially in group two. The body posture analysis for points of external ear opening, acromion, radial point, outer points of the palm, highest point of the Iliac crest, trochanter, and upper end of fibula bone showed significant differences (p<0.05). The body deviation forward, the so-called ‘body falling’ forward, was in groups. The video analysis showed that the streamlined position is not achieved because the body is not in line. Conclusions: The coaches should correctly evaluate the swimmers' technical errors. The present study's findings illustrate the need for a validated shoulder injury prevention program in swimming.
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    The Tensile, Thermal and Flame-Retardant Properties of Polyetherimide and Polyetherketoneketone Processed via Fused Filament Fabrication
    (2024-02) Glaskova-Kuzmina, Tatjana; Dejus, Didzis; Jātnieks, Jānis; Vīndedze, Elīna; Bute, Irina; Sevcenko, Jevgenijs; Aniskevich, Andrey; Stankevich, Stanislav; Boobani, Behnam; Latvian Academy of Sport Education Platform
    Polymer materials are increasingly widely used in high-fire-risk applications, such as aviation interior components. This study aimed to compare the tensile, thermal, and flame-retardant properties of test samples made from ultra-performance materials, polyetherimide (PEI) and polyetherketoneketone (PEKK), using the fused filament fabrication process (FFF). The tensile tests were performed for these materials at different raster angles (0, 45, and 90°). The thermomechanical tests were done in the axial, perpendicular, and through-thickness directions to the extruded filaments. The impact of printing parameters on the flame retardancy of 3D-printed samples was investigated in vertical burn tests with varying specimen thicknesses and printing directions. Experimentally, it was testified that PEKK had better isotropic behaviour than PEI for mechanical performance, thermal expansion, and fire-resistant properties, which are essential in fabricating intricately shaped products.