Enhancement of Straw Bale Performance Using Gum Arabic

Background: The negative impacts of the construction industry are compelling arguments for embracing technology that contributes to carbon footprint reduction and resources conservation. Toward the achievement of objective 9 of the Sustainable Development Goals, the development of new building’s materials like straw bale has advanced in the construction industry. As demonstrated in the literature, straw bale is an eco-friendly material that presents many advantages, like its contribution towards a circular economy. However, it has low compressive strength and displays high displacement under compression load. So far, no attempt has been made in order to enhance the strength of straw bales. Objective: This study aimed to develop alternative material to straw bale using chopped straw stems mixed with a binder (gum Arabic) and determine its stress-strain characteristic. Methods: The manufacturing process of the new material involved the use of chopped straw and gum Arabic to form straw blocks. Results: Results obtained show that the compressive strength of straw block (1.25MPa) is greater than the strength of straw bale (0.02MPa). Also, the average displacement recorded during compression load on straw blocks (29mm) was 2.8 times smaller than the displacement in straw bale (80mm). In terms of shape and size, straw blocks match with conventional materials like cement or compressed block. This will facilitate their use in construction compared to straw bales that require skilled laborers for pre-compression and plastering. Conclusion: The use of gum arabic helps in holding straw stems together and forms a compact material with improved strength compared to straw bale. Performance improvement of the characteristics of load-bearing straw bale walls can be addressed by using straw blocks.

FBG Strain Monitoring of a Road Structure Reinforced with a Geosynthetic Mattress in Cases of Subsoil Deformation in Mining Activity Areas

This paper presents implementation of purpose-designed optical fibre Bragg grating (FBG) sensors intended for the monitoring of real values of strain in reinforced road structures in areas of mining activity. Two field test stations are described. The first enables analysis of the geogrid on concrete and ground subgrades. The second models the situation of subsoil deformation due to mining activity at different external loads. The paper presents a system of optical fibre sensors of strain and temperature dedicated for the investigated mattress. Laboratory tests were performed to determine the strain characteristic of the FBG sensor-geogrid system with respect to standard load. As a result, it was possible to establish the dependence of the geogrid strain on the forces occurring in it. This may be the basis for the analysis of the mining activity effect on right-of-way structures during precise strain measurements of a geogrid using FBG sensors embedded in it. The analysis of the results of measurements in the aspect of forecasted and actual static and dynamic effects of mining on the stability of a reinforced road structure is of key importance for detailed management of the road investment and for appropriate repair and modernization management of the road structure.

An Experimental Investigation into the Stress-Strain Characteristic under Static and Quasi-Static Loading for Partially Embedded Rock Bolts

This article deals with a static and quasi-static load using the maximum power of a hydraulic pump. Additionally, quasi-static coefficients for the partially embedded rock bolts were determined. The laboratory tests included 2.2 m long bolts, which were embedded segmentally on the lengths of 0.05 m, 0.3 m and 0.9 m and were tested. To fix the ribbed bolt rods in the steel cylinders, resin cartridges with a length of 0.45 m long were used. The main aim of the research was to determine the load-displacement characteristics. Knowing the bolt rod tensile mechanism, the points of failure in the material continuity were identified, on the basis of which stress-strain characteristics are made. Particular attention was paid to the definition of: tensile stress for the yield point (σ1), maximum stress (σ2), stress at failure (σ3), strain in the elastic range (ε1), strain for maximum stress (ε2) and strain corresponding to the failure (ε3).

Wyniki badań testu wytrzymałościowego próbki węgla w świetle badań tomograficznych

The study aimed to check the possibility of using computed tomography to observe fractures in coal samples before and after a triaxial compression test (TRX). The paper presents an innovative use of two specialized laboratory techniques: computed tomography and geomechanical triaxial compression test. Geomechanical tests were performed on a TRX-070, GCTS (USA) measuring triaxial system. A full stress-strain characteristic was recorded. Also, during the triaxial compression tests, the P and S wave velocities were measured and dynamic elastic moduli were determined. The results were compared. The sample was analyzed in two stages: CT measurement performed on raw coal sample (stage 1) and after the TRX test which destroyed the sample structure (stage 2). First, the sample was scanned reflecting the initial pores and microcracks system. The final stage represents the sample after the geomechanical test. A detailed pore structure analysis was performed for each of the stages. As a result of the proposed above-mentioned method, images of the pore structure were obtained after each step. The sample was analyzed for crack propagation and changes in the pore structure. The qualitative and quantitative interpretation was based on the determination of the number of voids, crack diameters, collapse angles, and comparison of the pore structure between the initial state of the sample and after the triaxial test. In the first stage (before the test), the largest object (identified as a microcrack) had a volume of approximately 16 mm3, after the sample was stress-tested (after the sample was destroyed), the largest identified object was about 15 times larger (240 mm3). It appeared that the coal sample was prone to fracturing in defined directions. Comprehensive research has demonstrated the legitimacy of using the proposed methodology to evaluate changes in the sample structure during the triaxial test.

Effect of IDT position parameters on SAW yarn tension sensor sensitivity

In this paper, the effect of the interdigital transducer (IDT) position parameters on the surface acoustic wave (SAW) yarn tension sensor sensitivity is investigated. The stress–strain characteristic of substrate was studied by the combination of finite element simulation and regression analysis method. According to this characteristic, the function relationship between the SAW yarn tension sensor sensitivity and the IDT position parameters was built using the regression analysis method. The monotonicity of the regression function was also given. On this basis, a novel sensitivity optimal scheme was proposed and solved by the quadratic programming method. Its solution demonstrates that the optimum sensitivity can be obtained when the IDT is 8.9 mm to the left side of the substrate and the IDT is 0.3 mm to the top edge of the substrate within a domain of the IDT position parameters. The SAW yarn tension sensor with corresponding IDT position parameters was fabricated to validate the correctness of the sensitivity optimal scheme. The measured results indicate that the SAW yarn tension sensor sensitivity can reach 813.69 Hz/g, which confirms that the novel scheme is effective.

Hereditary determined diving behaviour in rats as a factor of fitness

Background. Rats natural ability to swim and dive provides adaptation in the wildlife and is widely applied as an instrument in experimental physiology. Nevertheless theres little scientific evidence on diving behaviour in rats itself. Meanwhile this behavioural pattern might be a notable trait to shed light on functional features of the nervous system, the higher nervous activity structure and evolutional adaptability in animals, including inherited ones. Materials and methods. In the present work we compared the performance of the spontaneous diving behaviour in the Morris water maze and forced diving behaviour in the Extrapolation escape task in two selected rat strains genetically differing in the nervous system excitability threshold. Results. We found a greater extent and adaptive pattern of both types of the diving behaviour in the high-excitable LT strain. This may be due to such basic features of this strain as high exploratory activity and an increased level of fear reactions. It was also shown that the second, low-excitable HT rat strain, demonstrates maladaptive jumping behaviour in the Extrapolation escape task due to higher anxiety level in the stress conditions. Conclusion. Observed differences between two strains allow us to consider the diving behaviour performed by high-excitable rats an inherited strain characteristic resembling adaptive rat behaviours in the wild and look forward to investigate its genetic mechanisms.

Prolonged left ventricular contraction duration in apical segments as a marker of arrhythmic risk in patients with long QT syndrome

Aims Long QT syndrome (LQTS) is an inherited cardiac ion channelopathy predisposing to life-threatening ventricular arrhythmias and sudden cardiac death. The aim of this study was to investigate left ventricular mechanical abnormalities in LQTS patients and establish a potential role of strain as a marker of arrhythmic risk. Methods and results We included 47 patients with genetically confirmed LQTS (22 LQT1, 20 LQT2, 3 LQT3, and 2 SCN3B) and 25 healthy controls. A history of cardiac events was present in 30 LQTS subjects. Tissue Doppler and speckle tracking echocardiography were performed and contraction duration was measured by radial and longitudinal strain. The radial strain characteristic was subdivided into two planes — the basal and the apical. Left ventricular ejection fraction and global longitudinal strain were normal in LQTS patients. Mean contraction duration was longer in LQTS patients compared with controls in regard to basal radial strain (491 ± 57 vs. 437 ± 55 ms, P < 0.001), apical radial strain (450 ± 53 vs. 407 ± 53 ms, P = 0.002), and longitudinal strain (445 ± 34 vs. 423 ± 43 ms, P = 0.02). Moreover, contraction duration obtained from apical radial strain analysis was longer in symptomatic compared with asymptomatic LQTS mutation carriers (462 ± 49 vs. 429 ± 55 ms, P = 0.024), as well as in subject with mutations other than LQT1 considered to be at higher risk (468 ± 50 vs. 429 ± 49 ms, P = 0.01). Conclusion Myocardial contraction duration is prolonged for both radial and longitudinal directions in LQTS patients. Regional left ventricular function analysis may contribute to risk stratification. Apical radial deformation seems to select subjects at higher risk of arrhythmic events.