Test Object Research Articles

Memory-enhancing activity of verapamil in murine models of stress

Purpose: To evaluate the benefit of verapamil on stress-induced memory impairment in mice. Methods: Forty-eight (48) mice were used in this study. They were divided into two equal groups based on the two models of stress used in this study (sleep deprivation and hypoxia). Each model was further divided into 4 groups of six animals each. The mice in the sleep deprivation model were suspended on a platform above water while in the hypoxic model, mice were locked in an airless container for 20 min daily throughout the experiment. As for the intervention, 25 and 50 mg/kg verapamil were preadministered via the oral route to study groups, except the normal control group and negative control group in both models. After seven-day stress and intervention, the mice were subjected to behavioural tests (Y-maze and object recognition tests), biochemical assays (for acetylcholinesterase activity) and histochemical analysis. Results: Stress caused a significant (p < 0.05) impairment in the consolidation and retrieval of working and recognition memories. Also, acetylcholinesterase activity was significantly (p < 0.05) enhanced in the stressed groups when compared to control groups. Similarly, the histological analysis revealed a significant decline in population (p < 0.05), distribution and density of viable neurons in specific areas of the hippocampus and prefrontal cortex. These alterations were significantly (p < 0.05) attenuated in verapamil-treated groups almost in a dose-dependent pattern. Conclusion: Verapamil displays significant memory-enhancing effects in two (2) murine models of stress. Antihypertensives should therefore be considered a viable prospect in the management of stress-related memory disorders after additional studies have been done to establish the mechanisms of action.

Development of linear bearing equipment for modal testing of low-frequency weakly damped spacecraft structures

This article presents the results of a study of the bearing capacity and dissipative properties of an aerostatic linear bearing developed at JSC RESHETNEV for modal testing of complex structures. When selecting equipment for modal testing, the main condition is the requirement to minimize the distortions introduced into the determined dynamic characteristics: frequencies of natural vibration modes, the vibration modes themselves, as well as modal masses and damping coefficients. In other words, all equipment used for ground-based modal testing should ideally have zero added mass, stiffness and friction. The main systems containing elements that create dissipative forces that affect the determination of damping coefficients are systems for weight compensation and vibration excitation on natural modes. The weight compensation system usually contains either elastic elements or a system of guides with rolling or sliding bearings. If the former bring additional rigidity and mass to the test object, the latter bring mass and friction (dry or viscous), which increases the error in determining the dynamic characteristics. The excitation of vibrations on natural modes, in most cases, is carried out by electrodynamic vibrators consisting of a magnetization coil (or permanent magnet) and a movable coil moving in a magnetic gap. The movable coil is oriented in the magnetic gap using a special system containing either elastic elements or a linear guide bearing. Vibrators with elastic coil suspension elements cannot be used for modal tests of extended structures with low rigidity. The problem of creating an ideal bearing to replace classic linear (sliding or roller) ones arose during preparation for modal tests of the wing of a solar battery of a spacecraft (SC). Aerostatic bearings (supports) have virtually zero friction and sufficient load-bearing capacity, in which compressed air acts as a lubricant, eliminating physical contacts of the interacting surfaces. To confirm the possibility of using aerostatic bearings in equipment for conducting modal tests of extended structures with low frequencies of natural oscillations, comparative tests of a roller and aerostatic bearing were carried out. During the tests, optimal air flow parameters (nozzle diameter, operating pressure and gap) were selected, which ensure the required load-bearing capacity for radial forces and torques (bending and torsion). A comparative assessment of dissipative properties was carried out when measuring the attenuation parameters of single-mass harmonic oscillators, which include aerostatic and roller linear bearings. With a nozzle diameter of 0.6 mm, a working gap of 40 μm and a bearing input pressure of 1.0 bar, the logarithmic decrement of oscillations of the harmonic oscillator with an aerostatic bearing was 0.084, which is more than 28 times lower than the logarithmic decrement of oscillations of an oscillator with a roller bearing. The conducted studies confirmed the possibility of using the developed aerostatic bearing in test systems used in modal tests of large-sized transformable spacecraft structures.

Rhoifolin, baicalein 5,6-dimethyl ether and agathisflavone prevent amnesia induced in scopolamine zebrafish (Danio rerio) model by increasing the mRNA expression of bdnf, npy, egr-1, nfr2α, and creb1 genes

The increasing attention towards age-related diseases has generated significant interest in the concept of cognitive dysfunction associated with Alzheimer's disease (AD). Certain limitations are associated with the current therapies, and flavonoids have been reported to exhibit multiple biological activities and anti-AD effects in several AD models owing to their antioxidative, anti-inflammatory, and anti-amyloidogenic properties. In this study, we performed an initial in silico predictions of the pharmacokinetic properties of three flavonoids (rhoifolin, baicalein 5,6-dimethyl ether and agathisflavone). Subsequently, we evaluated the antiamnesic and antioxidant potential of flavonoids in concentrations of 1, 3, and 5 μg/L in scopolamine (100 μM)-induced amnesic zebrafish (Danio rerio) model. Zebrafish behavior was analyzed by novel tank diving test (NTT), Y-maze, and novel object recognition test (NOR). Acetylcholinesterase (AChE) activity, brain antioxidant status and the expression of bdnf, npy, egr1, nrf2α, creb1 genes, and CREB-1 protein level was measured to elucidate the underlying mechanism of action. Our flavonoids improved memory and decreased anxiety-like behavior of scopolamine-induced amnesia in zebrafish. Also, the studied flavonoids reduced AChE activity and brain oxidative stress and upregulated the gene expression, collectively contributing to neuroprotective properties. The results of our study add new perspectives on the properties of flavonoids to regulate the evolution of neurodegenerative diseases, especially AD, by modulating the expression of genes involved in the regulation of synaptic plasticity, axonal growth, and guidance, sympathetic and vagal transmission, the antioxidant response and cell proliferation and growth.

Wind tunnel testing and modelling of a rod-airfoil setup: validation and 3D acoustic imaging

This work revisits the rod-airfoil benchmark experiment from Jacob et al. (2004) with the aim of performing a detailed numerical validation in the nearfield and far field as well as to perform 3D acoustic imaging. The setup consists of a rod near the leading edge of a NACA-0012 airfoil and is placed in a semi-open wind tunnel in anechoic conditions. In addition to a far-field microphone array, the setup is equipped with two planar microphone arrays as well as wall-mounted microphones on the closed wind tunnel section and on the airfoil. The setup is modelled using a second-order finite volume method, and particular attention is devoted to including installation effects and sensor response properties in order to guarantee simulation accuracy. Validation examples are provided, including single microphone spectra as well as the acoustic field reconstructed on the test object by means of 3D acoustic imaging using the planar microphone arrays. Finally, the experimentally-validated numerical model is used as a means to gain further insight into the tested object. For instance, the model allows to separate acoustical and turbulent effects present in the sensors located within the flow section.

Nilai kekerasan permukaan pada beberapa tipe beton dengan agregat buatan dan korelasinya terhadap kuat tekan

Along with the development of technology to utilize waste in order to create sustainable concrete materials; therefore, this research tries to apply several artificial aggregates derived from concrete waste and fly ash. The test object was a standard concrete cylinder measuring 150 mm in diameter and 300 mm in height. Concrete was made from geopolymer coarse aggregate, treated recycled coarse aggregate, and conventional coarse aggregate. The surface hardness value was measured using a hammer test to obtain the rebound number (RN). Tests were also conducted on concrete with natural aggregate. The results show that the RN value of treated recycled coarse aggregate concrete is in the second place after normal aggregate concrete, followed by the RN value of conventional recycled coarse aggregate. Concrete with geopolymer coarse aggregate is concluded to be lightweight low strength concrete based on the RN value and compressive strength obtained. Furthermore, the relationship between RN values and compressive strength for other concretes is shown by the correlation of y = 0.837 x + 3.627, where y is the concrete compressive strength (MPa) and x is the surface hardness value (RN).

Monitoring of a fatigue test on a full-size railway steel bridge with acoustic emission

Within the frame of the Rail4Future project (https://www.rail4future.com) co-funded by the Austrian Research Promotion Agency, a railway steel bridge was removed from the track and transported to a workshop in one piece. Artificial defects were introduced at different sections of the bridge structure as per advice of the scientific project partners in order to initiate fatigue cracks in the course of the subsequent fatigue test. One objective of the fatigue test was to identify suitable measurement and testing techniques for monitoring of fatigue crack growth. Among other techniques utilised by different project partners, acoustic emission monitoring was applied by TÜV AUSTRIA. This contribution describes the preparation as well as the performance of the acoustic emission monitoring and the results obtained. It is shown that this non-destructive testing technique is suitable for fatigue crack monitoring.

Water Turbine Guide Blades Effect of Quartz Sand on Abrasion Rate

Abstract Hydroelectric power plants with the aim of being used to generate electrical energy are mostly operated in areas with sedimentation content which can cause wear and tear on the components of the hydropower plant. This activity is emphasized to determine the effect of quartz sand on the rate of abrasion on the guide vanes of the Francis type water turbine. This activity was carried out using a water turbine guide blade abrasion test tool with a guide blade test object made of SUS 304 stainless steel material. The results are presented quantitatively and qualitatively, the greater the concentration and diameter of the quartz sand particles, the water pressure and the angle given at the same time, the greater the rate of abrasion that occurs in the francis type water turbine guide vane. The highest abrasion rate was 5.10 (g/cm2 x hour) in the angle variation test with a constant Q and a water: sand ratio of 70%: 30%.

SAP 2000 Validates Deflection in Multilayer Test

Multilayer testing is one of the non-standard testing methods that has the potential to be developed in the future, so it requires special validation of its results. In this study, validation was carried out using SAP 2000 software, focusing on the calculation of downward curvature that occurs under the concrete layer. The study was conducted on test objects in closed conditions with certain dimensions. The test results showed that there was a difference between the downward curvature values ​​produced from multilayer testing and calculations with SAP 2000. The difference in downward curvature between the two methods was recorded at 15.29%. This difference indicates that more validation is needed to ensure the accuracy of the multilayer testing method in future structural applications.

Karakterisasi Produk Metalurgi Serbuk Berbahan Limbah Aluminium Paduan dan Kaca

Aluminum alloy and glass waste is often found in the business of making display racks. It is necessary to do research on the utilization of waste into useful products. This study aims to determine the hardness and compressive strength of objects made of a mixture of aluminum alloy and glass using the powder metallurgy method. The first stage was making aluminum and glass powders up to 100 mesh in size, the next stage was mixing the powders (mixing) with time variations of 70 minutes, 80 minutes and 90 minutes with a composition of 80% aluminum and 20% glass. Then manufacture of specimens with a compaction load of 8 tons. Furthermore, the sintering process at a temperature of 500 oC with time variations of 60 minutes, 90 minutes and 120 minutes, then tested hardness and compressive strength. The results obtained from the hardness test and compressive strength test showed the highest value for the test object with variations in the stirring time and sintering time of 90 minutes. Based on the two-way ANOVA analysis, the mixing time and sintering time obtained the values of Fcount>Ftable, so that the mixing time and sintering time have a significant effect on hardness and compressive strength.

Permeability and Dynamic Stability in Porous Asphalt Mixtures Using Cariphalte Asphalt and Gilsonite Additives

Porous asphalt mixture is a new generation of flexible pavement that allows water to seep into the top layer (wearing course) both vertically and horizontally. This condition is possible, because the gradation used has a coarse aggregate fraction of not less than 85% of the mixture volume. This layer uses an open gradation (open graded) which is spread over a layer of waterproof asphalt to prevent seepage into the road foundation. This porous asphalt layer can effectively provide a greater level of safety, especially during rainy times to prevent aqua-planing, resulting in rougher surface roughness and can reduce noise (noise reduction). In this research, a test will be carried out on porous asphalt with a mixture using Cariphalte modified asphalt and gilsonite as the added ingredient. Variations in asphalt content used are 4%, 5%, 6%, 7%, 8%. Determination of variations in levels of variation is based on research that has been conducted. This research involves analysis of calculation results based on experimental data from laboratory scale experiments including Marshall Testing, Immersion Index, Permeability, Slip Resistance, Dynamic Stability, and Resilient Modulus. The test results show that the smallest permeability value is in the 8% gilsonite mixture but it does not meet the requirements of AAPA 2004 so the mixture with the greatest stability value is used. From the results of dynamic stability testing, it shows that the mixture of test objects with a content of 7% gilsonite has a dynamic stability value of 5250 passes/mm at a temperature of 45°C and 3150 passes/mm at a temperature of 60°C.

Accelerated lithium-ion battery cycle lifetime testing by condition-based reference performance tests

Lifetime testing of lithium-ion batteries is time-consuming and costly. To reduce the time-to-market, application-specific accelerated lifetime tests are conducted. The test conditions must be carefully designed and controlled, both the test environment and load profile. During the lifetime test, measurable properties of the cell, most commonly the capacity and internal resistance, are tracked by a reference performance test (RPT). The frequency of RPTs is a variable of the number of test cycles or time. Setting the wrong frequency for the RPT results in either too many RPTs or, in the worst case, too few. To mitigate this issue, a test object capacity-driven approach has been developed. This new method is described and demonstrated in this article conducting the RPTs based on the cycling capacity of the cell. The method ensured the desired numbers of RPTs during the test period at the selected intervals corresponding to steps of 1% capacity loss. When compared to the most used traditional test method, using a fixed number of 200 cycles between RPTs, the method generated 44% more cycles over the initial 100 days.

Electrochemical Impedance Spectra Measurements and Analysis of Polymer Electrolyte Membrane Electrolysis on Short Stack

Transferring Electrochemical Impedance spectroscopy from fundamental research towards close to application systems allows direct insights into kinetics, transport processes and a state of health indication. Since such stacked systems are optimized for application comprehensive monitoring with reference electrodes is hardly possible. In addition, due to the high power consumption suitable measurement devices are hard to find and the results can only be used to a limited extent. In this work such a test object was set up and tested in different measurement configurations to investigate the reasons for the high noise ratio of the impedance measurement data at more than 200A. It was found that a series circuit consisting of a DC power supply, a high-precision impedance load and the test electrolyser has the least influence on the measurement result of all the methods tested. Finally, the impedance spectra were checked for interpretability using DRT and equivalent circuit fit.

Electrochemical Impedance Spectra Measurements and Analysis of Polymer Electrolyte Membrane Electrolysis on Short Stack

Transferring Electrochemical Impedance spectroscopy from fundamental research towards close to application systems allows direct insights into kinetics, transport processes and a state of health indication. Since such stacked systems are optimized for application comprehensive monitoring with reference electrodes is hardly possible. In addition, due to the high power consumption suitable measurement devices are hard to find and the results can only be used to a limited extent. In this work such a test object was set up and tested in different measurement configurations to investigate the reasons for the high noise ratio of the impedance measurement data at more than 200A. It was found that a series circuit consisting of a DC power supply, a high-precision impedance load and the test electrolyser has the least influence on the measurement result of all the methods tested. Finally, the impedance spectra were checked for interpretability using DRT and equivalent circuit fit.

Fault Diagnosis Method for Vacuum Contactor Based on Time-Frequency Graph Optimization Technique and ShuffleNetV2.

This paper presents a fault diagnosis method for a vacuum contactor using the generalized Stockwell transform (GST) of vibration signals. The objective is to solve the problem of low diagnostic performance efficiency caused by the inadequate feature extraction capability and the redundant pixels in the graph background. The proposed method is based on the time-frequency graph optimization technique and ShuffleNetV2 network. Firstly, vibration signals in different states are collected and converted into GST time-frequency graphs. Secondly, multi-resolution GST time-frequency graphs are generated to cover signal characteristics in all frequency bands by adjusting the GST Gaussian window width factor λ. The OTSU algorithm is then combined to crop the energy concentration area, and the size of these time-frequency graphs is optimized by 68.86%. Finally, considering the advantages of the channel split and channel shuffle methods, the ShuffleNetV2 network is adopted to improve the feature learning ability and identify fault categories. In this paper, the CKJ5-400/1140 vacuum contactor is taken as the test object. The fault recognition accuracy reaches 99.74%, and the single iteration time of model training is reduced by 19.42%.

Resistance of cellular variants of Nicotiana tabaccum L. plants to water stress

Aim. It has been established that resistance to some heavy metal cations is combined with resistance to osmotic stress. Thus, resistance to barium cations correlates with resistance to water stress. Therefore, the aim of the experiment was to compare the resistance of primary and secondary calli to modelled stresses. Methods. The object of testing was tobacco, a plant sensitive to water deficit. The level of resistance of the variants was assessed by the relative increase in fresh weight under osmotic stresses: (salinity, 25.0 g/l of sea water salts; sodium sulphate, water stress). Both concentrations are lethal for wild-type tobacco cell cultures. Results. Вa-resistant tobacco cell cultures were obtained. Tobacco callus were resistant to lethal modelled stresses. The Ba-resistant culture was developed on medium with the addition of sea water salts and sodium sulphate. Conclusions. The phenomenon of resistance was selected as a result of primary selection on the medium with heavy metal ions. The level of osmotic resistance did not decrease with increasing cultivation time.

Transcriptomic and Phenotypical Analysis of the Physiological Plasticity of Chamaecyparis hodginsii Roots under Different Nutrient Environments and Adjacent Plant Competition.

Chamaecyparis hodginsii seedlings undergo significant changes during growth due to different nutrient environments and adjacent plant competition, which is evident in the physiological plasticity changes in their roots. Therefore, in this experiment, 20 one-year-old elite C. hodginsii family seedlings were selected as the test objects, and the different nutrient environments and adjacent plant competition environments in nature were artificially simulated. Four nutrient environments (N heterogeneous nutrient environment, P heterogeneous nutrient environment, K heterogeneous nutrient environment, and homogeneous environment) and three planting patterns (single plant, conspecific neighbor, and heterospecific neighbor) were set up to determine the differences in root physiological indexes and plasticity of different family seedlings, and the families and treatment combinations with higher comprehensive evaluation were selected. The transcriptome sequencing of fine roots of C. hodginsii under different treatments was performed to analyze the differentially expressed genes. The results showed that the root activity, antioxidant enzyme activity, and nutrient element content of C. hodginsii seedlings in the N and P heterogeneous environments were higher than those in the homogeneous nutrient environment, while there was no significant difference between the K heterogeneous nutrient environment and the homogeneous environment, but MDA content was higher than that in other nutrient environments. The root activity and antioxidant enzyme activity in the competitive patterns were generally higher than those in the single plant and reached the peak in the heterospecific neighbor. The root physiological plasticity index of line 490 was the highest, but the comprehensive evaluation of root physiological indexes of lines 539 and 535 was better. The pattern with the highest comprehensive evaluation score was P heterogeneous nutrient environment × heterospecific neighbor. The effects of the N and P heterogeneous nutrient environments on root transcriptome genes were similar, which significantly increased DNA transcription and regulatory factor activity, while K heterogeneous nutrient environment focused on the regulation of root enzyme activity. The heterogeneous nutrient environment induces the conduction of hormone signals in the roots of C. hodginsii and induces the synthesis of phenylpropanone. The biosynthesis of phenylpropanone in the roots of C. hodginsii will increase significantly under competitive patterns. In summary, the N and P heterogeneous nutrient environments and the heterospecific neighbor can improve the root physiological indexes of C. hodginsii families, and the root physiological indexes of lines 539 and 535 are the best. The nutrient environment and competition pattern mainly affect the root system to transmit hormone signals to regulate enzyme activity.

Correcting the effect of temperature changes in the measurement results of dielectric response in power transformers as an arrhenius type dielectric with the help of artificial neural network

Polarization and Depolarization Current (PDC) and Frequency Domain Spectroscopy (FDS) measurements are common dielectric response tests in time and frequency domain that are widely used to diagnosis insulation status in power transformer companies. Numerous factors affect the PDC and FDS test results, which the most important of them is temperature variation. To accurately interpret the results of the dielectric response, the effect of temperature on the results in time and frequency domains, must be corrected. In this paper, firstly a 200 MVA transformer is selected as a test object and FDS and PDC tests are performed on it at different temperatures. Then, based on the FDS results performed on a transformer at different temperatures, the parameters of the insulation model have been estimated by using genetic algorithm (GA). Next, with the help of artificial neural network (ANN), the parameters of the insulation model, related to the different temperatures are transferred into the reference parameters. After that, the parameters of the transferred insulation model, the FDS curves are plotted and transferred to the reference temperature curve and the effect of temperature on them is compensated. By using the correlation of the time and frequency domain results, with the help of transferred insulation model parameters, the PDC results are also plotted and transmitted on the reference PDC curve. Finally, with such a method, the effect of temperature on the PDC results is compensated.

Analisis Karakteristik Material Baja dengan Metode Digital Image Correlation (DIC)

The use of steel materials in building construction opens new opportunities for sustainable development, as steel exhibits corrosion resistance, durability, and reliability in terms of strength and ductility. Digital Image Correlation (DIC) is non-contact technique in which digital images of the surface of a test object are captured using high-resolution cameras. This study conducted measurements of strain distribution on the specimen's surface using the DIC method throughout the entire tensile testing process. The study particularly focuses on examining changes in strain distribution during the melting phase and the local deformation phase leading to fracture. In this research, a comparison will be made between the load-displacement curves obtained from experimental laboratory testing and the results analyzed using the DIC method for SS400-grade steel material. Based on the results of the tensile test and DIC analysis that have been conducted, conclusions have been drawn in the research. The tensile test results of SS400 steel material with a thickness of 6 mm, 8 mm, 10 mm, and 12 mm meet the quality requirements in the tested specification standards, and the results of the force-displacement curve between the experimental test results and the DIC method obtained a minimum deviation with a value below 10%,. Therefore, it can be concluded that the DIC method exhibits a reasonably good level of accuracy, making it suitable for validating the results of experimental tests.

Optimization of water supply parameters for enhanced thermal uniformity in aquaculture ponds: An experimental study based on orthogonal experimental design

The temperature distribution in aquaculture ponds plays a crucial role in the rearing of fish larvae. To achieve a more uniform temperature distribution in the pond and alleviate the problem of thermal stratification, precise control of pond temperature is essential. A recirculating aquaculture pond was taken as the test object. Single-factor experiments and orthogonal experiments were conducted to comprehensively test the aquaculture pond's water supply pipe layout, bend angle, perforation rate, and environmental conditions. Three evaluation indicators were used to analyze the temperature distribution of the aquaculture pond under various water supply pipe structures, leading to the identification of optimal structural configurations. The optimal structure I, obtained from single-factor experiments, was determined to be 2.5 m, 50 %, and 60°, while the optimal structure II, derived from orthogonal experiments, was 1.25 m, 75 %, and 30°. Both optimized structures exhibited significant temperature fluctuations in the pond during the summer season. However, Structure II demonstrated the lowest average temperature difference in the winter season, indicating its superior adaptability during winter. Moreover, Structure II could provide higher temperatures for shallow areas with depths greater than 600 mm, making it more suitable for fish larvae cultivation. Additionally, local devices effectively decreased temperature variations by 17.5 % within the pond. Furthermore, energy consumption output was evaluated for different operational conditions. The results showed that Structure II had the lowest energy consumption output during the summer season. In contrast, during the winter season, the energy consumption output increased by approximately 12 %, indicating significant energy-saving potential in aquaculture ponds during winter.

Pengaruh Air Laut terhadap Kuat Tekan, Permeabilitas, dan Mikrostruktur Beton Geopolimer dengan Flyash dan Tanah Putih sebagai Pengganti Semen

The increasing infrastructure development of an area is sometimes located in an aggressive environment, one of which is in coastal areas so that direct contact with sea air cannot be avoided. This research aims to determine the effect of sea water on geopolymer concrete using fly ash and white soil as cement substitutes with testing parameters for compressive strength, permeability and microstructure. The test objects used were cylindrical in shape measuring 150x300 mm and 100x200 mm. The ratio of fly ash and white soil used was 85%:15% and the activator used was NaOH 8M and Na2SiO3 with a ratio of 1:2,5. The mixture proportion using a ratio of 1 fly ash: 1,497 sand: 2 split: 0,451 alkali activator with a mutual plan is 35 MPa. Tests were carried out after the concrete had gone through a curing process for 56 days, then the concrete was conditioned without soaking and with soaking for 28 days. Tests were carried out at concrete ages of 56 and 87 days. The test results show that geopolymer concrete with the influence of sea water has a higher compressive strength value and a smaller permeability coefficient compared to concrete without the influence of sea water. Microstructural testing of geopolymer concrete under the influence of sea air produces a matrix-shaped structure morphology that is denser with fewer pores compared to concrete without the influence of sea air.