Experimental Laboratory Tests Research Articles

New design and construction of a mechanical gripping device with a telescopic link of a fruit harvesting robot

Abstract Gripping devices for harvesting fruits have such types of work as cutting, tearing and unscrewing. For apples, it is preferable to use slicing or unscrewing, while the fruit leg should not remain, damaging the apple during storage. In this article, we are developing a grab for harvesting apples. The gripper is used both for holding the fruit and for jamming, followed by unscrewing. One of the advantages is that the proposed method of collecting apples allows you not to waste time moving the manipulator from the tree to the basket, but only to grab and tear them off. The fruit enters the gripper device; after which it enters the fruit collection container through a rigid or flexible pipe. The gripper device is built on the basis of a ball-screw transmission, which is supplemented by a gear drive along the helical surface. This allows for rotation and rectilinear movement of the held fruit. The gripping device has a ratchet mechanism that allows you to fix the fruit. A mathematical model of the gripper device has been developed, which allows determining the torque of the engine depending on the position of the fingers. The parameters of the mechanism were optimized using a genetic algorithm, and the results are presented in the form of a Pareto set. A 3D model of the gripper device has been built and a layout has been developed using 3D printing. Experimental laboratory and field tests of the gripping device were carried out.

Effect of Non-Uniform Temperature Distribution on the Natural Frequency of Concrete Girder Bridges

Structural dynamic properties like frequencies and mode shapes have been widely adopted for bridge condition assessment and damage identification. One of the main challenges lies in environmental factors, particularly the varying temperature, which significantly influences the bridge’s natural frequencies. In some cases, the effect of temperature changes can be comparable to, or even exceed, the effect caused by damage, rendering the damage identification methods ineffective. This study investigates the influence of the cross-sectional non-uniform temperature distribution, as a result of surrounding environmental factors, on the frequency of concrete girder bridges. A theoretical analysis is conducted to derive the bridge’s frequencies considering the cross-sectional non-uniform temperature distribution. The upper and lower bounds of the frequencies are developed by using only the environmental temperature and the largest temperature gradient defined by codes. More importantly, the damage to the bridge can be detected if the frequencies exceed the bounds for a certain period. This approach is convenient and practical in real applications without embedding thermocouples in the main girder. Numerical simulations, laboratory experimental tests, and field measurements are carried out to validate the derived frequency considering the cross-sectional non-uniform temperature distribution as well as the upper and lower bounds of the frequency. In particular, the results of the Z24 bridge show that when the bridge is damaged, the measured frequency exceeds the bound continuously, verifying the capability of the developed upper and lower bounds to evaluate bridge conditions.

A thorough experimental assessment of THz-TDS plasma diagnostic techniques for nuclear fusion applications.

In this paper, the study of a plasma diagnostic system based on the THz time domain spectroscopy technique is presented. Such a system could potentially probe a large part of the electromagnetic spectrum currently covered by several other diagnostics in a single measurement. This feature, keeping in mind the basic requirements for plasma diagnostics in nuclear fusion experiments, such as robustness and hard environment applicability, as well as durability and low maintenance, makes the diagnostic of great interest. A conceptual design of the THz-TDS diagnostic has been developed, starting from the well-established classical microwave and far infrared plasma diagnostics landscape. The physical constraints and required instrumental characteristics have been studied and are described in detail here, together with the solutions available for each type of plasma measurement. Specific experimental laboratory tests of the different experimental configurations have been carried out, evaluating the capacity and potential of the novel diagnostic, together with the instrumental constraint, within the diagnostic parameter space.

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.

Comparison of Advanced Multivariable Control Techniques for Axial-Piston Pump

This article is devoted to a comparison of two advanced control techniques applied to the same plant. The plant is a certain type of axial-piston pump. A linear-quadratic (LQR) controller and an H-infinity (H∞) controller were synthesized to regulate the displacement volume of the pump. The classical solution to such a problem is to use a hydro-mechanical controller (by pressure, flow rate, or power) but, in the available sources, there are solutions that implement proportional-integral-derivative (PID), LQR, model predictive control (MPC), etc. Unlike a classical solution, in our case, the hydro-mechanical controller is replaced by an electro-hydraulic proportional valve, which receives a reference signal from an industrial microcontroller. It is used as the actuator of the pump swash plate. The pump swash plate swivel angle determines the displacement volume, respectively, and the flow rate of the pump. The microcontroller is capable of embedding various control algorithms with different structures and complexities. The developed LQR and H∞ controllers are compared in the simulation and real experiment conditions. For this purpose, the authors have developed a laboratory experimental test bench, enabling a real-time function of the control system via USB/CAN communication. Both controllers are compared under different pump loading modes. Also, this paper contributes an uncertain model of an axial-piston pump with proportional valve control that is obtained from experimental data. Based on this model, the robust stability of the closed-loop system is investigated by comparing the structure of a singular value (μ). The investigations show that both control systems achieved robust stability. Moreover, they can tolerate up to four times larger uncertainties than modeled ones. The system with the H∞ controller attenuates approximately at least 30 times the disturbances with frequency up to 1 rad/s while the system with the LQR controller attenuates at least 10 times the same disturbances.

Experimental study on shale-breaking of special-shaped cutter PDC bit

To enhance the drilling efficiency and extend the service life of PDC (Polycrystalline Diamond Composite) bits in shale formations, this study delves into the rock-breaking mechanisms of special-shaped cutters through a comprehensive experimental approach. This involves optimizing the cutter designs, conducting laboratory experiment and field testing. Among the various cutter geometries considered, concave, axe, planar, and triangular cutters are chosen as the focal points for unit rock-breaking experiments. These tests aim to assess their cutting loads and cutting specific energy to gain a deeper understanding of their performance characteristics. Based on experimental, the debris characteristics are analyzed. Based on the understanding of the shale-breaking characteristics of special-shaped cutters, field testing is performed using a novel PDC bit with a special-shaped cutter. Compared with planar cutters, the concave cutter and the triangular cutter generate lower cutting loads and cutting specific energy. Under identical conditions, the average cutting force and cutting specific energy of concave cutter at different cutting depths are reduced by 16.1% and 19.6% Specifically, the concave cutter generates the largest debris when operated under similar conditions, which is beneficial for increasing rock-breaking efficiency. Laboratory experiment indicate that compared to conventional drill bits, the novel drill bit experiences an increase in torque of approximately 9.8% with increasing WOB (weight on bit). Under high WOB, the ROP (rate of penetration) increases by about 75.4%, while the mechanical specific energy decreases by nearly 40%. Additionally, the novel bit vibration characteristics remain superior to conventional drill bits. Field testing shows that the average ROP of the novel bit and total footage drilled increase by up to 13.3% and 27.2%, respectively, in comparison with those for the conventional bit. The research results are helpful to speed up the efficiency of shale gas drilling.

Impact-Echo for Crack Detection in Concrete with Artificial Intelligence based on Supervised Deep Learning

Aging concrete infrastructure such as bridges and tunnels need to be appropriately maintained in their service life because these structures must be employed with ensured safety level. Inspection and maintenance with reasonable measures are typically operated for the reinforced concrete before severe damage and failure are developed. Especially, the crack propagation in concrete can significantly affect the structural integrity, durability and overall performance of structural elements. Effective maintenance strategies are required for material and structural assessment with detection and repair of cracks to prevent further deterioration. Identification of cracks in concrete is effectively operated to extend the service life of structures for mitigating the potential safety hazards and minimize the repair costs. In order to detect the cracks in the concrete structure member, non-destructive testing (NDT) system can be often introduced to satisfy the technical issues in terms of damage evaluation and estimation of repair condition. Currently, various NDT methods have been utilized for quantitative analysis of internal damage/defects using elastic wave method such as impact-echo method, focusing on reflection of P-wave in concrete as wave propagation behavior. In experimental laboratory tests, concrete specimens are usually prepared with interior damages (cracks) which are simulated as embedded plastic plate or styrofoam. In this study, starch- type polysaccharide sheet is used to form the simulated cracks in concrete specimen. This study aims at applying impact-echo method with AI (Artificial Intelligence) to identify the internal crack information based on the waveform characteristics obtained from the elastic wave propagation behavior. The waveform results are converted to frequency spectrum by FFT analysis. Consequently, it is found in this study that AI, which is employed by supervised deep learning models, successfully evaluates the data and displays the probability of crack existence in concrete. Since FFT is a powerful algorithm that quickly converts a signal from the time domain to the frequency domain, it gives efficient analysis to the impact echo method for crack detection with the application of AI system.

Wave Loads On Hydraulic Structures

Hydraulic structures are essential for flood protection, water management and navigation in coastal, delta and lake regions. Their importance will continue to grow in the coming years and decades, because of two main factors. Firstly, because of the consequences of climate change and sea level rise. Secondly, because of the continuous development and urbanization of coastal, delta and lake regions, with an increase in the value of the assets and activities in those locations combined with more strict safety requirements. Those factors will lead to the construction of a series of new hydraulic structures and the renovation of several existing structures around the world. Wave loads acting on such hydraulic structures are crucial for their design and safety assessment. This study addresses two different types of wave loads acting on hydraulic structures: confined wave impact loads and bimodal wave loads. To this end, a series of laboratory experimental test campaigns were carried out in a wave flume.

Physicochemical characterization of university campus’ wastewater for internal treatment system installation (Casablanca, Morocco)

Today, protecting water resources and their sustainable use has become an obligation of people and organizations. Wastewater management and reclamation are the most important solutions to protect these resources. This study aims to determine the wastewater physicochemical quality of the Faculty of Sciences Ben M'Sick (FSBM) (Casablanca, Morocco) to establish the appropriate system for their treatment and internal reclamation. The results show that averages of FSBM's wastewater temperature vary between 17.64 and 19.55 °C, 7.18 and 8.18 for pH, and 2.47 and 3.98 mS.cm-1 for electrical conductivity.. The COD, BOD5, and TSS average values oscillate respectively between 967.44-1,151.08 mg.L-1, 70.5-119.05 mg.L-1, and 223.64-1,659.74 mg.L-1, and those of total phosphorus between 2 and 3.99 mg.L-1. The determination of the biodegradability degree of the discharge, through the calculation of COD/BOD5, BOD5/COD, TSS/BOD5, COD/TP, COD/NH4+ ratios, and oxidizable matters (OM,) reveals that the FSBM's wastewater has a heterogeneous character with a high load of oxidizable matter difficult to biodegrade. Despite its low biodegradability, the FSBM’s wastewater could be treated using a biological treatment system, preceded by a physicochemical treatment to eliminate non-biodegradable chemical substances. Such a choice of wastewater treatment system requires prior experimental investigations and laboratory tests.

Stratified materials for aircraft structure: thermal effect of lightning impact by numerical simulations

This paper studies the effect of lightning impact on aircraft fuselage made of innovative Carbon Fibers Reinforced Composites (CFRC) panels, as an alternative to traditional metal structures. Metal layers are able to dissipate the current generated by lightning impacting the structure, whereas the multilayer CFRC panels are less conductive and therefore have limited capacity for current dissipation. This study presents a time-varying thermal simulation coupled with an electromagnetic simulation, considering different lightning currents that represent both short strokes (i.e., impulses), and long strokes (i.e., square pulses). In order to compare different stoke shapes, the temperature increment resulting from the lightning impact will be assessed through Finite Element Analysis. This approach allows for an assessment of the impact of different strokes on CFRC panels. The model serves as a starting point for future analyses aimed at comparing different technological solutions, beginning with experimental laboratory tests.

IN VIVO ACUTE TOXICITY TEST OF ALOIN EXTRACT ON CHICKEN WHITE MENCITES (Mus musculus)

Aloin has many benefits potential as a medicine. However, it is necessary to carry out toxicity tests on experimental animals as a pre-screening test. Toxic effect parameters were seen from changes in body weight, tremors, convulsions, salivation, weakness, walking backward, walking on the stomach, death, and levels of SGOT and SGPT in experimental animals. This study aims to evaluate the in vivo acute aloin toxicity test results in mice (Mus Musculus) regarding potential toxic symptoms and animal death. A sample of 27 mice were separated into three groups for this investigation: the control group, the treatment group I at a dose of 2500 µg/kg BW, and the treatment group II at an amount of 5000 µg/kg BW, and 5 mice in the preliminary test. This study employed a laboratory experimental test method using a pre-post control group design study. Based on observations of experimental animals, it concluded neither the preliminary test nor the toxicity test revealed any toxic signs. Neither the initial test nor the toxicity test resulted in any observed animal fatalities. Before and after aloin administration, changes in body weight were significantly different. Treatment group II, treatment group I, and the control group's SGOT levels were classified from highest to lowest, with subsequent values of 22.4 U/L, 21.9 U/L, and 19.9 U/L. The highest value of 35.7 U/L, 32.1 U/L, and 26.2 U/L in the treatment groups II, I, and the control group was used to rank the SGPT levels. There were no toxic symptoms and no mortality in experimental animals, so it can be concluded that aloin did not cause harmful effects in mice, so it was categorized as a pseudo-lethal dose.

Rotor resonance avoidance by continuous adjustment of support stiffness

This paper presents a method to reduce lateral vibration amplitudes in large rotating machines. The method is based on avoiding resonances by altering the natural frequencies of the rotor system at each rotating speed during operation. While many research papers have considered altering support stiffness during crossing critical speeds, continuous adjustment methods have received less attention. Continuous on-line adjustment of the natural frequencies of a rotor system is possible to a large range by adjusting the support stiffness of the bearing housings. The optimal foundation stiffness tuning policy can be defined utilizing a rotordynamic model or experimental measurements, effectively creating a resonance-free operating speed region, where vibrations are drastically reduced. It is shown through full-scale experimental laboratory tests, that the subcritical and supercritical response of the rotor system is significantly decreased during run-up and run-down with the optimal foundation stiffness tuning strategy. The developed method can be applied to reduce vibrations in any rotating machinery, where a variable foundation stiffness control can be installed. Moreover, this on-line foundation stiffness tuning strategy could also be applied in combination with resonance crossing methods involving stiffness manipulation.

Aloin Extract on Histopathological Features of Osteogenesis in Fractures of Rattus Norvegicus Wistar Strains

The process of bone repair after trauma or fracture will involve cells, signalling molecules, and processes that have been active during the remodelling process. The new study found that Aloin can promote the expression of osteogenic differentiation regulators, such as Bmp-1 (Bone morphogenetic protein 1) and Runx1 (Runt-related transcription factor 1) in MC3T3–E1 cells, where Runx1 is a transcription factor in osteogenic differentiation—knowing and analyzing aloin extract on the histopathological picture of osteogenesis in Wistar strain rattus norvegicus fractures. This type of research is a laboratory experimental test with a post-test-only control group design. The population number will be divided into four groups, namely positive control group (+), negative control (-), treatment group 1, and treatment group 1, with 14 samples using the Purposive Sampling technique. Univariate data analysis is presented as mean and standard deviation and one-way ANOVA statistical test. Data processing using computerized IBM version 15.0 of the SPSS program. Histopathological picture of osteogenesis in fractures of male rats (Rattus norvegicus) based on osteoblast values at least at K(-), which is 30.64, and K(+), which is 31.90. In the P1 group, the highest average osteoblast value was 39.58, and P1's was 38.14. The osteoclast value is obtained at least at K(-) and 8, and K(+) is 19.01. In the P1 group, the highest average osteoclast value was 16.73, and P1 was 11.70. Aloin extract did not affect the histopathological picture of osteogenesis in fractures of male rats (Rattus norvegicus) with a sig of >0.05.

Multi-objective Agent Model for XGBoost Controlled VFTO Simulator Based on Bayesian Optimization Algorithm

VFTO generated from GIS may cause interference and damage to terminal equipment on the primary and secondary sides, but experimental measures to evaluate the affected equipment and electromagnetic effects of the equipment through actual measurements are quite limited, so it is desired to build a VFTO simulator in the laboratory for experimental research and laboratory testing. Most of the current researches are conducted by building a true-type experimental platform for VFTO simulation, but this method has the disadvantages of large footprint, high cost and the scope of application can only simulate VFTO in a certain situation. Therefore, this paper establishes a broadband circuit model considering the pulse generator and the frequency domain equivalent transmission line model, and introduces the machine learning algorithm XGBoost to fit the agent model of the functional relationship between the design target and the structural parameters by establishing the sample data of the input circuit parameters and the output frequency waveform characteristics of the simulator, which is capable of dynamically adjusting the input parameters based on the waveform characteristics according to the changes of the target waveform, and ensures that a controllable waveform is obtained accurately in the laboratory the accuracy of obtaining controllable waveforms, thus realizing the output of controllable analog VFTO waveforms by changing the parameters of circuit components. Finally, the Bayesian optimization process is used for the hyper-parameter optimization of the XGBoost model, which has a fast convergence speed, and the characteristics of the output model are compared and analyzed, which verifies the feasibility and superiority of the proposed agent model as well as the multi-objective optimization method.

Photogrammetry-aided numerical seismic assessment of historical structures composed of adobe, stone and brick masonry. Application to the San Juan Bautista Church built on the Inca temple of Huaytará, Peru

This research presents a cost-effective surveying methodology to assist the seismic assessment of complex heritage buildings, based on terrestrial structure-from-motion (SfM) photogrammetry. The method was applied to the study of the seismic performance of the church of San Juan Bautista – Inca temple of Huaytará, Peru, an emblematic case study due to its complex architecture and coexistence of different construction materials. The geometrical model for the seismic assessment was developed with an error of less than 2 % using SfM photogrammetry. Non-linear static pushover analyses were performed on 3D FEM models of the nave and the towers to evaluate their individual response under seismic loading. Mechanical properties of different structural materials of the church were evaluated based on laboratory experimental tests on mortar and adobe, contemporary and ancient fired brick, Inca stone, colonial stone and rubble stone units. Non-linear pushover analyses were conducted in four directions perpendicular to the perimeter walls, and the response of the structure was compared with the seismic demand specified in Peruvian Standards. The simulations show that damage-prone areas are the western and eastern facades, with cracking at the connections between orthogonal walls, as well as at the interface of adobe masonry with Inca stone masonry. The towers exhibit similar seismic response, with lower strength capacities compared to the main nave. In this case, flexural overturning mechanisms and cracking at the interface between stone and adobe masonry were observed. The displacement-based seismic assessment using the N2 method shows that a peak ground acceleration of 0.21 g could lead to the collapse of the north and south facades of the main nave. The towers showed a much smaller capacity with PGA leading to collapse of approximately 0.09 g. Overall, this study contributes to the understanding of the seismic performance of the Huaytará-Huancavelica church, highlighting vulnerabilities and providing valuable information for its preservation and future interventions. Future investigations should focus on on-site tests that will allow the estimation of the effect of existing damage on the structural response and their incorporation in the numerical model.

The influence of viscous behavior and static shear stress on the cyclic strengths of plastic soil: a numerical study

An accurate understanding of the cyclic behavior of clays and plastic silts is important for system performance predictions during earthquake loading. This paper presents the results of a numerical investigation into the individual and combined influences of static shear stress and viscous strength gain on the cyclic resistance of clays and plastic silts. Using the viscoplastic constitutive model PM4SiltR implemented in the finite difference program FLAC 8.1, the cyclic behaviors of the plastic soils were simulated using single-element cyclic direct simple shear simulations. A parametric analysis was performed with different combinations of viscous strength gains and static shear stresses. The effects of static shear stress and viscous strength gain varied under monotonic and cyclic loading conditions. Numerical findings suggest empirical correlations developed using scant laboratory data may not accurately predict the reduction of cyclic strengths with increasing static shear stress. Furthermore, sizable magnitudes of monotonic viscous strength gains only produced a marginal increase in cyclic strengths. The findings from this study highlight the need for future experimental laboratory testing to validate the numerical findings, to improve the accuracy of performance predictions of geosystems constructed with clays and plastic silts during and following earthquake loading.

Performance Assessment of Overhead Conductors Subjected to Combined Thermal and Wind Loads

The overhead power conductors carry electricity power from distribution feeders to consumers, providing a necessary service. Aluminium Conductor Steel Reinforced (ACSR) and All Aluminium Conductors (AAC) are widely utilised in the Australian power distribution network. ACSR offers increased strength and conductivity by combining both steel and aluminium strands while AAC offers proper conductivity and lightweight powerlines. Due to factors like current flow, extremely elevated ambient temperatures, direct sunlight exposure, and short circuit currents, these conductors can be subjected to elevated temperature levels. Operating at higher temperatures can alter the mechanical characteristics of the conductor materials. Consequently, the mechanical strength of conductors diminishes when powerlines consistently operate under these conditions. Conductors are set up in various environmental conditions, resulting in different wind load impacts. While the temperature rise can be somewhat offset by these wind variations in terms of cable strength, wind action still introduces additional tensile stress in the conductor. Hence, this research aims to determine the combined effects of thermal and wind factors in the performance of ACSR and AAC cables. The laboratory experimental testing was performed to determine the decrease in the tensile strength of conductors under steady-state elevated temperature scenarios. The Australian standard prediction for wind and thermal conditions is considered for the calculation of the required strength in the conductors. Finally, the long-term safety performance of both ACSR and AAC cables was evaluated by considering the combined effect of temperature and wind effects.

Прогнозування залишкового ресурсу рейок залізничних доріг

The article is devoted to defining modern methods for assessing the residual resource of railway tracks. Since steel rails are one of the main components of railway transportation, predicting the service life and determining the residual resource of rails are important for ensuring the safe operation of railways. The main sectoral international and domestic regulatory documents have been analyzed, and the general state of the problem has been investigated. It has been estab-lished that the service life of railway tracks is determined mainly by the degree of dynamic loading, the number of initial defects during manufacture, the quality of steel rails, and the in-fluence of climatic and electromagnetic loads. Some methods and approaches to determining the residual resource in the world practice, which are based on experimental laboratory tests for the durability of decommissioned defective rails, have been studied. On the basis of the discov-ered mechanisms for the formation and development of defects, some specific recommenda-tions have been developed in order to increase the operational resource of railway tracks. How-ever, these methods do not take into account the stochastic aspects of the physics of degradation and destruction processes. Therefore, the most effective method for determining the residual resource of various objects is the probabilistic-physical method, which is based on the analysis of the dynamics of the change of the determining parameter. In accordance with the methodolo-gy of DSTU 8646:2016, given the data on the initial, current, and limited missed tonnage in which there are no rail failures, the calculation of the residual resource of railway rails is given. Calculations of the residual resource using the probabilistic-physical method on the example of heat-treated rails of passenger railways and using the relative values of the resource parameter have shown results that correspond to statistical data from the operation. The use of the method based on DM-distribution of failures helps to extend the life of rails and reduce operating costs by optimizing maintenance and repair processes.

Preference and Nutritional Content of Black Wheat Snack Bar with Hibiscus Flavor

The development of snack bar products using black wheat as the base ingredient and hibiscus flavoring is expected to yield new variations of snack bar products. This study aimed to: Determine the preference levels for the color, aroma, texture, and taste of black wheat snack bars with hibiscus flavor; 2 Determine the carbohydrate, fat, and fiber content of snack bars that are accepted by consumers. The research employed experimental methods, sensory evaluation, and laboratory testing. Three experimental designs were used, involving the addition of hibiscus powder at 5%, 10%, and 15% of the weight of black wheat flour. Data obtained from sensory evaluations were analyzed descriptively, while data from nutritional content test were compared with Recommended Dietary Allowances (RDAs). The research results indicated that the black wheat snack bar with 15% hibiscus powder addition was the most preferred product among the panelists, with 60% of panelists choosing this product. The nutritional content per 30g serving of the black wheat snack bar with hibiscus flavor included 21.9g of carbohydrates, 4.4g of fat, and 1.6g of fiber. Therefore, by consuming this snack bar, 7% of the RDA for carbohydrates, 7% of the RDA for fat, and 5% of the RDA for fiber can be met. In conclusion, this product can be recommended to individuals who want to maintain their health despite frequent snack consumption.

Antibacterial Assay of Green Tea (Camellia Sinensis L) Against the Growth of Enterococcus faecalis

Background: Enterococcus faecalis (E. faecalis) is often reported as an infectious agent in tooth root canals. Green tea leaves (Camellia sinesis L) contain active substances, namely catechins, which can act as an antibacterial. Research. Objective: To determine the antibacterial effectiveness of green tea extract (Camellia sinensis l) against the growth of Enterococcus faecalis bacteria. Methods: Researchers carry out tests in the laboratory, which are called laboratory experimental tests. The form of this research is Post-test Only Control Design. Researchers took samples using a purposive sampling technique with four treatments and six repetitions. The statistical test used is the Kruskal-Wallis test. Results: Based on the results of Kruskal Wallis, the p-value shows a value of 0.011 or a p-value of less than 0.05, which indicates that there is a significant difference between the Camellia sinensis L 25%, 50%, 75% treatment, and the positive control. Conclusion: Green tea extract (Camellia sinensis l) with concentrations of 25%, 50%, and 75% can inhibit E. faecalis' growth.