Laboratory Experimental Research Research Articles

Sustainable and green removal of arsenic from crude tin via vacuum gasification–directional condensation

In the realm of high–tech industries, Sn has emerged as an indispensable strategic metal. However, the pyrometallurgical refining process of crude Sn is marred by the production of a substantial amount of hazardous solid waste, notably As–Al slag, posing a direct threat to the ecological safety of the production areas. This study delineates a novel process for the removal of As from crude Sn, employing vacuum gasification–directional condensation, corroborated by theoretical calculations and laboratory experimental research. Theoretically, at a system pressure ranging from 1–10 Pa, the initial volatilization temperatures of Sn and As exhibit significant variance. However, the formation of intermetallic compounds can induce Sn volatilization. Experimentally, the condensation temperature for As was predominantly within 331.7–484.7 K. During the vacuum gasification–directional condensation process, the presence of Sn4As3 intermetallic compounds impeded As volatilization. And under optimal conditions, the As content in the Sn product was recorded at 0.0053 %. Inspired from the calculations, a multistage vacuum distillation method was successfully proposed and achieved to remove As from crude tin. Typically, the total material recovery rate is 99.96 %, and the direct rate of Sn is 93.02 %. The total power consumption and emission of this process are better than the corresponding parameters of other treatment processes, which is a promising solution for the cleaning and effective removal of As.

Experimental laboratory models as tools for understanding modifiable dementia risk.

Experimental laboratory research has an important role to play in dementia prevention. Mechanisms underlying modifiable risk factors for dementia are promising targets for dementia prevention but are difficult to investigate in human populations due to technological constraints and confounds. Therefore, controlled laboratory experiments in models such as transgenic rodents, invertebrates and in vitro cultured cells are increasingly used to investigate dementia risk factors and test strategies which target them to prevent dementia. This review provides an overview of experimental research into 15 established and putative modifiable dementia risk factors: less early-life education, hearing loss, depression, social isolation, life stress, hypertension, obesity, diabetes, physical inactivity, heavy alcohol use, smoking, air pollution, anesthetic exposure, traumatic brain injury, and disordered sleep. It explores how experimental models have been, and can be, used to address questions about modifiable dementia risk and prevention that cannot readily be addressed in human studies. HIGHLIGHTS: Modifiable dementia risk factors are promising targets for dementia prevention. Interrogation of mechanisms underlying dementia risk is difficult in human populations. Studies using diverse experimental models are revealing modifiable dementia risk mechanisms. We review experimental research into 15 modifiable dementia risk factors. Laboratory science can contribute uniquely to dementia prevention.

Antibacterial activity in vitro investigation of eucheuma cottonii extract from aru islands against pathogenic bacteria

Red algae Eucheuma cottonii is one of the potential marine biodiversity that provides added value in the pharmaceutical and cosmetic fields and is known to have antibacterial compounds. Research focusing on the potential of E. cottonii as an antibacterial is still limited, particularly when it comes to the Aru Islands. This study aimed to measure the antibacterial activity of E. cottonii against pathogenic bacteria including E. coli and S. aereus at several concentrations and to determine the best concentration for inhibiting these two pathogenic bacteria. The study was true experimental laboratory research with a post-test-only controlled group design. Antibacterial tests using the disc diffusion method and phytochemical tests were carried out. This study revealed that E. cottonii could be able to inhibit S. aureus ranging from 0.27±0.03 – 2.1±0.14 at a concentration of 50%-100%, and 0.17±0.05 – 0.45 ± 0.03 against E. coli at a concentration of 80-100%. Meanwhile, saponins and flavonoids were two bioactive compounds found through phytochemical testing. The study concluded that the n-hexane extract of E. cottonii was able to inhibit the growth of E. coli and S. aureus, even with a weak inhibition category. This study recommends that improvements are needed in the E. cottonii extraction process to maximize the antibacterial properties of E. cottonii.

Studi eksperimental kinerja mesin TV-1 (engine research test) berbahan bakar campuran diesel-biodiesel

This research is a laboratory experimental research that uses research testing machines. Using biodiesel fuel, a mixture of oil and diesel fuel. The composition of the biodiesel mixture used in this research was B35, B40, and B50 into diesel fuel in millilitres (ml). Tests were carried out by varying the load and compression ratio (CR), namely loads of 3 kg, 5 kg, 8 kg, and compression ratios of 14, 16, and 18. Data collection used observation techniques using tables to record the study results obtained. By using descriptive analysis techniques in the form of graphs and tables to make it easier to find out the study results. The results of the study from the engine performance research tests obtained were that performance increased with increasing loading at low compression ratios with the addition of biodiesel to diesel fuel, while at high compression ratios, the greatest power was obtained from B35 mixed fuel. However, the lowest fuel consumption in the mixture composition is the B35 mixture. Meanwhile, the lowest emission density opacity obtained was in the mixture of B35 and B40 biodiesel.

The Antibacterial Effect of Red Dragon Fruit Peel Extract (Hylocereus Polyrhizus) Against The Growth of Bacterium Enterococcus Faecalis

Enterococcus faecalis is the main cause of periradicular infections after root canal treatment. It is currently being encouraged by using natural ingredients as an alternative tooth root canal irrigation substance, one of which is the peel of red dragon fruit (Hylocereus polyrhizus) containing flavonoids, tannins, and alkaloids. To identify the antibacterial effects of the peel of red dragon fruit extract (Hylocereus polyrhizus) on the growth of the bacterium Enterococcus faecalis. This experimental laboratory research in vitro using the bacterium Enterococcus faecalis ATCC 2921. The method used was ditch-diffusion on Mueller Hinton media to continue measuring a radical zone using a sliding caliper. The peel of red dragon fruit extract (Hylocereus polyrhizus) consists of several concentrations: 20%, 40%, 60%, 80%, and 100% based on V1N1 = V2N2. Datas were tested statistically using the One way-Anova test, starting with a normality test using the Shapiro-Wilk test, then a homogenity test, and continued with a post hoc test using the Least Significant Difference (LSD) to identify whether the results showed a significant difference in the antibacterial power of dragon fruit peel extract against Enterococcus faecalis.: All tested concentrations were antibacterial against Enterococcus faecalis bacteria growth. The highest concentration of antibacterial against was 100% (p <0.05). Peel of red dragon fruit extract (Hylocereus polyrhizus) had an antibacterial effect on the growth of Enterococcus faecalis bacteria

Antibacterial potential of Biduri leaf extract (Calotropis gigantea) against the growth of Streptococcus mutans ATCC 35668 colonies: an experimental laboratory

ABSTRACTIntroduction: Caries is an oral cavity infection that attacks the hard tissue of the teeth. Caries are caused by cariogenic bacteria such as Streptococcus mutans (S.mutans). S.mutans plays a role in the process of biofilm and plaque build up. One alternative ingredient that has antibacterial properties is Biduri leaves (Calotropis gigantea). The research aimed to analyze the antibacterial potential of Biduri leaf extract on the growth of S.mutans colonies. Methods: This type of research is a laboratory experimental research in vitro using the post-test-only control group design method. The antibacterial test used the colony counting method. The extraction process used the maceration method for 1 day with a shaker. The concentrations used were concentrations of 20, 40, and 60%. Control (+) used 0.2% chlorhexidine and control (-) used distilled water. Incubation process was for 24 hours. Counting the growth of S.mutans colonies using a colony counter was carried out by three observers. Data analysis used the Kruskal-Wallis test followed by the Mann-Whitney test. Results: The results showed that there was a significant difference in the growth of S.mutans (p<0.05) after being exposed to Biduri leaf extract at a concentration of 20, 40, and 60%. Conclusion: The Biduri leaf extract has antibacterial potential against S.mutans at concentrations of 20, 40, and 60%, and the best concentration in reducing the growth of S.mutans colonies is the concentration of 60%.KeywordsAntibacterial, Calotropis gigantea, 0.2% chlorhexidine, colony counting, Streptococcus mutans

Isolation and Characterization of Lactic Acid Bacteria From Sago Wastewater As Antibacterial

Background: Foodborne diseases are infections of the gastrointestinal tract caused by food containing microbiological agents and usually, these infections affect groups of individuals who have low immune systems. Lactic acid bacteria (LAB)are bacillus-shaped Gram-positive bacteria that work by inhibiting pathogenic bacteria that cause foodborne diseases. Maluku is a region in Indonesia rich in sago production. Sago ihur (Metroxylon sylvestre) and tuni (Metroxylon rumphii) are types of sago commonly found in Maluku. Sago is rich in carbohydrates and therefore has the opportunity to produce LAB. This study aimed to isolate and characterize LAB from sago wastewater was a laboratory experimental research with descriptive method using primary data. Methods: Bacterial isolation was carried out using a selective media. Characterization carried out by macroscopicly characterization by observing shape, margin, elevation, pigmentation, appearance, optical properties, and texture. Microscopic characterization was performed using Gram and spore staining. Results: The results of this study showed that five bacterial isolates (I1, I2, T3, T4, and I5) were successfully isolated in a round shape, flat edges, yellowish white color (not pigmented), shiny appearance, and mucoid texture, but isolate T3 showed a raised elevation and translucent to light (transparent), while for other isolates it was convex and translucent, and non-spore forming gram positive. Conclusion: Antibacterial tests against S. aureus and E. coli showed no inhibition zones. LAB isolates from sago wastewater showed no significant antibacterial effect

Effects of Borassus flabellifer L. fruit seed coat on HSC-3 cell line

Background: The seed coat of Borassus flabellifer L. fruit contains antioxidants that can neutralize the toxic effects of free radicals and can fight DNA damage due to exposure to oxidative stress. The extract of B. flabellifer is proven to have cytotoxic effects and can inhibit the growth of several types of cancer cells such as HeLa cell lines. Objective: To determine the cytotoxicity effect of extract of B. flabellifer L. fruit seed coat against HSC-3 cell line. Methods: Laboratory experimental research was conducted using HSC-3 cell lines treated with B. flabellifer L. fruit seed coat extract at concentrations of 93.75 µg/mL, 187.5 µg/mL, 375 µg/mL, 750 µg/mL, and 1,500 µg/mL, negative control DMEM-FBS 20%, and positive control anti cancer drugs Doxorubicin 3 µM. HSC-3 cell line cytotoxicity assay was performed using CCK-8 reagent. Micro plate reader at 450 nm wavelength was used to determine the viability of HSC-3 cell lines by measuring the optical density of formazan. Results: B. flabellifer fruit L. seed coat extract was able to reduce viability and was cytotoxic to HSC-3 cell lines at concentrations of 93.75 µg/mL, 187.5 µg/mL, 375 µg/mL, 750 µg/mL, and 1,500 µg/mL, with an IC50 value of 141.9 µg/mL. Conclusion: B. flabellifer L. fruit seed coat extract can reduce the ability of HSC-3 cell line cancer cells to survive by inhibiting cell proliferation due to its cytotoxicity effect.

Effect of Toxoplasma Infection Dosage on Igg, Igm, Fetus Weight and Body Length, and Necrosis of Placenta and Fetal Heart

One of the most prevalent zoonotic illnesses in the world, toxoplasmosis, affects both humans and animals and is caused by the parasite Toxoplasma gondii. The infection will trigger the immune system to increase antibody production. This study aims to determine the dose of toxoplasma that causes necrosis in rats placental and fetal hearts. This study was laboratory experimental research with a Randomized Control Trial (RCT). The study design used a post-test only with a control group design. The Ig G variable obtained from the control group (CG) and treatment group 3 (TG3) is the most significant because the mean value difference was the largest (176.56). The Ig M variable obtained from the control group with treatment group 3 (TG3) is the most significant because the mean value difference is the largest (33.47). The fetus weight variable obtained from the control group with treatment group 3 (TG3) is the most significant because the mean value difference is the largest (2.6). The body length variable obtained from the control group between treatment group 3 (TG3) is the most significant because the mean value difference is the largest (1.26). There was a significant difference in placental tissue necrosis (p = 0.034) and heart (p = 0.025) between the control group (CG) and treatment group 3 (TG3). Therefore, there was a significant difference in Ig G, Ig M, fetus weight, body length, placental tissue necrosis, and fetal heart at the 10³ dose compared to the 102, 101, and normal doses.

Inhibitory potential of turmeric extract (Curcuma domestica Val.) toward the growth of Streptococcus gordonii bacteria

Introduction: Dental caries is a disease caused by damage to the hard tissue of the teeth by the metabolic activity of bacteria, one of which is the cariogenic bacteria Streptococcus gordonii. Turmeric is one of the most popular spices in Asia with good antibacterial capabilities. Turmeric content such as curcumin can inhibit bacterial growth. Objective: To determine the potential inhibitory power of turmeric extract on the growth of Streptococcus gordonii. Method: The research is carried out using in vitro laboratory experimental analytical research with a posttest only control group design. The research determined the effect of turmeric extract concentrations of 50%, 12.5%, 3.125%, 0.78% against Streptococcus gordonii bacteria on agar media. Statistical data analysis is carried out to determine whether there was a significant effect of turmeric extract on the inhibition of the growth of Streptococcus gordonii bacteria in each treatment. Results: There was a significant influence on the test results between groups of turmeric extract concentration on the inhibitory power of Streptococcus gordonii bacteria. Conclusion: Turmeric extract can inhibit the growth of Streptococcus gordonii. Higher concentration of turmeric rhizome extract which can inhibit the growth of Streptococcus gordonii bacteria more effectively.

Changes in compressive strength of Ti-6Al-4V during immersion in artificial saliva at pH 6.5 and dynamic treatment

Background: Dental implant materials have been developed over time and become an alternative to dental treatment. One of the materials, Ti-6Al-4V, is widely used. The pH saliva in the oral cavity can change due to various factors, thereby affecting the implants durability. This research was conducted to determine the durability of Ti-6Al-4V implants based on their effect on the oral environment. Objective: To analyze change of compressive strength of Ti-6Al-4V in artificial saliva pH 6.5 and dynamic stress treatment. Material and Methods: Laboratory experimental and analytic research was conducted with 27 Ti-6Al-4V implant samples, which were classified into 3 groups, each consisting of 9 samples, including those with no treatment, aquades solution, and artificial saliva with pH of 6.5. In the negative control group, the samples were treated dynamically, while the samples in the positive control group were not treated. Samples from the treatment group were subjected to a dynamic test in accordance with ISO 14801 standards while being immersed in artificial saliva with pH of 6.5. Thereafter, a compression test was conducted on each group. A one-way ANOVA test was used to analyze the comparison of the results. Results: The results of data analysis using One-Way ANOVA found a significance value of less than 0.05 (Sig<0.05). This shows that there is no significant difference between each group and the average maximum compression value was T1<T3<T2. Conclusion: There were no significant changes in compressive strength of Ti-6Al-4V after immersion test with artificial saliva pH 6.5 and dynamic treatment.

Compressive strength of Ti-6Al-A4 after immersion test with artificial saliva pH 8.0 and dynamic testing

Dental implants are an alternative dental treatment that has been developed with one of the chosen materials, called Ti-6Al-4V. The pH environment in the oral cavity is expected not to affect the Ti-6Al-4V implant’s durability. The aim of this research was to analyze the change in compressive strength of the Ti-6Al-4V implant after dynamic and immersion tests with artificial saliva at pH 8.0. The method that we used in this research is laboratory experimental and analytic research was conducted with 27 Ti- 6Al-4V implant samples, which were classified into three groups as research subjects. Each group consists of 9 samples, including those with no treatment (UT), aquades solution (DW), and artificial saliva with a pH of 8.0 (AS). In the negative control group, the samples were treated dynamically in accordance with the ISO 14801 standard, while the samples in the positive control group were not treated. Samples from the treatment group were subjected to a dynamic test in accordance with ISO 14801 standards while being immersed in artificial saliva with a pH of 8.0. Thereafter, a compression test was conducted on the three sample groups. A one- way ANOVA test was used to analyze the comparison of treatment results. The result for this research is the immersed Ti-6Al-4V implant in artificial saliva and dynamic testing with a stress of 50 N, 2 million load cycles, and a frequency of 12 Hz do not significantly impact the compressive strength of each Ti-6Al- 4V sample. In Conclusion, the dynamic treatment along with the immersion test on artificial saliva at pH of 8.0 seemed to have no effect on the compressive strength of each sample.

Cell phone radiation effect on osteocalcin and bone alkaline phosphatase

Background: Electromagnetic fields are forces associated with moving electric charges and have electrical, magnetic components and contain electromagnetic energy, one of which is radio frequency (RF) energy which is commonly used in telecommunications. Cell phones are one of the RF electromagnetic radiation devices that can emit 90-2450 MHz waves and are often placed near the head. The human body works like an electromagnetic field in that each cell has its own electrical circuit characteristics. As the number of electromagnetic radiation devices in the environment increases, the electromagnetic balance in the human body may be disturbed by the magnetic waves produced by cell phones. Electromagnetic radiation is known to have the ability to induce oxidative stress, which is characterized by the accumulation of reactive oxygen species (ROS) in tissues. The accumulation of ROS in the body leads to osteoblast cell death. Osteoblasts are needed for mineralization of the extracellular matrix during bone growth. Therefore, bone growth is not optimal and can caused malocclusion. Purpose: This study aims to evaluate the relationship between electromagnetic radiation and osteocalcin and bone alkaline phosphatase (BALP) serum levels. Methods: Experimental laboratory research with a pre- and post-control group design approach was carried out on 12 Rattus norvegicus Wistar strain. Osteocalcin and BALP serum levels were calculated before and after treatment. This study used the t-test as a comparative study (p<0.05). Results: There are significant differences in osteocalcin and BALP values between the treatment groups before and after treatment. Conclusion: Cell phone radiations (electromagnetic field exposure) reduce osteocalcin and BALP serum levels.

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.

A Assessment of stone ash as a lightweight concrete constituent material with the addition of bestmittel additives

Technological advances in the field of building construction have developed very rapidly, so we need a construction technology that can reduce exploitation of nature. Utilization of stone ash is one of the new material alternatives in concrete mixtures with the addition of the bestmittel additive to accelerate drying in concrete. The purpose of this study is to determine the aggregate characteristics, specific gravity and compressive strength of concrete. The method used is laboratory experimental research with variations in stone ash samples of 5%, 10% and 15% to the weight of sand with the addition of 0.6% bestmittell additive to the weight of cement. The results showed that stone ash and bestmittell additives affect the characteristics of the concrete. The value of specific gravity increases with increasing percentage of stone ash, namely 1898.77 kg/m3 in normal concrete, 1911.35 kg/m3 of 5% stone ash concrete, 1922.34 kg/m3 of 10% stone ash concrete and 1927.06 kg/m3 m3 on 10% stone ash concrete. The compressive strength value of characteristic for the compositions AB 5%, AB 10% and AB 15% are 10.08 Mpa, 10.35 Mpa and 10.88 Mpa respectively, an increase compared to normal AB 0% concrete, namely 9.03 Mpa at 28 days.

Bacteria Pseudomonas taiwanensis as a decomposing agent of peat fiber

Efforts are needed to accelerate the decomposition of peat fiber to reduce the fiber content through bioaugmentation using Pseudomonas taiwanensis bacteria so that it can reduce the high-water content of peat fiber. The research aimed to determine the effect of adding Pseudomonas taiwanensis bacteria on the decomposition of peat fiber. This research is a laboratory experimental research. The research sampling location was in Bereng Bengkel Village, Palangkaraya. The parameters observed included fiber content, fiber size distribution, and peat fiber decomposition speed following the Peat Testing Manual. The research instrument was an observation sheet for fiber content, size distribution, and peat fiber decomposition speed. Research data was analyzed using descriptive statistical analysis. The results showed that adding 15% Pseudomonas taiwanensis bacteria with a curing period of 28 days in fibrous peat resulted in the highest reduction in fiber content, from the initial condition of 61.14% to 12.33%. This variation also shows a decrease in coarse and medium fiber content and a significant increase in fine fiber content. The decomposition rate for this variation shows good consistency. The conclusion was that adding 15% Pseudomonas taiwanensis bacteria with a curing period of 28 days showed optimal results in accelerating the decomposition of peat fiber through the bioaugmentation method.

The Effect of Solvent Concentration Against Specific and Non Specific Parameters of Standardization: Ethanolic Extract of Papaya Seed (Carica papaya Linn.)

Papaya plants (Carica papaya L.) can be used as traditional medicine. The parts of the plant commonly used as medicine are the seeds and leaves. Assurance of the quality of the extract obtained needs to be carried out by testing specific and non-specific parameters. The aim of the study was to determine the effect of the percentage of ethanol solvent concentration on specific parameters (organoleptic, phytochemical screening, and total phenolic content) and non-specific parameters (moisture content, ash content, and specific gravity) of papaya seed extract (Carica papaya L.). This type of laboratory experimental qualitative research was done to determine the effect of the percentage of ethanol solvent concentration (70% and 95%) on specific and non-specific parameters. Specific and non-specific parameter testing is based on work procedures listed in the Indonesian Herbal Pharmacopoeia. The results of testing the specific parameters on organoleptics showed no difference in the extract obtained, which was viscous and dark brown in color with a characteristic odor. Based on qualitative phytochemical screening, 70% ethanol extract contains alkaloids, flavonoids, tannins, and saponins. However, the 95% ethanol extract was only positive for alkaloids, flavonoids, and tannins. The phenolic content test of 70% ethanol and 95% ethanol extracts was 4.31 ± 0.65 mg GAE/g and 2.69 ± 0.41 mg GAE/g, respectively (Sig 0.022 < 0.05). Extract non-specific parameter test results. The ash content test for 70% and 95% ethanol extracts was 9.5% ± 0.21% w/w and 8.5% ± 0.06% w/w (Sig 0.043 < 0.05). The respective water contents were 8.7 ± 0.11% w/w and 9.7 ± 0.26% w/w (Sig 0.046 < 0.05). The specific gravity of each obtained was 0.88 ± 0.006 % g/ml and 0.75 ± 0.006% g/ml (Sig 0.043 < 0.05). The conclusion of this study is that the concentrations of 70% ethanol and 95% ethanol in papaya seed ethanol extract have an effect on specific parameters, namely the measurement of total phenolic content. While the non-specific parameters affect the water content, total ash content, and specific gravity.

Antibacterial effect of ethanol extract of moringa oleifera seeds against enterococcus faecalis atcc 29212

Background: One of the important stages in endodontic treatment is root canal irrigation. The most widely used irrigant is sodium hypochlorite (NaOCl), but it is toxic to periapical tissue. Irrigant solutions from natural ingredients that have antibacterial potential are needed, one of which is Moringa oleifera seeds. Bacteria that are often found persistent after root canal treatment are Enterococcus faecalis. The purpose of this study was to determine the antibacterial effect of the ethanol extract of M. oleifera seeds at concentrations of 37.5%, 50%, 67.5% and 75% against E. faecalis.Method: Experimental laboratory research with post-test only control group design was carried out with 4 times replication. Antibacterial activity was tested against E. faecalis ATCC 29212 using paper disc diffusion method on Mueller Hinton Agar (MHA) media. The diameter of the inhibition zone formed was measured. Data were analysed by one-way ANOVA followed by LSD.Result: The 2.5% NaOCl group produced the largest inhibition zone of 16.38 ± 0.95 mm, followed by the 75% extract group of 13.51 ± 0.49 mm, and the smallest was the 37.5% extract group of 4.42 ± 0.27 mm. The negative control (DMSO) did not produce an inhibition zone. The increase in the concentration of the ethanolic extract of M. oleifera seeds resulted in significantly better inhibiting the growth of E. faecalis (p<0.05).Conclusion: Ethanol extract of M. oleifera seeds at 37.5%, 50%, 62.5% and 75% had antibacterial effects against E. faecalis, with the 75% had the strongest antibacterial effect compared to other extract concentrations.

Effect of Immersion Duration in Coffee Beverage on Colour Stability of Polymethyl Methacrylate Denture Base Reinforced with 1% Chitosan Nanogel (Laboratory Study)

Hot polymerized acrylic resin (RAPP) denture bases have several weaknesses, so RAPP requires reinforcing materials, one of which is chitosan. Extrinsic factors cause color changes in RAPP. The aim of this research was to determine the effect of soaking time for RAPP denture base material after adding 1% chitosan nanogel in coffee solution on color stability. Laboratory experimental research, using 16 cylindrical plates, diameter 15 x 2 mm (n = 8 from each group). There are 2 groups, the water-soaked group and the coffee drink group. Color stability measurements were carried out before and after soaking for 1, 2, 3, 4, and 7 days. The color stability of the samples was tested using a colorimeter and color changes were analyzed using the Kruskall-Wallis and Mann-Withney tests. There is an effect of soaking time for RAPP denture base material on color stability with a value of p = 0.0001. Soaking the RAPP denture base material after adding 1% chitosan nanogel in a coffee solution for color stability for 4 days is still clinically acceptable.

MATHEMATICAL MODELS OF CHEMICAL PROCESSES WITH VARIABLE CHARACTERISTICS

The article discusses the construction of mathematical models of complex chemical processes when different factors act on the result of a chemical reaction at different points in time. The method of least squares is used. This material can be used to teach university students in the disciplines of Mathematical Statistics, Numerical Methods, General Technologies of Food Production, Food Chemistry, etc. Applications from the analysis of experimental research models and laboratory testing of innovative technologies for the development of different types of galusa can be supported by incoming students in the chemical engineering program. Examples from the analysis of experimental research models of laboratory tests of new acid components for a carbonate collector can be applied in the training of students in the Chemical Engineering educational program.