Duration Of Immersion Research Articles

Nanoparticle-Modified 3D-Printed Denture Base Resins: Influence of Denture Cleansers on the Color Stability and Surface Roughness In Vitro.

This study aimed to evaluate the influence of denture cleansers on the color, stability, and surface roughness of three-dimensional (3D)-printed denture base resins modified with zirconium dioxide nanoparticles (nano-ZrO2). A total of 440 specimens were fabricated using one heat-polymerized resin, and two 3D-printed resins (NextDent and ASIGA). According to the nano-ZrO2 content, the specimens for each resin were divided into five groups (0%, 0.5%wt, 1%wt, 3%wt, and 5%wt). Each concentration was divided into four subgroups (n = 10) based on the immersion solution (distilled water, sodium hypochlorite, Corega, and Fittydent) and immersion duration (360 and 720 days). The color changes (∆E00) and surface roughness (Ra, µm) of each specimen were measured at different time intervals (base line, 360 days, 720 days) using a spectrophotometer and a non-contact profilometer, respectively. The results were statistically analyzed using ANOVA and a post hoc Tukey's test (α = 0.05). Sodium hypochlorite showed the highest significant color change of all the denture base resins (p < 0.001). The average value of ΔE00 for sodium hypochlorite was significantly higher than the values for the other solutions (Fittydent, Corega, and water) (p < 0.001). Color stability was significantly affected by immersion time for all types of solutions except Corega (p < 0.001). All of the tested immersion solutions (distilled water, sodium hypochlorite, Corega, and Fittydent) showed a significant increase in the surface roughness of all the denture base resins (p < 0.05). Surface roughness was substantially increased by immersion time for all types of solution except Fittydent (p < 0.001). Denture cleansers can result in substantial color change and affect the surface roughness of unmodified and nanoparticle-modified denture base resins. Therefore, the selection of denture cleanser and appropriate types of material is critical for denture longevity.

Influence of Physical–Mechanical Strength and Water Absorption Capacity on Sawdust–Waste Paper–Recycled Plastic Hybrid Composite for Ceiling Tile Application

In recent times, there has been a notable surge in the interest in promoting environmentally conscious products, particularly within the building industry where the focus has shifted towards sustainable materials. In this study, as a sustainable building material, ceiling tiles have been fabricated as a composite board containing waste materials, namely waste paper, sawdust, recycled polyethylene terephthalate (PET), and epoxy resin, and characterized comprehensively through physical and mechanical tests, density, thickness swelling (TS), modulus of elasticity (MOE), modulus of rupture (MOR), and flexural strength (FS) for product stability. A total of nine composites were fabricated with different ratios through molding techniques, and the characterization results were compared to determine the optimized stable ratio of composite composition. The composition of 25% waste paper, 15% sawdust, 10% recycled PET, and 50% epoxy resin presented the maximum FS compared to the other composite ratios. Water absorption (WA) and thickness swelling were evaluated after immersion durations of 1–24 h. The findings revealed that as the density increased, the sawdust content within the matrix decreased from 25–35%. Concurrently, an increase in recycled PET content resulted in decreased water absorption and thickness swelling. Significantly, the MOE, MOR, and FS demonstrated optimal values at 864.256 N/mm2, 12.786 N/mm2, and 4.64 MPa, respectively. These observations represent the excellent qualities of this hybrid composite board, particularly in terms of sustainability, stability, and water absorption capacity. Moreover, its lightweight nature and ability to support ceiling loads further enhance its appeal for construction applications. This study not only advances the discourse on sustainable construction materials but also fosters opportunities for broader acceptance and innovation within the industry.

Effect of neem oil biodiesel on the surface and structural integrity of carbon steel alloy: Chromatographic, spectroscopic, and morphological investigations

This study explores the impacts of neem oil biodiesel (BD), which was produced and characterized using GC–MS, FTIR, and UV–Vis spectroscopic techniques to elucidate pure and corrosion-product neem oil BD at room temperature (25 °C) and different immersion durations of 0, 28, 42, and 56 days. The OM and SEM were also employed to study the surface, structural integrity, and interphase interaction between the BD and the carbon steel (C1020) before and after immersion for different durations. The dominant fatty acid (FA) group in both pure and corrosion-product neem oil BD was C18, with a total composition of 72.3 %, hence determining the nature of the BD interaction with the carbon steel. The study revealed that carbon steel (C1020) was susceptible to attacks by neem oil BD, and the duration of immersion had substantial influence on the surface morphology and structural integrity of the steel. It is therefore anticipated that this study will significantly advance the field of alternative fuel research.

Effect of beverages, denture cleanser and chlorhexidine gluconate on surface roughness of flexible denture base material: an in vitro study.

The purpose of the study was to evaluate and compare the effect of beverages, denture cleanser and chlorhexidine gluconate solution on surface roughness of flexible denture base material. Fifty flexible denture base resin specimens measuring 50±1mm in diameter and 0.5±0.05 mm in thickness were fabricated. The specimens were divided into five groups each containing ten specimens. The specimens were immersed in distilled water (Control group A); hot coffee (Group B); cold beverage (Group C); sodium perborate containing denture cleanser (Group D) and 2% chlorhexidine gluconate solution (Group E). The specimens were immersed for 10 min daily in mentioned solutions for up to 60 days. Surface roughness (Ra) was evaluated on the 1st, 20th and 60th day with the help of atomic force microscope. The statistical analysis was done using two-way ANOVA and Tukey's Post hoc test. The two- way ANOVA revealed that the average Ra values varied significantly depending on the type of solution used for immersion (p<0.001) and the duration of immersion (p<0.001). Variation in surface roughness with cold beverage was highest (p=0.001). On the 60th day the surface roughness of flexible denture base resin material was higher with cold beverage (0.184 μm) and denture cleanser (0.203 μm) than that of distilled water (0.052 μm) hot coffee (0.030 μm) and 2% chlorhexidine gluconate (0.068 μm). Exposure to cold beverage, which was acidic in nature and peroxide containing denture cleanser, produces much rougher surface in the thermoplastic polyamide flexible denture base resin specimens.

Pemanfaatan Eksrak Daun Kemangi (Ocimum basilicum L.) sebagai Alternatif Penurun Kadar Formalin pada Tahu Putih

&lt;em&gt;Tofu is one of the foods that are very liked by the people of Indonesia. However, because it is easily damaged, there are still many tofu manufacturers who use formalin with the aim of extending the shelf life of products and avoiding losses. Based on this, the purpose of this study was to test the effectiveness of basil leaf extract solution with different concentration variations and soaking duration in reducing formalin content in white tofu, as well as observing changes in white tofu protein levels before and after treatment. In addition, the study will also conduct sensory tests of color, suppleness and aroma. This research method applies a factorial Complete Randomized Design (RAL) involving two main factors. The first factor is the concentration of basil extract solution (K), which has three levels (K1:10%, K2:20%, and K3:30%). The second factor is the duration of immersion (L), which also has three levels (L1: 30 minutes, L2: 60 minutes, and L3: 90 minutes). Each variation of the treatment was repeated three times, and tests were carried out on formalin content, protein levels, and sensory tests covering aspects such as color, texture, and aroma. The findings of this study indicate that&lt;/em&gt;&lt;em&gt; the ability of the basil leaf extract solution to the highest decrease in formalin was 66.61% and an increase in protein content of 71.19%, namely in the treatment concentration of 30% basil leaf extract solution with immersion time 90 minutes (L3K3), with the results of the sensory test of texture 4.6 (like), color 4.1 (like), and aroma 3 (dislike).&lt;/em&gt;

Responses of Healthy Young and Older Adults to Short-Term Passive Heat Acclimation

Context: Aging is accompanied by a reduced capacity to dissipate heat. Heat acclimation has been shown to improve heat loss capacity in young healthy adults, yet few studies have investigated the capacity of older adults to adapt to repeated bouts of heat exposure, particularly when using a passive heat acclimation protocol. Furthermore, it remains unclear whether the magnitude of adaptations is affected by age. Objective and hypothesis: To compare physiological adaptations following 7 consecutive days of passive heat exposure between healthy young and older adults. We hypothesized that heat acclimation would enhance heat loss capacity in both groups but to a higher extent in young than in older adults. Methods: Fourteen healthy young (5F/9M, 27 ± 5 years) and 9 older adults (6F/3M, 66 ± 5 years) were exposed to passive heat stress with a water-perfused suit before (pre) and after (post) 7 consecutive days of immersion in 40°C water (~30 min to reach a rectal temperature of 38.5°C, followed by 60 min ≥38.5°C). During the pre/post heat stress test, mean body temperature was computed as 0.8 × esophageal temperature + 0.2 × mean skin temperature. Local sweat rate (LSR) and cutaneous vascular conductance (CVC) were measured at the forearm level. The mean body temperature onset thresholds of LSR and CVC were determined by segmented linear regression. During acclimation visits, rectal temperature and change in body mass were measured. Data are presented as means ± standard deviation or mean differences [95% confidence interval]. Results: Immersion duration (young: 90 ± 10, older: 92 ± 9 min, p=0.53), water temperature (young: 40.3 ± 0.3, older: 40.0 ± 0.5°C, p=0.09) and mean rectal temperature (young: 38.9 ± 0.1, older: 38.8 ± 0.1°C, p=0.07) during heat acclimation did not differ significantly between groups. In response to heat acclimation, rectal temperature decreased similarly ( p=0.36) in young (-0.33°C [-0.50, -0.16]) and older adults (-0.46°C [-0.68, -0.25]) from day 1 to day 7 whereas sweat rate increased to a higher extent ( p=0.05) in young (+511 mL/h [285, 738]) compared with older adults (+232 mL/h [112, 352]). Heat acclimation similarly reduced the mean body temperature onset threshold for CVC in young (-0.18°C [-0.32, -0.05]) and older adults (-0.19°C [-0.36, -0.02]) ( p=0.91), as well as, the mean body temperature onset threshold for LSR (young: -0.13°C [-0.25, -0.01], older: -0.15°C [-0.30, 0.00], p=0.84) during the pre/post heat stress test. Conclusion: These results suggest that passive heat acclimation improves heat loss capacity in young and older adults. However, age may blunt the increase in whole-body sweat rate that accompanies passive heat acclimation, but not other classical markers of human heat acclimation. Natural Sciences and Engineering Research Council of Canada. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Corrosion inhibition properties of sweet crude oil for carbon steel 1018 in NaCl solution

Abstract Aged oil pipeline production systems, historically designed without corrosion protection due to predominantly oil-wetted conditions, now face significant changes as increased water content in produced oil arises from field maturation. This work investigates the corrosion inhibition properties of sweet crude oil on carbon steel 1018 in a CO2-saturated NaCl solution using electrochemical testing (open circuit potential, polarization resistance, electrochemical impedance, potentiodynamic polarization) and surface characterization (SEM, EDS) techniques at 50 °C and pH 6. Carbon steel specimens were immersed in crude oil for durations ranging from 0 to 144 h before undergoing corrosion testing. Results showed that a 144-h immersion in crude oil led to an 88 % reduction in corrosion rate, comparable to the efficiency of standard quaternary ammonium-based inhibitors. Furthermore, a semi-empirical model predicting uniform CO2 corrosion rates for varying oil immersion durations is proposed and validated by comparing its predictions with experimental data from the electrochemical tests.

An integrated thermal sensation scale for estimating thermal strain in water

Acceptable definitions of thermal sensation for cold and hot water immersion do not exist. The use of subjective thermal sensation scales remains unsolved with broad psycho-physiological, and semantic implications. We hypothesize that perception of thermal sensation could be a valid and reliable indicator for thermal strain during exposure in water. We aimed to provide a theoretical background for behavioral thermoregulation and neurocognition to support an integrated thermal sensation scale for estimation of thermal load during head-out water immersion. This research used a mixed methods approach. Domains were identified and items were measured for thermal load to examine the content validity. Thereafter, we formed an integrated scale based on standard 10,551 of International Organization for Standardization (ISO). Finally, we conducted a pilot study for the face validation of the scale based on a 30 min head-out water immersion at 26 °C in healthy adults (females, n = 4; males, n = 4; age: 22.6 ± 8.0 years; body mass, 67.7 ± 9.5 kg; height, 169.0 ± 5.6 cm). We identified three aspects (environment, physiological and behavioral thermoregulation) and a total of 18 items, of whom eight items (water temperature, immersion duration, core temperature, skin temperature, body heat storage, shivering, thermal sensation, and thermal comfort) were acceptable based on terms of scale-level content validity index (S-CVI = 92 %). Conditions incorporated into our scale included: icy < 12 °C, cold 12–24 °C, cool 24–29 °C, neutral 29–38 °C, warm 38–43 °C, and hot > 43 °C. We found excellent face validity based on a reported homogenous cool feeling and physiological thermoregulatory responses. Our study revealed our model could reasonably characterize body thermal load though whole-body thermal sensation based on well-established thermoregulatory mechanisms during water immersion. Further research is needed to validate the accuracy of our behavioral model in a variety of water temperatures and in a larger sample size.

Pressure–temperature–time controls on shock vein formation within the Steen River impact structure

ABSTRACTThermodynamic modeling has been applied to determine pressure–temperature–time conditions leading to shock vein formation during the passage of a natural shock wave generated by hypervelocity impact. The approach is novel in considering both shock front and rarefaction pressures, as well as simultaneously forming and cooling the shock veins via two‐dimensional steady‐state conduction. Model results are tested using shock veins developed in granitic rocks that constitute the central uplift of the Steen River impact structure in Canada. Here, two variants of majoritic garnet were generated in different settings: (1) along the margins of shock veins due to pargasite and biotite breakdown (accompanied by maskelynite formation), and (2) within the originally molten shock vein matrix as newly grown crystals. We determine that during shock vein formation, the shock front pressure and wave width at the reconstructed sample location were 18 GPa and 830 m, respectively, with a dwell time of 160 ms. Intra‐vein melting at 2150°C was attained within 1 μs. Melt cooled to the solidus in 150 ms following shock front passage. Majoritic garnet formation was facilitated by the high temperatures realized within the veins as a result of frictional melting that accompanied shock loading. The calculated pressure–temperature–time (P–T–t) path provides constraints on the formation conditions of majoritic garnet at Steen River. The model results independently support previously determined P–T conditions based on mineral stability fields. The vein margin garnets (35–39 mole% majorite) and maskelynite formed first under higher P–T conditions for a longer duration (36 ms). The matrix garnets (11–22 mole% majorite) crystallized from melt under lower P–T conditions and for a shorter duration (22 ms). Our results indicate that shock pressure alone should not be used as a basis for shock classification. Instead, the interplay between pressure and temperature with time and the duration of shock immersion (dwell) must be considered.

Preparation and Characterization of Cellulose Derivatives from Agricultural Wastes

Background: Rice straw was pretreated with dilute alkaline and acid solutions to extract cellulose, which was then converted into cellulose acetate with acetic anhydride and phosphotungstic acid (H3PW12O40·6H2O). The concentration of KOH and the duration of immersion in acetic acid solution affected the removal of hemicellulose and lignin, and after pretreatment with 4% KOH and immersion in acetic acid for 5 hours, the treated rice straw contained 83wt.% cellulose. Phosphotungstic acid has been shown to be an excellent catalyst for the acetylation of rice straw cellulose. The degree of substitution (DS) values had a substantial effect on the solubility of cellulose acetate, and acetone-soluble cellulose acetate with DS values about 2.2 can be generated by varying the amount of phosphotungstic acid and acetylation duration. Objectives: The aim of the study was to evaluate the preparation and characterization of cellulose derivatives from agricultural wastes. Methods: This cross-sectional study was carried out in the Department of Communicable Diseases Control, Director General of Health Services, Dhaka, Bangladesh. For this investigation the rice plant straw was collected from Magura district region. The collected straws were then treated with 3 wt% nitric acid and 1.5 wt% NaOH solution separately. Statistical analyses of the results were be obtained by using window-based Microsoft Excel and Statistical Packages for Social Sciences (SPSS-24). Results: This study observed that the rice straw contained about 35.67% cellulose, 5.50% hemicellulose and 30.18 % α-cellulose. And the wheat straw contained about 43.99% cellulose, 7.30% hemicellulose and 36.70% α-cellulose. The degree of acetylation and degree of substitution of the synthesized cellulose acetate from rice straw were 39.046% and 2.413 respectively. On the other hand, the degree of acetylation and degree of substitution of the synthesized cellulose acetate from wheat straw were 40.79% and 2.59 respectively. ....

Investigation of chemically treated jute/kenaf/glass fiber with TiO2 nano-filler for tensile and impact characteristics

The essential objective of this work was to investigate the effect of silane treatment on the tensile and impact strength of composites made of jute/kenaf/glass fibers with the TiO2 nano-filler. This study also sought to optimize the factors connected with this treatment method. To develop and evaluate trials, the researchers used Response Surface Methodology (RSM) with central composite designs, emphasizing the optimization of silane concentration, immersion time, and nano-filler content. The researchers were able to effectively create quadratic models to forecast the tensile and impact strengths of the nano-composite throughout the silane treatment procedure. The adjustment of silane concentration, immersion duration, and nano-filler content discovered the best conditions for obtaining maximum tensile strength. The optimal values for silane concentration and immersion time have been identified to be 15 wt. % and 30 min, respectively. Considering these conditions, the composite’s tensile strength increased by 32.13% and its impact strength improved by 8.34% above the lowest values achieved from RSM optimization. The results demonstrate the practical value of silane treatment, notably in boosting tensile and impact strengths while enhancing interfacial adhesive among natural fibers and polymer matrices.

The Effect Dose and Soaking Time of Camellia sinensis Solution to the Egg Adhesion and Hatching of Pangasionodon hypophthalmus

Cultivation of Pangasianodon hypophthalmus is growing rapidly, but there was a problem with the egg’s adhesiveness. Overcome this problem given a tea solution that serves as a remove of Pangasianodon hypophthalmus egg adhesion. This study conducted on June 2022 at Fish Hatchery and Breeding Laboratory, Faculty of Fisheries and Marine, University of Riau. The purpose of this study was determining the effect of immersion eggs with different doses and immersion duration of the black tea (Camellia sinensis) solution on adhesion of Pangasianodon hypophthalmus eggs. This study used a Completely Randomized Design Factorial with 2 factors. The first factor was the dose (g/L) of the black tea with 4 levels; 0 (D0), 8 (D8), 10 (D10), and 12 (D12). The second factor was the immersion duration (minutes) with three levels of 3 (W3), 4 (W4), and 5 (W5). Pangasianodon hypophthalmus larvae reared for 7 days. Parameters measured were egg adhesion, fertilization rate, hatching rate, survival rate, and water quality. The result showed that the doses of C. sinensis solution had a significant effect (P&lt;0.05) on the degree of fertilization and hatching of Pangasianodon hypophthalmus eggs. The optimum treatment with a dose of 10 g/L and 4 minutes (D10W4) give increased eggs adhesion 5.99%, fertilization rate 94.13%, hatching rate 92.88%, and survival rate 96.99%. The water quality during the study were temperature 26.7-27.9OC, pH of larvae maintenance water 6.5-7.1 and DO 4.0-5.2 mg/L. There is an interaction between dose and immersion duration of C. sinensis solution to the egg adhesion and hatching eggs of Pangasianodon hypophthalmus.

Influence of impregnation time on TiO2 films sensitized with N719 and 2-Mercaptobenzothiazole: An electrochemical analysis

Dye sensitized solar cells (DSSC) are low-cost photovoltaic devices with easy production. They operate with a photoanode, a photocathode, and an electrolyte responsible for charge permeation within the cell. Recent research focus in DSSCs has aimed at enhancing their energy conversion properties, such as the insertion of new materials to reduce electronic recombination, utilization of gel electrolytes, dye synthesis, and studying cell assembly parameters. This study examined the effects of various immersion durations (6, 12, and 24 h) on TiO2 semiconductor films immersed in solutions containing charge carriers (N719 and 2-Mercaptobenzothiazole). To characterize the electrochemical properties, analyses such as current density versus potential curves (j-V), Electrochemical Impedance Spectroscopy (EIS), charge extraction, Intensity-Modulated Photovoltage (IMVS), and Photocurrent Spectroscopy (IMPS) were performed. It was found that the cell with 24 h of impregnation, presented a higher current density, consequently increasing efficiency (η = 5.76%). Impedance analyses showed that the 24-h samples facilitated charge transport, reducing cell resistance, consistent with charge extraction measurements. Lastly, IMPS and IMVS tests revealed that 24 h of immersion generated shorter collection times (τc = 0.016 ± 0.01) and longer electronic recombination times (τr = 0.07 ± 0.007), aiding the charge transport process.

Effects of Aqueous Solution and Immersion Duration on Spontaneous Combustion Characteristics of Weakly Caking Coal

ABSTRACT Coal spontaneous combustion (CSC) severely affects the development of the coal industry and threatens the safety of coal miners. This study investigated how immersing coal in aqueous solution affects the CSC risk and evaluated the effect of the immersion duration. Fourier transform infrared spectrometry and thermogravimetric−differential scanning calorimetry analysis were performed. Coal samples were immersed in water from an underground coalmine or in distilled water for 30 or 60 days. Changes in microscopic functional groups and thermokinetic behaviors were determined. Immersion in distilled water for 60 days led to 4.41%, 2.26%, and 6.25% smaller masses of C=O, –CH3, and free hydroxyl groups, respectively, relative to their levels in raw coal. Additionally, the characteristic temperatures T 4 , T 5 , and T 6 were 8.8%, 9.0%, and 9.2% lower, respectively, and the average apparent activation energy was 15.67% lower. Immersion in water from an underground coalmine for 60 days led to 5.68%, 2.58%, and 6.54% higher masses of C=O, –CH3, and free hydroxyl groups, respectively, and 12.8%, 13.0%, and 13.5% higher characteristic temperature, respectively; the average apparent activation energy was 20.43% lower. These findings suggest that the coal immersed in water from an underground coalmine was the most susceptible to CSC.

A First-Time Addition of Selenium to a Mg-Based Metal Matrix Composite for Biomedical Purposes

A magnesium-based metal matrix composite, Mg-5Se-2Zn-2SiO2, was synthesized using the Disintegrated Melt Deposition (DMD) method followed by hot extrusion. Elemental analysis revealed that the material experienced selenium loss which was attributed to the evaporation of selenium at high temperatures. Superior damping characteristics were exhibited while retaining similar Young’s modulus, and significant grain refinement also resulted in decisively superior mechanical properties such as hardness (32% increase), fracture strain (39% increase), as well as yield and ultimate compressive strength (157% and 54% increase, respectively). These were a consequence of SiO2 addition as well as presence of Mg2Si (and MgSe) intermetallic phases which were detected by X-ray characterization. Furthermore, while the material had lower corrosion resistance than pure magnesium, it retained acceptable corrosion resistance as well as structural integrity after the full immersion duration of 28 days. Overall, the material exhibits promising potential for applications in the biomedical field, especially in development of smaller and lighter implants where mechanical properties are paramount, with key lessons learned for the synthesis of Mg-materials containing selenium for the future.

Formation of Male Sex Tilapia Larvae (Oreochromis niloticus) Using Natural Methyltestosterone Hormone

Aims: Obtaining a productive tilapia, by changing the sex of the tilapia larvae into male monosex. This was achieved by determining the effect of the duration of administrating the natural methyltestosterone (MT) hormone on the male sex of tilapia using the Immersion method.&#x0D; Methodology: The study was conducted at the Northern Region Marine and Fisheries Service Branch, Wanayasa Freshwater Fish Seed Development Center, Purwakarta Regency, West Java Province, Indonesia. The experimental design used a completely randomized design (CRD) with 5 treatments and 3 replications. The study used the Immersion method where untreated tilapia and the four hormones tilapia. The treatments are as follows:&#x0D; A = untreated tilapia&#x0D; B = tilapia treated in 17a-MT (5h-100mg/L)&#x0D; C = tilapia treated in MT (5h-350mg/L)&#x0D; D = tilapia treated in MT (10h-350mg/L)&#x0D; E = tilapia treated in MT (15h-350mg/L)&#x0D; Results: Tilapia larvae used were aged 6 days after hatching and reared for 40 days, then the male and SR sex were observed. The results of this study showed that the duration of immersion of tilapia larvae using natural MT significantly affected the male tilapia which resulted in the highest male percentage at 15 h of immersion of 80.2%, then followed by 10-h immersion of 75.6% with the same SR value of about 90%.&#x0D; Conclusion: Administration of natural MT using cow testis meal by immersion method at different durations significantly affects male sexual development in 6-day-old tilapia larvae. Based on the obtained data analyses, the percentage of male tilapia in the 40-day experimental study shows the most effective duration in treatment E (15 h) with a measure of 350 mg/l, which is 80.2%. Further studies regarding the relationship between sex change and the growth of sex-changed fish as an effect of immersion duration.

Growth Response of Mucuna bracteata with the Application of Local Micro Organisms (LMO) of Banana Weevil

This research aims to determine the effect of concentration and duration immersion giving LOM banana weevil against the gowth of Mucuna bracteata. The research was conducted in the garden of Jalan Setia Bangun Pasar III, Sei Beras Sekata, Kecamatan sunggal, Kabupaten Deli Serdang, Sumatra utara and continued in the laboratory of the Indonesian Oil Palm Research Institute (IOPRI). This research was started in April-June 2020. This study used a randomized complete block design (RCBD) factorial. The first factor was the concentration of local microorganisms (LMO) of Banana Weevil consisting of 4 levels, namely: Without treatment, 15%, 30%, 45%. The second factor. The duration of immersion consists of 4 levels, namely: No immersion time, 15 minutes, 30 minutes, 45 minutes. Observation data were analyzed usingDuncan's Multiple Range Test with a significant 5%. The results showed that the LMO concentration of banana weevil was effective in increasing the gowth of the number of leaves 39.77, tendril length 83.14 cm, shoot fresh weight 28.54 g, and shoot dry weight 6.03 g. The duration of soaking had a significant effect on the highest number of leaves at week 3 (9.63 pieces). The interaction application of banana weevil concentration and soaking time affected the number of root nodules (40.50 gains) and root dry weight (0.73) g of theplant Mucuna bracteata.

Investigations on the Degradation Behavior of Processed FeMnSi-xCu Shape Memory Alloys.

A new functional Fe-30Mn-5Si-xCu (x = 1.5 and 2 wt%) biomaterial was obtained from the levitation induction melting process and evaluated as a biodegradable material. The degradation characteristics were assessed in vitro using immersion tests in simulated body fluid (SBF) at 37 ± 1 °C, evaluating mass loss, pH variation that occurred in the solution, open circuit potential (OCP), linear and cyclic potentiometry (LP and CP), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and nano-FTIR. To obtain plates as samples, the cast materials were thermo-mechanically processed by hot rolling. Dynamic mechanical analysis (DMA) was employed to evaluate the thermal properties of the smart material. Atomic force microscopy (AFM) was used to show the nanometric and microstructural changes during the hot rolling process and DMA solicitations. The type of corrosion identified was generalized corrosion, and over the first 3-5 days, an increase in mass was observed, caused by the compounds formed at the metal-solution interface. The formed compounds were identified mainly as oxides that passed into the immersion liquid. The degradation rate (DR) was obtained as a function of mass loss, sample surface area and immersion duration. The dynamic mechanical behavior and dimensions of the sample were evaluated after 14 days of immersion. The nanocompounds found on the surface after atmospheric corrosion and immersion in SBF were investigated with the Neaspec system using the nano-FTIR technique.

Disintegration Characteristics of Highly Weathered Granite under the Influence of Scouring

In South China, due to climatic factors, highly weathered granite is distributed across a large area and easily disintegrates after encountering water, causing many geological disasters and other problems. To determine the disintegration mechanism of highly weathered granite in South China, disintegration tests were carried out on highly weathered granite in the Fuzhou area under different immersion durations, cycle times, and flow rates, with the help of a self-designed disintegration test device. Moreover, the disintegration mechanism of the highly weathered granite was revealed using nuclear magnetic resonance (NMR) technology. The results demonstrated an increase in the cumulative relative disintegration with prolonged immersion time and the number of dry-wet cycles. Beyond a certain flow rate, the cumulative relative disintegration amount stabilized. There was a strong correlation between the steady disintegration rate and immersion time (or dry-wet cycles). The disintegration process of the highly weathered granite was divided into three stages: rapid, moderate, and stable disintegration. Notably, disintegration primarily occurred around the large pores. This study revealed that the variation in the immersion time (or wet-dry-scouring cycles) was fundamentally linked to changes in the relative volume of the large pores in the rock samples. These findings provide valuable insights for predicting and mitigating surface disasters on highly weathered granite slopes.

The effect of solution aggressiveness on the corrosion-induced degradation mechanism of Al-Cu-Li 2198 alloy

Investigation on the corrosion-induced degradation mechanisms of Al-Cu-Li 2198 alloy is critical for the aircraft maintenance protocol. This article aims to identify the corrosion-induced degradation mechanisms of AA2198-T8; three (3) different accelerated corrosion tests with electrolytes of various aggressiveness, namely sodium chloride (NaCl), Harisson’s and exfoliation corrosion (EXCO) solution were exploited. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and immersion tests were used in this context. The EIS analyses revealed that exploitation of different electrolytes essentially affects corrosion-degradation mechanism. Intergranular corrosion attack was found to dominate in EXCO solution, while transgranular attack was evident in both, 3.5 wt. % NaCl and Harrison’s solutions. Severe localized corrosion in Harrison’s solution led to higher degradation of elongation at fracture (Af) throughout immersion duration; EXCO exposure led to higher corrosion attack rate for the short exposure times (≤ 6 hours). Correlation between the different electrolytes regarding tensile ductility decrease was attempted through a linear coefficient for the initial, small exposure times; 1-hour EXCO exposure of AA2198-T8 was found to be equivalent to 107 hours exposure to 3.5 wt. % NaCl solution, while the respective correlation with Harrison’s solution showed that 1-hour EXCO exposure is equivalent to 27 hours Harrison exposure.