Acrylic Surface Research Articles

New insights from nanoscale in-depth investigation into wettability modification in oil-wet porous media

In the context of fluid-surface studies of oil reservoirs, wettability alteration plays an important role, especially in carbonate reservoirs. This investigation, utilizing molecular dynamics simulation, delves into the effect of oil movement during interactions with brine ions. The calculation of adsorption energy, radial distribution function, diffusion coefficient, and configurational changes of the NaCl brine molecules allowed for an examination of the role of ions in oil movement from an oil-wet calcite surface. Findings indicate that the polarity of oil has a marked influence on oil detachment, as evidenced by the more than 30% adsorption energy for the acrylic acid system compared to the decane system. The diffusion coefficient of Na[Formula: see text] ions in the acrylic acid system was found to be five times as high as in the decane system. Configuration changes showed that brine ions are more active — in a regular eight shape — in interacting with the acrylic acid-wet surface as opposed to the decane-wet surface. The hierarchical significance of oil polarity [Formula: see text] brine ions [Formula: see text] mineral surface in altering the wettability of the system demonstrates the significance of sodium ions in the presence of the polar oil component. The findings greatly contribute to the development of effective Smart Water flooding technology.

Effect of Tantalum Oxide Nanpowder on Heat Cure Acrylic Resin Thermal Conductivity and Surface Roughness

The main problem with heat cure acrylic is their poor thermal conductivity and their roughness. This study aims at evaluating the effect of tantalum oxide nanopowder on the thermal conductivity and surface roughness of heat cure acrylic resin. Material and Method: The Intention was to create a total of (60) specimens. Twenty samples were made without additives (control), and 40 had been made with tantalum oxide at two different amounts (1 %, 1.5%). Results: the thermal conductivity tests showed non-significant difference among studied groups. The surface roughness tests showed highly significant difference among studied groups. when tantalum oxide had added to heat cure acrylic at two different amounts (1%, 1.5%). Conclusion: adding tantalum oxide increases the thermal conductivity and decreases the surface roughness of the two experimental groups.

Effect of Different Cleaning Regimes on Biofilm Formation of Acrylic-Based Removable Orthodontic Appliance: A Randomized Clinical Trial.

This study aimed to evaluate the effects of different cleaning regimes of acrylic-based removable orthodontic appliances on bacterial biofilm formation and whether the surface modification, i.e., polished acrylic fitting surface, reduces biofilm formation. This double-blind, parallel, randomized clinical trial involved thirty-nine orthodontic patients indicated for removable orthodontic appliances. The patients were allocated into three groups according to the cleaning method: brushing with a denture brush and chlorhexidine (CHX) toothpaste, Lacalut cleaning tablet, and a combination of both cleaning methods. Each patient wore an upper removable appliance containing eight wells fitted with eight detachable acrylic tiles (four polished and four unpolished) for seven days. Five types of oral microbiota were evaluated using selective growth media and biochemical tests. The biofilm cleaning efficacy was assessed using the colony-forming unit (CFU) and scanning electron microscopy (SEM). Statistical Analysis. Data from the CFU using different cleansing regimes were compared, following log transformation, using one-way analysis of variance (ANOVA). The polished and unpolished tiles were compared for biofilm formation on each cleansing method using an independent t-test. There was no significant difference among the three cleaning methods on the polished or unpolished tiles. However, in polished tiles, streptococci were significantly reduced in all cleaning methods, whereas staphylococci and Staphylococcus aureus were markedly decreased in brushing and combination cleaning methods. However, the total number of anaerobic bacteria was significantly reduced in polished tiles using the combination method only. Polishing the fitting surface of an acrylic-based orthodontic appliance reduced the tested bacterial biofilm formation and may enhance cleaning efficiency. Brushing and combination methods showed superior cleaning effects compared to cleaning tablets. This trial is registered with NCT05707221.

Anticandidal Activity of Cajuput and Lemongrass Essential Oils Supplemented in Alcohol-Free Mouthwash Against Candida albicans Biofilm Formation on 96-Well Plate and Acrylic Surfaces

The present study aimed to evaluate the efficacy of alcohol-free mouthwash containing cajuput and lemongrass essential oils and their synergistic effect on eliminating Candida albicans biofilm formation, the most common causative agent of denture stomatitis. The inhibitory activity against C. albicans ATCC10231 biofilm formation on 96-well plate and acrylic surfaces of this formula was significantly different from 0.12% chlorhexidine solution at 20 minutes (P < 0.0001). At one hour and eight hours of immersion, the activity of this formula was similar to the activity of 0.12% chlorhexidine mouthwash. After treatment with this formula, there were less densely active cells and biofilm compared to the negative control, and the action was close to that of 0.12% chlorhexidine mouthwash. The minimal inhibitory concentrations of cajuput and lemongrass essential oils were 2 and 4 µL/mL (for 0.2% and 0.4% v/v, respectively). For chequerboard assays, the fractional inhibitory concentrations of these oils were 0.5 and 0.25 µL/mL, respectively. The combination of cajuput and lemongrass oils in this formula exhibited partial synergism against C. albicans ATCC10231 biofilm formation with a fractional inhibitory concentration index of 0.75. This study demonstrated the inhibitory activity of this formula against C. albicans biofilm formation on 96-well plate and acrylic surfaces after quantitated by colony enumeration and the XTT reduction assay resembled 0.12% chlorhexidine mouthwash. In conclusion, that C. albicans could be inhibited by the partial synergism of these essential oils in this mouthwash formula. Keywords: Inhibitory activity, Natural essential oils, Candida albicans, Microbial biofilm, Solid surface

In vitro efficacy of synthetic lawsone derivative disinfectant solution on removing dual-species biofilms and effect on acrylic denture surface properties

Candida albicans (C. albicans) and Streptococcus mutans (S. mutans) biofilms involve in denture stomatitis. This study compared compound 1 to 2% chlorhexidine gluconate (CHX), Polident, and distilled water (DW) in biofilms reduction and effect on polymethylmethacrylate acrylic (PMMA) properties. The structure of lawsone (naphthoquinone derivative) was modified by the addition of an alkylnyloxy group to yield compound 1. Dual-species biofilms of C. albicans and S. mutans were developed on PMMA discs. The colony-forming unit count measured the number of residual biofilm cells after exposure to the test agents. PMMA discs were examined for color stability, surface roughness, hardness, and chemical structure after 28 days. At 3 min, compound 1 was less effective than CHX in reducing C. albicans (p = 0.004) and S. mutans (p = 0.034) but more effective than Polident in reducing C. albicans (p = 0.001). At 15 min, no viable cells were detectable for compound 1 and its effectiveness was comparable to CHX (p = 0.365). SEM showed fungal cell surface damages in CHX, compound 1 and Polident groups. Only color change was affected by time (p < 0.001) and type of test agent (p = 0.008), and only CHX reached a clinical perception level. Compound 1 is a promising agent for removing biofilm from the PMMA surface without substantially degrading surface properties.

Antimicrobial effect of phytosphingosine in acrylic resin.

This study evaluated color stability (CS), anti-adherence effect (AAE), and cell viability of microorganisms on acrylic resin (AR) surface, treated associated or not with sodium percarbonate (SP). AR specimens were prepared, and color analysis was performed before and after the treatments and the CS was calculated. For analysis of AAE, the samples were sterilized by radiation in a microwave oven. Then samples were randomly distributed: phosphate-buffered saline (PBS - control), 0.5% sodium hypochlorite (SH), phytosphingosine (PHS), and phytosphingosine + SP (PHS+Na2CO3). The specimens remained in contact with solutions for 30 minutes and were later contaminated by Candida albicans. Aliquots were seeded in Petri dishes with Sabouraud Dextrose agar and incubated at 37°C for 24 hours. After the incubation, the number of colonies was counted. The cell viability of adhered microorganisms on the AR was evaluated and 20 fields were observed under an epifluorescence microscope, and the percentage of adhered viable cells was calculated. Data were compared (One-way ANOVA, Tukey, p<.05). As for CS, PHS+ Na2CO3 (0.4±0.1) resulted in less change than PBS (0.9±0.2), similar to the other groups (SH [1.0±0.3)]; PHS [0.9±0.2)]). There was no difference for all tested solutions regarding the ability to avoid microorganism adherence (p>0.05), but PHS (11.2±4.1) resulted in a smaller area of adhered viable cells, statistically different from SH (18.2±7.6) and PBS (26.4±10.8). It was concluded that PHS resulted in lower adhered viable cells and when associated with Na2CO3, also shows a lower effect on the CS of AR.

Mechanical properties and bonding of maxillofacial silicone elastomer mixed with nano-sized anti-microbials.

The antibacterial efficacy of silicone is improved by impregnating it with antimicrobials such as chlorohexidine and zinc oxide. The purpose of this study was to examine mechanical properties and bonding of maxillofacial silicone elastomer mixed with Zinc Oxide nanoparticles (ZnO-NP), and Chlorohexidine Diacetate Salt (CHX) at three different concentrations (1 %, 3 %, and 5 %). Specimens of a silicone elastomer (M511) were prepared and divided into 7 groups. Group 1 was control of no additive. Groups 2-4 included silicone elastomer mixed with ZnO-NP (surface area = 67m2/g) at 3 different concentrations (by weight %); 1 %, 3 % and 5 %. Groups 5-7 included silicone elastomer mixed with CHX at the same concentrations. Tear and tensile strengths, elongation percentage, modulus of elasticity, and shear bond strength to primed acrylic resin surfaces were evaluated. Data was analyzed with 1-way ANOVA, Bonferroni, and Dunnett's T3 post-hoc tests (P<0.05). There was significant effect of the additives on the tensile strength, elongation percentage, tear strength, and shear bond strength (P<0.05). Shear bond strengths ranged from 0.55 to 0.96MPa. Silicone elastomer mixed with CHX (5 %) resulted in the highest shear bond strength (P<0.05). Non-linear regressions between tensile strength and ZnO and CHX additives were 0.95 and 0.96 respectively. All additives reduced the tensile strength of the silicone. However, CHX at 5 % optimized shear bond strength and thus is proposed in order to fabricate maxillofacial prostheses of sufficient mechanical properties, bonding and antimicrobial activity.

Influence of annealing and etching on physical and wetting properties of acrylic surface

The objective of this research aims to study the surface modification of acrylic for superhydrophobic applications. The acrylics were modified using annealing at 50, 75 and 100 °C for 1 h. To evaluate the effect of etching on the morphology of acrylic substrates, two different acids between tetrahydrofuran (THF) and chloroform with their concentration of 99.8 % v/v were used to etch for 1 min. Then, the annealed acrylics were etched by THF because chloroform has highly hazardous acid and low transparency after etching. The effects of annealing and wet chemical etching on morphology, optical properties and wettability can be characterized using atomic force microscopy, scanning electron microscopy, Vickers hardness tester, UV/Vis spectroscopy and water contact angle measurement. This result exhibits that the hardness of acrylic increases with the increase of annealing temperature. Furthermore, the wet chemical etching has direct affected to the wettability of acrylics due to the increasing of surface roughness.

Novel Denture Cleanser Formulated From Virgin Coconut Oil and The Anionic Emulsifier Against Candida albicans Biofilms Formed on 96-Wells Plate and Acrylic Resin Surfaces

Abstract The objectives of this study were to investigate the inhibitory effect of coconut oil denture-cleansing (CDC) formula against Candida albicans biofilm formed on 96-wells plate and acrylic surfaces at various immersion times and to determine the effects on physical properties of heat-cured acrylic surfaces. A total of twenty-seven CDC formulas were prepared. All CDC formulas were evaluated the stability and anticandidal activity by freeze-defrost cycles and broth microdilution assays, respectively. The formula 22th (F22) containing 0.3 g of anionic emulsifier at a ratio 40:60 of virgin coconut oil to distilled water showed the highest stability and anticandidal activity. The percent inhibition against C. albicans biofilm formed on 96-well plate and acrylic resin surfaces of the F22 after 8 hours of immersion were 86.87 ± 0.65%, and 91.19 ± 1.81%, respectively. However, the F22 had significantly lower inhibitory activity than 0.12% chlorhexidine gluconate (P &lt;0.05). Furthermore, flexural strength of acrylic resin specimens was determined using a 3-point bending test and surface roughness was measured with a profilometer. The flexural strength and the change in surface roughness of F22 were not significant different compared with chlorhexidine and distilled water after 8 hours immersion for 30 days (P &gt;0.05). In conclusions, F22 which containing 0.3 g of anionic emulsifier at the ratio of coconut oil to distilled water at 40:60 exhibited the potent inhibitory activity to Candida albicans biofilms and had no significant effect on the flexural strength and surface roughness of acrylic resins after immersion for 30 days. Keywords: Denture cleanser, Coconut oil, Anionic emulsifier, Biofilm, Candida albicans, Acrylic resins

Upconversion 3D printing enhancement via silver sensitization to enable selective metallization

This work presents the synergistic effect of silver (Ag) ions to enhance the crosslinking of 3D printing photopolymers via near-infrared (NIR) to ultraviolet (UV)/visible light upconversion (UC) and allow selective metallization of multi-material parts. By incorporating a commercial micron-sized ytterbium-thulium co-doped sodium yttrium fluoride phosphor (NaYF4:Yb3+, Tm3+) into a photopolymer resin, a low-cost NIR laser is used to initiate curing exactly at the focal point in the depth of the vat, allowing voxel crosslinking in any point of the space at a depth in the centimeter scale, beyond the traditional layer-by-layer 2D scheme. This allows the printing with the presented resin on pre-existing printed parts, which is the basis for multi-material integration in 3D printing, beyond the 2D limitation. The addition of Ag(I) ions in the photopolymer enables improved photo-curing at 10-fold faster speeds, after printing through 10 mm of resin. In our approach, after the 3D printing process, the Ag(I) ions embedded into the photopolymer serve as seeding sites for electroless copper (Cu) plating, which allows the integration of metalized parts on different substrates, such as glass and 3D printed polymer. Finally, selective copper plating has enabled the manufacture of objects with metal (copper) and plastic (acrylic) surfaces.

A randomized trial of the effectiveness of an ultrasonic denture hygiene intervention program among community dwelling elders.

This study aimed to assess the effectiveness of ultrasonic denture hygiene interventions in improving denture cleanliness among elderly individuals. Sixty-six participants who had received upper metal framework removable partial dentures within the past 5 years were randomly allocated into three denture hygiene intervention groups: group 1 (mechanical cleaning with a toothbrush and ultrasonic cleaning with cetylpyridinium chloride), group 2 (mechanical cleaning with a toothbrush and ultrasonic cleaning with distilled water), and control (mechanical cleaning with a toothbrush only). Denture cleanliness was assessed at baseline and 1-month using: i) Denture Cleanliness Index (DCI) scores; ii) plaque coverage percentage; and (iii) microbiological samples for bacterial and yeast detection. Differences between groups were assessed with one-way analysis of variance and Chi-squared tests. Mean DCI scores and mean percentages of plaque coverage area were significantly reduced in group 1 and group 2, compared to the control group for both cobalt chromium (CoCr) and acrylic fitting surfaces (p<0.001). No significant differences were found between groups 1 and 2 with regard to the prevalence and viable counts of yeasts or total microbial viable counts. No significant differences in the investigated clinical and microbiological parameters were observed between CoCr and acrylic surfaces following the intervention period. The ultrasonic cleaner was significantly more effective than mechanical cleaning in the reduction of biofilm coverage on metal framework removable partial dentures over a 1-month intervention period. Nevertheless, the adjunctive use of cetylpyridinium chloride with ultrasonic cleaning did not yield additional benefits.

Effectiveness of Aspergillus sp. extract in denture adhesive on surface roughness of acrylic resin on Candida albicans biofilm formation

The denture adhesive increases retention on the denture base and affects oral microorganisms. Adding antifungals to denture adhesives can inhibit the Candida albicans biofilms formation and prevent denture stomatitis. The combination of denture adhesives and herbal medicines is an alternative to antifungals, which have few side effects because it is a plant. Moreover, one of them is the endophytic Aspergillus sp. extract containing chemical compounds that can inhibit the Candida albicans biofilms formation. This study aims to analyze the effectiveness of the endophytic Aspergillus sp. extract in denture adhesive materials for Candida albicans biofilm formation on acrylic resin surfaces. The research method is to extract the Aspergillus sp. extract antibiofilm test. Denture adhesive formulation was adjusted to the standard, and added Aspergillus sp. with concentrations of 3.125%, 6.25%, 12%, and 25%. The research sample used hot polymerized acrylic resin. The control group used X denture adhesive and added nystatin, each group suspended by Candida albicans for 24, 48, and 72 hours. Examination of biofilm formation activity on the surface of acrylic resin used SEM. The analysis used Two Way Anova. Aspergillus sp. extract in denture adhesive effectively prevents Candida albicans biofilm formation within 24 hour incubation time. In conclusion, extract of the endophytic Aspergillus sp. in denture adhesive can inhibit the formation of Candida albicans biofilm on the surface roughness of acrylic resin.

Molecular Simulation Strategies for Understanding the Degradation Mechanisms of Acrylic Polymers.

Acrylic polymers, commonly used in paints, can degrade over time by several different chemical and physical mechanisms, depending on structure and exposure conditions. While exposure to UV light and temperature results in irreversible chemical damage, acrylic paint surfaces in museums can also accumulate pollutants, such as volatile organic compounds (VOCs) and moisture, that affect their material properties and stability. In this work, we studied the effects of different degradation mechanisms and agents on properties of acrylic polymers found in artists' acrylic paints for the first time using atomistic molecular dynamics simulations. Through the use of enhanced sampling methods, we investigated how pollutants are absorbed into thin acrylic polymer films from the environment around the glass transition temperature. Our simulations suggest that the absorption of VOCs is favorable (-4 to -7 kJ/mol depending on VOCs), and the pollutants can easily diffuse and be emitted back into the environment slightly above glass transition temperature when the polymer is soft. However, typical environmental fluctuations in temperature (<16 °C) can lead for these acrylic polymers to transition to glassy state, in which case the trapped pollutants act as plasticizers and cause a loss of mechanical stability in the material. This type of degradation results in disruption of polymer morphology, which we investigate through calculation of structural and mechanical properties. In addition, we also investigate the effects of chemical damage, such as backbone bond scission and side-chain cross-linking reactions on polymer properties.

The Use of TRI-Funori® as a Binding Medium for Chromatic Reintegration in Contemporary Unvarnished Paintings

Each material is suited to the different paint material characteristics and pictorial techniques of various artworks by contributing to the pictorial surface’s stability and visual unity, and the ability to display it without interruption. For this article, the polysaccharide TRI-Funori was tested and used as a binding medium for chromatic reintegration in three oil and acrylic mockups of the artwork by Portuguese artist Jorge Martins. This choice was based on characteristics such as compatibility, low toxicity, water-based properties, and good visual properties for color matching. Advantages such as transparency and less tendency to yellow, capacity to dry matte, and ease of removal were observed. It presents good dispersion of inorganic pigments, good visual properties, and good adhesion to oil and acrylic surfaces with or without preparation. However, it also presents disadvantages such as weak dispersion of organic pigments, for example [PB15] Phthalocyanine Blue or [PR83] Carmine Rose, and the tendency to become powdery. During the drying process, it tends to lighten, making the color adjustment process difficult. The mimetic method, achieved with small dots, was used for retouching. The medium was applied with Ferrario® pigmenti puri and Winsor &amp; Newton® powdered pigments, and chromatic reintegration was carried out with a fine brush Winsor &amp; Newton® Finest Sable no1.

Effect of cleaning solutions on surface roughness and flexural strength of removable orthodontic appliances

Purpose: Compare the roughness of self-curing acrylic resin and the flexural strength of nickel-chrome (Ni-Cr) wires of orthodontic appliances submitted to different cleaning processes. Materials and methods: Samples were made with NiCr orthodontic wires bent into a “T” loop and embedded in self-curing acrylic resin and submitted to four different cleaning procedures (n = 21): Group 1 – immersion for 15 minutes in deionized water and active oxygen-based tablet; Group 2 - immersion for 15 minutes in chlorhexidine 0.12%; Group 3 – spray with chlorhexidine 0.12% solution; and Group 4 – immersion in deionized water (control) por 15 minutes twice a day. Flexural strength of the orthodontic wire and roughness of the acrylic resin surface were determined at baseline as well as 90 and 120 days using an optical microscope. Normality of the data was determined using the Shapiro-Wilk test. The Kruskal-Wallis and Mann-Whitney tests were used for comparisons of surface roughness. ANOVA followed by Duncan’s post hoc test was used for the comparison of flexural strength (α = 0.05). Results: No significant difference in surface roughness was found, except in Group 4, in which the last reading (2.25 ± 0.89) was significantly higher than the baseline reading (1.15 ± 0.27) (p = 0.013). Significant reductions in the flexural strength of the wires occurred in all groups (p = 0.002). Conclusions: Immersion in the cleaning solutions did not alter the surface roughness of the acrylic resin but promoted a reduction in the flexural strength of the wires.

Mechanical, thermal and durability performance characterization of novel acrylic solid surface cladding panels in a multidisciplinary test-chain

In line with the international efforts towards a further reduction of energy consumption and global emissions in the construction sector, cladding systems can play a key role thanks to their fundamental contribution to the overall building energy efficiency. In this framework, the paper elaborates on the application of a multidisciplinary approach towards the characterization of novel cladding panels made of an innovative acrylic-based solid surface material. Their performance has been assessed combining different mechanical, thermal and durability tests, showing promising results, for example, in terms of elasticity and resistance to severe environmental conditions, major wind loads or substantial thermal gradients.

Effect of EVA-TiO2 composite interfacial buffer layer in improving the bond strength between PMMA denture base and PDMS liner

Polydimethylsiloxane (PDMS) is the most common dental liner that is used with acrylic dentures. A strong bond between the liner and the denture is a must, for the proper functioning and the longevity of the prosthesis. Debonding of the liner may occur due to an inefficient bond with the denture, or low cohesive strength due to wettablility/hydration and water/liquid storage-retention. The increased wettability/hydration pass on the moisture to the acrylic boundary surface causing initiation of debonding process. Hence, in order to prevent the debonding due to wettablility/hydration a novel method of introducing a hydrophobic polymer interfacial buffer layer between the acrylic denture surface and the PDMS liner surface is suggested. In, the present research work, ethylene vinylacetate (EVA) reinforced with titania (TiO2) polymer microfilm composite layer is prepared by solution casting method. The thin polymer film is placed between the acrylic denture surface and the PDMS liner surface and heat cured together to obtain a hydrophobic interfacial buffer layer. Wettability, fluid absorption and retention tests were performed to investigate the hydrophobic properties of the composite interfacial buffer layer. Mechanical strength properties on the prepared specimen (as per ISO 178) revealed that the EVA-TiO2 layer offered superior bonding and also improved the overall mechanical properties of the acrylic dentures without disturbing the mass and density of the denture.

Action of chitosan-based solutions against a model four-species biofilm formed on cobalt-chromium and acrylic resin surfaces.

To evaluate the anti-biofilm action of chitosan, nanoparticulate chitosan, and denture cleanser Nitradine™ against biofilms comprising Candida albicans, Candida glabrata, Staphylococcus aureus, and Streptococcus mutans. Biofilm removal from removable partial dentures (RPD) is important for success in prosthetic rehabilitation. The anti-biofilm action of the experimental chitosan-based solutions and Nitradine™ was evaluated on acrylic resin and cobalt-chromium alloy through assessing cell viability, cell metabolism, residual aggregated biofilm, and extracellular polymeric substance and biofilm morphology. Only chitosan reduced the viability of C. albicans on cobalt-chromium alloy surface, by 98% (a 1.7 log10 reduction in cfu). Chitosan-based solutions neither promoted substantial alteration of the metabolic activity of the four-species biofilm nor reduced the amount of the aggregated biofilm. After immersion in chitosan and nanoparticulate chitosan, viable microorganisms and extracellular polymeric substances distributed over the entire specimens' surfaces were observed. Nitradine™ reduced the viability and metabolic activity of biofilm grown on both surfaces, but it did not remove all aggregated biofilm and extracellular polymeric substances. After immersion in Nitradine™, approximately 35% of the specimens' surfaces remained covered by aggregated biofilm, mainly composed of dead cells. Although chitosan and Nitradine™ promoted changes in the viability of microorganisms, neither solution completely removed the four-species biofilm from the Co-Cr and acrylic resin surfaces. Thus, isolated use of hygiene solutions is not indicated for biofilm control on RPDs; this requires complementary mechanical removal.

Design of a Magnetic Soft Inchworm Millirobot Based on Pre-Strained Elastomer with Micropillars.

Rather than using longitudinal "muscle" as in biological inchworm, the existing magnetic active elastomer (MAE)-based inchworm robots utilize magnetic torque to pull and push the soft body, which hinders its locomotion mobility. In this paper, a new pre-strained MAE inchworm millirobot with micropillars is proposed. The pre-strained elastomer serves as a pre-load muscle to contract the soft body, and the micropillars act as tiny feet to anchor the body during the locomotion. The proposed magnetic inchworm robot features a simple fabrication process that does not require special magnetization equipment. For the first time, the pre-load muscle is introduced in the design of magnetic inchworm robots, making it more like a real inchworm in terms of locomotion mechanism. The locomotion principle and parametric design for the desired locomotion performance have been investigated. Experimental results show that the fabricated magnetic inchworm robot (size: 10 mm × 5 mm, micropillars length: 200 µm, and mass: 262 g) can locomote on a smooth acrylic surface (roughness of 0.3 µm) at the speed of 0.125 body lengths per second, which is comparable with the existing magnetic inchworm robots. Moreover, the locomotion capabilities of the inchworm robot on wet surfaces and inclined planes have been verified via experimental studies.

PHYSICAL RESPONSE OF ACRYLIC RESIN IN EFFECT OF Ziziphus mauritiana LAM RELATED TO GROWTH AND BIOFILM FORMATION OF Candida albicans

This study evaluated the potential of Ziziphus mauritiana Lam (Z. mauritiana Lam) ethanol extract improves thermal stability and strength to prevent the growth and biofilm formation of C. albicans.The assessment of heat release (thermal equilibrium) of acrylic resin using Differential scanning calorimetry, the strength of acrylic resin with the universal testing machine, growth assessment of C. albicans by spectrophotometry, and biofilm assay with crystal violet and visual images used to a microscope. Z. mauritiana Lam 12.5% provides better thermal stability with a cooling peak enthalpy of -223.27 cal/g. In addition, concentrations of 6.25% and 3.125% at 48 hours had a better ability to increase the strength of acrylic resin (p&gt;0.05). Z. mauritiana Lam at all concentrations and incubation of 24 and 48 hours were similar in decreasing the growth of C. albicans (0.06-0.08 or equivalent to 0.05). The Z. mauritiana Lam increased heat release (thermal stability) in acrylic resin, which caused an increase in transverse strength. At the same time, it reduces the growth and biofilm formation of C. albicans on the acrylic resin surface.