Surface Color Change Research Articles

Wood Surface Changes of Heat-Treated Cunninghamia lanceolate Following Natural Weathering

To quickly clarify the effect of heat treatment on weatherability of Cunninghamia lanceolate (Lamb.) Hook., we investigated the surface degradation under natural exposure. A comparison between heat-treated and untreated samples was taken based on surface color changes and structural decay at each interval. Over four weeks of natural exposure, multiple measurements were carried out. Results show that color change decreased in the order of 220 °C heat-treated > untreated > 190 °C heat-treated. The results also indicate that the wood surface color stability was improved via the proper temperature of thermal modification. Low vacuum scanning electron microscopy (LVSEM) results expressed that thermal modification itself had caused shrinking in the wood surface structure. From the beginning of the weathering process, the heat treatment affected the surface structural stability. After natural exposure, the degree of wood structure decay followed the pattern 220 °C heat-treated > 190 °C heat-treated > untreated. Therefore, when considering the impact on the structure, thermal modification treatment as a protective measure to prevent weathering was not an ideal approach and requires further improvement.

Action of plasma-activated lactic acid on the inactivation of inoculated Salmonella Enteritidis and quality of beef

This study aimed to investigate the effects of plasma-activated lactic acid (PALA) on Salmonella Enteritidis and beef quality. To improve the antibacterial efficiency of plasma-activated water (PAW), plasma-activated lactic acid (PALA) was prepared by treating lactic acid (0.05–0.20%) with a plasma jet for 40 to 100 s with subsequent application to the surfaces of beef slices (50 × 50 mm, approximately 10 g). Slices were analyzed for changes in surface color, pH, lipid oxidation and odor. In addition, secondary structure (β-sheet and random coil) of the beef protein was determined using Fourier transform infrared spectrometer. We showed that the antibacterial activity of PALA was closely related to the reaction of NO 2 − with H 2 O 2 as well as the decomposition of NO 2 − under acidic conditions. UV-treated fresh beef slices were spot-inoculated with Salmonella Enteritidis (5.67 log CFU/g) and then immersed in PALA solutions for 20 s; leading to a reduction ranging from 1.24 to 3.52 log CFU/g. Data indicated that there was no negative effect of PALA on beef quality parameters. This study not only provided a theoretical basis for developing a novel decontaminant but also enabled PALA to find a way for practical application. In China, a high concentration of lactic acid (2.0–2.5%) is a widely used bactericidal agent in the beef industry. However, it has a negative effect on the odor and protein of the product. The meat industry faces challenges in achieving the balance between the antimicrobial effect on meat and the quality of the product. Based on this, plasma-activated water (PAW) is a hopeful alternative decontaminant for microbial inhibition on meat, made by treating water with non-thermal plasma, containing reactive species, ions and charged particles, which is safe and environmentally friendly. This study demonstrated that plasma-activated lactic acid (PALA) was more effective and stable than PAW. The PALA treatment of beef slices not only led to the reduction of Salmonella Enteritidis but maintained beef quality. PALA appears a promising decontaminant for the meat industry. • Antibacterial efficacy of PAW was enhanced by 0.77–4.58 log CFU/mL with addition of lactic acid (0.05–0.20%). • Lactic acid resulted in higher amounts of NO and NO 2 after plasma treatment. • No significant changes in color, pH, lipid oxidation, odor and protein of the beef was detected.

Molybdenum Capping Layer Effect on Electromigration Failure of Plasma Etched Copper Lines

The electromigration failure phenomena of plasma etched copper lines with and without the molybdenum capping layer have been studied. Surface color change was observed during the constant current stress of the copper line. For the uncapped line, the color change is due to the copper surface oxidation from the Joule heating effect. For the capped line, it is probably due to the surface oxidation and copper diffusion to the capping layer. For the wide line, the color change near the broken point was obvious due to the local heating effect. The time dependent temperature change of the line was estimated from the resistance-to-time curve assuming that the heat dissipation to the glass substrate was negligible. The pattern of the surface color during the electromigration of the uncapped or capped copper line is a useful reference for the prediction of the line failure spot and time.

Effect of using microencapsulated ascorbic acid in coatings based on resistant starch chayotextle on the quality of guava fruit

Filmogenic solutions based on chayotextle (Shechium edule Sw.) starch mixed with microcapsules of resistant starch (RS) containing ascorbic acid (AA) were used as coatings for guavas. The viscosity properties of the coatings were affected by the concentration of microcapsules in the filmogenic solution. Fruits were coated by dipping them in filmogenic solutions without microcapsules (control) or in solutions with a concentration of microcapsules of 6.25% or 12.5%. Fruits were stored under controlled conditions (4 °C, 65% relative humidity), and the loss of weight, changes in the respiration rate (RR) and physicochemical parameters were assessed. In general, fruits coated with the control solution and solutions containing 6.25% and 12.5% microcapsules showed significant changes in the content of total soluble solids (TSS), pH, and titratable acidity (TA). Significant decreases in RR, firmness and weight were observed in fruits covered with the 12.5%, 6.25% and control solutions, respectively. Fruits covered with edible coatings showed a decrease in ripening, with lower values for their physicochemical properties and reduced changes in surface color compared with uncoated fruits.

Evaluation of the durability of lignin-reinforced composites based on wheat straw/recycled polypropylene blends

The influence of a lignin additive at different loading levels on the surface properties, mechanical, and thermal performance of recycled polypropylene composites reinforced with wheat straw, before and after accelerated weathering, was studied. Eight groups of samples were exposed to an ultraviolet (UV) accelerated weathering tester for a total of 1200 h. The weathered surface morphology, chemical change, and color change were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and chroma meter analyses, respectively. Furthermore, the mechanical properties and oxidation induction time (OIT) were tested. It was shown that the use of lignin had a positive effect in improving mechanical properties and in reducing OIT values of filled composites due to the enhanced fiber/matrix interface bonding and its functions of anti-oxidation. Less fibers were falling off and shallower cracks occurred on the weathered surface of the lignin reinforced composites. The carbonyl index of wheat straw fibers reinforced recycled polypropylene composites (WSF/RPP) with 5 wt% lignin content showed a notable decrease of 4.9% when compared with the growth rate of the control groups. When the stabilizer was introduced to the blends, the mechanical properties and antioxidant capacity of the composites were improved during weathering.

The effect of chemical treatment on green color preservation and surface characteristics of Neosinocalamus affinis bamboo

Bamboo culms or bamboo plywood possessing a native green surface color are highly valuable for use in interior decoration. However, the green surface color of bamboo can easily become discolored in ambient environments without any protection. In order to maintain the green surface color of Neosinocalamus affinis bamboo, this study used copper sulfate (CuSO4), phosphoric acid (H3PO4), and acetic acid (CH3COOH) solutions as protectors. The changes in surface color and characteristics of the bamboo samples before and after the treatment were evaluated. The results showed that the N. affinis bamboo samples treated with 2% CuSO4 solution at 80 °C for 3 h exhibited an attractive green color, with a* and b* values of -7.61 and 5.13, respectively. The indoor durability test result indicated that bamboo samples treated with CuSO4, CuSO4/H3PO4, and CuSO4/CH3COOH solutions all had excellent color durability. After the treatment, the relative copper content on the bamboo surface slightly increased, while the magnesium content decreased. The chlorophyll structure was changed, and reactions between chlorophyll and copper ions may have occurred. The silicon was almost completely removed, and the surface structure of the treated bamboo changed, resulting in good permeability for the treatment.

Development of Label-Free Colorimetric Assay for MERS-CoV Using Gold Nanoparticles.

Worldwide outbreaks of infectious diseases necessitate the development of rapid and accurate diagnostic methods. Colorimetric assays are a representative tool to simply identify the target molecules in specimens through color changes of an indicator (e.g., nanosized metallic particle, and dye molecules). The detection method is used to confirm the presence of biomarkers visually and measure absorbance of the colored compounds at a specific wavelength. In this study, we propose a colorimetric assay based on an extended form of double-stranded DNA (dsDNA) self-assembly shielded gold nanoparticles (AuNPs) under positive electrolyte (e.g., 0.1 M MgCl2) for detection of Middle East respiratory syndrome coronavirus (MERS-CoV). This platform is able to verify the existence of viral molecules through a localized surface plasmon resonance (LSPR) shift and color changes of AuNPs in the UV–vis wavelength range. We designed a pair of thiol-modified probes at either the 5′ end or 3′ end to organize complementary base pairs with upstream of the E protein gene (upE) and open reading frames (ORF) 1a on MERS-CoV. The dsDNA of the target and probes forms a disulfide-induced long self-assembled complex, which protects AuNPs from salt-induced aggregation and transition of optical properties. This colorimetric assay could discriminate down to 1 pmol/μL of 30 bp MERS-CoV and further be adapted for convenient on-site detection of other infectious diseases, especially in resource-limited settings.

Influence of Staining Solutions on Color Change and Enamel Surface Properties During At-home and In-office Dental Bleaching: An In Situ Study.

The purpose of this in situ study was to evaluate the influence of staining solutions (coffee and cola) on the color change, microhardness, roughness, and micromorphology of the enamel surface during at-home and in-office dental bleaching. One hundred and thirty-five enamel bovine blocks were prepared to perform the evaluations. Fifteen volunteers used an intraoral appliance with nine enamel blocks for 15 days. The enamel blocks were randomly assigned among the different groups according to the three treatments: in-office bleaching with high hydrogen peroxide concentration (Opalescence Boost PF 40%, Ultradent) for 40 minutes in three sessions (first, eighth, and 15th days of treatment), at-home bleaching with low carbamide peroxide concentration (Opalescence PF 10%, Ultradent) for 60 minutes daily for 15 days, and a control group (no bleaching agent applied). The enamel blocks were immersed daily in different staining solutions (coffee or cola) for 30 minutes for 15 days or were not submitted to staining (control) to obtain a factorial scheme (3×3) of the dental bleaching treatment and staining solution (n=15). The microhardness analyses (Knoop), roughness evaluations (Ra), surface micromorphological observations, and color measurements (using the CIELAB system and the VITA Classical scale) were made before and after the bleaching treatments to assess immersion in staining solutions. Mixed model tests showed that there was a decrease in enamel microhardness after exposure to cola compared with coffee and the control group (p<0.0001) for both bleaching techniques. Roughness was higher for the cola groups (p<0.0001), and there was no significant difference between the coffee and the control groups. Generalized linear models showed that when no staining solution was applied, lighter color scores were found for the VITA Classical scale (p<0.0001). Without the staining solutions, there was an increase in luminosity (ΔL) (p=0.0444) for in-office bleaching. Lower values of Δa (p=0.0010) were observed when the staining solutions were not used. The Δb (p=0.3929) did not vary significantly between the bleaching agents, but when cola was applied, the values were significantly higher than for the control (p=0.0293). Higher values of ΔE (p=0.0089) were observed for in-office bleaching without staining solutions, while lower values of ΔE were observed for the in-office associated with coffee immersion. Regardless of whether being submitted to bleaching, the enamel stained with cola showed a decrease in microhardness, an increase in roughness, and changes in the micromorphology. The efficacy of the bleaching agents was greater when no staining solution (cola or coffee) was used, and in-office bleaching showed greater color change than the at-home bleaching technique.

Comparison on the Aging of Woods Exposed to Natural Sunlight and Artificial Xenon Light.

To investigate the relationship between sunlight and artificial light sources on the weathering of wood, three woods, namely, Tectona grandis L.F. (teak), Stereospermum colais (mabberley), and Dicorynia guianensis (basralocus), were tested under natural sunlight for 733 days and artificial xenon light for 180 h, respectively. A comparison between sunlight and artificial xenon light was made based on surface color changes at various intervals. The results showed that the woods suffered from more severe aging in the artificial xenon light exposure than that in the natural sunlight exposure. At the early stage of exposure, very good relationships were found between 70 days under natural sunlight weathering and 60 h under artificial xenon light weathering. Compared with natural sunlight, about a 30 times faster aging process was identified in the artificial xenon light. However, the linear relationship vanished at the later aging stage. It was found that the color change fluctuated in natural sunlight, while it increased steadily in artificial xenon light. The wood species affected the aging of woods. In natural sunlight exposure, the color change decreased in the order of mabberley > teak > basralocus, while in artificial xenon light exposure, color change decreased in the order of mabberley > basralocus > teak due to the easier volatilization of extractives in artificial xenon light than in natural sunlight.

Investigation of Imperfections Formed at the Ultrasonic Welding of Copper Sheets

Abstract Ultrasonic welding is a very useful and simple welding process. It is suitable for establishing a joint between thin sheets and dissimilar metals with short preparation and finish work time [1]. Some welding defects were detected due to less than optimal ultrasonic welding parameters. These defects were ruptures, surface colour change and unacceptable deformations. This article aims to identify these failures and their causes.

Symbiotic endolithic microbes alter host morphology and reduce host vulnerability to high environmental temperatures

AbstractThermal stresses, such as those associated with global warming, have the potential to change the strength and even the direction of interspecific interactions. On rocky shores, bio‐eroding microbial endoliths infect the mussel Mytilus californianus. Infestation by microbial endoliths can weaken the shell and lead to mechanical failure and death, increased vulnerability to predation, mechanical damage, etc. However, endolith infestation is associated with the loss of the dark‐colored periostracum, exposing the underlying light gray prismatic layer of the shell and potentially reducing stressful heat gain during low tide. We explore the consequences of the mussel–endolith relationship on mussel tolerance to high environmental temperature through a series of experimental manipulations and comparative observations. Experimental sterilization of the shell surface reduces the rate of periostracum loss, suggesting that the change in shell surface color is indeed caused by microbes residing on/in the shell. Eroded shells absorbed less solar energy than shells with their periostracum intact, and mussel mimics with infested shells remained cooler on sunny days. Manipulation of shell color in the field resulted in higher mortality in black‐painted mussels relative to gray‐painted or naturally eroded mussels. Furthermore, following exceedingly hot weather, mortality was significantly lower for heavily infested, light‐colored mussels than for lightly infested, dark‐colored mussels. Thus, although shell‐boring microbes have the potential to act as parasites under the majority of conditions experienced by mussels, they may be critical mutualists during periods of intense thermal stress. This context‐dependent symbiosis may allow mussels to occupy higher shore levels than would otherwise be possible, and thus indirectly benefit the hundreds of species which use mussel beds as habitat.

Perubahan Warna Permukaan Resin Komposit Nanohybird Pasca Perendaman Dalam Cuko Pempek

The development of science, technology and patient demands regarding restorative materials that are colored with teeth is currently higher. Dental-colored restoration materials are widely used, one of which is nanohybrid composite resin. The nanohybrid composite resin has a small and fine particle size of 0.04 um. Nanohybrid composite resins have many advantages, but they also have the disadvantage of liquid absorption properties which can cause discoloration. One of the liquids that cause discoloration is cuko pempek. Objective: To find out the surface color changes of nanohybrid composite resin after immersion in cuko pempek. Methods, an experimental laboratory study with a pre and post test only group design study design. Sample 16 pieces of nanohybrid composite resin measuring 10 x 2 mm. The sample was immersed using pempek cuko as much as 5 ml with a temperature of 37oC for 7 days. Color change is measured with a spechtrophotometer (UV-2401 PC). Results, there was a change in the surface color of nanohybrid composite resin soaked with pempek cuko which marked an average increase in dE*ab before immersion (18.5925) and after immersion (23.3169) with a difference of 4.7844. The paired t test results also showed a significant color change that is p = 0,000 (p &lt;0.05). Conclusion, there is a change in the surface color of the post-immersion nanohybrid composite resin in pempek cuko.

Revisiting the fabrication of superhydrophobic aluminum surfaces and their use as soft substrates for droplet manipulation

Superhydrophobic aluminum (Al) surfaces are desired in many applications and have been widely studied, but some fundamental issues in their fabrication are not yet fully understood. In this study, commonly used HCl solution and organic acid/sulfur reagents were employed for clarifying the phenomena in etching and composition modification. An unstable layer was revealed after HCl etching, which was removable with water flushing, and this layer, consisting of scattered AlCl3/Al2O3 particles surrounded by Al2O3 plates with cracks, caused changes in surface appearance from bright to dark. A complete change in surface color corresponded to sufficient etching, and hence, this visible phenomenon could be used to confirm the shortest etching time for achieving desirable superhydrophobicity. Composition modification with dodecanethiol and myristic acid also modified the microstructure through a slight etching mechanism and a synergistic effect was found with the use of their mixture, which led to the finest grains and most abundant carbon chains on the final surfaces. Consequently, the best superhydrophobicity was revealed in static and dynamic experiments with droplets. Finally, using the advantage of flexibility, a superhydrophobic Al sheet was demonstrated to be suitable for subjecting droplets to controlled rolling and coalescence, which could be meaningful for many droplet-related studies.

Effect of different finishing and polishing systems on surface roughness and color changes of resin composites: An in vitro study

Background and objective: Finishing and polishing techniques have great importance on the long-term success and aesthetics of the composite restorations. This study aimed to investigate the effect of three finishing and polishing systems on surface roughness and color changes of four different posterior composites. Materials and Methods: Four different posterior composites, nanohybrid, nano-fill, sonic-activated bulk-fill and microhybrid resin-based composite, and three different finishing and polishing systems, Sof-Lex discs, Astropol® and TOR VM discs were used in the study. The disc specimens (15 disc for each resin composite with total n=60) were 10 mm in diameter and 2 mm in height. Before and after finishing and polishing procedure, surface roughness was measured with a profilometer device and the Ra values were recorded. Color changes was examined using spectrophotometer and (ΔE) values were calculated. Data were tabulated and statistically analyzed using analysis of variance and Tukey’s test at significance level of p 0.05) although all composites showed a smoother surface after finishing and polishing procedures. As regard to color changes (ΔE) statistically significant difference was found between composite groups and finishing and polishing system used (p < 0.05). A direct correlation between Ra and ΔE values was found. Conclusions: 1.surface roughness and color stability of resin composite restorations depend mainly on the material compositions and polishing procedure. 2. The effectiveness of the polishing systems was material dependent. 3. Among the material tested, Nanohybrid presented the smoothest surfaces and the least color changed material. 4. The polishing systems in this study, the best system was the TOR VM discs polishing system with respect to the surface roughness and color changes values. 5. Developments in finishing and polishing systems are important for the creation of ideal restorations and are associated with the increased clinical success of dental practitioners

An in vitro comparative evaluation of commonly consumed catechu and catechu with lime on surface roughness and color stability of the conventional nano-hybrid composite.

Aim:Comparative evaluation of commonly consumed catechu and catechu with lime on surface roughness and color stability of the conventional nano-hybrid composite.Methodology:A total of 50 uniform cylindrical disks of 10-mm diameter and 2-mm thickness prepared from the nano-hybrid composite were used in the study. Each sample was randomly divided into three subgroups of 20 samples each in two experimental groups (catechu, catechu, and lime) and 10 samples in the control group (artificial saliva). The samples were immersed in each agent for 15 days. Surface roughness and color changes measurements were noted at the baseline and 15th day by two-dimensional profilometer and spectrophotometer, respectively.Results:It was found that nano-hybrid composite resin showed more surface roughness and color change when immersed in catechu and catechu with lime as compared to the control group. Intergroup comparison showed statistical significant increase in surface roughness and color change in the catechu group followed by the catechu with the lime group and artificial saliva.Conclusion:Within the limits of the present study, it can be concluded that all experimental specimens showed discoloration. At the end of 15th day, among the groups, catechu showed more surface roughness and color change followed by the catechu and lime and the control group.

Influence of Light-curing Units on Surface Microhardness and Color Change of Composite Resins after Challenge

The aim of this study was to evaluate microhardness and color change (ΔE) of composite resins, light cured with different light emission diodes (LEDs) and submitted to artificial accelerated aging (AAA). Two composite resins with lucirin- TPO photoinitiator were selected: Tetric N-Ceram (Ivoclar Vivadent, A1) and Vit-l-escence (Ultradent, WO).A resin with the only camphorquinone photoinitiat or was chosen as a negative control: Filtek Z350XT (3M ESPE, WD). Disc-shaped specimens were prepared (5 mm diameter; 1.5 mm thick) and photopolymerized with an LED with one wavelength (Radii-Cal, SDI) or multiple wavelengths (Valo, Ultradent), for each composite resin (n = 10). Surface microhardness and color evaluations were performed immediately after specimen preparation and after AAA. Microhardness results were analyzed using Kruskal-Wallis and Mann-Whitney tests for multiple comparisons. To compare the evaluation of microhardness at different times, the Wilcoxon test was used. Mean values of ΔE, ΔL, Δa, and Δb were evaluated using two-way analysis of variance (ANOVA), and Tukey test for multiple comparisons (a = 0.05). Regarding microhardness, a statistically significant difference between the two LEDs was observed for Vit-lescence after AAA. When comparing composite resins that were light-cured with the same device, FiltekZ350XT obtained the greatest microhardness. All groups presented a statistically significant decrease in microhardness from the initial time to the AAA. Regarding ΔE, no statistically significant difference between the two LEDs was observed. When comparing composite resins, FiltekZ350XT showed the highest ΔE values. In general, an LED with multiple wavelengths influenced the microhardness of only one resin containing lucirin-TPO after AAA. The ΔE was more influenced by the composite resin than the LED device. The knowledge of composite resin with deficiencies in the polymerization mechanism could contribute to preventing restorations to become more susceptible to color change and reduction of the mechanical strength.

Dyeing of Poplar Wood through High-Pressure Processing: Performance Evaluation

Abstract. Dyeing of poplar wood through high-pressure (HP) processing was evaluated at different pressure levels (40 to 130 MPa) and compared with conventional hot dip treatment. Dyeing performance was evaluated based on external surface color, fractal color dimension, dye uptake, internal color, elemental composition, and subsequent ultraviolet aging of the wood. The internal microstructure of the treated wood was also examined by scanning electron microscopy (SEM). Results showed that the external surface color difference and change in brightness were significantly greater with HP treatment than with hot dip treatment. The hue angle of HP treated wood surfaces was 1.27 to 4.01 higher and the fractal color dimension was significantly (p &amp;lt; 0.05) lower than that of hot dip treated wood, demonstrating more intense and more uniform distribution of color with HP treatment. The internal color of HP treated wood was also more evenly distributed and more intense, while the hot dip treated wood had no internal dye uptake (zero penetration). SEM analysis showed that the wood structure was damaged by HP treatment, which allowed the dye solution to penetrate into the wood more easily. Among the different pressure levels, the higher pressures resulted in better dyeing performance; however, considering the treatment cost, time, and energy efficiency, 100 MPa treatment may be more economical. Keywords: Color, Dyeing, Fractal dimension, High pressure, Hot dip, Poplar wood.

Influence of polishing systems on roughness and color change of two dental ceramics.

PURPOSETo evaluate the polishing effect on roughness and color change of pressed and layering ceramics after immersion in coffee solution.MATERIALS AND METHODS88 ceramic discs (1.0 mm × 10.0 mm) were manufactured - 44 nano-fluorapatite layering ceramics (IPS e.max Ceram. Group C) and 44 pressed lithium disilicate ceramic discs (IPS e. max Press - Group P). Each group was divided into 4 subgroups according to surface treatments: (G) Glaze, (S) Shofu polishing system (Shofu Inc.), (E) Edenta AG polishing System, (KG) 30-µm diamond granulation tip. Surface roughness (Ra) and color change (ΔE) measurings after the surface treatments were performed, before and 12 days after the immersion in coffee solution. A samples' qualitative analysis was conducted with a scanning electron microscopy (SEM). Data were statistically-treated with one-way-ANOVA and Duncan's tests, apart from paired t-test and Pearson's correlation test (α=5%).RESULTSThe decrescent order, both for surface roughness (Ra) and ΔE for both ceramics were: KG > E > S > G (P<.05). With exception for PG and CG subgroups, which did not present statistical difference between them, all other pressed ceramics subgroups presented smaller Ra values and greater ΔE values than the layering ceramics subgroups (P<.05).CONCLUSIONAlthough mechanical polishing systems presented intermediate Ra values, their colors were considered clinically acceptable. There is a strong correlation between the surface roughness and the color change of tested ceramics.

Evaluation of colour change and surface roughness of two resin-based composites when exposed to beverages commonly used by children: an in-vitro study

AimTo evaluate and compare the surface roughness and colour change of microhybrid and nanocomposite after exposure to beverages commonly used by children.MethodsThirty discs were prepared using Filtek Z250 and Filtek Supreme composites. Discs were immersed in distilled water, orange juice and Coca-Cola. Colour and surface roughness were measured at baseline and on days 15 and 30.ResultsFiltek Z250 and Filtek Supreme showed no significant difference in surface roughness and colour change at all measurement times. Immersion solution had a significant effect on surface roughness as well as colour change. Specimens immersed in Coca-Cola demonstrated the highest effect, followed by those immersed in orange juice, while specimens immersed in distilled water had the least effect. There was a significant increase in surface roughness and colour change over time. The change in colour was more evident in the period between baseline measurements and after 15 days. There was a significant interaction between media type and time.ConclusionsBoth composites showed no significant difference in roughness and colour change at all measurement times. There was a significant increase in surface roughness and colour change in all immersion solutions tested over time. Coca-Cola caused unacceptable colour change.

A rapid screening color test for glyphosate using dabsyl derivatization

Glyphosate is the most common herbicide in the world, and involved in many poisoning cases. However, the analysis of glyphosate has been difficult because of its high polarity and zwitterionic structure, and no simple screening tests for glyphosate have been known. The purpose of this study was to develop a rapid screening test for glyphosate. Glyphosate was visualized through a color change induced by dabsyl derivatization, and the derivatized glyphosate was trapped on the surface of zirconia-coated silica particles by specific chemical interaction between a phosphonate group of glyphosate and the zirconia surface. The presence of glyphosate was indicated by the color change of zirconia surface, which was easily noticed by the naked eye. The developed method was applied to biological samples (urine and serum), beverage samples (green tea and cola drink), and soil samples. No false positive was observed and the detection limit was 100 μg/mL for the biological samples and 800 μg/mL for the beverage samples. A simple screening method for glyphosate based on a color test was established. The method is rapid and requires less than 30 μL of samples. The sensitivity was sufficient for most cases of moderate to severe poisoning.