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Aim: While conventional whitening agents provide effective color change, concerns linger regarding enamel health. This study explored the potential of natural alternatives for coffee stain removal on extracted teeth, aiming to identify safe and efficacious options for patients seeking noninvasive bleaching solutions. Materials and Methods: This study employed 50 extracted permanent anterior teeth divided into five groups (negative control, positive control, strawberry, pineapple, and honey). Standardized coffee staining was applied to all teeth followed by 3 weeks of twice-daily treatment with their respective solutions. Shade changes were measured objectively using a Konica Minolta Spectrophotometer CM-5 at baseline and after 1, 7, 14, and 21 days post-treatment. Statistical analysis was conducted with Kruskal-Wallis and Tukey post hoc tests (IBM® SPSS®). Results: Strawberry juice exhibited equivalent ΔE (color change) compared with 35% hydrogen peroxide (P > 0.99), indicating similar stain removal efficacy. Both pineapple juice and honey solution displayed significantly lower ΔE values compared with the control and strawberry juice groups (P = 0.002 and <0.001, respectively), suggesting limited bleaching capability. Conclusion: This study demonstrates the potential of strawberry juice as a viable alternative to conventional bleaching agents, offering comparable stain removal efficacy on coffee-stained teeth and further highlighting the need for further research on their effectiveness in clinical settings. Meanwhile, pineapple juice and honey solution exhibited limited bleaching potential. These findings contribute to the expansion of safe and potentially noninvasive teeth-whitening options. [ABSTRACT FROM AUTHOR]

When droplets of nanoparticle suspension evaporate from surfaces, they leave behind a deposit of nanoparticles. The mechanism of evaporation-induced pattern formation in the deposit is studied by molecular dynamics simulations for sessile nanodroplets. The influence of the interaction between nanoparticles and liquid molecules and the influence of the evaporation rate on the final deposition pattern are addressed. When the nanoparticle-liquid interaction is weaker than the liquid-liquid interaction, an interaction-driven or evaporation-induced layer of nanoparticles appears at the liquid-vapor interface and eventually collapses onto the solid surface to form a uniform deposit independently of the evaporation rate. When the nanoparticle-liquid and liquid-liquid interactions are comparable, the nanoparticles are dispersed inside the droplet and evaporation takes place with the contact line pinned at a surface defect. In such a case, a pattern with an approximate ring-like shape is found with fast evaporation, while a more uniform distribution is observed with slower evaporation. When the liquidnanoparticle interaction is stronger than the liquid-liquid interaction, evaporation always occurs with receding contact line. The final deposition pattern changes from volcano-like to pancake-like with decreasing evaporation rate. These findings might help to design nanoscale structures like nanopatterns or nanowires on surface through controlled solvent evaporation. [ABSTRACT FROM AUTHOR]

Aim: To compare the color stability of two bulkfill (ormocer based or not), two flowable (high and low viscosity) and a universal nanohybrid composite resin after curing and when aged in different staining solutions. Material and Methods: Three hundred twenty discs were made from a low-flowable nanohybrid composite (GrandioSO Heavy Flow), a flowable nanohybrid composite (Grandio Flow), a bulkfill composite (GrandioSO x-tra), an ormocer-based bulkfill composite (Admira Fusion X-tra) and a universal nanohybrid composite (Grandio SO) (n=64). Specimens were subdivided into 4 subgroups, which were immersed in one of the following solutions for 3 hours a day for 30 days: distilled water, filter coffee, red wine and coke (n=16). Color evaluations were done using a dental spectrophotometer at three evaluation stages: immediately before curing, 24 hours after curing and 30 days of staining. Results: After curing; the universal nanohybrid and bulkfill composite showed significantly greater ΔE values than other type composite resins (p<0.05). Bulkfill composite was the most stained resin type in all of the staining solution subgroups (p<0.05). The bulkfill composite followed by universal and flowable nanohybrid composite and the ormocer based bulkfill composite showed the lowest ΔE values after coffee staining (p<0.05). When effects of staining solutions are evaluated; coffee presented the highest staining effect, red wine was the second and, coke and water was the least stained solutions in application to all type of composite resins (p<0.05). Conclusions: According to this study, it can be concluded that bulkfill composites showed the least resistance to staining and the ormocers were successful in color stability. In all tested materials, color changes after curing and after coffee staining were clinically perceptible. Therefore, when choosing a particular shade, such possible color changes should be taken into consideration. [ABSTRACT FROM AUTHOR]

Perhaps the most important reason to understand the deep history of a field is that it is the right thing to do. [ABSTRACT FROM AUTHOR]

We have investigated the formation of central spot when coffee-water-mixture droplets are dried, which is a reverse effect of the famous coffee-ring effect (CRE). Typically, the central spot is unnoticeable or ignored even though it is significant. The ring-shaped stain is due to the capillary flow (CF). The CF is caused by the difference in the evaporation rates between the edge and the center of the droplet owing to a temperature gradient. The same temperature gradient, however, causes the so-called Marangoni flow (MF). The MF is routinely ignored, particularly when the solvent is water. However, from experiments, we found that, in addition to the ring-shaped stain formed by the CRE, central spot is formed. When the volume of a droplet of coffee-water mixture is ∼ 15 μL, the strongest central spot is formed We employed an improved enhanced heat-transfer model, in which the shape of the droplet was assumed to be spheroidal, to understand the effects of the MF on the central-spot formation. According to the model, the formation of central spot can be explained, at least, semi-quantitatively. As a result of the existence of a stagnation point, the direction of flow is changed. Furthermore, the dependence of its location on the initial geometrical parameters of the droplet is very important. In addition, the effect of gravity was investigated for pendant droplets. The central-spot formation is more prominent in pendant droplets than in sessile droplets because the gravity enhances the MF in the pendant droplets, while it hinders the MF in the sessile droplets. [ABSTRACT FROM AUTHOR]

Formation of coffee stain deposits under evaporation of droplets containing aqueous solution of salts placed on silicone-oil impregnated porous substrates was observed. The formation of ring-like deposits was registered for various molar concentrations of salts for the droplets of 5–300 μl in volume. The effect occurred when the contact line was de-pinned, and the evaporation from the edge of a droplet was stopped by the silicone oil. The formation of the coffee stain deposit is related to the soluto-capillary Marangoni flow; the influence of the thermo-capillary flow taking place in parallel is negligible. [ABSTRACT FROM AUTHOR]

This study evaluates the inactivation of Bacillus licheniformis in liquid coffee extract using heating microwaves. To achieve accurate measurements of temperatures, an optical fiber sensor was developed and calibrated for real-time and in situ measurements of the extract. Using a central composite design, the effects of the processing time, power levels and sample volume were evaluated together with the concentration of the soluble solids of the liquid coffee extract and the position of the sample in the microwave cavity. In addition, the physicochemical and sensory properties of the product were evaluated. The results indicate that the greatest reduction of the microorganism occurred when the processing time was 19 seconds at a power level of 6 using a sample volume of 11 mL and that the highest biological destruction occurs when the sample is placed in the center of the microwave cavity. [ABSTRACT FROM AUTHOR]

Objective:This study evaluated the effect of food-simulating media associated with brushing and coffee staining on color stability of different composite resins. Materials and methods:Eighty specimens were prepared for each composite: Grandio SO (Voco), Amaris (Voco), Filtek Z350XT (3M/ESPE), Filtek P90 (3M/ESPE). They were divided into four groups according to food-simulating media for 7 days: artificial saliva (control), heptane, citric acid and ethanol. The composite surface was submitted to 10,950 brushing cycles (200 g load) in an automatic toothbrushing machine. The specimens were darkened with coffee solution at 37 °C for 24 h. After each treatment, color measurements were assessed by spectrophotometry, using CIE L a b system. The overall color change (ΔE) was determined for each specimen at baseline (C1) and after the treatments (food-simulating media immersion/C2, brushing/C3 and dye solution/C4). Data were analyzed by two-way repeated measures ANOVA and Tukey’s tests (p < .05). Results:The results of RM-ANOVA showed significant differences for composites (p = .001), time (p = .001) and chemical degradation (p = .002). The mean of ΔEfor composites were: Z350XT (5.39)a, Amaris (3.89)b, Grandio (3.75)bc, P90 (3.36)c. According to food-simulating media: heptane (4.41)a, citric acid (4.24)a, ethanol (4.02)ab, artificial saliva (3.76)b. For the treatments: dye solution (4.53)a, brushing (4.26)a, after food-simulating media (3.52)b. Conclusions:The composite resin Filtek Z350XT showed significantly higher staining than all other composite resin tested. The immersion in heptane and citric acid produced the highest color alteration than other food-simulating media. The exposure of samples to brushing protocols and darkening in coffee solution resulted in significant color alteration of the composite resins. [ABSTRACT FROM AUTHOR]

Over the past few decades, many food niches have emerged with a specific focus on quality. In specialty coffee, micro roasters have brought about Direct Trade coffee as a way of organising an alternative around new tastes and qualities through ongoing and ‘direct’ relations to farmers and cooperatives. But Direct Trade also involves exporters. We ask, how do exporters and roasters work together in these new coffee relations, and what do they work on? We observe and participate in a situation where Colombian coffee exporters visit Danish roasters. They tour the roasting facilities and taste a number of coffees. Often, the term power is used to analyse such value chain interactions, but we argue that the term coordination better opens up these interactions for exploration and analysis. What emerges is a coordination of quality. Through touring and tasting, issues emerge and differences are laid out. We learn that quality is a continuous achievement. There is friction between the ways in which the roasters and exporters do quality, but these are not done away with through power. They are made known and discussable through the work of coordination. The activity of tasting quality is a coordination device that allows for bringing out differences in how quality is done in practice. Coffee, in this event, is not a fixed object, but shifts as issues of quality are brought up in tasting. This suggests a decentering of the object on the issue of quality. [ABSTRACT FROM AUTHOR]

This study analyzed the overall adsorption rate of metronidazole, dimetridazole, and diatrizoate on activated carbons prepared from coffee residues and almond shells. It was also elucidated whether the overall adsorption rate was controlled by reaction on the adsorbent surface or by intraparticle diffusion. Experimental data of the pollutant concentration decay curves as a function of contact time were interpreted by kinetics (first- and second-order) and diffusion models, considering external mass transfer, surface and/or pore volume diffusion, and adsorption on an active site. The experimental data were better interpreted by a first-order than second-order kinetic model, and the first-order adsorption rate constant varied linearly with respect to the surface area and total pore volume of the adsorbents. According to the diffusion model, the overall adsorption rate is governed by intraparticle diffusion, and surface diffusion is the main mechanism controlling the intraparticle diffusion, representing >90% of total intraparticle diffusion. [ABSTRACT FROM AUTHOR]

Influence of laser ablation conditions on limit of detection, spatial resolution and time of analysis was studied for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) applied to elemental mapping. Laser repetition rate and laser fluence were investigated in tapeworm thin section to attain optimum ablation rate, yielding appropriately low detection limit which complies with elemental contents in the tissue. Effect of combinations of laser spot size and scan speed on relative broadening (Δ w rel ) of image of the ablated pattern (line) was investigated with the aim to quantify the trueness of imaging. Ink lines printed on paper were employed for the study of influence of spot size and scan speed on limit of detection, relative broadening of elemental image and duration of elemental mapping. An uneven distribution of copper in a printed line (coffee stain effect) was observed. The Δ w rel is strongly reduced (down to 2%) at low scan speed (10 μm s −1 ) and laser spot diameter of 10 μm but resulting in unacceptably long time of mapping (up to 3000 min). Finally, tapeworm thin-section elemental maps (4 mm × 5 mm) were obtained at the laser spot diameter of 65 μm and the scan speed of 65 μm s −1 within 100 min. A dissimilar lateral distribution of Pb was observed in comparison with that of Cu or Zn due to different pathways of element uptake. [ABSTRACT FROM AUTHOR]

In this study we investigated the underlying mechanisms of coffee stain formation on paper – a porous substrate. When a drop of aqueous liquid containing dispersed materials dries on paper, the faster water evaporation rate at the edge of the drop drives the redistribution of the dispersed materials to the edge of the drop-covered area on paper. Deegan׳s discovery has been accepted as the “coffee ring” phenomenon, which has wide implications. However, stains left by dried aqueous liquids on paper are not always ring-shaped. This is because, besides Deegan׳s coffee ring effect, the transport of dispersed materials in porous media is affected by chromatographic and filtration effects, which are highly dependent upon the properties of the substrates. In this work we clarify the influences of different mechanisms to the dispersed materials redistribution in paper. [ABSTRACT FROM AUTHOR]

Cafestol (caf) and kahweol (kah) are two diterpenes uniquely associated with the unsaponified lipid fraction of coffee brew and are reported to be responsible for an increase in serum cholesterol and triglyceride levels. The plant growth regulators (PGRs) indole-3-acetic acid (IAA), N-benzyladenine (BA), and thidiazuron (TDZ); the plant growth-promoting agents silver nitrate, triacontanol (TRIA), and coconut water; and some PGR antagonists such as lovastatin, paclobutrazol, and 2,3,5-triiodobenzoic acid (TIBA) were used to determine the variation of caf and kah in somatic embryos of Robusta coffee ( Coffea canephora, CxR variety). Embryogenic (EG) medium was comprised of half-strength Murashige and Skoog basal components (½MS) supplemented with 2.85 μM IAA and 1.11 μM BA. After an 8-wk culture, somatic embryos were subjected to diterpene extraction and HPLC analysis of caf and kah profiles. TRIA-supplemented (5 μg L) EG medium devoid of IAA reduced the levels of caf and kah by 18-24 and 48-55%, respectively, in coffee somatic embryos. Similarly, the combination of 2.85 μM IAA, 2.27 μM TDZ, and 5-10% coconut water in ½MS basal medium drastically reduced the caf and kah levels in somatic embryos. There was 60-75% reduction in both caf and kah in the presence of 5 μM TIBA, followed by 56-62% reduction in the presence of 10 μM silver nitrate. In contrast, there was 25-32% elevation of caf and kah in EG medium supplemented with 5 μM paclobutrazol. In this study, for the first time, somaclonal variants of C. canephora with reduced levels of diterpenes caf and kah were established. Furthermore, these lines exhibited consistency in their metabolite profiles when cultivated under greenhouse conditions. In-depth investigations at physiological level are warranted in order to elucidate the actual mechanism of these PGR inhibitors on alterations in endogenous pools of diterpenes in coffee somatic embryos. [ABSTRACT FROM AUTHOR]

In the current paper, we preparedmicrostructured porous filmsby the breath figures approach using polymer blends consisting ofpolystyrene as the major component and an amphiphilic additive, eithera synthetic block copolymer {two different polystyrene-b-poly[poly(ethylene glycol) methyl ether methacrylate] copolymers}or a series of commercial surfactants. Tetrahydrofuran was employedas the solvent. Confocal micro-Raman spectroscopy demonstrated thepreferential location of the amphiphilic additives in the cavitiesof the film as a consequence of the breath figures mechanism. However,the distribution of the copolymer within the cavities varies dependingupon the structure and, more precisely, the surface properties ofthe additives, leading to three different situations. First of all,the copolymer with a larger polystyrene segment, insoluble in thecondensed water droplets, is homogeneously distributed along the wholesurface of the cavities. On the contrary, when the copolymer is solublein water (shorter polystyrene segment), it migrates inside the dropletand a coffee-stain phenomenon takes place during the water dropletevaporation, conducting to a ring-like deposition on the top edgeof the cavities. Finally, when a water-soluble surfactant with highsurface activity is used, the surfactant is solubilized inside thewater droplets, which provokes a decrease on the surface tension andthe coffee-ring effect is modified. In this situation, the copolymercovers the bottom of the pore. [ABSTRACT FROM AUTHOR]

Abstract: Inkjet printing of structures like microscopic electronic circuit paths on thin substrates includes drop wise application and drying of particulate suspensions. The drying of these drops can leave behind a multiplicity of structures of sediment deposit, which to control is a major subject of investigation in the design of the process. In this work we present a simple and efficient simulation method for predicting the three dimensional structure of sediment deposits based on a one way coupled scheme of Brownian dynamics and analytic modeling of the fluid flow inside a drying colloidal drop under presence of Marangoni flow. Aiming for micrometer sized drops with high particle concentrations (up to 20vol.%), our method takes into account particle diffusion and convection, particle collisions as well as particle staggering at the contact line. The method is validated by experimental results and applied to predict the behavior of a new setup. We find from our simulations that DLVO forces may be neglected for a well stabilized suspension and that the model works well in predicting coffee stain formation. [Copyright &y& Elsevier]

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Droplets are of great scientific interest because studying their formation and dynamics is important in many technologies such as in microfluidics [1, 2]. Evaporation of droplets is another interesting aspect that has caught much scientific attention. An example of an evaporating droplet is a coffee droplet spilled on a table. After evaporation the coffee droplet leaves a ring-like stain called a coffee ring or coffee stain [3]. This phenomenon, known as the 'coffee ring effect', occurs not only with coffee droplets but also with all droplets containing non-volatile solutes. There are a number of interesting physical processes going on within the droplets during evaporation to form the 'coffee stains'. In this article, we will see what they are. [ABSTRACT FROM AUTHOR]

A review of the article discussing use of surfactants to control the coffee-ring effect, published in the periodical "Angewandte Chemie International Edition" in 2014 is presented.

The article discusses the ring-shaped stain formed after spilled coffee has dried which represents a complex engineering problem involving principles of heat and mass transport, fluid mechanics, and surface phenomena. It references the article "Transport and Deposition Patterns in Drying Sessile Droplets" by Ronald Larson in an issue of the American Institute of Chemical Engineers Journal." It offers an understanding of processes by which a liquid drop on a surface evaporates and forms a stain.