Prismatic Pattern Research Articles

Preventing proximal enamel caries in neighboring tooth with glass ionomer cement restoration and silver diamine fluoride pretreatment

ObjectiveTo investigate caries preventive effects of 38 % silver diamine fluoride (SDF) pretreatment on neighboring tooth proximal to glass ionomer cement (GIC), including conventional GIC (CGIC) and resin-modified GIC (RMGIC) restorations in an in vitro model. Methods: Human tooth blocks were restored withSDF+CGIC (Group 1), CGIC (Group 2), SDF+RMGIC (Group 3) or RMGIC (Group 4). Enamel specimen simulating proximal surface of neighboring tooth was placed in proximity to the restorations. The specimen underwent cariogenic challenge with cross-kingdom biofilm of Streptococcus mutans, Lacticaseibacillus casei and Candida albicans. After cariogenic challenge, the biofilm's growth kinetics, viability, and morphology were evaluated by propidium monoazide-quantitative polymerase chain reaction (PMA-qPCR), confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), respectively. The enamel lesion depth, surface morphology and crystal characteristics were determined by micro-computed tomography (micro-CT), SEM and X-ray diffraction (XRD), respectively. ResultsPMA-qPCR demonstrated lower microbial growth in Group 1 and 3 compared with Group 2 and 4 (p < 0.05). CLSM showed the dead−to-live ratio in Groups 1–4 were 1.15±0.12, 0.53±0.13, 1.10±0.24 and 0.63±0.10, respectively (Group 1,3 > 2,4, p < 0.05). SEM revealed Groups 1 and 3 had scattered biofilm whereas Group 2 and 4 had confluent biofilm. Micro-CT showed the enamel lesion depths (µm) were 98±9, 126±7, 103±6 and 128±7 for Group 1 to 4, respectively (Group 1,3 < 2,4, p < 0.05). SEM revealed oriented and ordered enamel prismatic patterns in Group 1 and 3, not in Group 2 and 4. XRD showed the reflections of hydroxyapatite in Groups 1 and 3 were sharper than Groups 2 and 4. ConclusionSDF pretreatment enhances the preventive effect of GIC on proximal enamel surface on neighboring tooth through inhibiting cariogenic biofilm, reducing enamel demineralization and promoting enamel remineralization. Clinical significanceSDF pretreatment of GIC restorations can help prevent caries on neighboring teeth, particular for patients with high caries risk.

Polymer-encapsulated UV-curable stacked prismatic layers of all-halide phosphor composites for white luminescence

Perovskite halide nanocrystals have been actively investigated for use in white-luminescence photonic devices. Herein, a remote phosphor-layered composite consisting of all-halide red and green nanocrystals embedded in an ultraviolet (UV)-cured matrix is proposed as a facile way to create competitive white luminescence. Alternating stacks of cast halide layers with controlled concentration and thickness yielded true white luminescence characteristics when the halide layers were combined with a bottom blue chip. Specifically, the adjusted prismatic pattern for the red halide layer was found to effectively strengthen the emission of white luminescence. In particular, a phosphor-stacked structure of green and red layers with a 9-μm-pitch prismatic pattern resulted in an enhanced luminous efficacy of ∼54.4 lm W−1, which is higher than those of a non-prismatic layer or a larger pitch pattern. Encapsulating both sides of the halide layers with polydimethylsiloxane (PDMS) maintained very effectively the luminescence of the halide layers over the exposure of 300 h.

Efficacy of the dual-action GA-KR12 peptide for remineralising initial enamel caries: an in vitro study.

To investigate the antibiofilm and remineralising effects of the dual-action peptide GA-KR12 on artificial enamel caries. Enamel blocks with artificial caries were treated with sterilised deionised water as control or GA-KR12. The blocks underwent biochemical cycling with Streptococcus mutans for 3weeks. The architecture, viability, and growth kinetics of the biofilm were determined, respectively, by scanning electron microscopy (SEM), confocal laser scanning microscopy, and quantitative (culture colony-forming units, CFUs). The mineral loss, calcium-to-phosphorus ratio, surface morphology, and crystal characteristics of the enamel surface were determined, respectively, using micro-computed tomography, energy dispersive spectroscopy, SEM, and X-ray diffraction (XRD). SEM showed confluent growth of S. mutans in the control group but not in the GA-KR12-treated group. The dead-to-live ratios of the control and GA-KR12-treated groups were 0.42 ± 0.05 and 0.81 ± 0.08, respectively (p < 0.001). The log CFUs of the control and GA-KR12-treated groups were 8.15 ± 0.32 and 6.70 ± 0.49, respectively (p < 0.001). The mineral losses of the control and GA-KR12-treated groups were 1.39 ± 0.09gcm-3 and 1.19 ± 0.05gcm-3, respectively (p < 0.001). The calcium-to-phosphorus molar ratios of the control and GA-KR12-treated groups were 1.47 ± 0.03 and 1.57 ± 0.02, respectively (p < 0.001). A uniformly remineralised prismatic pattern on enamel blocks was observed in the GA-KR12-treated but not in the control group. The hydroxyapatite in the GA-KR12-treated group was better crystallised than that in the control group. The dual-action peptide GA-KR12 inhibited the growth of S. mutans biofilm and promoted the remineralisation of enamel caries. GA-KR12 potentially is applicable for managing enamel caries.

Modelling of Patterned Cathode-Membrane Interfaces with Random Roughness for PEMFCs

Proton Exchange Membrane fuel cells (PEMFCs) are becoming an increasingly promising piece of power generation technology that can fit into the changing economy as we strive towards a sustainable energy-based future. However, PEMFCs struggle to meet the energy demands of the world, falling short of the capability of other energy sources such as fossil fuels, mainly due to price and energy output compared to the already establish combustion engines. Looking internally into the PEMFC itself, one of the main issues is the limitations of the electrode-membrane interface leading to low ion transfer performance from the catalyst layer to polymer electrolyte membrane. If we can improve the cathode-membrane interface facilitating the oxygen reduction reaction (ORR) rate at the cathode, the rate limiting step, we can increase the overall performance of the fuel cell.It is believed that by increasing the interfacial area of the cathode-membrane interface, such as applying a prismatic pattern to the morphology, we can increase the active surface area for the membrane electrode assembly (MEA). By varying the prism frequency and relative height, the interfacial area can be tuned to improve the overall power performance of PEMFCs.In this work, with a LiveLink connection between Matlab and multiphysics software COMSOL, we model the electrode-membrane interface to investigate its influence on the ion-transfer performance of PEMFCs. By varying the number and size of prism peaks applied to the interface, it is shown that we can influence the fuel cell performance whilst maintaining a constant membrane and catalyst loading. The results showed, at an optimal peak frequency and relative height, an improvement of up to 25% was achieved in the power density.Although research into the prismatic morphology looks promising, there are many other potential options when looking for which morphology could yield the best overall power performance out of a PEMFC. As such, looking not only into prismatic patterning, but also a pyramidal morphology could prove beneficial. We're also looking into how the application of the roughness to the interface, created using a combination of Gaussian and Uniform wave functions, will impact any previous results observed, and allow us to simulate a model that fits better with the real-world findings. Figure 1

Optically Tunable Bifunctional Structures Fabricated by Hybrid Imprint‐Photo Lithography (HIPL)

AbstractOptically tunable bifunctional structures are created by hybrid imprint‐photo lithography (HIPL), which is a combination of photolithography and soft lithography via a structured photomask. Prismatic patterns are formed on a flexible photomask, and the structured photomask is exploited as an imprint mold to create two‐layered microstructures that show a tunable refraction property. Fabricated microstructures, such as the perpendicularly aligned cross‐prismatic island (PAC‐PI), show optically dual functionality that originates from each optical property of the upper and lower layers in two‐layered structures with symmetric light collimation in the vertical and horizontal axes along both directions of the upper and lower prismatic layers, whereas a single conventional prismatic film shows only one‐axis collimation. Moreover, tunability of the light collimation, which can be modulated by varying the area ratio of the upper and lower layers from 80% to 20% using optical simulation, is demonstrated. Such optically tunable bifunction on a single sheet could potentially reduce the number of required optical sheets, such as the liquid crystal display backlight unit (LCD BLU). This new hybrid lithography process could provide a potential pathway to construct highly complex optical components, such as planar waveguide, microlight emitting diode, virtual reality/augmented reality, and holographic display devices.

Simulation of Patterned Cathode Catalyst Layer-Electrolyte Interface, with Gaussian Roughness, for Improved PEMFC Power Performance

Proton Exchange Membrane fuel cells (PEMFCs) are becoming an increasingly promising piece of power generation technology that can fit into the changing economy as we strive towards a sustainable energy based future. However, PEMFCs struggle to meet the energy demands of the world, falling short of the capability of other energy sources such as fossil fuels, mainly due to price and energy output compared to the already establish combustion engines. Looking internally into the PEMFC itself, one of the main issues is the limitations of the electrode-membrane interface leading to low ion transfer performance from the catalyst layer to the polymer electrolyte membrane. If we can improve the cathode-membrane interface facilitating the oxygen reduction reaction (ORR) rate at the cathode, the rate limiting step, we can increase the overall performance of the fuel cell.It is believed that by increasing the interfacial area of the cathode catalyst layer-membrane interface, by applying a prismatic pattern to the morphology, we can thus increase the active surface area for the membrane electrode assembly (MEA). By varying the frequency of prisms, and the relative height of these prisms compared to the fixed total height of the catalyst layer and membrane, the interfacial area can be increased, improving the current density, which would result in an improved overall power performance of the PEMFC.In this work, with a LiveLink connection between Matlab and multiphysics software COMSOL, we model the electrode-membrane interface to investigate the influence of the operating conditions and the morphology of the membrane surface on the ion-transfer performance of PEMFCs. By varying the number and size of prism peaks applied to the interface, it is shown that we can influence the fuel cell performance whilst maintaining a constant membrane and cathode volume as well as the amount of platinum used in the catalyst layer whilst, due to economies of scale, maintaining a similar cost per membrane compared to a flat membrane interface.Previous research has shown that there is a negative impact on power performance when the cathode catalyst layer-electrolyte interface is patterned with a low number of peaks with small relative heights compared to the total height of the electrolyte and catalyst layer. However, at higher frequencies of peaks and relative peak heights, an improvement of up to 25% was achieved in the power performance, and a 21% improvement was seen in the polarization curve.However, this model suggests perfectly smooth interfaces between the electrolyte and the catalyst layer. In reality, there would be a level of roughness to this interface, which would have an impact on the results of the simulated fuel cell performance.This research looks into how the application of the roughness to the interface, created using a combination of Gaussian and Uniform wave functions, will impact any previous results observed, and allow us to simulate a model that fits better with the real world findings.The results obtained here could help determine the appropriate parameters required to validify our experimental work, and provide reference for the future work carried out in this research field. Figure 1

Simple prismatic patterning approach for nearly room-temperature processed planar remote phosphor layers for enhanced white luminescence efficiency

Efforts have been made to enhance light-extraction by controlling phosphor structure for higher efficiency white light-emitting diodes (LEDs). Here, we introduce a technical method for improving luminous efficacy by applying prismatic patterns for a planar remote yellow phosphor structure. The remote phosphor structure is based on a UV-cured prismatic pattern/polyethylene terephthalate (PET)/glass substrate/silicate phosphor layer. The phosphor layer was formed via another UV-curing process of the screen-printed polymer/ phosphor-mixture. As a result, the prismatic layer of the apex angle 90° of each pitch enhanced the luminous efficacy of the remote phosphor-LED by 29% compared with the reference sample when a smaller pitch size was used. As anticipated, it is assumed that the escape probability of the emitted lights from a blue LED chip through the phosphor structure increases by reducing the possibilities of total internal reflection at the top surfaces of the structure.

A Scanning Electron Microscopic Study of Enamel Surfaces of Incipient Caries

The surface changes of natural incipient caries in human teeth were examined by scanning electron microscopy. Numerous small round depressions due to dissolved prism ends are observed. The prism sheaths seem to be preferentially demineralized, followed by demineralization of prism cores. Perikymata are well-pronounced. Focal holes and relatively large dissolution areas can be present. A new prismatic pattern of destruction with an appearance of fish scales is found. Evidence of remineralization of the incipient carious lesions is seen on the surfaces of the lesions. This study disagrees with the concept of an intact enamel surface layer.

Bmp2 deletion causes an amelogenesis imperfecta phenotype via regulating enamel gene expression.

Although Bmp2 is essential for tooth formation, the role of Bmp2 during enamel formation remains unknown in vivo. In this study, the role of Bmp2 in regulation of enamel formation was investigated by the Bmp2 conditional knock out (Bmp2 cKO) mice. Teeth of Bmp2 cKO mice displayed severe and profound phenotypes with asymmetric and misshaped incisors as well as abrasion of incisors and molars. Scanning electron microscopy analysis showed that the enamel layer was hypoplastic and enamel lacked a typical prismatic pattern. Teeth from null mice were much more brittle as tested by shear and compressive moduli. Expression of enamel matrix protein genes, amelogenin, enamelin, and enamel-processing proteases, Mmp-20 and Klk4 was reduced in the Bmp2 cKO teeth as reflected in a reduced enamel formation. Exogenous Bmp2 up-regulated those gene expressions in mouse enamel organ epithelial cells. This result for the first time indicates Bmp2 signaling is essential for proper enamel development and mineralization in vivo.

Polarized backlight unit using a polarization-preserving light-redirecting film for improving luminance gain

We proposed and demonstrated a polarized backlight unit (BLU) configuration with a new light-redirecting film (LRF) to improve the luminance gain and light transmittance in liquid crystal displays. We combined a very low birefringence triacetyl cellulose (TAC) base layer with UV-cured prismatic patterns in a mass-producible process to demonstrate a polarization-preserving LRF. Detailed analyses of the states of polarization (SOP) through the LRF were reported. We also fabricated a 7-in. edge-lit BLU using the new LRF. We found that the light directing capability of the new LRF was equivalent to that of a conventional prism film whose base layer was a poly(ethylene terephthalate) (PET) film, and that the new LRF successfully suppressed random polarization changes of the transmitted light. Utilizing these new advantages, we obtained 68% transmittance through the polarizer over the BLU with the new LRF, which was about 1.3-fold that for the BLU with the conventional prism film (54%). We also obtained 127% luminance gain using the new LRF, which was equivalent to that of the conventional prism film. Here, the luminance gain is referred to as the amount of increase in luminance on the surface normal of the light-guiding plate without any film.

Assesment of artificial caries lesions through scanning electron microscopy and cross-sectional microhardness test

To assess through scanning electron microscopy (SEM) and cross-sectional microhardness (CSMH) test whether the methodology exposed in this experiment can be used to produce artificial active white spot lesions (AAWSLs) on smooth unabraded human dental enamel. Ten human permanent molars were used in this experiment. One section of each tooth was double coated with nail varnish except for a limited central area sized 2.5 mm × 1 mm (2.5 mm 2 ). Each specimen was individually exposed to 10.4 ml of a demineralizing solution at pH 5.0, during 42 days (37°C) without agitation. Samples were sectioned in the center of the AAWSL and one half was analyzed in SEM and the other half was subjected to CSMH. Descriptive statistics was performed to determine mean depth of the lesion. The mean depth of AAWSL was 100 μm (s.d. =12.1) and a white dull rough surface could be detected by the unaided eye. SEM images demonstrated that although some surface areas of the lesion appeared to be relatively intact, erosion was present. A prismatic pattern of dissolution was observed in all samples with an enlargement of the prism sheaths and some samples had also sites of destruction of prism cores. This methodology can be used to induce AAWSLs in human dental enamel but surface erosion has to be taken into account when performing CSMH test.

Phosphate recovery through struvite precipitation by CO2 removal: Effect of magnesium, phosphate and ammonium concentrations

In the present study, the precipitation of struvite (MgNH4PO4·6H2O) using the CO2 degasification technique is investigated. The precipitation of struvite was done from supersaturated solutions in which precipitation was induced by the increase of the solution supersaturation concomitant with the removal of dissolved carbon dioxide. The effect of magnesium, phosphate and ammonium concentrations on the kinetics and the efficiency of struvite precipitation was measured monitoring the respective concentrations in solution. In all cases struvite precipitated exclusively and the solid was characterized by powder XRD and FTIR. The morphology of the precipitated crystals was examined by scanning electronic microscopy and it was found that it exhibited the typical prismatic pattern of the struvite crystals with sizes in the range between 100 and 300μm. The increase of magnesium concentration in the supersaturated solutions, resulted for all phosphate concentration tested, in significantly higher phosphate removal efficiency. Moreover, it is interesting to note that in this case the adhesion of the suspended struvite crystals to the reactor walls was reduced suggesting changes in the particle characteristics. The increase of phosphate concentration in the supersaturated solutions, for the magnesium concentrations tested resulted to the reduction of struvite suppression which reached complete suppression of the precipitate formation. Excess of ammonium in solution was found favour struvite precipitation. Contrary to the results found with increasing the magnesium concentration in solution, higher ammonium concentrations resulted to higher adhesion of the precipitated crystallites to the reactor walls. The results of the present work showed that it is possible to recover phosphorus in the form of struvite from wastewater reducing water pollution and at the same time saving valuable resources.

Toothbrush Abrasion of Surface Softened Enamel Studied with Tapping Mode AFM and AFM Nanoindentation

The aim of the present in vitro study was to investigate the toothbrush abrasion of surface softened enamel using tapping mode atomic force microscopy (TM- AFM) and AFM nanoindentation. TM-AFM investigations showed that the typical prismatic pattern as observed after demineralisation was retained after toothbrushing. The exposure to artificial saliva resulted in the deposition of a ‘sausage-shape’ material with random orientation. Brushing of these samples did not lead to a complete removal of this deposited material. Enamel mineral loss increased with increasing demineralisation time and increased further, although only to a small extent, due to subsequent toothbrushing. Exposure to artificial saliva did not alter the amount of enamel mineral lost due to the brushing treatment. AFM nanoindentation investigations showed that the three different demineralisation treatments caused three statistically different reductions in both surface hardness and reduced elastic modulus values, with the shortest exposure time having the least effect on the nanomechanical properties of the enamel samples. Toothbrushing did result only in a small increase in hardness and reduced elastic modulus. The present study has shown that toothbrushing of surface softened enamel leads to minor changes in the surface morphology and nanomechanical properties. The amount of enamel lost due to toothbrushing was independent of the demineralisation time and was lower compared to the mineral loss caused by the demineralisation treatments. Furthermore, the exposure to artificial saliva offers minimal protective effect to the softened enamel surface against toothbrushing.

Micropatterning on Methylsilsesquioxane– Phenylsilsesquioxane Thick Films by the Sol–Gel Method

Prismatic patterns with a pitch of 30 μm and a slant height of 30 μm were embossed successfully in 70:30 (in mol%) methylsilsesequioxane:phenylsilsesqeioxane (MeSiO3/2–PhSiO3/2) thick films on glass substrates by laminating an organic polymer sheet as a stamper with the patterns against the films. The embossed shape of the prismatic patterns precisely agreed with the negative shape of those of the stamper that was used. The resultant MeSiO3/2–PhSiO3/2 films were transparent, and the refractive index of the films was adjusted to 1.51, to match that of the glass substrate.

A NEW GENUS AND SPECIES OF PHYLLOTINE RODENT FROM BOLIVIA

A new species (Muridae, Sigmodontinae, Phyllotini), belonging to a new genus, is described on the basis of 2 specimens from 1 locality in the mountain forests of southeastern Bolivia. Diagnostic features are posteriorly divergent edges of supraorbital region, large and hypsodont molar teeth with somewhat prismatic pattern, and anterior zygomatic process not projecting as an overhanging point. The diploid chromosome number is 56 and the fundamental number is 76. Other external, cranial, dental, and karyologic characters in the tribe and new taxon are described, illustrated, and discussed. The hypothesized phylogenetic placement of the new genus based on gene-sequence, chromosomal, and morphologic data is presented relative to evolutionary relationships of selected phyllotine taxa.

Temperature effects on rod-like zirconia particles. Morphology, degree of crystallinity and texture

The paper reports data concerning zirconia samples obtained by coupling a first hydrolysis reaction of ZrCl 4 in solution at 100°C with subsequent treatments of the powders at higher temperatures (400–800°C). The products of the reactions are characterized by X-ray diffraction, scanning electron microscopy and N 2 adsorption. The samples appear to be composed, at any temperature, of pure baddelyite with a degree of crystallinity which increases with the temperature of preparation. Morphologically, the products have the shape of prismatic rods of variable dimensions. The rods are the result of sintering of the primary particles produced during the precipitation in solution. The general prismatic pattern of the rods is not affected by the temperature of calcination; conversely, the texture of the rods (i.e. the degree of hydration and aggregation of the primary particles) strongly depends on the temperature of the treatment. The nature of the interactions taking place between water and the solid particles, at different temperatures, is discussed.

Enamel structure and microwear: An experimental study of the response of enamel to shearing force

The anisotropic fracturing and differential wear properties of enamel microstructure represent factors that can obscure the predictive relationship between dental microwear and diet. To assess the impact of enamel structure on microwear, this in vitro experimental study examines the relative contributions to wear of three factors: 1) species differences in microstructure, 2) direction of shearing force relative to enamel prisms and crystallites, and 3) size of abrasive particles. Teeth of Lemur, Ovis, Homo, and Crocodylus, representing, respectively, the structural categories of prismatic patterns 1, 2, and 3 and nonprismatic enamel, were abraded by shearing forces (forces having a component directed parallel to abraded surfaces) and examined by scanning electron microscopy. Striation width increased with particle size for nonprismatic, but not for prismatic, specimens. Direction of shear relative to prism and crystallite orientation had a significant influence on striation width in only some prismatic enamels. The different responses of prismatic and nonprismatic enamels to abrasion reflect the influence of structure, but at the level of organization of crystallites rather than prisms per se. Such interactions explain in part the inability of striation width to discriminate among animals with different dietary habits. Heteroscedasticity and deviations from normality also may confound parametric analyses of microwear variables. Variation in crystallite orientation in prismatic enamels may contribute to optimal dental function through the property of differential wear in functionally distinct regions of teeth.

Light reflection by prismatic sheets

The prismatic pattern on controllers used in large luminaires has strong reflective properties in oblique directions. As an example of its use, a flat prismatic sheet may be used to exclude direct light (and direct radiant heat) from the sun in certain circumstances.

Scanning electron microscopy of the human enamel surface layer of incipient carious lesions.

A scanning electron microscopic (SEM) study of the enamel surface layer of human natural white and brown spot lesions has been conducted in deciduous as well as permanent teeth. No ultrastructural difference was noted between white and brown lesions, and the brown spots were bleached after treatment in sodium hypochlorite. Observations of non-acid-etched surfaces of the carious lesions revealed (1) areas of apparently intact enamel, (2) focal holes, (3) a prismatic pattern of destruction and (4) an irregular type of destruction. SEM observations of non-cavitated incipient caries sections in depth showed enlarged prism sheaths in the intact surface layer which are definite pathways from the enamel surface to the body of the lesion. The concept of an intact enamel surface layer has to be reconsidered.

Plastics in the Lighting Industry

The paper deals with the use of plastics materials based chiefly on polymethylmethacrylate and polystyrene for transparent and translucent lighting enclosures. The development is briefly traced from the first introduction of shaped acrylic sheet for fluorescent reflectors and diffusers to the highly complicated range of light controlling enclosures in production today. The manipulation of acrylic sheet is described comparing the old blowing techniques to the present method of producing modern re-entrant and deep drawn shapings. The introduction of modified polystyrene and its effect on the market due to new manufacturing methods is discussed. Extrusion by ring and profile dies and methods of post-extrusion treatment of both sections and sheet to give prismatic patterns are described, and injection moulding practice is discussed together with the possibilities of the production of large area moulding by this method. Some speculation is made on future plastics developments affecting the lighting industry.