Characterization of lodging variation of weedy rice.

Weedy rice (Oryza spp.), one of the most notorious weeds of cultivated rice, evades eradication through stem lodging and seed shattering. Many studies have focused on seed shattering, whereas variations in lodging have received less attention and the underlying mechanisms that cause the differences in lodging between weedy and cultivated rice have not been studied in detail. Here, we compared lodging variation among diverse Chinese weedy rice strains and between weedy rice and co-occurring cultivated rice. The chemical composition of basal stems was determined, and transcriptome and methylome sequencing were used to assess the variation in expression of lodging-related genes. The results showed that the degree of lodging varied between indica-derived weed strains with high lodging levels, which occurred predominantly in southern China, and japonica-derived strains with lower lodging levels, which were found primarily in the north. The more lodging-prone indica weedy rice had a smaller bending stress and lower lignin content than non-lodging accessions. In comparison to co-occurring cultivated rice, there was a lower ratio of cellulose to lignin content in the lodging-prone weedy rice. Variation in DNA methylation of lignin synthesis-related OsSWN1, OsMYBX9, OsPAL1, and Os4CL3 mediated the differences in their expression levels and affected the ratio of cellulose to lignin content. Taken together, our results show that DNA methylation in lignin-related genes regulates variations in stem strength and lodging in weedy rice, and between weed strains and co-occurring cultivated rice.

Supramolecular Strategy Based on Conjugated Polymers for Discrimination of Virus and Pathogens.

A conjugated polymer-based supramolecular system is designed for discrimination of virus and microbes. The supramolecular system is composed of cationic polythiophene derivative (PT) and barrel-shaped macrocyclic molecular cucurbit[7]uril (CB[7]). Because PT and PT/CB[7] complexes possess different interaction manners toward virus and microbes, the rapid and simple discrimination of virus and microbes was realized through polymer fluorescence intensity change assisting with standard linear discriminant analysis (LDA). The supramolecular strategy would expand the idea of designing biological probes and further promote the extensive application of conjugated polymer materials in biosensor field.

Cationic Conjugated Polymers-Induced Quorum Sensing of Bacteria Cells.

Bacteria quorum sensing (QS) has attracted significant interest for understanding cell-cell communication and regulating biological functions. In this work, we demonstrate that water-soluble cationic conjugated polymers (PFP-G2) can interact with bacteria to form aggregates through electrostatic interactions. With bacteria coated in the aggregate, PFP-G2 can induce the bacteria QS system and prolong the time duration of QS signal molecules (autoinducer-2 (AI-2)) production. The prolonged AI-2 can bind with specific protein and continuously regulate downstream gene expression. Consequently, the bacteria show a higher survival rate against antibiotics, resulting in decreased antimicrobial susceptibility. Also, AI-2 induced by PFP-G2 can stimulate 55.54 ± 12.03% more biofilm in E. coli. This method can be used to understand cell-cell communication and regulate biological functions, such as the production of signaling molecules, antibiotics, other microbial metabolites, and even virulence.

[Interaction between latex microspheres and antibody proteins revealed by fluorescence spectroscopy].

Latex-antibody complexes were prepared by the method of covalent coupling and the properties of the complexes were studied by fluorescence spectrophotometric method for the purpose of revealing the interaction between latex microspheres and antibody proteins. Analysis of intrinsic fluorescence spectra showed that after being coupled with latex microspheres, the emission maximum of antibody protein showed an obvious blue shift, the intensity of emission maximum decreased significantly, the tertiary structure of antibody protein changed to some extent, the interaction between latex microspheres and antibody proteins had a great quenching effect on the intrinsic fluorescence spectra of antibody proteins, the quenching effect was enhanced along with the increasing pH value and latex concentration, and the quenching mechanism was static quenching. Results of exogenous fluorescence spectra showed that the fluorescence intensity of emission maximum was enhanced significantly after being coupled with latex microspheres, the hydrophobicity of antibody protein was decreasing with the increase in the pH values, however, due to the increasing latex concentration, the hydrophobicity antibody protein was increasing.

Molecularly Imprinted Electrochemical Sensor Based on Nitrogen-doped Molybdenum Carbide Nanosphere for Trace Analysis of Resveratrol.

A novel molecularly imprinted electrochemical sensor based on nitrogen-doped molybdenum carbide(N-Mo2 C) nanosphere was fabricated for trace analysis of resveratrol in this work. N-Mo2 C with large specific surface area and good electrical conductivity was introduced to construct a sensitive imprinting platform. Molecularly imprinted polymer film was prepared through a simple electropolymerization method using resveratrol as the template molecule and o-phenylenediamine as the functional monomer. The sensor shows great analytical performance in the concentration range of 10-9  mol L-1 to 10-4  mol L-1 and the detection limit is as low as 4.37×10-10  mol L-1 . The sensor also has the advantages of good selectivity, reproducibility and stability, which opens a new way for the application of molecularly imprinted electrochemical sensors in the field ofbiomedicine detection.

3D Bioprinting of Reinforced Vessels by Dual-Cross-linked Biocompatible Hydrogels.

3D bioprinting offers a powerful tool to fabricate vessel channels in tissue engineering applications, but inadequate strength of the vascular walls limited the development of this strategy and reinforced channels were highly desired for vascular constructions. Herein, we demonstrated a dual cross-linking system for 3D bioprinting of tubular structures, achieved by a combination of photo-cross-linking and enzymatic cross-linking. Photo-cross-linking of gelatin methacryloyl (GelMA) was achieved with a photoactive conjugated polymer PBF under 550 nm irradiation. Enzymatic cross-linking utilized cascade reactions catalyzed by glucose peroxidase and horseradish peroxidase that can cross-link both methacrylate and tyrosine moieties of GelMA. After removing the 3D-printed sacrificial layer (Pluronic F-127), the obtained perfusable channels showed great biocompatibility that allowed endothelial cells to adhere and proliferate. Our dual cross-linking strategy has great potential in 3D bioprinting of tubular structure for biomedical applications, especially for artificial blood vessels.

Photocontrolled RAFT Polymerization Catalyzed by Conjugated Polymers under Aerobic Aqueous Conditions.

Photocontrolled polymerization offers a convenient way to direct the reaction progress and tailor the polymer structures. Nevertheless, conjugated polymers are yet to be utilized as the photocatalyst in associated reactions. Herein, we employed poly(boron dipyrromethene-alt-fluorene) (PBF), a conjugated polymer with better photostability than eosin Y, as the photocatalyst for photo-RAFT polymerizations of acrylic monomers, and the polymers were obtained with moderately narrow molecular weight distributions. The reaction progress was effectively controlled by switching irradiation conditions, and the block copolymers were prepared from chain extension of a macroinitiator. As electron spin resonance (ESR) and optical spectra results suggested, the reductive quenching of PBF* by ascorbate was the key step leading to the reduction of a chain transfer agent (CTA), whereas the hydroxyl radical derived from superoxide was considered as a byproduct of deoxygenation.

In vitro bond strengths of amalgam added to existing amalgams.

This study determined if a standardized condensation force and dwell time per condensation pressure point could reliably bond new amalgam to older amalgam without applying extrinsic Hg. A stabilization jig was created to hold 15 friction-fit 1-inch diameter (25 mm) cylindrical resin specimen blocks face up with cavities drilled to contain the condensed primary amalgam (Valiant PhD-XT). Freshly mixed secondary amalgam (Valiant PhD-XT) was condensed against the primary amalgam surfaces through the 3.5-mm-diameter central holes of specially fabricated split-ring molds. The 15 disks fit snugly within the holes of the stabilization jig tray. Condensation was with a consistent, calibrated force of 22.5 MPa (4 lbs/0.79 mm2) applied with a spring-loaded amalgam carrier custom adapted with a 1-mm-diameter stainless steel condenser tip. Secondary amalgam additions were built up in three 1-mm thick increments with a pattern of eight 22.5 MPa two-second condenser strokes per incremental layer. Shear-bond testing with a 1-mm/minute crosshead speed occurred 24-hours post-condensation. One-way analysis of variance statistical analysis was conducted to analyze the results. The mean shear-bond forces (MPa, N = 15) found were: Control 28.1 +/- 5, 15 minutes 31 +/-5, one hour 10.7 +/-4 (N = 30), one day 25.5 +/- 4, one week 25.2 +/- 4, two months 25.1 +/- 5 and seven years 24.7 +/- 4. Under the condensation pressures used in the current study, the addition of new amalgam to smooth previously set amalgam surfaces, not including the one-hour group, up to seven years old, resulted in shear-bond forces not statistically different (p = 0.05) from the intact control. Virtually all (94%) of the bonds tested, except for the one-hour sample, resulted in cohesive rather than adhesive failures except those of the one-hour sample. Forty percent bond strengths of the controls were achieved when only 5.6 MPa (1 lb/0.79 mm2) and 14 MPa (2.5 lb/0.79 mm2) condensation pressures were used.

In vitro staining of resin composites by liquids ingested by children.

PURPOSE: The purpose of this study was to compare the influence of various children's drinks on the discoloration of dental resin composites. METHODS: Ninety-six disks (3-mm thick, 10 mm in diameter) were prepared from 3 types of composite: (1) submicron; (2) nono; and (3) microhybrid. After polishing and obtaining baseline data, they were equally divided into 4 groups and immersed into 1 of 4 liquids at 37 degrees C: (1) distilled water; (2) Kool-Aid Jammers (grape flavor); (3) Coca-Cola; or (4) snow cone syrup (banana flavor). On days 3, 6, 9, 12, and 15, the samples were measured again for color. On day 18, they were measured for both color and gloss. RESULTS: Overall, the color change during the staining procedure was minimal (deltaE(ab) < 1.67) for all 3 composites, although it appeared that Tetric EvoCeram had the least discoloration. Using 3-way analysis of variance and linear regression analysis, only Estelite sigma in Coco-Cola showed a statistically significant linear relationship between discoloration and stain time. CONCLUSIONS: Three composites reacted differently in various staining solutions. During this study, the 4 solutions did not discolor any of the composites in a way that was clinically significant Tetric EvoCeram may be the most stain resistant material among the 3 tested.

Photoactive Oligo( p-phenylenevinylene) Functionalized with Phospholipid Units for Control and Visualization of Delivery into Living Cells.

To take advantage of the excellent optical properties of conjugated polymers (CPs) or conjugated oligomers (COs) for biological applications, there is still a requirement to find new ways to deliver these conjugated molecular materials into cells in a facile, controllable, and noninvasive manner. Herein, a photoactive oligo( p-phenylenevinylene) (OPV) derivative was covalently attached with phospholipid units (OPV-lipid) to enhance its dispersion in water and facilitate its internalization by cells. OPV-lipid could be delivered into either the cell membrane or cytoplasm controllably through the assistance of liposomes with different formulas. It could also act as a fluorescent probe for cell imaging and visualization of the delivery process. This work shows a good potential for delivering functional conjugated molecular materials into cells in a controllable way.

Conjugated Polymer-Based Photoelectrochemical Cytosensor with Turn-On Enable Signal for Sensitive Cell Detection.

In this work, a new photoelectrochemical (PEC) cytosensor was constructed by using cationic polyfluorene derivative, poly(9,9-bis(6'-(N,N,N,-trimethylammonium)hexyl)fluorene-co-alt-1,4-phenylene)bromide (PFP) as the photoelectric-responsive material for sensitive cell detection. Positive-charged PFP with high photoelectric conversion efficiency can generate robust photocurrent under light illumination. In the PEC cytosensor, 3-phosphonopropionic acid was linked to the indium tin oxide electrode, followed by modification with antiepithelial-cell-adhesion-molecule (EpCAM) antibody via amide condensation reaction. Thus, target SKBR-3 cells with overexpressed EpCAM antigen could be captured onto the electrode via the specific antibody-antigen interactions. Upon adding cationic PFP, a favorable electrostatic interaction between cationic PFP and negatively charged cell membrane led to a turn-on detection signal for target SKBR-3 cells. This new cytosensor not only exhibits good sensitivity because of the good photoelectric performance of conjugated polymers, but also offers decent selectivity to target cells by taking advantage of the specific antibody-antigen recognition.

Risk Factors for the Occurrence of Insufficient Cement Distribution in the Fractured Area after Percutaneous Vertebroplasty in Osteoporotic Vertebral Compression Fractures.

BACKGROUND: Insufficient cement distribution (ICD) in the fractured area has been advocated to be responsible for unsatisfied pain relief after percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fractures (OVCFs). However, little is known about risk factors for the occurrence of ICD. OBJECTIVE: The present study aimed to identify independent risk factors of the emergence of ICD. STUDY DESIGN: A retrospective cohort study. SETTING: Department of spinal surgery, an affiliated hospital of a medical university. METHODS: Patients who underwent PVP for single-level OVCF from January 2012 to September 2014 and met this study's inclusion criteria were retrospectively reviewed. Associations of ICD with co-variates (age, gender, bone mass density with a T-score, amount of injected cement, cement leakage, fracture level, fracture age, fracture severity grade, and location of the fractured area) and the influence of ICD on pain relief were analyzed. RESULTS: A total of 225 patients were included. ICD was found in 26 (11.6%) patients. Fractured area located in the superior portion of the index vertebra was significantly associated with occurrence of ICD. No further significant associations between the studied co-variates and emergence of ICD were seen in the adjusted analysis. In addition, patients with ICD had significantly higher immediate postoperative visual analog scale scores of back pain compared with those with sufficient cement distribution in the fractured area. LIMITATION: Location of the fractured area and cement distribution in the fractured area could not be evaluated quantitatively. CONCLUSIONS: The incidence of ICD is higher in patients with the fractured area located in the superior portion of the index vertebra and ICD might be responsible for unsatisfied pain relief after PVP for OVCFs. KEY WORDS: Percutaneous vertebroplasty, insufficient cement distribution, fractured area, risk factor, osteoporosis, vertebral compression fracture, spine, unsatisfied pain relief, cement augmentation.

Changes in color and staining of dental composite resins after wear simulation.

OBJECTIVES: The objectives were to measure the discoloration as well as the change in staining of composite resins after wear simulation. METHODS: Generalized wear simulation was performed with a three-body wear testing device for 400,000 cycles for six composite resins. A flat-planed stylus made with polyacetal resin was loaded perpendicularly under a load of 76-80 N. Color of nonworn and worn areas was measured with a spectrophotometer before and after staining with 0.5% methylene blue solution. Nonworn surface served as a control. Differences in color between nonworn and worn surfaces were calculated to indicate the change in color due to wear. Color change after staining with 0.5% methylene blue solution for nonworn and worn surfaces was calculated to observe the changes in staining. RESULTS: Color difference (DeltaE(*) (ab)) between nonworn and worn surfaces was in the range of 0.8-1.4 before staining, which increased to 1.1-3.9 after staining. Color change by staining with methylene blue in nonworn surface was 6.8-20.6, and that in worn surface was 5.2-17.8. Therefore, staining in nonworn surface was higher than that in worn surface (p < 0.05). Generalized wear simulation for approximately 3 years of clinical service resulted in acceptable color change before staining (DeltaE(*) (ab) < 3.3). After staining, color difference between nonworn and worn surface increased to not-acceptable value in one composite resin investigated.

Enhanced Photothermal Bactericidal Activity of the Reduced Graphene Oxide Modified by Cationic Water-Soluble Conjugated Polymer.

Surface modification of graphene is extremely important for applications. Here, we report a grafting-through method for grafting water-soluble polythiophenes onto reduced graphene oxide (RGO) sheets. As a result of tailoring of the side chains of the polythiophenes, the modified RGO sheets, that is, RGO-g-P3TOPA and RGO-g-P3TOPS, are positively and negatively charged, respectively. The grafted water-soluble polythiophenes provide the modified RGO sheets with good dispersibility in water and high photothermal conversion efficiencies (ca. 88%). Notably, the positively charged RGO-g-P3TOPA exhibits unprecedentedly excellent photothermal bactericidal activity, because the electrostatic attractions between RGO-g-P3TOPA and Escherichia coli (E. coli) bind them together, facilitating direct heat conduction through their interfaces: the minimum concentration of RGO-g-P3TOPA that kills 100% of E. coli is 2.5 µg mL-1, which is only 1/16th of that required for RGO-g-P3TOPS to exhibit a similar bactericidal activity. The direct heat conduction mechanism is supported by zeta-potential measurements and photothermal heating tests, in which the achieved temperature of the RGO-g-P3TOPA suspension (2.5 µg mL-1, 32 °C) that kills 100% of E. coli is found to be much lower than the thermoablation threshold of bacteria. Therefore, this research demonstrates a novel and superior method that combines photothermal heating effect and electrostatic attractions to efficiently kill bacteria.

Influence of fluorescent and opalescent properties of resin composites on the masking effect.

The objective of this study was to determine the influence of fluorescent properties in the reflectance and transmittance modes and opalescent properties and translucency under ultraviolet (UV)-included and -excluded conditions on the masking effect of commercial resin composites quantitatively. Color and spectral distribution of seven resin composites (14 shades) of 1-mm thick were measured in the reflectance and transmittance modes under UV-included and -excluded conditions. For the fluorescence evaluation, subtraction spectra by the inclusion and exclusion of the UV component of the illumination in the reflectance and transmittance modes were calculated. Opalescence parameter (DeltaO*(ab)) was calculated as the difference in yellow-blue (Deltab*) and red-green (Deltaa*) coordinates between the reflected and transmitted colors under UV-included and -excluded conditions. Under UV-included and -excluded conditions, translucency parameter (TP) was calculated and masking effect was calculated as the color difference between a specimen over a black tile and black tile itself. Fluorescent and opalescent properties varied by the brand and shade of composites and measurement protocols. Masking effect was correlated with TP values when TP values of materials were obviously different. But when TP values were in the similar range, the opalescent property influenced the masking effect of resin composites. The influence of fluorescent property on masking effect was also confirmed, although the degree of correlation was very low.

Changes in opalescence and fluorescence properties of resin composites after accelerated aging.

OBJECTIVES: Opalescence and fluorescence properties and the correlated translucency and masking effect of resin composites may change after aging. The objective of this study was to determine the changes in opalescence and fluorescence properties of resin composites after accelerated aging for 150 kJ/m2. Changes in translucency and masking effect were also determined. METHODS: Color and spectral distribution of seven resin composites (A2 shade, 1-mm thick) were measured in the reflectance and transmittance modes under ultraviolet light (UV)-included and excluded conditions. Opalescence parameter (OP) was calculated as the difference in yellow-blue (Deltab*) and red-green (Deltaa*) coordinates between the reflected and transmitted colors under UV-included and excluded conditions. For the fluorescence evaluation, color differences (FL-Ref and FL-Trans) by the inclusion or exclusion of the UV-component of the standard illuminant D65 in the reflectance and transmittance modes were calculated. Under UV-included and excluded conditions, the translucency parameter (TP) was calculated, and the masking effect (ME) was calculated as the color difference between a specimen over a black tile and black tile itself. Repeated-measures 2-way analysis of variance at the significance level of 0.05 was performed for the values before and after aging. RESULTS: OP values in UV-included and excluded conditions did not change significantly after aging. FL-Ref and FL-Trans, TP values and ME values in UV-included and excluded conditions changed significantly after aging (p<0.05). The ranges of changes after aging in DeltaE*ab units were: OP, -0.50 to 0.74; FL, -1.19 to 0.15; TP, -1.37 to 0.13; and ME, -0.49 to 0.33. SIGNIFICANCE: Opalescence of resin composites did not change but fluorescence was not detected after accelerated aging for 150 kJ/m2. Translucency and masking effect changed significantly after aging.

Surface hardness of resin composites after staining and bleaching.

This study investigated the effect of 3 staining solutions and 3 over-the-counter tooth-bleaching systems on the microhardness of 2 dental resin composites. Forty-five specimens of Filtek Supreme and Esthet-X were randomly assigned to 3 groups. Over a 40-day test period, the specimens in each group (n=15) were immersed in 1 of the 2 staining solutions (coffee and red wine) or distilled water as the control for 3 hours a day at room temperature. The 15 specimens in each staining group were further randomly divided into 3 subgroups, and the specimens in each subgroup (n=5) were bleached using one of the bleaching agents (Night Effects, Simply White Night and Opalescence Quick). Surface hardness was measured at 24 hours after polymerization (baseline), after staining and after bleaching. Means and standard deviations were calculated, and the data were analyzed using repeated-measures analysis of variance and Duncan's Test. The microhardness of Esthet-X was significantly higher than Filtek Supreme at baseline (p<0.01). All specimens of both materials immersed in coffee and wine revealed a significant hardness decrease compared to baseline values (p<0.05). In the control group, microhardness was increased, and this increase was statistically significant for Filtek Supreme (p<0.05). After bleaching, there was a significant decrease in mean microhardness for all groups tested (p<0.05). No significant difference was found among bleaching agents.

Properties of a dental resin composite with a spherical inorganic filler.

This study compared the mechanical properties, generalized wear resistance and polymerization shrinkage of a resin composite filled with spherical inorganic filler to other commercial resin composites. Six dental resin composites were tested, including a submicron filled composite (Estelite sigma, Estelite), 1 nano-composite (Filtek Supreme, Supreme), 2 microfilled composites (Heliomolar; Renamel Microfill, Renamel) and 2 microhybrid composites (Esthet X Improved; Tetric Ceram). Compressive strength (CS), diametral tensile strength (DTS), flexural strength (FS), flexural modulus (FM), generalized wear resistance (WV) and polymerization shrinkage (PS) were evaluated for the 6 materials. The specimens were cured according to the manufacturers' instructions in appropriate molds, stored (37 degrees C water, 24 hours), then tested on an Instron testing machine (0.5 mm/minute). PS was tested according to the Archimedes method at 1, 24 and 48 hours continually after polymerization. Data were analyzed by analysis of variance. The results showed that CS values ranged from 252 to 298 MPa, DTS ranged from 35 to 54 MPa, FS from 73 to 140 MPa, FM from 4.8 to 11.1 GPa, WV from 0.037 to 0.086 mm(3) and PS at 24 hours from 2.17 to 3.96 vol%. Composite had statistically significant influence on the in vitro properties tested. Estelite performed similarly to nano-composite and microhybrid composites in mechanical properties and generalized wear resistance, while Estelite and Supreme had the lowest PS among the materials tested. The 2 microhybrid materials had similar properties, while the 2 microfilled composites were different for most properties tested. Overall, the microfilled composites had lower strength than the other composites except Renamel for CS. All the materials had a similar shrinkage pattern in that about 99% of shrinkage occurred in less than 24 hours.

Optical properties of four esthetic restorative materials after accelerated aging.

PURPOSE: To determine the differences in CIE L*, a*, and b* values, translucency parameter (TP), opalescence parameter (deltaO*ab), and color difference caused by the fluorescence (deltaE*ab-FL) of resin composite, glass-ionomer, resin-modified glass-ionomer, and compomer of A2 shade before and after accelerated aging. METHODS: Color and spectral distribution of the materials were measured according to the CIELAB color scale relative to the standard illuminant D65 in the transmittance and reflectance modes. Aging was performed in an accelerated aging chamber with an energy exposure of 150 kJ/m2. The translucency parameter (TP) was calculated as the color difference (deltaE*ab) of the specimen over white and black backgrounds. Opalescence parameter (deltaO*ab) was calculated as the difference in blue-yellow coordinate (deltab*) and red-green coordinate (deltaa*) between the transmitted and reflected colors of a 1 mm-thick specimen. Color difference by the fluorescence (deltaE*ab-FL) in reflectance mode was calculated as an index of fluorescence. Differences and changes in optical properties were analyzed by the repeated-measures ANOVA. RESULTS: Type of material and the mode of measurement (transmittance and reflectance) influenced CIE L*, a* and b* values significantly (P< 0.05) before aging. Accelerated aging influenced CIE L*, a* and b* values. Aging and the type of material influenced TP, deltaO*ab and deltaE*ab-FL values significantly (P< 0.05).

Measurement of opalescence of resin composites.

OBJECTIVES: Opalescence is an optical property, where there is light scattering of the shorter wavelengths of the visible spectrum, giving the material a bluish appearance under reflected light and an orange/brown appearance under transmitted light. The objective of this study was to determine the opalescence of resin composites with a color measuring spectrophotometer. METHODS: Colors of A2 and enamel or translucent shades of four resin composites and of an unfilled resin measured in the reflectance and transmittance modes were compared, and the opalescence parameter (OP) was calculated as the difference in blue-yellow coordinate (Deltab*) and red-green parameter (Deltaa*) between the reflected and transmitted colors of 1-mm thick specimens. The masking effect was calculated as the color difference between the color of a black background and the color of specimen over the black background. RESULTS: The range of OP in resin composites was 5.7-23.7, which was higher than that of the unfilled resin. However, there were significant differences among the brands and shades of the resin composites. SIGNIFICANCE: Opalescence varied by brand and shade of the resin composites, and contributed to the masking of background color along with translucency parameter. Some of the resin composites actually displayed opalescence.