We report the design and demonstration of a dual-stimuli-responsive block copolymer (BCP) micelle with increased complexity and control. We have synthesized and studied a new amphiphilic ABA-type triblock copolymer whose hydrophobic middle block contains two types of stimuli-sensitive functionalities regularly and repeatedly positioned in the main chain. Using a two-step ...

Since the late 1990s, rising sea levels around the Torres Islands (north Vanuatu, southwest Pacific) have caused strong local and international concern. In 2002-2004, a village was displaced due to increasing sea incursions, and in 2005 a United Nations Environment Programme press release referred to the displaced village as perhaps ...

BiOCl/BiOI composites with a visible light response were prepared by a simple hydrothermal method. Even though both single BiOCl and BiOI show low photocatalytic activity, BiOCl/BiOI composites provide enhanced efficiency in decomposing organic compounds including Methyl Orange (MO) and Rhodamine B (RhB). Furthermore, the 20%BiOCl/BiOI composite shows the highest efficiency ...

After darkening, isoprene emission continues for 20 to 30 min following biphasic kinetics. The initial dark release of isoprene (postillumination emission), for 200 to 300 s, occurs mainly at the expense of its immediate substrate, dimethylallyldiphosphate (DMADP), but the origin and controls of the secondary burst of isoprene release (dark-induced ...

Photophysiological and pharmacological approaches were used to examine light-induced germination of resting spores in the red-tide diatom Leptocylindrus danicus. The equal-quantum action spectrum for photogermination had peaks at about 440 nm (blue light) and 680 nm (red light), which matched the absorption spectrum of the resting spore chloroplast, as well ...

The possible role of L-ascorbate (AsA) as a biochemical signal during the interactions between photosynthesis and respiration was examined in leaf discs of Arabidopsis thaliana. AsA content was either decreased as in AsAdeficient vtc1 mutants or increased by treatment with L-galactono-1, 4-lactone (L-GalL, a precursor of AsA; EC 1.3.2.3). In ...

In C(4) plants, mesophyll (M) chloroplasts are randomly distributed along the cell walls, whereas bundle sheath chloroplasts are located in either a centripetal or centrifugal position. It was reported previously that only M chloroplasts aggregatively redistribute to the bundle sheath side in response to extremely strong light or environmental stresses. ...

In maize (Zea mays L.), chloroplast development progresses from the basal meristem to the mature leaf tip, and light is required for maturation to photosynthetic competence. During chloroplast greening, it was found that chloroplast DNA (cpDNA) is extensively degraded, falling to undetectable levels in many individual chloroplasts for three maize ...

Chloroplasts change their positions in the cell depending on the light conditions. In the dark, chloroplasts in fern prothallia locate along the anticlinal wall (dark position). However, chloroplasts become relocated to the periclinal wall (light position) when the light shines perpendicularly to the prothallia. Red light is effective in inducing ...

Paphiopedilum and Cypripedium are close relatives in the subfamily Cypripedioideae. Cypripedium leaves contain guard cell chloroplasts, whereas Paphiopedilum without. It is unclear whether lack of guard cell chloroplasts affects photosynthetic induction, which is important for understory plants to utilize sunflecks. To understand the role of guard cell chloroplasts on photosynthetic ...

Phytochromes are red and far-red light photoreceptors that regulate various aspects of plant development. One of the less-understood roles of phytochromes is the inhibition of hypocotyl negative gravitropism, which refers to the loss of hypocotyl gravitropism and resulting random growth direction in red or far-red light. This light response allows ...

Mitochondrial alternative oxidase (AOX), the unique respiratory terminal oxidase in plants, catalyzes the energy wasteful cyanide (CN)-resistant respiration and plays a role in optimizing photosynthesis. Recent studies from our group indicated that AOX plays a crucial role in chloroplast protection under extreme environments, such as high light (HL). Genetic data ...

The effects of light and methyl jasmonate (MJ) on the transcription of biosynthetic genes as well as the accumulation of vindoline and catharanthine in Catharanthus roseus C20hi cell suspensions were studied. t16h (the gene encoding tabersonine 16-hydroxylase) could be induced by light and MJ, whereas d4h (the gene encoding deacetoxyvindoline ...

Chloroplast movement in response to changing light conditions optimizes photosynthetic light absorption. This repositioning is stimulated by blue light perceived via the phototropin photoreceptors and is transduced to the actin cytoskeleton. Some actin-based motility systems use filament reorganizations rather than myosin-based translocations. Recent research favors the hypothesis that chloroplast movement ...

Chloroplast photorelocation movement towards weak light and away from strong light is essential for plants to adapt to the fluctuation of ambient light conditions. In the previous study, we showed that blue light receptor phototropins mediated blue light-induced chloroplast movement in Arabidopsis by regulating short actin filaments localized at the ...

The aim of this study was to evaluate the influence of different curing lights and chemical catalysts on the degree of conversion of resin luting cements. A total of 60 disk-shaped specimens of RelyX ARC or Panavia F of diameter 5 mm and thickness 0.5 mm were prepared and the respective chemical ...

To compare the ability of four light-emitting diode (LED) curing lights to polymerize five composite resins in 10 seconds at 4 and 8 mm. Two second-generation, single-peak LED curing lights (Bluephase 16i, Ivoclar Vivadent, and LEDemetron II, Kerr) and two third-generation polywave LED curing lights (UltraLume 5, Ultradent, and Bluephase ...

In this in-vitro study, we aimed to compare the residual monomers in composites beneath brackets bonded to enamel, using a light-emitting diode (LED) or a halogen unit, and to compare the residual monomers in the central to the peripheral areas of the composite. Twenty bovine teeth preserved in 0.1% thymol ...

The aim of this study was to compare the microhardness of five different resin composites at different irradiation distances (2 mm and 9 mm) by using three light curing units (quartz tungsten halogen, light emitting diodes and plasma arc). A total of 210 disc-shaped samples (2 mm height and 6 ...

As discussed in Part I, the type of curing light and curing mode impact the polymerization kinetics of resin-based composite (RBC) materials. Major changes in light-curing units and curing modes have occurred. The type of curing light and mode employed affects the polymerization shrinkage and associated stresses, microhardness, depth of ...

There has been a continual advent of improved technologies in dentistry. Among these are the material sciences of resin-based composites (RBCs). Since the introduction of light-cured RBCs, the problem of polymerization shrinkage and the methods used to overcome this have concerned clinicians and researchers. Types of curing light and modes ...

A facile strategy based on the amidation reaction of anhydride and NH(2) group in carbon nitride polymer is developed to synthesize a new polymeric photocatalyst which responds to visible-light. The high photocatalytic activity may be due to the coupling anhydride groups promoting the separation of the photoinduced electrons and holes.

To evaluate the translucency, opalescence and light transmission characteristics of resin composites with different thicknesses. Disks of three resin composites (Estelite∑, Beautifil II, Clearfil Majesty) of A2 shade were prepared in diameter of 10mm with various thicknesses (0.5mm, 1.0mm and 2.0mm). Color was measured according to CIELAB color scale on ...

This study investigated the influence of time delay and duration of photo-activation on linear polymerization shrinkage, shrinkage force, and hardening of a dual-cured core build-up resin composite. The test material (Rebilda DC) was light-cured for 20 or 60 s either early (2 min) or late (7 min) after the start ...

The aim of this study was to compare the shear bond strength (SBS) of two different light sources under different thermal cycle frequencies. Ninety human premolar teeth were divided into six groups, in which three groups consisted of halogen groups - Group I was cured with halogen without thermocycle, Group ...

The aim of this study was to evaluate: (i) the absorption of photo-initiators and emission spectra of light curing units (LCUs); and (ii) the degree of conversion (DC) of experimental composites formulated with different photo-initiators when activated by different LCUs. Blends of BisGMA, UDMA, BisEMA and TEGDMA with camphorquinone (CQ) ...

The purpose of this study was to assess the influence of two light units, a light-emitting diode (LED) and a plasma arc light (PAC), on the shear bond strength (SBS) of brackets bonded to enamel. Ninety bovine teeth were divided into six groups, according to the light-curing unit and exposure ...

The effect of a novel light curing process, namely soft light energy release (SLER), on shrinkage, mechanical strength and residual stress of four dental restorative materials (DEI experience, Gradia Direct, Enamel Plus HFO and Venus) was investigated. Composite specimens were fast cured through high level of power density and soft ...

Composite colloids were prepared via grafting optically responsive spiropyran polymer brushes onto silica colloids. Similar to spiropyran, the polymer brushes undergo a reversible inversion from a hydrophobic state to a hydrophilic state upon irradiation with UV light (or vice versa by visible light). The composite colloids can thus reversibly transfer ...

This study evaluated the shear bond strength (SBS) of orthodontic brackets bonded to teeth using a diode-pumped solid state (DPSS) laser of 473 nm with various light intensity and light-curing settings. For the study, a total of 150 extracted human teeth were divided into ten groups. In the control group, the ...

The temperature rises produced by two Quartz-Tungsten-Halogen (QTH) bulb and four solid-state light emitting diode (LED) light curing units (LCU's) was measured on five separate occasions following (i) activation for 40 seconds and (ii) three consecutive activations of 40 seconds. For both periods of activation evaluated the Luxor QTH LCU ...

PURPOSE: To examine in vitro orthodontic bonding sealants combined with daily fluoride (NaF) rinse on caries-like lesion depths. METHODS: Permanent molar teeth (n = 40) were randomly divided into four treatment groups: 1: Pro-Seal, 2: Light Bond, 3: Pro-Seal with NaF rinsing, and 4: Light Bond with NaF rinsing. Orthodontic ...

PURPOSE: To evaluate the effect of different curing protocols on marginal adaptation of ceramic inlays after thermomechanical loading (TML). MATERIALS AND METHODS: Forty-eight human molars were randomly divided into 6 groups (n = 8). After Class II cavity preparation (mod), ceramic inlays (Cerec) were fabricated. In groups I to IV, ...

We evaluated the curing efficiency of 4 high-intensity light-emitting diode (LED) devices by assessing percentage of residual C=C (%RDB), surface microhardness (SM), depth of cure (DC), percentage of linear shrinkage-strain (%LS), and percentage of wall-to-wall contraction (%WWC). The light-curing units tested were a QTH light, the Elipar TriLight (3M/ESPE), and ...

This laboratory study examined the effects of curing lights with different light intensities and changing flow rate on the increase in pulpal temperature during the light curing process and the rate of the subsequent decrease in temperature after the termination of light curing. The tip of a temperature sensor was ...

Light activation units are standard items of equipment in dental practice. It is essential to understand the many factors which affect the polymerization of light-activated resin composite materials and the choice of a light curing unit. In this respect, the development of high-intensity halogen and light-emitting diode (LED) light curing ...

STATEMENT OF PROBLEM: Upon removal, tear forces occur in various areas of an impression. As a result, thin sulcus details may be permanently deformed, affecting the impression's accuracy. PURPOSE: The purpose of this study was to investigate the effect of the chemistry and prolonged setting time on the permanent deformation ...

OBJECTIVES: The purpose of this study was to develop and evaluate a dynamic light scattering-based method for monitoring the polymerization reaction of a light activated dental composite. METHODS: Laser light back-scattered from thin disk-shaped composite samples was used to study the curing reaction kinetics. Samples were irradiated simultaneously on opposite ...

The irradiance from dental light-curing units (LCUs) is commonly reported as a single number, but this number does not properly describe the light output. This study examined the irradiance uniformity and distribution from a variety of LCUs as well as the effect of different light guides. Five LCUs representing quartz-tungsten-halogen, ...

OBJECTIVE: The aim of this investigation was to determine reaction enthalpy, ion viscosity and curing light transmission changes of unfilled methacrylate-based systems in order to compare methods that monitor photoactive resin polymerization. METHODS: Photoinitiator (0.2%, w/v, camphoroquinone), accelerator (0.3%, w/v, amine) and inhibitor (ranging from 0 to 1%, w/v, butylated ...

This paper assesses the effects of light characteristics and irradiation time on the Vickers microhardness (VH) of a dual-photoinitiator commercial composite and on temperature increase in the pulp chamber (deltaT). Four recent light-emitting diodes (LEDs)--bluephaseG2 (BG2), bluephase16i (B16i), G-Light (G) and Freelight2 (F2)--and one control halogen light (XL3000-X) were tested ...

INTRODUCTION: In this in-vitro study, we evaluated the temperature changes in the pulp chamber during bracket bonding using 4 different light sources. METHODS: Eighty intact extracted maxillary central incisors were used. The teeth were divided into 4 groups of 20 teeth each. Brackets (Mini Twin, Dentaurum, Ispringen, Germany) were bonded ...

OBJECTIVES: The aim of this study was to measure the initial dynamic viscoelastic modulus change of dental composites during light curing using a custom made oscillation rheometer. METHODS: Six commercial universal hybrid resin composites: Z100 (Z1), Z250 (Z2), Z350 (Z3), DenFil (DF), Tetric Ceram (TC), and Clearfil AP-X (CF) were ...

WOLEDs offer new design opportunities in practical solid-state lighting and could play a significant role in reducing global energy consumption. Obtaining white light from organic LEDs is a considerable challenge. Alongside the development of new materials with improved color stability and balanced charge transport properties, major issues involve the fabrication ...

OBJECTIVES: Evaluate the shear bond strength (SBS) and the adhesive remnant index (ARI) of indirect bonded lingual brackets using xenon plasma arc light, light-emitting diode (LED) and conventional quartz-tungsten-halogen light. MATERIAL AND METHODS: Lingual brackets were bonded indirectly to 60 premolars divided to three groups according to the curing light ...

Resin-modified glass ionomers (RMGI) set by at least 2 mechanisms dependent upon reactant diffusion prior to gelation. Each reaction's kinetics and setting mechanism may rely on and/or compete with the other. In this study, we investigated RMGI setting reaction interactions using differential scanning calorimetry (DSC) by varying light-cure initiation times. ...

We examined the light transmittance characteristics and refractive indices of light-activated pit and fissure sealants. Five commercial pit and fissure sealants and human enamel were studied, along with the CIE L*a*b* color values of the materials and enamel. The light transmittance spectra of the pit and fissure sealants showed a ...

PURPOSE: To measure the amount of light energy that dental students actually deliver to a Class I preparation in a dental mannequin. MATERIALS AND METHODS: Approval for the study was obtained from the Dalhousie University Health Sciences Research Ethics Board. Each of 20 third-year dental students light-cured a Class I ...

To determine the influence of the light curing units on the shear bond strength of orthodontic brackets. Seventy-two premolars were divided into six groups (n=12): Group I: brackets bonded with Transbond and polymerization with halogen light; Group II: Transbond and LED; Group III: Fuji Ortho and halogen light; Group IV: ...

This study evaluated the effect of different light energy densities on conversion degree (CD) and Knoop hardness number (KHN) of RelyX ARC (RLX) resin cement. After manipulation according to the manufacturer's instructions, RLX was inserted into a rubber mold (0.8 mm x 5 mm) and covered with a Mylar strip. ...