Local Structure Modulation Induced Highly Efficient Far-Red Luminescence of La1- xLu xAlO3:Mn4+ for Plant Cultivation.

Modulating the local environment around the emitting ions with component screening to increase the quantum yield and thermal stability is an effective and promising strategy for the design of high-performance fluorescence materials. In this work, smaller Lu3+ was introduced into the La3+ site in a Mn4+-activated LaAlO3 phosphor with the expectation of improving the luminescence properties via lattice contraction induced by cation substitution. Finally, a La1- xLu xAlO3:Mn4+ ( x = 0-0.04) perovskite phosphor with a high quantum yield of 86.0% and satisfactory thermal stability was achieved, and the emission peak at 729 nm well matches with the strongest absorption peak of the Phytochrome PFR. The favorable performances could be attributed to the suppressed cell volume and superior lattice rigidity after the substitution of Lu3+. This work not only obtains a highly efficient La1- xLu xAlO3:Mn4+ ( x = 0.02) phosphor, which holds great potential for application in plant-cultivation light-emitting diodes, but also provides an applicable strategy for further investigation of far-red-emitting phosphors.

Influence of therapeutic cancer radiation on the bond strength of an epoxy- or an MTA-based sealer to root dentine.

AIM: To evaluate the influence of radiation on root canal sealer push-out bond strength to dentine and sealer/dentine interface in teeth filled with AH Plus (Dentsply Ind. Com. Ltda, Petrópolis, RJ, Brazil) and MTA Fillapex (Angelus Ind. Prod. Odontológicos S/A, Londrina, PR, Brazil). METHODOLOGY: Thirty-two maxillary canines were selected and randomly assigned to 2 groups (n = 16): one group was not irradiated, and the other was subjected to a cumulative radiation dose of 60 Gy. Root canals were prepared with the Reciproc system (VDW GmbH, Munich, Germany), and each group was divided into 2 subgroups (n = 8) according to the sealer - AH Plus or MTA Fillapex - using the single-cone filling technique. Then, 1-mm-thick dentine slices were obtained from each root third for the push-out test to evaluate sealer bond strength to dentine and for scanning electron microscopy (SEM) to examine the sealer/dentine interface. Failure mode after debonding was determined with a stereomicroscope at ×25 magnification. Bond strength data were analysed by two-way anova with a split-plot design and post hoc Tukey's test (α = 0.05). RESULTS: Significantly lower bond strength (P < 0.0001) was obtained after irradiation (0.71 ± 0.20 versus 0.97 ± 0.29 MPa) and in specimens filled with MTA Fillapex (0.70 ± 0.18 MPa) compared with AH Plus (1.00 ± 0.27 MPa). Percentage of adhesive failures increased after radiation in all root thirds in the teeth filled with AH Plus. SEM revealed more gap-containing regions and fewer tags at the sealer/dentine interface in irradiated specimens, with more tag formation and fewer gaps with AH Plus sealer. CONCLUSIONS: Radiation was associated with a decrease in the push-out bond strength of sealers to intraradicular dentine and formation of more gaps and fewer tags at the sealer/dentine interface regardless of the sealer.

Examination of femtosecond laser matter interaction in multipulse regime for surface nanopatterning of vitreous substrates.

The paper presents our results on laser micro- and nanostructuring of sodium aluminosilicate glass for the permanent storage purposes and photonics applications. Surface structuring is realized by fs laser irradiation followed by the subsequent etching in a potassium hydroxide (10M@80 °C) for 1 to 10 minutes. As the energy deposited is lower than the damage and/or ablation threshold, the chemical etching permits to produce small craters in the laser modified region. The laser parameters dependent interaction regimes are revealed by microscopic analysis (SEM and AFM). The influence of etching time on craters formation is investigated under different incident energies, number of pulses and polarization states.

Color stability of white mineral trioxide aggregate.

OBJECTIVE: This study aims to evaluate the color stability of white mineral trioxide aggregate (WMTA) after irradiation with three different curing lights and with a fluorescent lamp in an oxygen-free environment. MATERIAL AND METHODS: Thirty samples of WMTA were divided into four experimental groups (three curing light and one fluorescent lamp) and one negative control group. The samples in the curing light groups were immersed in glycerine and were irradiated for 20, 60, and 120 s with a curing light. The samples in the fluorescent lamp group were immersed in glycerine and left on a laboratory shelf below a fluorescent lamp, whereas the negative control group was irradiated with a curing light without immersion in glycerine. A spectrophotometer was used to determine the color of each specimen before and after each light exposure and after 5 days. Data were analyzed using analysis of variance and Fisher's least significant difference test. RESULTS: All the groups showed discoloration except for the negative control group. At 20, 60, and 120 s, there were no significant differences between the Optilux and Bluephase groups (which were the darkest). The Demi group was the curing light experimental group that showed the lowest degree of discoloration (P = 0.0001). No differences were observed between the fluorescent lamp and the negative control groups. After 5 days, the fluorescent lamp group also showed darkening of the sample surface and there were no significant differences between this group and the other three experimental groups (P > 0.05). CONCLUSIONS: WMTA showed dark discoloration after irradiation with a curing light or fluorescent lamp in an oxygen-free environment. CLINICAL RELEVANCE: WMTA may cause tooth discoloration when it is used in a coronal position.

A new binary compound for the production of 124I via the 124Te(p,n)124I reaction.

The binary compound, aluminum telluride (Al(2)Te(3)), was investigated as a target material for the production of (124)I by way of the (124)Te(p,n)(124)I reaction on a low-energy cyclotron. The high melting point and formation of a glassy matrix upon heating provided a stable target material at irradiations up to 20 microA of 11 MeV protons. The 87% tellurium mass fraction and 95% iodine separation yield led to significantly higher quantities of iodine compared to traditional TeO(2)/6%Al(2)O(3) admixtures. Radiochemical analysis of distilled samples using ion chromatography showed that the product remained in the iodide form while supported in weak buffer solutions. Stable Te impurities in the radioiodine product were less than 0.5 microg following purification by ion exchange chromatography. Average thick target yields of 229+/-18 microCi/microAh were achieved, and typical production runs at 18 microA for three hours yielded 12 mCi at the end-of-bombardment. Total losses of the target material after each irradiation and distillation cycle were approximately 2%.

Effect of Laser-Activated Irrigation on the Push-Out Bond Strength of ProRoot Mineral Trioxide Aggregate and Biodentine in Furcal Perforations.

OBJECTIVE: The objective of the present study was to assess the effect of erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser-activated irrigation (LAI) of NaOCl on the push-out bond strength of furcal perforations repaired with ProRoot mineral trioxide aggregate (MTA) and Biodentine. BACKGROUND DATA: Several studies investigated the adhesion of calcium silicate-based cements after exposure to endodontic irrigants, while effect of LAI on bond strength remains to be elucidated. MATERIALS AND METHODS: Bur-cut furcal perforations with standard dimensions were created in 100 extracted human mandibular molars. Teeth were randomly distributed into two groups (n = 50/group) according to the repair material applied: (1) ProRoot MTA or (2) Biodentine. The specimens were further assigned into five subgroups according to the irrigation regimens used over the set materials: (a) distilled water with needle irrigation; (b) 5.25% NaOCl with needle irrigation; (c) distilled water with LAI; (d) 5.25% NaOCl with LAI; and (e) no irrigation (control). Bond strengths of the test materials were assessed by using push-out bond strength test. RESULTS: Biodentine showed significantly higher dislocation resistance than ProRoot MTA (p < 0.05). Laser activation of 5.25% NaOCl and distilled water did not significantly affect the push-out bond strength results (p > 0.05). CONCLUSIONS: Biodentine showed higher dislocation resistance than ProRoot MTA as a perforation repair material. Er,Cr:YSGG laser activation of irrigation aqueous solutions had no adverse effect on push-out bond strength of Biodentine and ProRoot MTA.

Material Properties of a Tricalcium Silicate-containing, a Mineral Trioxide Aggregate-containing, and an Epoxy Resin-based Root Canal Sealer.

INTRODUCTION: The aim was to compare the solubility, radiopacity, and setting times of a tricalcium silicate-containing (BioRoot RCS; Septodont, St Maur-des-Fossés, France) and a mineral trioxide aggregate-containing sealer (MTA Fillapex; Angelus, Londrina, Brazil) with an epoxy resin-based sealer (AH Plus; Dentsply DeTrey, Konstanz, Germany). METHODS: Solubility in distilled water, radiopacity, and setting time were evaluated in accordance with ISO 6876:2012. The solubility was also measured after soaking the materials in phosphate-buffered saline buffer (PBS). All data were analyzed using 1-way analysis of variance and the Student-Newman-Keuls test. RESULTS: After immersion for 1 minute in distilled water, BioRoot RCS was significantly less soluble than AH Plus and MTA Fillapex (P < .05). At all other exposure times, AH Plus was significantly less soluble than BioRoot RCS, whereas BioRoot RCS was significantly more soluble than the other 2 sealers (P < .05). All sealers had the same solubility in PBS and distilled water, except for BioRoot RCS after 28 days. At this exposure time, BioRoot RCS was significantly less soluble in PBS than in distilled water and less soluble than MTA Fillapex (P < .05). All BioRoot RCS specimens immersed in PBS had a surface precipitate after 14 and 28 days. The radiopacity of all sealers was greater than 3 mm aluminum with no statistical significant difference between the sealers (P > .05). The final setting time was 324 (±1) minutes for BioRoot RCS and 612 (±4) minutes for AH Plus. The difference was statistically significant (P < .05). MTA Fillapex did not set completely even after 1 week. CONCLUSIONS: The solubility and radiopacity of the sealers were in accordance with ISO 6876:2012. PBS decreased the solubility of BioRoot RCS.

Color stability of mineral trioxide aggregate and calcium enriched mixture cement.

AIM: To assess the effect of light irradiation and different immersion media on discoloration of white mineral trioxide aggregate (WMTA) and calcium enriched mixture (CEM) cement at different time intervals. METHODS: Enamel sections of 12 teeth were removed and six cavities were prepared in each tooth. The cavities were filled randomly either with WMTA or CEM and covered with transparent sealant. Half the specimens were irradiated for 160 sec (eight exposures of 20 sec each) and the remaining were irradiated for 40 sec (two exposures of 20 sec each); digital images were taken after each exposure. The teeth were stored in phosphate buffer saline, oxygen-rich medium and glycerin (n = 4). Digital images were obtained after 1, 3, 7, 14, and 28 days. Commission Internationale de I'E'clairage (CIE) color space system and Photoshop CS5 software were used to evaluate the discoloration. The color change (ΔE) and lightness (ΔL) values was analyzed using repeated measures anova and Tukey's Tukey's honest significant difference (HSD) test. RESULTS: The materials tested showed significant discoloration over time (WMT > CEM; P < 0.001). ΔE increased significantly while ΔL decreased in three media over time (P < 0.001). Greater duration of light curing caused a significant decrease in ΔL and ΔE values in both materials (WMTA > CEM; P < 0.001). CONCLUSION: Color stability of WMTA was inferior to CEM samples after exposure to different duration of irradiation and media over time.

Antibacterial and Odontogenesis Efficacy of Mineral Trioxide Aggregate Combined with CO2 Laser Treatment.

INTRODUCTION: Mineral trioxide aggregate (MTA) has been successfully used in clinical applications in endodontics. Studies show that the antibacterial effects of CO2 laser irradiation are highly efficient when bacteria are embedded in biofilm because of a photothermal mechanism. The aim of this study was to confirm the effects of CO2 laser irradiation on MTA with regard to both material characterization and cell viability. METHODS: MTA was irradiated with a dental CO2 laser using directly mounted fiber optics in the wound healing mode with a spot area of 0.25 cm(2) and then stored in an incubator at 100% relative humidity and 37°C for 1 day to set. The human dental pulp cells cultured on MTA were analyzed along with their proliferation and odontogenic differentiation behaviors. RESULTS: The results indicate that the setting time of MTA after irradiation by the CO2 laser was significantly reduced to 118 minutes rather than the usual 143 minutes. The maximum diametral tensile strength and x-ray diffraction patterns were similar to those obtained without CO2 laser irradiation. However, the CO2 laser irradiation increased the amount of Ca and Si ions released from the MTA and regulated cell behavior. CO2 laser-irradiated MTA promoted odontogenic differentiation of hDPCs, with the increased formation of mineralized nodules on the substrate's surface. It also up-regulated the protein expression of multiple markers of odontogenic and the expression of dentin sialophosphoprotein protein. CONCLUSIONS: The current study provides new and important data about the effects of CO2 laser irradiation on MTA with regard to the decreased setting time and increased ion release. Taking cell functions into account, the Si concentration released from MTA with laser irradiation may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue.

Pulsed optically detected NMR of single GaAs/AlGaAs quantum wells.

While nuclear magnetic resonance (NMR) is one of the most important experimental tools for the analysis of bulk materials, the low sensitivity of conventional NMR makes it unsuitable for the investigation of small structures. We introduce an experimental scheme that makes NMR spectra of single, nanometer-sized quantum wells possible with excellent sensitivity and selectivity while avoiding the spectral broadening associated with some alternative techniques. The scheme combines optical pumping and pulsed radiofrequency excitation of the nuclei with time-resolved detection of the free induction decay through the polarization of the photoluminescence.

Aluminium nitrate ceramics: a potential UV dosemeter material.

The ceramic material AlN-Y2O3 is proposed as a potential ultraviolet radiation (UVR) dosemeter using optically stimulated luminescence (OSL) and thermally stimulated luminescence (TL). Experimental studies have shown that AIN ceramics exhibit attractive characteristics suitable for practical UV dosimetry applications. The features are: (1) the spectral sensitivity covers the 200-350 nm range, in the UV-B region it is similar to that of human skin; (2) the angular dependence of the incident radiation follows the cosine law; (3) high yields of both UVR-induced OSL and TL signals compared to those of Al2O3:C; and (4) a large dynamic range TL signal (5 orders of magnitude). Although there is relatively high fading, it is demonstrated that AIN is a feasible material for UVR dosimetry using short integration times.

A new effective thermoluminescent material: LiCaAlF6:Ce.

Absorption, emission and thermostimulated luminescence (TSL) of as-grown and X ray irradiated pure and Ce-doped LiCaAlF6 crystals were investigated. Ce-containing samples demonstrate intensive TSL in the UV region (280-310 nm) with a main peak at 350 degrees C. It is found that the well known UV laser crystal LiCaAlF6:Ce is a promising thermoluminescent dosemetric material.

Microwave-assisted synthesis of Zn/Al layered double hydroxide-(anthraquinone-2,6-disulfonate) nanocomposite.

Nanocomposites of Zn/Al-layered double hydroxide(anthraquinone-2,6-disulfonate) were synthesized by spontaneous direct assembly of inorganic and organic phases from aqueous solution. Powder X-ray diffraction patterns showed that a pure, single nanocomposite phase of good crystallinity was obtained using 1.0 M antraquinone-2,6-disulfonate ion (AQ26) and aging at 80 degrees C using conventional heating for 7 days or 0.5 h under microwave radiation, and these samples are denoted as ZAAN26C or ZAAN26MH, respectively. Zn/Al-nitrate-layered double hydroxide synthesized by a conventional method (ZANLC) showed a basal spacing of 8.3 A while both the nanocomposites showed 18.8 A as a result of AQ26 intercalation. FTIR study showed that the resulting nanocomposites are free from nitrate, the co-anion present in the mother liquor, indicating that only AQ26 is preferred during intercalation for the formation of the nanocomposite. The Brunauer, Emmet and Teller (BET) and micropore surface areas for ZAAN26C decreased relative to the ZANLC from 16.2 to 4.7 and 1.6 to 1.3 m2/g, respectively. These results indicate that AQ26 can be rapidly interdcalated in layered double hydroxide using microwave-aging resulting in a nanocomposite.

FEM simulation of Rayleigh waves for CMOS compatible SAW devices based on AlN/SiO2/Si(100).

A simulation study of Rayleigh wave devices based on a stacked AlN/SiO2/Si(100) device was carried out. Dispersion curves with respect to acoustic phase velocity, reflectivity and electromechanical coupling efficiency for tungsten W and aluminium Al electrodes and different layer thicknesses were quantified by 2D FEM COMSOL simulations. Simulated acoustic mode shapes are presented. The impact of these parameters on the observed Rayleigh wave modes was discussed. High coupling factors of 2% and high velocities up to 5000 m/s were obtained by optimizing the AlN/SiO2 thickness ratio.

Effect of ultrasonication on physical properties of mineral trioxide aggregate.

AIM: To evaluate the effect on physical properties of Mineral Trioxide Aggregate (MTA) of using direct hand compaction during placement and when using hand compaction with indirect ultrasonic activation with different application times. METHODS: One hundred acrylic canals were obturated in 3 increments with MTA in sample sizes of 10. One group was obturated by hand with an endodontic plugger and the remainder obturated with indirect ultrasonic application, with times ranging from 2 seconds to 18 seconds per increment. Microhardness values, dye penetration depths, and radiographs of the samples were evaluated. RESULTS: As ultrasonic application time per increment increased, microhardness values fell significantly (P < 0.001) while dye penetration values increased (P < 0.001). Microhardness of MTA ultrasonicated for 2 seconds was significantly higher than hand compaction (P = 0.03). Most radiographic voids were visible in the hand-compacted group (P < 0.001), which also had higher dye penetration depths than the 2-second ultrasonicated samples. Ultrasonication of MTA for 10-18 seconds resulted in significantly more voids than 2-8 seconds of ultrasonication (P = 0.02). CONCLUSION: The use of ultrasonics with MTA improved the compaction and flow of MTA, but excessive ultrasonication adversely affected MTA properties. A time of 2 seconds of ultrasonication per increment presented the best compromise between microhardness values, dye penetration depths, and lack of radiographic voids.

Effects of diode laser and MTAD on the push-out bond strength of mineral trioxide aggregate-dentin interface.

OBJECTIVE: The aim of this in vitro study was to evaluate the effects of diode laser, MTAD(™) and laser plus MTAD on the push-out bond strength of mineral trioxide aggregate (MTA)-dentin. BACKGROUND DATA: MTA has been used widely, especially in root canal therapies (RCT); however, the effect of different final treatments during RCT has been questioned regarding the retention characteristic of this cement-based material. MATERIALS AND METHODS: Forty single-rooted human teeth were prepared into dentin slices and drilled to form canal spaces. Samples were divided into four groups of 10 in each (n=10). In groups A and B, diode laser irradiations were performed, and then MTA was placed inside the canal spaces and incubated at 37 °C for 7 days. After incubation, dentin slices in groups B and C were immersed in Biopure MTAD, and the last group served as control without any treatment. The push-out bond strengths were then measured by using a universal testing machine. RESULTS: The means±standard deviations of push-out bond strength were 6.74±0.48, 5.95±0.40, 6.86±0.66, and 7.88±0.37 for groups A (laser), B (laser plus MTAD), C (MTAD) and D (control), respectively. One-way analysis of variance (ANOVA) test revealed significant differences among the groups (p<0.0001). Tukey's test did not show any significant difference between groups A and C (p=0.93). However, these differences were significant between groups A and B (p=0.006) and between groups B and C (p=0.001). CONCLUSIONS: The results of this study indicated that either diode laser or MTAD can lower the bond strength of MTA-dentin, and that diode laser irradiations plus MTAD might affect MTA bond to dentin negatively.

Resistivity studies on the layered semi-metallic CaAl2Si2: evaluating its temperature-, field- and pressure-dependence.

We studied the layered, hexagonal, semi-metal CaAl(2)Si(2) by magnetization, specific heat and resistivity measurements over a wide range of temperature, pressure and magnetic field. Both the Sommerfeld coefficient (γ = 1 mJ mol(-1) K(-2)) and the Debye temperature (θ(D) = 288 K) are in agreement with the values obtained from the band structure calculation. The resistivity shows a metallic character up to 200 K, followed by saturation and, afterwards, a weak decrease up to 840 K, at which it sharply rises reaching a local maximum at 847 ± 5 K. While the low-temperature thermal evolution was accounted for in terms of intrinsic and extrinsic effects, the additional high-temperature scattering was attributed, based on differential thermal analysis, to a first-order thermal event. No appreciable magnetoresistivity was observed at liquid helium temperatures even for fields up to 90 kOe, indicating an absence of coupling between the electronic and magnetic degrees of freedom. Finally, an externally applied pressure was found to induce a strong reduction in the resistivity following a second-order polynomial: this effect will be discussed in terms of the influence of pressure on the effective mobility and concentration of charge carriers.

Radiopacity evaluation of calcium aluminate cement containing different radiopacifying agents.

INTRODUCTION: The aim of this study was to evaluate the radiopacity of calcium aluminate cement (EndoBinder) with 3 different radiopacifiers (bismuth oxide, zinc oxide, or zirconium oxide) in comparison with gray mineral trioxide aggregate (GMTA), white MTA, and dental structures (enamel and dentin). METHODS: Eighteen test specimens of each cement with thicknesses of 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm (n = 3) were made by using a stainless steel matrix and were adapted to a standardizing device (8 × 7 cm) with a graduated aluminum stepwedge varying from 2.0-16.0 mm in thickness. To compare the radiopacity of the cements with that of dental structures, slices of first molars with a thickness increasing from 0.5-3.0 mm were obtained and placed on the standardizing device. One occlusal radiograph for each tested cement was taken, with exposure time of 0.1 seconds and focus-film distance of 20 cm. Films were processed in an automatic device, and the mean radiopacity values were obtained by using a photodensitometer. RESULTS: Mean values showed that the thicker the specimen was, the greater was its radiopacity. Only EndoBinder + bismuth oxide (EBBO) and GMTA demonstrated radiopacity values greater than 3.0 mm of the aluminum scale for all thicknesses. When zinc oxide was used as radiopacifier agent, EndoBinder only reached the desired radiopacity with a thickness of 2.0 mm, and with zirconium oxide it was 2.5 mm. CONCLUSIONS: Bismuth oxide was the most efficient radiopacifier for EndoBinder, providing adequate radiopacity in all studied thicknesses, as recommended by ISO 6876, being similar to GMTA.

Exciton localization in vertically and laterally coupled GaN/AlN quantum dots.

Near-field and time-resolved photoluminescence measurements show evidence of exciton localization in vertically and laterally coupled GaN quantum dots (QDs). The binding energies in multiple period QDs (MQDs) are observed to be stronger by more than six times compared to single period QDs (SQDs). Excitons in MQDs have a short (450 ps) lifetime and persist at room temperature, while SQDs exhibit extraordinarily long (>5 ns) lifetime at 10 K due to reduced spatial overlap of electron and hole wave functions in strained QDs.

Curing depths of a universal hybrid and a flowable resin composite cured with quartz tungsten halogen and light-emitting diode units.

This in vitro study evaluated curing depths of a universal hybrid resin composite with two viscosities (Tetric Ceram and Tetric Flow) after curing with 6 different quartz tungsten halogen and light-emitting diode curing units. Irradiance (light intensity) of the curing units varied between 200 and 700 mW/cm2. The curing units were used for standard, soft-start, or pulse curing. Curing times were 20 and 40 s for standard curing, 3 + 10 s and 3 + 30 s for pulse curing, and 40 s for soft-start. Resin composite specimens, 5 in each group, with a diameter of 4 mm and a height of 6 mm, were made in brass molds and cured from one side at a distance of 6 mm. After 2 weeks, the specimens were ground longitudinally half through the specimen. Curing depth was then determined by measurement of Wallace hardness for each half millimeter starting at 0.5 mm from the top surface. For all curing units and for both resin composites an increased curing time led to statistically significantly higher depth of cure (P < 0.0005). Tetric Flow showed a statistically significantly higher depth of cure than Tetric Ceram (P < 0.0005). All curing units cured more than 2.0 mm of both composites from a distance of 6 mm at 20 s curing time. The value for 40 s was 3.0 mm. The composite closer to the surface than the depth of cure value was equally well cured with all curing units investigated. There was a significant linear correlation between the determined irradiance of the curing units and the depths of cure obtained (20s: r = 0.89, P < 0.025; 40 s: r = 0.91, P < 0.01).