Td-WTe2 is a topologically nontrivial material and exhibits a variety of physical properties, such as giant unsaturated magnetoresistance and the unconventional thermoelectric effect, due to its ...topological nature. It is also known to exhibit ultrafast topological phase transitions that restore its inversion symmetry by intense terahertz and mid-infrared pulses, and these properties demonstrate the possibility of ultrafast control of devices based on topological properties. Recently, a novel photo-induced topological phase transition by using polarization-controlled infrared excitation has been proposed, which is expected to control the material topology by rearranging the atomic orbitals near the Weyl point. To examine this topological phase transition, we experimentally studied the excitation-polarization dependence of the infrared-induced phase dynamics in a thin-layer of Td-WTe2. Time-resolved second harmonic generation (SHG) measurements showed that SHG intensity decreases after the infrared pump regardless of the polarization. Polarization-resolved infrared pump–probe measurements indicated that the polarization-selected excited state relaxes quite rapidly (i.e., within 10–40 fs). Considering these experimental results, we conclude that it is difficult to control the photo-induced phase transition through orbital-selective excitation owing to the rapid loss of carrier distribution created by polarization-selective excitation in thin-layer Td-WTe2 under our experimental condition. These results indicate that the suppression of the electron scattering process is crucial for experimentally realizing the photo-induced phase transition based on the polarization selection rule of the materials.
A new family of heterometallic catalysts based on trimetalated macrocyclic tris(salen) ligands and rare‐earth metals was prepared and structurally characterized. The LaZn3 system containing anionic ...ligands such as acetate plays a critical role in catalyzing the alternating copolymerization of cyclohexene oxide (CHO) and CO2 with a high proportion of carbonate linkages. Among the lanthanide metals, the CeZn3 system exhibits high catalytic activity with a turnover frequency (TOF) of over 370 h−1. NMR analysis of the complex and end‐group analysis of the polymer suggest that the acetate ligands are rapidly exchanged, not only among coordinated acetates, but also between coordinated acetates and added carboxylate anions. These unique properties make this the first example of telomerization for the copolymerization of CHO and CO2.
Homogeneous heterometallic complexes based on the trizincated macrocycle trisaloph and a rare‐earth metal showed high catalytic activity for the alternating copolymerization of cyclohexene oxide and CO2 with a high proportion of carbonate repeat units. The carboxylate anion of the ammonium salt initiates the telomerization, providing the polycarbonate with the corresponding carboxylate.
Heat transfer enhancement is essential in low Reynolds number flow because recent small heat exchangers require narrow flow passages. In the present study, we conducted direct numerical simulations ...of the channel flow to investigate the turbulence sustaining effect by feedback blowing and suction from the wall. The initial flow field corresponded to the fully developed turbulent channel flow, and the Reynolds number suddenly decreased at the beginning of the simulation. The results indicated that there are two approaches for the turbulence maintenance. If the amplitude of the blowing and suction is high, then the sensor detects the blowing and suction from the wall, and the velocity fluctuation corresponds to self-maintenance. Then, we obtained large heat transfer. However, the gain was small. If the amplitude is moderate, then the blowing from the wall to the low-speed streaky structures pushes up, and the suction attracts the high-speed streak toward the wall. The effect to increase the Reynolds shear stress and heat transfer results in the promotion of the turbulence and heat transfer with high gain.
Sacoglossan sea slugs are able to steal chloroplasts from their algal prey and acquire photosynthetic capacity (termed kleptoplasty). These ‘stolen’ plastids provide sea slugs with a long-term supply ...of organic carbon and energy. This augmented nutrient supply brings many benefits in terms of survival, body planning, reproductive traits, and body regeneration. However, the mechanisms of maintenance of chloroplasts and photosynthesis in sea slugs are poorly understood. Here, we introduce this mysterious phenomenon, including recent research findings, and consider its feasibility for synthetic biology, e.g., construction of artificial photosynthetic animal cells.
This study aimed to determine the influence of surface roughness of the color adjustment potential restoration of universal resin composites. A structural colored resin composite (Omnichroma, OC) and ...a pigment-employed universal shade resin composite (Beautifil Unishade, BU) were used. Each resin composite was placed in a cavity to determine its ability to match the color of artificial teeth. The surface of the resin composites was polished with #800- or #2000-grit SiC paper before performing color measurements. One-way analysis of variance and Tukey post hoc tests were performed (α=0.05). The color difference (ΔE*ab) ranged from 2.5–3.9 for OC and 1.8–8.7 for BU. OC has a more stable color adjustment than BU. The color adjustment potential of universal resin composites was affected by the surface roughness of the restorations.
A 39-year-old man was admitted because of cardiac arrest. Emergent coronary angiography revealed a preserved coronary blood flow; however, multiple-row detector computed tomography (MDCT) revealed ...that the proximal right coronary artery (RCA) was running inside the aortic wall, creating proximal stenosis without atherosclerotic changes. Surgical intervention with unroofing was performed; however, postoperative stenosis of the proximal RCA required additional coronary artery bypass grafting (CABG). Intraoperative findings during CABG did not reveal hematoma or coronary dissection. However, MDCT one year after CABG depicted improvement of the RCA and graft stenoses, suggesting that the post-unroof stenosis may have been caused by an inflammatory reaction after surgical intervention.
This study aimed to evaluate the bonding performance of self-adhesive flowable resin composites (SARs) to bovine teeth. Three SARs, one experimental, and two commercially available products, were ...used. The study parameters were shear bond strength (SBS), microleakage, and scanning electron microscopy (SEM) evaluation of bonding interfaces. The SBS of the materials was 14.1–15.1 MPa to enamel, 22.2–23.2 MPa to etched enamel, and 7.4–10.7 MPa to dentin. Specimens with pre-etching showed lower microleakage scores than those without pre-etching. SEM images of the interfaces of the materials showed excellent adaptation regardless of the substrate or etching mode. The study results indicate that enamel pre-etching can improve the bonding performance of SARs.
This study aimed to evaluate the influence of surface pretreatment on the shear bond strength of resin luting cement to saliva-contaminated resin core foundation. The surface free energy (γS) of the ...adherent surfaces was examined. The two-way analysis of variance revealed that the surface pretreatment and storage conditions had a significant effect on the strength of the bond to resin core foundation. The γS values of the saliva-contaminated group were significantly lower than those of the other groups, and they tended to improve after surface pretreatment. The tendency of improvement in γS values differed depending on the type of pretreatment agents. Surface treatment with solutions containing functional monomers is effective in removing saliva contaminants from the resin core foundation surfaces and in creating an effective bonding surface for the resin luting cement.
Objective
This controlled randomized clinical trial determined the whitening efficacy and the intensity and absolute risk of tooth sensitivity in dual whitening when prefilled at‐home whitening trays ...were used between in‐office whitening intervals.
Materials and Methods
An in‐office whitening agent containing 35% hydrogen peroxide was used. A prefilled tray with a whitening agent containing 6% hydrogen peroxide was used for at‐home whitening. Sixty‐six subjects were randomly assigned to three groups. Group I: at‐home whitening was performed 10 times between the in‐office whitening treatments. Group II: at‐home whitening was performed five times between the in‐office whitening treatments. Group III: only in‐office whitening was performed. The tooth color changes were evaluated using a spectrophotometer. A visual analog scale was used to express the pain intensity.
Results
All the groups showed increased ΔE*ab, ΔE00, and ΔWID with increased whitening sessions. Group I at the 3rd whitening session showed significantly higher ΔE*ab, ΔE00, and ΔWID than group III. Tooth sensitivity showed higher values up to 24 h after whitening.
Conclusions
Although dual whitening with the prefilled tray and in‐office whitening had higher whitening ability than in‐office whitening alone, the intensity and absolute risk of tooth sensitivity was similar.
Clinical Relevance
The dual whitening might produce faster and stronger whitening effects than in‐office whitening alone.
Non-destructive and quantitative investigation of density distribution of round tablets was the objectives of this study. The density distribution of round tablets was observed using X-ray computed ...tomography (X-ray CT). The distribution images were visualized by fractionating the CT images into 25 unit cells and averaging the CT number for each cell. The profiles of the distribution were analyzed with respect to the compression pressure by partial least squares (PLS) method. Analysis using the PLS method resulted in regression and loading vectors depicting the contribution of the change in density due to the variation of compression pressure. The vectors were also composed of 25 positions and used to reconstruct density mapping. The reconstructed maps quantitatively indicated the regions reflecting changes in density. At the upper and lower surface of tablets, increasing the compression pressure increased density in the edge region and decreased density in the center region. The center region under the upper surface was weakly affected by the pressure change. These results well agreed with the simulation results of finite elemental method. We suggest that the effects of compression pressure visually revealed in each region of the tablet by the X-ray CT and PLS methods are generated by density imbalance resulting from high pressure compression.
Display omitted
•Density distribution of tablets is visualized by X-ray CT numbers.•Increase in compression pressure leads reduction of density at the top and bottom.•The experimental results agree with simulation results of finite elemental method.
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