Atomic-layer transition metal dichalcogenides (TMDCs) have attracted appreciable interest due to their tunable band gap, spin-valley physics, and potential device applications. However, the quality ...of TMDC samples available still poses serious problems, such as inhomogeneous lattice strain, charge doping, and structural defects. Here, we report on the growth of high-quality, monolayer WS sub(2) onto exfoliated graphite by high-temperature chemical vapor deposition (CVD). Monolayer-grown WS sub(2) single crystals present a uniform, single excitonic photoluminescence peak with a Lorentzian profile and a very small full-width at half-maximum of 21 meV at room temperature and 8 meV at 79 K. Furthermore, in these samples, no additional peaks are observed for charged and/or bound excitons, even at low temperature. These optical responses are completely different from the results of previously reported TMDCs obtained by mechanical exfoliation and CVD. Our findings indicate that the combination of high-temperature CVD with a cleaved graphite surface is an ideal condition for the growth of high-quality TMDCs, and such samples will be essential for revealing intrinsic physical properties and for future applications. Keywords: WS sub(2); graphite; exciton; photoluminescence; line width; CVD growth
Abstract
We report the chemical vapor deposition growth of Nb-doped WS
2
monolayers and their characterization. Electron microscopy observations reveal that the Nb atom was substituted at the W site ...at a rate of approximately 0.5%. Unlike Mo doping, Nb-doped samples have photoluminescence (PL) peaks at 1.4–1.6 eV at room temperature. The peak energies are lower than the optical bandgap of 1.8 eV, and a saturation behavior of PL intensity is observed with the increase in excitation power. These results indicate that the observed PL peaks are assignable to the emission from impurity states generated by the substitution of Nb.
Measurements using an accelerometer reflect the impact applied to the trunk. Measurement of trunk acceleration has the possibility of reflecting the typical characteristics of trunk motion during ...cutting. However, analysis of trunk acceleration data during cutting manoeuvres has not been previously conducted. This study aimed to analyse trunk acceleration during cutting manoeuvres to examine any gender differences or a relationship with posture. All participants (eight male and eight female college soccer athletes) performed a shuttle run cutting task, and trunk accelerations (medio-lateral, vertical, and antero-posterior) were calculated. The peak acceleration (G) and total magnitude during the 200 ms after foot contact were measured, and the forward trunk inclination and femoral angle were calculated from the video images taken using a sagittal plane camera. Peak vertical acceleration (mean, s) was significantly greater among female athletes than among male athletes (−2.18, s = 0.84 G; −1.15, s = 0.45 G, respectively; p < 0.01). Medio-lateral and antero-posterior peak acceleration and the total magnitude in all directions were not significantly different between genders. Moderate negative correlations were found between vertical peak acceleration and trunk forward inclination and femoral inclination (r = −0.57, p < 0.05; r = −0.69, p < 0.01, respectively). The difference in vertical acceleration between genders has the possibility to reflect a stiff cutting movement among female athletes. The acceleration of the upper trunk may be an index for evaluating cutting movements.
Polymers molecularly imprinted toward bisphenol A (BPA-MIPs) were prepared by reverse atom transfer radical polymerization (reverse ATRP). For covalent bond-based BPA imprinting, a new template ...molecule, BPA di(4-vinyl benzoate), was synthesized and co-polymerized with divinylbenzene and styrene. Compared with conventional radical polymerization-based BPA-MIPs, the selectivities of the ATRP-based BPA-MIPs appear to be enhanced, suggesting that reverse ATRP could provide homogeneously cross-linked polymers and elaborate BPA recognition cavities in MIPs with size- and shape-selectivity.
Bisphenol A (BPA)-imprinted polymers prepared by reverse ATRP showed enhanced selectivity toward BPA compared with conventional radical polymerization-based MIPs, suggesting that control/living radical polymerization is effective for MIPs preparation.
Background: The risk of anterior cruciate ligament (ACL) injury is higher in female soccer players than in male soccer players. The most common reason for non-contact ACL injury has been found to be ...a cutting or stopping maneuver combined with deceleration and landing from a jump. In a previous study, there was no difference in the incidence of ACL injury between offensive and defensive players and in the risk of ACL injury between goalkeepers and other players. Recently studies reported that the most frequent injury situation was pressing in male players. However, the most common type of situation associated with ACL injury in female soccer players has not been clarified. Objectives: The purpose of the present study was to identify the most common type of situation associated with ACL injury in female soccer players. Methods: We handed out questionnaires to 80 female soccer players with a history of ACL injury (90 ACL injuries). The players were asked about the injury characteristics, injury circumstance, maneuver being performed when the injury occurred, and playing type associated with the injury. The players responded to the questionnaire under the guidance of the medical staff of each team. Results: The 80 female soccer players reported a total of 90 ACL injuries during soccer. Among 55 non-contact injuries, 29 (55%) occurred during a cutting maneuver and 22 (44%) occurred during pressing. On assessing the frequency distributions of playing type (pressing vs. others) and body contact (contact vs. no contact), we found that non-contact injuries at pressing were significantly more common than contact injuries at pressing (odds ratio: 3.03; 95% confidence interval, 1.11 - 8.25, P = 0.036) Conclusions: ACL injury often occurs as non-contact injury during pressing at the time of defense, regardless of the playing area, in female soccer players.
Mechanical anisotropy is an essential property for biomolecules to assume structural and functional roles in mechanobiology. However, there is insufficient information on the mechanical anisotropy of ...ligand–biomolecule complexes. Herein, we investigated the mechanical property of individual human telomeric G‐quadruplexes bound to telomestatin, using optical tweezers. Stacking of the ligand to the G‐tetrad planes changes the conformation of the G‐quadruplex, which resembles a balloon squeezed in certain directions. Such a squeezed balloon effect strengthens the G‐tetrad planes, but dislocates and weakens the loops in the G‐quadruplex upon ligand binding. These dynamic interactions indicate that the binding between the ligand and G‐quadruplex follows the induced‐fit model. We anticipate that the altered mechanical anisotropy of the ligand–G‐quadruplex complex can add additional level of regulations on the motor enzymes that process DNA or RNA molecules.
99 Luftballons: Die Bindung eines Telomestatin‐Analogons erhöht die mechanische Stabilität von G‐Tetraden, schwächt aber die von Schleifen im menschlichen telomeren G‐Quadruplex. Der mechanische Anisotropie‐Effekt wird durch die ungleichmäßige strukturelle Veränderung des G‐Quadruplexes nach Ligandenbindung aufrechterhalten, ähnlich wie wenn man einen Ballon drückt.
We aimed to compare the modified Tuck Jump Assessment (TJA) and a tri-axial accelerometer for evaluation of the efficacy of a prevention program for anterior cruciate ligament injury. Twenty-two ...female high school basketball players participated and were divided into two groups: an intervention group (n=10) and control group (n=12). The intervention group underwent an injury prevention program for 17 weeks, whereas the control group maintained a regular training routine. Each participant conducted a tuck jump test in 10 seconds while wearing a tri-axial accelerometer on their upper back. The TJA score and vertical trunk acceleration during tuck jump landing were analyzed before and after the training period. The total TJA score did not change significantly in both the intervention and control groups. Vertical trunk acceleration decreased in the intervention group (pre-test: 8.2±1.6 G, post-test: 6.7±1.0 G, p<0.001), whereas it did not change in the control group (pre-test: 7.6±2.0 G, post-test: 7.5±1.7 G, p=0.842). This short-term longitudinal study suggests that injury prevention training for junior basketball players may change their landing mechanics during a tuck jump test. Furthermore, combining TJA and a wearable sensor such as an accelerometer device may be useful to evaluate training efficacy more objectively.
Nineteen male junior football players performed the single-leg drop landing test on a force platform. The magnitude of peak vertical ground reaction force (pVGRF), time to pVGRF, loading rate, and ...center of pressure (COP) trajectory were compared between the dominant and non-dominant legs. In addition, the symmetry angle was calculated to monitor the magnitude and direction of asymmetry. The magnitude of pVGRF and the loading rate were higher in the non-dominant leg than in the dominant leg, and the time to pVGRF was shorter in the non-dominant leg than in the dominant leg. The COP trajectory length was not significantly different between the groups. In addition, the symmetry angle of the loading rate was the highest value in all variables. Therefore, high stiffness in the non-dominant leg leads to mechanical stress in the knee joint.
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