In metalorganic vapor phase epitaxy of β-Ga2O3 using triethylgallium (TEGa) and O2 as precursors and Ar as the carrier gas, the gases directly above the substrate were sampled and analyzed by ...time-of-flight mass spectrometry. TEGa was found to decompose at 400 °C–600 °C via β-hydrogen elimination reaction to generate gaseous Ga, hydrocarbons (C2H4, C2H2, C2H6), and H2. When β-Ga2O3 was grown at temperatures greater than 1000 °C and with input VI/III ratios greater than 100, the hydrocarbons and H2 were combusted and CO2 and H2O were generated. The C and H impurity concentrations measured by secondary-ion mass spectrometry in the β-Ga2O3(010) homoepitaxial layer grown under these conditions were less than their respective background levels. Thus, to grow β-Ga2O3 without C and H contamination, conditions that favor the complete combustion of hydrocarbons and H2 generated by the decomposition of TEGa should be used.
Abstract
In metalorganic vapor phase epitaxy of
β
-Ga
2
O
3
using triethylgallium (TEGa) and O
2
as precursors and Ar as the carrier gas, the gases directly above the substrate were sampled and ...analyzed by time-of-flight mass spectrometry. TEGa was found to decompose at 400 °C–600 °C via
β
-hydrogen elimination reaction to generate gaseous Ga, hydrocarbons (C
2
H
4
, C
2
H
2
, C
2
H
6
), and H
2
. When
β
-Ga
2
O
3
was grown at temperatures greater than 1000 °C and with input VI/III ratios greater than 100, the hydrocarbons and H
2
were combusted and CO
2
and H
2
O were generated. The C and H impurity concentrations measured by secondary-ion mass spectrometry in the
β
-Ga
2
O
3
(010) homoepitaxial layer grown under these conditions were less than their respective background levels. Thus, to grow
β
-Ga
2
O
3
without C and H contamination, conditions that favor the complete combustion of hydrocarbons and H
2
generated by the decomposition of TEGa should be used.
G-quadruplexes formed in the 3′ telomere overhang (~200 nucleotides) have shown to regulate biological functions of human telomeres. The mechanism governing the population pattern of multiple ...telomeric G-quadruplexes is yet to be elucidated inside the telomeric overhang in a time window shorter than thermodynamic equilibrium. Using a single-molecule force ramping assay, we quantified G-quadruplex populations in telomere overhangs in a full physiological range of 99 to 291 nucleotides. We found that G-quadruplexes randomly form in these overhangs within seconds, which leads to a population governed by a kinetic, rather than thermodynamic, folding pattern. The kinetic folding gives rise to vacant G-tracts between G-quadruplexes. By targeting these vacant G-tracts using complementary DNA fragments, we demonstrated that binding to the telomeric G-quadruplexes becomes more efficient and specific for telomestatin derivatives.
G-Quadruplex structures (G4s) in guanine-rich regions of DNA play critical roles in various biological phenomena, including replication, translation, and gene expression. The G4-forming DNAs can form ...three kinds of topologies,
i.e.
, parallel, anti-parallel, and hybrid. In this paper, we present G4 ligands L2H2-2M2EA-6OTD (
3
) and L2G2-2M2EG-6OTD (
4
) bearing tetra-aminoalkyl and -guanidinylalkyl side chains, respectively, in a macrocyclic hexaoxazole structure. These ligands efficiently induce the parallel-type topology of telomeric G4 regardless of the effects of cations. Titration with
4
results in a drastic topology switch to the parallel topology from the anti-parallel structure induced by the structurally related ligand L2H2-6OTD (
1
).
Parallel type of topology in G4 is selectively induced by tetra-guanidinylalkyl substituted 6OTD derivative.
The purpose of this study was to obtain the trunk kinematics data during a change-of-direction task and to determine the relationship between trunk kinematics and the change-of-direction performance. ...The design of this investigation was a descriptive laboratory study. Twelve healthy male collegiate soccer players (age: 21.3 ± 1.0 yrs, body mass: 67. 7 ± 6.7 kg, and height: 1.75 ± 0.05 m) participated in this study. Participants performed a shuttle run cutting task with a 180 degree pivot as quickly as possible. The shuttle run cutting time, ground contact time during a change-of-direction, and trunk inclination angle were measured. The shuttle run cutting time tends to correlate positively with ground contact time. During the change- of-direction task, the trunk forward inclination angle gradually increased during the first 50% of the stance phase and decreased subsequently whereas the trunk flexed, maintaining a left inclination during the first 40% of the stance phase and changing exponentially in the opposite direction. Forward angular displacement of the trunk between foot-contact and maximum trunk inclination correlated positively with the shuttle run cutting time (r = 0.61, p < 0.05) and ground contact time (r = 0.65, p < 0.05). These findings suggest that the change-of-direction performance could be related to the small angular displacement of the trunk during a change of direction. Moreover, it was considered that there might be optimal inclination angles related to change-of-direction performance. Therefore, coaches in field sports should check body posture and trunk movements during changes of direction. Key pointsSmall forward angular displacement of the trunk during a direction change is related to the change-of-direction performance.Trunk stability during a change of direction is an important factor in the change-of-direction performance.There might be a range of optimal angles of trunk inclination during a change of direction.Coaches in field sports should check the body posture and trunk movement of players when they require a change of direction or when they participate in sport-specific change-of-direction training.
Celotno besedilo
Dostopno za:
DOBA, FSPLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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