The Experts below are selected from a list of 33 Experts worldwide ranked by ideXlab platform
Waikeung Chui - One of the best experts on this subject based on the ideXlab platform.
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fragment based approach to the design of 5 chlorouracil linked pyrazolo 1 5 a 1 3 5 triazines as thymidine phosphorylase inhibitors
European Journal of Medicinal Chemistry, 2013Co-Authors: Jiarong Li, Hriday Bera, Anton V Dolzhenko, Gigi N C Chiu, Waikeung ChuiAbstract:Abstract 5-Chlorouracil-linked-pyrazolo[1,5-a][1,3,5]triazines were designed as new thymidine phosphorylase inhibitors based on the fragment based drug design approach. Multiple-step convergent synthetic schemes were devised to generate the target compounds. The intermediate 5-chloro-6-chloromethyluracil was synthesized by a 4-step reaction. A series of the second bicyclic intermediates, namely pyrazolo[1,5-a][1,3,5]triazin-2-thioxo-4-one, was obtained from various substituted 3-aminopyrazoles. These two intermediates were coupled finally in the presence of sodium ethoxide and methanol to yield the desirable target compounds. The methylthio Coupling Spacer was found to be suitable in enabling the interaction of the two fragments at the active site and allosteric site of the enzyme. The best coupled compound (9q) inhibited the thymidine phosphorylase with an IC50 value as low as 0.36 ± 0.1 μM. In addition, 9q demonstrated a mixed-type of enzyme inhibition kinetics, thus suggesting that it might indeed potentially bind at two different sites on the enzyme.
Stuart Parkin - One of the best experts on this subject based on the ideXlab platform.
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Domain-wall velocities of up to 750 m s^−1 driven by exchange-Coupling torque in synthetic antiferromagnets
Nature Nanotechnology, 2015Co-Authors: See-hun Yang, Stuart ParkinAbstract:Racetrack memories made from synthetic antiferromagnetic structures with almost zero net magnetization allow for fast current-driven motion of domain walls. The operation of racetrack memories^ 1 , 2 , 3 is based on the motion of domain walls in atomically thin, perpendicularly magnetized nanowires, which are interfaced with adjacent metal layers with high spin–orbit Coupling. Such domain walls have a chiral Néel structure^ 4 , 5 , 6 , 7 and can be moved efficiently by electrical currents^ 5 , 6 . High-capacity racetrack memory requires closely packed domain walls, but their density is limited by dipolar Coupling from their fringing magnetic fields^ 3 . These fields can be eliminated using a synthetic antiferromagnetic structure composed of two magnetic sub-layers, exchange-coupled via an ultrathin antiferromagnetic-Coupling Spacer layer^ 8 . Here, we show that nanosecond-long current pulses can move domain walls in synthetic antiferromagnetic racetracks that have almost zero net magnetization. The domain walls can be moved even more efficiently and at much higher speeds (up to ∼750 m s^−1) compared with similar racetracks in which the sub-layers are coupled ferromagnetically. This is due to a stabilization of the Néel domain wall structure, and an exchange Coupling torque that is directly proportional to the strength of the antiferromagnetic exchange Coupling between the two sub-layers. Moreover, the dependence of the wall velocity on the magnetic field applied along the nanowire is distinct from that of the single-layer racetrack due to the exchange Coupling torque. The high domain wall velocities in racetracks that have no net magnetization allow for densely packed yet highly efficient domain-wall-based spintronics.
Jiarong Li - One of the best experts on this subject based on the ideXlab platform.
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fragment based approach to the design of 5 chlorouracil linked pyrazolo 1 5 a 1 3 5 triazines as thymidine phosphorylase inhibitors
European Journal of Medicinal Chemistry, 2013Co-Authors: Jiarong Li, Hriday Bera, Anton V Dolzhenko, Gigi N C Chiu, Waikeung ChuiAbstract:Abstract 5-Chlorouracil-linked-pyrazolo[1,5-a][1,3,5]triazines were designed as new thymidine phosphorylase inhibitors based on the fragment based drug design approach. Multiple-step convergent synthetic schemes were devised to generate the target compounds. The intermediate 5-chloro-6-chloromethyluracil was synthesized by a 4-step reaction. A series of the second bicyclic intermediates, namely pyrazolo[1,5-a][1,3,5]triazin-2-thioxo-4-one, was obtained from various substituted 3-aminopyrazoles. These two intermediates were coupled finally in the presence of sodium ethoxide and methanol to yield the desirable target compounds. The methylthio Coupling Spacer was found to be suitable in enabling the interaction of the two fragments at the active site and allosteric site of the enzyme. The best coupled compound (9q) inhibited the thymidine phosphorylase with an IC50 value as low as 0.36 ± 0.1 μM. In addition, 9q demonstrated a mixed-type of enzyme inhibition kinetics, thus suggesting that it might indeed potentially bind at two different sites on the enzyme.
See-hun Yang - One of the best experts on this subject based on the ideXlab platform.
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Domain-wall velocities of up to 750 m s^−1 driven by exchange-Coupling torque in synthetic antiferromagnets
Nature Nanotechnology, 2015Co-Authors: See-hun Yang, Stuart ParkinAbstract:Racetrack memories made from synthetic antiferromagnetic structures with almost zero net magnetization allow for fast current-driven motion of domain walls. The operation of racetrack memories^ 1 , 2 , 3 is based on the motion of domain walls in atomically thin, perpendicularly magnetized nanowires, which are interfaced with adjacent metal layers with high spin–orbit Coupling. Such domain walls have a chiral Néel structure^ 4 , 5 , 6 , 7 and can be moved efficiently by electrical currents^ 5 , 6 . High-capacity racetrack memory requires closely packed domain walls, but their density is limited by dipolar Coupling from their fringing magnetic fields^ 3 . These fields can be eliminated using a synthetic antiferromagnetic structure composed of two magnetic sub-layers, exchange-coupled via an ultrathin antiferromagnetic-Coupling Spacer layer^ 8 . Here, we show that nanosecond-long current pulses can move domain walls in synthetic antiferromagnetic racetracks that have almost zero net magnetization. The domain walls can be moved even more efficiently and at much higher speeds (up to ∼750 m s^−1) compared with similar racetracks in which the sub-layers are coupled ferromagnetically. This is due to a stabilization of the Néel domain wall structure, and an exchange Coupling torque that is directly proportional to the strength of the antiferromagnetic exchange Coupling between the two sub-layers. Moreover, the dependence of the wall velocity on the magnetic field applied along the nanowire is distinct from that of the single-layer racetrack due to the exchange Coupling torque. The high domain wall velocities in racetracks that have no net magnetization allow for densely packed yet highly efficient domain-wall-based spintronics.
Gigi N C Chiu - One of the best experts on this subject based on the ideXlab platform.
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fragment based approach to the design of 5 chlorouracil linked pyrazolo 1 5 a 1 3 5 triazines as thymidine phosphorylase inhibitors
European Journal of Medicinal Chemistry, 2013Co-Authors: Jiarong Li, Hriday Bera, Anton V Dolzhenko, Gigi N C Chiu, Waikeung ChuiAbstract:Abstract 5-Chlorouracil-linked-pyrazolo[1,5-a][1,3,5]triazines were designed as new thymidine phosphorylase inhibitors based on the fragment based drug design approach. Multiple-step convergent synthetic schemes were devised to generate the target compounds. The intermediate 5-chloro-6-chloromethyluracil was synthesized by a 4-step reaction. A series of the second bicyclic intermediates, namely pyrazolo[1,5-a][1,3,5]triazin-2-thioxo-4-one, was obtained from various substituted 3-aminopyrazoles. These two intermediates were coupled finally in the presence of sodium ethoxide and methanol to yield the desirable target compounds. The methylthio Coupling Spacer was found to be suitable in enabling the interaction of the two fragments at the active site and allosteric site of the enzyme. The best coupled compound (9q) inhibited the thymidine phosphorylase with an IC50 value as low as 0.36 ± 0.1 μM. In addition, 9q demonstrated a mixed-type of enzyme inhibition kinetics, thus suggesting that it might indeed potentially bind at two different sites on the enzyme.
