Publications by authors named "WK Kwok"

Effective delivery and controlled release of metallo-prodrugs with sustained activation and rapid response feed the needs of precise medicine in metal chemotherapeutics. However, gold-based anticancer drugs often suffer from detoxification binding and extracellular transfer by sulfur-containing peptides. To address this challenge, we integrate a thiol-activated prodrug strategy of newly prepared hypercoordinated carbon-centered gold(I) clusters (HCGCs) with their photosensitization character to augment the mitochondrial release of Au(I) in tumors.

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With a reliable retrospective link to early-life traumatic stress, dissociation has been formulated as a pathology of abnormal socioemotional development. Dissociation hence should be identifiable and diagnosable in childhood. This study aimed to address the extent to which current formulation and diagnostic criteria of adult dissociation is applicable to children.

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Emerging from the intricate interplay of topology and magnetism, the giant anomalous Hall effect (AHE) is the most known topological property of the recently discovered kagomé ferromagnetic Weyl semimetal CoSnS with the magnetic Co atoms arranged on a kagomé lattice. Here it is reported that the AHE in CoSnS can be fine-tuned by an applied magnetic field orientated within ≈2° of the kagomé plane, while beyond this regime, it stays unchanged. Particularly, it can vanish in magnetic fields parallel to the kagomé plane and even decrease in magnetic fields collinear with the spin direction.

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Achieving both high efficiency and high stability in blue thermally activated delayed fluorescence organic light-emitting diodes (TADF-OLEDs) is challenging for practical displays and lighting. Here, we have successfully developed a series of sky-blue to pure-blue emitting donor-acceptor (D-A) type TADF materials featuring a four-coordinated boron with 2,2'-(pyridine-2,6-diyl)diphenolate (dppy) ligands, 1-8. Synergistic engineering of substituents on the phenyl bridge as well as the electronic properties and the attached positions of heteroatom N-donors not only enables fine-tuning of the emission colors, but also modulates the nature and energies of their triplet excited states that are important for the reverse intersystem crossing (RISC).

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A new class of thermally activated delayed fluorescence (TADF) pyridine-/pyrazine-containing tetradentate C^C^N^N gold(III) complexes have been designed and synthesized. Displaying photoluminescence quantum yields (PLQYs) of up to 0.77 in solid-state thin films, these complexes showed at-least a six-fold increase in the radiative decay rate constant () in toluene upon increasing temperature from 210 to 360 K.

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Background: The immediate in-orthosis correction of adolescent idiopathic scoliosis (AIS) is a useful prognostic parameter for the long-term orthotic treatment outcome. The 3-D clinical ultrasound technique is considered a noninvasive alternative to assess scoliotic deformities that could be applied in the orthotic treatment of AIS.

Objective: This study aimed to investigate the feasibility of a purpose-design assessment frame in estimating biomechanical effects of the controlling pads of a spinal orthosis under the guidance of the ultrasound system.

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Article Synopsis
  • * Our findings show that the amount of magnetic flux entering triangular voids within the Sierpinski gaskets is related to the size of those voids, and the periodic nature of flux entry varies inversely with their size.
  • * This unique magnetic behavior could lead to the development of advanced low-loss resonators that can be adjusted for high-frequency microwave applications.
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A new class of thermally activated delayed fluorescence (TADF) tetradentate CCNN ligand-containing gold(III) complexes containing acridinyl moieties has been designed and synthesized. These complexes exhibit orange-red to deep-red emission with photoluminescence quantum yields (PLQYs) of up to 0.76 in solid-state thin films.

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Titanium nitride is a material of interest for many superconducting devices such as nanowire microwave resonators and photon detectors. Thus, controlling the growth of TiN thin films with desirable properties is of high importance. This work aims to explore effects in ion beam-assisted sputtering (IBAS), were an observed increase in nominal critical temperature and upper critical fields are in tandem with previous work on Niobium nitride (NbN).

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The recently discovered layered kagome metals of composition AV_{3}Sb_{5} (A=K, Rb, Cs) exhibit a complex interplay among superconductivity, charge density wave order, topologically nontrivial electronic band structure and geometrical frustration. Here, we probe the electronic band structure underlying these exotic correlated electronic states in CsV_{3}Sb_{5} with quantum oscillation measurements in pulsed fields up to 86 T. The high-field data reveal a sequence of magnetic breakdown orbits that allows the construction of a model for the folded Fermi surface of CsV_{3}Sb_{5}.

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Background: Patient's acceptance and compliance to spinal orthosis could influence the outcome of orthotic treatment in adolescent idiopathic scoliosis. Two innovative undergarments (thin and thick designs) were designed to improve the patient's orthosis wearing experience and acceptance.

Objective: This study aimed to evaluate the effects of patients' self-provided undergarment and 2 newly designed undergarments with respect to the orthosis wearing compliance and quality of life (QoL) measures.

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Artificial spin ices are engineered arrays of dipolarly coupled nanobar magnets. They enable direct investigations of fascinating collective phenomena from their diverse microstates. However, experimental access to ground states in the geometrically frustrated systems has proven difficult, limiting studies and applications of novel properties and functionalities from the low energy states.

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We explore spin dynamics in Cu(1,3-bdc), a quasi-2D topological magnon insulator. The results show that the thermal evolution of the Landé factor () is anisotropic: decreases while increases with increasing temperature . Moreover, the anisotropy of the factor (Δ) and the anisotropy of saturation magnetization (Δ) are correlated below 4 K, but they diverge above 4 K.

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We report three new mixed-anion two-dimensional (2D) compounds: SrFPbBiS, SrFAgBiS, and SrFBiS. Their structures as well as the parent compound SrFBiS were refined using single-crystal X-ray diffraction data, with the sequence of SrFBiS, SrFPbBiS, and SrFAgBiS defining the new homologous series SrFMBiS (M = Pb, AgBi; = 0, 1). SrFBiS has a different structure, which is modulated with a vector of 1/3* and was refined in superspace group 2/(0β0)00 as well as in the 1 × 3 × 1 superstructure with space group 2/ (with similar results).

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Article Synopsis
  • Researchers show that they can connect magnon modes from two YIG spheres using microwaves on a superconducting circuit.
  • They observe two types of interactions: coherent level repulsion and dissipative level attraction, using different types of photons.
  • This work paves the way for developing advanced magnonic networks that can improve quantum information processing technologies.
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A new class of C^C^N ligand-containing carbazolylgold(iii) dendrimers has been designed and synthesized. High photoluminescence quantum yields of up to 82% in solid-state thin films and large radiative decay rate constants in the order of 10 s are observed. These gold(iii) dendrimers are found to exhibit thermally activated delayed fluorescence (TADF), as supported by variable-temperature emission spectroscopy, time-resolved photoluminescence decay and computational studies.

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We designed and characterized a microstrip pattern of planar patch antennas compatible with a cuprate high-T superconducting terahertz emitter. Antenna parameters were optimized using an electromagnetic simulator. We observed repeatable sub-terahertz emissions from each mesa fabricated on identical BiSrCaCuO base crystals in a continuous frequency range of 0.

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A superconducting diode is an electronic device that conducts supercurrent and exhibits zero resistance primarily for one direction of applied current. Such a dissipationless diode is a desirable unit for constructing electronic circuits with ultralow power consumption. However, realizing a superconducting diode is fundamentally and technologically challenging, as it usually requires a material structure without a centre of inversion, which is scarce among superconducting materials.

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In this Letter, we describe quantitative magnetic imaging of superconducting vortices in RbEuFe_{4}As_{4} in order to investigate the unique interplay between the magnetic and superconducting sublattices. Our scanning Hall microscopy data reveal a pronounced suppression of the superfluid density near the magnetic ordering temperature in good qualitative agreement with a recently developed model describing the suppression of superconductivity by correlated magnetic fluctuations. These results indicate a pronounced exchange interaction between the superconducting and magnetic subsystems in RbEuFe_{4}As_{4}, with important implications for future investigations of physical phenomena arising from the interplay between them.

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Artificial spin ices (ASI) have been widely investigated as magnetic metamaterials with exotic properties governed by their geometries. In parallel, interest in x-ray photon orbital angular momentum (OAM) has been rapidly growing. Here we show that a square ASI with a patterned topological defect, a double edge dislocation, imparts OAM to scattered x rays.

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The drop-and-dry is a common technique allowing for creation of periodic nanoparticle (NP) structures for sensing, photonics, catalysis, etc. However, the reproducibility and scalability of this approach for fabrication of NP-based structures faces serious challenges due to the complexity of the simple, at first glance, evaporation process. In this work we study the effect of the spatial confinement on the NP self-assembly under slow solvent evaporation, when the air-liquid-substrate contact line (CL) expands from the center towards the walls of a cylindrical cell, forming a toroid.

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The ability to control the potential landscape in a medium of interacting particles could lead to intriguing collective behavior and innovative functionalities. Here, we utilize spatially reconfigurable magnetic potentials of a pinwheel artificial-spin-ice (ASI) structure to tailor the motion of superconducting vortices. The reconstituted chain structures of the magnetic charges in the pinwheel ASI and the strong interaction between magnetic charges and superconducting vortices allow significant modification of the transport properties of the underlying superconducting thin film, resulting in a reprogrammable resistance state that enables a reversible and switchable vortex Hall effect.

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Study Design: Randomized controlled trial.

Objective: To compare the effectiveness of the automated pressure-adjustable orthosis (PO) and conventional orthosis (CO) for treatment of adolescent idiopathic scoliosis (AIS).

Summary Of Background Data: Orthosis wearing quality may influence its effectiveness for AIS.

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A new class of sky-blue- to green-emitting carbazolylgold(III) C^C^N complexes containing pyrazole or benzimidazole moieties has been successfully designed and synthesized. Through the judicious choice of the N-heterocycles in the cyclometalating ligand and the tailor-made carbazole moieties, maximum photoluminescence quantum yields of 0.52 and 0.

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Article Synopsis
  • BaFMnTe is a newly discovered mixed-anion semiconductor that combines antiferromagnetism and strong red photoluminescence, making it a potential candidate for opto-spintronic applications.
  • The material is synthesized using a method called "panoramic synthesis," and it forms through a heating process that reveals a complex crystal structure and unique Mn cation ordering.
  • First-principles calculations indicate it has an indirect band gap of 1.76 eV, and time-resolved photoluminescence studies demonstrate multiple emissive states with varying lifetimes, suggesting energy transfer processes.
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