Zhong Chen

Bio: Zhong Chen is an academic researcher from Nanyang Technological University. The author has contributed to research in topics: Medicine & Chemistry. The author has an hindex of 80, co-authored 1000 publications receiving 28171 citations. Previous affiliations of Zhong Chen include Institute of High Performance Computing Singapore & National Institute of Education.

Bias-Temperature Stability of Ti–Si–N–O Films

Abstract: Copper shows a tendency to drift into contiguous dielectric material under bias and temperature stressing. The stability of different compositions (by changing silane gas flow rate) of Ti-Si-N-O films has been investigated using metal-oxide-semiconductor (MOS) capacitors. MOS samples preannealed at 250°C and subjected to bias temperature stressing (BTS) at 150°C, 200°C under an electrical field of 0.5 or 1 MV/cm show stable capacitance-voltage behavior with no flatband voltage shift from as-annealed to 90 min of BTS for Ti-Si-N-O film with Si/Ti ratio of 0.48. The lack of flatband voltage shift indicates that Ti-Si-N-O film is able to prevent Cu ion penetration. It is found that the electrical stability of Ti-Si-N-O film is reduced with higher Si/Ti ratio. For Ti-Si-N-O film with Si/Ti ratio of 0.91, flatband voltage shifts 0.75 V after 90 min of BTS at 150°C and 0.5 MV/cm, and this shift is attributed to the interface states at the Ti-Si-N-O/oxide interface that were generated during the plasma process and could not be fully healed after 250°C annealing. Thus, it is suggested that with low silane gas flow rate, an electrically stable Ti-Si-N-O film can be achieved with fewer interface states.

Water removal in MR spectroscopic imaging with L2 regularization.

Abstract: PURPOSE An L2-regularization based postprocessing method is proposed and tested for removal of residual or unsuppressed water signals in proton MR spectroscopic imaging (MRSI) data recorded from the human brain at 3T. METHODS Water signals are removed by implementation of the L2 regularization using a synthesized water-basis matrix that is orthogonal to metabolite signals of interest in the spectral dimension. Simulated spectra with variable water amplitude and in vivo brain MRSI datasets were used to demonstrate the proposed method. Results were compared with two commonly-used postprocessing methods for removing water signals. RESULTS The L2 method yielded metabolite signals that were close to true values for the simulated spectra. Residual/unsuppressed water signals in human brain short- and long-echo time MRSI datasets were efficiently removed by the proposed method allowing good quality metabolite maps to be reconstructed with minimized contamination from water signals. Significant differences of the creatine signal were observed between brain long-echo time MRSI without and with water saturation, attributable to the previously described magnetization transfer effect. CONCLUSIONS With usage of a synthesized water matrix generated based on reasonable prior knowledge about water and metabolite resonances, the L2 method is shown to be an effective way to remove water signals from MRSI of the human brain.

High-Resolution Probing of Heterogeneous Samples by Spatially Selective Pure Shift NMR Spectroscopy.

Abstract: Liquid NMR spectroscopy generally encounters two major challenges for high-resolution measurements of heterogeneous samples, namely, magnetic field inhomogeneity caused by spatial variations in magnetic susceptibility and spectral congestion induced by crowded NMR resonances. In this study, we demonstrate a spatially selective pure shift NMR approach for high-resolution probing of heterogeneous samples by suppressing effects of field inhomogeneity and J coupling simultaneously. A Fourier phase encoding strategy is proposed and implemented for spatially selective pure shift experiments to enhance signal intensity and further boost the applicability. The spatially selective pure shift method can serve as an effective tool for high-resolution probing of heterogeneous samples, thus presenting interesting prospects for extensive applications in the fields of chemistry, physics, biology, and food science.

Scratch damage resistance of silica-based sol–gel coatings on polymeric substrates

Abstract: Sol–gel coatings on polymeric substrates have been widely used in optical lenses, automobiles, safety windows, and flexible display panels. The resistance to scratch damage is an important reliability consideration. This article begins with a review of the mechanics of sliding contact, scratch failure modes and related mechanisms, and the parametric models related to these failure modes. Generally failure modes can be categorized into coating cracking driven, and delamination driven. By analyzing the potential failure modes, the importance of characterizing the coating fracture toughness and interfacial fracture toughness between the coating and the substrate is highlighted. Controlled buckling test is introduced as an easy and appropriate test method that can be used for the measurement of both properties. Silica-based sol-gel coatings with different amounts of colloidal silica were prepared on polymeric substrates. Pencil scratch test was carried out following the ISO 15184 standard. The indentation hardness, elastic modulus and fracture toughness of the coatings were also determined and correlated with the observed pencil scratch hardness. The scratch failure was found to be tensile trailing coating cracking. Analysis shows that the main factors affecting scratch resistance are elasticity modulus, thickness and fracture toughness of the coating. Based on the current and other reported results, ways to improve scratch resistance for brittle coatings on compliant substrates are discussed.

Water Splitting: One‐dimensional TiO2 Nanotube Photocatalysts for Solar Water Splitting (Adv. Sci. 1/2017)

Abstract: The rapid development of globalization and industrialization has caused a series of environment problems due to the increased consumption of fossil energy sources. To address these concerns, water splitting for hydrogen production in the presence of a semiconductor photocatalyst is studied extensively as a potential method to provide clean and renewable hydrogen source. In article 1600152, Yuekun Lai and co‐workers review various methods to construct 1D TiO2 nanotubes, and modified strategies to enhance solar light harvesting and energy conversion efficiency. Furthermore, the mechanism and applications of photo/photoelectro‐catalytic water splitting are comprehensively discussed.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Principles of Neural Science

Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...