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.

Preparation of magnetically recoverable bentonite-Fe3O4-MnO2 composite particles for Cd(II) removal from aqueous solutions.

Abstract: In this study, bentonite–Fe3O4–MnO2 composite was synthesized by combining bentonite with Fe3O4 and MnO2 through co-precipitation. Vibrating-sample magnetometry, scanning electron microscopy with energy-dispersive X-ray spectrometry, transmission electron microscopy, Brunauer–Emmett–Teller measurements, and X-ray powder diffraction techniques were used to characterize the composite. The composite consists of Fe3O4 nanoparticles orderly assembled on the surface of bentonite and an outer layer of MnO2 sheets. The composite’s particles possess a saturation magnetization of 13.4–30.5 emu/g and a high specific surface area (203.89 m2/g). The adsorption behaviors of the composite in Cd(II) removal were evaluated by batch equilibrium experiments. Kinetic and isothermal data fit well the pseudo-second-order and the Freundlich models, respectively. Adsorption reached equilibrium within 30 min, and the Freundlich capacity of the composite was 35.35 mg/g. The adsorption capacity of Cd(II) increased with increasing pH and was dependent on the ionic strength. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy showed the combination of surface hydroxyl groups of the composite and Cd(II) in the solution. The prepared composite can be easily recycled and reused by taking advantage of its magnetic properties. The results show that the designed composite is a promising absorbent for the treatment of Cd-contaminated water.

Mechanistic investigations of photo-driven processes over TiO2 by in-situ DRIFTS-MS: Part 1. Platinization and methanol reforming

Abstract: There is growing interest in the reforming of methanol and other bio-oxygenates as high-density, CO2-neutral, renewable sources of H2. Photocatalysis is worthy of investigation as a potentially economic means to drive such endothermic processes. In this study, in-situ DRIFTS, adapted for optical pumping and coupled to on-line MS, was used to observe the surface of TiO2 (Degussa P25) during photo-metallization from pre-sorbed hexachloroplatinate, at a nominal Pt loading of 1 wt%, and to evaluate photo-reforming of methanol over the resulting Pt/TiO2 composite. The irreversible growth of a quasi-continuum absorption, characteristic of the surface plasmon resonance of zerovalent Pt nanoparticles, along with bands at 2050 and 1830 cm−1 typical of metal-adsorbed CO, indicated that photo-metallization was complete typically within 2 hours. Methanol reforming was photocatalyzed at room temperature but in low quantum efficiency, ϕ ≈ 0.01. However, this was raised substantially, to ϕ ≈ 0.07, simply by the application of mild heating (T ≤ 70 °C). Photo-reforming proceeded at a fixed rate but the H2/CO2 ratio generally exceeded that of the reforming stoichiometry, suggesting some retention of CO2. The photo/thermal synergy was rationalized by model DRIFTS studies, starting from formalin (hydrated formaldehyde), which revealed key features of the mechanism. TiO2 promoted the Cannizzaro disproportionation in the dark, yielding formate and methoxy species already at 40 °C. While methoxy was effectively cycled back to the initial photo-dehydrogenation stage, the slow step was identified as formate decomposition to H2 and CO2. The low value measured for the apparent activation energy (∼40 kJ mol−1) was taken as supporting evidence for ‘water-assisted destabilization’ of formate, as originally reported by Shido and Iwasawa. No evidence was found for an alternative thermal- or photo-reforming mechanism involving the Pt–COad species.

Bouncing dynamics of impact droplets on the convex superhydrophobic surfaces

Abstract: Bouncing dynamics of impact droplets on solid surfaces intensively appeal to researchers due to the importance in many industrial fields. Here, we found that droplets impacting onto dome convex superhydrophobic surfaces could rapidly bounce off with a 28.5% reduction in the contact time, compared with that on flat superhydrophobic surfaces. This is mainly determined by the retracting process of impact droplets. Under the action of dome convexity, the impact droplet gradually evolves into an annulus shape with a special hydrodynamic distribution. As a consequence, both the inner and external rims of the annulus shape droplet possess a higher retracting velocity under the actions of the inertia force and the surface energy change, respectively. Also, the numerical simulation provides a quantitative evidence to further verify the interpretation on the regimes behind the rapidly detached phenomenon of impact droplets.

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...