Showing papers by "Zhong Chen published in 2011"

Metabolomic Profiling of Serum from Human Pancreatic Cancer Patients Using 1H NMR Spectroscopy and Principal Component Analysis

Abstract: Pancreatic cancer is a malignant tumor with the worst prognosis among all cancers At the time of diagnosis, surgical cure is no longer a feasible option for most patients, thus early detection of pancreatic cancer is crucial for its treatment Metabolomics is a powerful new analytical approach to detect the metabolome of cells, tissue, or biofluids Here, we report the application of (1)H nuclear magnetic resonance (NMR) combined with principal components analysis to discriminate pancreatic cancer patients from healthy controls based on metabolomic profiling of the serum The metabolic analysis revealed significant lower of 3-hydroxybutyrate, 3-hydroxyisovalerate, lactate, and trimethylamine-N-oxide as well as significant higher level of isoleucine, triglyceride, leucine, and creatinine in the serum from pancreatic cancer patients compared to that of healthy controls Our data demonstrate that the subtle differences in metabolite profiles in serum of pancreatic cancer patients and that of healthy subjects as a result of physiological and pathological variations could be identified by NMR-based metabolomics and exploited as metabolic markers for the early detection of pancreatic cancer

Multifunctional Ag@Fe2O3 yolk–shell nanoparticles for simultaneous capture, kill, and removal of pathogen

Abstract: We combined silver and iron oxide nanoparticles to make unique Ag@Fe2O3 yolk–shell multifunctional nanoparticles by the Kirkendall effect. After the surface functionalization using glucose, the Ag@Fe2O3–Glu conjugates exhibited both high capture efficiency of bacteria and potent antibacterial activity. The Ag@Fe2O3 yolk–shell nanostructures may offer a unique multifunctional platform for simultaneous rapid detection and capture of bacteria and safe detoxification treatment.

In situ formation of large-scale Ag/AgCl nanoparticles on layered titanate honeycomb by gas phase reaction for visible light degradation of phenol solution

Abstract: Highly uniform AgCl nanoparticles (NPs) were grown in situ on a titanate honeycomb (THC) structure. The honeycomb structure is composed of vertically grown, intertwined one dimensional (1D) titanate nanowires from its side walls. This unique morphology of the THC surface structure was prepared by a modified hydrothermal approach within a short autoclave treatment time. The growth of AgCl crystals on the THC firstly makes use of a facile ion-exchange process by soaking the as-prepared THC in HNO 3 solution and AgNO 3 in sequence, during which Na + ion in the interlayer of titanate is consequently replaced by H + and Ag + ions without changing its morphology. The obtained Ag-THC then readily reacts with HCl vapor to form the AgCl particles on THC. Finally, the visible-light-driven plasmonic photocatalyst Ag/AgCl/THC is obtained by partially reducing Ag + ions from AgCl particles with the aid of Xe lamp illumination. The as-prepared photocatalyst exhibited high activity in the visible region of the solar spectrum for the degradation of phenol solution. The degradation performance and mechanism were discussed based on the high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC–MS).

Impact response of aluminum foam core sandwich structures

Abstract: Sandwich panels, comprised of metallic foam core and face sheets, are widely used to withstand impact and blast loadings. Based on the actual application requirements, the performance can be optimized with the proper combination of face sheets design. In this paper the impact responses of aluminum foams with various tailored face sheets, whose behavior represents elastic, elastic-ideally plastic and elastic–plastic strain work hardening, were investigated experimentally. The experiment was carried out using hemispherical indenters on blocks of aluminum foam with and without the face sheet. Competing failure modes for the initiation of failure are discussed based on comparison of energy absorption capacity. Results show that increase in thickness of foam and the use of face sheet enhances the impact energy absorption capacity. The type of face sheet not only affects the energy absorption capacity but also the failure mode for the foam blocks. Aluminum foam blocks with stainless steel sheet are strong enough to withstand the pre-designated impact loading without penetration damage. At the same time, this study also provides a comparison of the impact performance, in terms of impact energy and failure mode, among blocks with different face sheets under the low velocity impact.

Site Specific Optical and Photocatalytic Properties of Bi-Doped NaTaO3

Abstract: Synthesis, optical properties, and visible light photocatalytic activities of Bi3+-doped NaTaO3 powders have been investigated. The samples were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, diffused reflectance spectroscopy, and energy dispersive spectroscopy. It is found that the Na/Ta molar ratio of the starting materials affects the site occupancy of Bi at Na or Ta site in the lattice, and thus the optical and photocatalytic properties are significantly altered. Under Na-deficient conditions, Bi predominantly occupied Na site; the sample did not show absorption in the visible region. While under strongly Na-rich conditions, Bi occupancy at Ta site was predominant. These samples showed visible light absorption up to 450 nm. The samples prepared under mildly Na-rich condition, which leads to approximately equal occupancy of Bi at Na and Ta sites, showed visible light absorption up to 550 nm. Correspondingly, the highest photocatalytic activity for methylene blue degradation under visi...

Reconstruction of Self-Sparse 2D NMR Spectra from Undersampled Data in the Indirect Dimension

Abstract: Reducing the acquisition time for two-dimensional nuclear magnetic resonance (2D NMR) spectra is important. One way to achieve this goal is reducing the acquired data. In this paper, within the framework of compressed sensing, we proposed to undersample the data in the indirect dimension for a type of self-sparse 2D NMR spectra, that is, only a few meaningful spectral peaks occupy partial locations, while the rest of locations have very small or even no peaks. The spectrum is reconstructed by enforcing its sparsity in an identity matrix domain with lp (p = 0.5) norm optimization algorithm. Both theoretical analysis and simulation results show that the proposed method can reduce the reconstruction errors compared with the wavelet-based l1 norm optimization.

In Situ Mechanistic Investigation at the Liquid/Solid Interface by Attenuated Total Reflectance FTIR: Ethanol Photo-Oxidation over Pristine and Platinized TiO2 (P25)

Abstract: Environment and Water Industry Program Office (EWI) under the National Research Foundation of Singapore[MEWR 651/06/160]

Retinoblastoma protein is essential for early meiotic events in Arabidopsis

Abstract: We have analysed the role of RBR (retinoblastoma related), the Arabidopsis homologue of the tumour suppressor Retinoblastoma protein (pRb), during meiosis. We characterise the rbr-2 mutation, which causes a loss of RBR in male meiocytes. The rbr-2 plants exhibit strongly reduced fertility, while vegetative growth is generally unaffected. The reduced fertility is due to a meiotic defect that results in reduced chiasma formation and subsequent errors in chromosome disjunction. Immunolocalisation studies in wild-type meiocytes reveal that RBR is recruited as foci to the chromosomes during early prophase I in a DNA double-strand-break-dependent manner. In the absence of RBR, expression of several meiotic genes is reduced. The localisation of the recombinases AtRAD51 and AtDMC1 is normal. However, localisation of the MutS homologue AtMSH4 is compromised. Additionally, polymerisation of the synaptonemal complex protein AtZYP1 is abnormal. Together, these data indicate that loss of RBR during meiosis results in a reduction of crossover formation and an associated failure in chromosome synapsis. Our results indicate that RBR has an important role in meiosis affecting different aspects of this complex process.

Lithium diffusion in (Li, K, Na)NbO3 piezoeletric thin films and the resulting approach for enhanced performance properties

Abstract: Dramatic out-diffusion of lithium from (Li, K, Na)NbO3 (KNN-LN) thin films into substrate was identified as the cause of seriously degraded electrical properties. Utilizing the strong diffusion ability of lithium, lithium composition could be effectively introduced to the KNN film through the diffusion from the surface to the film. The distributions of the lithium diffused across the KNN films were found complementary to that of potassium, as lithium tended to be retained where A-site vacancies existed. With more lithium retained and reduced A-site vacancies, outstandingly large piezoelectric strain coefficient and voltage coefficient were demonstrated in the resulting Li-KNN film.

Hierarchical protonated titanate nanostructures for lithium-ion batteries

Abstract: 3D protonated titanate nanoflowers synthesized by an organic-free and cost-effective facile method exhibit a high reversible capacity, excellent cycling performance, and a remarkable rate capability when they worked as anode electrode materials for lithium-ion batteries.

High-Resolution 2D J-Resolved Spectroscopy in Inhomogeneous Fields with Two Scans

Abstract: A scheme via spatially encoded intermolecular zero-quantum coherences was proposed for high-resolution 2D J-resolved spectra in inhomogeneous fields with high acquisition efficiency. Compared to a recent paper (Pelupessy et al. Science, 2009, 324, 1693-1697), the novel method can obtain chemical shifts and J multiplicity patterns directly.

Dual‐Phase Titanate/Anatase with Nitrogen Doping for Enhanced Degradation of Organic Dye under Visible Light

Abstract: The need for environmental remediation processes on a large scale is becoming ever more urgent, especially in anticipation of the increasing demand (and potential shortage) of potable water supplies for a growing world population. Among the armory of advanced oxidation technologies (AOTs), photocatalytic (solar-light-driven) processes are particularly attractive, and photocatalysts have a well-demonstrated potential to mineralize harmful organic substances in air and water and even to act as regenerable adsorbents for toxic heavy metal ions, some of these being recovered as photodeposited metals. [1] Although anatase TiO2 remains the most popular photocatalyst due to high catalytic activity and chemical stability, there are some drawbacks associated with it. The activity is confined to UV-light stimulation, representing just a few percent of the solar-power spectrum. In this respect, much research has been done in modifying the bandgap of the material to extend the absorption into the visible-light region. [2] In addition, the adsorptive properties of TiO2 are not ideal either. [3] Since photoreactions take place at or near the catalyst surface, surface adsorption is critical for efficient interfacial charge transfer to and from the target molecules. In contrast, titanate materials have recently been identified as superior adsorbents for, for example, organic dyes and heavy metal ions. [4] The crystal structure consists of layers of TiO6 octahedra in edge connectivity with protons or alkali metal ions localized between the layers. [5] Various one-dimensional structures, including nano

Interdependent Intermetallic Compound Growth in an Electroless Ni-P/Sn-3.5Ag Reaction Couple

Abstract: The interfacial microstructure of electroless Ni-P/Sn-3.5Ag solder joints was investigated after reflow and high-temperature solid-state aging to understand its interdependent growth mechanism and related kinetics of intermetallic compounds (IMCs) at the interface. The reflow and aging results showed that mainly three IMC layers, Ni3Sn4 ,N i 2SnP, and Ni3P, formed during the soldering reaction. It was found that the Ni3Sn4 and Ni3P layers grow predominantly as long as the electroless Ni-P layer is present; however, once the Ni-P layer is fully consumed, the Ni2SnP layer grows rapidly at the expense of the Ni3P layer. A transition in the Ni3Sn4 morphology from needle and chunky shape to scallop shape was observed after the solid-state aging of reflowed samples. The kinetics data obtained from the growth of compound layers in the aged samples revealed that initially the growth of the Ni2SnP layer is controlled by diffusion, and subsequently by the rate of reaction after the Ni-P metallization is fully consumed. It was found that complete transformation of the electroless Ni-P layer into a Ni3P layer results in the rapid growth of the Ni2SnP layer due to the dominating reaction of Sn with Ni3P. The apparent activation energies for the growth of Ni3Sn4 ,N i 2SnP, and Ni3P compound layers were found to be 98.9 kJ/mol, 42.2 kJ/mol, and 94.3 kJ/mol, respectively.

Multi-functional hybrid protonated titanate nanobelts with tunable wettability

Abstract: We present the preparation of millimetre-sized liquid marbles with strong mechanical strength and good deformability using self-assembled fluoroalkylsilane functionalized titanate nanobelt powder. The strength and deformability of the marbles are adjustable by changing the intrinsic wetting state of the titanate nanoparticles. The excellent chemical stability of surface layer on the liquid marbles consisting of the titanate nanobelts provides the possibility for qualitative and quantitative chemical sensing under a wide range of pH values.

The formation of micrometer-long TiO 2 nanotube arrays by anodization of titanium film on conducting glass substrate

Abstract: Micrometer-long titanium oxide nanotube arrays, tens of nanometers in diameter, were fabricated by anodization of titanium film coated on a conducting glass substrate. The Ti film was deposited by magnetron sputtering at room temperature. The effect of anodizing conditions on the formation of TiO2 nanotubes was investigated. The results indicate that dense and uniform Ti film deposited under 150 W at room temperature was favorable for the formation of ordered nanotube arrays. The average diameter of the TiO2 nanotubes varied from 35 to 95 nm when the anodization potential changed from 10 to 40 V. Micrometer-long nanotubes (1.1 μm) with good adhesion to the substrate could be obtained in 0.5 wt% NH4F/glycerol at 30 V for 2 h. After heat treatment, the crystalline anatase nanotubes show enhanced photoelectrochemical activity compared with those anodized in 1 M H3PO4/0.5 wt% HF. This is attributed to the increased light-harvesting abilities.

Effect of sulfur impurity on the stability of cubic zirconia and its interfaces with metals

Abstract: Based on the density functional theory (DFT), we evaluate the effect of sulfur impurity on the stability of cubic zirconia (c-ZrO2) and its interfaces with metals (Ni, Cu). It is observed that, at low concentration, sulfur atoms have the tendency to locate at the zirconia surface, while at high concentration (∼23.0 wt%), homogeneous ZrOS structure can be obtained. We further predict that sulfur impurity in c-ZrO2 induces a reduction of the wettability between metals (Cu, Ni) and c-ZrO2. Thus, for Cu(011)/ZrO2(011) and Ni(011)/ZrO2(011) interfaces, the predicted reductions of the work of separations are up to 53%. This may have significant effect on the degradation of solid oxide fuel cell (SOFC) performance, when sulfur-containing fuels are used. The computational schemes developed in this study are useful for the search for more sulfur-tolerant metal/ceramic anode systems.

Effect of ultrasonic energy on nanoscale interfacial structure in copper wire bonding on aluminium pads

Abstract: The effect of ultrasonic vibration on nanoscale interfacial structure of thermosonic copper wire bonding on aluminium pads was investigated. It was found that bonding strength was determined by the extent of fragmentation of a native aluminium oxide overlayer (5–10 nm thick) on aluminium pads, forming paths for formation of intermetallic compound CuAl2 in areas of direct contact of bonded metal surfaces. The degree of fracture of the oxide layer was strongly affected by a level of ultrasonic power.