Toxigenic Clostridium difficile (C. difficile) carriers represent an important source in the transmission of C. difficile infection (CDI) during hospitalisation, but its prevalence and mode in patients with hepatic cirrhosis are not well established. We investigated longitudinal changes in carriage rates and strain types of toxigenic C. difficile from admission to discharge among hepatic cirrhosis patients. Toxigenic C. difficile was detected in 104 (19.8%) of 526 hepatic cirrhosis patients on admission, and the carriage status changed in a portion of patients during hospitalisation. Approximately 56% (58/104) of patients lost the colonisation during their hospital stay. Among the remaining 48 patients who remained positive for toxigenic C. difficile, the numbers of patients who were positive at one, two, three and four isolations were 10 (55.6%), three (16.7%), two (11.1%) and three (16.7%), respectively. Twenty-eight patients retained a particular monophyletic strain at multiple isolations. The genotype most frequently identified was the same as that frequently identified in symptomatic CDI patients. A total of 25% (26/104) of patients were diagnosed with CDI during their hospital stay. Conclusions: Colonisation with toxigenic C. difficile strains occurs frequently in cirrhosis patients and is a risk factor for CDI.

Novel plate-stratiform nanostructured Bi12O17Cl2 was studied with its visible-light photocatalytic performance. The Bi12O17Cl2 photocatalyst synthesized by a solid-state reaction was constructed of dozens of primary nanosheets, which were stacked by a parallel array of ultrathin secondary nanosheets. The microstructure and crystal structure of Bi12O17Cl2 primary and secondary nanosheets were discovered by high-resolution transmission electron microscopy and selected-area electron diffraction analyses. Its absorption edge was determined as about 590 nm and the band gap energy was 2.1 eV. The Bi12O17Cl2 nanomaterial exhibited superior visible-light-responsive photocatalytic activity and confirmed successful photodegradation of methyl orange (MO) under visible-light irradiation. The degradation efficiency was up to 97% in 90 min. Furthermore, the Bi12O17Cl2 photocatalyst exhibited excellent photostability and high mineralization capacity for MO photodegradation reaction. The MO photodegradation process was dominated by the direct photocatalytic mechanism. The contribution from its morphology and microstructure to superior photocatalytic activity was discussed.

Due to the potential applications to high-efficiency and light-weight solar cells, the growth of CuInGaSe2 (CIGS) nanoparticles is a recent research focus. We have developed a relatively simple solvothermal route to grow high quality CIGS nanoparticles in an autoclave under different temperatures (170 – 280°C). The effect of reaction temperature on the shape of CIGS nanoparticles has been investigated. At lower temperatures, the CIGS particles show plate-like shape. Whereas at higher temperatures, most of them exhibit rod-like feature. The nanoparticle products have been also characterized by field emission scanning electron microscopy and X-ray diffraction techniques.

A solution-processed method is developed to fabricate fully transparent resistive random access memory (RRAM) devices with a configuration of FTO/ZrO2/ITO, where the zirconium dioxide (ZrO2) layer was firstly deposited on fluorine tin oxide (FTO) substrate by sol-gel and then indium tin oxide (ITO) films were deposited on ZrO2 layer by sol-gel as the top electrodes.The solution processed FTO/ZrO2/ITO based RRAM devices show the fully transparency and excellent bipolar resistance switching behaviors. The resistance ratio between high and low resistance states was more than 10, and more than 100 switching cycles and good data retention and multilevel resistive switching have been demonstrated.

In this work, we employed three different methods to fabricate solar cell structures on indium tin oxide (ITO) substrates. For the first method, multi-layered structures were prepared by using single walled carbon nanotubes (SWCNTs) and tin oxide (SnO2). First, a SWCNT layer was deposited on the ITO substrate; and photoactive material was then coated on the top of the SWCNT layer. For the second method, photoactive particles were added to a solution of SWCNTs. The SWCNT/SnO2 solution was mechanically stirred and then deposited on the ITO substrate. For the third method, we synthesized photoactive particles on SWCNTs through a chemical-solution routine using SnCl4 as a precursor. We characterized the morphology and structure of the SWCNTs coated with SnO2 nanoparticles prepared with the three different methods by using a field emission scanning electron microscope equipped with an X-ray energy dispersive spectrometer. We characterized the photoelectrochemical properties of all electrodes by using an electrochemical station; mainly, we examined the photocurrent generated under periodic illumination. Our results indicate that there are significant differences in the photocurrent in the presence of SWCNTs. We propose the following hypothetical mechanism: without carbon nanotubes, generated electrons (when light is absorbed by SnO2 particles) must cross the particle network to reach an electrode. Many electrons never escape this network to generate an electrical current. The carbon nanotubes “collect” the electrons and provide, therefore, a more direct route to the electrode, thus improving the efficiency of the solar cells.

In this work, Pt and Pt-Ru nanoparticles were synthesized on both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). Effects of different nanotube supports on electrocatalytic activity of Pt and Pt-Ru nanoparticles for methanol and ethanol oxidations were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. In comparison to MWCNTs, SWCNT supported Pt and Pt-Ru catalysts demonstrate better electrocatalytic activities in terms of forward peak current density, the ratio of forward peak current density to reverse peak current density, and charge transfer resistance. This study indicates that SWCNTs can serve as effective catalyst supports for both direct methanol and ethanol fuel cells.

In this article, two simple methods, evaporation-condensation and catalytic thermal evaporation, were used to investigate the synthesis of CdS nanostructures for nanoscale optoelectronic applications. To understand their growth mechanisms, various electron microscopy and microanalysis techniques were utilized in characterizing their morphologies, internal structures, growth directions and elemental compositions. The electron microscopy study reveals that when using the evaporation-condensation method, branched CdS nanorods and self-assembled arrays of CdS nanorods were synthesized at 800°C and 1000°C, respectively. Instead of morphological differences, both types of CdS nanorods grew along the [0001] direction. However, when using the catalytic thermal evaporation method (Au as the catalyst), patterned CdS nanowires and nanobelts were formed at the temperature region of 500–600°C and 600–750°C, respectively. Their growth direction was along the direction [1010] instead of [0001]. Based on the microscopy and microanalysis results, we propose some growth mechanisms in relation to the growth processes of those exotic CdS nanostructures.

Two fabrication methods have been investigated to synthesize silicon oxide nanowires. One was catalytic thermal evaporation method in which silicon monoxide was used as the precursor and Au particles served as the catalysts. Using nanosphere lithography, patterned nanowires were obtained and their growth positions were controlled by the locations of Au catalysts. For the second method, without silicon monoxide as the precursor and without the aid of Au catalyst, silicon oxide nanowires directly formed along the <110> direction of the silicon substrate only with the introduction of hydrogen gas. A series of experiments were carried out to study effects of reaction time, temperature, and hydrogen on the growth of the nanowires. Also, various electron microscopy techniques were utilized to characterize their morphologies and internal structures and to analyze their compositional distributions. In this paper, the characterization of different silicon oxide nanowires and their formation mechanisms in relation to both preparation methods are discussed.

We recently developed a novel floating-potential dielectrophoretic method to selectively position individual single-walled carbon nanotubes between two floating electrodes while the bundles of nanotubes and impurities were attracted into the region between two control electrodes. In this study, we investigated effects of several process parameters including electric field distribution, electric field frequency, and solution media in order to understand the physical mechanisms of this dielectrophoretic process and to improve its efficiency. Results showed that both the magnitude and the direction of electrical force applied onto the nanotubes can be tailored by changing these process parameters. It was found that a 1 wt% sodium dodecyl sulfate in deionized water is an efficient solution for separating bundles of nanotubes into individual nanotubes and aligning individual nanotubes with a clean surface between two electrical contacts in comparison to N,N-dimethylformamide, 1,2-dichloroethane, 1,2-dichlorobenzene, 1,1-dichloromethane, ethanol, and isopropanol solutions. The fabricated carbon nanotube devices exhibit electronic properties comparable to nanotube transistors and interconnects fabricated by other methods.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Atomically resolved images of single-wall carbon nanotubes (CNT) grown in a chemical vapor deposition (CVD) chamber were obtained with the scanning tunneling microscope (STM) under ambient conditions. We found that the average diameters d of the CVD-grown CNTs appear to fall into a bimodal distribution of 1.0 and 0.6 nm, and the chiral angle Ø was observed to be close to zero degree. The summation of the lattice indices (n+m) was determined to be 14 and 9 for d= 1.0nm and d= 0.6nm, respectively. The most possible lattice index pairs (n, m) with a chiral angle close to zero degree are (7, 7) and (5, 4), which indicates that the larger nanotubes are metallic and the smaller nanotubes are semi-conductive.