Wei-Ning Wang

Size and Structure Matter: Enhanced CO2 Photoreduction Efficiency by Size-Resolved Ultrafine Pt Nanoparticles on TiO2 Single Crystals

A facile development of highly efficient Pt-TiO(2) nanostructured films via versatile gas-phase deposition methods is described. The films have a unique one-dimensional (1D) structure of TiO(2) single crystals coated with ultrafine Pt nanoparticles (NPs, 0.5-2 nm) and exhibit extremely high CO(2) photoreduction efficiency with selective formation of methane (the maximum CH(4) yield of 1361 μmol/g-cat/h). The fast electron-transfer rate in TiO(2) single crystals and the efficient electron-hole separation by the Pt NPs were the main reasons attributable for the enhancement, where the size of the Pt NPs and the unique 1D structure of TiO(2) single crystals played an important role.

Gene expression profiles in rat lung after inhalation exposure to C60 fullerene particles.

Concern over the influence of nanoparticles on human health has risen due to advances in the development of nanotechnology. We are interested in the influence of nanoparticles on the pulmonary system at a molecular level. In this study, gene expression profiling of the rat lung after whole-body inhalation exposure to C(60) fullerene (0.12mg/m(3); 4.1x10(4) particles/cm(3), 96nm diameter) and ultrafine nickel oxide (Uf-NiO) particles (0.2mg/m(3); 9.2x10(4) particles/cm(3), 59nm diameter) as a positive control were employed to gain insights into these molecular events. In response to C(60) fullerene exposure for 6h a day, for 4 weeks (5 days a week), C(60) fullerene particles were located in alveolar epithelial cells at 3 days post-exposure and engulfed by macrophages at both 3 days and 1 month post-exposures. Gene expression profiles revealed that few genes involved in the inflammatory response, oxidative stress, apoptosis, and metalloendopeptidase activity were up-regulated at both 3 days and 1 month post-exposure. Only some genes associated with the immune system process, including major histocompatibility complex (MHC)-mediated immunity were up-regulated. These results were significantly different from those of Uf-NiO particles which induced high expression of genes associated with chemokines, oxidative stress, and matrix metalloproteinase 12 (Mmp12), suggesting that Uf-NiO particles lead to acute inflammation for the inhalation exposure period, and the damaged tissues were repaired in the post-exposure period. We suggest that C(60) fullerene might not have a severe pulmonary toxicity under the inhalation exposure condition.

Novel rare-earth-free tunable-color-emitting BCNO phosphors

We present a facile synthesis of novel, rare-earth (RE)-ion-free boron carbon oxynitride (BCNO) phosphors. The preparation method, chemical composition, luminescent properties and emission mechanisms, as well as current trends in BCNO phosphors are reviewed. The novel BCNO phosphors were synthesized from inexpensive and environmentally friendly raw materials by a straightforward route using liquid precursors at low temperatures under atmospheric pressure. The newly developed BCNO phosphors demonstrated tunable color emission, high quantum efficiency, and long-duration afterglow. The color emission of these phosphors can be tuned across almost the entire visible light spectrum by varying the molar ratios of the raw materials.

Pulmonary toxicity of well-dispersed multi-wall carbon nanotubes following inhalation and intratracheal instillation

Abstract Multi-walled carbon nanotubes (MWCNTs), dispersed in suspensions consisting mainly of individual tubes, were used for intratracheal instillation and inhalation studies. Rats intratracheally received a dose of 0.2 mg, or 1 mg of MWCNTs and were sacrificed from 3 days to 6 months. MWCNTs induced a pulmonary inflammation, as evidenced by a transient neutrophil response in the low-dose groups, and presence of small granulomatous lesion and persistent neutrophil infiltration in the high-dose groups. In the inhalation study, rats were exposed to 0.37 mg/m3 aerosols of well-dispersed MWCNTs (>70% of MWCNTs were individual fibers) for 4 weeks, and were sacrificed at 3 days, 1 month, and 3 months after the end of exposure. The inhalation exposures delivered less amounts of MWCNTs into the lungs, and therefore less pulmonary inflammation responses was observed, as compared to intratracheal instillation. The results of our study show that well-dispersed MWCNT can produce pulmonary lesions, including inflammation.

Rapid synthesis of nanostructured Cu–TiO2–SiO2 composites for CO2 photoreduction by evaporation driven self-assembly

Nanostructured copper doped titania–silica (Cu–TiO2–SiO2) photocatalyst composite particles were directly formed in a rapid manner by evaporation driven self-assembly of nanocolloids in a furnace aerosol reactor (FuAR). Aqueous suspensions of nanosized TiO2 and SiO2 colloids and copper nitrate solution were used as precursors. The size, composition, and porosity of the composite particles were tailored by manipulating the precursor concentration, stoichiometric ratio, and synthesis temperature, respectively. The as-prepared composite particles were characterized by means of SEM, TEM, XRD, UV-VIS, and nitrogen physisorption measurements, to determine particle diameter, morphology, crystallinity, absorption band, surface area, and pore size. CO2 photoreduction was conducted inside a quartz reactor under illumination of UV light followed by GC analysis. The results revealed that the composite particles were submicrometre-sized mesoporous spheres with average pore sizes of 20 to 30 nm, having optimal molar percentages of TiO2 and Cu to the whole particle of 2% and 0.01%, respectively, achieving a relatively high CO2 conversion efficiency, i.e. a CO yield of approximately 20 μmol/g TiO2/h.

Overweight, obesity and thyroid cancer risk: a meta-analysis of cohort studies.

Objective: This meta-analysis examined the relationship between excess body weight or body mass index (BMI) and risk of thyroid cancer. METHODS: PubMed®, MEDLINE®, EMBASE™ and Academic Search™ Premier databases were searched to identify cohort studies examining the effect of being overweight or obese on the risk of thyroid cancer. RESULTS: The inclusion criteria were met by seven cohort studies (total number of thyroid cancer cases, 5154). The pooled relative risk (RR) of thyroid cancer was 1.13 (95% confidence interval [CI] 1.04, 1.22) for overweight. Obesity was also linked with increased thyroid cancer risk in males and females, the strength of the association increasing with increasing BMI. The combined RR of thyroid cancer was 1.18 (95% CI 1.11, 1.25) for excess body weight (overweight and obesity combined). Being overweight was associated with a significant increase in thyroid cancer risk among non-Asians, but not among Asians. Overweight, obesity and excess body weight were all associated with papillary thyroid carcinoma risk. CONCLUSIONS: The association between overweight/ obesity/excess body weight and thyroid cancer risk was confirmed.

Nanofiltration of l-phenylalanine and l-aspartic acid aqueous solutions

Abstract The permeation experiments of l -phenylalanine ( l -Phe) and l -aspartic acid ( l -Asp) aqueous solutions were carried out with two commercial nanofiltration (NF) membranes, ESNA2 membrane and ES20 membrane. The rejections to l -Phe and l -Asp by ESNA2 membrane are about 0 and 90%, respectively, at the pH value ranging from 4 to 9, while the rejections to l -Phe and l -Asp by ES20 membrane are almost 100% irrespective of pH value. The results show that these two NF membranes are possible to concentrate and separate l -Phe and l -Asp effectively by choosing proper condition such as the pH value of solution. Based on the experimental results, a simple batch-wise NF process system was design for concentration and diafiltration of virtual l -Phe enzymatic reaction solution with some l -Asp. The simulation results show that it is feasible to separate l -Phe and l -Asp in viewpoint of technology.

Evaporation-Induced Crumpling of Graphene Oxide Nanosheets in Aerosolized Droplets: Confinement Force Relationship.

A possible solution to solve the restacking issue of graphene oxide (GO) nanosheets during large-scale production is to turn the two-dimensional (2D) nanosheets into three-dimensional (3D) crumpled balls that have excellent compressive properties but still maintain high free volumes. An aerosol-based process has been proven to be a rational method for this purpose, in which, the crumpling phenomenon, however, has hitherto remained unclear. Here we present a detailed understanding of the crumpling of GO nanosheets by a systematic investigation conducted in aerosolized droplets by means of in-line (e.g., scanning mobility particle sizer) and off-line (e.g., electron microscopy) measurements. Correlations between the confinement force and various parameters, such as evaporation rate and precursor concentration were established to derive a universally applicable equation. Both calculation and experimental results revealed that the evaporation rate plays an important role in controlling the crumpling process.

Experimental investigation on separation performance of nanofiltration membranes for inorganic electrolyte solutions

Abstract Permeation experiments of KCl, NaCl, LiCl, MgCl2, MgSO4 and K2SO4 solutions were carried out using two commercial nanofiltration membranes, which were NF45 (Dow Chemical Corporation) and SU200 (Toray Corporation) membranes. The effects of the type and the concentration of electrolytes as well as the pH value of the electrolyte solution on the separation performance (such as rejections) were investigated. The experimental results showed that NF45 and SU200 membranes possess similar separation potential to the inorganic electrolytes of 1-1 type (LiCl, NaCl and KCl) and much different ones to the other electrolytes containing bivalent ions (MgCl2, K2SO4 and MgSO4) with different concentrations. The rejections to inorganic electrolytes by the two NF membranes declined with the growth of the electrolyte concentrations and approached some certain values when on much high concentrations (more than 400 mol·m−3), which implied that the size of electrolyte-ions could not be ignored by comparison to the pore radii of NF membranes. The two NF membranes behave almost the same rejections to the electrolytes such as LiCl under various pH values of the feed solution from pH=4 to 10 and behaved the similar minimum values near the isoelectric point of pH=6.5.

Inflammogenic effect of well-characterized fullerenes in inhalation and intratracheal instillation studies

BackgroundWe used fullerenes, whose dispersion at the nano-level was stabilized by grinding in nitrogen gas in an agitation mill, to conduct an intratracheal instillation study and an inhalation exposure study. Fullerenes were individually dispersed in distilled water including 0.1% Tween 80, and the diameter of the fullerenes was 33 nm. These suspensions were directly injected as a solution in the intratracheal instillation study. The reference material was nickel oxide in distilled water. Wistar male rats intratracheally received a dose of 0.1 mg, 0.2 mg, or 1 mg of fullerenes and were sacrificed after 3 days, 1 week, 1 month, 3 months, and 6 months. In the inhalation study, Wistar rats were exposed to fullerene agglomerates (diameter: 96 ± 5 nm; 0.12 ± 0.03 mg/m3; 6 hours/days for 5 days/week) for 4 weeks and were sacrificed at 3 days, 1 month, and 3 months after the end of exposure. The inflammatory responses and gene expression of cytokine-induced neutrophil chemoattractants (CINCs) were examined in rat lungs in both studies.ResultsIn the intratracheal instillation study, both the 0.1 mg and 0.2 mg fullerene groups did not show a significant increase of the total cell and neutrophil count in BALF or in the expression of CINC-1,-2αβ and-3 in the lung, while the high-dose, 1 mg group only showed a transient significant increase of neutrophils and expression of CINC-1,-2αβ and -3. In the inhalation study, there were no increases of total cell and neutrophil count in BALF, CINC-1,-2αβ and-3 in the fullerene group.ConclusionThese data in intratracheal instillation and inhalation studies suggested that well-dispersed fullerenes do not have strong potential of neutrophil inflammation.