Investigation on nanocrystalline copper-doped zirconia thin films for optical sensing of carbon monoxide at high temperature

Nanocrystalline copper-doped zirconia (CDZ; Cu:Zr = 16:84) thin films have been synthesized on long-period fiber gratings (CDZ-LPFG) by a polymeric precursor method. The CDZ-LPFG device was demonstrated to have high sensitivity and good reversibility for low-concentration CO sensing at high temperatures. The CDZ-LPFG responds with red shifts of its resonant wavelength (λ_R) to CO-containing gases and the λ_R shift reverses when it is exposed to air. The optical response of the CDZ-LPFG to CO is due primarily to the CDZ refractive index variations resulted from the reversible redox reactions (i.e. Cu²⁺ ⇔ Cu⁺) in reducing and oxidizing atmospheres. The magnitude of the λ_R shift exhibited a strong dependence on CO concentration in a range from 0 to 1000 ppm that is potentially useful for quantitative measurement.     

Gauging the clinical significance of P-glycoprotein-mediated herb-drug interactions: comparative effects of St. John's wort, Echinacea, clarithromycin, and rifampin on digoxin pharmacokinetics

Concomitant administration of botanical supplements with drugs that are P-glycoprotein (P-gp) substrates may produce clinically significant herb-drug interactions. This study evaluated the effects of St. John's wort and Echinacea on the pharmacokinetics of digoxin, a recognized P-gp substrate. Eighteen healthy volunteers were randomly assigned to receive a standardized St. John's wort (300 mg three times daily) or Echinacea (267 mg three times daily) supplement for 14 days, followed by a 30-day washout period. Subjects were also randomized to receive rifampin (300 mg twice daily, 7 days) and clarithromycin (500 mg twice daily, 7 days) as positive controls for P-gp induction and inhibition, respectively. Digoxin (Lanoxin 0.25 mg) was administered orally before and after each supplementation and control period. Serial digoxin plasma concentrations were obtained over 24 h and analyzed by chemiluminescent immunoassay. Comparisons of area under the curve (AUC)((0-3)), AUC((0-24)), elimination half-life, and maximum serum concentration were used to assess the effects of St. John's wort, Echinacea, rifampin, and clarithromycin on digoxin disposition. St. John's wort and rifampin both produced significant reductions (p < 0.05) in AUC((0-3)), AUC((0-24)), and C(max), while clarithromycin increased these parameters significantly (p < 0.05). Echinacea supplementation did not affect digoxin pharmacokinetics. Clinically significant P-gp-mediated herb-drug interactions are more likely to occur with St. John's wort than with Echinacea.     

DNA double-strand breaks, p53, and apoptosis during lymphomagenesis in scid/scid mice

The tumor-suppressing phenotype of p53 is thought to be due to its accumulation in response to DNA damage and resultant cell cycle arrest or apoptosis. scid/scid mice are defective in DNA double-strand break repair due to a mutation in DNA-dependent protein kinase (DNAPK). Treatment of scid/scid mice with gamma radiation or N-ethyl-N-nitrosourea resulted in approximately 86% incidence of T-cell lymphomas, compared with <6% in wild-type mice. The incidence of other tumor types was not increased in scid/scid mice, suggesting that the types of DNA double-strand break that are unrepaired in these mice are not strongly carcinogenic. To determine whether mutations in DNAPK and p53 interact, we examined mice deficient in both genes. Both scid/scid p53-/- and scid/scid p53+/- mice spontaneously developed lymphomas at shorter latency than did mice with either defect alone. Loss of the wild-type p53 allele was observed in 100% of tumors from scid/scid p53 +/- mice, indicating strong selection against p53. In contrast, p53 was not inactivated in lymphomas from scid/scid p53+/+ mice. Exposure of these tumor-bearing mice to gamma radiation resulted in p53 protein accumulation and high levels of apoptosis in all tumors that were not observed in tumors from scid/scid p53+/- mice. Thus, there was a bifurcation of molecular pathways to tumorigenesis. When p53 was heterozygous in the germ line, loss of the wild-type allele occurred, and the tumors became apoptosis resistant. When p53 was wild type in the germ line, p53 was not inactivated, and the tumors remained highly apoptosis sensitive.     

Automated statistical approach to Langley evaluation for a solar radiometer

We present a statistical approach to Langley evaluation (SALE) leading to an improved method of calibration of an automated solar radiometer. Software was developed with the SALE method to first determine whether a day is a good calibration day and then to automatically calculate an intercept value for the solar radiometer. Results from manual processing of calibration data sets agree with those of the automated method to within the errors of each approach.     

Leaching characteristics of nickeliferous pyrrhotite tailings from the Sudbury,Ontario area

Mineralogical characterisation showed the deportment of Ni to be similar in the Vale and Glencore tailings, with 60% of the total Ni locked in pyrrhotite, and the balance 40% associated with pentlandite. Nickel leaching was correlated with the dissolution extents of pyrrhotite and pentlandite as functions of four leaching regimes: ‘anoxic acid’ (with and without pH control), ‘oxic acid’ (oxygen sparging), ‘oxic acid’ (air sparging), and ‘oxic ferric’ (air sparging). The results showed that the maximum Ni dissolution was obtained during the pH controlled oxic acid leach with oxygen sparging at pH 1.5, while the anoxic acid leach at pH 1.5 resulted in minimum Ni dissolution (10–15%) from pyrrhotite. An overall Ni mass balance showed that pyrrhotite and pentlandite dissolve simultaneously in the presence of Fe(III) and oxygen, in contrast to the preferential dissolution of pyrrhotite in the absence of Fe(III). Elemental sulphur yield increased with increasing temperature, but no observable trend could be linked to ferric or ferrous ion concentration.     

Accurate radiometry from space: an essential tool for climate studies

The Earth's climate is undoubtedly changing; however, the time scale, consequences and causal attribution remain the subject of significant debate and uncertainty. Detection of subtle indicators from a background of natural variability requires measurements over a time base of decades. This places severe demands on the instrumentation used, requiring measurements of sufficient accuracy and sensitivity that can allow reliable judgements to be made decades apart. The International System of Units (SI) and the network of National Metrology Institutes were developed to address such requirements. However, ensuring and maintaining SI traceability of sufficient accuracy in instruments orbiting the Earth presents a significant new challenge to the metrology community. This paper highlights some key measurands and applications driving the uncertainty demand of the climate community in the solar reflective domain, e.g. solar irradiances and reflectances/radiances of the Earth. It discusses how meeting these uncertainties facilitate significant improvement in the forecasting abilities of climate models. After discussing the current state of the art, it describes a new satellite mission, called TRUTHS, which enables, for the first time, high-accuracy SI traceability to be established in orbit. The direct use of a 'primary standard' and replication of the terrestrial traceability chain extends the SI into space, in effect realizing a 'metrology laboratory in space'.     

Microwave reflection and dielectric properties of mortar subjected to compression force and cyclically exposed to water and sodium chloride solution

Corrosion of the reinforcing steel is a major cause of damage and deterioration in reinforced concrete structures such as concrete bridge decks and columns. Chloride intrusion into concrete can lead to depassivation of the steel and initiation of corrosion. Thus, it is very important to be able to nondestructively detect and evaluate the free chloride content in concrete. Near-field microwave nondestructive testing techniques, using open-ended rectangular waveguide probes, have shown great potential for evaluating various properties of concrete, including the successful detection of sodium chloride added to mortar mixing water. In this study, several mortar samples are cyclically soaked in distilled and salt water while also experiencing compression force. Compression force, simulating in-service loading, causes microcracking, which results in increased microcracking and permeability, promoting chloride ingress. The daily microwave reflection and dielectric properties of these samples were measured at 3 GHz. The results show the capability of these microwave measurements for detecting the increased level of chloride permeation and loading as a function of the increasing number of soaking cycles. The influence of salt ingress is shown to be more prominent in the loss factor, while the effect of loading is more evident in the permittivity of the samples.