In situ, continuous monitoring of the photoinduced superhydrophilic effect: Influence of UV-type and ambient atmospheric and droplet composition

A controlled-atmosphere chamber, combined with a CCTV system, is used to monitor continuously the change in shape of water droplets on the self-cleaning commercial glass, Activ, and a sol-gel TiO2 substrate during their irradiation with either UVA or UVC light. This system allows the photoinduced superhydrophilic effect (PSH) exhibited by these materials to be studied in real time under a variety of different conditions. UVA was less effective than UVC in terms of PSH for both titania-coated glasses, and plain glass was unaffected by either form of UV irradiation and so showed no PSH activity. With UVA, ozone increased significantly the rate of PSH for both substrates, but had no effect on the wettability of plain glass. For both titania substrates and plain glass, no PSH activity was observed under an O-2-free atmosphere. A more detailed study of the PSH effect exhibited by Activ revealed that doping the water droplet with either an electron acceptor (Na2S2O8), electron donor (Na2S2O4), or simple electrolyte (KCl) in the absence of oxygen did not promote PSH. However, when Activ was UV irradiated, while immersed in a deoxygenated KCl solution, prior to testing for PSH activity, only a small change in contact angle was observed, whereas under the same conditions, but using a deoxygenated persulfate-containing immersion solution, it was rendered superhydrophilic. The correlation between organic contaminant removal and surface wetting was also investigated by using thick sol-gel films coated with stearic acid; the destruction of SA was monitored by FTIR and sudden wetting of the surface was seen to coincide with the substantial removal of the organic layer. The results of this work are discussed in the context of the current debate on the underlying cause of PSH.

Development of a dual label time-resolved fluoroimmunoassay for the detection of beta-agonists in cattle urine

beta-Agonists are among the most widely abused drugs in veterinary medicine for the illegal promotion of farm animal growth. An array of analytical procedures has been developed to detect the residues of these compounds in many biological materials. As the number of beta-agonist formulations increases, it has become increasingly difficult to devise screening techniques capable of detecting a broad spectrum of these residues in a single test. A dual immunoassay based on time-resolved fluorescence was developed that incorporated a monoclonal antibody raised to tertiary butyl amines and a polyclonal antibody to biphenolic beta-agonists. This assay was capable of detecting residues of a range of beta-agonists present in bovine urine without the need for sample extraction. The limits of detection of the assay ranged from 1 to 8.5 ng ml(-1) depending on the cross-reactivity of individual compounds with the antibodies employed in the procedure.

Perceptions and attitudes of Jordanian paediatricians towards off-label paediatric prescribing

Objective To assess current experiences and attitudes of hospital based paediatricians towards off-label medicine prescribing. Setting Paediatric hospital wards and out-patient clinics. Design A prospective, questionnaire based study. Results A 30 item questionnaire was sent to 300 hospital based paediatricians and 250 (83%) were returned completed. Over 69% of responders were familiar with the term off-label medicines. However, only 28% were knowingly prescribing off-label medicines to children. The majority of respondents (90%) expressed concerns about the safety and efficacy of off-label medicines. Only 15% had observed Adverse Drug Reactions, and 31% a treatment failure. The vast majority of respondents (83%) did not obtain informed consent or tell parents they were prescribing off label medicines to their children. Conclusions Off-label prescribing of medicines to children is a familiar concept to the majority of paediatricians in Jordan although only a smaller number are aware that it is common in their practice. Respondents showed concern about off label prescribing, although the majority do not consider it necessary to inform parents. More comprehensive research is needed in this area in Jordan and other Middle Eastern countries.

Analyzing laser plasma interferograms with a continuous wavelet transform ridge extraction technique: the method

Laser plasma interferograms are currently analyzed by extraction of the phase-shift map with fast Fourier transform (FFT) techniques [Appl. Opt. 18, 3101 (1985)]. This methodology works well when interferograms are only marginally affected by noise and reduction of fringe visibility, but it can fail to produce accurate phase-shift maps when low-quality images are dealt with. We present a novel procedure for a phase-shift map computation that makes extensive use of the ridge extraction in the continuous wavelet transform (CWT) framework. The CWT tool is flexible because of the wide adaptability of the analyzing basis, and it can be accurate because of the intrinsic noise reduction in the ridge extraction. A comparative analysis of the accuracy performances of them new tool and the FFT-based one shows that the CWT-based tool produces phase maps considerably less noisy and that it can better resolve local inhomogeneties. (C) 2001 Optical Society of America.

Label-free detection of nanomolar unmodified single- and double-stranded dna by using surface-enhanced raman spectroscopy on Ag and Au colloids

Unlabelled single- and double-stranded DNA (ssDNA and dsDNA, respectively) has been detected at concentrations =10-9?M by surface-enhanced Raman spectroscopy. Under appropriate conditions the sequences spontaneously adsorbed to the surface of both Ag and Au colloids through their nucleobases; this allowed highly reproducible spectra with good signal-to-noise ratios to be recorded on completely unmodified samples. This eliminated the need to promote absorption by introducing external linkers, such as thiols. The spectra of model ssDNA sequences contained bands of all the bases present and showed systematic changes when the overall base composition was altered. Initial tests also showed that small but reproducible changes could be detected between oligonucleotides with the same bases arranged in a different order. The spectra of five ssDNA sequences that correspond to different strains of the Escherichia coli bacterium were found to be sufficiently composition-dependent so that they could be differentiated without the need for any advanced multivariate data analysis techniques.

THE SYNTHESIS, KINETIC CHARACTERIZATION AND APPLICATION OF A NOVEL BIOTINYLATED AFFINITY LABEL FOR CATHEPSIN-B

In this study we report on the synthesis, kinetic characterization and application of a novel biotinylated and active-site-directed inactivator of cathepsin B. Thus the peptidyliazomethane biotinyl-Phe-Ala-diazomethane has been synthesized by a combination of solid-phase and solution methodologies and has been shown to be a very efficient inactivator of bovine and human cathepsin B. The respective apparent second-order rate constants (k0bs./[I]) for the inactivation of the human and bovine enzymes by this reagent, namely approximately 5.4 x 10(4) M-1 and approximately 7.8 x 10(4) M-1, compare very favourably with those values determined for the urethane-protected analogue benzloxycarbonyl-Phe-Ala-chloromethane first described by Green & Shaw [(1981) J.Biol. Chem. 256, 1923-1928], thus demonstrating that the presence of the biotin moiety at the P3 position is compatible with inhibitor effectiveness. The utilization of this reagent for the detection of cathepsin B in electrophoretic gels, using Western blotting and in combination with a streptavidin/alkaline phosphatase detection system, is also demonstrated. Given that the peptidydiazomethanes exhibit a pronounced reactivity towards cysteine proteinases, we feel that the present label may well constitute the archetypal example of a wide range of reagents for the selective labelling of this class of proteinase, even in a complex biological milieu containing additional classes of proteinases.

The Conditional Phase-type distribution: Graphical Models for Continuous Non-Normal Data:The Conditional Phase-type (C-Ph) distribution:

Conditional Gaussian (CG) distributions allow the inclusion of both discrete and continuous variables in a model assuming that the continuous variable is normally distributed. However, the CG distributions have proved to be unsuitable for survival data which tends to be highly skewed. A new method of analysis is required to take into account continuous variables which are not normally distributed. The aim of this paper is to introduce the more appropriate conditional phase-type (C-Ph) distribution for representing a continuous non-normal variable while also incorporating the causal information in the form of a Bayesian network.

Methylation using dimethylcarbonate catalysed by ionic liquids under continuous flow conditions

The ionic liquid, tributylmethylammonium methylcarbonate, has been employed as a catalytic base for clean N-methylation of indole with dimethylcarbonate. The reaction conditions were optimised under microwave heating to give 100% conversion and 100% selectivity to N-methylindole, and subsequently transferred to a high temperature/high pressure (285 degrees C/150 bar) continuous flow process using a short (3 min) residence time and 2 mol% of the catalyst to efficiently methylate a variety of different amines, phenols, thiophenols and carboxylic acid substrates. The extremely short residence times, versatility, and high selectivity have significant implications for the synthesis of a wide range of pharmaceutical intermediates, as high product throughputs can be obtained via this scalable continuous flow protocol. It has also been shown that the ionic liquid can be generated in situ from tributylamine, which has the net effect of transforming an ineffective stoichiometric base into a highly efficient catalyst for this broad class of reactions.