Determination of the Aspect-ratio Distribution of Gold Nanorods in a Colloidal Solution using UV-visible absorption spectroscopy.

Knowledge of the distribution of the aspect ratios (ARs) in a chemically-synthesized colloidal solution of Gold Nano Rods (GNRs) is an important measure in determining the quality of synthesis, and consequently the performance of the GNRs generated for various applications. In this work, an algorithm has been developed based on the Bellman Principle of Optimality to readily determine the AR distribution of synthesized GNRs in colloidal solutions. This is achieved by theoretically fitting the longitudinal plasmon resonance of GNRs obtained by UV-visible spectroscopy. The AR distribution obtained from the use of the algorithm developed have shown good agreement with those theoretically generated one as well as with the previously reported results. After bench-marking, the algorithm has been applied to determine the mean and standard deviation of the AR distribution of two GNRs solutions synthesized and examined in this work. The comparison with experimentally derived results from the use of expensive Transmission Electron Microscopic images and Dynamic Light Scattering technique shows that the algorithm developed offers a fast and thus potentially cost-effective solution to determine the quality of the synthesized GNRs specifically needed for many potential applications for the advanced sensor systems.

A Turn-On Fluorescence-Based Fibre Optic Sensor for the Detection of Mercury.

The design, development, and evaluation of an optical fibre sensor for the detection of Hg2+ in aqueous media are discussed in detail in this paper. A novel fluorescent polymeric material for Hg2+ detection, based on a coumarin derivative (acting as the fluorophore) and an azathia crown ether moiety (acting as the mercury ion receptor), has been synthesized. The fluorophore was covalently immobilized onto the fibre surface by polymerisation using the ion imprinting technique and exhibited a significant increase in fluorescence intensity in response to Hg2+ via a photoinduced electron transfer (PET) mechanism. The sensor provided a response over a concentration range of 0-28 µM with an acceptable response rate of around 11 min and a recovery rate of around 30 min in a Tris-EDTA buffer solution. A detection limit of 0.15 µM was obtained with a possibility of improvement by changing the thickness of the polymer layer and using a more sensitive detector. High-quality performance is seen through a high selectivity for Hg2+ over other metal ions, excellent photo-stability and reversibility which was also demonstrated, making this type of sensor potentially well suited for in-situ monitoring of mercury in the environment.

Fluorescent imprinted polymer sensors for chiral amines.

Molecularly imprinted polymer (MIP) based fluorescent sensors require suitable fluorescent moieties which respond to the binding event with significant fluorescence changes. Two novel polymerisable coumarins: 6-styrylcoumarin-4-carboxylic acid (SCC) and 6-vinylcoumarin-4-carboxylic acid (VCC) have been designed and synthesised. These functional monomers allow for the preparation of fluorescent sensors of chiral amines, an important class of pharmaceutical compounds. MIPs were prepared with SCC and VCC, using (-)-ephedrine as a template and ethylene glycol dimethacrylate as a cross-linker. In MeCN, the polymers exhibited a decrease of fluorescence in response to amines, with some selectivity for the template over its enantiomer (+)-ephedrine and other structural analogues. Interestingly the response of SCC to (-)-ephedrine in the MIP occurs in the opposite direction to the change when recognition occurs in solution. The control polymers (NIPs) exhibited a lesser response to (-)-ephedrine, and no resolving power, suggesting that imprinting has been successful and selective recognition sites exist in the MIPs. Recognition in aqueous buffers at different pHs has also been investigated.

Combined ipsilateral treatment of cervical lymph nodes metastases from an unknown primary.

INTRODUCTION: The management of squamous cell carcinoma in undetermined primary tumours in the head and neck region (approximately 5.5% of patients) is controversial. MATERIAL AND METHODS: The present report examines the outcomes for 14 patients after an initial treatment strategy directed principally at the side of the neck that is clinically involved. The distribution of nodal status was as follows: 1 N1, 8 N2A, 4 N2B, and 1 N3. RESULTS: Initial treatment included a modified neck dissection in 12 cases and radical neck dissection in 2 cases, plus postoperative radiation in 10 cases. Radiotherapy was directed at the ipsilateral side of the neck alone. Concomitant radiochemotherapy was given in 2 cases. The rate of disease control on the ipsilateral side was 12/14. Two patients were treated by chemotherapy but died of their disease. The failure rate on the contralateral side was 2/14. These two patients were successfully salvaged. During follow-up, a primary tumour was detected in one case. At the end of the follow-up, 10 patients were alive. CONCLUSIONS: Modified radical neck dissection combined with postoperative radiation with or without chemotherapy could be considered in N1-N3 lymph node status. Despite generally advanced disease at presentation, patients presenting with cervical metastasis from an unknown primary carcinoma have a reasonable survival expectation and aggressive treatment is warranted. Careful follow-up is required for effective salvage treatment.

Avian flu: isolation of drug-resistant H5N1 virus.

The persistence of H5N1 avian influenza viruses in many Asian countries and their ability to cause fatal infections in humans have raised serious concerns about a global flu pandemic. Here we report the isolation of an H5N1 virus from a Vietnamese girl that is resistant to the drug oseltamivir, which is an inhibitor of the viral enzyme neuraminidase and is currently used for protection against and treatment of influenza. Further investigation is necessary to determine the prevalence of oseltamivir-resistant H5N1 viruses among patients treated with this drug.