Electroweak couplings of the τ lepton

The tau lepton is the heaviest known lepton and studies of its production and decay allow measurements of its couplings to the electroweak gauge bosons. In particular, sensitive tests of the idea of lepton universality are possible, with the hope that some light will be shed on not just the nature of the origin of mass, but also on why there seem to be three generations. The recent LEP results provide most of this experimental data, and very recently measurements of the anomalous magnetic and electric dipole moments of the tau have been performed. I present an overview of all these results, and discuss what this means in the framework of the Standard Model and attempts to go beyond it.     

Measurement of total protein in urine: Comparison of two dye-binding procedures with a gel filtration/modified biuret method

Two dye-binding methods for the determination of urinary total protein concentration have been compared to a biuret-based procedure requiring a preliminary gel filtration step. The biuret-based procedure is claimed to be both specific and sensitive for the measurement of protein in urine. With those urines having relatively low protein concentrations, the dye-binding methods provide values about one-half of those given by the modified biuret procedure. This difference disappears when urines containing high levels of protein are measured. The lower results obtained at normal protein levels are most likely caused by the inability of dye-binding methods to measure proteins of high carbohydrate content (such as uromucoid) accurately. In spite of this limitation, both dye-binding methods appear suitable for routine use. In contrast to the biuret-based procedure, we found the dye-binding methods to be free from interferences by compounds known to appear in urine in high concentrations.     

A formal total synthesis of (+)-apicularen A: base-induced conversion of apicularen-derived intermediates into salicylihalamide-like products

A synthesis of apicularen precursor (-)-6 in 18 steps from D-glucal is reported. As (+)-6 has been converted into the potent, naturally occurring salicylate anti-cancer agent, (-)-apicularen A in 8 steps, this study constitutes a formal total synthesis of (+)-apicularen A. Key steps in the synthetic route include: (i) useful D-glucal elaboration processes, (ii) organometallic displacements at carbohydrate C-6 triflates using Knochel-type and related functionalised, aromatic Grignard reagents, (iii) stereoselective allyltrimethylsilane-acetal reactions generating C-allyl systems, (iv) stereocontrolled aldehyde allylation processes from both substrate and reagent, and (v) a novel Keck-type macrolactonisation. In addition, preliminary studies are reported in which a procedure has been devised to convert apicularen-derived intermediates into salicylihalamide-like products.     

Determination of rare-earth elements in Periyar River water (Kerala, India) and seawater (Mumbai, India) using neutron activation analysis

During the present work rare earth elements (REEs) in Periyar River water and in seawater from the region of Mumbai, India, have been measured via neutron activation analysis. To separate and concentrate REEs a pre-irradiation separation approach via ion exchange was adopted. Standard addition and radiotracer studies were carried out to validate the analytical methodology including the recoveries of the separations. The measured REE concentrations in the water samples are presented and discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Purification of arsenic contaminated ground water using hydrated manganese dioxide

An analytical methodology has been developed for the separation of arsenic from ground water using inorganic material in neutral medium. The separation procedure involves the quantitative retention of arsenic on hydrated manganese dioxide, in neutral medium. The validity of the separation procedure has been checked by a standard addition method and radiotracer studies. Neutron activation analysis (NAA), a powerful measurement technique, has been used for the quantitative determination of arsenic.     

Determination of leachable arsenic from glass ampoules

Appreciable amounts of different arsenic compounds are used in the manufacture of glass and glass ampoules (injection vials and bottles) used to store drugs. Exposure/intake of arsenic to human beings may result in skin ulceration, injury to mucous membranes, perforation of nasal septum, skin cancer and keratoses, especially of the palms and soles and may cause detrimental effects. Considering the toxicity of arsenic, even if traces of arsenic from such glass containers/ampoules are leached out, it can impart damage to human beings. To check the possibility of leaching of arsenic from glass ampoules, a simple methodology has been developed. Different makes and varieties of glass ampoules filled with de-ionized water were subjected to high pressure and temperature leaching for varying amount of time using autoclave to create extreme conditions for the maximum leaching out of the analyte. Subsequently, the determination of the arsenic contents in leached water using neutron activation analysis is reported in this paper in detail with observations. This revised version was published online in August 2006 with corrections to the Cover Date.     

Macro micro separation of selenium and tellurium: Application to NAA</p> </p>

Summary A simple pre-irradiation separation approach has been worked out for the determination of traces of tellurium in high purity selenium followed by neutron activation analysis (NAA) for the end determination of the analyte/s. The difference in volatilities of these elements has been utilized for the separation of the analyte from the matrix. The complete volatility of selenium at ~600 °C was established using neutron activation analysis and selenium radiotracer. Standard addition was used to validate the results. The proposed method of separation of selenium prior to irradiation could make the determination of tellurium possible and also improved the detection limit by several folds.</p> </p>     

Slow Magnetic Relaxation and Single‐Molecule Toroidal Behaviour in a Family of Heptanuclear {CrIIILnIII6} (Ln=Tb,Ho, Er) Complexes

The synthesis, magnetic properties, and theoretical studies of three heterometallic {Cr^IIILn^III₆} (Ln=Tb, Ho, Er) complexes, each containing a metal topology consisting of two Ln₃ triangles connected via a Cr^III linker, are reported. The {CrTb₆} and {CrEr₆} analogues display slow relaxation of magnetization in a 3000 Oe static magnetic field. Single‐crystal measurements reveal opening up of the hysteresis loop for {CrTb₆} and {CrHo₆} molecules at low temperatures. Ab initio calculations predict toroidal magnetic moments in the two Ln₃ triangles, which are found to couple, stabilizing a con‐rotating ferrotoroidal ground state in Tb and Ho examples and extend the possibility of observing toroidal behaviour in non Dy^III complexes for the first time.