Determination of plutonium and uranium in the same aliquot by potentiometric titration

A potentiometric titration method was developed for the determination of plutonium and uranium in the same aliquot in nitric acid medium. Plutonium was first determined by oxidation to Pu/VI/ by fuming with conc. HClO₄. Pu/VI/ formed was reduced to Pu/IV/ with known excess of Fe/II/ and the excess Fe/II/ was titrated with standard K₂Cr₂O₇ to a potentiometric end point. Uranium in the same solution was determined by reduction to U/IV/ with Fe/II/ in conc. H₃PO₄ medium and titrating U/IV/ formed with standard K₂Cr₂O₇ using the potentiometric end point detection technique. For the quantity of plutonium and uranium each in the range of 3–5 mg per aliquot a precision of ±0.2% and ±0.4%, respectively, was obtained.     

Availability of essential elements in bhasmas: Analysis of Ayurvedic metallic preparations by INAA

Summary Twenty bhasmas based on Ca, Fe, Zn, Hg, Ag, K, As, Cu, Sn and gemstones have been analyzed for main constituent elements along with minor (Na, K, Mg, Ca, P), trace (Cr, Mn, Fe, Co, Cu, Zn, Hg) and toxic elements by instrumental neutron activation analysis (INAA) including their C, H, N and S contents. Siddhamakaradhwaja, an Hg preparation and Swet parpati of K were found to be stoichiometrically HgS and KNO3     

Near IR overtone spectral investigations of cyclohexanol using local mode model--evidence for variation of anharmonicity with concentration due to hydrogen bonding

The near infrared vibrational overtone absorption spectrum of liquid phase cyclohexanol in carbon tetrachloride in different concentrations are examined in the region Deltav=2, 3 and 4. The free and bonded OH local mode mechanical frequency values and anharmonicity values obtained from fitting the overtones are analysed. The observation supports the conclusions drawn from earlier experimental studies on anharmonicity variation of OH-stretching vibrations of alcohols due to intermolecular hydrogen bonding. Our observation is also in agreement with the ab initio calculations on water dimer and trimer. Mechanical anharmonicity of bonded OH-stretching bands tends to increase as a consequence of strong hydrogen bonding at higher concentrations.     

Polarographic reduction of germanium

In a previous note the authors had reported the polarographic reduction of ravalent germanium. These observations were confirmed, and full data are presented here which show the two-step reduction of tetravalent germanium under the dropping mercury electrode, from ammoniacal-ammonium chloride solutions.     

On Riemann sums and Lebesgue integrals

Call a sequence of positive integers(m _k ) _k=1 ^∞ a chain ifm _k devidesm _k+1 and that it has dimensiond if it is a subset of the set of least common multiples ofd chains. In this paper we give a new and elementary proof that iff∈L(logL)^d?1([0, 1)) and(m _k ) _k=1 ^∞ is of dimensiond then $$\mathop {\lim }\limits_{N \to \infty } \frac{1}{N}\sum\limits_{n = 1}^N {f\left( {\left\{ {x + \frac{n}{{m_N }}} \right\}} \right)} = \int_X {fd\mu , a.e.,} $$ with respect to Lebesgue measure. This result was first proved byL. Dubins andJ. Pitman [2] using martingale theory.     

Effect of gamma-irradiation on the thermal decomposition of potassium chlorate

The thermal decomposition of -irradiated KClO₃ was studied by dynamic thermogravimetry. The reaction order, activation energy, frequency factor and entropy of activation were computed using the Coats-Redfern, Freeman-Carroll and Horowitz-Metzger methods and were compared with those of the unirradiated salt. The decomposition increases with the irradiation dose. The energy of activation decreases on irradiation. The mechanism for the decomposition of unirradiated and irradiated KClO₃ follows the Avrami model equation, 1-(1-)^1/3, and the rate controlling process is a phase boundary reaction assuming spherical symmetry.     

DMAP catalyzed reaction of β-ketoesters and dimethyl acetylenedicarboxylate: efficient synthesis of polysubstituted benzenes and biaryls

A DMAP catalyzed tandem addition-cyclization-dehydration sequence involving dimethyl acetylenedicarboxylate and β-ketoesters leading to polysubstituted benzene/biaryl derivatives is presented.